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Cited by 337Laser-Matter Interactions and ApplicationsAdvanced X-ray Imaging TechniquesX-ray Spectroscopy and Fluorescence Analysis

Roadmap of ultrafast x-ray atomic and molecular physics

Open access
Young, Linda, Ueda, Kiyoshi, Gühr, Markus, Bucksbaum, Philip H, Simon, Marc, Mukamel, Shaul, Rohringer, Nina, Prince, Kevin C +19 more·2018·Journal of Physics B: Atomic, Molecular and Optical Physics
DOI 10.1088/1361-6455/aa9735
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Abstract

X-ray free-electron lasers (XFELs) and table-top sources of x-rays based upon high harmonic generation (HHG) have revolutionized the field of ultrafast x-ray atomic and molecular physics, largely due to an explosive growth in capabilities in the past decade. XFELs now provide unprecedented intensity (10 20 W cm −2 ) of x-rays at wavelengths down to ∼1 Ångstrom, and HHG provides unprecedented time resolution (∼50 attoseconds) and a correspondingly large coherent bandwidth at longer wavelengths. For context, timescales can be referenced to the Bohr orbital period in hydrogen atom of 150 attoseconds and the hydrogen-molecule vibrational period of 8 femtoseconds; wavelength scales can be referenced to the chemically significant carbon K-edge at a photon energy of ∼280 eV (44 Ångstroms) and the bond length in methane of ∼1 Ångstrom. With these modern x-ray sources one now has the ability to focus on individual atoms, even when embedded in a complex molecule, and view electronic and nuclear motion on their intrinsic scales (attoseconds and Ångstroms). These sources have enabled coherent diffractive imaging, where one can image non-crystalline objects in three dimensions on ultrafast timescales, potentially with atomic resolution. The unprecedented intensity available with XFELs has opened new fields of multiphoton and nonlinear x-ray physics where behavior of matter under extreme conditions can be explored. The unprecedented time resolution and pulse synchronization provided by HHG sources has kindled fundamental investigations of time delays in photoionization, charge migration in molecules, and dynamics near conical intersections that are foundational to AMO physics and chemistry. This roadmap coincides with the year when three new XFEL facilities, operating at Ångstrom wavelengths, opened for users (European XFEL, Swiss-FEL and PAL-FEL in Korea) almost doubling the present worldwide number of XFELs, and documents the remarkable progress in HHG capabilities since its discovery roughly 30 years ago, showcasing experiments in AMO physics and other applications. Here we capture the perspectives of 17 leading groups and organize the contributions into four categories: ultrafast molecular dynamics, multidimensional x-ray spectroscopies; high-intensity x-ray phenomena; attosecond x-ray science.

AI snapshot

Written from the paper’s full text.

TL;DR

This roadmap surveys ultrafast x-ray atomic and molecular physics enabled by XFELs and HHG sources, organizing perspectives from 17 leading groups into four categories: ultrafast molecular dynamics, multidimensional x-ray spectroscopies, high-intensity x-ray phenomena, and attosecond x-ray science. It documents source capabilities, scientific opportunities, and technical challenges as new Ångstrom-wavelength XFEL facilities open and HHG reaches attosecond time resolution.

Key findings

  • XFELs provide unprecedented x-ray intensity of 10^20 W cm^-2 at wavelengths down to ∼1 Ångstrom, while HHG provides time resolution of ∼50 attoseconds and large coherent bandwidth at longer wavelengths.
  • The roadmap frames relevant scales by the hydrogen Bohr orbital period of 150 attoseconds, the hydrogen-molecule vibrational period of 8 femtoseconds, the carbon K-edge at ∼280 eV (44 Ångstroms), and the methane bond length of ∼1 Ångstrom.
  • Three new Ångstrom-wavelength XFEL facilities opened for users around the time of the roadmap—European XFEL, Swiss-FEL, and PAL-FEL in Korea—almost doubling the worldwide number of XFELs.
  • Specific advances cited include attosecond pulses as short as 43 as and 53 as, charge migration across iodoacetylene in less than 1 fs, transient lattice contraction within 80 fs, and emission of more than 50 electrons within a few tens of fs at x-ray intensities exceeding 10^19 W cm^-2.

Methods

  • This is a roadmap/community-perspective article, not a primary experimental study; it captures the perspectives of 17 leading groups and organizes contributions into four categories: ultrafast molecular dynamics, multidimensional x-ray spectroscopies, high-intensity x-ray phenomena, and attosecond x-ray science.
  • The text reviews source capabilities and experimental techniques for XFELs and HHG, including coherent diffractive imaging, nonlinear x-ray processes, multidimensional spectroscopy, photoionization time-delay measurements, and attosecond transient absorption.
  • It discusses current and future challenges and advances needed in sources, instrumentation, theory, and computation, with examples drawn from experiments and simulations across atoms, molecules, clusters, liquids, and solids.

Limitations

  • The paper states that most XFELs are based on self-amplified spontaneous emission (SASE), lack longitudinal coherence, struggle to obtain pulse lengths shorter than a few femtoseconds, and struggle to synchronize with external sources.
  • It states that HHG sources have exquisite temporal coherence and pulse duration but are challenged to obtain large photon numbers per pulse, extend to short wavelengths, and achieve high average power.
  • It notes that low repetition rates at current XFELs limit coincidence measurements, that SASE spectral fluctuations hamper nonlinear x-ray spectroscopy, and that theoretical treatment of high-intensity x-ray-driven polyatomic systems remains a central challenge; the roadmap format itself is not a systematic review or meta-analysis.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1088/1361-6455/aa9735

Cites

226 of 226 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

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  • Findingcitation

    Conventional electron spectroscopy in the tender x-ray domain can be used to study double core hole states by promoting one core electron into an empty orbital and simultaneously ejecting another core electron into the continuum and detecting it.

    “We have shown that conventional electron spectroscopy in the tender x-ray domain can be used to study DCH states: one core electron is promoted into an empty orbital and another core electron is simultaneously ejected into the continuum and detected [29,30].”
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  • Findingcitation

    Vector momenta of ions and photoelectrons recorded in a multicoincidence COLTRIMS setup reveal fragmentation dependence of the localization/delocalization of a deep inner-shell hole in a symmetric molecule.

    “The vector momenta of the ions and the photoelectrons have been recorded in a multicoincidence COLTRIMS setup revealing interesting features such as fragmentation dependence of the localization/ delocalization of a deep inner-shell hole in a symmetric molecule [27].”
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    • cites [27] source

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  • Findingcitation

    At high photon energy, the large kinetic energy of the escaping photoelectron induces large translational recoil observed via the atomic Doppler Auger effect.

    “At high photon energy, the large kinetic energy of the escaping photoelectron induces large translational recoil observed via the atomic Doppler Auger effect [28]”
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  • Findingcitation

    On the CS2 molecule, a strong evolution of the RIXS spectral profile with excitation energy much detuned below the lowest discrete resonance has been observed.

    “On the CS 2 molecule, a strong evolution of the RIXS spectral profile with the excitation energy much detuned below the lowest discrete resonance has been observed.”
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  • Findingcitation

    The chemical information of the oxidation state of different Mn compounds was demonstrated to be preserved.

    “More importantly, similarly to the 'diffract before destroy' approach of femtosecond serial crystallography, the chemical information of the oxidation state of the different Mn compounds was demonstrated to be preserved.”
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    Findingnone given

    Photon-ion and Auger electron-ion coincidences are currently impossible to measure in this energy domain because the luminosity of the x-ray or electron spectrometers is not high enough.

    “Photon-ion and Auger electron-ion coincidences are, for the moment, impossible to measure in this energy domain because the luminosity of the x-ray or electron spectrometers are not high enough.”
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  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Findingnone given

    At the carbon K-edge XFELs produce many orders of magnitude more photons/pulse/1% bandwidth than HHG sources.

    “At the carbon K-edge XFELs produce many orders of magnitude more photons/pulse/1% bandwidth than HHG sources.”
    Quote in the paperNot a substantial claim

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    Findingcitation

    Amplified spontaneous x-ray emission and stimulated resonant inelastic x-ray Raman scattering have been demonstrated in atomic Ne in the soft x-ray spectral range.

    “Despite the ultrahigh intensities necessary for realizing stimulated x-ray emission (10 17 -10 18 W cm -2 in the soft and 10 19 -10 20 W cm -2 in the hard x-ray range), amplified spontaneous x-ray emission [58] and stimulated resonant inelastic x-ray Raman scattering (sRIXS) [59] have been demonstrated in atomic Ne in the soft x-ray spectral range.”
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    Findingcitation

    Post-sorting the pair of pulses according to their total pulse energy and electron-beam energy resulted in very stable, reproducible spectral averages, so that relative differences of greater than 5% are measurable using this pulse combination.

    “We, however, demonstrated that post-sorting the pair of pulses according to their total pulse energy and the electron-beam energy resulted in very stable, reproducible spectral averages, so that relative differences of >5% are measurable using this pulse combination [63].”
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    Findingcitation

    Schemes have been developed to create multipulse and polychromatic radiation, and FEL light has been used to pump atomic lasers in the x-ray region.

    “Schemes have been developed to create multipulse and polychromatic radiation, and FEL light has been used to pump atomic lasers in the x-ray region [58,68].”
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    Findingnone given

    The probability for fluorescent decay in the soft x-ray range is below 1%, representing a challenge for signal detection.

    “Unfortunately, the probability for fluorescent decay in the soft x-ray range is below 1%, and this represents a challenge for signal detection.”
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    • Rests on an assumption: The probability for fluorescent decay in the soft x-ray range is below 1%.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation

    The LCLS was specified to produce 200 fs pulses, but soon produced few fs pulses.

    “The LCLS was specified to produce 200 fs pulses, but soon produced few fs pulses [67].”
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    Findingreasoning

    Spectrometers are inefficient (typical acceptance less than 10^-5 of the full solid angle), so XES or RIXS require counting single photons for hours to obtain useful information.

    “Spectrometers are also inefficient (typical acceptance <10 -5 of the full solid angle), so soft x-ray emission spectroscopy (XES) or RIXS are experiments where single photons have to be counted for hours in order to obtain useful information.”
    Quote in the paperSubstantial claim

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    Findingcitation

    The XUV/soft x-ray laser FERMI is the first fully coherent FEL, as the light possesses the full longitudinal coherence missing from SASE FELs.

    “coherent FEL, as the light possesses the full longitudinal coherence missing from SASE FELs [69].”
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    Findingcitation

    Recently, FOPA has been modified and pumped by 250 mJ ps pulses, delivering ∼30 mJ two-cycle, 1.8 μm pulses, representing ∼2.5 TW peak power.

    “Recently, FOPA has been modified and pumped by 250 mJ ps pulses, delivering ∼30 mJ two-cycle, 1.8 μm pulses [158], representing ∼2.5 TW of peak power.”
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    Findingreasoning

    This sets a narrow optimum operating range that, depending on the gas and laser wavelength, results in conversion efficiency approaching 10 -3 for the VUV, decreasing slowly to ∼10 -7 for soft x-ray generation using mid-IR lasers.

    “This sets a narrow optimum operating range that, depending on the gas and laser wavelength, results in conversion efficiency approaching 10 -3 for the VUV, decreasing slowly to ∼10 -7 for soft x-ray generation using mid-IR lasers.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    With OPA/OPCPA sources, half-cycle cut-offs in the water window spectral range have been observed, confirming generation of isolated attosecond x-ray pulses in the water window.

    “With these OPA/OPCPA sources, half-cycle cut-offs in the water window spectral range have been observed, confirming the generation of isolated attosecond x-ray pulses in the water window [155,156].”
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    Findingcitation

    We have measured ionization and recombination dynamics in large rare-gas clusters and observed XUV-induced Rabi oscillations in two-color double ionization of Ar.

    “As an example of (1), we have measured ionization and recombination dynamics in large rare-gas clusters [182,183] and have observed XUV-induced Rabi oscillations in two-color double ionization of Ar [184]”
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    Findingnone given

    Significant progress in the last few years has allowed production of focused XUV intensities well beyond 10^12 W cm^-2, whereas early HHG sources typically allowed <10^11 W cm^-2.

    “While early HHG sources typically allowed the generation of focused XUV intensities <10 11 W cm -2 , significant progress in the last few years has allowed the production of intensities well beyond 10 12 W cm -2 .”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation

    Figure 22 shows the difference in time delays corresponding to ionization in the 3s and 3p ionization of argon.

    “Figure 22 shows the difference in the time delays corresponding to ionization in the 3s and 3p ionization of argon [187].”
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    • cites [187] source

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    Findingnone given

    In many cases, τcc can be accurately calculated; in the case shown in figure 22, its contribution amounts to -70 as.

    “In many cases, τ cc can be accurately calculated (e.g. in the case shown in figure 22, its contribution amounts to -70 as).”
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    Findingreasoning

    Calculations agree well with each other and with experimental results for sideband 22 (34 eV) and 24 (37 eV) but deviate for sideband 26 (40 eV).

    “The calculations agree well with each other and with the experimental results for sideband 22 (34 eV) and 24 (37 eV) but deviate for sideband 26 (40 eV).”
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  • Probably not a substantial claim: may not pass S4 (based).

    Findingnone given

    In the case presented above, the 3p→εd channel is mostly dominant.

    “Note that in the case presented above, the 3p→εd channel is mostly dominant.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    τcc becomes very large at low kinetic energies, preventing precise time delay measurements.

    “It becomes very large at low kinetic energies, thus preventing precise time delay measurements [188,190].”
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    Findingcitation

    Phase variation of sideband 16 as a function of the energy of harmonic 17, close to the 3s -1 4p quasibound state.

    “Phase variation of sideband 16 as a function of the energy of harmonic 17, close to the 3s -1 4p quasibound state.”
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    • cites [192] source

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    Findingcitation

    Measured difference in photoionization time delays from the 3s and 3p shells in Ar.

    “Measured difference in photoionization time delays from the 3s and 3p shells in Ar (solid dots).”
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    Findingcitation

    X-ray fs identification of the key transition state labeled 2 A for ring opening of cyclohexadiene.

    “X-ray fs identification of the key transition state labeled 2 A, blue points, for ring opening of cyclohexadiene.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [216] source

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  • May combine two claims.

    Interpretationreasoning

    This method gives access to the different states converging toward double core hole states and allows determination of their core-hole lifetimes.

    “We can then have access to the different states converging toward DCH states and determine their core-hole lifetimes.”
    Quote in the paperSubstantial claim

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    Premisereasoning

    Because a number of electrons escape from the cluster, the cluster becomes highly charged and starts trapping electrons that are emitted from the individual atoms, forming a nanoplasma.

    “Because a number of electrons escape from the cluster, the cluster becomes highly charged and starts trapping electrons that are emitted from the individual atoms.A nanoplasma is thus formed.”
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    Premisecitation

    Rovibronic wavepackets in iodine, metal compounds in liquids and organic ring openings have all been observed with unprecedented time resolution.

    “Rovibronic wavepackets in iodine, metal compounds in liquids and organic ring openings have all been observed with unprecedented time resolution [10,19,20].”
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  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given

    HHG provides unprecedented time resolution of approximately 50 attoseconds and a correspondingly large coherent bandwidth at longer wavelengths.

    “HHG provides unprecedented time resolution (∼50 attoseconds) and a correspondingly large coherent bandwidth at longer wavelengths.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Because of the short core-hole lifetimes and large kinetic energies of the emitted Auger electrons, just above threshold large post collision interactions (Coulomb interactions between the photoelectron, Auger and the ion) as well as recapture of the photoelectron have been observed.

    “Because of the short core-hole lifetimes and large kinetic energies of the emitted Auger electrons, just above threshold large post collision interactions (Coulomb interactions between the photoelectron, Auger and the ion) as well as recapture of the photoelectron have been observed [23].”
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    • cites [23] Piancastelli M N, 2017, J. Phys. B: At. Mol. Opt. Phys. source

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  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given

    Raising the hard x-ray cut-off energy of x-ray FELs will increase the spatial resolution of scattering measurements, opening a path to measure both motion and transient geometries in excited states such as molecules approaching conical intersections.

    “Raising the hard x-ray cut-off energy of x-ray FELs will increase the spatial resolution of scattering measurements, opening a path to measure both motion and transient geometries in excited states such as molecules approaching conical intersections.”
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  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Competitions between sequential photoemission and Auger cascades have been studied extensively using rare-gas atoms as a target.

    “Competitions between sequential photoemission and Auger cascades have been studied extensively using rare-gas atoms as a target [1][2][3].”
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    • cites [1][2][3]

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  • Classified as probably not a substantial claim.

    Interpretationreasoning

    XFELs and table-top sources of x-rays based upon high harmonic generation have revolutionized the field of ultrafast x-ray atomic and molecular physics, largely due to an explosive growth in capabilities in the past decade.

    “X-ray free-electron lasers (XFELs) and table-top sources of x-rays based upon high harmonic generation (HHG) have revolutionized the field of ultrafast x-ray atomic and molecular physics, largely due to an explosive growth in capabilities in the past decade.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationreasoning

    The unprecedented time resolution and pulse synchronization provided by HHG sources has kindled fundamental investigations of time delays in photoionization, charge migration in molecules, and dynamics near conical intersections that are foundational to AMO physics and chemistry.

    “The unprecedented time resolution and pulse synchronization provided by HHG sources has kindled fundamental investigations of time delays in photoionization, charge migration in molecules, and dynamics near conical intersections that are foundational to AMO physics and chemistry.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Because of the cascade Auger effect, the ultrafast nuclear motion occurring in the first intermediate state is amplified through the different dissociative intermediate states and leads to the ultrafast dissociation, with the Auger electron emitted by the fragment and not by the molecule.

    “Because of the cascade Auger effect, the ultrafast nuclear motion occurring in the first intermediate state is amplified through the different dissociative intermediate states and leads to the ultrafast dissociation as illustrated in figure 6: the Auger electron is emitted by the fragment and not by the molecule [24,25].”
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    Premisecitation

    X-ray imaging experiments for rare-gas clusters have also been combined with optical laser-pump techniques and have just started to probe the structural evolution of clusters heated by an optical laser.

    “X-ray imaging experiments for rare-gas clusters have also been combined with optical laser-pump techniques and have just started to probe the structural evolution of clusters heated by an optical laser [11].”
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    Premisenone given

    XFELs now provide unprecedented intensity of 10^20 W cm^-2 of x-rays at wavelengths down to approximately 1 Angstrom.

    “XFELs now provide unprecedented intensity (10 20 W cm -2 ) of x-rays at wavelengths down to ∼1 Ångstrom”
    Quote in the paperNot a substantial claim

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    Premisecitation

    X-ray diffraction experiments of isolated molecules in photoreaction have become feasible in the last few years, demonstrating that watching atomic motion in an isolated molecule is no longer a dream.

    “X-ray diffraction experiments of isolated molecules in photoreaction have, however, become feasible in the last few years [10], demonstrating that watching atomic motion in an isolated molecule is no longer a dream.”
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  • May combine two claims.

    Interpretationreasoning

    With modern x-ray sources one can focus on individual atoms, even when embedded in a complex molecule, and view electronic and nuclear motion on their intrinsic scales of attoseconds and Angstroms.

    “With these modern x-ray sources one now has the ability to focus on individual atoms, even when embedded in a complex molecule, and view electronic and nuclear motion on their intrinsic scales (attoseconds and Ångstroms).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning

    X-ray techniques can be designed by learning lessons from the visible and infrared regimes.

    “Similarly, x-ray techniques can be designed by learning lessons from the visible and infrared regimes.”
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  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    High-harmonic-generation x-ray pulses are limited to XUV and soft x-ray below 1 keV.

    “They are further limited to XUV and soft x-ray <1 keV.”
    Quote in the paperNot a substantial claim

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    Interpretationnone given

    By carefully choosing the time order, frequencies and propagation direction of a series of x-ray pulses, different x-ray nonlinear response diagrams contributing to higher-order susceptibility can be addressed that probe electron dynamics with high temporal and spatial resolution and give novel insight into dynamical properties of electronic coherence.

    “Similar to optical nonlinear spectroscopy, by carefully choosing the time order, frequencies and propagation direction of a series of x-ray pulses, different x-ray nonlinear response diagrams contributing to higher-order susceptibility can be addressed that probe electron dynamics with high temporal and spatial resolution, and give novel insight into dynamical properties of electronic coherence.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The short correlation time of noisy light sources has been exploited in the optical regime to perform femtosecond experiments with stochastic nanosecond light.

    “The short correlation time of noisy light sources has been exploited in the optical regime to perform femtosecond experiments with stochastic nanosecond light, see chapter 10 in [37].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [37] Mukamel S, 1995, Principles of Nonlinear Optical Spectroscopy

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  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    A combination of broadband femtosecond and narrowband picosecond pulses has proven to provide optimal temporal and spectral resolution in Raman spectroscopy in the optical regime.

    “A combination of broadband (femtosecond) and narrowband (picosecond) pulses has proven to provide an optimal temporal and spectral resolution in Raman spectroscopy in the optical regime.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Time-resolved, off-resonant scattering (diffraction) provides movie-like snapshots of the charge density.

    “Time-resolved, off-resonant scattering (diffraction) provides movie-like snapshots of the charge density.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning

    These signals offer new powerful windows into many-body effects in electron and nuclear dynamics.

    “These signals offer new powerful windows into many-body effects in electron and nuclear dynamics.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisenone given

    Charge densities are obtained in conventional diffraction and used to probe the structure of molecules in a given electronic state.

    “The former, known as charge densities, are obtained in conventional diffraction and used to probe the structure of molecules in a given electronic state.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Conventional nonlinear spectroscopy uses classical light to detect matter properties through the variation of its response with frequencies or time delays.

    “Conventional nonlinear spectroscopy uses classical light to detect matter properties through the variation of its response with frequencies or time delays.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Premisereasoning

    The design and interpretation of nonlinear spectroscopy of core and valence excitations pose enormous theoretical and simulation challenges.

    “The design and interpretation of nonlinear spectroscopy of core and valence excitations pose enormous theoretical and simulation challenges.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    By using femtosecond to attosecond x-ray pulses resonant with core transitions in selected atoms, multidimensional techniques can be extended to probing core electronic states and couplings, real-time tracking of valence electronic wavepackets, and electronic coherences.

    “By using femtosecond to attosecond x-ray pulses resonant with core transitions in selected atoms, these techniques can be extended to probing core electronic states and couplings, the real-time tracking of impulsively created valence electronic wavepackets and electronic coherences.”
    Quote in the paperSubstantial claim

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    Interpretationnone given

    Core resonant excitations offer a fast and versatile way to trigger valence electronic excitations impulsively at selected positions and times and monitor their subsequent dynamics via stimulated Raman processes.

    “Apart from the direct study of core excitations, core resonant excitations offer a fast and versatile way to trigger valence electronic excitations impulsively at selected positions and times and monitor their subsequent dynamics via stimulated Raman processes.”
    Quote in the paperSubstantial claim

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    Interpretationcitation

    At conical intersections, the energy splitting of the electronic states involved in the coherence can be read from the Raman shift, and the coherent oscillation period reveals this time-dependent level splitting averaged over the nuclear wavepacket.

    “At conical intersections, the energy splitting of the electronic states involved in the coherence can be read from the Raman shift and the coherent oscillation period reveals this time-dependent level splitting averaged over the nuclear wavepacket [43].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [43] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given

    The complex nature of excited-state dynamics leads to characteristic patterns in nonlinear 2D correlation plots, which provide signatures of strongly coupled electron and nuclear dynamics.

    “The complex nature of excited-state dynamics leads to characteristic patterns in nonlinear 2D correlation plots, which provide signatures of strongly coupled electron and nuclear dynamics.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Many experiments use the HHG field itself as the signal; such signals are robust but harder to interpret than a pump-probe because the spectroscopic information is convoluted with the HHG multistep mechanism.

    “Many experiments use the HHG field itself as the signal [41].Such signals are robust but harder to interpret than, e.g., a pumpprobe, since the spectroscopic information is convoluted with the HHG multistep mechanism.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [41] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given

    X-ray pulses produced via high-harmonic generation are easier to create and of much higher quality than XFEL pulses, but they are of significantly lower intensity, making it harder to use them in higher-order nonlinear spectroscopies.

    “X-ray pulses produced via high-harmonic generation are easier to create and of much higher quality than XFEL pulses, but they are of significantly lower intensity, making it harder to use them in higher-order nonlinear spectroscopies.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Historically, stimulated Raman has been the most robust nonlinear optical technique.

    “Historically, stimulated Raman has been the most robust nonlinear optical technique.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    The key nonlinear optical spectroscopy experiments were based on earlier ideas developed and implemented in radio waves (NMR).

    “The key nonlinear optical spectroscopy experiments were based on earlier ideas developed and implemented in radio waves (NMR).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Transition charge densities are associated with electronic and vibrational coherence and carry additional dynamical information about electronic excitations and their delocalization.

    “The latter, known as transition charge densities, are associated with electronic and vibrational coherence and carry additional dynamical information about electronic excitations and their delocalization [44].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [44] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    The nonlinear response of valence electrons to multiple cores excited at variable delays provides a unique window into electron structure and correlations.

    “The nonlinear response of valence electrons to multiple cores excited at variable delays provides a unique window into electron structure and correlations.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationreasoning

    The same idea can be extended by combining attosecond HHG and femtosecond FEL x-ray pulses.

    “The same idea can be extended by combining attosecond (HHG) and femtosecond (FEL) x-ray pulses.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    These multidimensional diffraction measurements require single-molecule photon counting and provide information on charge fluctuations through multi-point correlation functions of the charge density.

    “These require singlemolecule photon counting and provide information on charge fluctuations through multi-point correlation functions of the charge density.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    Tunable, intense attosecond x-ray pulses can probe ultrafast processes such as intersystem crossing and radiationless decay and reveal the nature of elementary photophysical and photochemical events.

    “Tunable, intense attosecond x-ray pulses can probe such ultrafast processes and reveal the nature of elementary photophysical and photochemical events [41].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [41] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationnone given

    Raman signals do not require phase control of the pulses and can probe valence excitations that are more chemically relevant than core excitations.

    “Notable advantages of Raman signals are that they do not require phase control of the pulses and their ability to probe valence excitations that are more chemically relevant than core excitations.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    X-ray pulses with broad bandwidth (10 eV for a 100 attosecond pulse) can create coherent superpositions of many electronic and vibrational states localized at a target atom and monitor their evolution on a very short time scale.

    “Thanks to their broad bandwidth (10 eV for a 100 attosecond pulse), x-ray pulses can create coherent superpositions of a large number of electronic and vibrational states that are localized at a target atom, and monitor their evolution on a very short time scale.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Optical pulses can excite vibrations impulsively.

    “Optical pulses can excite vibrations impulsively.Broadband x-ray pulses can do the same to valence electronic excitations.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Nonlinear x-ray spectroscopies can track the ultrafast passage through conical intersections and reveal the time evolution and couplings of electronic coherences.

    “Nonlinear x-ray spectroscopies can track the ultrafast passage through conical intersections and reveal the time evolution and couplings of electronic coherences.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisenone given

    Resonant core transitions provide a short time window limited by the core lifetime.

    “Resonant core transitions provide a short time window, limited by the core lifetime.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisenone given

    Coherent multidimensional spectroscopy involves several perturbations followed by a single measurement, whereas multidimensional diffraction consists of a series of measurements.

    “Note an important qualitative difference: coherent multidimensional spectroscopy involves several perturbations followed by a single measurement, whereas multidimensional diffraction consists of a series of measurements.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given

    Quantum light opens up new avenues for spectroscopy by utilizing parameters of the quantum state of light as novel control knobs and through the variation of photon statistics by coupling to quantum light.

    “Quantum light opens up new avenues for spectroscopy by utilizing parameters of the quantum state of light as novel control knobs and through the variation of photon statistics by coupling to quantum light.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Historically, coherent nonlinear spectroscopy has gradually evolved towards higher frequency regimes as phase control of the relevant light sources became feasible.

    “Historically, coherent nonlinear spectroscopy have gradually evolved towards higher frequency regimes as phase control of the relevant light sources became feasible.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    The direct signal of stimulated Raman scattering is not background free and is measured in homodyne detection with the transmitted x-ray probe beam that stimulates the Stokes transition.

    “In contrast to the more sophisticated nonlinear spectroscopies involving higher-order x-ray susceptibilities, the direct signal of stimulated Raman scattering is not background free and measured in homodyne detection with the transmitted x-ray probe beam that stimulates the Stokes transition.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    Four-wave mixing has a special place since it is at the basis of most experimental methods and is the lowest order nonlinear process that does not vanish by reason of sample symmetry considerations.

    “Among wave mixing processes, four-wave mixing (FWM) has a special place, since it is at the basis of most experimental methods, besides being the lowest order nonlinear process that does not vanish by reason of sample symmetry considerations.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    In nonlinear ultrafast time-resolved techniques, state-specific information is often provided through multiphoton resonances with combinations of sequential photons.

    “In nonlinear ultrafast timeresolved techniques, state-specific information is often provided through multiphoton resonances with combinations of sequential photons.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Since the first short-wavelength FEL FLASH began operation in Hamburg, development has been very rapid.

    “Since the first short-wavelength FEL FLASH began operation in Hamburg [66], development has been very rapid.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [66] Tiedtke K, 2009, New J. Phys. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Direct two-photon processes have been observed in above-threshold ionization and in formation of double core hole states.

    “Direct two-photon processes have been observed in the manifestation of above threshold ionization [75] and formation of double core hole states [76].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [75] source

      Not checked in the free run.

    • cites [76] source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    Extending FWM to the XUV and soft x-ray regime would open up the possibility to probe the sample with chemical selectivity exploiting electronic resonances.

    “Extending FWM to the XUV and soft x-ray regime would open up the possibility to probe the sample with chemical selectivity exploiting electronic resonances.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    FWM with optical lasers is an important technique that can be used in fields as diverse as combustion science and molecular spectroscopy.

    “FWM with optical lasers is an important technique, which can be used in fields as diverse as combustion science [70] and molecular spectroscopy [71].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [70] source

      Not checked in the free run.

    • cites [71] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    In the course of the sRIXS process in optically thick samples, the x-ray pulses are generally heavily attenuated.

    “Moreover, in the course of the sRIXS process in optically thick samples, the x-ray pulses are generally heavily attenuated.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    Different nonlinear processes can typically be ordered by the number of incident photons: sum frequency generation, two-photon absorption, and stimulated emission use two photons; time-resolved transient gratings or four-wave mixing use three incoming photons.

    “The different nonlinear processes can typically be ordered by the number of incident photons: sum frequency generation, two-photon absorption, and stimulated emission use two photons; other nonlinear x-ray phenomena, such as time-resolved transient gratings (XUV-TG) or four-wave mixing (XUV-FWM) spectroscopy, use three incoming photons.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    Fluorescent decays in the soft x-ray region allow unique access to the structure of the occupied valence states while keeping the element selectivity and chemical state specificity of soft x-ray spectroscopies.

    “Fluorescent decays in the soft x-ray region allow unique access to the structure of the occupied valence states, while keeping the element selectivity and chemical state specificity of soft x-ray spectroscopies.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    With such techniques, two to three orders of magnitude in signal levels can be gained through suppression of Auger processes, while the beam directed into the spectrometer promises about five orders of magnitude gain in detected signal levels.

    “With such techniques, two to three orders of magnitude in the signal levels can be gained through the suppression of Auger processes, while the beam directed into the spectrometer promises to gain about five orders of magnitude in detected signal levels-clearly having the potential to revolutionize how we can study matter with XES or RIXS based spectroscopies.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    The high pulse energies available ensure that nonlinear optics can cross the frontier into this new wavelength range.

    “The high pulse energies available ensure that nonlinear optics can cross the frontier into this new wavelength range.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    A stimulated beam containing the same information as a fluorescence spectrum can be formed, mitigating the low acceptance angle of the spectrometers and suppressing the dominating Auger decays that also create electronic damage to the sample.

    “A stimulated beam containing the same information as a fluorescence spectrum can be formed-both mitigating the low acceptance angle of the spectrometers, and suppressing the dominating Auger decays that also create electronic damage to the sample.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    In the quantum mechanical world, manipulation can be done by the established methods of coherent control.

    “In the quantum mechanical world this can be done by the established methods of coherent control (figure 10).”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning

    This would allow monitoring charge and energy transfer and understanding photodynamics.

    “This would allow monitoring charge and energy transfer and understanding photodynamics.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    Nonlinear spectra can be obtained by applying two sub-fs pulses tuned to specific absorption edges and measuring the integrated Raman gain of the second probe pulse as a function of the sample delay time.

    “Nonlinear spectra can be either obtained by applying two sub-fs pulses tuned to specific absorption edges of the molecule of interest and measuring the integrated Raman gain of the second probe pulse as a function of the sample delay time.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Optical coherent control is temporally limited to pulses that are several times the duration of an optical cycle, which is several femtoseconds.

    “Optical coherent control is temporally limited to pulses that are several times the duration of an optical cycle, which is several femtoseconds.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    The x-ray optical cross-correlation measurement relies on a change of index of refraction of an insulator by the x-ray pulse and typically requires an unattenuated x-ray beam.

    “The x-ray optical cross-correlation measurement relies on a change of index of refraction of an insulator by the x-ray pulse and typically requires an unattenuated x-ray beam.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    Free-electron lasers are extending laboratory laser experiments to shorter wavelengths and adding element and chemical state specificity by exciting and probing electronic transitions from core levels.

    “Free-electron lasers (FELs) are extending laboratory laser experiments to shorter wavelengths, and adding element and chemical state specificity by exciting and probing electronic transitions from core levels.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Depending on the different types of nonlinear x-ray spectroscopy, different pulse sequences are necessary.

    “Depending on the different types of nonlinear x-ray spectroscopy, different pulse sequences are necessary.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    In the XUV to x-ray range, the periods are from hundreds to a few attoseconds.

    “In the XUV to x-ray range, the periods are from hundreds to a few attoseconds.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning

    When the coherent control approach is developed for FELs, the new frontiers opened up include control of inner valence and core levels, and consequently chemical sensitivity.

    “When this approach is developed for FELs, the new frontiers opened up include control of inner valence and core levels, and consequently chemical sensitivity.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Combinations of multiple x-ray photons resonant with core transitions can characterize different excitation processes due to specific sequences of light-matter interaction.

    “Theoretically, combinations of multiple x-ray photons resonant with core transitions can also characterize different excitation processes due to specific sequences of light-matter interaction.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    For two- or multiphoton processes, absorption of each additional photon triggers similar dynamics on a modified set of ionic potential surfaces.

    “Furthermore, for two-or multiphoton processes, the absorption of each additional photon triggers similar dynamics now unfolding on a modified set of ionic potential surfaces.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    Controlled production of FEL pulses enables control of the spectral phase of the pulses, and few-attosecond temporal resolution was realized using interference between two-photon absorption of the fundamental and one-photon absorption of the second harmonic.

    “The controlled production of the FEL pulses also enables the control of the spectral phase of the pulses and few attosecond temporal resolution was realized in an experiment using the interference between ionization processes induced by two-photon absorption of the fundamental radiation and one-photon absorption of the second harmonics.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    It is possible to fabricate extremely large mirrors (80 cm length) with ultrahigh surface flatness (50 nrad).

    “The quality of focusing mirrors has also strongly increased and it is possible to fabricate extremely large mirrors (80 cm length) with ultrahigh surface flatness (50 nrad).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    Specially designed 1D imaging fluorescence spectrometers enable probing of interaction of a dense molecular target with intense XUV radiation in the direction of FEL propagation, opening access to nonlinear phenomena and their temporal evolution.

    “Specially designed 1D imaging fluorescence spectrometers, enabling probing of the interaction of a dense molecular target with the intense XUV radiation in the direction of the FEL propagation, open up new and unique access to studies of nonlinear phenomena and their temporal evolution.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    The situation has changed with the development of XFELs and high harmonic based sources capable of delivering femtosecond or even sub-femtosecond x-ray pulses.

    “The situation has changed with the development of XFELs and high harmonic based sources capable of delivering femtosecond or even sub-femtosecond x-ray pulses.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    At shorter wavelengths, general application of direct multiphoton processes is still a challenge, although feasibility and potential have been demonstrated.

    “at shorter wavelength the general application of the direct multiphoton process is still a challenge, although the feasibility and potential has been demonstrated [75][76][77].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [75][76][77]

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    Spatial information from single-shot imaging experiments can be used to investigate particle nucleation and growth processes, morphologies of larger nanoparticle assemblies, exotic symmetries in reduced-dimensional systems, and phase mixes and separations on the nanoscale.

    “The spatial information from single-shot imaging experiments [89,90,92,[93][94][95] can be used to investigate particle nucleation and growth processes, morphologies of larger nanoparticle assemblies, exotic symmetries in reduced-dimensional systems, as well as phase mixes and phase separations on the nanoscale.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [89,90,92,[93][94][95]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Most typical XFEL targets, in particular organic molecules, mainly consist of light elements.

    “most of the typical XFEL targets, in particular, organic molecules, mainly consist of light elements.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The first proof-of-principle experiments for single-shot imaging of single nanometer-sized samples in the gas phase targeted cluster shapes and sizes, morphologies of cluster assemblies, and imaging biological specimens.

    “The first proof-of-principle experiments for single-shot imaging of single nanometer-sized samples in the gas phase (figure 15) were targeted at determining cluster shapes and sizes [92], the morphologies of cluster assemblies [93], and imaging biological specimens [94].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [92] Bostedt C, 2010, J. Phys. B: At. Mol. Opt. Phys. source

      Not checked in the free run.

    • cites [93] Rupp D, 2012, New J. Phys. source

      Not checked in the free run.

    • cites [94] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    THz streaking allows setting a very precise time marker and identifying pulses with subfemtosecond durations, bringing the attosecond regime into reach.

    “The attosecond regime comes into reach through techniques like THz streaking allowing setting a very precise time marker and identifying pulses with subfemtosecond durations [80].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [80] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    The two-photon process explores different Franck-Condon areas and gives access to different molecular geometries and dissociation dynamics.

    “The two-photon process explores, therefore, different Franck-Condon areas and gives access to different molecular geometries and dissociation dynamics.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    HHG pulses are becoming intense enough to not only initiate dynamics but also to efficiently probe reactions driven by a synchronized laser.

    “HHG pulses are becoming intense enough to not only initiate the dynamics, but also to efficiently probe the reactions driven by a synchronized laser.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    High-resolution electron spectroscopy and determination of electron angular distributions for high kinetic energy electrons have been successfully developed.

    “In addition, high-resolution electron spectroscopy and the determination of the electron angular distributions for high kinetic energy electrons have been successfully developed.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    In general, there can be a variety of pathways driving charge dynamics in a core-ionized state.

    “in general, there can be a variety of pathways driving charge dynamics in such a core-ionized state.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Even a single heavy atom constituent can significantly alter total energy deposition in a large macromolecule and cause increased local radiation damage.

    “Under these conditions, even a single heavy atom constituent can significantly alter the total energy deposition in a large macromolecule and cause increased local radiation damage.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Following initial photoabsorption, induced charge and deposited energy can be efficiently redistributed to neighboring atoms.

    “Following this initial photoabsorption step, the induced charge and deposited energy can be efficiently redistributed to the neighboring atoms.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    In atomic multiphoton processes, symmetries of resonances and of outgoing electrons depend on the polarization state of linearly and circularly polarized light.

    “In atomic multiphoton processes, symmetries of resonances and of outgoing electrons depend on the polarization state of the linearly and circularly polarized light.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    Optical light pulses can excite a nanoparticle as a whole, and x-ray pulses can be used to induce localized, element-specific excitations.

    “Optical light pulses can excite the nanoparticle as a whole and x-ray pulses can be used to induce localized, element-specific excitations [101].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [101] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Massively parallel computing models can now describe the complete x-ray induced process from ionization to inner-vacancy decays to elastic and inelastic scattering, and give guidance on optimized imaging parameters.

    “Massively parallel computing models can now describe the complete x-ray induced process from ionization to inner-vacancy decays, to elastic and inelastic scattering processes, and give guidance on optimized imaging parameters [98].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [98] source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Doping superfluid droplets with xenon showed that quantum vortices exist inside the droplets and form lattices with densities up to five orders of magnitude higher than in bulk superfluid helium.

    “Doping the droplets with xenon, which acted akin to an x-ray contrast agent, it was possible to show that quantum vortices exist inside the droplets and that they form lattices with densities up to five orders of magnitude higher than in bulk superfluid helium.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    The time scale of charge rearrangement after inner-shell photoabsorption can vary from sub-femtosecond to a few femtoseconds, depending on the mechanism.

    “The time scale of such a charge rearrangement can vary from sub-femtosecond to a few femtoseconds, depending on the particular mechanism.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    This heavy-atom effect is observable in x-ray diffraction patterns from biological objects containing sulfur, selenium, iodine atoms or heavy metal centers, and can be exploited for phasing of diffraction data.

    “This is observable in the x-ray diffraction patterns from biological objects containing, e.g., sulfur, selenium, and iodine atoms [84], or heavy metal centers, and can be exploited for phasing of the acquired diffraction data [85].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [84] source

      Not checked in the free run.

    • cites [85] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Few-fs transfer dynamics of a double valence hole created by core-shell ionization and Auger decay might be barely accessible with few-fs pulses at LCLS, while sub-fs charge migration is currently beyond reach.

    “while the few-fs transfer dynamics of a double valence hole [88] created by core-shell ionization and subsequent Auger decay might be barely accessible with the few-fs pulses available at the LCLS, sub-fs charge migration discussed in [81] is currently beyond reach.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [88] source

      Not checked in the free run.

    • cites [81] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given

    The European XFEL has a high number of photon pulses, namely 27,000 pulses per second, which is its main and up to now unique characteristic.

    “The main and, up to now, unique characteristic of the European XFEL is the high number of photon pulses, namely 27 000 pulses per second.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    In general, strong correlations affect the electronic structure of multiradical species, which are unavoidably formed when molecules are exposed to high-intensity x-ray pulses.

    “In general, strong correlations affect the electronic structure of multiradical species, which are unavoidably formed when molecules are exposed to high-intensity x-ray pulses.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given

    The HHG process makes it possible to generate light spanning UV to x-ray wavelengths using table-top-scale ultrafast lasers, with unprecedented temporal and spatial coherence.

    “The HHG process makes it possible to generate light spanning UV to x-ray wavelengths using table-top-scale ultrafast lasers, with unprecedented temporal and spatial coherence.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    In the hard x-ray case, the nonlinearly induced current at the second harmonic scales as ω -2 (and thus the polarization as ω -3 ), which for x-ray wavelengths is considerably more efficient than the anharmonicities in the atomic potential.

    “In this case, the nonlinearly induced current at the second harmonic scales as ω -2 (and thus the polarization as ω -3 ), which for x-ray wavelengths is considerably more efficient than the anharmonicities in the atomic potential.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: For interactions with hard x-rays, the electrons in a material can be approximated as quasi-free when the x-ray energy is well above the atomic resonances.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationcitation

    The coincident imaging and spectroscopy approach can be extended to a wide range of applications.

    “The coincident imaging and spectroscopy approach [89] can be extended to a wide range of applications.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [89] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    In HHG, an intense femtosecond laser pulse is focused into a gas to create a nanoscale quantum antenna during the process of strong field ionization, thereby upconverting laser light to much shorter wavelengths.

    “In HHG, an intense femtosecond laser pulse is focused into a gas to create a nanoscale quantum antenna during the process of strong field ionization, thereby upconverting laser light to much shorter wavelengths.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    Compared to systems available to date, detector dynamic range needs to be improved to span more than four orders of magnitude from the intense center of the coherent image to single-photon signal levels at large scattering angles.

    “Compared to the systems available to date the dynamic range needs to be improved to span more than four orders of magnitude from the intense center of the coherent image to the single-photon signal levels at large scattering angles.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    A combination of monochromators and grazing incidence mirrors can be used to effectively suppress the FEL harmonics of the incident beam without dramatically affecting the spectral brightness.

    “A combination of monochromators and grazing incidence mirrors can be used to effectively suppress the FEL harmonics of the incident beam without dramatically affecting the spectral brightness.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    HHG for coherent XUV generation was first described in 1987 [117], with subsequent work clearly showing that HHG is a nonperturbative interaction [118].

    “HHG for coherent XUV generation was first described in 1987 [117], with subsequent work clearly showing that HHG is a nonperturbative interaction [118].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [117] source

      Not checked in the free run.

    • cites [118] Ferray M, 1988, J. Phys. B: At. Mol. Opt. Phys. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    XMDYN is part of the start-to-end simulation package for biomolecular imaging at the European XFEL [114].

    “XMDYN is part of the start-to-end simulation package for biomolecular imaging at the European XFEL [114].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [114] source

      Not checked in the free run.

  • May combine two claims.

    Premisenone given

    For heavier atoms, millions to billions of distinct configurations are accessible, corresponding to millions to billions of rate equations.

    “For heavier atoms, millions to billions of distinct configurations are accessible, corresponding to millions to billions of rate equations.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    In the case of the lowest (second) order nonlinearity, the induced polarization scales as ω -6 for frequencies well above atomic resonances.

    “In the case of the lowest (second) order nonlinearity, the induced polarization scales as ω -6 for frequencies well above atomic resonances.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given

    The efficiency of Bragg experiments from nanoparticles in the gas phase is low because particles only stochastically satisfy the Bragg condition, and most of the time only incomplete reflections and partial cuts of the Ewald sphere are recorded.

    “The efficiency of Bragg experiments from nanoparticles in the gas phase is low, however, as the particles only stochastically satisfy the Bragg condition, and most of the time only incomplete reflections and partial cuts of the Ewald sphere are recorded.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    The dynamics of the HHG process itself represent the inception of attosecond science, where sub-optical cycle dynamics drives the physics, and the physics intrinsically drives the HHG process toward shorter, rather than longer, pulses.

    “However, the implications have been profound-the dynamics of the process itself not only represent the inception of attosecond science [125, 126], where sub-optical cycle dynamics drives the physics, but also where the physics intrinsically drives the HHG process toward shorter, rather than longer, pulses.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [125] source

      Not checked in the free run.

    • cites [126] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Because x-rays interact predominantly with the electronic degrees of freedom of matter, high-intensity x-ray science presents electronic-structure theorists with unprecedented challenges.

    “Because x-rays interact predominantly with the electronic degrees of freedom of matter (in a way that ultimately affects outer-shell electrons as much as it affects inner-shell electrons), high-intensity x-ray science presents electronic-structure theorists with unprecedented challenges.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given

    The resolution obtainable in state-of-the-art single-shot imaging experiments is currently limited by signal levels at large scattering angles, and so is the lower sample size limit.

    “The resolution obtainable in state-of-the-art single-shot imaging experiments is currently limited by the signal levels at large scattering angles, and so is the lower sample size limit.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisereasoning

    For the free-electron nonlinearity, the number of scattered photons per unit timescales as ω -3 for a fixed field strength, which leads to a factor of 10 -12 smaller efficiencies for 10 keV x-rays compared to 1 eV optical photons.

    “Still, for the free-electron nonlinearity, the number of scattered photons per unit timescales as ω -3 for a fixed field strength, which leads to a factor of 10 -12 smaller efficiencies for 10 keV x-rays compared to 1 eV optical photons.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: For interactions with hard x-rays, the electrons in a material can be approximated as quasi-free when the x-ray energy is well above the atomic resonances.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Isolated attosecond pulse generation is a special case where the emission is confined to a single peak in the laser field [121, 122], although all HHG emission occurs in attosecond bursts.

    “Isolated attosecond pulse generation is a special case where the emission is confined to a single peak in the laser field [121, 122], although all HHG emission occurs in attosecond bursts.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [121] source

      Not checked in the free run.

    • cites [122] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    In single-shot x-ray scattering experiments for biomolecular imaging, the x-ray absorption per nonhydrogen atom is practically saturated.

    “In such experiments, single-shot x-ray scattering patterns are recorded under conditions in which the x-ray absorption per nonhydrogen atom is practically saturated.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    The x-ray response of interacting many-electron systems governs the structure and dynamics of matter exposed to high-intensity x-rays.

    “The importance of the electronic-structure problem in this context derives from the fact that the x-ray response of interacting many-electron systems governs the structure and dynamics of matter exposed to high-intensity x-rays.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    The nonlinearities in dielectric materials at optical wavelengths are mainly due to anharmonicity in the atomic potential.

    “The nonlinearities in dielectric materials at optical wavelengths are mainly due to anharmonicity in the atomic potential.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Premisenone given

    Spectroscopy fundamentally relies on the availability of quantitatively accurate theory.

    “Spectroscopy fundamentally relies on the availability of quantitatively accurate theory.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    In contrast to small gas-phase systems, intramolecular impact ionization by photoelectrons and Auger electrons is particularly important.

    “Moreover, in contrast to small gas-phase systems, intramolecular impact ionization by photoelectrons and Auger electrons is particularly important.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The scattering signal is generated during the pulse, so the obtainable temporal resolution is only limited by the imaging pulse length.

    “The scattering signal is generated during the pulse and therefore the obtainable temporal resolution is only limited by the imaging pulse length.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Recent FEL experiments have demonstrated the possibility of driving nonlinear effects at hard x-ray wavelengths.

    “Recent FEL experiments have demonstrated the possibility of driving nonlinear effects at hard x-ray wavelengths.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Because of the currently operational XFELs with comparably low repetition rates of ∼100 Hz, nonlinear experiments need to be performed at x-ray intensities near or above the sample damage threshold and typically using solid samples with a sufficiently high electron density.

    “Because of the currently operational XFELs with comparably low repetition rates of ∼100 Hz, nonlinear experiments need to be performed at x-ray intensities near or above the sample damage threshold and typically using solid samples with a sufficiently high electron density.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Interpretationnone given

    The central challenge for electronic-structure theory in connection with XFELs is the quantitative treatment of the radiation-driven dynamics of polyatomic systems.

    “The central challenge for electronic-structure theory in connection with XFELs is the quantitative treatment of the radiation-driven dynamics of polyatomic systems.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    The figure of merit for single-shot imaging is not necessarily the highest number of photons but the highest number of photons per Auger lifetime.

    “In this context it is noted that the figure of merit is not necessarily the highest number of photons but the highest number of photons per Auger lifetime.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The high-energy collision process in HHG is fully coherent, resulting in coherent dipole emission from each atom.

    “As such, the high-energy collision process is fully coherent, resulting in coherent dipole emission from each atom.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    While nonlinearities are considerably smaller at x-ray wavelengths than in the optical regime, they offer new possibilities for understanding structure and dynamics at the atomic scale due to their short wavelength.

    “While nonlinearities are considerably smaller at x-ray wavelengths than in the optical regime, they offer new possibilities for understanding structure and dynamics at the atomic scale due to their short wavelength.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Because of space-charge effects, only a fraction of all ionized electrons manage to escape from the system.

    “In addition, because of space-charge effects, only a fraction of all ionized electrons manage to escape from the system.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given

    The single-shot imaging process is always a strong probe and will strongly interfere with the sample itself.

    “On a final note it is important to remember that the single-shot imaging process is always a strong probe and will also strongly interfere with the sample itself.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Both resolution and lower sample size limit can be improved through higher exposure intensities, i.e., higher photon output of the laser, efficient beam transport to the sample, and tighter foci.

    “Both aspects can be improved through higher exposure intensities of the sample, i.e. higher photon output of the laser, efficient beam transport to the sample, and tighter foci.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    The bottleneck for all types of table-top laser driven x-ray sources has always been the achieved flux and photon energy.

    “The bottleneck for all types of table-top laser driven x-ray sources has always been the achieved flux and photon energy.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Although HHG can, in principle, provide usable sources into the soft- and even hard x-ray region of the spectrum, actual implementation will be a continued technological challenge.

    “Although we know that HHG can, in principle, provide usable sources into the soft-and even hard x-ray region of the spectrum, actual implementation will be a continued technological challenge.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisenone given

    Amplifying few-cycle pulses is a major challenge in ultrafast optics because most amplifiers introduce gain narrowing leading to spectral losses.

    “Amplifying these few-cycle pulses represents a major challenge in ultrafast optics as most amplifiers introduce gain narrowing leading to spectral losses.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The current Fourier plane can be further upscaled in dimension to allow a Joule level of pumping to reach 10 TW few-cycle pulses.

    “The current Fourier plane can be further upscaled in dimension to allow a Joule level of pumping to reach 10 TW few-cycle pulses.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationnone given

    These laser developments are the most promising tools to scale HHG-based soft x-ray sources with attosecond pulse duration.

    “These are the most promising tools to scale such HHG-based soft x-ray sources with attosecond pulse duration.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Commercial table-top EUV light sources can now generate a coherent flux comparable to synchrotrons, with much higher peak brightness and intrinsic synchronization to a femtosecond laser [138].

    “Another significant recent advance is that commercial table-top EUV light sources can now generate a coherent flux comparable to synchrotrons-with much higher peak brightness and intrinsic synchronization to a femtosecond laser [138].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [138]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    To date, at least in the US, the potential of table-top coherent x-ray technology has yet to be acknowledged in a concerted way by the funding agencies.

    “To date, at least in the US, this potential has yet to be acknowledged in a concerted way by the funding agencies.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Mid-IR ultrafast lasers are typically implemented through parametric down conversion (PDC) from shorter wavelengths.

    “Mid-IR ultrafast lasers are typically implemented through parametric down conversion (PDC) from shorter wavelengths.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The unique combination of quantum coherence and macroscopic physics has made it possible both to optimize emission to a particular harmonic order using pulse shaping [126], and to generate the smooth supercontinuum spectrum of a single attosecond burst [135, 136].

    “The unique combination of quantum coherence and macroscopic physics has made it possible both to optimize emission to a particular harmonic order using pulse shaping [126], and to generate the smooth supercontinuum spectrum of a single attosecond burst [135, 136].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [126] source

      Not checked in the free run.

    • cites [135] source

      Not checked in the free run.

    • cites [136] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The current status of HHG as a light source is that we have good predictive power over optimization of HHG for simple phase matching in weakly ionized gases; optimally, the peak intensity of the focused beam should drive the ionization to the 'critical' (phase-matched) ionization level at the peak of the pulse [128,131,132].

    “The current status of HHG as a light source is that we have good predictive power over optimization of HHG for simple phase matching in weakly ionized gases; optimally, the peak intensity of the focused beam should drive the ionization to the 'critical' (phase-matched) ionization level at the peak of the pulse [128,131,132].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [128] source

      Not checked in the free run.

    • cites [131]

      Not checked in the free run.

    • cites [132] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Interpretationnone given

    These techniques are still too difficult for truly routine implementation in complex application experiments.

    “However, these techniques are still too difficult for truly routine implementation in complex application experiments.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The lifetime of highly excited states in solids can be directly measured, confirming 'final state' effects in photoemission spectroscopy [142].

    “The lifetime of highly excited states in solids can be directly measured, confirming 'final state' effects in photoemission spectroscopy [142].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [142] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given

    The peak intensity requirement for HHG is approximately constant while the spot size for a given confocal parameter of the laser increases.

    “However, the peak intensity requirement for HHG is approximately constant while the spot size for a given confocal parameter of the laser increases.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The ultrafast scientific community has widely adopted the femtosecond titanium-sapphire laser based on chirped-pulse amplification.

    “Despite the progress with CO 2 lasers, the ultrafast scientific community has widely adopted the femtosecond titanium-sapphire (Ti-Sa) laser based on the chirped-pulse amplification (CPA) technique [147].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [147] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Ti-Sa lasers successfully drive secondary sources of photons and particles, making the spectral range from THz to hard x-rays available via nonlinear optical processes.

    “Ti-Sa lasers successfully drive secondary sources of photons and particles; using a variety of nonlinear optical processes, the spectral range from the THz [149] to hard x-rays becomes available.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [149] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    HHG calculations represent a combination of atomic quantum dynamics with macroscopic electromagnetic propagation, with the scale lengths spanning many orders of magnitude.

    “HHG calculations represent an elegant combination of atomic quantum dynamics with macroscopic electromagnetic propagation, with the scale lengths spanning many orders of magnitude.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Interpretationreasoning

    This does not preclude isolated attosecond bursts, as the physics naturally drives the process in this direction.

    “Importantly, this does not preclude isolated attosecond bursts, as the physics naturally drives the process in this direction .”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    The ultimate high-energy limit for the HHG process has not yet been identified.

    “Finally, the ultimate high-energy limit for the HHG process has not yet been identified.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    Since the ponderomotive energy (Up) of charged particles in a laser field scales with the square of the laser wavelength, intense CO 2 sources near 10 μm provide the capability to build compact, high-energy accelerators.

    “Since the ponderomotive energy (Up) of charged particles in a laser field scales with the square of the laser wavelength, intense CO 2 sources near 10 μm provide the capability to build compact, high-energy accelerators.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing). May combine two claims.

    Premisecitation

    The generation of new polarization states represents new physics as well as an enabler for many applications [133,134].

    “Third, the generation of new polarization states represents new physics as well as an enabler for many applications [133,134].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [133] source

      Not checked in the free run.

    • cites [134] source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    The focus region must sustain constant intensity over a propagation length corresponding to several absorption lengths of the generated light, and the gas region must end abruptly before the laser intensity decreases significantly.

    “The focus region must sustain this (constant) intensity over a propagation length corresponding to several absorption lengths of the generated light, and the gas region must end abruptly before the laser intensity decreases significantly.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    The use of OPAs has opened new research avenues in strong-field laser science and provided a unique tool to scale the HHG cut-off, generating ultrashort soft x-ray pulses up to the 1 keV range.

    “The use of these OPAs has opened new research avenues in strong-field laser science, but has also provided a unique tool to scale the HHG cut-off, and thus to generate ultrashort soft x-ray pulses up to the 1 keV range of photon energies (see sections 5.1 and [129]).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [129] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationreasoning

    Given the large bandwidth of attosecond pulses, a multitude of processes are simultaneously excited and probed in an attosecond experiment, requiring a high-energy physics approach to isolate the dynamics of interest.

    “Given the large bandwidth of attosecond pulses, a multitude of processes are simultaneously excited and probed in an attosecond experiment, requiring a 'high-energy physics' approach to isolate the dynamics of interest.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    This has permitted two novel capabilities: driving nonlinear ionization/excitation processes and using HHG pulses for single-shot CDI measurements.

    “This has permitted the emergence of two significant and novel capabilities, namely (1) the ability to drive nonlinear ionization/excitation processes (i.e.laser-matter interactions where the sample absorbs more than one photon), and (2) the ability to use the HHG pulses for single-shot CDI measurements.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    This allows experiments where XUV absorption of selected atoms is used as a site-specific detector for particular electronic processes.

    “This allows experiments where XUV absorption of selected atoms is used as a site-specific 'detector' for particular electronic processes of interest.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given

    Application of HHG radiation in pump-probe experiments remained rare for more than a decade due to unsolved technical problems.

    “Although the potential benefits of HHG radiation for time-resolved spectroscopy were immediately realized, the application of HHG radiation in pump-probe experiments remained rare for more than a decade due to a number of unsolved technical problems that frustrated successful implementation.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    Many benefits of HHG are increasingly being exploited in femtosecond time-resolved experiments beyond attosecond science.

    “Many of the benefits of HHG that were discussed above are beneficial beyond attosecond science, and are increasingly being exploited in femtosecond time-resolved experiments.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Almost all work in attosecond science up to now has been achieved using relatively standard, commercially available femtosecond laser amplifiers.

    “Almost all the work in attosecond science up to now has been achieved using relatively standard, commercially available femtosecond laser amplifiers.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisereasoning

    The main challenge at the horizon of 2020 consists in scaling the average power of few-cycle MIR lasers.

    “To enable this forefront science, the main challenge at the horizon of 2020 consists in scaling the average power of few-cycle MIR lasers.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Scaling the wavelength of the driver laser used in HHG has recently allowed increasing the high-energy cut-off of HHG spectra, and research groups are beginning to use broadband XUV continua extending into the water window.

    “Scaling of, in particular, the wavelength of the driver laser used in the HHG process has recently allowed increasing the high-energy cut-off of HHG spectra [129], and these days an increasing number of research groups are beginning to use extremely broadband XUV continua that extend into the water window, i.e. the wavelength region where light elements like C, N and O have their K-edges”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [129] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    The 3.9 μm 20 Hz OPCPA suffers from low average power but offers the opportunity of scaling its repetition rate using a recently developed high average power Yb ps laser system.

    “While this MIR laser suffers from low average power, it offers the unique opportunity of scaling its repetition rate using a recently developed high average power Yb ps laser system.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    This triggered theoretical studies of this interaction and of the effect of probing the system.

    “This also triggered theoretical studies of this interaction as well as of the effect of probing the system [187,190,194].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [187] source

      Not checked in the free run.

    • cites [190] source

      Not checked in the free run.

    • cites [194] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    HHG has been, up to now, the only technique capable of producing attosecond laser pulses that can be used in pump-probe experiments.

    “Although this may soon change, HHG has been, up to now, the only technique capable of producing attosecond laser pulses that can be used in pumpprobe experiments.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    More recent experiments have addressed correlated two-electron dynamics, attosecond to few-femtosecond charge migration in molecules, and electric field-induced charge separation in solids.

    “More recent experiments have addressed correlated two-electron dynamics [169], attosecond to few-femtosecond charge migration in molecules [170, 171] and electric field-induced charge separation in solids [172].”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [169] source

      Not checked in the free run.

    • cites [170] source

      Not checked in the free run.

    • cites [171] source

      Not checked in the free run.

    • cites [172] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationnone given

    Today, lab-scale HHG sources are extremely versatile and powerful sources usable in many ways, complementing synchrotrons and free-electron lasers.

    “Today, lab-scale HHG sources have developed into extremely versatile and powerful sources that can be used in a multitude of different ways as shown in figure 20, complementing research efforts that are undertaken in synchrotrons and free-electron lasers.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    HHG was discovered in the late 1980s in experiments targeting the role of intermediate resonances in strong-field multiphoton ionization.

    “HHG was discovered in the late 1980s, in the course of experiments targeting a better understanding of the role of intermediate resonances in strong-field multiphoton ionization [165].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [165] Ferray M, 1988, J. Phys. B: At. Mol. Opt. Phys. source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    This led to substantial progress in generation, characterization, and application of attosecond laser pulses and, consequently, in application of HHG radiation in general.

    “This led to substantial progress, not only regarding the generation, characterization and application of attosecond laser pulses, but, as a consequence, regarding the application of HHG radiation in general.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    High-energy MIR lasers are ideal for direct electron acceleration to generate sub-cycle electron bunches and incoherent sub-100 fs hard x-ray pulses for ultrafast diffraction imaging.

    “Furthermore, high-energy MIR lasers are also ideal for direct electron acceleration to generate sub-cycle electron bunches [162] and incoherent sub-100 fs hard x-ray pulses [163] for ultrafast diffraction imaging.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [162] source

      Not checked in the free run.

    • cites [163] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Premisenone given

    Attosecond pulses generated by HHG inherently operate in the XUV/x-ray wavelength domain, where photoabsorption becomes increasingly core-level specific and atom-specific.

    “attosecond pulses generated by HHG inherently operate in the XUV/x-ray wavelength domain, the domain where photoabsorption becomes increasingly core-level specific (and hence atom-specific).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    THz pulses provide a unique tool to control fundamental properties of matter, such as magnetization, ferroelectricity, and optical properties.

    “Two of the envisioned experiments are: (i) THz pulses provide a unique tool to control the fundamental properties of matter, such as magnetization, ferroelectricity, and optical properties.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Pump/probe schemes often use either single attosecond pulses with a rather intense infrared probe pulse or an attosecond pulse train with a weak infrared pulse.

    “Pump/probe schemes often use either single attosecond pulses together with a rather intense infrared probe pulse [185,186,191] or an attosecond pulse train together with a weak infrared pulse [187-190, 192, 193].”
    Quote in the paperNot a substantial claim0 of 9 sources checked
    • cites [185] source

      Not checked in the free run.

    • cites [186] source

      Not checked in the free run.

    • cites [191] source

      Not checked in the free run.

    • cites [187] source

      Not checked in the free run.

    • cites [188] source

      Not checked in the free run.

    • cites [189] Palatchi C, 2014, J. Phys. source

      Not checked in the free run.

    • cites [190] source

      Not checked in the free run.

    • cites [192] source

      Not checked in the free run.

    • cites [193] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    Ti-Sa lasers are not suitable to generate high-energy pulses above 2.5 μm with high average power, so a technology change is required.

    “Ti-Sa lasers are simply not suitable to generate high-energy pulses above 2.5 μm, with high average power, so a technology change is required.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisereasoning

    The initial ionization step in the three-step picture depends highly nonlinearly on the laser electric field, producing electron bunches much shorter than the driver laser optical cycle (2.7 fs for Ti:Sa).

    “The initial ionization step in the three-step picture depends highly nonlinearly on the laser electric field, and hence produces bunches of electrons with a duration much shorter than the duration of the driver laser optical cycle (2.7 fs for a Ti:Sa laser).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Important breakthroughs have been achieved in both branches of attosecond spectroscopy, as summarized in recent reviews.

    “In both branches, important breakthroughs have been achieved, as summarized in recent reviews [198,199].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [198] Marangos J P, 2016, J. Phys. B: At. Mol. Opt. Phys. source

      Not checked in the free run.

    • cites [199] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    This challenge has been addressed by extensive computational work but will impose a limit on complexity of samples that can be investigated in the future.

    “This challenge has been addressed by extensive computational work in the past (see e.g.[170, 171]), but will clearly impose a limit on the complexity of the samples that can be investigated in the future.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [170] source

      Not checked in the free run.

    • cites [171] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    An electronic ionized wavepacket created by absorbing an attosecond pulse acquires a group delay when propagating through the atomic (or molecular) potential.

    “Similarly, an electronic ionized wavepacket created by absorbing an attosecond pulse acquires a group delay when propagating through the atomic (or molecular) potential.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    High-harmonic sources extended to soft x-ray domain are in principle capable of achieving attosecond durations and provide pulses perfectly synchronized with driving laser pulse.

    “High-harmonic sources, which are being extended to the soft x-ray domain [129, 202, 203], are in principle clearly capable of achieving attosecond durations and provide pulses that are perfectly synchronized with the driving laser pulse.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [129] source

      Not checked in the free run.

    • cites [202] source

      Not checked in the free run.

    • cites [203] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisenone given

    The two main branches of attosecond spectroscopy are pump-probe measurements combining attosecond pulses with NIR femtosecond pulses and high-harmonic spectroscopy exploiting HHG to record attosecond dynamics in the generation medium.

    “The two main branches of attosecond spectroscopy are (i) pump-probe measurements combining attosecond pulses with near-infrared femtosecond pulses and (ii) high-harmonic spectroscopy, which exploits the mechanism of HHG to record attosecond dynamics taking place in the generation medium.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    FELs are much more intense but struggle to achieve very short pulse durations and good temporal synchronization with laser pulses.

    “FELs are much more intense, but struggle to achieve very short pulse durations, as well as a good temporal synchronization with laser pulses.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Frequency-domain spectroscopy of complex systems is often realized in the x-ray domain because short-wavelength radiation gives access to inner shells with element-specific binding energies.

    “This challenge is one reason why frequency-domain spectroscopy of complex systems is often realized in the x-ray domain [201].Short-wavelength radiation gives access to inner shells that have element-specific binding energies.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [201] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Moving attosecond spectroscopy from gas phase to liquid phase represents a huge challenge but is necessary to understand dynamics of molecules in their natural environment, which differ from isolated gas-phase molecules.

    “Moving attosecond spectroscopy from the gas phase to the liquid phase represents a huge challenge.It is, however, necessary to obtain the information required to understand the dynamics of molecules in their natural environment, which will in general significantly differ from that of isolated molecules in the gas phase.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Interpretationreasoning

    The door is now open to investigation of more complex problems such as dynamics of electrons in inner shells or migration of charge in molecules.

    “The door is now open to the investigation of more complex problems such as the dynamics of electrons in inner shells or the migration of charge in molecules.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisenone given

    Technical challenges include precision and stability of the optical interferometer, laser repetition rate affecting measurement length and reliability, available spectral range, and resolution of the electron spectrometer.

    “To these challenges, which are coupled to the physics of the measurements, we should add more technical challenges related to the precision and stability of the optical interferometer, the laser repetition rate, which affects the length (and therefore reliability) of the measurements, the available spectral range and the resolution of the electron spectrometer.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    In this spectral region, spectroscopy is complicated by high density of molecular valence states and challenging interpretation due to delocalized electronic wave functions.

    “In this spectral region spectroscopy is complicated by the high density of molecular valence states and its interpretation is challenging due to the delocalized nature of the associated electronic wave functions.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Our measurement utilizes a two-photon ionization process.

    “The next challenge is that our measurement utilizes a two-photon ionization process.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Most recently, attosecond photoionization delays have been measured in molecules and high-harmonic spectroscopy has been developed to reconstruct charge migration in spatially oriented molecules on attosecond timescales.

    “Most recently, attosecond photoionization delays have been measured in molecules [200] and highharmonic spectroscopy has been developed further to reconstruct charge migration in spatially oriented molecules on attosecond timescales [171].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [200] source

      Not checked in the free run.

    • cites [171] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    All fundamental advances in attosecond science have so far been realized in the XUV.

    “All of the fundamental advances in attosecond science have so far been realized in the XUV.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning

    Extension of attosecond spectroscopy to the x-ray domain appears to be the most promising future direction in this area.

    “An extension of attosecond spectroscopy to the x-ray domain therefore appears to be the most promising future direction in this area of research.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductreasoning

    This challenge is circumvented by performing two measurements simultaneously and taking the difference, eliminating τXUV because the same excitation pulses are used for ionization from the two subshells.

    “This is a major challenge, which we circumvent by performing two measurements simultaneously and taking the difference, as done in figure 22.As we use the same excitation pulses for ionization from the two subshells, τ XUV is eliminated.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    One of the most interesting applications of attosecond pulse technology is the possibility to measure phases (or phase derivatives, i.e. delays) of quantum mechanical probability amplitudes.

    “One of the most interesting applications of attosecond pulse technology is the possibility to measure phases (or phase derivatives, i.e. delays) of quantum mechanical probability amplitudes.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given

    Understanding attosecond dynamics of electrons in isolated molecules is an important first step, still far from fully realized.

    “Understanding the attosecond dynamics of electrons in isolated molecules is an important first step, which is still far from being fully realized.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based). May combine two claims.

    Interpretationnone given

    An even more important goal is to understand dynamics of molecules in solution, where most chemical and biophysical processes take place.

    “Nevertheless, an even more important goal is to understand the dynamics of molecules in solution, where most chemical and biophysical processes take place.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Such measurements allow complete characterization of electron wavepackets in spectral or temporal domain, giving access to temporal dynamics.

    “Such measurements allow us to completely characterize electron wavepackets in the spectral or temporal domain, giving thus access to the temporal dynamics.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given

    Core-hole lifetimes are at the heart of many short time dynamical processes, and those timescales could stymie the desired goals of obtaining ultrashort electronic timescales in molecules and solids.

    “Core-hole lifetimes are at the heart of many short time dynamical processes, and those timescales could stymie the desired goals of obtaining ultrashort electronic timescales in molecules and solids.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Since that time, many researchers have adopted the transient-absorption technique as a favored method for probing dynamics.

    “Since that time, many researchers have adopted the transient-absorption technique as a favored method for probing dynamics.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

    Premisenone given

    Pump-probe transient spectroscopies are simply the most basic version of measurements made in the optical region.

    “Pump-probe transient spectroscopies are simply the most basic version of measurements made in the optical region.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The work described in [6] illustrates how the molecule breaks apart and what ionic fragments are formed via the breakage of the molecular edifice shortly after the inner-shell ionization, shedding light on the role of energetic ions in the initiation of damaging reactions.

    “The work described in [6] illustrates how the molecule breaks apart and what ionic fragments are formed via the breakage of the molecular edifice shortly after the inner-shell ionization, shedding light on the role of energetic ions in the initiation of damaging reactions.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [6] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Instruments at several locations are seeking the requisite pulse energies of about 1 μJ to 1 mJ.

    “Instruments at several locations are seeking the requisite pulse energies of about 1 μJ to 1 mJ.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Premisecitation

    While tantalizing results are emerging, charge migration in molecules, materials, and across junctions represents a grand challenge of the attosecond field.

    “While tantalizing results are emerging, charge migration [170] in molecules, materials, and across junctions represents a grand challenge of the attosecond field.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [170] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The lifetime of highly excited states in solids can be directly measured, confirming 'final state' effects in photoemission spectroscopy.

    “The lifetime of highly excited states in solids can be directly measured, confirming 'final state' effects in photoemission spectroscopy[142].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [142] source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Time decays can be obtained for autoionization processes, and even high-resolution spectroscopic information is acquired from the coherent superpositions of electronic and vibrational states.

    “Time decays can be obtained for autoionization processes, and even high-resolution spectroscopic information is acquired from the coherent superpositions of electronic and vibrational states.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given

    The extreme bandwidth of the XUV pulses also requires creative solutions to resolve spectral features.

    “The extreme bandwidth of the XUV pulses also requires creative solutions to resolve spectral features.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    The real part of the dielectric function can derive information about the renormalization of the Coulomb potential after photoexcitation (polarization), while the imaginary part shows the increase or decrease of loss channels, i.e. changes in absorption.

    “The real part of the dielectric function can derive information about the renormalization of the Coulomb potential after photoexcitation (polarization), while the imaginary part shows the increase or decrease of loss channels, i.e. changes in absorption.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Premisecitation

    Multidimensional spectroscopies remain an important goal of the field to peer beneath broadened and obscured spectral features with coherent methods.

    “Multidimensional spectroscopies [223] remain an important goal of the field to peer beneath broadened and obscured spectral features with coherent methods.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [223] source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Core-level transient-absorption spectroscopy is a method that is element specific, and sensitive to oxidation states and spin states, and is applicable to a wide range of chemical elements and species.

    “Core-level transient-absorption spectroscopy [215], a method that is element specific, and sensitive to oxidation states and spin states, is applicable to a wide range of chemical elements and species.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [215] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Premisenone given

    Despite the successes with transient-absorption and photoelectron streaking methods, there are many desirable scientific goals that have not yet been attained.

    “Despite the successes with transient-absorption and photoelectron streaking methods, there are many desirable scientific goals that have not yet been attained.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    By selecting a nonintuitive order of the pump and probe pulses, i.e. introducing the XUV pulse first, superpositions of electronic and vibrational states can be created, which are probed as they evolve in time by using time-delayed optical pulses that modify the polarization of the medium via coupling to neighboring states.

    “By selecting a nonintuitive order of the pump and probe pulses, i.e. introducing the XUV pulse first, superpositions of electronic and vibrational states can be created, which are probed as they evolve in time by using time-delayed optical pulses that modify the polarization of the medium via coupling to neighboring states [212].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [212] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    Measuring important electron dynamical timescales, attosecond science is the next breakthrough technology beyond femtosecond spectroscopy, which was often limited to the slower motions of nuclei.

    “Measuring important electron dynamical timescales, attosecond science is the next breakthrough technology beyond femtosecond spectroscopy, which was often limited to the slower motions of nuclei.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    The broad bandwidth of HHG sources is optimally exploited in energy-dispersed transient absorption because the observed linewidth is only limited by the lifetime of the final state of the x-ray transition.

    “The broad bandwidth of HHG sources is optimally exploited in energy-dispersed transient absorption because the observed linewidth is only limited by the lifetime of the final state of the x-ray transition.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Transient-absorption measurements at synchrotrons and in laboratory table-top systems in the XUV and x-ray were developed first, and the method was only applied to attosecond transient absorption in 2010.

    “Transient-absorption measurements at synchrotrons and in laboratory table-top systems in the XUV and x-ray were developed first, and the method was only applied to attosecond transient absorption in 2010 [222].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [222] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationreasoning

    Borrowing from important principles of core-level spectroscopy at synchrotrons, the field can address oxidation states, spin, and element specificity, with shorter timescales than previously possible.

    “Borrowing from important principles of core-level spectroscopy at synchrotrons, the field can address oxidation states, spin, and element specificity, with shorter timescales than previously possible.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    While short pulses are achievable in the XUV and x-ray portions of the spectrum, the fluxes are usually extremely weak.

    “While short pulses are achievable in the XUV and x-ray portions of the spectrum, the fluxes are usually extremely weak.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [221] Leone S R, 2014, Nat. Photonics source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S4 (based).

    Interpretationnone given

    Recent progress in HHG- and FEL-based light sources has tremendously advanced ultrafast science.

    “Recent progress in HHG-and FELbased light sources has tremendously advanced ultrafast science.”
    Quote in the paperNot a substantial claim
229 of 229

  • The paper relies on this without support.

    Most XFELs are based upon self-amplified spontaneous emission (SASE) radiation, lack longitudinal coherence, struggle to obtain pulse lengths shorter than a few femtoseconds and struggle to synchronize with external sources.

    “Most XFELs are based upon self-amplified spontaneous emission (SASE) radiation, lack longitudinal coherence, struggle to obtain pulse lengths shorter than a few femtoseconds and struggle to synchronize with external sources.”

  • The paper relies on this without support.

    HHG sources have exquisite temporal coherence and pulse duration, but are challenged to obtain large photon numbers per pulse, to extend their reach to short wavelengths and to obtain high average power.

    “HHG sources, on the other hand, have exquisite temporal coherence and pulse duration, but are challenged to obtain large photon numbers per pulse, to extend their reach to short wavelengths and to obtain high average power.”

  • The paper relies on this without support.

    XFEL facilities can provide x-ray pulses with durations down to a few femtoseconds.

    “The XFEL facilities can provide x-ray pulses with durations down to a few femtoseconds.”

  • The paper relies on this without support.

    Producing pulses of duration below a femtosecond is technically feasible.

    “Producing pulses of duration below a femtosecond is also technically feasible.”

  • The paper relies on this without support.

    Focused intensities up to 10^20 W cm^-2 or more permit nonlinear studies, and the high peak fluence enables single-shot diffraction based on the principle of 'diffract before destroy.'

    “Focused intensities up to 10 20 W cm -2 or more permit nonlinear studies, and the high peak fluence enables single-shot diffraction based on the principle of 'diffract before destroy.'”

  • The paper relies on this without support.

    Core energy levels are highly element specific.

    “Since core energy levels are highly element specific, this technique can provide structural and dynamical information with high spatial, temporal, and spectral resolutions not feasible with optical pulses.”

  • The authors state this as an assumption.

    Larger chemical shifts than with single core hole states are expected for double core hole states.

    “Double core hole (DCH) states have recently received growing interest, mainly because larger chemical shifts than with single core hole states are expected.”

  • The paper relies on this without support.

    The effect of nuclear wavepacket propagation on the first excited states in a time shorter than one femtosecond plays a crucial role in the ultrafast fragmentation observed.

    “One of the challenges is to control ultrafast fragmentation in the sub-femtosecond time scale; the effect of the nuclear wavepacket propagation on the first excited states in a time shorter than one femtosecond plays a crucial role in the ultrafast fragmentation observed.”

  • The paper relies on this without support.

    The future of research in this field very much depends on optical issues, synchrotron facilities upgrades and technical improvements of end-stations.

    “The future of research in this field very much depends on optical issues, synchrotron facilities upgrades and technical improvements of end-stations.”

  • The paper relies on this without support.

    The probability for fluorescent decay in the soft x-ray range is below 1%.

    “Unfortunately, the probability for fluorescent decay in the soft x-ray range is below 1%, and this represents a challenge for signal detection.”

  • The authors state this as an assumption.

    For interactions with hard x-rays, the electrons in a material can be approximated as quasi-free when the x-ray energy is well above the atomic resonances.

    “For interactions with hard x-rays, the electrons in a material can be approximated as quasi-free when the x-ray energy is well above the atomic resonances.”

  • The authors state this as an assumption.

    Within XMDYN, neutral atoms, atomic ions, and ionized electrons are treated as classical point particles.

    “Within this framework, neutral atoms, atomic ions, and ionized electrons are treated as classical point particles.”

  • The authors state this as an assumption.

    The force between a pair of charged particles is simply Coulombic; the force between two neutral atoms, or between a neutral atom and an atomic ion, is parametrized as in classical force-field calculations.

    “The force between a pair of charged particles is simply Coulombic; the force between two neutral atoms, or between a neutral atom and an atomic ion, is parametrized as in classical force-field calculations.”

  • The authors state this as an assumption.

    The ionization dynamics of the atoms in XMDYN are treated stochastically by using bound-electron-configuration-dependent cross sections and rates computed with XATOM.

    “The ionization dynamics of the atoms are treated stochastically by using bound-electronconfiguration-dependent cross sections and rates computed with XATOM.”

  • The authors state this as an assumption.

    In the small energy region considered in figure 23, both τXUV and τcc are constant and do not affect the measurement of the phase variation.

    “In the small energy region considered in figure 23, both τ XUV and τ cc can be assumed to be constant and do not affect the measurement of the phase variation.”

  • The authors state this as an assumption.

    One of the photoionization delays can be sufficiently accurately calculated to serve as an absolute reference.

    “except if we assume that one of the delays can by sufficiently accurately calculated to serve as an absolute reference [186].”

  • The paper relies on this without support.

    Water is highly transmissive in the water window.

    “because water is highly transmissive in the water window where the absorption edges of carbon (284 eV) and nitrogen (410 eV) lie.”

  • The paper relies on this without support.

    The conversion efficiency obtained at 3.9 μm of ∼5% can be maintained at 500 Hz to reach a 50 mJ class MIR laser based on existing Yb laser technologies.

    “Considering the recent conversion efficiency obtained at 3.9 μm of ∼5%, a 50 mJ class MIR laser at 500 Hz is reachable based on existing Yb laser technologies.”
18 of 18

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Developments in experimental techniques such as ultrafast spectroscopy, single molecule spectroscopy, time-resolved microscopy and single particle imaging have enabled study of biological dynamics on increasingly small length and time scales, revealing processes necessary for living function that depend on a delicate interplay between quantum and classical physical effects.

    “Recently, developments in experimental techniques such as ultrafast spectroscopy [6], single molecule spectroscopy [7 -11], timeresolved microscopy [12 -14] and single particle imaging [15 -18] have enabled us to study biological dynamics on increasingly small length and time scales, revealing a variety of processes necessary for the function of the living system that depend on a delicate interpl”

    From The future of quantum biology (2018) · cites this paper as [13]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Same cited article has conflicting journal details

    Minor

    References [122] and [135] list the same authors, year, and title, but give different Nature volumes and pages.

  • Same atomic-laser article has different first authors

    Minor

    References [60] and [68] give the same article title, year, journal, volume, and starting page, but identify different first authors.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 6

  1. Larsson M, 2015, 2015 Nobel Symp. Free Electron Laser Res.
  2. 10.1103/PhysRevLett.115.193003 · DOI · Paper page
  3. 10.1038/nature14894 · DOI · Paper page
  4. 10.1126/sciadv.1500837 · DOI · Paper page
  5. 10.1038/ncomms11493 · DOI · Paper page
  6. Ferray M, 1988, J. Phys. B: At. Mol. Opt. Phys., 21, L31, 10.1088/0953-4075/21/3/001 · DOI · Paper page

Cited by

Sorted by citations

Related

Authors
Young, L., Ueda, K., Gühr, M., Bucksbaum, P. H., Simon, M., Mukamel, S., Rohringer, N., Prince, K. C., Masciovecchio, C., Meyer, M., Rudenko, A., Rolles, D., Bostedt, C., Fuchs, M., Reis, D. A., Santra, R., Kapteyn, H., Murnane, M., Ibrahim, H., Légaré, F., Vrakking, M., Isinger, M., Kroon, D., Gisselbrecht, M., L’Huillier, A., Wörner, H. J., & Leone, S. R.
Affiliations
  • Argonne National Laboratory (US)
  • Tohoku University (JP)
  • University of Potsdam (DE)
  • SLAC National Accelerator Laboratory (US)
  • Centre National de la Recherche Scientifique (FR)
  • University of California, Irvine (US)
  • Universität Hamburg (DE)
  • Elettra-Sincrotrone Trieste S.C.p.A. (IT)
  • European X-Ray Free-Electron Laser (DE)
  • Kansas State University (US)
  • University of Nebraska–Lincoln (US)
  • Joint Institute for Laboratory Astrophysics (US)
  • Institut National de la Recherche Scientifique (CA)
  • Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy (DE)
  • Lund University (SE)
  • ETH Zurich (CH)
  • University of California, Berkeley (US)
Corresponding author
Young, Linda
ORCID
Venue
Journal of Physics B: Atomic, Molecular and Optical Physics
Publisher
IOP Publishing
Published
2018-01-09
Volume
51
Issue
3
Pages
032003
ISSN
  • 0953-4075 (ISSN-L)
  • 1361-6455
DOI
10.1088/1361-6455/aa9735
OpenAlex
W2784192443
Semantic Scholar
94ecaa3a47849546f2dd9cdcb89750b88eddad63
Cited by
337
References
226
Citations by year
2026: 17 · 2025: 32 · 2024: 40 · 2023: 48 · 2022: 47 · 2021: 53 · 2020: 54 · 2019: 30 · 2018: 16
FWCI
17.68
Type
journal article
Language
en
Open access
Licence
Locations
  • Journal of Physics B Atomic Molecular and Optical Physics (publishedVersion, cc-by)
  • K-State Research Exchange (Kansas State University) (submittedVersion, cc-by)
  • OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion, cc-by)
  • Repository for Publications and Research Data (ETH Zurich) (submittedVersion, cc-by)
  • Lincoln (University of Nebraska) (submittedVersion)
  • HAL (submittedVersion, other-oa)
  • DESY Publication Database (PUBDB) (Deutsches Elektronen-Synchrotron) (submittedVersion, other-oa)
  • eScholarship (California Digital Library) (submittedVersion)
  • publish.UP (University of Potsdam) (submittedVersion, cc-by)
  • Lund University Publications (Lund University) (submittedVersion)
  • Refubium (Universitätsbibliothek der Freien Universität Berlin) (submittedVersion, cc-by)
  • European XFEL (submittedVersion, cc-by)
  • Universitätsbibliothek der FU Berlin Hochschulschriftenstelle u. Dokumentenserver (cc-by)
  • ETH Zürich Research Collection (cc-by)
Funders
  • National Science Foundation (0310717, 1125844, 1663822, 1548924)
  • U.S. Department of Energy (FG02-04ER15571, DE‐FG02‐, 76SF00515, DE–AC02–76SF00515, DEFG0204ER15571, AC02‐76SF00515, DEFG0299ER14982, DESC0016494, DE-AC02-)
  • Gordon and Betty Moore Foundation (DE-AC02-76SF00515)
  • University of Chicago
  • Institut national de la recherche scientifique
  • Volkswagen Foundation
  • Ministry of Education, Culture, Sports, Science and Technology
  • Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
  • Eidgenössische Technische Hochschule Zürich
  • Knut och Alice Wallenbergs Stiftelse
  • Vetenskapsrådet
  • Centre National de la Recherche Scientifique
  • Universität Hamburg
  • Université Pierre et Marie Curie
  • Defense Advanced Research Projects Agency (1125844, W31P4Q, W31P4Q-13-1-0015)
  • Office of Science (AC02-76SF00515, DE-AC02-76SF0051 5, DE-AC02, DEFG0204ER15571, 76SF00515)
  • University of California, Irvine
  • Advanced Research Projects Agency
  • Deutsches Elektronen-Synchrotron
  • Division of Materials Research (DMR1548924, 1548924)
  • Division of Chemistry (CHE1663822)
  • Basic Energy Sciences (DE-AC02, DEFG02- 04ER15571, DE-FG02, 76SF00515, FG02-04ER15571, AC02-76SF00515, DE-AC-02-76SF00515)
  • Chemical Sciences, Geosciences, and Biosciences Division (DE-FG02-04ER15571, DE-AC02-76SF00515)
  • Air Force Office of Scientific Research
  • Army Research Office
  • Argonne National Laboratory
  • SLAC National Accelerator Laboratory
Topics
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Laser-Matter Interactions and Applications
  • Physical Sciences › Physics and Astronomy › Radiation › Advanced X-ray Imaging Techniques
  • Physical Sciences › Physics and Astronomy › Radiation › X-ray Spectroscopy and Fluorescence Analysis
Keywords
X-ray free-electron laser, high harmonic generation, coherent diffraction imaging, attosecond photoionization, conical intersections, ultrafast molecular dynamics

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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