Momentum Distributions ofNen+Ions Created by an Intense Ultrashort Laser Pulse

Abstract

Vector momentum distributions of ${\mathrm{Ne}}^{n+}$ $(n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1,2,3)$ ions created by 30 fs, $\mathrm{\ensuremath{\approx}}1\mathrm{PW}/{\mathrm{cm}}^{2}$ laser pulses at 795 nm have been measured using recoil-ion momentum spectroscopy. Distinct maxima along the light polarization axis are observed at 4.0 and 7.5 a.u. for ${\mathrm{Ne}}^{2+}$ and ${\mathrm{Ne}}^{3+}$ production, respectively. Hence, mechanisms based on an instantaneous release of two (or more) electrons can be ruled out as a dominant contribution to nonsequential strong-field multiple ionization. The positions of the maxima are in accord with kinematical constraints set by the classical ``rescattering model.''