Spectroscopy with Polarized Light

Abstract

Polarized light is used in electronic spectroscopy not only to obtain information about the positions. Intensities, and fine structures of absorption and luminescence bands, which can be obtained by normal electronic spectroscopy of solutions, but also to determine the orientation of the transition moments in relation to the molecular framework. The theoretical and experimental principles of molecular optical anisotropy are briefly described, and the three most successful methods (spectroscopy after mechanical alignment of the molecules on films and in crystals, or after electrical alignment in solution, and luminescence polarization of solid solutions) are discussed in detail and illustrated by typical examples. In connection with luminescence polarization, special emphasis is placed on triplet‐singlet phosphorescence. Reference is made to the importantce of polarization measurements on liquid solutions in biochemistry (study of intermolecular interactions of macromolecules by measurement of the rotational relaxation times).