Volume 25: Optical Methods of Investigating Solid Bodies, 1965 The Lebedev Physics Institute Series, Vol. 25

The principal results of the work are as follows: 1. A simplified technique was devised for obtaining Raman spectra of powders. 2. The Raman and infrared absorption spectra of the following oxides were investigated: AsP3' SbP3' As 0 • SbP5. Te02. Ge02 (two forms) in the crystalline state, and ASP3' Ge02' Te0 in the glassy state. 2 5 2 3. The vibrational spectra of the crystalline and glassy forms of the oxides ASP3' Ge02' Te02 are simi­ lar in many main respects, indicating a similarity of their structural units which determine the vibrational spec­ tra of these substances. 4. By a study of the vibrational spectrum it was shown that arsenious anhydride has a molecular structure and consists of As0 molecules having symmetry of the point group Td' The force constants and vibration fre­ 4 6 quencies of the As 0 molecule were calculated. and the vibrational spectrum of arsenious anhydride was re­ 4 6 liably interpreted with the aid of these results. 5. A similar result was obtained for antimonous anhydride. consisting of Sb0 molecule.s with symmetry 4 6 ofthe point group Td. The force constants for this molecule were found and the vibrational spectrum was calculated.

I. Polyatomic Molecules and Molecular Crystals (aims, methods, and objects of the investigation, statement of problems, review of literature).- II. Anisotropy of Molecules (determination of the orientation of radiating oscillators with respect to the axes of the molecules by means of the polarization spectra of the luminescence of solutions).- III. The Oriented Gas Model and its Application to Molecular Crystals (polarization diagrams of luminescence).- IV. Migration of Excitation Energy Between the Molecules in Molecular Crystals (dependence of the polarization of the luminescence on that of the exciting light).- V. The Part of Free Excitons in the Luminescence of Molecular Crystals (study of the relation between the degree of polarization and the wavelength of the luminescence).- VI. Polarization of Radioluminescence in Molecular Crystals and Effect of Ionizing Radiations on the Polarization of Their Photoluminescence.- VII. Experimental Methods.- I. Experimental.- II. Vibrational Spectra of Oxides with Molecular Lattice Structure.- III. Vibrational Spectra of Glass-Forming Oxides with Coordination Lattice Structure.- IV. Vibrational Spectra of Substances with Chain Lattice Structure.- Calculation of Cross Sections for Excitation of Atoms and Ions by Electron Impact.