Generalized oscillator strengths. Technical progress report, six years, January 1, 1970--July 1, 1976. [Summaries of research activities at Carnegie-Mellon University

Abstract

Progress in the study of generalized oscillator strengths since January 1, 1970 is reviewed. The status of methods for the experimental determination of electron collision cross sections and generalized oscillator strengths is discussed including the comparison of inelastic and elastic scattering when elastic cross sections are available, the use of a comparison gas with a transition of known cross section, and the determination of optical oscillator strengths from forward scattering spectra. Outstanding discrepancies between limiting generalized oscillator strengths (at zero momentum change) and optical oscillator strengths are resolved for the most part. There are no longer any outstanding discrepancies involving refractive indices. Two new selection rules, one relating to singlet-singlet transitions, the other to singlet-triplet transitions are described. Other deviations from the Born approximation at large momentum changes are discussed. Generalized oscillator strengths are applied to the calculation of cross sections (in Born approximation) for resonant energy transfer in collision between two molecules one of which is excited. A list of publications is included.