Theoretical atomic collision physics. Final report, July 1, 1987-- June 30, 1995

Abstract

This is the final report of research activities supported by the most recent grant to the theoretical atomic collision physics program at Rice University. For this most recent 3-year grant, the focus has been the study of excitation and charge-transfer in atom-atom and ion-atom collisions. Emphasis has been placed on low-velocity collision processes involving initially excited atoms, including ``low Rydberg`` atoms. Two particular objectives of this research were to examine the dependence of state-changing collision cross sections and other observables on the orientation and alignment of the initial excited orbitals and to look for ``intracollisional interference`` effects, speculated to arise from spatially separated interactions during a collision involving a highly excited atom. A number of radiative and non-radiative charge transfer studies involving ground-state atoms and ions were continued from the previous grant period. Several unanticipated personnel changes prevented execution of some of the proposed research, including the studies of collisions involving negative ions and electron-attaching atoms and the development of new theoretical techniques for handling the ``strong coupling`` regime. These remain challenging and fundamentally important research topics. Research highlights briefly described in the report deal with: spherical and non-spherical low-Rydberg atom collisions; alignment effects in collisions of Na(3p) with He{sup +} ions; near-resonant electron capture at very low energies; ion-atom and ion-molecule collisions, including electron capture; and low- energy processes involving collisions of H{sup +} with He, Na, and K atoms. The report also lists publications since 1991 reporting on the grant work.