ELECTRONIC EXCITATION OF H2 IN SLOW COLLISIONS WITH MOLECULAR-IONS

Excitation of molecular hydrogen has been studied in 1.8-keV collision s with molecular projectile ions H-2+, N2+, CO+, O2+, and CO2+ by mean s of energy-loss spectrometry using a high-resolution ion translationa l energy spectrometer. Excitation of the target H-2 is observed only i n the case of collisions with H-2+. Oscillator strengths for electroni c transitions to various electronic states are determined by simulatin g the measured energy-loss spectra with calculations using calculated Franck-Condon overlap integrals. Excitation of the projectile ions is observed in the case of collisions with N2+ and CO+ projectiles. Neith er projectile excitation nor target excitation is observed when experi ments are carried out with O2+ and CO2+ projectiles. The results obtai ned in the present study are interpreted as a manifestation of wave-fu nction-overlap effects involving the highest occupied molecular orbita ls of the target and projectile ions.