Photoemission resulting from collisions of I2 with 5–100 eV electrons

Abstract

We have determined absolute apparent excitation cross sections for photoemission in the 300–1050 nm spectral region resulting from collisions of I2 with electrons of 4.8–100 eV translational energy. Experiments were done in single collision conditions and emission is observed from I2, I2 +, I and I+. All the emission features appear to turn on at the energy thresholds for formation of the respective excited state species. At higher electron beam energy the spectra are dominated by emissions from the strong I2 + A–X band, as well as the intense emission from several I 5s 25p 46s states. An attempt to determine the initial I2 + A populations generated from electron impact is discussed. These populations are determined from simulations of the I2 + A–X emission band using both experimentally and theoretically determined potential energy surfaces available in the literature. Direct, vertical formation of I2 + A from I2 X is only supported in the case of the ab initio potential energy surface.