Abstract
The advent of synchrotron radiation sources and the subsequent improved experimental studies on molecular photoionization processes has stimulated the development of theoretical methods for studying electron-molecule scattering. With improved monochromator resolution it is now possible to study the Auger spectra of diatomic molecules such as carbon monoxide (CO) in great detail. Our current study of CO, focuses on the computation of photoionization cross sections for the auger decay of CO after the Cls->2n* excitation. This calculation is performed in two stages; the first stage involves the use of a commercially prepared suite of programs, GAMESS, to calculate a set of natural orbital using the CO corehole configuration. The orbitals are obtained by performing a single-reference singles and doubles configuration-interaction calculation (CI). The second step employs the multichannel Schwinger approach to perform a second Cl, which is then used in the final calculation of the ionization cross sections. The calculation of the cross sections is performed at two levels of approximation, the first employs a fixed-nuclei approximation and the second involves the examination of the cross section as a function of varying internuclear distance, thus allowing for the effects of molecular vibration. Analysis of these cross section peaks provide a wealth of information about the corehole potential, such as the branching ratios for numerous possible channels, the core hole lifetime, oscillator strength, a theoretical ion yield spectrum for the C I s->27c* excitation and the electronic deexcitation spectrum, with excellent correlation to experiment.
Botting, Shaleen Kaye (1997). Auger resonance study for the C1s 2pi* excitation of CO. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -B68.