A Theoretical Investigation of the Low Lying Electronic States of CO2+ in Both Linear and Bent Configurations

Abstract

Using CASSCF and contracted CI ab initio methods the X̃ 2Πg, à 2Πu, B̃ 2Σ+u, C̃ 2Σg+ and ã 4Πu electronic states have been studied in both linear and bent geometries. A comparison with previous theoretical calculations and with available experimental data is presented. All four doublet states were found to be linear in their equilibrium configuration. Interest was focused on the crossing of the ã 4Πu and à 2Πu states, because of perturbations observed in lifetime measurements on certain rotational levels of the à 2Πu state. In order to provide an explanation for the longer lifetimes measured for excitations of the bending mode in the à 2Πu state, calculations of the electronic dipole transition moment for the Ã-X̃ transition have been obtained for certain nuclear configurations. Also, a discussion is presented on the interpretation of the photoelectron spectrum of the vibrational structure observed in the C̃ 2Σ+g state.