Theoretical study of asymmetric molecular-frame photoelectron angular distributions forC 1sphotoejection fromCO2

Abstract

We report the results of ab initio calculations of cross sections and molecular-frame photoelectron angular distributions for $\text{C}\text{ }1s$ ionization of ${\text{CO}}_{2}$ and propose a mechanism for the recently observed asymmetry of those angular distributions with respect to the ${\text{CO}}^{+}$ and ${\text{O}}^{+}$ ions produced by subsequent Auger decay. The fixed-nuclei, photoionization amplitudes were constructed using variationally obtained electron-molecular ion scattering wave functions. We have also carried out electronic structure calculations which identify a dissociative state of the ${\text{CO}}_{2}^{2+}$ dication that is likely populated following Auger decay and which leads to ${\text{O}}^{+}+{\text{CO}}^{+}$ fragment ions. We show that a proper accounting of vibrational motion in the computation of the photoelectron angular distributions, along with reasonable assumptions about the nuclear dissociation dynamics, gives results in good agreement with recent experimental observations. We also demonstrate that destructive interference between different partial waves accounts for sudden changes with photon energy in the observed angular distributions.