Photodissociation and radiative processes in interstellar C₂

Abstract

Ab initio methods are used to compute photodissociation and radiative processes occurring in interstellar C2 from the X 1 Sigma g+ ground state. To this end, self-consistent-field+configuration interaction wavefunctions and potential energy curves of the X 1 Sigma g+ and the first four 1 Pi u states and transition moments between the ground and excited electronic states are computed. Photodissociation cross sections for absorption into the second and third 1 Pi u states are calculated and the corresponding interstellar photodissociation probability is found to be 0.73*10-10 s-1. Ground-state transition probabilities and absorption oscillator strengths f00 of the Phillips (A 1 Pi u-X 1 Sigma g+) and 2 1 Pi u-X 1 Sigma g+ systems are determined.