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.