Photodissociation of CS from Excited Rovibrational Levels

TL;DR

This study computes accurate photodissociation cross sections for CS molecules from various rovibrational levels, using advanced ab initio methods, and discusses implications for astrophysical environments and radiation fields.

Contribution

It provides new ab initio potential curves and transition dipole moments, and comprehensive cross sections for CS photodissociation across a wide temperature range.

Findings

Photodissociation from highly excited states is negligible.

Cross sections vary significantly with temperature and radiation field.

Results are applicable to modeling astrophysical environments.

Abstract

Accurate photodissociation cross sections have been computed for transitions from the X $^1\Sigma^+$ ground electronic state of CS to six low-lying excited electronic states. New ab initio potential curves and transition dipole moment functions have been obtained for these computations using the multi-reference configuration interaction approach with the Davidson correction (MRCI+Q) and aug-cc-pV6Z basis sets. State-resolved cross sections have been computed for transitions from nearly the full range of rovibrational levels of the X $^1\Sigma^+$ state and for photon wavelengths ranging from 500 $\text{\AA}$ to threshold. Destruction of CS via predissociation in highly excited electronic states originating from the rovibrational ground state is found to be unimportant. Photodissociation cross sections are presented for temperatures in the range between 1000 and 10,000 K, where a Boltzmann distribution of initial rovibrational levels is assumed. Applications of the current computations to various astrophysical environments are briefly discussed focusing on photodissociation rates due to the standard interstellar and blackbody radiation fields.