Rovibrational quenching of C$_2$-anions in collisions with He, Ne, and Ar atoms

TL;DR

This study calculates rovibrational collision rates of C$_2$-anions with noble gases, finding Ar induces higher vibrational quenching rates, which impacts laser cooling strategies.

Contribution

It provides detailed quantum scattering calculations of rovibrational inelastic collisions of C$_2$-anions with He, Ne, and Ar, highlighting the effectiveness of Ar for vibrational quenching.

Findings

Vibrational quenching rates with He and Ne are very small.

Ar causes significantly higher vibrational quenching rates.

Results inform optimal buffer gases for laser cooling of C$_2$-anions.

Abstract

The dicarbon molecular anion is currently of interest as a candidate for laser cooling due to its electronic structure and favorable branching ratios to the ground electronic and vibrational states. Helium has been proposed as a buffer gas to cool the molecule's internal motion. We calculate the cross sections and corresponding rates for rovibrational inelastic collisions of the dicarbon anion with He, and also with Ne and Ar, on three-dimensional ab initio potential energy surfaces using quantum scattering theory. The rates for vibrational quenching with He and Ne are very small and are similar to those for small neutral molecules in collision with helium. The quenching rates for Ar, however, are far larger than those with the other noble gases, suggesting that this may be a more suitable gas for driving vibrational quenching in traps. The implications of these results for laser cooling of the dicarbon anion are discussed.