Rotational state-changing collisions of C2H- and C2N- anions with He under interstellar and cold ion trap conditions: A computational comparison

Jan Franz; Barry P Mant; Lola González-Sánchez; Roland Wester; Franco A Gianturco

doi:10.1063/5.0011585

Rotational state-changing collisions of C₂H^- and C₂N^- anions with He under interstellar and cold ion trap conditions: A computational comparison

J Chem Phys. 2020 Jun 21;152(23):234303. doi: 10.1063/5.0011585.

Authors

Jan Franz¹, Barry P Mant², Lola González-Sánchez³, Roland Wester², Franco A Gianturco²

Affiliations

¹ Department of Theoretical Physics and Quantum Informatics, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, ul. Narutowicza 11/12, 80-233 Gdańsk, Poland.
² Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstr. 25/3, 6020 Innsbruck, Austria.
³ Departamento de Química Física, University of Salamanca, Plaza de los Caídos s/n, 37008 Salamanca, Spain.

PMID: 32571047
DOI: 10.1063/5.0011585

Abstract

We present an extensive range of quantum calculations for the state-changing rotational dynamics involving two simple molecular anions that are expected to play some role in the evolutionary analysis of chemical networks in the interstellar environments, C₂H^- (X¹Σ⁺) and C₂N^- (X³Σ^-), but for which inelastic rates are only known for C₂H^-. The same systems are also of direct interest in modeling selective photo-detachment experiments in cold ion traps where the He atoms function as the chief buffer gas at the low trap temperatures. This study employs accurate, ab initio calculations of the interaction potential energy surfaces for these anions, treated as rigid rotors, and the He atom to obtain a wide range of state-changing quantum cross sections and rates at temperatures up to about 100 K. The results are analyzed and compared for the two systems to show differences and similarities between their rates of state-changing dynamics.