Insights into rotational (de-)excitation of protonated tricarbon monoxide (HC3O+) by collision with helium atoms at low temperature

Abstract

ABSTRACT New 2D potential energy surface (2D-PES) of interaction between protonated tricarbon monoxide (HC3O+) in its electronic ground state (X1Σ+) and helium (He) atoms is generated. The ab initio 2D-PES is computed by adopting explicitly correlated coupled cluster approach with single, double, and perturbative triple excitation (CCSD(T)-F12a) connected to augmented-correlation consistent-polarized valence triple zeta (aVTZ) Gaussian basis set. A global minimum at (θ = 80°, R = 5.6 bohr) with a well depth of 135.67 cm−1 and a local minimum at (θ = 180°, R = 9.95 bohr) with a well depth of 113.39 cm−1 are obtained. Rotational cross-sections of propynol cation HC3O+ induced by collision with He atoms are performed involving the 11 first rotational levels for total energy up till 150 cm−1, to be under the first vibrational mode, via coupled states (CS) approach. Thermal rate coefficients are then calculated for temperature until 25 K. No clear propensity rules are obtained where |ΔJ| = 1 processes predominate.