Understanding the destruction of CH+ with atomic hydrogen at low temperatures: a non-adiabatic dynamical study

Abstract

Carbon hydrides play a crucial role in the formation of complex organic molecules in highly UV illuminated regions of the interstellar medium (ISM). The formation of CH+ is the first step in the reactions leading to the formation of various carbon hydrides. CH+ formation is relatively well understood with strong agreement between theoretical and experimental results. However, its destruction by collision with the H atom, at low temperatures of interest in the ISM, is in contrast still not well understood and there is a large discrepancy between theoretical and experimental data [R. Plasil et al., AstroPhys. J., 2011, 737, 1], which are almost an order of magnitude smaller than various classical and quantum mechanical calculations. In this work we have computed and fitted a new set of non-adiabatic potential energy surfaces (PES) for the title system, including the three lower adiabatic states. We then investigate three possible sources of disagreement with the experimental results: non-adiabatic effects from regions near the conical intersections, and rotational and vibrational excitation of the CH+ molecule. We conclude that vibrational excitation of the CH+ plays a major role in reducing the reactivity at low temperatures, and we raise the question of whether vibrational thermalization of the CH+ is not fully achieved in the experiment. Such non-thermalized conditions could explain the decrease of the measured reaction rate constant.

Graphical abstract: Understanding the destruction of CH+ with atomic hydrogen at low temperatures: a non-adiabatic dynamical study

Supplementary files

Article information

Article type
Paper
Submitted
07 May 2025
Accepted
25 Jun 2025
First published
26 Jun 2025
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2025, Advance Article

Understanding the destruction of CH+ with atomic hydrogen at low temperatures: a non-adiabatic dynamical study

P. del Mazo-Sevillano, A. Aguado, F. Lique, R. A. Jara-Toro and O. Roncero, Phys. Chem. Chem. Phys., 2025, Advance Article , DOI: 10.1039/D5CP01718A

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