Issue 37, 2022

Fragmentation of interstellar methanol by collisions with He˙+: an experimental and computational study

Abstract

Methanol is a key species in astrochemistry as its presence and reactivity provides a primary route to the synthesis of more complex interstellar organic molecules (iCOMs) that may eventually be incorporated in newly formed planetary systems. In the interstellar medium, methanol is formed by hydrogenation of CO ices on grains, and its fate upon collisions with interstellar ions should be accounted for to correctly model iCOM abundances in objects at various stages of stellar evolution. The absolute cross sections (CSs) and branching ratios (BRs) for the collisions of He˙+ ions with CH3OH are measured, as a function of the collision energy, using a Guided Ion Beam Mass Spectrometer (GIB-MS). Insights into the dissociative electron (charge) exchange mechanism have been obtained by computing the entrance and exit multidimensional Potential Energy Surfaces (PESs) and by modelling the non-adiabatic transitions using an improved Landau–Zener–Stückelberg approach. Notably, the dynamical treatment reproducing the experimental findings includes a strong orientation effect of the system formed by the small He˙+ ion and the highly polar CH3OH molecule, in the electric field gradient associated to the strongly anisotropic intermolecular interaction. This is a stereodynamical effect that plays a fundamental role in collision events occurring under a variety of conditions, with kinetic energy confined within intervals ranging from the sub-thermal to the hyper-thermal regime.

Graphical abstract: Fragmentation of interstellar methanol by collisions with He˙+: an experimental and computational study

Supplementary files

Article information

Article type
Paper
Submitted
30 may. 2022
Accepted
06 sep. 2022
First published
08 sep. 2022

Phys. Chem. Chem. Phys., 2022,24, 22437-22452

Fragmentation of interstellar methanol by collisions with He˙+: an experimental and computational study

V. Richardson, E. Valença Ferreira de Aragão, X. He, F. Pirani, L. Mancini, N. Faginas-Lago, M. Rosi, L. M. Martini and D. Ascenzi, Phys. Chem. Chem. Phys., 2022, 24, 22437 DOI: 10.1039/D2CP02458F

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