Surface Reaction of Methyl Mercaptan (CH3SH) with Hydrogen Atoms on Amorphous Solid Water

Abstract

Methyl mercaptan (CH _3 SH) is one of the S-bearing organic compounds found in the interstellar medium (ISM). In this study, we investigated the surface reactions of solid CH _3 SH with H atoms on amorphous solid water using experimental and computational methods to examine their physicochemical behavior in the ISM. Consequently, the primary product was discovered to be CH _4 . As the computational studies show that the dominant reaction pathway is H + CH _3 SH → CH _3 + H _2 S, the observed CH _4 would result from H addition to CH _3 . As relatively minor routes, the H abstraction processes from the –CH _3 and –SH functional groups of CH _3 SH, giving rise to CH _2 SH and CH _3 S radicals, are confirmed. Although these radicals may form CH _3 SH again by reactions with H atoms, the loss of CH _3 SH from the ice surface by chemical desorption would be minor.

Keywords

• Astrochemistry
• Pre-biotic astrochemistry