Experimental and computational studies of the hydrogenation of carbon disulfide (CS2) on ice analogues

Thanh Nguyen; Germán Molpeceres; Yasuhiro Oba; Marcelino Agúndez; Gisela Esplugues; José Cernicharo; Naoki Watanabe

paper

Experimental and computational studies of the hydrogenation of carbon disulfide (CS2) on ice analogues

arXiv:2602.21126

Abstract

Carbon disulfide (CS $_{2}$ ) is one of the sulfur-bearing species expected to be present in the interstellar medium (ISM). In this study, we investigated the surface reactions of solid CS $_{2}$ with hydrogen (H) atoms on amorphous solid water (ASW) using laboratory experiments supported by computational calculations. Our results show that CS $_{2}$ reacts with H atoms through quantum tunneling in the initial step, followed by successive H addition reactions, with or without activation barriers, on icy surfaces. These processes lead to the formation of several sulfur-bearing species, including hydrogen sulfide (H $_{2}$ S), methyl mercaptan (CH $_{3}$ SH), and small amounts of dithioformic acid (HC(S)SH) and methanedithiol (CH $_{2}$ (SH) $_{2}$ ). The observed reactivity of CS $_{2}$ with H atoms provides a plausible explanation for the non-detection of CS $_{2}$ in interstellar ices. Furthermore, the efficient hydrogenation of the complex molecules derived from CS $_{2}$ , namely HC(S)SH and CH $_{2}$ (SH) $_{2}$ , suggests that these species could be easily undergone with H atoms to produce other S-bearing species under ISM conditions.

Accepted in MNRAS