Possible scenarios for SiS formation in the interstellar medium: Electronic structure calculations of the potential energy surfaces for the reactions of the SiH radical with atomic sulphur and S₂

Marzio Rosi , Luca Mancini , Dimitrios Skouteris , Cecilia Ceccarelli (1) , Noelia Faginas Lago , Linda Podio , Claudio Codella , Bertrand Lefloch (1) , Nadia Balucani

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble

In this Letter we report on the first characterization of the reactions SiH + S and SiH + S₂ by means of electronic structure calculations of the stationary points along the reactive potential energy surfaces. According to our calculations, both reactions are barrierless and can lead to the formation of SiS (a species observed in interstellar objects) for which there are no convincing formation routes in current astrochemical models. Furthermore, we have verified that SiS₂ cannot be considered an interstellar reservoir of sulphur because it is easily attacked by the abundant H atoms.

Domaines: Planète et Univers [physics]

Marzio Rosi, Luca Mancini, Dimitrios Skouteris, Cecilia Ceccarelli, Noelia Faginas Lago, et al.. Possible scenarios for SiS formation in the interstellar medium: Electronic structure calculations of the potential energy surfaces for the reactions of the SiH radical with atomic sulphur and S₂. Chemical Physics Letters, 2018, 695, pp.87-93. ⟨10.1016/j.cplett.2018.01.053⟩. ⟨insu-03693572⟩