SiS formation via gas phase reactions between atomic silicon and sulphur-bearing species

Abstract

ABSTRACT The potential energy surface for the Si + SH and Si + SH2 reactions is explored using the highly accurate explicit correlation multireference configuration interaction method. For atomic silicon colliding with SH, SiS + H is predicted to be the main reaction channel with no activation energy. The reaction Si + SH2 → SiS + H2 is found to be largely thermodynamically favourable, but likely to be slow, due to its spin forbidden nature. Several details on possible mechanisms are evaluated, and implications for astrochemical models are discussed. Among other results, we show that SiS is stable towards collisions with H and H2, and that the HSiS molecule will quickly be converted to SiS in collisons with atomic hydrogen.