Abstract
Vibrationally excited CS is produced directly by the photochemical decomposition of CS$_2$. The presence of S(3$^3$P) and the absence of S(3$^1$D) during the flash photolysis was demonstrated by vacuum ultra-violet spectroscopy. It is suggested that collision with atomic sulphur causes a fast vibrational relaxation of CS, probably involving multiple quantum transitions. The atomic sulphur decays by polymerization and not by reaction with CS$_2$.