Vibrational relaxation of carbon monosulphide

Abstract

The relaxation of vibrationally excited CS, formed in the flash-initiated reaction: O(³P)+CS₂→ SO + CS, has been studied by monitoring the absorption of the A¹Π—X¹Σ⁺(2,1) band photoelectrically. Rates of decay were measured in the presence of various added gases, and hence rate constants determined for the de-excitation of CS(ν= 1) by ortho-H₂, para-H₂, HD, ³He, D₂, ⁴He, N₂O, CO₂, H₂O, D₂O, H₂S and D₂S. The much greater efficiency of N₂O compared to CO₂ shows clearly how the probability of vibration-vibration energy exchange is enhanced if both species are infra-red active. Vibration-rotation energy transfer may occur with the collision partners which have small moments of inertia. Where appropriate, experimental transition probabilities are compared to those predicted by Sharma's recently published theory.