Calculation of vibrational relaxation times in gaseous sulphur dioxide

Abstract

Approximate vibrational relaxation times have been calculated for gaseous sulphur dioxide at 373°K using the collision theory of Schwartz & Herzfeld (1954). Two major effective relaxation times are found; the shorter associated with the relaxation of the specific heat contribution of the lowest mode and the longer with the relaxation of the total contributions of the two higher modes. The results are compared with the recent ultrasonic dispersion data of Lambert & Salter (1957), a measure of agreement being found. The mechanism of vibrational excitation in gaseous sulphur dioxide is discussed and compared with that in some similar molecules. Tentative predictions are made about the relaxation behaviour of a few selected molecules.