Study of reactive and inelastic collisions by time resolved gain spectroscopy. I. Chemical vibrational excitation and vibrational relaxation of HCl occurring with the reaction of hydrogen with chlorine

Abstract

A method, which may be termed ’’time-resolved gain spectroscopy’’ is applied to the study of the reaction of hydrogen with chlorine. This method is a direct way to know at any time (with a precision of 1 μsec) the population of HCl molecules on the ground level or an excited level. At the early beginning of the reaction, the formation rate of molecules in various excited vibrational energy levels can be determined directly. The relative rate constants kv for the reaction to form HCl molecules on vibrational levels v=0–4 have been obtained. When the chemical reaction stops, some relaxation processes go along and may be studied: The rate constants were derived for the de-excitation of HCl from vibrational levels v=1–4 by V–T transfers occurring upon collisions with hydrogen molecules. The concurrent processes of reaction and deactivation, in the intermediate stage, were analyzed and a computer simulation of the complete kinetics was developed.