Electronic energy transfer from metastable argon (4s 3 P 2,0) to xenon, oxygen and chlorine atoms

Abstract

The rate constants for product channels arising from quenching of metastable argon (³P_{2, 0}) atoms by xenon, oxygen and chlorine atoms have been measured by observing product emission intensities in a discharge–flow apparatus. The xenon and chlorine atom cases provide interesting contrasts in the distribution of product states, although the total quenching rate constants are large and of similar magnitude. Quenching by xenon gives a broad distribution of exit Xe* channels, but all are relatively close ( 0.25 eV) to the entrance channel in energy. Quenching by Cl atoms also gives a variety of products but the favoured channels are the Cl*(4s) states which are 2.5 eV below the entrance channel. The difference in exit channel distributions reflects the presence of attractive potentials for ArCl*, including the Ar⁺Cl^– potential. Quenching by oxygen atoms provides a third contrast because the quenching is specific with one exit channel, O(3p²P), being favoured. Since this channel is 0.5 eV below the entrance channel, attractive potentials again must be important.