Dissociative excitation of TlI and TlCl by rare-gas metastable atoms and N2 A 3Σ+u

Abstract

The reactions of TlCl and TlI with rare gas He(3S), Ar(3P2), Kr(3P2), Xe(3P2), and N2(A 3Σ+u) metastable species were studied in a flowing afterglow apparatus. In all cases, emission from the excited states of Tl was observed, and with helium we also observed the 190.8 nm line issued from the 3P1 level of Tl+. We have verified that these excited levels are populated following a first-order process. The rate constants for the different exit channels of dissociative excitation have been determined and the influence of radiative cascade effects is discussed. The largest rate constants, on the order of 10−10 cm3 mol−1 s−1, were obtained for the reactions of TlCl and TlI with xenon, and TlCl with krypton, for which an ionic exit channel is not possible because of energy conservation criteria. The rate constants for the reactions with argon are much smaller, about 10−13 cm3 mol−1 s−1. A large rate constant, 1.3×10−9 cm3 mol−1 s−1 was obtained for the excitation of Tl+(3P1) level by helium metastable atoms.