Electronic excitation. Analogy between electronically excited state atoms and alkali metal atoms

Abstract

A comparison is made between the reactions of alkali metal atoms and highly electronically excited atoms. The np⁵n+ 1s(³P₂), and (³P₁) states of Ar, Kr and Xe are used as examples of excited states. The reactive quenching data of the rare gases with halogens and polyatomic halides are summarized and compared with similar data for the alkali metal atoms. The entrance channel properties are very similar for both classes of reagents. Also, the vibrational energy disposal to the products is similar in both cases. The main difference is that a relatively small fraction of the total quenching for most polyatomic reagents results in rare gas halide formation. A second difference is that the rare gas atom reactions yield two electronic state products rather than one as for alkali metal atom reactions. The low branching fraction for rare gas halide formation illustrates the extensive coupling between electronically excited state potentials at energies above 8 eV. Simulation of the XeX* bound–free spectra from the Xe(³P₂)+ Cl₂, Br₂ and I₂ reactions strongly suggests that 〈ƒ_v〉 declines in this series.