Excitation of vacuum UV transitions of alkali-metal atoms by charge-exchange reactions

We investigate the vacuum UV radiation spectra of atoms and ions of Rb, Cs, He, Ne, and Ar in a discharge plasma of their mixtures at different concentration of metal vapors in rare gases. The reactions leading to population and deactivation of resonant states of rare-gas atoms were studied. The observation of lines 109.1, 119.6, and 124.7 nm, corresponding to the radiation transitions from the 5p ⁵5d6s ⁴ P _5/2 quasi-metastable autoionizing level of cesium, allowed us to estimate experimentally the cross section σ=(9±3) · 10^?15 cm² of the charge-exchange reaction of the metastable cesium ion on the cesium atom, giving as a result the above-mentioned quasi-metastable state of cesium.