Energy transfer between helium metastable particles and neon

Abstract

Light absorption and emission spectroscopy was used to study the time dependences of the ${\mathrm{He}}^{m}(2^{3}S)$, ${\mathrm{He}}_{2}^{m}(a^{3}\ensuremath{\Sigma}_{u}^{+})$, and ${\mathrm{Ne}}^{m}(^{3}P_{2})$ number densities and spectral-line emission intensities from 19 ${\mathrm{Ne}}_{\mathrm{I}}$ states during the afterglow of helium-neon discharges. The ${\mathrm{Ne}}_{\mathrm{I}}$ states below 20.56 eV are produced, either directly or by cascading, by excitation transfer between ${\mathrm{He}}^{m}(2^{3}S)$ and Ne with a reaction rate constant of 4.3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}12}$ ${\mathrm{cm}}^{3}$${\mathrm{s}}^{\ensuremath{-}1}$, in agreement with previous studies. The $\mathrm{Ne}(2{p}^{5}3s)$ states are formed directly by the dissociative-excitation-transfer mechanism ${\mathrm{He}}_{2}^{m}(a^{3}\ensuremath{\Sigma}_{u}^{+})+\mathrm{Ne}\ensuremath{\rightarrow}{({\mathrm{He}}_{2}\mathrm{Ne})}_{r}^{*}\ensuremath{\rightarrow}\mathrm{Ne}(2{p}^{5}3s)+2\mathrm{He}$ involving an intermediate repulsive state. No evidence was found for the production of ${\mathrm{Ne}}_{\mathrm{I}}$ energy levels above 20.56 eV by binary energy-transfer processes.