Energy transfer between helium metastable particles and neon

Light absorption and emission spectroscopy was used to study the time dependences of the ${\mathrm{He}}^m\left(2\mathrm{}{}_{}{}^3{}_{}{}^{}S\right)$, ${\mathrm{He}}_2^m\left(a{}_{}{}^3{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}\right)$, and ${\mathrm{Ne}}^m\left({}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}\right)$ 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 ${\mathrm{He}}^m\left(2\mathrm{}{}_{}{}^3{}_{}{}^{}S\right)$ and Ne with a reaction rate constant of 4.3×${10}^{-12\mathrm{}}$ ${\mathrm{cm}}^3$ ${\mathrm{s}}^{-1\mathrm{}}$, in agreement with previous studies. The $\mathrm{Ne}\left(2\mathrm{}{p}^{5}3s\right)$ states are formed directly by the dissociative-excitation-transfer mechanism ${\mathrm{He}}_2^m\left(a{}_{}{}^3{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}\right)+\mathrm{Ne}\to {\left({\mathrm{He}}_2\mathrm{Ne}\right)}_r^{*}\to \mathrm{Ne}\left(2\mathrm{}{p}^{5}3s\right)+2\mathrm{He}$ 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.