De-excitation Rate Constants for Helium Metastable Atoms with Several Atoms and Molecules

Abstract

The de‐excitation rate constants for $\mathrm{He}{\text{(2}}^1\mathrm{S)}\mathrm{and\; He}{\text{(2}}^3\mathrm{S)}$ metastables have been measured with the following gases: Ne, Ar, Kr, Xe, H₂, D₂, N₂, CO, NO, O₂, CO₂, NO₂, NH₃, SF₆, CH₄, C₂H₆, C₃H₈, and C₄H₁₀. These rate constants were measured in a flowing afterglow system using the neon 5689.8 and 7032.4‐Å emission lines as detectors for the $\mathrm{He}{\text{(2}}^1\mathrm{S)}\mathrm{and\; He}{\text{(2}}^3\mathrm{S)}$ , respectively. In all of the above cases the He${\text{(2}}^1\mathrm{S)}$ rate constants were several times faster than those of the He${\text{(2}}^3\mathrm{S)}$ .