Rate measurements of reactions of helium metastable species at atmospheric pressures. I. He (2 3S) in pure afterglows

Using resonance absorption spectrometry the rates of the reactions He(2 3S)+He(2 3S) Kaa→products and He(2 3S) +2HeKc→products have been measured in the afterglow period of electron beam excited discharges in helium at atmospheric pressures. Lorentz broadened absorber linewidths calculated using a simple classical interruption theory allowed absolute metastable concentrations to be determined. Reported rates for these reactions are in excellent agreement with literature values measured at lower pressures.