Pressure dependence of the reaction of He2(3Σ) metastable molecules with Ar

Abstract

This paper reports the re‐examination and analysis of data characterizing the excitation transfer reaction of metastable He₂(³Σ_u) helium molecules with argon atoms. Data were originally obtained from measurements of the transient optical absorption of the 4650 Å, ³Σ_u→³π_g helium transition in high pressure, e‐beam afterglows, and in low pressure, electric discharges. Rate coefficients have been obtained from the data and resolved into components describing the bimolecular and termolecular reactions of He₂(³Σ_u) with Ar. Values of 1.5×10⁻¹⁰ cm³ sec⁻¹ and 2.4±0.8×10⁻³⁰ cm⁶ sec⁻¹, respectively, were found. The former corresponds to a reaction probability of 0.18 and the latter represents the first measurements of a termolecular excitation transfer reaction of He₂(³Σ_u).