Quenching of the 750.4 nm argon actinometry line by H2 and several hydrocarbon molecules

Abstract
The quenching rate of the 750.4 nm actinometer line in argon by H2 and several hydrocarbons (CH4, C2H2, C2H4, C2H6) has been determined. Argon atoms at room temperature are excited by two-photon excitation at 184 nm to the 4p′[1/2]0 state, and the decay time of the fluorescence emission at 750.4 nm is measured. The quenching rates are inferred from the change of the decay time with the pressure of the quenching gas. For hydrocarbons, the quenching rates are of the order of 10−9 cm3 s−1. The radiative lifetime of the 4p′[1/2]0 is found to be 24 ns.