QUENCHING OF THE 750.4 NM ARGON ACTINOMETRY LINE BY H-2 AND SEVERAL HYDROCARBON MOLECULES

The quenching rate of the 750.4 nm actinometer line in argon by H-2 an d several hydrocarbons (CH4, C2H2, C2H4, C2H6) has been determined. Ar gon 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 fluorescenc e emission at 750.4 nm is measured. The quenching rates are inferred f rom the change of the decay time with the pressure of the quenching ga s. For hydrocarbons, the quenching rates are of the order of 10(-9) cm (3) s(-1). The radiative lifetime of the 4p'[1/2](0) is found to be 24 ns. (C) 1997 American Institute of Physics. [S0003-6951(97)03552-3].