Transmission properties of spark preionization radiation in rare-gas halide laser gas mixes

A charge collection apparatus was used to measure photocharge yields and transmission properties of light emitted from a spark preionizer discharge through various rare-gas halide laser gas mixes as well as through their component gas mixes. The data indicates that for HCl partial pressure (p) and photon path length (d) pd products /spl ges/100 Torr-cm, a narrow transmission window (114-124 nm) for preionization of XeCl and KrCl lasers occurs. In contrast, fluorine based rare-gas halide laser gas mixes were largely transparent over a critical 100-150 nm spectral window responsible for preionization. The role of gaseous impurities, two photon ionization processes, the photoelectric effect, passivation and air contamination on the photocharge signal and light transmission are described.