LASER-INDUCED PHOTOIONIZATION IN THE DARK SPACE OF A HOLLOW-CATHODE

We describe an experimental set-up to measure fast current pulses gene rated via laser-induced photoionization in the dark space of a high-cu rrent hollow cathode. With suitably matched delay lines reflections di sturbing the signals are avoided without debasing the response functio n of the system. An advanced theoretical model allows the determinatio n of absolute photoionization cross sections and number densities expl oiting the time-resolved shape of the current pulses. Experiment and t heory have been tested on the autoionizing CuI 4p F-4(7/2)0-5s D-4(5/2 ) at 458.824 nm. We measured a cross section for this transition with sigma = 15 Mb and a density of the lower level of N-0 = 2 x 10(11) cm( -3).