CLUSTER FORMATION AND URANIUM PHOTOIONIZATION IN THE AFTERGLOW OF A PULSED HOLLOW-CATHODE LAMP

Uranium photoionization was observed in the afterglow of pulsed hollow cathode lamps illuminated by a dye laser tuned near the electronic tr ansition around 591.5 nm (L-5(6)0-16 900 cm(-1) M-7(7)). The photoioni zation signal was used to monitor the time evolution of the ground sta te uranium vapor density in the cathode hole, Lifetimes over 1 ms were measured for the uranium vapor; that makes this device attractive for multistep photoionization spectroscopy. The obtained results lead to the conclusion that these long times are due to cluster formation in t he afterglow. (C) 1998 American Institute of Physics. [S0034-6748(98)0 4302-0].