WAVELENGTH-RESOLVED AND TIME-RESOLVED INVESTIGATION OF LASER-INDUCED PLASMAS AS A CONTINUUM SOURCE

Time- and wavelength-resolved laser-induced plasma emission spectra in helium, argon, nitrogen, air, and helium/argon mixture were obtained from 200 to 700 nm. Stability studies showed that plasmas formed in he lium had about 5% relative standard deviation in emission at most wave length regions. A radiant intensity of 8 x 10(11) photons/pulse.sr was produced at 633 nm with a moderate laser power. Plasma temporal devel opment was investigated in various gases. In general, the continuum em ission was observed only during the first few microseconds following t he laser onset. Plasmas in argon have the longest decay time, followed by helium and nitrogen. The feasibility of using the laser-induced pl asma as a continuum source for the study of transient molecular absorp tion was demonstrated.