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 helium had about 5% relative standard deviation in emission at most wavelength regions. A radiant intensity of 8 x 10(11) photons/pulse.sr was produced at 633 nm with a moderate laser power. Plasma temporal development was investigated in various gases. In general, the continuum emission was observed only during the first few microseconds following the laser onset. Plasmas in argon have the longest decay time, followed by helium and nitrogen. The feasibility of using the laser-induced plasma as a continuum source for the study of transient molecular absorption was demonstrated.