METAL EMISSIONS MONITORING USING EXCIMER-LASER FRAGMENTATION FLUORESCENCE SPECTROSCOPY

Photofragmentation of molecules using an excimer laser with subsequent detection of fluorescence from metal atoms formed in excited states i s a viable detection strategy for many metal species. Excimer laser fr agmentation-fluorescence spectroscopy (ELFFS) can provide continuous, real-time monitoring information for metals which evolve from a variet y of high-temperature processes, including combustion. Here we apply E LFFS to lead, manganese, nickel and chromium species in the postflame gases of a laboratory burner. Using a 193-nm argon fluoride laser we o btain quantitative relationships between signal strength and concentra tion in hot combustion products for metals injected into a flame; repr esentative spectra are shown. The effects of quenching environment and laser power on the signal are discussed. The ELFFS technique is sensi tive, providing ppb detection limits for these metals in a one-second measurement time.