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 is a viable detection strategy for many metal species. Excimer laser fragmentation-fluorescence spectroscopy (ELFFS) can provide continuous, real-time monitoring information for metals which evolve from a variety of high-temperature processes, including combustion. Here we apply ELFFS to lead, manganese, nickel and chromium species in the postflame gases of a laboratory burner. Using a 193-nm argon fluoride laser we obtain quantitative relationships between signal strength and concentration in hot combustion products for metals injected into a flame; representative spectra are shown. The effects of quenching environment and laser power on the signal are discussed. The ELFFS technique is sensitive, providing ppb detection limits for these metals in a one-second measurement time.