Photofragment fluorescence as an analytical technique: application to gas-phase alkali chlorides

Photodissociation of gas-phase compounds using a laser at suitably short ultraviolet wavelengths can produce electronically excited photofragments. Detection of fluorescence from these excited fragments, particularly atomic fragments, allows sensitive and quantitative density measurements, while signal strength as a function of dissociation laser wavelength allows differentiation among compounds that yield the same photofragment. Initial results on the determination of trace amounts of alkali chlorides demonstrate sub-parts-per-billion sensitivity.