Abstract

The spectroscopic detection and identification of many molecules is hampered by the absence of absorption in readily accessible spectral regions (infrared to near ultraviolet) or, when absorption is present, by the absence of distinctive spectral features. For such molecules which have characteristic moieties, it is reasonable to consider the possibility of (1) fragmenting the species of interest by subjecting it to high intensity laser radiation and (2) taking advantage of the unique spectral signatures of the fragments to detect, and deduce the identity of, the parent. We are currently studying the utility of the ArF and KrF lasers as photolysis lasers in this technique. Laser-induced fluorescence is used as the fragment probing device. We find that focused excimer laser radiation is capable of generating photochemical activity via multiphoton absorption in molecules which have no absorption at the near-ultraviolet single-photon level. A good example of the application of this technique is the excimer laser fragmentation of organophosphonates. In addition to organic fragments, the PO radical is produced in quantities readily detectable by laser-induced fluorescence with a very distinctive spectral signature. Additional examples demonstrating the excimer laser production of spectrally distinctive photofragments are discussed.

© 1985 Optical Society of America