Laser and microwave induced breakdown spectroscopy: basis for a new detection technique for chemical and biological agents

Summary form only given. Laser induced breakdown in air and solutions is a well-investigated phenomena. The emission spectra reveal the presence of atomic ionic spectra of gases from air and volatilized metallic and other ions. Microwave induced breakdown in solution is a recently observed phenomenon (Kiel et al., IEEE Transactions in Plasma Science 28: 161-167, 2000). To accomplish the latter efficiently, soluble organic semi-conductor (diazoluminomelanin) needs to be added to solutions exposed to high power microwave pulses (1.25 GHz, 10 Hz pulse rate, 6 ms pulses, 2 MW peak power). When comparable solutions are exposed to laser pulses (1 ns pulse, 540 nm wavelength), the emissions reveal not only the expected atomic spectra, but also spectra associated with the organic semi-conductor. The microwave induced breakdown spectra show similar highly resolvable emission peaks. Spectra with common and unique features were observed for the bacteria E. coli, anthrax spores, and chemical derivatives of the organic semi-conductor. Included in these spectral bands were peaks representative of buffer and other solution components such as sodium and chlorine. Therefore, the separate or combined use of cavitation generated by pulsed laser and/or pulsed high power microwave sources can generate analytical chemical and biological spectra for identification of these agents.