IN-SITU DIAGNOSTICS OF CHEMICALLY REACTING FLOWS USING LASER-INDUCED BREAKDOWN SPECTROSCOPY

摘要

Laser-induced breakdown spectroscopy (LIBS hereafter) hasrnemerged as a powerful diagnostic method in many application areas. LIBS operates by a focusedrnlaser beam inducing multiple ionization and dissociation of the target molecules. The high energyrnstate at the focal point of the laser beam produces dissociated, excited elements which radiaterncharacteristic emission bands while returning to ground states. These emission wavelengths andrnintensities can be used to infer the elemental composition of the sample. In air at atmosphericrnpressure, laser energy density of 109 W/cm2 is typically required to produce laser-inducedrnbreakdown, clearly visible as “sparks” (Fig. 1). There have been numerous fundamental andrnapplication studies of LIBS (see as examples Refs. 1-13, 23-26), particularly in recent years duernto the increased interest in developing diagnostic methods for complex, toxic chemicals underrnarbitrary conditions.