WBS Edge-Effect Dissassociation Detected by LIF

The problem of detecting hazardous trace species rapidly and sensitively is a difficult spectroscopic problem. Potentially, this problem might be solved with an elemental detection method such as LIBS combined with a molecular detection method. Laser-induced fluorescence (LIF) might be a candidate for the detection of small molecules, but for larger polyatomic molecules, the resulting fluorescence is often spread between many states and too weak for molecular detection at concentrations of interest. Simple molecules and radicals that results from high temperature combustion and plasma-interaction processes, on the other hand, are known to be readily and sensitively detected with LIF. We hypothesize that such molecular radicals will exist in the perimeter of the LIBS plasma, and can in those locations be accessed with LIF, providing orthogonal detection inside the LIBS event itself. Physical Sciences Inc. and the University of California at San Diego hereby propose to examine the potential of using LIF in the perimeter of a LIBS plasma. We will make use of the spectral information gathered during this program to develop a design for a simple LIF system that can be added to instruments like the Man-Portable (MP) LIBS system now under development by ARL and Ocean Optics Inc.