Simultaneous Detection of Surface Traces of Nitro- and Organophosphorus Compounds

Abstract

This work continues the study of a possibility of using laser fragmentation/laser-induced fluorescence (LF/LIF) for the remote detection of nitrocompounds (NC) and organophosphorus compounds (OPC). A technique for simultaneous detection of surface traces of NС and OPС is discussed. It is experimentally shown that exciting laser radiation at a wavelength of 246.824 nm, which falls in the region of overlapping rotational lines of γ(0, 2) and γ(0, 0) bands of NO and PO absorption spectra, can be used for simultaneous excitation of fluorescence of NС and OPС photofragments. To improve the noise immunity of the LF/LIF detection technique, it is suggest to use sounding laser radiation wavelength from the range of overlapping γ(0, 2) and γ(1, 1) bands of the absorption spectra of NO and PO fragments in excited vibrational states after fragmentation. The resulting intense anti-Stokes γ(0, 1) and γ(1, 0) fluorescence bands are located in the spectral range 235–240 nm and do not overlap with the spectra of broadband Stokes fluorescence of surface materials bearing traces of NС and OPСs. The results can be used in the development of a universal system for the simultaneous detection of surface traces of explosives and toxic substances by LF/LIF method.