Experimental evaluation of the efficiency of approaches for excitation of anti-Stokes fluorescence of PO-photofragments of organophosphates from the first excited vibrational state X2Π (v'' = 1)
S.M. Bobrovnikov, E.V. Gorlov, V.I. Zharkov, S.N. Murashko
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: organophosphates trace, laser fragmentation, phosphorus oxide, PO-fragment, laser-induced fluorescence
Abstract
The paper discusses approaches to increasing the background immunity of the laser fragmentation/laser-induced fluorescence (LF/LIF) method in remote detection of surface traces of organophosphates. The possibility of inducing anti-Stokes fluorescence of PO-fragments (phosphorus oxide molecules) of organophosphates from the first excited vibrational state X 2Π ( v'' = 1) to the electronically excited state A 2Σ+ ( v' = 0) by laser radiation at wavelengths of 253.891, 254.021, 255.337, and 255.484 nm near the bandheads of the branches ( Q 11 + P 21), P 11, ( P 22 + Q 12), and P 12, respectively, was experimentally shown. Using the example of drop-liquid traces of triethyl phosphate on a paper surface, it was determined that excitation of P 12 branch lines forming the bandhead ensures the highest background immunity of the LF/LIF method for detecting organophosphates. The results can be used to select the optimal method for excitation of fluorescence of PO-fragments in the practical implementation of the LF/LIF method for remote detection of organophosphate traces.
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