Laser-induced fluorescence of photodissociation products of liquid-drop triethyl phosphate on a surface
S.M. Bobrovnikov1,2, E.V. Gorlov1,2, V.I. Zharkov1, S.N. Murashko1,2
1V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
2National Research Tomsk State University, Tomsk, Russia
Keywords: organophosphate, trace, laser fragmentation, phosphorus oxide, PO-fragments, laser-induced fluorescence
Abstract
The paper demonstrates possibility of remote detection of surface traces of organophosphates using the double-pulse laser fragmentation/laser-induced fluorescence (LP/LIF) method. For drop-liquid traces of triethyl phosphate on a paper surface, it is shown that the process of formation of characteristic PO fragments (phosphorus oxide molecules) of organophosphates is inertial. The formation of the maximum concentration of fragments is observed approximately 2 ms after the action of a fragmenting laser pulse (266 nm). It is found that a delay between a laser pulse (247.78 nm) a fragmenting pulse of 2 ms leads to a multiple increase in the fluorescence intensity: approximately 7 times compared to the single-pulse excitation method and approximately 2.3 times compared to simultaneous double-pulse action. The results, first, demonstrate a possibility of remote detection of surface traces of organophosphates in a condensed state by the two-pulse LF/LIF method; second, they show the need to organize optimal conditions for laser exposure to increase the efficiency of the LF/LIF process.
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