Effectiveness of laser sources for contactless sampling of explosives

Artem E. Akmalov; Alexander A. Chistyakov; Gennadii E. Kotkovskii

doi:10.1117/12.2222188

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3 May 2016 Effectiveness of laser sources for contactless sampling of explosives

Artem E. Akmalov, Alexander A. Chistyakov, Gennadii E. Kotkovskii

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Proceedings Volume 9823, Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XXI; 982311 (2016) https://doi.org/10.1117/12.2222188
Event: SPIE Defense + Security, 2016, Baltimore, Maryland, United States

Abstract

A mass-spectrometric study of photo processes initiated by ultraviolet (UV) laser radiation in explosives adsorbed on metal and dielectric substrates has been performed. A calibrated quadrupole mass spectrometer was used to determine a value of activation energy of desorption and a quantity of explosives desorbed by laser radiation. A special vacuumoptical module was elaborated and integrated into a vacuum mass-spectrometric system to focus the laser beam on a sample. It has been shown that the action of nanosecond laser radiation set at q= 10⁷ - 10⁸ W/cm², λ=266 nm on adsorbed layers of molecules of trinitrotoluene (TNT ) and pentaerytritoltetranitrate (PETN) leads not only to an effective desorption, but also to the non-equilibrium dissociation of molecules with the formation of nitrogen oxide NO. The cyclotrimethylenetrinitramine (RDX) dissociation products are observed only at high laser intensities (q> 109 W/cm²) thus indicating the thermal nature of dissociation, whereas desorption of RDX is observed even at q> 10⁷ W/cm² from all substrates. Desorption is not observed for cyclotetramethylenetetranitramine (HMX) under single pulse action: the dissociation products NO and NO₂ are registered only, whereas irradiation at 10Hz is quite effective for HMX desorption. The results clearly demonstrate a high efficiency of nanosecond laser radiation with λ = 266 nm, q ~ 10⁷ - 10⁸ W/cm², E_pulse= 1mJ for desorption of molecules of explosives from various surfaces.

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Artem E. Akmalov, Alexander A. Chistyakov, and Gennadii E. Kotkovskii "Effectiveness of laser sources for contactless sampling of explosives", Proc. SPIE 9823, Detection and Sensing of Mines, Explosive Objects, and Obscured Targets XXI, 982311 (3 May 2016); https://doi.org/10.1117/12.2222188

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