A study of the composition of the products of laser-induced breakdown of hexogen, octogen, pentrite and trinitrotoluene using selected ion flow tube mass spectrometry and UV-Vis spectrometry

J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejskova 3, 182 23 Prague 8, Czech Republic.
The Analyst (Impact Factor: 4.11). 05/2010; 135(5):1106-14. DOI: 10.1039/b926425f
Source: PubMed


Four types of explosives were studied using a combination of Laser Induced Breakdown Spectroscopy (LIBS) and Selected Ion Flow Tube Mass Spectrometry (SIFT-MS). The LIBS technique uses short laser pulses (ArF excimer laser) as the energy source to convert small amounts samples into plasma and to produce the emission from their molecular fragments or atoms. SIFT-MS is a novel method for absolute quantification based on chemical ionization using three precursor ions, with the capability to determine concentrations of trace gases and vapours of volatile organic compounds in real time. This is the first time that SIFT-MS has been used to study the release of NO, NO(2), HCN, HNO(3), HONO, HCHO and C(2)H(2) after a laser-induced breakdown of pure explosive compounds HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclo-octane), RDX (1,3,5-trinitro-2-oxo-1,3,5-triazacyclo-hexane), PETN (pentaerithrityl-tetranitrate) and TNT (2,4,6-trinitrotoluene) in solid form. The radiation emitted after excitation was analysed using a time resolving UV-Vis spectrometer with a ICCD detector. Electronic bands of the CN radical (388 nm), the Swan system of the C(2) radical (512 nm), the NH radical (336 nm), the OH radical (308.4 nm) and atomic lines of oxygen, nitrogen and hydrogen were identified. Vibrational and excitation temperatures were determined from the intensity distributions and a scheme of chemical reactions responsible for the formation of the observed species was proposed.

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    • "A few noted advantages include simultaneous multielement detection, high detection speed, requirement of small amount of material for testing, and material could be in any form. LIBS has been proved to be an attractive and versatile technique for the detection of hazardous and prohibited substances [5] [6] [7] [8] [9]. Especially, the standoff detection potential makes this technique an attractive contrivance for detection of high energy materials (HEMs)[5]. "
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    ABSTRACT: We present results from the elemental and molecular species dynamics of high energy materials (HEMs) studied using laser induced breakdown spectroscopy with femtosecond (fs) laser pulses. Spectral emission behavior of atomic and molecular species of HEMs such as NTO (3-nitro-l,2,4-triazol-5-one), TNT (tri-nitro toluene) and ANTA (5-amino-3-nitro-1H-1,2,4-triazole) were studied in different atmospheres of Argon, Nitrogen, and ambient air. We used fs pulses (~40 fs, 2.5 mJ, 1 kHz) for creating the breakdown. CN and C 2 molecular species were formed from these organic molecules during the breakdown. These molecular species are key signatures of organics substances for identification of HEMs.
    Full-text · Conference Paper · Jun 2013
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    • "Babushok et al. [47] presented a modeling of RDX LIBS plasma using several possible reactions occurring within the plasma. Sovova et al. [48] presented temporal features of CN, C 2 and C emission of four explosives in Air and Argon environments. To the best of our knowledge there are no reports till date to explain the temporal dynamics of HEMs recorded using fs pulses. "
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    ABSTRACT: Femtosecond laser induced breakdown spectroscopic (LIBS) studies were performed on three high energy materials namely 5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO), 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX), and 2,4,6-Trinitrotoluene (TNT). LIBS spectral features were obtained for these samples in three different atmospheres i.e. Air, Nitrogen, and Argon. Different molecular to elemental ratios in these three atmospheres were investigated in detail. CN/C and CN/N ratios were observed to be prominent in Nitrogen, Air atmospheres. We attempt to elucidate the role of several reactions involving CN molecular formation in connection with discrepancies obtained in the measured ratios. The complete temporal dynamics of atomic C (247.82 nm) and CN (388.20 nm) molecular species in three different atmospheres are elaborated. The decay rates of C peak were found to be longest (96 ns - 121 ns) in Argon atmosphere for all the samples. The decay rates of CN peak (388.2 nm) were longer (161 ns - 364 ns) in Nitrogen compared to Air and Argon atmospheres. We also attempt to explicate the decay mechanisms with respect to the molecular species formation dynamics in different atmospheres.
    Full-text · Article · May 2013 · Spectrochimica Acta Part B Atomic Spectroscopy
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