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

Abstract

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.

LIBS Detection of Explosives in Traces

“…However, in vacuum the emission is also very weak. The reason of this behavior may be explained under the hypothesis that excited atomic species experience two-body reactions with molecular species inside the plasma resulting in dissociation of such fragments through the following reactions [14]:…”

Fast detection of triacetone triperoxide (TATP) from headspace using planar solid-phase microextraction (PSPME) coupled to an IMS detector

“…Liquid chromatography [8] and gas chromatography (GC) [9] are used for the separation of TATP, and infrared [6] and Raman spectroscopy [6,10] techniques have been used to detect TATP in the laboratory. In addition, TATP can also be detected by either mass spectrometry which includes desorption electrospray ionization [11] and selected ion flow tube [12] or sensor-based techniques such as luminescence [13,14], electrochemical [15][16][17], and biological [18] sensors. However, very few of these techniques can fully accomplish two important detection requirements: fast on-site analysis with unambiguous identification and low limits of detection from post-explosion debris with high selectivity.…”

Recent SIFT-MS Studies of Volatile Compounds in Physiology, Medicine and Cell Biology

“…Much work has now been carried out in these areas, which demonstrates the value and potential of SIFT-MS, as reported in the cited references. 28,29 These wider applications of SIFT-MS and the key results obtained have been summarized in previous review papers, 30,31 while the historical development of SIFT-MS and subsequent applications are summarized in a quite recent review. 28,29 These wider applications of SIFT-MS and the key results obtained have been summarized in previous review papers, 30,31 while the historical development of SIFT-MS and subsequent applications are summarized in a quite recent review.…”