Molecular orbital interpretation of the ultra-violet absorption spectra of unconjugated aliphatic nitramines

Stals, J.; Barraclough, C. G.; Buchanan, A. S.

doi:10.1039/tf9696500904

Cited by 27 publications

(18 citation statements)

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“…The latter transition mainly originates from a p!p* transition. 56,57 Stals et al 57 indicate that the assignment of the ;200 nm broad band is complicated by the ''intimate mixing'' of r, p, r*, p*, and n orbitals, which are of similar energies.…”

Section: Resultsmentioning

confidence: 99%

Deep Ultraviolet Resonance Raman Excitation Enables Explosives Detection

Tuschel

Mikhonin²,

Lemoff³

et al. 2010

Appl Spectrosc

122

171

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We measured the 229 nm absolute ultraviolet (UV) Raman cross-sections of the explosives trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), cyclotrimethylene-trinitramine (RDX), the chemically related nitroamine explosive HMX, and ammonium nitrate in solution. The 229 nm Raman cross-sections are 1000-fold greater than those excited in the near-infrared and visible spectral regions. Deep UV resonance Raman spectroscopy enables detection of explosives at parts-per-billion (ppb) concentrations and may prove useful for stand-off spectroscopic detection of explosives.

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Section: Resultsmentioning

confidence: 99%

Deep Ultraviolet Resonance Raman Excitation Enables Explosives Detection

Tuschel

Mikhonin²,

Lemoff³

et al. 2010

Appl Spectrosc

122

171

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show abstract

“…4 and 5 (curve 2) are the TNT and RDX absorption profiles respectively obtained with the spectrophotometer. Bands near 240 nm are attributed to the 1 B 2 -1 A 1 transition and are mainly due to the π * ← π and π * ← n transition localized in -NO 2 functional groups [14][15][16]. In addition, three other transitions arising due to the nitro group occur in the 203, 255, and 271 nm regions, of which only the 255 nm band is covered by the scan region of our laser spectrophotometer appearing as a bump, whereas two others fall beyond this region.…”

Section: Discussionmentioning

confidence: 99%

Generation of coherent tunable deep UV radiation for detection and absorption studies of explosives RDX and TNT

et al. 2007

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We report a technique for the efficient generation of tunable coherent deep UV radiation and its application in studies of RDX and TNT at the ppm level on the basis of their absorption characteristics. The obtained experimental absorption data are compared with conventional spectrophotometric data. The UV radiation in the range 200-260 nm has been generated by the type-I noncollinear third harmonic of the dye laser radiation (600-700 nm) and also by sum frequency mixing (SFM) of Nd:YAG output (1064 nm) with the second harmonic of the dye laser in β-barium borate (BBO) crystal. The maximum conversion efficiency of the generated signal is estimated to be 57.5% at λ = 218.9 nm wavelength. Apart from measurements of the absorbance of RDX and TNT at different concentrations in their respective solutions, the minimum detection concentrations have also been ascertained. The estimated minimum detectable concentration of RDX is 8.47⋅10 -9 M, whereas that for TNT is 35.7⋅10 -9 M. The data were obtained using only ~100 µJ/pulse of laser energy.Introduction. Explosives are chemical compounds or their mixtures capable of storing large amounts of energy in a compact form and subsequently releasing large volumes of hot gases when exploded [1]. Their illegal use by criminals and extremist groups has reached an alarming level. In addition, some slightly water-soluble explosives such as TNT (0.01 % at 298 K), are responsible for contamination of groundwater, thus threatening public health. These problems have attracted global attention towards developing sensitive detection and identification techniques capable of assisting law enforcement agencies in detecting the explosives at various crowded public places such as airports, theatres, railway stations, etc. For forensic purposes, investigation of bomb blast sites requires not only sensitive detection of submicrogram levels but also specific identification techniques for different explosive components in an exhibited sample. Lasers have made studies of explosives possible under controlled conditions. Several laser-based effects which occur in different regions of optical spectrum such as opto-acoustic effect and multi-photon dissociation [2,3] in the IR region, desorption in the visible region, and photochemical, photothermal, photoablation and laser-induced fluorescence effects in the UV region [4,5] have been exploited to detect and identify explosives. FTIR absorption/transmission curves of explosives provide useful information about different functional groups. The absorption peak located near 6 µm is due to the presence of the -NO 2 group; it has been recognized as a characteristic peak of all secondary explosives.Here we report the study of transmission/absorption characteristics of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT) for the first time by using deep UV radiation tunable in the range 200-260 nm, which was generated by sum frequency mixing (SFM) of a tunable dye-laser output with that of Nd:YAG laser in a β-barium borate (BBO) crystal.

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“…Following the above reaction sequence one would intuitively expect this reaction to be part of the decomposition of nitramide (H2NNO2) , which is known to yield N20 and H20 [90][91][92][93][94][95][96][97].…”

Section: D3ch2conomentioning

confidence: 99%