Laser Induced Breakdown Spectroscopy for Classification of High Energy Materials using Elemental Intensity Ratios

Gundawar, Manoj Kumar; Rao, S. Venugopal

doi:10.14429/dsj.64.4741

Cited by 18 publications

(9 citation statements)

References 37 publications

(42 reference statements)

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“…According to their data, the formation of CN from atomic C (or a species with a single C atom) was a more viable option. Our recent studies 62,63 on some inorganic and organic explosives clearly suggests that by simply using the simple intensity ratios of the atomic and molecular species one-dimensional, two-dimensional, and three-dimensional models can be developed that could be used effectively to classify or identify different explosive molecules. However, as recently pointed out by Fountain et al, 64 many more challenges remain in the discrimination of energetic materials and many more methodologies need to be developed and discovered for us to arrive at a foolproof and robust technique for the identification of explosives.…”

Section: Resultsmentioning

confidence: 99%

Femtosecond Laser-Induced Breakdown Spectroscopy Studies of Nitropyrazoles: The Effect of Varying Nitro Groups

Rao

Soma

2015

Appl Spectrosc

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The technique of femtosecond laser-induced breakdown spectroscopy (FLIBS) was employed to investigate seven explosive molecules of nitropyrazole in three different atmospheres: ambient air, nitrogen, and argon. The FLIBS data illustrated the presence of molecular emissions of cyanide (CN) violet bands, diatomic carbon (C2) Swan bands, and atomic emission lines of C, H, O, and N. To understand the plasma dynamics, the decay times of molecular and atomic emissions were determined from time-resolved spectral data obtained in three atmospheres: air, argon, and nitrogen. The CN decay time was observed to be longest in air, compared to nitrogen and argon atmospheres, for the molecules pyrazole (PY) and 4-nitropyrazole (4-NPY). In the case of C2 emission, the decay time was observed to be the longest in argon, compared to the air and nitrogen environments, for the molecules PY, 4-NPY, and 1-methyl-3,4,5-trinitropyrazole. The intensities of the CN, C2, C, H, O, and N emission lines and various molecular/atomic intensity ratios such as CN/C2, CN(sum)/C2(sum), CN/C, CN(sum)/C, C2/C, C2(sum)/C, (C2 + C) / CN, (C2(sum) + C)/CN(sum), O/H, O/N, and N/H were also deduced from the LIBS spectra obtained in argon atmosphere. A correlation between the observed decay times and molecular emission intensities with respect to the number of nitro groups, the atmospheric nitrogen content, and the oxygen balance of the molecules was investigated. The relationship among the LIBS signal intensity, the molecular/atomic intensity ratios, and the oxygen balance of these organic explosives was also explored.

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Section: Resultsmentioning

confidence: 99%

Femtosecond Laser-Induced Breakdown Spectroscopy Studies of Nitropyrazoles: The Effect of Varying Nitro Groups

Rao

Soma

2015

Appl Spectrosc

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“…The samples were irradiated by the pulses from the second harmonic of Nd: YAG laser at 532 nm, 7 ns at 1 Hz 34 . The details of the experimental setup can be found in Myakalwar 35 , et al Experiments were performed on a set of five HEMs-HMX, NTO, PETN, RDX, and TNT in ambient conditions to acquire multiple spectra.…”

Section: Methodsmentioning

confidence: 99%

An Approach to Reduce the Sample Consumption for LIBS based Identification of Explosive Materials

2017

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An experimental design based on spectral construction, which has potential to minimise the sample consumption, the number of laser shots and time required to collect the data from laser induced breakdown spectroscopy for identification of the explosive materials is reported in the study. This approach is an ideal solution in the field of hazardous material detection, where the availability of the sample can be a serious limiting factor. The experimental data recorded on a set of five high energy materials has been considered to test the performance of the proposed methodology. Multiple spectra are constructed by assuming a normal distribution at each wavelength of the spectrum, where random numbers are generated using the mean and standard deviations obtained from arbitrarily chosen five experimental spectra from each class. The newly generated spectra are called as synthetic spectra. The correct classification obtained from -K -nearest neighbour combined with principal component analysis and partial least square -discriminant analysis demonstrated very promising results. The correct classification rates differed by only 4 per cent -7 per cent as compared to conventional approach where experimental spectra alone are considered for the analysis. Further, when RDX is excluded, the obtained results are almost identical with conventional approach.

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“…The details of the experimental setup used for recording the data can be found in literature 5,8,31 , with the exception of the distance of the sample from the focussing lens. In brief, 532 nm laser pulses of 7 ns pulse duration from a Q-switched Nd: YAG were employed.…”

Section: Methodsmentioning

confidence: 99%

“…The latter being identification of the specific explosive, which can give crucial inputs to the investigators to solve a bomb blast case. Stand-off/Remote applications of LIBS has been shown to give promising results in various fields like explosive detection 8 , nuclear waste management 16 Chandrayan II has a proposed onboard LIBS sensor. While signal strength and collection combined with several advantages make LIBS a contender for future, the applications related to the identification of explosives comes with an additional challenge.…”

Section: Introductionmentioning

confidence: 99%

Standoff Detection of Explosives at 1 m using Laser Induced Breakdown Spectroscopy

Gundawar¹,

Junjuri²,

Myakalwar³

2017

Def. Sc. Jl.

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We report the 'standoff detection' of explosives at 1 m in laboratory conditions, for the first time in India, using Laser Induced Breakdown Spectroscopy combined with multivariate analysis. The spectra of a set of five secondary explosives were recorded at a distance of 1 m from the focusing as well as collection optics. The plasma characteristics viz., plasma temperature and electron density were estimated from Boltzmann statistics and Stark broadening respectively. Plasma temperature was estimated to be of the order of (10.9 ± 2.1) ×10 3 K and electron density of (3.9 ± 0.5) ×1016 cm -3 . Using a ratiometric approach, C/H and H/O ratios showed a good correlation with the actual stoichiometric ratios and a partial identification success could be achieved. Finally employing principle component analysis, an excellent classification could be attained.

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Laser Induced Breakdown Spectroscopy for Classification of High Energy Materials using Elemental Intensity Ratios

Cited by 18 publications

References 37 publications

Femtosecond Laser-Induced Breakdown Spectroscopy Studies of Nitropyrazoles: The Effect of Varying Nitro Groups

Femtosecond Laser-Induced Breakdown Spectroscopy Studies of Nitropyrazoles: The Effect of Varying Nitro Groups

An Approach to Reduce the Sample Consumption for LIBS based Identification of Explosive Materials

Standoff Detection of Explosives at 1 m using Laser Induced Breakdown Spectroscopy

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