Femtosecond and nanosecond laser induced breakdown spectroscopic studies of NTO, HMX, and RDX

Gundawar, Manoj Kumar; Myakalwar, Ashwin Kumar; Kiran, P. Prem; Tewari, Surya P.; Rao, S. Venugopal

doi:10.1016/j.sab.2012.11.002

Cited by 60 publications

(30 citation statements)

References 64 publications

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“…A study of LIBS spectra of NTO, HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), and RDX in air atmosphere using fs-Nd:YLF (800 nm, ∼40 fs FWHM, ∼2.5 mJ, 1 kHz) and ns-Nd:YAG (532 nm, 6 ns FWHM, ∼600 mJ, 10 Hz) pulses revealed that C, H, N, O, and CN atomic and molecular emissions typically persisted for a few tens of nanoseconds in the fs-Nd:YLF case, and a few hundred nanoseconds in the ns-Nd:YAG case. 196 However, the authors observed that the ratios of the CN peaks (388.28, 387.08, and 386.16 nm) to the C peak (247.82 nm) in LIBS spectra recorded with similar fluences was higher for the fs laser compared to the ns laser. In the same vein, strong signatures corresponding to emissions from molecular species in the case of fs-Ti:sapphire (800 nm, ∼50 fs, ∼1 mJ) excitation, and atomic species for ns-Nd:YAG (532 nm, ∼7 ns, ∼25 mJ, 10 Hz) excitation, were observed in LIBS spectra of seven nitroimidazoles (novel explosive molecules) in both air and argon atmospheres.…”

Section: Influence Of Excitation Variablesmentioning

confidence: 96%

Laser-Induced Breakdown Spectroscopy (LIBS) of Organic Compounds: A Review

Moros

Laserna

2019

Appl Spectrosc

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Optical emission of laser-produced plasmas from solids, liquids, and gases, from their fundamentals to their potential applications, has been comprehensively reported in multiple research manuscripts, reviews, and books. There are nevertheless enough serious unanswered issues and questions still present on what at first sight seemed to be much easier, the laser-induced breakdown spectroscopy (LIBS) of organic compounds. Ideally, for all organic molecules, one would expect homologous emission spectra, differing only in the presence or absence of signals associated to the containing elements and their intensity relative to their content. Yet, the reality is much more complex. In laser-induced plasmas of organic compounds, a broad variety of species may be formed depending on the irradiation parameters. Furthermore, there is not a uniform breakage for all the molecules constituting the ablated mass. At once, the plasma is a dynamic entity per se, which implies that the spatial distribution of each species in the source plasma is different. In addition, multiple circumstances and mechanisms may contribute to the extinction of some species and the formation of new ones. Thus, the surrounding atmosphere where the plasma evolves and the time elapsed from its formation also have a strong influence on the spectral signature gathered. In essence, any change in any of the variables involved in the cycle of an organic plasma, from those causing its formation to those governing its expansion, defines a new scenario that lead to a different LIBS spectrum for a same organic compound. The present paper reviews the common emitting species populating the laser plasmas of organic compounds, the routes to their formation, mostly those related to the production of diatomic radicals, the dynamics of such species, in space and time, and the physical parameters that they confer to the plasma. Concurrently, the influence that the structures of the molecular solids and the set of excitation variables may exert on the optical emissions observed is also discussed. Finally, some details on the modeling of organic plasmas are provided.

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Section: Influence Of Excitation Variablesmentioning

confidence: 96%

Laser-Induced Breakdown Spectroscopy (LIBS) of Organic Compounds: A Review

Moros

Laserna

2019

Appl Spectrosc

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“…Moreover, in LPP, the input pulse duration [15] as well as the focusing conditions [53] significantly influence the persistence of plasma species. Comparative ns and fs LIBS studies of TNT residue on Al substrate by Dikmelik et al [68] have again illustrated that lower background signal from substrate is observed in case of fs pulses with CN and C 2 being identified as markers for explosives whereas C, H, N, O atomic lines were suggested as markers in case of ns pulses.…”

Section: Standoff Libs Studies Of Nitroimidazolesmentioning

confidence: 99%

“…In contrast, laser based spectroscopic techniques such as Raman spectroscopy, laser induced breakdown spectroscopy (LIBS), terahertz spectroscopy and laser induced fluorescence possess high potential for in situ remote/standoff detection of explosives, biological warfare agents and hazardous substances [3][4][5][6][7][8][9]. Laser induced breakdown spectroscopy has been extensively used in various fields owing to it's robust in situ elemental analysis, such as space exploration, pharmaceutical, soil and nutrient analysis and identification/discrimination of explosives [10][11][12][13][14][15][16][17][18]. To this end, nanosecond (ns) LIBS has been extensively used in analysing aerosols [19], process control and monitoring in metallurgical industry [20], planetary missions and detection of explosive residues [21][22][23][24] [29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Femtosecond laser induced breakdown spectroscopy based standoff detection of explosives and discrimination using principal component analysis

et al. 2018

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We report the standoff (up to ~2 m) and remote (~8.5 m) detection of novel high energy materials/explosive molecules (Nitroimidazoles and Nitropyrazoles) using the technique of femtosecond laser induced breakdown spectroscopy (LIBS). We utilized two different collection systems (a) ME-OCT-0007 (commercially available) and (b) Schmidt-Cassegrain telescope for these experiments. In conjunction with LIBS data, principal component analysis was employed to discriminate/classify the explosives and the obtained results in both configurations are compared. Different aspects influencing the LIBS signal strength at far distances such as fluence at target, efficiency of collection system etc. are discussed.

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“…However, there are few reports on LIBS studies using femtosecond pulses in general, and for high-energy materials (HEMs) in particular. 23–29 Femtosecond LIBS (FLIBS) offers the advantages of, among others, a low breakdown threshold, minimal atmospheric interference, and the possibility of delivering pulses very long distances through filamentation. 10,30 Zhang et al 31 studied ablation and ionization for elemental determination and successfully demonstrated that the matrix effects are significantly reduced (by 50%) when using femtosecond pulses compared to nanosecond pulses.…”

Section: Introductionmentioning

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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Femtosecond and nanosecond laser induced breakdown spectroscopic studies of NTO, HMX, and RDX

Cited by 60 publications

References 64 publications

Laser-Induced Breakdown Spectroscopy (LIBS) of Organic Compounds: A Review

Laser-Induced Breakdown Spectroscopy (LIBS) of Organic Compounds: A Review

Femtosecond laser induced breakdown spectroscopy based standoff detection of explosives and discrimination using principal component analysis

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

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