On the Fragmentation of Nitrobenzene and Nitrotoluenes Induced by a Femtosecond Laser at 375 nm

Kosmidis, C.; Ledingham, K. W. D.; Kılıç, Hamdi Şükür; McCanny, T.; Singhal, R.P.; Langley, A. J.; Shaikh, W.

doi:10.1021/jp963187i

Cited by 98 publications

(120 citation statements)

References 45 publications

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“…These results agree well with femtosecond measurements of Kosmidis et al [25] at 375 and 750 nm, and those of Ledingham et al [24] at 375 nm. The results of this study, and that of Tasker et al [28], differ considerably in the relative amounts of…”

Section: M-nitrotoluenesupporting

confidence: 92%

“…It seems that if MPI is to be assumed the dominant ionization mechanism (or AID: absorption-ionization-dissociation, using the nomenclature of Levis [15]), then the process is much more consistent with four-or five-photon ionization. In this fashion, the factor of n ϭ 2.2 from the power dependence of the ion signal from the study of Kosmidis et al [25] could be interpreted as resulting from a two-photon transition to the intermediate state followed by a two-or three-photon transition to the ion state in a (2 ϩ 2) or (2 ϩ 3) MPI process. The gas-phase absorption spectrum of NB supports this assumption [40].…”

Section: Nitrobenzenementioning

confidence: 96%

See 1 more Smart Citation

Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds

Mullen

Coggiola

Oser

2009

J. Am. Soc. Mass Spectrom.

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The ultrafast laser-induced photoionization and photodissociation processes of the nitroaromatic containing explosive and explosive related compounds (ERCs) nitrobenzene (NB), 1,3-dinitrobenzene (DNB), m-nitrotoluene (MNT), 2,4-dinitrotoluene (DNT), and 2,4,6-trinitrotoluene (TNT) have been investigated at three laser wavelengths and power densities using a time-of-flight mass spectrometer. Examination of the mass spectra of these compounds reveals the enhanced formation of the molecular ion [M ϩ ] when ultraviolet (332 nm) and visible (495 nm) light is used relative to infrared (795 nm) radiation. In addition, at 795 nm and a power density of 3.5 ϫ 10 14 W/cm 2 , the presence of a competition between multiphoton ionization (MPI) and Coulomb explosion (CE) channels is revealed by peak shape analysis, and is thought to be operative under these conditions for all of the molecules investigated. [5][6][7][8][9][10][11][12], and polyatomic aromatic organic molecules [13][14][15][16][17][18][19][20][21][22][23], has been the subject of intense investigation. These studies have focused on the fundamental interaction of the laser pulse with the atomic or molecular system, and have generally found a number of operative ionization and dissociation mechanisms present, which are sensitive to the laser wavelength and power density. In addition, a number of studies have also been dedicated to the investigation of the analytical usefulness of femtosecond laser ionization toward molecular specific detection. A prime example is the application to the ionization and detection of the explosives and explosives related compounds pioneered by . Their studies focused on an understanding of the mass spectra obtained using ultrafast laser pulses in conjunction with time-of-flight mass spectrometry, M ϩ ion formation, and specific molecular fragments that could be assigned to a particular precursor species. Of particular interest was the demonstration of isomer dependent mass spectra for the three isomers of nitrotoluene.The motivation to apply femtosecond laser ionization to the study of explosives and ERCs originated from previous laser ionization work, which found that nanosecond laser ionization in the ultraviolet led to extensive molecular fragmentation [31][32][33][34][35][36]. The extensive fragmentation was determined to be non-useful for species-specific identification, even though abundant NO ϩ ions were observed in the mass spectra [37]. The presence of NO ϩ in the mass spectra of these species naturally raised questions regarding its formation. Mechanistically, it was discovered that the dissociative lifetimes of the intermediate states involved in the ionization process were about a few hundred femtoseconds, and that this rapid dissociation led to the extensive fragmentation observed in the mass spectra. Further, the presence of NO ϩ in the mass spectra of these species was attributed to rapid dissociation of the parent molecule (RNO 2 ) producing the NO 2 fragment. The NO 2 molecule undergoes an additional photon absorptio...

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Section: M-nitrotoluenesupporting

confidence: 92%

Section: Nitrobenzenementioning

confidence: 96%

Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds

Mullen

Coggiola

Oser

2009

J. Am. Soc. Mass Spectrom.

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“…It will populate an excited state that can either couple to a reaction pathway, resulting [19]. Many investigations have been conducted concerning the mechanism of decomposition of explosives under laser irradiation [20][21][22].…”

Section: Laser-induced Time Of Flight Mass Spectroscopy Of Typical Enmentioning

confidence: 99%

Laser Ablation of Energetic Materials

Shen¹,

Wu²,

Zhang³

et al. 2017

Laser Ablation - From Fundamentals to Applications

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The initiation of explosives by laser is a new initiation method. Compared with traditional initiation methods, laser initiation has the characteristics of high reliability and high safety. It can be used as one of the alternative technologies for future initiation device. A microscopic understanding of the complex physical and chemical processes involved in the reaction process is essential for laser initiation. Shock initiation technology of laser-driven flyer was studied. Several typical laser-driven flyer targets researches were introduced. Some significant characteristics including velocity and impact stress of flyers were tested via photonic Doppler velocimetry and polyvinylidene fluoride pressure sensor, respectively. Some types of flyers including Al and Cu single-layer flyers and CuO/Cu, CuO/Al, and CuO/Al/ Cu multilayer flyers with relatively high velocities were used to initiate PETN explosive. In order to give a better understanding of the mechanism of laser interaction with typical energetic materials (RDX, HMX, TNT, and HNS), a time of flight mass spectrometer (TOFMS) was used to detect the positive ions and the negative ions were produced in the laser-induced dissociation processes. The influences of laser wavelength, the laser fluence, and the delay time of the decomposition process have been studied as well. The results may throw some light on the laser interaction mechanism of energetic materials.

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“…Kosmidis et al compared 90-fs photodissociation of NB and NT isomers at 375 nm to 10-ns photodissociation at the same wavelength (183). They demonstrated that only the femtosecond laser produced parent and heavy mass peaks (figure 18).…”

Section: Femtosecond Ionization/dissociationmentioning

confidence: 99%

Laser-Based Detection Methods for Explosives

Munson¹,

Gottfried²,

Lucia³

et al. 2007

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On the Fragmentation of Nitrobenzene and Nitrotoluenes Induced by a Femtosecond Laser at 375 nm

Cited by 98 publications

References 45 publications

Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds

Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds

Laser Ablation of Energetic Materials

Laser-Based Detection Methods for Explosives

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