1
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DFT/TDDFT investigation on the D–π–A type molecule probes 4-(5-R-thiophen-2-yl)-2-isobutyl-2H-[1,2,3]triazolo[4,5-e][1,2,4] triazolo[1,5-a]pyrimidines: fluorescence sensing mechanism and roles of weak interactions. Theor Chem Acc 2019. [DOI: 10.1007/s00214-019-2520-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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2
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Li A, Imasaka T, Imasaka T. Optimal Laser Wavelength for Femtosecond Ionization of Polycyclic Aromatic Hydrocarbons and Their Nitrated Compounds in Mass Spectrometry. Anal Chem 2018; 90:2963-2969. [DOI: 10.1021/acs.analchem.8b00125] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Adan Li
- College
of Environmental and Chemical Engineering, Yanshan University, 438 Hebei Street, Qinhuangdao 066004, China
- Division
of International Strategy, Center of Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Tomoko Imasaka
- Department
of Environmental Design, Graduate School of Design, Kyushu University, 4-9-1
Shiobaru, Minami-ku, Fukuoka 815-8540, Japan
| | - Totaro Imasaka
- Division
of International Strategy, Center of Future Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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3
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Cooper JK, Grant CD, Zhang JZ. Experimental and TD-DFT Study of Optical Absorption of Six Explosive Molecules: RDX, HMX, PETN, TNT, TATP, and HMTD. J Phys Chem A 2013; 117:6043-51. [DOI: 10.1021/jp312492v] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Jason K. Cooper
- Department of Chemistry
and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Christian D. Grant
- Physical and Life Sciences,
Chemical Sciences Division, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California
94550, United States
| | - Jin Z. Zhang
- Department of Chemistry
and Biochemistry, University of California, Santa Cruz, California 95064, United States
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4
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White JD, Akin FA, Oser H, Crosley DR. Production of the NO photofragment in the desorption of RDX and HMX from surfaces. APPLIED OPTICS 2011; 50:74-81. [PMID: 21221163 DOI: 10.1364/ao.50.000074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A promising scheme for the remote detection of nitrate-based explosives, which have low vapor pressure, involves two lasers: the first to desorb, vaporize, and photofragment the explosive molecule and the second to create laser-induced fluorescence in the NO fragment. It is desirable to use for the first a powerful 532 nm frequency-doubled Nd:YAG laser. In this study, we investigate the degree of photofragmentation into NO resulting from the irradiation of the explosives RDX and HMX coated on a variety of surfaces. The desorption step is followed by femtosecond laser ionization and time-of-flight mass spectrometry to reveal the fragments produced in the first step. We find that modest laser power of 532 nm desorbs the explosive and produces adequate amounts of NO.
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Affiliation(s)
- Jason D White
- Molecular Physics Laboratory, SRI International, Menlo Park, California 94025, USA.
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5
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Li A, Uchimura T, Watanabe-Ezoe Y, Imasaka T. Analysis of Dioxins by Gas Chromatography/Resonance-Enhanced Multiphoton Ionization/Mass Spectrometry Using Nanosecond and Picosecond Lasers. Anal Chem 2010; 83:60-6. [DOI: 10.1021/ac101849w] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Adan Li
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan, and College of Chemistry and Environmental Engineering, Yanshan University, Qinhuangdao 066004, China
| | - Tomohiro Uchimura
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan, and College of Chemistry and Environmental Engineering, Yanshan University, Qinhuangdao 066004, China
| | - Yuka Watanabe-Ezoe
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan, and College of Chemistry and Environmental Engineering, Yanshan University, Qinhuangdao 066004, China
| | - Totaro Imasaka
- Department of Applied Chemistry, Graduate School of Engineering, and Division of Translational Research, Center for Future Chemistry, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan, and College of Chemistry and Environmental Engineering, Yanshan University, Qinhuangdao 066004, China
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6
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Headrick JM, Reichardt TA, Settersten TB, Bambha RP, Kliner DAV. Application of laser photofragmentation-resonance enhanced multiphoton ionization to ion mobility spectrometry. APPLIED OPTICS 2010; 49:2204-2214. [PMID: 20390024 DOI: 10.1364/ao.49.002204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We demonstrate detection of nitro-containing compounds with laser photofragmentation (PF) coupled with resonance enhanced multiphoton ionization (REMPI) and ion mobility spectrometry (IMS). In PF-REMPI, a laser dissociates the parent molecules, producing fragments that can then be ionized by absorption of additional laser photons. The production of these ions strongly depends on the wavelength of laser light, with ion yields corresponding to the absorption spectrum of the fragments [nitric oxide (NO) in the present case]. Combining IMS with PF-REMPI provides further specificity, separating ions according to their mobilities through an atmospheric-pressure drift tube. In this work, we use a pulsed UV laser to examine the characteristics of atmospheric-pressure PF-REMPI, the chemistry occurring in the ionization region and drift tube, and the viability of detecting ions created by both resonance-enhanced and nonresonant ionization. Probing NO in a helium-nitrogen bath, we demonstrate that the detection of ions displays single-shot response to changes in ion generation, with an ion extraction-to-collection efficiency of approximately 12%. We then evaluate the sensitivity and specificity of PF-REMPI/IMS as applied to the detection of both the explosive surrogate 2, 4-dinitrotoluene and the nuisance compound nitrobenzene.
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Affiliation(s)
- Jeffrey M Headrick
- Sandia National Laboratories, P.O. Box 969, MS 9056, Livermore, California 94551, USA
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7
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Yamaguchi S, Uchimura T, Imasaka T, Imasaka T. Gas chromatography/time-of-flight mass spectrometry of triacetone triperoxide based on femtosecond laser ionization. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2009; 23:3101-3106. [PMID: 19705378 DOI: 10.1002/rcm.4225] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Triacetone triperoxide (TATP), which is used as an explosive in acts of terrorism, was measured by means of gas chromatography/multiphoton ionization/time-of-flight mass spectrometry using a deep-ultraviolet (deep-UV) femtosecond laser as an ionization source. The fragmentation process was investigated by changing the intensity of the laser at the center axis of a molecular beam. A molecular ion was observed using a femtosecond laser, and the ratio of the intensities of the molecular and fragment ions decreased as the intensity of the laser increased. These results suggest that TATP can be efficiently ionized using a deep-UV, ultrashort optical pulse. Furthermore, fragmentation was accelerated by excess energy supplied through higher-order multiphoton processes under a strong radiation field. The detection limits obtained using the molecular ion and two dominant fragment ions, C(2)H(3)O(+) and CH(3) (+), were determined to be 670, 83 and 150 pg, respectively.
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Affiliation(s)
- Satoshi Yamaguchi
- Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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8
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Mullen C, Coggiola MJ, Oser H. Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:419-429. [PMID: 19036604 DOI: 10.1016/j.jasms.2008.10.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 10/28/2008] [Accepted: 10/31/2008] [Indexed: 05/27/2023]
Abstract
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(+)] 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 x 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.
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Affiliation(s)
- Christopher Mullen
- Molecular Physics Laboratory, SRI International, Menlo Park, California 94025, USA
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9
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Yamaguchi S, Kira F, Miyoshi Y, Uchimura T, Watanabe-Ezoe Y, Zaitsu SI, Imasaka T, Imasaka T. Near-ultraviolet femtosecond laser ionization of dioxins in gas chromatography/time-of-flight mass spectrometry. Anal Chim Acta 2009; 632:229-33. [DOI: 10.1016/j.aca.2008.11.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 10/25/2008] [Accepted: 11/02/2008] [Indexed: 11/16/2022]
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10
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11
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Ramos C, Dagdigian PJ. Effect of photochemistry on molecular detection by cavity ringdown spectroscopy: case study of an explosive-related compound. APPLIED OPTICS 2007; 46:6526-32. [PMID: 17846646 DOI: 10.1364/ao.46.006526] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Explosives and explosive-related compounds usually have dissociative excited electronic states. We consider the effect of excited-state dissociation upon an absorption event on the UV cavity ringdown spectroscopy (CRDS) detection of these molecules. A change in the photon decay lifetime with increasing laser energy is demonstrated with vapors of 2,6-dinitrotoluene in the open atmosphere. The magnitude of the effect is modeled with coupled equations describing the time-dependent light intensity and molecular concentration within the cavity. The light intensities required within this model to explain the observed changes in the photon decay lifetimes are consistent with the light intensities expected within the cavity under our experimental conditions. It was also found that the slow diffusion of the molecules in static air can magnify the effect of photochemistry on UV CRDS trace detection of molecules with dissociative excited states.
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Affiliation(s)
- Christopher Ramos
- Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218-2685, USA
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12
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Lin MF, Lee YT, Ni CK, Xu S, Lin MC. Photodissociation dynamics of nitrobenzene and o-nitrotoluene. J Chem Phys 2007; 126:064310. [PMID: 17313218 DOI: 10.1063/1.2435351] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Photodissociation of nitrobenzene at 193, 248, and 266 nm and o-nitrotoluene at 193 and 248 nm was investigated separately using multimass ion imaging techniques. Fragments corresponding to NO and NO(2) elimination from both nitrobenzene and o-nitrotoluene were observed. The translational energy distributions for the NO elimination channel show bimodal distributions, indicating two dissociation mechanisms involved in the dissociation process. The branching ratios between NO and NO(2) elimination channels were determined to be NONO(2)=0.32+/-0.12 (193 nm), 0.26+/-0.12 (248 nm), and 0.4+/-0.12(266 nm) for nitrobenzene and 0.42+/-0.12(193 nm) and 0.3+/-0.12 (248 nm) for o-nitrotoluene. Additional dissociation channels, O atom elimination from nitrobenzene, and OH elimination from o-nitrotoluene, were observed. New dissociation mechanisms were proposed, and the results are compared with potential energy surfaces obtained from ab initio calculations. Observed absorption bands of photodissociation are assigned by the assistance of the ab initio calculations for the relative energies of the triplet excited states and the vertical excitation energies of the singlet and triplet excited states of nitrobenzene and o-nitrotoluene. Finally, the dissociation rates and lifetimes of photodissociation of nitrobenzene and o-nitrotoluene were predicted and compared to experimental results.
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Affiliation(s)
- Ming-Fu Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan
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13
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He Y, Gahlmann A, Feenstra JS, Park ST, Zewail AH. Ultrafast Electron Diffraction: Structural Dynamics of Molecular Rearrangement in the NO Release from Nitrobenzene. Chem Asian J 2006; 1:56-63. [PMID: 17441038 DOI: 10.1002/asia.200600107] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Nitro compounds release NO, NO2, and other species, but neither the structures during the reactions nor the time scales are known. Ultrafast electron diffraction (UED) allowed the study of the NO release from nitrobenzene, and the molecular pathways and the structures of the transient species were identified. It was observed, in contrast to previous inferences, that nitric oxide and phenoxyl radicals are formed dominantly and that the time scale of formation is 8.8+/-2.2 ps. The structure of the phenoxyl radical was determined for the first time, and found to be quinoid-like. The mechanism proposed involves a repulsive triplet state, following intramolecular rearrangement. This efficient generation of NO may have important implications for the control of by-products in drug delivery and other applications.
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Affiliation(s)
- Yonggang He
- Laboratory for Molecular Science and Physical Biology Center for Ultrafast Science and Technology, California Institute of Technology, Pasadena, CA 91125, USA
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14
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Mullen C, Irwin A, Pond BV, Huestis DL, Coggiola MJ, Oser H. Detection of Explosives and Explosives-Related Compounds by Single Photon Laser Ionization Time-of-Flight Mass Spectrometry. Anal Chem 2006; 78:3807-14. [PMID: 16737241 DOI: 10.1021/ac060190h] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The application of single photon ionization in combination with mass-selective detection by time-of-flight mass spectrometry is described for the rapid detection of the nitro-containing explosives and explosives-related compounds nitrobenzene, 1,3-dinitrobenzene, o-nitrotoluene, 2,4-dinitrotoluene, and 2,4,6-trinitrotoluene, as well as the peroxide-based explosive triacetone triperoxide in the gas phase. The technique is demonstrated to be a plausible approach for laser-based rapid detection of explosives. The limits of detection for nitrobenzene and 2,4-dinitrotoluene using SPI were also measured and determined to be 17-24 (S/N approximately 2:1) and approximately 40 ppb (S/N approximately 2:1), respectively.
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Affiliation(s)
- Christopher Mullen
- Molecular Physics Laboratory, SRI International, Menlo Park, California 94025, USA
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15
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Li C, Gawandi V, Protos A, Phillips RS, Amster IJ. A matrix-assisted laser desorption/ionization compatible reagent for tagging tryptophan residues. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2006; 12:213-21. [PMID: 17057278 DOI: 10.1255/ejms.814] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Chemical tagging of amino acids is an important tool in proteomics analysis, and has been used to introduce isotope labels and mass defect labels into proteolytic peptides by derivatization of cysteine or lysine residues. Here, we present a new reagent with chemical specificity for tryptophan residues. Previously, 2-nitrobenzenesulfenyl chloride has been used as a highly specific reagent for labeling tryptophan residues. We show that this tag undergoes UV dissociation during matrix assisted laser desorption/ionization (MALDI). The multiplicity of photofragments increases the difficulty of characterizing the derivatization products. To overcome this problem, we have synthesized a new reagent, 2-(trifluoromethyl)benzenesulfenyl chloride, which is shown to react quantitatively with tryptophan in peptides and proteins. Most significantly, it exhibits high photostability in MALDI-Fourier transform mass spectrometry analyses.
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Affiliation(s)
- Chunyan Li
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
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16
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Abstract
The detection of explosives, energetic materials, and their associated compounds for security screening, demining, detection of unexploded ordnance, and pollution monitoring is an active area of research. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. This review focuses on techniques such as optical and mass spectrometry and chromatography for detection of trace amounts of explosives with short response times. We also review techniques for detecting the decomposition fragments of these materials. Molecular data for explosive compounds are reviewed where available.
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Affiliation(s)
- J I Steinfeld
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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17
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Li YM, Sun JL, Yin HM, Han KL, He GZ. Photodissociation of nitrobenzene at 266 nm: Experimental and theoretical approach. J Chem Phys 2003. [DOI: 10.1063/1.1557932] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Weickhardt C, Tönnies K. Short pulse laser mass spectrometry of nitrotoluenes: ionization and fragmentation behavior. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2002; 16:442-446. [PMID: 11857729 DOI: 10.1002/rcm.567] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The mass spectra of all isomers of mononitrotoluene, four isomers of dinitrotoluene and of 2,4,6,-trinitrotoluene, obtained by multiphoton ionization utilizing ultrashort laser pulses with center wavelengths of either 206 nm or 412 nm, are presented and discussed. Under these ionization conditions all nitrotoluenes exhibit a high degree of fragmentation which increases with the degree of substitution. For the compounds having a nitro group in position 2 and/or 6 a pronounced ortho effect leading to the loss of OH is observed. The fragmentation patterns in the lower mass range are typical for alkylated aromatic substances. While no fundamental differences between the mass spectra obtained with the two wavelengths were observed, the visible light in all cases resulted in a broader variety of fragments and additional signals in the higher mass range. The latter can be used for isomer identification.
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Affiliation(s)
- Christian Weickhardt
- Lehrstuhl Physikalische Chemie und Analytik, Brandenburgische Technische Universität Cottbus, Erich-Weinert-Strasse 1, 03044 Cottbus, Germany.
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Dotter RN, Smith CH, Young MK, Kelly PB, Jones AD, McCauley EM, Chang DP. Laser desorption/ionization time-of-flight mass spectrometry of nitrated polycyclic aromatic hydrocarbons. Anal Chem 1996; 68:2319-24. [PMID: 8686925 DOI: 10.1021/ac951132r] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Mass spectra of four nitrated polycyclic aromatic hydrocarbons (nitro-PAHs), 9-nitroanthracene, 1-nitropyrene, 2-nitro-9-fluorenone, and 2-nitrofluorene, have been investigated using single-step laser desorption/ionization time-of-flight mass spectrometry. Pulsed UV radiation at 266 or 213 nm was used for desorption and ionization of solid samples deposited on an aluminum probe. The positive molecular ion which was observed for each nitro-PAH was of greater relative intensity when 213 nm radiation was used. A strong [M - NO]+ peak was observed in all spectra, and an intense NO+ signal accompanied the [M - NO]+ signal when 213 nm was used but was only weakly present when 266 nm was used. Comparison of the various spectra suggests that nitro-PAHs undergo an excited state nitro-nitrite rearrangement, followed by loss of NO. Multiphoton ionization of the NO fragment appears to be the principal route of formation of NO+ during laser desorption/ionization when 213 nm radiation is used. The presence of the carbonyl group in 2-nitro-9-fluorenone leads to unique and prominent fragments involving losses of CO from the carbonyl bridge.
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Affiliation(s)
- R N Dotter
- Department of Chemistry, University of California, Davis 95616, USA
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A comparison of the femto-, pico- and nano-second multiphoton ionization and dissociation processes of NO2 at 248 and 496 nm. Chem Phys Lett 1995. [DOI: 10.1016/s0009-2614(95)01239-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Marshall A, Ledingham KWD, Singhal RP. Trace detection of benzene vapour in a simple ion chamber employing laser-induced resonance-enhanced multiphoton ionization in the 246–264 nm wavelength region. Analyst 1995. [DOI: 10.1039/an9952002069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Kosmidis C, Ledingham K, Clark A, Marshall A, Jennings R, Sander J, Singhal R. On the dissociation pathways of nitrobenzene. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0168-1176(94)04008-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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24
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Cassady CJ, McElvany SW. Collison-induced dissociation and photodissociation of nitroaromatic molecular ions: A unique isomerization forp-nitrotoluene andp-ethylnitrobenzene ions. ACTA ACUST UNITED AC 1993. [DOI: 10.1002/oms.1210281242] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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25
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Laser ionisation studies of nitroaromatic and NOx(x = 1 or 2) molecules in the region 224–238 nm. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0168-1176(93)80052-g] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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26
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Observation, in mass spectra and charge-inversion spectra, of the anions of some diatomic species containing B, Si or P atoms. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0168-1176(93)80100-s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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