1
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Chulanova EA, Radiush EA, Semenov NA, Hupf E, Irtegova IG, Kosenkova YS, Bagryanskaya IY, Shundrin LA, Beckmann J, Zibarev AV. Tuning Molecular Electron Affinities against Atomic Electronegativities by Spatial Expansion of a π-System. Chemphyschem 2023; 24:e202200876. [PMID: 36661050 DOI: 10.1002/cphc.202200876] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/11/2023] [Accepted: 01/19/2023] [Indexed: 01/21/2023]
Abstract
2,1,3-Benzochalcogenadiazoles C6 R4 N2 E (E/R; E=S, Se, Te; R=H, F, Cl, Br, I) and C6 H2 R2 N2 E (E/R'; E=S, Se, Te; R=Br, I) are 10π-electron hetarenes. By CV/EPR measurements, DFT calculations, and QTAIM and ELI-D analyses, it is shown that their molecular electron affinities (EAs) increase with decreasing Allen electronegativities and electron affinities of the E and non-hydrogen R (except Cl) atoms. DFT calculations for E/R+e⋅- →[E/R]⋅- electron capture reveal negative ΔG values numerically increasing with increasing atomic numbers of the E and R atoms; positive ΔS has a minor influence. It is suggested that the EA increase is caused by more effective charge/spin delocalization in the radical anions of heavier derivatives due to contributions from diffuse (a real-space expanded) p-AOs of the heavier E and R atoms; and that this counterintuitive effect might be of the general character.
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Affiliation(s)
- Elena A Chulanova
- Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation.,Current address: Institute for Applied Physics, University of Tübingen, 72076, Tübingen, Germany
| | - Ekaterina A Radiush
- Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
| | - Nikolay A Semenov
- Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
| | - Emanuel Hupf
- Institute for Inorganic Chemistry and Crystallography, University of Bremen, 28359, Bremen, Germany
| | - Irina G Irtegova
- Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
| | - Yulia S Kosenkova
- Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
| | - Irina Yu Bagryanskaya
- Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
| | - Leonid A Shundrin
- Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
| | - Jens Beckmann
- Institute for Inorganic Chemistry and Crystallography, University of Bremen, 28359, Bremen, Germany
| | - Andrey V Zibarev
- Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
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2
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Kao MH, Orr-Ewing AJ. Charge-Separated Reactive Intermediates from the UV Photodissociation of Chlorobenzene in Solution. J Phys Chem A 2022; 126:6934-6943. [PMID: 36148486 PMCID: PMC9549464 DOI: 10.1021/acs.jpca.2c05327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Although ultraviolet
(UV)-induced photochemical cleavage of carbon–halogen
bonds in gaseous halocarbons is mostly homolytic, the photolysis of
chlorobenzene in solution has been proposed to produce a phenyl cation,
c-C6H5+, which is a highly reactive
intermediate of potential use in chemical synthesis and N2 activation. Any evidence for such a route to phenyl cations is indirect,
with uncertainty remaining about the possible mechanism. Here, ultrafast
transient absorption spectroscopy of UV-excited (λ = 240 and
270 nm) chlorobenzene solutions in fluorinated (perfluorohexane) and
protic (ethanol and 2,2,2-trifluoroethanol) solvents reveals a broad
electronic absorption band centered at 540 nm that is assigned to
an isomer of chlorobenzene with both charge-separated and triplet-spin
carbene character. This spectroscopic feature is weaker, or absent,
when experiments are conducted in cyclohexane. The intermediate isomer
of chlorobenzene has a solvent-dependent lifetime of 30–110
ps, determined by reaction with the solvent or quenching to a lower-lying
singlet state. Evidence is presented for dissociation to ortho-benzyne, but the intermediate could also be a precursor to phenyl
cation formation.
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Affiliation(s)
- Min-Hsien Kao
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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3
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Valadbeigi Y, Causon T. Significance of Competitive Reactions in an Atmospheric Pressure Chemical Ionization Ion Source: Effect of Solvent. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:961-973. [PMID: 35562191 PMCID: PMC9164235 DOI: 10.1021/jasms.2c00034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 05/02/2022] [Accepted: 05/02/2022] [Indexed: 06/15/2023]
Abstract
Ionization of organic compounds with different structural and energetic properties including benzene derivatives, polycyclic aromatic hydrocarbons (PAHs), ketones, and polyenes was studied using a commercial atmospheric pressure corona discharge (APCI) ion source on a drift tube ion mobility-quadrupole-time-of-flight mass spectrometer (IM-QTOFMS). It was found that the studied cohort of compounds can be experimentally ionized via protonation, charge transfer, and hydride abstraction leading to formation of [M + H]+, [M]+•, and [M - H]+ species, respectively. By experimentally monitoring the product ions and comparing the thermodynamic data for different ionization paths, it was proposed that NO+ is one of the main reactant ions (RIs) in the ion source used. Of particular focus in this work were theoretical and experimental studies of the effect of solvents frequently used for analytical applications with this ion source (acetonitrile, methanol, and chloroform) on the ionization mechanisms. In methanol, the studied compounds were observed to be ionized mainly via proton transfer while acetonitrile suppressed the protonation of compounds and enhanced their ionization via charge transfer and hydride abstraction. Use of chloroform as a solvent led to formation of CHCl2+ as an alternative reactant ion (RI) to ionize the analytes via electrophilic substitution. Density functional theory (DFT) was used to study the different paths of ionization. The theoretical and experimental results showed that by using only the absolute thermodynamic data, the real ionization path cannot be determined and the energies of all competing processes such as charge transfer, protonation, and hydride abstraction need to be compared.
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4
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Dobrowolski JC, Dudek WM, Karpińska G, Baraniak A. Substituent Effect in the Cation Radicals of Monosubstituted Benzenes. Int J Mol Sci 2021; 22:6936. [PMID: 34203254 PMCID: PMC8269098 DOI: 10.3390/ijms22136936] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/19/2021] [Accepted: 06/22/2021] [Indexed: 01/30/2023] Open
Abstract
In 30 monosubstituted benzene cation radicals, studied at the ωB97XD/aug-cc-pVTZ level, the phenyl rings usually adopt a compressed form, but a differently compressed form-equivalent to an elongated one-may coexist. The computational and literature ionization potentials are well correlated. The geometrical and magnetic aromaticity, estimated using HOMA and NICS indices, show the systems to be structurally aromatic but magnetically antiaromatic or only weakly aromatic. The partial charge is split between the substituent and ring and varies the most at C(ipso). In the ring, the spin is 70%, concentrated equally at the C(ipso) and C(p) atoms. The sEDA(D) and pEDA(D) descriptors of the substituent effect in cation radicals, respectively, were determined. In cation radicals, the substituent effect on the σ-electron system is like that in the ground state. The effect on the π-electron systems is long-range, and its propagation in the radical quinone-like ring is unlike that in the neutral molecules. The pEDA(D) descriptor correlates well with the partial spin at C(ipso) and C(p) and weakly with the HOMA(D) index. The correlation of the spin at the ring π-electron system and the pEDA(D) descriptor shows that the electron charge supplied to the ring π-electron system and the spin flow oppositely.
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Affiliation(s)
- Jan Cz. Dobrowolski
- National Medicines Institute, 00-725 Warsaw, Poland; (G.K.); (A.B.)
- Institute of Nuclear Chemistry and Technology, 03-195 Warsaw, Poland;
| | - Wojciech M. Dudek
- Institute of Nuclear Chemistry and Technology, 03-195 Warsaw, Poland;
| | | | - Anna Baraniak
- National Medicines Institute, 00-725 Warsaw, Poland; (G.K.); (A.B.)
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5
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Zhao L, Lu W, Ahmed M, Zagidullin MV, Azyazov VN, Morozov AN, Mebel AM, Kaiser RI. Gas-phase synthesis of benzene via the propargyl radical self-reaction. SCIENCE ADVANCES 2021; 7:7/21/eabf0360. [PMID: 34020951 PMCID: PMC8139581 DOI: 10.1126/sciadv.abf0360] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 03/31/2021] [Indexed: 06/01/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) have been invoked in fundamental molecular mass growth processes in our galaxy. We provide compelling evidence of the formation of the very first ringed aromatic and building block of PAHs-benzene-via the self-recombination of two resonantly stabilized propargyl (C3H3) radicals in dilute environments using isomer-selective synchrotron-based mass spectrometry coupled to theoretical calculations. Along with benzene, three other structural isomers (1,5-hexadiyne, fulvene, and 2-ethynyl-1,3-butadiene) and o-benzyne are detected, and their branching ratios are quantified experimentally and verified with the aid of computational fluid dynamics and kinetic simulations. These results uncover molecular growth pathways not only in interstellar, circumstellar, and solar systems environments but also in combustion systems, which help us gain a better understanding of the hydrocarbon chemistry of our universe.
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Affiliation(s)
- Long Zhao
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | | | - Valeriy N Azyazov
- Lebedev Physical Institute, Samara 443011, Russian Federation
- Samara National Research University, Samara 443086, Russian Federation
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
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6
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Prajapati D, Yadav H, Vinodkumar M, Limbachiya C, Vinodkumar PC. Electron impact scattering study on chlorobenzene. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1554191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Dineshkumar Prajapati
- Shree M R Arts & Science College, Rajpipla, India
- Department of Physics, Sardar Patel University, Vallabh Vidyanagar, India
| | - Hitesh Yadav
- Department of Physics, Sardar Patel University, Vallabh Vidyanagar, India
- V. P. & R. P. T. P. Science College, Vallabh Vidyanagar, India
| | | | - Chetan Limbachiya
- Department of Applied Physics, The M. S. University of Baroda, Vadodara, India
| | - P. C. Vinodkumar
- Department of Physics, Sardar Patel University, Vallabh Vidyanagar, India
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7
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Romańczyk PP, Kurek SS. The Reduction Potential of Diphenyliodonium Polymerisation Photoinitiator Is Not −0.2 V vs. SCE. A Computational Study. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.09.166] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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8
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Palmer MH, Ridley T, Vrønning Hoffmann S, Jones NC, Coreno M, de Simone M, Grazioli C, Zhang T, Biczysko M, Baiardi A, Peterson KA. Combined theoretical and experimental study of the valence, Rydberg, and ionic states of chlorobenzene. J Chem Phys 2016; 144:124302. [PMID: 27036443 DOI: 10.1063/1.4944078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
New photoelectron (PE) and ultra violet (UV) and vacuum UV (VUV) spectra have been obtained for chlorobenzene by synchrotron study with higher sensitivity and resolution than previous work and are subjected to detailed analysis. In addition, we report on the mass-resolved (2 + 1) resonance enhanced multiphoton ionization (REMPI) spectra of a jet-cooled sample. Both the VUV and REMPI spectra have enabled identification of a considerable number of Rydberg states for the first time. The use of ab initio calculations, which include both multi-reference multi-root doubles and singles configuration interaction (MRD-CI) and time dependent density functional theoretical (TDDFT) methods, has led to major advances in interpretation of the vibrational structure of the ionic and electronically excited states. Franck-Condon (FC) analyses of the PE spectra, including both hot and cold bands, indicate much more complex envelopes than previously thought. The sequence of ionic states can be best interpreted by our multi-configuration self-consistent field computations and also by comparison of the calculated vibrational structure of the B and C ionic states with experiment; these conclusions suggest that the leading sequence is the same as that of iodobenzene and bromobenzene, namely: X(2)B1(3b1 (-1)) < A(2)A2(1a2 (-1)) < B(2)B2(6b2 (-1)) < C(2)B1(2b1 (-1)). The absorption onset near 4.6 eV has been investigated using MRD-CI and TDDFT calculations; the principal component of this band is (1)B2 and an interpretation based on the superposition of FC and Herzberg-Teller contributions has been performed. The other low-lying absorption band near 5.8 eV is dominated by a (1)A1 state, but an underlying weak (1)B1 state (πσ(∗)) is also found. The strongest band in the VUV spectrum near 6.7 eV is poorly resolved and is analyzed in terms of two ππ(∗) states of (1)A1 (higher oscillator strength) and (1)B2 (lower oscillator strength) symmetries, respectively. The calculated vertical excitation energies of these two states are critically dependent upon the presence of Rydberg functions in the basis set, since both manifolds are strongly perturbed by the Rydberg states in this energy range. A number of equilibrium structures of the ionic and singlet excited states show that the molecular structure is less subject to variation than corresponding studies for iodobenzene and bromobenzene.
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Affiliation(s)
- Michael H Palmer
- School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, Scotland
| | - Trevor Ridley
- School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, Scotland
| | - Søren Vrønning Hoffmann
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Nykola C Jones
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Marcello Coreno
- CNR-ISM, Basovizza Area Science Park, 1-34149 Trieste, Italy
| | | | | | - Teng Zhang
- Department of Physics and Astronomy, University of Uppsala, Uppsala, Sweden
| | - Malgorzata Biczysko
- International Centre for Quantum and Molecular Structures, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China
| | - Alberto Baiardi
- Scuola Normale Superiore, Piazza Cavalieri 7, 56126 Pisa, Italy
| | - Kirk A Peterson
- Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, USA
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9
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Kauppila TJ, Haack A, Kroll K, Kersten H, Benter T. Nucleophilic Aromatic Substitution Between Halogenated Benzene Dopants and Nucleophiles in Atmospheric Pressure Photoionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:422-431. [PMID: 26637323 DOI: 10.1007/s13361-015-1315-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 11/12/2015] [Accepted: 11/24/2015] [Indexed: 06/05/2023]
Abstract
In a preceding work with dopant assisted-atmospheric pressure photoionization (DA-APPI), an abundant ion at [M + 77](+) was observed in the spectra of pyridine and quinoline with chlorobenzene dopant. This contribution aims to reveal the identity and route of formation of this species, and to systematically investigate structurally related analytes and dopants. Compounds containing N-, O-, and S-lone pairs were investigated with APPI in the presence of fluoro-, chloro-, bromo-, and iodobenzene dopants. Computational calculations on a density functional theory (DFT) level were carried out to study the reaction mechanism for pyridine and the different halobenzenes. The experimental and computational results indicated that the [M + 77](+) ion was formed by nucleophilic aromatic ipso-substitution between the halobenzene radical cation and nucleophilic analytes. The reaction was most efficient for N-heteroaromatic compounds, and it was weakened by sterical effects and enhanced by resonance stabilization. The reaction was most efficient with chloro-, bromo-, and iodobenzenes, whereas with fluorobenzene the reaction was scarcely observed. The calculated Gibbs free energies for the reaction between pyridine and the halobenzenes were shown to increase in the order I < Br < Cl < F. The reaction was found endergonic for fluorobenzene due to the strong C-F bonding, and exergonic for the other halobenzenes. For fluoro- and chlorobenzenes the reaction was shown to proceed through an intermediate state corresponding to [M + dopant](+), which was highly stable for fluorobenzene. For the bulkier bromine and iodine, this intermediate did not exist, but the halogens were shown to detach already during the approach by the nucleophile.
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Affiliation(s)
- Tiina J Kauppila
- Faculty of Pharmacy, University of Helsinki, Helsinki, 00014, Finland.
| | - Alexander Haack
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Wuppertal, 42119, Germany
| | - Kai Kroll
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Wuppertal, 42119, Germany
| | - Hendrik Kersten
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Wuppertal, 42119, Germany
| | - Thorsten Benter
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Wuppertal, 42119, Germany
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Davey NG, Bell RJ, Krogh ET, Gill CG. A membrane introduction mass spectrometer utilizing ion-molecule reactions for the on-line speciation and quantitation of volatile organic molecules. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:2187-2194. [PMID: 26522309 DOI: 10.1002/rcm.7380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 08/28/2015] [Accepted: 08/29/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE The ability of membrane introduction mass spectrometry to quantitatively resolve low molecular weight volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene and xylene (BTEX) using electron ionization (EI) can be compromised by isobaric interferences. This work focuses on reducing isobaric interferences with ion-molecule reactions in a portable quadrupole ion trap mass spectrometer for the analysis of VOCs. METHODS EI was used to produce reagent ions from precursors (chloroform, methyl iodide, trichloroethylene or chlorobenzene) that were continually infused into the helium acceptor phase upstream of the membrane introduction mass spectrometry (MIMS) sampling interface. The reagent ions were selectively stored in the ion trap, and then allowed to react with target VOC analytes in air samples via ion-molecule reactions within the trap storage volume. A variety of reaction times were examined (50-5000 ms), and the resulting product ions were analyzed in positive ion mode. RESULTS The detection limits achieved were comparable with those obtained using EI (low ppbv), and in some cases better than for EI coupled with tandem mass spectrometry (MS/MS). For the VOCs studied, isobaric interferences were greatly reduced or eliminated using chloroform as a reagent gas. The predominant ionization mechanism was via adduct formation, although charge transfer and hydride abstractions were also observed. An internal standard was shown to be effective at correcting for signal changes due to consumption of reagent ions when complex mixtures were sampled. CONCLUSIONS Ion-molecule reactions were exploited to eliminate isobaric interferences that are often encountered in direct, real-time analysis strategies for atmospheric VOC mixtures. The use of a continuously infused internal standard will improve quantitative results in field applications where analyte concentration and sample complexity may be wide ranging.
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Affiliation(s)
- Nicholas G Davey
- Chemistry Department, University of Victoria, Victoria, BC, Canada
- Applied Environmental Research Laboratories (AERL), Chemistry Department, Vancouver Island University, Nanaimo, BC, Canada
| | - Ryan J Bell
- Applied Environmental Research Laboratories (AERL), Chemistry Department, Vancouver Island University, Nanaimo, BC, Canada
| | - Erik T Krogh
- Chemistry Department, University of Victoria, Victoria, BC, Canada
- Applied Environmental Research Laboratories (AERL), Chemistry Department, Vancouver Island University, Nanaimo, BC, Canada
| | - Chris G Gill
- Chemistry Department, University of Victoria, Victoria, BC, Canada
- Applied Environmental Research Laboratories (AERL), Chemistry Department, Vancouver Island University, Nanaimo, BC, Canada
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11
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Ribeiro da Silva MAV, Monte MJS, Rocha IM, Cimas Á. Energetic Study Applied to the Knowledge of the Structural and Electronic Properties of Monofluorobenzonitriles. J Org Chem 2012; 77:4312-22. [DOI: 10.1021/jo3002968] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Manuel A. V. Ribeiro da Silva
- Centro de
Investigação em Química, Department of Chemistry
and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007, Portugal
| | - Manuel J. S. Monte
- Centro de
Investigação em Química, Department of Chemistry
and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007, Portugal
| | - Inês M. Rocha
- Centro de
Investigação em Química, Department of Chemistry
and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007, Portugal
| | - Álvaro Cimas
- Centro de
Investigação em Química, Department of Chemistry
and Biochemistry, Faculty of Science, University of Porto, Rua do Campo Alegre, 687, P-4169-007, Portugal
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12
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A quantum mechanical study of bioactive 3-chloro-2,5-dihydroxybenzyl alcohol through substitutions. Theor Chem Acc 2011. [DOI: 10.1007/s00214-011-1040-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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13
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Stevens WR, Ruscic B, Baer T. Heats of Formation of C6H5•, C6H5+, and C6H5NO by Threshold Photoelectron Photoion Coincidence and Active Thermochemical Tables Analysis. J Phys Chem A 2010; 114:13134-45. [DOI: 10.1021/jp107561s] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- William R. Stevens
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27517, United States, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States, and Computation Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Branko Ruscic
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27517, United States, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States, and Computation Institute, University of Chicago, Chicago, Illinois 60637, United States
| | - Tomas Baer
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27517, United States, Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States, and Computation Institute, University of Chicago, Chicago, Illinois 60637, United States
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14
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Intermolecular interactions and structural dichotomy in 1,3,2,4-benzodithiadiazine crystals. J STRUCT CHEM+ 2009. [DOI: 10.1007/s10947-009-0017-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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15
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Experimental and quantum chemical investigation on fluorocarbonylsulfenyl benzoate, FC(O)SOC(O)C6H5. J Mol Struct 2009. [DOI: 10.1016/j.molstruc.2009.01.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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16
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Ge M, Yao L. Substituent effect on electronic structures of halonitrobenzenes. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 71:1499-1502. [PMID: 18573688 DOI: 10.1016/j.saa.2008.05.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Accepted: 05/12/2008] [Indexed: 05/26/2023]
Abstract
The electronic structures and substituent effects of o-, m-, and p-chloronitrobenzene and bromonitrobenzene have been studied by ultraviolet photoelectron spectroscopy (UPS). It was found that the o-isomer possesses particular electronic properties. This characteristic depends on the conjugation between the benzene ring pi orbital and the nitro group pi orbital and the interaction of the halogen and nitro groups in the adjacent position.
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Affiliation(s)
- Maofa Ge
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, PR China.
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17
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Yao L, Du L, Ge M, Ma C, Wang D. Experimental and theoretical study of substituent effects of iodonitrobenzenes. J Phys Chem A 2007; 111:10105-10. [PMID: 17880050 DOI: 10.1021/jp073605r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The electronic structures and substituent effects of o-, m-, and p-iodonitrobenzene have been studied by ultraviolet photoelectron spectroscopy (UPS). The observed bands were interpreted on the basis of empirical arguments and theoretical calculations. The analysis of electronic effects of the donor/acceptor substituent groups is essential for the reliable assignment of the observed photoelectron spectra. The investigation of pi- and n-orbital ionization potentials enabled us to describe the correlation between substituent effects and the relative reactivities of the iodonitrobenzenes. It was found that the energy order of the pi(2) and n(II) parallel orbitals is reversed as a result of the combined influence of the electron-withdrawing nitro group and the electron-donating iodine atom. Distinct changes of the pi and n bands occur in o-iodonitrobenzene. This characteristic depends on the conjugation between the pi orbitals of the benzene ring and the nitro group and the interaction of in-plane lone pairs of iodine and one of the oxygen atoms of the nitro group in the adjacent position. This might contribute to the high reactivity of o-iodonitrobenzene in a number of reactions.
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Affiliation(s)
- Li Yao
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100080, PR China
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Kuribayashi S, Yamakoshi H, Danno M, Sakai S, Tsuruga S, Futami H, Morii S. VUV single-photon ionization ion trap time-of-flight mass spectrometer for on-line, real-time monitoring of chlorinated organic compounds in waste incineration flue gas. Anal Chem 2007; 77:1007-12. [PMID: 15858979 DOI: 10.1021/ac048761y] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, a sensitive and robust vacuum ultra-violet (VUV) single-photon ionization (SPI) ion trap time-of-flight mass spectrometer (VUV-SPI-IT-TOFMS) for on-line, realtime monitoring of chlorinated organic compounds in waste incineration flue gas has been newly developed. The fragment-free SPI technique with 121.6-nm VUV lamp irradiated by a microwave generator and the quadrupole ion trap to accumulate and select analyte ions were combined with a reflectron time-of-flight mass spectrometer to detect chlorinated organic compounds at trace level. This measuring system was tuned up to detect dioxins precursors with the aim at an application to monitoring trace level toxic substances in flue gases from incinerator furnaces. As a result, this technology has made it possible to analyze trichlorobenzene (T3CB), a dioxin precursor, in 18 s with a sensitivity of 80 ng/m3-N (10 pptv) using the selective accumulation of analyte substances and separation of interfering substances in the ion trap. Moreover, the first field test of the continuous monitoring T3CB in an actual waste incineration flue gas had been done for 7 months. The results show that this system has an exceeding robust performance and is able to maintain the high sensitivity in analyzing T3CB for long months of operation.
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Affiliation(s)
- Shizuma Kuribayashi
- Advanced Technology Research Center, Yokohama Research & Development Center, Mitsubishi Heavy Industries, Ltd, 1-8-1 Sachiura, Kanazawa-ku, Yokohama, Japan.
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Lee SH, Wu CY, Yang SK, Lee YP. Photodissociation dynamics of fluorobenzene (C6H5F) at 157 and 193 nm: Branching ratios and distributions of kinetic energy. J Chem Phys 2006; 125:144301. [PMID: 17042584 DOI: 10.1063/1.2353118] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Following photodissociation of fluorobenzene (C6H5F) at 193 and 157 nm, we detected the products with fragmentation-translational spectroscopy by utilizing a tunable vacuum ultraviolet beam from a synchrotron for ionization. Between two primary dissociation channels observed upon irradiation at 193 (157) nm, the HF-elimination channel C6H5F --> HF + C6H4 dominates, with a branching ratio of 0.94+/-0.02 (0.61+/-0.05) and an average release of kinetic energy of 103 (108) kJ mol(-1); the H-elimination channel C6H5F --> H + C6H4F has a branching ratio of 0.06+/-0.02 (0.39+/-0.05) and an average release of kinetic energy of 18.6 (26.8) kJ mol(-1). Photofragments H, HF, C6H4, and C6H4F produced via the one-photon process have nearly isotropic angular distributions. Both the HF-elimination and the H-elimination channels likely proceed via the ground-state electronic surface following internal conversion of C6H5F; these channels exhibit small fractions of kinetic energy release from the available energy, indicating that the molecular fragments are highly internally excited. We also determined the ionization energy of C6H4F to be 8.6+/-0.2 eV.
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Affiliation(s)
- Shih-Huang Lee
- National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan.
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Hunger R, Jaegermann W, Merson A, Shapira Y, Pettenkofer C, Rappich J. Electronic Structure of Methoxy-, Bromo-, and Nitrobenzene Grafted onto Si(111). J Phys Chem B 2006; 110:15432-41. [PMID: 16884265 DOI: 10.1021/jp055702v] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The properties of Si(111) surfaces grafted with benzene derivatives were investigated using ultraviolet photoemission spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). The investigated materials were nitro-, bromo-, and methoxybenzene layers (-C(6)H(4)-X, with X = NO(2), Br, O-CH(3)) deposited from diazonium salt solutions in a potentiostatic electrochemical process. The UPS spectra of the valence band region are governed by the molecular orbital density of states of the adsorbates, which is modified from the isolated state in the gas phase due to molecule-molecule and molecule-substrate interaction. Depending on the adsorbate, clearly different emission features are observed. The analysis of XPS intensities clearly proves multilayer formation for bromo- and nitrobenzene in agreement with the amount of charge transferred during the grafting process. Methoxybenzene forms only a sub-monolayer coverage. The detailed analysis of binding energy shifts of the XPS emissions for determining the band bending and the secondary electron onset in UPS spectra for determining the work function allow one to discriminate between surface dipole layers--changing the electron affinity--and band bending, affecting only the work function. Thus, complete energy band diagrams of the grafted Si(111) surfaces can be constructed. It was found that silicon surface engineering can be accomplished by the electrochemical grafting process using nitrobenzene and bromobenzene: silicon-derived interface gap states are chemically passivated, and the adsorbate-related surface dipole effects an increase of the electron affinity.
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Affiliation(s)
- Ralf Hunger
- Institute of Materials Science, Technische Universität Darmstadt, Petersenstr. 23, 64287 Darmstadt, Germany.
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Liu T, Callis PR, Hesp BH, de Groot M, Buma WJ, Broos J. Ionization potentials of fluoroindoles and the origin of nonexponential tryptophan fluorescence decay in proteins. J Am Chem Soc 2005; 127:4104-13. [PMID: 15771548 DOI: 10.1021/ja043154d] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This work reports an explanation for the unusual monoexponential fluorescence decay of 5-fluorotryptophan (5FTrp) in single-Trp mutant proteins [Broos, J.; Maddalena, F.; Hesp, B. H. J. Am. Chem. Soc. 2004, 126, 22-23] and substantially clarifies the origin of the ubiquitous nonexponential fluorescence decay of tryptophan in proteins. Our results strongly suggest that the extent of nonexponential fluorescence decay is governed primarily by the efficiency of electron transfer (ET) quenching by a nearby amide group in the peptide bond. Fluoro substitution increases the ionization potential (IP) of indole, thereby suppressing the ET rate, leading to a longer average lifetime and therefore a more homogeneous decay. We report experimental IPs for a number of substituted indoles including 5-fluoroindole, 5-fluoro-3-methylindole, and 6-fluoroindole, along with accurate ab initio calculations of the IPs for these and 20 related molecules. The results predict the IP of 5-fluorotryptophan to be 0.19 eV higher than that of tryptophan. 5-Fluoro substitution does not measurably alter the excitation-induced change in permanent dipole moment nor does it change the fluorescent state from 1La to 1Lb. In combination with electronic structure information this argues that the increased IP and the decreased excitation energy of the 1La state, together 0.3 eV, are solely responsible for the strong reduction of electron transfer quenching. 6-Fluoro substitution is predicted to increase the IP by a mere 0.09 eV. In agreement with our conclusions, the fluorescence decay curves of 6-fluorotryptophan-containing proteins are well fit using only two decay times compared to three required for Trp.
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Affiliation(s)
- Tiqing Liu
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
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Ohno K. Exterior Characteristics of Molecular Orbitals and Molecular Surfaces as Studied by Atomic Probes. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2004. [DOI: 10.1246/bcsj.77.887] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Affiliation(s)
- Edward Todd Urbansky
- United States Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Water Supply and Water Resources Division, Cincinnati, Ohio 45268, USA.
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Imura K, Kishimoto N, Ohno K. Collision-Energy-Resolved Penning Ionization Electron Spectroscopy of Difluorobenzenes: Anisotropic Interaction of Difluorobenzenes with He*(23S) and Assignments of Ionic States. J Phys Chem A 2001. [DOI: 10.1021/jp010477c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Kohei Imura
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Naoki Kishimoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Koichi Ohno
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan
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Imura K, Kishimoto N, Ohno K. Two-Dimensional Penning Ionization Electron Spectroscopy of Monohalogenobenzenes by He*(23S): C6H5X (X = F, Cl, Br, I). J Phys Chem A 2001. [DOI: 10.1021/jp004430n] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Kohei Imura
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Naoki Kishimoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Koichi Ohno
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan
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Electronic structure of phenyl-N,N-dimorpholinomethanes. J STRUCT CHEM+ 2000. [DOI: 10.1007/bf02683924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Anand R, Hofstein JD, LeClaire JE, Johnson PM, Cossart-Magos C. Assignment of the B̃+ State of the Chlorobenzene Cation Using Photoinduced Rydberg Ionization (PIRI) Spectroscopy. J Phys Chem A 1999. [DOI: 10.1021/jp992263p] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- R. Anand
- Department of Chemistry, The State University of New York at Stony Brook, Stony Brook, New York 11794-3400
| | - J. D. Hofstein
- Department of Chemistry, The State University of New York at Stony Brook, Stony Brook, New York 11794-3400
| | - J. E. LeClaire
- Department of Chemistry, The State University of New York at Stony Brook, Stony Brook, New York 11794-3400
| | - P. M. Johnson
- Department of Chemistry, The State University of New York at Stony Brook, Stony Brook, New York 11794-3400
| | - C. Cossart-Magos
- Laboratoire de Photophysique Moléculaire du CNRS, Institut de Physico-Chimie Moléculaire, Bâtiment 213, Université de Paris-Sud, F-91405 Orsay Cedex, France
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Anand R, LeClaire JE, Johnson PM. Photoinduced Rydberg Ionization (PIRI) Spectroscopy of the B̃ State of the Fluorobenzene Cation. J Phys Chem A 1999. [DOI: 10.1021/jp984697a] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Richa Anand
- Department of Chemistry, The State University of New York at Stony Brook, Stony Brook, New York 11794-3400
| | - Jeffrey E. LeClaire
- Department of Chemistry, The State University of New York at Stony Brook, Stony Brook, New York 11794-3400
| | - Philip M. Johnson
- Department of Chemistry, The State University of New York at Stony Brook, Stony Brook, New York 11794-3400
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Skaggs RL, Aguín ML, Lewis WM, Birks JW. Detection of Argon by Penning Ionization and Competitive Absorption Using a Sensitized Photoionization Detector. Anal Chem 1998. [DOI: 10.1021/ac9802022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rhonda L. Skaggs
- Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado 80309-0216
| | - Marta Lores Aguín
- Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado 80309-0216
| | - William M. Lewis
- Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado 80309-0216
| | - John W. Birks
- Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado 80309-0216
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LeClaire JE, Anand R, Johnson PM. Photoinduced Rydberg ionization spectroscopy of phenol: The structure and assignment of the B̃-state of the cation. J Chem Phys 1997. [DOI: 10.1063/1.473677] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Oomori T, Hikida T. Absorption and emission spectra of C6F5X+ (X = H, F, Cl, Br, and I) radical cation in perfluorohexane matrix. Chem Phys 1993. [DOI: 10.1016/0301-0104(93)85085-m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Theoretical study of mechanisms of aromatic nucleophilic substitution in the gas phase. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0166-1280(93)87187-i] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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