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Meißner R, Feketeová L, Bayer A, Limão-Vieira P, Denifl S. Formation of negative and positive ions in the radiosensitizer nimorazole upon low-energy electron collisions. J Chem Phys 2021; 154:074306. [PMID: 33607883 DOI: 10.1063/5.0040045] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A comprehensive investigation of low-energy electron attachment and electron ionization of the nimorazole radiosensitizer used in cancer radiation therapy is reported by means of a gas-phase crossed beam experiment in an electron energy range from 0 eV to 70 eV. Regarding negative ion formation, we discuss the formation of fifteen fragment anions in the electron energy range of 0 eV-10 eV, where the most intense signal is assigned to the nitrogen dioxide anion NO2 -. The other fragment anions have been assigned to form predominantly from a common temporary negative ion state close to 3 eV of the nitroimidazole moiety, while the morpholine moiety seems to act only as a spectator in the dissociative electron attachment event to nimorazole. Quantum chemical calculations have been performed to help interpreting the experimental data with thermochemical thresholds, electron affinities, and geometries of some of the neutral molecules. As far as positive ion formation is concerned, the mass spectrum at the electron energy of 70 eV shows a weakly abundant parent ion and C5H10NO+ as the most abundant fragment cation. We report appearance energy (AE) measurements for six cations. For the intact nimorazole molecular cation, the AE of 8.16 ± 0.05 eV was obtained, which is near the presently calculated adiabatic ionization energy.
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Affiliation(s)
- R Meißner
- Institute for Ion Physics and Applied Physics and Center for Biomolecular Sciences (CMBI), University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - L Feketeová
- Institute for Ion Physics and Applied Physics and Center for Biomolecular Sciences (CMBI), University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - A Bayer
- Institute for Ion Physics and Applied Physics and Center for Biomolecular Sciences (CMBI), University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - P Limão-Vieira
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - S Denifl
- Institute for Ion Physics and Applied Physics and Center for Biomolecular Sciences (CMBI), University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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2
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Grande S, Tampieri F, Nikiforov A, Giardina A, Barbon A, Cools P, Morent R, Paradisi C, Marotta E, De Geyter N. Radicals and Ions Formed in Plasma-Treated Organic Solvents: A Mechanistic Investigation to Rationalize the Enhancement of Electrospinnability of Polycaprolactone. Front Chem 2019; 7:344. [PMID: 31165059 PMCID: PMC6535498 DOI: 10.3389/fchem.2019.00344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 04/26/2019] [Indexed: 01/23/2023] Open
Abstract
This paper reports and discusses the beneficial effects on the quality of electrospun polycaprolactone nanofibers brought about by pretreatment of the solvent with non-thermal plasma. Chloroform/dimethylformamide 9:1 (CHCl3:DMF 9:1) and pure chloroform were pretreated by a few minute exposure to the plasma generated by an atmospheric pressure plasma jet (APPJ). Interestingly, when pure chloroform was used, the advantages of plasma pretreatment of the solvent were way less pronounced than found with the CHCl3:DMF 9:1 mixture. The chemical modifications induced by the plasma in the solvents were investigated by means of complementary analytical techniques. GC-MS revealed the formation of solvent-derived volatile products, notably tetrachloroethylene (C2Cl4), 1,1,2,2-tetrachloroethane (C2H2Cl4), pentachloroethane (C2HCl5), hexachloroethane (C2Cl6) and, in the case of the mixed solvent, also N-methylformamide (C2H5NO). The chlorinated volatile products are attributed to reactions of ·Cl and Cl-containing methyl radicals and carbenes formed in the plasma-treated solvents. ·Cl and ·CCl3 radicals were detected and identified by EPR spectroscopy analyses. Ion chromatography revealed the presence of Cl-, NO 3 - , and HCOO- (the latter only in the presence of DMF) in the plasma-treated solvents, thus accounting for the observed increased conductivity and acidification of the solvent after plasma treatment. Mechanisms for the formation of these solvent derived products induced by plasma are proposed and discussed. The major role of radicals and ions in the plasma chemistry of chloroform and of the chloroform/dimethylformamide mixture is highlighted. The results provide insight into the interaction of plasma with organic solvents, a field so far little explored but holding promise for interesting applications.
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Affiliation(s)
- Silvia Grande
- Research Unit Plasma Technology, Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Francesco Tampieri
- Department of Chemical Sciences, Università degli Studi di Padova, Padua, Italy
| | - Anton Nikiforov
- Research Unit Plasma Technology, Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Agata Giardina
- Department of Chemical Sciences, Università degli Studi di Padova, Padua, Italy
| | - Antonio Barbon
- Department of Chemical Sciences, Università degli Studi di Padova, Padua, Italy
| | - Pieter Cools
- Research Unit Plasma Technology, Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Rino Morent
- Research Unit Plasma Technology, Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
| | - Cristina Paradisi
- Department of Chemical Sciences, Università degli Studi di Padova, Padua, Italy
| | - Ester Marotta
- Department of Chemical Sciences, Università degli Studi di Padova, Padua, Italy
| | - Nathalie De Geyter
- Research Unit Plasma Technology, Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium
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3
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Han HY, Feng HT, Li H, Wang HM, Jiang HH, Chu YN. Electron Attachment Studies for CHCl3 Using Ion Mobility Spectrometry. CHINESE J CHEM PHYS 2011. [DOI: 10.1088/1674-0068/24/02/218-224] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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4
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Edtbauer A, Sulzer P, Mauracher A, Mitterdorfer C, Ferreira da Silva F, Denifl S, Märk TD, Probst M, Nunes Y, Limão-Vieira P, Scheier P. Dissociative electron attachment to pentaerythritol tetranitrate: Significant fragmentation near 0 eV. J Chem Phys 2010; 132:134305. [DOI: 10.1063/1.3386386] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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5
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Cannon M, Wang CH, Liu Y, Dunning FB, Steill JD. Temperature dependence of reactions involving electron transfer in K(np)/C2Cl4 collisions. J Chem Phys 2009; 130:244311. [PMID: 19566157 DOI: 10.1063/1.3158604] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Electron transfer in K(np)-C(2)Cl(4) collisions, which leads to formation of both Cl(-) and C(2)Cl(4)(-) anions, is investigated as a function of target temperature over the range of 300-650 K. Measurements at high n (n approximately 30) show that the likelihood of Cl(-) production increases rapidly with temperature indicating the presence of a dissociation barrier. The data yield an activation energy of approximately 0.1 eV. A broad distribution of product C(2)Cl(4)(-) lifetimes is observed that extends from microseconds to milliseconds, this distribution moving toward shorter lifetimes as the target temperature is increased. The measured lifetimes are consistent with the predictions of quasiequilibrium theory. Studies at low n (n approximately 14) show a substantial fraction of the product K(+)-Cl(-) and K(+)-C(2)Cl(4)(-) ion pairs is electrostatically bound leading to creation of heavy-Rydberg ion-pair states. Variations in target temperature lead to changes in kinetic energy of relative motion of the reactants that can result in marked changes in the fraction of ion pairs that is bound, especially at low Rydberg atom velocities. In the case of bound K(+)-C(2)Cl(4)(-) ion pairs a few percent subsequently dissociate by the conversion of internal energy in the anion into translational energy of the ion pair. Analysis of the data points to a mean energy conversion of approximately 60-90 meV, much less than the available excess energy of reaction, approximately 0.7 eV.
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Affiliation(s)
- M Cannon
- Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77005, USA.
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6
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Fabrikant II, Hotop H. On the validity of the Arrhenius equation for electron attachment rate coefficients. J Chem Phys 2008; 128:124308. [DOI: 10.1063/1.2841079] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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7
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Burrow PD, Gallup GA, Scheer AM, Denifl S, Ptasinska S, Märk T, Scheier P. Vibrational Feshbach resonances in uracil and thymine. J Chem Phys 2007; 124:124310. [PMID: 16599677 DOI: 10.1063/1.2181570] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Sharp peaks in the dissociative electron attachment (DEA) cross sections of uracil and thymine at energies below 3 eV are assigned to vibrational Feshbach resonances (VFRs) arising from coupling between the dipole bound state and the temporary anion state associated with occupation of the lowest sigma* orbital. Three distinct vibrational modes are identified, and their presence as VFRs is consistent with the amplitudes and bonding characteristics of the sigma* orbital wave function. A deconvolution method is also employed to yield higher effective energy resolution in the DEA spectra. The site dependence of DEA cross sections is evaluated using methyl substituted uracil and thymine to block H atom loss selectively. Implications for the broader issue of DNA damage are briefly discussed.
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Affiliation(s)
- P D Burrow
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0111, USA.
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Denifl S, Ptasińska S, Sonnweber B, Scheier P, Liu D, Hagelberg F, Mack J, Scott LT, Märk TD. Free-electron attachment to coronene and corannulene in the gas phase. J Chem Phys 2007; 123:104308. [PMID: 16178598 DOI: 10.1063/1.2008947] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Electron attachment to the polyaromatic hydrocarbons coronene and corannulene is studied in the electron energy range of about 0-14 eV using a high-resolution crossed electron-neutral beam setup. The major anions observed are the parent anions peaking at about 0 eV with cross sections of 3.8 x 10(-20) and 1 x 10(-19) m(2), respectively. The only fragment anions formed in coronene and corannulene are the dehydrogenated coronene and corannulene anions. Other anions observed in the negative mass spectra at about 0 eV can be ascribed to impurities of the sample. High-level quantum-mechanical studies are carried out for the determination of electron affinities, hydrogen binding energies, and structures of both molecules. The behavior of coronene and corannulene upon electron attachment is compared with that of other polyaromatic hydrocarbons studied previously.
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Affiliation(s)
- S Denifl
- Institut für Ionenphysik, Leopold Franzens Universität, Innsbruck, Austria.
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9
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Ptasińska S, Denifl S, Mróz B, Probst M, Grill V, Illenberger E, Scheier P, Märk TD. Bond selective dissociative electron attachment to thymine. J Chem Phys 2007; 123:124302. [PMID: 16392477 DOI: 10.1063/1.2035592] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Free-electron attachment to thymine and partially deuterated thymine, where D replaces H at all carbon atoms, is studied in the electron energy range from about 0 to 15 eV. The formation of fragment anions that are formed by the loss of one or two H (D) atoms is analyzed as a function of the incident electron energy using a crossed electron/neutral beam apparatus in combination with a quadrupole mass spectrometer. By using partially deuterated thymine and quantum-chemical calculation a bond selectivity for the loss of one and two hydrogen atoms is observed that is determined only by the kinetic energy of the incident electron.
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Affiliation(s)
- S Ptasińska
- Institut für Ionenphysik, The Center of Molecular Bioscience Innsbruck, Leopold Franzens Universität, Technikerstrasse 25, A-6020 Innsbruck, Austria.
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10
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Ptasińska S, Denifl S, Gohlke S, Scheier P, Illenberger E, Märk TD. Decomposition of thymidine by low-energy electrons: implications for the molecular mechanisms of single-strand breaks in DNA. Angew Chem Int Ed Engl 2007; 45:1893-6. [PMID: 16506258 DOI: 10.1002/anie.200503930] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Sylwia Ptasińska
- Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck und Center for Molecular Biosciences Innsbruck (CMBI), Austria
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11
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Ptasińska S, Denifl S, Scheier P, Märk TD. Inelastic electron interaction (attachment/ionization) with deoxyribose. J Chem Phys 2006; 120:8505-11. [PMID: 15267776 DOI: 10.1063/1.1690231] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have investigated experimentally the formation of anions and cations of deoxyribose sugar (C(5)H(10)O(4)) via inelastic electron interaction (attachment/ionization) using a monochromatic electron beam in combination with a quadrupole mass spectrometer. The ion yields were measured as a function of the incident electron energy between about 0 and 20 eV. As in the case of other biomolecules (nucleobases and amino acids), low energy electron attachment leads to destruction of the molecule via dissociative electron attachment reactions. In contrast to the previously investigated biomolecules dehydrogenation is not the predominant reaction channel for deoxyribose; the anion with the highest dissociative electron attachment (DEA) cross section of deoxyribose is formed by the release of neutral particles equal to two water molecules. Moreover, several of the DEA reactions proceed already with "zero energy" incident electrons. In addition, the fragmentation pattern of positively charged ions of deoxyribose also indicates strong decomposition of the molecule by incident electrons. For sugar the relative amount of fragment ions compared to that of the parent cation is about an order of magnitude larger than in the case of nucleobases. We determined an ionization energy value for C(5)H(10)O(4) (+) of 10.51+/-0.11 eV, which is in good agreement with ab initio calculations. For the fragment ion C(5)H(6)O(2) (+) we obtained a threshold energy lower than the ionization energy of the parent molecular ion. All of these results have important bearing for the question of what happens in exposure of living tissue to ionizing radiation. Energy deposition into irradiated cells produces electrons as the dominant secondary species. At an early time after irradiation these electrons exist as ballistic electrons with an initial energy distribution up to several tens of electron volts. It is just this energy regime for which we find in the present study rather characteristic differences in the outcome of electron interaction with the deoxyribose molecule compared to other nucleobases (studied earlier). Therefore, damage induced by these electrons to the DNA or RNA strands may start preferentially at the ribose backbone. In turn, damaged deoxyribose is known as a key intermediate in producing strand breaks, which are the most severe form of lesion in radiation damage to DNA and lead subsequently to cell death.
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Affiliation(s)
- S Ptasińska
- Institut für Ionenphysik, Leopold-Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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12
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Denifl S, Ptasińska S, Hanel G, Gstir B, Probst M, Scheier P, Märk TD. Electron attachment to gas-phase uracil. J Chem Phys 2006; 120:6557-65. [PMID: 15267547 DOI: 10.1063/1.1649724] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present results about dissociative electron attachment (DEA) to gas-phase uracil (U) for incident electron energies between 0 and 14 eV using a crossed electron/molecule beam apparatus. The most abundant negative ion formed via DEA is (U-H)-, where the resonance with the highest intensity appears at 1.01 eV. The anion yield of (U-H)- shows a number of peaks, which can be explained in part as being due to the formation of different (U-H)- isomers. Our results are compared with high level ab initio calculations using the G2MP2 method. There was no measurable amount of a parent ion U-. We also report the occurrence of 12 other fragments produced by dissociative electron attachment to uracil but with lower cross sections than (U-H)-. In addition we observed a parasitic contaminating process for conditions where uracil was introduced simultaneously with calibrant gases SF6 and CCl4 that leads to a sharp peak in the (U-H)- cross section close to 0 eV. For (U-H)- and all other fragments we determined rough measures for the absolute partial cross section yielding in the case of (U-H)- a peak value of sigma (at 1.01 eV)=3 x 10(-20) m2.
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Affiliation(s)
- S Denifl
- Institut für Ionenphysik, Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
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13
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Ptasińska S, Denifl S, Gohlke S, Scheier P, Illenberger E, Märk TD. Fragmentierung von Thymidin durch niederenergetische Elektronen: Implikationen für den Mechanismus von Einzelstrangbrüchen in DNA. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200503930] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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14
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Ptasińska S, Limão-Vieira P, Denifl S, Scheier P, Märk T. Electron attachment to monomeric and dimeric forms of glycolaldehyde. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2004.11.045] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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15
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Denifl S, Ptasińska S, Probst M, Hrušák J, Scheier P, Märk TD. Electron Attachment to the Gas-Phase DNA Bases Cytosine and Thymine. J Phys Chem A 2004. [DOI: 10.1021/jp049394x] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S. Denifl
- Institut fuer Ionenphysik, Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - S. Ptasińska
- Institut fuer Ionenphysik, Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - M. Probst
- Institut fuer Ionenphysik, Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - J. Hrušák
- Institut fuer Ionenphysik, Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - P. Scheier
- Institut fuer Ionenphysik, Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - T. D. Märk
- Institut fuer Ionenphysik, Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
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Tabrizchi M, Abedi A. A Novel Use of Negative Ion Mobility Spectrometry for Measuring Electron Attachment Rates. J Phys Chem A 2004. [DOI: 10.1021/jp048809b] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mahmoud Tabrizchi
- Chemistry Department, Isfahan University of Technology, Isfahan, 84154, Iran
| | - Azra Abedi
- Chemistry Department, Isfahan University of Technology, Isfahan, 84154, Iran
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17
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Pelc A, Sailer W, Scheier P, Märk TD, Illenberger E. Fragmentation of propanoic acid by subexcitation electrons. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.05.099] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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18
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Sailer W, Pelc A, Limão-Vieira P, Mason N, Limtrakul J, Scheier P, Probst M, Märk T. Low energy electron attachment to CH3CN. Chem Phys Lett 2003. [DOI: 10.1016/j.cplett.2003.09.118] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Pelc A, Sailer W, Matejcik S, Scheier P, Märk TD. Dissociative electron attachment to nitroethane: C2H5NO2. J Chem Phys 2003. [DOI: 10.1063/1.1607314] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Sailer W, Pelc A, Probst M, Limtrakul J, Scheier P, Illenberger E, Märk TD. Dissociative electron attachment to acetic acid (CH3COOH). Chem Phys Lett 2003. [DOI: 10.1016/s0009-2614(03)01285-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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21
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Voinov VG, Vasil'ev YV, Morré J, Barofsky DF, Deinzer ML, Gonin M, Egan TF, Führer K. A resonant electron capture time-of-flight MS with trochoidal electron monochromator. Anal Chem 2003; 75:3001-9. [PMID: 12964744 DOI: 10.1021/ac030019v] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A prototype electron monochromator (EM) reflectron time-of-flight (TOF) mass spectrometer has been constructed and demonstrated to record resonant electron capture (REC) mass spectra of electron-capturing compounds. The electron energy is ramped from -1.7 to +25 eV at a preset frequency, and the energy spread of the electron beam at 15 nA is 100 meV or better. Ions are orthogonally extracted into the analyzer at a frequency of up to 80 kHz while maintaining an upper m/z-limit of at least 300 and a mass resolving power of approximately 1000. A complete REC mass spectrum, which includes an effective yield versus electron energy curve for each negative ion formed from the compound being analyzed, typically takes several days to produce with a quadrupole or magnetic sector mass spectrometer. With the EM TOF described in this work, three-dimensional negative ion electron capture spectra are recorded in an interval on the order of only 1 s and displayed in real time. This new analytical capability could make it possible to perform GC REC mass spectrometry as well as easier (a) to measure the temperature dependence of REC cross sections, (b) to determine enthalpies of negative ion formation (accurate determination of the enthalpy of ion formation requires knowledge of the translational energy released during a dissociative capture event), and (c) to provide complete thermochemical descriptions of dissociative electron attachment by measuring ion lifetimes.
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Affiliation(s)
- Valery G Voinov
- Department of Chemistry and Environmental Health Sciences Center, Oregon State University, Corvallis, Oregon 97331, USA
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Matejcik S, Ipolyi I, Illenberger E. Temperature dependence of electron attachment to CH2ClBr: competition between Cl− and Br− formation. Chem Phys Lett 2003. [DOI: 10.1016/s0009-2614(03)00953-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Hanel G, Gstir B, Denifl S, Scheier P, Probst M, Farizon B, Farizon M, Illenberger E, Märk TD. Electron attachment to uracil: effective destruction at subexcitation energies. PHYSICAL REVIEW LETTERS 2003; 90:188104. [PMID: 12786046 DOI: 10.1103/physrevlett.90.188104] [Citation(s) in RCA: 210] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2002] [Indexed: 05/24/2023]
Abstract
We demonstrate that electrons at energies below the threshold for electronic excitation (<3 eV) effectively decompose gas phase uracil generating a mobile hydrogen radical and the corresponding closed shell uracil fragment anion (U-H)(-). The reaction is energetically driven by the large electron affinity of the (U-H) radical. This observation has significant consequences for the molecular picture of radiation damage, i.e., genotoxic effects or damage of living cells due to the secondary component of high energy radiation.
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Affiliation(s)
- G Hanel
- Institut für Ionenphysik der Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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24
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Drexel H, Sailer W, Grill V, Scheier P, Illenberger E, Märk TD. Electron attachment to C[sub 2]Cl[sub 4] and Trojan horse ionization. J Chem Phys 2003. [DOI: 10.1063/1.1559481] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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25
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26
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Sailer W, Drexel H, Pelc A, Grill V, Mason N, Illenberger E, Skalny J, Mikoviny T, Scheier P, Märk T. Low energy electron attachment to SF5CF3. Chem Phys Lett 2002. [DOI: 10.1016/s0009-2614(01)01367-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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27
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Sailer W, Tegeder P, Probst M, Drexel H, Grill V, Scheier P, Mason NJ, Illenberger E, Märk TD. Dissociation pathways in low energy (0–2 eV) electron attachment to Cl2O. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(01)00814-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Grill V, Drexel H, Sailer W, Lezius M, Märk TD. Operating principle of an electron monochromator in an axial magnetic field. JOURNAL OF MASS SPECTROMETRY : JMS 2001; 36:151-158. [PMID: 11288197 DOI: 10.1002/jms.113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Electron monochromators which are operated within an axial magnetic (guiding) field are especially suitable for the production of monochromatic electrons at low energies. Although in principle the technology of such devices has an appreciable historic background, we have discovered experimentally important new features, which cannot be understood using the previously published theories of operation. An in-depth study of the electron trajectories in a crossed electric and magnetic field using Simion1 showed a number of possible pitfalls, which have to be avoided in construction and operation. From our simulations we derived a novel design and operational method, which is currently under evaluation. We have already demonstrated that using this novel design an electron energy resolution of about 50 meV is realistic.
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Affiliation(s)
- V Grill
- Institut für Ionenphysik, Technikerstr. 25, A-6020 Innsbruck, Austria.
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Matejcik S, Stampfli P, Stamatovic A, Scheier P, Märk TD. Electron attachment to oxygen clusters studied with high energy resolution. J Chem Phys 1999. [DOI: 10.1063/1.479637] [Citation(s) in RCA: 23] [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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Muigg D, Denifl G, Stamatovic A, Echt O, Märk T. High-resolution electron ionization study of CO, (CO)2 and (CO)3: appearance energies and bond dissociation energies. Chem Phys 1998. [DOI: 10.1016/s0301-0104(98)00298-5] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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31
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Chu Y, Senn G, Matejcik S, Scheier P, Stampfli P, Stamatovic A, Illenberger E, Märk TD. Formation of NO− following electron attachment to NO clusters. Chem Phys Lett 1998. [DOI: 10.1016/s0009-2614(98)00420-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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