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Nakao T, Takasu R, Tsuchida H, Saito M, Majima T. Delayed fragmentation of isolated nucleobases induced by MeV ions. J Chem Phys 2024; 161:054302. [PMID: 39087542 DOI: 10.1063/5.0215222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Accepted: 07/17/2024] [Indexed: 08/02/2024] Open
Abstract
We evaluated the dissociation of isolated gas-phase nucleobase molecules induced by mega electron volt (MeV)-energy ions to gain fundamental insights into the reactions of nucleobases upon fast ion irradiation. We studied five nucleobase molecules-adenine, guanine, cytosine, thymine, and uracil-as gas-phase targets. We compared the fragmentation patterns obtained from carbon ion impacts with those obtained from proton impacts to clarify the effect of heavy ion irradiation. We also compared the results with electron impact and photoionization results. In addition, we identified several delayed fragmentation pathways by analyzing the correlation between fragment pairs generated from singly and doubly charged intermediate ions. To determine the lifetimes of delayed fragmentation from singly charged intermediate ions, we evaluated the detection efficiencies of the microchannel plate detector for the neutral fragment HCN as a function of kinetic energy using a new methodology. As the first demonstration of this method, we estimated the lifetimes of C5H5N5+ generated by 1.2-MeV C+ and 0.5-MeV H+ collisions to be 0.87 ± 0.43 and 0.67 ± 0.09 µs, respectively. These lifetimes were approximately one order of magnitude longer than those of the doubly charged intermediate ion C5H5N52+.
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Affiliation(s)
- T Nakao
- Department of Nuclear Engineering, Kyoto University, Kyoto 615-8540, Japan
| | - R Takasu
- Department of Nuclear Engineering, Kyoto University, Kyoto 615-8540, Japan
| | - H Tsuchida
- Department of Nuclear Engineering, Kyoto University, Kyoto 615-8540, Japan
- Quantum Science and Engineering Center, Kyoto University, Uji 611-0011, Japan
| | - M Saito
- Department of Nuclear Engineering, Kyoto University, Kyoto 615-8540, Japan
- Quantum Science and Engineering Center, Kyoto University, Uji 611-0011, Japan
| | - T Majima
- Department of Nuclear Engineering, Kyoto University, Kyoto 615-8540, Japan
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2
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Heathcote D, Robertson PA, Butler AA, Ridley C, Lomas J, Buffett MM, Bell M, Vallance C. Electron-induced dissociation dynamics studied using covariance-map imaging. Faraday Discuss 2022; 238:682-699. [PMID: 35781475 DOI: 10.1039/d2fd00033d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Recently, covariance analysis has found significant use in the field of chemical reaction dynamics. When coupled with data from product time-of-flight mass spectrometry and/or multi-mass velocity-map imaging, it allows us to uncover correlations between two or more ions formed from the same parent molecule. While the approach has parallels with coincidence measurements, covariance analysis allows experiments to be performed at much higher count rates than traditional coincidence methods. We report results from electron-molecule crossed-beam experiments, in which covariance analysis is used to elucidate the dissociation dynamics of multiply-charged ions formed by electron ionisation over the energy range from 50 to 300 eV. The approach is able to isolate signal contributions from multiply charged ions even against a very large 'background' of signal arising from dissociation of singly-charged parent ions. Covariance between the product time-of-flight spectra identifies pairs of fragments arising from the same parent ions, while covariances between the velocity-map images ('recoil-frame covariances') reveal the relative velocity distributions of the ion pairs. We show that recoil-frame covariance analysis can be used to distinguish between multiple plausible dissociation mechanisms, including multi-step processes, and that the approach becomes particularly powerful when investigating the fragmentation dynamics of larger molecules with a higher number of possible fragmentation pathways.
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Affiliation(s)
- David Heathcote
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Patrick A Robertson
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Alexander A Butler
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Cian Ridley
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - James Lomas
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Madeline M Buffett
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Megan Bell
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Claire Vallance
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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3
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Singh R, Pal S. (e,2e) Partial Ionization Cross Sections for n-Butane. J Phys Chem A 2021; 125:8691-8698. [PMID: 34553590 DOI: 10.1021/acs.jpca.1c06237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Energy-dependent partial differential ionization cross sections at constant incident electron energies and their integral cross sections for n-butane (n-C4H10) by electron impact corresponding to the formation of various major cations are calculated using a revisited Jain-Khare semiempirical formulation. Averaged energies of the secondary electrons are also derived from the differential cross sections. The ionization rate coefficients as a function of the temperature are evaluated from integral partial ionization cross sections and Maxwell-Boltzmann energy distributions. Calculations of cross sections include the Bethe analytical extrapolation at higher energies up to 6 keV. A satisfactory agreement of the calculated partial and total ionization cross sections with the available experimental and theoretical results is noted.
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Affiliation(s)
- Rajbeer Singh
- Department of Physics, M. M. H. College, Ghaziabad-201001, UP, India
| | - Satyendra Pal
- Department of Physics, M. M. H. College, Ghaziabad-201001, UP, India
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Formation of H 3+ from ethane dication induced by electron impact. Commun Chem 2020; 3:160. [PMID: 36703403 PMCID: PMC9814254 DOI: 10.1038/s42004-020-00415-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 10/19/2020] [Indexed: 01/29/2023] Open
Abstract
Hydrogen migration plays an important role in the chemistry of hydrocarbons which considerably influences their chemical functions. The migration of one or more hydrogen atoms occurring in hydrocarbon cations has an opportunity to produce the simplest polyatomic molecule, i.e. H3+. Here we present a combined experimental and theoretical study of H3+ formation dynamics from ethane dication. The experiment is performed by 300 eV electron impact ionization of ethane and a pronounced yield of H3+ + C2H3+ coincidence channel is observed. The quantum chemistry calculations show that the H3+ formation channel can be opened on the ground-state potential energy surface of ethane dication via transition state and roaming mechanisms. The ab initio molecular dynamics simulation shows that the H3+ can be generated in a wide time range from 70 to 500 fs. Qualitatively, the trajectories of the fast dissociation follow the intrinsic reaction coordinate predicted by the conventional transition state theory. The roaming mechanism, compared to the transition state, occurs within a much longer timescale accompanied by nuclear motion of larger amplitude.
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5
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Coherent vibrations in methanol cation probed by periodic H3+ ejection after double ionization. Commun Chem 2018. [DOI: 10.1038/s42004-017-0006-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Shen Z, Wang E, Gong M, Shan X, Chen X. Fragmentation dynamics of carbonyl sulfide in collision with 500 eV electron. J Chem Phys 2016; 145:234303. [PMID: 28010080 DOI: 10.1063/1.4972064] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The fragmentation dynamics of OCSq+ (q = 2, 3, 4) induced by electron collision at an impact energy of 500 eV is studied. By using the momentum imaging technique, the three dimensional momentum vectors of all the fragments are obtained, which enables us to analyse both the kinetic energy release and the momentum correlations for a certain fragmentation channel. Up to fifteen dissociation channels are analyzed including six, five, and four channels for two-body, and incomplete and complete three-body Coulomb fragmentations. For three-body dissociation, the fragmentation mechanisms are investigated with the help of Dalitz plot and Newton diagram. It is found that the sequential fragmentation involves in OCS2+→O+C++S+ with S+ emitted first and in OCS3+→O++C++S+ with O-C and C-S bonds breaking first. The remaining channels, however, always dissociate through a concerted mechanism. The relative intensities of the channels are also presented in this work.
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Affiliation(s)
- Zhenjie Shen
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Enliang Wang
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Maomao Gong
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xu Shan
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiangjun Chen
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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A boron–boron coupling reaction between two ethyl cation analogues. Nat Chem 2013; 5:1029-34. [DOI: 10.1038/nchem.1776] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 09/04/2013] [Indexed: 11/08/2022]
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Sun S, Yang Y, Zhang J, Wu H, Chen Y, Zhang S, Jia T, Wang Z, Sun Z. Ejection of triatomic molecular ion from methyl chloride in an intense femtosecond laser field. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.06.068] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Wolff W, Sigaud L, Montenegro EC, de Jesus VLB, Cavasso Filho RL, Pilling S, Santos ACF. Ionization and Fragmentation of Methane Induced by 40 eV to 480 eV Synchrotron Radiation: From Valence to Beyond Core Electron Ionization. J Phys Chem A 2012; 117:56-66. [DOI: 10.1021/jp309187d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- W. Wolff
- Instituto de Física, Universidade Federal do Rio de Janeiro, PO 68528, 21941-972 Rio de Janeiro,
RJ, Brazil
| | - L. Sigaud
- Instituto de Física, Universidade Federal do Rio de Janeiro, PO 68528, 21941-972 Rio de Janeiro,
RJ, Brazil
| | - E. C. Montenegro
- Instituto de Física, Universidade Federal do Rio de Janeiro, PO 68528, 21941-972 Rio de Janeiro,
RJ, Brazil
| | - V. L. B. de Jesus
- Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro (IFRJ), Campus Nilópolis, R.
Lucio Tavares 1045, 26530-060 Nilópolis, RJ, Brazil
| | - R. L Cavasso Filho
- Universidade Federal do ABC, Rua Catequese 242, 09090-400, Santo André,
SP, Brazil
| | - S. Pilling
- Universidade do Vale do Paraíba, UNIVAP, Av.
Shishima Hifumi 2911, Campus Urbanova, 12244 000, São José
dos Campos, SP, Brazil
| | - A. C. F. Santos
- Instituto de Física, Universidade Federal do Rio de Janeiro, PO 68528, 21941-972 Rio de Janeiro,
RJ, Brazil
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Alıç TY, Şükür Kılıç H, Durmuş H, Doğan M, Ledingham KWD. A mass spectrometric investigation of isomers of butane. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:893-905. [PMID: 22396025 DOI: 10.1002/rcm.6184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
RATIONALE Butane is an important industrial chemical in which photo-processes are very important for the initiation of reactions. Recent advances in nanosecond pulsed laser technology have led to high laser intensities being available to researchers to enable these photo-processes to be studied in compounds such as butane. METHODS The photo-decomposition, dissociation and combustion mechanisms in the neutral butane molecule have been studied in detail, by investigating the multiphoton (MP) dissociative ionisation of its n- and i-isomers, using a time-of-flight mass spectrometer connected to a high power nanosecond laser system. The laser used was a Nd:Yag with a 5 ns pulse width operated at the fundamental wavelength (1064 nm) and the doubled and tripled wavelengths (532 nm and 355 nm). The fragmentation patterns for the isomers were determined for the three wavelengths as a function of laser intensity. Similar laser intensities of between 10(10) and 10(13) W/cm(2) were used at the three wavelengths: 1064, 532 and 355 nm. RESULTS The mass spectra of each isomer of the butane molecule display a very weak molecular ion and are dominated by fragment ion peaks. The degree of fragmentation increases as the laser intensity increases. CONCLUSIONS Depending on the wavelength some significant differences in the mass spectra of the two isomers were detected and it has been concluded that the isomerisation of i-butane to n-butane is a process which is faster than the duration of the laser pulse used.
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Affiliation(s)
- Tuğbahan Yılmaz Alıç
- University of Selcuk, Faculty of Science, Department of Physics, Konya 42031, Turkey
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Hoshina K, Kawamura H, Tsuge M, Tamiya M, Ishiguro M. Metastable decomposition and hydrogen migration of ethane dication produced in an intense femtosecond near-infrared laser field. J Chem Phys 2011; 134:064324. [DOI: 10.1063/1.3549137] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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12
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Ward MD, King SJ, Price SD. Electron ionization of methane: The dissociation of the methane monocation and dication. J Chem Phys 2011; 134:024308. [DOI: 10.1063/1.3519636] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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Douglas KM, Price SD. Studies of the fragmentation of the monocation and dication of methanol. J Chem Phys 2009; 131:224305. [PMID: 20001034 DOI: 10.1063/1.3266940] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Relative partial ionization cross sections and precursor-specific relative partial ionization cross sections for fragment ions formed by electron ionization of methanol have been measured using time-of-flight mass spectrometry coupled with a two-dimensional ion coincidence technique. Relative cross sections are reported for ionizing energies from 30 to 200 eV. Good agreement is found between our data and one set of recently published absolute partial ionization cross sections. Conversely, discrepancies are observed with another set of recently published data; we attribute these discrepancies to the loss of translationally energetic fragment ions. Our precursor-specific cross sections allow the contribution from single and double ionization to the individual fragment ion yields, following ionization of methanol, to be quantified for the first time. Our analysis shows that the contribution of double ionization to the total ion yield reaches a maximum of 20% between 150 and 200 eV.
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Affiliation(s)
- Kevin M Douglas
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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Hoshina K, Furukawa Y, Okino T, Yamanouchi K. Efficient ejection of H3+ from hydrocarbon molecules induced by ultrashort intense laser fields. J Chem Phys 2008; 129:104302. [DOI: 10.1063/1.2973588] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Liu X, Shemansky DE. Analysis of electron impact ionization properties of methane. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005ja011454] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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16
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Di Palma T, Apicella B, Armenante M, Velotta R, Wang X, Spinelli N. Ion kinetic energy distributions and cross sections for the electron impact ionization of ethyl tert-butyl ether. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.09.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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17
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Wang P, Vidal CR, Geith J, Klapötke TM, Fuss W. Dissociation of multiply ionized isocyanic acid through electron impact. J Chem Phys 2004; 120:123-8. [PMID: 15267268 DOI: 10.1063/1.1630310] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The dissociation of singly to triply ionized isocyanic acid (HNCO) has been investigated by two- and three-dimensional covariance mapping techniques through electron impact ionization at an electron energy of 200 eV. The absolute cross sections for the various dissociation channels of up to triply ionized HNCO have been measured. The HNCO dications dissociate mostly into ion pairs, while the HNCO trications dissociate mostly into ion triples, both through all the possible bond cleavages and charge allocations. Some major ion-pair dissociation channels of HNCO2+ are supposed to be sequential dissociation through initial charge separation. The metastable decay traces caused by HNCO(2+)-->H(+)+NCO+ and HNCO(+)-->HCO(+)+N have been observed on the covariance map.
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Affiliation(s)
- Pengqian Wang
- Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany.
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Wang P, Vidal CR. Dissociation of multiply ionized carbonyl sulfide due to electron impact. J Chem Phys 2003. [DOI: 10.1063/1.1554738] [Citation(s) in RCA: 13] [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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