1
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Clarke CJ, Verlet JRR. Dynamics of Anions: From Bound to Unbound States and Everything In Between. Annu Rev Phys Chem 2024; 75:89-110. [PMID: 38277700 DOI: 10.1146/annurev-physchem-090722-125031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2024]
Abstract
Gas-phase anions present an ideal playground for the exploration of excited-state dynamics. They offer control in terms of the mass, extent of solvation, internal temperature, and conformation. The application of a range of ion sources has opened the field to a vast array of anionic systems whose dynamics are important in areas ranging from biology to star formation. Here, we review recent experimental developments in the field of anion photodynamics, demonstrating the detailed insight into photodynamical and electron-capture processes that can be uncovered. We consider the electronic and nuclear ultrafast dynamics of electronically bound excited states along entire reaction coordinates; electronically unbound states showing that photochemical concepts, such as chromophores and Kasha's rule, are transferable to electron-driven chemistry; and nonvalence states that straddle the interface between bound and unbound states. Finally, we consider likely developments that are sure to keep the field of anion dynamics buoyant and impactful.
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Affiliation(s)
- Connor J Clarke
- Department of Chemistry, Durham University, Durham, United Kingdom;
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham, United Kingdom;
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2
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Asplund M, Koga M, Wu YJ, Neumark DM. Time-resolved photoelectron spectroscopy of iodide-4-thiouracil cluster: The ππ* state as a doorway for electron attachment. J Chem Phys 2024; 160:054301. [PMID: 38299627 DOI: 10.1063/5.0187557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 01/09/2024] [Indexed: 02/02/2024] Open
Abstract
The photophysics of thiobases-nucleobases in which one or more oxygen atoms are replaced with sulfur atoms- vary greatly depending on the location of sulfonation. Not only are direct dynamics of a neutral thiobase impacted, but also the dynamics of excess electron accommodation. In this work, time-resolved photoelectron spectroscopy is used to measure binary anionic clusters of iodide and 4-thiouracil, I- · 4TU. We investigate charge transfer dynamics driven by excitation at 3.88 eV, corresponding to the lowest ππ* transition of the thiouracil, and at 4.16 eV, near the cluster vertical detachment energy. The photoexcited state dynamics are probed by photodetachment with 1.55 and 3.14 eV pulses. Excitation at 3.88 eV leads to a signal from a valence-bound ion only, indicating a charge accommodation mechanism that does not involve a dipole-bound anion as an intermediate. Excitation at 4.16 eV rapidly gives rise to dipole-bound and valence-bound ion signals, with a second rise in the valence-bound signal corresponding to the decay of the dipole-bound signal. The dynamics associated with the low energy ππ* excitation of 4-thiouracil provide a clear experimental proof for the importance of localized excitation and electron backfilling in halide-nucleobase clusters.
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Affiliation(s)
- Megan Asplund
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Masafumi Koga
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Ying Jung Wu
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Daniel M Neumark
- Department of Chemistry, University of California, Berkeley, California 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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3
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McGee CJ, McGinnis KR, Jarrold CC. Anion Photoelectron Imaging Spectroscopy of C 6HF 5-, C 6F 6-, and the Absence of C 6H 2F 4. J Phys Chem A 2023; 127:8556-8565. [PMID: 37816145 DOI: 10.1021/acs.jpca.3c04016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Substituents have a profound effect on the electronic structure of the benzene molecule. In this paper, we present new photoelectron spectra of the C5HF5- molecular anion, to test predictions [ Int. J. Quant. Chem. 2017, 188, e25504] that pentafluorobenzene has a positive electron affinity, as hexafluorobenzene was already known to have. The PE spectrum of C6HF5- exhibits a broad and vibrationally unresolved band due to significant differences between the structure of the anion and the neutral. The vertical detachment energy (VDE) of C5HF5- is determined to be 1.33 ± 0.05 eV, and the lowest binding energy at which the signal is observed is 0.53 ± 0.05 eV, which, if taken as the electron affinity, is in good agreement with the computed value. In addition, we attempted to generate intact C6H2F4- molecular ions using the 1,2,3,4-tetrafluorobenzene, 1,2,3,5-tetrafluorobenzene, and 1,2,4,5-tetrafluorobenzene precursors, as tetrafluorobenzene was predicted to have a near-zero but marginally positive electron affinity. Using a photoemission anion source, we were not able to produce the intact tetrafluorobenzene anion. Density functional theory calculations support a more detailed discussion of the impact of fluorine substitution on the electronic structure of these species.
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Affiliation(s)
- Conor J McGee
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Kristen Rose McGinnis
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Caroline Chick Jarrold
- Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
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4
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Koga M, Asplund M, Neumark DM. Electron attachment dynamics following UV excitation of iodide-2-thiouracil complexes. J Chem Phys 2022; 156:244302. [DOI: 10.1063/5.0098280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dynamics of low energy electron attachment to the thio-substituted uracil analog 2-thiouracil are investigated using time-resolved photoelectron spectroscopy (TRPES) of iodide·2-thiouracil (I -·2TU) binary clusters. In these experiments, the anions are excited at pump energies of 4.16 and 4.73 eV, and the ensuing dynamics are probed by photodetachment at 1.59 and 3.18 eV. Upon excitation near the vertical detachment energy (4.16 eV), dipole bound (DB) and valence bound (VB) anion signals appear almost instantaneously, and the DB state of the 2TU anion undergoes ultrafast decay (~50 fs). At 4.73 eV, there is no evidence for a DB state, but features attributed to two VB states are seen. The transient negative ions formed by photoexcitation decay by autodetachment and I- fragmentation. The I- dissociation rates and their dependence on excitation energy agree reasonably well with the Rice-Ramsperger-Kassel-Marcus calculations. Notable differences with respect to TRPES of the related iodide-uracil anion are observed and discussed.
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Affiliation(s)
- Masafumi Koga
- University of California Berkeley Department of Chemistry, United States of America
| | - Megan Asplund
- University of California Berkeley Department of Chemistry, United States of America
| | - Daniel M. Neumark
- Department of Chemistry, University of California Berkeley Department of Chemistry, United States of America
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5
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Liu C, Zheng Y, Sanche L. Damage Induced to DNA and Its Constituents by 0-3 eV UV Photoelectrons †. Photochem Photobiol 2021; 98:546-563. [PMID: 34767635 DOI: 10.1111/php.13559] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 11/07/2021] [Indexed: 11/28/2022]
Abstract
The complex physical and chemical interactions between DNA and 0-3 eV electrons released by UV photoionization can lead to the formation of various lesions such as base modifications and cleavage, crosslinks and single strand breaks. Furthermore, in the presence of platinum chemotherapeutic agents, these electrons can cause clustered lesions, including double strand breaks. We explain the mechanisms responsible for these damages via the production 0-3 eV electrons by UVC radiation, and by UV photons of any wavelengths, when they are produced by photoemission from nanoparticles lying within about 10 nm from DNA. We review experimental evidence showing that a single 0-3 eV electron can produce these damages. The foreseen benefits UV-irradiation of nanoparticles targeted to the cell nucleus are mentioned in the context of cancer therapy, as well as the potential hazards to human health when they are present in cells.
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Affiliation(s)
- Chaochao Liu
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, China
| | - Yi Zheng
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, China
| | - Léon Sanche
- Département de Médecine Nucléaire et Radiobiologie et Centre de Recherche Clinique, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC, Canada
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Gao Y, Zheng Y, Sanche L. Low-Energy Electron Damage to Condensed-Phase DNA and Its Constituents. Int J Mol Sci 2021; 22:7879. [PMID: 34360644 PMCID: PMC8345953 DOI: 10.3390/ijms22157879] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/30/2021] [Accepted: 06/30/2021] [Indexed: 11/18/2022] Open
Abstract
The complex physical and chemical reactions between the large number of low-energy (0-30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.
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Affiliation(s)
- Yingxia Gao
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350116, China;
| | - Yi Zheng
- State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350116, China;
| | - Léon Sanche
- Département de Médecine Nucléaire et Radiobiologie et Centre de Recherche Clinique, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
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7
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Castellani ME, Verlet JRR. Intramolecular Photo-Oxidation as a Potential Source to Probe Biological Electron Damage: A Carboxylated Adenosine Analogue as Case Study. Molecules 2021; 26:2877. [PMID: 34067988 PMCID: PMC8152231 DOI: 10.3390/molecules26102877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/05/2021] [Accepted: 05/10/2021] [Indexed: 11/16/2022] Open
Abstract
A carboxylated adenosine analog (C-Ado-) has been synthesized and probed via time-resolved photoelectron spectroscopy in order to induce intra-molecular charge transfer from the carboxylic acid moiety to the nucleobase. Intra-molecular charge transfer can be exploited as starting point to probe low-energy electron (LEE) damage in DNA and its derivatives. Time-dependent density functional theory (TD-DFT) calculations at the B3LYP-6311G level of theory have been performed to verify that the highest occupied molecular orbital (HOMO) was located on carboxylic acid and that the lowest occupied molecular orbital (LUMO) was on the nucleobase. Hence, the carboxylic acid could work as electron source, whilst the nucleobase could serve the purpose of electron acceptor. The dynamics following excitation at 4.66 eV (266 nm) were probed using time-resolved photoelectron spectroscopy using probes at 1.55 eV (800 nm) and 3.10 eV (400 nm). The data show rapid decay of the excited state population and, based on the similarity of the overall dynamics to deoxy-adenosine monophosphate (dAMP-), it appears that the dominant decay mechanism is internal conversion following 1ππ* excitation of the nucleobase, rather than charge-transfer from the carboxylic acid to the nucleobase.
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8
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Yuan DF, Zhang YR, Qian CH, Liu Y, Wang LS. Probing the Dipole-Bound State in the 9-Phenanthrolate Anion by Photodetachment Spectroscopy, Resonant Two-Photon Photoelectron Imaging, and Resonant Photoelectron Spectroscopy. J Phys Chem A 2021; 125:2967-2976. [DOI: 10.1021/acs.jpca.1c01563] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Dao-Fu Yuan
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Yue-Rou Zhang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Chen-Hui Qian
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Yuan Liu
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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9
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Uleanya KO, Dessent CEH. Investigating the mapping of chromophore excitations onto the electron detachment spectrum: photodissociation spectroscopy of iodide ion-thiouracil clusters. Phys Chem Chem Phys 2021; 23:1021-1030. [PMID: 33428696 DOI: 10.1039/d0cp05920j] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Laser photodissociation spectroscopy (3.1-5.7 eV) has been applied to iodide complexes of the non-native nucleobases, 2-thiouracil (2-TU), 4-thiouracil (4-TU) and 2,4-thiouracil (2,4-TU), to probe the excited states and intracluster electron transfer as a function of sulphur atom substitution. Photodepletion is strong for all clusters (I-·2-TU, I-·4-TU and I-·2,4-TU) and is dominated by electron detachment processes. For I-·4-TU and I-·2,4-TU, photodecay is accompanied by formation of the respective molecular anions, 4-TU- and 2,4-TU-, behaviour that is not found for other nucleobases. Notably, the I-·2TU complex does not fragment with formation of its molecular anion. We attribute the novel formation of 4-TU- and 2,4-TU- to the fact that these valence anions are significantly more stable than 2-TU-. We observe further similar behaviour for I-·4-TU and I-·2,4-TU relating to the general profile of their photodepletion spectra, since both strongly resemble the intrinsic absorption spectra of the respective uncomplexed thiouracil molecule. This indicates that the nucleobase chromophore excitations are determining the clusters' spectral profile. In contrast, the I-·2-TU photodepletion spectrum is dominated by the electron detachment profile, with the near-threshold dipole-bound excited state being the only distinct spectral feature. We discuss these observations in the context of differences in the dipole moments of the thionucleobases, and their impact on the coupling of nucleobase-centred transitions onto the electron detachment spectrum.
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Affiliation(s)
- Kelechi O Uleanya
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
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10
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Anstöter CS, Matsika S. Understanding the Interplay between the Nonvalence and Valence States of the Uracil Anion upon Monohydration. J Phys Chem A 2020; 124:9237-9243. [DOI: 10.1021/acs.jpca.0c07407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Cate S. Anstöter
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Spiridoula Matsika
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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11
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Kunin A, McGraw VS, Lunny KG, Neumark DM. Time-resolved dynamics in iodide-uracil-water clusters upon excitation of the nucleobase. J Chem Phys 2019; 151:154304. [PMID: 31640364 DOI: 10.1063/1.5120706] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dynamics of iodide-uracil-water (I-·U·H2O) clusters following π-π* excitation of the nucleobase are probed using time-resolved photoelectron spectroscopy. Photoexcitation of this cluster at 4.77 eV results in electron transfer from the iodide moiety to the uracil, creating a valence-bound anion within the cross correlation of the pump and probe laser pulses. This species can decay by a number of channels, including autodetachment and dissociation to I- or larger anion fragments. Comparison of the energetics of the photoexcited cluster and its decay dynamics with those of the bare iodide-uracil (I-·U) complex provides a sensitive probe of the effects of microhydration on these species.
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Affiliation(s)
- Alice Kunin
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Valerie S McGraw
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Katharine G Lunny
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Daniel M Neumark
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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12
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Cercola R, Uleanya KO, Dessent CEH. Electron detachment dynamics of the iodide-guanine cluster: does ionization occur from the iodide or from guanine? Mol Phys 2019. [DOI: 10.1080/00268976.2019.1679402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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13
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Kunin A, Neumark DM. Time-resolved radiation chemistry: femtosecond photoelectron spectroscopy of electron attachment and photodissociation dynamics in iodide-nucleobase clusters. Phys Chem Chem Phys 2019; 21:7239-7255. [PMID: 30855623 DOI: 10.1039/c8cp07831a] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Iodide-nucleobase (I-·N) clusters studied by time-resolved photoelectron spectroscopy (TRPES) are an opportune model system for examining radiative damage of DNA induced by low-energy electrons. By initiating charge transfer from iodide to the nucleobase and following the dynamics of the resulting transient negative ions (TNIs) with femtosecond time resolution, TRPES provides a novel window into the chemistry triggered by the attachment of low-energy electrons to nucleobases. In this Perspective, we examine and compare the dynamics of electron attachment, autodetachment, and photodissociation in a variety of I-·N clusters, including iodide-uracil (I-·U), iodide-thymine (I-·T), iodide-uracil-water (I-·U·H2O), and iodide-adenine (I-·A), to develop a more unified representation of our understanding of nucleobase TNIs. The experiments probe whether dipole-bound or valence-bound TNIs are formed initially and the subsequent time evolution of these species. We also provide an outlook for forthcoming applications of TRPES to larger iodide-containing complexes to enable the further investigation of microhydration dynamics in nucleobases, as well as electron attachment and photodissociation in more complex nucleic acid constituents.
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Affiliation(s)
- Alice Kunin
- Department of Chemistry, University of California, Berkeley, California 94720, USA.
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14
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Cercola R, Matthews E, Dessent CEH. Near-threshold electron transfer in anion-nucleobase clusters: does the identity of the anion matter? Mol Phys 2019. [DOI: 10.1080/00268976.2019.1596327] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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15
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Kunin A, Li WL, Neumark DM. Dynamics of electron attachment and photodissociation in iodide-uracil-water clusters via time-resolved photoelectron imaging. J Chem Phys 2018; 149:084301. [PMID: 30193511 DOI: 10.1063/1.5040673] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The dynamics of low energy electron attachment to monohydrated uracil are investigated using time-resolved photoelectron imaging to excite and probe iodide-uracil-water (I-·U·H2O) clusters. Upon photoexcitation of I-·U·H2O at 4.38 eV, near the measured cluster vertical detachment energy of 4.40 eV ± 0.05 eV, formation of both the dipole bound (DB) anion and valence bound (VB) anion of I-·U·H2O is observed and characterized using a probe photon energy of 1.58 eV. The measured binding energies for both anions are larger than those of the non-hydrated iodide-uracil (I-·U) counterparts, indicating that the presence of water stabilizes the transient negative ions. The VB anion exhibits a somewhat delayed 400 fs rise when compared to I-·U, suggesting that partial conversion of the DB anion to form the VB anion at early times is promoted by the water molecule. At a higher probe photon energy, 3.14 eV, I- re-formation is measured to be the major photodissociation channel. This product exhibits a bi-exponential rise; it is likely that the fast component arises from DB anion decay by internal conversion to the anion ground state followed by dissociation to I-, and the slow component arises from internal conversion of the VB anion.
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Affiliation(s)
- Alice Kunin
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Wei-Li Li
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Daniel M Neumark
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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16
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Lyle J, Chandramoulee SR, Hart CA, Mabbs R. Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F. J Vis Exp 2018:57989. [PMID: 30102284 PMCID: PMC6126567 DOI: 10.3791/57989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound electrons with neutral molecules/atoms. State-of-the-art in vacuo anion generation techniques allow application to a broad range of atomic, molecular, and cluster anion systems. These are separated and selected using time-of-flight mass spectrometry. Electrons are removed by linearly polarized photons (photo detachment) using table-top laser sources which provide ready access to excitation energies from the infra-red to the near ultraviolet. Detecting the photoelectrons with a velocity mapped imaging lens and position sensitive detector means that, in principle, every photoelectron reaches the detector and the detection efficiency is uniform for all kinetic energies. Photoelectron spectra extracted from the images via mathematical reconstruction using an inverse Abel transformation reveal details of the anion internal energy state distribution and the resultant neutral energy states. At low electron kinetic energy, typical resolution is sufficient to reveal energy level differences on the order of a few millielectron-volts, i.e., different vibrational levels for molecular species or spin-orbit splitting in atoms. Photoelectron angular distributions extracted from the inverse Abel transformation represent the signatures of the bound electron orbital, allowing more detailed probing of electronic structure. The spectra and angular distributions also encode details of the interactions between the outgoing electron and the residual neutral species subsequent to excitation. The technique is illustrated by the application to an atomic anion (F-), but it can also be applied to the measurement of molecular anion spectroscopy, the study of low lying anion resonances (as an alternative to scattering experiments) and femtosecond (fs) time resolved studies of the dynamic evolution of anions.
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Affiliation(s)
- Justin Lyle
- Department of Chemistry, Washington University in St. Louis
| | | | - C Annie Hart
- Department of Chemistry, Washington University in St. Louis
| | - Richard Mabbs
- Department of Chemistry, Washington University in St. Louis;
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17
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Matthews E, Cercola R, Mensa-Bonsu G, Neumark DM, Dessent CEH. Photoexcitation of iodide ion-pyrimidine clusters above the electron detachment threshold: Intracluster electron transfer versus nucleobase-centred excitations. J Chem Phys 2018; 148:084304. [PMID: 29495768 DOI: 10.1063/1.5018168] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Laser photodissociation spectroscopy of the I-·thymine (I-·T) and I-·cytosine (I-·C) nucleobase clusters has been conducted for the first time across the regions above the electron detachment thresholds to explore the excited states and photodissociation channels. Although photodepletion is strong, only weak ionic photofragment signals are observed, indicating that the clusters decay predominantly by electron detachment. The photodepletion spectra of the I-·T and I-·C clusters display a prominent dipole-bound excited state (I) in the vicinity of the vertical detachment energy (∼4.0 eV). Like the previously studied I-·uracil (I-·U) cluster [W. L. Li et al., J. Chem. Phys. 145, 044319 (2016)], the I-·T cluster also displays a second excited state (II) centred at 4.8 eV, which we similarly assign to a π-π* nucleobase-localized transition. However, no distinct higher-energy absorption bands are evident in the spectra of the I-·C. Time-dependent density functional theory (TDDFT) calculations are presented, showing that while each of the I-·T and I-·U clusters displays a single dominant π-π* nucleobase-localized transition, the corresponding π-π* nucleobase transitions for I-·C are split across three separate weaker electronic excitations. I- and deprotonated nucleobase anion photofragments are observed upon photoexcitation of both I-·U and I-·T, with the action spectra showing bands (at 4.0 and 4.8 eV) for both the I- and deprotonated nucleobase anion production. The photofragmentation behaviour of the I-·C cluster is distinctive as its I- photofragment displays a relatively flat profile above the expected vertical detachment energy. We discuss the observed photofragmentation profiles of the I-·pyrimidine clusters, in the context of the previous time-resolved measurements, and conclude that the observed photoexcitations are primarily consistent with intracluster electron transfer dominating in the near-threshold region, while nucleobase-centred excitations dominate close to 4.8 eV. TDDFT calculations suggest that charge-transfer transitions [Iodide n (5p6) → Uracil σ*] may contribute to the cluster absorption profile across the scanned spectral region, and the possible role of these states is also discussed.
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Affiliation(s)
- Edward Matthews
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Rosaria Cercola
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Golda Mensa-Bonsu
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Daniel M Neumark
- Department of Chemistry, University of California, Berkeley, California 94720, USA and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Caroline E H Dessent
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
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18
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Fennimore MA, Matsika S. Electronic Resonances of Nucleobases Using Stabilization Methods. J Phys Chem A 2018; 122:4048-4057. [DOI: 10.1021/acs.jpca.8b01523] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Mark A. Fennimore
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Spiridoula Matsika
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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19
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Li WL, Kunin A, Matthews E, Yoshikawa N, Dessent CEH, Neumark DM. Photodissociation dynamics of the iodide-uracil (I(-)U) complex. J Chem Phys 2017; 145:044319. [PMID: 27475373 DOI: 10.1063/1.4959858] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Photofragment action spectroscopy and femtosecond time-resolved photoelectron imaging are utilized to probe the dissociation channels in iodide-uracil (I(-) ⋅ U) binary clusters upon photoexcitation. The photofragment action spectra show strong I(-) and weak [U-H](-) ion signal upon photoexcitation. The action spectra show two bands for I(-) and [U-H](-) production peaking around 4.0 and 4.8 eV. Time-resolved experiments measured the rate of I(-) production resulting from excitation of the two bands. At 4.03 eV and 4.72 eV, the photoelectron signal from I(-) exhibits rise times of 86 ± 7 ps and 36 ± 3 ps, respectively. Electronic structure calculations indicate that the lower energy band, which encompasses the vertical detachment energy (4.11 eV) of I(-)U, corresponds to excitation of a dipole-bound state of the complex, while the higher energy band is primarily a π-π(∗) excitation on the uracil moiety. Although the nature of the two excited states is very different, the long lifetimes for I(-) production suggest that this channel results from internal conversion to the I(-) ⋅ U ground state followed by evaporation of I(-). This hypothesis was tested by comparing the dissociation rates to Rice-Ramsperger-Kassel-Marcus calculations.
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Affiliation(s)
- Wei-Li Li
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Alice Kunin
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Edward Matthews
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Naruo Yoshikawa
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Caroline E H Dessent
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Daniel M Neumark
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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20
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Stephansen AB, King SB, Yokoi Y, Minoshima Y, Li WL, Kunin A, Takayanagi T, Neumark DM. Dynamics of dipole- and valence bound anions in iodide-adenine binary complexes: A time-resolved photoelectron imaging and quantum mechanical investigation. J Chem Phys 2016; 143:104308. [PMID: 26374036 DOI: 10.1063/1.4929995] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Dipole bound (DB) and valence bound (VB) anions of binary iodide-adenine complexes have been studied using one-color and time-resolved photoelectron imaging at excitation energies near the vertical detachment energy. The experiments are complemented by quantum chemical calculations. One-color spectra show evidence for two adenine tautomers, the canonical, biologically relevant A9 tautomer and the A3 tautomer. In the UV-pump/IR-probe time-resolved experiments, transient adenine anions can be formed by electron transfer from the iodide. These experiments show signals from both DB and VB states of adenine anions formed on femto- and picosecond time scales, respectively. Analysis of the spectra and comparison with calculations suggest that while both the A9 and A3 tautomers contribute to the DB signal, only the DB state of the A3 tautomer undergoes a transition to the VB anion. The VB anion of A9 is higher in energy than both the DB anion and the neutral, and the VB anion is therefore not accessible through the DB state. Experimental evidence of the metastable A9 VB anion is instead observed as a shape resonance in the one-color photoelectron spectra, as a result of UV absorption by A9 and subsequent electron transfer from iodide into the empty π-orbital. In contrast, the iodide-A3 complex constitutes an excellent example of how DB states can act as doorway state for VB anion formation when the VB state is energetically available.
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Affiliation(s)
- Anne B Stephansen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 København Ø, Denmark
| | - Sarah B King
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Yuki Yokoi
- Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Yusuke Minoshima
- Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Wei-Li Li
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Alice Kunin
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Toshiyuki Takayanagi
- Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Daniel M Neumark
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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21
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Minoshima Y, Seki Y, Takayanagi T, Shiga M. Effects of temperature and isotopic substitution on electron attachment dynamics of guanine–cytosine base pair: Ring-polymer and classical molecular dynamics simulations. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2016.02.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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22
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King SB, Stephansen AB, Yokoi Y, Yandell MA, Kunin A, Takayanagi T, Neumark DM. Electron accommodation dynamics in the DNA base thymine. J Chem Phys 2016; 143:024312. [PMID: 26178110 DOI: 10.1063/1.4923343] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The dynamics of electron attachment to the DNA base thymine are investigated using femtosecond time-resolved photoelectron imaging of the gas phase iodide-thymine (I(-)T) complex. An ultraviolet pump pulse ejects an electron from the iodide and prepares an iodine-thymine temporary negative ion that is photodetached with a near-IR probe pulse. The resulting photoelectrons are analyzed with velocity-map imaging. At excitation energies ranging from -120 meV to +90 meV with respect to the vertical detachment energy (VDE) of 4.05 eV for I(-)T, both the dipole-bound and valence-bound negative ions of thymine are observed. A slightly longer rise time for the valence-bound state than the dipole-bound state suggests that some of the dipole-bound anions convert to valence-bound species. No evidence is seen for a dipole-bound anion of thymine at higher excitation energies, in the range of 0.6 eV above the I(-)T VDE, which suggests that if the dipole-bound anion acts as a "doorway" to the valence-bound anion, it only does so at excitation energies near the VDE of the complex.
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Affiliation(s)
- Sarah B King
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Anne B Stephansen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 København Ø, Denmark
| | - Yuki Yokoi
- Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Margaret A Yandell
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Alice Kunin
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Toshiyuki Takayanagi
- Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan
| | - Daniel M Neumark
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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23
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Bull JN, West CW, Verlet JRR. Ultrafast dynamics of formation and autodetachment of a dipole-bound state in an open-shell π-stacked dimer anion. Chem Sci 2016; 7:5352-5361. [PMID: 30155188 PMCID: PMC6020752 DOI: 10.1039/c6sc01062h] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/23/2016] [Indexed: 12/15/2022] Open
Abstract
Isolated π-stacked dimer radical anions present the simplest model of an excess electron in a π-stacked environment. Here, frequency-, angle-, and time-resolved photoelectron imaging together with electronic structure calculations have been used to characterise the π-stacked coenzyme Q0 dimer radical anion and its exited state dynamics. In the ground electronic state, the excess electron is localised on one monomer with a planar para-quinone ring, which is solvated by the second monomer in which carbonyl groups are bent out of the para-quinone ring plane. Through the π-stacking interaction, the dimer anion exhibits a number of charge-transfer (intermolecular) valence-localised resonances situated in the detachment continuum that undergo efficient internal conversion to a cluster dipole-bound state (DBS) on a ∼60 fs timescale. In turn, the DBS undergoes vibration-mediated autodetachment on a 2.0 ± 0.2 ps timescale. Experimental vibrational structure and supporting calculations assign the intermolecular dynamics to be facilitated by vibrational wagging modes of the carbonyl groups on the non-planar monomer. At photon energies ∼0.6-1.0 eV above the detachment threshold, a competition between photoexcitation of an intermolecular resonance leading to the DBS, and photoexcitation of an intramolecular resonance leading to monomer-like dynamics further illustrates the π-stacking specific dynamics. Overall, this study provides the first direct observation of both internal conversion of resonances into a DBS, and characterisation of a vibration-mediated autodetachment in real-time.
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Affiliation(s)
- James N Bull
- Department of Chemistry , Durham University , South Road , Durham DH1 3LE , UK .
| | - Christopher W West
- Department of Chemistry , Durham University , South Road , Durham DH1 3LE , UK .
| | - Jan R R Verlet
- Department of Chemistry , Durham University , South Road , Durham DH1 3LE , UK .
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24
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Carpenter BK, Harvey JN, Orr-Ewing AJ. The Study of Reactive Intermediates in Condensed Phases. J Am Chem Soc 2016; 138:4695-705. [DOI: 10.1021/jacs.6b01761] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Barry K. Carpenter
- School
of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, U.K
| | - Jeremy N. Harvey
- Department
of Chemistry, KU Leuven, Celestijnen Laan 200F, B-3001 Heverlee, Belgium
| | - Andrew J. Orr-Ewing
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
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25
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Kunin A, Li WL, Neumark DM. Time-resolved photoelectron imaging of iodide–nitromethane (I−·CH3NO2) photodissociation dynamics. Phys Chem Chem Phys 2016; 18:33226-33232. [DOI: 10.1039/c6cp06646a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dissociation to reform iodide was found to be non-statistical and is predicted to be limited by intramolecular vibrational energy redistribution.
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Affiliation(s)
- Alice Kunin
- Department of Chemistry
- University of California
- Berkeley
- USA
| | - Wei-Li Li
- Department of Chemistry
- University of California
- Berkeley
- USA
| | - Daniel M. Neumark
- Department of Chemistry
- University of California
- Berkeley
- USA
- Chemical Sciences Division
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26
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Sen A, Matthews EM, Hou GL, Wang XB, Dessent CEH. Photoelectron spectroscopy of hexachloroplatinate-nucleobase complexes: Nucleobase excited state decay observed via delayed electron emission. J Chem Phys 2015; 143:184307. [DOI: 10.1063/1.4935171] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Ananya Sen
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Edward M. Matthews
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Gao-Lei Hou
- Physical Sciences Division, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352, USA
| | - Xue-Bin Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352, USA
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27
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Harvey AJA, Yoshikawa N, Wang JG, Dessent CEH. Communication: Evidence for dipole-bound excited states in gas-phase I− ⋅ MI (M = Na, K, Cs) anionic salt microclusters. J Chem Phys 2015; 143:101103. [DOI: 10.1063/1.4930919] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Andrew J. A. Harvey
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Naruo Yoshikawa
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Jin-Guo Wang
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
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28
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Dawley MM, Tanzer K, Carmichael I, Denifl S, Ptasińska S. Dissociative electron attachment to the gas-phase nucleobase hypoxanthine. J Chem Phys 2015; 142:215101. [DOI: 10.1063/1.4921388] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- M. Michele Dawley
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Katrin Tanzer
- Institut für Ionenphysik und Angewandte Physik, and Center for Molecular Biosciences Innsbruck (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Ian Carmichael
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, and Center for Molecular Biosciences Innsbruck (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Sylwia Ptasińska
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
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