1
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Nimmrich A, Panman MR, Berntsson O, Biasin E, Niebling S, Petersson J, Hoernke M, Björling A, Gustavsson E, van Driel TB, Dohn AO, Laursen M, Zederkof DB, Tono K, Katayama T, Owada S, Nielsen MM, Davidsson J, Uhlig J, Hub JS, Haldrup K, Westenhoff S. Solvent-Dependent Structural Dynamics in the Ultrafast Photodissociation Reaction of Triiodide Observed with Time-Resolved X-ray Solution Scattering. J Am Chem Soc 2023. [PMID: 37163700 PMCID: PMC10375522 DOI: 10.1021/jacs.3c00484] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Resolving the structural dynamics of bond breaking, bond formation, and solvation is required for a deeper understanding of solution-phase chemical reactions. In this work, we investigate the photodissociation of triiodide in four solvents using femtosecond time-resolved X-ray solution scattering following 400 nm photoexcitation. Structural analysis of the scattering data resolves the solvent-dependent structural evolution during the bond cleavage, internal rearrangements, solvent-cage escape, and bond reformation in real time. The nature and structure of the reaction intermediates during the recombination are determined, elucidating the full mechanism of photodissociation and recombination on ultrafast time scales. We resolve the structure of the precursor state for recombination as a geminate pair. Further, we determine the size of the solvent cages from the refined structures of the radical pair. The observed structural dynamics present a comprehensive picture of the solvent influence on structure and dynamics of dissociation reactions.
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Affiliation(s)
- Amke Nimmrich
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Matthijs R Panman
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Oskar Berntsson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Elisa Biasin
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Stephan Niebling
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Jonas Petersson
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, 75120 Uppsala, Sweden
| | - Maria Hoernke
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Alexander Björling
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Emil Gustavsson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
| | - Tim B van Driel
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Asmus O Dohn
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark
- Faculty of Physical Sciences, University of Iceland, VR-III, 107 Reykjavík, Iceland
| | - Mads Laursen
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Diana B Zederkof
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Tetsuo Katayama
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Shigeki Owada
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Martin M Nielsen
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Jan Davidsson
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, 75120 Uppsala, Sweden
| | - Jens Uhlig
- Department of Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden
| | - Jochen S Hub
- Georg-August-Universität Göttingen, Institute for Microbiology and Genetics, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
| | - Kristoffer Haldrup
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Sebastian Westenhoff
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, 40530 Gothenburg, Sweden
- Department of Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden
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2
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Ahsan MS, Kochetov V, Hein D, Bokarev SI, Wilkinson I. Probing the molecular structure of aqueous triiodide via X-ray photoelectron spectroscopy and correlated electron phenomena. Phys Chem Chem Phys 2022; 24:15540-15555. [PMID: 35713286 DOI: 10.1039/d1cp05840a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Liquid-microjet-based X-ray photoelectron spectroscopy was applied to aqueous triiodide solutions, I3-(aq.), to investigate the anion's valence- and core-level electronic structure, ionization dynamics, associated electron-correlation effects, and nuclear geometric structure. The roles of multi-active-electron (shake-up) ionization processes - with noted sensitivity to the solute geometric structure - were investigated through I3-(aq.) solution valence, I 4d, and I 3d core-level measurements. The experimental spectra were interpreted with the aid of simulated photoelectron spectra, built upon multi-reference ab initio electronic structure calculations associated with different I3-(aq.) molecular geometries. A comparison of the single-to-multi-active-electron ionization signal ratios extracted from the experimental and theoretical core-level photoemission spectra suggests that the ground state of the solute adopts a near-linear average geometry in aqueous solutions. This contrasts with the interpretation of time-resolved X-ray solution scattering studies, but is found to be fully consistent with the rest of the solution-phase I3-(aq.) literature. Comparing the results of low- and high-photon-energy photoemission measurements, we further suggest that the aqueous anion adopts a more asymmetric geometry at the aqueous-solution-gas interface than in the aqueous bulk.
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Affiliation(s)
- Md Sabbir Ahsan
- Department of Locally-Sensitive and Time-Resolved Spectroscopy, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany. .,Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Vladislav Kochetov
- Institut für Physik, Universität Rostock, Albert Einstein Str. 23-24, D-18059 Rostock, Germany
| | - Dennis Hein
- Operando Interfacial Photochemistry, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-platz. 1, D-14109 Berlin, Germany.,Department of Physics, Humboldt-Universität zu Berlin, Newtonstrasse 15, D-12489 Berlin, Germany
| | - Sergey I Bokarev
- Institut für Physik, Universität Rostock, Albert Einstein Str. 23-24, D-18059 Rostock, Germany
| | - Iain Wilkinson
- Department of Locally-Sensitive and Time-Resolved Spectroscopy, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany.
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3
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Ledbetter K, Biasin E, Nunes JPF, Centurion M, Gaffney KJ, Kozina M, Lin MF, Shen X, Yang J, Wang XJ, Wolf TJA, Cordones AA. Photodissociation of aqueous I 3 - observed with liquid-phase ultrafast mega-electron-volt electron diffraction. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2020; 7:064901. [PMID: 33415183 PMCID: PMC7771998 DOI: 10.1063/4.0000051] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 11/22/2020] [Indexed: 05/26/2023]
Abstract
Developing femtosecond resolution methods for directly observing structural dynamics is critical to understanding complex photochemical reaction mechanisms in solution. We have used two recent developments, ultrafast mega-electron-volt electron sources and vacuum compatible sub-micron thick liquid sheet jets, to enable liquid-phase ultrafast electron diffraction (LUED). We have demonstrated the viability of LUED by investigating the photodissociation of tri-iodide initiated with a 400 nm laser pulse. This has enabled the average speed of the bond expansion to be measured during the first 750 fs of dissociation and the geminate recombination to be directly captured on the picosecond time scale.
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Affiliation(s)
| | - E. Biasin
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - J. P. F. Nunes
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
| | - M. Centurion
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
| | - K. J. Gaffney
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - M. Kozina
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - M.-F. Lin
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - X. Shen
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | | | - X. J. Wang
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - T. J. A. Wolf
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - A. A. Cordones
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
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4
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Gregory J, Verlet JRR, Bull JN. Spectroscopic characterisation of radical polyinterhalogen molecules. Phys Chem Chem Phys 2020; 22:8284-8288. [PMID: 32270847 DOI: 10.1039/d0cp01311k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spectroscopic characterisations of the radical polyinterhalogen molecules IF2 and I2F are reported using anion photoelectron spectroscopy. The corresponding parent anions, IF2- and I2F-, are common products formed in hard Ar-CF3I plasmas and are relevant in the semiconductor manufacture industry. The I2F- species, which is present as the [I-I-F]- isomer, is a "non-classical" polyinterhalogen.
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Affiliation(s)
- Joe Gregory
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
| | - Jan R R Verlet
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, UK
| | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK.
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5
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Gibbard JA, Continetti RE. Photoelectron-photofragment coincidence studies of I 3- using an electrospray ionization source and a linear accelerator. Faraday Discuss 2019; 217:203-219. [PMID: 31012884 DOI: 10.1039/c8fd00216a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoelectron-photofragment coincidence (PPC) spectroscopy is used to examine the dissociative photodetachment (DPD) of I3-. The high beam energy PPC spectrometer for complex anions couples an electrospray ionization source, a hexapole accumulation ion trap and a linear accelerator to produce fast beams of I3- (M = 381 amu) anions, the heaviest system studied to date. Following photodetachment, the photoelectron and up to three photofragments are recorded in coincidence yielding a kinematically complete picture of the DPD dynamics at beam energies of 11 keV and 21 keV. Photodetachment leads to the production of stable I3, two-body DPD, as well as evidence for two- and three-body photodissociation. DPD is found to occur predominantly via the first excited A state, with some contributions from highly excited vibrational levels in the neutral ground state. With the ions thermalized to 298 K in the hexapole trap, there are significant contributions from vibrational hot bands. Three-body photodissociation at 4.66 eV is found to occur preferentially via a charge-symmetric process to form I + I- + I. In the future this method will be applied to other polyatomic systems with a large molecular mass, including multiply charged anions and complex clusters, in concert with a cryogenically cooled hexapole trap to reduce thermal effects.
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Affiliation(s)
- J A Gibbard
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Dr, La Jolla, Ca 92093-0340, USA.
| | - R E Continetti
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Dr, La Jolla, Ca 92093-0340, USA.
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6
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Shee A, Saue T, Visscher L, Severo Pereira Gomes A. Equation-of-motion coupled-cluster theory based on the 4-component Dirac–Coulomb(–Gaunt) Hamiltonian. Energies for single electron detachment, attachment, and electronically excited states. J Chem Phys 2018; 149:174113. [DOI: 10.1063/1.5053846] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Avijit Shee
- Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, Michigan 48109-1055, USA
- Université de Lille, CNRS, UMR 8523—PhLAM—Physique des Lasers, Atomes et Molécules, F-59000 Lille, France
| | - Trond Saue
- Laboratoire de Chimie et Physique Quantiques, UMR 5626 CNRS—Université Toulouse III–Paul Sabatier, 118 Route de Narbonne, F-31062 Toulouse, France
| | - Lucas Visscher
- Division of Theoretical Chemistry, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - André Severo Pereira Gomes
- Université de Lille, CNRS, UMR 8523—PhLAM—Physique des Lasers, Atomes et Molécules, F-59000 Lille, France
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7
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Triiodide and mixed tri-halide anions from negative ion electrospray ionization of alkali halide solutions. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.07.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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8
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Schott S, Ress L, Hrušák J, Nuernberger P, Brixner T. Identification of photofragmentation patterns in trihalide anions by global analysis of vibrational wavepacket dynamics in broadband transient absorption data. Phys Chem Chem Phys 2016; 18:33287-33302. [DOI: 10.1039/c6cp06729h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Photodissociation pathways of a trihalide series are systematically investigated by globally fitting vibrational wavepacket signals in broadband transient absorption spectra.
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Affiliation(s)
- Sebastian Schott
- Institut für Physikalische und Theoretische Chemie
- Universität Würzburg
- D-97074 Würzburg
- Germany
| | - Lea Ress
- Institut für Physikalische und Theoretische Chemie
- Universität Würzburg
- D-97074 Würzburg
- Germany
| | - Jan Hrušák
- J. Heyrovský Institute of Physical Chemistry v.v.i
- Academy of Sciences of the Czech Republic
- 182 23 Praha 8
- Czech Republic
| | | | - Tobias Brixner
- Institut für Physikalische und Theoretische Chemie
- Universität Würzburg
- D-97074 Würzburg
- Germany
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9
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Hwan Kim K, Kim J, Hyuk Lee J, Ihee H. Topical Review: Molecular reaction and solvation visualized by time-resolved X-ray solution scattering: Structure, dynamics, and their solvent dependence. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2014; 1:011301. [PMID: 26798770 PMCID: PMC4711596 DOI: 10.1063/1.4865234] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 01/17/2014] [Indexed: 05/16/2023]
Abstract
Time-resolved X-ray solution scattering is sensitive to global molecular structure and can track the dynamics of chemical reactions. In this article, we review our recent studies on triiodide ion (I3 (-)) and molecular iodine (I2) in solution. For I3 (-), we elucidated the excitation wavelength-dependent photochemistry and the solvent-dependent ground-state structure. For I2, by combining time-slicing scheme and deconvolution data analysis, we mapped out the progression of geminate recombination and the associated structural change in the solvent cage. With the aid of X-ray free electron lasers, even clearer observation of ultrafast chemical events will be made possible in the near future.
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Affiliation(s)
| | - Jeongho Kim
- Department of Chemistry, Inha University , Incheon 402-751, South Korea
| | - Jae Hyuk Lee
- Department of Chemistry, KAIST , Daejeon 305-701, South Korea
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10
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Kim KH, Ki H, Oang KY, Nozawa S, Sato T, Kim J, Kim TK, Kim J, Adachi SI, Ihee H. Global reaction pathways in the photodissociation of I3 (-) ions in solution at 267 and 400 nm studied by picosecond X-ray liquidography. Chemphyschem 2013; 14:3687-97. [PMID: 24115265 DOI: 10.1002/cphc.201300713] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Indexed: 11/08/2022]
Abstract
The mechanism of a photochemical reaction involves the formation and dissociation of various short-lived species on ultrafast timescales and therefore its characterization requires detailed structural information on the transient species. By making use of a structurally sensitive X-ray probe, time-resolved X-ray liquidography (TRXL) can directly elucidate the structures of reacting molecules in the solution phase and thus determine the comprehensive reaction mechanism with high accuracy. In this work, by performing TRXL measurements at two different wavelengths (400 and 267 nm), the reaction mechanism of I3 (-) photolysis, which changes subtly depending on the excitation wavelength, is elucidated. Upon 400 nm photoexcitation, the I3 (-) ion dissociates into I2 (-) and I. By contrast, upon 267 nm photoexcitation, the I3 (-) ion undergoes both two-body dissociation (I2 (-) +I) and three-body dissociation (I(-) +2I) with 7:3 molar ratio. At both excitation wavelengths, all the transient species ultimately disappear in 80 ns by recombining to form the I3 (-) ion nongeminately. In addition to the reaction dynamics of solute species, the results reveal the transient structure of the solute/solvent cage and the changes in solvent density and temperature as a function of time.
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Affiliation(s)
- Kyung Hwan Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701 (Republic of Korea), Fax: (+82) 42-350-2810; Department of Chemistry, KAIST, Daejeon 305-701 (Republic of Korea)
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11
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Kim KH, Lee JH, Kim J, Nozawa S, Sato T, Tomita A, Ichiyanagi K, Ki H, Kim J, Adachi SI, Ihee H. Solvent-dependent molecular structure of ionic species directly measured by ultrafast x-ray solution scattering. PHYSICAL REVIEW LETTERS 2013; 110:165505. [PMID: 23679619 DOI: 10.1103/physrevlett.110.165505] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Indexed: 05/28/2023]
Abstract
Ionic species often play important roles in chemical reactions occurring in water and other solvents, but it has been elusive to determine the solvent-dependent molecular structure with atomic resolution. The triiodide ion has a molecular structure that sensitively changes depending on the type of solvent and its symmetry can be broken by strong solute-solvent interaction. Here, by applying pump-probe x-ray solution scattering, we characterize the exact molecular structure of I(3)(-) ion in water, methanol, and acetonitrile with subangstrom accuracy. The data reveal that I(3)(-) ion has an asymmetric and bent structure in water. In contrast, the ion keeps its symmetry in acetonitrile, while the symmetry breaking occurs to a lesser extent in methanol than in water. The symmetry breaking of I(3)(-) ion is reproduced by density functional theory calculations using 34 explicit water molecules, confirming that the origin of the symmetry breaking is the hydrogen-bonding interaction between the solute and solvent molecules.
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Affiliation(s)
- Kyung Hwan Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701, Republic of Korea
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12
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Crider PE, Harrison AW, Neumark DM. Two- and three-body photodissociation dynamics of diiodobromide (I2Br−) anion. J Chem Phys 2011; 134:134306. [DOI: 10.1063/1.3571474] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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13
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Gomes ASP, Visscher L, Bolvin H, Saue T, Knecht S, Fleig T, Eliav E. The electronic structure of the triiodide ion from relativistic correlated calculations: A comparison of different methodologies. J Chem Phys 2010; 133:064305. [DOI: 10.1063/1.3474571] [Citation(s) in RCA: 25] [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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14
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Nakanishi R, Saitou N, Ohno T, Kowashi S, Yabushita S, Nagata T. Photodissociation of gas-phase I3−: Comprehensive understanding of nonadiabatic dissociation dynamics. J Chem Phys 2007; 126:204311. [PMID: 17552766 DOI: 10.1063/1.2736691] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Photodissociation of the gas-phase tri-iodide anion, I3-, was investigated using photofragment time of flight (TOF) mass spectrometry combined with the core extraction method. An analysis of the TOF profiles provided the kinetic energy and angular distributions of photofragment ions and photoneutrals, from which the photoproduct branching fractions were determined in the excitation energy range of 3.26-4.27 eV. The measurement has revealed that (1) in the entire energy range investigated, three-body dissociation occurs preferentially as the "charge-asymmetric" process I-(1S)+I(2P3/2)+I(2P3/2) with the yield of approximately 30%-40%, where the excess charge is localized on the end atoms of the dissociating I3-, and that (2) two-body dissociation via the 3Piu(0u+)<--1Sigmag+(0g+) excitation proceeds as I-(1S)+I2(X 1Sigmag+)/I2(A 3Pi1u) or I(2P3/2)+I2-(X 2Sigmau+) with the yield of approximately 60%, while that via the 1Sigmau+(0u+)<--1Sigmag+(0g+) excitation alternatively as I*(2P1/2)+I2-(X 2Sigmau+) or I-(1S)+I2(B 3Piu) with the yield of approximately 60%. Ab initio calculations including spin-orbit configuration interactions were also performed to gain precise information on the potential energy surfaces relevant to the I3- photodissociation. The calculations have shown the presence of conical intersections and avoided crossings located along the symmetric stretch coordinate near the ground-state equilibrium geometry of I3-, which play key roles for the two-body and the three-body product branching. The nonadiabatic nature of the I3- photodissociation dynamics is discussed by combining the experimental findings and the ab initio results.
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Affiliation(s)
- Ryuzo Nakanishi
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan
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15
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Hoops AA, Gascooke JR, Faulhaber AE, Kautzman KE, Neumark DM. Two- and three-body photodissociation of gas phase I3−. J Chem Phys 2004; 120:7901-9. [PMID: 15267705 DOI: 10.1063/1.1691017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The photodissociation dynamics of I3- from 390 to 290 nm (3.18 to 4.28 eV) have been investigated using fast beam photofragment translational spectroscopy in which the products are detected and analyzed with coincidence imaging. At photon energies < or = 3.87 eV, two-body dissociation that generates I- + I2(A 3Pi1) and vibrationally excited I2- (X 2Sigmau+) + I(2P(3/2)) is observed, while at energies > or = 3.87 eV, I*(2P(1/2)) + I2- (X 2Sigmau+) is the primary two-body dissociation channel. In addition, three-body dissociation yielding I- +2I(2P(3/2)) photofragments is seen throughout the energy range probed; this is the dominant channel at all but the lowest photon energy. Analysis of the three-body dissociation events indicates that this channel results primarily from a synchronous concerted decay mechanism.
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Affiliation(s)
- Alexandra A Hoops
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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16
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Mabbs R, Pichugin K, Surber E, Sanov A. Time-resolved electron detachment imaging of the I[sup −] channel in I[sub 2]Br[sup −] photodissociation. J Chem Phys 2004; 121:265-72. [PMID: 15260544 DOI: 10.1063/1.1756869] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The evolution of the I(-) channel in I(2)Br(-) photodissociation is examined using time-resolved negative-ion photoelectron imaging spectroscopy. The 388 nm photodetachment images obtained at variable delays following 388 nm excitation reveal the transformation of the excess electron from that belonging to an excited trihalide anion to that occupying an atomic orbital localized on the I(-) fragment. With increasing pump-probe delay, the corresponding photoelectron band narrows on a approximately 300 fs time scale. This trend is attributed to the localization of the excess-electron wave function on the atomic-anion fragment and the establishment of the fragment's electronic identity. The corresponding band position drifts towards larger electron kinetic energies on a significantly longer, approximately 1 ps, time scale. The gradual spectral shift is attributed to exit-channel interactions affecting the photodetachment energetics, as well as the photoelectron anisotropy. The time-resolved angular distributions are analyzed and found consistent with the formation of the asymptotic I(-) fragment.
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Affiliation(s)
- Richard Mabbs
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA
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