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Takatsuka K. Quantum Chaos in the Dynamics of Molecules. ENTROPY (BASEL, SWITZERLAND) 2022; 25:63. [PMID: 36673204 PMCID: PMC9857761 DOI: 10.3390/e25010063] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/22/2022] [Accepted: 12/22/2022] [Indexed: 06/17/2023]
Abstract
Quantum chaos is reviewed from the viewpoint of "what is molecule?", particularly placing emphasis on their dynamics. Molecules are composed of heavy nuclei and light electrons, and thereby the very basic molecular theory due to Born and Oppenheimer gives a view that quantum electronic states provide potential functions working on nuclei, which in turn are often treated classically or semiclassically. Therefore, the classic study of chaos in molecular science began with those nuclear dynamics particularly about the vibrational energy randomization within a molecule. Statistical laws in probabilities and rates of chemical reactions even for small molecules of several atoms are among the chemical phenomena requiring the notion of chaos. Particularly the dynamics behind unimolecular decomposition are referred to as Intra-molecular Vibrational energy Redistribution (IVR). Semiclassical mechanics is also one of the main research fields of quantum chaos. We herein demonstrate chaos that appears only in semiclassical and full quantum dynamics. A fundamental phenomenon possibly giving birth to quantum chaos is "bifurcation and merging" of quantum wavepackets, rather than "stretching and folding" of the baker's transformation and the horseshoe map as a geometrical foundation of classical chaos. Such wavepacket bifurcation and merging are indeed experimentally measurable as we showed before in the series of studies on real-time probing of nonadiabatic chemical reactions. After tracking these aspects of molecular chaos, we will explore quantum chaos found in nonadiabatic electron wavepacket dynamics, which emerges in the realm far beyond the Born-Oppenheimer paradigm. In this class of chaos, we propose a notion of Intra-molecular Nonadiabatic Electronic Energy Redistribution (INEER), which is a consequence of the chaotic fluxes of electrons and energy within a molecule.
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Affiliation(s)
- Kazuo Takatsuka
- Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan
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2
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A localized view on molecular dissociation via electron-ion partial covariance. Commun Chem 2022; 5:42. [PMID: 36697752 PMCID: PMC9814695 DOI: 10.1038/s42004-022-00656-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/21/2022] [Indexed: 02/01/2023] Open
Abstract
Inner-shell photoelectron spectroscopy provides an element-specific probe of molecular structure, as core-electron binding energies are sensitive to the chemical environment. Short-wavelength femtosecond light sources, such as Free-Electron Lasers (FELs), even enable time-resolved site-specific investigations of molecular photochemistry. Here, we study the ultraviolet photodissociation of the prototypical chiral molecule 1-iodo-2-methylbutane, probed by extreme-ultraviolet (XUV) pulses from the Free-electron LASer in Hamburg (FLASH) through the ultrafast evolution of the iodine 4d binding energy. Methodologically, we employ electron-ion partial covariance imaging as a technique to isolate otherwise elusive features in a two-dimensional photoelectron spectrum arising from different photofragmentation pathways. The experimental and theoretical results for the time-resolved electron spectra of the 4d3/2 and 4d5/2 atomic and molecular levels that are disentangled by this method provide a key step towards studying structural and chemical changes from a specific spectator site.
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3
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Rösch D, Almeida R, Sztáray B, Osborn DL. High-Resolution Double Velocity Map Imaging Photoelectron Photoion Coincidence Spectrometer for Gas-Phase Reaction Kinetics. J Phys Chem A 2022; 126:1761-1774. [PMID: 35258948 DOI: 10.1021/acs.jpca.1c10293] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We present a new photoelectron photoion coincidence (PEPICO) spectrometer that combines high mass resolution of cations with independently adjustable velocity map imaging of both cations and electrons. We photoionize atoms and molecules using fixed-frequency vacuum ultraviolet radiation. Mass-resolved photoelectron spectra associated with each cation's mass-to-charge ratio can be obtained by inversion of the photoelectron image. The mass-resolved photoelectron spectra enable kinetic time-resolved probing of chemical reactions with isomeric resolution using fixed-frequency radiation sources amenable to small laboratory settings. The instrument accommodates a variety of sample delivery sources to explore a broad range of physical chemistry. To demonstrate the time-resolved capabilities of the instrument, we study the 193 nm photodissociation of SO2 via the C̃(1B2) ← X̃(1A1) transition. In addition to the well-documented O(3Pj) + SO(3Σ-) channel, we observe direct evidence for a small yield of S(3Pj) + O2(3Σg-) as a primary photodissociation product channel, which may impact sulfur mass-independent fractionation chemistry.
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Affiliation(s)
- Daniel Rösch
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States
| | - Raybel Almeida
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States
| | - Bálint Sztáray
- Department of Chemistry, University of the Pacific, Stockton, California 95211, United States
| | - David L Osborn
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551-0969, United States.,Department of Chemical Engineering, University of California, Davis, Davis, California 95616, United States
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4
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Schuurman MS, Blanchet V. Time-resolved photoelectron spectroscopy: the continuing evolution of a mature technique. Phys Chem Chem Phys 2022; 24:20012-20024. [PMID: 35297909 DOI: 10.1039/d1cp05885a] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Time-resolved photoelectron spectroscopy (TRPES) has become one of the most widespread techniques for probing nonadiabatic dynamics in the excited electronic states of molecules. Furthermore, the complementary development of ab initio approaches for the simulation of TRPES signals has enabled the interpretation of these transient spectra in terms of underlying coupled electronic-nuclear dynamics. In this perspective, we discuss the current state-of-the-art approaches, including efforts to push femtosecond pulses into vacuum ultraviolet and soft X-ray regimes as well as the utilization of novel polarizations to use time-resolved optical activity as a probe of nonadiabatic dynamics. We close this perspective with a forward-looking prospectus on the new areas of application for this technique.
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Affiliation(s)
- Michael S Schuurman
- National Research Council of Canada, 100 Sussex Dr, Ottawa, ON, K1N 6B9, Canada.,Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie Dr, Ottawa, ON, Canada.
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Bruder L, Wittenbecher L, Kolesnichenko PV, Zigmantas D. Generation and compression of 10-fs deep ultraviolet pulses at high repetition rate using standard optics. OPTICS EXPRESS 2021; 29:25593-25604. [PMID: 34614887 DOI: 10.1364/oe.425053] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 06/16/2021] [Indexed: 06/13/2023]
Abstract
The generation and characterization of ultrashort laser pulses in the deep ultraviolet spectral region is challenging, especially at high pulse repetition rates and low pulse energies. Here, we combine achromatic second harmonic generation and adaptive pulse compression for the efficient generation of sub-10 fs deep ultraviolet laser pulses at a laser repetition rate of 200 kHz. Furthermore, we simplify the pulse compression scheme and reach pulse durations of ≈10 fs without the use of adaptive optics. We demonstrate straight-forward tuning from 250 to 320 nm, broad pulse spectra of up to 63 nm width, excellent stability and a high robustness against misalignment. These features make the approach appealing for numerous spectroscopy and imaging applications.
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6
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Three-dimensional covariance-map imaging of molecular structure and dynamics on the ultrafast timescale. Commun Chem 2020; 3:72. [PMID: 36703470 PMCID: PMC9814411 DOI: 10.1038/s42004-020-0320-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 05/15/2020] [Indexed: 01/29/2023] Open
Abstract
Ultrafast laser pump-probe methods allow chemical reactions to be followed in real time, and have provided unprecedented insight into fundamental aspects of chemical reactivity. While evolution of the electronic structure of the system under study is evident from changes in the observed spectral signatures, information on rearrangement of the nuclear framework is generally obtained indirectly. Disentangling contributions to the signal arising from competing photochemical pathways can also be challenging. Here we introduce the new technique of three-dimensional covariance-map Coulomb explosion imaging, which has the potential to provide complete three-dimensional information on molecular structure and dynamics as they evolve in real time during a gas-phase chemical reaction. We present first proof-of-concept data from recent measurements on CF3I. Our approach allows the contributions from competing fragmentation pathways to be isolated and characterised unambiguously, and is a promising route to enabling the recording of 'molecular movies' for a wide variety of gas-phase chemical processes.
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7
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Michiels R, LaForge AC, Bohlen M, Callegari C, Clark A, von Conta A, Coreno M, Di Fraia M, Drabbels M, Finetti P, Huppert M, Oliver V, Plekan O, Prince KC, Stranges S, Svoboda V, Wörner HJ, Stienkemeier F. Time-resolved formation of excited atomic and molecular states in XUV-induced nanoplasmas in ammonia clusters. Phys Chem Chem Phys 2020; 22:7828-7834. [PMID: 32248221 DOI: 10.1039/d0cp00669f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High intensity XUV radiation from a free-electron laser (FEL) was used to create a nanoplasma inside ammonia clusters with the intent of studying the resulting electron-ion interactions and their interplay with plasma evolution. In a plasma-like state, electrons with kinetic energy lower than the local collective Coulomb potential of the positive ionic core are trapped in the cluster and take part in secondary processes (e.g. electron-impact excitation/ionization and electron-ion recombination) which lead to subsequent excited and neutral molecular fragmentation. Using a time-delayed UV laser, the dynamics of the excited atomic and molecular states are probed from -0.1 ps to 18 ps. We identify three different phases of molecular fragmentation that are clearly distinguished by the effect of the probe laser on the ionic and electronic yield. We propose a simple model to rationalize our data and further identify two separate channels leading to the formation of excited hydrogen.
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Affiliation(s)
- Rupert Michiels
- Institute of Physics, University of Freiburg, 79104 Freiburg, Germany.
| | - Aaron C LaForge
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Matthias Bohlen
- Institute of Physics, University of Freiburg, 79104 Freiburg, Germany.
| | - Carlo Callegari
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste, Italy
| | - Andrew Clark
- Laboratory of Molecular Nanodynamics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Aaron von Conta
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
| | - Marcello Coreno
- ISM-CNR, Istituto di Struttura della Materia, LD2 Unit, 34149 Trieste, Italy
| | - Michele Di Fraia
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste, Italy
| | - Marcel Drabbels
- Laboratory of Molecular Nanodynamics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Paola Finetti
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste, Italy
| | - Martin Huppert
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
| | - Veronica Oliver
- Laboratory of Molecular Nanodynamics, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Oksana Plekan
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste, Italy
| | - Kevin C Prince
- Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste, Italy
| | - Stefano Stranges
- Department of Chemistry and Drug Technologies, University Sapienza, 00185 Rome, Italy, and Tasc IOM-CNR, Basovizza, Trieste, Italy
| | - Vít Svoboda
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
| | - Hans Jakob Wörner
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
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Debrah DA, Stewart GA, Basnayake G, Nomerotski A, Svihra P, Lee SK, Li W. Developing a camera-based 3D momentum imaging system capable of 1 Mhits/s. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:023316. [PMID: 32113393 DOI: 10.1063/1.5138731] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/23/2020] [Indexed: 06/10/2023]
Abstract
A camera-based three-dimensional (3D) imaging system with a superb time-of-flight (TOF) resolution and multi-hit capability was recently developed for electron/ion imaging [Lee et al. J. Chem. Phys. 141, 221101 (2014)]. In this work, we report further improvement of the event rate of the system by adopting an event-driven camera, Tpx3Cam, for detecting the 2D positions of electrons, while a high-speed digitizer provides highly accurate (∼30 ps) TOF information for each event at a rate approaching 1 Mhits/sec.
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Affiliation(s)
- Duke A Debrah
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Gabriel A Stewart
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Gihan Basnayake
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Andrei Nomerotski
- Physics Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Peter Svihra
- Physics Department, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Suk Kyoung Lee
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Wen Li
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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9
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Lehmann CS, Weitzel KM. Coincident measurement of photo-ion circular dichroism and photo-electron circular dichroism. Phys Chem Chem Phys 2020; 22:13707-13712. [DOI: 10.1039/d0cp01376e] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photo-ion circular dichroism (PICD) and photo-electron circular dichroism (PECD) have been measured for the first time simultaneously in a coincidence experiment detecting the chirality of R- and S-Methyloxirane.
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10
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Röder A, Petersen J, Issler K, Fischer I, Mitrić R, Poisson L. Exploring the Excited-State Dynamics of Hydrocarbon Radicals, Biradicals, and Carbenes Using Time-Resolved Photoelectron Spectroscopy and Field-Induced Surface Hopping Simulations. J Phys Chem A 2019; 123:10643-10662. [DOI: 10.1021/acs.jpca.9b06346] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anja Röder
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
- LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France
| | - Jens Petersen
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Kevin Issler
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ingo Fischer
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Roland Mitrić
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Lionel Poisson
- LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France
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11
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Wang QX, Shi DD, Zhang JF, Wang X, Si Y, Gao CB, Fang J, Luo SZ. Channel-resolved ultrafast dissociation dynamics of NO 2 molecules studied via femtosecond time-resolved ion imaging. CHINESE J CHEM PHYS 2019. [DOI: 10.1063/1674-0068/cjcp1807177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Qin-xin Wang
- College of Electrical Engineering, Jilin Engineering Normal University, Changchun 130012, China
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, Changchun 130012, China
| | - Dan-dan Shi
- College of Electrical Engineering, Jilin Engineering Normal University, Changchun 130012, China
| | - Jun-feng Zhang
- College of Electrical Engineering, Jilin Engineering Normal University, Changchun 130012, China
| | - Xue Wang
- College of Electrical Engineering, Jilin Engineering Normal University, Changchun 130012, China
| | - Yu Si
- College of Electrical Engineering, Jilin Engineering Normal University, Changchun 130012, China
| | - Chun-bin Gao
- College of Electrical Engineering, Jilin Engineering Normal University, Changchun 130012, China
| | - Jian Fang
- College of Electrical Engineering, Jilin Engineering Normal University, Changchun 130012, China
| | - Si-zuo Luo
- Institute of Atomic and Molecular Physics and Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy, Jilin University, Changchun 130012, China
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12
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Ablikim U, Bomme C, Osipov T, Xiong H, Obaid R, Bilodeau RC, Kling NG, Dumitriu I, Augustin S, Pathak S, Schnorr K, Kilcoyne D, Berrah N, Rolles D. A coincidence velocity map imaging spectrometer for ions and high-energy electrons to study inner-shell photoionization of gas-phase molecules. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:055103. [PMID: 31153288 DOI: 10.1063/1.5093420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 04/18/2019] [Indexed: 06/09/2023]
Abstract
We report on the design and performance of a double-sided coincidence velocity map imaging spectrometer optimized for electron-ion and ion-ion coincidence experiments studying inner-shell photoionization of gas-phase molecules with soft X-ray synchrotron radiation. The apparatus employs two microchannel plate detectors equipped with delay-line anodes for coincident, time- and position-resolved detection of photoelectrons and Auger electrons with kinetic energies up to 300 eV on one side of the spectrometer and photoions up to 25 eV per unit charge on the opposite side. We demonstrate its capabilities by measuring valence photoelectrons and ion spectra of neon and nitrogen and by studying channel-resolved photoelectron and Auger spectra along with fragment-ion momentum correlations for chlorine 2p inner-shell ionization of cis- and trans-1,2-dichloroethene.
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Affiliation(s)
- Utuq Ablikim
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - Cédric Bomme
- Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg, Germany
| | - Timur Osipov
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Hui Xiong
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Razib Obaid
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - René C Bilodeau
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Nora G Kling
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Ileana Dumitriu
- Hobart and William Smith Colleges, Geneva, New York 14456, USA
| | - Sven Augustin
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - Shashank Pathak
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - Kirsten Schnorr
- Max Planck Institute for Nuclear Physics, 69117 Heidelberg, Germany
| | - David Kilcoyne
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Nora Berrah
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Daniel Rolles
- J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
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13
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Suits AG. Invited Review Article: Photofragment imaging. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:111101. [PMID: 30501356 DOI: 10.1063/1.5045325] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/25/2018] [Indexed: 06/09/2023]
Abstract
Photodissociation studies in molecular beams that employ position-sensitive particle detection to map product recoil velocities emerged thirty years ago and continue to evolve with new laser and detector technologies. These powerful methods allow application of tunable laser detection of single product quantum states, simultaneous measurement of velocity and angular momentum polarization, measurement of joint product state distributions for the detected and undetected products, coincident detection of multiple product channels, and application to radicals and ions as well as closed-shell molecules. These studies have permitted deep investigation of photochemical dynamics for a broad range of systems, revealed new reaction mechanisms, and addressed problems of practical importance in atmospheric, combustion, and interstellar chemistry. This review presents an historical overview, a detailed technical account of the range of methods employed, and selected experimental highlights illustrating the capabilities of the method.
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Affiliation(s)
- Arthur G Suits
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
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14
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von Conta A, Tehlar A, Schletter A, Arasaki Y, Takatsuka K, Wörner HJ. Conical-intersection dynamics and ground-state chemistry probed by extreme-ultraviolet time-resolved photoelectron spectroscopy. Nat Commun 2018; 9:3162. [PMID: 30089780 PMCID: PMC6082858 DOI: 10.1038/s41467-018-05292-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 06/15/2018] [Indexed: 11/09/2022] Open
Abstract
Time-resolved photoelectron spectroscopy (TRPES) is a useful approach to elucidate the coupled electronic-nuclear quantum dynamics underlying chemical processes, but has remained limited by the use of low photon energies. Here, we demonstrate the general advantages of XUV-TRPES through an application to NO2, one of the simplest species displaying the complexity of a non-adiabatic photochemical process. The high photon energy enables ionization from the entire geometrical configuration space, giving access to the true dynamics of the system. Specifically, the technique reveals dynamics through a conical intersection, large-amplitude motion and photodissociation in the electronic ground state. XUV-TRPES simultaneously projects the excited-state wave packet onto many final states, offering a multi-dimensional view of the coupled electronic and nuclear dynamics. Our interpretations are supported by ab initio wavepacket calculations on new global potential-energy surfaces. The presented results contribute to establish XUV-TRPES as a powerful technique providing a complete picture of ultrafast chemical dynamics from photoexcitation to the final products.
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Affiliation(s)
- A von Conta
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093, Zurich, Switzerland
| | - A Tehlar
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093, Zurich, Switzerland
| | - A Schletter
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093, Zurich, Switzerland
| | - Y Arasaki
- Fukui Institute for Fundamental Chemistry, Kyoto University, Sakyo-ku, Kyoto, 606-8103, Japan
| | - K Takatsuka
- Fukui Institute for Fundamental Chemistry, Kyoto University, Sakyo-ku, Kyoto, 606-8103, Japan
| | - H J Wörner
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093, Zurich, Switzerland.
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15
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Multidimensional Analysis of Time-Resolved Charged Particle Imaging Experiments. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8081227] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We present a tutorial to realize a multidimensional fitting procedure capable of extracting all the relevant information contained in a sequence of charged particle images acquired as a function of time in femtosecond pump–probe experiments. The images are reproduced using a 3D fitting method, which provides the velocity (or center-of-mass kinetic energy) and angular distributions contained in the images and their time evolution. A detailed example of the method is shown through the analysis of the time-resolved predissociation dynamics of CH3I on the B-band origin (Gitzinger et al., J. Chem. Phys.2010, 133, 234313). We show that the multidimensional approach is essential for the analysis of complex images that contain several overlapping contributions where reduced dimensionality analyses cannot provide a reliable description of the features present in the image sequence. This methodology can be generalized to many types of multidimensional data analysis.
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16
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Zhao A, van Beuzekom M, Bouwens B, Byelov D, Chakaberia I, Cheng C, Maddox E, Nomerotski A, Svihra P, Visser J, Vrba V, Weinacht T. Coincidence velocity map imaging using Tpx3Cam, a time stamping optical camera with 1.5 ns timing resolution. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:113104. [PMID: 29195350 DOI: 10.1063/1.4996888] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We demonstrate a coincidence velocity map imaging apparatus equipped with a novel time-stamping fast optical camera, Tpx3Cam, whose high sensitivity and nanosecond timing resolution allow for simultaneous position and time-of-flight detection. This single detector design is simple, flexible, and capable of highly differential measurements. We show detailed characterization of the camera and its application in strong field ionization experiments.
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Affiliation(s)
- Arthur Zhao
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | | | - Bram Bouwens
- Amsterdam Scientific Instruments, Science Park 105, 1098 XG Amsterdam, The Netherlands
| | - Dmitry Byelov
- Amsterdam Scientific Instruments, Science Park 105, 1098 XG Amsterdam, The Netherlands
| | | | - Chuan Cheng
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - Erik Maddox
- Amsterdam Scientific Instruments, Science Park 105, 1098 XG Amsterdam, The Netherlands
| | | | - Peter Svihra
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, Prague 115 19, Czech Republic
| | - Jan Visser
- Nikhef, Science Park 105, 1098 XG Amsterdam, The Netherlands
| | - Vaclav Vrba
- Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University, Prague 115 19, Czech Republic
| | - Thomas Weinacht
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
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17
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Monitoring non-adiabatic dynamics in CS2 with time- and energy-resolved photoelectron spectra of wavepackets. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.02.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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18
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Poullain SM, Cireasa R, Cornaggia C, Simon M, Marin T, Guillemin R, Houver JC, Lucchese RR, Dowek D. Spectral dependence of photoemission in multiphoton ionization of NO 2 by femtosecond pulses in the 375-430 nm range. Phys Chem Chem Phys 2017; 19:21996-22007. [PMID: 28748241 DOI: 10.1039/c7cp02057k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the multiphoton ionization of NO2 using tunable (430-375 nm) femtosecond pulses and photoelectron-photoion coincidence momentum spectroscopy. In order to understand the complex electronic and nuclear photodynamics at play following absorption of three to five photons, we also report extended photoionization calculations using correlated targets and coupled channels. Exploring the multiphoton dissociative ionization (MPDI) and multiphoton ionization (MPI) processes over such a broad energy range enables us to lend further support to our work carried out around 400 nm of a femtosecond laser [S. Marggi Poullain et al., J. Phys. B: At., Mol. Opt. Phys., 2014, 47, 124024]. Two excitation energy regions are identified and discussed in terms of the proposed reaction pathways, highlighting the significant role of Rydberg states, such as the [R*(6a1)-1, 3pσ] Rydberg state, in the NO2 multiphoton excitation and photoionization. These new results support our previous assumption that different bent and linear geometries of the NO2+(X1Σg) ionic state contribute to the MPDI and MPI, consistent with the reported calculations which reveal an important vibronic coupling characterizing the photoemission. Remarkably, the strong anisotropy of the recoil frame photoelectron angular distribution (RFPAD) previously observed at 400 nm appears as a fingerprint across the whole explored photon energy range.
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Affiliation(s)
- S Marggi Poullain
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
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19
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Chandler DW, Houston PL, Parker DH. Perspective: Advanced particle imaging. J Chem Phys 2017; 147:013601. [PMID: 28688442 PMCID: PMC5648558 DOI: 10.1063/1.4983623] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/18/2017] [Indexed: 11/14/2022] Open
Abstract
Since the first ion imaging experiment [D. W. Chandler and P. L. Houston, J. Chem. Phys. 87, 1445-1447 (1987)], demonstrating the capability of collecting an image of the photofragments from a unimolecular dissociation event and analyzing that image to obtain the three-dimensional velocity distribution of the fragments, the efficacy and breadth of application of the ion imaging technique have continued to improve and grow. With the addition of velocity mapping, ion/electron centroiding, and slice imaging techniques, the versatility and velocity resolution have been unmatched. Recent improvements in molecular beam, laser, sensor, and computer technology are allowing even more advanced particle imaging experiments, and eventually we can expect multi-mass imaging with co-variance and full coincidence capability on a single shot basis with repetition rates in the kilohertz range. This progress should further enable "complete" experiments-the holy grail of molecular dynamics-where all quantum numbers of reactants and products of a bimolecular scattering event are fully determined and even under our control.
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Affiliation(s)
- David W Chandler
- Sandia National Laboratories, Combustion Research Facility, Livermore, California 94550, USA
| | - Paul L Houston
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - David H Parker
- Department of Laser and Molecular Physics, Radboud University of Nijmegen, Nijmegen, Netherlands
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20
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Fan L, Lee SK, Tu YJ, Mignolet B, Couch D, Dorney K, Nguyen Q, Wooldridge L, Murnane M, Remacle F, Schlegel HB, Li W. A new electron-ion coincidence 3D momentum-imaging method and its application in probing strong field dynamics of 2-phenylethyl-N, N-dimethylamine. J Chem Phys 2017; 147:013920. [DOI: 10.1063/1.4981526] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Lin Fan
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Suk Kyoung Lee
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Yi-Jung Tu
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Benoît Mignolet
- Department of Chemistry, B6c, University of Liege, B4000 Liege, Belgium
| | - David Couch
- JILA and University of Colorado at Boulder, Boulder, Colorado 80303, USA
| | - Kevin Dorney
- JILA and University of Colorado at Boulder, Boulder, Colorado 80303, USA
| | - Quynh Nguyen
- JILA and University of Colorado at Boulder, Boulder, Colorado 80303, USA
| | - Laura Wooldridge
- JILA and University of Colorado at Boulder, Boulder, Colorado 80303, USA
| | - Margaret Murnane
- JILA and University of Colorado at Boulder, Boulder, Colorado 80303, USA
| | - Françoise Remacle
- Department of Chemistry, B6c, University of Liege, B4000 Liege, Belgium
| | | | - Wen Li
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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21
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Forbes R, Makhija V, Veyrinas K, Stolow A, Lee JWL, Burt M, Brouard M, Vallance C, Wilkinson I, Lausten R, Hockett P. Time-resolved multi-mass ion imaging: Femtosecond UV-VUV pump-probe spectroscopy with the PImMS camera. J Chem Phys 2017; 147:013911. [DOI: 10.1063/1.4978923] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ruaridh Forbes
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5, Canada
| | - Varun Makhija
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5, Canada
| | - Kévin Veyrinas
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5, Canada
| | - Albert Stolow
- Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5, Canada
- Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
| | - Jason W. L. Lee
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Michael Burt
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Mark Brouard
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Claire Vallance
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Iain Wilkinson
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
- Methods for Material Development, Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Rune Lausten
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
| | - Paul Hockett
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
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22
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Zhao A, Sándor P, Weinacht T. Coincidence velocity map imaging using a single detector. J Chem Phys 2017; 147:013922. [DOI: 10.1063/1.4981917] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Arthur Zhao
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
| | - Péter Sándor
- Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA
| | - Thomas Weinacht
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA
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23
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Okutsu K, Nakashima Y, Yamazaki K, Fujimoto K, Nakano M, Ohshimo K, Misaizu F. Development of a linear-type double reflectron for focused imaging of photofragment ions from mass-selected complex ions. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:053105. [PMID: 28571407 DOI: 10.1063/1.4982706] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
An ion imaging apparatus with a double linear reflectron mass spectrometer has been developed, in order to measure velocity and angular distributions of mass-analyzed fragment ions produced by photodissociation of mass-selected gas phase complex ions. The 1st and the 2nd linear reflectrons were placed facing each other and controlled by high-voltage pulses in order to perform the mass-separation of precursor ions in the 1st reflectron and to observe the focused image of the photofragment ions in the 2nd reflectron. For this purpose, metal meshes were attached on all electrodes in the 1st reflectron, whereas the mesh was attached only on the last electrode in the 2nd reflectron. The performance of this apparatus was evaluated using imaging measurement of Ca+ photofragment ions from photodissociation reaction of Ca+Ar complex ions at 355 nm photoexcitation. The focused ion images were obtained experimentally with the double linear reflectron at the voltages of the reflection electrodes close to the predictions by ion trajectory simulations. The velocity and angular distributions of the produced Ca+ ([Ar] 4p1, 2P3/2) ion were analyzed from the observed images. The binding energy D0 of Ca+Ar in the ground state deduced in the present measurement was consistent with those determined theoretically and by spectroscopic measurements. The anisotropy parameter β of the transition was evaluated for the first time by this instrument.
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Affiliation(s)
- Kenichi Okutsu
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Yuji Nakashima
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Kenichiro Yamazaki
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Keita Fujimoto
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Motoyoshi Nakano
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Keijiro Ohshimo
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Fuminori Misaizu
- Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
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24
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Osborn DL, Hayden CC, Hemberger P, Bodi A, Voronova K, Sztáray B. Breaking through the false coincidence barrier in electron–ion coincidence experiments. J Chem Phys 2016; 145:164202. [DOI: 10.1063/1.4965428] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- David L. Osborn
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA
| | - Carl C. Hayden
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA
| | - Patrick Hemberger
- Laboratory for Femtochemistry and Synchrotron Radiation, Paul Scherrer Institute, Villigen 5232, Switzerland
| | - Andras Bodi
- Laboratory for Femtochemistry and Synchrotron Radiation, Paul Scherrer Institute, Villigen 5232, Switzerland
| | - Krisztina Voronova
- Department of Chemistry, University of the Pacific, Stockton, California 95211, USA
| | - Bálint Sztáray
- Department of Chemistry, University of the Pacific, Stockton, California 95211, USA
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25
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Boesl U, Kartouzian A. Mass-Selective Chiral Analysis. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2016; 9:343-364. [PMID: 27070181 DOI: 10.1146/annurev-anchem-071015-041658] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Three ways of realizing mass-selective chiral analysis are reviewed. The first is based on the formation of diastereomers that are of homo- and hetero- type with respect to the enantiomers of involved chiral molecules. This way is quite well-established with numerous applications. The other two ways are more recent developments, both based on circular dichroism (CD). In one, conventional or nonlinear electronic CD is linked to mass spectrometry (MS) by resonance-enhanced multiphoton ionization. The other is based on CD in the angular distribution of photoelectrons, which is measured in combination with MS via photoion photoelectron coincidence. Among the many important applications of mass-selective chiral analysis, this review focuses on its use as an analytical tool for the development of heterogeneous enantioselective chemical catalysis. There exist other approaches to combine chiral analysis and mass-selective detection, such as chiral chromatography MS, which are not discussed here.
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Affiliation(s)
- Ulrich Boesl
- Department of Chemistry, Technische Universität München, 85747 Garching, Germany; ,
| | - Aras Kartouzian
- Department of Chemistry, Technische Universität München, 85747 Garching, Germany; ,
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26
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Samanta AK, Wang Y, Mancini JS, Bowman JM, Reisler H. Energetics and Predissociation Dynamics of Small Water, HCl, and Mixed HCl–Water Clusters. Chem Rev 2016; 116:4913-36. [DOI: 10.1021/acs.chemrev.5b00506] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Amit K. Samanta
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Yimin Wang
- Department
of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - John S. Mancini
- Department
of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - Joel M. Bowman
- Department
of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States
| | - Hanna Reisler
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
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27
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Poretskiy MS, Chichinin AI, Maul C, Gericke KH. Double-arm three-dimensional ion imaging apparatus for the study of ion pair channels in resonance enhanced multiphoton ionization. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:023107. [PMID: 26931834 DOI: 10.1063/1.4936984] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a novel experimental configuration for the full quantitative characterization of the multichannel resonance enhanced multiphoton ionization (REMPI) of small molecules in cases when the ion-pair dissociation channel is important. For this purpose, a double-arm time-of-flight mass spectrometer with three-dimensional (3D) ion imaging detectors at both arms is constructed. The REMPI of HCl molecules is used to examine the constructed setup. The apparatus allows us to perform simultaneous measurements of the 3D velocity vector distributions of positive (H(+), HCl(+), and Cl(+)) and negative (Cl(-)) photoions. The characterization consists of the determination of "two-photon absorption cross sections" for the process HCl(X)+2hν → HCl*, one-photon absorption cross sections for subsequent processes HCl* + hν → HCl*, and the probability of the subsequent non-adiabatic transition HCl* → HCl(B) → H(+) + Cl(-), which leads to ionic pairs. All these data should be obtained from the analysis of the dependencies of the number of ions on the laser energy. The full characterization of the laser beam and the knowledge of the ion detection probability are necessary parts of the analysis. Detailed knowledge of losses of produced ions in the mass spectrometer before detection requires understanding and characterization of such processes like electron emission from metallic grids under ion bombardment or charge transfer between positive ions and the metal surface of the grids, like Cl(+) + (grid) → Cl(-). These important phenomena from surface science are rarely discussed in the imaging literature, and here, we try to compensate for this shortcoming.
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Affiliation(s)
- M S Poretskiy
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - A I Chichinin
- Institute of Chemical Kinetics and Combustion and Novosibirsk State University, 630090 Novosibirsk, Russia
| | - C Maul
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - K-H Gericke
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, 38106 Braunschweig, Germany
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28
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Li Z, Vendrell O, Santra R. Ultrafast Charge Transfer of a Valence Double Hole in Glycine Driven Exclusively by Nuclear Motion. PHYSICAL REVIEW LETTERS 2015; 115:143002. [PMID: 26551809 DOI: 10.1103/physrevlett.115.143002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Indexed: 06/05/2023]
Abstract
We explore theoretically the ultrafast transfer of a double electron hole between the functional groups of glycine after K-shell ionization and subsequent Auger decay. Although a large energy gap of about 15 eV initially exists between the two electronic states involved and coherent electronic dynamics play no role in the hole transfer, we find that the double hole is transferred within 3 to 4 fs between both functional ends of the glycine molecule driven solely by specific nuclear displacements and non-Born-Oppenheimer effects. The nuclear displacements along specific vibrational modes are of the order of 15% of a typical chemical bond between carbon, oxygen, and nitrogen atoms and about 30% for bonds involving hydrogen atoms. The time required for the hole transfer corresponds to less than half a vibrational period of the involved nuclear modes. This finding challenges the common wisdom that nuclear dynamics of the molecular skeleton are unimportant for charge transfer processes at the few-femtosecond time scale and shows that they can even play a prominent role. It also indicates that in x-ray imaging experiments, in which ionization is unavoidable, valence electron redistribution caused by nuclear dynamics might be much faster than previously anticipated. Thus, non-Born-Oppenheimer effects may affect the apparent electron densities extracted from such measurements.
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Affiliation(s)
- Zheng Li
- Center for Free-Electron Laser Science, DESY, Notkestraß e 85, D-22607 Hamburg, Germany
- Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Oriol Vendrell
- Center for Free-Electron Laser Science, DESY, Notkestraß e 85, D-22607 Hamburg, Germany
- Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Robin Santra
- Center for Free-Electron Laser Science, DESY, Notkestraß e 85, D-22607 Hamburg, Germany
- Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany
- Department of Physics, University of Hamburg, Jungiusstraße 9, D-20355 Hamburg, Germany
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29
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Lee SK, Cudry F, Lin YF, Lingenfelter S, Winney AH, Fan L, Li W. Coincidence ion imaging with a fast frame camera. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:123303. [PMID: 25554285 DOI: 10.1063/1.4903856] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A new time- and position-sensitive particle detection system based on a fast frame CMOS (complementary metal-oxide semiconductors) camera is developed for coincidence ion imaging. The system is composed of four major components: a conventional microchannel plate/phosphor screen ion imager, a fast frame CMOS camera, a single anode photomultiplier tube (PMT), and a high-speed digitizer. The system collects the positional information of ions from a fast frame camera through real-time centroiding while the arrival times are obtained from the timing signal of a PMT processed by a high-speed digitizer. Multi-hit capability is achieved by correlating the intensity of ion spots on each camera frame with the peak heights on the corresponding time-of-flight spectrum of a PMT. Efficient computer algorithms are developed to process camera frames and digitizer traces in real-time at 1 kHz laser repetition rate. We demonstrate the capability of this system by detecting a momentum-matched co-fragments pair (methyl and iodine cations) produced from strong field dissociative double ionization of methyl iodide.
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Affiliation(s)
- Suk Kyoung Lee
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Fadia Cudry
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Yun Fei Lin
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Steven Lingenfelter
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Alexander H Winney
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Lin Fan
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Wen Li
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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30
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Wang K, McKoy V, Hockett P, Schuurman MS. Time-resolved photoelectron spectra of CS2: dynamics at conical intersections. PHYSICAL REVIEW LETTERS 2014; 112:113007. [PMID: 24702364 DOI: 10.1103/physrevlett.112.113007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Indexed: 06/03/2023]
Abstract
We report results of the application of a fully ab initio approach for simulating time-resolved molecular-frame photoelectron angular distributions around conical intersections in CS2. The technique employs wave packet densities obtained with the multiple spawning method in conjunction with geometry- and energy-dependent photoionization matrix elements. The robust agreement of these results with measured molecular-frame photoelectron angular distributions for CS2 demonstrates that this technique can successfully elucidate, and disentangle, the underlying nuclear and photoionization dynamics around conical intersections in polyatomic molecules.
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Affiliation(s)
- Kwanghsi Wang
- A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA
| | - Vincent McKoy
- A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA
| | - Paul Hockett
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
| | - Michael S Schuurman
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
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31
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Janssen MHM, Powis I. Detecting chirality in molecules by imaging photoelectron circular dichroism. Phys Chem Chem Phys 2014; 16:856-71. [DOI: 10.1039/c3cp53741b] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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32
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Suzuki T. Femtosecond Time-Resolved Photoelectron Imaging Study of Photoinduced Molecular Dynamics. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.200600014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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33
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Lehmann CS, Ram NB, Janssen MHM. Velocity map photoelectron-photoion coincidence imaging on a single detector. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:093103. [PMID: 23020358 DOI: 10.1063/1.4749843] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Here we report on a new simplified setup for velocity map photoelectron-photoion coincidence imaging using only a single particle detector. We show that both photoelectrons and photoions can be extracted toward the same micro-channel-plate delay line detector by fast switching of the high voltages on the ion optics. This single detector setup retains essentially all the features of a standard two-detector coincidence imaging setup, viz., the high spatial resolution for electron and ion imaging, while only slightly decreasing the ion time-of-flight mass resolution. The new setup paves the way to a significant cost reduction in building a coincidence imaging setup for experiments aiming to obtain the complete correlated three-dimensional momentum distribution of electrons and ions.
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Affiliation(s)
- C Stefan Lehmann
- LaserLaB Amsterdam, VU University Amsterdam, de Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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34
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Mao R, Zhang Q, Zang J, He C, Chen M, Chen Y. Multiphoton dissociative ionization of tert-pentyl bromide near 265 nm. J Chem Phys 2011; 135:244302. [PMID: 22225151 DOI: 10.1063/1.3671368] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report on the photodissociation dynamics of tert-pentyl bromide near 265 nm investigated by time-sliced velocity map imaging. The speed and angular distributions have been analyzed for both the ground-state Br((2)P(3∕2)) atom (denoted Br) and the spin-orbit excited-state Br((2)P(1∕2)) atom (denoted Br*). The speed distributions of Br and Br* atoms are all found to consist of three Gaussian components, which correlate to three independent dissociation pathways on the excited potential energy surfaces: (1) the high translational energy (E(T)) component from the prompt dissociation along the C-Br stretching mode, (2) the middle E(T) component from the repulsive mode along the C-Br stretching coupled with some bending motions, and (3) the low E(T) component from the repulsive mode along the C-Br stretching coupled with more bending motions. More interestingly, we have also observed the tert-C(5)H(11)(+) ions in 263-267 nm. The near-zero kinetic energy distributions extracted from the three tert-C(5)H(11)(+) images near 265 nm show the typical characteristics that are attributable to multiphoton dissociative ionization, suggesting the existence of a neutral superexcited state of the parent tert-pentyl bromide molecule. The contribution of bromine atoms formed in this dissociative ionization channel adds in the total relative distribution of low E(T) component in the Br*(Br) formation channel, which reasonably explains the abnormal distributions observed in between the middle and low E(T) components in the Br*(Br) formation channel.
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Affiliation(s)
- Rui Mao
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
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35
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Wu G, Hockett P, Stolow A. Time-resolved photoelectron spectroscopy: from wavepackets to observables. Phys Chem Chem Phys 2011; 13:18447-67. [PMID: 21947027 DOI: 10.1039/c1cp22031d] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved photoelectron spectroscopy (TRPES) is a powerful tool for the study of intramolecular dynamics, particularly excited state non-adiabatic dynamics in polyatomic molecules. Depending on the problem at hand, different levels of TRPES measurements can be performed: time-resolved photoelectron yield; time- and energy-resolved photoelectron yield; time-, energy-, and angle-resolved photoelectron yield. In this pedagogical overview, a conceptual framework for time-resolved photoionization measurements is presented, together with discussion of relevant theory for the different aspects of TRPES. Simple models are used to illustrate the theory, and key concepts are further amplified by experimental examples. These examples are chosen to show the application of TRPES to the investigation of a range of problems in the excited state dynamics of molecules: from the simplest vibrational wavepacket on a single potential energy surface; to disentangling intrinsically coupled electronic and nuclear motions; to identifying the electronic character of the intermediate states involved in non-adiabatic dynamics by angle-resolved measurements in the molecular frame, the most complete measurement.
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Affiliation(s)
- Guorong Wu
- Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
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36
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Scott Hopkins W, Mackenzie SR. Communication: Imaging wavefunctions in dissociative photoionization. J Chem Phys 2011; 135:081104. [DOI: 10.1063/1.3632103] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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37
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Vredenborg A, Lehmann CS, Irimia D, Roeterdink WG, Janssen MHM. The Reaction Microscope: Imaging and Pulse Shaping Control in Photodynamics. Chemphyschem 2011; 12:1459-73. [DOI: 10.1002/cphc.201100107] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Indexed: 11/09/2022]
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Bao J, Weber PM. Electronic effects on photochemistry: the diverse reaction dynamics of highly excited stilbenes and azobenzene. J Am Chem Soc 2011; 133:4164-7. [PMID: 21370862 DOI: 10.1021/ja108598w] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ultrafast time-resolved mass spectrometry and structural dynamics experiments on trans-stilbene, cis-stilbene, and azobenzene, with excitation to high-lying electronic states, reveal a rich diversity of photochemical reaction dynamics. All processes are found to be quite unlike the well-known photochemistry on lower electronic surfaces. While in trans-stilbene, excitation at 6 eV induces a phenyl twisting motion, in cis-stilbene it leads to an ultrafast ring-closing to form 4a,4b-dihydrophenanthrene. Azobenzene dissociates on an ultrafast time scale, rather than isomerizing as it does on a lower surface. The photochemical dynamics of the sample molecules proceed along steep potential energy surfaces and conical intersections. Because of that, the dynamics are much faster than vibrational relaxation, the randomizing effects from vibrational energy scrambling are avoided, and excitation-energy specific reaction dynamics results.
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Affiliation(s)
- Jie Bao
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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Stefan Lehmann C, Bhargava Ram N, Irimia D, Janssen MHM. Photoelectron photoion coincidence imaging of ultrafast control in multichannel molecular dynamics. Faraday Discuss 2011; 153:173-87; discussion 189-212. [DOI: 10.1039/c1fd00047k] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Affiliation(s)
- Dave Townsend
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom, and Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6, Canada
| | - Benjamin J. Sussman
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom, and Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6, Canada
| | - Albert Stolow
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom, and Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6, Canada
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41
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Stolow A. Time-resolved photoelectron spectroscopy: Non-adiabatic dynamics in polyatomic molecules. INT REV PHYS CHEM 2010. [DOI: 10.1080/0144235031000092448] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Albert Stolow
- a Steacie Institute for Molecular Sciences , National Research Council of Canada , 100 Sussex Drive, Ottawa , Ontario , K1A 0R6 , Canada
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Affiliation(s)
- J.-M. Mestdagh
- a Laboratoire Francis Perrin (CNRS-URA-2453) , DSM/DRECAM/Service des Photons , Atomes et Molécules, C.E.A. Saclay, Gif-sur-Yvette cedex , F-91191 , France
| | - B. Soep
- a Laboratoire Francis Perrin (CNRS-URA-2453) , DSM/DRECAM/Service des Photons , Atomes et Molécules, C.E.A. Saclay, Gif-sur-Yvette cedex , F-91191 , France
| | - M.-A. Gaveau
- a Laboratoire Francis Perrin (CNRS-URA-2453) , DSM/DRECAM/Service des Photons , Atomes et Molécules, C.E.A. Saclay, Gif-sur-Yvette cedex , F-91191 , France
| | - J.-P. Visticot
- a Laboratoire Francis Perrin (CNRS-URA-2453) , DSM/DRECAM/Service des Photons , Atomes et Molécules, C.E.A. Saclay, Gif-sur-Yvette cedex , F-91191 , France
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Irimia D, Janssen MHM. Toward elucidating the mechanism of femtosecond pulse shaping control in photodynamics of molecules by velocity map photoelectron and ion imaging. J Chem Phys 2010; 132:234302. [DOI: 10.1063/1.3436720] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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44
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Irimia D, Petsalakis ID, Theodorakopoulos G, Janssen MHM. Coherent oscillatory femtosecond dynamics in multichannel photodynamics of NO2 studied by spatially masked electron imaging. J Phys Chem A 2010; 114:3157-66. [PMID: 19928822 DOI: 10.1021/jp909031p] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The femtosecond multiphoton photoionization and dissociation dynamics of NO(2) have been studied in a two-color pump-probe experiment at 400 and 266 nm using velocity map ion imaging in conjunction with photoelectron imaging. We report here a series of experiments focusing on the oscillatory patterns in pump-probe transients of the photoelectron signal. By using the technique of spatially masked imaging detection, we can select different photoelectron channels enabling the rapid measurement of energy selected transients with good signal-to-noise ratio. At short delay times (<300 fs) the dominant process is dissociative multiphoton ionization by 3 x 400 nm + 1 x 266 nm excitation to a repulsive potential energy surface of the NO(2)(+) cation correlating to NO(+)((1)Sigma(+)) + O((3) P) and the ejection of a 0.37 eV electron. At longer delay times (>400 fs), the release of high-energy electrons (0.88 eV) is observed attributed to a three-photon absorption at 400 nm to Rydberg and valence type excited states of neutral NO(2) leading to predissociation and the production of NO(+) + O((3)P) from a one-photon ionization at 266 nm. At longer delay times (>400 fs) a second slow (near 0 eV) photoelectron channel is observed that is associated with one photon excitation at 400 nm to the first excited A(2)B(2) state of NO(2) followed by two-photon excitation at 266 nm leading to near threshold ionization and dissociation to NO(+) + O((3)P). Distinctive oscillatory patterns were found in the pump-probe transients of the photoelectron yield for both the slow and the fast photoelectron channels but with different periods of about 750 fs (slow) or 590 fs (fast). Extensive polarization experiments are reported for both linear and circular polarized pump and probe laser geometries. We discuss the oscillatory mechanism in relation to ab initio calculations of relevant Rydberg and valence type excited states of NO(2) near 9.3 eV. We propose that an oscillating wavepacket of mixed Rydberg and valence character that predissociates is responsible for the observed oscillations in the transients of the fast (0.88 eV) photoelectron channel.
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Affiliation(s)
- Daniel Irimia
- Laser Centre and Department of Chemistry, Vrije Universiteit, de Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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Wilkinson I, Garcia IA, Whitaker BJ, Hamard JB, Blanchet V. The photodissociation of NO2 by visible and ultraviolet light. Phys Chem Chem Phys 2010; 12:15766-79. [DOI: 10.1039/c0cp01551b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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47
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Tang X, Zhou X, Niu M, Liu S, Sun J, Shan X, Liu F, Sheng L. A threshold photoelectron-photoion coincidence spectrometer with double velocity imaging using synchrotron radiation. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2009; 80:113101. [PMID: 19947711 DOI: 10.1063/1.3250872] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A novel threshold photoelectron-photoion coincidence (TPEPICO) imaging spectrometer at the U14-A beamline of the Hefei National Synchrotron Radiation Laboratory is presented. A set of open electron and ion lenses are utilized to map velocity imaging of photoelectrons and photoions simultaneously, in which a repelling electric field using an extra lens is applied to magnify images of photoelectrons instead of traditional accelerating electric field in order to suppress the contribution of energetic electrons in the threshold photoelectron spectroscopy (TPES) and the mass-selected TPEPICO spectroscopy. The typical energy resolution of TPES is measured to be 9 meV (full width at half maximum), as shown on the (2)P(1/2) ionization of argon. The measured mass resolving power for the present TPEPICO imaging spectrometer is above 900 of M/DeltaM. Subsequently as a benchmark, oxygen molecule is photoionized by monochromatic synchrotron radiation at 20.298 eV and dissociates to an oxygen atomic ion and a neutral oxygen atom, and the translation energy distribution of oxygen atomic ion is measured by the time-sliced imaging based on mass-selected TPEPICO experiment. The kinetic energy resolution of the present ion velocity imaging is better than 3% of DeltaE/E.
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Affiliation(s)
- Xiaofeng Tang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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Liu B, Zhu J, Wang B, Wang Y, Wang L. Time-Resolved Dynamics of NO2 in Its Conical Intersection Region. J Phys Chem A 2009; 113:13839-44. [DOI: 10.1021/jp907041a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Benkang Liu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Dalian 116023, China, and Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
| | - Jingyi Zhu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Dalian 116023, China, and Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
| | - Bingxing Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Dalian 116023, China, and Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
| | - Yanqiu Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Dalian 116023, China, and Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
| | - Li Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Dalian 116023, China, and Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
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49
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Revealing femtosecond multiphoton induced multichannel molecular ionization and fragmentation dynamics by photoelectron–photoion coincidence imaging. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.07.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
Photofragment spectroscopy is combined with imaging techniques and time-resolved measurements of photoions and photoelectrons to explore the predissociation dynamics of weakly bound molecules. Recent experimental advances include measurements of pair-correlated distributions, in which energy disposal in one cofragment is correlated with a state-selected level of the other fragment, and femtosecond pump-probe experiments, in some cases with coincidence detection. An application in which coincident measurements are carried out in the molecular frame is also described. To illustrate these state-selective and time-resolved techniques, we review two recent applications: (a) the photoinitiated dissociation of the covalently bound NO dimer on the ground and excited electronic states and the role of state couplings and (b) the state-selected vibrational predissociation of hydrogen-bonded acetylene dimers with HCl (acid) and ammonia (base) and the importance of angular momentum constraints. We highlight the crucial role of theoretical models in interpreting results.
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Affiliation(s)
- Hanna Reisler
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482
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