1
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Abderahem M, Zhang Y, Liu Z, Shan X, Chen X. Vibrational effects on the valence electronic structure of acetaldehyde: An electron momentum spectroscopy investigation. Chem Phys 2023. [DOI: 10.1016/j.chemphys.2023.111892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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2
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Zhang Y, Gong M, Liu Z, Niu S, Shan X, Chen X. Experimental and Theoretical Study on Electron Momentum Spectroscopy of SF 6: Distorted-Wave and Vibrational Motion. J Phys Chem A 2023; 127:1252-1258. [PMID: 36705984 DOI: 10.1021/acs.jpca.2c09072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The vibrational and distorted-wave effects are usually invoked to explain the measured electron momentum profiles for molecular orbitals. The vibrational effect can be accounted for quantitatively by a harmonic analytical quantum mechanical approach within the plane-wave impulse approximation (PWIA). On the other hand, quantitative calculation considering the distorted-wave effect was available only recently by a multicenter-three-distorted-wave (MCTDW) method (Phys. Rev. A2022, 105, 042805). Here, we report a joint experimental and theoretical investigation on electron momentum spectroscopy of SF6. The experiments were performed using a high-sensitivity (e, 2e) spectrometer employing non-coplanar symmetric geometry with incident electron energy equal to 1200 eV + binding energy. The experimental electron momentum profiles are compared with theoretical calculations by the MCTDW method at equilibrium geometry and by the PWIA method both at equilibrium geometry and considering vibrational motions. For all the measured orbitals, large discrepancies were observed between the experiments and the PWIA calculations at equilibrium geometry. For the highest occupied molecular orbital 1t1g, the vibrational effect can partly explain the high intensity of the experimental momentum profile at low momenta. For the other orbitals, the influence of the vibrational effect is negligible. On the other hand, the MCTDW calculations improve the agreement with the experiments for all the observed orbitals, indicating that the distorted-wave effect plays an important role in reproducing the measured momentum profiles of SF6.
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Affiliation(s)
- Yuting Zhang
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui230026, China
| | - Maomao Gong
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui230026, China
| | - Zhaohui Liu
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui230026, China
| | - Shanshan Niu
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui230026, China
| | - Xu Shan
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui230026, China
| | - Xiangjun Chen
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui230026, China
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3
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Onitsuka Y, Tachibana Y, Takahashi M. Asymptotic behavior of the electron-atom Compton profile due to the intramolecular H-atom motion in H 2. Phys Chem Chem Phys 2022; 24:19716-19721. [PMID: 35792708 DOI: 10.1039/d2cp02461f] [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
We report the asymptotic behavior of the electron-atom Compton profile due to the intramolecular H-atom motion in H2. The experiment has been performed at a scattering angle of 135° and at incident electron energies from 1.0 to 2.2 keV, thus covering a momentum transfer (K) range from 15.8 to 23.5 a.u. It is shown that with the increase in K, the Compton profile changes in shape and becomes more symmetric. Furthermore, it is found that the experiment reaches the limit of sufficiently large K at an incident electron energy of 2.0 keV, where the plane-wave impulse approximation is applicable to directly relate the Compton profile to the momentum distribution of the H atom.
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Affiliation(s)
- Yuuki Onitsuka
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
| | - Yuichi Tachibana
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, 980-8577, Japan.
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4
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Development of an Electron-Atom Compton Scattering Apparatus Using a Picosecond Pulsed Electron Gun. ATOMS 2021. [DOI: 10.3390/atoms9010019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
An apparatus has been developed for electron-atom Compton scattering experiments that can employ a pulsed laser and a picosecond pulsed electron beam in a pump-and-probe scheme. The design and technical details of the apparatus are described. Furthermore, experimental results on the Xe atom in its ground state are presented to illustrate the performance of the pulsed electron gun and the detection and spectrometric capabilities for scattered electrons. The scope of future application is also discussed, involving real-time measurement of intramolecular force acting on each constituent atom with different mass numbers, in a transient, evolving system during a molecular reaction.
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5
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Watanabe N, Takahashi K, Sato K, Takahashi M. Temperature-Dependent Electron Momentum Spectroscopy on the Molecular Orbitals of Dimethyl Ether. J Phys Chem A 2020; 124:10258-10265. [PMID: 33258373 DOI: 10.1021/acs.jpca.0c08799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper investigates vibrational excitation effects on valence electron momentum distributions of dimethyl ether. A symmetric noncoplanar (e, 2e) experiment has been performed for the molecule at a high temperature (980 K) as well as at room temperature (300 K). For comparison, theoretical calculations with vibrational effects being involved have also been carried out. Changes of the momentum profiles with the rise of temperature are observed for the 2b1 and 6a1 orbitals, indicating that distortion of these molecular orbitals is appreciably enhanced upon excitation of the methyl torsional vibrations. The present study provides a way for exploring the influence of vibrational excitation on electronic wavefunctions of molecules.
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Affiliation(s)
- Noboru Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Keita Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Kimihiro Sato
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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6
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Liu Z, Tang Y, Niu S, Shan X, Xu C, Chen X. Electron Momentum Spectroscopy Study on the Valence Electronic Structure of Dimethyl Sulfide Considering Vibrational Effects. J Phys Chem A 2020; 124:8551-8561. [PMID: 32966068 DOI: 10.1021/acs.jpca.0c07438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report an electron momentum spectroscopy study on the valence electronic structure of dimethyl sulfide. The binding energy and electron momentum profiles are measured using a high-sensitivity (e, 2e) apparatus employing a symmetric non-coplanar geometry at an incident energy of 1200 eV plus binding energy. The measurements are compared with the theoretical calculations by density functional theory performed both at equilibrium molecular geometry and by considering vibrational effects through a harmonic analytical quantum mechanical approach. The results demonstrate a significant influence of nuclear vibrational motions on the momentum profiles for valence orbitals of dimethyl sulfide, especially for 5b2, 1a2, and 4b2. A detailed analysis shows that the observed vibrational effects come mainly from vibrational normal modes breaking the mirror symmetry of (CH3)2S with respect to a plane perpendicular to the O-S-O plane.
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Affiliation(s)
- ZhaoHui Liu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - YaGuo Tang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - ShanShan Niu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xu Shan
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - ChunKai Xu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - XiangJun Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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7
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Jones D, Wang F, Winkler D, Brunger M. The electronic structure of bicyclo[2.2.2]octa-2,5-dione. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Vibrational and distorted-wave effects on the highest occupied molecular orbital electronics structure of tetrachloromethane. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2020.110794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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9
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Watanabe N, Sato K, Takahashi M. Electron momentum spectroscopy study on the valence electronic structure of methyl formate. J Chem Phys 2019; 150:194306. [PMID: 31117792 DOI: 10.1063/1.5097201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report an electron momentum spectroscopy study on methyl formate. A symmetric noncoplanar (e, 2e) experiment has been performed at an incident electron energy of 1.2 keV and electron momentum profiles of the valence orbitals have been obtained. On the basis of the result, assignments of the 10a'-1 and 1a″-1 bands have been made to resolve a contradiction between photoelectron spectroscopy and Penning ionization electron spectroscopy studies. Comparisons between experiment and theory reveal that the influence of the molecular vibration has to be taken into account for a proper understanding of the electron momentum profiles. Contributions of individual vibrational normal modes have also been investigated in detail by means of the harmonic analytical quantum mechanical approach.
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Affiliation(s)
- Noboru Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Kimihiro Sato
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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10
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Tang Y, Shan X, Liu Z, Niu S, Wang E, Chen X. Development of an electron momentum spectrometer for time-resolved experiments employing nanosecond pulsed electron beam. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:033101. [PMID: 29604728 DOI: 10.1063/1.5018665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The low count rate of (e, 2e) electron momentum spectroscopy (EMS) has long been a major limitation of its application to the investigation of molecular dynamics. Here we report a new EMS apparatus developed for time-resolved experiments in the nanosecond time scale, in which a double toroidal energy analyzer is utilized to improve the sensitivity of the spectrometer and a nanosecond pulsed electron gun with a repetition rate of 10 kHz is used to obtain an average beam current up to nA. Meanwhile, a picosecond ultraviolet laser with a repetition rate of 5 kHz is introduced to pump the sample target. The time zero is determined by photoionizing the target using a pump laser and monitoring the change of the electron beam current with time delay between the laser pulse and electron pulse, which is influenced by the plasma induced by the photoionization. The performance of the spectrometer is demonstrated by the EMS measurement on argon using a pulsed electron beam, illustrating the potential abilities of the apparatus for investigating the molecular dynamics in excited states when employing the pump-probe scheme.
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Affiliation(s)
- Yaguo Tang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xu Shan
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhaohui Liu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shanshan Niu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Enliang Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiangjun Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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11
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Zhu Y, Ma X, Lou W, Wang M, Yang C. Symmetry-broken effects on electron momentum spectroscopy caused by adiabatic vibration. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.09.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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12
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Morini F, Watanabe N, Kojima M, Deleuze MS, Takahashi M. Influence of molecular vibrations on the valence electron momentum distributions of adamantane. J Chem Phys 2017. [DOI: 10.1063/1.4977060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Filippo Morini
- Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Noboru Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Masataka Kojima
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Michael Simon Deleuze
- Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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13
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Tang Y, Shan X, Niu S, Liu Z, Wang E, Watanabe N, Yamazaki M, Takahashi M, Chen X. Electron Momentum Spectroscopy Investigation of Molecular Conformations of Ethanol Considering Vibrational Effects. J Phys Chem A 2017; 121:277-287. [PMID: 27998060 DOI: 10.1021/acs.jpca.6b10009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interpretation of experimental electron momentum distributions (EMDs) of ethanol, one of the simplest molecules having conformers, has confused researchers for years. High-level calculations of Dyson orbital EMDs by thermally averaging the gauche and trans conformers as well as molecular dynamical simulations failed to quantitatively reproduce the experiments for some of the outer valence orbitals. In this work, the valence shell electron binding energy spectrum and EMDs of ethanol are revisited by the high-sensitivity electron momentum spectrometer employing symmetric noncoplanar geometry at an incident energy of 1200 eV plus binding energy, together with a detailed analysis of the influence of vibrational motions on the EMDs for the two conformers employing a harmonic analytical quantum mechanical (HAQM) approach by taking into account all of the vibrational modes. The significant discrepancies between theories and experiments in previous works have now been interpreted quantitatively, indicating that the vibrational effect plays a significant role in reproducing the experimental results, not only through the low-frequency OH and CH3 torsion modes but also through other high-frequency ones. Rational explanation of experimental momentum profiles provides solid evidence that the trans conformer is slightly more stable than the gauche conformer, in accordance with thermodynamic predictions and other experiments. The case of ethanol demonstrates the significance of considering vibrational effects when performing a conformational study on flexible molecules using electron momentum spectroscopy.
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Affiliation(s)
- Yaguo Tang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Xu Shan
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Shanshan Niu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Zhaohui Liu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Enliang Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Noboru Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Sendai 980-8577, Japan
| | - Masakazu Yamazaki
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Sendai 980-8577, Japan
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Sendai 980-8577, Japan
| | - Xiangjun Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
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14
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Jones DB, Ali E, Ning CG, Colgan J, Ingólfsson O, Madison DH, Brunger MJ. Electron impact ionization dynamics of para-benzoquinone. J Chem Phys 2016; 145:164306. [DOI: 10.1063/1.4965919] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- D. B. Jones
- School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide SA 5001, Australia
| | - E. Ali
- Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
| | - C. G. Ning
- Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
| | - J. Colgan
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - O. Ingólfsson
- Science Institute and Department of Chemistry, University of Iceland, Dunhagi 3, 107 Reykjavík, Iceland
| | - D. H. Madison
- Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
| | - M. J. Brunger
- School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide SA 5001, Australia
- Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia
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15
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Tang Y, Shan X, Yang J, Niu S, Zhang Z, Watanabe N, Yamazaki M, Takahashi M, Chen X. Vibrational Effects on Electron Momentum Distributions of Outer-Valence Orbitals of Oxetane. J Phys Chem A 2016; 120:6855-63. [PMID: 27494262 DOI: 10.1021/acs.jpca.6b06706] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Vibrational effects on electron momentum distributions (EMDs) of outer-valence orbitals of oxetane are computed with a comprehensive consideration of all vibrational modes. It is found that vibrational motions influence EMDs of all outer-valence orbitals noticeably. The agreement between theoretical and experimental momentum profiles of the first five orbitals is greatly improved when including molecular vibrations in the calculation. In particular, the large turn-up at low momentum in the experimental momentum profile of the 3b1 orbital is well interpreted by vibrational effects, indicating that, besides the low-frequency ring-puckering mode, C-H stretching motion also plays a significant role in affecting EMDs of outer-valence orbitals of oxetane. The case of oxetane exhibits the significance of checking vibrational effects when performing electron momentum spectroscopy measurements.
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Affiliation(s)
- Yaguo Tang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Xu Shan
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Jing Yang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Shanshan Niu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Zhe Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
| | - Noboru Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Sendai 980-8577, Japan
| | - Masakazu Yamazaki
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Sendai 980-8577, Japan
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , Sendai 980-8577, Japan
| | - Xiangjun Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China , Hefei, Anhui 230026, China
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16
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Jones DB, Ali E, Nixon KL, Limão-Vieira P, Hubin-Franskin MJ, Delwiche J, Ning CG, Colgan J, Murray AJ, Madison DH, Brunger MJ. Electron- and photon-impact ionization of furfural. J Chem Phys 2015; 143:184310. [DOI: 10.1063/1.4935444] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- D. B. Jones
- School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - E. Ali
- Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
| | - K. L. Nixon
- Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brazil
- School of Biology, Chemistry and Forensic Science, University of Wolverhampton, Wolverhampton WV1 1LY, United Kingdom
| | - P. Limão-Vieira
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - M.-J. Hubin-Franskin
- Départment de Chimie, Université de Liège, Institut de Chimie-Bât. B6C, B-4000 Liège 1, Belgium
| | - J. Delwiche
- Départment de Chimie, Université de Liège, Institut de Chimie-Bât. B6C, B-4000 Liège 1, Belgium
| | - C. G. Ning
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - J. Colgan
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - A. J. Murray
- Photon Science Institute, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - D. H. Madison
- Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
| | - M. J. Brunger
- School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
- Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia
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17
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Morini F, Watanabe N, Kojima M, Deleuze MS, Takahashi M. Electron momentum spectroscopy of dimethyl ether taking account of nuclear dynamics in the electronic ground state. J Chem Phys 2015; 143:134309. [PMID: 26450316 DOI: 10.1063/1.4931918] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The influence of nuclear dynamics in the electronic ground state on the (e,2e) momentum profiles of dimethyl ether has been analyzed using the harmonic analytical quantum mechanical and Born-Oppenheimer molecular dynamics approaches. In spite of fundamental methodological differences, results obtained with both approaches consistently demonstrate that molecular vibrations in the electronic ground state have a most appreciable influence on the momentum profiles associated to the 2b1, 6a1, 4b2, and 1a2 orbitals. Taking this influence into account considerably improves the agreement between theoretical and newly obtained experimental momentum profiles, with improved statistical accuracy. Both approaches point out in particular the most appreciable role which is played by a few specific molecular vibrations of A1, B1, and B2 symmetries, which correspond to C-H stretching and H-C-H bending modes. In line with the Herzberg-Teller principle, the influence of these molecular vibrations on the computed momentum profiles can be unraveled from considerations on the symmetry characteristics of orbitals and their energy spacing.
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Affiliation(s)
- Filippo Morini
- Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Noboru Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Masataka Kojima
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Michael Simon Deleuze
- Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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18
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Yamazaki M, Oishi K, Nakazawa H, Zhu C, Takahashi M. Molecular orbital imaging of the acetone S2 excited state using time-resolved (e, 2e) electron momentum spectroscopy. PHYSICAL REVIEW LETTERS 2015; 114:103005. [PMID: 25815930 DOI: 10.1103/physrevlett.114.103005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Indexed: 06/04/2023]
Abstract
We report a time-resolved (e, 2e) experiment on the deuterated acetone molecule in the S2 Rydberg state with a lifetime of 13.5 ps. The acetone S2 state was prepared by a 195 nm pump laser and probed with electron momentum spectroscopy using a 1.2 keV incident electron beam of 1 ps temporal width. In spite of the low data statistics as well as of the limited time resolution (±35 ps) due to velocity mismatch, the experimental results clearly demonstrate that electron momentum spectroscopy measurements of short-lived transient species are feasible, opening the door to time-resolved orbital imaging in momentum space.
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Affiliation(s)
- Masakazu Yamazaki
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Keiya Oishi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Hiroyuki Nakazawa
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Chaoyuan Zhu
- Department of Applied Chemistry, Institute of Molecular Science, National Chiao-Tung University, Hsinchu 30050, Taiwan
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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Morini F, Deleuze MS, Watanabe N, Takahashi M. Theoretical study of molecular vibrations in electron momentum spectroscopy experiments on furan: an analytical versus a molecular dynamical approach. J Chem Phys 2015; 142:094308. [PMID: 25747082 DOI: 10.1063/1.4913642] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The influence of thermally induced nuclear dynamics (molecular vibrations) in the initial electronic ground state on the valence orbital momentum profiles of furan has been theoretically investigated using two different approaches. The first of these approaches employs the principles of Born-Oppenheimer molecular dynamics, whereas the so-called harmonic analytical quantum mechanical approach resorts to an analytical decomposition of contributions arising from quantized harmonic vibrational eigenstates. In spite of their intrinsic differences, the two approaches enable consistent insights into the electron momentum distributions inferred from new measurements employing electron momentum spectroscopy and an electron impact energy of 1.2 keV. Both approaches point out in particular an appreciable influence of a few specific molecular vibrations of A1 symmetry on the 9a1 momentum profile, which can be unravelled from considerations on the symmetry characteristics of orbitals and their energy spacing.
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Affiliation(s)
- Filippo Morini
- Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Michael S Deleuze
- Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium
| | - Noboru Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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20
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Watanabe N, Yamazaki M, Takahashi M. Vibrational effects on valence electron momentum distributions of CH2F2. J Chem Phys 2014; 141:244314. [PMID: 25554158 DOI: 10.1063/1.4904705] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We report an electron momentum spectroscopy study of vibrational effects on the electron momentum distributions for the outer valence orbitals of difluoromethane (CH2F2). The symmetric noncoplanar (e,2e) experiment has been performed at an incident electron energy of 1.2 keV. Furthermore, a theoretical calculation of the electron momentum distributions of the CH2F2 molecule has been carried out with vibrational effects being involved. It is shown from comparisons between experiment and theory that it is essential to take into account influences of the CH2 asymmetric stretching and CH2 rocking vibrational modes for a proper understanding of the electron momentum distribution of the 2b1 orbital having the CH-bonding character. The results of CH2F2and additional theoretical calculations for (CH3)2O and H2CO molecules strongly suggest that vibrational effects on electron momentum distributions tend to be appreciable for non-total symmetry molecular orbitals delocalized over some equivalent CH-bond sites.
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Affiliation(s)
- Noboru Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Masakazu Yamazaki
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Masahiko Takahashi
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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21
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Yamazaki M, Kasai Y, Oishi K, Nakazawa H, Takahashi M. Development of an (e,2e) electron momentum spectroscopy apparatus using an ultrashort pulsed electron gun. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:063105. [PMID: 23822331 DOI: 10.1063/1.4809792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
An (e,2e) apparatus for electron momentum spectroscopy (EMS) has been developed, which employs an ultrashort-pulsed incident electron beam with a repetition rate of 5 kHz and a pulse duration in the order of a picosecond. Its instrumental design and technical details are reported, involving demonstration of a new method for finding time-zero. Furthermore, EMS data for the neutral Ne atom in the ground state measured by using the pulsed electron beam are presented to illustrate the potential abilities of the apparatus for ultrafast molecular dynamics, such as by combining EMS with the pump-and-probe technique.
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Affiliation(s)
- M Yamazaki
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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22
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Watanabe N, Yamazaki M, Takahashi M. Vibrational effects on valence electron momentum distributions of ethylene. J Chem Phys 2012; 137:114301. [DOI: 10.1063/1.4752653] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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23
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Watanabe N, Chen X, Takahashi M. Interference effects on (e, 2e) electron momentum profiles of CF4. PHYSICAL REVIEW LETTERS 2012; 108:173201. [PMID: 22680860 DOI: 10.1103/physrevlett.108.173201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Indexed: 06/01/2023]
Abstract
Interference effects on electron momentum profiles have been studied using binary (e, 2e) spectroscopy for the three outermost molecular orbitals of CF(4), which are composed of the F 2p nonbonding atomic orbitals. An analysis of the measured spherically averaged electron momentum densities has clearly shown the presence of oscillatory structures having direct information about the internuclear distance between the F atoms. Furthermore, it is demonstrated that the phase of the oscillatory structures depends upon the orientation in space of the constituent atomic orbitals.
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Affiliation(s)
- Noboru Watanabe
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
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24
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Selvam L, Chen FF, Wang F. Methylation of zebularine investigated using density functional theory calculations. J Comput Chem 2011; 32:2077-83. [PMID: 21541952 DOI: 10.1002/jcc.21785] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 12/01/2010] [Accepted: 02/10/2011] [Indexed: 11/09/2022]
Abstract
Deoxyribonucleic acid (DNA) methylation is an epigenetic phenomenon, which adds methyl groups into DNA. This study reveals methylation of a nucleoside antibiotic drug 1-(β-D-ribofuranosyl)-2-pyrimidinone (zebularine or zeb) with respect to its methylated analog, 1-(β-D-ribofuranosyl)-5-methyl-2-pyrimidinone (d5) using density functional theory calculations in valence electronic space. Very similar infrared spectra suggest that zeb and d5 do not differ by types of the chemical bonds, but distinctly different Raman spectra of the nucleoside pair reveal that the impact caused by methylation of zeb can be significant. Further valence orbital-based information details on valence electronic structural changes caused by methylation of zebularine. Frontier orbitals in momentum space and position space of the molecules respond differently to methylation. Based on the additional methyl electron density concentration in d5, orbitals affected by the methyl moiety are classified into primary and secondary contributors. Primary methyl contributions include MO8 (57a), MO18 (47a), and MO37 (28a) of d5, which concentrates on methyl and the base moieties, suggest certain connection to their Frontier orbitals. The primary and secondary methyl affected orbitals provide useful information on chemical bonding mechanism of the methylation in zebularine.
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Affiliation(s)
- Lalitha Selvam
- Environment and Biotechnology Centre, Faculty of Life and Social Sciences, Swinburne University of Technology, Hawthorn, Melbourne, Victoria 3122 Australia
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Bellm S, Lower J, Weigold E, Mueller DW. Fully differential molecular-frame measurements for the electron-impact dissociative ionization of H2. PHYSICAL REVIEW LETTERS 2010; 104:023202. [PMID: 20366592 DOI: 10.1103/physrevlett.104.023202] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Indexed: 05/29/2023]
Abstract
We present fully differential state-resolved experimental data for the dissociative ionization of molecular hydrogen induced through electron impact. Molecular-frame ionization cross sections are derived for transitions from the X{1}Sigma{g}{+} molecular ground state to the 1ssigma{g}, 2psigma{u}, 2ssigma{g}, and 2ppi{u} states of H2+. For transitions to the 2ssigma{g} and 2ppi{u} states, a strong orientation dependence in the cross sections is revealed, with "side-on" preferred to "end-on" collisions and a propensity for the fragment proton to emerge along the normal to the scattering plane.
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Affiliation(s)
- S Bellm
- AMPL, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200, Australia
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