1
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Weike N, Eisfeld W, Dunseath KM, Viel A. Hydrogen-iodine scattering. II. Rovibronic analysis and collisional dynamics. J Chem Phys 2024; 161:014302. [PMID: 38953441 DOI: 10.1063/5.0219156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Accepted: 06/06/2024] [Indexed: 07/04/2024] Open
Abstract
Our recently published [Weike et al., J. Chem. Phys. 159, 244119 (2023)] spin-orbit coupled diabatic potential energy model for HI is used in a thorough analysis of bound and quasi-bound states as well as elastic and inelastic processes in H + I collisions. The potential energy model, designed explicitly for studying scattering, accurately describes the various couplings in the system, which lead to complex dynamics. Ro-vibronic bound and quasi-bound states related to the adiabatic electronic ground state and an excited electronic state are analyzed. Calculations using the full 104 × 104 diabatic matrix model or a single adiabatic state are compared in order to investigate approximations in the latter. Elastic and inelastic scattering cross sections as well as thermal rates between the ground and first excited fine structure levels of iodine are computed for collision energies up to 12 500 cm-1. Resonances related to the quasi-bound states are analyzed in terms of their energy, width, lifetime, and decay probabilities. The effect of different resonances on the thermal rates is discussed. Resonances between 30 000 and 40 000 cm-1 are also studied for selected values of the total angular momentum, in particular their decay probabilities into different final states of iodine and hence their potential effect on branching ratios in photodissociation of HI.
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Affiliation(s)
- Nicole Weike
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Wolfgang Eisfeld
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Kevin M Dunseath
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes)-UMR 6251, F-35000 Rennes, France
| | - Alexandra Viel
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes)-UMR 6251, F-35000 Rennes, France
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2
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Weike N, Viel A, Eisfeld W. Hydrogen-iodine scattering. I. Development of an accurate spin-orbit coupled diabatic potential energy model. J Chem Phys 2023; 159:244119. [PMID: 38156638 DOI: 10.1063/5.0186787] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 12/05/2023] [Indexed: 01/03/2024] Open
Abstract
The scattering of H by I is a prototypical model system for light-heavy scattering in which relativistic coupling effects must be taken into account. Scattering calculations depend strongly on the accuracy of the potential energy surface (PES) model. The methodology to obtain such an accurate PES model suitable for scattering calculations is presented, which includes spin-orbit (SO) coupling within the Effective Relativistic Coupling by Asymptotic Representation (ERCAR) approach. In this approach, the SO coupling is determined only for the atomic states of the heavy atom, and the geometry dependence of the SO effect is accounted for by a diabatization with respect to asymptotic states. The accuracy of the full model, composed of a Coulomb part and the SO model, is achieved in the following ways. For the SO model, the extended ERCAR approach is applied, which accounts for both intra-state and inter-state SO coupling, and an extended number of diabatic states are included. The corresponding coupling constants for the SO operator are obtained from experiments, which are more accurate than computed values. In the Coulomb Hamiltonian model, special attention is paid to the long range behavior and accurate c6 dispersion coefficients. The flexibility and accuracy of this Coulomb model are achieved by combining partial models for three different regions. These are merged via artificial neural networks, which also refine the model further. In this way, an extremely accurate PES model for hydrogen iodide is obtained, suitable for accurate scattering calculations.
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Affiliation(s)
- Nicole Weike
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Alexandra Viel
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes)-UMR 6251, F-35000 Rennes, France
| | - Wolfgang Eisfeld
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
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3
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Jiang MX, Kvaran Á. High energy state interactions, energetics and multiphoto-fragmentation processes of HI. Phys Chem Chem Phys 2022; 24:6676-6689. [PMID: 35234758 DOI: 10.1039/d1cp05714f] [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
Mass resolved multiphoton ionization data for two-photon resonant excitations (REMPI) in the 69 000-79 000 cm-1 region were recorded for HI. REMPI spectra of fragment and molecular ions were derived from the data and analysed to obtain information relevant to the state interactions, energetics and photofragmentation processes of intermediate Rydberg and ion-pair states (HI**). Spectral perturbations observed as line shifts and intensity anomalies acted complementarily to demonstrate the effects of the state interactions. The interaction strength and character mixing of Rydberg states and Rydberg and ion-pair states of different interaction types and the states energetics were quantified by deperturbation analysis for the high energy region of 75 000-79 000 cm-1, which is dense in states. Energetics of new, not previously observed, Rydberg states, detected in the lower energy excitation region of 69 000-75 000 cm-1 was characterized by simulation calculations. Ion intensity borrowing effects, found in the spectra of interacting states, are evidence of alterations in two-photon transition probabilities due to state mixing. Based on variations in relative spectral line intensities the major photofragmentation processes involved are proposed. These involve one-photon excitation of the intermediate states (HI**) to form repulsive superexcited states (HI#) followed by autoionization, dissociation, photodissociation and photoionization processes to form ions. The importance of state interactions in multiphoton-fragmentation processes is evident from the work.
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Affiliation(s)
- Meng-Xu Jiang
- Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík, Iceland.
| | - Ágúst Kvaran
- Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík, Iceland.
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4
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Abstract
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We have developed
an instrument that uses photolysis of hydrogen
halides to produce nearly monoenergetic hydrogen atom beams and Rydberg
atom tagging to obtain accurate angle-resolved time-of-flight distributions
of atoms scattered from surfaces. The surfaces are prepared under
strict ultrahigh vacuum conditions. Data from these experiments can
provide excellent benchmarks for theory, from which it is possible
to obtain an atomic scale understanding of the underlying dynamical
processes governing H atom adsorption. In this way, the mechanism
of adsorption on metals is revealed, showing a penetration–resurfacing
mechanism that relies on electronic excitation of the metal by the
H atom to succeed. Contrasting this, when H atoms collide at graphene
surfaces, the dynamics of bond formation involving at least four carbon
atoms govern adsorption. Future perspectives of H atom scattering
from surfaces are also outlined.
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Affiliation(s)
- Oliver Bünermann
- Institute for Physical Chemistry, Georg-August-University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany.,Department of Dynamics at Surfaces, Max-Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany.,International Center for Advanced Studies of Energy Conversion, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany
| | - Alexander Kandratsenka
- Department of Dynamics at Surfaces, Max-Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany
| | - Alec M Wodtke
- Institute for Physical Chemistry, Georg-August-University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany.,Department of Dynamics at Surfaces, Max-Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany.,International Center for Advanced Studies of Energy Conversion, Georg-August University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany
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5
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Hafliðason A, Jiang MX, Kvaran Á. Photo- and autoionization processes of superexcited iodine atoms in MPI of CH3I and HI. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2020.111016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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6
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Sofikitis D, Kannis CS, Boulogiannis GK, Katsoprinakis GE, Rakitzis TP. Photofragment spin-polarization measurements via magnetization quantum beats: dynamics of DI photodissociation. Phys Chem Chem Phys 2019; 21:14000-14004. [PMID: 30604785 DOI: 10.1039/c8cp07079b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the electron-spin polarization of D atoms from the photodissociation of DI, at 213 nm and 266 nm, by measuring the magnetization quantum beats of the D atoms with a pick-up coil. We determine that the polarization P is large at both wavelengths (|P|∼ 1), however it is positive at 213 nm, and negative at 266 nm. These results, in both cases, are of opposite sign to calculations, which assume adiabatic dissociation along the A1Π1 or a3Π1 states. We interpret these results as evidence that nonadiabatic coupling between these states needs to be included for the theoretical treatment of DI photodissociation.
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Affiliation(s)
- Dimitris Sofikitis
- Department of Physics, University of Crete, 71003 Heraklion-Crete, Greece and Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion-Crete, Greece.
| | - Chrysovalantis S Kannis
- Department of Physics, University of Crete, 71003 Heraklion-Crete, Greece and Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion-Crete, Greece.
| | - Gregoris K Boulogiannis
- Department of Physics, University of Crete, 71003 Heraklion-Crete, Greece and Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion-Crete, Greece.
| | - Georgios E Katsoprinakis
- Department of Physics, University of Crete, 71003 Heraklion-Crete, Greece and Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion-Crete, Greece.
| | - T Peter Rakitzis
- Department of Physics, University of Crete, 71003 Heraklion-Crete, Greece and Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion-Crete, Greece.
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7
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Su S, Dorenkamp Y, Yu S, Wodtke AM, Dai D, Yuan K, Yang X. Vacuum ultraviolet photodissociation of hydrogen bromide. Phys Chem Chem Phys 2018; 18:15399-405. [PMID: 27210285 DOI: 10.1039/c6cp01956k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photodissociation dynamics of HBr at a series of photolysis wavelengths in the range of 123.90-125.90 nm and at around 137.0 nm have been studied using the H atom Rydberg "tagging" time-of-flight technique. The branching fractions between the channels forming ground Br((2)P3/2) and spin-orbit excited Br((2)P1/2) atoms together with the angular distributions of the products corresponding to these two channels have been measured. The photolysis wavelengths in this work excited the HBr molecule from the ground state X (1)Σ(+) to various Rydberg states and the V (1)Σ(+) ion-pair valence state. Predissociation via these states displays rich behavior, indicating the influence of the nature of initially excited states and the coupling to other bound or repulsive states on the predissociation dynamics.
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Affiliation(s)
- Shu Su
- State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China. and University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Yvonne Dorenkamp
- Institut fur PhysikalischeChemie, Georg-August-Universitat and Max-Planck-Institut fur biophysikalischeChemie, Gottingen, Germany
| | - Shengrui Yu
- State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
| | - Alec M Wodtke
- Institut fur PhysikalischeChemie, Georg-August-Universitat and Max-Planck-Institut fur biophysikalischeChemie, Gottingen, Germany
| | - Dongxu Dai
- State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
| | - Kaijun Yuan
- State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
| | - Xueming Yang
- State key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
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8
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Hróðmarsson HR, Kvaran Á. Revealing photofragmentation dynamics through interactions between Rydberg states: REMPI of HI as a case study. Phys Chem Chem Phys 2015; 17:32517-27. [PMID: 26593395 DOI: 10.1039/c5cp06185g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High energy regions of molecular electronic states are largely characterized by the nature and involvement of Rydberg states. Whereas there are a number of observed dynamical processes that are due to interactions between Rydberg and valence states, reports on the corresponding effect of Rydberg-Rydberg state interaction in the literature are scarce. Here we report a detailed characterization of the effects of interactions between two Rydberg states on photofragmentation processes, for a hydrogen halide molecule. Perturbation effects, showing as rotational line shifts, intensity alterations and line-broadenings in REMPI spectra of HI, for two-photon resonance excitations to the j(3)Σ(-)(0(+); v' = 0) and k(3)Π1(v' = 2) Rydberg states, are analyzed. The data reveal pathways of further photofragmentation processes involving photodissociation, autoionization and photoionization affected by the Rydberg-Rydberg state interactions as well as the involvement of other states, close in energy. Detailed mechanisms of the involved processes are proposed.
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Affiliation(s)
| | - Ágúst Kvaran
- Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík, Iceland.
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9
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Vidma KV, Parker DH, Bogdanchikov GA, Baklanov AV, Kochubei SA. Ionic Pathways following UV Photoexcitation of the (HI)2 van der Waals Dimer. J Phys Chem A 2009; 114:3067-73. [DOI: 10.1021/jp9067679] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Konstantin V. Vidma
- Institute for Molecules and Materials, Radboud University Nijmegen, Heijendaalseweg 135, 6525 ED Nijmegen, The Netherlands, Institute of Chemical Kinetics and Combustion, Institutskaya Street 3, Novosibirsk 630090 Russia, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia, and Institute of Semiconductor Physics, Academician Lavrentiev Ave. 13, Novosibirsk 630090, Russia
| | - David H. Parker
- Institute for Molecules and Materials, Radboud University Nijmegen, Heijendaalseweg 135, 6525 ED Nijmegen, The Netherlands, Institute of Chemical Kinetics and Combustion, Institutskaya Street 3, Novosibirsk 630090 Russia, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia, and Institute of Semiconductor Physics, Academician Lavrentiev Ave. 13, Novosibirsk 630090, Russia
| | - Georgii A. Bogdanchikov
- Institute for Molecules and Materials, Radboud University Nijmegen, Heijendaalseweg 135, 6525 ED Nijmegen, The Netherlands, Institute of Chemical Kinetics and Combustion, Institutskaya Street 3, Novosibirsk 630090 Russia, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia, and Institute of Semiconductor Physics, Academician Lavrentiev Ave. 13, Novosibirsk 630090, Russia
| | - Alexey V. Baklanov
- Institute for Molecules and Materials, Radboud University Nijmegen, Heijendaalseweg 135, 6525 ED Nijmegen, The Netherlands, Institute of Chemical Kinetics and Combustion, Institutskaya Street 3, Novosibirsk 630090 Russia, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia, and Institute of Semiconductor Physics, Academician Lavrentiev Ave. 13, Novosibirsk 630090, Russia
| | - Sergei A. Kochubei
- Institute for Molecules and Materials, Radboud University Nijmegen, Heijendaalseweg 135, 6525 ED Nijmegen, The Netherlands, Institute of Chemical Kinetics and Combustion, Institutskaya Street 3, Novosibirsk 630090 Russia, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia, and Institute of Semiconductor Physics, Academician Lavrentiev Ave. 13, Novosibirsk 630090, Russia
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10
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Chichinin AI, Gericke KH, Kauczok S, Maul C. Imaging chemical reactions – 3D velocity mapping. INT REV PHYS CHEM 2009. [DOI: 10.1080/01442350903235045] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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Radenović DČ, van Roij AJ, Wu SM, Ter Meulen J, Parker DH, van der Loo MP, Janssen LM, Groenenboom GC. Photodissociation of vibrationally excited OH/OD radicals. Mol Phys 2008. [DOI: 10.1080/00268970801922783] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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12
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Zhang D, Abdel-hafiez A, Zhang B. Studies on the photodissociation dynamics of HI molecule within the A band range. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.09.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Wang F, Lu IC, Yuan K, Cheng Y, Wu M, Parker DH, Yang X. Photodissociation dynamics of HI and DI at 157nm. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.10.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Bi W, Xu X, Huang J, Xiao D, Tang Z, Zhu Q. Study on the (HI)
m
(H 2O)
n
Clusters by Photofragment Translational Spectroscopy and Ab-Initio Calculation. Z PHYS CHEM 2007. [DOI: 10.1524/zpch.2007.221.6.815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The photodissociation of the clusters (HI)
m
(H2O)
n
in the supersonic molecular beam has been investigated at 281.73 nm and 280.99 nm by photofragment translational spectroscopy (PTS). The translational energy distributions of the photofragment I*(2
P
1/2) show that the photodissociated species is mainly HI(H2O)
n
(n ≥ 4) clusters. In addition, the structures and the relative stability of (HI)
m
, (H2O)
n
and (HI)
m
(H2O)
n
(m = 1 ∼ 4, n = 1 ∼ 6) clusters have been obtained by ab initio calculation (the Density Functional Theory). The conclusion of the theoretical analysis is agreeable with the experimental results. So these results indicate that PTS combining theoretical calculation can be used as a new, indirect way to judge the composition of the clusters which are easy to be dissociated and difficult to be detected by mass spectroscopy.
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15
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Softley TP. Applications of molecular Rydberg states in chemical dynamics and spectroscopy. INT REV PHYS CHEM 2007. [DOI: 10.1080/01442350310001652940] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- T. P. Softley
- a Department of Chemistry , Chemistry Research Laboratory, University of Oxford , Mansfield Rd, Oxford OX1 3TA, UK
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16
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Ashfold MNR, Nahler NH, Orr-Ewing AJ, Vieuxmaire OPJ, Toomes RL, Kitsopoulos TN, Garcia IA, Chestakov DA, Wu SM, Parker DH. Imaging the dynamics of gas phase reactions. Phys Chem Chem Phys 2006; 8:26-53. [PMID: 16482242 DOI: 10.1039/b509304j] [Citation(s) in RCA: 240] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ion imaging methods are making ever greater impact on studies of gas phase molecular reaction dynamics. This article traces the evolution of the technique, highlights some of the more important breakthroughs with regards to improving image resolution and in image processing and analysis methods, and then proceeds to illustrate some of the many applications to which the technique is now being applied--most notably in studies of molecular photodissociation and of bimolecular reaction dynamics.
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17
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Velocity map ion imaging of H atoms from the dissociation of HCO ( A∼2A″) using Doppler-free multi-photon ionization. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.08.115] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Jodoin DN, Brown A. Photodissociation of HI and DI: Testing models for electronic structure via polarization of atomic photofragments. J Chem Phys 2005; 123:054301. [PMID: 16108633 DOI: 10.1063/1.1989327] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The photodissociation dynamics of HI and DI are examined using time-dependent wave-packet techniques. The orientation and alignment parameters aQ(K) (p) are determined as a function of photolysis energy for the resulting ground-state I(2P(3/2)) and excited-state I(2P(1/2)) atoms. The aQ(K) (p) parameters describe the coherent and incoherent contributions to the angular momentum distributions from the A 1pi(1), a 3pi(1), and t 3sigma(1) electronic states accessed by perpendicular excitation and the a 3pi(0+) state accessed by a parallel transition. The outcomes of the dynamics based on both shifted ab initio results and three empirical models for the potential-energy curves and transition dipole moments are compared and contrasted. It is demonstrated that experimental measurement of the aQ(K) (p) parameters for the excitation from the vibrational ground state (upsilon=0) would be able to distinguish between the available models for the HI potential-energy curves and transition dipole moments. The differences between the aQ(K) (p) parameters for the excitation from upsilon=0 stand in sharp contrast to the scalar properties, i.e., total cross section and I* branching fraction, which require experimental measurement of photodissociation from excited vibrational states (upsilon>0) to distinguish between the models.
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Affiliation(s)
- David N Jodoin
- Department of Chemistry, University of Alberta, Edmonton AB T6G 2G2, Canada
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19
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Brown A. Photodissociation of HI and DI: Polarization of atomic photofragments. J Chem Phys 2005; 122:84301. [PMID: 15836033 DOI: 10.1063/1.1850465] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The complete angular momentum distributions and vector correlation coefficients (orientation and alignment) of ground state I((2)P(32)) and excited state I((2)P(12)) atoms resulting from the photodissociation of HI have been computed as a function of photolysis energy. The orientation and alignment parameters a(Q) ((K))(p) that describe the coherent and incoherent contributions to the angular momentum distributions from the multiple electronic states accessed by parallel and perpendicular transitions are determined using a time-dependent wave packet treatment of the dissociation dynamics. The dynamics are based on potential energy curves and transition dipole moments that have been reported previously [R. J. LeRoy, G. T. Kraemer, and S. Manzhos, J. Chem. Phys. 117, 9353 (2002)] and used to successfully model the scalar (total cross section and branching fraction) and lowest order vector (anisotropy parameter beta) properties of the photodissociation. Predictions of the a(Q) ((K))(p), parameters for the isotopically substituted species DI are reported and contrasted to the analogous HI results. The resulting polarization for the corresponding H/D partners are also determined and demonstrate that both H and D atoms produced can be highly spin polarized. Comparison of these predictions for HI and DI with experimental measurement will provide the most stringent test of the current model for the electronic structure and the interpretation of the dissociation based on noncoupled excited state dynamics.
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Affiliation(s)
- Alex Brown
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
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20
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Aguirre F, Pratt ST. Photoionization and photodissociation dynamics of the B 1Σu+ and C 1Πu states of H2 and D2. J Chem Phys 2004; 121:9855-64. [PMID: 15549858 DOI: 10.1063/1.1810511] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The photoionization and photodissociation dynamics of H(2) and D(2) in selected rovibrational levels of the B (1)Sigma(u) (+) and C (1)Pi(u) states have been investigated by velocity map ion imaging. The selected rotational levels of the B (1)Sigma(u) (+) and C (1)Pi(u) states are prepared by three-photon excitation from the ground state. The absorption of fourth photon results in photoionization to produce H(2)(+) X (2)Sigma(g)(+) or photodissociation to produce a ground-state H(1s) atom and an excited H atom with n >or= 2. The H(2) (+) ion can be photodissociated by absorption of a fifth photon. The resulting H(+) or D(+) ion images provide information on the vibrational state dependence of the photodissociation angular distribution of the molecular ion. The excited H(n >or= 2) atoms produced by the neutral dissociation process can also be ionized by the absorption of a fifth photon. The resulting ion images provide insight into the excited state branching ratios and angular distributions of the neutral photodissociation process. While the experimental ion images contain information on both the ionic and neutral processes, these can be separated based on constraints imposed on the fragment translational energies. The angular distribution of the rings in the ion images indicates that the neutral dissociation of molecular hydrogen and its isotopes is quite complex, and involves coupling to both doubly excited electronic states and the dissociation continua of singly excited Rydberg states.
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Affiliation(s)
- F Aguirre
- Argonne National Laboratory, Argonne, Illinois 60439, USA
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21
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Cruse HA, Softley TP. Demonstration of the combination of slice imaging and Rydberg tagging for studies of photodissociation dynamics. J Chem Phys 2004; 121:4089-96. [PMID: 15332954 DOI: 10.1063/1.1779621] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The slice-imaging variant of photofragment ion imaging is combined with Rydberg tagging. The photodissociation of NO(2) at 355 nm is used as the test system and the NO fragments are Rydberg tagged by two-photon two-color excitation via the intermediate A (2)Sigma(+) state. Images obtained by this method are compared with ion images obtained in the same apparatus using the approach of Kitsopoulos and co-workers [Rev. Sci. Instrum. 72, 3848 (2001)]. Comparable resolution and angular distributions are obtained in the two cases. It is proposed that the method demonstrated here could provide a complementary approach to existing ion-imaging methods, especially where resonantly enhanced multiphoton ionization detection of fragments is problematic.
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Affiliation(s)
- H A Cruse
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
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Affiliation(s)
- Dave Townsend
- Department of Chemistry, SUNY Stony Brook, Stony Brook, New York 11794, Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, and Department of Chemistry, Wayne State University, Detroit, Michigan 48202
| | - Suk Kyoung Lee
- Department of Chemistry, SUNY Stony Brook, Stony Brook, New York 11794, Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, and Department of Chemistry, Wayne State University, Detroit, Michigan 48202
| | - Arthur G. Suits
- Department of Chemistry, SUNY Stony Brook, Stony Brook, New York 11794, Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, and Department of Chemistry, Wayne State University, Detroit, Michigan 48202
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Camden JP, Bechtel HA, Ankeny Brown DJ, Pomerantz AE, Zare RN, Le Roy RJ. Probing Excited Electronic States Using Vibrationally Mediated Photolysis: Application to Hydrogen Iodide. J Phys Chem A 2004. [DOI: 10.1021/jp049051z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Jon P. Camden
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | - Hans A. Bechtel
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | | | - Andrew E. Pomerantz
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | - Richard N. Zare
- Department of Chemistry, Stanford University, Stanford, California 94305-5080
| | - Robert J. Le Roy
- Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Slice imaging of H-atom photofragments: effects of the REMPI detection process on the observed velocity distribution. Chem Phys 2004. [DOI: 10.1016/j.chemphys.2003.11.038] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Le Roy RJ, Kraemer GT, Manzhos S. 1 potential, 2 potentials, 3 potentials–4: Untangling the UV photodissociation spectra of HI and DI. J Chem Phys 2002. [DOI: 10.1063/1.1513303] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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