1
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Cachón J, Recio P, Sorribes D, Marggi Poullain S, Rubio-Lago L, Bañares L. Structural Effects on the Energy Disposal and Atomic Photofragment Alignment for the Photodissociation of Alkyl Iodides at Excitation Wavelengths of 254 and 268 nm. J Phys Chem A 2024; 128:8312-8321. [PMID: 39298671 PMCID: PMC11457215 DOI: 10.1021/acs.jpca.4c02217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 09/04/2024] [Accepted: 09/05/2024] [Indexed: 09/22/2024]
Abstract
This work represents a step forward in the understanding of the widely studied photodynamics of alkyl iodides in the first absorption band. Ultraviolet (UV) photodissociation of several alkyl iodides (RI), specifically, a series of linear and ramified molecules with R = CnH2n+1, n = 1-4, at excitation wavelengths of 254 and 268 nm, which correspond to the maximum of the first absorption A-band, has been studied by combining resonance-enhanced multiphoton ionization (REMPI) detection of atomic photofragments I(2P3/2) and I*(2P1/2) and of pulsed slice imaging. Detailed examination of the total translational energy distributions of both atomic photofragments has been combined with stereodynamical information on the process obtained from the anisotropy β and alignment a02(∥) and Re[a12(∥, ⊥)] parameters to provide a description of the role played by the molecular structure of alkyl iodides in adiabatic and, especially, in nonadiabatic photodissociation dynamics through conical intersections or avoided crossings. The present results suggest that the linear structures couple more efficiently with the pure C-I reaction coordinate, whereas for the branched structures, the coupling with additional vibrational (bending) modes gains importance, showing the dissociation process a multidimensional character. In addition, a large degree of cofragment rotational alignment has been found for the small linear CH3I and C2H5I and, unexpectedly, for the branched t-C4H9I (C3v symmetry), whereas the rest of the alkyl iodides show low alignment parameters.
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Affiliation(s)
- Javier Cachón
- Departamento
de Química Física, Facultad de Ciencias
Químicas, Universidad Complutense
de Madrid, 28040 Madrid, Spain
| | - Pedro Recio
- Departamento
de Química Física, Facultad de Ciencias
Químicas, Universidad Complutense
de Madrid, 28040 Madrid, Spain
| | - David Sorribes
- Departamento
de Química Física, Facultad de Ciencias
Químicas, Universidad Complutense
de Madrid, 28040 Madrid, Spain
| | - Sonia Marggi Poullain
- Departamento
de Química Física, Facultad de Ciencias
Químicas, Universidad Complutense
de Madrid, 28040 Madrid, Spain
| | - Luis Rubio-Lago
- Departamento
de Química Física, Facultad de Ciencias
Químicas, Universidad Complutense
de Madrid, 28040 Madrid, Spain
| | - Luis Bañares
- Departamento
de Química Física, Facultad de Ciencias
Químicas, Universidad Complutense
de Madrid, 28040 Madrid, Spain
- Instituto
Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanoscience), C/Faraday, 9, 28049 Madrid, Spain
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2
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Sola IR, García-Vela A. Absolute control over the quantum yield of a photodissociation reaction mediated by nonadiabatic couplings. Chem Sci 2024:d4sc03235g. [PMID: 39220160 PMCID: PMC11350398 DOI: 10.1039/d4sc03235g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Accepted: 08/19/2024] [Indexed: 09/04/2024] Open
Abstract
Control of molecular reaction dynamics with laser pulses has been developed in the last decades. Among the different magnitudes whose control has been actively pursued, the branching ratio between different product channels constitutes the clearest signature of quantum control. In polyatomic molecules, the dynamics in the excited state is quagmired by non-adiabatic couplings, which are not directly affected by the laser, making control over the branching ratio a very demanding challenge. Here we present a control scheme for the CH3I photodissociation in the A band, that modifies the quantum yield of the two fragmentation channels of the process. The scheme relies on the optimized preparation of an initial superposition of vibrational states in the ground potential, which further interfere upon the excitation with a broad pump pulse. This interference can suppress any of the channels, regardless of its dominance, and can be achieved over the whole spectral range of the A band. Furthermore, it can be accomplished without strong fields or direct intervention during the dynamics in the excited states: the whole control is predetermined from the outset. The present work thus opens the possibility of extensive and universal control of the channel branching ratio in complex photodissociation processes.
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Affiliation(s)
- Ignacio R Sola
- Departamento de Química Física, Universidad Complutense de Madrid (and Unidad Asociada I+D+I al CSIC) 28040 Madrid Spain
| | - Alberto García-Vela
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas Serrano 123 28006 Madrid Spain
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3
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González-Vázquez J, García GA, Chicharro DV, Bañares L, Poullain SM. Evidencing an elusive conical intersection in the dissociative photoionization of methyl iodide. Chem Sci 2024; 15:3203-3213. [PMID: 38425510 PMCID: PMC10901492 DOI: 10.1039/d3sc04065h] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 12/23/2023] [Indexed: 03/02/2024] Open
Abstract
The valence-shell dissociative photoionization of methyl iodide (CH3I) is studied using double imaging photoelectron photoion coincidence (i2 PEPICO) spectroscopy in combination with highly-tunable synchrotron radiation from synchrotron SOLEIL. The experimental results are complemented by new high-level ab initio calculations of the potential energy curves of the relevant electronic states of the methyl iodide cation (CH3I+). An elusive conical intersection is found to mediate internal conversion from the initially populated first excited state, CH3I+(Ã2A1), into the ground cationic state, leading to the formation of methyl ions (CH3+). The reported threshold photoelectron spectrum for CH3+ reveals that the ν5 scissors vibrational mode promotes the access to this conical intersection and hence, the transfer of population. An intramolecular charge transfer takes place simultaneously, prior to dissociation. Upon photoionization into the second excited cationic state, CH3I+(B̃2E), a predissociative mechanism is shown to lead to the formation of atomic I+.
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Affiliation(s)
- Jesús González-Vázquez
- Departamento de Química, Facultad de Ciencias, Universidad Autónoma de Madrid Spain
- Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid 28049 Madrid Spain
| | - Gustavo A García
- Synchrotron SOLEIL L'Orme des Merisiers, St. Aubin, BP 48 91192 Gif-sur-Yvette France
| | - David V Chicharro
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid 28040 Madrid Spain
| | - Luis Bañares
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid 28040 Madrid Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience) Cantoblanco 28049 Madrid Spain
| | - Sonia Marggi Poullain
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid 28040 Madrid Spain
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4
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Cachón J, Recio P, Zanchet A, Marggi Poullain S, Bañares L. Photodissociation dynamics of methylamine in the blue edge of the A-band. II. The NH2 + CH3 channel. J Chem Phys 2023; 159:064302. [PMID: 37555612 DOI: 10.1063/5.0159855] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 07/20/2023] [Indexed: 08/10/2023] Open
Abstract
The photodissociation dynamics leading to the C-N bond cleavage in methylamine (CH3NH2) are investigated upon photoexcitation in the blue edge of the first absorption A-band, in the 198-204 nm range. Velocity map images of the generated methyl (CH3) fragment detected in specific vibrational modes, i.e., ν = 0, ν1 = 1, and ν2 = 1, through resonance enhanced multiphoton ionization, are presented along with the corresponding translational energy distributions and the angular analysis. The experimental results are complemented by high-level ab initio calculations of potential energy curves as a function of the C-N bond distance. While a similar single Boltzmann-type contribution is observed in all the translational energy distributions measured, the speed-dependent anisotropy parameter obtained through the angular analysis reveals the presence of two different mechanisms. Prompt dissociation through the conical intersection between the Ã1A' first excited state and the ground state located in the exit channel is, indeed, revealed as a minor channel. In contrast, slow dissociation on the ground state, presumably from frustrated N-H bond cleavage trajectories, constitutes the major reaction pathway leading to the methyl formation.
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Affiliation(s)
- Javier Cachón
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Pedro Recio
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Alexandre Zanchet
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain
| | - Sonia Marggi Poullain
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Luis Bañares
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience), Cantoblanco, 28049 Madrid, Spain
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5
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Recio P, Cachón J, Zanchet A, Marggi Poullain S, Bañares L. Photodissociation dynamics of methylamine in the blue edge of the A-band. I. The H-atom elimination channel. J Chem Phys 2023; 158:234304. [PMID: 37326159 DOI: 10.1063/5.0152993] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 05/30/2023] [Indexed: 06/17/2023] Open
Abstract
The photodissociation dynamics of methylamine (CH3NH2) upon excitation in the blue edge of the first absorption A-band, in the 198-203 nm range, are investigated by means of nanosecond pump-probe laser pulses and velocity map imaging combined with H(2S)-atom detection through resonance enhanced multiphoton ionization. The images and corresponding translational energy distributions for the H-atoms produced show three different contributions associated with three reaction pathways. The experimental results are complemented by high-level ab initio calculations. The potential energy curves computed as a function of the N-H and C-H bond distances allow us to draw a picture of the different mechanisms. Major dissociation occurs through N-H bond cleavage and it is triggered by an initial geometrical change, i.e., from a pyramidal configuration of the C-NH2 with respect to the N atom to a planar geometry. The molecule is then driven into a conical intersection (CI) seam where three outcomes can take place: first, threshold dissociation into the second dissociation limit, associated with the formation of CH3NH(Ã), is observed; second, direct dissociation after passage through the CI leading to the formation of ground state products; and third, internal conversion into the ground state well in advance to dissociation. While the two last pathways were previously reported at a variety of wavelengths in the 203-240 nm range, the former had not been observed before to the best of our knowledge. The role of the CI and the presence of an exit barrier in the excited state, which modify the dynamics leading the two last mechanisms, are discussed considering the different excitation energies used.
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Affiliation(s)
- Pedro Recio
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Javier Cachón
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Alexandre Zanchet
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain
| | - Sonia Marggi Poullain
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Luis Bañares
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience), Cantoblanco, 28049 Madrid, Spain
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6
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Nam Y, Cho D, Gu B, Rouxel JR, Keefer D, Govind N, Mukamel S. Time-Evolving Chirality Loss in Molecular Photodissociation Monitored by X-ray Circular Dichroism Spectroscopy. J Am Chem Soc 2022; 144:20400-20410. [DOI: 10.1021/jacs.2c08458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Yeonsig Nam
- Department of Chemistry, University of California, Irvine, Irvine, California92697, United States
| | - Daeheum Cho
- Departments of Chemistry, Kyungpook National University, Daegu41566, South Korea
| | - Bing Gu
- Department of Chemistry, University of California, Irvine, Irvine, California92697, United States
| | - Jérémy R. Rouxel
- UJM-Saint-Étienne, CNRS, Graduate School Optics Institute, Laboratoire Hubert Curien UMR 5516, University Lyon, Saint-Étienne42023, France
| | - Daniel Keefer
- Department of Chemistry, University of California, Irvine, Irvine, California92697, United States
| | - Niranjan Govind
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington99354, United States
| | - Shaul Mukamel
- Department of Chemistry, University of California, Irvine, Irvine, California92697, United States
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7
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Weike N, Chanut E, Hoppe H, Eisfeld W. Development of a fully coupled diabatic spin-orbit model for the photodissociation of phenyl iodide. J Chem Phys 2022; 156:224109. [PMID: 35705416 DOI: 10.1063/5.0088205] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The theoretical treatment of the quantum dynamics of the phenyl iodide photodissociation requires an accurate analytical potential energy surface (PES) model. This model must also account for spin-orbit (SO) coupling. This study is the first step to construct accurate SO coupled PESs, namely, for the C-I dissociation coordinate. The model is based on the Effective Relativistic Coupling by Asymptotic Representation (ERCAR) method developed over the past ten years. The SO-free Hamiltonian is represented in an asymptotic diabatic basis and then combined with an atomic effective relativistic coupling operator determined analytically. In contrast to the previously studied cases (HI, CH3I), the diabatic basis states are due to excitations in the phenyl fragment rather than the iodine atom. An accurate analytical model of the ab initio reference data is determined in two steps. The first step is a simple reference model describing the data qualitatively. This reference model is corrected through a trained artificial neural-network to achieve high accuracy. The SO-free and the fine structure states resulting from this ERCAR model are discussed extensively in the context of the photodissociation.
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Affiliation(s)
- Nicole Weike
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Emma Chanut
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Hannes Hoppe
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Wolfgang Eisfeld
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
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8
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Marggi Poullain S, Rubio-Lago L, Chicharro DV, Boullagui A, Zanchet A, Yazidi O, García-Vela A, Bañares L. Imaging the elusive C–C bond dissociation channel of photoexcited ethyl radical. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1984598] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Sonia Marggi Poullain
- Facultad de Ciencias Químicas, Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Universidad Complutense de Madrid, Madrid, Spain
| | - Luis Rubio-Lago
- Facultad de Ciencias Químicas, Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Universidad Complutense de Madrid, Madrid, Spain
| | - David V. Chicharro
- Facultad de Ciencias Químicas, Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Universidad Complutense de Madrid, Madrid, Spain
| | - Aymen Boullagui
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Madrid, Spain
- Laboratoire de Spectroscopie Atomique, Moléculaire et Applications-LSAMA LR01ES09, Faculté des Sciences de Tunis, Université de Tunis El Manar, Tunis, Tunisia
| | - Alexandre Zanchet
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Ounaies Yazidi
- Laboratoire de Spectroscopie Atomique, Moléculaire et Applications-LSAMA LR01ES09, Faculté des Sciences de Tunis, Université de Tunis El Manar, Tunis, Tunisia
| | - Alberto García-Vela
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Luis Bañares
- Facultad de Ciencias Químicas, Departamento de Química Física (Unidad Asociada I+D+i al CSIC), Universidad Complutense de Madrid, Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience), Madrid, Spain
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9
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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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10
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Vinklárek IS, Suchan J, Rakovský J, Moriová K, Poterya V, Slavíček P, Fárník M. Energy partitioning and spin-orbit effects in the photodissociation of higher chloroalkanes. Phys Chem Chem Phys 2021; 23:14340-14351. [PMID: 34169306 DOI: 10.1039/d1cp01371h] [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 investigate the photodissociation dynamics of the C-Cl bond in chloroalkanes CH3Cl, n-C3H7Cl, i-C3H7Cl, n-C5H11Cl, combining velocity map imaging (VMI) experiment and direct ab initio dynamical simulations. The Cl fragment kinetic energy distributions (KEDs) from the VMI experiment exhibit a single peak with maximum close to 0.8 eV, irrespective of the alkyl chain length and C-Cl bond position. In contrary to CH3Cl, where less than 10% of the available energy is deposited into the internal excitation of the CH3 fragment, for all higher chloroalkanes around 40% to 60% of the available energy goes into the alkyl fragment excitation. We apply the classical hard spheres and spectator model to explain the energy partitioning, and compare the classical approach with direct ab initio dynamics simulations. The alkyl chain appears to be a soft, energy absorbing unit. We further investigate the role of the spin-orbit effects on the excitation and dynamics. Combining our experimental data with theory allows us to derive the probability of the direct absorption into the triplet electronic state as well as the probabilities for intersystem crossing. The results indicate an increasing direct absorption into the triplet state with increasing alkyl chain length.
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Affiliation(s)
- Ivo S Vinklárek
- J. Heyrovský Institute of Physical Chemistry, v.v.i., The Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
| | - Jiří Suchan
- University of Chemistry and Technology, 166 28 Prague 6, Czech Republic.
| | - Jozef Rakovský
- J. Heyrovský Institute of Physical Chemistry, v.v.i., The Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
| | - Kamila Moriová
- J. Heyrovský Institute of Physical Chemistry, v.v.i., The Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
| | - Viktoriya Poterya
- J. Heyrovský Institute of Physical Chemistry, v.v.i., The Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
| | - Petr Slavíček
- University of Chemistry and Technology, 166 28 Prague 6, Czech Republic.
| | - Michal Fárník
- J. Heyrovský Institute of Physical Chemistry, v.v.i., The Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
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11
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Allum F, Mason R, Burt M, Slater CS, Squires E, Winter B, Brouard M. Post extraction inversion slice imaging for 3D velocity map imaging experiments. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1842531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Felix Allum
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Robert Mason
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Michael Burt
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Craig S. Slater
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Eleanor Squires
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Benjamin Winter
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Mark Brouard
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
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12
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Vinklárek IS, Rakovský J, Poterya V, Fárník M. Different Dynamics of CH3 and Cl Fragments from Photodissociation of CH3Cl in Clusters. J Phys Chem A 2020; 124:7633-7643. [DOI: 10.1021/acs.jpca.0c05926] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ivo S. Vinklárek
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
- Faculty of Mathematics and PhysicsCharles UniversityKe Karlovu 3121 16Prague 2Czech Republic
| | - Jozef Rakovský
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - Viktoriya Poterya
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - Michal Fárník
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
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13
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González MG, Marggi Poullain S, Rubio-Lago L, Bañares L. Velocity map imaging study of the photodissociation dynamics of the allyl radical. Phys Chem Chem Phys 2020; 22:5995-6003. [PMID: 32123886 DOI: 10.1039/c9cp04758a] [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
The photodissociation of the allyl radical (CH2[double bond, length as m-dash]CH-CH2˙) following excitation between 216 and 243 nm has been investigated employing velocity map imaging in conjunction with resonance enhanced multiphoton ionization to detect the hydrogen atom and CH3(ν = 0) produced. The translational energy distributions for the two fragments are reported and analyzed along with the corresponding fragment ion angular distributions. The results are discussed in terms of the different reactions pathways characterizing the hydrogen atom elimination and the minor methyl formation. On one hand, the angular analysis provides evidence of an additional mechanism, not reported before, leading to prompt dissociation and fast hydrogen atoms. On the other hand, the methyl elimination channel has been characterized as a function of the excitation energy and the contribution of three reaction pathways: single 1,3-hydrogen shift, double 1,2-hydrogen shift and through the formation of vinylidene have been discussed. Contrary to previous predictions, the vinylidene channel, which plays a significant role at lower energies, seems to vanish following excitation on the E[combining tilde]2B1(3px) excited state at λ≤ 230 nm.
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Affiliation(s)
- Marta G González
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
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14
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Matthíasson K, Koumarianou G, Jiang MX, Glodic P, Samartzis PC, Kvaran Á. Formation of highly excited iodine atoms from multiphoton excitation of CH 3I. Phys Chem Chem Phys 2020; 22:4984-4992. [PMID: 32083618 DOI: 10.1039/c9cp06242d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mass resolved REMPI spectra, as well as CH3+and I+ ion and photoelectron images, were recorded for two-photon resonant excitations of CH3I via s, p and d Rydberg states (CH3I**) in the excitation region of 55 700 to 70 000 cm-1. Photoelectron (PE) and ion kinetic energy release spectra (KERs) were derived from the images. The data revealed that after the two-photon resonant excitation, an additional photon is absorbed to form one or more superexcited state(s) (CH3I#), followed by branching into three pathways. The major one is the dissociation of CH3I# to form excited Rydberg states of iodine atoms (I**) along with CH3(X), a phenomenon not commonly observed in methyl halides. The second (minor) pathway involves autoionization of CH3I# towards CH3I+(X), which absorbs another photon to form CH3+ along with I/I* and the third one (minor) is CH3I# dissociation towards the ion pair, CH3+ + I-, prior to I- electron ejection. Furthermore, one-photon non-resonant dissociation of CH3I to form CH3(X) and I/I* prior to three-photon ionization of the fragments is also detected.
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15
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Murillo-Sánchez ML, González-Vázquez J, Corrales ME, de Nalda R, Martínez-Núñez E, García-Vela A, Bañares L. Femtochemistry under scrutiny: Clocking state-resolved channels in the photodissociation of CH3I in the A-band. J Chem Phys 2020; 152:014304. [DOI: 10.1063/1.5134473] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Marta L. Murillo-Sánchez
- Departamento de Química Física, Facultad de Ciencias Químicas (Unidad Asociada de I+D+i al Consejo Superior de Investigaciones Científicas), Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Jesús González-Vázquez
- Departamento de Química and Institute for Advanced Research in Chemical Sciences (IAdChem), Módulo 13, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - María E. Corrales
- Departamento de Química Física, Facultad de Ciencias Químicas (Unidad Asociada de I+D+i al Consejo Superior de Investigaciones Científicas), Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Rebeca de Nalda
- Instituto de Química Física Rocasolano, CSIC, C/ Serrano 119, 28006 Madrid, Spain
| | - Emilio Martínez-Núñez
- Departamento de Química Física, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | | | - Luis Bañares
- Departamento de Química Física, Facultad de Ciencias Químicas (Unidad Asociada de I+D+i al Consejo Superior de Investigaciones Científicas), Universidad Complutense de Madrid, 28040 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience), Cantoblanco, 28049 Madrid, Spain
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16
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Warne EM, Downes-Ward B, Woodhouse J, Parkes MA, Springate E, Pearcy PAJ, Zhang Y, Karras G, Wyatt AS, Chapman RT, Minns RS. Photodissociation dynamics of methyl iodide probed using femtosecond extreme ultraviolet photoelectron spectroscopy. Phys Chem Chem Phys 2020; 22:25695-25703. [DOI: 10.1039/d0cp03478a] [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
Femtosecond pump–probe photoelectron spectroscopy measurements using an extreme ultraviolet probe have been made on the photodissociation dynamics of UV (269 nm) excited CH3I.
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Affiliation(s)
- Emily M. Warne
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
| | | | - Joanne Woodhouse
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
| | | | - Emma Springate
- Central Laser Facility
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | | | - Yu Zhang
- Central Laser Facility
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | - Gabriel Karras
- Central Laser Facility
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | - Adam S. Wyatt
- Central Laser Facility
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | | | - Russell S. Minns
- School of Chemistry
- University of Southampton
- Southampton SO17 1BJ
- UK
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17
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Marggi Poullain S, Chicharro DV, Zanchet A, Rubio-Lago L, García-Vela A, Bañares L. The 3s versus 3p Rydberg state photodissociation dynamics of the ethyl radical. Phys Chem Chem Phys 2019; 21:23017-23025. [PMID: 31599893 DOI: 10.1039/c9cp04273c] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photodissociation dynamics of the ethyl radical following excitation into the 3s and 3p Rydberg states are revisited in a joint experimental and theoretical study. Two different methods to produce the ethyl radical, pyrolysis and in situ photolysis, are employed in order to modify the initial ro-vibrational energy distribution characterizing the ethyl radical beam. H-atom velocity map images following excitation of the radical at 243 nm and at 201 nm are presented and discussed along with ab initio potential energy curves focussing on the bridged C2v geometry. The reported results show that the dynamics following excitation to the 3s Rydberg state is insensitive to the initial internal energy of the parent radical, in contrast to the dynamics on the 3p Rydberg state, which is strongly modified. The role of the bridged C2v geometry on both photodynamics is highlighted and discussed.
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Affiliation(s)
- Sonia Marggi Poullain
- Departamento de Química, Módulo 13, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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18
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Chicharro DV, Marggi Poullain S, Rubio-Lago L, Bañares L. Photodissociation Dynamics and Stereodynamics of Methyl Mercaptan and Dimethyl Sulfide from the Second Absorption Band at 201 and 210 nm. J Phys Chem A 2019; 123:8552-8561. [PMID: 31525928 DOI: 10.1021/acs.jpca.9b07242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The role of promoting and spectator modes vs energy randomization in nonadiabatic dynamics is interrogated in the photodissociation of methyl mercaptan, CH3SH, and dimethyl sulfide, CH3SCH3 or DMS, in the second absorption band. The primary CH3(ν) radicals produced in the dissociation of both systems at 210 nm have been resonantly detected in slice-imaging experiments, and the corresponding translational energy and angular distributions have been obtained. The stereodynamical information provided by Dixon's bipolar moments in conjunction with the energy partitioning among the different degrees of freedom of the primary CH3(ν) products offers a panoramic picture of the photodissociation process of both systems. The remarkable similitude found between the two systems related to both vector correlations and internal energy content of the corresponding counterparts-SH for methyl mercaptan and SCH3 for DMS-indicates that despite the diabaticity of the process, no efficient energy randomization of the available energy takes place. More specifically, only the parent vibrational modes whose participation in the initial absorption step is imposed by the conical intersection-i.e., the promoting modes-are adiabatically preserved during the process, while the rest of the vibrational modes play the spectator role. The results for both molecules at 210 nm are complemented with experiments carried out for DMS at 201 nm to explore the internal mechanism of the conical intersection in different zones of the absorption region.
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Affiliation(s)
- David V Chicharro
- Departamento de Química Física, Facultad de Ciencias Químicas , Universidad Complutense de Madrid , 28040 Madrid , Spain
| | - Sonia Marggi Poullain
- Departamento de Química, Módulo 13, Facultad de Ciencias , Universidad Autónoma de Madrid , 28049 Madrid , Spain
| | - Luis Rubio-Lago
- Departamento de Química Física, Facultad de Ciencias Químicas , Universidad Complutense de Madrid , 28040 Madrid , Spain
| | - Luis Bañares
- Departamento de Química Física, Facultad de Ciencias Químicas , Universidad Complutense de Madrid , 28040 Madrid , Spain.,Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience) , Cantoblanco, 28049 Madrid , Spain
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19
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Chicharro DV, Poullain SM, Zanchet A, Bouallagui A, García-Vela A, Senent ML, Rubio-Lago L, Bañares L. Site-specific hydrogen-atom elimination in photoexcited ethyl radical. Chem Sci 2019; 10:6494-6502. [PMID: 31341601 PMCID: PMC6610558 DOI: 10.1039/c9sc02140j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 05/22/2019] [Indexed: 12/03/2022] Open
Abstract
The photochemistry of the ethyl radical following excitation to the 3p Rydberg state is investigated in a joint experimental and theoretical study. Velocity map images for hydrogen atoms detected from photoexcited isotopologues CH3CH2, CH3CD2 and CD3CH2 at ∼201 nm, are discussed along with high-level ab initio electronic structure calculations of potential energy curves and non-adiabatic coupling matrix elements (NACME). A novel mechanism governed by a conical intersection allowing prompt site-specific hydrogen-atom elimination is presented and discussed. For this mechanism to occur, an initial ro-vibrational excitation is allocated to the radical permitting to access this reaction pathway and thus to control the ethyl photochemistry. While hydrogen-atom elimination from cold ethyl radicals occurs through internal conversion into lower electronic states followed by slow statistical dissociation, prompt site-specific Cα elimination into CH3CH + H, occurring through a fast non-adiabatic crossing to a valence bound state followed by dissociation through a conical intersection, is accessed by means of an initial ro-vibrational energy content into the radical. The role of a particularly effective vibrational promoting mode in this prompt photochemical reaction pathway is discussed.
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Affiliation(s)
- David V Chicharro
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC) , Facultad de Ciencias Químicas , Universidad Complutense de Madrid , 28040 Madrid , Spain . ; Tel: +34 913944228
| | - Sonia Marggi Poullain
- Departamento de Química , Módulo 13 , Facultad de Ciencias , Universidad Autónoma de Madrid , 28049 Madrid , Spain
| | - Alexandre Zanchet
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC) , Facultad de Ciencias Químicas , Universidad Complutense de Madrid , 28040 Madrid , Spain . ; Tel: +34 913944228
- Instituto de Física Fundamental , Consejo Superior de Investigaciones Científicas , C/ Serrano, 123 , 28006 Madrid , Spain
| | - Aymen Bouallagui
- Instituto de Física Fundamental , Consejo Superior de Investigaciones Científicas , C/ Serrano, 123 , 28006 Madrid , Spain
- Laboratoire de Spectroscopie Atomique, Moléculaire et Applications-LSAMA LR01ES09 , Faculté des Sciences de Tunis , Université de Tunis El Manar , 2092 , Tunis , Tunisia
| | - Alberto García-Vela
- Instituto de Física Fundamental , Consejo Superior de Investigaciones Científicas , C/ Serrano, 123 , 28006 Madrid , Spain
| | - María L Senent
- Departamento de Química y Física Teóricas , Instituto de Estructura de la Materia , Consejo Superior de Investigaciones Científicas , C/ Serrano, 121 , 28006 Madrid , Spain
| | - Luis Rubio-Lago
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC) , Facultad de Ciencias Químicas , Universidad Complutense de Madrid , 28040 Madrid , Spain . ; Tel: +34 913944228
| | - Luis Bañares
- Departamento de Química Física (Unidad Asociada I+D+i al CSIC) , Facultad de Ciencias Químicas , Universidad Complutense de Madrid , 28040 Madrid , Spain . ; Tel: +34 913944228
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20
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Marggi Poullain S, Recio P, Chicharro DV, Rubio-Lago L, González-Vázquez J, Bañares L. Dynamics of the photodissociation of ethyl iodide from the origin of the B band. A slice imaging study. Phys Chem Chem Phys 2019; 21:14250-14260. [PMID: 30565605 DOI: 10.1039/c8cp06482b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photodissociation dynamics and stereodynamics of ethyl iodide from the origin of the second absorption B-band have been investigated combining pulsed slicFe imaging with resonance enhanced multiphoton ionization (REMPI) detection of all fragments, I(2P3/2), I*(2P1/2) and C2H5. The I*(2P1/2) atom action spectrum recorded as a function of the excitation wavelength permits one to identify and select the 0 origin of this band at 201.19 nm (49 704 cm-1). Translational energy distributions and angular distributions for all fragments and semiclassical Dixon's bipolar moments for the C2H5 fragment are presented and discussed along with high-level ab initio calculations of potential energy curves as a function of the C-I distance. A predissociative mechanism governs the dynamics where in a first step a bound Rydberg state corresponding to the 5pπI→ 6sI transition is populated by the 201.19 nm-photon absorption. A curve crossing with a repulsive state located within the Franck-Condon geometry leads to direct dissociation into the major channel C2H5 + I*(2P1/2). A small amount of I(2P3/2) atoms is nevertheless observed and presumably attributed to a second curve crossing with a repulsive state from the A-band.
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Affiliation(s)
- Sonia Marggi Poullain
- Departamento de Química, Módulo 13, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Pedro Recio
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
| | - David V Chicharro
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
| | - Luis Rubio-Lago
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
| | - Jesús González-Vázquez
- Departamento de Química, Módulo 13, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain and Institute for Advanced Research in Chemical Sciences (IAdChem), Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Luis Bañares
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
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21
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Hafliðason A, Glodic P, Koumarianou G, Samartzis PC, Kvaran Á. Two-color studies of CH 3Br excitation dynamics with MPI and slice imaging. Phys Chem Chem Phys 2019; 21:10391-10401. [PMID: 31065628 DOI: 10.1039/c8cp06376a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two-color pump-probe experiments were performed to explore the multiphoton dynamics of CH3Br at high excitation energies of 8-10 eV, involving two-photon resonant excitations to a number of np and nd Rydberg states (pump) followed by REMPI detection (probe) of the Br, Br* and CH3(X) photoproducts. Slice images of Br+ and CH3+ ions were recorded in pump-only, probe-only and pump and probe experiments. Kinetic-energy release spectra (KERs), as well as spatial anisotropy parameters, were extracted from the images to identify the processes and the dynamics involved. Predissociation channels, following the two-photon resonant excitations and non-resonant photodissociation forming CH3(X) and Br/Br*, were identified and characterized. Furthermore, the probe excitations for CH3(X) involved near-resonant excitations to lower energy 5s Rydberg states of CH3Br. In three-photon excitation processes, a striking contrast is seen between excitations via the p/d and the s Rydberg states. Involvement of high-energy interactions between Rydberg and ion-pair states is identified.
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Affiliation(s)
- Arnar Hafliðason
- Science Institute, University of Iceland, Dunhagi 3, 107 Reykjavík, Iceland.
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22
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Serrano-Jiménez A, Bañares L, García-Vela A. Weak-field coherent control of photodissociation in polyatomic molecules. Phys Chem Chem Phys 2019; 21:7885-7893. [PMID: 30916089 DOI: 10.1039/c9cp01214a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A coherent control scheme is suggested to modify the output of photodissociation in a polyatomic system. The performance of the scheme is illustrated by applying it to the ultrafast photodissociation of CH3I in the A-band. The control scheme uses a pump laser weak field that combines two pulses of a few femtoseconds delayed in time. By varying the time delay between the pulses, the shape of the laser field spectral profile is modulated, which causes a change in the initial relative populations excited by the pump laser to the different electronic states involved in the photodissociation. Such a change in the relative populations produces different photodissociation outputs, which is the basis of the control achieved. The degree of control obtained over different photodissociation observables, like the branching ratio between the two dissociation channels of CH3I yielding I(2P3/2) and I*(2P1/2) and the fragment angular distributions associated with each channel, is investigated. These magnitudes are found to oscillate strongly with the time delay, with the branching ratio changing by factors between two and three. Substantial variations of the angular distributions also indicate that the scheme provides a high degree of control. Experimental application of the scheme to general polyatomic photodissociation processes should be straightforward.
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Affiliation(s)
- A Serrano-Jiménez
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain.
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23
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Malakar Y, Pearson WL, Zohrabi M, Kaderiya B, P. KR, Ziaee F, Xue S, Le AT, Ben-Itzhak I, Rolles D, Rudenko A. Time-resolved imaging of bound and dissociating nuclear wave packets in strong-field ionized iodomethane. Phys Chem Chem Phys 2019; 21:14090-14102. [DOI: 10.1039/c8cp07032f] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the results of a time-resolved coincident ion momentum imaging experiment probing nuclear wave packet dynamics in the strong-field ionization and dissociation of iodomethane (CH3I).
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24
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Warne EM, Downes-Ward B, Woodhouse J, Parkes MA, Bellshaw D, Springate E, Majchrzak P, Zhang Y, Karras G, Wyatt AS, Chapman RT, Kirrander A, Minns RS. Photodissociation dynamics of CH3I probed via multiphoton ionisation photoelectron spectroscopy. Phys Chem Chem Phys 2019; 21:11142-11149. [DOI: 10.1039/c9cp01477b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Femtosecond photoelectron spectroscopy measurements of dissociation CH3I show complex dynamics in the high energy region of absorption band A.
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25
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Allum F, Burt M, Amini K, Boll R, Köckert H, Olshin PK, Bari S, Bomme C, Brauße F, Cunha de Miranda B, Düsterer S, Erk B, Géléoc M, Geneaux R, Gentleman AS, Goldsztejn G, Guillemin R, Holland DMP, Ismail I, Johnsson P, Journel L, Küpper J, Lahl J, Lee JWL, Maclot S, Mackenzie SR, Manschwetus B, Mereshchenko AS, Mason R, Palaudoux J, Piancastelli MN, Penent F, Rompotis D, Rouzée A, Ruchon T, Rudenko A, Savelyev E, Simon M, Schirmel N, Stapelfeldt H, Techert S, Travnikova O, Trippel S, Underwood JG, Vallance C, Wiese J, Ziaee F, Brouard M, Marchenko T, Rolles D. Coulomb explosion imaging of CH3I and CH2ClI photodissociation dynamics. J Chem Phys 2018; 149:204313. [DOI: 10.1063/1.5041381] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Felix Allum
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Michael Burt
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Kasra Amini
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Rebecca Boll
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Hansjochen Köckert
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Pavel K. Olshin
- Saint-Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Sadia Bari
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Cédric Bomme
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Felix Brauße
- Max-Born-Institut, Max-Born-Straße 2A, 12489 Berlin, Germany
| | - Barbara Cunha de Miranda
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
| | - Stefan Düsterer
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Benjamin Erk
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Marie Géléoc
- LIDYL, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
| | - Romain Geneaux
- LIDYL, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
| | - Alexander S. Gentleman
- The Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom
| | | | - Renaud Guillemin
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
| | - David M. P. Holland
- Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, United Kingdom
| | - Iyas Ismail
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
| | - Per Johnsson
- Department of Physics, Lund University, 22100 Lund, Sweden
| | - Loïc Journel
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
| | - Jochen Küpper
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Physics, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Chemistry, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Jan Lahl
- Department of Physics, Lund University, 22100 Lund, Sweden
| | - Jason W. L. Lee
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Sylvain Maclot
- Department of Physics, Lund University, 22100 Lund, Sweden
| | - Stuart R. Mackenzie
- The Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom
| | - Bastian Manschwetus
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Andrey S. Mereshchenko
- Saint-Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Robert Mason
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Jérôme Palaudoux
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
| | - Maria Novella Piancastelli
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala, Sweden
| | - Francis Penent
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
| | - Dimitrios Rompotis
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Arnaud Rouzée
- Max-Born-Institut, Max-Born-Straße 2A, 12489 Berlin, Germany
| | - Thierry Ruchon
- LIDYL, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 Gif-sur-Yvette, France
| | - Artem Rudenko
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - Evgeny Savelyev
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Marc Simon
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
| | - Nora Schirmel
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Henrik Stapelfeldt
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Simone Techert
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Institute of X-ray Physics, University of Göttingen, 37077 Göttingen, Germany
| | - Oksana Travnikova
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
| | - Sebastian Trippel
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Jonathan G. Underwood
- Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Claire Vallance
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Joss Wiese
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- Department of Chemistry, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
| | - Farzaneh Ziaee
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - Mark Brouard
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Tatiana Marchenko
- Sorbonne Université, CNRS, Laboratoire de Chimie Physique—Matière et Rayonnement, LCPMR, F-75005 Paris, France
| | - Daniel Rolles
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
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Kamiya M, Taketsugu T. Ab initio surface hopping excited-state molecular dynamics approach on the basis of spin-orbit coupled states: An application to the A-band photodissociation of CH 3 I. J Comput Chem 2018; 40:456-463. [PMID: 30451310 DOI: 10.1002/jcc.25727] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 09/21/2018] [Accepted: 09/22/2018] [Indexed: 11/06/2022]
Abstract
Ab initio molecular dynamics approach has been extended to multi-state dynamics on the basis of the spin-orbit coupled electronic states that are obtained through diagonalization of the spin-orbit coupling matrix with the multi-state second-order multireference perturbation theory energies in diagonal elements and the spin-orbit coupling terms at the state-averaged complete active space self-consistent field level in off-diagonal elements. Nonadiabatic transitions over the spin-orbit coupled states were taken into account explicitly by a surface hopping scheme with utilizing the nonadiabatic coupling terms calculated by numerical differentiation of the spin-orbit coupled wavefunctions and analytical nonadiabatic coupling terms. The present method was applied to the A-band photodissociation of methyl iodide, CH3 I + hv → CH3 + I (2 P3/2 )/I* (2 P1/2 ), for which a pioneering theoretical work was reported by Amatatsu, Yabushita, and Morokuma. The present results reproduced well the experimental branching ratio and energy distributions in the dissociative products. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Muneaki Kamiya
- Faculty of Regional Studies, Gifu University, Gifu, 501-1132, Japan
| | - Tetsuya Taketsugu
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
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27
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Li F, Ma Y, Liu J, Wang F. Parent bending effects on nonadiabatic transition dynamics: Isotopomer-resolved imaging of photodissociation of CF 3Br at two source temperatures. J Chem Phys 2018; 149:124303. [PMID: 30278672 DOI: 10.1063/1.5047927] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nonadiabatic transition between electronic states plays a critical role in the photodissociation of the CX3Y (X = H and F; Y = Cl, Br, and I) system, and the transition probability was considered to be closely related to the X-C-Y bending motion. Hereby the effect of F-C-Br bending vibration on the nonadiabatic transition dynamics is studied by time-sliced ion velocity imaging of Br(2P1/2,3/2) isotopomers produced from the photodissociation of title molecules at two source temperatures, 298 K and 473 K, respectively. At the photolysis wavelength 234 nm, the anisotropy parameter (β) of the Br(2P3/2) products decreases from 1.3 at 298 K to 0.9 at 473 K, while the β of Br(2P1/2) remains at almost 2 at two temperatures, indicating the significant effect of bending excitation on the ground channel. Two nonadiabatic dissociation pathways are suggested in the Br(2P3/2) channel. One of them is the parallel excitation from the ground state to the 3 Q 0 state in C3V symmetry, and then transition to the 1 Q 1 state via conical intersection, and the other is the perpendicular excitation to the 3A' state in Cs symmetry and then decomposition along this state in the presence of the avoided crossing between 3A' and 4A' states. Closely related to the F-C-Br bending vibration of CF3Br is the latter transition.
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Affiliation(s)
- Fangfang Li
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Centre of Chemistry for Energy Materials, Fudan University, Shanghai 200433, People's Republic of China
| | - Yujie Ma
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Centre of Chemistry for Energy Materials, Fudan University, Shanghai 200433, People's Republic of China
| | - Jiaxing Liu
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Centre of Chemistry for Energy Materials, Fudan University, Shanghai 200433, People's Republic of China
| | - Fengyan Wang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Collaborative Innovation Centre of Chemistry for Energy Materials, Fudan University, Shanghai 200433, People's Republic of China
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28
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Wittenbrink N, Eisfeld W. Extension of the effective relativistic coupling by asymptotic representation (ERCAR) approach to multi-dimensional potential energy surfaces: 3D model for CH3I. J Chem Phys 2018. [DOI: 10.1063/1.5011757] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Nils Wittenbrink
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Wolfgang Eisfeld
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
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29
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Han YC, Tsai PY, Bowman JM, Lin KC. Photodissociation of CH 3CHO at 248 nm: identification of the channels of roaming, triple fragmentation and the transition state. Phys Chem Chem Phys 2018; 19:18628-18634. [PMID: 28692092 DOI: 10.1039/c7cp02952g] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Quasi-classical trajectory (QCT) calculations are performed on the molecular products CO + CH4via the tight transition state (TS) and global minimum configurations. With the aid of this theoretical evidence, we have re-examined the experimental results published previously to clarify the controversial issue of photodissociation dynamics of CH3CHO at 248 nm. For the CO (v = 0 and 1) bimodal rotational distributions obtained previously [K.-C. Hung, P.-Y. Tsai, H.-K. Li, and K.-C. Lin, J. Chem. Phys., 2014, 140, 064313], the low-rotational (J) component is re-assigned to the contribution of triple fragmentation (H + CO + CH3), whereas the high-J component is ascribed to the CH3-roaming pathway. The H-roaming pathway is not found in the calculations. Further, the QCT results have confirmed that the CO vibrational population especially at higher states and the low-energy component of CH4 vibrational bimodality obtained experimentally are mainly produced following the TS pathway, which has never been identified before. While taking into account both the theoretical and experimental results, the ratio of the molecular products (CO(v = 1) + CH4) obtained by the triple fragmentation/roaming/TS processes is evaluated to be 0.23 : 1 : 0.29.
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Affiliation(s)
- Yong-Chang Han
- Department of Physics, Dalian University of Technology, Dalian, P. R. China.
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30
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Marggi Poullain S, Chicharro DV, Navarro E, Rubio-Lago L, González-Vázquez J, Bañares L. Photodissociation dynamics of bromoiodomethane from the first and second absorption bands. A combined velocity map and slice imaging study. Phys Chem Chem Phys 2018; 20:3490-3503. [PMID: 29335697 DOI: 10.1039/c7cp07077b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ion imaging is applied to disentangle the selective bond cleavage in the photodissociation of bromoiodomethane from the two first absorption bands.
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Affiliation(s)
- Sonia Marggi Poullain
- Departamento de Qumica Fsica I
- Facultad de Ciencias Qumicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - David V. Chicharro
- Departamento de Qumica Fsica I
- Facultad de Ciencias Qumicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - Eduardo Navarro
- Departamento de Qumica Fsica I
- Facultad de Ciencias Qumicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - Luis Rubio-Lago
- Departamento de Qumica Fsica I
- Facultad de Ciencias Qumicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - Jesús González-Vázquez
- Departamento de Qumica
- Módulo 13
- Facultad de Ciencias
- Universidad Autónoma de Madrid
- 28049 Madrid
| | - Luis Bañares
- Departamento de Qumica Fsica I
- Facultad de Ciencias Qumicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
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31
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Murillo-Sánchez ML, Marggi Poullain S, Bajo JJ, Corrales ME, González-Vázquez J, Solá IR, Bañares L. Halogen-atom effect on the ultrafast photodissociation dynamics of the dihalomethanes CH2ICl and CH2BrI. Phys Chem Chem Phys 2018; 20:20766-20778. [PMID: 30020280 DOI: 10.1039/c8cp03600d] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Real time photodissociation of dihalomethanes has been measured by femtosecond velocity map imaging to disentangle the effect of the halogen-atom on the carbon–iodine cleavage dynamics.
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Affiliation(s)
- Marta L. Murillo-Sánchez
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - Sonia Marggi Poullain
- Departamento de Química
- Módulo 13
- Facultad de Ciencias
- Universidad Autónoma de Madrid
- 28049 Madrid
| | - Juan J. Bajo
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - María E. Corrales
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - Jesús González-Vázquez
- Departamento de Química
- Módulo 13
- Facultad de Ciencias
- Universidad Autónoma de Madrid
- 28049 Madrid
| | - Ignacio R. Solá
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - Luis Bañares
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
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32
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Amini K, Savelyev E, Brauße F, Berrah N, Bomme C, Brouard M, Burt M, Christensen L, Düsterer S, Erk B, Höppner H, Kierspel T, Krecinic F, Lauer A, Lee JWL, Müller M, Müller E, Mullins T, Redlin H, Schirmel N, Thøgersen J, Techert S, Toleikis S, Treusch R, Trippel S, Ulmer A, Vallance C, Wiese J, Johnsson P, Küpper J, Rudenko A, Rouzée A, Stapelfeldt H, Rolles D, Boll R. Photodissociation of aligned CH 3I and C 6H 3F 2I molecules probed with time-resolved Coulomb explosion imaging by site-selective extreme ultraviolet ionization. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2018; 5:014301. [PMID: 29430482 PMCID: PMC5785297 DOI: 10.1063/1.4998648] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/09/2017] [Indexed: 06/08/2023]
Abstract
We explore time-resolved Coulomb explosion induced by intense, extreme ultraviolet (XUV) femtosecond pulses from a free-electron laser as a method to image photo-induced molecular dynamics in two molecules, iodomethane and 2,6-difluoroiodobenzene. At an excitation wavelength of 267 nm, the dominant reaction pathway in both molecules is neutral dissociation via cleavage of the carbon-iodine bond. This allows investigating the influence of the molecular environment on the absorption of an intense, femtosecond XUV pulse and the subsequent Coulomb explosion process. We find that the XUV probe pulse induces local inner-shell ionization of atomic iodine in dissociating iodomethane, in contrast to non-selective ionization of all photofragments in difluoroiodobenzene. The results reveal evidence of electron transfer from methyl and phenyl moieties to a multiply charged iodine ion. In addition, indications for ultrafast charge rearrangement on the phenyl radical are found, suggesting that time-resolved Coulomb explosion imaging is sensitive to the localization of charge in extended molecules.
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Affiliation(s)
- Kasra Amini
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Evgeny Savelyev
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Felix Brauße
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | - Nora Berrah
- Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Cédric Bomme
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Mark Brouard
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Michael Burt
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | | | - Stefan Düsterer
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Benjamin Erk
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | | | | | - Faruk Krecinic
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | - Alexandra Lauer
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Jason W L Lee
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Maria Müller
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
| | - Erland Müller
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Terence Mullins
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Harald Redlin
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Nora Schirmel
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Jan Thøgersen
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
| | | | - Sven Toleikis
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Rolf Treusch
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | | | - Anatoli Ulmer
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
| | - Claire Vallance
- The Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
| | - Joss Wiese
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Per Johnsson
- Department of Physics, Lund University, 22100 Lund, Sweden
| | | | - Artem Rudenko
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
| | - Arnaud Rouzée
- Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 12489 Berlin, Germany
| | | | | | - Rebecca Boll
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
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33
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Murillo-Sánchez M, Marggi Poullain S, González-Vázquez J, Corrales M, Balerdi G, Bañares L. Femtosecond photodissociation dynamics of chloroiodomethane in the first absorption band. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.02.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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34
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Chicharro DV, Marggi Poullain S, González-Vázquez J, Bañares L. Slice imaging of the UV photodissociation of CH 2BrCl from the maximum of the first absorption band. J Chem Phys 2017; 147:013945. [PMID: 28688417 DOI: 10.1063/1.4984789] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The photodissociation dynamics of bromochloromethane (CH2BrCl) have been investigated at the maximum of the first absorption band, at the excitation wavelengths 203 and 210 nm, using the slice imaging technique in combination with a probe detection of bromine-atom fragments, Br(2P3/2) and Br*(2P1/2), via (2 + 1) resonance enhanced multiphoton ionization. Translational energy distributions and angular distributions reported for both Br(2P3/2) and Br*(2P1/2) fragments show two contributions for the Br(2P3/2) channel and a single contribution for the Br*(2P1/2) channel. High level ab initio calculations have been performed in order to elucidate the dissociation mechanisms taking place. The computed absorption spectrum and potential energy curves indicate the main contribution of the populated 4A″, 5A', and 6A' excited states leading to a C-Br cleavage. Consistently with the results, the single contribution for the Br*(2P1/2) channel has been attributed to direct dissociation through the 6A' state as well as an indirect dissociation of the 5A' state requiring a 5A' → 4A' reverse non-adiabatic crossing. Similarly, a faster contribution for the Br(2P3/2) channel characterized by a similar energy partitioning and anisotropy than those for the Br*(2P1/2) channel is assigned to a direct dissociation through the 5A' state, while the slower component appears to be due to the direct dissociation on the 4A″ state.
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Affiliation(s)
- D V Chicharro
- Departmento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - S Marggi Poullain
- Departmento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - J González-Vázquez
- Departamento de Química and Institute for Advanced Research in Chemistry, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - L Bañares
- Departmento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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35
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Poullain SM, Chicharro DV, Rubio-Lago L, García-Vela A, Bañares L. A velocity-map imaging study of methyl non-resonant multiphoton ionization from the photodissociation of CH 3I in the A-band. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2017; 375:rsta.2016.0205. [PMID: 28320907 PMCID: PMC5360903 DOI: 10.1098/rsta.2016.0205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/17/2016] [Indexed: 06/06/2023]
Abstract
Chemical reaction dynamics and, particularly, photodissociation in the gas phase are generally studied using pump-probe schemes where a first laser pulse induces the process under study and a second one detects the produced fragments. Providing an efficient detection of ro-vibrationally state-selected photofragments, the resonance enhanced multiphoton ionization (REMPI) technique is, without question, the most popular approach used for the probe step, while non-resonant multiphoton ionization (NRMPI) detection of the products is scarce. The main goal of this work is to test the sensitivity of the NRMPI technique to fragment vibrational distributions arising from molecular photodissociation processes. We revisit the well-known process of methyl iodide photodissociation in the A-band at around 280 nm, using the velocity-map imaging technique in conjunction with NRMPI of the methyl fragment. The detection wavelength, carefully selected to avoid any REMPI transition, was scanned between 325 and 335 nm seeking correlations between the different observables-the product vibrational, translational and angular distributions-and the excitation wavelength of the probe laser pulse. The experimental results have been discussed on the base of quantum dynamics calculations of photofragment vibrational populations carried out on available ab initio potential-energy surfaces using a four-dimensional model.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.
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Affiliation(s)
- Sonia Marggi Poullain
- Departamento de Química Física I (Unidad Asociada de I+D+I al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - David V Chicharro
- Departamento de Química Física I (Unidad Asociada de I+D+I al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Luis Rubio-Lago
- Departamento de Química Física I (Unidad Asociada de I+D+I al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | | | - Luis Bañares
- Departamento de Química Física I (Unidad Asociada de I+D+I al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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36
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Wittenbrink N, Eisfeld W. An improved spin-orbit coupling model for use within the effective relativistic coupling by asymptotic representation (ERCAR) method. J Chem Phys 2017; 146:144110. [PMID: 28411618 DOI: 10.1063/1.4979949] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
An improved atomic spin-orbit model is presented, which is designed to be used within the framework of the effective relativistic coupling by asymptotic representation method. This method is used for the generation of highly accurate coupled potential energy surfaces (PESs) to represent the fine structure energies of appropriate systems. The approach is demonstrated using CH3I and its photodissociation as a typical example. The method is based on a specific diabatization of electronic spin-space ("spin-free") states with respect to the asymptote at which a single relativistic atom is separated from a molecular non-relativistic fragment. Thus, the relativistic coupling effects can be treated entirely within the atomic framework. So far, an effective spin-orbit coupling operator which only accounts for intra-state coupling within each atomic spin-space state was used. In the present work, this approach is extended to account for inter-state couplings among different atomic spin-space states as well. It is shown that this extended approach improves the accuracy of the PESs significantly for higher excited states and also enhances the accuracy of low energy states. In particular, it improves the representation of the spin-orbit induced conical intersection among the 3Q0 and 1Q1 states of CH3I, which is of high relevance for the nonadiabatic quantum dynamics of the photodissociation.
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Affiliation(s)
- Nils Wittenbrink
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
| | - Wolfgang Eisfeld
- Theoretische Chemie, Universität Bielefeld, Postfach 100131, D-33501 Bielefeld, Germany
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37
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Marggi Poullain S, Chicharro DV, González-Vázquez J, Rubio-Lago L, Bañares L. A velocity map imaging study of the photodissociation of the methyl iodide cation. Phys Chem Chem Phys 2017; 19:7886-7896. [DOI: 10.1039/c7cp00319f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photodissociation dynamics of the methyl iodide cation has been studied using velocity map imaging and ab initio theory to disentangle the dissociation mechanisms.
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Affiliation(s)
- S. Marggi Poullain
- Departamento de Química Física I
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - D. V. Chicharro
- Departamento de Química Física I
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - J. González-Vázquez
- Departamento de Química and Institute for Advanced Research in Chemical Sciences (IAdChem)
- Facultad de Ciencias
- Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
| | - L. Rubio-Lago
- Departamento de Química Física I
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - L. Bañares
- Departamento de Química Física I
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
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38
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Boll R, Erk B, Coffee R, Trippel S, Kierspel T, Bomme C, Bozek JD, Burkett M, Carron S, Ferguson KR, Foucar L, Küpper J, Marchenko T, Miron C, Patanen M, Osipov T, Schorb S, Simon M, Swiggers M, Techert S, Ueda K, Bostedt C, Rolles D, Rudenko A. Charge transfer in dissociating iodomethane and fluoromethane molecules ionized by intense femtosecond X-ray pulses. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2016; 3:043207. [PMID: 27051675 PMCID: PMC4808069 DOI: 10.1063/1.4944344] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Accepted: 03/04/2016] [Indexed: 05/07/2023]
Abstract
Ultrafast electron transfer in dissociating iodomethane and fluoromethane molecules was studied at the Linac Coherent Light Source free-electron laser using an ultraviolet-pump, X-ray-probe scheme. The results for both molecules are discussed with respect to the nature of their UV excitation and different chemical properties. Signatures of long-distance intramolecular charge transfer are observed for both species, and a quantitative analysis of its distance dependence in iodomethane is carried out for charge states up to I(21+). The reconstructed critical distances for electron transfer are in good agreement with a classical over-the-barrier model and with an earlier experiment employing a near-infrared pump pulse.
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Affiliation(s)
| | - Benjamin Erk
- Deutsches Elektronen-Synchrotron (DESY) , 22607 Hamburg, Germany
| | - Ryan Coffee
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | - Sebastian Trippel
- Center for Free-Electron Laser Science, DESY , 22607 Hamburg, Germany
| | | | - Cédric Bomme
- Deutsches Elektronen-Synchrotron (DESY) , 22607 Hamburg, Germany
| | - John D Bozek
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | - Mitchell Burkett
- J.R. Macdonald Laboratory, Kansas State University , Manhattan, Kansas 66506, USA
| | - Sebastian Carron
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | - Ken R Ferguson
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | - Lutz Foucar
- Max Planck Institute for Medical Research , 69120 Heidelberg, Germany
| | | | - Tatiana Marchenko
- Sorbonne Universités , UPMC Univ Paris 06, CNRS, UMR 7614, Laboratoire de Chimie Physique-Matiere et Rayonnement, F-75005 Paris, France
| | | | | | - Timur Osipov
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | - Sebastian Schorb
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | - Marc Simon
- Sorbonne Universités , UPMC Univ Paris 06, CNRS, UMR 7614, Laboratoire de Chimie Physique-Matiere et Rayonnement, F-75005 Paris, France
| | - Michelle Swiggers
- SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | | | - Kiyoshi Ueda
- IMRAM, Tohoku University , 980-8577 Sendai, Japan
| | | | | | - Artem Rudenko
- J.R. Macdonald Laboratory, Kansas State University , Manhattan, Kansas 66506, USA
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39
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Marggi Poullain S, Chicharro DV, Zanchet A, González MG, Rubio-Lago L, Senent ML, García-Vela A, Bañares L. Imaging the photodissociation dynamics of the methyl radical from the 3s and 3pz Rydberg states. Phys Chem Chem Phys 2016; 18:17054-61. [PMID: 27296907 PMCID: PMC5049683 DOI: 10.1039/c6cp01558a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photodissociation dynamics of the methyl radical from the 3s and 3pz Rydberg states have been studied using the velocity map and slice ion imaging in combination with pump-probe nanosecond laser pulses. The reported translational energy and angular distributions of the H((2)S) photofragment detected by (2+1) REMPI highlight different dissociation mechanisms for the 3s and 3pz Rydberg states. A narrow peak in the translational energy distribution and an anisotropic angular distribution characterize the fast 3s photodissociation, while for the 3pz state Boltzmann-type translational energy and isotropic angular distributions are found. High level ab initio calculations have been performed in order to elucidate the photodissociation mechanisms from the two Rydberg states and to rationalize the experimental results. The calculated potential energy curves highlight a typical predissociation mechanism for the 3s state, characterized by the coupling between the 3s Rydberg state and a valence repulsive state. On the other hand, the photodissociation on the 3pz state is initiated by a predissociation process due to the coupling between the 3pz Rydberg state and a valence repulsive state and constrained, later on, by two conical intersections that allow the system to relax to lower electronic states. Such a mechanism opens up different reaction pathways leading to CH2 photofragments in different electronic states and inducing a transfer of energy between translational and internal modes.
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Affiliation(s)
- Sonia Marggi Poullain
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC), 28040 Madrid, Spain.
| | - David V Chicharro
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC), 28040 Madrid, Spain.
| | - Alexandre Zanchet
- Instituto de Física Fundamental, CSIC, C/Serrano, 123, 28006 Madrid, Spain
| | - Marta G González
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC), 28040 Madrid, Spain.
| | - Luis Rubio-Lago
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC), 28040 Madrid, Spain.
| | - María L Senent
- Departamento de Química y Física Teóricas, Instituto de Estructura de la Materia, CSIC, C/Serrano, 121, 28006 Madrid, Spain
| | | | - Luis Bañares
- Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC), 28040 Madrid, Spain.
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40
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Xu H, Pratt ST. Photodissociation of Methyl Iodide via Selected Vibrational Levels of the B̃ ((2)E3/2)6s Rydberg State. J Phys Chem A 2015; 119:7548-58. [PMID: 25946320 DOI: 10.1021/acs.jpca.5b00860] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have determined the I (2)P3/2 and (2)P1/2 branching fractions following the photodissociation of methyl iodide (CH3I) via a number of vibronic bands associated with the B̃ ((2)E3/2)6s Rydberg state at excitation wavelengths between 201.2 and 192.7 nm. Vacuum ultraviolet light at 118.2 nm was used to ionize both the product iodine atoms and the methyl radical cofragments, and velocity map ion imaging was used to determine the product translational energy distributions and angular distributions. The known relative photoionization cross sections for I (2)P3/2 and (2)P1/2 at 118.2 nm were used to determine the corresponding branching fractions. The results extend our earlier work at 193 nm by Xu et al. (J. Chem. Phys. 2013, 139, 214310), and complement the closely related work of González et al. (J. Chem. Phys. 2011, 135, 021102). We find that for most of the excited vibronic levels of the B̃ state studied, the I (2)P3/2 branching ratio is small, but nonzero, and that this channel is associated with internally excited CH3 radicals. The results are discussed in relation to the recent theoretical results of Alekseyev et al. (J. Chem. Phys. 2011, 134, 044303).
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Affiliation(s)
- Hong Xu
- Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - S T Pratt
- Argonne National Laboratory, Argonne, Illinois 60439, United States
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41
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Marggi Poullain S, González MG, Samartzis PC, Kitsopoulos TN, Rubio-Lago L, Bañares L. New insights into the photodissociation of methyl iodide at 193 nm: stereodynamics and product branching ratios. Phys Chem Chem Phys 2015; 17:29958-68. [DOI: 10.1039/c5cp04850h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Stereodynamics imaging provides new insights into the photodissociation of methyl iodide at 193 nm.
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Affiliation(s)
- Sonia Marggi Poullain
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - Marta G. González
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - Peter C. Samartzis
- Institute of Electronic Structure and Laser (IESL)
- Foundation for Research and Technology-Hellas (FORTH)
- Heraklion
- Greece
| | - Theofanis N. Kitsopoulos
- Institute of Electronic Structure and Laser (IESL)
- Foundation for Research and Technology-Hellas (FORTH)
- Heraklion
- Greece
- Department of Chemistry
| | - Luis Rubio-Lago
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
| | - Luis Bañares
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid
- Spain
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42
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Control of ultrafast molecular photodissociation by laser-field-induced potentials. Nat Chem 2014; 6:785-90. [DOI: 10.1038/nchem.2006] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 06/16/2014] [Indexed: 11/09/2022]
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43
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Photofragment translational spectroscopy at 304 nm from C-H symmetric stretch excited CH3I [v 1 = 1]. Sci China Chem 2014. [DOI: 10.1007/s11426-013-5047-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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44
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Hung KC, Tsai PY, Li HK, Lin KC. Photodissociation of CH3CHO at 248 nm by time-resolved Fourier-transform infrared emission spectroscopy: Verification of roaming and triple fragmentation. J Chem Phys 2014; 140:064313. [DOI: 10.1063/1.4862266] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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45
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Rodríguez JD, González MG, Rubio-Lago L, Bañares L. Direct evidence of hydrogen-atom tunneling dynamics in the excited state hydrogen transfer (ESHT) reaction of phenol–ammonia clusters. Phys Chem Chem Phys 2014; 16:3757-62. [DOI: 10.1039/c3cp54362e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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González MG, Rodríguez JD, Rubio-Lago L, Bañares L. Imaging the stereodynamics of methyl iodide photodissociation in the second absorption band: fragment polarization and the interplay between direct and predissociation. Phys Chem Chem Phys 2014; 16:26330-41. [DOI: 10.1039/c4cp03823a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Stereodynamics imaging disentangles the interplay between direct and predissociation in the onset of the second absorption band of methyl iodide.
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Affiliation(s)
- Marta G. González
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid, Spain
| | - Javier D. Rodríguez
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid, Spain
| | - Luis Rubio-Lago
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid, Spain
| | - Luis Bañares
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid
- 28040 Madrid, Spain
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47
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Rodríguez JD, González MG, Rubio-Lago L, Bañares L. A velocity map imaging study of the photodissociation of the à state of ammonia. Phys Chem Chem Phys 2014; 16:406-13. [DOI: 10.1039/c3cp53523a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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48
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Tu CP, Cheng HI, Chang BC. Spectroscopic study of the I2 formation from the photolysis of iodomethanes (CHI3, CH2I2, CH3I, and CH2ICl) at different wavelengths. J Phys Chem A 2013; 117:13572-7. [PMID: 23952939 DOI: 10.1021/jp407599x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Emission spectra following the photolysis of iodomethanes (CHI3, CH2I2, CH3I, and CH2ICl) at 266 nm were recorded in a slow flow cell. In addition to emission from the electronically excited species including CH (A(2)Δ, B(2)Σ(-), and C(2)Σ(+)), C2 (d(3)Πg), and atomic iodine ((4)P(o)), a series of emission bands was observed in the 12,000-19,000 cm(-1) region. The dominant structure of these emission bands was verified as the I2 B(3)Π(+)(0,u)-X(1)Σ(+)g emission at the 532 nm excitation, and the observed I2 was formed from collisions between iodine atoms generated from the C-I bond dissociation in these iodomethanes. The I2 emission spectra following the photolysis of CH2I2 at different wavelengths were acquired, and the threshold energy for the first C-I bond cleavage was determined to be 208 ± 1 kJ mol(-1). We also obtained the emission spectra of pure I2 at several visible excitation wavelengths for comparison with those from the photolysis of iodomethanes, and a least-squares global fit of the observed I2 emission bands yields more accurate anharmonicity parameters for the vibrational structure in the I2 B-X transition.
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Affiliation(s)
- Cian-Ping Tu
- Department of Chemistry, National Central University , 300 Jungda Road, Jhongli 32001, Taiwan
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49
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Xu H, Pratt ST. A new look at the photodissociation of methyl iodide at 193 nm. J Chem Phys 2013; 139:214310. [DOI: 10.1063/1.4829747] [Citation(s) in RCA: 12] [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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50
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Fu B, Han Y, Bowman JM. Three-state surface hopping calculations of acetaldehyde photodissociation to CH3 + HCO on ab initio potential surfaces. Faraday Discuss 2013; 157:27-39; discussion 113-40. [PMID: 23230762 DOI: 10.1039/c2fd20010d] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We report Trajectory Surface Hopping (TSH) calculations of CH3CHO photodissociation involving three electronic states, S1, T1, and S0, with a focus on the radical products CH3 + HCO, which can be formed from both T0 and S0. We use previously reported potential energy surfaces and spin-orbit couplings for T1 and S0 and report a new potential and spin-orbit coupling for S1 here. Roughly 32 000 trajectories are performed at energies corresponding to seven photolysis wavelengths between 372 and 230 nm. Motivated by recent experiments, we examine the branching ratio of the T1 to S0 pathways as a function of photolysis energy. We also present the relative translational energy and CH3 vibrational energy distributions from these pathways at a photolysis energy of 100 kcal mol(-1), formed from both the T1 and S0 potentials. As with standard quasiclassical trajectory calculations, violation of zero-point energy for products also occurs in TSH calculations. This is shown to be a serious issue for this branching ratio and one of several methods considered to deal with this issue is shown to give satisfactory results.
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Affiliation(s)
- Bina Fu
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
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