1
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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: 1] [Impact Index Per Article: 1.0] [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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2
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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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3
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Schubert K, Guda AA, Mertens K, Schunck JO, Schippers S, Müller A, Bari S, Klumpp S, Martins M. Absorption spectra at the iodine 3d ionisation threshold following the CH xI + (x = 0-3) cation sequence. Phys Chem Chem Phys 2019; 21:25415-25424. [PMID: 31710320 DOI: 10.1039/c9cp04640b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Yields of atomic iodine Iq+ (q≥ 2) fragments resulting from photoexcitation and photoionisation of the target cations CHxI+ (x = 0-3) have been measured in the photon-energy range 610 eV to 670 eV, which comprises the threshold for iodine 3d ionisation. The measured ion-yield spectra show two strong and broad resonance features due to the excitation of the 3d3/2,5/2 electrons into εf states similar to atomic iodine. In the 3d pre-edge range, electrons are excited into molecular orbitals consisting of iodine, carbon, and hydrogen atomic orbitals. These transitions have been identified by comparison with literature data and by simulations using time-dependent density functional theory (TDDFT) with the KMLYP functional. The ion-yield spectrum for CH3I+ resembles the spectrum of IH+ [Klumpp et al., Phys. Rev. A, 2018, 97, 033401] because the highest occupied molecular orbitals (HOMO) of the H and CH3 fragments both contain a single vacancy, only. For the molecular cations with higher number of vacancies in the valence molecular orbitals CHxI+ (x = 0-2), a stronger hybridisation of the molecular orbitals occurs between the organic fragment and the iodine resulting in a change of bonding from a single σ bond in CH3I+ to a triple bond including two π orbitals in CI+. This is reflected in the resonance energies of the observed absorption lines below the iodine 3d excitation threshold.
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Affiliation(s)
- Kaja Schubert
- Department Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany. and Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Alexander A Guda
- The Smart Materials Research Institute, Southern Federal University, Sladkova 178/24, 344090 Rostov-on-Don, Russia
| | - Karolin Mertens
- Department Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.
| | - Jan O Schunck
- Department Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany. and Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Stefan Schippers
- Justus-Liebig-Universität Gießen, I. Physikalisches Institut, Heinrich-Buff-Ring 16, 35392 Gießen, Germany
| | - Alfred Müller
- Justus-Liebig-Universität Gießen, Institut für Atom- und Molekülphysik, Leihgesterner Weg 217, 35392 Gießen, Germany
| | - Sadia Bari
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Stephan Klumpp
- Department Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany. and Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Michael Martins
- Department Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany.
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4
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Murillo-Sánchez ML, Marggi Poullain S, Loriot V, Corrales ME, Bañares L. Femtosecond predissociation dynamics of ethyl iodide in the B-band. Phys Chem Chem Phys 2019; 21:15695-15704. [PMID: 31271396 DOI: 10.1039/c9cp02992c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Femtosecond time-resolved velocity map ion imaging experiments are reported on the second absorption band (B-band) of ethyl iodide at 201.19 and 200.08 nm, corresponding to the 000 and 1810 transitions, i.e., the origin of the band and the first most intense vibronic state assigned to one quantum of excitation in the methyl torsion mode. Electronic predissociation lifetimes and the temporal evolution of the anisotropy have been determined by time-resolved resonance-enhanced multiphoton ionization of iodine and ethyl fragment images. A shorter lifetime measured at the origin of the band in comparison with methyl iodide indicates that predissociation in ethyl iodide is more favorable due to a stronger coupling between the initial Rydberg state and the valence repulsive state correlating with the dissociation fragments. Moreover, vibrational activity in the methyl torsion in the Rydberg state seems to enhance the probability of transfer of population to the valence repulsive state leading to a faster dissociation. The perpendicular character of the transition at early times and the loss of anisotropy as a function of time have been determined from the time-resolved angular distributions of the iodine and ethyl ion images. The initial anisotropy value is consistent with a purely perpendicular transition compatible with the excitation of the [6A'', 7A'] states with a minor parallel component to the C-I bond. The loss of initial anisotropy over time highlights the parent molecular rotation during predissociation and is compatible with a rotational temperature of the parent molecule of 100 K.
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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, Spain
| | - Vincent Loriot
- Université Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumiére Matiére, F-69622, Villeurbanne, France
| | - Maria E Corrales
- 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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5
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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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6
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Multidimensional Analysis of Time-Resolved Charged Particle Imaging Experiments. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8081227] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We present a tutorial to realize a multidimensional fitting procedure capable of extracting all the relevant information contained in a sequence of charged particle images acquired as a function of time in femtosecond pump–probe experiments. The images are reproduced using a 3D fitting method, which provides the velocity (or center-of-mass kinetic energy) and angular distributions contained in the images and their time evolution. A detailed example of the method is shown through the analysis of the time-resolved predissociation dynamics of CH3I on the B-band origin (Gitzinger et al., J. Chem. Phys.2010, 133, 234313). We show that the multidimensional approach is essential for the analysis of complex images that contain several overlapping contributions where reduced dimensionality analyses cannot provide a reliable description of the features present in the image sequence. This methodology can be generalized to many types of multidimensional data analysis.
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7
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Baumann A, Rompotis D, Schepp O, Wieland M, Drescher M. Time-Resolved Dissociation Dynamics of Iodomethane Resulting from Rydberg and Valence Excitation. J Phys Chem A 2018; 122:4779-4784. [DOI: 10.1021/acs.jpca.8b01248] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Arne Baumann
- Institute for Experimental Physics, University Hamburg, Hamburg 22761, Germany
- The Hamburg Centre for Ultrafast Imaging—CUI, Hamburg 22761, Germany
| | | | - Oliver Schepp
- Institute for Experimental Physics, University Hamburg, Hamburg 22761, Germany
| | - Marek Wieland
- Institute for Experimental Physics, University Hamburg, Hamburg 22761, Germany
- The Hamburg Centre for Ultrafast Imaging—CUI, Hamburg 22761, Germany
- Center for Free-Electron Laser Science—CFEL, Hamburg 22607, Germany
| | - Markus Drescher
- Institute for Experimental Physics, University Hamburg, Hamburg 22761, Germany
- The Hamburg Centre for Ultrafast Imaging—CUI, Hamburg 22761, Germany
- Center for Free-Electron Laser Science—CFEL, Hamburg 22607, Germany
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8
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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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9
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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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10
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Corrales ME, de Nalda R, Bañares L. Strong laser field control of fragment spatial distributions from a photodissociation reaction. Nat Commun 2017; 8:1345. [PMID: 29116091 PMCID: PMC5677097 DOI: 10.1038/s41467-017-01139-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 08/22/2017] [Indexed: 11/10/2022] Open
Abstract
The notion that strong laser light can intervene and modify the dynamical processes of matter has been demonstrated and exploited both in gas and condensed phases. The central objective of laser control schemes has been the modification of branching ratios in chemical processes, under the philosophy that conveniently tailored light can steer the dynamics of a chemical mechanism towards desired targets. Less explored is the role that strong laser control can play on chemical stereodynamics, i.e. the angular distribution of the products of a chemical reaction in space. This work demonstrates for the case of methyl iodide that when a molecular bond breaking process takes place in the presence of an intense infrared laser field, its stereodynamics is profoundly affected, and that the intensity of this laser field can be used as an external knob to control it.
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Affiliation(s)
- María E Corrales
- Departamento de Química Física (Unidad Asociada de I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Rebeca de Nalda
- Instituto de Química Física Rocasolano, CSIC, C/ Serrano 119, 28006, Madrid, Spain
| | - Luis Bañares
- Departamento de Química Física (Unidad Asociada de I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040, Madrid, Spain.
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11
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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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12
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Corrales ME, Shternin PS, Rubio-Lago L, de Nalda R, Vasyutinskii OS, Bañares L. Femtosecond Time-Resolved Photofragment Rotational Angular Momentum Alignment in Electronic Predissociation Dynamics. J Phys Chem Lett 2016; 7:4458-4463. [PMID: 27786494 DOI: 10.1021/acs.jpclett.6b01874] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This Letter presents an experimental and theoretical study of femtosecond time-resolved vector correlations in methyl iodide (CH3I) electronic predissociation via the second absorption B-band at 201.2 nm. The time evolution of the phenomenological anisotropy parameters βl was determined from time-resolved photofragment angular distributions obtained by means of the femtosecond laser pump-probe technique coupled with velocity map imaging detection of vibrational ground-state CH3(ν = 0) fragments and spin-orbit excited I*(2P1/2) atoms. Theoretical interpretation of the experimental results was performed on the basis of a fitting procedure using quasiclassical theory, which elucidates vector correlations in photodissociation of symmetric top molecules. The results of the fitting are in very good agreement with the experimental data and demonstrate the important role of molecular excited-state lifetimes, parent molecule and methyl fragment rotations, and methyl fragment angular momentum alignment on the time-dependent electronic predissociation dynamics.
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Affiliation(s)
- M E Corrales
- Departamento de Química Física I (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid , 28040 Madrid, Spain
| | - P S Shternin
- Ioffe Institute , Politechnicheskaya 26, 194021 St. Petersburg, Russia
| | - L Rubio-Lago
- Departamento de Química Física I (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid , 28040 Madrid, Spain
| | - R de Nalda
- Instituto de Química Física Rocasolano, CSIC , C/Serrano 119, 28006 Madrid, Spain
| | - O S Vasyutinskii
- Ioffe Institute , Politechnicheskaya 26, 194021 St. Petersburg, Russia
| | - L Bañares
- Departamento de Química Física I (Unidad Asociada I+D+i al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid , 28040 Madrid, Spain
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13
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Balerdi G, Woodhouse J, Zanchet A, de Nalda R, Senent ML, García-Vela A, Bañares L. Femtosecond predissociation dynamics of the methyl radical from the 3pz Rydberg state. Phys Chem Chem Phys 2016; 18:110-8. [DOI: 10.1039/c5cp05710h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vibrationally state selected predissociation lifetimes for the methyl radical in the 3pz Rydberg state have been measured by femtosecond velocity map imaging and the results explained by ab initio theoretical calculations.
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Affiliation(s)
- Garikoitz Balerdi
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC)
- 28040 Madrid
- Spain
| | - Joanne Woodhouse
- Departamento de Química Física
- 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
- Madrid 28006
- Spain
| | | | - Luis Bañares
- Departamento de Química Física
- Facultad de Ciencias Químicas
- Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC)
- 28040 Madrid
- Spain
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14
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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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15
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Solá IR, González-Vázquez J, de Nalda R, Bañares L. Strong field laser control of photochemistry. Phys Chem Chem Phys 2015; 17:13183-200. [PMID: 25835746 DOI: 10.1039/c5cp00627a] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Strong ultrashort laser pulses have opened new avenues for the manipulation of photochemical processes like photoisomerization or photodissociation. The presence of light intense enough to reshape the potential energy surfaces may steer the dynamics of both electrons and nuclei in new directions. A controlled laser pulse, precisely defined in terms of spectrum, time and intensity, is the essential tool in this type of approach to control chemical dynamics at a microscopic level. In this Perspective we examine the current strategies developed to achieve control of chemical processes with strong laser fields, as well as recent experimental advances that demonstrate that properties like the molecular absorption spectrum, the state lifetimes, the quantum yields and the velocity distributions in photodissociation processes can be controlled by the introduction of carefully designed strong laser fields.
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Affiliation(s)
- Ignacio R Solá
- 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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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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17
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Li Q, Zhu R, Lu J, Zhang X, Tang B. Vibrational excitations in chloromethyl radical formed by the photodissociation of chlorobromomethane. J Chem Phys 2014; 140:034303. [PMID: 25669375 DOI: 10.1063/1.4861672] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using velocity map ion imaging, the photodissociation of chlorobromomethane (CH2BrCl) at 233-234 nm has been studied. The total translational energy distributions and the anisotropy parameters have been determined from the ion images of the photofragments Br ((2)P1/2) (denoted as Br(*)) and Br ((2)P3/2) (denoted as Br) for the dominant CH2BrCl + hv → CH2Cl + Br(*) and CH2BrCl + hv → CH2Cl + Br channels. Using an impulsive model invoking angular momentum conservation, the vibrational energy distributions of the chloromethyl radicals have been derived from the total translational energy distributions for the two channels. The study suggests that there are a number of vibrational modes of the chloromethyl radical to be excited in both of the two photodissociation channels. In the Br* channel, the CH2 s-stretch mode v1 has the most probability of excitation. While in the Br channel, the CH2 scissors mode ν2 is attributed to the highest peak of the vibrational energy curve of the chloromethyl radical. The results further imply that, following absorption of one UV photon of 234 nm, other vibrational modes besides v5 (C-Br stretch mode) are also excited in the parent molecule.
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Affiliation(s)
- Qianguang Li
- Department of Physics, Hubei Engineering University, Xiaogan City, Hubei Province 432000, People's Republic of China
| | - Rongshu Zhu
- Environmental Science and Engineering Research Center, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, People's Republic of China
| | - Jinjun Lu
- Department of Physics, Hubei Engineering University, Xiaogan City, Hubei Province 432000, People's Republic of China
| | - Xiu Zhang
- Department of Physics, Hubei Engineering University, Xiaogan City, Hubei Province 432000, People's Republic of China
| | - Bifeng Tang
- Department of Physics, Hubei Engineering University, Xiaogan City, Hubei Province 432000, People's Republic of China
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18
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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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Corrales ME, Loriot V, Balerdi G, González-Vázquez J, de Nalda R, Bañares L, Zewail AH. Structural dynamics effects on the ultrafast chemical bond cleavage of a photodissociation reaction. Phys Chem Chem Phys 2014; 16:8812-8. [DOI: 10.1039/c3cp54677b] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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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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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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Balerdi G, Corrales ME, Gitzinger G, González-Vázquez J, Solá IR, Loriot V, de Nalda R, Bañares L. Dynamic Stark shift of the3R1Rydberg state of CH3I. EPJ WEB OF CONFERENCES 2013. [DOI: 10.1051/epjconf/20134102035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Corrales ME, Balerdi G, Loriot V, de Nalda R, Bañares L. Strong field control of predissociation dynamics. Faraday Discuss 2013; 163:447-60; discussion 513-43. [DOI: 10.1039/c2fd20143g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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24
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Wu X, Dai J, Zhao Y, Zhuo Z, Yang J, Zeng XC. Two-dimensional boron monolayer sheets. ACS NANO 2012; 6:7443-53. [PMID: 22816319 DOI: 10.1021/nn302696v] [Citation(s) in RCA: 362] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Boron, a nearest-neighbor of carbon, is possibly the second element that can possess free-standing flat monolayer structures, evidenced by recent successful synthesis of single-walled and multiwalled boron nanotubes (MWBNTs). From an extensive structural search using the first-principles particle-swarm optimization (PSO) global algorithm, two boron monolayers (α(1)- and β(1)-sheet) are predicted to be the most stable α- and β-types of boron sheets, respectively. Both boron sheets possess greater cohesive energies than the state-of-the-art two-dimensional boron structures (by more than 60 meV/atom based on density functional theory calculation using PBE0 hybrid functional), that is, the α-sheet previously predicted by Tang and Ismail-Beigi and the g(1/8)- and g(2/15)-sheets (both belonging to the β-type) recently reported by Yakobson and co-workers. Moreover, the PBE0 calculation predicts that the α-sheet is a semiconductor, while the α(1)-, β(1)-, g(1/8)-, and g(2/15)-sheets are all metals. When two α(1) monolayers are stacked on top each other, the bilayer α(1)-sheet remains flat with an optimal interlayer distance of ~3.62 Å, which is close to the measured interlayer distance (~3.2 Å) in MWBNTs.
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Affiliation(s)
- Xiaojun Wu
- CAS Key Lab of Materials for Energy Conversion, Department of Materials Science and Engineering and Hefei National Lab for Physical Materials at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
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