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Miao X, Diemer K, Mitrić R. A CASSCF/MRCI trajectory surface hopping simulation of the photochemical dynamics and the gas phase ultrafast electron diffraction patterns of cyclobutanone. J Chem Phys 2024; 160:124309. [PMID: 38526800 DOI: 10.1063/5.0197768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 02/29/2024] [Indexed: 03/27/2024] Open
Abstract
We present the simulation of the photochemical dynamics of cyclobutanone induced by the excitation of the 3 s Rydberg state. For this purpose, we apply the complete active space self-consistent field method together with the spin-orbit multireference configuration interaction singles treatment, combined with the trajectory surface hopping for the inclusion of nonadiabatic effects. The simulations were performed in the spin-adiabatic representation, including nine electronic states derived from three singlet and two triplet spin-diabatic states. Our simulations reproduce the two previously observed primary dissociation channels: the C2 pathway yielding C2H4 + CH2CO and the C3 pathway producing c-C3H6 + CO. In addition, two secondary products, CH2 + CO from the C2 pathway and C3H6 from the C3 pathway, both of them previously reported, are also observed in our simulation. We determine the ratio of the C3:C2 products to be about 2.8. Our findings show that most of the trajectories reach their electronic ground state within 200 fs, with dissociation events finished after 300 fs. We also identify the minimum energy conical intersections that are responsible for the relaxation and provide an analysis of the photochemical reaction mechanism based on multidimensional scaling. Furthermore, we demonstrate a minimal impact of triplet states on the photodissociation mechanism within the observed timescale. In order to provide a direct link to experiments, we simulate the gas phase ultrafast electron diffraction patterns and connect their features to the underlying structural dynamics.
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Affiliation(s)
- Xincheng Miao
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Straße 42, 97074 Würzburg, Germany
| | - Kira Diemer
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Straße 42, 97074 Würzburg, Germany
| | - Roland Mitrić
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Straße 42, 97074 Würzburg, Germany
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Nesbitt DJ, Zolot AM, Roscioli JR, Ryazanov M. Nonequilibrium Scattering/Evaporation Dynamics at the Gas-Liquid Interface: Wetted Wheels, Self-Assembled Monolayers, and Liquid Microjets. Acc Chem Res 2023; 56:700-711. [PMID: 36848588 DOI: 10.1021/acs.accounts.2c00823] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
ConspectusWe often teach or are taught in our freshman courses that there are three phases of matter─gas, liquid and solid─where the ordering reflects increasing complexity and strength of interaction between the molecular constituents. But arguably there is also a fascinating additional "phase" of matter associated with the microscopically thin interface (<10 molecules thick) between the gas and liquid, which is still poorly understood and yet plays a crucial role in fields ranging from chemistry of the marine boundary layer and atmospheric chemistry of aerosols to the passage of O2 and CO2 through alveolar sacs in our lungs. The work in this Account provides insights into three challenging new directions for the field, each embracing a rovibronically quantum-state-resolved perspective. Specifically, we exploit the powerful tools of chemical physics and laser spectroscopy to pose two fundamental questions. (i) At the microscopic level, do molecules in all internal quantum-states (e.g., vibrational, rotational, electronic) colliding with the interface "stick" with unit probability? (ii) Can reactive, scattering, and/or evaporating molecules at the gas-liquid interface avoid collisions with other species and thereby be observed in a truly "nascent" collision-free distribution of internal degrees of freedom? To help address these questions, we present studies in three different areas: (i) reactive scattering dynamics of F atoms with wetted-wheel gas-liquid interfaces, (ii) inelastic scattering of HCl from self-assembled monolayers (SAMs) via resonance-enhanced photoionization (REMPI)/velocity map imaging (VMI) methods, and (iii) quantum-state-resolved evaporation dynamics of NO at the gas-water interface. As a recurring theme, we find that molecular projectiles reactively, inelastically, or evaporatively scatter from the gas-liquid interface into internal quantum-state distributions substantially out of equilibrium with respect to the bulk liquid temperatures (TS). By detailed balance considerations, the data unambiguously indicate that even simple molecules exhibit rovibronic state dependences to how they "stick" to and eventually solvate into the gas-liquid interface. Such results serve to underscore the importance of quantum mechanics and nonequilibrium thermodynamics in energy transfer and chemical reactions at the gas-liquid interface. This nonequilibrium behavior may well make this rapidly emergent field of chemical dynamics at gas-liquid interfaces more complicated but even more interesting targets for further experimental/theoretical exploration.
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Affiliation(s)
- David J Nesbitt
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
- Department of Physics, University of Colorado, Boulder, Colorado 80309, United States
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Alex M Zolot
- Quantinuum, 303 S. Technology Ct., Broomfield, Colorado 80021, United States
| | - Joseph R Roscioli
- Aerodyne Research, Inc., 45 Manning Rd., Billerica, Massachusetts 01821, United States
| | - Mikhail Ryazanov
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, United States
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3
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Bianchini RH, Roman MJ, Costen ML, McKendrick KG. Real-space laser-induced fluorescence imaging applied to gas-liquid interfacial scattering. J Chem Phys 2019. [DOI: 10.1063/1.5110517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Robert H. Bianchini
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Maksymilian J. Roman
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Matthew L. Costen
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Kenneth G. McKendrick
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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Tesa-Serrate MA, Smoll EJ, Minton TK, McKendrick KG. Atomic and Molecular Collisions at Liquid Surfaces. Annu Rev Phys Chem 2016; 67:515-40. [PMID: 27090845 DOI: 10.1146/annurev-physchem-040215-112355] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The gas-liquid interface remains one of the least explored, but nevertheless most practically important, environments in which molecular collisions take place. These molecular-level processes underlie many bulk phenomena of fundamental and applied interest, spanning evaporation, respiration, multiphase catalysis, and atmospheric chemistry. We review here the research that has, during the past decade or so, been unraveling the molecular-level mechanisms of inelastic and reactive collisions at the gas-liquid interface. Armed with the knowledge that such collisions with the outer layers of the interfacial region can be unambiguously distinguished, we show that the scattering of gas-phase projectiles is a promising new tool for the interrogation of liquid surfaces with extreme surface sensitivity. Especially for reactive scattering, this method also offers absolute chemical selectivity for the groups that react to produce a specific observed product.
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Affiliation(s)
- Maria A Tesa-Serrate
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom;
| | - Eric J Smoll
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717;
| | - Timothy K Minton
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717;
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom;
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5
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Tesa-Serrate MA, King KL, Paterson G, Costen ML, McKendrick KG. Site and bond-specific dynamics of reactions at the gas–liquid interface. Phys Chem Chem Phys 2014; 16:173-83. [DOI: 10.1039/c3cp54107j] [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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King KL, Paterson G, Rossi GE, Iljina M, Westacott RE, Costen ML, McKendrick KG. Inelastic scattering of OH radicals from organic liquids: isolating the thermal desorption channel. Phys Chem Chem Phys 2013; 15:12852-63. [DOI: 10.1039/c3cp51708j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Roscioli JR, Bell DJ, Nelson DJ, Nesbitt DJ. State-resolved velocity map imaging of surface-scattered molecular flux. Phys Chem Chem Phys 2012; 14:4070-80. [DOI: 10.1039/c1cp22938a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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8
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Waring C, King KL, Costen ML, McKendrick KG. Dynamics of the Gas−Liquid Interfacial Reaction of O(1D) with a Liquid Hydrocarbon. J Phys Chem A 2011; 115:7210-9. [DOI: 10.1021/jp200292n] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carla Waring
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Kerry L King
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Matthew L Costen
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Kenneth G McKendrick
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
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9
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Waring C, Bagot PAJ, Costen ML, McKendrick KG. Reactive Scattering as a Chemically Specific Analytical Probe of Liquid Surfaces. J Phys Chem Lett 2011; 2:12-18. [PMID: 26295207 DOI: 10.1021/jz1013032] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this Perspective, we highlight some recent progress in the reactive scattering of "chemical probe" species such as atoms or small radicals from liquid surfaces. We emphasize in particular the evolution of this area from purely dynamical studies of the scattering mechanism. The mechanistic understanding that has now been gained is sufficiently mature to allow the same methods to be used as an effective analytical tool. The use of this approach to measure liquid-surface composition and structure is illustrated through the scattering of O((3)P) atoms from a common, imidazolium-based family of ionic liquids.
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Affiliation(s)
- Carla Waring
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Paul A J Bagot
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Matthew L Costen
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Kenneth G McKendrick
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
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10
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Roscioli JR, Nesbitt DJ. Quantum state resolved velocity-map imaging spectroscopy: A new tool for collision dynamics at gas/self-assembled monolayer interfaces. Faraday Discuss 2011; 150:471-9; discussion 505-32. [DOI: 10.1039/c0fd00023j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Waring C, King KL, Bagot PAJ, Costen ML, McKendrick KG. Collision dynamics and reactive uptake of OH radicals at liquid surfaces of atmospheric interest. Phys Chem Chem Phys 2011; 13:8457-69. [DOI: 10.1039/c0cp02734k] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Dynamic QM/MM: A Hybrid Approach to Simulating Gas-Liquid Interactions. MULTISCALE MOLECULAR METHODS IN APPLIED CHEMISTRY 2011; 307:43-67. [DOI: 10.1007/128_2011_130] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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13
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Layfield JP, Troya D. Theoretical study of the dynamics of F+alkanethiol self-assembled monolayer hydrogen-abstraction reactions. J Chem Phys 2010; 132:134307. [DOI: 10.1063/1.3364858] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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14
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Waring C, Bagot PAJ, Slattery JM, Costen ML, McKendrick KG. O(3P) Atoms as a Chemical Probe of Surface Ordering in Ionic Liquids. J Phys Chem A 2010; 114:4896-904. [DOI: 10.1021/jp912045j] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carla Waring
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Paul A. J. Bagot
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - John M. Slattery
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Matthew L. Costen
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Kenneth G. McKendrick
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
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15
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Perkins, Jr. BG, Nesbitt DJ. High resolution Dopplerimetry of correlated angular and quantum state-resolved CO2 scattering dynamics at the gas–liquid interface. Phys Chem Chem Phys 2010; 12:14294-308. [DOI: 10.1039/c0cp00578a] [Citation(s) in RCA: 10] [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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16
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Perkins BG, Nesbitt DJ. Toward Three-Dimensional Quantum State-Resolved Collision Dynamics at the Gas−Liquid Interface: Theoretical Investigation of Incident Angle. J Phys Chem A 2009; 113:4613-25. [DOI: 10.1021/jp811322y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Bradford G. Perkins
- JILA, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
| | - David J. Nesbitt
- JILA, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
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17
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Radak BK, Yockel S, Kim D, Schatz GC. Modeling Reactive Scattering of F(2P) at a Liquid Squalane Interface: A Hybrid QM/MM Molecular Dynamics Study. J Phys Chem A 2009; 113:7218-26. [DOI: 10.1021/jp809546r] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Brian K. Radak
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113
| | - Scott Yockel
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113
| | - Dongwook Kim
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113
| | - George C. Schatz
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113
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18
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Waring C, Bagot PAJ, Räisänen MT, Costen ML, McKendrick KG. Dynamics of the Reaction of O(3P) Atoms with Alkylthiol Self-assembled Monolayers. J Phys Chem A 2009; 113:4320-9. [DOI: 10.1021/jp8109868] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Carla Waring
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K. and School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, U.K
| | - Paul A. J. Bagot
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K. and School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, U.K
| | - Minna T. Räisänen
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K. and School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, U.K
| | - Matthew L. Costen
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K. and School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, U.K
| | - Kenneth G. McKendrick
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K. and School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, U.K
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19
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Nogueira JJ, Vázquez SA, Mazyar OA, Hase WL, Perkins BG, Nesbitt DJ, Martínez-Núñez E. Dynamics of CO2 Scattering off a Perfluorinated Self-Assembled Monolayer. Influence of the Incident Collision Energy, Mass Effects, and Use of Different Surface Models. J Phys Chem A 2009; 113:3850-65. [DOI: 10.1021/jp809756f] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Juan J. Nogueira
- Departamento de Química Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain, Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, and JILA, University of Colorado, and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
| | - Saulo A. Vázquez
- Departamento de Química Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain, Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, and JILA, University of Colorado, and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
| | - Oleg A. Mazyar
- Departamento de Química Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain, Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, and JILA, University of Colorado, and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
| | - William L. Hase
- Departamento de Química Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain, Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, and JILA, University of Colorado, and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
| | - Bradford G. Perkins
- Departamento de Química Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain, Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, and JILA, University of Colorado, and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
| | - David J. Nesbitt
- Departamento de Química Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain, Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, and JILA, University of Colorado, and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
| | - Emilio Martínez-Núñez
- Departamento de Química Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain, Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, and JILA, University of Colorado, and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
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20
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Zolot AM, Dagdigian PJ, Nesbitt DJ. Quantum-state resolved reactive scattering at the gas-liquid interface: F+squalane (C30H62) dynamics via high-resolution infrared absorption of nascent HF(v,J). J Chem Phys 2008; 129:194705. [DOI: 10.1063/1.2973630] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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21
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Perkins BG, Nesbitt DJ. Correlated Angular and Quantum State-Resolved CO2 Scattering Dynamics at the Gas−Liquid Interface. J Phys Chem A 2008; 112:9324-35. [DOI: 10.1021/jp8022887] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bradford G. Perkins
- JILA, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
| | - David J. Nesbitt
- JILA, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440
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22
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Perkins BG, Nesbitt DJ. Quantum state-resolved CO2 collisions at the gas-liquid interface: surface temperature-dependent scattering dynamics. J Phys Chem B 2008; 112:507-19. [PMID: 18052277 DOI: 10.1021/jp077488b] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Energy transfer dynamics at the gas-liquid interface are investigated as a function of surface temperature both by experimental studies of CO2 + perfluorinated polyether (PFPE) and by molecular dynamics simulations of CO2 + fluorinated self-assembled monolayers (F-SAMs). Using a normal incident molecular beam, the experimental studies probe scattered CO2 internal-state and translational distributions with high resolution infrared spectroscopy. At low incident energies [Einc = 1.6(1) kcal/mol], CO2 J-state populations and transverse Doppler velocity distributions are characteristic of the surface temperature (Trot approximately Ttrans approximately TS) over the range from 232 to 323 K. In contrast, the rotational and translational distributions at high incident energies [Einc = 10.6(8) kcal/mol] show evidence for both trapping-desorption (TD) and impulsive scattering (IS) events. Specifically, the populations are surprisingly well-characterized by a sum of Boltzmann distributions where the two components include one (TD) that equilibrates with the surface (TTD approximately TS) and a second (IS) that is much hotter than the surface temperature (TIS > TS). Support for the superthermal, yet Boltzmann, nature of the IS channel is provided by molecular dynamics (MD) simulations of CO2 + F-SAMs [Einc = 10.6 kcal/mol], which reveal two-temperature distributions, sticking probabilities, and angular distributions in near quantitative agreement with the experimental PFPE results. Finally, experiments as a function of surface temperature reveal an increase in both sticking probability and rotational/translational temperature of the IS component. Such a trend is consistent with increased surface roughness at higher surface temperature, which increases the overall probability of trapping, yet preferentially leads to impulsive scattering of more highly internally excited CO2 from the surface.
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Affiliation(s)
- Bradford G Perkins
- JILA, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440, USA
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Perkins BG, Nesbitt DJ. Quantum-State-Resolved CO2 Scattering Dynamics at the Gas−Liquid Interface: Dependence on Incident Angle. J Phys Chem A 2007; 111:7420-30. [PMID: 17580831 DOI: 10.1021/jp0709048] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Energy transfer dynamics at the gas-liquid interface have been probed with a supersonic molecular beam of CO2 and a clean perfluorinated-liquid surface in vacuum. High-resolution infrared spectroscopy measures both the rovibrational state populations and the translational distributions for the scattered CO2 flux. The present study investigates collision dynamics as a function of incident angle (thetainc = 0 degrees, 30 degrees, 45 degrees, and 60 degrees), where column-integrated quantum state populations are detected along the specular-scattering direction (i.e., thetascat approximately thetainc). Internal state rovibrational and Doppler translational distributions in the scattered CO2 yield clear evidence for nonstatistical behavior, providing quantum-state-resolved support for microscopic branching of the gas-liquid collision dynamics into multiple channels. Specifically, the data are remarkably well described by a two-temperature model, which can be associated with both a trapping desorption (TD) component emerging at the surface temperature (Trot approximately TS) and an impulsive scattering (IS) component appearing at hyperthermal energies (Trot > TS). The branching ratio between the TD and IS channels is found to depend strongly on thetainc, with the IS component growing dramatically with increasingly steeper angle of incidence.
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Affiliation(s)
- Bradford G Perkins
- JILA, University of Colorado and National Institute of Standards and Technology, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440, USA
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