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Delgado-Granados LH, Arango CA, López JG. Preparation of vibrational quasi-bound states of the transition state complex BrHBr from the bihalide ion BrHBr . Phys Chem Chem Phys 2022; 24:21250-21260. [PMID: 36040431 DOI: 10.1039/d2cp03120e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Efficient strategies that allow the preparation of molecular systems in particular vibrational states are important in the application of quantum control schemes to chemical reactions. In this paper, we propose the preparation of quasi-bound vibrational states of the collinear transition state complex BrHBr, from vibrational states of the bihalide ion BrHBr-, that favor the bond selective breakage of BrHBr. The results shown complement the investigation that we reported in a previous paper, [A. J. Garzón-Ramírez, J. G. López and C. A. Arango, Int. J. Quantum Chem., 2018, 24, e25784], in which we demonstrated the feasibility of controlling the bond selective decomposition of the collinear BrHBr using linear combinations of reactive resonances. We employed a dipole moment surface, calculated at the QCISD/d-aug-cc-pVTZ level of theory, to simulate the interaction of the BrHBr- ground vibrational state with heuristically optimized sequences of ultrashort infrared linear chirped laser pulses to achieve a target vibrational state, resulting from expanding a chosen linear combination of reactive resonances of BrHBr in terms of vibrational eigenstates of BrHBr-. The results of our simulations show final states that capture the most relevant features of the target state with different levels of description depending on the sequence of laser pulses employed. We also discuss ways of improving the description of the target state and possible limitations of our approach.
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Affiliation(s)
| | - Carlos A Arango
- Departamento de Ciencias Químicas, Universidad Icesi, Cali, Colombia
| | - José G López
- Departamento de Química, Universidad del Valle, A.A. 25360, Cali, Colombia.
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2
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Albertini S, Gruber E, Zappa F, Krasnokutski S, Laimer F, Scheier P. Chemistry and physics of dopants embedded in helium droplets. MASS SPECTROMETRY REVIEWS 2022; 41:529-567. [PMID: 33993543 DOI: 10.1002/mas.21699] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/20/2021] [Accepted: 04/20/2021] [Indexed: 05/18/2023]
Abstract
Helium droplets represent a cold inert matrix, free of walls with outstanding properties to grow complexes and clusters at conditions that are perfect to simulate cold and dense regions of the interstellar medium. At sub-Kelvin temperatures, barrierless reactions triggered by radicals or ions have been observed and studied by optical spectroscopy and mass spectrometry. The present review summarizes developments of experimental techniques and methods and recent results they enabled.
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Affiliation(s)
- Simon Albertini
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Elisabeth Gruber
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Fabio Zappa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Serge Krasnokutski
- Laboratory Astrophysics Group of the MPI for Astronomy, University of Jena, Jena, Germany
| | - Felix Laimer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
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3
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Poterya V, Pysanenko A, Pluhařová E, Votava O, Fárník M. Heterogeneous Reactions of Methane with Cl Radicals on Large Ar N Clusters. J Phys Chem A 2022; 126:249-258. [PMID: 34995071 DOI: 10.1021/acs.jpca.1c08476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heterogeneous chemistry on the surfaces of atmospheric particles has a wide impact on the properties and composition of the Earth's atmosphere. In laboratory studies, clusters can represent proxies to atmospheric aerosols and help to discern the individual steps in reactions on or in aerosols. We investigate the reactivity of Cl and CCl3 radicals with methane on argon clusters using the pickup method. For radical generation, we built a new pyrolysis source partially adapting the design of radical sources that utilize the supersonic expansion into a heated silicon carbide tube. Large ArN, N̅ ≈ 110, clusters were generated in a supersonic expansion, and CH4 molecules were embedded in the clusters via a pickup process followed by the uptake of the radicals produced in the pyrolysis source. The analysis of the mass spectra recorded under different experimental conditions (i.e., with the pyrolysis ON and OFF and with only one or both reactants) allowed us to identify various products of the radical reactions on ArN. We propose a sequence of reactions based on the reaction energetics. It starts with the hydrogen abstraction from CH4 by a Cl radical resulting in HCl and CH3 followed by a halogenation step where CCl4 molecules react with the available CH3 radicals, yielding CH3Cl. By analogy, the CH3Cl enters another hydrogen abstraction by Cl, producing HCl and the CH2Cl radical, which again undergoes a halogenation step with CCl4, generating CH2Cl2. Further reaction of CH2Cl2 with Cl terminates the sequence by the production of HCl and CHCl2.
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Affiliation(s)
- Viktoriya Poterya
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - Andriy Pysanenko
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - Eva Pluhařová
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - Ondřej Votava
- 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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4
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Panzou R, Lewerenz M. Photofragmentation of I2 molecules inside helium clusters: model calculations using a quantum effective potential. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1977862] [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)
- Roland Panzou
- Laboratoire Modélisation et Simulation Multi Echelle, MSME, Univ. Gustave Eiffel, CNRS UMR 8208, Univ. Paris Est Créteil, Marne-la-Vallée, France
| | - Marius Lewerenz
- Laboratoire Modélisation et Simulation Multi Echelle, MSME, Univ. Gustave Eiffel, CNRS UMR 8208, Univ. Paris Est Créteil, Marne-la-Vallée, France
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5
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Moradi CP, Xie C, Kaufmann M, Guo H, Douberly GE. Two-center three-electron bonding in ClNH3 revealed via helium droplet infrared laser Stark spectroscopy: Entrance channel complex along the Cl + NH3 → ClNH2 + H reaction. J Chem Phys 2016; 144:164301. [DOI: 10.1063/1.4947089] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Changjian Xie
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Matin Kaufmann
- Department of Physical Chemistry II, Ruhr-University Bochum, D-44801 Bochum, Germany
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Gary E. Douberly
- Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, USA
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6
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Aoto YA, Köhn A. Revisiting the F + HCl → HF + Cl reaction using a multireference coupled-cluster method. Phys Chem Chem Phys 2016; 18:30241-30253. [DOI: 10.1039/c6cp05782a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A potential energy surface for the title reaction is constructed using a multireference coupled-cluster method, giving rate constant in excellent agreement with experiments.
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Affiliation(s)
- Yuri Alexandre Aoto
- Institut für Theoretische Chemie
- Universität Stuttgart
- D-70569 Stuttgart
- Germany
| | - Andreas Köhn
- Institut für Theoretische Chemie
- Universität Stuttgart
- D-70569 Stuttgart
- Germany
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7
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Product rotational angular momentum polarization of H+FCl (v=0-5; j=0, 3, 6, 9) → HF+Cl and HCl+F at Erel=0.5-20 kcal mol(-1). J Mol Model 2015; 21:309. [PMID: 26564146 DOI: 10.1007/s00894-015-2827-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 09/22/2015] [Indexed: 10/22/2022]
Abstract
The rotational angular momentum polarizations of product molecules of the title reactions on the ground potential energy surface 1 (2)A' of DHTSN [Deskevic et al. J Chem Phys 2006, 124, 224303] have been studied using the quasi-classical trajectory method. Reaction dynamic results of the HF product channel comparing with another channel of HCl with 100,000 trajectories can be accurately resolved. We show the value of the polar p(ϑr) in the range of 0° ≤ ϑr ≤ 180(°), azimuthal p(φr) in the range of 0° ≤ φr ≤ 360(°), and dihedral p(ϑr, φr) in the ranges of 0(°) ≤ ϑr ≤ 180(°) and 0(°) ≤ φr ≤ 360(°); the angular distributions of the product molecules HF and HCl at relative Erel = 0.5, 1, 2, 5, 10, 15, and 20 kcal mol(-1); and four polarization-dependent differential cross sections (PDDCSs) of HF and HCl at Erel = 0.5, 1, 2, 5, 10, and 15 kcal mol(-1). p(φr) distributions at v = 0-5, and j = 0, 3, 6, 9 at every Erel are plotted cylindrically together. The stereo dynamic transformation reaction dependent upon the rovibrational states of the reactant molecule FCl and its relative translational energies around 0.5-5 kcal mol(-1) can be significantly differentiated. Translational and rovibrational enhancements of the title reactions on both early barrier potential energy surfaces have been shown in great detail and clarified. Reaction mechanisms of forward and backward scattering of the product molecules HF and HCl, respectively, have been obtained. Graphical Abstract H + FCl → either HF + Cl (left) or HCl + F (right) is moving along a trajectory on the respective PES.
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8
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Moradi CP, Douberly GE. Infrared Laser Spectroscopy of the L-Shaped Cl–HCl Complex Formed in Superfluid 4He Nanodroplets. J Phys Chem A 2015; 119:12028-35. [DOI: 10.1021/acs.jpca.5b04449] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christopher P. Moradi
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602-2556, United States
| | - Gary E. Douberly
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602-2556, United States
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9
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Vilà A, González M, Mayol R. Photodissociation Dynamics of Homonuclear Diatomic Molecules in Helium Nanodroplets. The Case of Cl2@(4He)N. J Chem Theory Comput 2015; 11:899-906. [DOI: 10.1021/ct5011642] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Arnau Vilà
- Departament
de Química Física i IQTC and ‡Departament d’Estructura
i Constituents de la Matèria, Universitat de Barcelona, c/Martí
i Franquès, 1, 08028 Barcelona, Spain
| | - Miguel González
- Departament
de Química Física i IQTC and ‡Departament d’Estructura
i Constituents de la Matèria, Universitat de Barcelona, c/Martí
i Franquès, 1, 08028 Barcelona, Spain
| | - Ricardo Mayol
- Departament
de Química Física i IQTC and ‡Departament d’Estructura
i Constituents de la Matèria, Universitat de Barcelona, c/Martí
i Franquès, 1, 08028 Barcelona, Spain
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10
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Kautsch A, Koch M, Ernst WE. Photoinduced molecular dissociation and photoinduced recombination mediated by superfluid helium nanodroplets. Phys Chem Chem Phys 2015; 17:12310-6. [DOI: 10.1039/c5cp01009h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoinduced predissociation of Cr2 in helium nanodroplets causes stable, quantum state specific spatial separation followed by geminate recombination upon photoionization.
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Affiliation(s)
- Andreas Kautsch
- Graz University of Technology
- Institute of Experimental Physics
- NAWI Graz
- A-8010 Graz
- Austria
| | - Markus Koch
- Graz University of Technology
- Institute of Experimental Physics
- NAWI Graz
- A-8010 Graz
- Austria
| | - Wolfgang E. Ernst
- Graz University of Technology
- Institute of Experimental Physics
- NAWI Graz
- A-8010 Graz
- Austria
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11
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Duan ZX, Qiu MH, Yao CX. Quasiclassical state-to-state dynamics of the F+HCl reaction on a ground 12A′ potential energy surface. COMPUT THEOR CHEM 2013. [DOI: 10.1016/j.comptc.2013.09.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Takahashi K, Hayes MY, Skodje RT. A study of resonance progressions in the F + HCl → Cl + HF reaction: A lifetime matrix analysis of pre-reactive and post-reactive collision complexes. J Chem Phys 2013; 138:024309. [DOI: 10.1063/1.4774057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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14
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A quasiclassical trajectory analysis of stereodynamics of the H + FCl (v = 0 – 3, j = 0 – 3) → HCl + F reaction. J CHEM SCI 2011. [DOI: 10.1007/s12039-011-0063-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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15
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Wu VWK. Product rotational angular momentum polarization in the H+FCl(v=0-5, j=0, 3, 6, 9)→HF+Cl reaction. Phys Chem Chem Phys 2011; 13:9407-17. [PMID: 21479325 DOI: 10.1039/c0cp02416c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The product alignment and orientation of the title reaction on the ground potential energy surface of 1 (2)A' have been studied using the quasi-classical trajectory method. The calculations were carried out for case (a) at collision energies of 0.5-20 kcal mol(-1) with the initially rovibrational state of the reagent FCl molecule being at the v = 0 and j = 0 level to especially reveal in detail the dependence of the product integral cross section on collision energy. Further calculations at the collision energy of 15 kcal mol(-1) for case (b) at v = 0-5, and j = 0, and (c) at v = 0, and j = 3, 6, 9 initial states were carried out to reveal the effect of initially vibrational and rotational excitations on stereodynamics, respectively. Possessing final relative velocity k' (defined as a vector in the xz-plane), product alignment perpendicular to the reagent relative velocity vector k (defined as z- or parallel to the z-axis), for case (a) is found to be weaker at all collision energies, for case (b) is found to be vibrationally enhanced by the reactant molecule FCl, but for case (c), rather insensitive to initially rotational excitation. The rotational vector of product molecular orientation pointing to either negative or positive direction of the y-axis in the center of mass frame, e.g. origin of the coordinate system, is enhanced by collision energies regarding to 0.5-20 kcal mol(-1), while it becomes weaker at higher vibrational (v = 0-5) or rotational (j = 0, 3, 6, 9) excitation levels. Effects of collision energies and of rotational excitation at these collision energies, with 15 kcal mol(-1) as an example on the calculated PDDCSs are also shown and discussed. Detailed plots P(φ(r)) in the range of 0 ≤φ(r)≤ 360(o), and P(θ(r), φ(r)) in the ranges of 0 ≤θ(r)≤ 180° and 0 ≤φ(r)≤ 360° at collision energies 0.5-20 kcal mol(-1) have been presented. Overall, results of PDDCSs of the product alignment and product orientation at these collision energies in the title reaction are not very strongly distinguishable.
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Affiliation(s)
- Victor Wei-Keh Wu
- Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, 80782 Kaohsiung, Taiwan.
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16
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Isotope effect of the stereodynamics in the reactions F+HCl→HF+Cl and F+DCl→DF+Cl. CHINESE SCIENCE BULLETIN-CHINESE 2010. [DOI: 10.1007/s11434-010-4201-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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17
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Metzelthin A, Havenith M. Observation of the R(0.5)2Π1/2transition of15N18O in helium nanodroplets. Mol Phys 2010. [DOI: 10.1080/00268970701730104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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18
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Toboła R, Chałasiński G, Kłos J, Szczęśniak MM. Ab initio study of the Br([sup 2]P)–HBr van der Waals complex. J Chem Phys 2009; 130:184304. [DOI: 10.1063/1.3123168] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Motegi H, Kakizaki A, Takayanagi T, Taketsugu Y, Taketsugu T, Shiga M. Path-integral molecular dynamics simulations of BeO embedded in helium clusters: Formation of the stable HeBeO complex. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2008.09.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Quéméner G, Balakrishnan N. Cold and ultracold chemical reactions of F+HCl and F+DCl. J Chem Phys 2008; 128:224304. [DOI: 10.1063/1.2928804] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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21
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Takayanagi T, Motegi H, Taketsugu Y, Taketsugu T. Accurate ab initio electronic structure calculations of the stable helium complex: HeBeO. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.01.051] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Kettwich SC, Pinelo LF, Anderson DT. Synthesis and infrared characterization of Br–HBr and Br–DBr entrance channel complexes in solid parahydrogen. Phys Chem Chem Phys 2008; 10:5564-73. [DOI: 10.1039/b806276e] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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23
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Braun A, Drabbels M. Photodissociation of alkyl iodides in helium nanodroplets. I. Kinetic energy transfer. J Chem Phys 2007; 127:114303. [PMID: 17887833 DOI: 10.1063/1.2767261] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The photodissociation of (fluorinated) alkyl iodides in helium nanodroplets at a wavelength of 266 nm has been investigated by means of ion imaging techniques. It is found that a significant fraction of the created fragments escapes from the helium droplets. The speed and kinetic energy distributions of these fragments are found to be notably modified with respect to the corresponding gas phase distributions. The fragments, furthermore, show a speed dependent angular distribution. The loss of kinetic energy as well as the reduction of the anisotropy parameter show a strong mass dependence. These observations point to a nonthermal escape process in which the kinetic energy and momentum transfer from the fragments to the solvent is governed by binary collisions with the individual helium atoms making up the droplet. Monte Carlo simulations based on hard-sphere binary collisions substantiate this interpretation of the data.
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Affiliation(s)
- Andreas Braun
- Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédéral de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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24
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Zolot AM, Nesbitt DJ. Quantum state resolved scattering dynamics of F+HCl→HF(v,J)+Cl. J Chem Phys 2007; 127:114319. [PMID: 17887849 DOI: 10.1063/1.2770464] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
State-to-state reaction dynamics of the reaction F+HCl-->HF(v,J)+Cl have been studied under single-collision conditions using an intense discharge F atom source in crossed supersonic molecular beams at Ecom=4.3(1.3) kcal/mol. Nascent HF product is monitored by shot-noise limited direct infrared laser absorption, providing quantum state distributions as well as additional information on kinetic energy release from high resolution Dopplerimetry. The vibrational distributions are highly inverted, with 34(4)%, 44(2)%, and 8(1)% of the total population in vHF=1, 2, and 3, respectively, consistent with predominant energy release into the newly formed bond. However, there is a small [14(1)%] but significant formation channel into the vHF=0 ground state, which is directly detectable for the first time via direct absorption methods. Of particular dynamical interest, both the HF(v=2,J) and HF(v=1,J) populations exhibit strongly bimodal J distributions. These results differ significantly from previous flow and arrested-relaxation studies and may signal the presence of microscopic branching in the reaction dynamics.
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Affiliation(s)
- A M Zolot
- JILA, National Institute of Standards and Technology and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA
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25
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Merritt JM, Douberly GE, Stiles PL, Miller RE. Infrared Spectroscopy of Prereactive Aluminum−, Gallium−, and Indium−HCN Entrance Channel Complexes Solvated in Helium Nanodroplets. J Phys Chem A 2007; 111:12304-16. [PMID: 17877336 DOI: 10.1021/jp074981e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Prereactive metal atom-HCN entrance channel complexes [M-HCN (M=Al, Ga, In)] have been stabilized in helium nanodroplets. Rotationally resolved infrared spectra are reported for the CH stretching vibration of the linear nitrogen-bound HCN-Ga and HCN-In complexes that show significant perturbation due to spin-orbit coupling of the 2Pi1/2 ground state with the 2Sigma1/2 state which are degenerate at long range. Six unresolved bands are also observed and assigned to the linear hydrogen-bound isomers of Al-HCN, Ga-HCN, and In-HCN corresponding to the fundamental CH stretching vibration and a combination band involving the CH stretch plus intermolecular stretch for each isomer. A nitrogen-bound HCN-Al complex is not observed, which is attributed to reaction, even at 0.37 K. This conclusion is supported by the observation of a weakly bound complex containing two HCN's and one Al atom which, from the analysis of its rotationally resolved zero-field and Stark spectra is assigned to a weakly bound complex of a HCNAl reaction product and a second HCN molecule. Theoretical calculations are presented to elucidate the reaction mechanisms and energetics of these metal atom reactions with HCN.
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Affiliation(s)
- Jeremy M Merritt
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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26
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Fishchuk AV, Merritt JM, van der Avoird A. Ab Initio Treatment of the Chemical Reaction Precursor Complex Br( 2P)−HCN. 1. Adiabatic and Diabatic Potential Surfaces. J Phys Chem A 2007; 111:7262-9. [PMID: 17567108 DOI: 10.1021/jp068495n] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The three adiabatic potential surfaces of the Br(2P)-HCN complex that correlate to the 2P ground state of the Br atom were calculated ab initio. With the aid of a geometry-dependent diabatic mixing angle, also calculated ab initio, these adiabatic potential surfaces were transformed into a set of four diabatic potential surfaces required to define the full 3 x 3 matrix of diabatic potentials. Each of these diabatic potential surfaces was expanded in terms of the appropriate spherical harmonics in the atom-linear molecule Jacobi angle theta. The dependence of the expansion coefficients on the distance R between Br and the HCN center of mass and on the CH bond length was fit to an analytic form. For HCN in its equilibrium geometry, the global minimum with De = 800.4 cm(-1) and Re = 6.908a0 corresponds to a linear Br-NCH geometry, with an electronic ground state of Sigma symmetry. A local minimum with De = 415.1 cm-1, Re = 8.730a0, and a twofold degenerate Pi ground state is found for the linear Br-HCN geometry. The binding energy, De, depends strongly on the CH bond length for the Br-HCN complex and much less strongly for the Br-NCH complex, with a longer CH bond giving stronger binding for both complexes. Spin-orbit coupling was included and diabatic states were constructed that correlate to the ground 2P3/2 and excited 2P1/2 spin-orbit states of the Br atom. For the ground spin-orbit state with electronic angular momentum j = (3/2) the minimum in the potential for projection quantum number omega = +/-(3/2) coincides with the local minimum for linear Br-HCN of the spin-free case. The minimum in the potential for projection quantum number omega = +/-(1/2) occurs for linear Br-NCH but is considerably less deep than the global minimum of the spin-free case. According to the lowest spin-orbit coupling included adiabatic potential the two linear isomers, Br-NCH and Br-HCN, are about equally stable. In the subsequent paper, we use these potentials in calculations of the rovibronic states of the Br-HCN complex.
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Affiliation(s)
- Anna V Fishchuk
- Theoretical Chemistry, IMM, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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Fishchuk AV, Wormer PES, van der Avoird A. Ab initio treatment of the chemical reaction precursor complex Cl(2P)-HF. 1. Three-dimensional diabatic potential energy surfaces. J Phys Chem A 2007; 110:5273-9. [PMID: 16623452 DOI: 10.1021/jp0557619] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The three adiabatic potential surfaces of the Cl(2P)-HF complex that correlate with the 2P ground state of the Cl atom were calculated with the ab initio RCCSD(T) method (partially spin-restricted coupled cluster theory including single and double excitations and perturbative correction for the triples). With the aid of a geometry-dependent diabatic mixing angle, calculated by the complete active space self-consistent field (CASSCF) and multireference configuration-interaction (MRCI) methods, these adiabatic potential surfaces were converted to a set of four distinct diabatic potential surfaces required to define the full 3 x 3 matrix of diabatic potentials. Each of these diabatic potential surfaces was expanded in terms of the appropriate spherical harmonics in the angle theta between the HF bond axis r and the Cl-HF intermolecular axis R. The dependence of the expansion coefficients on the Cl-HF distance R and the HF bond length r(HF) was fit to an analytic form. The strongest binding occurs for the hydrogen-bonded linear Cl-HF geometry, with D(e) = 676.5 cm(-1) and R(e) = 6.217 a0 when r(HF) = r(e) = 1.7328 a0. This binding energy D(e) depends strongly on r(HF), with larger r(HF) causing stronger binding. An important contribution to the binding energy is provided by the interaction between the quadrupole moment of the Cl(2P) atom and the dipole of HF. In agreement with this electrostatic picture, the ground state of linear Cl-HF is a 2-fold degenerate electronic Pi state. For the linear Cl-FH geometry the states are in opposite order, i.e., the Sigma state is lower in energy than the Pi state. The following paper in this issue describes full three-dimensional computations of the bound states of the Cl-HF complex, based on the ab initio diabatic potentials of this paper.
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Affiliation(s)
- Anna V Fishchuk
- Theoretical Chemistry, IMM, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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Loginov E, Drabbels M. Excited State Dynamics of Ag Atoms in Helium Nanodroplets. J Phys Chem A 2007; 111:7504-15. [PMID: 17569515 DOI: 10.1021/jp0716278] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The excited state dynamics of silver atoms embedded in helium nanodroplets have been investigated by a variety of spectroscopic techniques. The experiments reveal that 5p 2P1/2 <-- 5s 2S1/2 excitation of embedded silver atoms results almost exclusively in the ejection of silver atoms populating the 2P1/2 state. In contrast, excitation to the 5p 2P3/2 state leads to the ejection of not only silver atoms in the 2P1/2, 2P3/2, and 2D5/2 excited states but also of AgHe and AgHe2. These AgHe exciplexes are mainly formed in the A2Pi1/2 electronic state. In addition, it is found that a considerable fraction of the 2P3/2 excited silver atoms become solvated within the helium droplets, most probably as AgHe2. The observations can be accounted for by a model in which the metastable 2D5/2 state of silver acts as a doorway state in the relaxation of 2P3/2 excited silver atoms.
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Affiliation(s)
- Evgeniy Loginov
- Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédéral de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Fishchuk AV, Merritt JM, Groenenboom GC, Avoird AVD. Ab Initio Treatment of the Chemical Reaction Precursor Complex Br(2P)−HCN. 2. Bound-State Calculations and Infrared Spectra. J Phys Chem A 2007; 111:7270-81. [PMID: 17567109 DOI: 10.1021/jp0684978] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rovibronic energy levels and properties of the Br(2P)-HCN complex were obtained from three-dimensional calculations, with HCN kept linear and the CN bond frozen. All diabatic states that correlate to the 2P3/2 and 2P1/2 states of the Br atom were included and spin-orbit coupling was taken into account. The 3 x 3 matrix of diabatic potential surfaces was taken from the preceding paper (paper 1). In agreement with experiment, we found two linear isomers, Br-NCH and Br-HCN. The calculated binding energies are very similar: D0 = 352.4 cm(-1) and D0 = 349.1 cm(-1), respectively. We established, also in agreement with experiment, that the ground electronic state of Br-NCH has |Omega| = (1/2) and that Br-HCN has a ground state with |Omega| = (3/2), where the quantum number, Omega, is the projection of the total angular momentum, J, of the complex on the intermolecular axis R. This picture can be understood as being caused by the electrostatic interaction between the quadrupole of the Br(2P) atom and the dipole of HCN, combined with the very strong spin-orbit coupling in Br. We predicted the frequencies of the van der Waals modes of both isomers and found a direct Renner-Teller splitting of the bend mode in Br-HCN and a smaller, indirect, splitting in Br-NCH. The red shift of the CH stretch frequency in the complex, relative to free HCN, was calculated to be 1.98 cm(-1) for Br-NCH and 23.11 cm(-1) for Br-HCN, in good agreement with the values measured in helium nanodroplets. Finally, with the use of the same potential surfaces, we modeled the Cl(2P)-HCN complex and found that the experimentally observed linear Cl-NCH isomer is considerably more stable than the (not observed) Cl-HCN isomer. This was explained mainly as an effect of the substantially smaller spin-orbit coupling in Cl, relative to Br.
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Affiliation(s)
- Anna V Fishchuk
- Theoretical Chemistry, IMM, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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Stiles PL, Miller RE. High-Resolution Infrared Spectroscopy of HCN−Agn (n = 1−4) Complexes Solvated in Superfluid Helium Droplets. J Phys Chem A 2007; 111:7382-90. [PMID: 17518451 DOI: 10.1021/jp0707945] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High-resolution infrared spectroscopy has been used to determine the structures, C-H stretching frequencies, and dipole moments of the HCN-Agn (n = 1-3) complexes formed in superfluid helium droplets. The HCN-Ag4 cluster was tentatively assigned based upon pick-up cell pressure dependencies and harmonic vibrational shift calculations. Ab initio and density functional theory calculations were used in conjunction with the high-resolution spectra to analyze the bonding nature of each cluster. All monoligated species reported here are bound through the nitrogen end of the HCN molecule. The HCN-Agn complexes are structurally similar to the previously reported HCN-Cun clusters, with the exception of the HCN-Ag binary complex. Although the interaction between the HCN and the Agn clusters follows the same trends as the HCN-Cun clusters, the more diffuse nature of the electrons surrounding the silver atoms results in a much weaker interaction.
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Affiliation(s)
- Paul L Stiles
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Küpper J, Merritt JM. Spectroscopy of free radicals and radical containing entrance-channel complexes in superfluid helium nanodroplets. INT REV PHYS CHEM 2007. [DOI: 10.1080/01442350601087664] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Merritt JM, Küpper J, Miller RE. A high-resolution infrared spectroscopic investigation of the halogen atom–HCN entrance channel complexes solvated in superfluid helium droplets. Phys Chem Chem Phys 2007; 9:401-16. [PMID: 17199157 DOI: 10.1039/b611340k] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rotationally resolved infrared spectra are reported for the X-HCN (X = Cl, Br, I) binary complexes solvated in helium nanodroplets. These results are directly compared with those obtained previously for the corresponding X-HF complexes [J. M. Merritt, J. Küpper and R. E. Miller, Phys. Chem. Chem. Phys., 2005, 7, 67]. For bromine and iodine atoms complexed with HCN, two linear structures are observed and assigned to the (2)Sigma(1/2) and (2)Pi(3/2) ground electronic states of the nitrogen and hydrogen bound geometries, respectively. Experiments for HCN + chlorine atoms give rise to only a single band which is attributed to the nitrogen bound isomer. That the hydrogen bound isomer is not stabilized is rationalized in terms of a lowering of the isomerization barrier by spin-orbit coupling. Theoretical calculations with and without spin-orbit coupling have also been performed and are compared with our experimental results. The possibility of stabilizing high-energy structures containing multiple radicals is discussed, motivated by preliminary spectroscopic evidence for the di-radical Br-HCCCN-Br complex. Spectra for the corresponding molecular halogen HCN-X(2) complexes are also presented.
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Affiliation(s)
- Jeremy M Merritt
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Doyle RJ, Hirst DM, Hutson JM. Ab initio potential energy surfaces, bound states, and electronic spectrum of the Ar–SH complex. J Chem Phys 2006; 125:184312. [PMID: 17115757 DOI: 10.1063/1.2371080] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
New ab initio potential energy surfaces for the (2)Pi ground electronic state of the Ar-SH complex are presented, calculated at the RCCSD(T)/aug-cc-pV5Z level. Weakly bound rotation-vibration levels are calculated using coupled-channel methods that properly account for the coupling between the two electronic states. The resulting wave functions are analyzed and a new adiabatic approximation including spin-orbit coupling is proposed. The ground-state wave functions are combined with those obtained for the excited (2)Sigma(+) state [D. M. Hirst, R. J. Doyle, and S. R. Mackenzie, Phys. Chem. Chem. Phys. 6, 5463 (2004)] to produce transition dipole moments. Modeling the transition intensities as a combination of these dipole moments and calculated lifetime values [A. B. McCoy, J. Chem. Phys. 109, 170 (1998)] leads to a good representation of the experimental fluorescence excitation spectrum [M.-C. Yang, A. P. Salzberg, B.-C. Chang, C. C. Carter, and T. A. Miller, J. Chem. Phys. 98, 4301 (1993)].
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Affiliation(s)
- Richard J Doyle
- Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
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Rudić S, Merritt JM, Miller RE. Infrared laser spectroscopy of the CH3–HCN radical complex stabilized in helium nanodroplets. J Chem Phys 2006; 124:104305. [PMID: 16542077 DOI: 10.1063/1.2170087] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The CH3-HCN and CD3-HCN radical complexes have been formed in helium nanodroplets by sequential pickup of a CH3 (CD3) radical and a HCN molecule and have been studied by high-resolution infrared laser spectroscopy. The complexes have a hydrogen-bonded structure with C3v symmetry, as inferred from the analysis of their rotationally resolved nu = 1 <-- 0 H-CN vibrational bands. The A rotational constants of the complexes are found to change significantly upon vibrational excitation of the C-H stretch of HCN within the complex, DeltaA = A'-A" = -0.04 cm(-1) (for CH3-HCN), whereas the B rotational constants are found to be 2.9 times smaller than that predicted by theory. The reduction in B can be attributed to the effects of helium solvation, whereas the large DeltaA is found to be a sensitive probe of the vibrational averaging dynamics of such weakly bound systems. The complex has a permanent electric dipole moment of 3.1 +/- 0.2 D, as measured by Stark spectroscopy. A vibration-vibration resonance is observed to couple the excited C-H stretching vibration of HCN within the complex to the lower-frequency C-H stretches of the methyl radical. Deuteration of the methyl radical was used to detune these levels from resonance, increasing the lifetime of the complex by a factor of 2. Ab initio calculations for the energies and molecular parameters of the stationary points on the CN+CH4 --> HCN+CH3 potential-energy surface are also presented.
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Affiliation(s)
- S Rudić
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Merritt JM, Rudić S, Miller RE. Infrared laser spectroscopy of CH3⋯HF in helium nanodroplets: The exit-channel complex of the F+CH4 reaction. J Chem Phys 2006; 124:084301. [PMID: 16512710 DOI: 10.1063/1.2168450] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
High-resolution infrared laser spectroscopy is used to study the CH3...HF and CD3...HF radical complexes, corresponding to the exit-channel complex in the F + CH4 --> HF + CH3 reaction. The complexes are formed in helium nanodroplets by sequential pickup of a methyl radical and a HF molecule. The rotationally resolved spectra presented here correspond to the fundamental v = 1 <-- 0 H-F vibrational band, the analysis of which reveals a complex with C(3v) symmetry. The vibrational band origin for the CH3...HF complex (3797.00 cm(-1)) is significantly redshifted from that of the HF monomer (3959.19 cm(-1)), consistent with the hydrogen-bonded structure predicted by theory [E. Ya. Misochko et al., J. Am. Chem. Soc. 117, 11997 (1995)] and suggested by previous matrix isolation experiments [M. E. Jacox, Chem. Phys. 42, 133 (1979)]. The permanent electric dipole moment of this complex is experimentally determined by Stark spectroscopy to be 2.4+/-0.3 D. The wide amplitude zero-point bending motion of this complex is revealed by the vibrational dependence of the A rotational constant. A sixfold reduction in the line broadening associated with the H-F vibrational mode is observed in going from CH3...HF to CD3...HF. The results suggest that fast relaxation in the former case results from near-resonant intermolecular vibration-vibration (V-V) energy transfer. Ab initio calculations are also reported (at the MP2 level) for the various stationary points on the F + CH4 surface, including geometry optimizations and vibrational frequency calculations for CH3...HF.
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Affiliation(s)
- J M Merritt
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Fishchuk AV, Groenenboom GC, van der Avoird A. Ab Initio Treatment of the Chemical Reaction Precursor Complex Cl(2P)−HF. 2. Bound States and Infrared Spectrum. J Phys Chem A 2006; 110:5280-8. [PMID: 16623453 DOI: 10.1021/jp0557621] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bound energy levels and properties of the Cl(2P)-HF complex were obtained from full three-dimensional (3D) calculations, with the use of the ab initio computed diabatic potential surfaces from the preceding paper and the inclusion of spin-orbit coupling. For a better understanding of the dynamics of this complex we also computed a 2D model in which the HF bond length r was frozen at the vibrationally averaged values r0 and r1 and a 2 + 1D model in which the 3D potentials were averaged over the v(HF) = 0 and v(HF) = 1 vibrational wave functions of free HF. Also 1D calculations were made in which both r and the Cl-HF distance R were frozen. The complex is found to have the linear hydrogen bonded Cl-HF structure, with ground-state quantum numbers J = 3/2 for the overall angular momentum and /omega/ = 3/2 for its projection on the intermolecular axis R. The binding energy is D0 = 432.25 cm(-1) for v(HF) = 0 and D0 = 497.21 cm(-1) for v(HF) = 1. Bending modes with /omega/ = 1/2 and /omega/ = 5/2 are split by the Renner-Teller effect, since the electronic ground state is a degenerate 2pi state. A series of intermolecular (R) stretch modes was identified. Rotational constants and e-f parity splittings were extracted from the levels computed for J = 1/2 to 7/2. The computed red shift of the HF stretch frequency of 64.96 cm(-1) and the 35Cl-37Cl isotope shift of 0.033 cm(-1) are in good agreement with the values of 68.77 and 0.035 cm(-1) obtained from the recent experiment of Merritt et al. (Phys. Chem. Chem. Phys. 2005, 7, 67), after correction for the effect of the He nanodroplet matrix in which they were measured.
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Affiliation(s)
- Anna V Fishchuk
- Institute of Theoretical Chemistry, IMM, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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Roger E. Miller: Publications. INT REV PHYS CHEM 2006. [DOI: 10.1080/01442350600709243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Pirani F, Maciel GS, Cappelletti D, Aquilanti V. Experimental benchmarks and phenomenology of interatomic forces: open-shell and electronic anisotropy effects. INT REV PHYS CHEM 2006. [DOI: 10.1080/01442350600674033] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Choi MY, Douberly GE, Falconer TM, Lewis WK, Lindsay CM, Merritt JM, Stiles PL, Miller RE. Infrared spectroscopy of helium nanodroplets: novel methods for physics and chemistry. INT REV PHYS CHEM 2006. [DOI: 10.1080/01442350600625092] [Citation(s) in RCA: 327] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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von Haeften K, Metzelthin A, Rudolph S, Staemmler V, Havenith M. High-resolution spectroscopy of NO in helium droplets: a prototype for open shell molecular interactions in a quantum solvent. PHYSICAL REVIEW LETTERS 2005; 95:215301. [PMID: 16384151 DOI: 10.1103/physrevlett.95.215301] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Indexed: 05/05/2023]
Abstract
We have measured the high-resolution infrared spectrum of the radical NO in the (2)Pi(1/2) state in superfluid helium nanodroplets. The features are attributed to the -doubling splitting and the hyperfine structure. The hyperfine interaction is found to be unaffected by the He solvation. For the Lambda-doubling splitting, we find a considerable increase by 55% compared to the gas phase. This is explained by a confinement of the electronically excited NO states by the surrounding He. The rotational level spacing is decreased to 76% of the gas phase value. The IR transition to the J=1.5 state is found to be homogeneously broadened. We attribute both observations to the coupling between the molecular rotation and phonon/roton excitations in superfluid (4)He droplets.
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Affiliation(s)
- K von Haeften
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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Murray C, Pearce JK, Rudić S, Retail B, Orr-Ewing AJ. Stereodynamics of Chlorine Atom Reactions with Organic Molecules. J Phys Chem A 2005; 109:11093-102. [PMID: 16331891 DOI: 10.1021/jp054627l] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of recent experimental and computational studies has explored how the dynamics of hydrogen abstraction from organic molecules are affected by the presence of functional groups in the molecule and by basic structural motifs such as strained ring systems. Comparisons drawn between reactions of Cl atoms with alkanes such as ethane, Cl + CH3CH3--> HCl + CH3CH2, which serve as benchmark systems, and with functionalized molecules such as alcohols, amines, and alkyl halides, Cl + CH3X --> HCl + CH2X (X = OH, NH2, halogen, etc.) expose a wealth of mechanistic detail. Although the scattering dynamics, as revealed from measured angular distributions of the velocities of the HCl with quantum-state resolution, show many similarities, much-enhanced rotational excitation of the HCl products is observed from reactions of the functionalized molecules. The degree of rotational excitation of the HCl correlates with the dipole moment of the CH2X radical and is thus attributed, at least in part, to post-transition-state dipole-dipole interactions between the separating, polar reaction products. This interpretation is supported by direct dynamics trajectories computed on-the-fly, and the HCl rotation is thus argued to serve as an in situ probe of the angular anisotropy of the reaction potential energy surface in the post-transition-state region. Comparisons between the dynamics of reactions of dimethyl ether and the three- and four-membered-ring compounds oxirane (c-C2H4O) and oxetane (c-C3H6O) raise questions about the role of reorientation of the reaction products on a time scale commensurate with their separation. The shapes and structures of polyatomic molecules are thus demonstrated to have important consequences for the stereodynamics of these direct abstraction reactions.
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Affiliation(s)
- Craig Murray
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK
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Loginov E, Rossi D, Drabbels M. Photoelectron spectroscopy of doped helium nanodroplets. PHYSICAL REVIEW LETTERS 2005; 95:163401. [PMID: 16241798 DOI: 10.1103/physrevlett.95.163401] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2005] [Indexed: 05/05/2023]
Abstract
The photoionization dynamics of aniline doped helium droplets has been investigated by photoelectron spectroscopy. The photoelectron spectra resemble closely that of gas phase aniline, except for a droplet-size-dependent shift. This shift is caused by lowering of the ionization threshold upon solvation and can be readily estimated. The individual peaks in the photoelectron spectrum are broadened towards lower kinetic energy which is attributed to the relaxation of the photoelectrons as they pass through the helium droplet.
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Affiliation(s)
- Evgeniy Loginov
- Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne (EPFL)
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Abstract
The OH-He complex has been observed using laser excitation of the A 2sigma+-X 2pi transition. The bands of the complex were close to the monomer rotational lines that terminate on the n = 0, 1, and 2 levels of OH(A). The unresolved band associated with He.OH (A,n=0) was redshifted from the OH parent line by 1.6 cm(-1), providing a direct measurement of D0'-D0". The complex features associated with n = 1 and 2 were identified as scattering resonances. They have been assigned by comparison with resonance structures derived from close-coupling calculations. The ab initio potential energy surface of H.-S. Lee, A.B. McCoy, R.R. Toczylowski, and S.M. Cybulski, [J. Chem. Phys. 113, 5736 (2000)] was used in these calculations. The level of agreement between the observed and predicted resonances indicated that the ab initio surface is reasonably accurate.
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Affiliation(s)
- Jiande Han
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA
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