1
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Conformer Selection by Electrostatic Hexapoles: A Theoretical Study on 1-Chloroethanol and 2-Chloroethanol. Symmetry (Basel) 2022. [DOI: 10.3390/sym14020317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022] Open
Abstract
The electrostatic hexapole is a versatile device that has been used for many years in gas-phase experiments. Its inhomogeneous electric field has been employed for many purposes such as the selection of rotational states, the selection of clusters, the focusing of molecular beams, and molecular alignment as a precursor for molecular orientation. In the last few years, the hexapolar electric field has been demonstrated to be able to control the conformer composition of molecular beams. The key point is that conformers, where the component of the permanent electric dipole moment with respect to the largest of the principal axes of inertia is close to zero, require more intense hexapolar electric fields to be focused with respect to the other conformers. Here, we simulated the focusing curves of the conformers of 1-chloroethanol and 2-chloroethanol under hypothetical beam conditions, identical for all conformers, in a hypothetical and realistic experimental setup with three different hexapole lengths: 0.5, 1, and 2 m. The objective was to characterize this selection process to set up collision experiments on conformer-selected beams that provide information on the van der Waals clusters formed in collision processes.
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2
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Ploenes L, Straňák P, Gao H, Küpper J, Willitsch S. A novel crossed-molecular-beam experiment for investigating reactions of state- and conformationally selected strong-field-seeking molecules. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1965234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- L. Ploenes
- Department of Chemistry, University of Basel, Basel, Switzerland
| | - P. Straňák
- Department of Chemistry, University of Basel, Basel, Switzerland
| | - H. Gao
- Department of Chemistry, University of Basel, Basel, Switzerland
| | - J. Küpper
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
- Center for Ultrafast Imaging, Universität Hamburg, Hamburg, Germany
- Department of Physics, Universität Hamburg, Hamburg, Germany
- Department of Chemistry, Universität Hamburg, Hamburg, Germany
| | - S. Willitsch
- Department of Chemistry, University of Basel, Basel, Switzerland
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3
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Nakamura M, Palazzetti F, Tsai PY, Yang SJ, Lin KC, Kasai T, Che DC, Lombardi A, Aquilanti V. Vectorial imaging of the photodissociation of 2-bromobutane oriented via hexapolar state selection. Phys Chem Chem Phys 2019; 21:14164-14172. [PMID: 30350830 DOI: 10.1039/c8cp04270e] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular orientation techniques are becoming available in the study of elementary chemical processes, in order to highlight those structural and dynamical properties that would be concealed by random rotational motions. Recently successful orientation was achieved for asymmetric-top and chiral molecules of much larger complexity than hitherto. In this work, we report and discuss the correlation between the vectors' photofragment recoil velocity v, transition dipole moment μ, and permanent dipole moment d in a dissociation experiment on hexapole oriented 2-bromobutane, photoinitiated by a linearly polarized laser. The sliced ion images of the Br*(2P1/2) and Br(2P3/2) photofragments were acquired at 234.0 and 254.1 nm, respectively, by a (2 + 1) resonance-enhanced multiphoton ionization technique. A detailed analysis of the sliced ion images obtained at a tilting angle 45° of laser polarization provides information on the correlation of the three vectors, which are confined by two polar angles α and χ and one azimuthal angle φμd in the recoil frame. The sliced ion images of Br fragments eliminated individually from the enantiomers at 254.1 nm yield an asymmetric factor close to zero; for this reason the photofragment angular distributions do not show significant differences. The elimination of the Br* fragment at 234.0 nm is mainly correlated with a parallel transition, giving rise to a large anisotropy parameter of 1.85, and thus can be considered as a single state excitation. The resulting recoil frame angles are optimized to 163° ± 8° and 164° ± 1° for α and χ, respectively, whereas φμd is approaching 0° for the best fit. Since for the present molecule, the three vectors have an only slight spatial arrangement, the photofragment angular distributions of the two enantiomers do not show appreciable differences. Theoretical and computational simulations provide us the basis to state that oriented enantiomers can be discriminated on-the-fly in photodissociation processes even initiated by non-circularly polarized light, provided that the three vectors encountered above have specific three-dimensional arrangements. The fact that Br fragment elimination involves a multi-potential dissociation carries uncertainties in theoretical estimates of the vector direction. Therefore, this work represents a preliminary but significant step on the road to chiral discrimination on-the-fly, which is shown to be best propitiated in molecules where vectors are far from having degenerate mutual angular directions.
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Affiliation(s)
- Masaaki Nakamura
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
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4
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Coutinho ND, Sanches-Neto FO, Carvalho-Silva VH, de Oliveira HCB, Ribeiro LA, Aquilanti V. Kinetics of the OH+HCl→H 2 O+Cl reaction: Rate determining roles of stereodynamics and roaming and of quantum tunneling. J Comput Chem 2018; 39:2508-2516. [PMID: 30365178 DOI: 10.1002/jcc.25597] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/15/2018] [Accepted: 08/20/2018] [Indexed: 02/03/2023]
Abstract
The OH + HCl → H2 O + Cl reaction is one of the most studied four-body systems, extensively investigated by both experimental and theoretical approaches. Here, as a continuation of our previous work on the OH + HBr and OH + HI reactions, which manifest an anti-Arrhenius behavior that was explained by stereodynamic and roaming effects, we extend the strategy to understand the transition to the sub-Arrhenius behavior occurring for the HCl case. As previously, we perform first-principles on-the-fly Born-Oppenheimer molecular dynamics calculations, thermalized at four temperatures (50, 200, 350, and 500 K), but this time we also apply a high-level transition-state-theory, modified to account for tunneling conditions. We find that the theoretical rate constants calculated with Bell tunneling corrections are in good agreement with extensive experimental data available for this reaction in the ample temperature range: (i) simulations show that the roles of molecular orientation in promoting this reaction and of roaming in finding the favorable path are minor than in the HBr and HI cases, and (ii) dominating is the effect of quantum mechanical penetration through the energy barrier along the reaction path on the potential energy surface. The discussion of these results provides clarification of the origin on different non-Arrhenius mechanisms observed along this series of reactions. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Nayara D Coutinho
- Instituto de Química, Universidade de Brasília, Caixa Postal 4478, 70904-970, Brasília, Brazil
| | - Flavio O Sanches-Neto
- Grupo de Química Teórica e Estrutural de Anápolis, Ciências Exatas e Tecnológicas, Universidade Estadual de Goiás, CP 459, 75001-970, Anápolis, GO, Brazil
| | | | - Heibbe C B de Oliveira
- Instituto de Química, Universidade de Brasília, Caixa Postal 4478, 70904-970, Brasília, Brazil
| | - Luiz A Ribeiro
- Institute of Physics, University of Brasilia, Brasilia, 70910-900, Brazil
| | - Vincenzo Aquilanti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy.,Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Area dela Ricerca di Roma Tor Vergata, Via del Fosso del Cavaliere, 00133, Rome, Italy
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5
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Wang Y, Wang D. Quantum dynamics calculations reveal temperature independence of kinetic isotope effect of the OH + HBr/DBr reaction. J Chem Phys 2018; 149:034302. [DOI: 10.1063/1.5037542] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Yuping Wang
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China
| | - Dunyou Wang
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China
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6
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Kasai T, Che DC, Tsai PY, Nakamura M, Muthiah B, Lin KC. Roaming and chaotic behaviors in collisional and photo-initiated molecular-beam reactions: a role of classical vs. quantum nonadiabatic dynamics. RENDICONTI LINCEI. SCIENZE FISICHE E NATURALI 2018. [DOI: 10.1007/s12210-018-0709-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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7
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Nakamura M, Yang SJ, Lin KC, Kasai T, Che DC, Lombardi A, Palazzetti F, Aquilanti V. Stereodirectional images of molecules oriented by a variable-voltage hexapolar field: Fragmentation channels of 2-bromobutane electronically excited at two photolysis wavelengths. J Chem Phys 2017; 147:013917. [DOI: 10.1063/1.4981025] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Masaaki Nakamura
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Shiun-Jr Yang
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - King-Chuen Lin
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Toshio Kasai
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
- Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Dock-Chil Che
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Andrea Lombardi
- Università di Perugia, Dipartimento di Chimica, Biologia e Biotecnologie, 06123 Perugia, Italy
| | - Federico Palazzetti
- Università di Perugia, Dipartimento di Chimica, Biologia e Biotecnologie, 06123 Perugia, Italy
| | - Vincenzo Aquilanti
- Università di Perugia, Dipartimento di Chimica, Biologia e Biotecnologie, 06123 Perugia, Italy
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, 00016 Rome, Italy
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8
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Wang Y, Li Y, Wang D. Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier. Sci Rep 2017; 7:40314. [PMID: 28071762 PMCID: PMC5223161 DOI: 10.1038/srep40314] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/01/2016] [Indexed: 01/04/2023] Open
Abstract
A time-dependent, quantum reaction dynamics approach in full dimensional, six degrees of freedom was carried out to study the energy requirement on reactivity for the HBr + OH reaction with an early, negative energy barrier. The calculation shows both the HBr and OH vibrational excitations enhance the reactivity. However, even this reaction has a negative energy barrier, the calculation shows not all forms of energy are equally effective in promoting the reactivity. On the basis of equal amount of total energy, the vibrational energies of both the HBr and OH are more effective in enhancing the reactivity than the translational energy, whereas the rotational excitations of both the HBr and OH hinder the reactivity. The rate constants were also calculated for the temperature range between 5 to 500 K. The quantal rate constants have a better slope agreement with the experimental data than quasi-classical trajectory results.
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Affiliation(s)
- Yuping Wang
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China
| | - Yida Li
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China
| | - Dunyou Wang
- College of Physics and Electronics, Shandong Normal University, Jinan 250014, Shandong, China
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9
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Tsai PY. On the state selection of linear triatomic molecules by electrostatic hexapole fields. J Chem Phys 2016; 145:104311. [PMID: 27634264 DOI: 10.1063/1.4962359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Electrostatic hexapole state-selector is a versatile tool in experimental stereodynamics. The requirement of appropriate models to correctly predict the behavior of molecules in the hexapole motivated us to realize a treatment that predicts the Stark effect of linear triatomic molecules with rotational doublet states. Various perturbative approximations are conventionally adopted to obtain analytic Stark energy derivatives of a truncated Hamiltonian matrix, without utilizing numerical diagonalization of the full Hamiltonian matrix. By including both the low and high field effects, which were alternatively ignored in the analytical formulae of such approximate approaches, herein we demonstrate that the performance of hexapole state selector to linear triatomic molecules can be appropriately predicted via Van Vleck transformation. This method can provide analytic Stark energy derivatives that are acceptably in consistent with the ones obtained via numerical diagonalization of the full Hamiltonian matrix. Particularly, this work is suitable for v2 = 1 level of linear triatomic molecules, due to the following reasons: (1) the Stark energy derivative and the molecular orientation as a function of the electric field are expressed in analytical formulae, hence it is suitable for implementation without involving numerical diagonalization of the full Hamiltonian matrix; (2) a better prediction of the focusing curves with respect to conventional analytical treatments is provided, allowing a reliable determination of the selected state compositions and molecular orientation.
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Affiliation(s)
- Po-Yu Tsai
- Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan
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10
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Falcinelli S, Rosi M, Cavalli S, Pirani F, Vecchiocattivi F. Stereoselectivity in Autoionization Reactions of Hydrogenated Molecules by Metastable Noble Gas Atoms: The Role of Electronic Couplings. Chemistry 2016; 22:12518-26. [PMID: 27470487 DOI: 10.1002/chem.201601811] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Indexed: 11/09/2022]
Abstract
Focus in the present paper is on the analysis of total and partial ionization cross sections, measured in absolute value as a function of the collision energy, representative of the probability of ionic product formation in selected electronic states in Ne*-H2 O, H2 S, and NH3 collisions. In order to characterize the imaginary part of the optical potential, related to electronic couplings, we generalize a methodology to obtain direct information on the opacity function of these reactions. Such a methodology has been recently exploited to test the real part of the optical potential (S. Falcinelli et al., Chem. Eur. J., 2016, 22, 764-771). Depending on the balance of noncovalent contributions, the real part controls the approach of neutral reactants, the removal of ionic products, and the structure of the transition state. Strength, range, and stereoselectivity of electronic couplings, triggering these and many other reactions, are directly obtained from the present investigation.
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Affiliation(s)
- Stefano Falcinelli
- Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125, Perugia, Italy.
| | - Marzio Rosi
- Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125, Perugia, Italy
| | - Simonetta Cavalli
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy
| | - Fernando Pirani
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di Sotto 8, 06123, Perugia, Italy
| | - Franco Vecchiocattivi
- Department of Civil and Environmental Engineering, University of Perugia, Via G. Duranti 93, 06125, Perugia, Italy
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11
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Nakamura M, Yang SJ, Tsai PY, Kasai T, Lin KC, Che DC, Lombardi A, Palazzetti F, Aquilanti V. Hexapole-Oriented Asymmetric-Top Molecules and Their Stereodirectional Photodissociation Dynamics. J Phys Chem A 2016; 120:5389-98. [PMID: 27139246 DOI: 10.1021/acs.jpca.6b02410] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular orientation is a fundamental requisite in the study of stereodirected dynamics of collisional and photoinitiated processes. In this past decade, variable hexapolar electric filters have been developed and employed for the rotational-state selection and the alignment of molecules of increasing complexity, for which the main difficulties are their mass, their low symmetry, and the very dense rotational manifold. In this work, for the first time, a complex molecule such as 2-bromobutane, an asymmetric top containing a heavy atom (the bromine), was successfully oriented by a weak homogeneous field placed downstream from the hexapolar filter. Efficiency of the orientation was characterized experimentally, by combining time-of-flight measurements and a slice-ion-imaging detection technique. The application is described to the photodissociation dynamics of the oriented 2-bromobutane, which was carried out at a laser wavelength of 234 nm, corresponding to the breaking of the C-Br bond. The Br photofragment is produced in both the ground Br ((2)P3/2) and the excited Br ((2)P1/2) electronic states, and both channels are studied by the slice imaging technique, revealing new features in the velocity and angular distributions with respect to previous investigations on nonoriented molecules.
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Affiliation(s)
- Masaaki Nakamura
- Department of Chemistry, National Taiwan University , Taipei, Taiwan
| | - Shiun-Jr Yang
- Department of Chemistry, National Taiwan University , Taipei, Taiwan
| | - Po-Yu Tsai
- Department of Chemistry, National Taiwan University , Taipei, Taiwan.,Department of Chemistry, National Chung-Hsing University , Taichung, Taiwan
| | - Toshio Kasai
- Department of Chemistry, National Taiwan University , Taipei, Taiwan
| | - King-Chuen Lin
- Department of Chemistry, National Taiwan University , Taipei, Taiwan.,Institute of Atomic and Molecular Sciences, Academia Sinica , Taipei, Taiwan
| | - Dock-Chil Che
- Graduate School of Science, Department of Chemistry, Osaka University , Osaka, Japan
| | - Andrea Lombardi
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia , Perugia, Italy
| | - Federico Palazzetti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia , Perugia, Italy.,Scuola Normale Superiore , Pisa, Italy
| | - Vincenzo Aquilanti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia , Perugia, Italy.,Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia , 00016 Roma, Italy.,Insituto de Fìsica, Universidade Federal da Bahia , Salvador, Brazil
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12
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Coutinho ND, Aquilanti V, Silva VHC, Camargo AJ, Mundim KC, de Oliveira HCB. Stereodirectional Origin of anti-Arrhenius Kinetics for a Tetraatomic Hydrogen Exchange Reaction: Born-Oppenheimer Molecular Dynamics for OH + HBr. J Phys Chem A 2016; 120:5408-17. [PMID: 27205872 DOI: 10.1021/acs.jpca.6b03958] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Among four-atom processes, the reaction OH + HBr → H2O + Br is one of the most studied experimentally: its kinetics has manifested an unusual anti-Arrhenius behavior, namely, a marked decrease of the rate constant as the temperature increases, which has intrigued theoreticians for a long time. Recently, salient features of the potential energy surface have been characterized and most kinetic aspects can be considered as satisfactorily reproduced by classical trajectory simulations. Motivation of the work reported in this paper is the investigation of the stereodirectional dynamics of this reaction as the prominent reason for the peculiar kinetics: we started in a previous Letter ( J. Phys. Chem. Lett. 2015 , 6 , 1553 - 1558 ) a first-principles Born-Oppenheimer "canonical" molecular dynamics approach. Trajectories are step-by-step generated on a potential energy surface quantum mechanically calculated on-the-fly and are thermostatically equilibrated to correspond to a specific temperature. Here, refinements of the method permitted a major increase of the number of trajectories and the consideration of four temperatures -50, +200, +350, and +500 K, for which the sampling of initial conditions allowed us to characterize the stereodynamical effect. The role is documented of the adjustment of the reactants' mutual orientation to encounter the entrance into the "cone of acceptance" for reactivity. The aperture angle of this cone is dictated by a range of directions of approach compatible with the formation of the specific HOH angle of the product water molecule; and consistently the adjustment is progressively less effective the higher the kinetic energy. Qualitatively, this emerging picture corroborates experiments on this reaction, involving collisions of aligned and oriented molecular beams, and covering a range of energies higher than the thermal ones. The extraction of thermal rate constants from this molecular dynamics approach is discussed and the systematic sampling of the canonical ensemble is indicated as needed for quantitative comparison with the kinetic experiments.
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Affiliation(s)
- Nayara D Coutinho
- Instituto de Química, Universidade de Brasília , 4478, 70904-970 Brasília, Brazil
| | - Vincenzo Aquilanti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia , Via Elce di Sotto 8, 06123, Perugia, Italy.,Instituto de Física, Universidade Federal da Bahia , 40210 Salvador, Brazil.,Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche , 00016 Rome, Italy
| | - Valter H C Silva
- Grupo de Química Teórica e Estrutural de Anápolis, Ciências Exatas e Tecnológicas, Universidade Estadual de Goiás , 0459, 75001-970 Anápolis, GO Brazil
| | - Ademir J Camargo
- Grupo de Química Teórica e Estrutural de Anápolis, Ciências Exatas e Tecnológicas, Universidade Estadual de Goiás , 0459, 75001-970 Anápolis, GO Brazil
| | - Kleber C Mundim
- Instituto de Química, Universidade de Brasília , 4478, 70904-970 Brasília, Brazil
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13
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Coutinho ND, Silva VHC, de Oliveira HCB, Camargo AJ, Mundim KC, Aquilanti V. Stereodynamical Origin of Anti-Arrhenius Kinetics: Negative Activation Energy and Roaming for a Four-Atom Reaction. J Phys Chem Lett 2015; 6:1553-8. [PMID: 26263312 DOI: 10.1021/acs.jpclett.5b00384] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The OH + HBr → H2O + Br reaction, prototypical of halogen-atom liberating processes relevant to mechanisms for atmospheric ozone destruction, attracted frequent attention of experimental chemical kinetics: the nature of the unusual reactivity drop from low to high temperatures eluded a variety of theoretical efforts, ranking this one among the most studied four-atom reactions. Here, inspired by oriented molecular-beams experiments, we develop a first-principles stereodynamical approach. Thermalized sets of trajectories, evolving on a multidimensional potential energy surface quantum mechanically generated on-the-fly, provide a map of most visited regions at each temperature. Visualizations of rearrangements of bonds along trajectories and of the role of specific angles of reactants' mutual approach elucidate the mechanistic change from the low kinetic energy regime (where incident reactants reorient to find the propitious alignment leading to reaction) to high temperature (where speed hinders adjustment of directionality and roaming delays reactivity).
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Affiliation(s)
- Nayara D Coutinho
- †Unidade Universitária de Ciências Exatas e Tecnológicas, 75001-970, Anápolis, and Unidade de Ipameri, Ipameri, Universidade Estadual de Goiás, 75780-000 Goiás, Brazil
- ‡Instituto de Química, Universidade de Brasília, Caixa Postal 4478, 70904-970 Brasília, Brazil
| | - Valter H C Silva
- †Unidade Universitária de Ciências Exatas e Tecnológicas, 75001-970, Anápolis, and Unidade de Ipameri, Ipameri, Universidade Estadual de Goiás, 75780-000 Goiás, Brazil
| | - Heibbe C B de Oliveira
- ‡Instituto de Química, Universidade de Brasília, Caixa Postal 4478, 70904-970 Brasília, Brazil
| | - Ademir J Camargo
- †Unidade Universitária de Ciências Exatas e Tecnológicas, 75001-970, Anápolis, and Unidade de Ipameri, Ipameri, Universidade Estadual de Goiás, 75780-000 Goiás, Brazil
| | - Kleber C Mundim
- ‡Instituto de Química, Universidade de Brasília, Caixa Postal 4478, 70904-970 Brasília, Brazil
| | - Vincenzo Aquilanti
- §Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
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14
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Aoiz FJ, Brouard M, Gordon SDS, Nichols B, Stolte S, Walpole V. A new perspective: imaging the stereochemistry of molecular collisions. Phys Chem Chem Phys 2015; 17:30210-28. [DOI: 10.1039/c5cp03273c] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The concept of the steric effect plays a central role in chemistry. This Perspective describes how the polarization of reactant molecules in space can be used to probe directly the steric effect, and highlights some of the new measurements that are made possible by coupling reactant orientation and alignment with ion imaging techniques.
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Affiliation(s)
- F. J. Aoiz
- Departamento de Química Física
- Facultad de Química
- Universidad Complutense
- 28040 Madrid
- Spain
| | - M. Brouard
- The Department of Chemistry
- University of Oxford
- The Physical and Theoretical Chemistry Laboratory
- Oxford
- UK
| | - S. D. S. Gordon
- The Department of Chemistry
- University of Oxford
- The Physical and Theoretical Chemistry Laboratory
- Oxford
- UK
| | - B. Nichols
- The Department of Chemistry
- University of Oxford
- The Physical and Theoretical Chemistry Laboratory
- Oxford
- UK
| | - S. Stolte
- Institute of Atomic and Molecular Physics
- Jilin University
- Changchun 130012
- China
- Department of Physics and Astronomy
| | - V. Walpole
- The Department of Chemistry
- University of Oxford
- The Physical and Theoretical Chemistry Laboratory
- Oxford
- UK
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15
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de Oliveira-Filho AGS, Ornellas FR, Bowman JM. Energy disposal and thermal rate constants for the OH + HBr and OH + DBr reactions: quasiclassical trajectory calculations on an accurate potential energy surface. J Phys Chem A 2014; 118:12080-8. [PMID: 25365787 DOI: 10.1021/jp509430p] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report reaction cross sections, energy disposal, and rate constants for the OH + HBr → Br + H2O and OH + DBr → Br + HDO reactions from quasiclassical trajectory calculations using an ab initio potential energy surface [ de Oliveira-Filho , A. G. S. ; Ornellas , F. R. ; Bowman , J. M. J. Phys. Chem. Lett. 2014 , 5 , 706 - 712 ]. Comparison with available experiments are made and generally show good agreement.
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Affiliation(s)
- Antonio G S de Oliveira-Filho
- Departamento de Quı́mica Fundamental, Instituto de Quı́mica, Universidade de São Paulo , São Paulo 05508-000, Brazil
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16
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Roncaratti LF, Cappelletti D, Pirani F. The spontaneous synchronized dance of pairs of water molecules. J Chem Phys 2014; 140:124318. [PMID: 24697452 DOI: 10.1063/1.4869595] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Luiz F Roncaratti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - David Cappelletti
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Fernando Pirani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
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Kasai T, Che DC, Okada M, Tsai PY, Lin KC, Palazzetti F, Aquilanti V. Directions of chemical change: experimental characterization of the stereodynamics of photodissociation and reactive processes. Phys Chem Chem Phys 2014; 16:9776-90. [DOI: 10.1039/c4cp00464g] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Nakamura M, Che DC, Tsai PY, Lin KC, Kasai T. Alignment selection of the metastable CO(a 3Π1) molecule and the steric effect in the aligned CO(a 3Π1) + NO collision. J Phys Chem A 2013; 117:8157-62. [PMID: 23829701 DOI: 10.1021/jp401784k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aligned metastable CO(a (3)Π1) molecular beam was generated by an electronic excitation through the Cameron band (CO a (3)Π1 ← X (1)Σ(+)) transition. Beam characterization of the aligned molecular beam of CO(a (3)Π1) was carried out by (1 + 1) REMPI detection via the b (3)Σ(+) state. The REMPI signals showed the clear dependence on the polarization of the pump laser, and the experimental result was well reproduced by the theoretical simulation. This agreement confirms that aligned metastable CO(a (3)Π1) can be generated and controlled by rotating polarization of the pump laser. By using this technique, a single quantum state of CO(a (3)Π1) can be selected as a metastable molecular beam. The steric effect in the energy-transfer collision of CO(a (3)Π1) with NO forming the excited NO was carried out with this aligned CO(a (3)Π1) molecular beam. We find that the sideways orientation of CO(a (3)Π1) is more favorable in the formation of the excited NO(A (2)Σ(+), B (2)Π) than that for the axial collisions. The obtained steric effect was discussed with the aid of the spatial distribution of CO(a (3)Π1) molecular orbitals, and we find that specific rotational motion of CO(a (3)Π1) in each state may not be a dominant factor in this energy-transfer collision.
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Affiliation(s)
- Masaaki Nakamura
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
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Kasai T, Che DC, Tsai PY, Lin KC. Reaction Dynamics with Molecular Beams and Oriented Molecular Beams: A Tool for Looking Closer to Chemical Reactions and Photodissociations. J CHIN CHEM SOC-TAIP 2012. [DOI: 10.1002/jccs.201100735] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Tsai PY, Che DC, Nakamura M, Lin KC, Kasai T. Orientation dependence for Br formation in the reaction of oriented OH radical with HBr molecule. Phys Chem Chem Phys 2011; 13:1419-23. [DOI: 10.1039/c0cp01089h] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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