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Bhattacharyya D, Ramesh SG. Wavepacket dynamical study of H-atom tunneling in catecholate monoanion: the role of intermode couplings and energy flow. Phys Chem Chem Phys 2023; 25:1923-1936. [PMID: 36541267 DOI: 10.1039/d2cp03803j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We present a study of H-atom tunneling in catecholate monoanion through wavepacket dynamical simulations. In our earlier study of this symmetrical double-well system [Phys. Chem. Chem. Phys., 2022, 24, 10887], a limited number of transition state modes were identified as being important for the tunneling process. These include the imaginary frequency mode Q1, the CO scissor mode Q10, and the OHO bending mode Q29. In this work, starting from non-stationary initial states prepared with excitations in these modes, we have carried out wavepacket dynamics in two and three dimensional spaces. We analyse the dynamical effects of the intermode couplings, in particular the role of energy flow between the studied modes on H-atom tunneling. We find that while Q10 strongly modulates the donor-acceptor distance, it does not exchange energy with Q1. However, excitation in Q29 or Q1 does lead to rapid energy exchange between these modes, which modifies the tunneling rate at early times.
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Affiliation(s)
- Debabrata Bhattacharyya
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India.
| | - Sai G Ramesh
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India.
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2
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Zhelyazkova V, Martins FBV, Agner JA, Schmutz H, Merkt F. Multipole-moment effects in ion-molecule reactions at low temperatures: part I - ion-dipole enhancement of the rate coefficients of the He + + NH 3 and He + + ND 3 reactions at collisional energies Ecoll/ kB near 0 K. Phys Chem Chem Phys 2021; 23:21606-21622. [PMID: 34569565 PMCID: PMC8494273 DOI: 10.1039/d1cp03116c] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 09/02/2021] [Indexed: 11/29/2022]
Abstract
The energy dependence of the rates of the reactions between He+ and ammonia (NY3, Y = {H,D}), forming NY2+, Y and He as well as NY+, Y2 and He, and the corresponding product branching ratios have been measured at low collision energies Ecoll between 0 and kB·40 K using a recently developed merged-beam technique [Allmendinger et al., ChemPhysChem, 2016, 17, 3596]. To avoid heating of the ions by stray electric fields, the reactions are observed within the large orbit of a highly excited Rydberg electron. A beam of He Rydberg atoms was merged with a supersonic beam of ammonia using a curved surface-electrode Rydberg-Stark deflector, which is also used for adjusting the final velocity of the He Rydberg atoms, and thus the collision energy. A collision-energy resolution of about 200 mK was reached at the lowest Ecoll values. The reaction rate coefficients exhibit a sharp increase at collision energies below ∼kB·5 K and pronounced deviations from Langevin-capture behaviour. The experimental results are interpreted in terms of an adiabatic capture model describing the rotational-state-dependent orientation of the ammonia molecules by the electric field of the He+ atom. The model faithfully describes the experimental observations and enables the identification of three classes of |JKMp〉 rotational states of the ammonia molecules showing different low-energy capture behaviour: (A) high-field-seeking states with |KM| ≥ 1 correlating to the lower component of the umbrella-motion tunnelling doublet at low fields. These states undergo a negative linear Stark shift, which leads to strongly enhanced rate coefficients; (B) high-field-seeking states subject to a quadratic Stark shift at low fields and which exhibit only weak rate enhancements; and (C) low-field-seeking states with |KM| ≥ 1. These states exhibit a positive Stark shift at low fields, which completely suppresses the reactions at low collision energies. Marked differences in the low-energy reactivity of NH3 and ND3-the rate enhancements in ND3 are more pronounced than in NH3-are quantitatively explained by the model. They result from the reduced magnitudes of the tunnelling splitting and rotational intervals in ND3 and the different occupations of the rotational levels in the supersonic beam caused by the different nuclear-spin statistical weights. Thermal capture rate constants are derived from the model for the temperature range between 0 and 10 K relevant for astrochemistry. Comparison of the calculated thermal capture rate coefficients with the absolute reaction rates measured above 27 K by Marquette et al. (Chem. Phys. Lett., 1985, 122, 431) suggests that only 40% of the close collisions are reactive.
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3
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Wichmann G, Miloglyadov E, Seyfang G, Quack M. Nuclear spin symmetry conservation studied by cavity ring-down spectroscopy of ammonia in a seeded supersonic jet from a pulsed slit nozzle. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1752946] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- G. Wichmann
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - E. Miloglyadov
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - G. Seyfang
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - M. Quack
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
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4
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Fábri C, Marquardt R, Császár AG, Quack M. Controlling tunneling in ammonia isotopomers. J Chem Phys 2019; 150:014102. [DOI: 10.1063/1.5063470] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Csaba Fábri
- Laboratory of Molecular Structure and Dynamics, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary
- MTA-ELTE Complex Chemical Systems Research Group, P.O. Box 32, H-1518 Budapest 112, Hungary
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Roberto Marquardt
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
- Laboratoire de Chimie Quantique, Institut de Chimie UMR 7177 CNRS/Université de Strasbourg, 4, Rue Blaise Pascal CS 90032, 67081 Strasbourg Cedex, France
| | - Attila G. Császár
- Laboratory of Molecular Structure and Dynamics, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary
- MTA-ELTE Complex Chemical Systems Research Group, P.O. Box 32, H-1518 Budapest 112, Hungary
| | - Martin Quack
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
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5
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Abstract
Dielectric barrier discharge (DBD) plasmas and plasma catalysis are becoming an alternative procedure to activate various gas phase reactions. A low-temperature and normal operating pressure are the main advantages of these processes, but a limited energy efficiency and little selectivity control hinder their practical implementation. In this work, we propose the use of isotope labelling to retrieve information about the intermediate reactions that may intervene during the DBD processes contributing to a decrease in their energy efficiency. The results are shown for the wet reforming reaction of methane, using D2O instead of H2O as reactant, and for the ammonia synthesis, using NH3/D2/N2 mixtures. In the two cases, it was found that a significant amount of outlet gas molecules, either reactants or products, have deuterium in their structure (e.g., HD for hydrogen, CDxHy for methane, or NDxHy for ammonia). From the analysis of the evolution of the labelled molecules as a function of power, useful information has been obtained about the exchange events of H by D atoms (or vice versa) between the plasma intermediate species. An evaluation of the number of these events revealed a significant progression with the plasma power, a tendency that is recognized to be detrimental for the energy efficiency of reactant to product transformation. The labelling technique is proposed as a useful approach for the analysis of plasma reaction mechanisms.
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6
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Butkovskaya NI, Setser DW. Infrared Chemiluminescence Study of the Reaction of Hydroxyl Radical with Formamide and the Secondary Unimolecular Reaction of Chemically Activated Carbamic Acid. J Phys Chem A 2018; 122:3735-3746. [PMID: 29614222 DOI: 10.1021/acs.jpca.8b01512] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reactions of OH and OD radicals with NH2CHO and ND2CHO were studied by Fourier transform infrared emission spectroscopy of the product molecules from a fast-flow reactor at 298 K. Vibrational distributions of the HOD and H2O molecules from the primary reactions with the C-H bond were obtained by computer simulation of the emission spectra. The vibrational distributions resemble those for other direct H atom abstraction reactions, such as with acetaldehyde. The highest observed level gives an estimate of the C-H bond dissociation energy in formamide of 90.5 ± 1.3 kcal mol-1. Observation of CO2, ammonia, and secondary water chemiluminescence gave evidence that recombination of OH and NH2CO forms carbamic acid (NH2COOH) with excitation energy of 103 kcal mol-1, which decomposes through two pathways forming either NH3 + CO2 or H2O + HNCO. The branching fraction for ammonia formation was estimated to be 2-3 times larger than formation of water. This observation was confirmed by RRKM calculation of the decomposition rate constants. A new simulation method was developed to analyze infrared emission from NH3, NH2D, ND2H, and ND3. Dynamical aspects of the primary and secondary reactions are discussed based on the vibrational distributions of CO2 and those of H/D isotopes of water and ammonia.
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Affiliation(s)
- N I Butkovskaya
- Semenov Institute of Chemical Physics, Russian Academy of Sciences , 119991 Moscow , Russian Federation
| | - D W Setser
- Department of Chemistry , Kansas State University , Manhattan , Kansas 66506 , United States
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7
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Chang CH, Nesbitt DJ. Sub-Doppler slit jet infrared spectroscopy of astrochemically relevant cations: Symmetric (ν1) and antisymmetric (ν6) NH stretching modes in ND2H2+. J Chem Phys 2018; 148:014304. [PMID: 29306286 DOI: 10.1063/1.5003230] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Chih-Hsuan Chang
- JILA, National Institute of Standards and Technology, University of Colorado, and Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - David J. Nesbitt
- JILA, National Institute of Standards and Technology, University of Colorado, and Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309, USA
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8
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Császár AG, Furtenbacher T. Promoting and inhibiting tunneling via nuclear motions. Phys Chem Chem Phys 2016; 18:1092-104. [PMID: 26660142 DOI: 10.1039/c5cp04270d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Accurate, experimental rotational-vibrational energy levels determined via the MARVEL (Measured Active Rotational-Vibrational Energy Levels) algorithm and published recently for the symmetric-top (14)NH3 molecule in J. Quant. Spectrosc. Radiat. Transfer, 2015, 116, 117-130 are analyzed to unravel the promoting and inhibiting effects of vibrations and rotations on the tunneling splittings of the corresponding symmetric (s) and antisymmetric (a) rovibrational energy level pairs. The experimental transition data useful from the point of view of the present analysis cover the range 0.7-7000 cm(-1), sufficiently detailed rovibrational energy sets worth analyzing are available for 20 vibrational bands. The highest J value, where J stands for the rotational quantum number, within the experimental dataset employed is 30. Coupling of the "umbrella" motion of (14)NH3 with other vibrational degrees of freedom has only a minor effect on the a-s tunneling splitting characterizing the ground vibrational state, 0.79436(70) cm(-1). In the majority of the cases rotation around the C3 axis increases, while rotation around the two perpendicular axes decreases the tunneling splittings. For example, for the pair of vibrational ground states, 0(+) and 0(-), the tunneling splitting basically disappears at around J = 25 for the (J,K) = (J,1) states, where K = |k| is the usual quantum number characterizing the projection of the rotational angular momentum on the principal axis. The tunneling splittings, defined as energy differences E(a) - E(s) of corresponding energy level pairs, as a function of J and K show a very regular behavior for the ground state (GS) and the nν2 bands. For the other bands investigated exceptions from a regular behavior do occur, especially for bands characterized by degenerate vibrations, and occasionally the data available are not sufficient to arrive at definitive conclusions. The most irregular behavior is observed for rotational states characterized by the k - l = 3n rule (l is the vibrational angular momentum quantum number), with n = 0, 1, 2,… High-quality, variationally computed rovibrational data support all the conclusions of this study based on experimental energy levels.
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Affiliation(s)
- Attila G Császár
- Institute of Chemistry, Loránd Eötvös University, Pázmány sétány 1/A, Hungary and MTA-ELTE Complex Chemical Systems Research Group, H-1518 Budapest 112, P. O. Box 32, H-1117 Budapest, Hungary.
| | - Tibor Furtenbacher
- Institute of Chemistry, Loránd Eötvös University, Pázmány sétány 1/A, Hungary and MTA-ELTE Complex Chemical Systems Research Group, H-1518 Budapest 112, P. O. Box 32, H-1117 Budapest, Hungary.
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9
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Dietiker P, Miloglyadov E, Quack M, Schneider A, Seyfang G. Infrared laser induced population transfer and parity selection in 14NH3: A proof of principle experiment towards detecting parity violation in chiral molecules. J Chem Phys 2015; 143:244305. [DOI: 10.1063/1.4936912] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- P. Dietiker
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - E. Miloglyadov
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - M. Quack
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - A. Schneider
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
| | - G. Seyfang
- Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland
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10
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Zanzoni S, Pedroni M, D'Onofrio M, Speghini A, Assfalg M. Paramagnetic Nanoparticles Leave Their Mark on Nuclear Spins of Transiently Adsorbed Proteins. J Am Chem Soc 2015; 138:72-5. [PMID: 26683352 DOI: 10.1021/jacs.5b11582] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The successful application of nanomaterials in biosciences necessitates an in-depth understanding of how they interface with biomolecules. Transient associations of proteins with nanoparticles (NPs) are accessible by solution NMR spectroscopy, albeit with some limitations. The incorporation of paramagnetic centers into NPs offers new opportunities to explore bio-nano interfaces. We propose NMR paramagnetic relaxation enhancement as a new tool to detect NP-binding surfaces on proteins with increased sensitivity, also extending the applicability of NMR investigations to heterogeneous biomolecular mixtures. The adsorption of ubiquitin on gadolinium-doped fluoride-based NPs produced residue-specific NMR line-broadening effects mapping to a contiguous area on the surface of the protein. Importantly, an identical paramagnetic fingerprint was observed in the presence of a competing protein-protein association equilibrium, exemplifying possible interactions taking place in crowded biological media. The interaction was further characterized using isothermal titration calorimetry and upconversion emission measurements. The data indicate that the used fluoride-based NPs are not biologically inert but rather are capable of biomolecular recognition.
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Affiliation(s)
- Serena Zanzoni
- Biomolecular NMR Laboratory, Department of Biotechnology, University of Verona , 37134 Verona, Italy
| | - Marco Pedroni
- Nanomaterials Research Group, Department of Biotechnology, University of Verona and INSTM , 37134 Verona, Italy
| | - Mariapina D'Onofrio
- Biomolecular NMR Laboratory, Department of Biotechnology, University of Verona , 37134 Verona, Italy
| | - Adolfo Speghini
- Nanomaterials Research Group, Department of Biotechnology, University of Verona and INSTM , 37134 Verona, Italy
| | - Michael Assfalg
- Biomolecular NMR Laboratory, Department of Biotechnology, University of Verona , 37134 Verona, Italy
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11
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Tkáč O, Orr-Ewing AJ, Dagdigian PJ, Alexander MH, Onvlee J, van der Avoird A. Collision dynamics of symmetric top molecules: a comparison of the rotationally inelastic scattering of CD3 and ND3 with He. J Chem Phys 2014; 140:134308. [PMID: 24712794 DOI: 10.1063/1.4869596] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We compare rotationally inelastic scattering of deuterated methyl radicals (CD3) and ammonia (ND3) in collisions with helium using close-coupling quantum-mechanical scattering calculations performed with ab initio potential energy surfaces (PESs). The theoretical methods have been rigorously tested against angle-resolved experimental measurements obtained using crossed molecular beam apparatuses in combination with velocity map imaging [O. Tkáč, A. G. Sage, S. J. Greaves, A. J. Orr-Ewing, P. J. Dagdigian, Q. Ma, and M. H. Alexander, Chem. Sci. 4, 4199 (2013); O. Tkáč, A. K. Saha, J. Onvlee, C.-H. Yang, G. Sarma, C. K. Bishwakarma, S. Y. T. van de Meerakker, A. van der Avoird, D. H. Parker, and A. J. Orr-Ewing, Phys. Chem. Chem. Phys. 16, 477 (2014)]. Common features of the scattering dynamics of these two symmetric top molecules, one closed-shell and the other an open-shell radical, are identified and discussed. Two types of anisotropies in the PES influence the interaction of an atom with a nonlinear polyatomic molecule. The effects of these anisotropies can be clearly seen in the state-to-state integral cross sections out of the lowest CD3 rotational levels of each nuclear spin symmetry at a collision energy of 440 cm(-1). Similarities and differences in the differential cross sections for the ND3-He and CD3-He systems can be linked to the coupling terms derived from the PESs which govern particular initial to final rotational level transitions.
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Affiliation(s)
- Ondřej Tkáč
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Paul J Dagdigian
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218-2685, USA
| | - Millard H Alexander
- Department of Chemistry and Biochemistry and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2021, USA
| | - Jolijn Onvlee
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525AJ Nijmegen, The Netherlands
| | - Ad van der Avoird
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525AJ Nijmegen, The Netherlands
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12
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Ruzi M, Anderson DT. Matrix isolation spectroscopy and nuclear spin conversion of NH3 and ND3 in solid parahydrogen. J Phys Chem A 2013; 117:9712-24. [PMID: 23594210 DOI: 10.1021/jp3123727] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present matrix isolation infrared absorption spectra of NH3 and ND3 trapped in solid parahydrogen (pH2) at temperatures around 1.8 K. We used the relatively slow nuclear spin conversion (NSC) of NH3 and ND3 in freshly deposited pH2 samples as a tool to assign the sparse vibration-inversion-rotation (VIR) spectra of NH3 in the regions of the ν2, ν4, 2ν4, ν1, and ν3 bands and ND3 in the regions of the ν2, ν4, ν1, and ν3 fundamentals. Partial assignments are also presented for various combination bands of NH3. Detailed analysis of the ν2 bands of NH3 and ND3 indicates that both isotopomers are nearly free rotors; that the vibrational energy is blue-shifted by 1-2%; and that the rotational constants and inversion tunneling splitting are 91-94% and 67-75%, respectively, of the gas-phase values. The line shapes of the VIR absorptions are narrow (0.2-0.4 cm(-1)) for upper states that cannot rotationally relax and broad (>1 cm(-1)) for upper states that can rotationally relax. We report and assign a number of NH3-induced infrared absorption features of the pH2 host near 4150 cm(-1), along with a cooperative transition that involves simultaneous vibrational excitation of a pH2 molecule and rotation-inversion excitation of NH3. The NSCs of NH3 and ND3 were found to follow first-order kinetics with rate constants at 1.8 K of k = 1.88(16) × 10(-3) s(-1) and k = 1.08(8) × 10(-3) s(-1), respectively. These measured rate constants are compared to previous measurements for NH3 in an Ar matrix and with the rate constants measured for other dopant molecules isolated in solid pH2.
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Affiliation(s)
- Mahmut Ruzi
- Department of Chemistry, University of Wyoming , Laramie, Wyoming 82071, United States
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13
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Marquardt R, Sagui K, Zheng J, Thiel W, Luckhaus D, Yurchenko S, Mariotti F, Quack M. Global Analytical Potential Energy Surface for the Electronic Ground State of NH3 from High Level ab Initio Calculations. J Phys Chem A 2013; 117:7502-22. [DOI: 10.1021/jp4016728] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Roberto Marquardt
- Laboratoire de Chimie Quantique, Institut de Chimie UMR 7177 CNRS/Université de Strasbourg, 1 rue Blaise Pascal, BP 296/R8, Strasbourg CEDEX, France
| | - Kenneth Sagui
- Laboratoire
de Chimie Theorique, Université de Marne-la-Vallée 5 Bd Descartes (Champs-sur-Marne), F-77454 Marne-la-Vallée
Cedex 2, France
| | - Jingjing Zheng
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Walter Thiel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - David Luckhaus
- Chemistry Department, University of British Columbia, 6174 University Boulevard, Vancouver,
BC V6T 1Z3, Canada
| | - Sergey Yurchenko
- Department
of Physics and Astronomy, University College London, London, WC1E 6BT, U.K
| | - Fabio Mariotti
- Laboratorium für Physikalische Chemie, ETH Zürich
Wolfgang Pauli Str. 10, CH-8093 Zürich, Switzerland
| | - Martin Quack
- Laboratorium für Physikalische Chemie, ETH Zürich
Wolfgang Pauli Str. 10, CH-8093 Zürich, Switzerland
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14
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Li YQ, Song YZ, Song P, Li YZ, Ding Y, Sun MT, Ma FC. Ab initio-based double many-body expansion potential energy surface for the first excited triplet state of the ammonia molecule. J Chem Phys 2012; 136:194705. [PMID: 22612107 DOI: 10.1063/1.4718705] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A global single-sheeted double many-body expansion potential energy surface is reported for the first excited triplet state of NH(3). It employs an approximate cluster expansion of the molecular potential that utilizes previously reported functions of the same family for the triatomic fragments. Four-body energy terms have been calibrated from extensive accurate ab initio data so as to reproduce the main features of the title system. A new switching function formalism has been reported to approximate the true multisheeted nature of NH(3)((3)A(2) ('')) potential energy surface, thus allowing the correct behavior at the NH(2)((2)A(")) + H((2)S) and NH(2)((4)A(")) + H((2)S) dissociation limits. The resulting fully six-dimensional potential energy function reproduces the correct symmetry under the permutation of identical atoms, and predicts the correct behavior at all dissociation channels while providing a realistic representation at all interatomic separations. The major attributes of the NH(3) double many-body expansion potential energy surface have also been characterized, and found to be in good agreement, both with the calculated ones from the raw ab initio energies and the theoretical results available in the literature.
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Affiliation(s)
- Y Q Li
- Department of Physics, Liaoning University, Shenyang 110036, China.
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15
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Huang X, Schwenke DW, Lee TJ. Rovibrational spectra of ammonia. II. Detailed analysis, comparison, and prediction of spectroscopic assignments for 14NH3,15NH3, and 14ND3. J Chem Phys 2011; 134:044321. [DOI: 10.1063/1.3541352] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Li YQ, Varandas AJC. Ab-Initio-Based Global Double Many-Body Expansion Potential Energy Surface for the Electronic Ground State of the Ammonia Molecule. J Phys Chem A 2010; 114:6669-80. [DOI: 10.1021/jp1019685] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Y. Q. Li
- Departamento de Química, Universidade de Coimbra 3004-535 Coimbra, Portugal
| | - A. J. C. Varandas
- Departamento de Química, Universidade de Coimbra 3004-535 Coimbra, Portugal
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17
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Snels M, Hollenstein H, Quack M. Mode selective tunneling dynamics observed by high resolution spectroscopy of the bending fundamentals of N14H2D and N14D2H. J Chem Phys 2006; 125:194319. [PMID: 17129115 DOI: 10.1063/1.2366704] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High resolution (0.004 and 0.01 cm(-1) instrumental bandwidth) interferometric Fourier transform infrared spectra of (14)NH2D and (14)ND2H were measured on a Bomem DA002 spectrometer in a supersonic jet expansion and at room temperature. We report the analysis of the bending fundamentals of (14)NH2D with term values Tv(s)=1389.9063(2) cm(-1) and Tv(a)=1390.4953(2) cm(-1) for the nu(4b) fundamental and Tv(s)=1605.6404(7) cm(-1) and Tv(a)=1591.0019(7) cm(-1) for the nu(4a) fundamental, and of (14)ND2H with term values of Tv(s)=1233.3740(2) cm(-1) and Tv(a)=1235.8904(2) cm(-1) for the nu(4a) fundamental and Tv(s)=1461.7941(9) cm(-1) and Tv(a)=1461.9918(19) cm(-1) for the nu(4b) fundamental. In all cases Tv(s) gives the position of the symmetric inversion sublevel (with positive parity) and Tv(a) the position of the antisymmetric inversion sublevel (with negative parity). The notation for the fundamentals nu(4a) and nu(4b) is chosen by correlation with the degenerate nu(4) mode in the C(3v) symmetric molecules NH3 and ND3. The degeneracy is lifted in Cs symmetry and a indicates the symmetric, b the antisymmetric normal mode with respect to the Cs symmetry plane in NH2D and ND2H. Assignments were established with certainty by means of ground state combination differences. About 20 molecular parameters of the effective S-reduced Hamiltonian could be determined accurately for each fundamental. In particular, the effect of Fermi resonances of the 2nu(2) overtone with the nu(4a) bending mode was observed, leading to an increased inversion splitting in the case of ND2H and to a strongly increased inversion splitting and an inverted order of the two inversion levels in NH2D. Rotational perturbations observed with the nu(4b) bending fundamentals are probably due to Coriolis interactions with the inversion overtone 2nu(2). The results are important for understanding isotope effects on the inversion in ammonia as well as its selective catalysis and inhibition by excitation of different vibrational modes, as treated by quantum dynamics on high dimensional potential hypersurfaces of this molecule.
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Affiliation(s)
- Marcel Snels
- Istituto di Scienze dell'Atmosfera e del Clima (ISAC), Sezione di Roma, Consiglio Nazionale delle Ricerche (CNR), Via del Fosso del Cavaliere 100, I-00133 Roma, Italy
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Marquardt R, Sagui K, Klopper W, Quack M. Global Analytical Potential Energy Surface for Large Amplitude Nuclear Motions in Ammonia. J Phys Chem B 2005; 109:8439-51. [PMID: 16851991 DOI: 10.1021/jp0507243] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An analytical, full-dimensional, and global representation of the potential energy surface of NH(3) in the lowest adiabatic electronic state is developed, and parameters are determined by adjustment to ab initio data and thermochemical data for several low-lying dissociation channels. The electronic structure is calculated at the CASPT2 level within an [8,7] active space. The representation is compared to other recently published potential energy surfaces for this molecule. The present representation is distinguished by giving a qualitatively correct description of the potential energy for very large amplitude displacements of the nuclei from equilibrium. Other characteristic features of the present surface are the equilibrium geometries r(eq)(NH(3)) approximately 101.24 pm, r(eq)(NH(2)) approximately 102.60 pm, alpha(eq)(NH(3)) approximately 106.67 degrees, and the inversion barrier at r(inv)(NH(3)) approximately 99.80 pm and 1781 cm(-1) above the NH(3) minimum. The barrier to linearity in NH(2) is 11,914 cm(-1) above the NH(2)((2)B(1)) minimum. While the quartic force field for NH(3) from the present representation is significantly different from that of the other potential energy surfaces, the vibrational structures obtained from perturbation theory are quite similar for all representations studied here.
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Affiliation(s)
- Roberto Marquardt
- Laboratoire de Chimie Théorique, Université de Marne-la-Vallée, 5, Bd Descartes, Champs sur Marne, F-77454 Marne-la-Vallée Cedex 2, France.
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Marquardt R, Quack M, Thanopulos I, Luckhaus D. A global electric dipole function of ammonia and isotopomers in the electronic ground state. J Chem Phys 2003. [DOI: 10.1063/1.1617272] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Snels M, Hollenstein H, Quack M. The NH and ND stretching fundamentals of14ND2H. J Chem Phys 2003. [DOI: 10.1063/1.1592506] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Rajamäki T, Miani A, Halonen L. Vibrational energy levels for symmetric and asymmetric isotopomers of ammonia with an exact kinetic energy operator and new potential energy surfaces. J Chem Phys 2003. [DOI: 10.1063/1.1555801] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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22
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Marquardt R, Quack M, Thanopulos I, Luckhaus D. Tunneling dynamics of the NH chromophore in NHD2 during and after coherent infrared excitation. J Chem Phys 2003. [DOI: 10.1063/1.1514577] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Roberto Marquardt
- Laboratoire de Chimie Théorique, Université de Marne-la-Vallée, 5 Bd Descartes (Champs-sur-Marne), F-77454 Marne-la-Vallée Cedex 2, France
| | - Martin Quack
- Physical Chemistry, ETH Zürich, CH-8093-Zürich, Switzerland
| | | | - David Luckhaus
- Institut für Physikalische Chemie, Universität Göttingen, Tammanstrasse 6, D-37077 Göttingen, Germany
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Lin H, Thiel W, Yurchenko SN, Carvajal M, Jensen P. Vibrational energies for NH3 based on high level ab initio potential energy surfaces. J Chem Phys 2002. [DOI: 10.1063/1.1521762] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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