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Albert S, Bauerecker S, Bekhtereva ES, Bolotova IB, Hollenstein H, Quack M, Ulenikov ON. High resolution FTIR spectroscopy of fluoroform 12CHF3 and critical analysis of the infrared spectrum from 25 to 1500 cm−1. Mol Phys 2018. [DOI: 10.1080/00268976.2017.1392628] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- S. Albert
- Physical Chemistry, ETH-Zürich, Zürich, Switzerland
| | - S. Bauerecker
- Physical Chemistry, ETH-Zürich, Zürich, Switzerland
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, Braunschweig, Germany
| | - E. S. Bekhtereva
- Physical Chemistry, ETH-Zürich, Zürich, Switzerland
- Institute of Physics and Technology, National Research Tomsk Polytechnic University, Tomsk, Russia
| | | | | | - M. Quack
- Physical Chemistry, ETH-Zürich, Zürich, Switzerland
| | - O. N. Ulenikov
- Physical Chemistry, ETH-Zürich, Zürich, Switzerland
- Institute of Physics and Technology, National Research Tomsk Polytechnic University, Tomsk, Russia
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Albert S, Bekhtereva E, Bolotova I, Chen Z, Fábri C, Hollenstein H, Quack M, Ulenikov O. Isotope effects on the resonance interactions and vibrational quantum dynamics of fluoroform 12,13CHF 3. Phys Chem Chem Phys 2017; 19:26527-26534. [PMID: 28956885 DOI: 10.1039/c7cp04762b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a comparison of the analysis of the low energy spectrum of 13CHF3 and 12CHF3 from the THz (FIR) range to the ν1 fundamental at high resolution (δ[small nu, Greek, tilde] < 0.001 cm-1 or otherwise Doppler limited) on the basis of FTIR spectra taken both with ordinary light sources and with the synchrotron radiation from the Swiss Light Source. Several vibrational levels are accurately determined including, in particular, the 2ν4 CH-bending overtone and the ν1 CH-stretching fundamental of 13CHF3. Comparison of experimental results with those from accurate full dimensional vibrational calculations allows for a study of the time-dependent quantum dynamics of intramolecular vibrational redistribution (IVR) in the CH chromophore both on short time scales (fs) and longer time scales (ps) when coupling to the lower frequency modes becomes important and where the 12C/13C isotope effects are very large.
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Affiliation(s)
- Sieghard Albert
- Physical Chemistry, ETH-Zürich, CH-8093, Zürich, Switzerland.
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3
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Influence of kinetic coupling in rectilinear coordinates on the vibrational spectrum of fluoroform. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.10.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Yokoyama A, Katsumata K, Ohba H, Akagi H, Saeki M, Yokoyama K. Isotopically Selective Infrared Multiphoton Dissociation of 2,3-Dihydropyran. J Phys Chem A 2008; 112:6571-7. [DOI: 10.1021/jp802101h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Atsushi Yokoyama
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, Shirakata 2-4, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Keiichi Katsumata
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, Shirakata 2-4, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Hironori Ohba
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, Shirakata 2-4, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Hiroshi Akagi
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, Shirakata 2-4, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Morihisa Saeki
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, Shirakata 2-4, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Keiichi Yokoyama
- Quantum Beam Science Directorate, Japan Atomic Energy Agency, Shirakata 2-4, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
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Bossart R, Boyarkin OV, Makarov AA, Rizzo TR. Isotopically selective collisional vibrational energy transfer in CF3H. J Chem Phys 2007; 126:054302. [PMID: 17302472 DOI: 10.1063/1.2433946] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The authors investigate here the mechanism of collisionally enhanced isotopic selectivity observed in infrared multiple photon dissociation (IRMPD) of vibrationally preexcited CF3H by Boyarkin et al. [J. Chem. Phys. 118, 93 (2003)]. For both the carbon-12 and carbon-13 isotopic species they measure the dependence of the IRMPD yield on the time delay between the preexcitation and the dissociation pulses at different dissociation frequencies as well as its dependence on the initial isotopic composition of the sample. The results reveal that the collisional increase in isotopic selectivity originates not only from that of IRMPD itself but also from the isotopic selectivity of vibrational energy transfer, with the latter making the major contribution under their experimental conditions. They suggest that the observed isotopic selectivity in collisional energy transfer arises from the difference in overlap between the absorption spectra of the nu5 mode in the 12CF3H acceptor molecule with emission spectra of the same mode in the two isotopically different donors. Understanding the origin of this collisional effect has important implications for optimization of laser isotope separation processes.
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Affiliation(s)
- R Bossart
- Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland
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Pasin G, Gatti F, Iung C, Meyer HD. Theoretical investigation of intramolecular vibrational energy redistribution in highly excited HFCO. J Chem Phys 2006; 124:194304. [PMID: 16729811 DOI: 10.1063/1.2192499] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The present paper is devoted to the simulations of the intramolecular vibrational energy redistribution (IVR) in HFCO initiated by an excitation of the out-of-plane bending vibration [nnu(6)=2,4,6,...,18,20]. Using a full six-dimensional ab initio potential energy, the multiconfiguration time-dependent Hartree (MCTDH) method was exploited to propagate the corresponding six-dimensional wave packets. This study emphasizes the stability of highly excited states of the out-of-plane bending mode which exist even above the dissociation threshold. More strikingly, the structure of the IVR during the first step of the dynamics is very stable for initial excitations ranging from 2nu(6) to 20nu(6). This latter result is consistent with the analysis of the eigenstates obtained, up to 10nu(6), with the aid of the Davidson algorithm in a foregoing paper [Iung and Ribeiro, J. Chem. Phys. 121, 174105 (2005)]. The present study can be considered as complementary to this previous investigation. This paper also shows how MCTDH can be used to predict the dynamical behavior of a strongly excited system and to determine the energies of the corresponding highly excited states.
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Affiliation(s)
- Gauthier Pasin
- LSDSMS (UMR 5636-CNRS), CC 014, Université Montpellier II, F-34095 Montpellier Cedex 05, France.
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Iung C, Ribeiro F, Sibert EL. Comparison of Perturbative and Variational Treatments of Molecular Vibrations: Application to the Vibrational Spectrum of HFCO up to 8000 cm-1†. J Phys Chem A 2006; 110:5420-9. [PMID: 16623470 DOI: 10.1021/jp056937+] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We calculated highly excited states of the HFCO molecule, comparing results from two methods. In the first method, Van Vleck perturbation theory is used to transform away all off-diagonal couplings except those between nearly degenerate states. This perturbative transformation leads to a matrix representation where eigenvalues are obtained with relatively small matrices. In the second method, variational eigenvalues are obtained by combining the Jacobi-Wilson approach with the block-Davidson scheme. The key ingredient here is a prediagonalized-perturbative scheme applied to a subspace of a curvilinear normal-mode basis set. Comparisons of the two methods provide a critical test of the less time-consuming perturbation theory. Two different coordinate sets are used to test the sensitivity of the results to coordinate choice. Perturbation theory also requires a polynomial fit to the potential. The implications of this restriction are investigated.
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Affiliation(s)
- Christophe Iung
- Laboratoire de Structure et Dynamique des Systèmes Moléculaires et Solides (LSDSMS) Unité Mixte de Recherche (UMR-CNRS 5636)-CC 014, Université Montpellier II, 34095 Montpellier, Cedex 05, France.
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Iung C, Ribeiro F. Calculation of specific, highly excited vibrational states based on a Davidson scheme: Application to HFCO. J Chem Phys 2005; 123:174105. [PMID: 16375515 DOI: 10.1063/1.2101457] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We present the efficiency of a new modified Davidson scheme which yields selectively one high-energy vibrationally excited eigenstate or a series of eigenstates. The calculation of a highly vibrationally excited state psi located in a dense part of the spectrum requires a specific prediagonalization step before the Davidson scheme. It consists in building a small active space P containing the zero-order states which are coupled with the zero-order description of the eigenstate of interest. We propose a general way to define this active space P which plays a crucial role in the method. The efficiency of the method is illustrated by computing and analyzing the high-energy excited overtones of the out-of-plane mode [formula: see text] in HFCO. These overtone energies correspond to the 234th, 713th, and 1774th energy levels in our reference basis set which contains roughly 140,000 states. One of the main advantages of this Davidson scheme comes from the fact that the eigenstate and eigenvalue convergence can be assessed during the iterations by looking at the residual [formula: see text]. The maximum value epsilon allowed for this residual constitutes a very sensitive and efficient parameter which sets the accuracy of the eigenvalues and eigenstates, even when the studied states are highly excited and are localized in a dense part of the spectrum. The physical analysis of the eigenstates associated with the 5th, 7th, and 9th out-of-plane overtones in HFCO provides some interesting information on the energy localization in this mode and on the role played by the in-plane modes. Also, it provides some ideas on the numerical methods which should be developed in the future to tackle higher-energy excited states in polyatomics.
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Affiliation(s)
- Christophe Iung
- LSDSMS (UMR 5636), CC 014, Université Montpellier II, 34095 Montpellier Cedex 05, France.
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Ribeiro F, Iung C, Leforestier C. A Jacobi-Wilson description coupled to a block-Davidson algorithm: An efficient scheme to calculate highly excited vibrational levels. J Chem Phys 2005; 123:054106. [PMID: 16108630 DOI: 10.1063/1.1997129] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a new approach based on the block-Davidson scheme which provides eigenvalues and eigenvectors of highly excited (ro) vibrational states of polyatomic molecules. The key ingredient is a prediagonalized-perturbative scheme applied to a subspace of a curvilinear normal-mode basis set. This approach is coupled to the Jacobi vector description recently developed by our group [C. Leforestier, A. Viel, F. Gatti, C. Munoz, and C. Iung, J. Chem. Phys. 114, 2099 (2001)], and applied to the HFCO and H2CO molecules, which represent the main difficulties of such calculations for any available method. The first one presents a significant state density because of its low symmetry and the presence of a fluorine atom, while strong resonances and intermode couplings occur in H2CO. This study establishes the robustness, the numerical efficiency, and the versatility of the method which is compared to the regular Lanczos and Davidson schemes. It is also shown that the eigenvectors can be obtained within a given accuracy easily set by the user. This point constitutes one of the main advantages of the method as very few potential-energy surfaces achieve an accuracy of the order of a wave number for highly excited states. Furthermore, this method allows one to restrict the calculations to selected energy levels based on their zero-order descriptions.
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Affiliation(s)
- Fabienne Ribeiro
- Laboratoire de Structure et Dynamique des Systèmes Moléculaires et Solides Unite Mixte de Recherche (UMR-CNRS 5636)-CC 014, Université Montpellier II, 34095 Montpellier, Cedex 05, France
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Joyeux M. Study of vibrational energy localization and redistribution in hydrogen peroxide H2O2 at low energy. J Chem Phys 2005; 122:074303. [PMID: 15743228 DOI: 10.1063/1.1850894] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vibrational energy localization and/or redistribution in hydrogen peroxide H2O2 is studied at about 4000 cm(-1) above the quantum mechanical ground state using the ab initio potential energy surface of Koput, Carter, and Handy [J. Phys. Chem. A 102, 6325 (1998)]. In this work, the recently derived canonical perturbation procedure for floppy molecules serves two purposes. First, from the quantum mechanical point of view, it is shown that the energies of the lowest 130 states are reproduced with an average error smaller than 1.5 cm(-1) by a two-dimensional Hamiltonian, which is a function of the torsion and OO-stretch coordinates and momenta, while the other four degrees of freedom contribute only through powers of good quantum numbers. Moreover, the canonical perturbation procedure is also used in classical mechanics calculations, in order to define meaningful local modes, for which the ingoing and outgoing energy flows are monitored. Almost all the individual trajectories launched on the ab initio surface display the same behavior, that is, the superposition of (a) rapid (few hundreds of femtoseconds) and quasiperiodic energy exchanges between the two OH stretches and between the torsion and OO-stretch, and (b) slower (few to several picoseconds) but erratic-looking energy flows between all degrees of freedom. When averaging over large numbers of trajectories with the same local mode energies at time t=0, one observes instead a smooth and irreversible energy flow between all degrees of freedom, which usually thermalize in the range of several tens of picoseconds, that is, on time scales larger than the 5 ps period associated with the quantum density of states.
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Affiliation(s)
- Marc Joyeux
- Laboratoire de Spectrométrie Physique (CNRS UMR 5588), Université Joseph Fourier-Grenoble 1, Boîte Postale 87, 38402 St Martin d'Hères, France.
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Polianski M, Boyarkin OV, Rizzo TR. Collisionally assisted, highly selective laser isotope separation of carbon-13. J Chem Phys 2004; 121:11771-9. [PMID: 15634141 DOI: 10.1063/1.1822918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have further developed our recently reported two-laser technique for highly selective molecular isotope separation of carbon-13 [Boyarkin, Kowalczyk, and Rizzo, J. Chem. Phys. 118, 93 (2003)] with the objective of increasing the yield. An essential feature of this approach in its original conception is the significant increase of isotopic selectivity that occurs through collisions during the time between the overtone preexcitation laser pulse and the multiphoton dissociation pulse. We demonstrate here that under certain conditions, this collisional enhancement of the selectivity works equally well when the two pulses are overlapped in time, allowing the overall isotopic selectivity of the process to remain high while achieving a significant increase in the absolute dissociation yield. We also find that proper shaping of the CO2 laser dissociation pulse makes the fluence required for dissociation sufficiently low to allow irradiation of a large reaction volume by unfocused laser beams. Together, these factors may make this laser isotope separation scheme competitive with existing separation methods.
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Affiliation(s)
- M Polianski
- Laboratoire de chimie physique moléculaire, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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Letokhov VS, Ryabov EA. Laser Infrared Multiphoton Noncoherent Control of Intermolecular (Isotope) Selectivity for Polyatomic Molecules on a Practical Scale. Isr J Chem 2004. [DOI: 10.1560/m51m-j8eq-dexk-luvu] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Iung C, Gatti F, Meyer HD. Intramolecular vibrational energy redistribution in the highly excited fluoroform molecule: A quantum mechanical study using the multiconfiguration time-dependent Hartree algorithm. J Chem Phys 2004; 120:6992-8. [PMID: 15267599 DOI: 10.1063/1.1668639] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The present paper is devoted to a detailed study of the intramolecular vibrational energy redistribution in fluoroform initiated by a local mode excitation of the CH stretch [nnu(CH) (n=1,...,4)]. All nine internal degrees of freedom are explicitly taken into account and the full quantum mechanical simulation is performed by means of the multiconfiguration time-dependent Hartree algorithm. The existence of different time scales considerably complicates the dynamics. The mode-to-mode energy transfer is analyzed by calculating the evolution of the partial energies of all vibrational modes. This study emphasizes the crucial role played by the two-dimensional FCH bending modes which act as an energy reservoir. The fast energy flow into these bending modes significantly hinders an energy flow from the CH chromophore. Finally, our results are compared with those obtained previously with the wave operator sorting algorithm approach.
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Affiliation(s)
- Christophe Iung
- LSDSMS (UMR 5636), CC 014, Université Montpellier II 34095 Montpellier Cedex 05, France
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Polianski M, Boyarkin OV, Rizzo TR, Apatin VM, Laptev VB, Ryabov EA. Infrared Laser Chemistry of Trichlorosilane in View of Silicon Isotope Separation. J Phys Chem A 2003. [DOI: 10.1021/jp0356362] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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