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Blancafort-Jorquera M, Vilà A, González M. Rotational energy relaxation quantum dynamics of a diatomic molecule in a superfluid helium nanodroplet and study of the hydrogen isotopes case. Phys Chem Chem Phys 2019; 21:21007-21021. [PMID: 31528895 DOI: 10.1039/c9cp00952c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The rotational energy relaxation (RER) of a molecule X2(j,mj) in a 4He superfluid nanodroplet [HeND or (4He)N; T = 0.37 K] has been investigated using a hybrid quantum dynamics approach recently proposed by us. As far as we know, this is the first theoretical study about rotational relaxation inside HeNDs, and here several (real and hypothetical) isotopes of H2 have been examined, in order to analyze the influence of the rotational constant Be of these fast rotors on the dynamics. The structure of the nanodroplet practically does not change during the RER process, which approximately takes place according to a cascade mechanism j → j - 2; j - 2 → j - 4; …; 2 → 0, and mj is conserved. The results are consistent with the very scarce estimated experimental data available. The lifetime of an excited rotational state (≈1.0-7.6 ns) increases when: (a) Be increases; (b) j increases; and (c) N decreases (above N = 100 there is a small influence of N on the lifetime). This also applies to the global relaxation time and transition time. The analysis of the influence of the coupling between the j and j - 2 rotational states (due to the X2-helium interaction) and the X2 angular velocity on the lifetime and related properties has been helpful to better understand the dynamics. In contrast to the RER results, for the vibrational energy relaxation (VER) in HeNDs, when the quantum number v increases a decrease is observed in the lifetime of the excited vibrational state. This difference can be interpreted taking into account that RER and VER are associated with very different types of motion. Besides, in VER the intermediate excited states show metastability, differing from the RER case. We hope that the present study will encourage more studies to be developed on the RER dynamics in HeNDs, a basic, interesting and difficult to study physical phenomenon about which we still know very little.
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Affiliation(s)
- Miquel Blancafort-Jorquera
- Departament de Ciència de Materials i Química Física and IQTC, Universitat de Barcelona, Martí i Franquès, 1-11, 08028 Barcelona, Spain.
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Iwamoto Y, Tanimura Y. Open quantum dynamics of a three-dimensional rotor calculated using a rotationally invariant system-bath Hamiltonian: Linear and two-dimensional rotational spectra. J Chem Phys 2019; 151:044105. [DOI: 10.1063/1.5108609] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yuki Iwamoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yoshitaka Tanimura
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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Lin SR, Tang PH, Wu TM. Local structural effects on orientational relaxation of OH-bond in liquid water over short to intermediate timescales. J Chem Phys 2014; 141:214505. [PMID: 25481150 DOI: 10.1063/1.4902372] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
By simulating the rigid simple point charge extended model at temperature T = 300 K, the orientational relaxation of the OH-bond in water was investigated over short to intermediate timescales, within which molecules undergo inertial rotation and libration and then enter the rotational diffusion regime. According to the second-cumulant approximation, the orientational time correlation function (TCF) of each axis that is parallel or perpendicular to an OH-bond is related to an effective rotational density of states (DOS), which is determined using the power spectra of angular velocity autocorrelation functions (AVAFs) of the other two axes. In addition, the AVAF power spectrum of an axis was approximated as the rotational stable instantaneous normal mode (INM) spectrum of the axis. As described in a previous study [S. L. Chang, T. M. Wu, and C. Y. Mou, J. Chem. Phys. 121, 3605 (2004)], simulated molecules were classified into subensembles, according to either the local structures or the H-bond configurations of the molecules. For global molecules and the classified subensembles, the simulation results for the first- and second-rank orientational TCFs were compared with the second-cumulant predictions obtained using the effective rotational DOSs and the rotational stable-INM spectra. On short timescales, the OH-bond in water behaves similar to an inertial rotor and its anisotropy is lower than that of a water molecule. For molecules with three or more H-bonds, the OH-bond orientational TCFs are characterized by a recurrence, which is an indication for libration of the OH-bond. The recurrence can generally be described by the second-cumulant prediction obtained using the rotational stable-INM spectra; however, the orientational TCFs after the recurrence switch to a behavior similar to that predicted using the AVAF power spectra. By contrast, the OH-bond orientational TCFs of molecules initially connected with one or two H-bonds decay monotonically or exhibit a weak recurrence, indicating rapid relaxation into the rotational diffusion regime after the initial Gaussian decay. In addition to accurately describing the Gaussian decay, the second-cumulant predictions formulated using the rotational stable-INM spectra and the AVAF power spectra serve as the upper and lower limits, respectively, for the OH-bond orientational TCFs of these molecules after the Gaussian decay.
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Affiliation(s)
- S R Lin
- Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan
| | - Ping-Han Tang
- Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan
| | - Ten-Ming Wu
- Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan
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Peng J, Castonguay TC, Coker DF, Ziegler LD. Ultrafast H[sub 2] and D[sub 2] rotational Raman responses in near critical CO[sub 2]: An experimental and theoretical study of anisotropic solvation dynamics. J Chem Phys 2009; 131:054501. [DOI: 10.1063/1.3186732] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Savitzky BH, Stratt RM. Anatomy of an Energy Transfer Event in a Liquid: The High-Energy Rotational Relaxation of OH in Solution. J Phys Chem B 2008; 112:13326-34. [DOI: 10.1021/jp805792e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Richard M. Stratt
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
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Tao G, Stratt RM. Anomalously Slow Solvent Structural Relaxation Accompanying High-Energy Rotational Relaxation. J Phys Chem B 2007; 112:369-77. [DOI: 10.1021/jp075664a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Guohua Tao
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
| | - Richard M. Stratt
- Department of Chemistry, Brown University, Providence, Rhode Island 02912
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Navrotskaya I, Geva E. Vibrational Energy Relaxation Rates of H2 and D2 in Liquid Argon via the Linearized Semiclassical Method. J Phys Chem A 2006; 111:460-7. [PMID: 17228894 DOI: 10.1021/jp066243g] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The vibrational energy relaxation (VER) rates for H2 and D2 in liquid argon (T=152 K, rho=1.45x1022 cm-3) are calculated using the linearized semiclassical (LSC) method (J. Phys. Chem. 2003, 107, 9059, 9070). The calculation is based on Fermi's golden rule. The VER rate constant is expressed in terms of the quantum-mechanical force-force correlation function, which is then estimated using the LSC method. A local harmonic approximation (LHA) is employed in order to compute the multidimensional Wigner integrals underlying the LSC approximation. The H2-Ar and D2-Ar interactions are described by the three-body potential of Bissonette et al. (J. Phys. Chem. A 1996, 105, 2639). The LHA-LSC-based VER rate constants for both D2 and H2 are found to be about 2-3 orders of magnitude slower than those obtained experimentally. However, their ratio agrees quantitatively with the corresponding experimental result. In contrast, the classical VER rate constants are found to be 8-9 orders of magnitude slower than those obtained experimentally, and their ratio is found to be qualitatively different from the corresponding experimental result.
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Affiliation(s)
- Irina Navrotskaya
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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Tao G, Stratt RM. The molecular origins of nonlinear response in solute energy relaxation: The example of high-energy rotational relaxation. J Chem Phys 2006; 125:114501. [PMID: 16999484 DOI: 10.1063/1.2336780] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A key step in solution-phase chemical reactions is often the removal of excess internal energy from the product. Yet, the way one typically studies this process is to follow the relaxation of a solute that has been excited into some distribution of excited states quite different from that produced by any reaction of interest. That the effects of these different excitations can frequently be ignored is a consequence of the near universality of linear-response behavior, the idea that relaxation dynamics is determined by the solvent fluctuations (which may not be all that different for different kinds of solute excitation). Nonetheless, there are some clear examples of linear-response breakdowns seen in solute relaxation, including a recent theoretical and experimental study of rapidly rotating diatomics in liquids. In this paper we use this rotational relaxation example to carry out a theoretical exploration of the conditions that lead to linear-response failure. Some features common to all of the linear-response breakdowns studied to date, including our example, are that the initial solute preparation is far from equilibrium, that the subsequent relaxation promotes a significant rearrangement of the liquid structure, and that the nonequilibrium response is nonstationary. However, we show that none of these phenomena is enough to guarantee a nonlinear response. One also needs a sufficient separation between the solute time scale and that of the solvent geometry evolution. We illustrate these points by demonstrating precisely how our relaxation rate is tied to our liquid-structural evolution, how we can quantitatively account for the initial nonstationarity of our effective rotational friction, and how one can tune our rotational relaxation into and out of linear response.
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Affiliation(s)
- Guohua Tao
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
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Ramakrishna S, Seideman T. Dissipative dynamics of laser induced nonadiabatic molecular alignment. J Chem Phys 2006; 124:034101. [PMID: 16438561 DOI: 10.1063/1.2130708] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Nonadiabatic alignment induced by short, moderately intense laser pulses in molecules coupled to dissipative environments is studied within a nonperturbative density matrix theory. We focus primarily on exploring and extending a recently proposed approach [Phys. Rev. Lett. 95, 113001 (2005)], wherein nonadiabatic laser alignment is used as a coherence spectroscopy that probes the dissipative properties of the solvent. To that end we apply the method to several molecular collision systems that exhibit sufficiently varied behavior to represent a broad variety of chemical environments. These include molecules in low temperature gas jets, in room temperature gas cells, and in dense liquids. We examine also the possibility of prolonging the duration of the field free (post-pulse) alignment in dissipative media by a proper choice of the system parameters.
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Affiliation(s)
- S Ramakrishna
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
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Ramakrishna S, Seideman T. Intense laser alignment in dissipative media as a route to solvent dynamics. PHYSICAL REVIEW LETTERS 2005; 95:113001. [PMID: 16196999 DOI: 10.1103/physrevlett.95.113001] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Indexed: 05/04/2023]
Abstract
We extend the concept of alignment by short intense pulses to dissipative environments within a density matrix formalism and illustrate the application of this method as a probe of the dissipative properties of dense media. In particular, we propose a means of disentangling rotational population relaxation from decoherence effects via strong laser alignment. We illustrate also the possibility of suppressing rotational relaxation to prolong the alignment lifetime through choice of the field parameters. Implications to several disciplines and a number of potential applications are proposed.
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Affiliation(s)
- S Ramakrishna
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
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Wu TM, Chang SL, Tsai KH. Mechanism for singular behavior in vibrational spectra of topologically disordered systems: short-range attractions. J Chem Phys 2005; 122:204501. [PMID: 15945746 DOI: 10.1063/1.1900726] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
At low-enough fluid densities, we have found some naive singular behavior, like the van Hove singularities in the phonon spectra of lattices, appearing in the instantaneous normal mode spectra of the Lennard-Jones (LJ) 2n-n fluids, which serve as a prototype of topologically disordered systems. The singular behavior cannot be predicted by the mean-field theory, but interpreted by the perturbed binary modes of some special pairs, called the mutual nearest neighbor pairs, at separations corresponding to the extreme binary frequencies, which are solely determined by the attractive part of the LJ 2n-n pair potential. By reducing the range of attraction in the pair potential under the conditions of the same particle diameter and well depth, the tendency for the appearance of the singular behavior shifts to higher fluid densities. From this study, we conclude that pair potential with a short-range attraction can be a mechanism to produce a counterpart of the van Hove singularity in the vibrational spectra of disordered systems without a reference lattice.
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Affiliation(s)
- Ten-Ming Wu
- Institute of Physics, National Chiao-Tung University, Hsin chu, Taiwan, Republic of China.
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Mikami T, Okazaki S. An analysis of molecular origin of vibrational energy transfer from solute to solvent based upon path integral influence functional theory. J Chem Phys 2003. [DOI: 10.1063/1.1595643] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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Moskun AC, Bradforth SE. Photodissociation of ICN in polar solvents: Evidence for long lived rotational excitation in room temperature liquids. J Chem Phys 2003. [DOI: 10.1063/1.1591726] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Deng Y, Ladanyi BM, Stratt RM. High-frequency vibrational energy relaxation in liquids: The foundations of instantaneous-pair theory and some generalizations. J Chem Phys 2002. [DOI: 10.1063/1.1517300] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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Padilla A, Pérez J, Calvo Hernández A. Rotational energy relaxation of polar diatomic molecules diluted in simple liquids. J Chem Phys 2002. [DOI: 10.1063/1.1505864] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Deng Y, Stratt RM. Vibrational energy relaxation of polyatomic molecules in liquids: The solvent’s perspective. J Chem Phys 2002. [DOI: 10.1063/1.1489417] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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Ma A, Stratt RM. The molecular origins of the two-dimensional Raman spectrum of an atomic liquid. II. Instantaneous-normal-mode theory. J Chem Phys 2002. [DOI: 10.1063/1.1453402] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Kwon Y, Huang P, Patel MV, Blume D, Whaley KB. Quantum solvation and molecular rotations in superfluid helium clusters. J Chem Phys 2000. [DOI: 10.1063/1.1310608] [Citation(s) in RCA: 218] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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