Low-frequency isotropic and anisotropic Raman spectra of aromatic liquids

Heisler, Ismael A.; Meech, Stephen R.

doi:10.1063/1.3408288

Cited by 17 publications

(31 citation statements)

References 48 publications

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“…Surely, the time or frequency (not amplitude) for the translational motion caused by the interaction-induced motion including collision-induced motion depends on the mass. 93 The present result also shows this trace: the characteristic frequency of the lowest component in the differential spectra for AI/CCl 4 is lower than that for BF/CCl 4 (ω O1 in Tables I and II). Accordingly, the present result of the low frequency region in the differential spectra for AI/CCl 4 and BF/CCl 4 can be attributed to the difference in molecular weight: dimer in the case of AI and monomer in the case of BF.…”

Section: A Intermolecular Vibrational Modes and Spectrasupporting

confidence: 49%

Intermolecular vibrational modes and orientational dynamics of cooperative hydrogen-bonding dimer of 7-azaindole in solution

Kato

Shirota

2011

The Journal of Chemical Physics

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We observed the low-frequency Raman-active intermolecular vibrational modes of 7-azaindole in CCl(4) by femtosecond Raman-induced Kerr effect spectroscopy. To understand the dynamical aspects and vibrational modes of 7-azaindole in the solution, the ultrafast dynamics of 1-benzofuran in CCl(4) was also examined as a reference and ab initio quantum chemistry calculations were performed for 7-azaindole and 1-benzofuran. The cooperative hydrogen-bonding vibrational bands of 7-azaindole dimer in CCl(4) appeared at 89 cm(-1) and 105 cm(-1) represent the overlap of stagger and wheeling modes and the intermolecular stretching mode, respectively. They are almost independent of the concentration in the solution. We further found from the low-frequency differential Kerr spectra of the solutions with neat CCl(4) that the intermolecular motion in the low frequency region below 20 cm(-1) was less active in the case of 7-azaindole/CCl(4) than in the case of 1-benzofuran/CCl(4). The slow orientational relaxation time in 7-azaindole/CCl(4) is ~3.5 times that in 1-benzofuran/CCl(4) because of the nature of the dimerization of 7-azaindole.

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Section: A Intermolecular Vibrational Modes and Spectrasupporting

confidence: 49%

Intermolecular vibrational modes and orientational dynamics of cooperative hydrogen-bonding dimer of 7-azaindole in solution

Kato

Shirota

2011

The Journal of Chemical Physics

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“…The low-frequency Raman spectrum of benzene has been studied extensively in both the time and frequency domains through experiments 8,9,[13][14][15][16][17][18][19][20][21][22][23][24] and molecular simulations. 11,18,[25][26][27][28] McMorrow and Lotshaw observed the broad, flattened shape of the benzene OKE spectrum in 1993, and on a preliminary basis concluded that the spectral features are a result of collective modes arising from molecular aggregates.…”

Section: Introductionmentioning

confidence: 99%

Assessing Polarizability Models for the Simulation of Low-Frequency Raman Spectra of Benzene

2014

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Optical Kerr effect (OKE) spectroscopy is a widely used technique for probing the low-frequency, Raman-active dynamics of liquids. Although molecular simulations are an attractive tool for assigning liquid degrees of freedom to OKE spectra, the accurate modeling of the OKE and the motions that contribute to it relies on the use of a realistic and computationally tractable molecular polarizability model. Here we explore how the OKE spectrum of liquid benzene, and the underlying dynamics that determines its shape, are affected by the polarizability model employed. We test a molecular polarizability model that uses a point anisotropic molecular polarizability and three other models that distribute the polarizability over the molecule. The simplest and most computationally efficient distributed polarizability model tested is found to be sufficient for the accurate simulation of the many-body polarizability dynamics of this liquid. We further find that the atomic-to-molecular polarizability transformation approximation [Hu et al. J. Phys. Chem. B 2008, 112, 7837-7849], used in conjunction with this distributed polarizability model, yields OKE spectra whose shapes differ negligibly from those calculated without this approximation, providing a substantial increase in computational efficiency.

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“…Non-resonant 4-wave-mixing experiments 1 such as optical-Kerr 2-5 and transientgrating 6 spectra are attractive in that they are light-scattering probes that monitor the many-body polarizability of entire liquid-which means that they report on the collective dynamics of the liquid as a whole. [7][8][9] But while there has been considerable progress made in arriving at molecular interpretations of optical Kerr spectra, 3,[10][11][12][13][14][15][16][17][18][19][20][21][22] their non-resonant character also means that they have only a limited degree of specificity as to which molecules and which length scales they are seeing. Experiments such as time-dependent fluorescence, transient absorption, transient anisotropy, and photon echoes, on the other hand, are resonant studies of the electronic transitions of some solute.…”

Section: Introductionmentioning

confidence: 99%

The molecular underpinnings of a solute-pump/solvent-probe spectroscopy: the theory of polarizability response spectra and an application to preferential solvation

Sun

Stratt

2012

Phys. Chem. Chem. Phys.

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Recent ultrafast experiments on liquids have made clear that it is possible to go beyond light scattering techniques such as optical Kerr spectroscopy that look at the dynamics of a liquid as a whole. It is now possible to measure something far more conceptually manageable: how that liquid dynamics (and that light scattering) can be modified by electronically exciting a solute. Resonant-pump polarizability-response spectra (RP-PORS) in particular, seem to show that different solvents respond in noticeably distinct ways to such solute perturbations. This paper is a theoretical attempt at understanding the kinds of molecular information that can be revealed by experiments of this sort. After developing the general classical statistical mechanical linear response theory for these spectra, we show that the experimentally interesting limit of long solute-pump/solvent-probe delays corresponds to measuring the differences in 4-wave-mixing spectra between solutions with equilibrated ground- and excited-state solutes-meaning that the spectra are essentially probes of how changing liquid structure affects intermolecular liquid vibrations and librations. We examine the spectra in this limit for the special case of an atomic solute dissolved in an atomic-liquid mixture, a preferential solvation problem, and show that, as with the experimental spectra, different solvents can lead to spectra with different magnitudes and even different signs. Our molecular-level analysis of these results points out that solvents can also differ in how local a portion of the solvent dynamics is accessed by this spectroscopy.

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Low-frequency isotropic and anisotropic Raman spectra of aromatic liquids

Cited by 17 publications

References 48 publications

Intermolecular vibrational modes and orientational dynamics of cooperative hydrogen-bonding dimer of 7-azaindole in solution

Intermolecular vibrational modes and orientational dynamics of cooperative hydrogen-bonding dimer of 7-azaindole in solution

Assessing Polarizability Models for the Simulation of Low-Frequency Raman Spectra of Benzene

The molecular underpinnings of a solute-pump/solvent-probe spectroscopy: the theory of polarizability response spectra and an application to preferential solvation

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