Structure of the Rayleigh line wing in highly viscous Iiquids

Gochiyaev, V. Z.; Malinovsky, V. K.; Novikov, V. N.; Sokolov, Alexei P.

doi:10.1080/13642819108225986

Cited by 103 publications

(62 citation statements)

References 16 publications

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“…3. The spectrum of the liquid C 6 OH is characterized by the strong scattering structureless line (a wing of the Rayleigh line) reaching its maximum at zero-shift frequency 47 (curve a). Upon cooling, a transition to the OD phase I occurs at 296 K. The curve b in Fig.…”

Section: A Orientational Glass and Orientationally Disordered Phasementioning

confidence: 99%

Effects of internal molecular degrees of freedom on the thermal conductivity of some glasses and disordered crystals

et al. 2012

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The thermal conductivity κ(T ) of the fully ordered stable phase II, the metastable phase III, the orientationally disordered (plastic) phase I, as well as the nonergodic orientational glass (OG) phase, of the glass former cyclohexanol (C 6 H 11 OH) has been measured under equilibrium vapor pressure within the 2-200 K temperature range. The main emphasis is here focused on the influence of the conformational disorder upon the thermal properties of this material. Comparison of results with those regarding cyanoclyclohexane (C 6 H 11 CN), a chemically related compound, serves to quantify the role played by the terminal groups -OH and -CN on the phonon scattering processes. The picture that emerges shows that motions of such groups do play a minor role as scattering centers, both within the low-temperature orientationally ordered phases as well as in the OG states. The results are analyzed within the Debye-Peierls relaxation time model for isotropic solids comprising mechanisms for long-wave phonon scattering within the OG and orientational ordered low-temperature phases, as well as others arising from localized short-wavelength vibrational modes as pictured by the Cahill-Pohl model. By means of complementary neutron and Raman scattering we show that in the OG state the energy landscapes for both compounds are very similar.

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Section: A Orientational Glass and Orientationally Disordered Phasementioning

confidence: 99%

Effects of internal molecular degrees of freedom on the thermal conductivity of some glasses and disordered crystals

et al. 2012

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“…41,85 In low-frequency Raman spectroscopy, it is known that the temperature dependence of the QES intensity, I QES , in the supercooled liquid range is steeper than below T g . [27][28][29][30][31][32][33][34][57][58][59][60] The change of slope of the I QES (T) curve at T g is at first sight a remarkable finding, since QES is related to processes taking place at picosecond time scale while the glass transition is due to the structural α-relaxation time, τ α , reaching 10 2 -10 3 s. In fact, the relationship between I QES and α-relaxation is another example of these correlations between fast and slow dynamics of glassforming liquids.…”

Section: Fragility Of Glass-forming Liquids M = Dln[η(t)]/d(t G /T) mentioning

confidence: 98%

“…[57][58][59][60] It has been already shown that both the models give good fit to 31 but these models need assumptions concerning the functions to be used in fits. Thus, we follow here instead a less model dependent procedure, and we considered I QES as the integral up to the boson peak, say 4 < ω < 20 cm −1 , of the experimental spectrum normalized by intensity of high frequency bands.…”

Section: Fragility Of Glass-forming Liquids M = Dln[η(t)]/d(t G /T) mentioning

confidence: 99%

“…Such correlation strengths the proposition of an indirect mechanism for the QES contribution, 56 for instance, as in the coupling model, in which the QES intensity increases with temperature due to damping of the boson peak vibrations. 34,55,[57][58][59] Rather than a superposition model of two independent functions for QES and boson peak, the Raman spectrum is calculated in the coupling model by averaging a purely vibrational contribution, usually assumed as the Raman spectrum recorded at very low temperature, with a function giving the relaxations from all of the processes damping the vibrations. Both the superposition and the coupling models can give good fit to experimental spectra, for instance, see the studies of the glassformer GeSBr 2 31 Therefore, the coupling model is favored on the basis of arguments as mentioned above, but not just from better agreement to experiment.…”

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Intermolecular vibrations and fast relaxations in supercooled ionic liquids

Ribeiro

2011

The Journal of Chemical Physics

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Time-averaging approximation in the interaction picture: Absorption line shapes for coupled chromophores with application to liquid water J. Chem. Phys. 135, 154114 (2011) Response to "Comment on 'Isotope effects in liquid water by infrared spectroscopy. IV. No free OH groups in liquid water'" [J. Chem. Phys. 135, 117101 (2011)] J. Chem. Phys. 135, 117102 (2011) Ab initio investigation on ion-associated species and association process in aqueous Na2SO4 and Na2SO4/MgSO4 solutions J. Chem. Phys. 135, 084309 (2011) Ultrafast 2D IR anisotropy of water reveals reorientation during hydrogen-bond switching J. Chem. Phys. 135, 054509 (2011) Isotope effects in liquid water by infrared spectroscopy. V. A sea of OH4 of C2v symmetry J. Chem. Phys. 134, 164502 (2011) Additional information on J. Chem. Phys. Short-time dynamics of ionic liquids has been investigated by low-frequency Raman spectroscopy (4 < ω < 100 cm −1 ) within the supercooled liquid range. Raman spectra are reported for ionic liquids with the same anion, bis(trifluoromethylsulfonyl)imide, and different cations: 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-butyl-1-methylpiperidinium, trimethylbutylammonium, and tributylmethylammonium. It is shown that low-frequency Raman spectroscopy provides similar results as optical Kerr effect (OKE) spectroscopy, which has been used to study intermolecular vibrations in ionic liquids. The comparison of ionic liquids containing aromatic and non-aromatic cations identifies the characteristic feature in Raman spectra usually assigned to librational motion of the imidazolium ring. The strength of the fast relaxations (quasi-elastic scattering, QES) and the intermolecular vibrational contribution (boson peak) of ionic liquids with non-aromatic cations are significantly lower than imidazolium ionic liquids. A correlation length assigned to the boson peak vibrations was estimated from the frequency of the maximum of the boson peak and experimental data of sound velocity. The correlation length related to the boson peak (∼19 Å) does not change with the length of the alkyl chain in imidazolium cations, in contrast to the position of the first-sharp diffraction peak observed in neutron and X-ray scattering measurements of ionic liquids. The rate of change of the QES intensity in the supercooled liquid range is compared with data of excess entropy, free volume, and mean-squared displacement recently reported for ionic liquids. The temperature dependence of the QES intensity in ionic liquids illustrates relationships between short-time dynamics and long-time structural relaxation that have been proposed for glass-forming liquids.

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“…Исследование эволюции низкочастотных спектров КРС стекол в зависимости от изменений температуры в интервале от T < T g до T ~ T m (T g и Т m -температуры стеклования и плавления соот ветственно) позволили нам получить информацию о релаксационных свойствах материала и переходе стекло-жидкость. В [16 ] Присутствие бозонного пика в спектрах переох лажденной жидкости, обнаруженное в [16], свиде тельствует о том, что кластеры сохраняются также и в жидком состоянии, вплоть до T m , по крайней мере на временах порядка времени жизни квазилокаль ных колебательных возбуждений, ответственных за бозонный пик, т.е.…”

Section: у с п е х и ф и з и ч е с к и х н а у кunclassified