Microscopic dynamics in simple liquids: a clue to understanding the basic thermodynamics of the liquid state

Cabrillo, C.; Bermejo, F. J.; Maira-Vidal, A.; Fernández-Perea, Ricardo; Bennington, S. M.; Martin, D.G.

doi:10.1088/0953-8984/16/5/001

Cited by 19 publications

(5 citation statements)

References 54 publications

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“…This is known to be the case for molten simple alkali metals such as K, 21 but goes counter to what is found for complex liquids such as Ga. 22 The wave-vector dependence of the parameters obtained after fitting the experimental results with Eq. ͑3͒, and ⌫, is shown in Fig.…”

Section: 15mentioning

confidence: 76%

High-frequency collective excitations in molten and glassy Te studied by inelastic neutron scattering

Ruiz-Martín¹,

Jiménez‐Ruiz²,

Bermejo³

et al. 2006

Phys. Rev. B

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The spectra of collective excitations of liquid and glassy tellurium have been studied by means of inelastic neutron scattering. Here we report on the dynamics of liquid Te as measured at two different temperatures, just above melting ͑T m = 723 K͒ and at ϳ1000 K as well as the glass that is studied at room temperature. Estimates for the velocity of propagating excitations for both temperatures have been obtained from the experimental data, and a contrasting behavior is found with respect to anomalies shown by the adiabatic sound velocity measured by ultrasound methods. The origin of such differences is finally discussed.

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Section: 15mentioning

confidence: 76%

High-frequency collective excitations in molten and glassy Te studied by inelastic neutron scattering

Ruiz-Martín¹,

Jiménez‐Ruiz²,

Bermejo³

et al. 2006

Phys. Rev. B

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“…13 There, it was found that the slope of the Q phonon frequencies for wave vectors below Ϸ0.7 Å −1 , where the dispersion relation is almost linear, increases by some 11.6% while the increase due to density is obviously far more modest. From data on classical liquids such as molten metals 26 we know that such phonon frequencies are generally close to those followed by the fourth moment of the response function…”

Section: A Density Dependence Of the Kinetic Energymentioning

confidence: 82%

Density dependence of the momentum distributions in liquidpara-hydrogen

et al. 2006

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Momentum distributions of liquid para-hydrogen were determined by means of inelastic neutron scattering under applied pressures ranging from 1 to 80 bars, at T = 16.5 K. The data processing procedure involves the parametrization of the dynamic structure factor and yields a set of momentum distributions as functions of the density. The results depict significant pressure dependences for all single-particle quantities such as the momentum distributions and average kinetic energies as well as for the final-state effects. The obtained results enable us to quantify the departure of the momentum distributions from classical Maxwell-Gauss shape. Such observations are then rationalized with the help of calculations that were carried out in terms of the correlated density matrix formalism.

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“…It has been shown by neutron or inelastic x-ray scattering (IXS) spectroscopy that the vibrations in the boson peak range have a partial character of transverse acoustic modes of high wavevectors that are hybridized with localized vibrations due to the disorder of the amorphous phase. 35,[48][49][50][51][52][53] In the authors knowledge, collective dynamics of ionic liquids has not yet been investigated by IXS spectroscopy. On the other hand, molecular dynamics (MD) simulations have played a crucial role to unravel the mixed nature of sound-like and localized modes within the range 1 < ω < 100 cm −1 .…”

Section: Discussionmentioning

confidence: 99%

Pressure and temperature effects on intermolecular vibrational dynamics of ionic liquids

Penna

Faria

Matos

et al. 2013

The Journal of Chemical Physics

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Low frequency Raman spectra of ionic liquids have been obtained as a function of pressure up to ca. 4.0 GPa at room temperature and as a function of temperature along the supercooled liquid and glassy state at atmospheric pressure. Intermolecular vibrations are observed at ~20, ~70, and ~100 cm(-1) at room temperature in ionic liquids based on 1-alkyl-3-methylimidazolium cations. The component at ~100 cm(-1) is assigned to librational motion of the imidazolium ring because it is absent in non-aromatic ionic liquids. There is a correspondence between the position of intermolecular vibrational modes in the normal liquid state and the spectral features that the Raman spectra exhibit after partial crystallization of samples at low temperatures or high pressures. The pressure-induced frequency shift of the librational mode is larger than the other two components that exhibit similar frequency shifts. The lowest frequency vibration observed in a glassy state corresponds to the boson peak observed in light and neutron scattering spectra of glass-formers. The frequency of the boson peak is not dependent on the length scale of polar∕non-polar heterogeneity of ionic liquids, it depends instead on the strength of anion-cation interaction. As long as the boson peak is assigned to a mixing between localized modes and transverse acoustic excitations of high wavevectors, it is proposed that the other component observed in Raman spectra of ionic liquids has a partial character of longitudinal acoustic excitations.

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Microscopic dynamics in simple liquids: a clue to understanding the basic thermodynamics of the liquid state

Cited by 19 publications

References 54 publications

High-frequency collective excitations in molten and glassy Te studied by inelastic neutron scattering

High-frequency collective excitations in molten and glassy Te studied by inelastic neutron scattering

Density dependence of the momentum distributions in liquidpara-hydrogen

Pressure and temperature effects on intermolecular vibrational dynamics of ionic liquids

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