Brasil | Artículos de revistas
dc.creatorRIBEIRO, Mauro C. C.
dc.date.accessioned2012-04-19T15:57:04Z
dc.date.accessioned2018-07-04T14:43:47Z
dc.date.available2012-04-19T15:57:04Z
dc.date.available2018-07-04T14:43:47Z
dc.date.created2012-04-19T15:57:04Z
dc.date.issued2011
dc.identifierJOURNAL OF CHEMICAL PHYSICS, v.134, n.24, 2011
dc.identifier0021-9606
dc.identifierhttp://producao.usp.br/handle/BDPI/16816
dc.identifier10.1063/1.3604533
dc.identifierhttp://dx.doi.org/10.1063/1.3604533
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1613637
dc.description.abstractShort-time dynamics of ionic liquids has been investigated by low-frequency Raman spectroscopy (4 < omega < 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 (similar to 19 angstrom) 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. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3604533]
dc.languageeng
dc.publisherAMER INST PHYSICS
dc.relationJournal of Chemical Physics
dc.rightsCopyright AMER INST PHYSICS
dc.rightsopenAccess
dc.subjectboson systems
dc.subjectentropy
dc.subjectlibrational states
dc.subjectneutron diffraction
dc.subjectoptical Kerr effect
dc.subjectorganic compounds
dc.subjectquasi-elastic scattering
dc.subjectRaman spectra
dc.subjectrotational-vibrational energy transfer
dc.subjectsupercooling
dc.subjectvitrification
dc.subjectX-ray scattering
dc.titleIntermolecular vibrations and fast relaxations in supercooled ionic liquids
dc.typeArtículos de revistas


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