We studied the relaxation processes of glycerol by a transient grating experiment with polarization selectivity and optical heterodyne detection. The density response of supercooled glycerol, for a wavevector q = 0.63 mum(-1), has been studied in that temperature range (T = 200-340 K), where the rearrangement of the structure (alpha-relaxation) and thermal diffusion occur on the same timescale. A strong interaction between the two modes is observed, manifesting in a dip in the T dependence of the apparent thermal conductivity and in a flattening of the apparent alpha-relaxation time upon cooling. A parameter-free thermohydrodynamic model for the long-time response is developed. The model is capable of quantitatively reproducing the data and of explaining the observed phenomenology.
Structural and entropic modes in supercooled liquids: an experimental and theoretical study / R.DI LEONARDO; A.TASCHIN; R. TORRE; M.SAMPOLI; G.RUOCCO. - In: JOURNAL OF PHYSICS. CONDENSED MATTER. - ISSN 0953-8984. - STAMPA. - 15:(2003), pp. S1181(1)-S1181(5).
Structural and entropic modes in supercooled liquids: an experimental and theoretical study
TASCHIN, ANDREA;TORRE, RENATO;SAMPOLI, MARCO;
2003
Abstract
We studied the relaxation processes of glycerol by a transient grating experiment with polarization selectivity and optical heterodyne detection. The density response of supercooled glycerol, for a wavevector q = 0.63 mum(-1), has been studied in that temperature range (T = 200-340 K), where the rearrangement of the structure (alpha-relaxation) and thermal diffusion occur on the same timescale. A strong interaction between the two modes is observed, manifesting in a dip in the T dependence of the apparent thermal conductivity and in a flattening of the apparent alpha-relaxation time upon cooling. A parameter-free thermohydrodynamic model for the long-time response is developed. The model is capable of quantitatively reproducing the data and of explaining the observed phenomenology.File | Dimensione | Formato | |
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