Orientational dynamics on glassformer 2 [Ca(NO3)2] · 3[KNO3]: A study by transient optical Kerr effect

Year: 1993

Authors: Ricci M., Foggi P., Righini R., Torre R.

Autors Affiliation: LENS (European Laboratory for Non-linear Spectroscopy), Largo E. Fermi, 2-50125 Firenze, Italy; Department of Chemistry, Universita\’ di Firenze, via Gino Capponi, 9-50121 Firenze, Italy

Abstract: The fast orientational dynamics of molten 2[Ca(NO3)2] · 3[KNO3] is investigated by time-resolved optical Kerr effect (OKE) with subpicosecond resolution in the temperature range 380-620 K. Apart from the instantaneous electronic response and a very fast decay, the OKE intensity profiles show clearly the presence of a nonexponential decay. The simplest function which fits the experimental data is a biexponential with time constants ranging from 120 to 15 and 10 to 3 ps, respectively. The results are discussed in terms of an integrated correlation time tc that does not show a diverging behavior approaching the glass transition. At high temperatures tc follows a typical Arrhenius law with activation energy of 1.5 kcal/M. Different possible interpretations of the observed behavior (a-ß bifurcation, domain size effect) are discussed. The main conclusion is that rotational motions are decoupled from translational ones even for temperatures well above the liquid-glass transition.

Journal/Review: JOURNAL OF CHEMICAL PHYSICS

Volume: 98 (6)      Pages from: 4892  to: 4896

KeyWords: Liquid-glass-transition; Structural relaxation
DOI: 10.1063/1.464944

Citations: 16
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