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Microscopic dynamics and relaxation processes in liquid Hydrogen Fluoride

R. Angelini·P. Giura·D. Fioretto·G. Monaco·G. Ruocco·F. Sette
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Abstract

Inelastic x-ray scattering and Brillouin light scattering measurements of the dynamic structure factor of liquid hydrogen fluoride have been performed in the temperature range$ T=214÷283 K$. The data, analysed using a viscoelastic model with a two timescale memory function, show a positive dispersion of the sound velocity $c(Q)$ between the low frequency value $c_0(Q)$ and the high frequency value $c_{\infty α}(Q)$. This finding confirms the existence of a structural ($α$) relaxation directly related to the dynamical organization of the hydrogen bonds network of the system. The activation energy $E_a$ of the process has been extracted by the analysis of the temperature behavior of the relaxation time $τ_α(T)$ that follows an Arrhenius law. The obtained value for $E_a$, when compared with that observed in another hydrogen bond liquid as water, suggests that the main parameter governing the $α$-relaxation process is the number of the hydrogen bonds per molecule.

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R. Angelini, P. Giura, D. Fioretto, G. Monaco, G. Ruocco, F. Sette. 2004-03-16. Microscopic dynamics and relaxation processes in liquid Hydrogen Fluoride. https://doi.org/10.1103/physrevb.70.224302

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