Physical Sciences and Mathematics Commons^™

Appearance Of A Fractional Stokes-Einstein Relation In Water And A Structural Interpretation Of Its Onset, L. Xu, F. Mallamace, Z. Yan, Francis W. Starr, S. V. Buldyrev, H. E. Stanley

Francis Starr

The Stokes–Einstein relation has long been regarded as one of the hallmarks of transport in liquids. It predicts that the self-diffusion constant D is proportional to (τ/T)−1, where τ is the structural relaxation time and T is the temperature. Here, we present experimental data on water confirming that, below a crossover temperature T× ≈ 290 K, the Stokes– Einstein relation is replaced by a ‘fractional’ Stokes–Einstein relation D ∼ (τ/T)−ζ with ζ ≈ 3/5 (refs 1–6). We interpret the microscopic origin of this crossover by analysing the OH- stretch region of the Fourier transform infrared spectrum over a temperature range …