Measuring self-diffusion in super-cooled liquid droplets with pulsed gradient spin echo (PGSE) techniques

Abstract

Measurement of the self-diffusion of constituent materials in highly super-cooled liquids mixtures was achieved using a simple droplet suspension technique combined with pulsed field gradient (PFG) nuclear magnetic resonance (NMR). The self-diffusion coefficients of both water and sucrose were determined over a range of concentrations from 10–50% (w/w) sucrose, and for temperatures down to −20 °C. The resultant self-diffusion data were in reasonably good agreement with the Vogel–Tamman–Fulcher (VTF) equation for both water and sucrose. The suspended droplets were subsequently frozen and the self-diffusion data for water used to estimate the concentration of the unfrozen fraction of the droplets.