Heterogeneity length scale for oxygen diffusion in glassy squalane

Abstract The kinetics of phenanthrene phosphorescence quenching by mobile oxygen molecules was used to study characteristics of oxygen diffusion on a nanometer length scale in glassy squalane. The phosphorescence decay was described using a model of glassy matrix with spatially correlated oxygen jump rates. The correlation length was determined to be 2.5 nm. The dispersion of barrier energy for oxygen jumps is 1.8 kJ/mol and the average barrier energy is 32 kJ/mol. The structural heterogeneities are deduced to be fluctuations in structure frozen in from the supercooled liquid.