Diffusion of dioxygen in n-alkanes

The translational diffusion constant, D, of dioxygen, O-2, has been measured in n-alkane solutions drawn through a microcapillary by reduced pressure. The passage of O-2 through the capillary has been monitored using its UV absorption at 190 nm. Data were taken in hexane, octane, decane, dodecane, tetradecane, and hexadecane. The diffusion constants decrease as the chain length increases and are not in agreement with the Stokes-Einstein relation. The data can be fitted to D/T = A/eta(p) with A = 1.27 x 10(-8) and p = 0.562 (p = 1 for the Stokes-Einstein relation); T is the absolute temperature, and eta is the viscosity in P.