Viscosity Dependence of Diffusion-controlled Triplet Energy Transfer in 2-Methylpentan 2-,4-diol

Abstract

The rate constant for triplet energy transfer from phenanthrene to stilbene has been studied in 2-methylpentan 2-,4-diol over the temperature range 190–350 K. It shows a non-Arrhenius dependence which can be described by the VTF equation k=AT exp {–B/(T–T0)}, where B=(850 ± 100) K and T0= 158 K. The B-value is smaller than that derived from viscosity data. Similar results are obtained from less extensive investigations of naphthalene + chromium acetyl-acetonate and anthracene + perylene. The data for phenanthrene + stilbene, which cover nine decades in rate constant, are inadequately described by the empirical equation (kη/T)=a+bηx, where a, b and x are constants.