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+bη^x, where a, b and x are constants.