THE MEASUREMENT OF AN ELECTRON-TRANSFER REACTION IN A NONPOLAR SUPERCRITICAL-FLUID

The intermolecular electron transfer reaction between a biphenyl anion and pyrene in supercritical ethane was studied using pulse radiolysis . Second-order electron transfer rates were found to be of the order o f 10(11) M(-1) s(-1). The rate constants appear to be approximately co nstant over the pressure range 55-133 bar. Two possibilities are discu ssed that could explain the present results: solvent clustering, or a dependence of the solvent reorganization energy on pressure. Reorganiz ation energies of non-polar supercritical ethane were estimated from t he observed rate constant using the modified Marcus equation.