Electron-transfer rate in the hexamethylbenzene-tetracyanoethylene charge-transfer complex in carbon dioxide

An electron-transfer (ET) rate in the hexamethylbenzene-tetracyanoethylene complex has been measured in supercritical carbon dioxide at various solvent densities. The ET rate increases by almost a factor of two on increasing the solvent density from the critical density to twice it. The density dependence of the ET rate is well simulated by the theory based on that of Marcus and Jortner, although the theory predicts a somewhat smaller density effect in the higher density region.