Temperature Dependence of Local Density Augmentation around Exciplex in Supercritical Water

Abstract

Local density augmentation around exciplex between acetophenone and N,N,N',N'-tetramethylbenzidine in supercritical water was measured by peak shift of transient absorption spectrum at various temperatures from 380 to 400°C and pressures from 6 to 37 MPa. Large local density augmentation was observed at lower densities. The excess density, defined by the difference between local density and bulk density, exhibited a maximum at approximately 0.15 g cm^-3, which suggests large solute-solvent interaction. The local density augmentation decreased with an increase in temperature, however, local density augmentation still existed at 400°C, which is probably caused by strong solute-solvent interaction.