Spectroscopic study of 4-aminobenzophenone in supercritical CF 3H and CO 2: local density and Onsager's reaction cavity radius

Abstract

The measured bathochromic shifts of 4-aminobenzophenone (4ABP) in CF 3H are explained by Onsager's reaction field theory (ORFT) if the cavity radius is the sum of Van der Waals radii of solute and solvent, while in CO 2, the cavity radius is the solute's Van der Waals radius. The experimental local densities around 4ABP have been estimated and show a maximum at a reduced density of 0.5 for CF 3H and 0.7 for CO 2. Simulations are consistent with the high local densities found at low bulk densities and suggest possible explanations for the different radii used for CF 3H and CO 2.