Py scale in vapor phase and in supercritical carbon dioxide. Evidence in support of a three-density-region model for solvation in supercritical fluids

Abstract

With a fluorescence study of pyrene, Py ( I 1/ I 3) values are determined in the vapor phase at 70/dgC and in supercritical CO 2 at 45°C over a wide density range ( p r from 0.025 to 1.9.). Noise-elimination for weak pyrene vapor-phase spectra is accomplished by the application of principal component analysis. A characteristic density dependence of Py scale becomes clear with the determination of Py values at low CO 2 densities, which strongly supports a three-density-region solvation model for solvent effects in supercritical fluids.