T-1 RELAXATION OF PERYLENE IN FLUID ETHANE - PRESSURE-DEPENDENT CHANGES IN SHORT-RANGE ORGANIZATION

We report our measurements of vibrational population relaxation of the nu(7) (1375 cm(-1)) mode of perylene in ethane at a series of fluid p ressures, The data show that T-1 decreases with increasing fluid press ure and that the dependence of T-1 on pressure is not consistent with predictions based on simple spatial or stoichiometric considerations, The data indicate a nonrandom orientational distribution of the solven t molecules about the solute where the portion of the solvent environm ent sensed by the perylene nu(1) coordinate changes from one ordered s tate to another ordered state with increasing pressure.