ROTATIONAL DIFFUSION DYNAMICS OF PERYLENE IN N-ALKANES - OBSERVATION OF A SOLVENT LENGTH-DEPENDENT CHANGE OF BOUNDARY-CONDITION

We report on the orientational relaxation dynamics of perylene in both its ground electronic state and its first excited singlet electronic state in the series of n-alkanes n-pentane through n-decane, n-dodecane, and n-hexadecane. We observe a curvilinear relationship between orientational relaxation time and solvent viscosity and interpret these data in terms of a solvent length-dependent change in the nature of solvent-solute interactions.