NONEXPONENTIAL SOLVATION DYNAMICS OF ELECTRONICALLY EXCITED 4-AMINOPHTHALIMIDE IN N-ALCOHOLS

A picosecond study of the non-exponential solvation dynamics of 4-aminophthalimide has been performed in a series of n-alcohols and some polar non-protic solvents. The results suggest single-exponential solvation dynamics in tetrahydrofuran and non-exponential in n-alcohols. The short component observed in n-alcohols is shorter than the longitudinal dielectric relaxation time of the solvent, but the average solvation time is equal to it. The short solvation time is assigned to solvent restructuring in the proximity of the excited solute molecule. Solvent restructuring should be associated with the internal rotations, like hydroxyl rotations, of solvent molecules rather than solvent reorientation. The long component of the correlation function may have its origin in the solute rotational reorientation. The role of the adiabatic intramolecular proton transfer reaction in the solvation dynamics of 4-aminophthalimide is discussed.