MICROENVIRONMENTS OF 8-ANILINO-1-NAPHTHALENESULFONATE AT THE HEPTANE-WATER INTERFACE - TIME-RESOLVED TOTAL INTERNAL-REFLECTION FLUORESCENCESPECTROSCOPY

Picosecond time-resolved total internal reflection fluorescence spectr oscopy was applied to study the microenvironments of 8-anilino-1-napht halenesulfonate molecules at the heptane-water interface. By analyzing the fluorescence decay profiles, it was found that the fluorophores i n the vicinity of the interface are present in two different solvated structures, One of them is located up to a few nanometers from the int erface, and the other is located in a relatively wide range toward the aqueous phase. The former solvated structure is the cause of a long f luorescence lifetime which reflects the low polarity or the extremely high viscosity of the microenvironments.