SOLVATION DYNAMICS OF COUMARIN-480 IN MICELLES

The picosecond time-resolved Stokes shift of the laser dye, coumarin 4 80 (I) is studied in neutral (Triton X-100, TX), cationic (cetyltrimet hylammonium bromide, CTAB), and anionic (sodium dodecyl sulfate, SDS) micelles. Above critical micellar concentration (cmc) for all three mi celles I exhibits wavelength dependent fluorescence decays and a disti nct growth at the long wavelengths. The time dependent Stokes shift st udies indicate that the water molecules in the Stern layer of the mice lles relax on the time scale 180-550 ps, which is slower than the subp icosecond relaxation dynamics observed in ordinary bulk water.