Solvation dynamics in organized assemblies. 4-aminophthalimide in micelles

Solvation dynamics of 4-aminophthalimide (4-AP) has been studied in neutral (triton X-100, TX), cationic (cetyl trimethyl ammonium bromide, CTAB) and anionic (sodium dodecyl sulfate, SDS) micelles using picosecond time resolved Stokes shift. Above critical micellar concentration (CMC), fbr all the three micelles, 4-AP exhibits wavelength dependent fluorescence decays with a fast decay at the blue end and a slow decay accompanied by a distinct growth at the red end of the emission spectra. The time dependent Stokes shift indicates that the water molecules in the Stern layer of the micelles relax in approximate to 100 ps time scale which is markedly slower than the subpicosecond relaxation dynamics observed in ordinary bulk water. (C) 1998 Elsevier Science B.V.