Excitation wavelength dependence of solvation dynamics and fluorescence anisotropy of cournarin 480 (C480) is studied using picosecond time resolved emission spectroscopy in a dimyristoyl-phosphatidylcholine (DMPC) vesicle. In the DMPC vesicle, C480 exhibits 10 nm red edge excitation shift indicating the heterogeneous nature of the microenvironment. The dynamic Stokes shift (Delta nu) and solvation time of C480 in DMPC vesicle decreases with increase in the excitation wavelength (lambda(ex)). The decay of the emission spectral width and fluorescence anisotropy of C480 in DMPC also depend on lambda(ex). (c) 2005 Elsevier B.V. All rights reserved.