Excitation wavelength dependence of solvation dynamics of coumarin 480 in a lipid vesicle

Excitation wavelength dependence of solvation dynamics and fluorescence anisotropy of coumarin 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 (Δν) and solvation time of C480 in DMPC vesicle decreases with increase in the excitation wavelength (λex). The decay of the emission spectral width and fluorescence anisotropy of C480 in DMPC also depend on λex.