SOLVATION DYNAMICS OF A COUMARIN DYE AT LIQUID SOLID INTERFACE LAYER - PICOSECOND TOTAL INTERNAL-REFLECTION FLUORESCENCE SPECTROSCOPIC STUDY

Fluorescence rise and decay curves of coumarin 460 in 1-butanol/sapphire interface layer were measured by time-resolved total internal reflection fluorescence spectroscopy. The fast rise and decay components due to the solvent relaxation became slow in the interface layer, and the anomaly was observed up to the penetration depth of 100 nm. The result was interpreted in terms of the longitudinal relaxation of 1-butanol affected by hydrogen bonding interactions between the hydrophilic sapphire surface and 1-butanol.