Time-resolved fluorescence analysis for dye-labeled polystyrene in thin films

Time-resolved fluorescence spectroscopy and anisotropy were applied to dye-labeled polystyrene in thin films. Both fluorescence lifetime and rotational relaxation time decreased with decreasing thickness once the film became thinner than approximately 100 nm. The results could be well reproduced by a tri-layer model composed of surface, interface and bulk regions. The model analysis clearly indicates that the chain dynamics in the surface and substrate interfacial regions is, respectively, faster and slower than that in the internal bulk phase.