Time-resolved fluorescence measurements for dyes in polymer ultrathin films based on guided wave mode excitation

Fluorescence lifetime of Coumarin 153 dispersed in ultrathin films of ARTON-F5023® was examined on the basis of Guided Wave Mode Excitation. The polymer containing dyes was spin-coated onto 150 nm thick-PVA (poly(vinyl alcohol)) film / 35 nm thick silver / glass plate system Mode-locked Ti:sapphire picosecond laser at 440 nm was introduced from the substrate side under the condition that guided wave mode (GWM) excitation was attained. Fluorescence from dyes in the film was detected as a function of time using a streak camera. Once the film became thinner than 100 nm, fluorescence lifetime increased with decreasing thickness, measuring that molecular motion in ultrathin films was depressed in comparison with that in the bulk. This might be because an interfacial effect between ARTON-F5023® and PVA films became dominant over the surface effect, which activates molecular motion. More conclusive discussion will be presented in a poster.