Lifetime for fluorescent probe, 6-(N-(7-nitrobenz- 2-oxa-1,3-diazol-4-yl) amino)hexanoic acid (NBD), mixed into polystyrene (PS) in a film on sapphire and S-LAH79 substrates was examined as a function of temperature. Picosecond pulse with the wavelength of 430 nm was irradiated into the film from the substrate side. Information near the substrate interface was successfully extracted on the basis of evanescent wave excitation. The lifetime for NBD monotonically decreased with increasing temperature because the fractional amount of non-radiative pathways to the ground state for excited species increased with temperature. In general, as measuring temperature goes beyond a temperature at which molecular motion releases, the slope for the temperature-lifetime relationship changes. Under the condition employed, the inflection point could be assigned to glass transition temperature (Tg). The value obtained at the interface was higher than the corresponding bulk value, and this inclination was remarkable closer to the interface. Thus, it was concluded that chain mobility in the interfacial region was restricted in comparison with that in the bulk phase, and chains closer to the substrate possess less mobility.
|Number of pages||2|
|Publication status||Published - Dec 1 2006|
|Event||55th Society of Polymer Science Japan Symposium on Macromolecules - Toyama, Japan|
Duration: Sep 20 2006 → Sep 22 2006
|Other||55th Society of Polymer Science Japan Symposium on Macromolecules|
|Period||9/20/06 → 9/22/06|
All Science Journal Classification (ASJC) codes