This research equipment grant is for the purchase of fluorescence lifetime and transient fluorescence equipment to be used primarily by the two co-PIs Torkelson and Lewis as well as other researchers at Northwestern. Torkelson's research is the application of fluorescence and phosphorescence techniques in the study of basic issues elated to polymer science and engineering: diffusion-limited interaction in polymer solutions, phase separation in polymer blends and in block copolymer systems in solution and the bulk state, the distribution of local free volume and its sensitivity to physical aging in polymer glasses, and polymer-polymer interpenetration, interdiffusion, and correlations in homopolymer and block copolymer systems. The focus of Lewis' research is the investigation of reactions which occur via electronically executed complexes which are used to establish the role of exciplexes and radical ion pairs in reactions of fundamental importance to organic photochemistry such as cycloaddition and proton transfer. Near term uses planned for the instrumentation include: the study of diffusion-limited interactions in polymer solutions which may lead to a better understanding of the gel effect in free radical polymerization; investigation of phase separation phenomena and compatibilization in block copolymers solutions, blend with homopolymers, and in the bulk state; intermolecular correlations in homopolymers, block copolymers and polymer blends; obtaining local free volume distribution in amorphous polymer systems; determination of the mode of diffusion in polymer welding phenomena (interdiffusion across a polymer-polymer interface); characterization of the basic photophysics of polymer systems; excimer and exciplex kinetics studies; and investigations of excited state of Lewis acid complexes.
