| ZnO and polypyrrole were probed by steady-state luminescence from pyrene and tris(2-2'-bipyridyl) ruthenium(II)(Ru(bpy){dollar}sb3sp{lcub}2+{rcub}{dollar}) respectively. Pyrene's photophysical behavior in homogeneous solvent media was compared with its emission in aqueous suspensions of ZnO and on ZnO thin films. The latter were prepared on silica supports by spray pyrolysis of zinc acetate precursor. Unlike the distinct vibronic fine structured characteristics of homogeneous solvents, a broad unstructured emission band around 393 nm was observed in the oxide suspensions. The emission was strongly quenched on the ZnO film surface. At high concentration of the pyrene probe a broad band was observed around 460-470 nm due to the formation of microcrystals on the oxide surface.; A novel technique for reversibly modulating the emission from a luminophore was developed. Using a specially-designed thin-layer cell, the luminescence from pyrene and Ru(bpy){dollar}sb3sp{lcub}2+{rcub}{dollar} could be turned "ON" or "OFF" by appropriate potential control of the polypyrrole substrate. (Abstract shortened with permission of author.)... |
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