The Kinetic Study Of The Ultrafast Electron Transfer From Sensitized Dyes To Silver Halide Microcrystals

On the basis of picosecond time-resolved fluorescence spectroscopy, we studied the spectral sensitization micromechanism of four cyanine dyes J-aggregate absorbed on the tabular and cubic AgBr microcrystals with different concentration. We detailed analyzed the dependence of the electron transfer and the efficiency of spectral sensitization in the dye sensitized system on different conditions.With the time-resolved fluorescence spectroscopy, we found that the fluorescence decay curves of cyanine dyes J-aggregate of dye1798, dye 55026 and dye 8701 absorbed on the tabular and cubic AgBr microcrystals are fitted by a sum of the double exponential functions, and the fitting curves are consisted of a fast and a slow components. Because of the large amplitudes of the fast decay, this fast decay should be mainly attributable to the electron transfer from J-aggregate of dye to conduction band of AgBr. The fluorescence decay curves of J-aggregate of dye B1251 absorbed on two types of AgBr microcrystals are fitted by a sum of two and three exponential functions, respectively. We found that there is a fast component in all the fitted curves. In this paper, we found the sensitized efficiency of dye 8701, dye B1251 and dye 55026 of low concentration for cubic AgBr microcrystals is higher than that of the tabular. In contrast, the sensitized efficiency of dye 1798 and dye 55026 of high concentration for cubic is lower than that of the tabular. So the research provides the development and applications of the dye-sensitized system of photosensitive emulsion with theories foundation.