LUMINESCENCE LINEWIDTH BROADENING AND NONRADIATIVE ENERGY-TRANSFER STUDIES OF SOLID UO2(2+)-DATURA

The emission spectra and fluorescence decay curves of solid UO22+-Datura at liquid nitrogen temperature have been measured. The linewidth of the emission peaks of UO22+ ions in UO22+-Datura decreases with the UO22+ concentration. This linewidth broadening phenomenon can be explained by the existence of resonance interactions between adjacent UO22+-Datura species. The analysis of the emission peak position of the bound ions has been used to provide a measure of the electronic factors contributing to the interaction between the uranyl ion and phosphoryl and dicarboxyl moieties on the cell wall material. An observed blue shift of the uranyl fluorescence spectrum as a function of solution pH has been ascribed to a distortion of the normally linear O-U-O bond. An inter- and intra-molecular nonradiative energy transfer model has been successfully used to interpret the measured lifetime data of UO22+-Datura.