Our work has shown that europium can play a dual role by acting both as a photocatalyst for complexant destruction and, using laser-induced fluorescence, a basis for assessing the degree of such destruction achieved by photolysis. For example, it resists chemical attack by boiling nitric acid.
Europium is a heavy element ion often present in nuclear waste because it is a fission product.
The red symbols in section b of the figure are data recorded after a few hours of near-ultraviolet photolysis of the solution that had been used to record the data shown in section a. Data shown in the figure were recorded using a pulsed laser whose wavelength was tuned to 395 nm as the fluorescence excitation source. Optical filters were used to select characteristic reddish-orange emission from this state. Because the radiative decay rate of this state is so slow, many nonradiative decay processes, such as conversion of electronic energy into vibrational excitation of surrounding ligands, can be quantified via fluorescence decay rate measurements. We used a cooled photomultiplier and a signal averaging digital storage oscilloscope to measure fluorescence decay data.