Development of a fibre optic luminescence lifetime spectrometer
R M S Bindra R E Imhof D J S Birch
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A spectrometer for measuring luminescence lifetimes has been developed. The design includes a bifurcated fibre optic cable for delivering the light from the source to the sample and from the sample to the detector. It uses a fast photomultiplier tube as the detector, a boxcar averager for data acquisition and a PC clone for data analysis. A nitrogen pumped dye laser is used as the light source and this has a pulse width of 1·2 ns. The spectrometer has been used to measure lifetimes from a minimum of 0·75 ns (rose bengal) to 597 μs (solid uranyl nitrate hexahydrate).
A study has been made of the effects of concentration and temperature on the decay of uranyl ions (UO22+) in aqueous solution. The decay is found to be biexponential, except at temperature above 60°C, where a three-component decay analysis gives the best results for matching the data to an Arrhenius Plot. The nature of the third emissive state, appearing at high temperatures is unknown and no spectroscopic state assignment has yet been made.
R M S Bindra1 R E Imhof1 D J S Birch1
Volume 135, 2023
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