Preparation and Properties of Potential Green Laser Materials Containing Hexavalent Uranium

摘要

Since the uranyl ion appeared to be suitable as the basis for laser material oscillating in the green region of the spectrum, attempts were made to produce a crystalline laser material incorporating the uranyl ion. When attempts were made to grow crystals of a number of pure uranyl compounds, only a few could be produced as large, optically perfect single crystals, and these proved insufficiently resistant to mechanical and thermal shock to be practical-laser materials. Uranium-activated lithium and sodium fluorides were investigated and found to be potentially suitable. A detailed spectroscopic study was made of the energy levels of the uranium activator, and the luminescent center identified as the ion UO2F4(2-). An assignment of the lines in uranium-activated lithium fluoride showed that the energy level system was suitable for four-level laser oscillation. When samples of the uranium-activated fluorides were fabricated and tested in Fabry-Perot resonators, no laser oscillation was observed. However, the fluorescence appeared to show a short period of stimulated emission, followed by an anomalously long period of decreased intensity caused by depopulation of the metastable level by upward transitions. (Author)