Optical spectra and analysis for Pr3+ in SrAl12O19

Energy levels of the 4f(2) electronic configuration of Pr3+ in SrAl12O19 (SAM) have been determined from polarized absorption and fluorescence spectra using crystals, charge-compensated with Mg2+, at temperatures between about 20 and 300 K. Energy level assignments were made initially by comparing the crystal spectra with energy levels calculated by using crystal-field parameters, B-km, compatible with those previously reported for Nd3+ in SAM. The B-km were varied to obtain a best fit between experimental and theoretical energies, and the final values: B-20=-94, B-40=1047, B-60=-1397, and B-66=-1245 cm(-1) give an rms fit of 14.5 cm(-1). The B-km for Pr3+ in SAM were also used along with a result relating the B-km to crystal-field components, A(nm), derived in a lattice sum calculation to obtain B-km values for all the triply ionized rare-earth ions in SAM. Odd-fold A(km) are also given that are required in the intensity and lifetime calculations and yield results in good agreement with the measurements. In addition, the results of our energy level fitting were useful in estimating absorption and emission cross sections, as well as lifetimes and branching ratios, for the Various J multiplets. The evidence given here that the room temperature fluorescence quantum efficiency of P-3(0) in lightly doped Pr in SAM is near unity strengthens the case that this is a potentially useful laser material. The theoretical model and method of analysis used is useful for the calculation of energy levels, wave functions, transition probabilities, etc., for any rare-earth RE(3+) ion in any host of known crystal structure. (C) 1997 American Institute of Physics.