INORGANIC SOLVENT SYSTEMS FOR LANTHANIDE IONS

Lanthanide ions dissolved in low vibrational frequency inorganic liqui ds have potential applications in laser systems requiring long non rad iative lifetimes such as mid infrared and up conversion lasers. The us e of liquids, whilst presenting some thermal and technological problem s, avoids costly crystal growth and fabrication and gives great flexib ility in varying lanthanide species, doping levels and co-doping. We r eport an extensive study of solvent systems based on POCl3, PSCl3, PBr 3, PCl3, AsCl3, SbCl3 and SbBr3. The relatively well known POCl3 syste m is found to show a far more complex behaviour than the early literat ure suggests because of formation of the adduct 2POCl(3):SnCl4. The ot her species except for PBr3 and PCl3 prove unsuitable owing to the rea dy production of absorbing species. PBr3 and PCl3 produce solvent syst ems when combined with the Lewis acids AlBr3 and SbBr3 or AlCl3 and Sb Cl3 respectively. The energy levels of all laser relevant lanthanide i ons below similar to 20000 cm(-1) were determined in the PBr, solvent system, and correlations between the required Lewis acid concentration and the lanthanide element found. Comparison of the spectra in variou s solvents leads to preliminary conclusions about the lanthanide ion c oordination.