Optical spectroscopy of copper cation/silver cation doped .beta.''-alumina

Crystalline {beta}{double prime}-alumina doped with both Ag{sup +} and Cu{sup +} is luminescent at temperatures between 10 and 450 K. The mobility of the ions in the conduction plane at room temperature gives rise to unusual spectroscopic properties. The dominant emission band at 640 nm originates from (CuAg){sup 2+} exciplex emission. Absorption of a photon by mobile monomeric ions leads to excited state dimer formation. Emission from (CuCu){sup 2+} excimers at 550 nm and from Cu{sup +} monomers at 400-450 nm are also observed. No emission from Ag{sup +} monomers or (AgAg){sup 2+} excimers is found. The Cu{sup +}/Ag{sup +} doped crystals exhibit optical memory. Irradiation of a spot on a crystal during cooling of the crystal preferentially forms dimers in the irradiated region which are trapped when the ion mobility decreases.