OPTICAL SPECTROSCOPY OF CU+/AG+ DOPED BETA''-ALUMINA

Crystalline β″-alumina doped with both Ag+ and Cu+ 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]2+ exciplex emission. Absorption of a photon by mobile monomeric ions leads to excited state dimer formation. Emission from [CuCu]2+ excimers at 550 nm and from Cu+ monomers at 400-450 nm are also observed. No emission from Ag+ monomers or [AgAg]2+ excimers is found. The Cu+/Ag+ 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. The luminescence spectrum from the written spot is different from that of the unirradiated portions of the crystal. The written spot can be erased by heating the crystal to a temperature at which the ions are again mobile. The emission, absorption, and excitation spectra of this optical memory material as a function of temperature and of the relative concentrations of Ag+ and Cu+ are discussed. © 1990, American Chemical Society. All rights reserved.