Shallow and deep excited states of mesoscopic structure in AgI–γAl₂O₃ composites

The photoluminescence (PL) and PL excitation (PLE) spectra of superionic conducting AgI–γAl₂O₃ composites have been measured at different temperatures between 7 K and room temperature. The X-ray diffraction patterns of these composites have also been measured at room temperature. The PL intensity peak observed at 426 nm is closely connected with radiative decay of free excitons in AgI, while other emission bands are connected with shallow excited states in AgI and deep excited states at the AgI/γAl₂O₃ interface. With increasing excitation light intensity, the PL efficiencies of several emission bands become saturated, except for the free exciton band. These results may give important information about the origins of the high ionic motion in these composites.