Photoinduced chesorluminescence from radical processes on ZrO2 surfaces

Photoexcitation of ZrO2 particles causes luminescence (tau similar to 15.0 s) which, after its termination, on addition of H-2 causes emission of a light pulse that displays biphasic decay kinetics (tau(1) similar to 0.9 s and tau(2) similar to 15.5 s). The latter emission is referred to as a photoinduced chesorluminescence (PhICL). At 77 K, the longer-lived emission is thermally quenched. The shorter-lived emission is caused by electron trapping by the V-a (anion vacancies) low energy traps; the longer-lived emission involves electron trapping by shallow traps, followed by detrapping and subsequent retrapping by the V-a traps. Formation of highly energetic radical species is a necessary condition to observe PhICL emission. (C) 2000 Published by Elsevier Science B.V.