The spectral dependencies of quantum yields of photostimulated adsorption of oxygen on KBr and ZrO2 specimens were assessed during photoexcitation into the F centers produced by preirradiation with UV light. The spectral limits of this adsorption were shifted to wavelengths longer than the absorption band edge of the specimens. However, of great import are the spectral dependencies of the quantum yields of photochemical processes for the original state(s) of metal oxides irradiated in the intrinsic and extrinsic absorption bands. Such dependencies for the photoadsorption of donor (H2 and CH4) and acceptor (O2) molecules in gas/solid systems are reported for a variety of metal oxides of varying band gaps (E g), namely TiO2 (rutile form, E g = 3.0 eV), ZnO (3.0 eV), ZrO2 (5.0), Sc2 O3 (5.4 eV), MgO (8.7 eV), and CaO (7.5 eV) as well as for Bi2 O3 (3.2 eV), CeO2 (3.4 eV), Ga2 O3 (4.4 eV), In2 O3 (3.1 eV), Nb2 O5 (3.3 eV), and Y2 O3 (5.5 eV). The approach taken to model and compare with experimental results was reported earlier (ref ). For the first six metal oxides, the dependencies are rationalized on the basis of the absorption spectra of the specimens for which the origins of the extrinsic light absorption are known. The corresponding dependencies for the remaining oxides in the series are nonetheless also reported albeit they await characterization of the origins of the spectral features for a complete understanding to be achieved.

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This article reports the comparative activity studies of pristine and F-doped nano-ZrO 2 in photostimulated heterogeneous processes. Both samples, synthesized via a one-step flame spray pyrolysis, possess similar specific surface area (∼73 m 2 /g) and crystallites size (15 nm), while the concentration of F-anions exists as steep gradient across the zirconia radius. Photostimulated adsorption of oxygen and hydrogen was chosen as probe reactions representing the reduction and oxidation parts of photocatalytic cycle. The active states lifetime of surface active centers on pristine ZrO 2 were estimated to be 8.0 × 10 -2 s for hydrogen photoadsorption and 8.7 × 10 -2 s for oxygen photoadsorption. The corresponding values for F-doped ZrO 2 were 2.3 × 10 -2 s and 2.5 × 10 -2 s, respectively. The effect of surface photoreactions on photoinduced defect formation was studied, and the spectral dependences of the quantum yield of corresponding surface photoreactions were also measured. Comparative analysis of the experimental data provided insights for the first time that F-doping does not create new types of electronic localized states within the nano-ZrO 2 bandgap. Nevertheless, the presence of F-dopant alters the quantity of the pre-existing and photoinduced intrinsic defects in ZrO 2 , thus changing the efficiency of charge carriers recombination. The discussion of the experimental results is given within the frame of charge conservation law.