Electron exchange and oxygen rearrangements on photoactivated oxide surface

The step-by-step experimental investigations of mechanisms of interrelated processes in electronic and atomic subsystems on UV-VIS. illuminated surfac e of wide bandgap oxides are presented. The variety of complementary experi mental methods such as the mass-spectrometry, the optical and ESR spectrosc opies, UV-photoelectron spectroscopy have been adapted to carry out in situ investigations in three phases: gas-adsorbate-surface. The origin of excitation of electron subsystem in the above-bandgap range a s well as in the sub-bandgap range of photon energy is discussed. The natur e of metastable state of photoexcited surface and the role of photodesorpti on and photoadsorption of oxygen in energy relaxation is treated. Using the time-of-flight spectroscopy the composition and the kinetic energy distrib utions of arising photodesorbed particles are analyzed. The dynamics of bon d rearrangements and bond breaking is discussed in the framework of charge transfer approach in excited clusters. The potentialities of the presented results for probing and characterizatio n of the electronic and atomic structure of active sites on the surface as well as for regulation of the number and composition of surface defects are discussed.