Electron and molecular processes on the surface of wide-bandgap oxides induced by photoexcitation of point defects

The step-by-step experimental investigations of mechanisms of interrelated processes in electronic and atomic subsystems on UV-VIS illuminated surface of wide-bandgap oxides are presented. A variety of complementary experimental methods such as mass-spectrometry, optical and ESR spectroscopies and UV-photoelectron spectroscopy have been adapted to carry out in situ investigations in three phases: gas-adsorbate-surface.The spectral selective and site sensitive excitation of intrinsic anion and cation vacancies in the sub-bandgap range of photon energy is discussed. The kinetic parameters of three channels of surface relaxation: radiative, non-radiative and chemi-relaxation are measured. The structure of photoadsorbed species is determined. The potentialities to regulate the number and composition of surface defects and their use for “self-sensitization” of real photocatalysts are demonstrated.