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

摘要

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 subbandgap 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.