Kinetics of photostimulated transformations in nanosized bismuth films

Optical spectroscopy, gravimetric analysis, and microscopy studies show that irradiating bismuth films (d = 3–55 nm) with light (λ = 360 nm and I = 1.8 × 10¹⁵–7.0 × 10¹⁵ quantum cm^?2 s^?1) leads to major changes in their absorption and reflectance spectra and in film mass. The kinetic curves of the degree of photochemical transformation of bismuth films are shown to obey linear, inverse logarithmic, cubic, and logarithmic laws. The contact potential difference (CPD) of Bi and Bi₂O₃ films and the photo-electromotive force (emf) of Bi-Bi₂O₃ systems are measured. An energy band diagram of Bi-Bi₂O₃ systems is constructed. A model that includes the stages of generation, recombination, and redistribution of nonequilibrium charge carriers in the contact field of a Bi-Bi₂O₃ system, oxygen adsorption, diffusion of cation vacancies, and Bi₂O₃ formation is proposed.