Photostimulated changes in WO3 nanosized films

• Published in: Russian Journal of Physical Chemistry A Vol. 84; no. 8; pp. 1401 - 1405
• Main Authors: Surovoi, E. P., Bin, S. V., Borisova, N. V.
• Format: Journal Article
• Language: English
• Published: Moscow Nauka/Interperiodica 01.08.2010
• Subjects: Chemistry; Chemistry and Materials Science; Physical Chemistry; Physical Chemistry of Nanoclusters and Nanomaterials; Incident Light Intensity; Absorption Band Edge; Short Wave; Nonequilibrium Charge Carrier; Photochemical Transformation
• ISSN: 0036-0244; 1531-863X
• DOI: 10.1134/S0036024410080224

During the irradiation of WO 3 films d = 7–160 nm thick by light at λ = 320 nm ( I = (1.5–7) × 10 15 quantum cm −2 s −1 ), absorption band at λ = 850 nm appeared along with absorption band edge shift to shorter waves. The subsequent irradiation of samples at λ = 850 nm caused the disappearance of the longwave absorption band. The intrinsic absorption edge of WO 3 films was determined (λ = 320 nm). The degree of transformations of WO 3 films increased under atmospheric conditions as the intensity of incident light and the time of irradiation (1–140 min) grew and as film thickness decreased. A mechanism of photochemical transformations of WO 3 films was suggested. This mechanism included the generation of electron-hole pairs, the recombination of part of nonequilibrium charge carriers, the formation of [eV a 2+ e] centers, and the isolation of photolysis products.