Fotocromismo em filmes finos de óxidos de tungstênio de diferentes composições

Abstract

Recebido em 22/7/02; aceito em 24/1/03 PHOTOCHROMISM IN TUNGSTEN OXIDE THIN FILMS OF DIFFERENT COMPOSITIONS. Tungsten oxide thin films with three different compositions were deposited by reactive sputtering in an oxygen-argon plasma. In a system composed of a home made photochemical reactor coupled with an optic fiber spectrophotometer, the photochromic effect was studied in these oxide films as function of UV irradiation time, in ethanol, methanol and formaldehyde atmospheres. It was observed that the photochromic efficiency depends on the vapor chemical nature where the film is irradiated as well as the film composition. Kinetic analysis suggest that two kinds of optical absorption centers should respond by the photochromic effect in these films, one generated at film surface and other inside it, which one presenting a different time constant.