Abstract
As20Se60Tl20 bulk material was prepared firstly then thermal evaporation method was used to prepare As20Se60Tl20 films. Illumination effect at room temperature for the mentioned films has been studied within the homogeneous glass-forming region. The prepared film samples were amorphous, this is depicted by X-ray chart. Optical properties have been studied using spectrophotometric measurements. The absorption edge was shifted to shorter wavelengths due to light exposure or photobleaching effect. It was found that the extinction coefficient and the optical band gap have opposite character after illumination. (C) 2009 Elsevier B.V. All rights reserved.