OICC Press International Nano Letters 2228-5326 3 1 (December 2013) 2013 01 09 Band gap determination using absorption spectrum fitting procedure 10.1186/2228-5326-3-2 EN Nader Ghobadi Physics Department, Faculty of Science, Malayer University, Malayer, IR Journal Article 2013 01 09 Abstract In this article, using the Tauc model, the absorption spectrum fitting method was applied to estimate the optical band gap and width of the band tail of the CdSe nanostructural films that requires only the measurement of the absorbance spectrum, and no additional information such as the film thickness or reflectance spectra is needed. Samples are prepared by chemical bath deposition method. Fabricated nanostructural thin films are thick but are composed from nanoparticles.