Abstract: | The effect of temperature on the optical absorption spectra and optical parameters is investigated for pure TGS and TGS doped with Cu2+ ions. Absorption measurements cover the range from room temperature to about 355 K in the energy range 3-5.5 eV. The temperature dependence of the band gap Eg(T) reveals an anomaly at the phase transition temperature for both pure and Cu2+-doped TGS crystals. In the region of the absorption edge the absorption coefficient is found to display Urbach-rule behaviour. The characteristic Urbach parameters are determined and their temperature dependence is investigated. |