Optical absorption studies of AuCr and AuV alloy systems. (Band structure)

The optical properties of AuCr and AuV alloy systems have been investigated through a photon energy range 0.6 eV to 4 eV using an ellipsometric technique on bulk specimens. In the infrared region nearly Drude type absorptions is observed with collision frequency dependent on both concentration and impurity. The movement of the absorption edge on alloying is found to lie between the predictions of the rigid band model and of Friedel's work. Both parts of the main absorption edge are consistent with the assumption that they are associated with transitions from the d band to the Fermi level. In the case of AuCr extra absorption bands were detected compared with pure Au and these were interpreted in terms of virtual energy levels in the region of 1.2 eV from the Fermi level.