Optical properties of the intermetallic compounds AuAl2, AuGa2 and AuIn2

The reflectance of AuAl2, AuGa2 and AuIn2 (fluorite structure) has been measured between 0·5 and 10·3 ev. The other optical constants have been calculated by means of Kramers-Kronig relations. The results can be explained qualitatively in terms of intraband transitions, and interband transitions setting in at 2·2, 2·0 and 1·7 ev respectively. A main plasma resonance was found at 7·0, 7·8 and 7·5 ev respectively. The low energy behaviour suggests the presence of several bands of conduction electrons, in agreement with Fermi surface studies