The Role Of Plasmons And Interband Transitions In The Color Of Aual2, Auin2, And Auga2

First principles calculations of the optical properties of the intermetallic compounds AuAl2, AuIn2, and AuGa2 have been performed. Analysis of the dielectric functions showed that AuAl2 is unique because a bulk plasmon is seen in the optical region and contributes to the purple color of this material. An experimental electron energy-loss spectrum showed excellent agreement with the theoretical prediction and confirmed the presence of the bulk plasmon. (C) 2011 American Institute of Physics. [doi:10.1063/1.3638061]