Die optischen Eigenschaften von Gold, Silber und Gold-Silber-Legierungen zwischen 2 und 40eV aus Energieverlustmessungen

Abstract

The energy loss functions Im$\left( { - \frac{1}{\varepsilon }} \right)$ of Au, Ag and Ag-Au alloys are determined from energy loss spectra of fast electrons, using different methods in the energy regions 2 to 4 eV and 4 to 40 eV. The optical constants ɛ₁ und ɛ₂ are calculated from the energy loss functions by Kramers-Kronig analysis.

The experimental results show a different dependence in the optical behaviour of the alloy on the alloying component: if Au is added to Ag, the effect on the optical properties is stronger than in the reverse case. Between 50 and 70 at.% Au in the alloy the specific properties of Ag and Au vanish completely.

An interpretation of the energy loss maxima as surface plasma oscillation, volume plasma oscillation and interband transition is attempted.