Optical Absorption of Copper and Copper-Rich Copper Nickel Alloys at Room Temperature

Abstract

The optical absorption of Cu and Cu-Ni alloys was measured on solid samples at room temperature. Light in the visible and ultraviolet region was used. It was found that the wavelength position of the main absorption edge did not change with alloying. It disappeared, however, for alloys with 20 and 25 at.% Ni. The position of the secondary absorption peak moved slightly to lower wavelengths with increasing nickel concentration. The measurements indicate that the optical properties of Cu-Ni alloys cannot be described with a rigid-band model. It is more likely that the addition of nickel to copper creates "virtual energy states," instead of shifting the Fermi energy.