Techniques for coating thin copper films on the surface of cylindrical germanium internal reflection elements are described. These films were then characterized in an aqueous environment. The expected exponential relationship between the depth of penetration of the evanescent wave into water and the thickness of the copper film was verified experimentally. The stability of vacuum-deposited copper coatings was strong enough that the internal reflection element could be exposed to an aqueous solution of a polysaccharide for more than 40 h. The weak adhesion of polysaccharides to copper surfaces was studied spectroscopically.
Teiki Iwaoka, Peter R. Griffiths, John T. Kitasako, and Gill G. Geesey, "Copper-Coated Cylindrical Internal Reflection Elements for Investigating Interfacial Phenomena," Appl. Spectrosc. 40, 1062-1065 (1986)