Propagation distance of surface electromagnetic waves on two metal-oxide-air systems

The propagation distance of surface electromagnetic waves on a copper-cuprous oxide-air system was measured using two prism couplers, for oxide thickness between 20 A and 2000 A, and wavelengths from 9.2 μm to 10.8 μm. The copper sample consisted of an evaporated copper film on glass, with an oxide film overlayer grown by heating in air. The measured values of propagation distance agree well with computer-calculated solutions of the three-media dispersion relation. Similar measurements made on a polished surface of rolled titanium, oxidized by heating in air, give agreement only to within 50%. Auger analysis indicated that a carbide impurity on the highly reactive titanium surface and a variation of the titanium oxide composition with thickness both contributed to the disagreement between measured and calculated values of propagation distance.