THE EXCITATION OF INFRARED SURFACE PLASMON-POLARITONS ON REFRACTORY-METALS

Observations are reported on the attenuated total reflection excitation of surface plasmon polaritons (SPP) on the refractory metals tungsten and molybdenum. Using the Otto geometry with an air gap of order 10 mu m as the tunnel barrier has allowed the excitation of SPPSs on the polished surfaces of bulk single crystals of these two metals. Reflectivities, monitored as a function of the angle of incidence of a laser beam of 3. 391 mu m wavelength, are fitted to Fresnel's theory for reflection from parallel interfaces. From such fits the dielectric constants are determined, which accord reasonably with normal spectroscopic measurements.