Surface-plasmon resonance as a sensitive optical probe of metal-film properties

The resonance excitation of surface plasmons, detected by the scattered-light method, is used in a number of experiments on Ag, Au, and Cu films. These include (i) the determination of optical constants, (ii) the use of a multilayered structure allowing sequential excitation of plasmons on both surfaces of a film, (iii) the study of interference between bulk- and surface-plasmon scattered light, and (iv) the demonstration of surface anisotropy on films grown with the metal vapor beam striking the substrate at an oblique angle. The optical-constant measurements, which were done on the substrate interface, agree with data on bulk samples prepared and measured in vacuum and with film data by Dujardin and Th\`eye, but they disagree with film data by Schulz and by Johnson and Christy. In samples grown on 77-K substrates a strong increase in bulk scattering is observed which interferes with the roughness-coupled plasmon signal producing a dispersive line shape rather than the usual Lorentzian.