Study of Aluminum Films. I. Optical Studies of Reflectance Drops and Surface Oscillations on Controlled-Roughness Films

Ultrahigh-vacuum near-normal-incidence ultraviolet reflectance measurements on aluminum films of known rms surface roughness have confirmed recent theories of roughness-aided coupling to surfaceplasmons in free-electron-like metals and of roughness-induced light scattering. The notable success of these theories allowed the separation of experimentally observed reflectance drops into surface-plasmon-induced and scattered-light-induced components. These confirmed theories were combined with reflectance measurements to yield the surface-roughness spectra of the films studied over a spatial-frequency (wave-number) range of ≤ 1.4 × ${10}^{-2\mathrm{}}$ ${\mathrm{\AA }}^{-1\mathrm{}}$. This is believed to be the first example of the use of both surface-plasmon-induced and scattered-light-induced reflectance effects for the determination of the surface-roughness spectra.