The free-electron response in reflectance anisotropy spectra

Abstract

Reflectance anisotropy spectra (RAS), extended into the near infrared spectral region, of anisotropic metal islands, metal surfaces, and atomic nanowires are analyzed with respect to anisotropies in the optical response of the free-electron gas of such low dimensional metal structures. In order to distinguish conductivity and morphology effects, both a phenomenological anisotropic Drude model and an effective medium model using ellipsoidal metal inclusions are used to model the spectra. In some cases (metal islands) the RAS response is dominated by the free-electron contribution, while this contribution is significantly smaller for the metal surfaces and nanowires in the accessible spectral range.