Anisotropic Resistance of the Clean and Oxygen-Covered Cu(110) Surface in the Infrared

With mid-infrared spectroscopy at room temperature, we investigated the adsorption of oxygen on the clean, single-crystalline Cu(110) surface resulting in the well-known (2 × 1)­O–Cu(110) added-row reconstruction. We observed an anisotropic change of broadband reflectance which corresponds to an anisotropic surface resistance change. The resistance change is more pronounced by a factor of 7 for the plane of light incidence parallel to the [11̅0] direction. However, even perpendicular to this direction, a small but significant change is observed. A qualitative explanation of the anisotropic baseline shift can be given within existing theory, but for a quantitative description anisotropic electronic scattering of the bulk is crucial. Our results may be relevant for the optical behavior of nanocrystallites.