RDS investigation of adsorption and surface ordering processes on Cu(110)

The optical anisotropy of Cu(110) has been studied at low temperatures by Reflectance Difference Spectroscopy. Distinct anisotropy features similar to those at room temperature are observed. Taking the second derivative of the measured spectrum, the main feature at 2.1 eV can be clearly separated into two peaks located at 2.0 eV and 2.2 eV, respectively. Adsorption experiments with different gases allow to attribute these two peaks to a surface state transition and a surface modified d-band transition according to their characteristic response to the adsorbates. Additionally, another modified bulk optical transition at 4.4eV is found to be particularly sensitive to phase transformations such as the (3 x 1) --> (2 x 1) phase transition of CO on Cu(110). We argue that the coverage dependent adsorbate induced surface stress is responsible for this observation. (C) 2003 WILEY-VCH Vedag GmbH & Co. KGaA, Weinheim.