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Oxygen on Cu(100): a new type of an adsorbate induced reconstruction
Affiliation:1. Department of Physics, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada;2. Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Jülich 52425, Germany;3. Jülich Aachen Research Alliance (JARA), Fundamentals of Future Information Technology, Jülich 52425, Germany;4. Experimentalphysik IV A, RWTH Aachen University, Aachen, Germany
Abstract:High resolution electron energy loss spectroscopy (EELS), Auger- spectroscopy (AES) and low energy electron diffraction (LEED) have been used to study the adsorption of oxygen on Cu(100). With increasing oxygen exposure a c(2×2) and a
></figure> R45 diffraction pattern are observed by LEED at and above room temperature. The c(2×2) pattern however always shows weak extra- <figure class=></figure>R45 spots. This is consistent with the corresponding EELS spectrum, which shows a weak dipole-active substrate phonon at 160 <em>cm<sup>−1</sup></em> which should not be dipole active for a genuine c(2×2) overlayer. These findings suggest that the <figure class=></figure>R45 structure is the only well-ordered overlayer at room temperature. By an in-situ AES comparison with a well ordered c(2×2) overlayer on Ni(100) the <figure class=></figure>R45 structure is shown to correspond, to an oxygen coverage q<sub><em>o</em></sub> = 0.48 ± 0.05. This excludes several structural models for the <figure class=></figure>)R45 structure. The EELS spectra give evidence for the adsorption of oxygen in or close to fourfold hollow sites. This indicates that the <figure class=></figure>)R45 structure can be derived from a genuine c(2×2) structure by a displacivc transition. Two structural models are proposed.</td>
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