The influence of incommensurability on the long-range periodicity of the Pd(100)-(5×5)R27°-PdO(101)

Research output: Contribution to journalArticle


The structural model of the (5×5)R27°-PdO(101) surface oxide grown on Pd(100) has been proposed and refined by a number of authors over more than a decade. In the current contribution we discuss the long-range periodicity of this structure arising along one of the crystallographic directions due to its incommensurability with the substrate. Analyzing the results of surface sensitive diffraction studies, we determined a slight distortion of the previously reported perfect (5×5)R27° surface oxide unit cell. Considering it, we were able to achieve both qualitatively and quantitatively better fit to the experimental diffraction data than it was possible for the perfect structure. Further, taking into account the experimentally obtained scanning tunneling microscopy data and closely examining high-resolution patterns recorded by means of high-energy surface X-ray diffraction, we developed a qualitative structural model based on a larger non-orthogonal surface unit cell to shed more light on the long-range order of the PdO(101) surface oxide. The model comprises a shift of the atoms of the PdO perpendicularly to the direction of the incommensurability to correct for it. This structural model reproduces the fine details of the high-resolution diffraction patterns and qualitatively explains the periodic stripes of structural distortion observed in the images recorded by a scanning tunneling microscope.


External organisations
  • German Electron Synchrotron (DESY)
  • University of Siegen
  • University of Hamburg
  • Chalmers University of Technology
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Sciences


  • CO oxidation, Heterogeneous catalysis, Pd, PdO, STM, Surface X-ray diffraction, Surfaces
Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalSurface Science
Publication statusPublished - 2017 Jun 1
Publication categoryResearch