The oxidation of Pd(100) and the formation of PdO was studied in situ using surface x-ray diffraction. A bulklike, epitaxial PdO film is formed at oxygen partial pressures beyond 1 mbar and sample temperatures exceeding 650 K. The main orientation is PdO(001)/Pd(001), based upon bulk reflections from the PdO film. By comparing with measurements from the Pd crystal truncation rods, we estimate an rms surface roughness of 6 Angstrom, in good agreement with previous high pressure scanning tunneling microscopy measurements. Finally, we observed the transformation from the (root5 x root5) surface oxide to PdO bulk oxide at 675 K and 50 mbar O-2 pressure.
- Atom- och molekylfysik och optik