THE STUDY OF MGO(001) SURFACES BY PHOTOELECTRON DIFFRACTION

The X-ray photoelectron diffraction (XPD) technique has been used to study MgO(001) surfaces. In the angular distribution profiles from MgO, the forward scattering peaks do not always correspond to the low index crystallographic directions. This is unexpected but is also observed in the results of the multiple scattering calculations. We also observe differences between the XPD from magnesium and oxygen lines. This is apparent from the large angular shifts between the forward scattering peaks in the diffraction pattern from the two emitters, which occupy crystallographically equivalent sites. Although these peak shifts are in qualitative agreement with a model based on a rumpled MgO surface, multiple scattering calculations rule out this explanation of the anomalies.