X-ray photoelectron diffraction at high angular resolution

We present x-ray photoelectron diffraction (XPD) measurements at an angular resolution of ∼±1.0° which is much higher than in any prior study. Emission from the Ni 2$p_{3/2}$ core level of Ni(001) under Al Kα excitation is considered. The azimuthal XPD patterns are found to exhibit considerable fine structure not observed previously, including peaks whose full widths at half-maximum intensity are only a few degrees. The experimental data are found to be well described by single-scattering-cluster calculations with spherical-wave scattering. Fine structure due to Bragg-like scattering (Kikuchi bands) is also observed in both experiment and theory.