X-ray photoelectron diffraction from a free-electron-metal valence band: Evidence for hole-state localization

X-ray-photoelectron diffraction has been measured from an Al(001) single crystal for the free-electron-like valence band and the well-localized 2s core level, using Mg K{α} radiation. Both show the same high anisotropy of 65% in the azimuthal distribution of the photoemitted electrons at 45^∘{} away from the surface normal. Moreover, the measured intensity patterns are essentially identical, indicating a strong similarity in the photoemission final states. This similarity provides evidence for a strong degree of hole localization in high-energy valence-band photoemission.