Stereo atomscope and diffraction spectroscopy—Atomic site specific property analysis

Abstract

Direct three-dimensional atomic structure analysis by stereo atomscope, valence-band angular momentum analysis by circularly polarized photoelectron diffraction, and atomic-layer-resolved magnetic structure analysis by diffraction spectroscopy are reviewed. The circular dichroism of photoelectron forward focusing peak rotation around the incident-light axis reflects the orbital angular momentum of excited core level and is inversely proportional to the distance between the emitter and scatterer atoms. This is the basis for the stereo photograph of the atomic arrangements. Furthermore, these rotations are also found in the case of the valence band photoelectrons. The rotation corresponds to the orbital angular momentum quantum number of valence band. Simultaneously, the photoelectron structure factor, that corresponds to the interference of photoelectron waves from atomic orbitals within a unit cell, was observed. The origin of the dual behavior that appeared in the observation of local angular momentum from a delocalized valence band is discussed. Lastly, local electronic and magnetic structure information has been obtained by diffraction spectroscopy. X-ray absorption and magnetic circular dichroism spectra from different atomic layers of the Ni thin film were disentangled by use of Auger electron diffraction. Surface and interior core-level shifts and magnetic moments are determined for each atomic layer individually.