Site-Specific Orbital Angular Momentum Analysis of Graphite Valence Electron Using Photoelectron Forward Focusing Peaks

Abstract

Two-dimensional photoelectron intensity angular distributions of the graphite valence band were measured using circularly polarized soft X-ray with a photon energy of 500 eV. Photoelectron intensity from the bottom of the 2 s band was observed at the Γ point of every other Brillouin zone reflecting the photoelectron structure factor, that corresponds to the interference of photoelectron waves from 2 s atomic orbitals within a unit cell. Simultaneously, the circular dichroism of photoelectron forward focusing peak rotation around the incident-light axis was observed. This rotation in the photoelectron intensity angular distribution from the 2 p x y band was about twice those from 2 s and 2 p z bands, reflecting the difference in orbital angular momentum of each band. Taking advantage of the forward focusing peak as a site-specific probe, the local orbital angular momentum of each valence band was analyzed. The origin of the dual behavior that appeared in the observation of local angular momentum from a delocalized valence band is discussed in conjunction with the dispersion and spatial origin of the electron.