Photoelectron Diffraction and Holographic Reconstruction of Graphite

A series of two-dimensional photoelectron angular distributions from a graphite single crystal for different kinetic energies from 311 to 908 eV using circularly polarized soft X-ray was measured. We realized that the directions of the prominent peaks arranged in a hexagon appearing in the photoelectron diffraction patterns and the directions from a photoelectron emitter atom to the surrounding atoms, which we previously assigned as the corresponding scatterer atoms [Appl. Phys. Lett. 85 (2004) 3737], do not match. From the comparison of the photoelectron diffraction patterns with multiple scattering calculations for each atomic site, we corrected our earlier assignments and revealed that the signatures of such peaks are even found in the photoelectron diffraction pattern of monolayer graphene. In the case of graphite that has a large interlayer separation, the diffraction rings due to in-plane scattering become dominant over the forward focusing peaks owing to interlayer scattering. Furthermore, a holographic reconstruction algorithm based on the fitting of elemental diffraction patterns for various C-C bond distances was used to analyze the full set of measured data. Clear nanometer-scale real-space images of several graphite layers were reconstructed.