One-Step Theory View on Photoelectron Diffraction: Application to Graphene

Diffraction of photoelectrons emitted from the core 1s and valence band of monolayer and bilayer graphene is studied within the one-step theory of photoemission. The energy-dependent angular distribution of the photoelectrons is compared to the simulated electron reflection pattern of a low-energy electron diffraction experiment in the kinetic energy range up to about 55 eV, and the implications for the structure determination are discussed. Constant energy contours due to scattering resonances are well visible in photoelectron diffraction, and their experimental shape is well reproduced. The example of the bilayer graphene is used to reveal the effect of the scattering by the subsurface layer. The photoemission and LEED patterns are shown to contain essentially the same information about the long-range order. The diffraction patterns of C 1s and valence band photoelectrons bear similar anisotropy and are equally suitable for diffraction analysis.

Automated summary

This study investigates the diffraction of photoelectrons emitted from the core 1s and valence band of monolayer and bilayer graphene based on the one-step theory of photoemission. The energy-dependent angular distribution of the photoelectrons is compared to simulated electron reflection patterns of low-energy electron diffraction experiments. The results demonstrate the observable constant energy contours and the well-reproduced experimental shape of photoelectron diffraction, including the scattering resonances and the effect of subsurface layer scattering in bilayer graphene. The study also reveals that photoemission and low-energy electron diffraction patterns provide essentially the same information about the long-range order and can be equally suitable for diffraction analysis.