Hard X-ray Photoelectron Diffraction Applied to the System Pyrite (FeS₂) for Direct Atom Imaging by means of Chemical Sensitive Photoelectron Holography : proof of principle study

Abstract

　Photoelectron holography (PEH) is a long proposed technique for atomic structure analysis of crystalline samples. Due to a direct reconstruction of the long ranged periodic atom lattice, the atom positions as well as information about the chemical state in which one atom is bound, can be determined. This method revolutionizes the field of solid state structure analysis, as it is the first direct three dimensional structural probe for the subsurface region. Here we present a proof of principle study of our three dimensional image reconstruction algorithm by means of chemical sensitive photoelectron holography[1]. We measured the high energy angular x-ray photoelectron spectra of the iron 3p orbital signal (Fe3p) and the sulfur 2s orbital signal (S2s) for the hemisphere above a pyrite crystal sample, to capture the hard x-ray photoelectron diffraction (HXPD)patterns. Those patterns contain the holographic information of the crystal’s lattice structure and the chemical states of the lattice atoms. Unfortunately, the requirements of the reconstruction algorithm, in terms of resolution and alignment, were not met by the resulting experimental data. We have identified the key issues that impede the successful reconstruction and give an outlook on how a future HXPD experiment could be designed.