X-ray holography: Atoms in 3D

X-ray holography is a novel method for the investigation of local atomic arrangements in solids. In conventional diffraction experiments, only the intensity of the scattered radiation is measured, its phase is lost. This loss of information makes difficult to reconstruct the atomic arrangements. In holography, both the intensity and the phase information is recorded. Using one of the atoms of the solid as source or detector of the X-radiation, atomic resolution can be reached. A three-dimensional picture of the atoms surrounding the source/detector atom can be easily reconstructed from the measured hologram. While, in principle, the measurement is very simple, in practice the small signal-to-background ratio (∼10−3) makes it difficult. Using high intensity synchrotron radiation, the measurement time can be reduced and high quality holograms can be recorded. In this paper, we review the principles and experimental techniques of atomic resolution X-ray holography and present a few examples of its application.