Direct Imaging of Valence‐Sensitive X‐Ray Fluorescence Holograms of Fe₃O₄

Abstract

X‐ray fluorescence holography (XFH) is typically performed using zero‐dimensional detectors. This makes data acquisition in synchrotron facilities time consuming. Here, we report the first direct imaging of the X‐ray fluorescence hologram of a Fe 3 O 4 sample using a 2D hybrid detector. The apparatus, data acquisition and data processing are described here. The recorded Fe K α hologram agreed well with simulations, and the atomic images reconstructed using the SPEA‐L1 algorithm showed agreement with the expected Fe and O positions. Furthermore, by tuning the incident X‐ray energy, fluorescence from the Fe 3+ cations can be suppressed, allowing the imaging of Fe K α holograms from Fe 2.5+ cations. The valence‐sensitivity of the holograms was confirmed by the appearance of different sets of Kossel lines in the hologram, and in the atomic reconstructions. Reconstructions from the holograms from Fe 2.5+ cations show that these emitters are located on octahedral sites, and the reconstruction from the Fe 3+ holograms shows emitters on the tetrahedral sites. These results demonstrate that the new 2D hybrid detector‐based apparatus is a good XFH alternative that can be used to clarify structures of multi‐valence materials. Further applications to radiation‐damage sensitive samples, and even time‐resolved XFH experiments can also be achieved using this new XFH apparatus.