LAUSR

X-ray ptychography is a scanning version of coherent X-ray diffractive imaging for reconstructing a complex transmission function of an extended object with a spatial resolution beyond the technical limitation of the fabrication accuracy of the X-ray lens [1]. One of the most important applications of Xray ptychography is a combination with X-ray absorption spectroscopy called ptychograhic-XAFS (Xray Absorption Fine Structure). This approach can discriminate chemical state of the specimen at the nanoscale from the reconstructed spatially resolved XAFS spectrum. So far, ptychographic-XAFS was applied to observe thin materials using soft X-rays [2,3]. To observe micrometer-sized bulk materials, it is necessary to use hard X-rays. A challenge towards realizing ptychographic-XAFS in the hard X-ray region was the accurate reconstruction of the weak XAFS signals. To overcome this problem, we proposed the advanced iterative phase retrieval algorithm using the Kramers–Kronig relation (KKR) between absorption and phase shift as an additional constraint. In a proof-of-principle experiment, XAFS spectra of a Mn2O3 film around Mn-K edge (6.539 keV) was successfully reconstructed [4]. Here, ptychographic-XAFS was applied to micrometer-sized three-way catalyst materials.