Fig. 11. Thickness map of a single LSF particle reduced in pure hydrogen at 973 K for 1 h as obtained from scanning Fe Kα X-ray fluorescence mapping (large panel) and spatially-resolved Fe K-edge XANES spectra for the marked points (shown as insets). The latter can be separated into two distinct classes: bulk (1 and 2) and surface (3–5). The measurements were conducted in flowing He.