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(Color online) Measured Ti (left panel) and S (right panel) -edge XANESs. Curve (a) is for pure (unannealed) sample, while curves (b)–(e) are for that has been annealed in air for at temperatures of 200, 300, 400, and , respectively. The spectrum of a pure is shown with a dashed curve (f).
(Color online) Sulfur -edge XANES of the annealed sample before (dashed curve) and after (solid curve) being washed with water. The lower-energy features (peaks P1 and P2), corresponds to S in the bulk, while the features in the higher-energy region (P3–P5) correspond to S at the surface. Left inset: comparison between the measured XANES in the lower-energy region (bottom curve) with the simulation for bulk S defects (from top: and ) in . The difference between the spectrum befre and after washing is compared to the simulated XANES of S on surface in the form of . The absolute photon energy of simulated spectra was slightly shifted (all shifts are smaller than ) to align a particular feature with the measured spectra.
(Color online) Atomic structures of (a) bulk anatase and (b) sulfur interstitial with a zoom view of the latter on the far right. The large, medium, and small spheres are Ti, S, and O atoms, respectively. The dashed ellipse indicates the split-interstitial S–O pair. The arrows show the relaxation of the neighboring atoms compared to their positions in the bulk. In the zoom, the bond distances from S to its neighbors are given in angstroms and an additional O, from an adjacent unit cell, appears.
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