The probing depth of conversion electron/He ion yield XAFS methods has been studied in order to apply these methods to estimate the local distortion of strontium titanate thin films on thick substrates. Several strontium titanate thin film samples with different thicknesses were prepared and the edge-jump amplitudes at both the Sr and Ti K-edges were obtained. The probing depths were estimated to be 300 nm for the Sr K-edge and 30 nm for the Ti K-edge by the conventional exponential fit. The XAFS spectra and the probing depths measured by conversion electron and He ion yield methods is much the same, though the background curves are different.Keywords X-Ray absorption fine structure, conversion electron yield, probing depth, strontium titanate, thin film Fig. 1 Schematic diagram of the CEY/CIY XAFS apparatus.

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It is known that the dielectric constant of SrTiO3 thin film deposited on a thick substrate decreases with decreasing the thickness. This may be related with local atomic distortion in SrTiO3 thin film. In order to detect the atomic distortion, Sr and Ti K-edge XAFS spectra were measured with a total-conversion electron/He ion-yield (CEY/CIY) apparatus which is easy to build and to operate. We confirmed the validity of our fabricated CEY/CIY apparatus and applied it to XAFS measurement of SrTiO3 thin films. Fourier transforms of XAFS at different thicknesses suggested the local distortion induced by the internal stress in thin films.

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We have measured XAFS spectra of metal surfaces corroded with melting salt (NaCl, KCl, and Na2SO4). Steel samples used were S45C, SCM435, SUS310S, and SUS304. We measured the Fe K-edge XAFS spectra for all samples and the Ni K-edge for SUS310S and SUS304 samples before and after the corrosion. The XANES spectra of samples before the corrosion show metallic structure because surface oxide thickness is thinner than probing depth with a conversion yield XAFS method. Each result of these XAFS spectra gives good agreements with the FEFF calculation in the assumption of bcc and/or fcc structure. The Fe K-edge spectra of steel samples except SUS310S after corroded treatment show existence bonding between Fe and another light element although the spectra of SUS310S samples before and after corroded treatment are much the same.