HIGH-SPATIAL-RESOLUTION XAFS AND ITS IMAGING APPLICATIONS

A synchrotron X-ray microprobe has been applied to XAFS measurements over a small region. Either an ellipsoidal mirror or a modified Kirkpatrick-Baez configuration is used as an X-ray focusing element in combination with a double crystal monochromator. The X-ray beam size at the sample is around 5 mum with a photon flux of 10(7) to 10(8) photons/s/300 mA. Minerals in thin sections of rock samples have been analyzed. For analysis of practical samples, fluorescence detection is useful and effective. Deformation of the XAFS spectrum due to a self-absorption effect has been experimentally minimized using the small exit-angle condition; it can also be numerically corrected using physical parameters. Chemical state imaging has also been carried out using the chemical shift of the absorption edge. Lateral distributions of magnetite and hematite in a sintered iron ore have been obtained.