Recent developments of the wavelength-dispersive XAFS technique in the soft X-ray region

The wavelength-dispersive XAFS (X-ray absorption fine structure) technique, by which a XAFS spectrum is recorded at once without monochromator scan, is suitable for tracing high-speed phenomena such as surface chemical reactions, in which a frequent repetition is hardly expected. Although only about ten years have been past from the development of the technique, the time resolution has been greatly improved, and a continuous measurement with a 33 ms time resolution is achieved at present. Moreover, it has very recently been demonstrated that the orientation of adsorbate, as well as the amount of each chemical species, is traced within one chemical reaction, by combining the wavelength-dispersive XAFS with switching between the vertical and horizontal liner polarizations. (author)