SOME RECENT TECHNIQUES USING X-RAYS FOR THE INVESTIGATION OF CONDENSED MATTER

A commonplace in the history of X-rays is the exponential increase of the brilliance of sources with time, which has allowed one eventually to use all the possible interactions of X-rays, considered as electrom agnetic waves, with matter. The aim of this brief review is to discuss some of the most promising developments, in particular at third gener ation synchrotron sources. Imaging techniques (tomography, microscopy and holography) are discussed after a brief historical introduction. A ll these methods have greatly benefited from developments in X-ray opt ics: multilayers, Fresnel and Bragg-Fresnel optics, capillary optics. A review of recent progress in spectroscopy is given as well: EXAFS, n ear-edge adsorption spectroscopies (NEXAFS, XANES) and fluorescence sp ectroscopies, resonant Raman effect, resonant Auger effect, and finall y magnetic dichroism. This section ends with a discussion of recent in elastic scattering experiments. Methods related to scattering and diff raction will be discussed in the last section: in particular standing waves, hologaphy, magnetic scattering and techniques for the structura l investigation of surfaces (grazing incidence diffraction and diffuse scattering, reflectivity). Finally, new possibilities making use of t he coherence of the beam (photon correlation spectroscopy) will be dis cussed.