Abstract

Although X-ray Absorption Spectra (XAS) were first measured in the 1930’s, it was not until synchrotron radiation became available in the 1970’s that it became a feasible technique and the direct dependence of the XAS on the local structure of the absorbing element recognized. By a straightforward deconvolution, the Extended X-ray Absorption Fine Structure (EXAFS) region of the XAS provides the types and numbers of and distances to neighboring atoms within 3-4 Å of the selected absorber. In addition, transitions to bound and quasi-bound final states produce features in the X-ray Absorption Near Edge Structure (XANES) region which can provide information on the electronic states and occupancies of the absorber and the three-dimensional arrangement of its near neighbors. Its ability to provide direct, structural information for any selected element in a sample in any physical state has made XAS a tool of increasing importance for deter mining local structures in metalloproteins, minerals, catalysts, and other non-crystalline systems.

© 1988 Optical Society of America