X-ray absorption spectroscopy is a relatively old experimental technique
that has been revitalized by technological and theoretical progress during the
past several years. The development of a powerful synchrotron radiation source
at the Stanford Synchrotron Radiation Laboratory (SSRL) (29) has provided
experimenters with x-ray fluxes several orders of magnitude higher than those
previously obtainable from conventional x-ray tubes. Furthermore, theoretical
understanding of the extended x-ray absorption fme structure (EXAFS) has
advanced to the point where reliable structural information can now be extracted
from x-ray absorption spectra. The combined effect of these developments
has made feasible both the collection and interpretation of data on dilute
systems such as metalloproteins. In its applications to bioinorganic
chemistry, as well as amorphous materials, catalysts, and surfaces, x-ray
absorption spectroscopy has already provided structural information that was
inaccessible by conventional methods.