THE AMPLITUDE REDUCTION FACTOR IN EXAFS

The amplitude reduction factor s(o)(2)(k) is usually treated as an emp irical parameter in EXAFS data analysis, although a few values have be en calculated [1]. We present here the results of a simple model calcu lation that gives accurate values of s(o)(2)(k) for all absorption edg es of all free atoms. The method is based on the use of Slater orbital s and the Sudden Approximation. We also calculate s(o)(2)(k) using the Tight-Binding model in order to estimate any variation in the amplitu de reduction with chemical environment. We find that s(o)(2)(k) lies b etween 0.65 and 0.80 for all edges of use in EXAFS and has a character istic dependence on atomic number. The calculated values are found to agree with a wide range of experimental data.