ANOMALOUS X-RAY ATTENUATION COEFFICIENTS AROUND THE ABSORPTION EDGES USING MN K-ALPHA AND CU K-ALPHA X-RAYS

The x-ray attenuation coefficients for three elements and for eight compounds are determined, adopting the method developed by us employing a proportional counter, with a view to study the effect of fine structure on the mass attenuation coefficient values using Mn K,and Cu K, x-rays derived from K x-ray emitters, Fe-55 and Zn-65 radioactive sources, by a differential absorption technique. It is experimentally established that a small difference in energy between K-alpha 1 and K-alpha 2 (11 eV in the case of Mn K,and 24 eV in the case of the Cu K-alpha x-ray) is inconsequential by comparing the measured and theoretical values of mu/rho for standard elements, aluminium, copper and tantalum. The effect of fine structure on mu/rho values is studied using the compounds containing one element with its absorption edge close to the incident photon energy. Results obtained in the present investigation show the nonvalidity of the mixture rule above the edge and also below the edge, ranging from about 600 eV below the edge to about 1500 eV above the edge. The contribution of resonance Raman scattering to the attenuation coefficient and indications to the presence of pre-edge structure similar to EXAFS are discussed.