Elastic scattering and anomalous dispersion in the atomic region 13 ≤ Z ≤ 82 at 30.85 keV

We have measured the differential elastic scattering cross sections in the atomic region 13 less than or equal to Z less than or equal to 82 using nearly monoenergetic unpolarised Cs K alpha (30.85 keV) radiation at a scattering angle of 90 degrees. Experimental elastic scattering cross sections are compared with the theoretical estimates based on form factor formalisms (relativistic, non-relativistic and relativistic modified form factors). Good agreement is observed between the experimental results and the theoretical estimates. Form factors were deduced using experimental elastic scattering cross sections. Real (f') and imaginary (if '') parts of the anomalous dispersion correction components have been calculated relativistically. Experimental nonanomalous form factors were corrected for anomalous dispersion Experimental results were compared with the theoretical estimates and discussed in order to reflect the data on the current knowledge. Deviation of the experimental form factors above and below the absorption edges, and also nearer to the edges clearly indicates the need of dispersion corrections.