Measurement of x‐ray attenuation coefficients around K‐absorption edges using fe Kα x‐rays

Abstract The x‐ray mass attenuation coefficients were measured around the K‐absorption edges of elements in the range 16 ⩽ Z ⩽ 30 using Fe Kα x‐rays of energy 6.400 keV, which is the weighted average energy of Kα 1 and Kα 2 x‐ray components from the 57 Co radioactive source. Kβ x‐rays were almost eliminated by the differential absorption technique. The small difference in energy between Kα 1 and Kα 2 , 13 eV, was shown to be inconsequential by comparing the measured and theoretical values of μ/ρ for standard materials such as Al, Cu, Mo and Ta. The effect of fine structure of the K‐absorption edge on μ/ρ was elucidated by using the compounds of elements in the range 16 ⩽ Z ⩽ 30, containing one element with its K‐absorption edge energy ( E k ) close to the incident photon energy ( E x ). The results clearly indicate the validity of the theoretical mixture rule for all those compounds whose K edge is far away from the incident energy but show deviations of as much as 10% for the manganese compound whose K edge is 140 eV above E x and about 12% for the chromium compound whose K edge is 410 eV below E x . These deviations are attributed to the possible influence of resonance Raman scattering when the incident photon energy E x is less than the edge energy and to the influence of EXAFS when E x is more than the edge energy.