Large angle elastic and inelastic scattering of 14.93 keV photons

Abstract

Elastic and inelastic scattering cross-sections for the 14.93 keV photons (Y-Kα X-rays) were measured at an angle of 141° in the elements with 6 ⩽ Z ⩽ 92 and 1 ⩽ Z ⩽ 50, respectively. A reflection mode geometrical arrangement involving a Y-foil excited by the 59.54 keV γ-rays from the 241Am radioisotope as photon source and an HPGe/Si(Li) detector was used. The measurements were performed under vacuum ∼10 −2 Torr. Special care was taken in determination of the incident photon intensity and geometrical factors and to check effects due to occurrence of Bragg diffraction from the target lattice. The measured elastic scattering cross-sections have been compared with predictions from the form-factor formalism and relativistic second-order S-matrix calculations. The modified form-factor (MF) cross-sections are higher up to 50% than the measured ones in the case of elements with the electron binding energy (BE) in vicinity of the incident photon energy and are lower up to 20% for the other elements. These deviations are smoothed by incorporating the Anomalous Scattering Factors (ASFs) to the MF values [Acta Cryst. A 46 (1990) 170]. The S-matrix values exhibit general agreement with the measured cross-sections. The measured inelastic scattering cross-sections are found to be in good agreement with those calculated using the Klein–Nishina cross-section incorporating the Hartree–Fock incoherent scattering function (ISF).