Powder diffraction with synchrotron radiation. II. Dispersion factors of Ni

Abstract

Accurate values of the absolute integrated reflections from a powder sample of Ni have been determined from measurements with synchrotron radiation as a function of scattering angle over a range of energies from 290 to 3 eV below the Ni K-absorption edge, 8332 eV. From these values, the dispersion factor f' has been determined by comparison of the experimental scattering factors with the theoretical values of Wang & Callaway [Phys. Rev. B (1977) (1984), 222, 185-188] and within about 0.5 electron units of their direct measurements by interferometric techniques in the range 30 to 3 eV below threshold. The variation of f' with scattering angle is negligibly small (less than 0.2 electron units on average). The present experiment demonstrates that powder techniques provide a simple and convenient method for the measurement off' for many materials that are not available in forms suitable for the application of other techniques such as interferometry.

Recent Advances in the Calculation and Measurement of the X-ray Dispersion Corrections

“…Inherent in this approach is the assumption that f' (CJJ,.Ii) is not a function of the scattering vector.li. Fortunately, it has been demonstrated theoretically by Kissel et aL (1980) using the S-matrix theory, and experimentally by Suortti et al (1985) and Ornote and Kato (1987), that f' (CJJ,.Ii) is not a function of .Ii.…”

The Chemically-Specific Structure of an Amorphous Molybdenum Germanium Alloy by Anomalous X-ray Scattering

“…For K absorption edges, f and f have only small variations of magnitude with k (or θ) which are commonly taken to be negligible [42,43]. (The dipole approximation yields k-independent ASFs, but including higher order terms in the calculations leads to a slight k-dependence.)…”

Dispersion corrections of the copperKedge measured by Fresnel diffraction

“…Dispersion correction measurements can be divided into two types: (i) measurements at ®nite q, and (ii) measurements in the forward direction, q = 0. The techniques that measure the dispersion corrections at ®nite q include absolute diffracted intensity (Freund, 1975;Suortti et al, 1985) and Pendello È sung (Takama & Sato, 1982) measurements. They rely on the fact that the scattered intensity and the Pendello È sung fringes depend on the structure factor, which, in turn, depends on the atomic scattering factors.…”