Anomalous scattering factor determined by semicircle fitting near theK-absorption edge of Ge

Abstract

It is shown that the locus of the f' + if'' plot in the complex plane, f' being determined from measured f'' by using the dispersion relation, looks like a semicircle very near the absorption edge of Ge. The semicircular locus is derived from a quantum theory of X-ray resonant scattering when there is a sharp isolated peak in f'' just above the K-absorption edge. Using the semicircular behavior, an approach is proposed to determine the anomalous scattering factors in a crystal by fitting known calculated values based on an isolated-atom model to a semicircular focus. The determined anomalous scattering factors f' show excellent agreement with the measured values just below the absorption edge. In addition, the phase determination of a crystal structure factor has been considered by using the semicircular behavior.

Anomalous X-ray Scattering on Semiconducting Glasses at ESRF: Review in Recent Fifteen Years

“…However, discrepancies of 𝑓 󸀠 values are frequently reported near absorption edges [4,6,27]. For example, the theoretical 𝑓 󸀠 value of Ge in GeSe 2 glass at 15 eV below the 𝐾 edge is about 14% smaller than a corrected value [17] obtained by a comparison with a result of the neutron diffraction using isotope-enriched samples [28].…”

Bragg–(Bragg)m–Laue diffraction and its interference fringe

“…The blue and red solid lines show, respectively, $P'_t /P_0$ and $P'_h /P_0$ from a thin crystal with H = 43.5 µm and L = 755 µm. Here, f 0 = 23.77, f ′ = −9.08 and f ″ = 1.13 7. The blue and red dotted lines show, respectively, $P'_t /P_0$ and $P'_h /P_0$ for a semi‐infinitely crystal.…”