An Experimental Study on the Form of X-Ray Dispersion Surface by Means of Pendellosung Fringes

Abstract
It was experimentally verified that the Pendellösung fringes in the X-ray diffraction pattern of section type are of hyperbolic form in a wedge-shaped perfect crystal as predicted theoretically (N. Kato: Acta cryst. 14 (1961) 526, 627). This amounts to a direct proof to the fact that the dispersion surface of crystal waves is also of hyperbolic form. Based on this fact, a method of obtaining the structure factors by means of Pendellösung fringes is proposed. The atomic scattering factors were redetermined by this method for (511) and (444) reflections of Si single crystal: they were found to be 5.85 and 4.20 respectively. The method is useful in the cases of higher order reflections. The agreement between the present results and the previous ones (H. Hattori, et al. : J. Phys. Soc. Japan 20 (1965) 988) is satisfactory.