Determination of Phase Angles and Absolute Values of the Structure Potential V0002of Cadmium Sulfide from Equal Thickness Fringesin Electron Micrographs

Abstract

Abstract Fringe spacings were measured at the three different diffraction conditions: 0002-Bragg position, 0004-Bragg position and the symmetric position for 000l systematic reflections. The absolute value |V0002| and the phase angle Φ0002 were determined by analyzing the ratios of fringe spacings with a 15-beam calculation. The values determined were |V0002| = 6.5 ± 0.5 Volt and tan Φ0002 = -0.54 ± 0.04 on the origin at a cadmium atom. From these values the atom form factors at the position of 0002 reflection were calculated as fx cd = 42.4 ± 0.5 and fx s= 13.0 ±0.2, assuming the parameter u determined by X-ray diffraction.