A determination of the absolute values and signs of the 111 and 222 structure factors of silicon

The thickness fringes of a silicon wedge at the Bragg positions for 111 and 222, and at the symmetric position for hhh were observed with the electron microscope at 100 and 392 kV. The ratios of the measured fringe distances were analysed by the many-beam dynamical theory in electron diffraction assuming the theoretical values for the structure factors of orders higher than 333. As the result, the crystal structure factors are derived as F₁₁₁ = 59.87 ± 0.46 and F₂₂₂ = - 1.85 ± 0.85 at 293 °K.