Measurement of Absorption Parameters of Copper for 500 kV Electrons

Absorption parameters of copper for 500 kV electrons are measured by means of the dynamical theory of electron diffraction of two-beam approximation by analysing the images of thickness fringes photographed with the single-beam and the two-beam methods. A bent wedge-shaped crystal is observed in the two-beam image using both the primary and the reflected beams with a large aperture as well as in the bright-field and the dark-field images using a small aperture. The following values of the absorption parameters have been obtained ξ220/ξ'0=0.070±0.007 and ξ220/ξ'220=0.051±0.003 at a temperature of 300 K, and ξ220/ξ'0=0.053±0.004 and ξ220/ξ'220=0.042±0.003 at a temperature of 200 K. Many-beam effects on the images of thickness contour are considered.