Home
Kossel-Moellenstedt Profile

The main purpose of this Kossel-Moellenstedt Profile is to perform a fit of an experimental CBED profile (Fig. 1) with a profile calculated either using the simple two-beams dynamical electron diffraction theory (with absorption) or the more complicated many-beams dynamical Bloch-waves method for accurate calculations of electron diffraction intensities.

Figure1

Figure 1 (000) and (200) CBED disks and profile.

A fit using the 2-beams mdel, that sets the specimen thickness to 157 nm, is shown in Figure 2. The Red curve and blue curves are the (200) and (000) profiles. The black curve is a measure of the goodness of fit.

Figure2

Figure 2 Thickness measurement using the 2-beams dynamical electron diffraction theory with absorption.

The same CBED profile processed with the selection of (000) center and Deviation options provide a better fit for the (200) reflection (Fig. 3a). With the more accurate many-beams theory a much better fit and a different thickness is proposed (Fig. 3b).

Figure3a Figure3b

Figure 3a 2-Beams fit with (000) center and deviation.

Figure 3b Many beams fit with (000) center and deviation.

More info here.