The multislice algorithm has been used to simulate ADF STEM images. Examination of the evolution of the electron wavefunction as it propagates through the specimen, can provide insight into the sources of contrast in the STEM image. Plots of the wavefunction intensity as a function of position and as a convergent beam electron diffraction (CBED) pattern are two complementary views of the diffraction process. Examples from the large number of these plots that are calculated during the ADF STEM calculations will be presented.The simulated specimen consists of multiples of 47 Å (15 slices) of silicon (111). The slices are 65 Å × 66 Å(512 × 512 pixels) in size, setting the maximum included scattering angle to 95 mrad. The incident probe models a 100 keV VG-HB501 STEM at Scherzer focus with either the low resolution pole piece (Cs=3.3 mm, Δf=1100 Å, αap = 8.2 mrad) or the high resolution pole piece (Cs = 0.7 mm, Δf=510 Å, αap=12.1 mrad). The beam and specimen are aligned exactly along the (111) zone axis (no tilt).
Field validation of an actuated convergent-beam acoustic Doppler profiler for high resolution flow mapping