THE DIRECT OBSERVATION AND UTILIZATION OF DYNAMIC PHASE IN CONVERGENT-BEAM ELECTRON-DIFFRACTION

It is shown experimentally that significant structural phase information can be obtained by direct interference in the diffraction plane. Specifically, the intensity distributions of the {100} discs in the convergent-beam pattern of alpha(low)-quartz form, to within experimental accuracy, a hexagonal array about the c axis, but with suitable electron optics these beams can be made to interfere and the regions of overlap then form a trigonal array about the same axis. The relative phases and intensities thus determined are, of course, dynamical.