Structure solution with automated electron diffraction tomography data: different instrumental approaches.

Over the past few years automated electron diffraction tomography has become an established technique for structure solution of nano-crystalline material. The intentional choice of an arbitrary tilt axis and thus, the use of nonoriented diffraction patterns (off-zone acquisition) together with fine equidistant sampling of the reciprocal space result in high quality intensity data sets. Coupling automated electron diffraction tomography with electron beam precession (Vincent & Midgley, 1994) enables sampling of intensities between the static slices of reciprocal space and therefore enhances the quality of intensity data further; relatively complex structures have been solved using 3D electron diffraction intensities extracted from automated electron diffraction tomography data. Automated electron diffraction tomography data was collected initially using a dedicated automated module. In this manuscript we demonstrate that electron diffraction data of comparable quality can be collected using manual technique that mimics the automated process. A rather difficult material, i.e. a low symmetric (triclinic) sodium tetratungstate (Na(2) W(4) O(13) ) including heavy and light scatterers, was selected for testing. In this paper we show, that all collected data sets - automatic and manual, with and without electron beam precession - were able to provide data slightly different but suitable for ab initio structure solution and refinement.