Fig. 1: Low-dose dislocation analysis by SED.

a, Illustration of the distortion of planes due to edge, mixed and screw dislocations, with no distortion for planes corresponding to diffraction vectors g_hkl at the invisibility criterion (g_hkl ∙ B = 0). b, Schematic of an edge dislocation core in a p-terphenyl crystal with Burgers vector B = [010]. The blue parallelograms represent molecules in a plane below those in orange. A black rectangle or line marks the a–b plane of the p-terphenyl lattice in the plane below (blue) the dislocation core (⊥). c, A bend contour appears where the sample curvature brings planes (hkl) to the exact Bragg condition, with displacements in the bend contour due to abrupt changes in the orientation of planes around the dislocation core, marked by the dislocation line u. The electron beam is scanned in (x, y), enabling the reconstruction of bend contours from multiple diffraction vectors g_hkl in parallel from two-dimensional diffraction patterns (k_x, k_y) recorded at each probe position to give a four-dimensional dataset (x, y, k_x, k_y). The sample bending is exaggerated for visual effect. The axes are shown as in an experiment, with the scan and diffraction cameras not generally aligned, requiring rotation calibration (Methods).