Extended Data Fig. 4: Off-axis EELS measurements.
a, A schematic of the diffraction plane and EELS aperture placement. The colormap illustrates the diffraction plane viewed from \([11\bar{2}]\) zone axis, with 60 kV beam energy and 35 mrad convergence semi-angle. The diffraction spot size (35 mrad) is larger than the distance between adjacent spots, so they partially overlap. The green circle marks the position of the aperture, which is displaced away from the central spot. b, The EELS line profile acquired with off-axis geometry. Main spectral features are consistent with those acquired with on-axis geometry (Fig. 2b, Extended Data Fig. 3). c, Corresponding simulation result. d, EELS maps at selected energies. One of the interfacial modes has a better contrast than the on-axis result. e–h, same as a–d, but the beam is travelling along \([1\bar{1}0]\) direction.
