Construction of the Moiré Potential. If the assumption mentioned in the previous subsection is valid, the inverse FFT (IFFT) of these extra spots will yield information on the spatial modulation of the moiré potential. It is hence interesting to reconstruct IFFT images from the FFT images by filtering in the frequency domain using the inclusive mask for the extra spots shown in Fig. , but excluding all the well-defined Bragg and center spots (for details, see Fig. ). Figure shows the thus obtained IFFT images using the FFT images shown in Fig. . We found that regardless of the twisted angles, the IFFT images exhibit a triangular lattice-like pattern. Note also that a similar pattern can be obtained even if the contrast of the respective IFFT images is inverted (Fig. ). Hence, the resulting images are not artefacts due to IFFT but will represent periodic-like 2D potential functions with comparable positive and negative amplitudes. As for the nearly commensurate cases at = 21.6° and 13.6°, the periodicities of the lattice are estimated to be ~0.6 nm and ~1.0 nm, respectively. These values are comparable to those deduced from Eq. ( ) (D = 0.66 nm and 1.08 nm for = 21.6° and 13.6°, respectively). The corresponding line profiles show distinct repeating patterns with positive and negative correlations along the three directions of the triangular lattice (Fig. ), which extends over the length scale of several to tens of nanometers (see Fig. for a wide-area IFFT image of = 21.6°). Thus, the commensurability of the MSLs is almost preserved in the IFFT image.