Fig. -5j shows a series of 20-millisecond video frames (50 fps) of 2 partially exposed to vacuum. It is partially buried in an electron-rich and conductive CNT substrate (»10 3 more conductive than aC) that protects the specimen from radiolysis . The cube was structurally stable over 27 s, although it tumbled a few times possibly on the fishhook serving as a pivot (Fig. ) because of stochastic motions of the CNT substrate . The slightly blurred image of individual atoms reflects atomic vibration during the 20-millisecond imaging period (Fig. ). In these figures, we can identify three edges, two faces, and three corners, from which we determined the geometrical orientation of the cuboid along the electron beam (See Supplementary Note 3). The ZC structural model of Cs58Pb64B240 54-in Fig. is seen from the same direction. In this model, the surface is fully Br passivated except that the edge Br (#1 in Fig. ) is replaced by MLA and not seen. The TEM image and the model share several common features: eight parallel arrays of heavy atoms as counted from the edge in the center (line 1 shown in Fig. , 5k), rhombic lattice images due to Pb and Br and, importantly, the lack of Cs atoms in all edges (compare Fig. and). Note that the Cs atoms should have been seen clearly if they were present on the edges. This provides an atomistic proof of the lack of surface defects that was suggested from the excellent PLQY and high stability. A 0.6-0.7 nm Pb-Pb distance determined for the rhombic lattice image agrees with the »0.6 nm distance in a bulk crystal of CsPbBr3, considering the lattice vibration and instrumental resolution of 0.08 nm (see Supplementary Information for details). Fast Fourier transform analysis of the whole area of the QD image indicated that the specimen is structurally homogeneous (Figures and). Detailed interpretation of the simulation can be found in the Supplementary Note 4.