The critical dose of {431} Bragg plane is 11.4 ± 3.0 e -Å -2 as the threshold to which the ZIF-8 pore aperture stays intact. In HRTEM imaging beyond this critical dose, the crystalline porous structure cannot be resolved. For example, the phase-contrast TEM image of ZIF-8 in fig. (a) (left inset) was acquired with a cumulative dose larger than 11 e -Å -2 . Hence, the {431} Bragg plane is already affected by the electron beam and is absent in the corresponding FFT pattern. Detailed analyses show that the critical dose for {400} Bragg plane is 4.0 ± 1.2 e -Å -2 . The {222} Bragg plane, which represents the stability of the body diagonal of the cubic ZIF-8 (see fig. ), experiences contraction when the critical dose exceeds 12.6 ± 5.6 e -Å -2 . The {200} Bragg plane starts shrinking as the critical dose exceeds 17.5 ± 7.4 e -Å -2 , followed by the {211} Bragg plane with a critical dose of 24.0 ± 6.4 e -Å -2 . At last, the {110} Bragg plane undergoes rapid shrinkage or displacement beyond the critical dose of 35.6 ± 8.4 e -Å -2 .