| Institution: | 1. JEOL (Beijing) Co., Ltd., Shanghai Branch, Shanghai, 201210 China;2. School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210 China
Shanghai Key Laboratory of High-Resolution Electron Microscopy, ShanghaiTech University, Shanghai, 201210 China;3. School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210 China;4. FH electron optics, Kita, Kunitachi, Tokyo, 186-0001 Japan |
| Abstract: | It has become very important to study and find optimal conditions for imaging electron-beam (e-beam) sensitive materials in scanning transmission electron microscopy under low electron-dose with high signal-to-noise ratio (SNR). Convergence and collection angles and electron-probe current are essential parameters. However, these parameters have rarely been discussed in a systematic way. In this paper, the illumination and collection conditions are optimized according to the resolution requirement of different materials by adjusting the condenser and intermediate lenses in a commercial transmission electron microscope. To demonstrate the significance of optimizing these parameters, two examples, zeolite MFI and metal–organic framework (MOF) MIL-101, are taken among the sensitive materials, with the most important electron incidences along the 010] and <110> directions, respectively. High SNR atomic resolution images of MFI are obtained with e-beam current as low as 0.50 pA, reaching information transfer for reflection up to 18 0 2 corresponding to d-spacing of 0.11 nm, close to the resolution limit of 0.098 nm from resolvable diffraction limit. MOF MIL-101 is characterized under an even lower e-beam 0.2 pA to avoid severe beam damage. High-quality annular dark and bright field images are obtained, which proves the wide applicability of this method on more e-beam sensitive materials. |
