期刊
NATURE COMMUNICATIONS
卷 5, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/ncomms6653
关键词
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资金
- European Research Council under the 7th Framework Program (FP7), ERC [246791-COUNTATOMS, 278510-VORTEX]
- Flemish Government
- European Union [312483-ESTEEM2]
- DFG [RO 2057/8-1]
- Austrian Science Fund (FWF) [I543-N20]
- Austrian Science Fund (FWF) [I 543] Funding Source: researchfish
By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field- induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright- field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms.
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