Measurement of chromatic aberration in STEM and SCEM by coherent convergent beam electron diffraction

Zheng, Changlin; Etheridge, Joanne

doi:10.1016/j.ultramic.2012.10.002

Cited by 13 publications

(10 citation statements)

References 47 publications

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“…Finally, the chromatic aberration of the post-specimen lenses will cause a chromatical defocus spread of the beam spots. The chromatic defocus of inelastically scattered electrons with energy loss of carbon K -edge (Δ E = 285 eV) is Δ f C = C c Δ E / E 0 ≈ 3.5 μ m for E 0 = 200 keV and typical chromatic aberration coefficient C C = 2.5 mm 35 , in the same order to the defocus applied in SCED. In SCED, we use on-axis illumination therefore the chromatically defocused disks are concentric to the diffraction spots 36 , thus do not influence the accuracy to locate the Bragg spots.…”

Section: Resultsmentioning

confidence: 97%

Seeing structural evolution of organic molecular nano-crystallites using 4D scanning confocal electron diffraction (4D-SCED)

Harreiß

Ophus

et al. 2022

Nat Commun

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Direct observation of organic molecular nanocrystals and their evolution using electron microscopy is extremely challenging, due to their radiation sensitivity and complex structure. Here, we introduce 4D-scanning confocal electron diffraction (4D-SCED), which enables direct in situ observation of bulk heterojunction (BHJ) thin films. 4D-SCED combines confocal electron optic setup with a pixelated detector to record focused spot-like diffraction patterns with high angular resolution, using an order of magnitude lower dose than previous methods. We apply it to study an active layer in organic solar cells, namely DRCN5T:PC71BM BHJ thin films. Structural details of DRCN5T nano-crystallites oriented both in- and out-of-plane are imaged at ~5 nm resolution and dose budget of ~5 e−/Å2. We use in situ annealing to observe the growth of the donor crystals, evolution of the crystal orientation, and progressive enrichment of PC71BM at interfaces. This highly dose-efficient method opens more possibilities for studying beam sensitive soft materials.

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Section: Resultsmentioning

confidence: 97%

Seeing structural evolution of organic molecular nano-crystallites using 4D scanning confocal electron diffraction (4D-SCED)

Harreiß

Ophus

et al. 2022

Nat Commun

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“…This has important ramifications for inelastic scattering measurements with electron spectroscopy, which the authors demonstrate with measurements of the probe after scattering from a plasmon. The same group also demonstrated direct measurements of chromatic aberration coefficients in STEM in Zheng & Etheridge (2013). Another follow-up paper by Zheng et al (2014) introduced the concept of "off-axis" SCEM, which is shown in Figure 11e.…”

Section: Real-space 4d-stemmentioning

confidence: 96%

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

2019

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Scanning transmission electron microscopy (STEM) is widely used for imaging, diffraction, and spectroscopy of materials down to atomic resolution. Recent advances in detector technology and computational methods have enabled many experiments that record a full image of the STEM probe for many probe positions, either in diffraction space or real space. In this paper, we review the use of these four-dimensional STEM experiments for virtual diffraction imaging, phase, orientation and strain mapping, measurements of medium-range order, thickness and tilt of samples, and phase contrast imaging methods, including differential phase contrast, ptychography, and others.

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“…The relativistic chromatic aberration coefficient of our instrument was measured by analyzing, for the same electron-optical configuration used for ADF, Ronchigrams of aluminium acquired at different beam energies, giving a relativistic value of C c ¼ 2:4860:05 mm. 21 Together with the beam's energy spread in the same electron-optical configuration, DE ¼ 0:8760:03 eV, which was measured using the instrument's spectrometer, the focal standard deviation is then calculated to be r f ¼ 3:160:2 nm.…”

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confidence: 99%

Sub-0.1 nm-resolution quantitative scanning transmission electron microscopy without adjustable parameters

Dwyer

Maunders

Zheng

et al. 2012

Applied Physics Letters

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Atomic-resolution imaging in the scanning transmission electron microscope (STEM) constitutes a powerful tool for nanostructure characterization. Here, we demonstrate the quantitative interpretation of atomic-resolution high-angle annular dark-field (ADF) STEM images using an approach that does not rely on adjustable parameters. We measure independently the instrumental parameters that affect sub-0.1 nm-resolution ADF images, quantify their individual and collective contributions to the image intensity, and show that knowledge of these parameters enables a quantitative interpretation of the absolute intensity and contrast across all accessible spatial frequencies. The analysis also provides a method for the in-situ measurement of the STEM’s effective source distribution.

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Measurement of chromatic aberration in STEM and SCEM by coherent convergent beam electron diffraction

Cited by 13 publications

References 47 publications

Seeing structural evolution of organic molecular nano-crystallites using 4D scanning confocal electron diffraction (4D-SCED)

Seeing structural evolution of organic molecular nano-crystallites using 4D scanning confocal electron diffraction (4D-SCED)

Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond

Sub-0.1 nm-resolution quantitative scanning transmission electron microscopy without adjustable parameters

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