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Title: Electron ptychographic phase imaging of light elements in crystalline materials using Wigner distribution deconvolution

Recent development in fast pixelated detector technology has allowed a two dimensional diffraction pattern to be recorded at every probe position of a two dimensional raster scan in a scanning transmission electron microscope (STEM), forming an information-rich four dimensional (4D) dataset. Electron ptychography has been shown to enable efficient coherent phase imaging of weakly scattering objects from a 4D dataset recorded using a focused electron probe, which is optimised for simultaneous incoherent Z-contrast imaging and spectroscopy in STEM. Thus coherent phase contrast and incoherent Z-contrast imaging modes can be efficiently combined to provide a good sensitivity of both light and heavy elements at atomic resolution. Here, we explore the application of electron ptychography for atomic resolution imaging of strongly scattering crystalline specimens, and present experiments on imaging crystalline specimens including samples containing defects, under dynamical channelling conditions using an aberration corrected microscope. A ptychographic reconstruction method called Wigner distribution deconvolution (WDD) was implemented. Our experimental results and simulation results suggest that ptychography provides a readily interpretable phase image and great sensitivity for imaging light elements at atomic resolution in relatively thin crystalline materials.
 [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [4] ;  [5] ;  [4] ;  [6] ;  [6] ;  [1] ;  [1] ;  [7] ;  [7] ;  [3]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Foundry
  2. Univ. of Glasgow, Scotland (United Kingdom). School of Physics and Astronomy
  3. Univ. of Oxford (United Kingdom). Dept. of Materials
  4. PN Detector GmbH, Munich (Germany)
  5. PNSensor GmbH, Munich (Germany)
  6. JEOL Ltd., Tokyo (Japan)
  7. Ernst Ruska Centre (ER-C) for Microscopy and Spectroscopy with Electrons, Julich (Germany)
Publication Date:
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Published Article
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Additional Journal Information:
Journal Volume: 180; Journal Issue: C; Journal ID: ISSN 0304-3991
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; 4D-STEM; pixelated detectors; ptychography; phase retrieval; Wigner distribution deconvolution
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OSTI ID: 1417608