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@MISC{Strauch:897404,
      author       = {Strauch, Achim and Clausen, Alexander and Weber, Dieter and
                      Müller-Caspary, Knut},
      title        = {{H}igh-resolution 4{D} {STEM} dataset of {S}r{T}i{O}3 along
                      the [1 0 0] axis at high magnification},
      reportid     = {FZJ-2021-03770},
      year         = {2021},
      abstract     = {<p>This dataset can be used to test various analysis
                      methods for high-resolution 4D STEM, $including\&nbsp;phase$
                      contrast methods such as ptychography. Scan and diffraction
                      coordinates have been calibrated. The high scan
                      magnification allows to identify individual atoms and easily
                      distinguish them from reconstruction artifacts.</p> <p>Data
                      was acquired at a probe-corrected FEI Titan 80-300 STEM
                      operated at 300 kV. The microscope was equipped with a
                      Medipix Merlin for EM detector operated at an acquisition
                      rate for individual diffraction patterns of 1 kHz. The scan
                      size was 128 x $128\&nbsp;scan$ points and the recorded
                      diffraction patterns had a dimension of 256 x
                      $256\&nbsp;pixel.</p>$ <p>The convergence angle of the
                      incident probe was measured with a polycrystalline gold
                      specimen. Employing parallel illumination first, the (111)
                      gold diffraction ring was used to calibrate the diffraction
                      space assuming a lattice constant of gold of 0.4083 nm. With
                      the known wavelength the convergence semi-angle was
                      determined to 22.1 mrad from a Ronchigram recorded in the
                      same STEM setting as used in the actual experiment. The
                      convergence semi-angle in pixel was determined from the size
                      of the primary beam on the detector.</p> <p>The rotation and
                      handedness of the detector coordinate system with respect to
                      the scan axes was determined by minimizing the curl of the
                      first moment vector field and making sure that the
                      divergence of the field is negative at atom positions. Note
                      that, in theory, the curl of purely electrostatic fields
                      should vanish. The pixel size in the scan dimension
                      $of\&nbsp;12.7$ pm was taken from the STEM control software
                      during live processing and verified by comparison with the
                      known lattice constant of SrTiO<sub>3</sub>. The residual
                      scan distortion, that is, the translation of the diffraction
                      pattern as a whole during scanning, was not compensated for
                      since it turned out to be negligible at the
                      atomic-resolution STEM magnifications used in this
                      analysis.</p> <p>The sample thickness was approximately 25
                      nm, determined by comparing the PACBED with simulation.</p>
                      <p><strong>Parameters</strong></p> <p>Scan pixel
                      $size:\&nbsp;12.7$ pm</p> <p>Center y: 126 px</p> <p>Center
                      x: 123 px</p> <p>Convergence semi-angle: 22.13 mrad, 15.5
                      px</p> <p>Thickness: approx. 25 nm</p> <p>Affine
                      transformation of the direction of scan coordinates to
                      detector coordinates using
                      https://github.com/LiberTEM/LiberTEM/blob/master/src/libertem/corrections/coordinates.py:</p>
                      <pre>transformation $=\&nbsp;rotate_deg(88)$ @ $flip_y()$
                      $det_sy,$ $det_sx$ = $((scan_sy,$ $scan_sx)$ @
                      transformation)</pre> <p>See the included notebook for an
                      exemplary analysis.
                      $See\&nbsp;https://arxiv.org/abs/2106.13457$ for more
                      details.</p>},
      cin          = {ER-C-1},
      cid          = {I:(DE-Juel1)ER-C-1-20170209},
      pnm          = {5351 - Platform for Correlative, In Situ and Operando
                      Characterization (POF4-535) / moreSTEM - Momentum-resolved
                      Scanning Transmission Electron Microscopy (VH-NG-1317) /
                      Ptychography 4.0 - Proposal for a pilot project "Information
                      $\&$ Data Science" (ZT-I-0025)},
      pid          = {G:(DE-HGF)POF4-5351 / G:(DE-HGF)VH-NG-1317 /
                      G:(DE-HGF)ZT-I-0025},
      typ          = {PUB:(DE-HGF)33},
      doi          = {10.5281/ZENODO.5113449},
      url          = {https://juser.fz-juelich.de/record/897404},
}