title: Automatic software correction of residual aberrations in reconstructed HRTEM exit waves of crystalline samples.
abstract: We develop an automatic and objective method to measure and correct residual aberrations in atomic-resolution HRTEM complex exit waves for crystalline samples aligned along a low-index zone axis. Our method uses the approximate rotational point symmetry of a column of atoms or single atom to iteratively calculate a best-fit numerical phase plate for this symmetry condition, and does not require information about the sample thickness or precise structure. We apply our method to two experimental focal series reconstructions, imaging a β-Si3N4wedge with O and N doping, and a single-layer graphene grain boundary. We use peak and lattice fitting to evaluate the precision of the corrected exit waves. We also apply our method to the exit wave of a Si wedge retrieved by off-axis electron holography. In all cases, the software correction of the residual aberration function improves the accuracy of the measured exit waves.
authors.affiliation: National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, USA.
authors.forename: Colin
authors.identifier: 0000-0003-2348-8558
authors.initials: C
authors.lastname: Ophus
authors.affiliation: Department of Physics, University of California Berkeley, 366 LeConte Hall, Berkeley, MC 7300 USA ; Materials Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, USA.
authors.forename: Haider I
authors.initials: HI
authors.lastname: Rasool
authors.affiliation: Corrected Electron Optical Systems GmbH, Englerstrasse 28, 69126 Heidelberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Linck
authors.affiliation: Department of Physics, University of California Berkeley, 366 LeConte Hall, Berkeley, MC 7300 USA ; Materials Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Zettl
authors.affiliation: National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, USA.
authors.forename: Jim
authors.initials: J
authors.lastname: Ciston
keywords: Aberration correction; Atomic resolution HRTEM; Inline holography; Off-axis holography; Wavefront sensing