title: Mapping the electrostatic potential of Au nanoparticles using hybrid electron holography.
abstract: Electron holography is a powerful technique for characterizing electrostatic potentials, charge distributions, electric and magnetic fields, strain distributions and semiconductor dopant distributions with sub-nm spatial resolution. Mapping internal electrostatic and magnetic fields within nanoparticles and other low-dimensional materials by TEM requires both high spatial resolution and high phase sensitivity. Carrying out such an analysis fully quantitatively is even more challenging, since artefacts such as dynamical electron scattering may strongly affect the measurement. In-line electron holography, one of the variants of electron holography, features high phase sensitivity at high spatial frequencies, but suffers from inefficient phase recovery at low spatial frequencies. Off-axis electron holography, in contrast, can recover low spatial frequency phase information much more reliably, but is less effective in retrieving phase information at high spatial frequencies when compared to in-line holography. We investigate gold nanoparticles using hybrid electron holography at both atomic-resolution and intermediate magnification. Hybrid electron holography is a novel technique that synergistically combines off-axis and in-line electron holography, allowing the measurement of the complex wave function describing the scattered electrons with excellent signal-to-noise properties at both high and low spatial frequencies. The effect of dynamical electron scattering is minimized by beam tilt averaging.
authors.affiliation: Stuttgart Center for Electron Microscopy, Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany. Electronic address: c.ozsoy@fkf.mpg.de.
authors.forename: Cigdem
authors.initials: C
authors.lastname: Ozsoy-Keskinbora
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: Chris B
authors.initials: CB
authors.lastname: Boothroyd
authors.affiliation: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: Rafal E
authors.initials: RE
authors.lastname: Dunin-Borkowski
authors.affiliation: Stuttgart Center for Electron Microscopy, Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany.
authors.forename: Peter A
authors.initials: PA
authors.lastname: van Aken
authors.affiliation: Structure Research & Electron Microscopy group, Department of Physics, Humboldt University of Berlin, Newtonstraße 15, 12489 Berlin, Germany.
authors.forename: Christoph T
authors.initials: CT
authors.lastname: Koch
keywords: High resolution phase retrieval; Hybrid electron holography; In-line electron holography; Mean inner potential; Nanoparticles; Off-axis electron holography