Measurement of effective source distribution and its importance for quantitative interpretation of STEM images

C. Dwyer, R. Erni, J. Etheridge

Research output: Contribution to journalArticle

50 Scopus citations

Abstract

We review the manner in which lens aberrations, partial spatial coherence, and partial temporal coherence affect the formation of a sub-̊A. electron probe in an aberration-corrected transmission electron microscope. Simulations are used to examine the effect of each of these factors on a STEM image. It is found that the effects of partial spatial coherence (resulting from finite effective source size) are dominant, while the effects of residual lens aberrations and partial temporal coherence produce only subtle changes from an ideal image. We also review the way in which partial spatial and temporal coherence effects are manifest in a Ronchigram. Finally, we provide a demonstration of the Ronchigram method for measuring the effective source distribution in a probe aberration-corrected 300. kV field-emission gun transmission electron microscope.

Original languageEnglish (US)
Pages (from-to)952-957
Number of pages6
JournalUltramicroscopy
Volume110
Issue number8
DOIs
StatePublished - Jul 1 2010
Externally publishedYes

Keywords

  • Coherence
  • Convergent beam electron diffraction
  • STEM

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

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