Quantification and optimization of ADF-STEM image contrast for beam-sensitive materials

Karthikeyan Gnanasekaran, Gijsbertus de With, Heiner Friedrich

Research output: Contribution to journalArticleAcademicpeer-review

6 Citations (Scopus)
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Abstract

Many functional materials are difficult to analyse by scanning transmission electron microscopy (STEM) on account of their beam sensitivity and low contrast between different phases. The problem becomes even more severe when thick specimens need to be investigated, a situation that is common for materials that are ordered from the nanometre to micrometre length scales or when performing dynamic experiments in a TEM liquid cell. Here we report a method to optimize annular dark-field (ADF) STEM imaging conditions and detector geometries for a thick and beam-sensitive low-contrast specimen using the example of a carbon nanotube/polymer nanocomposite. We carried out Monte Carlo simulations as well as quantitative ADF-STEM imaging experiments to predict and verify optimum contrast conditions. The presentedmethod is general, can be easily adapted to other beam-sensitive and/or low-contrast materials, as shown for a polymer vesicle within a TEM liquid cell, and can act as an expert guide on whether an experiment is feasible and to determine the best imaging conditions.

Original languageEnglish
Article number171838
Number of pages10
JournalRoyal Society Open Science
Volume5
Issue number5
DOIs
Publication statusPublished - 2 May 2018

Keywords

  • Beam-sensitive materials
  • Electron dose
  • Image contrast
  • Low-contrast materials
  • Monte Carlo simulations
  • Scanning transmission electron microscopy

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