Sources of error in Debye–Waller-effect measurements relevant to studies of photoinduced structural dynamics

Elisah J. VandenBussche, David J. Flannigan

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

We identify and quantify several practical effects likely to be present in both static and ultrafast electron-scattering experiments that may interfere with the Debye–Waller (DW) effect. Using 120-nm thick, small-grained, polycrystalline aluminum foils as a test system, we illustrate the impact of specimen tilting, in-plane translation, and changes in z height on Debye–Scherrer-ring intensities. We find that tilting by less than one degree can result in statistically-significant changes in diffracted-beam intensities for large specimen regions containing > 105 nanocrystalline grains. We demonstrate that, in addition to effective changes in the field of view with tilting, slight texturing of the film can result in deviations from expected DW-effect behavior. Further, we find that in-plane translations of as little as 20 nm also produce statistically-significant intensity changes, while normalization to total image counts eliminates such effects arising from changes in z height. The results indicate that the use of polycrystalline films in ultrafast electron-scattering experiments can greatly reduce the negative impacts of these effects as compared to single-crystal specimens, though it does not entirely eliminate them. Thus, it is important to account for such effects when studying thin-foil specimens having relatively short reciprocal-lattice rods.

Original languageEnglish (US)
Pages (from-to)111-120
Number of pages10
JournalUltramicroscopy
Volume196
DOIs
StatePublished - Jan 2019

Keywords

  • Debye–Waller effect
  • In situ electron microscopy
  • Transmission electron microscopy
  • Ultrafast electron diffraction
  • Ultrafast electron microscopy
  • Ultrafast structural dynamics

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

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