Kinematic and dynamical CBED for solving thin organic films at low temperature; experimental tests with anthracene

J. S. Wu, John Spence

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Low-dose, low-temperature kinematic and dynamical convergent-beam electron diffraction (CBED) patterns from thin organic crystalline films have been used for the measurement of structure-factor amplitudes and phases. Kinematic conditions are identified by the observation of uniform intensity within the CBED discs and used to determine structure-factor magnitudes. CBED patterns from thicker regions affected by multiple scattering give structure-factor signs, which are varied for best fit. The use of a small probe (and the Kohler SAD mode) minimizes bending artifacts. A new method of thickness determination is evaluated. The approach is tested using experimental data from the centrosymmetric anthracene structure, the results compared with direct methods, and a potential map derived from experimental data. The faint peaks due to H-atom positions may be distinguished. Key issues influencing the validity of the method such as the appropriate dimension of the structure-factor matrix, sample thickness and crystal orientation are discussed.

Original languageEnglish (US)
Pages (from-to)580-589
Number of pages10
JournalActa Crystallographica Section A: Foundations of Crystallography
Volume58
Issue number6
DOIs
StatePublished - Nov 2002

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Anthracene
anthracene
Biomechanical Phenomena
Electron diffraction
Kinematics
kinematics
electron diffraction
Electrons
Diffraction patterns
Temperature
diffraction patterns
Multiple scattering
Crystal orientation
Artifacts
Observation
Crystalline materials
artifacts
Atoms
dosage
probes

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Structural Biology

Cite this

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