Inelastic Scattering in Electron Backscatter Diffraction and Electron Channeling Contrast Imaging

Mendis, Budhika G.; Barthel, Juri; Findlay, Scott D.; Allen, L. J.

doi:10.1017/s1431927620024605

Cited by 4 publications

(8 citation statements)

References 53 publications

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“…For the case of EBSD patterns, the Kikuchi patterns can be well described by diffraction effects from point emitters of backscattered electrons which are localised at atomic positions 3 . Key assumptions concerning the treatment of inelastic scattering and the resulting electron energy spectrum relevant for the Bloch wave simulations 42 have been confirmed by the analysis of plasmon and phonon scattering in a multi‐slice treatment of EBSD Kikuchi patterns 43,44 . The interpretation of Bloch wave solutions in terms of quantum trajectories 45,46 can potentially provide a framework for the consistent combination of classical Monte Carlo trajectory simulations with the interference effects of electron diffraction.…”

Section: Introductionmentioning

confidence: 88%

“…In terms of the relevant energy spectrum, the trajectories of the backscattered electrons in the tilted EBSD geometry (sample tilts are often near 70 degrees relative to the primary beam) emphasise the conservation of diffraction contrast only for relatively low‐energy losses relative to the primary beam energy, whereas diffraction contrast largely disappears for increasing energy losses. 42,44,92–94 …”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…This leads to a loss of the CPE Kikuchi features, which are based on standing wave formation by interference. Incoherent scattering can explain the loss of Kikuchi pattern contrast in connection with plasmon scattering, which is not localised at specific points in the unit cell 44,93,94 . The loss of CPE Kikuchi contrast observed after inelastic scattering in energy‐resolved experiments can be simulated by a phenomenological reduction of the interference terms in the Bloch wave model 94 …”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…3 Key assumptions concerning the treatment of inelastic scattering and the resulting electron energy spectrum relevant for the Bloch wave simulations 42 have been confirmed by the analysis of plasmon and phonon scattering in a multi-slice treatment of EBSD Kikuchi patterns. 43,44 The interpretation of Bloch wave solutions in terms of quantum trajectories 45,46 can potentially provide a framework for the consistent combination of classical Monte Carlo trajectory simulations with the interference effects of electron diffraction. Because multi-slice treatments of EBSD Kikuchi patterns 44,47 are not limited to perfect crystals, they can also be a powerful tool to study the specific influence of defects in the observed diffraction patterns.…”

Section: Introductionmentioning

confidence: 99%

“…43,44 The interpretation of Bloch wave solutions in terms of quantum trajectories 45,46 can potentially provide a framework for the consistent combination of classical Monte Carlo trajectory simulations with the interference effects of electron diffraction. Because multi-slice treatments of EBSD Kikuchi patterns 44,47 are not limited to perfect crystals, they can also be a powerful tool to study the specific influence of defects in the observed diffraction patterns.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Kikuchi pattern simulations of backscattered and transmitted electrons

Winkelmann

Nolze

Cios

et al. 2021

Journal of Microscopy

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We discuss a refined simulation approach which treats Kikuchi diffraction patterns in electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). The model considers the result of two combined mechanisms: (a) the dynamical diffraction of electrons emitted coherently from point sources in a crystal and (b) diffraction effects on incoherent diffuse intensity distributions. Using suitable parameter settings, the refined simulation model allows to reproduce various thickness‐ and energy‐dependent features which are observed in experimental Kikuchi diffraction patterns. Excess‐deficiency features are treated by the effect of gradients in the incoherent background intensity. Based on the analytical two‐beam approximation to dynamical electron diffraction, a phenomenological model of excess‐deficiency features is derived, which can be used for pattern matching applications. The model allows to approximate the effect of the incident beam geometry as a correction signal for template patterns which can be reprojected from pre‐calculated reference data. As an application, we find that the accuracy of fitted projection centre coordinates in EBSD and TKD can be affected by changes in the order of 10−3–10−2 if excess‐deficiency features are not considered in the theoretical model underlying a best‐fit pattern matching approach. Correspondingly, the absolute accuracy of simulation‐based EBSD strain determination can suffer from biases of a similar order of magnitude if excess‐deficiency effects are neglected in the simulation model.

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Section: Introductionmentioning

confidence: 88%

Section: Theoretical Backgroundmentioning

confidence: 99%

Section: Theoretical Backgroundmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Kikuchi pattern simulations of backscattered and transmitted electrons

Winkelmann

Nolze

Cios

et al. 2021

Journal of Microscopy

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A “Phase Scrambling” Algorithm for Parallel Multislice Simulation of Multiple Phonon and Plasmon Scattering Configurations

Mendis

2023

Microscopy and Microanalysis

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Multislice simulations of 4D scanning transmission electron microscopy (4D STEM) data are computationally demanding due to the large number of STEM probe positions that must be calculated. For accurate analysis, inelastic scattering from phonons and plasmons must also be included. However, current frozen phonon and Monte Carlo plasmon techniques require a separate calculation for each different phonon/plasmon configuration, and are therefore not suitable for scaling up to 4D STEM. Here a phase scrambling algorithm (PSA) is proposed, which treats all phonon/plasmon configurations simultaneously. A random phase is introduced to maintain incoherence between the different inelastic scattering events; this is the phase scrambling part of the algorithm. While for most applications, a few tens of frozen phonon iterations are sufficient for convergence, in the case of plasmon scattering as many as tens of thousands of iterations may be required. A PSA is statistically more representative of inelastic scattering, and achieves significant savings in computation time for plasmons. The increase in speed is a pre-requisite for 4D STEM inelastic scattering simulations.

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Modelling dynamical 3D electron diffraction intensities. II. The role of inelastic scattering

Mendis

2024

Acta Cryst Sect A

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The strong interaction of high-energy electrons with a crystal results in both dynamical elastic scattering and inelastic events, particularly phonon and plasmon excitation, which have relatively large cross sections. For accurate crystal structure refinement it is therefore important to uncover the impact of inelastic scattering on the Bragg beam intensities. Here a combined Bloch wave–Monte Carlo method is used to simulate phonon and plasmon scattering in crystals. The simulated thermal and plasmon diffuse scattering are consistent with experimental results. The simulations also confirm the empirical observation of a weaker unscattered beam intensity with increasing energy loss in the low-loss regime, while the Bragg-diffracted beam intensities do not change significantly. The beam intensities include the diffuse scattered background and have been normalized to adjust for the inelastic scattering cross section. It is speculated that the random azimuthal scattering angle during inelastic events transfers part of the unscattered beam intensity to the inner Bragg reflections. Inelastic scattering should not significantly influence crystal structure refinement, provided there are no artefacts from any background subtraction, since the relative intensity of the diffracted beams (which includes the diffuse scattering) remains approximately constant in the low energy loss regime.

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Inelastic Scattering in Electron Backscatter Diffraction and Electron Channeling Contrast Imaging

Abstract: Abstract

Cited by 4 publications

References 53 publications

Kikuchi pattern simulations of backscattered and transmitted electrons

Kikuchi pattern simulations of backscattered and transmitted electrons

A “Phase Scrambling” Algorithm for Parallel Multislice Simulation of Multiple Phonon and Plasmon Scattering Configurations

Modelling dynamical 3D electron diffraction intensities. II. The role of inelastic scattering

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