Zweck, Josef and Schwarzhuber, Felix and Poellath, Simon and Mueller-Caspary, Knut (2023) Advanced processing of differential phase contrast data: Distinction between different causes of electron phase shifts. ULTRAMICROSCOPY, 250: 113752. ISSN 0304-3991, 1879-2723
Full text not available from this repository. (Request a copy)Abstract
Differential phase contrast, in its high resolution modification also known as first moment microscopy or momentum resolved STEM [1-7], basically measures the lateral momentum transfer to the electron probe due to the beam interaction with either electrostatic and/or magnetic fields, when the probe transmits the specimen. In other words, the result of the measurement is a vector field p ($) over right arrow (x,y) which describes the lateral momentum transfer to the probe electrons. In the case of electric fields, this momentum transfer is easily converted to the electric field E ($) over right arrow (x,y) causing the deflection, and from rho =epsilon(0) del center dot E ($) over right arrow the local charge density can be calculated from the divergence of the electric field. However, from experimental data it is known that also the calculation of the vector field's curl del($) over right arrow xp ($) over right arrow in general yields non-zero results. In this paper, we use the Helmholtz decomposition (Wikipedia contributors, 2022), also known as the fundamental theorem of vector calculus, to split the measured vector fields into their curl-free and divergence-free components and to interpret the physical meaning of these components in detail. It will be shown, that non-zero curl components may be used to measure geometric phases occurring from irregularities in crystal structure such as a screw dislocation.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | LORENTZ MICROSCOPY; RECONSTRUCTION; MAGNETIZATION; DETECTOR; Helmholtz decomposition; 4DSTEM; First moment imaging; Geometric phase; Screw dislocation; Origin of divergence and curl in measured; vector fields |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Alumni or Retired Professors > Chair Professor Back > Group Josef Zweck |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 30 Jan 2024 06:51 |
| Last Modified: | 30 Jan 2024 06:51 |
| URI: | https://pred.uni-regensburg.de/id/eprint/59708 |
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