Loading...
Please wait, while we are loading the content...
Similar Documents
Simulation of STEM-EELS Including Diffraction and Solid-State Effects I: Mixed Dynamic Form Factor beyond the Dipole Approximation
| Content Provider | Semantic Scholar |
|---|---|
| Author | Prange, Micah P. Oxley, Mark P. Pennycook, Stephen J. Pantelides, Sokrates T. |
| Copyright Year | 2011 |
| Abstract | Continuing advances in scanning transmission electron microscopy (STEM), including aberrationcorrection and enhanced stability, have made possible the collection of atomic resolution core-edge electron energy loss spectra (EELS). The dependence of the energy-loss spectrum on the probe position within the unit cell contains information about the spatial distribution and nature of the electronic excitations. Interpretation of such experiments, however, requires simulation to relate the strength of the EELS signal to the electronic structure and dynamics of the sample electrons. Image simulation methods used for STEM typically employ an atomic model for the inelastic scattering, and the simulated STEM-EELS images are smooth in energy-loss, missing the fine structure due to the solid-state environment of the inelastic scattering events. Hence, such simulations are usually limited to chemical maps in which the signal from a given species is integrated over an energy window, and all spectral information except atomic number is discarded. On the other hand, since EELS and x-ray absorption spectroscopy (XAS) probe the same electronic excitations, EELS experiments are frequently interpreted in terms of simulations originally developed for XAS and based on the calculation of the dynamic form factor (DFF) of the sample which is closely related to the (macroscopic) inverse dielectric function. Comparison of such simulations to measurements can be theoretically justified when the probe beam is broad so that many unit cells are interrogated simultaneously and diffraction of the probe beam by the sample can be neglected. Both of these conditions are severely violated in atomic-resolution STEM. |
| Starting Page | 808 |
| Ending Page | 809 |
| Page Count | 2 |
| File Format | PDF HTM / HTML |
| DOI | 10.1017/S1431927611004910 |
| Volume Number | 17 |
| Alternate Webpage(s) | https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1431927611004910 |
| Alternate Webpage(s) | https://doi.org/10.1017/S1431927611004910 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
