Electron Energy Loss Spectroscopy Solutions for Nanoscale Materials Science Problems
In the Transmission Electron Microscope (TEM), an incident electron suffers both elastic and inelastic scattering by the solid state thin sample that is being characterised. In the event of inelastic scattering, the incident electron gives a part of its energy to the electrons in the sample. The amo...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2009 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/662847 |
| Acceso en línea: | http://hdl.handle.net/10803/662847 |
| Access Level: | acceso abierto |
| Palabra clave: | Espectroscòpia de pèrdua d'energia d'electrons Espectroscopía por pérdidas de energía de electrones Electron energy loss spectroscopy Nanotecnologia Nanotecnología Nanotechnology Ciències Experimentals i Matemàtiques 62 |
| Sumario: | In the Transmission Electron Microscope (TEM), an incident electron suffers both elastic and inelastic scattering by the solid state thin sample that is being characterised. In the event of inelastic scattering, the incident electron gives a part of its energy to the electrons in the sample. The amount of lost energy can then be measured by a magnetic filter at the end of the column, and a plot displaying how many electrons have lost what amount of energy will give us an Electron Energy Loss (EEL) Spectrum. Thus, in an EEL Spectrum the ordinate axis corresponds to the number of electrons, or counts, and the abscise corresponds to the Energy Loss. Notice that most electrons shall not suffer any inelastic scattering whatsoever. As a consequence, the greatest contribution to the spectrum is due to these electrons having lost zero energy, giving rise to the so-called zero loss peak (ZLP). As for those electrons having lost a certain amount of energy, they may lose it to ionization of specimen electrons, transitions from occupied core states to unoccupied core states or to conduction band states, to interband transitions or excitations of collective vibrations of conduction band electrons. Incident electrons carry a given momentum, and it is worth keeping in mind that in an inelastic scattering event not only energy, but also momentum, may be transferred. In fact, this is the reason why it is not straightforward to compare EELS results with those obtained by means of optic spectroscopies. EELS detectors can provide an energy resolution down to the order of the 0.1 eV. In addition, incident electrons can be tuned by TEM optics, making it possible to get spectroscopic information from an extremely constrained area, and to combine EEL Spectroscopy with TEM imaging. |
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