Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix
Figure 3949a shows an energy-level diagram of a solid with core-level excitation and electron emission processes at solid surface. This energy-level diagram provides a detailed view of the electronic structure of a solid, highlighting the core levels (K- and L-shells), the valence band, and critical energy levels such as the Fermi level (EF) and the vacuum level (Evac). The diagram illustrates the primary processes of electron excitation, where external energy sources, such as X-rays or incident electrons, can eject electrons from inner core levels (K and L). This excitation can lead to various secondary emission processes, including the emission of secondary electrons, photons (light and X-rays), and Auger electrons. The Fermi level (EF) is shown as the energy level at which electrons are in equilibrium at absolute zero temperature, representing the dividing line between occupied and unoccupied electronic states. The vacuum level (Evac) indicates the energy threshold an electron must exceed to escape the solid into the vacuum. The valence band, represented as a shaded region, contains delocalized states where electrons are free to move throughout the material, playing a crucial role in its conductive properties.
In details, the diagram in Figure 3949a describes:
Although the fine structures of core loss spectra give information of the unoccupied density of states, the main application of EELS had still been the elemental quantification until the end of the 1980s mainly because the lack of modeling methods of the ELNES spectra. ELNES analysis has now been commonly applied since theoretical ELNES calculations become easier. Figure 3949b shows an example of optical interband transitions of electrons from occupied states to unoccupied states. Figure 3949b. Example of optical interband transition of electrons from occupied states to unoccupied states.
|