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 3948a 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 3948a describes:
Figure 3948b shows an example of optical interband transitions of electrons from occupied states to unoccupied states. Figure 3948b. Example of optical interband transition of electrons from occupied states to unoccupied states. Figure 3948c shows the schematic illustration of the energy level diagrams for molecular structures with different number of atoms which are single atoms, dimers, clusters and bulk materials. Splitting of the atomic energy levels occurs when the single atoms form a diatomic molecule. As more atoms join the system, the levels split further until a quasi-continuous band structure is formed in the bulk material. In other words, quantum size effects occur when the quasi-continuous band structure of a solid state system begins to break down as more atoms are included.
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