# Geochronology/Cathodoluminescences

The inelastic scattering of the primary electrons in the crystal leads to the emission of secondary electrons, Auger electrons and X-rays, which in turn can scatter as well, which leads to up to 103 secondary electrons per incident electron.[1]

These secondary electrons can excite valence electrons into the conduction band when they have a kinetic energy about three times the band gap energy of the material ${\displaystyle (E_{kin}\approx 3E_{g})}$.[2]

The primary advantages to the electron microscope based technique is its spatial resolution, where the attainable resolution is on the order of a few ten nanometers,[3] while in a (scanning) transmission electron microscope, nanometer-sized features can be resolved.[4]

An optical cathodoluminescence microscope benefits from its ability to show actual visible color features directly through the eyepiece, where more recently developed systems try to combine both an optical and an electron microscope to take advantage of both these techniques.[5]

Cathodoluminescence performed in electron microscopes is also being used to study surface plasmon resonances in metallic nanoparticles.[6] Surface plasmons in metal nanoparticles can absorb and emit light, though the process is different from that in semiconductors. Similarly, cathodoluminescence has been exploited as a probe to map the local density of states of planar dielectric photonic crystals and nanostructured photonic materials.[7]