Spectroscopy: Absorption, Emission, and Transition Processes
1. Primary electron (probe) with sufficient energy, EP, to overcome the binding energy, EB, of the inner-shell electron, ejects the core electron
2. The primary electron is scattered in some new direction with reduced energy, EP'
3. The core electron that is removed is now free and is referred to as the secondary electron
4. The energy lost by the primary electron, EP - EP′ = EB + ES, is sensitive to the binding energy of the core electron, and by measuring this loss of energy accurately, the electronic structure of the atom/material can be probed
5. It is also possible to map the distribution of such secondary electrons as the primary electron beam is rastered along the specimen surface, and this technique forms the basis of SEM
6. Alternatively, instead of the primary electron if a photon of sufficient energy, EP = hf , is incident, the related process of photoionization occurs