Electron scattering
Electron scattering occurs when electrons are displaced from their original trajectory. This is due to the electrostatic forces within matter interaction or, if an external magnetic field is present, the electron may be deflected by the Lorentz force. This scattering typically happens with solids such as metals, semiconductors and insulators; and is a limiting factor in integrated circuits and transistors.
| Types of Scattering | |
|---|---|
Pictorial description of how an electron beam may interact with a sample with nucleus N, and electron cloud of electron shells K,L,M. Showing transmitted electrons and elastic/inelastically scattered electrons. SE is a Secondary Electron ejected by the beam electron, emitting a characteristic photon (X-Ray) γ. BSE is a Back-Scattered Electron, an electron which is scattered backwards instead of being transmitted through the sample. | |
| Electron ( e− , β− ) | |
| Particle | Electron |
| Mass | 9.10938291(40)×10−31 kg 5.4857990946(22)×10−4 u [1822.8884845(14)]−1 u 0.510998928(11) MeV/c2 |
| Electric Charge | −1 e −1.602176565(35)×10−19 C −4.80320451(10)×10−10 esu |
| Magnetic Moment | −1.00115965218076(27) μB |
| Spin | 1⁄2 |
| Scattering | |
| Forces/Effects | Lorentz force, Electrostatic force, Gravitation, Weak interaction |
| Measures | Charge, Current |
| Categories | Elastic collision, Inelastic collision, High energy, Low energy |
| Interactions | e− — e− e− — γ e− — e+ e− — p e− — n e− — Nuclei |
| Types | Compton scattering Møller scattering Mott scattering Bhabha scattering Bremsstrahlung Deep inelastic scattering Synchrotron emission Thomson scattering |
Electron scattering has many applications ranging from the use of swift electron in electron microscopes to very high energies for hadronic systems, that allows the measurement of the distribution of charges for nucleons and nuclear structure. The scattering of electrons has allowed us to understand that protons and neutrons are made up of the smaller elementary subatomic particles called quarks.
Electrons may be scattered through a solid in several ways:
- Not at all: no electron scattering occurs at all and the beam passes straight through.
- Single scattering: when an electron is scattered just once.
- Plural scattering: when electron(s) scatter several times.
- Multiple scattering: when electron(s) scatter many times over.
The likelihood of an electron scattering and the degree of the scattering is a probability function of the specimen thickness and the mean free path.