Electron scattering
| Electron 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/inelastic-ally 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.
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| Electron ( e− , β− ) |
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| 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 occurs when electrons are deviated 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.
The application of electron scattering is such that it can be used as a high resolution microscope 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:
The likelihood of an electron scattering and the proliferance of the scattering is a probability function of the specimen thickness to the mean free path.
The principle of the electron was first theorised in the period of 1838-1851 by a natural philosopher by the name of Richard Laming who speculated the existence of sub-atomic, unit charged particles; he also pictured the atom as being an 'electrosphere' of concentric shells of electrical particles surrounding a material core.
It is generally accepted that J. J. Thomson first discovered the electron in 1897, although other notable members in the development in charged particle theory are George Johnstone Stoney (who coined the term "electron"), Emil Wiechert (who was first to publish his independent discovery of the electron), Walter Kaufmann, Pieter Zeeman and Hendrik Lorentz.
Compton scattering was first observed at Washington University in 1923 by Arthur Compton who earned the 1927 Nobel Prize in Physics for the discovery; his graduate student Y. H. Woo who further verified the results is also of mention. Compton scattering is usually cited in reference to the interaction involving the electrons of an atom, however nuclear Compton scattering does exist.
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Wikipedia