free electron

American  

noun

Physics.

1. an electron that is not attached to an atom or molecule and is free to respond to outside forces.

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free electron British  

noun

1. any electron that is not attached to an ion, atom, or molecule and is free to move under the influence of an applied electric or magnetic field

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Etymology

Origin of free electron

First recorded in 1905–10

Example Sentences

Experimental fusion reactors heat plasmas — free electrons and atomic nuclei — to temperatures exceeding 100 million degrees Celsius, hotter than the sun’s core.

From Washington Post

This leaves behind a searingly hot, Earth-size core composed almost entirely of naked atomic nuclei and free electrons.

From Science Magazine

Figure 1 | High-harmonic generation. a, The potential energy of free electrons is zero, but that of electrons in a solid varies because these particles are attracted to nuclei located at the potential-energy minima.

From Nature

When a particle crosses the target, it can generate tiny flashes of light and free electrons from a xenon atom.

From BBC

The binding energy of an atom or ion — the energy required to break the atom into its free electrons and a nucleus — is different in an excited metastable state from that in the ground state.

From Nature