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

In a free electron laser, a linear accelerator, or linac, shoots a beam of high-energy electrons into a string of complex magnets called undulators.

From Science Magazine

As minerals sit in the ground, they are exposed to environmental radiation and accumulate free electrons.

From New York Times

For example, metals are shiny because they contain lots of free electrons that can absorb light and then reemit most of it, making their surfaces gleam.

From Scientific American

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