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

Brighter soft X-ray free electron lasers are available which would enable even clearer images with less grainy "noise."

From Science Daily • May 24, 2024

Although soft X-ray free electron lasers have previously been used to study smaller viruses and bacteria, mammalian cells were too big to be studied this way.

From Science Daily • May 24, 2024

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 • Sep. 18, 2023

Such a detached proton won’t remain alone forever when attractive electrons are around; it will capture a free electron, becoming a neutral hydrogen once more.

From Textbooks • Oct. 13, 2016

Charley danced and flicked around the cabin like a free electron with a careless disregard for traffic regulations and public safety.

From Master of the Moondog by Mullen, Stanley