photon
noun
pho·ton ˈfō-ˌtän 
1
: a quantum of electromagnetic radiation
Should a substance happen to have a lot of electrons in a higher level, and a lower level is mostly empty …, then a photon can cause an electron to transfer from a higher state to a lower one. This change releases energy and creates a new photon, in addition to the one which caused the transfer. This photon can in turn induce more electrons to fall to a lower state.
Robert Gilmore
Robert Gilmore2
dated : troland
photonic
fō-ˈtä-nik
adjective 
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Science and the Photon
It was Albert Einstein who first theorized that the energy in a light beam exists in small bits or particles, and scientists today know that light sometimes behaves like a wave (somewhat like sound or water) and sometimes like a stream of particles. The energies of photons range from high-energy gamma rays and X-rays down to low-energy infrared and radio waves, though all travel at the same speed. The amazing power of lasers is the result of a concentration of photons that have been made to travel together in order to hit their target at the same time.
Example Sentences
Recent Examples on the Web Implementing this in practice is a bit more complex, and the researchers used different photon properties than just the number of photons. Chris Lee, Ars Technica, 15 Apr. 2022 Think of it as gently guiding a line of drunk photons around patrons at a bar, as opposed to letting the patrons smack each photon on the head and send it reeling off in a new direction, only to be swatted away again. Chris Lee, Ars Technica, 18 Apr. 2022 Using photon detectors, doctors can track how technetium-99m moves throughout the body and create images of the heart, brain, lungs and other critical organs to help diagnose diseases including cancer. Artemis Spyrou, The Conversation, 24 May 2022 To study loss, the scientists first set up an experiment where a non-important photon was bounced into a position where it would intentionally be lost in the interference noise. Caroline Delbert, Popular Mechanics, 29 Apr. 2022 Any photon that emits in the wrong direction gets reflected to either strike the thermophotovoltaic device or be absorbed by the heating element, thus helping maintain its high temperature. John Timmer, Ars Technica, 14 Apr. 2022 First five-photon entanglement demonstrated by Jian-Wei Pan's group at the University of Science and Technology in China. Gil Press, Forbes, 14 Apr. 2022 And just like an electron, the antiproton can shift between orbitals by absorbing or emitting a photon. John Timmer, Ars Technica, 16 Mar. 2022 The electron can hop up to a higher-energy state by absorbing a photon whose frequency makes up the difference between the two states’ natural frequencies. Quanta Magazine, 26 Jan. 2022 See More
Chris Lee, Ars Technica, 15 Apr. 2022 Think of it as gently guiding a line of drunk photons around patrons at a bar, as opposed to letting the patrons smack each photon on the head and send it reeling off in a new direction, only to be swatted away again. Chris Lee, Ars Technica, 18 Apr. 2022 Using photon detectors, doctors can track how technetium-99m moves throughout the body and create images of the heart, brain, lungs and other critical organs to help diagnose diseases including cancer. Artemis Spyrou, The Conversation, 24 May 2022 To study loss, the scientists first set up an experiment where a non-important photon was bounced into a position where it would intentionally be lost in the interference noise. Caroline Delbert, Popular Mechanics, 29 Apr. 2022 Any photon that emits in the wrong direction gets reflected to either strike the thermophotovoltaic device or be absorbed by the heating element, thus helping maintain its high temperature. John Timmer, Ars Technica, 14 Apr. 2022 First five-photon entanglement demonstrated by Jian-Wei Pan's group at the University of Science and Technology in China. Gil Press, Forbes, 14 Apr. 2022 And just like an electron, the antiproton can shift between orbitals by absorbing or emitting a photon. John Timmer, Ars Technica, 16 Mar. 2022 The electron can hop up to a higher-energy state by absorbing a photon whose frequency makes up the difference between the two states’ natural frequencies. Quanta Magazine, 26 Jan. 2022 See More Word History
Etymology
phot- + -on entry 2
First Known Use
1916, in the meaning defined at sense 2
Kids Definition
photon
noun
pho·ton ˈfō-ˌtän
: a tiny particle of light or electromagnetic radiation
Medical Definition
photon
noun
pho·ton ˈfō-ˌtän
1
: a unit of intensity of light at the retina equal to the illumination received per square millimeter of a pupillary area from a surface having a brightness of one candela per square meter
called also troland
2
: a quantum of electromagnetic radiation