Phenomena and Processes

Photons

Discrete concentrations of energy, apparently massless elementary particles, that move at the speed of light. They are the unit or quantum of electromagnetic radiation. Photons are emitted when electrons move from one energy state to another. (From Hawley's Condensed Chemical Dictionary, 11th ed)

National Library of MedicineMedical Subject Headings2026

Structured Summary

Abstract

Discrete concentrations of energy, apparently massless elementary particles, that move at the speed of light. They are the unit or quantum of electromagnetic radiation. Photons are emitted when electrons move from one energy state to another. (From Hawley's Condensed Chemical Dictionary, 11th ed)

MeSH Record

Classification

Broader headings

Related Concepts

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MeSH Record

Aspects Covered

4 allowable subheadings

Indexed with the subheadings adverse effects, classification, history, therapeutic use.

MeSH Record

Indexing Annotation

elementary particles; IM

MeSH Record

History Note

94; was see RADIATION 1985-1993

MeSH Hierarchy

Tree Numbers

  1. G01w.249w.705w
  2. G01w.358.500.505w.650w.782w
  3. G01w.590w.540w.782w
  4. G01w.750w.250w.650w.782w
  5. G01w.750w.770w.578w.782w

AMA Style

References

  1. National Library of Medicine. Photons. Medical Subject Headings (MeSH). 2026. Unique ID D017785. http://id.nlm.nih.gov/mesh/2026/D017785
  2. Photons. In: Wikipedia. https://en.wikipedia.org/wiki/Photon
  3. Photons. In: Wikidata. https://www.wikidata.org/wiki/Q3198