Physics
Photon Emission and Absorption in Quantum Electrodynamics
Quick fact
Photons are emitted when electrons in an atom transition from a higher energy level to a lower one, releasing energy as electromagnetic radiation.
Why this is interesting
Did you know that every photon is a quantum particle of light, and its emission or absorption is governed by precise rules at the atomic scale?
Read the full explanation
Understanding Photon Emission and Absorption in Quantum Electrodynamics
In QED, photons are not just particles but also mediators of electromagnetic forces. Their emission and absorption are governed by the quantum interactions between charged particles and the electromagnetic field.
A deeper explanation
Photon emission occurs when an electron in an excited state (higher energy level) transitions to a lower energy state, releasing a photon with energy matching the difference between these levels. This process is described by Fermi’s golden rule within QED. Similarly, absorption happens when a photon provides enough energy for an electron to jump from a lower to a higher energy level, which forms the basis of atomic spectra and many spectroscopic techniques. These interactions are governed by the quantization of electromagnetic fields and involve virtual photons as part of vacuum fluctuations.