|This article relies largely or entirely upon a single source. (December 2010)|
A photon is absorbed, causing an electron to jump to a higher energy level from which, after a delay, it falls back to its original level, emitting a photon having the same energy as the one absorbed. The emission direction is random.
A photon, generally in a higher energy range, can also be absorbed by an atomic nucleus, and then new photons having lower energies are emitted in random directions as the nucleus relaxes. See nuclear resonance fluorescence.
- "Resonance Fluorescence" (pdf). IUPAC Compendium of Chemical Terminology. IUPAC. 1997. Retrieved 2013-02-20.