Spontaneous emission of radiation from an electronically or vibrationally excited species not in thermal
equilibrium with its environment.
Source:
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2252
PAC, 1994, 66, 2513
(Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994))
on page 2522
See also:
Orange Book, p. 184Orange Book, p. 231
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2200