Wikipedia - Allotropie de l'oxygène (fr) Wikipedia - Triplet oxygen (en) Wikipedia - 三线态氧 (zh) Wikipedia - 三重态氧 (zh) singlet molecular oxygen (singlet molecular dioxygen)

https://doi.org/10.1351/goldbook.S05695
Oxygen molecule (dioxygen), O2, in an excited @[email protected] The @[email protected] of O2 is a triplet ($$^{3}\mathit{\Sigma} _{g}^{-}$$). The two @[email protected] singlet states derived from the ground-state configuration are $$^{1}\Delta _{g}$$ and $$^{1}\mathit{\Sigma} _{g}^{+}$$ (the latter with the higher energy).
Notes:
1. Use of the term singlet oxygen alone, without mention of the chemical species is discouraged since it can also refer to an oxygen atom in a $$^{1}\text{S}$$ or $$^{1}\text{D}$$ @[email protected] The oxygen atom @[email protected] is a triplet $$^{3}\text{P}$$ state and the $$^{1}\text{S}$$ and $$^{1}\text{D}$$ states are also derived from the ground-state configuration.
2. @[email protected] @[email protected] by triplet dioxygen (i.e., a process of @[email protected]) is the most common procedure for the production of singlet molecular dioxygen in solution. For many chemical species, the efficiency with which the @[email protected] is quenched by triplet dioxygen and, independently, the efficiency with singlet molecular dioxygen is produced, is controlled by the [email protected]@.
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 420 [Terms] [Paper]