Oxygen molecule (dioxygen),
O2, in an excited singlet state. The ground state of
O2 is a triplet (3Σg-). The two metastable singlet states derived from the ground-state configuration are 1Δg and 1Σg+ (the latter with the higher energy).
Notes: - 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 1S or 1D @E02257@. The oxygen atom @G02704@ is a triplet 3P state and the 1S and 1D states are also derived from the ground-state configuration.
- @T06503-1@ @Q05007@ by triplet dioxygen (i.e., a process of @P04652@) is the most common procedure for the production of singlet molecular dioxygen in solution. For many chemical species, the efficiency with which the @T06503-2@ is quenched by triplet dioxygen and, independently, the efficiency with singlet molecular dioxygen is produced, is controlled by the spin-@R05175@.
Source:
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 420 (https://doi.org/10.1351/pac200779030293)