Photo-oxidation
Photooxidations are oxidation reactions that are triggered by light . The rate of reaction of the oxidation depends, among other parameters, on the light absorption of the oxidized species.
mechanism
A photon excites an electron in a molecule so that it is raised to a higher energy level. In this excited state there is generally a low probability that the electron will spin flip, i.e. that the excited molecule will go into the triplet state .
If oxygen is now in the immediate vicinity (overlapping of the molecular orbitals ) to the molecule, the energy can be transferred, i.e. H. the molecule goes into the ground state and the oxygen into the excited state. The result is highly reactive singlet oxygen, which can enter into an oxidation reaction with the molecule.
Since oxygen has a triplet ground state (which is extremely rare), the energy transfer only works from the triplet state of the molecule by means of Dexter energy transfer , since this is the only way to maintain spin.
Web links
- Technical exhaust air purification through photooxidation (PDF file; 19 kB)
Individual evidence
- ↑ Harun Parlar, Daniela Angerhöfer: Chemical Ecotoxicology . Springer, 1995, p. 60 ( limited preview in Google Book search).