Relaxation and Reactivity of Singlet Oxygen

The origin of the chemiluminescence of phagocytosing granulocytes.

“…The failure to detect chemiluminescence attributable to the relaxation of singlet to triplet (ground state) oxygen does not constitute evidence against its formation, since it can be consumed in chemical reactions, some of which yield other light-emitting species, and, in addition, can relax to the ground state by nonradiative processes in which its excess energy is liberated as heat, not light (40,41). In view-of the fact that singlet oxygen is a product of at least two reactions which could.…”

Mechanisms in sensitized photochemistry of environmental chemicals

“…16c Oxygen possesses two metastable singlet states with spectroscopic symmetry notations ^^(STkcal/mole) and 1 state is long-lived and survives at least 10 8 collisions with methanol in the vapour phase, whereas the ^g state does no more than 10 collisions under the same conditions. 20 Oxygen in its 1 A g state has been detected by its luminescence 21 and paramagnetic resonance spectra 22 -23 as a product of photosensitization in the gas phase. Now it is generally accepted that ,,02 is involved in photo-oxidation, 14 ' 24 although possible involvement of 1 Y d g O 2 m suc^ react i°n s nas been suggested in the past by inter alia Kearns et al 25 The efficiency of each path (radical mechanism and singlet oxygen mechanism) depends on the relative concentrations of oxygen and substrate, the rates of reaction of sensitizer triplet with substrate (k s ), see Eq.…”

The Quenching of O2(1Σg+) by Aliphatic Hydrocarbons

“…In the last five years a number of laboratories Experimental have reported rate constants for the quenching of 02('C,+) in the gas phase (1)(2)(3)(4)(5)(6). It would appear that in all cases the quenching did not involve chemical reaction, and 02(lC,+) was relaxed to O,('A,) which lies only 15 kcal below it (7,8).…”