ATMOSPHERIC CHEMISTRY OF THE REACTION CLO+O2[--]CLO.O2 - WHERE IT STANDS, WHAT NEEDS TO BE DONE, AND WHY

Possible existence and chemistry of ClO . O2 was originally proposed to explain the Norrish-Neville effect that O2 suppresses chlorine photosensitized loss of ozone. It was also thought that ClO . O2 might have some atmospheric chemistry significance. Recently, doubts have been cast on this proposal, because certain laboratory data seem to imply that the equilibrium constant of the title reaction is so small that ClO . O2 may be too unstable to matter. However, those data create only a superficial illusion to that effect, because on a closer analysis they do not disprove a moderately stable and chemically significant ClO . O2. Furthermore, our state-of-the-science accurate computational chemistry calculations also suggest that ClO . O2 may be a weakly bound C1OOO radical with a reactive 2A ground electronic state. There is therefore a need to design and perform definitive experimental tests of the existence and chemistry of the ClO . O2 species, which we discuss and which have the potential to mediate the chlorine-catalyzed stratospheric ozone depletion.