The nitroxide, 3-amino-2,2,5,5,-tetramethy-1-pyrrolydinyloxy (3ap), was employed to determine the initial rates of photoproduction of one-electron reductants (RH) from SRFA and SRHA. Evidence will be provided that O2 and 3ap compete for the same pools of photoproduced reductants and thus that RH can provide reliable estimates of the initial rates of O2- production (RO2-). Under identical irradiation conditions,RH was found to be far larger than the initial rates of H2O2 production (RH2O2), suggesting that the ratio of RO2-/ RH2O2 is larger than most previous reports, approximately 6-10. The results thus imply that a significant fraction of O2- is lost through through other (oxidative) pathways rather than simply through dismutation to H2O2. Possible oxidative reaction pathways will be discussed, as well as the possible relationship between the quantum yields of photoreductant formation and carbon dioxide photoproduction.

Molecular probe measurements of the photochemical formation of one-electron reductants by CDOM: Relation to superoxide and hydrogen peroxide photoproduction

251st National Meeting (2016)

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