A pulse radiolysis and flash photolysis study of the radicals SO2-, SO3-, SO4- and SO5-

Pulse radiolysis and laser-flash photolysis have been used to generate the radicals SO2-, SO3-, SO4- and SO5-. Optical absorption spectra for these radicals and rate constants for their self-reactions have been derived. The decay of SO2-, SO3- and SO4- follow simple second-order kinetics; the decay of SO5- is slower and does not follow a second-order rate law when the radical is generated by the pulse radiolysis of an oxygenated sulfite or bisulfite solution, but is second-order when generated by the flash photolysis of an oxygenated dithionate solution. SO2- reacts rapidly with O2 and a rate constant of 2.4 x 109 M-1 s-1 was derived. SO3- also reacts rapidly with O2 and a rate constant of 1.1 x 109 M-1 s-1 was derived for this reaction. The rate constant for the reaction of H with SO2 was determined to be 2.9 x 109 M-1 s-1. (author)