Laboratory and modelling studies of tropospheric multiphase conversions involving some C1 and C2 peroxyl radicals

T-dependent rate constants for the self-reaction of selected peroxyl radica ls in aqueous solution have been determined. For C2H5O2, HOCH2O2 and C2H4(O H)O-2. negative activation energies have been found. The redox potential of CH3O2., HOCH2O2, O2CH2COOH can be estimated to E-0 < 1 V due to reactivity against NO2-. The rate constant for the reaction of the methylperoxyl radi cal with bisulfite (HSO3-) at T = 298 K and pH 4 has been determined to k = (5 +/- 1).10(5) l.mol(-1) .s(-1). This reaction may be an important sink f or the methylperoxyl radical in the condensed phase of the atmosphere at da ytime. This is demonstrated by including the corresponding reactions into a box model (CAPRAM 2.3.). (C) 1999 Elsevier Science Ltd. All rights reserve d.