Fig. 1.

Formaldehyde and methanol time profiles from the methylperoxy self- and hydroxyl reactions. Comparison of the contributions from ¹³CH₃OO self-reaction and reaction of ¹³CH₃OO with OH in producing methanol in the photolysis experiments at P = 30 Torr. a CH₃OO self-reaction (photolysis of ¹³CH₃I in the presence of O₂) compared to a kinetic model employing literature rate coefficients and directly measured reactant concentrations, wall loss and two fits to the photolytic depletion. b Measurements at the same conditions as (a) except with the addition of H₂O₂. The contribution from ¹³CH₃OO self-reaction is represented by the signal from another product at m/z = 64, ¹³CH₃OO¹³CH₃ (formed only by the self-reaction), scaled using directly measured branching fractions of the self-reaction. The additional, rapidly formed ¹³CH₃OH arises from the reactions of ¹³CH₃OO with OH and ¹³CH₃O with HO₂. The temporal resolution of the methanol and CH₃OOCH₃ signals is here reduced by a factor of five to more clearly show the amplitudes