Effect of CH3OOH on the atmospheric concentration of OH radicals

Abstract

Abstract Methyl hydroperoxide (CH3OOH, MHP) is known to be a significant sink and reservoir of HOx and ROx radicals in the atmosphere. In order to investigate the impact of MHP on the concentration of atmospheric OH radicals, two key gas-phase reactions of MHP, i.e. the reactions with OH radicals and with UV photolysis, have been simulated at temperature of 293±2 K and total pressure of 1.01×105 Pa, using the long path Fourier transform infrared (LP-FTIR) spectometry. OH radicals are generated by the photolysis of O3 in the presence of water vapor. Combined with the relative rate method, the reaction rate constant of MHP with OH radicals is determined to be (3.99±0.15)×10-12 cm3 molecule-1 s-1, and thus the atmospheric lifetime of MHP is estimated at 2.9 days. Furthermore, from detailed analysis of the UV photolysis of MHP, the yield of OH radicals is obtained to be 0.91±0.04. Based on the MHP atmospheric lifetime and the yield of OH radicals, it is concluded that MHP plays an essential role in the distri...