OH-initiated degradation mechanisms of aromatics and photooxidant-forming cycles of HOx

A radical amplifier for HO2/RO2 was established and characterized and the OH-initiated degradation of benzene was investigated in a smog chamber with simultaneous recording of the phenol product and HO2-levels. A phenol yield of 26+/-5% was found, independent of the applied OH concentrations. The reactions of OH with the three trimethylbenzene isomers and consecutive reactions of the OH-adducts with O2 were studied between 275 K and 340 K by resonance fluorescence detection of OH. Rate constants of OH + trimethylbenzenes are fast, 1-7.10[-11]cm3s-1, and show a slightly negative temperature dependence while the adduct + O2 reactions vary in the range 5-7.10-15cm3s-1.