Effect of the OH Radical Scavenger Hydrogen Peroxide on Secondary Organic Aerosol Formation from α-Pinene Ozonolysis

Hydrogen peroxide (HOOH) is a potentially valuable hydroxyl radical (OH) scavenger in secondary organic aerosol experiments focused on ozonolysis yields. Here, we present results for alpha-pinene ozonolysis. The OH scavenging produces solely HO(2) radicals and the resulting high [HO(2)]/[RO(2)] ratio causes an increase in aerosol formation from alpha-pinene ozonolysis, compared to experiments performed with butanol OH scavengers. The majority of the increase comes in the 100 mu g m(-3) volatility range, suggesting that instead of more volatile products formed under higher RO(2) conditions, less volatile, multifunctional hydroperoxides form under the high-HO(2) conditions here. This dependence on the [HO(2)]/[RO(2)] ratio can be parameterized in a similar fashion to the way high- and low-NO(x) yields are currently treated in models.