Impact of humidity on the ozone initiated oxidation of limonene, delta3-carene, and alpha-pinene

The effect of water on the initial secondary organic aerosol (SOA) formation from gas-phase ozonolysis of limonene, delta3-carene, and alpha-pinene (-3 and approximately 1.5 x 10(11) molecule cm(-3) reacted) has been investigated in a flow reactor at controlled relative humidity (RH), temperature (298 +/- 0.4 K), and reaction time (270 +/- 2 s). Low amounts of terpene converted minimize the impact of secondary reactions. A comparison of the SOA formation from the three terpenes was made for initial rate of reactions being around 7.5 x 10(8) and 15 x 10(8) molecule cm(-3) s(-1). The most efficient species in producing SOA was limonene, while alpha-pinene was the least efficient. The results showed that an enhancement in water vapor concentration (