Design and characterization of a smog chamber for studying gas-phase chemical mechanisms and aerosol formation

We describe here characterization of a new state-of- the-art smog chamber facility for studying atmospheric gas-phase and aerosol chemistry. The chamber consists of a 30m(3) fluorinated ethylene propylene (FEP) Teflon film reactor housed in a temperature-controlled enclosure equipped with black lamps as the light source. Temperature can be set in the range from -10 to 40 degrees C at accuracy of +/- 1 degrees C as measured by eight temperature sensors inside the enclosure and one just inside the reactor. Matrix air can be purified with non-methane hydrocarbons (NMHCs) < 0.5 ppb, NOx/O-3/carbonyls < 1 ppb and particles < 1 cm(-3). The photolysis rate of NO2 is adjustable between 0 and 0.49 min(-1). At 298K under dry conditions, the average wall loss rates of NO, NO2 and O-3 were measured to be 1.41 x 10(-4) min(-1), 1.39 x 10(-4) min(-1) and 1.31 x 10(-4) min-1, respectively, and the particle number wall loss rate was measured to be 0.17 h(-1). Auxiliary mechanisms of this chamber are determined and included in the Master Chemical Mechanism to evaluate and model propene-NOx-air irradiation experiments. The results indicate that this new smog chamber can provide high-quality data for mechanism evaluation. Results of alpha-pinene dark ozonolysis experiments revealed secondary organic aerosol (SOA) yields comparable to those from other chamber studies, and the two-product model gives a good fit for the yield data obtained in this work. Characterization experiments demonstrate that our Guangzhou Institute of Geochemistry, Chinese Academy Sciences (GIG-CAS), smog chamber facility can be used to provide valuable data for gas-phase chemistry and secondary aerosol formation.