Heterogeneous uptake of NO2 on Arizona Test Dust under UV-A irradiation: An aerosol flow tube study

Abstract

Abstract The uptake rate of NO 2 on Arizona Test Dust aerosols was measured using an aerosol flow tube (AFT). While the uptake rate in the dark could not be measured, the uptake under UV-A irradiation was enhanced, with values in the range from (0.6 ± 0.3) × 10 −8 , (2.4 ± 0.4) × 10 −8 . The observed gas phase products were HONO and NO, with yields of at 30% and 9.6%, respectively. The difference between these measurements and those previously reported on macroscopic films are discussed and differences highlighted. Interestingly, a reasonable agreement is observed between the uptake kinetics of NO 2 on Arizona Test Dust macroscopic films and aerosols, despite the different experimental approaches. The simplest approach i.e. thin films having a significant porosity, provides similar uptake kinetics to the more complex and realistic AFT approach.