Volatility measurements of photochemically and nebulizer-generated organic aerosol particles

A volatility-tandem differential mobility analyzer (VTDMA) was designed to monitor the non-volatile fraction of reaction chamber-generated organic aerosol particles. Using a coiled-tube heater for particle volatilization, an analysis of the carrier gas temperatures was made for wall temperatures of 100, 150, and 200 ^{{ring operator}} C. Oligomerization in organic aerosol particles generated from irradiations of α-pinene/NO_x/H₂ O/pure air in a reaction chamber shows a strong linear relationship with time and has an oligomerization rate of 1.3 % h^{- 1} for the 100 ^{{ring operator}} C wall temperature case. This rate is almost three times slower than the previously published rate for irradiations of 1, 3, 5-trimethylbenzene/NO_x/H₂ O/pure air. In addition, experiments using the VTDMA demonstrated that oligomerization of nebulizer-generated methylglyoxal particles can occur in the absence of NO_x, propene, and irradiation. The oligomerization of organic aerosol particles has implications which are highly relevant to the atmosphere, such as influencing hygroscopic growth and cloud condensation nuclei activation.