Supporting Data for Enhanced Gas Uptake During a-Pinene Ozonolysis Points to a Burying Mechanism

Understanding how gases interact with and are incorporated into atmospheric secondary organic aerosol particles is crucial for predicting particle effects on climate and human health.  This work examined how three gaseous organic nitrates (ON) are taken up into viscous particles formed from the ozonolysis of α-pinene (AP).  Experiments were performed in a flow reactor at room temperature under dry conditions, either with or without an OH scavenger present, with constant ozone and variable AP concentrations.  Each ON was introduced independently into the flow reactor and was present during particle formation/growth.  ON gas phase concentrations were determined by gas chromatography-mass spectrometry and particle phase concentrations were measured by high-resolution time-of-flight mass spectrometry.  Partition coefficients (KSOA) for each ON were independent of the initial AP concentration, except for 2-ethylhexyl nitrate which was undetectable in the particles at the lowest AP concentrat...