Fig. 2

The relative changes in the abundances of SOA products, identified by the FIGAERO-HR-CIMS, in the particle phase upon addition of sulfate seeds during AP ozonolysis in the COALA chamber. Changes are quantified by the ratios indicated in the legends and depicted using the (logarithmic) color scale, and presented as a function of the number of oxygen and carbon atoms in the identified molecules. Each data point is the sum over several ions with different number of hydrogen atoms. a and c represent the experiments performed with AS under dry and humid conditions, respectively, while b and d represent the experiments conducted with ABS under dry and humid conditions, respectively