Volatility of secondary organic aerosol from β-caryophyllene ozonolysis between 213-313 K

Positive matrix factorization (PMF) was used to deconvolute the desorption data (thermograms) of SOA products detected by a chemical ionization mass spectrometer (FIGAERO-CIMS). A non-monotonic dependence of particle volatility (saturation concentration at 298 K, C_298K^*) on formation temperature (213-313 K) was observed, primarily due to temperature-dependent formation pathways of β-caryophyllene oxidation products.

The PMF analysis grouped detected ions into 11 compound groups (factors) with characteristic volatility. These compound groups act as indicators for the underlying SOA formation mechanisms. Their different temperature response revealed that the relevant chemical pathways (e.g., autoxidation, oligomer formation, and isomer formation) had distinct optimal temperatures between 213–313 K, significantly beyond the effect of temperature-dependent partitioning.