FTIR Analysis of Aerosol Formed in the Photooxidation of Naphthalene

A low pressure impactor (LPI) was used to collect aerosol generated in the photooxidation of naphthalene. The aerosol was generated in an environmental chamber and was analyzed using Fourier Transform Infrared Spectroscopy (FTIR). The relative molar concentrations of functional groups in the aerosol were estimated based on model compound calibrations. The relative molar concentrations for aliphatic C-H and carbonyl groups averaged 1.4 and 3.2 groups per average molecule, respectively. Hydroxyl, nitroaromatic, and organonitrate groups had concentrations of 0.6, 0.2, and 0.2 groups per average molecule, respectively. Only 2.4 groups of aromatic C-H per average molecule were observed. These structural characterizations of aerosol products were used to evaluate aerosol formation mechanisms. The analysis suggests that ring-opening reactions predominate.