FTIR analysis of aerosol formed in the photooxidation of 1,3,5-trimethylbenzene

The composition of aerosol generated in the photooxidation of 1,3,5-trimethylbenzene was investigated in a smog chamber experiment, The relative concentrations of alcohols, carboxylic acids, organonitrates, carbonyl groups, nitroaromatics, aliphatic C--H and aromatic C--H in the aerosol were estimated through analysis of infrared spectra. Based on model compound calibrations it was estimated that a typical molecule in the aerosol contained three carbonyl groups, six aliphatic C-H bonds, and one hydroxyl group, Small amounts of organic acids (one molecule in ten) and organonitrates (one molecule in four) were observed. About 5-10 wt% of the aerosol mixture was aromatic and these structures contained nitro and hydroxyl groups. This information on aerosol chemical functionality was coupled with gas-phase chemistry mechanisms to propose potential aerosol formation pathways. (C) 1997 American Association for Aerosol Research.