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Naphthalene is the most abundant polycyclic aromatic hydrocarbon (PAH) in polluted urban areas. Naphthalene is present in the gas phase under typical atmospheric conditions, and its most important atmospheric loss process is reaction with the hydroxyl (OH) radical. The products of the gas-phase reaction of naphthalene with OH radicals and with nitrate (NO 3 ) radicals have been investigated using gas chromatographic techniques with flame ionization, mass spectrometric, and Fourier transform infrared spectroscopic detection and using in situ atmospheric pressure ionization mass spectrometry. The major products identified from the OH radical-initiated reaction of gas-phase naphthalene were ring cleavage species, including 2-formylcinnamaldehyde. The major products observed from the NO 3 radical-initiated reaction were 1-and 2-nitronaphthalene.

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Isomerizations of the alkoxy radicals formed from the OH radical reactions with n-butane through n-octane and n-pentane-d 12 through n-octane-d 18 have been studied in the presence of NO at 296 ± 2 K and 740 Torr total pressure of air. In addition to carbonyls of the same carbon number as the alkane precursors, the previously predicted δ-hydroxycarbonyls were detected by direct air sampling atmospheric pressure ionization triple quadrupole mass spectrometry. The formation yields of carbonyl compounds containing the same number of carbons as the parent n-alkane decreased with increasing carbon number in the n-alkane, while the hydroxycarbonyl/carbonyl formation yield ratios increased markedly from n-butane through n-octane, in agreement with previous theoretical predictions.