title: Absorption Cross Sections of 2-Nitrophenol in the 295-400 nm Region and Photolysis of 2-Nitrophenol at 308 and 351 nm.
abstract: 2-Nitrophenol is an important component of "brown carbon" in the atmosphere. Photolysis is its dominant gas phase removal process. We have determined the gas phase absorption cross sections of 2-nitrophenol in the 295-400 nm region by using cavity ring-down spectroscopy. 2-Nitrophenol exhibits a broad absorption band over the wavelength region studied, with the peak absorption located at 345 nm. Absorption cross section values range between (2.86 ± 0.18) × 10-18and (2.63 ± 0.31) × 10-20cm2/molecule over the 295-400 nm range. We have investigated the HONO, NO2, and OH formation channels following the gas phase photolysis of 2-nitrophenol at 308 and 351 nm. Direct NO2formation was not observed. HONO and OH are direct products from 2-nitrophenol photolysis. The average OH quantum yields from the photolysis of 0.5, 1.0, and 2.0 mTorr of 2-nitrophenol are 0.69 ± 0.07 and 0.70 ± 0.07 at 308 and 351 nm. The average HONO quantum yields are 0.34 ± 0.09 and 0.39 ± 0.07 at 308 and 351 nm. The OH and HONO quantum yields are independent of nitrogen carrier gas pressure in the 20-600 Torr range. Oxidant formation rate constants from 2-nitrophenol photolysis have been calculated. Discussions have been made concerning the role of 2-nitrophenol gas phase photolysis in the formation of atmospheric oxidants in regions of high anthropogenic emissions.
authors.affiliation: Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, University at Albany , Albany, New York 12201-0509, United States.
authors.forename: Manuvesh
authors.initials: M
authors.lastname: Sangwan
authors.affiliation: Wadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, University at Albany , Albany, New York 12201-0509, United States.
authors.forename: Lei
authors.identifier: http://orcid.org/0000-0002-6916-1393
authors.initials: L
authors.lastname: Zhu