Absorption Cross Sections of 2-Nitrophenol in the 295–400 nm Region and Photolysis of 2-Nitrophenol at 308 and 351 nm
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- 作者：Manuvesh Sangwan ; Lei Zhu
- 刊名：Journal of Physical Chemistry A
- 出版年：2016
- 出版时间：December 22, 2016
- 年：2016
- 卷：120
- 期：50
- 页码：9958-9967
- 全文大小：453K
- ISSN：1520-5215
文摘
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) × 10–18 and (2.63 ± 0.31) × 10–20 cm2/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 NO2 formation 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.