ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-10-6169-2010 Isoprene nitrates: preparation, separation, identification, yields, and atmospheric chemistry Lockwood A. L. 1 3 Shepson P. B. 1 2 Fiddler M. N. 1 Alaghmand M. 1 Department of Chemistry, Purdue University, 560 Oval Dr. West Lafayette, IN 47907, USA Department of Earth and Atmospheric Sciences, Purdue University, 560 Oval Dr. West Lafayette, IN 47907, USA currently at: Clarion University of PA, Dept. of Chemistry and Biochemistry, 840 Wood St., Clarion, PA 16214, USA 08 07 2010 10 13 6169 6178 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/10/6169/2010/acp-10-6169-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/10/6169/2010/acp-10-6169-2010.pdf

Isoprene is an important atmospheric volatile organic compound involved in ozone production and NO<sub>x</sub> (NO+NO<sub>2</sub>) sequestration and transport. Isoprene reaction with OH in the presence of NO can form either isoprene hydroxy nitrates ("isoprene nitrates") or convert NO to NO<sub>2</sub> which can photolyze to form ozone. While it has been shown that isoprene nitrate production can represent an important sink for NO<sub>x</sub> in forest impacted environments, there is little experimental knowledge of the relative importance of the individual isoprene nitrate isomers, each of which has a different fate and reactivity. In this work, we have identified the 8 individual isomers and determined their total and individual production yields. The overall yield of isoprene nitrates at atmospheric pressure and 295 K was found to be 0.070(+0.025/−0.015). Three isomers, representing nitrates resulting from OH addition to a terminal carbon, represent 90% of the total IN yield. We also determined the ozone rate constants for three of the isomers, and have calculated their atmospheric lifetimes, which range from ~1–2 h, making their oxidation products likely more important as atmospheric organic nitrates and sinks for nitrogen.

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