AMT Atmospheric Measurement Techniques AMT Atmos. Meas. Tech. 1867-8548 Copernicus Publications Göttingen, Germany 10.5194/amt-3-593-2010 Total Peroxy Nitrates (ΣPNs) in the atmosphere: the Thermal Dissociation-Laser Induced Fluorescence (TD-LIF) technique and comparisons to speciated PAN measurements Wooldridge P. J. 1 Perring A. E. 1 Bertram T. H. 2 Flocke F. M. 3 Roberts J. M. 4 Singh H. B. 5 Huey L. G. 6 Thornton J. A. 7 Wolfe G. M. 7 Murphy J. G. 8 Fry J. L. 9 Rollins A. W. 1 LaFranchi B. W. 1 Cohen R. C. 1 10 Department of Chemistry, University of California, Berkeley, CA, USA Department of Chemistry and Biochemistry, University of San Diego, La Jolla, CA, USA NCAR Atmospheric Chemistry Division, Boulder, CO, USA NOAA Earth System Research Laboratory, Boulder, CO, USA NASA Ames Research Center, Moffett Field, CA, USA School of Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA Department of Chemistry, University of Toronto, Toronto, Ontario, Canada Department of Chemistry, Reed College, Portland, OR, USA Department of Earth and Planetary Science, University of California, Berkeley, CA, USA 12 05 2010 3 3 593 607 Copyright: © 2010 P. J. Wooldridge et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://amt.copernicus.org/articles/3/593/2010/amt-3-593-2010.html The full text article is available as a PDF file from https://amt.copernicus.org/articles/3/593/2010/amt-3-593-2010.pdf

Peroxyacetyl nitrate (PAN) and its chemical analogues are increasingly being quantified in the ambient atmosphere by thermal dissociation (TD) followed by detection of either the peroxyacyl radical or the NO<sub>2</sub> product. Here we present details of the technique developed at University of California, Berkeley which detects the sum of all peroxynitrates (&Sigma;PNs) via laser-induced fluorescence (LIF) of the NO<sub>2</sub> product. We review the various deployments and compare the Berkeley &Sigma;PNs measurements with the sums of PAN and its homologue species detected individually by other instruments. The observed TD-LIF &Sigma;PNs usually agree to within 10% with the summed individual species, thus arguing against the presence of significant concentrations of unmeasured PAN-type compounds in the atmosphere, as suggested by some photochemical mechanisms. Examples of poorer agreement are attributed to a sampling inlet design that is shown to be inappropriate for high NO<sub>x</sub> conditions. Interferences to the TD-LIF measurements are described along with strategies to minimize their effects.

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