Tropospheric Chemistry: Instruments

PAN CIMS instrument

PAN CIMS instrument in the laboratory

PAN CIMS (Chemical Ionization Mass Spectrometer)

Principle of the Measurement

Chemical ionization mass spectrometric detection of carboxylate ions produced via reaction of thermally produced acylperoxy radicals with I-

Species Measured

Acyl peroxynitrate species, e.g. acetyl peroxynitrate (PAN), propionyl peroxynitrate (PPN), acryloyl peroxynitrate (APAN), methacryloyl peroxynitrate (MPAN) and crotonyl peroxynitrate (CPAN)
Nitryl Chloride (ClNO2)

Time Response

1 second

Detection Limit

Precision on 1s data 20 pptv


± (20% + 40 pptv) for PAN
± (20% + 40 pptv) for CINO2

Field Projects

  • TexAQS 2006
  • ARCPAC 2008
  • CalNEX 2010
  • Gulf 2010
  • NACHTT 2011
  • UBWOS 2012-2014
  • SENEX 2013
  • SONGNEX 2015


  • NOAA WP-3D aircraft
  • Erie Tower
  • NOAA R/V Ronald H. Brown
  • ground sites


Patrick Veres

Key Publications

Veres, P.R., and J.M. Roberts, Development of a photochemical source for the production and calibration of acyl peroxynitrate compounds, Atmospheric Measurement Techniques, doi:10.5194/amt-8-2225-2015, 2015.

Zheng, W., F.M. Flocke, G.S. Tyndall, A. Swanson, J.J. Orlando, J.M. Roberts, L.G. Huey, and D.J. Tanner, Characterization of a thermal decomposition chemical ionization mass spectrometer for the measurement of Peroxy Acyl Nitrates (PANs) in the atmosphere, Atmospheric Chemistry and Physics, doi:10.5194/acp-11-6529-2011, 2011.

Osthoff, H.D., J.M. Roberts, A.R. Ravishankara, E.J. Williams, B.M. Lerner, R. Sommariva, T.S. Bates, D. Coffman, P.K. Quinn, J.E. Dibb, H. Stark, J.B. Burkholder, R.K. Talukdar, J. Meagher, F.C. Fehsenfeld, and S.S. Brown, High levels of nitryl chloride in the polluted subtropical marine boundary layer, Nature Geoscience, doi:10.1038/ngeo177, 2008.