Journal Article

PreJuSER-3832

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Measurement of glyoxal using an incoherent broadband cavity enhanced absorption spectrometer

Washenfelder, R. A. ; Langford, A. O. ; Fuchs, H.FZJ* ; Brown, S. S.

2008
EGU Katlenburg-Lindau

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Please use a persistent id in citations: http://hdl.handle.net/2128/10174

Abstract: We describe an instrument for simultaneous measurements of glyoxal (CHOCHO) and nitrogen dioxide (NO2) using cavity enhanced absorption spectroscopy with a broadband light source. The output of a Xenon arc lamp is coupled into a 1m optical cavity, and the spectrum of light exiting the cavity is recorded by a grating spectrometer with a charge-coupled device (CCD) array detector. The mirror reflectivity and effective path lengths are determined from the known Rayleigh scattering of He and dry zero air (N-2+O-2). Least-squares fitting, using published reference spectra, allow the simultaneous retrieval of CHOCHO, NO2, O-4, and H2O in the 441 to 469 nm spectral range. For a 1-min sampling time, the precision (+/- 1 sigma) on signal for measurements of CHOCHO and NO2 is 29 pptv and 20 pptv, respectively. We directly compare measurements made with the incoherent broadband cavity enhanced absorption spectrometer with those from cavity ringdown instruments detecting CHOCHO and NO2 at 404 and 532 nm, respectively, and find linear agreement over a wide range of concentrations. The instrument has been tested in the laboratory with both synthetic and real air samples, and the demonstrated sensitivity and specificity suggest a strong potential for field measurements of both CHOCHO and NO2.

Keyword(s): J

Note: We thank Karl Feierabend for his assistance in synthesizing glyoxal. We thank Rich McLaughlin for machining custom mirror mounts for the IBBCEAS instrument. We thank Susan Solomon for the loan of the InSpectrum 150. We thank Rainer Volkamer and Bill Dube for useful discussions. RAW acknowledges support from the National Research Council Research Associateship Program. This work was funded in part by NOAA's Health of the Atmosphere and Atmospheric Chemistry and Climate programs.

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Research Program(s):

1. Atmosphäre und Klima (P22)

Appears in the scientific report 2008
Notes: Nachtrag

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