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Proceedings Paper

Light emitting diode cavity enhanced differential optical absorption spectroscopy (LED-CE-DOAS): a novel technique for monitoring atmospheric trace gases
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Paper Abstract

The combination of Cavity Enhanced Absorption Spectroscopy (CEAS) with broad-band light sources (e.g. Light- Emitting Diodes, LEDs) lends itself to the application of cavity enhanced DOAS (CE-DOAS) to perform sensitive and selective point measurements of multiple trace gases with a single instrument. In contrast to other broad-band CEAS techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e., does not require knowledge of the light intensity in the absence of trace gases and aerosols (I0). We have built a prototype LED-CE-DOAS instrument in the blue spectral range (420-490nm) to measure nitrogen dioxide (NO2), glyoxal (CHOCHO), iodine monoxide (IO), water (H2O) and oxygen dimers (O4). Aerosol extinction is retrieved at two wavelengths by means of observing water and O4 and measuring pressure, temperature and relative humidity independently. The instrument components are presented, and the approach to measure aerosol extinction is demonstrated by means of a set of experiments where laboratory generated monodisperse aerosols are added to the cavity. The aerosol extinction cross section agrees well with Mie calculations, demonstrating that our setup enables measurements of the above gases in open cavity mode.

Paper Details

Date Published: 24 August 2009
PDF: 10 pages
Proc. SPIE 7462, Ultraviolet and Visible Ground- and Space-based Measurements, Trace Gases, Aerosols and Effects VI, 74620H (24 August 2009); doi: 10.1117/12.826737
Show Author Affiliations
Ryan M. Thalman, Univ. of Colorado at Boulder (United States)
Cooperative Institute for Research in Environmental Studies (United States)
Rainer M. Volkamer, Univ. of Colorado at Boulder (United States)
Cooperative Institute for Research in Environmental Studies (United States)


Published in SPIE Proceedings Vol. 7462:
Ultraviolet and Visible Ground- and Space-based Measurements, Trace Gases, Aerosols and Effects VI
Jay R. Herman; Wei Gao, Editor(s)

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