Using a high finesse optical resonator to provide a long light path for differential optical absorption spectroscopy: CE-DOASReport as inadecuate




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1 IMK - Institute for Meteorology and Climate Research 2 Institut for Environmental Physics IUP

Abstract : Cavity enhanced methods in absorption spectroscopy have seen a considerable increase in popularity during the past decade. Especially Cavity Enhanced Absorption Spectroscopy CEAS established itself in atmospheric trace gas detection by providing tens of kilometers of effective light path length using a cavity as short as 1 m. In this paper we report on the construction and testing of a compact and power efficient light emitting diode based broadband Cavity Enhanced Differential Optical Absorption Spectrometer CE-DOAS for in situ field observation of atmospheric NO3. This device combines the small size of the cavity with the enormous advantages of the DOAS approach in terms of sensitivity and specificity. In particular, no selective removal of the analyte here NO3 is necessary, thus the CE-DOAS technique can ? in principle ? measure any gas detectable by DOAS. We will discuss the advantages of using a light emitting diode LED as light source particularly the precautions which have to be satisfied for the use of LEDs. The instrument was tested in the lab by detecting NO3 in a mixture of NO2 and O3 in air. It was then compared to other trace gas detection techniques in an intercomparison campaign in the atmosphere simulation chamber SAPHIR at NO3 concentrations as low as 6.3 ppt.





Author: J. Meinen - J. Thieser - U. Platt - T. Leisner -

Source: https://hal.archives-ouvertes.fr/



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