Darmstadt 2008 – scientific programme

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UP: Fachverband Umweltphysik

UP 5: Poster: Atmosphäre und Aerosole: Datenauswertung und Modellierung

UP 5.1: Poster

Tuesday, March 11, 2008, 16:30–19:00, Poster B1

Cavity Enhanced DOAS as a novel technique for trace gas detection. — •Jan Meinen¹, Jim Thieser², Ulrich Platt², and Thomas Leisner¹ — ¹Atmosphärische Aerosolforschung (IMK-AAF), Forschungszentrum Karlsruhe GmbH, 76344 Eggenstein-Leopoldshafen — ²Institut für Umweltphysik, Im Neuenheimer Feld 229, 69120 Heidelberg

A new instrument for measuring the trace gas radical NO3 in the ppt region by optical absorption was developed using a cavity enhanced absorption cell (CEAS). The standard technique of CEAS is very vulnerable to aerosol impact and background absorbers. Using a broadband light source in CEAS provides the feasibility of employing a differential fitting approach in the data acquisition and evaluation. The instrument is self calibrating by pulsing a LED in cavity ringdown approach (CRDS) to obtain mirror reflectivity for a certain wavelength. The combination of the broadband CEA approach utilizing LEDs and classical DOAS data analysis provides a remarkably simple, low cost and robust device for trace gas detection. Required additions of the standard CRD und CEA theory and the setup of the instrument will be shown. We call this new approach Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS). First laboratory and field data from the NO3/N2O5 intercomparison campaign at the SAPHIR chamber in Jülich will be used to discuss the operational reliability of the instrument.