An improved method of measuring tropospheric NO2 and RO2 by matrix isolation and electron spin resonance |
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| Authors: | D. Mihelcic P. Müsgen D. H. Ehhalt |
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| Affiliation: | (1) Institut für Chemie 2: Chemie der belasteten Atmosphäre, Kernforschungsanlage, Jülich GmbH, P.O. Box 1913, D-5170 Jülich, F.R.G.;(2) Institut für Chemie 3: Atmosphärische Chemie, Kernforschungsanlage, Jülich GmbH, P.O. Box 1913, D-5170 Jülich, F.R.G. |
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| Abstract: | A cryogenic system for the airborne and ground based sampling of ambient radicals by matrix isolation is described. The trapped radicals, e.g., NO2 and RO2, are analyzed by ESR. The technique has been improved, mainly by addition of water vapor to the sampled air, to yield a collection efficiency of (90±10)% and a lower detection limit of about 20 ppt, but it still does not distinguish between the different RO2. Careful calibration reduced the measurement error (1  ) to ±10% for NO2 and ±15% for HO2. Two diurnal variations of RO2 and NO2 at ground level and vertical profiles in the lower troposphere are presented. |
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| Keywords: | Peroxyradicals NO2 in-situ measurement matrix isolation electron spin resonance |
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