This title appears in the Scientific Report :
2001
Please use the identifier:
http://hdl.handle.net/2128/20675 in citations.
Messung der Hydroxylradikal-Konzentration in der marinen Troposphäre mittels laserinduzierter Floureszenz
Messung der Hydroxylradikal-Konzentration in der marinen Troposphäre mittels laserinduzierter Floureszenz
The concentrations of OH and H02 radicals were measured above the Atlantic ocean using LIF technique. The measurements were part of the field campaign ALBATROSS which took place aboard the German research vessel "Polarstern" in October 1996. Numerous diurnal cycles of OH and H02 were recor...
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Personal Name(s): | Sedlacek, Michael (Corresponding author) |
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Contributing Institute: |
Troposphäre; ICG-II |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2001
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Physical Description: |
VII, 117 p. |
Dissertation Note: |
Bonn, Univ., Diss., 2000 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
Troposphärische Chemie |
Series Title: |
Berichte des Forschungszentrums Jülich
3848 |
Subject (ZB): | |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
The concentrations of OH and H02 radicals were measured above the Atlantic ocean using LIF technique. The measurements were part of the field campaign ALBATROSS which took place aboard the German research vessel "Polarstern" in October 1996. Numerous diurnal cycles of OH and H02 were recorded in the marine boundary layer between 24° N and 32° S latitude . In this background atmosphere the OH concentration proved to be proportional to the photolysis frequency J(O('D)), whereas the H02 concentration correlated with the square root of AO( D)). Furthermore, the calibration method for the LIF experiment was verified and improved. The method is based on the photolysis of water vapour at 185 nm for radical generation and the dissociation of oxygen for irradiation measurement in the flow reactor. The produced radical concentration is proportional to the quotient of the absorption cross sections of both gases . A low-pressure mercury vapour lamp serves as light source. Measurements of the vuv emission spectrum revealed, that the shape of the 185 nm line is highly dependent on the particular lamp used and on its operating conditions. The line turned out to have a red tail which extended as far as 200 nm in single cases. The emission profile of the 185 nm line covers several oxygen Schumann-Runge-bands. Therefore, an effective 02 absorption cross section had to be determined for each particular lamp under well defined operating conditions. A thorough reproduction of these experiment specific parameters is required for a reliable field calibration. As literature data for the cross section of water vapour at 185 nm were inconsistent, its value was remeasured . The result, (7,1 ± 0,2) x 10-2° cm2, is in good agreement with the value determined by Cantrell et al. [1997]. In addition, an alternate calibration method was developed which makes use of the photolysis of nitrous oxide in synthetic air to measure the irradiation . The primary product is O(ID), which reacts partly with N20 to form either 02 and N2 or NO. The generated NOconcentration is detected. The branching ratio for the NO channel was determined with an error of 10 %. For the quantum yield of the spin-forbidden process of direct NO formation from N20 photolysis a new upper limit of 0.24 % was measured. While the new N20/NOactinometry has about the same accuracy as the oxygen actinometry, the influence of experiment specific parameters as well as the statistical error is very small compared to the conventional method |