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@PHDTHESIS{Sedlacek:13477,
author = {Sedlacek, Michael},
title = {{M}essung der {H}ydroxylradikal-{K}onzentration in der
marinen {T}roposphäre mittels laserinduzierter
{F}loureszenz},
volume = {3848},
issn = {0944-2952},
school = {Univ. Bonn},
type = {Dr. (Univ.)},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {PreJuSER-13477, Juel-3848},
series = {Berichte des Forschungszentrums Jülich},
pages = {VII, 117 p.},
year = {2001},
note = {Record converted from VDB: 12.11.2012; Bonn, Univ., Diss.,
2000},
abstract = {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},
cin = {ICG-II},
cid = {I:(DE-Juel1)VDB48},
pnm = {Troposphärische Chemie},
pid = {G:(DE-Juel1)FUEK74},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
url = {https://juser.fz-juelich.de/record/13477},
}