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Detection of tropospheric OH and HO2 by laser-induced fluorescence at low pressure using the 308nm excitation of OHLaser-induced fluorescence (LIF) spectroscopy is a highly sensitive method for the direct in situ measurement of hydroxyl concentrations in the atmosphere. Its sensitivity and selectivity relies on the intense discrete UV-absorption lines of OH which are strongest around 282nm and 308nm. We have developed a LIF-instrument based on the low-pressure experiment (FAGE). However, we use 308nm instead of 282nm as excitation wavelength for OH, a concept that is also pursued by other groups. One advantage of the longer excitation wavelength is the higher detection sensitivity due to the about 6 times larger effective OH-fluorescence cross-section. Moreover, the O3/H2O-interference (OH self-generation by the laser) is about a factor of 200 smaller at 308nm than at 282nm. This keeps the interference level well below the projected detection limit of 10(exp 5) OH/cm(exp 3). Atmospheric HO2-radicals are detected by chemical conversion of HO2 into OH with NO.
Document ID
19940024088
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Hofzumahaus, Andreas
(Forschungszentrum Juelich G.m.b.H. Juelich, Germany)
Holland, Frank
(Forschungszentrum Juelich G.m.b.H. Juelich, Germany)
Date Acquired
September 6, 2013
Publication Date
February 1, 1994
Publication Information
Publication: SRI International Corp., Local Measurement of Tropospheric HO(x)
Subject Category
Environment Pollution
Accession Number
94N28591
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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