Description: Das Projekt "Entwicklung eines mobilen Feldinstruments fuer die schnelle simultane Messung von OH- und HO2-Radikalen in der Troposphaere durch laserinduzierte Fluoreszenz mit hoher Wiederholungsrate" wird vom Umweltbundesamt gefördert und von Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre durchgeführt. Objective: This project aims to develop an operative mobile field instrument for the highly sensitive, fast in-situ measurement of OH and HO2 in the troposphere. The oxidizing capacity of the troposphere is mainly determined by the concentration of hydroxyl-radicals (OH), which control the removal of most naturally and anthropogenically produced atmospheric trace gases. Thus, the understanding of the tropospheric chemistry requires the direct measurement of OH-radicals in the atmosphere. There is an urgent need for highly sensitive instruments that can measure tropospheric OH-concentrations with good temporal and spatial resolution. Furthermore, simultaneous measurements of hydroperoxy-radicals (HO2) are needed to assist the interpretation of chemistry. The OH-radicals are sampled by fast gas-expansion of ambient air into a low pressure fluorescence chamber and are detected by laser-induced fluorescence (LIF) using the excitation wavelength 308 nm. A high-repetition rate laser system will be used to give adequate sensitivity (105 OH/cm3 in a few minutes). This technique is essentially free from interferences by laser generated OH. The nearly simultaneous measurement is achieved by chemical conversion of atmospheric HO2 into OH by titration with NO. The high-repetition rate laser system to be used in this project will be a combination of an optimized copper vapour laser (CVL) and a small-bandwidth tunable dye laser that will be modified and optimized for reliable field operation. The laser system will be integrated into an existing LIF experiment which will be developed into an operative mobile field instrument for ground based measurements. The instrument will be tested during a comprehensive photochemistry field campaign at Juelich. In a second part of this project, a novel concept for a tunable CVL-pumped Ti doped sapphire laser will be studied for use as a compact and lightweight laser radiation source, designed for an advanced OH/HO2 measurement system that could be operated on board of a small airplane.
Types:
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Jülich ? Fluoreszenz ? Farbstofflaser ? Messgerät ? Messstation ? Kupfer ? Brüden ? Laser ? Messeinrichtung ? Photochemie ? Spurengas ? Außenluft ? Motorflugzeug ? Titration ? Strahlung ? In-Situ-Messung ? Oxidation ? Troposphäre ? Atmosphärenchemie ? Forschungseinrichtung ? in situ ? Anlagenbetrieb ? Geosphäre ? Laseranwendung ? Auflösungsvermögen ? CVL ? Hydroxylradikal ? Konzentrationsmessung ? LIF ? Radikal [Chemie] ?
Region: Nordrhein-Westfalen
Bounding box: 6.76339° .. 6.76339° x 51.21895° .. 51.21895°
License: cc-by-nc-nd/4.0
Language: Deutsch
Time ranges: 1992-12-01 - 1994-11-30
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