313 research outputs found
Radicals in the Atmosphere: A Changing World!
No full textGeorge, Christian Behnke, Wolfgang Zetzsch, Corneliu
Nachweis von atmosphärischem NO im ppb-Bereich mittels Fluoreszenzanregung durch NO-[gamma]-Banden
No full textKohse-Höinghaus K, Biermann HW, Zetzsch C, Stuhl F. Nachweis von atmosphärischem NO im ppb-Bereich mittels Fluoreszenzanregung durch NO-[gamma]-Banden. Zeitschrift für Naturforschung, A: Physical Sciences. 1976;31:239-243
Detection of NH (X3 [Sigma]-) by resonance fluorescence in the pulsed vacuum UV photolysis of NH3 and its application to reactions of NH radicals
No full textHansen I, Kohse-Höinghaus K, Zetzsch C, Stuhl F. Detection of NH (X3 [Sigma]-) by resonance fluorescence in the pulsed vacuum UV photolysis of NH3 and its application to reactions of NH radicals. Chemical Physics Letters. 1976;42(2):370-372.Using resonance fluorescence the kinetics of NH (X3 [Sigma]-) was studied in the pulsed vacuum UV photolysis of mixtures of NH3 and NO. The rate constant of the reaction NH + NO was determined to be (4.7 = 1.2) x lO - 11 cm 3 molecule - 1 s -
Kinetic mechanism for the formation of ClNO2 from the reaction of gaseous N2O5 with NaCl solution
No full textS.489-493The uptake of N2O5 by moist NaCl aerosol has been shown to lead to the formation of ClNO2 and HNO3 in smog chamber experiments. Model calculations indicate that the formation of ClNO2 may be an important source of atomic Cl under the tropospheric conditions of the high northern latitudes (Zetzsch and Behnke, 1992). Halogen atoms (Cl and Br) may also be the cause of tropospheric ozone degradation during the arctic spring (Barrie et al., 1988; Sturges and Shaw, 1993; Jobson et al., 1994). Here we present results from wetted-wall flowtube experiments at various concentrations of NaCl and NaNO3. The yield of ClNO2 after N2O5 injection as well as the uptake of ClNO2 are measured at 18+-0.5 degrees C
Mass accommodation: Uptake coefficients of N2O5 on pure water and on NaCl containing droplets. A contribution to subproject HALIPP
No full textS.1090-1095Dinitrogen pentoxide (N2O5) is an important constituent in the atmosphere. It plays the role of a night-time reservoir of NO3 radicals. The heterogeneous reactions of N2O5 with aqueous aerosols may convert this reservoir to HNO3 (that is photolysed only slowly in the troposphere). This heterogeneous sink of N2O5 is believed to terminate the reaction cycle of NOx, mainly responsible for the formation of tropospheric ozone. Recently, it has been shown that N2O5 may also react with NaCl salt to form nitryl chloride (ClNO2), a photolytic precursor of the highly reactive atomic chlorine. Behnke and Zetzsch showed that nitryl chloride is also formed in deliquescent aqueous aerosols and even in dilute solutions. With regard to these observations, it appears important to understand the efficiency of the heterogeneous reactions of N2O5 with aqueous surfaces. Therefore, we studied the uptake of N2O5 by water and NaCl solution (at 1 mol/l) using the droplet train technique
UV-Spektren und Druckverbreiterung von SO2, CH2O und CS2
No full textAbsolute and differential absorption cross sections were determined with a cw-dye ring laser (1) to obtain fully resolved molecular spectra. The spectral range of our present experiments covered the important region of the OH-radical absorption around 308 nm (250 GHz range). The many-line spectra and the absorption coefficents of SO2, CH2O and CS2 were investigated. In addition, the pressure broadening of these gases was determined in the range from a pure Doppler broadened spectrum up to atmospheric pressure. The broadening parameter was determined by comparing the broadened spectra with the convolution of the low pressure spectra with a Lorentz function. In addition, the temperature dependance of the SO2 spectrum is determind from room temperature down to minus 70 degree C for a decrease of overlapping spectral structures. These data can be used as reference in long path DOAS experiments to determine tropospheric trace gas concentrations
Time Resolved Infrared Spectroscopy of Formation and Processing of Secondary Organic Aerosol
No full textAbstract
An aerosol flow reactor was coupled to an infrared absorption cell to study aerosol formation processes with high temporal resolution. The recorded infrared spectra were referenced using aerosol smog chamber experiments. Evaluation was done by studying the formation of secondary organic aerosol from α-pinene and catechol as precursors and ozone as oxidant. Three main infrared absorptions: ν(O-H), ν(C-H) and ν(C=O) were considered, and humic like properties of the secondary organic aerosol are mainly interpreted according to the formation and variations of carbonyl bands in the region between 1850 and 1600 cm−1, especially the ν(C=O) of aryl carbonyls from catechol oxidation products below 1700 cm−1. The relative intensities of two major ν(C=O) stretching vibrations at 1690 cm−1 and 1755 cm−1 were observed to depend strongly on the available ozone concentration. At high precursor/ozone ratios (2:1 or 1:1) the vibration at 1690 cm−1 predominates, indicating aryl carbonyl vibrations. With increasing ozone concentrations this vibration is replaced by the higher carbonyl vibration at 1755 cm−1 indicating unsaturated carbonyl-containing compounds. This is a strong hint at ring opening processes leading to unsaturated aliphatic compounds in the resulting particle. Aryl carbonyls and aromatic or olefinic ν(C=C) at 1620 cm−1 in aged particles remain visible, as aerosol smog chamber studies exhibit – thus a strong hint at humic like properties of the SOA from the spectroscopic point of view.</jats:p
New bands of the transitions (c1Π → a1Δ) and (c1Π → b1Σ+) of NH and ND: the predissociation of NH (c1σ)
No full textChemikalienabbau in der Atmosphäre - Einfluß von Staub im Sonnenlicht
No full textS.23-47Fuer die angewandte Forschung hat das Projekt fuer einen Kunststoff-Weichmacher an verschiedenen Luftstaeuben die obere Grenze der Aufenthaltsdauer in der Atmosphaere ergeben, darueber hinaus wurden mehr als 30 fluechtige Chemikalien auf ihr Abbauverhalten in An- und Abwesenheit von Staeuben untersucht. In der Grundlagenforschung hat das Projekt neue, groesstenteils unerwartete Abbauwege von Luftverunreinigungen aufgezeigt, deren Mechanismen plausibel gemacht werden koennen. Eine quantitative Bestimmung des Anteils der beobachteten Abbauprozesse am gesamten abiotischen Abbau in der Luft steht noch aus. (ITA
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