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  • Abiotic degradability  (1)
  • chemiluminescence  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of atmospheric chemistry 14 (1992), S. 73-84 
    ISSN: 1573-0662
    Schlagwort(e): Ozone sensor ; chemiluminescence ; eddy correlation ; eddy flux ; dry deposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract A small, lightweight (1.5 kg) and fast-response ozone sensor for direct eddy flux measurements has been built. The basis for detection is the chemiluminescence of an organic dye adsorbed on dry silica gel in the reaction with ozone. The chemiluminescence is monitored with a cheap and small blue-sensitive photomultiplier. At a flow rate of 100 l min-1 the ozone sensor has a 90% response time of significantly better than 0.1 s with a detection limit lower than 50 ppt at S/N=3. There are no interferences from other atmospheric trace gases like NOx, H2O2 and PAN. Water vapour and SO2 enhance the chemiluminescence efficiency of the ozone sensor. Since their response times are 22 seconds and 30 minutes, respectively, no correlation between rapid ozone fluctuations and those of these two trace gases is noticed by the ozone sensor when operating at a frequency of 10 Hz. The ozone sensor was tested for several weeks in continuous measurements of ozone fluxes and deposition velocities over different croplands using the eddy correlation technique. Good agreement was found between ozone dry deposition velocities derived from profile measurements and by eddy correlation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of atmospheric chemistry 2 (1984), S. 83-93 
    ISSN: 1573-0662
    Schlagwort(e): Abiotic degradability ; vertical ionisation energy ; reaction rate constant ; OH radical reactivity ; tropospheric lifetime ; organic compounds ; environmental chemicals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract A statistically relevant correlation between the reaction rate coefficient, k OH, for the OH radical reaction with 161 organic compounds in the gas phase at 300 K, and the corresponding vertical ionisation energies E i,v, reveals two classes of compounds: aromatics where −log(k OH/cm3s-1)≃3/2E i,v(eV)−2 and aliphatics where −log(k OH/cm3s-1)≃4/5E i,v(eV)+3. The prediction of the rate coefficient, k OH, for the reaction of OH with organic molecules from the above equations has a probability of about 90%. Assuming a global diurnal mean of the OH radical concentration of 5×105 cm3, the upper limit of the tropospheric half-life of organic compounds and their persistence can be estimated.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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