Auflistung nach Autor:in "Naumann, Karl-Heinz"

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Carbon mass determinations during the AIDA soot aerosol campaign 1999
(Elsevier, 10/2003) Saathoff, Harald; Naumann, Karl-Heinz; Schnaiter, Martin; Schöck, Werner; Weingartner, Ernest; Baltensperger, Urs; Krämer, Lutz; Bozoki, Zoltan; Pöschl, Ulrich; Niessner, Reinhard; Schurath, Ulrich
During the soot aerosol campaign particle carbon mass concentrations of Diesel soot, spark generated “Palas” soot, external and internal mixtures of Diesel soot with (NH4)2SO4, and particles coated with secondary organic aerosol material were determined by several different methods. Two methods were based on thermochemical filter analysis with coulometric and NDIR detection of evolved CO2 (total carbon, TC and elemental carbon, EC) and four methods employed optical techniques: aethalometry (black carbon, BC), photoacoustic soot detection (BC), photoelectron emission, and extinction measurement at 473 nm. Furthermore, β-attenuation (total particulate mass), FTIR spectroscopy (sulphate), and COSIMA model calculations were used to determine particle mass concentrations. The general agreement between most methods was good although some methods did not reach their usual performance. TC determined by coulometric filter analysis showed good correlations with optical extinction, photoacoustic BC signal, and photoelectron emission data. However, the evolution of the photoelectron emission signal correlated with changes in accessible surface area rather than mass concentration and was very sensitive to surface conditions. The BC content as measured by the aethalometers approximately equal to less than 70% of the EC content for Diesel soot and amounts to less than 25% of the EC content of “Palas” soot.
01A - Beitrag in wissenschaftlicher Zeitschrift
Coating of soot and (NH4)2SO4 particles by ozonolysis products of α-pinene
(Elsevier, 10/2003) Saathoff, Harald; Naumann, Karl-Heinz; Schnaiter, Martin; Schöck, Werner; Möhler, Ottmar; Schurath, Ulrich; Weingartner, Ernest; Gysel, Martin; Baltensperger, Urs
The ozonolysis of α-pinene in a large aerosol chamber was used to generate secondary organic aerosol (SOA) mass by homogeneous nucleation, or by heterogeneous nucleation, either on soot, or on (NH4)2SO4 seed aerosols. The rate of the α-pinene + ozone reaction and the aerosol yield of ∼19% are in good agreement with literature data. The organic coating of soot particles leads to a compaction of the fractal agglomerates expressed by an increase in fractal dimension from 1.9 to 2.1 for Diesel soot, and from 2.0 to 2.3 for spark generated “Palas” soot. The dielectric coating of the soot particles with SOA layers between 2 to 11 nm gives rise to a substantial enhancement of their single scattering albedo, from about 0.2 to 0.5, and increases the effective absorption coefficients of both soot types by ca. 30%. The coating of both soot types increases the hygroscopic growth factors (HGF) to values close below the HGF measured for pure SOA material d/d0∼1:12 at 90% RH.
01A - Beitrag in wissenschaftlicher Zeitschrift