Abstract. We have developed a novel single-beam photothermal interferometer and present here its application for the measurement of aerosol light absorption. The use of only a single laser beam allows for a compact optical set-up and significantly easier alignment compared to standard
dual-beam photothermal interferometers, making it ideal for field measurements. Due to a unique configuration of the reference interferometer arm, light absorption by aerosols can be determined directly – even in the presence of light-absorbing gases. The instrument can be calibrated directly with light-absorbing gases, such as NO2, and can be used to calibrate other light absorption instruments. The detection limits (1σ) for absorption for 10 and 60 s averaging times were determined to be 14.6 and 7.4 Mm−1, respectively, which for a mass absorption cross section of 10 m2 g−1 leads to equivalent black carbon concentration detection limits of 1460 and 740 ng m−3, respectively. The detection limit could be reduced further by improvements to the isolation of the instrument and the signal detection and processing schemes employed.
Abstract. We report on an inter-comparison of black-carbon- and
aerosol-absorption-measuring instruments with laboratory-generated soot
particles coated with controlled amounts of secondary organic matter (SOM).
The aerosol generation setup consisted of a miniCAST 5201 Type BC burner for
the generation of soot particles and a new automated oxidation flow reactor
based on the micro smog chamber (MSC) for the generation of SOM from the
ozonolysis of α-pinene. A series of test aerosols was generated with elemental to total carbon (EC / TC) mass fraction ranging from about 90 % down to 10 % and single-scattering albedo (SSA at 637 nm) from almost 0 to about 0.7. A dual-spot Aethalometer AE33, a photoacoustic extinctiometer
(PAX, 870 nm), a multi-angle absorption photometer (MAAP), a prototype
photoacoustic instrument, and two prototype photo-thermal interferometers
(PTAAM-2λ and MSPTI) were exposed to the test aerosols in parallel.
Significant deviations in the response of the instruments were observed
depending on the amount of secondary organic coating. We believe that the
setup and methodology described in this study can easily be standardised and provide a straightforward and reproducible procedure for the
inter-comparison and characterisation of both filter-based and in situ black-carbon-measuring
(BC-measuring) instruments based on realistic test aerosols.
zum 65. Geburtstage gewidmet Die Herstellung von porösen geträgerten Katalysatoren mit fein einstellbaren Struktureigenschaften spielt in der heterogenen Katalyse eine große Rolle in der Erforschung von Reaktionsabläufen und Mechanismen. Das Zusammenspiel von nanoskaligen Poren und Aktivkomponenten bietet dabei die Möglichkeit der Optimierung von Reaktionen im Hinblick auf Ausbeute und Selektivität. Gängige Synthesemethoden sind oftmals in der Variationsbreite limitiert. Im Rahmen dieser Arbeit wird ein einfacher und gut skalierbarer Aerosol-Syntheseweg für die Herstellung nanoskaliger Katalysatoren für die Fischer-Tropsch-Synthese aufgezeigt.The production of porous and supported catalysts with precisely tunable structural properties plays an important role in heterogeneous catalysis regarding the exploration of reaction paths and mechanisms. The interaction of nano-scale pores and active components offers the unique possibility to optimize reactions towards yield and. Common synthesis routes are often limited within their variability. Therefore, a new and scalable aerosol-based synthesis route is presented in this work to overcome these issues and to vary pore sizes and active metal particle sizes independently.
Abstract. We report on an inter-comparison of black carbon and aerosol absorption measuring instruments with laboratory-generated soot particles coated with controlled amounts of secondary organic matter (SOM). The aerosol generation setup consisted of a miniCAST 5201 Type BC burner for the generation of soot particles and a new automated oxidation flow reactor based on the micro smog chamber (MSC) for the generation of SOM from the ozonolysis of α-pinene. A series of test aerosols were generated with elemental to total carbon (EC/TC) mass fraction ranging from about 90 % down to 10 % and single scattering albedo (SSA) from almost 0 to about 0.7. A dual-spot aethalometer AE33, a photoacoustic extinctiometer (PAX, 870 nm), a multi-angle absorption photometer (MAAP), a prototype photoacoustic instrument and two prototype photo-thermal interferometers (PTAAM-2λ and MSPTI) were exposed to the test aerosols in parallel. Significant deviations in the response of the instruments were observed depending on the amount of secondary organic coating. We believe that the setup and methodology described in this study can easily be standardized and provide a straightforward and reproducible procedure for the inter-comparison and characterisation of both filter-based and in situ BC-measuring instruments based on realistic test aerosols.
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