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Detector Fabrication
Published in Alan Owens, Semiconductor Radiation Detectors, 2019
A simple and convenient method for forming contacts (especially when prototyping or testing) is to apply a conductive paint or paste onto the surface to be contacted. Silver paint is commonly used as well as Aquadag6 and derivatives such as Electrodag, which are colloidal dispersions of graphite and silver, respectively, in a carrier (water, in the case of Aquadag, and a fluoroelastomer resin in the case of Electrodag). All can be easily applied to most surfaces by conventional spray, brush or dip methods. However, while the applied films have good adhesion and low sheet resistance (<120 Ω/□), they are generally soft, making it difficult to attach wires without the use of a mechanical spring or conductive glue.
An inter-comparison of black-carbon-related instruments in a laboratory study of biomass burning aerosol
Published in Aerosol Science and Technology, 2018
Antonios Tasoglou, R. Subramanian, Spyros N. Pandis
Petzold et al. (2013) proposed a terminology for the BC based on the method used for its measurement. A number of commercial instruments (aethalometer, Photoacoustic Extinctiometer-PAX, Multiangle Absorption Photometer-MAAP, Particle Soot/Absorption Photometer-PSAP, Photoacoustic Soot Spectrometer-PASS, Photoacoustic Spectrometer-PAS, continuous soot monitoring system-COSMOS) for the measurement of BC mass calculate the equivalent BC (eBC) mass concentration by measuring the absorption coefficient (babs) of the particles. The aerosol mass absorption cross-section (MAC) is then used to convert the measured babs to the eBC mass concentration. Other instruments (Soot Particle Aerosol Mass Spectrometer-SP-AMS, Single-Particle Soot Photometer-SP2) measure the refractory BC (rBC) mass concentration by heating the particles with an infrared laser (Melton 1984; Stephens, Turner, and Sandberg 2003; Snelling et al. 2005; Schwarz et al. 2006; Chan et al. 2011). In the SP2 the BC-containing particles are heated to the point of incandescence and the incandescent light emission is measured. In the SP-AMS the BC-containing particles are vaporized with the use of a laser. The resulting vapor is ionized and the ions are detected by a high–resolution mass spectrometer (DeCarlo et al. 2006). These instruments are calibrated relating their signal to the rBC mass with the help of BC proxies like Aquadag (Aqueous Deflocculated Acheson Graphite, Achenson Inc.) or fullerene soot (Alfa Aesar) or regal black (REGAL 400 R pigment black Cabot Corp.). Thermal-optical analysis of filter-based samples to measure elemental carbon (EC) has been used for more than 50 years (Huntzicker et al. 1982; Watson et al. 2005; Subramanian, Khlystov, and Robinson 2006; Petzold et al. 2013) and will not be further considered in the present work.
Optical and morphological properties of soot particles generated by the miniCAST 5201 BC generator
Published in Aerosol Science and Technology, 2021
Michaela N. Ess, Michele Bertò, Martin Irwin, Robin L. Modini, Martin Gysel-Beer, Konstantina Vasilatou
The single-particle soot photometer (SP2, Droplet Measurement Technologies, Longmont, CO, USA) is an online single-particle instrument able to quantitatively retrieve the mass of the refractory black carbon particles (rBC; following the nomenclature suggested by Petzold et al. (2013). The SP2 is a well-characterized instrument relying on the LII technique. A complete description of the working principles and measuring performances of the SP2 can be found in (Moteki and Kondo 2007; Stephens, Turner, and Sandberg 2003; Schwarz et al. 2006; Laborde, Mertes, et al. 2012). Briefly, the instrument functions by drawing particles into the center of a Gaussian-profiled, continuous-wave Nd:YAG laser operating at a wavelength of 1064 nm. The rBC particles efficiently absorb the radiation at this wavelength and, as a consequence, are heated up to their sublimation temperature (approximately 4000 K), where they emit an incandescence signal before vaporizing. The incandescence signals from each particle are recorded by two detectors (photomultiplier tubes) equipped with band pass filters in the ranges 350–800 nm and 630–800 nm. The peak height intensity of an incandescence signal is proportional to the volume (and therefore the mass) of the incandescing rBC particle. In order to retrieve the particle mass from the incandescence signal intensity, the detectors have to be empirically calibrated using mass-selected particles. However, the SP2 incandescence signal to particle mass calibration relationship depends on the BC type. Generally, the most common calibration materials for atmospheric measurements are FS and AquaDAG (Aqueous Deflocculated Acheson Graphite from Acheson Inc., USA) particles: the former is specifically recommended since the SP2 showed a similar sensitivity between FS and diesel soot emissions (Baumgardner et al. 2012). Since miniCAST generated BC particles with different physical properties were measured in this study, the SP2 was calibrated via APM mass-selected particles of the specific miniCAST set point under investigation. The reproducibility of the SP2 was tested during an intense chamber inter-comparison for 6 SP2 units, resulting to be of 10% for the retrieval of BC mass size distributions (Laborde, Schnaiter, et al. 2012).