The SP2 is the only instrument in the world that directly measures the black carbon (soot) in individual aerosol particles. Its high sensitivity, fast response, and specificity to elemental carbon make it the premier instrument for characterizing air pollution sources and documenting thin, atmospheric layers of contamination. It is also ideal for measuring soot in snow, ice or water and for calibrating other black carbon-measuring instruments like the Aethalometer.
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Advantages:
• Measures black carbon (soot) mass in individual aerosol particles
• Uses Nd:YAG intracavity laser-induced particle incandescence (LII), a technique that measures black carbon mass independently of particle mixing state and hence yields more accurate results
• Detects black carbon mass at minute concentrations (below 10 ng/m3)
• Measures particle optical size using light-scattering
• Counts particles at concentrations up to 16,000 particles/sec (8,000 particles/cm3 at a sample flow rate of 120 volumetric cm3/minute)
• Provides full data recording of each particle event
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Customer Testimony:
“The unparalleled sensitivity of the SP2 has allowed us to investigate black carbon in the polar ice caps at a previously unimaginable temporal resolution. The instrument has opened up a whole new area of research with respect to black carbon in the Earth system.” — Ross Edwards, Senior Research Fellow, Curtin University of Technology, Perth, Australia
Applications:
• Pollution characterization
• Air quality and visibility
• Atmospheric and climate research
• Health effects studies
• Combustion emissions
• Biomass burning
Suitable for airborne or ground-based (fixed-site or mobile) sampling.
Photo at right: The SP2 being used for mobile air-quality tests conducted by the EPA in Durham, NC.
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Principle of Operation:
The SP2 uses the high optical power available intra-cavity from an Nd:YAG laser. Light-absorbing particles containing mainly black or elemental carbon absorb energy and are heated to the point of incandescence. The incandescent emission is measured and correlated to the particle’s black carbon mass with the help of black carbon proxies like Aquadag or fullerene soot.
The SP2 also includes a scattering detector, which detects single-particle light-scattering at 1064 nm. The scattering signal can be used to indicate particle size and the black carbon mixing state at the single-particle level. The scattering detector can also be used to detect non-BC-containing aerosol number and mass concentrations.
The full scattering and/or incandescence response of each particle is completely digitized for detailed analysis.
Calibration:
DMT recommends calibrating the SP2 every six months and/or before and after every field campaign.
• The incandescence measurement is calibrated to black carbon mass using DMA-sized Aquadag, fullerene soot or glassy carbon. (DMA refers to differential mobility analyzer, used to extract particles of a single electrical mobility size from a polydisperse aerosol.)
• The scattering measurement is calibrated to particle size using monodisperse polystyrene latex (PSL) spheres or DMA-sized ammonium sulfate.
DMT offers free software that automates much of the calibration process. The Probe Analysis Package for Igor (PAPI) assists the user in loading, consolidating, and analyzing calibration data files.
Software:
Standard SP2 Software
The SP2 comes with a software program that provides a user-friendly virtual instrument panel for the control, data display, and data logging of the SP2 instrument. For instance, the program enables the user to do the following tasks:
• View graphs of incandescence and scattering signals from individual particles
• View the incandescent particle concentration over the last 30 minutes
• Monitor parameters like YAG laser power and flow measurements
• Change the charts and data channels displayed in the software
• Filter data that is saved to the output file so it includes only specific types of particle events
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Probe Analysis Package for Igor (PAPI)
The SP2 also comes with a free copy of the Probe Analysis Package for Igor (PAPI). This program facilitates SP2 data analysis in several ways:
• Processing SP2 binary files and collecting particle-peak statistics
• Automating much of the SP2 calibration process
• Calculating common statistics such as black carbon mass and number concentrations, black carbon number fraction, and ensemble measurements
• Allowing user to select size bins with resolutions as fine as 5 nm (for both incandescent and scattering measurements)
• Providing journal-quality graphs and reports
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Accessories:
• Beam scan camera and software
• YAG optics kit (spare YAG crystal and output coupler)
• Laser alignment bench
• Nebulizer for liquid samples with optional auto-
sampler
• Aircraft Aerosol Inlet (see picture at left)
Left: Drawing of the Aircraft Aerosol Inlet
(Outer Shroud Translucent in Drawing so Insides are Visible)
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How to Order:
Contact DMT for pricing: +1.303.440.5576,
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Selected Bibliography:
• Stephens, M., N. Turner, and J. Sandberg, “Particle identification by laser-induced incandescence in a solid-state laser cavity,” Applied Optics, 42 (19), 3726-3736, 2003. link
• Slowik, J. G., E. S. Cross, J. -H. Han, P. Davidovits, T. B. Onasch, J. T. Jayne, L. R. Williams, M. R. Canagaratna, D. R. Worsnop, R. K. Chakrabarty, H. Moosmüller, W. P. Arnott, J. P. Schwarz, R. S. Gao, D. W. Fahey, G. L. Kok, and A. Petzold, “An inter-comparison of instruments measuring black carbon content of soot particles,” Aerosol Science and Technology, 41, 295-314, 2007. (1 Mar 2007) link
• Baumgardner, D., G. L. Kok, and G. B. Raga, “On the diurnal variability of particle properties related to light absorbing carbon in Mexico City,” Atmospheric Chemistry and Physics, 7, 2517-2526, 2007. (14 May 2007) PDF
• McConnell, J., R. Edwards, G. Kok, M. Flanner, C. Zender, E. Saltzman, J. Banta, D. Pasteris, M. Carter, J. Kahl, “20th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing,” Science, 317, 1381-1384, 2007. link
• Moteki, N., Y. Kondo, Y. Miyazaki, N. Takegawa, Y. Komazaki, G. Kurata, T. Shirai, D. R. Blake, T. Miyakawa, and M. Koike, “Evolution of the mixing state of black carbon particles: Aircraft measurements over the western Pacific in March 2004,” Geophysical Research Letters, 34, doi:10.1029/2006GL028943, 2007. link
• Subramanian, R., G. L. Kok, D. Baumgardner, A. Clarke, Y. Shinozuka, T. L. Campos, C. G. Heizer, and B. B. Stephens, “Black carbon over Mexico: the effect of atmospheric transport on mixing state, mass absorption cross-section, and BC/CO ratios,” Atmospheric Chemistry and Physics, 10, 219-237, 2010. (20 October 2009) PDF
Dr. Gavin McMeeking at the University of Manchester’s Center for Atmospheric Science maintains a comprehensive list of SP2-related publications.
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