Soot Particle Studies—Instrument Inter-Comparison—Project Overview

Abstract

An inter-comparison study of instruments designed to measure the microphysical and optical properties of soot particles was completed. The following mass-based instruments were tested: Couette Centrifugal Particle Mass Analyzer (CPMA), Time-of-Flight Aerosol Mass Spectrometer—Scanning Mobility Particle Sizer (AMS-SMPS), Single Particle Soot Photometer (SP2), Soot Particle-Aerosol Mass Spectrometer (SP-AMS) and Photoelectric Aerosol Sensor (PAS2000CE). Optical instruments measured absorption (photoacoustic, interferometric, and filter-based), scattering (in situ), and extinction (light attenuation within an optical cavity). The study covered an experimental matrix consisting of 318 runs that systematically tested the performance of instruments across a range of parameters including: fuel equivalence ratio (1.8 ≤ φ ≤ 5), particle shape (mass-mobility exponent ( D _fm ), 2.0 ≤ D _fm ≤ 3.0), particle mobility size (30 ≤ d _m ≤ 300 nm), black carbon mass (0.07 ≤ m _BC ≤ 4.2 fg) and particle chemical composition. In selected runs, particles were coated with sulfuric acid or dioctyl sebacate (DOS) (0.5 ≤ Δ r _ve ≤ 201 nm) where Δ r _ve is the change in the volume equivalent radius due to the coating material. The effect of non-absorbing coatings on instrument response was determined. Changes in the morphology of fractal soot particles were monitored during coating and denuding processes and the effect of particle shape on instrument response was determined. The combination of optical and mass based measurements was used to determine the mass specific absorption coefficient for denuded soot particles. The single scattering albedo of the particles was also measured. An overview of the experiments and sample results are presented.

Acknowledgments

This research was supported by the Office of Science (BER), Department of Energy (Atmospheric Science Program) grant No. DE-FG02-05ER63995 and the Atmospheric Chemistry Program of the National Science Foundation grants No. ATM-0525355 and ATM-0854916 to Boston College and Aerodyne Research, Inc. NOAA SP2 participation was supported by the NOAA Atmospheric Composition and Climate, and Health of the Atmosphere Programs, and the NASA Radiation Sciences Program and Upper Atmosphere Research Program. J. Olfert would like to thank Cambustion Ltd. for lending the Couette CPMA for this study. J. Olfert acknowledges the Goldhaber Distinguished Fellowship Program for providing funding for this project. C. Mazzoleni would like to thank MTU for start-up funds for SEM analysis and Owen P. Mills and Claire F. Drom at the Applied Chemical and Morphological Analysis Laboratory for their support.

[Supplementary materials are available for this article. Go to the publisher's online edition of Aerosol Science and Technology to view the free supplementary files.]

Notes

^a Results not included in the present article and will be presented in subsequent publications.

^a Results not included in the present article and will be presented in subsequent publications.

^a Results not included in the current article and will be presented in subsequent publications.