Calibration of a Single-Particle Soot Photometer with Different Soot Surrogates

JAMES HENRY, Dongli Wang, Andrew Metcalf, Clemson University

     Abstract Number: 604
     Working Group: Instrumentation and Methods

Abstract
The Single Particle Soot Photometer (SP2) uses a high-powered laser to heat absorbing aerosol particles, including black carbon, to the point of incandescence. The energy given off as incandescence can then be used to determine the mass of individual particles present in the air sample. To determine the bulk mass or number concentration of particles in the air, these individual particles are added together. Thus, any errors or uncertainties in the single-particle data can compound to give larger errors in the derived bulk concentrations. Therefore, careful calibration with the proper material(s) is required to ensure accurate data from the SP2 instrument.

The purpose of this study is to determine the best calibration method(s) and material(s) for the SP2. Because materials and chemicals available previously are no longer available from the same manufacturers, data from several black carbon surrogates (i.e., fullerenes) that are currently available are used to determine whether different chemical structures (e.g., C60 and C70 at different levels of purity) lead to distinct incandescence signals that would change the SP2 calibration factors. The data analysis procedures are also examined in detail to determine if the peak height detection in the raw signals may mask additional information on single-particle chemical structure.