Quantification of online removal of refractory black carbon using laser-induced incandescence in the single particle soot photometer

For the mobility-selected samples, the average percentages removed by mass and number of the original size are 88.9 ± 18.6% and 87.3 ± 21.9%, respectively. Removal of Aquadag is efficient for particles >100 nm mass-equivalent diameter ( d me ), enabling application for microphysical studies. However, the removal of particles ≤100 nm d me is less efficient.

Absorption and scattering measurements are reported to assess its use to isolate brown carbon (BrC) absorption. Scattering removal rates for the mobility-selected samples are >90% on average, yet absorption rates are 53% on average across all wavelengths. Therefore, application to isolate effects of microphysical properties determined by larger sizes is promising, but will be challenging for optical properties.

The results reported also have implications for other instruments employing internal LII, e.g., the Soot Particle Aerosol Mass Spectrometer (SP-AMS). © 2016 American Association for Aerosol Research