Measured In-situ Mass Absorption Spectra for Nine Forms of Highly-absorbing Carbonaceous Aerosol
Christopher D. Zangmeister, Rian You, Elizabeth M. Lunny, Arne Jacobson, Mitchio Okumura, Michael R. Zachariah, James G. Radney
Mass absorption coefficient spectra were measured between λ = 500 nm and 840 nm for nine forms of highly-absorbing carbonaceous aerosol: five samples generated from gas-, liquid- and solid- fueled flames; spark-discharge fullerene soot; graphene and reduced graphene oxide (rGO) crumpled nanosheets; and fullerene (C60) assemblies. Aerosol absorption spectra were measured for size- and mass-selected particles and found to be dependent on fuel type and formative conditions. Flame-generated particles had morphologies consistent with freshly emitted black carbon (BC) with mass absorption coefficients (MAC) ranging between 3.8 m2 g-1 and 8.6 m2 g-1 at λ = 550 nm. Absorption Ångström exponents (AAE) i.e. MAC spectral dependence ranged between 1.0 and 1.3 for flame-generated particles and up to 7.5 for C60. The dependence of MAC and AAE on mobility diameter and particle morphology was also investigated. Lastly, the current data were compared to all previously published MAC measurements of highly-absorbing carbonaceous aerosol.