Department of Physics and Atmospheric Sciences Program, Michigan Technological University, Houghton, MI, 49931, USA
Abstract. The optical properties (light scattering and absorption) of soot particles depend on soot size and index of refraction, but also on the soot complex morphology and the internal mixing with other material at the single particle level. For example, freshly emitted (nascent) soot particles can interact with other materials in the atmosphere, materials that can condense on soot and coat it. This coating can affect the soot optical properties by refracting light, or by changing the soot aggregate structure. A common approach to studying the effect of coating on soot optical properties is to measure absorption and scattering values in ambient air and then measure them again after removing the coating using a thermodenuder. In this approach, it is assumed that: 1) Most of the coating material is removed; 2) charred organic coating does not add to the refractory carbon; 3) oxidation of soot is negligible; and 4) the pre-existing core soot structure is left unaltered despite potential oxidation of the core at elevated temperature. In this study, we investigate the validity of the last assumption, by studying the effect of thermodenuding on the structure of nascent soot. To this end, we analyze the morphological properties of laboratory generated nascent soot, before and after thermodenuding. Our investigation shows that there is only minor restructuring of nascent soot by thermodenuding.
How to cite. Bhandari, J., China, S., Onasch, T., Wolff, L., Lambe, A., Davidovits, P., Cross, E., Ahern, A., Olfert, J., Dubey, M., and Mazzoleni, C.: Effect of thermodenuding on the structure of nascent flame soot aggregates, Atmos. Meas. Tech. Discuss. [preprint], https://doi.org/10.5194/amt-2016-270, 2016.
Received: 23 Aug 2016 – Discussion started: 22 Nov 2016
Soot particles emitted during the incomplete burning activities, absorb solar radiation and contribute to global warming. Light absorption by soot is also affected by its structure. To investigate whether the soot particle changes its structure or not, we used thermodenuding technique in which soot particles were passed through a heated tube (275 0C). Our study found only minor restructuring of soot suggesting no significant biases in absorption by the modification of soot structure alone.
Soot particles emitted during the incomplete burning activities, absorb solar radiation and...