Nanostructure Transition of Young Soot Aggregates to Mature Soot Aggregates in Diluted Diffusion Flames.

In this study, the structural properties of soot produced in diffusion flames are analyzed to elucidate the formation of mature aggregates from large young particles. Soot samples are generated in a laminar diffusion inverted gravity flame reactor (IGFR) operated on methane, ethane, and ethylene with Ar dilution to reduce the flame temperature. Soot produced in temperature ranges from 1495K-1568 K contains 100nm-300nm particles with (i) isotropic or (ii) multiple core structures, supporting a soot maturation pathway where one young soot particle evolves into a mature fractal aggregate via an internal nucleation route.

Excitation-Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter.

Analysis of particulate matter (PM) is important for the assessment of human exposures to potentially harmful agents, notably combustion-generated PM. Specifically, polycyclic aromatic hydrocarbons (PAHs) found in ultrafine PM have been linked to cardiovascular diseases and carcinogenic and mutagenic effects. In this study, we quantify the presence and concentrations of PAHs with lower molecular weight (LMW, 126 < MW < 202) and higher molecular weight (HMW, 226 < MW < 302), i.