On imaging nascent soot by transmission electron microscopy

High-resolution Transmission Electron Microscopy (HRTEM) imaging of nascent soot was carried out with an emphasis in demonstrating the annealing of soot samples under continuous irradiation of the high-energy electron beam. Images were taken for several soot samples over the duration of 16 min in 2 min time intervals to reveal the crystallization process. Fringe properties, including fringe length, tortuosity, and spacing were analyzed over the duration of the imaging. The sensitivity of the fringe properties to the apparent changes in the nanostructures imaged was examined. The difficulties in quantifying soot composition and structures are further illustrated by analyzing simulated TEM images of molecular-dynamics generated particles. Together, the results highlight some of the challenges in using HRTEM to obtain unambiguous structural properties for nascent soot particles. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.