AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Morphology and Internal Structure of Soot Carbon Characterized by Transmission Electron Microscopy and Raman Spectroscopy
RAMIN DASTANPOUR, Alberto Baldelli, Steven Rogak, University of British Columbia
Abstract Number: 367 Working Group: Combustion
Abstract Accurate measurement of the properties, emission rates, and environmental impacts (i.e. climate forcing) of black carbon particles depend on precise measurements of their composition, morphology, and internal structure.
This study investigates the morphology, internal structure, and graphitisation level of soot particles produced at different conditions with a combination of Transmission Electron Microscopy (TEM), High Resolution TEM (HRTEM), Raman Spectroscopy, and Surface Enhancement Raman Spectroscopy (SERS). Particles were collected at different operating conditions from an inverted diffusion burner and a lab-scale flare of up to 80 mm in diameter with turbulent flames up to 3 meter tall.
Size distributions of the soot particles and their constituting primary particles were measured by TEM. This method provides visual observation on the structure of individual soot particles and quantitative measurements are performed on the images produced. The internal structure of the particles was measured by HRTEM. An image processing program was developed to characterize the length, tortuosity, and spacing of the graphite layers (fringes). This method provides both qualitative and quantitative information on how graphitic or amorphous soot particles are.
Raman spectroscopy is a method commonly used for the analysis of various forms of carbons. This method was used in parallel to the HRTEM method to distinguish different types of soot by their degree of graphitization and to estimate the crystal sizes in disordered carbon. Due to a low collection rate, SERS was used to increase the Raman signal. This technique is used for the first time with flame-made carbon soot. Substrates of silver nanofibers are placed on the collection system generating an enhancement of the scattering signal in the order of 104.