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Flame soot characterization using combined multi-wavelength thermo-optical analysis and Raman spectroscopy

Bergqvist, Saga LU ; Rex, Johannes LU ; Kaarna, Amanda ; Lynghed, Hanne ; Le, Kim Cuong LU orcid ; Eriksson, Axel C. LU orcid ; Pagels, Joakim LU and Bengtsson, Per Erik LU orcid (2026) In Aerosol Science and Technology 60(2). p.135-151
Abstract

Multi-wavelength thermo-optical analysis (MW-TOA) and Raman spectroscopy are commonly used methods to study soot sampled on filters, in terms of carbon content, nanostructure, and absorption properties. In this work, these techniques were combined to study how these characteristic properties of soot change in premixed flames, 1) at various flame heights during soot maturation and 2) as a result of potassium addition to the fuel. It was found from MW-TOA that sampled soot showed decreasing organic carbon (OC) fraction and increasing elemental carbon (EC) fraction with flame height. During heat treatment, light absorption increased significantly in the immature sampled soot. Soot from all sampling heights reached similar MAC values at the... (More)

Multi-wavelength thermo-optical analysis (MW-TOA) and Raman spectroscopy are commonly used methods to study soot sampled on filters, in terms of carbon content, nanostructure, and absorption properties. In this work, these techniques were combined to study how these characteristic properties of soot change in premixed flames, 1) at various flame heights during soot maturation and 2) as a result of potassium addition to the fuel. It was found from MW-TOA that sampled soot showed decreasing organic carbon (OC) fraction and increasing elemental carbon (EC) fraction with flame height. During heat treatment, light absorption increased significantly in the immature sampled soot. Soot from all sampling heights reached similar MAC values at the end of the inert heating stage. In the immature soot, the initially high absorption Ångström exponent (AAE) decreased significantly during heat treatment in MW-TOA due to evaporation of volatile OC and through carbonization, while in the mature soot the initially low AAE changed negligibly during heat treatment. Potassium (K) addition to the fuel/air-mixture resulted in lower soot absorption, lower EC fraction, a strong reduction of the nucleation size mode and a shift of the accumulation size mode toward smaller sizes. Despite the clear changes in soot properties from MW-TOA, Raman spectroscopic analysis showed relatively small differences with K addition.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Aerosol Science and Technology
volume
60
issue
2
pages
17 pages
publisher
Taylor & Francis
external identifiers
  • scopus:105020804111
ISSN
0278-6826
DOI
10.1080/02786826.2025.2576897
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 The Author(s). Published with license by Taylor & Francis Group, LLC.
id
1de26a84-53bf-43a9-99e4-5dc99c4862a2
date added to LUP
2026-01-14 09:51:28
date last changed
2026-01-14 09:52:40
@article{1de26a84-53bf-43a9-99e4-5dc99c4862a2,
  abstract     = {{<p>Multi-wavelength thermo-optical analysis (MW-TOA) and Raman spectroscopy are commonly used methods to study soot sampled on filters, in terms of carbon content, nanostructure, and absorption properties. In this work, these techniques were combined to study how these characteristic properties of soot change in premixed flames, 1) at various flame heights during soot maturation and 2) as a result of potassium addition to the fuel. It was found from MW-TOA that sampled soot showed decreasing organic carbon (OC) fraction and increasing elemental carbon (EC) fraction with flame height. During heat treatment, light absorption increased significantly in the immature sampled soot. Soot from all sampling heights reached similar MAC values at the end of the inert heating stage. In the immature soot, the initially high absorption Ångström exponent (AAE) decreased significantly during heat treatment in MW-TOA due to evaporation of volatile OC and through carbonization, while in the mature soot the initially low AAE changed negligibly during heat treatment. Potassium (K) addition to the fuel/air-mixture resulted in lower soot absorption, lower EC fraction, a strong reduction of the nucleation size mode and a shift of the accumulation size mode toward smaller sizes. Despite the clear changes in soot properties from MW-TOA, Raman spectroscopic analysis showed relatively small differences with K addition.</p>}},
  author       = {{Bergqvist, Saga and Rex, Johannes and Kaarna, Amanda and Lynghed, Hanne and Le, Kim Cuong and Eriksson, Axel C. and Pagels, Joakim and Bengtsson, Per Erik}},
  issn         = {{0278-6826}},
  language     = {{eng}},
  number       = {{2}},
  pages        = {{135--151}},
  publisher    = {{Taylor & Francis}},
  series       = {{Aerosol Science and Technology}},
  title        = {{Flame soot characterization using combined multi-wavelength thermo-optical analysis and Raman spectroscopy}},
  url          = {{http://dx.doi.org/10.1080/02786826.2025.2576897}},
  doi          = {{10.1080/02786826.2025.2576897}},
  volume       = {{60}},
  year         = {{2026}},
}