Laser-induced incandescence (2λ and 2C) for estimating absorption efficiency of differently matured soot

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Two-wavelength and two-color laser-induced incandescence (2λ–2C-LII) was used to study the absorption properties of three types of cold soot of different maturity from a mini-CAST soot generator. LII fluence curve analysis allowed for estimating absorption wavelength dependence in terms of dispersion coefficients ξ by the use of two excitation wavelengths (532 and 1064 nm). The estimated ξ (based on E(m, λ) ∝ λ1−ξ) spanned from ~ 1.2 for the mature soot, up to 2.3 for the young soot. The results for the mature soot showed good agreement with previous measurement using multi-wavelength extinction. For the young soot, however, some discrepancy was observed suggesting a weaker wavelength dependence (lower ξ) from the LII fluence analysis. Furthermore, an estimation of the E(m, λ) for the different types of soot was done from the experimental fluence curves with temperature analysis in the low-fluence regime and simulations using an LII model. Additionally, uncertainties and limitations were discussed. Finally, it should be pointed out that caution has to be taken when interpreting 2λ-LII results to obtain quantitative absorption properties of less mature soot, which may be influenced by thermal annealing during the laser pulse and by absorption from non-refractory species externally/internally mixed with the soot.


Enheter & grupper

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Atom- och molekylfysik och optik
TidskriftApplied Physics B: Lasers and Optics
Utgåva nummer7
StatusPublished - 2021 jul 1
Peer review utfördJa

Relaterad forskningsoutput

Sandra Török, 2021 aug 24, Department of Physics, Lund University. 88 s.

Forskningsoutput: AvhandlingDoktorsavhandling (sammanläggning)

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