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) ∝ λ^1−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.

双波长双色激光诱导白炽度 (2 λ –2C-LII) 用于研究来自 mini-CAST 烟尘发生器的三种不同成熟度的冷烟尘的吸收特性。LII 通量曲线分析允许通过使用两个激发波长（532 和 1064 nm）根据色散系数ξ估计吸收波长的依赖性。估计的ξ（基于E ( m, λ ) ∝  λ ^1−ξ) 从成熟烟灰的 ~ 1.2 到年轻烟灰的 2.3 跨越。成熟烟灰的结果与之前使用多波长消光的测量结果非常吻合。然而，对于年轻的烟灰，观察到一些差异，表明来自 LII 能量密度分析的波长依赖性较弱（较低的ξ）。此外，对不同类型烟尘的E ( m, λ )的估计是根据实验通量曲线与低通量状态下的温度分析和使用 LII 模型的模拟进行的。此外，还讨论了不确定性和局限性。最后，应该指出的是，在解释 2 λ时必须谨慎-LII 的结果是获得不太成熟的烟灰的定量吸收特性，这可能会受到激光脉冲期间的热退火和外部/内部与烟灰混合的非难熔物质的吸收的影响。