Abstract Laser-induced fluorescence (LIF) technique has been widely applied in PAH measurement in sooting flames, but it is still a big challenge to quantitatively identify the specific PAH species due to the complexities of spectral characteristics and calibration method. In this study, we aimed at developing a spectral-resolved LIF analytic model that can obtain PAH mole fractions in flames. A comprehensive LIF spectrum database in the wide temperature and concentration ranges was firstly established by the LIF experiments of gas-phase PAHs in an optical cell. Then, a spectral-resolved LIF analytic model was presented based on linear superposition regulation and an optimization fitting algorithm, and the LIF spectra of PAH components can be decomposed from the LIF spectra of the flame using this model. Finally, the integral fluorescence intensities of each PAH component were calibrated to their mole fractions by the calibration factors at corresponding temperatures. In this way, we can measure the mole fractions of several PAHs. Subsequently, the presented LIF method was applied to investigate the PAH formation characteristics at different flame temperatures. The experimental results showed that the mole fractions of each PAH except naphthalene decreased around 60% to 70% when the temperature increased from 1186 K to 1483 K, while the mole fraction of naphthalene kept nearly constant. The mole fractions simulated by a chemical kinetic model well reproduce the experimental results. According to the chemical kinetic analysis, C2H2 oxidation reaction was promoted and the C2H2-addition reactions were suppressed by increasing temperatures, which suppressed the PAH formation.

中文翻译：

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用于选择性和定量测量层流预混火焰中多环芳烃的 LIF 诊断

摘要 激光诱导荧光（LIF）技术已广泛应用于烟尘火焰中多环芳烃的测量，但由于光谱特征和校准方法的复杂性，定量识别特定的多环芳烃物种仍然是一个很大的挑战。在本研究中，我们旨在开发一种光谱分辨 LIF 分析模型，该模型可以获得火焰中的 PAH 摩尔分数。通过光学池中气相多环芳烃的 LIF 实验，首次建立了宽温度和浓度范围内的综合 LIF 光谱数据库。然后，提出了基于线性叠加调节和优化拟合算法的光谱分辨LIF解析模型，使用该模型可以从火焰的LIF光谱中分解PAH组分的LIF光谱。最后，每个 PAH 组分的积分荧光强度通过相应温度下的校准因子校准到它们的摩尔分数。通过这种方式，我们可以测量几种多环芳烃的摩尔分数。随后，提出的 LIF 方法用于研究不同火焰温度下 PAH 的形成特性。实验结果表明，当温度从 1186 K 升高到 1483 K 时，除萘之外的各 PAH 的摩尔分数降低了 60% 到 70%，而萘的摩尔分数几乎保持不变。化学动力学模型模拟的摩尔分数很好地再现了实验结果。根据化学动力学分析，升高温度促进了 C2H2 氧化反应，抑制了 C2H2 加成反应，