A dual-frequency-comb spectrometer based on two quantum-cascade lasers is applied to kinetics studies of formaldehyde (HCHO) in a shock tube. Multispectral absorption measurements are carried out in a broad spectral range of 1740–1790 cm–1 at temperatures of 800–1500 K and pressures of 2–3 bar. The formation of HCHO from thermal decomposition of 1,3,5-trioxane (C3H6O3, 0.9% diluted in argon) and the subsequent oxidation of formaldehyde is monitored with a time resolution of 4 µs. The rate coefficient of the decomposition of C3H6O3 (i.e., HCHO formation) is found to be k1 = 6.0 × 1015 exp(− 205.58 kJ mol−1/RT) s–1. For the oxidation studies, mixtures of 0.36% C3H6O3 and 1% O2 in argon are used. The information of all laser lines, along with the consideration of individual signal variance of each line, is utilized for kinetic and spectral analysis. The experimental kinetic profiles of HCHO are compared with simulations based on the mechanisms of Zhou et al. (Combust Flame, 197:423–438, 2018) and Cai and Pitsch (Combust Flame, 162:1623–1637, 2015).

中文翻译：

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使用光谱范围为 1740–1790 cm–1 的快速双梳光谱仪监测激波管中的甲醛

基于两个量子级联激光器的双频梳状光谱仪应用于激波管中甲醛 (HCHO) 的动力学研究。多光谱吸收测量在 1740-1790 cm-1 的宽光谱范围内进行，温度为 800-1500 K，压力为 2-3 bar。1,3,5-三恶烷（C3H6O3，在氩气中稀释 0.9%）热分解生成 HCHO 以及随后甲醛的氧化以 4 µs 的时间分辨率进行监测。发现 C3H6O3 分解（即 HCHO 形成）的速率系数为 k1 = 6.0 × 1015 exp(- 205.58 kJ mol-1/RT) s–1。对于氧化研究，使用氩气中 0.36% C3H6O3 和 1% O2 的混合物。所有激光线的信息，以及每条线的单个信号方差的考虑，用于动力学和光谱分析。将 HCHO 的实验动力学曲线与基于 Zhou 等人机制的模拟进行比较。(Combust Flame, 197:423–438, 2018) 和 Cai 和 Pitsch (Combust Flame, 162:1623–1637, 2015)。