NH is a key short-lived radical involved in the prompt-NO formation. Quantification of NH is thus particularly important for testing the NO kinetic mechanisms. However, quantitative measurements of native NH in hydrocarbon/oxygen/nitrogen flames remain very scarce. Therefore, in this work, the mole fractions of native NH were obtained using a combination of laser-based diagnostics; Laser Induced Fluorescence (LIF) and Cavity Ring-Down Spectroscopy (CRDS). The NH species was probed after exciting the transition R₁(6) in the A³Π-X³Σ⁻ (0-0) system at 333.9 nm. The mole fraction profiles of NH were successfully obtained in premixed low-pressure flames of CH₄/O₂/N₂ and C₂H₂/O₂/N₂ at two equivalence ratios of 1.00 and 1.25. The estimated detection limit for the NH radical was around 4.5 × 10⁸ molecule cm⁻³ (i.e. 2 ppb in mole fraction at 1600 K), which is nearly 2 orders of magnitude lower than previous values reported in the literature. These new experimental results were compared with predictions by a recently developed NO model (namely NOMecha2.0). In the case of the CH₄ flames, a satisfying agreement between the experiment and model was observed. However, in the case of the C₂H₂ flames, some discrepancies were observed. Model analysis has highlighted the importance of the HCCO radicals in the NH formation through the HCNO→HNCO→NH₂ reactions pathway. Modification of the rate constant values of the reactions C₂H₂+ O and HCCO + O₂, which are key reactions for both the acetylene laminar flame speed and the HCCO predictions, has enabled the model to satisfactorily predict the experimental NH and NO profiles also in the C₂H₂ flames.

NH是参与NO迅速形成的关键短命自由基。因此，NH的定量对于测试NO动力学机理尤为重要。然而，烃/氧/氮火焰中天然NH的定量测量仍然非常稀少。因此，在这项工作中，天然NH的摩尔分数是结合使用基于激光的诊断方法获得的。激光诱导荧光（LIF）和腔衰荡光谱（CRDS）。的NH物种激发过渡后R探测₁在A（6）³ Π-X ³ Σ ^-在333.9纳米（0-0）系统。在CH ₄ / O ₂ / N _2的预混合低压火焰中成功获得了NH的摩尔分数分布和C ₂ H ₂ / O ₂ / N ₂的两个当量比为1.00和1.25。NH自由基的估计检出限约为4.5×10 ⁸分子cm ^-3（即，在1600 K下摩尔分数为2 ppb），比文献中报道的先前值低了近2个数量级。将这些新的实验结果与最近开发的NO模型（即NOMecha2.0）的预测结果进行了比较。在CH ₄火焰的情况下，观察到实验与模型之间的令人满意的一致性。但是，在C ₂ H ₂的情况下火焰，观察到一些差异。模型分析突出了HCCO自由基通过HCNO→HNCO→NH ₂反应途径在NH形成中的重要性。反应C ₂ H ₂的速率常数值的修改+ O和HCCO + O ₂是乙炔层流火焰速度和HCCO预测的关键反应，已使模型能够令人满意地预测C ₂ H ₂火焰中的实验NH和NO分布。