The rate constant and branching ratios of ethyl reaction with hydroperoxyl radical, C₂H₅ + HO₂ (1), a key radical-radical reaction for intermediate temperature combustion chemistry, were measured in situ for the first time in a photolysis Herriott cell by using mid-IR Faraday rotation spectroscopy (FRS) and UV-IR direct absorption spectroscopy (DAS). The microsecond time-resolved diagnostic technique in this work enabled the direct rate measurements of the target reaction at 40 and 80 mbar and reduced the experimental uncertainty considerably. C₂H₅ and HO₂ radicals were generated by the photolysis of (COCl)₂/C₂H₅I/CH₃OH/O₂/He mixture at 266 nm. By direct measurements of the transient profiles of C₂H₅, HO₂ and OH concentrations, the overall rate constant for this reaction at 297 K was determined as k₁(40 mbar) = (3.8 ± 0.8) × 10${}^{-11}$ cm³ molecule${}^{-1}$ s${}^{-1}$ and k₁(80 mbar) = (4.1 ± 1.0) × 10${}^{-11}$ cm³ molecule${}^{-1}$ s${}^{-1}$. The direct observation of hydroxyl radical (OH) indicated that OH formation channel was the major channel with a branching ratio of 0.8 ± 0.1.

首次在光解Herriott电池中原位测量了与氢过氧自由基C ₂ H ₅ + HO ₂（1）的乙基反应的速率常数和支化比，C ₂ H ₅ + HO ₂是中温燃烧化学的关键自由基自由基反应。使用中红外法拉第旋转光谱（FRS）和紫外红外直接吸收光谱（DAS）。这项工作中的微秒时间分辨诊断技术可以在40和80 mbar下对目标反应进行直接速率测量，并大大降低了实验不确定性。（COCl）₂ / C ₂的光解产生C ₂ H ₅和HO ₂自由基在266 nm下的H ₅ I / CH ₃ OH / O ₂ / He混合物。通过直接测量C ₂ H ₅，HO ₂和OH浓度的瞬态曲线，可以确定该反应在297 K时的总速率常数为k ₁（40 mbar）=（3.8±0.8）×10${}^{-11}$cm ³分子${}^{-\mathrm{1个}}$ s${}^{-\mathrm{1个}}$和k ₁（80 mbar）=（4.1±1.0）×10${}^{-11}$cm ³分子${}^{-\mathrm{1个}}$ s${}^{-\mathrm{1个}}$。羟基自由基（OH）的直接观察表明，OH形成通道是主要通道，支化比为0.8±0.1。