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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Experimental and Computational Investigations of the Reaction of OH with CF_3I and the Enthalpy of Formation of HOI
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Experimental and Computational Investigations of the Reaction of OH with CF_3I and the Enthalpy of Formation of HOI

机译：OH与CF_3I反应和HOI生成焓的实验和计算研究

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The kinetics of the reaction of hydroxyl radicals with trifluoroiodomethane were investigated by the flash photolysis-resonance fluorescence technique. A rate constant of k = 5.8 * 10~(-12) exp((-11.3 kJ mol~(-1)/RT) cm~3 molecule~(-1) s~(-1) was measured over the temperature range 280-450 K with accuracy limits of 20% (450 K) to 30% (280 K). Different product channels were investigated by ab initio methods, and the dominant products are CF_3 + HOI. The enthalpy of formation of hypoiodous acid was analyzed with Gaussian-2 theory, in conjunction with G2 energies for INO, ICN, ClCN, and other species. The transition state and reaction coordinate for OH + CF_3I was characterized at the G2(MP2) level, and the results suggest a negligible barrier to the reverse reaction of CF_3 + HOI, so that the measured forward activation energy can be used to derive △_fH_(298)(HOI) = -69.6 ± 5.4 kJ mol~(-1). The implications of the kinetics and thermochemistry for iodine chemistry in flames and the atmosphere are discussed, and for the range 280-2000 K a proposed rate expression is k = 2.9 * 10~(-16)(T/K)~(1.5) exp(-(960 K)/T) cm~3 molecule~(-1) s~(-1).
机译：通过快速光解共振荧光技术研究了羟基自由基与三氟碘甲烷的反应动力学。在整个温度范围内测得的速率常数为k = 5.8 * 10〜（-12）exp（（-11.3 kJ mol〜（-1）/ RT）cm〜3分子〜（-1）s〜（-1） 280-450 K，精度范围为20％（450 K）至30％（280 K），通过从头算方法研究了不同的产物通道，主要产物为CF_3 + HOI，并分析了次碘酸形成的焓根据高斯2理论，结合INO，ICN，ClCN和其他物种的G2能量，OH + CF_3I的跃迁状态和反应坐标在G2（MP2）水平上得到了表征，结果表明对OH + CF_3I的障碍可以忽略不计。 CF_3 + HOI的逆反应，因此测得的正向活化能可用于推导△_fH_（298）（HOI）= -69.6±5.4 kJ mol〜（-1）。动力学和热化学对碘的影响讨论了火焰和大气中的化学反应，对于280-2000 K范围，建议的速率表达式为k = 2.9 * 10〜（-16）（T / K）〜（1.5）exp（-（960 K）/ T ）cm〜3分子〜（-1）s〜（-1）。

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