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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Absolute Rate Coefficient of the Gas-Phase Reaction between Hydroxyl Radical (OH) and Hydroxyacetone: Investigating the Effects of Temperature and Pressure
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Absolute Rate Coefficient of the Gas-Phase Reaction between Hydroxyl Radical (OH) and Hydroxyacetone: Investigating the Effects of Temperature and Pressure

机译：羟基自由基（OH）与羟基丙酮之间气相反应的绝对速率系数：研究温度和压力的影响

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The rate coefficient (k1) of the reaction between hydroxyl radical and hydroxyacetone, which remained so far controversial, was determined over the temperature range 290?500 K using pulsed-laser photolysis coupled to pulsed-laser induced fluorescence (PLP-PLIF). Hydroxyl radical was generated by pulsed photolysis of H_2O_2 at 248 nm. The results show that at a pressure of 50 Torr He, the rate coefficient obeys a negative temperature dependence k_1(T) = (1.77 ± 0.19) × 10~(?12) exp((353 ± 36)/T) cm~3 molecule~(?1) s~(?1) for temperatures between 290 and 380 K, in good agreement with the results of Dillon et al. (Phys. Chem. Chem. Phys. 2006, 8, 236) at 60 Torr He. However, always at 50 Torr He but for the higher temperature range 410?500 K, a positive temperature dependence was found: k_1(T) = (1.14 ± 0.25) × 10~(?11) exp(?(378 ± 102)/T) cm~3 molecule~(?1) s~(?1), close to the expression obtained by Baasandorj et al. (J. Phys. Chem. A 2009, 113, 10495) for pressures of 2 and 5 Torr He but at lower temperatures, 280?360 K, where their k_1(T) values are well below these of Dillon et al. and of this work. Moreover, the rate coefficient k1(301 K) determined as a function of pressure, from 10 to 70 Torr He, shows a pronounced decrease once the pressure is below ～40 Torr He, thus explaining the disparity between the higher-pressure data of Dillon et al. and the lower-pressure results of Baasandorj et al. The pressure dependence of k1 and of its temperature-dependence below ～400 K is rationalized by the reaction proceeding via a hydrogen-bonded prereactive complex (PRC) and a submerged transition state, such that at high pressures collisionally thermalized PRCs contribute additional reactive flux over and through the submerged barrier. The high-pressure rate coefficient data both of Dillon et al. and of this work over the combined range 230?500 K can be represented by the theory-based expression k_1(T) = 5.3 × 10~(?20) × T~(2.6) exp(1100/T) cm~3 molecule~(?1) s~(?1).
机译：使用脉冲激光光解与脉冲激光诱导的荧光（PLP-PLIF）耦合，在290-500 K的温度范围内确定了至今仍存在争议的羟基自由基与羟基丙酮之间的反应速率系数（k1）。通过在248 nm处对H_2O_2进行脉冲光解产生了羟基自由基。结果表明，在50 Torr He的压力下，速率系数符合负温度依赖性k_1（T）=（1.77±0.19）×10〜（？12）exp（（353±36）/ T）cm〜3在290至380 K之间的温度下，分子（？1）s〜（？1）与Dillon等人的结果非常吻合。 （Phys.Chem.Chem.Phys.2006，8，236）在60 Torr He。但是，始终在50 Torr He下，但对于较高的温度范围410？500 K，发现正温度依赖性：k_1（T）=（1.14±0.25）×10〜（？11）exp（？（378±102） / T）cm〜3分子〜（？1）s〜（？1），接近Baasandorj等人获得的表达。 （J. Phys。Chem。A 2009，113，10495）在2和5 Torr He的压力下，但在较低的温度280？360 K下，其k_1（T）值远低于Dillon等人的值。和这项工作。此外，一旦压力低于〜40 Torr He，根据压力确定的比率系数k1（301 K）会显着下降，从而解释了Dillon高压数据之间的差异。等。 Baasandorj等人的低压结果。 k1的压力依赖性及其低于〜400 K的温度依赖性可通过氢键预反应复合物（PRC）和浸没的过渡态进行反应来合理化，从而在高压下，碰撞热的PRCs贡献了额外的反应通量。并通过淹没的屏障。 Dillon等人的高压速率系数数据。这项工作在230至500 K的组合范围内可以用基于理论的表达式k_1（T）= 5.3×10〜（？20）×T〜（2.6）exp（1100 / T）cm〜3分子表示〜（？1）s〜（？1）。

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