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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Alkyl Peroxy Radical Kinetics Measured Using Near-infrared CW-Cavity Ring-down Spectroscopy
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Alkyl Peroxy Radical Kinetics Measured Using Near-infrared CW-Cavity Ring-down Spectroscopy

机译：使用近红外连续腔衰荡光谱法测量的烷基过氧自由基动力学

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摘要

A kinetic reactor system is described which couples pulsed laser photolytic production of radicals with continuous laser excitation cavity ring-down spectroscopic detection in the near-infrared (NIR). The atmospherically relevant alkyl peroxy radicals ethyl peroxy (C_2H_5O_2) and methyl peroxy (CH_3O_2) were monitored via their structured absorbance spectra in the NIR near 1.3 μm. These peroxy radicals were then subjected to kinetic study as proof-of-principle for the new technique. Portions of the absorption spectra for the two radicals are reported which agree well with previously published spectra [Hunziker, H. E.: Wendt, H. R. J. Chem. Phys. 1976, 64, 3488. Pushkarsky, M. B.; Zalyubovsky, S. J.; Miller, T. A. J. Chem. Phys. 2000, 112, 10695]. The absorption cross sections were determined at selected wavelengths using the known self-reaction rate coefficients and observed kinetic data. The absorption cross sections determined are as follows: for two of the maxima in the origin band of C_2H_5O_2, σ_(1317.01) nm = σ_(1316.40) nm = (3.0±1.5) * 10~(-21) cm~2 molecule~(-1), and for a maximum in a sequence band of CH_3O_2, σ_(1335.07) nm = (1.5±0.8) * 10~(-20) cm~2 molecule~(-1). Preliminary data for the prototypical peroxy radical cross-reaction between CH_3O_2 and C_2H_5O_2 is presented. This data supports earlier work [Villenave, E.; Lesclaux, R. J. Phys. Chem. 1996, 100, 14372] which established a pressure independent value of k(CH_3O_2 + CH_3CH_2O_2) = 2.0 * 10~(-13) cm~3 molecule~(-1) s~(-1) at 298 K. As in most kinetic studies involving peroxy radicals, the accuracy of the reported rate coefficients is influenced by the details of the complex mechanisms used in the fitting. However, in the current studies, specific radical absorption(s) are used to follow each radicals' decay, which should improve the precision of the determination.
机译：描述了一种动力学反应器系统，该系统将自由基的脉冲激光光解产生与近红外（NIR）中的连续激光激发腔衰荡光谱检测相结合。通过其结构吸光度光谱在近1.3μm的近红外光谱中监测与大气相关的烷基过氧自由基乙基过氧（C_2H_5O_2）和甲基过氧（CH_3O_2）。然后对这些过氧自由基进行动力学研究，以作为新技术的原理证明。报道了两个基团的吸收光谱的部分，它们与先前公开的光谱非常吻合[Hunziker，H.E。：Wendt，H.R.J.Chem.Soc.Chem.Soc。物理1976，64，3488。Pushkarsky，M. B .; Zalyubovsky，S. J .; Miller，T.A. J. Chem。物理2000，112，10695]。使用已知的自反应速率系数和观察到的动力学数据，在选定的波长下确定吸收截面。确定的吸收截面如下：对于C_2H_5O_2的原始带中的两个最大值，σ_（1317.01）nm =σ_（1316.40）nm =（3.0±1.5）* 10〜（-21）cm〜2分子〜 （-1），并且在CH_3O_2的序列带中最大，σ_（1335.07）nm =（1.5±0.8）* 10〜（-20）cm〜2分子〜（-1）。给出了CH_3O_2和C_2H_5O_2之间原型过氧自由基交叉反应的初步数据。该数据支持更早的工作[Villenave，E .; Lesclaux，R.J.Phys。化学[1996，100，14372]建立了在298 K时k（CH_3O_2 + CH_3CH_2O_2）= 2.0 * 10〜（-13）cm〜3分子〜（-1）s〜（-1）的压力无关值。在涉及过氧自由基的动力学研究中，报告的速率系数的准确性受拟合中使用的复杂机制的细节影响。但是，在当前的研究中，特定的自由基吸收用于跟踪每个自由基的衰变，这将提高测定的准确性。

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