The first laser induced fluorescence (LIF) spectrum for the tert-butoxy radical is reported following radical generation by excimer laser photolysis of tert-butyl nitrite. The laser flash photolysis-LIF technique is used to measure the temperature dependence of the rate coefficient for the reaction with NO (T=200–390 K): which can be represented in either Arrhenius or AT-n format: and the tert-butoxy decomposition. Whilst the former reaction shows no pressure dependence (p=70–500 Torr of helium), the latter reaction is in the fall-off regime over the entire range of experimental conditions (T=303–393 K, p=13–600 Torr helium). The fall-off data were fitted using an inverse Laplace transformation/master equation model to give the following Arrhenius parameters: These Arrhenius parameters are significantly lower than previous indirect measurements or calculations and the atmospheric and mechanistic implications are discussed.Finally, reaction (3) was also studied by monitoring the temporal dependence of the NO LIF signal following the photolysis of tert-butylnitrite with no additional NO. The results are in good agreement with the tert-butoxy monitoring and allow for an estimation of the rate parameters for the tert-butoxy self reaction.
首次报道了叔丁氧自由基的激光诱导荧光(LIF)光谱,该自由基是通过
氙气激光光解叔丁基
亚硝酸酯产生的。利用激光闪光光解-LIF技术测量了与NO反应的速率系数的温度依赖性(T=200–390 K),反应速率可以用Arrhenius或AT-n格式表示,以及叔丁氧的分解。前者反应没有压力依赖性(p=70–500托
氦气),后者反应在整个实验条件范围内处于衰减区(T=303–393 K, p=13–600托
氦气)。衰减数据通过逆拉普拉斯变换/主方程模型拟合,得到了以下Arrhenius参数: 这些Arrhenius参数显著低于先前的间接测量或计算值,并讨论了它们在大气和机理方面的含义。最后,通过监测NO LIF信号的时间依赖性,在没有额外NO的情况下,对叔丁基
亚硝酸酯的光解反应(3)进行了研究。结果与叔丁氧监测结果一致,并使得对叔丁氧自身反应的速率参数进行估计成为可能。