No Straight Path: Roaming in Both Ground- and Excited-State Photolytic Channels of NO3→NO+O2
No Straight Path: Roaming in Both Ground- and Excited-State Photolytic Channels of NO3→NO+O2
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DOI：
10.1126/science.1216911
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发表时间：
2012-03-02
期刊：
影响因子：
56.9
通讯作者：
North, Simon W.
中科院分区：
文献类型：
--
作者：
Grubb, Michael P.;Warter, Michelle L.;North, Simon W.
最近在几个化学反应中观察到漫游机制，以及通过传统过渡态的轨迹。在这里，我们证明了可见光诱导的反应NO3 -> NO + O-2的进行完全漫游。高水平从头计算预测特定的NO λ双峰倾向（相对于分子旋转平面的未成对电子的取向），我们辨别实验离子成像的这种机制。这些数据提供了两种不同电子状态下漫游路径的直接证据，对应于先前记录的产生NO + O-2的光解通道。更广泛地说，这些结果对这种不寻常的反应机制的总体流行提出了有趣的问题。
Roaming mechanisms have recently been observed in several chemical reactions alongside trajectories that pass through a traditional transition state. Here, we demonstrate that the visible light-induced reaction NO3 -> NO + O-2 proceeds exclusively by roaming. High-level ab initio calculations predict specific NO Lambda doublet propensities (orientations of the unpaired electron with respect to the molecular rotation plane) for this mechanism, which we discern experimentally by ion imaging. The data provide direct evidence for roaming pathways in two different electronic states, corresponding to both previously documented photolysis channels that produce NO + O-2. More broadly, the results raise intriguing questions about the overall prevalence of this unusual reaction mechanism.