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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Recombination, Solvation and Reaction of CN Radicals Following Ultraviolet Photolysis of ICN in Organic Solvents
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Recombination, Solvation and Reaction of CN Radicals Following Ultraviolet Photolysis of ICN in Organic Solvents

机译：有机溶剂中ICN的紫外线光解后CN自由基的重组，溶剂化和反应

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The fates of CN radicals produced by ultraviolet (UV) photolysis of ICN in various organic solvents have been examined by transient electronic and vibrational absorption spectroscopy (TEAS and TVAS). Near-UV and visible bands in the TEAS measurement enable direct observation of the CN radicals and their complexes with the solvent molecules. Complementary TVAS measurements probe the products of CN-radical reactions. Geminate recombination to form ICN and INC is a minor pathway on the ISO fs -1300 ps time scales of our experiments in the chosen organic solvents; nonetheless, large infrared transition dipole moments permit direct observation of INC that is vibrationally excited in the C N stretching mode. The time constants for INC vibrational cooling range from 30 ps in tetrahydrofuran (THF) to 1400 ps in more weakly interacting solvents such as chloroform. The major channel for CN removal in the organic solvents is reaction with solvent molecules, as revealed by depletion of solvent absorption bands and growth of product bands in the TVA spectra. HCN is a reaction product of hydrogen atom abstraction in most of the photoexcited solutions, and forms with vibrational excitation in both the C-H and C N stretching modes. The vibrational cooling rate of the C N stretch in HCN depends on the solvent, and follows the same trend as the cooling rate of the C N stretch in INC. However, in acetonitrile solution an additional reaction pathway produces C3H3N2 center dot radicals, which release HCN on a much longer time scale.
机译：已经通过瞬态电子和振动吸收光谱法（TEAS和TVAS）检查了在各种有机溶剂中ICN的紫外线（UV）光解产生的CN自由基的命运。 TEAS测量中的近紫外带和可见带使得可以直接观察CN自由基及其与溶剂分子的配合物。补充TVAS测量可探测CN自由基反应的产物。在我们选择的有机溶剂中，在我们的实验的ISO fs -1300 ps时间尺度上，双歧杆菌重组形成ICN和INC是一条次要途径;但是，大的红外跃迁偶极矩可直接观察在C N拉伸模式下振动激发的INC。 INC振动冷却的时间常数范围从四氢呋喃（THF）中的30 ps到相互作用较弱的溶剂（如氯仿）中的1400 ps。有机溶剂中CN去除的主要途径是与溶剂分子反应，这通过TVA光谱中溶剂吸收带的耗尽和产物带的增长来揭示。 HCN是大多数光激发溶液中氢原子抽象的反应产物，并在C-H和C N拉伸模式下均通过振动激发形成。 HCN中CN链段的振动冷却速率取决于溶剂，并遵循与INC中CN链段的冷却速率相同的趋势。但是，在乙腈溶液中，另外的反应途径会产生C3H3N2中心点自由基，从而在HCN上释放HCN。更长的时间范围。

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