Transition States and Nonlinear Excitations in Chloroform Observed with a Sub-5 fs Pulse Laser
Transition States and Nonlinear Excitations in Chloroform Observed with a Sub-5 fs Pulse Laser
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DOI：
10.1021/ja801829n
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发表时间：
2009-01-21
影响因子：
15
通讯作者：
Kobayashi, Takayoshi
中科院分区：
文献类型：
--
作者：
Iwakura, Izumi;Yabushita, Atsushi;Kobayashi, Takayoshi
在纯氯仿（CHCl 3）和氧饱和氯仿（O-2-CHCl 3）中CHCl 3中心点中心点O-2电荷转移复合物中观察到的Sub-5 fs脉冲动力学分别由激发态和基态的波包运动主导。CHCl 3的时间分辨信号表现出由三光子吸收过程产生的电子激发态的动力学，O-2-CHCl 3的时间分辨信号用受激拉曼过程激发的电子基态的动力学来解释。此外，我们还发现在可见光脉冲照射下，氯仿与氧的电荷转移复合物中的氯仿氧化反应很容易通过受激拉曼过程触发的C-H插入过程进行。光谱图分析使得能够直接观察拉曼触发氧化过程的实时动力学。这些结果表明，观察过渡态的子5 fs的时间分辨光谱是适用于“基态反应”，以及“激发态反应”通过受激拉曼激发在各种各样的化学反应。
Sub-5 fs pulse dynamics observed in neat chloroform (CHCl3) and the CHCl3 center dot center dot center dot O-2 charge-transfer complex in oxygen-saturated chloroform (O-2-CHCl3) were found to be dominated by wave packet motions in the excited state and the ground state, respectively. The time-resolved signal of CHCl3 exhibits dynamics in the electronic excited state generated by a three-photon absorption process, and that Of O-2-CHCl3 is explained in terms of the dynamics of the electronic ground state excited by the stimulated Raman process. In addition, we found that the oxidation reaction of chloroform in the charge-transfer complex of chloroform and oxygen easily proceeds via a C-H insertion process triggered by the stimulated Raman process under the irradiation of a visible laser pulse. The spectrogram analysis enabled direct observation of the real-time dynamics of the Raman-triggered oxidation process. These results demonstrate that observation of transition states by sub-5 fs time-resolved spectroscopy is applicable to "ground-state reactions" as well as "excited-state reactions" via stimulated Raman excitation in a wide variety of chemical reactions.