Excited State Intramolecular Proton Transfer of 1-Hydroxyanthraquinone
Excited State Intramolecular Proton Transfer of 1-Hydroxyanthraquinone
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DOI：
10.1063/1674-0068/28/cjcp1504078
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发表时间：
2015-10
影响因子：
1
通讯作者：
Si-mei Sun;Song Zhang;Kai Liu;Ya-ping Wang;Miaomiao Zhou;Bing Zhang
中科院分区：
文献类型：
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作者：
Si-mei Sun;Song Zhang;Kai Liu;Ya-ping Wang;Miaomiao Zhou;Bing Zhang
通过飞秒瞬态吸收光谱和量子化学计算研究了溶液中1-羟基蒽醌的激发态分子内质子转移动力学。在400 nm泵浦波长的激发下，瞬态吸收光谱观察到激发态吸收和受激发射两个特征谱带。根据延迟的受激发射信号，确定分子内质子转移的时间尺度约为 32 fs。量子化学计算表明，分子轨道以及S-2和S-1态的顺序是相反的，并且沿着质子转移坐标存在圆锥形交叉点。质子转移后，通过圆锥形交叉点填充的互变异构体的第二激发态经历类似于 200 fs 的内部转换，并随后经历类似于 16 ps 的分子间能量弛豫。较长的分量 300 ps 可以用从激发态互变异构体到基态的弛豫来解释。根据我们的观察，提出了两条通过圆锥形交叉点的质子转移路径，其中占主导地位的一条保留了分子轨道。
The excited state intra-molecular proton transfer dynamics of 1-hydroxyanthraquinone in solution are investigated by femtosecond transient absorption spectroscopy and quantum chemistry calculations. Two characteristic bands of excited state absorption and stimulated emission are observed in transient absorption spectra with the excitation by the pump wavelength of 400 nm. From the delayed stimulated emission signal, the time scale of the intra-molecular proton transfer is determined to be about 32 fs. The quantum chemistry calculations show that the molecular orbits and the order of the S-2 and S-1 states are reversal and a conical intersection is demonstrated to exist along the proton transfer coordinate. After proton transfer, the second excited state of tautomer populated via the conical intersection undergoes the internal conversion with similar to 200 fs and the following intermolecular energy relaxation with similar to 16 ps. The longer component 300 ps can be explained in terms of the relaxation from excited-state tautomer to its ground state. From our observations, two proton transfer pathways via a conical intersection are proposed and the dominated one preserves the molecular orbits.