Photoionization-induced water migration in the hydrated trans-formanilide cluster cation revealed by gas-phase spectroscopy and ab initio molecular dynamics simulation
Photoionization-induced water migration in the hydrated trans-formanilide cluster cation revealed by gas-phase spectroscopy and ab initio molecular dynamics simulation
复制标题
气相光谱和从头算分子动力学模拟揭示了水合反式苯胺簇阳离子中光电离诱导的水迁移
DOI：
10.1021/jp301804w
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发表时间：
2012
期刊：
影响因子：
2.9
通讯作者：
Hiroshi Sekiya
中科院分区：
文献类型：
--
作者：
Takamasa Ikeda;Kenji Sakota;Yukio Kawashima;Hiroshi Sekiya
用红外光谱、量子化学计算和从头算分子动力学模拟研究了反式甲酰苯胺-水1：1团簇FA-（H_2O）_1中光电离诱导的水迁移.在SO状态下，FA-（H2O）1有两种结构异构体，FA（NH）-（H2O）1和FA（CO）-（H2O）1，其中水分子分别与NH基团和CO基团氢键结合。此外，在[FA-（H2O）1]+质量通道中观察到FA（CO）-（H2O）2的S1-S 0起源跃迁，其中水二聚体与CO基团氢键结合，表明其中一个水分子在D 0状态下完全蒸发。这些结果与先前的报告[Robertson，E. G.Chem. Phys. Lett.，2000，325，299]。而在D 0态，由FA（NH）-（H2O）1和FA（CO）-（H2O）1的S1-S 0跃迁光电离产生的[FA-（H2O）1]+的红外光谱基本相同。与理论计算值比较，[FA-（H2O）1]+可归属为[FA（NH）-（H2O）1]+。这意味着当[FA-（H2O）1]+通过FA（CO）-（H2O）1的光电离产生时，[FA-（H2O）1]+中的水分子从CO基团迁移到NH基团。FA（CO）-（H_2O）_2光电离产生的[FA-（H_2O）_1]~+也显示出与[FA（NH）-（H_2O）_1]~+相对应的红外光谱。在这种情况下，随着水分子的蒸发，水从CO基团迁移到NH基团。从头算分子动力学模拟揭示了水在[FA-（H2O）1]+中的迁移途径。经典静电相互作用的计算表明，FA+与H2O之间的电荷-偶极相互作用引起[FA-（H2O）1]+的初始结构变化。[FA-（H2O）1]+中CO基团和H2O的孤对电子之间的交换排斥也影响水迁移的初始方向。这两个因素在确定初始水迁移路径中起着重要作用。
Photoionization-induced water migration in thetrans-formanilide–water 1:1 cluster, FA-(H2O)1, has been investigated by using IR-dip spectroscopy, quantum chemical calculations, and ab initio molecular dynamics simulations. In the S0state, FA-(H2O)1has two structural isomers, FA(NH)-(H2O)1and FA(CO)-(H2O)1, where a water molecule is hydrogen-bonded (H-bonded) to the NH group and the CO group, respectively. In addition, the S1–S0origin transition of FA(CO)-(H2O)2, where a water dimer is H-bonded to the CO group, was observed only in the [FA-(H2O)1]+mass channel, indicating that one of the water molecules evaporates completely in the D0state. These results are consistent with a previous report [Robertson, E. G.Chem. Phys. Lett.,2000,325, 299]. In the D0state, however, [FA-(H2O)1]+produced by photoionization via the S1–S0origin transitions of FA(NH)-(H2O)1and FA(CO)-(H2O)1shows essentially the same IR spectra. Compared with the theoretical calculations, [FA-(H2O)1]+can be assigned to [FA(NH)-(H2O)1]+. This means that the water molecule in [FA-(H2O)1]+migrates from the CO group to the NH group when [FA-(H2O)1]+is produced by photoionization of FA(CO)-(H2O)1. [FA-(H2O)1]+produced by photoionization of FA(CO)-(H2O)2also shows the IR spectrum corresponding to [FA(NH)-(H2O)1]+. In this case, the water migration from the CO group to the NH group occurs with the evaporation of a water molecule. Ab initio molecular dynamics simulations revealed the water migration pathway in [FA-(H2O)1]+. The calculations of classical electrostatic interactions show that charge-dipole interaction between FA+and H2O induces an initial structural change in [FA-(H2O)1]+. An exchange repulsion between the lone pairs of the CO group and H2O in [FA-(H2O)1]+also affects the initial direction of the water migration. These two factors play important roles in determining the initial water migration pathway.