Ultrafast Optical Processes Laboratory, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Phys Chem B. 2013 Apr 25;117(16):4354-64. doi: 10.1021/jp3069333. Epub 2012 Sep 25.
The degenerate transition corresponding to asymmetric stretches of the D(3h) tricyanomethanide anion, C(CN)(3)(-), in aqueous solution was investigated by linear FTIR spectroscopy, femtosecond pump–probe spectroscopy, and 2D IR spectroscopy. Time resolved vibrational spectroscopy shows that water induces vibrational energy transfer between the degenerate asymmetric stretch modes of tricyanomethanide. The frequency–frequency correlation function and the vibrational energy transfer show two significantly different ultrafast time scales. The system is modeled with molecular dynamics simulations and ab initio calculations. A new model for theoretically describing the vibrational dynamics of a degenerate transition is presented. Microscopic models, where water interacts axially and radially with the ion, are suggested for the transition dipole reorientation mechanism.
通过线性傅里叶变换红外光谱、飞秒泵浦-探测光谱和二维红外光谱研究了水溶液中 D(3h) 三氰甲烷阴离子，C(CN)(3)(-) 的简并跃迁。时间分辨振动光谱表明，水诱导三氰甲烷阴离子简并不对称伸缩模式之间的振动能量转移。频率-频率相关函数和振动能量转移显示出两个明显不同的超快时间尺度。该体系通过分子动力学模拟和从头算计算进行建模。提出了一种新的理论模型来描述简并跃迁的振动动力学。对于跃迁偶极子重取向机制，提出了轴向和径向与离子相互作用的微观模型。
