An electric field is created upon photoinduced charge separation in electron donor–acceptor (D–A) molecules. The photophysics of a prototypical D–A molecule, 4-(dimethylamino)-benzonitrile (DMABN), has been under extensive investigation for decades. Here, by using the framework of the vibrational Stark effect (VSE), we show that the nitrile vibration quantifies a significant induced electric field in the intramolecular charge-transfer state of DMABN. We further demonstrate that such a phenomenon can be observed in a structurally similar aryl nitrile and that the VSE depends on solvent polarity due to dielectric screening. Our current work shows how the superb sensitivity of the nitrile vibration can be used to identify the nature of electron delocalization and quantify the induced electric field in photoinduced charge transfer processes.

中文翻译：

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腈振动报告在芳基腈的电荷转移状态下感应电场和电子离域

在电子供体-受体（D-A）分子中光诱导的电荷分离后会产生一个电场。原型D–A分子4-（二甲基氨基）-苯甲腈（DMABN）的光物理性质已经进行了数十年的广泛研究。在这里，通过使用振动斯塔克效应（VSE）的框架，我们表明腈振动可以量化DMABN分子内电荷转移状态下的显着感应电场。我们进一步证明，在结构相似的芳基腈中可以观察到这种现象，并且由于介电筛选，VSE取决于溶剂极性。我们目前的工作表明，腈振动的超高灵敏度可用于识别电子离域的性质并量化光感应电荷转移过程中的感应电场。