Mani Tomoyasu, Grills David C
Department of Chemistry , University of Connecticut , Storrs , Connecticut 06269-3060 , United States.
Chemistry Division , Brookhaven National Laboratory , Upton , New York 11973-5000 , United States.
J Phys Chem A. 2018 Sep 20;122(37):7293-7300. doi: 10.1021/acs.jpca.8b08025. Epub 2018 Sep 7.
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.
在电子供体-受体（D-A）分子中，光致电荷分离时会产生电场。几十年来，典型的D-A分子4-（二甲基氨基）苯甲腈（DMABN）的光物理性质一直受到广泛研究。在此，通过使用振动斯塔克效应（VSE）框架，我们表明腈振动量化了DMABN分子内电荷转移态中的显著感应电场。我们进一步证明，这种现象可以在结构相似的芳基腈中观察到，并且由于介电屏蔽，VSE取决于溶剂极性。我们目前的工作展示了腈振动的超高灵敏度如何用于识别电子离域的性质，并量化光致电荷转移过程中的感应电场。
