The adsorption of 3,4,9,10-perylene tetracarboxylic acid (PTCA) on Ag and Au self-assembled films has been investigated through surface-enhanced Raman scattering (SERS). The spectrum of PTCA reveals a strong excitation wavelength dependence. On the basis of Herzberg–Teller selection rules, it is deduced that appearance of a new b₁ mode of PTCA is selectively enhanced by charge-transfer resonance. Moreover, density functional theory (DFT) calculations were also performed to identify the expected vibrational modes and electronic transitions. The information obtained from the adsorption of PTCA on Ag/Au by SERS is helpful to understand the Herzberg–Teller selection rule. Meanwhile, it provides evidence to explain Raman vibronic modes observed when charge-transfer resonances appear in metal–dye systems.

中文翻译：

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Ag / PTCA中表面增强拉曼光谱的电荷转移效应：Herzberg–Teller选择规则

通过表面增强拉曼散射（SERS）研究了3,4,9,10-per四甲酸（PTCA）在Ag和Au自组装膜上的吸附。PTCA的光谱显示出强烈的激发波长依赖性。根据Herzberg-Teller选择规则，可以推断出PTCA的新b ₁模式的出现是通过电荷转移共振选择性地增强的。此外，还执行了密度泛函理论（DFT）计算，以识别预期的振动模式和电子跃迁。SERS从PTCA在Ag / Au上的吸附获得的信息有助于理解Herzberg–Teller选择规则。同时，它提供了证据来解释当电荷转移共振出现在金属-染料系统中时观察到的拉曼振动模式。