拉曼响应中的化学键效应：苯乙炔吸附在银原子簇上
On the chemical bonding effects in the Raman response: Benzenethiol adsorbed on silver clusters
摘要：
利用含时密度泛函理论（TDDFT）研究了化学键对苯乙烷在银原子团簇上化学吸附的拉曼散射的影响。拉曼散射截面计算使用的形式主义，采用分析衍生物的频率依赖性的电子极化率，它对待两个非共振和共振增强在同一计划。在非共振区，拉曼散射到分子振动模式增强了一个数量级，并显示出明显的依赖于分子的取向和局部对称性。额外的强烈增强的顺序$10^2$产生的共振跃迁到混合金属-分子电子状态。拉曼增强分析使用的范围内的激发能$1.6-3.0$ eV，其中孤立的苯乙撑没有电子跃迁的拉曼激发配置文件（REPs）。计算得到的金属-分子复合物的振动频移和相对拉曼散射截面与苯乙炔吸附在银表面的表面增强拉曼散射（SERS）实验数据吻合得很好。这些效应的表征和理解，与化学增强机制，可以用来提高分子拉曼散射的检测灵敏度。
英文摘要：
We study the effects of chemical bonding on Raman scattering from benzenethiol chemisorbed on silver clusters using time-dependent density functional theory (TDDFT). Raman scattering cross sections are computed using a formalism that employs analytical derivatives of frequency-dependent electronic polarizabilities, which treats both off-resonant and resonant enhancement within the same scheme. In the off-resonant regime, Raman scattering into molecular vibrational modes is enhanced by one order of magnitude and shows pronounced dependence on the orientation and the local symmetry of the molecule. Additional strong enhancement of the order of $10^2$ arises from resonant transitions to mixed metal--molecular electronic states. The Raman enhancement is analyzed using Raman excitation profiles (REPs) for the range of excitation energies $1.6-3.0$ eV, in which isolated benzenethiol does not have electronic transitions. The computed vibrational frequency shifts and relative Raman scattering cross sections of the metal--molecular complexes are in good agreement with experimental data on surface enhanced Raman scattering (SERS) for benzenethiol adsorbed on silver surfaces. Characterization and understanding of these effects, associated with chemical enhancement mechanism, may be used to improve the detection sensitivity in molecular Raman scattering.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
