Resonance Raman scattering of rhodamine 6G as calculated using time-dependent density functional theory
Resonance Raman scattering of rhodamine 6G as calculated using time-dependent density functional theory
复制标题
DOI：
10.1021/jp0610867
复制
发表时间：
2006-05-11
影响因子：
2.9
通讯作者：
Schatz, GC
中科院分区：
文献类型：
--
作者：
Jensen, L;Schatz, GC
在这项工作中，我们首次计算了罗丹明 6G (R6G) 的共振拉曼散射 (RRS) 光谱，罗丹明 6G 是表面增强拉曼散射 (SERS) 中的原型分子。该计算是使用最近开发的时间相关密度泛函理论（TDDFT）方法完成的，该方法使用短时近似来评估拉曼散射截面。该方法计算得到的正常拉曼光谱与实验结果吻合较好。计算的 RRS 光谱与 S-1 态激发对应的波长处的 SERS 结果定性一致，但与 S-1 电子振动边带激发对应的波长处测量的 RRS 光谱存在显着差异。尽管与实验的一致性并不完美，但结果提供了对 R6G 在接近吸收最大值的波长处的 RRS 光谱的深入了解，在该波长处，实验由于强荧光而受到阻碍。计算得出的共振增强量约为 10(5)。这表明SERS需要约10(10)的表面增强因子才能实现R6G的单分子检测。
In this work, we present the first calculation of the resonance Raman scattering (RRS) spectrum of rhodamine 6G (R6G) which is a prototype molecule in surface-enhanced Raman scattering (SERS). The calculation is done using a recently developed time-dependent density functional theory (TDDFT) method, which uses a short-time approximation to evaluate the Raman scattering cross section. The normal Raman spectrum calculated with this method is in good agreement with experimental results. The calculated RRS spectrum shows qualitative agreement with SERS results at a wavelength that corresponds to excitation of the S-1 state, but there are significant differences with the measured RRS spectrum at wavelengths that correspond to excitation of the vibronic sideband of S-1. Although the agreement with the experiments is not perfect, the results provide insight into the RRS spectrum of R6G at wavelengths close to the absorption maximum where experiments are hindered due to strong fluorescence. The calculated resonance enhancements are found to be on the order of 10(5). This indicates that a surface enhancement factor of about 10(10) would be required in SERS in order to achieve single-molecule detection of R6G.