SERS of Semiconducting Nanoparticles (TiO2 Hybrid Composites)
SERS of Semiconducting Nanoparticles (TiO2 Hybrid Composites)
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DOI：
10.1021/ja808277u
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发表时间：
2009-05-06
影响因子：
15
通讯作者：
Rajh, Tijana
中科院分区：
文献类型：
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作者：
Musumeci, Anthony;Gosztola, David;Rajh, Tijana
利用拉曼光谱研究了吸附在纳米TiO 2表面的分子的拉曼散射。我们发现强烈的增强拉曼散射的混合复合材料，表现出电荷转移吸收与二氧化钛纳米粒子。在含有TiO 2纳米颗粒和生物分子的溶液中观察到高达10（3）的增强因子，包括重要的神经递质类别，如多巴胺和多巴酚（3，4-二羟基苯乙酸）。只有选定的振动增强，表明分子特异性，由于独特的结合和定向的生物分子耦合到二氧化钛表面。所有的增强模式都与附加分子的不对称振动有关，这些分子使电荷转移复合物的对称性变高。所选振动的强度和能量取决于纳米颗粒载体的尺寸和形状。此外，我们发现，本地化的电荷在量子化的纳米粒子（2 nm），表现为粒子吸收的蓝移，减少Sers增强。重要的是，最小浓度的吸附分子显示出最大的拉曼增强，这表明该系统在检测与金属氧化物纳米颗粒形成电荷转移复合物的生物分子时具有高灵敏度的可能性。混合复合材料的波长依赖特性表明存在拉曼共振态。吸附的分子，不显示电荷转移复合物显示弱增强可能是由于介电腔效应。
Raman scattering of molecules adsorbed on the surface of TiO2 nanoparticles was investigated. We find strong enhancement of Raman scattering in hybrid composites that exhibit charge transfer absorption with TiO2 nanoparticles. An enhancement factor up to similar to 10(3) was observed in the solutions containing TiO2 nanoparticles and biomolecules, including the important class of neurotransmitters such as dopamine and dopac (3,4-dihydroxy-phenylacetic acid). Only selected vibrations are enhanced, indicating molecular specificity due to distinct binding and orientation of the biomolecules coupled to the TiO2 surface. All enhanced modes are associated with the asymmetric vibrations of attached molecules that tower the symmetry of the charge transfer complex. The intensity and the energy of selected vibrations are dependent on the size and shape of nanoparticle support. Moreover, we show that localization of the charge in quantized nanoparticles (2 nm), demonstrated as the blue shift of particle absorption, diminishes SERS enhancement. Importantly, the smallest concentration of adsorbed molecules shows the largest Raman enhancements suggesting the possibility for high sensitivity of this system in the detection of biomolecules that form a charge transfer complex with metal oxide nanoparticles. The wavelength-dependent properties of a hybrid composite suggest a Raman resonant state. Adsorbed molecules that do not show a charge transfer complex show weak enhancements probably due to the dielectric cavity effect.