Surface enhance Raman scattering in aligned metal/semiconductor nanocrystals

我们通过测量拉曼散射和光致发光光谱研究了半导体纳米晶和金属纳米晶之间的电子相互作用。首先，我们讨论了半导体纳米晶的拉曼散射光谱形状。利用考虑动量守恒定律松弛的声子限制模型计算了拉曼散射谱形。我们使用的半导体纳米晶有可能形成闪锌矿或纤锌矿的晶体结构。假定纤锌矿结构的拉曼散射光谱更好地解释了实验光谱。这一结果与由透射电子显微镜获得的晶体结构相一致。接下来，我们制备了紧密堆积的半导体/金属混合纳米颗粒单分子膜，并同时测量了…的拉曼散射光谱和光致发光光谱。进一步研究了半导体纳米粒子的拉曼散射和光致发光特性对金属纳米粒子表面等离子体的影响。透射电子显微镜图像显示，成功制备了紧密堆积的半导体/金属纳米颗粒单分子膜。随着金属纳米粒子比例的增加，发光强度急剧下降，而拉曼散射强度略有增加。时间分辨光致发光光谱表明，半导体纳米晶中的光激发激子能量向金属纳米粒子转移。观察到的半导体纳米粒子数密度对拉曼散射和光致发光强度的依赖关系可以用一个考虑电磁增强和能量转移效应的能量转移模型来解释。我们证明了同时测量拉曼散射和光致发光光谱是了解金属和半导体纳米结构之间相互作用的有用技术。较少

We studied electronic interaction between semiconductor nanocrystals and metal nanocrystals by measuring Raman scattering and photoluminescence spectra. First, we discussed Raman scattering spectral shape of semiconductor nanocrystals. The Raman scattering spectral shape was calculated by a phonon confinement model considering the relaxation of the momentum conservation rule. The semiconductor nanocrystals we used had a possibility to farm zincblende or wurtzite crystal structure. The calculated Raman scattering spectra assuming wurtzite structure were more preferable to explain the experimental spectra. This result was consistent with the crystal structure obtained from TEM images. Our finding indicates that we can determine the nanocrystal structure from the Raman scattering analyses without using e. g. TEM.Next, we fabricated close-packed semiconductor/metal mixed nanoparticle monolayers and measured the Raman scattering and photoluminescence spectra simultaneously, in order to inve … More stigate the influence of the Raman scattering and photoluminescence properties of semiconductor nanoparticles on the surface plasmons of metal nanoparticles. The TEM images showed that close-packed semiconductor/metal nanoparticle monolayers were successfully fabricated. With an increase of the metal nanoparticle ratio, the PL intensity decreased dramatically, while the Raman scattering intensity increased slightly. The time-resolved photoluminescence spectra showed that the photo-excited exciton energy in semiconductor nanocrystals transferred to metal nanoparticles. The observed semiconductor-nanoparticle number density dependences of the Raman scattering and photoluminescence intensities were able to be explained by an energy transfer model which considered the effects of electromagnetic enhancement and energy transfer. We demonstrated that conducting simultaneous measurements of Raman scattering and photoluminescence spectra is a useful technique to understand the interaction between metal and semiconductor nanostructures. Less