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首页> 外文期刊>Physical review >Surface heterogeneity in Au-Ag nanoparticles probed by hyper-Rayleigh scattering
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Surface heterogeneity in Au-Ag nanoparticles probed by hyper-Rayleigh scattering

机译：超瑞利散射探测Au-Ag纳米颗粒的表面异质性

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摘要

Aqueous solutions of alloyed gold-silver nanoparticles, the diameter of which ranged between 15 and 50 nm, were prepared with varying molar fractions. The UV-Visible photoabsorption spectra for all solutions were dominated by a single surface-plasmon resonance, the wavelength of which was found to change linearly with the molar fraction. A model, in agreement with these findings, was then derived to compute a dielectric constant for the different alloyed gold-silver nanoparticles based on a weighted function of the pure gold and pure silver dielectric constants. Hyper-Rayleigh scattering measurements were performed for these alloyed metallic nanoparticles solution to determine their quadratic hyperpolarizability. Theses values, once corrected for their size and local-field factors dependencies, are found to be larger than the corresponding values for the pure gold and pure silver nanoparticles. This is attributed to the atomic surface heterogeneity of these alloyed gold-silver particles, underlining the potential of the method to investigate the surface of nanometer scale metallic particles, especially in catalysis. This atomic surface heterogeneity is assigned to the differences between the Au and Ag atoms in their interband transitions since their intraband parameters are very similar.
机译：制备具有变化的摩尔分数的直径为15至50nm的合金化金-银纳米颗粒的水溶液。所有溶液的紫外-可见光吸收光谱都由单表面等离子体共振控制，发现其波长随摩尔分数线性变化。然后，与这些发现相一致的模型被推导，以基于纯金和纯银介电常数的加权函数来计算不同合金化金银纳米颗粒的介电常数。对这些合金化的金属纳米颗粒溶液进行了超瑞利散射测量，以确定它们的二次超极化性。一旦校正了它们的大小和局部场因子依赖性，这些值被发现大于纯金和纯银纳米颗粒的相应值。这归因于这些合金化的金银颗粒的原子表面异质性，这突出了该方法研究纳米级金属颗粒表面的潜力，尤其是在催化方面。由于Au和Ag原子的带内参数非常相似，因此原子表面异质性被分配给Au和Ag原子之间的带间跃迁。

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