In this paper, we explore the ability of ellipsometry to characterize colloidal suspensions composed of gold nanoparticle (NP) chains. The complex effective index of these suspensions is deduced from ellipsometric measurement by using a wavelength-by-wavelength inversion without any dispersion law. We show that the effective refractive index of these colloids is defined by the nature of the solvent, whereas their effective extinction coefficient is mainly sensitive to the plasmonic properties of NP chains. The influence of the NP radius distribution and arrangement on the effective extinction coefficient of NP chain are investigated through simulations based on the coupled point dipole method (CDM). We clearly show that this coefficient is mainly sensitive to the interparticle distance and the number of NPs in the longest segment of chains. We demonstrate that the distribution of the number of NPs in the longest segment of chains and their volume fractions can be directly deduced from the ellipsometry by using the CDM.

中文翻译：

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金纳米粒子链：合成，表征和建模使用光谱椭偏仪

在本文中，我们探索了椭圆光度法表征由金纳米颗粒（NP）链组成的胶体悬浮液的能力。这些悬浮液的复数有效指数是通过椭圆偏振法测量得出的，方法是使用波长逐波长反演而没有任何色散定律。我们表明，这些胶体的有效折射率是由溶剂的性质决定的，而它们的有效消光系数则主要是对NP链的等离子体性质敏感。通过基于耦合点偶极子法（CDM）的仿真研究了NP半径分布和排列方式对NP链有效消光系数的影响。我们清楚地表明，该系数主要对最长链段中的粒子间距离和NP数量敏感。