论文标题
纳米颗粒簇的方向平均光散射：远场和近场基准数字群的基准
Orientation-averaged light scattering by nanoparticle clusters: far-field and near-field benchmarks of numerical cubature methods
论文作者
论文摘要
纳米颗粒的光学性质可能会受到紧凑型聚集体的组装的基本影响。对于合成并自组装成胶体形式的刚性簇而言，这是一个普遍的情况，可以在光谱应用中进一步表征或使用它们。这种实验的理论描述通常需要在所有可能的群集方向上平均光学响应，因为它们在测量过程中随机定向。这种平均通常是通过使用球形立方体方法模拟多个入射方向的光学响应来进行数值完成的。仿真时间随着方向的数量而增加，并且可能变得过于令人难以置信，但是很少有研究研究了平均准确性和计算成本之间的权衡。我们为少数范式簇几何形状的远场和近场光学响应基准了七种常用的球形立方体方法：纳米球和纳米棒的二聚体以及螺旋。与用叠加t-matrix方法获得的分析结果相比，对相对误差进行了严格评估。准确的方向平均对于与光活性，对左右圆极化光的差异响应有关的数量尤为重要，我们的示例计算特别包括远场圆形二色性和近场局部局部光学手性性。
The optical properties of nanoparticles can be substantially affected by their assembly in compact aggregates. This is a common situation notably for nanoparticles synthesised and self-assembled into rigid clusters in colloidal form, where they may be further characterised or used in spectroscopic applications. The theoretical description of such experiments generally requires averaging the optical response over all possible cluster orientations, as they randomly orient themselves over the course of a measurement. This averaging is often done numerically by simulating the optical response for several directions of incidence, using a spherical cubature method. The simulation time increases with the number of directions and can become prohibitive, yet few studies have examined the trade-off between averaging accuracy and computational cost. We benchmark seven commonly-used spherical cubature methods for both far-field and near-field optical responses for a few paradigmatic cluster geometries: dimers of nanospheres and of nanorods, and a helix. The relative error is rigorously evaluated in comparison to analytical results obtained with the superposition T-matrix method. Accurate orientation averaging is especially important for quantities relating to optical activity, the differential response to left and right circularly polarised light, and our example calculations include in particular far-field circular dichroism and near-field local degree of optical chirality.
