论文标题
使用离散的偶极近似值模拟电子介质中的电子损失光谱和阴极发光的颗粒
Simulating electron energy-loss spectroscopy and cathodoluminescence for particles in arbitrary host medium using the discrete dipole approximation
论文作者
论文摘要
电子损失光谱（EEL）和阴极发光（CL）是广泛使用的实验技术，用于表征纳米颗粒。离散偶极近似（DDA）是一种数值精确的方法，用于模拟电磁波与任意形状和内部结构颗粒的相互作用。在这项工作中，我们扩展了DDA，以模拟鳗鱼和Cl，以嵌入任意（甚至吸收）无界宿主培养基中的颗粒。后者包括密集培养基的情况，支持电子的Cherenkov辐射，这在鳗鱼模拟中从未考虑过。我们基于音量综合方程式建立了一个严格的理论框架，最终表达式在开源软件包ADDA中实现。该实现与真空中的球形和中等密度的宿主培养基中的球形理论和边界元素方法一致。它成功地重现了封装在有限底物中的颗粒的已发表实验。在中度密集和Cherenkov案例中显示了后者 - $ \ text {sio} _ {\ text {2}} $中的金纳米棒，以及分别为$ \ text {sin} _ {\ text _ {\ text {x}} $的银球。
Electron energy-loss spectroscopy (EELS) and cathodoluminescence (CL) are widely used experimental techniques for characterization of nanoparticles. The discrete dipole approximation (DDA) is a numerically exact method for simulating interaction of electromagnetic waves with particles of arbitrary shape and internal structure. In this work we extend the DDA to simulate EELS and CL for particles embedded into arbitrary (even absorbing) unbounded host medium. The latter includes the case of the dense medium, supporting the Cherenkov radiation of the electron, which has never been considered in EELS simulations before. We build a rigorous theoretical framework based on the volume-integral equation, final expressions from which are implemented in the open-source software package ADDA. This implementation agrees with both the Lorenz-Mie theory and the boundary-element method for spheres in vacuum and moderately dense host medium. And it successfully reproduces the published experiments for particles encapsulated in finite substrates. The latter is shown for both moderately dense and Cherenkov cases - a gold nanorod in $\text{SiO}_{\text{2}}$ and a silver sphere in $\text{SiN}_{\text{x}}$ respectively.
