近接触金属纳米粒子中的等离子体激元：接触二聚体极限下的奇异响应
Plasmons in nearly touching metallic nanoparticles: singular response in the limit of touching dimers
摘要：
从理论上研究了金纳米粒子二聚体在粒子接触极限附近和之外的响应。当粒子彼此接近时，观察到主导偶极特征，该特征由于粒子间耦合而被推入红外，并且与粒子间间隙中的感应电荷的大量堆积相关。随着粒子间距的减小，红移变得奇异。当穿过粒子间间隙的耦合变得如此之强以至于偶极振荡被抑制时，对于非常小的分离，响应减弱。较低的波长，高阶模式显示出类似的分离依赖性，在几乎接触的二聚体。接触后，观察到奇异行为，通过一个新的红外吸收峰的出现，也伴随着巨大的电荷堆积在粒子间的结，如果初始粒子间的接触是在一个单一的点。这种新的模式是明显不同于分离的二聚体的最低模式。当通过平坦表面之间的接触形成结时，结处的电荷被中和，并且模式演化通过接触是连续的。计算出的奇异响应解释了最近的实验金属纳米粒子二聚体，并在纳米粒子为基础的传感器和等离子体激元电路的设计有关。
英文摘要：
The response of gold nanoparticle dimers is studied theoretically near and beyond the limit where the particles are touching. As the particles approach each other, a dominant dipole feature is observed that is pushed into the infrared due to interparticle coupling and that is associated with a large pileup of induced charge in the interparticle gap. The redshift becomes singular as the particle separation decreases. The response weakens for very small separation when the coupling across the interparticle gap becomes so strong that dipolar oscillations across the pair are inhibited. Lower-wavelength, higher-order modes show a similar separation dependence in nearly touching dimers. After touching, singular behavior is observed through the emergence of a new infrared absorption peak, also accompanied by huge charge pileup at the interparticle junction, if initial interparticle-contact is made at a single point. This new mode is distinctly different from the lowest mode of the separated dimer. When the junction is made by contact between flat surfaces, charge at the junction is neutralized and mode evolution is continuous through contact. The calculated singular response explains recent experiments on metallic nanoparticle dimers and is relevant in the design of nanoparticle-based sensors and plasmon circuits.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
