The electrostatic charge distribution model and the finite-difference time-domain method were used to provide a physically intuitive interpretation of how the shape and the number of branches affect the localized surface plasmon resonances of 3D sea-urchin like nanoparticles. We consider both planner and spherical structures with pins of cylindrical, triangular and hexagonal shape. Better alignment between surface charges of opposite sign leads to higher resonant energy states. More pin numbers provide more surface distribution area to spread dipole charges which leads to worse charges alignment and redshift of dipole mode. However, as the pin number increases, the quadrupole surface charge was pushed toward the pin tip due to Coulomb repulsion. Better charge alignment caused the quadrupole blueshift. Other effects such as convex and concave shape and dielectric materials are also discussed. Our finding may provide a designing rule to synthesize multi-branch nanoparticles for bio-chemical sensing applications.

静电荷分布模型和有限差分时域方法用于提供形状和分支数量如何影响 3D 海胆状纳米粒子的局部表面等离子体共振的物理直观解释。我们考虑具有圆柱、三角形和六边形销钉的平面结构和球形结构。相反符号的表面电荷之间更好的对齐导致更高的共振能态。更多的引脚数提供更多的表面分布区域来传播偶极电荷，这导致更差的电荷对齐和偶极模式的红移。然而，随着引脚数的增加，由于库仑排斥，四极表面电荷被推向引脚尖端。更好的电荷对齐导致四极杆蓝移。还讨论了其他影响，例如凸凹形状和介电材料。我们的发现可能为合成用于生化传感应用的多分支纳米粒子提供设计规则。