外围介质介电常数对金纳米棒光学性质影响的数值模拟

采用电化学方法制备出悬浮胶体金纳米棒。在室温下测得其紫外-可见吸收光谱和荧光发射光谱。结合准静电场理论与散射理论对金纳米棒的光学特性进行了数值模拟。计算结果表明，由于金纳米棒形状的各向异性，吸收截面与散射截面均出现两个共振峰，分别对应于横截方向与长轴方向的表面等离子共振。对于几何形状一定的金纳米棒，在外围介质介电常数从1.5增加到2.5的过程中，两个共振吸收峰均增强并非线性红移。然而对于散射光谱，短波方向的共振峰线性红移，强度变化微弱;长波方向的共振峰减弱并非线性红移。

Simulation of the Medium Dielectric Constant Dependent Optical Properties for Gold Nanorods

Suspended gold nanorods were synthesized via electrochemical method. UV-Vis ible spectra and fluorescence emission spectra were measured at room temperature . Numerical calculations based on quasi-static and scattering theories were de veloped to describe these observed optical properties. Because of the anisotropy of the gold nanorods, both absorption features and scattering features show two peaks, which result from the transverse and longitudinal surface plasmon resona nces respectively. Furthermore, with increasing the dielectric constant of surro unding medium from 1.5 to 2.5, these two absorption peaks increase and red shi ft in a nonlinear way together. However, the scattering peak at the shorter wave length depends on the surrounding medium dielectric constant in a linear fashion , and the other scattering peak at the longer wavelength decreases and red shift s nonlinearly.