金属纳米颗粒光学性质的离散偶极近似计算

采用离散偶极子近似(DDA)方法,研究了单体银纳米粒子和银纳米粒子阵列的光谱特性。研究结果发现,单体银纳米粒子的表面等离子体共振消光峰的位置随着周围介质折射率和粒子尺寸的增大逐渐红移,并且消光光谱的峰宽也越来越大。当银纳米粒子正方阵列的周期接近单体的共振波长时,阵列的消光光谱中会出现尖锐的共振峰,改变粒子尺寸的大小可以发现消光光谱中共振峰的峰值和位置有大幅度地改变,通过改变阵列在平行和垂直于入射光偏振方向上的周期,可以调节二维长方阵列共振峰的峰宽和峰位。该研究为纳米粒子在光学显微镜、生物传感元件、数据存储等领域中的应用提供有效地理论参考。

A DDA calculation on the optical properties of metal nanoparticles

The discrete dipole approximation(DDA) is used to investigate the optical properties of single metal nanoparticle and two dimensional(2D) arrays of metal nanoparticles.The calculation results show that the extinction spectrum is red-shifted with the increase of the particle size and the refraction index of the surrounding medium.The extinction spectrum of the 2D square arrays show very narrow plasmon line shapes and the resonant wavelength is only dependent on the period which is near the resonance wavelength of single nanoparticle.The resonance peak position and width of 2D square arrays are changed significantly when the size of the nanoparticles are varied.The resonance peak position and width of 2D rectangular arrays are modulated conveniently by changing the period in the direction of parallel and perpendicular to the incident polarization.An effectively theoretical reference in the field of optical microscopy,biological sensors and data storage is provided by the study of metal nanoparticles.