三角形金属纳米粒子的光力特性研究

Study on Optical Force Characteristics of Triangular Metal Nanoparticles

基于麦克斯韦应力张量理论,对多边形金纳米粒子在聚焦场下的光力特性进行了研究。以三角形金纳米粒子为例,从粒子在聚集场中的受力情况出发,分别研究了具有圆对称能量分布的聚焦场和具有三角形能量分布的聚焦场对三角形金纳米粒子的捕获特性。研究结果表明,当使用圆对称聚焦场时,可对边长为50~350 nm的三角形金纳米粒子实现稳定捕获;当使用三角形聚焦场时,在粒子以和聚焦场形状匹配的角度进入聚焦场的情况下,可对边长为100~350 nm的三角形金纳米粒子实现稳定捕获。将圆对称聚焦场和三角形聚焦场对三角形金纳米粒子的捕获特性进行比较,发现三角形聚焦场在x方向的捕获力要强于圆对称聚焦场;而在y方向,三角形聚焦场对粒子的捕获范围要大于圆对称聚焦场。该工作研究了三角形的金属纳米粒子在不同形状聚焦场下的光力捕获特性,为基于非球形金属粒子的光学操纵在拉曼光谱超分辨成像、粒子微加工等领域的应用奠定了理论基础。

Based on Maxwell’s stress tensor theory,the photodynamic properties of polygonal gold nanoparticles in a focused field were studied.Taking triangular gold nanoparticles as an example,the trapping characteristics of triangular gold nanoparticles in focusing field with circular symmetric energy distribution and with triangular energy distribution were studied respectively from the stress conditions of the particles in the focusing field.The results show that the triangular gold nanoparticles with side length of50~350 nm can be stably captured by using the circular symmetric focusing field.When the triangular focusing field is used,the triangular gold nanoparticles with side length of 100~350 nm can be stably captured under the condition that the particles enter the focusing field at an angle matching the shape of the focusing field.The trapping properties of triangular gold nanoparticles were compared between the circular symmetric focusing field and the triangular focusing field,and we found that the trapping force of the triangular focusing field in the x direction was stronger than that of the circular symmetric focusing field.In the y direction,the capturing range of the triangular focusing field is larger than that of the circular symmetric focusing field.In this work,we studied the optical trapping properties of triangular metal nanoparticles in different focused fields,and laid a theoretical foundation for the application of optical manipulation based on non-spherical metal particles in Raman super-resolution imaging,particle microprocessing and other fields.