Radiataive and Ultrafast Non-radiative Electronic Relaxation in Individual and Assembled Noble Metallic Nanopartiacles of Different Shapes

本项目主要研究纳米尺度下的材料性质与体性质不同，材料性质随其尺寸或形状的变化而变化。它解决了单个金和银纳米粒子的非辐射特性以及粒子间耦合对这些特性的影响。电子束光刻技术的一项新技术能够产生小至几纳米的纳米粒子，该技术将用于研究随着尺寸、形状和粒子间距离的变化，弛豫过程和相干晶格振荡周期（由飞秒电子激光激发产生）的变化。衬底对颗粒间耦合的影响也将被研究。这些性质的变化将使我们了解这些组合粒子的耦合性质。这个项目更广泛的影响是教育和工业性质。例如，关于单个贵金属纳米颗粒的性质，随着它们的大小和形状的改变，它们散射和吸收光的能力会发生强烈的变化，而这些性质可以用来记录单个癌细胞的清晰图像。这些纳米粒子的另一个特性是，强烈吸收的光能迅速转化为热能，这种特性可以通过使用对健康细胞无害的极低水平的激光辐射来选择性地摧毁癌细胞。因此，了解单个纳米粒子的特性可以实现新的应用，在这些领域受过培训的学生在与纳米技术广泛领域相关的学术、工业和国家实验室就业市场上非常有竞争力。

This project focuses on the nanometer size scale where material properties differ from bulk properties and change as their size or shape changes. It addresses nonradiative properties of individual gold and silver nanoparticles and the effects of interparticle coupling on these properties. A new capability in electron beam lithography capable of producing nanoparticles as small as few nanometers will be used to focus on changes in relaxation processes and the period of the coherent lattice oscillations (produced by femtosecond electronic laser excitations) as the size, shape and the interparticle distances change. The effect of the substrate on interparticle coupling will also be examined. The changes in these properties will give an understanding of the nature of the coupling of these assembled particles.The broader impacts of this project are both educational and industrial in nature. For example, with regard to the properties of individual Noble metal nano-particles, as their size and shape changes their ability to scatter and absorp light strongly changes, and these properties can be used to record clear images of single cancer cells. Another property of these nanoparticles is that strongly absorbed light energy is rapidly converted into heat, a property that can be used to selectively destroy cancer cells by using a very low level of laser radiation that is not harmful to healthy cells. Thus understanding properties of individual nanoparticles enables novel applications, and students trained in these areas are very competitive in the academic, industrial and National Laboratory job markets related to broad fields of nanotechnology.