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

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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.