NER: Directed and Selective Self-Assembly of Nanosized Particles via Surface-Plasmon Excitation

NER: Directed and Selective Self-Assembly of Nanosize Particles via Surface-Plasmon Excitation - Hastings, Menguc, and Crofcheck Project Summary Intellectual Merit: Understanding and implementation of active, directed assembly of metallic nanoparticles is crucial for the future of nanotechnology. Nanosized metallic particles have unique optical and electronic properties, which make them very desirable building blocks for applications in bio-chemical sensing, communications, medicine, and electronics applications. A robust method that enhances and directs the self-assembly of metallic particles is an extremely viable and exciting goal. This research exploits the unique optical and thermal properties of metallic nanostructures to selectively direct their assemble into active nanodevices. This project represents the first step toward a general-purpose nanoassembly technology, but will also explore fundamental issues in nanoscale electromagnetics and thermodynamics. The major goal in the proposed study is to design, construct and operate a system that selectively and locally fuses nanoscale particles into coherent structures using an atomic force microscopy (AFM) probe and surface-plasmon excitation. The system relies on the optical excitation of particles under surface-plasmon resonance (SPR) conditions and then localizes additional energy via the AFM probe to fuse the particles together. Due to the unique thermal properties of metallic nanoparticles the surfaces of the particles will melt at temperatures dramatically lower than the bulk melting temperature to permit particle fusion. The nature of SPR allows the particles to be selectively excited based on size, material, and local microscopic environment, opening the door for an integrated process that permits multiple materials to be fused and patterned in the same time frame. There are three primary objectives of the proposal: (1) understand surface-plasmon excitation of nanoparticle/nanoprobe systems, (2) understand the conditions necessary for selective nanoparticle heating, surface melting, and fusion, and (3) experimental demonstration of selective excitation and fusion of nanoparticles in an atomic force microscope. This system represents a bridge between the second and third generation of nanotechnology- evolving active nanosystems for a three-dimensional manufacturing process. Broader Impact: The proposed investigation of nanoparticle-nanoprobe systems will have a far reaching impact on the understanding of nanoscale electromagnetics and thermodynamics. Establishing a framework for a new nanoscale assembly technique will also have broad impact by enabling new active nanodevices and by making nanoassembly technology more widely available. Even a partially successful outcome will highlight the limitations involved when using the unique optical and thermal properties of nanosize metallic materials for directed or self assembly. In the future, this work can be extended to other optically excited nanostructures such as semiconductor quantum dots, and the methodology can be extended to mass-production of active nanodevices by using multiple nanoprobe arrays.. The proposed program will directly support two graduate students, who will receive extensive training in nanomaterials research and modeling. The University of Kentucky has two Nanotechnology Programs: the Nanoscale Engineering Certificate Program (NECP) and the Umbrella Program for Nanotechnology (UPoN). These programs promote active learning by understanding the processes and implications of nanotechnology and creating communication between engineering disciplines within the context of nanotechnology. The project will draw on students and researchers from within these communities. The proposed research program addresses the research and education themes of Fundamental Nanoscale Phenomena and Processes in Active Nanostrnctures and Nanoscale Devices and System Architecture.