The objective of this research project is to develop versatile methods for self-organization of metal nano-architectures where colloidal solutions of metal nanoparticles are assembled on self-organized chemical domains using covalent nanoparticle-substrate interactions. The assembly process to be developed allows for control of nanoparticle size, composition and shape, number of nanoparticles assembled in a cluster as well as array architecture. The chemical domain diameter to nanoparticle diameter ratio will be investigated as a means to control the cluster size. A balance between capillary and double layer forces yields molecular scale separations between nanoparticles in clusters that is important to yield enhanced optical fields. The inter-particle spacing and cluster size will be varied to tune resonances and local enhancement of optical fields. Models for investigating local and collective resonances in clustered or arrayed nanoparticles will be developed, including the local density of states, and extinction and absorption coefficients.
None of the standard nanoscale lithographic techniques such as focused ion-beam, electron beam and nano-imprint lithography, are easily translated into large-area production that is needed to transform proof of concepts into commercial products. In contrast, guided self-organization is designed here to be inexpensive and scalable to large-area production. Facile, large-area synthesis of ordered arrays of metal nanostructures will enable or enhance performance in several critical technologies. Partnerships with industrial and government laboratories are included to test metal nanosystems in sensor, laser and detector applications. For example, plasmonic nanoparticle clusters will be used to lower detection limits in optical based sensors that is needed in both biomedical applications and in explosive agent detection. The research program will also directly contribute to the education of graduate and undergraduate students through hands-on laboratory experience in a field that is at the forefront of modern research. Outreach activities will include integrating local high school students in research activities to increase science, technology, engineering, and math enrollment of underrepresented groups.
