Magnetically Responsive Tuning of Plasmonic Nanostructures

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Metal nanoparticles can be 10,000 times smaller than the diameter of a human hair, and can be made from metals such as gold and silver. Their interactions with light make them useful for applications ranging from sensors to visual displays. While many types of particles are spherical, they can also be made into more complicated shapes. With support from the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Yadong Yin of the University of California-Riverside is developing ways to incorporate magnetic components into rod-shaped metal nanostructures. The optical properties of the hybrid structures can be controlled by applying magnetic fields, giving rise to new functionality. The discoveries from the project are advancing our ability to create new metal nanoparticles, and could have broad implications for applications such as chemical detection, biomedical sensing, and information encryption. The work is also providing training opportunities for graduate students in interdisciplinary fields. In addition, outreach to local schools and community colleges is engaging students, especially those from underrepresented groups, in research-based learning. The research team aims to develop effective approaches for fabricating plasmonic/magnetic hybrid nanostructures to achieve active tuning of plasmonic properties and explore their unique applications in photoactuation and information encryption. Three unconventional approaches are proposed, including two templating processes and one stepwise "embed and grow" process, to achieve not only the hybrid composition but also the spontaneous orientational association of the magnetic and plasmonic components. The guaranteed alignment between the plasmonic and magnetic components makes it possible to precisely tune the plasmonic excitation modes in a highly uniform and controllable manner. The resulting hybrid nanomaterials have high structural integrity and colloidal stability and can be processed in solvents or polymer matrices for fabricating functional devices. The proposal also aims to take the advantages of the angular dependent plasmonic property and the magnetic orientational alignment of the hybrid nanorods to demonstrate their uses in two unique and important applications including photoactuators and information encryption (anti-counterfeiting) devices.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.