Metallic nanoparticles can be created in a variety of different shapes. The loosely held electrons in these small particles, which can be pushed around by light, slosh around like waves in a pool. As the light intensity increases, these waves (called plasmons) become bigger, and with enough energy they can cause chemical reactions. The particle's shape can also affect the size of the plasmon waves, with corners creating bigger waves than other parts of the particle. As a result, particles with sharp features are desired. One strategy for creating these complicated structures is to use light to promote the growth. The problem is that the mechanism by which these sharp features form is not understood, and therefore difficult to control. With support from the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program in the Division of Chemistry, Professor Wei David Wei at the University of Florida is exploring the light-driven growth of Ag nanostructures with prismatic shapes. Insights gained from the project could lead to new materials, advancing technologies that range from cancer therapies to solar energy conversion. The project is also providing training opportunities for the next generation of scientists, as well as educating high school students, teachers, and the general public on plasmonic nanomaterials. Professor Wei also plans to develop radio modules in Spanish to bring general science to groups historically underrepresented in the scientific community in Florida.
Working with his students, Professor Wei is exploring the role of the surface plasmon resonance (SPR) in driving the growth of Ag nanoprisms. The process starts with spherical Ag nanoparticles, which are then exposed to an intense light source. The team then watches the particle grow using transmission electron microscopy (TEM) methods and electron energy loss spectroscopy (EELS), and computer simulations aid in the interpretation of the experimental data. Observations at the single-nanoparticle level provide a detailed view of the underlying photophysical and chemical processes regulating the plasmon-driven synthesis of the Ag nanoprisms. The project is exploring the importance of a cooperative interplay between surfactants and metal SPR to effectively harness plasmon-driven photochemistry for nanomaterials synthesis. The molecular-level insights obtained in this project not only lay the groundwork for the design and construction of other types of shape-controlled plasmonic nanostructures, but more importantly, their implications benefit a broader field of plasmonic photochemistry beyond nanomaterials synthesis.
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.
