Abstract:

Nanoscale precision in focusing optical fields holds great promise in sensing, photodetection, spectroscopy, and optical data processing. Dispersions and assemblies of colloidal metallic nanoparticles are exceptionally well-suited when such enhancement is required at large-scales, ranging from taggants for imaging to filters, coatings, and printed components. However, meeting the manufacturing demands of these applications necessitates synthesis methods that are cost-effective, versatile, scalable, and environmentally sustainable. Recent advancements, rooted in a deeper understanding of growth mechanisms, have transformed strategies along these lines for Gold NanoSpheres (AuNS), NanoRods (AuNR), and NanoWires (AuNW). These advancements have boosted production rates more than tenfold, while enhancing precise control over particle volume and dimensions, minimizing impurities, and reducing variation in particle size. As a result, solution dispersions exhibit absorption and scattering cross-sections nearing theoretical limits while displaying higher-order multipole plasmon resonances. Highly concentrated (100+nM), formulated for specific applications, combined with techniques like blade and spray coating, as well as post-processing methods such as laser reshaping, yield films with voxelated structures. These films serve diverse functions as static and dynamic, multi-band filters, polarizers, and transparent conductors. Further understanding of scalable functionalization methods and assembly mechanisms is crucial for future development of compact sensors, optical modulators, and specialty coatings.

Biography:

Dr. Richard A. Vaia is the Chief Scientist for the Materials and Manufacturing Directorate at the Air Force Research Laboratory, where he leads internal and external research and development activities, as well as fostering a culture of innovation and establishing strategic partnerships. Rich received his PhD (1995) from Cornell University in Materials Science and Engineering and separated from the USAF as a Captain in 1999.  He has published more than 250 articles on nanomaterials, with honors including membership in the National Academy of Engineering and Fellow of Materials Research Society, American Physical Society, American Chemical Society, NextFlex, and the Air Force Research Laboratory.