Quantifying the Optical Rotation of Light by Chiral Plasmonic Nanostructures
Abstract
Chiral light (plane waves with circular polarization) may be useful for initializing well-defined qubits for quantum computing, establishing anti-counterfeit measures, or performing enantioselective synthesis. Currently, chiral optical signals at visible wavelengths are both challenging to create and detect. In nature, optically active molecules display asymmetry mainly in the ultra-violet regime (e.g. amino acids or biological substances), while lithographic limitations result in metamaterial resonances that typically extend beyond the near-infrared (NIR). The equipment requested in this proposal would enable the design and synthesis of new nanostructures that offer a potential solution to this materials problem. Colloidally synthesized chiral plasmonic nanostructures may address the paucity of materials optically active in the visible and NIR wavelengths since metal particles with dimensions on the nanometer scale absorb and scatter strongly in this part of the electromagnetic spectrum. The equipment requested in this proposal would enable the optical asymmetry induced by chiral plasmonic nanostructures to be quantified. When these plasmonic enantiomers (objects not superimposable on their mirror image) interact with light, their asymmetric electronic absorptions can be measured by circular dichroism (CD); and their scattering by circularly polarized luminescence (CPL) spectrophotometers. The CD and CPL spectrophotometers requested in this proposal will enable fundamental structure-property relationships to be explored, important for understanding the mechanism by which circularly polarized light creates hot electrons in silver nanorods or gold nanobipyramids that photodeposit material at hot spots to form enantiomers. The results enabled by this equipment will also guide theorists in formulating models for understanding these light-matter interactions, e.g. if chiral evanescent electromagnetic fields are involved, or the role of defects in directing the spatial distribution of hot electrons. The spectrophotometers requested will be used to record the differential absorption and emission-scattering of circularly polarized light by chiral plasmonic nanostructures. The equipment requested will not only enable new experiments at the University of Utah, but also in the surrounding Intermountain West, including, but not limited to the neighboring states of Idaho, Wyoming, Nevada, etc. This is especially important for circularly polarized luminescence measurements since no turnkey spectrophotometers are found in the state of Utah and the surrounding states. The new research capabilities rendered by these two spectrophotometers are expected to advance the scientific and engineering efforts in the Intermountain West funded by the Department of Defense.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 29, 2024
- Source ID
- FA95502310146
Entities
People
- Ming Tang
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Utah