Collaborative Research: Metasurface-Enabled Broadband Circular Dichroism Spectroscopy and Imaging

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Peijun Guo and his group at Yale University and Xingjie Ni and his group at Pennsylvania State University are collaboratively advancing the characterization of chiral molecules (i.e. molecules that display handedness) and materials. Circular dichroism (CD) is an optical property that can be used to probe molecular chirality. The Guo/Ni team is engineering metasurfaces – structures that can manipulate various properties of light, including its chirality – to significantly simplify CD spectrometers, thereby facilitating CD spectroscopy and imaging experiments with remarkable sensitivity and high throughput. The project offers hands-on training to both graduate and undergraduate students in areas of nanofabrication, light-matter interactions, and the assembly and adaptation of advanced optical measurement setups. Moreover, the project aims to motivate younger students to venture into STEM (science, technology, engineering and mathematics) fields by partnering with the Yale Pathways and the Office of Science Outreach at Penn State to engage K-12 students to the research. This collaborative project focuses on the design, fabrication, and evaluation of metasurfaces for a novel approach to circular dichroism (CD) measurements. The metasurfaces are designed to span wavelengths ranging from the ultraviolet to terahertz, portions of which are presently not covered by commercial CD spectrometers. Several prototypical chiral systems, including chiral molecules, chiral colloidal nanocrystals, and chiral two-dimensional hybrid perovskites, are being used for benchmarking the metasurface-enabled optical tools. The metasurfaces are intrinsically diffractive, hence they enable single shot-compatible CD characterization, making them invaluable for monitoring irreversible chemical processes. The metasurfaces can be incorporated in other optical measurement techniques such as magneto-optic Kerr effect and time-resolved Faraday rotation. These techniques offer powerful probes for understanding chemical synthesis and catalysis, energy conversion, and quantum information science. Students involved in this project will acquire a profound understanding of nanophotonics, optical spectroscopy, and imaging methods, offering them valuable, practical insights into these rapidly evolving scientific fields. 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.