Collaborative Research: Structural Control of Energy Transfer in Atomically Precise Nanoclusters

With support from the Macromolecular, Supramolecular, and Nanochemistry (MSN) program in the Division of Chemistry, Professor Kenneth Knappenberger of Pennsylvania State University, Professor Christine Aikens of Kansas State University, and Professor Rongchao Jin of Carnegie Mellon University are combining advanced laser techniques with theoretical modeling and precision synthesis to study how the structure of metal nanoclusters impacts electronic and vibrational motion in these systems. Electronic and vibrational motion play key roles in determining energy flow in matter and as a result, plays a critical role in many emerging technologies. Direct correlations between structure and energy conversion are difficult to obtain because of the structural inhomogeneity typical of most materials. The research team will address this challenge by isolating atomically precise nanoclusters that can be studied with experimental and computational methods that have both electronic and vibrational state-specific resolution. These fundamental studies could impact many important technologies based on photon-to-thermal energy conversion, such as photodynamic therapy, photocatalysis, integrated circuits, mass sensing, and materials manufacturing. The knowledge gained from this work could also impact the advancement of quantum-based technologies. The project will educate graduate and undergraduate students in advanced research methods, as well as impact undergraduate and graduate students by providing research opportunities and career development activities.Structurally-precise monolayer-protected nanoclusters allow the synthesis of well defined metals that exhibit broadly tunable optical, electronic, and vibrational properties. This project is developing novel synthetic strategies to control many aspects of nanocluster structure, which include metal lattice, ligand, and valence electronic structure, particle morphology and composition. One aim of this research is to understand if electronic state lifetimes can be used to control the excitation mechanism of nanocluster acoustic modes. Success in this area could lead to high-precision nanomechanical resonators. A second aim focuses on using lattice packing structure and nanocluster shape to control vibrationally mediated photon-to-thermal energy transfer. A third aim is to understand the impacts of metal-atom substitution on chiroptical excitation and energy transfer dynamics. In each aim, structure-dependent energy transfer dynamics will be studied using time- and energy-resolved coherent multidimensional spectroscopy and theory. Metal nanoclusters spanning sub-to-few nanometer dimensions will be studied to provide information on the evolution of electronic and vibrational properties from the molecular to metallic levels. The structural specificity of the metals is expected to result in accurate structure-property correlations for electronic-vibrational coupling and chiroptical dynamics in nanoscale metals, which is necessary to accelerate progress in catalyst design, quantum information sciences, and the development of photothermal technologies.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.