Ballistic Energy Transport in Molecules

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With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) Program in the Division of Chemistry, a research team led by Professors Igor Rubtsov and Alexander Burin at Tulane University will investigate ballistic energy transport, a process that is responsible for unusually rapid and efficient movement of energy in molecules. Energy, in the form of heat, typically flows through materials through a process called thermal diffusion. However, Professor Rubtsov and his research team previously identified systems where energy deposited in one end of a molecule is rapidly transferred through the molecular backbone to distant locations. This project examines the underlying details of this anomalous transport of energy. A deeper understanding of ballistic energy transport may help scientists design new materials with improved thermal conductivity properties where the direction, speed, and efficiency of energy transport are controlled. The project also provides interdisciplinary training for graduate and undergraduate students engaged in the research, as well as opportunities for middle school students from underrepresented groups to participate in educational activities that promote chemistry. The team will use ultrafast dual-frequency two-dimensional infrared spectroscopy methods in the laboratory and will implement first-principle theoretical modeling to elucidate the efficiency, speed, and mechanisms of energy transport in a range of oligomeric chains, potentially providing access to a large library of molecular systems that demonstrate efficient energy transport. The aim of the proposed research is to understand the chemical and physical origins of the processes of formation, propagation, and detection of the vibrational wavepackets, which represent compact bundles of energy. One focus of the program is to access regimes of efficient wavepacket initiation in longer molecular chains and to explore a variety of conditions for implementing such regimes. Another focus is to investigate how electronic conjugation in oligomeric chains affects the wavepacket initiation, transport speed, and transport efficiency and to explore the ability of altering the energy transport speed and efficiency by changing the degree of the electronic conjugation by external stimuli. These studies target the development of design principles for efficient energy transporters and energy transport switches. The broader impacts of the project include advanced student training, research opportunities for students from groups that are underrepresented in science, and additional educational outreach activities for middle school students.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.