CAREER: Detecting Quantum Signatures in Nonadiabatic Molecular Dynamics

With support from the Chemical Structure, Dynamics, and Mechanisms A (CSDM-A) program in the Division of Chemistry, Melanie Reber of the University of Georgia is developing methods capable of measuring transient changes in the absorption spectra of molecules in the gas phase. Gas phase measurements, specifically in a molecular beam, allow for detailed study of the role of vibrations in excited state processes with a direct comparison to theoretical predictions. Molecular beams provide a cold and controlled environment for generating and studying small molecules but require high detection sensitivity due to the low number densities. Professor Reber and her students will use optical enhancement cavities to increase the detection sensitivity of ultrafast transient absorption spectroscopy. Their discoveries could lead to a more complete understanding of conical intersections in vibrational excited states of organic molecules and radicals. As part of the educational component, Dr. Reber will explore how the use of art and music in teaching science impacts student learning and retention of students from all backgrounds. The students involved in the project will gain highly technical training in lasers, optics, and electronics relevant to a range of high technology fields including quantum technologies. To broaden participation and awareness of the interdisciplinary fields of physical chemistry and quantum science, Dr. Reber will teach a class for incoming first-year undergraduate students to introduce them to the science, technology, and application of quantum science. The project will look at the molecular dynamics around conical intersections with both ultrafast time resolution and high spectral resolution for a detailed characterization of the dynamics. This includes the development of new instrumental techniques that study ultrafast dynamics of molecules in the gas phase with both ultrafast time resolution and high-resolution detection. The team uses ultrafast frequency comb fiber lasers in the visible and infrared spectral regions and couples them to external optical enhancement cavities to increase the signal. This enables study of dilute species in molecular beams with ultrafast transient absorption spectroscopy. Dual comb detection techniques will be developed to provide quantum-state resolution on the absorption spectra of the resultant species. The overarching objective is to study conical intersections in excited electronic states and conical intersections between vibrational states, such as Jahn-Teller interactions. This study aims to provide a detailed description of the dynamics in the gas phase for direct comparison with theory and a more complete picture of the quantum effects in the dynamics. 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.