Spectroscopy of Carbon Cluster Cations

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

With support from the Chemical Structure, Dynamics, and Mechanisms A (CSDM-A) program of the Chemistry Division, Professor Michael Duncan and his students at the University of Georgia will study small carbon molecules. The molecular-level understanding of structure and function of carbon materials are ongoing challenges for chemistry and engineering. Carbon fibers, graphene sheets, or fullerene cages have applications as materials for microelectronics and solar energy generation, and metal-carbon materials form the basis for modern battery technology. Carbon molecular ions are likely present in interstellar gas clouds, playing an important role in astrochemistry. This project explores new ways to make carbon molecules and employs laser spectroscopy to determine their structures and bonding properties. The insights gained facilitate the design and understanding of carbon-based materials. The work trains students in laser and vacuum technology, electronics, spectroscopy, mass spectrometry, and computational chemistry, preparing them for careers in the chemical industry, university faculty positions, or as scientists in government labs. Professor Duncan also mentors early-career professors, many of them members of underrepresented groups, to help them develop new approaches for physical chemistry laboratory experiments. This research investigates molecular carbon cluster cations and their chemical interactions with metal atoms and small molecules. Cold carbon cluster ions and their complexes are produced in the gas phase with laser vaporization coupled to a supersonic molecular beam. The collision-free environment allows intrinsic structures unperturbed by liquid or solid surroundings. Ions with a specific composition are selected with a mass spectrometer, and their structures are studied with infrared and UV-visible laser spectroscopy, complemented with computational quantum chemistry. Characteristic spectral patterns are measured in the infrared region for carbon framework vibrations and those of molecular adsorbates. Broadly tunable UV-visible lasers allow new studies of electronic spectroscopy. Photofragment imaging experiments complement the spectroscopy, revealing bonding energetics. These experiments yield new chemical insights into electronic structure and bonding and provide benchmarks for computational quantum chemistry which predicts structures, vibrational patterns, and excited electronic states. 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.