In this project funded by the Chemical Structure, Dynamics and Mechanisms Program of the Chemistry Division, Professors Charles Alcock, Michael McCarthy, and Patrick Thaddeus of the Harvard-Smithsonian Center for Astrophysics will undertake spectroscopic studies of exotic carbon, silicon, and sulfur molecules, with particular emphasis on positively- and negatively-charged molecular ions. Using highly sensitive laboratory instrumentation, they seek to discover and characterize key reactive intermediates that are believed to play important roles in industrial processes, including combustion and semiconductor growth processes, and in astronomical chemistry. Such studies are of fundamental interest as well: they contribute to comparative studies of bonding between different elements in the Periodic Table, providing further evidence of the rich architecture of the chemical bond, and establish important benchmarks for theoretical chemistry. The broader impacts include integrating research and education in a setting that gives scope to student initiative and encouragement to independent investigation.
The proposed studies should have an impact in a number of areas of scientific research and technological innovation, because of the important role that carbon and silicon chemistry play in fields as diverse as combustion, materials science, and astronomy. The results of these studies may ultimately enable important industrial processes to be monitored and optimized by spectroscopic means, and lead to an improved understanding of how complex molecules can be synthesized from simple starting materials.
Work supported by the National Science Foundation under grant CHE-1058063 has resulted in the detection of new chemical species that are highly unstable, but which are implicated as key chemical intermediates in complex processes that impact the environment and human health. Many of these species are poorly characterized, and very few have been identified in any region of the electromagnetic spectrum prior to this work. These studies unambiguously establish their existence in the gas phase, and provide information on which atoms are connected by chemical bonds in the new molecule. Fundamental studies such as these impact a number of areas of scientific research and technological innovation, because of the important role that oxygen and carbon in particular play in fields as diverse as atmospheric science, combustion, biology, and interstellar space. Such studies can be used to constrain reaction parameters such as rates of formation versus destruction, and determinations of the three-dimensional structure of a molecule are essential for compiling realistic theoretical models of reactions, which are widely used in kinetic models to determine final outcomes and product distributions. Measurements undertaken as part of this award also provide information for in situ or remote sensing observations, and a firm basis for follow-up laboratory investigations in other regions of the electromagnetic spectrum can so that the physical and chemical properties of these new species can be better understood and modeled. As part of this effort, techniques have been developed to rapidly detect new chemicals based on their rotational spectra, work which has important implications for analytical testing, i.e. the identification of chemical components in a sample of unknown composition. At the interface of chemistry, physics, and spectroscopy, this type of scientific work is highly interdisciplinary, and is an excellent vehicle for integrating research and education, even at the undergraduate level. Student development is further broadened and enhanced by participation in a number of collaborations.
