With this Renewal Award, the Chemical Structure, Dynamics, and Mechanisms Program continues to support Professor Robert J. McMahon of the University of Wisconsin-Madison in a project involving investigations of fundamental issues in structural and mechanistic organic chemistry of relevance to astrochemistry. The project will explore the structure, reactivity, and spectroscopy of carbon-rich molecules that are hypothesized to play a role in the chemistry of interstellar clouds, protoplanetary nebulae, circumstellar shells, and the atmosphere of Titan. The PI and his students and collaborators will generate these energetic species, determine their spectroscopic properties, investigate their thermal and photochemical reactivity and attempt to detect them as constituents of interstellar space. This interdisciplinary program will utilize the techniques of synthetic organic chemistry, molecular spectroscopy, quantum chemistry and observational astronomy to obtain a deeper understanding of the organic chemistry occurring in interstellar space.
This project, which cuts across numerous disciplines including fundamental organic chemistry, astrochemistry and combustion chemistry, will train graduate and undergraduate students in the techniques of organic synthesis, matrix isolation, and molecular spectroscopy.
This research program explores fundamental aspects of organic chemistry with the goal of providing an understanding of the chemistry that occurs in space. The study of the chemistry of space is known as astrochemistry. People understand that space is comprised of stars and planets, but they do not appreciate that the very same chemical substances that exist on Earth also exist throughout our Universe. We know this fact, unequivocally, because we are able to detect and measure the characteristic features of these molecules. Even though it is not possible to collect samples of these substances and put them in bottles, we know, with certainty, that they exist in space – hundreds of light-years distant from Earth. In order to detect molecules in space, it is first necessary to measure their characteristic features in laboratory experiments here on Earth. Only after these features have been measured (on Earth) do astronomers ‘know what to look for’ in order to detect these molecules in space. At the current time, over 150 different molecules have been detected in space. This may seem like a large number, but it is a very small fraction of the millions of different compounds that are known on Earth. We are, however, on the verge of profound discoveries involving the detection of some of the simplest prebiotic molecules – the molecules of life! Our research program builds from an extensive background in organic chemistry. We draw on our expertise to identify key targets for detection in the complex chemistry of interstellar space. Our ideas can be experimentally tested through an interdisciplinary program that draws on synthetic organic chemistry, molecular spectroscopy, quantum chemistry, and astronomy. With support from the NSF, we built a sophisticated instrument that allows us to measure the characteristic features of our target molecules, in the hope of detecting them in space. The scientific impact of the proposed research reaches beyond chemistry and cuts across diverse areas of contemporary science. In the area of astrochemistry, the program addresses fundamental questions concerning the nature of what is now recognized to be the dominant reservoir of organic compounds in the universe. A deeper understanding of the organic chemistry of space may carry implications concerning the origin of life. Studies may also provide insight concerning the atmosphere on primitive Earth and on Titan, the largest moon of Saturn. In the area of combustion chemistry, the program tests key hypotheses concerning the chemical mechanism of soot formation. The fundamental chemical studies enable advances in disciplines throughout the physical sciences. The program supports the education of graduate and undergraduate students. Research collaborations provide an environment for training the next generation of students in the study of complex chemical problems as part of an interdisciplinary research team. Training in mechanistic organic chemistry provides a valuable foundation for subsequent careers in industry or academia. Half of the PI’s former coworkers are employed in the chemical or pharmaceutical industry, half hold faculty positions in academia. Of the fifteen current or recently-completed Ph.D. students in the PI’s research group, seven are women. The PI’s involvement in recruiting a diverse group of both faculty and graduate students to the program at Wisconsin has been decisive in several cases, and he has been a major contributor in developing the Department’s Plan for Broadening Participation. The PI and coworkers continue their engagement in a variety of science education and outreach activities.
