Chemistry and Materials Science Seminar: The Role of UV Photolysis and Thermal Processing in Interstellar Ice Chemistry

Chemistry and Materials Science Seminar
The Role of UV Photolysis and Thermal Processing in Interstellar Ice Chemistry

Dr. Susanna L. Widicus Weaver
Vozza Professor of Chemistry & Astronomy
University of Wisconsin-Madison

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This seminar may be attended in person in 2300 Gosnell Hall or online via Zoom.

Abstract:
It has been shown through both laboratory and observational studies that direct and cosmic-ray induced UV photodissociation drives a complex network of chemistry in interstellar ices. Astrochemical models have demonstrated that gradual heating of these UV-processed ices during star formation can lead to a wide variety of complex organic molecules. Additional modeling and observational studies have shown that these molecules are likely incorporated into protoplanetary disks and participate in the chemistry of planet formation. These processes could therefore serve as molecular starting points for prebiotic chemistry in the universe. Our observations of the chemistry of star-forming regions have shown that there is wide variation in the chemical compositions of hot cores, and that methanol photodissociation on icy grains may be the key process feeding the formation of larger prebiotic molecules. To test possible chemical routes in interstellar ices, we have built a novel laboratory experiment that couples the traditional tools of ice studies – FTIR spectroscopy and mass spectrometry – with the structure specificity of rotational spectroscopy. Such measurements can provide the “ground truth” to guide observations of star- and planet-forming zones. This novel experimental approach has been benchmarked with pure ice studies of water and methanol, and initial photoprocessing results for a pure methanol ice have been obtained. A complex network of organic chemistry was observed and offers fascinating hints at the processes driving interstellar prebiotic chemistry. Our ongoing studies are designed to investigate mixed ices of varying ratios of water and methanol to better simulate interstellar chemistry. In this talk I will present both the observational and laboratory studies and discuss these results in the context of prebiotic astrochemistry.

Speaker Bio:
Susanna Widicus Weaver, Vozza Professor of Chemistry and Astronomy at the University of Wisconsin is an expert in prebiotic astrochemistry. Her research, combining laboratory spectroscopy, observational astronomy, and chemical modeling, is aimed at understanding the mechanisms driving interstellar chemistry and the pathways for the formation of life. She received a bachelor’s degree in chemistry at Illinois Wesleyan University (2000) and her Ph.D. in chemistry at Caltech (2005). She was a postdoctoral fellow in Chemistry and Astronomy at the University of Illinois from 2005-2008. Before moving to Wisconsin, she was a Professor of Chemistry at Emory University. She is a passionate teacher and leads an active and diverse research group involving many students (https://widicusweaver.chem.wisc.edu).

Intended Audience:
Undergraduates, graduates, experts. Those with interest in the topic.

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