Electronic spectroscopy of astrophysically important silicon-bearing molecules

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Molecules containing silicon are key reactive intermediates and are thought to be the progenitors of dust in evolved stars. This research project will generate new spectroscopic data on small silicon carbides – molecules containing silicon and carbon – that reside in the dust-forming regions and circumstellar envelopes of evolved carbon stars. Results from the study will allow determination of the structures and properties of these molecules and expedite laboratory searches at radio and infrared wavelengths. This will permit their unambiguous identification in space, allowing astronomers to better understand the conditions within circumstellar environments and shed some light on the poorly understood nature of interstellar dust. This project will contribute to the professional development of a postdoctoral scholar, train graduate students in advanced methods of laboratory astrophysics, provide research opportunities to undergraduate students, and expose local public high school students from non-traditional backgrounds to cutting edge research in spectroscopy.Using advanced laser spectroscopy techniques, including two-dimensional laser induced fluorescence (2DF) and stimulated emission pumping (SEP), the investigators will study the electronic spectra of SiC2, Si2C, and other silicon-bearing transient molecules. Exploiting the strong optical transitions of these molecules, SEP will provide a broad overview of rovibrational transitions within highly excited vibrational levels, yielding spectroscopic constants of sufficient accuracy to significantly reduce the frequency range required for laboratory microwave searches. Similarly, 2DF will be used to unravel the complex optical spectrum of Si2C and expedite searches for non-polar or weakly polar silicon-bearing molecules or ones containing other abundant circumstellar elements. Complementary mass-resolved resonant ionization experiments will be used to secure the molecular identifications. Some of the molecules investigated are also important in thin film fabrication, so a knowledge of their optical spectra could help elucidate and improve the manufacturing processes of advanced optical and electronic devices.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.