Optical spectra of silicon-bearing clusters and nanostructures of astrophysical interest

• Applicant: Professor Dr. Otto Dopfer
• Subject Area: Astrophysics and Astronomy
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 431702392

We propose in this renewal proposal to continue our efforts in determining the structural and electronic properties of small silicon-bearing clusters and nanostructures, especially those of astrophysical relevance, by means of sophisticated vibrational and optical laser spectroscopy and quantum chemical calculations. The chemical evolution from small silicon oxides, silicates, and related molecules to large micrometer-sized silicate dust particles in the interstellar medium is poorly understood. Intermediates between these size regimes must exist but are elusive to observations. Laboratory optical spectra of these species are unavailable in the literature, and the purpose of this project is to fill this gap by determining the optical and photochemical properties, stabilities, photofragmentation patterns, and chemical reactivity of these species. Based on our first promising pioneering results on small polyatomic silicon oxide and carbide clusters in the first funding period, we continue our efforts toward larger clusters and higher-resolution spectra. For this purpose, we will implement a new cryogenic ion trap into the available laser-vaporization tandem mass spectrometer setup, which will significantly enhance the performance of the spectroscopic approach with respect to both spectral resolution and sensitivity. Our results may not only foster the interstellar detection of those particles but also provide valuable input to theoretical models of circumstellar dust shells. While we concentrate herein on the astrophysical context of silicon oxides, silicates, and related molecules, the species under investigation are also of interest in other fields, such as semiconductor and materials sciences, nanophotonics, and catalysis. The optical properties of these species also provide invaluable experimental benchmark data for developing, improving, and testing quantum chemical approaches for the reliable prediction of excited states, an ongoing challenge in quantum chemistry.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Alexander Axel Breier