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Description
Sulfur (S) is of high interest in context of (astro)chemical evolution and habitability. However, the origin of S-bearing organic compounds in the Solar System is still not well-constrained. We tested by laboratory experiments whether complex organosulfur compounds can be formed when surfaces of icy Solar System bodies are submitted to high-energy S ions. Methods. Non-S-bearing organic residues, formed during the processing of astrophysical H_2_O:CH_3_ OH:NH_3_-bearing ice analogs, were irradiated with 105 keV-S 7+ ions at 10K and analyzed by high-resolving FT-ICR-MS. Resulting data were comprehensively analyzed, including the tools of network analysis. Out of many thousand detected compounds, 16% contain at least one sulfur atom (organosulfur (CHNOS) compounds), as verified via isotopic fine structures. These residue-related organosulfur compounds are different to the ones formed during S ion irradiation of ices at 10K. Furthermore, insoluble, apolar material was formed during the sulfur irradiation of residues. Potential organosulfur precursors (CHNO molecules) were identified by means of chemical network analysis. The finding of organosulfur compounds formed by sulfur irradiation of organic residues sheds new light into the rich and complex pristine organosulfur chemistry in the Solar System, as discussed here in context of current and future space missions. These results indicate that space weathering of Solar System bodies may lead to the formation of organosulfur compounds.
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