Suchergebnisse

Context. Many C-, O-, and H-containing complex organic molecules (COMs) have been observed in the interstellar medium (ISM) and their formation has been investigated in laboratory experiments. An increasing number of recent detections of large N-bearing COMs motivates our experimental investigation of their chemical origin. Aims. We investigate the potential role of acetonitrile (CH3CN) as a parent molecule to N-bearing COMs, motivated by its omnipresence in the ISM and structural similarity to another well-known precursor species, CH3OH. The aim of the present work is to characterize the chemical complexity that can result from vacuum UV photolysis of a pure CH3CN ice and a more realistic mixture of H2O:CH3CN. Methods. The CH3CN ice and H2O:CH3CN ice mixtures were UV irradiated at 20 K. Laser desorption post ionization time-of-flight mass spectrometry was used to detect the newly formed COMs in situ. We examined the role of water in the chemistry of interstellar ices through an analysis of two different ratios of H2O:CH3CN (1:1 and 20:1). Results. We find that CH3CN is an excellent precursor to the formation of larger nitrogen-containing COMs, including CH3CH2CN, NCCN/CNCN, and NCCH2CH2CN. During the UV photolysis of H2O:CH3CN ice, the water derivatives play a key role in the formation of molecules with functional groups of: imines, amines, amides, large nitriles, carboxylic acids, and alcohols. We discuss possible formation pathways for molecules recently detected in the ISM. © ESO 2021. ; Acknowledgements. M.B. and H.L. acknowledge the European Union (EU) and Horizon 2020 funding awarded under the Marie Skłodowska-Curie action to the EUROPAH consortium (grant number 722346) as well as NOVA 5 funding. Additional funding has been realized through a NWO-VICI grant. This work has been supported by the Danish National Research Foundation through the Center of Excellence "InterCat" (Grant agreement no.: DNRF150). We thank N. F. W. Ligterink, A. G. G. M. Tielens, J. Terwischa van Scheltinga, J. Bouwman and T. ...

The detection of the amino acid glycine and its amine precursor methylamine on the comet 67P/Churyumov-Gerasimenko by the Rosetta mission provides strong evidence for a cosmic origin of amino acids on Earth. How and when such molecules form along the process of star formation remains debated. Here we report the laboratory detection of glycine formed in the solid phase through atom and radical–radical addition surface reactions under dark interstellar cloud conditions. Our experiments, supported by astrochemical models, suggest that glycine forms without the need for 'energetic' irradiation (such as ultraviolet photons and cosmic rays) in interstellar water-rich ices, where it remains preserved, during a much earlier star-formation stage than previously assumed. We also confirm that solid methylamine is an important side-reaction product. A prestellar formation of glycine on ice grains provides the basis for a complex and ubiquitous prebiotic chemistry in space enriching the chemical content of planet-forming material. © 2020, The Author(s), under exclusive licence to Springer Nature Limited. ; We thank T. Lamberts and I. Jiménez-Serra for stimulating discussions. This research was funded through a VICI grant of the NWO (the Netherlands Organization for Scientific Research) and A-ERC grant number 291141 (CHEMPLAN). Financial support from the Danish National Research Foundation through the Center of Excellence 'InterCat' (Grant agreement no. DNRF150) and from NOVA (the Netherlands Research School for Astronomy) and the Royal Netherlands Academy of Arts and Sciences (KNAW) through a professor prize is acknowledged. S.I. acknowledges the Royal Society for financial support through the University Research Fellowship (grant number UF130409), the University Research Fellowship Renewal 2019 (grant number URF\R\191018), the Research Fellows Enhancement Award (grant number RGF\EA\180306) and the Holland Research School for Molecular Chemistry (HRSMC) for a travel grant. G.F. acknowledges financial support from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie actions grant agreement number 664931 and support from an 'iALMA' grant (CUP C52I13000140001) approved by MIUR (Ministero dell'Istruzione, dell'Universitá e della Ricerca). A.R.C. and R.T.G. thank the NASA Astrophysics Research and Analysis Research programme for funding through grant number NNX15AG07G. V.K. was funded by the NWO PEPSci (Planetary and ExoPlanetary Science) programme. This work benefited from collaborations within the framework of the FP7 ITN LASSIE consortium (grant number GA238258).