Hydrogenation of accreting C-atoms and CO molecules -- simulating ketene and acetaldehyde formation under dark and translucent cloud conditions

Abstract

Simple and complex organic molecules (COMs) are observed along different phases of star and planet formation and have been successfully identified in prestellar environments such as dark and translucent clouds. Yet the picture of organic molecule formation at those earliest stages of star formation is not complete and an important reason is the lack of specific laboratory experiments that simulate carbon atom addition reactions on icy surfaces of interstellar grains. Here we present experiments in which CO molecules as well as C- and H-atoms are co-deposited with H${}_2$O molecules on a 10 K surface mimicking the ongoing formation of an "H${}_2$O-rich" ice mantle. To simulate the effect of impacting C-atoms and resulting surface reactions with ice components, a specialized C-atom beam source is used, implemented on SURFRESIDE${}^3$, an UHV cryogenic setup. Formation of ketene (CH${}_2$CO) in the solid state is observed "in situ" by means of reflection absorption IR spectroscopy. C${}^1$${}^8$O and D isotope labelled experiments are performed to further validate the formation of ketene. Data analysis supports that CH${}_2$CO is formed through C-atom addition to a CO-molecule, followed by successive hydrogenation transferring the formed :CCO into ketene. Efficient formation of ketene is in line with the absence of an activation barrier in C+CO reaction reported in the literature. We also discuss and provide experimental evidence for the formation of acetaldehyde (CH${}_3$CHO) and possible formation of ethanol (CH${}_3$CH${}_2$OH), two COM derivatives of CH${}_2$CO hydrogenation. The underlying reaction network is presented and the astrochemical implications of the derived pathways are discussed.

Accepted by ApJ

References in corpus (21)

• Formation of Complex Molecules in Prestellar Cores: a Multilayer Approach
• Experimental evidence for Glycolaldehyde and Ethylene Glycol formation by surface hydrogenation of CO molecules under dense molecular cloud conditions
• Atom addition reactions in interstellar ice analogues
• Water in star-forming regions (WISH): Physics and chemistry from clouds to disks as probed by Herschel spectroscopy
• Formation of Complex Organic Molecules in Cold Interstellar Environments through non-diffusive grain-surface and ice-mantle chemistry
• A non-energetic mechanism for glycine formation in the interstellar medium
• Spatial mapping of ices in the Oph-F core: A direct measurement of CO depletion and the formation of CO2
• Formation of Glycerol through Hydrogenation of CO ice under Prestellar Core Conditions
• H-atom bombardment of CO2, HCOOH and CH3CHO containing ices
• An experimental study of the surface formation of methane in interstellar molecular clouds
• Production of complex organic molecules: H-atom addition versus UV irradiation
• Formation of COMs through CO hydrogenation on interstellar grains
• Chemical Variation among Protostellar Cores: Dependence on Prestellar Core Conditions
• Carbon Atom Reactivity with Amorphous Solid Water: H${}_2$O Catalyzed Formation of H${}_2$CO
• The Case of H${}_2$C${}_3$O Isomers, Revisited: Solving the Mystery of the Missing Propadienone
• Oxygen atom reactions with C2H6, C2H4, and C2H2 in ices
• Formation of complex organic molecules in molecular clouds: acetaldehyde, vinyl alcohol, ketene, and ethanol via the "energetic" processing of C${}_2$H${}_2$ ice
• Formation of Acetaldehyde on CO-rich Ices
• Experimental Characterization of the Energetics of Low-temperature Surface Reactions
• A cryogenic ice setup to simulate carbon atom reactions in interstellar ices
• Alcohols on the rocks: solid-state formation in a H3CCCH + OH cocktail under dark cloud conditions

Cited by in corpus (21)

• Laboratory and Computational Studies of Interstellar Ices
• CoCCoA: Complex Chemistry in hot Cores with ALMA. Selected oxygen-bearing species
• JOYS+: link between ice and gas of complex organic molecules. Comparing JWST and ALMA data of two low-mass protostars
• Surface Diffusion of Carbon Atoms as a Driver of Interstellar Organic Chemistry
• Formation of complex organic molecules on interstellar CO ices? Insights from computational chemistry simulations
• Acetaldehyde binding energies: a coupled experimental and theoretical study
• Discovery of thionylimide, HNSO, in space: the first N-, S- and O-bearing interstellar molecule
• Methane formation in cold regions from carbon atoms and molecular hydrogen
• Enhanced formation of interstellar complex organic molecules on carbon monoxide ice
• A deep search for large complex organic species toward IRAS16293-2422 B at 3 mm with ALMA
• Correlations of Methyl Formate (CH3OCHO), Dimethyl Ether (CH3OCH3) and Ketene (H2CCO) in High-mass Star-forming Regions
• Millimetre and sub-millimetre spectroscopy of doubly deuterated acetaldehyde (CHD2CHO) and first detection towards IRAS 16293-2422
• CoCCoA: Complex Chemistry in hot Cores with ALMA. The chemical evolution of acetone from ice to gas
• Carbon Isotope Fractionation of Complex Organic Molecules in Star-Forming Cores
• Hydrogenation of acetaldehyde on interstellar ice analogs reveals limited destruction
• Complex Organic Molecules towards the central molecular zone of NGC 253
• Journey of complex organic molecules: Formation and transport in protoplanetary disks
• In situ characterization of volatile and refractory hydrocarbons produced by UV photolysis of interstellar C${}_2$H${}_2$ ice
• Isotopomer-Specific Carbon Isotope Ratio of Complex Organic Molecules in Star-Forming Cores
• Spatial distribution of organics in the Horsehead nebula: Signposts of chemistry driven by atomic carbon
• The Reaction between Atomic Carbon and Molecular Nitrogen as a Source of Cyanamide and Carbodiimide on Interstellar Ices