Comparison of UV and high-energy ion irradiation of methanol:ammonia ice

Abstract

The main goal of this work is to compare the effects induced in ices of astrophysical relevance by high-energy ions, simulating cosmic rays, and by vacuum ultraviolet (UV) photons. This comparison relies on in situ infrared spectroscopy of irradiated CH3OH:NH3 ice. Swift heavy ions were provided by the GANIL accelerator. The source of UV was a microwave-stimulated hydrogen flow discharge lamp. The deposited energy doses were similar for ion beams and UV photons to allow a direct comparison. A variety of organic species was detected during irradiation and later during ice warm-up. These products are common to ion and UV irradiation for doses up to a few tens of eV per molecule. Only the relative abundance of the CO product, after ice irradiation, was clearly higher in the ion irradiation experiments. For some ice mixture compositions, the irradiation products formed depend only weakly on the type of irradiation, swift heavy ions, or UV photons. This simplifies the chemical modeling of energetic ice processing in space.

9 pages, 9 figures, 2 tables, accepted in A&A

References in corpus (2)

• Vacuum-UV spectroscopy of interstellar ice analogs. I. Absorption cross-sections of polar-ice molecules
• Vacuum-UV spectroscopy of interstellar ice analogs. II. Absorption cross-sections of nonpolar ice molecules

Cited by in corpus (17)

• Photochemistry and astrochemistry: photochemical pathways to interstellar complex organic molecules
• Formation of Complex Molecules in Prestellar Cores: a Multilayer Approach
• Astrochemistry of dust, ice and gas: introduction and overview
• The formation of peptide-like molecules on interstellar dust grains
• Formation of NH2CHO and CH3CHO upon UV photoprocessing of interstellar ice analogs
• Laboratory Studies of Methane and Its Relationship to Prebiotic Chemistry
• The efficiency of photodissociation for molecules in interstellar ices
• Synthesis of complex organic molecules in soft x-ray irradiated ices
• Infrared spectra of complex organic molecules in astronomically relevant ice matrices. III. Methyl formate and its tentative solid-state detection
• Irradiation dose affects the composition of organic refractory materials in space: Results from laboratory analogues
• Enhanced formation of interstellar complex organic molecules on carbon monoxide ice
• The rapid formation of macromolecules in irradiated ice of protoplanetary disk dust traps
• Ionization of Ammonia Nanoices With Adsorbed Methanol Molecules
• Photochemistry of interstellar ice forming Complex Organic Molecules
• First observations of warm and cold methanol in Class 0/I proto-brown dwarfs
• Exploring refractory organics in extraterrestrial particles
• Amides from the carbonaceous asteroid (162173) Ryugu: nanoscale spectral and isotopic characterizations