20-EPN2-070: Formation of Glycine and Alanine upon ion irradiation of space relevant ices
Visit by Alejandra Traspas Muina, Queen Mary University of London (UK), to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 20 March – 2 April 2023
Report Summary: The experiments initially proposed aimed to investigate the formation and chemical evolution of both glycine and alanine under space relevant conditions. Following a systematic approach, the TA was divided into three projects carried out by a multidisciplinary group of scientist (chemists, biologists, astrophysicists and engineers): looking at (i) experimental insights into the microphysics of molecule destruction and sputtering of CO2 exposed to cosmic rays analogues; (ii) the formation of methyl formate and its isomers (glycolaldehyde and acetic acid) through the systematic irradiation of H2 CO:CO, H2 CO:CH4 , and H2 CO:CH3 OH ice mixtures with 1 MeV and 200 keV H+ ; (iii) and 1 MeV H+ irradiation of pure Glycine and Glycine:CH4 interstellar relevant ice mixtures, exploring the survivability and stability of this amino acid in astrophysical relevant environments.
The three projects were designed with incremental molecular complexity to investigate the chemistry of many precursors of simple amino acids. Moreover, the sub-projects were designed to be connected to other awarded TAs either at ICA or AQUILA (PIs: Ivlev, Ioppolo, and Hopkinson) in a synergic manner. For instance, the work of H2 CO completes the systematic study on methyl formate and its isomers, started at this Europlanet facility 2 years ago, trying to improve the understanding of the standing dichotomy on the formation of glycolaldehyde, methyl formate, and acetic acid. All these species are detected in space in star-forming regions and are considered prebiotic molecules.
Full scientific report published by kind permission of Alejandra Traspas Muina
20-EPN-049: The Irradiation of Oxygen-Bearing Ices on Top of Pure Elemental Sulphur Layers (former title: Millimetre-Wave Polarimetry of Space Relevant Ices Exposed to Energetic Ions)
Virtual visit by Olivier Auriacombe, Chalmers University of Technology (Sweden), to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 20 June – 4 September 2022
Report Summary: The chemistry of sulphur in icy extra-terrestrial settings such as the dense interstellar medium and the outer Solar System remains poorly constrained. In particular, the chemical routes towards the formation of SO2 ice (and other volatile sulphur-bearing species) is not completely understood, despite the detection of this species in interstellar icy grain mantles, on the surface of Europa, and on comets. We have therefore explored the possibility of forming SO2 ice as a result of the irradiation of oxygen-bearing ices (including O2, CO, CO2, H2O, and CH3OH) deposited on top of pure elemental sulphur layers, both of which are known to exist in the dense interstellar medium and the outer Solar System where radiation chemistry may be engendered by galactic cosmic rays or the solar wind.
Our results demonstrate that SO2 may indeed be produced after the 1 MeV He+ ion irradiation of O2 and CO2 ices deposited on top of elemental sulphur, but not as a result of similar irradiations conducted using CO, H2O, or CH3OH ices. Other volatile radiation product species incorporating sulphur, such as CS2, OCS, and H2SO4, were also detected in different experiments. Our work should therefore contribute to a better understanding of solid-phase sulphur astrochemistry and the role of elemental sulphur in the formation of volatile sulphur-bearing species in icy extra-terrestrial settings.
20-EPN2-045: Irradiation Effects of Energetic H+ and S+ Ion Implantation in Salts and Minerals Relevant to the Surface of Europa
Virtual visit by Duncan Mifsud, University of Kent (UK) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 21-29 November 2022 and 18-20 January 2023
Report Summary: The surface of Europa is host to a rich radiation environment, in which ions from the giant Jovian magnetosphere drive physico-chemical transformations of surface ices and minerals. Although a number of previous studies have looked into the irradiation of surface ice analogues in order to better constrain the chemistry occurring on Europa, considerably fewer studies have investigated the radiation chemistry of plausible mineral analogues.
Therefore, in this study, we have irradiated four mineral species (halite, fayalite, epsomite, and berthierine) using 1 MeV H+ and 1 MeV S+ ions to better understand the dissociation pathways of these minerals and the associated radiolysis products. Our preliminary results have shown that irradiation brings about significant changes in the appearances of the minerals that signify alterations in the structures and chemical compositions. Further infrared, visible, and ultraviolet spectroscopic analyses of retained mineral samples (both irradiated and pristine) are planned for the near future.
20-EPN-025: Radioresistance of aromatic complex organic molecules (nucleobases)
Virtual visit by Alicja Domaracka and Anna Bychkova, CIMAP-CNRS (France) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 17-28 January 2022
Report Summary: Over the last decades it became clear that we live in a “molecular universe”. Carbon forms the basis of the majority of the molecular species that so far have been identified in space. Although small carbon-based molecules, like CO and CO2, are some of the most abundant molecules in space, only a small fraction of the carbon is expected to be locked up in such species. It was proposed that a large portion of the interstellar carbon, up to 20%, is built in polycyclic aromatic hydrocarbons (PAHs) and fullerenes. Several laboratory studies were carried out to investigate the effects of vacuum ultraviolet photolysis on PAH:H2O ices. However, data about interaction energetic ions with PAH ices are very scare.
We therefore studied the radiolysis of the pure pyrene ice and mixed pyrene- water ices at different concentrations at 20 K with 200 keV and 2 MeV H+ and 2 MeV C2+ beams at Atomki. The preliminary analysis of water-pyrene ices irradiated 200 keV H+ (with pyrene concentration from about 5 to 100% of pyrene) indicates that pyrene is more radio-resistant at high concentrations. The results are preliminary and analysis is ongoing.
20-EPN-084: Converting one amino acid to the other containing sulfur via ion irradiation : Implication to chemical evolution on Europa surface ices
Visit by Rahul Kumar Kushwaha, Physical Research Laboratory, Ahmedabad (India) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 8-19 December 2021
Report Summary: The non-equilibrium chemistry driven by the charged particle and photon irradiation processes are responsible for the rich chemistry on the surfaces of icy satellites. Among the icy satellites of the Jovian and Saturnian planetary systems, a few satellites such as Ganymede, Europa, Dione, Rhea, Callisto and Titan that are embedded in their respective planetary magnetospheres were observed to undergo rich chemical processes due to the bombardment of a wide range of energetic atomic and molecular ions that are present in their planet’s magnetospheres, which processes the icy surfaces of satellites by irradiation and implantation. Magnetospheres also help in bringing new species from one satellite to the other. Especially in the Jupiter system of icy satellites, sulfur transfer from Io to the other satellites is quite likely. The sulfur ions from Io are picked up by the magnetosphere and are accelerated towards the other icy satellites; Europa being the closest neighbour to Io will be implanted with sulfur ions. The Jovian satellites, due to the presence of the Jupiter’s magnetosphere, are subjected to highly energetic S ion irradiation which leads to a range of chemical activity on their surfaces. In this project, we have studied the effect of S ion irradiation on Aspartic acid for a range of energies at two different temperatures (100 K, 20 K), where the 100 K experiments are aimed to mimic the conditions of Europa. The irradiated residue was then analysed using an optical microscope, scanning electron microscope and liquid chromatography mass spectrometry.
Full scientific report published by kind permission of Rahul Kumar Kushwaha
20-EPN-016: Formation and fate of methyl formate isomers in space
Virtual visit by Dr Sergio Ioppolo (Queen Mary University of London, UK) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 12 October 2020 – 31 March 2021
Report Summary: All isomers of C2H4O2, i.e. glycolaldehyde (HCOCH2OH), acetic acid (CH3COOH) and methyl formate (HCOOCH3), have been observed abundantly around the Galactic center, in dark clouds, and hot cores of the interstellar medium (ISM), as well as in some minor ice objects of the Solar System. However, their exact gas-grain formation and destruction pathway is still under debate. According to El-Abd et al. (2019), the observed column densities of methyl formate and acetic acid are well-correlated, and are likely simply tracking the relative total gas mass in star forming regions. Methyl formate and glycolaldehyde, however, display a stark dichotomy in their relative column densities. The latter findingsuggests that different formation/destruction routes are at play for the three isomers. To date, there is a strong laboratory evidence for an efficient production of glycolaldehyde, methyl formate, and acetic acid in the ISM (Gerakines et al. 1996; Bennett and Kaiser 2007; Modica et al. 2012).
During the TA 20-EPN-016 at the ion accelerator facility Atomki in Debrecen (Hungary), we have performed a systematic set of experiments using the novel ultrahigh vacuum ICA end station to investigate the formation and destruction pathways of C2H4O2 isomers and a variety of other interstellar complex organic molecules. The experimental campaign revealed to be successful as all the planned experiments were performed. Results aided the design of new potential key experiments that will be included in a future follow-up beamtime bid at the facility.
20-EPN-005: Cosmic-ray-induced chemistry in pure ices
Virtual visit by Alexei Ivlev, Max Planck Institute for Extraterrestrial Physics (MPE) (Germany) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 23 February – 05 July 2021
Report Summary: The principal aim of the project was a dedicated study of generic effects induced in pure astrophysical ice analogs due to their bombardment by cosmic rays with energies E in the vicinity of the maximum of electronic stopping power. It is known that the energy of ejected electrons, which are produced in primary ionization events, has a significant dependence on E in this energy range.
Thus, by selecting pairs of beam energies on both sides of the Bragg peak, such that the corresponding stopping-power values are equal, we were able to probe the effect of electron-impact excitations of ice molecules. We selected CO films as the best irradiation target, for which the biggest variety of radiolysis products was expected and the most detailed predictions of chemical models were available.
We found that the first radiolysis products, detected at the astrophysically relevant values of ion fluence, are very different from predictions of chemical models. At the same time, the reaction kinetics shows no statistically significant difference between ion beams of same stopping power. This rules out the importance of electron-impact excitation in radiolysis chemistry of CO, and suggests that this process may generally be negligible compared to the chemistry driven by CR heating (determined by the stopping power value). On the other hand, by comparing the sputtering yields measured for beams of same stopping power, we discovered a significant asymmetry, with the yield at lower energies being up to a factor of two larger that at higher energies.
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20-EPN-043: A Systematic Study of Sulfur Ion Radiolysis of Simple Oxide Ices.
Visit by Zuzana Kanuchova (virtual participation), Astronomical Institute od Slovak Academy of Sciences (Slovakia) and Duncan Mifsud (in-person participation), University of Kent (UK) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 30 November – 4 December 2020 and 25-29 January 2021
Report Summary: We have implanted 290 keV S+ ions in a variety of simple oxide ices, including CO, CO2, H2O, N2O, O2, and CO:N2O at 20 K, as well as CO2 and H2O at 70 K. Our aim was to determine whether such implantations could result in the formation of sulfur-bearing product molecules, particularly SO2 which has been detected at the surfaces of several icy Solar System moons.
The performed experiments suffered from initial setbacks in the form of unexpected and significant sputtering of the astrophysical ice analogues during irradiation. In order to mitigate this sputtering, we made use of two different experimental techinques; (i) via simultaneous deposition and irradiation of the ice analogue in cases where we knew gas phase chemistry to be negligible, and (ii) via creation of a very thick (~3-5 μm) ice and a slow rate of implantation. Once these initial problems were solved, we were able to successfully carry out implantations into the six ices mentioned above.
Our work has indicated that although sulfur-bearing molecules (such as OCS and H2SO4 hydrates) may form as a result of such implantations, SO2 formation was not detected in most experiments, except at high fluence (~1016 ions/cm2) implantations in CO. Such results have important implications for the icy Galilean satellites of Jupiter, suggesting that the SO2 present there may be formed by endogenic processes at the lunar surfaces.
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20-EPN-032: Radioresistance of aromatic complex organic molecules: nucleobases.
Virtual visit by Hermann Rothard, CIMAP (Caen, F) CNRS (France) to TA2.11 Atomki Ice Chamber for Astrophysics / Astrochemistry (ICA) (Hungary).
Dates of visit: 17 May – 02 July 2021
Report Summary: Complex molecules (including amino acids and nucleobases) can be formed in cold space environments conditions (e.g. dense molecular clouds, outer solar system) by e.g. UV irradiation and ion bombardment of ices containing simple molecules. Consequently, the radiation resistance of such complex molecules in order to determine their survival times in space should be investigated. We therefore studied the radiolysis and radio-resistance of the purine nucleobase (Adenine, two aromatic rings) in solid phase as a function of temperature (20-300 K) with H (0.8 MeV) and He (3.2 MeV) beams at ATOMKI. This first systematic study of the influence of the temperature revealed that Adenine is found to be significantly (of the order of 50%) more radio-resistant at high temperatures. At low temperatures T < 50K, Adenine is more radiosensitive (higher cross sections).
The results are preliminary and analysis is ongoing. Furthermore, we found that the destruction cross sections scales with the electronic stopping stopping following a power law with a stronger than linear dependence.
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