Navegando por Autor "Boduch, Philippe"

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    Influence of temperature on the chemical evolution and desorption of pure CO ices irradiated by cosmic-rays analogues
    (Royal Astronomical Society) Pilling, Sergio; Mateus, Marcelo Silva; Ojeda González, Arian; Ferrão, Luiz Fernando de Araujo; Galvão, Breno R. L.; Boduch, Philippe; Rothard, Hermann
    Carbon monoxide (CO) plays a vital role in interstellar chemistry, existing abundantly in both gaseous and frozen environments. Understanding the radiation-driven chemistry of CO-rich ices is crucial for comprehending the formation and desorption of C-bearing molecules in the interstellar medium (ISM), particularly considering the potential impact of temperature on these processes. We report experimental data on irradiation processing of pure CO ice by cosmic ray analogues (95.2 MeV 136Xe23+ ions) at temperatures of 10, 15, and 20 K, in the IGLIAS set-up coupled to the IRRSUD beamline at GANIL (Caen, France). The evolution of the irradiated frozen samples was monitored by infrared spectroscopy. The computational PROCODA code allows us to quantify the chemical evolution of the samples, determining effective reaction rates coefficients (ERCs), molecular abundances at the chemical equilibrium (CE) phase, and desorption processes. The model integrated 18 chemical species – 8 observed (CO, CO2, C3, O3, C2O, C3O, C3O2, and C5O3) and 10 non-observed but predicted (C, O, C2, O2, CO3, C4O, C5O, C2O2, C2O3, C4O2) – linked via 156 reactions. Our findings reveal temperature-driven influences on molecular abundances at chemical equilibrium, desorption yields and rates, and ERC values. Certain reaction routes exhibit distinct thermochemical behaviours of gas- and ice-phase reactions which may be attributed to the presence of neighbouring molecules within the ice matrix. This study provides pivotal insights into the chemical evolution of CO-enriched ice under irradiation, impacting solid-state astrochemistry, clarifying molecular abundances, and advancing our understanding of ISM chemistry and temperature effects on ionized radiation-processed frozen ices.
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    Methylenimine and cyanomethanimine synthesis from ion irradiation of N2-CH4 ice: Implication on the formation of prebiotic molecules in outer solar system bodies
    (Elsevier) Vasconcelos, Fredson de Araujo; Pilling, Sergio; Agnihotri, Aditya Narain; Rothard, Hermann; Boduch, Philippe
    The synthesis of methylenimine and cyanomethanimine from ion irradiation of N2-CH4 ice was studied, in an attempt to simulate the role of medium mass cosmic rays and energetic solar particles in the processing of nitrogen-rich ices on cold astrophysical environments, such as those in the outer region of the solar system (e.g. Pluto, Charon, Triton, Makemake and Titan). The N2-CH4 (90:10) ice mixture was irradiated at 9 K by 38.4 MeV 40Ca9+ (0.96 MeV/u) at the GANIL facility (Caen/Fance). The evolution of the samples was monitored using in-situ Fourier transform infrared spectroscopy (FTIR). The results indicate the formation of CH2NH and CH2NCN, which are considered species of interest in prebiotic chemistry. Other species produced by radiolysis were HCN, HNC, hydrocarbons and nitriles. Direct comparison of the laboratory spectrum from the mixture of reaction products provides an efficient way to focus on the identification of chemical synthesis routes for the production of molecules important in the development of life that are consistent with the chemical inventory and physical conditions on frozen moons and cold objects in the outer solar system.