Low-temperature Condensation of Carbon

Abstract

Two different types of experiments were performed. In the first experiment we studied the low-temperature condensation of vaporized graphite inside bulk liquid helium while in the second experiment the condensation of single carbon atoms together with H2, H2O, and CO molecules inside helium nanodroplets was studied. The condensation of vaporized graphite leads to the formation of partially graphitized carbon, which indicates high-temperatures, supposedly higher than 1000 °C, during the condensation. Possible underlying processes responsible for the instant rise in temperature during condensation are discussed. This suggests that such processes cause the presence of partially graphitized carbon dust formed by low-temperatures condensation in the diffuse interstellar medium. Alternatively, in the denser regions of the ISM, the condensation of carbon atoms together with the most abundant interstellar molecules (H2, H2O, and CO), leads to the formation of complex organic molecules (COMs) and finally organic polymers.Water molecules were found not to be involved directly in the reaction network leading to the formation of COMs. It was proposed that COMs are formed via addition of carbon atoms to H2 and CO molecules (C + H2 → HCH, HCH + CO → OCCH2). Due to the involvement of molecular hydrogen, the formation of COMs by carbon addition reactions should be more efficient at high extinctions compared with the previously proposed reaction scheme with atomic hydrogen.

Separate Silicate and Carbonaceous Solids Formed from Mixed Atomic and Molecular Species Diffusing in Neon Ice

“…More recently, experiments by our group have demonstrated the formation of complex silicates (Rouillé et al 2014a) and of carbonaceous solid matter (Fulvio et al 2017) at temperatures not higher than 13 and 15 K, respectively. In liquid helium, at 1.7 K, carbon atoms and molecules were found to condense into a partially graphitized solid (Krasnokutski et al 2017). In such conditions, a chemistry that requires very little activation energy, if any, is involved (Krasnokutski et al 2014).…”

Formation pathways of proteins in space

“…Therefore, a notable portion of carbonaceous dust is expected to be formed by the accretion of C atoms. This leads to the formation of organics 28 . As revealed by the current study, a notable portion of this organics could be in the form of peptides.…”

Adsorption of Organic Molecules on Onion-like Carbons: Insights on the Formation of Interstellar Hydrocarbons

“…The presence of PAHs and carbon nanoparticles has been invoked to explain the atmospheric composition of exoplanets such as the warm Jupiter HD 189733b (Mousis et al 2011). Moreover, analysis on Allende meteorites by laser desorption mass spectrometry (LDMS) and microscopy experiments has shown onion-like structures of higher fullerenes (Rotundi et al 1998;Becker et al 1999;Jäger et al 2006;Krasnokutski et al 2017). The presence of grain layered carbon nanostructures in the ISM has therefore been unambiguously proposed in many studies (Chiar et al 2013;Shi et al 2015;Anderson et al 2017).…”