Hermann Rothard | Searcharxiv

arXiv2026

Formation of nitriles and isonitriles by the heavy-ion irradiation of propionitrile in N2-rich astrophysical ices

Context. Nitriles are key nitrogen-bearing organic molecules in dense clouds, star-forming regions, and nitrogen-rich icy environments. Understanding their stability and chemical evolution under energetic processing is essential for understanding the formation of complex organic species in astrophysical ices. Aims. We investigate the radiolytic processing of propionitrile (CH3CH2CN, hereafter referred to as PCN) in a nitrogen-rich ice matrix and evaluate the formation of nitriles, isonitriles, hydrocarbons, and other nitrogen-bearing products induced by swift heavy ions. Methods. A PCN:N2 ice mixture with an approximate molecular ratio of 1:10 was deposited at 10 K and irradiated with 40 MeV 40Ar9+ ions up to a fluence of 1 x 1013 ions cm-2. The chemical evolution was monitored in situ by Fourier-transform infrared spectroscopy. Destruction and formation cross sections, as well as radiation chemical yields, were derived from the fluence dependence of selected infrared bands. Results. Ion irradiation efficiently destroys PCN and produces a rich inventory of daughter species. The products include: nitriles and isonitriles such as HCN, HCNN, HC3N, CH3CN, CH3C3N, CH3CHCNH, CH2CHCN, NCCN/C2N2, CN, and C2N; nitrogen-bearing species such as CH2NH, CH3NH2, CH3N3, and N3- ; and hydrocarbons, including CH4, C2H2, C2H4, C2H6, and C4H4. The derived cross sections indicate that CN-bearing fragments and hydrocarbons are among the most efficiently formed products, demonstrating that the CN group is efficiently preserved and that extensive carbon-chain reorganization also occurs. Conclusions. The results demonstrate that the energetic processing of PCN in N2-rich ices provides an efficient pathway to molecular complexity under conditions relevant to dense interstellar clouds, protostellar environments, and nitrogen-rich outer Solar System surfaces.

astro-ph.EP↗

arXiv2014

Radiolysis of Amino Acids by Heavy and Energetic Cosmic Ray Analogs in Simulated Space Environments: $α$-Glycine Zwitterion Form

In this work, we studied the stability of the glycine molecule in the crystalline zwitterion form, known as α-glycine ($^{+}$NH$_{3}$CH$_{2}$COO$^{-}$) under action of heavy cosmic ray analogs. The experiments were conducted in a high vacuum chamber at heavy ions accelerator GANIL, in Caen, France. The samples were bombarded at two temperatures (14 K and 300 K) by $^{58}$Ni$^{11+}$ ions of 46 MeV until the final fluence of $10^{13}$ ions cm$^{-2}$. The chemical evolution of the sample was evaluated in-situ using Fourrier Transformed Infrared (FTIR) spectrometer. The bombardment at 14 K produced several daughter species such as OCN$^-$, CO, CO$_2$, and CN$^-$. The results also suggest the appearing of peptide bonds during irradiation but this must be confirmed by further experiments. The halflives of glycine in Interstellar Medium were estimated to be 7.8 $\times 10^3$ years (300 K) and 2.8 $\times 10^3$ years (14 K). In the Solar System the values were 8.4 $\times 10^2$ years (300 K) and 3.6 $\times 10^3$ years (14 K). It is believed that glycine could be present in space environments that suffered aqueous changes such as the interior of comets, meteorites and planetesimals. This molecule is present in proteins of all alive beings. So, studying its stability in these environments provides further understanding about the role of this specie in the prebiotic chemistry on Earth.

astro-ph.EP↗