arXiv subjects

Alicja Domaracka

Publications and source records attributed to Alicja Domaracka.

4 recordsLinked to original sources

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↗

arXiv2025

Isomer effects on neutral-loss dissociation channels of nitrogen-substituted PAH dications

We investigate two nitrogen-containing isomers of polycyclic aromatic hydrocarbons (PAHs), quinoline (Q) and isoquinoline (IQ), of composition C$_9$H$_7$N in collisions with 7~keV O$^+$ and 48~keV O$^{6+}$ projectile ions. Employing ion-ion coincidence mass spectrometry, we determine branching ratios for H-loss, C$_2$H$_2$-loss, and HCN-loss dissociation channels of Q$^{2+}$ and IQ$^{2+}$. The overall contribution of HCN-loss is found to be the dominant decay channel. A comparison with the results of a parallel experiment on naphthalene, the simplest PAH, reveals that HCN-loss in both isomers has a higher propensity than the analogous C$_2$H$_2$-loss of naphthalene. The positional identity of the nitrogen atom in the two isomers mainly manifests in many-body fragmentation of their dications. Potential energy surfaces of Q$^{2+}$ and IQ$^{2+}$ are further computed to explore complete fragmentation mechanisms. Parent dications (Q$^{2+}$ and IQ$^{2+}$) are identified to isomerize via seven-membered ring structures prior to elimination of C$_2$H$_2$ and HCN. While prompt dissociation is the primary pathway, the dominant channel of each neutral-loss class also exhibits delayed fragmentation.

physics.chem-ph↗

arXiv2024

Bond breaking and making in mixed clusters of fullerene and coronene molecules following keV-ion impact

We have performed classical molecular dynamics simulations of 3 keV Ar + $(\mathrm{C}_{24}\mathrm{H}_{12})_n(\mathrm{C}_{60})_{m}$ collisions where $(n,m)=(3,2), (1,4), (9,4)$ and $(2,11)$. The simulated mass spectra of covalently bound reaction products reproduce the main features of the corresponding experimental results reported by Domaracka et al., PCCP, 2018, 20, 15052. The present results support their conclusion that molecular growth is mainly driven by knockout where individual atoms are promptly removed in Rutherford type scattering processes. The so formed highly reactive fragments may then bind with neighboring molecules in the clusters producing a rich variety of growth products extending up to sizes containing several hundreds of atoms, and here we show examples of such structures. In addition, knocked out atoms may be absorbed such that e.g. hydrogenated coronene and fullerene molecules are formed.

physics.chem-ph↗

arXiv2017

Ion-Induced Molecular Growth in Clusters of Small Hydrocarbon Chains

We report on studies of collisions between 3 keV Ar$^+$ projectile ions and neutral targets of isolated 1,3-butadiene (C$_4$H$_6$) molecules and cold, loosely bound clusters of these molecules. We identify molecular growth processes within the molecular clusters that appears to be driven by knockout processes and that could result in the formation of (aromatic) ring structures. These types of reactions are not unique to specific projectile ions and target molecules, but will occur whenever atoms or ions with suitable masses and kinetic energies collide with aggregates of matter, such as carbonaceous grains in the interstellar medium or aerosol nanoparticles in the atmosphere.

physics.atm-clus↗