Infrared Spectroscopic Study on Swift-Ion Irradiation of Solid N 2 O-H 2 O Samples: Synthesis of N-O Bearing Species in Astrophysical Ices.

As of early 2022, only six species bearing an N-O bond have been detected toward cold molecular clouds and regions of star formation. It is not clear yet if the small number of N-O bond species found in the interstellar medium so far stems from physical and technological limitations of astronomical detection techniques, or whether in fact molecules that bear an N-O bond are for some reason rare in these objects of the interstellar medium. Astronomical N-O bearing molecules are important because they are part of astrochemical models which propose that they are precursors of hydroxylamine (NH ₂ OH), a species linked to the formation of prebiotic amino acids in space. The aim of this study is the better understanding of the open question of the interstellar synthesis of N-O bearing species. We have analyzed by infrared spectroscopy an astrophysically relevant polar ice mixture of N ₂ O:H ₂ O processed by 90 MeV ¹³⁶ Xe ²³⁺ ions, which can mimic the physicochemical processes triggered by cosmic rays in water-covered interstellar ice grains. The results show the formation of N ₂ O ₃ and of H ₂ O ₂ , but no HN-O species of any kind were detected. Such findings are discussed in light of recent studies from our group and from the literature.