REACTIONS OF ENERGETIC CARBON AND NITROGEN IN H₂O, NH₃ AND CH₄ ICES AND IMPLICATIONS IN COSMIC CHEMISTRY

Abstract
Atoms or ions with kinetic energies exceeding a few eV are able to undergo unconventional chemical reactions such as endothermic processes and those with high energy of activation, among them atom-molecule reactions. This so-called hot atom chemistry (1) is of importance for the interactions of accelerated particles from solar wind, solar flares, cosmic rays, radiation belts of planets and their satellites, colliding interstellar gas and dust clouds, shock waves, etc... with solids in space, particularly with the icy matter of interplanetary and interstellar dust, comets, meteorite parent bodies, surfaces of icy planets or satellites and planetary rings (2-4). More important than the chemical reactions of the primary projectiles seem to be those of the energetic secondaries, created by knock-on of target atoms (5). These processes may add effectively to the classical thermal or epithermal ion molecule and plasma chemical reactions and the radiolytical, photolytical, and other radial processes studied in cosmic chemistry hitherto. Laboratory simulation is performed by recoil processes after nuclear reactions induced by protons or deuterons from a cyclotron. Hot carbon and nitrogen atoms with kinetic energies of 2 to 3 MeV are created by the ¹⁴N (p,α)¹¹C, ¹⁶O(p,αpn)¹¹C, ¹⁶O(p,α) ¹³N, and ¹²C(d,n)¹³N nuclear reactions in H₂O-ice, frozen NH₃ and CH₄ at 77 K. The newly formed chemical products are detected via the radioactivity of their ¹¹C and ¹³N labels by radio-gas- and -high performance liquid chromatography.