Meteorite Impact-Induced Rapid NH₃ Production on Early Earth: Ab Initio Molecular Dynamics Simulation

NH₃ is an essential molecule as a nitrogen source for prebiotic amino acid syntheses such as the Strecker reaction. Previous shock experiments demonstrated that meteorite impacts on ancient oceans would have provided a considerable amount of NH₃ from atmospheric N₂ and oceanic H₂O through reduction by meteoritic iron. However, specific production mechanisms remain unclear, and impact velocities employed in the experiments were substantially lower than typical impact velocities of meteorites on the early Earth. Here, to investigate the issues from the atomistic viewpoint, we performed multi-scale shock technique-based ab initio molecular dynamics simulations. The results revealed a rapid production of NH₃ within several picoseconds after the shock, indicating that shocks with greater impact velocities would provide further increase in the yield of NH₃. Meanwhile, the picosecond-order production makes one expect that the important nitrogen source precursors of amino acids were obtained immediately after the impact. It was also observed that the reduction of N₂ proceeded according to an associative mechanism, rather than a dissociative mechanism as in the Haber-Bosch process.