Dust Motions in Magnetized Turbulence: Source of Chemical Complexity
  Notwithstanding manufacture of complex organic molecules from impacting
cometary and icy planet surface analogues is well-established, dust grain-grain
collisions driven by turbulence in interstellar or circumstellar regions may
represent a parallel chemical route toward the shock synthesis of prebiotically
relevant species. Here we report on a study, based on the multi-scale
shock-compression technique combined with ab initio molecular dynamics
approaches, where the shock-waves-driven chemistry of mutually colliding
isocyanic acid (HNCO) containing icy grains has been simulated by
first-principles. At the shock wave velocity threshold triggering the chemical
transformation of the sample (7 km/s), formamide is the first synthesized
species representing thus the spring-board for the further complexification of
the system. In addition, upon increasing the shock impact velocity, formamide
is formed in progressively larger amounts. More interestingly, at the highest
velocity considered (10 km/s), impacts drive the production of diverse
carbon-carbon bonded species. In addition to glycine, the building block of
alanine (i.e., ethanimine) and one of the major components of a plethora of
amino-acids including, e.g., asparagine, cysteine, and leucine (i.e.,
vinylamine) have been detected after shock compression of samples containing
the most widespread molecule in the universe (H2) and the simplest compound
bearing all the primary biogenic elements (HNCO). The present results indicate
novel chemical pathways toward the chemical complexity typical of interstellar
and circumstellar regions.
