Phase Transition of Interstellar CO Ice

Among the over 200 molecular species identified in interstellar clouds, many are organic molecules. It has been proposed that some of these molecules survive star and planet formation process eventually delivered to Earth where they can form basis origin life. is now well established one most important factories ice mantles cover dust grains star-forming clouds. Simple atoms such as H, O, N, CO condense from gas phase onto grain surface then react with each other increasingly complex At extremely low temperature (10–15 K) widely accepted mechanism bring reactive together—diffusion—is severely impeded ice, raising question their formation. In laboratory experiments we find top layers mantle, which made primarily CO, transform a disordered polycrystalline at temperature. During transition, buried inside may migrate without need overcome activation energy for diffusion. By quantifying kinetics crystallization, predict clouds mostly form. The reorganization occurs below 10 K, promote mobility species, therefore be driving force complexity