2014/02/13 by M. Minissale, E. Congiu, S. Baouche +7 · 1 citation
Physics and Astronomy · #cond-mat.mtrl-sci #astro-ph.CO #physics.chem-ph #msc:85
paper · pdf · doi:10.1103/physrevlett.111.053201
published as PRL 111, 053201 (2013) · 13 pages, 4 figures
arxiv created 2014/02/13 · arxiv updated 2014/02/14
Any evolving system can change of state via thermal mechanisms (hopping a barrier) or via quantum tunneling. Most of the time, efficient classical mechanisms dominate at high temperatures. This is why an increase of the temperature can initiate the chemistry. We present here an experimental investigation of O-atom diffusion and reactivity on water ice. We explore the 6-25 K temperature range at sub-monolayer surface coverages. We derive the diffusion temperature law and observe the transition from quantum to classical diffusion. Despite of the high mass of O, quantum tunneling is efficient even at 6 K. As a consequence, the solid-state astrochemistry of cold regions should be reconsidered and should include the possibility of forming larger organic molecules than previously expected.