2014/09/19 by L. J. Karssemeijer, H. M. Cuppen · 1 citation
Physics and Astronomy · #astro-ph.GA #physics.chem-ph
paper · pdf · doi:10.1051/0004-6361/201424792
published as A&A 569, A107 (2014) · 4 pages, 3 figures, accepted for publication in Astronomy & Astrophysics
arxiv created 2014/09/19 · arxiv updated 2014/10/01
Diffusion of atoms and molecules is a key process for the chemical evolution in the star forming regions of the interstellar medium. Accurate data on the mobility of many important interstellar species is however often not available and this provides a serious limitation for the reliability of models describing the physical and chemical processes in molecular clouds. Here we aim to provide the astrochemical modeling community with reliable data on the ratio between the energy barriers for diffusion and desorption for adsorbed CO and CO2 on water ices. To this end, we use a fully atomistic, off-lattice kinetic Monte Carlo technique to generate dynamical trajectories of CO and CO2 molecules on the surface of crystalline ice at temperatures relevant for the interstellar medium. The diffusion to desorption barrier ratios are determined to be 0.31 for CO and 0.39 for CO2 . These ratios can be directly used to improve the accuracy of current gas-grain chemical models.