Diffusion in binary gas mixtures studied by NMR of hyperpolarized gases and molecular dynamics simulations

R. H. Acosta, L. Agulles-Pedrós, S. Komin, D. Sebastiani, H. W. Spiess, P. Blümler
2006 Physical Chemistry, Chemical Physics - PCCP  
The dependence of the individual mean square displacement of rare gases in binary mixtures is studied by a combined experimental and theoretical approach. We show that the diffusion constant can be varied in a considerable range by changing the molar fractions of the mixtures. On the experimental side, NMR diffusion measurements are done on hyperpolarized 3 He and 129 Xe, mixed with several inert buffer gases, in the presence of a magnetic field gradient. The results are compared to diffusion
more » ... efficients obtained from atomistic molecular dynamics simulations based on Lennard-Jones type potentials of the corresponding gas mixtures, and to appropriate analytical expressions, yielding very good mutual agreement. This study is the first quantitative validation of the effects of the mutual interactions between gas particles on the individual diffusion properties. It is shown that the dependency of gas phase diffusion properties on the local chemical environment may not be neglected, e.g. in diffusion-controlled chemical reactions.
doi:10.1039/b609316g pmid:16971986 fatcat:7llxe2iz5jhsvibrdga2ak2zym