title: Langevin and fOkker-Planck analyses of inhibited molecular passing processes controlling transport and reactivity in nanoporous materials.
abstract: Inhibited passing of reactant and product molecules within the linear pores of nanoporous catalytic materials strongly reduces reactivity. The dependence of the passing propensity P on pore radius R is analyzed utilizing Langevin dynamics to account for solvent effects. We find that P ∼ (R-R(c))(σ), where passing is sterically blocked for R≤R(c), with σ below the transition state theory value. Deeper insight comes from analysis of the corresponding high-dimensional Fokker-Planck equation, which facilitates an effective small-P approximation, and dimensional reduction enabling utilization of conformal mapping ideas. We analyze passing for spherical molecules and also assess the effect of rotational degrees of freedom for elongated molecules.
authors.affiliation: Ames Laboratory-U.S. DOE, Iowa State University, Ames, Iowa 50011, USA and Department of Mathematics, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Chi-Jen
authors.initials: CJ
authors.lastname: Wang
authors.affiliation: Ames Laboratory-U.S. DOE, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Ackerman
authors.affiliation: Ames Laboratory-U.S. DOE, Iowa State University, Ames, Iowa 50011, USA and Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Igor I
authors.initials: II
authors.lastname: Slowing
authors.affiliation: Ames Laboratory-U.S. DOE, Iowa State University, Ames, Iowa 50011, USA and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Evans
mesh_terms: D004058:Diffusion; D008956:Models, Chemical; D058608:Nanopores