title: Pore Topology Effects in Positron Annihilation Spectroscopy of Zeolites.
abstract: Positron annihilation spectroscopy (PAS) is a powerful method to study the size and connectivity of pores in zeolites. The lifetime of positronium within the host material is commonly described by the Tao-Eldrup model. However, one of its largest limitations arises from the simple geometries considered for the shape of the pores, which cannot describe accurately the complex topologies in zeolites. Here, an atomic model that combines the Tao potential with the crystallographic structure is introduced to calculate the distribution and lifetime of Ps intrinsic to a given framework. A parametrization of the model is undertaken for a set of widely applied zeolite framework types (*BEA, FAU, FER, MFI, MOR, UTL), before extending the model to all known structures. The results are compared to structural and topological descriptors, and to the Tao-Eldrup model adapted for zeolites, demonstrating the intricate dependence of the lifetime on the pore architecture.
authors.affiliation: Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.
authors.forename: Asier
authors.initials: A
authors.lastname: Zubiaga
authors.affiliation: Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.
authors.forename: Robbie
authors.initials: R
authors.lastname: Warringham
authors.affiliation: Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.
authors.forename: Sharon
authors.initials: S
authors.lastname: Mitchell
authors.affiliation: Institute for Particle Physics, Department of Physics, ETH Zurich, Otto-Stern-Weg 5, 8093, Zurich, Switzerland.
authors.forename: Lars
authors.initials: L
authors.lastname: Gerchow
authors.affiliation: Institute for Particle Physics, Department of Physics, ETH Zurich, Otto-Stern-Weg 5, 8093, Zurich, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Cooke
authors.affiliation: Institute for Particle Physics, Department of Physics, ETH Zurich, Otto-Stern-Weg 5, 8093, Zurich, Switzerland.
authors.forename: Paolo
authors.initials: P
authors.lastname: Crivelli
authors.affiliation: Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093, Zurich, Switzerland.
authors.forename: Javier
authors.identifier: http://orcid.org/0000-0002-5805-7355
authors.initials: J
authors.lastname: Pérez-Ramírez
keywords: Tao-Eldrup model; pore topology; positron annihilation spectroscopy; positronium lifetime; zeolites