title: Noninvasive bipolar double-pulsed-field-gradient NMR reveals signatures for pore size and shape in polydisperse, randomly oriented, inhomogeneous porous media.
abstract: Noninvasive characterization of pore size and shape in opaque porous media is a formidable challenge. NMR diffusion-diffraction patterns were found to be exceptionally useful for obtaining such morphological features, but only when pores are monodisperse and coherently placed. When locally anisotropic pores are randomly oriented, conventional diffusion NMR methods fail. Here, we present a simple, direct, and general approach to obtain both compartment size and shape even in such settings and even when pores are characterized by internal field gradients. Using controlled porous media, we show that the bipolar-double-pulsed-field-gradient (bp-d-PFG) methodology yields diffusion-diffraction patterns from which pore size can be directly obtained. Moreover, we show that pore shape, which cannot be obtained by conventional methods, can be directly inferred from the modulation of the signal in angular bp-d-PFG experiments. This new methodology significantly broadens the types of porous media that can be studied using noninvasive diffusion-diffraction NMR.
authors.affiliation: School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Noam
authors.initials: N
authors.lastname: Shemesh
authors.forename: Evren
authors.initials: E
authors.lastname: Ozarslan
authors.forename: Tal
authors.initials: T
authors.lastname: Adiri
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Basser
authors.forename: Yoram
authors.initials: Y
authors.lastname: Cohen
mesh_terms: D016880:Anisotropy; D004058:Diffusion; D009682:Magnetic Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D016062:Porosity