title: Probing the mystery of Liesegang band formation: revealing the origin of self-organized dual-frequency micro and nanoparticle arrays.
abstract: Periodic precipitation processes in gels can result in impressive micro- and nanostructured patterns known as periodic precipitation (or Liesegang bands). Under certain conditions, the silver nitrate-chromium(vi) system exhibits the coexistence of two kinds of Liesegang bands with different frequencies. We now present that the two kinds of bands form independently on different time scales and the pH-dependent chromate(vi)-dichromate(vi) equilibrium controls the formation of the precipitates. We determined the spatial distribution and constitution of the particles in the bands using focused ion beam-scanning electron microscopy (FIB-SEM) and scanning transmission X-ray spectromicroscopy (STXM) measurements. This provided the necessary empirical input data to formulate a model for the pattern formation; a model that quantitatively reproduces the experimental observations. Understanding the pattern-forming process at the molecular level enables us to tailor the size and the shape of the bands, which, in turn, can lead to new functional architectures for a range of applications.
authors.affiliation: Laboratory for High Performance Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Überlandstrasse 129, Dübendorf, Switzerland. Rita.Toth@empa.ch ritatoth1113@gmail.com.
authors.forename: Rita
authors.initials: R
authors.lastname: Tóth
authors.affiliation: Department of Chemistry, University of Basel, Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Roché M
authors.initials: RM
authors.lastname: Walliser
authors.affiliation: Department of Physics, Budapest University of Technology and Economics, 1111, Budafoki út 8, Budapest, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Lagzi
authors.affiliation: Laboratory for High Performance Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Überlandstrasse 129, Dübendorf, Switzerland. Rita.Toth@empa.ch ritatoth1113@gmail.com and Department of Chemistry, University of Basel, Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Florent
authors.initials: F
authors.lastname: Boudoire
authors.affiliation: Department of Chemistry, University of Basel, Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Marcel
authors.initials: M
authors.lastname: Düggelin
authors.affiliation: Laboratory for High Performance Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Überlandstrasse 129, Dübendorf, Switzerland. Rita.Toth@empa.ch ritatoth1113@gmail.com.
authors.forename: Artur
authors.identifier: http://orcid.org/0000-0002-6992-7774
authors.initials: A
authors.lastname: Braun
authors.affiliation: Department of Chemistry, University of Basel, Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Housecroft
authors.affiliation: Department of Chemistry, University of Basel, Spitalstrasse 51, 4056 Basel, Switzerland.
authors.forename: Edwin C
authors.initials: EC
authors.lastname: Constable