The Chemical Educator
ISSN: 1430-4171 (electronic version)
Abstract Volume 13
Issue 3 (2008) pp 153-157
Layer-by-layer Self-Assembly of Colloidal Gold-Silica Multilayers
Zhenyuan Zhang, Dan Meisel, Prashant Kamat, Masaru Kuno*
Department of Chemistry and Biochemistry, Notre Dame
Radiation Laboratory, University of Notre Dame, Notre Dame, IN 46556,
Published online: 1 June 2008
Abstract. Strategies to obtain self-assembled monolayers (SAMs) of molecular entities as well as the underlying chemical principles leading to their formation have been described in the Journal.† Here we adopt similar principles to self-assemble monolayers of gold nanoparticles (NPs) in a layer-by-layer fashion. The gold particles provide the functionality of component atoms in what would otherwise constitute a conventional lattice. Several successive Au NP monolayers, each separated by a silica layer, are then added to create a three dimensional (3D) multilayer. During the assembly, the student tests the effect of the mediumís dielectric constant on the extinction spectrum of individual NP monolayers. Shifts in the plasmon band peak position illustrate the control one has over the optical and electrical properties of the 3D structure. Next, the student demonstrates through additional extinction measurements that no more than one Au NP monolayer is deposited at each step of the assembly when reaction conditions are judiciously chosen. Variations in the layer-by-layer deposition conditions may then be attempted to directly modify the extinction of the final structure.† The entire experiment illustrates the construction of 3D assemblies of nanostructured materials whose intralayer- and interlayer- interparticle electronic and spectroscopic interactions can be controlled.
Key Words: Laboratories and Demonstrations; analytical chemistry; physical chemistry; hands-on learning/manipulatives; colloids; materials science; nanotechnology; surface science; synthesis; UV/vis spectroscopy
(*) Corresponding author. (E-mail: firstname.lastname@example.org)
Supporting information describing the sequence of steps followed in the class and laboratory is available (42 KB).
Issue date: June