title: Electrostatic aggregation and formation of core-shell suprastructures in binary mixtures of charged metal nanoparticles.
abstract: Electrostatic aggregation of oppositely charged silver and gold nanoparticles leads to the formation of core-shell clusters in which the shell is formed by the nanoparticles, which are in excess. Arguments based on Debye screening of interactions between like-charged particles help explain why these clusters are stable despite possessing net electric charge. The core-shell aggregates exhibit unusual optical properties with the resonance absorption of the shell particles enhanced by the particles in the core and that of the core suppressed by the shell. Experimental UV-vis absorption spectra are faithfully reproduced by Mie theory. The modeling allows for estimation of the numbers of particles forming the shell and of the shell's effective thickness. These theoretical predictions are substantiated by experiments using nanoparticles covered with different combinations of charged groups and performed at different values of pH.
authors.affiliation: Department of Chemical and Biological Engineering and The Northwestern Institute on Complex Systems, Northwestern University, Evanston, Illinois 60208, USA.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Kalsin
authors.forename: Anatoliy O
authors.initials: AO
authors.lastname: Pinchuk
authors.forename: Stoyan K
authors.initials: SK
authors.lastname: Smoukov
authors.forename: Maciej
authors.initials: M
authors.lastname: Paszewski
authors.forename: George C
authors.initials: GC
authors.lastname: Schatz
authors.forename: Bartosz A
authors.initials: BA
authors.lastname: Grzybowski
mesh_terms: D045424:Complex Mixtures / Q000737:chemistry; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D004563:Electrochemistry / Q000379:methods; D046911:Macromolecular Substances / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D055672:Static Electricity
chemical_list: D045424:Complex Mixtures; D046911:Macromolecular Substances; D008670:Metals