title: Microemulsion-based synthesis of nanoscaled silver hollow spheres and direct comparison with massive particles of similar size.
abstract: Nanoscale silver hollow spheres are first prepared via a microemulsion approach with 15-20 nm as the outer diameter, 3-5 nm as the wall thickness, and 10-15 nm as the diameter of the inner cavity. The presence of hollow spheres is confirmed by electron microscopy (SEM, BF-/HAADF-STEM, HRTEM) as well as by X-ray diffraction with a line-shape analysis to characterize the microcrystalline properties. In addition to the hollow spheres, massive silver nanoparticles of similar size (outer diameter of 15-20 nm) are gained via microemulsions. Based on the similarity of experimental conditions and the resulting particle size, as-prepared silver hollow spheres and massive nanoparticles are used to compare their optical properties and surface-plasmon resonance. In contrast to reducing the diameter of massive particles, "hollowing" of silver nanoparticles leads to a red-shift of the plasmon resonance. With a red shift of about 33 nm in the case of the hollow spheres, a quantum-size effect is indeed observed and in accordance with the thin sphere wall.
authors.affiliation: Institut für Anorganische Chemie, Karlsruhe Institute of Technology, Engesserstrasse 15, D-76131 Karlsruhe, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Kind
authors.forename: Radian
authors.initials: R
authors.lastname: Popescu
authors.forename: Erich
authors.initials: E
authors.lastname: Müller
authors.forename: Dagmar
authors.initials: D
authors.lastname: Gerthsen
authors.forename: Claus
authors.initials: C
authors.lastname: Feldmann
mesh_terms: D000465:Algorithms; D003460:Crystallization; D004655:Emulsions; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008863:Microspheres; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D012834:Silver / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D020349:Surface Plasmon Resonance; D014961:X-Ray Diffraction
chemical_list: D004655:Emulsions; D012834:Silver