Preparation of Polydivinylbenzene/Au Core-Shell Beads

A novel core-shell material composed of closely packed gold shells on poly (divinylbenzene) (PDVB) cores was fabricated via the reduction of a gold complex. PDVB beads (2-5 +m) were synthesized by precipitation polymerization. The surface of the PDVB beads was modified by three different methods, viz. sulfonation, chloromethylation, and thiolation. The modification of the surface of the PDVB beads was designed to allow the facile attachment of the gold layer onto the PDVB cores. The gold seeding layer was initially formed on the modified PDVB cores by the chemical reduction of a gold-phenanthroline complex. The subsequent growing reactions of NH2OH and HAuCl4 increased the gold coverage to more than 90%. The structure of the PDVB/Au core-shell material was characterized by SEM, XPS, and FT-IR.

In situ investigation of growth of gold on crystalline TiO2 and amorphous Al2O3 substrates

ABSTRACTThe growth of thin gold films on highly crystalline TiO2 and amorphous Al2O3 substrates and its dependence on substrate temperature was investigated under UHV-conditions by in situ internal stress measurements. Deposition of gold on amorphous Al2O3 at substrate temperatures between 27°C and 300°C shows a stress vs. thickness curve which indicates island growth at first and the formation of a polycrystalline film at higher thickness. A comparable stress vs. thickness curve is found for the growth of gold on the highly crystalline TiO2 substrate at substrate temperatures below 200°C, again indicating island growth. At higher temperatures, however, a new tensile stress feature at low gold coverage is interpreted to indicate the formation of a strained interface layer. This strain in the gold film is eliminated after deposition of a few monolayers most likely through incorporation of dislocations and defects. The growth stress at higher film thickness is indicative of island film growth.

FORMATION OF $\sqrt {21} \times \sqrt {21} $ STRUCTURE BY GOLD DEPOSITION ON ${\rm{Si}}\left( {111} \right)\sqrt 3 \times \sqrt 3\mbox{-}{\rm{Ag}}$ SURFACE AND THE WAVERING BEHAVIOR

Initial stage of gold deposition on a [Formula: see text] surface at room temperature is observed by reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). At gold coverage of 0.14 monolayer (ML) (here 1 ML=7.8×1014 atoms/cm2) a [Formula: see text] structure is formed on the surface. A model of the superstructure is proposed in terms of an embedded arrangement of three gold atoms in the unit cell. Wavering behavior of [Formula: see text] islands formed on the [Formula: see text] structure is found during STM observations.