Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)

O 44.50: Poster

Mittwoch, 28. März 2007, 17:00–19:30, Poster C

Microscopic picture of adsorption and desorption of D2O processed Au nanoparticles onto amino-terminated SiO2 surface studied by in situ ATR-SEIRA spectroscopy — •Tadaaki NAGAO^1,2, Dominik ENDERS^1,2, and Tomonobu NAKAYAMA^1,2 — ¹National Institue for Materials Science (NIMS), Tsukuba — ²ICORP-JST

By use of ATR-SEIRA spectroscopy, we revealed the microscopic mechanism of the adsorption and the desorption process of Au nanoparticles onto amino-terminated SiO2 surface. In order to avoid overlapping the faint C-H peak with the strong O-H peak, we used Au nanoparticles produced in D2O solution instead of those processed in normal H2O solution. In this way, we could sensitively detect the C-H signal of the ligand citric molecules directly covering the Au nanoparticles as well as the O-D peaks of the D2O near the nanoparticles. By combining the in situ ATR-SEIRA spectroscopy and the ex situ SEM observations, we successfully explain the reason of the observed Langumuir kinetics of the nanoparticle adsorption, and further we correlate the surface number density of the particles and their morphology (uniform distribution vs. aggregates) to the status of the ligand citrate molecules. When the adsorbed nanoparticles are exposed to the solution of aminoethanethiol (AET: small thiol molecule terminated with amino group), the nanoparticles desorb via two-step substitutional adsorption of the molecules, and are removed completely from the SiO2 substrate.