Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 40: Particles and Clusters I

O 40.3: Talk

Wednesday, March 28, 2007, 16:15–16:30, H38

In Situ Surface Enhanced Infrared Absorption Spectroscopy for the Analysis of the Adsorption and Desorption Process of Au Nanoparticles on the SiO2/Si Surface — •Dominik Enders^1,2, Tadaaki Nagao^1,2, and Tomonobu Nakayama^1,2 — ¹National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044, Japan — ²Nanoscale Quantum Conductor Array Project, ICORP, JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

The adsorption and desorption of Au nanoparticles (AuNP) in colloidal D2O suspension on the SiO2/Si surface was investigated by in situ ATR-IR spectroscopy. With increasing surface density of AuNP the absorption of the vibrational modes of D2O and of the citrate molecules covering the AuNP increases due to surface enhanced infrared absorption (SEIRA). We show that the adsorption kinetics can be investigated by monitoring the molecular vibrational modes of D2O and the citrate molecules, and furthermore we clarify that the adsorption process can be described very well by a Langmuir-kinetics model. When exposing a saturated AuNP submonolayer to 2-aminoethanethiol/D2O solution, the AuNP are removed from the surface and the IR absorption of the D2O vibrational modes become weaker again. Taking into account the time dependencies of the CH and the OD peaks, we propose a microscopic model explaining the mechanism of the desorption process.