Berlin 2005 – wissenschaftliches Programm
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DS: Dünne Schichten
DS 23: Postersitzung I
DS 23.37: Poster
Freitag, 4. März 2005, 16:00–18:30, Poster TU B
IR-transmission spectroscopical and SEIRA study of Ag nanoparticles on MgO(001) — •Fanzhen Meng, Daniel Seilbel, Andreas Priebe, Matthias Lust, Olaf Skibbe, Robert Lovrincic, Gerhard Fahsold, and Annemarie Pucci — Kirchhoff-Institut für Physik, Universität Heidelberg
Temperature and deposition rate have big effects on ultrathin films’ morphologies. In this work we investigate Ag/MgO(001) grown at different temperatures (from 60 K to 500 K) and also with different deposition rates with in-situ IR spectroscopy. With liquid Helium cooling we get a smooth film morphology. IR transmittance spectra show that this film becomes conductive at about 1 nm thickness. At 500 K, we get a film with big and separated facets. At 40 nm deposited thickness we still have separated islands at this temperature. At room temperature and 100 K, with a higher deposition rate the percolation is shifted towards lower thickness. We calculated the transmission spectra with a Drude-type model and with an effective medium model.
We also exposed CO to these films at low temperatures (60 K and 100 K). CO-vibration peaks give different information when adsorbed on films grown at different temperatures. For example, we can not find any CO signal at 100 K and at 60 K on a film which was prepared at room temperature. At 100 K, we find a Boudouard reaction (CO+CO=CO2+C) when exposure CO to films which were prepared at 400 K and 500 K.