Regensburg 2002 – wissenschaftliches Programm
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O: Oberflächenphysik
O 26: Postersitzung (Rastersondentechniken, Nanostrukturen, Teilchen und Cluster, Methodisches, Oxide und Isolatoren, Grenzfl
äche fest-flüssig, Struktur und Dynamik reiner Oberfl
ächen, Oberfl
ächenreaktionen, Zeitaufg. Spektroskopie, Phasenüberg
änge
O 26.32: Poster
Mittwoch, 13. März 2002, 14:30–17:30, Bereich C
In situ TEM investigation of the growth of Pd particles on carbon substrates at elevated temperatures and oxygen partial pressures. — •Rainer Anton1, Dietmar Junkereit1, and Alexandr Kryshtal2 — 1Institut für Angewandte Physik, Universität Hamburg, Jungiusstrasse 11, D-20355 Hamburg — 2V.N. Karazin Kharkov National University, 4 Svobody sq., 61077 Kharkov, Ukraine
The influence of active gases on the nucleation and growth of Pd particles on amorphous carbon and on crystalline graphite (HOPG) is investigated. Deposition experiments are performed in a specially modified transmission electron microscope, and the particle growth kinetics is recorded in real time. The base pressure is about 8·10−9 mbar. At substrate temperatures around 750 K, admission of oxygen up to 5·10−6 mbar during deposition causes growth of well-ordered crystallites with pronounced facetting on both types of substrates. On HOPG, these are perfectly epitaxially oriented, and, most conspicuously, even large crystallites are highly mobile, while maintaining their shape and orientation. During and after growth under oxygen, particles catalyze the oxidation of the carbon, producing grooves or holes in the substrate. The activity shows a strong correlation with particle facetting and orientation.