Structure and morphology of nanometer-sized Pd clusters grown at high temperature on natural graphite single crystals
CRMC2 (Laboratoire associated to the Universities of Aix-Marseille 2 and 3) -CNRS, Campus de Luminy, Case 913, 13288 Marseille Cedex 9, France
2 GPEC, Campus de Luminy, Case 901, 13288 Marseille Cedex 9, France
Corresponding author: email@example.com
Revised: 25 September 2000
Accepted: 20 October 2000
Published online: 15 January 2001
Performing both ex situ transmission electron microscopy (TEM) and in situ scanning tunnelling microscopy (STM) experiments on the same samples, we have characterized in detail a model catalyst (Pd/graphite). The Pd clusters were epitaxially grown at high temperature on clean natural graphite substrates under ultra high vacuum (UHV) conditions. For the chosen growth conditions the density of clusters is rather low (109 cm−2), and their size is typically few tens of nanometers. TEM diffraction studies reveal that most of the clusters (92% ) are in a same epitaxial orientation which is defined by: (1 1 1)Pd (0 0 . 1)Gr and . Moreover, both STM imaging and TEM observations show that the clusters have truncated tetrahedron shapes. The combination of TEM and STM characterizations of the same samples appears to be a very efficient way to get a detailed knowledge of the global properties of a collection of supported clusters (spatial and size distributions) as well as of their individual properties (structure, morphology).
PACS: 61.46.+w – Clusters, nanoparticules, and nanocrystalline materials / 61.16.Bg – Transmission, reflection and scanning electron microscopy (including EBIC) / 61.16. Ch – Scanning probe microscopy: scanning tunneling, atomic force, scanning optical, magnetic force, etc.
© EDP Sciences, 2001