Oxide Surfaces Single Crystals, Powders, Thin Films

1 Oxide Surfaces Single Crystals, Powders, Thin Films 

Oxide surfaces in normal conditions are generally covered by OH groups as they have the tendency to interact with water from the atmosphere leading to water dissociation and surface hydroxylation. Polycrystalline oxides present a very complex surface morphology, a high number of defects, pores, impurities, etc., and their use for detailed studies of metal upport interactions present 

All the oxide surfaces used to deposit metal clusters in controlled conditions need to be well characterized both structurally and electronically. As we mentioned above, thin oxide films allow one to use a variety of spectroscopies. 

In general, the good quality of the substrate is essential to analyze in detail the properties of the supported nanoclusters. In fact, as we will discuss below, the cluster-oxide interaction is such to influence the shape and the electronic structure of the deposited cluster. A deep understanding of the cluster properties needs therefore a similarly profound knowledge of the interface bonding. Furthermore, a precise knowledge of the surface structure is essential to design realistic theoretical models. 

---

We have undertaken a series of experiments Involving thin film models of such powdered transition metal catalysts (13,14). In this paper we present a brief review of the results we have obtained to date Involving platinum and rhodium deposited on thin films of tltanla, the latter prepared by oxidation of a tltanliua single crystal. These systems are prepared and characterized under well-controlled conditions. We have used thermal desorption spectroscopy (TDS), Auger electron spectroscopy (AES) and static secondary Ion mass spectrometry (SSIMS). Our results Illustrate the power of SSIMS In understanding the processes that take place during thermal treatment of these thin films. Thermal desorption spectroscopy Is used to characterize the adsorption and desorption of small molecules, In particular, carbon monoxide. AES confirms the SSIMS results and was used to verify the surface cleanliness of the films as they were prepared. 

---