Interaction of rhodium with hydroxylated alumina model substrates

• Published in: Surface science 1997-07, Vol.384 (1), p.106-119
• Main Authors: Libuda, J., Frank, M., Sandell, A., Andersson, S., Brühwiler, P.A., Bäumer, M., Mårtensson, N., Freund, H.-J.
• Format: Article
• Language: English
• Subjects: Aluminum; Aluminum oxide; Applied sciences; Chemisorption; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Growth; Low energy electron diffraction; Materials science; Metals. Metallurgy; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Rhodium; Soft X-ray photo-electron spectroscopy; Solid surfaces and solid-solid interfaces; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Water
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(97)00170-2

In order to investigate how metal growth and metal-oxide interaction depend on the chemical properties of oxide surfaces, we describe a modification procedure which allows the introduction of surface hydroxyl groups on a well-ordered Al 2O 3 film on NiAl(110). The modification — based on deposition of metallic Al and subsequent water exposure — is characterized using LEED spot-profile analysis (SPA-LEED) and high-resolution photoelectron spectroscopy (PES). Upon Al deposition, small aggregates are formed, which are oxidized completely in the final preparation step as verified via PES. The presence of OH-groups is supported by the appearance of additional Al 2p and O 1s surface features. The origin of oxide core and valence level binding energy shifts induced by the modification procedure is discussed. Growth and metal-substrate interaction of Rh deposited onto the hydroxylated Al 2O 3 film is compared to Rh growth on the non-modified oxide surface. It is shown that at 300 K nucleation preferentially occurs on modified oxide areas (SPA-LEED). Photoelectron spectroscopy of both oxide and rhodium core levels points to a direct chemical interaction between the metal and surface hydroxyl groups.