Electronic properties of Sn/Pd intermetallic compounds on Pd(1 1 0)

• Published in: Surface science Vol. 595; no. 1; pp. 138 - 150
• Main Authors: Tsud, N., Skála, T., Šutara, F., Veltruská, K., Dudr, V., Fabík, S., Sedláček, L., Cháb, V., Prince, K.C., Matolín, V.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05.12.2005; Amsterdam Elsevier Science; New York, NY
• Subjects: CO adsorption; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Low-energy electron diffraction; Metal–metal interfaces; Palladium; Physics; Synchrotron radiation; Tin; X-ray photoelectron spectroscopy; Metal–metal interfaces; CO adsorption; Tin; Low-energy electron diffraction; Palladium; X-ray photoelectron spectroscopy; Synchrotron radiation; Inorganic compounds; Intermetallic compounds; Coadsorption; Transition element compounds; Transition elements; Metal-metal interfaces; LEED; X-ray photoelectron spectra
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2005.08.003

We have studied the Sn/Pd(1 1 0) adsorption system by synchrotron radiation photoelectron spectroscopy and low-energy electron diffraction (LEED). For room temperature evaporation, two surface reconstructions were observed: c(2 × 2) and (3 × 1), corresponding to about 0.5 ML and 0.75 ML of Sn adlayer coverage. The Pd 3d and Sn 4d core levels as well as valence band spectra indicate a strong chemical interaction between Sn and Pd, and the formation of an intermetallic interface. Structural models are proposed for both of these phases based on the photoemission and CO adsorption results. We show that at coverage higher than 0.7 ML, tin is alloyed with the Pd crystal forming a subsurface layer of Pd–Sn intermetallic compound of stoichiometry which varies with tin coverage. CO adsorption occurs only at low temperature (120 K) and depends on the Sn coverage and reconstruction of the Pd(1 1 0) surface. We estimate the CO adsorption energy for the c(2 × 2)- and (3 × 1)-Sn/Pd(1 1 0) surfaces to be reduced by 40% compared to the clean palladium (1 1 0) surface.