Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/106827
Type: Artigo
Title: Crystallographic structure of ultra-thin films of Pd on Ni(1 1 1) and Ni on Pd(1 1 1) studied by photoelectron diffraction
Author: Nascente, P. A. P.
Carazzolle, M. F.
Siervo, A. de
Maluf, S. S.
Landers, R.
Kleiman, G. G.
Abstract: We report studies of ultra-thin films of Pd and Ni deposited on Ni(1 1 1) and Pd(1 1 1) surfaces, respectively, using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), and X-ray photoelectron diffraction (XPD). For a 1.5 ML Pd film deposited on Ni(1 1 1) at room temperature, XPS indicates that Pd grows in a layer-by-layer fashion and does not diffuse on the Ni substrate, whereas LEED exhibits a reconstructed pattern, which can be attributed to a distribution of bi-dimensional islands on the surface with a lateral lattice parameter different from that of Ni(1 1 1). Annealing the film at 650 °C produces a (1 × 1) LEED pattern, which suggests Pd diffusion and alloy formation. By using a systematic XPD analysis, we were able to determine that Pd diffused at least to the fourth layer into the Ni(1 1 1) substrate in low concentrations (10-20%), and that 75% of the surface remained covered by Pd bi-dimensional islands. The complementary system, Ni on Pd(1 1 1), presented similar LEED and XPS results. The comparison between experimental and theoretical XPD results indicated that the surface was partially covered by Ni islands (50-60%), and the other part was formed by random NixPd100-x surface alloy. © 2007 Elsevier B.V. All rights reserved.
We report studies of ultra-thin films of Pd and Ni deposited on Ni(1 1 1) and Pd(1 1 1) surfaces, respectively, using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), and X-ray photoelectron diffraction (XPD). For a 1.5 ML Pd film deposited on Ni(1 1 1) at room temperature, XPS indicates that Pd grows in a layer-by-layer fashion and does not diffuse on the Ni substrate, whereas LEED exhibits a reconstructed pattern, which can be attributed to a distribution of bi-dimensional islands on the surface with a lateral lattice parameter different from that of Ni(1 1 1). Annealing the film at 650 ?C produces a (1 × 1) LEED pattern, which suggests Pd diffusion and alloy formation. By using a systematic XPD analysis, we were able to determine that Pd diffused at least to the fourth layer into the Ni(1 1 1) substrate in low concentrations (10-20%), and that 75% of the surface remained covered by Pd bi-dimensional islands. The complementary system, Ni on Pd(1 1 1), presented similar LEED and XPS results. The comparison between experimental and theoretical XPD results indicated that the surface was partially covered by Ni islands (50-60%), and the other part was formed by random NixPd100?x surface alloy.
We report studies of ultra-thin films of Pd and Ni deposited on Ni(1 1 1) and Pd(1 1 1) surfaces, respectively, using X-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), and X-ray photoelectron diffraction (XPD). For a 1.5 ML Pd film deposited on Ni(1 1 1) at room temperature, XPS indicates that Pd grows in a layer-by-layer fashion and does not diffuse on the Ni substrate, whereas LEED exhibits a reconstructed pattern, which can be attributed to a distribution of bi-dimensional islands on the surface with a lateral lattice parameter different from that of Ni(1 1 1). Annealing the film at 650 ◦C produces a (1 × 1) LEED pattern, which suggests Pd diffusion and alloy formation. By using a systematic XPD analysis, we were able to determine that Pd diffused at least to the fourth layer into the Ni(1 1 1) substrate in low concentrations (10–20%), and that 75% of the surface remained covered by Pd bi-dimensional islands. The complementary system, Ni on Pd(1 1 1), presented similar LEED and XPS results. The comparison between experimental and theoretical XPD results indicated that the surface was partially covered by Ni islands (50–60%), and the other part was formed by random NixPd100−x surface alloy.
Subject: Radiação sincrotrônica
Filmes de níquel
Espectroscopia fotoeletrônica de raio X
Difração eletrônica em baixa energia
Country: Holanda
Editor: Elsevier
Citation: Journal Of Molecular Catalysis A: Chemical. , v. 281, n. 1-2, p. 3 - 8, 2008.
Rights: fechado
Identifier DOI: 10.1016/j.molcata.2007.09.021
Address: https://www.sciencedirect.com/science/article/pii/S1381116907005602
Date Issue: 2008
Appears in Collections:IFGW - Artigos e Outros Documentos

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