Holography of clean and sulphur-covered Ni(111) using multiple wave number photoelectron diffraction patterns

• Published in: Surface science Vol. 334; no. 1; pp. 114 - 134
• Main Authors: Zharnikov, M., Weinelt, M., Zebisch, P., Stichler, M., Steinrück, H.-P.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 10.07.1995; Amsterdam Elsevier Science; New York, NY
• Subjects: Applied sciences; Chalcogens; Chemisorption; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Metals. Metallurgy; Nickel; Photoelectron diffraction; Photoelectron holography; Physics; Solid surfaces and solid-solid interfaces; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Chemisorption; Chalcogens; Nickel; Photoelectron holography; Photoelectron diffraction; Surface reconstruction; Electron diffraction; Transition elements; Holography; Experimental study; Sulfur; Photoelectron spectroscopy; Image reconstruction; Surface structure
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(95)00465-3

Angular distributions of Ni 3 p 3 2 photoelectrons for clean Ni(111) and of S 2 p 3 2 photoelectrons for the p(2 × 2)S and (5√3 × 2)S structures on Ni(111) were measured at seven different kinetic energies ranging from 239 to 417 eV for Ni 3 p 3 2 and from 130 to 322.5 eV for S 2 p 3 2 . From the photoelectron diffraction patterns, holographic reconstructions were performed using (1) the single wave number reconstruction method and (2) the multiple wave number phased sum method. For the clean surface, neighboring atoms in the plane of the emitter and some atoms in the second and third plane above the emitter can be identified; the holographic reconstruction in the first plane above the emitter is however dominated by intense artifacts. For Ni(111)-p(2 × 2)S, the three-fold hollow fcc adsorption site of sulphur can be unequivocally identified with a distance to the first Ni layer of about 1.6 Å. Holographic reconstructions for Ni(111)-(5√3 × 2)S allow to exclude the three-fold hollow position of sulphur and disagree with a proposed mixing of different non-symmetric adsorption sites. The distance of the sulphur atoms from the top Ni layer is determined to 1.1–1.2 Å. The reconstructions are consistent with a quasi-(100) reconstruction of the Ni(111) crystal surface. For all systems the potential of using only an azimuthal sector instead of the full hemispherical holograms for the reconstruction is discussed.