Ordered and disordered oxygen and sulfur on Ni(100)

The adsorption geometry of sulphur on Ir{100}: A quantitative LEED study

“…This is indicated by the bond lengths of 2.36 Å and 2.37 Å for p(2 · 2)-S and c(2 · 2)-S respectively, as compared to the value of 2.39 Å expected from the covalent radius of S (based on the 2.05 Å bond length of S 2 and the metallic radius of Ir, 1.36 Å [38]). Similar behaviour was observed on Cu [41], Ni [7], Pd [8,9], Mo [42] and Rh [10][11][12] surfaces.…”

“…Ir{1 0 0}-c(2 · 2)-S: structure determination Atomic adsorbates at low coverages tend to adsorb on well-defined sites. S is generally found to adsorb on fourfold symmetric hollow sites on fcc{1 0 0} surfaces of transition metals such as Ni [7], Pd [8,9], Rh [10][11][12] and Cu [41]. In order to exclude any unlikely geometric configuration, we tested as a first step three types of structures, shown in Fig.…”

“…On fcc{1 0 0} surfaces of transition metals such as Pt [4][5][6], Ni [7], Pd [8,9] and Rh [10][11][12], adsorption of sulphur normally leads to the formation of a p(2 · 2) overlayer followed by a c(2 · 2) overlayer with increasing coverage. A large number of structural studies on the chemisorption of S on fcc{1 0 0} surfaces using a variety of techniques have been carried out [7][8][9][10][11][12][13]. In all these studies, sulphur has been found to adsorb in the symmetric fourfold hollow site.…”

Geometrical, spectroscopic, and magnetic properties of an oxygen atom adsorbed on the Ni(100) surface

“…From the analysis of diffuse low-*Permanent address: Ecole Normale Superieure de Chimie, 8 [19], performed on both c(2 X 2) and p(2 X 2) oxygen-Ni(100) phases, does not confirm the off-center position. SEXAFS [4,6], TCT [16], STM [15], LEED and DLEED [1,3], and HREELS [lo, 11,201 studies strongly support the high-symmetry fourfold hollow site. From the majority of these structural studies, the adsorbate spacing between oxygen and first-layer nickel atoms fall in the range 0.8-0.9 A.…”

“…Oxygen adsorption on the Ni(100) surface has been studied by a variety of experimental techniques including low-energy electron diffraction (LEED) [ 1,3], surface extended X-ray adsorption fine structure ( S E W S ) [4-61, X-ray adsorption near-edge structure (XANES) [7], electron energy loss spectroscopy (EELS) [8,9], and highresolution electron energy loss spectroscopy (HREELS) [lo, 111, normal photoelectron diffraction (NPD) [ 12,131, high-energy ion scattering (HEIS) [ 141, scanning tunneling microscopy (STM) [ 151, and transmission channeling technique (TcT) …”