On the geometrical and electronic structure of an ultra-thin crystalline silica film grown on Mo(112)

Abstract

Abstract. The atomic structure of a well-ordered silica film grown on a Mo(112) single crystal substrate is discussed in detail using the experimental and theoretical results available to date. New photoelectron spectroscopy results using synchrotron radiation and ultraviolet spectroscopy data are presented. The analysis unambiguously shows that the ultra-thin silica film consists of a two-dimensional network of corner sharing [SiO 4 ] tetrahedra chemisorbed on the unreconstructed Mo(112) surface. The review also highlights the important role of theoretical calculations in the determination of the atomic structure of the silica films and in interpretation of experimental data.

Formation of one-dimensional molybdenum oxide on Mo(112)

“…Nevertheless, the O 1s signal was used to calibrate the amount of oxygen on the (2x3) surface by comparison with the spectra of an ultra-thin silica film grown on the same Mo(112) substrate, for which the atomic structure has recently been determined [37,38] [42]. In the case of ultra-thin oxide films, additional screening by a m etal substrate underneath the film may result in lowering of the measured BE values.…”

Growth and Structure of Crystalline Silica Sheet on Ru(0001)

“…Such a hexagonal prism slab, which is similar to double layer structures found in sheet silicates [12], has been proposed as a model for hydrophobic silica surfaces [29]. It was previously considered as a possible model for the silica film on Mo(112), but discarded because of disagreement with the experimental results [3]. This structure possesses a Si-O-Si linkage normal to the surface suggested by the IRAS results.…”

“…For better understanding of structureproperty relationships on silica-based materials, particularly of reduced dimensions, thin silica films grown on metal single crystal substrates are suggested as suitable model systems that allow the facile application of many ''surface science'' techniques. It has recently been shown that crystalline silica films and nanowires can be grown on Mo(112) [1][2][3][4][5]. The ultrathin film consists of a monolayer honeycomblike network of corner-sharing [SiO 4 ] tetrahedra, thus resulting in a SiO 2:5 stoichiometry of the film.…”

“…Also, the XPS results exclude silicide formation (as it was the case for the preparation of silica films on Ni(111) [11]). The integral amounts of Si in the films were determined to be approximately twice that of the monolayer silica film on Mo(112) used as a reference material with a well-established structure [2,3].…”

“…[For comparison, the topmost (Si-O-Si) and interfacial (Si-O-Mo) oxygen species in SiO 2:5 =Moð112Þ films exhibited the BEs at 532.5 and 531.3 eV, respectively, with the signal ratio 3:2 [2,3]. The additional oxygen species having bonds only to the Mo(112) surface in the so-called ''O-rich'' structures [22] showed a weak signal at 530.6 eV, i.e., at the BEs close to that observed on O=Moð112Þ.]…”