Preparation of silica films on Ru(0001): A LEEM/PEEM study

Klemm, Hagen W.; Peschel, Gina; Madej, Ewa; Fuhrich, Alexander; Timm, Martin; Menzel, D.; Schmidt, Thomas; Freund, Hans‐Joachim

doi:10.1016/j.susc.2015.05.017

Cited by 20 publications

(41 citation statements)

References 40 publications

(34 reference statements)

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“…Both the intensity and the full width at the half maximum (FWHM) of the O 1 s and Si 2p remain unchanged, indicating that the chemical composition and bonding configuration of the silica film stay intact. The increase in binding energies can be attributed to changes of the chemical states on the Ru substrate [13,37,38]. As shown in Fig.…”

Section: Resultsmentioning

confidence: 91%

Energy Level Shifts at the Silica/Ru(0001) Heterojunction Driven by Surface and Interface Dipoles

et al. 2016

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Charge redistribution at heterogeneous interfaces is a fundamental aspect of surface chemistry. Manipulating the amount of charges and the magnitude of dipole moments at the interface in a controlled way has attracted tremendous attention for its potential to modify the activity of heterogeneous catalysts in catalyst design. Two-dimensional ultrathin silica films with well-defined atomic structures have been recently synthesized and proposed as model systems for heterogeneous catalysts studies. R. Wlodarczyk et al. (Phys. Rev. B, 85, 085403 (2012)) have demonstrated that the electronic structure of silica/ Ru(0001) can be reversibly tuned by changing the amount of interfacial chemisorbed oxygen. Here we carried out systematic investigations to understand the underlying mechanism through which the electronic structure at the silica/Ru(0001) interface can be tuned. As corroborated by both in situ X-ray photoelectron spectroscopy and density functional theory calculations, the observed interface energy level alignments strongly depend on the surface and interfacial charge transfer induced dipoles at the silica/ Ru(0001) heterojunction. These observations may help to understand variations in catalytic performance of the model system from the viewpoint of the electronic properties at the confined space between the silica bilayer and the Ru(0001) surface. The same behavior is observed for the aluminosilicate bilayer, which has been previously proposed as a model system for zeolites.Jian-Qiang Zhong and Mengen Wang contributed equally to this work.

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Section: Resultsmentioning

confidence: 91%

Energy Level Shifts at the Silica/Ru(0001) Heterojunction Driven by Surface and Interface Dipoles

et al. 2016

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“… 31 Klemm et al explored mesoscale structures in the presence of large step bunches and concluded that monolayer phases were prevalent near these step bunches. 32 Because those studies were performed with LEEM/PEEM, it was not possible to discern individual atomic steps or the prevalence of coexisting phases with smaller domain sizes. Here we extend the previous observations by looking at mesoscale structural diversity in the presence of atomic scale single steps and using STM to examine smaller domain sizes.…”

Section: Resultsmentioning

confidence: 99%

“…In previous work it has been reported that holes form during the annealing process and that, once formed, these holes cannot fill up through additional silicon deposition and subsequent oxidation. 32 Nonetheless, the change in crystallinity for the bilayer near the hole edge compared to “inland” bilayer ring distributions suggests that structural rearrangements of the silica bilayer near hole boundaries can occur during the hole formation process or may indicate that holes preferentially form in regions with lower local crystallinity. A previous study by Malashevich et al using density functional theory concluded that deviations from the crystalline hexagonal structure would be expected at lower SiO 2 density in bilayer silica due to surface and interfacial tensions.…”

Section: Resultsmentioning

confidence: 99%

Mesoscopic Structures and Coexisting Phases in Silica Films

et al. 2022

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Silica films represent a unique two-dimensional film system, exhibiting both crystalline and vitreous forms. While much scientific work has focused on the atomic-scale features of this film system, mesoscale structures can play an important role for understanding confined space reactions and other applications of silica films. Here, we report on mesoscale structures in silica films grown under ultrahigh vacuum and examined with scanning tunneling microscopy (STM). Silica films can exhibit coexisting phases of monolayer, zigzag, and bilayer structures. Both holes in the film structure and atomic-scale substrate steps are observed to influence these coexisting phases. In particular, film regions bordering holes in silica bilayer films exhibit vitreous character, even in regions where the majority film structure is crystalline. At high coverages mixed zigzag and bilayer phases are observed at step edges, while at lower coverages silica phases with lower silicon densities are observed more prevalently near step edges. The STM images reveal that silica films exhibit rich structural diversity at the mesoscale.

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“…One of the evidences of the deconnexion at the BL coverage is the loss of Si-O-Ru perpendicular vibrations modes as demonstrated by Infrared Reflection Absorption Spectroscopy (IRAS) measurements and confirmed by corresponding DFT calculations. 14,15,24,26,27,43 Binding energy (eV) Intensity (a.u.) In a first experimental setup, a ML-film was elaborated following the preparation method described in the Materials and Methods section.…”

Section: Resultsmentioning

confidence: 99%

Electronic Band Structure of Ultimately Thin Silicon Oxide on Ru(0001)

et al. 2019

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Silicon oxide can be formed in a crystalline form, when prepared on a metallic substrate. It is a candidate support catalyst and possibly the ultimately-thin version of a 1 arXiv:1902.04514v1 [cond-mat.mtrl-sci] 12 Feb 2019 dielectric host material for two-dimensional materials (2D) and heterostructures. We determine the atomic structure and chemical bonding of the ultimately thin version of the oxide, epitaxially grown on Ru(0001). In particular, we establish the existence of two sub-lattices defined by metal-oxygen-silicon bridges involving inequivalent substrate sites. We further discover four electronic bands below Fermi level, at high binding energies, two of them forming a Dirac cone at K point, and two others forming semiflat bands. While the latter two correspond to hybridized states between the oxide and the metal, the former relate to the topmost silicon-oxygen plane, which is not directly coupled to the substrate. Our analysis is based on high resolution X-ray photoelectron spectroscopy, angle-resolved photoemission spectroscopy, scanning tunneling microscopy, and density functional theory calculations.Keywords ultrathin silicon oxide film, monolayer, photoemission spectroscopy, density functional theory calculations, metal-oxide interface Recently, metal-supported crystalline silicon oxide films have been grown as thin as mono-

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Preparation of silica films on Ru(0001): A LEEM/PEEM study

Cited by 20 publications

References 40 publications

Energy Level Shifts at the Silica/Ru(0001) Heterojunction Driven by Surface and Interface Dipoles

Energy Level Shifts at the Silica/Ru(0001) Heterojunction Driven by Surface and Interface Dipoles

Mesoscopic Structures and Coexisting Phases in Silica Films

Electronic Band Structure of Ultimately Thin Silicon Oxide on Ru(0001)

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