Surface structure of semiconducting ruthenium pyrite (RuS2) investigated by LEED and STM

Colell, H.; Bronold, M.; Fiechter, S.; Tributsch, H.

doi:10.1016/0039-6028(94)90613-0

Cited by 16 publications

(10 citation statements)

References 14 publications

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“…The surface energy of the crenellated {100} surface decreases more upon relaxation (3.67-3.19 J m -2 ) than the planar surface (1.30-1.23 J m -2 ) (Table 3) but, due to the creation of step edges, it remains much higher and hence the crenellated surface is far less stable than the planar {100} surface. This agrees with experimental findings, e.g., scanning tunneling microscopy (STM) and LEED studies of {100} surfaces of FeS 2 8 and isostructural RuS 2 , 25 where the {100} surface is found to show negligible relaxation from bulktermination and no essential reconstruction. The planar {110} surface is less stable than the planar {100} surface and does not show much relaxation from bulktermination (γ unrel ) 2.58 versus γ rel ) 2.36 J m -2 ).…”

Section: Resultssupporting

confidence: 91%

Modeling the Surface Structure and Reactivity of Pyrite: Introducing a Potential Model for FeS₂

et al. 2000

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Atomistic simulation techniques are used to investigate the surface structure, stability and reactivity of pyrite. We introduce a potential model for FeS2 which reproduces experimental structural parameters, elastic constants and hydration energies of pyrite. We modeled the {100}, {110}, and {111} surfaces of pyrite and calculated the {100} surface to be the most stable and to show little surface relaxation, in agreement with experiment. The surfaces were hydrated by associative adsorption of water molecules which stabilized all three surfaces, especially the unstable {111} surface. The calculated adsorption energy of −47 kJ mol-1 for water on the {100} surface agrees well with an adsorption energy of −42 kJ mol-1, determined for the stoichiometric (100) surface by temperature-programmed desorption. Adsorption of water molecules at surface sites of lower coordination (four- or three- coordinated) showed increased reactivity of these sites. We calculated an increase in adsorption energy of 50−60 kJ mol-1 per loss of bond. We next created stepped {100} planes in order to model a more realistic {100} surface with one-dimensional defects. Four different steps were investigated in two orthogonal directions. Because of the asymmetry of the sulfur dimers, the geometry of the dimers on the edge showed the dimers either leaning forward (F-steps) or backward (B-steps) with respect to the {100} terrace. We used water molecules as a probe of the reactivity of the different surface sites. Corresponding adsorption sites (terrace, edge or below the step) on the F- and B-steps were found to have different reactivities toward water due to the different adsorption modes of the probe molecule. On the B-steps the increased reactivity of the low-coordinated edge iron atom toward water (approximately −70 kJ mol-1) was outweighed by the network of interactions of the water molecule to atoms on terrace and step wall in the position below the step (−91 kJ mol-1). On the F-steps the four-coordinated edge site was calculated to be the most reactive adsorption site.

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Section: Resultssupporting

confidence: 91%

Modeling the Surface Structure and Reactivity of Pyrite: Introducing a Potential Model for FeS₂

et al. 2000

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“…The calculation of the Hellmann−Feynman forces acting on the atoms and a standard BFGS technique allows the structural optimization. In agreement with experiment and previous calculations, , the relaxation obtained for R5 and R3 is negligible leaving to the Ru−S bonds with almost the same value that they have in the bulk 21 (Ru−S bond distance = 2.356 Å). In fact, the study of the reduction process of RuS 2 has shown that near 50% of the sulfur content can be removed from the surface without perceptible structural modification of the surface .…”

Section: Surface Modelssupporting

confidence: 91%

Adsorption of Thiophene on the RuS₂(100) and (111) Surfaces: A Laplacian of the Electronic Charge Density Study

et al. 2002

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To study the effect of the surface Ru sulfur coordination number and of the surface S-H and Ru-H species into the thiophene adsorption on RuS 2 , a topologic study of the Laplacian of the electronic density of selected (100) and ( 111) surfaces was carried out. It was found that a nonbonded local charge concentration on the S atom of the thiophene interacts with a local minimum on the outermost Ru atoms of the surfaces. This interaction is strongly affected by a nonbonded local charge concentration located on the outermost S atoms of the surface. Both interactions combine in such way that the strength of the thiophene adsorption on the unhydrogenated surfaces shows small changes. The main role of the S-H bond is to move away the surface sulfur local charge concentrations from the Ru atoms while the Ru-H species favors the hydride attacks to a local minimum located at the C R of the thiophene molecule.

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“…The application of near-field microscopy techniques, namely, scanning tunneling microscopy (STM) and atomic force microscopy (AFM), to surface structures has allowed real space analysis with atomic scale lateral resolution. STM and electrochemical applications of this (ECSTM) have been applied to study the inorganic crystal surfaces of graphite {0001} and metal sulfides, including the surface of molybdenite (MoS 2 ) {0001}, , iron pyrite (FeS 2 ) {100}, , {101}, , ruthenium pyrite (RuS 2 ) {100}, and galena (PbS 2 ) {100}, , {001}. − These studies suggest that STM examination of prebiotically relevant minerals and their interactions with organic compounds may provide some evidence for processes that lead to the emergence of life.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembly at the Prebiotic Solid−Liquid Interface: Structures of Self-Assembled Monolayers of Adenine and Guanine Bases Formed on Inorganic Surfaces

1998

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Previously proposed models of monolayers of adenine and guanine, based on scanning tunneling microscopy and atomic force microscopy images, have been critically examined. We have applied molecular mechanics computer simulations to these models and, where appropriate, examined additional scanning tunneling microscopy data. These findings support the proposed adenine structure based on low-energy diffraction analysis and molecular mechanics but indicate that the structure of the guanine monolayer on graphite is different from those previously proposed. These findings indicate that the energy-minimized adsorbate stuctures of both adenine and guanine form a similar molecular configuration on both graphite and molybdenum disulfide surfaces. It is speculated that the formation of these structures may have had some prebiotic relevance.

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Surface structure of semiconducting ruthenium pyrite (RuS2) investigated by LEED and STM

Cited by 16 publications

References 14 publications

Modeling the Surface Structure and Reactivity of Pyrite: Introducing a Potential Model for FeS₂

Modeling the Surface Structure and Reactivity of Pyrite: Introducing a Potential Model for FeS₂

Adsorption of Thiophene on the RuS₂(100) and (111) Surfaces: A Laplacian of the Electronic Charge Density Study

Self-Assembly at the Prebiotic Solid−Liquid Interface: Structures of Self-Assembled Monolayers of Adenine and Guanine Bases Formed on Inorganic Surfaces

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Surface structure of semiconducting ruthenium pyrite (RuS2) investigated by LEED and STM

Cited by 16 publications

References 14 publications

Modeling the Surface Structure and Reactivity of Pyrite: Introducing a Potential Model for FeS2

Modeling the Surface Structure and Reactivity of Pyrite: Introducing a Potential Model for FeS2

Adsorption of Thiophene on the RuS2(100) and (111) Surfaces: A Laplacian of the Electronic Charge Density Study

Self-Assembly at the Prebiotic Solid−Liquid Interface: Structures of Self-Assembled Monolayers of Adenine and Guanine Bases Formed on Inorganic Surfaces

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Modeling the Surface Structure and Reactivity of Pyrite: Introducing a Potential Model for FeS₂

Modeling the Surface Structure and Reactivity of Pyrite: Introducing a Potential Model for FeS₂

Adsorption of Thiophene on the RuS₂(100) and (111) Surfaces: A Laplacian of the Electronic Charge Density Study