Effect of adsorbed H atoms on the Fe electronic states of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Fe</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:mn>001</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>film surfaces

Hiura, Satoshi; Ikeuchi, Akira; Shirini, Soraya; Subagyo, Agus; Sueoka, Kazuhisa

doi:10.1103/physrevb.91.205411

Cited by 15 publications

(41 citation statements)

References 43 publications

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“…These are caused by an additional Fe atom being present in the subsurface layer, which again modifies the density of states of the surface atoms. [24,26] Figure 1b shows an STM image of the Fe 3 O 4 (001) surface following exposure to an ultra-pure water drop for 20 minutes. The surface exhibits bright chains with an apparent height of � 2.1 Å covering � 40 % of the surface.…”

Section: Fe 3 O 4 (001): Scanning Tunneling Microscopy and Low Energymentioning

confidence: 99%

Atomic‐Scale Studies of Fe₃O₄(001) and TiO₂(110) Surfaces Following Immersion in CO₂‐Acidified Water

et al. 2020

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Difficulties associated with the integration of liquids into a UHV environment make surface‐science style studies of mineral dissolution particularly challenging. Recently, we developed a novel experimental setup for the UHV‐compatible dosing of ultrapure liquid water and studied its interaction with TiO2 and Fe3O4 surfaces. Herein, we describe a simple approach to vary the pH through the partial pressure of CO2 (pCO2 ) in the surrounding vacuum chamber and use this to study how these surfaces react to an acidic solution. The TiO2(110) surface is unaffected by the acidic solution, except for a small amount of carbonaceous contamination. The Fe3O4(001)‐(2 ×2 )R45° surface begins to dissolve at a pH 4.0–3.9 (pnormalCO2 =0.8–1 bar) and, although it is significantly roughened, the atomic‐scale structure of the Fe3O4(001) surface layer remains visible in scanning tunneling microscopy (STM) images. X‐ray photoelectron spectroscopy (XPS) reveals that the surface is chemically reduced and contains a significant accumulation of bicarbonate (HCO3−) species. These observations are consistent with Fe(II) being extracted by bicarbonate ions, leading to dissolved iron bicarbonate complexes (Fe(HCO3)2), which precipitate onto the surface when the water evaporates.

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Section: Fe 3 O 4 (001): Scanning Tunneling Microscopy and Low Energymentioning

confidence: 99%

Atomic‐Scale Studies of Fe₃O₄(001) and TiO₂(110) Surfaces Following Immersion in CO₂‐Acidified Water

et al. 2020

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“…[13][14][15] Here, hydrogen can bind to two specific sites in the unit cell of the surface reconstruction and switch between them reversibly. 16,17 In the present work, we investigate the switching between these two adjacent sites at elevated temperaturesi.e. where catalytic reactions most often occur.…”

Section: Introductionmentioning

confidence: 99%

Influence of Local Defects on the Dynamics of O–H Bond Breaking and Formation on a Magnetite Surface

et al. 2019

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The transport of H adatoms across oxide supports plays an important role in many catalytic reactions. We investigate the dynamics of H/Fe3O4(001) between 295 and 382 K. By scanning tunneling microscopy at frame rates of up to 19.6 fps, we observe the thermally activated switching of H between two O atoms on neighboring Fe rows. This switching rate changes in proximity to a defect, explained by density functional theory as a distortion in the Fe-O lattice shortening the diffusion path. Quantitative analysis yields an apparent activation barrier of .9 ± . eV on a pristine surface. The present work highlights the importance of local techniques in the study of atomic-scale dynamics at defective surfaces such as oxide supports.

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“…These dI/dV signals may include contributions from the surface Fe B atoms, however all surface Fe B atoms exclusively exhibited an Fe 3+ charge state. 4,9,16,20,24) If the spectra included mainly the surface Fe B LDOS, such a visible difference in the LDOS would not be observed. Therefore, the dI/dV spectra in Fig.…”

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“…More recently, we revealed that the energy-gap value near the Fermi level of the surface Fe B atoms is ∼0.7 eV. 16) Moreover, the (…”

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“…The epitaxially grown Fe 3 O 4 (001) films were prepared on MgO(001) single-crystal substrates by the deposition of Fe in the presence of oxygen. 13,14,16,22) The MgO(001) substrates were cleaned in situ by heating at 573 K for 16 h and were then annealed at 1073 K for 1 h under an oxygen atmosphere (7 × 10 −7 mbar). The Fe deposition was performed using an electron-beam heating evaporator at a substrate temperature of 573 K. During film formation, the oxygen pressure was set in the range 7×10 −7 to 1×10 −6 mbar.…”

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Direct observation of subsurface charge ordering in Fe₃O₄(001) by scanning tunneling microscopy/spectroscopy

Hiura¹,

Ikeuchi²,

Jochi³

et al. 2017

Appl. Phys. Express

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In this study, we characterized Fe 3 O 4 (001) films using scanning tunneling microscopy/spectroscopy (STM/STS). On the film surfaces, individual iron atoms and (√ 2× √ 2)R45 • reconstructed structures were observed by STM. The STS results showed the higher local density of states just below the Fermi level of narrow sections than wide ones of the surface reconstruction perpendicular to the iron rows. Periodical density of states modulations reproducing this electronic structure were clearly observed by the differential tunneling conductance map. These experimental results revealed the presence of subsurface charge ordering of Fe 2+-Fe 2+ and Fe 3+-Fe 3+ dimers, as proposed in previous density functional theory studies.

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Effect of adsorbed H atoms on the Fe electronic states ofFe3O4(001)film surfaces

Cited by 15 publications

References 43 publications

Atomic‐Scale Studies of Fe₃O₄(001) and TiO₂(110) Surfaces Following Immersion in CO₂‐Acidified Water

Atomic‐Scale Studies of Fe₃O₄(001) and TiO₂(110) Surfaces Following Immersion in CO₂‐Acidified Water

Influence of Local Defects on the Dynamics of O–H Bond Breaking and Formation on a Magnetite Surface

Direct observation of subsurface charge ordering in Fe₃O₄(001) by scanning tunneling microscopy/spectroscopy

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Effect of adsorbed H atoms on the Fe electronic states ofFe3O4(001)film surfaces

Cited by 15 publications

References 43 publications

Atomic‐Scale Studies of Fe3O4(001) and TiO2(110) Surfaces Following Immersion in CO2‐Acidified Water

Atomic‐Scale Studies of Fe3O4(001) and TiO2(110) Surfaces Following Immersion in CO2‐Acidified Water

Influence of Local Defects on the Dynamics of O–H Bond Breaking and Formation on a Magnetite Surface

Direct observation of subsurface charge ordering in Fe3O4(001) by scanning tunneling microscopy/spectroscopy

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Product

Resources

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Atomic‐Scale Studies of Fe₃O₄(001) and TiO₂(110) Surfaces Following Immersion in CO₂‐Acidified Water

Atomic‐Scale Studies of Fe₃O₄(001) and TiO₂(110) Surfaces Following Immersion in CO₂‐Acidified Water

Direct observation of subsurface charge ordering in Fe₃O₄(001) by scanning tunneling microscopy/spectroscopy