New Directions for Atomic Steps: Step Alignment by Grazing Incident Ion Beams on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>TiO</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>110</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math>

Luttrell, Tim; Li, Weikun; Gong, Xue‐Qing; Batzill, Matthias

doi:10.1103/physrevlett.102.166103

Cited by 31 publications

(27 citation statements)

References 31 publications

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“…However, the images determined experimentally often show only the states that are energetically stable enough at measurement conditions, and the origin of the formation of such states and even the detailed atomic configurations of corresponding images are often unclear. Remarkably, firstprinciple calculations based on density functional theory (DFT) can provide valuable insights into these processes, thus the characteristic surface images can be better interpreted [6,7].…”

Section: Introductionmentioning

confidence: 99%

Unique adsorption behaviors of carboxylic acids at rutile TiO2(110)

Gong

2015

Surface Science

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Section: Introductionmentioning

confidence: 99%

Unique adsorption behaviors of carboxylic acids at rutile TiO2(110)

Gong

2015

Surface Science

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“…4−7 Surface steps can be active sites for catalysis 8,9 and are preferential sites for the adsorption of adatoms and molecules 10 and nucleation for metal nanoclusters. 11,12 Steps on metal and semiconductor surfaces have been investigated extensively in experiment and theory, 13,14 but structurally and electronically complex oxide surfaces have received less attention.…”

Section: ■ Introductionmentioning

confidence: 99%

Energetics of Rutile TiO₂ Vicinal Surfaces with ⟨001⟩ Steps from the Energy Density Method

Lee

Trinkle²

2015

J. Phys. Chem. C

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Rutile TiO 2 vicinal surfaces with ⟨001⟩ steps are investigated using the energy density method (EDM) based on density functional theory. In this approach, EDM provides the energy for each atom so that we can determine the stability of different step configurations correctly. Even though the energy variation due to the step is localized around the step edge, the step−step interaction is long ranged. The finite-size effect in the step−step interaction is identified using EDM. The oxygen vacancy at the step edge explains the atomic structure of the step observed by STM. ■ INTRODUCTIONThe geometries and energetics of steps on surfaces play a crucial role in a wide range of surface phenomena.Step edges influence surface morphologies and have been observed to cause surface reconstructions 1−3 and affect the shapes of islands on the surfaces. 4−7 Surface steps can be active sites for catalysis 8,9 and are preferential sites for the adsorption of adatoms and molecules 10 and nucleation for metal nanoclusters. 11,12 Steps on metal and semiconductor surfaces have been investigated extensively in experiment and theory, 13,14 but structurally and electronically complex oxide surfaces have received less attention. Recent studies have computed the steps on MgO, 15 CeO 2 , 16 SrTiO 3 , 17 and TiO 2 surfaces 3,6−9,18,19 due to their importance in catalytic applications. In particular, rutile TiO 2 step structures and energies have been the subject of both experimental and computational studies to elucidate their role in the high catalytic activity of TiO 2 .Scanning tunneling microscopy (STM) studies observed three different types of monatomic height steps on the TiO 2 (110) surfaces whose step edges are running along either [001], [111], or [110] directions. 4,10,20,21 The ⟨001⟩ and ⟨111⟩ steps form during annealing on sputtered surfaces, and ⟨111⟩ steps occurring at low annealing temperatures and ⟨001⟩ steps become favorable at high annealing temperatures. 4,20 The ⟨110⟩ steps are metastable and are formed by ion beam injection. 10 The reconstructed ⟨111⟩ step edges are reported with strand structures and oxygen vacancies. 3,8,9,22 Diebold et al. characterized the atomic structure of ⟨001⟩ steps using STM. 21 They observed two different types of ⟨001⟩ steps: one which is terminated with bridging oxygen atoms ⟨001⟩ O and the other is a reconstructed ⟨001⟩ step with exposed 5-fold titanium atoms ⟨001⟩ Ti . They reported specific (1 × 4) reconstruction on the ⟨001⟩ Ti step; however, other experimental studies show that the ⟨001⟩ step edges are rough and undercoordinated. 3,22 Density functional theory (DFT) calculates the energies of specific atomic configurations and determines their relative stability. Previous DFT studies found that the ⟨111⟩ step with reconstructed step edge is the most stable step configuration on TiO 2 vicinal surfaces. 6,7,19 The ⟨110⟩ step has the highest step energy even after it reconstructs, 7 and the ⟨001⟩ step has only two stable structures that are ⟨001⟩ O and ⟨001⟩ Ti steps. 19 Recently, Hardcast...

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“…These regular patterns have a significant potential for applications ranging from the modification of wetting and optical reflectivity, via patterned adsorption to data storage [4]. Evidently, the understanding of pattern formation requires a detailed, atomistic knowledge of single ionsurface interaction, and, in particular, of damage formation and healing.Upon grazing incidence, highly regular ripple patterns with ridges aligned with the ion beam direction evolve on metals [5,6], oxides [7], and alkali halides [8]. It was soon realized that for the formation and regularity of these patterns subsurface channeling should be of decisive importance [6,8].…”

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“…Upon grazing incidence, highly regular ripple patterns with ridges aligned with the ion beam direction evolve on metals [5,6], oxides [7], and alkali halides [8]. It was soon realized that for the formation and regularity of these patterns subsurface channeling should be of decisive importance [6,8].…”

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Trails of Kilovolt Ions Created by Subsurface Channeling

et al. 2010

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Using scanning tunneling microscopy, we observe the damage trails produced by keV noble-gas ions incident at glancing angles onto Pt(111). Surface vacancies and adatoms aligned along the ion trajectory constitute the ion trails. Atomistic simulations reveal that these straight trails are produced by nuclear (elastic) collisions with surface layer atoms during subsurface channeling of the projectiles. In a small energy window around 5 keV, Xe þ ions create vacancy grooves that mark the ion trajectory with atomic precision. The asymmetry of the adatom production on the two sides of the projectile path is traced back to the asymmetry of the ion's subsurface channel. DOI: 10.1103/PhysRevLett.104.075501 PACS numbers: 61.80.Jh, 68.37.Ef, 79.20.Ap, 79.20.Rf The interaction of keV ion beams with surfaces has encountered renewed interest recently due to their ability to create regular dot and ripple patterns on the nanoscale [1][2][3]. These regular patterns have a significant potential for applications ranging from the modification of wetting and optical reflectivity, via patterned adsorption to data storage [4]. Evidently, the understanding of pattern formation requires a detailed, atomistic knowledge of single ionsurface interaction, and, in particular, of damage formation and healing.Upon grazing incidence, highly regular ripple patterns with ridges aligned with the ion beam direction evolve on metals [5,6], oxides [7], and alkali halides [8]. It was soon realized that for the formation and regularity of these patterns subsurface channeling should be of decisive importance [6,8]. In subsurface channeling the ion enters the crystal under a small angle with respect to a low index surface (and often a low index direction)-typically at an ascending step-and then moves immediately below the surface layer [9,10]. Like in bulk channeling [11][12][13], the ion is then steered by atomic rows (or planes) along its path, thereby preventing close encounters with atoms. The ion energy loss per unit length is greatly diminished and its range extended.Here we show experiments that visualize for the first time the trajectory of an ion performing subsurface channeling. The channeling particle leaves behind a trail of adatoms and surface vacancies which mark the ion trajectory with atomic precision. Guided by the molecular dynamics (MD) simulations accompanying our experiments we are even able to create a new type of nanostructure on Pt(111) for Xe þ ions of appropriate energy: one-or twoatom-wide continuous rows of vacancies, %50 nm long and aligned along a high symmetry direction.The ion trails of keV ions formed by nuclear (elastic) energy loss are reminiscent of the ion tracks of swift heavy MeV ions which result from electronic (inelastic) energy loss [14]. However, instead of keV= A for swift heavy ions, only eV= A are dissipated in the target by the channeling keV ions. It has to be noted that previously surface images of the impact points of ions with keV kinetic or potential energy were obtained [15][16][17], but not of e...

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New Directions for Atomic Steps: Step Alignment by Grazing Incident Ion Beams onTiO2(110)

Cited by 31 publications

References 31 publications

Unique adsorption behaviors of carboxylic acids at rutile TiO2(110)

Unique adsorption behaviors of carboxylic acids at rutile TiO2(110)

Energetics of Rutile TiO₂ Vicinal Surfaces with ⟨001⟩ Steps from the Energy Density Method

Trails of Kilovolt Ions Created by Subsurface Channeling

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New Directions for Atomic Steps: Step Alignment by Grazing Incident Ion Beams onTiO2(110)

Cited by 31 publications

References 31 publications

Unique adsorption behaviors of carboxylic acids at rutile TiO2(110)

Unique adsorption behaviors of carboxylic acids at rutile TiO2(110)

Energetics of Rutile TiO2 Vicinal Surfaces with ⟨001⟩ Steps from the Energy Density Method

Trails of Kilovolt Ions Created by Subsurface Channeling

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Product

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Energetics of Rutile TiO₂ Vicinal Surfaces with ⟨001⟩ Steps from the Energy Density Method