Boundary structures of the (n×1) added rows of AgO chains on a Ag(110) surface

Taniguchi, Masateru; Tanaka, Ken; Hashizume, Tomihiro; Sakurai, Takeshi

doi:10.1016/0009-2614(92)85438-g

Cited by 33 publications

(5 citation statements)

References 26 publications

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“…Adsorption of oxygen onto the Ag(110) surface induces a reconstruction of the simple ridge and trough structure. Similar reconstructions have been observed to form (2 × 1) oxygen islands on Cu(110). − Scanning tunneling microscopy (STM) studies for the O/Ag(110) system have demonstrated the formation of long −Ag−O− chains parallel to the [001] direction. − Additional STM studies have investigated the growth of these linear chains and concluded that they are the result of an added-row rather than missing-row structure . This structure is depicted in Figure b for the (3 × 1)−O/Ag(110) example.…”

Section: Discussionmentioning

confidence: 63%

Mechanism of Diethyl Ether Formation on Ag(110) and Its Dependence on Coadsorbed Oxygen Species

1999

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The reactions of adlayers consisting of ethyl ligands, ethoxide groups, and oxygen atoms on Ag(110) were investigated using temperature-programmed desorption and high-resolution electron energy-loss spectroscopy. Iodoethane adsorbs dissociatively at 150 K to produce surface-bound ethyl ligands. These species react to form butane, which desorbs at 221 K, diethyl ether (236 K), ethylene (245 K), water (258 K), acetaldehyde (268 K), and ethanol (268 K). To determine the mechanism of formation of diethyl ether (the most abundant product), several surface mixtures of ethyl and ethoxide species were prepared by adsorption of different coverages of oxygen, iodoethane, and ethanol. While ethyl groups and ethoxides did couple to form diethyl ether in some cases, this reaction occurred only in the presence of additional coadsorbed oxygen atoms on the surface. The kinetics of diethyl ether formation are identical for the two reaction channels investigated: ethyl-ethyl-oxygen coupling and ethyl-ethoxide coupling. Therefore, formation of diethyl ether from two ethyl ligands and an oxygen atom appears to involve the sequential reaction of these species to first form an ethoxide, followed by coupling of the ethoxide with an ethyl group in the presence of additional oxygen atoms. This pathway was confirmed by experiments in which 13 C-labeled ethoxides and unlabeled ethyl groups were deposited on the surface in the presence of oxygen; the product ethers contained either zero or one labeled ligands. The requirement of coadsorbed oxygen atoms for ether synthesis by alkyl-alkoxide coupling is reminiscent of the need for subsurface oxygen in the silver-catalyzed formation of ethylene oxide (a cyclic ether) from ethylene.

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Section: Discussionmentioning

confidence: 63%

Mechanism of Diethyl Ether Formation on Ag(110) and Its Dependence on Coadsorbed Oxygen Species

1999

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“…21 As will be seen below, this is actually the primary building block involved for the energetically favorable structures involving higher oxygen concentrations as well as in silver(I) oxide, Ag 2 O. In addition, oxygen adsorption on Ag(110) with (n×1) reconstructions 46 involve a similar O-Ag-O configuration. The proposed atomic geometry for the (4 × 4)-O/Ag(111) phase 32,33 bears a very close resemblance to the identified low energy (O fcc /O tetra−I ) θ=0.50 structure.…”

Section: B Atomic Structure and Electronic Propertiesmentioning

confidence: 96%

Subsurface oxygen and surface oxide formation at Ag(111): A density-functional theory investigation

2003

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To help provide insight into the remarkable catalytic behavior of the oxygen/silver system for heterogeneous oxidation reactions, purely sub-surface oxygen, and structures involving both on-surface and sub-surface oxygen, as well as oxide-like structures at the Ag(111) surface have been studied for a wide range of coverages and adsorption sites using density-functional theory. Adsorption on the surface in fcc sites is energetically favorable for low coverages, while for higher coverage a thin surface-oxide structure is energetically favorable. This structure has been proposed to correspond to the experimentally observed (4 × 4) phase. With increasing O concentrations, thicker oxide-like structures resembling compressed Ag2O(111) surfaces are energetically favored. Due to the relatively low thermal stability of these structures, and the very low sticking probability of O2 at Ag (111), their formation and observation may require the use of atomic oxygen (or ozone, O3) and low temperatures. We also investigate diffusion of O into the sub-surface region at low coverage (0.11 ML), and the effect of surface Ag vacancies in the adsorption of atomic oxygen and ozone-like species. The present studies, together with our earlier investigations of on-surface and surface-substitutional adsorption, provide a comprehensive picture of the behavior and chemical nature of the interaction of oxygen and Ag (111), as well as of the initial stages of oxide formation.

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“…The model for [p(2×1)-O + p(2×3)-N] coexisting at the Ag(110) surface is shown in Figure c. The (−Ag−O−) strings on the clean Ag(110) surface prefer to disperse at low coverage by repulsive interaction, but the (−Ag−O−) strings coexisting with (Ag 2 N) stripes on Ag(110) are compressed by the growth of (Ag 2 N) stripes. Similar compression of the ( n ×1) (−Ag−O−) strings was observed when CO 2 was adsorbed on the surface, where the carbonate species formed along the [001] direction compress the p( n ×1) (−Ag−O−) structure into the p(2×1) structure .…”

Section: Resultsmentioning

confidence: 58%

Selective Photobleaching of (−Ag−O−) Strings on the Ag(110) Surface

et al. 1996

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A p(2×3)-N Ag(110) surface obtained by N+ and/or N2 + ion bombardment gave a desorption peak of N2 at 530 K. When this p(2×3)-N Ag(110) surface was exposed to O2 at room temperature, the LEED pattern showed a combined structure of [p(2×3)-N + p(2×1)-O]. The STM image proved the growth of the (−Ag−O−) and (Ag2N) strings in the [001] and [11̄0] directions, respectively. The TPD spectrum of the combined surface gave the desorption of N2 at 530 K, NO at 490−520 K, and O2 at 600 K. When this [p(2×3)-N + p(2×1)-O] Ag(110) surface was illuminated with a UV light at room temperature, the (−Ag−O−) strings in the STM image were selectively erased although the (Ag2N) underwent little influence, and the LEED pattern changed to the p(2×3)-N structure. The TPD spectrum of the surface after the illumination gave only N2. These results indicate that surface migration of N atoms triggers the reaction between N and N yielding N2 as well as N and O yielding NO on the surface. Selective photobleaching for the combined structure may suggest a feasibility of atomic scale lithography of the surface by using photochemical reactions.

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Boundary structures of the (n×1) added rows of AgO chains on a Ag(110) surface

Cited by 33 publications

References 26 publications

Mechanism of Diethyl Ether Formation on Ag(110) and Its Dependence on Coadsorbed Oxygen Species

Mechanism of Diethyl Ether Formation on Ag(110) and Its Dependence on Coadsorbed Oxygen Species

Subsurface oxygen and surface oxide formation at Ag(111): A density-functional theory investigation

Selective Photobleaching of (−Ag−O−) Strings on the Ag(110) Surface

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