Local geometrical structure of a Co-adsorption phase on Al(111): atop bonding due to chemical heterogeneity

Scragg, G.; Kerkar, M.; Ettema, A.R.H.F.; Woodruff, D.P.; Cowie, Bruce C. C.; Daïmellah, A.; Turton, S.; Jones, Robert G.

doi:10.1016/0039-6028(95)00095-x

Cited by 16 publications

(4 citation statements)

References 18 publications

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“…The range of adsorbates studied on metal surfaces is quite different from that on semiconductors and reflects differences in the underlying scientific motivation. For example, investigations of Na and O coadsorption on Al (111) [202,203] were motivated by a desire to understand the effect of alkali adatoms in promoting oxidation of this surface. On the other hand, there have been a number of structure determinations of pure alkali metals on metals, Al(111)/Na [177,204], Al (111)/Rb [177,205], Cu(110)/Rb [206], Cu(111)/Rb [207,208], Fe(100)/K [209], Fe(110)/K [210], motivated by a desire to understand these 'simple' chemisorption systems; interest was further fuelled by the surprising finding on Al (111) that alkali atoms may occupy atop sites, or even occupy substitutional sites to form surface alloy layers, despite these metals being immiscible in the bulk.…”

Section: Adsorbed Layers On Metalsmentioning

confidence: 99%

Surface structure determination using x-ray standing waves

Woodruff¹

2005

Rep. Prog. Phys.

194

237

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The technique of x-ray standing waves as a means of structure determination is reviewed with special emphasis on its application to the investigation of adsorbed atoms and molecules at well-characterized single crystal surfaces in ultra-high vacuum. Topics covered include: the physical principles of the method and the underlying theory; methods of detection of the x-ray absorption and their relative merits; the specific advantages of photoelectron detection together with a description of the modified method of data analysis and its underlying physical basis (required to account for non-dipolar angular effects in the photoemission process); some practical issues of data analysis and interpretation including recent developments in the use of structural 'imaging' by direct inversion of the measured structural parameters. A broad survey of applications is included covering atomic and molecular adsorbates on semiconductors and metals as well as the use of the technique to obtain site-specific electronic structure information. Some comments on likely future developments and applications are given.

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Section: Adsorbed Layers On Metalsmentioning

confidence: 99%

Surface structure determination using x-ray standing waves

Woodruff¹

2005

Rep. Prog. Phys.

194

237

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“…In other words, the ( √ 3 × √ 3)R30 • structure is an ordered structure in which both the O atoms and the K atoms participate in the ordering. Such cooperative structures have been observed in other systems and some of their geometries have been determined [4,5,7]. However, a cooperative structure would suggest that there should be a constant or preferred K:O stoichiometry, which is not observed.…”

Section: The Medium-oxygen-coverage Regimementioning

confidence: 84%

“…Spectroscopic studies of this system have been conducted on various substrates over the years in order to address the electronic, vibrational and bonding properties. However, the structural aspects of these coadsorption systems have remained largely unexplored until very recently [4][5][6][7][8][9][10]. Structural information is clearly a key input for understanding the chemical and electronic properties for these systems.…”

Section: Introductionmentioning

confidence: 99%

A low-energy electron diffraction study of potassium - oxygen coadsorption phases on Ni(111)

Li¹,

Diehl²

1997

J. Phys.: Condens. Matter

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The coadsorption of potassium and oxygen on a Ni(111) surface has been studied by low-energy electron diffraction (LEED). The initial potassium-induced structures on the bare and the oxygen-monolayer-covered surface exhibit similar LEED ring patterns, which may be attributed to the strong dipole - dipole repulsive interaction in both cases. On the other hand, a small amount of pre-adsorbed oxygen (θ0<0.1) prevents the formation of the potassium ring phase, suggesting an attractive K - O interaction. Once all of the pre-adsorbed oxygen is attached to the potassium adatoms, further potassium adsorption produces the same phases as on the oxygen-free surface. For intermediate O precoverages, a gradual structural transformation from a p(2 × 2) to a phase is observed upon K adsorption. Potassium reduces the critical oxygen coverage for the completion of this phase transformation, suggesting that (disordered) K mixes in the O layer. At higher O precoverages, coadsorption results in a new c(4 × 2) ordered phase in a structure which probably involves both K and O.

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“…Although there have been extensive studies of the influence of the role of adsorbed alkali metals on molecular dissociation and reaction rates (e.g. [1]) and a few related structural studies, notably of CO/alkali [2][3][4] and O/alkali [5][6][7] coadsorption, there appear to be few studies of alkali and halogen coadsorption. Some exceptions include K/Cl coadsorption on Ag(100) [8], RbCl deposition on Si(100) and W(110) [9], Na/Br coadsorption on WSe 2 (0001) [10] and Cs/Cl coadsorption on Si(100) [11].…”

Section: Introductionmentioning

confidence: 99%

Structural study of Rb and Cl coadsorption on Cu(111): a case of overlayer compound formation

Lüdecke

Skordas

Jackson

et al. 1997

J. Phys.: Condens. Matter

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A structural study of the adsorption of Rb on a Cu(111)( √ 3 × √ 3)R30 • -Cl surface has been conducted using normal-incidence x-ray standing-wavefield absorption at both the Cl and Rb surface atoms. The results indicate reaction of the coadsorbates to form an overlayer of approximately 1.2 ML of RbCl(100) which is essentially incommensurate with the substrate. The RbCl-Cu outermost layer spacing is similar to that seen for pure Rb adsorption on Cu(111). This RbCl layer is spread over the surface and not agglomerated into thicker islands. The results are consistent with prior characterization of the system by Auger electron spectroscopy and temperature-programmed desorption, and with STM studies of NaCl deposition on Al(111).

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Local geometrical structure of a Co-adsorption phase on Al(111): atop bonding due to chemical heterogeneity

Cited by 16 publications

References 18 publications

Surface structure determination using x-ray standing waves

Surface structure determination using x-ray standing waves

A low-energy electron diffraction study of potassium - oxygen coadsorption phases on Ni(111)

Structural study of Rb and Cl coadsorption on Cu(111): a case of overlayer compound formation

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