Structure and dynamics of : a helium atom scattering study

Gerlach, R.; Glebov, Alexei L.; Lange, Gerrit; Toennies, J. P.; Weiß, Helmut

doi:10.1016/0039-6028(95)00270-7

Cited by 55 publications

(38 citation statements)

References 23 publications

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“…The main band at 2151 cm −1 was assigned to the dynamic dipole of perpendicular oriented CO molecules adsorbed on regular terrace sites, while the latter two bands were attributed to the in-phase and out-of-phase vibrational excitation of tilted CO, respectively. This assignment is supported by the fact that only the band at 2132 cm −1 is detected with s-polarized light [16] and is in line with previous interpretations of helium atom scattering (HAS) and LEED experiments, where a c(4 × 2) overlayer was observed [17,18]. The characteristic superstructure as well as the two bands for the in-phase and out-of-phase vibrational excitation disappear at temperatures above 40 K giving evidence for dynamical reordering of the CO layer as well as partial desorption of CO molecules.…”

Section: Methodssupporting

confidence: 73%

CO adsorption on the surface of MgO(001) thin films

Sterrer¹,

Risse²,

Freund³

2006

Applied Catalysis A: General

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We report infrared reflection-absorption and thermal desorption spectra of CO adsorbed at low temperature (30 K) on the surface of MgO(001) thin films. The high similarity of the observed IR bands as compared to data reported for MgO(100) single crystals and sintered MgO particles gives evidence for the identical surface morphology of the different substrates. CO adsorption series taken at constant temperature/ variable pressure, variable temperature/constant pressure, as well as isotope mixing experiments reveal almost no diffusion of CO on MgO(001) at low temperature, but high adsorbate mobility at slightly elevated temperature.

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Section: Methodssupporting

confidence: 73%

CO adsorption on the surface of MgO(001) thin films

Sterrer¹,

Risse²,

Freund³

2006

Applied Catalysis A: General

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“…Angle-resolved photoelectron spectra M' ] support a case in which the CO molecule lies flat on the surface, and the lone pairs of electrons on carbon (5n) and on oxygen (40) are involved in the bond. This is further supported by the shifting of the ionization energies of the appropriate states.[".…”

Section: Reviewsmentioning

confidence: 96%

Adsorption of Gases on Complex Solid Surfaces

Freund

1997

Angew. Chem. Int. Ed. Engl.

271

170

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During the last thirty years the research field of surface science with its various disciplines has progressively played a more and more important role in the field of catalysis. The main focus of attention for a long time was research on metal surfaces, on which, in time, the whole spectrum of developed surface analytical methods was applied. This led to a better understanding of the mechanisms of catalytic reactions, such as the synthesis of ammonia and the oxidation of CO, especially through the work of Gerhard Ertl.",21 In contrast to clean metal surfaces, surfaces of real catalysts arc complex entities, the structures of which can have a strong influence on the processes occurring on the surface. Thus, it seems logical to employ the typical structural characteristics and the morphology of the catalytic surface as guidelines in the investigation of complex model systems. In this review the preparation, and structural and electronic characterization of such model systems will be discussed. Clean surfaces of catalytically active oxides, as well as model systems for dispersed transition metal/support catalysts will be characterized in terms of their morphology and electronic structure as well as their adsorption and reaction capabilities.

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“…This Pauli repulsion balances the electrostatic attractive forces, resulting in rather weak adsorption energies ranging from 10-50 kJ/mol for CO on typical oxide surfaces, which correspond to physisorption or weak chemisorption [48][49][50]. Nevertheless, the adsorbed molecules adopt favored orientations on the surface [51], but, because of the weak interaction, different orientations become possible, as observed for CO on Cr 2 O 3 (0001) [52]. Vibration spectroscopy data also are in line with this picture of adsorbed molecules on oxide surfaces [48,53,54].…”

Section: Adsorption Processmentioning

confidence: 99%

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Weiß

Ranke

2002

Progress in Surface Science

579

610

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Metal-oxide based catalysts are used for many important synthesis reactions in the chemical industry. A better understanding of the catalyst operation can be achieved by studying elemantary reaction steps on well-defined model catalyst systems. For the dehydrogenation of ethylbenzene to styrene in the presence of steam both unpromoted and potassium promoted iron-oxide catalysts are active. Here we review the work done over unpromoted single-crystalline FeO(111), Fe 3 O 4 (111) and α-Fe 2 O 3 (0001) films grown epitaxially on Pt(111) substrates. Their geometric and electronic surface structures were characterized by STM, LEED, electron microscopy and electron spectroscopic techniques. In an integrative approach, the interaction of water, ethylbenzene and styrene with these films was investigated mainly by thermal desorption and photoelectron emission spectroscopy. The adsorptiondesorption energetics and kinetics depend on the oxide surface terminations and are correlated to the electronic structures and acid-base properties of the corresponding oxide phases, which reveal insight into the nature of the active sites and into the catalytic function of semiconducting oxides in general. Catalytic studies, using a batch reactor arrangement at high gas pressures and post reaction surface analysis, showed that only α-Fe 2 O 3 (0001) containing surface defects is catalytically active, whereas Fe 3 O 4 (111) is always inactive. This can be related to the elementary adsorption and desorption properties observed in ultrahigh vacuum, which indicates that the surface chemical properties of the iron-oxide films do not change significantly across the "pressure-gap". A model is proposed according to which the active site involves a regular acidic surface sites and a defect site next to it. The results on metal-oxide surface chemistry also have implications for other fields, such as environmental science, biophysics and chemical sensors.-2 -"2kyEi9FYSQjBVrZxIPQ.FHIAC_WRa02_review.doc", Datum: 19.02.03

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Structure and dynamics of : a helium atom scattering study

Cited by 55 publications

References 23 publications

CO adsorption on the surface of MgO(001) thin films

CO adsorption on the surface of MgO(001) thin films

Adsorption of Gases on Complex Solid Surfaces

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

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