Interaction of hydrogen with solid surfaces

A semi-empirical model to simulate thermodynamic properties of f.c.c. transition metals is proposed. The attractive energy is derived within a second-moment approximation of the tight-binding scheme. The repulsive pairwise interaction is assumed to be of a Born-Mayer type and the parameters of the potential have been adjusted on the bulk modulus, the elastic constants and the cohesive energy. Bulk vibrational properties and defect energies for vacancies, interstitials and surfaces are estimated. Moreover, molecular dynamics simulations with this potential model to evaluate the high-temperature behaviour are presented. In particular, we have calculated the root-mean-square displacement and the thermal expansion as a function of temperature for Cu and Ni. These results allow us to test the anharmonicity of the potential. The agreement with experiment is quite good for low and intermediate temperatures. At high temperatures (T0·65Tm where T m is the melting temperature) the mean-square displacement ...

Thermodynamical and structural properties of f.c.c. transition metals using a simple tight-binding model

Ion beam crystallography of surfaces and interfaces

Scanning tunnelling microscopy (STM) has proved to be a fascinating and powerful technique in the field of surface science. The fact that sets the STM apart from most other surface sensitive techniques is its ability to resolve the structure of surfaces on an atomic scale, that is atom-by-atom, and furthermore its ability to study the dynamics of surface processes. This article presents a survey of recent STM studies of well characterized single crystal metal surfaces under ultra-high vacuum conditions. It particularly addresses STM investigations of clean metal surfaces, adsorbates on metal surfaces, adsorbate-induced restructuring of metal surfaces, chemical reactions on metal surfaces, metal-on-metal growth and finally studies of electron confinement and quantum size effects on metal surfaces.

https://iopscience.iop.org/article/10.1088/0034-4885/59/12/004/pdf

Scanning tunnelling microscopy studies of metal surfaces

The Pt(100) (5 × 20) ⇋ (1 × 1) phase transition: A study by Rutherford backscattering, nuclear microanalysis, LEED and thermal desorption spectroscopy

Temperature hysteresis in the hex⇄(1×1) phase transition in the Pt(100)–CO system has been investigated using Rutherford backscattering spectroscopy, nuclear microanalysis, work function measurements, LEED, and thermal desorption spectroscopy. The onset of the hex→(1×1) transition occurs at an average surface coverage of 0.08±0.05 monolayers while the onset of the (1×1)→hex transition occurs at 0.25±0.05 monolayers. The results are consistent with a recently proposed model for the phase transition.

Absolute coverages and hysteresis phenomena associated with the CO‐induced Pt(100) hex⇄(1×1) phase transition

Surface phases of Ni(110) induced by adsorption of deuterium

Surface relaxation of clean, and hydrogen covered Pt(111)

The structure and composition of a Pt(100) surface have been monitored by Rutherford backscattering (RBS), nuclear microanalysis (NMA), LEED, and work function (Δφ) techniques during temporal oscillations in the rate of CO oxidation. For a Δφ oscillation amplitude of 60 mV, a constant 0.46±0.06×1015 Pt atoms are out of registry with the bulk throughout an oscillation cycle. The maximum fraction of the surface that could be oscillating between the hex and (1×1) phases is thus 8%. The average CO and O coverages during the oscillations are 0.19±0.04 and 0.13±0.03 monolayers, respectively. These results are discussed in terms of a recent model for the temporal oscillations. No oscillations in Δφ have been detected in similar experiments on Pt(111).

J. A. Davies

Papers

Absolute coverages and hysteresis phenomena associated with the CO‐induced Pt(100) hex⇄(1×1) phase transition

Surface phases of Ni(110) induced by adsorption of deuterium

Surface relaxation of clean, and hydrogen covered Pt(111)

Kinetic oscillations in oxidation of CO over Pt(100): A study by Rutherford backscattering, nuclear microanalysis, LEED, and work function techniques