[en] The system W(110) p(2 X 1)-O is studied. A bond stretching and bending model which predicts that the ordering of the absorbed oxygen reconstructs the W(110) surface, is developed. The magnitude of the lateral displacement is 0.076 A. The implications of the model in the formation of the (2 X 1) overlayer structure are also examined. (Auth.)

[en] The potentialities of LEED rotation diagrams at large angles of incidence are examined for surface structure determination. From a comparison of relativistic model calculations for the (00) beam from unreconstructed W(001) to experimental results it is found that the structure of the rotation diagrams is essentially determined by strong intralayer scattering within the first atomic layer, whereas peak intensities in rotation diagrams depend strongly on the distance to the adjacent layers. By means of a simple criterion based on the comparison of theoretical and experimental peak intensity ratios, the top layer contraction is determined to be 5.5% +- 1.5%. The influence of the parameters entering the calculations and of the experimental uncertainties on the validity of this result are discussed. (Auth.)

[en] The evolution of a profile formed by a flat and by a curved surface is examined; it is shown that surface and volume diffusion cooperate in such a way as to favour accumulations of ions with different signs on profile faces. (author)

No abstract available

[en] The present theory of scattering of atoms in three dimensions by a stationary sinusoidal hard-wall surface with one-dimensional periodicity is discussed, and the first calculations of diffractive scattering by a periodic surface with arbitrary orientation are presented. Application is made to the system He-W(112), and two closely-related experimental tests of the theory are proposed. Effects of a gas-surface attractive potential are briefly discussed. (Auth.)

[en] In an electron diffraction pattern divided into Laue zones, the first ring of reflections outside the zero-order Laue zone is called the first-order Laue zone. This applies even when the value of N = hu+kv+lw for the zone is greater than one

No abstract available

[en] A high resolution energy dispersion analysis of the electron loss spectra (ELS) from a W(001) surface has been done with a specular reflexion geometry. The non-dispersive ELS correlates well with a combination of the bulk and surface loss functions determined from recent optical data whereas the dispersive ELS showed significant differences. Multiple plasmon losses were demonstrated while for the interband losses a momentum selection methods has been demonstrated to separate scattering in the surface region from that in the bulk. (Auth.)

[en] Three types of etch pit were observed on single crystals and bicrystals of niobium. The relationship between the shape of the pits and the orientation of the etching surface was established and discussed on the basis of the surface energy concept. It was demonstrated that misorientations of tilt boundaries can be determined in bicrystals using the etch pit technique. (Auth.)

[en] Short note. 1 ref