1,721,062 research outputs found
Surface burgers vectors and surface defects
No full textAlthough extended surface defects are often described as dislocations, they are less commonly associated with Burgers vectors. The concept of linear surface dislocations and their associated surface Burgers vectors is defined and discussed in an introductory way and the main properties are summarised. The definition of the Burgers vector differs from that used in the bulk, as a closed path integral is not used. The Burgers vector is a quantity which is conserved, modulo a surface unit vector, and which adds vectorially; and a surface dislocation must form either a closed loop on a surface, or else begin and terminate at a bulk dislocation. The utility of this approach is illustrated by considering a number of applications in real space, in particular imaging with topographic or diffraction contrast, where the concept allows a general means of classifying defects. In diffraction, the surface Burgers vector provides a convenient way of quantifying the effect of defects on peak profiles
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Adsorption of oxygen on Rh(110): a LEED, Auger electron spectroscopy and thermal desorption study
No full textHe beam study of deconstruction and roughening of Au(110)(1 × 2)
No full textThe deconstruction of the Au(110) surface, i.e., the (1 x 2) --> (1 x 1) phase transition, has been studied by He beam scattering. A critical temperature of 700 +/- 5 K is indicated by the temperature dependence of the half-integral diffraction intensities, and the incoherent elastic intensity. Above 700 K the peak width variation is consistent with Ising-like behaviour, where the main contribution to lateral disorder comes from domain walls. It is also demonstrated that the roughening temperature is substantially larger than the deconstruction temperature. The tails of the specular peak decay as a function of parallel momentum according to a power law with exponent - 1.55 +/- 0.1 at 723 K, indicating that the roughening temperature is higher
NEXAFS measurement of the p-symmetry unoccupied states of silver, palladium and palladium silicide
No full textThe density of unoccupied p states of silver, palladium, and palladium silicide has been measured for the first time with high resolution by x-ray absorption at the MIV,V edges. Our results show that the MIV,V-edge spectra yield information for 4d metals similar to that provided by K and LI edge measurement on 3d metals. The densities of states are in agreement with theoretical predictions both in regard to energy and relative intensity. Changes in the palladium MIV,V spectra on silicide formation give the first direct evidence of the role of Pd 5p states in compound formation
The (2 × 2) p2mg to phase transition
No full textAdsorption of half a monolayer of oxygen on the Rh(110) substrate gives a surface with a (2 × 2) p2mg symmetry structure, in which the substrate has a missing row (1 × 2) structure. He-beam scattering measurements show that close to 750 K this surface structure reversibly transforms into a phase of (1 × 2) symmetry. The phase transition has been classified as belonging to the order-disorder type, and falls into the 2D Ising universality class. Above the transition temperature proliferation of antiphase domain boundaries along the [001] direction is observed and discussed
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