1,721,002 research outputs found
Scanning tunneling spectroscopy investigation of the (root 3 x root 3)R30 degrees Sn/Si(111) alpha and gamma surfaces
No full textValence electronic properties of porphyrin derivatives
No full textWe present a combined experimental and theoretical investigation of the valence electronic structure of porphyrin-derived molecules. The valence photoemission spectra of the free-base tetraphenylporphyrin and of the octaethylporphyrin molecule were measured using synchrotron radiation and compared with theoretical spectra calculated using the GW method and the density-functional method within the generalized gradient approximation. Only the GW results could reproduce the experimental data. We found that the contribution to the orbital energies due to electronic correlations has the same linear behavior in both molecules, with larger deviations in the vicinity of the HOMO level. This shows the importance of adequate treatment of electronic correlations in these organic systems
EVOLUTION OF THE MISSING-ROW DECONSTRUCTION ON RH(110)
No full textThe transformation of the (1 × 2) Rh (110) missing row non-equilibrium structure to the stable (1 × 1) structure has been studied by He atom scattering. The transformation is found to take place by the formation of islands of the (1 × 1) phase which are elongated in the [10] direction giving rise to a mesh of alternately up and down steps. A numerical simulation, based on an anisotropic classical 2D Ising model, is presented and shows that the experimental data can be interpreted as a spinodal decomposition of a lattice gas
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Interference effects in the Auger decay of the resonantly excited 2p(3/2)(-1)3d state of argon RID G-7348-2011
No full textHigh resolution resonant Auger spectra have been measured at the VUV beam line at ELETTRA, Sincrotrone Trieste, while tuning the photon energy across the 2p(3/2)(-1)3d resonance of argon. A large variation of the branching ratio for decay into the spectator 3p(-2)3d and shakeup 3p(-2)4d channels is observed. The effect has not been seen previously in resonant inner-shell excitation and is attributed to the interference between the direct photoionization process and resonant Auger decay leading to the same final state
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Short-range order in two-dimensional binary alloys
No full textUsing variable-temperature scanning tunneling microscopy, the degree of short-range order of purely two- dimensional (2D) binary alloys on triangular lattices [Sn(1-x)-Si-x, Pb(1-x)-Si-x, and Pb(1-x)-Ge-x, all showing the root3x3 R30 degrees reconstruction onto Si(111) or Ge(111)] has been determined quantitatively via a statistical analysis of the atomic positions. The experimental data, also in comparison with Monte Carlo simulations, generally indicate that an effective nearest-neighbor repulsion between substitutional Si (Ge) adatoms explains with good accuracy the short-range-order features observed. This finding implies the occurrence of an ordered phase of the alloys for x = 0.33 and, in the case of a 1:1 ratio of Sn(Pb) and Si(Ge) adatoms on the surface (x = 0.5), demonstrates that the investigated alloys are very good practical realizations of a frustrated antiferromagnetic 2D Ising system on a triangular lattice. The implications of the observed short-range order for the electronic properties of these alloys (as a function of x) are discussed
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