1,721,107 research outputs found
An extended X-ray absorption fine structure study of Mn ultrathin films grown on Cu(100)
No full textUltrathin Mn ®lms grown at room temperature on Cu(1 0 0) have been studied with extended X-ray absorption ®nestructure (EXAFS) assisted by low energy electron diraction (LEED). At a ®lm coverage H 0:5 monolayers (ML),corresponding to the presence of a c2 2 superstructure in the LEED pattern, we obtained values of the bond lengthand of the eective coordination number which are consistent with the formation of a surface MnCu alloy, in agreementwith previously published results. At increasing coverage the degradation of the LEED pattern with the disappearenceof the spots at H 6 ML and the absence of a clear multishell signal in the EXAFS results point towards a progressivedecrease of long-range crystal order, probably caused by the strain of Mn ®lms growing in a strongly distorted lattice
A Surface Extended X-ray Absorption Fine Structure investigation of Fe islands grown on c(2x2) N/Cu(100) surface
No full textWe present the results of a surface extended X-ray absorption fine structure (SEXAFS) investigation of the growthof Fe islands on the c(2×2) N/Cu(100) surface for different N doses. It is known from scanning tunnelling microscopy(STM) experiments that at subsaturation coverage adsorbed N atoms on Cu(100) form square islands of c(2×2)periodicity and about 5 nm×5 nm in size. These islands can self-organize in regular patterns. From the persistence ofthe c(2×2) low energy electron diffraction patterns obtained for any Fe and N coverage we deduce (in agreementwith previous STM results) that Fe islands grow on surface areas which are not passivated by N atoms. In this studywe estimate that we were able to produce Fe islands thicker than 10 atomic layers, a value higher than that observedusing STM. The first shell analysis of SEXAFS data shows that Fe atoms are arranged in an fcc lattice with tetragonaldistortion, as observed in Fe/Cu(100) films, with the formation of bilayers and/or coalescence in small islands at thelowest coverage studied (one monolayer)
Structure properties of nanostructured Fe films grown on c(2x2)N/Cu(100) self organised surface
No full textThe growth of Fe on the c(2x2)N/Cu(100) surface was studied with XAFS assisted by LEED. Previous STM work had shown that atomic N on Cu(100) forms periodic arrays of c(2x2) N islands with a size of about 5x5 nm channelling the growth of Fe onto the clean Cu areas. From XAFS multishell analysis we describe the growth in terms of fcc phase with strong lattice distortion, deviation from the layer by layer growth, and presence of surface complex phases, some with different geometry. The differences between the Fe growth on the clean and N saturated Cu(100) surface are explained in terms of Fe-N atoms interaction, and we could obtain the adsorption geometry of Fe on N-saturated surface
Spin-Orbit Relativistic Time Dependent Density Functional Calculations of the Metal and Ligand Pre-Edge XAS Intensities of Organotitanium Vomplexes: TiCl4, Ti(η5-C5H5)Cl3, and Ti(η5-C5H5)2Cl2.
No full textTime-dependent density functional theory (TDDFT) coupled to the relativistic two-component zeroth-order regular approximation, both available in the last version of the ADF package, have been successfully used to simulate X-ray absorption spectra of TiCl4, Ti(η5-C5H5)Cl3, and Ti(η5-C5H5)2Cl2 in terms of their oscillator strength distributions. Besides allowing a first principle assignment of Ti 1s, Cl 1s, and Ti 2p (L2,3 edges) core excitation spectra, theoretical outcomes provide a rationale for deviations from the expected L3/L2 branching ratio
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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