1,721,002 research outputs found
Probing the surface magnetic properties via Auger-photoelectron coincidence spectroscopy
No full textAuger-photoelectron coincidence spectroscopy (APECS) via a dichroic effect is a suitable tool to study complex systems such as magnetic thin films and multilayers. We present clear evidence for such a dichroic effect in the MVV Auger line shape of Fe films on Cu(001) measured by angle resolved APECS showing final state spin selectivity (triplet vs. singlet components). Using the Fermi Golden rule and the density functional theory formalism, the Auger spectrum and its angular distributions are computed. For magnetic systems, the spin dependence of the Auger matrix elements allows one to work out the individual multiplet contributions to the Auger spectrum. For an accurate interpretation of experiments we also take into account the valence hole-hole interaction affecting the Auger line shape by the Cini-Sawatzky theory but considering a spin dependent on-site interaction U. The calculated angular distribution, in case of a non-spherical ionized core level (e.g. l=1, m=0), follows a non-trivial behavior in agreement with experiment
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
Copper-phthalocyanine ultra thin films grown onto Al(100) surface investigated by synchrotron radiation
No full textIn this work X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) are employed to study the CuPc/Al(1 0 0)
organic–inorganic interface. The C 1s core level, investigated for three different coverages, shows sharp differences in passing from bulk
to monolayer range CuPc film: in particular the shake-up satellite is not visible in the early stages of adsorption, suggesting a strong
molecule–substrate interaction. XAS at the Cu L3 edge was employed to study the molecular orientation with respect to the substrate. In the
case of a 40Å CuPc film the molecular plane was found to be almost perpendicular to the substrate surface
Step height oscillations during layer-by-layer growth of Pb on Ge(001)
No full textHeteroepitaxial growth of Pb on the Ge(001) surface has been studied by He atom scattering. For low substrate temperatures, Pb is found to grow layer by layer with (111) orientation. A detailed analysis of the specular peak profile as a function of the He wave vector reveals that the step height of the growing monatomic terraces oscillates with the him thickness. This variation, initially as large as +/-15% around the value of the Pb(Ill) bulk interlayer spacing, gradually dampens out after the deposition of a dozen monolayers. This is direct evidence of quantum size effects affecting the interlayer distance of a growing metal film
Structure and electronic properties of Fe nanostructures on MgO(0 0 1)
No full textWe present and discuss X-ray absorption spectroscopy and resonant photoemission measurements on Fe nanostructures self-assembledon MgO(001). For Fe coverages below 1 ML equivalent we measured an increase of the Fe L23 branching ratio and changes in thesplitting, widths and relative intensities of the different final states in the L3M23M23 resonant Auger peak. Scanning tunnelling microscopyindicates that the average lateral dimensions of the self-aggregated structures decrease with decreasing Fe amount, from 12 nm at15 ML nominal Fe amount to 5 nm at 2 ML Fe. This observation allows to interpret the observed changes in the 3d band electronicproperties in terms of the evolution of the Fe local atomic coordination from a bulk-like situation to a configuration where low dimensionalityeffects are significant._ 2007 Elsevier B.V. All rights reserved
L2L3V Coster Kronig decay in Fe, Ni and NiO: the near edge region.
No full textIn this work we deal with the relaxation of the 2p core hole in transition metals via LVV Auger decay, a specific aspect in itself, though contributing a piece of information for a more general understanding of charge redistribution in the final states of both primary photoemission and following de-excitation process. In the past, the analysis of the process was performed mainly by high energy photoemission spectroscopy (PS) experiments, either standard PS [1,2] or coincidence spectroscopy [3,4]. We have carried out a study of the Coster Kronig (CK) decay in Fe, Ni and NiO by PS using synchrotron radiation. In particular, we have measured the branching ratio beta between the direct L2VV and L2L3V-->L-3'VVV CK transitions. P has been determined as a function of the photon energy in the proximity of the L, edges. For all samples 6 becomes independent upon the photon energy already at few eV above threshold. Nonetheless, the asymptotic value is found to be larger in the metals than in the insulator, this reflecting the different localization of the electronic states involved in the cascade process. Capability and limitations of the method used for the quantitative evaluation of 6 are also discussed
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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