1,721,074 research outputs found
Strong modification of the transport level alignment in organic materials after optical excitation
Full text linkOrganic photovoltaic devices operate by absorbing light and generating current. These two processes are governed by the optical and transport properties of the organic semiconductor. Despite their common microscopic origin—the electronic structure—disclosing their dynamical interplay is far from trivial. Here we address this issue by time-resolved photoemission to directly investigate the correlation between the optical and transport response in organic materials. We reveal that optical generation of non-interacting excitons in a fullerene film results in a substantial redistribution of all transport levels (within 0.4 eV) of the non-excited molecules. As all observed dynamics evolve on identical timescales, we conclude that optical and transport properties are completely interlinked. This finding paves the way for developing novel concepts for transport level engineering on ultrafast time scales that could lead to novel functional optoelectronic devices
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
Investigating the interaction between π-conjugated organic molecules and metal surfaces with photoemission tomography
No full textPhotoemission tomography (PT) is a combined experimental and theoretical technique applied to molecule–metal interfaces which uses angle-resolved photoemission spectroscopy over a wide angular range, while the photoelectron angular distributions in reciprocal space (momentum maps, or called k-maps) are interpreted in terms of the molecular orbital structure of the initial state. This thesis uses PT to investigate various aspects of the interaction between π-conjugated organic molecular adsorbates and metal surfaces: PT was successfully used to identify the exact products of chemical reactions at surfaces and their local bonding. The measured k-maps confirm a modification of the orbital structure of dibromo-bianthracene on Cu(110) in the thermal reaction and the fully hydrogenated bisanthene is found to be the correct reaction intermediate. To decouple molecular adsorbates from the metal substrate, PT was employed to gauge whether charge is transferred through the interface. Oxygen adsorbed on the Cu(100) surface immobilizes the surface electrons in the Cu–O covalent bonds, thus achieving electronic and physical decoupling of perylene-tetracarboxylic-dianhydride as determined by combined results of PT and normal incidence X-ray standing waves. A special example of an electronically inhomogeneous unary molecular layer on a metal surface is showcased in the saturated monolayer of tetracene on Ag(110). With the help of PT, two highest occupied molecular orbital peaks in the photoemission spectra were found, indicating that two molecular species coexist in the tetracene layer. While one molecule remains neutral, another is charged. Finally, we applied PT to study photoelectron angular distributions for highly-hybridized molecule–metal systems, monolayers of p-sexiphenyl, p-quinquephenyl, and pentacene on Cu(110) and on Ag(110), respectively. In k-maps measured for the lowest unoccupied molecular orbital , PT has identified the scattering of either the Shockley surface states or the states around the projected bulk band gap. The scattering vectors can be directly related to reciprocal lattice vectors of the overlayer structure
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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