1,721,045 research outputs found
Annealing of CVD un-doped diamond: a photoemission investigation
No full textThe temperature evolution of the surface region of an undoped chemical vapour deposited (CVD) diamond film is characterized via UV and X-ray induced photoemission. Methods are proposed to diagnose and to overcome possible electrostatic charging problems connected with the poor conductivity of the film. The position of the relevant energy levels is measured and the transition from a negative to a positive electron affinity surface is observed. For the bare diamond surface, an electron affinity χ = 0.4 eV is derived while the film conductivity is shown to decrease on going from the surface towards the bul
H content determination at the (100) surface of homoepitaxial diamond by Elastic Peak Electron Spectroscopy
No full textElastic Peak Electron Spectroscopy (EPES) is used to characterize the H termination of the (1 0 0) diamond surface. Two specific features of the technique make this possible, namely surface sensitivity and the ability to directly detect H. An approach to quantify the H content for the particular spatial distribution involved here is discussed and a measure of H surface coverage is given
Temperature evolution of the surface region of CVD diamond: an electron spectroscopy study
No full textAn electron spectroscopic investigation (photoemission and X-ray induced Auger emission) of the near surface region of undoped CVD polycrystalline diamond is presented. The focus is on compositional and structural changes brought about by desorption processes (either photon or thermally induced) and on the associated changes in the material's properties. Photon and low temperature induced desorption of O containing species, resulting in a clean H terminated diamond surface, is found to decrease the diamond surface conductivity (SC) and to lower the vacuum energy. Electron emission is highly favoured from such a surface, as witnessed by its negative electron affinity (NEA). H desorption at T approximate to 900degreesC leads to surface reconstruction and causes both the vacuum energy to rise and the electron energy levels to bend downwards. As a result, the diamond electron affinity is driven from negative to positive. At T = 1050degreesC, the first stages of a graphitization process that propagates from the surface inwards are revealed by an increasing conductivity in the film surface region, though still not by the development of graphitic features in the spectra
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
- …
