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The influence of rare gas matrix on the electronic levels of isolated atoms
No full textA pseudopotential model is suggested for the calculation of the matrix perturbation on the spectra of isolated atoms. The calculated shifts of the ground state and of the excited state have different signs. The energy of the outer electron of the isolated atom is lowered in the substitutional site. A blue shift for the PS absorption lines of the right magnitude is calculated for Cu, Ag, and Au atoms on substitutional sites in Ar, Kr, and Xe matrices
Isolated noble-metal atoms in a Neon matrix
No full textBy a pseudopotential method, the perturbation of the outer electronic s and p levels of Cu, Ag, and Au atoms by a Ne matrix is calculated. It is concluded that for Cu and Au the trapping site consists of three vacancies. Two sites of three and four vacancies give the two different "triplets" in the absorption spectrum of Ag
Matrix trapping site for H atoms trapped in Ne and Ar
No full textThe optical absorption spectra of H atoms isolated in Ne and Ar matrices are analysed. The first transition is calculated by a pseudopotential method and we can conclude that H atoms are trapped in substitutional sites. The higher excitations can be understood by the exciton formula for the host
Matrix effects on the optical spectra of alkali atoms trapped in Ar, Kr and Xe matrices: a pseudopotential calculations
No full textBy a pseudopotential method the perturbation of the outer electronic s and p levels of Na and K by rare gas matrices is calculated. It is concluded that the stable trapping site consists of four vacancies, except for a substitutional site for Na in Xe. A metastable site of three vacancies gives the ''red triplet'' in the absorption spectrum
Removal of orbital degeneracy of the atomic P state for matrix isolated metal atoms
No full textA theoretical study is made of the matrix effects on the absorption spectra of the noble metal atoms Cu, Ag, and Au isolated in Ar, Kr, and Xe matrices. The matrix influence which is discussed in terms of level shifts and additional crystal field splittings is calculated by a nonlocal pseudopotential method. In order to get a threefold splitting of the P level, we assume an axial symmetry for the metal atom site which is caused by a distorted neighborhood in a fcc matrix. This is the first theoretical investigation of the matrix cage distortion around the impurity. The results show that only small variations of the nearest neighbor distances between isolated atoms and matrix atoms are necessary to account for the observed matrix perturbations
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
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