1,721,039 research outputs found
Optical gaps of dilute α-phase Ag-Cd alloys from thermoreflectance measurements
No full textThe fractional change in reflectivity due to temperature ΔR/R of bulk samples of four silver-cadmium alloys was measured in the energy range (2.2÷4.8) eV. The samples had cadmium concentrations of 1.5, 3.0, 6.5 and 15 at. %. The temperature-induced changes of the imaginary parts of the complex dielectric constant De2 2were calculated by means of an analytical model previously developed by one of the authors. Using the optical gaps at the symmetry pointL as adjustable parameters, we have reconstructed the experimental ΔR/R spectra with good results. This has allowed us to determine with substantially increased accuracy over previous alloy work the dependence of theL′2(E F)−L 1 andL 3−L′2(E F) absorption edges and of theL′2−L 1 critical pointvs. solute concentration. In particular we find for theL′2(E F)−L 1 absorption edge the same slopevs. concentration already determined by Flaten and Stern, but the absolute values are consistently higher by almost 0.5 eV. Also interesting is the behaviour of theL 3 L′2(E F) absorption, edge which shows at first a slight decreasevs. solute concentration which is the opposite of what is predicted by the rigid-band model
Thermoreflectance of Ag single crystals
No full textThermoreflectance measurements of single-crystal Ag have been performed at room temperature in order to solve some discrepancies in the position and attribution of optical gaps, which have arisen in the recent literature. An extension of a previous theoretical model allows a very detailed fit of the experimental data and elucidates completely the origin of optical structures
Temperature dependence of the interband absorption edge of copper
No full textThe optical absorption spectra of bulk copper measured by Pells and Shiga have been fitted by means of a model calculation in the interband edge region. The optical gap and the dipole matrix element of the L3-L'2(EF) transition have been determined as a function of the temperature and a comparison with similar results obtained for silver and gold is presented
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
Versatile low-cost digital lock-in amplifier suitable for multichannel phase-sensitive detection
No full textShift of electronic states at L in α-phase Cu-Zn and Cu-Al alloys
No full textThe variation of the imaginary part of the dielectric constant Delta epsilon 2 obtained by compositional modulation for Cu0.99-Zn0.01 and Cu0.99-Al0.01 has been fitted using a simple theoretical model. Detailed line shape analysis allows accurate determination of the shifts of the Fermi surface and of several of the relevant electronic levels at the point L of the Brillouin zone for both alloys
Electronic structure of dilute α-phase AgCd alloys from thermoreflectance and XPS measurements
No full textThe position of the s, p, and d-like levels (at L) in four different silver—cadmium dilute α-phase alloys is determined with respect to the Fermi level, using thermoreflectance and XPS measurements. The use of an analytical model, previously developed, to fit the thermoreflectance data, allows to determine, with substantially increased accuracy over previous alloy work, the dependence of the relevant optical gaps versus solute concentration. Of particular relevance is the behaviour of the L3L′2(EF) gap which shows at first a slight decrease versus solute concentration. XPS measurements on the same samples are consistent with this behaviour which is the opposite of what is predicted by the rigid band model
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
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