1,720,975 research outputs found
Characterization and Investigation of NLO Properties of some Selected Electrodeposited Polythiophenes
Full text linkIn this work we study the electronic properties of ClO− doped polythiophenes and discuss the nonlinear optical properties of these organic
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compounds galvanostatically electrodeposited on ITO glasses. The investigation on the electronic properties (band gap, flat band potential)
was performed by means of a non-destructive optical technique, photocurrent spectroscopy (PCS). The investigation on the nonlinear optical
response was carried out by means of second and third harmonic generation (SHG and THG) measurements. In particular, the effect of the
oxidation state of the polymeric films was studied by comparing the NLO response of oxidized and reduced polythiophenes. Reduced poly-
meric films show higher values of the second (χ
h2i) and third (χ
h3i) order nonlinear optical susceptibilitie
Fluorescence Quenching in Hybrid Solar Cells Based on Electrodeposited ZnO
No full textA study about fluorescence phenomena in hybrid donor-acceptor interfaces based on electrodeposited zinc oxide (e-ZnO)
having different architectures is performed. In particular ITO/ZnO/P3HT and ITO/ZnO/P3HT:PCBM are investigated and
their photoluminescence responses are compared with those of ITO/P3HT and ITO/P3HT:PCBM. As expected,
ITO/ZnO/P3HT:PCBM and ITO/P3HT:PCBM present higher exciton quenching than ITO/ZnO/P3HT and ITO/P3HT
respectively. Furthermore, the hybrid configuration ITO/ZnO/P3HT:PCBM displays a higher quenching percentage in a
wider wavelength range than ITO/P3HT:PCBM, indicating a better photo-induced charge separation in e-ZnO based hybrid
devices
Electrochemical growth and physico-chemical characterization in organic medium of Nb2O5 thin films
No full textInvestigations about the energetics and the electrical properties of niobium thin film, electrochemically grown,
were performed in an organic solution of acetonitrile and lithium perchlorate. The study of the energetics of the
Nb O /organic solution interface was performed by means of a non-destructive optical technique, photocurrent
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spectroscopy. By means of this technique, it was possible estimating the value of the flat band potential and
locating conduction and valence band. A more cathodic value of flat band potential in respect with acidic
solution was found in organic medium. From impedance spectra, the electrical circuit that gives best fitting
values is constituted by two resistances in parallel with two constant phase elements and in series with the
resistance of the electrolyte. On considering the exponential coefficient, the constant phase elements model
distorted capacitances
Structural Properties and Temperature Behaviour of Optical Absorption Edge in Polycrystalline ZnO:X (Cu,Ag) Films
No full textSilver- and copper-doped ZnO lms were prepared by radio-frequency magnetron sputtering on glass substrates.
The in uence of dopants content on the structural, morphological properties as well as on evolution of the optical
absorption edge was considered. It has been found that Ag- and Cu-doped ZnO lms are characterized by wurtzite
crystalline structure with the preferred direction of crystalline orientation (002). The sizes of grains within the
lms were found to be dependent on the type of dopant. The temperature evolution of the optical absorption edge
is described by the modi ed Urbach rule that re ects polycrystalline nature of the material. The corresponding
parameters concerning electron (exciton ) phonon interaction, phonon energies and temperature changes of the
band-gap were determined and analysed
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
Influence of Ag, Cu dopants on the second and third optical harmonic generation of ZnO films
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