1,721,013 research outputs found
Tuning Both Bandedge Exciton Dynamics and Energy Transfer Dynamics in Mn-Doped QDs via Doping of Ag Co-Dopants
No full textDoping in colloidal semiconductor nanocrystals (NCs) is an attractive approach for giving new functionalities which come from enhanced interactions between strongly quantum confined band-edge exciton wavefunction and dopant ions. However, fundamental analyses on doped NCs such as precise location and site(interstitial/substitutional) of dopants and correlations between co-dopants were rarely reported because of physical complexity of the system. Here we investigated role of Ag co- dopants in Mn-doped NCs through spectroscopic approaches. Through sophisticated and multi-step, cation exchange and shell overcoating processes, we successfully synthesized co-doped NCs with well-defined doping depth and dopant concentration. With different doping concentration of Ag ions, two completely different trends arise in intensity changes of both band-edge photoluminescence (PL) and Mn dopant sensitized phosphorescence. We also figured out that they are also affected by relative distribution between Mn and Ag ions which shows possibility of sensitive tuning of branching between band-edge dynamics and energy transfer dynamics.1
Colloidal Synthesis of Shape-Controlled Cs2NaBiX6 (X = Cl, Br) Double Perovskite Nanocrystals
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Colloidal Synthesis of Lead-Free Silver Indium Double-Perovskite Cs2AgInCl6 Nanocrystals and Their Doping with Lanthanide Ions
No full textRecently, lead halide perovskite (LHP) materials have shown potential for many optoelectronic applications. However, the structural instability and toxicity concerns necessitated robust and heavy-metal-free alternatives. We report a synthetic route to Cs2AgInCl6 double-perovskite nanocrystals (DP NCs) that have the crystal structure replacing two lead ions in LHP by a pair of silver and indium ions. Cubic-shaped Cs2AgInCl6 DP NCs were obtained with a narrow size distribution, which showed superior stability against moisture that rivaled core-shell-structured CdS/ZnS NCs. Cs2AgInCl6 DP NCs showed discrete optical properties: (i) multiple absorbing states that resolved the parity-forbidden band-edge transition at 3.33 eV and next-following higher order parity-allowed transition at 4.88 eV and (ii) multiple emission states that consisted of the band edge emission at 350 nm and emissions from defective states that peaked at 395 nm. The synthetic route was further exploited for isovalent doping with lanthanide ions, which yielded Yb-doped, Er-doped, and Yb/Er-codoped Cs2AgInCl6 DP NCs. The characteristic f-f transition emissions were observed in infrared at 996 nm for Yb3+ and at 1537 nm for Er3+ dopants.11Nsciescopu
Correction to “Ultrafast Cation Exchange in Supra-Quantum Dots through Nanoporous Internal Structure”
No full textThe author list should be “Hyunmi Doh, Juwon Park, Junhwa Lee, Jiwon Bang, Sanghwa Jeong, Wonseok Lee, Ho Jin, and Sungjee Kim”, with an addition of a co-author, Junhwa Lee. Hyunmi Doh, Juwon Park, and Junhwa Lee contributed equally to this work. This change was agreed to by all authors and is reflected in the authorship of this correction.11Nsciescopu
Ligand Exchange Strategies toward Bright and Stable Ag2S Nanocrystals with Ag-rich, S-rich and Stoichiometric Surface Stoichiometry
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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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