1,720,967 research outputs found
Atomistic Models for Plasmonics: from Metal Nanostructures to Molecular Plasmonics
Full text linkThis thesis introduces a family of classical atomistic electromagnetic multiscale models, referred to as ωMM, designed to simulate the optical properties of plasmonic materials with high accuracy and efficiency. Starting from the ωFQ model, originally developed for Drude-like plasmonic materials, the work extends this approach to noble metals by incorporating interband electron transitions. This enables the study of interactions between fully occupied and partially empty electronic states. The research further broadens the models' applicability to multimetallic systems, including bimetallic and alloyed nanostructures, by generalizing their mathematical formulation. Additionally, the ωMM framework has been reformulated to operate in the real-time domain, enabling the investigation of the time-dependent optical behavior of plasmonic materials. Another significant advancement is the development of models capable of simulating plasmonic interactions with non-absorbing and absorbing environments. These extensions facilitate the study of phenomena such as refractive-index-based localized surface plasmon resonance (LSPR) and surface-enhanced Raman scattering (SERS), making the framework applicable to sensors and nanophotonic devices
PROCEDIMENTO IN-SILICO DI IDENTIFICAZIONE DEL DESIGN DI UN SENSORE PLASMONICO NANOSTRUTTURATO
No full textIn silico design of graphene plasmonic hot-spots
No full textWe propose a route for the rational design of engineered graphene-based nanostructures, which feature enormously enhanced electric fields in their proximity. Geometrical arrangements are inspired by nanopatterns allowing single molecule detection on noble metal substrates, and are conceived to take into account experimental feasibility and ease in fabrication processes. The attention is especially focused on enhancement effects occurring close to edge defects and grain boundaries, which are usually present in graphene samples. There, very localized hot-spots are created, with enhancement factors comparable to noble metal substrates, thus potentially paving the way for single molecule detection from graphene-based substrates
The Electric Field Morphology of Plasmonic Picocavities
Full text linkPicocavities are plasmonic nanostructures featuring atomistic defects within subnanometer gaps. Such a unique morphology enables extreme light confinement at subnanometer scales and drives substantial field enhancements with applications from molecular sensing to plasmon-driven catalysis. However, the impact of atomistic defects on the plasmonic field morphology, which ultimately determines light-matter interactions at the nanoscale, remains largely unexplored due to the limitations of traditional theoretical models. Here, we employ the frequency-dependent fluctuating charges and dipoles (ωFQFμ) approach, an atomistic yet computationally efficient method previously validated against time-dependent density functional theory calculations, to reveal the plasmonic field morphology in gold picocavities composed of thousands of atoms. Our results uncover pronounced field inhomogeneities induced by the atomic-scale defects, which may trigger novel effects where electric field gradients are pivotal. Our findings establish the physical foundations for rationalizing experimental observations and guiding the design of next-generation nanophotonic devices with unprecedented control over atomic-scale field confinement
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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