Search results for "photo"
showing 10 items of 11789 documents
Engeneering 3D Nanoscale Order in Molecular thin films for organic photovoltaics
2010
Alcohol-Selective Oxidation in Water under Mild Conditions via a Novel Approach to Hybrid Composite Photocatalysts
2015
Abstract The oxidation of alcohols to carbonyl compounds in a clean fashion (i.e., with water as a solvent or under solvent‐free conditions, and using O2 or H2O2 as the primary oxidant) is the subject of considerable research efforts. A new approach for the selective oxidation of soluble aromatic alcohols in water under mild conditions via a novel composite photocatalyst has been developed. The catalyst is synthesized by grafting 4‐(4‐(4‐hydroxyphenylimino)cyclohexa‐2,5dienylideneamino)phenol and silver nanoparticles onto the surface of moderately crystalline titanium dioxide. The titanium dioxide‐based composite was first extensively characterized and then employed in the catalytic oxidati…
Strong field phenomena: Atoms, Molecules, Nanostructures.
Surface modification of poly(ethylene-co-acrylic acid) with amino-functionalized silica nanoparticles
2011
In this work we studied the possibility to achieve a hybrid-surface through the modification, via a facile wet chemical process, of the surface of films of poly(ethylene-co-acrylic acid) (EAA) with amino-modified silica nanoparticles. Films of EAA were preliminarily activated by the introduction of -COCl groups on their surface. Silica nanoparticles were thereafter covalently bound on the polymeric surface as confirmed by FTIR, ATR-FTIR, XPS, NMR and SEM determinations. The nanoparticles formed a multilayer on the film surface and covered almost uniformly the whole film surface. Direct measurements of superficial amino groups by titration allowed us to detect a concentration of about 18 nmo…
Optical and electronic properties of the two-dimensional materials InSe, WSe2 and MoS2
2017
El camp dels materials bidimensionals ha atret recentment l’atenció de la comunitat científica. Les propietats particulars que aquests materials presenten quan el seu espessor és reduït fins l’escala nanomètrica permeten preveure el seu potencial per a aplicacions de recerca, tant fonamental com tecnològica, en una varietat de camps que inclou la catàlisi, l’emmagatzematge d’energia, la detecció, els dispositius optoelectrònics i la informació quàntica. Aquesta tesi presenta l’estudi de les propietats òptiques i electròniques de diferents materials van der Waals bidimensionals: les àmpliament estudiades formes bidimensionals dels dicalcogenurs de metals de transició MoS2 i WSe2, i les menys…
Optoelectronic devices based on caesium lead halide perovskite nanocrystals
2020
Tradicionalmente, la implementación de materiales activos en circuitos fotónicos integrados se ha basado en la utilización de semiconductores III-V y vidrios y materiales ferroeléctricos dopados con iones de tierras raras. Sin embargo, en la actualidad existe una alternativa basada en (nano) materiales sintetizados por técnicas de química coloidal. La posibilidad de procesar nanomateriales en solución permite fabricar semiconductores con propiedades ópticas (emisión, absorción, dispersión de luz) que pueden diseñarse durante la síntesis. Además, su naturaleza coloidal permite integrarlas en cualquier arquitectura óptica mediante sencillas técnicas de impresión en tinta. En este contexto, lo…
Characterisation of single semiconductor nanowires by non-destructive spectroscopies
2015
Los nanohilos semiconductores (NWs, de su nombre inglés, nanowires) tienen una amplia gama de aplicaciones en el campo de la optoelectrónica (emisores de luz y diodos láser), nano-electrónica (circuitos lógicos y transistores de efecto de campo), y detección y producción de energía (células solares). En términos generales, los NWs pueden ser descritos como nanoestructuras de forma alargada con diámetros que van típicamente de decenas a cientos de nanómetros, y con longitudes que oscilan desde pocas hasta las decenas de micras. Dicha morfología ofrece dos ventajas principales en comparación con las capas: su alta relación superficie-volumen y su mayor calidad cristalina, ambas beneficiosas p…
Optical Properties of III-V Nanowires and Their Application for Charge Transport and Single-Photon Emission
2012
This work covers the optical characterization of III-V semiconductor nanowires and their application for charge transport and for single-photon emission. InAs nanowires have been investigated by Raman scattering and PL spectroscopy. The possibility to grow nanowires with a crystal structure different from its bulk counterpart has aroused a lot of interest in their optical and electronic properties. Here, the optical phonon modes of wurtzite InAs nanowires have been studied by polarized Raman scattering. For the first time, Raman measurements on a single InAs nanowire have revealed the A1(TO) and E2h optical phonon modes of the wurtzite structure. Additional resonant Raman scattering experim…
A novel technique for opus vermiculatum mosaic rendering
2006
In this paper we present a method to generate a digital mosaic starting from a raster input image. Mosaics generation of artistic quality is challenging. The basic elements, the tiles, typically small polygons, must be packed tightly, emphasizing orientations chosen by the artist. An adhoc boundaries detection have to be performed according to the directional guidelines. Different mosaic styles can be automatically rendered, depending on artistic techniques considered (“opus musivum”, “opus vermiculatum”, etc.). The proposed method is able to reproduce the colors of the original image emphasizing relevant boundaries by placing tiles along their direction. The boundaries detection is based o…
Determination of Neodymium Diphthalocyanine and its Utilization in Qualitative and Quantitative Evaluation of Synthetic Products
1993
Przedstawiono prostą metodę spektrofotometryczną w zakresie VIS, ilościowego oznaczania diftalocyjaniny neodymu, zarówno w surowych produktach reakcji syntezy jak i oczyszczonym materiale. Polega ona na pomiarach absorbancji badanych próbek w roztworze DMF przy czterech różnych długościach fal, tj. 500, 633, 671 i 800 nm. Zawartość diftalocyjaniny oblicza się z krzywej kalibracyjnej, przedstawionej w postaci równania liniowego.