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Photonic crystals have proven their potential and are nowadays a familiar concept. They have been approached from many scientific and technological flanks. Among the many techniques devised to implement this technology self-assembly has always been one of great popularity surely due to its ease of access and the richness of results offered. Self-assembly is(More)
NATURE | VOL 405 | 25 MAY 2000 | www.nature.com 437 13. Flemings, M. C. Solidi®cation Processing (McGraw Hill, New York, 1974). 14. Swei, G. S., Lando, J. B., Reichert, S. E. & Mauritz, K. A. Encyclopedia of Polymer Science and Engineering Vol. 6, p. 209 (Wiley, New York, 1986). 15. Wittmann, J. C. & Lotz, B. Epitaxial crystallization of polymers on organic(More)
Self-assembly techniques are widely used to grow ordered structures such as, for example, opal-based photonic crystals. Here, we report on photonic glasses, new disordered materials obtained via a modified self-assembling technique. These random materials are solid thin films which exhibit rich novel light diffusion properties originating from the optical(More)
SiO2 encapsulation of alloyed CdSeZnS nanocrystals (NCs) shows differences in terms of optical properties and luminescence quantum yield, depending on the surface composition, size, and ligand content. In this work, emphasis has been placed on the fine control required to obtain luminescent SiO2 encapsulated NCs by studying the role of oleic acid (OA),(More)
High-permittivity dielectric particles with resonant magnetic properties are being explored as constitutive elements of new metamaterials and devices. Magnetic properties of low-loss dielectric nanoparticles in the visible or infrared are not expected due to intrinsic low refractive index of optical media in these regimes. Here we analyze the dipolar(More)
F. García-Santamaría,1,* J. F. Galisteo-López,2 P. V. Braun,1 and C. López2 1Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA 2Instituto de Ciencia de Materiales de Madrid (CSIC), C/ Sor Juana Inés de la Cruz 3, 28049(More)
We present a detailed study of the gain length in an active medium obtained by doping of DNA strands with 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye molecules. The superior thermal stability of the composite and its low quenching permit one to obtain an optical gain coefficient larger than 300 cm(-1). We also demonstrate that such(More)
Physisorbed and structurally bound (surface and internal) water in silica opals are distinguished and quantified by thermogravimetry. By controlled dehydroxylation with thermal annealing, we correlate these forms of water with the silica chemistry. In particular, we find that the silica capability to physically adsorb water from ambient moisture exhibits(More)
The optimization of the procedure to grow accurate amounts of amorphous silicon and germanium by chemical vapor deposition (CVD) free of contamination in opals has been performed. The samples have been optically characterized and results agree with theoretical calculations of band structures. Multilayer systems of both semiconductors have been fabricated.(More)