719 research outputs found
Semiconductor quantum dot-doped sol–gel materials
No full textIn this chapter we present an overview of optical gas sensors based on sol-gel materials, with particular emphasis on surface plasmon resonance-based sensor. The definition of optical gas sensor and the main parameters used for characterizing gas sensors are described in the introduction. A section is devoted to plasmonic gas sensors which are optical sensors that use localized surface plasmons or extended surface plasmons as transducing platform. Surface plasmons are very sensitive to dielectric variations of the environment or to electron exchange and these effects have been exploited for the realization of sensitive gas sensors. Several examples of sol-gel based nanomaterials developed by our group and used as sensitive materials for optical gas sensors are presented
Sol-gel film containing metal and semiconductor nanoparticles for gas sensing
No full textFunctional nanocomposite films have been obtained by doping sol-gel films with metal and semiconductor nanoparticles for gas sensor application. Three synthetic approaches were adopted, each of them characterized by a systematic increase of the final materials morphology, structure and micro-structure control. The synthesized layers comprised of an inorganic porous matrix (SiO2, TiO2 and NiO) containing nanosized metal (Au, Pt) or semicon-ductor crystals (NiO), and were shown to be active materials for chemical recognition of H2 and CO. The films were deposited onto different sensing supports, leading to successful gas detection via optical, conductometric and surface acoustic wave interfaces
Sol-gel thin films for photonic application
No full textFor the fabrication of photonic devices the sol-gel technique is a potentially lucrative alternative to methods such as physical vapor or chemical vapor deposition because of its solution-processability, low cost and relative ease of production. In this work we harness this potential by developing based photonic devices which incorporate highly luminescent CdSe@ZnS core-shell semiconductor quantum dots (QDs) doped within inorganic (TiO2, ZrO2) or hybrid organic-inorganic sol-gel films. As a pre-requisite to the formation of such devices, luminescent waveguides emitting between green and red have been obtained and their optical properties have been characterized. The photochemical stability of these waveguides was found to highly dependent on the exact sol-gel material used. QDs:Titania based composites were found to be inherently photo-unstable due to photoelectron injection into the bulk matrix and subsequent nanocrystal oxidation. In comparison, zirconia composites were significantly more robust with high photoluminescence retained up to annealing temperatures of 300 °C. Despite this difference in photo-chemical stability, both titania and zirconia composite waveguides exhibited amplified stimulated emission (ASE) with one-photon and two-photon optical pumping, however only zirconia based waveguides exhibited long term photostability. This Zirconia based films have been used for the realization of distributed feedback lasers and Bragg micro-cavities
Detecting H2S oscillatory response using surface plasmon spectroscopy
No full textThe oscillatory change in the optical absorbance of NiO-TiO2 film containing Au nanoparticles in the presence of H2S gas are investigated. The oscillatory phenomena could be monitored by looking at the variation of the surface plasmon resonance peak of the Au nanoparticles embedded in the TiO2-NiO matrix. Au nanoparticles act as optical probes in the detection of H2S, while the oxide matrix is responsible for the catalytic oxidation of H2S. To the best of our knowledge, it is the first time that oscillatory phenomena are monitored by optical spectroscopy
Sol-gel thin films for plasmonic gas sensors
No full textPlasmonic gas sensors are optical sensors that use localized surface plasmons or extended surface plasmons as transducing platform. Surface plasmons are very sensitive to dielectric variations of the environment or to electron exchange, and these effects have been exploited for the realization of sensitive gas sensors. In this paper, we review our research work of the last few years on the synthesis and the gas sensing properties of sol-gel based nanomaterials for plasmonic sensors
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