Search results for "ELECTRONICS"
showing 10 items of 4340 documents
Effects of radiation and hydrogen-loading on the performances of raman-distributed temperature fiber sensors
2015
International audience; The integration of Raman-distributed temperature fiber-based sensors (RDTS) into the envisioned French deep geological repository for nuclear wastes, called Cigéo requires evaluating how the performances of RDTS evolve in harsh environments, more precisely in presence of H2 or γ-rays. Both H2 and radiations are shown to affect the temperature measurements made with the single-ended RDTS technology. The amplitudes of the observed effects depend on the different classes of multimode fibers varying in terms of composition and coatings. By selecting the most tolerant fiber structure for the sensing, we could maintain the RDTS performances for such application. A hardeni…
Novel core–shell (TiO2@Silica) nanoparticles for scattering medium in a random laser: higher efficiency, lower laser threshold and lower photodegrada…
2013
There has been growing interest in scattering media in recent years, due to their potential applications as solar collectors, photocatalyzers, random lasers and other novel optical devices. Here, we have introduced a novel core-shell scattering medium for a random laser composed of TiO2@Silica nanoparticles. Higher efficiency, lower laser threshold and long photobleaching lifetime in random lasers were demonstrated. This has introduced a new method or parameter (fraction of absorbed pumping), which opens a new avenue to characterize and study the scattering media. Optical chemical and colloidal stabilities were combined by coating a suitable silica shell onto TiO2 nanoparticles.
Electronic coupling responsible for energy transfer in columnar liquid crystals
1999
Electronic coupling is the driving force for energy transfer in molecular materials and consists of several components. We determine the strength of dipolarrmultipolar coupling and coupling due to orbital overlap for excitation transport in triphenylene columnar liquid crystals. We use time-resolved fluorescence spectroscopy and computer simulations. The fit of the experimental and simulated fluorescence decays reveals that the transfer process is dominated by short range interactions .multipolar and orbital overlap but the contribution of long range dipolar interactions cannot be neglected. q 1999 Elsevier Science B.V. All rights reserved.
Long-Range Order Induced by Intrinsic Repulsion on an Insulating Substrate
2015
An ordered arrangement of molecular stripes with equidistant appearance is formed upon the adsorption of 3-hydroxybenzoic acid onto calcite (10.4) held at room temperature. In a detailed analysis of the next-neighbor stripe distances measured in noncontact atomic force microscopy images at various molecular coverages, we compare the observed stripe arrangement with a random arrangement of noninteracting stripes. The experimentally obtained distance distribution deviates substantially from what is expected for a random distribution of noninteracting stripes, providing direct evidence for the existence of a repulsive interaction between the stripes. At low molecular coverage, where the averag…
UV light energy storage and thermoluminescence in AlN ceramics
2007
AlN ceramics, untreated and subjected to oxygen ion implantation, are studied for potential application in TL dosimetry of UV light. Based on photoluminescence and thermoluminescence measurements there are shown advantages of the selection of the 480 emission band for TL signal recording instead of the previously used 400 nm band: higher intensity of the TL signal, lower fading rate of the accumulated TL signal, excitation region (270-340 nm) corresponding to UV-B range, monitoring of which is actual in UV dosimetry. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Finely tunable laser based on a bulk silicon wafer for gas sensing applications
2016
In this work a very simple continuously tunable laser based on an erbium ring cavity and a silicon wafer is presented. This laser can be tuned with very fine steps, which is a compulsory characteristic for gas sensing applications. Moreover the laser is free of mode hopping within a spectral range sufficiently wide to match one of the ro-vibrational lines of a target molecule. Here the proposed laser reached, at ∼1530 nm, a continuous tuning range of around 950 pm (>100 GHz) before mode hopping occurred, when a silicon wafer of 355 μm thickness was used. Additionally, the laser can be finely tuned with small tuning steps of <12 pm, achieving a resolution of 84.6 pm °C-1 and by using a therm…
Lasing characteristics of a new DCM derivative under flashlamp pumping
1991
Abstract A new DCM derivative (4-dicyanomethylene-2-methyl-6-p-diethanolamino-styryl 4H-pyran or DCM-OH), was tested under flashlamp pumping. This dye lased in the 600–700 nm range with efficiency up to 0.4% at maximum. Lasing performances of DCM-OH in methanol and water-methanol mixture are reported and compared to normal DCM.
Modeling Information Processing Using Nonidentical Coulomb Blockade Nanostructures
2017
In recent years, molecular-protected metallic nanoparticles (NPs) have attracted a great deal of attention. Because of their reduced size, they behave like tiny capacitors so that there is an energy penalty when adding an electron to the NP which suppresses the electric current at a potential lower than a threshold value. This phenomenon is known as Coulomb blockade (CB) and allows the transport of electrons to be modulated through an external gate provided that the energy penalty is higher than the thermal energy. Together with the possibility of tailoring their properties, molecular protected NPs are potential candidates as future components of high density, low consumption electronics. H…
Luminescence of γ-radiation-induced defects in α-quartz
2004
Optical transitions associated with γ-radiation-induced defects in crystalline α-quartz were investigated by photoluminescence excited by both pulsed synchrotron radiation and steady-state light. After a 10 MGy γ-dose we observed two emissions at 4.9 eV (ultraviolet band) and 2.7 eV (blue band) excitable in the range of the induced absorption band at 7.6 eV. These two luminescence bands show a different temperature dependence: the ultraviolet band becomes bright below 80 K; the blue band increases below 180 K, but drops down below 80 K. Both emissions decay in a timescale of a few ns under pulsed excitation, however the blue band could also be observed in slow recombination processes and it…
Stable and long-time operation of a soft x-ray laser for user applications experiments
2011
LASERIX is a high-power laser facility leading to High-repetition-rate XUV laser pumped by Titanium:Sapphire laser. The aim of this laser facility is to offer Soft XRLs in the 30-7 nm range and auxiliary IR beam that could also be used to produce synchronized XUV sources. This experimental configuration highly enhances the scientific opportunities of the facility, giving thus the opportunity to realize both X-ray laser experiments and more generally pump/probe experiments, mixing IR and XUV sources. In this contribution, the main results concerning both the development of XUV sources(X-Ray lasers and HHG sources) and their use for applications are presented.