Search results for "Toe"

Influence of the preparative route on the properties of WOx–ZrO2 catalysts: A detailed structural, spectroscopic, and catalytic study

2007

Abstract Two series of tungstated zirconia (WZ) solid acids covering a wide range of tungsten surface densities ( δ, W at/nm2 ) were prepared by nonconventional impregnation and coprecipitation routes, leading to samples with enhanced surface area ( ∼ 70 – 120 m 2 / g ) on annealing at 973–1073 K. The materials were thoroughly characterized by N2 physisorption , XRD, Raman, XPS, H 2-TPR, and DR UV–vis spectroscopy. The catalytic behavior of the Pt-promoted WZ catalysts (1 wt% Pt) was evaluated for the hydroconversion of n-hexadecane used as model feed representative of Fischer–Tropsch waxes. Both series of catalysts displayed a pronounced maximum in the reaction rate and a minimum in the se…

Electro-optic dynamics in thermally poled Ge core doped silica fibre

2003

The electro-optic (EO) dynamics of a twin hole germania core doped fibre when an applied electric field at elevated temperature modifies the symmetry of glass is reported. An EO peak was recorded after 10 min poling. The results were interpreted with a two-space charge model.

Supercontinuum generation with 532 nm quasi-continuum pulses in photonic crystal fibre tapers

2007

We report experimental results on supercontinuum generation in PCF tapers using quasi-continuous pump pulses of 7 ns duration at 532 nm. SC generation in normal and anomalous dispersion regimes are presented. Introduction Supercontinuum generation (SC) in photonic crystal fibres (PCF), fibre tapers, and PCF tapers has been demonstrated in the past with pump pulses of fs, ps, and tenths of ns duration [1-2]. Here, we present experimental results on SC generation in PCF tapers using quasi-continuous pump pulses of 7 ns duration at 532 nm. Fabrication of the PCF tapers The PCF from which the tapers were made, was a large-air-hole PCF ("cobweb" PCF) with two rings of air holes around a solid si…

Studio della resistenza alla corrosione di acciai impiegati nell’industria alimentare e delle bevande

2020

In the present study we performed the physico-chemical characterization of passive films grown on different stainless steel grades after long exposure time in hot purified water (HPW). In order to get more insight into dissolution phenomena that can induce rouging on equipment materials typically involved in food and beverage industries, 304L, 316L and a super duplex 2507 SS samples were passivated at the open circuit potential by different immersion times in HPW at 60°C. Photoelectrochemical and Electrochemical Impedance measurements were performed in the attempt to correlate the electronic properties of the passive films (band gap and conductivity type) to their corrosion resistance.

2018

We present the design, fabrication and characterization of long-range surface plasmon polariton waveguide arrays with materials, mainly silicones, carefully selected with the aim to be used as mechanically flexible single-mode optical interconnections, the so-called “plasmonic arc” working at 1.55µm. The fabricated plasmonic arcs show a TM/TE polarization ratio of ~25 dB. By using the cut-back method, the straight propagation loss at 1.55µm is estimated to 0.5-1 dB/mm and coupling loss to ~1-2 dB/facet after dicing. In the free-standing S-curved configuration, the bending loss of single cladding plasmonic arc is 2.2-2.8 dB/90° at bending radius 2.5 mm. For double cladding plasmonic arcs, it…

Frequency conversion of propagating surface plasmon polaritons by organic molecules

2008

We demonstrate frequency conversion of surface plasmon polaritons (SPP) by utilizing the coupling between organic dye molecules and SPP. Launching of SPPs into a plasmonic waveguide is done in two ways: by optically excited molecules and by quantum dots (QDs). QDs are demonstrated to overcome the major problem of bleaching occurring with molecules. The SPP propagates tens of micrometers and clear frequency conversion is observed in the SPP spectrum after passing an area of converter molecules. The use of molecules and QDs as elements of all-plasmonic devices has the potential for high integration and use of self-assembly in fabrication. Peer reviewed

WS2/MoS2 Heterostructures via Thermal Treatment of MoS2 Layers Electrostatically Functionalized with W3S4 Molecular Clusters

2020

The preparation of 2D stacked layers that combine flakes of different nature, gives rise to countless number of heterostructures where new band alignments, defined at the interfaces, control the electronic properties of the system. Among the large family of 2D/2D heterostructures, the one formed by the combination of the most common semiconducting transition metal dichalcogenides WS2/MoS2, has awaken great interest due to its photovoltaic and photoelectrochemical properties. Solution as well as dry physical methods have been developed to optimize the synthesis of these heterostructures. Here a suspension of negatively charged MoS2 flakes is mixed with a methanolic solution of a cationic W3S…

Comparison of the sensitivity to spectral variation of voltage- and current-matched tandem devices with luminescent coupling and thickness optimizati…

2016

Using models that do not take luminescent coupling into account, voltage-matched tandem devices have previously been shown to be less sensitive to spectral variation than their current-matched counterparts. The present paper compares the spectral sensitivity of voltage-matched and current-matched tandem devices by applying a detailed balance model that takes luminescent coupling into account. Current-matched stacks where the thickness of the top cell thickness has been optimized are also considered. The main finding is that luminescent coupling reduces the difference in spectral sensitivity between voltage-matched and current-matched devices. There is still a significant difference, however…

Single-molecule controlled emission in planar plasmonic cavities

2014

International audience; We study the fluorescence emission from single dye molecules in coplanar plasmonic cavities composed of a thin gold film surrounded by two in-plane surface plasmon Bragg mirrors. We first discuss the effect of the presence of Bragg mirrors on the radiation diagram of surface plasmon coupled emission. Then, we investigate the role of the planar cavity size by single-molecule fluorescence lifetime imaging. Experimental data are compared to numerical simulations of the decay rates calculated as a function of the molecule orientation and position within the cavity. The creation of new decay channels by coupling to the cavity modes is also discussed. We measure a plasmoni…

Accurate mode characterization of two-mode optical fibers by in-fiber acousto-optics.

2016

Acousto-optic interaction in optical fibers is exploited for the accurate and broadband characterization of two-mode optical fibers. Coupling between LP01 and LP1m modes is produced in a broadband wavelength range. Difference in effective indices, group indices, and chromatic dispersions between the guided modes, are obtained from experimental measurements. Additionally, we show that the technique is suitable to investigate the fine modes structure of LP modes, and some other intriguing features related with modes' cut-off.