Search results for "Toe"
showing 10 items of 3824 documents
The effect of oxygenation on the radiation hardness of silicon studied by surface photovoltage method
2002
The effect of oxygenation on the radiation hardness of silicon detectors was studied. Oxygen-enriched and standard float-zone silicon pin-diodes and oxidized samples were processed and irradiated with 15-MeV protons. After the irradiations, the surface photovoltage (SPV) method was applied to extract minority carrier diffusion lengths of the silicon samples. Adding oxygen to silicon was found to improve the radiation hardness of silicon. The effect was visible in minority carrier diffusion lengths as well as in reverse bias leakage currents. The suitability of SPV method for characterizing irradiated silicon samples was proved.
Irradiation Effects in Optical Fibers
2010
Intrinsic and extrinsic optical fiber-based sensors are promising devices to be used in very different and complex environments, by their very nature: capabilities to work under electromagnetic fields; possibility to carry multiplexed signals (time, wavelength multiplexing); small size and low mass; ability to handle multi-parameter measurements in distributed configuration; possibility to monitor sites far away from the controller. In the case of the optical fibers, the possibility to be incorporated into various types of sensors and actuators, free of additional hazards (i.e. fire, explosion), made them promising candidates to operate in adverse conditions as those required by space appli…
Annealing study of oxygenated and non-oxygenated float zone silicon irradiated with protons
2003
Abstract Introducing oxygen into the silicon material is believed to improve the radiation hardness of silicon detectors. In this study, oxygenated and non-oxygenated silicon samples were processed and irradiated with 15 MeV protons. In order to speed up the defect reactions after the exposure to particle radiation, the samples were heat treated at elevated temperatures. In this way, the long-term stability of silicon detectors in hostile radiation environment could be estimated. Current–voltage measurements and Surface Photovoltage (SPV) method were used to characterize the samples.
X-ray Photoelectron-spectroscopy Investigation of Pumice-supported Nickel-catalysts
1995
Pumice-supported nickel catalysts, prepared by the method of slow homogeneous precipitation with urea, were analysed by x-ray photoelectron spectroscopy (XPS). By comparison with similarly prepared silica- and alumina-supported nickel catalysts, a preferential interaction of Ni2+ with Al3+ of the support has been determined. A quantitative XPS analysis indicated large segregation of nickel to the surface. The treatment with H2 at 673 K and 1073 K produced a partial reduction of Ni+2 to Ni0. The extent of the reduction was largest at 1073 K and in this case the reduced Ni in the metallic phase was detectable by x-ray diffraction. A decrease of the Ni 2p/Si 2p intensity ratio occurring in the…
Study by static SIMS, XPS and UPS of the adsorption of cyanogen on (100) Ni surfaces
2000
Abstract The interaction of cyanogen with (100) Ni surfaces at room temperature was studied using secondary ion mass spectrometry in a static mode, and photoemission spectroscopies (XPS and UPS). It has been shown that cyanogen is adsorbed on this nickel surface in a dissociative mode: atomic carbon and nitrogen are present on the surface as well as CN fragments. These adsorbed species have been characterized by XPS and UPS. Increasing the temperature in the 400 K range increases the rate of the dissociation reaction of CN into atomic carbon and nitrogen. Moreover carbon is found to dissolved into the bulk for temperatures as low as 475 K. No evidence has been found of a polymerized form of…
Precatalyst or dosing-device? The [Pd2{μ-(C6H4) PPh2}2{μ-O2C(C6H5)}2] complex anchored on a carboxypolystyrene polymer as an effective supplier of pa…
2020
Abstract A new catalyst has been synthesized from the precursor [Pd2{μ-(C6H4) PPh2}2 {μ-O2C(C6H5)}2] immobilized on a carboxypolystyrene polymer that exhibits an excellent dispersion of the Pd (II) centers, reusability, and catalytic activity in front of phenyl bromides. The activity of this new material was studied in detail for the Suzuki-Miyaura reaction and compared to that of Pd nanoparticles (NPs) supported on UVM-7 (a mesoporous silica), and Pd NPs stabilized with polyvinylpirrolydone. The homogeneous/heterogeneous character of the catalytic process was determined from the results of the hot-filtration, centrifugation, poisoning, three phases tests, and from differential sensitivity …
ORR Activity and Stability of Co-N/C Catalysts Based on Silicon Carbide Derived Carbon and the Impact of Loading in Acidic Media
2018
This work was supported by the EU through the European Regional Development Fund under projects TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011), NAMUR ”Nanomaterials - research and applications” (3.2.0304.12-0397) and by the Estonian institutional research grant No. IUT20-13.
Structural Characterization of Surfactant-Coated Bimetallic Cobalt/Nickel Nanoclusters by XPS, EXAFS, WAXS, and SAXS
2011
Cobalt nickel bimetallic nanoparticles were synthesized by changing the sequence of the chemical reduction of Co(II) and Ni(II) ions confined in the core of bis(2-ethylhexyl)phosphate (2)., and Ni(DEHP)(2). The reduction was carried out by mixing, sequentially or contemporaneously, fixed amounts of n-heptane solution of Co(DEHP)2 and Ni(DEHP)2 micelles with a solution of sodium borohydride in ethanol at a fixed (reductant)/(total metal) molar ratio. This procedure involves the rapid formation of surfactant-coated nanoparticles, indicated as Co/Ni (Co after Ni), Ni/Co (Ni after Co), and Co + Ni (simultaneous), followed by their slow separation as nanostructures embedded in a sodium bis(2-eth…
Study of the role of sulfur functionalities in humic acids for uranium(VI) complexation
2009
Humic substances influence the speciation and migration behavior of toxic and radiotoxic metal ions, such as actinides, in the environment. Depending on their origin, humic substances contain different amounts of sulfur ranging from 0.1 to 3.6% and 0.5 to 1.43% in soil and aquatic humic substances, respectively [1]. Reduced, intermediately oxidized and highly oxidized sulfur functionalities occur in humic substances [1]. Although sulfur functionalities occur in small concentrations, they can play an important role in the complexation of selected metal ions. Knowledge about the impact of sulfur functionalities on the metal ion complexation by humic substances and their significance compared …
Total oxidation of naphthalene using bulk manganese oxide catalysts
2013
Several Mn2O3 catalysts have been synthesized using different preparation methods and tested for the total oxidation of naphthalene, a model polycyclic aromatic compound. The catalysts have been characterized by several physico-chemical techniques such as XRD, TPR, XPS, EDX and TEM. The surface area of the catalyst seems to be of paramount importance, since the mass normalized activity of catalysts increases as the surface area of the Mn2O3 catalysts increases. Consequently, a high surface area ordered mesoporous Mn2O3 catalyst, obtained through a nanocasting route using mesoporous KIT-6 silica as a hard template, was the most efficient catalyst for the deep oxidation of naphthalene. In add…