Irradiation effects technique

Since 1958, more than 20 nuclides of actinides ranging from neptunium to einsteinium were identified and prepared for tracer studies. From neutron-irradiated uranium samples 2 9Np was adjusted to the pentavalent state and separated by TBP extraction from perchloric acid media. Plutonium-239 was separated by TBP extraction from nitric acid solution followed by anion exchange in a system of Dowex-1 resin and nitric acid. Neptunium-237 was separated from a spent fuel solution of JRR-1 (Japan Research Reactor -1) using anion exchange and TBP extraction. The TBP extraction in the hydrochloric acid medium is a simple and effective technique to purify neptunium from plutonium contamination. On the other hand, both anion exchange and solvent extraction with HDEHP could be used to separate tracer scale plutonium from irradiated neptunium targets. 

Finally, a few articles have appeared on chemiluminescence of polymers. This technique has been used to detect hydroxy radicals in wood oxidation,y-irradiation effects on polyethylene, oxidation of nitrile-butadiene rubber, rubber under stress,antioxidant efficiencies in polyethylene, reactions of peroxy radicals, stereoregularity in poly(propylene), colour development in epoxy resins and structural changes in thermally aged poly(phenylene sulfide). ... 

Irradiation generates free radicals via radiolysis of monomers or energy transfer through initiators and can also produce radicals on polymer surfaces. RIGP has been demonstrated as an effective technique to graft polymers from substrates." Liu and co-workers" developed a single-step method of in... 

The NMR techniques were also used to analyze different structural, surface reactions, reaction mechanisms, and other aspects related to the surface chemistry of silicas. For instance. Brunet et al. (2008) studied the electron irradiation effects on controlled-pore borosilicate glasses (CPGs at 8 and 50 nm in pore size, 96% Si02 and 3% B2O3) using multinuclear solid-state NMR technique. H MAS NMR was used to study the surface proton sites. They showed that the irradiation leads to a dehydration of the material. The observed variation of the Q4, Q3, and Q2 species from H- Si CPM AS spectra showed an increase of the surface polymerization under irradiation, implying in majority a Q2 to Q3/Q4 conversion mechanism, and CPMAS measurements exhibited an increase in... 

The XPS study of ion-beam irradiation effects in polyamide layers have been studied by Karpuzov et al. (1989). Thin polyamide films deposited on silicon or metal covered glass-ceramic substrates were exposed to ion bombardment at different fluences ranging from 1 x 10 to 1.5x 10 cm. The XPS technique was used to study the polymer stoichiometry of the near surface layers ( 75 A) before and after the bombardment. The results show that the stoichiometric ratio of O, N, and C-groups remains approximately constant with depth for unirradiated samples. 

Heitmann J, Muller F, Yi L, Zacharias M, Kovalev D, Eichhom F (2004) Excitons in Si nanocrystals confinement and migration effects. Phys Rev B 69(19) 195309-l-195309-7 Huang YM (1997) Positron irradiation a technique for modifying the photoluminescent structures of porous silicon. Appl Phys Lett 71(26) 3850-3852 Huie RE, Neta P (2002) Chemistry of reactive oxygen species. In Gilbert DL, Colton CA (eds) Reactive oxygen species in biological systems an interdisciplinary approach. Kluwer, New York, pp 33-73... 

C by using a post-irradiation annealing technique. The irradiation dose was 1.2 x 10fissions/cm. The effect of the O potential upon the diffiisivity in UO2 was also... 

In the early stages of ESR application to polymer research, many studies on the identification of free radicals produced by irradiation with ionizing radiation, x-ray, and ultraviolet light were made. Some of the irradiation effects in polymeric materials were considered to originate from the radical processes and, therefore, clear identification of the radicals trapped in irradiated polymers was one of the most important problems at that stage. In this meaning, ESR application was considered to be a very convenient technique for this purpose, because detection and identification of the free radicals bearing unpaired electrons in principle can be done easily by the ESR method without any chemical modification of the materials. 

The irradiation effect on the PL spectrum of PVK-C60 form nanocomposite films was also studied [281]. The physical jet deposition technique [282] was applied to fabricate the PVK-C60 form composite films, including multilayer and mixed films. Multilayer PVK-C60 form films were fabricated by alternatively depositing PVK and C60 materials on the fused silica substrate with nearly equal layer thickness. It was found that lengthy irradiation with a 532 nm picoseconds laser beam steadily increased the intensity of PL emission of PVK at 630 nm in the mixed film, reflecting that the population of the triplet state of the C60 molecule has a great effect on the excitation transfer process in the nanocomposite films. 

UV irradiation of polymers has been observed to be an effective technique to modify polymers for biomolecule immobilization. The polymer surface is modified by photo-induced graft polymerization of different monomers, such as acrylic acid,. -acrylamidomethylpropane sulfonic acid, and styrene sulfonic acid. All these monomers have ionic functionality and lead to high graft densities for the immobilization of collagen and other proteins. The surface density of polyacrylic acid grafts reaches up to lOOpg/cm under appropriate reaction conditions and Is enough for protein immobilization [36]. 

Experimental profiles in the case of Te implanted Si samples irradiated at different substrate temperatures with 1.5 J/cm -30 nm ruby laser pulses are shown in Fig.9. The concentrations as measured by channeling effect technique in combination with MeV He Rutherford backscattering, indicate that the higher surface accumulation is obtained at 600K substrate temperature. 

Irradiation effects and microstructural changes in Generation IV reactor materials have been discussed in this chapter. The role of irradiation-induced point, hne, and volume defects in performance of steels has been discussed and radiation-induced segregation and precipitation mechanisms have been dehneated. New characterization techniques recently deployed in the nuclear materials field have been introduced and advantages and limitations of each technique have been provided. 

In the work of Rong et al. [108], various polymers were grafted on the surface of nanoscale silica filler particles through the simultaneous irradiation polymerization technique. In this way, the modified nanoparticles can be more effectively utilized in thermoplastics (such as PP) than conventional particulate fillers, when using the same direct compounding technology. 

CP is an effective technique to significantly increase the sensitivity of nonabundant spins S dipolarly coupled with abundant spins I. The principle of the CP experiment is demonstrated in Fig. 5D. In this technique, an indirect excitation of dilute spins S (which are observed) by polarization transfer from abundant spins / (mostly H) is employed. The CP experiment consists of three steps (1) excitation of the I spins by n/2 pulse, (2) polarization transfer from Ito S spins by simultaneous irradiation of the rf fields and of the I and S spins... 

The physical techniques used in IC analysis all employ some type of primary analytical beam to irradiate a substrate and interact with the substrate s physical or chemical properties, producing a secondary effect that is measured and interpreted. The three most commonly used analytical beams are electron, ion, and photon x-ray beams. Each combination of primary irradiation and secondary effect defines a specific analytical technique. The IC substrate properties that are most frequendy analyzed include size, elemental and compositional identification, topology, morphology, lateral and depth resolution of surface features or implantation profiles, and film thickness and conformance. A summary of commonly used analytical techniques for VLSI technology can be found in Table 3. 

High-resolution transmission electron microscopy (HREM) is the technique best suited for the structural characterization of nanometer-sized graphitic particles. In-situ processing of fullerene-related structures may be performed, and it has been shown that carbonaceous materials transform themselves into quasi-spherical onion-like graphitic particles under the effect of intense electron irradiation[l 1],... 

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