Accelerated electron beam induced breakdown of commercial WO3 into nanorods in the presence of triethylamine

Tungsten oxide nanorods were prepared from commercial crystalline WO(3) particles treated with triethylamine under electron beam irradiation in an electron microscope operating at 200 kV. The amine acts as a molecular knife, cleaving the particles under beam irradiation.     

Solid-to-liquid and gas-to-liquid transformation of alkanes under accelerated electron beam irradiation

A zero-waste method has been suggested for radiation-thermal cracking of Fischer–Tropsch waxes. The method is realized in the circulating mode and is based on the indirect action of radiation on the wax dissolved in methane or other gaseous hydrocarbons. The duration of exposure to irradiation of the feedstock components depends on their volatility. The method is characterized by the increased fixation yield of the gas. The major fraction of the final product is gasoline rich in isoalkanes.     

Study on the radiation degradation of polyether-polyurethane induced by electron beam

Polyether-urethane samples were irradiated at the dose range from 10 to 2000 kGy by 2 MeV electron beams. Volatile species from the polymer degradation were analyzed quantitatively and qualitatively with GC/MS. Thermal properties and micro-phase separation of the samples were examined by TG and the morphology was studied by TEM and SEM. The results show that the irradiated polyether-polyurethane evolves CO₂, H₂, CH₄ and C₂H₆, etc. The thermal stabilities between the hard and soft segments in the irradiated samples are different. At high doses, the phase separation in the sample is predominant and the hard segment of sample is more stable. The dose rate affects the soft segment of the irradiated sample much more.     

Investigation of carbonaceous insulating films by electron beam X-ray microanalysis

Quantitative investigations of insulators by electron beam X-ray microanalysis are normally only possible using special preparation techniques for the samples. Samples were coated by evaporation with thin carbon films, but the analysis will fail if the samples themselves contain carbon. Two ways are proposed for solving this problem. Samples and reference samples with similar composition were initially coated by evaporation with carbon. The k-ratios necessary for the determination of element concentrations were calculated either experimentally by relation of the intensities to those of carbon standards or by computer calculation of the film thicknesses using the k-ratios of reference samples. By means of this calculation it was possible to correct the usually measured k-ratios or intensities of samples via modified depth distribution functions.     

Investigation of resonant inner-shell processes with an electron beam ion trap

The collision processes of highly charged ions with electrons have been studied with an electron beam ion trap. Resonant inner-shell processes such as dielectronic recombination and resonant excitation double autoionization were investigated by observing the number ratio of extracted ions with adjacent charge states.     

Dissociative electron attachment to Pt(PF3)4--a precursor for focused electron beam induced processing (FEBIP)

Experimental absolute cross sections for dissociative electron attachment (DEA) to Pt(PF(3))(4) are presented. Fragment anions resulting from the loss of one, two, three and four PF(3) ligands as well as the Pt(PF(3))F(-) and the F(-) ions were observed. The parent anion Pt(PF(3)) is too short-lived to be detected. The dominant process is loss of one ligand, with a very large cross section of 20?000 pm(2); the other processes are about 200× weaker, with cross sections around 100 pm(2), the naked Pt(-) anion is formed with a cross section of only 1.8 pm(2). The resonances responsible for the DEA bands were assigned based on comparison with electron energy-loss spectra and spectra of vibrational excitation by electron impact. Bands around 0.5 eV and 2 eV were assigned to shape resonances with single occupation of virtual orbitals. A DEA band at 5.9 eV was assigned to a core-excited resonance corresponding to an electron very weakly bound to the lowest excited state. An F(-) band at 12.1 eV is assigned to a core excited resonance with a vacancy in an orbital corresponding to the 2nd ionization energy of the PF(3) ligand. Implications of these findings for FEBIP are discussed.     

Advanced curing technologies using photo- and electron beam induced cationic polymerization

Diaryliodonium and triarylsulfonium salts mediate photo-, γ-ray and e-beam induced cationic polymerizations. Examples of these three types of polymerizations are described. The potential use of this new methodology for the rapid fabrication of carbon fiber reinforced composites is detailed.     

Atomic structural rearrangements induced by electron beam heating of coalesced palladium particles

Change in the atomic surface structure of small coalesced palladium particles is shown by High Resolution Electron Microscopy imaging; these atomic surface restructuration events during observation are induced by the electron beam irradiation. They include atom evaporation from specific crystallite facets, surface diffusion of atoms which consecutively affects the particle morphology especially in the case of multiple-twinned particles and the growth of crystallite parts and resulting strains.     

Investigation of copper patinas using ion beam analysis and scanning electron microscopy

Ion beam analysis (IBA) techniques were applied successfully to the investigation of non‐corroded and artificially corroded patina layers grown on copper substrates in order to explore their potential use in the study of degradation phenomena of copper and copper alloys subjected to chemical treatment and exposed to selected environmental conditions. Rutherford backscattering spectroscopy (RBS) with deuterons as projectiles and the nuclear reactions ¹⁶O(d,p)¹⁷O and ³²S(p,p′γ)³²S were applied to the investigation of the depth distribution of oxygen and sulphur in near‐surface layers of synthetic patina consisting of mineral phases corresponding to chalcanthite as well as to cuprite + chalcanthite and antlerite + brochantite + chalcanthite. Electrochemical techniques (potentiodynamic polarization and cyclic voltammetry in 0.5 M Na₂SO₄) were used for artificial acceleration and study of the corrosion processes, and scanning electron microscopy (SEM/EDS) was used for examination of the surface morphology of the samples. A patinated roof sample from the Vienna Hofburg also was investigated using the same techniques. The measurement showed that IBA can provide valuable information for the study of patina near‐surface layers of thickness up to a few micrometres and indicated that cuprite was the mineral phase primarily formed on the copper substrates and the main component of the interface between the patina layer and the metallic substrate. The investigated copper patinas looked rather heterogeneous and were characterized by high porosity. Mixed patinas exhibited considerable stability to further corrosive attack. Copyright © 2005 John Wiley & Sons, Ltd.     

Effects of electron beam preirradiation on the γ radiolysis of polyethylene

The γ radiolysis of polyethylene preirradiated with electron beams to 3 Mrad was carried out at 30–100°C in vacuo with a dose rate of 6.35 × 10⁵ rad/hr. The hydrogen formation in the γ radiolysis was little affected by the preirradiation of electron beams, whereas the formation of trans-vinylene unsaturation and gel was somewhat retarded. The rates of the formation of hydrogen and trans-vinylene unsaturation were described by the zero-order formation kinetics with respect to each concentration combined with the first-order disappearance. The apparent rate constants and activation energies for the formation and disappearance of hydrogen and trans-vinylene unsaturation were almost independent of the preirradiation. The gel fraction was analyzed by using the Charlesby–Pinner equation. The G values of crosslinking and main chain scission were increased by the preirradiation, whereas their activation energies remained unaltered. On the basis of these results the effects of preirradiation on the reactions induced by γ rays in polyethylene were discussed.     

Evaluation of potential induced radioactivity in medical products as a function of electron energy in electron beam sterilization

Commercial sterilization of medical devices may be performed using electron beam irradiators at various electron energies. The potential for activating components of the devices has been discussed, with current standards stating that electron energy greater than 10 MeV requires assessment of potential induced radioactivity. This paper evaluates the potential for induced activity in medical products sterilized in electron beam as a function of the electron maximum energy. Monte Carlo simulation of a surrogate medical device was used to calculate photon and neutron fields resulting from electron irradiation, which were used to calculate concentrations for several radionuclides.The experiments confirmed that 10 MeV is a conservative assumption for limiting induced radioactivity. However, under the conditions as evaluated, which is a limited total quantity of metal in the material being irradiated and absent a limited number of elements; the amount of induced activity at 12 MeV could also be considered insignificant. The comparison of the sum-of-fractions to the US Nuclear Regulatory Commission exempt concentration limits is less than unity for all energies below 12.1 MeV, which suggests that there is minimal probability of significant induced activity at energies above the 10 MeV upper energy limit.     

The characterization of latex particles prepared by pulsed electron beam induced emulsion polymerization

The emulsion polymerization of styrene (St) and methyl methacrylate (MMA) induced by 10 MeV pulsed electron beams (PEB) was investigated. The monomer conversion of MMA and St was found to be very low so that the final prepared poly(methyl methacrylate) (P(MMA)) and polystyrene (PS) latex particles exhibit porous structures, as verified by TEM and SEM observations. The results of dynamic light scattering (DLS) and gel permeation chromatography (GPC) showed that both the particle size and the molecular weight of PS and PMMA latexes decrease with the increase of the absorbed dose. However, the molecular weights and the particle sizes of the PS and PMMA latexes change differently with the irradiation time. This work indicated that emulsion polymerization induced by high energy electron beam has an advantage over that induced by γ-ray or chemical initiators in the preparation of latex with a low molecular weight and porous structure.     

Investigation of antioxidant and electron beam radiation effects on the thermal oxidation stability of low-density polyethylene

Effect of various antioxidants on the thermal oxidation stability of LDPE and X-LDPE has been investigated. To achieve this purpose, miscellaneous commercial grade antioxidants such as Irganox 1010, Irganox1076, Irgafos168, Irganox B225, and Chimassorb 944 were selected. Then, formulations based on different content of antioxidant were prepared. The samples were crosslinked by exposure to electron beam irradiation. To assess the thermal oxidation stability of samples, oxidation induction time (OIT) test was accomplished on both the irradiated and unirradiated specimens. Ageing tests were carried out in order to evaluate the thermal oxidation stability of irradiated X-LDPE. The results indicate that Irganox 1010 is the most effective antioxidant amongst the selected ones, concerning thermal oxidation stability of LDPE, before and after aging test.     

Modelling molecular weight changes induced in polydimethylsiloxane by gamma and electron beam irradiation

A commercial linear polydimethylsiloxane (PDMS) was subject to gamma irradiation under vacuum and in air, as well as to accelerated electron beam radiolysis (EB). All irradiation treatments were done at room temperature. The molecular weight changes induced by the radiation processes have been investigated using size exclusion chromatography (SEC) with refraction index (RI) and multi angle laser light scattering (MALLS) detectors to obtain the number and weight average molecular weights of the irradiated samples.

The analysis of the data indicates that crosslinking reactions predominated over scission reactions in all cases. Gamma irradiation under vacuum was the most efficient process within the analyzed dose range, reaching the gel point earlier. Irradiation in the presence of oxygen induces oxidative effects, both in gamma and EB irradiations. A previously developed mathematical model of the irradiation process that accounts for simultaneous scission and crosslinking and allows for both H and Y crosslinks fitted well the measured molecular weight data.     

An investigation on focused electron/ion beam induced degradation mechanisms of conjugated polymers

Irradiation damage, caused by the use of beams in the electron microscopes, leads to undesired physical/chemical material property changes or uncontrollable modification of structures that are being processed. Particularly, soft matter such as polymers or biological materials is highly susceptible and very much prone to react on irradiation by electron and ion beams. The effect is even higher when materials are subjected to energetic species such as ions that possess high momentum and relatively low mean path due to their mass. Especially when Ga(+) ions (used as the ion source in Focused Ion Beam (FIB) instruments) are considered, the end-effect might even be the total loss of the material's properties. This paper will discuss the possible types of degradation mechanisms and defect formations that can take place during ion and electron beam irradiation of the conjugated polymers: e.g. polyfluorene (PF) and poly-3-hexylthiophene (P3HT) thin films. For the investigation of the irradiation induced degradation mechanisms in this study, complementary analytical techniques such as Raman Spectroscopy (RS), Infrared Spectroscopy (IR), Electron Energy Loss Spectroscopy (EELS), Atomic Force Microscopy (AFM), and Fluorescence Microscopy including Photoluminescence (PL) and Electroluminescence (EL) Microscopy were applied.     

On the electron affinity of Cu atom

The electron affinity (EA) of the Cu atom is computed using large STO and GTO basis sets at several levels of correlation. The best computed value is 1