Showing papers in "Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms in 2005"

Progress in radiation processing of polymers

Abstract: Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from ether radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation of noxious fumes and by products of peroxide degradation. Both the irradiation sources have their merits and limitations. Increased utilization of electron beams for modification and enhancement of polymer materials has been in particular witnessed over the past 40 years. The paper highlights several recent cases of EB utilization to improve key properties of selected plastic products. In paper is provided a survey of radiation processing methods of industrial interest, encompassing technologies which are already commercially well established, through developments in the active R&D stage which show pronounced promise for future commercial use. Radiation cross-linking technologies discussed include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, development of radiation crosslinked SiC fiber, polymer recycling, development of gamma compatible pp, hydrogels etc. Over the years, remarkable advancement has been achieved in radiation processing of natural polymers. Role of radiation in improving the processing of temperature of PCL for use as biodegradable polymer, in accelerated breakdown of cellulose into viscose and enhancement in yields of chitin/chitosan from sea-food waste, is described.

Experimental determination of track cross-section in Gd3Ga5O12 and comparison to the inelastic thermal spike model applied to several materials

Abstract: Single crystals of gadolinium gallium garnet, Gd 3 Ga 5 O 12 have been irradiated with various swift heavy ions ( 32 S, 52 Cr, 63 Cu, 86 Kr, 128 Te, 129 Xe, 181 Ta, 208 Pb, 238 U) in the electronic stopping power regime. The extent of the induced damage is extracted from channelling Rutherford backscattering experiments and the corresponding track radii are deduced. At low beam energy (around 1.5 MeV/u), the electronic stopping power threshold of damage creation is 7.2 ± 1.2 keV/nm while it is 9.3 ± 0.9 keV/nm for beam energy around 6 MeV/u. The inelastic Thermal Spike model (i-TS) is used in order to calculate the track radii versus (d E /d x ) e using λ , the mean diffusion length of the energy deposited on the electrons, as the only fitting parameter model. The i-TS model was extended to some other amorphizable materials like YBa 2 Cu 3 O 7− δ , GeS and LiNbO 3 . The results, combined with previous ones extracted from BaFe 12 O 19 , Y 3 Fe 5 O 12 , Y 3 Al 5 O 12 and α-SiO 2 quartz data, showed that λ decreases when the band gap energy E g increases. By extrapolation and depending of the material, the damage threshold induced by electronic excitation can appear at beam energy as low as 10 −3 to 10 −1 MeV/u.

Differential cross-section of the D(3He, p)4He nuclear reaction and depth profiling of deuterium up to large depths

Abstract: The differential D( 3 He, p) 4 He reaction cross-section was determined at a laboratory angle of 135° for 3 He energies between 05 and 6 MeV Deuterium depth profiles are determined from the measurement of the proton yield as a function of incident 3 He energy with following deconvolution of the obtained yield function This allows deuterium depth profiling to very large depths Deuterium depth profiling to a depth of 7 μm in W and 50 μm in B 4 C is demonstrated The accuracy of the method is discussed

Production of hydrogel wound dressings using gamma radiation

Abstract: Hydrogel wound dressings have been prepared using the gamma rays irradiation technique. The dressings are composed of poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG) and agar. The influence of some process parameters on the properties of the dressings has been investigated as: the gel fraction, maximum swelling, swelling kinetics, and mechanical properties. The gel fraction increases with increasing PVP concentration due to increased crosslink density, and decreases with increasing the PEG concentration. PEG seems to act not only as plasticizer but also to modify the gel properties as gelation% and maximum swelling. The prepared hydrogels dressings could be considered as a good barrier against microbes.

Stability and mobility of self-interstitials and small interstitial clusters in α-iron: ab initio and empirical potential calculations

Abstract: The stability and mobility of self-interstitials and small interstitial clusters, I n , in α-Fe is investigated by means of calculations performed in the framework of the density functional theory using the SIESTA code. The mono-, di- and tri-interstitials are shown to be made of (parallel) 〈1 1 0〉 dumbbells and to migrate by nearest-neighbor translation–rotation jumps, according to Johnson’s mechanism. The 〈1 1 1〉 orientation of the dumbbells becomes energetically more favourable for I 5 and larger clusters. The performance of a semi-empirical potential recently developed for Fe, including ab initio self-interstitial data in the fitted properties, is evaluated over the present results. The superiority over previous semi-empirical potentials is confirmed. Finally the impact of the present results on the formation mechanism of 〈1 0 0〉 loops, observed experimentally in α-Fe is discussed.

Nuclear microprobe – synchrotron synergy: Towards integrated quantitative real-time elemental imaging using PIXE and SXRF

Abstract: The Dynamic Analysis (DA) method, for the projection of quantitative elemental images using Proton Induced X-ray Emission (PIXE), has been extended for use with energy-dispersive Synchrotron X-ray Fluorescence (SXRF) data collected with the X-ray microprobe by making use of similarities and synergy with nuclear microscopy. The broad element sensitivity of PIXE is complemented by the selective nature of SXRF, where the beam energy can be tuned to optimize the sensitivity in a portion of the periodic table. PIXE combined with Proton Induced {gamma}-ray Emission (PIGE) in this study provided images of geological samples of 25 elements, including characteristic X-rays up to the energy of the Nd K lines (37 keV). Maximum sensitivity was achieved for elements around Z {approx} 33 with detection limits of {approx}250 ppb (in 5 h). SXRF using a 16.1 keV photon microbeam provided images of 16 elements, with optimum sensitivity around Z {approx} 35 with detection limits of {approx}70 ppb (in 11 h), an improvement of {approx}2.4 times when corrected for acquisition time.

Effect of γ-radiation on the structure and morphology of polyvinyl alcohol films

Abstract: The structure and morphology of polyvinyl alcohol (PVA) films, deposited from solution, was determined by using Infra Red Spectroscopy (IR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The films were irradiated with gamma rays for various doses up to 20 mrad. The color of the films changed to yellowish-brown after irradiation. The crystallinity percentage, as calculated from XRD and IR spectra, was found to decrease. Additional changes observed in IR absorption bands and XRD revealed the possibility of liberation of –H and –OH groups as well as scission of the main chain.

Current status of adsorbent for metal ions with radiation grafting and crosslinking techniques

Abstract: Removal of toxic metals from streaming water and ground water is important task to preserve environment. Radiation processing of grafting and crosslinking can synthesis adsorbent having high performances. Graft adsorbent can be synthesized by using the conventional polymer like polyethylene having variety shapes such as membrane, cloth, and fiber. Especially, the obtained fibrous adsorbent has 100 times higher rate of adsorption than that of commercialized resin. Fibrous adsorbent of iminodiacetate was applied to the removal of cadmium from the scallop waste. Furthermore, the amidoxime adsorbent is useful for recovery of rare metals such as uranium and vanadium in seawater. Novel fibrous adsorption for arsenic was synthesized by direct grafting of phosphoric monomer and following zirconium-loading. Crosslinked natural polymers like carboxymethyl chitin–chitosan in the paste-like state are applicable for the metal adsorbent. This adsorbent can be biodegraded after usage.

Studies on effective atomic numbers and electron densities in amino acids and sugars in the energy range 30 1333 keV

Abstract: The effective atomic numbers and electron densities of the amino acids glycine, alanine, serine, valine, threonine, leucine, isoleucine, aspartic acid, lysine, glutamic acid, histidine, phenylalanine, arginine, tyrosine, tryptophane and the sugars arabinose, ribose, glucose, galactose, mannose, fructose, rhamnose, maltose, melibiose, melezitose and raffinose at the energies 30.8, 35.0, 81.0, 145, 276.4, 302.9, 356, 383.9, 661.6, 1173 and 1332.5 keV were calculated by using the measured total attenuation cross-sections. The interpolations of total attenuation cross-sections for photons of energy E in elements of atomic number Z was performed using the logarithmic regression analysis of the XCOM data in the photon energy region 30–1500 keV. The best-fit coefficients obtained by a piece wise interpolation method were used to find the effective atomic number and electron density of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

Nuclear resonance fluorescence imaging in non-intrusive cargo inspection

Abstract: Nuclear resonance fluorescence is able to non-intrusively interrogate a region space and measure the isotopic content of the material in that space for any element with atomic number greater than that of helium. The technique involves exposing material to a continuous energy distribution of photons and detecting the scattered photons that have a discrete energy distribution unique to an isotope. The interrogating photons, which range from 2 to 8 MeV, are the most penetrating probes and can “see” through many inches of steel. Determination of the chemical components of the material occupying a region of space greatly enhances the identification of threats such as explosives, fissile materials, toxic materials and weapons of mass destruction. Systems can be designed to involve minimal operator intervention, to minimize dose to the sample, and to provide high throughput at commercial seaports, airports and other entry points.

Modern analysis of ion channeling data by Monte Carlo simulations

Abstract: Basic scheme of ion channeling spectra Monte Carlo simulation is reformulated in terms of statistical sampling. The McChasy simulation code is described and two examples of the code applications are presented. These are: calculation of projectile flux in uranium dioxide crystal and defect analysis for ion implanted InGaAsP/InP superlattice. Virtues and pitfalls of defect analysis using Monte Carlo simulations are discussed.

Transport of ions and biomolecules through single asymmetric nanopores in polymer films

Abstract: Single conical nanopores in polymer foils show ‘rectifying’ diode-like current–voltage (I–V) characteristics, with preferential cation flow in the direction from the narrow to the wide opening [P. Apel, Y.E. Korchev, Z. Siwy, R. Spohr, M. Yoshida, Nucl. Instr. and Meth. B 184 (2001) 337–346, Z. Siwy, D. Dobrev, R. Neumann, C. Trautmann, K. Voss, Appl. Phys. A 76 (2003) 781–785]. To produce single-pore membranes, we irradiated polymer films (polyethylene terephthalate and polyimide) with single heavy ions (using kinetic energies in the GeV range) and subsequently performed asymmetric chemical track-etching. The resulting conical pores had narrow openings of 4–20 nm. The I–V curves of these pores were measured in aqueous KCl solutions of various concentrations and pH values, and it was found that both parameters influence the rectification properties of the pores. For decreasing concentrations, down to 0.1 M, the degree of rectification increases, as predicted by a recently proposed model [Z. Siwy, A. Fulinski, Phys. Rev. Lett. 89 (2002) 198103], however, as the concentration decreases further, the rectification unexpectedly begins to decrease again. We suspect that this is due to conformation changes occurring in the pore. Also, our results have shown that the pores exhibit a non-classical conductance versus electrolyte concentration characteristic, having elevated conductances at low concentrations, for which we propose an explanation based on surface conductivity. Finally, we present an application of the polyimide conical nanopores as single-molecule DNA sensors, with results demonstrating their ability to detect individual plasmid DNA molecules.

Surface modification of steels and magnesium alloy by high current pulsed electron beam

Abstract: High current pulsed electron beam (HCPEB) is now developing as a useful tool for surface modification of materials. When concentrated electron flux transferring its energy into a very thin surface layer within a short pulse time, superfast processes such as heating, melting, evaporation and consequent solidification, as well as dynamic stress induced may impart the surface layer with improved physico-chemical and mechanical properties. This paper presents our research work on surface modification of steels and magnesium alloy with HCPEB of working parameters as electron energy 27 keV, pulse duration ∼1 μs and energy density ∼2.2 J/cm2 per pulse. Investigations performed on carbon steel T8, mold steel D2 and magnesium alloy AZ91HP have shown that the most pronounced changes of phase–structure state and properties occurring in the near-surface layers, while the thickness of the modified layer with improved microhardness (several hundreds of micrometers) is significantly greater than that of the heat-affected zone. The formation mechanisms of surface cratering and non-stationary hardening effect in depth are discussed based on the elucidation of non-equilibrium temperature filed and different kinds of stresses formed during pulsed electron beam melting treatment. After the pulsed electron beam treatments, samples show significant improvements in measurements of wear and corrosion resistance.

Application of poly(lactic acid) modified by radiation crosslinking

Abstract: Poly( l -lactic acid), PLLA was irradiated using electron beam (EB) in the presence of polyfunctional monomers (PFM) as crosslinking agent. Among the PFMs, triallyl isocyanurate (TAIC) at 3% concentration was found to be the most effective for crosslinking of PLLA by irradiation technique. The crosslinked PLLA obtained has heat resistance higher than 200 °C. From this fact, the crosslinked PLLA is applied on heat-shrinkable tube, cup and plate. The shrinkable tube has several advantages such as high heat resistance and transparency. In addition, the unirradiated cup deformed and changed to milky-like transparency but the crosslinked one retained its original shape and transparency after boiling water was poured into the cups. The heat resistance is attributed to the protection of crystallization of crosslinking structure. It is therefore proven that crosslinking technology is beneficial to expanding the application of PLLA.

An algorithm for computing screened Coulomb scattering in Geant4

Abstract: An algorithm has been developed for the G eant 4 Monte-Carlo package for the efficient computation of screened Coulomb interatomic scattering. It explicitly integrates the classical equations of motion for scattering events, resulting in precise tracking of both the projectile and the recoil target nucleus. The algorithm permits the user to plug in an arbitrary screening function, such as Lens–Jensen screening, which is good for backscattering calculations, or Ziegler–Biersack–Littmark screening, which is good for nuclear straggling and implantation problems. This will allow many of the applications of the TRIM and SRIM codes to be extended into the much more general G eant 4 framework where nuclear and other effects can be included.

Characterization of swift heavy ion tracks in CaF2 by scanning force and transmission electron microscopy

Abstract: Single crystals of fluorite (CaF2) were exposed to various swift heavy ions (Ca up to U) of energy 1–11.1 MeV per nucleon, covering a large range of electronic stopping power Se between 4.6 and 35.5 keV/nm. The irradiated (1 1 1) cleaved surfaces were investigated by means of scanning force microscopy in tapping mode. Nanometric hillocks produced by the ion projectiles were analyzed in terms of creation efficiency Eeff, diameter and height values, and diameter–height correlation. Hillock formation appears with a low efficiency above a Se threshold of ∼5 keV/nm. The mean height of these hillocks is approximately constant (∼1 nm) between 5 and 10 keV/nm and increases linearly with Se above 10 keV/nm reaching 12.5 nm for the largest Se value investigated. Similarly, the efficiency grows versus Se achieving 100% for Se > 13 keV/nm where each projectile produces an individual hillock. Above 13 keV/nm, the hillock height and diameter are strongly correlated. The diameter was deduced by graphical deconvolution of the scanning-tip curvature that is determined experimentally for each set of measurements. In the entire Se regime, the mean diameter exhibits a constant value of ∼13 nm, which is significantly larger than 6 nm wide tracks observed by transmission electron microscopy.

Concentration and distribution of cobalt in higher plants: The use of micro-PIXE spectroscopy

Abstract: Cobalt is not classified as an essential element for plants, however, it is usually described as “beneficial”. This trace element can be a contaminant in soils due to agricultural additives or metal refineries. Certain plants species have the ability to extract metals (such as Co) from soils, thus, cleaning the environment. Therefore, knowledge of the physiological mechanisms of metal absorption is required to improve these phytoremediation technologies. Patterns of cobalt accumulation and storage were determined in tomato (Lycopersicon esculentum) and wheat (Triticum aestivum) species. Plants were grown in nutrient solutions, with different Co treatments, using controlled environmental conditions. The spatial distributions of K, Ca, Fe and Co in whole plants, and in leaf and stem sections, were examined by micro-PIXE. In conjunction, total Co concentrations were determined by ICP-MS. Micro-PIXE spectroscopy proved to be a convenient technique for indicating Co concentrations and distribution patterns in these plants. This knowledge aids in the identification of vegetal Co sequestration and, thus, helps to unravel how Co is transported in higher plants.

Modified master equation approach of axial dechanneling in perfect compound crystals

Abstract: The master equation approach of dechanneling based on the channeling concept of Lindhard underestimates the Rutherford backscattering minimum yield of perfect crystals mainly at small depths where the equilibrium in the transverse energy shell is not yet reached. This paper presents a modification of the master equation approach which overcomes this problem. The main idea is to simulate the minimum yield up to a depth z equi where the equilibrium is reached and modify the initial distribution of the ions in the master equation approach in this way that the calculated minimum yield at that depth z equi is equal to the corresponding simulated one. Because the simulated depth interval is small, the numerical calculation is still fast enough to be applied for the evaluation of Rutherford backscattering data. For some examples of perfect crystals the results of the calculated minimum yields are compared with those obtained by full simulations and in two cases also with experimental data.

Synchrotron radiation in biosciences

Abstract: The Center for Synchrotron Biosciences (CSB) operates five beamlines at the National Synchrotron Light Source (NSLS). Infrared (IR) micro-spectroscopy, X-ray absorption spectroscopy, structural proteomics and macromolecular footprinting are among the major technologies available through the Center. IR micro-spectroscopy is used to examine protein-folding in the microsecond time regime, image bone, neurons, seeds and other biological tissues, as well as image samples of interest in the chemical and environmental sciences. Structural proteomics research of New York Structural Genomics Research Consortium (NYSGRC) is steadily increasing the number of solved protein structures, with a goal to solve 100–200 structures per year. To speed up the research, a high-throughput method called ‘metallomics’ was implemented for NYSGRC crystallographers to detect intrinsic anomalous scatterers using X-ray absorption spectroscopy. Hydroxyl radical mediated X-ray footprinting is capable of resolving folding events of RNA, at single base resolution on millisecond timescales using a synchrotron white beam. The high brightness of synchrotron source is essential for CSB projects as it permits the use of smaller sample sizes and/or concentration, and allows studies of more complicated biological systems than with conventional sources.

A relativistic optical-data model for inelastic scattering of electrons and positrons in condensed matter

Abstract: A relativistic optical-data model for the calculation of non-radiative inelastic scattering of electrons and positrons in condensed matter is presented. The scattering is described within the first Born approximation, in terms of longitudinal and transverse interactions. Differential cross sections are determined by a generalized oscillator strength density, which is generated by extending a semi-empirical optical oscillator strength density to non-zero momentum transfers using a modified δ-oscillator as the extension algorithm. The Fermi density-effect correction is obtained from the optical oscillator strength and a simple approximation is proposed to account for its effect on the cross section differential in energy loss. The differential cross sections take relatively simple analytical forms, and various quantities of interest, such as total cross section, stopping power, straggling parameter and restricted inelastic transport cross section are evaluated by a single quadrature. Results are presented for electron and positron energies between 10 eV and 1 GeV.

Mn-doped YAlO3 crystal: a new potential TLD phosphor

Abstract: The paper presents results on study of thermoluminescent dosimetry (TLD) properties of YAlO 3 :Mn crystals for dosimetry of γ-radiation. The TL emission at 530 nm from Mn 2+ ions has been used as a TL signal for detecting of γ-radiation. The studied YAlO 3 :Mn samples have shown a sensitivity to γ-radiation commensurable with commercial LiF:Mg, Ti. Since the YAlO 3 :Mn crystals exhibit linear dose response up to 1 kGy, it makes them a candidate for high-dose dosimetry of ionizing radiation.

Ion and electron track-structure and its effects in silicon: model and calculations

Abstract: The dielectric-function-theory was used for systematic calculations of the inelastic interaction-characteristics of electrons and protons with different energies in silicon. An extended comparison of the calculated data with experiment and with the results of other models show that these data can serve as an accurate database for Monte Carlo simulations and other kinds of charged particle transport calculations. The new database was used to calculate the spatial distributions of: (i) the deposited energy by δ-electrons which are ejected by protons, (ii) the distances (from the ion trace) of holes and stopped electrons created in the ionization process and (iii) the separation between holes and electrons. These distributions have been used for the calculation of track-effect-parameters like the restricted LET and the mean prompt (transient) electrical field potentials. In addition to these “meanvalue” characteristics, we calculated the straggling of the ion energy-deposition, which is an important parameter in characterizing the process of single event upset. Similar data were obtained for electrons with energies up to 10 keV. The calculated results are presented in a form which is suitable for various applications, like: microdosimetry, upset events in microelectronics, dose equivalence and others.

A universal and competitive compact AMS facility

Abstract: The 600 kV AMS facility at ETH/PSI has been upgraded to a universal platform for AMS at low energies allowing to perform studies of 10Be, 14C, 26Al, 41Ca, 129I, 236U and Pu. The most significant improvement in performance is due to a new gas ionisation chamber of much better energy resolution. Performance for 10Be, 14C, 26Al, 129I and Pu isotopes is now competitive with larger AMS facilities. The background in 41Ca measurements is sufficiently low to measure samples for biomedical applications.

Gamma ray computed tomography to evaluate wetting/drying soil structure changes

Abstract: Wetting and drying (W–D) cycles can cause strong modifications of the structure of a soil, especially in pore distribution, which reflects the temporal and spatial distribution of soil water and, consequently, these processes can affect soil water and nutrient retention and movement. These alterations have important practical consequences when calculating soil water storages and matric potentials, widely used in irrigation management. The present paper has as objective to use gamma ray computed tomography (GCT) as a tool to investigate possible modifications in soil structure induced by W–D cycles and to analyze how these alterations can affect soil water retention. The GCT scanner used was a first generation system with a fixed source–detector arrangement, with a radioactive gamma ray source of 241Am. Soil samples were taken from profiles of three different soils characterized as Xanthic Ferralsol (Fx), Eutric Nitosol (Ne) and Rhodic Ferralsol (Fr). Eighteen samples (50 cm3), six from each soil, were submitted to none (T0), three (T1) and nine (T2) wetting/drying cycles. Based on image analysis it was possible to detect modifications in soil structure in all samples after wetting/drying cycles for all treatments. Tomographic unit profiles of the samples permitted to identify an increase on soil porosity with the increase in the number of wetting/drying cycles and it was also possible to quantify the average porosity values. The statistical test (Duncan test) indicates that there are significant differences between treatments for all samples at the 5% significance level.

Radiation-induced and sonochemical degradation of chitosan as a way to increase its fat-binding capacity

Abstract: Three physical methods of chitosan degradation: irradiation in dry state, irradiation in aqueous solution and sonication in aqueous solution were tested and compared in the terms of yields and side effects. The influence of average molecular weight of chitosan in its fat-binding ability in vitro has been studied by using a biopharmaceutical model of digestive tract. It was found that reduction in molecular weight leads to a significant increase in the amount of fat bound by 1 g of chitosan. Thus, radiation- or sonochemical treatment may be useful in improving fat-binding properties of chitosan as an active component of dietary food additives.

Radiochemical ageing of EPDM elastomers.. 2. Identification and quantification of chemical changes in EPDM and EPR films γ-irradiated under oxygen atmosphere

Abstract: This paper is devoted to the identification and quantification of the main chemical changes resulting from the radiochemical ageing under oxygen atmosphere of ethylene-propylene-diene monomer (EPDM) and ethylene-propylene rubber (EPR) films containing the same molar ratio of ethylene/propylene. IR and UV–Vis analysis showed that radiooxidation produces a complex mixture of different products and provokes the consumption of the diene double bond. The radiochemical yields of formation of ketones, carboxylic acids, hydroperoxides and alcohols were determined by combining IR analysis with derivatisation reactions and chemical titration. The contributions of secondary and tertiary structures of these two types of –OH groups were separated. Esters and γ-lactones were formed in low concentration. The oxidation products distribution in irradiated films was determined by micro-FTIR spectroscopy. Crosslinking was evaluated by gel fraction methods. In complement, the gas phase composition was analysed by mass spectrometry.

Kalypso: a software package for molecular dynamics simulation of atomic collisions at surfaces

Abstract: A suite of graphically-oriented computer programs (Kalypso) has been developed for molecular dynamics simulations of projectile collisions with metallic targets. The features of the package include free-boundary or periodic targets, many-body potentials, a variety of inelastic loss models, and the ability to carry out simulations of fluence-dependent processes.

An accurate semi-empirical equation for sputtering yields, II: for neon, argon and xenon ions

Abstract: A new general, predictive semi-empirical equation for the sputtering yields of mono-elemental solids, using 250–10,000 eV ions incident normally on the surface, has been developed. This equation is based on the approach of Matsunami et al. but includes a new atomic density term and avoids their arbitrary Q term. By analysing published experimental data for Ne, Ar and Xe sputtering yields, the accuracy of this approach may be evaluated. The standard deviations of the data for Ne, Ar and Xe are 14%, 9% and 14%, respectively and represent a very significant improvement on the semi-empirical approaches of Matsunami et al. and of Yamamura and Tawara. General predictive relationships are established to allow the approach to be used for any incident ions, however, it is expected that accuracies for low reactivity (inert gas) incident ions with masses in the range from Ne to Xe will be comparable to the above figures but extrapolation to lighter elements than Ne or heavier than Xe, or to reactive primary ions, should be treated with considerable caution.

High energy ion beam irradiation of polymers for electronic applications

Abstract: Ion irradiation of polymers offers a number of interesting possibilities for applications. In the case of latent tracks, radiochemical changes, phase transitions, alterations of the intrinsic free volume, or radiation induced defects can be exploited – the latter ones to trap mobile impurities. These approaches are useful to form, e.g. new types of sensors. Apart from this, etched tracks in polymers offer a vast range of possibilities. Practically any material – including colloides and nanocrystals – can be inserted into these pores to form nanowires or nanotubules. Sequential deposition can be made as well in radial as axial direction to form complex nanostructures. Combination with lithography enables one to form different types of novel transistors, microcapacitors, -magnets, -transformers and -sensors. Also sterilizing foils for medicine and packing industry have been made in this way. A number of new ideas are presented how to proceed further in this field. 2005 Published by Elsevier B.V.