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Ion Irradiation (ion + irradiation)

Distribution by Scientific Domains

Physics and Astronomy	57%
Polymers and Materials Science	28%

Selected Abstracts

Formation of Nanoislands on Conducting Poly(3,4-ethylenedioxythiophene) Films by High-Energy - Ion Irradiation: Applications as Field Emitters and Capacitor Electrodes,

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2005
J. Joo
Abstract Nanoislands have been fabricated on the surface of conducting poly(3,4-ethylenedioxythiophene) (PEDOT) films doped with poly(4-styrenesulfonate) (PSS) using high-energy (,,1,3,MeV) Cl2+ ion irradiation. Scanning electron microscopy and atomic force microscopy confirm the direct formation of nanoislands with diameters ranging from 50,to 300,nm and heights ranging from 40,to 120,nm. From our analysis, we propose that the formation of nanoislands might be due to micelle formation of the polymeric stabilizer poly(sodium 4-styrenesulfonate) (PSS-Na) surrounding the nuclei in the PEDOT/PSS via the high-energy-ion irradiation. We observe similar results for high-energy-ion irradiated polyaniline doped with PSS-Na. On using the nanoislands as nanotip emitters of a field-emission display, an increase in the current density of about five orders of magnitude is observed. Cyclic voltammetry of the PEDOT/PSS electrode with the nanoislands as the electrode shows enhanced capacitance compared with that of the PEDOT/PSS film that contains no nanostructure. [source]

Aligned Gold Nanorods in Silica Made by Ion Irradiation of Core,Shell Colloidal Particles,

ADVANCED MATERIALS, Issue 3 2004
S. Roorda
Colloidal particles with a 14,nm diameter Au core surrounded by a 72,nm thick silica shell have been irradiated with 30,MeV heavy ions. The shell deforms into an oblate ellipsoid, while the core becomes rod-shaped (aspect ratio up to 9) with the major axis along the beam. Optical extinction measurements show evidence for split plasmon bands, characteristic for anisotropic metal nanoparticles. [source]

Enhanced Crystallinity of PTFE by Ion Irradiation in a Dense Plasma Focus

PLASMA PROCESSES AND POLYMERS, Issue 2 2007
Mehboob Sadiq
Abstract Nitrogen-ion beam pulses emitted from a low-energy (1.45 kJ) Mather-type plasma focus device are used for the surface modification of PTFE polymer specimens. The specimens, placed at a fixed position, are implanted using different number of pulses. Raman spectroscopy and XRD are employed to probe the structural changes incurred during the ion implantation. Both techniques indicate that the crystalline order in the specimens increases with increasing the irradiation dose. The crystallinity degree of the irradiated specimens, as measured from the XRD data, is found to enhance monotonically from 40% to about 55%. Possible crystallinity enhancement mechanism of irradiated PTFE specimens via chain scission is discussed. [source]

Ion irradiation and reduction effect on the conductivity and optical absorption of heavily MgO-doped LiNbO3 single crystals

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005
V.F. Pichugin
Abstract The confirmation of MgNb defects in heavily MgO doped LiNbO3 single crystals were investigated through optical absorption, electrical conductivity measurements, optical spectroscopy with nanosecond time resolution, and Raman spectroscopy technique. An increase in the MgO concentration up to 10 mole% provides an essential change of the luminescence of LiNbO3, the appearance of a supplementary optical absorption band at the 1.1 eV, an alteration of the Raman spectra caused by the formation of (MgNb) defects, a shift of the edge of the supplementary optical absorption due to ion irradiation toward the shorter wavelength region as the MgO concentration increases. The effect of Ar+ ions irradiation on the conduction of the MgO doped LiNbO3 samples was studied. The important role of reduction in modification of the conducting properties of the ion-irradiated crystals was established. The increase of the MgO concentration leads to a decrease of the reduction efficiency. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Formation of Nanoislands on Conducting Poly(3,4-ethylenedioxythiophene) Films by High-Energy - Ion Irradiation: Applications as Field Emitters and Capacitor Electrodes,

Raman spectroscopy of ion-irradiated astrophysically relevant materials

JOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2008
G. A. Baratta
Abstract Solid objects in space (interstellar grains, comets, interplanetary dust particles, etc.) are continuously exposed to energetic processes, such as cosmic ion irradiation, that influence their evolution. In this paper we present an experimental study, carried out by Raman spectroscopy, of the effects induced by ion irradiation on frozen ices and refractory materials. If the irradiated ice mixture contains a relevant amount of carbon atoms, the ice is converted into an organic residue (stable at room temperature), which at high irradiation dose evolves toward a hydrogenated amorphous carbon. Here we show that material similar to that produced in the laboratory by ion irradiation of frozen ice mixtures and refractory materials can be formed in space by cosmic ion irradiation. This finding has been recently confirmed by the Stardust mission, which revealed in some of the cometary particles collected in space and returned to earth carbonaceous materials that have been processed by cosmic ion irradiation. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Silver nanocluster containing diamond like carbon

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2008
F. Schwarz
Abstract Applying Diamond Like Carbon (DLC) as medical coating has become well established since large scale plasma processes like Plasma Immersion Ion Implantation and Deposition (PIII&D) are available. Now the focus of research lies on systematic modification of certain biological relevant properties and the most recent field of interest turned to generating antimicrobial behaviour. This is desirable for medical tools as well as for different types of medical implants. Since silver and copper are known to provide a bactericidal effect, one tries to introduce clusters of these noble metals into the carbon matrix. The basic principle of the method presented is to convert a metal containing polymer film into DLC by ion bombardment. In this paper the hydrogenated DLC matrix is characterized and the evolution of the metal particles is studied. By means of film composition (RBS/ERD), bonding structure (Raman spectroscopy) and hardness (nanoindentation), the dependency of these material properties on ion species, energy and fluence is investigated. TEM imaging is used to visualize the film structure. Upon ion irradiation of the polymer films, increased density and considerable loss of hydrogen can be observed, which both are controlled by ion fluence and mass. The crosslinking of the carbon network, caused by hydrogen drive out as well as atomic displacements in collision cascades, results in the formation of a-C:H. The silver particles in the film some ion induced growth, but still remain as nanoclusters in the a-C:H matrix. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Variation of electrical resistance in metallic glasses subjected to 130 MeV 28Si ion irradiation

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2004
H. Narayan
Abstract The change in the electrical resistivity of 2605SC (Fe81B13.5Si3.5C2) and 2705M (Co69B12Si12Fe4Mo2Ni1) metallic glasses (MGs) resulting from 130 MeV 28Si ion irradiation has been investigated. Resistivity as a function of temperature has been measured off-line and in situ before and after irradiation, and on-line as a function of ion fluence. The results show that for the 2605SC MG electrical resistivity increases by 5.2% (fluence = 3.7 × 1014 ions/cm2) and 4.5% (fluence = 1.6 × 1014 ions/cm2). This has been explained on the basis of the ,two-hit model'. For the 2705M MG, however, an unexpected decrease of electrical resistivity of about ,9.6% (fluence = 1.1 × 1016 ions/cm2) and ,8.7% (1.3 × 1014 ions/cm2) is observed, which has been attributed to irradiation-induced structural modification. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Simulation of dc conductance of two-dimensional heterogeneous system: application to carbon wires made by ion irradiation on polycrystalline diamond

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2006
N. A. Poklonski
Abstract A percolation model of two-dimensional heterogeneous system composed of two conductive phases and a method for calculating the macroscopic electric conductance of such a system in direct current regime is proposed. The parameters of the model are its geometrical dimensions, the conductance of the two phases and the relative fractions of the phases in the system. The model satisfactorily describes the non-linear dependence on width of conductance of the carbon nano- and microwires made on polycrystalline diamond surface by focused ion beam irradiation. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Density change of ion irradiated polystyrene studied by positron annihilation and SAICAS

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2007
F. Saito
Abstract Ion-irradiated polystyrene was investigated using positron annihilation DBS, AFM and SAICAS. SAICAS revealed effective crosslink formation and molecular chain scission. Due to efective crooslink formation, the subsidence of the surface hardly produced as shown in the AFM image. From positron annilation and SAICAS, the density of the irradiated layer was estimated to be 0.8 and 0.6 g/cm3 for the ion irradiation of fluence 5×1015 and 1×1016 ions/cm2, respectively, while the density of the as received sample was 1.02 g/cm3. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]