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In continuation to our earlier studies related to energy loss and associated straggling for swift heavy ions which are generally considered as first and second order moments, respectively, in the present study, we have developed a method for the determination of skewness (third-order moment) in the energy loss distribution of the transmitted ions. In this article, the results of our measurements and their interpretation related to skewness for swift heavy ions coveringZ=6−16 with maximum values of fractional energy loss (ΔE/E) upto 75% in polyethylene napthalate polymeric foils have been presented. [ABSTRACT FROM AUTHOR]

Resistance switching (RS) properties of nanostructured In2O3films grown on Pt bottom electrode have been investigated for non-volatile memory applications. Ag/In2O3/Pt/Si layers were fabricated by pulsed laser deposition and e-beam evaporation techniques. Identical samples were irradiated by 100 MeV Li+3ions with fluence values ranging from 1×1011to 5×1013 ions/cm2at the MS beam line of Inter University Accelerator Centre, New Delhi. There was not much discrepancy found in atomic force microscopy and GIXRD for unirradiated and irradiated samples of In2O3. TypicalI–Vcharacteristics were recorded using the two-wire technique on unirradiated and irradiated Ag/In2O3/Pt/Si stack-geometry at room temperature. The hysteresis loops in theI–Vcurves were seen for the pristine device, suggesting the low-resistance state and high-resistance state in the sample. The RS ratio (Ron/Roff) of the order of 72% was estimated at room temperature. On the other hand, rectifyingI–Vcurves were traced for sample irradiated by 1×1012 ions/cm2100 MeV Li+3ions. A general mechanism of the influence of swift heavy ion irradiation on RS of Ag/In2O3/Pt/Si heterostructures has been studied. [ABSTRACT FROM AUTHOR]

Epitaxial AlGaN/GaN layers grown by molecular beam epitaxy (MBE) on SiC substrates were irradiated with 150 MeV Ag ions at a fluence of 5×1012 ions/cm2. The samples used in this study are 50 nm Al0.2Ga0.8N/1 nm AlN/1 μ m GaN/0.1 μ m AlN grown on SI 4H-SiC. Rutherford backscattering spectrometry/channeling strain measurements were carried out on off-normal axis of irradiated and unirradiated samples. In an as-grown sample, AlGaN layer is partially relaxed with a small tensile strain. After irradiation, this strain increases by 0.22% in AlGaN layer. Incident ion energy dependence of dechanneling parameter shows E 1/2 dependence, which corresponds to the dislocations. Defect densities were calculated from the E 1/2 graph. As a result of irradiation, the defect density increased on both GaN and AlGaN layers. The effect of irradiation induced-damages are analyzed as a function of material properties. Observed results from different characterization techniques such as RBS/channeling, high-resolution XRD and AFM are compared and complemented with each other to deduce the information. Possible mechanisms responsible for the observations have been discussed in detail. [ABSTRACT FROM AUTHOR]

Resistive random access memory is one of the candidate technologies for the promising next generation non-volatile memories with fast switching speed, low power consumption and non-destructive readout. The swift heavy ion (SHI)-induced resistive switching behavior of Ag/La0.7Sr0.3MnO3/Ag planar structures, grown on SiO2 substrates by the chemical solution deposition technique, has been investigated. Five identical samples were irradiated by 100 MeV Ag7+ ions with fluence values ranging from 1×1011 to 5×1013 ions/cm2 at the Materials Science beamline of the IUAC, New Delhi. Upon irradiation, systematic amorphization and grain elongation was observed in the grazing incidence X-ray diffraction and atomic force microscopy, respectively. Four-terminal I-V curves indicate typical non-ohmic behavior of pristine Ag/La0.7Sr0.3MnO3/Ag planar geometry at room temperature for several voltage-sweeping cycles. On the other hand, well-defined hysteresis loops with sharp on-off transition in the I-V curves were observed for the sample irradiated with 100 MeV Ag7+ ions at 1×1012 ions/cm2, indicating that the sample possesses low resistance state and high resistance state. A symmetrical resistance ratio (Rhigh/Rlow) of ∼ 330% at-1.7 V has been achieved. The resistance switching is bipolar and may be attributed to SHI-induced defects in the device. Such defect-induced resistive switching has recently been proposed theoretically, and our results are direct evidence of the phenomenon. [ABSTRACT FROM AUTHOR]

In the present study, we report the modification of pulsed laser deposited c-axis oriented thin films of YBa2Cu3O7-y (YBCO) in a cylindrical region around the path of swift heavy ions (SHIs). Our in situ temperature-dependent resistivity measurement and in situ low-temperature X-ray diffraction (XRD) study on YBCO irradiated at liquid nitrogen temperature with 200 MeV Ag ions shows that the SHI-induced secondary electrons selectively create point defects at CuO basal chains of YBCO. Beyond a critical fluence (∼1012 ions/cm2), the radially strained region around the amorphous latent tracks estimated from full width at half-maximum of (00l) XRD peaks tends to overlap, and a two-step superconducting transition evolves instead of a single transition in the in situ resistivity measurement. [ABSTRACT FROM AUTHOR]

Modification of the surface morphologies of titanium oxide nanoparticle thin films under swift heavy ion (SHI) irradiation was investigated using glancing angle X-ray diffractometry and atomic force microscopy. Irradiation at low ion fluences leads to grain fragmentation and a narrowing of the grain size distribution, whereas grain growth with increased average grain size and grain size distribution occur at high fluences. Associated with the change in the grain size and size distribution there occurs topological modifications at different fluences of SHI irradiation. The SHI-induced grain fragmentation, grain growth and modification of surface topography are explained by the thermal spike model of ion-matter interaction. [ABSTRACT FROM AUTHOR]

We synthesized Au nanostructures on glass by low-energy ion irradiation of a thin Au film. The Au films, deposited on a glass substrate, were irradiated by 50 keV Si- ions with different fluences. The UV-vis absorption spectroscopy of irradiated samples indicates the surface plasmon resonance peak, which is a signature of the formation of Au nanostructures. The surface morphology of the films has been characterized by atomic force microscopy, which supports the UV-vis spectroscopy findings. The metal content or the film thickness of the samples, as measured by Rutherford backscattering spectroscopy, decreased with increasing fluence, showing sputtering by ion irradiation and tailing in the lower energy edge with irradiation, revealing recoil implantation. The formation of Au nanostructures by this method can be explained on the basis of an interplay between surface instability due to ion beam sputtering and surface diffusion. [ABSTRACT FROM AUTHOR]

A Nickel Dimethylglyoxime (Ni-DMG) compound was dispersed in polymethyl methacrylate (PMMA) films at different concentrations. PMMA was synthesized by a solution polymerization technique. These films were irradiated with 120 MeV Ni10+ ions at the fluences of 1×1011 and 1×1012 ions/cm2. The radiation induced changes in dielectric properties and average surface roughness were investigated by using an LCR meter in the frequency range 50 Hz to 10 MHz and atomic force microscopy (AFM), respectively. The electrical properties of irradiated films are found to increase with the fluence and also with the concentration of Ni-DMG. From the analysis of frequency, f, dependence of dielectric constant, ε, it has been found that the dielectric response in both pristine and irradiated samples obey the Universal law given by ε α f n-1. The dielectric constant/loss is observed to change significantly due to the irradiation. This suggests that ion beam irradiation promotes (i) the metal to polymer bonding (ii) convert the polymeric structure in to hydrogen depleted carbon network due to the emission of hydrogen gas and/or other volatile gases. Atomic force microscopy (AFM) shows that the average surface roughness and surface morphology of irradiated films are observed to change. [ABSTRACT FROM AUTHOR]

Blisters formation on the surface of kapton film has been observed due to 50 MeV Li3+ ion irradiation up to the fluence of 1.04 x 1013 ions/cm² at ambient temperature. This investigation provides a foundation for a quantitative evaluation of the FTIR results for thermally stable polymer on the chemical bond deterioration with irradiation fluences. The blistering mechanism is correlated with the internal gases (CO, H2) released due to Li3+ ion induced radiation damage. The Vicker's micro-hardness testing has been carried out to study the mechanical behavior of irradiated films at room temperature. It is observed that the true hulk hardness of the film was obtained at loads greater than 400 mN. The hardness of the film increases significantly as fluence increases. [ABSTRACT FROM AUTHOR]

Conversion Electron Mössbauer Spectroscopy (CEMS) was employed in order to study the mixing induced by swift Au and Ag ions at the Fe/Si interface in the Fe/Fe57/Si system. An increase in the amount of mixing with ion fluence and electronic energy loss ( Se) has been observed. Atomic Force Microscopy (AFM) results provided indirect evidence to support the above observations. [ABSTRACT FROM AUTHOR]

Abstract. Single crystals of the amino acid benzoyl glycine (hippuric acid) are irradiated normal to the as-grown surface by highly charged Bi ions with a kinetic energy of 2.38 GeV and a fluence of 1 x 10[sup 10] ions/cm[sup 2]. The projectiles create circular craters with a mean diameter of 40 (10) nm on the surface of the crystal as observed by scanning force microscopy (SFM). The mean depth amounts to 4 (1)nm, this value being considered as a lower limit due to the finite radius of curvature of the force cantilever tip. Thus, on the average, each single-ion projectile seems to eject about 10[sup 4] molecules. On the surface of non-irradiated crystals, SFM reveals terraces of a few monolayers in height. In water, it was possible to visualize the lattice periodicity. Terraces were also observed on the irradiated crystal surface in the presence of the craters, indicating that the crystal is still intact at the given dose. [ABSTRACT FROM AUTHOR]

Measurements were carried out to deduce the transverse kinetic energies of highly charged argon recoil ions produced in single collisions of 120 MeV ions with argon atoms in which the post collision charge states of the projectiles were not determined. A time of flight spectrometer was designed and fabricated to detect the charge states of recoils. Experimental procedures for optimizing the spectrometer for extraction, transmission and detection of recoils are described. A simple approach for determining the transverse kinetic energy of the recoil ions from FWHM of the peaks is reported. This method is shown to be independent of the choice of collision partners and requires only the knowledge of the physical values of “optimized parameters” of time-of-flight spectrometer used in the experiment. The transverse kinetic energy of the recoil ions determined from the present approach is found to vary from 0.03 eV for to 4.02 eV for Ar10+. These values are compared with the results reported by earlier workers and are shown to follow a q2-behaviour up to a charge state q =8+ of the recoil ions. [ABSTRACT FROM AUTHOR]

Investigates the depth profile of implanted species of light mass elements with a detector telescope. Description of the elastic recoil detection analysis (ERDA) technique; Reasons why the technique can lead to misleading results; Accurate profiling of implanted specimen.

A letter of retraction offered by Shashi Chawla concerning the results of an experiment on swift nickel ions that were grafted with glycidyl methacrylate (GMA) using benzoyl peroxide as chemical initiator, which was published in "Polymer Engineering and Science" is presented.

Abstract. The surface morphology of thin (60 nm) Fe films irradiated with 243 MeV Au ions has been investigated using atomic force microscopy (AFM). The surface roughness was increased by the ion irradiation. The changes in the Fe content during ion irradiation were monitored by ERDA. A large area position-sensitive telescope detector with kinematic correction was used. The measurement showed that there was no change in the film thickness. This rules out the possibility of sputtering from the surface, within the sensitivity of the detection setup. Moreover, from the calculated sputter yield less than one monolayer sputtering can be expected for the applied dose. Therefore the present work shows that the increased surface roughness is due to the rearrangement of the atoms on the surface of the film. The reordering of the atoms at the surface is mom likely associated with electronic excitation by the incident ions, as the energy deposition by elastic collision process is two orders of magnitude smaller than the process of electronic excitation generated by inelastic collisions. [ABSTRACT FROM AUTHOR]