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1

Photoluminescence character of Xe ion irradiated sapphire  

NASA Astrophysics Data System (ADS)

In the present work the photoluminescence (PL) character of sapphire implanted with 180 keV Xe and irradiated with 308 MeV Xe ions was studied. The virgin, implanted and irradiated samples were investigated by PL and Fourier transform infrared (FTIR) spectra measurements. The obtained PL spectra showed the maximum emission bands at 2.75, 3.0 and 3.26 eV for the implanted fluence of 1.0 × 10 15 ions/cm 2 and at 2.4 and 3.47 eV for the irradiated fluence of 1.0 × 10 13 ions/cm 2. The FTIR spectra showed a broaden absorption band between 460 and 630 cm -1, indicating that strong damaged region formed in Al 2O 3.

Yin, Song; Xie, Er-qing; Zhang, Chong-hong; Wang, Zhi-guang; Zhou, Li-hong; Ma, Yi-Zhong; Yao, Cun-feng; Zang, Hang; Liu, Chun-bao; Sheng, Yan-bin; Gou, Jie

2008-06-01

2

Teflon impregnated anatase TiO2 nanoparticles irradiated by 80 keV Xe+ ions  

NASA Astrophysics Data System (ADS)

We report the effect of 80 keV Xe+ ion irradiation on the morphological and optical responses of TiO2 nanoparticles spread over commercially available polytetrafluoroethylene (PTFE, Teflon). These nanoparticles were synthesized via a convenient, sol-gel approach with titanium isopropoxide as the main precursor. From X-ray diffraction (XRD) studies we found that, the nanoparticles crystallize in anatase phase and with a preferential orientation of crystallites along (1 0 1) plane. Upon irradiation at a fluence of 1.25 × 1017 ions/cm2, the nanoparticle dimension was found to increase from a value of ˜9 nm to ˜20-30 nm. Essentially, particle growth is predicted as a consequence of swelling behavior accompanied by the formation of Xe van der Waal crystals in isolated regions of nano-titania. Evidence of nanoripples was also witnessed on the surface of the irradiated nano-titania. The morphological evolution was assessed both by atomic force and transmission electron microscopies (AFM and TEM) independently. From the UV-Vis optical absorption studies, the estimated optical band gap was found to drop with increasing fluence, while refractive index exhibited a remarkable improvement. Photoluminescence (PL) studies have revealed that, the band edge emission and those due to the self trapped excitons (STE) and other oxygen vacancy related ones were manifested considerably as a result of Xe ion irradiation.

Khanam, Rizwin; Paul, Nibedita; Kumar, P.; Kanjilal, D.; Ahmed, Gazi A.; Mohanta, Dambarudhar

2014-10-01

3

Anisotropic deformation of Au nanoparticles by highly charged ion Xe21+ irradiation  

NASA Astrophysics Data System (ADS)

We present a detailed study of the deformation of Au nanoparticles (NPs) caused by the irradiation of highly charged ions (HCIs). When spherical Au NPs with a diameter of 19.8 nm were irradiated by 1 MeV Xe21+ ions with a fluence of 2 × 1014 cm-2, their anisotropic deformation was observed by atomic force microscopy. The results show that spherical Au NPs expand perpendicular to the ion beam changing their shape to oblate ellipsoidal. The size aspect ratio (major over minor axis) of the observed deformed Au NPs is about 1.23. The deformation process is described by a viscoelastic thermal spike model. The HCI beam deformation technique provides a unique method to tailor the shape of noble metal NPs.

Liu, Xueliang; Xu, Zhongfeng; Zhao, Yongtao; Liu, Lili; Wang, Yuyu; Chen, Liang; Li, Dehui; Zeng, Lixia; Zhao, Di; Xiao, Guoqing

2013-09-01

4

Tetragonal WSi2 formation by 0.5-5 MeV Xe-ion-beam irradiation at 250 °C and 450 °C  

NASA Astrophysics Data System (ADS)

We studied two-step tungsten-silicidation processes, which consist of low-energy W implantation followed by high-energy Xe irradiation. The formation of silicides was studied by Rutherford backscattering spectroscopy, x-ray diffraction and transmission electron microscopy. The formed silicide layer is richer in Si than that formed by thermal annealing. The transformation from the hexagonal to tetragonal (usually formed by thermal annealing above 600 °C) WSi2 phase occurred and a tetragonal WSi2 layer was successfully formed by 1-MeV Xe+ and 5-MeV Xe++ ion irradiation at under irradiation temperatures of 410 and 450 °C. The transformation did not occur by 0.5-MeV Xe+ ions at the same substrate temperature. The tetragonal phase was also observed after irradiation by 1-MeV Xe+ at 250 °C. The phase transformation rate normalized to the nuclear energy deposition density En increases with the electronic energy deposition density Ee. This fact indicates that the phase transformation is enhanced by the inelastic electronic scattering of high-energy ion irradiation. The irradiation temperature dependence of the phase transformation was also studied. The mechanism of the silicidation by elastic nuclear scattering and that of the phase transformation by inelastic electronic scattering of high-energy heavy-ion-beam irradiation are qualitatively discussed.

Yamaguchi, Toru; Nakata, Jyoji

1997-03-01

5

Damage Accumulation in MgAl{sub 2}O{sub 4} and Yttria-Stabilized ZrO{sub 2} by Xe-Ion Irradiation  

SciTech Connect

Magnesium-aluminate spinel (MAS) and yttria-stabilized zirconia (YSZ) are being considered for use as ceramic matrices in proliferation resistant fuels and radioactive storage systems, and may be used either as individual entities or as constituents in multicomponent ceramic systems. It is worthwhile, therefore, to compare radiation damage in these two potentially important materials when subjected to similar irradiation conditions, e.g., ion beam irradiation. To compare radiation damage properties of these two materials, single crystals of spinel and zirconia were irradiated with 340 keV Xe{sup ++} ions at 120 K, and subsequently investigated by Rutherford backscattering and ion channeling (RBS/C), and optical absorption spectroscopy. Results indicate that damage accumulation in both spinel and zirconia follow a three stage process: (1) very slow damage accumulation over a wide range of dose; (2) rapid changes in damage over a range of doses from about 0.25 to 25 displacements per atom (DPA); (3) slower damage accumulation at very high doses and possibly saturation. Optical absorption results indicate that F-centers form in Xe ion-irradiated spinel and that the concentration of these centers saturates at high dose. Absorption bands are also formed in both spinel and zirconia that are due to point defect complexes formed upon irradiation. These bands increase in intensity with increasing Xe dose, and, in the case of zirconia, without saturation. Finally the rate of change in intensity of these bands with increasing Xe dose, mimic the changes in damage observed by RBS/C with increasing dose.

Afanasyev-Charkin, I.V.; Gritsyna, V.T.; Cooke, D.W.; Bennett, B.L.; Sickafus, K.E.

1999-04-25

6

Toward over unity proton sputtering yields from a hydrogen-terminated Si(111) 1×1 surface irradiated by slow highly charged Xe ions  

Microsoft Academic Search

The emission of sputtered ions from a hydrogen-terminated Si(111) 1×1 surface has been measured for impact of slow (v<0.25vBohr) highly charged Xe ions. Proton sputtering yields increase strongly with projectile charge q (qgammagamma~4) and reach to the value greater than one for Xeq+ impact (q>=44). Yields of Si+ remain constant (~0.1) for lower q (14<=q<=29) but increase with q for

Satoshi Takahashi; Masahide Tona; Kazuo Nagata; Nobuyuki Nakamura; Nobuo Yoshiyasu; Chikashi Yamada; Shunsuke Ohtani; Makoto Sakurai

2005-01-01

7

The studies of irradiation assisted stress corrosion cracking on reactor internals stainless steel under Xe irradiation  

NASA Astrophysics Data System (ADS)

Specimens of Chinese domestic reactor internals stainless steel were irradiated with 6 MeV Xe ions for three peak displacement damage of 2, 7 and 15 dpa at room temperature. The slow strain rate tests (SSRT), grazing incidence X-ray diffraction (GIXRD) and nano-indentation tests were carried out to study the IASCC properties, phase transition and nano-hardness variations. The SSRT results indicate that the IASCC susceptibility increases with irradiation damage. Ion irradiation accelerates the stress corrosion cracking (SCC). A new ferrite phase diffraction peak of ?(1 1 0) after irradiated to 7 dpa and another two ? phase of ?(2 0 0) and ?(2 1 1) after irradiated to 15 dpa were observed by GIXRD, which may be due to localized deformation. A similar trend of irradiation hardening and IASCC susceptibility was observed, which suggests an essential connection between them.

Wang, Rong-shan; Xu, Chao-liang; Liu, Xiang-bing; Huang, Ping; Chen, Yu

2015-02-01

8

Ion irradiation-induced anisotropic plastic deformation  

E-print Network

in silica made by ion irradiation of core-shell colloidal particles 114 9.7 Conclusions 116 Summary 118.3 This thesis 14 2 Anisotropic plastic deformation of colloidal silica particles under 4 MeV Xe ion irradiation.3.1 Silica colloids 31 3.3.2 Other materials 34 3.4 Conclusions 37 4. Ion irradiation-induced anisotropic

Polman, Albert

9

Kr and Xe irradiations in lanthanum (La) doped ceria: Study at the high dose regime  

NASA Astrophysics Data System (ADS)

In order to understand cavity and bubble formation and growth in oxide nuclear fuel materials, ion beam irradiation experiments were conducted with two common fission gas species: Kr and Xe. Ceria (CeO 2) was selected as a surrogate material for uranium dioxide (UO 2) due to its many similar properties to UO 2. Ion beam energies were chosen such that both cavities and gas bubbles structures were induced by ion irradiations. The ion irradiation experiments were carried out at 600 °C, at which temperature, cavity/gas bubble structures are believed to be immobile in this material. Lanthanum (La) was chosen as a dopant in CeO 2 to investigate the effect of impurities. The presence of La in the CeO 2 lattice also introduces a predictable initial concentration of oxygen vacancies, similar to the introduction of oxygen vacancies by the existence of Pu 3+ in MOX fuel [1]. The influence of two La concentrations, 5% and 25%, were examined. The study focused on the high dose regime where cavity/gas bubble structures were clearly identifiable with their sizes and number densities readily measurable. Cavity/gas bubble coarsening by coalescence was identified with TEM (Transmission Electron Microscopy) characterizations of as-irradiated La doped CeO 2 specimens. The results revealed that lanthanum trapping has significant influence on the cavity/bubble growth in the material lattice by comparing the cavity/gas bubble size distributions between 5% La doped ceria and 25% La doped ceria. Lattice and kinetic Monte Carlo calculations described in a previous work have provided insights to the interpretations of the experimental results [2]. Solid state Xe precipitates were observed in low energy Xe implantation in 5% La doped ceria to a very high fluence of 1 × 10 17 ions/cm 2 at 600 °C. The solid state Xe precipitate structures are represented by faceted morphology. Very similar observations of solid state/near solid state Xe bubbles were made by Nogita et al. in the outer region of UO 2 pellet irradiated to a pellet average burnup of 49 GWd/t [3].

Yun, Di; Oaks, Aaron J.; Chen, Wei-ying; Kirk, Marquis A.; Rest, Jeffrey; Insopov, Zinetula Z.; Yacout, Abdellatif M.; Stubbins, James F.

2011-11-01

10

Sputtering of Au induced by single Xe ion impacts  

SciTech Connect

Sputtering of Au thin films has been determined for Xe ions with energies between 50 and 600 keV. In-situ transmission electron microscopy was used to observe sputtered Au during deposition on a carbon foil near the specimen. Total reflection and transmission sputtering yields for a 62 nm thick Au thin film were determined by ex-situ measurement of the total amount of Au on the carbon foils. In situ observations show that individual Xe ions eject Au nanoparticles as large as 7 nm in diameter with an average diameter of approximately 3 nm. Particle emission correlates with crater formation due to single ion impacts. Nanoparticle emission contributes significantly to the total sputtering yield for Xe ions in this energy range in either reflection or transmission geometry.

Birtcher, R. C.; Donnelly, S. E.

1999-12-06

11

Microstructure evolution in Xe-irradiated UO2 at room temperature  

SciTech Connect

In situ Transmission Electron Microscopy was conducted for single crystal UO2 to understand the microstructure evolution during 300 keV Xe irradiation at room temperature. The dislocation microstructure evolution was shown to occur as nucleation and growth of dislocation loops at low irradiation doses, followed by transformation to extended dislocation segments and tangles at higher doses. Xe bubbles with dimensions of 1-2 nm were observed after room-temperature irradiation. Electron Energy Loss Spectroscopy indicated that UO2 remained stoichiometric under room temperature Xe irradiation.

L.F. He; J. Pakarinen; M.A. Kirk; J. Gan; A.T. Nelson; X.-M. Bai; A. El-Azab; T.R. Allen

2014-07-01

12

Microstructure and nanoindentation of the CLAM steel with nanocrystalline grains under Xe irradiation  

NASA Astrophysics Data System (ADS)

This work presents an early look at irradiation effects on China low activation martensitic (CLAM) steel with nanocrystalline grains (NC-CLAM steels) under 500 keV Xe-ion bombardment at room temperature to doses up to 5.3 displacements per atom (dpa). The microstructure in the topmost region of the steel is composed of nanocrystalline grains with an average diameter of 13 nm. As the samples were implanted at low dose, the nanocrystalline grains had martensite lath structure, and many dislocations and high density bubbles were introduced into the NC-CLAM steels. As the irradiation dose up to 5.3 dpa, a tangled dislocation network exists in the lath region, and the size of the bubbles increases. X-ray diffraction results show that the crystal quality decreases after irradiation, although the nanocrystals obviously coarsen. Grain growth under irradiation may be ascribed to the direct impact of the thermal spike on grain boundaries in the NC-CLAM steels. In irradiated samples, a compressive stress exists in the surface layer because of grain growth and irradiation-introduced defects, while the irradiation introduced grain-size coarsening and defects gradients from the surface to matrix result in a tensile stress in the irradiated NC-CLAM steels. Nanoindentation was used to estimate changes in mechanical properties during irradiation, and the results show that the hardness of the NC-CLAM steels increases with increasing irradiation dose, which was ascribed to the competition between the grain boundaries and the irradiation-introduced defects.

Chang, Yongqin; Zhang, Jing; Li, Xiaolin; Guo, Qiang; Wan, Farong; Long, Yi

2014-12-01

13

Energy levels and radiative rates for transitions in B-like to F-like Xe ions (Xe L-XLVI)  

SciTech Connect

Energy levels, radiative rates, oscillator strengths, line strengths, and lifetimes have been calculated for transitions in B-like to F-like Xe ions, Xe L-XLVI. For the calculations, a fully relativistic GRASP code has been adopted, and results are reported for all electric dipole, electric quadrupole, magnetic dipole, and magnetic quadrupole transitions among the lowest 125, 236, 272, 226, and 113 levels of Xe L, Xe XLIX, Xe XLVIII, Xe XLVII, and Xe XLVI, respectively, belonging to the n {<=} 3 configurations.

Aggarwal, K.M. [Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom)], E-mail: K.Aggarwal@qub.ac.uk; Keenan, F.P. [Astrophysics Research Centre, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom); Lawson, K.D. [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)

2010-03-15

14

Zirconium oxidation under high energy heavy ion irradiation N. Brerd, A. Chevarier, N. Moncoffre, H. Jaffrezic,  

E-print Network

Zirconium oxidation under high energy heavy ion irradiation N. Bérerd, A. Chevarier, N. Moncoffre This paper concerns the study of zirconium oxidation under irradiation with high energetic Xe ions oxidation data. 1 #12;I. INTRODUCTION This paper deals with the influence of heavy ion irradiation

Paris-Sud XI, Université de

15

Dose dependence of the production yield of endohedral 133Xe-fullerene by ion implantation  

NASA Astrophysics Data System (ADS)

The production yield of endohedral 133Xe-fullerene by ion implantation has been studied by taking advantage of the radioactivity of 133Xe. Fullerene targets, which were produced by vacuum evaporation of C 60 or C 70 on a Ni backing, were bombarded with 30-38 keV 133Xe ions by using an isotope separator at doses ranging from 1 × 10 12 to 1 × 10 14 cm -2. The production yield of endohedral 133Xe-fullerene was determined by an high performance liquid chromatography analysis following the dissolution of the targets in o-dichlorobenzene. It was found that the production yield decreased with increasing dose and incident energy, and the production yield of 133Xe@C 70 was higher than that of 133Xe@C 60 for the same dose and incident energy. Those production yields are discussed in connection with amorphization of fullerene molecules in collisions with 133Xe ions.

Watanabe, S.; Ishioka, N. S.; Shimomura, H.; Muramatsu, H.; Sekine, T.

2003-05-01

16

Structural investigation of xenon-ion-beam-irradiated glassy carbon  

Microsoft Academic Search

Raman spectroscopy, cross-sectional transmission electron microscopy, and electron-energy-loss spectroscopy have been used to monitor the ion-beam-induced transformation in glassy carbon irradiated with 320-keV Xe ions to doses between 5×1012 and 6×1016 ions\\/cm2. It was found that (i) the ion beam amorphizes the glassy carbon structure; (ii) the amorphization is accompanied by a compaction of the glassy carbon from an initial

D. G. McCulloch; S. Prawer; A. Hoffman

1994-01-01

17

Accurate Xe isotope measurement using JPL ion trap.  

PubMed

We report an approach for the reproducible and accurate compositional analysis of different mixtures of Xe isotopes using miniature Jet Propulsion Laboratory Quadrupole Ion Trap (JPL-QIT). A major study objective was to validate the recent instrumental improvements to the long-term operational stability under different pressures, temperatures, and trapping conditions. We propose that the present device can be used in certification of trace amounts of isotopes in mixtures dominated by one or more isotopes. Measured isotopic compositions are verified against commercially available standards with accuracy better than 0.07%. To aid the analysis of experimental data, we developed a scalable replica fitting method and use peak areas as descriptors of relative isotopic abundances. This low-power and low-mass device is ideally suited for planetary explorations aimed to enhance quantitative analysis for major isotopes present in small amounts of atmospheric samples. PMID:25216693

Madzunkov, Stojan M; Nikoli?, Dragan

2014-11-01

18

Calculation of Ion Charge State Distributions After Inner-Shell Ionization in Xe Atom  

SciTech Connect

The vacancy cascades following initial inner-shell vacancies in single and multi-ionized atoms often lead to highly charged residual ions. The inner-shell vacancy produced by ionization processes may decay by either a radiative or non-radiative transition. In addition to the vacancy filling processes, there is an electron shake off process due to the change of core potential of the atom. In the calculation of vacancy cascades, the radiative (x-ray) and non-radiative (Auger and Coster-Kronig) branching ratios give valuable information on the de-excitation dynamics of an atom with inner-shell vacancy. The production of multi-charged ions yield by the Auger cascades following inner shell ionization of an atom has been studied both experimentally and theoretically. Multi-charged Xe ions following de-excitation of K-, L{sub 1}-, L{sub 2,3}-, M{sub 1}-, M{sub 2,3}- and M{sub 4,5} subshell vacancies are calculated using Monte-Carlo algorithm to simulate the vacancy cascade development. Fluorescence yield (radiative) and Auger, Coster- Kronig yield (non- radiative) are evaluated. The decay of K hole state through radiative transitions is found to be more probable than non-radiative transitions in the first step of de-excitation. On the other hand, the decay of L, M vacancies through non-radiative transitions are more probable. The K shell ionization in Xe atom mainly yields Xe{sup 7+}, Xe{sup 8+}, Xe{sup 9+} and Xe{sup 10+} ions, and the charged X{sup 8+} ions are the highest. The main product from the L{sub 1}- shell ionization is found to be Xe{sup 8+}, Xe{sup 9+} ions, while the charged Xe{sup 8+} ions predominate at L{sub 2,3} hole states. The charged Xe{sup 6+}, Xe{sup 7+} and Xe{sup 8+} ions mainly yield from 3s{sub 1/2} and 3p{sub 1/2,3/2} ionization, while Xe in 3d{sub 3/2,5/2} hole states mainly turns into Xe{sup 4+} and Xe{sup 5+} ions. The present results are found to agree well with the experimental data.

Mohammedein, Adel M.; Ghoneim, Adel A.; Kandil, Kandil M.; Kadad, Ibrahim M. [Applied Sciences Department, College of Technological Studies, P.O. Box 42325, Shuwaikh 70654 (Kuwait)

2010-01-05

19

Surface damage on 6H-SiC by highly-charged Xeq+ ions irradiation  

NASA Astrophysics Data System (ADS)

Surface damage on 6H-SiC irradiated by highly-charged Xeq+ (q = 18, 26) ions to different fluences in two geometries was studied by means of AFM, Raman scattering spectroscopy and FTIR spectrometry. The FTIR spectra analysis shows that for Xe26+ ions irradiation at normal incidence, a deep reflection dip appears at about 930 cm-1. Moreover, the reflectance on top of reststrahlen band decreases as the ion fluence increases, and the reflectance at tilted incidence is larger than that at normal incidence. The Raman scattering spectra reveal that for Xe26+ ions at normal incidence, surface reconstruction occurs and amorphous stoichiometric SiC and Si-Si and C-C bonds are generated and original Si-C vibrational mode disappears. And the intensity of scattering peaks decreases with increasing dose. The AFM measurement shows that the surface swells after irradiation. With increasing ion fluence, the step height between the irradiated and the unirradiated region increases for Xe18+ ions irradiation; while for Xe26+ ions irradiation, the step height first increases and then decreases with increasing ion fluence. Moreover, the step height at normal incidence is higher than that at tilted incidence by the irradiation with Xe18+ to the same ion fluence. A good agreement between the results from the three methods is found.

Zhang, L. Q.; Zhang, C. H.; Han, L. H.; Xu, C. L.; Li, J. J.; Yang, Y. T.; Song, Y.; Gou, J.; Li, J. Y.; Ma, Y. Z.

2014-12-01

20

Ba-ion extraction from a high pressure Xe gas for double-beta decay studies with EXO  

E-print Network

An experimental setup is being developed to extract Ba ions from a high-pressure Xe gas environment. It aims to transport Ba ions from 10 bar Xe to vacuum conditions. The setup utilizes a converging-diverging nozzle in combination with a radio-frequency (RF) funnel to move Ba ions into vacuum through the pressure drop of several orders of magnitude. This technique is intended to be used in a future multi-ton detector investigating double-beta decay in $^{136}$Xe. Efficient extraction and detection of Ba ions, the decay product of Xe, would allow for a background-free measurement of the $^{136}$Xe double-beta decay.

T. Brunner; D. Fudenberg; A. Sabourov; V. L. Varentsov; G. Gratta; D. Sinclair; for the EXO collaboration

2013-02-27

21

Influence of Xe{sub 2}{sup +} ions on the micro-hollow cathode discharge driven by thermionic emission  

SciTech Connect

The influence of Xe{sub 2}{sup +} dimer ions and excited Xe* atoms on the hollow cathode discharge driven by electron thermionic emission is studied using two-dimensional Particle-in-Cell Monte Carlo Collisions modeling. A comparison with the results of two-component (electrons and Xe{sup +} ions) plasma modeling showed that the presence of the Xe{sub 2}{sup +} dimer ions and excited Xe* atoms in the plasma affects the plasma parameters (density, potential, and ion fluxes toward the cathode). The influence of Xe{sub 2}{sup +} ions and Xe* atoms on the plasma sheath parameters, such as thickness and the ion velocity at the sheath edge, is analyzed.

Levko, D. [LAPLACE (Laboratoire Plasma et Conversion d'Energie), Universite de Toulouse, UPS, INPT Toulouse, 118 Route de Narbonne, F-31062 Toulouse Cedex 9 (France)] [LAPLACE (Laboratoire Plasma et Conversion d'Energie), Universite de Toulouse, UPS, INPT Toulouse, 118 Route de Narbonne, F-31062 Toulouse Cedex 9 (France); Bliokh, Y. P.; Krasik, Ya. E. [Department of Physics, Technion, 32000 Haifa (Israel)] [Department of Physics, Technion, 32000 Haifa (Israel)

2014-04-15

22

Observation of hyperfine mixing in measurements of a magnetic octupole decay in isotopically pure nickel-like 129Xe and 132Xe ions  

SciTech Connect

We present measurements of high statistical significance of the rate of the magnetic octupole (M3) decay in nickel-like ions of isotopically pure {sup 129}Xe and {sup 132}Xe. On {sup 132}Xe, an isotope with zero nuclear spin and therefore without hyperfine structure, the lifetime of the metastable level was established as (15.06 {+-} 0.24) ms. On {sup 129}Xe, an additional fast (2.7 {+-} 0.1 ms) decay component was established that represents hyperfine mixing with a level that decays by electric quadrupole (E2) radiation.

Trabert, E; Beiersdorfer, P; Brown, G V

2006-12-21

23

Effect of XeCl laser irradiation on the defect structure of Nd:YAG crystals  

NASA Astrophysics Data System (ADS)

This paper presents the effect of XeCl laser irradiation on Nd:YAG single crystal samples with various number of pulses at different repetition rates and laser fluences. Effects of the irradiation on the optical and structural properties of the crystal are analyzed by UV-vis-NIR spectroscopy. Annihilation of some point defects of the crystal structure is observed following laser irradiation at a fluence of 100 mJ cm-2 with 100 and 500 pulses. Increasing the laser fluence and pulse numbers leads to saturation and new defects are found to be formed in the crystal. Additional absorption spectra of the irradiated samples show that oxygen vacancies in the Nd:YAG crystals are removed during the low-dose irradiation. The laser irradiation is compared to the thermal annealing process for Nd:YAG crystal modification. Additional absorption spectrum of an annealed sample reveals that induced negative absorption band at 236 nm is correlated with the annihilation of the oxygen vacancy center. Our results also demonstrate that XeCl laser treatment has several advantages upon annealing at high temperatures in the Nd:YAG crystal quality improvement. Thus, the present work can give a new approach to modify Nd:YAG crystals to be used in a wide variety of solid-state laser engineering.

Panahibakhsh, S.; Jelvani, S.; Maleki, M. H.; Mollabashi, M.; Abolhosseini, S.

2014-09-01

24

Precision frequency trimming of SAW and STW resonators using Xe+ heavy ion bombardment  

Microsoft Academic Search

A method for precision frequency trimming of surface acoustic wave (SAW) and surface transverse wave (STW) based resonant devices using a Xe+ heavy ion bombardment technique is described. The devices are downtrimmed in frequency in an in-situ monitoring process by means of a Kaufmann type ion source that allows first a rough and then a fine frequency trimming with an

Vladimir Shakirovich Aliev; I. D. Avramov

1994-01-01

25

Irradiation hardening of ODS ferritic steels under helium implantation and heavy-ion irradiation  

NASA Astrophysics Data System (ADS)

Irradiation hardening of ODS ferritic steels after multi-energy He-ion implantation, or after irradiation with energetic heavy ions including Xe and Bi-ions was investigated with nano-indentation technique. Three kinds of high-Cr ODS ferritic steels including the commercial MA956 (19Cr-3.5Al), the 16Cr-0.1Ti and the 16Cr-3.5Al-0.1Zr were used. Data of nano-hardness were analyzed with an approach based on Nix-Gao model. The depth profiles of nano-hardness can be understood by the indentation size effect (ISE) in specimens of MA956 implanted with multi-energy He-ions or irradiated with 328 MeV Xe ions, which produced a plateau damage profile in the near-surface region. However, the damage gradient overlaps the ISE in the specimens irradiated with 9.45 Bi ions. The dose dependence of the nano-hardness shows a rapid increase at low doses and a slowdown at higher doses. An 1/2-power law dependence on dpa level is obtained. The discrepancy in nano-hardness between the helium implantation and Xe-ion irradiation can be understood by using the average damage level instead of the peak dpa level. Helium-implantation to a high dose (7400 appm/0.5 dpa) causes an additional hardening, which is possibly attributed to the impediment of motion dislocations by helium bubbles formed in high concentration in specimens.

Zhang, Hengqing; Zhang, Chonghong; Yang, Yitao; Meng, Yancheng; Jang, Jinsung; Kimura, Akihiko

2014-12-01

26

Specific low temperature release of 131Xe from irradiated MOX fuel  

NASA Astrophysics Data System (ADS)

A particular low temperature behaviour of the 131Xe isotope was observed during release studies of fission gases from MOX fuel samples irradiated at 44.5 GWd/tHM. A reproducible release peak, representing 2.7% of the total release of the only 131Xe, was observed at ˜1000 K, the rest of the release curve being essentially identical for all the other xenon isotopes. The integral isotopic composition of the different xenon isotopes is in very good agreement with the inventory calculated using ORIGEN-2. The presence of this particular release is explained by the relation between the thermal diffusion and decay properties of the various iodine radioisotopes decaying all into xenon.

Hiernaut, J.-P.; Wiss, T.; Rondinella, V. V.; Colle, J.-Y.; Sasahara, A.; Sonoda, T.; Konings, R. J. M.

2009-08-01

27

Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I2 mixtures  

E-print Network

Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I2 mixtures Paul. We found that in time modulated discharges, the emissions from excited states of atomic iodine decays sources using a xenon/iodine gas mixture are being investigated as a multiwavelength UV lighting source

Kushner, Mark

28

Focused-ion-beam cross-sectioning techniques using XeF2  

NASA Astrophysics Data System (ADS)

We have developed an ion-assisted gas etching (IAGE) technique which enhances existing focused ion beam (FIB) failure analysis (FA) cross-sectioning techniques. Preliminary results show enhanced sputter removal rate of certain materials, decoration of material interfaces or boundaries, and preferential etching of materials particularly difficult to image with standard secondary imaging systems. In particular we show two examples of IAGE using XeF2. The first sample is a multilayer of resist on oxides through which contact holes have been made by reactive ion etching (RIE) to an implanted silicon layer. A typical FIB cross-section made without IAGE shows some delineation of boundaries between oxides and a slight cascade of the resist at the top edge of the section. An FIB section made while etching with XeF2 shows improvement in delineation of the boundaries between the oxides and in particular, decorates the implanted layer. To verify the preliminary evidence that implanted material can be selectively etched with XeF2, we used a silicon wafer implanted with As+ to a depth of 850 A, and the resist was stripped. Typical FIB sectioning could not distinguish between the implanted and nonimplanted regions on the wafer, either with scanning electron (SEM) images or scanning ion (SIM) images. However, there was a slight difference in the SIM image of the top surface of the wafer. A very low ion dose combined with XeF2 selectively etched the implanted and nonimplanted regions enough to distinguish them clearly in an SEM image. Thus we have preliminary evidence that IAGE with XeF2 complements existing FIB FA cross-sectioning techniques and has particular potential for defining boundaries of materials which typically have low contrast such as oxides, and as a way of imaging implanted regions.

Stewart, Diane K.; Vasile, Michael J.

1992-07-01

29

Effect of heavy noble gas ion irradiation on terahertz emission efficiency of InP (100) and (111) crystal planes  

NASA Astrophysics Data System (ADS)

Emission of terahertz (THz) electromagnetic radiation from heavily-doped (5 × 1018 cm-3) (100) and (111) InP bulk materials and nanoporous honeycomb membranes, irradiated with heavy noble gas (Kr and Xe) ions, is presented. Irradiating samples with Kr or Xe improves THz emission efficiency. For (111) samples, as for unirradiated samples, the irradiated porous structures generate more THz radiation than their bulk counterparts. On the other hand, in contrast to unirradiated (100) samples, the irradiated (100) samples show a decrease in THz emission with porosity. We attribute this behaviour to changes in the local electric field due to the combined effect of the irradiation and nanoporosity.

Radhanpura, K.; Lewis, R. A.; Sirbu, L.; Enachi, M.; Tiginyanu, I. M.; Skuratov, V. A.

2014-09-01

30

Evolution of Xe spectrum and ion charge under sudden incoming radiation  

NASA Astrophysics Data System (ADS)

Experiments [1] and simulations of Xe at high temperature were recently reported, due to the possible scaling of astrophysical radiative shocks [2]. We used the newest version of HULLAC [3] to compute energy levels, radiative and collisional transition rates and level populations in a Coronal Radiative Model for the ions Xe9+ to Xe44+ (36263 configurations), at electron temperature of 100 eV and electron density of 10^19 -- 10^21 e/cm^3, in the presence of an external Planckian radiation field. Static and time dependent influence of the radiation on ion charge and spectrum is described. We show an effect of shell structure on relaxation of ion charge when the radiation field is suddenly turn on.[4pt] [1] Busquet, M., Thais, F., Gonzalez, M., et al., J. App. Phys. 107, 083302 (2010).[0pt] [2] Ryutov, D., Drake, R. P., Kane, J., et al., Astrophys. J. 518, 821 (1999).[0pt] [3] Klapisch, M. and Busquet, M., High Ener. Dens. Phys. 7, 98 (2011).

Klapisch, Marcel; Busquet, Michel

2012-06-01

31

Kr II and Xe II axial velocity distribution functions in a cross-field ion source  

SciTech Connect

Laser induced fluorescence measurements were carried out in a cross-field ion source to examine the behaviour of the axial ion velocity distribution functions (VDFs) in the expanding plasma. In the present paper, we focus on the axial VDFs of Kr II and Xe II ions. We examine the contourplots in a 1D-phase space (x,v{sub x}) representation in front of the exhaust channel and along the centerline of the ion source. The main ion beam, whose momentum corresponds to the ions that are accelerated through the whole potential drop, is observed. A secondary structure reveals the ions coming from the opposite side of the channel. We show that the formation of the neutralized ion flow is governed by the annular geometry. The assumption of a collisionless shock or a double layer due to supersonic beam interaction is not necessary. A non-negligible fraction of slow ions originates in local ionization or charge-exchange collision events between ions of the expanding plasma and atoms of the background residual gas. Slow ions that are produced near the centerline in the vicinity of the exit plane are accelerated toward the source body with a negative velocity leading to a high sputtering of front face. On the contrary, the ions that are produced in the vicinity of the channel exit plane are partially accelerated by the extended electric field.

Lejeune, A.; Bourgeois, G.; Mazouffre, S. [ICARE, CNRS, 1C Avenue de la Recherche Scientifique, 45071 Orlans Cedex 2 (France)

2012-07-15

32

Coincidence measurement of electron capture processes between highly charged I[sup q+] ions and Xe atoms  

SciTech Connect

Coincidence measurement of electron capture processes between I[sup 15+] ions and Xe atoms was performed. The state dependence of autoionization probability for doubly excited ions was illustrated from the comparison of energy gain spectra between autoionized and radiatively stabilized ions.

Sakurai, M.; Tawara, H.; Yamada, I. (National Institute for Fusion Science, Nagoya 464-01 (Japan)); Kimura, M. (Department of Physics, Osaka University, Toyonaka (Japan)); Nakamura, N.; Ohtani, S. (The University of Electro-Communications, 182 (Japan)); Danjo, A. (Faculty of Science, Niigata University, Niigata 950-21 (Japan)); Yoshino, M. (Shibaura Institute of Technology, Minato, 108 (Japan)); Matsumoto, A. (Hiroshima Institute of Technology, Saeki, Hiroshima 731-51 (Japan))

1993-06-05

33

Ion-irradiation effect on high-temperature behaviors of advanced SiC fibers  

NASA Astrophysics Data System (ADS)

Heavy ion beam irradiation is usually chosen to simulate neutron irradiation damages in materials. However, there has the difficulty to study macro-properties of irradiated materials due to the very small affected depth. In this study, we have explored macro-properties of the ion-irradiated materials, owing to very fine diameter of Tyranno™-SA SiC fibers. The fibers were irradiated at a National Large Accelerator of Heavy Ions facility, GANIL (Caen, France), under 95 MeV Xe ions at room-temperature. To prevent the damage gradient in fiber, the fibers were irradiated on two sides with two fluence levels. According to TRIM-code calculation, the irradiation damages in the fibers affected the entire volume of the fibers with estimations of 0.05 and 0.2 dpa. The high-temperature behaviors of the ion-irradiated fibers from room temperature to 1200 °C were investigated by a specific tensile test device of single fiber, named MacaSiC. The thermo-elastic modulus of the ion-irradiated fibers showed the recovering, which started from 600 °C during heating. The thermo-electrical conductivity of the ion-irradiated fibers gradually increased until 900 °C and then saturated during heating and gradually decreased during cooling. The normalized value of electrical conductivity for 0.05 dpa irradiated fibers had higher than that of 0.02 dpa irradiated fibers after heating and cooling.

Shimoda, K.; Colin, C.; Kishimoto, H.; Doriota, S.

2011-10-01

34

Theoretical investigation of HNgNH3 (+) ions (Ng = He, Ne, Ar, Kr, and Xe).  

PubMed

The equilibrium geometries, harmonic frequencies, and dissociation energies of HNgNH3 (+) ions (Ng = He, Ne, Ar, Kr, and Xe) were investigated using the following method: Becke-3-parameter-Lee-Yang-Parr (B3LYP), Boese-Matrin for Kinetics (BMK), second-order Møller-Plesset perturbation theory (MP2), and coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)). The results indicate that HHeNH3 (+), HArNH3 (+), HKrNH3 (+), and HXeNH3 (+) ions are metastable species that are protected from decomposition by high energy barriers, whereas the HNeNH3 (+) ion is unstable because of its relatively small energy barrier for decomposition. The bonding nature of noble-gas atoms in HNgNH3 (+) was also analyzed using the atoms in molecules approach, natural energy decomposition analysis, and natural bond orbital analysis. PMID:25877572

Gao, Kunqi; Sheng, Li

2015-04-14

35

Ion-radical synergy in HfO2 etching studied with a XeF2/Ar+ beam setup  

NASA Astrophysics Data System (ADS)

To gain more insight into fundamental aspects of the etching behavior of Hf-based high-k materials in plasma etch reactors, HfO2 films were etched in a multiple-beam setup consisting of a low energy Ar+ ion beam and a XeF2 radical beam. The etch rate and etch products were monitored by real-time ellipsometry and mass spectrometry, respectively. Although etching of HfO2 in XeF2/Ar+ chemistry is mainly a physical effect, an unambiguous proof of the ion-radical synergistic effect for the etching of HfO2 is presented. The etch yield for 400 eV Ar+ ions at a substrate temperature of 300 °C was 0.3 atoms/ion for Ar+ sputtering and increased to 2 atoms/ion when XeF2 was also supplied. The etch yield proved to follow the common square root of ion energy dependence both for pure sputtering and radical enhanced etching, with a threshold energy at room temperature of 69±17 eV for Ar+ ions and 54±14 eV for Ar+ ions with XeF2.

Gevers, P. M.; Beijerinck, H. C. W.; van de Sanden, M. C. M.; Kessels, W. M. M.

2008-04-01

36

Formation mechanism of silver nanocrystals made by ion irradiation of Na+<-->Ag+ ion-exchanged sodalime silicate glass  

NASA Astrophysics Data System (ADS)

Sodalime silicate glass surface layers were doped with up to 7.0 at.% Ag + ions by ion-exchange in a AgNO 3/NaNO 3 solution at 330-355°C. Ion irradiation using either 400 and 500 keV He, 1 MeV Ne or 2 MeV Xe was then used to induce the growth of metallic nanocrystals in the ion-exchanged region. The ion fluences ranged from 1.3×10 14 ions/cm2 to 1.1×10 17 ions/cm2. X-ray and electron diffraction show small Ag nanocrystals with a broad size distribution, up to a diameter of 10-15 nm, after irradiation. Optical transmission measurements show the characteristic surface plasmon resonance of metallic Ag around 420 nm. The absorption resonance sharpens and increases in strength with increasing ion irradiation fluence, indicating that both nanocrystal size and volume fraction increase with irradiation fluence. Depending on ion fluence, up to ˜15% of the ion-exchanged Ag + ions is incorporated in nanocrystals. From a systematic comparison of the degree of nanocrystal formation as a function of ion species, fluence and energy, it is concluded that nanocrystal formation is mainly caused by the atomic displacement energy loss component of the incoming ion beam; the electronic energy deposition component is less efficient.

Peters, D. P.; Strohhöfer, C.; Brongersma, M. L.; van der Elsken, J.; Polman, A.

2000-06-01

37

Relativistic Many-body Moller-Plesset Perturbation Theory Calculations of the Energy Levels and Transition Probabilities in Na- to P-like Xe Ions  

SciTech Connect

Relativistic multireference many-body perturbation theory calculations have been performed on Xe{sup 43+}-Xe{sup 39+} ions, resulting in energy levels, electric dipole transition probabilities, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, frequency-dependent Breit correction and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.

Vilkas, M J; Ishikawa, Y; Trabert, E

2007-03-27

38

Effects of ion irradiation on solid oxide fuel cells  

NASA Astrophysics Data System (ADS)

The solid oxide fuel cell (SOFC) is an electrochemical device that converts chemical to electrical energy. It is usually based around an oxide conducting ceramic electrolyte that requires temperatures above 800°C to operate. There are many advantages to lowering this operation temperature such as more gas sealing options and more efficient startup. One of the key limitations is in the transport of ions across the electrolyte. The most common electrolyte material used is Yttria-Stabilized Zirconia (YSZ). The ionic conductivity can be greatly affected by grain boundaries, dislocations, and point defects. In this study, dislocations were introduced by heavy ion irradiation. Irradiation with Xe+ or Ar+ produced a large number of point defects and dislocations via a mechanism similar to Frank partial dislocation formation. The dislocation density was on the order of 1012/cm2 and the Burgers vector was 1/2<110>. Heat treatment at temperatures from 800-1400°C changed the defect structure, eliminated point defects, and allowed dislocations to react and grow. Thin films of YSZ were deposited on silicon substrates using pulsed laser deposition (PLD). Films deposited on a metallized substrate were polycrystalline while films deposited directly onto conductive silicon could be epitaxially grown. Ion irradiation caused the film conductivity to drop by a factor of 2-3 due to additional point defects in the film. Heat treatment removed these point defects allowing the conductivity to recover. A novel method was developed to produce freestanding YSZ membranes without a silicon substrate by using the Focused Ion Beam (FIB). Thick, single-crystal YSZ pieces were thinned using in-situ X-Ray Energy Dispersive Spectroscopy (EDS) for end point detection. The final membranes were single crystal, less than 350nm thick, and pinhole free. IV curves and impedance measurements were made after irradiation and heat treatment. The conductivity showed similar trends to the PLD deposited thin films. In addition to the ohmic losses from the electrolyte, ion implantation also affected the activation losses of the electrode. Single crystal electrolytes were implanted with various species. The exchange current density improved by an order of magnitude following irradiation with Na+ and Xe+ on the cathode side.

Cheng, Jeremy

39

Photoionization cross section calculations for the halogen-like ions Kr+ and Xe+  

NASA Astrophysics Data System (ADS)

Photoionization cross section calculations on the halogen-like ions; Kr+ and Xe+ have been performed for a photon energy range from each ion threshold to 15 eV, using large-scale close-coupling calculations within the Dirac-Coulomb R-matrix approximation. The results from our theoretical work are compared with recent measurements made at the ASTRID merged-beam set-up at the University of Aarhus in Denmark and from the Fourier transform ion cyclotron resonance trap method at the SOLEIL synchrotron radiation facility in Saint-Aubin, France Bizau et al (2011 J. Phys. B: At. Mol. Opt. Phys. 44 055205) and the advanced light source Müller (2012 private communication), Aguliar et al (2012 J. Phys.: Conf. Ser. at press). For each of these complex ions our theoretical cross section results over the photon energy range investigated are seen to be in excellent agreement with experiment. Resonance energy positions and quantum defects of the prominent Rydberg resonances series identified in the spectra are compared with experiment for these complex halogen-like ions.

McLaughlin, B. M.; Ballance, C. P.

2012-04-01

40

Heavy ion irradiation of thin gate oxides  

Microsoft Academic Search

We have studied the gate leakage current after heavy ion irradiation of MOS capacitors with thin gate oxides. In 3-nm and 4-nm oxides radiation-induced soft breakdown (RSB) occurs even after ion fluences as small as 100 ion hits on the device surface. The RSB conductive paths likely reproduce the ion hit distribution: some of them can drive a substantial fraction

M. Ceschia; A. Paccagnella; M. Turrini; A. Candelori; G. Ghidini; J. Wyss

2000-01-01

41

Multifragmentation in intermediate energy {sup 129}Xe-induced heavy-ion reactions  

SciTech Connect

The {sup 129}Xe-induced reactions on {sup nat}Cu, {sup 89}Y, {sup 165}Ho, and {sup 197}Au at bombarding energies of E/A = 40 & 60 MeV have been studied theoretically and experimentally in order to establish the underlying mechanism of multifragmentation at intermediate energy heavy-Ion collisions. Nuclear disks formed in central heavy-ion collisions, as simulated by means of Boltzmann-like kinetic equations, break up into several fragments due to a new kind of Rayleigh-like surface instability. A sheet of liquid, stable in the limit of non-interacting surfaces, is shown to become unstable due to surface-surface interactions. The onset of this instability is determined analytically. A thin bubble behaves like a sheet and is susceptible to the surface instability through the crispation mode. The Coulomb effects associated with the depletion of charges in the central cavity of nuclear bubbles are investigated. The onset of Coulomb instability is demonstrated for perturbations of the radial mode. Experimental intermediate-mass-fragment multiplicity distributions for the {sup 129}Xe-induced reactions are shown to be binomial at each transverse energy. From these distributions, independent of the specific target, an elementary binary decay probability p can be extracted that has a thermal dependence. Thus it is inferred that multifragmentation is reducible to a combination of nearly independent emission processes. If sequential decay is assumed, the increase of p with transverse energy implies a contraction of the emission time scale. The sensitivity of p to the lower Z threshold in the definition of intermediate-mass-fragments points to a physical Poisson simulations of the particle multiplicities show that the weak auto-correlation between the fragment multiplicity and the transverse energy does not distort a Poisson distribution into a binomial distribution. The effect of device efficiency on the experimental results has also been studied.

Tso, Kin

1996-05-01

42

Swift heavy ion irradiation reduces porous silicon thermal conductivity  

NASA Astrophysics Data System (ADS)

While the electrical conductivity of semiconductors can be easily changed over order of magnitudes (8 in silicon) by playing on the doping, the thermal conductivity (TC) control is a challenging issue. Nevertheless, numerous applications require TC control in Si down to 1 W m-1 K-1. Among them, there are thermal insulation requirements in MEMS, thermal management issues in 3D packaging or TC reduction for thermoelectric applications. Towards this end, the formation of nanoporous Si by electrochemical anodisation is efficient. Nevertheless, in this case the material is too fragile for MEMS application or even to withstand CMOS technological processes. In this work, we show that ion irradiation in the electronic regime is efficient for reducing TC in meso-porous Si (PSi), which is more mechanically robust than the nanoporous PSi. We have studied three different mass to energy ratios (238U at 110 MeV and 130Xe at 91 MeV and 29 MeV) with fluences ranging from 1012 cm-2 to 7 × 1013 cm-2. The sample properties, after irradiation, have been measured by infrared spectroscopy, Raman spectroscopy and scanning electron microscopy. The TC has been measured using scanning thermal microscopy. Although, bulk Si is insensitive to ion interaction in the electronic regime, we have observed the amorphisation of the PSi resulting in a TC reduction even for the low dose and energy. For the highest irradiation dose a very important reduction factor of four was obtained.

Massoud, M.; Canut, B.; Newby, P.; Frechette, L.; Chapuis, P. O.; Bluet, J. M.

2014-12-01

43

129I-derived and 244Pu-Fission Xe in Individual Neutron-Irradiated Phosphate Crystals from the Acapulco Meteorite  

NASA Astrophysics Data System (ADS)

In an effort to locate the primary carriers of radiogenic ^129Xe and to couple I-Xe chronometry to other dating techniques we have measured Xe in 17 individual phosphate grains from the meteorite Acapulco using a laser extraction technique. This is the first time I-Xe chronometry has been performed on a suite of individual grains. Excess radiogenic and fissiogenic Xe have previously been observed in the two parent calcium phosphate mineral separates (~66% Cl-apatite and 34% merrilite) from the Acapulco meteorite (c.f. Kim et al., 1992). In the present study, nine Cl-apatite grains and eight merrilite grains were n-irradiated with ~1.6x10^19 n/cm^2. I-derived Xe (^129Xe(sub)r from now-extinct ^129I and ^128Xe from the n-irradiation) and fission Xe (^244Pu and ^235U-neutron induced) are clearly measurable in single microgram-size phosphates (Figs. 1,2). Radiogenic Xe is enriched in the apatites relative to the halogen-free merrilite grains, as would be expected if I were incorporated into the grains in the same manner as Cl. No excess 129Xe(sub)rad is evident in any of the merrilite grains. Inferred initial I ratios indicate that the onset of radiogenic Xe retention in most of the apatite grains occurred ~4-5 Ma after Bjurbole. The average inferred initial (^244Pu/^238U)(sub)0 ratios (at the onset of fissiogenic Xe retention) are 0.006(1) for the apatites and 0.13(7) for the merrilites. The average ^129Xe(sub)rad concentration for the single apatites (1.0x10^-9 cc/g +- 20%) is slightly higher than that in the phosphate separates (0.4-0.5x10^-9 cc/g), and the average ^132Xe(sub)Pu concentrations for the apatites (0.6x10^-9 cc/g +- 20%) and merrilites (0.7xlO^-9 cc/g +- 20%) are both higher than those in the separates (~0.3x10^-9 cc/g). These differences may reflect variations in the apatite/merrilite content of the separates or variations in the purity of the single grains. That Pu was enriched in merrilite relative to Cl- apatite is consistent with previous analyses of ordinary chondrite phosphate grains (Crozaz et al., 1989). Different retention times for fission Xe and radiogenic Xe could reflect either a differential systematic Xe closure or, more likely, chemical fractionation, as evidenced by variations in initial (^244Pu/^238U)(sub)0 ratios following variations in REE patterns in the two minerals (c.f. Crozaz et al., 1989). Kim Y., Kim J.S. and Marti K. (1992) Lunar Planet. Sci. Conf: (abstract) 23, 691-692; Crozaz G., Pellas P., Bourot-Denise M., de Chazal S.M., Fieni C., Lundberg L. and Zinner E. (1989) Earth and Planet. Sci. Lett. 93, 157-159. Figure 1, which in the hard copy appears here, shows I-derived Xe Acapulco Cl-apatatites. Figure 2, which in the hard copy appears here, shows fission Xe Acapulco phosphates.

Nichols, R. H., Jr.; Hohenberg, C. M.; Marti, K.

1992-07-01

44

TEM, XRD and nanoindentation characterization of Xenon ion irradiation damage in austenitic stainless steels  

NASA Astrophysics Data System (ADS)

Cross-sectional and bulk specimens of a 20% cold-worked 316 austenitic stainless steel (CW 316 SS) has been characterized by TEM, XRD and nanoindentation to determine the microstructural evolution and mechanical property changes of 316 SS after irradiation with 7 MeV Xe26+ ions. TEM results reveal the presence of dislocation loops with a number density of approximately 3 × 1022 m-3 and sizes between 3 to 10 nm due to the collapse of vacancy rich cores inside displacement cascades. Peak broadening observed in XRD diffraction patters reveal systematic changes to lattice parameters due to irradiation. The calculated indentation values in irradiated 316 SS were found to be much higher in comparison to the unirradiated specimen, indicating the dose dependent effect of irradiation on hardness. The relationship between irradiation induced microstructural evolution and the changes to the mechanical properties of CW 316 SS are discussed in the context of fluence and irradiation temperature.

Huang, H. F.; Li, J. J.; Li, D. H.; Liu, R. D.; Lei, G. H.; Huang, Q.; Yan, L.

2014-11-01

45

Heavy Ion Irradiated Ferromagnetic Films: The Cases of Cobalt and Iron  

NASA Astrophysics Data System (ADS)

Polycrystalline, e-gun deposited Co, Fe and Co/Fe films, tens of nanometers thick, have been irradiated with Ne, Kr, Xe and/or Fe ions to fluences of up to 5 × 1016 ions/cm2. Changes in the magnetic texture induced by the implanted ions have been measured by means of hyperfine methods, such as Magnetic Orientation Mössbauer Spectroscopy (Fe), and by Magneto-Optical Kerr Effect and Vibrating Sample Magnetometry. In Co and CoFe an hcp ? fcc phase transition has been observed under the influence of Xe-ion implantation. For 1016 Xe-ions/cm2, ion beam mixing in the Co/Fe system produces a soft magnetic material with uniaxial anisotropy. The effects have been correlated with changes in the microstructure as determined via X-ray diffraction. The influences of internal and external strain fields, an external magnetic field and pre-magnetization have been studied. A comprehensive understanding of the various effects and underlying physical reasons for the modifications appears to emerge from these investigations.

Lieb, K. P.; Zhang, K.; Müller, G. A.; Gupta, R.; Schaaf, P.

2005-01-01

46

Creation of surface and bulk defects of germanium and surface roughening of germanium during high energy ion irradiation  

NASA Astrophysics Data System (ADS)

The formation of nanocavities depends strongly on temperature since the formation of nanocavities depends on kinetics of bulk point defects (vacancies and interstitials) produced by ion irradiation. More nanocavities are formed deeper inside the Ge crystal at 500°C compared to 400°C, while much smaller number of nanocavities are formed at 600°C. Due to the low mobility of bulk point defects at 400°C, not all the implanted Xe atoms are contained in the observed nanocavities, while probably almost all the implanted Xe atoms are contained in the nanocavities at 500°C. At 600°C, the areal density of implanted Xe atoms is small and no Xe peak is detected by RBS due to the high mobility of bulk point defects and Xe atoms. Large pits, which are more than several bilayers deep, are formed on Ge even when less than a bilayer of surface material is removed. The number of large pits initially increases and then decreases with increasing ion fluence, and even 650 eV Xe ions can create large pits on Ge. Large pits are formed on Ge due to the annihilation of nanocavities on the Ge surface by the interaction of displacement cascades of keV Xe ions with nanocavities. 20 keV Xe ions can create small pits on Ge(111), which are more than a bilayer deep, as well as large pits. The creation of small pits is due to surface damage creation process by single 20 keV Xe ions. Surface patterns of valleys and mounds are observed at 250°C and 275°C due to the asymmetric kinetics of surface vacancies at step edges, while no surface pattern formation is observed at room temperature. Also, model of Politi and Villain agrees relatively well with the roughening and coarsening of the Ge(111) surfaces etched by 5 keV Xe ions at 250°C and 275°C. At 300°C, a surface pattern is observed only when the incident ion direction is parallel to the step direction; this surface pattern is the ripple morphology produced by curvature dependent sputtering yield.

Kim, Jaichan

47

Swift heavy ion irradiation of ZnO nanoparticles embedded in silica: Radiation-induced deoxidation and shape elongation  

SciTech Connect

ZnO nanoparticles (NPs) embedded in amorphous SiO{sub 2} were irradiated with 200 MeV Xe{sup 14+} swift heavy ions (SHIs) to a fluence of 5.0 × 10{sup 13} ions/cm{sup 2}. Optical linear dichroism was induced in the samples by the irradiation, indicating shape transformation of the NPs from spheres to anisotropic ones. Transmission electron microscopy observations revealed that some NPs were elongated to prolate shapes; the elongated NPs consisted not of ZnO but of Zn metal. The SHI irradiation induced deoxidation of small ZnO NPs and successive shape elongation of the deoxidized metal NPs.

Amekura, H.; Tsuya, D.; Mitsuishi, K.; Nakayama, Y. [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0003 (Japan)] [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0003 (Japan); Okubo, N.; Ishikawa, N. [Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki (Japan)] [Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki (Japan); Singh, U. B.; Khan, S. A.; Avasthi, D. K. [Inter-University Accelerator Centre (IUAC), New Delhi (India)] [Inter-University Accelerator Centre (IUAC), New Delhi (India); Mohapatra, S. [Guru Gobind Singh Indraprastha University, New Delhi (India)] [Guru Gobind Singh Indraprastha University, New Delhi (India)

2013-11-11

48

Ion irradiation-induced diffusion in bixbyite-fluorite related oxides: Dislocations and phase transformation  

NASA Astrophysics Data System (ADS)

Ion-irradiation induced diffusion and the phase transformation of a bixbyite-fluorite related rare earth oxide thin films are studied. This work is focused on yttrium sesquioxide, Y2O3, thin films deposited on Si (1 0 0) substrates using the ion beam sputtering technique (IBS). As-deposited samples were annealed ant then irradiated at cryogenic temperature (80 K) with 260 keV Xe2+ at different fluences. The irradiated thin oxide films are characterized by X-ray diffraction. A cubic to monoclinic phase transformation was observed. Analysis of this phenomenon is done in terms of residual stresses. Stress measurements as a function of irradiation fluences were realised using the XRD-sin2? method. Stress evolution and kinetic of the phase transformation are compared and leads to the role-played by the nucleation of point and extended defects.

Rolly, Gaboriaud; Fabien, Paumier; Bertrand, Lacroix

2014-05-01

49

Fluence and ion dependence of amorphous iron-phase-formation due to swift heavy ion irradiation in electrodeposited iron thin films  

NASA Astrophysics Data System (ADS)

57Fe conversion electron Mössbauer spectroscopy, XRD and AFM measurements were used to study the radiation effect of 246 MeV Kr, 470 MeV Xe and 710 MeV Bi ions on electrochemically deposited iron thin films. It was found that, in the irradiated electrochemically deposited crystalline ferromagnetic ?-Fe coatings, partial amorphisation of Fe took place. The relative amount of the ferromagnetic amorphous phase increased with both ion energy and ion mass as well as with the fluence of irradiation.

Stichleutner, S.; Kuzmann, E.; Havancsák, K.; Huhn, A.; El-Sharif, M. R.; Chisholm, C. U.; Doyle, O.; Skuratov, V.; Homonnay, Z.; Vértes, A.

2011-03-01

50

Alkali ion exchange in ?-irradiated glasses  

NASA Astrophysics Data System (ADS)

The alkali ion exchange of ?-irradiated glasses was investigated using the structural energy barrier model for ion exchange of glasses. It is shown that rates of alkali ion exchange have a non-Arrhenius behaviour depending both on irradiation dose and dose rate. For this reason some effects cannot be simulated by external irradiation and require in situ measurements. Higher doses and dose rates of ?-radiation lead to increased ion exchange rates. Significant changes occur in the activation energies demonstrating a many times decrease depending on glass composition. Radiation-induced changes are higher at relatively low temperatures being diminished by increased glass temperature. Numerical estimations show that changes in alkali ion exchange kinetics occur below the glass network damaging doses.

Ojovan, Michael I.; Lee, William E.

2004-12-01

51

Relativistic many-body Moller-Plesset perturbation theory calculations of the energy levels and transition rates in Na-like to P-like Xe ions  

SciTech Connect

Relativistic multireference many-body perturbation theory calculations have been performed for Xe{sup 43+} to Xe{sup 39+} ions, resulting in energy levels, electric dipole transition rates, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, the frequency-dependent Breit correction, and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.

Vilkas, Marius J.; Ishikawa, Yasuyuki [Department of Chemistry, University of Puerto Rico, P.O. Box 23346, San Juan, PR 00931-3346 (Puerto Rico); Traebert, Elmar [Astronomisches Institut, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); High Temperature and Astrophysics Division, LLNL, P.O. Box 808, Livermore, CA 94550 (United States)], E-mail: traebert@astro.rub.de

2008-09-15

52

Damage accumulation in gallium nitride irradiated with various energetic heavy ions  

NASA Astrophysics Data System (ADS)

In this work a study of damage production in gallium nitride via elastic collision process (nuclear energy deposition) and inelastic collision process (electronic energy deposition) using various heavy ions is presented. Ordinary low-energy heavy ions (Fe + and Mo + ions of 110 keV), swift heavy ions ( 208Pb 27+ ions of 1.1 MeV/u) and slow highly-charged heavy ions (Xe n+ ions of 180 keV) were employed in the irradiation. Damage accumulation in the GaN crystal films as a function of ion fluence and temperature was studied with RBS-channeling technique, Raman scattering technique, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For ordinary low-energy heavy ion irradiation, the temperature dependence of damage production is moderate up to about 413 K resulting in amorphization of the damaged layer. Enhanced dynamic annealing of defects dominates at higher temperatures. Correlation of amorphization with material decomposition and nitrogen bubble formation was found. In the irradiation of swift heavy ions, rapid damage accumulation and efficient erosion of the irradiated layer occur at a rather low value of electronic energy deposition (about 1.3 keV/nm 3), which also varies with irradiation temperature. In the irradiation of slow highly-charged heavy ions (SHCI), enhanced amorphization and surface erosion due to potential energy deposition of SHCI was found. It is indicated that damage production in GaN is remarkably more sensitive to electronic energy loss via excitation and ionization than to nuclear energy loss via elastic collisions.

Zhang, C. H.; Song, Y.; Sun, Y. M.; Chen, H.; Yang, Y. T.; Zhou, L. H.; Jin, Y. F.

2007-03-01

53

Measurement of a magnetic-dipole transition probability in Xe{sup 32+} using an electron-beam ion trap  

SciTech Connect

The transition probability for the 3d{sup 45}D{sub 2}{l_arrow}{sup 5}D{sub 3} magnetic-dipole transition in Ti-like Xe (Xe{sup 32+}) has been measured using an electron-beam ion trap. The unusually weak dependence of the transition energy on nuclear charge Z, and the fact that the transition wavelength remains in the 320- to 400-nm range for 54{lt}Z{lt}92, makes this transition promising as a plasma diagnostic tool. Our measurement of the transition probability yields 465(30) s{sup {minus}1}, corresponding to a lifetime of 2.15(14) ms, in good agreement with the theoretical value of 2.4 ms. {copyright} {ital 1997} {ital The American Physical Society}

Serpa, F.G.; Morgan, C.A.; Meyer, E.S.; Gillaspy, J.D. [Atomic Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-0001 (United States)] [Atomic Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-0001 (United States); Traebert, E. [Experimentalphysik III, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)] [Experimentalphysik III, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Church, D.A. [Physics Department, Texas AM University, College Station, Texas 77843-4242 (United States)] [Physics Department, Texas AM University, College Station, Texas 77843-4242 (United States); Takacs, E. [Experimental Physics Department, Kossuth University, Bem ter 18/a, Debrecen H-4026 (Hungary)] [Experimental Physics Department, Kossuth University, Bem ter 18/a, Debrecen H-4026 (Hungary); [Institute for Nuclear Research of the Hungarian Academy of Sciencies (ATOMKI), Bem ter 18/c, Debrecen, H-4026 (Hungary)

1997-06-01

54

Heavy ion irradiation of crystalline water ice  

E-print Network

Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic ...

Dartois, E; Boduch, P; Brunetto, R; Chabot, M; Domaracka, A; Ding, J J; Kamalou, O; Lv, X Y; Rothard, H; da Silveira, E F; Thomas, J C

2015-01-01

55

Effects of swift heavy ion irradiation parameters on optical properties of muscovite mica  

NASA Astrophysics Data System (ADS)

Muscovite mica sheets with a thickness of 25 ?m were irradiated by various kinds of swift heavy ions (Sn, Xe and Bi) in HIRFL (Heavy Ion Research Facility in Lanzhou). The fluences ranged from 1 × 1010 to 8 × 1011 ions/cm2 were applied. The electronic energy loss (dE/dx)e in mica was changed from 14.7 to 31.2 keV/nm. The band gaps and Urbach energy of pristine and irradiated mica were analyzed by ultraviolet-visible spectroscopy (UV-Vis). A red shift of the absorption edge was found in the absorption spectra of muscovite mica irradiated by ions with increasing (dE/dx)e. The results show that the chemical bonds between Tetrahedral-Octahedral-Tetrahedral (TOT) layers of mica were destroyed by ion irradiation. With increasing (dE/dx)e and fluences, the band gaps became narrow and the Urbach energy increased. It suggests that the amount of defects and the proportion of amorphous structure were increased in mica irradiated with increasing (dE/dx)e and fluences.

Zhang, S. X.; Liu, J.; Zeng, J.; Song, Y.; Mo, D.; Yao, H. J.; Duan, J. L.; Sun, Y. M.; Hou, M. D.

2015-01-01

56

Swift heavy ion irradiation of InP: Thermal spike modeling of track formation  

NASA Astrophysics Data System (ADS)

Irradiation of single-crystalline InP with swift heavy ions (SHI’s) causes the formation of ion tracks for certain irradiation temperatures if the electronic energy deposition exceeds a threshold value. With increasing SHI fluence, more and more ion tracks are formed, until a continuous amorphous layer is produced due to the multiple overlapping of the tracks at high ion fluences. Single-crystalline InP samples were irradiated either at liquid nitrogen temperature (LNT) or at room temperature (RT) with Kr, Xe, or Au ions with specific energies ranging from ca. 0.3to3.0MeV/u . Afterwards, the samples were investigated by means of Rutherford backscattering spectrometry and transmission electron microscopy in the plan-view and cross-section geometry. We show that the experimental data obtained can be qualitatively and quantitatively described on the basis of the inelastic thermal spike (TS) model, which was originally used only for metallic targets. The presented extension of the TS model on semiconductors covers mainly the very first stage of the energy transfer from SHI’s (so-called “ionization spikes”). Our results show that the extended TS model offers a self-consistent way to explain the influence of various irradiation conditions (ion mass, ion energy, irradiation temperature, etc.) on the ion track formation and damage accumulation in InP and, therefore, can make a contribution to a better understanding of the underlying mechanisms. Further, our results prejudice the amenity of a single value of the threshold electronic energy loss as a fundamental quantity that is commonly used for the description of track formation in solids irradiated with different ion species. There is no universal RT threshold for track formation in InP, but it is noticeably higher for lighter ions (12.0 and 14.8keV/nm for RT irradiations with Au and Xe, respectively). Our experimental and simulation results support the idea that the formation of visible tracks requires a predamaging of the material, unless each SHI penetrating perfectly ordered virgin InP directly produces a track that is large enough to be stable.

Kamarou, A.; Wesch, W.; Wendler, E.; Undisz, A.; Rettenmayr, M.

2006-05-01

57

Ion beam irradiation in La2Zr2O7Ce2Zr2O7 pyrochlore  

Microsoft Academic Search

Generally, zirconate pyrochlores do not experience a radiation-induced transformation from the crystalline-to-amorphous state, but rather disorder to a defect fluorite structure-type. Thus Gd2Zr2O7 has been proposed as a nuclear waste form for the immobilization of plutonium because of its radiation ``stability''. In contrast, La2Zr2O7 can be amorphized by a 1.5 MeV Xe+ ion irradiation (~5.5 dpa at room temperature), and

J. Lian; L. M. Wang; R. G. Haire; K. B. Helean; R. C. Ewing

2004-01-01

58

Ion beam irradiation in La 2Zr 2O 7–Ce 2Zr 2O 7 pyrochlore  

Microsoft Academic Search

Generally, zirconate pyrochlores do not experience a radiation-induced transformation from the crystalline-to-amorphous state, but rather disorder to a defect fluorite structure-type. Thus Gd2Zr2O7 has been proposed as a nuclear waste form for the immobilization of plutonium because of its radiation “stability”. In contrast, La2Zr2O7 can be amorphized by a 1.5 MeV Xe+ ion irradiation (?5.5 dpa at room temperature), and

J. Lian; L. M. Wang; R. G. Haire; K. B. Helean; R. C. Ewing

2004-01-01

59

Effect of swift heavy ion irradiation on single- and multiwalled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The effect of irradiation with swift heavy ions on the structure and properties of carbon nanotubes was investigated by Raman spectroscopy. It was found that disordering of the system occurred mainly at the surface. No ordering phenomena have been observed over a whole range of both fluences and electronic stopping powers studied. The disorder parameter (i.e., the ratio of the D and G band intensities (ID/IG)) increases non-linearly with the irradiation dose, showing a tendency to saturate at high fluences. The increase in the disorder parameter upon irradiation was proportional to the square root of the ion fluence. The radiation stability of the few-walled nanotubes was ca. 1.6 higher than that of the single-walled ones. The irradiation with both the Xe and Kr ions leads to essentially the same increase in the ID/IG ratio with respect to the deposited electronic energy density. In the case of the Ar ion irradiation, the observed increase in the ID/IG ratio is much lower, suggesting that the electronic stopping power threshold for defects creation in carbon nanotubes is lower than that for graphite.

Olejniczak, Andrzej; Skuratov, Vladimir A.

2014-05-01

60

Ion irradiation effects in natural garnets: Comparison with zircon  

E-print Network

Ion irradiation effects in natural garnets: Comparison with zircon S. Utsunomiya, L.M. Wang, R ; Z ¼ 8) under ion-beam irradiation was investigated in order to compare its radiation susceptibility during the ion irradiation at high temperature. This behavior may be related to the phase relations

Utsunomiya, Satoshi

61

Amorphization of Al 2SiO 5 polymorphs under ion beam irradiation  

NASA Astrophysics Data System (ADS)

The three polymorphs of Al 2SiO 5 (kyanite, andalusite and sillimanite) were irradiated with 1.5 MeV Xe + using the HVEM-Tandem Facility at Argonne National Laboratory. Irradiations were completed over a temperature range of 300 to 973 K. In situ TEM, followed by HREM, was used to characterize the effects of the ion beam damage. All three Al 2SiO 5 polymorphs became amorphous after doses of 0.3 dpa at room temperature. However, the high temperature behavior of the three phases was different. The thermodynamic stabilities of the three phases were found not to have a direct relation to susceptibility to amorphization. Irradiation-induced amorphization is discussed in terms of a cascade quenching model.

Wang, S. X.; Wang, L. M.; Ewing, R. C.

1997-05-01

62

Evolution of helium bubbles in aluminum during heavy-ion irradiation  

NASA Astrophysics Data System (ADS)

The evolution of individual He bubbles in thin Al foils during 200-keV Xe irradiation at room-temperature has been followed with in situ transmission electron microscopy. He bubbles were produced by room-temperature implantation of 3-keV He ions into prethinned aluminum samples. During subsequent xenon irradiation, several distinct processes were observed to cause individual He bubbles to increase or decrease in size. Bubble growth was observed to take place by radiation-induced coalescence of bubbles without bubble motion. This coalescence was a result of the net displacement of Al atoms out of the volume between bubbles initially in close proximity. The resulting nonequilibrium-shaped bubble evolved towards a more energetically favorable spherical shape whose final size was determined by equilibrium bubble pressure. Bubbles were observed to disappear as the specimen surface was removed by sputtering. Bubbles unaffected by sputtering were observed to decrease in size at an average rate of 0.1 to 0.2 nm/(1015 Xe/cm2) or 0.024 to 0.048 nm/dpa (displacements per atom). This rate of bubble shrinkage can be understood on the basis of direct displacement of He out of the bubble while the bubble remains at equilibrium pressure. He resolution occurred at a rate of 0.005 to 0.01 (Heejected/He)/dpa. No examples were found that would indicate complete destruction of a bubble by a single Xe ion. Bubble centers remained fixed during bubble shrinkage indicating negligible bubble motion during room-temperature irradiation.

Birtcher, R. C.; Donnelly, S. E.; Templier, C.

1994-07-01

63

Chromosomal instability induced by heavy ion irradiation  

NASA Technical Reports Server (NTRS)

PURPOSE: To establish the dose-response relationship for the induction of chromosomal instability in GM10115 cells exposed to high-energy iron ions (1 GeV/nucleon, mean LET 146 keV/microm) and gold ions (11 GeV/nucleon, mean LET 1450 keV/microm). Past work has established that sparsely ionizing X-rays can induce a long-lived destabilization of chromosomes in a dose-dependent manner at an incidence of approximately 3% per gray. The present investigation assesses the capacity of High-Z and High-energy (HZE) particles to elicit this same endpoint. MATERIALS AND METHODS: Clonal populations derived from single progenitor cells surviving heavy-ion irradiation were analyzed cytogenetically to identify those clones showing a persistent destablization of chromosomes. RESULTS: Dose-response data, with a particular emphasis at low dose (< 1.0 Gy), indicate a frequency of approximately 4% per gray for the induction of chromosomal instability in clones derived from single progenitor cells surviving exposure to iron ions. The induction of chromosomal instability by gold ions was, however, less responsive to applied dose, as the observed incidence of this phenotype varied from 0 to 10% over 1-8 Gy. Both iron and gold ions gave dose-dependent increases in the yield of chromosomal aberrations (both chromosome- and chromatid-type) measured at the first mitosis following irradiation, as well as shoulderless survival curves having D0=0.87 and 1.1 Gy respectively. CONCLUSIONS: Based on the present dose-response data, the relative biological effectiveness of iron ions is 1.3 for the induction of chromosomal instability, and this indicates that heavy ions are only slightly more efficient than X-rays at eliciting this delayed phenotype.

Limoli, C. L.; Ponnaiya, B.; Corcoran, J. J.; Giedzinski, E.; Morgan, W. F.

2000-01-01

64

Microstructure of Swift Heavy Ion Irradiated MgAl(Sub 2)O(Sub 4) Spinel  

SciTech Connect

Plan view and cross-section transmission electron microscopy was used to investigate the microstructure of magnesium aluminate spinel (MgAl{sub 2}O{sub 4}) following room temperature irradiation with either 430 MeV Kr, 614 MeV Xe, or 72 MeV I ions. The fluences ranged from 1 x 10{sup 16}/m{sup 2} (single track regime) to 1 x 10{sup 20}/m{sup 2}. Destruction of the ordered spinel crystal structure on both the anion and cation sublattices was observed in the ion tracks at low fluences. At intermediate fluences, the overlapping ion tracks induced the formation of a new metastable crystalline phase. Amorphization with a volumetric expansion of {approximately}35% was observed in spinel irradiated with swift heavy ions (electronic stopping powers >7 keV/nm) at fluences above 1 x 10{sup 19}/m{sup 2}. These results demonstrate that swift heavy ion radiation can induce microstructural changes not achievable with conventional elastic collision irradiation at comparable temperatures.

Matzke, H.; Skuratov, V.A.; Zinkle, S.J.

1998-11-30

65

Raman spectroscopy of ion-irradiated astrophysically relevant materials  

Microsoft Academic Search

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

G. A. Baratta; R. Brunetto; G. Leto; M. E. Palumbo; F. Spinella; G. Strazzulla

2008-01-01

66

Ion irradiated graphite exposed to fusion-relevant deuterium plasma  

NASA Astrophysics Data System (ADS)

Graphite samples were irradiated with 5 MeV carbon ions to simulate the damage caused by collision cascades from neutron irradiation in a fusion environment. The ion irradiated graphite samples were then exposed to a deuterium plasma in the linear plasma device, MAGPIE, for a total ion fluence of ?1 × 1024 ions m-2. Raman and near edge X-ray absorption fine structure (NEXAFS) spectroscopy were used to characterize modifications to the graphitic structure. Ion irradiation was observed to decrease the graphitic content and induce disorder in the graphite. Subsequent plasma exposure decreased the graphitic content further. Structural and surface chemistry changes were observed to be greatest for the sample irradiated with the greatest fluence of MeV ions. D retention was measured using elastic recoil detection analysis and showed that ion irradiation increased the amount of retained deuterium in graphite by a factor of four.

Deslandes, Alec; Guenette, Mathew C.; Corr, Cormac S.; Karatchevtseva, Inna; Thomsen, Lars; Ionescu, Mihail; Lumpkin, Gregory R.; Riley, Daniel P.

2014-12-01

67

Local brain heavy ion irradiation induced Immunosuppression  

NASA Astrophysics Data System (ADS)

Purpose: To investigate the long term effect of acute local brain heavy ion irradiation on the peripheral immune system in rat model. Methodology: Only the brain of adult male Wistar rats were radiated by heavy ions at the dose of 15 Gy. One, two and three months after irradiation, thymus and spleen were analyzed by four ways. Tunel assay was performed to evaluate the percentage of apoptotic cells in thymus and spleen, level of Inflammatory cytokines (IL-2, IL-6, SSAO, and TNF-?) was detected by ELISA assay, the differentiation of thymus T lymphocyte subsets were measured by flow cytometry and the relative expression levels of genes related to thymus immune cell development were measured by using quantitative real-time PCR. Results: Thymus and spleen showed significant atrophy from one month to three months after irradiation. A high level of apoptosis in thymus and spleen were obtained and the latter was more vulnerable, also, high level of inflammatory cytokines were found. Genes (c-kit, Rag1, Rag2 and Sca1) related to thymus lymphocytes’ development were down-regulated. Conclusion: Local area radiation in the rat brain would cause the immunosuppression, especially, the losing of cell-mediated immune functions. In this model, radiation caused inflammation and then induced apoptosis of cells in the immune organs, which contributed to immunosuppression.

Lei, Runhong; Deng, Yulin; Huiyang Zhu, Bitlife.; Zhao, Tuo; Wang, Hailong; Yu, Yingqi; Ma, Hong; Wang, Xiao; Zhuang, Fengyuan; Qing, Hong

68

Unexpected transverse velocity component of Xe{sup +} ions near the exit plane of a Hall thruster  

SciTech Connect

The velocity component of singly charged xenon ions in a plane perpendicular to the thrust axis of the 1 kW-class PPS100-ML Hall effect thruster is deduced from laser induced fluorescence measurements on the 5d {sup 2}F{sub 7/2}{yields}6p {sup 2}D{sub 5/2}{sup 0} electronic transition at 834.72 nm. Measurements are carried out at several locations in the near field of the channel exhaust. Thruster operating parameters, such as magnetic field strength, discharge voltage, and xenon mass flow rate, are varied over a wide range. The initial aim of this work was to measure the azimuthal velocity of the ions due to their weak magnetic deflection. Surprisingly, experimental results cannot be explained by the one and only Lorentz force acting on Xe{sup +} ions. A realistic picture of the ion trajectory in the ExB drift plane is obtained when adding a velocity component directed toward the external cathode.

Bourgeois, G.; Mazouffre, S. [ICARE, CNRS, 1C Avenue de la Recherche Scientifique, 45071 Orleans (France); Sadeghi, N. [LSP, Joseph Fourier University and CNRS, 140 Ave. de la Physique, 38402 St. Martin d'Heres (France)

2010-11-15

69

EFFECT OF ION BEAM IRRADIATION ON HARDNESS OF POLYETHYLENE TEREPHTHALATE  

Microsoft Academic Search

Ion beam irradiation as one of the effective methods of polymer modification has been used on the PET films. The ion beam used was Li(50 MeV) of various fluences. The Vickers' hardness of the films irradiated at different ion fluences was measured. The hardness tests on each film were carried out at different loads. The true bulk hardness of the film

N. L. Singh; C. F. Desai; N. Shah; P. H. Soni; V. Shrinet; D. K. Avasthi

2002-01-01

70

Temperature and ion-mass dependence of amorphization dose for ion beam irradiated zircon (ZrSiO{sub 4})  

SciTech Connect

The temperature dependence of amorphization dose for zircon under 1.5 MeV Kr ion irradiation has been investigated using the ANL HVEM-Tandem Facility. Three regimes were observed in the amorphization dose-temperature curve. In the first regime (15 to 300 K), the critical amorphization dose increased from 3.06 to 4.5 ions/nm{sup 2}. In the second regime (300 to 473 K), there is little change in the amorphizationdose. In the third regime (> 473 K), the amorphization dose increased exponentially to 8.3 ions/nm{sup 2} at 913 K. This temperature dependence of amorphization dose can be described by two processes with different activation energies (0.018 and 0.31 eV respectively) which are attributed to close pair recombination in the cascades at low temperatures and radiation-enhanced epitaxial recrystallization at higher temperatures. The upper temperature limit for amorphization of zircon is estimated to be 1100 K. The ion-mass dependence of the amorphization dose (in dpa) has also been discussed in terms of the energy to recoils based on data obtained from He, Ne, Ar, Kr, Xe irradiations and a {sup 238}Pu-doped sample.

Wang, L.M.; Ewing, R.C. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Geology; Weber, W.J. [Pacific Northwest Lab., Richland, WA (United States); Eby, R.K. [Toronto Univ., ON (Canada). Dept. of Geological Sciences

1992-12-01

71

Temperature and ion-mass dependence of amorphization dose for ion beam irradiated zircon (ZrSiO[sub 4])  

SciTech Connect

The temperature dependence of amorphization dose for zircon under 1.5 MeV Kr ion irradiation has been investigated using the ANL HVEM-Tandem Facility. Three regimes were observed in the amorphization dose-temperature curve. In the first regime (15 to 300 K), the critical amorphization dose increased from 3.06 to 4.5 ions/nm[sup 2]. In the second regime (300 to 473 K), there is little change in the amorphizationdose. In the third regime (> 473 K), the amorphization dose increased exponentially to 8.3 ions/nm[sup 2] at 913 K. This temperature dependence of amorphization dose can be described by two processes with different activation energies (0.018 and 0.31 eV respectively) which are attributed to close pair recombination in the cascades at low temperatures and radiation-enhanced epitaxial recrystallization at higher temperatures. The upper temperature limit for amorphization of zircon is estimated to be 1100 K. The ion-mass dependence of the amorphization dose (in dpa) has also been discussed in terms of the energy to recoils based on data obtained from He, Ne, Ar, Kr, Xe irradiations and a [sup 238]Pu-doped sample.

Wang, L.M.; Ewing, R.C. (New Mexico Univ., Albuquerque, NM (United States). Dept. of Geology); Weber, W.J. (Pacific Northwest Lab., Richland, WA (United States)); Eby, R.K. (Toronto Univ., ON (Canada). Dept. of Geological Sciences)

1992-12-01

72

I-Xe systematics in LL chondrites  

NASA Technical Reports Server (NTRS)

A stepwise heating analysis of Ar and Xe data from five neutron-irradiated whole rock LL chondrites (Soko Banja, Alta Ameen, Tuxtuac, Guidder, and Olivenza) is presented, emphasizing the complicated thermal history of ordinary chondrites. None of the present meteorites show a well-defined (Ar-40)-(Ar-39) apparent age plateau comprised of more than two release fractions. Most of the samples are found to yield well-defined high-temperature correlations between Xe-129/Xe-130 and Xe-128/Xe-130, and thus determinations of I-129/I-127 and Xe-129/Xe-130 at the time of isotopic closure for Xe. As in the case of other ordinary chondrites, the I-Xe systematics for LL chondrites correlate neither with a metamorphic grade nor with chronologies based opon other methods.

Bernatowicz, T. J.; Podosek, F. A.; Swindle, T. D.; Honda, M.

1988-01-01

73

Stress evolution in platinum thin films during low-energy ion irradiation  

SciTech Connect

Stress evolution of Pt thin films during low-energy ion irradiation is investigated by using wafer bending measurements and molecular dynamics simulations. Noble gas ions ranging in mass from He to Xe and energy from 0.5 to 5 keV are used. Depending on the type and energy of the ion, the change in stress can either be tensile or compressive. Heavier or higher-energy ions tend to create tensile stress, while lighter ions such as He always induce compressive stress. The stress evolution also depends on the initial state of stress in the thin films. The results are explained by a competition between the tensile stress induced by local melting along the ion track and the compressive stress induced by the accumulation of ion-induced interstitials in defect clusters or grain boundaries, often beyond the calculated ion penetration depth. Anisotropic diffusion of interstitials under an external stress field also plays an important role in the stress evolution. Molecular dynamics simulation is employed to evaluate the importance of each of these microscopic mechanisms.

Chan Wailun; Zhao Kai; Vo, Nhon; Cahill, David G.; Averback, Robert S. [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Ashkenazy, Yinon [Racah Institute of Physics, Hebrew University of Jerusalem, 91904 Jerusalem (Israel)

2008-05-15

74

Neurite outgrowth on fluorinated polyimide film micropatterned by ion irradiation  

NASA Astrophysics Data System (ADS)

In this study, we investigated neurite outgrowth on a fluorinated polyimide film micropatterned by ion irradiation. We used the fluorinated polyimide because of its excellent thermal and mechanical properties and biocompatibility. Rattus norvegicus chromaphin (PC12) cells were used for in vitro studies. The polyimide films were irradiated with He +, Ne + or Kr + at 1 × 10 14 ions/cm 2 using an ion-beam mask. The lines in the mask were 120 and 160 ?m wide and 120-160 ?m apart. PC12 cells were selectively adhered on the polyimide film micropatterned by Kr +-irradiation. However, the neurite length on the film irradiated by Kr + was shorter than that determined in the film irradiated by He +. On the other hand, neurite outgrowth on the polyimide film micropatterned by He +-irradiation was at least 100 ?m in length. This initial study indicated the enhanced outgrowth of PC12 cells on the fluorinated polyimide film micropatterned by ion irradiation.

Okuyama, Y.; Sato, M.; Nagaoka, S.; Kawakami, H.; Suzuki, Y.; Iwaki, M.

2003-05-01

75

Surface Modification of Polymer Substrates by Oxygen Ion Irradiation  

SciTech Connect

Oxygen cluster ions and/or monomer ions were used for the sputtering and the surface modification of polymers such as polycarbonate (PC) and polyethylene terephthalate (PET). For the case of oxygen cluster ion irradiation, the sputtered depth increased with increase of the acceleration voltage, and the sputtering yield was much larger than that by the monomer ion irradiation. The sputtered particles represented the polymer structure, which indicated that the bond scission by the cluster ion irradiation resulted in an ejection of monomer molecule through the intermolecular collision. On the other hand, for the oxygen monomer ion irradiation, the implanted depth increased with increase of the acceleration voltage, and the bond scission occurred at the deep region through the binary collision with the high energetic ions. Therefore, the sputtering yield for the polymer surfaces decreased, and the sputtering effect became very small. Furthermore, the simultaneous use of oxygen cluster and monomer ions was more effective for oxidation of the PET surfaces rather than the monomer ion irradiation or the cluster ion irradiation. As a result, the contact angle measurement showed that the wettability of the PET surfaces irradiated by the simultaneous use of oxygen cluster and monomer ions was much enhanced.

Takaoka, G. H.; Ryuto, H.; Araki, R.; Yakushiji, T. [Photonics and Electronics Science and Engineering Center, Kyoto University, Nishikyo, Kyoto 615-8510 (Japan)

2008-11-03

76

Raman Scattering in Natural Diamond Crystals Implanted with High-Energy Ions and Irradiated with Fast Neutrons  

NASA Astrophysics Data System (ADS)

Raman scattering is studied in natural diamond crystals with radiation-induced defects produced by implantation of high energy Xe and Kr ions (ion kinetic energy >1 MeV/amu) and by irradiation with fast reactor neutrons (kinetic energy >100 keV). Confocal measurements of the Raman spectra along the surface of an oblique section of the ionimplanted diamonds are used to study the radiation damage profile. The evolution of the Raman scattering spectra with depth of the damaged layer in the ion-implanted diamonds, and as a function of annealing temperature of the neutron-irradiated diamond, is determined by spatial localization of phonons in the radiation disordered crystal lattice and by the formation of associations of intrinsic defects in the lattice.

Poklonskaya, O. N.; Vyrko, S. A.; Khomich, A. A.; Averin, A. A.; Khomich, A. V.; Khmelnitsky, R. A.; Poklonskia, N. A.

2015-01-01

77

Focused-ion-beam cross-sectioning techniques using XeF2  

Microsoft Academic Search

We have developed an ion-assisted gas etching (IAGE) technique which enhances existing focused ion beam (FIB) failure analysis (FA) cross-sectioning techniques. Preliminary results show enhanced sputter removal rate of certain materials, decoration of material interfaces or boundaries, and preferential etching of materials particularly difficult to image with standard secondary imaging systems. In particular we show two examples of IAGE using

Diane K. Stewart; Michael J. Vasile

1992-01-01

78

Amorphous molecular junctions produced by ion irradiation on carbon nanotubes  

NASA Astrophysics Data System (ADS)

Experiments and molecular dynamics have demonstrated that electron irradiation could create molecular junctions between crossed single-wall carbon nanotubes. Recently molecular dynamics computation predicted that ion irradiation could also join single-walled carbon nanotubes. Employing carbon ion irradiation on multi-walled carbon nanotubes, we find that these nanotubes evolve into amorphous carbon nanowires, more importantly, during the process of which various molecular junctions of amorphous nanowires are formed by welding from crossed carbon nanotubes. It demonstrates that ion-beam irradiation could be an effective way not only for the welding of nanotubes but also for the formation of nanowire junctions.

Wang, Zhenxia; Yu, Liping; Zhang, Wei; Ding, Yinfeng; Li, Yulan; Han, Jiaguang; Zhu, Zhiyuan; Xu, Hongjie; He, Guowei; Chen, Yi; Hu, Gang

2004-04-01

79

Energy dependence of nanopillars formation on InSb semiconductor surfaces under gallium FIB and noble gas ions beam irradiation  

NASA Astrophysics Data System (ADS)

We have studied the formation and evolution of ion beam-induced pillars growth on InSb(0 0 1) surface through a comparison of irradiation with Ga (Focused Ion Beam) and noble gas ion (Ar, Kr, Xe) beams. Room temperature, normal incidence ion irradiation was carried out with the ion beam energy of 1-3 keV for noble gas and 3-30 keV for FIB Ga ions. The surface morphology of the developed structures and their chemical composition were investigated by means of scanning and transmission electron microscopy (SEM/TEM). We have examined the evolution from the initial flat InSb surface, through clusters formation, at initial stages of irradiation (ion beam fluence of 5 × 1016 ions/cm2), to the pillar structure formation at higher ion fluences (2.8 × 1017 ions/cm2), for both kinds of projectiles. The projectile ion energy dependence of the pillar size, height and density was studied for both kinds of ion species for the first time. It has been found that the pillar sizes and heights exhibit the power-law dependence on projectile energy with the same exponent for both kinds of the ion species. The TEM measurements uncovered crystalline InSb core of the pillar and In/Ga enriched amorphous tip and shell structure. We confirmed a universal mechanism of pillars formation based on redeposition of the sputtered sample material for both ion species i.e. noble gas ions and Ga FIB.

Jany, B. R.; Szajna, K.; Nikiel, M.; Wrana, D.; Trynkiewicz, E.; Pedrys, R.; Krok, F.

2015-02-01

80

In-pile Xe diffusion coefficient in UO 2 determined from the modeling of intragranular bubble growth and destruction under irradiation  

NASA Astrophysics Data System (ADS)

Intragranular bubbles grow in the nuclear fuel by diffusion and precipitation of fission gases, mainly xenon; and are ultimately destroyed, under irradiation, by fission fragments. This article will attempt to determine the in-pile bubble distributions taking into account the evolution of the concentration profile around a bubble during its growth and the destruction process by fission fragments. From these distributions a relation between the bubble mean radius and the diffusion coefficient of xenon can be established, allowing the determination, from experimental measurements of intragranular bubble sizes, of the in-pile Xe diffusion coefficient in UO 2. The estimated activation energy (0.9 eV) is about one order of magnitude lower than the widely used value of 3.9 eV determined from out-of-pile experiments. This effect can be attributed to the presence of point defects created by the irradiation.

Govers, K.; Lemehov, S.; Verwerft, M.

2008-03-01

81

80 A/cm2 electron beams from metal targets irradiated by KrCl and XeCl excimer lasers  

NASA Astrophysics Data System (ADS)

Due to the growing demand for high-current and long-duration electron-beam devices, laser electron sources were investigated in our laboratory. Experiments on electron-beam generation and propagation from aluminium and copper targets illuminated by XeCl (308 nm) and KrCl (222 nm) excimer lasers, were carried out under plasma ignition due to laser irradiation. This plasma supplied a spontaneous accelerating electric field of about 370 kV/m without an external accelerating voltage. By applying the modified one-dimensional Poisson equation, we computed the expected current and we also estimated the plasma concentration during the accelerating process. At 40 kV of accelerating voltage, an output current pulse of about 80 A/cm2 was detected from an Al target irradiated by the shorter wavelength laser.

Beloglazov, A.; Martino, M.; Nassisi, V.

1996-05-01

82

Concurrent in situ ion irradiation transmission electron microscope  

NASA Astrophysics Data System (ADS)

An in situ ion irradiation transmission electron microscope has been developed and is operational at Sandia National Laboratories. This facility permits high spatial resolution, real time observation of electron transparent samples under ion irradiation, implantation, mechanical loading, corrosive environments, and combinations thereof. This includes the simultaneous implantation of low-energy gas ions (0.8-30 keV) during high-energy heavy ion irradiation (0.8-48 MeV). Initial results in polycrystalline gold foils are provided to demonstrate the range of capabilities.

Hattar, K.; Bufford, D. C.; Buller, D. L.

2014-11-01

83

Emulation of reactor irradiation damage using ion beams  

SciTech Connect

The continued operation of existing light water nuclear reactors and the development of advanced nuclear reactor depend heavily on understanding how damage by radiation to levels degrades materials that serve as the structural components in reactor cores. The first high dose ion irradiation experiments on a ferritic-martensitic steel showing that ion irradiation closely emulates the full radiation damage microstructure created in-reactor are described. Ferritic-martensitic alloy HT9 (heat 84425) in the form of a hexagonal fuel bundle duct (ACO-3) accumulated 155 dpa at an average temperature of 443°C in the Fast Flux Test Facility (FFTF). Using invariance theory as a guide, irradiation of the same heat was conducted using self-ions (Fe++) at 5 MeV at a temperature of 460°C and to a dose of 188 displacements per atom. The void swelling was nearly identical between the two irradiations and the size and density of precipitates and loops following ion irradiation are within a factor of two of those for neutron irradiation. The level of agreement across all of the principal microstructure changes between ion and reactor irradiations establishes the capability of tailoring ion irradiations to emulate the reactor-irradiated microstructure.

G. S. Was; Z. Jiao; E. Beckett; A. M. Monterrosa; O. Anderoglu; B. H. Sencer; M. Hackett

2014-10-01

84

The NIST compilation of ionization potentials revisited: From He-like to Xe-like ions  

E-print Network

The National Institute of Standards and Technology (NIST) database on ionization potentials for neutral atoms and ions is examined. For each isoelectronic sequence, we construct a regularized perturbative series that exactly matches the large-$Z$ and $Z\\approx N-1$ regions. Comparison of the NIST data with this series allows the identification of problematic data values.

Gil, Gabriel

2014-01-01

85

Target K-vacancy production by 2.5 to 25 MeV/amu Ar, Kr, and Xe ions  

SciTech Connect

Cross sections have been measured for K{alpha} x-ray production in targets of Al, Ti, Cu, Zr, Ag, Sm, and Ta by Ar, Kr, and Xe ions ranging in energy from 2.5 to 25 MeV/amu. In addition, the degree of simultaneous L-shell ionization and the enhancement of the K{alpha} diagram lines due to secondary ionization processes were assessed by performing high-resolution spectral measurements on Al, Ti, V, Co, and Cu targets. This information was used to correct for the K{alpha} x-ray yield produced by electron bombardment and photoionization, and to calculate the fluorescence yields needed to convert the K{alpha} x-ray production cross sections into K-vacancy production cross sections. The resulting cross sections were compared with the predictions of the perturbed stationary state approximation with corrections for projectile energy loss, Coulomb deflection, and relativistic effects (ECPSSR theory). Also, the scaling properties of the K{alpha} x-ray production cross sections were examined and a semiempirical (universal) curve was deduced that reproduces the measured cross sections to within {+-}30% on average.

Watson, R. L.; Peng, Y.; Horvat, V.; Perumal, A. N. [Cyclotron Institute and Department of Chemistry, Texas A and M University, College Station, Texas 77843-3366 (United States)

2006-12-15

86

Target K -vacancy production by 2.5to25MeV/amu Ar, Kr, and Xe ions  

NASA Astrophysics Data System (ADS)

Cross sections have been measured for K? x-ray production in targets of Al, Ti, Cu, Zr, Ag, Sm, and Ta by Ar, Kr, and Xe ions ranging in energy from 2.5to25MeV/amu . In addition, the degree of simultaneous L -shell ionization and the enhancement of the K? diagram lines due to secondary ionization processes were assessed by performing high-resolution spectral measurements on Al, Ti, V, Co, and Cu targets. This information was used to correct for the K? x-ray yield produced by electron bombardment and photoionization, and to calculate the fluorescence yields needed to convert the K? x-ray production cross sections into K -vacancy production cross sections. The resulting cross sections were compared with the predictions of the perturbed stationary state approximation with corrections for projectile energy loss, Coulomb deflection, and relativistic effects (ECPSSR theory). Also, the scaling properties of the K? x-ray production cross sections were examined and a semiempirical (universal) curve was deduced that reproduces the measured cross sections to within ±30% on average.

Watson, R. L.; Peng, Y.; Horvat, V.; Perumal, A. N.

2006-12-01

87

Shrinkage effects of polyimide film under ion beam irradiation  

Microsoft Academic Search

Ion beam induced electrical conduction of ion implanted polyimide film could find potential applications for encapsulation of microelectronic devices and gate-transistor fabrication. One of the important problems to be solved is the shrinkage effect of polyimide film under ion beam irradiation. In this work the shrinkage effects of B+-implanted polyimide film under different implantation conditions were investigated by using different

X. L. Xu; Yu Yuehui; Lin Zixin; Chen Lizhi; Fang Fang; Zhou Zuyao; Zou Shichang; Du Gendi; Xia Guanqun

1991-01-01

88

Amorphization of ceramic materials by ion-beam-irradiation: Parallels to glass formation  

SciTech Connect

Ion-beam-induced amorphization of a wide variety of ceramic materials has been investigated using in situ TEM at the HVEM-Tandem Facility at Argonne National Laboratory with 1.5 MeV Kr{sup +} or Xe{sup +} ions at temperatures between 20 to 1,000 K. The critical amorphization temperatures and the activation energies associated with the epitaxial recovery of displacement cascades during irradiation have been determined from the temperature dependence of the critical amorphization dose. The results for phases in the Al{sub 2}O{sub 3}-MgO-SiO{sub 2} system suggested a parallel in the kinetics between ion-beam-induced amorphization and glass formation. Based on a cascade quenching model, a semiempirical parameter, S, which can easily be calculated from both structural and chemical parameters of a material, has been developed to predict the susceptibility of ceramics to amorphization. The critical amorphization temperature, above which irradiation-induced amorphization cannot be completed, is closely related to the glass transition temperature. The ratio between glass transition and melting temperatures can also be used to predict the susceptibility of a ceramic material to amorphization, equivalent to the Debye temperature criterion.

Wang, L.M.; Wang, S.X.; Gong, W.L.; Ewing, R.C. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Earth and Planetary Sciences

1997-11-01

89

The interactions of high-energy, highly charged Xe ions with buckyballs  

SciTech Connect

Ionization and fragmentation have been measured for C{sub 60} molecules bombarded by highly charged (up to 35+) xenon ions with energies ranging up to 625 MeV. The observed mass distribution of positively charged fragments is explained in terms of a theoretical model indicating that the total interaction cross section contains roughly equal contributions from (a) excitation of the giant plasmon resonance, and (b) large-energy-transfer processes that lead to multiple fragmentation of the molecule. Preliminary results of measurements on VUV photons emitted in these interactions are also presented.

Ali, R.; Berry, H.G.; Cheng, S. [and others

1994-12-31

90

Damaged carbon nanotubes get healed by ion irradiation  

SciTech Connect

Carbon nanotubes (CNTs) are being used for varied applications. It is therefore important to study their stability under extreme conditions of temperature and irradiation. In this work, we report the stability of CNTs [both single-wall CNTs (SWCNTs) and multiwalled CNTs (MWCNTs)] under irradiation of a carbon ion beam of energy 55 MeV. The irradiated samples were analyzed using Raman spectroscopy. The Raman results indicate the interesting phenomenon of healing or annealing of CNTs under ion beam irradiation. The annealing process appears to begin at the lowest value of fluences and persists for quite a good range of fluence values. As the irradiation dose increases ({approx_equal}1x10{sup 14} ions/cm{sup 2}) the MWCNTs begin to amorphize whereas the SWCNTs system continues to heal.

Jeet, Kiran; Jindal, V. K.; Dharamvir, Keya [Department of Physics, Panjab University, Chandigarh 160014 (India); Bharadwaj, L. M. [Biomolecular Electronic and Nanotechnology Division, Central Scientific Instruments Organisation, Sector 30-C, Chandigarh 160030 (India); Avasthi, D. K. [Materials Science Group, Inter University Accelerator Centre, Aruna Asaf Ali Marg, P.O. Box 10502, New Delhi 110067 (India)

2010-08-15

91

Enhanced electrochemical etching of ion irradiated silicon by localized amorphization  

SciTech Connect

A tailored distribution of ion induced defects in p-type silicon allows subsequent electrochemical anodization to be modified in various ways. Here we describe how a low level of lattice amorphization induced by ion irradiation influences anodization. First, it superposes a chemical etching effect, which is observable at high fluences as a reduced height of a micromachined component. Second, at lower fluences, it greatly enhances electrochemical anodization by allowing a hole diffusion current to flow to the exposed surface. We present an anodization model, which explains all observed effects produced by light ions such as helium and heavy ions such as cesium over a wide range of fluences and irradiation geometries.

Dang, Z. Y.; Breese, M. B. H. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore Singapore 117542 (Singapore); Lin, Y.; Tok, E. S. [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Vittone, E. [Physics Department, NIS Excellence Centre and CNISM, University of Torino, via Pietro Giuria 1, 10125 Torino (Italy)

2014-05-12

92

Amino Acids from Ion-Irradiated Nitrile-Containing Ices  

Microsoft Academic Search

Solid CH3CN and solid H2OCH3CN were ion irradiated near 10 K to initiate chemical reactions thought to occur in extraterrestrial ices. The infrared spectra of these samples after irradiation revealed the synthesis of new molecules. After the irradiated ices were warmed to remove volatiles, the resulting residual material was extracted and analyzed. Both unhydrolyzed and acid-hydrolyzed residues were examined by

Reggie L. Hudson; Marla H. Moore; Jason P. Dworkin; Mildred P. Martin; Zachary D. Pozun

2008-01-01

93

Ferromagnetism induced by heavy-ion irradiation in fullerene films  

NASA Astrophysics Data System (ADS)

Magnetic measurements using a superconducting quantum interference device and magnetic force microscopy were performed on fullerene films irradiated with 250keV Ar and 92MeV Si ions, to compare the effects of electronic excitation and collisional cascade on the magnetization. A ferromagnetic behavior increasing with ion fluence is observed. The magnetization is attributed to (i) the formation of an amorphous carbon network and (ii) the incorporation of oxygen in the irradiated films.

Kumar, Amit; Avasthi, D. K.; Pivin, J. C.; Tripathi, A.; Singh, F.

2006-10-01

94

Kuiper objects: simulation of space weathering by ion irradiation  

Microsoft Academic Search

Waiting for direct investigation of Kuiper Belt Objects surfaces, laboratory experiments are essential to understand mechanisms of space weathering. We present results of laboratory experiments on methane irradiation performed at Catania Observatory. Frozen methane at 16 K was irradiated by hundreds of keV Ar++ ions. Reflectance spectra from 0.65 \\\\micron to 2.7 \\\\micron have been taken ``in situ\\

J. Paillet; R. Brunetto; M. A. Barucci; E. Dotto; G. Strazulla

2003-01-01

95

Heavy-ion irradiation induced diamond formation in carbonaceous materials.  

SciTech Connect

The basic mechanisms of metastable phase formation produced under highly non-equilibrium thermodynamic conditions within high-energy particle tracks are investigated. In particular, the possible formation of diamond by heavy-ion irradiation of graphite at ambient temperature is examined. This work was motivated, in part, by earlier studies which discovered nanometer-grain polycrystalline diamond aggregates of submicron-size in uranium-rich carbonaceous mineral assemblages of Precambrian age. It was proposed that the radioactive decay of uranium formed diamond in the fission particle tracks produced in the carbonaceous minerals. To test the hypothesis that nanodiamonds can form by ion irradiation, fine-grain polycrystalline graphite sheets were irradiated with 400 MeV Kr ions. The ion irradiated graphite (and unirradiated graphite control) were then subjected to acid dissolution treatments to remove the graphite and isolate any diamonds that were produced. The acid residues were then characterized by analytical and high-resolution transmission electron microscopy. The acid residues of the ion-irradiated graphite were found to contain ppm concentrations of nanodiamonds, suggesting that ion irradiation of bulk graphite at ambient temperature can produce diamond.

Daulton, T. L.

1999-01-08

96

The response of the pyrochlore structure-type to ion-beam irradiation  

NASA Astrophysics Data System (ADS)

Pyrochlore with the general formula of A3+2B4+2O7 (Fd3m; Z = 8) has been proposed as the candidate waste form for the immobilization of actinides, particularly plutonium from dismantled nuclear weapons. Because actinides decay by alpha-decay events, radiation effects on the waste form are a concern. The effects of radiation on different pyrochlore compositions, A2B2O7 (A = La ˜ Lu, and Y; B = Ti, Sn, and Zr), have been investigated by 50 KeV He+, 600 KeV Ar+, 1.0 MeV Kr+, and 1.5 MeV Xe+ ion irradiations. Titanate pyrochlores are generally sensitive to ion beam damage and can be amorphized at a low damage level (˜0.2 dpa). The critical amorphization temperature, Tc, increases from ˜480 to ˜1120 K with increasing A-site cation size. A dramatically increasing radiation "resistance" to ion beam induced-amorphization has been observed with increasing Zr-content in the Gd2Ti2-xZrxO7 system. The pure end-member, Gd2Zr2O7, cannot be amorphized, even at doses as high as ˜100 dpa. Although zirconate pyrochlores are generally considered to be radiation "resistant", ion beam-induced amorphization occurs for La2Zr2O7 at a dose of ˜5.5 dpa at room temperature. Stannate pyrochlores A2Sn 2O7 (A = La, Nd, Gd) are readily amorphized by ion beam damage at a relatively low dose (˜1 dpa) at room temperature; while no evidence of amorphization has been observed in A2Sn2O7 (A = Er, Y, Lu) irradiated with 1 MeV Kr+ ions at a dose of ˜6 dpa at 25 K. The factors that influence the response of different pyrochlore compositions to ion irradiation-induced amorphization are discussed in terms of cation radius ratio, defect formation energies, and the tendency of the pyrochlore structure-type to undergo an order-disorder transition to the defect-fluorite structure. The "resistance" of the pyrochlore structure to ion beam-induced amorphization is not only affected by the relative sizes of the A- and B-site cations, but also the cation electronic configurations. Pyrochlore compositions that have larger structural deviations from the ideal fluorite structure are more sensitive to ion beam-induced amorphization. These fundamental results provide insight into the structural and compositional controls on radiation-induced amorphization of pyrochlores. This understanding can be used for the design and selection of materials used for the immobilization of actinides.

Lian, Jie

97

Charge transfer reactions in Xe plasma expansion  

NASA Astrophysics Data System (ADS)

Charge transfer reactions of fast Xe ions with hydrocarbons including methane (CH4), ethene (C2H4), and propane (C3H8) are studied by adding these hydrocarbon gases into a cross flowing Xe plasma expansion. Branching ratios and relative reaction rates for the charge transfers of fast Xe+ with each of the three hydrocarbon gases are measured under different rf powers of the inductively coupled Xe discharge. For CH4/Xe system, we find that fast Xe+ reacts readily with CH4 generating CH4+ and CH3+ in a ratio of 1:0.56, with an estimated rate coefficient of (2.3±0.3)×10-10cm3/s at 75W rf power which slowly increases to (2.9±0.3)×10-10cm3/s at 250W (error bars reflect only the uncertainties due to the unknown extent of the ion recombination that follows the charge transfer reaction). These observed charge transfer reactions are made possible by the kinetically excited Xe ions produced by free expansion of the plasma. For the C2H4/Xe system product ions C2H4+ and C2H2+ are observed, and for C3H8/Xe, C2H4+ and C2H5+ and minor product ions including C2H2+ and C3H7+ are observed.

Jiao, C. Q.; Garscadden, A.; Ganguly, B. N.

2007-04-01

98

GaP\\/Si heteroepitaxy by complex ion beam sputtering  

Microsoft Academic Search

We have investigated the sputter deposition using a complex ion beam formed with the mixture of Xe and PH3 to grow GaP epitaxial films on Si substrates. The complex ion beam was formed by the cold cathode ion source into which Xe and PH3 gases were fed via variable-leak valves. To reduce the ion beam irradiation damage in the deposited

F. Ishizuka; H. Yoshizawa; T. Itoh

1988-01-01

99

Formation, Dynamics, and Characterization of Nanostructures by Ion Beam Irradiation  

Microsoft Academic Search

Ion beam irradiation is a potential tool for phase formation and material modification as a non-equilibrium technique. Localized rise in temperature and ultra fast (?10 s) dissipations of impinging energy make it an attractive tool for metastable phase formation. As a matter of fact, a major component of materials science is dominated by ion beam methods, either for synthesis of

S. Dhara

2007-01-01

100

Deuterium retention of ferritic steel irradiated by energetic hydrogen ions  

NASA Astrophysics Data System (ADS)

Ferritic steel (F82H) was irradiated by energetic hydrogen ions to make a irradiation damage. The damaged ferritic steel was irradiated by deuterium ions with energy of 1.7 keV in order to investigate the retention and desorption behavior of deuterium. The deuterium ion fluence was taken up to 5 × 10 18 D/cm 2. The amount of retained deuterium increased as the deuterium ion fluence and saturated at 1 × 10 18 D/cm 2. It was clearly seen that the amount of retained deuterium increased as the damage caused by the hydrogen ion irradiation. For example, the amount of retained deuterium in the sample with 4 dpa was several times larger than that in the sample without damage. It was also seen that the desorption temperature approximately 70 K increased compared with that without damage. These results suggest that the number of trapping site and trapping energy for fuel hydrogen increases owing to the irradiation damage. The present results show that both fuel hydrogen recycling and in-vessel tritium inventory increases by the irradiation damage.

Hino, T.; Katada, Y.; Yamauchi, Y.; Akiba, M.; Suzuki, S.; Ezato, T.

2009-04-01

101

A laser spectroscopic study on Xe{sup +} ion transport phenomena in the ExB discharge of a Hall effect thruster  

SciTech Connect

The Velocity Distribution Function (VDF) of metastable Xe{sup +} ions was measured along the channel axis of the 5 kW-class PPS registered X000 Hall effect thruster by means of Laser Induced Fluorescence spectroscopy at 834.72 nm for various voltages, magnetic fields and mass flow rates. Axial velocity and dispersion profiles are compared to on-axis profiles obtained with the 1.5 kW-class PPS100 thruster. Outcomes of the comparison are threefold. (i) The broadening of the FDV across the region of strong magnetic field is a general feature for Hall thrusters. It originates in the overlap between ionization and acceleration layers. The velocity dispersion increases with the discharge voltage; it reaches up to 200 eV in unit of kinetic energy at 700 V. (ii) Most of the acceleration potential ({approx_equal}70%) is localized outside the thruster channel whatever the thruster size and operating conditions. The electric field moves upstream when the applied voltage is ramped up; in other words the fraction of potential inside the channel increases with the voltage; (iii) A non negligible amount of very slow and very fast (kinetic energy higher than the applied potential) Xe{sup +} ions are always observed. Such ions may find their origin in space and temporal oscillations of the electric field as suggested by numerical simulations carried out with a hybrid model.

Mazouffre, S.; Gawron, D.; Kulaev, V. [ICARE, CNRS, 1c Avenue de la Recherche Scientifique, 45071 Orleans (France); Luna, J. Perez [LAPLACE, 118 Route de Narbonne, 31062 Toulouse (France); Sadeghi, N. [LSP, Joseph-Fourier University-CNRS, 140 Avenue de la Physique, BP87, 38402 St Martin d'Heres (France)

2008-03-19

102

University of Wisconsin Ion Beam Laboratory: A facility for irradiated materials and ion beam analysis  

SciTech Connect

The University of Wisconsin Ion Beam Laboratory (UW-IBL) has recently undergone significant infrastructure upgrades to facilitate graduate level research in irradiated materials phenomena and ion beam analysis. A National Electrostatics Corp. (NEC) Torodial Volume Ion Source (TORVIS), the keystone upgrade for the facility, can produce currents of hydrogen ions and helium ions up to {approx}200 {mu}A and {approx}5 {mu}A, respectively. Recent upgrades also include RBS analysis packages, end station developments for irradiation of relevant material systems, and the development of an in-house touch screen based graphical user interface for ion beam monitoring. Key research facilitated by these upgrades includes irradiation of nuclear fuels, studies of interfacial phenomena under irradiation, and clustering dynamics of irradiated oxide dispersion strengthened steels. The UW-IBL has also partnered with the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) to provide access to the irradiation facilities housed at the UW-IBL as well as access to post irradiation facilities housed at the UW Characterization Laboratory for Irradiated Materials (CLIM) and other ATR-NSUF partner facilities. Partnering allows for rapid turnaround from proposed research to finalized results through the ATR-NSUF rapid turnaround proposal system. An overview of the UW-IBL including CLIM and relevant research is summarized.

Field, K. G.; Wetteland, C. J.; Cao, G.; Maier, B. R.; Gerczak, T. J.; Kriewaldt, K.; Sridharan, K.; Allen, T. R. [University of Wisconsin, Madison, WI 53706 (United States); Dickerson, C. [Argonne National Laboratory, Argonne, IL 60439 (United States); Field, C. R. [Naval Research Laboratory, Washington, DC 20375 (United States)

2013-04-19

103

University of Wisconsin Ion Beam Laboratory: A facility for irradiated materials and ion beam analysis  

NASA Astrophysics Data System (ADS)

The University of Wisconsin Ion Beam Laboratory (UW-IBL) has recently undergone significant infrastructure upgrades to facilitate graduate level research in irradiated materials phenomena and ion beam analysis. A National Electrostatics Corp. (NEC) Torodial Volume Ion Source (TORVIS), the keystone upgrade for the facility, can produce currents of hydrogen ions and helium ions up to ˜200 ?A and ˜5 ?A, respectively. Recent upgrades also include RBS analysis packages, end station developments for irradiation of relevant material systems, and the development of an in-house touch screen based graphical user interface for ion beam monitoring. Key research facilitated by these upgrades includes irradiation of nuclear fuels, studies of interfacial phenomena under irradiation, and clustering dynamics of irradiated oxide dispersion strengthened steels. The UW-IBL has also partnered with the Advanced Test Reactor National Scientific User Facility (ATR-NSUF) to provide access to the irradiation facilities housed at the UW-IBL as well as access to post irradiation facilities housed at the UW Characterization Laboratory for Irradiated Materials (CLIM) and other ATR-NSUF partner facilities. Partnering allows for rapid turnaround from proposed research to finalized results through the ATR-NSUF rapid turnaround proposal system. An overview of the UW-IBL including CLIM and relevant research is summarized.

Field, K. G.; Wetteland, C. J.; Cao, G.; Maier, B. R.; Dickerson, C.; Gerczak, T. J.; Field, C. R.; Kriewaldt, K.; Sridharan, K.; Allen, T. R.

2013-04-01

104

Pulsed ion irradiated microstructures in molybdenum  

NASA Astrophysics Data System (ADS)

Pulsed irradiation of molybdenum in the temperature range from 1025-1225 K primarily retarded void nucleation. The reduction in nucleation rate could be attributed to a throttling effect caused by annealing out of subcritical void embryos. The more rapid development of the dislocation microstructure during pulsing also contributed to a reduction in void nucleation rate. Once nucleation was complete, microstructural development was not affected by pulsed irradiation compared to steady irradiation. Little pulsing effect on total void swelling or swelling rate was observed. A proposed increase in swelling caused by disintegration of depleted zones during pulsed annealing periods was not observed.

Brimhall, J. L.; Simonen, E. P.; Charlot, L. A.

1984-05-01

105

On the relative importance of physical and chemical sputtering during ion-enhanced etching of silicon by XeF2  

NASA Astrophysics Data System (ADS)

Product translational energy distributions have been used in previous studies as a diagnostic of surface reaction enhancement mechanisms under ion bombardment. Haring and co-workers [R. A. Haring, A. Haring, F. W. Saris, and A. E. de Vries, Appl. Phys. Lett. 41, 174 (1982)] have taken an E-2 dependence for SiFx species desorbing during ion-enhanced etching of silicon as evidence for the importance of physical sputtering. In this work, the translational energy distribution of SiF4 desorbing from the surface of silicon during spontaneous etching by XeF2 has been obtained from modulated beam measurements. The distribution deviates markedly from a thermal distribution at the surface temperature and exhibits an E-2 dependence at high energy. Observation of this energy dependence both with and without ions suggests that translational energy distributions may not provide a unique signature for chemical and physical sputtering.

Houle, F. A.

1987-06-01

106

Development of dual-beam system using an electrostatic accelerator for in-situ observation of swift heavy ion irradiation effects on materials  

NASA Astrophysics Data System (ADS)

We have developed the dual beam system which accelerates two kinds of ion beams simultaneously especially for real-time ion beam analysis. We have also developed the alternating beam system which can efficiently change beam species in a short time in order to realize efficient ion beam analysis in a limited beam time. The acceleration of the dual beam is performed by the 20 UR Pelletron™ tandem accelerator in which an ECR ion source is mounted at the high voltage terminal [1,2]. The multi-charged ions of two or more elements can be simultaneously generated from the ECR ion source, so dual-beam irradiation is achieved by accelerating ions with the same charge to mass ratio (for example, 132Xe11+ and 12C+). It enables us to make a real-time beam analysis such as Rutherford Back Scattering (RBS) method, while a target is irradiated with swift heavy ions. For the quick change of the accelerating ion beam, the program of automatic setting of the optical parameter of the accelerator has been developed. The switchover time for changing the ion beam is about 5 min. These developments have been applied to the study on the ion beam mixing caused by high-density electronic excitation induced by swift heavy ions.

Matsuda, M.; Asozu, T.; Sataka, M.; Iwase, A.

2013-11-01

107

Controlling surface states and photoluminescence of porous silicon by low-energy-ion irradiation  

NASA Astrophysics Data System (ADS)

Porous silicon (PS) was irradiated by three kinds of low-energy ions with different chemical activity, namely argon ions, nitrogen ions and oxygen ions. The chemical activity of ions has significant effect on the surface states and photoluminescence (PL) properties of PS, The photoluminescence quenching after argon ions and nitrogen ions irradiation is ascribed to the broken Si-Si bonds, while the PL recovery is attributed to the oxidation of Si-H back bonds. Oxygen ions irradiation leads to the formation of a SiO x layer with oxygen defects and PS shows different PL evolution than PS irradiated by argon ions and nitrogen ions.

Du, X. W.; Jin, Y.; Zhao, N. Q.; Fu, Y. S.; Kulinich, S. A.

2008-02-01

108

Swift heavy ion irradiation of muscovite and biotite substrates  

NASA Astrophysics Data System (ADS)

We report magnetic and spectroscopic studies of naturally occurring layered phyllosilicates; muscovite and biotite of Sikkim Himalaya. The minerals are characterised by SEM-EDS, powder X-ray diffraction (pXRD), electron paramagnetic resonance (EPR) and magnetometry. EPR spectra of muscovite and its axial dependence show the presence of Mn2+ ions in the silicate sheets. The samples are irradiated with 120 MeV Au ions and the consequent structural modifications are analysed. The irradiation does not influence the compositions, structural and magnetic properties of these micas. Therefore, both muscovite and biotite are more suitable for use as substrates than many other materials routinely used as substrates for swift heavy ion irradiation measurements.

Tiwari, Archana; Tripathi, Ajay; Pathak, Anand P.

2015-01-01

109

Ion irradiation damage on tin side surface of float glass  

Microsoft Academic Search

Changes in the surface morphology and in-depth density variation in two surfaces of a float glass viz. the tin side and non-tin side surface, are investigated after 100keV Ar ion irradiation. In the tin side surface, the irradiation caused a drastic change in density and surface roughness, whereas the other side (non-tin side surface) remained almost unaffected. Roughness of the

Mohammed H. Modi; Gyanendra S. Lodha; Manoj K. Tiwari; Sanjay K. Rai; C. Mukharjee; P. Magudapathy; K. G. M. Nair; Rajendra V. Nandedkar

2005-01-01

110

Influence of 12C6+ ion irradiation on mutant avermitilis  

NASA Astrophysics Data System (ADS)

The effects of 12C+6 ion irradiation on colony morphology and mycelia morphology, as well as on mutation rate have been studied in the B1a high-product strains (ZJAV-Y1-203) mutated by heavy ion irradiation and compared with that in the original strain (ZJAV-A-1). After irradiating the rate of a straw hat colony type having a high ability of producing B1a in ZJAV-Y1-203 strains was higher than that found in ZJAV-A-1 strains. When strains were cultured in a liquid medium for 24 hours, the mycelium becoming thinner could be observed in all of the irradiated ZJAV- Y1-203 groups, but only in the ZJAV-A-1 groups irradiated at the dose of 50 Gy or more. The early growth of mycelium was inhibited in the ZJAV- Y1-203 group irradiated with a high dose. The highest positive mutation rate (23.5%) of ZJAV - Y1 - 203 was reached at the lower dose of 30 Gy while the highest positive mutation rate of 34.2% in ZJAV-A-1 appeared at 50 Gy. These results indicate that the effects of heavy ion irradiation still exist even in the mutated Streptomyces avermitilis, and only the dose is lower and the effects not so strong compared with the one that is first irradiated with optimized heavy ion doses. This is evidence of the one directional mutation being controlled by many more factors in a organism.

Wang, Shu-Yang; Chen, Ji-Hong; Li, Wen-Jian; Liang, Jian-Ping; Bo, Yong-Heng; Ma, Xiao-Qi; Liu, Jing

2012-11-01

111

Effect of aging on surface chemical bonds of PTFE irradiated by low energy Ti ion  

Microsoft Academic Search

Polytetrafluoroethylene (PTFE) was irradiated by low energy titanium ion in a metal vapor vacuum arc (MEVVA) implanter. The samples were irradiated with 80keV Ti ion with fluences from 5×1015 to 5×1017 Ti\\/cm2, respectively. Transportation of Ion in Matters (TRIM) code was employed to simulate Ti ion irradiation. The as-irradiated samples were investigated by ESCA, SEM and wettability. As increasing ion

Jizhong Zhang; Xiaoji Zhang; Hongyu Zhou

2003-01-01

112

Oxide glass structure evolution under swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

The effects of ion tracks on the structure of oxide glasses were examined by irradiating a silica glass and two borosilicate glass specimens containing 3 and 6 oxides with krypton ions (74 MeV) and xenon ions (92 MeV). Structural changes in the glass were observed by Raman and nuclear magnetic resonance spectroscopy using a multinuclear approach (11B, 23Na, 27Al and 29Si). The structure of irradiated silica glass resembles a structure quenched at very high temperature. Both borosilicate glass specimens exhibited depolymerization of the borosilicate network, a lower boron coordination number, and a change in the role of a fraction of the sodium atoms after irradiation, suggesting that the final borosilicate glass structures were quenched from a high temperature state. In addition, a sharp increase in the concentration of three membered silica rings and the presence of large amounts of penta- and hexacoordinate aluminum in the irradiated 6-oxide glass suggest that the irradiated glass is different from a liquid quenched at equilibrium, but it is rather obtained from a nonequilibrium liquid that is partially relaxed by very rapid quenching within the ion tracks.

Mendoza, C.; Peuget, S.; Charpentier, T.; Moskura, M.; Caraballo, R.; Bouty, O.; Mir, A. H.; Monnet, I.; Grygiel, C.; Jegou, C.

2014-04-01

113

Structural evolution of zirconium carbide under ion irradiation  

NASA Astrophysics Data System (ADS)

Zirconium carbide is one of the candidate materials to be used for some fuel components of the high temperature nuclear reactors planned in the frame of the Gen-IV project. Few data exist regarding its behaviour under irradiation. We have irradiated ZrC samples at room temperature with slow heavy ions (4 MeV Au, fluence from 10 11 to 5 × 10 15 cm -2) in order to simulate neutron irradiations. Grazing incidence X-Ray diffraction (GIXRD) and transmission electron microscopy (TEM) analysis have been performed in order to study the microstructural evolution of the material versus ion fluence. A high sensitivity to oxidation is observed with the formation of zirconia precipitates during the ion irradiations. Three damage stages are observed. At low fluence (<10 12 cm -2), low modifications are observed. At intermediate fluence, high micro-strains appear together with small faulted dislocation loops. At the highest fluence (>10 14 cm -2), the micro-strains saturate and the loops coalesce to form a dense dislocation network. No other structural modification is observed. The material shows a moderate cell parameter increase, corresponding to a 0.6 vol.% swelling, which saturates around 10 14 ions/cm 2, i.e., a few Zr dpa. As a result, in spite of a strong covalent bonding component, ZrC seems to have a behaviour under irradiation close to cubic metals.

Gosset, D.; Dollé, M.; Simeone, D.; Baldinozzi, G.; Thomé, L.

2008-02-01

114

Raman spectrum study of graphite irradiated by swift heavy ions  

NASA Astrophysics Data System (ADS)

Highly oriented pyrolytic graphites are irradiated with 40.5-MeV and 67.7-MeV 112Sn-ions in a wide range of fluences: 1 × 1011 ions/cm2?1 × 1014 ions/cm2. Raman spectra in the region between 1200 cm?1 and 3500 cm?1 show that the disorder induced by Sn-ions increases with ion fluence increasing. However, for the same fluence, the amount of disorder is greater for 40.5-MeV Sn-ions than that observed for 67.7-MeV Sn-ions, even though the latter has a slightly higher value for electronic energy loss. This is explained by the ion velocity effect. Importantly, ~ 3-cm?1 frequency shift toward lower wavenumber for the D band and ~ 6-cm?1 shift toward lower wavenumber for the 2D band are observed at a fluence of 1 × 1014 ions/cm2, which is consistent with the scenario of radiation-induced strain. The strain formation is interpreted in the context of inelastic thermal spike model, and the change of the 2D band shape at high ion fluence is explained by the accumulation of stacking faults of the graphene layers activated by radiation-induced strain around ion tracks. Moreover, the hexagonal structure around the ion tracks is observed by scanning tunneling microscopy, which confirms that the strains near the ion tracks locally cause electronic decoupling of neighboring graphene layers.

Zhai, Peng-Fei; Liu, Jie; Zeng, Jian; Yao, Hui-Jun; Duan, Jing-Lai; Hou, Ming-Dong; Sun, You-Mei; Ewing, Rodney Charles

2014-12-01

115

On the uptake of water vapor by ion irradiated polyimide  

NASA Astrophysics Data System (ADS)

It is known that ion-irradiated polymers are capable to adsorb dopants from solid, liquid or gaseous phases. For simple ambient atmosphere exposures, oxygen and water vapor are the most prominent dopants. Though the quantity of the latter one is not sufficient to be probed by conventional spectroscopic techniques, it can be detected indirectly via its ionic conductivity on applying a strong electric field along the track direction, as long as it is not yet masked by the intrinsic ion track conductivity, which is the case for low-fluence polymer irradiation. The conductivity is of similar order for most low-fluence irradiated polymers examined - namely 10-15-10-13 ?-1 cm-1. Water vapor uptake - as determined via the ion track conductivity - sensitively depends on the ambient air humidity, so that fresh low fluence irradiated polymers can act as humidity sensors. Aging however leads to rapid deterioration of this property within a week exposure time at ambient room temperature and pressure. The water vapor absorption process in tracks is reversible, and the amount of water retained depends specifically on the polymer. Thus, whereas for polyimide, polycarbonate, polypropylene, and polytetrafluoride some water vapor adsorption is detected, polymethylmethacrylate and polyethyleneterepthalate exhibit little or no effect. Moreover, uptake of water vapor is restricted to the latent ion tracks themselves, and is barely detectable in neighboring pristine material. It scales linearly with the deposition of electronic energy along the ion track.

Fink, D.; Klett, R.; Müller, M.; Hu, Xuanwen; Chadderton, L. T.; Wang, L.; Hillenbrand, J.

116

Heavy-ion irradiations of Fe and Fe-Cr model alloys, part 1: damage evolution in thin-foils at lower doses.  

SciTech Connect

The evolution of radiation damage in Fe and Fe-Cr alloys under heavy-ion irradiation was investigated using transmission electron microscopy. Thin foils were irradiated with 100 or 150 keV Fe{sup +} and Xe{sup +} ions at room temperature (RT) and 300 C. Dynamic observations followed the evolution of damage and the early stages in damage development are reported. Small (2-5 nm) dislocation loops first appeared at doses between 10{sup 16} and 10{sup 17} ions m{sup -2} in all materials. Loop number densities depended strongly on the foil orientation in pure Fe but not in Fe-Cr alloys. Number densities did not depend strongly on Cr content. For a given material, defect yields were higher for Xe{sup +} ions than for Fe{sup +} ions, and were higher at RT than at 300 C. Loops with both 100 and 1/2 111 Burgers vectors were identified. The proportion of 100 loops was larger, especially in pure Fe. Dynamic observations showed that: the contrast of some new loops developed over intervals as long as 0.2 s; hopping of 1/2 111 loops was induced by the ion and electron beams and was pronounced in ultra-pure iron; and many loops were lost during and after ion irradiation by glide to the foil surface. The number of loops retained was strongly dependent on the foil orientation in Fe, but less so in Fe-Cr alloys. This is due to lower loop mobility in Fe-Cr alloys, probably due to pinning by Cr atoms. Reduced loop loss probably explains the higher loop number densities in Fe-Cr alloys compared with pure Fe.

Yao, Z.; Hernandez-Mayoral, M.; Jenkins, M. L.; Kirk, M. A.; Univ. Oxford; CIEMAT Avendia Complutense

2008-07-31

117

Magnetization and susceptibility of ion irradiated granular magnetite films  

SciTech Connect

Superparamagnetic granular magnetite (Fe3O4) films with an average grain size of 3 nm have been found to be magnetized following 5.5 MeV Si2+ ion irradiation to a fluence of 1.0E16 ions/cm2 near room temperature. The film underwent a phase transition to ferromagnetism after the irradiation. X-ray diffraction study shows that the average grain size increased to 23 nm. There is a dramatic change in the microstructure, featuring particle aggregation and material condensation. Magnetic domains in the irradiated film are observed in the size range of tens to several hundreds of nanometers. The change in the magnetic properties is attributed to irradiation induced grain growth and structural modifications that lead to occurrence of magnetic anisotropy. There are dipolar interactions between the nanoparticles in both the unirradiated and irradiated films. Data fits for the in-phase alternating current magnetic susceptibility of the unirradiated film indicate that the blocking temperature is ~150 K, depending on frequency. A gradual Verwey transition for the irradiated film occurs at ~75 K, above which the susceptibility exhibits unusual behavior: a linear decrease with decreasing temperature. There are irreversible processes of magnetic domains during cooling and warming up between 10 and 300 K.

Jiang, Weilin; McCloy, John S.; Lea, Alan S.; Sundararajan, J. A.; Yao, Qi; Qiang, Y.

2011-04-26

118

Organics produced by ion irradiation of ices: Some recent results  

Microsoft Academic Search

Some results, recently obtained from laboratory experiments of ion irradiation of ice mixtures containing H, C, N, and O, are here summarized. They are relevant to the formation and evolution of complex organics on interstellar dust, comets and other small bodies in the external Solar System. In particular the formation of CN-bearing species is discussed. Interstellar dust incorporated into primitive

G. Strazzulla; M. E. Palumbo

2001-01-01

119

Effects of Ga ion-beam irradiation on monolayer graphene  

SciTech Connect

The effects of Ga ion on the single layer graphene (SLG) have been studied by Raman spectroscopy (RS), SEM, and field-effect characterization. Under vacuum conditions, Ga ion-irradiation can induce disorders and cause red shift of 2D band of RS, rather than lattice damage in high quality SLG. The compressive strain induced by Ga ion decreases the crystalline size in SLG, which is responsible for the variation of Raman scattering and electrical properties. Nonlinear out-put characteristic and resistance increased are also found in the I-V measurement. The results have important implications during CVD graphene characterization and related device fabrication.

Wang, Quan; Mao, Wei; Zhang, Yanmin; Shao, Ying; Ren, Naifei [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China)] [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Ge, Daohan [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China) [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2013-08-12

120

Symmetry energy extracted from fragments in relativistic energy heavy-ion collisions induced by 124,136Xe  

NASA Astrophysics Data System (ADS)

In the framework of a modified Fisher model, the ratio of the symmetry-energy coefficient to temperature ( a sym / T) is extracted from the fragment produced in the 124, 136Xe induced reactions using the isobaric yield ratio methods based on different approximations. It is found that for nuclei with the same neutron excess ( I ? N - Z) increases when the mass of the fragment increases, while for isobar a sym / T decreases when I increases. It is also found that the extracted a sym / T of the nucleus has very little dependence on the n/p ratio of the projectile, target, and the incident energies in the reaction.

Ma, Chun-Wang; Pu, Jie; Wei, Hui-Ling; Wang, Shan-Shan; Song, Heng-Li; Zhang, Sha; Chen, Li

2012-06-01

121

Ion Irradiation Effects in Synthetic Garnets Incorporating Actinides Satoshi Utsunomiya1  

E-print Network

Ion Irradiation Effects in Synthetic Garnets Incorporating Actinides Satoshi Utsunomiya1 , Lu the long term radiation effects due to radioactive decay can be simulated in short term with heavy ion-irradiation[3], many irradiation experiments using heavy ions have been completed in the potential ceramics

Utsunomiya, Satoshi

122

Ion emission from fused silica under 157-nm irradiation  

NASA Astrophysics Data System (ADS)

We present a summary of initial work on the etching of silica at 157 nm. At fluences well below the threshold for plasma formation, we have characterized the direct desorption of atomic ions from fused silica surfaces during 157-nm irradiation. The ion identities and kinetic energies were determined by time-resolved mass spectroscopy. The principal ions are Si+ and O+. The emission intensities are dramatically increased by treatments that are expected to increase the density of surfaces defects. Molecular dynamics simulations of the silica surface suggest that silicon ions bound at surface oxygen vacancies (analogous to E' centers) provide suitable configurations for emission. We propose that emission is best understood in terms of a hybrid mechanism involving both antibonding chemical forces (Menzel-Gomer-Redhead model) and repulsive electrostatic forces on the adsorbed ion after laser excitation of the underlying defect.

John, Sharon R.; Leraas, J. A.; Langford, S. C.; Dickinson, J. T.

2007-04-01

123

In-situ high temperature irradiation setup for temperature dependent structural studies of materials under swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

An in-situ high temperature (1000 K) setup is designed and installed in the materials science beam line of superconducting linear accelerator at the Inter-University Accelerator Centre (IUAC) for temperature dependent ion irradiation studies on the materials exposed with swift heavy ion (SHI) irradiation. The Gd2Ti2O7 pyrochlore is irradiated using 120 MeV Au ion at 1000 K using the high temperature irradiation facility and characterized by ex-situ X-ray diffraction (XRD). Another set of Gd2Ti2O7 samples are irradiated with the same ion beam parameter at 300 K and simultaneously characterized using in-situ XRD available in same beam line. The XRD studies along with the Raman spectroscopic investigations reveal that the structural modification induced by the ion irradiation is strongly dependent on the temperature of the sample. The Gd2Ti2O7 is readily amorphized at an ion fluence 6 × 1012 ions/cm2 on irradiation at 300 K, whereas it is transformed to a radiation-resistant anion-deficient fluorite structure on high temperature irradiation, that amorphized at ion fluence higher than 1 × 1013 ions/cm2. The temperature dependent ion irradiation studies showed that the ion fluence required to cause amorphization at 1000 K irradiation is significantly higher than that required at room temperature irradiation. In addition to testing the efficiency of the in-situ high temperature irradiation facility, the present study establishes that the radiation stability of the pyrochlore is enhanced at higher temperatures.

Kulriya, P. K.; Kumari, Renu; Kumar, Rajesh; Grover, V.; Shukla, R.; Tyagi, A. K.; Avasthi, D. K.

2015-01-01

124

Ion beam irradiated optical channel waveguides  

NASA Astrophysics Data System (ADS)

Nowadays, in the modern optical communications systems, channel waveguides represent the core of many active and passive integrated devices, such as amplifiers, lasers, couplers and splitters. Different materials and fabrication processes were investigated in order to achieve the aforementioned optoelectronic circuits with low costs and high performance and reproducibility. Nevertheless, the 2D guiding structures fabrication continues to be a challenging task in some of optical materials due to their susceptibility to mechanical and/or chemical damages which can occur during the different steps of the fabrication process. Here we report on channel waveguides demonstration in erbium doped Tungsten - Tellurite (Er3+:TeO2-WO3) glasses and BGO crystals by means of a masked ion beam and/or direct writing processes performed at different energy MeV and ions species. The evidence of the waveguides formation was investigated by microscopy techniques and micro Raman spectroscopy.

Bányász, I.; Rajta, I.; Nagy, G. U. L.; Zolnai, Z.; Havranek, V.; Pelli, S.; Veres, M.; Himics, L.; Berneschi, S.; Nunzi-Conti, G.; Righini, G. C.

2014-03-01

125

Comparison of Deuterium Retention for Ion-irradiated and Neutron-irradiated Tungsten  

SciTech Connect

The behavior of D retention for Fe{sup 2+}-irradiated tungsten with a damage of 0.025-3 dpa was compared with that for neutron-irradiated tungsten with 0.025 dpa. The D{sub 2} thermal desorption spectroscopy (TDS) spectra for Fe{sup 2+}-irradiated tungsten consisted of two desorption stages at 450 and 550 K, while that for neutron-irradiated tungsten was composed of three stages and an addition desorption stage was found at 750 K. The desorption rate of the major desorption stage at 550K increased as the displacement damage increased due to Fe{sup 2+} irradiation increasing. In addition, the first desorption stage at 450K was found only for damaged samples. Therefore, the second stage would be based on intrinsic defects or vacancy produced by Fe{sup 2+} irradiation, and the first stage should be the accumulation of D in mono-vacancy and the activation energy would be relatively reduced, where the dislocation loop and vacancy is produced. The third one was found only for neutron irradiation, showing the D trapping by a void or vacancy cluster, and the diffusion effect is also contributed to by the high full-width at half-maximum of the TDS spectrum. Therefore, it can be said that the D{sub 2} TDS spectra for Fe{sup 2+}-irradiated tungsten cannot represent that for the neutron-irradiated one, indicating that the deuterium trapping and desorption mechanism for neutron-irradiated tungsten is different from that for the ion-irradiated one.

Yasuhisa Oya; Masashi Shimada; Makoto Kobayashi; Takuji Oda; Masanori Hara; Hideo Watanabe; Yuji Hatano; Pattrick Calderoni; Kenji Okuno

2011-12-01

126

Effect of irradiation spectrum on the microstructure of ion-irradiated Al{sub 2}O{sub 3}  

SciTech Connect

Polycrystalline samples of alpha-alumina have been irradiated with various ions ranging from 3.6 MeV Fe{sup +} to 1 MeV H{sup +} ions at 650 C. Cross-section transmission electron microscopy was used to investigate the depth-dependent microstructure of the irradiated specimens. The microstructure following irradiation was observed to be dependent on the irradiation spectrum. In particular, defect cluster nucleation was effectively suppressed in specimens irradiated with light ions such as 1 MeV H{sup +} ions. On the other hand, light ion irradiation tended to accelerate the growth rate of dislocation loops. The microstructural observations are discussed in terms of ionization enhanced diffusion processes.

Zinkle, S.J. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1994-12-31

127

The effects of ion irradiation on porous silicon photoluminescence  

NASA Astrophysics Data System (ADS)

The effects of ion irradiation on porous Si (po-Si) photoluminescence (PL) are investigated to gain insight into the emission mechanism. Po-Si was obtained by standard electrochemical etching of p-doped Si(100) and the samples were aged for several weeks to achieve stability of the PL intensity. Specimens were progressively irradiated with H+, He+, or Ne++ ions followed by PL measurements. PL spectra were obtained as a function of the displacement per atom (DPA) parameter up to a DPA level of ˜10-2, which was sufficient to nearly extinguish PL. The quenching behavior showed a strong dependence on the chemical nature of the implanted species. Within experimental error, the quenching efficiency was equivalent for He+ and Ne++ irradiations, but was considerably higher for H+ irradiation. Channeling spectrometry showed the efficiency to be correlated with the self-recovery of defects generated during irradiation. The observed PL quenching is associated with the creation of nonradiative recombination sites within the band gap, but not with Si nanostructure amorphization and/or surface oxygen removal. Significant recovery of quenched PL occurs over a period of 120days for specimens that are stored in air, but not for samples that are stored in vacuum. These results demonstrate the importance and complexity of surface oxidation on the po-Si luminescence mechanism.

Jacobsohn, L. G.; Bennett, B. L.; Cooke, D. W.; Muenchausen, R. E.; Nastasi, M.

2005-02-01

128

Micromechanical tests of ion irradiated materials: Atomistic simulations and experiments  

SciTech Connect

We investigated irradiation effects on Fe-Cr binary alloys by using a nano-indentation combined with a continuous stiffness measurement (CSM) technique. We modeled the nano-indentation test by using a finite element method. We could extract the intrinsic hardness and the yield stress of an irradiation hardened region by using a so-called inverse method. SiC micro-pillars of various sizes were fabricated by mask and inductively coupled plasma etching technique and compressed by using flat punch nano-indentation. Compressive fracture strength showed a clear specimen size effect. Brittle-to-Ductile transition at room temperature was observed as the specimen size decreases. The effect of irradiation on the fracture strength of SiC micro-pillars was evaluated by performing ion irradiation with Si ions. We have performed molecular dynamics simulations of nano-indentation and nano-pillar compression tests. Radiation effect was observed which is found to be due to the interaction of dislocations nucleated by spherical indenter with pre-existing radiation defects (voids). These atomistic simulations are expected to significantly contribute to the investigation of the fundamental deformation mechanism of small scale irradiated materials. (authors)

Shin, C.; Jin, H. H.; Kwon, J. [Nuclear Materials Research Div., Korea Atomic Energy Research Inst., Daejeon, 305-353 (Korea, Republic of)

2012-07-01

129

Late degeneration in rabbit tissues after irradiation by heavy ions  

NASA Technical Reports Server (NTRS)

Results are presented for investigations of the late effects of heavy-ion irradiation on rabbit tissues which were undertaken to assess the hazards associated with the long-term exposure of humans to heavy ions in space during such activities as the construction of solar power stations or voyages to Mars. White rabbits approximately six weeks old were exposed to various doses of collimated beams of 400-MeV/n Ne ions, 570 MeV/n Ar ions and Co-60 gamma rays directed through both eyes, and the responses of the various tissues (hair follicles, skin, cornea, lens, retina, Harderian glands, bone and forebrain) were examined. Proliferating tissues are found to exhibit high damage levels in the early and late periods following irradiation, while terminally differentiating tissues repond to radiation most intensely in the late period, years after irradiation, with no intermediate recovery. The results obtained from rabbits are used to predict the occurrence of late tissue degeneration in the central nervous system, terminally differentiating systems and stem cells of humans one or more decades following exposure to radiation levels anticipated during long-duration space flights. The studies also indicate that tissues may be prematurely aged in the sense that tissue life spans may be shortened without the development of malignancies.

Lett, J. T.; Cox, A. B.; Keng, P. C.; Lee, A. C.; Su, C. M.; Bergtold, D. S.

1980-01-01

130

An IR study of pure and ion irradiated frozen formamide  

E-print Network

Context. The chemical evolution of formamide (HCONH2), a molecule of astrobiological interest that has been tentatively identified in interstellar ices and in cometary coma, has been studied in laboratory under simulated astrophysical conditions such as ion irradiation at low temperature. Aims. To evaluate the abundances of formamide observed in space or in laboratory, the integrated absorbances for all the principal IR features of frozen amorphous pure formamide deposited at 20 K were measured. Further evidence that energetic processing of ices occurring in space is extremely relevant both to astrochemistry and to astrobiology has been found, showing that new molecular species are synthesized by ion irradiation at a low temperature. Methods. Pure formamide were deposited at 20 K and IR transmission spectra measured for different ice thicknesses. The ice thickness was derived by looking at the interference pattern (intensity versus time) of a He-Ne laser beam reflected at an angle of 45 deg by the vacuum-film and film-substrate interfaces. Samples of formamide ice were irradiated with 200 keV H+ ions and IR spectra recorded at different ion fluences. Results. New molecules were synthesized among which are CO, CO2, N2O, isocyanic acid (HNCO), and ammonium cyanate (NH4+OCN-). Some of these species remain stable after warming up to room temperature.

John R. Brucato; Giuseppa A. Baratta; Giovanni Strazzulla

2006-04-28

131

Collisional activation of ions by off-resonance irradiation in ion cyclotron resonance spectrometry  

NASA Astrophysics Data System (ADS)

Collisional activation of ions in the ion cyclotron resonance (ICR) cell by short off-resonance burst irradiation (ORBI) was studied by time-resolved photodissociation of the meta-bromotoluene radical cation. Off-resonance chirp or single-frequency burst was applied for 2 ms to the probe ion in the presence of Ar buffer gas. The amount of internal energy imparted to the probe ion by collision under ORBI was precisely determined by time-resolved photodissociation spectroscopy. The rate of unimolecular dissociation of the probe ion following the photolysis at 532 nm was measured by monitoring the real-time appearance of the C7H7+ product ion. The internal energy of the probe ion was extracted from the known rate-energy curve. To help understand the collisional activation of an ion under ORBI, we simulated the radial trajectory of the ion using Green's method. The calculated radial kinetic energy was converted to the collision energy in the center-of-mass frame, and the collision frequency was estimated by using a reactive hard-sphere collision model with an ion-induced dipole potential. Both experiments and trajectory simulations suggest that chirp irradiation leads to less collisional activation of ions than other waveforms.

Shin, Seung Koo; Han, Seung-Jin; Seo, Jongcheol

2009-06-01

132

Magnetization and susceptibility of ion-irradiated granular magnetite films  

NASA Astrophysics Data System (ADS)

Porous granular films of magnetite (Fe3O4) with grains of ˜3 nm in size were prepared using a state-of-the-art nanocluster deposition system. The films are initially superparamagnetic but become magnetized following Si2+ ion irradiation. A significant increase in the grain size and a dramatic change in the microstructure are observed. There are dipolar interactions between the nanoparticles in both the unirradiated and irradiated films. The in-phase alternating current magnetic susceptibility of the unirradiated film shows a blocking temperature of ˜150 K, depending on frequency. A broadened Verwey transition for the irradiated film occurs at ˜75 K, above which the susceptibility exhibits unusual behavior: a nearly linear decrease with decreasing temperature. There are irreversible domain rotations in the irradiated film during zero-field cooling and warming cycles between 10 and 300 K. The observed behavior of the irradiated granular films is quite distinct from that of metallic nanostructures after irradiation, and is due to the dramatic change in microstructures.

Jiang, W.; McCloy, J. S.; Lea, A. S.; Sundararajan, J. A.; Yao, Q.; Qiang, Y.

2011-04-01

133

Magnetization and susceptibility of ion-irradiated granular magnetite films  

SciTech Connect

Porous granular films of magnetite (Fe{sub 3}O{sub 4}) with grains of {approx}3 nm in size were prepared using a state-of-the-art nanocluster deposition system. The films are initially superparamagnetic but become magnetized following Si{sup 2+} ion irradiation. A significant increase in the grain size and a dramatic change in the microstructure are observed. There are dipolar interactions between the nanoparticles in both the unirradiated and irradiated films. The in-phase alternating current magnetic susceptibility of the unirradiated film shows a blocking temperature of {approx}150 K, depending on frequency. A broadened Verwey transition for the irradiated film occurs at {approx}75 K, above which the susceptibility exhibits unusual behavior: a nearly linear decrease with decreasing temperature. There are irreversible domain rotations in the irradiated film during zero-field cooling and warming cycles between 10 and 300 K. The observed behavior of the irradiated granular films is quite distinct from that of metallic nanostructures after irradiation, and is due to the dramatic change in microstructures.

Jiang, W.; McCloy, J. S.; Lea, A. S.; Sundararajan, J. A.; Yao, Q.; Qiang, Y. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Physics Department, University of Idaho, Moscow, Idaho 83844 (United States)

2011-04-01

134

Magnetic properties of graphite irradiated with MeV ions  

SciTech Connect

We have studied the change in the magnetic properties produced on highly oriented pyrolytic graphite samples by irradiation of H, C, and N ions in the mega-electron-volt energy range. The use of specially made sample holders for the magnetic measurements provided high reproducibility allowing us to obtain directly the irradiation effects without any corrections or subtractions. Our results show that three magnetic phenomena are triggered by the defects produced by the irradiation, namely, Curie-type paramagnetism, ferromagnetism and an anomalous paramagnetic state that appears as precursor of the magnetic ordered state. Using SRIM simulations to estimate the amount of vacancies produced by the irradiation, the Curie-type paramagnetic response indicates an effective Bohr magneton number per nominally produced vacancy p=0.27+-0.02mu{sub B}. Direct measurements of the surface sample temperature during irradiation and the decrease in the (as-received) paramagnetic as well as ferromagnetic contributions after irradiation indicate that self-heating is one of the causes for small yield of ferromagnetism. Taking into account the hydrogen distribution in the virgin samples, the obtained results indicate that the induced ferromagnetism appears when the average vacancy distance is {approx}2 nm in the near surface region.

Ramos, M. A.; Munoz-Martin, A.; Climent-Font, A. [CMAM and Instituto de Ciencia de Materiales 'Nicolas Cabrera', Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Barzola-Quiquia, J.; Esquinazi, P. [Division of Superconductivity and Magnetism, Institut fuer Experimentelle Physik II, Universitaet Leipzig, Linnestrasse 5, D-04103 Leipzig (Germany); Garcia-Hernandez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid (Spain)

2010-06-01

135

Structure alterations in microporous (Mg,Fe){sub 2}Al{sub 4}Si{sub 5}O{sub 18} crystals induced by energetic heavy-ion irradiation  

SciTech Connect

The microporous framework structure of (Mg{sub 1-x}Fe{sub x}){sub 2}Al{sub 4}Si{sub 5}O{sub 18} (=cordierite) has been subject to a comparative study on the effect of structural alterations originating from exposure to high-energy heavy ions. Oriented samples (with x=0.061, 0.122, and 0.170) were irradiated with swift {sup 124}Xe, {sup 197}Au and {sup 96}Ru ions with 11.1 MeV per nucleon energy and fluences of 1x10{sup 12} and 1x10{sup 13} ions/cm{sup 2}. Irradiated and non-irradiated samples were investigated by means of X-ray diffraction, Moessbauer spectroscopy and optical absorption spectroscopy. Structural investigations reveal an essentially unchanged Al,Si ordering, which appears to be unaffected by irradiation. The most remarkable macroscopic change is the ion-beam induced colouration, which could be assigned to electronic charge transfer transitions involving the Fe cations. Moessbauer spectra indicate an increased amount of {sup [4]}Fe{sup 3+} for the irradiated sample. The most noticeable structural alteration concerns irradiation-induced dehydration of extra-framework H{sub 2}O, which is accompanied by a reduction in the molar volume by {approx}0.2 vol%. - Graphical abstract: Cordierite single-crystal specimen showing the color change from pale blue (unirradiated) to a yellowish brown layer (irradiated) after exposure to relativistic {sup 124}Xe ions at a fluence of 1x10{sup 12} ions per cm{sup 2}.

Miletich, Ronald, E-mail: ronald.miletich@geow.uni-heidelberg.d [Institut fuer Geowissenschaften, Universitaet Heidelberg, Im Neuenheimer Feld 234-236, D-69120 Heidelberg (Germany); Diego Gatta, G. [Dipartimento di Scienze della Terra, Universita degli Studi di Milano, Via Botticelli 23, I-20133 Milano (Italy); Redhammer, Guenther J. [Fachbereich Materialforschung und Physik, Abteilung Mineralogie, Universitaet Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg (Austria); Burchard, Michael; Meyer, Hans-Peter [Institut fuer Geowissenschaften, Universitaet Heidelberg, Im Neuenheimer Feld 234-236, D-69120 Heidelberg (Germany); Weikusat, Christian [Institut fuer Geowissenschaften, Universitaet Heidelberg, Im Neuenheimer Feld 234-236, D-69120 Heidelberg (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Materials Research, Planckstrasse 1, D-64291 Darmstadt (Germany); Rotiroti, Nicola [Dipartimento di Scienze della Terra, Universita degli Studi di Milano, Via Botticelli 23, I-20133 Milano (Italy); Glasmacher, Ulrich A. [Institut fuer Geowissenschaften, Universitaet Heidelberg, Im Neuenheimer Feld 234-236, D-69120 Heidelberg (Germany); Trautmann, Christina; Neumann, Reinhard [GSI Helmholtzzentrum fuer Schwerionenforschung, Materials Research, Planckstrasse 1, D-64291 Darmstadt (Germany)

2010-10-15

136

Vibrational spectra and structures of bare and Xe-tagged cationic SinOm+ clusters  

NASA Astrophysics Data System (ADS)

Vibrational spectra of Xe-tagged cationic silicon oxide clusters SinOm+ with n = 3-5 and m = n, n ± 1 in the gas phase are obtained by resonant infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory calculations. The SinOm+ clusters are produced in a laser vaporization ion source and Xe complexes are formed after thermalization to 100 K. The clusters are subsequently irradiated with tunable light from an IR free electron laser and changes in the mass distribution yield size-specific IR spectra. The measured IRMPD spectra are compared to calculated linear IR absorption spectra leading to structural assignments. For several clusters, Xe complexation alters the energetic order of the SinOm+ isomers. Common structural motifs include the Si2O2 rhombus, the Si3O2 pentagon, and the Si3O3 hexagon.

Savoca, Marco; Langer, Judith; Harding, Dan J.; Palagin, Dennis; Reuter, Karsten; Dopfer, Otto; Fielicke, André

2014-09-01

137

Metastable hydronium ions in UV-irradiated ice  

SciTech Connect

We show that the irradiation of UV light (10-11 eV) onto an ice film produces metastable hydronium (H{sub 3}O{sup +}) ions in the ice at low temperatures (53-140 K). Evidence of the presence of metastable hydronium ions was obtained by experiments involving adsorption of methylamine onto UV-irradiated ice films and hydrogen-deuterium (H/D) isotopic exchange reaction. The methylamine adsorption experiments showed that photogenerated H{sub 3}O{sup +} species transferred a proton to the methylamine arriving at the ice surface, thus producing the methyl ammonium ion, which was detected by low energy sputtering method. The H{sub 3}O{sup +} species induced the H/D exchange of water, which was monitored through the detection of water isotopomers on the surface by using the Cs{sup +} reactive ion scattering method. Thermal and temporal stabilities of H{sub 3}O{sup +} and its proton migration activity were examined. The lifetime of the hydronium ions in the amorphized ice was greater than 1 h at {approx}53 K and decreased to {approx}5 min at 140 K. Interestingly, a small portion of hydronium ions survived for an extraordinarily long time in the ice, even at 140 K. The average migration distance of protons released from H{sub 3}O{sup +} in the ice was estimated to be about two water molecules at {approx}54 K and about six molecules at 100 K. These results indicate that UV-generated hydronium ions can be efficiently stabilized in low-temperature ice. Such metastable hydronium ions may play a significant role in the acid-base chemistry of ice particles in interstellar clouds.

Moon, Eui-Seong; Kang, Heon [Department of Chemistry, Seoul National University, 1 Gwanak-ro, Seoul 151-747 (Korea, Republic of)

2012-11-28

138

Mutagenic effects of heavy ion irradiation on rice seeds  

NASA Astrophysics Data System (ADS)

Three varieties of rice seeds were subjected to irradiation using low-energy and medium-energy ions. The damage and mutations induced by the ions were examined. In addition, genetic analysis and gene mapping of spotted leaf (spl) mutants were performed. Low-energy ions had no significant influence on germination, survival or seedling height, except for the survival of Nipponbare. Medium-energy ions had a significant influence on germination and survival but had no significant effect on seedling height. In the low-energy group, among 60,000 M2 plants, 2823 putative morphological mutants were found, and the mutation frequency was approximately 4.71%. In the medium-energy group, 3132 putative morphological mutants were found, and the mutation frequency was approximately 5.22%. Five spl mutants (spl29-spl33) were obtained by ion irradiation, and the heredity of the spl mutants was stable. The characteristics of the spl mutants were found, by genetic analysis and preliminary mapping, to be controlled by a single recessive gene, and spl30 and spl33 were found to be new lesion-mimic mutants.

Xu, Xue; Liu, Binmei; Zhang, Lili; Wu, Yuejin

2012-11-01

139

(Grain boundary and interface kinetics during ion irradiation)  

SciTech Connect

Proposed here is renewed support of a research program focused on interface motion and phase transformation during ion irradiation, with emphasis on elemental semiconductors. Broadly speaking, the aims of this program are to explore defect kinetics in amorphous and crystalline semiconductors, and to relate defect dynamics to interface motion and phase transformations. Over the last three years, we initiated a program under DOE support to explore crystallization and amorphization of elemental semiconductors under irradiation. This research has enabled new insights about the nature of defects in amorphous semiconductors and about microstructural evolution in the early stages of crystallization. In addition, we have demonstrated almost arbitrary control over the relative rates of crystal nucleation and crystal growth in silicon. As a result, the impinged grain microstructure of thin (100 nm) polycrystalline films crystallized under irradiation can be controlled with grain sizes ranging from a few nanometers to several micrometers, which may have interesting technological implications.

Atwater, H.A.

1991-01-01

140

[Grain boundary and interface kinetics during ion irradiation  

SciTech Connect

Proposed here is renewed support of a research program focused on interface motion and phase transformation during ion irradiation, with emphasis on elemental semiconductors. Broadly speaking, the aims of this program are to explore defect kinetics in amorphous and crystalline semiconductors, and to relate defect dynamics to interface motion and phase transformations. Over the last three years, we initiated a program under DOE support to explore crystallization and amorphization of elemental semiconductors under irradiation. This research has enabled new insights about the nature of defects in amorphous semiconductors and about microstructural evolution in the early stages of crystallization. In addition, we have demonstrated almost arbitrary control over the relative rates of crystal nucleation and crystal growth in silicon. As a result, the impinged grain microstructure of thin (100 nm) polycrystalline films crystallized under irradiation can be controlled with grain sizes ranging from a few nanometers to several micrometers, which may have interesting technological implications.

Atwater, H.A.

1991-12-31

141

He ion irradiation damage to Al/Nb multilayers  

SciTech Connect

We investigated the evolution of microstructure and mechanical properties of sputter-deposited Al/Nb multilayers with individual layer thickness, h, of 1-200 nm, subjected to helium ion irradiations: 100 keV He{sup +} ions with a dose of 6 x 10{sup 16}/cm{sup 2}. Helium bubbles, 1-2 nm in diameter, were observed. When h is greater than 25 nm, hardnesses of irradiated multilayers barely change, whereas radiation hardening is more significant at smaller h. Transmission electron microscopy and scanning transmission electron microscopy studies reveal the formation of a thin layer of Nb{sub 3}Al intermetallic along the Al/Nb interface as a consequence of radiation induced intermixing. The dependence of radiation hardening on h is interpreted by using a composite model considering the formation of the hard Nb{sub 3}Al intermetallic layer.

Misra, Amit [Los Alamos National Laboratory; Li, Nan [TEXAS A& M; Martin, M S [TEXAS A& M; Anderoglu, Osman [TEXAS A& M; Shao, L [TEXAS A& M; Wang, H [TEXAS A& M; Zhang, X [TEXAS A& M

2009-01-01

142

Translational energy dependence of reaction mechanism: Xe++CH4?XeH++CH3  

E-print Network

The dynamics of the exoergic ion–molecule reaction Xe+(CH4,CH3)XeH+ were studied by chemical accelerator techniques over the relative translational energy range 0.2 to 8 eV. Results of the kinematicmeasurements are reported as scattering intensity...

Miller, G. D.; Strattan, L. W.; Cole, C. L.; Hierl, Peter M.

1981-01-01

143

Magnetization and susceptibility of ion-irradiated granular magnetite films  

Microsoft Academic Search

Porous granular films of magnetite (Fe3O4) with grains of ˜3 nm in size were prepared using a state-of-the-art nanocluster deposition system. The films are initially superparamagnetic but become magnetized following Si2+ ion irradiation. A significant increase in the grain size and a dramatic change in the microstructure are observed. There are dipolar interactions between the nanoparticles in both the unirradiated

Weilin Jiang; John S. McCloy; Alan S. Lea; J. A. Sundararajan; Qi Yao; Y. Qiang

2011-01-01

144

Respiratory gated irradiation system for heavy-ion radiotherapy  

Microsoft Academic Search

Purpose: In order to reduce the treatment margin of the moving target due to breathing, we developed a gated irradiation system for heavy-ion radiotherapy.Methods and Materials: The motion of a patient due to respiration is detected by the motion of the body surface around the chest wall. A respiratory sensor was developed using an infrared light spot and a position-sensitive

Shinichi Minohara; Tatsuaki Kanai; Masahiro Endo; Kouji Noda; Mitsutaka Kanazawa

2000-01-01

145

Ion irradiation induced structural and electrical transition in graphene  

SciTech Connect

The relationship between the electrical properties and structure evolution of single layer graphene was studied by gradually introducing the gallium ion irradiation. Raman spectrums show a structural transition from nano-crystalline graphene to amorphous carbon as escalating the degree of disorder of the graphene sample, which is in correspondence with the electrical transition from a Boltzmann diffusion transport to a carrier hopping transport. The results show a controllable method to tune the properties of graphene.

Zhou Yangbo; Wang Yifan; Xu Jun; Fu Qiang; Wu Xiaosong; Yu Dapeng [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Liao Zhimin [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College, Dublin 2 (Ireland); Duesberg, Georg S. [Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College, Dublin 2 (Ireland); School of Chemistry, Trinity College, Dublin 2 (Ireland)

2010-12-21

146

Heavy ion tracks in polycarbonate. Comparison with a heavy ion irradiated model compound (diphenyl carbonate)  

NASA Astrophysics Data System (ADS)

The chemical modifications induced by energetic heavy ion irradiation of polycarbonate (PC) film are determined by GPC, HPLC, ESR, TGA, IR and UV spectrophotometry. The main results of the irradiation are creation of radicals, chain scission, cross-linking and appearance of new chemical groups in the main polymer chain. As far as the creation of new groups is concerned, they are determined by means of a model compound of PC: the diphenyl carbonate (DPC). The following compounds are identified after energetic heavy ion irradiation of DPC: salicylic acid, phenol, 4,4'-biphenol, 2,4'-biphenol, 2,2'-biphenol, 4-phenoxyphenol, 2-phenoxyphenol, phenyl ether, phenyl benzoate, phenyl salicylate, 2-phenylphenol and 2-phenoxyphenyl benzoate. A similarity between the heavy ion irradiation and a heat treatment has also been established with DPC. On the basis of these results, we try to give an explanation of the preferential attack along the tracks of the irradiated film. Also, an explanation of the well-known beneficial effect of an UV exposition of the irradiated film on the selectivity of this preferential chemical attack is suggested.

Ferain, E.; Legras, R.

1993-09-01

147

Manipulation of the graphene surface potential by ion irradiation  

NASA Astrophysics Data System (ADS)

We show that the work function of exfoliated single layer graphene can be modified by irradiation with swift (Ekin=92 MeV) heavy ions under glancing angles of incidence. Upon ion impact individual surface tracks are created in graphene on silicon carbide. Due to the very localized energy deposition characteristic for ions in this energy range, the surface area which is structurally altered is limited to ?0.01 ?m2 per track. Kelvin probe force microscopy reveals that those surface tracks consist of electronically modified material and that a few tracks suffice to shift the surface potential of the whole single layer flake by ?400 meV. Thus, the irradiation turns the initially n-doped graphene into p-doped graphene with a hole density of 8.5×1012 holes/cm2. This doping effect persists even after heating the irradiated samples to 500 °C. Therefore, this charge transfer is not due to adsorbates but must instead be attributed to implanted atoms. The method presented here opens up a way to efficiently manipulate the charge carrier concentration of graphene.

Ochedowski, O.; Kleine Bussmann, B.; Ban d'Etat, B.; Lebius, H.; Schleberger, M.

2013-04-01

148

Manipulation of the graphene surface potential by ion irradiation  

SciTech Connect

We show that the work function of exfoliated single layer graphene can be modified by irradiation with swift (E{sub kin}=92 MeV) heavy ions under glancing angles of incidence. Upon ion impact individual surface tracks are created in graphene on silicon carbide. Due to the very localized energy deposition characteristic for ions in this energy range, the surface area which is structurally altered is limited to Almost-Equal-To 0.01 {mu}m{sup 2} per track. Kelvin probe force microscopy reveals that those surface tracks consist of electronically modified material and that a few tracks suffice to shift the surface potential of the whole single layer flake by Almost-Equal-To 400 meV. Thus, the irradiation turns the initially n-doped graphene into p-doped graphene with a hole density of 8.5 Multiplication-Sign 10{sup 12} holes/cm{sup 2}. This doping effect persists even after heating the irradiated samples to 500 Degree-Sign C. Therefore, this charge transfer is not due to adsorbates but must instead be attributed to implanted atoms. The method presented here opens up a way to efficiently manipulate the charge carrier concentration of graphene.

Ochedowski, O.; Kleine Bussmann, B.; Schleberger, M. [Fakultaet fuer Physik and CeNIDE, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany)] [Fakultaet fuer Physik and CeNIDE, Universitaet Duisburg-Essen, D-47048 Duisburg (Germany); Ban d'Etat, B.; Lebius, H. [CIMAP (CEA-CNRS-ENSICAEN-UCBN), 14070 Caen Cedex 5 (France)] [CIMAP (CEA-CNRS-ENSICAEN-UCBN), 14070 Caen Cedex 5 (France)

2013-04-15

149

Defect production and accumulation under hydrogen and helium ion irradiation  

NASA Astrophysics Data System (ADS)

The 316L stainless steel (316L SS) is a candidate material for the first wall of a fusion reactor, which will be irradiated with 14 MeV neutrons and escaped ions. This will produce helium and hydrogen in the matrix, which come both from the transmutation production and escaped ions of the plasma. The synergistic action of high-energy cascades and helium induces important damage, such as swelling, blistering and helium embrittlement. The hydrogen combines with the radiation defects to produce dense tiny bubbles (or voids) and substitutes for gaseous impurities (such as soluted oxygen, nitrogen, sulfur and phosphorus) which react with other composites Fe, Cr, Ni and Mo to form new phases, such as Cr 2O 3, (CrFe) 2O 3, (Fe 5C 2)28N, (CrMo)N, (Fe 2Mo)12H and (FeNi) 9S 8. These induce mechanical property changes. The hydrogen combined with helium and high energy cascades will induce more serious damage than that of helium alone. To exhibit the synergistic action of helium and hydrogen, the 316L SS specimens were bombarded with helium, hydrogen and mixed ion beam with energy ranging from 27 to 38 keV to a dose of 10 17-8 × 10 18 ions/cm 2 at 573 K. The results indicate that (a) for the helium ion irradiation, the threshold dose for blistering in the energy range 27-100 keV is higher than that for the 1.0 MeV helium ion irradiation. The surface effects play an important role in the blistering. (b) When specimens bombarded with the mixed beam of helium and hydrogen ions of 27 keV reached the same helium dose (6.4 × 10 17 He +/cm 2), the diameter and density of bubble on surface increase at a ratio of the hydrogen to helium increase. The more hydrogen ions implanted, the easier and more serious the blister is. (c) When the kinetic energy of the mixed beam decreases in the range 10-30 keV, the action of hydrogen ions on the blistering appears more evident. It seems that the hydrogen plays an important role in bubble formation and growth.

Yu, Jinnan; Zhao, Xinjie; Zhang, Wen; Yang, Wen; Chu, Fengmin

1997-11-01

150

Light ion irradiation for unfavorable soft tissue sarcoma  

SciTech Connect

Between 1978 and 1989, 32 patients with unfavorable soft tissue sarcoma underwent light ion (helium, neon) irradiation with curative intent at Lawrence Berkeley Laboratory. The tumors were located in the trunk in 22 patients and head and neck in 10. Macroscopic tumor was present in 22 at the time of irradiation. Two patients had tumors apparently induced by previous therapeutic irradiation. Follow-up times for surviving patients ranged from 4 to 121 months (median 27 months). The overall 3-year actuarial local control rate was 62%; the corresponding survival rate was 50%. The 3-year actuarial control rate for patients irradiated with macroscopic tumors was 48%, while none of the patients with microscopic disease developed local recurrence (100%). The corresponding 3-year actuarial survival rates were 40% (macroscopic) and 78% (microscopic). Patients with retroperitoneal sarcoma did notably well; the local control rate and survival rate were 64% and 62%, respectively. Complications were acceptable; there were no radiation related deaths, while two patients (6%) required operations to correct significant radiation-related injuries. These results appear promising compared to those achieved by low -LET irradiation, and suggest that this technique merits further investigation.

Linstadt, D.; Castro, J.R.; Phillips, T.L.; Petti, P.L.; Collier, J.M.; Daftari, I.; Schoethaler, R.; Rayner, A.

1990-09-01

151

Synthesis of embedded Au nanostructures by ion irradiation: influence of ion induced viscous flow and sputtering  

PubMed Central

Summary The ion-irradiation induced synthesis of embedded Au nanoparticles (NPs) into glass from islands of Au on a glass substrate is studied in the context of recoiling atoms, sputtering and viscous flow. Cross sectional transmission electron microscopy studies revealed the formation of Au NPs embedded in the glass substrates by the 50 keV Si? ion irradiation of irregularly shaped Au nanostructures on the glass surfaces at a fluence of 3 × 1016 ions/cm2. The depth profiles of Au in the samples were obtained from high-resolution Rutherford backscattering spectrometry studies. The results from TRIDYN simulation reveal the role of various ion-induced processes during the synthesis of the embedded Au NPs, viz. sputtering and recoiling atoms. Simulation and experimental results suggest that the viscous flow is one of the major factors that are responsible for the embedding of Au nanoparticles into the glass substrate. PMID:24605276

Agarwal, D C; Khan, S A; Mohapatra, S; Amekura, H; Datta, D P; Kumar, Ajay; Choudhury, R K; Chan, T K; Osipowicz, Thomas; Avasthi, D K

2014-01-01

152

Synthesis of embedded Au nanostructures by ion irradiation: influence of ion induced viscous flow and sputtering.  

PubMed

The ion-irradiation induced synthesis of embedded Au nanoparticles (NPs) into glass from islands of Au on a glass substrate is studied in the context of recoiling atoms, sputtering and viscous flow. Cross sectional transmission electron microscopy studies revealed the formation of Au NPs embedded in the glass substrates by the 50 keV Si(-) ion irradiation of irregularly shaped Au nanostructures on the glass surfaces at a fluence of 3 × 10(16) ions/cm(2). The depth profiles of Au in the samples were obtained from high-resolution Rutherford backscattering spectrometry studies. The results from TRIDYN simulation reveal the role of various ion-induced processes during the synthesis of the embedded Au NPs, viz. sputtering and recoiling atoms. Simulation and experimental results suggest that the viscous flow is one of the major factors that are responsible for the embedding of Au nanoparticles into the glass substrate. PMID:24605276

Singh, Udai B; Agarwal, D C; Khan, S A; Mohapatra, S; Amekura, H; Datta, D P; Kumar, Ajay; Choudhury, R K; Chan, T K; Osipowicz, Thomas; Avasthi, D K

2014-01-01

153

Origins of ion irradiation-induced Ga nanoparticle motion on GaAs surfaces  

SciTech Connect

We have examined the origins of ion irradiation-induced nanoparticle (NP) motion. Focused-ion-beam irradiation of GaAs surfaces induces random walks of Ga NPs, which are biased in the direction opposite to that of ion beam scanning. Although the instantaneous NP velocities are constant, the NP drift velocities are dependent on the off-normal irradiation angle, likely due to a difference in surface non-stoichiometry induced by the irradiation angle dependence of the sputtering yield. It is hypothesized that the random walks are initiated by ion irradiation-induced thermal fluctuations, with biasing driven by anisotropic mass transport.

Kang, M.; Wu, J. H.; Chen, H. Y.; Thornton, K.; Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Sofferman, D. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Adelphi University, Garden City, New York 11530-0701 (United States); Beskin, I. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

2013-08-12

154

Ion irradiation damage in ilmenite under cryogenic conditions  

SciTech Connect

A natural single crystal of ilmenite was irradiated at 100 K with 200 keV Ar{sup 2+}. Rutherford backscattering spectroscopy and ion channeling with 2 MeV He{sup +} ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 {times} 10{sup 15} Ar{sup 2+} cm{sup {minus}2}, considerable near-surface He{sup +} ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 mm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO{sub 3}) and spinel (MgAl{sub 2}O{sub 4}) to explore factors that may influence radiation damage response in oxides.

Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Nord, G.L. Jr. [Geological Survey, Reston, VA (United States)

1996-11-01

155

Ion irradiation damage in ilmenite at 100 K  

SciTech Connect

A natural single crystal of ilmenite (FeTiO{sub 3}) was irradiated at 100 K with 200 keV Ar{sup 2+}. Rutherford backscattering spectroscopy and ion channeling with MeV He{sup +} ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 {times} 10{sup 15} Ar{sup 2+} cm{sup {minus}2}, considerable near-surface He{sup +} ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 nm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO{sub 3}) and spinel (MgAl{sub 2}O{sub 4}) to explore factors that may influence radiation damage response in oxides.

Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Nord, G.L. Jr. [Geological Survey, Reston, VA (United States)

1997-10-01

156

Ion irradiation damage in ilmenite at 100 K  

USGS Publications Warehouse

A natural single crystal of ilmenite (FeTiO3) was irradiated at 100 K with 200 keV Ar2+. Rutherford backscattering spectroscopy and ion channeling with 2 MeV He+ ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 ?? 1015 Ar2+/cm2, considerable near-surface He+ ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 nm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO3) and spinel (MgAl2O4) to explore factors that may influence radiation damage response in oxides.

Mitchell, J.N.; Yu, N.; Devanathan, R.; Sickafus, K.E.; Nastasi, M.A.; Nord, G.L., Jr.

1997-01-01

157

Nanoscale manipulation of Ge nanowires by ion irradiation  

SciTech Connect

Nanowires have generated considerable interest as nanoscale interconnects and as active components of both electronic and electromechanical devices. However, in many cases, manipulation and modification of nanowires are required to fully realize their potential. It is essential, for instance, to control the orientation and positioning of nanowires in some specific applications. This work demonstrates a simple method to reversibly control the shape and the orientation of Ge nanowires using ion beams. Crystalline nanowires were amorphized by 30 keV Ga{sup +} implantation. Subsequently, viscous flow and plastic deformation occurred causing the nanowires to bend toward the beam direction. The bending was reversed multiple times by ion implanting the opposite side of the nanowires, resulting in straightening and subsequent bending into that opposite direction. This effect demonstrates the detailed manipulation of nanoscale structures is possible through the use of ion irradiation.

Romano, Lucia [Department of Physics and Astronomy, University of Catania and MATIS CNR-INFM, 64 Via S. Sofia, I-95123 Catania (Italy); Rudawski, Nicholas G.; Holzworth, Monta R.; Jones, Kevin S. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Choi, S. G.; Picraux, S. T. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2009-12-01

158

Study of ion-irradiated tungsten in deuterium plasma  

NASA Astrophysics Data System (ADS)

Experimental study aimed at investigation of neutron induced damage influence on fusion reactor plasma facing materials is reported. Displacement damage was produced in tungsten by high-energy helium and carbon ions at 3-10 MeV. The reached level of displacement damage ranged from several dpa to 600 dpa. The properties of the irradiated tungsten were studied in steady-state deuterium plasma on the LENTA linear divertor simulator. Plasma exposures were made at 250 eV of ion energy to fluence 1021-1022 ion/?m2. Erosion dynamics of the damaged layer and deuterium retention were observed. Surface microstructure modifications and important damage of the 5 ?m layer shown. Deuterium retention in helium-damaged tungsten (ERD) showed its complex behavior (increase or decrease) depending on implanted helium quantity and the structure of the surface layer.

Khripunov, B. I.; Gureev, V. M.; Koidan, V. S.; Kornienko, S. N.; Latushkin, S. T.; Petrov, V. B.; Ryazanov, A. I.; Semenov, E. V.; Stolyarova, V. G.; Danelyan, L. S.; Kulikauskas, V. S.; Zatekin, V. V.; Unezhev, V. N.

2013-07-01

159

Swift heavy ion irradiation of Pt nanocrystals: I. shape transformation and dissolution  

SciTech Connect

We report on the effects of swift heavy ion irradiation of embedded Pt nanocrystals (NCs), which change from spheres to prolate spheroids to rods upon irradiation. Using a broad range of ion irradiation energies and NC mean sizes we demonstrate that the elongation and dissolution processes are energy and size dependent, attaining comparable levels of shape transformation and dissolution upon a given energy density deposited in the matrix. The NC shape transformation remains operative despite discontinuous ion tracks in the matrix and exhibits a constant threshold size for elongation. In contrast, for ion irradiations in which the ion tracks are continuous, the threshold size for elongation is clearly energy dependent.

Giulian, R.; Araujo, L.L.; Kluth, P.; Sprouster, D.J.; Schnohr, C.S.; Byrne, A.P.; Ridgway, M.C. (ANU)

2014-09-24

160

Response of synthetic coffinite to energetic ion beam irradiation  

NASA Astrophysics Data System (ADS)

Coffinite, USiO 4, is one of the two most abundant and important naturally occurring U 4+ phases (the other is UO 2), and it is an alteration product of the UO 2 in spent nuclear fuel when in contact with silica-rich groundwater under reducing conditions. Despite its ubiquity, there are very limited data on the response of coffinite to radiation. Here, we present the results of the first systematic investigation of energetic ion beam irradiation (1 MeV Kr 2+) of ultra-fine, synthetic coffinite (20-50 nm). In situ transmission electron microscopy (TEM) showed that the crystalline-to-amorphous transformation occurs at a relatively low dose, ˜0.27 displacements per atom (dpa) at room temperature. The critical temperature, T c, above which coffinite cannot be amorphized, is low (˜608 K). Synthetic coffinite is more stable as compared with isostructural zircon (ZrSiO 4; T c = 1000 K) and thorite (ThSiO 4; T c above 1100 K) upon ion beam irradiation at elevated temperature, suggesting enhanced defect annealing behavior in nano-sized synthetic coffinite. Irradiation was found to decrease the temperature required to induce phase decomposition process in coffinite upon thermal annealing. A good correlation among the critical amorphization temperature, T c, phase decomposition temperature, T f, and the temperature range of the two-phase (ZrO 2 and SiO 2) co-existed region was identified.

Lian, J.; Zhang, J. M.; Pointeau, V.; Zhang, F. X.; Lang, M.; Lu, F. Y.; Poinssot, C.; Ewing, R. C.

2009-09-01

161

Microstructure of RERTR DU-Alloys Irradiated with Krypton Ions  

SciTech Connect

Fuel development for reduced enrichment research and test reactor (RERTR) program is tasked with the development of new low enrichment uranium fuels that can be employed to replace existing high enrichment uranium fuels currently used in many research and test reactors worldwide. Radiation stability of the interaction product formed at fuel-matrix interface has a strong impact on fuel performance. Three depleted uranium alloys are cast that consist of the following 5 phases of interest to be investigated: U(Si,Al)3, (U,Mo)(Si,Al)3, UMo2Al20, U6Mo4Al43 and UAl4. Irradiation of TEM disc samples with 500 keV Kr ions at 200?C to high doses up to ~100 dpa were conducted using an intermediate voltage electron microscope equipped with an ion accelerator. The irradiated microstructure of the 5 phases is characterized using transmission electron microscopy. The results will be presented and the implication of the observed irradiated microstructure on the fuel performance will be discussed.

J. Gan; D. Keiser; D. Wachs; B. Miller; T. Allen; M. Kirk; J. Rest

2009-11-01

162

Ion irradiation-induced amorphization and nano-crystal formation in garnets  

E-print Network

Ion irradiation-induced amorphization and nano-crystal formation in garnets S. Utsunomiya a , L ion irradiation of the G3 garnet at a temperature of 1023 K near the Tc, nano-crystals were produced, particularly yttrium aluminum garnet (YAG), Y3Al5O12, and YAG doped by other ions for use in laser systems

Utsunomiya, Satoshi

163

Amorphization of -Thorium Phosphate Diphosphate (-TPD) irradiated with high energy krypton ions  

E-print Network

Amorphization of -Thorium Phosphate Diphosphate (-TPD) irradiated with high energy krypton ions C the irradiation of -TPD with 840-MeV krypton ions. In storage conditions, the energy of both -particles and recoil nuclei is much lower (see above). However, the high energy of krypton ions was chosen with the double aim

Paris-Sud XI, Université de

164

Ion mass dependence of irradiation-induced local creation of ferromagnetism in Fe{sub 60}Al{sub 40} alloys  

SciTech Connect

Ion irradiation of Fe{sub 60}Al{sub 40} alloys results in the phase transformation from the paramagnetic, chemically ordered B2 phase to the ferromagnetic, chemically disordered A2 phase. The magnetic phase transformation is related to the number of displacements per atom (dpa) during the irradiation. For heavy ions (Ar{sup +}, Kr{sup +}, and Xe{sup +}), a universal curve is observed with a steep increase in the fraction of the ferromagnetic phase that reaches saturation, i.e., a complete phase transformation, at about 0.5 dpa. This proves the purely ballistic nature of the disordering process. If light ions are used (He{sup +} and Ne{sup +}), a pronounced deviation from the universal curve is observed. This is attributed to bulk vacancy diffusion from the dilute collision cascades, which leads to a partial recovery of the thermodynamically favored B2 phase. Comparing different noble gas ion irradiation experiments allows us to assess the corresponding counteracting contributions. In addition, the potential to create local ferromagnetic areas embedded in a paramagnetic matrix is demonstrated.

Fassbender, J.; Liedke, M. O.; Strache, T.; Moeller, W.; Menendez, E.; Sort, J.; Rao, K. V.; Deevi, S. C.; Nogues, J. [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, P.O. Box 51 01 19, 01314 Dresden (Germany); Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Institucio Catalana de Recerca i Estudis Avancats (ICREA) and Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Department of Materials Science and Engineering, Royal Institute of Technology, S-10044 Stockholm (Sweden); Research Center, Chrysalis Technologies Incorporated, Richmond, Virginia 23234 (United States); Institucio Catalana de Recerca i Estudis Avancats (ICREA) and Institut Catala de Nanotecnologia, Edifici CM7, Campus Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)

2008-05-01

165

Net sputtering rate due to hot ions in a Ne-Xe discharge gas bombarding an MgO layer  

SciTech Connect

An analytical method is developed for determining net sputtering rate for an MgO layer under hot ions with low energy (<100 eV) in a neon-xenon discharge gas at near-atmospheric pressure. The primary sputtering rate is analyzed according to spatial and energy distributions of the hot ions with average energy, E{sup h}{sub i}, above a threshold energy of sputtering, E{sub th,i}, multiplied by a yield coefficient. The threshold energy of sputtering is determined from dissociation energy required to remove an atom from MgO surface multiplied by an energy-transfer coefficient. The re-deposition rate of the sputtered atoms is calculated by a diffusion simulation using a hybridized probabilistic and analytical method. These calculation methods are combined to analyze the net sputtering rate. Maximum net sputtering rate due to the hot neon ions increases above the partial pressure of 4% xenon as E{sup h}{sub Ne} becomes higher and decreases near the partial pressure of 20% xenon as ion flux of neon decreases. The dependence due to the hot neon ions on partial pressure and applied voltage agrees well with experimental results, but the dependence due to the hot xenon ions deviates considerably. This result shows that the net sputtering rate is dominated by the hot neon ions. Maximum E{sup h}{sub Ne} (E{sup h}{sub Ne,max} = 5.3 - 10.3 eV) is lower than E{sub th,Ne} (19.5 eV) for the MgO layer; therefore, weak sputtering due to the hot neon ions takes place. One hot neon ion sputters each magnesium and each oxygen atom on the surface and distorts around a vacancy. The ratio of the maximum net sputtering rate is approximately determined by number of the ions at E{sup h}{sub i,max} multiplied by an exponential factor of -E{sub th,i}/E{sup h}{sub i,max}.

Ho, S.; Tamakoshi, T.; Ikeda, M.; Mikami, Y.; Suzuki, K. [Advanced Research Laboratory, Hitachi, Ltd., Akanuma 2520, Hatoyama-machi, Saitama 350-0395 (Japan)

2011-04-15

166

Self-aligned nanostructures created by swift heavy ion irradiation  

SciTech Connect

In tetrahedral amorphous carbon (ta-C) swift heavy ions create conducting tracks of about 8 nm in diameter. To apply these nanowires and implement them into nanodevices, they have to be contacted and gated. In the present work, we demonstrate the fabrication of conducting vertical nanostructures in ta-C together with self-aligned gate electrodes. A multilayer assembly is irradiated with GeV heavy ions and subsequently exposed to several selective etching processes. The samples consist of a Si wafer as substrate covered by a thin ta-C layer. On top is deposited a SiN{sub x} film for insulation, a Cr layer as electrode, and finally a polycarbonate film as ion track template. Chemical track etching opens nanochannels in the polymer which are self-aligned with the conducting tracks in ta-C because they are produced by the same ions. Through the pores in the polymer template, the Cr and SiN{sub x} layers are opened by ion beam sputtering and plasma etching, respectively. The resulting structure consists of nanowires embedded in the insulating carbon matrix with a built in gate electrode and has potential application as gated field emission cathode.

Gehrke, Hans-Gregor; Nix, Anne-Katrin; Hofsaess, Hans [2. Physikalisches Institut, Universitaet Goettingen, Friedrich-Hundplatz 1, D-37077 Goettingen (Germany); Krauser, Johann [Hochschule Harz, Friedrichstrasse 57-59, D-38855 Wernigerode (Germany); Trautmann, Christina [GSI Helmholzzentrum fuer Schwerionenforschung, Planckstr. 1, D-64291 Darmstadt (Germany); Weidinger, Alois [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany)

2010-05-15

167

Microcracks in ~ 100 MeV Si7+-ION-IRRADIATED p-SILICON Surfaces  

NASA Astrophysics Data System (ADS)

The p-silicon surfaces have been irradiated with ~ 100 MeV Si7+ions to a fluence of 2.2×1013 ions cm-2, and surface morphology has been studied with atomic force microscopy (AFM). Interesting features of cracks of ~ 47 nm in depth and ~ 103 nm in width on the irradiated surfaces have been observed. The observed features seemed to have been caused by the irradiation-induced stress in the irradiated regions of the target surface.

Sinha, O. P.; Srivastava, P. C.; Ganesan, V.

168

The discrepancies in multistep damage evolution of yttria-stabilized zirconia irradiated with different ions  

SciTech Connect

This paper reports a comprehensive investigation of structural damage in yttria-stabilized zirconia irradiated with different ions over a wide fluence range. A similar multistep damage accumulation exists for the irradiations of different ions, but the critical doses for occurrence of second damage step, characterized by a faster increase in damage fraction, and the maximum elastic strain at the first damage step are varied and depend on ion mass. For irradiations of heavier ions, the second damage step occurs at a higher dose with a lower critical elastic strain. Furthermore, larger extended defects were observed in the irradiations of heavy ions at the second damage step. Associated with other experiment results and multistep damage accumulation model, the distinct discrepancies in the damage buildup under irradiations of different ions were interpreted by the effects of electronic excitation, energy of primary knock-on atom and chemistry contributions of deposited ions.

Yang, Tengfei [Peking University; Taylor, Caitlin A. [University of Tennessee, Knoxville (UTK); Kong, Shuyan [Peking University; Wang, Chenxu [Peking University; Zhang, Yanwen [ORNL; Huang, Xuejun [Peking University; Xue, Jianming [Peking University; Yan, Sha [Peking University; Wang, Yugang [Peking University

2013-01-01

169

Neovascular glaucoma after helium ion irradiation for uveal melanoma  

SciTech Connect

Neovascular glaucoma developed in 22 of 169 uveal melanoma patients treated with helium ion irradiation. Most patients had large melanomas; no eyes containing small melanomas developed anterior segment neovascularization. The mean onset of glaucoma was 14.1 months (range, 7-31 months). The incidence of anterior segment neovascularization increased with radiation dosage; there was an approximately three-fold increase at 80 GyE versus 60 GyE of helium ion radiation (23% vs. 8.5%) (P less than 0.05). Neovascular glaucoma occurred more commonly in larger tumors; the incidence was not affected by tumor location, presence of subretinal fluid, nor rate of tumor regression. Fifty-three percent of patients had some response with intraocular pressures of 21 mmHg or less to a combination of antiglaucoma treatments.

Kim, M.K.; Char, D.H.; Castro, J.L.; Saunders, W.M.; Chen, G.T.; Stone, R.D.

1986-02-01

170

The change of microstructure and thermal properties in ion irradiated carbon nanotube mats as a function of ion penetration depth  

SciTech Connect

A stack of three carbon nanotube (CNT) mats was irradiated with 3 MeV He ions. The change in structural and thermal properties of individual mats as a function of ion penetration depth was characterized using electron microscopy and laser flash techniques. Ion irradiation can enhance thermal conductivity of the mats by introducing inter-tube displacements, which improve phonon transport across adjacent nanotubes. The enhancement, however, is reduced at higher damage levels due to the increasing phonon-defect scattering within the tubes. This study demonstrates the feasibility of using ion irradiation to manipulate thermal transport in carbon nanotubes.

Aitkaliyeva, A. [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States)] [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); Shao, L. [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States) [Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843 (United States); Department of Nuclear Engineering, Texas A and M University, College Station, Texas 77843 (United States)

2013-02-11

171

Detection of DNA damage induced by heavy ion irradiation in the individual cells with comet assay  

NASA Astrophysics Data System (ADS)

Investigating the biological effects of high-LET heavy ion irradiation at low fluence is important to evaluate the risk of charged particles. Especially it is important to detect radiation damage induced by the precise number of heavy ions in the individual cells. Thus we studied the relationship between the number of ions traversing the cell and DNA damage produced by the ion irradiation. We applied comet assay to measure the DNA damage in the individual cells. Cells attached on the ion track detector CR-39 were irradiated with ion beams at TIARA, JAERI-Takasaki. After irradiation, the cells were stained with ethidium bromide and the opposite side of the CR-39 was etched. We observed that the heavy ions with higher LET values induced the heavier DNA damage. The result indicated that the amount of DNA damage induced by one particle increased with the LET values of the heavy ions.

Wada, S.; Natsuhori, M.; Ito, N.; Funayama, T.; Kobayashi, Y.

2003-05-01

172

Comparisons of radiation damage in He ion and proton irradiated immiscible Ag/Ni nanolayers  

NASA Astrophysics Data System (ADS)

We compare the evolution of microstructure and mechanical properties of Ag/Ni multilayers of varying layer thickness (1-200 nm) subjected to helium ion and proton irradiation at room temperature to similar dose, ˜2 displacements-per-atom on average. Layer structure remained intact after both types of irradiation although defects accumulated in the layers are different. Helium bubbles were the major defects in helium ion irradiated films, while dislocation loops were ubiquitous in proton irradiated multilayers. In He ion irradiated multilayers, radiation hardening was greater than that in proton irradiated specimens, and the magnitude of hardening decreased with decreasing individual layer thickness. In comparison no size dependent hardening was observed in proton irradiated films. Mechanisms of irradiation induced hardening were discussed.

Yu, K. Y.; Liu, Y.; Fu, E. G.; Wang, Y. Q.; Myers, M. T.; Wang, H.; Shao, L.; Zhang, X.

2013-09-01

173

Amino Acids from Ion-Irradiated Nitrile-Containing Ices  

NASA Astrophysics Data System (ADS)

Solid CH3CN and solid H2O + CH3CN were ion irradiated near 10 K to initiate chemical reactions thought to occur in extraterrestrial ices. The infrared spectra of these samples after irradiation revealed the synthesis of new molecules. After the irradiated ices were warmed to remove volatiles, the resulting residual material was extracted and analyzed. Both unhydrolyzed and acid-hydrolyzed residues were examined by both liquid and gas chromatographic-mass spectral methods and found to contain a rich mixture of products. The unhydrolyzed samples showed HCN, NH3, acetaldehyde (formed by reaction with background and atmospheric H2O), alkyamines, and numerous other compounds, but no amino acids. However, reaction products in hydrolyzed residues contained a suite of amino acids that included some found in carbonaceous chondrite meteorites. Equal amounts of D- and L-enantiomers were found for each chiral amino acid detected. Extensive use was made of 13C-labeled CH3CN to confirm amino acid identifications and discriminate against possible terrestrial contaminants. The results reported here show that ices exposed to cosmic rays can yield products that, after hydrolysis, form a set of primary amino acids equal in richness to those made by other methods, such as photochemistry.

Hudson, Reggie L.; Moore, Marla H.; Dworkin, Jason P.; Martin, Mildred P.; Pozun, Zachary D.

2008-08-01

174

by swift heavy ion irradiation: anomalous photorefractive damage behavior  

NASA Astrophysics Data System (ADS)

Using swift heavy fluorine ion irradiation, we have successfully fabricated optical waveguides in Mg-doped LiNbO3 substrates. A systematic characterization of these structures has been carried out including refractive index profiles, propagation losses, nonlinear coefficients, and, specially, photorefractive optical damage. Step-like refractive index profiles with ?n e ? 0.1 and ?n o ? 0.2, propagation losses lower than 0.5 dB/cm and high nonlinear optical coefficients similar to those of the substrate have been obtained. Unexpectedly, the photorefractive damage is only moderately reduced with regard to the one presented in congruent LiNbO3 waveguides. Specifically, light intensity damage thresholds I th are only a factor 2 higher at RT and a factor 4 at 90 °C with regard to undoped waveguides. At this latter temperature, a remarkably high I th = 30.000 W/cm2 is reached. A final discussion on the observed anomalous optical damage behavior induced by swift heavy ion irradiation is also included.

Jubera, M.; Garcia-Cabañes, A.; Carrascosa, M.; Olivares, J.

2014-08-01

175

Vibrational spectra and structures of bare and Xe-tagged cationic Si(n)O(m)? clusters.  

PubMed

Vibrational spectra of Xe-tagged cationic silicon oxide clusters Si(n)O(m)(+) with n = 3-5 and m = n, n ± 1 in the gas phase are obtained by resonant infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory calculations. The Si(n)O(m)(+) clusters are produced in a laser vaporization ion source and Xe complexes are formed after thermalization to 100 K. The clusters are subsequently irradiated with tunable light from an IR free electron laser and changes in the mass distribution yield size-specific IR spectra. The measured IRMPD spectra are compared to calculated linear IR absorption spectra leading to structural assignments. For several clusters, Xe complexation alters the energetic order of the Si(n)O(m)(+) isomers. Common structural motifs include the Si2O2 rhombus, the Si3O2 pentagon, and the Si3O3 hexagon. PMID:25217922

Savoca, Marco; Langer, Judith; Harding, Dan J; Palagin, Dennis; Reuter, Karsten; Dopfer, Otto; Fielicke, André

2014-09-14

176

Application of heavy-ion microbeam system at Kyoto University: Energy response for imaging plate by single ion irradiation  

NASA Astrophysics Data System (ADS)

A heavy-ion microbeam system for cell irradiation has been developed using an accelerator at Kyoto University. We have successfully developed proton-, carbon-, fluorine- and silicon-beams in order to irradiate a micro-meter sized area with ion counting, especially single ion irradiation. In the heavy-ion microbeam system, an imaging plate (IP) was utilized for beam diagnostics on the irradiation. The IP is widely used for radiography studies in biology. However, there are a few studies on the low linear energy transfer (LET) by single ions, i.e., low-intensity exposure. Thus we have investigated the energy response for the IP, which can be utilized for microbeam diagnostics.

Tosaki, M.; Nakamura, M.; Hirose, M.; Matsumoto, H.

2011-12-01

177

Propagation of ripple patterns on Si during ion bombardment  

NASA Astrophysics Data System (ADS)

The lateral propagation of surface ripples on Si, generated by Xe ion irradiation with and without codeposition of Fe surfactant atoms, was investigated by scanning electron microscopy with the help of micron-sized marker structures prepared by focused ion beam milling. For 10-keV Xe ion irradiation of Si at oblique incidence between 62 and 70°, we determine lateral ripple propagation velocities varying from -1.9 to +2.9 nm per 1015 Xe ions/cm2. The propagation direction changes from opposite to the projected direction of the incident ion beam to along the projected beam direction within a narrow angular regime. At 67°, the pattern is almost static. The result is in good agreement with predictions from the theoretical model of Bradley and Harper. For perpendicular incident 5-keV Xe ions and oblique codeposition of Fe surfactant atoms, we find that ripple patterns propagate across the surface with a negative ripple propagation velocity of about -0.7 nm per 1015 Xe ions/cm2, i.e., opposite to the projected deposition direction of Fe surfactant atoms. The novel experimental method to determine the lateral ripple propagation based on markers set with a focused ion beam system does not require an in situ analysis and can therefore be applied in general to analyze the dynamics of ion beam-induced patterns.

Hofsäss, H.; Zhang, K.; Gehrke, H. G.; Brüsewitz, C.

2013-08-01

178

The role of polarization of Xe by di- and monovalent cations in 129Xe NMR studies in zeolite A.  

PubMed

We consider the role of polarization in the adsorption of Xe in zeolites of type A by direct comparative analysis of the adsorption isotherms, distributions of occupancies, and 129Xe NMR chemical shifts of Xe(n) in cages containing CaxNa12-2x ions per alpha cage (x = 0, 1, 2, 3, 5). We find that the qualitative trends in the adsorption isotherms, and in the progressions of Xe(n) chemical shifts (for n = 0-8 in cages with x = 0, 1 Ca2+ ions and for n = 0-5 in cages with x = 2, 3 Ca2+ ions) upon increasing the level of Ca2+ ion for Na+ ion substitution could only be accounted for by including polarization of the Xe atom by the zeolite framework and its ions. This system, which permits observation of individual Xe(n) peaks and of directly comparable adsorption isotherms in several cage types, provides a good model system for the interpretation of the more general case in which only the overall average 129Xe NMR chemical shift is observed in open network zeolites, arising from free exchange of Xe among cavities of variable occupancy and variable cation distribution. PMID:9477456

Jameson, C J; Lim, H M; Jameson, A K

1997-12-01

179

Calculation of production and decay of radioisotopes for future irradiation experiments and ion beam facilities  

NASA Astrophysics Data System (ADS)

The design of future radioactive ion beam (RIB) facilites requires the forecast of radio isotope inventory after irradiation. At CERN ISOLDE, we developed a software that estimates the activity of irradiated materials as a function of time dedicated to radioactive waste management. This tool can also be used for licensing procedures, planning of irradiation experiments and the estimation of yields.

Eller, M.; Miksch, S.; Lettry, J.; Stora, T.; Catherall, R.

2007-11-01

180

keV Ag ion irradiation induced damage on multiwalled carbon nanotubes  

Microsoft Academic Search

The stability of carbon nanotubes (CNTs) under ion irradiation is an important parameter for the performance of CNT devices under extreme conditions of heat, radiation, etc. In order to investigate the stability and the evolution of nature of bonding, multiwalled carbon nanotubes were irradiated using 21 keV Ag- ions with fluences of 1 × 1013, 5 × 1013, 7 ×

S. Mathew; U. M. Bhatta; B. Joseph; B. N. Dev

2007-01-01

181

Surface pattern formation during MeV energy ion beam irradiation  

SciTech Connect

Surface patterning during high energy heavy ion irradiation is a relatively recent observation. We report in this paper the results of a study on the formation of self organized ripple patterns on silica surface irradiated with MeV energy gold ions.

Srivastava, S. K.; Nair, K. G. M.; Kannan, R. Kamala; Kamruddin, M.; Panigrahi, B. K.; Tyagi, A. K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

2012-06-05

182

Aligned Gold Nanorods in Silica Made by Ion Irradiation of CoreShell  

E-print Network

Aligned Gold Nanorods in Silica Made by Ion Irradiation of Core±Shell Colloidal Particles shows a transmission electron microscopy (TEM) image of a Au±silica core±shell particle before matrix that does deform under the ion beam. To do so, we have irradiated colloidal core±shell particles

Polman, Albert

183

MeV N+-ion irradiation effects on ?-MoO3 thin films  

NASA Astrophysics Data System (ADS)

In this work, modifications in the structural, vibrational, optical, and surface morphological properties of 2MeV N+-ion irradiated ?-MoO3 thin films are studied. Nitrogen irradiation up to the fluence of 1×1015ions cm-2 does not lead to any structural phase change. The irradiation induced formation of nanoscale defect structures at the film surface becomes more prominent at higher irradiation fluences, leading to the enhancement in the optical absorption behavior of the irradiated films. The possible role of energy loss process in the mechanism of modifying the surface morphology has been discussed.

Sivakumar, R.; Sanjeeviraja, C.; Jayachandran, M.; Gopalakrishnan, R.; Sarangi, S. N.; Paramanik, D.; Som, T.

2007-02-01

184

Investigation of Damage with Cluster Ion Beam Irradiation Using HR-RBS  

SciTech Connect

Cluster ion beam can process targets with shallow damage because of the very low irradiation energy per atom. However, it is needed to investigate the damage with cluster ion beam irradiation, because recent applications demand process targets with ultra low damage. The shallow damage can be investigated from depth profiles of specific species before and after ion irradiation. They can be measured with secondary ion mass spectrometry (SIMS) and Rutherford backscattering spectroscopy (RBS). High resolution Rutherford backscattering spectroscopy (HR-RBS) is a non destructive measurement method and depth profiles can be measured with nano-resolution. The cluster ion beam mixing of thin Ni layer in carbon targets can be investigated with HR-RBS. The mixing depth with cluster ion irradiation at 10 keV was about 10 nm. The mixing depth with cluster ion irradiation at 1 keV and 5 keV were less than 1 nm and 5 nm, respectively. The number of displaced Ni atoms with cluster ion irradiation was very larger than that with monomer ion irradiation of same energy. This result shows that violent mixing occurs with single cluster impact.

Seki, Toshio [Department of Nuclear Engineering, Kyoto Univ., Gokasyo, Uji, Kyoto, 611-0011. Japan (Japan); Aoki, Takaaki [Department of Electronic Science and Engineering, Kyoto Univ., Nishikyo-ku, Kyoto, 615-8510 (Japan); Matsuo, Jiro [Quantum Science and Engineering Center, Kyoto Univ., Gokasyo, Uji, Kyoto, 611-0011 (Japan)

2008-11-03

185

Energetic Ion and Electron Irradiation of the Icy Galilean Satellites  

NASA Technical Reports Server (NTRS)

Galileo Orbiter measurements of energetic ions (20 keV to 100 MeV) and electrons (20-700 keV) in Jupiter's magnetosphere are used, in conjunction with the JPL electron model (less than 40 MeV), to compute irradiation effects in the surface layers of Europa, Ganymede, and Callisto. Significant elemental modifications are produced on unshielded surfaces to approximately centimeter depths in times of less than or equal to 10(exp 6) years, whereas micrometer depths on Europa are fully processed in approximately 10 years. Most observations of surface composition are limited to optical depths of approximately 1 mm, which are indirect contact with the space environment. Incident flux modeling includes Stormer deflection by the Ganymede dipole magnetic field, likely variable over that satellite's irradiation history. Delivered energy flux of approximately 8 x 10(exp 10) keV/square cm-s at Europa is comparable to total internal heat flux in the same units from tidal and radiogenic sources, while exceeding that for solar UV energies (greater than 6 eV) relevant to ice chemistry. Particle energy fluxes to Ganymede's equator and Callisto are similar at approximately 2-3 x 10(exp 8) keV/square cm-s with 5 x 10(exp 9) at Ganymede's polar cap, the latter being comparable to radiogenic energy input. Rates of change in optical reflectance and molecular composition on Europa, and on Ganymede's polar cap, are strongly driven by energy from irradiation, even in relatively young regions. Irradiation of nonice materials can produce SO2 and CO2, detected on Callisto and Europa, and simple to complex hydrocarbons. Iogenic neutral atoms and meteoroids deliver negligible energy approximately 10(exp 4-5) keV/square cm-s but impacts of the latter are important for burial or removal of irradiation products. Downward transport of radiation produced oxidants and hydrocarbons could deliver significant chemical energy into the satellite interiors for astrobiological evolution in putative sub-surface oceans.

Cooper, John F.; Johnson, Robert E.; Mauk, Barry H.; Garrett, Henry B.; Gehrels, Neil

2001-01-01

186

Athermal crystallization induced by electronic excitations in ion-irradiated silicon carbide  

SciTech Connect

Silicon carbide single crystals were irradiated at room temperature with low energy I ions and high energy Pb ions. It is found that the damaged layer formed by the elastic collisions generated during low energy I ion irradiation can readily be removed by the electronic excitations induced by swift Pb ions. This effect occurs at a temperature quite below that at which the conventional ion-beam induced crystallization process is generally achieved by nuclear energy loss. This finding is interesting both from a fundamental point of view for the understanding of the interaction of swift heavy ions with solids and for a large number of technological applications.

Benyagoub, A.; Audren, A.; Thome, L.; Garrido, F. [Centre Interdisciplinaire de Recherche Ions Lasers (CIRIL-GANIL), CEA-CNRS-ENSICAEN, BP 5133, Bd Henri Becquerel, F-14070 Caen Cedex 5 (France); Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), CNRS-IN2P3-Universite Paris-Sud, F-91405 Orsay-Campus (France)

2006-12-11

187

Effect of 120 MeV Ag9+ ion irradiation of YCOB single crystals  

NASA Astrophysics Data System (ADS)

Single crystals of yttrium calcium oxy borate (YCOB) grown from boron-tri-oxide flux were subjected to swift heavy ion irradiation using silver Ag9+ ions from the 15 UD Pelletron facility at Inter University Accelerator Center, New Delhi. The crystals were irradiated at 1 × 1013, 5 × 1013 and 1 × 1014 ions/cm2 fluences at room temperature and with 5 × 1013 ions/cm2 fluence at liquid nitrogen temperature. The pristine and the irradiated samples were characterized by glancing angle X-ray diffraction, UV-Vis-NIR and photoluminescence studies. From the characterization studies performed on the samples, it is inferred that the crystals irradiated at liquid nitrogen temperature had fewer defects compared to the crystals irradiated at room temperature and the defects increased when the ion fluence was increased at room temperature.

Arun Kumar, R.; Dhanasekaran, R.

2012-09-01

188

Simulations of Xe and U diffusion in UO2  

SciTech Connect

Diffusion of xenon (Xe) and uranium (U) in UO{sub 2} is controlled by vacancy mechanisms and under irradiation the formation of mobile vacancy clusters is important. Based on the vacancy and cluster diffusion mechanisms established from density functional theory (DFT) calculations, we derive continuum thermodynamic and diffusion models for Xe and U in UO{sub 2}. In order to capture the effects of irradiation, vacancies (Va) are explicitly coupled to the Xe and U dynamics. Segregation of defects to grain boundaries in UO{sub 2} is described by combining the bulk diffusion model with models of the interaction between Xe atoms and vacancies with grain boundaries, which were derived from atomistic calculations. The diffusion and segregation models were implemented in the MOOSE-Bison-Marmot (MBM) finite element (FEM) framework and the Xe/U redistribution was simulated for a few simple microstructures.

Andersson, Anders D. [Los Alamos National Laboratory; Vyas, Shyam [Los Alamos National Laboratory; Tonks, Michael R. [Idaho National Laboratory; Casillas, Luis [Los Alamos National Laboratory; Uberuaga, Blas P. [Los Alamos National Laboratory; Millett, Paul [Idaho National Laboratory

2012-09-10

189

Sympathetic ophthalmia complicating helium ion irradiation of a choroidal melanoma  

SciTech Connect

Sympathetic ophthalmia was diagnosed 49 months after helium ion irradiation of a left choroidal melanoma. The patient maintained good vision until 18 months after therapy, when she developed neovascular glaucoma. This complication required multiple therapeutic procedures, including topical anti-inflammatory and antiglaucomatous drops, 360 degrees peripheral panretinal cryoblation, and a single 180 degrees application of inferior cyclocryotherapy over a 2 1/2-year period. Four weeks after the cyclocryotherapy, inflammation was noted in both eyes, and, one month later, enucleation of the left sympathogenic eye was performed. Serial histopathologic sections showed a full-thickness, fibrovascular, scleral scar and tantalum marker ring suture without uveal incarceration. Penetrating surgical trauma, a uveal melanoma, and multiple nonpenetrating treatments resulted in the development of sympathetic ophthalmia.

Fries, P.D.; Char, D.H.; Crawford, J.B.; Waterhouse, W.

1987-11-01

190

Ion-irradiation studies of cascade damage in metals  

SciTech Connect

Ion-irradiation studies of the fundamental aspects of cascade damage in metals are reviewed. The emphasis of these studies has been the determination of the primary state of damage (i.e. the arrangement of atoms in the cascade region prior to thermal migration of defects). Progress has been made towards understanding the damage function (i.e. the number of Frenkel pairs produced as a function of primary recoil atom energy), the spatial configuration of vacancies and interstitials in the cascade and the cascade-induced mixing of atoms. It is concluded for these studies that the agitation of the lattice in the vicinity of energetic displacement cascades stimulates the defect motion and that such thermal spike motion induces recombination and clustering of Frenkel defects. 9 figures.

Averback, R.S.

1982-03-01

191

Damage in crystalline silicon by swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

We have studied damage of crystalline Si surfaces induced by electronic energy loss of swift heavy ions with an electronic stopping power of up to Se = 12 keV/nm. Scanning tunneling microscope images of the surface after irradiation under perpendicular as well as glancing angles of incidence showed no surface damage. We have performed theoretical calculations for the damage threshold within the two temperature model, resulting in Seth = 8 keV/nm as the minimum stopping power to create a molten zone. We investigate the respective influence of the electron-phonon coupling, of the criterion at which the damage occurs and a possible effect of ballistic electrons. We show that the latter has the strongest effect on the calculated damage threshold.

Osmani, O.; Alzaher, I.; Peters, T.; Ban d'Etat, B.; Cassimi, A.; Lebius, H.; Monnet, I.; Medvedev, N.; Rethfeld, B.; Schleberger, M.

2012-07-01

192

Effects of pulsed dual-ion irradiation of microstructural development  

SciTech Connect

The effect of pulsed irradiation on the development of microstructure during Ni ion bombardment has been investigated in a simple austenitic alloy similar to type 316 stainless steel. Bombardment conditions were 10 dpa, 940 K, pulsing with equal on/off times of either 0.5 or 60 s, and the addition of 20 appM He/dpa to some specimens either by room temperature preimplantation or by dual-beam coimplantation. Particular care was taken to minimize thermal pulses from beam heating (to <2/sup 0/C). The results show that pulsing has a subtle influence, and the effects on specific cavity parameters are complex. Pulsing produced a small increase in swelling in the helium-free case, but a slight decrease for helium-implanted specimens, and it seems to have counteracted the usual stimulative effects of helium on cavity nucleation.

Packan, N.H.

1981-01-01

193

Morphological change of multiwalled carbon nanotubes through high-energy (MeV) ion irradiation  

Microsoft Academic Search

Multiwalled carbon nanotubes (MWCNTs) were expanded by 2.5 times in diameter through high-energy (MeV) ion irradiation. Pristine MWCNTs were synthesized onto SiO2 substrate by chemical vapor deposition. The 4 MeV Cl2+ ions with a dose of 3×1016 ions\\/cm2 were irradiated on MWCNTs. From high-resolution transmission electron microscopy (HR-TEM) images, the average diameter of the high-energy-ion-irradiated MWCNTs was ~180 nm, while

H. M. Kim; H. S. Kim; S. K. Park; J. Joo; T. J. Lee; C. J. Lee

2005-01-01

194

Heavy ion and X-ray irradiation alter the cytoskeleton and cytomechanics of cortical neurons  

PubMed Central

Heavy ion beams with high linear energy transfer exhibit more beneficial physical and biological performance than conventional X-rays, thus improving the potential of this type of radiotherapy in the treatment of cancer. However, these two radiotherapy modalities both cause inevitable brain injury. The objective of this study was to evaluate the effects of heavy ion and X-ray irradiation on the cytoskeleton and cytomechanical properties of rat cortical neurons, as well as to determine the potential mechanism of neuronal injury after irradiation. Cortical neurons from 30 new-born mice were irradiated with heavy ion beams at a single dose of 2 Gy and X-rays at a single dose of 4 Gy; subsequent evaluation of their effects were carried out at 24 hours after irradiation. An immunofluorescence assay showed that after irradiation with both the heavy ion beam and X-rays, the number of primary neurons was significantly decreased, and there was evidence of apoptosis. Radiation-induced neuronal injury was more apparent after X-irradiation. Under atomic force microscopy, the neuronal membrane appeared rough and neuronal rigidity had increased. These cell changes were more apparent following exposure to X-rays. Our findings indicated that damage caused by heavy ion and X-ray irradiation resulted in the structural distortion and rearrangement of the cytoskeleton, and affected the cytomechanical properties of the cortical neurons. Moreover, this radiation injury to normal neurons was much severer after irradiation with X-rays than after heavy ion beam irradiation. PMID:25206772

Du, Yuting; Zhang, Jie; Zheng, Qian; Li, Mingxin; Liu, Yang; Zhang, Baoping; Liu, Bin; Zhang, Hong; Miao, Guoying

2014-01-01

195

Heavy ion and X-ray irradiation alter the cytoskeleton and cytomechanics of cortical neurons.  

PubMed

Heavy ion beams with high linear energy transfer exhibit more beneficial physical and biological performance than conventional X-rays, thus improving the potential of this type of radiotherapy in the treatment of cancer. However, these two radiotherapy modalities both cause inevitable brain injury. The objective of this study was to evaluate the effects of heavy ion and X-ray irradiation on the cytoskeleton and cytomechanical properties of rat cortical neurons, as well as to determine the potential mechanism of neuronal injury after irradiation. Cortical neurons from 30 new-born mice were irradiated with heavy ion beams at a single dose of 2 Gy and X-rays at a single dose of 4 Gy; subsequent evaluation of their effects were carried out at 24 hours after irradiation. An immunofluorescence assay showed that after irradiation with both the heavy ion beam and X-rays, the number of primary neurons was significantly decreased, and there was evidence of apoptosis. Radiation-induced neuronal injury was more apparent after X-irradiation. Under atomic force microscopy, the neuronal membrane appeared rough and neuronal rigidity had increased. These cell changes were more apparent following exposure to X-rays. Our findings indicated that damage caused by heavy ion and X-ray irradiation resulted in the structural distortion and rearrangement of the cytoskeleton, and affected the cytomechanical properties of the cortical neurons. Moreover, this radiation injury to normal neurons was much severer after irradiation with X-rays than after heavy ion beam irradiation. PMID:25206772

Du, Yuting; Zhang, Jie; Zheng, Qian; Li, Mingxin; Liu, Yang; Zhang, Baoping; Liu, Bin; Zhang, Hong; Miao, Guoying

2014-06-01

196

Oxide dispersion strengthened steel irradiation with helium ions  

NASA Astrophysics Data System (ADS)

Oxide dispersion strengthened (ODS) ferritic steels are investigated as possible structural material for the future generation of high temperature gas cooled nuclear reactors. ODS-steels are considered to replace other high temperature materials for tubing or structural parts. The oxide particles serve for interfacial pinning of moving dislocations. Therefore, the creep resistance is improved. In case of the usage of these materials in reactors, the behavior under irradiation must be further clarified. In this paper the effects induced by 4He 2+ implantation into a ferritic ODS steel are investigated. The fluence ranges from 10 16 to 10 17 cm -2 and the energy from 1 to 2 MeV. The induced swelling is investigated for implantations at room temperature and 470 K. It is derived from the irradiation induced surface displacement, which is measured with an atomic force microscope (AFM). With a displacement damage of 0.6 dpa, a volume increase of 0.65% is observed at room temperature and 0.33% at 470 K. A cross-sectional cut is performed by focused ion beam and investigated by transmission electron microcopy (TEM). The defect density observed on the TEM micrographs agrees well with the computational simulation (TRIM) of the damage profile.

Pouchon, M. A.; Chen, J.; Döbeli, M.; Hoffelner, W.

2006-06-01

197

Ion Irradiation Damage in Zirconate and Titanate Ceramics for Pu Disposition  

SciTech Connect

In this paper, we discuss the effect of ion irradiation on pyrochlore-rich titanate and defect-fluorite zirconate ceramics designed for plutonium immobilisation. Samples, with Ce as an analogue for Pu, were made via oxide routes and consolidated by cold-pressing and sintering. Ion irradiation damage was carried out with 2 MeV Au2+ ions to a fluence of 5 ions nm-2 in the accelerator facilities within the Environmental Molecular Sciences Laboratory at Pacific Northwest National Laboratory. Irradiated and non-irradiated samples were examined by x-ray diffraction, scanning and transmission electron microscopy, x-ray photoelectron and infra-red spectroscopy, and spectroscopic ellipsometry. Samples underwent accelerated leach testing at pH 1.75 (nitric acid) at 90°C for 28 days. The zirconate samples were more ion-irradiation damage resistant than the titanate samples, showing little change after ion-irradiation whereas the titanate samples formed an amorphous surface layer ~ 500 nm thick. While all samples had high aqueous durability, the titanate leach rate was ~ 5 times that of the zirconate. The ion-irradiation increased the leach rate of the titanate without impurities by ~ 5 times. The difference in the leach rates between irradiated and unirradiated zirconate samples is small. However, the zirconates were less able to incorporate impurities than the titanate ceramics and required higher sintering temperatures, ~ 1500°C compared to 1350°C for the titanates.

Stewart, Martin W.; Begg, Bruce D.; Finnie, K.; Colella, Michael; Li, H.; McLeod, Terry; Smith, Katherine L.; Zhang, Zhaoming; Weber, William J.; Thevuthasan, Suntharampillai

2004-07-01

198

Nano Pattern on n-Si (100) Surface by Ion Irradiation  

SciTech Connect

Nano structuring of silicon surface by low energy ion irradiation is reported. Semi insulating n-Si (100) has been irradiated by 50 keV Ar{sup +} ion beam at an angle of 50 deg. with respect to surface normal. The irradiated sample's surfaces were analyzed by Atomic Force Microscopy. Irradiation caused formation of nano-sized elliptical dots aligned in rows perpendicular to ion beam direction at fluence of 1x10{sup 17} ions/cm{sup 2}. At higher fluences of 3x10{sup 17} ions/cm{sup 2} and 7x10{sup 17} ions/cm{sup 2} self organized ripples were developed on the surface.

Kumar, Tanuj; Khan, S. A.; Singh, U. B.; Verma, S.; Kanjilal, D. [Inter-university Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067 (India)

2011-07-15

199

Formation of TiO{sub 2} nanorods by ion irradiation  

SciTech Connect

Ion beam irradiation is a powerful method to fabricate and tailor the nanostructured surface of materials. Nanorods on the surface of single crystal rutile TiO{sub 2} were formed by N{sup +} ion irradiation. The dependence of nanorod morphology on ion fluence and energy was elaborated. With increasing ion fluence, nanopores grow in one direction perpendicular to the surface and burst finally to form nanorods. The length of nanorods increases with increasing ion energy under same fluence. The development of the nanorod structure is originated from the formation of the nanopores while N{sub 2} bubbles and aggregation of vacancies were responsible for the formation of nanopores and nanorods. Combining C{sup +} ion irradiation and post-irradiation annealing experiments, two qualitative models are proposed to explain the formation mechanism of these nanorods.

Zheng, X. D.; Ren, F., E-mail: fren@whu.edu.cn; Cai, G. X.; Hong, M. Q.; Xiao, X. H.; Wu, W.; Liu, Y. C.; Li, W. Q.; Ying, J. J.; Jiang, C. Z. [School of Physics and Technology, Center for Ion Beam Application and Center for Electron Microscopy, Wuhan University, Wuhan 430072 (China)

2014-05-14

200

Superlattice-like stacking fault array in ion-irradiated GaN  

SciTech Connect

Controlling defects in crystalline solids is of technological importance for realizing desirable materials properties. Irradiation with energetic particles is useful for designing the spatial distribution and concentration of defects in materials. Here, we performed ion irradiation into hexagonal GaN with the wurtzite structure and demonstrated the spontaneous formation of superlattice-like stacking fault arrays. It was found that the modulation period can be controlled by irradiation conditions and post-irradiation heat treatments.

Ishimaru, Dr. Manabu [Osaka University; Usov, Igor Olegovich [ORNL; Zhang, Yanwen [ORNL; Weber, William J [ORNL

2012-01-01

201

Structural modifications of low-energy heavy-ion irradiated germanium  

SciTech Connect

Heavy-ion irradiation of crystalline germanium (c-Ge) results in the formation of a homogeneous amorphous germanium (a-Ge) layer at the surface. This a-Ge layer undergoes structural modification such as a strong volume expansion accompanied by drastic surface blackening with further ion irradiation. In the present paper we investigate the mechanism of this ion-induced structural modification in a-Ge basically for the irradiation with I ions (3 and 9 MeV) at room and low temperature as a function of ion fluence for the ion incidence angles of {Theta}=7 deg. and {Theta}=45 deg. For comparison, Ag- and Au-ion irradiations were performed at room temperature as a function of the ion fluence. At fluences two orders of magnitude above the amorphization threshold, morphological changes were observed for all irradiation conditions used. Over a wide range of ion fluences we demonstrate that the volume expansion is caused by the formation of voids at the surface and in the depth of the projected ion range. At high ion fluences the amorphous layer transforms into a porous structure as established by cross section and plan view electron microscopy investigations. However, the formation depth of the surface and buried voids as well as the shape and the dimension of the final porous structure depend on the ion fluence, ion species, and irradiation temperature and will be discussed in detail. The rate of the volume expansion (i.e., porous layer formation) depends linearly on the value of {epsilon}{sub n}. This clearly demonstrates that the structural changes are determined solely by the nuclear energy deposited within the amorphous phase. In addition, at high ion fluences all perpendicular ion irradiations lead to a formation of a microstructure at the surface, whereas for nonperpendicular ion irradiations a nonsaturating irreversible plastic deformation (ion hammering) without a microstructure formation is observed. For the irradiation with ion energies of several MeV, the effect of plastic deformation shows a linear dependence on the ion fluence. Based on these results, we provide an explanation for the differences in surface morphology observed for different angles of incidence of the ion beam will be discussed in detail.

Steinbach, T.; Wernecke, J.; Wesch, W. [Institut fuer Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany); Kluth, P.; Ridgway, M. C. [Australian National University, Research School of Physics and Engineering, Canberra (Australia)

2011-09-01

202

keV Ag ion irradiation induced damage on multiwalled carbon nanotubes  

Microsoft Academic Search

The stability of carbon nanotubes (CNTs) under ion irradiation is an important parameter for the performance of CNT devices under extreme conditions of heat, radiation, etc. In order to investigate the stability and the evolution of nature of bonding, multiwalled carbon nanotubes were irradiated using 21keV Ag? ions with fluences of 1×1013, 5×1013, 7×1013 and 1×1014ions\\/cm2. The samples were characterized

S. Mathew; U. M. Bhatta; B. Joseph; B. N. Dev

2007-01-01

203

Behaviour of P, Si, Ni impurities and Cr in self ion irradiated Fe-Cr alloys - Comparison to neutron irradiation  

NASA Astrophysics Data System (ADS)

This paper presents an atom probe tomography study of phase transformation and solute segregation in Fe-Cr alloys of low purity under self-ion irradiation. Fe-9%Cr and Fe-12%Cr were irradiated at 100 °C, 300 °C and 420 °C at a dose of 0.5 dpa. Homogeneously distributed clusters enriched in Cr, P, Si and Ni are shown to form at 300 °C and 420 °C but not at 100 °C. Study of the evolution of the segregation intensities of Cr, Si and P in the clusters with temperature under ion irradiation indicates that they form by a radiation induced mechanism. No ?? clusters were observed whatever the irradiation temperature whereas they were observed in the same alloys after neutron irradiation at 300 °C at 0.6 dpa. Comparison of the solute cluster composition after ion irradiation and neutron irradiation, suggests that P atoms could play an important role in the appearance of the solute clusters by stabilizing point defect clusters that could later be enriched in Ni, Si and Cr.

Pareige, C.; Kuksenko, V.; Pareige, P.

2015-01-01

204

Evaluation of irradiation hardening of ion-irradiated V-4Cr-4Ti and V-4Cr-4Ti-0.15Y alloys by nanoindentation techniques  

NASA Astrophysics Data System (ADS)

Irradiation hardening behavior of V-4Cr-4Ti and V-4Cr-4Ti-0.15Y alloys after Cu-ion beam irradiation were investigated with a combination between nanoindentation techniques and finite element method (FEM) analysis. The ion-irradiation experiments were conducted at 473 K with 2.4 MeV Cu2+ ions up to 7.6 dpa. For the unirradiated materials, the increase in nanoindentation hardness with decreasing indentation depth, so-called indentation size effect (ISE), was clearly observed. After irradiation, irradiation hardening in the measured depth was identified. Hardening behavior of bulk-equivalent hardness for V-4Cr-4Ti-0.15Y alloy was similar to that for V-4Cr-4Ti alloy. Y addition has little effect on irradiation hardening at 473 K. Adding the concept of geometrically necessary dislocations (GNDs) to constitutive equation of V-4Cr-4Ti alloy, the ISE was simulated. A constant value of ? = 0.5 was derived as an optimal value to simulate nanoindentation test for ion-irradiated V-4Cr-4Ti alloy. Adding the term of irradiation hardening ??irrad. to constitutive equation with ? = 0.5, FEM analyses for irradiated surface of V-4Cr-4Ti alloy were carried out. The analytic data of FEM analyses based on neutron-irradiation hardening equivalent to 3.0 dpa agreed with the experimental data to 0.76 dpa. The comparison indicates that irradiation hardening by heavy ion-irradiation is larger than that by neutron-irradiation at the same displacement damage level. Possible mechanisms for extra hardening by heavy ion-irradiation are the processes that the injected Cu ions could effectively produce irradiation defects such as interstitials compared with neutrons, and that higher damage rate of ion-irradiation enhanced nucleation of irradiation defects and hence increased the number density of the defects compared with neutron-irradiation.

Miyazawa, Takeshi; Nagasaka, Takuya; Kasada, Ryuta; Hishinuma, Yoshimitsu; Muroga, Takeo; Watanabe, Hideo; Yamamoto, Takuya; Nogami, Shuhei; Hatakeyama, Masahiko

2014-12-01

205

Modifications of the magnetic properties of ferrites by swift heavy ion irradiations  

NASA Astrophysics Data System (ADS)

Single crystal plates of ferrimagnetic yttrium iron garnet (111)-YIG:Si (Y3Fe4.94Si0.06O12) and barium hexaferrite (00.1)-BaM (BaFe12O19) or (00.1)-BaM:Co,Ti (BaFe9.1Co1.4Ti1.5O19) are irradiated with swift heavy ions (3.8 GeV 129Xe or 6.0 GeV 208Pb) in the electronic slowing down regime, above the threshold (?20 keV nm-1) of formation of continuous and homogeneous cylindrical amorphous tracks. The modifications of the magnetic properties are studied by 57Fe Mössbauer spectroscopy and ac magnetic permeability measurements versus ion fluence. In the doped crystals having a planar magnetic anisotropy (YIG:Si and BaM:Co,Ti), the room-temperature Mössbauer spectra show that the magnetization is flipped perpendicularly to the sample plane at a critical amorphous fraction around 30% in both compounds. This corresponds to a 90% drop of the measured in-plane magnetic permeability. No such effect is seen in the undoped BaM samples with the axial [00.1] anisotropy. These data are interpreted by a magnetomechanical effect generated by the stress field induced by the amorphous tracks in the sample plane which flips the magnetization along the track-axis direction when the stress-induced anisotropy constant surpasses the pristine crystal anisotropy constant at the critical amorphous fraction. In the case of YIG:Si single crystal, a track-induced anisotropy field around 0.1 T is deduced from the Mössbauer spectra under a magnetic field applied in the sample (111) plane which rotates the magnetization back to the easy <111> magnetization axis lying near the sample (111) plane in a reversible manner. The magnetic ordering of amorphous YIG:Si below 70 K is also studied by Mössbauer spectroscopy under high magnetic field (5 T). A two-dimensional Bruggeman model used for the calculation of the permeability of the crystal+amorphous track composites yields track-core radii larger by about 40% than the values previously obtained for both compounds by Mössbauer spectroscopy. We think that such discrepancies show that the samples cannot be treated like standard two-phase composites since the undamaged crystal undergoes a variable stress field depending on the damaged fraction.

Costantini, Jean-Marc; Studer, Francis; Peuzin, Jean-Claude

2001-07-01

206

Electronic spectroscopy of I2-Xe complexes in solid Krypton  

NASA Astrophysics Data System (ADS)

In the present work, we have studied ion-pair states of matrix-isolated I2 with vacuum-UV absorption and UV-vis-NIR emission, where the matrix environment is systematically changed by mixing Kr with Xe, from pure Kr to a more polarizable Xe host. Particular emphasis is put on low doping levels of Xe that yield a binary complex I2-Xe, as verified by coherent anti-Stokes Raman scattering (CARS) measurements. Associated with interaction of I2 with Xe we can observe strong new absorption in vacuum-UV, redshifted 2400 cm-1 from the X ? D transition of I2. Observed redshift can be explained by symmetry breaking of ion-pair states within the I2-Xe complex. Systematic Xe doping of Kr matrices shows that at low doping levels, positions of I2 ion-pair emissions are not significantly affected by complexation with Xe, but simultaneous increase of emissions from doubly spin-excited states indicates non-radiative relaxation to valence states. At intermediate doping levels ion-pair emissions shift systematically to red due to change in the average polarizability of the environment. We have conducted spectrally resolved ultrafast pump-probe ion-pair emission studies with pure and Xe doped Kr matrices, in order to reveal the influence of Xe to I2 dynamics in solid Kr. Strikingly, relaxed emission from the ion-pair states shows no indication of complex presence. It further indicates that the complex escapes detection due to a non-radiative relaxation.

Hulkko, Eero; Ahokas, Jussi; Lindgren, Johan; Myllyperkiö, Pasi; Pettersson, Mika

2012-05-01

207

Detection of high-energy heavy ions using piezoelectric lead zirconate titanate  

SciTech Connect

The characteristics of a radiation detector fabricated with stacks of piezoelectric lead zirconate titanate (PZT) elements were studied by irradiating it with a 400 MeV/n xenon (Xe) beam for various beam pulse durations. This detector is referred to as the multilayered detector (MD). To understand the production mechanism behind the output voltage obtained from the MD, measurement of the spatial distribution of the output signals generated in the MD was attempted. It was found that the amplitude observed was dependent on the number of Xe ions per unit time and the amount of ionization loss energy of Xe ions in PZT.

Takechi, Seiji; Morinaga, Shin-ya; Kurozumi, Atsuma [Graduate School of Engineering, Osaka City University, Osaka 558-8585 (Japan); Miyachi, Takashi; Fujii, Masayuki; Hasebe, Nobuyuki [Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Shibata, Hiromi [Graduate School of Engineering, Kyoto University, Kyoto 606-8501 (Japan); Murakami, Takeshi; Uchihori, Yukio [National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Okada, Nagaya [Honda Electronics Co., Ltd., Aichi 441-3193 (Japan)

2009-04-15

208

Area-selective formation of Si nanocrystals by assisted ion-beam irradiation during dual-ion-beam deposition  

SciTech Connect

We investigate the effect of Ar-ion-beam irradiation during the deposition of SiO{sub x} films by dual-ion-beam deposition system. Ion-beam irradiation effectively increases the oxygen content, x, in SiO{sub x} films indicative of the preferential sputtering of Si phase as compared to SiO{sub 2} phase in SiO{sub x} films. We observe the intense photoluminescence from nonirradiated sample after postdeposition annealing at 1100 deg. C indicating the formation of Si nanocrystals as shown by a cross-sectional transmission electron microscope. However, the increased oxygen content in ion-beam-irradiated sample results in small optical volume of small Si nanocrystals not sufficient for yielding appreciable photoluminescence intensity after postdeposition annealing. The property is utilized for achieving the area-selective formation of Si nanocrytals by inserting a shadow mask in assist ion beam during deposition.

Kim, Jae Kwon; Cha, Kyu Man; Kang, Jung Hyun; Kim, Yong; Yi, Jae-Yel; Chung, Tae Hun; Bark, Hong Jun [Department of Physics, Dong-A University, Hadan-2-dong, Sahagu, Pusan 604-714 (Korea, Republic of)

2004-08-30

209

The potential application of ultra-nanocrystalline diamond films for heavy ion irradiation detection  

SciTech Connect

The potential of utilizing the ultra-nanocrystalline (UNCD) films for detecting the Au-ion irradiation was investigated. When the fluence for Au-ion irradiation is lower than the critical value (f{sub c}= 5.0 Multiplication-Sign 10{sup 12} ions/cm{sup 2}) the turn-on field for electron field emission (EFE) process of the UNCD films decreased systematically with the increase in fluence that is correlated with the increase in sp{sup 2}-bonded phase ({pi}{sup *}-band in EELS) due to the Au-ion irradiation. The EFE properties changed irregularly, when the fluence for Au-ion irradiation exceeds this critical value. The transmission electron microscopic microstructural examinations, in conjunction with EELS spectroscopic studies, reveal that the structural change preferentially occurred in the diamond-to-Si interface for the samples experienced over critical fluence of Au-ion irradiation, viz. the crystalline SiC phase was induced in the interfacial region and the thickness of the interface decreased. These observations implied that the UNCD films could be used as irradiation detectors when the fluence for Au-ion irradiation does not exceed such a critical value.

Chen, Huang-Chin [Department of Physics, Tamkang University, Tamsui, New-Taipei, Taiwan 251 (China); Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, 300 (China); Chen, Shih-Show [Department of Physics, Tamkang University, Tamsui, New-Taipei, Taiwan 251 (China); Department of Information Technology and Mobile Communication, Taipei College of Maritime Technology, Tamsui, New-Taipei, Taiwan 251 (China); Wang, Wei-Cheng; Lin, I-Nan; Chang, Ching-Lin [Department of Physics, Tamkang University, Tamsui, New-Taipei, Taiwan 251 (China); Lee, Chi-Young [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan, 300 (China); Guo, Jinghua [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2013-06-15

210

Evidence for interatomic Coulombic decay in Xe K-shell-vacancy decay of XeF2  

NASA Astrophysics Data System (ADS)

Charge production, charge redistribution, and ion fragmentation are explored in the decay of a Xe K-shell vacancy in XeF2. Coincidence measurements of all ionic fragments in XeF2 provide evidence that an interatomic-Coulombic-decay-like (ICD-like) process plays a role in the cascade decay. The signature of the ICD-like process is an enhancement of the total number of electrons ejected as compared to the case of atomic Xe. The results indicate that the F atoms participate in the decay cascade within the first few femtoseconds after core-hole formation and that fragmentation begins during the decay process.

Dunford, R. W.; Southworth, S. H.; Ray, D.; Kanter, E. P.; Krässig, B.; Young, L.; Arms, D. A.; Dufresne, E. M.; Walko, D. A.; Vendrell, O.; Son, S.-K.; Santra, R.

2012-09-01

211

Radiation Tolerance of Nanocrystal-Based Flash Memory Arrays Against Heavy Ion Irradiation  

Microsoft Academic Search

We present new results on heavy-ion irradiation of nanocrystal non-volatile addressable memory arrays. We show that the effects of a single ion hit are negligible on these devices due to the discrete nature of the storage sites. We estimate that, in order to observe an appreciable threshold voltage shift, at least three to four ion hits are needed. Despite several

Andrea Cester; Nicola Wrachien; Alberto Gasperin; Alessandro Paccagnella; Rosario Portoghese; Cosimo Gerardi

2007-01-01

212

Analysis of ion-bombarded and laser-irradiated surfaces of ZnS and Zn via two-photon high-resolution laser-induced fluorescence spectroscopy  

SciTech Connect

Doppler-shifted two-photon laser-induced fluorescence spectroscopy (LFS) has been used to measure the velocity distributions of Zn atoms ejected by Ar/sup +/ ion bombardment from both a Zn surface and a ZnS single crystal. Doppler-shifted spectroscopy in combination with time of flight(TOF), has also been employed to investigate Zn atoms ejected from a ZnS single crystal under irradiation by 308-nm photons (XeCl excimer laser). The absolute Zn sputtering yields from ion-bombarded and laser-irradiated ZnS samples were determined by comparison with LFS measurements of Zn atoms sputtered from pure Zn targets by Ar/sup +/ ions since the absolute sputtering yield is known. For the Zn target the velocity distributions of the ion-induced sputtered Zn atoms were in good agreement with the Sigmund--Thompson distribution based on the known binding energy of 1.35 eV. On the other hand, the velocity distribution of Zn atoms ion sputtered from ZnS showed some deviation from the Sigmund--Thompson distribution and had a lower binding energy, /similar to/0.9 eV. The velocity distributions of the laser-ablated Zn atoms from ZnS were Maxwell--Boltzmann in nature with characteristic temperatures increasing from 2000 to 9000 K at fluences of 20 and 80 mJ/cm/sup 2/, respectively. The absolute sputtering yield (Y) of Zn sputtered from ZnS was found to be Yapprox. =8 atoms/ion for ion sputtering and Yapprox. =10/sup -6/ atoms/photon at a laser fluence of 30 mJ/cm/sup 2/ for laser ablation. High-resolution Doppler-shift techniques have been combined with TOF techniques. This promising combination permits unambiguous detection of prompt and delayed emission of ablated atoms, as well as the observation of possible molecular or cluster fragmentation.

Arlinghaus, H.F.; Calaway, W.F.; Young, C.E.; Pellin, M.J.; Gruen, D.M.; Chase, L.L.

1989-05-01

213

Difference of Irradiation Effects between Ar Cluster Ion and Ar+ for DLC film formation  

SciTech Connect

In order to study the influences of Ar monomer ion (Ar+) on carbon film properties induced by ion beams assisted deposition, Ar cluster ion, Ar+, and their mixed ions (Ar cluster ion and Ar+) irradiated surface during evaporation and deposition of C60. From Near Edge X-ray Absorption Fine Structure (NEXAFS) and Raman spectroscopy measurements, lower sp2 content in carbon films was obtained via Ar cluster ion beam bombardment in comparison with bombardment by Ar+ and mixed ion beams. Furthermore higher hardness and smoothness of surface were demonstrated via Ar cluster ion bombardments. Thus, it was important to irradiate using higher fraction Ar cluster ions in the beam, in order to obtain hard DLC films with flat surface.

Kitagawa, T. [Lab. of Adv. Sci. and Tech. for industry, Himeji Inst. of Tech., Ako-gun, Hyogo (Japan); Nomura Plating Co. Ltd., Nishiyodogawa, Osaka (Japan); Collaborative Research Center for Cluster ion Beam Process Tech. (Japan); Miyauchi, K.; Kanda, K.; Matsui, S.; Toyoda, N. [Lab. of Adv. Sci. and Tech. for industry, Himeji Inst. of Tech., Ako-gun, Hyogo (Japan); Tsubakino, H. [Faculty of Eng., Himeji Inst of Tech., Shosha, Himeji Hyogo (Japan); Matsuo, J. [Ion Beam Eng. Exp. Lab. Kyoto University, Sakyo, Kyoto (Japan); Yamada, I. [Lab. of Adv. Sci. and Tech. for industry, Himeji Inst. of Tech., Ako-gun, Hyogo (Japan); Collaborative Research Center for Cluster ion Beam Process Tech. (Japan)

2003-08-26

214

The JANNUS Saclay facility: A new platform for materials irradiation, implantation and ion beam analysis  

NASA Astrophysics Data System (ADS)

The third accelerator of the multi-ion irradiation platform JANNUS (Joint Accelerators for Nanosciences and NUclear Simulation), a 6SDH-2 Pelletron from National Electrostatic Corporation, Middleton was installed at Saclay in October 2009. The first triple beam irradiation combining Fe, He and H ion beams has been performed in March 2010. In the first part of this paper, we give a technical description of the triple beam facility, its performances and experimental capabilities. Typically, damage dose up to 100 dpa can be reached in 10 h irradiation with heavy ion beams, with or without simultaneous bombardment by protons, helium-4 ions or any other heavy ion beam. In the second part of this paper, we illustrate some IBA results obtained after irradiation and implantation experiments.

Pellegrino, S.; Trocellier, P.; Miro, S.; Serruys, Y.; Bordas, É.; Martin, H.; Chaâbane, N.; Vaubaillon, S.; Gallien, J. P.; Beck, L.

2012-02-01

215

First multicharged ion irradiation results from the CUEBIT facility at Clemson University  

NASA Astrophysics Data System (ADS)

A new electron beam ion trap (EBIT) based ion source and beamline were recently commissioned at Clemson University to produce decelerated beams of multi- to highly-charged ions for surface and materials physics research. This user facility is the first installation of a DREEBIT-designed superconducting trap and ion source (EBIS-SC) in the U.S. and includes custom-designed target preparation and irradiation setups. An overview of the source, beamline, and other facilities as well as results from first measurements on irradiated targets are discussed here. Results include extracted charge state distributions and first data on a series of irradiated metal-oxide-semiconductor (MOS) device targets. For the MOS devices, we show that voltage-dependent capacitance can serve as a record of the electronic component of ion stopping power for an irradiated, encapsulated oxide target.

Shyam, R.; Kulkarni, D. D.; Field, D. A.; Srinadhu, E. S.; Cutshall, D. B.; Harrell, W. R.; Harriss, J. E.; Sosolik, C. E.

2015-01-01

216

Microstructure and thermal desorption of deuterium in heavy-ion-irradiated pure tungsten  

NASA Astrophysics Data System (ADS)

To understand the fundamental processes of deuterium retention and desorption of irradiated plasma facing materials, thermal desorption of deuterium in pure W with and without ion irradiation up to 2 dpa by 2.4 MeV Cu2+ have been investigated. After the ion irradiation at room temperature, high density of small interstitial typed dislocation loops and also nano-voids due to cascade collisions were detected by TEM observation. Thermal desorption of spectra of D showed that fine vacancy clusters are formed even at low fluence and at room temperature irradiation, these defects act as the strong trapping center of deuterium in the temperature range of 660-900 K.

Watanabe, Hideo; Futagami, Naoki; Naitou, Shiori; Yoshida, Naoaki

2014-12-01

217

Multivariate analysis of Ion Beam Induced Luminescence spectra of irradiated silver ion-exchanged silicate glasses.  

PubMed

A multivariate analysis is used for the identification of the spectral features in Ion Beam Induced Luminescence (IBIL) spectra of soda-lime silicate glasses doped with silver by Ag(+)-Na(+) ion exchange. Both Principal Component Analysis and multivariate analysis were used to characterize time-evolving IBIL spectra of Ag-doped glasses, by means of the identification of the number and of the wavelength positions of the main luminescent features and the study of their evolution during irradiation. This method helps to identify the spectral features of the samples spectra, even when partially overlapped or less intense. This analysis procedure does not require additional input such as the number of peaks. PMID:22571943

Valotto, Gabrio; Quaranta, Alberto; Cattaruzza, Elti; Gonella, Francesco; Rampazzo, Giancarlo

2012-09-01

218

In-situ observation and atomic resolution imaging of the ion irradiation induced amorphisation of graphene  

PubMed Central

Ion irradiation has been observed to induce a macroscopic flattening and in-plane shrinkage of graphene sheets without a complete loss of crystallinity. Electron diffraction studies performed during simultaneous in-situ ion irradiation have allowed identification of the fluence at which the graphene sheet loses long-range order. This approach has facilitated complementary ex-situ investigations, allowing the first atomic resolution scanning transmission electron microscopy images of ion-irradiation induced graphene defect structures together with quantitative analysis of defect densities using Raman spectroscopy. PMID:25284688

Pan, C.-T.; Hinks, J. A.; Ramasse, Q. M.; Greaves, G.; Bangert, U.; Donnelly, S. E.; Haigh, S. J.

2014-01-01

219

Xe- and U-tracks in apatite and muscovite near the etching threshold  

NASA Astrophysics Data System (ADS)

Ion irradiation of a wedge-shaped Durango apatite backed by a mica detector allows investigating ion track ranges and etching properties at different points along the tracks. Transmission profiles obtained by irradiation with 2 × 106 cm-2 11.1 MeV/amu 132Xe and 2 × 106 cm-2 11.1 MeV/amu 238U parallel to the apatite c-axis correspond to ranges calculated with SRIM (Xe: 76.3 ?m; U: 81.1 ?m). However, the measured profiles show much greater etchable track-length variations than the calculated longitudinal straggles. The probable cause is that the length deficit exhibits significant variation from track to track. The measured length deficit in muscovite is in agreement with most existing data. In contrast, the length deficit in apatite appears to be close to zero, which is in conflict with all earlier estimates. This probably results from the etching properties of the apatite basal face, which permit surface-assisted sub-threshold etching of track sections in the nuclear stopping regime. These sections are not accessible from the opposite direction, i.e. by etching towards the endpoint of the tracks or in the direction of the ion beam. This conclusion is supported by the fact that linear dislocations are revealed in apatite basal faces and by the observation of imperfect etch pits that are separated from the etched ion track channel by a section that appears unetched under the microscope.

Wauschkuhn, Bastian; Jonckheere, Raymond; Ratschbacher, Lothar

2015-01-01

220

Microstructural evolution in nickel alloy C-276 after Ar-ion irradiation at elevated temperature  

SciTech Connect

In present work, the irradiation damage in nickel-base alloy C-276 irradiated with Ar-ions was studied. Specimens of C-276 alloy were subjected to an irradiation of Ar-ions (with 120 keV) to dose levels of 6 and 10 dpa at 300 and 550 Degree-Sign C, respectively. The size distributions and densities of dislocation loops caused by irradiation were investigated with transmission electron microscopy. Irradiation hardening due to the formation of the loops was calculated using the dispersed barrier-hardening model, showing that irradiation hardening was greatest at 300 Degree-Sign C/6 dpa. The microstructure evolution induced by Ar-ion irradiation (0-10 dpa) in nickel-base alloy C-276 has been studied using a multi-scale modeling code Radieff constructed based on rate theory, and the size of dislocation loops simulated by Radieff was in good agreement with the experiment. - Highlights: Black-Right-Pointing-Pointer High density of dislocation loops appeared after Ar ions irradiation. Black-Right-Pointing-Pointer Irradiation hardening due to the formation of loops was calculated by the DBH model. Black-Right-Pointing-Pointer Size of loops simulated by Radieff was in good agreement with the experiment.

Jin, Shuoxue [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)] [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); He, Xinfu [China Institute of Atomic Energy, Beijing 102413 (China)] [China Institute of Atomic Energy, Beijing 102413 (China); Li, Tiecheng [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)] [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Ma, Shuli; Tang, Rui [Nuclear Power Institute of China, Chengdu 610041 (China)] [Nuclear Power Institute of China, Chengdu 610041 (China); Guo, Liping, E-mail: guolp@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)] [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)

2012-10-15

221

Nano structuring of GaAs(100) surface using low energy ion irradiation  

SciTech Connect

Nanostructuring of semi insulating GaAs (100) has been observed after irradiation of 50 keV Ar{sup +} ion beam in a wide angular range of 0 deg. to 60 deg. with respect to surface normal. Atomic Force Microscopy (AFM) analysis shows the formation of nano dots at smaller angle of irradiation. At higher angle of irradiation, self organized ripples were developed on the surface. The rms roughness estimated from the AFM analysis shows exponential growth with angle of irradiation. In the high frequency regime, PSD analysis suggests that surface morphology of the irradiated samples is governed by the surface diffusion and mass transport dominated processes.

Kumar, Tanuj; Khan, S. A.; Verma, S.; Kanjilal, D. [Inter-university Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067 (India)

2012-06-05

222

Surface patterning of GaAs under irradiation with very heavy polyatomic Au ions  

NASA Astrophysics Data System (ADS)

Self-organization of surface patterns on GaAs under irradiation with heavy polyatomic Au ions has been observed. The patterns depend on the ion mass, and the substrate temperature as well as the incidence angle of the ions. At room temperature, under normal incidence the surface remains flat, whereas above 200 °C nanodroplets of Ga appear after irradiation with monatomic, biatomic as well as triatomic Au ions of kinetic energies in the range of 10-30 keV per atom. In the intermediate temperature range of 100-200 °C meander- and dot-like patterns form, which are not related to Ga excess. Under oblique ion incidence up to 45° from the surface normal, at room temperature the surface remains flat for mon- and polyatomic Au ions. For bi- and triatomic ions in the range of 60° ? ? ? 70° ripple patterns have been found, which become shingle-like for ? ? 80°, whereas the surface remains flat for monatomic ions.

Bischoff, L.; Böttger, R.; Heinig, K.-H.; Facsko, S.; Pilz, W.

2014-08-01

223

Effect of gigaelectron volt Au-ion irradiation on the characteristics of ultrananocrystalline diamond films  

SciTech Connect

The effect of 2.245 GeV Au-ion irradiation/postannealing processes on the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films was investigated. Au-ion irradiation with a fluence of around 8.4x10{sup 13} ions/cm{sup 2} is required to induce a large improvement in the EFE properties of the UNCD films. Postannealing the Au-ion irradiated films at 1000 deg. C for 1 h slightly degraded the EFE properties of the films but the resulting EFE behavior was still markedly superior to that of pristine UNCD films. Transmission electron microscopy examinations revealed that the EFE properties of the UNCD films are primarily improved by Au-ion irradiation/postannealing processes because of the formation of nanographites along the trajectory of the irradiating ions, which results in an interconnected path for electron transport. In contrast, the induction of grain growth process due to Au-ion irradiation in UNCD films is presumed to insignificantly degrade the EFE properties for the films as the aggregates are scarcely distributed and do not block the electron conducting path.

Chen, Huang-Chin; Teng, Kuang-Yau; Tang, Chen-Yau; Lin, I-Nan [Department of Physics, Tamkang University, Tamsui, Taiwan 251 (China); Sundaravel, Balakrishnan [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Amirthapandian, Sankarakumar [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Institut fuer Halbleiteroptik und Funktionelle Grenzflaechen, Universitaet Stuttgart, Allmandring 3, 70569 Stuttgart (Germany)

2010-12-15

224

Incoherent twin boundary migration induced by ion irradiation in Cu  

SciTech Connect

Grain boundaries can act as sinks for radiation-induced point defects. The sink capability is dependent on the atomic structures and varies with the type of point defects. Using high-resolution transmission electron microscopy, we observed that {Sigma}3{l_brace}112{r_brace} incoherent twin boundary (ITB) in Cu films migrates under Cu{sup 3+} ion irradiation. Using atomistic modeling, we found that {Sigma}3{l_brace}112{r_brace} ITB has the preferred sites for adsorbing interstitials and the preferential diffusion channels along the Shockley partial dislocations. Coupling with the high mobility of grain boundary Shockley dislocations within {Sigma}3{l_brace}112{r_brace} ITB, we infer that {Sigma}3{l_brace}112{r_brace} ITB migrates through the collective glide of grain boundary Shockley dislocations, driven by a concurrent reduction in the density of radiation-induced defects, which is demonstrated by the distribution of nearby radiation-induced defects.

Li, N.; Misra, A. [Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Wang, J.; Wang, Y. Q. [Materials Science and Technology Division, MST-8, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Serruys, Y. [CEA, DEN, Service de Recherches de Metallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Nastasi, M. [Nebraska Center for Energy Sciences Research, University of Nebraska, Lincoln, Nebraska 68588 (United States)

2013-01-14

225

Effect of 100MeV oxygen ion irradiation on silicon NPN power transistor  

SciTech Connect

The radiation response of npn Bipolar junction transistor (BJT) has been examined for 100 MeV O{sup 7+} ion. Key electrical properties like Gummel characteristics, dc current gain and capacitance-voltage of 100MeV O{sup 7+} ion irradiated transistor were studied before and after irradiation. The device was decapped and the electrical characterizations were performed at room temperature. Base current is observed to be more sensitive than collector current and gain appears to be degraded with ion fluence, also considerable degradation in C-V characteristics is observed and doping concentration is found to be increased along with the increase in ion fluence.

Kumar, M. Vinay; Krishnakumar, K. S.; Dinesh, C. M.; Krishnaveni, S.; Ramani [Department of studies in Physics, University of Mysore, Mysore (India); Department of Physics, APS College, Bengaluru (India); Department of Physics, DCE, Govt. First Grade College, Mangalore (India); Department of studies in Physics, University of Mysore, Mysore (India); Department of Physics, Bangalore University, Bengaluru (India)

2012-06-05

226

Nano-porosity in GaSb induced by swift heavy ion irradiation  

SciTech Connect

Nano-porous structures form in GaSb after ion irradiation with 185 MeV Au ions. The porous layer formation is governed by the dominant electronic energy loss at this energy regime. The porous layer morphology differs significantly from that previously reported for low-energy, ion-irradiated GaSb. Prior to the onset of porosity, positron annihilation lifetime spectroscopy indicates the formation of small vacancy clusters in single ion impacts, while transmission electron microscopy reveals fragmentation of the GaSb into nanocrystallites embedded in an amorphous matrix. Following this fragmentation process, macroscopic porosity forms, presumably within the amorphous phase.

Kluth, P., E-mail: patrick.kluth@anu.edu.au; Schnohr, C. S.; Giulian, R.; Araujo, L. L.; Lei, W.; Rodriguez, M. D.; Afra, B.; Bierschenk, T.; Ridgway, M. C. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Sullivan, J.; Weed, R. [ARC Centre for Antimatter-Matter Studies, AMPL, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Li, W.; Ewing, R. C. [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109-1005 (United States)

2014-01-13

227

Structural and photoluminescence properties of swift heavy ion irradiated CdS thin films  

Microsoft Academic Search

This paper reports the results on structural and photoluminescence (PL) properties of thermally evaporated CdS thin films subjected to 100MeV Ag+7 ion irradiation. The structure of the pristine and irradiated films was found to be polycrystalline with preferred orientation along the (002) diffraction line of the CdS hexagonal phase. The films retain their crystallinity upon irradiation indicating structural stability against

R. Sathyamoorthy; S. Chandramohan; P. Sudhagar; D. Kanjilal; D. Kabiraj; K. Asokan

2006-01-01

228

95 MeV oxygen ion irradiation effects on N-channel MOSFETs  

NASA Astrophysics Data System (ADS)

The N-channel metal oxide semiconductor field effect transistors (MOSFETs) were exposed to 95 MeV oxygen ions, in the fluence range of 5 x 10(10) to 5 x 10(13) ions/cm(2). The influence of ion irradiation on threshold voltage (V-TH), linear drain current (I-DLin), leakage current (I-L), drain conductance (g(D)), transconductance (g(m)), mobility (mu) and drain saturation current (I-DSat) of MOSFETs was studied systematically for various fluence. The V-TH of the irradiated MOSFET was found to decrease significantly after irradiation. The interface (N-it) and oxide trapped charge (N-ot) were estimated from the subthreshold measurements and were found to increase after irradiation. The densities of oxide-trapped (DeltaN(it)) charge in irradiated MOSFETs were found to he higher than those of the interface trapped charge (DeltaN(ot)). The I-DLin and I-Dsat of MOSFETs were also found to decrease significantly after irradiation. Studies on effects of 95 MeV oxygen ion irradiation on g(m), g(D) and mu show a degradation varying front 70 to 75% after irradiation. The mobility degradation coefficients for N-it(alpha(it)) and N-ot(alpha(it)) were estimated. The results of these studies are presented and discussed.

Prakash, A. P. G.; Ke, S. C.; Siddappa, K.

2003-09-01

229

Double beta decay searches of 134Xe, 126Xe and 124Xe with large scale Xe detectors  

NASA Astrophysics Data System (ADS)

The sensitivity for double beta decay studies of 134Xe and 124Xe is investigated assuming a potential large scale Xe experiment developed for dark matter searches depleted in 136Xe. The opportunity for an observation of the 2??? - decay of 134Xe is explored for various scenarios. A positive observation should be possible for all calculated nuclear matrix elements. The detection of 2? ECEC of 124Xe can be probed in all scenarios covering the theoretical predicted half-life uncertainties and a potential search for 126Xe is discussed. The sensitivity to {{? }+}EC decay of 124Xe is discussed and a positive observation might be possible, while {{? }+}{{? }+} decay still remains unobservable. The performed studies take into account solar pp–neutrino interactions, 85Kr beta decay and remaining 136Xe double beta decay as background components in the depleted detector.

Barros, N.; Thurn, J.; Zuber, K.

2014-11-01

230

Positron annihilation Doppler broadening spectroscopy study on Fe-ion irradiated NHS steel  

NASA Astrophysics Data System (ADS)

In order to study the evolution of irradiation-induced vacancy-type defects at different irradiation fluences and temperatures, a new type of ferritic/martensitic (F/M) steel named NHS (Novel High Silicon) was irradiated by 3.25 MeV Fe-ion at room temperature and 723 K to fluences of 4.3 × 1015 and 1.7 × 1016 ions/cm2. After irradiation, vacancy-type defects were investigated with variable-energy positron beam Doppler broadening spectra. Energetic Fe-ions produced a large number of vacancy-type defects in the NHS steel, but one single main type of vacancy-type defect was observed in both unirradiated and irradiated samples. The concentration of vacancy-type defects decreased with increasing temperature. With the increase of irradiation fluence, the concentration of vacancy-type defects increased in the sample irradiated at RT, whereas for the sample irradiated at 723 K, it decreased. The enhanced recombination between vacancies and excess interstitial Fe atoms from deeper layers, and high diffusion rate of self-interstitial atoms further improved by diffusion via grain boundary and dislocations at high temperature, are thought to be the main reasons for the reversed trend of vacancy-type defects between the samples irradiated at RT and 723 K.

Zhu, Huiping; Wang, Zhiguang; Gao, Xing; Cui, Minghuan; Li, Bingsheng; Sun, Jianrong; Yao, Cunfeng; Wei, Kongfang; Shen, Tielong; Pang, Lilong; Zhu, Yabin; Li, Yuanfei; Wang, Ji; Song, Peng; Zhang, Peng; Cao, Xingzhong

2015-02-01

231

[Ion-beam irradiated ePTFE for the therapy of intracranial aneurysms].  

PubMed

Intracranial aneurysms are frequently treated with either microsurgical clipping or endovascular coiling. However, as so called broad-neck aneurysms are not suitable for these treatment options, a wrapping technique using muslin gauze, muscle piece, ePTFE is applied for such cases. The material for aneurysmal wrapping demands both stable adherence and no reactive inflammatory response such as inert artificial wall. Authors have developed a new improved ePTFE by ion-beam irradiation technique that is biologically inert and able to adhere firmly to surrounding tissue. Based on the last studies, Ar+ ion at an energy of 150 keV with a fluence of 5 x 10(14) ions/cm2 was chosen to irradiate ePTFE. A cell adhesion test and direct implantation of ion-beam irradiated ePTFE as wrapping material to rabbit common carotid arteries (CCA) were examined. It was demonstrated that the surface of ion-beam irradiated ePTFE exhibits remarkably greater adhesion and promotes cell proliferation on the surface more effectively than that of non-irradiated ePTFE. The carotid artery well-wrapped by ion-beam irradiated ePTFE strongly adhered to the mural wall and induced little inflammatory reaction. The results of this investigation indicate that application of this technology would offer the best means for aneurysm wrapping. PMID:15287485

Yotoriyama, Tasuku; Ujiie, Hiroshi; Takahashi, Noriyoshi; Ono, Yoko; Suzuki, Yoshiaki; Iwaki, Masaya; Hori, Tomokatsu

2004-05-01

232

Low-energy D{sup +} and H{sup +} ion irradiation effects on highly oriented pyrolytic graphite  

SciTech Connect

We have investigated the low-energy (100 eV) D{sup +} and H{sup +} ion irradiation effects on the structural and chemical properties of highly oriented pyrolytic graphite (HOPG). Structural disorder due to the ion irradiation was identified by the Raman spectroscopy, the D{sup +} irradiation giving rise to greater structural disorder than the H{sup +} irradiation. Only sp{sup 2} bonding was identified in the X-ray photoemission spectroscopy of the D{sup +}-irradiated HOPG, indicating no change in the surface chemical structure. The H{sup +} irradiation, on the other hand, gave rise to sp{sup 3} bonding and ???{sup *} transition, the sp{sup 3} bonding increasing with increasing irradiation dose. It is thus shown that the chemical properties of the HOPG surface may be sensitively modified by the low-energy H{sup +} ion irradiation, but not by the low-energy D{sup +} ion irradiation.

Kue Park, Jun; Won Lee, Kyu; Hee Han, Jun; Jung Kweon, Jin; Kim, Dowan; Eui Lee, Cheol [Department of Physics and Institute for Nano Science, Korea University, Seoul 136-713 (Korea, Republic of)] [Department of Physics and Institute for Nano Science, Korea University, Seoul 136-713 (Korea, Republic of); Lim, Sun-Taek; Kim, Gon-Ho [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)] [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Noh, S. J.; Kim, H. S. [Department of Applied Physics, Dankook University, Yongin 448-701 (Korea, Republic of)] [Department of Applied Physics, Dankook University, Yongin 448-701 (Korea, Republic of)

2013-12-07

233

Enhancement of band gap and photoconductivity in gamma indium selenide due to swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

?-In2Se3 thin films prepared at different annealing temperatures ranging from 100to400°C were irradiated using 90MeV Si ions with a fluence of 2×1013ions/cm2. X-ray diffraction analysis proved that there is no considerable variation in structural properties of the films due to the swift heavy ion irradiation. However, photosensitivity and sheet resistance of the samples increased due to irradiation. It was observed that the sample, which had negative photoconductivity, exhibited positive photoconductivity, after irradiation. The negative photoconductivity was due to the combined effect of trapping of photoexcited electrons, at traps 1.42 and 1.26eV, above the valence band along with destruction of the minority carriers, created during illumination, through recombination. Photoluminescence study revealed that the emission was due to the transition to a recombination center, which was 180meV above the valence band. Optical absorption study proved that the defects present at 1.42 and 1.26eV were annealed out by the ion beam irradiation. This allowed photoexcited carriers to reach conduction band, which resulted in positive photoconductivity. Optical absorption study also revealed that the band gap of the material could be increased by ion beam irradiation. The sample prepared at 400°C had a band gap of 2eV and this increased to 2.8eV, after irradiation. The increase in optical band gap was attributed to the annihilation of localized defect bands, near the conduction and valence band edges, on irradiation. Thus, by ion beam irradiation, one could enhance photosensitivity as well as the optical band gap of ?-In2Se3, making the material suitable for applications such as window layer in solar cells.

Sreekumar, R.; Jayakrishnan, R.; Sudha Kartha, C.; Vijayakumar, K. P.; Khan, S. A.; Avasthi, D. K.

2008-01-01

234

Scanning removal of ion-implanted novolak resist by using a laser irradiation  

NASA Astrophysics Data System (ADS)

Novolak resists which are implanted with B, P, and As ions, respectively, were irradiated with a pulsed 532nm laser. Regardless of the implanted ion species and density, more than 74 % of the laser power was found to absorb into the Si wafer surface. For the laser irradiation of 1 pulse, the ion-implanted resist with a density of 5.0x1013 atoms/cm2 was completely stripped in the same way as that of a non-implanted resist. The optical absorption of the resist surface increased as the density of the ion-implantation increased. In case of the ion-implanted resist with a density of 5.0x1015 atoms/cm2, the resist was stripped by 20 pulses irradiation without occurring laser-induced surface damage. A scanning removal of the highly ion-implanted resist was also successfully stripped by using an optimized irradiation condition. A highly ion-implanted resist was continuously stripped by the scanning laser irradiation with 20 pulses.

Kamimura, Tomosumi; Kuroki, Yuta; Kiriyama, Takuya; Muraoka, Hiroki; Nishiyama, Takashi; Harada, Yoshiyuki; Kuramae, Hiroyuki; Horibe, Hideo

2014-09-01

235

Anisotropic dislocation loop nucleation in ion-irradiated MgAl sub 2 O sub 4  

SciTech Connect

Polycrystalline disks of stoichiometric magnesium aluminate spinel (MgAl{sub 2}O{sub 4}) were irradiated with 2 MeV Al{sup +} ions at 650{degrees}C and subsequently analyzed in cross-section using transmission electron microscopy (TEM). Interstitial dislocation loops were observed on 110 and 11 habit planes. The population of loops on both sets of habit planes was strongly dependent on their orientation with respect to the ion beam direction. The density of loops with habit plane normals nearly perpendicular to the ion beam direction much higher than loops with habit plane normals nearly parallel to the ion beam direction. On the other hand, the loop size was nearly independent of habit plane orientation. This anisotropic loop nucleation does not occur in ion-irradiated metals such as copper. An additional anomaly associated with ion-irradiated spinel is that the loops on 111 planes were partially unfaulted with a Burgers vector of b = a/4<110>. Previous neutron irradiation studies have never reported unfaulted loops in stoichiometric spinel. Possible cause of the unusual response of spinel to ion irradiation are discussed. 12 refs., 14 figs.

Zinkle, S.J.

1991-01-01

236

Creation of surface nanostructures in Al2O3 by slow highly charged ions  

NASA Astrophysics Data System (ADS)

Al2O3 single crystals were irradiated with slow highly charged Xe ions of various charge states from an EBIT (Electron Beam Ion Trap) source at the Dresden two source facility. The irradiations were performed at room temperature and under normal incidence. Scanning force microscopy (SFM) was utilized to investigate the topography of the irradiated surfaces. The measurements showed that above a potential energy threshold, each ion creates a nanohillock protruding from the surface. These structures are compared to those created by swift heavy ions (SHI). The results are discussed in terms of potential energy deposition of highly charged ions (HCI) and electronic energy loss of SHI.

El-Said, A. S.; Wilhelm, R. A.; Heller, R.; Akhmadaliev, Sh.; Facsko, S.

2013-12-01

237

Modifying the morphology and magnetic properties of magnetite nanoparticles using swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

Magnetite (Fe3O4) nanospheres of ˜8-11 nm diameter synthesized using a chemical co-precipitation method were deposited as thin films on different substrates using spin coating. The thin films were irradiated with Ag ions at 100 MeV energy. Comparison of unirradiated, as synthesized Fe3O4 nanoparticulate thin film and ion irradiated film shows that irradiation causes dramatic changes in the morphology, structure and magnetic properties. Monte Carlo simulations carried out on this system indicate that the origin of the changes in the magnetic properties lies in the enhanced magnetic anisotropy energy density and reorientation of magnetic easy axis.

Gokhale, Shubha; Lamba, Subhalakshmi; Kumari, Neha; Singh, Bhupendra; Avasthi, D. K.; Kulkarni, S. K.

2014-08-01

238

Characterization of Vacancy Defects in Carbon Ion Irradiated Graphite Using Positrons  

SciTech Connect

Highly Oriented Pyrolytic Graphite samples are irradiated with 200 keV Carbon ions to fluences of 10{sup 14} and 10{sup 15} C{sup +} ions/cm{sup 2}. Depth resolved Doppler lineshape S-parameter exhibited large increase in peak damage regions of the sample, indicating the existence of irradiation induced vacancy defects. The depth profile of the defect region has been deduced from the analysis of the experimental data. It is found that divacancies are the dominant defects in the irradiated samples.

Anto, C. Varghese; Arunkumar, J.; Rajaraman, R.; Nair, K. G. M.; Amarendra, G. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, T.N (India)

2011-07-15

239

I-Xe studies of the Acapulco meteorite: Absolute I-Xe ages of individual phosphate grains and the Bjurböle standard  

Microsoft Academic Search

We have measured Kr and Xe by laser volatilization of seventeen individual neutron-irradiated phosphate grains (nine apatite and eight merrillite) separated from the (reclassified) A-chondrite Acapulco. Radiogenic 129 Xe from now-extinct 129 I is only observed in the apatites, which all formed simultaneously (8.1 ± 1.2 Ma) after Xe closure in the Bjurböle (L4) standard. This relative closure time, when

Robert H. Nichols Jr.; Charles M. Hohenberg; Karl Kehm; Yoosook Kim; Kurt Marti

1994-01-01

240

Influence of irradiation spectrum and implanted ions on the amorphization of ceramics  

SciTech Connect

Polycrystalline Al2O3, magnesium aluminate spinel (MgAl2O4), MgO, Si3N4, and SiC were irradiated with various ions at 200-450 K, and microstructures were examined following irradiation using cross-section TEM. Amorphization was not observed in any of the irradiated oxide ceramics, despsite damage energy densities up to {similar_to}7 keV/atom (70 displacements per atom). On the other hand, SiC readily amorphized after damage levels of {similar_to}0.4 dpa at room temperature (RT). Si3N4 exhibited intermediate behavior; irradiation with Fe{sup 2+} ions at RT produced amorphization in the implanted ion region after damage levels of {similar_to}1 dpa. However, irradiated regions outside the implanted ion region did not amorphize even after damage levels > 5 dpa. The amorphous layer in the Fe-implanted region of Si3N4 did not appear if the specimen was simultaneoulsy irradiated with 1-MeV He{sup +} ions at RT. By comparison with published results, it is concluded that the implantation of certain chemical species has a pronounced effect on the amorphization threshold dose of all five materials. Intense ionizing radiation inhibits amorphization in Si3N4, but does not appear to significantly influence the amorphization of SiC.

Zinkle, S.J.; Snead, L.L.

1995-12-31

241

Swift Heavy Ion Irradiation Effect On Nanometer Range W/Fe Multilayers  

SciTech Connect

The present study reports the effect of swift heavy ion irradiation on structural and magnetic properties of sputtered Fe/W multilayer structure (MLS) having a bilayer composition of [W(30A)/Fe(20A)]{sub 10BL}. The MLS was irradiated by 120 MeV Au{sup 9+} ions up to fluence of 4x10{sup 13} ions/cm{sup 2}. Structural study of pristine and irradiated MLS reveals that intra-layer microstructure of Fe-layers in the MLS becomes nano-crystalline on irradiation. Magnetic studies show increase in coercivity at higher fluence which may be due to increase in surface and interface roughness after recrystallization of Fe-layers.

Bagchi, Sharmistha [UGC-DAE Consortium for Scientific Research, Indore. M.P. INDIA 452001 (India); Institute of Minerals and Materials Technology (IMMT-CSIR) Bhubaneswar Orissa INDIA 751013 (India); Jani, N. P. Lalla Snehal; Lakshmi, N. [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001 (India)

2010-10-04

242

Lattice expansion and microstructure evaluation of Ar ion-irradiated titanium nitride  

NASA Astrophysics Data System (ADS)

Fully dense titanium nitride (TiN) ceramic was irradiated using a 100 keV Ar ion beam at 600 °C and at target fluences of 3 × 1017 ions cm-2, corresponding to 115 displacements per atom (dpa). X-ray diffraction and transmission electron microscopy were performed to evaluate the irradiation damage in the TiN. The lattice parameter increased and the lattice expanded by 0.19% after irradiation due to interstitial atoms and vacancies in Ar-irradiated TiN. Hills, bubbles and dislocations were observed. It is noteworthy that many TiN grains pulled out after irradiation and that amorphization of oxide grain boundaries was observed using high-resolution transmission electron microscopy, which indicates that the oxygen-containing impurities are potentially fatally dangerous to the radiation resistance property of TiN and other candidate materials.

Xue, Jia-Xiang; Zhang, Guo-Jun; Xu, Fang-Fang; Zhang, Hai-Bin; Wang, Xin-Gang; Peng, Shu-Ming; Long, Xing-Gui

2013-08-01

243

Effect of Ar+ ion irradiation on the microstructure of pyrolytic carbon  

NASA Astrophysics Data System (ADS)

Pyrolytic carbon (PyC) coatings prepared by chemical vapor deposition were irradiated by 300 keV Ar+ ions. Then, atomic force microscopy, synchrotron-based grazing incidence X-ray diffraction, Raman spectroscopy, X-ray photoemission spectroscopy, and transmission electron microscopy were employed to study how Ar+ irradiation affects the microstructure of PyC, including the microstructural damage mechanisms and physics driving these phenomena. The 300 keV Ar+ ion irradiation deteriorated the structure along the c-axis, which increased the interlayer spacing between graphene layers. With increasing irradiation dose, the density of defect states on the surface of PyC coating increases, and the basal planes gradually loses their initial ordering resulting in breaks in the lattice and turbulence at the peak damage dose reaches 1.58 displacement per atom (dpa). Surprisingly, the PyC becomes more textured as it becomes richer in structural defects with increasing irradiation dose.

Feng, Shanglei; Yang, Yingguo; Li, Li; Zhang, Dongsheng; Yang, Xinmei; Bai, Shuo; Xia, Huihao; Yan, Long; Huai, Ping; Zhou, Xingtai

2015-03-01

244

Enhancement of impact-induced mechanoluminescence by swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

In this Letter, we report a strategy using swift heavy ion (SHI) irradiation to enhance the impact-induced mechanoluminescence (ML) in ML materials. The impact-induced ML intensity of CaSrAl2Si2O8:Eu2+ was enhanced by about one order of magnitude by using SHI irradiation. Furthermore, the enhancement was found to depend on electronic stopping power and irradiation fluence. The density of traps of a type suitable for impact-induced ML is considered to be increased by the SHI irradiation, resulting in the impact-induced ML enhancement.

Zhan, T. Z.; Xu, C. N.; Yamada, H.; Terasawa, Y.; Zhang, L.; Iwase, H.; Kawai, M.

2012-01-01

245

Hardening of Al-Cu-Mg alloy by energetic ion irradiation  

NASA Astrophysics Data System (ADS)

We irradiated Al-Cu-Mg alloy with 10 MeV iodine ions at room temperature and measured the surface microhardness. We analyzed the microstructure using a three-dimensional atom probe. Irradiation for 3.5 h led to an increase in hardness comparable to that obtained after 4 days of aging at 423 K. Precipitates of about 2.9 nm in diameter were distributed homogeneously over the irradiated region. The nanometer-sized precipitates produced by the irradiation caused a remarkable increase in hardness.

Mitsuda, T.; Kobayashi, I.; Kosugi, S.; Fujita, Nao.; Saitoh, Y.; Hori, F.; Semboshi, S.; Kaneno, Y.; Nishida, K.; Soneda, N.; Iwase, A.

2011-01-01

246

Fragmentation of biomolecules using slow highly charged ions  

SciTech Connect

We present first results of biomolecular fragmentation studies with slow highly charged ions (HCI). A layer of the tripeptide RVA was deposited on gold targets and irradiated with slow (few 100 keV) ions, e.g. Xe{sup 50+} and Xe{sup 15+}, extracted from the LLNL EBIT (electron beam ion trap). The secondary ions released upon ion impact were mass analyzed via Time-Of-Flight Secondary-Ion-Mass-Spectrometry (TOF-SIMS). The results show a strong dependence of the positive and negative ion yields on the charge state of the incident ion. We also found that incident ions with high charge states cause the ejection of fragments with a wide mass range as well as the intact molecule (345 amu). The underlying mechanisms are not yet understood but electron depletion of the target due to the high incident charge is likely to cause a variety of fragmentation processes. 6 refs., 2 figs.

Ruehlicke, C.; Schneider, D.; Balhorn, R. [Lawrence Livermore National Lab., CA (United States); DuBois, R. [Missouri Univ., Rolla, MO (United States). Dept. of Physics

1996-11-01

247

84 MeV C-ions irradiation effects on Zr-45Ti-5Al-3V alloy  

NASA Astrophysics Data System (ADS)

Newly developed Zr-45Ti-5Al-3V alloy were irradiated by 84 MeV carbon ions with doses of 4 * 1015 ions/cm2 and 12 * 1015 ions/cm2, respectively. XRD, SEM, TEM, SAD and tensile tests were performed to study the microstructural evolution and mechanical properties modification upon high energy carbon ion irradiation. XRD patterns show no phase change while the diffraction peak position and intensity vary with irradiation doses. Tensile tests verify monotonic change of alloy strengths and elongations upon irradiation. Microstructure observations of the irradiated samples reveal the irradiation-induced precipitation of (Zr,Ti)3C2, which was believed contributing to the alloy hardening. Superlattice was discovered by the SAD patterns of original and irradiated samples and the high energy C-ions implantation was demonstrated to promote the disorder-order transition by introducing lattice defects.

Wang, Weipeng; Li, Zhengcao; Zhang, Zhengjun; Zhang, Chonghong

2014-09-01

248

Strain-dependent Damage in Mouse Lung After Carbon Ion Irradiation  

SciTech Connect

Purpose: To examine whether inherent factors produce differences in lung morbidity in response to carbon ion (C-ion) irradiation, and to identify the molecules that have a key role in strain-dependent adverse effects in the lung. Methods and Materials: Three strains of female mice (C3H/He Slc, C57BL/6J Jms Slc, and A/J Jms Slc) were locally irradiated in the thorax with either C-ion beams (290 MeV/n, in 6 cm spread-out Bragg peak) or with {sup 137}Cs {gamma}-rays as a reference beam. We performed survival assays and histologic examination of the lung with hematoxylin-eosin and Masson's trichrome staining. In addition, we performed immunohistochemical staining for hyaluronic acid (HA), CD44, and Mac3 and assayed for gene expression. Results: The survival data in mice showed a between-strain variance after C-ion irradiation with 10 Gy. The median survival time of C3H/He was significantly shortened after C-ion irradiation at the higher dose of 12.5 Gy. Histologic examination revealed early-phase hemorrhagic pneumonitis in C3H/He and late-phase focal fibrotic lesions in C57BL/6J after C-ion irradiation with 10 Gy. Pleural effusion was apparent in C57BL/6J and A/J mice, 168 days after C-ion irradiation with 10 Gy. Microarray analysis of irradiated lung tissue in the three mouse strains identified differential expression changes in growth differentiation factor 15 (Gdf15), which regulates macrophage function, and hyaluronan synthase 1 (Has1), which plays a role in HA metabolism. Immunohistochemistry showed that the number of CD44-positive cells, a surrogate marker for HA accumulation, and Mac3-positive cells, a marker for macrophage infiltration in irradiated lung, varied significantly among the three mouse strains during the early phase. Conclusions: This study demonstrated a strain-dependent differential response in mice to C-ion thoracic irradiation. Our findings identified candidate molecules that could be implicated in the between-strain variance to early hemorrhagic pneumonitis after C-ion irradiation.

Moritake, Takashi [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan) [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Proton Medical Research Center, University of Tsukuba, Tsukuba (Japan); Fujita, Hidetoshi; Yanagisawa, Mitsuru; Nakawatari, Miyako; Imadome, Kaori; Nakamura, Etsuko; Iwakawa, Mayumi [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan)] [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Imai, Takashi, E-mail: imait@nirs.go.jp [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan)] [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan)

2012-09-01

249

Sound wave generated by swift heavy ions  

NASA Astrophysics Data System (ADS)

We irradiated samples of polycrystalline metals (Al and Cu) and ceramics (MgO and machinable ceramic) with a short-pulse beam of 3.54-GeV Xe ions and detected sound waves in ultrasonic frequencies with piezoelectric sensors on the surface. On the Al sample, waveforms were observed at different positions relative to the epicenter and were compared with those by 3.8-GeV Ar ion and YAG-laser irradiation. The gross structure of the waveform was similar between the Xe and laser irradiation, where we observed a shear wave which was not found in the Ar-beam irradiation. For the metal samples, the propagation time of the compression wave to the epicenter is shorter for the Xe ion than the laser irradiation. Using the time difference and separately-measured value of speed of sound, we estimated the depth of the sound source in metals and found that it is near the end of the ion range.

Kambara, Tadashi

2006-04-01

250

Argon ion irradiation induced morphological instability of bare and thiol-functionalized Au(111) surfaces.  

PubMed

Ar ion irradiation-induced changes in the morphology of bare and 1-dodecanethiol self-assembled monolayer (SAM) covered Au(111) surfaces have been investigated systematically. The changes were followed by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) measurements while varying the ion charge (Ar(+),Ar(4+)), energy (10-40 keV) and fluency (10(12)-10(13) ions per cm(2)). The impact of flame-annealing of the Au(111) surface on subsequent ion bombardment was considered and more prominent related surface morphology changes were noted. The irradiation of Au(111) surfaces generated Au vacancy and adatom islands and caused roughening of step edges. The size and abundance of these islands and the level of deformation on the step edges depended strongly on the ion energy and fluency. In case of the SAM functionalized surface, the gold vacancy islands present on the surface already from the SAM formation were modified, step edges roughened and gold adatom islands formed. Similarly to the bare surface, the level of surface deformation increased as a function of ion energy and fluency. The Ar(4+) irradiation caused on the average slightly larger vacancy islands on the SAM modified surfaces than the Ar(+) irradiation. Irradiation to fluency of 10(12) ions per cm(2) mostly maintained standing-up orientation of the thiolates whereas irradiation to higher fluency resulted in reduced surface coverage and flat-lying molecules. As a general trend the DDT covered surfaces were more susceptible for irradiation-induced surface morphology changes than the unmodified Au surfaces. PMID:25815628

Venäläinen, Annika; Räisänen, Minna T; Marchand, Benoît; Mizohata, Kenichiro; Räisänen, Jyrki

2015-04-01

251

Etch-free Formation of Porous Silicon by High-energy Ion Irradiation  

SciTech Connect

In this study, porous silicon was fabricated without any chemical etching by self-ion implantation of crystalline Si performed at high temperature and at high fluences. The irradiated silicon samples, which remained crystalline under high temperature ion irradiation, exhibited an increased porous fraction with increasing sample temperature at a given fluence, up to the maximum tested temperature of 650º C. Extremely high ion fluences of at least 2 x 10¹? ions/cm² were necessary to produce significant void growth. Comparisons between the porous silicon structures and irradiation-induced porous networks in Ge, GaSb, and InSb are made, and differences in the formation conditions for these porous networks are discussed.

Perez-Bergquist, Alejandro G.; Naab, Fabian U.; Zhang, Yanwen; Wang, Lumin M.

2011-03-15

252

1\\/f noise studies of swift heavy ion irradiated magnetite thin films  

Microsoft Academic Search

The effect of 190 MeV 107Ag ion irradiation on antiphase boundaries (APBs) of epitaxial Fe3O4 thin films (thickness ˜70 nm) grown on MgO (1 0 0) oriented substrate has been investigated. The X-ray diffraction shows that at low fluence values upto 5 × 1011 ions\\/cm2, the strain in the films is relaxed whereas at high fluence 1 × 1012 ions\\/cm2,

M. Wasi Khan; Ravi Kumar; J. P. Srivastava; S. K. Arora; R. J. Choudhary; I. V. Shvets

2008-01-01

253

Recrystallization of Mn implanted GaAs by He + ion irradiation  

Microsoft Academic Search

Mn ions were implanted into p-GaAs:Zn substrates at room temperature. Post-annealing was performed using 350keV He+ ion irradiation at a temperature of 150–250°C. The structure of the films before and after annealing was characterized by X-ray diffraction. The depth profiles of the implanted Mn+ were measured by secondary ion mass spectrometry. The results indicated that the Mn+ implanted GaAs layer

C. H. Chen; H. Niu; C. Y. Cheng; H. H. Hsieh; S. C. Wu

2008-01-01

254

Recrystallization of Mn implanted GaAs by He+ ion irradiation  

Microsoft Academic Search

Mn ions were implanted into p-GaAs:Zn substrates at room temperature. Post-annealing was performed using 350 keV He+ ion irradiation at a temperature of 150 250 °C. The structure of the films before and after annealing was characterized by X-ray diffraction. The depth profiles of the implanted Mn+ were measured by secondary ion mass spectrometry. The results indicated that the Mn+

C. H. Chen; H. Niu; C. Y. Cheng; H. H. Hsieh; S. C. Wu

2008-01-01

255

New ion beam materials laboratory for materials modification and irradiation effects research  

NASA Astrophysics Data System (ADS)

A new multifunctional ion beam materials laboratory (IBML) has been established at the University of Tennessee, in partnership with Oak Ridge National Laboratory. The IBML is currently equipped with two ion sources, a 3 MV tandem accelerator, three beamlines and three endstations. The IBML is primarily dedicated to fundamental research on ion-solid interaction, ion beam analysis, ion beam modification, and other basic and applied research on irradiation effects in a wide range of materials. An overview of the IBML facility is provided, and experimental results are reported to demonstrate the specific capabilities.

Zhang, Y.; Crespillo, M. L.; Xue, H.; Jin, K.; Chen, C. H.; Fontana, C. L.; Graham, J. T.; Weber, W. J.

2014-11-01

256

STM observation of HOPG surfaces irradiated with Ar cluster ions  

Microsoft Academic Search

Cluster ion beams offer new surface modification processes because of their unique interaction between cluster atoms and solid surfaces. For example, surface smoothing and shallow implantation by cluster ion beam have been demonstrated. In order to reveal such cluster-surface interaction, a single trace formed by a cluster ion impact on a solid surface has been investigated using Scanning Tunneling Microscopy

T. Seki; T. Kaneko; D. Takeuchi; T. Aoki; J. Matsuo; Z. Insepov; I. Yamada

1997-01-01

257

Temperature dependence of ion irradiation induced amorphization of zirconolite  

SciTech Connect

Zirconolite is one of the major host phases for actinides in various wasteforms for immobilizing high level radioactive waste (HLW). Over time, zirconolite's crystalline matrix is damaged by {alpha}-particles and energetic recoil nuclei recoil resulting from {alpha}-decay events. The cumulative damage caused by these particles results in amorphization. Data from natural zirconolites suggest that radiation damage anneals over geologic time and is dependant on the thermal history of the material. Proposed HLW containment strategies rely on both a suitable wasteform and geologic isolation. Depending on the waste loading, depth of burial, and the repository-specific geothermal gradient, burial could result in a wasteform being exposed to temperatures of between 100--450 C. Consequently, it is important to assess the effect of temperature on radiation damage in synthetic zirconolite. Zirconolite containing wasteforms are likely to be hot pressed at or below 1,473 K (1,200 C) and/or sintered at or below 1,623 K (1,350 C). Zirconolite fabricated at temperatures below 1,523 K (1,250 C) contains many stacking faults. As there have been various attempts to link radiation resistance to structure, the authors decided it was also pertinent to assess the role of stacking faults in radiation resistance. In this study, they simulate {alpha}-decay damage in two zirconolite samples by irradiating them with 1.5 MeV Kr{sup +} ions using the High Voltage Electron Microscope-Tandem User Facility (HTUF) at Argonne National Laboratory (ANL) and measure the critical dose for amorphization (D{sub c}) at several temperatures between 20 and 773 K. One of the samples has a high degree of crystallographic perfection, the other contains many stacking faults on the unit cell scale. Previous authors proposed a model for estimating the activation energy of self annealing in zirconolite and for predicting the critical dose for amorphization at any temperature. The authors discuss their results and earlier published data in relation to that model.

Smith, K. L.; Blackford, M. G.; Lumpkin, G. R.; Zaluzec, N. J.

1999-12-22

258

The reaction probability of XeF2 with silicon  

NASA Astrophysics Data System (ADS)

The plasma etching of silicon has been simulated with experiments using atomic fluorine sources or with the dissociative adsorption of XeF2. Atomic fluorine is known to be the species responsible for etching silicon in a plasma, and it is reasonable to question whether XeF2 and atomic fluorine are equivalent reactants with silicon. One means to compare these two reactants is through their reaction probabilities to form SiF4 from a silicon surface. The reaction probability of XeF2 with silicon was measured in the same molecular beam apparatus used to measure the reaction probability of atomic fluorine with silicon. The value for XeF2 is between 1 and 3×10-3 under the conditions employed, and it is a factor of 10 lower than the value obtained for atomic fluorine. Examination of the products obtained from the reaction of XeF2 with silicon shows that there is a range in experimental conditions where the reaction probability is not a unique parameter. The values measured in this experiment represent a lower limit for the reaction probability of XeF2 with silicon. Reactions of XeF2 with silicon are effectively inhibited by a thin surface oxide which must be removed by ion bombardment. No significant differences in reactivity of XeF2 with either single crystal silicon or electron beam evaporated silicon were found.

Vasile, M. J.

1983-11-01

259

Electron capture from H-2 to highly charged Th and Xe ions trapped at center-of-mass energies near 6 eV  

E-print Network

Ions with charge states as high as 80+, produced in the Lawrence Livermore National Laboratory electron beam ion trap were extracted and transferred to a Penning ion trap (RETRAP). RETRAP was operated at cryogenic temperature in the field of a...

Weinberg, G.; Beck, B. R.; Steiger, J.; Church, David A.; McDonald, J.; Schneider, D.

1998-01-01

260

The loss of boron in ultra-shallow boron implanted Si under heavy ion irradiation  

NASA Astrophysics Data System (ADS)

Heavy ion impact has been known to cause a loss of light elements from the near-surface region of the irradiated sample. One of the possible approaches to a better understanding of the processes responsible for the release of specific elements is to irradiate shallow-implanted samples, which exhibit a well-known depth distribution of the implanted species. In this work, the samples studied were produced by implantation of Si wafers with 11 B at implantation energies of 250 and 500 eV and fluence of 1.0x10(15) atoms/cm 2 . Elastic Recoil Detection Analysis was applied to monitor the remnant boron fluence in the sample. Irradiation of the samples by a 14.2 (MeVF4+)-F-19 beam resulted in a slow decrease of boron remnant fluence with initial loss rates of the order of 0.05 B atom per impact ion. Under irradiation with 12 (MeVS3+)-S-32 ions, the remnant boron fluence in Si decreased exponentially with a much faster loss rate of boron and became constant after a certain heavy ion irradiation dose. A simple model, which assumes a finite desorption range and corresponding depletion of the near-surface region, was used to describe the observations. The depletion depths under the given irradiation conditions were calculated from the measured data.

Pelicon, P.; El Bouanani, M.; Prasad, G. V. R.; Razpet, A.; Simcic, J.; Guo, B. N.; Birt, D.; Duggan, J. L.; McDaniel, F. D.

2006-08-01

261

Erosion yield of metal surface under ion pulsed irradiation  

NASA Astrophysics Data System (ADS)

The paper is devoted to the study of erosion processes on a metal surface (Ag, Ni, Cu, W) under argon ion bombardment. The erosion yields including the sputtered and evaporated particles have been calculated for a wide range of the initial ion energy (1-1000 keV). They are revealed to reach the values from units to 104 atom/ion under a pulsed ion beam with the power density of 102-1010 W/cm2. The ion beam and target parameters are shown to influence on the erosion intensity.

Krivobokov, Valery; Stepanova, Olga; Yuryeva, Alena

2013-11-01

262

MeV Au Ion Irradiation in Silicon and Nanocrystalline Zirconia Film Deposited on Silicon Substrate  

SciTech Connect

Nanocrystalline zirconia (ZrO2) film with thickness of 305 nm deposited on a silicon substrate was irradiated with 2 MeV Au ions to different fluences at different temperatures. The implanted ion profiles were measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and simulated using the stopping and range of ions in matter (SRIM) code, respectively. The experimental results show that a large fraction of the incident Au ions penetrates through the ZrO2 film and are deposited into the Si substrate. At the interface of ZrO2 and Si, a sudden decrease of Au concentration is observed due to the much larger scattering cross section of Au in ZrO2 than in Si. The depth profile of the Au ions is measured in both the ZrO2 films and the Si substrates, and the results show that the Au distribution profiles do not exhibit a dependence on irradiation temperature. The local Au concentration increases proportionally with the irradiation fluence, suggesting that no thermal or irradiation-induced redistribution of the implanted Au ions. However, the Au concentration in the ZrO2 films, as determined by SIMS, is considerably lower than that predicted by the SRIM results, and the penetration depth from the SIMS measurements is much deeper than that from the SRIM predictions. These observations can be explained by an overestimation of the electronic stopping power, used in the SRIM program, for heavy incident ions in light targets. Overestimation of the heavy-ion electronic stopping power may lead to errors in local dose calculation and underestimation of the projected range of slow heavy ions in targets that contain light elements. A quick estimate based on a reduced target density may be used to compensate the overestimation of the electronic stopping power in the SRIM program to provide better ion profile prediction.

Chang, Yongqin [University of Science and Technology Beijing, China; Zhang, Yanwen [ORNL; Zhu, Zihua [Pacific Northwest National Laboratory (PNNL); Edmondson, Dr. Philip [University of Oxford; Weber, William J [ORNL

2012-01-01

263

MeV Au Ion Irradiation in Silicon and Nanocrystalline Zirconia Film Deposited on Silicon Substrate  

SciTech Connect

Nanocrystalline zirconia (ZrO2) film with thickness of 305 nm deposited on a silicon substrate was irradiated with 2 MeV Au ions to different fluences at different temperatures. The implanted ion profiles were measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and simulated using the stopping and range of ions inmatter (SRIM) code, respectively. The experimental results show that a large fraction of the incident Au ions penetrates through the ZrO2 film and are deposited into the Si substrate. At the interface of ZrO2 and Si, a sudden decrease of Au concentration is observed due to the much larger scattering cross section of Au in ZrO2 than in Si. The depth profile of the Au ions is measured in both the ZrO2 films and the Si substrates, and the results show that the Au distribution profiles do not exhibit a dependence on irradiation temperature. The local Au concentration increases proportionally with the irradiation fluence, suggesting that no thermal or irradiation-induced redistribution of the implanted Au ions. However, the Au concentration in the ZrO2 films, as determined by SIMS, is considerably lower than that predicted by the SRIM results, and the penetration depth from the SIMS measurements is much deeper than that from the SRIM predictions. These observations can be explained by an overestimation of the electronic stopping power, used in the SRIM program, for heavy incident ions in light targets. Over-estimation of the heavy-ion electronic stopping power may lead to errors in local dose calculation and underestimation of the projected range of slow heavy ions in targets that contain light elements. A quick estimate based on a reduced target density may be used to compensate the overestimation of the electronic stopping power in the SRIM program to provide better ion profile prediction.

Chang, Yongqin; Zhang, Yanwen; Zhu, Zihua; Edmondson, Philip D.; Weber, William J.

2012-09-01

264

Control of cell behavior on PTFE surface using ion beam irradiation  

NASA Astrophysics Data System (ADS)

A polytetrafluoroethylene (PTFE) surface is smooth and biologically inert, so that cells cannot attach to it. Ion beam irradiation of the PTFE surface forms micropores and a melted layer, and the surface is finally covered with a large number of small protrusions. Recently, we found that cells could adhere to this irradiated PTFE surface and spread over the surface. Because of their peculiar attachment behavior, these surfaces can be used as biological tools. However, the factors regulating cell adhesion are still unclear, although some new functional groups formed by irradiation seem to contribute to this adhesion. To control cell behavior on PTFE surfaces, we must determine the effects of the outermost irradiated surface on cell adhesion. In this study, we removed the thin melted surface layer by postirradiation annealing and investigated cell behavior on the surface. On the surface irradiated with 3 × 10 16 ions/cm 2, cells spread only on the remaining parts of the melted layer. From these results, it is clear that the melted layer had a capacity for cell attachment. When the surface covered with protrusions was irradiated with a fluence of 1 × 10 17 ions/cm 2, the distribution of cells changed after the annealing process from 'sheet shaped' into multicellular aggregates with diameters of around 50 ?m. These results indicate that we can control cell behavior on PTFE surfaces covered with protrusions using irradiation and subsequent annealing. Multicellular spheroids can be fabricated for tissue engineering using this surface.

Kitamura, Akane; Kobayashi, Tomohiro; Meguro, Takashi; Suzuki, Akihiro; Terai, Takayuki

2009-05-01

265

Morphological and biochemical responses of Oryza sativa L. (cultivar MR219) to ion beam irradiation*  

PubMed Central

Objective: Heavy ion beam, which has emerged as a new mutagen in the mutation breeding of crops and ornamental plants, is expected to result in the induction of novel mutations. This study investigates the morphological and biochemical responses of Oryza sativa toward different doses of carbon ion beam irradiation. Methods: In this study, the dry seeds of O. sativa were irradiated at 0, 20, 40, 60, 80, 100, and 120 Gy, followed by in-vitro germination under controlled conditions. Morphological and biochemical studies were conducted to investigate the morphological and physiological responses of O. sativa towards ion beam irradiation. Results: The study demonstrated that low doses (10 Gy) of ion beam have a stimulating effect on the height, root length, and fresh weight of the plantlets but not on the number of leaves. Meanwhile, doses higher than 10 Gy caused reductions in all the morphological parameters studied as compared to the control samples. The highest total soluble protein content [(2.11±0.47) mg/g FW] was observed in plantlets irradiated at 20 Gy. All irradiated plantlets were found to have 0.85% to 58.32% higher specific activity of peroxidase as compared to the control samples. The present study also revealed that low doses of ion beam (10 and 20 Gy) had negligible effect on the total chlorophyll content of O. sativa plantlets while 40 Gy had a stimulating effect on the chlorophyll content. Plantlets irradiated between 40 to 120 Gy were shown to be 0.38% to 9.98% higher in total soluble nitrogen content which, however, was not significantly different from the control samples. Conclusions: Carbon ion beam irradiation administered at low to moderate doses of 10 to 40 Gy may induce O. sativa mutants with superior characteristics. PMID:24302713

Ling, Anna Pick Kiong; Ung, Ying Chian; Hussein, Sobri; Harun, Abdul Rahim; Tanaka, Atsushi; Yoshihiro, Hase

2013-01-01

266

Effect of irradiation parameters on defect aggregation during thermal annealing of LiF irradiated with swift ions and electrons  

SciTech Connect

Absorption spectroscopy were performed to study the effects of thermal annealing on the aggregation of color centers in LiF crystals irradiated with different ions between carbon and uranium of megaelectron volt-gigaelectron volt energy. The beam parameters such as energy, energy loss, and fluence have a pronounced influence on the initial defect composition and concentration as well as their evolution upon thermal annealing. A distinct phenomenon was observed, viz., the enhancement of F{sub n} centers for annealing temperatures between 500 and 700 K, followed by Li colloid formation above 700 K. The phenomenon requires specific irradiation conditions whereas the formation of Mg colloids from Mg impurities occurs in all irradiated crystals. The mechanisms of annealing and colloid formation are discussed.

Schwartz, K.; Neumann, R.; Trautmann, C. [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany); Volkov, A. E.; Sorokin, M. V. [Russian Research Center 'Kurchatov Institute', Kurchatov Square 1, 123182 Moscow (Russian Federation)

2010-10-01

267

Recovery and restructuring induced by fission energy ions in high burnup nuclear fuel  

NASA Astrophysics Data System (ADS)

In light water commercial reactors, extensive change of grain structure was found at high burnup ceramic fuels. The mechanism is driven by bombardment of fission energy fragments and studies were conducted by combining accelerator based experiments and computer-science. Specimen of CeO 2 was used as simulation material of fuel ceramics. With swift heavy ion (Xe) irradiation on CeO 2, with 210 MeV, change of valence charge and lattice deviation of cations were observed by XPS and XRD. Combined irradiations of Xe implantation and swift heavy ion irradiation successfully produced sub-micrometer sized sub-grains, similar as that observed in commercial fuels. Studying components of mechanism scenarios, with first principle calculations using the VASP code, we found stable hyper-stoichiometric defect structures of UO 2+x. Molecular dynamics studies revealed stability of Xe planar defects and also found rapid transport mode of oxygen-vacancy clusters.

Kinoshita, M.; Yasunaga, K.; Sonoda, T.; Iwase, A.; Ishikawa, N.; Sataka, M.; Yasuda, K.; Matsumura, S.; Geng, H. Y.; Ichinomiya, T.; Chen, Y.; Kaneta, Y.; Iwasawa, M.; Ohnuma, T.; Nishiura, Y.; Nakamura, J.; Matzke, Hj.

2009-03-01

268

keV ion irradiation assisted prebiotic synthesis of oligopeptide in the solar system  

NASA Astrophysics Data System (ADS)

In this paper, keV ion assisted peptide formation from amino acid monomers is studied. To investigate the possible role of low energy ion irradiation in prebiotic synthesis of oligopeptides, we applied keV Ar + and N + ion beams to solid state phenylalanine. After ion irradiation, it was found that phenylalanine dipeptide was formed and the optimal pH value for peptide formation was 8-9. A radical mechanism was also deduced for our observations. In view of the ubiquitous existence of keV ions in early space and on the early Earth, we suggest that low energy charged particles might have played a role in chemical evolution in the solar system.

Wang, W.; Yuan, H.; Wang, X.; Yu, Z.

269

GaP/Si heteroepitaxy by complex ion beam sputtering  

NASA Astrophysics Data System (ADS)

We have investigated the sputter deposition using a complex ion beam formed with the mixture of Xe and PH3 to grow GaP epitaxial films on Si substrates. The complex ion beam was formed by the cold cathode ion source into which Xe and PH3 gases were fed via variable-leak valves. To reduce the ion beam irradiation damage in the deposited film, the Si substrate was arranged in parallel to the polycrystalline GaP target which was sputtered by the oblique irradiation of the ion beam. The ion beam acceleration voltage was kept at 6.5 kV and the ion beam current density was about 100 ?A/cm2 on the GaP target. The GaP films were deposited at a chamber pressure of 2×10-5 Torr, and the substrate temperature was selected between 400 and 600 °C. The crystalline quality of the deposited GaP films was examined by the reflection high-energy electron diffraction and the surface morphology was observed by the scanning electron microscope. Single-crystalline GaP films were not obtained by the Ar+ or Xe+ ion beam sputter deposition, but were obtained by the complex ion beam sputter deposition using the gas mixture of Xe:PH3 =1:1 as a source gas at a substrate temperature of 500 °C, and also by the PH3 ion beam sputter deposition. The surface morphologies of the GaP films grown by the complex ion beam sputtering were smoother compared with those films deposited by the Ar+ or Xe+ ion beam sputtering.

Ishizuka, F.; Yoshizawa, H.; Itoh, T.

1988-03-01

270

Spontaneous oxidation of xenon to Xe(II) by cationic Ag(II) in anhydrous hydrogen fluoride solutions  

SciTech Connect

Blue solutions, prepared by dissolving AgF{sub 2} in anhydrous hydrogen fluoride (AHF) with BF{sub 3} or AsF{sub 5}, oxidize Xe, at {approximately}20{degree}C, to produce nearly colorless solids. Overall reactions (all in AHF) are as follows: 2AgF{sub 2} + 2BF{sub 3} + Xe {yields} XeF{sub 2} + 2AgBF{sub 4}; 4AgF{sub 2} + 5AsF{sub 5} + 2Xe {yields} Xe{sub 2}F{sub 3}AsF{sub 6} + 4AgAsF{sub 6}. Solid AgF{sub 2} does not interact, at {approximately}20{degree}C, with Xe. Ag(I) in AHF is catalytic to the interaction of Xe with F{sub 2} (Xe + F{sub 2} {yields} XeF{sub 2}), but XeF{sub 2} precipitates AgF{sub 2} from Ag(II) AHF solutions (e.g. AgFAsF{sub 6} + 2XeF{sub 2} {yields} Xe{sub 2}F{sub 3}AsF{sub 6} + AgF{sub 2}). To maintain the Ag(I/II) catalyst the fluoride-ion donor, XeF{sub 2}, must be neutralized with acid, e.g. 2Xe + 2F{sub 2} + AsF{sub 5} {yields} Xe{sub 2}F{sub 3}AsF{sub 6}.

Zemva, B.; Lutar, K.; Jesih, A. (Edvard Kardelj Univ., Ljubljana (Yugoslavia)); Hagiwara, R.; Casteel, W.J. Jr.; Bartlett, N. (Univ. of California, Berkeley (USA))

1990-06-06

271

Degradation of optical properties in Mo mirrors under irradiation with low energy helium and deuterium ions  

NASA Astrophysics Data System (ADS)

Degradation of the optical properties in polycrystalline Mo mirrors irradiated with 1-5 keV helium or deuterium ions has been studied by in situ reflectivity measurement, SEM, TEM and spectroscopic ellipsometry. It has been shown that the reflectivity in these specimens at a wavelength range of (320-850) nm decreases with increase in the fluence and the energy of the ions, and that the degradation in helium irradiated specimens is greater than that in deuterium irradiated specimens. It has been demonstrated that optical constants vary due to formation of a damaged layer in the surface and subsurface region. Particularly in a helium irradiated specimens, the real part of the dielectric constant changes from negative to positive values and its imaginary part considerably decreases due to the bubble formation. These results suggest that penetration of the laser light is facilitated by the formation of damage such as bubbles and results in the degradation of reflectivity.

Nakano, T.; Miyamoto, M.; Hasuike, S.; Ono, K.; Yoshida, N.

2011-10-01

272

Space Plasma Ion Processing of Ilmenite in the Lunar Soil: Insights from In-Situ TEM Ion Irradiation Experiments  

NASA Technical Reports Server (NTRS)

Space weathering on the moon and asteroids results largely from the alteration of the outer surfaces of regolith grains by the combined effects of solar ion irradiation and other processes that include deposition of impact or sputter-derived vapors. Although no longer considered the sole driver of space weathering, solar ion irradiation remains a key part of the space weathering puzzle, and quantitative data on its effects on regolith minerals are still in short supply. For the lunar regolith, previous transmission electron microscope (TEM) studies performed by ourselves and others have uncovered altered rims on ilmenite (FeTiO3) grains that point to this phase as a unique "witness plate" for unraveling nanoscale space weathering processes. Most notably, the radiation processed portions of these ilmenite rims consistently have a crystalline structure, in contrast to radiation damaged rims on regolith silicates that are characteristically amorphous. While this has tended to support informal designation of ilmenite as a "radiation resistant" regolith mineral, there are to date no experimental data that directly and quantitatively compare ilmenite s response to ion radiation relative to lunar silicates. Such data are needed because the radiation processed rims on ilmenite grains, although crystalline, are microstructurally and chemically complex, and exhibit changes linked to the formation of nanophase Fe metal, a key space weathering process. We report here the first ion radiation processing study of ilmenite performed by in-situ means using the Intermediate Voltage Electron Microscope- Tandem Irradiation facility (IVEM-Tandem) at Argonne National Laboratory. The capability of this facility for performing real time TEM observations of samples concurrent with ion irradiation makes it uniquely suited for studying the dose-dependence of amorphization and other changes in irradiated samples.

Christoffersen, R.; Keller, L. P.

2007-01-01

273

Mutation induction in bacteria after heavy ion irradiation  

SciTech Connect

From a compilation of experimental data on the mutagenic effects of heavy ions in bacteria, main conclusions have been drawn as follows: (1) The mutagenic efficacy of heavy ions in bacteria depends on physical and biological variables. Physical variables are the radiation dose, energy and charge of the ion; the biological variables are the bacterial strain, the repair genotype of bacteria, and the endpoint investigated (type of mutation, induction of enzymes related to mutagenesis); (2) The responses on dose or fluence are mainly linear or linear quadratic. The quadratic component, if found for low LET radiation, is gradually reduced with increasing LET; (3) At low values of Z and LET the cross section of mutation induction sigma m (as well as SOS response, sigma sos and lambda phage induction), sigma lambda versus LET curves can be quite consistently described by a common function which increases up to approximately 100 keV/mu m. For higher LET values, the sigma(m) versus LET curves show the so-called `hooks` observed also for other endpoints; (4) For light ions (Z is less than or equal to 4), the cross sections mostly decrease with increasing ion energy, which is probably related to the decrease of the specific energy departed by the ion inside the sensitive volume (cell). For ions in the range of Z = 10, sigma(m) is nearly independent on the ion energy. For heavier ions (Z is greater than or equal to 16), sigma(m) increases with the energy up to a maximum or saturation around 10 MeV/u. The increment becomes steeper with increasing atomic number of the ion. It correlates with the increasing track radius of the heavy ion; (5) The mutagenic efficiency per lethal event changes slightly with ion energy, if Z is small indicating a rough correlation between cellular lethality and mutation induction, only.

Horneck, G.; Kozubek, S. [Ceskoslovenska Akademie Ved, Brno (Czechoslovakia)

1994-12-31

274

The assessment of microscopic charging effects induced by focused electron and ion beam irradiation of dielectrics.  

PubMed

Energetic beams of electrons and ions are widely used to probe the microscopic properties of materials. Irradiation with charged beams in scanning electron microscopes (SEM) and focused ion beam (FIB) systems may result in the trapping of charge at irradiation induced or pre-existing defects within the implanted microvolume of the dielectric material. The significant perturbing influence on dielectric materials of both electron and (Ga(+)) ion beam irradiation is assessed using scanning probe microscopy (SPM) techniques. Kelvin Probe Microscopy (KPM) is an advanced SPM technique in which long-range Coulomb forces between a conductive atomic force probe and the silicon dioxide specimen enable the potential at the specimen surface to be characterized with high spatial resolution. KPM reveals characteristic significant localized potentials in both electron and ion implanted dielectrics. The potentials are observed despite charge mitigation strategies including prior coating of the dielectric specimen with a layer of thin grounded conductive material. Both electron- and ion-induced charging effects are influenced by a delicate balance of a number of different dynamic processes including charge-trapping and secondary electron emission. In the case of ion beam induced charging, the additional influence of ion implantation and nonstoichiometric sputtering from compounds is also important. The presence of a localized potential will result in the electromigration of mobile charged defect species within the irradiated volume of the dielectric specimen. This electromigration may result in local modification of the chemical composition of the irradiated dielectric. The implications of charging induced effects must be considered during the microanalysis and processing of dielectric materials using electron and ion beam techniques. PMID:17279517

Stevens-Kalceff, Marion A; Levick, Katie J

2007-03-01

275

Biodamage via shock waves initiated by irradiation with ions  

PubMed Central

Radiation damage following the ionising radiation of tissue has different scenarios and mechanisms depending on the projectiles or radiation modality. We investigate the radiation damage effects due to shock waves produced by ions. We analyse the strength of the shock wave capable of directly producing DNA strand breaks and, depending on the ion's linear energy transfer, estimate the radius from the ion's path, within which DNA damage by the shock wave mechanism is dominant. At much smaller values of linear energy transfer, the shock waves turn out to be instrumental in propagating reactive species formed close to the ion's path to large distances, successfully competing with diffusion. PMID:23411473

Surdutovich, Eugene; Yakubovich, Alexander V.; Solov'yov, Andrey V.

2013-01-01

276

Microstructure evolution during silicon oxidation at room temperature under composite ion beam irradiation  

NASA Astrophysics Data System (ADS)

In this work, we studied the silicon microstructure evolution during its oxidation under composite beam ion irradiation at room temperature. It was found that when the composite ion beam was formed by hydrogen and dry oxygen mixture at low doses (?1018 cm-2), a porous silicon layer was formed. During irradiation, the pore size gradually reduced and at a dose of ?1020 cm-2 pores disappear completely, and an uniform layer of silicon oxide was formed. If residual gases and hydrogen are used to generate a composite ion beam, the formation of porous silicon is not found. The final thickness of irradiation-induced silicon oxide corresponded to the projected range of protons at a given energy in both cases.

Prikhodko, K. E.; Gurovich, B. A.; Komarov, D. A.; Goncharova, D. A.; Kutuzov, L. V.

2014-05-01

277

Effect of nitrate ions on the oxidation of iodide ions during the dissolution of ?-irradiated NaCl in aqueous binary mixture of iodide and nitrate  

Microsoft Academic Search

It is now well established that the oxidation of iodide ions and the reduction of nitrate ions take place when -irradiated sodium chloride is dissolved in aqueous iodide and nitrate solutions, respectively. The yield of iodine decreases and that of nitrite increases with increasing concentration of nitrate in a binary mixture of iodide and nitrate when the irradiated salt is

C. D. Kalkar; S. V. Doshi

1988-01-01

278

Characterization of biodegradable polymers irradiated with swift heavy ions  

NASA Astrophysics Data System (ADS)

In view of their application as biomaterials, there is an increasing interest in developing new methods to induce controlled cell adhesion onto polymeric materials. The critical step in all these methods involves the modification of polymer surfaces, to induce cell adhesion, without changing theirs degradation and biocompatibility properties. In this work two biodegradable polymers, polyhydroxybutyrate (PHB) and poly- L-lactide acid (PLLA) were irradiated using carbon and sulfur beams with different energies and fluences. Pristine and irradiated samples were degradated by immersion in a phosphate buffer at pH 7.0 and then characterized. The analysis after irradiation and degradation showed a decrease in the contact angle values and changes in their crystallinity properties.

Salguero, N. G.; del Grosso, M. F.; Durán, H.; Peruzzo, P. J.; Amalvy, J. I.; Arbeitman, C. R.; García Bermúdez, G.

2012-02-01

279

The effect of He and swift heavy ions on nanocrystalline zirconium nitride  

NASA Astrophysics Data System (ADS)

Recent studies have shown that swift heavy ion irradiation may significantly modulate hydrogen and helium behaviour in some materials. This phenomenon is of considerable practical interest for ceramics in general and also for candidate materials for use as inert matrix fuel hosts. These materials will accumulate helium via (n, ?) reactions and will also be subjected to irradiation by fission fragments. Cross-sectional transmission electron microscopy and scanning electron microscopy was used to study nanocrystalline ZrN irradiated with 30 keV He to fluences between 1016 and 5 × 1016 cm-2, 167 MeV Xe to fluences between 5 × 1013 and 1014 cm-2 and also 695 MeV Bi to a fluence of 1.5 × 1013 cm-2. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C and were analysed using SEM, XTEM and selected area diffraction. The results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. SEM and XTEM analysis of He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.

Janse van Vuuren, A.; Neethling, J. H.; Skuratov, V. A.; Uglov, V. V.; Petrovich, S.

2014-05-01

280

Ion irradiation induced enhancement of out-of-plane magnetic anisotropy in ultrathin Co films  

SciTech Connect

Ga{sup +} or He{sup +} irradiated MBE grown ultrathin films of sapphire/Pt/Co(d{sub Co})/Pt(d{sub Pt}) were studied using polar Kerr effect in wide ranges of both cobalt d{sub Co} and platinum d{sub Pt} thicknesses as well as ion fluences F. Two branches of increased magnetic anisotropy and enhanced Kerr rotation angle induced by Ga{sup +} or He{sup +} irradiation are clearly visible in two-dimensional (d{sub Co}, LogF) diagrams. Only Ga{sup +} irradiation induces two branches of out-of-plane magnetization state.

Mazalski, P.; Kurant, Z.; Maziewski, A. [Faculty of Physics, University of Bialystok, Bialystok (Poland); Liedke, M. O.; Fassbender, J. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Baczewski, L. T.; Wawro, A. [Institute of Physics, Polish Academy of Science, Warszawa (Poland)

2013-05-07

281

Photoinduced currents in pristine and ion irradiated kapton-H polyimide  

NASA Astrophysics Data System (ADS)

The photoinduced currents in pristine and ion irradiated kapton-H polyimide have been investigated for different applied electric fields at 200°C. Particularly the effect of illumination intensity on the maximum current obtained as a result of photoinduced polarization has been studied. Samples were irradiated by using PELLETRON facility, IUAC, New Delhi. The photo-carrier charge generation depends directly on intensity of illumination. The samples irradiated at higher fluence show a decrease in the peak current with intensity of illumination. The secondary radiation induced crystallinity (SRIC) is responsible for the increase in maximum photoinduced currents generated with intensity of illumination.

Sharma, Anu; Sridharbabu, Y.; Quamara, J. K.

2014-10-01

282

Interaction of deuterium with vacancies induced by ion irradiation in W  

NASA Astrophysics Data System (ADS)

The tritium inventory in plasma-facing materials (PFMs) is an important issue in fusion reactors. Tungsten (W), which is a candidate PFM, has a very low solubility for hydrogen isotopes, but intrinsic and radiation-induced defects can retain a significant amount of hydrogen. A positron annihilation technique was used to investigate the interactions between deuterium (D) and vacancies in W irradiated by Cu ions. The results indicated that vacancies were formed in W after Cu ion irradiation, and that D atoms were trapped by these vacancies.

Xu, Q.; Sato, K.; Cao, X. Z.; Zhang, P.; Wang, B. Y.; Yoshiie, T.; Watanabe, H.; Yoshida, N.

2013-11-01

283

Evaluation of Surface Damage of Organic Films due to Irradiation with Energetic Ion Beams  

SciTech Connect

The surface of L-leucine films irradiated with an Ar{sub 5000} cluster ion beam (5 keV) was characterized by using the X-ray reflective (XRR) measurement method, atomic force microscopy (AFM) and ellipsometry. No significant damage was detected on the surface of the L-leucine films irradiated with the Ar cluster ion beam. Therefore, the large cluster-low-energy (about 1 eV/atom) beam would be suitable for low-damage etching of organic materials.

Hada, Masaki; Hontani, Yusaku; Ichiki, Kazuya; Seki, Toshio [Department of Nuclear Engineering, Kyoto University, Sakyo, Kyoto, 606-8501 (Japan); Ibuki, Sachi; Ninomiya, Satoshi; Matsuo, Jiro [Quantum Science and Engineering Center, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Aoki, Takaaki [Department of Electronic Science and Engineering, Kyoto University, Nishigyo, Kyoto, 615-8530 (Japan)

2011-01-07

284

Depth distribution of displacement damage in. cap alpha. -iron under triple beam ion irradiation  

SciTech Connect

The depth dependence of the defect structures was determined for iron irradiated at 850/sup 0/K with 4 MeV Fe/sup 2 +/ and energetic helium and deuteron ions to 10 dpa and fusion levels of helium and deuterium. From the damage profiles, a sectioning depth of 0.9 ..mu..m was selected for studies of iron and bcc iron alloys, such as ferritic steels, utilizing similar irradiation parameters. A comparison of the experimental damage profile to the deposited energy and deposited ion profiles calculated by E-DEP-1 indicated a possible overestimate of the LSS stopping power of at least 22%.

Horton, L.L.; Bentley, J.; Jesser, W.A.

1981-01-01

285

Hardness enhancement and crosslinking mechanisms in polystyrene irradiated with high energy ion-beams  

SciTech Connect

Surface hardness values several times larger than steel were produced using high energy ion beams at several hundred keV to MeV. High LET is important for crosslinking. Crosslinking is studied by analyzing hardness variations in response to irradiation parameter such as ion species, energy, and fluence. Effective crosslinking radii at hardness saturation are derived base on experimental data for 350 keV H{sup +} and 1 MeV Ar{sup +} irradiation of polystyrene. Saturation value for surface hardness is about 20 GPa.

Lee, E.H.; Rao, G.R.; Mansur, L.K.

1996-12-31

286

Thermal stability of embedded metal nanoparticles elongated by swift heavy ion irradiation: Zn nanoparticles in a molten state but preserving elongated shapes.  

PubMed

Solid Zn and V nanoparticles (NPs) embedded in silica were elongated by swift heavy ion (SHI) irradiation with 200 MeV Xe(14+) ions to a fluence of 5.0 × 10(13) ions cm(-2). Isochronal annealing was carried out in a vacuum from 200 to 1000 °C in steps of 100 °C for 10 min each. The degree of shape elongation was evaluated at room temperature (RT) by two different optical methods: linear dichroism spectroscopy and birefringence spectroscopy. In the as-irradiated state, the samples showed an absorption band at 5 eV due to radiation-induced defects in the silica in addition to the anisotropic absorption due to the elongated metal NPs. After annealing at 400 °C the defect band had completely disappeared, while the degree of shape elongation was almost unchanged or rather slightly increased in both the Zn and V NPs. The elongation of the Zn NPs slightly decreased but maintained a certain value after annealing at 500 °C, which is much higher than the melting point (MP) of Zn NPs (~420 °C). This observation indicates that shape elongation is mostly maintained even if the Zn NPs are in the molten state to some extent during annealing. The elongation of the Zn NPs was almost eliminated after annealing at 600 °C. In the case of the V NPs, elongation was maintained up to 800 °C but mostly eliminated at 900 °C. Since the recovery temperature of 900 °C from the elongated to the spherical shape is much lower than the MP of bulk V (1890 °C), we consider that the elongation is eliminated without melting of V NPs, i.e. via solid state mass transportation. The melting of NPs is not the key factor for the recovery to the spherical shape. PMID:22322542

Amekura, Hiro; Sele, Marta Lill; Ishikawa, Norito; Okubo, Nariaki

2012-03-01

287

75 MeV boron ion irradiation studies on Si PIN photodiodes  

NASA Astrophysics Data System (ADS)

The highly sensitive silicon PIN photodiodes were fabricated to use in radiation environments. The Si PIN photodiodes are coated with 150 nm silicon dioxide (SiO2) as anti-reflective (AR) coating. The presence of AR coating on the performance of irradiated PIN photodiodes is studied up to a total dose of 10 Mrad. The effects of 75 MeV boron (B5+) ions and 60Co gamma radiation on the I-V, C-V and spectral responses of PIN photodiodes were studied systematically to understand the radiation tolerance of the devices. The 75 MeV B5+ irradiation results are compared with 60Co gamma irradiated results in the same dose range for 1 mm × 1 mm and 10 mm × 10 mm active area PIN photodiodes. The irradiation results show that the ion irradiated PIN photodiodes show more degradation when compared 60Co gamma irradiated devices. The irradiation results are presented in this paper and the possible mechanism behind the degradation of photodiodes is also discussed in the paper.

Prabhakara Rao, Y. P.; Praveen, K. C.; Rejeena Rani, Y.; Tripathi, Ambuj; Gnana Prakash, A. P.

2013-12-01

288

Mutation induction in bacteria after heavy ion irradiation  

NASA Technical Reports Server (NTRS)

From a compilation of experimental data on the mutagenic effects of heavy ions in bacteria, main conclusions have been drawn as follows: (1) The mutagenic efficacy of heavy ions in bacteria depends on physical and biological variables. Physical variables are the radiation dose, energy and charge of the ion; the biological variables are the bacterial strain, the repair genotype of bacteria, and the endpoint investigated (type of mutation, induction of enzymes related to mutagenesis); (2) The responses on dose or fluence are mainly linear or linear quadratic. The quadratic component, if found for low LET radiation, is gradually reduced with increasing LET; (3) At low values of Z and LET the cross section of mutation induction sigma m (as well as SOS response, sigma sos. and lambda phage induction, sigma lambda versus LET curves can be quite consistently described by a common function which increases up to approximately 100 keV/mu m. For higher LET values, the sigma(m) versus LET curves show the so-called 'hooks' observed also for other endpoints; (4) For light ions (Z is less than or equal to 4), the cross sections mostly decrease with increasing ion energy, which is probably related to the decrease of the specific energy departed by the ion inside the sensitive volume (cell). For ions in the range of Z = 10, sigma(m) is nearly independent on the ion energy. For heavier ions (Z is greater than or equal to 16), sigma(m) increases with the energy up to a maximum or saturation around 10 MeV/u. The increment becomes steeper with increasing atomic number of the ion. It correlates with the increasing track radius of the heavy ion; (5) The mutagenic efficiency per lethal event changes slightly with ion energy, if Z is small indicating a rough correlation between cellular lethality and mutation induction, only. For ions of higher Z this relation increases with energy, indicating a change in the 'mode' of radiation action from 'killing-prone' to 'mutation-prone'; and (6) Repair genotype substantially influences the radiation induced mutagenesis. Different mechanisms of mutation induction and/or different types of biologically significant lesions in wild type cells compared to repair deficient strains are a likely explanation.

Horneck, G.; Kozubek, S.

1994-01-01

289

Evaluation of surface damage on organic materials irradiated with Ar cluster ion beam  

SciTech Connect

The sputtering yields of organic materials under large cluster ion bombardment are much higher than those under conventional monomer ion bombardment. The sputtering rate of arginine remains constant with fluence for an Ar cluster ion beam, but decreases with fluence for Ar monomer. Additionally, because Ar cluster etching induces little damage, Ar cluster ion can be used to achieve molecular depth profiling of organic materials. In this study, we evaluated the damage to poly methyl methacrylate (PMMA) and arginine samples irradiated with Ar atomic and Ar cluster ion beams. Arginine samples were analyzed by secondary ion mass spectrometry (SIMS) and PMMA samples were analyzed by X-ray photoelectron spectroscopy (XPS). The chemical structure of organic materials remained unchanged after Ar cluster irradiation, but was seriously damaged. These results indicated that bombardment with Ar cluster ions induced less surface damage than bombardment with Ar atomic ion. The damage layer thickness with 5 keV Ar cluster ion bombardment was less than 1 nm.

Yamamoto, Y.; Ichiki, K. [Department of Nuclear Engineering, Kyoto University, Sakyo, Kyoto, 606-8501 (Japan); Ninomiya, S.; Matsuo, J. [Quantum Science and Education Center, Gokasho, Uji, Kyoto, 611-0011 (Japan); CREST, Japan Science and Technology Agency (JST), Chiyoda, Tokyo, 102-0075 (Japan); Seki, T. [Department of Nuclear Engineering, Kyoto University, Sakyo, Kyoto, 606-8501 (Japan); CREST, Japan Science and Technology Agency (JST), Chiyoda, Tokyo, 102-0075 (Japan); Aoki, T. [Department of Electronic Science and Engineering, Kyoto University, Nishikyo, Kyoto, 615-8530 (Japan); CREST, Japan Science and Technology Agency (JST), Chiyoda, Tokyo, 102-0075 (Japan)

2011-01-07

290

Amorphization of nanocrystalline monoclinic ZrO2 by swift heavy ion irradiation.  

PubMed

Bulk ZrO(2) polymorphs generally have an extremely high amorphization tolerance upon low energy ion and swift heavy ion irradiation in which ballistic interaction and ionization radiation dominate the ion-solid interaction, respectively. However, under very high-energy irradiation by 1.33 GeV U-238, nanocrystalline (40-50 nm) monoclinic ZrO(2) can be amorphized. A computational simulation based on a thermal spike model reveals that the strong ionizing radiation from swift heavy ions with a very high electronic energy loss of 52.2 keV nm(-1) can induce transient zones with temperatures well above the ZrO(2) melting point. The extreme electronic energy loss, coupled with the high energy state of the nanostructured materials and a high thermal confinement due to the less effective heat transport within the transient hot zone, may eventually be responsible for the ionizing radiation-induced amorphization without transforming to the tetragonal polymorph. The amorphization of nanocrystalline zirconia was also confirmed by 1.69 GeV Au ion irradiation with the electronic energy loss of 40 keV nm(-1). These results suggest that highly radiation tolerant materials in bulk forms, such as ZrO(2), may be radiation sensitive with the reduced length scale down to the nano-metered regime upon irradiation above a threshold value of electronic energy loss. PMID:22858872

Lu, Fengyuan; Wang, Jianwei; Lang, Maik; Toulemonde, Marcel; Namavar, Fereydoon; Trautmann, Christina; Zhang, Jiaming; Ewing, Rodney C; Lian, Jie

2012-09-21

291

Cu Ions Irradiation Impact on Structural and Optical Properties of GaN Thin Film  

NASA Astrophysics Data System (ADS)

Epitaxial grown Gallium nitride (GaN) thin film on sapphire was irradiated with Cu ions at various fluences (5×1014, 1 ×1015 and 5×1015cm-2). The level of lattice disorder, as measured by Rutherford backscattering spectrometry and channeling (RBS/C), gradually increases with the increasing of ions fluence. Lattice amorphization is observed for the sample irradiated with fluence of 5×1015cm-2 which is also confirmed by X-ray diffractometer (XRD) analysis. It was found that both Raman modes of GaN layer clearly shifted with Cu+ fluences. Both Raman and X-ray analyses explore that Cu atom substituted into Ga sites. Atomic force microscopy (AFM) images show the irradiated GaN surface roughness increases with the increasing ions fluence. The UV-visible transmittance spectrum and ellipsometric measurements show a decrease in the band gap value after irradiation of Cu ions in the GaN film. Moreover, the optical constants (n and k) of the films vary with the increasing of Cu ion fluences.

Shah, A.; Husnain, G.; Ahmad, Ishaq; Mahmood, Arshad

2013-03-01

292

Ion beam irradiation of polytetrafluroethylene-loaded polyetheretherketone  

Microsoft Academic Search

Experiments were performed to study the radiation tolerance and mechanical stability of polytetrafluoroethylene (PTFE) loaded polyetheretherketone (PEEK) exposed to alpha particle radiation. Accelerator generated alpha beams were used to provide the extreme upper limit for the radiation environment of actinide sources where the polymer is employed in real applications. Before irradiation, a simplistic approach was used to determine possible exposures\\/doses

C. J. Wetteland; G. Gosnell; M. G. Hollander; J. R. Tesmer; R. Mooday; Y. Q. Wang

2006-01-01

293

Metal ion absorption of carboxymethylcellulose gel formed by ?-ray irradiation  

Microsoft Academic Search

Carboxymethylcellulose (CMC) is well known as a safe and biodegradable material, which is widely used as food additives, wash paste, etc., in our daily life. Aiming at the environmental purification of this eco-friendly substance, the authors have investigated Cu2+ absorption property of CMC gel that was crosslinked by irradiating with ?-rays without toxic crosslinker. The CMC gel has revealed to

K. Hara; M. Iida; K. Yano; T. Nishida

2004-01-01

294

Activated Ion Electron Capture Dissociation (AI ECD) of proteins: synchronization of infrared and electron irradiation with ion magnetron motion.  

PubMed

Here, we show that to perform activated ion electron capture dissociation (AI-ECD) in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with a CO(2) laser, it is necessary to synchronize both infrared irradiation and electron capture dissociation with ion magnetron motion. This requirement is essential for instruments in which the infrared laser is angled off-axis, such as the Thermo Finnigan LTQ FT. Generally, the electron irradiation time required for proteins is much shorter (ms) than that required for peptides (tens of ms), and the modulation of ECD, AI ECD, and infrared multiphoton dissociation (IRMPD) with ion magnetron motion is more pronounced. We have optimized AI ECD for ubiquitin, cytochrome c, and myoglobin; however the results can be extended to other proteins. We demonstrate that pre-ECD and post-ECD activation are physically different and display different kinetics. We also demonstrate how, by use of appropriate AI ECD time sequences and normalization, the kinetics of protein gas-phase refolding can be deconvoluted from the diffusion of the ion cloud and measured on the time scale longer than the period of ion magnetron motion. PMID:19200749

Mikhailov, Victor A; Cooper, Helen J

2009-05-01

295

Graphitic nanostripes in silicon carbide surfaces created by swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

The controlled creation of defects in silicon carbide represents a major challenge. A well-known and efficient tool for defect creation in dielectric materials is the irradiation with swift (Ekin?500?keV/amu) heavy ions, which deposit a significant amount of their kinetic energy into the electronic system. However, in the case of silicon carbide, a significant defect creation by individual ions could hitherto not be achieved. Here we present experimental evidence that silicon carbide surfaces can be modified by individual swift heavy ions with an energy well below the proposed threshold if the irradiation takes place under oblique angles. Depending on the angle of incidence, these grooves can span several hundreds of nanometres. We show that our experimental data are fully compatible with the assumption that each ion induces the sublimation of silicon atoms along its trajectory, resulting in narrow graphitic grooves in the silicon carbide matrix.

Ochedowski, Oliver; Osmani, Orkhan; Schade, Martin; Bussmann, Benedict Kleine; Ban-D'Etat, Brigitte; Lebius, Henning; Schleberger, Marika

2014-06-01

296

Temperature-ramped (129)Xe spin-exchange optical pumping.  

PubMed

We describe temperature-ramped spin-exchange optical pumping (TR-SEOP) in an automated high-throughput batch-mode (129)Xe hyperpolarizer utilizing three key temperature regimes: (i) "hot"-where the (129)Xe hyperpolarization rate is maximal, (ii) "warm"-where the (129)Xe hyperpolarization approaches unity, and (iii) "cool"-where hyperpolarized (129)Xe gas is transferred into a Tedlar bag with low Rb content (<5 ng per ?1 L dose) suitable for human imaging applications. Unlike with the conventional approach of batch-mode SEOP, here all three temperature regimes may be operated under continuous high-power (170 W) laser irradiation, and hyperpolarized (129)Xe gas is delivered without the need for a cryocollection step. The variable-temperature approach increased the SEOP rate by more than 2-fold compared to the constant-temperature polarization rate (e.g., giving effective values for the exponential buildup constant ?SEOP of 62.5 ± 3.7 × 10(-3) min(-1) vs 29.9 ± 1.2 × 10(-3) min(-1)) while achieving nearly the same maximum %PXe value (88.0 ± 0.8% vs 90.1% ± 0.8%, for a 500 Torr (67 kPa) Xe cell loading-corresponding to nuclear magnetic resonance/magnetic resonance imaging (NMR/MRI) enhancements of ?3.1 × 10(5) and ?2.32 × 10(8) at the relevant fields for clinical imaging and HP (129)Xe production of 3 T and 4 mT, respectively); moreover, the intercycle "dead" time was also significantly decreased. The higher-throughput TR-SEOP approach can be implemented without sacrificing the level of (129)Xe hyperpolarization or the experimental stability for automation-making this approach beneficial for improving the overall (129)Xe production rate in clinical settings. PMID:25008290

Nikolaou, Panayiotis; Coffey, Aaron M; Barlow, Michael J; Rosen, Matthew S; Goodson, Boyd M; Chekmenev, Eduard Y

2014-08-19

297

Structural phase transition in ZrO2 induced by swift heavy ion irradiation at high pressure  

E-print Network

Structural phase transition in ZrO2 induced by swift heavy ion irradiation at high pressure B ions reveals unexpected structural changes. Irradiated at ambient conditions, natural zirconia (ZrO2 and mechanical resistance and its radiation hardness. Because of these properties, ZrO2 is often used as inert

Paris-Sud XI, Université de

298

Static elasticity of cordierite I: Effect of heavy ion irradiation on the compressibility of hydrous cordierite  

NASA Astrophysics Data System (ADS)

The effect of ion beam irradiations on the elastic properties of hydrous cordierite was investigated by means of Raman and X-ray diffraction experiments. Oriented single crystals were exposed to swift heavy ions (Au, Bi) of various specific energies (10.0-11.1 MeV/u and 80 MeV/u), applying fluences up to 5 × 1013 ions/cm2. The determination of unit-cell constants yields a volume strain of 3.4 × 10-3 up to the maximum fluence, which corresponds to a compression of non-irradiated cordierite at ~480 ± 10 MPa. The unit-cell contraction is anisotropic ( e 1 = 1.4 ± 0.1 × 10-3, e 2 = 1.5 ± 0.1 × 10-3, and e 3 = 7 ± 1 × 10-4) with the c-axis to shrink only half as much as the axes within the ab-plane. The lattice elasticity for irradiated cordierite ( ? = 1 × 1012 ions/cm2) was determined from single-crystal XRD measurements in the diamond anvil cell. The fitted third-order Birch-Murnaghan equation-of-state parameters of irradiated cordierite ( V 0 = 1548.41 ± 0.16 Å3, K 0 = 117.1 ± 1.1 GPa, ? K/? P = -0.6 ± 0.3) reveal a 10-11 % higher compressibility compared to non-irradiated cordierite. While the higher compressibility is attributed to the previously reported irradiation-induced loss of extra-framework H2O, the anomalous elasticity as expressed by elastic softening ( ? {a/-1}, ? {b/-1}, ? {c/-1} = 397 ± 9, 395 ± 28, 308 ± 11 GPa, ?( ? -1)/? P = -4.5 ± 2.7, -6.6 ± 8.4, -5.4 ± 3.0) appears to be related to the framework stability and to be independent of the water content in the channels and thus of the ion beam exposure.

Miletich, R.; Scheidl, K. S.; Schmitt, M.; Moissl, A. P.; Pippinger, T.; Gatta, G. D.; Schuster, B.; Trautmann, C.

2014-09-01

299

Microstructural evolution of CANDU spacer material Inconel X-750 under in situ ion irradiation  

NASA Astrophysics Data System (ADS)

Work on Inconel®Inconel® is a registered trademark of Special Metals Corporation that refers to a family of austenitic nickel-chromium-based superalloys.1 X-750 spacers removed from CANDU®CANDU® is a registered trademark of Atomic Energy of Canada Limited standing for ''CANada Deuterium Uranium''.2 reactors has shown that they become embrittled and there is development of many small cavities within the metal matrix and along grain boundaries. In order to emulate the neutron irradiation induced microstructural changes, heavy ion irradiations (1 MeV Kr2+ ions) were performed while observing the damage evolution using an intermediate voltage electron microscope (IVEM) operating at 200 kV. The irradiations were carried out at various temperatures 60-400 °C. The principal strengthening phase, ??, was disordered at low doses (˜0.06 dpa) during the irradiation. M23C6 carbides were found to be stable up to 5.4 dpa. Lattice defects consisted mostly of stacking fault tetrahedras (SFTs), 1/2<1 1 0> perfect loops and small 1/3<1 1 1> faulted Frank loops. The ratio of SFT number density to loop number density for each irradiation condition was found to be neither temperature nor dose dependent. Under the operation of the ion beam the SFT production was very rapid, with no evidence for further growth once formed, indicating that they probably formed as a result of cascade collapse in a single cascade. The number density of the defects was found to saturate at low dose (˜0.68 dpa). No cavities were observed regardless of the irradiation temperature between 60 °C and 400 °C for doses up to 5.4 dpa. In contrast, cavities have been observed after neutron irradiation in the same material at similar doses and temperatures indicating that helium, produce during neutron irradiation, may be essential for the nucleation and growth of cavities.

Zhang, He Ken; Yao, Zhongwen; Judge, Colin; Griffiths, Malcolm

2013-11-01

300

Silicon ion irradiation effects on the magnetic properties of ion beam synthesized CoPt phase  

SciTech Connect

Ion beam mixing of Pt/Co bilayers using self ion (Pt{sup +}) beam results in formation of CoPt phase. Upon ion beam annealing the ion mixed samples using 4 MeV Si{sup +} ions at 300 deg. C, diffusion of Co towards the Pt/Co interface is observed. The Si{sup +} ion beam rotates the magnetization of the CoPt phase from in plane to out of plane of the film.

Balaji, S.; Amirthapandian, S.; Panigrahi, B. K.; Mangamma, G.; Kalavathi, S.; Gupta, Ajay; Nair, K. G. M. [Materials Science group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore.452 017 (India); Materials Science group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

2012-06-05

301

Synthesis of cobalt nanoparticles on Si (100) by swift heavy ion irradiation  

PubMed Central

We report the growth and characterization of uniform-sized nanoparticles of cobalt on n-type silicon (100) substrates by swift heavy ion (SHI) irradiation. The Co thin films of 25-nm thicknesses were grown by e-beam evaporation and irradiated with two different types of ions, 45-MeV Li3+ and 100-MeV O7+ ions with fluences ranging from 1 × 1011 to 1 × 1013 ions/cm2. SHI irradiation, with the beam rastered over the area of the film, resulted in the restructuring of the film into a dense array of Co nanostructures. Surface topography studied by atomic force microscopy revealed narrowed size distributions, with particle sizes ranging from 20 to 50 nm, formed through a self-organized process. Ion fluence-dependent changes in crystallinity of the Co nanostructures were determined by glancing angle X-ray diffraction. Rutherford backscattering spectroscopy analysis showed the absence of beam-induced mixing in this system. Surface restructuring and beam-induced crystallization are the dominant effects, with the nanoparticle size and density being dependent on the ion fluence. Results are analyzed in the context of molecular dynamics calculations of electron-lattice energy transfer. PMID:24138985

2013-01-01

302

Effect of low energy oxygen ion beam irradiation on ionic conductivity of solid polymer electrolyte  

SciTech Connect

Over the past three decades, solid polymer electrolytes (SPEs) have drawn significant attention of researchers due to their prospective commercial applications in high energy-density batteries, electrochemical sensors and super-capacitors. The optimum conductivity required for such applications is about 10{sup ?2} – 10{sup ?4} S/cm, which is hard to achieve in these systems. It is known that the increase in the concentration of salt in the host polymer results in a continuous increase in the ionic conductivity. However, there is a critical concentration of the salt beyond which the conductivity decreases due to formation of ion pairs with no net charge. In the present study, an attempt is made to identify the concentration at which ion pair formation occurs in PEO: RbBr. We have attempted to modify microstructure of the host polymer matrix by low energy ion (Oxygen ion, O{sup +1} with energy 100 keV) irradiation. Ionic conductivity measurements in these systems were carried out using Impedance Spectroscopy before and after irradiation to different fluencies of the oxygen ion. It is observed that the conductivity increases by one order in magnitude. The increase in ionic conductivity may be attributed to the enhanced segmental motion of the polymer chains. The study reveals the importance of ion irradiation as an effective tool to enhance conductivity in SPEs.

Manjunatha, H., E-mail: gnk-swamy@blr.amrita.edu; Kumaraswamy, G. N., E-mail: gnk-swamy@blr.amrita.edu [Department of Physics, Amrita Vishwa Vidyapeetham, Bengaluru-560035 (India); Damle, R. [Department of Physics, Bangalore University, Bengaluru-560056 (India)

2014-04-24

303

Analysis of ion-bombarded and laser-irradiated surfaces of ZnS and Zn via two-photon high-resolution laser-induced fluorescence spectroscopy  

SciTech Connect

Doppler-shifted two-photon laser-induced fluorescence spectroscopy (LFS) has been used for the first time to measure the velocity distributions of Zn atoms ejected by Ar/sup /plus// ion bombardment from both a Zn surface and a ZnS single crystal. Doppler-shifted spectroscopy in combination with time-of-flight, has also been employed to investigate Zn atoms ejected from a ZnS single crystal under irradiation by 308 nm photons (XeCl excimer laser). The absolute Zn sputtering yields from ion-bombarded and laser-irradiated ZnS samples were determined by comparison with LFS measurements of Zn atoms sputtered from pure Zn targets by Ar/sup /plus// ions since the absolute sputtering yield is known. For the Zn target the velocity distributions of the ion-induced sputtered Zn atoms were in good agreement with the Sigmund-Thompson distribution based on the known binding energy of 1.35 eV. On the other hand the velocity distribution of Zn atoms ion-sputtered from ZnS showed some deviation from the Sigmund-Thompson distribution and had a lower binding energy, /approximately/0.90 eV. The velocity distributions of the laser-ablated Zn atoms from ZnS were Maxwell-Boltzman in nature with characteristic temperatures increasing from 2000 to 9000 K at fluences of 20 and 80 mJ/cm/sup 2/, respectively. The absolute sputtering yield (Y) of Zn sputtered from ZnS was found to be Y /congruent/ 8.3 atoms/ion for ion sputtering and Y /congruent/ 10/sup /minus/6/ atoms/photon at a laser fluence of 30 mJ/cm/sup 2/ for laser ablation. High-resolution Doppler-shift techniques have been combined with TOF techniques. This promising combination permits unambiguous detection of prompt and delayed emission of ablated atoms, as well as the observation of possible molecular or cluster fragmentation. The results obtained indicate that no delayed emission is occurring and suggest the possibility of molecule or cluster emission from ZnS. 52 refs., 6 figs.

Arlinghaus, H.F.; Calaway, W.F.; Young, C.E.; Pellin, M.J.; Gruen, D.M.; Chase, L.L.

1988-08-01

304

Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties  

SciTech Connect

A cluster deposition method was used to produce films of loosely aggregated nanoclusters (NC) of Fe core-Fe3O4 shell or fully oxidized Fe3O4. Films of these NC on Si(100) or MgO(100)/Fe3O4(100) were irradiated to 1016 Si2+/cm2 near room temperature using an ion accelerator. Ion irradiation creates structural change in the NC film with corresponding chemical and magnetic changes which depend on the initial oxidation state of the cluster. Films were characterized using magnetometry (hysteresis, first order reversal curves), microscopy (transmission electron, helium ion), and x-ray diffraction. In all cases, the particle sizes increased due to ion irradiation, and when a core of Fe is present, irradiation reduces the oxide shells to lower valent Fe species. These results show that ion irradiated behavior of the nanocluster films depends strongly on the initial nanostructure and chemistry, but in general saturation magnetization decreases slightly.

McCloy, John S.; Jiang, Weilin; Droubay, Timothy C.; Varga, Tamas; Kovarik, Libor; Sundararajan, Jennifer A.; Kaur, Maninder; Qiang, You; Burks, Edward; Liu, Kai

2013-08-23

305

Probability of divacancy trap production in silicon diodes exposed to focused ion beam irradiation  

NASA Astrophysics Data System (ADS)

We present ion beam induced charge (IBIC) measurements of the critical displacement damage dose Dd values and modeling of the probability of divacancy trap production in p+-n-n+ silicon diodes exposed to megaelectron volt energy ion beam irradiation. The normalized induced charge (Q0/Q) measured by He ion probe in tested silicon diodes irradiated by focused He, Li, O, and Cl ion beams with energies of about 0.3 MeV/u increases linearly with Dd according to the modified radiation damage function and nonionizing energy loss (NIEL) theory. A simple IBIC model based on Gunn theorem showed clear dependence of the induced charge Q and corresponding equivalent damage factor Ked value on both a depth profile of charge created by ionizing particle (probe) and a depth distribution of stable defects created from primary defects produced by damaging ions. The average probability of the divacancy production (defined as the ratio of the final electrical active defect quantity and primary ion induced vacancy quantity for each impinging ion) of 0.18 (18%) was calculated by the IBIC modeling for all damaging ions.

Pastuovi?, Željko; Vittone, Ettore; Capan, Ivana; Jakši?, Milko

2011-02-01

306

Dual ion beam irradiation of polymeric materials for the modification of optical properties with improved adhesion  

NASA Astrophysics Data System (ADS)

Metallic (chromium) coating has often been applied on the surface of polymeric components, mainly to improve their appearance with a metallic luster and to protect from degradation under UV and visible light. However, the toxic nature of hexavalent chromium and delamination problems are an increasing concern in the plating industry. A similar metallic luster and the UV-visible light protection can be achieved by treating the surface of polymers by ion beams. However, a degradation by weathering including cracks, loss of glossiness, blistering, and eventual delamination have been problematic for ion beam processed polymers, particularly with a single ion beam irradiation. The main cause of adhesion failure is the abrupt change in material properties at the interface between coating and polymer or ion beam treated surface and the underlying untreated bulk polymer. In this work, therefore, a method is developed that improves adhesion by producing a graded interface by employing a dual ion beam processing. For demonstration purposes in this work, polycarbonate/acrylonitrile butadiene styrene blends were irradiated first with nitrogen ions followed by helium ions, achieving the desired metallic luster with improved adhesion. The experimental findings are explained in light of the stopping range of ions in materials and their interaction mechanisms with polymeric materials.

Park, Jae-Won; Lee, Eal H.; Lee, Jae-Sang; Lee, Byung-hoon; Kim, Min-kyu; Lee, Chan-Young; Kim, Hyung-jin; Choi, Byung-Ho

2012-06-01

307

Role of impact parameter in branching reactions: Chemical accelerator studies of the reaction Xe++CH4?XeCH3 ++H  

E-print Network

Integral reaction cross sections and product velocity distributions have been measured for the ion–molecule reaction Xe+(CH4,H)XeCH3 + over the relative reactant translational energy range of 0.7–5.5 eV by chemical accelerator techniques...

Miller, G. D.; Strattan, L. W.; Hierl, Peter M.

1981-01-01

308

Production and evolution of carbonaceous material by ion irradiation in space.  

PubMed

We review recent experimental studies concerning the evolution, driven by ion irradiation, of carbonaceous material from frozen gas to a refractory molecular solid. Under further irradiation the latter changes to a polymer-like material and ultimately to amorphous carbon. Most of the results have been obtained by "in situ" and remote IR and Raman spectroscopy. The results have been applied to demonstrate that molecular solids may be easily formed by irradiation of frozen mantles in dense interstellar clouds. Polymer-like material and amorphous carbons may result by further irradiation of organic mantles on grains in the diffuse interstellar medium. Those grains, during the aggregation to form extended bodies like comets (T-Tau phase of the Sun), are further modified. These latter are also irradiated, after the comet formation, during their long stay in the Oort cloud. In particular it has been suggested that comet may develop an ion-produced cometary organic crust that laboratory evidences show to be stable against temperature increases experienced during passages near the Sun. The comparison between the Raman spectra of some IDP (Interplanetary Dust Particles) and the Raman spectra of some ion-produced amorphous carbons, is also discussed. PMID:11539252

Strazzulla, G; Baratta, G A; Spinella, F

1995-03-01

309

Microstructure and Cs Behavior of Ba-Doped Aluminosilicate Pollucite Irradiated with F+ Ions  

SciTech Connect

Radionuclide 137Cs is one of the major fission products that dominate heat generation in spent fuels over the first 300 hundred years. A durable waste form for 137Cs that decays to 137Ba is needed to minimize its environmental impact. Aluminosilicate pollucite CsAlSi2O6 is selected as a model waste form to study the decay-induced structural effects. While Ba-containing precipitates are not present in charge-balanced Cs0.9Ba0.05AlSi2O6, they are found in Cs0.9Ba0.1AlSi2O6 and identified as monoclinic Ba2Si3O8. Pollucite is susceptible to electron irradiation induced amorphization. The threshold density of the electronic energy deposition for amorphization is determined to be ~235 keV/nm3. Pollucite can be readily amorphized under F+ ion irradiation at 673 K. A significant amount of Cs diffusion and release from the amorphized pollucite is observed during the irradiation. However, cesium is immobile in the crystalline structure under He+ ion irradiation at room temperature. The critical temperature for amorphization is not higher than 873 K under F+ ion irradiation. If kept at or above 873 K all the time, the pollucite structure is unlikely to be amorphized; Cs diffusion and release are improbable. A general discussion regarding pollucite as a potential waste form is provided in this report.

Jiang, Weilin; Kovarik, Libor; Zhu, Zihua; Varga, Tamas; Engelhard, Mark H.; Bowden, Mark E.; Nenoff, Tina M.; Garino, Terry

2014-08-07

310

Atomistic modeling of nanoscale patterning of L1{sub 2} order induced by ion irradiation  

SciTech Connect

Theoretical predictions indicate that ordered alloys can spontaneously develop a steady-state nanoscale microstructure when irradiated with energetic particles. This behavior derives from a dynamical competition between disordering in cascades and thermally activated reordering, which leads to self-organization of the chemical order parameter. We test this possibility by combining molecular dynamics (MD) and kinetic Monte Carlo (KMC) simulations. We first generate realistic distributions of disordered zones for Ni{sub 3}Al irradiated with 70 keV He and 1 MeV Kr ions using MD and then input this data into KMC to obtain predictions of steady state microstructures as a function of the irradiation flux. Nanoscale patterning is observed for Kr ion irradiations but not for He ion irradiations. We illustrate, moreover, using image simulations of these KMC microstructures, that high-resolution transmission electron microscopy can be employed to identify nanoscale patterning. Finally, we indicate how this method could be used to synthesize functional thin films, with potential for magnetic applications.

Ye Jia [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Lawrence Berkeley Laboratory, Berkeley, California 94720-8250 (United States); Li Youhong [Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Engineered Material Arresting Systems, Zodiac Aerospace, Logan Township, New Jersey 08085 (United States); Averback, Robert; Zuo Jianmin [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Bellon, Pascal [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2010-09-15

311

TEM investigation on the microstructural evolution of Hastelloy N induced by Ar? ion irradiation.  

PubMed

Hastelloy N alloy has been selected as the primary structure material for molten salt reactor. In this article, Hastelloy N alloy samples were irradiated to different doses at room temperature using 300 keV Ar(+) ions. The microstructural evolution was investigated by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). Black dot defects emerged in sample irradiated at low dose (0.4 displacement per atom (dpa)), and they grew up with irradiation doses (0.4-2 dpa). A high density of small dislocation loops (nano meters in size) were observed in the sample irradiated to 4 dpa. When the ion dose increased to 12 dpa, complicated structures with defects (including dislocation lines, larger loops and smaller black dots) were observed. Dislocation networks were detected from high-angle annular dark field (HAADF) images. Larger dislocation loops (size: 30-80 nm) were visible in the sample irradiated to 40 dpa. Irradiation with dose of 120 dpa led to the formation of face-centered cubic nanocrystallites with preferred orientations. PMID:24285574

Liu, Min; Lu, Yanling; Liu, Renduo; Zhou, Xingtai

2014-02-01

312

Carbon Ion Irradiation Inhibits Glioma Cell Migration Through Downregulation of Integrin Expression  

SciTech Connect

Purpose: To investigate the effect of carbon ion irradiation on glioma cell migration. Methods and Materials: U87 and Ln229 glioma cells were irradiated with photons and carbon ions. Migration was analyzed 24 h after irradiation. Fluorescence-activated cell sorting analysis was performed in order to quantify surface expression of integrins. Results: Single photon doses of 2 Gy and 10 Gy enhanced {alpha}{sub {nu}}{beta}{sub 3} and {alpha}{sub {nu}}{beta}{sub 5} integrin expression and caused tumor cell hypermigration on both vitronectin (Vn) and fibronectin (Fn). Compared to integrin expression in unirradiated cells, carbon ion irradiation caused decreased integrin expression and inhibited cell migration on both Vn and Fn. Conclusion: Photon radiotherapy (RT) enhances the risk of tumor cell migration and subsequently promotes locoregional spread via photon induction of integrin expression. In contrast to photon RT, carbon ion RT causes decreased integrin expression and suppresses glioma cell migration on both Vn and Fn, thus promising improved local control.

Rieken, Stefan, E-mail: Stefan.Rieken@med.uni-heidelberg.de [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Habermehl, Daniel; Wuerth, Lena [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Brons, Stephan [Heavy Ion Therapy Center, University Hospital of Heidelberg, Heidelberg (Germany); Mohr, Angela; Lindel, Katja; Weber, Klaus [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany); Haberer, Thomas [Heavy Ion Therapy Center, University Hospital of Heidelberg, Heidelberg (Germany); Debus, Juergen; Combs, Stephanie E. [Department of Radiation Oncology, University Hospital of Heidelberg, Heidelberg (Germany)

2012-05-01

313

Consequences of the ion beam irradiation on the chemical durability of Thorium Phosphate Diphosphate Kinetics study.  

E-print Network

, complexing reagents, flow rate, ...). The normalized dissolution rates depend significantly on the amorphous this later point, sintered samples of -TUPD solid solutions were pre-irradiated with ion beams with various the back-end of the nuclear fuel cycle defines their storage in an underground repository as a likely

Paris-Sud XI, Université de

314

Characterization and In-Situ Ion-Irradiation of MA957 ODS Steel Djamel Kaoumi1  

E-print Network

Characterization and In-Situ Ion-Irradiation of MA957 ODS Steel Djamel Kaoumi1 , Arthur Motta1/Martensitic steels produced by mechanical alloying with Y2O3 particles are considered as possible cladding materials--II #12;Fig. 1. (a) Bright Field TEM images of the grain microstructure in MA957 ODS steel in transversal

Motta, Arthur T.

315

Very low temperature (<400 "6) silicon molecular beam epitaxy: The role of low energy ion irradiation  

E-print Network

have studied Si molecular beam epitaxy (MBE) both with and without concurrent ion irradiation. Ther- mally grown films exhibit a high concentration of hydro- gen, especially in the disordered-built MBE system with a base pressure of less than 1X 10m7Pa. n-type Si(OO1) wafers with a miscut of less

Atwater, Harry

316

Effects of ion bombardment on a two-dimensional target: Atomistic simulations of graphene irradiation  

E-print Network

-functional theory models, we study effects of ion irradiation on graphene. We identify the types and concentrations are formed via in- plane recoils. We demonstrate that the conventional approach based on binary-collision in the sample. In bulk materials, after nearly half- century-long intensive research,8 the concentration

Krasheninnikov, Arkady V.

317

Amorphization and reduction of thermal conductivity in porous silicon by irradiation with swift heavy ions  

SciTech Connect

In this article, we demonstrate that the thermal conductivity of nanostructured porous silicon is reduced by amorphization and also that this amorphous phase in porous silicon can be created by swift (high-energy) heavy ion irradiation. Porous silicon samples with 41%-75% porosity are irradiated with 110 MeV uranium ions at six different fluences. Structural characterisation by micro-Raman spectroscopy and SEM imaging show that swift heavy ion irradiation causes the creation of an amorphous phase in porous Si but without suppressing its porous structure. We demonstrate that the amorphization of porous silicon is caused by electronic-regime interactions, which is the first time such an effect is obtained in crystalline silicon with single-ion species. Furthermore, the impact on the thermal conductivity of porous silicon is studied by micro-Raman spectroscopy and scanning thermal microscopy. The creation of an amorphous phase in porous silicon leads to a reduction of its thermal conductivity, up to a factor of 3 compared to the non-irradiated sample. Therefore, this technique could be used to enhance the thermal insulation properties of porous Si. Finally, we show that this treatment can be combined with pre-oxidation at 300 Degree-Sign C, which is known to lower the thermal conductivity of porous Si, in order to obtain an even greater reduction.

Newby, Pascal J. [Institut des Nanotechnologies de Lyon, Universite de Lyon, INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Institut Interdisciplinaire d'Innovation Technologique (3IT), Universite de Sherbrooke, CNRS UMI-LN2, Sherbrooke, Quebec J1K0A5 (Canada); Canut, Bruno; Bluet, Jean-Marie; Lysenko, Vladimir [Institut des Nanotechnologies de Lyon, Universite de Lyon, INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Gomes, Severine [Centre de Thermique de Lyon, Universite de Lyon, CETHIL-UMR5008, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Isaiev, Mykola; Burbelo, Roman [Faculty of Physics, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrs'ka St., Kyiv 01601 (Ukraine); Termentzidis, Konstantinos [Laboratoire LEMTA, Universite de Lorraine-CNRS UMR 7563, 54506 Vandoeuvre-les-Nancy cedex (France); Chantrenne, Patrice [Universite de Lyon, INSA de Lyon, MATEIS-UMR CNRS 5510, Villeurbanne 69621 (France); Frechette, Luc G. [Institut Interdisciplinaire d'Innovation Technologique (3IT), Universite de Sherbrooke, CNRS UMI-LN2, Sherbrooke, Quebec J1K0A5 (Canada)

2013-07-07

318

Key Contributions to the Cross Section of NAND Flash Memories Irradiated With Heavy Ions  

Microsoft Academic Search

Heavy-ion irradiation of NAND flash memories under operating conditions leads to errors with complex, data-dependent signatures. We present upsets due to hits in the floating gate array and in the peripheral circuitry, discussing their peculiarities in terms of pattern dependence and annealing. We also illustrate single event functional interruptions, which lead to errors during erase and program operations. To account

Marta Bagatin; Simone Gerardin; Giorgio Cellere; Alessandro Paccagnella; Angelo Visconti; Silvia Beltrami; Reno Harboe-Sorensen; Ari Virtanen

2008-01-01

319

Microstructural changes induced by low energy heavy ion irradiation in titanium silicon carbide  

E-print Network

Microstructural changes induced by low energy heavy ion irradiation in titanium silicon carbide. Benabdesselamf a École Nationale Supérieure des Mines, SPIN/PMMC, LPMG UMR CNRS 5148, 158 cours Fauriel, 42023 Saint- Étienne cedex 2, France b École Nationale Supérieure des Mines, SMS/MPM, PECM UMR CNRS 5146, 158

Boyer, Edmond

320

In-situ Study of Nanostructure and Electrical Resistance of Nanocluster Films Irradiated with Ion Beams  

SciTech Connect

An in-situ study is reported on the structural evolution in nanocluster films under He+ ion irradiation using an advanced helium ion microscope. The films consist of loosely interconnected nanoclusters of magnetite or iron-magnetite (Fe-Fe3O4) core-shells. The nanostructure is observed to undergo dramatic changes under ion-beam irradiation, featuring grain growth, phase transition, particle aggregation, and formation of nanowire-like network and nano-pores. Studies based on ion irradiation, thermal annealing and election irradiation have indicated that the major structural evolution is activated by elastic nuclear collisions, while both electronic and thermal processes can play a significant role once the evolution starts. The electrical resistance of the Fe-Fe3O4 films measured in situ exhibits a super-exponential decay with dose. The behavior suggests that the nanocluster films possess an intrinsic merit for development of an advanced online monitor for neutron radiation with both high detection sensitivity and long-term applicability, which can enhance safety measures in many nuclear operations.

Jiang, Weilin; Sundararajan, Jennifer A.; Varga, Tamas; Bowden, Mark E.; Qiang, You; McCloy, John S.; Henager, Charles H.; Montgomery, Robert O.

2014-08-11

321

MeV H+ ion irradiation effect on the stoichiometry of polyethylene terephthalate films  

NASA Astrophysics Data System (ADS)

Appropriate experimental conditions have been chosen to investigate the influence of main H+ ion irradiation parameters on stoichiometry changes induced in polyethylene terephthalate (PET) thin films. Stacks of six self-supporting identical films were irradiated perpendicularly to the target surface. Thus, the irradiations were realized simultaneously at different values of the target electronic stopping power, ?+. Indeed, the initial H+ ion energy of 1.1 MeV incident on the front polymer film was degraded down to 0.48 MeV at the entrance of the rear stacked film, which corresponds to an increase of ?+ from ˜0.22 up to ˜0.41 MeV cm2 mg-1. Ion fluences in the range (0.05-4) × 1015 cm-2 corresponding to an ion dose interval 1.80-263 MGy were used. The (H, O, C) atomic surface densities of the PET polymeric films were quantitatively determined by IBA techniques using a 1.62 MeV deuteron beam leading to the following main results: for each target film stacked at a given position thus fixed ?+, the oxygen atomic density decreases linearly versus ion fluence, ?; for the different ?+, the hydrogen impoverishment of the PET target is insignificant below critical fluence ?c ˜ 1.5 × 1015 cm-2 and becomes substantial above ?c; for fixed ?, the hydrogen and oxygen atomic densities exhibit linear decreases versus ?+; all measured such data versus ? and ?+ merge together into a unique decreasing curve for each (H, O, C) polymer content element when represented in function of the H+ ion dose, D, tightly correlating the latter two parameters; the O content element release from the PET target appears to be the most important, followed by the H content depletion, while the target C content is least affected under H+ ion irradiation.

Abdesselam, M.; Muller, D.; Djebara, M.; Ouichaoui, S.; Chami, A. C.

2013-07-01

322

Particle Accelerator Applications: Ion and Electron Irradiation in Materials Science, Biology and Medicine  

NASA Astrophysics Data System (ADS)

Although the developments of particle accelerators are devoted to basic study of matter constituents, since the beginning these machines have been applied with different purposes in many areas also. Today particle accelerators are essential instruments for science and technology. This work presents an overview of the main application for direct particle irradiation with accelerator in material science, biology and medicine. They are used for material synthesis by ion implantation and charged particle irradiation; to make coatings and micromachining; to characterize broad kind of samples by ion beam analysis techniques; as mass spectrometers for atomic isotopes determination. In biomedicine the accelerators are applied for the study of effects by charged particles on cells. In medicine the radiotherapy by electron irradiation is widely used, while hadrontherapy is still under development. Also, they are necessary for short life radioisotopes production required in radiodiagnostic.

Rodríguez-Fernández, Luis

2010-09-01

323

Plant height revertants of Dominant Semidwarf mutant rice created by low-energy ion irradiation  

NASA Astrophysics Data System (ADS)

Dominant Semidwarf mutant rice (Sdd) was obtained from its wild type (WT) by irradiation with a low-energy ion beam. Six tall revertants of Sdd were induced by irradiation. The revertants restored the plant height to that of WT plants. Investigation of the agronomic character and genetic analysis indicate that the revertants are similar to WT plants with putative different inherited mutations. The revertants were checked for DNA differences using the simple sequence repeat technique. Among 408 such primers used, only 2 primers detected mutation sites in the revertants, which provided the molecular evidence for the revertants induced from Sdd. This study indicates that ion irradiation may be used as a mutagen to create revertants for plant architecture studies and could be a new application.

Liu, Binmei; Wu, Yuejin; Xu, Xue; Song, M.; Zhao, M.; Fu, X. D.

2008-04-01

324

RBS/Channeling Studies of Swift Heavy Ion Irradiated GaN Layers  

NASA Astrophysics Data System (ADS)

Epitaxial GaN layers grown by MOCVD on c-plane sapphire substrates were irradiated with 150 MeV Ag ions at a fluence of 5×1012ions/cm2. Samples used in this study are 2 ?m thick GaN layers, with and without a thin AlN cap-layer. Energy dependent RBS/Channeling measurements have been carried out on both irradiated and unirradiated samples for defects characterization. Observed results are compared and correlated with previous HRXRD, AFM and optical studies. The ?min values for unirradiated samples show very high value and the calculated defect densities are of the order of 1010 cm?2 as expected in these samples. Effects of irradiation on these samples are different as initial samples had different defect densities. Epitaxial reconstruction of GaN buffer layer has been attributed to the observed changes, which are generally grown to reduce the strain between GaN and Sapphire

Sathish, N.; Dhamodaran, S.; Pathak, A. P.; Muntele, C.; Ila, D.; Khan, S. A.; Avasthi, D. K.

2009-03-01

325

In situ transmission electron microscopy and ion irradiation of ferritic materials.  

PubMed

The intermediate voltage electron microscope-tandem user facility in the Electron Microscopy Center at Argonne National Laboratory is described. The primary purpose of this facility is electron microscopy with in situ ion irradiation at controlled sample temperatures. To illustrate its capabilities and advantages a few results of two outside user projects are presented. The motion of dislocation loops formed during ion irradiation is illustrated in video data that reveals a striking reduction of motion in Fe-8%Cr over that in pure Fe. The development of extended defect structure is then shown to depend on this motion and the influence of nearby surfaces in the transmission electron microscopy thin samples. In a second project, the damage microstructure is followed to high dose (200 dpa) in an oxide dispersion strengthened ferritic alloy at 500 degrees C, and found to be qualitatively similar to that observed in the same alloy neutron irradiated at 420 degrees C. PMID:19189372

Kirk, Marquis A; Baldo, Peter M; Liu, Amelia C Y; Ryan, Edward A; Birtcher, Robert C; Yao, Zhongwen; Xu, Sen; Jenkins, Michael L; Hernandez-Mayoral, Mercedes; Kaoumi, Djamel; Motta, Arthur T

2009-03-01

326

Microstructure evolution of zircaloy-4 during Ne ion irradiation and annealing: An in situ TEM investigation  

NASA Astrophysics Data System (ADS)

The microstructural evolution of zircaloy-4 was studied, including the amorphization and recrystallization of Zr(Fe, Cr)2 precipitates, and the density of dislocations under in situ Ne ion irradiation and post annealing. The results show that irradiation at a relatively high temperature and dose induces the formation of nanocrystals in pre-amorphized Zr(Fe, Cr)2precipitates. The recrystallized nanocrystals also have the structure of hcp-Zr(Fe, Cr)2. The formation of the nanocrystals is thought to be the consequence of competition between atomistic disordering and the recrystallization of precipitates under ion irradiation. The free energy of the nanocrystal is lower than that of the amorphous state, which is another reason for the recrystallization of the precipitates. With increased annealing temperature, the density of the nanocrystals is increased. The dislocation density sharply decreases with the increase in the annealing temperature, and its size increases.

Shen, Hua-Hai; Peng, Shu-Ming; Zhou, Xiao-Song; Sun, Kai; Wang, Lu-Ming; Zu, Xiao-Tao

2014-03-01

327

Annealing effects on the photoluminescence of Pb-ion irradiated He-doped sapphire  

NASA Astrophysics Data System (ADS)

In the present work, the photoluminescence (PL) character of single crystal sapphire (Al2O3) samples with and without implantation by 110 keV He and/or irradiation by 230-MeV Pb ions, as well as subsequently annealing at 600, 900 and 1100 K ( T A) was studied. The modification of the structure and optical properties induced by ion irradiation were analyzed by using PL and FTIR spectra. The PL measurements showed that luminescence peaks located at 390, 413, 450, and 564 nm appeared in irradiated samples. The luminescence peaks appeared at 360, 380, and 516 nm after annealing. Infrared spectra showed a broadening of the absorption band between 460 cm-1 and 510 cm-1, which indicated the formation of strongly damaged regions in the Al2O3 samples. The position shift of the absorption band in 1000-1300 cm-1 tended towards to a higher wavelength.

Song, Yin; Zhang, ChongHong; He, DeYan; Zhang, LiQing; Gou, Jie; Yang, YiTao; Li, JianJian

2012-10-01

328

Xe isotopic fractionation in a cathodeless glow discharge. [for carbonaceous meteoritic composition studies  

NASA Technical Reports Server (NTRS)

Results are reported on the isotopic composition of Xe processed in cathodeless glow discharges in rarefied air at pressures of 20-40 microns Hg, in the presence of activated charcoal and in empty pyrex containers. Residual gas phase Xe and trapped Xe were found to be fractionated, with the trapped Xe fractionated up to 1 percent per amu. A model is presented for the fractionating process in which Xe ions are simultaneously implanted and sputtered from substrate material, with a mass dependence favoring retention of the heavy isotopes in the substrate. Results of the investigation show that plasma synthesis of carbonaceous material is unnecessary for producing Xe fractionations, and that the fractionations observed in previous synthesis experiments are probably due to implantation of ions into the synthesized material.

Bernatowicz, T. J.; Fahey, A. J.

1986-01-01

329

Modification and nano-patterning of high-Tc superconducting thin films by masked ion beam irradiation  

NASA Astrophysics Data System (ADS)

Ion irradiation of the high-temperature superconductor (HTS) YBa2Cu3O7 (Y-123) creates different types of defects depending on ion mass, energy and dose. Irradiation with helium ions of moderate energy (75 keV) primarily creates point defects. We measure in situ the modification of electrical transport properties of Y-123 thin films (thickness 310 nm) during ion irradiation. The He ions penetrate thin films and produce collision cascades with small lateral straggle that allow for patterning of nanostructures in the HTS layer. We present features smaller than 100 nm in size produced by masked ion beam irradiation of Y-123 films. Computer simulations indicate that nano-patterning of Y-123 thin films with 10 nm lateral resolution is achievable.

Bodea, M. A.; Pedarnig, J. D.; Siraj, K.; Behbood, N.; Bäuerle, D.; Lang, W.; Hasenfuss, C.; Palmetshofer, L.; Haselgrübler, K.; Kolarova, R.; Bauer, P.

2010-06-01

330

1\\/ f noise studies of swift heavy ion irradiated magnetite thin films  

Microsoft Academic Search

The effect of 190MeV 107Ag ion irradiation on antiphase boundaries (APBs) of epitaxial Fe3O4 thin films (thickness ?70nm) grown on MgO (100) oriented substrate has been investigated. The X-ray diffraction shows that at low fluence values upto 5×1011ions\\/cm2, the strain in the films is relaxed whereas at high fluence 1×1012ions\\/cm2, the epitaxial relationship with the substrate is decreasing. The low

M. Wasi Khan; Ravi Kumar; J. P. Srivastava; S. K. Arora; R. J. Choudhary; I. V. Shvets

2008-01-01

331

Iron ion irradiation increases promotes adhesion of monocytic cells to arterial vascular endothelium  

NASA Astrophysics Data System (ADS)

Radiation causes inflammation, and chronic, low-level vascular inflammation is a risk factor for atherosclerosis. Consistent with this, exposure to radiation from a variety of sources is associated with increased risk of heart disease and stroke. Part of the inflammatory response to radiation is a change in the adhesiveness of the endothelial cells that line the blood vessels, triggering inappropriate accumulation of leukocytes, leading to later, damaging effects of inflammation. Although some studies have been done on the effects of gamma irradiation on vascular endothelium, the response of endothelium to heavy ion radiation likely to be encountered in prolonged space flight has not been determined. We investigated how irradiation of aortic endothelial cells with iron ions affects adhesiveness of cultured aortic endothelial cells for monocytic cells and the consequences of this for development of atherosclerosis. Aortic endothelial cells were irradiated with 600 MeV iron ions at Brookhaven National Laboratory and adhesion-related changes were measured. Cells remained viable for at least 72 hours, and were even able to repair acute damage to cell junctions. We found that iron ion irradiation altered expression levels of specific endothelial cell adhesion molecules. Further, these changes had functional consequences. Using a flow chamber adhesion assay to measure adhesion of monocytic cells to endothelial cells under physiological shear stress, we found that adhesivity of vascular endothelium was enhanced in as little as 24 hours after irradiation. Further, the radiation dose dependence was not monotonic, suggesting that it was not simply the result of endothelial cell damage. We also irradiated aortic arches and carotid arteries of Apolipoprotein-E-deficient mice. Histologic analysis of these mice will be conducted to determine whether effects of radiation on endothelial adhesiveness result in consequences for development of atherosclerosis. (Supported by NSBRI: NCC-9-58-162)

Kucik, Dennis; Khaled, Saman; Gupta, Kiran; Wu, Xing; Yu, Tao; Chang, Polly; Kabarowski, Janusz

332

A new method for modifying metallic materials by ion irradiation  

Microsoft Academic Search

A new method of radiation surface modification of metal materials is proposed. The method permits to apply the equipment, which is usually employed for ion implantation or plasma treatment with minimum and cheap constructive changes. But the substantially more high characteristics of materials can be obtained as compared with other radiation hardening methods due to the different base principles. The

Davit Danielyan

333

In situ creep measurements on micropillar samples during heavy ion irradiation  

NASA Astrophysics Data System (ADS)

We report on the development of an in situ micropillar compression apparatus capable of measuring creep under heavy ion beam irradiation. The apparatus has a force resolution of 1 ?N and a displacement resolution of 1 nm. The experimental setup consists of a nanopositioner, a laser displacement sensor, and a microfabricated doubly clamped silicon-beam transducer. The system was tested by measuring the creep rate of amorphous Cu56Ti38Ag6 micropillars as a function of applied stress during room temperature irradiation with 2.1 MeV Ne+. Measured values of the irradiation induced fluidity are in the range 0.5-3 dpa-1 GPa-1, and in good agreement with values obtained by stress relaxation experiments on other metallic glasses, and with predictions of molecular dynamics simulations. The in situ apparatus provides a practical approach for accelerated evaluation of irradiation induced creep in promising nuclear materials.

Özerinç, Sezer; Averback, Robert S.; King, William P.

2014-08-01

334

Inactivation, DNA double strand break induction and their rejoining in bacterial cells irradiated with heavy ions  

NASA Technical Reports Server (NTRS)

Besides inactivation one of the major interests in our experiments is to study the primary damage in the DNA double strand breaks (DSB) after heavy ion irradiation. These damages lead not only to cell death but also under repair activities to mutations. In further experiments we have investigated the inactivation with two different strains of Deinococcus radiodurans (R1, Rec 30) and the induction of DSB as well as the rejoining of DSB in stationary cells of E. coli (strain B/r) irradiated with radiations of different quality. In the latter case irradiations were done so that the cell survival was roughly at the same level. We measured the DSB using the pulse field gelelectrophoresis which allows to separate between intact (circular) and damaged (linear) DNA. The irradiated cells were transferred to NB medium and incubated for different times to allow rejoining.

Schaefer, M.; Zimmermann, H.; Schmitz, C.

1994-01-01

335

Formation and evolution of ripples on ion-irradiated semiconductor surfaces  

SciTech Connect

We have examined the formation and evolution of ripples on focused-ion-beam (FIB) irradiated compound semiconductor surfaces. Using initially normal-incidence Ga{sup +} FIB irradiation of InSb, we tuned the local beam incidence angle (?{sub eff}) by varying the pitch and/or dwell time. For single-pass FIB irradiation, increasing ?{sub eff} induces morphological evolution from pits and islands to ripples to featureless surfaces. Multiple-pass FIB irradiation of the rippled surfaces at a fixed ?{sub eff} leads to island formation on the ripple crests, followed by nanorod (NR) growth. This ripple-NR transition provides an alternative approach for achieving dense arrays of NRs.

Kang, M.; Wu, J. H.; Ye, W.; Jiang, Y.; Robb, E. A.; Chen, C.; Goldman, R. S., E-mail: rsgold@umich.edu [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)

2014-02-03

336

Amorphization and recrystallization of single-crystalline hydrogen titanate nanowires by N{sup +} ion irradiation  

SciTech Connect

We report on the phase transformation of hydrogen titanate (H{sub 2}Ti{sub 3}O{sub 7}) nanowires induced by 50?keV N{sup +} ion irradiation at room temperature with fluences of 1?×?10{sup 15} ions/cm{sup 2} and 1?×?10{sup 16} ions/cm{sup 2}, respectively. Using transmission electron microscopy, the internal structure of the ion irradiated nanowires is analyzed. At low fluence, a transformation from crystalline H{sub 2}Ti{sub 3}O{sub 7} to amorphous TiO{sub 2} is observed. However, at higher fluence, a remarkable crystalline-amorphous TiO{sub 2} core-shell structure is formed. At this higher fluence, the recrystallization occurs in the core of the nanowire and the outer layer remains amorphous. The phase transformation and formation of core-shell structure are explained using the thermal spike model, radiation enhanced diffusion, and classical theory of nucleation and growth under non-equilibrium thermodynamics. X-ray photoelectron spectroscopy and Raman scattering reveal further insight into the structure of the nanowires before and after ion irradiation.

Behera, Akshaya K.; Bandyopadyay, Malay K.; Chatterjee, Shyamal, E-mail: shyamal@iitbbs.ac.in [School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar 751007 (India); Facsko, Stefan [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden (Germany); Das, Siddhartha [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

2014-06-21

337

Thermal conductivity degradation induced by heavy ion irradiation at room temperature in ceramic materials  

NASA Astrophysics Data System (ADS)

The thermal conductivity degradation induced by irradiation with energetic heavy ions at room temperature is studied and quantified. Three semi-metallic systems: titanium and zirconium carbides, titanium nitride, as well as a covalent compound: 6H silicon carbide were irradiated by 25.8 MeV krypton ions at 1016 and 6 \\cdot 1016 ions.cm-2 doses to produce defects. During ion irradiation, inelastic collisions and elastic collisions occur at a different depth in a material. Two collision domains can be defined. Modulated thermoreflectance microscopy measurements were performed at differing frequencies to characterize the thermal conductivity degradation in these two domains for each of the investigated materials. Our results reveal a significant thermal conductivity degradation in the two collision domains for all materials. Elastic collisions are shown to degrade more strongly the thermal properties than inelastic ones. Scattering of thermal energy carriers is larger in elastic collision domain because displacement cascades produce a very high concentration of point defects: vacancies, interstitials and implanted Kr ions. The degradation coming from electronic interactions that seems to be more important in SiC can be explained by the presence of large populations of generated extended defects, facing to generated individual point defects in TiC, TiN or ZrC.

Gomès, S.; David, L.; Roger, J.-P.; Carlot, G.; Fournier, D.; Valot, C.; Raynaud, M.

2008-01-01

338

Wet etching of GaN damaged by heavy ion irradiation  

NASA Astrophysics Data System (ADS)

Defects in GaN films can be revealed by wet etching in hot H 3PO 4 and molten potassium hydroxide or by photoelectrochemical (PEC) etching. GaN film was irradiated by 500 keV Au ions with ion fluences in the range from 1 × 10 9/cm 2 to 5 × 10 15/cm 2. Afterwards, AZ-400 K photoresist developer and aqueous KOH were used for wet etching of GaN at a relatively low temperature of 80 °C. With this method, defects in GaN films, after being irradiated by heavy ions, can be revealed with an etch pit density of 10 6-10 8/cm 2, the same magnitude with that in as-grown GaN films. Additionally, the etched pits present different features at different ion fluences. Our experimental results indicate that heavy ion irradiation can enhance the wet etching of GaN films at the sites having original defects. The related mechanism was also discussed in this paper.

Li, Juan; Gao, Yuan; Zhang, Weiming; Yan, Sha; Xue, Jianming; Wang, Yugang

2008-06-01

339

Plastic deformation in SiO 2 induced by heavy-ion irradiation  

NASA Astrophysics Data System (ADS)

Samples of vitreous silica and quartz were irradiated by different high-energy heavy ions at various temperatures. The dimensions of the samples were measured at room temperature before and after irradiation with different fluences. In the low-fluence range vitreous silica exhibits a long-known compaction which saturates at a density increase of about 3%. In the high-fluence range vitreous silica is, like other amorphous materials, subject to radiation-induced plastic deformation: the dimensions perpendicular to the ion beam grow without tendency to saturation whereas the dimension parallel to it shrinks. The deformation yield per incident ion is the higher, the lower the temperature and the larger the electronic energy loss. The samples of quartz are amorphized in the low-fluence range and subsequently undergo plastic deformation in the same way as vitreous silica. A model describing this plastic deformation is proposed and compared to the experimental results.

Benyagoub, A.; Löffler, S.; Rammensee, M.; Klaumünzer, S.; Saemann-Ischenko, G.

1992-03-01

340

XeF2 vapor phase silicon etch used in the fabrication of movable SOI structures  

Microsoft Academic Search

Vapor phase XeF has been used in the fabrication of various types of devices including MEMS, resonators, RF switches, and micro-fluidics, and for wafer level packaging. In this presentation we demonstrate the use of XeF Si etch in conjunction with deep reactive ion etch (DRIE) to release single crystal Si structures on Silicon On Insulator (SOI) wafers. XeF vapor phase

M. Wiwi; Carlos Anthony Sanchez; Thomas Alvin Plut; M. Salazar; Jeffrey Stevens; Todd M. Bauer; C. Ford; Randy John Shul; Grant David Grossetete

2010-01-01

341

Irradiation effects of 12 eV oxygen ions on polyimide and fluorinated ethylene propylene  

NASA Astrophysics Data System (ADS)

Polyimide (PI) and Fluorinated Ethylene Propylene (FEP) samples (15mm x 15mm x 50 mu m ) were exposed to atomic oxygen ions of average energy similar to 12 eV and flux similar to 5x10(13) ions cm(-2) s(-1) , produced in the Electron Cyclotron Resonance (ECR) plasma. The energy and the flux of the oxygen ions at different positions in the plasma were measured by a retarding field analyzer. The fluence of the oxygen ions was varied from sample to sample in the range of similar to 5x10(16) to 2x10(17) ions cm(-2) by changing the irradiation period. The pre- and the post-irradiated samples were characterized by the weight loss, Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared (FTIR) techniques. The weight of the PI and FEP samples decreased with increasing the ion fluence. However, the erosion yield for the PI is found to be higher, by almost a factor five, when compared with that of FEP. On the surface region of irradiated samples, the concentrations of the carbon, fluorine, and oxygen and their corresponding chemical bonds have changed appreciably. Moreover, blisters and nanoglobules were also observed even at a fluence of similar to 10(17) ions cm(-2) . This oxygen ion fluence is almost two orders of magnitude lower than that of the 5 eV atomic oxygen, which a satellite encounters in the space, at the low Earth orbit, during its mission period of about 7 years.

Majeed, R. M. A.; Purohit, V. S.; Bhoraskar, S. V.; Mandale, A. B.; Bhoraskar, V. N.

2006-08-01

342

Microstructural evolution of P92 ferritic/martensitic steel under argon ion irradiation  

SciTech Connect

Microstructural evolution of P92 ferritic/martensitic steel irradiated by Ar{sup +} ion beams at doses from 0.6 to 230 displacements per atom (dpa) at room temperature was investigated with conventional transmission electron microscope technique. Selected-area electron diffraction combined with bright-field and dark-field contrast image indicated that carbide/matrix interfaces were more easily damaged. The carbide peripheries became partly amorphous at irradiation dose of 2.3 dpa and were almost complete amorphous at the dose of 11.5 dpa. The small carbides would re-precipitate in matrices at 34.5 dpa. Energy dispersive X-ray analysis revealed that segregation of Cr and W and depletion of Fe in carbides occurred under irradiation. With the irradiation dose increasing, the irradiation induced segregation and depletion became more severe, which would influence mechanical properties of the steel. - Research Highlights: {yields} Carbide/matrix interfaces in P92 ferritic/martensitic steel were easily damaged. {yields} Small carbides re-precipitated in matrices after higher dose irradiation. {yields} Segregation of Cr and W and depletion of Fe in carbides occurred after irradiation.

Jin, S.X. [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Guo, L.P., E-mail: guolp@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Yang, Z.; Fu, D.J.; Liu, C.S. [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Tang, R. [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chendu 610041 (China); Liu, F.H.; Qiao, Y.X.; Zhang, H.D. [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China)

2011-01-15

343

Chemi-luminescence measurements of hyperthermal Xe{sup +}/Xe{sup 2+}+ NH{sub 3} reactions  

SciTech Connect

Luminescence spectra are recorded for the reactions of Xe{sup +}+ NH{sub 3} and Xe{sup 2+}+ NH{sub 3} at energies ranging from 11.5 to 206 eV in the center-of-mass (E{sub cm}) frame. Intense features of the luminescence spectra are attributed to the NH (A {sup 3}{Pi}{sub i}-X {sup 3}{Sigma}{sup -}), hydrogen Balmer series, and Xe I emission observable for both primary ions. Evidence for charge transfer products is only found through Xe I emission for both primary ions and NH{sup +} emission for Xe{sup 2+} primary ions. For both primary ions, the absolute NH (A-X) cross section increases with collision energy before leveling off at a constant value, approximately 9 x 10{sup -18} cm{sup 2}, at about 50 eV while H-{alpha} emission increases linearly with collision energy. The nascent NH (A) populations derived from the spectral analysis are found to be independent of collision energy and have a constant rotational temperature of 4200 K.

Prince, Benjamin D.; Steiner, Colby P. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States); Chiu, Yu-Hui [Busek Co. Inc, Natick, Massachusetts 01760 (United States)

2012-04-14

344

Dependence of cross sections for multi-electron loss by 6 mev/amu xe18+ ions on target atomic number  

E-print Network

Atomic or average atomic number H2 0-200 1.00 He 0-200 2.00 CH4 0-64 2.00 C3H8 0-64 2.36 SiH4 0-64 3.60 CO 0-64 7.00 N2 0-64 7.00 CO2 0-64 7.33 O2 0-64 8.00 C3F8 0-64 8.18 CF4 0-64 8.40 SF6 0-64 10.00 Ne 0-64 10.00 Ar 0-64 18.00 Kr 0-64 36.00 Xe 0-64 54... Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Rand L. Watson (Chair of Committee) John Reading (Member) Sherry J...

Peng, Yong

2004-09-30

345

Visualising discrete structural transformations in germanium nanowires during ion beam irradiation and subsequent annealing  

NASA Astrophysics Data System (ADS)

In this article we detail the application of electron microscopy to visualise discrete structural transitions incurring in single crystalline Ge nanowires upon Ga-ion irradiation and subsequent thermal annealing. Sequences of images for nanowires of varying diameters subjected to an incremental increase of the Ga-ion dose were obtained. Intricate transformations dictated by a nanowire's geometry indicate unusual distribution of the cascade recoils in the nanowire volume, in comparison to planar substrates. Following irradiation, the same nanowires were annealed in the TEM and corresponding crystal recovery followed in situ. Visualising the recrystallisation process, we establish that full recovery of defect-free nanowires is difficult to obtain due to defect nucleation and growth. Our findings will have large implications in designing ion beam doping of Ge nanowires for electronic devices but also for other devices that use single crystalline nanostructured Ge materials such as thin membranes, nanoparticles and nanorods.In this article we detail the application of electron microscopy to visualise discrete structural transitions incurring in single crystalline Ge nanowires upon Ga-ion irradiation and subsequent thermal annealing. Sequences of images for nanowires of varying diameters subjected to an incremental increase of the Ga-ion dose were obtained. Intricate transformations dictated by a nanowire's geometry indicate unusual distribution of the cascade recoils in the nanowire volume, in comparison to planar substrates. Following irradiation, the same nanowires were annealed in the TEM and corresponding crystal recovery followed in situ. Visualising the recrystallisation process, we establish that full recovery of defect-free nanowires is difficult to obtain due to defect nucleation and growth. Our findings will have large implications in designing ion beam doping of Ge nanowires for electronic devices but also for other devices that use single crystalline nanostructured Ge materials such as thin membranes, nanoparticles and nanorods. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04513k

Kelly, Roisin A.; Holmes, Justin D.; Petkov, Nikolay

2014-10-01

346

Crystallographically-dependent ripple formation on Sn surface irradiated with focused ion beam  

NASA Astrophysics Data System (ADS)

The metallographically polished polycrystalline Sn surface was sputtered by 30 kV focused Ga + ions at room temperature. The experiment was carried out using various FIB incidence angles (0°, 15°, 30°, and 45°) over a wide range of doses (10 16-10 18 ions/cm 2). The surface morphology was carefully characterized under the optical microscope, scanning electron microscope (SEM) and atomic force microscope (AFM). Ripples were observed on the irradiated areas even at the normal FIB incidence angle, which is not consistent with the Bradley-Harper (BH) rippling model. The orientation of ripples relies on crystallographic orientation rather than projected ion beam direction as predicted by BH model. The ripple wavelength is independent of ion dose, while ripple amplitude increases with ion dose. It is found that the ripples are formed by self-organization due to anisotropic surface diffusion in the low melting point metal.

Qian, H. X.; Zhou, W.; Fu, Y. Q.; Ngoi, B. K. A.; Lim, G. C.

2005-02-01

347

Temporal evolution of nanoporous layer in off-normally ion irradiated GaSb  

SciTech Connect

Room temperature irradiation of GaSb by 60?keV Ar{sup +}-ions at an oblique incidence of 60° leads to simultaneous formation of a nanoporous layer and undulations at the interface with the underlying substrate. Interestingly, with increasing ion fluence, a gradual embedding of the dense nanoporous layer takes place below ridge-like structures (up to the fluence of 1?×?10{sup 17} ions cm{sup ?2}), which get extended to form a continuous layer (at fluences ?4?×?10{sup 17} ions cm{sup ?2}). Systematic compositional analyses reveal the co-existence of Ga{sub 2}O{sub 3} and Sb{sub 2}O{sub 3} in the surface layer. The results are discussed in terms of a competition between ion-induced defect accumulation and re-deposition of sputtered atoms on the surface.

Datta, D. P.; Garg, S. K.; Som, T., E-mail: tsom@iopb.res.in [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751 005, Odisha (India); Kanjilal, A. [Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, Uttar Pradesh 203 207 (India); Sahoo, P. K. [School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751 005, Odisha (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

2014-03-28

348

Surface-plasmon-enhanced MeV ions from femtosecond laser irradiated, periodically modulated surfaces  

NASA Astrophysics Data System (ADS)

Enhanced emission of high energy ions is measured from sub-wavelength metallic grating targets under irradiation by intense (1015-1016 W cm-2), p-polarized, 50 fs, 800 nm laser pulses. The maximum ion energy is 55% higher and the ion flux is 60% higher for the modulated surface in comparison with polished surfaces of the same atomic composition. The ion emission, a result of enhanced light coupling and hot electron production in the grating targets, is correlated with enhancement in hard x-ray bremsstrahlung emission. The results are well reproduced by particle-in-cell simulations. The study reveals that the enhanced laser coupling by surface plasmon excitation on metallic gratings is directly responsible for the enhancement of ion energies.

Bagchi, Suman; Prem Kiran, P.; Wang, W.-M.; Sheng, Z. M.; Bhuyan, M. K.; Krishnamurthy, M.; Ravindra Kumar, G.

2012-03-01

349

I-Xe studies of the Acapulco meteorite: Absolute I-Xe ages of individual phosphate grains and the Bjurböle standard  

NASA Astrophysics Data System (ADS)

We have measured Kr and Xe by laser volatilization of seventeen individual neutron-irradiated phosphate grains (nine apatite and eight merrillite) separated from the (reclassified) A-chondrite Acapulco. Radiogenic 129Xe from now-extinct 129I is only observed in the apatites, which all formed simultaneously (8.1 ± 1.2 Ma) after Xe closure in the Bjurböle (L4) standard. This relative closure time, when coupled with the Pb-Pb age of Acapulco phosphates (4.557 ± 0.002 Ga) provides an absolute I-Xe age for these apatites, for Bjurböle and for all samples previously referenced to the Bjurböle standard, subject to the assumptions implicit in I-Xe dating. We have also measured Kr and Xe by stepwise heating of irradiated and unirradiated whole-rock samples of Acapulco and of unirradiated phosphate concentrates. Iodine-derived xenon in the irradiated whole-rock sample does not yield an I-Xe isochron, consistent with the presence of multiple iodine host phases previously observed. Xenon from the spontaneous fission of now-extinct 244Pu is observed in the single phosphate grains and the inferred initial ( 244Pu/ 238U) 0 ratios reflect fractionation of the actinides favoring plutonium in the merrillites and uranium in the apatites.

Nichols, Robert H., Jr.; Hohenberg, Charles M.; Kehm, Karl; Kim, Yoosook; Marti, Kurt

1994-06-01

350

Effect of light, medium and heavy ion irradiations on the structural and electrical properties of ZnSe thin films  

NASA Astrophysics Data System (ADS)

The effect of irradiations of energetic heavy ion beams on the structural and electrical properties of ZnSe thin films deposited on In2O3:Sn (ITO) coated glass substrate is given. The ZnSe thin films having a thickness of 100 nm were deposited by physical vapour deposition on 200 nm thick ITO coated glass. The ZnSe films were irradiated with 20 MeV carbon, phosphorus and copper ion beams using the 5 MV tandem accelerator at National Centre for Physics, Islamabad. The ion irradiations have shown the improvement in the structural properties in terms of increase in grain size and decrease in the lattice strain. The measurements of photo decay have shown that the decay of the photocurrent has been prolonged in the sample irradiated with carbon ion as compared to the phosphorous and copper irradiated sample.

Khurram, A. A.; Jabar, Faisal; Mumtaz, M.; Khan, Nawazish A.; Nasir Mehmood, M.

2013-10-01

351

Structural Modification of Single Wall and Multiwalled Carbon Nanotubes under Carbon, Nickel and Gold Ion Beam Irradiation  

SciTech Connect

Thin film samples of carbon nanotubes were irradiated with ion beam of carbon, nickel and gold. The irradiation results were characterized using Raman Spectroscopy. Modifications of the disorder mode (D mode) and the tangential mode (G mode) under different irradiation fluences were studied in detail. Raman results of carbon ion beam indicate the interesting phenomenon of ordering of the system under irradiation. Under the effect of nickel and gold ion irradiation, the structural evolution of CNTs occurs in three different stages. At lower fluences the process of healing occurs; at intermediate fluences damages on the surface of CNTs occurs and finally at very high fluences of the order of 1x10{sup 14} ions/cm{sup 2} the system gets amorphised.

Jeet, Kiran; Jindal, V. K.; Dharamvir, Keya [Department of Physics, Panjab University, Chandigarh - 160014 (India); Bharadwaj, L. M. [Biomolecular Electronic and Nanotechnology Division, Central Scientific Instruments Organization, Sector 30 -C, Chandigarh - 160030 (India)

2011-12-12

352

Fabrication of ferromagnetic (Ga,Mn)As by ion irradiation  

Microsoft Academic Search

Using Mn+ implantation following ion beam-induced epitaxial crystallization (IBIEC) annealing, high Curie temperature ferromagnetic (Ga,Mn)As thin film was fabricated. The crystalline quality of the Mn+ implanted layer was identified by X-ray diffraction (XRD) and transmission electron microscopy (TEM). A clear ferromagnetic transition at Tc 253K was observed by magnetization vs. temperature measurement. We infer that IBIEC treatment is a useful

C. H. Chen; H. Niu; H. H. Hsieh; C. Y. Cheng; D. C. Yan; C. C. Chi; J. J. Kai; S. C. Wu

2009-01-01

353

Annealing of the defects observed by Raman spectroscopy in UO2 irradiated by 25 MeV He2+ ions  

NASA Astrophysics Data System (ADS)

Understanding the effect of irradiation in UO2 is a major issue for nuclear industry and for the design of irradiation resistant materials. We have previously evidenced irradiation induced defects in UO2 that can be characterized by Raman spectroscopy. Here we present the Raman characterization of these defects as a function of temperature. UO2 samples were irradiated with 25 MeV He2+ ions at room temperature and then heated at different temperature without irradiation. Some samples were also irradiated at high temperature. Heat treatment after irradiation evidenced one annealing temperature on Raman spectra. This annealing temperature is shifted to higher values when the samples are simultaneously heat treated and irradiated. It is compared to the annealing temperatures that are reported in literature on irradiated UO2. This indicates that Raman observed defects would be point defects on uranium sublattice. This attribution is consistent with the one we previously proposed.

Desgranges, L.; Guimbretière, G.; Simon, P.; Duval, F.; Canizares, A.; Omnee, R.; Jégou, C.; Caraballo, R.

2014-05-01

354

The first narrow-band XeCl-excilamp application for complex psoriasis curing  

NASA Astrophysics Data System (ADS)

Clinical efficiency estimation of XeCl-excilamp application for psoriasis curing in comparison with other methods of phototherapy for has been carried out for the first time. Curing psoriasis by XeCl-excilamp assistance is shown to be an effective and present-date method. Such a phototherapy advantages suggested are the good tolerance, and absence of intact skin irradiation. The use of chemicals is no longer relevant, and the total doze of irradiation happens to be rather low.

Dmitruck, Vadim S.; Sosnin, Edward A.; Obgol'tz, Irina A.

2006-05-01

355

Effects of carbon-ion beam irradiation on the angiogenic response in lung adenocarcinoma A549 cells.  

PubMed

Radiotherapy has been focused mainly on killing cancer cells, and little attention has been paid to the process supporting tumor growth and metastasis, including the process of angiogenesis. To investigate the effects of carbon-ion irradiation on angiogenesis in lung cancer cells, we examined the expression of vascular endothelial growth factor and basic fibroblast growth factor in the tumor conditioned medium (TCM) of A549 cells exposed to carbon-ion or X-ray irradiation, as well as endothelial cell growth, invasion, and tube formation induced by TCM. No changes in vascular endothelial growth factor secretion were detected in the TCM of A549 cells exposed to carbon-ion irradiation at 2 or 4?Gy, whereas 1?Gy of irradiation significantly decreased vascular endothelial growth factor and basic fibroblast growth factor levels. Carbon-ion irradiation at 1?Gy inhibited endothelial cell invasion and tube formation. The TCM from A549 cells irradiated with X-ray promoted angiogenesis, whereas the TCM of A549 cells exposed to carbon-ion irradiation at 2 or 4?Gy had no effect. These findings suggest that carbon-ion irradiation at 1?Gy significantly suppressed the process of angiogenesis in vitro by inhibiting endothelial cell invasion and tube formation, which are related to vascular endothelial growth factor and basic fibroblast growth factor production. PMID:24942319

Liu, Yuanyuan; Liu, Yang; Zhang, Hong; Sun, Chao; Zhao, Qiuyue; Di, Cixia; Li, Hongyan; Gan, Lu; Wang, Yali

2014-11-01

356

Influence of Ar, Ne, Xe, and CCl4 impurities on luminescence kinetics of Cd II ions (5 s 2 2 D 5/2-5 p 2 P 3/2 transition, ? = 441.6 nm) in He-Cd mixture  

NASA Astrophysics Data System (ADS)

The luminescence kinetics of the Cd II ion at a wavelength of 441.6 nm has been studied experi-mentally in a high-pressure He-Cd mixture in the presence of Ar, Ne, Xe, and CCl4 impurities. Cadmium ions were excited through the bombardment of a cadmium foil heated up to 240°C by a pulsed electron beam with an electron energy of 150 keV, a pulse duration of 3 ns, and a current of 500 A. The constants of collisional quenching of the Cd II 5 s 2 2 D 5/2 level by Ar, Ne, and Xe atoms and CCl4 molecules and the integral luminescence quenching constants of this level in the helium medium by these impurity gases have been determined. The constants of collisional quenching appeared to be 8.1 × 10-12 (Ar), 1.2 × 10-12 (Xe), 1.5 × 10-13 (Ne), and 1.8 × 10-10 cm3/s (CCl4, for ? = 325 nm), while the integral constants were found to be, respectively, 4.1 × 10-11, 3.4 × 10-11, 9.5 × 10-12, 1.4 × 10-9 cm3/s for Ar, Ne, Xe, and CCl4 at a buffer gas pressure of 1 atm.

Miskevich, A. I.; Liu, Tao

2009-07-01

357

Effects of high energy Au-ion irradiation on the microstructure of diamond films  

SciTech Connect

The effects of 2.245 GeV Au-ion irradiation and subsequent annealing processes on the evolution of microstructure of diamond films with microcrystalline (MCD) or ultra-nanocrystalline (UNCD) granular structure were investigated, using near edge x-ray absorption fine structure and electron energy loss spectroscopy in transmission electron microscopy. For MCD films, the Au-ion irradiation disintegrated some of the diamond grains, resulting in the formation of nano-sized carbon clusters embedded in a matrix of amorphous carbon (a-C). The annealing process recrystallized the diamond grains and converted the a-C into nano-sized graphite particulates and, at the same time, induced the formation of nano-sized i-carbon clusters, the bcc structured carbon with a{sub 0} = 0.432 nm. In contrast, for UNCD films, the Au-ion irradiation transformed the grain boundary phase into nano-sized graphite, but insignificantly altered the crystallinity of the grains of the UNCD films. The annealing process recrystallized the materials. In some of the regions, the residual a-C phases were transformed into nano-sized graphites, whereas in other regions i-carbon nanoclusters were formed. The difference in irradiation-induced microstructural transformation behavior between the MCD and the UNCD films is ascribed to the different granular structures of the two types of films.

Chen, Shih-Show [Department of Physics, Tamkang University, Tamsui, New-Taipei 251, Taiwan (China); Department of Information Technology and Mobile Communication, Taipei College of Maritime Technology, Tamsui, New-Taipei 251, Taiwan (China); Chen, Huang-Chin [Department of Physics, Tamkang University, Tamsui, New-Taipei 251, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Wang, Wei-Cheng; Lin, I-Nan; Chang, Ching-Lin [Department of Physics, Tamkang University, Tamsui, New-Taipei 251, Taiwan (China); Lee, Chi-Young [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Guo Jinghua [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2013-03-21

358

Spectroscopic and TSDC analysis of 100 MeV Ag ion irradiated polyetherimide  

NASA Astrophysics Data System (ADS)

The energetic heavy ion irradiation effects in polymers have drawn considerable attention for the application of polymers in radioactive environment. In the present paper, we report the Fourier transform infrared (FTIR) and UV-visible spectroscopic analysis and thermally stimulated depolarization current (TSDC) investigations in polyetherimide (PEI) samples (25 ?m) irradiated with 100 MeV Ag ion at different fluences (5.6×1010, 1.8×1011, 1.8×1012 ions/cm2). The FTIR spectra of irradiated samples show an overall decrease in the intensity of all the typical bands, whereas the UV-visible spectra show a hyperchromic and bathochromic shift attributed to the formation of new defect sites. The radiation induced dehydrogenation of the methyl pendent group, opening of imide rings and the formation of carbonyl radicals and unsaturated C = C bonds are the major conclusion drawn from the FTIR analysisE The TSDC spectra of pristine PEI comprises two current maxima termed as ?- and ?-peak with their respective locations around 80° and 190 °C. These are attributed to dipole-orientation and space charge relaxation, respectively. A significant effect of irradiation is observed on the whole TSDC spectrum. The ?-peak vanishes due to demerization of carbonyl groups. Enhancement in the ?-peak has been associated to the formation of new deep traps. Some new radiation induced relaxation processes have also been identified.

Goyal, Geetika; Garg, Maneesha; Quamara, J. K.

359

Investigation of hydrogen concentration and hardness of ion irradiated organically modified silicate thin films  

NASA Astrophysics Data System (ADS)

A study of the effects of ion irradiation of organically modified silicate thin films on the loss of hydrogen and increase in hardness is presented. NaOH catalyzed SiNa wO xC yH z thin films were synthesized by sol-gel processing from tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) precursors and spin-coated onto Si substrates. After drying at 300 °C, the films were irradiated with 125 keV H + or 250 keV N 2+ at fluences ranging from 1 × 10 14 to 2.5 × 10 16 ions/cm 2. Elastic Recoil Detection (ERD) was used to investigate resulting hydrogen concentration as a function of ion fluence and irradiating species. Nanoindentation was used to measure the hardness of the irradiated films. FT-IR spectroscopy was also used to examine resulting changes in chemical bonding. The resulting hydrogen loss and increase in hardness are compared to similarly processed acid catalyzed silicate thin films.

Qi, Y.; Prenzel, T.; Harriman, T. A.; Wang, Y. Q.; Lucca, D. A.; Williams, D.; Nastasi, M.; Dong, J.; Mehner, A.

2010-06-01

360

XeCl laser treatment of polyethersulfone membrane in the air and water  

NASA Astrophysics Data System (ADS)

XeCl laser irradiation of Polyethersulfone membranes in air and water were done. The irradiated surface were modified chemically or morphologically depends on the laser parameters and the mediums in which irradiation is done. The results in improving the surface hydrophilicity and biocompatibility for the biological applications were compared.

Hashemi Panah, A.; Pazokian, H.; Mollabashi, M.; Barzin, J.

2015-03-01

361

Formation of complex precursors of amino acids by irradiation of simulated interstellar media with heavy ions  

NASA Astrophysics Data System (ADS)

A wide variety of organic compounds have been detected in such extraterrestrial bodies as meteorites and comets Amino acids were identified in the extracts from Murchison meteorite and other carbonaceous chondrites It is hypothesized that these compounds are originally formed in ice mantles of interstellar dusts ISDs in molecular clouds by cosmic rays and ultraviolet light UV Formation of amino acid precursors by high energy protons or UV irradiation of simulated ISDs was reported by several groups The amino acid precursors were however not well-characterized We irradiated a frozen mixture of methanol ammonia and water with heavy ions to study possible organic compounds abiotically formed in molecular clouds by cosmic rays A mixture of methanol ammonia and water was irradiated with carbon beams 290 MeV u from a heavy ion accelerator HIMAC of National Institute of Radiological Sciences Japan Irradiation was performed either at room temperature liquid phase or at 77 K solid phase The products were characterized by gel filtration chromatography GFC FT-IR pyrolysis PY -GC MS etc Amino acids were analyzed by HPLC and GC MS after acid hydrolysis or the products Amino acids such as glycine and alanine were identified in the products in both the cases of liquid phase and solid phase irradiation Energy yields G-values of glycine were 0 014 liquid phase and 0 007 solid phase respectively Average molecular weights of the products were estimated as to 2300 in both the case Aromatic hydrocarbons N-containing heterocyclic

Kobayashi, K.; Suzuki, N.; Taniuchi, T.; Kaneko, T.; Yoshida, S.

362

Microstructure evolution and hardness change in ordered Ni3V intermetallic alloy by energetic ion irradiation  

NASA Astrophysics Data System (ADS)

Ni3V bulk intermetallic compounds with ordered D022 structure were irradiated with 16 MeV Au ions at room temperature. The irradiation induced phase transformation was examined by means of the transmission electron microscope (TEM), the extended X-ray absorption fine structure measurement (EXAFS) and the X-ray diffraction (XRD). We also measured the Vickers hardness for unirradiated and irradiated specimens. The TEM observation shows that by the Au irradiation, the lamellar microstructures and the super lattice spot in diffraction pattern for the unirradiated specimen disappeared. This TEM result as well as the result of XRD and EXAFS measurements means that the intrinsic D022 structure of Ni3V changes into the A1 (fcc) structure which is the lattice structure just below the melting point in the thermal equilibrium phase diagram. The lattice structure change from D022 to A1 (fcc) accompanies a remarkable decrease in Vickers microhardness. The change in crystal structure was discussed in terms of the thermal spike and the sequential atomic displacements induced by the energetic heavy ion irradiation.

Hashimoto, A.; Kaneno, Y.; Semboshi, S.; Yoshizaki, H.; Saitoh, Y.; Okamoto, Y.; Iwase, A.

2014-11-01

363

Microstructure and Mechanical Properties of Ti3SiC2 Irradiated by Carbon Ions  

NASA Astrophysics Data System (ADS)

Thanks to its noteworthy mechanical properties, excellent damage tolerance and good thermal stability, the Ti3SiC2 ternary compound has attracted great concern and has been considered as a potential structural component material for the 4th generation of reactors (e.g., gas fast nuclear reactors) and future fusion reactors. The outstanding properties are due to the nanolamellar structure which imparts characteristics of both metals and ceramics to this material. In our work, Ti3SiC2 samples have been irradiated by C+ ions with a high fluence of 1.78 × 1017 ions/cm2 at a range of temperatures from 120°C-850°C. Subsequently, series of characterization techniques including synchrotron irradiation x-ray diffraction, scanning electron microscopy and nano-indentation are carried out to understand the changes of microstructure and mechanical properties. The composition exhibits high damage tolerant properties and a high recovery rate through the analysis, especially at high temperature. The minimum damage to an irradiated sample appears around 350°C in the temperature range 120°C-550°C. At a high irradiation temperature, a significant reduction in the damage can be achieved and an almost complete lack of damage compared with an un-irradiated sample is revealed at the temperature of 850°C.

Wang, Kun; Qi, Qiang; Cheng, Gui-Jun; Shi, Li-Qun

2014-07-01

364

Morphologic and morphometric analysis of the early effects of x-ray and heavy-ion irradiation of hamster lung.  

PubMed Central

Morphometric methods were to used to compare the early effects of graded single doses of x-rays with accelerated heavy particle (helium or neon) irradiation of hamster lung. Increased values in the volume densities of both capillary lumina and inflammatory cells at 2 weeks postirradiation were observed. Neon-ion irradiation wes statisically different from x-irradiation at all dose levels, while helium-ion irradiation showed significant increases only at higher doses (1000 to 1500 rads). At 1 month post-irradiation, the volume densities of capillary lumina after heavy particle irradiation began to return to control values, while those in x=irradiated lungs continued to be elevated. The volume density of inflammatory cells remained increased for all types of irradiation, and the highest values were obtained in neon-ion irradiated lungs. Accelerated heavy particle irradiation would therefore appear to elicit a more intense early radiation than does x-irradiation but the chronic significance of these findings is not yet known. Images Figure 2 Figure 1 PMID:1251887

Woodruff, K. H.; Leith, J. T.; Lyman, J. T.; Tobias, C. A.

1976-01-01

365

Ion irradiation induced Al-Ti interaction in nano-scaled Al/Ti multilayers  

NASA Astrophysics Data System (ADS)

Interactions induced in Al/Ti multilayers by implantation of Ar ions at room temperature were investgated. Initial structures consisted of (Al/Ti) × 5 multilayers deposited by d.c. ion sputtering on Si(1 0 0) wafers, to a total thickness of ?250 nm. They were irradiated with 200 keV Ar+ ions, to the fluences from 5 × 1015 to 4 × 1016 ions/cm2. It was found that ion irradiation induced a progressed intermixing of the multilayer constituents and Al-Ti nanoalloying for the highest applied fluence. The resulting nanocrystalline structure had a graded composition with non-reacted or interdiffused Al and Ti, and ?-AlTi and AlTi3 intermetallic phases. Most intense reactivity was observed around mid depth of the multilayers, where most energy was deposited by the impact ions. It is presumed that Al-Ti chemical reaction is triggered by thermal spikes and further enhanced by chemical driving forces. The applied processing can be interesting for fabrication of tightly bond multilayered structures with gradual changes of their composition and properties.

Milosavljevi?, M.; Stojanovi?, N.; Peruško, D.; Timotijevi?, B.; Toprek, D.; Kova?, J.; Draži?, G.; Jeynes, C.

2012-01-01

366

On the relative importance of physical and chemical sputtering during ion-enhanced etching of silicon by XeF2  

Microsoft Academic Search

Product translational energy distributions have been used in previous studies as a diagnostic of surface reaction enhancement mechanisms under ion bombardment. Haring and co-workers [R. A. Haring, A. Haring, F. W. Saris, and A. E. de Vries, Appl. Phys. Lett. 41, 174 (1982)] have taken an E?2 dependence for SiFx species desorbing during ion-enhanced etching of silicon as evidence for

F. A. Houle

1987-01-01

367

Experimental measurement methods and data on irradiation of functional design materials by helium ions in linear accelerator  

E-print Network

The experimental research on the irradiation of the functional design materials by the Helium ions in the linear accelerator is conducted. The experimental measurements techniques and data on the irradiation of the functional design materials by the Helium ions with the energy up to 4 MeV, including the detailed scheme of experimental measurements setup, are presented. The new design of accelerating structure of the IH-type such as POS-4, using the method of alternate-phase focusing with the step-by-step change of the synchronous phase along the focusing periods in a linear accelerator, is developed with the aim to irradiate the functional design materials by the Helium ions. The new design of the injector of the charged Helium ions with the energy of 120 KeV at the output of an accelerating tube and the accelerating structure of the type of POS-4 for the one time charged Helium ions acceleration in the linear accelerator are researched and developed. The special chamber for the irradiation of functional design materials by the Helium ions is also created. In the process of experiment, the temperature of a sample, the magnitude of current of Helium ions beam and the irradiation dose of sample are measured precisely. The experimental measurement setup and techniques are fully tested and optimized in the course of the research on the electro-physical properties of irradiated samples and the thermal-desorption of Helium ions in a wide range of temperatures

R. A. Anokhin; V. N. Voyevodin; S. N. Dubnyuk; A. M. Egorov; B. V. Zaitsev; A. F. Kobets; O. P. Ledenyov; K. V. Pavliy; V. V. Ruzhitsky; G. D. Tolstolutskaya

2013-09-03

368

Effects of additives on cordycepin production using a Cordyceps militaris mutant induced by ion beam irradiation  

Microsoft Academic Search

To obtain a sustainable mutant of the medicinal mushroom Cordyceps militaris with a higher cordycepin production, high-energy ion beam irradiation was applied in the present study. Upon successful irradiation by a proton beam, 30 classes of 8-azaadenine and 28 classes of 8-azaaguanine resistant mutants were obtained of which 7 classes (A63-7, A63-8, A81-2, A81-6, G63-8, G81-3, G82-4) were selected as

S. K. Das; M. Masuda; A. Sakurai; M. Sakakibara

369

Synthesis, characterization and effect of low energy Ar ion irradiation on gadolinium oxide nanoparticles  

SciTech Connect

Graphical abstract: . The figure depicts Raman spectra of (A) unirradiated and (B) 80 keV Ar ion irradiated nanoscale gadolinium oxide (Gd{sub 2}O{sub 3}) systems. Intense Raman signals corresponding to two B{sub g} modes at 288 and 384 cm{sup -1} are observed for irradiated sample along with the evolution of a new peak at 202 cm{sup -1} due to surface defects. Highlights: {yields} Gadolinium oxide nanoparticles are synthesized via a selective reduction route. {yields} 80 keV Ar ion-irradiated specimen showed better symmetric emission than pristine. {yields} Irradiation led point defect contribution was studied through spectroscopic means. -- Abstract: In this work, we report on the surfactant assisted synthesis of gadolinium oxide (Gd{sub 2}O{sub 3}) nanoparticles and their characterization through various microscopic and spectroscopic tools. Exhibiting a monoclinic phase, the nanoscale Gd{sub 2}O{sub 3} particles are believed to be comprising of crystallites with an average size of {approx}3.2 nm, as revealed from the X-ray diffraction analysis. The transmission electron microscopy has predicted a particle size of {approx}9 nm and an interplanar spacing of {approx}0.28 nm. Fourier transform infrared spectroscopy studies show that Gd-O inplane vibrations at 536.8 and 413.3 cm{sup -1} were more prominent for 80-keV Ar-ion irradiated Gd{sub 2}O{sub 3} nanosystem than unirradiated system. The photoluminescence (PL) spectra of irradiated specimen have revealed an improvement in the symmetry factor owing to significant enhancement of surface-trap emission, compared to the band-edge counterpart. Irradiation induced creation of point defects (oxygen vacancies) were predicted both from PL and electron paramagnetic resonance (EPR) studies. Further, the Raman spectra of the irradiated sample have exhibited notable vibrational features along with the evolution of a new peak at {approx}202 cm{sup -1}. This can be ascribed to an additional Raman active vibrational response owing to considerable modification of the nanostructure surface as a result of ion bombardment. Probing nanoscale defects through prime spectroscopy tools would find a new avenue for precise tuning of physical properties with generation and annihilation of defects.

Paul, N.; Devi, M. [Nanoscience Laboratory, Department of Physics, Tezpur University, Assam, 784028 (India)] [Nanoscience Laboratory, Department of Physics, Tezpur University, Assam, 784028 (India); Mohanta, D., E-mail: best@tezu.ernet.in [Nanoscience Laboratory, Department of Physics, Tezpur University, Assam, 784028 (India)

2011-08-15

370

Effect of chemical etching on poly(methyl methacrylate) irradiated with slow highly charged ions  

NASA Astrophysics Data System (ADS)

We have recently demonstrated that individual slow highly charged ions are able to produce nano-sized pits on poly(methyl methacrylate) surfaces as a result of direct ablation due to the deposition of their high potential energy, if this energy exceeds a critical minimum value. By exposing irradiated samples to a suitable etchant, such pits can be revealed even below this potential energy threshold as latent damage zones are removed. Existing pits grow both in diameter and in depth after contact with the etchant with different etching dynamics for both dimensions. Systematic studies on the response of irradiated samples to a chemical developer are presented.

Ritter, Robert; Wilhelm, Richard A.; Ginzel, Rainer; Schadauer, Philip; Heller, René; Rupp, Werner; Crespo López-Urrutia, José R.; Facsko, Stefan; Aumayr, Friedrich

2013-09-01

371

Microarray Analysis of Human Liver Cells irradiated by 80MeV/u Carbon Ions  

NASA Astrophysics Data System (ADS)

Objective Biological effect of heavy ion beam has the important significance for cancer therapy and space exploring owing its high LET and RBE, low OER, especially forming Bragg spike at the end of the tracks of charged particles. More serious damage for cells are induced by heavy ions and difficult repair than other irradiation such as X-ray and ?-ray . To explore the molecular mechanism of biological effect caused by heavy ionizing radiation (HIR) and to construct the gene expression profile database of HIR-induced human liver cells L02 by microarray analysis. Methods In this study, L02 cells were irradiated by 80MeV/u carbon ions at 5 Gy delivered by HIRFL (Heavy Ion Research Facility in Lanzhou) at room temperature. Total RNAs of cells incubated 6 hours and 24hours after irradiation were extracted with Trizol. Unirradiated cells were used as a control. RNAs were transcripted into cDNA by reverse transcription and labelled with cy5-dCTP and cy3-dCTP respectively. A human genome oligonucleotide set consisting of 5 amino acid-modified 70-mer probes and representing 21,329 well-characterized Homo sapiens genes was selected for microarray analysis and printed on amino-silaned glass slides. Arrays were fabricated using an OmniGrid microarrayer. Only genes whose alteration tendency was consistent in both microarrays were selected as differentially expressed genes. The Affymetrix's short oligonucleotide (25-mer) HG U133A 2.0 array analyses were performed per the manufacturer's instructions. Results Of the 21,329 genes tested, 37 genes showed changes in expression level with ratio higher than 2.0 and lower than 0.5 at 6hrs after irradiation. There were 19 genes showing up-regulation in radiated L02 cells, whereas 18 genes showing down-regulation; At 24hrs after irradiation, 269 genes showed changes in expression level with ratio higher than 2.0 and lower than 0.5. There were 67 genes showing up-regulation in radiated L02 cells, whereas 202 genes showing down-regulation. Furthermore 3 genes, ATP5G2, NFKBIE, RELB all showed up-regulation with ratio high than 2 at 6h and 24h after irradiation. Conclusion There are different gene expressions in L02 cells at 6h and 24h after irradiated by 5Gy carbon ions. The genes are mainly involved in DNA damage, cell cycle apoptosis, immune response and signal transduction in L02 cells. These results provide deeper insight into the mechanism of gene damage and repair after HIR.

Wang, Xiao; Tian, Xiaoling; Kong, Fuquan; Li, Qiang; Jin, Xiaodong; Dai, Zhongying; Zhang, Hong; Yang, Mingjian; Zhao, Kui

372

Characterization of thermal conductivity degradation induced by heavy ion irradiation in ceramic materials  

NASA Astrophysics Data System (ADS)

Thermal conductivity degradation of three semi-metallic ceramics: titanium carbide, zirconium carbide and titanium nitride, and a covalent compound: 6H silicon carbide, induced by irradiation with energetic heavy ions at room temperature, is studied and quantified. Irradiations by 25.8 MeV krypton ions at 1016 and 6 × 1016 ions cm-2 doses were used to produce defects in the considered materials. Modulated thermoreflectance microscopy measurements were performed to characterize the resulting subsurfasic degradation of the thermal conductivity for each of the investigated materials. The study considers the two collision domains produced by the inelastic collisions and the elastic collisions that occur during an ion irradiation. A significant thermal conductivity degradation in the two collision domains for all materials is obtained. Elastic collisions are shown to degrade the thermal properties more strongly than the inelastic ones. The scattering of thermal energy carriers is larger in the elastic collision domain because displacement cascades produce a very high concentration of point defects. The degradation coming from electronic interactions is found to be more important in SiC, which can be explained by the presence of large populations of generated extended defects, facing generated individual point defects in the studied semi-metallic materials.

David, L.; Gomès, S.; Carlot, G.; Roger, J.-P.; Fournier, D.; Valot, C.; Raynaud, M.

2008-02-01

373

Ag clustering investigation in laser irradiated ion-exchanged glasses by optical and vibrational spectroscopy  

NASA Astrophysics Data System (ADS)

Ion exchange process is widely used to dope silicate glass layers with silver for several applications, ranging from light waveguide to nanostructured composite glass fabrication. The silver-doped structure and its physical properties depend on the preparation parameters as well as on subsequent treatments. In particular, laser irradiation of the ion exchanged glasses has been demonstrated to be an effective tool to control cluster size and size distribution. Nevertheless, a complete comprehension of the basic phenomena and a systematic characterization of these systems are still lacking. In this paper, an extended optical characterization is presented for soda-lime glass slides, doped with silver by Ag+-Na+ ion exchange, thermally treated and irradiated with a Nd:YAG laser beam at different wavelengths, and for different energy density. The samples were characterized by various spectroscopic techniques, namely, optical absorption, photoluminescence and micro-Raman analysis. The availability of all these characterization techniques allowed pointing out a suitable scenario for the Ag clustering evolution as a function of the ion exchange, annealing and laser irradiation parameters.

Trave, E.; Cattaruzza, E.; Gonella, F.; Calvelli, P.; Quaranta, A.; Rahman, A.; Mariotto, G.

2012-09-01

374

Effect of ion flux on helium retention in helium-irradiated tungsten  

NASA Astrophysics Data System (ADS)

Helium retention in irradiated tungsten leads to swelling, pore formation, sample exfoliation and embrittlement with deleterious consequences in many applications. In particular, the use of tungsten in future nuclear fusion plants is proposed due to its good refractory properties. However, serious concerns about tungsten survivability stems from the fact that it must withstand severe irradiation conditions. In magnetic fusion as well as in inertial fusion (particularly with direct drive targets), tungsten components will be exposed to low and high energy ion irradiation (helium), respectively. A common feature is that the most detrimental situations will take place in pulsed mode, i.e., high flux irradiation. There is increasing evidence of a correlation between a high helium flux and an enhancement of detrimental effects on tungsten. Nevertheless, the nature of these effects is not well understood due to the subtleties imposed by the exact temperature profile evolution, ion energy, pulse duration, existence of impurities and simultaneous irradiation with other species. Object Kinetic Monte Carlo is the technique of choice to simulate the evolution of radiation-induced damage inside solids in large temporal and space scales. We have used the recently developed code MMonCa (Modular Monte Carlo simulator), presented at COSIRES 2012 for the first time, to study He retention (and in general defect evolution) in tungsten samples irradiated with high intensity helium pulses. The code simulates the interactions among a large variety of defects and during the irradiation stage and the subsequent annealing steps. The results show that the pulsed mode leads to significantly higher He retention at temperatures higher than 700 K. In this paper we discuss the process of He retention in terms of trap evolution. In addition, we discuss the implications of these findings for inertial fusion.

Rivera, A.; Valles, G.; Caturla, M. J.; Martin-Bragado, I.

2013-05-01

375

Heavy-Ion Irradiation of Thulium(III) Oxide Targets Prepared by Polymer-Assisted Deposition  

SciTech Connect

Thulium(III) oxide (Tm{sub 2}O{sub 3}) targets prepared by the polymer-assisted deposition (PAD) method were irradiated by heavy-ion beams to test the method's feasibility for nuclear science applications. Targets were prepared on silicon nitride backings (thickness of 1000 nm, 344 {micro}g/cm{sup 2}) and were irradiated with an {sup 40}Ar beam at laboratory frame energy of {approx}210 MeV (50 particle nA). The root mean squared (RMS) roughness prior to irradiation is 1.1 nm for a {approx}250 nm ({approx}220 {micro}g/cm{sup 2}) Tm{sub 2}O{sub 3} target, and an RMS roughness of 2.0 nm after irradiation was measured by atomic force microscopy (AFM). Scanning electron microscopy of the irradiated target reveals no significant differences in surface homogeneity when compared to imaging prior to irradiation. Target flaking was not observed from monitoring Rutherford scattered particles as a function of time.

Garcia, Mitch A.; Ali, Mazhar N.; Chang, Noel N.; Parsons-Moss, Tashi; Ashby, Paul D.; Gates, Jacklyn M.; Stavsetra, Liv; Gregorich, Kenneth E.; Nitsche, Heino

2008-09-15

376

Irradiation With Carbon Ion Beams Induces Apoptosis, Autophagy, and Cellular Senescence in a Human Glioma-Derived Cell Line  

SciTech Connect

Purpose: We examined biological responses of human glioma cells to irradiation with carbon ion beams (C-ions). Methods and Materials: A human glioma-derived cell line, NP-2, was irradiated with C-ions. Apoptotic cell nuclei were stained with Hoechst 33342. Induction of autophagy was examined either by staining cells with monodansylcadaverine (MDC) or by Western blotting to detect conversion of microtuble-associated protein light chain 3 (MAP-LC3) (LC3-I) to the membrane-bound form (LC3-II). Cellular senescence markers including induction of senescence-associated beta-galactosidase (SA-beta-gal) were examined. The mean telomere length of irradiated cells was determined by Southern blot hybridization. Expression of tumor suppressor p53 and cyclin/cyclin-dependent kinase inhibitor p21{sup WAF1/CIP1} in the irradiated cells was analyzed by Western blotting. Results: When NP-2 cells were irradiated with C-ions at 6 Gy, the major population of the cells died of apoptosis and autophagy. The residual fraction of attached cells (<1% of initially irradiated cells) could not form a colony: however, they showed a morphological phenotype consistent with cellular senescence, that is, enlarged and flattened appearance. The senescent nature of these attached cells was further indicated by staining for SA-beta-gal. The mean telomere length was not changed after irradiation with C-ions. Phosphorylation of p53 at serine 15 as well as the expression of p21{sup WAF1/CIP1} was induced in NP-2 cells after irradiation. Furthermore, we found that irradiation with C-ions induced cellular senescence in a human glioma cell line lacking functional p53. Conclusions: Irradiation with C-ions induced apoptosis, autophagy, and cellular senescence in human glioma cells.

Jinno-Oue, Atsushi; Shimizu, Nobuaki [Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); 21st Century Center of Excellence Program for Biomedical Research Using Accelerator Technology, Maebashi, Gunma (Japan); Hamada, Nobuyuki; Wada, Seiichi [21st Century Center of Excellence Program for Biomedical Research Using Accelerator Technology, Maebashi, Gunma (Japan); Microbeam Radiation Biology Group, Radiation-Applied Biology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Takasaki, Gunma (Japan); Department of Quantum Biology, Division of Bioregulatory Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Tanaka, Atsushi; Shinagawa, Masahiko; Ohtsuki, Takahiro; Mori, Takahisa; Saha, Manujendra N.; Hoque, Ariful S.; Islam, Salequl [Department of Virology and Preventive Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); 21st Century Center of Excellence Program for Biomedical Research Using Accelerator Technology, Maebashi, Gunma (Japan); Kogure, Kimitaka [Department of General Surgical Science, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Funayama, Tomoo [Microbeam Radiation Biology Group, Radiation-Applied Biology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Takasaki, Gunma (Japan); Kobayashi, Yasuhiko [21st Century Center of Excellence Program for Biomedical Research Using Accelerator Technology, Maebashi, Gunma (Japan); Microbeam Radiation Biology Group, Radiation-Applied Biology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, Takasaki, Gunma (Japan); Department of Quantum Biology, Division of Bioregulatory Medicine, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan)

2010-01-15

377

Mass and double-beta-decay Q value of 136Xe.  

PubMed

The atomic mass of 136Xe has been measured by comparing cyclotron frequencies of single ions in a Penning trap. The result, with 1 standard deviation uncertainty, is M(136Xe)=135.907 214 484 (11) u. Combined with previous results for the mass of 136Ba [Audi, Wapstra, and Thibault, Nucl. Phys. A 729, 337 (2003)10.1016/j.nuclphysa.2003.11.003], this gives a Q value (M[136Xe]-M[136Ba])c(2)=2457.83(37) keV, sufficiently precise for ongoing searches for the neutrinoless double-beta decay of 136Xe. PMID:17358854

Redshaw, Matthew; Wingfield, Elizabeth; McDaniel, Joseph; Myers, Edmund G

2007-02-01

378

Hyperpolarized 131Xe NMR spectroscopy  

PubMed Central

Hyperpolarized (hp) 131Xe with up to 2.2% spin polarization (i.e., 5000-fold signal enhancement at 9.4 T) was obtained after separation from the rubidium vapor of the spin-exchange optical pumping (SEOP) process. The SEOP was applied for several minutes in a stopped-flow mode, and the fast, quadrupolar-driven T1 relaxation of this spin I = 3/2 noble gas isotope required a rapid subsequent rubidium removal and swift transfer into the high magnetic field region for NMR detection. Because of the xenon density dependent 131Xe quadrupolar relaxation in the gas phase, the SEOP polarization build-up exhibits an even more pronounced dependence on xenon partial pressure than that observed in 129Xe SEOP. 131Xe is the only stable noble gas isotope with a positive gyromagnetic ratio and shows therefore a different relative phase between hp signal and thermal signal compared to all other noble gases. The gas phase 131Xe NMR spectrum displays a surface and magnetic field dependent quadrupolar splitting that was found to have additional gas pressure and gas composition dependence. The splitting was reduced by the presence of water vapor that presumably influences xenon-surface interactions. The hp 131Xe spectrum shows differential line broadening, suggesting the presence of strong adsorption sites. Beyond hp 131Xe NMR spectroscopy studies, a general equation for the high temperature, thermal spin polarization, P, for spin I?1/2 nuclei is presented. PMID:21051249

Stupic, Karl F.; Cleveland, Zackary I.; Pavlovskaya, Galina E.; Meersmann, Thomas

2011-01-01

379

From holes to sponge at irradiated Ge surfaces with increasing ion energy—an effect of defect kinetics?  

NASA Astrophysics Data System (ADS)

We show that hole patterns and sponge-like layers at irradiated Ge surfaces originate from the same driving force, namely the kinetics of ion beam induced defects in the amorphous Ge surface layer. Ge hole patterns reported earlier for irradiation with low energy (5 keV) Ga+ ions were reproduced for low energy Bi+ but also for Ge+ self-irradiation, which proves that the dominating driving force for morphology evolution cannot originate from the implanted impurities. At higher ion energies the well-known formation of sponge-like Ge surface layers after heavy ion irradiation was found for Bi+ irradiation and Ge+ self-irradiation, also. The transition from smooth surfaces via hole patterns to sponge-like morphologies with increasing ion energies was studied in detail. A model based on the kinetics of ion beam induced defects was developed and implemented in 3D kinetic Monte Carlo simulations, which reproduce the transition from hole patterns to sponge-like layers with increasing ion energy.

Böttger, Roman; Heinig, Karl-Heinz; Bischoff, Lothar; Liedke, Bartosz; Facsko, Stefan

2013-10-01

380

Effect of Proton and Silicon Ion Irradiation on Defect Formation in GaAs  

SciTech Connect

Electrical and structural changes in GaAs are monitored using electron beam induced current (EBIC) and transmission electron microscopy (TEM) measurements after irradiation by protons and silicon ions. It has been determined that higher energy protons (E ges 10 MeV) and silicon ions disordered regions that are electrically and structurally different than those produced by lower energy protons. The data suggest that these disordered regions are responsible for causing the deviations between experimental data and NIEL. From analyses of the recoil spectra, high energy recoils appear to be responsible for the formation of these disordered regions.

Warner, J. H.; Inguimbert, C.; Twigg, M. E.; Messenger, S. R.; Walters, R. J.; Romero, M. J.; SUmmers, G. P.

2008-12-01

381

Stress-induced patterns in ion-irradiated Silicon: a model based on anisotropic plastic flow  

E-print Network

We present a model for the effect of stress on thin amorphous films that develop atop ion-irradiated silicon, based on the mechanism of ion-induced anisotropic plastic flow. Using only parameters directly measured or known to high accuracy, the model exhibits remarkably good agreement with the wavelengths of experimentally-observed patterns, and agrees qualitatively with limited data on ripple propagation speed. The predictions of the model are discussed in the context of other mechanisms recently theorized to explain the wavelengths, including extensive comparison with an alternate model of stress.

Scott A. Norris

2012-07-24

382

Temporal stability of Y Ba Cu O nano Josephson junctions from ion irradiation  

SciTech Connect

We investigate the temporal stability of YBa2Cu3O7 Josephson junctions created by ion irradiation through a nano-scale implant mask fabricated using electron beam lithography and reactive ion etching. A comparison of current-voltage characteristics measured for junctions after fabrication and eight years of storage at room temperature show a slight decrease in critical current and increase in normal state resistance consistent with broadening of the weaklink from diffusion of defects. Shapiro step measurements performed 8 years after fabrication reveal that device uniformity is maintained and is strong evidence that these devices have excellent temporal stability for applications.

Cybart, Shane A.; Roediger, Peter; Chen, Ke; Parker, J. M.; Cho, Ethan Y.; Wong, Travis J.; Dynes, R. C.

2012-11-29

383

Increasing the Stiffness of SWCNT Bucky Paper by Heavy Ion Irradiation  

NASA Astrophysics Data System (ADS)

We verify simulation results indicating that carbon ion irradiation increases the stiffness of single wall carbon nanotube bucky paper (SWCNT). 4 MHz longitudinal and 15 MHz shear ultrasonic signals were transmitted by means of dry-coupled acoustic horns through 40±4 ?m thick samples and the time-of-flight (TOF) through the samples was measured. From the TOF the velocity of the wave was determined and the out-of-plane elastic and shear moduli were calculated. The nonlinearity parameter B/A for the irradiated and reference sample was measured. The results indicated a significant increase both in the shear modulus (90 %) and in the longitudinal modulus (69 %) for certain irradiation doses as predicted by simulations. In addition, a 36% increase in the acoustic nonlinearity parameter (B/A) was observed. The investigated fluence range was 1?1013 to 3?1014 cm-2.

Salmi, Ari; Hæggström, Edward; Arstila, Kai; Nordlund, Kai; Keinonen, Juhani

2007-03-01

384

Postmortem examination of 22 pancreatic carcinoma patients treated with helium ion irradiation  

SciTech Connect

Postmortem findings are available in this report in 22 patients with pancreatic carcinoma treated with helium ions at Lawrence Berkeley Laboratory; California. This represents the largest group evaluated histologically in the literature and is the first report evaluating effects of particle radiation in pancreatic tissue. Patient survival after therapy averaged 9 months. Most died of infection and/or pulmonary emboli. Local control was achieved in 27%. The pancreatic tumors had histologically more severe radiation changes than nontumor bearing pancreas. Irradiated bone marrow was severely hypocellular, and irradiated skin was atrophic. Five patients had radiation injury in the gastrointestinal tract. The spinal cord, liver, and kidneys showed no damage. This study demonstrates the safety of helium particle irradiation with present therapeutic planning. Injury to tumor was seen without excessive damage to adjacent tissues.

Woodruff, K.H.; Castro, J.R.; Quivey, J.M.; Saunders, W.M.; Chen, G.T.; Lyman, J.T.; Pitluck, S.; Tobias, C.A.; Walton, R.E.; Peters, T.C.

1984-02-01

385

Nano suboxide layer generated in Ta2O5 by Ar+ ion irradiation  

NASA Astrophysics Data System (ADS)

Ta2O5/TaOx heterostructure has become a leading oxide layer in memory cells and/or a bidirectional selector for resistive random access memory (RRAM). Although atomic layer deposition (ALD) was found to be uniquely suitable for depositing uniform and conformal films on complex topographies, it is hard to use ALD to grow suboxide TaOx layer. In this study, tantalum oxide films with a composition of Ta2O5 were grown by ALD. Using Ar+ ion irradiation, the suboxide was formed in the top layer of Ta2O5 films by observing the Ta core level shift toward lower binding energy with angle-resolved X-ray photoelectron spectroscopy. By controlling the energy and irradiation time of an Ar+ ion beam, Ta2O5/TaOx heterostructure can be reliably produced on ALD films, which provides a way to fabricate the critical switching layers of RRAM.

Song, W. D.; Ying, J. F.; He, W.; Zhuo, V. Y.-Q.; Ji, R.; Xie, H. Q.; Ng, S. K.; Ng, Serene L. G.; Jiang, Y.

2015-01-01

386

Ion irradiation of Allende meteorite probed by visible, IR, and Raman spectroscopies  

NASA Astrophysics Data System (ADS)

Little is known about carbonaceous asteroids weathering in space as previous studies have struggled to define a general spectral trend among dark surfaces. Here we present experiments on ion irradiation of the Allende meteorite, performed using 40 keV He+ and Ar+ ions, as a simulation of solar wind irradiation of primitive bodies surfaces. We used different fluences up to 3 × 1016 ions/cm2, corresponding to short timescales of ?103-104 yrs in the main asteroid belt. Samples were analyzed before and after irradiation using visible to far-IR (0.4-50 ?m) reflectance spectroscopy, and Raman micro-spectroscopy. Similarly to what observed in previous experiments, results show a reddening and darkening of VIS-NIR reflectance spectra. These spectral variations are however comparable to other spectral variations due to viewing geometry, grain size, and sample preparation, suggesting an explanation for the contradictory space weathering studies of dark asteroids. After irradiation, the infrared bands of the matrix olivine silicates change profile and shift to longer wavelength, possibly as a consequence of a more efficient sputtering effect on Mg than Fe (lighter and more volatile species are preferentially sputtered backwards) and/or preferential amorphization of Mg-rich olivine. Spectral variations are compatible with the Hapke weathering model. Raman spectroscopy shows that the carbonaceous component is substantially affected by irradiation: different degrees of de-ordering are produced as a function of dose, to finally end with a highly disordered carbon. All observed modifications seem to scale with the nuclear elastic dose.

Brunetto, R.; Lantz, C.; Ledu, D.; Baklouti, D.; Barucci, M. A.; Beck, P.; Delauche, L.; Dionnet, Z.; Dumas, P.; Duprat, J.; Engrand, C.; Jamme, F.; Oudayer, P.; Quirico, E.; Sandt, C.; Dartois, E.

2014-07-01

387

Irradiation effect of carbon negative-ion implantation on polytetrafluoroethylene for controlling cell-adhesion property  

NASA Astrophysics Data System (ADS)

We have investigated the irradiation effect of negative-ion implantation on the changes of physical surface property of polytetrafluoroethylene (PTFE) for controlling the adhesion property of stem cells. Carbon negative ions were implanted into PTFE sheets at fluences of 1 × 10 14-1 × 10 16 ions/cm 2 and energies of 5-20 keV. Wettability and atomic bonding state including the ion-induced functional groups on the modified surfaces were investigated by water contact angle measurement and XPS analysis, respectively. An initial value of water contact angles on PTFE decreased from 104° to 88° with an increase in ion influence to 1 × 10 16 ions/cm 2, corresponding to the peak shifting of XPS C1s spectra from 292.5 eV to 285 eV with long tail on the left peak-side. The change of peak position was due to decrease of C-F 2 bonds and increase of C-C bonds with the formation of hydrophilic oxygen functional groups of OH and C dbnd O bonds after the ion implantation. After culturing rat mesenchymal stem cells (MSC) for 4 days, the cell-adhesion properties on the C --patterned PTFE were observed by fluorescent microscopy with staining the cell nuclei and their actin filament (F-actin). The clear adhesion patterning of MSCs on the PTFE was obtained at energies of 5-10 keV and a fluence of 1 × 10 15 ions/cm 2. While the sparse patterns and the uncontrollable patterns were found at a low fluence of 3 × 10 14 ions/cm 2 and a high fluence of 3 × 10 15 ions/cm 2, respectively. As a result, we could improve the surface wettability of PTFE to control the cell-adhesion property by carbon negative-ion implantation.

Sommani, Piyanuch; Tsuji, Hiroshi; Kojima, Hiroyuki; Sato, Hiroko; Gotoh, Yasuhito; Ishikawa, Junzo; Takaoka, Gikan H.

2010-10-01

388

Encapsulation of cesium inside single-walled carbon nanotubes by plasma-ion irradiation method  

Microsoft Academic Search

Positive Cs ions are irradiated to a negatively biased substrate, which is covered with the dispersed single-walled carbon nanotubes (SWNTs) and immersed in the Cs plasma. Field emission type transmission electron microscopy (FE-TEM) and Z-contrast technique by scanning TEM (STEM) are used for the precise observation. FE-TEM gives high resolved images of structurally modified SWNTs such as irreversible bending of

Goo-Hwan Jeong; A. A. Farajian; Takamichi Hirata; Rikizo Hatakeyama; Kazuyuki Tohji; T. M. Briere; Hiroshi Mizuseki; Yoshiyuki Kawazoe

2003-01-01

389

Ion irradiation: its relevance to the evolution of complex organics in the outer solar system.  

PubMed

Ion irradiation of carbon containing ices produces several effects among which the formation of complex molecules and even refractory organic materials whose spectral color and molecular complexity both depend on the amount of deposited energy. Here results from laboratory experiments are summarized. Their relevance for the formation and evolution of simple molecules and complex organic materials on planetary bodies in the external Solar System is outlined. PMID:11541336

Strazzulla, G

1997-01-01

390

Nanoscratch testing of C60 thin films irradiated with N ions  

Microsoft Academic Search

Nanoscratch tests were performed in 170 nm thick C60 films using a depth sensing nanoindenter system with a lateral force measuring attachment. The films were irradiated with N+ ions at 170 keV and fluences ranging from 5×1011 to 5×1015N\\/cm2. The scratches were 400 \\/mum long and the used loads varied from 100 to 2500 \\/muN. The measured friction coefficient changes

J. M. J. Lopes; C. E. Foerster; F. C. Serbena; C. M. Lepienski; D. L. Baptista; F. C. Zawislak

2001-01-01

391

Nanoscratch testing of C 60 thin films irradiated with N ions  

Microsoft Academic Search

Nanoscratch tests were performed in 170 nm thick C60 films using a depth sensing nanoindenter system with a lateral force measuring attachment. The films were irradiated with N+ ions at 170 keV and fluences ranging from 5×1011 to 5×1015N\\/cm2. The scratches were 400 ?m long and the used loads varied from 100 to 2500 ?N. The measured friction coefficient changes

J. M. J. Lopes; C. E. Foerster; F. C. Serbena; C. M. Lepienski; D. L. Baptista; F. C. Zawislak

2001-01-01

392

Heavy ion irradiation of crystalline water ice. Cosmic ray amorphisation cross-section and sputtering yield  

NASA Astrophysics Data System (ADS)

Context. Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims: We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. Methods: We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results: The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions: The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice sputtering rates compete with the UV photodesorption yields reported in the literature. The prevalence of direct cosmic ray sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices. Experiments performed at the Grand Accélérateur National d'Ions Lourds (GANIL) Caen, France. Part of this work has been financed by the French INSU-CNRS programme "Physique et Chimie du Milieu Interstellaire" (PCMI) and the ANR IGLIAS.

Dartois, E.; Augé, B.; Boduch, P.; Brunetto, R.; Chabot, M.; Domaracka, A.; Ding, J. J.; Kamalou, O.; Lv, X. Y.; Rothard, H.; da Silveira, E. F.; Thomas, J. C.

2015-04-01

393

Synthesis of HCN and HNC in Ion-Irradiated N2-Rich Ices  

NASA Technical Reports Server (NTRS)

Near-IR observations reveal that N2-rich ice containing small amounts of CH4, and CO, is abundant on the surfaces of Triton, a moon of Neptune, and Pluto. N2-rich ices may also exist, in interstellar environments. To investigate the radiation chemistry of such ices we performed a systematic IR study of ion-irradiated Nz-rich mixtures containing CH4 and CO. Irradiation of N2 + CH4 mixtures at 12 K, showed that HCN, HNC, diazomethane, and NH3 were produced. We also found that UV photolysis of these ices produced detectable HCN and HNC. Intrinsic band strengths, A(HCN) and A(HNC), were measured and used to calculate yields of HCN and HNC. Similar results were obtained on irradiation of N2 + CH4 + CO ices at 12 K, with the main difference being the formation of HNCO. In all cases we observed changes on warming. For example, when the temperature of irradiated Nz + CH4 + CO was raised from 12 to 30 K, HCN, HNC, and HNCO reacted with NH3, and OCN-, CN-, N3-, and NH4+ were produced. These ions, appearing at 30 K, are expected to form and survive on the surfaces of Triton, Pluto, and interstellar grains. Our results have astrobiological implications since some of these radiation products are involved in the syntheses of biomolecules such as amino acids and peptides.

Moore, M. H.; Hudson, R. L.; Ferrante, R. F.

2002-01-01

394

Ion irradiation induced roughening and smoothing of metal films on dielectric substrates  

NASA Astrophysics Data System (ADS)

This study investigates the morphology evolution of ultrathin Pt films on dielectric substrates produced by heavy ion bombardment. The films roughen and form nanopatterns which coarsen in a certain dose range. The microstructure evolution is characterized using AFM, SEM and RBS. The results are explained using a novel irradiation induced dewetting mechanism involving local melting and viscous flow. The temperature-independent dewetting process scales with energy deposition density (J/cm2). Fissures in the initial films are identified as nuclei of dry patches for the dewetting process. Growth kinetics of the dry patches is followed using in situ TEM. Due to line tension in the curved contact lines during local melting, irradiation induced dewetting occurs much slower than dewetting under homogeneous heating. At high irradiation doses, nanopattern disappear to form nanoparticles with decreased surface roughness. The particles embed into the substrates, leading to the smoothing of the surface. The embedding kinetics is studied using cross-sectional TEM. An analytical model based on capillary driving force and viscous flow of the substrate is built to quantitatively explain the experimental results. The irradiation-induced viscosity of SiO2 is extracted to be ˜0.9 x 1023 Pa ion cm-2, consistent with previous measurements using stress relaxation.

Hu, Xiaoyuan

395

Deuterium trapping at defects created with neutron and ion irradiations in tungsten  

SciTech Connect

The effects of neutron and ion irradiations on deuterium (D) retention in tungsten (W) were investigated. Specimens of pure W were irradiated with neutrons to 0.3 dpa at around 323 K and then exposed to high-flux D plasma at 473 and 773 K. The concentration of D significantly increased by neutron irradiation and reached 0.8 at% at 473 K and 0.4 at% at 773 K. Annealing tests for the specimens irradiated with 20 MeV W ions showed that the defects which play a dominant role in the trapping at high temperature were stable at least up to 973 K, while the density decreased at temperatures equal to or above 1123 K. These observations of the thermal stability of traps and the activation energy for D detrapping examined in a previous study (˜1.8 eV) indicated that the defects which contribute predominantly to trapping at 773 K were small voids. The higher concentration of trapped D at 473 K was explained by additional contributions of weaker traps. The release of trapped D was clearly enhanced by the exposure to atomic hydrogen at 473 K, though higher temperatures are more effective for using this effect for tritium removal in fusion reactors.

Y. Hatano; M. Shimada; T. Otsuka; Y. Oya; V.Kh. Alimov; M. Hara; J. Shi; M. Kobayashi; T. Oda; G. Cao; K. Okuno; T. Tanaka; K. Sugiyama; J. Roth; B. Tyburska-Püschel; J. Dorner; N. Yoshida; N. Futagami; H. Watanabe; M. Hatakeyama; H. Kurishita; M. Sokolov; Y. Katoh

2013-07-01

396

Deuterium trapping at defects created with neutron and ion irradiations in tungsten  

NASA Astrophysics Data System (ADS)

The effects of neutron and ion irradiations on deuterium (D) retention in tungsten (W) were investigated. Specimens of pure W were irradiated with neutrons to 0.3 dpa at around 323 K and then exposed to high-flux D plasma at 473 and 773 K. The concentration of D significantly increased by neutron irradiation and reached 0.8 at% at 473 K and 0.4 at% at 773 K. Annealing tests for the specimens irradiated with 20 MeV W ions showed that the defects which play a dominant role in the trapping at high temperature were stable at least up to 973 K, while the density decreased at temperatures equal to or above 1123 K. These observations of the thermal stability of traps and the activation energy for D detrapping examined in a previous study (?1.8 eV) indicated that the defects which contribute predominantly to trapping at 773 K were small voids. The higher concentration of trapped D at 473 K was explained by additional contributions of weaker traps. The release of trapped D was clearly enhanced by the exposure to atomic hydrogen at 473 K, though higher temperatures are more effective for using this effect for tritium removal in fusion reactors.

Hatano, Y.; Shimada, M.; Otsuka, T.; Oya, Y.; Alimov, V. Kh.; Hara, M.; Shi, J.; Kobayashi, M.; Oda, T.; Cao, G.; Okuno, K.; Tanaka, T.; Sugiyama, K.; Roth, J.; Tyburska-Püschel, B.; Dorner, J.; Yoshida, N.; Futagami, N.; Watanabe, H.; Hatakeyama, M.; Kurishita, H.; Sokolov, M.; Katoh, Y.

2013-07-01

397

Modifications of yttria fully stabilized zirconia thin films by ion irradiation in the inelastic collision regime  

SciTech Connect

Yttria fully stabilized zirconia (FSZ) is a candidate material for nuclear inert matrix fuel cell and nuclear waste containment due to its isostructure with UO{sub 2} and PuO{sub 2} and its outstanding radiation resistance. Amorphous and polycrystalline cubic FSZ thin films of thickness around 400 nm were deposited on (100) Si by ultraviolet pulsed laser ablation and irradiated with 2.6 GeV uranium ions at fluences between 2x10{sup 11} and 1.2x10{sup 12} ions cm{sup -2}. The films were characterized before and after irradiation using scanning electron microscopy, atomic force microscopy, grazing incidence x-ray diffraction, and x-ray photoelectron spectroscopy (XPS). Amorphization, followed by partial recrystallization, is observed for irradiated crystalline films, whereas the amorphous films remain unaltered. A shift in the relative position of the XPS Zr 3d, Y 3d, and O 1s core lines is observed upon irradiation both in the crystalline and amorphous films, indicating differences in the local chemical environment at the surface as well as in near-surface layers. Such changes are ascribed to oxygen migration at the film surface, which may promote the recrystallization of as-deposited crystalline films but does not affect amorphous films.

Caricato, A. P. [Dipartimento di Fisica, Universita di Lecce, 73100 Lecce (Italy); Lamperti, A. [Department of Physics, Durham University, DH13LE Durham (United Kingdom); Ossi, P. M. [Dipartimento Chimica, Materiali, Ingegneria Chimica and Centre for NanoEngineered Materials and Surfaces-NEMAS, Politecnico di Milano, 20100 Milano (Italy); Trautmann, C. [Materialforschung, Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany); Vanzetti, L. [Fondazione Bruno Kessler-irst, Povo Trento 38050 (Italy)

2008-11-01

398

Influence of Ar-ions irradiation on the oxidation behavior of ferritic-martensitic steel P92 in supercritical water  

NASA Astrophysics Data System (ADS)

The corrosion behavior of ferritic-marensitic steel P92 with and without Ar-ions irradiation in supercritical water at 823 K(550 °C)/25 MPa for different exposure times was investigated by a variety of characterization techniques. A distinct difference in oxidation morphology between irradiated and unirradiated samples was observed. The oxide morphology of samples with a relatively moderate radiation intensity was similar with that of samples without irradiation. Many small oxide particles were observed in the region with a relatively high radiation intensity but their size was increased gradually with increasing exposure times. Exfoliation of oxide layer occurred for irradiated samples exposed for 100 h. Chromium-rich oxide layer with a chromium content of more than 20 wt pct along with a small-scale three-layer oxide structures were observed in Ar-ions irradiated samples, arising from the microstructural change in steel samples after the irradiation. Mechanism for the exfoliation of oxide layer is also discussed.

Huang, Xi; Shen, Yinzhong; Zhu, Jun

2015-02-01

399

Generation of silver nanoparticles with controlled size and spatial distribution by pulsed laser irradiation of silver ion-doped glass.  

PubMed

Silver ions were driven into glass by a direct current electric field-assisted ion exchange technique. The silver ion exchanged glass was then irradiated by laser pulses of 10 ns and 10 ps in length at 355 nm for comparison purposes. In both cases, laser irradiation led to the formation of a metallic-like film at the surface of the ion exchange glass. Scanning electron microscopy showed that the films consist of a very dense single layer of silver nanoparticles with similar particle sizes and separation. Irradiation with different laser parameters shows no significant difference in transmission spectra and modification width between ps- and ns-pulsed lasers. Particle sizes and separation at the surface are increasing with increasing laser power, and are larger for picosecond pulsed laser irradiation. It is also shown that the film formation is a thermal process. PMID:24663847

Wackerow, Stefan; Abdolvand, Amin

2014-03-10

400

On the maximum energy of ions in a disintegrating ultrathin foil irradiated by a high-power ultrashort laser pulse  

SciTech Connect

The theory of Coulomb explosion of a plasma is used to estimate the maximum energy of ions produced upon irradiation of an ultrathin foil by a relativistically strong ultrashort laser pulse. (interaction of laser radiation with matter. laser plasma)

Bychenkov, V Yu [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Kovalev, V F [Institute of Mathematical Modelling, Russian Academy of Sciences, Moscow (Russian Federation)

2005-12-31

401

Cellular and molecular portrait of eleven human glioblastoma cell lines under photon and carbon ion irradiation.  

PubMed

This study aimed to examine the cellular and molecular long-term responses of glioblastomas to radiotherapy and hadrontherapy in order to better understand the biological effects of carbon beams in cancer treatment. Eleven human glioblastoma cell lines, displaying gradual radiosensitivity, were irradiated with photons or carbon ions. Independently of p53 or O(6)-methylguanine-DNA methyltransferase(1) status, all cell lines responded to irradiation by a G2/M phase arrest followed by the appearance of mitotic catastrophe, which was concluded by a ceramide-dependent-apoptotic cell death. Statistical analysis demonstrated that: (i) the SF2(2) and the D10(3) values for photon are correlated with that obtained in response to carbon ions; (ii) regardless of the p53, MGMT status, and radiosensitivity, the release of ceramide is associated with the induction of late apoptosis; and (iii) the appearance of polyploid cells after photon irradiation could predict the Relative Biological Efficiency(4) to carbon ions. This large collection of data should increase our knowledge in glioblastoma radiobiology in order to better understand, and to later individualize, appropriate radiotherapy treatment for patients who are good candidates. PMID:25657111

Ferrandon, S; Magné, N; Battiston-Montagne, P; Hau-Desbat, N-H; Diaz, O; Beuve, M; Constanzo, J; Chargari, C; Poncet, D; Chautard, E; Ardail, D; Alphonse, G; Rodriguez-Lafrasse, C

2015-04-28

402

Structural behaviour of nearly stoichiometric ZrC under ion irradiation  

NASA Astrophysics Data System (ADS)

Zirconium carbide is one of the candidate materials considered as a component for the fuel elements of some nuclear reactors in the Gen-IV international project. This material has complex bonding and the actual materials have a high vacancy concentration and a non-negligible oxygen substitution on the carbon sub-network. Few data exist regarding its behaviour under irradiation. To study the structural stability of zirconium carbide in the nuclear environment, we have performed low energy ion irradiations (4 MeV Au) at room temperature of two different materials, a nearly stoichiometric ZrC 0.95 and a ternary ZrC 0.85O 0.08. Grazing Incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM) were used to monitor the microstructural changes of those materials as a function of the ion fluence. The analyses of the X-ray diffraction diagrams show a moderated swelling, lower for the ternary compound, and high internal strains, both of them saturate at a fluence around 10 14 cm -2. TEM observations show that the microscopic origin of these strains is mainly due to the formation of a high density of small faulted dislocation loops. As a result, it appears that a high substitution of carbon by oxygen in zirconium carbide does not modify the nature of the defects created under ion irradiation.

Gosset, Dominique; Dollé, Mickael; Simeone, David; Baldinozzi, Gianguido; Thomé, Lionel

2008-06-01

403

Ion beam irradiation of nanostructures: sputtering, dopant incorporation, and dynamic annealing  

NASA Astrophysics Data System (ADS)

Nanostructured materials are today subject to intense research, as their mesoscopic properties will enable a variety of new applications in the future. They can be grown with specific properties under equilibrium conditions by a variety of different top-down and bottom-up synthesis techniques. Subsequent modification, including doping or alloying using the highly non-equilibrium process of ion irradiation, significantly expands the potpourri of functionality of what is today an important material class. Important and newly discovered effects must be considered compared to ion irradiation of bulk or thin film counterparts, as the ion range becomes comparable to the size of the nanotructure. Here, we will review recent high fluence irradiation studies reporting on non-linear incorporation of implanted species, enhanced sputtering yields, morphological changes induced by the high thermal impact, as well as strongly enhanced dynamic annealing for such confined nanostructures. Our review will also include the concurrent and recent progress in developing new simulation tools in order to describe and quantify those newly observed effects.

Johannes, Andreas; Holland-Moritz, Henry; Ronning, Carsten

2015-03-01

404

In Situ TEM Concurrent and Successive Au Self-Ion Irradiation and He Implantation  

SciTech Connect

The development of advanced computational methods used for predicting performance lifetimes of materials exposed to harsh radiation environments are highly dependent on fundamental understanding of solid-radiation interactions that occur within metal components. In this work, we present successive and concurrent in situ TEM dual-beam self-ion irradiation of 2.8MeV Au4+ and implantation of 10 keV He1+, utilizing a new facility at Sandia National Laboratories. These experiments, using a model material system, provide direct real-time insight into initial interactions of displacement damage and fission products that simulate damage from neutron exposure. In successive irradiation, extensive dislocation loop and stacking fault tetrahedra damage was formed and could be associated with individual ion strikes, but no evidence of cavity formation was observed. In contrast, concurrent irradiation to the same dose resulted in the onset of cavity formation at the site of a heavy-ion stri