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1

Selected degradation reactions in polyethylene irradiated with Ar + and Xe + ions  

Microsoft Academic Search

Polyethylene (PE) was irradiated with 63 keV Ar+ and 156 keV Xe+ ions (RP=100 nm for both ions) to the fluences from 1×1013 to 3×1015 cm?2. Degradation processes in the PE surface layer, modified by the ion irradiation, were characterized by measuring depth profiles of residual hydrogen and incorporated oxygen (RBS\\/ERD techniques), free radical concentration (EPR) and conjugated double bond concentration

V Rybka; V Hnatowicz

2000-01-01

2

Selected degradation reactions in polyethylene irradiated with Ar+ and Xe+ ions  

Microsoft Academic Search

Polyethylene (PE) was irradiated with 63 keV Ar+ and 156 keV Xe+ ions (RP=100 nm for both ions) to the fluences from 1×1013 to 3×1015 cm-2. Degradation processes in the PE surface layer, modified by the ion irradiation, were characterized by measuring depth profiles of residual hydrogen and incorporated oxygen (RBS\\/ERD techniques), free radical concentration (EPR) and conjugated double bond

K. Prosková; V. Svorcík; V. Rybka; V. Hnatowicz

2000-01-01

3

Selected degradation reactions in polyethylene irradiated with Ar+ and Xe+ ions  

NASA Astrophysics Data System (ADS)

Polyethylene (PE) was irradiated with 63 keV Ar+ and 156 keV Xe+ ions (RP=100 nm for both ions) to the fluences from 1×1013 to 3×1015 cm-2. Degradation processes in the PE surface layer, modified by the ion irradiation, were characterized by measuring depth profiles of residual hydrogen and incorporated oxygen (RBS/ERD techniques), free radical concentration (EPR) and conjugated double bond concentration (UV-VIS). Dehydrogenation due to release of a part of volatile degradation products was observed. Interactions among free radicals, produced along the ion path, result in a creation of new, conjugated double bonds. Some of free radicals react with oxygen coming from ambient atmosphere in the ion implanter and in this way, oxidized structures are produced. Dehydrogenation of PE chains and degradation of oxidized structures, appear to be related to the energy locally deposited via ion electronic energy loss.

Prosková, K.; Svor?ík, V.; Rybka, V.; Hnatowicz, V.

2000-04-01

4

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

5

In situ TEM investigation of Xe ion irradiation induced defects and bubbles in pure molybdenum single crystal  

NASA Astrophysics Data System (ADS)

In order to study irradiation damage and inert gas bubble formation and growth behaviors, and to provide results and insights useful towards the validation of a multi-scale simulation approach based on a newly developed Xe-Mo inter-atomic potential, in situ Transmission Electron Microscopy (TEM) studies of Xe implantations in pure single crystal Molybdenum (Mo) have been conducted. 300 keV and 400 keV Xe+ ion beams were used to implant Xe in pre-thinned TEM Mo specimens. The irradiations were conducted at 300 °C and 600 °C to ion fluence up to 4 × 1016 ions/cm2.In situ TEM characterization allows detailed behaviors of defect clusters to be observed and is very useful in illustrating defect interaction mechanisms and processes. Dislocation loops were found to form at relatively low irradiation fluence levels. The characterization results showed that the free surfaces, formed in the process of producing pre-thinned specimens, play an important role in influencing the behaviors of dislocation loops. Similar characterizations were conducted at high fluence levels where Xe gas bubbles can be clearly observed. Xe gas bubbles were observed to form by a multi-atom nucleation process and they were immobile throughout the irradiation process at both temperatures. Measurements on both the number density and the size of dislocation loops and gas bubbles were taken. The results and implications of the measurements are discussed in this paper.

Yun, Di; Kirk, Marquis A.; Baldo, Peter M.; Rest, Jeffrey; Yacout, Abdellatif M.; Insepov, Zinetula Z.

2013-06-01

6

Color center creation in LiF crystals irradiated with Xe, Kr and N ions: Dependence on fluence and beam current density  

Microsoft Academic Search

Single LiF crystals were irradiated with Xe (195MeV), Kr (117MeV), and N (18MeV) ions. Using absorption spectroscopy, color center creation was analyzed as a function of the ion energy loss, fluence, and flux. The concentration of single F centers and F2 centers versus fluence and flux exhibits a nonlinear evolution with saturation at higher fluences. For LiF irradiated with N

A. K. Dauletbekova; A. T. Akilbekov; M. V. Zdorovets; A. F. Vassil’eva; D. A. Akilbekova

2010-01-01

7

Color center creation in LiF crystals irradiated with Xe, Kr and N ions: Dependence on fluence and beam current density  

Microsoft Academic Search

Single LiF crystals were irradiated with Xe (195 MeV), Kr (117 MeV), and N (18 MeV) ions. Using absorption spectroscopy, color center creation was analyzed as a function of the ion energy loss, fluence, and flux. The concentration of single F centers and F2 centers versus fluence and flux exhibits a nonlinear evolution with saturation at higher fluences. For LiF

A. K. Dauletbekova; A. T. Akilbekov; M. V. Zdorovets; A. F. Vassil'Eva; D. A. Akilbekova

2010-01-01

8

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

9

Effect of 690 keV Xe ion irradiation on the microstructure of amorphous MoSi{sub 2}/SiC nanolayer composites  

SciTech Connect

The effect of 690 keV Xe ion irradiation at three different dosage levels, 1, 5 and 10{times}10{sup 15}/cm{sup 2}, on the microstructure of amorphous-MoSi{sub 2}/amorphous-SiC nanolayer composites has been studied using transmission electron microscopy. Results show that the depth of radiation damage in this multilayer material is {approximately}80 nm, which agrees qualitatively well with the calculated damage depth calculated by TRIM. A diffraction ring corresponding to the (10{bar 1}1) plane of C40 MoSi{sub 2} was found in the electron diffraction pattern taken from the irradiated regions; the C40 phase is also found after thermal annealing of amorphous MoSi{sub 2} at 500{degrees}C or above. In the damaged regions SiC layers were found to spherodize while the nanocrystalline grains in the MoSi{sub 2} layers appeared to coarsen with increasing dose.

Lu, Y.C.; Kung, H.; Jervis, T.R.; Mitchell, T.E.; Nastasi, M. [and others

1996-10-01

10

High-resolution photoionization of Xe+ ions: Experiment and theory  

NASA Astrophysics Data System (ADS)

High-resolution photoionization measurements of Xe+ ions have been performed at the Advanced Light Source in Berkeley, California, USA. The experimental cross sections are compared with results from Dirac-Coulomb R-matrix calculations.

Aguilar, A.; Alna'washi, G.; Bilodeau, R. C.; Carr, A.; Esteves, D. A.; Kilcoyne, A. L. D.; Mülled, A.; Phaneuf, R. A.; Red, E.; Schippers, S.; Sterling, N. C.; Ballance, C. P.; McLaughlin, B. M.

2012-11-01

11

Xe precipitates at grain boundaries in Al under 1 MeV electron irradiation.  

SciTech Connect

Crystalline nanoprecipitates of Xe have been produced by ion implantation into mazed bicrystalline Al at 300 K, in which the matrix grain boundaries are mainly 90 deg tilt boundaries. Within Al grains, Xe nanocrystals are fee, isotactic with the Al and cuboctohedral in shape with {l_brace}111{r_brace} and {l_brace}100{r_brace} facets. With an off-axial imaging technique, the nanocrystals were structure imaged against a relatively featureless matrix background. In contrast to metal precipitates in Al, such as Pb, Xe precipitates straddling a matrix grain boundary are bicrystals as small as approximately 2 nm in diameter. Larger Xe precipitates tend to avoid boundaries which are inclined away from asymmetrical orientation and which thus have a significant twist component. Under the 1 MeV electron irradiation employed for HREM observation, small Xe nanocrystals near a grain boundary may migrate to the boundary and coalesce with other Xe precipitates. The structural observations are rationalized on a simple geometrical interpretation.

Allen, C. W.

1998-10-23

12

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

13

Molecular dynamic studies on anisotropic explosion of laser irradiated Xe cluster  

NASA Astrophysics Data System (ADS)

A three dimensional molecular dynamic model is used to investigate the dynamics of Xe clusters of various radii irradiated by laser of moderate intensities (~1014-1016W/cm2). The FWHM pulse duration of the laser is varied from few laser cycles to hundreds of femtosecond. For cluster of radius 50 A? irradiated by a laser of 170 fs pulse duration, it is observed that ion yield is more along the direction of laser polarization than perpendicular to it. This trend reverses (more ions are emitted along the direction perpendicular to laser polarization than parallel to it) when laser pulses of few cycles are used. This reversal of anisotropy is explained on the basis of spatial shielding of ions due to the oscillating inner electron cloud along direction of laser electric field. The nature of anisotropy remains same with variations in laser intensity and cluster size.

Mishra, Gaurav; Gupta, N. K.

2012-09-01

14

Color center formation in silica glass induced by high energy Fe and Xe ions  

Microsoft Academic Search

Silica glass samples were implanted with 1.157GeV 56Fe and 1.755GeV 136Xe ions to fluences range from 1×1011 to 3.8×1012 ions\\/cm2. Virgin and irradiated samples were investigated by ultraviolet (UV) absorption from 3 to 6.4eV and photoluminescence (PL) spectroscopy. The UV absorption investigation reveals the presence of various color centers (E? center, non-bridging oxygen hole center (NBOHC) and ODC(II)) appearing in

Mingwang Ma; Xiliang Chen; Kang Yang; Xiaomin Yang; Youmei Sun; Yunfan Jin; Zhiyong Zhu

2010-01-01

15

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

16

Ion irradiation induced grain growth in Pd polycrystalline thin films  

Microsoft Academic Search

Ion irradiation induced grain growth in Pd polycrystalline thin films was studied by transmission electron microscopy for 100-keV Ne+, 185-keV Ar+, and 560-keV Xe++ irradiations over a wide range of doses. Grain growth from 9 to 60 nm was observed after ion irradiations. Initially, the amount of growth is approximately linear with the irradiation dose; the growth saturates in the

Joyce C. Liu; M. Nastasi; J. W. Mayer

1987-01-01

17

Ion mobilities in Xe\\/Ne and other rare-gas mixtures  

Microsoft Academic Search

The ion mobility or drift velocity data important for modeling glow discharges in rare gas mixtures are not generally available, nor are the ion-neutral scattering cross sections needed to calculate these data. In this paper we propose a set of cross sections for Xe+ and Ne+ collisions with Xe and Ne atoms. Ion mobilities at 300 K calculated using this

D. Piscitelli; A. V. Phelps; J. de Urquijo; E. Basurto; L. C. Pitchford

2003-01-01

18

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

NASA Astrophysics Data System (ADS)

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-, L1-, L2,3-, M1-, M2,3- and M4,5 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 Xe7+, Xe8+, Xe9+ and Xe10+ ions, and the charged X8+ ions are the highest. The main product from the L1- shell ionization is found to be Xe8+, Xe9+ ions, while the charged Xe8+ ions predominate at L2,3 hole states. The charged Xe6+, Xe7+ and Xe8+ ions mainly yield from 3s1/2 and 3p1/2,3/2 ionization, while Xe in 3d3/2,5/2 hole states mainly turns into Xe4+ and Xe5+ 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.

2010-01-01

19

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

20

Ion acceleration in Ar-Xe and Ar-He plasmas. II. Ion velocity distribution functions  

SciTech Connect

Ion velocity distribution functions (ivdfs) are investigated by laser induced fluorescence in Ar-Xe and Ar-He expanding helicon plasmas as a function of gas composition. In the case of Ar-Xe plasma, it was found that in the helicon source, both the Ar{sup +} and Xe{sup +} vdfs are unimodal. Their parallel speeds are subsonic and unaffected by changes in gas composition. At the end of the source, the argon ivdf shows a bimodal structure indicative of an electric double layer upstream of the measurement location. The fast argon ion component parallel velocity increases with Xe fraction from 6.7 to 8 km/s as the Xe fraction increases from 0% to 4%. In the expansion region, the bimodal character of Ar ivdf is maintained with a supersonic fast component reaching parallel speeds of 10.5 km/s. For all the studied plasma conditions and different spatial locations, the Xe{sup +} vdf exhibits a unimodal structure with a maximum parallel flow velocity of 2.2 km/s at the end of the source. For Ar-He plasma, the Ar ivdf is bimodal with the fast ion component parallel velocity increasing from 5.2 to 7.8 km/s as the He fraction increases from 0% to 30%. For the same He fraction range, the slow argon ion population distribution changes from a single Gaussian to a wide distribution extending all the way from the speed of the fast population to 0 m/s.

Biloiu, Ioana A.; Scime, Earl E. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)

2010-11-15

21

MOMS and PAC studies of ion-irradiated ferromagnetic films  

Microsoft Academic Search

Thin polycrystalline films of Ni, Fe and Co, tens of nanometers thick, have been irradiated with Ar, Kr, Xe and\\/or Au ions\\u000a to fluences of 1013 to 1016 ions\\/cm2. The magnetic texture induced or modified by the implanted ions has been measured by hyperfine methods, such as Magnetic\\u000a Orientation Mössbauer (Fe) or Perturbed Angular Correlation Spectroscopy (Ni), and by Magneto-Optical

G. A. Müller; A. Kulinska; Kun Zhang; R. Gupta; P. Schaaf; M. Uhrmacher; K. P. Lieb

2003-01-01

22

Large-angle xenon ion scattering in Xe-propelled electrostatic thrusters: differential cross sections  

NASA Astrophysics Data System (ADS)

Elastic scattering between xenon ions and xenon atoms can produce ion currents at large angles with respect to the axis of electrostatic thrusters. Differential scattering cross sections are needed to properly predict off-axis currents that can cause significant material erosion due to sputtering. Guided-ion beam differential cross section measurements are presented for Xe+ + Xe and Xe2+ + Xe elastic scattering at laboratory ion energies between 5 and 40 eV per ion charge. For the singly charged system, the experimental absolute differential cross sections are in excellent agreement with classical elastic scattering calculations based on the most recent ab initio ion-atom interaction potentials. The measurements for the doubly charged system are used to derive an approximate effective Xe2+-Xe interaction potential. The potentials are used to calculate absolute differential cross sections for both ion charge states at a typical Hall thruster ion energy of 270 eV per unit charge. The differential cross sections for the doubly charged ions are approximately a factor of 3 smaller than those of the singly charged system at large scattering angles. The importance of doubly charged ions with respect to material erosion is discussed on the basis of known sputtering yields as a function of ion energy for molybdenum and boron nitride. It is concluded that at typical charge-state ratios, doubly charged ions only have an impact at elastic scattering angles where the scattered ion energy in the laboratory (thruster) frame of reference is low and the sputtering yields depend very strongly on ion kinetic energy.

Chiu, Y.-H.; Dressler, R. A.; Levandier, D. J.; Houchins, C.; Ng, C. Y.

2008-08-01

23

Grain Growth and Phase Formation in Ion-Irradiated Metal Alloy Thin Films  

Microsoft Academic Search

Phase formation was studied in Ni^ {+} and Xe^{+} ion irradiated multilayer and coevaporated Ni-20 at.% Al films. Irradiation resulted in the formation of metastable supersaturated gamma and HCP phases in both film types. Strong irradiation-induced textures were observed in the multilayers that were less pronounced in the coevaporated films. The texture in the multilayers was attributed to the presence

Dale Edward Alexander

1990-01-01

24

Nanoparticle ejection from gold during ion irradiation.  

SciTech Connect

We have used in situ transmission electron microscopy to study the sputtering of gold by inert-gas ions and, in particular, nanoparticles ejected by individual ion impacts. Irradiations were performed at room temperature in transmission geometry with Ne, Ar, Kr and Xe ions at energies between 100 and 600 keV. Nanoparticles result from situations in which ion impacts also give rise to nanometer size craters on the surface. The number of nanoparticles increased linearly with increasing ion dose. The rate of nanoparticle ejection scales with the probability, calculated with standard Monte Carlo techniques, for high-energy deposition events by individual ions in the near-surface region regardless of the irradiation. The percentage of near-surface, high-energy recoils that eject a nanoparticle is high. The rate of nanoparticle ejection depends on energy transfer to the Au lattice and not on the ion that makes the impact or its energy. Ejected nanoparticles account for the nonlinear component of sputtering. Monte Carlo calculations offer a general technique for predicting situations in which nanoparticles can be ejected and thus when the nonlinear contribution to the sputtering yield is likely to be significant.

Birtcher, R. C.; Donnelly, S. E.; Schlutig, S.; Materials Science Division; Univ. of Salford; Univ. of Caen

2004-01-01

25

Track lengths of energetic 132Xe ions in CR-39 detectors  

NASA Astrophysics Data System (ADS)

Studies of particle tracks in solids have wide ranging applications in many diverse fields of science and technology. Most of these studies require a precise knowledge of heavy ion track lengths or ranges in various knowledge of heavy ion track lengths or ranges in various commonly used solid dielectrics. We have measured the maximum etchable track lengths of 132Xe at 12 different energies ranging from 5.8 MeV/u to 17.0 MeV/u in CR-39 (Homalite). The ion beam with an initial energy of 17.0 MeV/u was degraded by aluminium foils of different thickness. The detectors were irradiated at an angle of 45° to the beam direction and were etched for a period of 2?6 hrs in 6N NaOH at 55°C to reveal the tracks. The track lengths were measured using an optical microscope and the maximum etchable track lengths were determined. The standard deviations have been evaluated and the experimental results are compared with theoretical values obtained from computer codes ?RANGE? and ?TRIM? and the program of Henke and Benton.

Ghosh, S.; Raju, J.; Dwivedi, K. K.

1994-06-01

26

Optima XE Single Wafer High Energy Ion Implanter  

SciTech Connect

The Optima XE is the first production worthy single wafer high energy implanter. The new system combines a state-of-art single wafer endstation capable of throughputs in excess of 400 wafers/hour with a production-proven RF linear accelerator technology. Axcelis has been evolving and refining RF Linac technology since the introduction of the NV1000 in 1986. The Optima XE provides production worthy beam currents up to energies of 1.2 MeV for P{sup +}, 2.9 MeV for P{sup ++}, and 1.5 MeV for B{sup +}. Energies as low as 10 keV and tilt angles as high as 45 degrees are also available., allowing the implanter to be used for a wide variety of traditional medium current implants to ensure high equipment utilization. The single wafer endstation provides precise implant angle control across wafer and wafer to wafer. In addition, Optima XE's unique dose control system allows compensation of photoresist outgassing effects without relying on traditional pressure-based methods. We describe the specific features, angle control and dosimetry of the Optima XE and their applications in addressing the ever-tightening demands for more precise process controls and higher productivity.

Satoh, Shu; Ferrara, Joseph; Bell, Edward; Patel, Shital; Sieradzki, Manny [Axcelis Technologies, Inc. 108 Cherry Hill Drive, Beverly, MA 01915 (United States)

2008-11-03

27

Ion acceleration in Ar-Xe and Ar-He plasmas. I. Electron energy distribution functions and ion composition  

SciTech Connect

Electron energy distribution functions (eedf), ion production, and ion composition are studied in Ar-Xe and Ar-He expanding helicon plasmas. It was found that under the conditions of constant total flow rate, Xe, in addition to Ar, changes the eedf from Maxwellian-like to Druyvesteyn-like with a shortening of the high energy tail at {approx}15 eV. The electron temperature exponentially decreases from {approx}7 eV in pure Ar plasma to {approx}4 eV in pure Xe plasma. Xenon ions dominate the ion population for Xe filling fractions greater than 10%. The plasma density increases by {approx}15% with increasing Xe fraction. For an Ar-He plasma, increasing the helium fraction increases the electron temperature from {approx}7 eV in pure Ar plasma to {approx}14 eV for a He filling fraction of 80%. The plasma density drops by more than three orders of magnitude from 1.14x10{sup 11} cm{sup -3} to 6.5x10{sup 7} cm{sup -3}. However, the inferred ion densities indicate that even at a helium fraction of 80%, argon ions significantly outnumber helium ions.

Biloiu, Ioana A.; Scime, Earl E. [Department of Physics, West Virginia University, Morganton, West Virginia 26506 (United States)

2010-11-15

28

Radiation damage factor for ion-implanted silicon detectors irradiated with heavy ions  

Microsoft Academic Search

Ion-implanted silicon detectors were irradiated with 18-150 MeV 16O, 20 MeV 40Ar, and 53 MeV 110Xe. A linear increase of the leakage current was observed as a function of the particle fluence up to 2.2×108 cm-2. Extracted damage factors are proportional to the averaged nuclear stopping power over five orders of magnitude covering heavy ions studied in the present work

M. Kurokawa; T. Motobayashi; K. Ieki; S. Shimoura; H. Murakami; Y. Ikeda; S. Moriya; Y. Yanagisawa; T. Nomura

1995-01-01

29

The effect of ion irradiation on inert gas bubble mobility  

SciTech Connect

The effect of Al ion irradiation on the mobility of Xe gas bubbles in Al thin films was investigated. Transmission electron microscopy was used to determine bubble diffusivities in films irradiated and/or annealed at 673K, 723K and 773K. Irradiation increased bubble diffusivity by a factor of 2--9 over that due to thermal annealing alone. The Arrhenius behavior and dose rate dependence of bubble diffusivity are consistent with a radiation enhanced diffusion phenomenon affecting a volume diffusion mechanism of bubble transport. 9 refs., 3 figs., 2 tabs.

Alexander, D.E.; Birtcher, R.C.

1991-09-01

30

Ion irradiation effects on bcc Fe\\/Tb multilayers  

Microsoft Academic Search

Fe\\/Tb multilayers with crystallized Fe layers were irradiated with Kr, Xe, Pb, and U ions at various fluences. Damaging processes, investigated by 57Fe Möautssbauer spectrometry at room temperature, give evidence for two thresholds, one for Fe-Tb mixing (T1~25 keV\\/nm) and one relative to the creation of defects in the bcc Fe layers (T2~45 keV\\/nm). If the electronic stopping power (dE\\/dx)e

J. Teillet; F. Richomme; A. Fnidiki; M. Toulemonde

1997-01-01

31

Simultaneous imaging electron- and ion-feature Thomson scattering measurements of radiatively heated Xe  

NASA Astrophysics Data System (ADS)

Uniform density and temperature Xe plasmas have been produced over >4 mm scale-lengths using x-rays generated in a cylindrical Pb cavity. The cavity is 750 ?m in depth and diameter, and is heated by a 300 J, 2 ns square, 1054 nm laser pulse focused to a spot size of 200 ?m at the cavity entrance. The plasma is characterized by simultaneous imaging Thomson scattering measurements from both the electron and ion scattering features. The electron feature measurement determines the spatial electron density and temperature profile, and using these parameters as constraints in the ion feature analysis allows an accurate determination of the charge state of the Xe ions. The Thomson scattering probe beam is 40 J, 200 ps, and 527 nm, and is focused to a 100 ?m spot size at the entrance of the Pb cavity. Each system has a spatial resolution of 25 ?m, a temporal resolution of 200 ps (as determined by the probe duration), and a spectral resolution of 2 nm for the electron feature system and 0.025 nm for the ion feature system. The experiment is performed in a Xe filled target chamber at a neutral pressure of 3-10 Torr, and the x-rays produced in the Pb ionize and heat the Xe to a charge state of 20+/-4 at up to 200 eV electron temperatures.

Pollock, B. B.; Meinecke, J.; Kuschel, S.; Ross, J. S.; Shaw, J. L.; Stoafer, C.; Divol, L.; Tynan, G. R.; Glenzer, S. H.

2012-10-01

32

Simultaneous imaging electron- and ion-feature Thomson scattering measurements of radiatively heated Xe.  

PubMed

Uniform density and temperature Xe plasmas have been produced over >4 mm scale-lengths using x-rays generated in a cylindrical Pb cavity. The cavity is 750 ?m in depth and diameter, and is heated by a 300 J, 2 ns square, 1054 nm laser pulse focused to a spot size of 200 ?m at the cavity entrance. The plasma is characterized by simultaneous imaging Thomson scattering measurements from both the electron and ion scattering features. The electron feature measurement determines the spatial electron density and temperature profile, and using these parameters as constraints in the ion feature analysis allows an accurate determination of the charge state of the Xe ions. The Thomson scattering probe beam is 40 J, 200 ps, and 527 nm, and is focused to a 100 ?m spot size at the entrance of the Pb cavity. Each system has a spatial resolution of 25 ?m, a temporal resolution of 200 ps (as determined by the probe duration), and a spectral resolution of 2 nm for the electron feature system and 0.025 nm for the ion feature system. The experiment is performed in a Xe filled target chamber at a neutral pressure of 3-10 Torr, and the x-rays produced in the Pb ionize and heat the Xe to a charge state of 20±4 at up to 200 eV electron temperatures. PMID:23127005

Pollock, B B; Meinecke, J; Kuschel, S; Ross, J S; Shaw, J L; Stoafer, C; Divol, L; Tynan, G R; Glenzer, S H

2012-10-01

33

Simultaneous imaging electron- and ion-feature Thomson scattering measurements of radiatively heated Xe  

SciTech Connect

Uniform density and temperature Xe plasmas have been produced over >4 mm scale-lengths using x-rays generated in a cylindrical Pb cavity. The cavity is 750 {mu}m in depth and diameter, and is heated by a 300 J, 2 ns square, 1054 nm laser pulse focused to a spot size of 200 {mu}m at the cavity entrance. The plasma is characterized by simultaneous imaging Thomson scattering measurements from both the electron and ion scattering features. The electron feature measurement determines the spatial electron density and temperature profile, and using these parameters as constraints in the ion feature analysis allows an accurate determination of the charge state of the Xe ions. The Thomson scattering probe beam is 40 J, 200 ps, and 527 nm, and is focused to a 100 {mu}m spot size at the entrance of the Pb cavity. Each system has a spatial resolution of 25 {mu}m, a temporal resolution of 200 ps (as determined by the probe duration), and a spectral resolution of 2 nm for the electron feature system and 0.025 nm for the ion feature system. The experiment is performed in a Xe filled target chamber at a neutral pressure of 3-10 Torr, and the x-rays produced in the Pb ionize and heat the Xe to a charge state of 20{+-}4 at up to 200 eV electron temperatures.

Pollock, B. B. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093 (United States); Meinecke, J. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); University of Oxford, Wellington Square, Oxford, OX1 2JD (United Kingdom); Kuschel, S.; Ross, J. S.; Divol, L.; Glenzer, S. H. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Shaw, J. L. [University of California, Los Angeles, 405 Hilgard Ave., Los Angeles, California 90095 (United States); Stoafer, C. [Columbia University, 116th Street and Broadway, New York, New York 10027 (United States); Tynan, G. R. [University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093 (United States)

2012-10-15

34

Effects of high-energy heavy ion irradiation on the crystal structure in CeO2 thin films  

NASA Astrophysics Data System (ADS)

We studied the change in crystal structure of 200 MeV Xe and 10 MeV I ion irradiated CeO2 thin films by means of X-ray diffraction (XRD). The experimental result showed that the average lattice parameter of CeO2 decreased and the full width at half maximum increased by the ion irradiation. Their changes are well correlated with the electronic stopping powers for I and Xe ions. The dependence of lattice parameter on the electronic energy loss was analyzed by using the Poisson's law, and the radii of the regions affected by the irradiation were determined.

Kishino, T.; Shimizu, K.; Saitoh, Y.; Ishikawa, N.; Hori, F.; Iwase, A.

2013-11-01

35

Double-electron removal from H2 by slow, highly charged Xe23+ ions  

Microsoft Academic Search

A five-body classical trajectory Monte Carlo model has been used to study double-electron removal from H2 by collisions with highly charged ions. The final-state correlations between ionized protons and projectile are calculated for Xe23+ impact on H2 at collision energies ranging from 2.6 eV u-1 to 2.6 keV u-1. In the centre-of-mass frame of the recoiling protons, as the projectile

R. E. Olson; C. R. Feeler

2001-01-01

36

Kr and Xe ions implanted on the surfaces of Mo, Hf, Ta, W, Re, Au and platinum group elements  

NASA Astrophysics Data System (ADS)

Kr and Xe ion bombardment experiments were conducted on Mo, Hf, Ta, W, Re, Au, and five platinum group elements. The implanted Kr and Xe ions were detected, and their concentrations were determined by X-ray photoelectron spectroscopy (XPS) using synchrotron radiation. In the case of 5d transition metals, the binding energies of Kr2p3/2, Xe3d3/2, and Xe3d5/2 in the target metals correlate with the number of d electrons of metals. Furthermore, the Xe concentration in the 5d transition metals correlates with atomic number, but there is no such correlation for Kr. The observed trend for the Xe concentration can approximately be reproduced by a theoretical calculation that takes sputtering yield into consideration. The retentivities of Kr and Xe are defined as the ratio of the experimental and theoretical surface concentrations. Although there is no correlation between retentivity and the atomic number of the target metal, the elastic energies in the cases of Kr and Xe atoms implanted in metals positively correlate with the corresponding retentivities. If the activation energy of noble-gas diffusion in the target metals can be represented in terms of the elastic energy, the noble-gas retentivity can be qualitatively explained.

Osawa, Takahito

2012-03-01

37

Ion energy distributions, electron temperatures, and electron densities in Ar, Kr, and Xe pulsed discharges  

SciTech Connect

Ion energy distributions (IEDs) were measured near the edge of Faraday-shielded, inductively coupled pulsed plasmas in Ar, Kr, or Xe gas, while applying a synchronous dc bias on a boundary electrode, late in the afterglow. The magnitudes of the full width at half maximum of the IEDs were Xe > Kr > Ar, following the order of the corresponding electron temperatures in the afterglow, T{sub e}(Xe) > T{sub e}(Kr) > T{sub e}(Ar). The measured decays of T{sub e} with time in the afterglow were in excellent agreement with predictions from a global model. Measured time-resolved electron and positive ion densities near the plasma edge did not decay appreciably, even in the 80 {mu}s long afterglow. This was attributed to transport of ions and electrons from the higher density central region of the plasma to the edge region, balancing the loss of plasma due to diffusion. This provides a convenient means of maintaining a relatively constant plasma density in the afterglow during processing using pulsed plasmas.

Shin, Hyungjoo; Zhu Weiye; Economou, Demetre J.; Donnelly, Vincent M. [Plasma Processing Laboratory, Department of Chemical and Biomolecular Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204-4004 (United States)

2012-05-15

38

In situ HVEM study of ion irradiation-induced grain growth in Au thin films  

SciTech Connect

In situ observations of 1.5 MeV Xe/sup +/ ion irradiated Au films at room temperature and at 150/degree/C reveal the evolution of grain growth: the average grain size increases by the mechanisms of grain boundary migration and grain coalescence. 10 refs., 4 figs.

Liu, J.C.; Li, Jian; Mayer, J.W.; Allen, C.W.; Rehn, L.E.

1989-01-01

39

In situ HVEM study of ion irradiation-induced grain growth in Au thin films  

Microsoft Academic Search

In situ observations of 1.5 MeV Xe\\/sup +\\/ ion irradiated Au films at room temperature and at 150\\/degree\\/C reveal the evolution of grain growth: the average grain size increases by the mechanisms of grain boundary migration and grain coalescence. 10 refs., 4 figs.

J. C. Liu; Jian Li; J. W. Mayer; C. W. Allen; L. E. Rehn

1989-01-01

40

Effect of ion irradiation on a Co-based amorphous ribbon  

SciTech Connect

The effects of ion irradiation on a giant magnetoimpedance (GMI) have been investigated for a Co-based amorphous ribbon with various kinds of ions such as Xe, Ar, and N. The GMI ratio and M-H loop parameters were used to characterize the samples before and after the ion irradiation. The GMI ratio increased considerably in the ion irradiated samples and the GMI response showed a strong dependence on the irradiated ion species and driving frequencies. It was shown that the ion irradiations lead to a substantial modification of the magnetic properties including a large coercivity and shearing of the in-plane magnetization loops, thus suggesting the reduction of an exchange coupling.

Park, D. G.; Kim, C. G.; Lee, J. H.; Kim, W. W.; Hong, J. H. [Korea Atomic Energy Research Institute, P.O. Box 105, Yuseong, Daejeon 305-600 (Korea, Republic of); Department of Materials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Korea Atomic Energy Research Institute, P.O. Box 105, Yuseong, Daejeon 305-600 (Korea, Republic of)

2007-05-01

41

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

42

Change in magnetic properties induced by swift heavy ion irradiation in CeO2  

NASA Astrophysics Data System (ADS)

We have studied the magnetic properties of pure CeO2 irradiated with swift heavy ions. Experimental results showed that the ferromagnetism was induced even at room temperature by 200 MeV Xe ion irradiation. The value of saturation magnetization, Ms, systematically changes as a function of ion-fluence. The value of Ms increases with increasing the ion-fluence and reaches a maximum value at about the fluence of 2.0 × 1013/cm2, and then decreases. The X-ray diffraction (XRD) spectra show that the lattice constant of CeO2 increases with increasing ion-fluence. This result and our previous XPS result show that the ion-irradiation produced oxygen vacancies. The present study implies that the ferromagnetic behavior of the ion-irradiated CeO2 is attributed to the magnetic moments of localized 4f electrons on Ce3+ atoms, which are related to oxygen vacancies.

Shimizu, K.; Kosugi, S.; Tahara, Y.; Yasunaga, K.; Kaneta, Y.; Ishikawa, N.; Hori, F.; Matsui, T.; Iwase, A.

2012-09-01

43

The effect of defects caused by Xe ion bombardment on the structure of Au\\/GaAs contacts  

Microsoft Academic Search

The effect of Xe ion treatment (700 keV, 1014Xe2+\\/cm2) on the interaction between Au(55 nm)\\/GaAs(100) was studied using RBS (Rutherford backscattering spectrometry) and TEM (transmission electron microscopy). Samples were annealed rapidly in UHV with a heating rate of 150°C\\/min while the evaporation of the volatile component (As) was monitored with a mass spectrometer. Taking the evaporation vs temperature curves into

Erika Jároli; J. Gyulai; B. Pécz; R. Veresegyházy; G. Radnóczi; P. B. Barna

1993-01-01

44

Effect of swift heavy ion irradiation on the short range order in novel electrodeposited ternary amorphous alloys  

NASA Astrophysics Data System (ADS)

The effect of swift heavy ion irradiation in novel electrodeposited ternary amorphous alloys was studied by 57Fe and 119Sn conversion electron Mössbauer spectroscopy. Irradiation of Sn3Co3Fe with 246 MeV Kr ions induces partial segregation and rearrangement of the constituent elements from the amorphous state toward an ordered state. The Sn3Ni3Fe irradiated with 600 MeV Xe ions exhibits transformation from the as-deposited amorphous toward a slightly more disordered state due to the swift heavy ion irradiation.

Stichleutner, S.; Kuzmann, E.; Lak, G. B.; El-Sharif, M.; Chisholm, C. U.; Havancsák, K.; Skuratov, V. A.; Sziráki, L.; Homonnay, Z.; Vértes, A.

2013-10-01

45

Temperature effect on ion-irradiation-induced grain growth in Cu thin films  

Microsoft Academic Search

The average grain size in Ar{sup +}-irradiated Cu films at room temperature increases with ion dose, following a relationship of {bar {ital d}}{sup 3.3}-{bar {ital d}}{sup 3.3}â ={ital K}Ï. For Ar{sup +} and Xe{sup ++} irradiations, the grain growth kinetics are independent of temperature at {ital T}â¤-60 °C and increase with temperature in the range from -60 to 102 °C.

Joyce C. Liu; Jian Li; J. W. Mayer

1990-01-01

46

Temperature effect on ion-irradiation-induced grain growth in Cu thin films  

Microsoft Academic Search

The average grain size in Ar+-irradiated Cu films at room temperature increases with ion dose, following a relationship of d¯3.3?d¯3.30 =K?. For Ar+ and Xe++ irradiations, the grain growth kinetics are independent of temperature at T??60 °C and increase with temperature in the range from ?60 to 102 °C. The activation energy of the temperature-dependent contribution to grain boundary migration

Joyce C. Liu; Jian Li; J. W. Mayer

1990-01-01

47

Modification of structure and optical band-gap of nc-Si:H films with ion irradiation  

NASA Astrophysics Data System (ADS)

Hydrogenated nano-crystalline silicon (nc-Si:H) films fabricated by using hot-wire chemical vapor deposition are irradiated at room temperature with 6.0 MeV Xe-ions. The irradiation fluences are 1.0 × 1013, 5.0 × 1013 and 1.0 × 1014 Xe-ions/cm2. The structure and optical band-gap of the irradiated films varying with ion fluence are investigated by means of X-ray diffraction, Raman and UV-Vis-NIR spectroscopes, as well as transmission electron microscopy. It is found that the crystallite size, the crystalline fraction and the optical band-gap decrease continuously with increasing the ion fluence. The crystalline fraction of the films irradiated to the fluences from 0 to 1.0 × 1014 Xe-ions/cm2 decreases from about 65.7% to 2.9% and the optical band-gap decreases from about 2.1 to 1.6 eV. Possible origins of the modification of the nc-Si:H films under 6.0 MeV Xe-ions irradiation are briefly discussed.

Zhu, Yabin; Wang, Zhiguang; Sun, Jianrong; Yao, Cunfeng; Shen, Tielong; Li, Bingsheng; Wei, Kongfang; Pang, Lilong; Sheng, Yanbin; Cui, Minghuan; Li, Yuanfei; Wang, Ji; Zhu, Huiping

2012-09-01

48

Electron stripping at MeV/u energies for U ^28+ and Xe^18+ ions .  

NASA Astrophysics Data System (ADS)

Beam lifetimes were measured for 10 MeV/u to75 MeV/u Xe^18+ and 10 MeV/u to 50 MeV/u U ^28+. Lifetimes resulting from interactions with background gases at base pressures in the GSI ESR storage ring and for molecular hydrogen and molecular nitrogen were measured. For H2 and N2 , ion beams where injected in the ESR and a fast valve was opened to admit the supersonic jet from the ESR gas target. The N2 results imply that the stripping cross section has approximately a v-1 dependence, whereas the H2 results imply nearly a v-2 dependence.

Dubois, Robert; de Lucio, Oscar; Thomason, Mark

2006-05-01

49

Structural modification of C-doped SiO2 induced by swift heavy ion irradiations  

NASA Astrophysics Data System (ADS)

Thermally grown amorphous SiO2 samples were implanted at room temperature (RT) with 120 keV C-ions to a dose ranging from 1.0 × 1016 to 8.6 × 1017C ions/cm2, then irradiated at RT with 950 MeV Pb, 345 or 1754 MeV Xe ions to a fluence in the region from 1.0 × 1011 to 3.8 × 1012 ions/cm2, respectively. The irradiated samples were investigated using micro-FTIR and micro-Raman spectroscopes. It was found that new chemical bonds such as Si C, CC(O), CC and Si(C) O C bonds formed significantly in the C-doped SiO2 films after heavy ion irradiations. The evolution of Si O C bonds and possible mechanism of structural modification in C-doped SiO2 induced by swift heavy ion irradiations were discussed.

Wang, Z. G.; Zhao, Z. M.; Benyagoub, A.; Toulemonde, M.; Levesque, F.; Song, Y.; Jin, Y. F.; Sun, Y. M.; Liu, C. B.; Zang, H.; Wei, K. F.

2007-03-01

50

Accumulation of mechanical stress in Al2O3:Cr under swift heavy ion irradiation  

Microsoft Academic Search

The build-up and accumulation of stresses in Al2O3:Cr single crystalline samples under 670 MeV Bi, 167 MeV Xe and 107 MeV Kr ion irradiation have been studied using ion-beam-induced luminescence measurements. The stress level has been deduced from R-line luminescence spectra measured in situ on the basis of the piezospectroscopic effect. The experimental data have revealed different stages in the

G. Bujnarowski; V. A. Skuratov; K. Havancsak; Yu S. Kovalev

2009-01-01

51

Accumulation of mechanical stress in Al2O3:Cr under swift heavy ion irradiation  

Microsoft Academic Search

The build-up and accumulation of stresses in Al2O3:Cr single crystalline samples under 670 MeV Bi, 167 MeV Xe and 107 MeV Kr ion irradiation have been studied using ion-beam-induced luminescence measurements. The stress level has been deduced from R-line luminescence spectra measured in situ on the basis of the piezospectroscopic effect. The experimental data have revealed different stages in the stress accumulation processes

G. Bujnarowski; V. A. Skuratov; K. Havancsak; Yu. S. Kovalev

2009-01-01

52

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; Tr?bert, E

2007-03-27

53

Study on the behavior of oxygen atoms in swift heavy ion irradiated CeO 2 by means of synchrotron radiation X-ray photoelectron spectroscopy  

Microsoft Academic Search

To study the effects of swift heavy ion irradiation on cerium dioxide (CeO2), CeO2 sintered pellets were irradiated with 200MeV Xe ions at room temperature. For irradiated and unirradiated samples, the spectra of X-ray photoelectron spectroscopy (XPS) were measured. XPS spectra for the irradiated samples show that the valence state of Ce atoms partly changes from +4 to +3. The

A. Iwase; H. Ohno; N. Ishikawa; Y. Baba; N. Hirao; T. Sonoda; M. Kinoshita

2009-01-01

54

Surface amorphization in Al2O3 induced by swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

Microstructure in single crystalline Al2O3 developed during irradiation by swift heavy ions has been investigated. The specimens were irradiated by Xe ions with energies from 70 to 160 MeV at ambient temperature. The fluences were in the range from 1.0 × 1013 to 1.0 × 1015 ions/cm2. After irradiations, X-ray diffractometry (XRD) measurements and cross sectional transmission electron microscope (TEM) observations were conducted. The XRD results indicate that in the initial stage of amorphization in single crystalline Al2O3, high-density Se causes the formation of new planes and disordering. The new distorted lattice planes formed in the early stage of irradiation around the fluence of 5.0 × 1013 ions/cm2 for single crystalline Al2O3 irradiated with 160 MeV-Xe ions. Energy dependence on structural modification was also examined in single crystalline Al2O3 irradiated by swift heavy ions. The XRD results indicate that the swift heavy ion irradiation causes the lattice expansion and the structural modification leading to amorphization progresses above the energy around 100 MeV in this XRD study. The TEM observations demonstrated that amorphization was induced in surface region in single crystalline Al2O3 irradiated by swift heavy ions above the fluence expected from the results of XRD. Obvious boundary was observed in the cross sectional TEM images. The crystal structure of surface region above the boundary was identified to be amorphous and deeper region to be single crystal. The threshold fluence of amorphization was found to be around 1.0 × 1014 ions/cm2 in the case over 80 MeV swift heavy ion irradiation and the fluence did not depend on the crystal structures.

Okubo, N.; Ishikawa, N.; Sataka, M.; Jitsukawa, S.

2013-11-01

55

Zn nanoparticles irradiated with swift heavy ions at low fluences: Optically-detected shape elongation induced by nonoverlapping ion tracks  

SciTech Connect

Elongation of metal nanoparticles (NPs) embedded in silica (SiO{sub 2}) induced by swift heavy-ion (SHI) irradiation, from spheres to spheroids, has been evaluated mainly by transmission electron microscopy (TEM) at high fluences, where tens to thousands of ion tracks were overlapped each other. It is important to clarify whether the high fluences, i.e., track overlaps, are essential for the elongation. In this study the elongation of metal NPs was evaluated at low fluences by linearly polarized optical absorption spectroscopy. Zn NPs embedded in silica were irradiated with 200-MeV Xe{sup 14+} ions with an incident angle of 45 deg. The fluence ranged from 1.0x10{sup 11} to 5.0x10{sup 13} Xe/cm{sup 2}, which corresponds to the track coverage ratio (CR) of 0.050 to 25 by ion tracks. A small but certain dichroism was observed down to 5.0x10{sup 11} Xe/cm{sup 2} (CR = 0.25). The comparison with numerical simulation suggested that the elongation of Zn NPs was induced by nonoverlapping ion tracks. After further irradiation each NP experienced multiple SHI impacts, which resulted in further elongation. TEM observation showed the elongated NPs whose aspect ratio (AR) ranged from 1.2 to 1.7 at 5.0x10{sup 13} Xe/cm{sup 2}. Under almost the same irradiation conditions, Co NPs with the same initial mean radius showed more prominent elongation with AR of {approx}4 at the same fluence, while the melting point (m.p.) of Co is much higher than that of Zn. Less efficient elongation of Zn NPs while lower m.p. is discussed.

Amekura, H.; Mitsuishi, K.; Nakayama, Y.; Kishimoto, N. [National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba, Ibaraki 305-0003 (Japan); Ishikawa, N.; Okubo, N. [Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki (Japan); Ridgway, M. C.; Giulian, R. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra (Australia); Buchal, Ch.; Mantl, S. [Institut fuer Bio- und Nanosysteme (IBN1-IT), Forschungszentrum Juelich GmbH, D-52425, Juelich (Germany)

2011-05-15

56

The formation of new phase and chemical bonds in N-doped diamond films induced by swift heavy ion irradiation  

Microsoft Academic Search

In this paper, the formation of the new phase and chemical bonds in N-doped diamond films after swift heavy ion irradiations was studied. The original samples were diamond films grown on (111) oriented p-Si by CVD deposition. These samples were implanted with 100 keV N-ions at room temperature to 5×1017, 1×1018 and 5×1018 N\\/cm2, irradiated with 345 MeV Xe or

Z. G. Wang; Z. M. Zhao; Y. Song; J. Liu; Y. M. Sun; C. H. Zhang; J. L. Duan; Y. F. Jin

2004-01-01

57

Study on effects of swift heavy ion irradiation in cerium dioxide using synchrotron radiation X-ray absorption spectroscopy  

Microsoft Academic Search

In order to simulate the effects of high energy fission products on high-burnup UO2 nuclear fuel pellets, CeO2 thin films and bulk specimens were irradiated with 200MeV Xe ions. Effects of the irradiation were studied by using Extended X-ray Absorption Fine Structure (EXAFS) measurement and X-ray photoelectron spectroscopy (XPS) at synchrotron radiation facilities. The EXAFS spectra for the irradiated thin

H. Ohno; A. Iwase; D. Matsumura; Y. Nishihata; J. Mizuki; N. Ishikawa; Y. Baba; N. Hirao; T. Sonoda; M. Kinoshita

2008-01-01

58

Low energy Xe + ion beam machining of ULE® substrates for EUVL projection optics – Evaluation of high-spatial frequency roughness  

Microsoft Academic Search

Ion beam figuring (IBF) is a suitable technology for the final shape correction of substrates used in the projection optics of EUVL tools. In order to achieve HSFR below 0.10nm rms, we have conducted our research on ion beam machining of the ULE® substrate by Xe+ ion beam with energy less than 2keV. The HSFR of the unprocessed ULE® surface

Hironori Endo; Takuro Inaba; Shahjada A. Pahlovy; Iwao Miyamoto

2010-01-01

59

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

60

Surface Analysis of Ion Irradiated Amorphous Ribbon by GIXD and NEXAFS  

NASA Astrophysics Data System (ADS)

Recently a great increase of giant magneto impedance (GMI) ratio due to ion irradiation was found in the amorphous ribbon and intensive research into this mechanism will result in a technological importance in the field of sensor applications. The mechanism of the abrupt increase of GMI ratio by ion irradiation was not identified yet. The samples used in the present study were commercial amorphous ribbons of Co66Fe4B15Si15, in the size of 2 mm × 40 mm × 20?m. Various kinds of ions such as N, Ar, and Xe have been irradiated with energy of 70 keV by an ion implanter and an ion dosage was set to 1.0×1016 ion/cm2 at a beam flux of 3.7 ?A/cm2. The grazing incident X-ray diffraction (GIXD) and near edge X-ray absorption fine structure (NEXAFS) experiments have been conducted in order to know the origin of abrupt increase of GMI ratio by ion irradiation. The GMI ratio was increased by about 6 times by an ion irradiation for the 1 MHz measuring frequency, and the change of the GMI ratio by an ion irradiation decreased with an increasing measuring frequency. The creation of crystalline phase and the new phase change were not observed from GIXD and NEXAFS experiments in case of Ar ion irradiation, but the drastic changes of the spectrum in the GIXD and NEXAFS experiment in case of Xe and N show that the crystalline phase and new phase change may affect the enhancement of GMI properties.

Park, D. G.; Angani, C. S.; Kim, G. D.; Kim, C. G.; Cheong, Y. M.

2011-01-01

61

Electronic and geometric structure of Ar+n and Xe+n clusters: The solvation of rare-gas ions by their parent atoms  

Microsoft Academic Search

Photoabsorption cross sections for Ar+n, 3<=n<=80, and Xe+n, 3<=n<=30 clusters have been measured. A single absorption maximum in the visible is observed for Ar+n, whose redshift with growing n is interpreted as a delocalization of the charge from a trimer to a tetramer ion. For Xe+3, two maxima, and for Xe+n, n>=5, three maxima are observed. For n>=5 the positive

Hellmut Haberland; Bernd von Issendorff; Thomas Kolar; Hans Kornmeier; Christoph Ludewigt; Andreas Risch

1991-01-01

62

Single- and double-electron processes in collisions of Xe{sup 23+} ions with helium  

SciTech Connect

We report the measurements of relative cross sections for single capture (SC), double capture (DC), single ionization (SI), double ionization (DI), and transfer ionization (TI) in collisions of Xe{sup 23+} ions with helium atoms in the velocity range of 0.65-1.32 a.u. The relative cross sections show a weak velocity dependence. The cross-section ratio of double- (DE) to single-electron (SE) removal from He, {sigma}{sub DE}/{sigma}{sub SE}, is about 0.45. Single capture is the dominant reaction channel which is followed by transfer ionization, while only very small probabilities are found for pure ionization and double capture. The present experimental data are in satisfactory agreement with the estimations by the extended classical over-barrier (ECB) model.

Ding Baowei; Wan Chengliang; Chen Shangwen [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Yu Deyang; Ruan Fangfang; Lu Rongchun; Cai Xiaohong [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); Shao Caojie [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China)

2010-09-15

63

Spectra of [ital L] x rays from fast highly charged Xe ions traveling in solids  

SciTech Connect

Spectra of [ital L] x rays emitted by 6- and 8-MeV/u Xe ions interacting with a variety of solid targets have been measured with a curved-crystal spectrometer. The spectra displayed an overall structure consisting of six strong peaks which were fairly well resolved for low-[ital Z] targets ([ital Z][sub 2]=3--6), but broadened into two featureless groups for higher-[ital Z] targets. The main components were identified as [ital L][alpha][sub 1] and [ital L][beta][sub 1] pairs associated with initial-state configurations having one to six [ital L]-shell vacancies. Detailed spectral analysis provided estimates of the average projectile charges and the average [ital L]- and [ital M]-electron populations [ital inside] the solids.

Horvat, V.; Watson, R.L.; Parameswaran, R. (Cyclotron Institute and Department of Chemistry, Texas A M University, College Station, Texas 77843 (United States))

1995-01-01

64

Preparation of ion-track membranes of poly(p-phenylene terephthalamide): Control of pore shape by irradiation with different ion beams  

NASA Astrophysics Data System (ADS)

The preparation of ion-track membranes of thermally stable poly(p-phenylene terephthalamide) (PPTA) was performed by ion beam irradiation followed by chemical etching with a sodium hypochlorite solution. Cylindrical pores were observed in the membrane irradiated with 197Au and 238U ions at an energy of 11.1 MeV/n. In contrast, funnel shape pores appeared in the membrane irradiated with 84Kr, 102Ru and 129Xe ion at energies of 6.2, 3.6 and 3.5 MeV/n, respectively. The 197Au and 238U ion irradiation was found to exhibit more than four times larger sensitivity to the track etching under the same etching conditions. Consequently, the pore shape can be controlled by the masses and energies of the irradiated ions, in close relation to the etching sensitivity of the track.

Suzuki, Yasuyuki; Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Voss, Kay-Obbe; Neumann, Reinhard; Yoshida, Masaru

2007-07-01

65

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

66

Thermal processes in multilayer second-generation HTSC under swift heavy-ion irradiation  

NASA Astrophysics Data System (ADS)

On the basis of the thermal spike model, the estimations with regard to tapes of the second-generation Ag/YBaCuO/MgO/Hastelloy HTSC under irradiation with Ar, Kr, and Xe ions of an energy of about 1.2 MeV/amu have been carried out. The results have been compared with the available experimental data. In addition, the possibility of processes such as melting, recrystallization, amorphization, and other phase transitions in multilayer structures under ion irradiation has been studied.

Didyk, A. Yu.; Semina, V. K.; Hofman, A.; Mikhailova, G. N.; Troitskij, A. V.; Antonova, L. Kh.

2013-09-01

67

Multiple electron capture and photon emission of slow highly charged Taq+ ions in collisions with He and Xe  

Microsoft Academic Search

Multiple electron capture and photon emission in slow (velocity v ~ 0.3 au) collisions by highly charged Taq+(q = 41-49) projectile ions and atomic targets of He and Xe were investigated. The absolute photon yield, or number of x-rays emitted from the projectile ion, showed considerably different behaviours in two distinctive regions of projectile charge state q: the closed M-shell

S. Madzunkov; D. Fry; R. Schuch

2004-01-01

68

Electron cyclotron resonance ion source related development work for heavy-ion irradiation tests  

SciTech Connect

The European Space Agency (ESA) uses the facilities at the Accelerator Laboratory (Department of Physics, University of Jyvaeskylae: JYFL) for heavy-ion irradiation tests of electronic components. Electron cyclotron resonance ion source related development work has been carried out in order to meet the requirements set by the project. During the irradiation tests several beam changes are performed during the day. Therefore, the time needed for the beam changes has to be minimized. As a consequence, a beam cocktail having nearly the same m/q ratio is used. This makes it possible a quick tuning of the cyclotron to select the required ion for the irradiation. In addition to this requirement, very high charge states for the heavy elements are needed to reach a penetration depth of 100 {mu}m in silicon. In this article we present some procedures to optimize the ion source operation. We also present results of the first three-frequency heating tests. The main frequency of 14 GHz was fed from a klystron and both secondary frequencies were launched from a traveling-wave tube amplifier (TWTA). Two separate frequency generators were used simultaneously to provide different signals for the TWTA. During the test an improvement of about 20% was observed for {sup 84}Kr{sup 25+} and {sup 129}Xe{sup 30+} ion beams when the third frequency was applied.

Koivisto, H.; Suominen, P.; Tarvainen, O.; Virtanen, A.; Parkkinen, A. [Department of Physics, University of Jyvaeskylae, P.O. Box. 35 (Y5), FIN-40014 Jyvaeskylae (Finland); Finnish Airforce C4IS MC, 41160, Tikkakoski (Finland)

2006-03-15

69

Swift heavy ion irradiation of Cu-Zn-Al and Cu-Al-Ni alloys  

Microsoft Academic Search

The effects produced by swift heavy ions in the martensitic (18R) and austenitic phase (beta) of Cu based shape memory alloys were characterized. Single crystal samples with a surface normal close to [210]18R and [001]beta were irradiated with 200 MeV of Kr15+, 230 MeV of Xe15+, 350 and 600 MeV of Au26+ and Au29+. Changes in the microstructure were studied

E. Zelaya; A. Tolley; A. M. Condo; G. Schumacher

2009-01-01

70

Improved field emission of electrons from ion irradiated carbon  

SciTech Connect

Electron field emission from allotropes of carbon (graphite, diamondlike carbon, and diamond) have been reported many times in the literature. This work explores the use of ion irradiation for improving electron field emission from carbon fibers. Carbon fibers have been irradiated with H, C, Ar, and Xe ions. Field emission characteristics have been measured as a function of ion dose. A reversible reduction in the required field for a fixed current level has been observed. The critical dose, D{sub c}, defines the dose corresponding to the lowest field necessary to emit a fixed current (5 {mu}A). The critical dose appears to correlate with the nuclear energy loss (collisions with atoms) of the ion in the carbon fiber. Transmission electron microscopy and parallel electron energy loss spectroscopy analysis indicate an amorphous surface, and an increase in the sp{sup 3} content of the fiber surface to 20{percent}{endash}30{percent}. A corresponding decrease in the work function is expected and may account for the improvement in electron emission. {copyright} {ital 1997 American Institute of Physics.}

Walter, K.C.; Kung, H.H.; Maggiore, C.J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1997-09-01

71

Advanced SiC fiber strain behavior during ion beam irradiation  

NASA Astrophysics Data System (ADS)

The in situ strain behavior upon ion beam irradiation of a Tyranno SA3 SiC fiber was investigated in real time. For this purpose, a tensile test device suitable for micrometrical samples was developed to allow studies in various irradiation facilities. A 7.44 ?m diameter SiC fiber was submitted to both low mechanical loading at 300 MPa and 92-MeV Xe ion beam irradiation at room temperature. The fiber exhibited a gradual increase of its longitudinal strain reaching a maximum value of 0.50% for a total fluence of 5 × 1014 ions cm?2. Raman spectroscopy analyses performed on fibers submitted to the same irradiation conditions have shown significant local structure modification but no evidence of amorphization.

Jankowiak, A.; Grygiel, C.; Monnet, I.; Serruys, Y.; Colin, C.; Miro, S.; Gelebart, L.; Gosmain, L.; Costantini, J.-M.

2013-11-01

72

The energy loss effects on the absorption edge of LiTaO3 irradiated by energetic heavy ions  

NASA Astrophysics Data System (ADS)

The z-cut LiTaO3 single crystals were irradiated by 6 MeV Xe-ion at the fluences in the range from 1.0 × 1012 to 1.0 × 1015 ions/cm2, or 30, 375, 1980 MeV Kr ions at the fluences in the range from 1.0 × 1011 to 1.0 × 1013 ions/cm2. The irradiated samples were analyzed by optical spectrometer and Rutherford backscattering-channeling spectroscopy. It was found that the UV absorption edge of LiTaO3 shifts toward to longer wavelength (red-shift) as a result of heavy-ion irradiation. In 6 MeV Xe-ion irradiated samples, the red-shifts are weak even at a high fluence of 1.0 × 1015 ions/cm2 when the irradiated layer becomes amorphous. However, in 30, 375, 1980 MeV Kr-ion irradiated samples, significant red-shifts were observed even at low fluences. The effects of nuclear energy loss and electronic energy loss on the red-shift of absorption edge in LiTaO3 are discussed.

Pang, L. L.; Wang, Z. G.; Sun, J. R.; Yao, C. F.; Wei, K. F.; Shen, T. L.; Cui, M. H.; Zhu, Y. B.; Sheng, Y. B.; Li, Y. F.; Chang, H. L.; Wang, J.; Zhu, H. P.

2013-07-01

73

Radioluminescence Investigation Of Ion-irradiated Phosphors  

SciTech Connect

Phosphors are materials that emit light under the excitation of incoming radiation. This property is used, among other applications, in radiation detection. Efficient energy transfer from the ionization track to the luminescent centers must occur to yield significant light output. Besides, the investigation of the effects of ion irradiation on the luminescence of phosphors is comparatively unexplored. In this work, we review radioluminescence (RL) investigation of ion-irradiated oxides and oxide phosphors, and present preliminary data on the effects of ion irradiation on the luminescence of intrinsic phosphor Bi{sub 4}Ge{sub 3}0{sub 12} (BGO). Commercial crystals were irradiated, and the irradiation effects characterized by means of RL measurements as a function of temperature, from 10K to room temperature (RT), and optical absorption measurements. Overall, surface modification induced by ion irradiation leads to higher luminescence output.

Jacobsohn, Luiz [Los Alamos National Laboratory; Muenchausen, Ross [Los Alamos National Laboratory; Bennett, Bryan [Los Alamos National Laboratory

2008-01-01

74

High energy heavy ion irradiation damage in yttrium iron garnet  

NASA Astrophysics Data System (ADS)

We have studied the damage in ferrimagnetic yttrium iron garnet, Y3Fe5O12 or YIG, produced by energetic heavy ion bombardment, for which the electronic stopping power is much higher than the nuclear stopping power. Epitaxial thin films of YIG on (111)-Gd3Ga5O12 substrates were thus irradiated at room temperature with 50 MeV 32S, 50 MeV 63Cu, 235 MeV 84Kr, and with 59 MeV, 185 MeV and 792 MeV 132Xe ion beams. The film thicknesses were always smaller than the ion mean projected ranges, in order to avoid implantation effects in the layers. The resulting damage was then studied by high resolution X-ray diffraction, channeling Rutherford backscattering (RBS) spectroscopy and room temperature magnetization measurements. After these ion irradiations, the structural as well as the ferrimagnetic long-range orders are progressively destroyed. X-ray measurements on 84Kr irradiated samples show the presence of compressive lateral macrostresses in the films due to the coexistence of crystalline and disordered phases. These stresses are partly relaxed away at high fluences, when the amount of disordered phase is high enough (around 45%). Cross section data for this damage process are deduced from the RBS and 300 K saturation magnetization measurements for six different values of the electronic energy loss, between 7 and 27 MeV ?m-1. The damage cross section increases nonlinearly as a function of the electronic stopping power, then seems to level off above 22 MeV ?m -1. However the comparison with previous works indicates that the electronic stopping power might not be the only key-parameter in this process, where the ion beam energy parameters might play some role.

Costantini, J. M.; Brisard, F.; Flament, J. L.; Meftah, A.; Toulemonde, M.; Hage-Ali, M.

1992-03-01

75

In situ RBS measurements for the effect of swift heavy ion irradiation on metal–insulator interfaces  

NASA Astrophysics Data System (ADS)

We have studied the effect of 200 MeV Xe ion irradiation on Bi–Al2O3 and Au–Al2O3 interfaces by means of in situ Rutherford backscattering spectrometry (RBS). For the Bi–Al2O3 interface, we could observe a systematic change in RBS spectrum as a function of Xe ion fluence or the irradiation time. On the other hand, for Au–Al2O3 system, we could not observe any change in RBS spectrum. The experimental result confirmed our previous result that atomic mixing at Bi–Al2O3 interface surely occurs by the Xe ion irradiation. We analyzed the RBS spectra by the simulation software SIMNRA, and discussed the Bi–Al2O3 mixing quantitatively. From the irradiation time dependence of the mixing layer thickness, we estimated the effective diffusion constant for the atomic mixing at Bi–Al2O3 interface. Its value corresponds to the self-diffusion near the melting temperature of Al2O3. The result implies that Bi and Al2O3 are in molten forms during the ion irradiation, resulting in the atomic mixing at Bi–Al2O3 interface.

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

2013-11-01

76

Direct observation of the Kr (3d-14p-1) and Xe (4d-15p-1) doubly charged ion states by threshold-photoelectron coincidence spectroscopy  

Microsoft Academic Search

Threshold-photoelectron coincidence spectra and threshold-photoelectron spectra are measured for Kr and Xe in the energy regions 105-127 and 75-100 eV, respectively. Kr2+ 3d-14p-1 and Xe2+ 4d-15p-1 doubly charged ion states are observed, and also Kr+ 3d-14p-1nl and Xe 4d-15p-1nl satellite states. To our knowledge, this is the first direct observation in electron spectroscopy of doubly charged ion states where one

P. Bolognesi; L. Avaldi; M. C. Lopes; G. Dawber; G. C. King; M. A. MacDonald; C. Villani; F. Tarantelli

2001-01-01

77

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

78

On the origin of anomalous ranges of 1.65 GeV 132Xe ions in Muscovite Mica  

Microsoft Academic Search

Ranges of 1.65 GeV 132Xe ions in muscovite mica, determined using solid state nuclear track detector (SSNTD) techniques, are shown to vary strongly with angle of incidence to the basal plane. This is explained within the framework of the Chadderton-Koul-Biersack (CKB) model for latent track formation in real crystals. Not only are there clear bursts of electronic energy loss at

Lewis T. Chadderton; S. Ghosh; A. Saxena; K. K. Dwivedi; Jochen P. Biersack; Dietmar W. Fink

1990-01-01

79

Surface nanostructuring of SrTiO 3 single crystals by slow highly charged ions and swift heavy ions  

Microsoft Academic Search

Single crystals of strontium titanate have been irradiated with both slow highly charged Xe ions extracted from an Electron Beam Ion Trap and swift heavy Xe ions. After irradiation, the crystals were investigated by scanning force microscopy in air. In both cases nanohillocks due to impact of individual projectiles were observed. This similarity originates from the fact that both swift

A. S. El-Said; R. A. Wilhelm; R. Heller; S. Facsko; C. Trautmann; F. Aumayr

2011-01-01

80

Electron-ion collision rates in noble gas clusters irradiated by femtosecond laser pulse  

NASA Astrophysics Data System (ADS)

We report a theoretical analysis of electron-ion collision rates in xenon gas clusters irradiated by femtosecond laser pulses. The present analysis is based on the eikonal approximation (EA), the first Born approximation (FBA) and the classical (CL) methods. The calculations are performed using the plasma-screened Rogers potential introduced by Moll et al. [J. Phys. B. 43, 135103 (2010)] as well as the Debye potential for a wide range of experimental parameters. We find that the magnitudes of electron-ion collision frequency obtained in the EA do not fall as rapidly with the kinetic energy of electrons as in the FBA and CL methods for higher charge states of xenon ion (Xe8+ and Xe14+). Furthermore, EA shows that the effect of the inner structure of ion is most dominant for the lowest charge state of xenon ion (Xe1+). In the case of the present effective potential, FBA overestimates the CL results for all three different charge states of xenon, whereas for the Debye potential, both the FBA and CL methods predict collision frequencies which are nearly close to each other.

Dey, R.; Roy, A. C.

2012-05-01

81

Low Energy Xe+ Ion Beam Machining of the Ultralow Expansion Glass Substrates for Aspherical Extreme Ultraviolet Lithography Projection Optics  

NASA Astrophysics Data System (ADS)

Aspherical substrates for extreme ultraviolet lithography (EUVL) optics require an ultrahigh shape accuracy of less than 0.15 nm rms and a high-spatial frequency roughness (HSFR; spatial wavelength: less than 1 ?m) of 0.12 nm rms. Generally, the ultra low expansion glass (ULE®) substrate with HSFR of 0.06--0.08 nm rms can be produced by mechanical machining methods. However, it is difficult to obtain the shape accuracy of less than 0.12 nm rms using mechanical machining methods. Therefore, ion beam figuring (IBF) may be adapted to final shape correction of the substrates for the projection optics of EUVL tools. In this study, we investigated the HSFR and machining rate of the ULE® substrate machined by a 0.3--1.0 keV Xe+ ion beam at off normal ion incidence angles and obtained the following results: the HSFRs of the ULE® substrate machined by a 1.0 keV Xe+ ion beam at a ion incidence angle of lower than 30° and a 0.3--0.5 keV Xe+ ion beam at an ion incidence angle of 0--45° are below 0.12 nm rms, which is smaller than the required HSFR specification of EUVL projection optics. From our experimental result and discussion, we concluded that the scan fine beam and tilt target mode smoothing for processing of the ULE® substrate meets the required specification of the HSFR (0.12 nm rms) of hemispherical ULE® substrates of EUVL projection optics.

Endo, Hironori; Yamada, Junya; Pahlovy, Shahjada A.; Miyamoto, Iwao

2011-06-01

82

Fragmentation of DNA components by hyperthermal heavy ion (Ar+ and Xe+) impact in the condensed phase  

NASA Astrophysics Data System (ADS)

The overriding environmental factor that presently limits human endeavors in space is exposure to heavy ion radiation. While knowledge of its damage to living tissue is essential for radiation protection and risk estimates for astronauts, very little data exists at the molecular level regarding the nascent DNA damage by the primary particle track, or by secondary species during subsequent reaction cascades. This persistent lack of a basic understanding of nascent damage induced by such low dose, high LET radiation, introduces unacceptable errors in radiation risk estimates (based mainly on extrapolation from high dose, low LET radiation), particularly for long term exposure. Mutagenic effects induced by heavy ion radiation to cells are largely due to DNA damage by secondary transient species, i.e. secondary ballistic ions, electrons and radicals generated along the ion tracks; the secondary ions have hyperthermal energies up to several 100 eV, which they will deposit within a few nm in the surrounding medium; thus their LET is very high, and yields lethal clustered DNA lesions. We present measurements of molecular damage induced in films of DNA components by ions with precisely such low energies (1-100 eV) and compare results to conventional electron impact measurements. Experiments are conducted in UHV using a mass selected low energy ion source, and a high-resolution quadrupole MS to monitor ion yields desorbing from molecular films. Among the major fragments, NH4 + is identified in the desorption mass spectra of irradiated films of Adenine, Guanine, Cytosine, indicating efficient deamination; in cells this results in pre-mutagenic lesions. Experiments with 5-amino-Uracil, and comparison to previous results on uracil and thymine show that deamination is a key step in the NH4 + fragment formation. For Adenine, we also observe formation of amine aducts in the films, viz. amination of Adenine, and global fragmentation in all ion impact mass spectra, attributed mainly to kinetic & potential ion scattering.[Funded by NSERC and the Canadian Space Agency].

Sarabipour, Sarvenaz; Sarvenaz Sarabipour, Ms; Michaud, Marc; Deng, Zongwu; Huels, Michael A.

83

Ion irradiation induced hollow and sandwiched nanoparticles  

SciTech Connect

We report on the fabrication of hollow and sandwiched nanoparticles by ion irradiation. Ag nanoparticles embedded in silica were irradiated by N{sup +}, Si{sup +}, Ar{sup +}, and Cu{sup +} ions at 300 keV to a fluence of 5x10{sup 16} ions/cm{sup 2}, by Cu{sup +} ions at varying energies from 110 to 500 keV to a fluence of 5x10{sup 16} ions/cm{sup 2}, and by Cu{sup +} ions at 400 keV to fluences varied from 1x10{sup 16} to 1x10{sup 17} ions/cm{sup 2}. The size of the irradiation-induced nanovoids increases with increasing ion mass and energy. The formation of nanovoids depends on the electronic and nuclear energy loss of the irradiation ions. The formation of irradiation-induced sandwiched nanoparticles is because of the capture of knocked-out Ag atoms from nanoshells by nanovoids. The size of the inner nanoparticles within the sandwiched structure increases with increasing fluence.

Ren Feng; Cai Guangxu; Xiao Xiangheng; Fan Lixia; Liu Chang; Fu Dejun; Wang Jianbo; Jiang Changzhong [Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Wuhan University, Wuhan 430072 (China) and Department of Physics, Wuhan University, Wuhan 430072 (China)

2008-04-15

84

Irradiation effect of swift heavy ion for Zr50Cu40Al10 bulk glassy alloy  

NASA Astrophysics Data System (ADS)

It has been reported that heavy ion irradiation causes softening in some cases of Zr-based bulk metallic glass alloys. However, the fundamental mechanisms of such softening have not been clarified yet. In this study, Zr50Cu40Al10 bulk glassy alloys were irradiated with heavy ions of 10 MeV I at room temperature. The maximum fluence was 3 × 1014 ions/cm2. The positron annihilation measurements have performed before and after irradiation to investigate changes in free volume. We discuss the relationship between the energy loss and local open volume change after 10 MeV I irradiation compared with those obtained for 200 MeV Xe and 5 MeV Al. The energy loss analysis in ion irradiation for the positron lifetime has revealed that the decreasing trend of positron lifetime is well expressed as a function of total electronic energy deposition rather than total elastic energy deposition. It means that the positron lifetime change by the irradiation has a relationship with the inelastic collisions with electrons during heavy ion irradiation.

Onodera, Naoto; Ishii, Akito; Ishii, Kouji; Iwase, Akihiro; Yokoyama, Yoshihiko; Saitoh, Yuichi; Ishikawa, Norito; Yabuuchi, Atsushi; Hori, Fuminobu

2013-11-01

85

Positron annihilation study of the hardening behavior in Al-Cu based alloy by electron and heavy ion irradiation  

NASA Astrophysics Data System (ADS)

Al-Cu based alloy, which is generally called duralumin (JIS2017), was irradiated with 10 MeV Iodine ions, 200 MeV Xenon ions and 3 MeV electrons at room temperature respectively. The micro Vicker's hardness and positron annihilation coincidence Doppler broadening (CDB) measurements have been performed before and after irradiation. Only in the case of ion irradiation, the Vicker's hardness increases with increasing ion dose. Nevertheless, there was no difference in the profile CDB spectrum for before and after irradiation. On the other hand, we found that the micro hardness of this alloy, which was Xe ion irradiated and subsequently annealed at 423 K, is greater than that of age hardened alloy without irradiation. CDB ratio curve of the age hardened Duralumin is clearly different in the electron momentum range around 0.015-0.025 mc from that of the ion irradiated alloy. The results of three-dimensional atom probe (3DAP) also show that a lot of small clusters were found after ion irradiation but large precipitations have found in annealed Duralumin. These results reveal that a number of small clusters formed in this alloy after ion irradiation, and they should strongly affects the micro hardness.

Hori, Fuminobu; Kobayashi, Ippei; Saito, Yuichi; Ishikawa, Norito; Oshima, Takeshi; Iwase, Akihiro

2010-04-01

86

In situ observation of defect growth beyond the irradiated region in yttria-stabilized zirconia induced by 400 keV xenon ion-beam at -90 and 30{degrees}C  

SciTech Connect

Single crystals of yttria-stabilized zirconia were irradiated with 400 keV Xe ion-beam at room temperature and minus 90 degrees centigrade. Defect growth was monitored in situ with Rutherford Backscattering and ion channeling techniques using a 2 MeV He ion beam.

Yu, N.; Sickafus, K.E.; Kodali, P.; Nastasi, M.

1996-04-01

87

Multiple electron capture and photon emission of slow highly charged Taq+ ions in collisions with He and Xe  

NASA Astrophysics Data System (ADS)

Multiple electron capture and photon emission in slow (velocity v ~ 0.3 au) collisions by highly charged Taq+(q = 41-49) projectile ions and atomic targets of He and Xe were investigated. The absolute photon yield, or number of x-rays emitted from the projectile ion, showed considerably different behaviours in two distinctive regions of projectile charge state q: the closed M-shell region (q < 45) and the open M-shell region (q > 45). We find that for a closed Ta M shell, in the case of He but not Xe, the absolute photon yield is smaller when two electrons are captured than in the case of single electron capture. For an open Ta M shell it is the opposite for both atomic targets. The branching ratios between three processes, radiative stabilization, internal dielectronic excitation (IDE) and Auger transition, are understood to have a critical influence on these different behaviours. Furthermore, it is found that these branching ratios are strongly influenced by the states into which electrons are captured, thus by the target atom species, and by the projectile core configuration. From our measurement of absolute photon yields for different capture channels, we derived the Auger probabilities after capture from He and Xe to be 0.5(2) and 0.7(2), respectively. We investigated multiple capture in the case of Xe when more than six electrons are transferred in the collision. A simple relation for the increase of the photon yield with increasing number of captured electrons is given.

Madzunkov, S.; Fry, D.; Schuch, R.

2004-08-01

88

Photoionization Cross Section of Xe{sup +} Ion in the Pure 5p{sup 5} {sup 2}P{sub 3/2} Ground Level  

SciTech Connect

Coupling an ion trap with synchrotron radiation is shown here to be a powerful approach to measure photoionization cross sections on ionic species relaxed in their ground state. The photoionization efficiency curve of Xe{sup +} ions stored in a Fourier transform ion cyclotron resonance ion trap was recorded at ELETTRA in the 20-23 eV photon energy range. Absolute cross sections were derived by comparison of the photoionization yield of Xe{sup +} with measurements from the ASTRID merged-beam experiment. Multiconfiguration Dirac-Fock calculations were performed for the interpretation of these new data.

Thissen, R. [Laboratoire de Planetologie de Grenoble, UMR 5109 du CNRS, Batiment D de Physique, B.P. 53, 38041 Grenoble (France); Bizau, J. M. [Laboratoire d'Interaction des Rayons X avec la Matiere (LIXAM), UMR 8624 du CNRS, Universite Paris-Sud, Batiment 350, 91405 Orsay cedex (France); Blancard, C. [CEA DAM Ile-de-France, DPTA, Bruyeres-le-Chatel, 91297 Arpajon Cedex (France); Coreno, M. [CNR-IMIP, Rome Branch, c/o GasPhase Beamline, Sincrotrone Trieste, I- 34012 Basovizza, Trieste (Italy); Dehon, C.; Lemaire, J. [Laboratoire de Chimie Physique, UMR 8000 du CNRS, Universite Paris-Sud, Batiment 350, 91405 Orsay cedex (France); Franceschi, P. [Sincrotrone Trieste, SS-14 in Area Science Park, I-34012 Basovizza, Trieste (Italy); Giuliani, A. [Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, B.P. 48, 91192 Gif-sur-Yvette (France); Cepia, Institut National de la Recherche Agronomique (INRA), B.P. 71627, 44316 Nantes Cedex 3 (France); Nicolas, C. [Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, B.P. 48, 91192 Gif-sur-Yvette (France)

2008-06-06

89

Thermo-physical, -mechanical, and -electrical behaviors of ion-irradiated Tyranno-SA SiC fibers at high temperatures (1473 K)  

NASA Astrophysics Data System (ADS)

The macro-properties of ion-irradiated Tyranno-SA SiC fibers have been studied. The fibers were irradiated at the National Large Accelerator of Heavy Ions facility, GANIL (Caen, France), under 95 MeV Xe ions at room temperature. Fibers were irradiated on two sides with two fluence levels to prevent damage gradients within the fibers. The behaviors of the ion-irradiated fibers at high temperatures (i.e., 303-1473 K) were analyzed using the specific tensile test device for a single fiber, referred to as MacaSiC. The thermo-properties regarding deformation, elastic modulus, and electrical conductivity of the ion-irradiated fibers showed specific behaviors with irreversibility, which implied the recovery of defects induced by ion-irradiation.

Shimoda, Kazuya; Colin, Christian

2013-11-01

90

Swift Heavy Ion Irradiation of Cobalt Nanoparticles  

Microsoft Academic Search

It is well known that the electronic energy loss released by swift heavy ions can cause considerable atomic movement in various solids. Here, we present a study of the effects of swift heavy ion irradiation on Co nanoparticles embedded within a silica host matrix. The evolution of the Co nanoparticle crystal phase, structural properties, shape and size has been characterized

D. J. Sprouster; R. Giulian; C. S. Schnohr; P. Kluth; L. L. Araujo; A. P. Byrne; G. J. Foran; M. C. Ridgway

2009-01-01

91

Multiple electron transfer in slow collisions of very high-charged Xe-ions and atoms  

SciTech Connect

We have measured absolute cross sections for processes of one and multi-electron capture in slow (0.1--0.2 a.u.) Xe[sup q+]-Xe collisions in the charge state regime 15[le]q[le]37. The transfer of two to six electrons from the target to the projectile, where two electrons stay on the projectile after deexcitation is studied. We find that the probability for keeping two electrons on the projectile (i.e. radiative stabilization of two electrons) increases rapidly with q and with the number of electrons initially transferred.

Biedermann, C.; Cederquist, H.; Selberg, N. (Manne Siegbahn Institute of Physics, S-10405 Stockholm (Sweden)); Hutton, R. (Manne Siegbahn Institute of Physics, S-10405 Stockholm (Sweden) University of Lund, S-22362 Lund (Sweden)); Levin, J.C. (Manne Siegbahn Institute of Physics, S-10405 Stockholm (Sweden) The University of Tennessee, Knoxville, Tennessee 37996-1200 (United States)); Beebe, E.; Liljeby, L.; Engestroem, A. (Manne Siegbahn Institute of Physics, S-10405 Stockholm (Sweden))

1993-06-05

92

Heavy Ions Irradiation of Untwinned Single Crystals of YBa_2Cu_3O_7  

NASA Astrophysics Data System (ADS)

Vortex pinning is studied in single crystals of YBa_2Cu_3O7 before and after irradiation with heavy ions. The crystals were irradiated with U, Au, or Xe ions. We will present the effects on the critical current density and pinning energies determined from both magnetic hysteresis and electrical transport measurements. We discuss the dose and ion size dependence of the effects. A discussion of these results in terms of the Bose-glass phase will be given. This work was supported by the U.S. DOE, BES-Materials Science contract #W-31-109-ENG-38(AMP, LMP, WKK, DD, GWC, BG), by the NSF-Science and Technology Center for Superconductivity contract #DMR91-20000(JAF) and by the NSF contract #PHY-9528844(RMR) (DD present address: Physics Department, University of Wisconsin, Milwaukee, JAF present address: 313 Microelectronics, 208 N. Wright Street, University of Illinois, Urbana IL, 61801)

Petrean, A. M.; Paulius, L. M.; Kwok, W. K.; Dasgupta, D.; Fendrich, J. A.; Crabtree, G. W.; Ronningen, R. M.; Glagola, B.

1997-03-01

93

New neutron-rich 179Yb and 181,182Lu isotopes produced in reactions of 9 MeV/u 136Xe ions on tantalum and tungsten targets  

NASA Astrophysics Data System (ADS)

The new neutron-rich isotopes 179Yb and 181,182Lu were produced in multinucleon transfer reactions by irradiating natW/Ta targets with 9 MeV/u 136Xe ions, and identified by mass separation and decay spectroscopy. The measured half-lives of 179Yb, 181Lu and 182Lu are 8.1±0.8, 3.5±0.3 and 2.0±0.2 min, respectively. The properties of the excited states of 181,182Hf are discussed. The possibility of studying neutron-rich nuclei outside the classical fission-product regions is demonstrated.

Kirchner, R.; Klepper, O.; Kurcewicz, W.; Roeckl, E.; Zganjar, E. F.; Runte, E.; Schmidt-Ott, W.-D.; Tidemand-Petersson, P.; Kaffrell, N.; Peuser, P.; Rykaczewski, K.

1982-04-01

94

Polarization analysis of fluorescence probing the alignment of Xe+ ions in the resonant Auger decay of the Xe* 4d-15\\/26p photoexcited state  

Microsoft Academic Search

Xe II fluorescence, following the resonant Auger decay of the Xe* 4d-15\\/26p photoexcited state, has been measured in the wavelength region 400 nm <=lambda (fluo) <=610 nm by means of dispersed fluorescence spectroscopy, and the degree of linear polarization of the emitted light has been analyzed. From these data, the alignment of the ionic 5p46p states produced by the Auger

M. Meyer; A. Marquette; A. N. Grum-Grzhimailo; U. Kleiman; B. Lohmann

2001-01-01

95

Effects of Ion Irradiation on Ice Porosity  

NASA Astrophysics Data System (ADS)

Vapor-deposited water ice is believed to be present in astronomical environments such as interstellar grains, planetary rings, comets, and icy satellites. Some salient properties are its amorphous molecular structure and its microporosity, which determines its capacity to absorb gas. Since in most astronomical environments these ices are subject to radiation it is important to determine the effect of radiation on porosity. We have studied in the laboratory the effects of ion irradiation on the porosity of amorphous ice using ultraviolet-visible spectroscopy and infrared spectroscopy. Our findings indicate that ion irradiation compacts porous ice. The density of the ice film rises asymptotically to a saturation value with increasing ion fluence. Irradiation also decreases the intensity of the ~ 2.7 ?m absorption features assigned to the O-H stretch of dangling molecules present in porous ice film. However, we find that the dangling bond features decrease at a faster rate than the ice porosity. To investigate this contrasting behavior, we performed gas adsorption/desorption experiments on ice films irradiated to different fluences of 100 keV Ar+ ions. We will discuss how these measurements can be used to obtain pore size distributions and changes induced via ion irradiation. Finally, our results open the possibility that ices can remain porous, even if the dangling bond features are not present, which is of particular interest in colder regions such as interstellar ices.

Raut, U.; Teolis, B. D.; Loeffler, M. J.; Fama, M.; Vidal, R. A.; Baragiola, R. A.

2006-05-01

96

3-10 keV Xe+ ion beam machining of ultra low thermal expansion glasses for EUVL projection optics: Evaluation of surface roughness  

NASA Astrophysics Data System (ADS)

In order to obtain surface figure error of 0.15 nm rms and surface roughness (Rrms) of 0.12 nm rms for aspherical substrates in EUVL tools, ion beam figuring may be adopted to final surface figure error correction of aspherical substrates. During figure error correction, machined surface of the substrate becomes rougher than the pre-finished one. Therefore, we investigated the machined depth and ion energy dependences of Rrms (measured by an AFM) of substrates machined by 3-10 keV Xe+ ion beam, and compared them with the results obtained for Ar+ ion beam. Result shows that the R of CLEARCERAM®-Z, Zerodur® and ULE® substrates machined to the depth of 50 nm by 3-10 keV Xe+ ion beam at the normal ion incidence angle become approximately 0.25, 0.28 and 0.15 nm rms, respectively. Those values are larger than the pre-finished substrates (0.07-0.09 nm rms), but smaller than that (0.60 nm rms for CLEARCERAM®-Z, 0.61 nm rms for Zerodur® and 0.18 nm rms for ULE®) of the substrates machined by Ar+ ion beam. Moreover, the R merely increase with increasing ion energy. The R of the ULE® substrate machined by 3-10 keV Xe+ ion beam rapidly increase with increasing machined depth, then saturate at machined depth of 10-50 nm. The saturated values of the R are 0.12 and 0.15 nm rms for 3 and 10 keV Xe+ ion beam respectively. We suggest that the 3 keV Xe+ ion beam machining can be applicable for final shape correction of ULE® substrates for EUVL projection optics in association with considering further ultra smoothing process such as Si deposition or low energy ion beam smoothing.

Morikawa, K.; Kamijo, K.; Morijiri, K.; Pahlovy, S. A.; Aikawa, N.; Miyamoto, I.

2012-02-01

97

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

98

Heavy ion irradiation of astrophysical ice analogs  

NASA Astrophysics Data System (ADS)

Icy grain mantles consist of small molecules containing hydrogen, carbon, oxygen and nitrogen atoms (e.g. H2O, CO, CO2, NH3). Such ices, present in different astrophysical environments (giant planets satellites, comets, dense clouds, and protoplanetary disks), are subjected to irradiation of different energetic particles: UV radiation, ion bombardment (solar and stellar wind as well as galactic cosmic rays), and secondary electrons due to cosmic ray ionization of H2. The interaction of these particles with astrophysical ice analogs has been the object of research over the last decades. However, there is a lack of information on the effects induced by the heavy ion component of cosmic rays in the electronic energy loss regime. The aim of the present work is to simulate of the astrophysical environment where ice mantles are exposed to the heavy ion cosmic ray irradiation. Sample ice films at 13K were irradiated by nickel ions with energies in the 1-10 MeV/u range and analyzed by means of FTIR spectrometry. Nickel ions were used because their energy deposition is similar to that deposited by iron ions, which are particularly abundant cosmic rays amongst the heaviest ones. In this work the effects caused by nickel ions on condensed gases are studied (destruction and production of molecules as well as associated cross sections, sputtering yields) and compared with respective values for light ions and UV photons.

Duarte, Eduardo Seperuelo; Domaracka, Alicja; Boduch, Philippe; Rothard, Hermann; Balanzat, Emmanuel; Dartois, Emmanuel; Pilling, Sergio; Farenzena, Lucio; da Silveira, Enio Frota

99

A new method of chlorophenols decomposition based on UV-irradiation by XeBr-excilamp and their subsequent biodegradation  

NASA Astrophysics Data System (ADS)

The combined decomposition method of chlorophenols (CP) is offered. The method is based on photolysis of CP through XeBr-excilamp UV irradiation at 283 nm in a flow photoreactor with subsequent treatment of photolysis products by microorganism-destructor B. cereus isolated from an aeration pond of Baikal pulp-and-paper mill. At initial concentration of CP of 20 mg/l the polluted solutions can be utilized directly by means of biological treatment using B. cereus under aerobic conditions. However, if the initial CP concentration is higher than 20 mg/l, the polluted solutions are low biodegradable. It is shown, that the combined treatment is most effective method in this case. At initial CP concentration of 50 mg/l and higher it is suggested to use the deep preliminary UV-treatment with the purpose of removal 80-90 % of initial CP. It is revealed, that 4-CP is relatively persistent compound for B. cereus, easily decomposed by UV-radiation of XeBr-excilamp. As a result of subsequent biological treatment during 10 days the utilization of basic CP photoproducts is obtained. Experimentally, the preliminary UV-processing time was essentially less than that found earlier by E. Tamer, Z. Hamid, Aly A. (Chemosphere, 2006), where the half-life periods of initial CP were from 2.2 to 54 hours at the same value of initial concentration of CP. Correspondingly, the total CP decomposition process was accompanied by high power inputs. It is suggested to use mentioned above method for effective CP decomposition at high concentration values.

Sosnin, E. A.; Matafonova, G. G.; Batoev, V. B.; Christofi, N.

2008-02-01

100

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

101

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

102

Electron-impact ionization and energy loss of 27-MeV/u Xe sup 35+ incident ions channeled in silicon  

SciTech Connect

We have measured the emerging charge-state distribution of 27-MeV/u Xe{sup 35+} beams channeled through a thin Si single crystal, and deduced electron impact ionization cross sections for Xe{sup 35+} to Xe{sup 45+} by 14.7-keV electrons. They are {approx}2 to 4 times higher than predicted by usually accepted empirical estimations. We have also measured the energy loss versus emerging charge state. For hyperchanneled Xe{sup {ital Q}+} ions, the stopping power depends only on the mean (and not on the actually sampled) density of valence electrons and compares well with the prediction of the electron gas model.

Andriamonje, S. (Centre d'Etudes Nucleaires de Bordeaux, Gradignan (France) Institut National de Physique Nucleaire et de Physique des Particules, Gradignan (France)); Anne, R.; de Castro Faria, N.V.; Chevallier, M.; Cohen, C.; Dural, J.; Gaillard, M.J.; Genre, R.; Hage-Ali, M.; Kirsch, R.; and others

1989-10-30

103

Ion irradiation-induced phase transformations in bixbyite-fluorite related oxides: The role of dislocation loop nucleation  

NASA Astrophysics Data System (ADS)

The ion irradiation induced phase transformations of bixbyite-fluorite related oxides have been studied with thin films of Y2O3 grown on Si and SrTiO3 by an ion beam sputtering technique which allows to control the microstructure and stresses within the film. Y2O3 thin films are ion-irradiated with an xenon beam in an energy range 60-380 keV at a fluence of 4.4 × 1015 Xe/cm2 at 80 K. Depending on the energy of the xenon beam two different structural phase transformations are observed: cubic to nanocrystalline/amorphous and cubic to monoclinic phase transformations. The phase transformation are analysed in terms of structural extended defect nucleation like prismatic dislocation loops due to the oxygen network behaviour under ion irradiation.

Gaboriaud, Rolly J.; Lacroix, Bertrand; Paumier, Fabien

2012-04-01

104

Electron irradiation effect on bubble formation and growth in a sodium borosilicate glass  

SciTech Connect

In this study, the authors studied simultaneous and intermittent electron irradiation effects on bubble growth in a simple sodium borosilicate glass during Xe ion implantation at 200 C. Simultaneous electron irradiation increases the average bubble size in the glass. This enhanced diffusion is also shown by the migration of Xe from bubbles into the matrix when the sample is irradiated by an electron beam after the Xe implantation.

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

2000-02-08

105

0.5 keV Xe + ion beam nano smoothing of ULE® substrate after processing with 3.0–10.0 keV Xe + ion beam  

Microsoft Academic Search

Ion beam figuring (IBF) is a suitable technology for the final shape correction of substrates used in the projection optics of EUVL tools. Generally the ULE® substrate with surface roughness of 0.060–0.080nm rms can be produced with mechanical machining methods. However, it is very difficult to obtain the shape accuracy of approximately 0.120nm rms using mechanical machining methods. Therefore, ion

K. Morijiri; H. Endo; K. Morikaawa; S. A. Pahlovy; I. Miyamoto

2011-01-01

106

Yield of 123 I in 124 Xe irradiation with protons in the 16–21.5 MeV energy range  

Microsoft Academic Search

Experimental Method. In order to determine the 123I yield as a function of the proton energy, we irradiated simultaneously six thin gaseous targets (16.6 mg\\/cm 2) containing 12~Xe enriched to 99.9% at a pressure of 120 kPa. The schematic of the target device is shown in Fig. i. The thin gaseous targets consist of nickel cylinders with an inside diameter

N. A. Konyakhin; V. N. Mironov; N. N. Krasnov; P. P. Dmitriev; V. P. Lapin; M. V. Panarin

1989-01-01

107

Deformation behavior of ion-irradiated polyimide  

SciTech Connect

We study nanoindentation hardness, Young's modulus, and tensile strength of polyimide (Kapton H) films bombarded with MeV light ions in the predominantly electronic stopping power regime. Results show that, for all the ion irradiation conditions studied, bombardment increases the hardness and Young's modulus and decreases the tensile strength. These changes depend close to linearly on ion fluence and superlinearly (with a power-law exponent factor of {approx}1.5) on electronic energy loss. Physical mechanisms of radiation-induced changes to mechanical properties of polyimide are discussed.

Kucheyev, S.O.; Felter, T.E.; Anthamatten, M.; Bradby, J.E. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Department of Electronic Materials Engineering, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, (Australia)

2004-08-02

108

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

109

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

110

Swelling in reactor-conditioned nickel-ion irradiated nimonic PE16. [Neutron irradiation and nickel-ion irradiation  

SciTech Connect

Nimonic PE16 solution treated and aged and neutron irradiated at three temperatures to a fluence up to 5.9 X 10/sup 22/ n/cm/sup 2/ was bombarded to an additional nominal nickel ion dose of 150 displacements per atom (dpa) at various temperatures. The swelling determined by transmission electron microscopy is described and comparisons are made with results obtained from ion bombardments of virgin material and high-fluence neutron irradiated material.

Bajaj, R.; Diamond, S.; Chickering, R.W.; Bleiberg, M.L.

1981-01-01

111

Critical appearance size of doubly charged Xe clusters revisited  

Microsoft Academic Search

In previous experiments on doubly charged Xe clusters, no Xe2+n cluster ions were observed for n less than 53 atoms and no Xe3+n for n less than 114 atoms. From recent computer simulations it was inferred that Xe2+51 ions have lifetimes ?100 ps while Xe2+55 ions have lifetimes ?10 ?s in agreement with these previous experimental results. Using a high

P. Scheier; G. Walder; A. Stamatovic; T. D. Märk

1989-01-01

112

An in situ TEM study of the evolution of Xe bubble populations in UO2  

NASA Astrophysics Data System (ADS)

Transmission electron microscopy (TEM) experiments were carried out on the JANNUS platform (Joint Accelerators for Nano-science and NUclear Simulation) at CSNSM (Center of Nuclear Spectrometry and Mass Spectrometry) laboratory in Orsay. The experiment was devoted to the study of the evolution of the xenon aggregate population with increasing implantation fluence. A thin UO2 foil was implanted at fluences ranging from 3 × 1012 to 7 × 1014 at cm-2 with 390 keV Xe3+ ions at an irradiation temperature of 873 K. The TEM results indicate the presence of nanometer size bubbles above a fluence of 6 × 1012 Xe cm-2 and an increase in the bubble number density was observed between 6 × 1012 Xe cm-2 and 2 × 1014 Xe cm-2. Above 2 × 1014 Xe cm-2, the number density levels off at 4 × 1023 ± 0.5 × 1023 m-3.

Michel, A.; Sabathier, C.; Carlot, G.; Kaïtasov, O.; Bouffard, S.; Garcia, P.; Valot, C.

2012-02-01

113

Comparison of (non)-sulfided NiNaY zeolite catalysts prepared by ion-exchange and impregnation by xenon adsorption and 129 Xe NMR  

Microsoft Academic Search

Ni2+ exchanged and NiCl2 impregnated non-sulfided and sulfided NaY zeolites were characterized by xenon adsorption isotherms,129 Xe NMR and thiophene hydrodesulfurization. The nickel species are located mainly inside the micropores of the zeolites in all samples. Ion-exchange results in a more homogeneous distribution of these species than impregnation. This explains their lower hydrodesulfurization activity compared to the ion-exchanged samples.

T. I. Korfinyi; L. J. M. van de Ven; W. J. J. Welters; J. W. de Haan; V. H. J. de Beer; R. A. van Santen

1993-01-01

114

Multiply charged cluster ions of Ar, Kr, Xe, N 2 , O 2 , CO 2 , SO 2 and NH 3 : Production mechanism, appearance size and appearance energy  

Microsoft Academic Search

Clusters of Ar, Kr, Xe, N2, O2, CO2, SO2 and NH3 formed by supersonic nozzle expansion have been studied by electron impact ionization mass spectrometry (up to 15000 amu). Besides mass spectra of singly charged ions showing the characteristic anomalous distributions, we have in particular investigated the properties of multiply charged cluster ions. Critical appearance sizes of doubly and triply

T. D. Märk; P. Scheier; M. Lezius; G. Walder; A. Stamatovic

1989-01-01

115

New material for low-dose brachytherapy seeds: Xe-doped amorphous carbon films with post-growth neutron activated 125I.  

PubMed

We report a novel material for use in (125)I brachytherapy that consists of amorphous carbon films grown by ion-beam-assisted deposition and doped with Xe (5 at%) by implantation. Samples of these films grown on Si substrates were irradiated with neutrons in a TRIGA-I nuclear reactor for the production (125)Xe, and latter characterized by gamma spectroscopy. The results indicate that the (124)Xe was efficiently converted into (125)Xe, the precursor of (125)I, and support the activity calculations for a model brachytherapy seed. PMID:20729094

Gonçalves, R G F; Pinheiro, M V B; Lacerda, R G; Ferlauto, A S; Ladeira, L O; Krambrock, K; Leal, A S; Viana, G A; Marques, F C

2010-08-12

116

Ultraviolet photodissociation of Xe+2 and Kr+2 1(12)u: Detection of rare-gas dimer ions in real time  

NASA Astrophysics Data System (ADS)

Momentary depletion of the Xe+2 (or Kr+2) 1(12)u population is observed by photodissociating the molecule at 351.1, 337.1, or 307.9 nm [on the 1(12)u-->2(12)g band] and monitoring the temporally resolved emission from the dissociative-recombination-fed neutral Xe line at 828.0 nm (6p[12]0-->6s[32]1). Near total suppression (>90%) of the Xe (6p-->6s) fluorescence is obtained for laser intensities of 50 MW cm-2. Measurements of the absolute electron density confirm that this effect is due to depletion of the dimer-ion concentration rather than photoionization of the 6p[12]0 state. However, photoionization of the Xe (6s' or 6p) levels is observed and the cross section is measured to be 2.3×10-18 cm2 at 351 nm. These experiments demonstrate a means for studying the collisional kinetics of rare-gas dimer ions in real time and in the presence of large background gas pressures.

McCown, A. W.; Ediger, M. N.; Stazak, S. M.; Eden, J. G.

1983-09-01

117

Microstructure and atomic disordering of magnesium aluminate spinel irradiated with swift heavy ions  

NASA Astrophysics Data System (ADS)

We have investigated the microstructure and atomic disordering of nearly stoichiometric magnesium aluminate spinel (MgO · 1.1Al2O3), irradiated with 200 MeV Xe14+ ions (Se = 25 keV/nm). Transmission electron microscopy techniques of bright-field (BF) and high-resolution (HR) imaging, as well as high angular resolution electron channeling X-ray spectroscopy (HARECXS) were employed for quantitative analysis of radiation-induced structural change. BF images of ion tracks show columnar dark contrast of ˜4 nm in diameter accompanying distinct black or white dots at the incident surface. Clear lattice fringes are observed in HR images even inside the ion tracks, indicating that the spinel crystals are not amorphized but partially disordered along the ion tracks. HARECXS analysis showed that cation disordering progresses successively with ion fluence, and the disordered regions are found to extend over 12.8 ± 0.9 nm in diameter for Al ions and 9.6 ± 0.6 nm for Mg ions along the ion tracks. This chemically disordered region is much larger than the strained volume detected by BF and HR images.

Yamamoto, T.; Shimada, M.; Yasuda, K.; Matsumura, S.; Chimi, Y.; Ishikawa, N.

2006-04-01

118

Study of local crystallization induced in FeSiNbZrB amorphous alloy by swift heavy ion (SHI) irradiation at room temperature  

NASA Astrophysics Data System (ADS)

Amorphous FeSiNbZrB alloy (metallic glass) ribbons were prepared by melt spinning and swift heavy ion (SHI) irradiation experiments were performed on the materials research terminal of the 320 kV ECR platform at the Institute of Modern Physics (IMP), Lanzhou. XRD, TEM and Mössbauer spectroscopy was used to reveal the irradiation-induced local crystallization, plastic deformation, damages and the magnetic moments rearrangements. The dimensions of our ribbons perpendicular to ion beam direction increased slightly , but the ribbon dimension along the ion beam shrunk; Irradiation of Xe-ions could cause local crystallization of amorphous FeSiNbZrB alloy ribbons and form finer ?-Fe(Si) phases precipitations with diameter of 1-2 nm; SHI irradiation could make the distribution of the magnetic moments of amorphous ribbons change their orientation from the in-plane orientation to the perpendicular one.

Sun, Jianrong; Wang, Zhiguang; Wang, Yuyu; Chang, Hailong; Song, Peng; Shen, Tielong; Zhu, Yabin; Pang, Lilong; Li, Fashen

2013-07-01

119

Energy transfer mechanisms and the radiation chemistry of noble gas ion irradiated polymers  

NASA Astrophysics Data System (ADS)

A number of selected polymers have been irradiated with noble gas ions and investigated by optical microscopy, nuclear particle track chemical etching, absorption spectroscopy in both the visible and infrared, and by electron spin resonance (ESR). Parameters systematically varied included the projectile species (He+, Ne+, Ar+ and Xe+ ions), the energy of bombardment (25 keV to 2 MeV), and the total dose, or fluence (1 × 1011 up to 3 × 1016 ions/cm2) A consolidated picture is built up of a radiation damaging process which is in general dominated by direct nuclear collisions between incident ions and carbon atoms in the polymeric chain. The most immediate formation of many new compounds is therefore vested in the physics and has little to do with any primary radiochemical process. Brief speculation is made on the formation of free radicals and carbon double bonding. Whereas electronically generated defects tend to recombine in Kapton easily, they play a dominant role in shaping the surface topography of irradiated Teflon. Even for doses as high as 3 × 1016 ions/cm2 the fundamental radiation effects have still not saturated. Highly doped polymers clearly behave distinctly different from carbon itself.

Koul, S. L.; Campbell, I. D.; McDonald, D. C.; Chadderton, Lewis T.; Fink, D.; Biersack, J. P.; Müller, M.

1988-05-01

120

Study on effects of swift heavy ion irradiation on the crystal structure in CeO 2 doped with Gd 2O 3  

Microsoft Academic Search

To simulate the effects of Gd2O3-doping and high-energy fission products in UO2, Gd2O3-doped CeO2 pellets were irradiated with 200-MeV Xe14+ ions. Doping and irradiation effects were analyzed using X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS). The lattice constant of CeO2 decreases and the local structure is disordered with increased doping levels. However, the irradiation induces an expansion

Y. Tahara; B. Zhu; S. Kosugi; N. Ishikawa; Y. Okamoto; F. Hori; T. Matsui; A. Iwase

2011-01-01

121

Defect formation and accumulation in CeO2 irradiated with swift heavy ions  

NASA Astrophysics Data System (ADS)

We have investigated microstructure evolution in CeO2 irradiated with 210 MeV Xe ions by using transmission electron microscopy to gain the fundamental knowledge on radiation damage induced by fission fragments in nuclear fuel and transmutation target. Analysis on the accumulation of ion tracks has revealed an influence region to recover pre-existing core damage regions of ion tracks to be 8.4 nm in radius. Cross section observations showed that high-density electronic excitation induces both ion tracks and dislocation loops. At high fluences of 1.5 × 1019 and 1 × 1020 ions m?2, depth-dependent microstructure was developed with radiation-induced defects of ion tracks, dislocation loops (dot-contrast) and line dislocations. Formation of sub-divided small grains was found at shallow depth at a fluence of 1 × 1020 ions m?2. The microstructure evolution was discussed in terms of the accumulation of interstitials due to significant overlap of high density electronic excitation.

Yasuda, K.; Etoh, M.; Sawada, K.; Yamamoto, T.; Yasunaga, K.; Matsumura, S.; Ishikawa, N.

2013-11-01

122

Hydrogen retention in ion irradiated steels  

SciTech Connect

In the future 1--5 MW Spallation Neutron Source, target radiation damage will be accompanied by high levels of hydrogen and helium transmutation products. The authors have recently carried out investigations using simultaneous Fe/He,H multiple-ion implantations into 316 LN stainless steel between 50 and 350 C to simulate the type of radiation damage expected in spallation neutron sources. Hydrogen and helium were injected at appropriate energy and rate, while displacement damage was introduced by nuclear stopping of 3.5 MeV Fe{sup +}, 1 {micro}m below the surface. Nanoindentation measurements showed a cumulative increase in hardness as a result of hydrogen and helium injection over and above the hardness increase due to the displacement damage alone. TEM investigation indicated the presence of small bubbles of the injected gases in the irradiated area. In the current experiment, the retention of hydrogen in irradiated steel was studied in order to better understand its contribution to the observed hardening. To achieve this, the deuterium isotope ({sup 2}H) was injected in place of natural hydrogen ({sup 1}H) during the implantation. Trapped deuterium was then profiled, at room temperature, using the high cross-section nuclear resonance reaction with {sup 3}He. Results showed a surprisingly high concentration of deuterium to be retained in the irradiated steel at low temperature, especially in the presence of helium. There is indication that hydrogen retention at spallation neutron source relevant target temperatures may reach as high as 10%.

Hunn, J.D.; Lewis, M.B.; Lee, E.H.

1998-11-01

123

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

124

Kinetic energy distribution of multiply charged ions in Coulomb explosion of Xe clusters  

NASA Astrophysics Data System (ADS)

We report on the calculations of kinetic energy distribution (KED) functions of multiply charged, high-energy ions in Coulomb explosion (CE) of an assembly of elemental Xen clusters (average size = 200-2171) driven by ultra-intense, near-infrared, Gaussian laser fields (peak intensities 1015 - 4 × 1016 W cm-2, pulse lengths 65-230 fs). In this cluster size and pulse parameter domain, outer ionization is incomplete/vertical, incomplete/nonvertical, or complete/nonvertical, with CE occurring in the presence of nanoplasma electrons. The KEDs were obtained from double averaging of single-trajectory molecular dynamics simulation ion kinetic energies. The KEDs were doubly averaged over a log-normal cluster size distribution and over the laser intensity distribution of a spatial Gaussian beam, which constitutes either a two-dimensional (2D) or a three-dimensional (3D) profile, with the 3D profile (when the cluster beam radius is larger than the Rayleigh length) usually being experimentally realized. The general features of the doubly averaged KEDs manifest the smearing out of the structure corresponding to the distribution of ion charges, a marked increase of the KEDs at very low energies due to the contribution from the persistent nanoplasma, a distortion of the KEDs and of the average energies toward lower energy values, and the appearance of long low-intensity high-energy tails caused by the admixture of contributions from large clusters by size averaging. The doubly averaged simulation results account reasonably well (within 30%) for the experimental data for the cluster-size dependence of the CE energetics and for its dependence on the laser pulse parameters, as well as for the anisotropy in the angular distribution of the energies of the Xeq+ ions. Possible applications of this computational study include a control of the ion kinetic energies by the choice of the laser intensity profile (2D/3D) in the laser-cluster interaction volume.

Heidenreich, Andreas; Jortner, Joshua

2011-02-01

125

Optical alteration of complex organics induced by ion irradiation  

Microsoft Academic Search

Most ion irradiation experiments relevant to primitive outer Solar System objects have been performed on ice and silicate targets. Here we present the first ion irradiation experiments performed on natural complex hydrocarbons (asphaltite and kerite). These materials are very dark in the visible and have red-sloped spectra in the visible and near-infrared. They may be comparable in composition and structure

Lyuba Moroz; Giuseppe Baratta; Giovanni Strazzulla; Larissa Starukhina; Elisabetta Dotto; Maria Antonietta Barucci; Gabriele Arnold; Elisa Distefano

2004-01-01

126

Si+ ion irradiation in a Co/Pt multilayer system  

NASA Astrophysics Data System (ADS)

This paper deals with a study of the effect of Si+ ion irradiation on a Co/Pt multilayer system irradiated at different temperatures. The as-deposited and irradiated samples have been characterized using x-ray reflectivity (XRR), x-ray diffraction (XRD) and the magneto-optical Kerr effect (MOKE). X-ray reflectivity shows clear intermixing at the interfaces. The x-ray diffraction pattern shows that Si+ ion irradiation at higher temperatures results in the formation of the CoPt3 fcc phase with a small fraction of L10 phase. The mixing process is discussed in terms of recoil displacements induced by energy transfers from ions.

Kavita, S.; Raghavendra Reddy, V.; Amirthapandian, S.; Gupta, Ajay; Panigrahi, B. K.

2009-03-01

127

Ion and neutral energy flux distributions to the cathode in glow discharges in Ar/Ne and Xe/Ne mixtures  

NASA Astrophysics Data System (ADS)

The work presented in the article is a study of the heavy particle (ion and neutral) energy flux distributions to the cathode in conditions typical of discharges used for luminous signs for advertising (``neon'' signs). The purpose of this work is to evaluate the effect of the gas mixture on the sputtering of the cathode. We have combined two models for this study: a hybrid model of the electrical properties of the cathode region of a glow discharge and a Monte Carlo simulation of the heavy particle trajectories. Using known sputtering yields for Ne, Ar, and Xe on iron cathodes, we estimate the sputtered atom flux for mixtures of Ar/Ne and Xe/Ne as a function of the percent neon in the mixture.

Capdeville, H.; Pédoussat, C.; Pitchford, L. C.

2002-02-01

128

Charging of dielectrics under focused ion beam irradiation  

SciTech Connect

We present a detailed experimental and theoretical study of the charging of silicon nitride and silicon oxide thin films following focused ion beam irradiation. The samples were irradiated using 30 keV Ga{sup +} ions at different ion doses and their consequent work function changes were measured by Kelvin probe force microcopy. The surface potential of both samples increased following the ion irradiation up to a critical ion dose, and then moderately decreased. The dependence of the sample surface potential on the irradiated ion dose is analyzed by taking into account all the main factors affecting charging in dielectric thin films: electron-hole generation by the incident fast ions, secondary ion-electron emission, sputtering of surface atoms, electron-hole recombination, electron recombination with the incident stopped ions, hole leakage current to the Si substrate, and various charge trapping processes. It was found that the much larger surface potential induced in Si{sub 3}N{sub 4} in comparison to SiO{sub 2} is associated with the different resistance to the Ga{sup +} ion bombardment. Under equal ion irradiation dose, a larger concentration of shallow traps is created in SiO{sub 2} than in Si{sub 3}N{sub 4}. This leads to an increased hole capture in shallow traps versus deep traps, and a consequent decrease in the surface potential.

Yogev, S.; Levin, J. [Applied Materials, Rehovot 76705 (Israel); Molotskii, M.; Schwarzman, A.; Avayu, O.; Rosenwaks, Y. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel-Aviv University, Ramat Aviv 69978 (Israel)

2008-03-15

129

Enhanced sputtering yields of carbon due to accumulation of low-energy Xe ions  

NASA Astrophysics Data System (ADS)

We have calculated the sputtering yields of carbon and molybdenum under xenon ion bombardment by a Monte Carlo code ACAT which simulates binary collision events in solids. The yields of carbon calculated with ACAT differ from the experimental data below the threshold energy predicted from the semi-empirical formula proposed by Yamamura and Tawara. Meanwhile, the results of ACAT with 14% xenon atoms retained in graphite are in good agreement with the experimental data and the xenon retention in carbon plays an important role in reducing the threshold energy for carbon sputtering. In order to estimate the experimental sputtering yields of carbon, a simplified formula is proposed in the frame of the semi-empirical formula. The formula predicts the yield curve close to the reported sputtering yields of carbon for the condition that carbon target retains 14% xenon atoms.

Kenmotsu, T.; Wada, M.; Hyakutake, T.; Muramoto, T.; Nishida, M.

2009-05-01

130

Online monitor of heavy ion flux in an ion irradiation apparatus for semiconductor irradiation test  

NASA Astrophysics Data System (ADS)

An online monitor of heavy ion flux for semiconductor irradiation test was developed and tested. The monitor consists of four annular-shaped segmented secondary electron emission monitors (S-SEMs) arranged in a quadrature around the central area of a beam line. Each SEM detects heavy ions diffused to the outer side from the center of the beam by a scatterer to expand the beam size without interference with the central part of the beam. Each SEM is independent, then the count of each SEM reflects the beam position or profile. Therefore, the device can be used as an online monitor for beam intensity and position. The device is named S-SEM. S-SEM was installed in an ion irradiation apparatus for semiconductor devices at the Tohoku University K=110 AVF cyclotron. We tested its performance and demonstrated that the S-SEM enables us to monitor the heavy ion flux down to lower than 104 #/cm2 s, without any energy loss to the beam. Further, S-SEM provides information on the beam position in both vertical and horizontal directions as expected.

Makino, Takahiro; Hagiwara, Masayuki; Itoga, Toshiro; Baba, Mamoru

2008-05-01

131

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)×10-10 cm3/s at 75 W rf power which slowly increases to (2.9+/-0.3)×10-10 cm3/s at 250 W (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

132

QUB Low Energy Ion-Ices Irradiation Experiment  

Microsoft Academic Search

Ion processing plays an important role in the chemical and physical modification of ice surfaces in astrophysical environments. This experimental project supported by the LASSIE ITN, led by Dr Tom Field, will investigate irradiation of astrophysical ice analogues by singly and multiply charged ion analogues of cosmic rays. Singly or multiply charged ions of either gaseous or solid elements are

A. Muntean; T. Field; A. Hunniford; B. McCullough; J. Konanoff; T. Millar

2011-01-01

133

Direct observation of ion-irradiation-induced chemical mixing  

SciTech Connect

Irradiation-induced dissolution of particles and mixing at heterogeneous interfaces in materials is of importance for ion beam processing and radiation materials sciences. Modeling has predicted dissolution of particles and homogenization at sharp chemical interfaces; imaging and depth profiling techniques have also been used to observe damage and mixing resulting from ion or neutron bombardment. Analytical scanning transmission electron microscopy has been used to directly observe the ion-irradiation induced elemental mixing and dissolution of {approx}25-50 nm titanium oxycarbonitrides in a nanostructured ferritic alloy irradiated at 173 K. The magnitude of the mixed zone is consistent with radiation damage theory.

Edmondson, Philip D [ORNL; Miller, Michael K [ORNL; Parish, Chad M [ORNL; Zhang, Yanwen [ORNL

2011-01-01

134

Direct Observation of Ion-irradiation-induced Chemical Mixing  

SciTech Connect

Irradiation-induced dissolution of particles and mixing at heterogeneous interfaces in materials is of importance for ion beam processing and radiation materials sciences. Modeling has predicted dissolution of particles and homogenization at sharp chemical interfaces; imaging and depth profiling techniques have also been used to observe damage and mixing resulting from ion or neutron bombardment. Analytical scanning transmission electron microscopy has been used to directly observe the ion-irradiation induced elemental mixing and dissolution of {approx}25-50 nm titanium oxycarbonitrides in a nanostructured ferritic alloy irradiated at 173 K. The magnitude of the mixed zone is consistent with radiation damage theory.

Parish, Chad M.; Edmondson, P. D.; Zhang, Yanwen; Miller, Michael K.

2011-11-01

135

Light-emitting Si nanostructures formed in SiO{sub 2} on irradiation with swift heavy ions  

SciTech Connect

SiO{sub 2} layers containing implanted excess Si are irradiated with Xe ions with an energy of 130 MeV and doses of 3 x 10{sup 12}-10{sup 14} cm{sup -2}. In the samples irradiated with a dose of 3 x 10{sup 12} cm{sup -2}, {approx}10{sup 12} cm{sup -2} segregated clusters 3-4 nm in dimension are detected by transmission electron microscopy. With increasing dose, the dimensions and number of these clusters increase. In the photoluminescence spectrum, a 660- to 680-nm band is observed, with the intensity dependent on the dose. After passivation of the sample with hydrogen at 500 deg. C, the band disappears, but a new {approx}780-nm band typical of Si nanocrystals becomes evident. On the basis of the entire set of data, it is concluded that the 660- to 680-nm band is associated with imperfect Si nanocrystals grown in the tracks of Xe ions due to high ionization losses. The nonmonotonic dependence of the photoluminescence intensity on the dose is attributed to the difference between the diameters of tracks and the diameters of the displacements' cascades responsible for defect formation.

Kachurin, G. A., E-mail: kachurin@isp.nsc.ru; Cherkova, S. G. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Skuratov, V. A. [Joint Institute for Nuclear Research (Russian Federation); Marin, D. V.; Cherkov, A. G. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2010-04-15

136

Dependence of secondary ion emission from organic material on the energy loss of the impacting heavy ion.  

National Technical Information Service (NTIS)

Samples of the amino acid valine were irradiated by 2.5 MeV-Ar, 0.8 MeV-Kr and 1.0 MeV Xe beams from the Argonne Dynamitron accelerator in order to study the energy distributions of ejected secondary ions. For Kr and Xe the nuclear stopping power exceeded...

J. E. Hunt K. Wien

1991-01-01

137

Quest for experimental M1 and E1-intercombination transition probabilities in few-electron Xe ions  

NASA Astrophysics Data System (ADS)

The experimental access to M1 transition probabilities within the ns 2 np k (1 ? k ? 5) ground state configurations of highly ionized atoms is outlined. A test experiment on Xe(45 50)+ yielded first spectra and decay curves of the 2 s 2 1 S 0 - 2 s2 p 3 P {1/0} intercombination transition in Xe50+ and of M1 transitions within the 2 s 2 2 p k (1 ? k ? 5) ground configurations. The data compare well only with theoretical predictions which take the Lamb shift into account. Problems and prospects for better measurements are discussed.

Möller, G.; Träbert, E.; Heckmann, P. H.; Mokler, P. H.; Livingston, A. E.

1991-09-01

138

Atomistic simulations of MeV ion irradiation of silica  

NASA Astrophysics Data System (ADS)

We used molecular dynamics simulations to study 2.3 MeV Au ion irradiation of silica. In this energy regime, the energy loss of the ion is divided almost equally between electronic and nuclear energy loss. The inelastic thermal spike model was used to model the electron-phonon interactions due to the high electronic energy loss. Binary collision approximation calculations provided input for the recoil energies due to MeV ions. We performed simulations of the damage due to the separate damage mechanisms as well as together, and found that the inelastic thermal spike is needed to accurately simulate the irradiation damage from MeV ions.

Backman, M.; Djurabekova, F.; Pakarinen, O. H.; Nordlund, K.; Zhang, Y.; Toulemonde, M.; Weber, W. J.

2013-05-01

139

Heavy-ion irradiation induced diamond formation in carbnaceous materials.  

National Technical Information Service (NTIS)

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...

T. Daulton

1999-01-01

140

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

141

SWIFT HEAVY ION IRRADIATION EFFECTS ON DOPED ALKALI HALIDES  

Microsoft Academic Search

The effects produced by heavy ion irradiation in KBr:Ag and KCl:Ag crystals are investigated using optical spectroscopy. For KCl, the results are compared with the effects obtained in the pure crystals. After irradiation with heavy ions up to 11.2 MeV\\/u specific energy, the absorption bands suffer a series of changes, related to the structure of defects and also to their

M. Enculescu

142

Interdiffusion in polystyrene crosslinked by keV ion irradiation  

Microsoft Academic Search

Mass transport properties of polymers are deeply influenced by the presence of crosslinks between chains, induced by high-energy ion irradiation. Diffusion coefficients in polystyrene, measured after irradiation with 300-keV protons in the fluence range 1012–1014 ions\\/cm2, show strong variation up to two orders of magnitude. Diffusion process has been studied in deuterated\\/hydrogenated polystyrene bilayer by using the forward recoil analysis

L. Calcagno; G. Foti

1992-01-01

143

Swift heavy ion irradiation of titanium phosphate and related materials  

Microsoft Academic Search

Amorphous and crystalline (both, ?- and ?-forms) titanium phosphate, titanium molybdate and tungstate were irradiated with swift heavy ions of 84Kr and 203Bi at a fluence of 5×1010–1014ioncm?2. The crystalline structure of the materials was characterized by XRD method before and after irradiation. Comparison of the powder diffraction patterns revealed that the irradiation had practically no effect on the materials

L. Szirtes; J. Megyeri; L. Riess; E. Kuzmann; K. Havancsák

2005-01-01

144

Measured and calculated SF{sub 6}{sup -} collision and swarm ion transport data in SF{sub 6}-Ar and SF{sub 6}-Xe mixtures  

SciTech Connect

The measurement of the mobility of SF{sub 6}{sup -} in the mixtures SF{sub 6}-Ar and SF{sub 6}-Xe is reported over the density-reduced electric field strength E/N 1-180 Td (1 Townsend=10{sup -17} V cm{sup 2}), from a time-resolved pulsed Townsend technique. Simultaneously, the mobility of SF{sub 6}{sup -} in the same binary mixtures has been calculated from a set of collision cross sections for SF{sub 6}{sup -}-Ar, SF{sub 6}{sup -}-Xe, and SF{sub 6}{sup -}-SF{sub 6} using a Monte Carlo simulation procedure for ion transport. The good agreement between measured and calculated mobilities in these gas mixtures has led us to conclude that the validation of our cross section sets is confirmed. The elastic collision cross section, a predominant process for ion energies lower than about 10 eV, was determined from a semiclassical JWKB approximation using a rigid core potential model for the ion-neutral systems under consideration. This elastic cross section was then added to several other inelastic collision cross sections found in the literature for ion conversion, electron detachment of SF{sub 6}{sup -} and charge transfer. Moreover, the calculations of the mobility and the ratios of the transverse and longitudinal diffusion coefficients to the mobility were extended into a much wider E/N range from 1 to 4000 Td. Additionally, we have also calculated the energy distribution functions and the reaction coefficients for ion conversion and electron detachment. Finally, we have shown that the range of validity for the calculation of the mobility in gas mixtures from Blanc's law is only valid for the low E/N region, where the interaction is dominated by elastic collisions and the ion distribution function remains essentially Maxwellian.

Benhenni, M.; Yousfi, M.; Merbahi, N.; Eichwald, O. [Universite Paul Sabatier, CPAT, UMR 5002 du CNRS, 118 route de Narbonne, 31062 Toulouse cedex (France); Urquijo, J. de; Hinojosa, G. [Centro de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Apartado Postal 48-3, 62251, Cuernavaca, Mor. (Mexico); Hernandez-Avila, J.L. [Universidad Autonoma Metropolitana, CBI-Energia, Av. San Pablo 180, 02200 Mexico, D.F. (Mexico)

2005-03-01

145

Study on effects of energetic ion irradiation in Gd2O3-doped CeO2 by means of synchrotron radiation X-ray spectroscopy  

NASA Astrophysics Data System (ADS)

To study the effects of Gd2O3-doping and the irradiation with high energy fission products in the nuclear fuels (UO2), Gd2O3-doped CeO2 pellets, which are simulation materials of UO2, were irradiated with 200 MeV Xe14+ ions. Effects of Gd2O3-doping and the ion irradiation were estimated by using Extended X-ray Absorption Fine Structure (EXAFS) measurement. The interatomic distances between each Ce and the first nearest O atoms, and Ce and the second nearest Ce atoms increase by the irradiation and the effect of the ion irradiation on the atomic distances is more pronounced for higher amounts of dopant. The Debye-Waller factors for Ce-O and Ce-Ce pairs increase with increasing the amount of Gd2O3 dopant. These results suggest that the lattice binding energy is weakened by Gd2O3-doping. The Debye-Waller factors increase also by the irradiation. The effect of ion irradiation on the Debye-Waller factors, however, becomes smaller for higher amounts of dopant.

Tahara, Y.; Shimizu, K.; Ishikawa, N.; Okamoto, Y.; Hori, F.; Matsui, T.; Iwase, A.

2012-04-01

146

Ion irradiation tolerance of graphene as studied by atomistic simulations  

SciTech Connect

As impermeable to gas molecules and at the same time transparent to high-energy ions, graphene has been suggested as a window material for separating a high-vacuum ion beam system from targets kept at ambient conditions. However, accumulation of irradiation-induced damage in the graphene membrane may give rise to its mechanical failure. Using atomistic simulations, we demonstrate that irradiated graphene even with a high vacancy concentration does not show signs of such instability, indicating a considerable robustness of graphene windows. We further show that upper and lower estimates for the irradiation damage in graphene can be set using a simple model.

Ahlgren, E. H.; Lehtinen, O. [Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki (Finland); Kotakoski, J. [Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki (Finland); Department of Physics, University of Vienna, Boltzmanngasse 5, 1190 Wien (Austria); Krasheninnikov, A. V. [Department of Physics, University of Helsinki, P.O. Box 43, 00014 Helsinki (Finland); Department of Applied Physics, Aalto University, P.O. Box 1100, 00076 Aalto (Finland)

2012-06-04

147

Direct observation of ion-irradiation-induced chemical mixing  

Microsoft Academic Search

Irradiation-induced dissolution of particles and mixing at heterogeneous interfaces in materials is of importance for ion beam processing and radiation materials sciences. Modeling has predicted dissolution of particles and homogenization at sharp chemical interfaces; imaging and depth profiling techniques have also been used to observe damage and mixing resulting from ion or neutron bombardment. Analytical scanning transmission electron microscopy has

C. M. Parish; P. D. Edmondson; Y. Zhang; Michael K. Miller

2011-01-01

148

Characteristic x rays from multiple-electron capture by slow highly charged Ta{sup q+} ions from He and Xe atoms  

SciTech Connect

Characteristic x rays, emitted by slow (velocity {nu}{approx}0.3 a.u.) highly charged Ta{sup q+} (q=41-49) ions after multiple capture from He or Xe atoms, were investigated in coincidence with recoil ions. The x-ray spectra are distinctly different for single and double capture as well as for different target ionization potentials (He and Xe). For the open M-shell configurations of the projectile (q>45) the spectra are dominated by cascade transitions. There is no evidence for direct radiative transitions from Rydberg states into the M shell, indicating dominant capture into angular momentum states that forbids such transitions. From such features we get, by comparison with spectra obtained from the calculation of the radiative cascades, the angular momentum values of the captured electron. A simple model, including autoionization, is used to relate double- and single-capture x-ray spectra and to explain their differences. The x-ray spectra with projectiles having no initial M vacancies (q<45) can have an important contribution from the internal dielectronic excitation (IDE) process. It is found that this channel is drastically reduced for double capture from He and closed for projectiles with q=41, as expected from our calculations of the core-excited states in Ta{sup (q-1)+}. The x-ray spectra and photon yields in these heavy systems are thus determined by a competition between the relaxation channels: radiative relaxation, IDE, and, for multiple capture, autoionization.

Madzunkov, S. [Department of Atomic Physics, Stockholm University, Alba Nova S-10691 Stockholm (Sweden); Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); Fry, D. [Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); Lindroth, E.; Schuch, R. [Department of Atomic Physics, Stockholm University, Alba Nova S-10691 Stockholm (Sweden)

2006-03-15

149

Edge-on ion irradiation of electron microscope specimens  

SciTech Connect

A special technique is described for in situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen. That is, instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction with respect to the irradiation. The results of amorphization of Si, irradiated in this orientation by 1 or 1.5 MeV Kr, are presented and briefly compared with the usual plan view observations. The limitations of the technique are discussed and several experiments which might profitably employ this technique are suggested.

Otero, M.P. (Argonne National Lab., IL (United States) Fundacao de Tecnologia Industrial (FTI), Lorena, SP (Brazil)); Allen, C.W. (Argonne National Lab., IL (United States))

1992-01-01

150

Edge-on ion irradiation of electron microscope specimens  

SciTech Connect

A special technique is described for in situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen. That is, instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction with respect to the irradiation. The results of amorphization of Si, irradiated in this orientation by 1 or 1.5 MeV Kr, are presented and briefly compared with the usual plan view observations. The limitations of the technique are discussed and several experiments which might profitably employ this technique are suggested.

Otero, M.P. [Argonne National Lab., IL (United States)]|[Fundacao de Tecnologia Industrial (FTI), Lorena, SP (Brazil); Allen, C.W. [Argonne National Lab., IL (United States)

1992-07-01

151

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

152

Texture modification of wurtzite piezoelectric films by ion beam irradiation  

Microsoft Academic Search

Texture modification of wurtzite films in ion beam assisted deposition was investigated. Unusual (112¯0) texture formation appeared in the ZnO and AlN films prepared by grazing ion beam sputtering. Such a (112¯0) texture formation was also observed even in the ZnO film deposited under argon ion beam irradiation. Mechanism of the formation probably relates to physical interaction between energetic particle

Takahiko Yanagitani; Masato Kiuchi

2011-01-01

153

Gel behavior of keV ion irradiated polystyrene  

Microsoft Academic Search

Among the chemical and physical modifications induced by ion bombardment of polymers, the solubility changes are very important because of technological application for lithography in microelectronic devices. Solubility changes due to the occurrence of crosslinkings have been followed on monodisperse and polydisperse polystyrene after ion irradiations (1011–1014 ions\\/cm2, keV energy). By using the Inokuty gel theory [M. Inokuti J. Appl.

L. Calcagno; G. Foti; A. Licciardello; O. Puglisi

1988-01-01

154

Radiative recombination and photoionization cross sections for heavy element impurities in plasmas: II. Ions of Si, Cl, Ar, Ti, Cr, Kr, and Xe  

SciTech Connect

Total cross sections for radiative recombination with an electron for 36 ions of Si, Cl, Ar, Ti, Cr, Kr, and Xe as well as subshell photoionization cross sections are presented. The electron kinetic energy is {<=}50 keV. The calculations were performed using the relativistic Dirac-Fock method and the results have been included in a database of radiative recombination and photoionization cross sections for the heavy element impurity ions occurring in plasmas. The data are required for modelling fusion and astrophysical plasmas. To obtain the total radiative recombination cross section, calculations have been carried out for ground and all excited electron states up to states with the principal quantum number n = 20. The subshell photoionization cross sections for all states with n {<=} 12 and orbital momenta l {<=} 6 have been fitted by an analytical expression with five fit parameters which are tabulated.

Trzhaskovskaya, M.B. [Petersburg Nuclear Physics Institute, Theoretical Physics Division, 188300 Gatchina (Russian Federation)], E-mail: Trzhask@MT5605.spb.edu; Nikulin, V.K. [Ioffe Physical Technical Institute, 194021 St. Petersburg, Politechnicheskaya 26 (Russian Federation); Clark, R.E.H. [Nuclear Data Section, International Atomic Energy Agency, Wagramer Str. 5, A-1400 Vienna (Austria)

2009-11-15

155

The influence of helium ion irradiation on amorphous hydrocarbon films  

NASA Astrophysics Data System (ADS)

Amorphous hydrocarbon films were irradiated with 60-140 keV He ions at the dose ranging from 1.0 × 1015 to 1.0 × 1017 ions/cm2. The films about 1.4 ?m thick were deposited on Si substrates and irradiated at room temperature. The surface and mechanical properties of as-deposited and He ion irradiated hydrocarbon films were analyzed by using atomic force microscopy (AFM), AFM-based nanoindentation and scratching tests. Their chemical compositions and structural properties were evaluated by FTIR and Raman measurements. Analysis showed that the He ion irradiation led to a decrease in their surface roughness and an increase in the nanohardness and scratching resistance. FTIR measurements indicated that the content of bonded H atoms in hydrocarbon samples was greatly decreased due to the He ion irradiation, and a dense and covalent three-dimensional network was formed in films. The Raman data confirmed the microstructural evolution of samples into a dense metastable structure containing a large fraction of sp2 C clusters.

Fan, Hongyu; Sun, Li; Yang, Deming; Niu, Jinhai; Guo, Liping; Yang, Qi; Bi, Zhenhua; Liu, Dongping

2013-04-01

156

Fast fluorescence decay of naphthalene induced by Ar ion irradiation  

NASA Astrophysics Data System (ADS)

A single photon counting system was constructed for a time resolved fluorescence measurement with pulsed heavy ions from the AVF cyclotron in Takasaki Ion Accelerators for Advanced Radiation Application (TIARA). Fluorescence spectra and decay of naphthalene in poly(vinyl butylal) (PVB) film were observed from the irradiation with Ar ions. Though fluorescence spectra were assigned to the first singlet excited stale of naphthalene, the decay with Ar ion irradiation were faster than that excited by UV light. This faster decay results from quenching by the transient species produced. The relative initial concentration of the excited state of naphthalene to that of the radicals increases with increasing energy deposited along the incident ion's trajectory.

Taguchi, M.; Aoki, Y.; Namba, H.; Watanabe, R.; Matsumoto, Y.; Hiratsuka, H.

1997-02-01

157

Evaporation of ion-irradiated disks  

Microsoft Academic Search

We calculate the evaporation of a cool accretion disk around a black hole due to the ion-bombardment by an ion supported accretion flow (here ISAF, or optically thin ADAF). As first suggested by Spruit & Deufel (2002), this evaporation takes place in two stages: ion bombardment of the cool disk (Shakura-Sunyaev disk: SSD) produces an intermediate-temperature layer on top of

C. P. Dullemond; H. C. Spruit

2005-01-01

158

Evaporation of ion-irradiated disks  

Microsoft Academic Search

We calculate the evaporation of a cool accretion disk around a black hole due\\u000ato the ion-bombardment by an ion supported accretion flow (here ISAF, or\\u000aoptically thin ADAF). As first suggested by Spruit & Deufel (2002), this\\u000aevaporation takes place in two stages: ion bombardment of the cool disk\\u000a(Shakura-Sunyaev disk: SSD) produces an intermediate-temperature layer on top\\u000aof

C. P. Dullemond; H. C. Spruit

2005-01-01

159

AFM surface investigation of polyethylene modified by ion bombardment  

NASA Astrophysics Data System (ADS)

Polyethylene (PE) was irradiated with 63keV Ar+ and 155keV Xe+ ions to fluences of 1x1013 to 3x1015cm-2 with ion energies being chosen in order to achieve approximately the same penetration depth for both species. The PE surface morphology was examined by means of atomic force microscopy (AFM), whereas the concentration of free radicals and conjugated double bonds, both created by the ion irradiation, were determined using electron paramagnetic resonance (EPR) and UV-VIS spectroscopy, respectively. As expected, the degradation of PE was higher after irradiation with heavier Xe+ ions but the changes in the PE surface morphology were more pronounced for Ar+ ions. This newly observed effect can be explained by stronger compaction of the PE surface layer in the case of the Xe+ irradiation, connected with a reduction of free volume available.

Švor?ík, V.; Arenholz, E.; Hnatowicz, V.; Rybka, V.; Öchsner, R.; Ryssel, H.

1998-07-01

160

Structural modification of polymer films by ion irradiation  

NASA Astrophysics Data System (ADS)

The atomic and electronic structure of polymer films undergoes deep modifications during high energy (keV-MeV) ion irradiation, from molecular solid to amorphous material. At low energy density (1022-1024 eV/cm3) typical effects include chain scissions, crosslinks, molecular emission and double bonds formation. In hydrocarbon polymer (polystyrene, polyethylene) the main effect of irradiation is the formation of new bonds as detected by molecular weight distribution, solubility and optical measurements. Moreover the concentration of trigonal carbon (sp2) in the polymer changes with ion fluence (1011-1014 ions/cm2) and stabilizes to a value of 20% independently on the initial chemical structure of the irradiated sample. Photoemission spectroscopy shows an evolution of valence band states from localized to extended states. At high energy density (1024-1026 eV/cm3) the irradiated polymer continues to evolve showing spectroscopic characteristics close to those of hydrogenated amorphous carbon. Trigonal carbon concentration changes with ion fluence (1014-1016 ions/cm2) reaching the steady state value of 60% and the hydrogen concentration decreases to 20%. Moreover the values of the optical gap (2.5-0.5 eV) suggest the presence of medium range order in the obtained hydrogenated amorphous carbon. These values are consistent with the formation of graphitic clusters, whose size goes from 5 Å to 20 Å by changing the ion fluence (or energy density).

Calcagno, L.; Compagnini, G.; Foti, G.

1992-03-01

161

Directional ion emission from thin films under femtosecond laser irradiation  

SciTech Connect

Thin films of nickel have been irradiated using femtosecond laser pulses in vacuum. Subsequent emission of plasma ions is diagnosed using an ion probe. Angular distributions of the emitted ions are presented for a range of target film thicknesses. Data are compared to the Anisimov model of plasma expansion [S. I. Anisimov, D. Bauerle, and B. S. Luk'yanchuk, Phys. Rev. B 48, 12076 (1993)]. The tendency of the ions to be ejected at small angles to the normal of the target surface is explained in terms of the initial conditions of the plume. Results are explained in terms of the initial shape and adiabatic index of the plasma.

Williams, Gareth O.; Favre, Sebastian; O'Connor, Gerard M. [NCLA, School of Physics, National University of Ireland, Galway, University Rd., Galway (Ireland)

2009-03-09

162

Structural modification of polymer films by ion irradiation  

Microsoft Academic Search

The atomic and electronic structure of polymer films undergoes deep modifications during high energy (keV-MeV) ion irradiation, from molecular solid to amorphous material. At low energy density (1022-1024 eV\\/cm3) typical effects include chain scissions, crosslinks, molecular emission and double bonds formation. In hydrocarbon polymer (polystyrene, polyethylene) the main effect of irradiation is the formation of new bonds as detected by

L. Calcagno; G. Compagnini; G. Foti

1992-01-01

163

Thermal conductivity of SiC after heavy ions irradiation  

Microsoft Academic Search

In this study, we performed irradiation experiments on ?-SiC samples, with heavy ions at room temperature (74MeV Kr, fluence of 5×1014 ionscm?2). This energy results in an irradiated layer of about 9.6?m for SiC. TEM and Raman analyses reveal a graded damaged material. In the electronic interactions domain SiC is weakly damaged whereas it becomes fully amorphous in the nuclear

J. Cabrero; F. Audubert; R. Pailler; A. Kusiak; J. L. Battaglia; P. Weisbecker

2010-01-01

164

Effect of heavy ion-beam irradiation on plant growth and mutation induction in Nicotiana tabacum  

Microsoft Academic Search

Ion-beam mutagenesis is a highly effective way to rapidly create new cultivars. To optimize conditions for heavy ion mutagenesis, we irradiated tobacco (Nicotiana tabacum L.) tissues at various developmental stages with heavy ion beams of various doses and examined the effects of irradiation by monitoring plant growth and mutation induction. The effects differed among irradiated tissues. Sensitivity to heavy ion-beam

Yusuke Kazama; Hiroyuki Saito; Mashu Miyagai; Hinako Takehisa; Hiroyuki Ichida; Yutaka Miyazawa; Kei-ichiro Mishiba; Takeshi Kanaya; Kenichi Suzuki; Chang-Hyu Bae; Kazumitsu Miyoshi; Masahiro Mii; Tomoko Abe

165

Response of Strontium Titanate to Ion and Electron Irradiation  

SciTech Connect

Response of strontium titanate (SrTiO3) to ion and electron irradiation is studied at room temperature. For an accurate energy to depth conversion and a better determination of ion-induced disorder profile from Rutherford backscattering spectrometry measurement, a detailed iterative procedure is described and applied to ion channeling spectra to determine the dechanneling yield and the disorder profiles for the Sr and Ti sublattices. The result shows a large underestimation in disorder depth, ~ 40% at the damage peak, which indicates a large overestimation of the electronic stopping power for 1.0 MeV Au ions in SrTiO3 predicted by the SRIM (Stopping and Range of Ions in Matter) code. Overestimation of heavy ion stopping power may lead to an overestimation of the critical dose for amorphization. The current study also demonstrates possible ionization effects in SrTiO3 under ion and electron irradiation. Pre-amorphized SrTiO3 exhibits strong ionization-induced epitaxial recovery at the amorphous/crystalline interface under electron irradiation.

Zhang, Yanwen; Lian, Jie; Zhu, Zihua; Bennett, Wendy D.; Saraf, Laxmikant V.; Rausch, Julie L.; Hendricks, Catherine A.; Ewing, R. C.; Weber, William J.

2009-04-20

166

One and Two-Electron Investigation of Electronic Structure for Ba(+)Xe and BaXe van der Waals Molecules in a Pseudopotential Approach.  

PubMed

The potential energy curves, vibrational energy levels, spectroscopic constants, and dipole moment curves for the ground and excited states of BaXe and its ion Ba(+)Xe molecules are calculated with an ab initio method using pseudopotential techniques and core polarization potentials. The molecules are treated as two (BaXe) or one (Ba(+)Xe) active electrons systems taking benefit of the zero pseudopotential approach for Xe. The vibrational levels and their energy spacing have been also determined for ?(+), ?, and ? states. The permanent and transition dipole moment curves are investigated for the (1,3)?(+) states of the BaXe neutral molecule and (2)?(+) states of the Ba(+)Xe ion. The analysis of these numerous results shows interesting behavior in potential energy curves imprinted by the strong repulsive interactions between electron and Xe and also indicates an intense transition dipole moment for both Ba(+)Xe and BaXe. PMID:23987477

Abdessalem, Kawther; Mejrissi, Leila; Issaoui, Noureddine; Oujia, Brahim; Gadéa, Florent Xavier

2013-08-29

167

Atomic data for neutron-capture elements. III. Charge transfer rate coefficients for low-charge ions of Ge, Se, Br, Kr, Rb, and Xe  

NASA Astrophysics Data System (ADS)

We present total and final-state resolved charge transfer (CT) rate coefficients for low-charge Ge, Se, Br, Kr, Rb, and Xe ions reacting with neutral hydrogen over the temperature range 102-106 K. Each of these elements has been detected in ionized astrophysical nebulae, particularly planetary nebulae. CT rate coefficients are a key ingredient for the ionization equilibrium solutions needed to determine total elemental abundances from those of the observed ions. A multi-channel Landau Zener approach was used to compute rate coefficients for projectile ions with charges q = 2-5, and for singly-charged ions the Demkov approximation was utilized. Our results for five-times ionized species are lower limits, due to the incompleteness of level energies in the NIST database. In addition, we computed rate coefficients for charge transfer ionization reactions between the neutral species of the above six elements and ionized hydrogen. The resulting total and state-resolved CT rate coefficients are tabulated and available at the CDS. In tandem with our concurrent investigations of other important atomic processes in photoionized nebulae, this work will enable robust investigations of neutron-capture element abundances and nucleosynthesis via nebular spectroscopy. Tables 4 and 5 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A117

Sterling, N. C.; Stancil, P. C.

2011-11-01

168

Isotopic composition of Xe in the most acid-resistant fractions of the Efremovka CV3 chondrite  

NASA Astrophysics Data System (ADS)

Isotopic compositions of three samples (E19, E20, and E22) of the Efremovka carbonaceous chondrite, obtained after 'hard' acid treatment of the original specimens were investigated. Results indicate that the fine-grained E19 contains Xe enriched by nucleogenic Xe-X. Samples E20 and E22 were found to be enriched by Xe-136, Xe-134, Xe-128, Xe-126, and Xe-124, in ratios that have no analogies among acid-resistant residues of other carbonaceous chondrites. It is suggested that the enrichment of Efremovka samples by heavy Xe isotopes was caused by the presence of Xe = H (CCF = Xe) or a mixture of extensively mass-fractionated solar Xe with Xe = X, whereas the enrichment by light Xe isotopes was caused by a intense neutron irradiation of some of the mineral phases of these samples previous to accretion.

Fisenko, A. V.; Semenova, L. F.; Lavrukhina, A. K.; Shukoliukov, Iu. A.

1991-06-01

169

Elongated Co nanoparticles induced by swift heavy ion irradiations  

Microsoft Academic Search

Spherical nanoparticles have been formed in SiO2 layers by 160 keV Co+ ion implantation. Different particle sizes have been obtained depending on implantation fluence (2×1016, 5×1016 and 1×1017 Co+cm?2) and substrate temperature (77, 295 and 873 K). These spherical particles have been subsequently irradiated with 200 MeV 127I ions at fluences from 1011 to 1014 cm?2 at 300 K. Modifications

C. D’Orléans; J. P. Stoquert; C. Estournès; J. J. Grob; D. Muller; J. L. Guille; M. Richard-Plouet; C. Cerruti; F. Haas

2004-01-01

170

Superconductivity and structural disorder in ion-irradiated rhenium films  

SciTech Connect

Single- and polycrystalline Re films were irradiated at room temperature and liquid nitrogen temperature and 350-keV N ions and 700-keV doubly charged Ar ions. With increasing ion fluence phi, the ion-induced residual resistivity ..delta..rho/sub 0/ and the superconducting transition temperature T/sub c/ where observed to increase. The functional behavior of ..delta..rho/sub 0/(phi) and the recovery spectra are found to depend on ion species and phi. Annealing stages II and III are seen after low-dose N- and Ne-ion irradiation, whereas at high ion fluences stages II, IV, and V are most pronounced. Thus the increase of rho/sub 0/ at low fluences is attributed to vacancies mainly, and at high fluences to the formation of extended defects. The T/sub c/ increases at low fluences is caused by inhomogeneously distributed vacancies, and at high fluences by vacancies pinned to dislocations. Extended defects alone do not seem to have any influence on T/sub c/. Ion-induced recrystallization processes have also been observed.

ul Haq, A.; Meyer, O.

1982-10-01

171

Polymer film degradation under ion irradiation studied by ion beam induced luminescence (IBIL) and optical analyses  

NASA Astrophysics Data System (ADS)

In this work the real time evolution of luminescence properties of ion-irradiated polymer thin films was studied by means of ion beam induced luminescence (IBIL) measurements. The plastic scintillator NE102, a fluorinated polyimide and PMMA were irradiated by H+ (1.85 MeV), He+ (2.2 MeV) and N+ (1.2 MeV). The optical properties after irradiation were analysed with UV-Visible absorption, fluorescence spectroscopy and Fourier transform infrared spectroscopy (FT-IR), in order to correlate the IBIL measurements to the evolution of the optical and chemical properties of the matrix.

Quaranta, A.; Vomiero, A.; Carturan, S.; Maggioni, G.; Della Mea, G.

2002-05-01

172

Slowing down of fast electrons as probe for charging and decharging dynamics of ion-irradiated insulators  

SciTech Connect

The slowing down of fast electrons emitted from insulators [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Kr, Ag, Xe; 20-64 MeV/u) was measured by the time-of-flight method at LNS, Catania and GANIL, Caen. The charge buildup, deduced from both convoy- and binary-encounter electron peak shifts, leads to target material-dependent potentials (6.0 kV for Mylar, 2.8 kV for PP). The number of projectiles needed for charging up (charging-up time constant) is inversely proportional to the electronic energy loss. After a certain time, a sudden decharging occurs. For low beam currents, charging-up time, energy shift corresponding to maximum charge buildup, and time of decharging are regular. For high beam currents, the time intervals become irregular (chaotic).

De Filippo, E.; Lanzano, G. [Istituto Nazionale di Fisica Nucleare Sezione di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Amorini, F. [Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud, LNS, Via S. Sofia 62, I-95123 Catania (Italy); Geraci, E.; Grassi, L.; Politi, G. [Istituto Nazionale di Fisica Nucleare Sezione di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Via S. Sofia 64, I-95123 Catania (Italy); La Guidara, E. [Istituto Nazionale di Fisica Nucleare Sezione di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Centro Siciliano Fisica Nucleare e Struttura della Materia, CSFNSM, Catania (Italy); Lombardo, I. [Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud, LNS, Via S. Sofia 62, I-95123 Catania (Italy); Facolta di Ingegneria ed Architettura, Universita degli Studi di Enna 'Kore', Enna (Italy); Rizzo, F. [Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud, LNS, Via S. Sofia 62, I-95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Via S. Sofia 64, I-95123 Catania (Italy); Russotto, P. [Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud, LNS, Via S. Sofia 62, I-95123 Catania (Italy); Centro Siciliano Fisica Nucleare e Struttura della Materia, CSFNSM, Catania (Italy); Volant, C. [Departement Astrophysique, Physique des Particules, Physique Nucleaire et de l'Instrumentation Associee/Service de Physique Nucleaire, CEA/Saclay, F-91191 Gif-sur-Yvette (France); Hagmann, S. [GSI Helmholtzzentrum fuer Schwerionenforschung, D-64291 Darmstadt (Germany); Institut fuer Kernphysik IKF, J. W. Goethe Universitaet, Frankfurt am Main (Germany); Rothard, H. [Centre de Recherche sur les ions, les Materiaux et la Photonique, CIMAP-CIRIL-Ganil (CEA/CNRS/ENSICAEN/Universite de Caen-Basse Normandie), BP 5133, F-14070 Caen Cedex 05 (France)

2011-06-15

173

Ion beam irradiation in La2Zr2O7-Ce2Zr2O7 pyrochlore  

NASA Astrophysics Data System (ADS)

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 the critical amorphization temperature is low (~310 K). In this study we present data on ion beam irradiations of compositions in the solid solution: (La1-xCex)2Zr2O7 (x=0, 0.1, 0.2, 1). Ce is used as an analogue element for Pu because of similarities in charge and size. La2Zr2O7 can be amorphized by a 1.0 MeV Kr+ ion irradiation at 25 and 293 K at doses of ~1.19 and ~3.42 dpa, respectively, confirming that La2Zr2O7 is susceptible to ion irradiation-induced amorphization. With the addition of 10 mol% Ce in lanthanum-zirconate pyrochlore structure, no ion irradiation-induced amorphization has been observed at room temperature. The critical amorphization dose for (La0.9Ce0.1)2Zr2O7 at 25 K is ~3.55 dpa, and with increasing Ce-content, a higher dose (~5.20 dpa) is required to fully amorphize (La0.8Ce0.2)2Zr2O7 at 25 K. No amorphization occurred for Ce2Zr2O7 at 25 K at a dose of ~7 dpa. These results suggest that the addition of Ce into the La2Zr2O7 structure increases the stability of the La2Zr2O7 waste form in a radiation environment, which may be attributed to the decreasing average radius of cations in the A-site, resulting from the smaller ionic radii of Ce3+ (0.114 nm) and Ce4+ (0.097 nm) as compared to La3+ (0.116 nm). An ion beam-induced anion-disordered pyrochlore was observed prior to the final transformation to a disordered fluorite structure. The local structural evolution upon ion irradiation was also investigated for Ce-doped La2Zr2O7 pyrochlores with different average A-site cation sizes and valence states using electron energy-loss spectrometry (EELS).

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

2004-06-01

174

Intensive irradiation of carbon nanotubes by Si ion beam  

Microsoft Academic Search

Multi-walled carbon nanotubes were irradiated with 40 keV Si ion beam to a dose of 1 × 1017 cm?2. The multiple-way carbon nanowire junctions and the Si doping in carbon nanowires were realized. Moreover, the formation processes of carbon nanowire junctions and the corresponding mechanism were studied.

Zhichun NI; Qintao LI; Long YAN; Jinlong GONG; Dezhang ZHU; Zhiyuan ZHU

2007-01-01

175

Structure defects in germanium irradiated by helium and hydrogen ions  

SciTech Connect

Electron microscopy is used to study the structure of germanium layers irradiated by helium and hydrogen ions in a wide range of ion energies and subsequent annealing temperatures. It is shown that the main type of defect in germanium layers irradiated by helium ions is a cluster of interstitial atoms in the form of rod-shaped defects and )113) defects. Annealing these layers leads to a contraction of the dimensions of these defects and to their transformation into dislocation loops. The results of a study of the structural changes and of the electrophysical properties of the irradiated layers leads to the conclusion that the contraction of the dimensions of the rod-shaped defects and )113) defects takes place as a result of generation of interstitial atoms in the bulk of the crystal. The differences in the structure of layers irradiated by helium and hydrogen ions are due to different interaction mechanisms of the atoms of the implanted impurity with the radiation point defects.

Aseev, A.L.; Ivakhnishin, V.M.; Stas', V.F.; Smirnov, L.S.

1983-10-01

176

Tumor induction in mice after local irradiation with carbon ions  

NASA Astrophysics Data System (ADS)

The purpose of present study is to analyze retrospectively the tumor induction in mice that were irradiated with carbon ions originally for scoring early skin reaction. Male and female C3H mice at 12-16 weeks old were irradiated locally to their legs with 290 MeV/u carbon ions of modulated (6-cm Spread-Out-Bragg-Peak) beams. Dose-averaged LET (linear energy transfer) used here ranged from 14 and 135 keV/?m.Of 2096 mice irradiated, 1861 mice were used for analysis.Number of fractionated irradiation ranged 1 through 8.The interval time between each irradiation was 24 hr with some exception of less than 1 hour.The total doses ranged 7.6 Gy through 66.0 Gy.For Cs-137 gamma rays, number of fractionations ranged from 1 and 16 and the total doses ranged from 40 and 111 Gy. Irradiated legs were checked for possible tumor induction once a month after irradiation for up to 471 days, and were recorded positive when macroscopically judged as developing tumors.No more than one tumor was scored for one mouse. Tumors appeared at unirradiated site were excluded from analysis.Tumor induction was observed as early as 140 days after irradiation, and most frequent at Day 300 or later.No difference between carbon ions and gamma rays was observed for the time of tumor induction.When mice alive at the initial observation, i.e., 30 days after irradiation, number of these mice were counted and used for further analysis to calculate the tumor-induction frequency.Histological diagnosis obtained for 112 tumors indicated that malignant fibrous histiocytoma was the most common malignancy followed by fibrosarcoma.The frequency of tumor induction for carbon ions was 18 % (251/1387) while that of gamma rays was 16 % (77/474).Among carbon-ion groups, a high incidence (18%-20%) was observed for those including14, 20, 50 and 60keV/?m whereas a low incidence (16%) was observed for those including 40, 80 and 100 keV/?m.The frequency of tumor induced by 2, 3 or 4 fractionations (19%-20%) was higher than that by 1 or 8 fractionations (10%-16%) for gamma rays.A rough figure of relative biological effectiveness (RBE) was obtained by plotting the frequency of tumor induction against median dose that was calculated by combining all data together without any adjustment.The resultant RBE was 2.8 for an isoeffect of 17% tumor induction, and similar to the RBE for early skin reaction.

Koike, S.; Ando, K.; Oohira, C.; Ogiu, T.

177

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

178

Stability of uranium silicides during high energy ion irradiation  

SciTech Connect

Changes induced by 1.5 MeV Kr ion irradiation of both U{sub 3}Si and U{sub 3}Si{sub 2} have been followed by in situ transmission electron microscopy. When irradiated at sufficiently low temperatures, both alloys transform from the crystalline to the amorphous state. When irradiated at temperatures above the temperature limit for ion beam amorphization, both compounds disorder with the Martensite twin structure in U{sub 3}Si disappearing from view in TEM. Prolonged irradiation of the disordered crystalline phases results in nucleation of small crystallites within the initially large crystal grains. The new crystallites increase in number during continued irradiation until a fine grain structure is formed. Electron diffraction yields a powder-like diffraction pattern that indicates a random alignment of the small crystallites. During a second irradiation at lower temperatures, the small crystallizes retard amorphization. After 2 dpa at high temperatures, the amorphization dose is increased by over twenty times compared to that of initially unirradiated material.

Birtcher, R.C; Wang, L.M.

1991-11-01

179

Ion irradiation damage on tin side surface of float glass  

NASA Astrophysics Data System (ADS)

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 100 keV 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 tin side increases from 8 Å to 41 Å. Surface density also modified significantly with a redistribution of surface impurities. Monte Carlo simulations suggest that the displacement of tin and Fe impurities are responsible for the surface damage, which are experimentally examined by employing the total reflection X-ray fluorescence technique. Morphological and density changes are analyzed by grazing incidence X-ray reflectivity and atomic force microscopy techniques. Subsequent changes in surface morphology of float glass by ion irradiation are explained.

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

2005-10-01

180

Computational materials science of ion irradiation  

Microsoft Academic Search

The computational description of ion beam effects in solids began with binary collision models, which have proven to be very successful in describing a wide range of ballistic aspects of radiation-induced phenomena. But these models cannot describe well radiation-induced phenomena influenced by thermodynamics, such as heat spikes, phase changes, and the production of complex defects. Molecular dynamics (MD) methods are

K. Nordlund

2002-01-01

181

Effects of Ga ion-beam irradiation on monolayer graphene  

NASA Astrophysics Data System (ADS)

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; Ge, Daohan; Zhang, Yanmin; Shao, Ying; Ren, Naifei

2013-08-01

182

Comparison of irradiation hardening and microstructure evolution in ion-irradiated delta and epsilon hydrides  

NASA Astrophysics Data System (ADS)

A ?-Zr-hydride was irradiated with 6.4 MeV Fe3+ ions to clarify the relationship between hardening and microstructural changes of bulk Zr-hydrides under neutron irradiation. Irradiation hardening was measured by nanoindentation tests. Transmission electron microscope cross-sectional observations showed that the deformation mechanism of the ?-Zr-hydride was both slip and twinning. Dislocation loops were observed in the irradiated hydride matrix. These irradiation-induced defects make slip deformation difficult and consequently promote the twin deformation of ?-Zr-hydride. This work is a continuation of the previous our work (J. Nucl. Mater. 419 (2011) 366-370) focused upon ?-Zr-hydride and we discuss a comparison between the two Zr-hydrides.

Oono, Naoko; Kasada, Ryuta; Higuchi, Toru; Sakamoto, Kan; Nakatsuka, Masafumi; Hasegawa, Akiko; Kondo, Sosuke; Iwata, Noriyuki Y.; Matsui, Hideki; Kimura, Akihiko

2013-11-01

183

Ion irradiation effects on the exchange bias in IrMn/Co films  

SciTech Connect

The present work reports on the influence of ion irradiation in exchange-coupled bilayers. Magnetron-sputtered IrMn{sub 4}/Co films were irradiated with 40 keV He{sup +} ions and the dependence of their magnetic properties was studied as function of ion fluence and current used during the irradiations. The effects of ion damage and electronic excitation were also studied through additional irradiations with H{sup +} and Ne{sup +} ions. The results show a clear dependence of the exchange-bias field on the defects caused by the ion bombardment. No correlations with other irradiation effects were observed.

Schafer, D.; Grande, P. L.; Pereira, L. G.; Geshev, J. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, 91501-970 Rio Grande do Sul (Brazil)

2011-01-15

184

Effects on focused ion beam irradiation on MOS transistors  

SciTech Connect

The effects of irradiation from a focused ion beam (FIB) system on MOS transistors are reported systematically for the first time. Three MOS transistor technologies, with 0.5, 1, and 3 {mu}m minimum feature sizes and with gate oxide thicknesses ranging from 11 to 50 nm, were analyzed. Significant shifts in transistor parameters (such as threshold voltage, transconductance, and mobility) were observed following irradiation with a 30 keV Ga{sup +} focused ion beam with ion doses varying by over 5 orders of magnitude. The apparent damage mechanism (which involved the creation of interface traps, oxide trapped charge, or both) and extent of damage were different for each of the three technologies investigated.

Campbell, A.N.; Peterson, K.A.; Fleetwood, D.M.; Soden, J.M.

1997-04-01

185

Swift heavy ion irradiation of polystyrene  

Microsoft Academic Search

We have studied by Fourier transform infrared spectroscopy the chemical modifications induced by swift heavy ions in polystyrene. The overall destruction yield becomes very significant at high electronic stopping power (dEdx)e and the radiation sensitivity of this aromatic polymer merges typical values of equivalent aliphatic polymers as polyethylene. So, the radiation resistance conferred, at low (dEdx)e, to polystyrene by the

E. Balanzat; S. Bouffard; A. Bousquerel; J. Devy; Chr. Gaté

1996-01-01

186

Properties of ion track in polystyrene irradiated with high energy 56Fe ions  

NASA Astrophysics Data System (ADS)

Polystyrene (PS) films were irradiated with 1.157 GeV 56Fe ions at room temperature to fluences of 1 × 1012 ions/cm2 at various electronic energy loss values. Ultraviolet-visible (UV-vis) spectra were measured to investigate the optical properties of the irradiated materials. Optical constants of virgin and irradiated PS were evaluated in the UV-vis frequence range through fitting of UV-vis spectra with the multi-Lorentz model. Furthermore, effective medium theory was applied to evaluate the optical constants of materials in the ion track area. It is found that the refractive index of ion track material decreased significantly in the ultraviolet-visible range whereas its extinction coefficient increased. Gas atom release and carbon atom conglomerating are believed to be the reason. The extracted track radius and its variation with electronic energy loss values are in good agreement with earlier studies.

Ma, Mingwang; Wu, Shengwei; Lin, Jun; Sun, Youmei; Jin, Yunfan; Zhu, Zhiyong

2012-09-01

187

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

188

Blue shift of photoluminescence spectrum of porous silicon by helium ion irradiation  

Microsoft Academic Search

Effects of helium ion irradiation on photoluminescence spectrum of porous silicon were investigated. Photoluminescence spectra were measured for silicon prepared by only anodization (porous silicon), by only helium ion irradiation, and by helium ion irradiation before or after anodization. The porous silicon prepared only by anodization showed a photoluminescence spectrum with a peak intensity at 650nm. The silicon prepared only

Y Yamauchi; T Sakurai; Y Hirohata; T Hino; M Nishikawa

2002-01-01

189

The mechanism and kinetics of energy transfer processes in Xe-CCl4-M (M=CO, CO2) mixtures irradiated by xenon resonance light  

NASA Astrophysics Data System (ADS)

The mechanism and kinetics of energy transfer from the Xe(6s[3/2]1) resonance state to CO and CO2 molecules have been investigated by XeCl(B-X) (?max=308 nm) fluorescence intensity measurements at stationary conditions in Xe-CCl4-M systems. Steady-state analysis of the fluorescence intensity dependence on the xenon and M pressure at constant CCl4 concentration shows that these processes occur in two- and three-body reactions: Xe(6s[3/2]10)+M-->products Xe(6s[3/2]10)+M+Xe-->products. The two-body rate constants for above reactions have been found to be (0.7+/-0.2)x10-10 and (4.9+/-0.4)x10-10 cm3 s-1 for CO and CO2, respectively. The three-body rate constants have been found to be (3+/-1)x10-29 and (2.4+/-0.3)x10-28 cm6 s-1 for CO and CO2, respectively. It has been shown that the third order reaction is a very effective channel of xenon excited atoms decay at high xenon pressures (P50 Torr).

Wojciechowski, K.

1999-01-01

190

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

191

Kr Ion Irradiation Study of the Depleted-Uranium Alloys  

SciTech Connect

Fuel development for the Reduced Enrichment Research and Test Reactor program is tasked with the development of new low-enriched uranium nuclear fuels that can be employed to replace existing highly enriched uranium fuels currently used in some research reactors throughout the world. For dispersion-type fuels, radiation stability of the fuel/cladding interaction product has a strong impact on fuel performance. Three depleted uranium alloys are cast for the radiation stability studies of the fuel/cladding interaction product using Kr ion irradiation to investigate radiation damage from fission products. SEM analysis indicates the presence of the phases of interest: U(Si, Al)3, (U, Mo)(Si, Al)3, UMo2Al20, U6Mo4Al43, and UAl4. Irradiations of TEM disc samples were conducted with 500 keV Kr ions at 200ºC to ion doses up to 2.5 × 1015 ions/cm2 (~ 10 dpa) with an Kr ion flux of 1012 ions/cm2-sec (~ 4.0 × 10-3 dpa/sec). Microstructural evolution of the phases relevant to fuel-cladding interaction products was investigated using transmission electron microscopy.

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

2010-12-01

192

Swift heavy ions irradiation studies on some ferrite nanoparticles  

Microsoft Academic Search

Ferrite nanoparticles of two different systems, namely Ni0.65Zn0.375In0.25Ti0.025Fe1.70O4 and Mn0.75Zn0.18Fe2.07O4, have been prepared by two different methods of ball milling (mechano synthesis) and coprecipitation (soft chemistry) respectively to investigate the effect of swift heavy ion irradiations on the structural, magnetic and ferromagnetic resonance parameters on these systems. The powder samples of Ni–Zn and Mn–Zn ferrites were irradiated with 190MeV Ag15+

B. Parvatheeswara Rao; K. H. Rao; P. S. V. Subba Rao; A. Mahesh Kumar; Y. L. N. Murthy; K. Asokan; V. V. Siva Kumar; Ravi Kumar; N. S. Gajbhiye; O. F. Caltun

2006-01-01

193

Ion Beam Irradiation Studies Of Ultrananocrystalline Diamond (UNCD)  

NASA Astrophysics Data System (ADS)

Investigations into the effects of high-energy ion bombardment of ultrananocrystalline diamond (UNCD) thin films was performed using 3 and 6 MeV protons and 24 MeV F4+, with the fluence of 2.1×1017 ions/cm2, 2.9×1017 ions/cm2, and 6.7×1015 ions/cm2 respectively. Objective of the research is to investigate the effect of structural damage on the physical properties of the material and compare it with the structure of unirradiated and N doped UNCD. Pre- and post-irradiated samples were analyzed by ion beam analysis (IBA) measurements, Raman spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). IBA measurements including Rutherford backscattering spectrometry (RBS), non-Rutherford backscattering spectrometry (NRBS) and elastic recoil detection analysis (ERDA) were used to determine elemental concentration of pre- and post-irradiated samples. Visible Raman spectra corresponding to samples irradiated at 3 and 6 MeV protons did not show much variation. For 24 MeV F4+ irradiated sample, significant changes were observed, particularly the loss of a shoulder at 1179 cm-1 and sharpening of the G peak at around 1532 cm-1, indicating possible significant changes at the grain boundary and increase in sp2 phase. AFM measurements show a reduction in RMS roughness after bombardment possibly due to the graphitization of the UNCD surface. The results of IBA measurements did not show any change in the elemental concentration or interface region between film and substrate.

Kayani, A.; Garratt, E.; Alfaify, S.; Dissanayake, A.; Tecos, G.; Mancini, D. C.; Syed, M.

2011-06-01

194

Shallow BF2 implants in Xe-bombardment-preamorphized Si: The interaction between Xe and F  

NASA Astrophysics Data System (ADS)

Si(100) samples, preamorphized to a depth of ~30 nm using 20 keV Xe ions to a nominal fluence of 2×1014 cm-2 were implanted with 1 and 3 keV BF2 ions to fluences of 7×1014 cm-2. Following annealing over a range of temperatures (from 600 to 1130 °C) and times the implant redistribution was investigated using medium-energy ion scattering (MEIS), secondary ion mass spectrometry (SIMS), and energy filtered transmission electron microscopy (EFTEM). MEIS studies showed that for all annealing conditions leading to solid phase epitaxial regrowth, approximately half of the Xe had accumulated at depths of 7 nm for the 1 keV and at 13 nm for the 3 keV BF2 implant. These depths correspond to the end of range of the B and F within the amorphous Si. SIMS showed that in the preamorphized samples, approximately 10% of the F migrates into the bulk and is trapped at the same depths in a ~1:1 ratio to Xe. These observations indicate an interaction between the Xe and F implants and a damage structure that becomes a trapping site. A small fraction of the implanted B is also trapped at this depth. EXTEM micrographs suggest the development of Xe agglomerates at the depths determined by MEIS. The effect is interpreted in terms of the formation of a volume defect structure within the amorphized Si, leading to F stabilized Xe agglomerates or XeF precipitates.

Werner, M.; van den Berg, J. A.; Armour, D. G.; Carter, G.; Feudel, T.; Herden, M.; Bersani, M.; Giubertoni, D.; Ottaviano, L.; Bongiorno, C.; Mannino, G.; Bailey, P.; Noakes, T. C. Q.

2005-04-01

195

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

196

Discharging dynamics of insulator surfaces irradiated by highly charged ions  

NASA Astrophysics Data System (ADS)

Guiding and focusing of keV to MeV ions by insulator micro-capillaries offer exciting perspectives for the production of low divergence micro-sized beams and the spatial control over the irradiated zone. These effects result from the local charging of the capillary inner wall and depend strongly on the charging/discharging dynamics of the insulating material. This dynamics has been studied on various glass insulator surfaces (borosilicate, fused silica and quartz) by grazing incidence highly charged ion beams. We propose simple experimental methods to derive the relevant time constant and study the influence of temperature and different material properties to the charging process.

Bundaleski, N.; Khemliche, H.; Rousseau, P.; Cassimi, A.; Maunoury, L.; Roncin, P.

2009-04-01

197

Tunable nanometer electrode gaps by MeV ion irradiation  

PubMed Central

We report the use of MeV ion-irradiation-induced plastic deformation of amorphous materials to fabricate electrodes with nanometer-sized gaps. Plastic deformation of the amorphous metal Pd80Si20 is induced by 4.64 MeV O2+ ion irradiation, allowing the complete closing of a sub-micrometer gap. We measure the evolving gap size in situ by monitoring the field emission current-voltage (I-V) characteristics between electrodes. The I-V behavior is consistent with Fowler-Nordheim tunneling. We show that using feedback control on this signal permits gap size fabrication with atomic-scale precision. We expect this approach to nanogap fabrication will enable the practical realization of single molecule controlled devices and sensors.

Cheang-Wong, J.-C.; Narumi, K.; Schurmann, G. M.; Aziz, M. J.; Golovchenko, J. A.

2012-01-01

198

Tunable nanometer electrode gaps by MeV ion irradiation  

SciTech Connect

We report the use of MeV ion-irradiation-induced plastic deformation of amorphous materials to fabricate electrodes with nanometer-sized gaps. Plastic deformation of the amorphous metal Pd{sub 80}Si{sub 20} is induced by 4.64 MeV O{sup 2+} ion irradiation, allowing the complete closing of a sub-micrometer gap. We measure the evolving gap size in situ by monitoring the field emission current-voltage (I-V) characteristics between electrodes. The I-V behavior is consistent with Fowler-Nordheim tunneling. We show that using feedback control on this signal permits gap size fabrication with atomic-scale precision. We expect this approach to nanogap fabrication will enable the practical realization of single molecule controlled devices and sensors.

Cheang-Wong, J.-C.; Narumi, K.; Schuermann, G. M. [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Aziz, M. J. [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Golovchenko, J. A. [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States)

2012-04-09

199

Detecting swift heavy ion irradiation effects with graphene  

NASA Astrophysics Data System (ADS)

In this paper we show how single layer graphene can be utilized to study swift heavy ion (SHI) modifications on various substrates. The samples were prepared by mechanical exfoliation of bulk graphite onto SrTiO3, NaCl and Si(1 1 1), respectively. SHI irradiations were performed under glancing angles of incidence and the samples were analysed by means of atomic force microscopy in ambient conditions. We show that graphene can be used to check whether the irradiation was successful or not, to determine the nominal ion fluence and to locally mark SHI impacts. In case of samples prepared in situ, graphene is shown to be able to catch material which would otherwise escape from the surface.

Ochedowski, O.; Akcöltekin, S.; Ban-d‘Etat, B.; Lebius, H.; Schleberger, M.

2013-11-01

200

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

201

Tunable nanometer electrode gaps by MeV ion irradiation.  

PubMed

We report the use of MeV ion-irradiation-induced plastic deformation of amorphous materials to fabricate electrodes with nanometer-sized gaps. Plastic deformation of the amorphous metal Pd(80)Si(20) is induced by 4.64 MeV O(2+) ion irradiation, allowing the complete closing of a sub-micrometer gap. We measure the evolving gap size in situ by monitoring the field emission current-voltage (I-V) characteristics between electrodes. The I-V behavior is consistent with Fowler-Nordheim tunneling. We show that using feedback control on this signal permits gap size fabrication with atomic-scale precision. We expect this approach to nanogap fabrication will enable the practical realization of single molecule controlled devices and sensors. PMID:22550357

Cheang-Wong, J-C; Narumi, K; Schürmann, G M; Aziz, M J; Golovchenko, J A

2012-04-11

202

Disordering and dissolution of ?' precipitates under ion irradiation  

NASA Astrophysics Data System (ADS)

The stability of the ?' phase of the nickel-base alloy Nimonic PE16 under irradiation with Ni+ ions of 300-keV energy is studied by means of transmission electron microscopy. The disordering of the ?' phase could be followed as a function of fluence. The main finding is the observation of weak but measurable superlattice reflections between 0.1 and 1 dpa after irradiation at room temperature. The superlattice reflections disappear in two steps. Their intensities decrease considerably within a fluence of 0.1 dpa, while weak intensities are observed up to a fluence of 1 dpa. These reflections disappear completely after a fluence of 2 dpa. The results are discussed within a model which considers both disordering and dissolution of precipitates under cascade producing irradiation.

Bourdeau, Françoise; Camus, Eric; Abromeit, Christian; Wollenberger, Heinrich

1994-12-01

203

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

204

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

205

Distribution of DNA fragment sizes after irradiation with ions  

NASA Astrophysics Data System (ADS)

Ionizing radiation is responsible for production of double-strand breaks (DSBs) in a DNA structure. In contrast to sparsely ionizing radiation, densely ionizing radiation produces DSBs that are non-randomly distributed along the DNA molecule and can form clusters of various size. The paper discusses minimalistic models that describe observable patterns of fragment length in DNA segments irradiated with heavy ions and applies the formalism to interpret the recent experimental data collected by use of atomic force microscope (AFM).

Gudowska-Nowak, E.; Psonka-Anto?czyk, K.; Weron, K.; Elsässer, T.; Taucher-Scholz, G.

2009-11-01

206

Escherichia coli mutants induced by multi-ion irradiation  

PubMed Central

Wild-type Escherichia coli K12 strain W3110 was irradiated by 10 keV nitrogen ions. Specifically, irradiation was performed six times by N+ ions, followed by the selection of lac constitutive mutants, and each time a stable S55 mutant was produced. By sequencing the whole genome, the fine map of S55 was completed. Compared with reference sequences, a total of eighteen single nucleotide polymorphisms (SNPs), two insertions and deletions (Indels), and nine structural variations (SVs) were found in the S55 genome. Among the 18 SNPs, 11 are transversional from A, T or C to G, accounting for 55.6% of point mutations. GCCA insertion occurs in the target gene lacI. Four SNPs, including three in rlpB and one in ygbN, are connected with cell envelope and transport. All nine structural variations of S55 are deletions and contain insertion sequence (IS) elements. Six deleted SVs contain disrupted ISs, nonfunctional pseudogenes, and one more 23 252 bp SV in the Rac prophage region. Overall, our results show that deletion bias observed in E. coli K12 genome evolution is generally related to the deletion of some nonfunctional regions. Furthermore, since ISs are unstable factors in a genome, the multi-ion irradiations that caused these deleted fragments in S55 turn out to be beneficial to genome stability, generating a wider mutational spectrum. Thus, it is possible that the mutation of these genes increases the ability of the E. coli genome to resist etch and damage caused by ion irradiation.

Song, Zhiqing; Luo, Liaofu

2012-01-01

207

Development of an ion beam alignment system for real-time scanning tunneling microscope observation of dopant-ion irradiation.  

PubMed

An ion beam alignment system has been developed in order to realize real-time scanning tunneling microscope (STM) observation of "dopant-ion" irradiation that has been difficult due to the low emission intensity of the liquid-metal-ion-source (LMIS) containing dopant atoms. The alignment system is installed in our original ion gun and STM combined system (IG/STM) which is used for in situ STM observation during ion irradiation. By using an absorbed electron image unit and a dummy sample, ion beam alignment operation is drastically simplified and accurized. We demonstrate that sequential STM images during phosphorus-ion irradiation are successfully obtained for sample surfaces of Si(111)-7x7 at room temperature and a high temperature of 500 degrees C. The LMIS-IG/STM equipped with the developed ion beam alignment system would be a powerful tool for microscopic investigation of the dynamic processes of ion irradiation. PMID:18681708

Kamioka, Takefumi; Sato, Kou; Kazama, Yutaka; Watanabe, Takanobu; Ohdomari, Iwao

2008-07-01

208

Development of an ion beam alignment system for real-time scanning tunneling microscope observation of dopant-ion irradiation  

SciTech Connect

An ion beam alignment system has been developed in order to realize real-time scanning tunneling microscope (STM) observation of 'dopant-ion' irradiation that has been difficult due to the low emission intensity of the liquid-metal-ion-source (LMIS) containing dopant atoms. The alignment system is installed in our original ion gun and STM combined system (IG/STM) which is used for in situ STM observation during ion irradiation. By using an absorbed electron image unit and a dummy sample, ion beam alignment operation is drastically simplified and accurized. We demonstrate that sequential STM images during phosphorus-ion irradiation are successfully obtained for sample surfaces of Si(111)-7x7 at room temperature and a high temperature of 500 deg. C. The LMIS-IG/STM equipped with the developed ion beam alignment system would be a powerful tool for microscopic investigation of the dynamic processes of ion irradiation.

Kamioka, Takefumi [Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku-ku, Tokyo 169-0051 (Japan); Sato, Kou; Kazama, Yutaka [Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Watanabe, Takanobu [Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Institute for Nanoscience and Nanotechnology, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Ohdomari, Iwao [Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan); Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku-ku, Tokyo 169-0051 (Japan); Institute for Nanoscience and Nanotechnology, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555 (Japan)

2008-07-15

209

Grain growth in Zr Fe thin films during in situ ion irradiation in a TEM  

Microsoft Academic Search

In situ ion-beam irradiation was used to study irradiation induced grain growth in co-sputter-deposited Zr\\/xFe (0% <= x <= 4.5%) nanocrystalline thin films. Samples were irradiated with 500 keV Kr ions to fluences in excess of 1016 ions\\/cm2 (on the order of 80 100 dpa), at irradiation temperatures ranging from 20 K to 573 K. The average grain size increased

D. Kaoumi; A. T. Motta; R. C. Birtcher

2006-01-01

210

An Irradiation Facility for In-Vacuum Heavy-Ion Irradiation of Large Area Superconductors  

NASA Astrophysics Data System (ADS)

An irradiation facility to irradiate ``long'' stripe-shaped high-Tc superconductors by means of GeV heavy ions is described. This facility was designed and installed at INFN - Laboratori Nazionali del Sud (LNS), Catania, Italy. It consists into a moving apparatus automatically driven at a given velocity in order to obtain the in-vacuum exposure of contiguous zones of the moving target at a programmed ion fluence. The whole apparatus is automatically controlled by a home-made remote control program. The main parts of the apparatus are the mechanical set-up and the electronic circuit to create feedback signals to control both the beam current and the velocity of the sample holder, the high accuracy system for the measure of the integrated charge and the beam calibration set-up (beam shape and homogeneity). This apparatus is, at our best knowledge, the first one especially designed to create nanostructures across ``large area'' superconducting devices by means of the irradiation. Some significant results of 4.2 GeV Au-ion irradiation of a long high-Tc superconducting multifilamentary Ag/BSCCO-2223 tape are shown.

Rovelli, A.; Amato, A.; Botta, D.; Chiodoni, A.; Gerbaldo, R.; Ghigo, G.; Gozzelino, L.; Laviano, F.; Negro, M.; Mezzetti, E.; Martini, L.; Curcio, F.

211

Influence of light-ion irradiation on the heavy-ion track etching of polycarbonate  

NASA Astrophysics Data System (ADS)

We report on the effect of light-ion irradiation on the size distribution of etched tracks produced by medium energy heavy-ions in polycarbonate. Makrofol KG polycarbonate foils were treated with 2 MeV H+ ions at different fluences ? either before or after a short irradiation with 18 MeV Au7+. The heavy ion irradiation was used to produce the latent tracks in the foils and the proton beam acted as a perturbation to the matrix. The proton irradiation causes initially a decrease in the mean etched pore size, as compared to samples only bombarded by Au ions, reaching a minimum at H+ fluences around 2-5×1013 cm-2, while at higher ? the pore size starts to grow again. This effect is attributed to the action of two competitive processes that dominate in different fluence regimes. The decrease in the pore radii at low fluences is attributed to an increase in crystallinity induced by the proton beam. As the total dose builds up, this effect is surpassed by chain scission and amorphization that grow at a lower rate and cause the pore radii to increase again.

Thomaz, R. S.; de Souza, C. T.; Papaléo, R. M.

2011-09-01

212

Post-irradiation deformation characteristics of heavy-ion irradiated 304L SS  

SciTech Connect

Post-irradiation deformation behavior in Ni-ion-irradiated 304L stainless steel (SS) is examined as a function of radiation dose and deformation temperature. For similar strain levels, specimens exhibit a transition from dislocation slip to deformation-induced twinning at 25C with increasing radiation dose. At 288C twinning is no longer observed and highly localized slip occurs by the formation of narrow ``channels`` containing a reduced defect density. The observations are discussed in terms of radiation-induced defect character and expected deformation mechanisms.

Cole, J.I. [Washington State Univ., Pullman, WA (United States); Bruemmer, S.M. [Pacific Northwest Lab., Richland, WA (United States)

1994-06-01

213

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

214

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

215

Characterization of polymeric films subjected to lithium ion beam irradiation  

NASA Astrophysics Data System (ADS)

Two different polymeric materials that are candidate materials for use as binders for mixed uranium-plutonium oxide nuclear fuel pellets were subjected to Li ion beam irradiation, in order to simulate intense alpha irradiation. The materials (a polyethylene glycol 8000 and a microcrystalline wax) were then analyzed using a combination of mass spectrometry (MS) approaches and X-ray photoelectron spectroscopy (XPS). Samples of the irradiated PEG materials were dissolved in H2O and then analyzed using electrospray ionization-MS, which showed the formation of a series of small oligomers in addition to intact large PEG oligomers. The small oligomers were likely formed by radiation-induced homolytic scissions of the C-O and C-C bonds, which furnish radical intermediates that react by radical recombination with H and OH. Surface analysis using SIMS revealed a heterogeneous surface that contained not only PEG-derived polymers, but also hydrocarbon-based entities that are likely surface contaminants. XPS of the irradiated PEG samples indicated the emergence of different carbon species, with peak shifts suggesting the presence of sp2 carbon atoms. Analysis of the paraffinic film using XPS showed the emergence of oxygen on the surface of the sample, and also a broadening and shifting of the C1s peak, demonstrating a change in the chemistry on the surface. The paraffinic film did not dissolve in either H2O or a H2O-methanol solution, and hence the bulk of the material could not be analyzed using electrospray. However a series of oligomers was leached from the bulk material that produced ion series in the ESI-MS analyses that were identified octylphenyl ethoxylate oligomers. Upon Li ion bombardment, these shifted to a lower average molecular weight, but more importantly showed the emergence of three new ion series that are being formed as a result of radiation damage. Surface analysis of the paraffinic polymers using SIMS produced spectra that were wholly dominated by hydrocarbon ion series, and no difference was observed between unirradiated and irradiated samples. The studies demonstrate that for the PEG-based polymers, direct evidence for radiolytic scission can be observed using ESI-MS, and suggests that both radiolytic pathways and efficiencies as a function of dose should be measurable by calibrating instrument response to the small oligomeric degradation products.

Groenewold, Gary S.; Cannon, W. Roger; Lessing, Paul A.; Avci, Recep; Deliorman, Muhammedin; Wolfenden, Mark; Akers, Doug W.; Jewell, J. Keith; Zuck, Larry D.

2013-02-01

216

Observation of Visible and Near-UV M1 Transitions from Highly Charged Kr, Mo and Xe Ions in LHD and its Prospect to Impurity Spectroscopy for D-T Burning Plasmas  

NASA Astrophysics Data System (ADS)

Magnetic dipole (M1) transitions from highly charged heavy impurities have been surveyed in visible and near-UV wavelength ranges longer than 2500 Å using a 1.33 m Czerny-Turner spectrometer in the Large Helical Device (LHD) for use in future visible impurity spectroscopy of D-T burning plasmas. The M1 transitions of KrXXII (Kr21+: P-like) 3s23p3 2D3/2-2D5/2 3463.75 ± 0.05 Å, KrXXIII (Kr22+: Si-like) 3s23p2 3P1-3P2 3841.07 ± 0.03 Å, MoXXIX (Mo28+: Si-like) 3s23p2 3P1-3P2 2842.10 ± 0.05 Å, XeXXXIII (Xe32+: Ti-like) 3d4 5D3-5D2 4139.01 ± 0.02 Å have been successfully observed using an external puff of Kr and Xe and an impurity pellet injection of Mo. As a result, the identication of the Ti-like XeXXXIII M1 transition, as observation for the first time in laboratory fusion plasmas, strongly suggests that the visible impurity spectroscopy of tungsten ions using Ti-like WLIII (W52+: 3626 Å) instead of the conventionally used EUV spectroscopy is possible in future D-T burning plasmas.

Katai, Ryuji; Morita, Shigeru; Goto, Motoshi

217

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

218

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

219

Ion irradiation damage in ilmenite at 100 K  

NASA Astrophysics Data System (ADS)

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 × 1015Ar2+/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.

1997-05-01

220

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

221

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

NASA Astrophysics Data System (ADS)

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.; Sofferman, D. L.; Beskin, I.; Chen, H. Y.; Thornton, K.; Goldman, R. S.

2013-08-01

222

Xe isotopic fractionation in a cathodeless glow discharge  

NASA Astrophysics Data System (ADS)

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.

1986-03-01

223

Efficient Synthesis of Gold Nanoparticles Using Ion Irradiation in Gas--Liquid Interfacial Plasmas  

NASA Astrophysics Data System (ADS)

The efficient synthesis of gold nanoparticles using plasma irradiation in gas--liquid interfacial discharges is carried out. The availability of plasma ion irradiation to an ionic liquid on nanoparticle synthesis was revealed by direct comparison with an electron shower system. It was found that the ion irradiation generated hydrogen radicals in the ionic liquid, which were effective for the synthesis of gold nanoparticles.

Baba, Kazuhiko; Kaneko, Toshiro; Hatakeyama, Rikizo

2009-03-01

224

Structural modifications of swift heavy ion irradiated PEN probed by optical and thermal measurements  

NASA Astrophysics Data System (ADS)

The present paper reports the effect of swift heavy ion irradiation on Polyethylene Naphthalate (PEN).Swift heavy ion irradiation introduces structural modification and degradation of PEN at different doses.Lower irradiation doses in PEN result in modification of structural properties and higher doses lead to complete degradation.Strong correlation between structural, optical, and thermal properties.

Devgan, Kusum; Singh, Lakhwant; Samra, Kawaljeet Singh

2013-07-01

225

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)

2011-12-09

226

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

227

Ion irradiation effects in natural garnets: Comparison with zircon  

NASA Astrophysics Data System (ADS)

The behavior of garnet (A3B2(XO4)3;Ia3d;Z=8) under ion-beam irradiation was investigated in order to compare its radiation susceptibility to another orthosilicate: zircon, ZrSiO4. Five natural end-member compositions were examined by in situ transmission electron microscopy during irradiation with 1.0 MeV Kr2+ over the temperature range of 50-1070 K. The critical amorphization temperature, above which amorphization does not occur, was 1030 K for andradite, but could not be determined for the other garnet composition because the Tc was higher than the highest temperature of the experiment. Based on topologic criterion, the degree of structural freedom in garnet is /~/-2.25 and for zircon /~/-1.5. Based on topology the critical amorphization dose for garnet should be higher than that of zircon; however, the average amorphization dose of garnet (0.20 dpa) is lower than that of zircon (0.37 dpa) at room temperature. This may be the result of the assumed value for the displacement energies, Ed, used in the calculation of dpa. Garnet did not decompose, while zircon decomposes to SiO2+ZrO2 during the ion irradiation at high temperature. This behavior may be related to the phase relations of garnet which melts congruently and zircon which decomposes to ZrO2+SiO2.

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

2002-05-01

228

Target Z dependence of Xe L x-ray emission in heavy ion-atom collision near the Bohr velocity: influence of level matching  

NASA Astrophysics Data System (ADS)

X-ray yields for the projectile L-shell have been measured for collisions between Xe20+ and thick solid targets throughout the periodic table with incident energies near the Bohr velocity. The yields show a very pronounced cyclic dependence on the target atomic number. This result indicates that Xe L x-ray emission intensity is greatly enhanced either in near-symmetric collisions or if the binding energy of the Xe M-shell matches the L- or N-shell binding energy of the target.

Ren, Jieru; Zhao, Yongtao; Zhou, Xianming; Cheng, Rui; Lei, Yu; Sun, Yuanbo; Wang, Xing; Xu, Ge; Wang, Yuyu; Liu, Shidong; Yu, Yang; Li, Yongfeng; Zhang, Xiaoan; Xu, Zhongfeng; Xiao, Guoqing

2013-09-01

229

Core dependence of electron emission in slow collisions of highly charged ions (Ar16+,Kr16+,Xe16+) with C60  

NASA Astrophysics Data System (ADS)

We present experimental results concerning an isocharge study of multielectronic capture and stabilization in slow collisions of Ar16+, Xe16+, Kr16+ with C60. Partial multicapture cross sections ?sr are given for all observed channels. The core effect only has an effect when the number of transferred electrons is sufficiently high. In this case, the stabilization ratio has been found equal to 4.2, 3.6, and 2.9 for Ar16+, Kr16+, and Xe16+, respectively. These measurements are qualitatively explained by fewer steps in the autoionization cascades for Xe than for Ar.

Bernard, J.; Brédy, R.; Martin, S.; Chen, L.; Désesquelles, J.; Buchet-Poulizac, M. C.

2002-07-01

230

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

231

The change in permeability spectra due to ion irradiation in the Co-based amorphous ribbon  

SciTech Connect

The Ar ion has been irradiated by an ion implanter with energy of 50, 70, and 100 keV and an ion dosage was set to 1.0x10{sup 17} ion/cm{sup 2} at a beam flux of 3.7 {mu}A/cm{sup 2}. The ion irradiation decreased the initial permeability and increased the relaxation frequency, and the behavior of permeability spectra due to ion irradiation was explained with damped harmonic model of domain wall on the general basis of magnetization mechanism. The ion irradiation gives rise to a significant change on the restoring force of domain wall but minor effect on the spin rotation. The enhancement in the permeability of the amorphous ribbon upon ion irradiation leads to a parallel improvement of giant magneto impedance response of the material, which is of practical use for sensing applications.

Park, D. G.; Song, H.; Cheong, Y. M. [Korea Atomic Energy Research Institute, Yuseong, P.O. Box 105, Daejeon 305-600 (Korea, Republic of); Park, C. Y. [Department of Physics, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, C. G. [Department of Materials Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2009-04-01

232

Dose response of alanine detectors irradiated with carbon ion beams  

SciTech Connect

Purpose: The dose response of the alanine detector shows a dependence on particle energy and type when irradiated with ion beams. The purpose of this study is to investigate the response behavior of the alanine detector in clinical carbon ion beams and compare the results to model predictions. Methods: Alanine detectors have been irradiated with carbon ions with an energy range of 89-400 MeV/u. The relative effectiveness of alanine has been measured in this regime. Pristine and spread out Bragg peak depth-dose curves have been measured with alanine dosimeters. The track structure based alanine response model developed by Hansen and Olsen has been implemented in the Monte Carlo code FLUKA and calculations were compared to experimental results. Results: Calculations of the relative effectiveness deviate less than 5% from the measured values for monoenergetic beams. Measured depth-dose curves deviate from predictions in the peak region, most pronounced at the distal edge of the peak. Conclusions: The used model and its implementation show a good overall agreement for quasimonoenergetic measurements. Deviations in depth-dose measurements are mainly attributed to uncertainties of the detector geometry implemented in the Monte Carlo simulations.

Herrmann, Rochus; Jaekel, Oliver; Palmans, Hugo; Sharpe, Peter; Bassler, Niels [Department of Physics and Astronomy, Aarhus University, 8000 Aarhus (Denmark); Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ) Heidelberg, 69120 Heidelberg (Germany) and Department of Experimental Clinical Oncology, Aarhus University Hospital, 8000 Aarhus (Denmark); Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ) Heidelberg, 69120 Heidelberg (Germany) and Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg University Hospital, 69120 Heidelberg (Germany); National Physical Laboratory, Teddington, Middlesex, TW 11 OLW (United Kingdom); Department of Physics and Astronomy, Aarhus University, 8000 Aarhus (Denmark); Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ) Heidelberg, 69120 Heidelberg (Germany) and Department of Experimental Clinical Oncology, Aarhus University Hospital, 8000 Aarhus (Denmark)

2011-04-15

233

Creation of nanodots on mica surfaces induced by highly charged xenon ions  

NASA Astrophysics Data System (ADS)

Experiments on nanostructure formation on muscovite mica surfaces irradiated by highly charged Xe29+ ions with a beam energy of 0.58 MeV and Xe30+ ions with two beam energies (0.6 MeV and 4.8 MeV) have been carried out on the 320 kV ECR platform at the Institute of Modern Physics (IMP), Lanzhou. The created nano-sized structures have been imaged using tapping mode atomic force microscopy. Hillock-like structures are clearly visible at the surface of the mica irradiated by Xe29+ ions (at 0.58 MeV) below the charge state threshold reported in earlier experimental investigations with a height (˜1.6 nm) nearly equal to the one observed by Xe30+ ions (at 0.6 MeV). Moreover when mica is irradiated by Xe30+ ions (at 4.8 MeV), regular nanodots have been observed with a surprisingly larger height of 3.3 nm, nearly the double than the one created by the impact of Xe30+ ions with kinetic energy of 0.6 MeV. The possible mechanism of insulator surface modification is discussed.

Wang, Yuyu; Zhao, Yongtao; Sun, Jianrong; Wang, Zhiguang; Liu, Jie; Li, Jinyu; Xiao, Guoqing

2012-09-01

234

Self-aligned nanostructures created by swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

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 SiNx 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 SiNx 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; Hofsäss, Hans; Krauser, Johann; Trautmann, Christina; Weidinger, Alois

2010-05-01

235

Compaction of microporous amorphous solid water by ion irradiation  

SciTech Connect

We have studied the compaction of vapor-deposited amorphous solid water by energetic ions at 40 K. The porosity was characterized by ultraviolet-visible spectroscopy, infrared spectroscopy, and methane adsorption/desorption. These three techniques provide different and complementary views of the structural changes in ice resulting from irradiation. We find that the decrease in internal surface area of the pores, signaled by infrared absorption by dangling bonds, precedes the decrease in the pore volume during irradiation. Our results imply that impacts from cosmic rays can cause compaction in the icy mantles of the interstellar grains, which can explain the absence of dangling bond features in the infrared spectrum of molecular clouds.

Raut, U.; Teolis, B. D.; Loeffler, M. J.; Vidal, R. A.; Fama, M.; Baragiola, R. A. [Laboratory of Atomic and Surface Physics (LASP), University of Virginia, Charlottesville, Virginia 22904 (United States)

2007-06-28

236

Compaction of microporous amorphous solid water by ion irradiation  

NASA Astrophysics Data System (ADS)

We have studied the compaction of vapor-deposited amorphous solid water by energetic ions at 40 K. The porosity was characterized by ultraviolet-visible spectroscopy, infrared spectroscopy, and methane adsorption/desorption. These three techniques provide different and complementary views of the structural changes in ice resulting from irradiation. We find that the decrease in internal surface area of the pores, signaled by infrared absorption by dangling bonds, precedes the decrease in the pore volume during irradiation. Our results imply that impacts from cosmic rays can cause compaction in the icy mantles of the interstellar grains, which can explain the absence of dangling bond features in the infrared spectrum of molecular clouds.

Raut, U.; Teolis, B. D.; Loeffler, M. J.; Vidal, R. A.; Famá, M.; Baragiola, R. A.

2007-06-01

237

Compaction of microporous amorphous solid water by ion irradiation.  

PubMed

We have studied the compaction of vapor-deposited amorphous solid water by energetic ions at 40 K. The porosity was characterized by ultraviolet-visible spectroscopy, infrared spectroscopy, and methane adsorption/desorption. These three techniques provide different and complementary views of the structural changes in ice resulting from irradiation. We find that the decrease in internal surface area of the pores, signaled by infrared absorption by dangling bonds, precedes the decrease in the pore volume during irradiation. Our results imply that impacts from cosmic rays can cause compaction in the icy mantles of the interstellar grains, which can explain the absence of dangling bond features in the infrared spectrum of molecular clouds. PMID:17614568

Raut, U; Teolis, B D; Loeffler, M J; Vidal, R A; Famá, M; Baragiola, R A

2007-06-28

238

Formation of Ge nanocrystals from ion-irradiated GeO2 nanocrystals by swift Ni ion beam  

NASA Astrophysics Data System (ADS)

GeO2 nanocrystal (NC) thin films were deposited on Si substrate using a magnetron sputtering method and irradiated with swift heavy ions of 80 MeV Ni at various fluences ranging from 5 × 1012 to 1 × 1014 ions/cm2. Grazing incidence X-ray diffraction measurements indicate the decrease in average size of NCs with increase in fluence of ion irradiation. Micro-Raman spectroscopy studies show clearly the formation of Ge NCs with the increase of irradiation fluence. Field emission scanning electron microscopy was employed to study the morphology and modifications in NCs due to ion irradiation. Transmission electron microscopy measurement of the ion-irradiated sample at 1 × 1014 ions/cm2 confirmed the presence of few nm-sized Ge NCs, which were not observed in as-deposited sample. The overall results suggest that GeO2 NCs are reduced in size and few of them are converted into Ge NCs due to the effects of electronic energy deposition by the irradiating ions. This formation of Ge NCs in the ion-irradiated GeO2 NC thin films has been understood on the basis of irradiation-induced separation of oxygen from GeO2 NCs.

Saikiran, V.; Srinivasa Rao, N.; Devaraju, G.; Chang, G. S.; Pathak, A. P.

2013-10-01

239

Analysis of cell-adhesion surface induced by ion-beam irradiation into biodegradable polymer  

NASA Astrophysics Data System (ADS)

Biodegradable polymers such as poly (L-lactic acid) (PLLA) are widely used to construct cell scaffolds for tissue engineering. We previously reported that cell attachment on a PLLA surface was improved by ion-beam irradiation. In this report, we attempted to characterize the cell-adhesion surface induced by ion-beam irradiation into PLLA by means of X-ray photoemission spectroscopy (XPS), Raman scattering measurement (Raman), and a fluorescence antibody technique. The substrates used were PLLA films; Ar+ ion-beam irradiation was performed at an energy of 50 keV with fluences of 1 × 1014 and 1 × 1015 ions/cm2. The results of XPS and Raman studies indicated the formation of new carbon structures and new functional groups by ion-beam irradiation. The protein adsorption was improved by Ar+ irradiation. We concluded that the cell-adhesion surface was induced as a consequence of production of new functional groups by ion-beam irradiation.

Yotoriyama, Tasuku; Nakao, Aiko; Suzuki, Yoshiaki; Tsukamoto, Takeyo; Iwaki, Masaya

2006-01-01

240

Thermal annealing study of swift heavy-ion irradiated zirconia  

Microsoft Academic Search

Sintered samples of monoclinic zirconia (alpha-ZrO2) have been irradiated at room temperature with 6.0 GeV Pb ions in the electronic slowing down regime. X-ray diffraction (XRD) and micro-Raman spectroscopy measurements showed unambiguously that a transition to the ``metastable'' tetragonal phase (beta-ZrO2) occurred at a fluence of 6.5×1012 cm-2 for a large electronic stopping power value (~32.5 MeV mum-1). At a

Jean-Marc Costantini; Andrée Kahn-Harari; François Beuneu; François Couvreur

2006-01-01

241

Ion beam irradiation induced fabrication of vertical coupling waveguides  

NASA Astrophysics Data System (ADS)

Vertically coupled waveguides have been fabricated on a silicon-on-insulator platform using a combination of reactive ion etching to pattern the device layer and high-energy proton beam irradiation followed by electrochemical etching to pattern the substrate. Infra-red light can be coupled from the lower rib waveguide within the substrate into the upper waveguide within the device layer. By varying the proton energy along the lower waveguide, we have fabricated a tapered profile which is thin at the coupling region for higher efficiency and thicker towards the outer ends for easier coupling of light. A typical coupling efficiency of 26% has been achieved.

Liang, H. D.; Kumar, V. S.; Wu, J. F.; Breese, M. B. H.

2013-04-01

242

Development and Testing of Ion-Irradiation under the Applied Stress for Nuclear Ceramics  

NASA Astrophysics Data System (ADS)

Simultaneous effects of the ion-irradiation and applied stress on the dimensional stability of SiC was studied up to 1 dpa at the irradiation temperature of 800°C. Tensioned surface of the curved SiC strips were irradiated using fixtures developed, and the irradiation creep strain of the irradiated samples was estimated from the irradiated curvatures. The irradiation creep rates were nearly proportional to the swelling rates. Linear relationship between the irradiation creep strain and stress was found below 1 dpa for the stress levels ranging 150-300 MPa.

Kondo, S.; Koyanagi, T.; Hinoki, T.

2011-10-01

243

Application of ion scattering spectroscopy to measurement of surface potential of MgO thin film under ion irradiation  

SciTech Connect

An experimental approach was proposed for the measurement of the surface potential (SP) induced on an insulator surface during ion irradiation by ion scattering spectroscopy (ISS). The resultant ISS spectra obtained for a MgO thin film of 600 nm thickness on a Si substrate under 950 eV He{sup +} irradiation revealed that the surface is positively charged by approximately 230 V. In addition, the onset energy of a secondary ion peak indicated a SP of approximately 205 V. The present results confirmed that ISS is an effective technique for measuring the SP during ion irradiation.

Nagatomi, T.; Kuwayama, T.; Takai, Y. [Department of Material and Life Science, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); Yoshino, K.; Morita, Y.; Kitagawa, M. [Panasonic AVC Networks Company, Matsushita Electric Industrial Co., Ltd., Ibaraki, Osaka 567-0026 (Japan); Nishitani, M. [Matsushita Electric Industrial Co., Ltd., Moriguchi, Osaka 570-8501 (Japan)

2008-02-25

244

Diamond-like carbon sputtering by laser produced Xe plasma  

NASA Astrophysics Data System (ADS)

The sputtering of diamond-like carbon (DLC) was investigated using Xe ion bombardment from the laser plasma X-ray source (LPX). The LPX we developed uses a solid Xe target and emits UV–X-rays and Xe ions. Using the LPX as an ion source, we measured etching depths of DLC, Ru, and Au films using a quartz crystal microbalance (QCM) to determine their ion sputtering rates at incident angles of 0° and 70°. The calculated results by the SRIM code were able to predict the measured results, except for the case of the DLC film at 0° incident. Our measured result indicated that the DLC sputtering at 0° was ten times larger than previously reported data, in which an ion gun was used. We consider that the difference was a characteristic effect of the laser plasma, and can be explained as a synergistic effect of ion bombardment and UV radiation from the Xe plasma.

Amano, Sho; Inoue, Tomoaki

2013-11-01

245

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

246

Dielectric response of polyethersulphone (PES) polymer irradiated with 145 MeV Ne6+ ions  

NASA Astrophysics Data System (ADS)

Heavy ion irradiation produces modifications in polymers and adapts their electrical, chemical and optical properties in the form of rearrangement of bonding, cross-linking, chain scission and formation of carbon rich clusters. Modification depends on the ion, its energy and fluence and the polymeric material. In the present work, a study of the dielectric response of pristine and heavy ion irradiated Polyethersulphone (PES) polymer film is carried out. 250 ?m thick PES films were irradiated to the fluences of 1012 and 1013 ions/cm2 with Ne6+ ions of 145 MeV energy from Variable Energy Cyclotron Centre, Kolkata On irradiation with heavy ions dielectric constant (?') decreases at higher frequencies and increases with fluences. Variation of loss factor (tan ?) with frequency for pristine and irradiated with Si ions reveals that tan ? increases as the frequency increases. The tan? also increases with fluence. Tan ? has positive values indicating the dominance of inductive behavior.

Ali, S. Asad; Kumar, Rajesh; Khan, Wasi; Naqvi, A. H.; Prasad, R.

2013-02-01

247

Grain growth in Zr–Fe thin films during in situ ion irradiation in a TEM  

Microsoft Academic Search

In situ ion-beam irradiation was used to study irradiation induced grain growth in co-sputter-deposited Zr\\/xFe (0%?x?4.5%) nanocrystalline thin films. Samples were irradiated with 500keV Kr ions to fluences in excess of 1016ions\\/cm2 (on the order of 80–100dpa), at irradiation temperatures ranging from 20K to 573K. The average grain size increased monotonically with ion fluence until it reached a saturation value

D. Kaoumi; A. T. Motta; R. C. Birtcher

2006-01-01

248

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

249

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

250

In vitro degradation properties of ion-beam irradiated poly(lactide-co-glycolic acid) mesh  

NASA Astrophysics Data System (ADS)

Scaffolds for tissue regeneration must be biocompatible and biodegradable. Ion-beam irradiation is useful for making polymers biocompatible, but the process by which the irradiated polymers biodegradable is not yet well understood. We investigated this phenomenon by Kr + -irradiated poly(lactide-co-glycolic acid) (PLGA) mesh substrate at an acceleration energy of 50 keV with fluences of 1 × 10 13 and 1 × 10 14 ions/cm 2 . We then measured the electronic states of the constituent elements on the irradiated surface by X-ray photoelectron microscopy (XPS) and evaluated the hydrolytic degradation properties (weight loss, media pH, and tensile strength) of the mesh in phosphate buffer solution. New functional groups and carbonization were induced on the irradiated surface. Degradation rate and tensile strength remain unchanged by ion-beam irradiation. Ion-beam irradiation should, thus, be a promising modification technique for tissue engineering scaffolds.

Tanaka, Toshiyuki; Tsuchiya, Koji; Yajima, Hirofumi; Suzuki, Yoshiaki; Fukutome, Akira

2011-10-01

251

Data acquisition system for light-ion irradiation creep experiment.  

SciTech Connect

Software was developed for a PDP11V/03-based data acquisition system to support the Light-Ion Irradiation Creep Experiment installed at the University of Washington Tandem Van de Graaff Accelerator. The software consists of a real-time data acquisition and storage program, DAC04, written in assembly language. This program provides for the acquisition of up to 30 chennels at 100 Hz, data averaging before storage on disk, alarming, data table display, and automatic disk switching. All analog data are acquired via an analog-to-digital converter subsystem having a resolution of 14 bits, a maximum throughput of 20 kHz, and an overall system accuracy of +-0.01%. These specifications are considered essential for the long-term measurement of irradiation creep strains and temperatures during the light-ion bombardment of irradiation creep specimens. The software package developed also contains a collection of FORTRAN programs designed to monitor a test while in progress. These programs use the foreground/background feature of the RT-11 operating system. The background programs provide a variety of services. The program, GRAFTR, allows transient data (i.e., prior to averaging) to be graphed at the graphics terminal. The program, GRAFAV, allows averaged data to be read from disk and displayed graphically at the terminal. The program, TYPAV, reads averaged data from disk and displays it at the terminal in tabular form. Other programs allow text messages to be written to disk, read from disk, and allow access to DAC04 initialization data. 5 figures, 18 tables.

Hendrick, P.L.; Whitaker, T.J.

1979-07-01

252

Study of intermixing and Zr-silicide formation using swift heavy ion irradiation  

Microsoft Academic Search

Swift heavy ion (SHI) beam induced irradiation is an established technique for investigating structural modifications in thin films depending\\u000a on the S\\u000a e sensitivity of material. Intermixing due to 120 MeV Au ion irradiation at different fluences from 1012 to 1014 ions\\/cm2 has been reported as a function of ion fluence in a-Si\\/Zr\\/a-Si thin films on Si substrate. The samples

Garima Agarwal; Vaibhav Kulshrestha; Renu Dhunna; D. Kabiraj; Shikha Verma; I. P. Jain

2010-01-01

253

Studies of Xenon Chlorides and Other Xenon Compounds by the Mo¨ssbauer Effect in 129Xe  

Microsoft Academic Search

The compounds XeCl2 and XeCl4 have been made in the beta decay of ICl2? and ICl4? containing radioactive 129I. The electric quadrupole interaction in the 39.6-keV excited state of the 129Xe nucleus is employed to study these substances by the Mo¨ssbauer effect. The decay products are compared with XeF2 and XeF4 and with the parent ions. It is shown that

G. J. Perlow; M. R. Perlow

1968-01-01

254

Determination of ion track radii in amorphous matrices via formation of nano-clusters by ion-beam irradiation  

SciTech Connect

We report on a method for the determination of ion track radii, formed in amorphous materials by ion-beam irradiation. The method is based on the addition to an amorphous matrix of a small amount of foreign atoms, which easily diffuse and form clusters when the temperature is sufficiently increased. The irradiation causes clustering of these atoms, and the final separations of the formed clusters are dependent on the parameters of the ion-beam. Comparison of the separations between the clusters that are formed by ions with different properties in the same type of material enables the determination of ion-track radii.

Buljan, M.; Karlusic, M.; Bogdanovic-Radovic, I.; Jaksic, M.; Radic, N. [Rudjer Boskovic Institute, Bijenicka cesta 54, 10000 Zagreb (Croatia); Salamon, K. [Institute of Physics, 10000 Zagreb (Croatia); Bernstorff, S. [Sincrotrone Trieste, 34102 Basovizza (Italy)

2012-09-03

255

Divacancy acceptor levels in ion-irradiated silicon  

SciTech Connect

High-purity {ital n}-type silicon samples have been irradiated with mega-electron-volt ions ({sup 1}H{sup +}, {sup 4}He{sup 2+}, {sup 16}O{sup 4+}, {sup 32}S{sup 7+}, {sup 79}Br{sup 8+}, and {sup 127}I{sup 10+}), and the two divacancy-related acceptor levels {similar to}0.23 and {similar to}0.42 eV below the conduction band ({ital E}{sub {ital c}}), respectively, have been studied in detail using deep-level transient spectroscopy (DLTS). Depth concentration profiles show identical values for the two levels at shallow depths, while in the region close to the damage peak large deviations from a one-to-one proportionality are found. These deviations increase with ion dose and also hinge strongly on the density of energy deposited into elastic collisions per incoming ion. Evidence for a model of the two levels is presented and, in particular, the model invokes excited states caused by motional averaging and lattice strain associated with damaged regions.

Svensson, B.G.; Mohadjeri, B. (The Royal Institute of Technology, Solid State Electronics, P.O. Box 1298, S-16428 Kista-Stockholm, Sweden (SE)); Hallen, A. (Department of Radiation Sciences, Uppsala University, P.O. Box 535, S-75121 Uppsala, Sweden (SE)); Svensson, J.H. (Department of Physics and Measurement Technology, University of Linkoeping, S-58183 Linkoeping, Sweden (SE)); Corbett, J.W. (Department of Physics, The State University of New York at Albany, Albany, New York 12222 (US))

1991-01-15

256

Analysis of grain growth due to ion irradiation of thin films  

Microsoft Academic Search

It has been reported recently that ion irradiation of thin films can lead to grain growth. In this paper, an analysis of grain growth in ion-irradiated thin films is discussed. It is based on establishing an analogy with thermally-activated grain growth. Recently reported experimental results are used to test the validity of the analysis.

A. M. Ibrahim

1988-01-01

257

Effect of ion irradiation on the properties of carbon nanotube buckypapers  

Microsoft Academic Search

Optical, electrical and structural properties of argon (Ar) ion-irradiated buckypapers of multi-walled carbon nanotube (MWCNT) at various doses prepared by a vacuum filtration method were investigated. It was found that the direct current (DC) conductivity and absorption spectra in the visible range were decreased with an increasing Ar ion irradiation dose. A subsequent heating of nanotube buckypapers at 800 K

Ahmad Ishaq; A. R. Sobia; Long Yan

2010-01-01

258

HRTEM and FTIR investigation of nanosized zinc ferrite irradiated with 100 MeV oxygen ions.  

PubMed

Present work aims to investigate effect of 100 MeV oxygen ion irradiation on the vibrational modes of zinc ferrite nanoparticles. Nanosize zinc ferrite systems of different crystallite size ranging from 12-62 nm were irradiated at the fluence of 1×10(13) and 5×10(13) ions/cm(2). High resolution transmission electron micrograph study indicates the structural disorder induced by ion irradiation. Bands corresponding to various vibrational modes in Fourier transform infrared spectra exhibit changes and are affected by the crystallite size/microstructure of pristine samples. The irradiation induced changes are dominated for sample ZF1000. PMID:23434561

Singh, Jitendra Pal; Dixit, Gagan; Srivastava, R C; Negi, Puneet; Agrawal, H M; Kumar, Ravi

2013-01-10

259

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

260

In-situ observations of the development of heavy-ion damage in semiconductors  

SciTech Connect

In-situ observations on ion-beam induced amorphisation of GaAs, GaP and Si are reported. Direct-impact amorphisation was found to occur in GaAs irradiated with 100-keV Xe/sup +/ ions to low doses at low temperature (approx. 40K) in contrast to previous room temperature irradiations. In GaP and in silicon, where heavy projectiles do cause direct impact amorphisation at room temperature, the evolution of the damage structure with ion-dose was studied. The defect yield both in GaP irradiated with 100-keV Kr/sup +/ ions and in Si irradiated with 100-keV Xe/sup +/ ions was found to decrease monotonically with increasing dose over the dose range 10/sup 15/ to 10/sup 17/ ions m/sup -2/.

Jenkins, M.L.; Chandler, T.J.; Robertson, I.M.; Kirk, M.A.

1985-01-01

261

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

262

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

SciTech Connect

Single crystal plates of ferrimagnetic yttrium iron garnet (111)-YIG:Si (Y{sub 3}Fe{sub 4.94}Si{sub 0.06}O{sub 12}) and barium hexaferrite (00.1)-BaM (BaFe{sub 12}O{sub 19}) or (00.1)-BaM:Co,Ti (BaFe{sub 9.1}Co{sub 1.4}Ti{sub 1.5}O{sub 19}) are irradiated with swift heavy ions (3.8 GeV {sup 129}Xe or 6.0 GeV {sup 208}Pb) in the electronic slowing down regime, above the threshold ({approximately}20 keV nm{minus}1) of formation of continuous and homogeneous cylindrical amorphous tracks. The modifications of the magnetic properties are studied by {sup 57}Fe Moessbauer 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 Moessbauer 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 Moessbauer spectra under a magnetic field applied in the sample (111) plane which rotates the magnetization back to the easy {l_angle}111{r_angle} 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 Moessbauer 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 Moessbauer 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. {copyright} 2001 American Institute of Physics.

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

2001-07-01

263

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

264

Complex chromatid-isochromatid exchanges following irradiation with heavy ions?  

PubMed

We describe a peculiar and relatively rare type of chromosomal rearrangement induced in human peripheral lymphocytes that were ostensibly irradiated in G(0) phase of the cell cycle by accelerated heavy ions, and which, to the best of our knowledge, have not been previously described. The novel rearrangements which were detected using mFISH following exposure to 500 MeV/nucleon and 5 GeV/n 56Fe particles, but were not induced by either 137Cs gamma rays or 238Pu alpha particles, can alternatively be described as either complex chromatid-isochromatid or complex chromatid-chromosome exchanges. Different mechanisms potentially responsible for their formation are discussed. PMID:15162039

Loucas, B D; Eberle, R L; Durante, M; Cornforth, M N

2004-01-01

265

Highly sensitive urea sensing with ion-irradiated polymer foils  

NASA Astrophysics Data System (ADS)

Recently we prepared urea-sensors by attaching urease to the inner walls of etched ion tracks within thin polymer foil. Here, alternative track-based sensor configurations are examined where the enzyme remained in solution. The conductivities of systems consisting of two parallel irradiated polymer foils and confining different urea/urease mixtures in between were examined. The correlations between conductivity and urea concentration differed strongly for foils with unetched and etched tracks, which points at different sensing mechanisms - tentatively attributed to the adsorption of enzymatic reaction products on the latent track entrances and to the enhanced conductivity of reaction product-filled etched tracks, respectively. All examined systems enable in principle, urea sensing. They point at the possibility of sensor cascade construction for more sensitive or selective sensor systems.

Fink, Dietmar; Muñoz Hernandez, Gerardo; Alfonta, Lital

2012-02-01

266

Comparison of swelling for structural materials on neutron and ion irradiation  

SciTech Connect

The swelling of V-base alloys, Type 316 stainless steel, Fe-25Ni-15Cr alloys, ferritic steels, Cu, Ni, Nb-1% Zr, and Mo on neutron irradiation is compared with the swelling for these materials on ion irradiation. The results of this comparison show that utilization of the ion-irradiation technique provides for a discriminative assessment of the potential for swelling of candidate materials for fusion reactors.

Loomis, B.A.

1986-03-01

267

Influence of the crystallite size on the phase transformation of yttria irradiated with swift heavy ions  

Microsoft Academic Search

:   The irradiation effects induced by swift heavy ions are now widely described in `bulk' materials. It is shown here that the\\u000a behaviour of matter under irradiation depends on its crystalline state in the sense that a given material is all the more\\u000a sensitive to swift heavy ion irradiations as the mean crystallite size L is small. The present paper

S. Hémon; A. Berthelot; Ch. Dufour; F. Gourbilleau; E. Dooryhée; S. Bégin-Colin; E. Paumier

2001-01-01

268

Using HaXe  

Microsoft Academic Search

haXe is a high-level programming language for web development. It can be compiled into .js files for JavaScript developers\\u000a or into .swf files for Flash, and it also supports the Neko virtual machine. Before going into the details of haXe, I’ll explain\\u000a how it came to be and how it is related to the evolution of Flash, ActionScript, and some

Nicolas Cannasse

269

Liquid xe (ar) Low-Background Detectors, Russian Activities  

NASA Astrophysics Data System (ADS)

Short review of low background experiments with liquid Xe (Ar) detectors is done. Possibilities of liquid CD4 and (Ar + CD4) detectors for solar neutrino experiments are discussed. Results with "ion sweeper" are presented.

Barabash, A. S.

2002-01-01

270

Structural and electrical evolution of He ion irradiated hydrocarbon films observed by conductive atomic force microscopy  

NASA Astrophysics Data System (ADS)

Polymer-like hydrocarbon films are irradiated with 100 keV He ion at the fluences of 1.0 × 1015-1.0 × 1017 ions/cm2 or at the irradiation temperature ranging from 25 to 600 °C. Conductive atomic force microscopy (CAFM) has been used to evaluate the nanoscale electron conducting properties of these irradiated hydrocarbon films. Nanoscale and conducting defects have been formed in the hydrocarbon films irradiated at a relatively high ion fluence (1.0 × 1017 ions/cm2) or an elevated sample temperature. Analysis indicates that He ion irradiation results in the evolution of polymer-like hydrocarbon into a dense structure containing a large fraction of sp2 carbon clusters. The sp2 carbon clusters formed in irradiated hydrocarbon films can contribute to the formation of filament-like conducting channels with a relatively high local field-enhancing factor. Measurements indicate that the growth of nanoscale defects due to He ion irradiation can result in the surface swelling of irradiated hydrocarbon films at a relatively high ion fluences or elevated temperature.

Fan, Hongyu; Yang, Deming; Sun, Li; Yang, Qi; Niu, Jinhai; Bi, Zhenhua; Liu, Dongping

2013-10-01

271

Shape transformation of Sn nanocrystals induced by swift heavy-ion irradiation and the necessity of a molten ion track  

SciTech Connect

We report on the spherical to rodlike shape transformation of Sn nanocrystals (NCs) embedded in amorphous SiO{sub 2} following irradiation with 185 MeV Au ions. Consistent with previous reports for other metals, transmission electron microscopy demonstrates that under irradiation, Sn NCs larger than a critical size (11 nm) elongate parallel to the incident ion direction, while smaller particles remain spherical. Irradiation-induced NC dissolution is significant, as evident from the formation of smaller NCs in place of their original larger counterparts. Using formation conditions that yield Sn NCs at the amorphous-SiO{sub 2}/crystalline-Si interface, we show that the irradiation-induced shape change occurs only within the SiO{sub 2} layer, in the direction opposite to that of the incident ions. We suggest this demonstrates the necessity of a molten ion track and provides further evidence for an elongation process involving NC melting and flow.

Giulian, R.; Araujo, L. L.; Sprouster, D. J.; Kluth, P.; Byrne, A. P.; Ridgway, M. C. [Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Kremer, F.; Fichtner, P. F. P. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Ciaxa Postal 1501, CEP 91501-970, Porto Alegre, Rs (Brazil)

2010-09-15

272

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

273

Structural modifications of low-energy heavy-ion irradiated germanium  

NASA Astrophysics Data System (ADS)

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 ?=7? and ?=45?. 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 ?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.; Kluth, P.; Ridgway, M. C.; Wesch, W.

2011-09-01

274

Ion-irradiation-induced damage in Fe–Cr alloys characterized by nanoindentation  

Microsoft Academic Search

Self-ion irradiation in combination with nanoindentation offers the possibility to characterize irradiation damage in a broad range of irradiation temperature and fluence. Nanoindentation results are reported for Fe–2.5at.%Cr, Fe–9at.%Cr and Fe–12.5at.%Cr irradiated at room temperature, 300°C and 500°C. Special features of this work are roughly rectangular damage profiles and exploitation of the full load dependence of hardness. The effects of

C. Heintze; F. Bergner; M. Hernández-Mayoral

2011-01-01

275

Thickness dependent effect of swift heavy ion irradiation in W\\/Ni superlattice multilayers  

Microsoft Academic Search

This study reports on the layer thickness dependent effect of swift heavy ion irradiation (SHI) in W\\/Ni multilayer structures (MLS) having bilayer compositions of [W(25 Å)\\/Ni(25 Å)], [W(40 Å)\\/Ni(40 Å)] and [W(34 Å)\\/Ni(57 Å)] of 10-bilayers. These were grown on [1 0 0]-silicon using ion-beam sputtering. The pristine MLS were subjected to 120 MeV Au9+ ion irradiation up to a

Sharmistha Bagchi; F. Singh; D. K. Avasthi; N. P. Lalla

2009-01-01

276

Thickness dependent effect of swift heavy ion irradiation in W\\/Ni superlattice multilayers  

Microsoft Academic Search

This study reports on the layer thickness dependent effect of swift heavy ion irradiation (SHI) in W\\/Ni multilayer structures (MLS) having bilayer compositions of [W(25 ?)\\/Ni(25 ?)], [W(40 ?)\\/Ni(40 ?)] and [W(34 ?)\\/Ni(57 ?)] of 10-bilayers. These were grown on [1 0 0]-silicon using ion-beam sputtering. The pristine MLS were subjected to 120 MeV Au9+ ion irradiation up to a

Sharmistha Bagchi; F Singh; D K Avasthi; N P Lalla

2009-01-01

277

Structural phase diagram for ZnS nanocrystalline thin films under swift heavy ion irradiation  

Microsoft Academic Search

The synthesis of nanocrystalline ZnS thin films by pulsed laser deposition and their modification by swift heavy ions are presented. The irradiations with 150MeV Ni ions at fluences of 1×1011, 1×1012 and 1×1013ions\\/cm2 have been used for these studies. Irradiation results in structural phase transformation and bandgap modification of these films are investigated by using X-ray diffraction and UV–visible absorption

Shiv P. Patel; S. A. Khan; A. K. Chawla; R. Chandra; J. C. Pivin; D. Kanjilal; Lokendra Kumar

2011-01-01

278

Swift heavy-ion irradiation effects on electrical and defect properties of NPN transistors  

Microsoft Academic Search

NPN transistors were irradiated by 95 MeV oxygen ions in a fluence ranging from 5 × 1010 to 5 × 1012 ions cm-2. The dc current gain (hFE), excess base current (DgrIB = IBpost - IBpre), excess collector current (DgrIC = ICpost - ICpre) and collector-saturation current (ICS) of the ion-irradiated transistors were studied systematically. We found that both hFE

A. P. Gnana Prakash; S. C. Ke; K. Siddappa

2004-01-01

279

Swift heavy ion irradiation-induced structural and conformational changes in polypyrrole nanofibers  

Microsoft Academic Search

In the present paper, we report a detailed analysis of the fluence-dependent conformational and structural changes induced in the polypyrrole nanofibers (PPy NFs) upon swift heavy ion (SHI) irradiation. PPy NFs, synthesized using a cationic surfactant cetyltrimethylammonium bromide-assisted micellar polymerization technique, have been irradiated with 90 MeV O ions at normal beam incidence with fluence varying from 3×10 to 1×10 ions\\/cm using

Somik Banerjee; A. Kumar

2011-01-01

280

Swift heavy-ion irradiation effects on electrical and defect properties of NPN transistors  

Microsoft Academic Search

NPN transistors were irradiated by 95 MeV oxygen ions in a fluence ranging from 5 × 1010 to 5 × 1012 ions cm?2. The dc current gain (hFE), excess base current (?IB = IBpost ? IBpre), excess collector current (?IC = ICpost ? ICpre) and collector-saturation current (ICS) of the ion-irradiated transistors were studied systematically. We found that both hFE

A P Gnana Prakash; S C Ke; K Siddappa

2004-01-01

281

Ion-irradiation-induced grain growth and lateral thin-film reactions  

Microsoft Academic Search

Ion-irradiation-induced grain growth was investigated in a variety of thin metal films. For most of the cases, irradiations are performed at several hundred keV and incident ions are inert gases. In terms of dose, grain growth is characterized by growth and saturation regimes. In the growth regime, the increase of average grain size and with ion dose obeys a power

1989-01-01

282

Study of modifications in Lexan polycarbonate induced by swift O 6+ ion irradiation  

Microsoft Academic Search

Swift Heavy Ion (SHI) irradiation of the polymeric materials modifies their physico-chemical properties. Lexan polycarbonate films were irradiated with 95MeV oxygen ions to the fluences of 1010, 1011, 1012, 1013 and 2×1013ions\\/cm2. Characterization of optical, chemical, electrical and structural modifications were carried out by UV–Vis spectroscopy, FTIR spectroscopy, Dielectric measurements and X-ray Diffraction. A shift in the optical absorption edge

S. Asad Ali; Rajesh Kumar; F. Singh; P. K. Kulriya; Rajendra Prasad

2010-01-01

283

Tailoring magnetism in CoNi films with perpendicular anisotropy by ion irradiation  

SciTech Connect

This paper reports on the influence of ion irradiation on the magnetic properties of Co/Ni multilayers with perpendicular magnetic anisotropy (PMA). This material is a very promising candidate for ultrahigh density spintronic applications since it exhibits high polarization and low damping parameters. We show that PMA can be tailored in a controlled way by using uniform He{sup +} ion irradiation or focused Ga{sup +} ion beam.

Stanescu, D.; Ravelosona, D.; Mathet, V.; Chappert, C. [Institut d'Electronique Fondamentale, UMR CNRS 8622, Universite Paris Sud, 91405 Orsay Cedex (France); Samson, Y.; Beigne, C. [CEA Grenoble, DRFMC/SP2M, 17 avenue des Martyrs, 38054 Grenoble (France); Vernier, N.; Ferre, J. [Laboratoire de Physique de Solide, UMR CNRS 8502, Universite Paris Sud, 91405 Orsay Cedex (France); Gierak, J.; Bouhris, E. [Laboratoire de Photonique et de Nanostructures-CNRS, route de Nozay, 91460 Marcoussis (France); Fullerton, E. E. [Center for Magnetic Recording Research, University of California, San Diego, La Jolla, California 92093-0401 (United States)

2008-04-01

284

Nanogroove formation by ion irradiation on indentation-modified amorphous SiO(2).  

PubMed

Ion beams are widely used for micro/nanostructure fabrication with unique features of the energetic processes. In this work, we present a self-assembled nanostructure fabrication by ion irradiation with a patterned strain/stress field. The patterned strain/stress field is introduced by micro-Vickers indentation to amorphous SiO(2) (load = 100 mN). After irradiation of 60 keV Cu(-) ions, nanogrooves (width from 150 to 250 nm) were created at the indentation edge. Under the ion irradiation of a constant ion flux, the nanogroove size linearly increased with ion fluence from 2 × 10(16) to 1.2 × 10(17) ions cm(-2). Comparison of indented samples after irradiation and thermal annealing suggests that the nanogrooving originates from ion beam interactions with residual stress/strain by indentation and that a non-thermal effect results from the ion irradiation processes. Cross-sectional TEM analysis showed that the grooves extend over 200 nm below the surface, implying that the groove growth is not caused by surface diffusion. It is concluded from the results that the grooving is due to irradiation-induced mass transport accompanied by vacancy aggregation at the interface between the indented and non-indented areas. PMID:21832550

Pan, J; Takeda, Y; Amekura, H; Nakayama, Y; Song, M; Kishimoto, N

2008-08-05

285

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

286

Effects of irradiation of energetic heavy ions on digital pulse shape analysis with silicon detectors  

NASA Astrophysics Data System (ADS)

The next generation of 4? detector arrays for heavy ion studies will largely use Pulse Shape Analysis to push the performance of silicon detectors with respect to ion identification. Energy resolution and pulse shape identification capabilities of silicon detectors under prolonged irradiation by energetic heavy ions have thus become a major issue. In this framework, we have studied the effects of irradiation by energetic heavy ions on the response of neutron transmutation doped (nTD) silicon detectors. Sizeable effects on the amplitude and the risetime of the charge signal have been found for detectors irradiated with large fluences of stopped heavy ions, while much weaker effects were observed by punching-through ions. The robustness of ion identification based on digital pulse shape techniques has been evaluated.

Barlini, S.; Carboni, S.; Bardelli, L.; Le Neindre, N.; Bini, M.; Borderie, B.; Bougault, R.; Casini, G.; Edelbruck, P.; Olmi, A.; Pasquali, G.; Poggi, G.; Rivet, M. F.; Stefanini, A. A.; Baiocco, G.; Berjillos, R.; Bonnet, E.; Bruno, M.; Chbihi, A.; Cruceru, I.; Degerlier, M.; Dueñas, J. A.; Galichet, E.; Gramegna, F.; Kordyasz, A.; Kozik, T.; Kravchuk, V. L.; Lopez, O.; Marchi, T.; Martel, I.; Morelli, L.; Parlog, M.; Piantelli, S.; Petrascu, H.; Rosato, E.; Seredov, V.; Vient, E.; Vigilante, M.; FAZIA Collaboration

2013-04-01

287

Effect of ion irradiation on the interdiffusion growth of aluminide phases in Ti Al diffusion couple  

NASA Astrophysics Data System (ADS)

During annealing on the Ti surface coated by the Al film, different aluminide phases were formed as the result of reactions between Ti and Al. Preliminary irradiation of the Al film with the thickness of 7 ?m by Ti+ ions had a strong effect on the interdiffusion growth of aluminide phases on the Ti substrate. Preliminary ion irradiation resulted in the development of more homogeneous and fine-grain microstructure during subsequent annealing. During ion irradiation of the two-phase (TiAl + Ti3Al) overlayer the decomposition of the TiAl compound and the formation of Ti3Al happened. In the processing of subsequent annealing, diffusion cementation of the overlayer occurred faster on the surface of the irradiated samples. After irradiation by different ions (Ti+ and Al+), and during subsequent annealing the kinetics of structural formation developed in a different way.

Romankov, S. E.; Mamaeva, A.; Vdovichenko, E.; Ermakov, E.

2005-08-01

288

Nanohole pattern formation on germanium induced by focused ion beam and broad beam Ga{sup +} irradiation  

SciTech Connect

Hexagonally ordered nanohole patterns were produced on Ge(100) surfaces by focused Ga{sup +} ion beam and broad Ga{sup +} ion beam irradiations with 5 keV energy under normal incidence. Identical patterns were obtained by irradiations with a scanning focused ion beam under different irradiation conditions and with a broad Ga{sup +} beam without scanning and five orders of magnitude smaller ion flux. Thus, we could demonstrate that nanohole pattern formation is independent of ion flux over several orders of magnitude and scanning of a focused ion beam under appropriate conditions is identical to broad ion beam irradiation.

Fritzsche, Monika; Muecklich, Arndt; Facsko, Stefan [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany)

2012-05-28

289

Effect of irradiation by heavy ions on the nanostructure of perspective materials for nuclear power plants  

NASA Astrophysics Data System (ADS)

An imitation experimental technique on the irradiation with heavy ions of structural materials of nuclear power plants using tomographic atom probe analysis has been elaborated. The scheme of irradiation of specimens for atom probe analysis has been realized on a MEVVA ion source of an TIPr accelerator (ITEP) with ion energy 75 keV per charge. Test experiments with irradiation and analysis of samples of the EK-181 steel by aluminum ions to a fluence of ˜2 × 1015 ion/cm2 have been performed. Experiments on the Fe-ion irradiation of the samples of ODS EUROFER perspective steel for fission and fusion reactors to different damaging doses have been carried out. The analysis of distribution of different chemical elements in the volumes tested has revealed that under ion irradiation a change in the composition of nanosized clusters, which are present in the initial material takes place. Comparison of the data obtained with the results of reactor irradiation of the ODS EUROFER steel has been carried out. These data testify a correspondence between nanoscale changes in the steels oxide dispersion strengthened in imitation experiments and under the conditions of reactor irradiation.

Rogozhkin, S. V.; Aleev, A. A.; Zaluzhnyi, A. G.; Kuibida, R. P.; Kulevoi, T. V.; Nikitin, A. A.; Orlov, N. N.; Chalykh, B. B.; Shishmarev, V. B.

2012-02-01

290

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

291

Improved photoelectrochemical response of haematite by high energy Ag9+ ions irradiation  

NASA Astrophysics Data System (ADS)

Haematite (?-Fe2O3) thin films deposited on a conducting glass substrate were irradiated with 120 MeV Ag9+ ions with increasing ion fluences. Their structural evolution was determined by x-ray diffraction and Raman spectroscopy. The irradiation of the samples of ?-Fe2O3 was found to be effective in improving its photoelectrochemical response. The film irradiated at a fluence of 1 × 1013 ions cm-2 showed a significantly higher photocurrent density than the unirradiated ?-Fe2O3. This effect is correlated with the transition from the ?-Fe2O3 to the Fe3O4 phase and the reduction in grain size that were observed on irradiation with Ag9+ ions. The measured flatband potential and donor density of the sample were also maximum at a fluence of 1 × 1013 ions cm-2.

Singh, Aadesh P.; Kumari, Saroj; Shrivastav, Rohit; Dass, Sahab; Satsangi, Vibha R.

2009-04-01

292

Mechanisms for ion-irradiation-induced relaxation of stress in mosaic structured Cu thin films  

NASA Astrophysics Data System (ADS)

In this paper, helium (He) ion irradiations with various fluences were performed on sputtered Cu thin films with a mosaic structure to evolve biaxial stress. X-ray diffraction of the ?-2? method was used to determine the residual strains in the thin films by measuring the spacing of the crystallographic planes. The results show the in-plane biaxial tensile stress has been reduced by ion irradiation. A new proposed model is discussed to explain the ion-irradiation-induced stress release in mosaic structured Cu thin films.

Fu, E. G.; Wang, Y. Q.; Nastasi, M.

2012-12-01

293

Characterization and local magnetic modification of ion irradiated GaMnAs  

NASA Astrophysics Data System (ADS)

We study the influence of ion irradiation on magnetic, magneto-transport and structural properties in Ga0.94Mn0.06As films. The carrier concentration is accurately controlled by defects introduced via ion irradiation. Magnetic properties strongly depend on the hole concentration. We present the modification of coercivity, magnetic anisotropy, and magnetotransport properties during such a procedure. By X-ray diffraction and Raman spectra, we exclude the effects from structural changes. Using lithograph made resist mask, one can realize planar local structures with different magnetic properties, indicating the promising future of ion irradiation for spintronics device fabrication.

Li, Lin; Yao, S. D.; Roshchupkina, O.; Prucnal, S.; Akhmadaliev, S.; Campion, R. P.; Rushforth, A. W.; Fassbender, J.; Helm, M.; Gallagher, B. L.; Timm, C.; Schmidt, H.; Zhou, Shengqiang

2011-11-01

294

Circular polarization of ion fluorescence completing the analysis of resonant Xe* 4d(-1)(5/2)6p Auger decay.  

PubMed

The relative contributions of the partial electron waves emitted in the Auger decay of the Xe* 4d(-1)(5/2)6p(J(*)=1) resonance have been determined by fluorescence polarimetry after excitation with circularly polarized synchrotron radiation. The analysis of circularly polarized fluorescence of the photoion leads to an independent determination of the orientation parameters for all states of the Xe II 5p(4)6p multiplet. The present study provides, in combination with data on the angular distribution and spin polarization of the Auger electrons, complete quantum mechanical information on the resonant Auger decay, i.e., branching ratios and relative phases of the Auger decay amplitudes. PMID:12570543

O'Keeffe, P; Aloïse, S; Meyer, M; Grum-Grzhimailo, A N

2003-01-15

295

Fabrication of a TEM sample of ion-irradiated material using focused ion beam microprocessing and low-energy Ar ion milling.  

PubMed

Cross-section-view TEM samples of ion-irradiated material are successfully fabricated using a focused ion beam (FIB) system and low-energy Ar ion milling. Ga ion-induced damages in FIB processing are reduced remarkably by the means of low-energy Ar ion milling. There are optimized ion milling conditions for the reduction and removal of the secondary artifacts such as defects and ripples. Incident angles and accelerated voltages are especially more important factors on the preservation of a clean surface far from secondary defects and surface roughing due to Ga and Ar ion bombardment. PMID:20484144

Jin, Hyung-Ha; Shin, Chansun; Kwon, Junhyun

2010-05-18

296

Effects of energetic heavy ion irradiation on hardness of Al–Mg–Si alloys  

NASA Astrophysics Data System (ADS)

Al–Mg–Si alloys were irradiated with 5.4 MeV Al ions, 7.3 MeV Fe ions, 10 MeV I ions, and 16 MeV Au ions at room temperature and the Vickers microhardness was measured. The hardness of Al–Mg–Si alloys increases with increasing the ion fluence. In a viewpoint of ion fluence, hardness change of the Al alloys is different by the kind of irradiating ions. But, in a viewpoint of the density of elastically deposited energy, the effect of the four kinds of them on hardness is almost the same. This result means that the effect of irradiation on hardness of Al–Mg–Si alloys is dominated by the elastically deposited energy. The microstructure of the ion-irradiated specimens were investigated by means of three-dimensional atom probe (3DAP). The experimental result was compared with the microstructure and the hardness for thermally aged specimens. We also discuss the difference in ion-irradiation induced change in hardness between Al–Mg–Si alloys and Al–Cu–Mg alloys (duralumin).

Ueyama, D.; Saitoh, Y.; Hori, F.; Kaneno, Y.; Nishida, K.; Dohi, K.; Soneda, N.; Semboshi, S.; Iwase, A.

2013-11-01

297

Highly conductive poly(phenylene sulfide) prepared by high-energy ion irradiation  

SciTech Connect

Ion irradiation of poly(phenylene sulfide) (PPS) films with various ions produces highly conductive films. Using 5.6-MeV fluorine ions, the conductivity of irradiated films at a dose of 1 x 10/sup 16/ ions/cm/sup 2/ is comparable to chemically doped films (0.77 S/cm), and higher conductivities should be possible with higher doses. Iodine ions of 50 MeV produced films with similar conductivities at a dose of 1 x 10/sup 14/ ions/cm/sup 2/: the highest conductivity reported for an organic material irradiated by such a low dose. Films irradiated with 0.32-MeV lithium ions did not change their conductivity up to 1 x 10/sup 15/ ions/cm/sup 2/. We attribute the higher conductivities obtained in our iodine irradiated films to the substantially higher electronic energy deposition associated with 50-MeV I ions. The Li-implanted films showed no substantial change in conductivity probably because their energy deposition rates are too low.

Bartko, J.; Hall, B.O.; Schoch K.F. Jr.

1986-02-15

298

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

299

Effects of energetic ion irradiation on the magnetism of Fe–Ni Invar alloy  

NASA Astrophysics Data System (ADS)

The magnetic properties of Fe–Ni Invar alloys are significantly affected by ion irradiation. Au3+ with the energy of 16 MeV irradiation effects on the magnetism of Fe66Ni34 have been reported in this paper. Considering from the temperature variations of AC susceptibility of irradiated Fe66Ni34, Curie temperature of a part of sample increase with increasing incident ion fluence, and the magnetization of irradiated Fe66Ni34 is also increase. The FCC structure of Fe66Ni34 is not changed by ion irradiation; however peaks become broader with increasing ion fluence. It means that lattice fluctuations are generated owing to ion irradiation. However it cannot be considered that lattice fluctuations observed X-ray diffraction measurements are enough to increase the Curie temperature observed in AC susceptibility measurements. Then, we suggest as the considerable origin of increasing TC, atomic mixing effects owing to the ion irradiation. It might change the chemical ordering reported in the diffused scattering, such as Fe–Fe coupling.

Matsushita, M.; Akamatsu, S.; Matsushima, Y.; Iwase, A.

2013-11-01

300

Investigations of structural, dielectric and optical properties on silicon ion irradiated glycine monophosphate single crystals  

NASA Astrophysics Data System (ADS)

The 50 MeV silicon ion irradiation induced modifications on structural, optical and dielectric properties of solution grown glycine monophosphate (GMP) crystals were studied. The high-resolution X-ray diffraction study shows the unaltered value of integrated intensity on irradiation. The dielectric constant as a function of frequency and temperature was studied. UV-visible studies reveal the decrease in bandgap values on irradiation and presence of F-centers. The fluorescence spectrum shows the existence of some energy levels, which remains unaffected after irradiation. The scanning electron micrographs reveal the defects formed on irradiation.

Kanagasekaran, T.; Mythili, P.; Bhagavannarayana, G.; Kanjilal, D.; Gopalakrishnan, R.

2009-08-01

301

Divacancy acceptor levels in ion-irradiated silicon  

NASA Astrophysics Data System (ADS)

High-purity n-type silicon samples have been irradiated with mega-electron-volt ions (1H+, 4He2+, 16O4+, 32S7+, 79Br8+, and 127I10+), and the two divacancy-related acceptor levels ~0.23 and ~0.42 eV below the conduction band (Ec), respectively, have been studied in detail using deep-level transient spectroscopy (DLTS). Depth concentration profiles show identical values for the two levels at shallow depths, while in the region close to the damage peak large deviations from a one-to-one proportionality are found. These deviations increase with ion dose and also hinge strongly on the density of energy deposited into elastic collisions per incoming ion. Evidence for a model of the two levels is presented and, in particular, the model invokes excited states caused by motional averaging and lattice strain associated with damaged regions. The divacancy center is known to exhibit a pronounced Jahn-Teller distortion at low temperatures (<=20 K), and three equivalent electronic distortion directions exist. However, at higher temperatures (>=30 K) reorientation (bond switching) from one distortion direction to another takes place; in a perfect lattice the reorientation rate ultimately becomes so high that the defect does not relax in the distorted configurations, and a motionally averaged state with an effective point-group symmetry of D3d appears. At the temperatures where the DLTS peaks at Ec-0.23 and Ec-0.42 eV are observed, the reorientation time for bond switching is several orders of magnitude smaller than the time for electron emission from the two levels. This implies strongly that the levels originate from the motionally averaged state and not from the distorted state. Consequently, a clear distinction must be made between these DLTS peaks and the charge-state transitions observed in low-temperature studies where the divacancy is frozen in one of the three equivalent distorted configurations. Finally, the association of electronic energy levels with motionally averaged states is expected to apply not only for the divacancy but also for other defects where dynamic effects occur, e.g., the monovacancy and the E center.

Svensson, B. G.; Mohadjeri, B.; Hallén, A.; Svensson, J. H.; Corbett, J. W.

1991-01-01

302

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

303

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

NASA Astrophysics Data System (ADS)

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 8.4×1013 ions/cm2 is required to induce a large improvement in the EFE properties of the UNCD films. Postannealing the Au-ion irradiated films at 1000 °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; Sundaravel, Balakrishnan; Amirthapandian, Sankarakumar; Lin, I.-Nan

2010-12-01

304

The effect of composition on the formation of light-emitting Si nanostructures in SiO{sub x} layers on irradiation with swift heavy ions  

SciTech Connect

The SiO{sub x} layers different in composition (0 < x < 2) are irradiated with Xe ions with the energy 167 MeV and the dose 10{sup 14} cm{sup -2} to stimulate the formation of light-emitting Si nanostructures. The irradiation gives rise to a photoluminescence band with the parameters dependent on x. As the Si content is increased, the photoluminescence is first enhanced, with the peak remaining arranged near the wavelength {lambda} Almost-Equal-To 600 nm, and then the peak shifts to {lambda} Almost-Equal-To 800 nm. It is concluded that the emission sources are quantum-confined nanoprecipitates formed by disproportionation of SiO{sub x} in ion tracks due to profound ionization losses. Changes in the photoluminescence spectrum with increasing x are attributed firstly to the increase in the probability of formation of nanoprecipitates and then to the increase in their dimensions; the latter effect is accompanied with a shift of the emission band to longer wavelengths. The subsequent quenching of photoluminescence is interpreted as a result of the removal of quantum confinement in nanoprecipitates and their coagulation.

Kachurin, G. A., E-mail: kachurin@isp.nsc.ru; Cherkova, S. G.; Marin, D. V.; Kesler, V. G. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Skuratov, V. A. [Joint Institute for Nuclear Research (Russian Federation); Cherkov, A. G. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

2011-03-15

305

Primordial Terrestrial Xe from the Viewpoint of CFF-Xe  

NASA Astrophysics Data System (ADS)

We have already reported [7, 23] on the non-linear isotope mass-fractionation of fission Xe by migration of the precursors I, Te, Sn, and Sb and simultaneous fission of heavy nuclei. Xe with anomalous isotopic pattern was found in a number of meteorites and terrestrial materials and was named CFF-Xe (Chemically Fractionated Fission Xe). It is characterized by an up eightfold ^132Xe and ^131Xe excesses coupled with smaller ^134Xe and ^129Xe excesses. The present work is aimed to estimate the role of CFF-Xe in the terrestrial lithosphere and specifically deals with the problem of the isotopic composition of primordial terrestrial Xe. Due to variations of the migration conditions the isotopic structure of CFF-Xe is not well established and is even not reproducible in the same rock [2]. Nevertheless, we have tried to estimate the composition of CFF-Xe by investigating all available isotopic data of Xe of presumable mantle origin. This is Xe in MORB [29, 1, 12] and ocean island glasses [1, 28], in diamonds [17], in volcanic rocks [29, 8, 9, 21], in volcanic glasses from pillow basalts [16, 6], continental igneous rocks [1, 24, 10, 22], carbonatites and granitoids [1] as well as Xe in natural gases [3, 24, 11, 4, 15]. All data are plotted Fig. 1 where we also suggest end members of the observed scattering. Optimized slopes of CFF-lines are shown as well as the position of the initial points which we regard as primordial terrestrial Xe (Xe0). The isotopic composition of CFF-Xe and Xe0 are given in Tab. 1. The abundances of ^124Xe and ^126Xe in mantle derived samples are very uncertain, but since ^128Xe/^130Xe in Xea and Xe0 is very similar we propose the same ^124Xe/^130Xe and ^126Xe/^130Xe ratios for both Xea and Xe0. If so, AVCC-Xe is simply Xe0 with an admixture of L-Xe, and atmospheric xenon Xea consists of Xe0, CFF-Xe and a small amount of fission Xe (92.5%Xe0 + 5.3%CFF-Xe + 2.2%XeF). Thus, a number of old problems in xenology are removed. The hypothetic components U-Xe or atmosphere-like Xe are not required anymore. Instead, experimentally identified Xe0 can be regarded as primordial terrestrial Xe with an isotopic composition close to AVCC-Xe. Isotopic mass-fractionation is not needed to be involved. Concerning ^129Xe in the mantle, it seems to be part of CFF-Xe rather than the product of primordial 129I decay. This interpretation is supported by the observation of 129I excesses near uranium deposits that provides an additional argument in favor the CFF-Xe hypothesis [5, 14]. This work is supported by INTAS # 94-2397. References: [1] Allegre C. J. et al. (1983) Nature, 303, 762-766. [2] Azuma Sh. et al. (1993) EPSL, 114, 341-352. [3] Boulos M. S. et al. (1971) Science, 174, 1334-1336. [4] Caffee M. W. et al. (1988) AGU Meeting in San Francisco, reprint. [5] Fabrika-Martin J. et al. (1989) GCA, 53, 1817-1823.[6] Hiyagon H. et al. (1992) GCA, 56, 1301-1316. [7] Jessberger E. K. et al. (1992) LPS XXIII, 615-616. [8] Kaneoka I. et al. (1978) EPSL, 39, 382-386. [9] Kaneoka I. et al. (1983) EPSL, 66, 427-437. [10] Levsky L. K. (1993) personal communication. [11] Lin W. J. and Manuel O. K. (1987) Geochem. J., 2, 197-207. [12] Marty B. (1989) EPSL, 94, 45-56. [13] Meshik A. P. (1988) Ph.D. thesis , Vernadsky Institute, Moscow, 211 pp., in Russian. [14] Michelot J. L. et al. (1989) GCA, 53, 1803-1815. [15] Murty S. V. S. (1992) Chem. Geol., 94, 229-240. [16] Ozima M. and Podosek F. A. (1983) Noble Gas Geochemistry, Cambridge Univ., 367 pp. [17] Ozima M. and Zashu S. (1991) EPSL, 105, 13-27. [18] Ozima M. et al. (1983) EPSL, 62, 24-40. [19] Pepin R. O. (1993) preprint. [20] Phinney D. et al. (1978) JGR, 83, 2313-2319. [21] Poreda J. and Farley K. A. (1992) EPSL, 113, 129-144. [22] Schafer K. et al. (1993) Jahresbericht, 244-245, MPI fur Kernphysik, Heidelberg. [23] Shukolyukov Yu. A. et al. (1994) GCA, 58, 3075-3092. [24] Smith S. P. (1984) GCA, 48, 1033-1041. [25] Smith S. P.and Reinolds J. H. (1981) EPSL, 54, 236-238. [26] Staudacher Th. (1987) Nature, 325, 605-609. [27] Staudacher Th. and Allegre C. J. (1982) EPSL, 60, 389-406.

Meshik, A. P.; Shukolyukov, Yu. A.; Jessberger, E. K.

1995-09-01

306

Shear banding mechanism of plastic deformation in LiF irradiated with swift heavy ions  

NASA Astrophysics Data System (ADS)

The effect of ion irradiation on the behavior of plastic deformation at micro- and nanoindentation on (001) face of LiF has been investigated. The irradiation was performed using heavy ions (U, Au, Ti and S) with energy in the range from 3 MeV to 2 GeV at fluences up to 5x1013 ions/cm2. In non-irradiated LiF, the indentation produces dislocation gliding on the {110} planes along the <100> and <110> directions. At high fluence irradiation, the resource of the dislocation slip along the preferable directions becomes exhausted due to immobilization of dislocations by radiation defects and their aggregates. The present study demonstrates the change of the mechanism of plastic deformation from homogenous dislocation slip to localized shear banding in samples irradiated to high fluences. The factors facilitating of the localization of deformation have been analyzed.

Maniks, J.; Zabels, R.; Manika, I.

2012-08-01

307

Grain growth and size distribution in ion-irradiated chemical vapor deposited amorphous silicon  

SciTech Connect

The amorphous to polycrystal transition in chemical vapor deposited (CVD) amorphous silicon has been studied at 450 /degree/C under Kr ion beam irradiation. The average grain size increases linearly with the ion dose, and the grain size distribution is very narrow compared to thermally grown grains. These results are consistent with the presence of crystal seeds in CVD material. All these seeds can grow simultaneously under ion beam irradiation. For layers completely preamorphized by Ge/sup +/ implantation, no ion beam induced nucleation is observed.

Spinella, C.; Lombardo, S.; Campisano, S. U.

1989-07-10

308

Electron spin resonance and photoluminescence in pyrolytic silicon nitride films irradiated with argon and molecular ions  

SciTech Connect

The photoluminescence and electron spin resonance phenomena are studied at room temperature for pyrolytic silicon nitride films irradiated with argon ions or molecular nitrogen ions and annealed at temperatures in the range 500-1100{sup o}C. The absorption spectrum suggests that the broad photoluminescence band at 400-600 nm is due to electron transitions between the band tails. The low-dose irradiation with argon ions slightly reduces the photoluminescence intensity, whereas the high-dose irradiation followed by annealing at 800-900{sup o}C can induce a more than twofold increase in the intensity. At the same time, irradiation with nitrogen ions profoundly suppresses the integrated photoluminescence intensity that decreases by more than an order of magnitude. A correlation between the changes in the photoluminescence intensity and the amplitude of the ESR spectra on annealing of the silicon nitride films is observed.

Demidov, E. S.; Dobychin, N. A.; Karzanov, V. V.; Marychev, M. O.; Sdobnyakov, V. V. [Lobachevskii State University (Russian Federation)], E-mail: Sdobnyakov@phys.unn.ru

2009-07-15

309

Adhesive failure of gold films on tantalum pentoxide produced by MeV ion irradiation  

NASA Astrophysics Data System (ADS)

Here we report work on the MeV irradiation adhesion modification of gold films on deposited tantalum pentoxide. For this system irradiation produces bubbling of the film at comparatively low doses, which in some cases leads directly to failure of the gold film. This is in contrast to the results of irradiation of gold on native or thermally grown tantalum oxide samples where enhanced adhesion is observed. Irradiation by 5 × 1013 ions/cm2 of 20 MeV 35Cl and 1 × 1013ions/cm2 of 40 MeV 81Br were observed to release 100 and 5000 H atoms per ion, respectively. The nature of the bonding of the hydrogen and the details of the ion-induced release are unknown, although electronic stopping is thought to be the driving force rather than bulk heating effects.

Sugden, S.; Sofield, C. J.; Bridwell, L. B.

1990-03-01

310

Structural, Dielectric and Temperature Dependent Raman Spectroscopic Studies on Swift Heavy Ion Irradiated Tgs Crystals  

NASA Astrophysics Data System (ADS)

Polar cleavage surface of tri-glycine sulphate (TGS) of important room temperature ferroelectric crystal irradiated with 100 MeV oxygen ion beam are characterized to understand the effect of irradiation on structural, dielectric and vibrational modes of the crystal. X-ray diffraction results show lattice parameters a and b in monoclinic unit cell decrease with increasing fluence, whereas parameter `c' increases. However, the irradiated crystal remains in monoclinic phase. Dielectric anomaly peak value associated with paraelectric--ferroelectric phase transition gets reduce with irradiation and Tc shift towards lower temperature. A comparison of the Raman spectra of unirradiated crystal with those irradiated in both paraelectric and ferroelectric phase reveals the molecular ion getting distorted as a result of irradiation.

Bajpai, P. K.; Shah, Deepak; Kumar, Ravi; Kumar, Ashok; Katiyar, R. S.

2011-11-01

311

Effect of heavy-ion irradiation on transport properties of YBa2Cu3Ox films  

Microsoft Academic Search

We have investigated the effect of heavy-ion irradiation on the transport properties of YBa2Cu3Ox thin films. Parallel columnar defects to the c axis and crossed columnar defects were introduced into films by heavy-ion irradiation with dose equivalent to 1 or 2 T vortex density. The electrical transport properties including resistivity, critical current density, and the Hall resistivity were measured as

Dong Ho Kim; Seong Yup Shim; Jong Hyeog Park; Young Hwan Kim; Chang Hoon Kim; Jin Wook Jang; Taek Sang Hahn; Sang Sam Choi; Jeffrey D. Hettinger; David G. Steel; Kenneth E. Gray

1997-01-01

312

Swift heavy ion irradiation induced damage creation in nanocrystalline Li–Mg ferrite thin films  

Microsoft Academic Search

Nanocrystalline Li0.25Mg0.5Mn0.1Fe2.15O4 ferrite thin films, prepared by R.F. magnetron sputtering technique, are irradiated with 190 MeV Au14+ ions. The significant behavioural changes in magnetic and electrical properties of thin films after swift heavy ion irradiation confirm the formation of stable defects. A transformation from ferrimagnetic to superparamagnetic behaviour is observed from CEMS (conversion electron Mössbauer spectroscopy) with increase in fluence

Sanjukta Ghosh; Ajay Gupta; Pushan Ayyub; Nitendar Kumar; S. A. Khan; D. Banerjee; R. Bhattacharya

2004-01-01

313

In situ 1\\/ f noise studies on swift heavy ion irradiated p-type silicon  

Microsoft Academic Search

We have used in situ resistance and conduction noise measurements to study the influence of swift heavy ion (SHI) irradiation induced defects on the conduction process in p-Si. The irradiation was performed at room temperature and 77 K with 100 MeV 107Ag ions. We have observed that the resistance does not change much at low fluences and shows a sharp

S. K Arora; Rajendra Singh; Ravi Kumar; D. Kanjilal; G. K Mehta

1999-01-01

314

Swift heavy ion irradiation-induced phase transformation in oxide materials  

Microsoft Academic Search

The present study briefly reviews the effect of ion irradiation in inducing structural transformation in oxide materials. The effect of ion irradiation on simple systems such as Y2O3, CuO, ZrO2, HfO2 and TiO2 and a few members of the high Tc cuprate superconductor family are examined. Some of the phase transformations induced are shown to be uniquely possible by swift

N. C. Mishra

2011-01-01

315

Severe creep of a crystalline metallic layer induced by swift-heavy-ion irradiation  

Microsoft Academic Search

The aim of the experiments presented in this paper was to study the mechanisms leading to the atomic transport process (plastic deformation) induced in amorphous solids by GeV heavy-ion irradiation. Ni3B\\/Au\\/Ni3B sandwiches, composed of a crystalline Au layer of various thicknesses and of two amorphous Ni3B layers, were irradiated at liquid nitrogen temperature with 500-MeV iodine ions. The Rutherford backscattering

F. Garrido; A. Benyagoub; A. Chamberod; J.-C. Dran; A. Dunlop; S. Klaumünzer; L. Thomé

1995-01-01

316

Development of an ion microbeam system for irradiating single plant cell[s  

Microsoft Academic Search

An ion microbeam system for irradiating single plant cells was developed to analyze exact biological effects of ion beams. Tobacco BY-2 protoplasts were used as a model of single plant cells. Protoplasts were cultured in thin agarose medium on a specially designed irradiation-vessel, which has a CR-39 nuclear track detector (a 100-?m thick sheet). The colony formation rate of unirradiated

Yuichiro Yokota; Tomoo Funayama; Yasuhiko Kobayashi; Tetsuya Sakashita; Seiichi Wada; Yoshihiro Hase; Naoya Shikazono; Atsushi Tanaka; Masayoshi Inoue

2003-01-01

317

Elongation of gold nanoparticles in silica glass by irradiation with swift heavy ions  

SciTech Connect

We examined the mechanism whereby nanoparticles of gold embedded in silica become elongated and oriented parallel to each other on ion irradiation. Elongation occurred for gold particles with radii smaller than 25 nm. The process was simulated by using a thermal spike model. For small-radius nanoparticles, ion irradiation raises the temperature above the melting points of both gold and silica, whereas for larger nanoparticles neither the gold nanoparticle nor the surrounding silica matrix is melted.

Awazu, Koichi; Wang Xiaomin; Fujimaki, Makoto; Tominaga, Junji; Aiba, Hirohiko; Ohki, Yoshimichi; Komatsubara, Tetsuro [Center for Applied Near-field Optics Research, AIST, 1-1-1 Higashi Tsukuba 305-8562 (Japan); Department of Electrical Engineering and Bioscience, Waseda University, Shinjuku, Tokyo 169-8555 (Japan); Tandem Accelerator Complex, University of Tsukuba, Tsukuba 305-8577 (Japan)

2008-08-01

318

Thermal annealing of vacancy and interstitial loops in ion irradiated copper  

SciTech Connect

X-ray diffuse scattering has been used to study the thermal annealing of vacancy and interstitial loops in Ni-ion irradiated copper. The diffuse scattering formalism is reviewed and diffuse scattering measurements are reported on liquid-He temperature Ni-ion irradiated copper after annealing to 40, 275, and 300/sup 0/C. Size distributions are presented for vacancy and interstitial loops after each anneal and the thermal-induced changes are discussed in terms of loop dissolution and coalescence.

Larson, B.C.; Noggle, T.S.; Barhorst, J.F.

1985-01-01

319

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

NASA Astrophysics Data System (ADS)

The surface of L-leucine films irradiated with an Ar5000 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; Ibuki, Sachi; Ichiki, Kazuya; Ninomiya, Satoshi; Seki, Toshio; Aoki, Takaaki; Matsuo, Jiro

2011-01-01

320

Swift heavy ion irradiation effects in Pt\\/C and Ni\\/C multilayers  

Microsoft Academic Search

Irradiation effects of 100 MeV Ag ion irradiation on Ni\\/C and Pt\\/C multilayers have been studied using X-ray reflectivity measurements. Modifications are observed in both the multilayers at (dE\\/dx)e values much below the threshold values for Ni and Pt. This effect is attributed to the discontinuous nature of the metal layers. In both the multilayers interfacial roughness increases with irradiation

Ajay Gupta; Suneel Pandita; D. K Avasthi; G. S Lodha; R. V. Nandedkar

1998-01-01

321

Grain growth and crack formation in NiO thin films by swift heavy ion irradiation  

Microsoft Academic Search

NiO thin films grown on Si(100) substrates by electron beam evaporation and sintered at 700°C, were irradiated by 120MeV Au9+ ions. Though irradiation is known to induce lattice disorder and suppression of crystallinity, we observe grain growth at some fluences of irradiation. Associated with the growth of grains, the films develop cracks at a fluence of 3×1012ionscm?2. The width of

P. Mallick; R. Biswal; Chandana Rath; D. C. Agarwal; A. Tripathi; D. K. Avasthi; D. Kanjilal; P. V. Satyam; N. C. Mishra

2010-01-01

322

Effects of ion beam irradiation on the regeneration and morphology of Ficus thunbergii Maxim  

Microsoft Academic Search

Shoot explants cut from aseptically grown Ficus thunbergii plants were irradiated with 12C5? , 12C6? and 4He2? ion beams of 10 to 200 Gray (Gy). After irradiation, the explants were allowed to regenerate. The regeneration frequency (RF), or percent explants bearing regenerated shoots to the total number of explants irradiated, decreased in a dose- dependent manner. Morphological changes in leaves

Misa Takahashi; Sueli Kohama; Komei Kondo; Makoto Hakata; Yoshihiro Hase; Naoya Shikazono; Atsushi Tanaka; Hiromichi Morikawa

323

Application of ion beam irradiated ePTFE to repair small vessel injuries  

NASA Astrophysics Data System (ADS)

In surgery, bleeding from small injured vessels often requires prompt hemostasis without occlusion. This study evaluated the usefulness of 0.06 mm thick ion beam irradiated ePTFE sheets to repair small holes in vessels. Both surfaces of ePTFE sheets were irradiated with a 150 keV-Ar+ beam with fluences of 5 × 1014 ions/cm2. A small hole up to 2 mm in diameter was created in the common carotid artery of a rabbit. The defect was wrapped with an ion beam irradiated or non-irradiated ePTFE sheet. Fibrin glue was used to fix the ePTFE sheets to the common carotid artery. Hemostasis was instantly obtained with ion beam irradiated ePTFE but was rather difficult when using a non-irradiated ePTFE sheet. Three weeks after implantation, no occlusion was observed. Histological examination showed that the ePTFE sheets functioned as a scaffold for vessel wall regeneration. Thin ion beam irradiated ePTFE would be useful in vascular surgery.

Takahashi, N.; Suzuki, Y.; Ujiie, H.; Hori, T.; Iwaki, M.; Yamada, T.

2007-04-01

324

Investigation of damage in GaAs single crystals after irradiation by Ne+ ions  

Microsoft Academic Search

According to established ideas, the irradiation by energetic ions induces a significant number of point defects (1). This process is multi-stage and includes generation of radiation induced vacancies and interstitial atoms (Frenkel pairs). The subsequent motion of these defects towards the surface and internal interfaces, as well as their interaction with each other, and with other imperfections of an irradiated

A. Zolotaryov; K. Shcherbachev; F. Wu; R. L. Johnson

325

CHANGES IN THE PROPERTIES OF ION-EXCHANGE RESINS PRODUCED BY IRRADIATION WITH IONIZING RADIATION  

Microsoft Academic Search

Changes in the exchange capacity, activity index, swelling in water, and ; in the solubllity of ion exchange resins (IER) produced by exposure to x rays ; were investigated. The changes produced when dry and waterswollen IER are ; irradiated with x rays are quite different. Direct irradiation effects were ; established as well as an indirect hydroxylation effect which

O. Costachel; Gh. Furnica; St. Grigorescu

1958-01-01

326

Atomic fingers, bridges and slingshots: formation of exotic surface structures during ion irradiation of heavy metals  

Microsoft Academic Search

Recent experiments on ion irradiation of heavy metals such as gold and silver have shown that very unusual surface configurations can be produced by the irradiation. Typically, the surface damage has the shape of a crater, similar to those produced by meteorite impacts. The crater shapes are, however, often highly asymmetric and can show extended adatom ridges extending far from

K. Nordlund; J. Tarus; J. Keinonen; S. E. Donnelly; R. C. Birtcher

2003-01-01

327

Nanocrystalline phase formation and surface smoothing of titanium by intense pulsed ion beam irradiations  

Microsoft Academic Search

Summary form only given. Metal surface characterization by irradiation of an intense pulsed ion beam (IPIB) has been studied experimentally. The IPIB irradiation of metals leads to rapid heating of the surface which is immediately followed by rapid cooling and resolidification, resulting in metal surface modification. Attention is focused on the formation of nanocrystalline phase and the reduction of machining

Y. Hashimoto; M. Yatsuzuka; T. Yamasaki; H. Uchida

1996-01-01

328

Conduction mechanisms in ion-irradiated InGaAs layers  

SciTech Connect

The electrical and optical properties of H{sup +}- and Au{sup +}-irradiated InGaAs layers were studied using Hall-effect, van der Pauw, and relaxation-time measurements. Comparing the different results allows us to obtain information on the nature of the defects created by these two irradiations. Proton irradiation introduces donor-acceptor paired defects. Gold-ion irradiation creates neutral defect clusters and ionized point defects. The carrier mobilities in all of the irradiated materials are degraded, decreasing with increasing irradiation dose. A scattering model taking into account the paired defects is developed and the mobility evolution calculated from this model agrees with the experimental data of both annealed and unannealed samples. The photocurrent spectra reveal a metallic conduction in the band gap in the case of light-ion irradiation, while such type of conduction does not appear for heavy-ion irradiation. This metallic conduction is a consequence of band tailing induced by shallow defects and vanishes when the material is annealed at 400 deg. C. The proton irradiation-induced defects appear to be related to the EL-2-like defects.

Joulaud, L.; Mangeney, J.; Chimot, N.; Crozat, P.; Fishman, G.; Bourgoin, J.C. [Institut d'Electronique Fondamentale, UMR Centre National de la Recherche Scientifique (CNRS) 8622, Universite Paris Sud, bat. 220, 91405 Orsay Cedex (France); Gesec Research and Development, 68 Avenue de la Foret, 77210 Avon (France)

2005-03-15

329

Ion Beam Analysis of Irradiation Effects in 6H-SiC  

SciTech Connect

Irradiation in 6H-SiC single crystal wafers has been performed at temperatures ranging from 150 to 550 K using 2.0 MeV Au or at 300 K using 50 keV He ions. Additional irradiation for the He-irradiated specimen was carried out near room temperature using 50 MeV I10 ions to {approx}0.1 ions/nm. In-situ isothermal annealing for 6H-SiC irradiated at 500 K to 2.0 Au/nm was also conducted up to 90 min at the irradiation temperature. The lattice disorder in the irradiated samples has been determined using either 2.0 MeV He or 0.94 MeV D channeling analysis along the <0001> axis. Results show that there is a substantial diffusion of the Si defects into a greater depth during the Au irradiation at 500 and 550 K. Complete amorphization at 550 K does not occur up to a maximum fluence of 15 Au/nm in this study. Significant thermal recovery of the Si defects produced at 150 K was not observed during the subsequent thermal annealing at 500 K. Following the I10 irradiation in the He-irradiated specimen near room temperature, remarkable recrystallization at the amorphous-crystalline interfaces around the damage profile is observed.

Jiang, Weilin; Weber, William J.; Zhang, Yanwen; Thevuthasan, Suntharampillai; Shutthanandan, V

2003-05-16

330

n-Selective Single Capture Following Xe{sup 18+} And Xe{sup 54+} Impact On Na(3s) And Na*(3p)  

SciTech Connect

State selective single charge exchange n-level cross sections are calculated for collisions of Xe18+ and Xe54+ ions with Na(3s) and Na*(3p) over the energy range of 0.1 to 10.0 keV/amu. The CTMC method is used which includes all two-body interactions. Experimental state-selective cross sections and their corresponding transverse momentum spectra for Xe18+ are found to be in reasonable accord with the calculations.

Otranto, S. [CONICET and Dto. de Fisica, Universidad Nacional del Sur, 8000 Bahia Blanca (Argentina); Olson, R. E. [Physics Department, Missouri University of Science and Technology, Rolla, MO 65401 (United States); Hasan, V. G.; Hoekstra, R. [KVI-Atomic and Molecular Physics, University of Groeningen (Netherlands)

2011-06-01

331

Fabrication and Characterization of APT Specimens from High Dose Heavy Ion Irradiated Materials  

SciTech Connect

The next generations of advanced energy systems will require materials that can withstand high doses of irradiation at elevated temperatures. Therefore, a methodology has been developed for the fabrication of high-dose ion-irradiated atom probe tomography specimens at a specific dose with the use of a focused ion beam milling system. The method also enables the precise ion dose of the atom probe tomography specimen to be estimated from the local concentration of the implanted ions. The method has been successfully applied to the characterization of the distribution of nanoclusters in a radiation-tolerant 14YWT nanostructured ferritic steel under ion irradiation to doses up to 400 displacements per atom.

Miller, Michael K [ORNL; Zhang, Yanwen [Pacific Northwest National Laboratory (PNNL)

2011-01-01

332

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

333

Modeling of the LIFE minichamber Xe theta pinch experiment  

Microsoft Academic Search

The LIFE minichamber experiment is being designed to investigate cooling of the Xe buffer gas protecting the LIFE chamber wall. A magnetically driven theta pinch configuration will be used to inductively heat a few-cm long cylinder of Xe at ion density 2e16\\/cc to several eV. Thomson scattering will be used to determine the electron temperature and ionization state of the

Jave Kane; Mark Rhodes; Gwendolen Loosmore; Jeffery Latkowski; Joseph Koning; Mehul Patel; George Zimmerman; James Demuth; Gregory Moses

2010-01-01

334

Modeling of the LIFE minichamber Xe theta pinch experiment  

Microsoft Academic Search

The LIFE minichamber experiment will investigate cooling of the strongly radiating Xe buffer gas protecting the LIFE chamber wall. A theta pinch will inductively heat a few cc of Xe at ion density 2e16\\/cc to several eV. Thomson scattering will be used to determine electron temperature and ionization state. Modeled is being done using the magnetohydrodynamic code HYDRA with an

J. O. Kane; M. A. Rhodes; G. A. Loosmore; J. F. Latkowski; J. M. Koning; M. V. Patel; H. A. Scott; G. B. Zimmerman; J. A. Demuth; G. A. Moses

2011-01-01

335

Highly charged heavy ion generation by pulsed laser irradiation  

Microsoft Academic Search

At the Laboratorio Nazionale del Sud of the National Institute of Nuclear Physics (INFN-LNS) of Catania, different ion sources of multi-charged ions are available, including electron cyclotron resonance ion sources (ECRIS) and a laser ion source, based on a high energy infra-red pulsed laser working in single shot or pulsed mode with repetition rate of 30 Hz. A hybrid ion

S. Gammino; L. Torrisi; G. Ciavola; L. Andò; J. Wolowski; L. Laska; J. Krasa; A. Picciotto

2003-01-01

336

Kr-86 ion-beam irradiation of hydrated DNA: free radical and unaltered base yields.  

PubMed

This work reports an ESR and product analysis investigation of Kr-86 ion-beam irradiation of hydrated DNA at 77 K. The irradiation results in the formation and trapping of both base radicals and sugar phosphate radicals (DNA backbone radicals). The absolute yields (G, ?mol/J) of the base radicals are smaller than the yields found in similarly prepared ?-irradiated DNA samples, and the relative yields of backbone radicals relative to base radicals are much higher than that found in ?-irradiated samples. From these results, we have elaborated our radiation chemical model of the track structure for ion-beam irradiated DNA as it applies to krypton ion-beams. The base radicals, which are trapped as ion radicals or reversibly protonated or deprotonated ion radicals, are formed almost entirely in the track penumbra, a region in which radiation chemical effects are similar to those found in ?-irradiated samples. By comparing the yields of base radicals in ion-beam samples to the yields of the same radicals in ?-irradiated samples, the partition of energy between the low-LET region (penumbra) and the core is experimentally determined. The neutral sugar and other backbone radicals, which are not as susceptible to recombination as are ion radicals, are formed largely in the track core. The backbone radicals show a linear dose response up to very high doses. Unaltered base release yields in Kr-86 irradiated hydrated DNA are equal to sugar radical yields within experimental error limits, consistent with radiation-chemical processes in which all base release originates with sugar radicals. Two phosphorus-centered radicals from fragmentation of the DNA backbone are found in low yields. PMID:23106211

Becker, David; Adhikary, Amitava; Tetteh, Smedley T; Bull, Arthur W; Sevilla, Michael D

2012-10-29

337

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

338

Irradiation effects of swift heavy ions in actinide oxides and actinide nitrides: Structure and optical properties  

NASA Astrophysics Data System (ADS)

Actinide oxides have been used as nuclear fuels in the majority of power reactors working in the world and actinide nitrides are under investigation for the fuels of the future fast neutron fission reactors developed in Forum Generation IV. Radiation damage in actinide oxides UO2, (U0.92Ce0.08)O2, and actinide nitride UN has been characterized after irradiation with swift heavy ions. Fluences up to 3 × 1013 ions/cm2 of heavy ions (Kr 740 Mev, Cd 1 GeV) available at the CIRIL/GANIL facility were used to simulate irradiation in reactors by fission products and by neutrons. The macroscopic effects of irradiation remains very weak compared with those seen in other ceramic oxides irradiated in the same conditions: practically no swelling can be measured and no change in colour can be observed on the irradiated part of a polished face of sintered disks. The point defects in irradiated actinide compounds have been characterized by optical absorption spectroscopy in the UV Vis NIR wavelength range. The absorption spectra before and after irradiation are compared, and unexpected stability of optical properties during irradiation is shown. This result confirms the low rate of formation of point defects in actinide oxides and actinide nitrides under irradiation. Actinide oxides and nitrides studied are >40% ionic, and oxidation state of the actinides seems to be stable during irradiation. The small amount of point defects produced by radiation (<1016 cm-2) has been identified from differences between the absorption spectrum before irradiation and the one after irradiation: point defects in oxygen or nitrogen lattices can be observed respectively in oxides and nitrides (F centres), and small amounts of U5+ would be present in all compounds.

Beauvy, Michel; Dalmasso, Chrystelle; Iacconi, Philibert

2006-09-01

339

Observation of DNA damage of human hepatoma cells irradiated by heavy ions using comet assay  

Microsoft Academic Search

AIM: Now many countries have developed cancer therapy with heavy ions, especially in GSI (Gesellschaft für Schwerionenforschung mbH, Darmstadt, Germany), remarkable results have obtained, but due to the complexity of particle track structure, the basic theory still needs further researching. In this paper, the genotoxic effects of heavy ions irradiation on SMMC-7721 cells were measured using the single cell gel

Li-Mei Qiu; Wen-Jian Li; Xin-Yue Pang; Qing-Xiang Gao; Yan Feng; Li-Bin Zhou; Gao-Hua Zhang

2003-01-01

340

Anomalous charge loss from floating-gate memory cells due to heavy ions irradiation  

Microsoft Academic Search

We are presenting new data on the charge loss in large floating gate (FG) memory arrays subjected to heavy ion irradiation. Existing models for charge loss from charged FG and generation-recombination after a heavy ion strike are insufficient to justify (or in contrast with) our experimental results. In particular, the charge loss is by far larger than predicted by existing

G. Cellere; A. Paccagnella; L. Larcher; A. Chimenton; J. Wyss; A. Candelori; A. Modelli

2002-01-01

341

High energy ion beam irradiation on titanium substrate in a pulsed plasma device operating with methane  

Microsoft Academic Search

We report the investigation of high energy ion beam irradiation on titanium (Ti) substrates at room temperature using a low energy plasma focus (PF) device operating in methane gas. The surface modifications induced by the ion beam using two different anode materials, graphite and copper, are characterized using standard surface science diagnostic tools, such as x-ray diffraction, scanning electron microscopy,

H. Bhuyan; M. Favre; E. Valderrama; A. Henriquez; G. Vogel; H. Chuaqui; E. Wyndham; A. Cabrera; E. Ramos-Moore; P. A. Núñez; H. Kelly; D. Grondona; S. Goyanes

2009-01-01

342

Quantification of electron-ion recombination in an electron-beam-irradiated gas capacitor  

Microsoft Academic Search

A model is developed for electron-ion recombination in a gas capacitor in which the cathode is irradiated simultaneously by an electron beam and a defocused flux of soft-landing ions, under conditions such as encountered in variable pressure scanning electron microscopes (SEMs). The model describes the dependence of the secondary electron (SE) emission current (injected into the gas from the cathode)

M Toth; D R Daniels; B L Thiel; A M Donald

2002-01-01

343

Vibrational Spectroscopy in Ion-Irradiated Carbon-Based Thin Films  

NASA Astrophysics Data System (ADS)

In this work we present and discuss some selected experiments on ion-irradiated carbon-based thin films. Vibrational spectroscopy is used to investigate the materials structure and to explore the mechanisms of ion beam-induced modifications in many carbon solids such as crystalline carbon and carbon alloys, hydrocarbon molecules and exotic carbon species.

Compagnini, Giuseppe; Puglisi, Orazio; Baratta, Giuseppe A.; Strazzulla, Giovanni

344

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

345

Damage and Microstructure Evolution in GaN under Au Ion Irradiation  

SciTech Connect

Damage and microstructure evolution in gallium nitride (GaN) under Au+ ion irradiation has been investigated using complementary electron microscopy, secondary ion mass spectrometry and ion beam analysis techniques. Epitaxially-grown GaN layers (2-um-thick) have been irradiated by 2.0 MeV Au ions to 1.0 × 1015 and 1.4 × 1015 cm-2 at 155 K and 7.3 × 1015 cm-2 at 200 K. The irradiation-induced damage has been analyzed by Rutherford backscattering spectroscopy in a channeling direction (RBS/C). For a better determination of ion-induced disorder profile, an iterative procedure and a Monte Carlo code (McChasy) are combined to analyze the ion channeling spectra. With increasing irradiation dose, separated amorphous layers develop from the sample surface and near the damage peak region. Formation of large nitrogen bubbles with sizes up to 70 nm is observed in the buried amorphous layer, while the surface layer contains small bubbles with diameter of a few nanometers due to significant nitrogen loss from the surface. Volume expansion from 3% to 25% in the irradiated region is suggested by cross sectional transmission electron microscope and RBS/C measurement. The anomalous shape of the Au distributions under three irradiations indicates out-diffusion of Au toward sample surface. The results from the complementary techniques suggest that nitrogen is retained in the damaged GaN where the crystallinity is preserved. Once the amorphous state is reached in the surface region, GaN starts to decompose and nitrogen escapes from the surface. Furthermore, experimental results show considerable errors in both disorder profile and ion range predicted by the Stopping and Range of Ions in Matter code, indicating a significant overestimation of electronic stopping powers of Au ions in GaN.

Zhang, Yanwen; Ishimaru, Manabu; Jagielski, Jacek; Zhang, Weiming; Zhu, Zihua; Saraf, Laxmikant V.; Jiang, Weilin; Thome, Lionel; Weber, William J.

2010-02-11

346

Opto-chemical response of CR-39 and polystyrene to swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

The samples of CR-39 and polystyrene (PS) polymers have been irradiated with 64Cu9+ (120 MeV) and 12C5+ (70 MeV) ion beams having fluence ranging from 1 × 1011 to 1 × 1013 ions/cm-2. UV spectra of irradiated samples reveal that the optical band gap decreases from 5.50 to 2.75 eV in CR-39 and from 4.36 to 1.73 eV in PS. The correlation between optical band gap and the number of carbon atoms in a cluster with modified Tauc’s equation has been discussed in case of CR-39. FTIR spectra reveal that there is the formation of hydroxyl, alkene, alkyne and carboxylic groups in the Cu-ion irradiated PS. In CR-39, changes in the intensity of the bands on irradiation relative to pristine samples without appearance of any new band have been observed and discussed.

Singh, Lakhwant; Singh Samra, Kawaljeet; Singh, Ravinder

2007-02-01

347

Structural and magnetic study of swift heavy ion irradiated W/Fe multilayer structure  

NASA Astrophysics Data System (ADS)

The present study reports the effect of swift heavy ion irradiation on structural and magnetic properties of sputtered W/Fe multilayer structure (MLS) having bilayer compositions of [W(10 Å)/Fe(20 Å)]10BL. The MLS is irradiated by 120 MeV Au9+ ions of fluences 1×1013 and 4×1013 ions/cm2. Techniques like X-ray reflectivity (XRR), cross-sectional transmission electron microscopy (X-TEM) and DC magnetization with a vibrating sample magnetometer (VSM) are used for structural and magnetic characterization of pristine and irradiated MLS. Analysis of XRR data using Parratt’s formalism shows a significant increase in W/Fe layer roughness. X-TEM studies reveal that intra-layer microstructure of Fe layers in MLS becomes nano-crystalline on irradiation. DC magnetization study shows that with spacer layer thickness interlayer coupling changes between ferromagnetic to antiferromagnetic.

Bagchi, Sharmistha; Jani, Snehal; Anwar, Shahid; Lakshmi, N.; Lalla, N. P.

2010-12-01

348

Effect of swift heavy ion irradiation on ethylene-chlorotrifluoroethylene copolymer  

NASA Astrophysics Data System (ADS)

The swift heavy irradiation induced changes taking place in ethylene-chlorotrifluoroethylene (E-CTFE) copolymer films were investigated in correlation with the applied doses. Samples were irradiated in vacuum at room temperature by lithium (50 MeV), carbon (85 MeV), nickel (120 MeV) and silver (120 MeV) ions with the fluence in the range of 1×1011-3×1012 ions cm-2. Structural and thermal properties of the irradiated as well as pristine E-CTFE films were studied using FTIR, UV-visible, TGA, DSC and XRD techniques. Swift heavy ion irradiation was found to induce changes in E-CTFE depending upon the applied doses.

Singh, Lakhwant; Devgan, Kusum; Samra, Kawaljeet Singh

2012-11-01

349

Effects of temperature change on microstructural evolution in vanadium alloys under ion irradiation up to high damage levels  

Microsoft Academic Search

Recently, it has been pointed out that temperature change under irradiation strongly affects the microstructural evolution of materials. From an engineering point of view, it is very important to investigate the effects of temperature change under irradiation up to high damage levels. Ion irradiations were conducted in the High Fluence Irradiation Facility (HIT) up to 25 dpa. Both upward and

N. Nita; T. Yamamoto; T. Iwai; K. Yasunaga; K. Fukumoto; H. Matsui

2002-01-01

350

Grain growth and phase stability of nanocrystalline cubic zirconia under ion irradiation  

SciTech Connect

Grain growth, oxygen stoichiometry, and phase stability of nanostructurally stabilized cubic zirconia (NSZ) are investigated under 2 MeV Au-ion bombardment at 160 and 400 K to doses up to 35 displacements per atom (dpa). The NSZ films are produced by ion-beam-assisted deposition technique at room temperature with an average grain size of 7.7 nm. The grain size increases with irradiation dose to {approx}30 nm at {approx}35 dpa. Slower grain growth is observed under 400 K irradiations, as compared to 160 K irradiations, indicating that the grain growth is not thermally activated and irradiation-induced grain growth is the dominating mechanism. While the cubic structure is retained and no new phases are identified after the high-dose irradiations, oxygen reduction in the irradiated NSZ films is detected. The ratio of O to Zr decreases from {approx}2.0 for the as-deposited films to {approx}1.65 after irradiation to {approx}35 dpa. The loss of oxygen suggests a significant increase in oxygen vacancies in nanocrystalline zirconia under ion irradiation. The oxygen deficiency may be essential in stabilizing the cubic phase to larger grain sizes.

Zhang Yanwen; Jiang Weilin; Wang Chongmin; Edmondson, Philip D.; Zhu Zihua; Gao Fei [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States); Namavar, Fereydoon [University of Nebraska Medical Center, Omaha, Nebraska 68198 (United States); Lian Jie [Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Weber, William J. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2010-11-01

351

Defects in 700 keV oxygen ion irradiated ZnO  

NASA Astrophysics Data System (ADS)

It is well known that energetic oxygen ions induce heavy crystalline disorder in ZnO, however, systematic study on this regard is very much limited. Here, we present photoluminescence (PL), optical absorption and sheet resistance measurements on poly and single crystalline ZnO samples irradiated with 700 keV O ions. Results have been compared with the effects of 1.2 MeV Ar irradiation on similar ZnO target. Colour change of the samples with increasing O irradiation fluence has also been noted. Non-monotonic variation of room temperature sheet resistance with the increase of fluence has been observed for polycrystalline ZnO. Such an outcome has been understood as point defects transforming to bigger size clusters. Near band edge (NBE) PL emission is largely reduced due to O ion irradiation. However, at 10 K NBE emission can be observed for irradiated polycrystalline samples. Irradiated ZnO single crystal does not show any band to band transition even at 10 K. It is evident that dynamic recovery of defects is more effective in polycrystalline samples. Ultraviolet–visible absorption spectrum of the irradiated ZnO crystal show pronounced sub-band gap absorption. Oxygen irradiation generated new absorption band in ZnO is at 3.05 eV. In the light of earlier reports, this particular band can be ascribed to absorption by neutral oxygen vacancy defects.

Pal, S.; Sarkar, A.; Chattopadhyay, S.; Chakrabarti, Mahuya; Sanyal, D.; Kumar, P.; Kanjilal, D.; Rakshit, T.; Ray, S. K.; Jana, D.

2013-09-01

352

Study on depth profile of heavy ion irradiation effects in poly(tetrafluoroethylene-co-ethylene)  

NASA Astrophysics Data System (ADS)

High linear energy transfer (LET) heavy ion beams were used to irradiate poly(tetrafluoroethylene-co-ethylene) (ETFE) under vacuum and in air. The irradiation effects in ETFE as a function of the depth were precisely evaluated by analyzing each of the films of the irradiated samples, which were made of stacked ETFE films. It was indicated that conjugated double bonds were generated by heavy ion beam irradiation, and their amounts showed the Bragg-curve-like distributions. Also, it was suggested that higher LET beams would induce radical formation in high density and longer conjugated C=C double bonds could be generated by the second-order reactions. Moreover, for samples irradiated in air, C=O was produced correlating to the yield of oxygen molecules diffusing from the sample surface.

Gowa, Tomoko; Shiotsu, Tomoyuki; Urakawa, Tatsuya; Oka, Toshitaka; Murakami, Takeshi; Oshima, Akihiro; Hama, Yoshimasa; Washio, Masakazu

2011-02-01

353

Microstructural changes of T-91 alloy irradiated by Fe self ions to ultrahigh displacement ratios  

NASA Astrophysics Data System (ADS)

Modified 9Cr-1Mo steel T91, a candidate material for structural components in fission reactors, was irradiated with 3.5 MeV Fe ions at 450 °C to 150 displacements per atom. Transmission electron microscopy and scanning transmission electron microscopy were used to characterize the microstructure and microchemistry changes. We found that irradiation can induce formation of needle-like M3C particles, in addition to voids and tangled dislocations. But for these preexisting precipitates their compositions remain roughly the same before and after the irradiation. Furthermore, we did not observe either Cr depletion or Cr enrichment at grain and subgrain boundaries after the irradiation.

Wei, C. C.; Aitkaliyeva, A.; Martin, M. S.; Chen, D.; Shao, L.

2013-07-01

354

In-situ observation of xenon nanocrystals in aluminum under electron and ion irradiation in transmission electron microscope  

Microsoft Academic Search

In-situ ion irradiation in the transmission electron microscope (TEM) is one of the unique techniques to investigate the structural evolution of materials induced by particle bombardments. In spite of many efforts to get clear results from in-situ ion irradiation, the results were sometimes unclear because of physical and technical problems associated with TEM and ion beam hardwares. This paper describes

Furuya

1998-01-01

355

Ion-irradiation effects in Tl2Ca2Ba2Cu3O10 superconductors  

NASA Astrophysics Data System (ADS)

The effects of oxygen and helium ion irradiation on the superconducting properties of Tl2Ca2Ba2Cu3O10 thin films were investigated. The transition temperature and width were monitored as a function of ion fluence using both magnetization and resistivity measurements. These data suggest that superconductivity is completely suppressed at 0.020 dpa for both He and O ion irradiation. Further, the rate of decrease in (Tc) as a function of deposited energy showed that the dominant mechanism causing damage-induced suppression of (Tc) in these films was from atomic collisions.

Barbour, J. C.; Kwak, J. F.; Venturini, E. L.; Ginley, D. S.; Peercy, P. S.

356

Improvement in both giant magnetoresistance and exchange bias through hydrogen ion irradiation at low energy  

SciTech Connect

Irradiation of IrMn-based spin valves with 550 eV hydrogen ions increased their giant magnetoresistance and exchange bias by 20% and 60%, respectively. This significant enhancement stems from the strong (111) texture and small mosaic spread of the IrMn antiferromagnet that resulted from the microstructural reconstruction caused by the energy transfer during the bombardment by hydrogen ions, as well as by the narrow dispersion in the exchange bias. Irradiation with the hydrogen ion at low energy can improve the properties of spin valves without resulting in undue degradation in the performance or the microstructure.

Shim, Jaechul; Han, Yoonsung; Lee, Jinwon; Hong, Jongill [Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

2008-09-01

357

Ion-irradiation-induced densification of zirconia sol-gel thin films  

SciTech Connect

We have investigated the densification behavior of sol-gel zirconia films resulting from ion irradiation. Three sets of films were implanted with neon, krypton, or xenon. The ion energies were chosen to yield approximately constant energy loss through the film and the doses were chosen to yield similar nuclear energy deposition. Ion irradiation of the sol-gel films resulted in carbon and hydrogen loss as indicated by Rutherford backscattering spectrometry and forward recoil energy spectroscopy. Although the densification was hypothesized to result from target atom displacement, the observed densification exhibits a stronger dependence on electronic energy deposition.

Levine, T.E.; Giannelis, E.P. [Cornell Univ., Ithaca, NY (United States). Dept. of Materials Science and Engineering; Kodali, P.; Tesmer, J.; Nastasi, M. [Los Alamos National Lab., NM (United States); Mayer, J.W. [Arizona State Univ., Tempe, AZ (United States)

1994-02-01

358

Heavy-ion irradiation effects on structures and acid dissolution of pyrochlores  

Microsoft Academic Search

The temperature dependence of the critical dose for amorphization, using 0.6 MeV Bi+ ions, for A2Ti2O7 pyrochlores, in which A=Y, Sm, Gd and Lu, exhibits no significant effect of A-site ion mass or size. The room temperature dose for amorphization was found to be ?0.18 dpa in each case. After irradiation with 2 MeV Au2+ ions glancing-incidence X-ray diffraction (XRD)

Bruce D. Begg; Nancy J. Hess; William J. Weber; Ram Devanathan; Jonathan P. Icenhower; Suntharampillai Thevuthasan; B PETER. McGrail

2001-01-01

359

Swift heavy ion irradiation induced phase transformation in calcite single crystals  

Microsoft Academic Search

Ion irradiation induced phase transformation in calcite single crystals have been studied by means of Raman and infrared spectroscopy using 120 MeV Au9+ ions. The observed bands have been assigned according to group theory analysis. For higher fluence of 5×1012 ion\\/cm2, an extra peak on either side of the 713 cm?1 peak and an increase in the intensity of 1085 cm?1 peak were observed in Raman

H. Nagabhushana; B. M. Nagabhushana; B. N. Lakshminarasappa; Fouran Singh; R. P. S. Chakradhar

2009-01-01

360

Ion and electron beam irradiation effects for highT c superconducting thin films  

Microsoft Academic Search

Ion and Electron Beam irradiation effects for Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O superconducting thin films are investigated. By measuring ion and electron dose dependencies of resistivity versus temperature, it became clear that the crystal structure of a Bi system thin film is destroyed with a lower ion and electron dose, than for a Y system thin film. Moreover, it is conformed that

S. Matsui; H. Matsutera; T. Yoshitake; J. Fujita; T. Ichihashi; M. Mito

1992-01-01

361

Elastic collisions in ion irradiation experiments: A mechanism for space weathering of silicates  

Microsoft Academic Search

Ion irradiation experiments have been performed on silicates (bulk samples) rich of olivine, pyroxene, and serpentine to simulate the effects of space weathering induced on asteroids by solar wind ions. We have used different ions (H+, He+, Ar+, Ar2+) having different energies (from 60 to 400 keV) to weather the samples, probed by Raman spectroscopy and UV–vis–NIR reflectance spectroscopy. All

Rosario Brunetto; Giovanni Strazzulla

2005-01-01

362

Magnetic states controlled by energetic ion irradiation in FeRh thin films  

SciTech Connect

Changes in magnetic properties and lattice structure of FeRh films by 180 keV-10 MeV ion (H, He, and I) irradiation are studied. In spite of the irradiation with different ion species and wide range of energies, the changes in magnetization are dominated by solely a single parameter; the density of energy which is deposited through elastic collision between the ions and the samples. For the low deposition energy density, the magnetization increases with increasing the deposition energy density, while the lattice structure remains unchanged. When the deposition energy density becomes larger, however, the magnetization decreases after reaching the maximum value. The decrease in the magnetization accompanies the crystal structure change from B2 to A1. The present results imply that the magnetic state of FeRh films can be designedly controlled by the energetic ion irradiations.

Fujita, Nao.; Kosugi, S.; Matsui, T.; Iwase, A. [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Saitoh, Y. [Japan Atomic Energy Agency (JAEA-Takasaki), Takasaki, Gumma 370-1292 (Japan); Kaneta, Y. [Department of Systems Innovation, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Kume, K.; Batchuluun, T. [The Wakasa Wan Energy Research Center (WERC), 64-52-1 Tsuruga, Fukui 914-0192 (Japan); Ishikawa, N. [Japan Atomic Energy Agency (JAEA-Tokai), Tokai, Ibaraki 319-1195 (Japan)

2010-05-15

363

Pattern-induced magnetic anisotropy in FePt thin films by ion irradiation  

SciTech Connect

The magnetic properties of FePt thin films have been modified by exposing the samples to irradiation of 4 MeV Cl{sup 2+} ions. Patterned magnetic films, without modified topographical profile, were fabricated by irradiating the films through a shadowing micrometric mask. The structural changes, ascribed to the ion-beam-induced amorphization of the thin films, promote the modification of the magnetic anisotropy. In particular, the out-of-plane component of the magnetization decreases simultaneously with an enhancement of in-plane anisotropy by increasing ion fluence. Moreover, the nonirradiated regions present unexpected anisotropic behavior owing to the stray field of the irradiated regions. The control of this effect, which can have unwished consequences for the patterning of magnetic properties by ion bombardment, needs to be suitably addressed.

Jaafar, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, ES-28049 Madrid (Spain); Dpto. Fisica de la Materia Condensada, UAM, ES-28049 Madrid (Spain); Sanz, R. [Instituto de Ciencia de Materiales de Madrid, CSIC, ES-28049 Madrid (Spain); Nanoate SL, Poeta Rafael Morales 2, ES-28702 San Sebastian de los Reyes, Madrid (Spain); McCord, J. [Institute of Ion Beam Physics and Materials Research, FZD, D-01314 Dresden (Germany); Jensen, J. [Thin Film Physics, Department of Physics, Chemistry and Biology, Linkoeping University, SE-581 83 Linkoeping (Sweden); Schaefer, R. [Leibniz Institute for Solid State and Materials Research, IFW, Helmholtzstrasse 20, D-01069 Dresden (Germany); Vazquez, M.; Asenjo, A. [Instituto de Ciencia de Materiales de Madrid, CSIC, ES-28049 Madrid (Spain)

2011-03-01

364

Investigation of lipid peroxidation in liposomes induced by heavy ion irradiation.  

PubMed

Lipid peroxidation induced by heavy ion irradiation was investigated in 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLPC) liposomes. Lipid peroxidation was induced using accelerated heavy ions that exhibit linear energy transfer (LET) values between 30 and 15000 keV/microm and doses up to 100 kGy. With increasing LET, the formation of lipid peroxidation products such as conjugated dienes, lipid hydroperoxides, and thiobarbituric acid-reactive substances decreased. When comparing differential absorption spectra and membrane fluidity following irradiation with heavy ions and x-rays (3 Gy/min), respectively, it is obvious that there are significant differences between the influences of densely and sparsely ionizing radiation on liposomal membranes. Indications for lipid fragmentation could be detected after heavy ion irradiation. PMID:9728741

Ziegler, C; Wessels, J M

1998-07-01

365

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

366

A NRA study of temperature and heavy ion irradiation effects on helium migration in sintered uranium dioxide  

NASA Astrophysics Data System (ADS)

Helium implanted uranium dioxide sintered samples were studied using nuclear reaction analysis prior to and following heavy ion irradiations and temperature anneals at 800 °C and 1100 °C. The results show that the heavy ion irradiations do not produce measurable long range movement of helium atoms. However, the ion irradiations do affect the behaviour of helium during subsequent temperature anneals. As regards the 800 °C anneal, the reduced mobility of helium in the ion-irradiated samples is interpreted as resulting from enhanced helium atom segregation produced by the ion-irradiation. Conversely at 1100 °C, the initial heavy ion irradiation appears to produce a greater than expected movement of helium within the bulk of the sample which could be an indication of defect assisted helium diffusion. Thermal diffusion coefficients are also reported at 800 °C and 1100 °C based on an analysis using a one-dimensional diffusion model.

Martin, G.; Garcia, P.; Labrim, H.; Sauvage, T.; Carlot, G.; Desgardin, P.; Barthe, M. F.; Piron, J. P.

2006-10-01

367

Irradiation effects of 25 MeV silicon ions on SiGe heterojunction bipolar transistors  

NASA Astrophysics Data System (ADS)

Silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs) were exposed to 25 MeV Si4+ ion with equivalent absorbed dose from 200 krad(Si) to 10 Mrad(Si). The transistor characteristics such as forward Gummel, reverse Gummel, leakage current of base–emitter (BE) junction and base–collector (BC) junction were studied before and after irradiation and were used to quantify the dose tolerance to the swift heavy ion irradiation. The base current was found more sensitive than collector current and current gain appeared to decline with the ion fluence increasing. On the reverse Gummel characteristics, besides the degradation in the base current, an unexpected increase in emitter current was observed with the ion fluence increasing. The output characteristics of the irradiated SiGe HBTs exhibited a decrease in the collector current with the increasing ion fluence. The reverse leakage current of BE and BC junctions increased with the increase in ion fluence. The self-annealing effect at room temperature was found less influence on the performance degradation. The displacement damages in the transistor were found to dominate the performance degradation of SiGe HBT after 25 MeV Si4+ ion irradiation.

Sun, YaBin; Fu, Jun; Xu, Jun; Wang, YuDong; Zhou, Wei; Zhang, Wei; Cui, Jie; Li, GaoQing; Liu, ZhiHong

2013-10-01

368

Heavy ion range anisotropy in muscovite mica  

NASA Astrophysics Data System (ADS)

The anisotropy of heavy ion range in layered crystal of muscovite mica has been studied in the present investigation. The freshly cleaved basal plane of the natural muscovite mica has been irradiated with various energetic heavy ions with different dip angles from UNILAC (Universal Linear Accelerator) heavy ion accelerator, GSI, Darmstadt, Germany. We have tried to investigate the causes and effects of the anisotropic nature of the layered crystalline mica on heavy ions propagation. The measured and available range values of number of heavy ions [viz: 58Ni; 93Nb; 129Xe; 132Xe; 197Au; 208Pb; 209Bi; and 238U] in muscovite mica are used to highlight the shortcomings of various range and energy loss formulations about the orientation effect on stopping processes in anisotropic media.

Singh, Mohan; Kaur, Navjeet; Singh, Lakhwant

2010-09-01

369

Isotope effect between hydrogen and deuterium ion irradiation on titanium carbide (TiC) at low temperature  

Microsoft Academic Search

Damage evolution and amorphization in TiC due to He+, H2+ and D2+ ion irradiation at low temperature were examined by in-situ electron microscopy and EELS observation. He+ ion irradiation at 20 K results in the production of a number of dislocation loops and bubbles but no amorphization. 10 keV H2+ ion irradiation at 20 K causes amorphization at a fluence

K. Hojou; H. Otsu; S. Furuno; N. Sasajima; K. Izui

1997-01-01

370

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

371

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

372

MeV Au ion irradiation in silicon and nanocrystalline zirconia film deposited on silicon substrate  

NASA Astrophysics Data System (ADS)

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

2012-09-01

373

Production of sp3 hybridization by swift heavy ion irradiation of HOPG  

NASA Astrophysics Data System (ADS)

Highly oriented pyrolytic graphite (HOPG) samples were irradiated by swift heavy ions (86Kr, 209Bi and 238U) with the fluence of 1011-1013 ions/cm2 at room temperature. The production of sp3 hybridization by the irradiation process has been confirmed directly by X-ray photoelectron spectroscopy (XPS). In this work, both irradiated and pristine HOPG samples were investigated by XPS and Raman spectroscopy. The existence of sp3 component is confirmed on the surface of the irradiated HOPG samples. XPS result shows that the acreage ratio Isp3/Isp2 increases with the ion fluence and saturates at a higher value of irradiation. It is found that the amount of hybridization (Isp3/Isp2) strongly depends on the electronic energy loss in the sample. Raman spectra of the irradiated samples show the increasing of acreage ratio ID/IG with the ion fluence, which indicates the change of the atomic structure and the phase transition from sp2 to sp3.

Zeng, J.; Zhai, P. F.; Liu, J.; Yao, H. J.; Duan, J. L.; Hou, M. D.; Sun, Y. M.; Li, G. P.

2013-07-01

374

Enhanced electron field emission from carbon nanotubes irradiated by energetic C ions.  

PubMed

The field emission performance and structure of the vertically aligned multi-walled carbon nanotube arrays irradiated by energetic C ion with average energy of 40 keV have been investigated. During energetic C ion irradiation, the curves of emission current density versus the applied field of samples shift firstly to low applied fields when the irradiation doses are less than 9.6 x 10(16) cm(-2), and further increase of dose makes the curves reversing to a high applied field, which shows that high dose irradiation in carbon nanotube arrays makes their field emission performance worse. After energetic ion irradiation with a dose of 9.6 x 1016 cm(-2), the turn-on electric field and the threshold electric field of samples decreased from 0.80 and 1.13 V/microm to 0.67 and 0.98 V/microm respectively. Structural analysis of scanning electron microscopy, transmission electron microscopy and Raman spectroscopy indicates that the amorphous carbon nanowire/carbon nanotube hetero nano-structures have been fabricated in the C ion irradiated carbon nanotubes. The enhancement of electron field emission is due to the formation of amorphous carbon nanowires at the tip of carbon nanotube arrays, which is an electron emitting material with low work function. PMID:22962775

Sun, Peng-Cheng; Deng, Jian-Hua; Cheng, Guo-An; Zheng, Rui-Ting; Ping, Zhao-Xia

2012-08-01

375

Buried amorphous layers by electronic excitation in ion-beam irradiated lithium niobate: Structure and kinetics  

SciTech Connect

The formation of buried heavily damaged and amorphous layers by a variety of swift-ion irradiations (F at 22 MeV, O at 20 MeV, and Mg at 28 MeV) on congruent LiNbO{sub 3} has been investigated. These irradiations assure that the electronic stopping power S{sub e}(z) is dominant over the nuclear stopping S{sub n}(z) and reaches a maximum value inside the crystal. The structural profile of the irradiated layers has been characterized in detail by a variety of spectroscopic techniques including dark-mode propagation, micro-Raman scattering, second-harmonic generation, and Rutherford backscattering spectroscopy/channeling. The growth of the damage on increasing irradiation fluence presents two differentiated stages with an abrupt structural transition between them. The heavily damaged layer reached as a final stage is optically isotropic (refractive index n=2.10, independent of bombarding ion) and has an amorphous structure. Moreover, it has sharp profiles and its thickness progressively increases with irradiation fluence. The dynamics under irradiation of the amorphous-crystalline boundaries has been associated with a reduction of the effective amorphization threshold due to the defects created by prior irradiation (cumulative damage). The kinetics of the two boundaries of the buried layer is quite different, suggesting that other mechanisms aside from the electronic stopping power should play a role on ion-beam damage.

Olivares, J.; Garcia-Navarro, A.; Garcia, G.; Agullo-Lopez, F.; Agullo-Rueda, F.; Garcia-Cabanes, A.; Carrascosa, M. [Instituto de Optica, CSIC, C/Serrano 121, E-28006 Madrid (Spain); Centro de Microanalisis de Materiales (CMAM), Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, Campus de Cantoblanco, E-28049 Madrid (Spain); Departamento de Fisica de Materiales C-IV, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)

2007-02-01

376

Damages in ceramics for nuclear waste transmutation by irradiation with swift heavy ions  

NASA Astrophysics Data System (ADS)

Inert matrices are proposed for advanced nuclear fuels or for the transmutation of the actinides that is an effective solution for the nuclear waste management. The behaviour of inert matrix ceramics like MgO, MgAl2O4 and cubic ZrO2 oxides under irradiation is presented in this study. The alumina Al2O3 has been also studied as a reference for the ceramic materials. These oxides have been irradiated with swift heavy ions at CIRIL/GANIL to simulate the fragment fission effects. The irradiations with the different heavy ions (from S to Pb) with energy between 91 and 820 MeV, have been realised at room temperature or 500 °C. The fluencies were between 5 × 1010 and 5 × 1015 ions/cm2. The polished faces of sintered polycrystalline disks or single crystal slices have been characterized before and after irradiation by X-ray diffraction and optical spectroscopy. The apparent swelling evaluated from surface profile measurements after irradiation is very important for spinel and zirconia, comparatively with those of magnesia or alumina. The amorphisation seems to be at the origin of this swelling, and the electronic stopping power of the ions is the most influent parameter for the irradiation damages. The point defects characterized by optical spectroscopy show a significant amount of damage on the oxygen sub-lattice in the irradiated oxides. F+ centres are present in all irradiated oxides. However, new absorption bands are observed and cation clusters cannot be excluded in magnesia and spinel after irradiation.

Beauvy, Michel; Dalmasso, Chrystelle; Thiriet-Dodane, Catherine; Simeone, David; Gosset, Dominique

2006-01-01

377

Modeling of the LIFE minichamber Xe theta pinch experiment  

NASA Astrophysics Data System (ADS)

The LIFE minichamber experiment is being designed to investigate cooling of the Xe buffer gas protecting the LIFE chamber wall. A magnetically driven theta pinch configuration will be used to inductively heat a few-cm long cylinder of Xe at ion density 2e16/cc to several eV. Thomson scattering will be used to determine the electron temperature and ionization state of the strongly radiating, cooling Xe. The experiment is being modeled using the magnetohydrodynamic code HYDRA with an external circuit mode and inductive feedback from the plasma to the external circuit. Designing the experiment is challenging due to the current paucity of opacity and conductivity data for Xe in the buffer gas regime of temperature and density. Results of the modeling will be presented.

Kane, Jave; Rhodes, Mark; Loosmore, Gwendolen; Latkowski, Jeffery; Koning, Joseph; Patel, Mehul; Zimmerman, George; Demuth, James; Moses, Gregory

2010-11-01

378

Dynamical response of helium bubble motion to irradiation with high-energy self-ions in aluminum at high temperature.  

SciTech Connect

Brownian-type motion of helium bubbles in aluminum and its dynamical response to irradiation with 100-keV Al{sup +} ions at high temperatures has been studied using in situ irradiation and transmission electron microscopy. It is found that, for most bubbles, the Brownian-type motion is retarded under irradiation, while the mobility returns when the irradiation is stopped. In contrast, under irradiation, a small number of bubbles display exceptionally rapid motion associated with the change in bubble size. These effects are discussed in terms of the dynamical interaction of helium bubbles with cascade damage formed by the high-energy self-ion irradiation.

Ono, K.; Miyamoto, M.; Arakawa, K.; Birtcher, R. C.; Materials Science Division; Shimane Univ.; Osaka Univ.

2009-02-21

379

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

380

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

2012-02-10

381

Heavy ion irradiation induced dislocation loops in AREVA's M5® alloy  

NASA Astrophysics Data System (ADS)

Pressurized water reactor (PWR) Zr-based alloy structural materials show creep and growth under neutron irradiation as a consequence of the irradiation induced microstructural changes in the alloy. A better scientific understanding of these microstructural processes can improve simulation programs for structural component deformation and simplify the development of advanced deformation resistant alloys. As in-pile irradiation leads to high material activation and requires long irradiation times, the objective of this work was to study whether ion irradiation is an applicable method to simulate typical PWR neutron damage in Zr-based alloys, with AREVA's M5® alloy as reference material. The irradiated specimens were studied by electron backscatter diffraction (EBSD), positron Doppler broadening spectroscopy (DBS) and in situ transmission electron microscopy (TEM) at different dose levels and temperatures. The irradiation induced microstructure consisted of - and -type dislocation loops with their characteristics corresponding to typical neutron damage in Zr-based alloys; it can thus be concluded that heavy ion irradiation under the chosen conditions is an excellent method to simulate PWR neutron damage.

Hengstler-Eger, R. M.; Baldo, P.; Beck, L.; Dorner, J.; Ertl, K.; Hoffmann, P. B.; Hugenschmidt, C.; Kirk, M. A.; Petry, W.; Pikart, P.; Rempel, A.

2012-04-01

382

Anisotropic magnetism of graphite irradiated with medium-energy hydrogen and helium ions  

NASA Astrophysics Data System (ADS)

We have studied the changes in the magnetic behavior of highly oriented pyrolytic graphite (HOPG) samples subjected to medium-energy proton and helium irradiation. The variations of the ferromagneticlike magnetization curves with the irradiation dose have been studied for two configurations: magnetic fields parallel and perpendicular to graphitic planes. For high irradiation doses, the values of magnetization at saturation are close for both geometries. At low irradiation fluences an orientationally dependent magnetic response is obtained. Directional dependence of magnetization indicates that the magnetism in irradiated graphite is triggered by vertically aligned intrinsic carbon defects induced by irradiation. This physical picture has been verified by the observation of a local stray field near linear defects by means of magnetic force microscopy. Similar results obtained with hydrogen and helium ions confirm that the chemical nature of projectiles is not crucial for formation of ferromagnetic order in oriented graphite. The dependence of induced magnetic moment versus irradiation dose shows a maximum; the optimal dose is an order of magnitude less for helium ions than for protons, being in line with simulations showing that He+ generates 8 times more defects than H+. Raman studies indicate that the degradation of magnetic ordering at large irradiation doses occurs much earlier than graphite amorphization but coincides with the destruction of graphene sheet stacking.

Makarova, T. L.; Shelankov, A. L.; Serenkov, I. T.; Sakharov, V. I.; Boukhvalov, D. W.

2011-02-01

383

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.

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

2013-01-01

384

Biodamage via shock waves initiated by irradiation with ions.  

PubMed

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

385

Charge-exchange EUV spectroscopy in collisions of Xe{sup q+} (q=7-9) with rare gases  

SciTech Connect

Extreme ultraviolet (EUV) emission spectra have been measured in charge exchange collisions between Xe{sup q+} (q=7--9) and rare gases at an energy of 20 q keV. We have observed 4, 22, and 39 lines in collisions of Xe{sup 7+}, Xe{sup 8+}, and Xe{sup 9+}. Of these emission lines, four lines of Xe vii, eight lines of Xe viii, and nine lines of Xe ix correspond to newly observed transitions. The identification procedure is described in detail. The aim of this work is to obtain spectroscopic data for multiply charged Xe ions. In addition, the electron capture mechanism is also discussed using the crude classical over-the-barrier model to understand the target dependence of the emission spectra.

Tanuma, H.; Ohashi, H.; Yamamoto, N.; Kato, D.; Murakami, I.; Fujioka, S.; Nishimura, H.; Nishihara, K. [Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo 192-0397 (Japan); National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2011-10-15

386

Physical and chemical response of 145 MeV Ne6+ ion irradiated polymethylmethacrylate (PMMA) polymer  

NASA Astrophysics Data System (ADS)

Characterization of ion induced modifications in the physical, chemical and structural properties of polymethylmethacrylate (PMMA) polymer induced by 145 MeV Ne6+ ions has been carried out by FTIR, UV-Visible, Differential scanning calorimetry (DSC) and X-ray diffraction. Heavy ion irradiation was carried out under a vacuum of ˜10-6 torr at Variable Energy Cyclotron Centre, Kolkata, India using a low beam current (˜15 nA). Ion fluences of 1010, 1011, 1012, 1013 ions/cm2 were used. The optical band gap (Eg), calculated from the absorption edge of the UV-Vis spectra of these films in 200-800 nm region varied from 2.167 eV to 1.512 eV for virgin and irradiated samples. In FTIR spectra appreciable changes have been observed after irradiation, indicating the molecular fragmentation, cross-linking, formation of unsaturated groups and free radicals. DSC thermograms give information about the thermal stability and type of thermal reactions (exothermic/endothermic) on the application of heat to the polymer. XRD analyses show slight shift of peak position and significant changes in peak intensity. XRD results show a decrease of ˜4.12% in crystallite size of irradiated sample at the higher fluence of 1012 ions/cm2.

Kumar, Rajesh; Ali, S. A.; Singh, Paramjit; de, U.; Virk, H. S.; Prasad, Rajendra

2011-07-01

387

Sputtering and surface topography modification of bismuth thin films under swift 84Kr15+ ion irradiation  

NASA Astrophysics Data System (ADS)

The sputtering and surface topography modification of bismuth thin films deposited onto Si substrates and irradiated by 27.5 MeV 84Kr15+ ions over the fluence range 1012-1014 cm-2 have been studied using three complementary techniques: Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM) and X-ray diffraction (XRD). The RBS analysis reveals a linear reduction of the initial thickness of the irradiated bismuth samples by ˜4% up to 7% with increasing ion fluence corresponding to a mean sputtering yield of ˜2.9 × 102 at/ion. Besides, significant sample surface topography changes occur upon ion irradiation consisting in grain growth and surface roughening clearly pointed out by performed AFM and XRD analyses. Moreover, a close correlation is observed between the variations versus ion fluence of the measured sputtering yield and the determined Bi surface grain size and compressive strain. These moderate Bi surface effects are similar to those pointed out previously for thin films irradiated by MeV heavy ions. They can be mainly caused by inelastic electronic collision mechanisms taking place within the Bi material electronic stopping power regime below the threshold for latent track formation.

Mammeri, S.; Ouichaoui, S.; Ammi, H.; Pineda-Vargas, C. A.; Dib, A.; Msimanga, M.

2012-12-01

388

Ultra-fast luminescence in heavy-ion track-cores in insulators: Electron–hole plasma  

Microsoft Academic Search

Measurements of fast luminescence decays and time-resolved spectra reveal novel ultra-short-lived luminescence (several tens ps) in N-, Ar-, Kr- and Xe-ion irradiated single crystals of 12 kinds of alkali halides, two alkaline-earth halides, three oxides and one semiconductor, but no such luminescence by He-ion irradiation. The luminescence spectrum covers a region, from UV to VIS (in some oxides, from VUV).

Kazuie Kimura

2003-01-01

389

Structural properties of embedded Ge nanoparticles modified by swift heavy-ion irradiation  

NASA Astrophysics Data System (ADS)

Silica-embedded Ge nanoparticles (NPs) of different sizes irradiated with swift heavy ions (SHIs) at a given energy may reportedly elongate along the incident ion direction, perpendicular to it, or not at all. Here, for a given NP size distribution, we have investigated the SHI energy dependence of the elongation process. Higher-energy irradiation generally yielded elongation along the ion track (as previously observed), but for lower-energy irradiation, elongation both parallel and perpendicular to the ion direction was observed. We demonstrate that NP size and electronic energy loss together govern the elongation process, reinforcing the proposed model where elongation perpendicular to the ion direction is only expected for Ge NPs bigger than the mean ion track diameter in silica. Here, a wide fluence range is also probed, enabling us to follow in more detail the transition from spherical unirradiated Ge NPs to Ge NPs elongated either parallel or perpendicular to the ion beam. X-ray absorption spectroscopy (XAS) measurements are utilized for the quantification of crystalline, amorphous, and oxidized environments around Ge atoms. Combining such results with transmission electron microscopy (TEM) observations shows the Ge NPs are rendered amorphous prior to elongation, potentially via a melt-and-quench process. Thereafter, stronger electron-phonon coupling in amorphous Ge compared to crystalline Ge may potentially influence the elongation process. The Ge NP amorphization occurs at lower fluences for higher irradiation energies, indicating electronic energy loss—and not ballistic effects—governs the amorphization. Subsequent to amorphization and elongation, TEM and XAS results also show the NPs gradually intermix with SiO2 and dissolve within the matrix as the irradiation fluence increases. We discuss the impact of such results in the ion beam tailoring of Ge NPs for technological applications.

Araujo, L. L.; Giulian, R.; Sprouster, D. J.; Schnohr, C. S.; Llewellyn, D. J.; Johannessen, B.; Byrne, A. P.; Ridgway, M. C.

2012-06-01

390

Ion dose dependence of the sputtering yield: Ar{sup +}, Ne{sup +}, and Xe{sup +} bombardment of Ru(0001) and Al(111)  

SciTech Connect

The sputtering yield from clean metal surfaces has long been considered to be insensitive to primary ion dose at moderate ion fluences (< 10{sup 18} ions/cm{sup 2}). Using carefully cleaned and well-characterized targets, the ion dose dependence of the sputtering yield of Ru(0001) and Al(111) has been investigated. The sputtering yield of Ru(0001) is found to decrease substantially following primary ion bombardment at low fluences, while the sputtering yield of Al(111) exhibits no fluence dependence at low primary ion dose. Using secondary neutral mass spectrometry (SNMS), the sputtering yield of ruthenium was observed to decrease following ion bombardment by argon, xenon, and neon. High-detection-efficiency time-of-flight mass spectrometry was coupled with nonresonant laser ionization to allow real-time sputtering yield measurements and to minimize target damage during data collection. The experiments show that the sputtering yield of Ru(0001) decreases by 50%, following a primary ion fluence of, less than 10{sup 16} ions/cm{sup 2} for sputtering by either argon or neon ions and by 25%, following primary ion fluences of less than 10{sup 14} ions/cm{sup 2} for sputtering by xenon. The small size of the experimentally determined damage cross section suggests that microscopic changes in the surface structure cause the observed sputtering yield depression. In contrast to the ruthenium results, the sputtering yield of Al(111) appears to be insensitive to primary ion fluence at low fluences. Calculations using the TRansport of Ions in Matter (TRIM) Monte Carlo sputtering simulation were carried out to investigate the effect of primary ion implantation upon the sputtering yield of ruthenium as well as the effect of a reduced surface binding energy of ruthenium surface atoms. The TRIM results indicate that neither of these mechanisms can explain the experimentally observed fluence dependence of the sputtering yield of ruthenium.

Burnett, J.W.; Pellin, M.J.; Whitten, J.E.; Gruen, D.M. [Argonne National Lab., IL (United States); Yates, J.T. Jr. [Univ. of Pittsburgh, PA (United States)

1994-04-01

391

Surface reformation and electro-optical characteristics of liquid crystal alignment layers using ion beam irradiation  

SciTech Connect

The surface modification characteristics of liquid crystal (LC) alignment layers irradiated with various argon (Ar) ion beam (IB) energies were investigated as a substitute for rubbing technology. Various pretilt angles were created on the IB-irradiated polyimide (PI) surfaces after IB irradiation, but the Ar ions did not alter the morphology on the PI surface, indicating that the pretilt angle was not due to microgrooves. The chemical bonding states of the IB-irradiated PI surfaces were analyzed in detail by x-ray photoelectron spectroscopy to verify the compositional behavior for the LC alignment. Chemical structure analysis showed that the alignment ability of LCs was due to the preferential reorientation of the carbon network due to the breaking of C=O double bonds in the imide ring parallel to the incident IB direction. The potential of applying nonrubbing technology to display devices was further supported by the superior electro-optical characteristics compared to rubbed PI.

Oh, Byeong-Yun; Lee, Kang-Min; Kim, Byoung-Yong; Kim, Young-Hwan; Han, Jin-Woo; Han, Jeong-Min; Lee, Sang-Keuk; Seo, Dae-Shik [Information Display Device Laboratory, Department of Electrical and Electronic Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

2008-09-15

392

Formation of Si nanocrystals by heavy ion irradiation of amorphous SiO films  

NASA Astrophysics Data System (ADS)

We studied the structural transformations of a-SiO thin films caused by swift heavy ion irradiation at room temperature. Rutherford backscattering spectroscopy, nuclear reaction analysis, transmission electron microscopy and infrared absorption spectrometry have been used in combination to investigate the changes induced by ion irradiation. We show that the homogeneous monoxide is transformed according to the macroscopic reaction: 2SiO -> Si + SiO2. Each ion perturbs a large area (approximately 10-30 nm diameter), 2-3 nm diameter Si clusters are formed inside the track core. A broad photoluminescence at ~ 600 nm is also detected in the irradiated films. This visible light emission is associated with the formation of the perturbed zone.

Rodichev, D.; Lavallard, Ph.; Perriere, J.; Dooryhée, E.; Slaoui, A.; Gandais, M.; Wang, Y.

1996-02-01

393

High-energy C+ ion-irradiated low-density polyethylene (LDPE): Spectroscopic and morphological investigation  

NASA Astrophysics Data System (ADS)

The optical absorption spectra of 3.6 MeV 12C ions irradiated low-density polyethylene (LDPE) show the gradual increase in the optical absorption and the shift from the near UV to the visible region with increase in ion fluence. The increase in absorption may be attributed to the generation of a conjugated system of bonds, which are also corroborated by FTIR. Scanning electron microscopic (SEM) studies reveal that the formation of linear network structure occurred at relatively lower ion fluence of 5×1013 ions/cm2.

Vinodh Kumar, S.; Ghadei, B.; Krishna, J. B. M.; Bhattacharya, S. C.; Saha, A.

2009-05-01

394

Swift heavy ion irradiation and fish tail magnetization in NBCO films - the cause and effect  

NASA Astrophysics Data System (ADS)

NBCO films, prepared by pulsed laser ablation, were irradiated by 200 MeV Au ions. The magnetization curve shows a shoulder/fish tail peak effect (FTPE) in the irradiated film while the pristine or as-grown film does not have any such signature. The absence of FTPE in the preirradiated film and its appearance in the postirradiated film are explained in the context of compositional variation of spatial density of defects and the concomitant vortex mobility .

Khatua, Sanghamitra; Mishra, P. K.; Kulkarni, D. G.; Kumar, Ravi; John, J.; Sahni, V. C.; Pinto, R.

2000-03-01

395

The effects of swift heavy ion irradiation on the radiochemistry and melting characteristics of PET  

Microsoft Academic Search

High electronic excitation (?10 keV\\/nm) induced effects on the radiochemistry and melting behaviour of semicrystalline polyethylene terephthalate (PET) have been studied by FTIR and differential scanning calorimetry (DSC) techniques. After irradiation with a 180 MeV Ag14+ ion beam, DSC measurements of PET films exhibited significant change in their melting behaviour. The gradual increase in the melting enthalpy of irradiated PET

A. Biswas; S Lotha; D Fink; J. P Singh; D. K Avasthi; B. K Yadav; S. K Bose; D. T Khating; A. M Avasthi

1999-01-01

396

Micro-Raman study of the carbonization of polyimide induced by swift heavy ion irradiations  

Microsoft Academic Search

We have done an extensive study of damage of polyimide (Kapton-H) thin films by heavy ion irradiations in the 1 MeVamu?1 energy range. We found that the irradiation-induced insulator–conductor transition proceeds through four stages on the basis of the progressive formation of a 3D graphite-like structure when track overlaps increase. All bulk dc conductivity and paramagnetic center volume density data

J.-M. Costantini; F. Couvreur; J.-P. Salvetat; S. Bouffard

2002-01-01

397

Effect of swift heavy ion irradiation on the hardness of chromium nanorods  

Microsoft Academic Search

The present study reports the use of swift heavy ion irradiation as a means to tailor the hardness of chromium nanorod coatings. Arrays of slanted and straight Cr nanorods, 1-2 m long and 300-500 nm in diameter, were grown by dc magnetron sputter glancing angle deposition on Si(100) substrates patterned with 500 nm diameter polystyrene spheres. The samples were irradiated

Rupali Nagar; B. R. Mehta; J. P. Singha; D. Jain; V. Ganesan; S. V. Kesapragada; D. Gall

2008-01-01

398

Damage-depth profiling of an ion-irradiated polymer by monoenergetic positron beams  

Microsoft Academic Search

Poly(aryl-ether-ether ketone) (PEEK) films irradiated with 1-MeV and 2-MeV O+ ions were exposed to positron beams to measure the positron annihilation Doppler broadening as a function of the positron energy. The annihilation lines recorded at relatively low positron energies were found to become broader with increasing irradiation dose, suggesting that positronium (Ps) formation is inhibited in the damaged regions. The

Yoshinori Kobayashi; Isao Kojima; Shunichi Hishita; Takenori Suzuki; Eiji Asari; Masahiro Kitajima

1995-01-01

399

Structural change of carbon nanotubes produced by Si ion beam irradiation  

Microsoft Academic Search

Multi-walled carbon nanotubes (MWCNTs) were irradiated by 40keV Si ion beam with different doses. The structural change of the MWCNTs was revealed by transmission electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy. The structural characterization after irradiation shows that the formation of amorphous carbon nanowires proceeds through two periods, carbon nanotube – semi-solid amorphous carbon nanowire with hollow structure

Zhichun Ni; Qintao Li; Jinlong Gong; Dezhang Zhu; Zhiyuan Zhu

2007-01-01

400

Microstructure evolution of metallic nanocrystalline thin-films under ion-beam irradiation  

Microsoft Academic Search

The microstructural evolution of nanocrystalline metallic thin-films under ion irradiation, especially grain growth and second-phase precipitation, was studied with detailed in situ experiments, and a theoretical model was developed to explain the results of grain-growth. Free-standing Zr, Pt, Cu and Au, Cu-Fe, and Zr-Fe nanocrystalline thin films prepared by sputter deposition were irradiated in-situ at the Intermediate Voltage Electron Microscope

Djamel Kaoumi

2007-01-01

401

Kr bubble formation in Cu after moderate doses of ion irradiation: the role of radiation vacancies  

Microsoft Academic Search

A TEM study of Kr bubble formation in Cu as a result of ion irradiation in a dose range from 2.5 × 1014 to 5 × 1015 Kr cm-2 and subsequent annealing is presented. For irradiation doses below 5 × 1015 Kr cm-2 no bubbles are observed in as-implan samples. Post-implantation annealing results in formation of Kr bubbles containing solid

D. Kuzminov; C. Templier; E. Raqi; H. Garem

1992-01-01

402

Light ion irradiation creep of Textron SCS6™ silicon carbide fibers  

Microsoft Academic Search

Creep tests were conducted in torsion on Textron SCS-6™ fibers during an irradiation with light ions in the temperature range 500–1000 °C for doses up to 0.16 dpa. The fibers produced by chemical vapor deposition have a similar structure as a silicon carbide composite matrix produced by chemical vapor infiltration. At 600 °C, the irradiation creep curves were characterized by

R. Scholz; R. Mueller; D. Lesueur

2002-01-01

403

Effect of swift heavy ion irradiation on nanocrystalline CaS:Bi phosphors: Structural, optical and luminescence studies  

Microsoft Academic Search

Luminescence studies of CaS:Bi nanocrystalline phosphors synthesized by wet chemical co-precipitation method and irradiated with swift heavy ions (i.e. O7+-ion with 100MeV and Ag15+-ion with 200MeV) have been carried out. The samples have been irradiated at different ion fluences in the range 1×1012–1×1013ions\\/cm2. The average grain size of the samples before irradiation was estimated as 35nm using line broadening of

Vinay Kumar; Ravi Kumar; S. P. Lochab; Nafa Singh

2007-01-01

404

Heavy ion irradiation inhibits in vitro angiogenesis even at sublethal dose.  

PubMed

Angiogenesis is essential for tumor growth and metastasis. Because endothelial cells are genetically stable, they rarely acquire resistance to anticancer modalities, and could, thus, be a suitable target for radiation therapy. Heavy ion radiation therapy has attracted attention as an effective modality for cancer therapy because of its highly lethal effects, but the effects of heavy ion irradiation on in vitro cell function associated with angiogenesis have not been reported. Our study found that in vitro angiogenesis was inhibited by high linear energy transfer carbon ion irradiation even at sublethal dose (0.1 Gy). ECV304 and HUVEC human umbilical vascular endothelial cells were irradiated with 290 MeV carbon ion beams of approximately 110 keV/ micro m or 4 MV X-ray of approximately 1 keV/ micro m. Their adhesiveness and migration to vitronectin or osteopontin were inhibited, and capillary-like tube structures in three-dimensional culture were destroyed after carbon ion irradiation concomitant with the inhibition of matrix metalloproteinase-2 activity, down-regulation of alphaVbeta3 integrin, which is one of the adhesion molecules, slight up-regulation of membrane type1- matrix metalloproteinase, and significant up-regulation of tissue inhibitor of metalloproteinase-2. On the other hand, sublethal X-ray irradiation promoted migration of endothelial cells, and the capillary-like tube structure in three-dimensional culture progressed even after 16 Gy irradiation. These results provide an implication that heavy ion beam therapy could be superior to conventional photon beam therapy in preventive effects on in vitro angiogenesis even at sublethal dose, and might inhibit angiogenesis in vivo. PMID:12874034

Takahashi, Yutaka; Teshima, Teruki; Kawaguchi, Naomasa; Hamada, Yoshinosuke; Mori, Seiji; Madachi, Ayako; Ikeda, Satoko; Mizuno, Hirokazu; Ogata, Toshiyuki; Nojima, Kumie; Furusawa, Yoshiya; Matsuura, Nariaki

2003-07-15

405

Grain growth and phase stability of nanocrystalline cubic zirconia under ion irradiation  

SciTech Connect

Grain growth, oxygen stoichiometry and phase stability of nanostructurally-stabilized zirconia (NSZ) in pure cubic phase are investigated under 2 MeV Au ion bombardment at 160 and 400 K to doses up to 35 displacements per atom (dpa). The NSZ films are produced by ion-beam-assisted deposition technique at room temperature with an average grain size of 7.7 nm. The grain size increases with dose, and follows a power law (n=6) to a saturation value of ~30 nm that decreases with temperature. Slower grain growth is observed under 400 K irradiations, as compared to 160 K irradiations, indicating that thermal grain growth is not activated and defect-stimulated grain growth is the dominating mechanism. While cubic phase is perfectly retained and no new phases are identified after the high-dose irradiations, reduction of oxygen in the irradiated NSZ films is detected. The ratio of O to Zr decreases from ~2.0 for the as-deposited films to ~1.65 after irradiation to ~35 dpa. Significant increase of oxygen vacancies in nanocrystalline zirconia suggests substantially enhanced oxygen diffusion under ion irradiation, a materials behavior far from equilibrium. The oxygen deficiency may be essential in stabilizing cubic phase to larger grain sizes.

Zhang, Yanwen; Jiang, Weilin; Wang, Chong M.; Namavar, Fereydoon; Edmondson, Philip D.; Zhu, Zihua; Gao, Fei; Lian, Jie; Weber, William J.

2010-11-10

406

Effect of low energy ion beam irradiation on wettability of narra (Pterocarpus indicus) wood chips  

NASA Astrophysics Data System (ADS)

Narra (Pterocarpus indicus) wood chips were irradiated with positive hydrogen ions H+ and H2+ to make them hydrophobic. The ions were produced and extracted from a gas discharge ion source. The extracted beam current ranges from 0.01 to 0.07 ?A for discharge currents of 1.0 4.0 mA, discharge potential between 600 V and 1000 V. The chips, positioned at 70 mm downstream from the ion source, were processed for different time periods and discharge currents. The wettability was characterized by the contact angle of the liquid droplet with respect to the wood surface. Surface modifications were assessed with by measurements of the water contact angle. Tests indicate retarded absorption characteristics for ion-irradiated samples compared to controlled samples. The longest absorptive inhibition were exhibited by samples irradiated for 30 min, at discharge current of 1.0 mA, 720 eV ion energy and 0 V extraction potential. Scanning electron micrographs reveal the difference in morphologies of treated and untreated samples. The results prove that low energy beams of hydrogen from a gas discharge ion source are suitable in transforming surfaces of wood chips to be water resistant.

Ramos, Henry J.; Monasterial, Jonathan Lee C.; Blantocas, Gene Q.

2006-01-01

407

Damage and helium migration induced in fluorapatite sinters by swift heavy ion irradiations  

NASA Astrophysics Data System (ADS)

We have studied the damage induced in fluorapatite (Ca10(PO4)6F2) sinters after 70-MeV Kr, 120 MeV I and 163-MeV Au ion irradiations at room temperature. On the basis of X-ray powder diffraction data we conclude that fluorapatite is not completely amorphized due to ion-induced recrystallization. This recrystallization of the amorphous phase is greatly enhanced for Au ions with a high electronic stopping power. We also have used the 3He(d, p) 4He nuclear reaction to study the migration of implanted 3-MeV 3He ions after swift heavy ion irradiations. The proton yield curves versus deuteron energy for irradiated samples exhibit two bumps for high fluences. These excitation curves are deconvoluted by using a computer code based on a two-diffusion equation model of helium atoms in two accumulation zones. Optimizations of the model parameters give access to the diffusion coefficients and helium depth profiles in the two zones. This yields two broad peaks in the helium depth profiles, the first one is near the end-of-range region and the second one is shifted at about half way between the surface and the first peak. This shift is interpreted as a Radiation-Enhanced Diffusion (RED) effect which is found to increase with fluence for Kr ions, and with electronic stopping power from Kr to Au ions.

Miro, S.; Costantini, J. M.; Haussy, J.; Chateigner, D.; Balanzat, E.

2012-04-01

408

Effect of swift heavy ion irradiation on bare and coated ZnS quantum dots  

SciTech Connect

The present study compares structural and optical modifications of bare and silica (SiO{sub 2}) coated ZnS quantum dots under swift heavy ion (SHI) irradiation. Bare and silica coated ZnS quantum dots were prepared following an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. X-ray diffraction (XRD) and transmission electron microscopy (TEM) study of the samples show the formation of almost spherical ZnS quantum dots. The UV-Vis absorption spectra reveal blue shift relative to bulk material in absorption energy while photoluminescence (PL) spectra suggests that surface state and near band edge emissions are dominating in case of bare and coated samples, respectively. Swift heavy ion irradiation of the samples was carried out with 160 MeV Ni{sup 12+} ion beam with fluences 10{sup 12} to 10{sup 13} ions/cm{sup 2}. Size enhancement of bare quantum dots after irradiation has been indicated in XRD and TEM analysis of the samples which has also been supported by optical absorption spectra. However similar investigations on irradiated coated quantum dots revealed little change in quantum dot size and emission. The present study thus shows that the coated ZnS quantum dots are stable upon SHI irradiation compared to the bare one.

Chowdhury, S. [Department of Physics, Gauhati University, Guwahati, Assam 781014 (India)], E-mail: sky@tezu.ernet.in; Hussain, A.M.P. [Department of Physics, Gauhati University, Guwahati, Assam 781014 (India); Ahmed, G.A. [Department of Physics, Tezpur University, Napaam, Tezpur, Assam 784028 (India); Singh, F.; Avasthi, D.K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Choudhury, A. [Department of Physics, Tezpur University, Napaam, Tezpur, Assam 784028 (India)

2008-12-01

409

Enhancement of ferromagnetism in Pd nanoparticle by swift heavy ion irradiation  

SciTech Connect

In this study, the effect of swift heavy ion irradiation on the magnetic properties of the Pd nanoparticles has been investigated. Structural investigations along with superconducting quantum interface device measurements show that ferromagnetic properties of the Pd nanoparticles are due to the deviation of their electronic structure from that of bulk. The electronic structure is further modified due to the creation of defects on ion irradiation, which results in 20 times increase in the saturation magnetization. The present study establishes that the defect induced modification of Pd 4d electronic structure is responsible for the ferromagnetic properties of the Pd nanoparticles.

Kulriya, P. K. [Department of Physics, Thin Film Laboratory, Indian Institute of Technology, New Delhi 110 016 (India); Inter-University Accelerator Centre, Aruna Asaf Ali Road, New Delhi 110067 (India); Mehta, B. R. [Department of Physics, Thin Film Laboratory, Indian Institute of Technology, New Delhi 110 016 (India); Avasthi, D. K.; Agarwal, D. C. [Inter-University Accelerator Centre, Aruna Asaf Ali Road, New Delhi 110067 (India); Thakur, P.; Brookes, N. B. [European Synchrotron Radiation Facility (ESRF), BP 220, F-38043 Grenoble Cedex (France); Chawla, A. K.; Chandra, R. [Nanoscience Laboratory, Institute Instrumentation Centre, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

2010-02-01

410

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

411

Fabricating high-density magnetic storage elements by low-dose ion beam irradiation  

SciTech Connect

We fabricate magnetic storage elements by irradiating an antiferromagnetically coupled ferromagnetic/nonmagnetic/ferromagnetic trilayer by a low-dose ion beam. The irradiated areas become ferromagnetically coupled and are capable of storing information if their size is small enough. We employ Fe/Cr/Fe trilayers and a 30 keV focused Ga{sup +}-ion beam to demonstrate the working principle for a storage array with a bit density of 7 Gbit/in.{sup 2}. Micromagnetic simulations suggest that bit densities of at least two magnitudes of order larger should be possible.

Neb, R.; Sebastian, T.; Pirro, P.; Hillebrands, B. [Fachbereich Physik and Research Center Optimas, Technische Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse 56, 67663 Kaiserslautern (Germany); Pofahl, S.; Schaefer, R. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung Dresden, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany); Reuscher, B. [Institut fuer Oberflaechen-und Schichtanalytik, IFOS, Trippstadter Strasse 120, 67663 Kaiserslautern (Germany)

2012-09-10

412

Grain growth kinetics during ion beam irradiation of chemical vapor deposited amorphous silicon  

SciTech Connect

The amorphous to polycrystal transition during Kr ion beam irradiation of chemical vapor deposited silicon layers has been studied in the temperature range 320--480 {degree}C. At each irradiation temperature the average grain diameter increases linearly with the Kr dose, while the grain density remains constant within the experimental accuracy. The growth rate follows a complex behavior which can be described by dynamic defect generation and annihilation. The absolute value of the grain growth rate is equal to that of the ion-assisted epitaxial layer by layer crystallization in the silicon (111) orientation. This result can be related to the crystal grain structure and morphology.

Spinella, C.; Lombardo, S. (Istituto di Metodologie e Tecnologie per la Microelettronica, CNR, corso Italia 57, I 95129 Catania (Italy)); Campisano, S.U. (Dipartimento di Fisica dell'Universita, corso Italia 57, I 95129 Catania (Italy))

1990-08-06

413

Combined high pressure and heavy-ion irradiation: a novel approach.  

PubMed

Swift heavy-ion irradiations of a wide variety of materials have been used to modify and manipulate the properties of solids at the nanoscale. Recently, these high-energy irradiations have been successfully combined with high-pressure experiments. Based on results obtained for zircon (ZrSiO(4)), this paper introduces this new experimental approach involving diamond anvil cells and large ion-accelerator facilities. This technique provides a wide spectrum of geoscience applications from nanoscale simulations of fission-track formation under crustal conditions to phase transitions of radiation-damaged minerals resulting from meteorite impact. PMID:19844013

Lang, Maik; Zhang, Fuxiang; Lian, Jie; Trautmann, Christina; Neumann, Reinhard; Ewing, Rodney C

2009-09-12

414

Comparison of superconducting flux pinning due to ion irradiation and fishtail effects  

SciTech Connect

Heavy-ion irradiation experiments have been carried out for single crystals of YBa{sub 2}Cu{sub 4}O{sub 8} in order to compare the magnetic-field dependence of the flux pinning for damage channels with the intrinsic {open_quote}{open_quote}fishtail{close_quote}{close_quote} pinning that occurs in this material before irradiation. The two pinning effects seem to be additive in that irradiation increases the hysteresis at all fields and the fishtail hump persists in the irradiated samples with roughly the same magnitude as before the damage channels are produced. For irradiated samples, there are two regions where pinning rises with increasing field, one near zero field due to a matching effect of the defect density with the vortex lattice spacing and a second at the same field as the original fishtail. Both effects appear in the same sample in different magnetic-field ranges. {copyright} {ital 1996 The American Physical Society.}

Xu, M.; Ostenson, J.E.; Finnemore, D.K.; Kramer, M.J. [Ames Laboratory, United States Department of Energy and Department of Physics, Iowa State University, Ames, Iowa 50011 (United States); Fendrich, J.A.; Hettinger, J.D.; Welp, U.; Crabtree, G.W. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Dabrowski, B. [Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States); Zhang, K. [James Frank Institute, University of Chicago, Chicago, Illinois 60637 (United States)

1996-03-01

415

Comparison of superconducting flux pinning due to ion irradiation and fishtail effects  

NASA Astrophysics Data System (ADS)

Heavy-ion irradiation experiments have been carried out for single crystals of YBa2Cu4O8 in order to compare the magnetic-field dependence of the flux pinning for damage channels with the intrinsic ``fishtail'' pinning that occurs in this material before irradiation. The two pinning effects seem to be additive in that irradiation increases the hysteresis at all fields and the fishtail hump persists in the irradiated samples with roughly the same magnitude as before the damage channels are produced. For irradiated samples, there are two regions where pinning rises with increasing field, one near zero field due to a matching effect of the defect density with the vortex lattice spacing and a second at the same field as the original fishtail. Both effects appear in the same sample in different magnetic-field ranges.

Xu, Ming; Ostenson, J. E.; Finnemore, D. K.; Kramer, M. J.; Fendrich, J. A.; Hettinger, J. D.; Welp, U.; Crabtree, G. W.; Dabrowski, B.; Zhang, K.

1996-03-01

416

Activated Ion Electron Capture Dissociation (AI ECD) of Proteins: Synchronization of Infrared and Electron Irradiation with Ion Magnetron Motion  

PubMed Central

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 CO2 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.

Mikhailov, Victor A.; Cooper, Helen J.

2009-01-01

417

A comparative study of argon ion irradiated pristine and fluorinated single-wall carbon nanotubes  

SciTech Connect

Effect of Ar{sup +} ion irradiation on the structure of pristine and fluorinated single-wall carbon nanotubes (SWCNTs) was examined using transmission electron microscopy (TEM), Raman, and x-ray photoelectron spectroscopy (XPS). The TEM analysis revealed retention of tubular structures in both irradiated samples while Raman spectroscopy and XPS data indicated a partial destruction of nanotubes and formation of oxygen-containing groups on the nanotube surface. From similarity of electronic states of carbon in the irradiated pristine and fluorinated SWCNTs observed by XPS, it was suggested that defluorination of nanotubes proceeded with breaking of C-F bonds.

Fedoseeva, Yu. V.; Bulusheva, L. G.; Okotrub, A. V. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk (Russian Federation); Vyalikh, D. V. [Institute of Solid State Physics, Dresden University of Technology, D-01062 Dresden (Germany); Fonseca, A. [NANOPART N.V., Kapeldreef 60, B-3001 Leuven (Belgium)

2010-12-14

418

Energy deposition and fragments production resulting from gamma-ray or ion beam irradiation of an ion exchange resin  

NASA Astrophysics Data System (ADS)

The extraction efficiency of ion exchange resins aimed at the reprocessing of nuclear effluents is strongly dependent on gamma-ray induced modifications of their chemical structure. A poly(4-vinylpyridine) resin, or P4VP, has been subjected to gamma irradiation using a 137Cs source (E[gamma] = 662 keV) and we have attempted to characterize its structural modifications using TOF-SIMS techniques based on low (keV) and high (MeV) primary ion beam energies. These analytical techniques are based on the formation of fragments resulting respectively from atomic and electronic collisions of heavy ions. As a result, the differences in nature and relative intensity of the emitted secondary ions, as well as the variation of their intensity as a function of the absorbed dose of gamma rays (up to 14 400 kGy), can be interpreted from different types of bond breaking. While gamma-ray absorption results in benzylic or pyridinic scissions, MeV ion bombardment may induce simultaneous (and close) pyridinic-pyridinic or pyridinic-benzylic scissions, or both. Accordingly, the technique is very sensitive to the presence of fragments preformed under gamma irradiation. This is not observed with keV bombardment which may destroy the pyridine nucleus. The SIMS analysis of the soluble fraction of the irradiated material (free radicals and fragments) and of the remaining material confirms the proposed fragmentation paths leading to positive and negative ion emission. Such results fully support the important finding that these gamma-ray induced modifications are only observed from negative emission under MeV ion bombardment.

Nsouli, B.; Draye, M.; Allali, H.; Lemaire, M.; Thomas, J.-P.

1996-07-01

419

Effect of titanium ion irradiation on the surface and defect centre formation in sapphire  

NASA Astrophysics Data System (ADS)

Swift titanium ion irradiation was carried out on sapphire (Al2O3: Fe, Ti, Cr) to study optical properties of defect centers and surface topography of modified sapphire using UV visible absorption spectroscopy, photoluminescence (PL) and atomic force microscopy (AFM) techniques. Single crystals of sapphire were irradiated at room temperature with different fluence of 100 MeV Ti ions. The PL spectra showed three emission bands centred at 2.56 (480 nm), 2.45 (504 nm) and 2.31 eV (535 nm) assigned to F+ centre, F2 centre and F22+ defect centre, respectively. The intensity of these bands was found to change with fluence. R lines of Cr3+ ion impurity, though weak in pristine sample, grew tremendously on ion irradiation. The changes in the intensity of R lines are correlated with the Cr3+-defect centre pair formation. Both bands and lines showed downward trend at higher fluence but at a different fluence value. Results are interpreted in terms of creation of defect centres, aggregation/cluster formation, diffusion or radiation induced annihilation of the defects. The defect centres (F2+ and F22+) and R-line of Cr3+ ions were observed in optical spectra and their behaviour upon irradiation is also discussed in terms of dense ionization. The behaviour of bands corresponding to the electronic transitions of Fe2+/Ti4+ ions in the presence of oxygen vacancies, observed in optical spectra, are discussed in terms of dense ionization. The hillocks like structures were developed on the surface of irradiated sapphires. Their concentration, height and area are correlated with the ion beam fluence.

Jheeta, K. S.; Jain, D. C.; Ravi Kumar; Garg, K. B.

2007-12-01

420

Damage profiles and ion distribution in Pt-irradiated SiC  

NASA Astrophysics Data System (ADS)

Single crystalline 6H-SiC samples were irradiated at 150 K with 2 MeV Pt ions. The local volume swelling was determined by electron energy loss spectroscopy (EELS), and a nearly sigmoidal dependence on irradiation dose is observed. The disorder profiles and ion distribution were determined by Rutherford backscattering spectrometry (RBS), transmission electron microscopy, and secondary ion mass spectrometry. Since the volume swelling reaches 12% over the damage region at high ion fluence, the effect of lattice expansion is considered and corrected for in the analysis of RBS spectra to obtain depth profiles. Projectile and damage profiles are estimated by SRIM (Stopping and Range of Ions in Matter). When compared with the measured profiles, the SRIM code predictions of ion distribution and the damage profiles are underestimated due to significant overestimation of the electronic stopping power for the slow heavy Pt ions. By utilizing the reciprocity method, which is based on the invariance of the inelastic energy loss in ion-solid collisions against interchange of projectile and target atom, a much lower electronic stopping power is deduced. A simple approach, based on reducing the density of SiC target in SRIM simulation, is proposed to compensate the overestimated SRIM electronic stopping power values, which results in improved agreement between predicted and measured damage profiles and ion ranges.

Xue, H. Z.; Zhang, Y.; Zhu, Z.; Zhang, W. M.; Bae, I.-T.; Weber, W. J.

2012-09-01