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Sample records for light ion irradiation

  1. Light ion irradiation for unfavorable soft tissue sarcoma

    SciTech Connect

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

    1990-09-01

    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.

  2. Enhanced light absorption of amorphous silicon thin film by substrate control and ion irradiation

    PubMed Central

    2014-01-01

    Large-area periodically aligned silicon nanopillar (PASiNP) arrays were fabricated by magnetic sputtering with glancing angle deposition (GLAD) on substrates coated by a monolayer of close-packed polystyrene (PS) nanospheres. The structure of PASiNP arrays could be manipulated by changing the diameter of PS nanospheres. Enhanced light absorptance within a wavelength range from 300 to 1,000 nm was observed as the diameter of nanopillars and porosity of PASiNP arrays increased. Meanwhile, Xe ion irradiation with dose from 1 × 1014 to 50 × 1014 ions/cm2 was employed to modify the surface morphology and top structure of thin films, and the effect of the irradiation on the optical bandgap was discussed. PACS code 81.15.Cd; 78.66.Jg; 61.80.Jh PMID:24717078

  3. SiO2 Etching Yield Measurements by CF3 Ion Beam Injections Superposed with Light Irradiation

    NASA Astrophysics Data System (ADS)

    Ikuse, Kazumasa; Yoshimura, Satoru; Takizawa, Toshifumi; Karahashi, Kazuhiro; Kiuchi, Masato; Hamaguchi, Satoshi

    Etching yields of SiO2 by CF3 ion beam injections with or without simultaneous light irradiation have been measured by a low-energy mass-selected ion beam system. A Xe Lamp, an L2D2 lamp, an Ar ICP (inductively coupled plasma) or a VUV (Vacuum Ultraviolet) Lamp was used separately as the light source. The etching yield is the ratio of the number of incident ions to that of removed atoms. The obtained SiO2 etching yields by simultaneous irradiation of CF3 ions and photons from the light source were smaller than those by ion beam irradiation only. This difference in etching yields may be caused by modification of CFx polymer formation on the substrate surface during the beam etching process.

  4. Resonant absorption effects induced by polarized laser light irradiating thin foils in the TNSA regime of ion acceleration

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Badziak, J.; Rosinski, M.; Zaras-Szydlowska, A.; Pfeifer, M.; Torrisi, A.

    2016-04-01

    Thin foils were irradiated by short pulsed lasers at intensities of 1016-19W/cm2 in order to produce non-equilibrium plasmas and ion acceleration from the target-normal-sheath-acceleration (TNSA) regime. Ion acceleration in forward direction was measured by SiC detectors and ion collectors used in the time-of-flight configuration. Laser irradiations were employed using p-polarized light at different incidence angles with respect to the target surface and at different focal distances from the target surface. Measurements demonstrate that resonant absorption effects, due to the plasma wave excitations, enhance the plasma temperature and the ion acceleration with respect to those performed without to use of p-polarized light. Dependences of the ion flux characteristics on the laser energy, wavelength, focal distance and incidence angle will be reported and discussed.

  5. Heavy and light ion irradiation damage effects in δ-phase Sc4Hf3O12

    NASA Astrophysics Data System (ADS)

    Wen, J.; Li, Y. H.; Tang, M.; Valdez, J. A.; Wang, Y. Q.; Patel, M. K.; Sickafus, K. E.

    2015-12-01

    Polycrystalline δ-phase Sc4Hf3O12 was irradiated with light and heavy ions to study the radiation stability of this compound. In order to explore the ion species spectrum effect, the irradiations were performed with 400 keV Ne2+ ions to fluences ranging from 1 × 1014 to 1 × 1015 ions/cm2, 600 keV Kr3+ ions to fluences ranging from 5 × 1014 to 5 × 1015 ions/cm2, and 6 MeV Xe26+ ions to fluences ranging from 2 × 1013 to 1 × 1015 ions/cm2. Irradiated samples were characterized by various techniques including grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). A complete phase transformation from ordered rhombohedral to disordered fluorite was observed by a fluence of 1 × 1015 ions/cm2 with 400 keV Ne2+ ions, equivalent to a peak ballistic damage dose of ∼0.33 displacements per atom (dpa). Meanwhile, the same transformation was also observed by 600 keV Kr3+ ions at the same fluence of 1 × 1015 ions/cm2, which however corresponds to a peak ballistic damage dose of ∼2.2 dpa. Only a partial O-D transformation was observed for 6 MeV Xe26+ ions in the fluence range used. Experimental results indicated that the O-D transformation is observed under both electronic and nuclear stopping dominant irradiation regimes. It was also observed that light ions are more efficient than heavy ions in producing the retained defects that are presumably responsible for the O-D phase transformation. The O-D transformation mechanism is discussed in the context of anion oxygen Frenkel defects and cation antisite defects. We concluded that the irradiation induced O-D transformation is easier to occur in δ-phase compounds with partial order of cations than in that with fully disordered cation structures.

  6. Defect engineering in GaAs using high energy light ion irradiation: Role of electronic energy loss

    SciTech Connect

    Kabiraj, D.; Ghosh, Subhasis

    2011-02-01

    We report on the application of high energy light ions (Li and O) irradiation for modification of defects, in particular, for annihilation of point defects using electronic energy loss in GaAs to minimize the defects produced by nuclear collisions. The high resolution x-ray diffraction and micro-Raman spectroscopy have been used to monitor that no lattice damage or amorphization take place due to irradiating ions. The effects of irradiation on defects and their energy levels have been studied using thermally stimulated current spectroscopy. It has been observed that till an optimum irradiation fluence of 10{sup 13} ions/cm{sup 2} there is annihilation of native defects but further increase in irradiation fluence results in accumulation of defects, which scales with the nuclear energy loss process, indicating that the rate of defects produced by the binary collision process exceeds rate of defect annihilation. Defect annihilation due to electronic energy loss has been discussed on the basis of breaking of bonds and enhanced diffusivity of ionized native defects.

  7. Modifications of EL2 related stable and metastable defects in semi-insulating GaAs by high energy light ion irradiation

    NASA Astrophysics Data System (ADS)

    Kabiraj, D.; Ghosh, S.

    2005-10-01

    We report the effect of high energy light ion irradiation on the defect energy levels related to the stable and metastable states of EL2 in undoped semi-insulating GaAs. GaAs samples have been irradiated at different fluences with 50 MeV Li ions. The energy of the irradiated ions is chosen in such a way that the range of the ions is more than the sample thickness. So the implantation of the irradiated ions and the formation of the extended defects at the end of the range could be avoided. The modification of the existing native point defects and the formation of new point defects under irradiation have been studied by photocurrent and thermally stimulated current spectroscopic measurements under the photoexcitation of both sub-band gap and above band gap lights.

  8. Enhanced inactivation of E. coli and MS-2 phage by silver ions combined with UV-A and visible light irradiation.

    PubMed

    Kim, Jee Yeon; Lee, Changha; Cho, Min; Yoon, Jeyong

    2008-01-01

    Silver ions have been widely used as an effective water disinfectant or antimicrobial material for many decades. In addition, the application of silver ions in combination with other biocides, especially UV(254) (UV-C) irradiation, was reported to be effective in enhancing its germicidal activity. However, it is not yet known how UV-A (300-400 nm) or visible light irradiation, which have little or no antimicrobial activities, affect microorganism inactivation by silver ions. This study newly reports that the inactivation efficiencies of Escherichia coli and MS-2 phage by silver ions were significantly enhanced by UV-A or visible light irradiation. UV-A irradiation enhanced the inactivation of E. coli and MS-2 phage by 3.0 and 2.5 log/30 min, respectively, as compared with the simple summated value of individual applications of silver ions and UV-A. A similar trend was observed with visible light irradiation (>400 nm) although the level of enhancement was lessened. The photochemical reaction of silver-cysteine complex was suggested as a possible mechanism for this enhancement. Spectrophotometric and MALDI-TOF mass analyses support the fact that silver ions coupled with light irradiation causes critical cell damage through the complexation of silver ions with thiol (-SH) groups in structural or enzymatic proteins of the microorganisms and their subsequent photochemical destruction.

  9. Secondary absorbed doses from light ion irradiation in anthropomorphic phantoms representing an adult male and a 10 year old child

    NASA Astrophysics Data System (ADS)

    Hultqvist, Martha; Gudowska, Irena

    2010-11-01

    Secondary organ absorbed doses were calculated by Monte Carlo simulations with the SHIELD-HIT07 code coupled with the mathematical anthropomorphic phantoms CHILD-HIT and ADAM-HIT. The simulated irradiations were performed with primary 1H, 4He, 7Li, 12C and 16O ion beams in the energy range 100-400 MeV/u which were directly impinging on the phantoms, i.e. approximating scanned beams, and with a simplified beamline for 12C irradiation. The evaluated absorbed doses to the out-of-field organs were in the range 10-6 to 10-1 mGy per target Gy and with standard deviations 0.5-20%. While the contribution to the organ absorbed doses from secondary neutrons dominated in the ion beams of low atomic number Z, the produced charged fragments and their subsequent charged secondaries of higher generations became increasingly important for the secondary dose delivery as Z of the primary ions increased. As compared to the simulated scanned 12C ion beam, the implementation of a simplified beamline for prostate irradiation with 12C ions resulted in an increase of 2-50 times in the organ absorbed doses depending on the distance from the target volume. Comparison of secondary organ absorbed doses delivered by 1H and 12C beams showed smaller differences when the RBE for local tumor control of the ions was considered and normalization to the RBE-weighted dose to the target was performed.

  10. Ultrasonic synthesis and photocatalytic performance of metal-ions doped TiO{sub 2} catalysts under solar light irradiation

    SciTech Connect

    Feng, Huajun; Yu, Liya E.; Zhang, Min-Hong

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► We synthesized eight metal-ions doped TiO{sub 2} catalysts by a unique ultrasonic method. ► Mg-doped TiO{sub 2} showed the highest photocatalytic performance under solar light. ► Surface area of catalyst dominates the photocatalytic efficiency under solar light. ► Crystal property and visible light activity are less important than surface area. -- Abstract: Eight metal-ions doped TiO{sub 2} (M-TiO{sub 2}) were successfully synthesized by an ultrasonic method, including Fe, Co, Ce, Cr, Mn, Mg, Ni and Ag ions. Among them, the 1% Mg–TiO{sub 2} shows the highest photocatalytic efficiency under solar light, which was determined by degrading rhodamine B (RhB) molecules in an aqueous solution. The synthesized M-TiO{sub 2} samples were characterized by XRD, BET Surface area, TEM, XPS and diffuse reflectance spectrum. Effects of synthesis conditions and characterized properties on photocatalytic efficiency of the M-TiO{sub 2} were investigated comprehensively. A positive correlation between specific surface area and photocatalytic efficiency of the M-TiO{sub 2} was found across different synthesis conditions. However, no clear correlation with photocatalytic efficiency was observed for crystal structure and radii of doping ions of the M-TiO{sub 2}. XPS study indicates the change of oxidation states of Mn ions in Mn–TiO{sub 2} during synthesis procedure from the initial Mn{sup 2+} to a mixture of Mn{sup 3+} and Mn{sup 4+} ions. Dye sensitization mechanism was observed during the photocatalytic procedure of the Mg–TiO{sub 2}, which enhanced the degradation efficiency of the Mg–TiO{sub 2} under solar light. Finally, no obvious loss of photocatalytic activity was observed for the Mg–TiO{sub 2} after five cycles of RhB degradation.

  11. Measurement of activation of rhodopsine with heavy ions irradiation in the ALTEA program: a possible mechanism responsible for light flash perceptions in space

    NASA Astrophysics Data System (ADS)

    Narici, Livio; Rinaldi, Adele; Sannita, Walter, , Prof; Paci, Maurizio; Brunetti, Valentina; de Martino, Angelo; Picozza, Piergiorgio

    Since late 60s astronauts in space have reported seeing flashes of light, more frequently when dark adapted. Experiments have been performed to characterize these phenomena, and to suggest possible mechanisms. High Z ions have been shown to be the most likely cause of these perceptions: when ionizing radiation hits the eye there is a high probability of a light flash perception. However the mechanisms behind this phenomenon are not fully understood yet. We show that one of these mechanisms is the activation of the rhodopsin (bleaching) by heavy ions. Rhodopsin is at the start of the photo-electronic cascade in the process of vision. It is one of the best molecular transducer to convert a visible photon into an electric signal. In this work we show that rhodopsine can also be activated by irradiation with 12C nuclei. In the frame of ALTEA program, aimed at studying the effects of cosmic radiation on brain functions, an investigation on the interaction between heavy ions and rhodopsin has been performed. Intact Rod Outer Segment (ROS) containing rhodopsin were isolated from bovine retina. Suspended rods were irradiated with 12C (200 MeV/n, well below the Cherenkov threshold) at GSI (Darmstadt FRG) with doses ranging from few mrem to several rem. Spectrophotometric measurements investigated the presence of non activated and activated rhodopsin. The functionality of the purified rods were checked by previous light irradiation and subsequent regeneration by the addition of external 11-cis-retinal, to confirm the reversibility of the process in vitro. We can show effective and reversible bleaching also following irradiation, thus proving that the rhodopsin was not damaged by radiation. Works are in progress to model this interaction. Latest analysis results and considerations about the underlying mechanism will be presented.

  12. Influence of ageing on Raman spectra and the conductivity of monolayer graphene samples irradiated by heavy and light ions

    NASA Astrophysics Data System (ADS)

    Butenko, A.; Zion, E.; Kaganovskii, Yu.; Wolfson, L.; Richter, V.; Sharoni, A.; Kogan, E.; Kaveh, M.; Shlimak, I.

    2016-07-01

    The influence of long-term ageing (about one year) on the Raman scattering (RS) spectra and the temperature dependence of conductivity has been studied in two series of monolayer graphene samples irradiated by different doses of C+ and Xe+ ions. It is shown that the main result of ageing consists of changes in the intensity and position of D- and G- and 2D-lines in RS spectra and in an increase of the conductivity. The observed effects are explained in terms of an increase of the radius of the "activated" area around structural defects.

  13. Influence of ageing on Raman spectra and the conductivity of monolayer graphene samples irradiated by heavy and light ions

    SciTech Connect

    Butenko, A.; Zion, E.; Richter, V.; Sharoni, A.; Kaganovskii, Yu.; Wolfson, L.; Kogan, E.; Kaveh, M.; Shlimak, I.

    2016-07-28

    The influence of long-term ageing (about one year) on the Raman scattering (RS) spectra and the temperature dependence of conductivity has been studied in two series of monolayer graphene samples irradiated by different doses of C{sup +} and Xe{sup +} ions. It is shown that the main result of ageing consists of changes in the intensity and position of D- and G- and 2D-lines in RS spectra and in an increase of the conductivity. The observed effects are explained in terms of an increase of the radius of the “activated” area around structural defects.

  14. An extended formula for the energy spectrum of sputtered atoms from a material irradiated by light ions

    NASA Astrophysics Data System (ADS)

    Ono, T.; Aoki, Y.; Kawamura, T.; Kenmotsu, T.; Yamamura, Y.

    2005-03-01

    We extend a formula proposed by Kenmotsu et al. (hereafter Paper I), which fits with the energy spectrum of atoms sputtered from a heavy material hit by low-energy light ions (H +, D +, T +, He +) by taking into account an inelastic energy loss neglected in Paper I. We assume that primary knock-on atoms produced by ions backscattered at large angles do not lose energy while penetrating the material up to the surface, instead of the energy-loss model used in Paper I. The extended formula is expressed in terms of a normalized energy-distribution function and is compared with the data calculated with the ACAT code for 50 eV, 100 eV and 1 keV D + ions impinging on a Fe target. Our formula fits well with the data in a wide range of incident energy.

  15. Deformation behavior of ion-irradiated polyimide

    SciTech Connect

    Kucheyev, S.O.; Felter, T.E.; Anthamatten, M.; Bradby, J.E.

    2004-08-02

    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.

  16. The light ion trough.

    NASA Technical Reports Server (NTRS)

    Taylor, H. A., Jr.

    1972-01-01

    A distinct feature of the ion composition results from the OGO-2, 4 and 6 satellites is the light ion trough, wherein the mid-latitude concentrations of H+ and He+ decrease sharply with latitude. In contrast to the 'main trough' in electron density observed primarily as a nightside phenomenon, the light ion trough persists during both day and night. For daytime winter hemisphere conditions and for all seasons during night, the mid-latitude light ion concentration decrease is a pronounced feature. In the dayside summer and equinox hemispheres, the rate of light ion decrease with latitude is comparatively gradual, and the trough boundary is less well defined, particularly for quiet magnetic conditions. In response to magnetic storms, the light ion trough minimum moves equatorward, and deepens, consistent with earlier evidence of the contraction of the plasmasphere in response to storm time enhancements in magnetospheric plasma convection.

  17. Tuning of the optical properties of In-rich In{sub x}Ga{sub 1−x}N (x=0.82−0.49) alloys by light-ion irradiation at low energy

    SciTech Connect

    De Luca, Marta; Polimeni, Antonio; Capizzi, Mario; Pettinari, Giorgio; Ciatto, Gianluca; Fonda, Emiliano; Amidani, Lucia; Boscherini, Federico; Knübel, Andreas; Cimalla, Volker; Ambacher, Oliver; Giubertoni, Damiano; Bersani, Massimo

    2013-12-04

    The effects of low-energy irradiation by light ions (H and He) on the properties of In-rich In{sub x}Ga{sub 1−x}N alloys are investigated by optical and structural techniques. H-irradiation gives rise to a remarkable blue-shift of light emission and absorption edge energies. X-ray absorption measurements and first-principle calculations address the microscopic origin of these effects.

  18. Ion irradiation of astrophysical ices

    NASA Astrophysics Data System (ADS)

    Palumbo, M. E.; Baratta, G. A.; Fulvio, D.; Garozzo, M.; Gomis, O.; Leto, G.; Spinella, F.; Strazzulla, G.

    2008-02-01

    Ices, silicates and carbonaceous materials have been detected in several astrophysical environments such as interstellar molecular clouds, comets, and planetary surfaces. These solids are continuously exposed to ion irradiation and UV photolysis. Our knowledge on the properties of solids and molecules and on the modification induced by fast ions (keV-MeV) and UV photons is mainly based on laboratory experiments and on the comparison of experimental results with observations. Here we will give a few examples of the role of laboratory experiments to our understanding of the physical and chemical properties of ices in space.

  19. 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

    Kachurin, G. A. Cherkova, S. G.; Marin, D. V.; Kesler, V. G.; Skuratov, V. A.; Cherkov, A. G.

    2011-03-15

    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.

  20. Emulation of reactor irradiation damage using ion beams

    DOE PAGES

    Was, G. S.; Jiao, Z.; Getto, E.; ...

    2014-06-14

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

  1. Emulation of reactor irradiation damage using ion beams

    SciTech Connect

    Was, G. S.; Jiao, Z.; Getto, E.; Sun, K.; Monterrosa, A. M.; Maloy, S. A.; Anderoglu, O.; Sencer, B. H.; Hackett, M.

    2014-06-14

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

  2. Systematic Modification of Electrical and Superconducting Properties of YBCO and Nano-Patterning of High-Tc Superconducting Thin Films by Light-Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Pedarnig, J. D.; Bodea, M. A.; Steiger, B.; Markowitsch, W.; Lang, W.

    Irradiation of high-temperature superconducting (HTS) YBa2Cu3O7-d (YBCO) thin films with 75 keV He+ ions leads to a quasi-exponential increase of the in-plane (ρab) and the out-of-plane (ρc) resistivity in the normal state and to a non-linear decrease of the critical temperature Tc with ion dose. In situ electrical measurements at room temperature reveal an irradiation-induced reduction of resistivity anisotropy ρc/ρab and a slight relaxation of film resistivity after the ion irradiation is stopped. Ex situ measurements show a stretched-exponential relaxation of Tc and normal state resistivity that continues for several weeks after the ion irradiation. Irradiation of YBCO thin films by low-energy He+ ions through stencil masks results in local modification of the electrical and superconducting properties of the HTS material. We demonstrate that masked ion-beam lithography enables to produce structures smaller than 100 nm in size that have potential for applications in future superconducting nano-electronics.

  3. Photochemical Activity of Uranyl Ion in Acetone Irradiated by Light in the Presence of Metal Cations and Anions

    NASA Astrophysics Data System (ADS)

    Umreiko, D. S.; Vileishikova, N. P.; Zajogin, A. P.; Komyak, A. I.

    2015-11-01

    The effects of several metal cations and anions on complexation of tetra- and pentavalent uranium in an acetone solution of UO2(ClO4)2·5H2O irradiated by an LED (420-440 nm) were studied using electronic absorption. It was shown that addition of background components to the solution had an insignificant effect on complexation of the lowest-valent uranium. The composition of the UO 2 2 + coordination sphere could change at a certain irradiation time (>90 min) but the system as a whole was maintained.

  4. Enhanced electrochemical etching of ion irradiated silicon by localized amorphization

    SciTech Connect

    Dang, Z. Y.; Breese, M. B. H.; Lin, Y.; Tok, E. S.; Vittone, E.

    2014-05-12

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

  5. Spectrometry of the Rutherford backscattering of ions and the Raman scattering of light in GaS single crystals irradiated with 140-keV H{sub 2}{sup +} ions

    SciTech Connect

    Garibov, A. A.; Madatov, R. S.; Komarov, F. F.; Pilko, V. V.; Mustafayev, Yu. M.; Akhmedov, F. I.; Jakhangirov, M. M.

    2015-05-15

    The methods of the Raman scattering of light and Rutherford backscattering are used to study the degree of structural disorder in layered GaS crystals before and after irradiation with 140-keV H{sub 2}{sup +} ions. It is shown that the distribution of the crystal’s components over depth is homogeneous; for doses as high as 5 × 10{sup 15} cm{sup −2}, the stoichiometric composition of the compound’s components is retained. The experimental value of the critical dose for the beginning of amorphization amounts to about 5 × 10{sup 15} cm{sup −2} and is in accordance with the calculated value. The results obtained by the method of the Raman scattering of light confirm conservation of crystalline structure and the start of the amorphization process.

  6. Aqueous marker penetration into ion irradiated polyimide

    NASA Astrophysics Data System (ADS)

    Fink, D.; Müller, M.; Petrov, A.; Klett, R.; Palmetshofer, L.; Hnatowicz, V.; Vacik, J.; Cervena, J.; Chadderton, L. T.

    2002-05-01

    The penetration of aqueous 6Li + markers into low energy ion irradiated polyimide (PI) foils was examined by the neutron depth profiling technique in combination with a modified tomographic approach. The ion irradiation always leads to an enhancement in marker uptake. After irradiation at low fluence the marker profiles follow the nuclear damage distribution even in three dimensions. At elevated fluences saturation in the marker uptake is clearly seen. The polymer's penetrant uptake can be described well by regular diffusion, with nuclear damage centres acting as saturable traps. These observations are strikingly different from the marker penetration into high-energy heavy-ion irradiated PI.

  7. Damage nucleation in Si during ion irradiation

    SciTech Connect

    Holland, O.W.; Fathy, D.; Narayan, J.

    1984-01-01

    Damage nucleation in single crystals of silicon during ion irradiation is investigated. Experimental results and mechanisms for damage nucleation during both room and liquid nitrogen temperature irradiation with different mass ions are discussed. It is shown that the accumulation of damage during room temperature irradiation depends on the rate of implantation. These dose rate effects are found to decrease in magnitude as the mass of the ions is increased. The significance of dose rate effects and their mass dependence on nucleation mechanisms is discussed.

  8. [Light irradiator for various chronic pain].

    PubMed

    Ide, Yasuo

    2014-07-01

    Effects of light upon human tissue are divided into irreversible effects and reversible effects. Irreversible effects can be called as high level laser therapy (HLLT), and reversible effects can be called as low level light therapy (LLLT). Light irradiators for chronic pain act under principle of LLLT. Laser diode, halogen lamp and xenon lamp are used as light sources for light irradiator for various chronic pain. These days, light emitting diode (LED) is used as light source for light irradiator for various kinds of pain. Light irradiators are now divided into portable light weight low power machine and heavy weight, high power machine. In the dental area Nd : YAG laser is using as HLLT tool. But, now there are many reports about Nd : YAG laser used as anesthetic machine. In these reports, topical anesthetic effects of Nd : YAG laser are immediate and with fewer side effects compared with topical anesthetic agents. These effects are explained as LLLT. Halogen lamp and xenon lamp type irradiators were also introduced. MEDILASER SOFT PULSE10, an laser diode type irradiator was withdrawn from the market.

  9. [Near infrared light irradiator using halogen lamp].

    PubMed

    Ide, Yasuo

    2012-07-01

    The practical electric light bulb was invented by Thomas Alva Edison in 1879. Halogen lamp is the toughest and brightest electric light bulb. With light filter, it is used as a source of near infrared light. Super Lizer and Alphabeam are made as near infrared light irradiator using halogen lamp. The light emmited by Super Lizer is linear polarized near infrared light. The wave length is from 600 to 1,600 nm and strongest at about 1,000 nm. Concerning Super Lizer, there is evidence of analgesic effects and normalization of the sympathetic nervous system. Super Lizer has four types of probes. SG type is used for stellate ganglion irradiation. B type is used for narrow area irradiation. C and D types are for broad area irradiation. The output of Alphabeam is not polarized. The wave length is from 700 to 1,600 nm and the strongest length is about 1,000nm. Standard attachment is used for spot irradiation. Small attachment is used for stellate ganglion irradiation. Wide attachment is used for broad area irradiation. The effects of Alphabeam are thought to be similar to that of Super Lizer.

  10. Ion irradiation of ammonia/carbon dioxide mixtures

    NASA Astrophysics Data System (ADS)

    Lv, X. Y.; Boduch, P.; Ding, J. J.; Domaracka, A.; Langlinay, T.; Palumbo, M. E.; Rothard, H.; Strazzulla, G.

    2013-09-01

    We present new experimental results on the thermal and ion irradiation processing of ammonia/carbon dioxide frozen mixtures. Mixtures deposited at low T (16 K) have then been warmed up to 160 K. During warm up complex chemical reactions occur leading to the formation of new molecules and, in particular, of ammonium carbamate. Other samples have been irradiated with 144 keV S9+ ions. Also in this case new chemical species are formed among which CO and OCN-. The results are discussed in the light of their relevance to understand the effects of different processes going on in the variegated superficial and sub-superficial layers of Enceladus.

  11. Li + grafting of ion irradiated polyethylene

    NASA Astrophysics Data System (ADS)

    Švorčík, V.; Rybka, V.; Vacík, J.; Hnatowicz, V.; Öchsner, R.; Ryssel, H.

    1999-02-01

    Foils of oriented polyethylene (PE) were irradiated with 63 keV Ar + and 155 keV Xe + ions to different fluences at room temperature and then doped from water solution of LiCl. The as irradiated and irradiated plus doped samples were examined by IR, EPR and neutron depth profiling (NDP) technique. The sheet resistance was also measured by the standard two points method. After Li salt doping of ion modified layer of PE, a reaction between degraded macromolecules and Li occur and thus a new chemical structure C-Li + is formed. Owing to the presence of these cations on the polymer chain, the irradiated plus doped layer exhibits higher electric conductivity compared to as-irradiated ones.

  12. Characterization of swift heavy ion irradiation damage in ceria

    SciTech Connect

    Yablinsky, Clarissa; Devanathan, Ram; Pakarinen, Janne; Gan, Jian; Severin, Daniel; Trautmann, Christina; Allen, T. R.

    2015-05-14

    We have examined microstructural evolution in irradiated ceria (CeO2) using swift heavy ion irradiation, electron microscopy, and atomistic simulation. CeO2, a UO2 fuel surrogate, was irradiated with gold ions at an energy of 1 GeV to fluences up to 1x1014 ions/cm2. Transmission electron microscopy accompanied by electron energy loss spectroscopy showed that the ion tracks were of similar size at all fluences, and that there was no chemical change in the ion track core. Classical molecular dynamics simulations of thermal spikes in CeO2 with energy deposition of 12 and 36 keV/nm show damage consisting of isolated point defects at the lower energy and defect clusters at 36 keV/nm, with no amorphization at either energy. Inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.

  13. Modifications of optical properties of PC/ABS by dual ions beam irradiation

    NASA Astrophysics Data System (ADS)

    Park, Jae-Won; Lee, Jae-Sang; Lee, Byung-hoon; Kim, Min-kyu; Moon, Byung-Sik; Lee, Chan-Young; Choi, Byung-Ho

    2013-03-01

    Polycarbonate (PC)/acrylonitrile butadien styrene (ABS) blends used in the inner parts of automobiles require a glossy and metallic colored optical property. Such a surface can be produced by ion beam irradiation, but the surface treated by a single ion species irradiation tends to be degraded upon a long term exposure under UV and visible lights, which includes the loss of glossiness and the delamination of the irradiated layer. Such degradations can be prevented or greatly reduced by a combined irradiation of heavy and light ions such as N and He ions. This may be attributable to a graded interface between the irradiation affected layer and the base materials by overlapping penetration depths of the heavy and light ions. This work is motivated by an effort to substitute the conventional Cr plating process with the ion beam process in the automobile industry.

  14. Ion irradiation effects on metallic nanocrystals

    SciTech Connect

    Kluth, P.; Johannessen, B.; Giulian, R.; Schnohr, C.S.; Foran, G.J.; Cookson, D.J.; Byrne, A.P.; Ridgway, M.C.

    2008-04-02

    We have investigated structural and morphological properties of metallic nanocrystals (NCs) exposed to ion irradiation. NCs were characterized by transmission electron microscopy in combination with advanced synchrotron-based analytical techniques, in particular X-ray absorption spectroscopy and small-angle X-ray scattering. A number of different effects were observed depending on the irradiation conditions. At energies where nuclear stopping is predominant, structural disorder/amorphization followed by inverse Ostwald ripening/dissolution due to ion beam mixing was observed for Au and Cu NCs embedded in SiO{sub 2}. The ion-irradiation-induced crystalline to amorphous transition in the NCs, which cannot be achieved in the corresponding bulk metals, was attributed to their initially higher structural energy as compared to bulk material and possibly preferential nucleation of the amorphous phase at the NC/SiO{sub 2} interface. At very high irradiation energies (swift heavy ion irradiation), where the energy loss is nearly entirely due to electronic stopping, a size-dependent shape transformation of the NCs from spheres to rod like shapes was apparent in Au NCs. Our preliminary results are in good agreement with considerations on melting of the NCs in the ion track as one mechanism involved in the shape transformation.

  15. Slow ion irradiation of sugar: astrobiological implications

    NASA Astrophysics Data System (ADS)

    Tuleta, M.; Gabla, L.; Wickramasinghe, N. C.

    2009-10-01

    As a result of irradiation by slow hydrogen and argon ions of saccharose, humic films having a fractal nature were produced. The use of hydrogen ions simulated roughly the interaction of low-energy solar wind protons with interplanetary dust grains which, in addition to organic and mineral dust, may include clumps of viable bacteria. The type of film generated by this experimental procedure could play a role in shielding the interior of micron-sized clumps from damaging ultraviolet and low-energy cosmic ray irradiation. We argue that such films may have played a role in processes that led to the initial origin of life, and following the emergence of life the same types of films (as, for instance, in biofilms surrounding cells) may have been modified by irradiation to offer protection to viable cells in the interior.

  16. Early and Late Responses to Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Schulte, Reinhard; Ling, Ted

    Early and late responses to ion beam therapy (IBT) are the result of complex interactions between host, dose volume, and radiobiological factors. Our understanding of these early and late tissue responses has improved greatly with the accumulation of laboratory and clinical experience with proton and heavy ion irradiation. With photon therapy becoming increasingly conformal, many concepts developed for 3D conformal radiotherapy and intensity modulated radiation therapy with photons are also applicable to IBT. This chapter reviews basic concepts and experimental data of early and late tissue responses to protons and ions.

  17. Cadmium Nanowire Formation Induced by Ion Irradiation

    SciTech Connect

    Jiang, Weilin; Weber, William J.; Wang, Chong M.; Young, James S.; Boatner, Lynn A.; Lian, Jie; Wang, Lumin; Ewing, Rodney C.

    2005-07-04

    One-dimensional nanostructures, such as nanowires, of semiconductors and metals are of great technological interest due to their potential for many advanced technology applications. Utilization of these materials versus their bulk counterparts will not only allow for device miniaturisation, but also may improve device performance or create new functions. Here we report a novel method for the synthesis of crystalline Cd-nanowires without involving either templates or a “seeded” structure. Ion irradiation at low temperatures (≤ 295 K) has been used to induce material decomposition and phase segregation in a cadmium niobate pyrochlore (Cd2Nb2O7) wafer. During the formation and rupture of the gas-filled blisters in the material, soft metallic Cd is extruded/extracted as nanowires through pores in the exfoliated layer. The entire process may be readily controlled by changing the ion irradiation conditions (e.g., ion species, dose and energy) with minimal thermal constraints.

  18. Mutation induced with ion beam irradiation in rose

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Nagatomi, S.; Morishita, T.; Degi, K.; Tanaka, A.; Shikazono, N.; Hase, Y.

    2003-05-01

    The effects of mutation induction by ion beam irradiation on axillary buds in rose were investigated. Axillary buds were irradiated with carbon and helium ion beams, and the solid mutants emerged after irradiation by repeated cutting back. In helium ion irradiation, mutations were observed in plants derived from 9 buds among 56 irradiated buds in 'Orange Rosamini' and in plants derived from 10 buds among 61 irradiated buds in 'Red Minimo'. In carbon ion, mutations were observed in plants derived from 12 buds among 88 irradiated buds in 'Orange Rosamini'. Mutations were induced not only in higher doses but also in lower doses, with which physiological effect by irradiation was hardly observed. Irradiation with both ion beams induced mutants in the number of petals, in flower size, in flower shape and in flower color in each cultivar.

  19. Chromosomal instability induced by heavy ion irradiation

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  20. Chromosomal instability induced by heavy ion irradiation

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  1. Nanoscale Morphology Evolution Under Ion Irradiation

    SciTech Connect

    Aziz, Michael J.

    2014-11-10

    We showed that the half-century-old paradigm of morphological instability under irradiation due to the curvature-dependence of the sputter yield, can account neither for the phase diagram nor the amplification or decay rates that we measure in the simplest possible experimental system -- an elemental semiconductor with an amorphous surface under noble-gas ion irradiation; We showed that a model of pattern formation based on the impact-induced redistribution of atoms that do not get sputtered away explains our experimental observations; We developed a first-principles, parameter-free approach for predicting morphology evolution, starting with molecular dynamics simulations of single ion impacts, lasting picoseconds, and upscaling through a rigorous crater-function formalism to develop a partial differential equation that predicts morphology evolution on time scales more than twelve orders of magnitude longer than can be covered by the molecular dynamics; We performed the first quantitative comparison of the contributions to morphological instability from sputter removal and from impact-induced redistribution of atoms that are removed, and showed that the former is negligible compared to the latter; We established a new paradigm for impact-induced morphology evolution based on crater functions that incorporate both redistribution and sputter effects; and We developed a model of nanopore closure by irradiation-induced stress and irradiationenhanced fluidity, for the near-surface irradiation regime in which nuclear stopping predominates, and showed that it explains many aspects of pore closure kinetics that we measure experimentally.

  2. Characterization of swift heavy ion irradiation damage in ceria

    DOE PAGES

    Yablinsky, Clarissa A.; Devanathan, Ram; Pakarinen, Janne; ...

    2015-03-04

    Swift heavy ion induced radiation damage is investigated for ceria (CeO2), which serves as a UO2 fuel surrogate. Microstructural changes resulting from an irradiation with 940 MeV gold ions of 42 keV/nm electronic energy loss are investigated by means of electron microscopy accompanied by electron energy loss spectroscopy showing that there exists a small density reduction in the ion track core. While chemical changes in the ion track are not precluded, evidence of them was not observed. Classical molecular dynamics simulations of thermal spikes in CeO2 with an energy deposition of 12 and 36 keV/nm show damage consisting of isolatedmore » point defects at 12 keV/nm, and defect clusters at 36 keV/nm, with no amorphization at either energy. Furthermore, inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.« less

  3. Characterization of swift heavy ion irradiation damage in ceria

    SciTech Connect

    Yablinsky, Clarissa A.; Devanathan, Ram; Pakarinen, Janne; Gan, Jian; Severin, Daniel; Trautmann, Christina; Allen, Todd R.

    2015-03-04

    Swift heavy ion induced radiation damage is investigated for ceria (CeO2), which serves as a UO2 fuel surrogate. Microstructural changes resulting from an irradiation with 940 MeV gold ions of 42 keV/nm electronic energy loss are investigated by means of electron microscopy accompanied by electron energy loss spectroscopy showing that there exists a small density reduction in the ion track core. While chemical changes in the ion track are not precluded, evidence of them was not observed. Classical molecular dynamics simulations of thermal spikes in CeO2 with an energy deposition of 12 and 36 keV/nm show damage consisting of isolated point defects at 12 keV/nm, and defect clusters at 36 keV/nm, with no amorphization at either energy. Furthermore, inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.

  4. Characterization of swift heavy ion irradiation damage in ceria

    SciTech Connect

    Yablinsky, Clarissa A.; Devanathan, Ram; Pakarinen, Janne; Gan, Jian; Severin, Daniel; Trautmann, Christina; Allen, Todd R.

    2015-03-04

    Swift heavy ion induced radiation damage is investigated for ceria (CeO2), which serves as a UO2 fuel surrogate. Microstructural changes resulting from an irradiation with 940 MeV gold ions of 42 keV/nm electronic energy loss are investigated by means of electron microscopy accompanied by electron energy loss spectroscopy showing that there exists a small density reduction in the ion track core. While chemical changes in the ion track are not precluded, evidence of them was not observed. Classical molecular dynamics simulations of thermal spikes in CeO2 with an energy deposition of 12 and 36 keV/nm show damage consisting of isolated point defects at 12 keV/nm, and defect clusters at 36 keV/nm, with no amorphization at either energy. Inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.

  5. Comparison of gain degradation and deep level transient spectroscopy in pnp Si bipolar junction transistors irradiated with different ion species

    SciTech Connect

    Aguirre, B. A.; Bielejec, E.; Fleming, R. M.; Vizkelethy, G.; Vaandrager, B.; Campbell, J.; Martin, W. J.; King, D. B.

    2016-12-09

    Here, we studied the effect of light ion and heavy ion irradiations on pnp Si BJTs. A mismatch in DLTS deep peak amplitude for devices with same final gain but irradiated with different ion species was observed. Also, different ions cause different gain degradation when the DLTS spectra are matched. Pre-dosed ion-irradiated samples show that ion induced ionization does not account for the differences in DLTS peak height but isochronal annealing studies suggest that light ions produce more VP defects than heavy ions to compensate for the lack of clusters that heavy ions produce. The creation of defect clusters by heavy ions is evident by the higher content of E4 and V*2 defects compared to light ions.

  6. Comparison of gain degradation and deep level transient spectroscopy in pnp Si bipolar junction transistors irradiated with different ion species

    DOE PAGES

    Aguirre, B. A.; Bielejec, E.; Fleming, R. M.; ...

    2016-12-09

    Here, we studied the effect of light ion and heavy ion irradiations on pnp Si BJTs. A mismatch in DLTS deep peak amplitude for devices with same final gain but irradiated with different ion species was observed. Also, different ions cause different gain degradation when the DLTS spectra are matched. Pre-dosed ion-irradiated samples show that ion induced ionization does not account for the differences in DLTS peak height but isochronal annealing studies suggest that light ions produce more VP defects than heavy ions to compensate for the lack of clusters that heavy ions produce. The creation of defect clusters bymore » heavy ions is evident by the higher content of E4 and V*2 defects compared to light ions.« less

  7. Nb2O5 Nanostructure Evolution on Nb Surfaces via Low-Energy He(+) Ion Irradiation.

    PubMed

    Novakowski, Theodore Joseph; Tripathi, Jitendra Kumar; Hassanein, Ahmed

    2016-12-21

    We propose low-energy, broad-beam He(+) ion irradiation as a novel processing technique for the generation of Nb2O5 surface nanostructures due to its relative simplicity and scalability in a commercial setting. Since there have been relatively few studies involving the interaction of high-fluence, low-energy He(+) ion irradiation and Nb (or its oxidized states), this systematic study explores both effects of fluence and sample temperature during irradiation on resulting surface morphology. Detailed normal and cross-sectional scanning electron microscopy (SEM) studies reveal subsurface He bubble formation and elucidate potential driving mechanisms for nanostructure evolution. A combination of specular optical reflectivity and X-ray photoelectron spectroscopy (XPS) is also used to gain additional information on roughness and stoichiometry of irradiated surfaces. Our investigations show significant surface modification for all tested irradiation conditions; the resulting surface structure size and geometry have a strong dependence on both sample temperature during irradiation and total ion fluence. Optical reflectivity measurements on irradiated surfaces demonstrate increased surface roughening with increasing ion fluence, and XPS shows higher oxidation levels for samples irradiated at lower temperatures, suggesting larger surface roughness and porosity. Overall, it was found that low-energy He(+) ion irradiation is an efficient processing technique for nanostructure formation, and surface structures are highly tunable by adjusting ion fluence and Nb2O5 sample temperature during irradiation. These findings may have excellent potential applications for solar energy conversion through improved efficiency due to effective light absorption.

  8. Phase transformations in ion-irradiated silicides

    NASA Technical Reports Server (NTRS)

    Hewett, C. A.; Lau, S. S.; Suni, I.; Hung, L. S.

    1985-01-01

    The present investigation has three objectives. The first is concerned with the phase transformation of CoSi2 under ion implantation and the subsequent crystallization characteristics during annealing, taking into account epitaxial and nonepitaxial recrystallization behavior. The second objective is related to a study of the general trend of implantation-induced damage and crystallization behavior for a number of commonly used silicides. The last objective involves a comparison of the recrystallization behavior of cosputtered refractory silicides with that of the ion-implanted silicides. It was found that epitaxial regrowth of ion-irradiated CoSi2 occurred for samples with an epitaxial seed left at the Si/CoSi2 interface. A structural investigation of CoSi2 involving transmission electron microscopy (TEM) showed that after high-dose implantation CoSi2 is amorphous.

  9. Local brain heavy ion irradiation induced Immunosuppression

    NASA Astrophysics Data System (ADS)

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

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

  10. Materials Modification Under Ion Irradiation: JANNUS Project

    SciTech Connect

    Serruys, Y.; Trocellier, P.; Trouslard, Ph.

    2004-12-01

    JANNUS (Joint Accelerators for Nano-Science and Nuclear Simulation) is a project designed to study the modification of materials using multiple ion beams and in-situ TEM observation. It will be a unique facility in Europe for the study of irradiation effects, the simulation of material damage due to irradiation and in particular of combined effects. The project is also intended to bring together experimental and modelling teams for a mutual fertilisation of their activities. It will also contribute to the teaching of particle-matter interactions and their applications. JANNUS will be composed of three accelerators with a common experimental chamber and of two accelerators coupled to a 200 kV TEM.

  11. High temperature annealing of ion irradiated tungsten

    DOE PAGES

    Ferroni, Francesco; Yi, Xiaoou; Arakawa, Kazuto; ...

    2015-03-21

    In this study, transmission electron microscopy of high temperature annealing of pure tungsten irradiated by self-ions was conducted to elucidate microstructural and defect evolution in temperature ranges relevant to fusion reactor applications (500–1200°C). Bulk isochronal and isothermal annealing of ion irradiated pure tungsten (2 MeV W+ ions, 500°C, 1014 W+/cm2) with temperatures of 800, 950, 1100 and 1400°C, from 0.5 to 8 h, was followed by ex situ characterization of defect size, number density, Burgers vector and nature. Loops with diameters larger than 2–3 nm were considered for detailed analysis, among which all loops had View the MathML source andmore » were predominantly of interstitial nature. In situ annealing experiments from 300 up to 1200°C were also carried out, including dynamic temperature ramp-ups. These confirmed an acceleration of loop loss above 900°C. At different temperatures within this range, dislocations exhibited behaviour such as initial isolated loop hopping followed by large-scale rearrangements into loop chains, coalescence and finally line–loop interactions and widespread absorption by free-surfaces at increasing temperatures. An activation energy for the annealing of dislocation length was obtained, finding Ea=1.34±0.2 eV for the 700–1100°C range.« less

  12. High temperature annealing of ion irradiated tungsten

    SciTech Connect

    Ferroni, Francesco; Yi, Xiaoou; Fitzgerald, Steven P.; Edmondson, Philip D.; Roberts, Steve G.

    2015-03-21

    In this study, transmission electron microscopy of high temperature annealing of pure tungsten irradiated by self-ions was conducted to elucidate microstructural and defect evolution in temperature ranges relevant to fusion reactor applications (500–1200°C). Bulk isochronal and isothermal annealing of ion irradiated pure tungsten (2 MeV W+ ions, 500°C, 1014 W+/cm2) with temperatures of 800, 950, 1100 and 1400°C, from 0.5 to 8 h, was followed by ex situ characterization of defect size, number density, Burgers vector and nature. Loops with diameters larger than 2–3 nm were considered for detailed analysis, among which all loops had View the MathML source and were predominantly of interstitial nature. In situ annealing experiments from 300 up to 1200°C were also carried out, including dynamic temperature ramp-ups. These confirmed an acceleration of loop loss above 900°C. At different temperatures within this range, dislocations exhibited behaviour such as initial isolated loop hopping followed by large-scale rearrangements into loop chains, coalescence and finally line–loop interactions and widespread absorption by free-surfaces at increasing temperatures. An activation energy for the annealing of dislocation length was obtained, finding Ea=1.34±0.2 eV for the 700–1100°C range.

  13. Raman spectroscopy of ion irradiated diamond

    NASA Astrophysics Data System (ADS)

    Brunetto, R.; Baratta, G. A.; Strazzulla, G.

    2004-07-01

    Ion irradiation experiments of diamond samples at room temperature have been performed by using in situ Raman spectroscopy as diagnostic technique. Different ions are used with energies of 200 or 400 keV. The area of virgin diamond Raman band (at 1332 cm-1) decreases exponentially as the ion fluence increases. This is due to changes in the optical properties of the damaged samples in the visible spectral range. Results from different ions demonstrate that this effect is correlated with the number of displacements/cm2, i.e., with the energy lost by ions through elastic collisions with target nuclei. Amorphous carbon (sp2) is formed after a threshold of about 2×1022 vacancies/cm3, or about 16 eV/C-atom deposited by elastic collisions. The peak position and full width at half maximum of the D line and G line of the synthesized amorphous carbon are studied. In particular, the G-line peak position shifts from the initial 1545 cm-1 to about 1515 cm-1 at the higher doses. The results are also discussed in view of their relevance in astrophysical environments.

  14. Metastable hydronium ions in UV-irradiated ice

    SciTech Connect

    Moon, Eui-Seong; Kang, Heon

    2012-11-28

    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.

  15. Raman spectroscopy of ion-irradiated astrophysically relevant materials

    NASA Astrophysics Data System (ADS)

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

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

  16. Ion Irradiation of Carbon Nanotubes: a STM Study

    NASA Astrophysics Data System (ADS)

    Osváth, Z.; Vértesy, G.; Horváth, Z. E.; Gyulai, J.; Biró, L. P.

    2009-03-01

    Multi-walled carbon nanotubes irradiated with Ar+ ions of low (5×1011 ions/cm2) and high (1015 ions/cm2) fluences were investigated by STM. Contrary to the case of low fluence irradiation, the defects produced during the high fluence irradiation could not be observed individually, and the surface of nanotubes became rough. Irradiated nanotubes could be easily bent by the STM tip. However, some nanotubes parts could not be moved, which suggest that these parts were bound to the substrate during irradiation.

  17. Molecular dynamics simulations of ion range profiles for heavy ions in light targets

    SciTech Connect

    Lan, Chune; Xue, Jianming; Zhang, Yanwen; Morris, James R.; Zhu, Zihua; Gao, Yuan; Wang, Yugang; Yan, Sha; Weber, William J.

    2012-09-01

    The determination of stopping powers for slow heavy ions in targets containing light elements is important to accurately describe ion-solid interactions, evaluate ion irradiation effects and predict ion ranges for device fabrication and nuclear applications. Recently, discrepancies of up to 40% between the experimental results and SRIM (Stopping and Range of Ions in Matter) predictions of ion ranges for heavy ions with medium and low energies (<25 keV/nucleon) in light elemental targets have been reported. The longer experimental ion ranges indicate that the stopping powers used in the SRIM code are overestimated. Here, a molecular dynamics simulation scheme is developed to calculate the ion ranges of heavy ions in light elemental targets. Electronic stopping powers generated from both a reciprocity approach and the SRIM code are used to investigate the influence of electronic stopping on ion range profiles. The ion range profiles for Au and Pb ions in SiC and Er ions in Si, with energies between 20 and 5250 keV, are simulated. The simulation results show that the depth profiles of implanted ions are deeper and in better agreement with the experiments when using the electronic stopping power values derived from the reciprocity approach. These results indicate that the origin of the discrepancy in ion ranges between experimental results and SRIM predictions in the low energy region may be an overestimation of the electronic stopping powers used in SRIM.

  18. Molecular dynamics simulations of ion range profiles for heavy ions in light targets

    SciTech Connect

    Lan, Chune; Xue, Jianming; Zhang, Yanwen; Morris, James R; Zhu, Zihua; Gao, Yuan; Wang, Yugang; Yan, Sha; Weber, William J

    2012-01-01

    The determination of stopping powers for slow heavy ions in targets containing light elements is important to accurately describe ion-solid interactions, evaluate ion irradiation effects and predict ion ranges for device fabrication and nuclear applications. Recently, discrepancies of up to 40% between the experimental results and SRIM (Stopping and Range of Ions in Matter) predictions of ion ranges for heavy ions with medium and low energies (< {approx} 25 keV/nucleon) in light elemental targets have been reported. The longer experimental ion ranges indicate that the stopping powers used in the SRIM code are overestimated. Here, a molecular dynamics simulation scheme is developed to calculate the ion ranges of heavy ions in light elemental targets. Electronic stopping powers generated from both a reciprocity approach and the SRIM code are used to investigate the influence of electronic stopping on ion range profiles. The ion range profiles for Au and Pb ions in SiC and Er ions in Si, with energies between 20 and 5250 keV, are simulated. The simulation results show that the depth profiles of implanted ions are deeper and in better agreement with the experiments when using the electronic stopping power values derived from the reciprocity approach. These results indicate that the origin of the discrepancy in ion ranges between experimental results and SRIM predictions in the low energy region may be an overestimation of the electronic stopping powers used in SRIM.

  19. Hydrogen retention in ion irradiated steels

    SciTech Connect

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

    1998-11-01

    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%.

  20. Light ion concentrations in Jupiter's inner magnetosphere

    NASA Technical Reports Server (NTRS)

    Tokar, R. L.; Gurnett, D. A.; Shaw, R. R.; Bagenal, F.

    1982-01-01

    The light ion distribution in the inner Jovian magnetosphere is investigated using whistler dispersion measurements from the Voyager 1 plasma wave instrument and heavy ion plasma concentrations from the plasma instrument. Two models are developed for the light ion concentration over 14 L shells between L = 5.2 and 6.2, one giving a constant concentration along the field line and the other corresponding to an exponential density distribution. Due to heavy ion concentrations near the equator that are typically an order of magnitude larger than the light ion concentration, results obtained are mainly relevant to the light ion concentration outside of the torus. Light ion concentration near the equator ranges from about 1-10% of the heavy ion concentration, while outside the torus the light ions are the dominant species.

  1. Surface Modification of Polymer Substrates by Oxygen Ion Irradiation

    SciTech Connect

    Takaoka, G. H.; Ryuto, H.; Araki, R.; Yakushiji, T.

    2008-11-03

    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.

  2. Surface Modification of Polymer Substrates by Oxygen Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Takaoka, G. H.; Ryuto, H.; Araki, R.; Yakushiji, T.

    2008-11-01

    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.

  3. Light-controlled ion channels formed by amphiphilic small molecules regulate ion conduction via cis-trans photoisomerization.

    PubMed

    Liu, Tao; Bao, Chunyan; Wang, Haiyan; Lin, Yao; Jia, Huijuan; Zhu, Linyong

    2013-11-11

    Light-regulated ion channel-transport across lipid bilayers was realized using structurally simple azobenzene-based amphiphilic small molecules. UV or visible irradiation triggers molecular photoisomerization, which induces structural and membrane affinity changes in self-assembled channels, thus resulting in light-regulated ion transmembrane transport.

  4. Luminescence imaging of water during carbon-ion irradiation for range estimation.

    PubMed

    Yamamoto, Seiichi; Komori, Masataka; Akagi, Takashi; Yamashita, Tomohiro; Koyama, Shuji; Morishita, Yuki; Sekihara, Eri; Toshito, Toshiyuki

    2016-05-01

    The authors previously reported successful luminescence imaging of water during proton irradiation and its application to range estimation. However, since the feasibility of this approach for carbon-ion irradiation remained unclear, the authors conducted luminescence imaging during carbon-ion irradiation and estimated the ranges. The authors placed a pure-water phantom on the patient couch of a carbon-ion therapy system and measured the luminescence images with a high-sensitivity, cooled charge-coupled device camera during carbon-ion irradiation. The authors also carried out imaging of three types of phantoms (tap-water, an acrylic block, and a plastic scintillator) and compared their intensities and distributions with those of a phantom containing pure-water. The luminescence images of pure-water phantoms during carbon-ion irradiation showed clear Bragg peaks, and the measured carbon-ion ranges from the images were almost the same as those obtained by simulation. The image of the tap-water phantom showed almost the same distribution as that of the pure-water phantom. The acrylic block phantom's luminescence image produced seven times higher luminescence and had a 13% shorter range than that of the water phantoms; the range with the acrylic phantom generally matched the calculated value. The plastic scintillator showed ∼15 000 times higher light than that of water. Luminescence imaging during carbon-ion irradiation of water is not only possible but also a promising method for range estimation in carbon-ion therapy.

  5. Spectral properties of ion irradiated carbon rich solids

    NASA Astrophysics Data System (ADS)

    Strazzulla, G.; Baratta, G.; Brunetto, R.; Garozzo, M.; Kanuchova, Z.

    2009-04-01

    Carbon rich solid materials have been studied before, during, and after ion irradiation (3-400 keV ions) by in situ reflectance spectroscopy (from UV to IR). Frozen hydrocarbons (benzene, methane, butane, acetylene, etc., also mixed with water ice) have been irradiated at low temperature with fast ions. Irradiation causes the formation of many molecular species and of a long chain polymer like material (organic refractory residue). The process mimics what occurs in space because of cosmic ion irradiation of the icy surfaces of some objects in the Solar System. Other irradiated materials include natural bitumens (Asphaltite, kerite) and polymers (i.e. polystyrene). Upon irradiation the originally transparent polymer samples are converted in a material that, already at low doses, strongly absorbs in the UV. Such materials could mimic a kind of organic material (i.e. a spectrally neutral one) freshly exposed at the surface of minor objects in the Solar System because of meteoritic impact.

  6. Synthesis of Metal Ion-Doped TiO2 Nanoparticles Using Two-Phase Method and Their Photocatalytic Activity Under Visible Light Irradiation.

    PubMed

    Nguyen, Duy-Trinh; Hong, Seong-Soo

    2016-02-01

    In this study, TiO2 and metal ion-doped TiO2 nanoparticles were successfully synthesized by solvothermal reaction of titanium butoxide precursor in the presence of oleic acid, oleylamine and vapor water and they were characterized by XRD, Raman, TEM and DRS. We also investigated the photocatalytic activity of these oxides for the decomposition of Rhodamine B. From XRD and Raman results, doping of the metal ion in the crystal lattice did not change the high crystallinity of the TiO2 structure, and all the metal ions were incorporated into the structures of titania as well as replaced titanium ion or located at interstitial site. The absorption band shifted to a higher wavelength on the metal ion-doped TiO2 samples compared to the pure TiO2 sample. The Ce ion- doped TiO2 catalysts showed the higher photocatalytic activity compared to the pure TiO2 and a commercial P-25 catalysts and 1% Ce-doped TiO2 showed the highest photocatalytic activity.

  7. Carbon nanowires generated by ion irradiation of hydrocarbon ices

    NASA Astrophysics Data System (ADS)

    Puglisi, O.; Compagnini, G.; D'Urso, L.; Baratta, G. A.; Palumbo, M. E.; Strazzulla, G.

    2014-05-01

    In this paper we present the formation of carbon nanowires (polyynes and polycumulenes) in the solid state by ion irradiation of frozen hydrocarbons (C6H6 and C2H2). Irradiations have been performed using H+ ions in the 100's keV energy regime using fluences up to 5 × 1014 ions/cm2. Beyond the intrinsic significance of these results in the field of material science, this work has been motivated by the fact that ion beam irradiation of hydrocarbon ices is one of the most important process thought to happen in several extraterrestrial environments where many spectroscopic features of polyyne molecules have been identified.

  8. Concurrent in situ ion irradiation transmission electron microscope

    DOE PAGES

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

    2014-08-29

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

  9. Concurrent in situ ion irradiation transmission electron microscope

    DOE PAGES

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

    2014-08-29

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

  10. Localised irradiance distribution found in dental light curing units.

    PubMed

    Michaud, Pierre-Luc; Price, Richard B T; Labrie, Daniel; Rueggeberg, Frederick A; Sullivan, Braden

    2014-02-01

    To measure the localised irradiance and wavelength distributions from dental light curing units (LCUs) and establish a method to characterise their output. Using a laboratory grade integrating sphere spectrometer system (Labsphere and Ocean Optics) the power, irradiance, and spectral emission were measured at the light tips of four LCUs: one plasma-arc (PAC) unit, one single peak blue light-emitting diode (blue-LED) unit, and two polywave LED (poly-LED) units. A beam profiler camera (Ophir Spiricon) was used to record the localised irradiance across the face of the light tips. The irradiance-calibrated beam profile images were then divided into 45 squares, each 1mm(2). Each square contained the irradiance information received from approximately 3200 pixels. The mean irradiance value within each square was calculated, and the distribution of irradiance values among these 45 squares across the tip-ends was examined. Additionally, the spectral emission was recorded at various regions across each light tip using the integrating sphere with a 4-mm diameter entrance aperture. The localised irradiance distribution was inhomogeneous in all four lights. The irradiance distribution was most uniformly distributed across the PAC tip. Both the irradiance and spectral emission from the poly-LED units were very unevenly distributed. Reporting a single irradiance value or a single spectral range to describe the output from a curing light is both imprecise and inappropriate. Instead, an image of both the irradiance distribution and the distribution of the spectral emission across the light tip should be provided. The localised beam irradiance profile at the tip of dental LCUs is not uniform. Poly-LED units may deliver spectrally inhomogeneous irradiance profiles. Depending on the photoinitiator used in the RBC and the orientation of the LCU over the tooth, this non-uniformity may cause inadequate and inhomogeneous resin polymerisation, leading to poor physical properties, and

  11. Ion irradiation of CH 4-containing icy mixtures

    NASA Astrophysics Data System (ADS)

    Baratta, G. A.; Domingo, M.; Ferini, G.; Leto, G.; Palumbo, M. E.; Satorre, M. A.; Strazzulla, G.

    2003-08-01

    We have studied by infrared absorption spectroscopy the effects of ion irradiation with 60 keV Ar 2+ ions on pure methane (CH 4) ice at 12 K and mixtures with water (H 2O) and nitrogen (N 2). Ion irradiation, among other effects, causes the rupture of original molecular bonds and the formation of molecular species not present in the initial ice. Here we present the experimental results and discuss their astrophysical relevance.

  12. Mechanical property measurements on ion-irradiated metals

    SciTech Connect

    Zinkle, S.J.; Oliver, W.C.

    1986-08-01

    A recently developed mechanical properties microprobe (MPM) has been used to investigate strength and elastic modulus changes in ion-irradiated metals. The indenter load and its displacement are simultaneously monitored while the indentation is being made and also during unloading. Microindentation hardness measurements have been performed on ion-irradiated copper and Cu-0.15% Zr (AMZIRC). The depth dependence of the ion damage has been investigated in selected specimens which were prepared using a cross-section technique. This procedure allows a direct comparison to be made of hardness data from different irradiation depths while the indent size is held constant. The displacement damage associated with ion irradiation caused either hardening or softening, depending on the irradiation conditions and the material.

  13. Short communication on "In-situ TEM ion irradiation investigations on U3Si2 at LWR temperatures"

    DOE PAGES

    Miao, Yinbin; Harp, Jason; Mo, Kun; ...

    2016-11-21

    Here, the radiation-induced amorphization of U3Si2 was investigated by in-situ transmission electron microscopy using 1 MeV Kr ion irradiation. Both arc-melted and sintered U3Si2 specimens were irradiated at room temperature to confirm the similarity in their responses to radiation. The sintered specimens were then irradiated at 350 °C and 550 °C up to 7.2 × 1015 ions/cm2 to examine their amorphization behavior under light water reactor (LWR) conditions. U3Si2 remains crystalline under irradiation at LWR temperatures. Oxidation of the material was observed at high irradiation doses.

  14. Short Communication on "In-situ TEM ion irradiation investigations on U3Si2 at LWR temperatures"

    NASA Astrophysics Data System (ADS)

    Miao, Yinbin; Harp, Jason; Mo, Kun; Bhattacharya, Sumit; Baldo, Peter; Yacout, Abdellatif M.

    2017-02-01

    The radiation-induced amorphization of U3Si2 was investigated by in-situ transmission electron microscopy using 1 MeV Kr ion irradiation. Both arc-melted and sintered U3Si2 specimens were irradiated at room temperature to confirm the similarity in their responses to radiation. The sintered specimens were then irradiated at 350 °C and 550 °C up to 7.2 × 1015 ions/cm2 to examine their amorphization behavior under light water reactor (LWR) conditions. U3Si2 remains crystalline under irradiation at LWR temperatures. Oxidation of the material was observed at high irradiation doses.

  15. Anti-biofilm activity of Fe heavy ion irradiated polycarbonate

    NASA Astrophysics Data System (ADS)

    Joshi, R. P.; Hareesh, K.; Bankar, A.; Sanjeev, Ganesh; Asokan, K.; Kanjilal, D.; Dahiwale, S. S.; Bhoraskar, V. N.; Dhole, S. D.

    2016-10-01

    Polycarbonate (PC) polymers were investigated before and after high energy heavy ion irradiation for anti-bacterial properties. These PC films were irradiated by Fe heavy ions with two energies, viz, 60 and 120 MeV, at different fluences in the range from 1 × 1011 ions/cm2 to 1 × 1013 ions/cm2. UV-Visible spectroscopic results showed optical band gap decreased with increase in ion fluences due to chain scission mainly at carbonyl group of PC which is also corroborated by Fourier transform infrared spectroscopic results. X-ray diffractogram results showed decrease in crystallinity of PC after irradiation which leads to decrease in molecular weight. This is confirmed by rheological studies and also by differential scanning calorimetric results. The irradiated PC samples showed modification in their surfaces prevents biofilm formation of human pathogen, Salmonella typhi.

  16. Ionoluminescence of fused silica under swift ion irradiation

    NASA Astrophysics Data System (ADS)

    Saavedra, R.; Jiménez-Rey, D.; Martin, P.; Vila, R.

    2016-09-01

    Ion beam induced luminescence spectra have been in-situ recorded during He+ (2.5 MeV), O4+ (13.5 MeV) and Si4+ (24.4 MeV) irradiations for three vitreous silica grades with different OH content (KU1, KS-4V and Infrasil 301). Remarkable changes in the ionoluminescence spectra of the three silica grades were observed for low ion fluences. He+ irradiated samples exhibited higher luminescence than equivalent ones irradiated with heavier O4+ and Si4+ ions. KU1 samples with the highest OH content showed the lowest blue luminescence. Blue luminescence maximum during ion irradiations with O4+ and Si4+ ions is correlated with structural changes.

  17. Swift Heavy Ion Irradiation Effects on NPN rf Power Transistors

    NASA Astrophysics Data System (ADS)

    Pushpa, N.; Prakash, A. P. Gnana; Gupta, S. K.; Revannasiddaiah, D.

    2011-07-01

    The dc characteristics of NPN rf power transistors were studied systematically before and after irradiation by 50 MeV Li3+ ions, 100 MeV F8+ ions and 140 MeV Si10+ ions in the dose range of 100 krad to 100 Mrad. The transistor parameters such as excess base current (ΔIB = IBpost-IBpre), dc current gain (hFE), and collector-saturation current (ICSat) were determined before and after irradiation. The base current (IB) was found to increase significantly after ion irradiation and this in turn decreases the hFE of the transistors. Further, the output characteristics of the irradiated devices exhibit the decrease in the collector current at the saturation region (ICSat) with increase of ion dose.

  18. Temperature response of several scintillator materials to light ions

    NASA Astrophysics Data System (ADS)

    Rodríguez-Ramos, M.; Jiménez-Ramos, M. C.; García-Muñoz, M.; García López, J.

    2017-07-01

    Ion beam induced luminescence has been used to study the response of scintillator screens of Y2O3:Eu3+ (P56) and SrGa2S4:Eu2+ (TG-Green) when irradiated with light ions (protons, deuterium and helium particles). The absolute efficiency of the samples has been studied as a function of the ion energy (with energies up to 3.5 MeV), the beam current and the operating temperature. The evolution of the scintillator yield with ion fluence has been carried out for all the scintillators to estimate radiation damage. Finally, measurements of the decay time of these materials using a system of pulsed beam accelerated particles have been done. Among the screens under study, the TG-Green is the best suited material, in terms of absolute efficiency, temporal response and degradation with ion dose, for fast-ion loss detectors in fusion devices.

  19. Mono and sequential ion irradiation induced damage formation and damage recovery in oxide glasses: Stopping power dependence of the mechanical properties

    NASA Astrophysics Data System (ADS)

    Mir, A. H.; Monnet, I.; Toulemonde, M.; Bouffard, S.; Jegou, C.; Peuget, S.

    2016-02-01

    Simple and complex borosilicate glasses were irradiated with single and double ion beams of light and heavy ions over a broad fluence and stopping power range. As a result of the heavy ion irradiation (U, Kr, Au), the hardness was observed to diminish and saturate after a decrease by 35 ± 1%. Unlike slow and swift heavy ion irradiation, irradiation with light ions (He,O) induced a saturation hardness decrease of 18 ± 1% only. During double ion beam irradiation; where glasses were first irradiated with a heavy ion (gold) and then by a light ion (helium), the light ion irradiation induced partial damage recovery. As a consequence of the recovery effect, the hardness of the pre-irradiated glasses increased by 10-15% depending on the chemical composition. These results highlight that the nuclear energy loss and high electronic energy loss (≥4 keV/nm) result in significant and similar modifications whereas light ions with low electronic energy loss (≤1 keV/nm) result in only mild damage formation in virgin glasses and recovery in highly pre-damaged glasses. These results are important to understand the damage formation and recovery in actinide bearing minerals and in glasses subjected to self-irradiation by alpha decays.

  20. An in situ transmission electron microscopy study of the ion irradiation induced amorphisation of silicon by He and Xe

    DOE PAGES

    Edmondson, P. D.; Abrams, K. J.; Hinks, J. A.; ...

    2015-11-21

    We used transmission electron microscopy with in situ ion irradiation to examine the ion-beam-induced amorphisation of crystalline silicon under irradiation with light (He) and heavy (Xe) ions at room temperature. Analysis of the electron diffraction data reveal the heterogeneous amorphisation mechanism to be dominant in both cases. Moreover, for the differences in the amorphisation curves are discussed in terms of intra-cascade dynamic recovery, and the role of electronic and nuclear loss mechanisms.

  1. Effect of irradiation temperature on microstructural changes in self-ion irradiated austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Jin, Hyung-Ha; Ko, Eunsol; Lim, Sangyeob; Kwon, Junhyun; Shin, Chansun

    2017-09-01

    We investigated the microstructural and hardness changes in austenitic stainless steel after Fe ion irradiation at 400, 300, and 200 °C using transmission electron microscopy (TEM) and nanoindentation. The size of the Frank loops increased and the density decreased with increasing irradiation temperature. Radiation-induced segregation (RIS) was detected across high-angle grain boundaries, and the degree of RIS increases with increasing irradiation temperature. Ni-Si clusters were observed using high-resolution TEM in the sample irradiated at 400 °C. The results of this work are compared with the literature data of self-ion and proton irradiation at comparable temperatures and damage levels on stainless steels with a similar material composition with this study. Despite the differences in dose rate, alloy composition and incident ion energy, the irradiation temperature dependence of RIS and the size and density of radiation defects followed the same trends, and were very comparable in magnitude.

  2. Hopping magnetoresistance in ion irradiated monolayer graphene

    NASA Astrophysics Data System (ADS)

    Shlimak, I.; Zion, E.; Butenko, A. V.; Wolfson, L.; Richter, V.; Kaganovskii, Yu.; Sharoni, A.; Haran, A.; Naveh, D.; Kogan, E.; Kaveh, M.

    2016-02-01

    Magnetoresistance (MR) of ion irradiated monolayer graphene samples with a variable-range hopping (VRH) mechanism of conductivity was measured at temperatures down to T=1.8 K in magnetic fields up to B=8 T. It was observed that in perpendicular magnetic fields, hopping resistivity R decreases, which corresponds to negative MR (NMR), while parallel magnetic field results in positive MR (PMR) at low temperatures. NMR is explained on the basis of the "orbital" model in which perpendicular magnetic field suppresses the destructive interference of many paths through the intermediate sites in the total probability of the long-distance tunneling in the VRH regime. At low fields, a quadratic dependence (| ΔR / R | ∼ B2) of NMR is observed, while at B > B*, the quadratic dependence is replaced by the linear one. It was found that all NMR curves for different samples and different temperatures could be merged into common dependence when plotted as a function of B/B*. It is shown that B* ∼ T1/2 in agreement with predictions of the "orbital" model. The obtained values of B* also allowed us to estimate the localization radius ξ of charge carriers for samples with a different degree of disorder. PMR in parallel magnetic fields is explained by suppression of hopping transitions via double occupied states due to alignment of electron spins.

  3. High-performance pure and Fe3+-ion doped ZnS quantum dots as green nanophotocatalysts for the removal of malachite green under UV-light irradiation.

    PubMed

    Rajabi, Hamid Reza; Khani, Omid; Shamsipur, Mojtaba; Vatanpour, Vahid

    2013-04-15

    The heterogeneous photocatalysis using UV-radiation and quantum dots (QDs) is an interesting method for the treatment of water polluted with the organic substances. In this study, ZnS QDs, as a pure and doped with Fe(3+), were prepared for photodecolorization of malachite green (MG) as a model dye. The synthesis of QDs was carried out using a chemical precipitation method in aqueous solution, in the presence of 2-mercaptoethanol as a capping agent. The XRD patterns indicated that the doped nanoparticles are crystalline, with cubic zinc blend structure. The effects of dopant content, pH, nanophotocatalyst amount, irradiation time, and initial dye concentration on the removal efficiency of MG were studied. Results showed that the QDs presented high MG decolorization efficiency, and doping with Fe(3+) promoted the dye removal. The maximum removal of dyes was obtained at 80 mg/L of photocatalyst as an optimum value for the dosage of photocatalyst in pH of 8.0. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Ion irradiation induced evolution of nanostructure in a graded multi-trilayer system

    NASA Astrophysics Data System (ADS)

    Roy, Sumalay; Ghatak, J.; Dev, B. N.

    2012-02-01

    Nanostructural modifications in a double-graded Pt/Ni/C multi-trilayer, due to irradiation by an energetic ion-beam, have been analyzed using X-ray reflectivity (XRR), X-ray standing wave (XSW) and cross-sectional transmission electron microscopy (X-TEM) techniques. 2 MeV Au2+ ions were rastered on Pt/Ni/C multi-trilayer samples producing a uniformly irradiated area at ion-fluences ranging from 1 × 1014 ions/cm2 to 2 × 1015 ions/cm2. Ion irradiation induced modifications of microstructural parameters, e.g., layer thicknesses and electron densities of individual layers and interface roughnesses have been obtained from XRR analysis. Pt- and Ni-fluorescence yield from the as-deposited sample under the XSW condition show the distinct existence of Pt and Ni layers. The almost indistinguishable Pt- and Ni-fluorescence data over the first order Bragg peak from the sample irradiated at the highest ion-fluence, suggest complete mixing of Pt and Ni. Strong mixing between Pt and Ni in the ion irradiated samples is also corroborated by XRR results. X-TEM studies reveal the individual layer structure in the as-deposited sample. This layer structure is lost in the sample irradiated at the highest ion fluence indicating a complete mixing between Pt and Ni layers and nanoscale grain growth of Pt-Ni alloys. Additionally, formation of Pt-Ni alloy nano-clusters in the C-layers is observed. The results are understood in the light of the positive heat of mixing between Pt and C, and Ni and C and the negative heat of mixing between Pt and Ni. The effect of heat of mixing becomes dominant at high fluence irradiation.

  5. He ion irradiation effects on multiwalled carbon nanotubes structure

    NASA Astrophysics Data System (ADS)

    Elsehly, Emad M.; Chechenin, Nikolay G.; Makunin, Alexey V.; Shemukhin, Andrey A.; Motaweh, Hussien A.

    2017-03-01

    Samples of multi-walled carbon nanotubes (MWNTs) were irradiated with 80 keV He ions. Scanning electron microscopy (SEM) inspection showed that the average outer diameters of the tube decreased as a result of ion irradiation. The samples were also characterized using Raman spectrometry by analysis of the intensity of main bands in the spectra of virgin and irradiated MWNT samples. Modifications of the disorder mode (D-band) and the tangential mode (G-band) were studied as a function of irradiation fluences. Raman spectra showed that as the fluence increases, the MWNTs first show disorder due to the produced defects, and then amorphization under still higher fluence of ion irradiation. Thermal and athermal mechanisms of the radiation induced MWNTs modifications are discussed. Contribution to the Topical Issue "Many Particle Spectroscopy of Atoms, Molecules, Clusters and Surfaces", edited by A.N. Grum-Grzhimailo, E.V. Gryzlova, Yu V. Popov, and A.V. Solov'yov.

  6. Failure Analysis of Heavy-Ion-Irradiated Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Casey, Megan C.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Topper, Alyson D.; Campola, Michael J.; Label, Kenneth A.

    2017-01-01

    In this work, we use high- and low-magnitude optical microscope images, infrared camera images, and scanning electron microscope images to identify and describe the failure locations in heavy-ion-irradiated Schottky diodes.

  7. Structure Change of PTFE by Low Energy Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Watari, Kunio; Iwao, Toru; Yumoto, Motoshige

    The authors irradiate low energy nitrogen ion (100eV) on PTFE (poly-tetra-fluoro-ethylene) for surface modification. However, PTFE cannot anticipate adhesive strength improvement because it is collapse type polymer and weariness of surface occurs by ion irradiation. We paid attention to cross-linked structure to solve this problem. By this study introduce below, PTFE was changed collapse type polymer into cross-linked type polymer by rising temperature above the glass transition in the case of ion irradiation. As a result, the formation of the CF3 combination was restrained and collapse phenomenon was prevented by ion irradiation above the glass transition. In addition, it was suggested that cross-linked structure is effective for adhesive strength improvement by convolution of C1s spectrum and density profile.

  8. Ion irradiation of porous silicon : the role of surface states

    SciTech Connect

    Jacobsohn, L. G.; Bennett, B. L.; Cooke, D. W.; Muenchausen, Ross E.; Nastasi, Michael Anthony,

    2004-01-01

    The summary and conclusions of this paper are: (1) Ion irradiation induces PL quenching from po-Si; (2) Interaction of the implanted ions with defects generated during the irradiation process plays a major role in the PL quenching mechanism; (3) Quenching was associated with the creation of nonradiative states within the gap; and (4) Exposition to air and consequently the oxidation of the surface is shown to enhance PL emission efficiency.

  9. Ion irradiation testing of Improved Accident Tolerant Cladding Materials

    SciTech Connect

    Anderoglu, Osman; Tesmer, Joseph R.; Maloy, Stuart A.

    2014-01-14

    This report summarizes the results of ion irradiations conducted on two FeCrAl alloys (named as ORNL A&B) for improving the accident tolerance of LWR nuclear fuel cladding. After irradiation with 1.5 MeV protons to ~0.5 to ~1 dpa and 300°C nanoindentations were performed on the cross-sections along the ion range. An increase in hardness was observed in both alloys. Microstructural analysis shows radiation induced defects.

  10. Light irradiance and spectral distribution effects on cyanobacterial hydrogen production

    NASA Astrophysics Data System (ADS)

    Fatihah Salleh, Siti; Kamaruddin, Azlina; Hekarl Uzir, Mohamad; Rahman Mohamed, Abdul; Halim Shamsuddin, Abdul

    2016-03-01

    Light is an essential energy source for photosynthetic cyanobacteria. Changes in both light irradiance and spectral distribution will affect their photosynthetic productivity. Compared to the light irradiance, little investigations have been carried out on the effect of light spectra towards cyanobacterial hydrogen production. Hence, this work aims to investigate the effects of both light quantity and quality on biohydrogen productivity of heterocystous cyanobacterium, A.variabilis. Under white light condition, the highest hydrogen production rate of 31 µmol H2 mg chl a -1 h-1 was achieved at 70 µE m-2 s-1. When the experiment was repeated at the same light irradiance but different light spectra of blue, red and green, the accumulations of hydrogen were significantly lower than the white light except for blue light. As the light irradiance was increased to 350 µE m-2 s-1, the accumulated hydrogen under the blue light doubled that of the white light. Besides that, an unusual prolongation of the hydrogen production up to 120 h was observed. The results obtained suggest that blue light could be the most desirable light spectrum for cyanobacterial hydrogen production.

  11. Heavy-ion irradiation induced diamond formation in carbonaceous materials.

    SciTech Connect

    Daulton, T. L.

    1999-01-08

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

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

    SciTech Connect

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

    2012-01-01

    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.

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

    SciTech Connect

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

    2012-09-01

    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.

  14. Edge-on ion irradiation of electron microscope specimens

    SciTech Connect

    Otero, M.P. |; Allen, C.W.

    1992-07-01

    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.

  15. Edge-on ion irradiation of electron microscope specimens

    SciTech Connect

    Otero, M.P. Fundacao de Tecnologia Industrial , Lorena, SP ); Allen, C.W. )

    1992-01-01

    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.

  16. Detection and identification of 1-methylethyl and methyl radicals generated by irradiating tea tree (Melaleuca alternifolia) oil with visible light (436 nm) in the presence of flavin mononucleotide and ferrous ion.

    PubMed

    Mori, H-M; Iwahashi, H

    2013-08-01

    Here, we determined the electron spin resonance (ESR) spectra of standard reaction mixtures (I) containing 25 μM flavin mononucleotide (FMN), 0.018% tea tree (Melaleuca alternifolia) oil, 1.9 M acetonitrile, 20 mM phosphate buffer (pH 7.4), 0.1 M α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN), and 1.0 mM FeSO₄(NH₄)₂SO₄ irradiated with 436 nm visible light (7.8 J/cm²). Prominent ESR signals (αN = 1.58 mT and αHβ = 0.26 mT) were detected, suggesting that free radicals form in the standard reaction. In order to know whether singlet oxygen (¹O₂) is involved in the radical formation or not, ESR measurement was performed for the standard D₂O reaction mixture (I) which contained 25 μM FMN, 0.0036% tea tree oil, 1.9 M acetonitrile-d3, 20 mM phosphate buffer (pH 7.4), 0.1 M 4-POBN and 1.0 mM FeSO₄ in D₂O. The ESR peak height of the standard D₂O reaction increased to 169 ± 24% of the control. Thus, ¹O₂ seems to be involved in the formation of the radicals because D₂O increases the lifetime of singlet oxygen. High-performance liquid chromatography-ESR-mass spectrometry analyses detected 1-methylethyl and methyl radicals in the standard reaction. The radicals appear to form through the reaction of ferrous ion with α-terpinene endoperoxide (ascaridole), which generated from the reaction of α-terpinene with ¹O₂. The 1-methylethyl and methyl radicals may exert a pro-oxidant effect under these conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2006-08-01

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

  18. Morphological study of borosilicate glass surface irradiated by heavy ions

    SciTech Connect

    Wang, T. S.; Du, X.; Yuan, W.; Duan, B. H.; D. Zhang, J.; Chen, L.; Peng, H. B.; Yang, D.; Zhang, G. F.; Zhu, Z. H.

    2016-11-01

    Borosilicate glass is a candidate material for radiation waste formation and other optical applications in various fields. To understand the radiation effect of borosilicate glass, heavy ion (Arq+, Krq+ and Xeq+) irradiations were used to simulate the alpha and recoiled nuclei irradiations in this study. The surface morphology of glass has been compared to ion irradiation doses and ion energies. The surface topography evolution of irradiated samples is characterized by optical microscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS). Micro-bumps are observed on the sample surface after irradiationwith 5 MeV Xeq+ over 5 × 1013 ions·cm-2. The size and density of the bumps increaseswith increasing irradiation dose. At a lowdose, bumps are on the nanometer (nm) scale and rather rare.While the dose is higher than 9 × 1015 ions·cm-2, the size of bumps is on the scale of a few microns, and the density is saturated. However, the height of the bumps increases froma fewnmto over 150nmwith further irradiation. The distribution of micro-bumps is nearly homogeneous. The bumps are condensed and swell up, and there is no crystallized structure according to the TEMdiffraction pattern. Elementmigration and concentrations are observedwith SIMS imaging. The arrayed micro-bumps are a new finding, and they might be used to change the surface properties. Bump formation is caused by phase separation, and volume swelling is induced by ion irradiation.

  19. Photosynthetic Effect in Selenastrum capricornutum Progeny after Carbon-Ion Irradiation.

    PubMed

    Wang, Jie; Li, Xin; Lu, Dong; Du, Yan; Ma, Liang; Li, Wenjian; Chen, Jihong; Li, Fuli; Fan, Yong; Hu, Guangrong; Wang, Jufang

    2016-01-01

    A large proportion of mutants with altered pigment features have been obtained via exposure to heavy-ion beams, a technique that is efficient for trait improvement in the breeding of plants and algae. However, little is known about the underlying mechanisms by which the photosynthetic pigments are altered by heavy-ion irradiation. In our study, the photosynthetic characteristics of progenies from carbon-ion irradiated Selenastrum capricornutum were investigated. Five progenies deficient in chlorophyll a were isolated after carbon-ion exposure. Photosynthetic characteristics, photoprotection capacity and gene expression of the light-harvesting complex in these progenies were further characterized by the measurement of chlorophyll fluorescence parameters (Fv/Fm, ФPSII, NPQ, ETR), the de-epoxidation state of the xanthophyll cycle, the amount of lutein and quantitative real-time PCR. High maximum quantum yield of photosystem II at day 10 and high thermal dissipation ability were observed in progenies #23 and #37 under normal culture condition. Progenies #18, #19 and #20 showed stronger resistance against high levels of light steps than the control group (612-1077 μmol photons m -2 s -1, p< 0.05). The progenies #20 and #23 exhibited strong photoprotection by thermal dissipation and quenching of 3Chl* after 24 h of high light treatment. The mRNA levels of Lhcb5, Lhcbm5 and Lhcbm1 of the light-harvesting complex revealed markedly differential expression in the five progenies irradiated by carbon-ion beams. This work indicates that photosynthetic efficiency, photoprotection ability and the expression of light-harvesting antennae in unicellular green algae can be markedly influenced by irradiation. To our knowledge, this is the first report on changes in the photosynthetic pigments of green algae after treatment with carbon-ion beams.

  20. Photosynthetic Effect in Selenastrum capricornutum Progeny after Carbon-Ion Irradiation

    PubMed Central

    Wang, Jie; Li, Xin; Lu, Dong; Du, Yan; Ma, Liang; Li, Wenjian; Chen, Jihong; Li, Fuli; Fan, Yong; Hu, Guangrong; Wang, Jufang

    2016-01-01

    A large proportion of mutants with altered pigment features have been obtained via exposure to heavy-ion beams, a technique that is efficient for trait improvement in the breeding of plants and algae. However, little is known about the underlying mechanisms by which the photosynthetic pigments are altered by heavy-ion irradiation. In our study, the photosynthetic characteristics of progenies from carbon-ion irradiated Selenastrum capricornutum were investigated. Five progenies deficient in chlorophyll a were isolated after carbon-ion exposure. Photosynthetic characteristics, photoprotection capacity and gene expression of the light-harvesting complex in these progenies were further characterized by the measurement of chlorophyll fluorescence parameters (Fv/Fm, ФPSII, NPQ, ETR), the de-epoxidation state of the xanthophyll cycle, the amount of lutein and quantitative real-time PCR. High maximum quantum yield of photosystem II at day 10 and high thermal dissipation ability were observed in progenies #23 and #37 under normal culture condition. Progenies #18, #19 and #20 showed stronger resistance against high levels of light steps than the control group (612–1077 μmol photons m -2 s -1, p< 0.05). The progenies #20 and #23 exhibited strong photoprotection by thermal dissipation and quenching of 3Chl* after 24 h of high light treatment. The mRNA levels of Lhcb5, Lhcbm5 and Lhcbm1 of the light-harvesting complex revealed markedly differential expression in the five progenies irradiated by carbon-ion beams. This work indicates that photosynthetic efficiency, photoprotection ability and the expression of light-harvesting antennae in unicellular green algae can be markedly influenced by irradiation. To our knowledge, this is the first report on changes in the photosynthetic pigments of green algae after treatment with carbon-ion beams. PMID:26919351

  1. Iron release analyses from ferritin by visible light irradiation.

    PubMed

    Ohishi, Kentaro; Zhang, Xiao Mei; Moriwaki, Shinichi; Hiramitsu, Tadahisa; Matsugo, Seiichi

    2005-08-01

    We investigated the iron release from ferritin by irradiation from a white fluorescent light in the absence or presence of ADP. Irradiation of a ferritin solution at 17,000 lx in the absence of ADP slightly induces iron release from ferritin but only at acidic pH conditions (pH 5.0 or pH 6.0). Irradiation in the presence of ADP markedly enhances iron release from ferritin under the same conditions. In the absence of irradiation, the iron release from ferritin was low even in the presence of ADP. The induction of the iron release by irradiation in the presence of ADP was also affected by various factors such as irradiation dose and acidity, but not temperature (4-47 degrees C), oxygen concentration, or free radical generations during the irradiation. The iron release during the irradiation ceased to increase by turning off the light and was found to increase again after additional irradiation. These results suggest that visible light directly induces iron release from ferritin via the photoreduction of iron stored inside ferritin.

  2. Light irradiation helps magnetotactic bacteria eliminate intracellular reactive oxygen species.

    PubMed

    Li, Kefeng; Wang, Pingping; Chen, Chuanfang; Chen, Changyou; Li, Lulu; Song, Tao

    2017-09-01

    Magnetotactic bacteria (MTB) demonstrate photoresponse. However, little is known about the biological significance of this behaviour. Magnetosomes exhibit peroxidase-like activity and can scavenge reactive oxygen species (ROS). Magnetosomes extracted from the Magnetospirillum magneticum strain AMB-1 show enhanced peroxidase-like activity under illumination. The present study investigated the effects of light irradiation on nonmagnetic (without magnetosomes) and magnetic (with magnetosomes) AMB-1 cells. Results showed that light irradiation did not affect the growth of nonmagnetic and magnetic cells but significantly increased magnetosome synthesis and reduced intracellular ROS level in magnetic cells. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to analyse the expression level of magnetosome formation-associated genes (mamA, mms6, mms13 and mmsF) and stress-related genes (recA, oxyR, SOD, amb0664 and amb2684). Results showed that light irradiation upregulated the expression of mms6, mms13 and mmsF. Furthermore, light irradiation upregulated the expression of stress-related genes in nonmagnetic cells but downregulated them in magnetic cells. Additionally, magnetic cells exhibited stronger phototactic behaviour than nonmagnetic ones. These results suggested that light irradiation could heighten the ability of MTB to eliminate intracellular ROS and help them adapt to lighted environments. This phenomenon may be related to the enhanced peroxidase-like activity of magnetosomes under light irradiation. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Anomalous Plastic Deformation and Sputtering of Ion Irradiated Silicon Nanowires

    PubMed Central

    2015-01-01

    Silicon nanowires of various diameters were irradiated with 100 keV and 300 keV Ar+ ions on a rotatable and heatable stage. Irradiation at elevated temperatures above 300 °C retains the geometry of the nanostructure and sputtering can be gauged accurately. The diameter dependence of the sputtering shows a maximum if the ion range matches the nanowire diameter, which is in good agreement with Monte Carlo simulations based on binary collisions. Nanowires irradiated at room temperature, however, amorphize and deform plastically. So far, plastic deformation has not been observed in bulk silicon at such low ion energies. The magnitude and direction of the deformation is independent of the ion-beam direction and cannot be explained with mass-transport in a binary collision cascade but only by collective movement of atoms in the collision cascade with the given boundary conditions of a high surface to volume ratio. PMID:25951108

  4. Anomalous Plastic Deformation and Sputtering of Ion Irradiated Silicon Nanowires.

    PubMed

    Johannes, Andreas; Noack, Stefan; Wesch, Werner; Glaser, Markus; Lugstein, Alois; Ronning, Carsten

    2015-06-10

    Silicon nanowires of various diameters were irradiated with 100 keV and 300 keV Ar(+) ions on a rotatable and heatable stage. Irradiation at elevated temperatures above 300 °C retains the geometry of the nanostructure and sputtering can be gauged accurately. The diameter dependence of the sputtering shows a maximum if the ion range matches the nanowire diameter, which is in good agreement with Monte Carlo simulations based on binary collisions. Nanowires irradiated at room temperature, however, amorphize and deform plastically. So far, plastic deformation has not been observed in bulk silicon at such low ion energies. The magnitude and direction of the deformation is independent of the ion-beam direction and cannot be explained with mass-transport in a binary collision cascade but only by collective movement of atoms in the collision cascade with the given boundary conditions of a high surface to volume ratio.

  5. Luminescence imaging of water during carbon-ion irradiation for range estimation

    SciTech Connect

    Yamamoto, Seiichi Komori, Masataka; Koyama, Shuji; Morishita, Yuki; Sekihara, Eri; Akagi, Takashi; Yamashita, Tomohiro; Toshito, Toshiyuki

    2016-05-15

    Purpose: The authors previously reported successful luminescence imaging of water during proton irradiation and its application to range estimation. However, since the feasibility of this approach for carbon-ion irradiation remained unclear, the authors conducted luminescence imaging during carbon-ion irradiation and estimated the ranges. Methods: The authors placed a pure-water phantom on the patient couch of a carbon-ion therapy system and measured the luminescence images with a high-sensitivity, cooled charge-coupled device camera during carbon-ion irradiation. The authors also carried out imaging of three types of phantoms (tap-water, an acrylic block, and a plastic scintillator) and compared their intensities and distributions with those of a phantom containing pure-water. Results: The luminescence images of pure-water phantoms during carbon-ion irradiation showed clear Bragg peaks, and the measured carbon-ion ranges from the images were almost the same as those obtained by simulation. The image of the tap-water phantom showed almost the same distribution as that of the pure-water phantom. The acrylic block phantom’s luminescence image produced seven times higher luminescence and had a 13% shorter range than that of the water phantoms; the range with the acrylic phantom generally matched the calculated value. The plastic scintillator showed ∼15 000 times higher light than that of water. Conclusions: Luminescence imaging during carbon-ion irradiation of water is not only possible but also a promising method for range estimation in carbon-ion therapy.

  6. Synchronization of oscillatory chemiluminescence with pulsed light irradiation

    NASA Astrophysics Data System (ADS)

    Takayama, Shunsuke; Okano, Kunihiko; Asakura, Kouichi

    2013-01-01

    A chemical oscillator, the H2O2-KSCN-CuSO4-NaOH system, generates an oscillatory chemiluminescence when luminol is added to this system. Attempts were made to synchronize the oscillatory chemiluminescence with pulsed light irradiation. A period of the chemical oscillation became shorter by the irradiation of white and blue color light, while the oscillatory behavior was scarcely influenced by the irradiation of red light. Pulsed red and white or blue lights were irradiated on either the non-luminol or luminol-added H2O2-KSCN-CuSO4-NaOH system. Synchronization of the chemical oscillation was achieved for 25-30 min in the luminol-added system.

  7. Irradiation effects of displacement damage and gas atoms in Yttria-stabilized zirconia irradiated by Au and helium ions

    NASA Astrophysics Data System (ADS)

    Zhang, Yanwen; Zhao, Ziqiang; Guo, Gang

    2017-07-01

    Single and sequential ion beam irradiated Yttria-stabilized zirconia (YSZ) was carried out to study the irradiation effects of vacancies and helium gas atoms. The results show that the displacement damage value of sequential ion beam irradiation is less than that of single He ion irradiation and larger than that of single Au ion irradiation. The irradiation effects of displacement damage (mainly vacancies) and gas atoms may lead to a strong reduction of the interstitial helium atoms. Sequential ion beam irradiation generates more vacancies-helium bubbles than single helium ion irradiation. The results are important for fundamental understanding of interaction between vacancy and helium bubbles, and it also plays a guiding role in the practical industrial applications in the nuclear reactor.

  8. Nonimaging light concentrator with uniform irradiance

    DOEpatents

    Winston, Roland; Gee, Randy C.

    2003-04-01

    A nonimaging light concentrator system including a primary collector of light, an optical mixer disposed near the focal zone for collecting light from the primary collector, the optical mixer having a transparent entrance aperture, an internally reflective housing for substantially total internal reflection of light, a transparent exit aperture and an array of photovoltaic cells disposed near the transparent exit aperture.

  9. Transport of Light Ions in Matter

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Cucinotta, F. A.; Tai, H.; Shinn, J. L.; Chun, S. Y.; Tripathi, R. K.; Sihver, L.

    1998-01-01

    A recent set of light ion experiments are analyzed using the Green's function method of solving the Boltzmann equation for ions of high charge and energy (the GRNTRN transport code) and the NUCFRG2 fragmentation database generator code. Although the NUCFRG2 code reasonably represents the fragmentation of heavy ions, the effects of light ion fragmentation requires a more detailed nuclear model including shell structure and short range correlations appearing as tightly bound clusters in the light ion nucleus. The most recent NTJCFRG2 code is augmented with a quasielastic alpha knockout model and semiempirical adjustments (up to 30 percent in charge removal) in the fragmentation process allowing reasonable agreement with the experiments to be obtained. A final resolution of the appropriate cross sections must await the full development of a coupled channel reaction model in which shell structure and clustering can be accurately evaluated.

  10. Forsterite amorphisation by ion irradiation: Monitoring by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Brucato, J. R.; Strazzulla, G.; Baratta, G.; Colangeli, L.

    2004-01-01

    We present experimental results on the crystal-amorphous transition of forsterite (Mg2SiO4) silicate under ion irradiation. The aim of this work is to study the structural evolution of one of the most abundant crystalline silicates observed in space driven by ion irradiation. To this aim, forsterite films have been synthesised in the laboratory and irradiated with low energy (30-60 keV) ion beams. Structural changes during irradiation with H+, He+, C+, and Ar++ have been observed and monitored by infrared spectroscopy. The fraction of crystalline forsterite converted into the amorphous form is a function of the energy deposited by nuclear collision by ions in the target. Laboratory results indicate that ion irradiation is a mechanism potentially active in space for the amorphisation of silicates. Physical properties obtained in this work can be used to model the evolution of silicate grains during their life cycle from evolved stars, through different interstellar environments and up to being incorporated in Solar System objects.

  11. Data acquisition for the HILI (Heavy Ion Light Ion) detector

    SciTech Connect

    Teh, K.M.; Shapira, D.; McConnell, J.W.; Kim, H.; Novotny, R.

    1987-01-01

    A large acceptance, multi-segmented detector system capable of the simultaneous detection of heavy and light ions has been constructed. The heavy ions are detected with a segmented gas ionization chamber and a multiwire proportional counter while the light ions are detected with a 192 element plastic phoswich hodoscope. Processing the large number of signals is accomplished through a combination of CAMAC and FASTBUS modules and preprocessors, and a Host minicomputer. Details of the data acquisition system and the reasons for adopting a dual standards system are discussed. In addition, a technique for processing signals from an individual hodoscope detector is presented. 4 refs., 3 figs.

  12. High-intensity sources for light ions

    SciTech Connect

    Leung, K.N.

    1995-10-01

    The use of the multicusp plasma generator as a source of light ions is described. By employing radio-frequency induction discharge, the performance of the multicusp source is greatly improved, both in lifetime and in high brightness H{sup +} and H{sup {minus}} beam production. A new technique for generating multiply-charged ions in this type of ion source is also presented.

  13. Raman measurements in silica glasses irradiated with energetic ions

    SciTech Connect

    Saavedra, R. Martin, P.; Vila, R.; León, M.; Jiménez-Rey, D.; Girard, S.; Boukenter, A.; Ouerdane, Y.

    2014-10-21

    Ion irradiation with energetic He{sup +} (2.5 MeV), O{sup 4+} (13.5 MeV), Si{sup 4+} (24.4 MeV) and Cu{sup 7+} (32.6 MeV) species at several fluences (from 5 × 10{sup 12} to 1.65 × 10{sup 15} ion/cm{sup 2}) were performed in three types of SiO{sub 2} glasses with different OH content (KU1, KS-4V and Infrasil 301). After ion implantation the Raman spectra were measured and compared with the spectra of unirradiated samples. Irradiated samples of the three fused silica grades exhibit changes in the broad and asymmetric R-band (ω{sub 1} around 445 cm{sup −1}), in D{sub 1} (490 cm−1) and D{sub 2} (605 cm{sup −1}) bands associated to small-membered rings. The D{sub 2} band shows an increase with increasing fluences for different ions, indicating structural changes. Raman spectra of ion-irradiated samples were compared with the spectra of neutron irradiated samples at fluences 10{sup 17} n/cm{sup 2} and 1018 n/cm{sup 2}. Macroscopic surface cracking was detected, mainly at fluences corresponding to deposited energies between 10{sup 23} eV/cm{sup 3} and 10{sup 24} eV/cm{sup 3} (after ion beam shutdown)

  14. Folding two dimensional crystals by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Ochedowski, Oliver; Bukowska, Hanna; Freire Soler, Victor M.; Brökers, Lara; Ban-d'Etat, Brigitte; Lebius, Henning; Schleberger, Marika

    2014-12-01

    Ion irradiation of graphene, the showcase model of two dimensional crystals, has been successfully applied to induce various modifications in the graphene crystal. One of these modifications is the formation of origami like foldings in graphene which are created by swift heavy ion irradiation under glancing incidence angle. These foldings can be applied to locally alter the physical properties of graphene like mechanical strength or chemical reactivity. In this work we show that the formation of foldings in two dimensional crystals is not restricted to graphene but can be applied for other materials like MoS2 and hexagonal BN as well. Further we show that chemical vapour deposited graphene forms foldings after swift heavy ion irradiation while chemical vapour deposited MoS2 does not.

  15. Ion irradiation of ices: astrochemical and astrobiological applications.

    NASA Astrophysics Data System (ADS)

    Strazzulla, G.; Brucato, J. R.; Palumbo, M. E.; Spinella, F.

    We present some recent results obtained by an ongoing research that aims into the experimental study of the effects induced by fast ions in solids, in particular frozen gases. The technique used to analyze the effects of irradiation has been "in situ" infrared spectroscopy. Here we discuss the formation of carbon chain oxides (e.g. C_3O_2) after ion irradiation of frozen CO. A detailed study of the IR spectroscopic properties of solid frozen formamide is presented along with the modifications induced by ion irradiation. The results are relevant to explain the presence of molecules in the circumstellar environment of a newly born star. Those molecules could be produced by energetic processing of dust and released to the gas phase after warming up.

  16. Reduction and structural modification of zirconolite on He+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Gupta, Merry; Kulriya, P. K.; Shukla, Rishabh; Dhaka, R. S.; Kumar, Raj; Ghumman, S. S.

    2016-07-01

    The immobilization of minor actinides and alkaline-earth metal is a major concern in nuclear industry due to their long-term radioactive contribution to the high level waste (HLW). Materials having zirconolite, pyrochlore, and perovskite structure are promising candidates for immobilization of HLW. The zirconolite which exhibits high radiation stability and corrosion resistance behavior is investigated for its radiation stability against alpha particles in the present study. CaZrTi2O7 pellets prepared using solid state reaction techniques, were irradiated with 30 keV He+ ions for the ion fluence varying from 1 × 1017 to 1 × 1021 ions/m2. Scanning electron microscopy (SEM) images of the un-irradiated sample exhibited well separated grains with average size of about 6.8 μm. On the ion irradiation, value of the average grains size was about 7.1 μm, and change in the microstructure was insignificant. The X-ray photoelectron spectroscopy (XPS) studies showed a shift in the core level peak position (of Ca 2p, Ti 2p and Zr 3d) towards lower binding energy with respect to pristine sample as well as loss of oxygen was also observed for sample irradiated with the ion fluence of 1 × 1020 ions/m2. These indicate a decrease in co-ordination number and the ionic character of Msbnd O bond. Moreover, core level XPS signal was not detected for sample irradiated with ion fluence of 1 × 1021 ions/m2, suggesting surface damage of the sample at this ion fluence. However, X-ray diffraction (XRD) studies showed that zirconolite was not amorphized even on irradiation up to a fluence order of 1 × 1021 ion/m2. But, significant decrease in peak intensity due to creation of defects and a marginal positive peak shift due to tensile strain induced by irradiation, were observed. Thus, XRD along with XPS investigation suggests that reduction, decrease in co-ordination number, and increase in covalency are responsible for the radiation damage in zirconolite.

  17. Surface modification of multilayer graphene using Ga ion irradiation

    SciTech Connect

    Wang, Quan; Shao, Ying; Ge, Daohan; Ren, Naifei; Yang, Qizhi

    2015-04-28

    The effect of Ga ion irradiation intensity on the surface of multilayer graphene was examined. Using Raman spectroscopy, we determined that the irradiation caused defects in the crystal structure of graphene. The density of defects increased with the increase in dwell times. Furthermore, the strain induced by the irradiation changed the crystallite size and the distance between defects. These defects had the effect of doping the multilayer graphene and increasing its work function. The increase in work function was determined using contact potential difference measurements. The surface morphology of the multilayer graphene changed following irradiation as determined by atomic force microscopy. Additionally, the adhesion between the atomic force microscopy tip and sample increased further indicating that the irradiation had caused surface modification, important for devices that incorporate graphene.

  18. Ion irradiation of TNO surface analogue ice mixtures: the chemistry .

    NASA Astrophysics Data System (ADS)

    Baratta, G. A.; Brunetto, R.; Caniglia, G.; Fulvio, D.; Ioppolo, S.; Leto, G.; Palumbo, M. E.; Spinella, F.; Strazzulla, G.

    Vis-NIR spectra of some Centaurs and Trans-Neptunian Objects (TNOs) indicate surfaces rich in H_2O, N_2, CO_2, CH_4 e CH_3OH. Cosmic ion irradiation is one of the processes driving the evolution of TNO surfaces. A main role is played by the chemistry induced by colliding ions; many molecular bonds are broken along the ion track, and this may lead to the formation of byproduct molecules. Starting from laboratory experiments, it is possible to infer the presence of molecules still undetected on TNOs. For instance, carbonic acid (H_2CO_3) is produced after irradiation of H_2O:CO_2 icy mixtures, while irradiation of H_2O:N_2 icy mixtures causes the production of N_2O, NO, and NO_2. From H_2O:CH_4:N_2 mixtures, many species are formed, such as CO, CO_2, HCN, HNCO, N_2O, and molecules including CN bonds. Moreover, ion irradiation may modify the relative intensity of NIR features, as in the case of solid methanol, whose 2.34 mu m band decreases in intensity with respect to the 2.27 mu m band, after increasing irradiation doses. We suggest that this effect may be observed on Centaur Pholus.

  19. Structural evolution of zirconium carbide under ion irradiation

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

  20. Improvement in Adhesive Strength of PTFE using Nitrogen Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Watanabe, Tsuyoshi; Iwao, Toru; Yumoto, Motoshige

    The adhesive strength doesn't improve so much even if the surface is activated. It is known that PTFE (polytetra fluoroethylene) is one of the collapse type polymer since the binding energy of main chain is smaller than that of side chain. Accordingly, it is assumed that adhesive strength may improve by suppressing the collapse of structure. It is also expected that introduction of cross-linking structure may suppress the collapse of structure. It was confirmed that a lot of polar radicals were introduced at the surface by nitrogen ion irradiation around 30 eV. Thus, to introduce the cross-linking structure several 100 eV nitrogen ions were irradiated after irradiation of nitrogen with 30 eV ion. As a result, adhesive strength irradiated by 300 eV improved more than that of 1000 eV. From the result of XPS (X-ray-Photoelectron-Spectroscopy) analysis, many C-N-C bonds contributing cross-linking structure was detected at a shallow layer by irradiation of ions with 300 eV. From these results, it is concluded that the depth of cross-link formation is important to improve the adhesive strength.

  1. Crystalline nanostructures on Ge surfaces induced by ion irradiation

    NASA Astrophysics Data System (ADS)

    Ou, Xin; Facsko, Stefan

    2014-12-01

    Besides conventional low efficiency lithographic techniques broad ion beam irradiation is a simple and potentially mass productive technique to fabricate nanoscale patterns on various semiconductor surfaces. The main drawback of this method is that the irradiated semiconductor surfaces are amorphized, which strongly limits the potential application of these nanostructures in electronic and optoelectronic devices. In this work we report that high-quality crystalline nanostructure patterns are formed on Ge surfaces via Ar+ irradiation at elevated temperatures. This pattern formation process resembles the pattern formation in homoepitaxy. Therefore, the process is discussed based on a 'reverse epitaxy' mechanism.

  2. CHALLENGES OF COMBINED SEWER OVERFLOW DISINFECTION BY ULTRAVIOLET LIGHT IRRADIATION

    EPA Science Inventory

    This article examines the performance and effectiveness of ultraviolet (UV) light irradiation for disinfection of combined sewer overflow (CSO). Due to the negative impact of conventional water disinfectants on aquatic life, new agents (e.g., UV light) are being investigated for ...

  3. FTIR study of silicon carbide amorphization by heavy ion irradiations

    NASA Astrophysics Data System (ADS)

    Costantini, Jean-Marc; Miro, Sandrine; Pluchery, Olivier

    2017-03-01

    We have measured at room temperature (RT) the Fourier-transform infra-red (FTIR) absorption spectra of ion-irradiated thin epitaxial films of cubic silicon carbide (3C-SiC) with 1.1 µm thickness on a 500 µm thick (1 0 0) silicon wafer substrate. Irradiations were carried out at RT with 2.3 MeV 28Si+ ions and 3.0 MeV 84Kr+ ions for various fluences in order to induce amorphization of the SiC film. Ion projected ranges were adjusted to be slightly larger than the film thickness so that the whole SiC layers were homogeneously damaged. FTIR spectra of virgin and irradiated samples were recorded for various incidence angles from normal incidence to Brewster’s angle. We show that the amorphization process in ion-irradiated 3C-SiC films can be monitored non-destructively by FTIR absorption spectroscopy without any major interference of the substrate. The compared evolutions of TO and LO peaks upon ion irradiation yield valuable information on the damage process. Complementary test experiments were also performed on virgin silicon nitride (Si3N4) self-standing films for similar conditions. Asymmetrical shapes were found for TO peaks of SiC, whereas Gaussian profiles are found for LO peaks. Skewed Gaussian profiles, with a standard deviation depending on wave number, were used to fit asymmetrical peaks for both materials. A new methodology for following the amorphization process is proposed on the basis of the evolution of fitted IR absorption peak parameters with ion fluence. Results are discussed with respect to Rutherford backscattering spectrometry channeling and Raman spectroscopy analysis.

  4. Sputtering of metals at ion-electron irradiation

    NASA Astrophysics Data System (ADS)

    Martynenko, Yu. V.; Korshunov, S. N.; Skorlupkin, I. D.

    2014-02-01

    It has been found that, in contrast to the commonly accepted opinion, simultaneous irradiation by 15-keV Ar+ ions and 2.5-keV electrons at temperatures above 0.5 T m ( T m is the melting temperature) induces much larger sputtering of metallic copper, nickel, and steel than irradiation only by Ar+ ions. The effect increases with the temperature. At T = 0.7 T m, the sputtering coefficients in the case of ion-electron irradiation are more than twice as large as the sputtering coefficients in the case of irradiation by Ar+ ions. The experiments on the sublimation of copper show that the sublimation rate in the case of the heating of a sample by an electron beam is higher than that in the case of heating in an electric vacuum oven. The revealed effects are explained by the electron-induced excitation of adatoms (atoms stuck over the surface, which appear owing to ion bombardment). Excited adatoms have a smaller binding energy with the surface and are sputtered more easily.

  5. Plant Growth Under Light Emitting Diode Irradiation.

    NASA Astrophysics Data System (ADS)

    Tennessen, Daniel John

    Plant growth under light emitting diodes (LEDs) was investigated to determine if LEDs would be useful to provide radiant energy for two plant processes, photosynthesis and photomorphogenesis. Photosynthesis of tomato (Lycopersicon esculentum L.) and Kudzu (Pueraria lobata (Willd) Ohwi.) was measured using photons from LEDs to answer the following: (1) Are leaves able to use red LED light for photosynthesis? and (2) Is the efficiency of photosynthesis in pulsed light equal to that of continuous light? In 175 Pa CO _2, or in response to changes in CO _2,<=af photosynthesis and ATP status were the same in LED as in white xenon arc light. In 35 Pa CO_2, photosynthesis was 10% lower in LED than in xenon arc light due to lowered stomatal conductance. The quantum efficiency of photosynthesis in pulsed light was equal to continuous light, even when pulses were twice as bright as sunlight. Xanthophyll pigments were not affected by these bright pulses. Photomorphogenesis of tobacco (Nicotiana tabacum L.), tomato (Lycopersicon esculentum Mill.) and transformed tobacco and tomato (expressing oat phytochrome-A) was assessed by growing plants under red LED lamps in an attempt to answer the following: (1) What is the developmental response of non-transformed and transformed tobacco to red LED light? and (2) Can tomato plants that grow tall and spindly in red LED light be made to grow short by increasing the amount of phytochrome-A? The short phenotype of transformed tobacco was not evident when plants were grown in LED light. Addition of photons of far-red or blue light to red light resulted in short transformed tobacco. Tomato plants grew three times as tall and lacked leaf development in LED versus white light, but transformed tomato remained short and produced fruit under LED light. I have determined that the LED photons are useful for photosynthesis and that the photon efficiency of photosynthesis is the same in pulsed as in continuous light. From responses of tobacco, I

  6. Electron Irradiation of Light Emitting Diodes.

    DTIC Science & Technology

    1984-12-01

    the present experiment were fabricated by liquid phase epitaxy (LPE) or vapor phase epitaxy (VPE). Millea and Aukerman [Ref. 5 and 6] studied electron...neutron induced damage. They and Millea and Aukerman [Ref. 6] observed the absence of bias induced recovery in neutron irradiated LEDs. This is in...Herrick, D., J. Applied Phys., 41, 3783, 1970. 4. Stanley, A.G., IEEE Trans. Nucl. Sci., NS-17, 239, 1970. 5. Millea, M.F., and Aukerman , L.W., J

  7. Formation of dislocations and hardening of LiF crystals irradiated with energetic Au, Bi, Pb, and S ions

    NASA Astrophysics Data System (ADS)

    Maniks, J.; Manika, Ilze; Schwartz, K.; Toulemonde, M.; Trautmann, C.

    2003-08-01

    The irradiation of LiF crystals with Au, Pb, Bi, and S ions in the range of 400 - 2200 MeV leads to a remarkable increase of the hardness. The effect appears for Bi and Pb ions at fluences above 109 ions/cm2 and for S ions above 1010 ions/cm2. The increase of hardness follows the energy loss and is related to the formation of defects along the ion path. Defect complexes, clusters and aggregates with nanoscale dimensions serve as strong obstacles for dislocations and cause dispersion strengthening. Structural investigations reveal the generation of long-range stress in the adjacent non-irradiated part of the crystal. Close to the implantation zone, the stress exceeds the yield strength, causing microplastic deformation and work hardening. Compared to light S ions, heavy ions (Au, Pb, Bi) cause more severe structural damage, larger hardening effects, and higher internal and long-range stress.

  8. The effect of red light irradiation on spermatozoa DNA

    NASA Astrophysics Data System (ADS)

    Chow, Kay W.; Preece, Daryl; Gomez-Godinez, Veronica; Berns, Michael W.

    2016-09-01

    A key goal in the conservation of endangered species is to increase successful reproduction. In cases where traditional methods of in vitro fertilization are unsuccessful, new methods of assisted reproduction are needed. One option is selective fertilization via optically trapped sperm. A more passive option is red light irradiation. Red light irradiation has been shown to increase sperm motility, thus increasing fertilizing potential. However, there is some concern that exposure to laser irradiation induces the production of oxidative species in cells, which can be damaging to DNA. In order to test the safety of irradiating sperm, sperm samples were exposed to 633 nm laser light and their DNA were tested for oxidative damage. Using fluorescence microscopy, antibody staining, and ELISA to detect oxidative DNA damage, it was concluded that red light irradiation does not pose a safety risk to sperm DNA. The use of red light on sperm has potential in both animal conservation and human reproduction techniques. This method can also be used in conjunction with optical trapping for viable sperm selection.

  9. Ion irradiation induced impurity redistribution in Pt/C multilayers

    NASA Astrophysics Data System (ADS)

    Bera, S.; Goswami, D. K.; Bhattacharjee, K.; Dev, B. N.; Kuri, G.; Nomoto, K.; Yamashita, K.

    2003-12-01

    Ion irradiation induced modifications of a periodic Pt/C multilayer system containing Fe impurity have been analyzed by X-ray techniques suitable for exploring nanometer depth scales with sub-nanometer depth resolution. The multilayer stack with 15 Pt/C layer pairs (period 4.23 nm, total thickness 63.45 nm) was fabricated on a glass substrate. A 2 MeV Au 2+ ion beam was rastered on the sample to obtain uniformly irradiated strips with fluences from 1 × 10 14 to 1 × 10 15 ions/cm 2. These strips were analyzed with X-ray standing wave and X-ray reflectivity experiments. Ion induced atomic displacements across multilayer interfaces are known [Appl. Phys. Lett. 79 (2001) 467]. Here additionally we identify irradiation induced redistribution of Fe impurity atoms, which cannot be explained simply by atomic displacements due to ion-atom collision. With increasing ion fluences more Fe atoms migrate from C- to Pt-layers. This behaviour has been explained in terms of radiation induced enhanced diffusion and Fe-Pt and Fe-C phase diagrams.

  10. Tailoring the properties of copper nanowires by ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Kumar, Narinder; Kumar, Rajesh; Kumar, Sushil; Chakarvarti, S. K.

    2016-02-01

    In the present paper, we investigated the change in the properties of copper nanowires under the irradiance of 80 MeV Si7+ ion beam. The nanowires were electrodeposited in the cylindrical pores of the track-etched polycarbonate membranes. The phase, morphology and optical absorbance of the fabricated nanowires were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy, respectively. The XRD study showed a face centered cubic crystal structure of copper nanowires. Further measurements with FESEM revealed that nanowires were continuous, aligned with uniform diameter having high aspect ratio. The XRD spectra of irradiated nanowires indicated an improved crystalinity at low ion fluences while it declines at higher ion fluences. The optical absorbance properties of the irradiated copper nanowires were also examined. The absorption spectra exhibited a peak at 568 nm which was attributed to the surface plasmon resonance. A significant increase in absorbance after irradiation accounts for the possibility of defects formation. The electrical properties measured from I-V characteristics showed an increase in resistivity of irradiated nanowires.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  12. Zirconium oxidation under high-energy heavy-ion irradiation

    SciTech Connect

    Bererd, N.; Chevarier, A.; Moncoffre, N.; Jaffrezic, H.; Balanzat, E.; Catalette, H.

    2005-04-15

    This paper concerns the study of zirconium oxidation under irradiation with high energetic Xe ions. The irradiations were performed on the IRRadiation SUD (IRRSUD) beam line at Grand Accelerateur National d'Ions Lourds of Caen. The oxygen partial pressure was fixed at 10{sup -3} Pa and two temperature conditions were used, either 480 deg. C reached by Joule effect heating or 280 deg. C due to Xe energy deposition. Zirconia was fully characterized by Rutherford backscattering spectrometry, scanning electron microscopy, and grazing angle x-ray diffraction. Apparent diffusion coefficients of oxygen in ZrO{sub 2} were determined from these experiments by using a model which takes into account a surface exchange between oxygen gas and the ZrO{sub 2} surface. These results are compared with thermal oxidation data.

  13. Laser irradiations of advanced targets promoting absorption resonance for ion acceleration in TNSA regime

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Calcagno, L.; Giulietti, D.; Cutroneo, M.; Zimbone, M.; Skala, J.

    2015-07-01

    Advanced targets based on Au nanoparticles embedded in polymers films show high absorption coefficient in the UV-visible and infrared region. They can be employed to enhance the proton and ion acceleration from the laser-generated plasma in TNSA regime. In conditions of "p" polarized laser irradiations at 1015 W/cm2 intensity, in these films can be induced resonant absorption due to plasma wave excitation. Plasma on-line diagnostics is based on SiC detectors, Thomson spectrometry and X-ray streak camera imaging. Measurements of kinetic energy of accelerated ions indicate a significant increment using polymer targets containing gold nanoparticles and "p" polarized laser light with respect to pure polymers and unpolarized light irradiation.

  14. Effect of linear polarized near-infrared light irradiation and light exercise on muscle performance.

    PubMed

    Demura, Tomohiro; Demura, Shinichi; Aoki, Hiroki; Uchida, Yuu; Yamaji, Shunsuke

    2011-01-01

    This study aimed to determine the effect of active warm-up by local muscle light exercise and passive warm-up by polarized light irradiation on skin and muscle temperatures and forearm muscle performance (muscle strength, power, endurance, and controlled force-exertion). Ten healthy males performed various grip tests before and after active (local muscle light exercise) and passive (linear polarized near-infrared light irradiation) warm-ups. An active warm-up involved intermittent gripping exercise (contraction: 1 second and relaxation: 1 second) for 10 minutes using a sponge. A passive warm-up consisted of polarized light irradiation to the forearm (superficial digital flexor) for 10 minutes (irradiation: 5 seconds and rest: 1 second). Skin and muscle temperatures were measured during both warm-ups. Skin and muscle temperatures increased significantly after 5 minutes of local muscle light exercise and after 10 minutes of polarized light irradiation. Temperatures were significantly higher after 6 minutes of local muscle light exercise than after 6 minutes of polarized light irradiation. There were no significant differences of muscle strength, power, and controlled force-exertion before and after either warm-up. Average force outputs in all conditions significantly decreased with exertion time, and at 30, 60, 90, and 120 seconds they were higher in both warm-up conditions than in the non-warm-up condition. In conclusion, both warm-ups may contribute to improve muscle endurance performance in the decreasing force phase.

  15. Effects of Ga ion-beam irradiation on monolayer graphene

    SciTech Connect

    Wang, Quan; Mao, Wei; Zhang, Yanmin; Shao, Ying; Ren, Naifei; Ge, Daohan

    2013-08-12

    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.

  16. Ion beam irradiated optical channel waveguides

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  17. Irradiation With Carbon Ion Beams Induces Apoptosis, Autophagy, and Cellular Senescence in a Human Glioma-Derived Cell Line

    SciTech Connect

    Jinno-Oue, Atsushi; Shimizu, Nobuaki; Hamada, Nobuyuki; Wada, Seiichi; Tanaka, Atsushi; Shinagawa, Masahiko; Ohtsuki, Takahiro; Mori, Takahisa; Saha, Manujendra N.; Hoque, Ariful S.; Islam, Salequl; Kogure, Kimitaka; Funayama, Tomoo; Kobayashi, Yasuhiko

    2010-01-15

    Purpose: We examined biological responses of human glioma cells to irradiation with carbon ion beams (C-ions). Methods and Materials: A human glioma-derived cell line, NP-2, was irradiated with C-ions. Apoptotic cell nuclei were stained with Hoechst 33342. Induction of autophagy was examined either by staining cells with monodansylcadaverine (MDC) or by Western blotting to detect conversion of microtuble-associated protein light chain 3 (MAP-LC3) (LC3-I) to the membrane-bound form (LC3-II). Cellular senescence markers including induction of senescence-associated beta-galactosidase (SA-beta-gal) were examined. The mean telomere length of irradiated cells was determined by Southern blot hybridization. Expression of tumor suppressor p53 and cyclin/cyclin-dependent kinase inhibitor p21{sup WAF1/CIP1} in the irradiated cells was analyzed by Western blotting. Results: When NP-2 cells were irradiated with C-ions at 6 Gy, the major population of the cells died of apoptosis and autophagy. The residual fraction of attached cells (<1% of initially irradiated cells) could not form a colony: however, they showed a morphological phenotype consistent with cellular senescence, that is, enlarged and flattened appearance. The senescent nature of these attached cells was further indicated by staining for SA-beta-gal. The mean telomere length was not changed after irradiation with C-ions. Phosphorylation of p53 at serine 15 as well as the expression of p21{sup WAF1/CIP1} was induced in NP-2 cells after irradiation. Furthermore, we found that irradiation with C-ions induced cellular senescence in a human glioma cell line lacking functional p53. Conclusions: Irradiation with C-ions induced apoptosis, autophagy, and cellular senescence in human glioma cells.

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

    SciTech Connect

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

    2011-12-01

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

  19. Development of a compact single ion irradiation system

    NASA Astrophysics Data System (ADS)

    Iida, T.; Tanaka, T.; Sato, F.; Tanimura, Y.

    2000-12-01

    A compact single ion irradiation system has been developed to examine energetic particle effects on materials and devices. The system has been constructed by use of commercially available and inexpensive standard components and can be easily recomposed according to beam requirements for various irradiation experiments. The beam adjustment was automatically performed by help of a computer program based on a modified SIMPLEX method. The beam performances of the system, i.e., pulse width, the number of ions included in one pulse and beam size were examined by use of a microchannel plate, a Si-SSD, a CCD image sensor and a CR-39 track detector, respectively. A beam of a single ion, 1 nsec in pulse width and several /spl mu/m in diameter has been successfully produced by this system.

  20. Effects on focused ion beam irradiation on MOS transistors

    SciTech Connect

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

    1997-04-01

    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.

  1. The new Sandia light ion microbeam

    NASA Astrophysics Data System (ADS)

    Vizkelethy, G.; Doyle, B. L.; McDaniel, F. L.

    2012-02-01

    The Ion Beam Laboratory of Sandia National Laboratories (SNL) was recently relocated into a brand new building. The 6 MV High Voltage Engineering (HVE) tandem accelerator (hosting the heavy ion microbeam and several analytical beam lines) and the 350 kV HVE implanter with a nanobeam were moved to the new building. There were several new pieces of equipment acquired associated with the move, among them a new high brightness 3 MV Pelletron accelerator, a high resolution light ion microbeam, a nanoimplanter, and a transmission electron microscope (TEM) connected to the tandem accelerator. In this paper this new facility will be described, and initial results of the new microbeam will be presented.

  2. Dependence of Ion Energy on PTFE Surface Modification Effect by Nitrogen Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Nakayama, Akihiko; Iwao, Toru; Yumoto, Motoshige

    PTFE (Poly-tetra-fluoro-ethylene) has superior characteristic. But, it has low adhesion force. In order to improve adhesion force, we have studied on surface modification of PTFE by using discharge under high E/n (E:electric field, n:particle density) condition in nitrogen. From the results, it was deduced that ion energy around 40 eV is effective for polar groups introduction. In addition, treated surface unevenness did not increase compared with the untreated one. Then, we performed nitrogen ion irradiation by changing ion energy. From the results, it is shown that low ion energy is effective for polar groups introduction. It is also shown that high energy ion suppresses surface roughness. Thus, we measured surface energy and composition of samples irradiated by high and low energy ions. When ion with 30 eV was irradiated for 5 minute and following it ion with 1060 eV was irradiated for 10 second, many polar groups were introduced and surface unevenness was kept at the untreatment level. From the results by XPS (X-ray Photoelectron Spectroscopy) analysis and FT-IR (Fourier transform Infrared Spectroscopy) analysis by using the ATR (Attenuated Total Reflection) method, it was confirmed that polar groups of oxygen component and cross-linked structure via nitrogen or carbon was introduced at the surface.

  3. Fluence dependent oscillatory amorphization and recrystallization in ion irradiation

    NASA Astrophysics Data System (ADS)

    Banu, Nasrin; Satpati, B.; Dev, B. N.

    2017-09-01

    Ion-beam-induced amorphization and recrystallization are well-known phenomena. At a constant ion flux, there is a substrate temperature TR such that, for T < TR the irradiation produces amorphization, whereas for T > TR, it produces recrystallization. However, both the processes do not happen at a given substrate temperature. Here we present a novel phenomenon of ion fluence dependent oscillatory amorphization and recrystallization in silicon at room temperature in a Si(5 nm)/Ni(15 nm)/Si system. Before the deposition of Ni on Si, a buffer Si layer was deposited on the Si substrate. Ion irradiation was carried out with 1 MeV Si+ ions in the fluence range 1 × 1014-3 × 1017 ions/cm2. At a fluence of 5 × 1016 ions/cm2, Si is amorphous up to a depth of ∼1.4 μm. However, at a fluence of 1 × 1017 ions/cm2 two narrow bands of recrystallized (rc) Si are formed within the amorphized Si. At 2 × 1017 ions/cm2 these rc-Si bands become amorphous again. At 3 × 1017 ions/cm2 the broader rc band reappears. This oscillatory amorphization/recrystallization behaviour is Ni-mediated. Energy dispersive X-ray map of Ni shows Ni accumulation at the top of the rc-Si bands. The top of the broader rc band is actually the buffer-Si/substrate-Si interface. TRIM simulation shows the appearance of a Ni-displacement-induced vacancy peak at the position of the narrow rc-Si band. Accumulation of Ni in these regions is associated with the recrystallization process. The Ni layer, with incorporation of Si, also passes through amorphization and recrystallization. At the highest fluence η-NiSi nanocrystals are formed in the Ni layer.

  4. Blue light irradiation suppresses dendritic cells activation in vitro.

    PubMed

    Fischer, Michael R; Abel, Manuela; Lopez Kostka, Susanna; Rudolph, Berenice; Becker, Detlef; von Stebut, Esther

    2013-08-01

    Blue light is a UV-free irradiation suitable for treating chronic skin inflammation, for example, atopic dermatitis, psoriasis, and hand- and foot eczema. However, a better understanding of the mode of action is still missing. For this reason, we investigated whether dendritic cells (DC) are directly affected by blue light irradiation in vitro. Here, we report that irradiation neither induced apoptosis nor maturation of monocyte-derived and myeloid DC. However, subsequent DC maturation upon LPS/IFNγ stimulation was impaired in a dose-dependent manner as assessed by maturation markers and cytokine release. Moreover, the potential of this DC to induce cytokine secretion from allogeneic CD4 T cells was reduced. In conclusion, unlike UV irradiation, blue light irradiation at high and low doses only resulted in impaired DC maturation upon activation and a reduced subsequent stimulatory capacity in allogeneic MLRs with strongest effects at higher doses. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Visualization of air and metal inhomogeneities in phantoms irradiated by carbon ion beams using prompt secondary ions.

    PubMed

    Gaa, T; Reinhart, M; Hartmann, B; Jakubek, J; Soukup, P; Jäkel, O; Martišíková, M

    2017-06-01

    Non-invasive methods for monitoring of the therapeutic ion beam extension in the patient are desired in order to handle deteriorations of the dose distribution related to changes of the patient geometry. In carbon ion radiotherapy, secondary light ions represent one of potential sources of information about the dose distribution in the irradiated target. The capability to detect range-changing inhomogeneities inside of an otherwise homogeneous phantom, based on single track measurements, is addressed in this paper. Air and stainless steel inhomogeneities, with PMMA equivalent thickness of 10mm and 4.8mm respectively, were inserted into a PMMA-phantom at different positions in depth. Irradiations of the phantom with therapeutic carbon ion pencil beams were performed at the Heidelberg Ion Beam Therapy Center. Tracks of single secondary ions escaping the phantom under irradiation were detected with a pixelized semiconductor detector Timepix. The statistical relevance of the found differences between the track distributions with and without inhomogeneities was evaluated. Measured shifts of the distal edge and changes in the fragmentation probability make the presence of inhomogeneities inserted into the traversed medium detectable for both, 10mm air cavities and 1mm thick stainless steel. Moreover, the method was shown to be sensitive also on their position in the observed body, even when localized behind the Bragg-peak. The presented results demonstrate experimentally, that the method using distributions of single secondary ion tracks is sensitive to the changes of homogeneity of the traversed material for the studied geometries of the target. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  6. Late degeneration in rabbit tissues after irradiation by heavy ions

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  7. An infrared study of pure and ion irradiated frozen formamide

    NASA Astrophysics Data System (ADS)

    Brucato, J. R.; Baratta, G. A.; Strazzulla, G.

    2006-08-01

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

  8. Late degeneration in rabbit tissues after irradiation by heavy ions

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  9. Elastic wave from fast heavy ion irradiation on solids

    NASA Astrophysics Data System (ADS)

    Kambara, T.; Kageyama, K.; Kanai, Y.; Kojima, T. M.; Nanai, Y.; Yoneda, A.; Yamazaki, Y.

    2002-06-01

    To study the time-dependent mechanical effects of fast heavy ion irradiations, we have irradiated various solids by a short-bunch beam of 95 MeV/u Ar ions and observed elastic waves generated in the bulk. The irradiated targets were square-shaped plates of poly-crystals of metals (Al and Cu), invar alloy, ceramic (Al 2O 3), fused silica (SiO 2) and single crystals of KC1 and LiF with a thickness of 10 mm. The beam was incident perpendicular to the surface and all ions were stopped in the target. Two piezo-electric ultrasonic sensors were attached to the surface of the target and detected the elastic waves. The elastic waveforms as well as the time structure and intensity of the beam bunch were recorded for each shot of a beam bunch. The sensor placed opposite to the beam spot recorded a clear waveform of the longitudinal wave across the material, except for the invar and fused silica targets. From its propagation time along with the sound velocity and the thickness of the target, the depth of the wave source was estimated. The result was compared with ion ranges calculated for these materials by TRIM code.

  10. Magnetic properties of graphite irradiated with MeV ions

    SciTech Connect

    Ramos, M. A.; Munoz-Martin, A.; Climent-Font, A.; Barzola-Quiquia, J.; Esquinazi, P.; Garcia-Hernandez, M.

    2010-06-01

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

  11. Acclimation strategy of Rhodopseudomonas palustris to high light irradiance.

    PubMed

    Muzziotti, Dayana; Adessi, Alessandra; Faraloni, Cecilia; Torzillo, Giuseppe; De Philippis, Roberto

    2017-04-01

    The ability of Rhodopseudomonas palustris cells to rapidly acclimate to high light irradiance is an essential issue when cells are grown under sunlight. The aim of this study was to investigate the photo-acclimation process in Rhodopseudomonas palustris 42OL under different culturing conditions: (i) anaerobic (AnG), (ii) aerobic (AG), and (iii) under H2-producing (HP) conditions both at low (LL) and high light (HL) irradiances. The results obtained clearly showed that the photosynthetic unit was significantly affected by the light irradiance at which Rp. palustris 42OL was grown. The synthesis of carotenoids was affected by both illumination and culturing conditions. At LL, lycopene was the main carotenoid synthetized under all conditions tested, while at HL under HP conditions, it resulted the predominant carotenoid. Oppositely, under AnG and AG at HL, rhodovibrin was the major carotenoid detected. The increase in light intensity produced a deeper variation in light-harvesting complexes (LHC) ratio. These findings are important for understanding the ecological distribution of PNSB in natural environments, mostly characterized by high light intensities, and for its growth outdoors.

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    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.

  13. Formation of complex precursors of amino acids by irradiation of simulated interstellar media with heavy ions

    NASA Astrophysics Data System (ADS)

    Kobayashi, K.; Suzuki, N.; Taniuchi, T.; Kaneko, T.; Yoshida, S.

    A wide variety of organic compounds have been detected in such extraterrestrial bodies as meteorites and comets Amino acids were identified in the extracts from Murchison meteorite and other carbonaceous chondrites It is hypothesized that these compounds are originally formed in ice mantles of interstellar dusts ISDs in molecular clouds by cosmic rays and ultraviolet light UV Formation of amino acid precursors by high energy protons or UV irradiation of simulated ISDs was reported by several groups The amino acid precursors were however not well-characterized We irradiated a frozen mixture of methanol ammonia and water with heavy ions to study possible organic compounds abiotically formed in molecular clouds by cosmic rays A mixture of methanol ammonia and water was irradiated with carbon beams 290 MeV u from a heavy ion accelerator HIMAC of National Institute of Radiological Sciences Japan Irradiation was performed either at room temperature liquid phase or at 77 K solid phase The products were characterized by gel filtration chromatography GFC FT-IR pyrolysis PY -GC MS etc Amino acids were analyzed by HPLC and GC MS after acid hydrolysis or the products Amino acids such as glycine and alanine were identified in the products in both the cases of liquid phase and solid phase irradiation Energy yields G-values of glycine were 0 014 liquid phase and 0 007 solid phase respectively Average molecular weights of the products were estimated as to 2300 in both the case Aromatic hydrocarbons N-containing heterocyclic

  14. Ferromagnetic resonance study of ion irradiated Co/Ni multilayers with perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Beaujour, J.-M.; Kent, A.; Ravelosona, D.; Fullerton, E.; Samson, Y.; Beigne, C.

    2009-03-01

    Ferromagnetic resonance (FMR) spectroscopy was used to investigate the effect of helium ion-irradiation on the magnetic properties and the magnetization dynamics of Co/Ni multilayer films. The anisotropy in these materials is associated with interfaces, which can be systematically disordered with light ion-irradiation without inducing major structural changes to the films. [Pd/Co]x2|[8åNi/1.4åCo]x3 |Pd|Co|Pd| have been exposed to He^+ irradiation with fluence up to 10^15 ions/cm^2 [1]. FMR was conducted with a broad band coplanar waveguide up to 30 GHz. The resonance field and the FMR linewidth were determined as a function of frequency for dc magnetic fields in-plane, out-of-plane and for selected field angles. The perpendicular anisotropy decreases linearly with fluence, and at a particular fluence the direction of easy magnetization switches from perpendicular to in-plane. The Gilbert damping constant of the films irradiated at the higher and lower fluence is about the same: 0.03<=α<=0.04. However, the linewidth exhibits a non-monotonic dependence on fluence, with a maximum at intermediate fluence. We will discuss this effect as well as possible explanations in terms of the changes in interface structure as a function of fluence. [1] Stanescu et al., J. Appl. Phys. (2008).

  15. He ion irradiation damage in Al/Nb multilayers

    SciTech Connect

    Li Nan; Anderoglu, O.; Zhang, X.; Martin, M. S.; Shao, L.; Misra, A.; Wang, H.

    2009-06-15

    We investigate the evolution of microstructure and mechanical properties of sputter-deposited Al/Nb multilayers with miscible fcc/bcc type interface and individual layer thickness, h, of 1-200 nm, subjected to helium ion irradiations: 100 keV He{sup +} ions and a fluence of 6x10{sup 16}/cm{sup 2}. Helium bubbles, 1-2 nm in diameter, are 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 phase 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.

  16. Tunable nanometer electrode gaps by MeV ion irradiation

    SciTech Connect

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

    2012-04-09

    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.

  17. He ion irradiation damage to Al/Nb multilayers

    SciTech Connect

    Misra, Amit; Li, Nan; Martin, M S; Anderoglu, Osman; Shao, L; Wang, H; Zhang, X

    2009-01-01

    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.

  18. Mutagenic effects of heavy ion irradiation on rice seeds

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  19. Temperature measurements during high flux ion beam irradiations

    SciTech Connect

    Crespillo, Miguel L.; Graham, Joseph T.; Zhang, Yanwen; Weber, William J.

    2016-02-16

    A systematic study of the ion beam heating effect was performed in a temperature range of –170 to 900 °C using a 10 MeV Au3+ ion beam and a Yttria stabilized Zirconia (YSZ) sample at a flux of 5.5 × 1012 cm–2 s–1. Different geometric configurations of beam, sample, thermocouple positioning, and sample holder were compared to understand the heat/charge transport mechanisms responsible for the observed temperature increase. The beam heating exhibited a strong dependence on the background (initial) sample temperature with the largest temperature increases occurring at cryogenic temperatures and decreasing with increasing temperature. Comparison with numerical calculations suggests that the observed heating effect is, in reality, a predominantly electronic effect and the true temperature rise is small. Furthermore, a simple model was developed to explain this electronic effect in terms of an electrostatic potential that forms during ion irradiation. Such an artificial beam heating effect is potentially problematic in thermostated ion irradiation and ion beamanalysis apparatus, as the operation of temperature feedback systems can be significantly distorted by this effect.

  20. Temperature measurements during high flux ion beam irradiations

    DOE PAGES

    Crespillo, Miguel L.; Graham, Joseph T.; Zhang, Yanwen; ...

    2016-02-16

    A systematic study of the ion beam heating effect was performed in a temperature range of –170 to 900 °C using a 10 MeV Au3+ ion beam and a Yttria stabilized Zirconia (YSZ) sample at a flux of 5.5 × 1012 cm–2 s–1. Different geometric configurations of beam, sample, thermocouple positioning, and sample holder were compared to understand the heat/charge transport mechanisms responsible for the observed temperature increase. The beam heating exhibited a strong dependence on the background (initial) sample temperature with the largest temperature increases occurring at cryogenic temperatures and decreasing with increasing temperature. Comparison with numerical calculations suggestsmore » that the observed heating effect is, in reality, a predominantly electronic effect and the true temperature rise is small. Furthermore, a simple model was developed to explain this electronic effect in terms of an electrostatic potential that forms during ion irradiation. Such an artificial beam heating effect is potentially problematic in thermostated ion irradiation and ion beamanalysis apparatus, as the operation of temperature feedback systems can be significantly distorted by this effect.« less

  1. Track Structure in DNA Irradiated with Heavy Ions

    SciTech Connect

    Bowman, Michael K.; Becker, David; Sevilla, Michael D.; Zimbrick, John D.

    2005-04-01

    The spatial properties of trapped radicals produced in heavy ion-irradiated solid DNA at 77 K have been probed using pulsed Electron Paramagnetic Double Resonance (PELDOR or DEER) techniques. Salmon testes DNA hydrated to twelve water molecules per nucleotide was irradiated with 40Ar ions of energy 100 MeV/nucleon and LET ranging from 300 to 400 keV/?. Irradiated samples were maintained at cryogenic temperature at all times. PELDOR measurements were made using a refocused echo detection sequence that allows dipolar interaction between trapped radicals to be observed. The EPR spectrum is attributed to electron loss/gain DNA base radicals and neutral carbon-centered radicals that likely arise from sugar damage. We find a radical concentration of 13.5*1018 cm-3 in the tracks and a track radius of 6.79 nm. The cross section of these tracks is 144 nm2 yielding a lineal radical density of 2.6 radicals/nm. Based upon the yields previously determined for particles having calculated LET values of 300-400 keV/mm and our measured lineal density, we obtain an LET of 270 keV/mm, which is in good agreement with the calculated range of values. These measurements of radical density and spatial extent provide the first direct experimental determination of track characteristics in irradiated DNA.

  2. On Cherenkov light production by irradiated nuclear fuel rods

    NASA Astrophysics Data System (ADS)

    Branger, E.; Grape, S.; Jacobsson Svärd, S.; Jansson, P.; Andersson Sundén, E.

    2017-06-01

    Safeguards verification of irradiated nuclear fuel assemblies in wet storage is frequently done by measuring the Cherenkov light in the surrounding water produced due to radioactive decays of fission products in the fuel. This paper accounts for the physical processes behind the Cherenkov light production caused by a single fuel rod in wet storage, and simulations are presented that investigate to what extent various properties of the rod affect the Cherenkov light production. The results show that the fuel properties have a noticeable effect on the Cherenkov light production, and thus that the prediction models for Cherenkov light production which are used in the safeguards verifications could potentially be improved by considering these properties. It is concluded that the dominating source of the Cherenkov light is gamma-ray interactions with electrons in the surrounding water. Electrons created from beta decay may also exit the fuel and produce Cherenkov light, and e.g. Y-90 was identified as a possible contributor to significant levels of the measurable Cherenkov light in long-cooled fuel. The results also show that the cylindrical, elongated fuel rod geometry results in a non-isotropic Cherenkov light production, and the light component parallel to the rod's axis exhibits a dependence on gamma-ray energy that differs from the total intensity, which is of importance since the typical safeguards measurement situation observes the vertical light component. It is also concluded that the radial distributions of the radiation sources in a fuel rod will affect the Cherenkov light production.

  3. Protective coatings preventing hydrogen desorption from titanium during ion irradiation

    NASA Astrophysics Data System (ADS)

    Evsin, A. E.; Begrambekov, L. B.; Dovganyuk, S. S.; Kaplevsky, A. S.; Shutikova, M. I.

    2017-05-01

    Effect of yttria and titanium nitride coatings on features of deuterium desorption from titanium layer is investigated. It is shown that both coatings significantly raise the temperature of maximum of deuterium thermal desorption from titanium under linear heating and prevent desorption under prolonged keeping at the operating temperature of a neutron tube target. However, under irradiation with ions of H2 + O2 plasma the barrier properties of titanium nitride appear to degrade.

  4. A Raman study of ion irradiated icy mixtures

    NASA Astrophysics Data System (ADS)

    Ferini, G.; Baratta, G. A.; Palumbo, M. E.

    2004-02-01

    In this paper we present a Raman study of pure CH4, H2O:CH4:N2 and CH3OH:N2 frozen films before and after ion irradiation at 12 K, 100 K and 300 K. By means of Raman spectroscopy, we monitor the structural evolution of each film, whose chemical and physical properties are deeply modified by the interaction with the ion beam. For the two methane containing samples, Raman spectra show that the initial ice is partially converted into a refractory residue, which under further irradiation evolves towards an amorphous carbon (AC) with a band near 1560 cm-1 (G line) and a shoulder at about 1360 cm-1 (D line). No evidence of the AC Raman band is seen in the spectra of the methanol-containing mixture. By means of Lorentzian fits, we have determined the specific parameters of the AC band (G and D line peak positions, widths and relative intensities) in our spectra after ion irradiation and we have compared them with the corresponding parameters of the band as observed in the spectra of 11 IDPs (Interplanetary Dust Particles). Here we present the experimental results and discuss their contribution to our knowledge of the origin and evolution of IDPs.

  5. A Raman study of ion irradiated icy mixtures

    NASA Astrophysics Data System (ADS)

    Baratta, G. A.; Ferini, G.; Palumbo, M. E.

    2003-04-01

    We present a Raman study of pure CH_4, H_2O:CH_4:N_2 and CH_3OH:N_2 frozen films before and after ion irradiation at low (12 K) and high (100 K or 300 K) temperature. By means of Raman spectroscopy, we monitor the structural evolution of each film, whose optical properties are deeply modified by the interaction with the ion beam. Raman spectra show that the sample is partially converted into a refractory residue, which under further irradiation evolves towards an amorphous carbon with a band near 1560 cm-1 (G line) and a shoulder at about 1360 cm-1 (D line). The specific parameters of this 'double-peaked' feature (peaks position, widths and relative intensities) can be used as diagnostic to classify different carbonaceous materials and infer information about their degree of order. We have compared these parameters for our samples (ion irradiated frozen films and residues), for different kinds of hydrogenated carbon grains and for some IDPs. We have found that IDPs have in general a narrower G line, which peaks at higher wavenumbers, than most of the laboratory samples here discussed. This implies that IDPs have a structure with a higher degree of order than that of our samples. Here we present the experimenal results and discuss their relevance to the study of the origin and evolution of IDPs.

  6. Manipulation of the graphene surface potential by ion irradiation

    SciTech Connect

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

    2013-04-15

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

  7. Ion irradiation of AZO thin films for flexible electronics

    NASA Astrophysics Data System (ADS)

    Boscarino, Stefano; Torrisi, Giacomo; Crupi, Isodiana; Alberti, Alessandra; Mirabella, Salvatore; Ruffino, Francesco; Terrasi, Antonio

    2017-02-01

    Aluminum doped Zinc oxide (AZO) is a promising transparent conductor for solar cells, displays and touch-screen technologies. The resistivity of AZO is typically improved by thermal annealing at temperatures not suitable for plastic substrates. Here we present a non-thermal route to improve the electrical and structural properties of AZO by irradiating the TCO films with O+ or Ar+ ion beams (30-350 keV, 3 × 1015-3 × 1016 ions/cm2) after the deposition on glass and flexible polyethylene naphthalate (PEN). X-ray diffraction, optical absorption, electrical measurements, Rutherford Backscattering Spectrometry and Atomic Force Microscopy evidenced an increase of the crystalline grain size and a complete relief of the lattice strain upon ion beam irradiation. Indeed, the resistivity of thin AZO films irradiated at room temperature decreased of two orders of magnitude, similarly to a thermal annealing at 400 °C. We also show that the improvement of the electrical properties does not simply depend on the strain or polycrystalline domain size, as often stated in the literature.

  8. Angular distributions of sputtered atoms for low-energy heavy ions, medium ions and light ions

    NASA Astrophysics Data System (ADS)

    Yamamura, Yasunori; Mizuno, Yoshiyuki; Kimura, Hidetoshi

    1986-03-01

    The angular distributions of sputtered atoms for the near-threshold sputtering of heavy ions, medium ions, and light ions have been investigated by a few-collision model and the ACAT computer simulation code. For heavy-ion sputtering the preferential angle of sputtered atoms is about 50° which is measured from the surface normal, while in the case of the near-threshold light-ion sputtering the preferential angles are nearly equal to the surface normal and do not depend on angle of incidence. It is found that the agreement between the ACAT preferential angles and theoretical values due to a few-collision model is very good.

  9. Swift heavy ion-irradiation effects on microstructure, surface morphology and optical properties of PbS thin films

    NASA Astrophysics Data System (ADS)

    Rajbongshi, Ananta; Kalita, M. P. C.; Singh, F.; Sarma, K. C.; Sarma, B. K.

    2016-05-01

    Chemically deposited PbS nanocrystalline thin films are irradiated by 100 MeV Si8+ swift heavy ions of fluences 1 × 1011, 1 × 1012 and 1 × 1013 ions/cm2. Detailed investigation on the effects of irradiation on microstructure is carried out by X-ray diffraction line profile analysis applying Williamson-Hall and modified Williamson-Hall methods, and transmission electron microscope observation, while atomic force microscope is used for studying the modifications in surface morphology. The band gaps are obtained from electronic absorption spectroscopy measurements, and photoluminescence spectra are recorded by spectrofluorometer. The pristine and irradiated films are polycrystalline in nature with spherical crystallites having face-centered cubic phase. The crystallite size of the pristine film is 20 nm, while films irradiated with ion fluences 1 × 1011, 1 × 1012 and 1 × 1013 ions/cm2 are 21, 20 and 20 nm, respectively. The lattice strain (dislocation density) of the pristine film is 8.9 × 10-3 (6.6 × 1016 m-2), while films irradiated with ion fluences 1 × 1011, 1 × 1012 and 1 × 1013 ions/cm2 are 8.6 × 10-3 (6.1 × 1016 m-2), 8.7 × 10-3 (6.4 × 1016 m-2) and 9.1 × 10-3 (7.0 × 1016 m-2), respectively. The dislocations present in both the pristine and irradiated films are edge in nature. The surface morphology changes significantly with elongation of the particles, increase in particle size and interparticle separation and slight decrease in rms roughness after irradiation. The band gap of the pristine film is 2.51 eV which remains unaltered after irradiation. Photoluminescence intensity increases significantly after irradiation which can be useful in enhancing the performance of different photonic devices such as light-emitting diodes, lasers and luminescence-based sensors.

  10. Ion exchange in KTiOPO4 crystals irradiated by copper and hydrogen ions.

    PubMed

    Zhang, Ruifeng; Lu, Fei; Lian, Jie; Liu, Hanping; Liu, Xiangzhi; Lu, Qingming; Ma, Hongji

    2008-05-12

    Cs(+)-K+ ion exchanges were produced on KTiOPO4 crystals which is prior irradiated by Cu+ can H+ ions. The energy and dose of implanted Cu+ ions are 1.5 MeV and 0.5 x 10(14) ions/cm2, and that of H+ are 300 keV and 1 x 10(16) ions/cm2, respectively. The temperature of ions exchange is 430 degrees C, and the time range from 15 minutes to 30 minutes. The prism coupling method is used to measure the dark mode spectra of the samples. Compared with results of ion exchange on the sample without irradiations, both the number of guided mode and its corresponding effective refractive index are decreased. The experimental results indicate that the ion exchange rate closely related with the lattice damage and the damage layers formed in the depth of maximum nuclear energy deposition act as a barrier to block the ions diffuse into the sample and the concentration of defects can modify the speed of ion exchange..

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

    NASA Astrophysics Data System (ADS)

    Ferain, E.; Legras, R.

    1993-09-01

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

  12. Semiconducting Properties of Swift Au Ion-Irradiated ZnO Thin Films at Room Temperature

    NASA Astrophysics Data System (ADS)

    Kwon, Sera; Park, Hyun-Woo; Chung, Kwun-Bum

    2017-02-01

    The semiconducting properties of Au ion-irradiated ZnO thin films were investigated as a function of ion irradiation dose at room temperature. The Au ion irradiation was conducted with acceleration energy of 130 MeV in the ion dose range from 1 × 1011 to 5 × 1012 ions/cm2. The physical properties showed no change regardless of the Au ion irradiation dose; however, the electrical properties of Au ion-irradiated ZnO thin films changed, depending on the Au ion irradiation dose. The electronic structure drastically changed with the evolution of hybridized molecular orbital structure for the conduction band and band edge states below the conduction band. These remarkable changes in electronic structure correlate with changes in electrical properties, such as carrier concentration and mobility.

  13. Characterization of polymeric films subjected to lithium ion beam irradiation

    NASA Astrophysics Data System (ADS)

    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

    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 Hrad and OHrad . 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

  14. Characterization of polymeric films subjected to lithium ion beam irradiation

    SciTech Connect

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

    2013-02-01

    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 Hradical dot and OHradical dot. 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

  15. Ion irradiation damage in ilmenite under cryogenic conditions

    SciTech Connect

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

    1996-11-01

    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.

  16. Ion irradiation damage in ilmenite at 100 K

    USGS Publications Warehouse

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

    1997-01-01

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

  17. Dislocation loop formation by swift heavy ion irradiation of metals

    NASA Astrophysics Data System (ADS)

    Khara, Galvin S.; Murphy, Samuel T.; Duffy, Dorothy M.

    2017-07-01

    A coupled two-temperature, molecular dynamics methodology is used to simulate the structural evolution of bcc metals (Fe and W) and fcc metals (Cu and Ni) following irradiation by swift heavy ions. Electronic temperature dependent electronic specific heat capacities and electron-phonon coupling strengths are used to capture the full effects of the variation in the electronic density of states. Tungsten is found to be significantly more resistant to damage than iron, due both to the higher melting temperature and the higher thermal conductivity. Very interesting defect structures, quite different from defects formed in cascades, are found to be created by swift heavy ion irradiation in the bcc metals. Isolated vacancies form a halo around elongated interstitial dislocation loops that are oriented along the ion path. Such configurations are formed by rapid recrystallization of the molten cylindrical region that is created by the energetic ion. Vacancies are created at the recrystallization front, resulting in excess atoms at the core which form interstitial dislocation loops on completion of crystallization. These unique defect structures could, potentially, be used to create metal films with superior mechanical properties and interesting nanostructures.

  18. Ion irradiation damage in ilmenite at 100 K

    SciTech Connect

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

    1997-10-01

    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.

  19. Control of light backscattering in blood during intravenous laser irradiation

    NASA Astrophysics Data System (ADS)

    Melnik, Ivan S.; Popov, V. D.; Rusina, Tatyana V.; Dets, Sergiy M.

    1997-02-01

    One of the most important problems in modern laser medicine is the determination of system response on laser treatment. Reaction of living system is significant during many kinds of laser procedures like surgery, therapy and biostimulation. Our study was aimed to optimize laser exposure using feed-back fiber system for intravenous laser irradiation of blood (ILIB). This system consisted of helium-neon laser (633 nm, 5 mW) with coupled fiber unit, photodetector and PC interface. Photodetector signals produced due to light backscattering were storaged and processed during all blood irradiation procedure. Significant time-dependent variations were observed within 9-15 min after beginning of treatment procedure and were correlated with number of trials, stage and character of disease. The designed feed-back system allows us to register a human blood response on laser irradiation to achieve better cure effect.

  20. Progress toward fusion with light ions

    SciTech Connect

    1980-01-01

    New results in target design, beam generation and transport, and pulse power technology have led to a program shift stressing light ion-driven inertial confinement fusion. According to present estimates, a gain ten fusion pellet will require at least one megajoule and approx. 100 TW power input. Progress in ion sources has resulted in beam power density of approx. 1 TW/cm/sup 2/, a factor of ten increase over the last year, and cylindrical implosion experiments have been performed. Other experiments have demonstrated the ability to transport ion and electron beams with high efficiency and have confirmed numerical predictions on the properties of beam transport channels converging at a target. These developments together with improvements in pulse power technology allow us to project that the 72 beam, 100 TW Particle Beam Fusion Accelerator, PBFA-II will attain target output energy equal to stored energy in the accelerator.

  1. Study of ion-irradiated tungsten in deuterium plasma

    NASA Astrophysics Data System (ADS)

    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

    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/сm2. Erosion dynamics of the damaged layer and deuterium retention were observed. Surface microstructure modifications and important damage of the 5 μm 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.

  2. Reflection properties of hydrogen ions at helium irradiated tungsten surfaces

    NASA Astrophysics Data System (ADS)

    Doi, K.; Tawada, Y.; Lee, H. T.; Kato, S.; Tanaka, N.; Sasao, M.; Kisaki, M.; Nishiura, M.; Matsumoto, Y.; Kenmotsu, T.; Wada, M.; Ueda, Y.; Yamaoka, H.

    2016-02-01

    Nanostructured W surfaces prepared by He bombardment exhibit characteristic angular distributions of hydrogen ion reflection upon injection of 1 keV H+ beam. A magnetic momentum analyzer that can move in the vacuum chamber has measured the angular dependence of the intensity and the energy of reflected ions. Broader angular distributions were observed for He-irradiated tungsten samples compared with that of the intrinsic polycrystalline W. Both intensity and energy of reflected ions decreased in the following order: the polycrystalline W, the He-bubble containing W, and the fuzz W. Classical trajectory Monte Carlo simulations based on Atomic Collision in Amorphous Target code suggests that lower atom density near the surface can make the reflection coefficients lower due to increasing number of collisions.

  3. Investigations of Atomic Transport Induced by Heavy Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Banwell, Thomas Clyde

    The mechanisms of atomic transport induced by ion irradiation generally fall into the categories of anisotropic or isotropic processes. Typical examples of these are recoil implantation and cascade mixing, respectively. We have measured the interaction of these processes in the mixing of Ti/SiO(,2)/Si, Cr/SiO(,2)/Si and Ni/SiO(,2)/Si multi-layers irradiated with Xe at fluences of 0.01 - 10 x 10('15)cm('-2). The fluence dependence of net metal transport into the underlying layers was measured with different thicknesses of SiO(,2) and different sample temperatures during irradiation (-196 to 500C). There is a linear dependence at low fluences. At high fluences, a square-root behavior predominates. For thin SiO(,2) layers (<20nm), the cross -over point depends on the SiO(,2) thickness. These results are readily interpreted in terms of competition between the flux of injected atoms and diffusion of the accumulating metal. The detailed analysis allows us to speculate on the role of chemical reaction kinetics in controlling the outcome of intra-cascade processes. There is no significant correlation between the reactivity of the metal with SiO(,2) and the amount of mixing observed when the irradiations are performed at 25C or below. The contribution from primary recoils is quite pronounced since the gross mixing is small. A significant correlation exists between the mixing and the energy deposited through elastic collisions F(,D ). Several models are examined in an attempt to describe the transport process in Ni/SiO(,2). It is likely that injection of Ni by secondary recoil implantation is primarily responsible for getting Ni into the SiO(,2). Secondary recoil injection is thought to scale with F(,D). Trends in the mixing rates indicate that the dominant mechanism for Ti and Cr could be the same as for Ni. The processes of atomic transport and phase formation clearly fail to be separable at higher temperatures. A positive correlation with chemical reactivity emerges at

  4. Disk irradiation and light curves of x ray novae

    NASA Technical Reports Server (NTRS)

    Kim, S.-W.; Wheeler, J. C.; Mineshige, S.

    1994-01-01

    We study the disk instability and the effect of irradiation on outbursts in the black hole X-ray nova system. In both the optical and soft X-rays, the light curves of several X-ray novae, A0620-00, GH 2000+25, Nova Muscae 1991 (GS 1124-68), and GRO J0422+32, show a main peak, a phase of exponential decline, a secondary maximum or reflare, and a final bump in the late decay followed by a rapid decline. Basic disk thermal limit cycle instabilities can account for the rapid rise and overall decline, but not the reflare and final bump. The rise time of the reflare, about 10 days, is too short to represent a viscous time, so this event is unlikely to be due to increased mass flow from the companion star. We explore the possibility that irradiation by X-rays produced in the inner disk can produce these secondary effects by enhancing the mass flow rate within the disk. Two plausible mechanisms of irradiation of the disk are considered: direct irradiation from the inner hot disk and reflected radiation from a corona or other structure above the disk. Both of these processes will be time dependent in the context of the disk instability model and result in more complex time-dependent behavior of the disk structure. We test both disk instability and mass transfer burst models for the secondary flares in the presence of irradiation.

  5. Swift heavy ion irradiation reduces porous silicon thermal conductivity

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. Point defects reactions in ion irradiated SiC

    NASA Astrophysics Data System (ADS)

    Litrico, G.; Zimbone, M.; Baratta, G.; Marino, A. D. M.; Musumeci, P.; Calcagno, L.

    2010-10-01

    The defects produced in 4H-SiC epitaxial layers by irradiation with 800 keV C + were characterized by Low Temperature Photoluminescence. Ion beam irradiation induces the formation of some sharp lines in the wavelength range 428-441 nm of the photoluminescence spectra, that are typically known as "alphabet lines". These photoluminescence features are due to the recombination of excitons at structural defects. The photoluminescence results allow to single out two groups of peaks: the P 1 lines ( e-f-g) and the P 2 lines ( a-b-c-d), that exhibit a different trend with the ion fluence. The P 1 group intensity increases with fluence and tends to reach a saturation value at high fluence. The P 2 group yield, instead, exhibits a threshold at low fluence and then increases toward a saturation. Subsequent UV-laser irradiation decreases the intensity of the P 2 lines related to a change in the structural configuration of the associated defects.

  7. Microstructure of RERTR DU-Alloys Irradiated with Krypton Ions

    SciTech Connect

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

    2009-11-01

    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.

  8. Amorphization of SiC under ion and neutron irradiation

    NASA Astrophysics Data System (ADS)

    Snead, L. L.; Zinkle, S. J.; Hay, J. C.; Osborne, M. C.

    1998-05-01

    This paper presents results on the microstructure and physical properties of SiC amorphized by both ion and neutron irradiation. Specifically, 0.56 MeV Si ions have been implanted in single crystal 6H-SiC from ambient through >200°C and the critical threshold for amorphization was measured as a function of the irradiation temperature. From a high resolution transmission electron microscopy (HRTEM) study of the crystalline to amorphous transition region in these materials, elongated pockets of amorphous material oriented parallel to the free surface are observed. Single crystal 6H-SiC and hot pressed and sintered 6H and 3C SiC were neutron irradiated at approximately 70°C to a dose of ˜2.56 dpa causing complete amorphization. Property changes resulting from the crystal to amorphous transition in SiC include a density decrease of 10.8%, a hardness decrease from 38.7 to 21.0 GPa, and a decrease in elastic modulus from 528 to 292 GPa. Recrystallization of the amorphized, single crystal 6H-SiC appears to occur in two stages. In the temperature range of ˜800-1000°C, crystallites nucleate and slowly grow. In the temperature range of 1125-1150°C spontaneous nucleation and rapid growth of crystallites occur. It is further noted that amorphized 6H (alpha) SiC recrystallizes to highly faulted fcc (beta) SiC.

  9. Effect of polarized light emitting diode irradiation on wound healing.

    PubMed

    Tada, Kaoru; Ikeda, Kazuo; Tomita, Katsuro

    2009-11-01

    We propose a new phototherapy using polarized light from light emitting diode (LED). The purpose of this study is to clarify the effect of polarized LED irradiation on wound healing. Five groups were classified: control (C), unpolarized (U), linearly polarized (L), right circularly polarized (RC), and left circularly polarized (LC) LED irradiation. In vitro study, fibroblast cell cultures were irradiated, and cellular proliferation was evaluated with a WST-8 assay. In vivo study, full-thickness skin defect of 20 mm diameter was created on the dorsal side of rats. The ratio of the residual wound area was measured, and expression of type 1 and type 3 procollagen mRNA in granulation tissue was determined by real-time reverse transcription polymerase chain reaction method. The cellular proliferation rates of group RC and L were significantly higher than other groups. The ratio of the residual wound area of group RC and L was significantly reduced than group C and U. Expression of type 1 procollagen mRNA in group RC was found to be significantly increased about 1.5-fold in comparison with the group C. There were no significant differences for type 3 procollagen. The right circularly polarized light and linearly polarized light promoted the process of wound healing by increasing the proliferation of fibroblasts, and the right circularly polarized light increased the expression of type 1 procollagen mRNA. The effectiveness of right circularly polarized light suggests that some optical active material, which has a circular dichroic spectrum, takes part in a biochemical reaction.

  10. A mechanism of cell apoptosis by light irradiation

    NASA Astrophysics Data System (ADS)

    Xing, Da; Gao, Xuejuan; Wang, Fang

    2006-02-01

    Light irradiation can modulate various biological processes. For instance, low-power laser irradiation (LPLI) can induce cell proliferation and differentiation. It has been used to treat diseases of regeneration limitation and to promote wound healing. The biological mechanism of light irradiation remains unclear. Our previous studies have shown that low fluence LPLI induced the proliferation of human lung adenocarcinoma cells (ASTC-a-1) through PKC channel, while high fluence LPLI induced caspase-3 activation and cell apoptosis. The mechanisms of the initiation and regulation of apoptosis are complex and diverse. There are two main pathways to initiate and regulate cell apoptosis, one is the death receptor pathway (receptor/caspase-8/caspase-3), and the other is the mitochondria pathway (mitochondria/ caspase-9/caspase-3). Using fluorescent imaging techniques, we observed a temporal sequence of events during apoptosis induced by high fluence LPLI and PDT. Both the high fluence LPLI and PDT triggers mitochondrial ROS production resulting in dissipation of ΔΨ m and activation of caspase-3. Our results also show the two treatments do not activate caspase-8. These results suggest that caspase-3 activation induced by high fluence LPLI or PDT is initiated directly from mitochondria ROS generation and dissipation of ΔΨ m, and independent of the cell death pathway involving caspase-8 activation. Because the progression of the apoptosis induced by high fluence LPLI is the same as that of PDT, we concluded that light is absorbed directly either by endogenous porphyrins or by the cytochromes in mitochondrion, resulting in initial ROS generation. During light irradiation induced apoptosis, apoptotic signals are initiated from mitochondrial ROS production due to photosensitization.

  11. The LILIA (laser induced light ions acceleration) experiment at LNF

    NASA Astrophysics Data System (ADS)

    Agosteo, S.; Anania, M. P.; Caresana, M.; Cirrone, G. A. P.; De Martinis, C.; Delle Side, D.; Fazzi, A.; Gatti, G.; Giove, D.; Giulietti, D.; Gizzi, L. A.; Labate, L.; Londrillo, P.; Maggiore, M.; Nassisi, V.; Sinigardi, S.; Tramontana, A.; Schillaci, F.; Scuderi, V.; Turchetti, G.; Varoli, V.; Velardi, L.

    2014-07-01

    Laser-matter interaction at relativistic intensities opens up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. LILIA (laser induced light ions acceleration) is an experiment now running at LNF (Frascati) with the goal of producing a real proton beam able to be driven for significant distances (50-75 cm) away from the interaction point and which will act as a source for further accelerating structure. In this paper the description of the experimental setup, the preliminary results of solid target irradiation and start to end simulation for a post-accelerated beam up to 60 MeV are given.

  12. Effects of heavy-ion irradiation on FeSe

    NASA Astrophysics Data System (ADS)

    Sun, Yue; Park, Akiyoshi; Pyon, Sunseng; Tamegai, Tsuyoshi; Kambara, Tadashi; Ichinose, Ataru

    2017-03-01

    We report the effects of heavy-ion irradiation on FeSe single crystals by irradiating uranium up to a dose-equivalent matching field of Bϕ=16 T. Almost continuous columnar defects along the c axis with a diameter of ˜10 nm are confirmed by high-resolution transmission electron microscopy. Tc is found to be suppressed by introducing columnar defects at a rate of d Tc/d Bϕ˜-0.29 K/T, which is much larger than those observed in iron pnictides. This unexpected large suppression of Tc in FeSe is discussed in relation to the large diameter of the columnar defects as well as its unique band structure with a remarkably small Fermi energy. The critical current density is first dramatically enhanced with irradiation reaching a value over ˜2 ×105A /cm2 (˜5 times larger than that of the pristine sample) at 2 K (self-field) with Bϕ=2 T, then gradually suppressed with increasing Bϕ. The δ l pinning associated with charge-carrier mean-free-path fluctuations and the δ Tc pinning associated with spatial fluctuations of the transition temperature are found to coexist in the pristine FeSe, while the irradiation increases the contribution from δ l pinning and makes it dominant over Bϕ=4 T.

  13. Influence of ion irradiation on iron-chalcogenide superconducting films

    NASA Astrophysics Data System (ADS)

    Ozaki, Toshinori; Si, Weidong; Zhang, Cheng; Wu, Lijun; Li, Qiang

    2015-03-01

    Iron-chalcogenide superconductors have rather simple crystal structure and no charge reservoir. They also exhibit remarkable properties including small anisotoropy, high upper critical fields, a significant pressure effect on superconductivity. We have grown iron-chalcogenide FeSe0.5Te0.5 (FST) superconducting films on various substrate by pulsed laser deposition. The FST films on CeO2 buffer layer exhibit enhanced Tc (Tconset >20 K, Tczero = 18.0 K), which is about 30% higher than that found in the bulk materials and superior high field performance over the low temperature superconductors.. Recently, we were successful in further enhancement of Jc without Tc degradation by ion irradiation, especially, at high temperature and high magnetic field. The low-energy proton irradiation produces a Jc enhancement of one order of magnitude over the field of 6T//c at 12 K. Extensive TEM studies of the irradiated FST films have been carried out, which revealed an intriguing defect morphology provided by the irradiation. We will discuss the relationship between the superconducting properties and the created defects of the iron-chalcogenide films.

  14. Chlorine diffusion in uranium dioxide under heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Pipon, Y.; Bérerd, N.; Moncoffre, N.; Peaucelle, C.; Toulhoat, N.; Jaffrézic, H.; Raimbault, L.; Sainsot, P.; Carlot, G.

    2007-04-01

    The radiation enhanced diffusion of chlorine in UO2 during heavy ion irradiation is studied. In order to simulate the behaviour of 36Cl, present as an impurity in UO2, 37Cl has been implanted into the samples (projected range 200 nm). The samples were then irradiated with 63.5 MeV 127I at two fluxes and two temperatures and the chlorine distribution was analyzed by SIMS. The results show that, during irradiation, the diffusion of the implanted chlorine is enhanced and slightly athermal with respect to pure thermal diffusion. A chlorine gain of 10% accumulating near the surface has been observed at 510 K. This corresponds to the displacement of pristine chlorine from a region of maximum defect concentration. This behaviour and the mean value of the apparent diffusion coefficient found for the implanted chlorine, around 2.5 × 10-14 cm2 s-1, reflect the high mobility of chlorine in UO2 during irradiation with fission products.

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

    SciTech Connect

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

    2014-09-24

    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.

  16. Raman spectroscopy of ion-irradiated interplanetary carbon dust analogues

    NASA Astrophysics Data System (ADS)

    Baratta, G. A.; Mennella, V.; Brucato, J. R.; Colangeli, L.; Leto, G.; Palumbo, M. E.; Strazzulla, G.

    Interplanetary dust particles (IDPs) and meteorites provide an unique opportunity to study extraterrestrial materials in laboratory. Different Raman studies have shown that most of IDPs exhibit the characteristic amorphous carbon Raman feature. Different degrees of order have been recognised in the amorphous carbon phase of IDPs testifying either to different origin or to different processing under different physical conditions (temperature, pressure etc.). This paper presents a comparison between the amorphous carbon Raman features of IDPs, and those of carbon dust analogues obtained in the laboratory by ion irradiation of carbon containing frozen gases and by arc discharge. We propose a possible mechanism able to induce an "evolution" of IDPs. In particular amorphous carbon with different degrees of order could be indicative of different irradiation doses by solar wind particles and fast solar protons, suffered by IDPs in the interplanetary medium before collection in the Earth's atmosphere.

  17. Impact of light irradiation on black tea quality during withering.

    PubMed

    Ai, Zeyi; Zhang, Beibei; Chen, Yuqiong; Yu, Zhi; Chen, Huacai; Ni, Dejiang

    2017-04-01

    Black tea manufacture usually involves the processes of withering, cutting, fermentation and drying. The aim of present study was to evaluate the effect of the relationship between the quality and withering with different light sources (ultraviolet, yellow, blue, purple, orange, red, cyan, green and white) an quality attribute of tea. The results indicated that the yellow, orange and red light withering significantly improved the aroma and taste, imparting the tea a sweet flavor and a fresh and mellow taste. Tea treated with yellow light was scored highest the sensory scores and showed the highest content in catechins, theaflavins, amino acids and aroma components, followed by the orange and red light treatments. The black tea withered with ultraviolet light showed a strong astringency, probably resulting from low contents of theaflavins, amino acids and soluble sugar. The green light irradiation remarkably damaged the aroma and taste of the tea, leading to a strong greenish flavor and an astringent taste, probably owing to the lowest contents of chemical compositions. No significant cumulative effect was found in the hybrid light withering treatments. Therefore, monochromatic yellow, orange and red lights were suggested for withering the black tea to improve its overall quality.

  18. Amorphization of diamond by ion irradiation: a Raman study

    NASA Astrophysics Data System (ADS)

    Brunetto, Rosario; Baratta, Giuseppe A.; Strazzulla, Giovanni

    2005-01-01

    We performed ion irradiation experiments on diamond samples at room temperature, probed by in-situ Raman spectroscopy. Different ions are used with energies of 200 or 400 keV. The intensity of diamond Raman band (at 1332 cm-1) decreases exponentially as the ion fluence increases. Results from different ions demonstrate that this effect is due to changes in the optical properties of the damaged samples and is correlated with the energy lost by ions through elastic collisions with target nuclei. Amorphous carbon (sp2) is formed after a threshold of about 2×1022 vacancies/cm3, or about 16 eV/C-atom deposited by elastic collisions. The peak position and full width at half maximum of the D-line and G-line of the synthesized amorphous carbon are studied. A comparison is made between the amorphization of diamond and that of graphite, forsterite, and water ice crystals. A linear relationship is found between the amorphization dose and the displacement energy. The results are discussed in view of their relevance in astrophysics.

  19. Defect recovery and damage reduction in borosilicate glasses under double ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Mir, A. H.; Peuget, S.; Toulemonde, M.; Bulot, P.; Jegou, C.; Miro, S.; Bouffard, S.

    2015-11-01

    A sodium borosilicate glass was irradiated sequentially and simultaneously with alpha particles and gold ions. Alpha particles induced partial recovery of the network damage and mechanical properties in the gold pre-irradiated glass, while no such recovery effect was observed during gold irradiation of the alpha pre-irradiated glass. The damage capacity of the gold ions was significantly reduced during simultaneous irradiation with alpha particles and gold ions. These results highlight that the irradiation sequence of the ions plays an important role in controlling the final damage level; and if properly employed, irradiation can be employed to induce defect recovery. Such results are of paramount importance to understand the radiation damage in nuclear reactor components and in nuclear waste glass matrices which are subjected to multiple particle irradiations.

  20. Systematic Ion Irradiation Experiments to Olivine: Comparison with Space Weathered Rims of Itokawa Regolith Particles

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Tsuchiyama, A.; Watanabe, N.; Yasuda, K.; Miyake, A.; Nakauchi, Y.; Okada, T.; Abe, M.; Yada, T.; Uesugi, M.; Karouji, Y.; Nakato, A.; Hashiguschi, M.; Kumagai, K.

    2015-11-01

    We performed H and He ion irradiation experiments using olivine fragments, in order to reveal formation time-scales of space weathered rims and formation processes of blisters by solar wind irradiation.

  1. Radiation damage by light- and heavy-ion bombardment of single-crystal LiNbO₃

    SciTech Connect

    Huang, Hsu-Cheng; Zhang, Lihua; Malladi, Girish; Dadap, Jerry I.; Manandhar, Sandeep; Kisslinger, Kim; Vemuri, Rama Sesha R.; Shutthanandan, Vaithiyalingam; Bakhru, Hassaram; Osgood, Jr., Richard M.

    2015-04-14

    In this work, a battery of analytical methods including in situ RBS/C, confocal micro-Raman, TEM/STEM, EDS, AFM, and optical microscopy were used to provide a comparative investigation of light- and heavy-ion radiation damage in single-crystal LiNbO₃. High (~MeV) and low (~100s keV) ion energies, corresponding to different stopping power mechanisms, were used and their associated damage events were observed. In addition, sequential irradiation of both ion species was also performed and their cumulative depth-dependent damage was determined. It was found that the contribution from electronic stopping by high-energy heavy ions gave rise to a lower critical fluence for damage formation than for the case of low-energy irradiation. Such energy-dependent critical fluence of heavy-ion irradiation is two to three orders of magnitude smaller than that for the case of light-ion damage. In addition, materials amorphization and collision cascades were seen for heavy-ion irradiation, while for light ion, crystallinity remained at the highest fluence used in the experiment. The irradiation-induced damage is characterized by the formation of defect clusters, elastic strain, surface deformation, as well as change in elemental composition. In particular, the presence of nanometric-scale damage pockets results in increased RBS/C backscattered signal and the appearance of normally forbidden Raman phonon modes. The location of the highest density of damage is in good agreement with SRIM calculations. (author)

  2. Photocatalytic activities of various pentavalent bismuthates under visible light irradiation

    SciTech Connect

    Takei, Takahiro; Haramoto, Rie; Dong, Qiang; Kumada, Nobuhiro; Yonesaki, Yoshinori; Kinomura, Nobukazu; Mano, Takayuki; Nishimoto, Shunsuke; Kameshima, Yoshikazu; Miyake, Michihiro

    2011-08-15

    LiBiO{sub 3}, NaBiO{sub 3}, MgBi{sub 2}O{sub 6}, KBiO{sub 3}, ZnBi{sub 2}O{sub 6}, SrBi{sub 2}O{sub 6}, AgBiO{sub 3}, BaBi{sub 2}O{sub 6} and PbBi{sub 2}O{sub 6} were synthesized by various processes such as hydrothermal treatment, heating and so on. These materials were examined for their photocatalytic activities in the decolorization of methylene blue and decomposition of phenol under visible light irradiation. For methylene blue decolorization, the presence of KBiO{sub 3} resulted in complete decoloration within 5 min. For phenol decomposition, NaBiO{sub 3} showed the highest activity, while LiBiO{sub 3}, SrBi{sub 2}O{sub 6} and BaBi{sub 2}O{sub 6} possessed almost comparable decomposition rates. Their decomposition rates were apparently higher than that by anatase (P25) under UV irradiation. - Graphical abstract: Nine pentavalent bismuthates were synthesized and were examined for their photocatalytic activities by decomposition of phenol under visible light irradiation. NaBiO{sub 3}, LiBiO{sub 3}, SrBi{sub 2}O{sub 6} and BaBi{sub 2}O{sub 6} indicated faster decomposition rate than that of anatase (P25) under UV-vis light irradiation. Highlights: > KBiO{sub 3} decolorize methylene blue aqueous solution immediately within 5 min. > NaBiO{sub 3}, LiBiO{sub 3}, SrBi{sub 2}O{sub 6} and BaBi{sub 2}O{sub 6} indicated high decomposition rate of phenol. > The d electron of Zn, Ag and Pb form broad conduction band. > The broad conduction band poses to diminish photocatalytic activity.

  3. Study of irradiation damage induced by He2+ ion irradiation in Ni62Ta38 metallic glass and W metal

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaonan; Mei, Xianxiu; Zhang, Qi; Li, Xiaona; Wang, Yingmin; Wang, Younian

    2017-09-01

    Metallic glasses are considered to possess good resistant against irradiation due to their inherent structural long-range disorder and a lack of grain boundaries. The He2+ with an energy of 300 keV was used to irradiate Ni62Ta38 binary metallic glass to investigate its resistance against the irradiation, and the irradiated behaviour of the metallic glass was compared with that of W metal. The irradiation fluence range over 2.0 × 1017 ions/cm2-1.6 × 1018 ions/cm2. The TEM results show that nanocrystals of μ-NiTa phase and Ni2Ta phase appeared in Ni62Ta38 metallic glass under the irradiation fluence of 1.6 × 1018 ions/cm2. The SEM results show that the surfaces of Ni62Ta38 metallic glasses maintained flat and smooth, whereas a large area of blisters with peeling formed on the surface of W metal at the irradiation fluence of 1.0 × 1018 ions/cm2. It indicates that the critical irradiation fluence of surface breakage of the Ni62Ta38 metallic glass is higher than that of W metal. After the irradiation, stress was generated in the surface layer of W metal, leading to the increase of the hardness of W metal.

  4. The influence of carbon ion irradiation on sweet sorghum seeds

    NASA Astrophysics Data System (ADS)

    Dong, X. C.; Li, W. J.; Liu, Q. F.; He, J. Y.; Yu, L. X.; Zhou, L. B.; Qu, Y.; Xie, H. M.

    2008-01-01

    The aim of this study is to investigate the effects of different doses of 100 MeV/u carbon ions on sweet sorghum seeds in order to improve crop yields and their sugar content. After irradiation, seeds were germinated and grown to 30 days, and others were sown in the field. At the end of harvesting season all planted seeds were picked separately and M2 generations obtained. The differences among the treatments were examined using the RAPD procedure. In the study done by using 38 primers; according to the amplification results, the differences among the various doses treatment were shown.

  5. Development of Nanoporous Polymer Membranes by Swift Heavy Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Dinesh, Divya; Predeep, P.

    2011-10-01

    This study reveals the preparation of conical pores in polyethylene terephthalate (PET) by track etching. The polymer membrane is etched from one side by keeping between the clamps of conductivity cell followed by irradiation with swift heavy ion of 197Au. Electrical stopping supports chemical stopping. During etching process current is measured as a function of time till a sharp increase -breakthrough-observed. After etching membranes are thoroughly washed with stopping solution and water. Resultant films are characterized using Optical microscope and field emission scanning electron microscopy. Polymer films with uniform pores can be a cheaper templating material in the fields of photonic crystals and micro- electronics.

  6. Track creation after swift heavy ion irradiation of insulators

    NASA Astrophysics Data System (ADS)

    Medvedev, N.; Osmani, O.; Rethfeld, B.; Schleberger, M.

    2010-10-01

    The dynamics of structural modifications of insulators irradiated with swift heavy ions were investigated theoretically applying a combination of Monte-Carlo method (MC), used to describe SHI penetration and following excitation and relaxation of the electronic subsystem, with Two Temperature Model (TTM) describing the heating of the lattice. This MC-TTM combination demonstrates that secondary ionizations play a very important role for the track formation process. They lead to an additional term in the heat diffusion equation related to energy stored in the hole subsystem. This storage of energy causes a significant delay of heating and prolongs the timescales up to tens of picoseconds.

  7. DNA damage in mammalian cells following heavy-ion irradiation

    SciTech Connect

    Rosander, K.; Frankel, K.A.; Cerda, H.; Phillips, M.H.; Lo, E.H.; Fabrikant, I.; Fabrikant, J.I.; Levy, R.P.

    1989-09-01

    In our laboratory we have been investigating DNA damage and repair in the endothelial and oligodendroglial cells of the mouse brain after irradiation using two different types of heavy ions, helium and neon. The method used, the unwinding technique with subsequent staining of the DNA with acridine orange, has been proven to be useful for nondividing cells and analysis using a microscope photometric technique. Our primary goal has been to obtain a measure of RBE, in the dose range used in clinical treatment of various brain disorders using heavy charged particle radiosurgery. 12 refs., 5 figs.

  8. Ion-irradiation-induced hardening in Inconel 718

    NASA Astrophysics Data System (ADS)

    Hunn, J. D.; Lee, E. H.; Byun, T. S.; Mansur, L. K.

    2001-07-01

    Inconel 718 is a material under consideration for areas in the target region of the spallation neutron source (SNS), now under construction at Oak Ridge National Laboratory (ORNL) in the US. In these positions, displacement damage from protons and neutrons will affect the mechanical properties. In addition, significant amounts of helium and hydrogen will build up in the material due to transmutation reactions. Nanoindentation measurements of solution-annealed (SA) Inconel 718 specimens, implanted with Fe-, He-, and H-ions to simulate SNS target radiation conditions, have shown that hardening occurs due to ion-induced displacement damage as well as due to the build-up of helium bubbles in the irradiated layer. Precipitation-hardened (PH) Inconel 718 also exhibited hardening by helium build-up but showed softening as a function of displacement damage due to dissolution of the γ ' and γ″ precipitates.

  9. Texture coefficient analysis of ion beam irradiated copper nanowires

    NASA Astrophysics Data System (ADS)

    Rana, Pallavi; Chaudhary, Ritika; Chauhan, R. P.

    2016-05-01

    Radiation may deteriorate physical properties of the materials and leave negative as well as positive impacts especially on crystalline materials. The energy deposited by ions to the grains and grain boundaries could also influence other properties of grains like: strain, reflection of charge carriers from grain boundaries, in addition to their grain size and orientation. The intensity of a peak in the XRD spectra is the direct reflection of orientation of a miller plane in the crystal. The increased intensity symbolizes the crystalline behavior due to defects annealing, while decreased intensity portray the defects formation and slender amorphisation. Orientation distribution function is a probability distribution function that quantified the texture of a polycrystalline material. The coefficients of harmonic expansion of orientation distribution function is the measurement of the texture coefficient `TC'. This study focused on the investigation of effect of ion beam irradiation on the preffered orientation of the planes of copper nanowires.

  10. Neovascular glaucoma after helium ion irradiation for uveal melanoma

    SciTech Connect

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

    1986-02-01

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

  11. Activity computer program for calculating ion irradiation activation

    NASA Astrophysics Data System (ADS)

    Palmer, Ben; Connolly, Brian; Read, Mark

    2017-07-01

    A computer program, Activity, was developed to predict the activity and gamma lines of materials irradiated with an ion beam. It uses the TENDL (Koning and Rochman, 2012) [1] proton reaction cross section database, the Stopping and Range of Ions in Matter (SRIM) (Biersack et al., 2010) code, a Nuclear Data Services (NDS) radioactive decay database (Sonzogni, 2006) [2] and an ENDF gamma decay database (Herman and Chadwick, 2006) [3]. An extended version of Bateman's equation is used to calculate the activity at time t, and this equation is solved analytically, with the option to also solve by numeric inverse Laplace Transform as a failsafe. The program outputs the expected activity and gamma lines of the activated material.

  12. Anderson localization of graphene by helium ion irradiation

    SciTech Connect

    Naitou, Y.; Ogawa, S.

    2016-04-25

    Irradiation of a single-layer graphene (SLG) with accelerated helium ions (He{sup +}) controllably generates defect distributions, which create a charge carrier scattering source within the SLG. We report direct experimental observation of metal-insulator transition in SLG on SiO{sub 2}/Si substrates induced by Anderson localization. This transition was investigated using scanning capacitance microscopy by monitoring the He{sup +} dose conditions on the SLG. The experimental data show that a defect density of more than ∼1.2% induced Anderson localization. We also investigated the localization length by determining patterned placement of the defects and estimated the length to be several dozen nanometers. These findings provide valuable insight for patterning and designing graphene-based nanostructures using helium ion microscopy.

  13. Texture coefficient analysis of ion beam irradiated copper nanowires

    SciTech Connect

    Rana, Pallavi Chaudhary, Ritika Chauhan, R. P.

    2016-05-23

    Radiation may deteriorate physical properties of the materials and leave negative as well as positive impacts especially on crystalline materials. The energy deposited by ions to the grains and grain boundaries could also influence other properties of grains like: strain, reflection of charge carriers from grain boundaries, in addition to their grain size and orientation. The intensity of a peak in the XRD spectra is the direct reflection of orientation of a miller plane in the crystal. The increased intensity symbolizes the crystalline behavior due to defects annealing, while decreased intensity portray the defects formation and slender amorphisation. Orientation distribution function is a probability distribution function that quantified the texture of a polycrystalline material. The coefficients of harmonic expansion of orientation distribution function is the measurement of the texture coefficient ‘TC’. This study focused on the investigation of effect of ion beam irradiation on the preffered orientation of the planes of copper nanowires.

  14. Depth distribution of Frank loop defects formed in ion-irradiated stainless steel and its dependence on Si addition

    NASA Astrophysics Data System (ADS)

    Chen, Dongyue; Murakami, Kenta; Dohi, Kenji; Nishida, Kenji; Soneda, Naoki; Li, Zhengcao; Liu, Li; Sekimura, Naoto

    2015-12-01

    Although heavy ion irradiation is a good tool to simulate neutron irradiation-induced damages in light water reactor, it produces inhomogeneous defect distribution. Such difference in defect distribution brings difficulty in comparing the microstructure evolution and mechanical degradation between neutron and heavy ion irradiation, and thus needs to be understood. Stainless steel is the typical structural material used in reactor core, and could be taken as an example to study the inhomogeneous defect depth distribution in heavy ion irradiation and its influence on the tested irradiation hardening by nano-indentation. In this work, solution annealed stainless steel model alloys are irradiated by 3 MeV Fe2+ ions at 400 °C to 3 dpa to produce Frank loops that are mainly interstitial in nature. The silicon content of the model alloys is also tuned to change point defect diffusion, so that the loop depth distribution influenced by diffusion along the irradiation beam direction could be discussed. Results show that in low Si (0% Si) and base Si (0.42% Si) samples the depth distribution of Frank loop density quite well matches the dpa profile calculated by the SRIM code, but in high Si sample (0.95% Si), the loop number density in the near-surface region is very low. One possible explanation could be Si's role in enhancing the effective vacancy diffusivity, promoting recombination and thus suppressing interstitial Frank loops, especially in the near-surface region, where vacancies concentrate. By considering the loop depth distribution, the tested irradiation hardening is successfully explained by the Orowan model. A hardening coefficient of around 0.30 is obtained for all the three samples. This attempt in interpreting hardening results may make it easier to compare the mechanical degradation between different irradiation experiments.

  15. Light ion velocities in the polar ionosphere

    NASA Technical Reports Server (NTRS)

    Murphy, J. A.; Heelis, R. A.

    1981-01-01

    High-speed flow of light ions along magnetic field lines is not simply a consequence of those field lines having an open topology. It is pointed out that the magnitude of the H(+) flow velocity in the polar wind is not predicted by theoretical models, but rather is imposed as a boundary condition. Thermal diffusion, the electron temperature profile, and a diverging magnetic field can be shown to have important effects on the H(+) flow velocity, which need not be supersonic even when the pressure at large distances from the earth is low.

  16. Ion irradiation induced disappearance of dislocations in a nickel-based alloy

    NASA Astrophysics Data System (ADS)

    Chen, H. C.; Li, D. H.; Lui, R. D.; Huang, H. F.; Li, J. J.; Lei, G. H.; Huang, Q.; Bao, L. M.; Yan, L.; Zhou, X. T.; Zhu, Z. Y.

    2016-06-01

    Under Xe ion irradiation, the microstructural evolution of a nickel based alloy, Hastelloy N (US N10003), was studied. The intrinsic dislocations are decorated with irradiation induced interstitial loops and/or clusters. Moreover, the intrinsic dislocations density reduces as the irradiation damage increases. The disappearance of the intrinsic dislocations is ascribed to the dislocations climb to the free surface by the absorption of interstitials under the ion irradiation. Moreover, the in situ annealing experiment reveals that the small interstitial loops and/or clusters induced by the ion irradiation are stable below 600 °C.

  17. Formation of long-range ordered quantum dots arrays in amorphous matrix by ion beam irradiation

    SciTech Connect

    Buljan, M.; Bogdanovic-Radovic, I.; Karlusic, M.; Desnica, U. V.; Radic, N.; Dubcek, P.; Drazic, G.; Salamon, K.; Bernstorff, S.; Holy, V.

    2009-08-10

    We demonstrate the production of a well ordered three-dimensional array of Ge quantum dots in amorphous silica matrix. The ordering is achieved by ion beam irradiation and annealing of a multilayer film. Structural analysis shows that quantum dots nucleate along the direction of the ion beam used for irradiation, while the mutual distance of the quantum dots is determined by the diffusion properties of the multilayer material rather than the distances between traces of ions that are used for irradiation.

  18. Magnetic force microscopy of nano-size magnetic domain ordering in heavy ion irradiated fullerene films.

    PubMed

    Kumar, Amit; Avasthi, D K; Pivin, J C; Papaléo, R M; Tripathi, A; Singh, F; Sulania, I

    2007-06-01

    In the present work, magnetic force microscopy is employed to investigate the magnetic ordering in ion irradiated fullerene films. It is observed that magnetic domain size is approximately 100-200 nm and magnetic signal is stronger at the domain boundaries. Magnetic signal arise in irradiated films is confirmed by magnetic measurements using a superconducting quantum interference device which increases with the ion fluence. The induced magnetism is possibly due to structural defects in the amorphous carbon phase formed by ion irradiation.

  19. Catalyst-free activation of peroxides under visible LED light irradiation through photoexcitation pathway.

    PubMed

    Gao, Yaowen; Li, Yixi; Yao, Linyu; Li, Simiao; Liu, Jin; Zhang, Hui

    2017-05-05

    Catalysts are known to activate peroxides to generate active radicals (i.e., hydroxyl radical (OH) and sulfate radical (SO4(-))) under certain conditions, but the activation of peroxides in the absence of catalysts under visible light irradiation has been rarely reported. This work demonstrates a catalyst-free activation of peroxides for the generation of OH and/or SO4(-) through photoexcited electron transfer from organic dyes to peroxides under visible LED light irradiation, where Rhodamine B (RhB) and Eosin Y (EY) were selected as model dyes. The formation of OH and/or SO4(-) in the reactions and the electron transfer from the excited dyes to peroxides were validated via electron paramagnetic resonance (EPR), photoluminescence (PL) spectra and cyclic voltammetry (CV). The performance of the peroxide/dye/Vis process was demonstrated to be altered depending on the target substrate. Meanwhile, the peroxide/dye/Vis process was effective for simultaneous decolorization of dyes and production of active radicals under neutral even or basic conditions. The findings of this study clarified a novel photoexcitation pathway for catalyst-free activation of peroxides under visible light irradiation, which could avoid the secondary metal ion (dissolved or leached) pollution from the metal-based catalysts and expand the application range of the peroxide-based catalytic process.

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

    SciTech Connect

    Yang, Tengfei; Taylor, Caitlin A.; Kong, Shuyan; Wang, Chenxu; Zhang, Yanwen; Huang, Xuejun; Xue, Jianming; Yan, Sha; Wang, Yugang

    2013-01-01

    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.

  1. Photocatalytic activities of various pentavalent bismuthates under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Takei, Takahiro; Haramoto, Rie; Dong, Qiang; Kumada, Nobuhiro; Yonesaki, Yoshinori; Kinomura, Nobukazu; Mano, Takayuki; Nishimoto, Shunsuke; Kameshima, Yoshikazu; Miyake, Michihiro

    2011-08-01

    LiBiO 3, NaBiO 3, MgBi 2O 6, KBiO 3, ZnBi 2O 6, SrBi 2O 6, AgBiO 3, BaBi 2O 6 and PbBi 2O 6 were synthesized by various processes such as hydrothermal treatment, heating and so on. These materials were examined for their photocatalytic activities in the decolorization of methylene blue and decomposition of phenol under visible light irradiation. For methylene blue decolorization, the presence of KBiO 3 resulted in complete decoloration within 5 min. For phenol decomposition, NaBiO 3 showed the highest activity, while LiBiO 3, SrBi 2O 6 and BaBi 2O 6 possessed almost comparable decomposition rates. Their decomposition rates were apparently higher than that by anatase (P25) under UV irradiation.

  2. Tailoring dynamic magnetic characteristics of F e60A l40 films through ion irradiation

    NASA Astrophysics Data System (ADS)

    Tahir, N.; Bali, R.; Gieniusz, R.; Mamica, S.; Gollwitzer, J.; Schneider, T.; Lenz, K.; Potzger, K.; Lindner, J.; Krawczyk, M.; Fassbender, J.; Maziewski, A.

    2015-10-01

    Magnetization dynamics in F e60A l40 thin films possessing depth-varying saturation magnetization (MS) have been studied experimentally and theoretically. Variation in MS was achieved by irradiation of 40 nm thick, chemically ordered (B2 phase) F e60A l40 films with N e+ ions with energies between 0-30 keV. The initial B2 phase is paramagnetic, and as the penetrating ions cause chemical disordering, the ion-affected region transforms to the ferromagnetic A2 phase. The effective ferromagnetic thickness and the depth of the A2/B2 phase boundary depend on the ion energy (E ); the effective thicknesses are 8.5 and 40 nm, respectively, for E =2.5 and 30 keV. Thermally excited spin waves in films with varying effective ferromagnetic thicknesses were analyzed by employing Brillouin light scattering and vector network analyzer ferromagnetic resonance spectroscopy. The analytical calculations are in good agreement with the experimental values and show that the observed spin-wave modes are directly related to the effective ferromagnetic thickness; films irradiated with E <15 keV only show the Damon-Eshbach mode, whereas for 15 ≤ E <20 keV , an additional lower frequency standing spin-wave mode is observed. In films irradiated with E ≥20 keV , the Damon-Eshbach mode is observed to lie between two standing spin-wave modes. Furthermore, the A2/B2 phase boundary can be shown to act as an asymmetric pinning site. Controlling the depth of the phase boundary by varying the ion energy can be a path to manipulate spin-wave propagation in materials displaying the phenomenon of disorder induced ferromagnetism.

  3. Irradiation of Materials using Short, Intense Ion Beams

    NASA Astrophysics Data System (ADS)

    Seidl, Peter; Ji, Q.; Persaud, A.; Feinberg, E.; Silverman, M.; Sulyman, A.; Waldron, W. L.; Schenkel, T.; Barnard, J. J.; Friedman, A.; Grote, D. P.; Gilson, E. P.; Kaganovich, I. D.; Stepanov, A.; Zimmer, M.

    2016-10-01

    We present experiments studying material properties created with nanosecond and millimeter-scale ion beam pulses on the Neutralized Drift Compression Experiment-II at Berkeley Lab. The explored scientific topics include the dynamics of ion induced damage in materials, materials synthesis far from equilibrium, warm dense matter and intense beam-plasma physics. We describe the improved accelerator performance, diagnostics and results of beam-induced irradiation of thin samples of, e.g., tin and silicon. Bunches with >3x1010 ions/pulse with 1-mm radius and 2-30 ns FWHM duration and have been created. To achieve the short pulse durations and mm-scale focal spot radii, the 1.2 MeV He+ ion beam is neutralized in a drift compression section which removes the space charge defocusing effect during the final compression and focusing. Quantitative comparison of detailed particle-in-cell simulations with the experiment play an important role in optimizing the accelerator performance and keep pace with the accelerator repetition rate of <1/minute. This work was supported by the Office of Science of the US Department of Energy under contracts DE-AC0205CH11231 (LBNL), DE-AC52-07NA27344 (LLNL) and DE-AC02-09CH11466 (PPPL).

  4. Simulation of alpha decay of actinides in iron phosphate glasses by ion irradiation

    NASA Astrophysics Data System (ADS)

    Dube, Charu L.; Stennett, Martin C.; Gandy, Amy S.; Hyatt, Neil C.

    2016-03-01

    A surrogate approach of ion beam irradiation is employed to simulate alpha decay of actinides in iron phosphate nuclear waste glasses. Bismuth and helium ions of different energies have been selected for simulating glass matrix modification owing to radiolysis and ballistic damage due to recoil atoms. Structural modification and change in coordination number of network former were probed by employing Reflectance Fourier-Transform Infrared (FT-IR), and Raman spectroscopies as a consequence of ion irradiation. Depolymerisation is observed in glass sample irradiated at intermediate energy of 2 MeV. Helium blisters of micron size are seen in glass sample irradiated at low helium ion energy of 30 keV.

  5. Amorphisation of boron carbide under slow heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Gosset, D.; Miro, S.; Doriot, S.; Moncoffre, N.

    2016-08-01

    Boron carbide B4C is widely used as a neutron absorber in nuclear plants. Most of the post-irradiation examinations have shown that the structure of the material remains crystalline, in spite of very high atomic displacement rates. Here, we have irradiated B4C samples with 4 MeV Au ions with different fluences at room temperature. Transmission electron microscopy (TEM) and Raman spectroscopy have been performed. The Raman analyses show a high structural disorder at low fluence, around 10-2 displacements per atoms (dpa). However, the TEM observations show that the material remains crystalline up to a few dpa. At high fluence, small amorphous areas a few nanometers large appear in the damaged zone but the long range order is preserved. Moreover, the size and density of the amorphous zones do not significantly grow when the damage increases. On the other hand, full amorphisation is observed in the implanted zone at a Au concentration of about 0.0005. It can be inferred from those results that short range and long range damages arise at highly different fluences, that heavy ions implantation has drastic effects on the structure stability and that in this material self-healing mechanisms are active in the damaged zone.

  6. Nanostructured light-absorbing crystalline CuIn{sub (1–x)}Ga{sub x}Se{sub 2} thin films grown through high flux, low energy ion irradiation

    SciTech Connect

    Hall, Allen J.; Hebert, Damon; Rockett, Angus A.; Shah, Amish B.; Bettge, Martin

    2013-10-21

    A hybrid effusion/sputtering vacuum system was modified with an inductively coupled plasma (ICP) coil enabling ion assisted physical vapor deposition of CuIn{sub 1−x}Ga{sub x}Se{sub 2} thin films on GaAs single crystals and stainless steel foils. With <80 W rf power to the ICP coil at 620–740 °C, film morphologies were unchanged compared to those grown without the ICP. At low temperature (600–670 °C) and high rf power (80–400 W), a light absorbing nanostructured highly anisotropic platelet morphology was produced with surface planes dominated by (112){sub T} facets. At 80–400 W rf power and 640–740 °C, both interconnected void and small platelet morphologies were observed while at >270 W and above >715 °C nanostructured pillars with large inter-pillar voids were produced. The latter appeared black and exhibited a strong (112){sub T} texture with interpillar twist angles of ±8°. Application of a negative dc bias of 0–50 V to the film during growth was not found to alter the film morphology or stoichiometry. The results are interpreted as resulting from the plasma causing strong etching favoring formation of (112){sub T} planes and preferential nucleation of new grains, balanced against conventional thermal diffusion and normal growth mechanisms at higher temperatures. The absence of effects due to applied substrate bias suggests that physical sputtering or ion bombardment effects were minimal. The nanostructured platelet and pillar films were found to exhibit less than one percent reflectivity at angles up to 75° from the surface normal.

  7. Mutation induction in bacteria after heavy ion irradiation

    NASA Technical Reports Server (NTRS)

    Horneck, G.; Kozubek, S.

    1994-01-01

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

  8. Titanium dioxide visible light photocatalysis: surface association enables photocatalysis with visible light irradiation.

    PubMed

    Pitre, Spencer P; Yoon, Tehshik P; Scaiano, Juan C

    2017-04-13

    Titanium dioxide (TiO2) is a widely employed and inexpensive photocatalyst, but its use in organic synthesis has been limited by the short-wavelength ultraviolet irradiation typically used. We have discovered that TiO2 particles efficiently mediate photocatalytic radical cation Diels-Alder cycloadditions using a simple visible light source, enabled by the formation of a visible light absorbing complex of the substrate on the semiconductor surface.

  9. The Light Ion Biomedical Research Accelerator (LIBRA)

    SciTech Connect

    Gough, R.A.

    1987-03-01

    LIBRA is a concept to place a light-ion, charged-particle facility in a hospital environment, and to dedicate it to applications in biology and medicine. There are two aspects of the program envisaged for LIBRA: a basic research effort coupled with a program in clinical applications of accelerated charged particles. The operational environment to be provided for LIBRA is one in which both of these components can coexist and flourish, and one that will promote the transfer of technology and knowledge from one to the other. In order to further investigate the prospects for a Light Ion Biomedical Research Accelerator (LIBRA), discussions are underway with the Merritt Peralta Medical Center (MPMC) in Oakland, California, and the University of California at San Francisco (UCSF). In this paper, a brief discussion of the technical requirements for such a facility is given, together with an outline of the accelerator technology required. While still in a preliminary stage, it is possible nevertheless to develop an adequate working description of the type, size, performance and cost of the accelerator facilities required to meet the preliminary goals for LIBRA.

  10. In situ heavy ion irradiation studies of nanopore shrinkage and enhanced radiation tolerance of nanoporous Au

    NASA Astrophysics Data System (ADS)

    Li, Jin; Fan, C.; Ding, J.; Xue, S.; Chen, Y.; Li, Q.; Wang, H.; Zhang, X.

    2017-01-01

    High energy particle radiations induce severe microstructural damage in metallic materials. Nanoporous materials with a giant surface-to-volume ratio may alleviate radiation damage in irradiated metallic materials as free surface are defect sinks. Here we show, by using in situ Kr ion irradiation in a transmission electron microscope at room temperature, that nanoporous Au indeed has significantly improved radiation tolerance comparing with coarse-grained, fully dense Au. In situ studies show that nanopores can absorb and eliminate a large number of radiation-induced defect clusters. Meanwhile, nanopores shrink (self-heal) during radiation, and their shrinkage rate is pore size dependent. Furthermore, the in situ studies show dose-rate-dependent diffusivity of defect clusters. This study sheds light on the design of radiation-tolerant nanoporous metallic materials for advanced nuclear reactor applications.

  11. In situ heavy ion irradiation studies of nanopore shrinkage and enhanced radiation tolerance of nanoporous Au

    PubMed Central

    Li, Jin; Fan, C.; Ding, J.; Xue, S.; Chen, Y.; Li, Q.; Wang, H.; Zhang, X.

    2017-01-01

    High energy particle radiations induce severe microstructural damage in metallic materials. Nanoporous materials with a giant surface-to-volume ratio may alleviate radiation damage in irradiated metallic materials as free surface are defect sinks. Here we show, by using in situ Kr ion irradiation in a transmission electron microscope at room temperature, that nanoporous Au indeed has significantly improved radiation tolerance comparing with coarse-grained, fully dense Au. In situ studies show that nanopores can absorb and eliminate a large number of radiation-induced defect clusters. Meanwhile, nanopores shrink (self-heal) during radiation, and their shrinkage rate is pore size dependent. Furthermore, the in situ studies show dose-rate-dependent diffusivity of defect clusters. This study sheds light on the design of radiation-tolerant nanoporous metallic materials for advanced nuclear reactor applications. PMID:28045044

  12. In situ heavy ion irradiation studies of nanopore shrinkage and enhanced radiation tolerance of nanoporous Au

    DOE PAGES

    Li, Jin; Fan, Cuncai; Ding, Jie; ...

    2017-01-03

    High energy particle radiations induce severe microstructural damage in metallic materials. Nanoporous materials with a giant surface-to-volume ratio may alleviate radiation damage in irradiated metallic materials as free surface are defect sinks. We show, by using in situ Kr ion irradiation in a transmission electron microscope at room temperature, that nanoporous Au indeed has significantly improved radiation tolerance comparing with coarse-grained, fully dense Au. In situ studies show that nanopores can absorb and eliminate a large number of radiation-induced defect clusters. Meanwhile, nanopores shrink (self-heal) during radiation, and their shrinkage rate is pore size dependent. Furthermore, the in situ studiesmore » show dose-rate-dependent diffusivity of defect clusters. Our study sheds light on the design of radiation-tolerant nanoporous metallic materials for advanced nuclear reactor applications.« less

  13. Irradiation of 4H-SiC UV detectors with heavy ions

    SciTech Connect

    Kalinina, E. V. Lebedev, A. A.; Bogdanova, E.; Berenquier, B.; Ottaviani, L.; Violina, G. N.; Skuratov, V. A.

    2015-04-15

    Ultraviolet (UV) photodetectors based on Schottky barriers to 4H-SiC are formed on lightly doped n-type epitaxial layers grown by the chemical vapor deposition method on commercial substrates. The diode structures are irradiated at 25°C by 167-MeV Xe ions with a mass of 131 amu at a fluence of 6 × 10{sup 9} cm{sup −2}. Comparative studies of the optical and electrical properties of as-grown and irradiated structures with Schottky barriers are carried out in the temperature range 23–180°C. The specific features of changes in the photosensitivity and electrical characteristics of the detector structures are accounted for by the capture of photogenerated carriers into traps formed due to fluctuations of the conduction-band bottom and valence-band top, with subsequent thermal dissociation.

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

    SciTech Connect

    Nagatomi, T.; Kuwayama, T.; Takai, Y.; Yoshino, K.; Morita, Y.; Kitagawa, M.; Nishitani, M.

    2008-02-25

    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.

  15. Ion irradiation-induced swelling and hardening effect of Hastelloy N alloy

    NASA Astrophysics Data System (ADS)

    Zhang, S. J.; Li, D. H.; Chen, H. C.; Lei, G. H.; Huang, H. F.; Zhang, W.; Wang, C. B.; Yan, L.; Fu, D. J.; Tang, M.

    2017-06-01

    The volumetric swelling and hardening effect of irradiated Hastelloy N alloy were investigated in this paper. 7 MeV and 1 MeV Xe ions irradiations were performed at room temperature (RT) with irradiation dose ranging from 0.5 to 27 dpa. The volumetric swelling increases with increasing irradiation dose, and reaches up to 3.2% at 27 dpa. And the irradiation induced lattice expansion is also observed. The irradiation induced hardening initiates at low ion dose (≤1dpa) then saturates with higher ion dose. The irradiation induced volumetric swelling may be ascribed to excess atomic volume of defects. The irradiation induced hardening may be explained by the pinning effect where the defects can act as obstacles for the free movement of dislocation lines. And the evolution of the defects' size and number density could be responsible for the saturation of hardness.

  16. Surface ripple evolution by argon ion irradiation in polymers

    SciTech Connect

    Goyal, Meetika; Aggarwal, Sanjeev Sharma, Annu

    2016-03-21

    In this report, an attempt has been made to investigate the morphological evolution of nanoscale surface ripples on aliphatic (polypropylene, PP) and aromatic (polyethylene terephthalate, PET) polymeric substrates irradiated with 50 keV Ar{sup +} ions. The specimens were sputtered at off normal incidence of 30° with 5 × 10{sup 16} Ar{sup +} cm{sup −2}. The topographical features and structural behavior of the specimens were studied using Atomic Force Microscopy (AFM) and UV-Visible spectroscopy techniques, respectively. The Stopping and Range of Ions in Matter simulations were performed to calculate sputtering yield of irradiated PP and PET polymers. Sputtering yield of carbon atoms has been found to be smaller for PP (0.40) as compared to PET (0.73), which is attributed to the different structures of two polymers. AFM analysis demonstrates the evolution of ripple like features with amplitude (2.50 nm) and wavelength (690 nm) on PET while that of lower amplitude (1.50 nm) and higher wavelength (980 nm) on PP specimen. The disorder parameter (Urbach energy) has been found to increase significantly from 0.30 eV to 1.67 eV in case of PP as compared to a lesser increase from 0.35 eV to 0.72 eV in case of PET as revealed by UV-Visible characterization. A mutual correlation between ion beam sputtering induced topographical variations with that of enhancement in the disorder parameter of the specimens has been discussed.

  17. Crystallization of ultrathin W-Si multilayer structures by high-energy heavy ion irradiations

    SciTech Connect

    Marfaing, J.; Marine, W. ); Vidal, B. ); Toulemonde, M. ); Hage Ali, M.; Stoquert, J.P. )

    1990-10-22

    Ultrathin amorphous multilayers structures (1.55 nm bilayer period) were irradiated by high-energy heavy ion ({sup 127}I and {sup 238}U ions). Transmission electron microscopy study shows that the ion-material interaction in such a configuration leads to an irreversible transformation of the initial amorphous structures. In this letter, we report the first observation of the crystallization of the multilayers induced by the heavy ion irradiations with a subsequent formation of a new WSi structure. The crucial role of the electronic effects in the crystallization process is discussed relatively to the other phenomena induced under the ion irradiation.

  18. Overview of Light-Ion Beam Therapy

    SciTech Connect

    Chu, William T.

    2006-03-16

    In 1930, Ernest Orlando Lawrence at the University of California at Berkeley invented the cyclotron. One of his students, M. Stanley Livingston, constructed a 13-cm diameter model that had all the features of early cyclotrons, accelerating protons to 80 keV using less than 1 kV on a semi-circular accelerating electrode, now called the ''dee''. Soon after, Lawrence constructed the first two-dee 27-Inch (69-cm) Cyclotron, which produced protons and deuterons of 4.8 MeV. In 1939, Lawrence constructed the 60-Inch (150-cm) Cyclotron, which accelerated deuterons to 19 MeV. Just before WWII, Lawrence designed a 184-inch cyclotron, but the war prevented the building of this machine. Immediately after the war ended, the Veksler-McMillan principle of phase stability was put forward, which enabled the transformation of conventional cyclotrons to successful synchrocyclotrons. When completed, the 184-Inch Synchrocyclotron produced 340-MeV protons. Following it, more modern synchrocyclotrons were built around the globe, and the synchrocyclotrons in Berkeley and Uppsala, together with the Harvard cyclotron, would perform pioneering work in treatment of human cancer using accelerated hadrons (protons and light ions). When the 184-Inch Synchrocyclotron was built, Lawrence asked Robert Wilson, one of his former graduate students, to look into the shielding requirements for of the new accelerator. Wilson soon realized that the 184-Inch would produce a copious number of protons and other light ions that had enough energy to penetrate human body, and could be used for treatment of deep-seated diseases. Realizing the advantages of delivering a larger dose in the Bragg peak when placed inside deep-seated tumors, he published in a medical journal a seminal paper on the rationale to use accelerated protons and light ions for treatment of human cancer. The precise dose localization provided by protons and light ions means lower doses to normal tissues adjacent to the treatment volume

  19. Characterisation of dual ion beam irradiated yttria-stabilised zirconia by specific analytical techniques

    NASA Astrophysics Data System (ADS)

    Zhang, Yanwen; Wang, Xu; Liu, Shiyi; Tang, Meixiong; Zhao, Ziqiang

    2015-01-01

    The combined effect of dual ion beam irradiated yttria-stabilized zirconia was investigated through Rutherford backscattering spectrometry/channeling (RBS/C), high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). Compared with other experimental results of single ion beam irradiation, a multistep damage accumulation model can also explain the irradiation effects of dual ion beam. Irradiation damage created by Ar + He ions are simply additive and no synergy effect has been observed. The variation trends of step height and displacement damage are similar. The synergic effects of displacement damage between heavy recoil atoms and α-particle in nuclear waste matrices will not cause more serious damage than the sum of two kinds of ions. The two experimental damage peaks are consistent with those calculated using stopping and range of ions in matter (SRIM). Phase stability and irradiation resistance is further confirmed by high resolution transmission electron microscopy (HRTEM).

  20. Reliability studies on NPN RF power transistors under swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Pushpa, N.; Praveen, K. C.; Gnana Prakash, A. P.; Naik, P. S.; Cressler, John D.; Gupta, S. K.; Revannasiddaiah, D.

    2012-02-01

    NPN RF power transistors were irradiated with 140 MeV Si 10+ ions, 100 MeV F 8+ ions, 50 MeV Li 3+ ions and Co-60 gamma radiation in the dose range from 100 krad to 100 Mrad. The transistor characteristics are studied before and after irradiation from which the parameters such as Gummel characteristics, excess base current (Δ IB = IBpost - IBpre), dc current gain ( hFE), transconductance ( gm) and collector-saturation current ( ICSat) are determined. The degradation observed in the electrical characteristics is almost the same for different types of ion irradiated NPN RF power transistors with similar total doses although there is a large difference in the linear energy transfer (LET) of the ions. Further, it was observed more degradation in DC I- V characteristics of ion irradiated devices than the Co-60 gamma irradiated devices for higher doses.

  1. Gold nanoparticles formed directly on a membrane by ultraviolet light irradiation

    SciTech Connect

    Qian, Hui Chen, Jian; Shen, Wei-Zheng; Kawasaki, Masahiro; Egerton, Ray F.

    2015-06-08

    There have been numerous research efforts directed towards the synthesis of gold (Au) nanoparticles (NPs) and the understanding of their formation, so that their size, shape, and stability can be well controlled for desired applications. Here, we report a dry photo-reduced method of Au NP formation directly on a membrane, such as a carbon thin film or a quartz slide. The evolution of Au NP formation was revealed by ex-situ experiments in an aberration-corrected scanning transmission electron microscope. The membranes were immersed in Au{sup 3+} solution before being taken out and quickly dried in ambient air at room temperature, then irradiated with ultraviolet (UV) light with wavelengths of 189 nm and 254 nm in a low-pressure chamber. The results show that Au{sup 3+} ions and ion clusters self-assembled on the membrane surface before UV irradiation and that solid Au NPs with sizes of 3 nm–12 nm were formed after UV irradiation. Annealing at 40 °C for about 30 min helped to further stabilize the nanoparticles. The Au NPs were uniform and well dispersed, and should find applications in the electron microscopy field, for example.

  2. Depth profiles of fullerene in ion irradiated polyimide

    NASA Astrophysics Data System (ADS)

    Fink, D.; Klett, R.; Mathis, C.; Vacik, J.; Hnatowicz, V.; Chadderton, L. T.

    1995-05-01

    An analytical experimental technique is described which permits depth profiles of the fundamental molecule fullerene, C 60, to be determined in solids for low molecular concentrations. The method combines a procedure for the simultaneous marking and immobilizing of fullerene in organic solids, by means of lithium salt formation, with "neutron depth profiling" — a highly sensitive approach in determining specific depth distributions of 6Li. The new technique — fullerene tracer profiling (FTP) — is described in some detail, and results of the first experiments are discussed. Fullerene solutions have been introduced into both pristine and ion-irradiated samples of the polymer polyimide (PI). The C 60 depth distributions were then measured using fullerene tracer profiling. From the shapes of the depth distributions conclusions are drawn concerning the uptake of fullerene solutions by polymers and the mobility of fullerene. Fullerene does not penetrate unirradiated PI, but it does readily fill up latent tracks of energetic ions in this polymer. Depending on the specific ion track density, some 10 4 to 10 7 C 60 molecules can be identified as being present in a single track. The diffusion coefficient for C 60 is estimated to be at least 2 × 10 -12 to 2 × 10 -13 cm 2s -1, much higher than expected. This may be ascribed in part to the remarkable elastic deformability of the fullerene molecule in both kinetic and dynamic motion, and to the near perfect spherical geometry accompanying elimination of dangling bonds in simultaneously minimising the surface energy.

  3. Late degeneration in rabbit tissues after irradiation by heavy ions.

    PubMed

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

    1980-01-01

    In 1974, using the rabbit as a model, we began long-term experiments designed to help in the evaluation of the hazards to man from extended exposure to heavy ions in space. Such exposure would occur, for example, during the construction of solar power stations in stationary orbits or on round trips to Mars. Our experiments with 400 MeV/nucleon Ne ions and 570 MeV/nucleon Ar ions have shown that true late effects of a degenerative nature are manifested only years after irradiation. At the appropriate doses (the high end of the experimental dose range), the magnitudes of the late effects are comparable with those encountered in human patients given radiation therapy with neutrons. Such comparisons show that the rabbit experiments are applicable to man. Given that basis, the results from the low end of the experimental dose range lead to the conclusion that astronauts subjected to the radiation fluxes anticipated during flights of the above duration could experience late radiation effects one or more decades after exposure. Late degenerative changes will occur in tissues of the central nervous system, terminally differentiating systems and stem cell populations. The studies also indicate that individual tissues may be "prematurely aged" by radiation in the sense that the "life spans" of those tissues can be decreased without the appearance of malignancies.

  4. Elemental Boron for Efficient Carbon Dioxide Reduction under Light Irradiation.

    PubMed

    Liu, Guigao; Meng, Xianguang; Zhang, Huabin; Zhao, Guixia; Pang, Hong; Wang, Tao; Li, Peng; Kako, Tetsuya; Ye, Jinhua

    2017-03-24

    The photoreduction of CO2 is attractive for the production of renewable fuels and the mitigation of global warming. Herein, we report an efficient method for CO2 reduction over elemental boron catalysts in the presence of only water and light irradiation through a photothermocatalytic process. Owing to its high solar-light absorption and effective photothermal conversion, the illuminated boron catalyst experiences remarkable self-heating. This process favors CO2 activation and also induces localized boron hydrolysis to in situ produce H2 as an active proton source and electron donor for CO2 reduction as well as boron oxides as promoters of CO2 adsorption. These synergistic effects, in combination with the unique catalytic properties of boron, are proposed to account for the efficiency of the CO2 reduction. This study highlights the promise of photothermocatalytic strategies for CO2 conversion and also opens new avenues towards the development of related solar-energy utilization schemes.

  5. On the puzzling deactivation mechanism of thymine after light irradiation

    SciTech Connect

    Gonzalez, Leticia; Gonzalez-Vazquez, Jesus; Samoylova, Elena; Schultz, Thomas

    2008-12-08

    The possible deactivation mechanisms of thymine after UV light irradiation are reviewed in the light of theoretical calculations. Recent experiments reveal that three transient species with lifetimes in the fs, ps, and ns regime are present in thymine. The possibility of ground or excited state tautomerization is explored and discarded. The role of {pi}{sigma}* states, as well as of the proposed minimum of the {pi}{pi}* excited state surface are assessed. In view of the obtained calculations and results available from the literature, the measured time scales can be tentatively attributed to a model involving different conical intersections between the {pi}{pi}*, n{pi}*, and the electronic ground state, as well as deactivation via the triplet states. Time-resolved photoelectron experiments supported by theoretical calculations are proposed to appraise the validity of this model.

  6. Nickel nanowires mesh fabricated by ion beam irradiation-induced nanoscale welding for transparent conducting electrodes

    NASA Astrophysics Data System (ADS)

    Honey, S.; Ahmad, I.; Madhuku, M.; Naseem, S.; Maaza, M.; Kennedy, J. V.

    2017-07-01

    In this report, random nickel nanowires (Ni-NWs) meshes are fabricated by ions beam irradiation-induced nanoscale welding of NWs on intersecting positions. Ni-NWs are exposed to beam of 50 KeV Argon (Ar+) ions at various fluencies in the range ~1015 ions cm-2 to 1016 ions cm-2 at room temperature. Ni-NWs are welded due to accumulation of Ar+ ions beam irradiation-induced sputtered atoms on crossing positions. Ar+ ions irradiated Ni-NWs meshes are optically transparent and optical transparency is enhanced with increase in beam fluence of Ar+ ions. Ar+ ions beam irradiation-induced welded and optically transparent mesh is then exposed to 2.75 MeV hydrogen (H+) ions at fluencies 1  ×  1015 ions cm-2, 3  ×  1015 ions cm-2 and 1  ×  1016 ions cm-2 at room temperature. MeV H+ ions irradiation-induced local heat cause melting and fusion of NWs on intersecting points and eventually lead to reduce contact resistance between Ni-NWs. Electrical conductivity is enhanced with increase in beam fluence of H+ ions. These welded highly transparent and electrically conductive Ni-NWs meshes can be employed as transparent conducting electrodes in optoelectronic devices.

  7. Energetic Ion and Electron Irradiation of the Icy Galilean Satellites

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  8. Energetic Ion and Electron Irradiation of the Icy Galilean Satellites

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  9. Effect of electronic energy loss and irradiation temperature on color-center creation in LiF and NaCl crystals irradiated with swift heavy ions

    SciTech Connect

    Schwartz, K.; Trautmann, C.; Voss, K.-O.; Neumann, R.; Volkov, A. E.; Sorokin, M. V.; Lang, M.

    2008-07-01

    LiF and NaCl crystals were irradiated at 8 K and 300 K with various light and heavy ions (C, Ti, Ni, Kr, Sm, Au, Pb, and U) of kinetic energy between about 50 and 2600 MeV, providing electronic energy losses from 0.7 to 26.4 keV/nm. A cryostat installed at the beamline allowed in situ absorption spectroscopy and thermostimulated luminescence (TSL) measurements from 8 K upward. Creation of electron and hole color centers is analyzed as a function of irradiation temperature, fluence, and thermal and optical bleaching. Anion interstitials (I and H centers) were only observed in crystals irradiated at 8 K. These defects are unstable and disappear in the temperature range 10-100 K. For heavy ions (Au, U), the F-center accumulation efficiency at low fluences is larger at 8 K than at room temperature. The opposite effect is observed for light ions (C, Ti, Ni). The results are discussed within the frame of transient heating influencing separation or annealing of point defects.

  10. Magnetosomes extracted from Magnetospirillum magneticum strain AMB-1 showed enhanced peroxidase-like activity under visible-light irradiation.

    PubMed

    Li, Kefeng; Chen, Chuanfang; Chen, Changyou; Wang, Yuzhan; Wei, Zhao; Pan, Weidong; Song, Tao

    2015-05-01

    Magnetosomes are intracellular structures produced by magnetotactic bacteria and are magnetic nanoparticles surrounded by a lipid bilayer membrane. Magnetosomes reportedly possess intrinsic enzyme mimetic activity similar to that found in horseradish peroxidase (HRP) and can scavenge reactive oxygen species depending on peroxidase activity. Our previous study has demonstrated the phototaxis characteristics of Magnetospirillum magneticum strain AMB-1 cells, but the mechanism is not well understood. Therefore, we studied the relationship between visible-light irradiation and peroxidase-like activity of magnetosomes extracted from M. magneticum strain AMB-1. We then compared this characteristic with that of HRP, iron ions, and naked magnetosomes using 3,3',5,5'-tetramethylbenzidine as a peroxidase substrate in the presence of H2O2. Results showed that HRP and iron ions had different activities from those of magnetosomes and naked magnetosomes when exposed to visible-light irradiation. Magnetosomes and naked magnetosomes had enhanced peroxidase-like activities under visible-light irradiation, but magnetosomes showed less affinity toward substrates than naked magnetosomes under visible-light irradiation. These results suggested that the peroxidase-like activity of magnetosomes may follow an ordered ternary mechanism rather than a ping-pong mechanism. This finding may provide new insight into the function of magnetosomes in the phototaxis in magnetotactic bacteria.

  11. Dynamics of photogenerated nonequilibrium electronic states in Ar+-ion-irradiated SrTiO3

    NASA Astrophysics Data System (ADS)

    Kumar, Dushyant; Hossain, Z.; Budhani, R. C.

    2015-05-01

    A metallic surface is realized on stoichiometric and insulating (100) SrTiO3 by Ar+-ion irradiation. The sheet carrier density and Hall mobility of the layer are ˜4.0 ×1014cm-2 and ˜2 ×103cm2/Vs , respectively, at 15 K for the irradiation dose of ˜4.2 ×1018ions/cm2 . These samples display ultraviolet light sensitive photoconductivity (PC) which is enhanced abruptly below the temperature (≈100 K) where SrTiO3 crystal undergoes an antiferrodistortive cubic-to-tetragonal (Oh1→D4h 18 ) structural phase transition. This behavior of PC maps well with the temperature dependence of dielectric function and electric field induced conductivity. The longevity of the PC state also shows a distinct change below ≈100 K. At T >100 K its decay is thermally activated with an energy barrier of ≈36 meV, whereas at T <100 K it becomes independent of temperature. We have examined the effect of electrostatic gating on the lifetime of the PC state. One nontrivial result is the ambient temperature quenching of the photoconducting state by the negative gate field. This observation opens avenues for designing a solid state photoelectric switch. The origin and lifetime of the PC state are understood in the light of field effect induced band bending, defect dynamics, and thermal relaxation processes.

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

    SciTech Connect

    Buljan, M.; Karlusic, M.; Bogdanovic-Radovic, I.; Jaksic, M.; Radic, N.; Salamon, K.; Bernstorff, S.

    2012-09-03

    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.

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

    NASA Astrophysics Data System (ADS)

    Buljan, M.; Karlušić, M.; Bogdanović-Radović, I.; Jakšić, M.; Salamon, K.; Bernstorff, S.; Radić, N.

    2012-09-01

    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.

  14. Highly sensitive urea sensing with ion-irradiated polymer foils

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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.

  15. Sympathetic ophthalmia complicating helium ion irradiation of a choroidal melanoma

    SciTech Connect

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

    1987-11-01

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

  16. Incoherent twin boundary migration induced by ion irradiation in Cu

    NASA Astrophysics Data System (ADS)

    Li, N.; Wang, J.; Wang, Y. Q.; Serruys, Y.; Nastasi, M.; Misra, A.

    2013-01-01

    Grain boundaries can act as sinks for radiation-induced point defects. The sink capability is dependent on the atomic structures and varies with the type of point defects. Using high-resolution transmission electron microscopy, we observed that Σ3{112} incoherent twin boundary (ITB) in Cu films migrates under Cu3+ ion irradiation. Using atomistic modeling, we found that Σ3{112} ITB has the preferred sites for adsorbing interstitials and the preferential diffusion channels along the Shockley partial dislocations. Coupling with the high mobility of grain boundary Shockley dislocations within Σ3{112} ITB, we infer that Σ3{112} ITB migrates through the collective glide of grain boundary Shockley dislocations, driven by a concurrent reduction in the density of radiation-induced defects, which is demonstrated by the distribution of nearby radiation-induced defects.

  17. Magnetic strip patterns induced by focused ion beam irradiation

    SciTech Connect

    Makarov, D.; Tibus, S.; Rettner, C. T.; Thomson, T.; Terris, B. D.; Schrefl, T.; Albrecht, M.

    2008-03-15

    Focused ion beam exposure was used to locally alter the magnetic properties of a continuous Co/Pd multilayer film with perpendicular magnetic anisotropy. The saturation magnetization, coercivity, and magnetic anisotropy of the films can be tuned by Ga irradiation depending on exposure dose. As a result, a periodic strip pattern consisting of 80 nm wide exposed strips which are magnetically soft, separated by 170 nm wide magnetically hard, unexposed areas was created. Due to strong magnetostatic coupling between the strips, a number of magnetic domain configurations could be stabilized and these have been observed by magnetic force microscopy and magneto-optic Kerr effect measurements. The magnetic domain configurations and their reversal behavior were investigated by micromagnetic simulations as a function of exposure dose and strip period.

  18. X-ray photoelectron spectroscopy analysis of organic materials irradiated with gas cluster ion beam

    SciTech Connect

    Nakagiri, Motohiro; Toyoda, Noriaki; Yamada, Isao

    2011-01-07

    Irradiation effect of gas cluster ion beams (GCIB) on organic materials were studied with X-ray photoelectron spectroscopy by comparison to that with Ar-monomer ions. In the case of polyimide, the intensity of both N-C = O and -C-O- bond decreased with 500 eV Ar monomer ion irradiation. On the other hand, there was no significant change in the XPS spectra after Ar-GCIB irradiation. From the size-selected GCIB irradiation study, the damages in polyimide decreased with increasing the cluster size owing to the reduction of energy per atoms.

  19. Surface pattern formation during MeV energy ion beam irradiation

    SciTech Connect

    Srivastava, S. K.; Nair, K. G. M.; Kannan, R. Kamala; Kamruddin, M.; Panigrahi, B. K.; Tyagi, A. K.

    2012-06-05

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

  20. Simulation of radiation damage in minerals by sequential ion irradiations

    NASA Astrophysics Data System (ADS)

    Nakasuga, W. M.; Li, W.; Ewing, R. C.

    2015-12-01

    Radiation effects due to α-decay of U and Th and spontaneous fission of 238U control the production and recovery of the radiation-induced structure of minerals, as well as the diffusion of elements through the mineral host. However, details of how the damage microstructure is produced and annealed remain unknown. Our recent ion beam experiments demonstrate that ionizing radiation from the α-particle recovers the damage structure. Thus, the damage structure is not only the result of the thermal hisotry of the sample, but also of the complex interaction between ionizing and ballistic damage mechanisms. By combining ion irradiations with transmission electron microscopy (TEM), we have simulated the damage produced by α-decay and fission. The α-particle induced annealing has been simulated by in situ TEM observation of consecutive ion-irradiations: i.) 1 MeV Kr2+ (simulating 70 keV α-recoils induced damage), ii.) followed by 400 keV He+ (simulating 4.5 MeV α-particle induced annealing). Thus, in addition to the well-established effects of thermal annealing, the α-particle annealing effects, as evidenced by partical recrystallization of the originally, fully-amorphous apatite upon the α-particle irriadations, should also be considered when evaluating diffusion and release of elements, such as He. In addition, the fission track annealing has been simulated by a new sample preparation method that allows for direct observation of radiation damage recovery at each point along the length of latent tracks created by 80 MeV Xe ions (a typical fission fragment). The initial, rapid reduction in etched track length during isothermal annealing is explained by the rapid annealing of those sections of the track with smaller diameters, as observed directly by in situ TEM. In summary, the atomic-scale investigation of radiation damage in minerals is critical to understanding of the influence of raidation damage on diffusion and kinetics that are fundamental to geochronology.

  1. Ion irradiation effects on sooting flames by-products

    NASA Astrophysics Data System (ADS)

    Brunetto, R.; Pino, T.; Dartois, E.; Cao, A. T.; D'Hendecourt, L.; Strazzulla, G.; Bréchignac, Ph.

    2008-10-01

    Carbonaceous extraterrestrial matter is observed in a wide variety of astrophysical environments. Spectroscopic signatures reveal a large variety of chemical structure illustrating the rich carbon chemistry that occurs in space. In order to produce laboratory analogues of the carbonaceous cosmic dust, a new chemical reactor has been built in the Laboratoire de Photophysique Moléculaire. It is a low pressure flat burner providing flames of premixed hydrocarbon/oxygen gas mixtures, closely following the model system used by the combustion community. In such a device the flame is a one-dimensional chemical reactor offering a broad range of combustion conditions and sampling which allows production of many and various by-products. In the present work, we have studied the effect of ion irradiation (200-400 keV), at the Laboratorio di Astrofisica Sperimentale in Catania, on several samples, ranging from strongly aromatic to strongly aliphatic materials. Infrared and Raman spectra were monitored to follow the evolution of the films under study, and characterize the irradiation process-induced modifications.

  2. MeV single-ion beam irradiation of mammalian cells using the Surrey vertical nanobeam, compared with broad proton beam and X-ray irradiations

    NASA Astrophysics Data System (ADS)

    Prakrajang, K.; Jeynes, J. C. G.; Merchant, M. J.; Kirkby, K.; Kirkby, N.; Thopan, P.; Yu, L. D.

    2013-07-01

    As a part of a systematic study on mechanisms involved in physical cancer therapies, this work investigated response of mammalian cells to ultra-low-dose ion beam irradiation. The ion beam irradiation was performed using the recently completed nanobeam facility at the Surrey Ion Beam Centre. A scanning focused vertical ion nano-beam was applied to irradiate Chinese hamster V79 cells. The V79 cells were irradiated in two different beam modes, namely, focused single ion beam and defocused scanning broad ion beam of 3.8-MeV protons. The single ion beam was capable of irradiating a single cell with a precisely controlled number of the ions to extremely low doses. After irradiation and cell incubation, the number of surviving colonies as a function of the number of the irradiating ions was measured for the cell survival fraction curve. A lower survival for the single ion beam irradiation than that of the broad beam case implied the hypersensitivity and bystander effect. The ion-beam-induced cell survival curves were compared with that from 300-kV X-ray irradiation. Theoretical studies indicated that the cell death in single ion irradiation mainly occurred in the cell cycle phases of cell division and intervals between the cell division and the DNA replication. The success in the experiment demonstrated the Surrey vertical nanobeam successfully completed.

  3. Comparison of swelling for structural materials on neutron and ion irradiation

    SciTech Connect

    Loomis, B.A.

    1986-03-01

    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.

  4. Irradiation effects on secondary structure of protein induced by keV ions

    NASA Astrophysics Data System (ADS)

    Cui, F. Z.; Lin, Y. B.; Zhang, D. M.; Tian, M. B.

    2001-01-01

    Protein secondary structure changes by low-energy ion irradiation are reported for the first time. The selected system is 30 keV N + irradiation on bovine serum albumin (BSA). After irradiation at increasing fluences from 1.0×10 15 to 2.5×10 16 ion/cm 2, Fourier transform infrared spectra analysis was conducted. It was found that the secondary structures of BSA molecules were very sensitive to ion irradiation. Secondary conformations showed different trends of change during irradiation. With the increase of ion fluence from 0 to 2.5×10 16 ion/cm 2, the fraction of α-helix and β-turns decreased from 17 to 12%, and from 40 to 31%, respectively, while that of random coil and β-sheet structure increased from 18 to 27%, and from 25 to 30%, respectively. Possible explanations for the secondary conformational changes of protein are proposed.

  5. Concurrent in situ ion irradiation transmission electron microscope

    SciTech Connect

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

    2014-08-29

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

  6. Irradiation of a tin oxide nanometric powder with swift heavy ions

    NASA Astrophysics Data System (ADS)

    Berthelot, A.; Gourbilleau, F.; Dufour, C.; Domengès, B.; Paumier, E.

    2000-05-01

    Tin oxide nanometric powders have been irradiated with swift heavy ions (Ar, Cd, Ta, Pb and U) and observed by high resolution electron microscopy (HREM). Except for Ar ions, cylindrical tracks are visible. The mean track radius is all the more important since the electronic stopping power Se is high. Furthermore, the high-Se ions (Ta, Pb and U) create cylindrical holes, while in the case of Cd irradiations, a crystal-like contrast remains in the core track. Cylindrical holes correspond to a local zone where the maximum temperature calculated using the thermal spike model exceeds the boiling point. For Cd ion irradiations, a sputtering process is investigated.

  7. Producing metastable nanophase with sharp interface by means of focused ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Barna, Árpád; Kotis, László; Lábár, János; Osváth, Zoltán; Tóth, Attila L.; Menyhárd, Miklós; Zalar, Anton; Panjan, Peter

    2009-02-01

    Amorphous carbon/nickel double layers were irradiated by 30 keV Ga+ ions via focused ion beam. The effect of irradiation on the concentration distribution of all constituents was studied by Auger electron spectroscopy depth profiling and cross sectional transmission electron microscopy, while the morphology change of the sample was determined by atomic force microscopy. The Ga+ ion irradiation results in the formation of metastable Ni3C layer with a uniform thickness. The C/Ni3C and Ni3C/Ni interfaces were found to be sharp up to a fluence of 200 Ga+ ions/nm2.

  8. Layer-to-layer compression and enhanced optical properties of few-layer graphene nanosheet induced by ion irradiation

    NASA Astrophysics Data System (ADS)

    Shang, Zhen; Tan, Yang; Zhou, Shengqiang; Chen, Feng

    2016-08-01

    We report on the first experimental study of the layer-to-layer compression and enhanced optical properties of few-layer graphene nanosheet by applying ion irradiation. The deformation of graphene layers is investigated both theoretically and experimentally. It is observed that after the irradiation of energetic ion beams, the space between separate graphene layers is reduced due to layer-to-layer compression, resulting in tighter contact of the graphene sheet with the surface of the substrate. This processing enables enhanced interaction of the graphene with the evanescent-field wave near the surface, which induces reinforced polarization-dependent light absorption of the graphene. Utilizing the ion-bombarded graphene nanosheets as saturable absorbers, we have realized efficient Q-switched waveguide lasing with enhanced performance through the interaction of the graphene and evanescent field.

  9. Superlattice-like stacking fault array in ion-irradiated GaN

    SciTech Connect

    Ishimaru, Dr. Manabu; Usov, Igor Olegovich; Zhang, Yanwen; Weber, William J

    2012-01-01

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

  10. Secondary particle tracks generated by ion beam irradiation

    NASA Astrophysics Data System (ADS)

    García, Gustavo

    2015-05-01

    The Low Energy Particle Track Simulation (LEPTS) procedure is a powerful complementary tool to include the effect of low energy electrons and positrons in medical applications of radiation. In particular, for ion-beam cancer treatments provides a detailed description of the role of the secondary electrons abundantly generated around the Bragg peak as well as the possibility of using transmuted positron emitters (C11, O15) as a complement for ion-beam dosimetry. In this study we present interaction probability data derived from IAM-SCAR corrective factors for liquid environments. Using these data, single electron and positron tracks in liquid water and pyrimidine have been simulated providing information about energy deposition as well as the number and type of interactions taking place in any selected ``nanovolume'' of the irradiated area. In collaboration with Francisco Blanco, Universidad Complutense de Madrid; Antonio Mu noz, Centro de Investigaciones Energéticas Medioambientales y Tecnológicas and Diogo Almeida, Filipe Ferreira da Silva, Paulo Lim ao-Vieira, Universidade Nova de Lisboa. Supported by the Spanish and Portuguese governments.

  11. Space Charge Formation by Irradiation of Visible Light in Polyimide under DC Electric Stress

    NASA Astrophysics Data System (ADS)

    Tadokoro, Tomo; Motoyama, Takuo; Harada, Hiroshi; Tanaka, Yasuhiro; Takada, Tastuo; Maeno, Takashi

    Space Charge behavior in polyimide film under dc stress with visible light irradiation was studied using an improved measurement system of pulsed electro-acoustic (PEA) method. The PEA method has been widely used to observe a space charge distribution in various solid dielectric materials. We applied the method to investigate the interaction of visible light irradiation on space charge formation in dielectric materials under dc stress. It is well known that the conduction property in dielectric materials is sometimes affected by the light irradiation. The space charge formation is also said that it affects to the conduction current property in dielectrics. However the relationship between the space charge and the light irradiation haven't been clear yet. To observe the effect of the light irradiation on the space charge distribution in polyimide film, we measured the time dependent space charge distribution under dc stress with the irradiation of visible light from four kinds of LED light sources. From the results, it is found that the space charge is formed by the irradiation of light under dc stress, while it is not formed without the irradiation. Furthermore, it is also found that the charge distribution is strongly affected by the energy of the irradiated light.

  12. Reactive oxygen species production in mitochondria of human gingival fibroblast induced by blue light irradiation.

    PubMed

    Yoshida, Ayaka; Yoshino, Fumihiko; Makita, Tetsuya; Maehata, Yojiro; Higashi, Kazuyoshi; Miyamoto, Chihiro; Wada-Takahashi, Satoko; Takahashi, Shun-suke; Takahashi, Osamu; Lee, Masaichi Chang-il

    2013-12-05

    In recent years, it has become well known that the production of reactive oxygen species (ROS) induced by blue-light irradiation causes adverse effects of photo-aging, such as age-related macular degeneration of the retina. Thus, orange-tinted glasses are used to protect the retina during dental treatment involving blue-light irradiation (e.g., dental resin restorations or tooth bleaching treatments). However, there are few studies examining the effects of blue-light irradiation on oral tissue. For the first time, we report that blue-light irradiation by quartz tungsten halogen lamp (QTH) or light-emitting diode (LED) decreased cell proliferation activity of human gingival fibroblasts (HGFs) in a time-dependent manner (<5 min). Additionally, in a morphological study, the cytotoxic effect was observed in the cell organelles, especially the mitochondria. Furthermore, ROS generation induced by the blue-light irradiation was detected in mitochondria of HGFs using fluorimetry. In all analyses, the cytotoxicity was significantly higher after LED irradiation compared with cytotoxicity after QTH irradiation. These results suggest that blue light irradiation, especially by LED light sources used in dental aesthetic treatment, might have adverse effects on human gingival tissue. Hence, this necessitates the development of new dental aesthetic treatment methods and/or techniques to protect HGFs from blue light irradiation during dental therapy. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Light irradiation is a factor in the bactericidal activity of silver-loaded zeolite.

    PubMed

    Inoue, Yoshihiro; Kogure, Makoto; Matsumoto, Ken-ichiro; Hamashima, Hajime; Tsukada, Masamichi; Endo, Kazutoyo; Tanaka, Tatsuo

    2008-05-01

    Silver loaded zeolite (Ag-Z) was previously found to have effective bactericidal activity against Escherichia coli. To understand the mechanisms of bactericidal activity of Ag-Z, role of light irradiation was focused and investigated in this study. In this study, we focused on light irradiation. Antibacterial assay and spectroscopic study revealed that light irradiation enabled Ag-Z to reduce dioxygen to form a reactive oxygen species, which led to bactericidal activity. These results indicate that the onset of bactericidal activity can be controlled by light irradiation.

  14. Atomistic-Scale Simulations of Defect Formation in Graphene under Noble Gas Ion Irradiation.

    PubMed

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L; Iberi, Vighter; Cullen, David A; Vlassiouk, Ivan V; Belianinov, Alex; Jesse, Stephen; Sang, Xiahan; Ovchinnikova, Olga S; Rondinone, Adam J; Unocic, Raymond R; van Duin, Adri C T

    2016-09-27

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation with a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. Additionally, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He(+) irradiation and monovacancy (MV) defects for all other ion irradiations.

  15. Atomistic-scale simulations of defect formation in graphene under noble gas ion irradiation

    SciTech Connect

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L.; Iberi, Vighter; Cullen, David A.; Vlassiouk, Ivan V.; Belianinov, Alex; Jesse, Stephen; Sang, Xiahan; Ovchinnikova, Olga S.; Rondinone, Adam Justin; Unocic, Raymond R.; van Duin, Adri C. T.

    2016-08-17

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation with a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. In addition, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He+ irradiation and monovacancy (MV) defects for all other ion irradiations.

  16. Atomistic-scale simulations of defect formation in graphene under noble gas ion irradiation

    DOE PAGES

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L.; ...

    2016-08-17

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation withmore » a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. In addition, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He+ irradiation and monovacancy (MV) defects for all other ion irradiations.« less

  17. Atomistic-scale simulations of defect formation in graphene under noble gas ion irradiation

    SciTech Connect

    Yoon, Kichul; Rahnamoun, Ali; Swett, Jacob L.; Iberi, Vighter; Cullen, David A.; Vlassiouk, Ivan V.; Belianinov, Alex; Jesse, Stephen; Sang, Xiahan; Ovchinnikova, Olga S.; Rondinone, Adam Justin; Unocic, Raymond R.; van Duin, Adri C. T.

    2016-08-17

    Despite the frequent use of noble gas ion irradiation of graphene, the atomistic-scale details, including the effects of dose, energy, and ion bombardment species on defect formation, and the associated dynamic processes involved in the irradiations and subsequent relaxation have not yet been thoroughly studied. Here, we simulated the irradiation of graphene with noble gas ions and the subsequent effects of annealing. Lattice defects, including nanopores, were generated after the annealing of the irradiated graphene, which was the result of structural relaxation that allowed the vacancy-type defects to coalesce into a larger defect. Larger nanopores were generated by irradiation with a series of heavier noble gas ions, due to a larger collision cross section that led to more detrimental effects in the graphene, and by a higher ion dose that increased the chance of displacing the carbon atoms from graphene. Overall trends in the evolution of defects with respect to a dose, as well as the defect characteristics, were in good agreement with experimental results. In addition, the statistics in the defect types generated by different irradiating ions suggested that the most frequently observed defect types were Stone-Thrower-Wales (STW) defects for He+ irradiation and monovacancy (MV) defects for all other ion irradiations.

  18. Formation of TiO{sub 2} nanorods by ion irradiation

    SciTech Connect

    Zheng, X. D.; Ren, F. Cai, G. X.; Hong, M. Q.; Xiao, X. H.; Wu, W.; Liu, Y. C.; Li, W. Q.; Ying, J. J.; Jiang, C. Z.

    2014-05-14

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. Tailoring magnetism in CoNi films with perpendicular anisotropy by ion irradiation

    SciTech Connect

    Stanescu, D.; Ravelosona, D.; Mathet, V.; Chappert, C.; Samson, Y.; Beigne, C.; Gierak, J.; Bouhris, E.; Fullerton, E. E.

    2008-04-01

    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.

  1. A study of light ion accelerators for cancer treatment

    SciTech Connect

    Prelec, K.

    1997-07-01

    This review addresses several issues, such as possible advantages of light ion therapy compared to protons and conventional radiation, the complexity of such a system and its possible adaptation to a hospital environment, and the question of cost-effectiveness compared to other modalities for cancer treatment or to other life saving procedures. Characteristics and effects of different types of radiation on cells and organisms will be briefly described; this will include conventional radiation, protons and light ions. The status of proton and light ion cancer therapy will then be described, with more emphasis on the latter; on the basis of existing experience the criteria for the use of light ions will be listed and areas of possible medical applications suggested. Requirements and parameters of ion beams for cancer treatment will then be defined, including ion species, energy and intensity, as well as parameters of the beam when delivered to the target (scanning, time structure, energy spread). Possible accelerator designs for light ions will be considered, including linear accelerators, cyclotrons and synchrotrons and their basic features given; this will be followed by a review of existing and planned facilities for light ions. On the basis of these considerations a tentative design for a dedicated light ion facility will be suggested, a facility that would be hospital based, satisfying the clinical requirements, simple to operate and reliable, concluding with its cost-effectiveness in comparison with other modalities for treatment of cancer.

  2. MCNPX Extension for Using Light Ion Evaluated Nuclear Data Library.

    SciTech Connect

    PATRICK,; SAUVAN,

    2013-05-23

    Version 00 US DOE 10CFR810 Jurisdiction. MCUNED is an MCNPX extension that handles a light ion evaluated nuclear data library. Using MCUNED, all MCNPX simulations involving transport of light ion could be solved using evaluated libraries instead of MCNPX built-in models.

  3. Structural damage in InGaN induced by MeV heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, L. M.; Fadanelli, R. C.; Hu, P.; Zhao, J. T.; Wang, T. S.; Zhang, C. H.

    2015-08-01

    In0.18Ga0.82N films were irradiated with 4 MeV 84Kr and 8.9 MeV 209Bi ions to various fluences at room temperature. The irradiated films were analyzed by means of Rutherford backscattering/channeling (RBS/C) and high resolution X-ray diffraction (HRXRD). The RBS/C measurements show that under the irradiation conditions, the relative lattice disorder in the films, obtained from the normalized backscattering yield, exhibits a rapid increase in the range from ∼2% to 68%. There is also an increasing lattice expansion of the films with increasing ion fluence, as determined by the HRXRD measurements. At a comparable level of lattice disorder, the Kr irradiation leads to a more pronounced lattice expansion than the Bi irradiation. This may be attributed to a larger portion of the single interstitials in the films produced by the lighter Kr ion irradiation.

  4. An orthophosphate semiconductor with photooxidation properties under visible-light irradiation

    NASA Astrophysics Data System (ADS)

    Yi, Zhiguo; Ye, Jinhua; Kikugawa, Naoki; Kako, Tetsuya; Ouyang, Shuxin; Stuart-Williams, Hilary; Yang, Hui; Cao, Junyu; Luo, Wenjun; Li, Zhaosheng; Liu, Yun; Withers, Ray L.

    2010-07-01

    The search for active semiconductor photocatalysts that directly split water under visible-light irradiation remains one of the most challenging tasks for solar-energy utilization. Over the past 30 years, the search for such materials has focused mainly on metal-ion substitution as in In1-xNixTaO4 and (V-,Fe- or Mn-)TiO2 (refs 7,8), non-metal-ion substitution as in TiO2-xNx and Sm2Ti2O5S2 (refs 9,10) or solid-solution fabrication as in (Ga1-xZnx)(N1-xOx) and ZnS-CuInS2-AgInS2 (refs 11,12). Here we report a new use of Ag3PO4 semiconductor, which can harness visible light to oxidize water as well as decompose organic contaminants in aqueous solution. This suggests its potential as a photofunctional material for both water splitting and waste-water cleaning. More generally, it suggests the incorporation of p block elements and alkali or alkaline earth ions into a simple oxide of narrow bandgap as a strategy to design new photoelectrodes or photocatalysts.

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

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

    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 μm 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 + Ti 3Al) overlayer the decomposition of the TiAl compound and the formation of Ti 3Al 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.

  6. In Situ TEM Multi-Beam Ion Irradiation as a Technique for Elucidating Synergistic Radiation Effects.

    PubMed

    Taylor, Caitlin Anne; Bufford, Daniel Charles; Muntifering, Brittany Rana; Senor, David; Steckbeck, Mackenzie; Davis, Justin; Doyle, Barney; Buller, Daniel; Hattar, Khalid Mikhiel

    2017-09-29

    Materials designed for nuclear reactors undergo microstructural changes resulting from a combination of several environmental factors, including neutron irradiation damage, gas accumulation and elevated temperatures. Typical ion beam irradiation experiments designed for simulating a neutron irradiation environment involve irradiating the sample with a single ion beam and subsequent characterization of the resulting microstructure, often by transmission electron microscopy (TEM). This method does not allow for examination of microstructural effects due to simultaneous gas accumulation and displacement cascade damage, which occurs in a reactor. Sandia's in situ ion irradiation TEM (I³TEM) offers the unique ability to observe microstructural changes due to irradiation damage caused by concurrent multi-beam ion irradiation in real time. This allows for time-dependent microstructure analysis. A plethora of additional in situ stages can be coupled with these experiments, e.g., for more accurately simulating defect kinetics at elevated reactor temperatures. This work outlines experiments showing synergistic effects in Au using in situ ion irradiation with various combinations of helium, deuterium and Au ions, as well as some initial work on materials utilized in tritium-producing burnable absorber rods (TPBARs): zirconium alloys and LiAlO₂.

  7. Effects of Helium Ion Irradiation on Properties of Crystalline and Amorphous Multiphase Ceramic Coatings

    NASA Astrophysics Data System (ADS)

    Chen, Yong; Hu, Liangbin; Qiu, Changjun; He, Bin; Wang, Zhongchang

    2017-08-01

    The Al2O3-TiO2 crystalline and amorphous multiphase ceramic coatings were prepared on a martensitic steel by laser in situ reaction technique and impose irradiation with 200 keV He ions at different doses. The helium ion irradiation goes 1.55 μm deep from the surface of coating, and the displacement per atom (dpa) for the Al2O3-TiO2 coating is 20.0. When the irradiation fluency is 5 × 1017 ions/cm2, defects are identified in crystalline areas and there form interfacial areas in the coating. These crystal defects tend to migrate and converge at the interfaces. Moreover, helium ion irradiation is found to exert no effect on surface chemical composition and phase constitution of the coatings, while surface mechanical properties for the coatings after irradiation differ from those before irradiation. Further nano-indentation experiments reveal that surface nano-hardness of the Al2O3-TiO2 multiphase coatings decreases as the helium ions irradiation flux increases. Such Al2O3-TiO2 crystalline and amorphous multiphase ceramic coatings exhibit the strongest resistance against helium ion irradiation which shall be applied as candidate structural materials for accelerator-driven sub-critical system to handle the nuclear waste under extreme conditions.

  8. Effects of Helium Ion Irradiation on Properties of Crystalline and Amorphous Multiphase Ceramic Coatings

    NASA Astrophysics Data System (ADS)

    Chen, Yong; Hu, Liangbin; Qiu, Changjun; He, Bin; Wang, Zhongchang

    2017-06-01

    The Al2O3-TiO2 crystalline and amorphous multiphase ceramic coatings were prepared on a martensitic steel by laser in situ reaction technique and impose irradiation with 200 keV He ions at different doses. The helium ion irradiation goes 1.55 μm deep from the surface of coating, and the displacement per atom (dpa) for the Al2O3-TiO2 coating is 20.0. When the irradiation fluency is 5 × 1017 ions/cm2, defects are identified in crystalline areas and there form interfacial areas in the coating. These crystal defects tend to migrate and converge at the interfaces. Moreover, helium ion irradiation is found to exert no effect on surface chemical composition and phase constitution of the coatings, while surface mechanical properties for the coatings after irradiation differ from those before irradiation. Further nano-indentation experiments reveal that surface nano-hardness of the Al2O3-TiO2 multiphase coatings decreases as the helium ions irradiation flux increases. Such Al2O3-TiO2 crystalline and amorphous multiphase ceramic coatings exhibit the strongest resistance against helium ion irradiation which shall be applied as candidate structural materials for accelerator-driven sub-critical system to handle the nuclear waste under extreme conditions.

  9. Influence of high energy ion irradiation on fullerene derivative (PCBM) thin films

    NASA Astrophysics Data System (ADS)

    Sharma, Trupti; Singhal, Rahul; Vishnoi, Ritu; Lakshmi, G. B. V. S.; Biswas, S. K.

    2017-04-01

    The modifications produced by 55 MeV Si4+ swift heavy ion irradiation on the phenyl C61 butyric acid methyl ester (PCBM) thin films (thickness ∼ 100 nm) has been enlightened. The PCBM thin films were irradiated at 1 × 1010, 1 × 1011 and 1 × 1012 ions/cm2 fluences. After ion irradiation, the decreased optical band gap and FTIR band intensities were observed. The Raman spectroscopy reveals the damage produced by energetic ions. The morphological variation were investigated by atomic force microscopy and contact angle measurements and observed to be influenced by incident ion fluences. After 1011 ions/cm2 fluence, the overlapping of ion tracks starts and produced overlapping effects.

  10. Role of carrier concentration in swift heavy ion irradiation induced surface modifications

    NASA Astrophysics Data System (ADS)

    Gupta, Sushant; Ganesan, V.; Sulania, Indra; Das, B.

    2017-10-01

    Highly conducting SnO2 thin films were prepared by chemical spray pyrolysis technique. One set of as-deposited films were annealed in air for 2 h at 850 °C. These as-deposited and annealed SnO2 thin films were irradiated using gold ions with energy of 120 MeV at different fluences ranging from 1 × 1011 to 3 × 1013 ions/cm2. Electrical measurement shows that as-deposited SnO2 films are in conducting state with n = 3.164 ×1020cm-3 and annealed SnO2 films are in insulating state. The amorphized latent tracks are created only above a certain threshold value of Se, which directly depends on the free electron concentration (n). The electronic energy loss (Se) of 120 MeV Au9+ ions in SnO2 is greater than the threshold energy loss (Seth) required for the latent track/molten zone formation in annealed SnO2 thin film, but is less than Seth required for as-deposited SnO2 film. Therefore, the latent tracks/molten zones are formed in the annealed SnO2 film and not in the as-deposited SnO2 film. Thermal spike model is used for the calculation of threshold energy loss and radius of melted zone. The possible mechanism of the structural changes and surface microstructure evolutions is briefly discussed in the light of ion's energy relaxation processes and target's conductivity. The atomic force microscopy (AFM) study of films shows that the morphologies of irradiated films are linked with carrier concentration of target materials.

  11. Enhancement of photo sensor properties of nanocrystalline ZnO thin film by swift heavy ion irradiation

    SciTech Connect

    Mahajan, S. V.; Upadhye, D. S.; Bagul, S. B.; Shaikh, S. U.; Birajadar, R. B.; Siddiqui, F. Y.; Huse, N. P.; Sharma, R. B. E-mail: rps.phy@gmail.com

    2015-06-24

    Nanocrystalline Zinc Oxide (ZnO) thin film prepared by Low cost Successive Ionic Layer Adsorption and Reaction (SILAR) method. This film was irradiated by 120 MeV Ni{sup 7+} ions with the fluence of 5x10{sup 12}ions/cm{sup 2}. The X-ray diffraction study was shows polycrystalline nature with wurtzite structure. The optical properties as absorbance were determined using UV-Spectrophotometer and band gap was also calculated. The Photo Sensor nature was calculated by I-V characteristics with different sources of light 40W, 60W and 100W.

  12. Investigation of Au9+ swift heavy ion irradiation on CdS/CuInSe2 thin films

    NASA Astrophysics Data System (ADS)

    Joshi, Rajesh A.; Taur, Vidya S.; Singh, Fouran; Sharma, Ramphal

    2013-10-01

    In the present manuscript we report about the preparation of CdS/CuInSe2 heterojunction thin films by chemical ion exchange method and investigation of 120 MeV Au9+ swift heavy ions (SHI) irradiation effect on its physicochemical as well as optoelectronic properties. These pristine (as grown) samples are irradiated with 120 MeV Au9+ SHI of 5×1011 and 5×1012 ions/cm2 fluencies and later on characterized for structural, compositional, morphological, optical and I-V characteristics. X-ray diffraction (XRD) pattern obtained from pristine and irradiated films shows considerable modifications in peak intensity as well as rising of some new peaks, corresponding to In2Se3, Cu3Se2 and CuIn2Se3 materials. Transmission electron microscope (TEM) images show decrease in grain size upon increase in irradiation ion fluencies, which is also supported from the observation of random and uneven distribution of nano-grains as confirmed through scanning electron microscope (SEM) images. Presence of Cd, Cu, In, S and Se in energy dispersive X-ray spectrum analysis (EDAX) confirms the expected and observed elemental composition in thin films, the absorbance peaks are related to band to band transitions and spin orbit splitting while energy band gap is observed to increase from 1.36 for pristine to 1.53 eV for SHI irradiated thin films and I-V characteristics under illumination to 100 mW/cm2 light source shows enhancement in conversion efficiency from 0.26 to 1.59% upon irradiation.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  14. Microvessel reactivity changes in light-diode irradiation of blood (470 to 980 nm)

    NASA Astrophysics Data System (ADS)

    Petrishchev, Nikolai N.; Yantareva, Ludmila I.

    1998-01-01

    The effects of distant light diode irradiation with various spectrums of the trunk vessels on reactivity of microvessels in the small intestine mesentery treated with threshold doses of norepinephrine (NoE) are compared. The character of changes in reactivity of microvessels to NoE was found to depend on the wave length and irradiation dose. Ultraviolet irradiation (470 nm, 0.03 J/sm2) was noticed to increase reactivity of the vessels to NoE (vasoconstriction increase). In green light irradiation (540 nm, 0.3 J/sm2 sm2) no changes in reactivity were observed. Red light irradiation (670 nm, 2.0 J/sm2), infrared particular (980 nm, 1.0 J/sm2), lowered reactivity to NoE. Thus, noninvasive light-diode irradiation of the blood results in different systemic changes of endothelial dependent reactivity of microcirculation due to specify of photochemical processes involved.

  15. Short communication on "In-situ TEM ion irradiation investigations on U3Si2 at LWR temperatures"

    SciTech Connect

    Miao, Yinbin; Harp, Jason; Mo, Kun; Bhattacharya, Sumit; Baldo, Peter; Yacout, Abdellatif M.

    2016-11-21

    Here, the radiation-induced amorphization of U3Si2 was investigated by in-situ transmission electron microscopy using 1 MeV Kr ion irradiation. Both arc-melted and sintered U3Si2 specimens were irradiated at room temperature to confirm the similarity in their responses to radiation. The sintered specimens were then irradiated at 350 °C and 550 °C up to 7.2 × 1015 ions/cm2 to examine their amorphization behavior under light water reactor (LWR) conditions. U3Si2 remains crystalline under irradiation at LWR temperatures. Oxidation of the material was observed at high irradiation doses.

  16. A semi-analytical radiobiological model may assist treatment planning in light ion radiotherapy.

    PubMed

    Kundrát, Pavel

    2007-12-07

    A semi-analytical model of light ions' Bragg peaks is presented and used in conjunction with a detailed probabilistic radiobiological module to predict the biological effectiveness of light ion irradiation for hadrontherapy applications. The physical Bragg peak model is based on energy-loss calculations with the SRIM code and phenomenological formulae for the energy-loss straggling. Effects of nuclear reactions are accounted for on the level of reducing the number of primary particles only. Reaction products are not followed at all and their contribution to dose deposition is neglected. Beam widening due to multiple scattering and calculations of spread-out Bragg peaks are briefly discussed. With this simple physical model, integral depth-dose distributions are calculated for protons, carbon, oxygen and neon ions. A good agreement with published experimental data is observed for protons and lower energy ions (with ranges in water up to approximately 15 cm), while less satisfactory results are obtained for higher energy ions due to the increased role of nuclear reaction products, neglected in this model. A detailed probabilistic radiobiological module is used to complement the simple physical model and to estimate biological effectiveness along the penetration depth of Bragg peak irradiation. Excellent agreement is found between model predictions and experimental data for carbon beams, indicating potential applications of the present scheme in treatment planning in light ion hadrontherapy. Due to the semi-analytical character of the model, leading to high computational speed, applications are foreseen in particular in the fully biological optimization of multiple irradiation fields and intensity-modulated beams.

  17. Surface modification and adhesion improvement of PTFE film by ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Lee, S. W.; Hong, J. W.; Wye, M. Y.; Kim, J. H.; Kang, H. J.; Lee, Y. S.

    2004-06-01

    The polytetrafluoroethylene (PTFE) surfaces, modified by 1 kV Ar + or O 2+ ion beam irradiation, was investigated with in-situ X-ray photoelectron spectroscopy (XPS), scanning electron micrographs (SEM), atomic force microscopy (AFM) measurements. The surface of PTFE films modified by Ar + ion irradiation was carbonized and the surface roughness increased with increasing ion doses. The surface of PTFE films modified by both Ar + ion in O 2 atmosphere and O 2+ ion irradiation formed the oxygen function group on PTFE surface, and the surface roughness change was relatively small. The adhesion improvement in Ar + ion irradiated PTFE surface is attributed to mechanical interlocking due to the surface roughness and CF-radical, but that in Ar + ion irradiation in an O 2 atmosphere was contributed by the CO complex and CF-radical with mechanical interlocking. The CO complex and CF-radical in O 2+ ion irradiated surface contributed to the adhesion.

  18. Long-term oxidative degradation in polyethylene irradiated with ion beams

    NASA Astrophysics Data System (ADS)

    Hama, Yoshimasa; Oka, Toshitaka; Uchiyama, Junichi; Kanbe, Hidenori; Nabeta, Kenji; Yatagai, Fumio

    2001-07-01

    The long-term oxidative degradation for high density polyethylene (HDPE) irradiated with various ion-beams was studied. Such degradation was insignificant for low density polyethylene (LDPE) even if irradiation was carried out under the same condition as for HDPE. This is attributed to a hydroperoxide group as the initiator produced by the reaction of the allyl radical with oxygen. The relationship between the mechanical properties and the local transformation induced by ion-beam irradiation was investigated. It is seen that the depth profiles of the mechanical properties along the pathway of the injected ion correspond to that of the crosslinking induced in polyethylene.

  19. EPR analysis of the effects of accelerated carbon ion and fast neutron irradiations on table sugar.

    PubMed

    Mikou, M; Benzina, S; Bischoff, P; Denis, J M; Gueulette, J

    2009-09-01

    Table sugar samples were irradiated with accelerated carbon ions and fast neutrons. Electron paramagnetic resonance (EPR) analysis performed after the irradiation revealed a complex spectrum similar to that observed after gamma-ray irradiations. The total concentration of the paramagnetic centers induced by accelerated carbon ions and neutrons was proportional to the absorbed dose. Good stability of the produced free radicals was observed for a typical period of sugar storage. Sugar was more sensitive to accelerated carbon ions than to neutrons. The results show that table sugar can be a useful material for dosimetry in the case of a radiation accident.

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

    SciTech Connect

    Jin, Shuoxue; He, Xinfu; Li, Tiecheng; Ma, Shuli; Tang, Rui; Guo, Liping

    2012-10-15

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

  1. Spectroscopic study of energetic helium-ion irradiation effects on nuclear graphite tiles

    NASA Astrophysics Data System (ADS)

    Kim, Do Wan; Lee, K. W.; Choi, D. M.; Noh, S. J.; Kim, H. S.; Lee, Cheol Eui

    2016-02-01

    Helium ion-irradiation effects on the nuclear graphite tiles were studied in order to understand the structural modifications and damages that can be produced by fusion reaction in tokamaks. The surface morphological changes due to increasing dose of the irradiation were examined by the field-effect scanning electron microscopy, and X-ray photoelectron spectroscopy elucidated the changes in the shallow surface bonding configurations caused by the energetic irradiation. Raman spectroscopy revealed the structural defects and diamond-like carbon sites that increased with increasing irradiation dose, and the average inter-defect distance was found from the Raman peak intensities as a function of the irradiation dose.

  2. Dependence of photoinduced bending behavior of diarylethene crystals on irradiation wavelength of ultraviolet light.

    PubMed

    Kitagawa, Daichi; Tanaka, Rika; Kobatake, Seiya

    2015-11-07

    The dependence of the photoinduced bending behavior of diarylethene crystals on the ultraviolet light irradiation wavelength was investigated. When irradiated with 365 nm light, a crystal of 1,2-bis(5-methyl-2-phenyl-4-thiazolyl)perfluorocyclopentene (1a) bends toward the incident light. On the other hand, when irradiated with 380 nm light, the crystal of 1a first bends away from the light source and then bends toward the incident light. To explain this bending behavior, we propose a comprehensive mechanism based on the depth of the photochromic reaction from the crystal surface. This mechanism is successfully supported by the change of cell parameters associated with the photochromic reaction upon irradiation with 380 nm light, which was determined by in situ X-ray crystallographic analysis.

  3. Simulating the ballistic effects of ion irradiation in the binary collision approximation: A first step toward the ion mixing framework

    NASA Astrophysics Data System (ADS)

    Demange, G.; Antoshchenkova, E.; Hayoun, M.; Lunéville, L.; Simeone, D.

    2017-04-01

    Understanding ballistic effects induced by ion beam irradiation can be a key point for controlling and predicting the microstructure of irradiated materials. Meanwhile, the ion mixing framework suggests an average description of displacement cascades may be sufficient to estimate the influence of ballistic relocations on the microstructure. In this work, the BCA code MARLOWE was chosen for its ability to account for the crystal structure of irradiated materials. A first set of simulations was performed on pure copper for energies ranging from 0.5 keV to 20 keV. These simulations were validated using molecular dynamics (MD). A second set of simulations on AgCu irradiated by 1 MeV krypton ions was then carried out using MARLOWE only, as such energy is beyond reach for molecular dynamics. MARLOWE simulations are found to be in good agreement with experimental results, which suggests the predictive potential of the method.

  4. Modifying the electronic structure of semiconducting single-walled carbon nanotubes by Ar{sup +} ion irradiation

    SciTech Connect

    Tolvanen, Antti; Buchs, Gilles; Ruffieux, Pascal; Groening, Pierangelo; Groening, Oliver; Krasheninnikov, Arkady V.

    2009-03-15

    Local controllable modification of the electronic structure of carbon nanomaterials is important for the development of carbon-based nanoelectronics. By combining density-functional theory simulations with Ar-ion-irradiation experiments and low-temperature scanning tunneling microscopy and spectroscopy (STM/STS) characterization of the irradiated samples, we study the changes in the electronic structure of single-walled carbon nanotubes due to the impacts of energetic ions. As nearly all irradiation-induced defects look as nondistinctive hillocklike features in the STM images, we compare the experimentally measured STS spectra to the computed local density of states of the most typical defects with an aim to identify the type of defects and assess their abundance and effects on the local electronic structure. We show that individual irradiation-induced defects can give rise to single and multiple peaks in the band gap of the semiconducting nanotubes and that a similar effect can be achieved when several defects are close to each other. We further study the stability of defects and their evolution during STM measurements. Our results not only shed light on the abundance of the irradiation-induced defects in carbon nanotubes and their signatures in STS spectra but also suggest a way the STM can be used for engineering the local electronic structure of defected carbon nanotubes.

  5. The Influence of Visible Light Irradiation on Breakdown Strength in Polyimide

    NASA Astrophysics Data System (ADS)

    Motoyama, Takuo; Hamada, Nanako; Tanaka, Yasuhiro; Maeno, Takashi

    Space Charge behavior in polyimide film under dc stress with visible light irradiation was investigated out using a newly developed measurement system of the pulsed electro-acoustic (PEA) method. The PEA method has been widely used to observe a space charge distribution in various solid insulating materials. We applied the method to investigate the influence of visible light irradiation on space charge formation in insulating materials under DC stress. It is well known that a property of the conduction in insulating materials is affected by the irradiation of light. However the relationship between the space charge and the irradiation of light has not been clear yet. So, we have observed the effect of the light irradiation on the space charge distribution in polyimide film. In this research, we have found that the space charge formation and the decrease of breakdown strength depends on chemical structure and fundamental absorption of the polyimide.

  6. Ion irradiation induced structural modifications and increase in elastic modulus of silica based thin films

    NASA Astrophysics Data System (ADS)

    Shojaee, S. A.; Qi, Y.; Wang, Y. Q.; Mehner, A.; Lucca, D. A.

    2017-01-01

    Ion irradiation is an alternative to heat treatment for transforming organic-inorganic thin films to a ceramic state. One major shortcoming in previous studies of ion-irradiated films is the assumption that constituent phases in ion-irradiated and heat-treated films are identical and that the ion irradiation effect is limited to changes in composition. In this study, we investigate the effects of ion irradiation on both the composition and structure of constituent phases and use the results to explain the measured elastic modulus of the films. The results indicated that the microstructure of the irradiated films consisted of carbon clusters within a silica matrix. It was found that carbon was present in a non-graphitic sp2-bonded configuration. It was also observed that ion irradiation caused a decrease in the Si-O-Si bond angle of silica, similar to the effects of applied pressure. A phase transformation from tetrahedrally bonded to octahedrally bonded silica was also observed. The results indicated the incorporation of carbon within the silica network. A combination of the decrease in Si-O-Si bond angle and an increase in the carbon incorporation within the silica network was found to be responsible for the increase in the elastic modulus of the films.

  7. Ion irradiation induced structural modifications and increase in elastic modulus of silica based thin films

    PubMed Central

    Shojaee, S. A.; Qi, Y.; Wang, Y. Q.; Mehner, A.; Lucca, D. A.

    2017-01-01

    Ion irradiation is an alternative to heat treatment for transforming organic-inorganic thin films to a ceramic state. One major shortcoming in previous studies of ion-irradiated films is the assumption that constituent phases in ion-irradiated and heat-treated films are identical and that the ion irradiation effect is limited to changes in composition. In this study, we investigate the effects of ion irradiation on both the composition and structure of constituent phases and use the results to explain the measured elastic modulus of the films. The results indicated that the microstructure of the irradiated films consisted of carbon clusters within a silica matrix. It was found that carbon was present in a non-graphitic sp2-bonded configuration. It was also observed that ion irradiation caused a decrease in the Si-O-Si bond angle of silica, similar to the effects of applied pressure. A phase transformation from tetrahedrally bonded to octahedrally bonded silica was also observed. The results indicated the incorporation of carbon within the silica network. A combination of the decrease in Si-O-Si bond angle and an increase in the carbon incorporation within the silica network was found to be responsible for the increase in the elastic modulus of the films. PMID:28071696

  8. Effect of crystal orientation on hardness of He+ ion irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Huang, Shilin; Ran, Guang; Lei, Penghui; Chen, Nanjun; Wu, Shenghua; Li, Ning; Shen, Qiang

    2017-09-01

    The effect of crystal orientation on hardness in the as-received, irradiated and post-irradiation annealed tungsten samples was investigated using a nanoindenter. An effective irradiation method of He+ ions with a series of energy degraded from 200 keV to 20 keV was used to continuously irradiate polycrystalline tungsten at room temperature in order to obtain a relatively homogenous displacement damage and helium concentration from sample surface to a desired depth at a NEC 400 kV ion implanter. Some irradiated samples were then annealed at 900 °C. He+ ion irradiation induced hardness increase, oppositely for the post-irradiation annealing effect. Meanwhile, the hardness of the irradiated samples was decreased sharply in the initial stage of annealing from 0 to 1 h, and then slowed down in the latter stage from 1 h to 3 h. Crystal orientation had an obvious effect on the nanoindentation hardness. The (0 0 1)-oriented grains had highest hardness at the as-received and irradiated samples. During the annealing process, the hardness in the irradiated grains with (1 1 1) crystal orientation decreased more quickly than that in the (0 0 1)-oriented grains. The mechanism of the effect of crystal orientation on hardness was analyzed and discussed.

  9. Effect of ion irradiation on the surface, structural and mechanical properties of brass

    NASA Astrophysics Data System (ADS)

    Ahmad, Shahbaz; Bashir, Shazia; Ali, Nisar; Umm-i-Kalsoom; Yousaf, Daniel; Faizan-ul-Haq; Naeem, Athar; Ahmad, Riaz; Khlaeeq-ur-Rahman, M.

    2014-04-01

    Modifications to the surface, structural and mechanical properties of brass after ion irradiation have been investigated. Brass targets were bombarded by carbon ions of 2 MeV energy from a Pelletron linear accelerator for various fluences ranging from 56 × 1012 to 26 × 1013 ions/cm2. A scanning electron microscope and X-ray diffractometer were utilized to analyze the surface morphology and crystallographic structure respectively. To explore the mechanical properties e.g., yield stress, ultimate tensile strength and microhardness of irradiated brass, an universal tensile testing machine and Vickers microhardness tester were used. Scanning electron microscopy results revealed an irregular and randomly distributed sputter morphology for a lower ion fluence. With increasing ion fluence, the incoherently shaped structures were transformed into dendritic structures. Nano/micro sized craters and voids, along with the appearance of pits, were observed at the maximum ion fluence. From X-ray diffraction results, no new phases were observed to be formed in the brass upon irradiation. However, a change in the peak intensity and higher and lower angle shifting were observed, which represents the generation of ion-induced defects and stresses. Analyses confirmed modifications in the mechanical properties of irradiated brass. The yield stress, ultimate tensile strength and hardness initially decreased and then increased with increasing ion fluence. The changes in the mechanical properties of irradiated brass are well correlated with surface and crystallographic modifications and are attributed to the generation, augmentation, recombination and annihilation of the ion-induced defects.

  10. The effect of electron beam irradiation on silver-sodium ion exchange in silicate glasses

    NASA Astrophysics Data System (ADS)

    Sidorov, Alexander I.; Prosnikov, Mikhail A.

    2016-04-01

    It is shown experimentally that electron irradiation of sodium-silicate glasses makes possible the control of the subsequent ion exchange Ag+ ↔ Na+ process in a salt melt. The reason of this effect is the negatively charged regions formation in a glass volume during electron irradiation. The electric field, produced by these regions in glass volume, results in positive Na+ ions field migration into them. The spatial redistribution of Na+ ions results in the decrease of the ion exchange efficiency, or the ion exchange can be even blocked. This led to the decrease of the luminescence intensity of neutral silver molecular clusters in the irradiated zone, and effect on the silver nanoparticles formation during the subsequent thermal treatment. The observed effects can be used for the control of ion exchange processes during integrated optics devices fabrication, and for the electron-beam recording of optical information.

  11. Comparison in the effect of linear polarized near-infrared light irradiation and light exercise on shoulder joint flexibility.

    PubMed

    Demura, Shinichi; Noguchi, Takanori; Matsuzawa, Jinzaburo

    2006-07-01

    This study aimed at comparing the effect of linear polarized near-infrared light irradiation (PL irradiation) and bicycle exercise with 50%HRreserve on the flexibility of the shoulder joint. Placebo-controlled trial. Twenty-four healthy young adults (10 males: mean+/-SD, age 20.9+/-3.1 y, height 171.0+/-3.9 cm, body mass 63.4+/-3.5 kg and 14 females: age 21.2+/-1.7 y, height 162.0+/-7.8 cm, body mass 56.2+/-7.2 kg). PL-irradiation (100%, 1800 mW), placebo-irradiation (10%,180 mW), and light exercise (50%HRreserve) for 10 minutes. OUTCOME MEASUREMENTS AND RESULTS: The shoulder joint angles were measured twice-before and after each intervention. We measured the angles when the right shoulder joint extended forward and flexed backward maximally without support, and analyzed these shoulder joints and range of motion. Trial-to-trial reliability (intraclass correlations) of each joint angle was very high, over 0.98. All joint angles showed significant changes, and values in post-PL-irradiation and postlight exercise were significantly greater than that in postplacebo-irradiation. Shoulder forward flexion and backward extension angles had significantly greater change rates in PL-irradiation and light exercise than placebo-irradiation, and their range of motion angle was in the order of PL-irradiation, light exercise, and placebo-irradiation. It is suggested that PL-irradiation produces almost the same effect on shoulder joint range of motion as light exercise.

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

    SciTech Connect

    Chen, Huang-Chin; Teng, Kuang-Yau; Tang, Chen-Yau; Lin, I-Nan; Sundaravel, Balakrishnan; Amirthapandian, Sankarakumar

    2010-12-15

    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.

  13. An ion-exchange route for the synthesis of hierarchical In2S3/ZnIn2S4 bulk composite and its photocatalytic activity under visible-light irradiation.

    PubMed

    Mei, Zongwei; Ouyang, Shuxin; Tang, Dai-Ming; Kako, Tetsuya; Golberg, Dmitri; Ye, Jinhua

    2013-02-28

    In(2)S(3)/ZnIn(2)S(4) bulk composite was successfully synthesized through an ion-exchange route using NaInS(2) as a precursor. Compared with the constituent pure component (In(2)S(3) or ZnIn(2)S(4)), the photocatalytic H(2) evolution of the composite was greatly enhanced because of the efficient separation and migration of photoexcited carriers (electrons and holes) at the interface of the bulk composite.

  14. The light ion trough, the main trough, and the plasmapause

    NASA Technical Reports Server (NTRS)

    Taylor, H. A., Jr.; Walsh, W. J.

    1972-01-01

    Extensive observations of mid-latitude depletions in electron and total ion density by both direct and indirect techniques, have prompted numerous studies of the possible association between these troughs, observed in the F-region, the topside ionosphere, and the plasmapause. One basic problem arises, in that while the plasmapause was detected as a global phenomenon both by VLF and ion composition measurements, the electron and ion density troughs were identified primarily as nightside features. This problem, as well as the difficulty in explaining various inconsistencies in relating the position of the plasmapause and the ionization trough, is explained by a close examination of the ion composition. In particular, ion composition results from the polar orbiting OGO satellites identify the persistence of a pronounced light ion trough in H(+) and He(+) identified by order of magnitude decreases in the light ion concentrations.

  15. Radiation-Pressure Acceleration of Ion Beams from Nanofoil Targets: The Leaky Light-Sail Regime

    SciTech Connect

    Qiao, B.; Zepf, M.; Borghesi, M.; Dromey, B.; Geissler, M.; Karmakar, A.; Gibbon, P.

    2010-10-08

    A new ion radiation-pressure acceleration regime, the 'leaky light sail', is proposed which uses sub-skin-depth nanometer foils irradiated by circularly polarized laser pulses. In the regime, the foil is partially transparent, continuously leaking electrons out along with the transmitted laser field. This feature can be exploited by a multispecies nanofoil configuration to stabilize the acceleration of the light ion component, supplementing the latter with an excess of electrons leaked from those associated with the heavy ions to avoid Coulomb explosion. It is shown by 2D particle-in-cell simulations that a monoenergetic proton beam with energy 18 MeV is produced by circularly polarized lasers at intensities of just 10{sup 19} W/cm{sup 2}. 100 MeV proton beams are obtained by increasing the intensities to 2x10{sup 20} W/cm{sup 2}.

  16. Radiation-pressure acceleration of ion beams from nanofoil targets: the leaky light-sail regime.

    PubMed

    Qiao, B; Zepf, M; Borghesi, M; Dromey, B; Geissler, M; Karmakar, A; Gibbon, P

    2010-10-08

    A new ion radiation-pressure acceleration regime, the "leaky light sail," is proposed which uses sub-skin-depth nanometer foils irradiated by circularly polarized laser pulses. In the regime, the foil is partially transparent, continuously leaking electrons out along with the transmitted laser field. This feature can be exploited by a multispecies nanofoil configuration to stabilize the acceleration of the light ion component, supplementing the latter with an excess of electrons leaked from those associated with the heavy ions to avoid Coulomb explosion. It is shown by 2D particle-in-cell simulations that a monoenergetic proton beam with energy 18 MeV is produced by circularly polarized lasers at intensities of just 10¹⁹  W/cm². 100 MeV proton beams are obtained by increasing the intensities to 2 × 10²⁰  W/cm².

  17. Shaping laser accelerated ions for future applications - The LIGHT collaboration

    NASA Astrophysics Data System (ADS)

    Busold, S.; Almomani, A.; Bagnoud, V.; Barth, W.; Bedacht, S.; Blažević, A.; Boine-Frankenheim, O.; Brabetz, C.; Burris-Mog, T.; Cowan, T. E.; Deppert, O.; Droba, M.; Eickhoff, H.; Eisenbarth, U.; Harres, K.; Hoffmeister, G.; Hofmann, I.; Jaeckel, O.; Jaeger, R.; Joost, M.; Kraft, S.; Kroll, F.; Kaluza, M.; Kester, O.; Lecz, Z.; Merz, T.; Nürnberg, F.; Al-Omari, H.; Orzhekhovskaya, A.; Paulus, G.; Polz, J.; Ratzinger, U.; Roth, M.; Schaumann, G.; Schmidt, P.; Schramm, U.; Schreiber, G.; Schumacher, D.; Stoehlker, T.; Tauschwitz, A.; Vinzenz, W.; Wagner, F.; Yaramyshev, S.; Zielbauer, B.

    2014-03-01

    The generation of intense ion beams from high-intensity laser-generated plasmas has been the focus of research for the last decade. In the LIGHT collaboration the expertise of heavy ion accelerator scientists and laser and plasma physicists has been combined to investigate the prospect of merging these ion beams with conventional accelerator technology and exploring the possibilities of future applications. We report about the goals and first results of the LIGHT collaboration to generate, handle and transport laser driven ion beams. This effort constitutes an important step in research for next generation accelerator technologies.

  18. Radiation damage by light- and heavy-ion bombardment of single-crystal LiNbO₃

    DOE PAGES

    Huang, Hsu-Cheng; Zhang, Lihua; Malladi, Girish; ...

    2015-04-14

    In this work, a battery of analytical methods including in situ RBS/C, confocal micro-Raman, TEM/STEM, EDS, AFM, and optical microscopy were used to provide a comparative investigation of light- and heavy-ion radiation damage in single-crystal LiNbO₃. High (~MeV) and low (~100s keV) ion energies, corresponding to different stopping power mechanisms, were used and their associated damage events were observed. In addition, sequential irradiation of both ion species was also performed and their cumulative depth-dependent damage was determined. It was found that the contribution from electronic stopping by high-energy heavy ions gave rise to a lower critical fluence for damage formationmore » than for the case of low-energy irradiation. Such energy-dependent critical fluence of heavy-ion irradiation is two to three orders of magnitude smaller than that for the case of light-ion damage. In addition, materials amorphization and collision cascades were seen for heavy-ion irradiation, while for light ion, crystallinity remained at the highest fluence used in the experiment. The irradiation-induced damage is characterized by the formation of defect clusters, elastic strain, surface deformation, as well as change in elemental composition. In particular, the presence of nanometric-scale damage pockets results in increased RBS/C backscattered signal and the appearance of normally forbidden Raman phonon modes. The location of the highest density of damage is in good agreement with SRIM calculations. (author)« less

  19. Radiation damage by light- and heavy-ion bombardment of single-crystal LiNbO₃

    DOE PAGES

    Huang, Hsu-Cheng; Zhang, Lihua; Malladi, Girish; ...

    2015-04-14

    In this work, a battery of analytical methods including in situ RBS/C, confocal micro-Raman, TEM/STEM, EDS, AFM, and optical microscopy were used to provide a comparative investigation of light- and heavy-ion radiation damage in single-crystal LiNbO₃. High (~MeV) and low (~100s keV) ion energies, corresponding to different stopping power mechanisms, were used and their associated damage events were observed. In addition, sequential irradiation of both ion species was also performed and their cumulative depth-dependent damage was determined. It was found that the contribution from electronic stopping by high-energy heavy ions gave rise to a lower critical fluence for damage formationmore » than for the case of low-energy irradiation. Such energy-dependent critical fluence of heavy-ion irradiation is two to three orders of magnitude smaller than that for the case of light-ion damage. In addition, materials amorphization and collision cascades were seen for heavy-ion irradiation, while for light ion, crystallinity remained at the highest fluence used in the experiment. The irradiation-induced damage is characterized by the formation of defect clusters, elastic strain, surface deformation, as well as change in elemental composition. In particular, the presence of nanometric-scale damage pockets results in increased RBS/C backscattered signal and the appearance of normally forbidden Raman phonon modes. The location of the highest density of damage is in good agreement with SRIM calculations. (author)« less

  20. The light ion LMF and its relevance to IFE

    SciTech Connect

    Olson, R.E.; Allshouse, G.O.; Cook, D.L.; Lockner, T.R.; Mazarakis, M.G.; Olson, C.L.; Smith, D.L.

    1993-12-01

    The inertial confinement fusion (ICF) program at Sandia National Laboratories (SNL) is directed toward validating light ions as an efficient driver for ICF defense and energy applications. The light ion laboratory microfusion facility (LMF) is envisioned as a facility in which high gain ICF targets could be developed and utilized in defense-related experiments. The relevance of LMF technology to eventual inertial fusion energy (IFE) applications is assessed via a comparison of LMF technologies with those projected in the Light Ion Beam Reactor Assessment (LIBRA) conceptual reactor design study.

  1. Low energy helium ion irradiation induced nanostructure formation on tungsten surface

    NASA Astrophysics Data System (ADS)

    Al-Ajlony, A.; Tripathi, J. K.; Hassanein, A.

    2017-05-01

    We report on the low energy helium ion irradiation induced surface morphology changes on tungsten (W) surfaces under extreme conditions. Surface morphology changes on W surfaces were monitored as a function of helium ion energy (140-300 eV), fluence (2.3 × 1024-1.6 × 1025 ions m-2), and flux (2.0 × 1020-5.5 × 1020 ion m-2 s-1). All the experiments were performed at 900° C. Our study shows significant effect of all the three ion irradiation parameters (ion flux, fluence, and energy) on the surface morphology. However, the effect of ion flux is more pronounced. Variation of helium ion fluence allows to capture the very early stages of fuzz growth. The observed fuzz growth and morphology changes were understood in the realm of various possible phenomena. The study has relevance and important impact in the current and future nuclear fusion applications.

  2. Radiation hardness of n-type SiC Schottky barrier diodes irradiated with MeV He ion microbeam

    NASA Astrophysics Data System (ADS)

    Pastuović, Željko; Capan, Ivana; Cohen, David D.; Forneris, Jacopo; Iwamoto, Naoya; Ohshima, Takeshi; Siegele, Rainer; Hoshino, Norihiro; Tsuchida, Hidekazu

    2015-04-01

    We studied the radiation hardness of 4H-SiC Schottky barrier diodes (SBD) for the light ion detection and spectroscopy in harsh radiation environments. n-Type SBD prepared on nitrogen-doped (∼4 × 1014 cm-3) epitaxial grown 4H-SiC thin wafers have been irradiated by a raster scanning alpha particle microbeam (2 and 4 MeV He2+ ions separately) in order to create patterned damage structures at different depths within a sensitive volume of tested diodes. Deep Level Transient Spectroscopy (DLTS) analysis revealed the formation of two deep electron traps in the irradiated and not thermally treated 4H-SiC within the ion implantation range (E1 and E2). The E2 state resembles the well-known Z1/2 center, while the E1 state could not be assigned to any particular defect reported in the literature. Ion Beam Induced Charge (IBIC) microscopy with multiple He ion probe microbeams (1-6 MeV) having different penetration depths in tested partly damaged 4H-SiC SBD has been used to determine the degradation of the charge collection efficiency (CCE) over a wide fluence range of damaging alpha particle. A non-linear behavior of the CCE decrease and a significant degradation of the spectroscopic performance with increasing He ion fluence were observed above the value of 1011 cm-2.

  3. The influence of fractionation on cell survival and premature differentiation after carbon ion irradiation.

    PubMed

    Wang, Jufang; Li, Renming; Guo, Chuanling; Fournier, Claudia; K-Weyrather, Wilma

    2008-07-01

    To investigate the influence of fractionation on cell survival and radiation induced premature differentiation as markers for early and late effects after X-rays and carbon irradiation. Normal human fibroblasts NHDF, AG1522B and WI-38 were irradiated with 250 kV X-rays, or 266 MeV/u, 195 MeV/u and 11 MeV/u carbon ions. Cytotoxicity was measured by a clonogenic survival assay or by determination of the differentiation pattern. Experiments with high-energy carbon ions show that fractionation induced repair effects are similar to photon irradiation. The RBE(10) values for clonogenic survival are 1.3 and 1.6 for irradiation in one or two fractions for NHDF cells and around 1.2 for AG1522B cells regardless of the fractionation scheme. The RBE for a doubling of post mitotic fibroblasts (PMF) in the population is 1 for both single and two fractionated irradiation of NHDF cells. Using 11 MeV/u carbon ions, no repair effect can be seen in WI-38 cells. The RBE(10) for clonogenic survival is 3.2 for single irradiation and 4.9 for two fractionated irradiations. The RBE for a doubling of PMF is 3.1 and 5.0 for single and two fractionated irradiations, respectively. For both cell lines the effects of high-energy carbon ions representing the irradiation of the skin and the normal tissue in the entrance channel are similar to the effects of X-rays. The fractionation effects are maintained. For the lower energy, which is representative for the irradiation of the tumor region, RBE is enhanced for clonogenic survival as well as for premature terminal differentiation. Fractionation effects are not detectable. Consequently, the therapeutic ratio is significantly enhanced by fractionated irradiation with carbon ions.

  4. Effect of Swift Heavy Ion Irradiation on Lithium Zinc Silicate Glasses: A Photoluminescence Study

    NASA Astrophysics Data System (ADS)

    Jogad, M. S.; Jogad, R. M.; Sudarsan, V.; Krishna, P. S. R.; Kothiyal, G. P.

    2011-07-01

    Lithium zinc silicate glasses with and without copper were prepared by melt-quench method and their luminescence characteristics after swift heavy ion irradiation has been investigated. Based on these studies it is established that both these glasses contain colour centres and the luminescence from such centres get significantly quenched once these samples get irradiated with 100 MeV swift heavy Ag+ ions with a fluence of 1013ions/cm2 at room temperature. Trapping of the charge carriers by the increased defect concentration brought about by irradiation is responsible for the decrease in the luminescence intensity from the irradiated samples. Copper in these glasses mainly exists as Cu+ ions as revealed by the broad emission around 500 nm.

  5. Molecular alteration and carbonization of aspartic acid upon N + ion irradiation

    NASA Astrophysics Data System (ADS)

    Cui, F. Z.; Sun, S. Q.; Zhang, D. M.; Ma, Z. L.; Chen, G. Q.

    2000-06-01

    Structural changes of aspartic acid (Asp) irradiated by nitrogen ions of 30 keV were studied using Fourier transform infrared (FTIR) spectroscopy. Significant decreases of the intensities of COO -, NH 3+, COOH and CH 2 vibrations in the FTIR spectra, compared with those of unirradiated Asp, were observed for the sample irradiated at the fluence of 1×10 16 ions/cm 2. The decrease rates of the intensities of COO -, NH 3+, COOH and CH 2 vibrations with respect to the increasing irradiation fluences up to 4×10 16 ions/cm 2 were different. The results were attributable to the nonstoichiometrical desorption of corresponding volatile species such as H 2, NH 3+ and CO 2. The radiolysis residue of Asp after irradiation at a high fluence of 1×10 17 ions/cm 2 was analyzed and fatty acid was detected.

  6. Investigation of Current Spike Phenomena During Heavy Ion Irradiation of NAND Flash Memories

    NASA Technical Reports Server (NTRS)

    Oldham, Timothy R.; Berg, Melanie; Friendlich, Mark; Wilcox, Ted; Seidleck, Christina; LaBel, Kenneth A.; Irom, Farokh; Buchner, Steven P.; McMorrow, Dale; Mavis, David G.; hide

    2011-01-01

    A series of heavy ion and laser irradiations were performed to investigate previously reported current spikes in flash memories. High current events were observed, however, none matches the previously reported spikes. Plausible mechanisms are discussed.

  7. Recovery effects due to the interaction between nuclear and electronic energy losses in SiC irradiated with a dual-ion beam

    SciTech Connect

    Thomé, Lionel Debelle, Aurélien; Garrido, Frédérico; Sattonnay, Gaël; Mylonas, Stamatis; Velisa, Gihan; Miro, Sandrine; Trocellier, Patrick; Serruys, Yves

    2015-03-14

    Single and dual-beam ion irradiations of silicon carbide (SiC) were performed to study possible Synergetic effects between Nuclear (S{sub n}) and Electronic (S{sub e}) Energy Losses. Results obtained combining Rutherford backscattering in channeling conditions, Raman spectroscopy, and transmission electron microscopy techniques show that dual-beam irradiation of SiC induces a dramatic change in the final sample microstructure with a substantial decrease of radiation damage as compared to single-beam irradiation. Actually, a defective layer containing dislocations is formed upon dual-beam irradiation (S{sub n} and S{sub e}), whereas single low-energy irradiation (S{sub n} alone) or even sequential (S{sub n} + S{sub e}) irradiations lead to full amorphization. The healing process is ascribed to the electronic excitation arising from the electronic energy loss of swift ions. These results shed new light on the long-standing puzzling problem of the existence of a possible synergy between S{sub n} and S{sub e} in ion-irradiation experiments. This work is interesting for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where recovery S{sub n}/S{sub e} effects may preserve the integrity of nuclear devices.

  8. Nano-porosity in GaSb induced by swift heavy ion irradiation

    SciTech Connect

    Kluth, P. Schnohr, C. S.; Giulian, R.; Araujo, L. L.; Lei, W.; Rodriguez, M. D.; Afra, B.; Bierschenk, T.; Ridgway, M. C.; Sullivan, J.; Weed, R.; Li, W.; Ewing, R. C.

    2014-01-13

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

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

    SciTech Connect

    Kumar, M. Vinay; Krishnakumar, K. S.; Dinesh, C. M.; Krishnaveni, S.; Ramani

    2012-06-05

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

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

    NASA Astrophysics Data System (ADS)

    Kumar, M. Vinay; Krishnakumar, K. S.; Dinesh, C. M.; Krishnaveni, S.; Ramani

    2012-06-01

    The radiation response of npn Bipolar junction transistor (BJT) has been examined for 100 MeV O7+ ion. Key electrical properties like Gummel characteristics, dc current gain and capacitance-voltage of 100MeV O7+ ion irradiated transistor were studied before and after irradiation. The device was decapped and the electrical characterizations were performed at room temperature. Base current is observed to be more sensitive than collector current and gain appears to be degraded with ion fluence, also considerable degradation in C-V characteristics is observed and doping concentration is found to be increased along with the increase in ion fluence.

  11. Superlattice-Like Stacking Fault Array in Ion-Irradiated GaN

    SciTech Connect

    Ishimaru, Manabu; Usov, Igor O.; Zhang, Yanwen; Weber, William J.

    2012-01-01

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

  12. Enhanced photocatalytic performance of BiVO4 in aqueous AgNO3 solution under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Huang, Chien-Kai; Wu, Tsunghsueh; Huang, Chang-Wei; Lai, Chi-Yung; Wu, Mei-Yao; Lin, Yang-Wei

    2017-03-01

    Monoclinic-phase bismuth vanadate (BiVO4) with a 2.468 eV band gap exhibited enhanced synergic photodegradation activity toward methylene blue (MB) when combined with silver ions (Ag+) in an aqueous solution under visible light irradiation. The mass ratio of AgNO3 to BiVO4 and the calcination temperature were discovered to considerably affect the degradation activity of BiVO4/Ag+. Superior photocatalytic performance was obtained when BiVO4 was mixed with 0.01%(w/v) AgNO3 solution, and complete degradation of MB was achieved after 25 min visible light irradiation, outperforming BiVO4 or AgNO3 solution alone. The enhanced photodegradation was investigated using systematic luminescence measurements, electrochemical impedance spectroscopy, and scavenger addition, after which a photocatalytic mechanism for MB degradation under visible light irradiation was identified that involved oxygen radicals and holes. This study also discovered the two dominating processes involved in enhancing the electron-hole separation efficiency and reducing their recombination rate, namely photoreduction of Ag+ and the formation of a BiVO4/Ag heterojunction. The synergic effect between BiVO4 and Ag+ was discovered to be unique. BiVO4/Ag+ was successfully used to degrade two other dyes and disinfect Escherichia Coli. A unique fluorescent technique using BiVO4 and a R6G solution to detect Ag+ ions in water was discovered.

  13. Magnetic patterning of Fe/Cr/Fe(001) trilayers by Ga{sup +} ion irradiation

    SciTech Connect

    Blomeier, S.; Hillebrands, B.; Demidov, V.E.; Demokritov, S.O.; Reuscher, B.; Brodyanski, A.; Kopnarski, M.

    2005-11-01

    Magnetic patterning of antiferromagnetically coupled epitaxial Fe (10 nm)/Cr (0.7 nm)/Fe (10 nm) (001) trilayers by irradiation with 30 keV Ga{sup +} ions was studied by means of atomic force microscopy, magnetic force microscopy, and Kerr magnetometry. It was found that within a fluence range of (1.25-5)x10{sup 16} ions/cm{sup 2} a complete transition from antiferromagnetic to ferromagnetic coupling between the two Fe layers can be achieved. The magnetization reversal processes of the nonirradiated, antiferromagnetically coupled areas situated close to the irradiated areas were studied with lateral resolution. Evidence for a lateral coupling mechanism between the magnetic moments of the irradiated and nonirradiated areas was found. Special attention was paid to preserve the flatness of the irradiated samples. Depending on the fluence, topographic steps ranging from +1.5 to -2 nm between the nonirradiated and irradiated areas were observed. At lower fluences the irradiation causes an increase of the surface height, while for higher fluences the height decreases. It was found that for the particular fluence of 2.7x10{sup 16} ions/cm{sup 2} no height difference between the irradiated and nonirradiated areas occurs. The results suggest that the irradiation of Fe/Cr/Fe trilayers with midenergy ions is an innovative method for magnetic patterning, preserving the initial smoothness of the sample.

  14. Water splitting on semiconductor catalysts under visible-light irradiation.

    PubMed

    Navarro Yerga, Rufino M; Alvarez Galván, M Consuelo; del Valle, F; Villoria de la Mano, José A; Fierro, José L G

    2009-01-01

    Sustainable hydrogen production is a key target for the development of alternative, future energy systems that will provide a clean and affordable energy supply. The Sun is a source of silent and precious energy that is distributed fairly all over the Earth daily. However, its tremendous potential as a clean, safe, and economical energy source cannot be exploited unless the energy is accumulated or converted into more useful forms. The conversion of solar energy into hydrogen via the water-splitting process, assisted by photo-semiconductor catalysts, is one of the most promising technologies for the future because large quantities of hydrogen can potentially be generated in a clean and sustainable manner. This Minireview provides an overview of the principles, approaches, and research progress on solar hydrogen production via the water-splitting reaction on photo-semiconductor catalysts. It presents a survey of the advances made over the last decades in the development of catalysts for photochemical water splitting under visible-light irradiation. The Minireview also analyzes the energy requirements and main factors that determine the activity of photocatalysts in the conversion of water into hydrogen and oxygen using sunlight. Remarkable progress has been made since the pioneering work by Fujishima and Honda in 1972, but he development of photocatalysts with improved efficiencies for hydrogen production from water using solar energy still faces major challenges. Research strategies and approaches adopted in the search for active and efficient photocatalysts, for example through new materials and synthesis methods, are presented and analyzed.

  15. Thermal annealing of vacancy and interstitial loops in ion irradiated copper

    SciTech Connect

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

    1985-01-01

    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.

  16. Application of ion beam irradiated ePTFE to repair small vessel injuries

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

    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.

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

    PubMed

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

    2010-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  19. SU-C-204-04: Irradiation of Human Cell Lines Using Various Ions

    SciTech Connect

    Lin, Y; McMahon, S; Kaminuma, T; Held, K; Tessa, C; Rusek, A

    2016-06-15

    Purpose: The purpose of this study is to investigate and quantify the biological effects of ion radiation using several human cell lines. We aim to answer the question of whether carbon ion the most ideal ion species for heavy ion radiotherapy. Methods: The cells were irradiated at different positions along the pristine Bragg peak of several ions with different atomic number. The biological effectiveness was evaluated using the clonogenic cell survival assay. Irradiation of three human lung cancer cell lines and a fibroblast cell line were undertaken using the charged particle beam at the NASA Space Radiation Laboratory at Brookhaven National Lab. Four mono-energetic ion beams (carbon, oxygen, helium and lithium) were used to irradiate the cells. Water or media-filled T25 flasks were lined up along the beam line so that the cell-containing surfaces of the flasks were placed at a specific depth along the pristine Bragg curve. Four depths along the curve, representing entrance point, rising peak, peak and distal fall off, were selected to determine biological effectiveness. Gaf-chromic films were placed between the flasks to monitor the irradiation as soon as it was finished. Results: For all ion radiations, the maximum cell killing effect occurs at either peak or distal fall off, depending on the cell lines. For instance, for the fibroblast cell line AGO1522, RBEs of 1.4, 1.2, 1.4 and 1.9 were observed at the Bragg peak for Helium, Lithium, Carbon and Oxygen ions. Comparing positions, RBEs of 0.9, 1.2, 1.4 and 1.8 were observed for carbon irradiation of AGO-1522 cells positions corresponding to entrance, rising peak, peak and distal fall off. Conclusion: RBE values differ with position in the Bragg peak, ion species and cell line. Ions other than carbon may prove more effective in certain irradiation conditions and may contribute to optimized heavy ion therapy.

  20. Targeted irradiation of biological cells using an ion microprobe - Why a small beam spot is not sufficient for success

    NASA Astrophysics Data System (ADS)

    Fischer, B. E.; Voss, K.-O.; Du, G.

    2009-06-01

    When people plan to adapt their ion microprobe for the targeted irradiation of biological cells, they often claim that they expect a targeting accuracy in the range of their beam spot diameter, because they assume that reaching a sub-μm beam spot is the most difficult part of the job. Although many microprobes have now a beam spot diameter of some hundred nano-meters or less, nobody reached a targeting accuracy below 1 μm. Besides obvious reasons, like mechanical or thermal instabilities, there is a more difficult problem to overcome: one still needs a light microscope to locate both the microbeam and the cells to be irradiated, and there are various light-optical effects, which can give misleading information about the position of the beam and the cells.

  1. Electrical properties of irradiated PVA film by using ion/electron beam

    NASA Astrophysics Data System (ADS)

    Abdelrahman, M. M.; Osman, M.; Hashhash, A.

    2016-02-01

    Ion/electron beam bombardment has shown great potential for improving the surface properties of polymers. Low-energy charged (ion/electron) beam irradiation of polymers is a good technique to modify properties such as electrical conductivity, structural behavior, and their mechanical properties. This paper reports on the effect of nitrogen and electron beam irradiation on the electrical properties of polyvinyl alcohol (PVA) films. PVA films of 4 mm were exposed to a charged (ion/electron) beam for different treatment times (15, 30, and 60 minutes); the beam was produced from a dual beam source using nitrogen gas with the other ion/electron source parameters optimized. The dielectric loss tangent tan δ , electrical conductivity σ , and dielectric constant ɛ ^' } in the frequency range 100 Hz-100 kHz were measured at room temperature. The variation of dielectric constant and loss tangent as a function of frequency was also studied at room temperature. The dielectric constant was found to be strongly dependent on frequency for both ion and electron beam irradiation doses. The real (ɛ ^' }) and imaginary (ɛ ^' ' }) parts of the dielectric constant decreased with frequency for all irradiated and non-irradiated samples. The AC conductivity showed an increase with frequency for all samples under the influence of both ion and electron irradiation for different times. Photoluminescence (PL) spectral changes were also studied. The formation of clusters and defects (which serve as non-radiative centers on the polymer surface) is confirmed by the decrease in the PL intensity.

  2. Ion-irradiation of complex hydrocarbons: implications for small Solar System bodies

    NASA Astrophysics Data System (ADS)

    Moroz, L.; Baratta, G.; Distefano, E.; Strazzulla, G.; Dotto, E.; Barucci, M.; Arnold, G.

    2003-04-01

    Trans-Neptunian Objects (TNOs) and cometary nuclei show remarkable color variations. In the visual and near-infrared spectral regions their colors may range from red to gray or bluish. This probably indicates that surface alteration processes such as space weathering and impact resurfacing plays an essential role in the color diversity of such bodies. In particular, some previous laboratory ion-irradiation experiments demonstrated a transformation of surface colors of ices from gray to red and further to gray. Additional possibility is a transformation of originally red dark refractory organic surface components into a gray carbonized material as a result of ion irradiation. We simulated such an "ageing" effect by an irradiation of a natural dark red organic samples (asphaltite and kerite). The samples were irradiated by 30-60 keV H+, N+ and Ar++ ions and their reflectance spectra were measured before and after irradiation. The results indicate that initially red spectra of organics progressively flatten with increasing ion fluences. The laboratory spectra have been compared with astronomical spectra of TNOs. We demonstrate that an observed variety of TNO’ spectral slopes can be reproduced by our laboratory spectra corresponding to different ion fluences. If we assume that fresh surfaces of some TNOs are red due to their refractory organic components, then their irradiation by ion populations in the Solar System in combination with collisional evolution exposing these fresh surfaces could have produced a variety of colors.

  3. Evolutions of Molecular Oxygen Formation and Sodium Migration in Xe Ion Irradiated Borosilicate Glasses

    SciTech Connect

    Chen, Liang; Zhang, Duofei F.; Lv, Peng; Zhang, Jiandong; Du, Xing; Yuan, Wei; Nan, Shuai; Zhu, Zihua; Wang, Tieshan

    2016-07-23

    The modifications of a commercial borosilicate glass induced by Xe ion irradiation have been studied by Raman spectroscopy and ToF-SIMS depth profiling. A decrease in the average Si–O–Si angle, an increase in the population of three-membered rings and an increase of the glass polymerization are evidenced. The molecular oxygen appears in the irradiated glasses after the irradiation fluence reaches approximately 1015 ions/cm2. The O2 concentration decreaseswith the depth of irradiated glass at the ion fluence of 2 × 1016 ions/cm2. A sodiumdepleted layer at the surface and a depleted zone at around the penetration depth of 5 MeV Xe ions are observed. The thickness of the sodium depleted layer increases with the irradiation fluence. Moreover, comparing with previous results after electron and Ar ion irradiation, it can be concluded that the nuclear energy deposition can partially inhibit the formation of molecular oxygen and increase the threshold value of electron energy deposition for the molecular oxygen formation.

  4. A light-driven sodium ion pump in marine bacteria.

    PubMed

    Inoue, Keiichi; Ono, Hikaru; Abe-Yoshizumi, Rei; Yoshizawa, Susumu; Ito, Hiroyasu; Kogure, Kazuhiro; Kandori, Hideki

    2013-01-01

    Light-driven proton-pumping rhodopsins are widely distributed in many microorganisms. They convert sunlight energy into proton gradients that serve as energy source of the cell. Here we report a new functional class of a microbial rhodopsin, a light-driven sodium ion pump. We discover that the marine flavobacterium Krokinobacter eikastus possesses two rhodopsins, the first, KR1, being a prototypical proton pump, while the second, KR2, pumps sodium ions outward. Rhodopsin KR2 can also pump lithium ions, but converts to a proton pump when presented with potassium chloride or salts of larger cations. These data indicate that KR2 is a compatible sodium ion-proton pump, and spectroscopic analysis showed it binds sodium ions in its extracellular domain. These findings suggest that light-driven sodium pumps may be as important in situ as their proton-pumping counterparts.

  5. Berkeley Accelerator Space Effects (BASE) Light Ion FacilityUpgrade

    SciTech Connect

    Johnson, Michael B.; McMahan, Margaret A.; Gimpel, Thomas L.; Tiffany, William S.

    2006-07-07

    The BASE Light Ion Facility upgrades have been completed. All proton beams are now delivered to Cave 4A. New control software, a larger diameter beam window, and improved quality assurance measures have been added.

  6. NUCFRG3: Light ion improvements to the nuclear fragmentation model

    NASA Astrophysics Data System (ADS)

    Adamczyk, A. M.; Norman, R. B.; Sriprisan, S. I.; Townsend, L. W.; Norbury, J. W.; Blattnig, S. R.; Slaba, T. C.

    2012-06-01

    Light ion improvements to the nuclear fragmentation model, NUCFRG, are reported. Improvements include the replacement of the simple light ion production model with a light ion coalescence model and an improved electromagnetic dissociation (EMD) formalism. Prior versions of the model provide reasonable overall agreement with measured data; however, those versions lack a physics-based description for coalescence and EMD. The version reported herein, NUCFRG3, has improved the theoretical descriptions of these mechanisms and offers additional benefits, such as the capability to calculate EMD cross-sections for single deuteron, triton, helion, and alpha particle emission. NUCFRG3 model evaluation and validation show that the predictive capability has been improved and strengthened by the light ion physics-based changes. Based on increased capability and better theoretical grounding, it is recommended that NUCFRG3 replace its predecessors for space radiation assessments and other applications.

  7. NUCFRG3: Light ion improvements to the nuclear fragmentation model

    NASA Astrophysics Data System (ADS)

    Adamczyk, Anne; Norman, Ryan; Sriprisan, Sirikul; Townsend, Lawrence; Norbury, John; Blattnig, Steve; Slaba, Tony

    2011-10-01

    Light ion improvements to the nuclear fragmentation model NUCFRG are reported. Improvements include the replacement of the simple light ion production model with a light ion coalescence model and an improved electromagnetic dissociation (EMD) formalism. Prior versions of the model provide reasonable overall agreement with measured data; however, those versions lack a physics-based description for coalescence and EMD. The NUCFRG3 model has improved theoretical descriptions of these mechanisms and offers additional benefits. Previous work established the improved EMD formalism to be more accurate than the predecessor. The predictive capability of NUCFRG has been improved and strengthened by the light ion physics-based changes. Based on increased capability and better theoretical grounding of NUCFRG3, it is recommended that it replace NUCFRG2 for space radiation assessments and other applications.

  8. Blue light irradiation-induced oxidative stress in vivo via ROS generation in rat gingival tissue.

    PubMed

    Yoshida, Ayaka; Shiotsu-Ogura, Yukako; Wada-Takahashi, Satoko; Takahashi, Shun-suke; Toyama, Toshizo; Yoshino, Fumihiko

    2015-10-01

    It has been reported that oxidative stress with reactive oxygen species (ROS) generation is induced by blue light irradiation to a living body. Only limited research has been reported in dental field on the dangers of blue light, mostly focusing on cytotoxicity associated with heat injury of dental pulp. We thus performed an in vivo study on oral tissue exposed to blue light. ROS generated upon blue light irradiation of flavin adenine dinucleotide were measured by electron spin resonance spectroscopy. After blue light irradiation, the palatal gingiva of Wistar rats were isolated. Collected samples were subjected to biochemical analysis of lipid peroxidation and glutathione. Singlet oxygen was generated by blue light irradiation, but was significantly quenched in an N-acetyl-L-cysteine (NAC) concentration-dependent manner. Blue light significantly accelerated oxidative stress and increased the oxidized glutathione levels in gingival tissue. These effects were also inhibited by NAC pre-administration. The results suggest that blue light irradiation at clinical levels of tooth bleaching treatment may enhance lipid peroxidation by the induction of oxidative stress and the consumption of a significant amount of intracellular glutathione. In addition, NAC might be an effective supplement for the protection of oral tissues against blue light irradiation-induced oxidative damage. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Enhancement of electric double layer capacitance of carbon nanotubes by gallium ion irradiation

    SciTech Connect

    Rai, Padmnabh; Pandey, Srikrishna; Menemparabath, Minimol; Sug Kim, Young; Nikolaev, Pavel; Arepalli, Sivaram; Lee, Il Ha

    2011-02-15

    Irradiation by 30 keV Ga{sup +} ions was used to create defects in multiwalled carbon nanotubes. Damage to the graphitic structure of the nanotube wall resulting from ion irradiation was observed by a transmission electron microscope which was accompanied by corresponding changes in Raman spectra. It was found that ion irradiation at 2 x 10{sup 13} ions/cm{sup 2} cumulative dose increases the electric double layer capacitance of a multiwalled carbon nanotube electrode by a factor of 2.3, followed by a decrease and saturation at higher (2 x 10{sup 14} and 4 x 10{sup 14} ions/cm{sup 2}) doses. This might be a trade-off between the enhancement caused by the tip opening and lowering of the capacitance due to amorphization of carbon nanotubes.

  10. Micro-Raman spectroscopy characterization of silicon with different structures irradiated with energetic Bi-ions

    NASA Astrophysics Data System (ADS)

    Zhu, Yabin; Yao, Cunfeng; Wang, Ji; Zhu, Huiping; Shen, Tielong; Gao, Xing; Sun, Jianrong; Wei, Kongfang; Wang, Dong; Sheng, Yanbin; Wang, Zhiguang

    2015-12-01

    Researches of irradiation effects on silicon possess not only fundamental interests but also potential application prospects. Comparison studies about structural modification of silicon materials with different structures under identical irradiation conditions can reveal the irradiation mechanisms for amorphous and crystalline phases of silicon. For this purpose, amorphous silicon (a-Si) and nano-crystalline silicon (nc-Si) films as well as mono-crystalline silicon (c-Si) samples were irradiated with 6.0 MeV Bi-ions at room temperature. The ion fluences are 1.0 × 1013, 5.0 × 1013 and 1.0 × 1014 ions/cm2. All samples were analyzed by using a Raman spectrometer. The obtained results show that the crystalline fraction of c-Si and nc-Si decrease with increasing fluence, which indicates that the irradiation induces the amorphization of nc-Si and c-Si samples. In addition, the variation in Raman frequency of crystalline peak after irradiation reveals that the irradiation also results in the increased stress in crystalline phase of c-Si and nc-Si samples. As the fluence increases, the bond angle deviation and the ratio of TA to TO mode of amorphous network of a-Si and nc-Si films initially increase and then decrease by a diminishing degree, while the bond angle deviation and the ratio of TA to TO mode of amorphous network of c-Si samples increase continuously. This gives the dependence of short-range structural order of amorphous network of a-Si, nc-Si and c-Si samples on the ion fluence, which is related with the irradiation induced variation of local free energy. It is considered that the irradiation induced structural modification of silicon samples is mainly attributed to the nuclear energy loss. The irradiation effects of energetic heavy-ions on crystalline and amorphous phases of silicon have been discussed, respectively.

  11. Accumulation of dislocation loops in the α phase of Zr Excel alloy under heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Yu, Hongbing; Yao, Zhongwen; Idrees, Yasir; Zhang, He K.; Kirk, Mark A.; Daymond, Mark R.

    2017-08-01

    In-situ heavy ion irradiations were performed on the high Sn content Zr alloy 'Excel', measuring type dislocation loop accumulation up to irradiation damage doses of 10 dpa at a range of temperatures. The high content of Sn, which diffuses slowly, and the thin foil geometry of the sample provide a unique opportunity to study an extreme case where displacement cascades dominate the loop formation and evolution. The dynamic observation of dislocation loop evolution under irradiation at 200 °C reveals that type dislocation loops can form at very low dose (0.0025 dpa). The size of the dislocation loops increases slightly with irradiation damage dose. The mechanism controlling loop growth in this study is different from that in neutron irradiation; in this study, larger dislocation loops can condense directly from the interaction of displacement cascades and the high concentration of point defects in the matrix. The size of the dislocation loop is dependent on the point defect concentration in the matrix. A negative correlation between the irradiation temperature and the dislocation loop size was observed. A comparison between cascade dominated loop evolution (this study), diffusion dominated loop evolution (electron irradiation) and neutron irradiation suggests that heavy ion irradiation alone may not be enough to accurately reproduce neutron irradiation induced loop structures. An alternative method is proposed in this paper. The effects of Sn on the displacement cascades, defect yield, and the diffusion behavior of point defects are established.

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

    SciTech Connect

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

    2008-01-15

    {gamma}-In{sub 2}Se{sub 3} thin films prepared at different annealing temperatures ranging from 100 to 400 deg. C were irradiated using 90 MeV Si ions with a fluence of 2x10{sup 13} ions/cm{sup 2}. X-ray diffraction analysis proved that there is no considerable variation in structural properties of the films due to the swift heavy ion irradiation. However, photosensitivity and sheet resistance of the samples increased due to irradiation. It was observed that the sample, which had negative photoconductivity, exhibited positive photoconductivity, after irradiation. The negative photoconductivity was due to the combined effect of trapping of photoexcited electrons, at traps 1.42 and 1.26 eV, above the valence band along with destruction of the minority carriers, created during illumination, through recombination. Photoluminescence study revealed that the emission was due to the transition to a recombination center, which was 180 meV above the valence band. Optical absorption study proved that the defects present at 1.42 and 1.26 eV were annealed out by the ion beam irradiation. This allowed photoexcited carriers to reach conduction band, which resulted in positive photoconductivity. Optical absorption study also revealed that the band gap of the material could be increased by ion beam irradiation. The sample prepared at 400 deg. C had a band gap of 2 eV and this increased to 2.8 eV, after irradiation. The increase in optical band gap was attributed to the annihilation of localized defect bands, near the conduction and valence band edges, on irradiation. Thus, by ion beam irradiation, one could enhance photosensitivity as well as the optical band gap of {gamma}-In{sub 2}Se{sub 3}, making the material suitable for applications such as window layer in solar cells.

  13. Carbon Ion Irradiation Effects on Pulsed Laser Deposited Titanium Nitride Thin Films

    NASA Astrophysics Data System (ADS)

    Mahmood, Khaliq; Bashir, Shazia; Akram, Mahreen; Hayat, Asma; Faizan-Ul-Haq; Saadat, Shahzad

    2015-02-01

    Pulse laser deposited thin films of TiN are irradiated by 1 MeV carbon (C+) ions beam for various doses ranging 0.4 to 2.8 × 1014 ions/cm2. Atomic force microscopy (AFM) analysis reveals the formation of hillocks like structures after ion irradiation. X-ray diffraction (XRD) investigations show that the film crystallinity increases for lower doses ranging from 0.4 to 1.2 × 1014 ions/cm2 and decreases for higher doses (2 to 2.8 × 1014 ions/cm2) of ions. No new bands are identified from Raman spectroscopy. However, a noticeable change in microhardness has been observed. The hillock densities as well as hardness are strongly dependent upon ion dose.

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

    SciTech Connect

    Zinkle, S.J.

    1991-01-01

    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.

  15. Magnetic patterning using ion irradiation for highly ordered CoPt alloys with perpendicular anisotropy

    SciTech Connect

    Abes, M.; Venuat, J.; Muller, D.; Carvalho, A.; Schmerber, G.; Beaurepaire, E.; Dinia, A.; Pierron-Bohnes, V.

    2004-12-15

    We used a combination of ion irradiation and e-beam lithography to magnetically pattern an ordered CoPt alloy with strong perpendicular magnetic anisotropy. Ion irradiation disorders the alloy and strongly reduces the magnetic anisotropy. Magnetic force microscopy showed a regular array of 1 {mu}m{sup 2} square dots with perpendicular anisotropy separated by 1 {mu}m large ranges with in-plane anisotropy. This is further confirmed by magnetic measurements, which showed that arrays protected by a 200 nm Pt layer present the same coercive field and the same perpendicular anisotropy as before irradiation. This is promising for applications in magnetic recording technologies.

  16. Characterization of Vacancy Defects in Carbon Ion Irradiated Graphite Using Positrons

    SciTech Connect

    Anto, C. Varghese; Arunkumar, J.; Rajaraman, R.; Nair, K. G. M.; Amarendra, G.

    2011-07-15

    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.

  17. Different effects of light irradiation on the photosynthetic electron transport chain during apple tree leaf dehydration.

    PubMed

    Li, Pengmin; Ma, Fengwang

    2012-06-01

    Effects of light irradiation on the photosynthetic electron transport chain between P680 and P700 in apple tree leaves was probed with chlorophyll a fluorescence transient and 820 nm transmission measurements during dehydration under different light intensities. The results showed that light accelerated the leaf water-loss rate during dehydration. Leaf dehydration lowered the maximum quantum yield of PSII and the far-red light induced maximal transmission change at 820 nm, but increased the relative variable fluorescence intensity at J-step, especially under increasing irradiation conditions. During leaf dehydration, irradiation lowered the relative variable fluorescence intensity at I-step. At the beginning of leaf dehydration, moderate light accelerated the leaf water-loss rate and then lowered the maximal light-trapping efficiency of P₆₈₀. Upon further dehydration under moderate light or dehydration under high light, light accelerated the water-loss rate and also directly decreased the maximal light-trapping efficiency of P680. The more significant decrease in the exchange capacity of plastoquinones at the Q(B) site was mainly attributed to the faster water-loss rate under moderate light than in the dark. Under high light, irradiation also directly lowered the capacity. The reoxidation of PQH₂ in the dehydrated leaves was enhanced by the light irradiation. The rapidly decreased contents of P700 + plastocyanin were mainly attributed to the faster water-loss rate under light conditions in contrast with that in the dark. The different effects of light irradiations on the photosynthetic electron transport chain might be involved in the acclimation of apple tree leaves to dehydration. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  18. Optical damage assessment and recovery investigation of hydrogen-ion and deuterium-ion plasma-irradiated bulk ZnO single crystals

    NASA Astrophysics Data System (ADS)

    Empizo, Melvin John F.; Yamanoi, Kohei; Mori, Kazuyuki; Iwano, Keisuke; Iwasa, Yuki; Minami, Yuki; Arita, Ren; Fukuda, Kazuhito; Takano, Keisuke; Shimizu, Toshihiko; Nakajima, Makoto; Yoshimura, Masashi; Sarukura, Nobuhiko; Norimatsu, Takayoshi; Hangyo, Masanori; Azechi, Hiroshi; Fukuda, Tsuguo; Singidas, Bess G.; Sarmago, Roland V.; Oya, Makoto; Ueda, Yoshio

    2017-05-01

    In realizing zinc oxide (ZnO) scintillator applications, we assess the optical damage and investigate the recovery of hydrogen-ion (H-ion) and deuterium-ion (D-ion) plasma-irradiated bulk ZnO single crystals. Hydrothermal-grown bulk crystals are irradiated with H-ion and D-ion beams with 1 keV energy and ˜ 10 20 m - 2 s - 1 flux. After irradiation, the single crystals exhibit decreased visible transparencies, redshifted ultraviolet (UV) emission peaks, shortened UV emission lifetimes, and suppressed visible emission bands. These changes in the optical transmittances and photoluminescence emissions are attributed to the generation of defects during irradiation and to the interaction of hydrogen with other defects and/or impurities. Although modified by ion irradiation, the optical properties of the ZnO crystals, except for the UV emission lifetimes, recover hours after without any sample treatment and only at room temperature. Compared with the H-ion-irradiated sample, the D-ion-irradiated crystal has a slower recovery which may be related to the ions' masses, energy losses, and absolute diffusivities. Our results nevertheless show that bulk ZnO single crystals exhibit resistance to and recovery from H-ion and D-ion irradiation and can therefore be used as scintillator materials for radiation detectors inside future fusion reactors.

  19. Observations of defect structure evolution in proton and Ni ion irradiated Ni-Cr binary alloys

    NASA Astrophysics Data System (ADS)

    Briggs, Samuel A.; Barr, Christopher M.; Pakarinen, Janne; Mamivand, Mahmood; Hattar, Khalid; Morgan, Dane D.; Taheri, Mitra; Sridharan, Kumar

    2016-10-01

    Two binary Ni-Cr model alloys with 5 wt% Cr and 18 wt% Cr were irradiated using 2 MeV protons at 400 and 500 °C and 20 MeV Ni4+ ions at 500 °C to investigate microstructural evolution as a function of composition, irradiation temperature, and irradiating ion species. Transmission electron microscopy (TEM) was applied to study irradiation-induced void and faulted Frank loops microstructures. Irradiations at 500 °C were shown to generate decreased densities of larger defects, likely due to increased barriers to defect nucleation as compared to 400 °C irradiations. Heavy ion irradiation resulted in a larger density of smaller voids when compared to proton irradiations, indicating in-cascade clustering of point defects. Cluster dynamics simulations were in good agreement with the experimental findings, suggesting that increases in Cr content lead to an increase in interstitial binding energy, leading to higher densities of smaller dislocation loops in the Ni-18Cr alloy as compared to the Ni-5Cr alloy.

  20. A novel way to estimate the nanoindentation hardness of only-irradiated layer and its application to ion irradiated Fe-12Cr alloy

    NASA Astrophysics Data System (ADS)

    Kim, Hoon-Seop; Lee, Dong-Hyun; Seok, Moo-Young; Zhao, Yakai; Kim, Woo-Jin; Kwon, Dongil; Jin, Hyung-Ha; Kwon, Junhyun; Jang, Jae-il

    2017-04-01

    While nanoindentation is a very useful tool to examine the mechanical properties of ion irradiated materials, there are some issues that should be considered in evaluating the properties of irradiated layer. In this study, in order to properly extract the hardness of only-irradiated layer from nanoindentation data, a new procedure is suggested in consideration of the geometry of indentation-induced plastic zone. By applying the procedure to an ion irradiated Fe-12Cr alloy, the reasonable results were obtained, validating its usefulness in the investigation of practical effect of irradiation on the mechanical behavior of future nuclear materials.

  1. Swift heavy ion irradiation induced nanograin formation in CdTe thin films

    NASA Astrophysics Data System (ADS)

    Survase, Smita; Narayan, Himanshu; Sulania, I.; Thakurdesai, Madhavi

    2016-11-01

    Swift Heavy Ion (SHI) irradiation is a unique technique for nanograin formation through grain fragmentation. Contrary to the generally reported SHI irradiation induced grain growth on CdTe thin films, we report fragmentation leading to nanograin formation. Thermally evaporated polycrystalline CdTe thin films were irradiated with 100 MeV 197Au, 107Ag and 58Ni ions beams up to a fluence of 5 × 1012 ions/cm2. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were carried out for surface analysis before and after irradiation. SEM micrographs indicate that the larger grains in the as-deposited films were fragmented into smaller grains due to irradiation. The extent of fragmentation was found to increase with increasing electronic energy loss (Se). AFM pictures also supported the irradiation induced fragmentation. Structural characterization was done using X-ray Diffraction (XRD) technique. The ion induced strain and dislocation density were calculated from the XRD data. Both the strain and dislocation density were found to increase with increasing Se . The observed grain fragmentation is explained on the basis of a combined effect of strain induced disintegration of grains after the Coulomb explosion, and an 'incomplete' re-crystallization of the molten thermal spikes. Moreover, the optical band gap Eg (1.5 eV for as-deposited film), determined from UV-vis spectroscopy, increased with Se, and possibly because of ion induced strain and defect annealing.

  2. Ion irradiation induced defect evolution in Ni and Ni-based FCC equiatomic binary alloys

    SciTech Connect

    Jin, Ke; Zhang, Yanwen; Bei, Hongbin

    2016-01-01

    In order to explore the chemical effects on radiation response of alloys with multi-principal elements, defect evolution under Au ion irradiation was investigated in the elemental Ni, equiatomic NiCo and NiFe alloys. Single crystals were successfully grown in an optical floating zone furnace and their (100) surfaces were irradiated with 3 MeV Au ions at fluences ranging from 1 × 1013 to 5 × 1015 ions cm–2 at room temperature. The irradiation-induced defect evolution was analyzed by using ion channeling technique. Experiment shows that NiFe is more irradiation-resistant than NiCo and pure Ni at low fluences. With continuously increasing the ion fluences, damage level is eventually saturated for all materials but at different dose levels. The saturation level in pure Ni appears at relatively lower irradiation fluence than the alloys, suggesting that damage accumulation slows down in the alloys. Here, under high-fluence irradiations, pure Ni has wider damage ranges than the alloys, indicating that defects in pure Ni have high mobility.

  3. Ion irradiation induced defect evolution in Ni and Ni-based FCC equiatomic binary alloys

    DOE PAGES

    Jin, Ke; Zhang, Yanwen; Bei, Hongbin

    2016-01-01

    In order to explore the chemical effects on radiation response of alloys with multi-principal elements, defect evolution under Au ion irradiation was investigated in the elemental Ni, equiatomic NiCo and NiFe alloys. Single crystals were successfully grown in an optical floating zone furnace and their (100) surfaces were irradiated with 3 MeV Au ions at fluences ranging from 1 × 1013 to 5 × 1015 ions cm–2 at room temperature. The irradiation-induced defect evolution was analyzed by using ion channeling technique. Experiment shows that NiFe is more irradiation-resistant than NiCo and pure Ni at low fluences. With continuously increasing themore » ion fluences, damage level is eventually saturated for all materials but at different dose levels. The saturation level in pure Ni appears at relatively lower irradiation fluence than the alloys, suggesting that damage accumulation slows down in the alloys. Here, under high-fluence irradiations, pure Ni has wider damage ranges than the alloys, indicating that defects in pure Ni have high mobility.« less

  4. Influence of Oxygen ions irradiation on Polyaniline/Single Walled Carbon Nanotubes nanocomposite

    NASA Astrophysics Data System (ADS)

    Patil, Harshada K.; Deshmukh, Megha A.; Gaikwad, Sumedh D.; Bodkhe, Gajanan A.; Asokan, K.; Yasuzawa, Mikito; Koinkar, Pankaj; Shirsat, Mahendara D.

    2017-01-01

    Influence of Oxygen ions (100 MeV) irradiation on Polyaniline (PANI)/Single Walled Carbon Nanotubes (SWNTs) nanocomposite was studied in the present investigation. PANI/SWNTs nanocomposite was synthesized by electrochemical Cyclic Voltammetry technique. Nanocomposite was exposed under SHI irradiation of Oxygen (100 MeV) ions for three different fluences such as 1×1010 ions/cm2, 5×1010 ions/cm2 and 1×1011 ions/cm2. The SHI irradiated PANI/SWNTs nanocomposite was investigated by using morphological (AFM), structural (XRD) and spectroscopy (FTIR) characterization. AFM study exhibits effects of SHI irradiation on morphology of the nanocomposite and root mean square roughness of the nanocomposite is observed to be decreased as fluence was increased. The FTIR absorption spectrum exhibits formation of new functional sites with the increase in intensity of absorption peaks, due to SHI irradiation. X-Ray Diffraction studies show a gradual decrease in the crystalline nature of the nanocomposite upon irradiation.

  5. Ion irradiation induced defect evolution in Ni and Ni-based FCC equiatomic binary alloys

    NASA Astrophysics Data System (ADS)

    Jin, K.; Bei, H.; Zhang, Y.

    2016-04-01

    In order to explore the chemical effects on radiation response of alloys with multi-principal elements, defect evolution under Au ion irradiation was investigated in the elemental Ni, equiatomic NiCo and NiFe alloys. Single crystals were successfully grown in an optical floating zone furnace and their (100) surfaces were irradiated with 3 MeV Au ions at fluences ranging from 1 × 1013 to 5 × 1015 ions cm-2 at room temperature. The irradiation-induced defect evolution was analyzed by using ion channeling technique. Experiment shows that NiFe is more irradiation-resistant than NiCo and pure Ni at low fluences. With continuously increasing the ion fluences, damage level is eventually saturated for all materials but at different dose levels. The saturation level in pure Ni appears at relatively lower irradiation fluence than the alloys, suggesting that damage accumulation slows down in the alloys. Under high-fluence irradiations, pure Ni has wider damage ranges than the alloys, indicating that defects in pure Ni have high mobility.

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

    SciTech Connect

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

    1995-12-31

    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.

  7. Production of a thermal stress resistant mutant Euglena gracilis strain using Fe-ion beam irradiation.

    PubMed

    Yamada, Koji; Kazama, Yusuke; Mitra, Sharbanee; Marukawa, Yuka; Arashida, Ryo; Abe, Tomoko; Ishikawa, Takahiro; Suzuki, Kengo

    2016-08-01

    Euglena gracilis is a common phytoplankton species, which also has motile flagellate characteristics. Recent research and development has enabled the industrial use of E. gracilis and selective breeding of this species is expected to further expand its application. However, the production of E. gracilis nuclear mutants is difficult because of the robustness of its genome. To establish an efficient mutation induction procedure for E. gracilis, we employed Fe-ion beam irradiation in the RIKEN RI beam factory. A decrease in the survival rate was observed with the increase in irradiation dose, and the upper limit used for E. gracilis selective breeding was around 50 Gy. For a practical trial of Fe-ion irradiation, we conducted a screening to isolate high-temperature-tolerant mutants. The screening yielded mutants that proliferated faster than the wild-type strain at 32 °C. Our results demonstrate the effectiveness of heavy-ion irradiation on E. gracilis selective breeding.

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

    PubMed

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

    2013-04-15

    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. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Tailoring nonlinear optical properties of Bi2Se3 through ion irradiation

    NASA Astrophysics Data System (ADS)

    Tan, Yang; Guo, Zhinan; Shang, Zhen; Liu, Fang; Böttger, Roman; Zhou, Shengqiang; Shao, Jundong; Yu, Xuefeng; Zhang, Han; Chen, Feng

    2016-02-01

    The nonlinear optical property of topological insulator bismuth selenide (Bi2Se3) is found to be well-tailored through ion irradiation by intentionally introducing defects. The increase of the optical modulation depth sensitively depends on the careful selection of the irradiation condition. By implementing the ion irradiated Bi2Se3 film as an optical saturable absorber device for the Q-switched wave-guide laser, an enhanced laser performance has been obtained including narrower pulse duration and higher peak power. Our work provides a new approach of tailoring the nonlinear optical properties of materials through ion irradiation, a well-developed chip-technology, which could find wider applicability to other layered two-dimensional materials beyond topological insulators, such as graphene, MoS2, black phosphours etc.

  10. Tailoring nonlinear optical properties of Bi2Se3 through ion irradiation

    PubMed Central

    Tan, Yang; Guo, Zhinan; Shang, Zhen; Liu, Fang; Böttger, Roman; Zhou, Shengqiang; Shao, Jundong; Yu, Xuefeng; Zhang, Han; Chen, Feng

    2016-01-01

    The nonlinear optical property of topological insulator bismuth selenide (Bi2Se3) is found to be well-tailored through ion irradiation by intentionally introducing defects. The increase of the optical modulation depth sensitively depends on the careful selection of the irradiation condition. By implementing the ion irradiated Bi2Se3 film as an optical saturable absorber device for the Q-switched wave-guide laser, an enhanced laser performance has been obtained including narrower pulse duration and higher peak power. Our work provides a new approach of tailoring the nonlinear optical properties of materials through ion irradiation, a well-developed chip-technology, which could find wider applicability to other layered two-dimensional materials beyond topological insulators, such as graphene, MoS2, black phosphours etc. PMID:26888223

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

    SciTech Connect

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

    2010-10-04

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

  12. Ion microbeam irradiation for radiobiology and radical chemistry: status and prospect

    NASA Astrophysics Data System (ADS)

    Khodja, H.

    2011-01-01

    Ion microbeams are commonly used to study local irradiation effects in living cells, as it has been established that ion beam irradiations can lead to deleterious changes in cells that are not struck directly by the microbeam. Such changes, which take place over distances long compared to the size of the irradiation spot and for times long compared to the time of irradiation, are collectively termed radiation-induced bystander effect or RIBE. Free-radical chemistry is frequently invoked to explain the RIBE but no unified model is available at present. Ion microbeams when coupled with advanced methods for observing free radicals are the tools of choice for investigating the chemistry and biological processes governing RIBE.

  13. Amorphization resistance of nano-engineered SiC under heavy ion irradiation

    SciTech Connect

    Imada, Kenta; Ishimaru, Manabu; Xue, Haizhou; Zhang, Yanwen; Shannon, Steven C.; Weber, William J.

    2016-06-19

    Silicon carbide (SiC) with a high-density of planar defects (hereafter, ‘nano-engineered SiC’) and epitaxially-grown single-crystalline 3C-SiC were simultaneously irradiated with Au ions at room temperature, in order to compare their relative resistance to radiation-induced amorphization. Furthermore, it was found that the local threshold dose for amorphization is comparable for both samples under 2 MeV Au ion irradiation; whereas, nano-engineered SiC exhibits slightly greater radiation tolerance than single crystalline SiC under 10 MeV Au irradiation. Under 10 MeV Au ion irradiation, the dose for amorphization increased by about a factor of two in both nano-engineered and single crystal SiC due to the local increase in electronic energy loss that enhanced dynamic recovery.

  14. Ion irradiation effects on conduction in single-wall carbon nanotube networks

    NASA Astrophysics Data System (ADS)

    Skákalová, V.; Kaiser, A. B.; Osváth, Z.; Vértesy, G.; Biró, L. P.; Roth, S.

    2008-03-01

    We have measured how irradiation by Ar+ and N+ ions modifies electronic conduction in single-wall carbon nanotube (SWNT) networks, finding dramatically different effects for different thicknesses. For very thin transparent networks, ion irradiation increases localization of charge carriers and reduces the variable-range hopping conductivity, especially at low temperatures. However, for thick networks (SWNT paper) showing metallic conductivity, we find a relatively sharp peak in conductivity as a function of irradiation dose. Our investigation of this peak reveals the important role of thermal annealing extending beyond the range of the irradiating ions, and shows the dependence on the morphology of the samples. We propose a simple model that accounts for the temperature-dependent conductivity.

  15. Amorphization resistance of nano-engineered SiC under heavy ion irradiation

    SciTech Connect

    Imada, Kenta; Ishimaru, Manabu; Xue, Haizhou; Zhang, Yanwen; Shannon, Steven C.; Weber, William J.

    2016-06-19

    Silicon carbide (SiC) with a high-density of planar defects (hereafter, ‘nano-engineered SiC’) and epitaxially-grown single-crystalline 3C-SiC were simultaneously irradiated with Au ions at room temperature, in order to compare their relative resistance to radiation-induced amorphization. Furthermore, it was found that the local threshold dose for amorphization is comparable for both samples under 2 MeV Au ion irradiation; whereas, nano-engineered SiC exhibits slightly greater radiation tolerance than single crystalline SiC under 10 MeV Au irradiation. Under 10 MeV Au ion irradiation, the dose for amorphization increased by about a factor of two in both nano-engineered and single crystal SiC due to the local increase in electronic energy loss that enhanced dynamic recovery.

  16. Amorphization resistance of nano-engineered SiC under heavy ion irradiation

    DOE PAGES

    Imada, Kenta; Ishimaru, Manabu; Xue, Haizhou; ...

    2016-06-19

    Silicon carbide (SiC) with a high-density of planar defects (hereafter, ‘nano-engineered SiC’) and epitaxially-grown single-crystalline 3C-SiC were simultaneously irradiated with Au ions at room temperature, in order to compare their relative resistance to radiation-induced amorphization. Furthermore, it was found that the local threshold dose for amorphization is comparable for both samples under 2 MeV Au ion irradiation; whereas, nano-engineered SiC exhibits slightly greater radiation tolerance than single crystalline SiC under 10 MeV Au irradiation. Under 10 MeV Au ion irradiation, the dose for amorphization increased by about a factor of two in both nano-engineered and single crystal SiC due tomore » the local increase in electronic energy loss that enhanced dynamic recovery.« less

  17. Tuning the conductivity of vanadium dioxide films on silicon by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Hofsäss, H.; Ehrhardt, P.; Gehrke, H.-G.; Brötzmann, M.; Vetter, U.; Zhang, K.; Krauser, J.; Trautmann, C.; Ko, C.; Ramanathan, S.

    2011-09-01

    We demonstrate the generation of a persistent conductivity increase in vanadium dioxide thin films grown on single crystal silicon by irradiation with 1 GeV 238U swift heavy ions at room temperature. VO2 undergoes a temperature driven metal-insulator-transition (MIT) at 67 °C. After room temperature ion irradiation with high electronic energy loss of 50 keV/nm the conductivity of the films below the transition temperature is strongly increased proportional to the ion fluence of 5.109 U/cm2 and 1.1010 U/cm2. At high temperatures the conductivity decreases slightly. The ion irradiation slightly reduces the MIT temperature. This observed conductivity change is persistent and remains after heating the samples above the transition temperature and subsequent cooling. Low temperature measurements down to 15 K show no further MIT below room temperature. Although the conductivity increase after irradiation at such low fluences is due to single ion track effects, atomic force microscopy (AFM) measurements do not show surface hillocks, which are characteristic for ion tracks in other materials. Conductive AFM gives no evidence for conducting ion tracks but rather suggests the existence of conducting regions around poorly conducting ion tracks, possible due to stress generation. Another explanation of the persistent conductivity change could be the ion-induced modification of a high resistivity interface layer formed during film growth between the vanadium dioxide film and the n-Silicon substrate. The swift heavy ions may generate conducting filaments through this layer, thus increasing the effective contact area. Swift heavy ion irradiation can thus be used to tune the conductivity of VO2 films on silicon substrates.

  18. Vibrational Spectroscopy in Ion-Irradiated Carbon-Based Thin Films

    NASA Astrophysics Data System (ADS)

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

    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.

  19. Effective implantation of light emitting centers by plasma immersion ion implantation and focused ion beam methods into nanosized diamond

    NASA Astrophysics Data System (ADS)

    Himics, L.; Tóth, S.; Veres, M.; Tóth, A.; Koós, M.

    2015-02-01

    Two different implantation techniques, plasma immersion ion implantation and focused ion beam, were used to introduce nitrogen ions into detonation nanodiamond crystals with the aim to create nitrogen-vacancy related optically active centers of light emission in near UV region. Previously samples were subjected to a defect creation process by helium irradiation in both cases. Heat treatments at different temperatures (750 °C, 450 °C) were applied in order to initiate the formation of nitrogen-vacancy related complex centers and to decrease the sp2 carbon content formed under different treatments. As a result, a relatively narrow and intensive emission band with fine structure at 2.98, 2.83 and 2.71 eV photon energies was observed in the light emission spectrum. It was assigned to the N3 complex defect center. The formation of this defect center can be expected by taking into account the relatively high dose of implanted nitrogen ions and the overlapped depth distribution of vacancies and nitrogen. The calculated depth profiles distribution for both implanted nitrogen and helium by SRIM simulation support this expectation.

  20. Generation of superparamagnetism in metallic α-iron by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Kuzmann, E.; Stichleutner, S.; Homonnay, Z.; Havancsák, K.; Chisholm, C. U.; El-Sharif, M.; Skuratov, V. A.; Nakanishi, A.; Nomura, K.

    2016-10-01

    57Fe conversion electron Mössbauer spectroscopy was used to study the effect of swift heavy ion irradiation on electrochemically deposited metallic pure α-iron. We succeeded in preparing superparamagnetic iron by irradiating the electrochemically prepared thin α-iron films using 247 MeV Kr ions with a fluence of 1×1013 ion cm-2 which converted 50% of crystalline α-iron into amorphous and superparamagnetic phases, the latter being >20%. The results are discussed in terms of the thermal spike model for the formation of the amorphous phase which could be essential for the formation of superparamagnetic iron.

  1. Strain-dependent Damage in Mouse Lung After Carbon Ion Irradiation

    SciTech Connect

    Moritake, Takashi; Fujita, Hidetoshi; Yanagisawa, Mitsuru; Nakawatari, Miyako; Imadome, Kaori; Nakamura, Etsuko; Iwakawa, Mayumi; Imai, Takashi

    2012-09-01

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

  2. Enhancement of SPHK1 in vitro by carbon ion irradiation in oral squamous cell carcinoma

    SciTech Connect

    Higo, Morihiro; Uzawa, Katsuhiro . E-mail: uzawak@faculty.chiba-u.jp; Kawata, Tetsuya; Kato, Yoshikuni; Kouzu, Yukinao; Yamamoto, Nobuharu; Shibahara, Takahiko; Mizoe, Jun-etsu; Ito, Hisao; Tsujii, Hirohiko; Tanzawa, Hideki

    2006-07-01

    Purpose The purpose of this study was to assess the gene expression changes in oral squamous cell carcinoma (OSCC) cells after carbon ion irradiation. Methods and Materials Three OSCC cell lines (HSC2, Ca9-22, and HSC3) were irradiated with accelerated carbon ion beams or X-rays using three different doses. The cellular sensitivities were determined by clonogenic survival assay. To identify genes the expression of which is influenced by carbon ion irradiation in a dose-dependent manner, we performed Affymetrix GeneChip analysis with HG-U133 plus 2.0 arrays containing 54,675 probe sets. The identified genes were analyzed using the Ingenuity Pathway Analysis Tool to investigate the functional network and gene ontology. Changes in mRNA expression in the genes were assessed by real-time reverse transcriptase-polymerase chain reaction. Results We identified 98 genes with expression levels that were altered significantly at least twofold in each of the three carbon-irradiated OSCC cell lines at all dose points compared with nonirradiated control cells. Among these, SPHK1, the expression of which was significantly upregulated by carbon ion irradiation, was modulated little by X-rays. The function of SPHK1 related to cellular growth and proliferation had the highest p value (p = 9.25e-7 to 2.19e-2). Real-time reverse transcriptase-polymerase chain reaction analysis showed significantly elevated SPHK1 expression levels after carbon ion irradiation (p < 0.05), consistent with microarray data. Clonogenic survival assay indicated that carbon ion irradiation could induce cell death in Ca9-22 cells more effectively than X-rays. Conclusions Our findings suggest that SPHK1 helps to elucidate the molecular mechanisms and processes underlying the biologic response to carbon ion beams in OSCC.

  3. Irradiation for quarantine control of the invasive light brown apple moth, Epiphyas

    USDA-ARS?s Scientific Manuscript database

    The effects of irradiation on egg, larval, and pupal development, and adult reproduction in light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), were examined. Eggs, neonates, early instars, late instars, early pupae and late pupae were irradiated at target doses of 60, ...

  4. Ion irradiation of graphene on Ir(111): From trapping to blistering

    NASA Astrophysics Data System (ADS)

    Herbig, Charlotte; Åhlgren, E. Harriet; Valerius, Philipp; Schröder, Ulrike A.; Martínez-Galera, Antonio J.; Arman, Mohammad A.; Kotakoski, Jani; Knudsen, Jan; Krasheninnikov, Arkady V.; Michely, Thomas

    Graphene grown epitaxially on Ir(111) is irradiated with low energy noble gas ions and the processes induced by atomic collision and subsequent annealing are analyzed using scanning tunneling microscopy, low energy electron diffraction, X-ray photoelectron diffraction and thermal desorption spectroscopy. Upon room temperature ion irradiation graphene amorphizes and recovers its crystalline structure during annealing. The energetic noble gas projectiles are trapped with surprisingly high efficiency under the graphene cover up to extremely high temperatures beyond 1300K. The energy, angle, and ion species dependence of trapping are quantified. At elevated temperatures the trapped gas forms well developed and highly pressurized blisters under the graphene cover. We use molecular dynamics simulations and ab initio calculations to elucidate the trapping mechanism and its thermal robustness. Similar trapping and blistering are observed after ion irradiation of a single layer of hexagonal boron nitride on Ir(111) and we speculate on the generality of the observed phenomena.

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

    SciTech Connect

    Jaafar, M.; Sanz, R.; McCord, J.; Jensen, J.; Schaefer, R.; Vazquez, M.; Asenjo, A.

    2011-03-01

    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.

  6. Magnetic states controlled by energetic ion irradiation in FeRh thin films

    SciTech Connect

    Fujita, Nao.; Kosugi, S.; Matsui, T.; Iwase, A.; Saitoh, Y.; Kaneta, Y.; Kume, K.; Batchuluun, T.; Ishikawa, N.

    2010-05-15

    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.

  7. Ion irradiation of carbonaceous chondrites as a simulation of space weathering on C-complex asteroids

    NASA Astrophysics Data System (ADS)

    Lantz, C.; Brunetto, R.; Barucci, M. A.; Bachelet, C.; Baklouti, D.; Bourçois, J.; Dartois, E.; Duprat, J.; Duret, P.; Engrand, C.; Godard, M.; Ledu, D.; Mivumbi, O.; Fornasier, S.

    2015-10-01

    We are investigating the effects of space weathering on primitive asteroids using ion irradiation on their meteoritic analogs. To do so, we exposed several carbonaceous chondrites (CV Allende, COs Lancé and Frontier Mountain 95002, CM Mighei, CI Alais, and ungrouped Tagish Lake) to 40 keV He+ ions as a simulation of solar wind irradiation using fluences up to 6.1016 ions/cm2 (implantation platform IRMA at CSNSM Orsay). As a test for our new experimental setup, we also studied samples of olivine and diopside. We confirm the reddening and darkening trends on S-type objects, but carbonaceous chondrites present a continuum of behaviors after ion irradiation as a function of the initial albedo and carbon content: from red to blue and from dark to bright.

  8. Effect of ion irradiation on nanoscale TiS2 systems with suppressed Titania phase

    NASA Astrophysics Data System (ADS)

    Hazarika, Saurabh J.; Mohanta, Dambarudhar; Tripathi, A.; Kanjilal, D.

    2016-10-01

    Titanium disulfide (TiS2), being an important of the transition metal dichalcogenide, (TMDC) family, has drawn numerous interest owing to exhibition of tunable band gap as well as high carrier mobility. In this work, we highlight preparation of TiS2 nanopowder with minimal TiO2 content and also demonstrate modified properties upon swift heavy ion irradiation on TiS2 nanoparticles dispersed PVA films. Different properties of the irradiated samples have been characterized through diffraction, microscopic and spectroscopic techniques. As a result of irradiation, due to agglomeration of particles, the grain size is found to increase. We could also observe a red shift after irradiation with increasing fluence, leading to easy flow of electron from valence to conduction band, which shows that conduction of electrons is more in case of irradiated films compared to the pristine one and thus there may be a possibility of using the irradiated samples in various optoelectronic devices.

  9. Generation of light-induced electrical potential from ion exchange membranes containing 4,4{prime}-bipyridine moiety

    SciTech Connect

    Sata, Toshikatsu

    1996-07-15

    Ion exchange membranes, which are some of the most advanced separation membranes, are widely used in industry, i.e., in electrodialysis processes, diffusion dialysis processes, as separators for electrolysis, solid polyelectrolytes for fuel cells, etc. Generation of photovoltage and photocurrent from ion exchange membranes containing a viologen moiety was examined, cation exchange membranes ion-exchanged with methyl viologen and anion exchange membranes to which a viologen moiety was bonded. After the membrane, swelled with ethylene glycol, had been clamped between two ITO electrodes and sealed, it was irradiated with a xenon lamp. In the case of the cation exchange membranes ion-exchanged with methyl viologen, 155.3 mV of photo-voltage was observed immediately after photoirradiation, and the voltage decreased and attained almost a constant value. The photovoltage of anion exchange membranes with the viologen moiety increased very slowly (maximum 81 mV, 405 nA; load resistance 200 K{Omega}) after beginning the irradiation. However, when the light was irradiated again on the membrane after interruption of the irradiation, almost the same photovoltage was generated immediately after the irradiation. Though the anion exchange membrane showed absorbance only at 320 nm in the UV-VIS spectrum, wavelengths between 300 and 400 nm were active to reduce the viologen moiety of the membrane. This might be due to a polymer effect. On the other hand, the electrical resistance between the ITO electrodes decreased upon photoirradiation because of radical formation. In order to accelerate generation of the voltage, an oxidative agent (ferric ions) or a reductive agent (triethanolamine) was added to the system. The photovoltage was generated immediately after irradiation in both cases. Ferric ions act as an electron acceptor and triethanolamine forms cation radicals in the membrane before the irradiation.

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

    SciTech Connect

    Schwartz, K.; Neumann, R.; Trautmann, C.; Volkov, A. E.; Sorokin, M. V.

    2010-10-01

    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.

  11. Time of flight-secondary ion mass spectrometry analysis of protein adsorption on a polyvinylidene difluoride surface modified by ion irradiation.

    PubMed

    Okuji, Shigeto; Kitazawa, Hideaki; Takeda, Yoshihiko

    2016-12-01

    We investigated the effects of nanoscopic surface modification of polyvinylidene difluoride (PVDF) and low-density polyethylene (LDPE) by plasma-based ion implantation on protein adsorption with time of flight-secondary ion mass spectrometry (ToF-SIMS) analysis. The chemical composition of the LDPE and PVDF surfaces was changed by ion irradiation. In particular, irradiation substantially decreased the number of CH and CF bonds on the PVDF surface, but only slightly decreased that of CH bonds for LDPE. These decreases may reflect a higher hydrogen recombination rate of the LDPE than the PVDF surface. An increase in oxygen was observed on both the LDPE and PVDF surfaces following ion irradiation, but was saturated after irradiation of 1×10(15)cm(-2) on the PVDF surface. The hydrophilicity of the ion-irradiated LDPE surface was promoted with an increase of the total ion fluence. Ion irradiation also changed the surface properties of PVDF to become more hydrophilic, but the variation did not correlate with the total ion fluence presumably due to the presence of fluorine atoms and the saturation of oxidation. Both bovine serum albumin (BSA) and collagen adsorption were suppressed on the LDPE surface by ion irradiation, which may have resulted from a decrease of the hydrophobic interaction. By contrast, ion irradiation increased protein adsorption on the PVDF surface, and BSA was adsorbed more than collagen, whereas there was no difference in the adsorption between BSA and collagen on the ion-irradiated LDPE surface. Moreover, the adsorption of BSA decreased on the oxygen- and fluorine-rich PVDF surface. These results indicate that the nanoscopic composition changes on the PVDF surface affect the adsorption behavior of BSA. Specifically, ferroelectric property on the PVDF surface was changed by ion irradiation and the nanoscopic change in polarity presumably affected the protein adsorption. Our findings suggest that selective adsorption control of protein can be

  12. Microdosimetric Monte-Carlo Simulations and Measurements of Heavy Ion Irradiation of a TEPC

    NASA Astrophysics Data System (ADS)

    Rollet, S.; Beck, P.; Bock, F.; Ferrari, A.; Latocha, M.; Uchihori, Y.; Wind, M.

    Microdosimetric methods are well suited for systematic study and quantification of the absorbed energy spatial and temporal distribution in irradiated matter A standard instrument used to measure the energy dissipated in microscopic sites by individual ionizing events is the Tissue Equivalent Proportional Counter TEPC The main focus of this work is to examine interactions of heavy ions with tissue using both experimental and numerical methods Measurements with a TEPC instrument were carried out recently in heavy ion radiation fields at the Heavy Ion Medical Accelerator HIMAC facility in Chiba which belongs to the National Institute of Radiological Sciences NIRS in Japan The instrument has been exposed to two kinds of heavy ions under different irradiation geometries and beam parameters The heavy ions used were Oxygen with energy of 400 MeV u and Iron of 300 MeV u For the simulation of the irradiation experiments two Monte Carlo codes are used namely FLUKA and GEANT4 Both codes are widely used for basic research and applications in radiation protection and dosimetry radiobiology radiotherapy and space Besides scoring average quantities both Monte Carlo codes have the capability to score energy deposition on an event by event basis Thus together with the total energy deposition a simulation of microdosimetric spectra is possible The comparison of measured and simulated lineal energy distribution show a satisfactory agreement both for irradiation with Oxygen ions of 400 MeV u and for Iron ions of 300 MeV u We will discuss in detail the

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

    NASA Astrophysics Data System (ADS)

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

    2006-10-01

    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.

  14. Defect induced modification of structural, topographical and magnetic properties of zinc ferrite thin films by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Raghavan, Lisha; Joy, P. A.; Vijaykumar, B. Varma; Ramanujan, R. V.; Anantharaman, M. R.

    2017-04-01

    Swift heavy ion irradiation provides unique ways to modify physical and chemical properties of materials. In ferrites, the magnetic properties can change significantly as a result of swift heavy ion irradiation. Zinc ferrite is an antiferromagnet with a Neel temperature of 10 K and exhibits anomalous magnetic properties in the nano regime. Ion irradiation can cause amorphisation of zinc ferrite thin films; thus the role of crystallinity on magnetic properties can be examined. The influence of surface topography in these thin films can also be studied. Zinc ferrite thin films, of thickness 320 nm, prepared by RF sputtering were irradiated with 100 MeV Ag ions. Structural characterization showed amorphisation and subsequent reduction in particle size. The change in magnetic properties due to irradiation was correlated with structural and topographical effects of ion irradiation. A rough estimation of ion track radius is done from the magnetic studies.

  15. Buried amorphous layers by electronic excitation in ion-beam irradiated lithium niobate: Structure and kinetics

    SciTech Connect

    Olivares, J.; Garcia-Navarro, A.; Garcia, G.; Agullo-Lopez, F.; Agullo-Rueda, F.; Garcia-Cabanes, A.; Carrascosa, M.

    2007-02-01

    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.

  16. A mechanistic model for depth-dependent hardness of ion irradiated metals

    NASA Astrophysics Data System (ADS)

    Xiao, Xiazi; Chen, Qianying; Yang, Hui; Duan, Huiling; Qu, Jianmin

    2017-03-01

    A mechanistic model was developed for modeling the depth-dependent hardness in ion irradiated metallic materials. The model is capable of capturing the indentation size effect, ion irradiation induced damage gradient effect, and effect of unirradiated region acting as a soft substrate. A procedure was developed and described in detail to parametrize the model based on experimentally obtained hardness vs. indentation depth curves. Very good agreement was observed between our model predictions and experimental data of several different stainless steels subjected to various ion irradiation conditions. In addition, two hardening mechanisms are revealed in the new model. One is the well-known indentation size effect arising from the creation of geometrically necessary dislocations as the indenter pierces into the materials. The other is the irradiation hardening due to the presence of irradiation-induced defects. As a function of indentation depth h, the hardening due to indentation size effect is described by hbar∗ / h , while the hardening due to irradiation first follows a power law form Phn , then changes to Z / h - Q /h3 , where hbar∗ , P, n, Z and Q > 0 are constants. This transition occurs at the indentation depth when the plastic zone reaches the end of the irradiated layer.

  17. Control of cell behavior on PTFE surface using ion beam irradiation

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

    A polytetrafluoroethylene (PTFE) surface is smooth and biologically inert, so that cells cannot attach to it. Ion beam irradiation of the PTFE surface forms micropores and a melted layer, and the surface is finally covered with a large number of small protrusions. Recently, we found that cells could adhere to this irradiated PTFE surface and spread over the surface. Because of their peculiar attachment behavior, these surfaces can be used as biological tools. However, the factors regulating cell adhesion are still unclear, although some new functional groups formed by irradiation seem to contribute to this adhesion. To control cell behavior on PTFE surfaces, we must determine the effects of the outermost irradiated surface on cell adhesion. In this study, we removed the thin melted surface layer by postirradiation annealing and investigated cell behavior on the surface. On the surface irradiated with 3 × 1016 ions/cm2, cells spread only on the remaining parts of the melted layer. From these results, it is clear that the melted layer had a capacity for cell attachment. When the surface covered with protrusions was irradiated with a fluence of 1 × 1017 ions/cm2, the distribution of cells changed after the annealing process from 'sheet shaped' into multicellular aggregates with diameters of around 50 μm. These results indicate that we can control cell behavior on PTFE surfaces covered with protrusions using irradiation and subsequent annealing. Multicellular spheroids can be fabricated for tissue engineering using this surface.

  18. Physical and biological properties of the ion beam irradiated PMMA-based composite films

    NASA Astrophysics Data System (ADS)

    Shanthini, G. M.; Martin, Catherine Ann; Sakthivel, N.; Veerla, Sarath Chandra; Elayaraja, K.; Lakshmi, B. S.; Asokan, K.; Kanjilal, D.; Kalkura, S. Narayana

    2015-02-01

    Polymethyl methacrylate (PMMA) and PMMA-hydroxyapatite (PMMA-HAp) composite films, prepared by the solvent evaporation method were irradiated with 100 MeV Si7+ ions. Crystallographic, morphological and the functional groups of the pristine and irradiated samples were studied using glancing incident X-ray diffraction (GIXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) respectively. SEM reveals the creation of pores, along with an increase in porosity and cluster size on irradiation. Decrease in crystalline nature and crystallite size with an increase in ion fluence was observed from GIXRD patterns. The surface roughness and the wettability of the material were also enhanced, which could favour the cell-material interaction. The irradiated samples adsorbed significantly greater amount of proteins than pristine. Also, irradiation does not produce any toxic byproducts or leachants, and maintains the viability of 3T3 cells. The response of the irradiated samples towards biomedical applications was demonstrated by the improved antimicrobial activity, haemocompatibility and cytocompatibility. Swift heavy ion irradiation (SHI) could be an effective tool to modify and engineer the surface properties of the polymers to enhance the biocompatibility.

  19. Ion-irradiation-induced microstructural modifications in ferritic/martensitic steel T91

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Miao, Yinbin; Li, Meimei; Kirk, Marquis A.; Maloy, Stuart A.; Stubbins, James F.

    2017-07-01

    In this paper, in situ transmission electron microscopy investigations were carried out to study the microstructural evolution of ferritic/martensitic steel T91 under 1 MeV Krypton ion irradiation up to 4.2 × 1015 ions/cm2 at 573 K, 673 K, and 773 K. At 573 K, grown-in defects are strongly modified by black-dot loops, and dislocation networks together with black-dot loops were observed after irradiation. At 673 K and 773 K, grown-in defects are only partially modified by dislocation loops; isolated loops and dislocation segments were commonly found after irradiation. Post irradiation examination indicates that at 4.2 × 1015 ions/cm2, about 51% of the loops were a0 / 2 < 111 > type for the 673 K irradiation, and the dominant loop type was a0 < 100 > for the 773 K irradiation. Finally, a dispersed barrier hardening model was employed to estimate the change in yield strength, and the calculated ion data were found to follow the similar trend as the existing neutron data with an offset of 100-150 MPa.

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

    PubMed

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

    2012-08-01

    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.

  1. Damages in ceramics for nuclear waste transmutation by irradiation with swift heavy ions

    NASA Astrophysics Data System (ADS)

    Beauvy, Michel; Dalmasso, Chrystelle; Thiriet-Dodane, Catherine; Simeone, David; Gosset, Dominique

    2006-01-01

    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.

  2. Simple light guide for measuring irradiance in an aqueous oxygen electrode chamber.

    PubMed

    Vogtschaller, Jeff; Wise, Robert

    2004-01-01

    The light-dependent reactions of photosynthesis are often measured with Clark-type oxygen electrodes yet the irradiance level inside aqueous oxygen electrode reaction vessels is seldom reported due to the difficulty of measuring light inside a small volume chamber. We describe a simple light guide terminating in a 90 degrees prism that can be inserted into a reaction vessel. Incoming irradiation is directed to a commercially available quantum sensor positioned at the other end of the light guide. Both materials for and construction of the device are inexpensive.

  3. Effects of Ion Irradiation on Seedlings Growth Monitored by Ultraweak Delayed Luminescence.

    PubMed

    Grasso, Rosaria; Abe, Tomoko; Cirrone, Giuseppe A P; Cuttone, Giacomo; Gulino, Marisa; Musumeci, Francesco; Romano, Francesco; Ryuto, Hiromichi; Scordino, Agata

    2016-01-01

    The optical technique based on the measurement of delayed luminescence emitted from the biological samples has demonstrated its ability to provide valid and predictive information on the functional status of various biological systems. We want to extend this technique to study the effect of ionizing radiation on biological systems. In particular we are interested in the action of ion beams, used for therapeutic purposes or to increase the biological diversity. In general, the assessment of the damage that radiation produces both in the target objects and in the surrounding tissues, requires considerable time because is based on biochemical analysis or on the examination of the evolution of the irradiated systems. The delayed luminescence technique could help to simplify this investigation. We have so started our studies performing irradiations of some relatively simple vegetable models. In this paper we report results obtained from mung bean (Vigna radiata) seeds submitted to a 12C ion beam at the energy of 62 MeV/nucleon. The dry seeds were irradiated at doses from 50 to 7000 Gy. The photoinduced delayed luminescence of each seed before and after ion irradiation was measured. The growth of seedlings after irradiation was compared with that of untreated seeds. A growth reduction on increasing the dose was registered. The results show strong correlations between the ion irradiation dose, seeds growth and delayed luminescence intensity. In particular, the delayed luminescence intensity is correlated by a logistic function to the seedlings elongation and, after performing a suitable measurement campaign based on blind tests, it could become a tool able to predict the growth of seeds after ion irradiation. Moreover these results demonstrate that measurements of delayed luminescence could be used as a fast and non-invasive technique to check the effects of ion beams on relatively simple biological systems.

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

    PubMed Central

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

    2013-01-01

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

  5. Effects of Ion Irradiation on Seedlings Growth Monitored by Ultraweak Delayed Luminescence

    PubMed Central

    Abe, Tomoko; Cirrone, Giuseppe A. P.; Cuttone, Giacomo; Gulino, Marisa; Musumeci, Francesco; Romano, Francesco; Ryuto, Hiromichi; Scordino, Agata

    2016-01-01

    The optical technique based on the measurement of delayed luminescence emitted from the biological samples has demonstrated its ability to provide valid and predictive information on the functional status of various biological systems. We want to extend this technique to study the effect of ionizing radiation on biological systems. In particular we are interested in the action of ion beams, used for therapeutic purposes or to increase the biological diversity. In general, the assessment of the damage that radiation produces both in the target objects and in the surrounding tissues, requires considerable time because is based on biochemical analysis or on the examination of the evolution of the irradiated systems. The delayed luminescence technique could help to simplify this investigation. We have so started our studies performing irradiations of some relatively simple vegetable models. In this paper we report results obtained from mung bean (Vigna radiata) seeds submitted to a 12C ion beam at the energy of 62 MeV/nucleon. The dry seeds were irradiated at doses from 50 to 7000 Gy. The photoinduced delayed luminescence of each seed before and after ion irradiation was measured. The growth of seedlings after irradiation was compared with that of untreated seeds. A growth reduction on increasing the dose was registered. The results show strong correlations between the ion irradiation dose, seeds growth and delayed luminescence intensity. In particular, the delayed luminescence intensity is correlated by a logistic function to the seedlings elongation and, after performing a suitable measurement campaign based on blind tests, it could become a tool able to predict the growth of seeds after ion irradiation. Moreover these results demonstrate that measurements of delayed luminescence could be used as a fast and non-invasive technique to check the effects of ion beams on relatively simple biological systems. PMID:27936220

  6. Assessing the irradiance delivered from light-curing units in private dental offices in Jordan.

    PubMed

    Maghaireh, Ghada A; Alzraikat, Hanan; Taha, Nessrin A

    2013-08-01

    The authors conducted a study to examine the irradiance from light-curing units (LCUs) used in dental offices in Jordan. Two of the authors visited 295 private dental offices (15 percent) in Jordan and collected the following information about the LCUs: age, type (quartz-tungsten-halogen or light-emitting diode), date of last maintenance, type of maintenance, last date of use, number of times used during the day, availability of a radiometer, exposure time for each resin-based composite increment, size of light-curing tips and presence of resin-based composite on the tips. The authors used a radiometer to measure the irradiance from the LCUs. They used linear regression with stepwise correlation for the statistical analysis. The authors set the minimum acceptable irradiance at 300 milliwatts/square centimeter. The mean irradiance of the 295 LCUs examined was 361 mW/cm(2), and 136 LCUs (46.1 percent) delivered an irradiance of less than 300 mW/cm(2). The unit's age, type and presence of resin-based composite on the light-curing tips had a significant effect on the irradiance (P ≤ .001). Only 37 of the 141 quartz-tungsten-halogen units (26.2 percent) and 122 of the 154 light-emitting diode units (79.2 percent) delivered at least 300 mW/cm(2). Resin contamination on the light-curing tips had a significant effect on the irradiance delivered. The irradiance from the LCUs decreased with use. Practical Implications. The irradiance from many of the units in this study was less than 300 mW/cm(2), which may affect the quality of resin-based composite restorations. Dentists should monitor the performance of the LCUs in their offices weekly.

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

    SciTech Connect

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

    1996-04-01

    Amorphization cannot be tolerated in ceramics proposed for fusion energy applications due to the accompanying large volume change ({approx} 15% in SiC) and loss of strength. Ion beam irradiations at temperatures between 200 K and 450 K were used to examine the likelihood of amorphization in ceramics being considered for the structure (SiC) and numerous diagnostic and plasma heating systems (MgAl{sub 2}O{sub 4}, Al{sub 2}O{sub 3}, MgO, Si{sub 3}N{sub 4}) in fusion energy systems. The microstructures were examined following irradiation using cross-section transmission electron microscopy. The materials in this study included ceramics with predominantly covalent bonding (SiC, Si{sub 3}N{sub 4}) and predominantely ionic bonding (MgAl{sub 2}O{sub 4}, Al{sub 2}O{sub 3}, MgO). The samples were irradiated with a variety of ion beams (including some simultaneous dual ion beam irradiations) in order to investigate possible irradiation spectrum effects. The ion energies were >0.5 MeV in all cases, so that the displacement damage effects could be examined in regions well separated from the implanted ion region.

  8. Effect of oxygen ion irradiation on dielectric, structural, chemical and thermoluminescence properties of natural muscovite mica.

    PubMed

    Kaur, Sukhnandan; Singh, Surinder; Singh, Lakhwant

    2017-03-01

    Thin cleaved samples (~18µm) of natural muscovite mica were irradiated with 80MeV oxygen ion beam at fluence ranging from 1×10(12) to 5×10(13)ion/cm(2). The alterations in dielectric, structural, chemical and thermoluminescence properties of irradiated as well as pristine samples have been investigated. Dielectric constant decreases while other dielectric parameters such as dielectric loss, tanδ, ac conductivity, real and imaginary parts of electric modulus increase with increase of ion fluence. Williamson Hall investigation has been utilized to ascertain crystallite size and micro strain of pristine and irradiated samples. The XRD analysis revealed a significant increase in micro strain and dislocation density with an increase of ion fluence. The variations in dielectric properties upon irradiation are collaborated with structural modifications in the muscovite. No appreciable changes in characteristic bands (FTIR) have been observed after irradiation, indicating that natural muscovite mica is chemically stable. Natural muscovite mica has eminent applications in heavy ions dosimetry due to observation of well defined single peak at 303°C with activation energy of 1.24eV in TL spectrum.

  9. The conductivity of high-fluence noble gas ion irradiated CVD polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Borisov, A. M.; Kazakov, V. A.; Mashkova, E. S.; Ovchinnikov, M. A.; Shemukhin, A. A.; Sigalaev, S. K.

    2017-09-01

    The conductivity of surface layer of polycrystalline CVD (Chemical Vapor Deposition) diamond has been studied experimentally after high-fluence 30 keV Ne+, 20 and 30 keV Ar+ ion irradiation at target temperature range from 30 to 400 °C. The hot ion irradiation of CVD diamond may be described as ion-stimulated heat graphitization in which an exponential resistance decrease with increasing of the irradiation temperature is much faster than at the heat treatment. Under ion irradiation of CVD diamond the graphite-like materials resistivity is achieved at temperatures not exceeding 200 °C. The graphite phase in a heterogeneous structure of diamond irradiated layer is in dynamic equilibrium. In the temperature range from RT to 400 °C, the proportion of graphite phase increases so that at temperatures 200 < Tir < 400 °C it is dominant. The Raman spectra of ion-induced conductive layer created on CVD diamond reflect the processes of nanostructural ordering - disordering of sp2-bonded carbon.

  10. Swift heavy ion irradiation-induced enhancement in structural, conformational and electrical properties of polyaniline nanofibers

    NASA Astrophysics Data System (ADS)

    Hazarika, Jayanta; Nath, Chandrani; Kumar, A.

    2014-01-01

    We report here the irradiation effects of 160 MeV Ni12+ ion beam on the structural and electrical properties of polyaniline (PAni) nanofibers synthesized by the interfacial polymerization method. The morphological studies show an increase in average diameter of PAni nanofibers upon swift heavy ion (SHI) irradiation. X-ray diffraction results show the amorphous nature of PAni nanofibers and upon SHI irradiation its crystallinity (K) and average crystallite size or extent of order (L) increase with increasing ion fluence. Fourier transform infrared spectroscopy results confirm the formation of PAni and suggest better conjugation length of PAni chains with increasing ion fluence. The ac conductivity follows the universal power law, σac=A ωs with (0irradiation conductivity increases appreciably with fluence. The decreasing behavior of frequency exponent s with temperature suggests correlated barrier hopping transport of charge carriers. Current-voltage characteristics of PAni nanofibers show the non-ohmic behavior and the current increases with increasing ion fluence. Thermogravimetric analysis exhibits enhanced thermal stability of PAni nanofibers upon SHI irradiation.

  11. Optical and dielectric properties of ion beam irradiated Ag/polymethyl methacrylate nanocomposites.

    PubMed

    Gavade, Chaitali; Singh, N L; Khanna, P K

    2014-08-01

    Changes in the dielectric, optical, structural and thermal properties of PMMA/silver nanocomposites of different concentrations of silver nanoparticles (5%, 10%, 15%) due to swift heavy ion irradiation were studied by means of impedance gain phase analyzer, UV-visible spectroscopy, X-ray diffraction and differential scanning calorimetry. Samples were irradiated with 120 MeV Si-ions at fluences of 1 x 10(11), 1 x 10(12) ions/cm2. Dependence of dielectric properties on frequency, ion beam fluence and filler concentration was studied. The results revealed the enhancement in dielectric properties after dopping nanoparticles and also upon irradiation. Optical properties like band gap was estimated for pure polymer and nanocomposite films from their optical absorption spectra in the wavelength region 200-800 nm. It was found that the band gap value shifted to lower energy (from 4.58 eV to 3.21 eV) on doping with silver nanoparticles. Differential scanning calorimetry analysis revealed a decrease in the glass transition temperature upon irradiation, which may be attributed to scissioning of polymer chain due to ion beam irradiation which is also confirmed with XRD analysis.

  12. TiO2 films photocatalytic activity improvements by swift heavy ions irradiation

    NASA Astrophysics Data System (ADS)

    Rafik, Hazem; Mahmoud, Izerrouken; Mohamed, Trari; Abdenacer, Benyagoub

    2014-08-01

    TiO2 thin films synthesized by sol-gel on glass substrates are irradiated by 90 MeV Xe ions at various fluences and room temperature under normal incidence. The structural, electrical, optical and surface topography properties before and after Xe ions irradiation are investigated. X-ray diffraction (XRD) reveals that the crystallinity is gradually destroyed, and the films become amorphous above 5×1012 ions/cm2. The band gap is not affected by Xe ions irradiation as evidenced from the optical measurements. By contrast, the conductivity increases with raising Xe fluence. The energy band diagram established from the electrochemical characterization shows the feasibility of TiO2 films for the photo-electrochemical chromate reduction. Xe ion irradiation results in enhanced photocatalytic activity in aquatic medium, evaluated by the reduction of Cr(VI) into trivalent state. TiO2 films irradiated at 1013 Xe/cm2 exhibit the highest photoactivity; 69% of chromate (10 ppm) is reduced at pH 3 after 4 h of exposure to sunlight (1120 mW cm-2) with a quantum yield of 0.06%.

  13. Effect of Grazing Angle Cross-Ion Irradiation on Ag Thin Films

    NASA Astrophysics Data System (ADS)

    Kumar, Manish; Jangid, Teena; Panchal, Vandana; Kumar, Praveen; Pathak, Abhishek

    2016-10-01

    Apart from the spherical shape, control over other shapes is a technical challenge in synthesis approaches of nanostructures. Here, we studied the effect of grazing angle cross-irradiation Ag thin films for the nanostructures evolution from a top-down approach. Ag thin films of different thicknesses were deposited on Si (100) and glass substrates by electron beam evaporation system and subsequently irradiated at grazing angle ions by 80 keV Ar+ in two steps (to induce effectively a cross-ion irradiation). Pristine films exhibited dense and uniform distribution of Ag nanoparticles with their characteristic surface plasmon resonance-induced absorption peak around 420 nm. When the film surfaces were treated with cross-grazing angle irradiation of Ar ions with varying effective fluences from 0.5 × 1017 ions/cm2 to 2.0 × 1017 ions/cm2, it was found that fluence values governed the competition of sputtering and sputter re-deposition of Ag. As a result, lower irradiation fluence favoured the formation of cone-like nanostructures, whereas high fluence values demonstrated dominant sputtering. Fluence-dependent modification of surface features was studied through the Fourier transform infrared spectroscopy and the Rutherford backscattering spectroscopy. Theoretical justifications for the underlying mechanisms are presented to justify the experimental results.

  14. A molecular dynamics analysis of ion irradiation of ultrathin amorphous carbon films

    NASA Astrophysics Data System (ADS)

    Qi, J.; Komvopoulos, K.

    2016-09-01

    Molecular dynamics (MD) simulations provide insight into nanoscale problems where continuum description breaks down, such as the modeling of ultrathin films. Amorphous carbon (a-C) films are commonly used as protective overcoats in various contemporary technologies, including microelectromechanical systems, bio-implantable devices, optical lenses, and hard-disk drives. In all of these technologies, the protective a-C film must be continuous and very thin. For example, to achieve high storage densities (e.g., on the order of 1 Tb/in.2) in magnetic recording, the thickness of the a-C film used to protect the magnetic media and the recording head against mechanical wear and corrosion must be 2-3 nm. Inert ion irradiation is an effective post-deposition method for reducing the film thickness, while preserving the mechanical and chemical characteristics. In this study, MD simulations of Ar+ ion irradiated a-C films were performed to elucidate the effects of the ion incidence angle and ion kinetic energy on the film thickness and structure. The MD results reveal that the film etching rate exhibits a strong dependence on the ion kinetic energy and ion incidence angle, with a maximum etching rate corresponding to an ion incidence angle of ˜20°. It is also shown that Ar+ ion irradiation mainly affects the structure of the upper half of the ultrathin a-C film and that carbon atom hybridization is a strong function of the ion kinetic energy and ion incidence angle. The results of this study elucidate the effects of important ion irradiation parameters on the structure and thickness of ultrathin films and provide fundamental insight into the physics of dry etching.

  15. Heavy ion irradiation induced dislocation loops in AREVA's M5® alloy

    NASA Astrophysics Data System (ADS)

    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

    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.

  16. Response of nanostructured ferritic alloys to high-dose heavy ion irradiation

    SciTech Connect

    Parish, Chad M.; White, Ryan M.; LeBeau, James M.; Miller, Michael K.

    2014-02-01

    A latest-generation aberration-corrected scanning/transmission electron microscope (STEM) is used to study heavy-ion-irradiated nanostructured ferritic alloys (NFAs). Results are presented for STEM X-ray mapping of NFA 14YWT irradiated with 10 MeV Pt to 16 or 160 dpa at -100°C and 750°C, as well as pre-irradiation reference material. Irradiation at -100°C results in ballistic destruction of the beneficial microstructural features present in the pre-irradiated reference material, such as Ti-Y-O nanoclusters (NCs) and grain boundary (GB) segregation. Irradiation at 750°C retains these beneficial features, but indicates some coarsening of the NCs, diffusion of Al to the NCs, and a reduction of the Cr-W GB segregation (or solute excess) content. Ion irradiation combined with the latest-generation STEM hardware allows for rapid screening of fusion candidate materials and improved understanding of irradiation-induced microstructural changes in NFAs.

  17. Dynamical response of helium bubble motion to irradiation with high-energy self-ions in aluminum at high temperature.

    SciTech Connect

    Ono, K.; Miyamoto, M.; Arakawa, K.; Birtcher, R. C.; Materials Science Division; Shimane Univ.; Osaka Univ.

    2009-02-21

    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.

  18. Nanoscale η-NiSi formation via ion irradiation of Si/Ni/Si

    NASA Astrophysics Data System (ADS)

    Banu, Nasrin; Satpati, Biswarup; Bhukta, Anjan; Dev, B. N.

    2017-01-01

    Nickel monosilicide (NiSi) has emerged as an excellent material of choice for source-drain contact applications below 45 nm node complementary metal-oxide-semiconductor technology. We have investigated the formation of nanoscale NiSi by ion irradiation of Si (˜5 nm)/Ni(˜15 nm)/Si, grown in an ultrahigh vacuum environment. Irradiation was carried out at room temperature with 1 MeV Si+ ions. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed for analysis. With increasing ion fluence, ion beam mixing occurs and more and more Si is incorporated into the Ni layer, and this layer gets amorphized. At an even higher fluence, a recrystallized uniform nickel monosilicide (η-NiSi) layer is formed. Several planar spacings of different Miller indices of η-NiSi have been observed in XRD and TEM. Additionally, an interesting amorphization and recrystallization behavior has been observed in the substrate Si with increasing ion fluence. To our knowledge, this has never been observed in ion irradiation of bare Si in decades of work in this area. This kind of amorphization/recrystallization in Si is apparently Ni-induced. Irradiation displaces Ni and produces a distribution of Ni in amorphized Si. Irradiation at a higher fluence produces two recrystallized Si bands in amorphous Si with concomitant accumulation of Ni at the amorphous/crystalline interfaces. On a further increase in irradiation fluence, the recrystallized Si bands again pass through amorphization and recrystallization. The total thickness of recrystallized, as well as amorphous Si, shows an oscillatory behavior as a function of ion fluence.

  19. Ultraviolet Spectral Changes in Amorphous Carbon Grains Induced by Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Mennella, V.; Baratta, G. A.; Colangeli, L.; Palumbo, P.; Rotundi, A.; Bussoletti, E.; Strazzulla, G.

    1997-05-01

    Small carbon grains, processed by UV radiation and cosmic rays, have been proposed as carriers of the 217.5 nm bump present in the interstellar extinction curves (Hecht 1986; Sorrell 1990). In this paper, we present the results of an experiment aimed at simulating, in a first approximation, the cosmic-ray irradiation active in space. We have studied the effects induced by 3 keV He+ ions on the UV spectrum of small cosmic analog carbon grains. Two different kinds of grains have been analyzed. They were produced by vapor condensation in hydrogen and argon quenching atmospheres. Spectrophotometric measurements have been carried out on grains as they were produced and after ion irradiation in the spectral range 0.19-2 μm. Relevant UV spectral changes are observed after ion irradiation: while the UV absorption band shifts from 203 to 215 nm in hydrogenated amorphous carbon grains, an opposite trend is observed for the samples produced in the argon atmosphere. In this case the UV band moves from 240 to 218 nm. These spectral changes are well correlated with the optical gap variations and are therefore interpreted in terms of grain microstructure changes induced by the interactions with ions. At the highest ion fluence considered, the two carbons tend to have a similar microstructure, as testified by the UV peak position and optical gap values because of a saturation effect of the two competitive processes, amorphization and graphitization, which occur in carbon samples during ion irradiation (Compagnini & Calcagno 1996). The results of the present experiment suggest that hydrogenated amorphous carbon grains cannot be transformed into graphite grains by cosmic-ray irradiation. Moreover, the efficiency of ion irradiation in destroying well-ordered aromatic structures poses the problem of the survival itself of polycrystalline or pure graphite particles in the interstellar medium.

  20. Biodamage via shock waves initiated by irradiation with ions.

    PubMed

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

    2013-01-01

    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.

  1. Energy dependent ripple growth on Si (100) by N+ ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Bhowmik, D.; Karmakar, P.

    2017-05-01

    The energy dependence of pattern formation on Si (100) surface by N+ ion beam irradiation has been studied. Periodic ripple pattern growth has been found for low energy (5-10 keV) N+ ion bombardment at oblique incidence at a fluence of 7 × 1017 ions/cm2. The wave vector of the ripples is parallel to the ion beam direction which follows the Bradley Harper theory of ripple growth [Bradley et. al, J. Vac. Sci. Technol. A 6, 2390 (1988)]. We also found that the lateral (wavelength) and vertical (roughness) dimensions of the ripples increase with the ion energy. Ion penetration and collision cascade dimensions are calculated by Stopping and Range of Ions in Matter (SRIM). It is found that the roughness is proportional to ion penetration depth whereas the wavelength is proportional to the horizontal width of collision cascade.

  2. A New Insight of Graphene oxide-Fe(III) Complex Photochemical Behaviors under Visible Light Irradiation

    PubMed Central

    Liu, Renlan; Zhu, Xiaoying; Chen, Baoliang

    2017-01-01

    Graphene oxide (GO) contains not only aromatic carbon lattice but also carboxyl groups which enhanced the aqueous solubility of GO. To study the transformation of GO nanosheets in natural environments, GO aqueous dispersion was mixed with Fe3+ ions to form photoactive complex. Under visible light irradiation, Fe(III) of the complex would be reduced to Fe(II) which could subsequently reduce highly toxic Cr(VI) to Cr3+. The electron of the reduction was contributed by the decarboxylation of carboxyl groups on GO and iron was acting as a catalyst during the photoreduction. On the other hand, the consumption of carboxyl groups may convert GO to rGO which are tend to aggregate since the decreased electrostatic repulsion and the increased π-π attraction. The formed Cr3+ may be electrostatically adsorbed by the rGO sheets and simultaneously precipitated with the aggregated rGO sheets, resulting the effective removal of chromium and GO nanosheets from the aqueous environment. This study may shed a light on understanding the environmental transformation of GO and guide the treatment of Cr(VI). PMID:28084446

  3. A New Insight of Graphene oxide-Fe(III) Complex Photochemical Behaviors under Visible Light Irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Renlan; Zhu, Xiaoying; Chen, Baoliang

    2017-01-01

    Graphene oxide (GO) contains not only aromatic carbon lattice but also carboxyl groups which enhanced the aqueous solubility of GO. To study the transformation of GO nanosheets in natural environments, GO aqueous dispersion was mixed with Fe3+ ions to form photoactive complex. Under visible light irradiation, Fe(III) of the complex would be reduced to Fe(II) which could subsequently reduce highly toxic Cr(VI) to Cr3+. The electron of the reduction was contributed by the decarboxylation of carboxyl groups on GO and iron was acting as a catalyst during the photoreduction. On the other hand, the consumption of carboxyl groups may convert GO to rGO which are tend to aggregate since the decreased electrostatic repulsion and the increased π-π attraction. The formed Cr3+ may be electrostatically adsorbed by the rGO sheets and simultaneously precipitated with the aggregated rGO sheets, resulting the effective removal of chromium and GO nanosheets from the aqueous environment. This study may shed a light on understanding the environmental transformation of GO and guide the treatment of Cr(VI).

  4. Characterization of biodegradable polymers irradiated with swift heavy ions

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  5. Ion beam damage assessment and waveguide formation induced by energetic Si-ion irradiation in lanthanum aluminate crystal

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Huang, Q.; Crespillo, M. L.; Qiao, M.; Liu, P.; Wang, X. L.

    2017-02-01

    Lanthanum aluminate (LaAlO3) crystal has emerged as one of the most valuable functional-materials, and its physical, electronic and optical properties strongly depend on the crystal structure, which can be easily altered in an irradiation environment and therefore affect the performance of LaAlO3-based devices. On the other hand, the preparation of LaAlO3 waveguide is also a scientific challenge for its potential application prospects in optoelectronics field. In this work, the damage evolution behavior of LaAlO3 crystal under Si-ion irradiation has been discussed in detail utilizing complementary characterization techniques, and then, single-mode waveguide of LaAlO3 crystal in the visible band can be obtained based on ion-irradiation-induced lattice damage behavior. Waveguide optical-coupling techniques are used to show its competitive features. Thus, novel optical waveguides with optimized features in LaAlO3 crystals can be tailored by a proper selection of ion mass, energy and fluence using the modification of the target material during ion irradiation process.

  6. Molecular dynamics and dynamic Monte-Carlo simulation of irradiation damage with focused ion beams

    NASA Astrophysics Data System (ADS)

    Ohya, Kaoru

    2017-03-01

    The focused ion beam (FIB) has become an important tool for micro- and nanostructuring of samples such as milling, deposition and imaging. However, this leads to damage of the surface on the nanometer scale from implanted projectile ions and recoiled material atoms. It is therefore important to investigate each kind of damage quantitatively. We present a dynamic Monte-Carlo (MC) simulation code to simulate the morphological and compositional changes of a multilayered sample under ion irradiation and a molecular dynamics (MD) simulation code to simulate dose-dependent changes in the backscattering-ion (BSI)/secondary-electron (SE) yields of a crystalline sample. Recent progress in the codes for research to simulate the surface morphology and Mo/Si layers intermixing in an EUV lithography mask irradiated with FIBs, and the crystalline orientation effect on BSI and SE yields relating to the channeling contrast in scanning ion microscopes, is also presented.

  7. Direct photocatalysis for organic synthesis by using plasmonic-metal nanoparticles irradiated with visible light.

    PubMed

    Xiao, Qi; Jaatinen, Esa; Zhu, Huaiyong

    2014-11-01

    Recent advances in direct-use plasmonic-metal nanoparticles (NPs) as photocatalysts to drive organic synthesis reactions under visible-light irradiation have attracted great interest. Plasmonic-metal NPs are characterized by their strong interaction with visible light through excitation of the localized surface plasmon resonance (LSPR). Herein, we review recent developments in direct photocatalysis using plasmonic-metal NPs and their applications. We focus on the role played by the LSPR of the metal NPs in catalyzing organic transformations and, more broadly, the role that light irradiation plays in catalyzing the reactions. Through this, the reaction mechanisms that these light-excited energetic electrons promote will be highlighted. This review will be of particular interest to researchers who are designing and fabricating new plasmonic-metal NP photocatalysts by identifying important reaction mechanisms that occur through light irradiation.

  8. Low-level visible light (LLVL) irradiation promotes proliferation of mesenchymal stem cells.

    PubMed

    Lipovsky, Anat; Oron, Uri; Gedanken, Aharon; Lubart, Rachel

    2013-07-01

    Low-level visible light irradiation was found to stimulate proliferation potential of various types of cells in vitro. Stem cells in general are of significance for implantation in regenerative medicine. The aim of the present study was to investigate the effect of low-level light irradiation on the proliferation of mesenchymal stem cells (MSCs). MSCs were isolated from the bone marrow, and light irradiation was applied at energy densities of 2.4, 4.8, and 7.2 J/cm(2). Illumination of the MSCs resulted in almost twofold increase in cell number as compared to controls. Elevated reactive oxygen species and nitric oxide production was also observed in MSCs cultures following illumination with broadband visible light. The present study clearly demonstrates the ability of broadband visible light illumination to promote proliferation of MSCs in vitro. These results may have an important impact on wound healing.

  9. Corrosion behavior of Ni/sup +/-ion irradiated NiTi alloys

    SciTech Connect

    Wang, R.; Brimhall, J.L.

    1983-11-01

    Corrosion behavior of Ni/sup +/-irradiated NiTi alloys was studied in chloride solutions, together with unirradiated NiTi material with different surface conditions. Ion irradiation with either 2.5 or 5 MeV Ni/sup +/ ions transformed the NiTi surface into an amorphous layer up to 1.5 micrometers thick. Studies of corrosion potential vs time and polarization behavior indicated a small enhancement of the passivation for the Ni/sup +/-irradiated NiTi over the unirradiated NiTi. The unirradiated NiTi with a mechanically polished, course surface was susceptible to pitting and crevice corrosion attack in 1 N HCl solution. The homogeneous amorphous structure in the irradiated alloy retarded this type of localized corrosion.

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

    NASA Astrophysics Data System (ADS)

    Rolly, Gaboriaud; Fabien, Paumier; Bertrand, Lacroix

    2014-05-01

    Ion-irradiation induced diffusion and the phase transformation of a bixbyite-fluorite related rare earth oxide thin films are studied. This work is focused on yttrium sesquioxide, Y2O3, thin films deposited on Si (1 0 0) substrates using the ion beam sputtering technique (IBS). As-deposited samples were annealed ant then irradiated at cryogenic temperature (80 K) with 260 keV Xe2+ at different fluences. The irradiated thin oxide films are characterized by X-ray diffraction. A cubic to monoclinic phase transformation was observed. Analysis of this phenomenon is done in terms of residual stresses. Stress measurements as a function of irradiation fluences were realised using the XRD-sin2ψ method. Stress evolution and kinetic of the phase transformation are compared and leads to the role-played by the nucleation of point and extended defects.

  11. Surface reformation and electro-optical characteristics of liquid crystal alignment layers using ion beam irradiation

    SciTech Connect

    Oh, Byeong-Yun; Lee, Kang-Min; Kim, Byoung-Yong; Kim, Young-Hwan; Han, Jin-Woo; Han, Jeong-Min; Lee, Sang-Keuk; Seo, Dae-Shik

    2008-09-15

    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.

  12. High catalytic activity of heteropolynuclear cyanide complexes containing cobalt and platinum ions: visible-light driven water oxidation.

    PubMed

    Yamada, Yusuke; Oyama, Kohei; Gates, Rachel; Fukuzumi, Shunichi

    2015-05-04

    A near-stoichiometric amount of O2 was evolved as observed in the visible-light irradiation of an aqueous buffer (pH 8) containing [Ru(II) (2,2'-bipyridine)3 ] as a photosensitizer, Na2 S2 O8 as a sacrificial electron acceptor, and a heteropolynuclear cyanide complex as a water-oxidation catalyst. The heteropolynuclear cyanide complexes exhibited higher catalytic activity than a polynuclear cyanide complex containing only Co(III) or Pt(IV) ions as C-bound metal ions. The origin of the synergistic effect between Co and Pt ions is discussed in relation to electronic and local atomic structures of the complexes.

  13. Mechanical response to swift ion irradiation-induced nano-tracks in silica

    NASA Astrophysics Data System (ADS)

    Páramo, Ángel R.; Sordo, F.; Garoz, D.; Peña-Rodríguez, O.; Prada, A.; Olivares, J.; Crespillo, M. L.; Perlado, J. M.; Rivera, A.

    2015-06-01

    Ion irradiation on dielectric materials produces several processes, such ionization and defect formation followed by a decay governed by thermal processes such as heat diffusion and atomic rearrangement. Finally in the irradiated region the mechanical properties are altered, strain and stress fields appear, a densification takes places and other properties such as the refractive index are affected. In order to simulate the mechanical response of silica to swift ion irradiation we use a methodology based on molecular dynamics (MD) and finite element methods (FEM). We use information from MD to obtain the local densification generated by an incoming swift ion. Finally we calculate the densification in the ion track using FEM. This method provides information on the strain and stress field along the material as a function of ion irradiation fluence. For this work an experimental campaign using Br ions from 5 to 50 MeV has been done at CMAM accelerator (Madrid). We measured the refractive index and we observe that for high fluences the refractive index decreases. The effect of the strain field on the density could explain the decrease in the refractive index. We check this hypothesis using our methodology coupling MD and FEM.

  14. Effect of phototherapy with turquoise vs. blue LED light of equal irradiance in jaundiced neonates.

    PubMed

    Ebbesen, Finn; Vandborg, Pernille K; Madsen, Poul H; Trydal, Torleif; Jakobsen, Lasse H; Vreman, Hendrik J

    2016-02-01

    Blue light with peak emission around 460 nm is the preferred treatment of neonatal hyperbilirubinemia. However, studies using fluorescent light tubes have suggested that turquoise light with peak emission at 490 nm may be more efficient. At present, the predominant light source for phototherapy is light emitting diodes (LEDs). Hence, the aim of this study was to compare the bilirubin-reducing effect in jaundiced neonates treated either with turquoise or with blue LED light with peak emission at 497 or 459 nm, respectively, with equal irradiance on the infants. Infants with gestational age ≥33 wk and uncomplicated hyperbilirubinemia were randomized to either turquoise or blue LED light and were treated for 24 h. The mean irradiance footprint at skin level was 5.2 × 10(15) and 5.1 × 10(15) photons/cm(2)/s, respectively. Forty-six infants received turquoise light and 45 received blue light. The median (95% confidence interval) decrease of total serum bilirubin was 35.3% (32.5; 37.3) and 33.1% (27.1; 36.8) for infants treated with turquoise and blue lights, respectively. The difference was nonsignificant (P = 0.53). The decrease was positively correlated to postnatal age and negatively to birth weight. Using LED light of equal irradiance, turquoise and blue lights had equal bilirubin-reducing effect on hyperbilirubinemia of neonates.

  15. 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)

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

    2007-07-01

    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.

  16. Evaluation of hardening behaviors in ion-irradiated Fe-9Cr and Fe-20Cr alloys by nanoindentation technique

    NASA Astrophysics Data System (ADS)

    Li, Shilei; Wang, Yanli; Dai, Xianyuan; Liu, Fang; Li, Jinyu; Wang, Xitao

    2016-09-01

    The ion irradiation hardening behaviors of Fe-9 wt% Cr and Fe-20 wt% Cr model alloys were investigated by nanoindentation technique. The specimens were irradiated with 3 MeV Fe11+ ions at room temperature up to 1 and 5 dpa for Fe-9Cr alloy and 1 and 2.5 for Fe-20Cr alloy. The ratio of average hardness in the same depth of irradiated and unirradiated (Hirr. av/Hunirr. av) was used to determine the critical indentation depth hcrit to eliminate the softer substrate effect. The Nix-Gao model was used to explain the indentation size effect. Irradiation hardening is clearly observed in both Fe-9Cr alloy and Fe-20Cr alloy after ion irradiation. The differences of ISE and irradiation hardening behaviors between Fe-9Cr and Fe-20Cr alloys are considered to be due to their different microstructures and microstructural evolution under ion irradiation.

  17. Influence of helium-ion bombardment on the optical properties of ZnO nanorods/p-GaN light-emitting diodes.

    PubMed

    Alvi, Naveed Ul Hassan; Hussain, Sajjad; Jensen, Jen; Nur, Omer; Willander, Magnus

    2011-12-12

    Light-emitting diodes (LEDs) based on zinc oxide (ZnO) nanorods grown by vapor-liquid-solid catalytic growth method were irradiated with 2-MeV helium (He+) ions. The fabricated LEDs were irradiated with fluencies of approximately 2 × 1013 ions/cm2 and approximately 4 × 1013 ions/cm2. Scanning electron microscopy images showed that the morphology of the irradiated samples is not changed. The as-grown and He+-irradiated LEDs showed rectifying behavior with the same I-V characteristics. Photoluminescence (PL) measurements showed that there is a blue shift of approximately 0.0347 and 0.082 eV in the near-band emission (free exciton) and green emission of the irradiated ZnO nanorods, respectively. It was also observed that the PL intensity of the near-band emission was decreased after irradiation of the samples. The electroluminescence (EL) measurements of the fabricated LEDs showed that there is a blue shift of 0.125 eV in the broad green emission after irradiation and the EL intensity of violet emission approximately centered at 398 nm nearly disappeared after irradiations. The color-rendering properties show a small decrease in the color-rendering indices of 3% after 2 MeV He+ ions irradiation.

  18. Light-induced modification of plant plasma membrane ion transport.

    PubMed

    Marten, I; Deeken, R; Hedrich, R; Roelfsema, M R G

    2010-09-01

    Light is not only the driving force for electron and ion transport in the thylakoid membrane, but also regulates ion transport in various other membranes of plant cells. Light-dependent changes in ion transport at the plasma membrane and associated membrane potential changes have been studied intensively over the last century. These studies, with various species and cell types, revealed that apart from regulation by chloroplasts, plasma membrane transport can be controlled by phytochromes, phototropins or channel rhodopsins. In this review, we compare light-dependent plasma membrane responses of unicellular algae (Eremosphaera and Chlamydomonas), with those of a multicellular alga (Chara), liverworts (Conocephalum), mosses (Physcomitrella) and several angiosperm cell types. Light-dependent plasma membrane responses of Eremosphaera and Chara are characterised by the dominant role of K(+) channels during membrane potential changes. In most other species, the Ca(2+)-dependent activation of plasma membrane anion channels represents a general light-triggered event. Cell type-specific responses are likely to have evolved by modification of this general response or through the development of additional light-dependent signalling pathways. Future research to elucidate these light-activated signalling chains is likely to benefit from the recent identification of S-type anion channel genes and proteins capable of regulating these channels.

  19. Light water reactor mixed-oxide fuel irradiation experiment

    SciTech Connect

    Hodge, S.A.; Cowell, B.S.; Chang, G.S.; Ryskamp, J.M.

    1998-06-01

    The United States Department of Energy Office of Fissile Materials Disposition is sponsoring and Oak Ridge National Laboratory (ORNL) is leading an irradiation experiment to test mixed uranium-plutonium oxide (MOX) fuel made from weapons-grade (WG) plutonium. In this multiyear program, sealed capsules containing MOX fuel pellets fabricated at Los Alamos National Laboratory (LANL) are being irradiated in the Advanced Test Reactor (ATR) at the Idaho National Engineering and Environmental Laboratory (INEEL). The planned experiments will investigate the utilization of dry-processed plutonium, the effects of WG plutonium isotopics on MOX performance, and any material interactions of gallium with Zircaloy cladding.

  20. Manipulation of transport hysteresis on graphene field effect transistors with Ga ion irradiation

    SciTech Connect

    Wang, Quan; Liu, Shuai; Ren, Naifei

    2014-09-29

    We have studied the effect of Ga ion irradiation on the controllable hysteretic behavior of graphene field effect transistors fabricated on Si/SO{sub 2} substrates. The various densities of defects in graphene were monitored by Raman spectrum. It was found that the Dirac point shifted to the positive gate voltage constantly, while the hysteretic behavior was enhanced first and then weakened, with the dose of ion irradiation increasing. By contrasting the trap charges density induced by dopant and the total density of effective trap charges, it demonstrated that adsorbate doping was not the decisive factor that induced the hysteretic behavior. The tunneling between the defect sites induced by ion irradiation was also an important cause for the hysteresis.

  1. Protective effects of shikonin on brain injury induced by carbon ion beam irradiation in mice.

    PubMed

    Gan, Lu; Wang, Zhen Hua; Zhang, Hong; Zhou, Rong; Sun, Chao; Liu, Yang; Si, Jing; Liu, Yuan Yuan; Wang, Zhen Guo

    2015-02-01

    Radiation encephalopathy is the main complication of cranial radiotherapy. It can cause necrosis of brain tissue and cognitive dysfunction. Our previous work had proved that a natural antioxidant shikonin possessed protective effect on cerebral ischemic injury. Here we investigated the effects of shikonin on carbon ion beam induced radiation brain injury in mice. Pretreatment with shikonin significantly increased the SOD and CAT activities and the ratio of GSH/GSSG in mouse brain tissues compared with irradiated group (P<0.01), while obviously reduced the MDA and PCO contents and the ROS levels derived from of the brain mitochondria. The shikonin also noticeably improved the spatial memory deficits caused by carbon ion beam irradiation. All results demonstrated that shikonin could improve the irradiated brain injury which might resulted from its modulation effects on the oxidative stress induced by the 12C6+ ion beam.

  2. Automatic system for single ion/single cell irradiation based on Cracow microprobe

    NASA Astrophysics Data System (ADS)

    Veselov, O.; Polak, W.; Lekki, J.; Stachura, Z.; Lebed, K.; Styczeń, J.; Ugenskiene, R.

    2006-05-01

    Recently, the Cracow ion microprobe has found its new application as a single ion hit facility (SIHF), allowing precise irradiations of living cells by a controlled number of ions. The instrument enables a broad field of research, such as survival studies, adaptive response investigations, bystander effect, inverse dose-rate effect, low-dose hypersensitivity, etc. This work presents principles of construction and operation of the SIHF based on the Cracow microprobe. We discuss some crucial features of optical, positioning, and blanking systems, including self-developed software responsible for semiautomatic cell recognition, for precise positioning of cells, and for controlling the irradiation process. We also show some tests carried out to determine the efficiency of the whole system and of its segments. In addition, we present results of the first irradiation measurements performed with living cells.

  3. Effects of O 7+ swift heavy ion irradiation on indium oxide thin films

    NASA Astrophysics Data System (ADS)

    Gokulakrishnan, V.; Parthiban, S.; Elangovan, E.; Ramamurthi, K.; Jeganathan, K.; Kanjilal, D.; Asokan, K.; Martins, R.; Fortunato, E.

    2011-08-01

    Indium oxide thin films deposited by spray pyrolysis were irradiated by 100 MeV O 7+ ions with different fluences of 5 × 10 11, 1 × 10 12 and 1 × 10 13 ions/cm 2. X-ray diffraction analysis confirmed the structure of indium oxide with cubic bixbyite. The strongest (2 2 2) orientation observed from the as-deposited films was shifted to (4 0 0) after irradiation. Furthermore, the intensity of the (4 0 0) orientation was decreased with increasing fluence together with an increase in (2 2 2) intensity. Films irradiated with maximum fluence exhibited an amorphous component. The mobility of the as-deposited indium oxide films was decreased from ˜78.9 to 43.0 cm 2/V s, following irradiation. Films irradiated with a fluence of 5 × 10 11 ions/cm 2 showed a better combination of electrical properties, with a resistivity of 4.57 × 10 -3 Ω cm, carrier concentration of 2.2 × 10 19 cm -3 and mobility of 61.0 cm 2/V s. The average transmittance obtained from the as-deposited films decreased from ˜81% to 72%, when irradiated with a fluence of 5 × 10 11 ions/cm 2. The surface microstructures confirmed that the irregularly shaped grains seen on the surface of the as-deposited films is modified as "radish-like" morphology when irradiated with a fluence of 5 × 10 11 ions/cm 2.

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

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Keller, L. P.

    2007-01-01

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

  5. Ion channels and the transduction of light signals

    NASA Technical Reports Server (NTRS)

    Spalding, E. P.; Evans, M. L. (Principal Investigator)

    2000-01-01

    Studies of biological light-sensing mechanisms are revealing important roles for ion channels. Photosensory transduction in plants is no exception. In this article, the evidence that ion channels perform such signal-transducing functions in the complex array of mechanisms that bring about plant photomorphogenesis will be reviewed and discussed. The examples selected for discussion range from light-gradient detection in unicellular algae to the photocontrol of stem growth in Arabidopsis. Also included is some discussion of the technical aspects of studies that combine electrophysiology and photobiology.

  6. Ion channels and the transduction of light signals

    NASA Technical Reports Server (NTRS)

    Spalding, E. P.; Evans, M. L. (Principal Investigator)

    2000-01-01

    Studies of biological light-sensing mechanisms are revealing important roles for ion channels. Photosensory transduction in plants is no exception. In this article, the evidence that ion channels perform such signal-transducing functions in the complex array of mechanisms that bring about plant photomorphogenesis will be reviewed and discussed. The examples selected for discussion range from light-gradient detection in unicellular algae to the photocontrol of stem growth in Arabidopsis. Also included is some discussion of the technical aspects of studies that combine electrophysiology and photobiology.

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

    SciTech Connect

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

    2006-05-01

    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. 0.3 to 3.0 MeV/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 14.8 keV/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

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

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

    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

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

    SciTech Connect

    Zhang, Yanwen; Jiang, Weilin; Wang, Chong M.; Namavar, Fereydoon; Edmondson, Philip D.; Zhu, Zihua; Gao, Fei; Lian, Jie; Weber, William J.

    2010-11-10

    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.

  10. Nitric oxide-mediated bystander signal transduction induced by heavy-ion microbeam irradiation

    NASA Astrophysics Data System (ADS)

    Tomita, Masanori; Matsumoto, Hideki; Funayama, Tomoo; Yokota, Yuichiro; Otsuka, Kensuke; Maeda, Munetoshi; Kobayashi, Yasuhiko

    2015-07-01

    In general, a radiation-induced bystander response is known to be a cellular response induced in non-irradiated cells after receiving bystander signaling factors released from directly irradiated cells within a cell population. Bystander responses induced by high-linear energy transfer (LET) heavy ions at low fluence are an important health problem for astronauts in space. Bystander responses are mediated via physical cell-cell contact, such as gap-junction intercellular communication (GJIC) and/or diffusive factors released into the medium in cell culture conditions. Nitric oxide (NO) is a well-known major initiator/mediator of intercellular signaling within culture medium during bystander responses. In this study, we investigated the NO-mediated bystander signal transduction induced by high-LET argon (Ar)-ion microbeam irradiation of normal human fibroblasts. Foci formation by DNA double-strand break repair proteins was induced in non-irradiated cells, which were co-cultured with those irradiated by high-LET Ar-ion microbeams in the same culture plate. Foci formation was suppressed significantly by pretreatment with an NO scavenger. Furthermore, NO-mediated reproductive cell death was also induced in bystander cells. Phosphorylation of NF-κB and Akt were induced during NO-mediated bystander signaling in the irradiated and bystander cells. However, the activation of these proteins depended on the incubation time after irradiation. The accumulation of cyclooxygenase-2 (COX-2), a downstream target of NO and NF-κB, was observed in the bystander cells 6 h after irradiation but not in the directly irradiated cells. Our findings suggest that Akt- and NF-κB-dependent signaling pathways involving COX-2 play important roles in NO-mediated high-LET heavy-ion-induced bystander responses. In addition, COX-2 may be used as a molecular marker of high-LET heavy-ion-induced bystander cells to distinguish them from directly irradiated cells, although this may depend on the time

  11. Nitric oxide-mediated bystander signal transduction induced by heavy-ion microbeam irradiation.

    PubMed

    Tomita, Masanori; Matsumoto, Hideki; Funayama, Tomoo; Yokota, Yuichiro; Otsuka, Kensuke; Maeda, Munetoshi; Kobayashi, Yasuhiko

    2015-07-01

    In general, a radiation-induced bystander response is known to be a cellular response induced in non-irradiated cells after receiving bystander signaling factors released from directly irradiated cells within a cell population. Bystander responses induced by high-linear energy transfer (LET) heavy ions at low fluence are an important health problem for astronauts in space. Bystander responses are mediated via physical cell-cell contact, such as gap-junction intercellular communication (GJIC) and/or diffusive factors released into the medium in cell culture conditions. Nitric oxide (NO) is a well-known major initiator/mediator of intercellular signaling within culture medium during bystander responses. In this study, we investigated the NO-mediated bystander signal transduction induced by high-LET argon (Ar)-ion microbeam irradiation of normal human fibroblasts. Foci formation by DNA double-strand break repair proteins was induced in non-irradiated cells, which were co-cultured with those irradiated by high-LET Ar-ion microbeams in the same culture plate. Foci formation was suppressed significantly by pretreatment with an NO scavenger. Furthermore, NO-mediated reproductive cell death was also induced in bystander cells. Phosphorylation of NF-κB and Akt were induced during NO-mediated bystander signaling in the irradiated and bystander cells. However, the activation of these proteins depended on the incubation time after irradiation. The accumulation of cyclooxygenase-2 (COX-2), a downstream target of NO and NF-κB, was observed in the bystander cells 6 h after irradiation but not in the directly irradiated cells. Our findings suggest that Akt- and NF-κB-dependent signaling pathways involving COX-2 play important roles in NO-mediated high-LET heavy-ion-induced bystander responses. In addition, COX-2 may be used as a molecular marker of high-LET heavy-ion-induced bystander cells to distinguish them from directly irradiated cells, although this may depend on the time

  12. Microstructure evolution of metallic nanocrystalline thin-films under ion-beam irradiation

    NASA Astrophysics Data System (ADS)

    Kaoumi, Djamel

    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 (IVEM) at Argonne National Laboratory with Ar and Kr ions to fluences in excess of 1016 ion/cm2 at temperatures ranging from 20 to 773 K. The microstructural evolution of the thin-films was followed in situ by systematically recording bright field images and diffraction patterns at successive ion-irradiation doses. Grain growth was observed as a result of irradiation in all samples at all irradiation temperatures. The results suggest the existence of three regimes with increasing irradiating temperature: a low temperature regime (below about 0.15 to 0.22 Tm) where grain-growth does not depend on the irradiation temperature, a thermally assisted regime where both the grain-growth rate and the final grain size increase with increasing irradiation temperature, and a thermal regime where thermal effects dominate ion beam effects. Similarly to thermal grain growth, the ion-irradiation induced grain growth curves could be best fitted with curves of the type: Dn-Dn0=KF with n˜3 in the low temperature regime. The effect of solute addition on grain-growth was investigated using Zr(Fe) and Cu(Fe) supersaturated solid-solutions. In the case of Zr-Fe, Zr2Fe precipitates formed during irradiation (with the dose-to-precipitation of Zr2Fe decreasing with increasing irradiation temperature), whereas Cu-Fe remained as a solid-solution. The grain-growth rate and final size decreased in both alloys with respect to the pure metallic films as a result of second-phase particle pinning (Zener drag) (Zr-Fe), and solute drag (Cu-Fe). The grain

  13. Stability of nanosized oxides in ferrite under extremely high dose self ion irradiations

    NASA Astrophysics Data System (ADS)

    Aydogan, E.; Almirall, N.; Odette, G. R.; Maloy, S. A.; Anderoglu, O.; Shao, L.; Gigax, J. G.; Price, L.; Chen, D.; Chen, T.; Garner, F. A.; Wu, Y.; Wells, P.; Lewandowski, J. J.; Hoelzer, D. T.

    2017-04-01

    A nanostructured ferritic alloy (NFA), 14YWT, was produced in the form of thin walled tubing. The stability of the nano-oxides (NOs) was determined under 3.5 MeV Fe+2 irradiations up to a dose of ∼585 dpa at 450 °C. Transmission electron microscopy (TEM) and atom probe tomography (APT) show that severe ion irradiation results in a ∼25% reduction in size between the unirradiated and irradiated case at 270 dpa while no further reduction within the experimental error was seen at higher doses. Conversely, number density increased by ∼30% after irradiation. This 'inverse coarsening' can be rationalized by the competition between radiation driven ballistic dissolution and diffusional NO reformation. No significant changes in the composition of the matrix or NOs were observed after irradiation. Modeling the experimental results also indicated a dissolution of the particles.

  14. Stability of nanosized oxides in ferrite under extremely high dose self ion irradiations

    DOE PAGES

    Aydogan, E.; Almirall, N.; Odette, G. R.; ...

    2017-01-10

    We produced a nanostructured ferritic alloy (NFA), 14YWT, in the form of thin walled tubing. The stability of the nano-oxides (NOs) was determined under 3.5 MeV Fe+2 irradiations up to a dose of ~585 dpa at 450 °C. Transmission electron microscopy (TEM) and atom probe tomography (APT) show that severe ion irradiation results in a ~25% reduction in size between the unirradiated and irradiated case at 270 dpa while no further reduction within the experimental error was seen at higher doses. Conversely, number density increased by ~30% after irradiation. Moreover, this ‘inverse coarsening’ can be rationalized by the competition betweenmore » radiation driven ballistic dissolution and diffusional NO reformation. There were no significant changes in the composition of the matrix or NOs observed after irradiation. Modeling the experimental results also indicated a dissolution of the particles.« less

  15. Stability of nanosized oxides in ferrite under extremely high dose self ion irradiations

    DOE PAGES

    Aydogan, E.; Almirall, N.; Odette, G. R.; ...

    2017-01-10

    We produced a nanostructured ferritic alloy (NFA), 14YWT, in the form of thin walled tubing. The stability of the nano-oxides (NOs) was determined under 3.5 MeV Fe+2 irradiations up to a dose of ~585 dpa at 450 °C. Transmission electron microscopy (TEM) and atom probe tomography (APT) show that severe ion irradiation results in a ~25% reduction in size between the unirradiated and irradiated case at 270 dpa while no further reduction within the experimental error was seen at higher doses. Conversely, number density increased by ~30% after irradiation. Moreover, this ‘inverse coarsening’ can be rationalized by the competition betweenmore » radiation driven ballistic dissolution and diffusional NO reformation. There were no significant changes in the composition of the matrix or NOs observed after irradiation. Modeling the experimental results also indicated a dissolution of the particles.« less

  16. Development and performance evaluation of a three-dimensional clinostat synchronized heavy-ion irradiation system

    NASA Astrophysics Data System (ADS)

    Ikeda, Hiroko; Souda, Hikaru; Puspitasari, Anggraeini; Held, Kathryn D.; Hidema, Jun; Nikawa, Takeshi; Yoshida, Yukari; Kanai, Tatsuaki; Takahashi, Akihisa

    2017-02-01

    Outer space is an environment characterized by microgravity and space radiation, including high-energy charged particles. Astronauts are constantly exposed to both microgravity and radiation during long-term stays in space. However, many aspects of the biological effects of combined microgravity and space radiation remain unclear. We developed a new three-dimensional (3D) clinostat synchronized heavy-ion irradiation system for use in ground-based studies of the combined exposures. Our new system uses a particle accelerator and a respiratory gating system from heavy-ion radiotherapy to irradiate samples being rotated in the 3D clinostat with carbon-ion beams only when the samples are in the horizontal position. A Peltier module and special sample holder were loaded on a static stage (standing condition) and the 3D clinostat (rotation condition) to maintain a suitable temperature under atmospheric conditions. The performance of the new device was investigated with normal human fibroblasts 1BR-hTERT in a disposable closed cell culture chamber. Live imaging revealed that cellular adhesion and growth were almost the same for the standing control sample and rotation sample over 48 h. Dose flatness and symmetry were judged according to the relative density of Gafchromic films along the X-axis and Y-axis of the positions of the irradiated sample to confirm irradiation accuracy. Doses calculated using the carbon-ion calibration curve were almost the same for standing and rotation conditions, with the difference being less than 5% at 1 Gy carbon-ion irradiation. Our new device can accurately synchronize carbon-ion irradiation and simulated microgravity while maintaining the temperature under atmospheric conditions at ground level.

  17. Comparison of human lung cancer cell radiosensitivity after irradiations with therapeutic protons and carbon ions.

    PubMed

    Keta, Otilija D; Todorović, Danijela V; Bulat, Tanja M; Cirrone, Pablo Ga; Romano, Francesco; Cuttone, Giacomo; Petrović, Ivan M; Ristić Fira, Aleksandra M

    2017-05-01

    The aim of this study was to investigate effects of irradiations with the therapeutic proton and carbon ion beams in two non-small cell lung cancers, CRL5876 adenocarcinoma and HTB177 large cell lung carcinoma. The DNA damage response dynamics, cell cycle regulation, and cell death pathway activation were followed. Viability of both cell lines was lower after carbon ions compared to the therapeutic proton irradiations. HTB177 cells showed higher recovery than CRL5876 cells seven days following the treatments, but the survival rates of both cell lines were lower after exposure to carbon ions with respect to therapeutic protons. When analyzing cell cycle distribution of both CRL5876 and HTB177 cells, it was noticed that therapeutic protons predominantly induced G1 arrest, while the cells after carbon ions were arrested in G2/M phase. The results illustrated that differences in the levels of phosphorylated H2AX, a double-strand break marker, exist after therapeutic proton and carbon ion irradiations. We also observed dose- and time-dependent increase in the p53 and p21 levels after applied irradiations. Carbon ions caused larger increase in the quantity of p53 and p21 compared to therapeutic protons. These results suggested that various repair mechanisms were induced in the treated cells. Considering the fact that we have not observed any distinct change in the Bax/Bcl-2 ratio following irradiations, it seemed that different types of cell death were involved in the response to the two types of irradiations that were applied.

  18. Development and performance evaluation of a three-dimensional clinostat synchronized heavy-ion irradiation system.

    PubMed

    Ikeda, Hiroko; Souda, Hikaru; Puspitasari, Anggraeini; Held, Kathryn D; Hidema, Jun; Nikawa, Takeshi; Yoshida, Yukari; Kanai, Tatsuaki; Takahashi, Akihisa

    2017-02-01

    Outer space is an environment characterized by microgravity and space radiation, including high-energy charged particles. Astronauts are constantly exposed to both microgravity and radiation during long-term stays in space. However, many aspects of the biological effects of combined microgravity and space radiation remain unclear. We developed a new three-dimensional (3D) clinostat synchronized heavy-ion irradiation system for use in ground-based studies of the combined exposures. Our new system uses a particle accelerator and a respiratory gating system from heavy-ion radiotherapy to irradiate samples being rotated in the 3D clinostat with carbon-ion beams only when the samples are in the horizontal position. A Peltier module and special sample holder were loaded on a static stage (standing condition) and the 3D clinostat (rotation condition) to maintain a suitable temperature under atmospheric conditions. The performance of the new device was investigated with normal human fibroblasts 1BR-hTERT in a disposable closed cell culture chamber. Live imaging revealed that cellular adhesion and growth were almost the same for the standing control sample and rotation sample over 48h. Dose flatness and symmetry were judged according to the relative density of Gafchromic films along the X-axis and Y-axis of the positions of the irradiated sample to confirm irradiation accuracy. Doses calculated using the carbon-ion calibration curve were almost the same for standing and rotation conditions, with the difference being less than 5% at 1Gy carbon-ion irradiation. Our new device can accurately synchronize carbon-ion irradiation and simulated microgravity while maintaining the temperature under atmospheric conditions at ground level. Copyright © 2017 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  19. Phase stability in thermally-aged CASS CF8 under heavy ion irradiation

    SciTech Connect

    Li, Meimei; Miller, Michael K.; Chen, Wei-Ying

    2015-07-01

    The stability of the microstructure of a cast austenitic stainless steel (CASS), before and after heavy ion irradiation, was investigated by atom probe tomography (APT). A CF8 ferrite-austenite duplex alloy was thermally aged at 400 degrees C for 10,000 h. After this treatment, APT revealed nanometer-sized G-phase precipitates and Fe-rich alpha and Cr-enriched alpha' phase separated regions in the ferrite. The thermally-aged CF8 specimen was irradiated with 1 MeV Kr ions to a fluence of 1.88 x 10(19) ions/m(2) at 400 degrees C. After irradiation, APT analysis revealed a strong spatial/dose dependence of the G-phase precipitates and the alpha-alpha' spinodal decomposition in the ferrite. For the G-phase precipitates, the number density increased and the mean size decreased with increasing dose, and the particle size distribution changed considerably under irradiation. The inverse coarsening process can be described by recoil resolution. The amplitude of the alpha-alpha' spinodal decomposition in the ferrite was apparently reduced after heavy ion irradiation. (C) 2015 Elsevier B.V. All rights reserved

  20. Effect of swift heavy ion irradiation on bare and coated ZnS quantum dots

    SciTech Connect

    Chowdhury, S. Hussain, A.M.P.; Ahmed, G.A.; Singh, F.; Avasthi, D.K.; Choudhury, A.

    2008-12-01

    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.

  1. Color center annealing and ageing in electron and ion-irradiated yttria-stabilized zirconia

    NASA Astrophysics Data System (ADS)

    Costantini, Jean-Marc; Beuneu, François

    2005-04-01

    We have used X-band electron paramagnetic resonance (EPR) measurements at room-temperature (RT) to study the thermal annealing and RT ageing of color centers induced in yttria-stabilized zirconia (YSZ), i.e. ZrO2:Y with 9.5 mol% Y2O3, by swift electron and ion-irradiations. YSZ single crystals with the <1 0 0> orientation were irradiated with 2.5 MeV electrons, and implanted with 100 MeV 13C ions. Electron and ion beams produce the same two color centers, namely an F+-type center (singly ionized oxygen vacancy) and the so-called T-center (Zr3+ in a trigonal oxygen local environment) which is also produced by X-ray irradiations. Isochronal annealing was performed in air up to 973 K. For both electron and ion irradiations, the defect densities are plotted versus temperature or time at various fluences. The influence of a thermal treatment at 1373 K of the YSZ single crystals under vacuum prior to the irradiations was also investigated. In these reduced samples, color centers are found to be more stable than in as-received samples. Two kinds of recovery processes are observed depending on fluence and heat treatment.

  2. Photoinduced currents in pristine and ion irradiated kapton-H polyimide

    SciTech Connect

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

    2014-10-15

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

  3. Local magnetic field detector made by microscale ion irradiation on high temperature superconducting films

    NASA Astrophysics Data System (ADS)

    Laviano, Francesco; Gerbaldo, Roberto; Ghigo, Gianluca; Gozzelino, Laura; Minetti, Bruno; Mezzetti, Enrica

    2006-08-01

    Microscale modulations of the crystal structure in a continuous superconductor turn out to be effective for the spatial focusing of the energy dissipation induced by unpinned vortices. High-energy heavy-ion irradiation allowed the authors to finely control the defect density in order to study the properties of interfaces between pristine and irradiated parts of high temperature superconductors. In particular, strip-shaped samples were locally irradiated to create microscale modulations across their whole width. Magneto-optical imaging under electrical transport and magnetoresistive measurements imply that such tailored modulation in a superconducting strip can be exploited to develop a fully planar, single-compound, local magnetoresistive sensor.

  4. Variation of hardness and modulus of borosilicate glass irradiated with Kr ions

    NASA Astrophysics Data System (ADS)

    Peng, H. B.; Sun, M. L.; Du, X.; Yuan, W.; Yang, D.; Chen, L.; Duan, B. H.; Wang, T. S.

    2017-09-01

    Borosilicate glass has potential application for vitrification of high-level waste, which attracts extensive interest in studying their radiation durability. The NBS1 and NBS2 glasses were irradiated with 4 MeV Kr ions. The hardness and modulus of irradiated glasses were measured with a MTS G200 Nanoindenter device. With the increase of the irradiation, both the values of hardness and the modulus dropped and then saturated. The trend was consistent with previous studies, but the decay constants for the hardness of NBS1 and NBS2 were less than those in previous studies.

  5. Formation and coarsening of Ga droplets on focused-ion-beam irradiated GaAs surfaces

    SciTech Connect

    Wu, J. H.; Ye, W.; Cardozo, B. L.; Saltzman, D.; Sun, K.; Sun, H.; Mansfield, J. F.; Goldman, R. S.

    2009-10-12

    We have investigated the formation and coarsening of Ga droplets on focused-ion-beam (FIB) irradiated GaAs surfaces. To separately examine formation and coarsening, Ga droplets were fabricated by Ga{sup +} FIB irradiation of GaAs substrates with and without pre-patterned holes. We determined the droplet growth rate and size distribution as a function of FIB energy following irradiation. The data suggest a droplet formation mechanism that involves Ga precipitation from a Ga-rich layer, followed by droplet coarsening via a combination of diffusion and Ostwald ripening or coalescence via droplet migration (dynamic coalescence)

  6. [Induction of the Tn10 precise excision in E. coli cells after accelerated heavy ions irradiation].

    PubMed

    Zhuravel', D V

    2004-01-01

    The influence of the irradiation of different kinds on the induction of the structural mutations in the bacteria Escherichia coli is considered. The regularities of the Tn10 precise excision after accelerated 4He and 12C ions irradiations with different linear energy transfer (LET) were investigated. Dose dependences of the survival and relative frequency of the Tn10 precise excision were obtained. It was shown, that the relative frequency of the Tn10 precise excision is the exponential function from the irradiation dose. Relative biological efficiency (RBE), and relative genetic efficiency (RGE) were calculated, and were treated as the function of the LET.

  7. Pasteurization of grapefruit juice using a centrifugal ultraviolet light irradiator

    USDA-ARS?s Scientific Manuscript database

    The pharmaceutical industry uses UV irradiators to inactivate viruses in liquids without heat. The penetration depth of UV in some liquids, such as serum plasma, can be short. To overcome this, very thin films may be produced by centrifugal force, small diameter tubing, or other means. Many liquid f...

  8. Effects of light exposure on irradiated barium fluoride crystals

    SciTech Connect

    Wuest, C.R.; Mauger, G.J.

    1993-04-20

    Small barium fluoride crystals have been irradiated using cobalt-60 gamma rays under various illumination conditions to establish the effect of photo-bleaching of the radiation-induced color centers. This paper describes results of a few different experiments conducted at LLNL over the past few weeks.

  9. Microstructural stability of a self-ion irradiated lanthana-bearing nanostructured ferritic steel

    SciTech Connect

    Pasebani, Somayeh; Charit, Indrajit; Burns, Jatuporn; Alsagabi, Sultan; Butt, Darryl P.; Cole, James I.; Price, Lloyd M.; Shao, Lin

    2015-07-01

    Thermally stable nanofeatures with high number density are expected to impart excellent high temperature strength and irradiation stability in nanostructured ferritic steels (NFSs) which have potential applications in advanced nuclear reactors. A lanthana-bearing NFS (14LMT) developed via mechanical alloying and spark plasma sintering was used in this study. The sintered samples were irradiated by Fe2+ ions to 10, 50 and 100 dpa at 30 °C and 500 °C. Microstructural and mechanical characteristics of the irradiated samples were studied using different microscopy techniques and nanoindentation, respectively. Overall morphology and number density of the nanofeatures remained unchanged after irradiation. Average radius of nanofeatures in the irradiated sample (100 dpa at 500 °C) was slightly reduced. A notable level of irradiation hardening and enhanced dislocation activity occurred after ion irradiation except at 30 °C and ≥50 dpa. Other microstructural features like grain boundaries and high density of dislocations also provided defect sinks to assist in defect removal.

  10. Optical cavity integrated surface ion trap for enhanced light collection

    NASA Astrophysics Data System (ADS)

    Benito, Francisco M.

    Ion trap systems allow the faithful storage and manipulation of qubits encoded in the energy levels of the ions, and can be interfaced with photonic qubits that can be transmitted to connect remote quantum systems. Single photons transmitted from two remote sites, each entangled with one quantum memory, can be used to entangle distant quantum memories by interfering on a beam splitter. Efficient remote entanglement generation relies upon efficient light collection from single ions into a single mode fiber. This can be realized by integrating an ion trap with an optical cavity and employing the Purcell effect for enhancing the light collection. Remote entanglement can be used as a resource for a quantum repeater for provably secure long-distance communication or as a method for communicating within a distributed quantum information processor. We present the integration of a 1 mm optical cavity with a micro-fabricated surface ion trap. The plano-concave cavity is oriented normal to the chip surface where the planar mirror is attached underneath the trap chip. The cavity is locked using a 780 nm laser which is stabilized to Rubidium and shifted to match the 369 nm Doppler transition in Ytterbium. The linear ion trap allows ions to be shuttled in and out of the cavity mode. The Purcell enhancement of spontaneous emission into the cavity mode would then allow efficient collection of the emitted photons, enabling faster remote entanglement generation.

  11. Analysis of Heavy Ion Irradiation Induced Thermal Damage in SiC Schottky Diodes

    NASA Astrophysics Data System (ADS)

    Abbate, C.; Busatto, G.; Cova, P.; Delmonte, N.; Giuliani, F.; Iannuzzo, F.; Sanseverino, A.; Velardi, F.

    2015-02-01

    A study is presented aimed at describing phenomena involved in Single Event Burnout induced by heavy ion irradiation in SiC Schottky diodes. On the basis of experimental data obtained for 79Br irradiation at different energies, electro-thermal FEM is used to demonstrate that the failure is caused by a strong local increase of the semiconductor temperature. With respect to previous studies the temperature dependent thermal material properties were added. The critical ion energy calculated by this model is in agreement with literature experimental results. The substrate doping dependence of the SEE robustness was analyzed, proving the effectiveness of the developed model for device technological improvements.

  12. Combined High Pressure and Heavy-Ion Irradiation: a Novel Approach

    SciTech Connect

    Lang, M.; Zhang, F; Lian, J; Trautmann, C; Neumann, R; Ewing, R

    2009-01-01

    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{sub 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.

  13. Efficient modification of floral traits by heavy-ion beam irradiation on transgenic Torenia.

    PubMed

    Ohtsubo, Norihiro; Sasaki, Katsutomo; Aida, Ryutaro; Ryuto, Hiromichi; Ichida, Hiroyuki; Hayashi, Yoriko; Abe, Tomoko

    2012-01-01

    While heavy-ion beam irradiation is becoming popular technology for mutation breeding in Japan, the combination with genetic manipulation makes it more convenient to create greater variation in plant phenotypes. We have succeeded in producing over 200 varieties of transgenic torenia (Torenia fournieri Lind.) from over 2,400 regenerated plants by this procedure in only 2 years. Mutant phenotypes were observed mainly in flowers and showed wide variation in colour and shape. Higher mutation rates in the transgenics compared to those in wild type indicate the synergistic effect of genetic manipulation and heavy-ion beam irradiation, which might be advantageous to create greater variation in floral traits.

  14. Fabricating high-density magnetic storage elements by low-dose ion beam irradiation

    SciTech Connect

    Neb, R.; Sebastian, T.; Pirro, P.; Hillebrands, B.; Pofahl, S.; Schaefer, R.; Reuscher, B.

    2012-09-10

    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.

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

    SciTech Connect

    Hada, Masaki; Hontani, Yusaku; Ichiki, Kazuya; Seki, Toshio; Ibuki, Sachi; Ninomiya, Satoshi; Matsuo, Jiro; Aoki, Takaaki

    2011-01-07

    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.

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

    SciTech Connect

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

    1996-12-31

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

  17. Large scale silver nanowires network fabricated by MeV hydrogen (H+) ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Honey, S.; Naseem, S.; Ishaq, A.; Maaza, M.; Bhatti, M. T.; Wan, D.

    2016-04-01

    A random two-dimensional large scale nano-network of silver nanowires (Ag-NWs) is fabricated by MeV hydrogen (H+) ion beam irradiation. Ag-NWs are irradiated under H+ ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H+ ion beam-induced welding of Ag-NWs at intersecting positions. H+ ion beam induced welding is confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, the structure of Ag NWs remains stable under H+ ion beam, and networks are optically transparent. Morphology also remains stable under H+ ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under MeV H+ ion beam irradiation. The results exhibit that the formation of Ag-NW network proceeds through three steps: ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from MeV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices. Project supported by the National Research Foundation of South Africa (NRF), the French Centre National pour la Recherche Scientifique, iThemba-LABS, the UNESCO-UNISA Africa Chair in Nanosciences & Nanotechnology, the Third World Academy of Science (TWAS), Organization of Women in Science for the Developing World (OWSDW), the Abdus Salam ICTP via the Nanosciences African Network (NANOAFNET), and the Higher Education Commission (HEC) of Pakistan.

  18. Effect of low energy ion beam irradiation on wettability of narra ( Pterocarpus indicus) wood chips

    NASA Astrophysics Data System (ADS)

    Ramos, Henry J.; Monasterial, Jonathan Lee C.; Blantocas, Gene Q.

    2006-01-01

    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 μA 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.

  19. Silicon Carbide Power Device Performance Under Heavy-Ion Irradiation

    NASA Technical Reports Server (NTRS)

    Lauenstein, Jean-Marie; Casey, Megan; Topper, Alyson; Wilcox, Edward; Phan, Anthony; Ikpe, Stanley; LaBel, Ken

    2015-01-01

    Heavy-ion induced degradation and catastrophic failure data for SiC power MOSFETs and Schottky diodes are examined to provide insight into the challenge of single-event effect hardening of SiC power devices.

  20. Redox changes induced in hippocampal precursor cells by heavy ion irradiation.

    PubMed

    Limoli, C L; Giedzinski, E; Baure, J; Rola, R; Fike, J R

    2007-06-01

    Hippocampal precursors retain the capacity to proliferate and differentiate throughout life, and their progeny, immature neurons, can undergo neurogenesis, a process believed to be important in maintaining the cognitive health of an organism. A variety of stresses including irradiation have been shown to deplete neural precursor cells, an effect that inhibits neurogenesis and is associated with the onset of cognitive impairments. Our past work has shown that neural precursor cells exposed to X-rays or protons exhibit a prolonged increase in oxidative stress, a factor we hypothesize to be critical in regulating the function of these cells after irradiation and other stresses. Here we report that irradiation of hippocampal precursor cells with high-linear energy transfer (LET) 1 GeV/nucleon 56Fe ions leads to significantly higher levels of oxidative stress when compared to lower LET radiations (X-rays, protons). Irradiation with 1 Gy of 56Fe ions elicits twofold to fivefold higher levels of reactive oxygen species (ROS) compared to unirradiated controls, and at lower doses (ion exposure. The use of the antioxidant lipoic acid (LA) was able to reduce ROS levels below background levels when added before or after 56Fe ion irradiation. These results conclusively show that low doses of 56Fe ions can elicit significant levels of oxidative stress in neural precursor cells. Given the prevalence of heavy ions in space and the duration of interplanetary travel, these data suggest that astronauts are at risk for developing cognitive decrements. However, our results also indicate that antioxidants delivered before as radioprotective agents or after as mitigating agents hold promise as effective countermeasures for ameliorating certain adverse effects of heavy ion exposure to the CNS.

  1. Photocatalytic degradation of methylene blue on CaIn 2O 4 under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Tang, Junwang; Zou, Zhigang; Yin, Jiang; Ye, Jinhua

    2003-11-01

    Photocatalytic degradation of methylene blue (MB) dye was first investigated over the CaIn 2O 4 photocatalyst under visible light irradiation. MB was degraded largely after visible light irradiation for 120 min over the photocatalyst at room temperature in air. The high activity could be kept in a wide range of wavelength up to 580 nm. SO 42- concentration was detected as a product of MB degradation, indicating that MB was mineralized over the CaIn 2O 4 photocatalyst under visible light. The photocatalytic reaction pathway of MB degradation over the photocatalyst was also suggested.

  2. Mechanical properties and plasticity size effect of Fe-6%Cr irradiated by Fe ions and by neutrons

    NASA Astrophysics Data System (ADS)

    Hardie, C. D.; Odette, G. R.; Wu, Y.; Akhmadaliev, S.; Roberts, S. G.

    2016-12-01

    The mechanical behaviour of Fe6%Cr in the un-irradiated, self-ion irradiated and neutron irradiated conditions was measured and compared. Irradiations were performed to the same dose and at the same temperature but to very different damage rates for both methods. The materials were tested using nanoindentation and micromechanical testing, and compared with microstructural observations from Transmission Electron Microscopy (TEM) and Atom Probe Tomography (APT) reported elsewhere. Irradiated and un-irradiated micro-cantilevers with a wide range of dimensions were used to study the interrelationships between irradiation hardening and size effects in small-scale plasticity. TEM and APT results identified that the dislocation loop densities were ∼2.9 × 1022m-3 for the neutron irradiated material and only 1.4 × 1022m-3 for the ion irradiated material. Cr segregation to loops was only found for the neutron-irradiated material. The nanoindentation hardness increase due to neutron irradiation was 3 GPa and that due to ion irradiation 1 GPa. The differences between the effects of the two irradiation types are discussed, taking into account inconsistencies in damage calculations, and the differences in PKA spectra, dose rate and transmutation products for the two irradiation types.

  3. Microstructural response of InGaN to swift heavy ion irradiation

    SciTech Connect

    Zhang, L. M.; Jiang, W.; Fadanelli, R. C.; Ai, W. S.; Peng, J. X.; Wang, T. S.; Zhang, C. H.

    2016-12-01

    A monocrystalline In0.18Ga0.82N film of ~275 nm in thickness grown on a GaN/Al2O3 substrate was irradiated with 290 MeV 238U32+ ions to a fluence of 1.2 x 12 cm-2 at room temperature. The irradiated sample was characterized using helium ion microscopy (HIM), Rutherford backscattering spectrometry under ion-channeling conditions (RBS/C), and high-resolution x-ray diffraction (HRXRD). The irradiation leads to formation of ion tracks throughout the thin In0.18Ga0.82N film and the 3.0 µm thick GaN buffer layer. The mean diameter of the tracks in In0.18Ga0.82N is ~9 nm, as determined by HIM examination. Combination of the HIM and RBS/C data suggests that the material in the track is likely to be highly disordered or fully amorphized, in contrast to a crystalline structure within the ion track in GaN. Lattice relaxation in In0.18Ga0.82N and a distribution of d-spacing of the (0002) planes in GaN with lattice expansion are observed after irradiation.

  4. Amorphization of nanocrystalline monoclinic ZrO2 by swift heavy ion irradiation.

    PubMed

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

    2012-09-21

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

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

    NASA Astrophysics Data System (ADS)

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

    2004-08-01

    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 and ICS of the transistors decrease drastically after ion irradiation. Secondly, a significant increase in the collector current (IC) along with the increase in the base current (IB) after ion irradiation was observed. The radiation-induced trap levels in the collector-base depletion region of NPN transistors were studied by employing the deep level transient spectroscopy technique and different types of trap levels were observed. The results obtained on the activation energy, density of trap levels, apparent capture cross section of the defects, introduction rate and space charge layer lifetime of different defects for different total fluence are presented and discussed.

  6. Determination of cross-link density in ion-irradiated polystyrene surfaces from rippling.

    PubMed

    Karade, Yogesh; Pihan, Sascha A; Brünger, Wilhelm H; Dietzel, Andreas; Berger, Rüdiger; Graf, Karlheinz

    2009-03-03

    The irradiation of polymer surfaces with ion beams leads to pronounced chemical and physical modifications when the ions are scattered at the atoms in the polymer chain. In this way, different products of decomposition occur. Here we show that by changing the ion fluence and the mass of the ion the local mechanical properties as Young's modulus of a polystyrene surface layer can be tailored. By annealing prestretched irradiated PS near the glass transition, surface rippling occurs in the irradiated areas only, which can be described with an elastic model. The moduli obtained from rippling periodicities and elastic model assumptions are in the range between 8 and 800 MPa at the glass transition and characterize the irradiated PS as rubberlike. From these values the network density and the molar mass of entanglement are quantified. The obtained network density equals the density of hydrogen vacancies generated through the scattered ions, as confirmed by simulations of the atomic scattering and displacement processes. The obtained molar mass of entanglement reveals that the PS locally was densely cross-linked. Our results show that even for nondiscrete layered polymer systems relevant polymer parameters can be derived from the well-known surface rippling without the need for costly chemical analysis.

  7. Structural modifications of diamond like carbon films induced by MeV nitrogen ion irradiation

    NASA Astrophysics Data System (ADS)

    Mathew, S.; Bhatta, U. M.; Islam, A. K. M. Maidul; Mukherjee, M.; Ray, N. R.; Dev, B. N.

    2009-02-01

    Diamond-like carbon (DLC) films were deposited on Si(1 0 0) substrates using plasma deposition technique. The deposited films were irradiated using 2 MeV N + ions at fluences of 1×1014, 1×1015 and 5×1015 ions/cm 2. Samples have been characterized by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). Analysis of Raman spectra shows a gradual shift of both D and G band peaks towards higher frequencies along with an increase of the intensity ratio, I(D)/ I(G), with increasing ion fluence in irradiation. These results are consistent with an increase of sp 2 bonding. XPS results also show a monotonic increase of sp 2/sp 3 hybridization ratio with increasing ion fluence. Plan view TEM images show the formation of clusters in the irradiated DLC films. HRTEM micrographs from the samples irradiated at a fluence of 5×1015 ions/cm 2 show the lattice image with an average interplanar spacing of 0.34 nm, revealing that the clusters are graphite clusters. The crystallographic planes in these clusters are somewhat distorted compared to the perfect graphite structure.

  8. Development of UV Light Irradiation Patterning of Bacteriorhodopsin Thin Films for Biomimetic Functional Devices.

    PubMed

    Haruyama, Yoshihiro; Kasai, Katsuyuki; Yamada, Toshiki; Tanaka, Shukichi; Tominari, Yukihiro; Kaji, Takahiro; Kitamura, Masaya; Otomo, Akira

    2016-04-01

    We developed a new patterning method for bacteriorhodopsin (bR) thin films using UV light irradiation. The proton pump function of bR thin films can be deactivated with UV light irradiation. Inactivation of the proton pump function of bR is related to structural changes or photo-bleaching of the retinal in bR using UV light exposure, which was confirmed with absorption and Raman spectroscopy measurements. Utilizing inactivation of the proton pump function with UV light irradiation, we prepared a bR photocell with a stripe-patterned bR thin film and measured its photocurrent response. The new patterning method is applicable to complicated patterning and patterning with a higher spatial resolution, which extends the application of bR thin films as sensor devices.

  9. Damage Profiles and Ion Distribution in Pt-irradiated SiC

    SciTech Connect

    Xue, Haizhou; Zhang, Yanwen; Zhu, Zihua; Zhang, Weiming; Bae, Dr. In-Tae; Weber, William J

    2012-01-01

    Single crystalline 6H-SiC samples were irradiated at 150 K using 2MeV Pt ions. Local volume swelling is determined by electron energy loss spectroscopy (EELS), a nearly sigmoidal dependence with irradiation dose is observed. The disorder profiles and ion distribution are determined by Rutherford backscattering spectrometry (RBS), transmission electron microscopy and secondary ion mass spectrum. Since the volume swelling reaches 12% over the damage region under high ion fluence, lattice expansion is considered and corrected during the data analysis of RBS spectra to obtain depth profiles. Projectile and damage profiles are estimated by SRIM (Stopping and Range of Ions in Matter). Comparing with the measured profiles, SRIM code significantly overestimates the electronic stopping power for the slow heavy Pt ions, and large derivations are observed in the predicted ion distribution and the damage profiles. Utilizing the reciprocity method that is based on the invariance of the inelastic excitation in ion atom collisions against interchange of projectile and target, much lower electronic stopping 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. Better damage profile and ion range are predicted.

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

    SciTech Connect

    Yamamoto, Y.; Ichiki, K.; Ninomiya, S.; Matsuo, J.; Seki, T.; Aoki, T.

    2011-01-07

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

  11. Damage Profiles and Ion Distribution in Pt-irradiated SiC

    SciTech Connect

    Xue, Haizhou; Zhang, Yanwen; Zhu, Zihua; Zhang, Weiming; Bae, In-Tae; Weber, William J.

    2012-09-01

    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.

  12. Energy dependence of Ge amorphization by Ne, Ar or Kr ion irradiation

    SciTech Connect

    Birtcher, R.C.

    1994-10-01

    Ge has been irradiated at RT by Ne, Ar, or Kr ions of different energies, and the doses required for complete amorphization determined by in situ TEM and electron diffraction. Onset of amorphization was detected after the lowest ion doses reflecting amorphization by individual ions. The ion dose required for complete amorphization increased nearly linearly with ion energy over the range 0.5 to 3.5 MeV for all ions. Amorphization cross sections have been determined for all ions and energies used. The displacements per atom required for complete amorphization decreased with ion energy or mass, owing to decrease in radiation annealing of amorphous volumes as a result of a decrease in fraction of low energy transfers to Ge atoms. Increasing the relative fraction low energy transfers to Ge atoms by simultaneous 1 MeV electron irradiation increased the Kr ion dose required for complete amorphization by as much as a factor of 2.5. The effect is believed to be due to an increase in the fraction of freely migrating defects produced by low energy transfers to Ge atoms.

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

    NASA Astrophysics Data System (ADS)

    Yamamoto, Y.; Ichiki, K.; Ninomiya, S.; Seki, T.; Aoki, T.; Matsuo, J.

    2011-01-01

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

  14. Shape manipulation of ion irradiated Ag nanoparticles embedded in lithium niobate

    NASA Astrophysics Data System (ADS)

    Wolf, Steffen; Rensberg, Jura; Johannes, Andreas; Thomae, Rainer; Smit, Frederick; Neveling, Retief; Moodley, Mathew; Bierschenk, Thomas; Rodriguez, Matias; Afra, Boshra; Hasan, Shakeeb Bin; Rockstuhl, Carsten; Ridgway, Mark; Bharuth-Ram, Krish; Ronning, Carsten

    2016-04-01

    Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic 84Kr and 197Au ions, resulting in different electronic energy losses between 8.1 and 27.5 keV nm-1 in the top layer of the samples. Due to the high electronic energy losses of the irradiating ions, molten ion tracks are formed inside the lithium niobate in which the elongated Ag nanoparticles are formed. This process is strongly dependent on the initial particle size and leads to a broad aspect ratio distribution. Extinction spectra of the samples feature the extinction maximum with shoulders on either side. While the maximum is caused by numerous remaining spherical nanoparticles, the shoulders can be attributed to elongated particles. The latter could be verified by COMSOL simulations. The extinction spectra are thus a superposition of the spectra of all individual particles.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  16. Transformation of multi walled carbon nanotubes irradiated by swift heavy ions

    NASA Astrophysics Data System (ADS)

    Vishalli; Avasthi, D. K.; Srivastava, Alok; Dharamvir, Keya

    2017-09-01

    The radiation stability of multiwalled carbon nanotube (MWCNT) buckypaper (BP) has been studied under extreme conditions. Samples of thick mat of MWCNT, called buckypaper, have been prepared by vacuum filtration method and were irradiated by 120 MeV Au ions with fluences ranging from 3 × 1011 ions/cm2 to 5 × 1013 ions/cm2. The samples were characterized by Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM) and Raman spectroscopy. The surface imaging studies indicate the decrease in the average diameter of nanotubes under ion irradiation due to the sputtering of atoms from the CNT surface. Raman studies demonstrate initial healing at lower fluence, defect production at higher fluences and amorphization at highest fluence.

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

    PubMed

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

    2014-06-06

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  19. Effect of heavy-ion and electron irradiation on properties of Fe-based superconductors

    NASA Astrophysics Data System (ADS)

    Konczykowski, Marcin

    2013-03-01

    The introduction of defects by particle irradiation is used to reveal the role of disorder in matter, which is unavoidable in all crystalline solids. In superconductors defects introduce flux pinning, controlling critical current, Jc; as well as pair-breaking scattering, limiting the critical temperature, Tc. To elucidate defect related properties of Fe-based superconductors (FBS) we precede in two types of irradiation: heavy ion (6GeV Pb) to create disorder in the form of amorphous tracks and low temperature electron irradiation (2.5MeV at 20K) to create point like defects. Substantial increase of irreversible magnetization and an upward shift of the irreversibility line are observed after heavy ion irradiation of all FBS investigated to date. In BaK 122 , signatures of a Bose-glass vortex state; angular dependence and variable-range hopping flux creep are revealed. Remarkably, heavy ion irradiation does not depress Tc, however, point-like disorder introduced by electron irradiation does substantially. In isovalently substituted Ba(FeAs1 - xPx) 2 and Ba(Fe1 - x Rux As) 2 crystals, Tc decreases linearly with dose. Suppression to 40 % of initial value of Tc was achieved in Ba(FeAs1 - xPx) 2 . An increase of normal state resistivity is observed and correlated to depression of Tc. Change of superconducting gap structure with disorder was determined from penetration depth measurements, λ (T) dependence, at various stages of irradiation. Linear in T variation of pristine samples, indicative of the presence of nodes in gap, turned at low irradiation dose to exponential T variation, indica