WorldWideScience

Sample records for ion bombardment orientatsiya

  1. Ion bombardment of polyimide films

    Energy Technology Data Exchange (ETDEWEB)

    Bachman, B. J.; Vasile, M. J.

    1989-07-01

    Surface modification techniques such as wet chemical etching, oxidizing flames, and plasma treatments (inert ion sputtering and reactive ion etching) have been used to change the surface chemistry of polymers and improve adhesion. With an increase in the use of polyimides for microelectronic applications, the technique of ion sputtering to enhance polymer-to-metal adhesion is receiving increased attention. For this study, the argon-ion bombardment surfaces of pyromellitic dianhydride and oxydianiline (PMDA--ODA) and biphenyl tetracarboxylic dianhydride and phenylene diamine (BPDA--PDA) polyimide films were characterized with x-ray photoelectron spectroscopy (XPS) as a function of ion dose. Graphite and high-density polyethylene were also examined by XPS for comparison of C 1/ital s/ peak width and binding-energy assignments. Results indicate that at low ion doses the surface of the polyimide does not change chemically, although adsorbed species are eliminated. At higher doses the chemical composition is altered and is dramatically reflected in the C 1/ital s/ spectra where graphiticlike structures become evident and the prominent carbonyl peak is reduced significantly. Both polyimides demonstrate similar chemical changes after heavy ion bombardment. Atomic composition of PMDA--ODA and BPDA--PDA polymers are almost identical after heavy ion bombardment.

  2. Ion bombardment in RF photoguns

    Energy Technology Data Exchange (ETDEWEB)

    Pozdeyev,E.; Kayran, D.; Litvinenko, V. N.

    2009-05-04

    A linac-ring eRHIC design requires a high-intensity CW source of polarized electrons. An SRF gun is viable option that can deliver the required beam. Numerical simulations presented elsewhere have shown that ion bombardment can occur in an RF gun, possibly limiting lifetime of a NEA GaAs cathode. In this paper, we analytically solve the equations of motion of ions in an RF gun using the ponderomotive potential of the Rf field. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper discusses possible mitigation techniques that can reduce the rate of ion bombardment.

  3. Evolution of clusters in energetic heavy ion bombarded amorphous graphite

    CERN Document Server

    Akhtar, M N; Ahmad, Shoaib

    2016-01-01

    Carbon clusters have been generated by a novel technique of energetic heavy ion bombardment of amorphous graphite. The evolution of clusters and their subsequent fragmentation under continuing ion bombardment is revealed by detecting various clusters in the energy spectra of the direct recoils emitted as a result of collision between ions and the surface constituents.

  4. Ions Bombardment in Thin Films and Surface Processing

    Institute of Scientific and Technical Information of China (English)

    许沭华; 任兆杏

    2003-01-01

    Ions bombardment is very important in thin films and surface processing. The ionenergy and ion flux are two important parameters in ion bombardment. The ion current densitymainly dependent on the plasma density gives the number of energetic ions bombarding thesubstrate. The self-bias voltage in plasma sheath accelerates plasma ions towards the substrate.RF discharge can increase plasma density and RF bias can also provide the insulator substrate witha plasma sheath. In order to choose and control ion energy, ion density, the angle of incidence,and ion species, ion beam sources are used. New types of electrodeless ion sources (RF, MW,ECR-MW) have been introduced in detail. In the last, the effects of ion bombardment on thinfilms and surface processing are presented.

  5. Oxidation of nickel surfaces by low energy ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Saric, Iva [Faculty of Civil Engineering, University of Rijeka (Croatia); Center for Micro and Nano Sciences and Technologies, University of Rijeka (Croatia); Peter, Robert; Kavre, Ivna; Badovinac, Ivana Jelovica; Petravic, Mladen [Center for Micro and Nano Sciences and Technologies, University of Rijeka (Croatia); Department of Physics, University of Rijeka (Croatia)

    2016-03-15

    We have studied formation of oxides on Ni surfaces by low energy oxygen bombardment using X-ray photoemission spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Different oxidation states of Ni ions have been identified in XPS spectra measured around Ni 2p and O 1s core-levels. We have compared our results with thermal oxidation of Ni and shown that ion bombardment is more efficient in creating thin oxide films on Ni surfaces. The dominant Ni-oxide in both oxidation processes is NiO (Ni{sup 2+} oxidation state), while some Ni{sub 2}O{sub 3} contributions (Ni{sup 3+} oxidation state) are still present in all oxidised samples. The oxide thickness of bombarded Ni samples, as determined by SIMS, was shown to be related to the penetration depth of oxygen ions in Ni.

  6. IR and UV irradiations on ion bombarded polycrystalline silver

    Energy Technology Data Exchange (ETDEWEB)

    Latif, Anwar, E-mail: anwarlatif@uet.edu.p [Department of Physics, University of Engineering and Technology, Lahore 54890 (Pakistan); Khaleeq-ur-Rahman, M.; Bhatti, K.A.; Rafique, M.S.; Rizvi, Z.H. [Department of Physics, University of Engineering and Technology, Lahore 54890 (Pakistan)

    2010-10-15

    Ion bombarded polycrystalline fine polished silver surfaces are exposed to Nd:YAG (1064 nm, 10 mJ, 12 ns) and KrF excimer (248 nm, 57 mJ, 20 ns) lasers to examine structural and morphological changes employing X-ray diffractometry and optical microscopy, respectively. Irradiation causes considerable changes in grain sizes. Hydrodynamic sputtering is found to be dominant in heat affected zones (HAZs). Craters with irregular boundary and non-uniform thermal conduction are resulted on laser ablated surfaces of ion bombarded specimens. No disturbance takes place in the d-spacing of the planes of irradiated samples.

  7. Ion-Bombardment of X-Ray Multilayer Coatings - Comparison of Ion Etching and Ion Assisted Deposition

    NARCIS (Netherlands)

    Puik, E. J.; van der Wiel, M. J.; Zeijlemaker, H.; Verhoeven, J.

    1991-01-01

    The effects of two forms of ion bombardment treatment on the reflectivity of multilayer X-ray coatings were compared: ion etching of the metal layers, taking place after deposition, and ion bombardment during deposition, the so-called ion assisted deposition. The ion beam was an Ar+ beam of 200 eV,

  8. Cluster primary ion bombardment of organic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kollmer, F

    2004-06-15

    In order to evaluate their potential for molecular surface analysis, we applied monoatomic (Ga, Cs, Au, Bi) as well as polyatomic (SF{sub 5}, Au{sub n}, Bi{sub n}, C{sub 60}) primary ions to a series of organic samples. For the model system Irganox 1010 on LDPE we determined the secondary ion yield, the disappearance cross section and the resulting ion formation efficiency as a function of the primary ion energy. As a general result the efficiency is improved with the mass of the monoatomic primary ion. A further increase is obtained by the use of polyatomic primary ions. According to this, highest efficiencies are obtained for C{sub 60}, the lowest for Ga. Additionally, molecular imaging was performed on real world samples (electronic components, pharmaceuticals): for this a cluster LMIS operated with Ga, AuGe or Bi was applied. The results reveal the potential of cluster SIMS to overcome existing limitations and to establish TOF-SIMS for new applications in the fields of polymers, biology and medicine.

  9. Cluster primary ion bombardment of organic materials

    Science.gov (United States)

    Kollmer, F.

    2004-06-01

    In order to evaluate their potential for molecular surface analysis, we applied monoatomic (Ga, Cs, Au, Bi) as well as polyatomic (SF 5, Au n, Bi n, C 60) primary ions to a series of organic samples. For the model system Irganox 1010 on LDPE we determined the secondary ion yield, the disappearance cross section and the resulting ion formation efficiency as a function of the primary ion energy. As a general result the efficiency is improved with the mass of the monoatomic primary ion. A further increase is obtained by the use of polyatomic primary ions. According to this, highest efficiencies are obtained for C 60, the lowest for Ga. Additionally, molecular imaging was performed on real world samples (electronic components, pharmaceuticals): for this a cluster LMIS operated with Ga, AuGe or Bi was applied. The results reveal the potential of cluster SIMS to overcome existing limitations and to establish TOF-SIMS for new applications in the fields of polymers, biology and medicine.

  10. Valence-band states of ion-bombarded polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    Terrasi, A. (Istituto di Metodologie e Tecnologie per la Microelettronica, CNR, Corso Italia 57, 95129 Catania, Italy (IT)); Foti, G. (Dipartimento di Fisica, Universita di Catania, Corso Italia 57, 95129 Catania, (Italy)); Hwu, Y. (Synchrotron Radiation Center, University of Wisconsin-Madison, 3731 Schneider Drive, Stoughton, Wisconsin 53589-3097 (USA)); Margaritondo, G. (Ecole Polytechnique Federale de Lausanne, Department de Physique, PHB-Ecublens, CH 1015 Lausanne, (Switzerland))

    1991-08-01

    Ion-bombarded polystyrene with a 0.5-keV Ar{sup +} beam has been investigated by means of photoelectron spectroscopy performed with synchrotron radiation. After a dose of 10{sup 15} ions/cm{sup 2} the evolution of the valence band of the bombarded sample towards an amorphous carbonlike configuration is reported. From the analysis of valence-band spectra we estimated the out-diffusion of hydrogen and showed that its electronic states remain well identified and stable until the hydrogen presence is about 35% with respect to the pristine sample. Finally, comparison with mass spectroscopy measurements on deuterated polystyrene has been performed to determine hydrogen evolution during the ion irradiation.

  11. Thermo-mechanical design aspects of mercury bombardment ion thrusters.

    Science.gov (United States)

    Schnelker, D. E.; Kami, S.

    1972-01-01

    The mechanical design criteria are presented as background considerations for solving problems associated with the thermomechanical design of mercury ion bombardment thrusters. Various analytical procedures are used to aid in the development of thruster subassemblies and components in the fields of heat transfer, vibration, and stress analysis. Examples of these techniques which provide computer solutions to predict and control stress levels encountered during launch and operation of thruster systems are discussed. Computer models of specific examples are presented.

  12. Influence of ion beam bombardment on surface roughness of K9 glass substrate

    Science.gov (United States)

    Pan, Yongqiang; Huang, Guojun; Hang, Lingxia

    2010-10-01

    Ion beam bombardment optical substrate surface has become an important part of process of optical thin films deposition. In this work, the K9 optical glass is bombarded by the broad beam cold cathode ion source. The dependence of the K9 glass surface roughness on the ion beam bombardment time, the ion energy, the distance and incident angle are all investigated, respectively. Surface roughness of K9 glass is measured using Talysurf CCI. The experimental results show that when the ion energy is 800ev, the bombardment distance of 20cm, with the ion beam bombardment time increased, the K9 substrate surface roughness first increase and then decrease. When the ion beam bombardment distance is 20cm, bombardment time is 10min, with the bombardment energy increases, substrate surface roughness increase first and then decrease, especially in the ion energy greater than 1200ev, the optical substrate surface roughness rapidly increases. When the ion energy is 800 eV, bombardment time is 10min, with the bombardment distance increase, substrate surface roughness decrease gradually. Furthermore, the incident angle of ion beam plays an important role in improving the K9 glass surface roughness.

  13. Blistering and flaking of amorphous alloys bombarded with He ions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The blistering and flaking behavior of many kinds of amorphous al loys under helium ion bombardment at room temperature was investigated. Helium ions with energies of 40keV and 60keV were implanted within the fluence range (1.0~4.0)×1018ions/cm2. The surface topography of samples after irradiation was observed by using a scanning electron microscope. The diameter of blister and the thickness of exfoliated blister lids were measured. The results showed that many kinds of surface topography characteristics appeared for different fluences, energies and amorphous alloys, such as flaking, blistering, exfoliation, blister rupture, secondgeneration blistering and porous structure. The dependdence of surface damage modesand the critical fluence for the onset of blistering and flaking on the sort of materials and ion energy was discussed.

  14. Induction of antioxidant enzyme activity and lipid peroxidation level in ion-beam-bombarded rice seeds

    Energy Technology Data Exchange (ETDEWEB)

    Semsang, Nuananong, E-mail: nsemsang@gmail.com [Molecular Biology Laboratory, Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, LiangDeng [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2013-07-15

    Highlights: ► Ion beam bombarded rice seeds in vacuum. ► Studied seed survival from the ion bombardment. ► Determined various antioxidant enzyme activities and lipid peroxidation level. ► Discussed vacuum, ion species and ion energy effects. ► Attributed the changes to free radical formation due to ion bombardment. -- Abstract: Low-energy ion beam bombardment has been used to mutate a wide variety of plant species. To explore the indirect effects of low-energy ion beam on biological damage due to the free radical production in plant cells, the increase in antioxidant enzyme activities and lipid peroxidation level was investigated in ion-bombarded rice seeds. Local rice seeds were bombarded with nitrogen or argon ion beams at energies of 29–60 keV and ion fluences of 1 × 10{sup 16} ions cm{sup −2}. The activities of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione S-transferase (GST) and lipid peroxidation level were assayed in the germinated rice seeds after ion bombardment. The results showed most of the enzyme activities and lipid peroxidation levels in both the argon and nitrogen bombarded samples were higher than those in the natural control. N-ion bombardment could induce higher levels of antioxidant enzyme activities in the rice samples than the Ar-ion bombardment. Additional effects due to the vacuum condition were found to affect activities of some antioxidant enzymes and lipid peroxidation level. This study demonstrates that ion beam bombardment and vacuum condition could induce the antioxidant enzyme activity and lipid peroxidation level which might be due to free radical production in the bombarded rice seeds.

  15. Induction of antioxidant enzyme activity and lipid peroxidation level in ion-beam-bombarded rice seeds

    Science.gov (United States)

    Semsang, Nuananong; Yu, LiangDeng

    2013-07-01

    Low-energy ion beam bombardment has been used to mutate a wide variety of plant species. To explore the indirect effects of low-energy ion beam on biological damage due to the free radical production in plant cells, the increase in antioxidant enzyme activities and lipid peroxidation level was investigated in ion-bombarded rice seeds. Local rice seeds were bombarded with nitrogen or argon ion beams at energies of 29-60 keV and ion fluences of 1 × 1016 ions cm-2. The activities of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione S-transferase (GST) and lipid peroxidation level were assayed in the germinated rice seeds after ion bombardment. The results showed most of the enzyme activities and lipid peroxidation levels in both the argon and nitrogen bombarded samples were higher than those in the natural control. N-ion bombardment could induce higher levels of antioxidant enzyme activities in the rice samples than the Ar-ion bombardment. Additional effects due to the vacuum condition were found to affect activities of some antioxidant enzymes and lipid peroxidation level. This study demonstrates that ion beam bombardment and vacuum condition could induce the antioxidant enzyme activity and lipid peroxidation level which might be due to free radical production in the bombarded rice seeds.

  16. Molecular dynamics simulation of graphene bombardment with Si ion

    Science.gov (United States)

    Qin, Xin-Mao; Gao, Ting-Hong; Yan, Wan-Jun; Guo, Xiao-Tian; Xie, Quan

    2014-03-01

    Molecular dynamics simulations with Tersoff-Ziegler-Biersack-Littmark (Tersoff-ZBL) potential and adaptive intermolecular reactive empirical bond order (AIREBO) potential are performed to study the effect of irradiated graphene with silicon ion at several positions and energy levels of 0.1-1000 eV. The simulations reveal four processes: absorption, replacement, transmission and damage. At energies below 110 eV, the dominant process is absorption. For atom in group (a), the process that takes place is replacement, in which the silicon ion removes one carbon atom and occupies the place of the eliminated atom at the incident energy of 72-370 eV. Transmission is present at energies above 100 eV for atom in group (d). Damage is a very important process in current bombardment, and there are four types of defects: single vacancy, replacement-single vacancy, double vacancy and nanopore. The simulations provide a fundamental understanding of the silicon bombardment of graphene, and the parameters required to develop graphene-based devices by controlling defect formation.

  17. Enhanced diffusion and precipitation in Cu: In alloys due to low energy ion bombardment

    Science.gov (United States)

    Rivaud, L.; Ward, I. D.; Eltoukhy, A. H.; Greene, J. E.

    1981-01-01

    The effects of low energy Ar + ion bombardment on supersaturated Cu: 10at%-In alloys at room temperature were investigated using scanning transmission electron microscopy and Auger electron spectroscopy. Both 1 and 3 keV Ar + bombardment resulted in the preferential sputter removal of In. The surface and altered layer remained supersaturated however, and ion bombardment enhanced diffusion was sufficient to allow the precipitation of In-rich δ-phase (~30 at% In) particles in the near-surface region. The average precipitate size and number density in samples bombarded with 3 keV Ar + ions were ~200 Å and 10 10 cm -2 as compared to 150 A and 10 9 cm -2 in samples bombarded at 1 keV. The ion bombardment induced precipitates nucleated within the grains rather than, as was observed for thermally induced precipitates, at grain boundaries.

  18. Sputtering of W-Mo alloy under ion bombardment

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The distribution of plasma density in the vicinity of the W-Mo alloy source in the process of dou ble-glow discharge plasma surface alloying was diagnosed using the moveable Langmuir probe. The sputtering law, surface composition and morphological variation of the W-Mo alloy source was studied. The experimental results show that there exists obvious preferential sputtering on the surface of the W-Mo alloy source under the argon ion bombardment; the stable period is reached after a transitional period, and the preferential sputtering occurs in a definite range of composition(mole fraction): 70 % ~ 75 % Mo, 22 % ~ 25 % W; there appears segregation on the surface of the W-Mo alloy source.

  19. The influence of primary ion bombardment conditions on the secondary ion emission behavior of polymer additives

    Energy Technology Data Exchange (ETDEWEB)

    Kersting, R.; Hagenhoff, B.; Pijpers, P.; Verlaek, R

    2003-01-15

    The secondary ion (SI) emission behavior of pure polymer systems is meanwhile well understood. However, common plastics not only consist of the polymer host material but also contain a variety of additives normally present in low concentrations only. In order to better understand the parameters governing the SI emission of these trace compounds we performed a systematic study on the influence of the analysis parameters (primary ion (PI) type, PI energy, electron bombardment for charge compensation, etc.) using model systems. Samples were prepared by spin coating (sub)monolayers of Irganox 1010 onto additive-free low density polyethylene (LDPE). The SI parameters yield, disappearance cross-section and efficiency (yield per damaged area) were determined for PI bombardment with Ga{sup +}, Cs{sup +}, and SF{sub 5}{sup +}. Furthermore the damaging influence of electron bombardment for charge compensation on the organic surface layers was investigated.

  20. The influence of primary ion bombardment conditions on the secondary ion emission behavior of polymer additives

    Science.gov (United States)

    Kersting, R.; Hagenhoff, B.; Pijpers, P.; Verlaek, R.

    2003-01-01

    The secondary ion (SI) emission behavior of pure polymer systems is meanwhile well understood. However, common plastics not only consist of the polymer host material but also contain a variety of additives normally present in low concentrations only. In order to better understand the parameters governing the SI emission of these trace compounds we performed a systematic study on the influence of the analysis parameters (primary ion (PI) type, PI energy, electron bombardment for charge compensation, etc.) using model systems. Samples were prepared by spin coating (sub)monolayers of Irganox 1010 onto additive-free low density polyethylene (LDPE). The SI parameters yield, disappearance cross-section and efficiency (yield per damaged area) were determined for PI bombardment with Ga +, Cs +, and SF 5+. Furthermore the damaging influence of electron bombardment for charge compensation on the organic surface layers was investigated.

  1. Particle-In-Cell/Monte Carlo Simulation of Ion Back Bombardment in Photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Ji; Corlett, John; Staples, John

    2009-03-02

    In this paper, we report on studies of ion back bombardment in high average current dc and rf photoinjectors using a particle-in-cell/Monte Carlo method. Using H{sub 2} ion as an example, we observed that the ion density and energy deposition on the photocathode in rf guns are order of magnitude lower than that in a dc gun. A higher rf frequency helps mitigate the ion back bombardment of the cathode in rf guns.

  2. Amorphization of silicon by bombardment with oxygen ions of energy below 5 keV

    Energy Technology Data Exchange (ETDEWEB)

    Zhukovskii, P.V.; Stel' makh, V.F.; Tkachev, V.D.

    1977-04-01

    Silicon was bombarded with /sup 16/O/sup +/ ions of 1.0 and 3.0 keV energies at room temperature. This bombardment created point defects which joined up to form amorphous layers about 100 A thick. (AIP)

  3. Ionic bombardment of stainless steel by nitrogen and nickel ions immersion

    Institute of Scientific and Technical Information of China (English)

    XIONG Ling; HU Yong-jun; XU jian; MENG Ji-long

    2008-01-01

    A new nitriding process was used to carry out the ionic bombardment, in which nickel ion was introduced. The microstructure, composition and properties of the treated stainless steel were studied by means of scanning electron microscopy(SEM), micro-hardness test and electrochemistry method. The results show that the hardness of the stainless steel is greatly increased after ionic bombardment under nitrogen and nickel ions immersion. Vickers' hardness as high as Hv1268 is obtained. The bombarded stainless steel is of a little reduction in corrosion resistance, as compared with the original stainless steel. However, as compared with the traditional ion-nitriding stainless steel, the corrosion resistance is greatly improved.

  4. Mechanisms of ion-bombardment-induced DNA transfer into bacterial E. coli cells

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.D., E-mail: yuld@thep-center.org [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Sangwijit, K. [Molecular Biology Laboratory, Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Phanchaisri, B. [Institute of Science and Technology Research, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongkumkoon, P. [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thopan, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Singkarat, S. [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Anuntalabhochai, S. [Molecular Biology Laboratory, Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-05-01

    Highlights: • Ion bombardment could induce DNA transfer into E. coli cells. • The DNA transfer induction depended on ion energy and fluence. • The mechanism was associated with the bacterial cell envelope structure. • A mechanism phase diagram was proposed to summarize the mechanism. - Abstract: As a useful ion beam biotechnology, ion-bombardment-induced DNA transfer into bacterial Escherichia coli (E. coli) cells has been successfully operated using argon ions. In the process ion bombardment of the bacterial cells modifies the cell envelope materials to favor the exogenous DNA molecules to pass through the envelope to enter the cell. The occurrence of the DNA transfer induction was found ion energy and fluence dependent in a complex manner. At ion energy of a few keV and a few tens of keV to moderate fluences the DNA transfer could be induced by ion bombardment of the bacterial cells, while at the same ion energy but to high fluences DNA transfer could not be induced. On the other hand, when the ion energy was medium, about 10–20 keV, the DNA transfer could not be induced by ion bombardment of the cells. The complexity of the experimental results indicated a complex mechanism which should be related to the complex structure of the bacterial E. coli cell envelope. A phase diagram was proposed to interpret different mechanisms involved as functions of the ion energy and fluence.

  5. Tailoring surface properties of polymeric blend material by ion beam bombardment

    Science.gov (United States)

    Ali, Z. I.; Abdul-Kader, A. M.; Rizk, R. A. M.; Ali, M.

    2013-10-01

    In this work, LDPE/SBR polymer blend samples were bombarded with 130 keV He and 320 keV Ar ions at different fluencies ranging from 1×1013 to 2×1016 ions cm-2. The changes in surface properties of the ion-bombarded polymers were investigated with ultraviolet-visible (UV-vis) spectroscopy, Photoluminescence (PL) and energy dispersive X-ray (EDX) techniques. The variations in the wettability, surface free energy and spreading coefficient of ion beam bombarded LDPE polymer blend samples have been studied. The UV-vis analysis revealed that the transmission spectra shifted towards lower energy region after bombardment with increasing ion fluence. This shift clearly reflects decrease in optical band gap. A remarkable decrease in the PL intensity with increasing ion beam fluence was observed. The EDX study indicates the oxygen uptake increases with increasing ion fluence. Contact angle measurements showed that wettability, surface free energy and spreading coefficient of LDPE blends samples have increased with increasing ion fluence. This increase in the wettability and surface free energy of the bombarded samples are attributed to formation of oxidized layer on the polymer surface, which apparently occurs after exposure of bombarded samples to the air.

  6. Influence of primary ion bombardment conditions on the emission of molecular secondary ions

    Energy Technology Data Exchange (ETDEWEB)

    Kersting, R.; Hagenhoff, B.; Kollmer, F.; Moellers, R.; Niehuis, E

    2004-06-15

    In order to further our understanding of the secondary ion emission behavior from organic surfaces, we have performed a systematic study on the influence of the primary ion parameters. As model sample Irganox 1010 on low density polyethylene (LDPE) was used. Both monoatomic (Ga, Cs, Au) and polyatomic (Au{sub 2}, Au{sub 3}, SF{sub 5}, C{sub 60}) primary ions were used. Additionally, the primary ion energy was varied. The data were evaluated by calculating secondary ion yields, disappearance cross sections and ion formation efficiencies (yield/damage cross section). The results show that heavier monoatomic ions are more efficient than lighter ones and that polyatomic primary ions are more efficient than monoatomic ones. Highest efficiency values are found for C{sub 60} bombardment at 20 keV. Compared to Ga bombardment the efficiency gain in this case is more than 2000-fold. Additionally it can be shown that the higher efficiency is correlated with a softer ionization, i.e. less fragmentation. The results suggest a much more homogeneous energy distribution in the sample surface by polyatomic primary ions compared to monoatomic ones.

  7. Influence of primary ion bombardment conditions on the emission of molecular secondary ions

    Science.gov (United States)

    Kersting, R.; Hagenhoff, B.; Kollmer, F.; Möllers, R.; Niehuis, E.

    2004-06-01

    In order to further our understanding of the secondary ion emission behavior from organic surfaces, we have performed a systematic study on the influence of the primary ion parameters. As model sample Irganox 1010 on low density polyethylene (LDPE) was used. Both monoatomic (Ga, Cs, Au) and polyatomic (Au 2, Au 3, SF 5, C 60) primary ions were used. Additionally, the primary ion energy was varied. The data were evaluated by calculating secondary ion yields, disappearance cross sections and ion formation efficiencies (yield/damage cross section). The results show that heavier monoatomic ions are more efficient than lighter ones and that polyatomic primary ions are more efficient than monoatomic ones. Highest efficiency values are found for C 60 bombardment at 20 keV. Compared to Ga bombardment the efficiency gain in this case is more than 2000-fold. Additionally it can be shown that the higher efficiency is correlated with a softer ionization, i.e. less fragmentation. The results suggest a much more homogeneous energy distribution in the sample surface by polyatomic primary ions compared to monoatomic ones.

  8. Self-heating effect induced by ion bombardment on polycrystalline Al surface nanostructures evolution

    Indian Academy of Sciences (India)

    H Wang; Y Zhen; H Wjiang; J T Liu

    2012-06-01

    We studied the self-heating effect during ion bombardment process on polycrystalline Al foils. An anisotropic surface morphology evolution has been observed. The adjacent peaks’ fusion along the direction perpendicular to the ion beam projection smoothen the surface. Fusion along the parallel direction has been suppressed due to Ar+ ion bombardment. It attributes to the result of the competition between the isotropic thermal effect, due to the self-heating effect by energy exchange between incident ions and Al surface, and the suppression by continuous ion bombardment with a certain incident angle. Varying the incident ion beam angle with the angular range 32° < < 82°, the ripple wave vector, , is found to be parallel to the ion beam direction, whereas for > 82° , is perpendicular to the beam direction. The critical angle, c, is close to 82°, which is different from Bradley and Harper’s prediction and attributes to the self-heating effect.

  9. Influence of the ion bombardment of O{sub 2} plasmas on low-k materials

    Energy Technology Data Exchange (ETDEWEB)

    Verdonck, Patrick, E-mail: verdonck@imec.be [IMEC, Kapeldreef 75, 3001 Leuven (Belgium); Samara, Vladimir [IMEC, Kapeldreef 75, 3001 Leuven (Belgium); Open University, Materials Engineering, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Goodyear, Alec [Open University, Materials Engineering, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Ferchichi, Abdelkarim; Van Besien, Els; Baklanov, Mikhail R. [IMEC, Kapeldreef 75, 3001 Leuven (Belgium); Braithwaite, Nicholas [Open University, Department of Physics and Astronomy, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2011-10-31

    In this study, special tests were devised in order to investigate the influence of ion bombardment on the damage induced in low-k dielectrics by oxygen plasmas. By placing a sample that suffered a lot of ion bombardment and one which suffered little ion bombardment simultaneously in the same plasma, it was possible to verify that ion bombardment in fact helped to protect the low-k film against oxygen plasma induced damage. Exhaustive analyses (ellipsometry, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, porosimetry, capacitance-voltage (C-V) measurements, water contact angle analysis) show that ion bombardment induced the formation of a denser top layer in the film, which then hampered further penetration of active oxygen species deeper into the bulk. This was further confirmed by other tests combining capacitively and inductively coupled plasmas. Therefore, it was possible to conclude that, at least for these plasmas, ion bombardment may help to reduce plasma induced damage to low-k materials.

  10. Scanning tunneling microscopy and spectroscopy of ion-bombarded Si(111) and Si(100) surfaces

    NARCIS (Netherlands)

    Zandvliet, H.J.W.; Elswijk, H.B.; Loenen, van E.J.; Tsong, I.S.T.

    1992-01-01

    Surfaces of Si(111)-(7×7) and Si(100)-(2×1) were bombarded by 3-keV Ar+ ions at doses of ≤1012 ions cm-2 to study the effect of individual ion impacts on the atomic structure of surfaces. Atom-resolved images show damaged regions of missing and displaced atoms. Current-imaging tunneling spectroscop

  11. Low energy ion bombardment enhanced diffusion, segregation, and phase transformations in Cu:In alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rivaud, L.; Eltoukhy, A.H.; Greene, J.E. (Illinois Univ., Urbana (USA). Materials Research Lab.; Illinois Univ., Urbana (USA). Coordinated Science Lab.; Illinois Univ., Urbana (USA). Dept. of Metallurgy and Mining Engineering)

    1982-04-01

    Scanning transmission electron microscopy and Auger electron spectroscopy were used to investigate the effects of low energy Ar/sup +/ ion bombardment of supersaturated Cu:In alloys. Ion bombardment always resulted in the preferential sputtering of In although for sample temperatures Tsub(s) approximately > 250/sup 0/C, In loss due to preferential sputtering was increasingly compensated by radiation enhanced surface segregation. At room temperature, the steady state In concentration in the altered layer during irradiation remained supersaturated and enhanced diffusion to ion bombardment-created point defect sinks resulted in the volume precipitation of randomly dispersed In-rich delta phase particles in the near-surface region. Thermally induced precipitates nucleated only at grain boundaries and were only observed at Tsub(s) >= 250/sup 0/C. The average size and number density of radiation-induced precipitates increased with increasing ion bombardment energy Esub(f). Upon termination of ion bombardment at Tsub(s) >= 250/sup 0/C, the In surface concentration always returned to approximately 30 at%. The recovery time for this process decreased with increasing Tsub(s) and Esub(f) due to fast diffusion through near-surface regions containing residual damage such as dislocation loops. The measured widths of the compositionally altered layers were on the order of the ion penetration range.

  12. Nanometer-scale sharpening and surface roughening of ZnO nanorods by argon ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Chatterjee, Shyamal, E-mail: shyamal@iitbbs.ac.in [School of Basic Sciences, Indian Institute of Technology, Bhubaneswar 751013 (India); Behera, Akshaya K. [School of Basic Sciences, Indian Institute of Technology, Bhubaneswar 751013 (India); Banerjee, Amarabha; Tribedi, Lokesh C. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Som, Tapobrata [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Ayyub, Pushan, E-mail: pushan@tifr.res.in [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2012-07-01

    We report the effects of exposing a hydrothermally grown, single crystalline ZnO nanorod array to a beam of 50 keV argon ions at room temperature. High resolution electron microscopy reveals that the ion bombardment results in a nanometer-scale roughening of the nanorod sidewalls, which were almost atomically flat in the pristine sample. Ion bombardment further causes the flat, Almost-Equal-To 100 nm diameter nanorod tips to get sharpened to ultrafine points less than 10 nm across. While tip sharpening is attributed to preferential sputtering, the formation of crystalline surface protuberances can be ascribed to surface instability due to curvature dependent sputtering and surface diffusion under argon-ion bombardment. Both the nanoscale roughening as well as the tip sharpening are expected to favorably impact a wide variety of applications, such as those involving catalysis, gas sensing, solar cells, field emission and gas discharge.

  13. Enhanced End-Contacts by Helium Ion Bombardment to Improve Graphene-Metal Contacts

    Directory of Open Access Journals (Sweden)

    Kunpeng Jia

    2016-08-01

    Full Text Available Low contact resistance between graphene and metals is of paramount importance to fabricate high performance graphene-based devices. In this paper, the impact of both defects induced by helium ion (He+ bombardment and annealing on the contact resistance between graphene and various metals (Ag, Pd, and Pt were systematically explored. It is found that the contact resistances between all metals and graphene are remarkably reduced after annealing, indicating that not only chemically adsorbed metal (Pd but also physically adsorbed metals (Ag and Pt readily form end-contacts at intrinsic defect locations in graphene. In order to further improve the contact properties between Ag, Pd, and Pt metals and graphene, a novel method in which self-aligned He+ bombardment to induce exotic defects in graphene and subsequent thermal annealing to form end-contacts was proposed. By using this method, the contact resistance is reduced significantly by 15.1% and 40.1% for Ag/graphene and Pd/graphene contacts with He+ bombardment compared to their counterparts without He+ bombardment. For the Pt/graphene contact, the contact resistance is, however, not reduced as anticipated with He+ bombardment and this might be ascribed to either inappropriate He+ bombardment dose, or inapplicable method of He+ bombardment in reducing contact resistance for Pt/graphene contact. The joint efforts of as-formed end-contacts and excess created defects in graphene are discussed as the cause responsible for the reduction of contact resistance.

  14. On the origin of microcraters on the surface of ion beam bombarded plant cell walls

    Science.gov (United States)

    Salvadori, M. C.; Teixeira, F. S.; Brown, I. G.

    2006-01-01

    Ion bombardment of plant and bacterial cellular material has recently been used as a tool for the transfer of exogenous DNA macromolecules into the cell interior region. The precise mechanism that leads to the transfer of macromolecules through the cell envelope is not yet clear, however it has been observed that the ion bombardment is accompanied by the formation of "microcraters" on the cell wall, and it is possible that these features provide channels for the macromolecule transfer. Thus the nature and origin of the microcraters is of importance to understanding the DNA transfer phenomenon as well as being of fundamental interest. We report here on some scanning electron microscope observations we have made of onion skin cells that have been subjected to electron beam bombardment of sufficiently high power density to damage the cell wall. The damage seen is much less than and different from the microcraters formed subsequent to ion bombardment. We speculate that the microcraters may originate from the explosive release of gas generated in the biomaterial by ion bombardment.

  15. Alteration of the UV-visible reflectance spectra of H2O ice by ion bombardment

    Science.gov (United States)

    Sack, N. J.; Boring, J. W.; Johnson, R. E.; Baragiola, R. A.; Shi, M.

    1991-01-01

    Satellite in the Jovian and Saturnian system exhibit differences in reflectivity between their 'leading' and 'trailing' surfaces which can affect the local vapor pressure. Since these differences are thought to be due to differences in the flux of bombarding magnetospheric ions, the influence of ion impact on the UV-visible reflectance of water ice surfaces (20-90 K) by keV ion bombardment was studied. An observed decrease in reflectance in the UV is attributed to rearrangement processes that affect the physical microstructure and surface 'roughness'. The ratio in reflectance of bombarded to freshly deposited films is compared to the ratio of the reflectance of the leading and trailing hemispheres for Europa and Ganymede.

  16. Alteration of the UV-visible reflectance spectra of H2O ice by ion bombardment

    Science.gov (United States)

    Sack, N. J.; Boring, J. W.; Johnson, R. E.; Baragiola, R. A.; Shi, M.

    1991-01-01

    Satellite in the Jovian and Saturnian system exhibit differences in reflectivity between their 'leading' and 'trailing' surfaces which can affect the local vapor pressure. Since these differences are thought to be due to differences in the flux of bombarding magnetospheric ions, the influence of ion impact on the UV-visible reflectance of water ice surfaces (20-90 K) by keV ion bombardment was studied. An observed decrease in reflectance in the UV is attributed to rearrangement processes that affect the physical microstructure and surface 'roughness'. The ratio in reflectance of bombarded to freshly deposited films is compared to the ratio of the reflectance of the leading and trailing hemispheres for Europa and Ganymede.

  17. Effects of low and high energy ion bombardment on ETFE polymer

    Science.gov (United States)

    Minamisawa, R. A.; De Almeida, A.; Abidzina, V.; Parada, M. A.; Muntele, I.; Ila, D.

    2007-04-01

    The polymer ethylenetetrafluoroethylene (ETFE) is used as anti-adherent coatings for food packages and radiation dosimeters. In this work, we compare the damage induced in ETFE bombarded with 100 keV Si ions with that induced by 1 MeV proton bombardment. The damage depends on the type, energy and intensity of the irradiation. Irradiated films were analyzed with optical absorption photospectrometry, Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy to determine the chemical nature of the structural changes caused by ion irradiation. Computer simulations were performed to evaluate the radiation damage.

  18. Direct and Recoil-Induced Electron Emission from Ion-Bombarded Solids

    DEFF Research Database (Denmark)

    Holmen, G.; Svensson, B.; Schou, Jørgen;

    1979-01-01

    atoms. The direct contribution, which has been treated by several authors in previous studies, shows a behavior that is determined primarily by the electronic stopping power of the bombarding ion, while the indirect contribution is nonproportionally related to the nuclear stopping power. This latter...

  19. Comparison of Se and Te clusters produced by ion bombardment

    Directory of Open Access Journals (Sweden)

    Trzyna Małgorzata

    2017-01-01

    Full Text Available Nanostructures based on tellurium and selenium are materials used as components for the manufacturing topological insulators. Therefore it is crucial to precisely characterize these materials. In this work the emission of selenium and tellurium cluster ions, sputtered by Bi+ primary ion guns, was investigated by using Time-of-Flight Secondary Ion Mass Spectrometry (TOF SIMS. It has been found that BixTex and BixSex clusters appear in addition to Sex and Tex clusters in the mass range up to ~ 1300 m/z. Local maxima or minima (magic numbers are observed in the ion intensity versus a number of atoms per cluster for both positive and negative ions spectra for all types of clusters and primary ions used. These extrema can be attributed to different yield and stability of certain clusters but also to fragmentation of high-mass clusters.

  20. Modelling and simulation of surface morphology driven by ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Yewande, E.O.

    2006-05-02

    Non-equilibrium surfaces, at nanometer length scales, externally driven via bombardment with energetic particles are known to exhibit well ordered patterns with a variety of applications in nano-technology. These patterns emerge at time scales on the order of minutes. Continuum theory has been quite successful in giving a general picture of the processes that interplay to give the observed patterns, as well as how such competition might determine the properties of the nanostructures. However, continuum theoretical descriptions are ideal only in the asymptotic limit. The only other theoretical alternative, which happens to be more suitable for the characteristic length-and time-scales of pattern formation, is Monte Carlo simulation. In this thesis, surface morphology is studied using discrete solid-on-solid Monte Carlo models of sputtering and surface diffusion. The simulations are performed in the context of the continuum theories and experiments. In agreement with the experiments, the ripples coarsen with time and the ripple velocity exhibits a power-law behaviour with the ripple wavelength, in addition, the exponent was found to depend on the simulation temperature, which suggests future experimental studies of flux dependence. Moreover, a detailed exploration of possible topographies, for different sputtering conditions, corresponding to different materials, was performed. And different surface topographies e.g. holes, ripples, and dots, were found at oblique incidence, without sample rotation. With sample rotation no new topography was found, its only role being to destroy any inherent anisotropy in the system. (orig.)

  1. Luminescence effects of ion-beam bombardment of CdTe surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Olvera, J., E-mail: javier.olvera@uam.e [Laboratorio de Crecimiento de Cristales, Dpto. de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Martinez, O. [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011 Valladolid (Spain); Plaza, J.L.; Dieguez, E. [Laboratorio de Crecimiento de Cristales, Dpto. de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2009-09-15

    In the present work, we report the effect of low-energy ion bombardment on CdTe surfaces. The effect is revealed by FESEM images and photoluminescence (PL) measurements carried out before and after irradiation of CdTe polycrystals by means of an ion-beam sputtering (IBS) system. An important improvement in the luminescence of CdTe was observed in the irradiated areas, related to defect-free surfaces.

  2. Mechanisms of pattern formation in grazing-incidence ion bombardment of Pt(111)

    OpenAIRE

    Hansen, H; Redinger, A.; Messlinger, S.; Stoian, G.; Rosandi, Y.; Urbassek, H. M.; Linke, U.; Michely, T.

    2006-01-01

    Ripple patterns forming on Pt(111) due to 5 keV Ar+ grazing-incidence ion bombardment were investigated by scanning tunneling microscopy in a broad temperature range from 100 to 720 K and for ion fluences up to 3x10(20) ions/m(2). A detailed morphological analysis together with molecular dynamics simulations of single ion impacts allow us to develop atomic scale models for the formation of these patterns. The large difference in step edge versus terrace damage is shown to be crucial for rippl...

  3. Neutron dose equivalent rate for heavy ion bombardment

    Institute of Scientific and Technical Information of China (English)

    LiGui-Sheng; ZhangTian-Mei; 等

    1998-01-01

    The fluence rate distribution of neutrons in the reactionsof 50MeV/u 18O-ion on thick Be,Cu and Au targets have been measured with an activation method of threshold detectors andthe neutron dose equivalent rate distributions at 1m from the tqrgets in intermediate energy heavy ion target area are obtained by using the conversion factors from neutron fluence rate to neutron doseequivalent rate.

  4. Polygonisation of ionic single crystals - a new effect of swift ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Turos, A.; Nowicki, L. [The Andrzej Soltan Institute for Nuclear Studies, Warsaw (Poland); Garrido, F.; Thome, L. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Orsay (France); Fromknecht, R. [Research Center Karlsruhe, INFP, Karlsruhe (Germany); Domagala, J. [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland)

    1999-05-01

    Isostructural oxide single crystals of the fluorite structure: stabilized cubic zirconia and UO{sub 2} were bombarded at room temperature with 72 MeV iodine ions or 340 MeV Xe ions, respectively. The aim of this paper was the study of structural transformations induced by ion bombardment in two different regimes: at 72 MeV where the radiation damage production is strongly influenced by collision cascades and at higher energies where the ionization mechanism prevails. The structure of as-grown and implanted single crystals was examined using the RBS/channeling technique and X-ray diffraction analysis. Some of the samples were also investigated by transmission electron microscopy. It was observed that the residual damage depends strongly on energy loss mechanism, and hence on the incident ion energy. At high incident energies solidification of latent tracks in UO{sub 2} leads to their polygonisation. Since the energy of 72 MeV is too low for latent track formation, the resulting damage is composed of dislocation and clusters and is similar to that created by the ion bombardment at low energies. The amount of defects was strongly enhanced by the interaction of ionised regions with collision cascades. (author) 14 refs, 4 figs

  5. CEMS studies of structural modifications of metallic glasses by ion bombardment

    Science.gov (United States)

    Miglierini, M.; Lančok, A.; Pavlovič, M.

    2010-05-01

    Fe76Mo8Cu1B15 and Fe74Nb3Cu1Si16B6 amorphous metallic alloys were exposed to ion bombardment with nitrogen ions and protons to ensure different degree of radiation damage. The radiation damage profiles were calculated in the “full cascade” mode. Conversion electron Mössbauer spectrometry was employed to scan structural modifications in the surface regions of the irradiated alloys. In Fe76Mo8Cu1B15, the irradiation with 130 keV N+ has caused a significant increase of the hyperfine magnetic fields and isomer shift due to changes in topological and chemical short-range order (SRO), respectively. No appreciable effects were revealed after bombardment with 80 keV H+ ions. Fe74Nb3Cu1Si16B6 amorphous metallic alloy was irradiated by 110 keV N+ and 37 keV H+ and only changes in chemical SRO were revealed after bombardment with nitrogen ions. The observed alternations of the structure depend primarily on the total number of displacements of the resonant atoms which are closely related to the fluence as well as type and energy of the incident ions.

  6. Optical absorption enhancement of CdTe nanostructures by low-energy nitrogen ion bombardment

    Science.gov (United States)

    Akbarnejad, E.; Ghoranneviss, M.; Mohajerzadeh, S.; Hantehzadeh, M. R.; Asl Soleimani, E.

    2016-02-01

    In this paper we present the fabrication of cadmium telluride (CdTe) nanostructures by means of RF magnetron sputtering followed by low-energy ion implantation and post-thermal treatment. We have thoroughly studied the structural, optical, and morphological properties of these nanostructures. The effects of nitrogen ion bombardment on the structural parameters of CdTe nanostructures such as crystal size, microstrain, and dislocation density have been examined. From x-ray diffractometer (XRD) analysis it could be deduced that N+ ion fluence and annealing treatment helps to form (3 0 0) orientation in the crystalline structure of cadmium-telluride films. Fluctuations in optical properties like the optical band gap and absorption coefficient as a function of N+ ion fluences have been observed. The annealing of the sample irradiated by a dose of 1018 ions cm-2 has led to great enhancement in the optical absorption over a wide range of wavelengths with a thickness of 250 nm. The enhanced absorption is significantly higher than the observed value in the original CdTe layer with a thickness of 3 μm. Surface properties such as structure, grain size and roughness are noticeably affected by varying the nitrogen fluences. It is speculated that nitrogen bombardment and post-annealing treatment results in a smaller optical band gap, which in turn leads to higher absorption. Nitrogen bombardment is found to be a promising method to increase efficiency of thin film solar cells.

  7. Heavy-ion induced desorption yields of cryogenic surfaces bombarded with 4.2 MeV/u lead ions

    CERN Document Server

    Mahner, E; Evans, L; Kollmus, H; Küchler, D; Scrivens, R; Severin, D; Wengenroth, M; CERN. Geneva. ATS Department

    2011-01-01

    The ion-induced desorption experiment, installed in the CERN Heavy-Ion Accelerator LINAC 3, has been used to study the dynamic outgassing of cryogenic surfaces. Two different targets, bare and goldcoated copper, were bombarded under perpendicular impact with 4.2 MeV/u Pb54+ ions. Partial pressure rises of H2, CH4, CO, and CO2 and effective desorption yields were measured at 300, 77, and 6.3 K using single shot and continuous ion bombardment techniques. We find that the heavy-ion-induced desorption yield is temperature dependent and investigate the influence of CO gas cryosorbed at 6.3 K. The gain in desorption yield reduction at cryogenic temperature vanishes after several monolayers of CO are cryosorbed on both targets. In this paper we describe the new cryogenic target assembly, the temperature-dependent pressure rise, desorption yield, and gas adsorption measurements.

  8. Ion-bombardment induced morphology change of device related SiGe multilayer heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Hofer, C., E-mail: Christian.Hofer@unileoben.ac.at [Institute of Physics, Montanuniversitaet Leoben, Franz Josef Str. 18, A-8700 Leoben (Austria); Teichert, C., E-mail: Christian.Teichert@unileoben.ac.at [Institute of Physics, Montanuniversitaet Leoben, Franz Josef Str. 18, A-8700 Leoben (Austria); Oehme, M.; Werner, J.; Lyutovich, K.; Kasper, E. [Institut fuer Halbleitertechnik, Universitaet Stuttgart, Pfaffenwaldring 47, D-70569 Stuttgart (Germany)

    2009-10-15

    Ion assisted molecular beam epitaxy bears the potential to tune morphological and structural parameters of semiconductor heterolayers for opto- and nanoelectronic applications. The morphology evolution and the degree of relaxation are influenced by the ion beam parameters and the strain of the heteroepitaxial film. In this work, the morphology of silicon germanium (SiGe) layers due to Si{sup +}-ion beam treatment during growth is investigated by atomic force microscopy (AFM) as a function of ion energy and ion flux density. Ion energies range from 100 eV to 1000 eV. The AFM measurements are used to determine the roughness distribution across the wafers. A regular pattern of SiGe crystallites is found, where the damage due to low ion energy Si{sup +}-ion bombardment is medium and the degree of relaxation, determined by Raman spectroscopy, is below 25%.

  9. Cosmic ion bombardment of the icy moons of Jupiter

    Energy Technology Data Exchange (ETDEWEB)

    Strazzulla, G., E-mail: gianni@oact.inaf.i [INAF-Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania (Italy)

    2011-05-01

    A large number of experiments have been performed in many laboratories in the world with the aim to investigate the physico-chemical effects induced by fast ions irradiating astrophysical relevant materials. The laboratory in Catania (Italy) has given a contribution to some experimental works. In this paper I review the results of two class of experiments performed by the Catania group, namely implantation of reactive (H{sup +}, C{sup +}, N{sup +}, O{sup +} and S{sup +}) ions in ices and the ion irradiation induced synthesis of molecules at the interface between water ice and carbonaceous or sulfurous solid materials. The results, discussed in the light of some questions concerning the surfaces of the Galilean moons, contribute to understand whether minor molecular species (CO{sub 2}, SO{sub 2}, H{sub 2}SO{sub 4}, etc.) observed on those objects are endogenic i.e. native from the satellite or are produced by exogenic processes, such as ion implantation. The results indicate that: - C-ion implantation is not the dominant formation mechanism of CO{sub 2} on Europa, Ganimede and Callisto. - Implantation of sulfur ions into water ice produces hydrated sulfuric acid with high efficiency such to give a very important contribution to the sulfur cycle on the surface of Europa and other satellites. - Implantation of protons into carbon dioxide produces some species containing the projectile (H{sub 2}CO{sub 3}, and O-H in poly-water). - Implantation of protons into sulfur dioxide produces SO{sub 3}, polymers, and O{sub 3} but not H-S bonds. - Water ice has been deposited on refractory carbonaceous materials: a general finding is the formation of a noteworthy quantity of CO{sub 2}. We suggest that this is the primary mechanism to explain the presence of carbon dioxide on the surfaces of the Galilean satellites. -Water ice has been deposited on refractory sulfurous materials originating from SO{sub 2} or H{sub 2}S irradiation. No evidence for an efficient synthesis of SO{sub 2

  10. Freestanding single-crystalline magnetic structures fabricated by ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Schoenherr, P.; Bischof, A.; Boehm, B.; Eib, P.; Grimm, S.; Gross, L.; Allenspach, R., E-mail: ral@zurich.ibm.com [IBM Research – Zurich, 8803 Rüschlikon (Switzerland); Alvarado, S. F. [Department of Materials, ETH Zürich, 8093 Zürich (Switzerland)

    2015-01-19

    Starting from an ultrathin Fe film grown epitaxially on top of a GaAs(001) substrate, we show that freestanding structures can be created by ion-beam treatment. These structures are single-crystalline blisters and only a few nanometers thick. Anisotropic stress in the rim of a blister induces magnetic domain states magnetized in the direction normal to the blister edge. Experimental evidence is provided that the lateral size can be confined by starting from a nanostructured template.

  11. Angular distribution of sputtered atoms induced by low-energy heavy ion bombardment

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lai; ZHANG Zhu-Lin

    2004-01-01

    The sputtering yield angular distributions have been calculated based on the ion energy dependence of total sputtering yields for Ni and Motargets bombarded by low-energy Hg+ ion. The calculated curves show excellent agreement with the corresponding Wehner's experimental results of sputtering yield angular distribution. The fact clearly demonstrated the intrinsic relation between the ion energy dependence of total sputtering yields and the sputtering yield angular distribution. This intrinsic relation had been ignored in Yamamura's papers (1981,1982) due to some obvious mistakes.

  12. Computer simulation of chemical erosion of graphite due to hydrogen ion bombardment

    CERN Document Server

    Liang, J H; Roth, J; Eckstein, W

    2003-01-01

    Chemical erosion of graphite due to hydrogen ion bombardment has been investigated theoretically by applying a model of chemical erosion to the TRIDYN code. The model involves the formation of methane at the end of the ion track as well as the kinetic emission of hydrocarbons from the target surface. Model calculations were performed for ion energies ranging from 10 to 1000 eV and at target temperatures ranging from 300 to 900 K. Good agreement between calculated and measured erosion yields is obtained.

  13. Electronic structure of nitinol surfaces oxidized by low-energy ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Petravic, M., E-mail: mpetravic@phy.uniri.hr; Varasanec, M.; Peter, R.; Kavre, I. [Department of Physics and Center for Micro and Nano Sciences and Technologies, University of Rijeka, 51000 Rijeka (Croatia); Metikos-Hukovic, M. [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, 10000 Zagreb (Croatia); Yang, Y.-W. [National Synchrotron Radiation Research Center, Hsinchu 30077, Taiwan (China)

    2014-06-28

    We have studied the electronic structure of nitinol exposed to low-energy oxygen-ion bombardment, using x-ray photoemission spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. XPS spectra reveal a gradual transformation of nitinol surfaces into TiO{sub 2} with increased dose of implanted oxygen. No oxidation of Ni atoms has been detected. NEXAFS spectra around O K-edge and Ti L{sub 2,3}-edge, reflecting the element-specific partial density of empty electronic states, exhibit features, which can be attributed to the creation of molecular orbitals, crystal field splitting, and the absence of long-range order, characteristic of the amorphous TiO{sub 2}. Based on these results, we discuss the oxidation kinetics of nitinol under low-energy oxygen-ion bombardment.

  14. Electronic structure of nitinol surfaces oxidized by low-energy ion bombardment

    Science.gov (United States)

    Petravic, M.; Varasanec, M.; Peter, R.; Kavre, I.; Metikos-Hukovic, M.; Yang, Y.-W.

    2014-06-01

    We have studied the electronic structure of nitinol exposed to low-energy oxygen-ion bombardment, using x-ray photoemission spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. XPS spectra reveal a gradual transformation of nitinol surfaces into TiO2 with increased dose of implanted oxygen. No oxidation of Ni atoms has been detected. NEXAFS spectra around O K-edge and Ti L2,3-edge, reflecting the element-specific partial density of empty electronic states, exhibit features, which can be attributed to the creation of molecular orbitals, crystal field splitting, and the absence of long-range order, characteristic of the amorphous TiO2. Based on these results, we discuss the oxidation kinetics of nitinol under low-energy oxygen-ion bombardment.

  15. The influences of plasma ion bombarded on crystallization, electrical and mechanical properties of Zn-In-Sn-O films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, K.J. [Instrument Center, Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Materials Science and Engineering, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Hung, F.Y., E-mail: fyhung@mail.ncku.edu.tw [Institute of Nanotechnology and Microsystems Engineering, Center for Micro/Nano Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Materials Science and Engineering, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Chang, S.J. [Institute of Microelectronics and Department of Electrical Engineering, Center for Micro/Nano Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Liao, J.D.; Weng, C.C. [Department of Materials Science and Engineering, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Hu, Z.S. [Institute of Microelectronics and Department of Electrical Engineering, Center for Micro/Nano Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2011-11-15

    The quality of co-sputtering derived Zn-In-Sn-O (ZITO) film was adjusted by different gas (oxygen and argon) induced plasma ions bombarding (PIB) treatment. The result showed that the film conductivity could be improved after plasma bombardment. The increment of oxygen vacancies and plasma bombard-induced thermal energy were main reasons. Notably, the efficiency of Ar plasma bombarded for improved conductivity not only was better but also had a smoother surface morphology. Due to Ar ions will not react with metal atoms to form oxide and possessed a higher momentum. In addition, the O-rich layer on the ultra-surface not only was removed but also enhanced film reliability by plasma bombarded that could enhance the performance of optoelectronic devices.

  16. Erosion of thin carbon layer on metal surface by hydrogen ion bombardment at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, Hirotaka, Morita, Kenji, Horino, Yuji, Itoh, Noriaki

    1985-10-01

    In this letter, we report experimental results on the erosion of thin carbon layers segregated on nickel surfaces caused by hydrogen ion bombardements at elevated temperatures. The erosion yield of the segregated carbon layers at temperatures of around 900 K was found to depend on their thickness and for the layers with a thicknes less than 20 A the yield near the 900 K was found to be nearly the same as the physical sputtering yield. (orig./RK).

  17. Irradiation damage simulation of Zircaloy-4 using argon ions bombardment

    Institute of Scientific and Technical Information of China (English)

    Dequan Peng; Xinde Bai; Feng Pan

    2008-01-01

    To simulate irradiation damage, argon ion was implanted in the Zircaloy-4 with the fluence ranging from 1×1016 to 1×1017 cm-2, using accelerating implanter at an extraction voltage of 190 kV and liquid nitrogen temperature. Then the influence of argon ion implantation on the aqueous corrosion behavior of Zircaloy-4 was studied. The valence states of elements in the surface layer of the samples wcrc analyzed using X-ray photoelectron spectroscopy (XPS). Transmission clcctron microscopy (TEM) was used to examine the microstructure of the argon-implanted samples. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted Zircaloy-4 in 1 mol/L H2SO4 solution. It is found that there appear bubbles on the surface of the samples when the argon flucncc is 1×1016 cm-2. The microstructure of argon-implanted samples changes from amor-phous to partial amorphous, then to polycrystallinc, and again to amorphous. The corrosion resistance of implanted samples linearly declines with the increase of flucnce approximately, which is attributed to the linear increase of the irradiation damage.

  18. ISS observations of aluminium surfaces under hydrogen ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Sagara, A.; Kamada, K.; Higashida, Y.

    1984-12-01

    The shadowing effect of ISS was applied to observe the surface behavior of H atoms implanted with 500 eV/atom on a high-purity Al sample. This study confirmed that this technique is powerful to observe the retention kinetics of H atoms especially on the topmost material surface with simultaneous analysis for surface contaminants such as oxygen during irradiation with hydrogen ions. The result obtained from the initially cleaned surface showed a remarkable increase in the H retention with increasing fluence of H/sub 2//sup +/ up to about 10/sup 18/ H/cm/sup 2/ at room temperature, depending on the fluence of predamage given by He/sup +/ ions, but showed no increase in the retention at the temperatures above 100/sup 0/C. Therefore, because Al is a metal well known to be passive for chemisorption of H/sub 2/ molecules and H atoms, it was concluded that the observed H retention originates from the traps produced by radiation damage. The activation energy for thermal desorption of the trapped H atoms was estimated to be 1.1 +- 0.4 eV by ISS measurements. The oxygen-covered surface showed a rapid increase in the retention at fluence of less than 10/sup 17/ H/cm/sup 2/. (orig.).

  19. Iss observations of aluminum surfaces under hydrogen ion bombardment

    Science.gov (United States)

    Sagara, A.; Kamada, K.; Higashida, Y.

    1984-12-01

    The shadowing effect of ISS was applied to observe the surface behavior of H atoms implanted with 500 eV/atom on a high-purity A1 sample. This study confirmed that this technique is powerful to observe the retention kinetics of H atoms especially on the topmost material surface with simultaneous analysis for surface contaminants such as oxygen during irradiation with hydrogen ions. The result obtained from the initially cleaned surface showed a remarkable increase in the H retention with increasing fluence of H2+ up to about 1018 H/cm2 at room temperature, depending on the fluence of predamage given by He+ ions, but showed no increase in the retention at the temperatures above 100 ° C. Therefore, because Al is a metal well known to be passive for chemisorption of H2 molecules and H atoms, it was concluded that the observed H retention originates from the traps produced by radiation damage. The activation energy for thermal desorption of the trapped H atoms was estimated to be 1.1±0.4 eV by ISS measurements. The oxygen-covered surface showed a rapid increase in the retention at fluence of less than 1017 H/cm2.

  20. ISS observations of aluminium surfaces under hydrogen ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Sagara, A.; Kamada, K. (Nagoya Univ. (Japan). Inst. of Plasma Physics); Higashida, Y. (Seiun Senior High School (Japan))

    1984-12-01

    The shadowing effect of ISS was applied to observe the surface behavior of H atoms implanted with 500 eV/atom on a high-purity Al sample. This study confirmed that this technique is powerful to observe the retention kinetics of H atoms especially on the topmost material surface with simultaneous analysis for surface contaminants such as oxygen during irradiation with hydrogen ions. The result obtained from the initially cleaned surface showed a remarkable increase in the H retention with increasing fluence of H/sub 2//sup +/ up to about 10/sup 18/ H/cm/sup 2/ at room temperature, depending on the fluence of predamage given by He/sup +/ ions, but showed no increase in the retention at the temperatures above 100/sup 0/C. Therefore, because Al is a metal well known to be passive for chemisorption of H/sub 2/ molecules and H atoms, it was concluded that the observed H retention originates from the traps produced by radiation damage. The activation energy for thermal desorption of the trapped H atoms was estimated to be 1.1 +- 0.4 eV by ISS measurements. The oxygen-covered surface showed a rapid increase in the retention at fluence of less than 10/sup 17/ H/cm/sup 2/.

  1. Analysis of cardiac tissue by gold cluster ion bombardment

    Science.gov (United States)

    Aranyosiova, M.; Chorvatova, A.; Chorvat, D.; Biro, Cs.; Velic, D.

    2006-07-01

    Specific molecules in cardiac tissue of spontaneously hypertensive rats are studied by using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The investigation determines phospholipids, cholesterol, fatty acids and their fragments in the cardiac tissue, with special focus on cardiolipin. Cardiolipin is a unique phospholipid typical for cardiomyocyte mitochondrial membrane and its decrease is involved in pathologic conditions. In the positive polarity, the fragments of phosphatydilcholine are observed in the mass region of 700-850 u. Peaks over mass 1400 u correspond to intact and cationized molecules of cardiolipin. In animal tissue, cardiolipin contains of almost exclusively 18 carbon fatty acids, mostly linoleic acid. Linoleic acid at 279 u, other fatty acids, and phosphatidylglycerol fragments, as precursors of cardiolipin synthesis, are identified in the negative polarity. These data demonstrate that SIMS technique along with Au 3+ cluster primary ion beam is a good tool for detection of higher mass biomolecules providing approximately 10 times higher yield in comparison with Au +.

  2. Ion-bombardment-enhanced diffusion during the growth of sputtered superlattice thin films

    Energy Technology Data Exchange (ETDEWEB)

    Eltoukhy, A.H.; Greene, J.E.

    1978-08-15

    A technique is presented for determining the enhancement in solid-state diffusion caused by low-energy ion bombardment. In this technique, superlattice films are grown under varying conditions of ion bombardment and the amplitude of the resulting composition modulation wave is determined by analyzing x-ray diffraction satellite peaks surrounding the central Bragg peaks. The amplitude is in turn related to the enhanced diffusion coefficient D* (x) which may be expressed as D*/sub 0/ exp(-x/delta) where delta is a characteristic diffusion length of the ion-bombardment-produced defects. This approach was confirmed experimentally using InSb/GaSb superlattice structures grown by multitarget sputtering, each sample having equilayer thicknesses between 12 and 30 A. D* was found to increase as the sputtering pressure was decreased. Measured values of D* averaged over the enhanced diffusion region were on the order of 10/sup -17/ cm/sup 2//sec compared to a thermal interdiffusion coefficient of approximately 10/sup -22/ cm/sup 2//sec at the film growth temperature of 250 /sup 0/C.

  3. Effect of Ion Bombardment on the Growth and Properties of Hydrogenated Amorphous Silicon-Germanium Alloys

    Science.gov (United States)

    Perrin, Jérôme; Takeda, Yoshihiko; Hirano, Naoto; Matsuura, Hideharu; Matsuda, Akihisa

    1989-01-01

    We report a systematic investigation of the effect of ion bombardment during the growth of amorphous silicon-germanium alloy films from silane and germane rf-glow discharge. Independent control of the plasma and the ion flux and energy is obtained by using a triode configuration. The ion contribution to the total deposition rate can reach 20% on negatively biased substrates. Although the Si and Ge composition of the film does not depend on the ion flux and energy, the optical, structural and electronic properties are drastically modified at low deposition temperatures when the maximum ion energy increases up to 50 eV, and remain constant above 50 eV. For a Ge atomic concentration of 37% and a temperature of 135°C, the optical gap decreases from 1.67 to 1.45 eV. This is correlated with a modification of hydrogen bonding configurations. Silicon dihydride sites disappear and preferential attachment of hydrogen to silicon is reduced in favour of germanium. Moreover the photoconductivity increases which shows that ion bombardment is a key parameter to optimize the quality of low band gap amorphous silicon-germanium alloys.

  4. Investigation of energy thresholds of atomic and cluster sputtering of some elements under ion bombardment

    CERN Document Server

    Atabaev, B G; Lifanova, L F

    2002-01-01

    Threshold energies of sputtering of negative cluster ions from the Si(111) surface were measured at bombardment by Cs sup + , Rb sup + , and Na sup + ions with energy of 0.1-3.0 keV. These results are compared with the calculations of the similar thresholds by Bohdansky etc. formulas (3) for clusters Si sub n sup - and Cu sub n sup - with n=(1-5) and also for B, C, Al, Si, Fe, Cu atoms. Threshold energies of sputtering for the above elements were also estimated using the data from (5). Satisfactory agreement between the experimental and theoretical results was obtained. (author)

  5. Effect of low energy ion bombardment on structure and photoluminescence characterization of Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Chenggang; Yu, Tao; Wu, Zaofeng; Wu, Xuemei [Department of Physics, Soochow University, Soochow 215006 (China); Zhuge, Lanjian, E-mail: ljzhuge@suda.edu.cn [Analysis and Testing Center, Soochow University, Soochow 215006 (China)

    2012-12-01

    Al-doped zinc oxide (AZO) films are prepared by dual ion-beam assisted sputter deposition at room temperature. An assisting argon ion beam (ion energy E{sub i} = 0-300 eV) directly bombards the substrate surface to modify the properties of the AZO films. The effects of assisting ion beam energy on the characteristics of AZO films were investigated based on transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and photoluminescence measurement. With increasing assisting ion beam bombardment, the crystalline quality of the AZO films was improved and the oxygen vacancies were increased observably. Two red emissions originating from the oxygen vacancies in the films appear at 1.71 and 1.64 eV. This study suggests that wide-band-gap materials could act as effective visible light emitters and ion beam bombardment provides a simple route to synthesize such materials. - Highlights: Black-Right-Pointing-Pointer Al-doped ZnO (AZO) thin films were prepared by dual ion-beam sputter deposition. Black-Right-Pointing-Pointer By assisting-ion beam bombardment, AZO films have a better c-axis orientation. Black-Right-Pointing-Pointer The crystalline quality of AZO films was improved by assisting-ion beam bombardment. Black-Right-Pointing-Pointer Two red emissions originate from the oxygen vacancies in the films.

  6. Surface Erosion of GaN Bombarded by Highly Charged 208Pbq+-Ions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-Qing; ZHANG Chong-Hong; YANG Yi-Tao; YAO Cun-Feng; LI Bing-Sheng; JIN Yun-Fan; SUN You-Mei; SONG Shu-Jian

    2008-01-01

    Surface change of gallium nitride specimens after bombardment by highly charged Pbq+-ions (q=25, 35) at room temperature is studied by means of atomic force microscopy. The experimental results reveal that the surface of GaN specimens is significantly etched and erased. An unambiguous step-up is observed. The erosion depth not only strongly depends on the charge state of ions, but also is related to the incident angle of Pbq+ -ions and the ion dose. The erosion depth of the specimens in 60°incidence (tilted incidence) is significantly deeper than that of the normal incidence. The erosion behaviour of specimens has little dependence on the kinetic energy of ion (E,k=360, 700keV). On the other hand, surface roughness of the irradiated area is obviously decreased due to erosion compared with the un-irradiated area. A flat terrace is formed.

  7. The effect of CH4/H2 ratio on the surface properties of HDPE treated by CHx ion beam bombardment

    Science.gov (United States)

    Ding, Wanyu; Guo, Yuanyuan; Ju, Dongying; Sato, Susumu; Tsunoda, Teruo

    2016-06-01

    The surface of high density polyethylene (HDPE) substrate was bombarded by the CHx group ion beam, which was generated by the mixture of CH4/H2. Varying the CH4/H2 ratio, HDPE surfaces with different chemical bond structures and properties were obtained. Raman and XPS results show that sp2 and sp3 bond structures are formed at HDPE surface bombarded by CHx group ions. The sp3 bond fraction at bombarded HDPE surface depends on the H2 ratio in CH4/H2 mixture, because the H ion/atom/molecule can improve the growth of sp3 bond structure. For HDPE surface bombarded by CH4/H2 = 50/50, sp3 bond fraction reaches the maximum of 30.5%, the surface roughness decreases to 17.04 nm, and the static contact angle of polar H2O molecule increased to 140.2∘.

  8. Bombardment induced ion transport - part IV: ionic conductivity of ultra-thin polyelectrolyte multilayer films.

    Science.gov (United States)

    Wesp, Veronika; Hermann, Matthias; Schäfer, Martin; Hühn, Jonas; Parak, Wolfgang J; Weitzel, Karl-Michael

    2016-02-14

    The dependence of the ionic conductance of ultra-thin polyelectrolyte multilayer (PEM) films on the temperature and the number of bilayers has been investigated by the recently developed low energy bombardment induced ion transport (BIIT) method. To this end multilayers of alternating poly(sodium 4-styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) layers were deposited on a metal electrode and subsequently bombarded by a low energy potassium ion beam. Ions are transported through the film according to the laws of electro-diffusion towards a grounded backside electrode. They are neutralized at the interface between the polymer film and the metal electrode. The detected neutralization current scales linearly with the acceleration potential of the ion beam indicating Ohmic behavior for the (PAH/PSS)x multilayer, where x denotes the number of bilayers. The conductance exhibits a non-monotonic dependence on the number of bilayers, x. For 2 ≤ x ≤ 8 the conductance increases non-linearly with the number of bilayers. For x ≥ 8 the conductance decreases with increasing number of bilayers. The variation of the conductance is rationalized by a model accounting for the structure dependence of the conductivity. The thinnest sample for which the conductance has been measured is the single bilayer reflecting properties dominated by the interface. The activation energy for the ion transport is 0.49 eV.

  9. Effect of bombardment with iron ions on the evolution of helium, hydrogen, and deuterium blisters in silicon

    Science.gov (United States)

    Reutov, V. F.; Dmitriev, S. N.; Sokhatskii, A. S.; Zaluzhnyi, A. G.

    2017-02-01

    The effect of bombardment with iron ions on the evolution of gas porosity in silicon single crystals has been studied. Gas porosity has been produced by implantation hydrogen, deuterium, and helium ions with energies of 17, 12.5, and 20 keV, respectively, in identical doses of 1 × 1017 cm-2 at room temperature. For such energy of bombarding ions, the ion doping profiles have been formed at the same distance from the irradiated surface of the sample. Then, the samples have been bombarded with iron Fe10+ ions with energy of 150 keV in a dose of 5.9 × 1014 cm-2. Then 30-min isochoric annealing has been carried out with an interval of 50°C in the temperature range of 250-900°C. The samples have been analyzed using optical and electron microscopes. An extremely strong synergetic effect of sequential bombardment of silicon single crystals with gas ions and iron ions at room temperature on the nucleation and growth of gas porosity during postradiation annealing has been observed. For example, it has been shown that the amorphous layer formed in silicon by additional bombardment with iron ions stimulates the evolution of helium blisters, slightly retards the evolution of hydrogen blisters, and completely suppresses the evolution of deuterium blisters. The results of experiments do not provide an adequate explanation of the reason for this difference; additional targeted experiments are required.

  10. Residual stress in nano-structured stainless steel (AISI 316L) prompted by Xe+ ion bombardment at different impinging angles

    Science.gov (United States)

    Cucatti, S.; Droppa, R.; Figueroa, C. A.; Klaus, M.; Genzel, Ch.; Alvarez, F.

    2016-10-01

    The effect of low energy (316L steel) is reported. The results take into account the influence of the ion incident angle maintaining constant all other bombarding parameters (i.e., ion energy and current density, temperature, and doses). The bombarded surface topography shows that ions prompt the formation of nanometric regular patterns on the surface crystalline grains and stressing the structure. The paper focalizes on the study of the surface residual stress state stemming from the ion bombardment studied by means of the "sin2 ψ" and "Universal Plot" methods. The analysis shows the absence of shear stress in the affected material region and the presence of compressive in-plane residual biaxial stress (˜200 MPa) expanding up to ˜1 μm depth for all the studied samples. Samples under oblique bombardment present higher compressive stress values in the direction of the projected ion beam on the bombarded surface. The absolute value of the biaxial surface stress difference (σ11-σ22) increases on ion impinging angles, a phenomenon associated with the momentum transfer by the ions. The highest stress level was measured for ion impinging angles of 45° ( σ 11 = -380 ± 10 MPa and σ 22 = -320 ± 10 MPa). The different stresses obtained in the studied samples do not affect significantly the formation of characteristic surface patterns.

  11. Emission of neutral molecules from ion-bombarded thiol self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Postawa, Z. E-mail: zp@castor.if.uj.edu.pl; Meserole, C.A.; Cyganik, P.; Szymonska, J.; Winograd, N

    2001-08-01

    We have investigated ion-stimulated desorption of neutral molecules emitted from 8 keV Ar{sup +} ion-bombarded self-assembled monolayers (SAMs) of phenethyl mercaptan (PEM) C{sub 6}H{sub 5}CH{sub 2}CH{sub 2}-SH and 2-(4{sup '}-methyl-biphenyl-4yl)-ethanethiol (BP2) CH{sub 3}C{sub 6}H{sub 4}C{sub 6}H{sub 4}CH{sub 2}CH{sub 2}-SH deposited on Au(1 1 1) substrate. Neutral molecules were detected by laser postionization mass spectrometry. Only molecular fragments were detected from ion-bombarded systems. The mass spectra obtained for sputtered and gas phase fragments indicate that molecules recorded during ion bombardment were indeed emitted from the surface and were not the result of photofragmentation induced by the ionizing laser beam. From experimentally obtained time-of-flight (TOF) distributions, it was determined that the majority of desorbed neutral molecules leave the surface with very low translational energies. As the sample temperature is reduced, the distributions become broader and shift to longer flight times. The shift is more pronounced for molecules from BP2 and increases with the mass of the recorded molecular fragment. We postulate that the emission of molecules is initiated by processes which gently break molecular bonds (e.g., chemical reactions, secondary electrons). The formed fragments are loosely bound to the surface and can be removed by evaporation. At the investigated temperature range (170-350 K), the observed emission delay is attributed to the time required for the molecule to evaporate from the surface and is not influenced by the bond breaking rate.

  12. Absorption of hydrogen in vanadium, enhanced by ion bombardment; Ionenbeschussunterstuetzte Absorption des Wasserstoffs in Vanadium

    Energy Technology Data Exchange (ETDEWEB)

    Paulus, H.; Lammers, M. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany); Mueller, K.H. [Inst. fuer Technologie- und Wissenstransfer, Soest (Germany)]|[Paderborn Univ. (Gesamthochschule), Soest (Germany). Fachbereich 16 - Elektrische Energietechnik; Kiss, G.; Kemeny, Z. [Technical Univ. Budapest (Hungary)

    1998-12-31

    Prior to hydrogen implantation into vanadium, the vanadium specimen usually is exposed to an activation process and is then heated at 1 atm hydrogen to temperatures between 500 and 600 C, subsequently cooled down in several steps. Within this temperature range, hydrogen solubility increases with declining temperature. A decisive factor determining hydrogen absorption is the fact that at temperatures above 250 C, oxygen desorbs from the material surface and thus no longer inhibits hydrogen absorption. Therefore a different approach was chosen for the experiments reported: Hydrogen absorption under UHV conditions at room temperature. After the usual activation process, the vanadium surface was cleaned by 5 keV Ar{sup +} ion bombardment. Thus oxygen absorption at the specimen surface (and new reactions with oxygen from the remaining gas) could be avoided, or removed. By means of thermal desorption mass spectrometry (TDMS), hydrogen absorption as a function of argon ion dose was analysed. TDMS measurements performed for specimens treated by ion bombardment prior to H{sup 2} exposure showed two H{sup 2} desorption peaks, in contrast to the profiles measured with specimens not exposed to ion bombardment. It is assumed that the ion bombardment disturbs the crystal structure so that further sites for hydrogen absorption are produced. (orig./CB) [Deutsch] Bei der Beladung von Vandium mit Wasserstoff wird ueblicherweise die Probe nach einer Aktivierungsprozedur bei 1 atm Wasserstoff auf Temperaturen im Bereich von 500 bis 600 C hochgeheizt und danach schrittweise abgekuehlt. In diesem Temperaturbereich nimmt die Wasserstoffloeslichkeit mit abnehmender Temperatur zu. Entscheidend fuer die Beladung ist aber auch die Tatsache, dass bei Temperaturen groesser 250 C Sauerstoff von der Oberflaeche desorbiert und dadurch die Absorption von Wasserstoff nicht mehr blockieren kann. Im Rahmen der hier beschriebenen Untersuchungen sollte die Wasserstoffbeladung unter UHV-Bedingungen bei

  13. Microstructure of titanium nitride thin films controlled by ion bombardment in a magnetron-sputtering device

    Energy Technology Data Exchange (ETDEWEB)

    Cerny, R. (Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni); Kuzel, R. Jr. (Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni); Valvoda, V. (Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni); Kadlec, S. (Czechoslovak Academy of Sciences, Prague (Czechoslovakia). Inst. of Physics); Musil, J. (Czechoslovak Academy of Sciences, Prague (Czechoslovakia). Inst. of Physics)

    1994-05-01

    The structure of titanium nitride thin films deposited by unbalanced magnetron sputtering on high chromium steel substrates was studied by X-ray diffraction. In order to characterize relations between the microstructure of sputtered TiN films and the deposition conditions, the parameter E[sub p] was introduced as the average energy transmitted from bombarding particles (ions, electrons, neutrals, photons) to one condensing particle of the film. A transition from a porous to a compact microstructure was found with increasing E[sub p]. The possible inhomogeneity of titanium nitride films is discussed. (orig.)

  14. Biological Effects of Low Energy Ar+ Ion Bombardment on Silkworm Eggs: a Novel Animal Model

    Science.gov (United States)

    Xu, Jiaping; Wu, Yuejin; Liu, Xuelan; Yuan, Hang; Yu, Zengliang

    2009-06-01

    In this study, we found for the first time that silkworm eggs were able to survive in vacuum for a long period of time. Subsequently, low energy Ar+ ions with different energies and fluences were used to bombard silkworm eggs so as to explore the resulting biological effects. Results showed that (i) the exposure of silkworm eggs to vacuum within 10 min did not cause significant impact on the hatching rates, while the irradiation of silkworm eggs by Ar+ ions of 25 keV or 30 keV with fluences ranging from 2.6×2.6 × 1015 ion/cm2 to 8×2.6 × 1015 ion/cm2 caused a significant impact on the hatching rates, and the hatching rates decreased with the increase in the fluence and energy level; (ii) the irradiation of silkworm eggs by Ar+ ions of 30 keV with a fluence of 8×2.6 × 1015 ion/cm2 or 9×2.6 × 1015 ion/cm2 resulted in a noticeable etching on the egg shell surface which could be observed by a scanning electron microscope; and (iii) the irradiation of silkworm eggs by Ar+ ions of 30 keV with a fluence of 9×2.6 × 1015 ion/cm2 generated several mutant phenotypes which were observed in the 5th instar silkworms and a moth.

  15. Biological Effects of Low Energy Ar+ Ion Bombardment on Silkworm Eggs: a Novel Animal Model

    Institute of Scientific and Technical Information of China (English)

    XU Jiaping; WU Yuejin; LIU Xuelan; YUAN Hang; YU Zengliang

    2009-01-01

    In this study, we found for the first time that silkworm eggs were able to survive in vacuum for a long period of time. Subsequently, low energy Ar+ ions with different energies and fluences were used to bombard silkworm eggs so as to explore the resulting biological effects. Results showed that (i) the exposure of silkworm eggs to vacuum within 10 min did not cause significant impact on the hatching rates, while the irradiation of silkworm eggs by Ar+ ions of 25 keY or 30 keV with fluences ranging from 2.6×2.6 × 1015 ion/cm2 to 8×2.6 × 1015ion/cm2 caused a significant impact on the hatching rates, and the hatching rates decreased with the increase in the fluence and energy level; (ii) the irradiation of silkworm eggs by Ar+ ions of 30 keV with a fluence of 8×2.6 × 1015 ion/cm2 or 9×2.6×1015 ion/cm2 resulted in a noticeable etching on the egg shell surface which could be observed by a scanning electron microscope; and (iii) the irradiation of silkworm eggs by Ar+ ions of 30 keV with a fluence of 9×2.6 × 1015 ion/cm2 generated several mutant phenotypes which were observed in the 5th instar silkworms and a moth.

  16. Angular and energy dependence of ion bombardment of Mo/Si multilayers

    DEFF Research Database (Denmark)

    Voorma, H.J.; Louis, E.; Bijkerk, F.;

    1997-01-01

    The process of ion bombardment is investigated for the fabrication of Mo/Si multilayer x-ray mirrors using e-beam evaporation. The ion treatment is applied immediately after deposition of each of the Si layers to smoothen the layers by removing an additional thickness of the Si layer. In this study...... the parameters of Kr+ ion bombardment have been optimized within the energy range 300 eV-2 keV and an angular range between 20 degrees and 50 degrees. The optical performance of the Mo/Si multilayers is determined by absolute measurements of the near-normal-incidence reflectivity at 14.4 nm wavelength...... are found to be 2 keV at 50 degrees angle of incidence with respect to the surface. These settings result in 47% reflectivity at 85 degrees (lambda = 14.4 nm) for a 16-period Mo/Si multilayer mirror, corresponding to an interface roughness of 0.21 nm rms. Analysis shows that the interface roughness...

  17. A liquid-like model for the morphology evolution of ion bombarded thin films

    Energy Technology Data Exchange (ETDEWEB)

    Repetto, L., E-mail: luca.repetto@unige.it [Department of Physics and Nanomed Labs, Università di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Lo Savio, R. [Department of Physics and Nanomed Labs, Università di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Šetina Batič, B. [Inštitut Za Kovinske Materiale in Tehnologije, Lepi pot 11, 1000 Ljubljana (Slovenia); Firpo, G.; Angeli, E.; Valbusa, U. [Department of Physics and Nanomed Labs, Università di Genova, Via Dodecaneso 33, 16146 Genova (Italy)

    2015-07-01

    Thin solid films exposed to ion irradiation exhibit a peculiar evolution that can differ substantially from what is observed for bulk samples. The phenomenology of the patterns that self-organize on the substrate is very rich, with morphologies that display several degrees of order upon the modification of initial film characteristics and irradiation parameters. This richness paves the way for the fabrication of novel functional surfaces, but it is also an indication of the complexity of the underlying driving mechanisms. A remarkable simplification for the comprehension of these phenomena can come from the noteworthy similarity of the obtained patterns with those showing up when liquids dewet from their substrates. Here, we analyze the possibility to apply a liquid-like model to explain the morphology evolution of ion bombarded thin films for the whole phenomenology showing up in experiments. In establishing this connection between liquids and ion bombarded thin films, we propose to use also for liquids the insight gained for our system with recent experiments that stress the importance of the substrate topography for the selection of the dewetting mechanism. If confirmed, this result would lead to a reconsideration of the importance of capillary waves in spinodal dewetting, and will help to understand the low reproducibility of the related experimental results.

  18. Binary collision model for neon Auger spectra from neon ion bombardment of the aluminum surface

    Science.gov (United States)

    Pepper, S. V.

    1986-01-01

    A model is developed to account for the angle-resolved Auger spectra from neon ion bombardment of the aluminum surface recently obtained by Pepper and Aron. The neon is assumed to be excited in a single asymmetric neon-aluminum-collision and scattered back into the vacuum where it emits an Auger electron. The velocity of the Auger electron acquires a Doppler shift by virtue of the emission from a moving source. The dependence of the Auger peak shape and energy on the incident ion energy, angle of incidence and on the angle of Auger electron emission with respect to the surface is presented. Satisfactory agreement with the angle resolved experimental observations is obtained. The dependence of the angle-integrated Auger yield on the incident ion energy and angle of incidence is also obtained and shown to be in satisfactory agreement with available experimental evidence.

  19. Synergistic effects of vacuum ultraviolet radiation, ion bombardment, and heating in 193 nm photoresist roughening and degradation

    Science.gov (United States)

    Nest, D.; Graves, D. B.; Engelmann, S.; Bruce, R. L.; Weilnboeck, F.; Oehrlein, G. S.; Andes, C.; Hudson, E. A.

    2008-04-01

    The roles of ultraviolet/vacuum ultraviolet (UV/VUV) photons, Ar+ ion bombardment and heating in the roughening of 193nm photoresist have been investigated. Atomic force microscopy measurements show minimal surface roughness after UV/VUV-only or ion-only exposures at any temperature. Simultaneous UV/VUV, ion bombardment, and heating to surface temperatures of 60-100°C result in increased surface roughness, and is comparable to argon plasma-exposed samples. Ion bombardment creates a modified near-surface layer while UV/VUV radiation results in loss of carbon-oxygen bonds up to a depth of ˜100nm. Enhanced roughness is only observed in the presence of all three effects.

  20. Ion bombardment induced morphology modifications on self-organized semiconductor surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hofer, C. E-mail: christian.hofer@unileoben.ac.at; Abermann, S.; Teichert, C.; Bobek, T.; Kurz, H.; Lyutovich, K.; Kasper, E

    2004-02-01

    The successful generation of well ordered nanopatterns on III-V semiconductor surfaces by ion erosion initiated attempts to obtain similar effects on silicon surfaces. High resolution atomic-force microscopy (AFM) is used to quantify the morphological changes of self-organized silicon/germanium films on Si(0 0 1) during ion bombardment. A nanofaceted SiGe film exhibiting a checkerboard array of {l_brace}1 0 5{r_brace} faceted pyramids and pits was eroded by Ar{sup +} ions of 100-1000 eV under normal incidence. Two characteristic energy regimes have been found. For ion energies below 750 eV the pyramidal pits transform into shallow troughs before smaller craters form. At ion energies of 750 eV and above, a significant smoothening of the surface was observed, finally resulting in a vanishing of the pattern. The influence of the initial pattern and the ion energy on the morphological changes are compared for different SiGe-films. Since at low ion energies the checkerboard array of {l_brace}1 0 5{r_brace} pyramids and pits could be transferred into the silicon substrate this procedure illustrates an alternative way to nanostructure silicon surfaces by ion erosion.

  1. Molecular dynamic simulation of secondaryion ion emission from an Al sample bombarded with MeV heavy ions

    Institute of Scientific and Technical Information of China (English)

    薛建明; 今西信嗣

    2002-01-01

    Sputtering yields and kinetic energy distributions (KED) of Al atomic ions ejected from a pure aluminium sampleunder MeV silicon ion bombardment were simulated with the molecular dynamic method. Since the electronic energyloss Se is much higher than the nuclear energy loss Sn when the incident ion energy is as high as several MeV, the Seeffect was also taken into consideration in the simulation. It was found that the simulated sputtering yield fits well withthe experimental data and the electronic energy loss has a slight effect at incident ion energies higher than 4 MeV. Thesimulated secondary ion KED spectrum is a little lower in the peak energy and narrower in the peak width than thatin the experiment.

  2. The effects of argon ion bombardment on the corrosion resistance of tantalum

    Science.gov (United States)

    Ramezani, A. H.; Sari, A. H.; Shokouhy, A.

    2017-02-01

    Application of ion beam has been widely used as a surface modification method to improve surface properties. This paper investigates the effect of argon ion implantation on surface structure as well as resistance against tantalum corrosion. In this experiment, argon ions with energy of 30 keV and in doses of 1 × 1017-10 × 1017 ions/cm2 were used. The surface bombardment with inert gases mainly produces modified topography and morphology of the surface. Atomic Force Microscopy was also used to patterned the roughness variations prior to and after the implantation phase. Additionally, the corrosion investigation apparatus wear was applied to compare resistance against tantalum corrosion both before and after ion implantation. The results show that argon ion implantation has a substantial impact on increasing resistance against tantalum corrosion. After the corrosion test, scanning electron microscopy (SEM) analyzed the samples' surface morphologies. In addition, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. The purpose of this paper was to obtain the perfect condition for the formation of tantalum corrosion resistance. In order to evaluate the effect of the ion implantation on the corrosion behavior, potentiodynamic tests were performed. The results show that the corrosion resistance of the samples strongly depends on the implantation doses.

  3. The effect of crystal orientation on the behavior of a polycrystalline tungsten surface under focused Ga{sup +} ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Ran Guang, E-mail: gran@xmu.edu.cn [School of Energy Research, Xiamen University, Xiamen, Fujian 361005 (China); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Wu Shenghua [School of Energy Research, Xiamen University, Xiamen, Fujian 361005 (China); Liu Xiang; Wu Jihong [Southwestern Institute of Physics, Chengdu, Sichuan 610041 (China); Li, Ning [School of Energy Research, Xiamen University, Xiamen, Fujian 361005 (China); Zu Xiaotao [Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Wang Lumin, E-mail: lmwang@umich.edu [School of Energy Research, Xiamen University, Xiamen, Fujian 361005 (China); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer We in situ investigated the microstructure evolution during FIB bombardment. Black-Right-Pointing-Pointer The irradiation behaviors depended significantly on the crystal orientation. Black-Right-Pointing-Pointer Tungsten grain with (0 0 1) crystal orientation showed good irradiation resistance. - Abstract: The effect of crystal orientation on the behavior of a tungsten surface under a 30 keV focused Ga{sup +} ion beam with different bombardment angles has been investigated by in situ scanning electron microscopy and electron backscatter diffraction. Results indicate that the grains of tungsten with various orientations behave quite differently. Grains with a (0 0 1) direction parallel to the ion beam always maintain a much smoother surface morphology with less mass removal after ion bombardment, indicating a lower sputtering yield. The orientation dependence of surface sputtering of tungsten can be used to guide the fabrication of tungsten-based first wall component in a nuclear fusion reactor.

  4. Blazed diffraction gratings produced by ion bombardment of pre-patterned solid surfaces

    Science.gov (United States)

    Harrison, Matt P.; Bradley, R. Mark

    2017-02-01

    We propose a method of producing high quality blazed gratings and carry out simulations of it. By combining the near perfect periodicity produced by conventional lithographic methods with the tendency of ion sputtering to produce terraced topographies, this fabrication procedure could produce highly ordered, faceted surfaces on amorphous materials. Our approach differs from previous uses of ion bombardment to fabricate blazed gratings, and has the unique advantage that it could be used as the initial step in the fabrication of high efficiency multilayer-coated blazed gratings. Our numerical investigations of the relevant equations of motion demonstrate that our method produces efficient blazed gratings for a broad range of parameter values. We also develop concrete predictions regarding the optimal implementation of our proposed procedure, and show that high quality blazed gratings can emerge even if additional linear or nonlinear terms are present in the equation of motion.

  5. Diffusion enhancement due to low-energy ion bombardment during sputter etching and deposition

    Science.gov (United States)

    Eltoukhy, A. H.; Greene, J. E.

    1980-08-01

    The effects of low-energy ion bombardment on enhancing elemental diffusion rates at both heterojunction interfaces during film deposition and over the compositionally altered layer created during sputter etching alloy targets have been considered. Depth dependent enhanced interdiffusion coefficients, expressed as D*(x)=D*(0) exp(-x/Ld), where D*(0) is more than five orders of magnitude greater than thermal diffusion values, were measured in InSb/GaSb multilayer structures deposited by multitarget bias sputering. D*(0) was determined from the amplitude u of the compositional modulation in the multilayered films (layer thicknesses between 20 and 45 Å) as measured by superlattice x-ray diffraction techniques. The value of D*(0) was found to increase from 3×10-17 to 1×10-16 cm2/sec as the applied substrate bias was increased from 0 to -75 V. However even at Va=0, the diffusion coefficient was enhanced owing to an induced substrate potential with respect to the positive space-charge region in the Ar discharge. The diffusion length of Ld of the ion bombardment created defects was ˜1000 Å. Enhanced diffusion also has a significiant effect on the altered layer thickness xe and the total sputtering time te (or ion dose) required to reach steady state during ion etching of multielement targets. The effects of using an exponentially depth dependent versus a constant value of the enhanced diffusion coefficient on calculated values of xe and te in single-phase binary alloys were considered. The results show that both xe and te are considerably larger using a depth dependent D*(x), when Ld

  6. An investigation of enhanced secondary ion emission under Au(n)+ (n = 1-7) bombardment.

    Science.gov (United States)

    Nagy, G; Gelb, L D; Walker, A V

    2005-05-01

    We investigate the mechanism of the nonlinear secondary ion yield enhancement using Au(n)+ (n = 1, 2, 3, 5, 7) primary ions bombarding thin films of Irganox 1010, DL-phenylalanine and polystyrene on Si, Al, and Ag substrates. The largest differences in secondary ion yields are found using Au+, Au2+, and Au3+ primary ion beams. A smaller increase in secondary ion yield is observed using Au5+ and Au7+ primary ions. The yield enhancement is found to be larger on Si than on Al, while the ion yield is smaller using an Au+ beam on Si than on Al. Using Au(n)+ ion structures obtained from Density Functional Theory, we demonstrate that the secondary yield enhancement is not simply due to an increase in energy per area deposited into the surface (energy deposition density). Instead, based on simple mechanical arguments and molecular dynamics results from Medvedeva et al, we suggest a mechanism for nonlinear secondary ion yield enhancement wherein the action of multiple concerted Au impacts leads to efficient energy transfer to substrate atoms in the near surface region and an increase in the number of secondary ions ejected from the surface. Such concerted impacts involve one, two, or three Au atoms, which explains well the large nonlinear yield enhancements observed going from Au+ to Au2+ to Au3+ primary ions. This model is also able to explain the observed substrate effect. For an Au+ ion passing through the more open Si surface, it contacts fewer substrate atoms than in the more dense Al surface. Less energy is deposited in the Si surface region by the Au+ primary ion and the secondary ion yield will be lower for adsorbates on Si than on Al. In the case of Au(n)+ the greater density of Al leads to earlier break-up of the primary ion and a consequent reduction in energy transfer to the near-surface region when compared with Si. This results in higher secondary ion yields and yield enhancements on silicon than aluminum substrates.

  7. Photon emission produced by Kr+ ions bombardment of Cr and Cr2O3 targets

    Science.gov (United States)

    Boujlaidi, A. El; Hammoum, K.; Jadoual, L.; Jourdani, R.; Ait El Fqih, M.; Aouchiche, H.; Kaddouri, A.

    2015-01-01

    The sputter induced photon spectroscopy technique was used to study the luminescence spectra of the species sputtered from chromium powder and its oxide Cr2O3, during 5 keV Kr+ ions bombardment in vacuum better than 10-7 torr. The optical spectra recorded between 350 and 470 nm exhibit discrete lines which are attributed to neutral excited atoms of chromium (Cr I lines). The experiments are also performed under 10-5 torr ultra pure oxygen partial pressure. The results demonstrate that the measured intensities of the emitted photons are always higher in the presence of oxygen and even higher than those obtained for Cr2O3 target. In the presence of oxygen vapor we assume that an oxide film is formed on the chromium surface which is responsible of the increase of photon emission. This variation in the intensities is correctly explained in the model of electron transfer processes between the excited sputtered atom and the bombarded surface. This model suggests that the structure formed on the Cr surface in the case of oxygenated chromium is closer to that of Cr2O3 oxide.

  8. Aluminum work function: Effect of oxidation, mechanical scraping and ion bombardment

    Science.gov (United States)

    Vinet, P.; Lemogne, T.; Montes, H.

    1985-01-01

    Surface studies have been performed on aluminum polycrystalline surfaces which have been mechanically scraped. Such studies were initiated in order to understand surface effects occurring in tribological processes which involve rubbing surfaces and the effects of adsorption of oxygen. To characterize the surfaces, the following three different experimental approaches have been used: (1) X.P.S. (X-ray photoelectron spectroscopy), in order to check the cleanliness of the surfaces and follow the adsorption and oxidation kinetics; (2) Analysis of the work function changes by following the energy spectra of secondary electrons emitted under low energy electron bombardment; and (3) Analysis of photoemission intensities under U.V. excitation. The reference state being chosen to be the surface cleaned by ion bombardment and exposures to oxygen atmospheres have been shown to lower the work function of clean polycrystalline aluminum by 1.2 eV. The oxygen pressure is found to affect only the kinetics of these experiments. Mechanical scraping has been shown to induce a decrease ( 0.3 eV) in the work function, which could sharply modify the kinetics of adsorption on the surface.

  9. AES, EELS and TRIM simulation method study of InP(100 subjected to Ar+, He+ and H+ ions bombardment.

    Directory of Open Access Journals (Sweden)

    Abidri B.

    2012-06-01

    Full Text Available Auger Electron Spectroscopy (AES and Electron Energy Loss Spectroscopy (EELS have been performed in order to investigate the InP(100 surface subjected to ions bombardment. The InP(100 surface is always contaminated by carbon and oxygen revealed by C-KLL and O-KLL AES spectra recorded just after introduction of the sample in the UHV spectrometer chamber. The usually cleaning process of the surface is the bombardment by argon ions. However, even at low energy of ions beam (300 eV indium clusters and phosphorus vacancies are usually formed on the surface. The aim of our study is to compare the behaviour of the surface when submitted to He+ or H+ ions bombardment. The helium ions accelerated at 500V voltage and for 45 mn allow removing contaminants but induces damaged and no stoichiometric surface. The proton ions were accelerated at low energy of 500 eV to bombard the InP surface at room temperature. The proton ions broke the In-P chemical bonds to induce the formation of In metal islands. Such a chemical reactivity between hydrogen and phosphorus led to form chemical species such as PH and PH3, which desorbed from the surface. The chemical susceptibly and the small size of H+ advantaged their diffusion into bulk. Since the experimental methods alone were not able to give us with accuracy the disturbed depth of the target by these ions. We associate to the AES and EELS spectroscopies, the TRIM (Transport and Range of Ions in Matter simulation method in order to show the mechanism of interaction between Ar+, He+ or H+ ions and InP and determine the disturbed depth of the target by argon, helium or proton ions.

  10. Molecular dynamics study on low-energy sputtering of carbon material by Xe ion bombardment

    Science.gov (United States)

    Muramoto, T.; Hyakutake, T.

    2013-05-01

    The low-energy sputtering of carbon material under Xe ion bombardment is studied through the molecular dynamics (MD) simulation. For the normal incidence of Xe, the MD result of sputtering yield almost agrees with the experimental result by Williams et al. (AIAA-2004-3788). However, the experimental result shows a less incident angle dependence than the MD result because the experiment performed on a rough surface. It is found that the sputtered particles have memory of the projectile because the sputtered particles by the low-energy projectile undergo only a few collisions before the ejection. Low density of an amorphous carbon surface brings the decrease of the sputtering yield and the increase of high-energy sputtered atoms.

  11. Possible wave formation and martensitic transformation of iron particles in copper single crystals during argon ion bombardment

    DEFF Research Database (Denmark)

    Thölén, Anders Ragnar; Li, Chang-Hai; Easterling, K.E.

    1983-01-01

    Thin single crystal copper specimens (thickness ~250 nm) containing coherent iron particles (diameter 40–50 nm) have been bombarded with argon ions (5, 80, and 330 keV). During this process some of the iron particles transform to martensite. The transformation was observed near the exposed surface...

  12. Characterization of CdZnTe after argon ion beam bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Bensalah, H., E-mail: hakima.bensalah@uam.es [Departamento de Fisica de Materiales, Laboratorio de Crecimiento de Cristales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Hortelano, V. [GdS-Optronlab Group, Departamento Fisica Materia Condensada, Universidad de Valladolid, Edificio I-D, Paseo de Belen 1, 47011 Valladolid (Spain); Plaza, J.L. [Departamento de Fisica de Materiales, Laboratorio de Crecimiento de Cristales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Martinez, O. [GdS-Optronlab Group, Departamento Fisica Materia Condensada, Universidad de Valladolid, Edificio I-D, Paseo de Belen 1, 47011 Valladolid (Spain); Crocco, J.; Zheng, Q.; Carcelen, V.; Dieguez, E. [Departamento de Fisica de Materiales, Laboratorio de Crecimiento de Cristales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer After argon irradiation using low fluence, the defects on surface were removed. Black-Right-Pointing-Pointer The PL intensity increases after irradiation. This increase should be related to the improved quality of the CdZnTe surfaces. Black-Right-Pointing-Pointer Irradiation process lead to an elimination of Te precipitates from the surfaces of the CdZnTe samples. - Abstract: The objective of this work is to analyze the effects of argon ion irradiation process on the structure and distribution of Te inclusions in Cd{sub 1-x}Zn{sub x}Te crystals. The samples were treated with different ion fluences ranging from 2 to 8 Multiplication-Sign 10{sup 17} cm{sup -2}. The state of the samples before and after irradiation were studied by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Cathodoluminescence, Photoluminescence, and micro-Raman spectroscopy. The effect of the irradiation on the surface of the samples was clearly observed by SEM or AFM. Even for small fluences a removal of polishing scratches on the sample surfaces was observed. Likely correlated to this effect, an important enhancement in the luminescence intensity of the irradiated samples was observed. An aggregation effect of the Te inclusions seems to occur due to the Ar bombardment, which are also eliminated from the surfaces for the highest ion fluences used.

  13. Diffusion enhancement due to low-energy ion bombardment during sputter etching and deposition

    Energy Technology Data Exchange (ETDEWEB)

    Eltoukhy, A.H.; Greene, J.E.

    1980-08-01

    The effects of low-energy ion bombardment on enhancing elemental diffusion rates at both heterojunction interfaces during film deposition and over the compositionally altered layer created during sputter etching alloy targets have been considered. Depth dependent enhanced interdiffusion coefficients, expressed as D*(x)=D*(0) exp(-x/L/sub d/), where D*(0) is more than five orders of magnitude greater than thermal diffusion values, were measured in InSb/GaSb multilayer structures deposited by multitarget bias sputering. D*(0) was determined from the amplitude u of the compositional modulation in the multilayered films (layer thicknesses between 20 and 45 A) as measured by superlattice x-ray diffraction techniques. The value of D*(0) was found to increase from 3 x 10/sup -17/ to 1 x 10/sup -16/ cm/sup 2//sec as the applied substrate bias was increased from 0 to -75 V. However even at V/sub a/=0, the diffusion coefficient was enhanced owing to an induced substrate potential with respect to the positive space-charge region in the Ar discharge. The diffusion length of L/sub d/ of the ion bombardment created defects was approx.1000 A. Enhanced diffusion also has a significiant effect on the altered layer thickness x/sub e/ and the total sputtering time t/sub e/ (or ion dose) required to reach steady state during ion etching of multielement targets. The effects of using an exponentially depth dependent versus a constant value of the enhanced diffusion coefficient on calculated values of x/sub e/ and t/sub e/ in single-phase binary alloys were considered. The results show that both x/sub e/ and t/sub e/ are considerably larger using a depth dependent D*(x), when L/sub d/D*(0)/v, the usual case for most sputtering applications, the two solutions approach each other.

  14. Preparation of clean surfaces and Se vacancy formation in Bi2Se3 by ion bombardment and annealing

    Science.gov (United States)

    Zhou, Weimin; Zhu, Haoshan; Valles, Connie M.; Yarmoff, Jory A.

    2017-08-01

    Bismuth Selenide (Bi2Se3) is a topological insulator (TI) with a structure consisting of stacked quintuple layers. Single crystal surfaces are commonly prepared by mechanical cleaving. This work explores the use of low energy Ar+ ion bombardment and annealing (IBA) as an alternative method to produce reproducible and stable Bi2Se3 surfaces under ultra-high vacuum (UHV). It is found that a clean and well-ordered surface can be prepared by a single cycle of 1 keV Ar+ ion bombardment and 30 min of annealing. Low energy electron diffraction (LEED) and detailed low energy ion scattering (LEIS) measurements show no differences between IBA-prepared surfaces and those prepared by in situ cleaving in UHV. Analysis of the LEED patterns shows that the optimal annealing temperature is 450 °C. Angular LEIS scans reveal the formation of surface Se vacancies when the annealing temperature exceeds 520 °C.

  15. On the validity of the electron transfer model in photon emission from ion bombarded vanadium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ait El Fqih, M.; El Boujlaidi, A.; Jourdani, R.; Kaddouri, A. [Equipe de Spectroscopie and Imagerie Atomiques des Materiaux, Universite Cadi Ayyad, Marrakech (Morocco); Ait El Fqih, M. [Faculte Polydisciplinaire, Universite Chouaib Doukkali, B.P. 2390 El Jadida (Morocco)

    2011-06-15

    The spectral structure of the radiation (250-500 nm) emitted during sputtering of clean and oxygen-covered polycrystalline vanadium and V{sub 2}O{sub 5} by 5 keV Kr{sup +} ions is presented. The optical spectra obtained by bombarding the vanadium target consist of series of sharp lines, which are attributed to neutral and ionic excited V. The same lines are observed in the spectra of V{sub 2}O{sub 5} and vanadium when oxygen is present. The absolute intensities of VI and VII lines are measured under similar conditions for all spectra. The difference in photon yield from the clean and oxide vanadium targets is discussed in terms of the electron-transfer processes between the excited sputtered and electronic levels of the two types of surfaces. We have examined the existing models of ionisation, excitation, neutralisation and de-excitation of atomic particles in the vicinity of solid surfaces. Continuum radiation was also observed and interpreted as a result of the emission of excited molecules of the metal-oxide. (authors)

  16. On the validity of the electron transfer model in photon emission from ion bombarded vanadium surfaces

    Science.gov (United States)

    El Fqih, M. Ait; El Boujlaïdi, A.; Jourdani, R.; Kaddouri, A.

    2011-06-01

    The spectral structure of the radiation (250-500 nm) emitted during sputtering of clean and oxygen-covered polycrystalline vanadium and V2O5 by 5 keV Kr+ ions is presented. The optical spectra obtained by bombarding the vanadium target consist of series of sharp lines, which are attributed to neutral and ionic excited V. The same lines are observed in the spectra of V2O5 and vanadium when oxygen is present. The absolute intensities of VI and VII lines are measured under similar conditions for all spectra. The difference in photon yield from the clean and oxide vanadium targets is discussed in terms of the electron-transfer processes between the excited sputtered and electronic levels of the two types of surfaces. We have examined the existing models of ionisation, excitation, neutralisation and de-excitation of atomic particles in the vicinity of solid surfaces. Continuum radiation was also observed and interpreted as a result of the emission of excited molecules of the metal-oxide.

  17. Effect of ion bombardment on the surface morphology of Zn-films sputtered in an unbalanced magnetron

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J.; Matous, J.; Valvoda, V. [Academy of Sciences, Prague (Czech Republic). Inst. of Physics

    1995-02-01

    It is well known that magnetron sputtered films of low melting point T{sub m} materials have (due to their crystallisation at low substrate temperatures, T < 100{sup o}C) rough and diffusely reflecting surfaces, even when thin, for instance about 20 nm for In films. Only extremely thin films have a smooth and specular reflecting surface. This paper reports on the possibility of sputtering thick films of low T{sub m} materials with a smooth, optically specular reflecting surface using an unbalanced magnetron. To demonstrate this possibility, Zn films were studied and it was shown that a surface roughness of the film can be effectively controlled by ion bombardment of the film during growth. The smoothing of the Zn film does not depend on film thickness but on ion bombardment of the growing film. (author).

  18. Ductile extension of a lenticular bubble under high-energy ion bombardment with relation to blistering and flaking

    Science.gov (United States)

    Kamada, K.; Higashida, Y.

    1981-09-01

    A theory is given which is based on a model of the ductile extension of a crack in a material and is capable of explaining the whole process of surface exfoliation phenomena under high-energy ion bombardment, including both blistering and flaking, on the same ground, starting from a very small nucleus of a lenticular bubbble. Further, the distinction between blistering and flaking is clarified, and the relation of the exfoliation phenomeon with local swelling due to bubble formation is presented.

  19. Heavy-ion induced desorption yields of cryogenic surfaces bombarded with 4.2  MeV/u lead ions

    Directory of Open Access Journals (Sweden)

    E. Mahner

    2011-05-01

    Full Text Available The ion-induced desorption experiment, installed in the CERN Heavy-Ion Accelerator LINAC 3, has been used to study the dynamic outgassing of cryogenic surfaces. Two different targets, bare and gold-coated copper, were bombarded under perpendicular impact with 4.2  MeV/u Pb^{54+} ions. Partial pressure rises of H_{2}, CH_{4}, CO, and CO_{2} and effective desorption yields were measured at 300, 77, and 6.3 K using single shot and continuous ion bombardment techniques. We find that the heavy-ion-induced desorption yield is temperature dependent and investigate the influence of CO gas cryosorbed at 6.3 K. The gain in desorption yield reduction at cryogenic temperature vanishes after several monolayers of CO are cryosorbed on both targets. In this paper we describe the new cryogenic target assembly, the temperature-dependent pressure rise, desorption yield, and gas adsorption measurements.

  20. Room-temperature deposition of transparent conductive Al-doped ZnO thin films using low energy ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Jin, C.G.; Yu, T.; Wang, F.; Wu, X.M. [Soochow University, Department of Physics, Soochow (China); Soochow University, The Key Laboratory of Thin Films of Jiangsu, Soochow (China); Wu, Z.F. [Yancheng Institute of Technology, Yancheng (China); Wu, M.Z. [Soochow University, Department of Physics, Soochow (China); Wang, Y.Y.; Yu, Y.M. [Wenzheng College of Soochow University, Soochow (China); Zhuge, L.J. [Soochow University, The Key Laboratory of Thin Films of Jiangsu, Soochow (China); Soochow University, Analysis and Testing Center, Soochow (China)

    2012-03-15

    Al-doped zinc oxide (AZO) films are prepared on quartz substrates by dual-ion-beam sputtering deposition at room temperature ({proportional_to}25 C). An assisting argon ion beam (ion energy E{sub i} =0-300 eV) directly bombards the substrate surface to modify the properties of AZO films. The effects of assisted-ion beam energy on the characteristics of AZO films were investigated in terms of X-ray diffraction, atomic force microscopy, Raman spectra, Hall measurement and optical transmittance. With increasing assisting-ion beam bombardment, AZO films have a strong improved crystalline quality and increased radiation damage such as oxygen vacancies and zinc interstitials. The lowest resistivity of 4.9 x 10 {sup -3}{omega} cm and highest transmittance of above 85% in the visible region were obtained under the assisting-ion beam energy 200 eV. It was found that the bandgap of AZO films increased from 3.37 to 3.59 eV when the assisting-ion beam energy increased from 0 to 300 eV. (orig.)

  1. Diamond-like carbon layers modified by ion bombardment during growth and researched by Resonant Ultrasound Spectroscopy

    Science.gov (United States)

    Kocourek, Tomáš; Jelínek, Miroslav; Písařík, Petr; Remsa, Jan; Janovská, Michaela; Landa, Michal; Zemek, Josef; Havránek, Vladimír

    2017-09-01

    Biocompatible Diamond-Like Carbon (DLC) films were prepared by Pulsed Laser Deposition technique using the laser energy density of 10 J cm-2 on the graphite target. The surface of the grown film was modified during the deposition by bombardment with argon, xenon, nitrogen or oxygen ions. The ion energy (up to 150 eV) was changed by gun voltage and by ionic current. The films with high and low diamond/graphite content were prepared. Physical and mechanical properties of biocompatible DLC thin layers prepared by hybrid laser technology were studied. The composition of layers and the content trace elements were determined by the methods of Rutherford Backscattering Spectrometry and Particle Induced X-ray Emission. The content of sp2 and sp3 bonds was measured using X-ray Photoelectron Spectroscopy. For different energy of argon and oxygen ions the maximum of sp3 bonds content was found (83.63% of sp3 bonds for argon ions). All films were smooth, which was confirmed by profilometry and Atomic Force Microscopy measurements. Maximum roughness Ra and RMS was did not exceed 1 nm. The Younǵs and shear moduli were studied by Resonant Ultrasound Spectroscopy. The Young's Modulus attained the value of 601 GPa and the shear Modulus attained the value of 253 GPa at the energy of 30 eV of Ar ions. The influence of ion bombardment on DLC film properties is discussed.

  2. Angular distribution of Rh atoms desorbed from ion-bombarded Rh l brace 100 r brace : Effect of local environment

    Energy Technology Data Exchange (ETDEWEB)

    Maboudian, R.; Postawa, Z.; El-Maazawi, M.; Garrison, B.J.; Winograd, N. (Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 (USA))

    1990-10-15

    Energy-resolved angular distributions of Rh atoms desorbed by 5 keV Ar-ion bombardment of the Rh{l brace}100{r brace} surface are measured with use of a multiphoton resonance ionization technique. The results are shown to be in good agreement with molecular-dynamics simulations of the ion-impact event using the same interaction potential optimized previously to describe desorption from Rh{l brace}111{r brace}. In addition, by analyzing contour plots of the surface potential energy, the trend in the experimental results for Rh{l brace}100{r brace} and those previously published for Rh{l brace}111{r brace} are well explained. Based on this analysis, it is concluded that the peak in the polar-angle distribution of neutral particles desorbed from ion-bombarded single crystals is mainly determined by the relative positions of surface atoms which influence the trajectory of an exiting particle via channeling and blocking. Moreover, the anisotropy of the momentum imparted to the surface atoms in the last collision leads to an enhancement of ejection along certain crystallographic directions.

  3. Systematic analysis of neutron yields from thick targets bombarded by heavy ions and protons with moving source model

    CERN Document Server

    Kato, T; Nakamura, T

    2002-01-01

    A simple phenomenological analysis using the moving source model has been performed on the neutron energy spectra produced by bombarding thick targets with high energy heavy ions which have been systematically measured at the Heavy-Ion Medical Accelerator (HIMAC) facility (located in Chiba, Japan) of the National Institute of Radiological Sciences (NIRS). For the bombardment of both heavy ions and protons in the energy region of 100-500 MeV per nucleon, the moving source model incorporating the knock-on process could be generally successful in reproducing the measured neutron spectra within a factor of two margin of accuracy. This phenomenological analytical equation is expressed having several parameters as functions of atomic number Z sub p , mass number A sub p , energy per nucleon E sub p for projectile, and atomic number Z sub T , mass number A sub T for target. By inputting these basic data for projectile and target into this equation we can easily estimate the secondary neutron energy spectra at an emi...

  4. From crater functions to partial differential equations: a new approach to ion bombardment induced nonequilibrium pattern formation

    Energy Technology Data Exchange (ETDEWEB)

    Norris, Scott A; Brenner, Michael P; Aziz, Michael J [Harvard School of Engineering and Applied Sciences, Cambridge MA 02138 (United States)

    2009-06-03

    We develop a methodology for deriving continuum partial differential equations for the evolution of large-scale surface morphology directly from molecular dynamics simulations of the craters formed from individual ion impacts. Our formalism relies on the separation between the length scale of ion impact and the characteristic scale of pattern formation, and expresses the surface evolution in terms of the moments of the crater function. We demonstrate that the formalism reproduces the classical Bradley-Harper results, as well as ballistic atomic drift, under the appropriate simplifying assumptions. Given an actual set of converged molecular dynamics moments and their derivatives with respect to the incidence angle, our approach can be applied directly to predict the presence and absence of surface morphological instabilities. This analysis represents the first work systematically connecting molecular dynamics simulations of ion bombardment to partial differential equations that govern topographic pattern-forming instabilities.

  5. From crater functions to partial differential equations: a new approach to ion bombardment induced nonequilibrium pattern formation.

    Science.gov (United States)

    Norris, Scott A; Brenner, Michael P; Aziz, Michael J

    2009-06-03

    We develop a methodology for deriving continuum partial differential equations for the evolution of large-scale surface morphology directly from molecular dynamics simulations of the craters formed from individual ion impacts. Our formalism relies on the separation between the length scale of ion impact and the characteristic scale of pattern formation, and expresses the surface evolution in terms of the moments of the crater function. We demonstrate that the formalism reproduces the classical Bradley-Harper results, as well as ballistic atomic drift, under the appropriate simplifying assumptions. Given an actual set of converged molecular dynamics moments and their derivatives with respect to the incidence angle, our approach can be applied directly to predict the presence and absence of surface morphological instabilities. This analysis represents the first work systematically connecting molecular dynamics simulations of ion bombardment to partial differential equations that govern topographic pattern-forming instabilities.

  6. Modeling of metal nanocluster growth on patterned substrates and surface pattern formation under ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, Satoshi

    2012-11-01

    are considered as local transition events constrained in potential energy wells over certain local time periods. These processes are represented by Markov chains of multi-dimensional Boolean valued functions in three dimensional lattice space. Consequently, the fluctuating system evolution process is implemented as a Markov chain of equivalence class objects. It is shown that the process can be characterized by the acceptance of metastable local transitions. The method is applied to a problem of Au and Ag cluster growth on a rippled surface. The simulation predicts the existence of a morphology dependent transition time limit from a local metastable to stable state for subsequent cluster growth by accretion. The third topic is the formation of ripple structures on ion bombarded semiconductor surfaces treated in the first topic as the prepatterned substrate of the metallic deposition. This intriguing phenomenon has been known since the 1960's and various theoretical approaches have been explored. These previous models are discussed and a new non-linear model is formulated, based on the local atomic flow and associated density change in the near surface region. Within this framework ripple structures are shown to form without the necessity to invoke surface diffusion or large sputtering as important mechanisms. The model can also be extended to the case where sputtering is important and it is shown that in this case, certain 'magic' angles can occur at which the ripple patterns are most clearly defined. The results including some analytic solutions of the nonlinear equation of motions are in very good agreement with experimental observation.

  7. Ion-bombardment-induced reduction in vacancies and its enhanced effect on conductivity and reflectivity in hafnium nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Zhiqing; Wang, Jiafu; Hu, Chaoquan; Zhang, Xiaobo; Dang, Jianchen; Gao, Jing; Zheng, Weitao [Jilin University, School of Materials Science and Engineering, Key Laboratory of Mobile Materials, MOE, and State Key Laboratory of Superhard Materials, Changchun (China); Zhang, Sam [Nanyang Technological University, School of Mechanical and Aerospace Engineering, Singapore (Singapore); Wang, Xiaoyi [Chinese Academy of Sciences, Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics, Fine Mechanics and Physics, Changchun (China); Chen, Hong [Jilin University, Department of Control Science and Engineering, Changchun (China)

    2016-08-15

    Although the role of ion bombardment on electrical conductivity and optical reflectivity of transition metal nitrides films was reported previously, the results were controversial and the mechanism was not yet well explored. Here, we show that proper ion bombardment, induced by applying the negative bias voltage (V{sub b}), significantly improves the electrical conductivity and optical reflectivity in rocksalt hafnium nitride films regardless of level of stoichiometry (i.e., in both near-stoichiometric HfN{sub 1.04} and over-stoichiometric HfN{sub 1.17} films). The observed improvement arises from the increase in the concentration of free electrons and the relaxation time as a result of reduction in nitrogen and hafnium vacancies in the films. Furthermore, HfN{sub 1.17} films have always much lower electrical conductivity and infrared reflectance than HfN{sub 1.04} films for a given V{sub b}, owing to more hafnium vacancies because of larger composition deviation from HfN exact stoichiometry (N:Hf = 1:1). These new insights are supported by good agreement between experimental results and theoretical calculations. (orig.)

  8. Effect of field cooling process and ion-beam bombardment on the exchange bias of NiCo/(Ni, Co)O bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Li, X. [Department of Electrical and Electronic Engineering, The University of Hong Kong (Hong Kong); Lin, K.-W., E-mail: kwlin@dragon.nchu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Liu, H.-Y. [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Wei, D.-H. [National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan (China); Li, G.J. [Department of Electrical and Electronic Engineering, The University of Hong Kong (Hong Kong); Pong, P.W.T., E-mail: ppong@eee.hku.hk [Department of Electrical and Electronic Engineering, The University of Hong Kong (Hong Kong)

    2014-11-03

    The research on exchange coupled ferromagnetic/antiferromagnetic (FM/AF) bilayers has been the foundation of spintronic applications such as hard disk reading heads and spin torque oscillators. In order to further explore the exchange bias behavior of NiCo/(Ni, Co)O bilayers, effect of field cooling process, magnetic angular dependence, and ion-beam bombardment was investigated. The difference in film composition resulted in remarkable distinction in crystalline structures and domain patterns. The exchange bias field (H{sub ex}) in the bilayer systems exhibited a strong angular dependence. The negative H{sub ex} after a field cooling process indicated that the polarity of H{sub ex} can be defined by aligning the magnetization orientation of the FM NiCo layer with the applied field. Moreover, enhanced exchange bias effect was observed in the NiCo/(Ni, Co)O bilayers that resulted from the surface of the (Ni, Co)O layers bombarded with different Ar{sup +} ion-beam energies using End-Hall voltages from 0 V to 150 V. The interface spin structures as well as the surface domain patterns were altered by the ion-beam bombardment process. These results indicated that the exchange bias field of NiCo/(Ni, Co)O bilayer systems could be tailored by field cooling process, angular dependence of magnetic properties, and post ion-beam bombardment. - Highlights: • Strong angular dependence was observed in the exchange bias of NiCo/(Ni, Co)O bilayers. • The field cooling process resulted in negative exchange bias. • Moderate ion-beam bombardment on (NiCo)O layers enhanced exchange bias at 298 K. • High-energy ion bombardment strengthened the exchange coupling in field cooled bilayer. • The structural deformation was responsible for the change in magnetic properties.

  9. Step formation on the ion-bombarded Ag(100) surface studied by LEED and Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Teichert, C. (Max-Planck-Inst. fuer Mikrostrukturphysik, Halle (Germany)); Ammer, C. (Max-Planck-Inst. fuer Mikrostrukturphysik, Halle (Germany)); Klaua, M. (Max-Planck-Inst. fuer Mikrostrukturphysik, Halle (Germany))

    1994-11-16

    The development of the morphology of an Ag(100) single-crystal surface bombarded with 600 eV Ar[sup +] ions at 170 K and at room temperature is studied by spot profile analysis of LEED. A temperature-dependent saturation of the step density is observed and a distinct smoothing of the surface after bombardment occurs already at room temperature. Under out-of-phase condition the LEED spots show a fourfold shape that differs in orientation at both temperatures. Monte Carlo simulations of the atom removal including thermal surface diffusion reveal at 170 K the formation of left angle 100 right angle and left angle 110 right angle step edges with equal probability, whereas at room temperature rearrangement processes at the steps lead to the preferential formation of the close-packed left angle 110 right angle edges. The intensity distribution under out-of-phase condition calculated from the Monte Carlo snap shots exhibits the same temperature dependence of the spot shapes as observed experimentally. The interlayer mass transport occurring during annealing at room temperature is found to be based on jumps running downward the left angle 100 right angle step edges. (orig.)

  10. Molecular dynamics simulation for the sputtering of an Al2O3 sample bombarded with MeV Si ions

    Institute of Scientific and Technical Information of China (English)

    薛建明; 今西信嗣

    2002-01-01

    Sputtering yield and kinetic energy distribution (KED) of Al particles from an Al2Oa sample bombarded with 1-5 MeV Si ions have been simulated using the molecular dynamics method. These have also been measured experimentally with a conventional time-of-flight facility. In the simulation, a new interatomic potential specific to the Al2O3 target was developed, and both the nuclear energy loss Sn and electronic energy loss Se were taken into consideration. By carefully adjusting the simulation parameters, the simulated sputtering yields fit well with the experimental results, and the simulated KED of Al particles also fits roughly with the experimental KED after being modified theoretically.

  11. Selective atomic-level etching using two heating procedures, infrared irradiation and ion bombardment, for next-generation semiconductor device manufacturing

    Science.gov (United States)

    Shinoda, K.; Miyoshi, N.; Kobayashi, H.; Miura, M.; Kurihara, M.; Maeda, K.; Negishi, N.; Sonoda, Y.; Tanaka, M.; Yasui, N.; Izawa, M.; Ishii, Y.; Okuma, K.; Saldana, T.; Manos, J.; Ishikawa, K.; Hori, M.

    2017-05-01

    The demand for precisely controlled etching is increasing as semiconductor device geometries continue to shrink. To fulfill this demand, cyclic atomic level/layer etching will become one of the key technologies in semiconductor device manufacturing at nanometer dimensions. This review describes recent trends in semiconductor devices and some of the latest results on cyclic atomic-level etching. In particular, it focuses on two types of cyclic etching that use different heating procedures: infrared irradiation for isotropic etching and Ar+ ion bombardment for anisotropic etching. It describes how an inductively-coupled-plasma down-flow etching apparatus with infrared lamps can be used for isotropic cyclic etching. The isotropic cyclic etching of SiN involves the formation and thermal desorption of ammonium hexafluorosilicate-based surface modified layers. This method features high selectivity with respect to SiO2, atomic-level control of the amount of SiN etching, and isotropic etched features. On the other hand, the anisotropic cyclic etching with Ar+ ion bombardment uses a microwave electron-cyclotron-resonance plasma etching apparatus. The anisotropic process for poly Si is composed of cyclic repetitions of chlorine adsorption and Ar+ ion bombardment. The anisotropic process for SiN is composed of cyclic repetitions involving an adsorption step using hydrofluorocarbon chemistry and a desorption step using Ar+ ion bombardment. Potential applications of these isotropic/anisotropic cyclic etching processes are described.

  12. Influence of substrate pre-treatments by Xe{sup +} ion bombardment and plasma nitriding on the behavior of TiN coatings deposited by plasma reactive sputtering on 100Cr6 steel

    Energy Technology Data Exchange (ETDEWEB)

    Vales, S., E-mail: sandra.vales@usp.br [Universidade de São Paulo (USP), Escola de Engenharia de São Carlos, Av. Trabalhador São Carlense 400, São Carlos, SP CEP 13566-590 (Brazil); Brito, P., E-mail: ppbrito@gmail.com [Pontifícia Universidade Católica de Minas Gerais (PUC-MG), Av. Dom José Gaspar 500, 30535-901 Belo Horizonte, MG (Brazil); Pineda, F.A.G., E-mail: pipe8219@gmail.com [Universidade de São Paulo (USP), Escola de Engenharia de São Carlos, Av. Trabalhador São Carlense 400, São Carlos, SP CEP 13566-590 (Brazil); Ochoa, E.A., E-mail: abigail_ochoa@hotmail.com [Universidade Estadual de Campinas (UNICAMP), Campus Universitário Zeferino Vaz, Barão Geraldo, Campinas, SP CEP 13083-970 (Brazil); Droppa, R., E-mail: roosevelt.droppa@ufabc.edu.br [Universidade Federal do ABC (UFABC), Av. dos Estados, 5001, Santo André, SP CEP 09210-580 (Brazil); Garcia, J., E-mail: jose.garcia@sandvik.com [Sandvik Coromant R& D, Lerkrogsvägen 19, SE-12680, Stockholm (Sweden); Morales, M., E-mail: monieriz@gmail.com [Universidade Estadual de Campinas (UNICAMP), Campus Universitário Zeferino Vaz, Barão Geraldo, Campinas, SP CEP 13083-970 (Brazil); Alvarez, F., E-mail: alvarez@ifi.unicamp.br [Universidade Estadual de Campinas (UNICAMP), Campus Universitário Zeferino Vaz, Barão Geraldo, Campinas, SP CEP 13083-970 (Brazil); and others

    2016-07-01

    In this paper the influence of pre-treating a 100Cr6 steel surface by Xe{sup +} ion bombardment and plasma nitriding at low temperature (380 °C) on the roughness, wear resistance and residual stresses of thin TiN coatings deposited by reactive IBAD was investigated. The Xe{sup +} ion bombardment was carried out using a 1.0 keV kinetic energy by a broad ion beam assistance deposition (IBAD, Kaufman cell). The results showed that in the studied experimental conditions the ion bombardment intensifies nitrogen diffusion by creating lattice imperfections, stress, and increasing roughness. In case of the combined pre-treatment with Xe{sup +} ion bombardment and subsequent plasma nitriding, the samples evolved relatively high average roughness and the wear volume increased in comparison to the substrates exposed to only nitriding or ion bombardment. - Highlights: • Effect of Xe ion bombardment and plasma nitriding on TiN coatings was investigated. • Xe ion bombardment with 1.0 KeV increases nitrogen retention in plasma nitriding. • 1.0 KeV ion impact energy causes sputtering, thus increasing surface roughness. • TiN coating wear is minimum after plasma nitriding due to lowest roughness.

  13. Plasma damage mechanisms in low k organosilicate glass and their inhibition by Ar ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Kazi, Haseeb; Kelber, Jeffry A., E-mail: kelber@unt.edu [Center for Electronic Materials Processing and Integration and Department of Chemistry, University of North Texas, Denton, Texas 76203 (United States)

    2014-03-15

    In-situ x-ray photoelectron spectroscopy and ex-situ Fourier transform infrared spectroscopy studies of vacuum ultraviolet (VUV) photons with or without O{sub 2}, and O radicals point to distinct mechanisms of carbon abstraction in nanoporous organosilicate glass (OSG) films. VUV alone in the absence of O{sub 2} results in Si-CH{sub 3} bond scission and recombination preferentially at silicon monomethyl sites, obeying diffusion kinetics. In contrast, the presence of O{sub 2} interferes with recombination, resulting in diffusion-dominated carbon loss kinetics, enhanced Si oxidation, and greatly accelerating the rate of carbon loss in both the near surface and bulk regions of the OSG, at both monomethyl and dimethyl sites. Carbon abstraction due to exposure to (O({sup 3}P)) does not follow diffusion kinetics, and such interactions yield a SiO{sub 2}-like surface layer inhibiting further O diffusion. Results indicate that diffusion-dominated carbon abstraction kinetics previously observed for OSG exposure to O{sub 2} plasma damage is primarily attributable to the diffusion of O{sub 2} down OSG nanopores, reacting at photoactivated sites, rather than the diffusion of O radicals. OSG pretreatment by 900 eV Ar{sup +} bombardment effectively inhibits both VUV + O{sub 2} and O damage mechanisms by formation of ∼1 nm thick SiO{sub 2}-like surface region that inhibits both O and O{sub 2} diffusion.

  14. Measurements of secondary neutrons producted from thick targets bombarded by heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Kurosawa, T.; Nakamura, T. [Tohoku Univ., Sendai (Japan). Cyclotron and Radioisotope Center; Nakao, N.; Shibata, T.; Uwamino, Y.; Nakanishi, N.; Fukumura, A.; Kumamoto, Y.

    1997-03-01

    We measured neutron angular and energy distributions from high energy heavy ions stopping in targets of carbon, aluminum, copper and lead at HIMAC. These spectra are much harder for the lighter target nucleus like carbon. This means that the momentum transfer in the forward direction from heavy ion beam to lighter nuclei is much higher than that to heavier nuclei. (author)

  15. Microstructural and Tribological Characterization of Duplex Coatings with Additional Ion Bombardment

    Institute of Scientific and Technical Information of China (English)

    B.(S)kori(c); D.Kaka(s); M.Rakita

    2004-01-01

    A duplex surface treatment involves the sequential application of two surface technologies to produce a surface composition with combined properties. A typical duplex process involves plasma nitriding and the PVD coating treatment of steels. In the paper are presented characteristics of hard coatings, type TiN, produced by classic technology PVD (physical vapour deposition) and IBAD (ion beam assisted deposition). Subsequent ion implantation was provided with N5+ions. The dependence of friction coefficient was investigated by means of tribometer (pin-on-ring). The sliding pair was TiN thin coating on steel pin combined with steel ring without coating. The ring was produced from hardenable steel.

  16. Microstructural and Tribological Characterization of Duplex Coatings with Additional Ion Bombardment

    Institute of Scientific and Technical Information of China (English)

    B.Skorie; D.Kakas; M.akita

    2004-01-01

    A duplex surface treatment involves the sequential application of two surface technologies to produce a surface composition with combined properties. A typical duplex process involves plasma nitriding and the PVD coating treatment of steels. In the paper are presented characteristics of hard coatings, type TiN, produced by classic technology PVD (physical vapour deposition) and IBAD (ion beam assisted deposition). Subsequent ion implantation was provided with N5+ ions. The dependence of friction coefficient was investigated by means of tribometer (pin-on-ring). The sliding pair was TiN thin coating on steel pin combined with steel ring without coating. The ring was produced from hardenable steel.

  17. Uranium targets sandwiched between carbon layers for use on target wheels and on a Wobbler in heavy-ion bombardments

    Energy Technology Data Exchange (ETDEWEB)

    Folger, H.; Hartmann, W.; Klemm, J.; Thalheimer, W. (Gesellschaft fuer Schwerionenforschung m.b.H., Darmstadt (Germany, F.R.))

    1989-10-01

    Uranium layers of {approx equal} 0.4 mg/cm{sup 2} are evaporated by means of a 6 kW electron-beam gun onto 0.04 mg/cm{sup 2} thick carbon films in a high-vacuum process; a protecting layer of {approx equal} 0.01 mg/cm{sup 2} of carbon is added in the same vacuum cycle. The evaporation- and deposition yields are discussed and measurements of target characteristics are described. C/U/C sandwich targets in the shape of a sector of an annulus are prepared for use on rotating target wheels of 155 mm radius to be bombarded with a pulsed beam of heavy ions. One type of circular targets of 20 mm in diameter is mounted to a target wobbler. Both, wheel and wobbler, distribute the intensity of the heavy-ion beam to a larger area to reduce radiation damages. Examples of target applications will be mentioned. (orig.).

  18. Pattern transition from nanohoneycomb to nanograss on germanium by gallium ion bombardment

    Science.gov (United States)

    Zheng Xiao-Hu郑, 晓虎; Zhang Miao张, 苗; Huang An-Ping黄, 安平; Xiao Zhi-Song肖, 志松; Paul, K. Chu朱 剑 豪; Wang Xi王, 曦; Di Zeng-Feng狄, 增峰

    2015-05-01

    During the irradiation of Ge surface with Ga+ ions up to 1017 ions·cm-2, various patterns from ordered honeycomb to nanograss structure appear to be decided by the ion beam energy. The resulting surface morphologies have been studied by scanning electron microscopy and atomic force microscopy. For high energy Ga+ irradiation (16-30 keV), by controlling the ion fluence, we have captured that the equilibrium nanograss morphology also originates from the ordered honeycomb structure. When honeycomb holes are formed by ion erosion, heterogeneous distribution of the deposited energy along the holes leads to viscous flow from the bottom to the plateau. Redistribution of target atoms results in the growth of protuberances on the plateau, and finally the pattern evolution from honeycomb to nanograss with an equilibrium condition. Project supported by the National Natural Science Funds for Excellent Young Scholar, China (Grant No. 51222211), the National Natural Science Foundation of China (Grant Nos. 61176001 and 61006088), the National Basic Research Program of China (Grant No. 2010CB832906), the Pujiang Talent Project of Shanghai, China (Grant No. 11PJ1411700), the Hong Kong Research Grants Council (RGC) General Research Funds (GRF), China (Grant No. 112212), the City University of Hong Kong of Hong Kong Applied Research Grant (ARG), China (Grant No. 9667066), and the International Collaboration and Innovation Program on High Mobility Materials Engineering of Chinese Academy of Sciences.

  19. Defect production and annihilation in metals through electronic excitation by energetic heavy ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Iwase, Akihiro [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    Defect production, radiation annealing and defect recovery are studied in Ni and Cu irradiated with low-energy ({approx}1-MeV) and high-energy ({approx}100-MeV) ions. Irradiation of Ni with {approx}100-MeV ions causes an anomalous reduction, or even a complete disappearance of the stage-I recovery. This result shows that the energy transferred from excited electrons to lattice atoms through the electron-lattice interaction contributes to the annihilation of the stage-I interstitials. This effect is also observed in Ni as a large radiation annealing during 100-MeV heavy ion irradiation. On the other hand, in Cu thin foils, we find the defect production process strongly associated with electron excitation, where the defect production cross section is nearly proportional to S{sub e}{sup 2}. (author)

  20. Channeling Effect in Polycrystalline Deuterium-Saturated CVD Diamond Target Bombarded by Deuterium Ion Beam

    CERN Document Server

    Bagulya, A V; Negodaev, M A; Rusetskii, A S; Chubenko, A P; Ralchenko, V G; Bolshakov, A P

    2014-01-01

    At the ion accelerator HELIS at the LPI, the neutron yield is investigated in DD reactions within a polycrystalline deuterium-saturated CVD diamond, during an irradiation of its surface by a deuterium ion beam with the energy less than 30 keV. The measurements of the neutron flux in the beam direction are performed in dependence on the target angle, \\b{eta}, with respect to the beam axis. These measurements are performed using a multichannel detector based on He3 counters. A significant anisotropy in neutron yield is observed, it was higher by a factor of 3 at \\b{eta}=0 compared to that at \\b{eta} = +-45{\\deg}. The possible reasons for the anisotropy, including ion channeling, are discussed.

  1. Production of waveguides in LiF by MeV ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, J.A.M. [USP, Institute of Physics, CP 66318, 05315-970 Sao Paulo, SP (Brazil)]. E-mail: jamp@fge.if.usp.br; Cremona, M. [PUC-Rio, Physics Department, CP 38071, 22452-970 Rio de Janeiro, RJ (Brazil); Pelli, S. [Nello Carrara Institute of Applied Physics - CNR, Optoelectronics and Photonics Department, via Panciatichi 64, 50127 Firenze (Italy); Macchione, E.L.A. [USP, Institute of Physics, CP 66318, 05315-970 Sao Paulo, SP (Brazil); Koide, K. [USP, Institute of Physics, CP 66318, 05315-970 Sao Paulo, SP (Brazil); Vasconcelos, S.S. [USP, Institute of Physics, CP 66318, 05315-970 Sao Paulo, SP (Brazil); Righini, G.C. [Nello Carrara Institute of Applied Physics - CNR, Optoelectronics and Photonics Department, via Panciatichi 64, 50127 Florence (Italy)

    2005-10-15

    Alkali fluorides containing color centers are promising systems for applications in new integrated optical devices like active waveguides and color center lasers. In this work, we report the development of a simple method, based on high-energy ion beam irradiation, to create active waveguides in alkali halide materials. MeV carbon and helium beams at normal incidence were used to irradiate lithium fluoride crystals, with different ion doses varying from 10{sup 14} up to 10{sup 16} cm{sup -2}, producing thin colored strips. Irradiated waveguides were also characterized by means of optical absorption spectroscopy in order to obtain the distribution of the color centers induced by the ion beam. The results confirm the feasibility of integrated active devices based on color centers in LiF such as tunable light amplifiers, lasers and hybrid optoelectronic components.

  2. Level-energy-dependent mean velocities of excited tungsten atoms sputtered by krypton-ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Nogami, Keisuke; Sakai, Yasuhiro; Mineta, Shota [Department of Physics, Toho University, Miyama, Funabashi, Chiba 274-8510 (Japan); Kato, Daiji; Murakami, Izumi [National Institute for Fusion Science, Toki, Gifu 509-5292, Japan and Department of Fusion Science, School of Physical Sciences, SOKENDAI (The Graduate University for Advanced Studies), Toki, Gifu 509-5292 (Japan); Sakaue, Hiroyuki A. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Kenmotsu, Takahiro [Department of Biomedical Engineering, Faculty of Life and Medical Sciences, Doshisha University, Tatara-Miyakodani, Kyotanabe, Kyoto 610-0394 (Japan); Furuya, Kenji [Faculty of Arts and Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Motohashi, Kenji, E-mail: motohashi@toyo.jp [Department of Biomedical Engineering, Faculty of Science and Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585, Japan and Bio-Nano Electronics Research Centre, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585 (Japan)

    2015-11-15

    Visible emission spectra were acquired from neutral atoms sputtered by 35–60 keV Kr{sup +} ions from a polycrystalline tungsten surface. Mean velocities of excited tungsten atoms in seven different 6p states were also obtained via the dependence of photon intensities on the distance from the surface. The average velocities parallel to the surface normal varied by factors of 2–4 for atoms in the different 6p energy levels. However, they were almost independent of the incident ion kinetic energy. The 6p-level energy dependence indicated that the velocities of the excited atoms were determined by inelastic processes that involve resonant charge exchange.

  3. Neutron measurements around a beam dump bombarded by high energy protons and lead ions

    Science.gov (United States)

    Agosteo, S.; Birattari, C.; Foglio Para, A.; Silari, M.; Ulrici, L.

    2001-02-01

    Measurements of the spectral fluence and the ambient dose equivalent of secondary neutrons produced by 250 GeV/ c protons and 158 GeV/ c per nucleon lead ions were performed at CERN around a thick beam dump. The experimental results obtained with protons were compared with calculations performed with the FLUKA Monte Carlo code. As the available Monte Carlo codes do not transport particles with mass larger than one atomic mass unit, it is shown that for high energy heavy ions, estimates can be carried out by scaling the result of a Monte Carlo calculation for protons by the projectile mass number.

  4. Production of Oxidants by Ion Bombardment of Icy Moons in the Outer Solar System

    Directory of Open Access Journals (Sweden)

    Philippe Boduch

    2011-01-01

    Full Text Available Our groups in Brazil, France and Italy have been active, among others in the world, in performing experiments on physical-chemical effects induced by fast ions colliding with solids (frozen gases, carbonaceous and organic materials, silicates, etc. of astrophysical interest. The used ions span a very large range of energies, from a few keV to hundreds MeV. Here we present a summary of the results obtained so far on the formation of oxidants (hydrogen peroxide and ozone after ion irradiation of frozen water, carbon dioxide and their mixtures. Irradiation of pure water ice produces hydrogen peroxide whatever is the used ion and at different temperatures. Irradiation of carbon dioxide and water frozen mixtures result in the production of molecules among which hydrogen peroxide and ozone. The experimental results are discussed in the light of the relevance they have to support the presence of an energy source for biosphere on Europa and other icy moons in the outer Solar System.

  5. Effects of low energy ion bombardment on the formation of cubic iron mononitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, Pilar [Departamento de Física Aplicada M-12, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Figuera, Juan de la [Instituto de Química-Física “Rocasolano”, CSIC, Serrano 119, 28006 Madrid (Spain); Sanz, José M. [Departamento de Física Aplicada M-12, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Marco, José F. [Instituto de Química-Física “Rocasolano”, CSIC, Serrano 119, 28006 Madrid (Spain)

    2013-07-31

    The formation of cubic nitrides with stoichiometry close to FeN obtained by ion assisted sputter deposition has been studied as a function of deposition parameters. In particular, we have explored the influence of the energy deposited by the assistant beam per deposited Fe atom to understand changes in composition, phase formation and nanocrystallinity of the films. An optimum N{sub 2}{sup +} ion energy and a J{sub N}/J{sub Fe} ratio (J{sub N} and J{sub Fe} represent the current density of N{sub 2}{sup +} ions and Fe atoms respectively) have been determined in order to obtain only iron mononitride phases. X-ray diffraction and Mössbauer spectroscopy revealed a phase evolution from ε-Fe{sub x(x≈2)}N to γ″ and γ‴-FeN as the N{sub 2}{sup +} ion energy and the J{sub N}/J{sub Fe} flux ratio increase. Pure nanocrystalline iron mononitride, with nitrogen content close to 50%, is obtained when J{sub N}/J{sub Fe} ratio reaches 5.9 and the N{sub 2}{sup +} ion energy is 63.4 eV. Further increments of N{sub 2}{sup +} energies and J{sub N}/J{sub Fe} values reverse this behavior and a phase evolution from γ″ and γ‴-FeN to ε-Fe{sub x(x≈2)}N is found. This behavior is attributed to energy damage and resputtering phenomena. It has also been found that γ‴-FeN phase coexists with γ″-FeN phase when the deposition is performed at room temperature. - Highlights: • We have grown iron nitride FeN{sub x(0.6} {sub ≤x≤1)} thin films by dual ion beam sputtering. • Effects of N{sub 2}{sup +} ion assistance in the formation of Fe mononitride phases are studied. • Nanocrystalline Fe mononitride with a composition FeN{sub x≈1} is obtained. • A phase evolution ε → γ‴ + γ″ → ε is observed as E{sub Fe} increases. • γ‴-FeN phase coexists with γ″-FeN at room temperature deposition conditions.

  6. Electrostatic-Discharge-Induced Degradation Caused by Argon Ion Bombardment in Facet-Coating Process of GaInAsP/InP Laser Diode

    Science.gov (United States)

    Ichikawa, Hiroyuki; Ito, Masashi; Hamada, Kotaro; Yamaguchi, Akira; Nakabayashi, Takashi

    2008-10-01

    Electrostatic discharge (ESD)-induced degradation is one of the most important reliability issues of GaInAsP/InP laser diodes. We investigated the relation between ion irradiation in the facet-coating process and ESD-induced degradation. We used electron-beam evaporation with two types of argon ion irradiation for facet-coating. One type of irradiation is used for facet cleaning, in which argon ions bombard the facet directly. Although the ion energy was as low as 40 eV, a lack of phosphorus and enhanced oxidation were found on the ion-irradiated surface. Furthermore, an increase in the surface recombination current and the enhancement of ESD-induced degradation were observed by extending the ion irradiation time. The other type of irradiation is used to promote evaporation. Here, argon ions do not bombard the facet directly. Thus, it had little effect on ESD-induced degradation. From these results, we successfully confirmed that direct ion irradiation increases surface recombination and accelerates ESD-induced degradation even if the ion energy is as low as 40 eV.

  7. Energetic neutral atoms emitted from ice by ion bombardment under Ganymede surface conditions

    Science.gov (United States)

    Wieser, Martin; Barabash, Stas; Futaana, Yoshifumi; Wurz, Peter

    2013-04-01

    Magnetospheric or solar wind ions directly interacting with a planetary surface result in backscattering or sputtering of energetic neutral atoms. One example is the solar wind interaction with the surface of the Moon, where the produced energetic neutral atoms were observed by the Sub-keV Atom Reflecting Analyzer instrument (SARA) on Chandrayaan-1. At Jupiter, magnetospheric plasma interacts in a similar way with the surface of the Galilean moons. However, the emission of energetic neutral atoms from "dirty" ices as found e.g. on Ganymede's surface is poorly understood. We set up an experiment to study the ion to surface interaction under Ganymede surface environment conditions using the unique capabilities of the MEFISTO test facility at University of Bern. Ions of various species and energies up to 33 keV/q were impacted on a block of ice made from a mixture of water, NaCl and dry ice. The energetic neutral atoms produced by the interaction were detected with the prototype of the Jovian Neutrals Analyzer instrument (JNA.) JNA is proposed as part of the Particle Environment Package (PEP) for ESA's JUICE mission to Jupiter and instrument is based on the Energetic Energetic Neutral Atom instrument (ENA) built for the BepiColombo Magnetospheric Orbiter. We present energy spectra for different ion beam species and energetic neutral atom species combinations. The data show high yields for energetic neutral atoms up to the upper end of the instrument energy range of 3.3 keV. The energy spectra of the neutral atom flux emitted from the ice could only partially be fitted by the Sigmund-Thompson formula. In some cases, but not all, a Maxwellian distribution provides a reasonable description of the data.

  8. Enhanced Load Transfer in Carbon Nanotube Bundles via Carbon-Ion Bombardment

    Science.gov (United States)

    Carpena-Nunez, Jennifer; Hernandez, Jose A.; Siochi, Emilie J.; Kim, Jae-Woo; Fonseca, Luis F.

    2014-03-01

    Carbon Nanotubes (CNTs) are ideal candidates for structural composites due to their high modulus and strength, and low weight and density. However, achieving their exceptional mechanical performance at the macroscale is an ongoing challenge, as individual CNTs within bundles are held together by weak van der Waals forces. The current work aims to address issues related to crosslinking CNTs via carbon-ion irradiation to achieve the mechanical performance promised by CNTs. Samples irradiated with a carbon-ion dose of ~ 1013-1014 cm-2 and kinetic energies ranging from 9-25keV show partial amorphization at the outermost layer of the CNT bundle, as theoretically predicted. Mechanical data collected via in-situ Transmission Electron Microscopy-Atomic Force Microscopy (TEM-AFM) shows an increase in tensile and shear strength for irradiated CNT bundles of ~ 6.6GPa and ~ 100MPa, respectively. The adhesion energy between CNT bundles showed an increase from ~ 0.12-0.48 Jm-2 for pristine CNTs up to ~ 42 Jm-2 for carbon-ion irradiated bundles. In addition, enhanced shear interaction exceeding a strength value of ~ 1GPa was observed when exposed to additional amorphous carbon binding, providing a route for improved adhesion to polymer components used in structural composites. This work was supported by a NASA Space Technology Research Fellowship.

  9. Moessbauer of phase separation in FeNi multilayers under ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, L.; Paesano, A.; Brueckman, M.E. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica; Scorzelli, R.B.; Dominguez, A.B. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Shinjo, T.; Ono, T.; Hosoito, N. [Kyoto Univ. (Japan). Inst. for Chemical Research

    1997-01-01

    We investigated the effect of noble gas irradiation (He, Ne, Ar and Xe) on the Fe-Ni multilayers with a very thin modulation and nominal composition in the invar region Fe{sub 0.63} Ni{sub 0.37}. The evaluation of the formation/stability of the Fe-Ni phases formed under irradiation with different ions and doses was followed by conversion electron Moessbauer spectroscopy (CEMS). (author). 21 refs., 4 figs., 2 tabs.; e-mail: scorza at novell.cat.cbpf.br.

  10. Study of beryllium redeposition under bombardment by high intensity -low energy- hydrogen ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Gureev, V.M.; Guseva, M.I.; Danelyan, L.S. [Russian Research Centre Kurchatov Inst., Moscow (Russian Federation)] [and others

    1998-01-01

    The results of studying the erosion of beryllium under an effect of intense ion fluxes with the energy of 250 eV, at the fluences {approx}10{sup 2}1 cm{sup -2}, at the MAGRAS-stand are given. The operating conditions under which a practically-complete redeposition of the sputtered beryllium upon the target surface were experimentally-realized. A change in the microstructure of a beryllium target under sputtering and redeposition is analyzed. Some technological applications are considered. (author)

  11. Formation of Amino Acid Precursors by Bombardment of Interstellar Ice Analogs with High Energy Heavy Ions

    Science.gov (United States)

    Kobayashi, Kensei; Mita, Hajime; Yoshida, Satoshi; Shibata, Hiromi; Enomoto, Shingo; Matsuda, Tomoyuki; Fukuda, Hitoshi; Kondo, Kotaro; Oguri, Yoshiyuki; Kebukawa, Yoko

    2016-07-01

    A wide variety of organic compounds have been detected in extraterrestrial bodies. It has been recognized that carbonaceous chondrites contain pristine amino acids [1]. There are several scenarios of the formation of such extraterrestrial amino acids or their precursors. Greenberg proposed a scenario that complex organic compounds were formed in interstellar ices in dense clouds, which were brought into solar system small bodies when the solar system was formed [2]. The ice mantles of interstellar dust particles (ISDs) in dense clouds are composed of H2O, CO, CH3OH, CH4, CO2, NH3, etc. In order to verify the scenario, a number of laboratory experiments have been conducted where interstellar ice analogs were irradiated with high-energy particles [3,4] or UV [5,6], and formation of complex organic compounds including amino acid precursors were detected in the products. Though ion-molecular reactions in gaseous phase and surface reactions on the ice mantles have been studied intensively, much less works on cosmic rays-induced reaction have been reported. In order to study possible formation of complex molecules in interstellar ices, frozen mixtures of water, methanol and ammonia with various mixing ratios were irradiated with high-energy heavy ions such as carbon ions (290 MeV/u) and neon ions (400 MeV/u) from HIMAC, NIRS, Japan. For comparison, gaseous mixtures of water, ammonia, carbon monoxide, carbon dioxide, and/or methane were irradiated with protons (2.5 MeV) from a Tandem accelerator, Tokyo Tech, Japan. Amino acids in the products were determined by cation exchange HPLC after acid hydrolysis. Products, both before and after acid hydrolysis, were also characterized by FT-IR and other techniques. Amino acids were detected in the hydrolyzed products after mixture of CH3OH, NH3 and H2O with various mixing ratios were irradiated with heavy ions, including when their mixing ratio was set close to the reported value of the interstellar ices (10:1:37). In the HIMAC

  12. Directional effect on coloration in LiF crystal by H{sup +} and H{sub 2}{sup +} ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Gan Mingle; Naramoto, Hiroshi; Aoki, Yasushi; Yamamoto, Shunya; Zeng Jianer; Takeshita, Hidefumi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    In the present paper, the first results are reported about the coloration in LiF crystals induced by bombardments of single hydrogen ions (H{sup +}) and molecular hydrogen ions (H{sub 2}{sup +}) with the same velocity under the <100> aligned and random conditions. For the single hydrogen ion irradiation, the coloration is rather simple. The F-type color center absorption under the <100> aligned condition becomes larger than that under the random condition with the dose increase because of larger fraction of electronic energy loss under channeling condition. On the contrary, the coloration for the molecular ions does not show big channeling effect. In the low dose region some difference can be seen but the difference of coloration is not observed any more with the dose increase. The pronounced coloration for molecular ions under the channeling condition is observed in comparison with that for single ions. (author)

  13. The effect of working pressure on the chemical bond structure and hydrophobic properties of PET surface treated by N ion beams bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Ding Wanyu, E-mail: dwysd_2000@163.com [Engineering Research Center of Optoelectronic Materials and Devices Education Department of Liaoning Province, Dalian, 116028 (China) and School of Materials Science and Engineering, Dalian Jiaotong University, Dalian, 116028 (China) and Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Dalian University of Technology, Ministry of Education, Dalian, 116024 (China); Ju Dongying, E-mail: dyju@sit.ac.jp [Department of Material Science and Engineering, Saitama Institute of Technology Fukaya, 369-0293 (Japan); Chai Weiping, E-mail: wpchai@djtu.edu.cn [Engineering Research Center of Optoelectronic Materials and Devices Education Department of Liaoning Province, Dalian, 116028 (China); School of Materials Science and Engineering, Dalian Jiaotong University, Dalian, 116028 (China)

    2010-09-01

    Polyethylene terephthalate (PET) surface was bombarded by N ion beams at room temperature. Varying the working pressure of the ion beams, PET surfaces with different composition and properties were obtained. Characterization by X-ray photoelectron spectrometry showed that only on film surface, ester bonds, especially C-O bonds, were broken and N element chemical bonded with C. The influence depth was less than 5 nm because of the lower ion energy (about 10{sup 3} eV). Contact angle results revealed that with increasing the working pressure of ion beams, the contact angle of PET surface to pure water increased from 51 deg. to 130 deg.. With these results, one conclusion could be deduced that the hydrophilic and hydrophobic properties of PET surface could be influenced by N atom chemical bond with C, which in turn is controlled by the working pressure of N ion beams.

  14. X-Ray Emission from Zr, Mo, In and Pb Targets Bombarded by Slow Highly Charged Arq+(q = 13, 14, 15, 16) Ions

    Institute of Scientific and Technical Information of China (English)

    CAI Xiao-Hong; SHAO Jian-Xiong; CUI Ying; XU Xu; CHEN Xi-Meng; YU De-Yang; LU Rong-Chun; SHAO Cao-Jie; LU Jun; RUAN Fang-Fang; YANG Zhi-Hu; DING Bao-Wei; ZHANG Hong-Qiang

    2005-01-01

    @@ We study the L x-ray emission from Zr, Mo and In targets and M x-ray emission from Pb target under bombardment of low energy Arq+ (q = 13, 14, 15, 16) ions. The relative x-ray yields were measured in the projectile kinetic energy range 210-360keV. It is found that the relative x-ray yields from Zr, Mo and Pb targets increase with the increasing projectile kinetic energy for Ar14+ and Ar16+ projectiles and depend on the potential energy of the projectile remarkably.

  15. INVESTIGATION OF AES AND XPS FOR THE ION BOMBARDED CARBON FILMS ON THE SURFACE OF TUNGSTEN ALLOY%离子束轰击钨合金表面碳膜的AES和XPS分析

    Institute of Scientific and Technical Information of China (English)

    李俊; 高剑; 张一云; 吴丽萍; 黄宁康; 赵纯培

    2000-01-01

    Tungsten alloy with special properties is a useful material in medical and weapon devices. Surface modification of ion technique is used to improve the surface hardness and wear resistance of tungsten alloy, where carbon films deposited with magnetron sputtering on the surface of tungsten alloy were bombarded by ion beam with different species AES and XPS analyses for these speciment show that tungsten carbide and tungsten nitride were formed due to N+ bombardment. Which is beneficial to the Surface hardness and wear resistance of tungsten alloy,but no carbide or no nitride as above with other ion species. Again,ion bombardness leads to mixing between the carbon and tungsten alloy hence improve the adhere of carbon film to the substrate.

  16. Formation mechanism and yield of molecules ejected from ZnS, CdS, and FeS{sub 2} during ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Nikzad, S.; Calaway, W.F.; Pellin, M.J.; Young, C.E.; Gruen, D.M. [Argonne National Lab., IL (United States); Tombrello, T.A. [California Inst. of Technology, Pasadena, CA (United States). Div. of Physics, Mathematics, and Astronomy

    1994-03-01

    Neutral species ejected from single crystals of ZnS, CdS, and FeS{sub 2} during ion bombardment by 3 keV Ar{sup +} were detected by laser post-ionization followed by time-of-flight mass spectrometry. While metal atoms (Fe, Zn, Cd) and S{sub 2} were the dominant species observed, substantial amounts of S, FeS, Zn{sub 2}, ZnS, Cd{sub 2}, and CdS were also detected. The experimental results demonstrate that molecules represent a larger fraction of the sputtered yield than was previously believed from secondary ion mass spectrometry experiments. In addition, the data suggest that the molecules are not necessarily formed from adjacent atoms in the solid and that a modified form of the recombination model could provide a mechanism for their formation.

  17. Photon emission produced by Kr{sup +} ions bombardment of Cr and Cr{sub 2}O{sub 3} targets

    Energy Technology Data Exchange (ETDEWEB)

    Boujlaidi, A. El, E-mail: a.elboujlaidi@uca.ma [Equipe de Spectroscopie and Imagerie Atomiques des Matériaux, Université Cadi Ayyad, Marrakech (Morocco); Hammoum, K. [Laboratoire de Mécanique, Structures et Energétique, Université Mouloud Mammeri de Tizi-Ouzou (Algeria); Jadoual, L.; Jourdani, R. [Equipe de Spectroscopie and Imagerie Atomiques des Matériaux, Université Cadi Ayyad, Marrakech (Morocco); Ait El Fqih, M. [Equipe de Spectroscopie and Imagerie Atomiques des Matériaux, Université Cadi Ayyad, Marrakech (Morocco); Ecole Nationale Supérieure d’Arts et Métiers (ENSAM), Université Hassan II Mohammedia – Casablanca (Morocco); Aouchiche, H. [Laboratoire de Mécanique, Structures et Energétique, Université Mouloud Mammeri de Tizi-Ouzou (Algeria); Kaddouri, A. [Equipe de Spectroscopie and Imagerie Atomiques des Matériaux, Université Cadi Ayyad, Marrakech (Morocco)

    2015-01-15

    The sputter induced photon spectroscopy technique was used to study the luminescence spectra of the species sputtered from chromium powder and its oxide Cr{sub 2}O{sub 3}, during 5 keV Kr{sup +} ions bombardment in vacuum better than 10{sup −7} torr. The optical spectra recorded between 350 and 470 nm exhibit discrete lines which are attributed to neutral excited atoms of chromium (Cr I lines). The experiments are also performed under 10{sup −5} torr ultra pure oxygen partial pressure. The results demonstrate that the measured intensities of the emitted photons are always higher in the presence of oxygen and even higher than those obtained for Cr{sub 2}O{sub 3} target. In the presence of oxygen vapor we assume that an oxide film is formed on the chromium surface which is responsible of the increase of photon emission. This variation in the intensities is correctly explained in the model of electron transfer processes between the excited sputtered atom and the bombarded surface. This model suggests that the structure formed on the Cr surface in the case of oxygenated chromium is closer to that of Cr{sub 2}O{sub 3} oxide.

  18. Ion bombardment measurements and simulations of a low temperature VHF PECVD SiH4-H2 discharge in the a-Si:H to μc-Si:H transition regime

    NARCIS (Netherlands)

    Landheer, K.; Goedheer, W. J.; Poulios, I.; Schropp, R. E. I.; Rath, J. K.

    2016-01-01

    We studied ion bombardment during amorphous silicon layer deposition for hydrogen dilutions 5 to 59 with mass resolved IED measurements and simulations. The trends in the peak position of H2+ and SiHy+ IEDs with increasing hydrogen dilution show good agreement between measurements and simulations. A

  19. Measurement of ion species produced due to bombardment of 450 eV N{sub 2}{sup +} ions with hydrocarbons-covered surface of tungsten: Formation of tungsten nitride

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. [Atomic Physics Laboratory, Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005 (India); Bhatt, P. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Kumar, A. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Singh, B.K.; Singh, B.; Prajapati, S. [Atomic Physics Laboratory, Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005 (India); Shanker, R., E-mail: shankerorama@gmail.com [Atomic Physics Laboratory, Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005 (India)

    2016-08-01

    A laboratory experiment has been performed to study the ions that are produced due to collisions of 450 eV N{sub 2}{sup +} ions with a hydrocarbons-covered surface of polycrystalline tungsten at room temperature. Using a TOF mass spectrometry technique, the product ions formed in these collisions have been detected, identified and analyzed. Different ion–surface reaction processes, namely, neutralization, reflection, surface induced dissociation, surface induced chemical reactions and desorption are observed and discussed. Apart from the presence of desorbed aliphatic hydrocarbon and other ions, the mass spectra obtained from the considered collisions show the formation and sputtering of tungsten nitride (WN). A layer of WN on tungsten surface is known to decrease the sputtering of bulk tungsten in fusion devices more effectively than when the tungsten is bombarded with other seeding gases (He, Ar). It is further noted that there is a negligible diffusion of N in the bulk tungsten at room temperature.

  20. Extended metastable Al solubility in cubic VAlN by metal-ion bombardment during pulsed magnetron sputtering: film stress vs subplantation

    Science.gov (United States)

    Greczynski, G.; Mráz, S.; Ruess, H.; Hans, M.; Lu, J.; Hultman, L.; Schneider, J. M.

    2017-07-01

    Dynamic ion-recoil mixing of near-film-surface atomic layers is commonly used to increase the metastable solubility limit xmax in otherwise immiscible thin film systems during physical vapor deposition. Recently, Al subplantation achieved by irradiating the film growth surface with Al+ metal-ion flux was shown to result in an unprecedented xmax for VAlN, far above values obtained with gas ion irradiation. However, it is reasonable to assume that ion irradiation necessary for subplantation also leads to a compressive stress σ buildup. In order to separate the effects of Al+ bombardment on σ and xmax, and realize low-stress high-xmax nitride alloys, we grow metastable cubic V1-xAlxN (0.17 ≤ x ≤ 0.74) films using reactive magnetron sputtering under different ion irradiation conditions. Al and V targets are operated in Ar/N2 discharges employing (i) conventional DC (Ar+, N2+), (ii) hybrid High-power pulsed magnetron sputtering (HIPIMS)/DC processing with one type of metal ion present (Al+ or V+/V2+), and (iii) HIPIMS with concurrent Al+ and V+/V2+ fluxes. Comparison to the ab initio calculated Al solubility limit reveals that xmax = 0.55 achieved with V+/V2+ irradiation is entirely accountable for by stress. In contrast, Al+ fluxes provide a substantial increase in xmax to 0.63, which is 12% higher than that expected based on the stress-induced increase in metastable solubility. Correlative stress and atom probe tomography data confirm that the metastable Al solubility enhancement is enabled by Al+ subplantation. The here proposed processing strategy allows for growth of single-phase cubic nitride alloys with significantly increased Al concentrations embodying tremendous promise for substantial improvements in high temperature oxidation resistance and mitigates the risk of stress-induced adhesive or cohesive coating failure.

  1. Fluence and fluence rate effects on electrical conductivity and shrinkage in polyimide bombarded by an ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Trigaud, T. [LEPOFI, Faculte des Sci., Limoges (France); Moliton, J.P. [LEPOFI, Faculte des Sci., Limoges (France); Jussiaux, C. [LEPOFI, Faculte des Sci., Limoges (France); Maziere, B. [LEPOFI, Faculte des Sci., Limoges (France)

    1996-02-01

    When the ion fluence is increasing, a diminishing of the thickness and a rise in electrical conductivity can be simultaneously observed with polyimide films. However, in the 100 keV energy range, a saturation limit appears in both processes. Two experimental processes are presented to increase the conductivity limit ({approx_equal}10{sup -1} S cm{sup -1} with N{sup +} ions), while the shrinkage effect is maintained or even reduced. (1) Multiple irradiations of N{sup +} ions implemented from high to low energies induce tenfold increase in conductivity, and stop the thickness decrease beyond a fluence threshold. (2) Liquid-metal ion sources (LMIS) with Ga{sup +} ions (keV) perform high conductivities (above 300 S cm{sup -1}) without notable shrinkage. (orig.).

  2. In situ noise measurements on ion bombarded thin films: 1/f-noise as a fingerprint for amorphization

    Energy Technology Data Exchange (ETDEWEB)

    Noske, Matthias; Trautvetter, Moritz; Ziemann, Paul [Institut fuer Festkoerperphysik, Universitaet Ulm (Germany)

    2009-07-01

    As has been experimentally demonstrated, the crystalline binary alloy In{sub 2}Au can be transformed into an amorphous state by low temperature ion irradiation. This transformation can be followed by measuring the ion induced increase of the electrical resistance as a function of the ion fluence. While this increase can be attributed to the built-up of static disorder, fluctuating atomic configurations may be present as well leading to resistance fluctuation and, as a consequence, to 1/f noise. To test such a possibility, patterned AuIn{sub 2} films were irradiated with 350 keV Ar{sup +} ions of various fluences up to 10{sup 15}ions/cm{sup 2} at 85 K. During the stepwise amorphization noise density SR spectra of the 1/f noise were taken by applying a correlation measurement technique{sup 2} allowing detection of signals below the thermal noise. It could be shown that the spectral noise density is maximal at the percolation limit whereas the resistance approaches its final value.

  3. Surface morphological evolution and nanoneedle formation of 18Cr-ODS steel by focused ion beam bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Ran, Guang, E-mail: gran@xmu.edu.cn [College of Energy, Xiamen University, Xiamen City, Fujian Province 361102 (China); Chen, Nanjun; Qiang, Rui [College of Energy, Xiamen University, Xiamen City, Fujian Province 361102 (China); Wang, Lumin [College of Energy, Xiamen University, Xiamen City, Fujian Province 361102 (China); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Li, Ning [College of Energy, Xiamen University, Xiamen City, Fujian Province 361102 (China); Lian, Jie, E-mail: lianj@rpi.edu [Department of Mechanical, Aerospace & Nuclear Engineering, Rensselaer Polytechnic Institute, NY (United States)

    2015-08-01

    Highlights: • Morphological evolution of the 18Cr-ODS was studied under intense ion radiation. • The initial surface morphology of the steel significantly affects the nanoneedle formation, and the microstructure of the nanoneedle was characterized by TEM. • The formation mechanism of nano-needle structure of the 18Cr-ODS was discussed. • Surface defects enhance kinetics of surface roughening and pattern formation. - Abstract: Morphological evolution upon intense energetic particle–matter interactions is of fundamental importance for materials utilized in extreme radiation environment, and controlling surface morphology by radiation also provides a new pathway for exploring non-equilibrium process at surface. In this work, surface morphology and microstructural evolution upon low energy ion irradiation of 18Cr-ODS, a candidate structural material for cladding and first wall of future fission and fusion reactors, were investigated by in situ focused Ga{sup +} ion beam/scanning electron microscopy and ex situ transmission electron microscopy. A surface roughening through pore formation, coalescence and eventually nanoneedle formation was induced on 18Cr-ODS steel surface. Cross-section microstructure analysis indicates that the formation of nanoneedle was not a result of grain recrystallization or chemical composition change. Pre-irradiated materials by He{sup +} and Fe{sup +} ions displays enhanced kinetics for surface morphological evolution and lower fluences of focused Ga{sup +} are required for the nanoneedle formation. These results suggest that the surface roughening and morphological evolution of 18Cr-ODS under low energy ion irradiation is an interplay between a curvature-dependent sputtering and defect accumulation near the surface.

  4. Structural Changes in Alloys of the Al-Cu-Mg System Under Ion Bombardment and Shock-Wave Loading

    Science.gov (United States)

    Ovchinnikov, V. V.; Gushchina, N. V.; Romanov, I. Yu.; Kaigorodova, L. I.; Grigor'ev, A. N.; Pavlenko, A. V.; Plokhoi, V. V.

    2017-02-01

    To confirm the hypothesis on the shock-wave nature of long-range effects upon corpuscular irradiation of condensed media presumably caused by emission and propagation of post-cascade shock waves, comparative experiments on ion beam modification and mechanical shock-wave loading of specimens of VD1 and D16 alloys of the Al-Cu-Mg system are performed. Direct analogy between the processes of microstructural change of cold-deformed VD1 and D16 alloys under mechanical shock loading and irradiation by beams of accelerated Ar+ ions (E = 20-40 keV) with low fluences (1015-1016 cm-2) is established. This demonstrates the important role of the dynamic long-range effects that have not yet been considered in classical radiation physics of solids.

  5. Engineering the Activity and Lifetime of Heterogeneous Catalysts for Carbon Nanotube Growth via Substrate Ion Beam Bombardment (Postprint)

    Science.gov (United States)

    2014-07-31

    11,25 and chirality.19,20 CNTs are grown via heterogeneous catalysis using a thin film of catalyst on a wide variety of catalyst supports. Films of...another method in catalysis science to engineer supports to enhance both catalytic activity and lifetime with general implications for heterogeneous ...AFRL-RX-WP-JA-2014-0159 ENGINEERING THE ACTIVITY AND LIFETIME OF HETEROGENEOUS CATALYSTS FOR CARBON NANOTUBE GROWTH VIA SUBSTRATE ION BEAM

  6. Energy-resolved angular distributions and the population partition of excited state Rh atoms ejected from ion bombarded Rh [l brace]001[r brace

    Energy Technology Data Exchange (ETDEWEB)

    He, C.; Postawa, Z.; El-Maazawi, M.; Rosencrance, S.; Garrison, B.J.; Winograd, N. (Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States))

    1994-10-01

    The energy-resolved angular distributions of Rh atoms ejected from Rh [l brace]001[r brace] by bombardment with 5.0 keV Ar[sup +] ions have been measured for the ground state ([ital a] [sup 4][ital F][sub 9/2]) and the two lowest lying excited state ([ital a] [sup 4][ital F][sub 7/2],[ital a] [sup 4][ital F][sub 5/2]). Simultaneous measurements on these electronic states provide us an opportunity to examine the influence of electronic interactions on desorbed particles. The experimental results show that there is a sequential variation in the angular distributions as the excitation energy increases. These variations are attributed to the interaction between the substrate electrons and the excited state atom as it is being ejected from the surface. Since the measurements are performed using multiphoton ionization via a single intermediate state, the population partition among the three lowest states is obtained as well. The excitation probabilities of the [ital a] [sup 4][ital F][sub 7/2] and [ital a] [sup 4][ital F][sub 5/2] states are compared with those predicted from the expression exp([minus][ital A]/[ital av][sub [perpendicular

  7. EBIS-A facility for the studies of X-ray emission from solids bombarded by highly charged ions

    Energy Technology Data Exchange (ETDEWEB)

    Banaś, D., E-mail: d.banas@ujk.edu.pl [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Jabłoński, Ł. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Jagodziński, P. [Department of Physics, Kielce University of Technology, 25-314 Kielce (Poland); Kubala-Kukuś, A.; Sobota, D.; Pajek, M. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland)

    2015-07-01

    We report here on the progress in the X-ray spectroscopy program at the EBIS-A facility installed recently at the Institute of Physics of Jan Kochanowski University in Kielce. In this facility the beams of low-energy highly charged ions (HCI) produced by the Dresden EBIS-A ion source, after extraction and charge-state separation in the double focusing magnet, are directed to the experimental UHV chamber equipped with a 5-axis universal sample manipulator. The X-rays emitted in interaction of the highly charged ions with solids can be measured by an energy dispersive X-ray silicon drift detector (SDD) and/or a wavelength-dispersive X-ray spectrometer (WDS) mounted at the experimental chamber. The surface nanostructures formed by an impact of HCI will be studied by the grazing emission X-ray fluorescence (GEXRF) technique and using a multiprobe surface analysis system based on the X-ray photoelectron spectrometer (XPS) coupled to the UHV chamber of the EBIS-A facility. In this paper a brief description of the facility, X-ray instrumentation and the surface analysis system is given and the first results are presented.

  8. Production Yield of C-H Cluster From Carbon Material Bombarded by MeV Ions%MeV 离子轰击碳样品引起的碳氢团簇产额

    Institute of Scientific and Technical Information of China (English)

    刘坤; 郑涛; 郭猜; 杨江燕; 田继挺; 聂锐; 马宏骥; 丁富荣

    2014-01-01

    利用北京大学2×1.7 MV静电串列加速器产生的1.5 MeV Au2+和Si+束流轰击碳纳米管样品,用二次离子飞行时间质谱方法分析了二次离子成分,通过质量已知的样品的定标,确认了轰击产生的二次离子质量。分析束流轰击后的二次离子产额,发现在此能量下二次离子产额与离子在物质中射程的横向歧离表现出正相关。%Using the time-of-flight secondary ion mass spectrometry method , the production yield of C-H cluster from carbon material bombarded by MeV ions was investigated .In the experiment ,Si+ and Au2+ ions generated by the 2 × 1.7MV tandem accelerator of Peking University were chosen as the primary ion beams .The mass of the secondary ion was calibrated by the sample with known mass .By analyzing the mass spectrum of the secondary ion bombarded by different ions ,it is found that the yield is related to the lateral straggling of ions in the material at this energy region .

  9. Defect Accumulation and Its Effect on Photoluminescence in GaN Bombarded with Low-energy Heavy Ions

    Institute of Scientific and Technical Information of China (English)

    ZhangChonghong; SongYin; DuanJinglai; SunYoumei; YaoCunfeng; MaHongji; NieRui; T.Shibayama; HongChen

    2003-01-01

    Gallium Nitride (GaN) is an important material for the development of novel short-wave-length photonicdevices or high-frequency, high-power electronic devices. Ion implantation/irradiation was proved to be an effective method to modify the physical properties of the material. In the present work, we studied the dependence of damage accumulation on irradiation dose and temperature and the corresponding effects on photolumines cence character of the material. Specimens of GaN (n-type doping, (0001) on axis) were irradiated with 56Fe+

  10. The effects of interfacial interactions between Fe–O and Fe–Si induced by ion-beam bombardment on the magnetic properties of Si-oxide/Fe bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Li, X. [Department of Electrical and Electronic Engineering, The University of Hong Kong (Hong Kong); Lin, K.-W., E-mail: kwlin@dragon.nchu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Liang, H.-T.; Hsu, H.-F. [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Galkin, N.G. [Institute of Automation & Control Processes, FEB RAS, Radio Str. 5, 690041 Vladivostok (Russian Federation); Wroczynskyj, Y. [Department of Physics and Astronomy, University of Manitoba, Winnipeg R3T 2N2 (Canada); Lierop, J. van, E-mail: johan@physics.umanitoba.ca [Department of Physics and Astronomy, University of Manitoba, Winnipeg R3T 2N2 (Canada); Pong, P.W.T., E-mail: ppong@eee.hku.hk [Department of Electrical and Electronic Engineering, The University of Hong Kong (Hong Kong)

    2015-12-15

    Highlights: • Si capping layer was deposited on Fe layer with O{sub 2}/Ar ion beam bombardment. • Structure deformation and grain re-orientation was observed after bombardment. • FeO, Fe{sub 2}O{sub 3}, SiO{sub 2}, and FeSi were formed in the interface, as proved by XPS. • The interface layer resulted in magnetic coercivity enhancement at low temperature. • Fe–O changed to antiferromagnetic at 10 K, establishing exchange coupling with Fe. - Abstract: Si/Fe and SiO{sub 2}/Fe thin-film heterostructures are commonly seen in magnetic multilayer devices, whose magnetic properties are strongly influenced by intermixing at the interfaces. In this paper, Si-oxide/Fe bilayers were formed by depositing Si on Fe with in situ O{sub 2}/Ar ion-beam bombardment during the Si deposition. The surface oxidation conditions were altered by applying different O{sub 2}/Ar ratios (0–41%) in the ion-beam. The surface and cross-sectional morphologies, and the crystalline structures were characterized by transmission electron microscopy. The formation of Fe–O, Fe–Si and Si–O bonds at the interface of the O{sub 2}/Ar ion-beam bombarded Si-oxide/Fe bilayers was evidenced by X-ray photoemission spectra. FeO, Fe{sub 3}O{sub 4} and Fe{sub 2}O{sub 3} at the interface resulted in a marked increase in the magnetic coercivity at low temperatures, as characterized by magnetometry.

  11. Characterization of carbon contamination under ion and hot atom bombardment in a tin-plasma extreme ultraviolet light source

    Energy Technology Data Exchange (ETDEWEB)

    Dolgov, A., E-mail: a.dolgov@utwente.nl [MESA+ Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Lopaev, D. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation); Lee, C.J. [MESA+ Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Zoethout, E. [Dutch Institute for Fundamental Energy Research (DIFFER), Nieuwegein (Netherlands); Medvedev, V. [MESA+ Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Yakushev, O. [Institute for Spectroscopy Russian Academy of Sciences, Moscow (Russian Federation); Bijkerk, F. [MESA+ Institute for Nanotechnology, University of Twente, Enschede (Netherlands)

    2015-10-30

    Highlights: • Carbon film grown during exposure to EUV radiation and high energy ions was studied. • The carbon film is highly resistant to chemical and physical sputtering. • Surface contamination of plasma-facing components is similar to hydrogenated DLC. - Abstract: Molecular contamination of a grazing incidence collector for extreme ultraviolet (EUV) lithography was experimentally studied. A carbon film was found to have grown under irradiation from a pulsed tin plasma discharge. Our studies show that the film is chemically inert and has characteristics that are typical for a hydrogenated amorphous carbon film. It was experimentally observed that the film consists of carbon (∼70 at.%), oxygen (∼20 at.%) and hydrogen (bound to oxygen and carbon), along with a few at.% of tin. Most of the oxygen and hydrogen are most likely present as OH groups, chemically bound to carbon, indicating an important role for adsorbed water during the film formation process. It was observed that the film is predominantly sp{sup 3} hybridized carbon, as is typical for diamond-like carbon. The Raman spectra of the film, under 514 and 264 nm excitation, are typical for hydrogenated diamond-like carbon. Additionally, the lower etch rate and higher energy threshold in chemical ion sputtering in H{sub 2} plasma, compared to magnetron-sputtered carbon films, suggests that the film exhibits diamond-like carbon properties.

  12. Laser fluorescence spectroscopy of zinc neutrals originating from laser-irradiated and ion-bombarded zinc sulfide and zinc surfaces

    Science.gov (United States)

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

    Time-of-flight (TOF) measurements, employing high-resolution laser-induced fluorescence spectroscopy (LFS) as a probe, have been used to measure the yield and velocity distribution of Zn atoms ejected from a ZnS single crystal under irradiation by 308 nm photons. By comparison with the known ion sputtering yield for pure zinc, the absolute yield was determined to be 10 to the 10th power atoms/pulse at a laser fluence of 30 mJ/sq cm. The velocity distribution of the Zn atoms could be fitted by a Maxwell-Boltzmann distribution, having characteristic temperature of approx 2300 K. In addition, Doppler-shift techniques have been combined with TOF measurements in order to separate prompt from delayed emission of ablated atoms, as well as to probe possible molecular or cluster fragmentation. The results obtained suggest the possibility of molecular or cluster emission from ZnS.

  13. Heavy-ion induced desorption yields of amorphous carbon films bombarded with 4.2 MeV/u lead ions

    CERN Document Server

    Mahner, E; Küchler, D; Scrivens, R; Costa Pinto, P; Yin Vallgren, C; Bender, M

    2011-01-01

    During the past decade, intense experimental studies on the heavy-ion induced molecular desorption were performed in several particle accelerator laboratories worldwide in order to understand and overcome large dynamic pressure rises caused by lost beam ions. Different target materials and various coatings were studied for desorption and mitigation techniques were applied to heavy-ion accelerators. For the upgrade of the CERN injector complex, a coating of the Super Proton Synchrotron (SPS) vacuum system with a thin film of amorphous carbon is under study to mitigate the electron cloud effect observed during SPS operation with the nominal proton beam for the Large Hadron Collider (LHC). Since the SPS is also part of the heavy-ion injector chain for LHC, dynamic vacuum studies of amorphous carbon films are important to determine their ion induced desorption yields. At the CERN Heavy Ion Accelerator (LINAC 3), carbon-coated accelerator-type stainless steel vacuum chambers were tested for desorption using 4.2 Me...

  14. Sputtering of Ag under C{sub 60}{sup +} and Ga{sup +} projectile bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Sun, S.; Szakal, C.; Smiley, E.J.; Postawa, Z.; Wucher, A.; Garrison, B.J.; Winograd, N

    2004-06-15

    Cluster ion bombardment often results in large secondary ion yield enhancements relative to atomic ion bombardment. The yields of neutral particles and secondary ions sputtered from a silver surface were investigated through experiments and molecular dynamics (MD) computer simulations. The results show that the neutral Ag yield produced by 15 keV C{sub 60}{sup +} bombardment is 5.6-fold higher than that found for 15 keV Ga{sup +} bombardment, which is in agreement with simulations. The enhancement effect is observed to be about the same for both neutral species and their corresponding secondary ions. Experimental results also indicate that the Ag neutral species produced by C{sub 60}{sup +} bombardment have emission velocity distributions that maximize at much lower values than those observed by Ga{sup +} bombardment, suggesting the presence of non-linear collision cascades.

  15. Illusory Late Heavy Bombardments.

    Science.gov (United States)

    Boehnke, Patrick; Harrison, T Mark

    2016-09-27

    The Late Heavy Bombardment (LHB), a hypothesized impact spike at ∼3.9 Ga, is one of the major scientific concepts to emerge from Apollo-era lunar exploration. A significant portion of the evidence for the existence of the LHB comes from histograms of (40)Ar/(39)Ar "plateau" ages (i.e., regions selected on the basis of apparent isochroneity). However, due to lunar magmatism and overprinting from subsequent impact events, virtually all Apollo-era samples show evidence for (40)Ar/(39)Ar age spectrum disturbances, leaving open the possibility that partial (40)Ar* resetting could bias interpretation of bombardment histories due to plateaus yielding misleadingly young ages. We examine this possibility through a physical model of (40)Ar* diffusion in Apollo samples and test the uniqueness of the impact histories obtained by inverting plateau age histograms. Our results show that plateau histograms tend to yield age peaks, even in those cases where the input impact curve did not contain such a spike, in part due to the episodic nature of lunar crust or parent body formation. Restated, monotonically declining impact histories yield apparent age peaks that could be misinterpreted as LHB-type events. We further conclude that the assignment of apparent (40)Ar/(39)Ar plateau ages bears an undesirably high degree of subjectivity. When compounded by inappropriate interpretations of histograms constructed from plateau ages, interpretation of apparent, but illusory, impact spikes is likely.

  16. Modification of thin oxide films on Be, Si, Al, Ti, Zr, and W under bombardment by He+ and Ar+ ion beams with a broad energy spectrum

    NARCIS (Netherlands)

    Volkov, N. V.

    2011-01-01

    Data on the distribution of Be, Al, Ti, Fe, Cu, Zr, Mo, and W atoms implanted in oxide film on metal substrates by ion mixing under the action of He+ and Ar+ ion beams with a broad energy spectrum, with average energy of 10 keV, and with radiation doses up to 1 x 10(21) ion/cm(2) are presented. It i

  17. Anomalous behavior in temporal evolution of ripple wavelength under medium energy Ar{sup +}-ion bombardment on Si: A case of initial wavelength selection

    Energy Technology Data Exchange (ETDEWEB)

    Garg, Sandeep Kumar [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Cuerno, Rodolfo [Departamento de Matematicas and Grupo Interdisciplinar de Sistemas Complejos (GISC), Universidad Carlos III de Madrid, 28911 Leganes (Spain); Kanjilal, Dinakar [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Som, Tapobrata, E-mail: tsom@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India)

    2016-06-14

    We have studied the early stage dynamics of ripple patterns on Si surfaces, in the fluence range of 1–3 × 10{sup 18} ions cm{sup −2}, as induced by medium energy Ar{sup +}-ion irradiation at room temperature. Under our experimental conditions, the ripple evolution is found to be in the linear regime, while a clear decreasing trend in the ripple wavelength is observed up to a certain time (fluence). Numerical simulations of a continuum model of ion-sputtered surfaces suggest that this anomalous behavior is due to the relaxation of the surface features of the experimental pristine surface during the initial stage of pattern formation. The observation of this hitherto unobserved behavior of the ripple wavelength seems to have been enabled by the use of medium energy ions, where the ripple wavelengths are found to be order(s) of magnitude larger than those at lower ion energies.

  18. Self-terminated etching of GaN with a high selectivity over AlGaN under inductively coupled Cl2/N2/O2 plasma with a low-energy ion bombardment

    Science.gov (United States)

    Zhong, Yaozong; Zhou, Yu; Gao, Hongwei; Dai, Shujun; He, Junlei; Feng, Meixin; Sun, Qian; Zhang, Jijun; Zhao, Yanfei; DingSun, An; Yang, Hui

    2017-10-01

    Etching of GaN/AlGaN heterostructure by O-containing inductively coupled Cl2/N2 plasma with a low-energy ion bombardment can be self-terminated at the surface of the AlGaN layer. The estimated etching rates of GaN and AlGaN were 42 and 0.6 nm/min, respectively, giving a selective etching ratio of 70:1. To study the mechanism of the etching self-termination, detailed characterization and analyses were carried out, including X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). It was found that in the presence of oxygen, the top surface of the AlGaN layer was converted into a thin film of (Al,Ga)Ox with a high bonding energy, which effectively prevented the underlying atoms from a further etching, resulting in a nearly self-terminated etching. This technique enables a uniform and reproducible fabrication process for enhancement-mode high electron mobility transistors with a p-GaN gate.

  19. Tribological properties of nc-TiC/a-C : H coatings prepared by magnetron sputtering at low and high ion bombardment of the growing film

    NARCIS (Netherlands)

    Souček, Pavel; Schmidtová, Tereza; Buršíková, Vilma; Vašina, Petr; Pei, Y.T.; Hosson, J.Th.M. De; Caha, Ondřej; Peřina, Vratislav; Mikšová, Romana; Malinský, Petr

    2014-01-01

    Two series of nc-TiC/a-C:H coatings were deposited by a hybrid PVD–PECVD process of titanium sputtering in argon/acetylene atmosphere at two configurations of magnetic field resulting in different impinging ion fluxes on the growing film. The composition of the coatings was varied by changing the

  20. Tribological properties of nc-TiC/a-C : H coatings prepared by magnetron sputtering at low and high ion bombardment of the growing film

    NARCIS (Netherlands)

    Souček, Pavel; Schmidtová, Tereza; Buršíková, Vilma; Vašina, Petr; Pei, Y.T.; Hosson, J.Th.M. De; Caha, Ondřej; Peřina, Vratislav; Mikšová, Romana; Malinský, Petr

    2014-01-01

    Two series of nc-TiC/a-C:H coatings were deposited by a hybrid PVD–PECVD process of titanium sputtering in argon/acetylene atmosphere at two configurations of magnetic field resulting in different impinging ion fluxes on the growing film. The composition of the coatings was varied by changing the ac

  1. Effect of ion bombardment on the structural and optical properties of TiO{sub 2} thin films deposited from oxygen/titanium tetraisopropoxide inductively coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Li, D. [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Carette, M.; Granier, A.; Landesman, J.P. [Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, UMR CNRS 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France); Goullet, A., E-mail: antoine.goullet@univ-nantes.fr [Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, UMR CNRS 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France)

    2015-08-31

    Titanium dioxide films were deposited on silicon substrates from oxygen/titanium tetraisopropoxide inductively coupled radiofrequency plasmas in a helicon reactor operated at low temperature (< 150 °C) and low pressure (0.4 Pa). The effect of the ion energy (E{sub i}), varied in the 15–175 eV range, on the morphology, microstructure and optical properties of the films is investigated. Scanning electron microscopy (SEM) shows that at low energy (E{sub i} = 15 eV), the film exhibits a columnar morphology consisting of a bottom dense layer, an intermediate gradient layer and a top roughness layer. Increasing the ion energy results in more homogeneous films along the growth direction as confirmed by the in-situ kinetic ellipsometry measurements and post deposition spectroscopic ellipsometry data analysis. In addition, the atomic force microscopy (AFM) measurements reveal that the film top surface becomes smoother as E{sub i} is increased. X-ray diffraction (XRD) diagrams show that only anatase is identified in the film deposited at 15 eV, whereas the complete phase transformation from anatase to rutile occurs at E{sub i} = 75 eV. These results are in good agreement with the Fourier transform infrared spectroscopy (FTIR) spectra which also show that the hydroxyl groups absorbed in the films deposited at 15 eV, are greatly decreased for E{sub i} ≥ 45 eV. Suitable structural models combined with the Tauc–Lorentz dispersion law have been found to accurately fit the spectroscopic ellipsometry experimental data. The results in good agreement with SEM and AFM measurements are also consistent with the structural properties evidenced by XRD and FTIR. The refractive index (n) can be increased significantly by increasing the ion energy from 15 eV to 75 eV, reaching a value of 2.49 at 1.96 eV. Upon increasing the ion energy above 75 eV n is shown to decrease due to micropores which are formed in the films. - Highlights: • TiO{sub 2} thin films deposited in inductively

  2. State-selective energy and angular resolved detection of neutral species ejected from keV ion bombarded C{sub 6}H{sub 6}/Ag{l_brace}1 1 1{r_brace}

    Energy Technology Data Exchange (ETDEWEB)

    Vandeweert, E.; Meserole, C.A.; Sostarecz, A.; Dou, Y.; Winograd, N. E-mail: nxw@psu.edunxw@psuvm.psu.edu; Postawa, Z

    2000-04-01

    We investigated the desorption of neutral benzene (C{sub 6}H{sub 6}) molecules and silver atoms from C{sub 6}H{sub 6}/Ag{l_brace}1 1 1{r_brace} upon bombardment by 8 keV Ar{sup +} ions. Using state-selective resonant ionization spectroscopy, substrate atoms sputtered in the ground and a high-lying metastable state, and ground-state and vibrationally excited molecules could be probed separately. The silver atom yield, kinetic energy and polar angle distributions were found to be modified upon benzene dosing. From these results, it was inferred that a large fraction of the metastable silver atoms de-excite during collisions with adsorbates. Also the ejection of benzene molecules depends strongly both on the internal energy of the molecules and the degree of coverage of the Ag surface. Up to monolayer thickness, the benzene molecules are mainly ejected during collisions with departing substrate particles. Molecules with higher internal energy leave the surface with a distribution shifted towards higher kinetic energies. At multi-layer coverages, a slow desorption mechanism becomes dominant. It is suggested that only benzene molecules vibrationally excited near the benzene-vacuum interface can survive the ejection process without de-excitation.

  3. Determination of optical damage cross-sections and volumes surrounding ion bombardment tracks in GaAs using coherent acoustic phonon spectroscopy

    Science.gov (United States)

    Steigerwald, A.; Hmelo, A. B.; Varga, K.; Feldman, L. C.; Tolk, N.

    2012-07-01

    We report the results of coherent acoustic phonon spectroscopy analysis of band-edge optical modification of GaAs irradiated with 400 keV Ne++ for doses between 1011-1013 cm-2. We relate this optical modification to the structural damage density as predicted by simulation and verified by ion channeling analysis. Crystal damage is observed to cause optical modification that reduces the amplitude of the optoacoustic signal. The depth-dependent nature of the optoacoustic measurement allows us to determine optical damage cross-sections along the ion track, which are found to vary as a function of position along the track. Unexpectedly, we find that this optical modification is primarily dependent on the structural damage density and insensitive to the specific defect configuration along the ion track, suggesting that a simple model of defect density along the track is sufficient to characterize the observed optical changes. The extent of optical modification is strongly probe frequency-dependent as the frequency is detuned from the GaAs band edge. As determined from the experimental measurements, the spatial extent of optical modification exceeds the spatial extent of the structural disorder by an order of magnitude.

  4. Reactive magnetron sputtering of highly (001)-textured WS2-x films: Influence of Ne+, Ar+ and Xe+ ion bombardment on the film growth

    Science.gov (United States)

    Ellmer, K.; Seeger, S.; Sieber, I.; Bohne, W.; Röhrich, J.; Strub, E.; Mientus, R.

    2006-02-01

    Tungsten disulfide WS2 is a layer-type semi-conductor with an energy band gap and an absorption coefficient making it suitable as an absorber for thin film solar cells. In the article [1] WS2-x films were pre-pared by reactive magnetron sputtering from a metallic tungsten target in Ar-H2S atmospheres.The cover figure shows in situ energy-dispersive X-ray diffraction patterns for films deposited at different substrate potentials, i.e. for deposition conditions with ion assistance at different ion energies. These spectra and the corresponding SEM photographs of the film morphology show the strong influence of the ion energy on the film growth. The crystallographic struc-ture of WS2-x is shown between the two SEM pictures.The first author, Klaus Ellmer, is working at the Hahn-Meitner-Institut Berlin, Dept. of Solar Energy Research. His research fields are thin film deposition by reactive magnetron sputtering for solar cells, plasma characterization, in situ energy-dispersive X-ray diffraction and electronic transport in transpar-ent conductive oxides.

  5. Independent cross-sections of alkali isotopes produced in various targets bombarded by $^{12}C$ and $^{18}O$ ions up to 77 MeV/amu

    CERN Document Server

    De Saint-Simon, M; Coc, A; Epherre-Rey-Campagnolle, Marcelle; Guimbal, P; Haan, S; Langevin, M; Müller, A C; Thibault, C; Touchard, F

    1982-01-01

    The authors report on an online mass-spectrometric study of the isotopic distributions of nuclear reaction products. The two purposes of this experiment are the investigation of a particular aspect of reaction-mechanisms and the study of the possibility for exotic-nuclei production. The measurements have been carried out with the 86 MeV/amu /sup 12/C and /sup 18/O beams of the synchrocyclotron SC (CERN). By degradation in different sets of graphite slabs, three different energies: 13, 27 and 77 MeV/amu have been chosen. Due to the chemical selectivity for the alkali elements of the device, the isotopic distributions of Li, Na, K, Rb, Cs and Fr were measured in four targets: C, Nb, Ta and U. The independent yields obtained by direct ion counting are converted in cross-sections using a calibration of T. Lund et al.

  6. Effect of the ion-beam bombardment and annealing temperature on sol-gel derived yttrium aluminum oxide film as liquid crystal alignment layer

    Science.gov (United States)

    Jeong, Hae-Chang; Heo, Gi-Seok; Kim, Eun-Mi; Lee, Ju Hwan; Han, Jeong-Min; Seo, Dae-Shik

    2017-02-01

    We demonstrated a homogeneous liquid-crystal (LC) alignment state on yttrium aluminum oxide (YAlO) films, where the alignment was induced by ion-beam (IB) irradiation. Topographical analysis was performed by atomic force microscopy as a function of annealing temperature. Higher annealing temperatures yielded a smoother surface, accompanied by reduced light scattering. Transparency in the visible region increased on the surface fabricated at higher annealing temperatures. LC alignment mechanism was determined by X-ray diffraction (XRD) analysis. Moreover, IB-irradiated YAlO films annealed at temperatures greater than 200 °C exhibited good thermal stability and low capacitance-voltage hysteresis. The IB-irradiated YAlO films are suitable as alternative alignment layers in advanced LC display applications.

  7. DLTS study of deep centers created by Ar-ion bombardment in n- and p-type MBE AlGaAs

    Science.gov (United States)

    Kaniewska, M.; Sadowski, J.; Guziewicz, M.

    2004-07-01

    The thermal emission rate of dominant traps in molecular beam epitaxial n- and p-type AlGaAs subjected to Ar-ion beam etching has been studied by deep level transient spectroscopy. Emission signatures were determined and compared with results obtained by other authors for irradiation induced and grown-in defects in GaAs and AlGaAs. The most significant result of this study is the observation that the process-induced defects in n- as well as p-type AlGaAs exhibit emission signatures, which are characteristic of native defects found in GaAs. The effect is discussed in terms of a compensation effect and related band bending.

  8. Simulation of Carbon Nanotube Welding through Ar bombardment

    CERN Document Server

    Kucukkal, Mustafa U

    2014-01-01

    Single-walled carbon nanotubes show promise as nanoscale transistors, for nanocomputing applications. This use will require appropriate methods for creating electrical connections between distinct nanotubes, analogous to welding of metallic wires at larger length scales, but methods for performing nanoscale chemical welding are not yet sufficiently understood. This study examined the effect of Ar bombardment on the junction of two crossed single-walled carbon nanotubes, to understand the value and limitations of this method for generating connections between nanotubes. A geometric criterion was used to assess the quality of the junctions formed, with the goal of identifying the most productive conditions for experimental ion bombardment. In particular, the effects of nanotube chirality, Ar impact kinetic energy, impact particle flux and fluence, and annealing temperature were considered. The most productive bombardment conditions, leading to the most crosslinking of the tubes with the smallest loss of graphit...

  9. 用于等离子体离子辐照的新型阶梯型脉冲高压电路研制%Novel Circuit Producing Pulsed High Voltage with Discrete Steps for Ion Bombardment in Plasma Immersion

    Institute of Scientific and Technical Information of China (English)

    石经纬; 田修波; 巩春志; 杨士勤

    2011-01-01

    为满足等离子体离子辐照和复合表面改性处理技术的发展,提出了基于Marx发生器,通过调节驱动信号延时,实现放电IGBT开关不同时导通,从而获得阶梯型脉冲高压输出的电路设计思想,并验证了其可行性.试验结果显示,该电路可输出脉冲峰值电压10 kV,峰值电流30 A,脉冲宽度3~30μs,脉冲频率20~500 Hz,最大电压阶数10阶的高压脉冲.1个原边、10个副边结构的驱动高压隔离变压器及延时驱动电路结构紧凑,抗干扰能力强.IGBT驱动反向偏置脉冲电压能够满足IGBT快速关断和过流保护的要求.等离子体负载下电路特性测试结果表明,该电路能够适应实际的工作环境,为复合处理技术的发展提供技术支持.该电路结构通过Marx单元叠加可以拓展到更高的脉冲电压输出.%A novel circuit which is capable of producing pulsed high voltage with discrete steps based on Marx generator has been developed for ion bombardment in plasma immersion, and it is realized by means of each discharge IG-BT switching on at different time by adjusting the delay time of drive signals. A compact and robust circuit is designed, using a high-voltage isolation transformer with one primary winding and ten secondary windings for control signal and designed delay drive unit, to meet the requirements of rapidity of switch off and overcurrent protection of IGBT. A pulsed high voltage with amplitude of 10kV, peak current of 30A, pulse width of 3~30 μs, frequency of 20~500 Hz and voltage steps of 10 are achieved. The developed circuit with several kinds of output voltage waveforms is applied to the plasma load with high reliability, and possesses the practicability for ion bombardment or hy-. Brid surface modification in plasma immersion mode. The higher pulse voltage may be achieved using more Marx link with the same control mode for wide application.

  10. Surface Modification by Oxygen Ion Bombardment and Wettibility Enhancement of Polythylene Terephthalate%氧离子束工作压强对PET表面化学键结构及润湿性能的影响

    Institute of Scientific and Technical Information of China (English)

    张立娜; 丁万昱; 巨东英; 柴卫平

    2013-01-01

    利用直流离子源产生氧离子束并在室温条件下与PET表面进行相互作用.通过X光电子能谱仪、接触角测试仪等表征技术,分析氧离子束工作压强对PET表面化学组分、化学键结构,以及对极性H2O分子液体的静态接触角等性能的影响.研究结果表明,当氧离子束与PET表面相互作用时,PET表面的C-O、C-H键首先被破坏,氧离子与C-垂悬键结合形成C-O或C=O极性键.随着氧离子束工作压强的增加,更多的氧离子与PET表面相互作用,导致处理后的PET表面含氧量增加,C=O/C-O比例增加,对极性H2O分子液体侵润性增强.当氧离子束工作压强增加至0.9Pa时,处理后的PET表面氧元素相对百分比含量由纯PET的28%增加至37%(原子比),C=O/C-O键比例由纯PET的1.13∶1增加至2.85:1,而极性H2O分子液体的静态接触角由纯PET的55.3°减低至7.0°,接近于完全润湿.上述结果表明,氧离子束是一种有效调节PET表面化学组分、化学键结构、及表面性质的简单而有效的方法.%The surfaces of polythylene terephthalate (PET) were modified by oxygen ion bombardment at room temperature to improve the surface wettibility.The surface modified PET was characterized with X-ray photoelectron spectroscopy.The impacts of the surface modification conditions,including the pressure,incident angle of oxygen ion beam,and substrate temperature,on the PET wettibility were evaluated.The results show that the pressure of the oxygen ion beam significantly affects the microstructures,bond breaking,contents and wettibility of the PET.For instance,as the pressure increased,the oxygen content and ratio of C =O/C-O on the PET surfaces increased,and the contact angle of polar liquid like water decreased possibly because an increased oxygen ions reacted with surfaces.At 0.9 Pa,the surface oxygen content increased from 28% to 37% (at) ; the ratio of C =O to C-O bonds increased from 1.13∶1 to 2.85 ∶ 1 ; and the water

  11. Nanostructuring of Ta{sub 2}O{sub 5} surfaces by low energy Ar{sup +} bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Benito, Noelia; Palacio, Carlos, E-mail: carlos.palacio@uam.es

    2015-10-01

    Graphical abstract: - Highlights: • Ar{sup +} bombardment of Ta{sub 2}O{sub 5} surfaces leads to the formation of an altered layer where the composition is different from that of the bulk. • Ar{sup +} bombardment of Ta{sub 2}O{sub 5} surfaces leads to the formation of short-range hexagonal order nanostructures. • The height of the nanostructures is equal to the thickness of the altered layer produced during bombardment. • There is a close relationship between the nanostructuring of the surface and the altered layer formed during bombardment. - Abstract: The surface modifications undergoing on a Ta{sub 2}O{sub 5} surface bombarded with Ar{sup +} have been studied using surface analysis techniques (XPS, ARXPS and AFM). It has been observed that ion bombardment produces an altered layer composed of Ta suboxides as a consequence of the preferential sputtering of oxygen atoms. ARXPS measurements carried out on the bombarded surfaces can be explained using a model in which the altered layer consist of suboxide islands, with coverage 85% and thickness 2.88 nm. Moreover, AFM measurements show that ion bombardment leads to the formation of short-range hexagonal order nanostructures with characteristic parameters fully consistent with those found in ARXPS for the island model, therefore indicating the close relationship between the nanostructuring of the surface and the altered layer formed during bombardment.

  12. Bombardment-induced segregation and redistribution

    Energy Technology Data Exchange (ETDEWEB)

    Lam, N.Q.; Wiedersich, H.

    1986-04-01

    During ion bombardment, a number of processes can alter the compositional distribution and microstructure in near-surface regions of alloys. The relative importance of each process depends principally on the target composition, temperature, and ion characteristics. In addition to displacement mixing leading to a randomization of atomic locations, and preferential loss of alloying elements by sputtering, which are dominant at relatively low temperatures, several thermally-activated processes, including radiation-enhanced diffusion, radiation-induced segregation and Gibbsian adsorption, also play important roles. At elevated temperatures, nonequilibrium point defects induced by ion impacts become mobile and tend to anneal out by recombination and diffusion to extended sinks, such as dislocations, grain boundaries and free surfaces. The high defect concentrations, far exceeding the thermodynamic equilbrium values, can enhance diffusion-controlled processes, while persistent defect fluxes, originating from the spatial non-uniformity in defect production and annihilation, give rise to local redistribution of alloy constituents because of radiation-induced segregation. Moreover, when the alloy is maintained at high temperature, Gibbsian adsorption, driven by the reduction in free energy of the system, occurs even without irradiation; it involves a compositional perturbation in a few atom layers near the alloy surface. The combination of these processes leads to the complex development of a compositionally-modified layer in the subsurface region. In the present paper, selected examples of these different phenomena and their synergistic effects on the evolution of the near-surface compositions of alloys during sputtering and ion implantation at elevated temperatures are discussed. 74 refs., 7 figs., 1 tab.

  13. Geologic constraints on Rhea's bombardment mass

    Science.gov (United States)

    Leight, Clarissa; Rivera-Valentin, Edgard G.

    2016-10-01

    The mid-sized moons (MSMs) of Saturn display a peculiar set of properties that indicate the system may have been altered early in its history. The MSMs have a large spread in silicate content and diverse inferred thermal and physical histories that, unlike the Galilean satellites, do not demonstrate a trend with semi-major axis or size, which would indicate orbital evolution was a significant driver of their thermal histories. Rather, these features may indicate a significant role for impact-induced thermal and physical evolution. Geophysical properties along with measured crater counts can be used to constrain the bombardment history of the MSMs. Here we apply a fully three-dimensional Monte Carlo cratering model along with Rhea's measured cratering to provide constraints on the cumulative bombardment mass (Mb) experienced by the moon. The classic Nice model estimates Rhea's cumulative bombardment mass (MNice) to be 8.4x10^19 kg; our preliminary results suggest Rhea experienced a bombardment of 0.05 MNice < Mb < 0.06 MNice. Results agree well with similar constraints from Iapetus and provide further support to the Nice II model, which suggests a reduced bombardment for the outer solar system due to the planetesimals having higher kinetic energies. The inferred Mb and typical impact characteristics suggests Rhea may avoid runaway differentiation.

  14. The Effect of Diffusion Barrier and Bombardment on Adhesive Strength of CuCr Alloy Films

    Institute of Scientific and Technical Information of China (English)

    WANGJian-feng; SONGZhong-xiao; XUKe-wei; WANGYuan

    2004-01-01

    A novel co-sputtering method that combined magnetron sputtering (MS) with ion beam sputtering (IBS) was used to fabricate CuCr alloy films without breaking vacuum after depositing diffusion barrier with IBS. Different bombardment energies were used to improve the comprehensive properties of Cu alloy film. The results indicated that the effects of diffusion barriers and bombardment energy on adhesive strength could be evaluated by a rolling contact fatigue adhesion test. Diffusion barrier can enhance the adhesive strength, and the adhesion of CuCr/CrN was higher than that of CuCr/TiN. When bombarding energy was higher, the adhesive strength of CuCr/TiN films was higher due to the broader transition zone.

  15. Effect of Ar bombardment on the electrical and optical properties of low-density polyethylene films

    Indian Academy of Sciences (India)

    2016-11-01

    The influence of low-energy Ar ion beam irradiation on both electrical and optical properties of low-density polyethylene (LDPE) films is presented. The polymer films were bombarded with 320 keV Ar ions with fuences up to $1 \\times 10^{15}$ cm$^{−2}$. Electrical properties of LDPE films were measured and the effect of ion bombardment on the DC conductivity, dielectric constant and loss was studied. Optically, the energy gap, the Urbach’s energy and the number of carbon atoms in a cluster were estimated for all polymer samples using theUV–Vis spectrophotometry technique. The obtained results showed slight enhancement in the conductivity and dielectric parameters due to the increase in ion fluence. Meanwhile, the energy gap and the Urbach’s energyvalues showed significant decrease by increasing the Ar ion fluence. It was found that the ion bombardment induced chain scission in the polymer chain causing some carbonization. An increase in the number of carbonatoms per cluster was also observed.

  16. Chronology and Sources of Lunar Impact Bombardment

    CERN Document Server

    Ćuk, Matija

    2011-01-01

    The Moon has suffered intense impact bombardment ending at 3.9 Gyr ago, and this bombardment probably affected all of the inner Solar System. Basin magnetization signatures and lunar crater size-distributions indicate that the last episode of bombardment at about 3.85 Gyr ago was less extensive than previously thought. We explore the contribution of the primordial Mars-crosser population to early lunar bombardment. We find that Mars-crosser population initially decays with a 80-Myr half-life, with the long tail of survivors clustering on temporarily non-Mars-crossing orbits between 1.8 and 2 AU. These survivors decay with half-life of about 600 Myr and are progenitors of the extant Hungaria asteroid group in the same region. We estimate the primordial Mars-crosser population contained about 0.01-0.02 Earth masses. Such initial population is consistent with no lunar basins forming after 3.8 Gya and the amount of mass in the Hungaria group. As they survive longer and in greater numbers than other primordial pop...

  17. Changes of Dust Grain Properties Under Particle Bombardment

    Science.gov (United States)

    Pavlů, J.; Richterová, I.; Fujita, D.; Šafránková, J.; Němeček, Z.

    2008-09-01

    The dust in space environments is exposed to particle bombardment. Under an impact of ions, electrons, and photons, the charge of a particular grain changes and, in some cases, the grain structure can be modified. The present study deals with spherical melamine formaldehyde resin grains that are frequently used in many dusty plasmas and microgravity experiments and it concentrates on the influence of the electron beam impact on a grain size. We have performed series of experiments based on the SEM technique. Our investigation has shown that the electron impact can cause a significant increase of the grain size. We discuss changes of material properties and consequences for its applications in laboratory and space experiments.

  18. Fast atom bombardment tandem mass spectrometry of carotenoids

    Energy Technology Data Exchange (ETDEWEB)

    van Breeman, R.B. [Univ. of Illinois, Chicago, IL (United States); Schmitz, H.H.; Schwartz, S.J. [North Carolina State Univ., Raleigh, NC (United States)

    1995-02-01

    Positive ion fast atom bombardment (FAB) tandem mass spectrometry (MS-MS) using a double-focusing mass spectrometer with linked scanning at constant B/E and high-energy collisionally activated dissociation (CAD) was used to differentiate 17 different cartenoids, including {beta}-apo-8{prime}- carotenal, astaxanthin, {alpha}-carotene, {beta}-carotene, {gamma}-carotene, {zeta}-carotene, canthaxanthin, {beta}-cryptoxanthin, isozeaxanthin bis (pelargonate), neoxanthin, neurosporene, nonaprene, lutein, lycopene, phytoene, phytofluene, and zeaxanthin. The carotenoids were either synthetic or isolated from plant tissues. The use of FAB ionization minimized degradation or rearrangement of the carotenoid structures due to the inherent thermal instability generally ascribed to these compounds. Instead of protonated molecules, both polar xanthophylls and nonpolar carotenes formed molecular ions, M{sup {center_dot}+}, during FAB ionization. Following collisionally activated dissociation, fragment ions of selected molecular ion precursors showed structural features indicative of the presence of hydroxyl groups, ring systems, ester groups, and aldehyde groups and the extent of aliphatic polyene conjugation. The fragmentation patterns observed in the mass spectra herein may be used as a reference for the structural determination of carotenoids isolated from plant and animal tissues. 18 refs., 4 figs.

  19. Room temperature deposition of high figure of merit Al-doped zinc oxide by pulsed-direct current magnetron sputtering: Influence of energetic negative ion bombardment on film's optoelectronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Fumagalli, F., E-mail: francesco.fumagalli@iit.it; Martí-Rujas, J., E-mail: javier.rujas@iit.it; Di Fonzo, F., E-mail: fabio.difonzo@iit.it

    2014-10-31

    Aluminum-doped zinc oxide is regarded as a promising indium-free transparent conductive oxide for photovoltaic and transparent electronics. In this study high transmittance (up to 90,6%) and low resistivity (down to 8,4°1{sup −4} Ω cm) AZO films were fabricated at room temperature on thermoplastic and soda-lime glass substrates by means of pulsed-DC magnetron sputtering in argon gas. Morphological, optical and electrical film properties were characterized using scanning electron microscopy, UV–vis–nIR photo-spectrometer, X-ray spectroscopy and four probes method. Optimal deposition conditions were found to be strongly related to substrate position. The dependence of functional properties on substrate off-axis position was investigated and correlated to the angular distributions of negative ions fluxes emerging from the plasma discharge. Figure of merit as high as 2,15 ± 0,14 Ω{sup −1} were obtained outside the negative oxygen ions confinement region. Combination of high quality AZO films deposited on flexible polymers substrates by means of a solid and scalable fabrication technique is of interest for application in cost-effective optoelectrical devices, organic photovoltaics and polymer based electronics. - Highlights: • High figure of merit transparent conductive oxide's deposited at room temperature. • High transmittance and low resistivity obtained on thermoplastic substrates. • Competitive optoelectrical properties compared to high temperature deposition. • Negative ion fluxes confinement influence structural and optoelectrical properties. • Easily adaptable for scaled-up low temperature AZO film deposition installations.

  20. On-line analysis of penicillin blood levels in the live rat by combined microdialysis/fast-atom bombardment mass spectrometry.

    OpenAIRE

    Caprioli, R.M.; Lin, S. N.

    1990-01-01

    The combination of microdialysis and fast-atom bombardment mass spectrometry has been used to follow the pharmacokinetics of penicillin G directly in the blood-stream of a live rat. After the intramuscular injection of the antibiotic, the blood dialysate was allowed to flow into the mass spectrometer via the continuous-flow/fast-atom bombardment interface. Tandem mass spectrometry provided the means for isolating and recording the ion fragments produced from the drug as the dialysate was expo...

  1. Sputtering of solid deuterium by He-ions

    DEFF Research Database (Denmark)

    Schou, Jørgen; Stenum, B.; Pedrys, R.

    2001-01-01

    Sputtering of solid deuterium by bombardment of 3He+ and 4He+ ions was studied. Some features are similar to hydrogen ion bombardment of solid deuterium, but for the He-ions a significant contribution of elastic processes to the total yield can be identified. The thin-film enhancement is more...... pronounced than that for hydrogen projectiles in the same energy range....

  2. Ion emission in solids bombarded with Au{sub n}{sup +} (n = 1 - 9) clusters accelerated within the 0.15 - 1.25 MeV energy range; Emission ionique des solides a l'impact d'agregats Au{sub n}{sup +} (n=1-9) acceleres entre 0,15 et 1,25 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Wehbe, Nimer [Universite Claude Bernard Lyon-I, 43 boulevard du 11 Novembre 1918, 69622 Villeurbanne cedex (France)

    2006-06-15

    This experimental work is devoted to the study of the ion emission in solids at the impact of gold clusters of energies within 0.15 to 1.25 MeV range. The physics of ion-solid collisions and the theoretical models of sputtering of solids under ion bombardment are presented in the first chapter. The chapter no. 2 deals with the description of the experimental setup. The study of a gold target allowed to evidence the role of the size and energy of the clusters in determining the emission intensity and the mass distribution of the ions. The 4. chapter gives results from the study of cesium iodide in which the intense emission of CsI clusters could be investigated quantitatively due to multiplicity measurements. Finally, the chapter no. 5 was devoted to the study of a biologic molecule, the phenylalanine, and of a pesticide molecule, chlorosulfuron. This work evidenced the importance of clusters for surface analyses by mass spectrometry.

  3. Surface layer evolution caused by the bombardment with ionized metal vapor

    Energy Technology Data Exchange (ETDEWEB)

    Döbeli, M., E-mail: doebeli@phys.ethz.ch [Ion Beam Physics, ETH Zurich, Schafmattstrasse 20, CH-8093 Zurich (Switzerland); Dommann, A.; Maeder, X.; Neels, A. [Centre Suisse d’Electronique et de Microtechnique CSEM SA, Rue Jaquet-Droz 1, CH-2002 Neuchâtel (Switzerland); Passerone, D. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Rudigier, H. [OC Oerlikon Balzers AG, Iramali 18, LI-9496 Balzers (Liechtenstein); Scopece, D. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Widrig, B.; Ramm, J. [OC Oerlikon Balzers AG, Iramali 18, LI-9496 Balzers (Liechtenstein)

    2014-08-01

    The evolution of the composition of tungsten carbide and silicon surfaces initiated by the bombardment with Zr and Cr ions has been investigated as a function of the substrate bias voltage. Surface composition profiles were measured by Rutherford backscattering and have been compared with the results obtained by the TRIDYN simulation program. It is found that the general dependence of film thickness on substrate bias is satisfactorily reproduced by this model. Deviations between experiment and simulation are attributed to possible partial oxidation of the surface or uncertainties in the charge state distribution of metal ions. The results confirm that TRIDYN facilitates the predictability of the nucleation of metallic vapor at substrate surfaces.

  4. Carbon cluster diagnostics-I: Direct Recoil Spectroscopy (DRS) of Ar+ and Kr+ bombarded graphite

    CERN Document Server

    Ahmad, Shoaib; Qayyum, A; Ahmad, B; Bahar, K; Arshed, W

    2016-01-01

    Measurements of the energy spectra of multiply charged positive and negative carbon ions recoiling from graphite surface under 100 and 150 keV argon and krypton ion bombardment are presented. With the energy spectrometer set at recoil angle of 79.5 degrees, direct recoil (DR) peaks have been observed with singly as well as multiply charged carbon ions , where n = 1 to 6. These monatomic and cluster ions have been observed recoiling with the characteristic recoil energy E(DR) . We have observed sharp DR peaks. A collimated projectile beam with small divergence is supplemented with a similar collimation before the energy analyzer to reduce the background of sputtered ions due to scattered projectiles.

  5. Electron bombardment of water adsorbed on Zr(0001) surfaces

    CERN Document Server

    Ankrah, S; Ramsier, R D

    2003-01-01

    A study of the effects of electron bombardment on water adsorbed on Zr(0001) is reported. Zirconium surfaces are dosed with isotopic water mixtures at 160 K followed by electron bombardment (485 eV). The system is then probed by low energy electron diffraction, temperature programmed desorption (TPD) and Auger electron spectroscopy (AES). No evidence is found that would indicate preferential mixing of hydrogen from the bulk with isotopic water dissociation products during TPD. However, electron bombardment results in the sharpening of a hydrogen/deuterium desorption peak near 320 K and the production of water near 730 K at low water exposures. In addition, although water does not oxidize Zr(0001) thermally, electron bombardment of adsorbed water induces a shift of about 2 eV in the Zr AES features indicating that the surface is partially oxidized by electron bombardment.

  6. Sputtered neutral Si nC m clusters as a monitor for carbon implantation during C 60 bombardment of silicon

    Science.gov (United States)

    Wucher, A.; Kucher, A.; Winograd, N.; Briner, C. A.; Krantzman, K. D.

    2011-06-01

    The incorporation of carbon atoms into a silicon surface under bombardment with 40-keV C60+ ions is investigated using time-of-flight mass spectrometry of sputtered neutral and ionized Si nC m clusters. The neutral particles emitted from the surface are post-ionized by strong field infrared photoionization using a femtosecond laser system operated at a wavelength of 1400/1700 nm. From the comparison of secondary ion and neutral spectra, it is found that the secondary ion signals do not reflect the true partial sputter yields of the emitted clusters. The measured yield distribution is interpreted in terms of the accumulating carbon surface concentration with increasing C 60 fluence. The experimental results are compared with those from recent molecular dynamics simulations of C 60 bombardment of silicon.

  7. Actinide production from xenon bombardments of curium-248

    Energy Technology Data Exchange (ETDEWEB)

    Welch, R.B.

    1985-01-01

    Production cross sections for many actinide nuclides formed in the reaction of /sup 129/Xe and /sup 132/Xe with /sup 248/Cm at bombarding energies slightly above the coulomb barrier were determined using radiochemical techniques to isolate these products. These results are compared with cross sections from a /sup 136/Xe + /sup 248/Cm reaction at a similar energy. When compared to the reaction with /sup 136/Xe, the maxima in the production cross section distributions from the more neutron deficient projectiles are shifted to smaller mass numbers, and the total cross section increases for the production of elements with atomic numbers greater than that of the target, and decreases for lighter elements. These results can be explained by use of a potential energy surface (PES) which illustrates the effect of the available energy on the transfer of nucleons and describes the evolution of the di-nuclear complex, an essential feature of deep-inelastic reactions (DIR), during the interaction. The other principal reaction mechanism is the quasi-elastic transfer (QE). Analysis of data from a similar set of reactions, /sup 129/Xe, /sup 132/Xe, and /sup 136/Xe with /sup 197/Au, aids in explaining the features of the Xe + Cm product distributions, which are additionally affected by the depletion of actinide product yields due to deexcitation by fission. The PES is shown to be a useful tool to predict the general features of product distributions from heavy ion reactions.

  8. Topographical characterization of Ar-bombarded Si(1 1 1) surfaces by atomic force microscopy

    CERN Document Server

    Niebieskikwiat, D G; Pregliasco, G R; Gayone, J E; Grizzi, O; Sanchez, E A

    2002-01-01

    We used atomic force microscopy to study the topographical changes induced on Si(1 1 1) surfaces by 10-22 keV Ar sup + bombardment. The irradiation was carried on normal to the surface with doses in the 1-60x10 sup 1 sup 6 ions/cm sup 2 range. We observed a first generation of blisters at a critical dose around 3x10 sup 1 sup 6 ions/cm sup 2 , which flakes off at 19x10 sup 1 sup 6 ions/cm sup 2 , and a second generation of smaller blisters between 35 and 45x10 sup 1 sup 6 ions/cm sup 2. Measurements of the mean surface height show that at low irradiation doses the surface inflates because of voids produced by Ar sup + implantation. For doses greater than 20x10 sup 1 sup 6 Ar sup + /cm sup 2 the height decreases linearly because of sputtering, with a slope corresponding to a sputtering yield of 1.4. Finally, we present electron spectra produced during grazing proton bombardment of samples whose topography has been modified by Ar irradiation.

  9. The influence of energetic bombardment on the structure formation of sputtered zinc oxide films. Development of an atomistic growth model and its application to tailor thin film properties

    Energy Technology Data Exchange (ETDEWEB)

    Koehl, Dominik

    2011-02-17

    The focus of this work is the investigation of the growth of zinc oxide (ZnO) thin films. It is demonstrated that with a modified, ion beam assisted sputtering (IBAS) process, zinc oxide films can be deposited which exhibit a markedly improved crystalline order. Furthermore, it is demonstrated that intense energetic oxygen ion bombardment can be utilized to change film texture from the typical (002)-self-texture to an a-axis texture where the (002)-planes are perpendicular to the substrate surface. An understanding of the underlying mechanisms is developed which also facilitates a more detailed understanding of the action of ion bombardment during zinc oxide film growth. It is shown that zinc oxide films are susceptible to the influence of ion bombardment particularly in the nucleation regime of growth and that this finding is generally true for all observed structural changes induced by ion bombardment with various species, energies and flux densities. It is demonstrated not only that the initial growth stage plays an important role in the formation of a preferred growth orientation but also that the action of texture forming mechanisms in subsequent growth stages is comparatively weak. (orig.)

  10. Study and optimisation of SIMS performed with He{sup +} and Ne{sup +} bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Pillatsch, L.; Vanhove, N.; Dowsett, D. [Department “Science and Analysis of Materials” (SAM), Centre de Recherche Public – Gabriel Lippmann, 41 rue du Brill, L-4422 Belvaux (Luxembourg); Sijbrandij, S.; Notte, J. [Carl Zeiss Microscopy LLC, One Corporation Way, Peabody, MA 01960 (United States); Wirtz, T., E-mail: wirtz@lippmann.lu [Department “Science and Analysis of Materials” (SAM), Centre de Recherche Public – Gabriel Lippmann, 41 rue du Brill, L-4422 Belvaux (Luxembourg)

    2013-10-01

    The combination of the high-brightness He{sup +}/Ne{sup +} atomic level ion source with the detection capabilities of secondary ion mass spectrometry (SIMS) opens up the prospect of obtaining chemical information with high lateral resolution and high sensitivity on the Zeiss ORION helium ion microscope (HIM). A feasibility study with He{sup +} and Ne{sup +} ion bombardment is presented in order to determine the performance of SIMS analyses using the HIM. Therefore, the sputtering yields, useful yields and detection limits obtained for metallic (Al, Ni and W) as well as semiconductor samples (Si, Ge, GaAs and InP) were investigated. All the experiments were performed on a Cameca IMS4f SIMS instrument which was equipped with a caesium evaporator and oxygen flooding system. For most of the elements, useful yields in the range of 10{sup −4} to 3 × 10{sup −2} were measured with either O{sub 2} or Cs flooding. SIMS experiments performed directly on the ORION with a prototype secondary ion extraction and detection system lead to results that are consistent with those obtained on the IMS4f. Taking into account the obtained useful yields and the analytical conditions, such as the ion current and typical dwell time on the ORION HIM, detection limits in the at% range and better can be obtained during SIMS imaging at 10 nm lateral resolution with Ne{sup +} bombardment and down to the ppm level when a lateral resolution of 100 nm is chosen. Performing SIMS on the HIM with a good detection limit while maintaining an excellent lateral resolution (<50 nm) is therefore very promising.

  11. Fabrication of nano ion–electron sources and nano-probes by local electron bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Rezeq, Moh’d, E-mail: mohd.rezeq@kustar.ac.ae [Department of Applied Mathematics and Sciences, Khalifa University of Science, Technology and Research (KUSTAR), P.O.B. 127788, Abu Dhabi (United Arab Emirates); Department of Electrical and Computer Engineering, Khalifa University of Science, Technology and Research (KUSTAR), P.O.B. 127788, Abu Dhabi (United Arab Emirates); Ali, Ahmed; Barada, Hassan [Department of Electrical and Computer Engineering, Khalifa University of Science, Technology and Research (KUSTAR), P.O.B. 127788, Abu Dhabi (United Arab Emirates)

    2015-04-01

    Highlights: • A new method for fabricating nanotips with an apex radius around 1 nm is introduced. • This clean process depends only on the physical electron bombardment mechanism. • This method can be applied to any metal or heavily doped semiconductor materials. • The produced single atom nanotips are ideal as sources of electron and ion beams. • These nanotips are advantageous for nano lithography and scanning probe microscopy. - Abstract: A new method for fabricating nano ion–electron sources and nano probes with an apex in the range of 1 nm is introduced. The method is based on bombarding a regular tip apex with electrons extracted and accelerated from a nearby source by the electric field. This can be achieved by placing a metal ring around a precursor metal tip at a level below the tip apex in a field ion microscope (FIM). The metal ring is then heated, by a grounded DC power source, to a temperature below the thermionic emission value. The electric field between the tip and the hot ring is high enough to cause electrons to be extracted from the metal ring, i.e. Schottky field emission, and then accelerated to the shank with energy sufficient to dislodge atoms from the shank. An atomic scale apex with a single atom end can be obtained by monitoring the evolution of the tip apex due to the movement of mobile atoms while adjusting the tip electric field and the temperature of the metal ring. As this method depends only on the electron bombardment mechanism, this makes it a clean process that can be applied to any metal or heavily doped semiconductor materials appropriate for generating a high electric field for FIM applications.

  12. Damage analysis of benzene induced by keV fullerene bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Czerwinski, B. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland)], E-mail: bartlomiej.czerwinski@uj.edu.pl; Rzeznik, L.; Paruch, R. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Garrison, B.J. [Department of Chemistry, Pennsylvania State University, University Park, PA 16802 (United States); Postawa, Z. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland)

    2009-05-01

    Molecular dynamics computer simulations have been used to investigate the damage of a benzene crystal induced by 5 keV C{sub 20}, C{sub 60}, C{sub 120} and C{sub 180} fullerene bombardment. The sputtering yield, the mass distributions, and the depth distributions of ejected organic molecules are analyzed as a function of the size of the projectile. The results indicate that all impinging clusters lead to the creation of almost hemispherical craters, and the process of crater formation only slightly depends on the size of the fullerene projectile. The total sputtering yield as well as the efficiency of molecular fragmentation are the largest for 5 keV C{sub 20}, and decrease with the size of the projectile. Most of the molecules damaged by the projectile impact are ejected into the vacuum during cluster irradiation. Similar behavior does not occur during atomic bombardment where a large portion of fragmented benzene molecules remain inside the crystal after projectile impact. This 'cleaning up' effect may explain why secondary ion mass spectrometry (SIMS) analysis of some organic samples with cluster projectiles can produce significantly less accumulated damage compared to analysis performed with atomic ion beams.

  13. 'Bubble chamber model' of fast atom bombardment induced processes.

    Science.gov (United States)

    Kosevich, Marina V; Shelkovsky, Vadim S; Boryak, Oleg A; Orlov, Vadim V

    2003-01-01

    A hypothesis concerning FAB mechanisms, referred to as a 'bubble chamber FAB model', is proposed. This model can provide an answer to the long-standing question as to how fragile biomolecules and weakly bound clusters can survive under high-energy particle impact on liquids. The basis of this model is a simple estimation of saturated vapour pressure over the surface of liquids, which shows that all liquids ever tested by fast atom bombardment (FAB) and liquid secondary ion mass spectrometry (SIMS) were in the superheated state under the experimental conditions applied. The result of the interaction of the energetic particles with superheated liquids is known to be qualitatively different from that with equilibrium liquids. It consists of initiation of local boiling, i.e., in formation of vapour bubbles along the track of the energetic particle. This phenomenon has been extensively studied in the framework of nuclear physics and provides the basis for construction of the well-known bubble chamber detectors. The possibility of occurrence of similar processes under FAB of superheated liquids substantiates a conceptual model of emission of secondary ions suggested by Vestal in 1983, which assumes formation of bubbles beneath the liquid surface, followed by their bursting accompanied by release of microdroplets and clusters as a necessary intermediate step for the creation of molecular ions. The main distinctive feature of the bubble chamber FAB model, proposed here, is that the bubbles are formed not in the space and time-restricted impact-excited zone, but in the nearby liquid as a 'normal' boiling event, which implies that the temperature both within the bubble and in the droplets emerging on its burst is practically the same as that of the bulk liquid sample. This concept can resolve the paradox of survival of intact biomolecules under FAB, since the part of the sample participating in the liquid-gas transition via the bubble mechanism has an ambient temperature

  14. Thermal effects of impact bombardments on Noachian Mars

    Science.gov (United States)

    Abramov, Oleg; Mojzsis, Stephen J.

    2016-05-01

    Noachian (prior to ca. 3700 Ma) terranes are the oldest and most heavily cratered landscapes on Mars, with crater densities comparable to the ancient highlands of the Moon and Mercury. Intense early cratering affected Mars by melting and fracturing its crust, draping large areas in impact ejecta, generating regional-scale hydrothermal systems, and increasing atmospheric pressure (and thereby, temperature) to periodically re-start an otherwise moribund hydrological cycle. Post primary-accretionary bombardment scenarios that shaped early Mars can be imagined in two ways: either as a simple exponential decay with an approximately 100 Myr half-life, or as a "sawtooth" timeline characterized by both faster-than-exponential decay from primary accretion and relatively lower total delivered mass. Indications are that a late bombardment spike was superposed on an otherwise broadly monotonic decline subsequent to primary accretion, of which two types are investigated: a classical "Late Heavy Bombardment" (LHB) peak of impactors centered at ca. 3900 Ma that lasted 100 Myr, and a protracted bombardment typified by a sudden increase in impactor flux at ca. 4100-4200 Ma with a correspondingly longer decay time (≤400 Myr). Numerical models for each of the four bombardment scenarios cited above show that the martian crust mostly escaped exogenic melting from bombardment. We find that depending on the chosen scenario, other physical effects of impacts were more important than melt generation. Model output shows that between 10 and 100% of the Noachian surface was covered by impact craters and blanketed in resultant (hot) ejecta. If early Mars was generally arid and cold, impact-induced heating punctuated this surface state by intermittently destabilizing the near-subsurface cryosphere to generate regional-scale hydrothermal systems. Rather than being deleterious to the proclivity of Noachian Mars to host an emergent biosphere, this intense early impact environment instead

  15. Actinide production in /sup 136/Xe bombardments of /sup 249/Cf

    Energy Technology Data Exchange (ETDEWEB)

    Gregorich, K.E.

    1985-08-01

    The production cross sections for the actinide products from /sup 136/Xe bombardments of /sup 249/Cf at energies 1.02, 1.09, and 1.16 times the Coulomb barrier were determined. Fractions of the individual actinide elements were chemically separated from recoil catcher foils. The production cross sections of the actinide products were determined by measuring the radiations emitted from the nuclides within the chemical fractions. The chemical separation techniques used in this work are described in detail, and a description of the data analysis procedure is included. The actinide production cross section distributions from these /sup 136/Xe + /sup 249/Cf bombardments are compared with the production cross section distributions from other heavy ion bombardments of actinide targets, with emphasis on the comparison with the /sup 136/Xe + /sup 248/Cm reaction. A technique for modeling the final actinide cross section distributions has been developed and is presented. In this model, the initial (before deexcitation) cross section distribution with respect to the separation energy of a dinuclear complex and with respect to the Z of the target-like fragment is given by an empirical procedure. It is then assumed that the N/Z equilibration in the dinuclear complex occurs by the transfer of neutrons between the two participants in the dinuclear complex. The neutrons and the excitation energy are statistically distributed between the two fragments using a simple Fermi gas level density formalism. The resulting target-like fragment initial cross section distribution with respect to Z, N, and excitation energy is then allowed to deexcite by emission of neutrons in competition with fission. The result is a final cross section distribution with respect to Z and N for the actinide products. 68 refs., 33 figs., 6 tabs.

  16. Desorption of silver atoms from benzene-covered Ag(1 1 1) by energetic Ar{sup +} bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Meserole, C.A. E-mail: cam30@psu.edu; Vandeweert, E.; Postawa, Z.; Dou, Y.; Garrison, B.J.; Winograd, N

    2001-06-01

    Experiments have been conducted to gain insight into the processes of desorption of neutral species from surfaces covered with organic molecules due to bombardment with keV particles. The system is comprised of benzene molecules adsorbed onto Ag(1 1 1) and bombarded with 8 keV Ar{sup +} ions. Molecular dynamics (MD) simulations of the same system have been performed. Results show that the presence of the benzene alters the yield, the kinetic energy distributions, and the angular distributions of the silver atoms. These changes of the desorption characteristics are the result of collisions between the Ag atoms and the benzene molecules adsorbed to the surface. As more benzene is adsorbed to the surface, the changes to the Ag atom desorption characteristics become more pronounced. The simulations reproduce the modifications to the Ag atom energy and angle distributions.

  17. Protons from the alpha-particle bombardment of 23Na

    NARCIS (Netherlands)

    Kuperus, J.

    1964-01-01

    Resonances in the yield of ground-state protons from alpha-particle bombardment of 23Na were investigated in the energy range Eα = 1.0 – 3.3 MeV. At least thirty-eight resonances were observed. Resonance energies and strengths are presented. At nine resonances angular distribution measurements lead

  18. Stable transformation of the oomycete, Phytophthora infestans, using microprojectile bombardment

    DEFF Research Database (Denmark)

    Cvitanich, Cristina; Judelson, Howard S.

    2003-01-01

    Germinated asexual sporangia, zoospores, and mycelia of Phytophthora infestans were transformed to G418-resistance by microprojectile bombardment. After optimization, an average of 14 transformants/shot were obtained, using 10(6) germinated sporangia and gold particles coated with 1 microg...

  19. Ion Implantation of Polymers

    DEFF Research Database (Denmark)

    Popok, Vladimir

    2012-01-01

    are discussed. Related to that, the effects of radiothermolysis, degassing and carbonisation are considered. Specificity of depth distributions of implanted into polymers impurities is analysed and the case of high-fluence implantation is emphasised. Within rather broad topic of ion bombardment, the focus...

  20. Modeling the reduction of gross lithium erosion observed under high-flux deuterium bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Abrams, T., E-mail: tabrams@pppl.gov [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Jaworski, M.A.; Kaita, R.; Nichols, J.H.; Stotler, D.P. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); De Temmerman, G.; Berg, M.A. van den; Meiden, H.J. van der; Morgan, T.W. [FOM Institute DIFFER – Dutch Institute for Fundamental Energy Research, Trilateral Euregio Cluster, Associate EURATOM-FOM, BL-3430 BE Nieuwegein (Netherlands)

    2015-08-15

    Both thin (<1 μm) and thick (∼500 μm) lithium films under high-flux deuterium and neon plasma bombardment were studied in the linear plasma device Magnum-PSI at ion fluxes >10{sup 24} m{sup −2} s{sup −1} and surface temperatures <700 °C. During Ne plasma exposures, Li erosion rates inferred from measurements of Li–I radiation exceed Langmuir Law evaporation, but no previous results exist to benchmark the binary collision approximation (BCA) and thermal sputtering measurements. Measured Li erosion rates during D plasma bombardment were compared to the adatom-evaporation model of thermal sputtering with an additional reduction term to account for the relative D/Li composition of the Li film. This model captures the qualitative evolution of the Li erosion yield but still overestimates the measured erosion by a factor of 5–10. This suggests that additional refinements to the mixed-material model are needed.

  1. Erosion of lithium coatings on TZM molybdenum and graphite during high-flux plasma bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Abrams, T., E-mail: tabrams@pppl.gov [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Jaworski, M.A.; Kaita, R.; Stotler, D.P. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); De Temmerman, G.; Morgan, T.W.; Berg, M.A. van den; Meiden, H.J. van der [FOM Institute DIFFER – Dutch Institute For Fundamental Energy Research, Trilateral Euregio Cluster, Associate EURATOM-FOM, BL-3430 BE Nieuwegein (Netherlands)

    2014-12-15

    Highlights: • A formula for temperature-dependent lithium sputtering and evaporation is proposed. • This formula was tested using the Magnum-PSI linear plasma device. • Lithium-coated TZM molybdenum and graphite samples were exposed to plasmas. • Measured Li erosion rates are significantly lower than the formula predicts. • Evidence of lithium diffusion into graphite substrates was also observed. - Abstract: The rate at which Li films will erode under plasma bombardment in the NSTX-U divertor is currently unknown. It is important to characterize this erosion rate so that the coatings can be replenished before they are completely depleted. An empirical formula for the Li erosion rate as a function of deuterium ion flux, incident ion energy, and Li temperature was developed based on existing theoretical and experimental work. These predictions were tested on the Magnum-PSI linear plasma device capable of ion fluxes >10{sup 24} m{sup −2} s{sup −1}, ion energies of 20 eV and Li temperatures >800 °C. Li-coated graphite and TZM molybdenum samples were exposed to a series of plasma pulses during which neutral Li radiation was measured with a fast camera. The total Li erosion rate was inferred from measurements of Li-I emission. The measured erosion rates are significantly lower than the predictions of the empirical formula. Strong evidence of fast Li diffusion into graphite substrates was also observed.

  2. Jovian Early Bombardment: planetesimal erosion in the inner asteroid belt

    CERN Document Server

    Turrini, Diego; Magni, Gianfranco

    2012-01-01

    The asteroid belt is an open window on the history of the Solar System, as it preserves records of both its formation process and its secular evolution. The progenitors of the present-day asteroids formed in the Solar Nebula almost contemporary to the giant planets. The actual process producing the first generation of asteroids is uncertain, strongly depending on the physical characteristics of the Solar Nebula, and the different scenarios produce very diverse initial size-frequency distributions. In this work we investigate the implications of the formation of Jupiter, plausibly the first giant planet to form, on the evolution of the primordial asteroid belt. The formation of Jupiter triggered a short but intense period of primordial bombardment, previously unaccounted for, which caused an early phase of enhanced collisional evolution in the asteroid belt. Our results indicate that this Jovian Early Bombardment caused the erosion or the disruption of bodies smaller than a threshold size, which strongly depen...

  3. Chiral recognition detected by fast atom bombardment mass spectrometry.

    Science.gov (United States)

    Sawada, M

    1997-01-01

    Detection of chiral recognition in various intermolecular interaction systems using mass spectrometry has become important for the modern fields of analytical chemistry, organic chemistry, and biochemistry due to the characteristic nature of the rapid method and the trace amount needed. This review presents the various methods for detecting and evaluating chiral recognition used primarily in fast atom bombardment mass spectrometry. Emphasis is put on fundamentals and applications of these methods for variously existing enantioselective intermolecular interaction systems.

  4. Transformation of Dendrobium orchid using particle bombardment of protocorms.

    Science.gov (United States)

    Kuehnle, A R; Sugii, N

    1992-08-01

    Transformed dendrobium orchids (Dendrobium x Jaquelyn Thomas hybrids) were recovered from protocorms bombarded by particles coated with the plasmid pGA482GG/cpPRV4, which contains the plant expressible Nos-NPT II and papaya ringspot virus (PRV) coat protein (CP) genes. Approximately 280 protocorms from four crosses were bombarded and potentially transformed tissues were identified by growth and green color on half-strength Murashige and Skoog medium supplemented with 2% sucrose and 50-100 mg 1(-1) kanamycin sulfate. Kanamycin concentrations that prevented growth of nontransformed tissues could not be used for long-term selection because such levels suppressed the regeneration of potentially transformed tissues. PCR and restriction analysis 21 months after treatment found 13 of 13 plants from two crosses, which appeared kanamycin-tolerant, to contain the Nos-NPT II gene, while only one of these plants carried the vector-linked PRV CP-gene. These results support use of particle bombardment for transformation of this important ornamental monocot.

  5. Genetic transformation of Pinus taeda by particle bombardment

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A protocol is presented for genetically engineering loblolly pine (Pinus taeda L.) using particle bombardment. This protocol enabled the routine transformation of loblolly pine plants that were previously difficult to transform. Mature zygotic embryos were used to be bombarded and to generate organogenic callus and transgenic regenerated plants. Plasmid pB48.215 DNA contained a synthetic Bacillus thuringiensis (B.t.) cryIAc coding sequence flanked by the double cauliflower mosaic virus (CaMV) 35S promoter and nopaline synthase (Nos) terminator sequences, and the selectable marker gene, neomycin phosphotransferase II (nptII) controlled by the promoter of the nopaline synthase gene was introduced into loblolly pine tissues by particle bombardment. The transformed tissues were proliferated and selected by kanamycin resistance conferred by the introduced NPTII gene. Shoot regeneration was induced from the kanamycin-resistant callus, and transgenic plantlets were then produced. The presence of the introduced genes in the transgenic loblolly pine plants was confirmed by polymerase chain reactions (PCR) analysis, by Southern blot analysis, and insect feeding assays. The recovered transgenic plants were acclimatized and then established in soil.

  6. The role of impact bombardment history in lunar evolution

    Science.gov (United States)

    Rolf, T.; Zhu, M.-H.; Wünnemann, K.; Werner, S. C.

    2017-04-01

    The lunar surface features diverse impact structures originating from its early bombardment; the largest among them are the lunar basins. Basin-forming impacts delivered large amounts of energy to the target and expelled lots of material that deposited as an insulating blanket in the vicinity of the impact. Here, we investigate how such processes may have altered the lunar evolution. We combine lunar basin chronologies with numerical models of basin formation and 3D thermochemical mantle convection and analyse the role of single generic impacts resulting in basins with varying diameter, formation time, location and ejecta properties. The direct effects of a single impact are enhanced melt generation as well as thermal and heat flux anomalies, but these are limited to ∼ 100 Myr following the impact. We use these insights in multi-impact scenarios more relevant for the Moon, which lead to a widespread ejecta blanket and make impact-induced effects more substantial. Lunar contraction history may be altered by the impact bombardment in favour of an early expansion phase as suggested by recent observations. Moreover, imprints of the early bombardment may be kept in the thermal and compositional state of the Moon's interior until modern times. These can be as large as those induced by uncertainties in bulk lunar heat content, if surface insulation due to ejecta is efficient. In this case, model-predicted present-day thermal profiles match independent constraints better if the bulk Moon is not significantly enriched in refractory elements compared to Earth.

  7. Bacterial spore survival after exposure to HZE particle bombardment -implication for the lithopanspermia hypothesis.

    Science.gov (United States)

    Moeller, Ralf; Berger, Thomas; Matthiä, Daniel; Okayasu, Ryuichi; Kitamura, H.; Reitz, Guenther

    Based on their unique resistance to various space parameters, bacterial spores (mainly spores of Bacillus subtilis) are one of the model systems used for astrobiological studies. More re-cently, spores of B. subtilis have been applied for experimental research on the likelihood of interplanetary transfer of life. Since its first postulation by Arrhenius in 1903, the pansper-mia hypothesis has been revisited many-times, e.g. after the discovery of several lunar and Martian meteorites on Earth [1,2]. These information provided intriguing evidence that rocks may naturally be transferred between the terrestrial planets. The scenario of panspermia, now termed "lithopanspermia" involves three basic hypothetical steps: (i) the escape process, i.e. removal to space of biological material, which has survived being lifted from the surface to high altitudes; (ii) interim state in space, i.e., survival of the biological material over time scales comparable with interplanetary or interstellar passage; (iii) the entry process, i.e. nondestruc-tive deposition of the biological material on another planet [2]. In our research, spores of B. subtilis were used to study the effects of galactic cosmic radiation on spore survival and induced mutations. On an interplanetary journey, outside a protective magnetic field, spore-containing rocks would be exposed to bombardment by high-energy charged particle radiation from galac-tic sources and from the sun. Air-dried spore layers on three different host materials (i.e., non-porous igneous rocks (gabbro), quartz, and spacecraft analog material (aluminum)) were irradiated with accelerated heavy ions (Helium and Iron) with a LET (linear energy transfer) ˆ of 2 and 200 keV/Am, at the Heavy Ion Medical Accelerator (HIMAC) at the National In-stitute of Radiological Sciences, (NIRS), Chiba, Japan in the frame of the HIMAC research project 20B463 "Characterization of heavy ion-induced damage in Bacillus subtilis spores and their global

  8. Studies on Ions and Neutrals Desorbed from Solid Surfaces by Ion and Electron Bombardment

    Science.gov (United States)

    1989-03-24

    Since 1984 Acknowledging AFOSR Support 1. N. Winograd, "Thin Film Electrodes", in Laboratory Techniques in Electroanalytical Chemistry , P. T. Kissinger...Acknowledging AFOSR Support 1. N. Winograd, "Thin Film Electrodes", in Laboratory Techniques in Electroanalytical Chemistry , P. T. Kissinger, Ed., Marcel

  9. Optical, mass, and auger spectra from e-bombarded KBr

    Energy Technology Data Exchange (ETDEWEB)

    Arakawa, E.T.; Kamada, M.

    1988-01-01

    We have measured the mass spectrum and optical emission lines of neutral potassium atoms ejected from KBr at T = 300/degree/K and 443/degree/K bombarded by 2-keV electrons. The room-temperature data may be complicated by the nonstoichiometry of the alkali-enriched sample surface and seem difficult to interpret. The high-temperature sample, which maintains the proper stoichiometry, produces data in support of gas-phase excitation of alkali atoms desorbed from the surface. 15 refs., 4 figs.

  10. a Bombardment Heated Lanthanum-Hexaboride Thermionic Cathode Electron Gun.

    Science.gov (United States)

    Herniter, Marc Efrem

    This dissertation concerns the development and operation of a high current density Pierce-type electron gun with a 0.75-inch-diameter lanthanum hexaboride (LaB _6) thermionic cathode. The objective of this research is to achieve as high a current density as possible from the lanthanum hexaboride cathode. The topics which are addressed are the cathode heating and control system, the Pierce-type electron gun design, and the high voltage pulsing and isolation system. Lanthanum hexaboride is used as a cathode material in applications where high current density and resistance to chemical poisoning are important. Applications include free electron lasers and high power microwave generation. A four stage Marx generator capable of producing 140-kV-peak pulses with a 16 mus decay time constant is used to pulse the electron gun. The cathode is heated to temperatures greater than 1800 ^circ C by electron bombardment from a tungsten filament. Both temperature-limited and space -charge-limited bombardment methods have been investigated. The temperature-limited method is open-loop unstable. Analog and digital control circuits have been developed to control this instability. A simple heating model has been developed and criteria for constructing a controllable system have been established. An instability in the heating system which is caused by evaporation of lanthanum hexaboride from the cathode is discussed. This evaporation reduces the work function of the bombarding filament and makes the temperature -limited bombardment system uncontrollable. The gun has been operated up to voltages of 115 kV achieving beam current densities of 30 A/cm ^2. The electron gun operated dependably up to voltages of 90 kV achieving temperature-limited currents of 50 A. Due to the high fields at the tip of the Pierce -focusing electrode the gun would usually arc at voltages greater than 90 kV. Electron gun operation has been observed in the temperature-limited and space-charge-limited regimes. The

  11. Effect of ion-assisted deposition on optical properties of thin films

    Science.gov (United States)

    Tang, Xuefei; Fan, Zhengxiu

    1990-12-01

    Effects of ion assisted deposition on the propertes of Ti02, Zr02 and 5102 optical coatings were investigated. Substrates were bombarded with different ions--- oxygen ions , argon ions , and the mixture ions of oxygen-argon during deposition. The refractive indices, optical absorptions and laser-induced damage thresholds (LIDT) measurments of these films are reported.

  12. Physico-chemical and mechanical modifications of polyethylene and polypropylene by ion implantation, micro-wave plasma, electron beam radiation and gamma ray irradiation; Modifications physico-chimiques et mecaniques du polyethylene et du polypropylene par implantation ionique, plasma micro-ondes, bombardement d`electrons et irradiation gamma

    Energy Technology Data Exchange (ETDEWEB)

    Liao, J.D.

    1995-03-29

    A polyolefin surface becomes wettable when treated by micro-wave plasma or low-dose nitrogen ion implantation. A short time argon plasma treatment is sufficient to obtain polarizable peroxides on a polyolefin. X-ray photoelectron spectroscopy analyses, paramagnetic electronic resonance analyses, peroxides decomposition, wettability measurements and infrared active spectra analyses have shown that oxidized structures obtained from different treatment techniques play an important role in the interpretation of surface chemical properties of the polymer. Micro-wave plasma treatment, and in particular argon plasma treatment, yields more polarizable groups than ion implantation and is interesting for grafting. Hardness and elasticity modulus, measured by nano-indentation on a polyolefin, increase with an appropriate ion implantation dose. A 1.4 x 10{sup 17} ions.cm{sup -2} dose can multiply by 15 the hardness of high molecular weight polyethylene, and by 7 the elasticity modulus for a 30 nm depth. The viscous-plastic to quasi-elastic transition is shown. The thickness of the modified layer is over 300 nm. The study of friction between a metal sphere and a polyethylene cupula shows that ion implantation in the polymer creates a reticulated hard and elastic layer which improves its mechanical properties and reduces the erosion rate. Surface treatments on polymers used as biomaterials allow to adapt the surface properties to specific applications. 107 refs., 66 figs., 19 tabs., 4 annexes.

  13. Evidence Supporting an Early as Well as Late Heavy Bombardment on the Moon

    Science.gov (United States)

    Frey, Herbert

    2015-01-01

    Evidence supporting an intense early bombardment on the Moon in addition to the traditional Late Heavy Bombardment at approx. 4 BY ago include the distribution of N(50) Crater Retention Ages (CRAs) for candidate basins, a variety of absolute age scenarios for both a "young" and an "old" Nectaris age, and the decreasing contrasts in both topographic relief and Bouguer gravity with increasing CRA.

  14. 33 CFR 334.950 - Pacific Ocean at San Clemente Island, California; Navy shore bombardment areas.

    Science.gov (United States)

    2010-07-01

    ... Island, California; Navy shore bombardment areas. 334.950 Section 334.950 Navigation and Navigable Waters... REGULATIONS § 334.950 Pacific Ocean at San Clemente Island, California; Navy shore bombardment areas. (a) The... degrees true, 5.35 nautical miles; thence 040.4 degrees true to the beach. (3) The waters of the...

  15. Analysis of LED degradation; proton-bombarded GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Hooft, G.W. ' t; Opdorp, C. van (Philips Gloeilampenfabrieken N.V., Eindhoven (Netherlands). Forschungslaboratorium)

    1984-03-01

    An analysis is given of the degradation of light-emitting, Zn-diffused GaAs diodes after proton bombardment. Use is made of a generally applicable method by which the external bulk quantum efficiency and the injection efficiency of an LED can be determined separately. Owing to the increase of non-radiative recombination being larger in the bulk than in the space-charge region, the injection efficiency at constant current first starts to increase and then decreases as a function of irradiation fluence. Furthermore, it is shown that the apparent bulk quantum efficiency decreases superlinearly with the irradiation fluence. This is consistent with the theory for a linear-graded pn junction and the assumption that the concentration of additional killer centres is directly proportional to the irradiation fluence.

  16. Compact electron gun based on secondary emission through ionic bombardment.

    Science.gov (United States)

    Diop, Babacar; Bonnet, Jean; Schmid, Thomas; Mohamed, Ajmal

    2011-01-01

    We present a new compact electron gun based on the secondary emission through ionic bombardment principle. The driving parameters to develop such a gun are to obtain a quite small electron gun for an in-flight instrument performing Electron Beam Fluorescence measurements (EBF) on board of a reentry vehicle in the upper atmosphere. These measurements are useful to characterize the gas flow around the vehicle in terms of gas chemical composition, temperatures and velocity of the flow which usually presents thermo-chemical non-equilibrium. Such an instrument can also be employed to characterize the upper atmosphere if placed on another carrier like a balloon. In ground facilities, it appears as a more practical tool to characterize flows in wind tunnel studies or as an alternative to complex electron guns in industrial processes requiring an electron beam. We describe in this paper the gun which has been developed as well as its different features which have been characterized in the laboratory.

  17. Bombarding Cancer: Biolistic Delivery of therapeutics using Porous Si Carriers

    Science.gov (United States)

    Zilony, Neta; Tzur-Balter, Adi; Segal, Ester; Shefi, Orit

    2013-08-01

    A new paradigm for an effective delivery of therapeutics into cancer cells is presented. Degradable porous silicon carriers, which are tailored to carry and release a model anti-cancer drug, are biolistically bombarded into in-vitro cancerous targets. We demonstrate the ability to launch these highly porous microparticles by a pneumatic capillary gene gun, which is conventionally used to deliver cargos by heavy metal carriers. By optimizing the gun parameters e.g., the accelerating gas pressure, we have successfully delivered the porous carriers, to reach deep targets and to cross a skin barrier in a highly spatial resolution. Our study reveals significant cytotoxicity towards the target human breast carcinoma cells following the delivery of drug-loaded carriers, while administrating empty particles results in no effect on cell viability. The unique combination of biolistics with the temporal control of payload release from porous carriers presents a powerful and non-conventional platform for designing new therapeutic strategies.

  18. Reactive ion beam etching studies of tungsten with CF sub 4 /argon mixtures using ion scattering spectroscopy and SIMS

    Energy Technology Data Exchange (ETDEWEB)

    Cox, T.I.; Deshmukh, V.G.I. (Royal Signals and Radar Establishment, Malvern (UK)); Armour, D.G. (Salford Univ. (UK). Dept. of Electrical Engineering)

    1989-01-01

    Tungsten foil was bombarded at 550 eV with ion beams generated from CF{sub 4}/Ar gas mixtures. The chemical compositions of the bombarded surface and etch products were determined using Ion Scattering Spectroscopy and Secondary Ion Mass Spectrometry respectively. As the ratio CF{sub 4}/Ar was increased, the tungsten surface became covered with fluorine atoms. The products observed were positive ions of W, WF, and WF{sub 2}, with WF{sub 2} being only formed above a threshold concentration of CF{sub 4} in the gas mixture. (author).

  19. Fe embedded in ice: The impacts of sublimation and energetic particle bombardment

    Science.gov (United States)

    Frankland, Victoria L.; Plane, John M. C.

    2015-05-01

    Icy particles containing a variety of Fe compounds are present in the upper atmospheres of planets such as the Earth and Saturn. In order to explore the role of ice sublimation and energetic ion bombardment in releasing Fe species into the gas phase, Fe-dosed ice films were prepared under UHV conditions in the laboratory. Temperature-programmed desorption studies of Fe/H2O films revealed that no Fe atoms or Fe-containing species co-desorbed along with the H2O molecules. This implies that when noctilucent ice cloud particles sublimate in the terrestrial mesosphere, the metallic species embedded in them will coalesce to form residual particles. Sputtering of the Fe-ice films by energetic Ar+ ions was shown to be an efficient mechanism for releasing Fe into the gas phase, with a yield of 0.08 (Ar+ energy=600 eV). Extrapolating with a semi-empirical sputtering model to the conditions of a proton aurora indicates that sputtering by energetic protons (>100 keV) should also be efficient. However, the proton flux in even an intense aurora will be too low for the resulting injection of Fe species into the gas phase to compete with that from meteoric ablation. In contrast, sputtering of the icy particles in the main rings of Saturn by energetic O+ ions may be the source of recently observed Fe+ in the Saturnian magnetosphere. Electron sputtering (9.5 keV) produced no detectable Fe atoms or Fe-containing species. Finally, it was observed that Fe(OH)2 was produced when Fe was dosed onto an ice film at 140 K (but not at 95 K). Electronic structure theory shows that the reaction which forms this hydroxide from adsorbed Fe has a large barrier of about 0.7 eV, from which we conclude that the reaction requires both translationally hot Fe atoms and mobile H2O molecules on the ice surface.

  20. Damage effects of {ion}/{atom} beam milling on MNOS (Al/Si 3N 4/SiO 2/Si) capacitors

    Science.gov (United States)

    Bangert, U.; Belson, J.; Wilson, I. H.

    1984-02-01

    Low energy argon ion and atom beams produced by saddle field sources have been used to study changes in CVD Si 3N 4/SiO 2/Si structures after bombardment of the bare nitride at a particle energy of 2.9 keV. Interface state densities Nst and flatband voltages VFB were extracted from high frequency (1.3 MHz) and quasi-static C- V curves. Bombardment was found to induce an increase in Nst and positive and negative charge storage associated with the nitride (or the nitride/oxide interface). The effect was more pronounced under ion bombardment. On the supposition that displacement damage is similar for ion and atom bombardments the differences in charge storage are interpreted in terms of enhanced trapping under the field associated with ion bombardment.

  1. Ion implantation method for preparing polymers having oxygen erosion resistant surfaces

    Science.gov (United States)

    Lee, Eal H.; Mansur, Louis K.; Heatherly, Jr., Lee

    1995-01-01

    Hard surfaced polymers and the method for making them are generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface, improved wear resistance, and improved oxygen erosion resistance.

  2. Influence of particle bombardment on microstructure and internal stresses of refractory metal suicides on silicon

    Science.gov (United States)

    Hardtke, Ch.; Schilling, W.; Ullmaier, H.

    1991-07-01

    First results on microstructural changes and stress relaxation in thin refractory metal suicide films (TaSi 2 and MoSi 2) caused by particle bombardment are reported. The polycrystalline films had initial tensile stresses of some 10 9 Pa. Exposed to irradiation with Ge ions of 400 keV, both suicides showed a similar stress relaxation behaviour as a function of dose. During room-temperature implantation the initial tensile stress rapidly decreased and turned into compressive stress. Continuous irradiation partly relaxed the compressive stress and resulted in a saturation value of some -10 8 Pa. With increasing implantation temperature, the buildup of compressive stress gradually vanished, leaving only the initial decrease of tensile stress which finally approached zero. Based on microstructural investigations (TEM and X-ray diffraction) it is proposed to explain this behaviour by the combined action of two processes: relaxation of tensile stress by a volume increase due to irradiation-induced amorphization, and Frenkel defect production and relaxation of compressive stress by irradiation-induced densification of amorphous regions and/or Frenkel defect elimination.

  3. Electron-bombarded 〈110〉-oriented tungsten tips for stable tunneling electron emission

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, T. K.; Abe, T.; Nazriq, N. M. K.; Irisawa, T. [Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)

    2016-03-15

    A clean tungsten (W) tip apex with a robust atomic plane is required for producing a stable tunneling electron emission under strong electric fields. Because a tip apex fabricated from a wire by aqueous chemical etching is covered by impurity layers, heating treatment in ultra-high vacuum is experimentally known to be necessary. However, strong heating frequently melts the tip apex and causes unstable electron emissions. We investigated quantitatively the tip apex and found a useful method to prepare a tip with stable tunneling electron emissions by controlling electron-bombardment heating power. Careful characterizations of the tip structures were performed with combinations of using field emission I–V curves, scanning electron microscopy, X-ray diffraction (transmitted Debye-Scherrer and Laue) with micro-parabola capillary, field ion microscopy, and field emission microscopy. Tips were chemically etched from (1) polycrystalline W wires (grain size ∼1000 nm) and (2) long-time heated W wires (grain size larger than 1 mm). Heating by 10-40 W (10 s) was found to be good enough to remove oxide layers and produced stable electron emission; however, around 60 W (10 s) heating was threshold power to increase the tip radius, typically +10 ± 5 nm (onset of melting). Further, the grain size of ∼1000 nm was necessary to obtain a conical shape tip apex.

  4. Efficient and rapid C. elegans transgenesis by bombardment and hygromycin B selection.

    Directory of Open Access Journals (Sweden)

    Inja Radman

    Full Text Available We report a simple, cost-effective, scalable and efficient method for creating transgenic Caenorhabditis elegans that requires minimal hands-on time. The method combines biolistic bombardment with selection for transgenics that bear a hygromycin B resistance gene on agar plates supplemented with hygromycin B, taking advantage of our observation that hygromycin B is sufficient to kill wild-type C. elegans at very low concentrations. Crucially, the method provides substantial improvements in the success of bombardments for isolating transmitting strains, the isolation of multiple independent strains, and the isolation of integrated strains: 100% of bombardments in a large data set yielded transgenics; 10 or more independent strains were isolated from 84% of bombardments, and up to 28 independent strains were isolated from a single bombardment; 82% of bombardments yielded stably transmitting integrated lines with most yielding multiple integrated lines. We anticipate that the selection will be widely adopted for C. elegans transgenesis via bombardment, and that hygromycin B resistance will be adopted as a marker in other approaches for manipulating, introducing or deleting DNA in C. elegans.

  5. On Universality in Sputtering Yields Due to Cluster Bombardment.

    Science.gov (United States)

    Paruch, Robert J; Garrison, Barbara J; Mlynek, Maksymilian; Postawa, Zbigniew

    2014-09-18

    Molecular dynamics simulations, in which atomic and molecular solids are bombarded by Arn (n = 60-2953) clusters, are used to explain the physics that underlie the "universal relation" of the sputtering yield Y per cluster atom versus incident energy E per cluster atom (Y/n vs E/n). We show that a better representation to unify the results is Y/(E/U0) versus (E/U0)/n, where U0 is the sample cohesive energy per atom or molecular equivalent, and the yield Y is given in the units of atoms or molecular equivalents for atomistic and molecular solids, respectively. In addition, we identified a synergistic cluster effect. Specifically, for a given (E/U0)/n value, larger clusters produce larger yields than the yields that are only proportional to the cluster size n or equivalently to the scaled energy E/U0. This synergistic effect can be described in the high (E/U0)/n regime as scaling of Y with (E/U0)(α), where α > 1.

  6. The ballistic performance of the bombard Mons Meg

    Directory of Open Access Journals (Sweden)

    Ian Lewtas

    2016-04-01

    Full Text Available The bombard Mons Meg, located in Edinburgh Castle, with a diameter of 19 inches (48 cm, was one of the largest calibre cannons ever built. Constructed in 1449 and presented to King James II of Scotland in 1454, Mons Meg was used in both military and ceremonial roles in Scotland until its barrel burst in 1680. This paper examines the history, internal, external and terminal ballistics of the cannon and its shot. The likely muzzle velocity was estimated by varying the propellant type and the cannon profile was investigated to identify weak spots in the design that may have led to its failure. Using the muzzle velocity calculated from the internal ballistics, simulations were performed with granite and sandstone shot for varying launch angle and ground temperature. The likely trajectory and range of the cannonballs are described. The internal and external ballistics informed the initial conditions of the terminal ballistic impact scenarios. The performance of the cannonball against both period and modern targets, in the form of a pseudo-castle wall and a monolithic concrete target, respectively, were simulated and are presented and discussed.

  7. The ballistic performance of the bombard Mons Meg

    Institute of Scientific and Technical Information of China (English)

    Ian LEWTAS; Rachael MCALISTER; Adam WALLIS; Clive WOODLEY; Ian CULLIS

    2016-01-01

    The bombard Mons Meg, located in Edinburgh Castle, with a diameter of 19 inches (48 cm), was one of the largest calibre cannons ever built. Constructed in 1449 and presented to King James II of Scotland in 1454, Mons Meg was used in both military and ceremonial roles in Scotland until its barrel burst in 1680. This paper examines the history, internal, external and terminal ballistics of the cannon and its shot. The likely muzzle velocity was estimated by varying the propellant type and the cannon profile was investigated to identify weak spots in the design that may have led to its failure. Using the muzzle velocity calculated from the internal ballistics, simulations were performed with granite and sandstone shot for varying launch angle and ground temperature. The likely trajectory and range of the cannonballs are described. The internal and external ballistics informed the initial conditions of the terminal ballistic impact scenarios. The performance of the cannonball against both period and modern targets, in the form of a pseudo-castle wall and a monolithic concrete target, respectively, were simulated and are presented and discussed.

  8. Did Saturn's rings form during the Late Heavy Bombardment ?

    CERN Document Server

    Charnoz, Sebastien; Dones, Luke H; Salmon, Julien

    2008-01-01

    The origin of Saturn\\' s massive ring system is still unknown. Two popular scenarios - the tidal splitting of passing comets and the collisional destruction of a satellite - rely on a high cometary flux in the past. In the present paper we attempt to quantify the cometary flux during the Late Heavy Bombardment (LHB) to assess the likelihood of both scenarios. Our analysis relies on the so-called Nice model of the origin of the LHB (Tsiganis et al., 2005; Morbidelli et al., 2005; Gomes et al., 2005) and on the size distribution of the primordial trans-Neptunian planetesimals constrained in Charnoz & Morbidelli (2007). We find that the cometary flux on Saturn during the LHB was so high that both scenarios for the formation of Saturn rings are viable in principle. However, a more detailed study shows that the comet tidal disruption scenario implies that all four giant planets should have comparable ring systems whereas the destroyed satellite scenario would work only for Saturn, and perhaps Jupiter. This is ...

  9. Measurement of L-Shell X-ray Production Cross Section of Pb by Fluorine Ion Bombardment%氟离子碰撞引起铅原子L壳层X射线产生截面的实验测量

    Institute of Scientific and Technical Information of China (English)

    吕牛; 常宏伟; 张艳萍; 徐进章; 杜树斌

    2011-01-01

    实验测量了20-50 MeV的F离子碰撞Pb原子产生的L壳层X射线,研究了Pb的L各支壳层X射线产生截面δ(L1),6(Lα), (Lβ),δ(Lγ)和δ(Ltot)与入射离子能量的关系.结果显示:在本能区范围内,Pb原子发射L壳层X射线产生截面随人射离子能量的增加而增加.利用L壳层的辐射跃迁几率、Coster-Kronig跃迁率和L亚壳层的荧光产额将平面波波恩近似(PWBA)和ECPSSR理论计算的电离截面转换为L层X射线产生截面,并与实验结果相比较.结果表明,δ(L1),δ(Lα),δ(Lβ),δ(Lγ)和δ(Ltot)实验测量值与PWBA理论计算值差别很大,ECPSSR理论计算值与δ(L0)实验值符合很好,与δ(L1),δ(Lβ)的实验值差别较小,但与δ(Lγ)的实验值差别较大.%Production cross section of Pb L-shell X-ray induced by 20-50 MeV F5+ ion was measured, and the relationship of X-ray production cross section and impact ion energy was represented.At the same time, inner-shell ionization cross sections given by plane-wave Born approximation (PWBA) theory and the ECPSSR theory were transformed to L-subshell X-ray production cross section by using radiative transition probability, Coster-Kronig transition probability and fluorescence yield.The results were compared with the experimental results.It shows that reasonable agreement between theory and experiment is observed, and the ECPSSR theory is closer to the experiment.

  10. Microanalysis of Ar and He bombarded biomedical polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Manso Silvan, M. [Departamento de Fisica Aplicada C-XII, Universidad Autonoma de Madrid, 28049 Madrid (Spain)]. E-mail: miguel.manso@uam.es; Gago, R. [Departamento de Fisica Aplicada C-XII, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Centro de Microanalisis de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Valsesia, A. [European Commission, Institute for Health and Consumer Protection, Via Enrico Fermi, 21020 Ispra (Italy); Climent Font, A. [Departamento de Fisica Aplicada C-XII, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Centro de Microanalisis de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Duart, J.M. Martinez [Departamento de Fisica Aplicada C-XII, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Rossi, F. [European Commission, Institute for Health and Consumer Protection, Via Enrico Fermi, 21020 Ispra (Italy)

    2007-04-15

    Implantations onto polyethyleneglycol, polycaprolactone and polymethylmethacrylate, carried out with Ar and He ions at 25 and 100 KeV with fluences of 5 x 10{sup 13} cm{sup -2}, have been made with identical ion currents (20 {mu}A) but different sweep areas in order to take into account the effect of the ion flux on the composition and structure of these biopolymers. Vibrational (Fourier transformed infrared spectroscopy), microanalytical (Rutherford backscattering and energy recoil detection) and microscopic techniques (atomic force microscopy) confirm that, even in this low fluence regime, the ion flux effect is responsible of scaled modifications. More interestingly, these techniques indicate that the damage seems to be higher for He. All these factors suggest that He could be preferentially used to engineer biomedical polymers exploiting the tailoring opportunities offered by ion flux effects.

  11. Non-thermodynamic approach to including bombardment-induced post-cascade redistribution of point defects in dynamic Monte Carlo code

    Energy Technology Data Exchange (ETDEWEB)

    Ignatova, V.A. E-mail: velislav@uia.ua.ac.be; Chakarov, I.R.; Katardjiev, I.V

    2003-04-01

    The redistribution of the elements as a result of atomic relocations produced by the ions and the recoils due to the ballistic and transport processes is investigated by making use of a dynamic Monte Carlo code. Phenomena, such as radiation-enhanced diffusion (RED) and bombardment-induced segregation (BIS) triggered by the ion bombardment may also contribute to the migration of atoms within the target. In order to include both RED and BIS in the code, we suggest an approach which is considered as an extension of the binary collision approximation, i.e. it takes place 'simultaneously' with the cascade and acts as a correction to the particle redistribution for low energies. Both RED and BIS models are based on the common approach to treat the transport processes as a result of a random migration of point defects (vacancies and interstitials) according to a probability given by a pre-defined Gaussian. The models are tested and the influence of the diffusion and segregation is illustrated in the cases of 12 keV {sup 121}Sb{sup +} implantation at low fluence in SiO{sub 2}/Si substrate and of self-sputtering of Ga{sup +} ions during profiling of SiO{sub 2}/Si interfaces.

  12. Back bombardment for dispenser and lanthanum hexaboride cathodes

    Directory of Open Access Journals (Sweden)

    Mahmoud Bakr

    2011-06-01

    Full Text Available The back bombardment (BB effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathode’s temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC and lanthanum hexaboride (LaB_{6} thermionic rf gun cathodes. For each, particle simulation codes are used to simulate the BB effect and electron beam dynamics in a thermionic rf gun cathode. A semiempirical equation is also used to investigate the stopping range and deposited heat power of BB electrons in the cathode material. A numerical simulation method is used to calculate the change of the cathode temperature and current density during a single macropulse. This is done by solving two differential equations for the rf gun cavity equivalent circuit and one-dimensional thermal diffusion equation. High electron emission and small beam size are required for generation of a high-brightness electron beam, and so in this work the emission properties of the cathode are taken into account. Simulations of the BB effect show that, for a pulse of 6  μs duration, the DC cathode experiences a large change in the temperature compared with LaB_{6}, and a change in current density 6 times higher. Validation of the simulation results is performed using experimental data for beam current beyond the gun exit. The experimental data is well reproduced using the simulation method.

  13. Generation of ions in a pulsed ion source with an interface based on a polymer track membrane

    Science.gov (United States)

    Balakin, A. A.; Khidirov, S. G.; Buido, E. A.

    2016-10-01

    The time-of-flight spectra of ions generated during the extraction of negative ions from the KI solution in water-glycerin mixture by high-strength electric field pulses are studied using a source with an interface based on a polymer track membrane. It has been shown that the ions formed in secondary processes of bombardment of the membrane surface make a considerable contribution to the observed spectra. It has been found that the peaks of negative hydrogen ions have the highest intensity in the spectrum, indicating effective emission of these ions during the bombardment of polyethylene terephthalate by secondary ions with an energy of about 6 keV. The main trends in the modification of the membrane interface to reduce the fraction of secondary ions in the ion beam have been outlined.

  14. Making junctions between carbon nanotubes using an ion beam

    CERN Document Server

    Krasheninnikov, A V; Keinonen, J; Banhart, F

    2003-01-01

    Making use of empirical potential molecular dynamics, we study ion bombardment of crossed single-walled carbon nanotubes as a tool to join the nanotubes. We demonstrate that ion irradiation should result in welding of crossed nanotubes, both suspended and deposited on substrates. We further predict optimum ion doses and energies for ion-mediated nanotube welding which may potentially be used for developing complicated networks of joined nanotubes.

  15. The influence of projectile ion induced chemistry on surface pattern formation

    Science.gov (United States)

    Karmakar, Prasanta; Satpati, Biswarup

    2016-07-01

    We report the critical role of projectile induced chemical inhomogeneity on surface nanostructure formation. Experimental inconsistency is common for low energy ion beam induced nanostructure formation in the presence of uncontrolled and complex contamination. To explore the precise role of contamination on such structure formation during low energy ion bombardment, a simple and clean experimental study is performed by selecting mono-element semiconductors as the target and chemically inert or reactive ion beams as the projectile as well as the source of controlled contamination. It is shown by Atomic Force Microscopy, Cross-sectional Transmission Electron Microscopy, and Electron Energy Loss Spectroscopy measurements that bombardment of nitrogen-like reactive ions on Silicon and Germanium surfaces forms a chemical compound at impact zones. Continuous bombardment of the same ions generates surface instability due to unequal sputtering and non-uniform re-arrangement of the elemental atom and compound. This instability leads to ripple formation during ion bombardment. For Argon-like chemically inert ion bombardment, the chemical inhomogeneity induced boost is absent; as a result, no ripples are observed in the same ion energy and fluence.

  16. Erosion Processes of Carbon Materials under Hydrogen Bombardment and their Mitigation by Doping

    Energy Technology Data Exchange (ETDEWEB)

    Juan Pardo, E. de; Balden, M.B.; Cieciwa, B.; Roth, J. [Max-Planck-Inst. fuer Plasmaphysik, Garching (Germany); Garcia-Rosales, C. [Univ. de Navarra, San Sebastian (Spain). Campus Tecnologico

    2004-08-01

    Two regimes of the chemical erosion of carbon materials under hydrogen bombardment have been separated: (i) the thermally activated regime, Y{sub therm}; with the maximal erosion yield in the temperature range between 550 and 850 K, and (ii) the so-called 'surface' regime, Y{sub surf} ; at low temperatures ({approx} 300K) and low impact energies (< 100 eV). Doping carbon materials largely reduces their chemical reactivity with hydrogen and their chemical erosion. In addition, dopant enrichment at the surface due to preferential sputtering of carbon contributes to a reduction of the erosion yield. Erosion measurements with 30 eV and 1 keV D for various doped carbon materials with dopant concentration between 0.25 and 13 at.% were performed at temperatures between 77 and 1100 K. For Y{sub surf} at high ion fluences (>10{sup 25} D/m{sup 2}); a reduction of the erosion yield by one order of magnitude is observed for fine-grain carbide-doped graphites. Scanning electron microscopy (SEM) allows to associate these fluence dependencies with the evolution of a rough surface morphology of several mm in the erosion area. For Y{sub therm} an almost complete suppression of the CD{sub 4}-production yield is observed for Tidoped C layers. This reduction due to the doping on atomic scale exceeds all previously observed reductions of materials with a coarser dopant distribution. For all investigated carbon materials, the yield below RT does not depend on temperature.

  17. Ion-beam-assisted hexagonal diamond formation from C sub 6 sub 0 fullerene

    CERN Document Server

    Zhu, X D; Naramoto, H; Narumi, K; Miyashita, A; Miyashita, K

    2003-01-01

    Ions are commonly believed to be detrimental to diamond growth because of the high degree of lattice disorder induced by ion bombardments. In this paper, we examine the possibility of preparing diamond using thermally evaporated C sub 6 sub 0 and simultaneous bombardment with Ne sup + ions. It is found that the diamonds can be grown on Si wafers in the appropriate substrate temperature and ion energy ranges. Micro-Raman spectroscopy, x-ray diffractometry, and scanning electronic microscopy were employed to characterize the deposited specimen. These measurements provide definite evidence of the structure of nanosized hexagonal diamond. The mechanism responsible for the diamond formation is discussed.

  18. Studies of Improving the Frequency of Indica Rice Transformation by Biolistic Bombardment

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In order to improve the frequency of indica rice transformation by biolistic bombardment, suitable culture conditions for embryonic calli,an optimal selection scheme for resistant calli and seedlings, and optimum bombardment parameters a investigated by using 14 commercially important indica rice cultivars. The main results show that the CC medium with 36g/L mannitol is a scheme subculture medium in which the browning of indica rice calli can be mitigated significantly; The concentration of 30~40mg/L Hyg or 150~200mg/L G418 or 10~20 mg/L Basta is suitable for selection of resistant calli; The transformation parameters of 100μg gold powder absorbing 0.2μg DNA per shot and 900 psi helium pressure and 6 cm bombardment distance and bombarded twice for each plate give the best result; Keeping the target calli on osmotic medium containing 60g/L mannitol from 12 ~24h before bombardment to 24~48h after it can increase the efficiencies of transformation . Furthermore, some transgenic indica rice plants are obtained using this optimized transformation system.

  19. Non-thermodynamic approach to including bombardment-induced post-cascade redistribution of point defects in dynamic Monte Carlo code

    CERN Document Server

    Ignatova, V A; Katardjiev, I V

    2003-01-01

    The redistribution of the elements as a result of atomic relocations produced by the ions and the recoils due to the ballistic and transport processes is investigated by making use of a dynamic Monte Carlo code. Phenomena, such as radiation-enhanced diffusion (RED) and bombardment-induced segregation (BIS) triggered by the ion bombardment may also contribute to the migration of atoms within the target. In order to include both RED and BIS in the code, we suggest an approach which is considered as an extension of the binary collision approximation, i.e. it takes place 'simultaneously' with the cascade and acts as a correction to the particle redistribution for low energies. Both RED and BIS models are based on the common approach to treat the transport processes as a result of a random migration of point defects (vacancies and interstitials) according to a probability given by a pre-defined Gaussian. The models are tested and the influence of the diffusion and segregation is illustrated in the cases of 12 keV ...

  20. ANALYTICAL MODELING OF ELECTRON BACK-BOMBARDMENT INDUCED CURRENT INCREASE IN UN-GATED THERMIONIC CATHODE RF GUNS

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Sun, Y. [Argonne; Harris, J. R. [AFRL, NM; Lewellen, J. W. [Los Alamos Natl. Lab.

    2016-09-28

    In this paper we derive analytical expressions for the output current of an un-gated thermionic cathode RF gun in the presence of back-bombardment heating. We provide a brief overview of back-bombardment theory and discuss comparisons between the analytical back-bombardment predictions and simulation models. We then derive an expression for the output current as a function of the RF repetition rate and discuss relationships between back-bombardment, fieldenhancement, and output current. We discuss in detail the relevant approximations and then provide predictions about how the output current should vary as a function of repetition rate for some given system configurations.

  1. Modification of graphene by ion beam

    Science.gov (United States)

    Gawlik, G.; Ciepielewski, P.; Jagielski, J.; Baranowski, J.

    2017-09-01

    Ion induced defect generation in graphene was analyzed using Raman spectroscopy. A single layer graphene membrane produced by chemical vapor deposition (CVD) on copper foil and then transferred on glass substrate was subjected to helium, carbon, nitrogen, argon and krypton ions bombardment at energies from the range 25 keV to 100 keV. A density of ion induced defects and theirs mean size were estimated by using Raman measurements. Increasing number of defects generated by ion with increase of ion mass and decrease of ion energy was observed. Dependence of ion defect efficiency (defects/ion) on ion mass end energy was proportional to nuclear stopping power simulated by SRIM. No correlation between ion defect efficiency and electronic stopping power was observed.

  2. In situ observation of surface morphology evolution in tungsten under focused Ga{sup +} ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ran Guang, E-mail: gran@umich.edu [School of Energy Research, Xiamen University, Xiamen, Fujian 361005 (China); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Liu Xiang; Wu Jihong [Southwestern Institute of Physics, Chengdu, Sichuan 610041 (China); Li Ning [School of Energy Research, Xiamen University, Xiamen, Fujian 361005 (China); Zu Xiaotao [Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Wang Lumin, E-mail: lmwang@umich.edu [School of Energy Research, Xiamen University, Xiamen, Fujian 361005 (China); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2012-05-15

    The effects of energetic Ga ion bombardment on the surface morphology of mechanically polished polycrystalline tungsten are investigated by focused Ga{sup +} ion beam irradiation with in situ scanning electron microscopy, as well as ex situ atomic force microscopy. The amount of removed material from the tungsten surface increased with increasing of incident ion angle, and also increased with ion energy from 5 to 30 keV while keeping all other bombardment parameters constant. The nanoneedle-shaped morphology formed by self-assembly in the surface of tungsten under off-normal angle bombardment, the larger the incident angle, the easier for the needle formation. In contrast, only a net-like microstructure formed under normal incident angle. Moreover, more Ga{sup +} ion fluence was needed to form pores at normal incident angle comparing to that under 52 Degree-Sign incident angle.

  3. Heavy-Ion-Induced Electronic Desorption of Gas from Metals

    CERN Document Server

    Molvik, A W; Mahner, E; Kireeff Covo, M; Bellachioma, M C; Bender, M; Bieniosek, F M; Hedlund, E; Krämer, A; Kwan, J; Malyshev, O B; Prost, L; Seidl, P A; Westenskow, G; Westerberg, L

    2007-01-01

    During heavy-ion operation in several particle accelerators worldwide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion-induced gas desorption scales with the electronic energy loss (dEe/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.

  4. Heavy-ion induced electronic desorption of gas from metals

    Energy Technology Data Exchange (ETDEWEB)

    Molvik, A W; Kollmus, H; Mahner, E; Covo, M K; Bellachioma, M C; Bender, M; Bieniosek, F M; Hedlund, E; Kramer, A; Kwan, J; Malyshev, O B; Prost, L; Seidl, P A; Westenskow, G; Westerberg, L

    2006-12-19

    During heavy ion operation in several particle accelerators world-wide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion induced gas desorption scales with the electronic energy loss (dE{sub e}/d/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.

  5. Energy Reflected from Solid Targets Bombarded keV Protons and Helium Ions

    DEFF Research Database (Denmark)

    Andersen, Hans Henrik; Lenskjaer, T.; Sidenius, G.

    1976-01-01

    The energy‐reflection coefficient γ has been measured for keV protons impinging on Cu, Au, and Pb and helium impinging on Si, Ag, Ta, and Pb. The results are obtained by entirely independent techniques in three different laboratories. They agree within the stated accuracies of 10%. For a given...

  6. Structural and quantitative aspects of radical formation after heavy ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Dusemund, B.; Hoffmann, A.K.; Weiland, B.; Huettermann, J. [Klinikum Homburg (Germany). Fachrichtung Biophysik

    1997-09-01

    In this report the authors present a summary of their recent attempts aiming at clarifying some basic structural and quantitative aspects of free radical formation in DNA constituents and in DNA as well as of product analysis from nucleotide model compounds. (orig./MG)

  7. Surface channelling in grazing-incidence ion bombardment of a stepped surface

    Energy Technology Data Exchange (ETDEWEB)

    Rosandi, Yudi [Fachbereich Physik, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany); Urbassek, Herbert M. [Fachbereich Physik, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany)]. E-mail: urbassek@rhrk.uni-kl.de

    2007-03-15

    Using molecular-dynamics simulation, the impact of a 5keV Ar atom at 83 deg. incidence angle towards the surface normal onto a stepped Pt(111) surface is investigated. The projectile impinges with a [11-bar2] azimuth on a B step. The channelling of trajectories below the upper terrace is characterized in terms of the distribution of channelling lengths and the energy loss of channelled projectiles. The influence of target temperature is studied by simulating targets at 0K and at 550K.

  8. Transmission secondary ion mass spectrometry using 5 MeV C60+ ions

    Science.gov (United States)

    Nakajima, K.; Nagano, K.; Suzuki, M.; Narumi, K.; Saitoh, Y.; Hirata, K.; Kimura, K.

    2014-03-01

    In the secondary ion mass spectrometry (SIMS), use of cluster ions has an advantage of producing a high sensitivity of intact large molecular ions over monatomic ions. This paper presents further yield enhancement of the intact biomolecular ions by measuring the secondary ions emitted in the forward direction. Phenylalanine amino acid films deposited on self-supporting thin Si3N4 films were bombarded with 5 MeV C60 ions. Secondary ions emitted in the forward and backward directions were measured. The yield of intact phenylalanine molecular ions emitted in the forward direction is significantly enhanced compared to the backward direction while fragment ions are suppressed. This suggests a large potential of using transmission cluster ion SIMS for the analysis of biological materials.

  9. Transient gene expression of b-glucuronidase in citrus thin epicotyl transversal sections using particle bombardment

    Directory of Open Access Journals (Sweden)

    Bespalhok Filho João C.

    2003-01-01

    Full Text Available Studies were carried out to optimize the conditions for transient gene expression through particle bombardment on Carrizo citrange (Citrus sinensis x Poncirus trifoliata thin epicotyl sections. The best conditions for transient GUS expression were: M-25 tungsten particles, 1550 psi helium pressure, 9 cm distance between specimen and DNA/particle holder and culture of explants in a high osmolarity medium (0.2 M mannitol + 0.2 M sorbitol 4 h prior and 20 h after bombardment. Under these conditions, an average of 102 blue spots per bombardment (20 explants/plate were achieved. This protocol is currently being used for transformation of Carrizo citrange and sweet orange (Citrus sinensis.

  10. Transgene organisation in potato after particle bombardment-mediated (co-) transformation using plasmids and gene cassettes

    NARCIS (Netherlands)

    Romano, A.; Raemakers, C.J.J.M.; Bernardi, J.; Visser, R.G.F.; Mooibroek, A.

    2003-01-01

    Protocols for efficient co-transformation of potato internodes with genes contained in separate plasmids or gene cassettes (i.e., linear PCR fragments comprising a promoter-gene-terminator) using particle bombardment were established. Twenty-eight out of 62 (45%) and 11 out of 65 (17%) plants transf

  11. Particle bombardment and the genetic enhancement of crops: myths and realities

    NARCIS (Netherlands)

    Altpeter, F.; Baisakh, N.; Beachy, R.; Bock, R.; Capell, T.; Christou, P.; Daniell, H.; Datta, K.; Datta, S.; Dix, P.J.; Fauquet, C.; Huang, N.; Kohli, A.; Mooibroek, H.; Nicholson, L.; Nguyen, T.T.; Nugent, G.; Raemakers, C.J.J.M.; Romano, A.; Somers, D.A.; Stoger, E.; Taylor, N.; Visser, R.G.F.

    2005-01-01

    DNA transfer by particle bombardment makes use of physical processes to achieve the transformation of crop plants. There is no dependence on bacteria, so the limitations inherent in organisms such as Agrobacterium tumefaciens do not apply. The absence of biological constraints, at least until DNA ha

  12. Orienterende Fast Atom Bombardment (FAB) experimenten met de VG-70-SQ massaspectrometer

    NARCIS (Netherlands)

    Hove GJ ten; Boer AC den; Burgers PC; Jong APJM de

    1988-01-01

    Eerste orienterende metingen met fast atom bombardment (FAB) ionisatietechniek zijn uitgevoerd. De techniek werd toegepast bij de analyse van korte-keten polypeptiden (n=2-5), cyclosporine, NADP en microperoxidase. Onderzocht werd de invloed van de aard van de matrix (glycerol, thioglycerol) op

  13. Erosion of lithium coatings on TZM molybdenum and graphite during high-flux plasma bombardment

    NARCIS (Netherlands)

    Abrams, T.; Jaworski, M. A.; Kaita, R.; Stotler, D. P.; De Temmerman, G.; Morgan, T. W.; van den Berg, M. A.; van der Meiden, H. J.

    2014-01-01

    Abstract The rate at which Li films will erode under plasma bombardment in the NSTX-U divertor is currently unknown. It is important to characterize this erosion rate so that the coatings can be replenished before they are completely depleted. An empirical formula for the Li erosion rate as a

  14. Theoretical simulations of atomic and polyatomic bombardment of an organic overlayer on a metallic substrate

    CERN Document Server

    Krantzman, K D; Delcorte, A; Garrison, B J

    2003-01-01

    Our previous molecular dynamics simulations on initial test systems have laid the foundation for understanding some of the effects of polyatomic bombardment. In this paper, we describe simulations of the bombardment of a more realistic model system, an overlayer of sec-butyl-terminated polystyrene tetramers on a Ag left brace 1 1 1 right brace substrate. We have used this model system to study the bombardment with Xe and SF sub 5 projectiles at kinetic energies ranging from 0.50 to 5.0 keV. SF sub 5 sputters more molecules than Xe, but a higher percentage of these are damaged rather than ejected intact when the bombarding energy is greater than 0.50 keV. Therefore, at energies comparable to experimental values, the efficiency, measured as the yield-to-damage ratio, is greater with Xe than SF sub 5. Stable and intact molecules are generally produced by upward moving substrate atoms, while fragments are produced by the upward and lateral motion of reflected projectile atoms and fragments from the target molecul...

  15. Particle Bombardment of Ex Vivo Skin to Deliver DNA and Express Proteins

    NARCIS (Netherlands)

    Sokol, Ena; Nijenhuis, Miranda; Sjollema, Klaas A; Jonkman, Marcel F; Pas, Hendri H; Giepmans, Ben N G

    2017-01-01

    Particle bombardment of gold microparticles coated with plasmids, which are accelerated to high velocity, is used for transfection of cells within tissue. Using this method, cDNA encoding proteins of interest introduced into ex vivo living human skin enables studying of proteins of interest in real

  16. Modified morphology of graphene sheets by Argon-atom bombardment: molecular dynamics simulations.

    Science.gov (United States)

    Wei, Xiao-Lin; Zhang, Kai-Wang; Wang, Ru-Zhi; Liu, Wen-Liang; Zhong, Jian-Xin

    2011-12-01

    By a molecular dynamics method, we simulated the process of Argon-atom bombardment on a graphene sheet with 2720 carbon atoms. The results show that, the damage of the bombardment on the graphene sheet depends not only on the incident energy but also on the particle flux density of Argon atoms. To compare and analyze the effect of the incident energy and the particle flux density in the Argon-atom bombardment, we defined the impact factor on graphene sheet by calculating the broken-hole area. The results indicate that, there is an exponential accumulated-damage for the impact of both the incident energy and the particle flux density and there is a critical incident energy ranging from 20-30 eV/atom in Argon-atom bombardment. Different configurations, such as sieve-like and circle-like graphene can be formed by controlling of different particle flux density as the incident energy is more than the critical value. Our results supply a feasible method on fabrication of porous graphene-based materials for gas-storages and molecular sieves, and it also helps to understand the damage mechanism of graphene-based electronic devices under high particle radiation.

  17. Use of the Ion-Plasma Treatment for Improving the Structural Strength of Items

    Directory of Open Access Journals (Sweden)

    I.S. Tatarkina

    2012-03-01

    Full Text Available The paper shows that the ion bombardment (IB by low-energy ions essentially influences the behavior of a specimen under tension testing changing strength and ductility of the item as a whole though the same properties of metal remain in its core. IB also increases fatigue strength and can be used for improving the ductility of sheet steels. This treatment is especially effective for items with technological stress concentrators and is recommended as a very effective and simple method of improving their structural strength. The phenomenon is explained by surface nanostructuring during ion bombardment.

  18. Using polyatomic primary ions to probe an amino acid and a nucleic base in water ice

    Energy Technology Data Exchange (ETDEWEB)

    Conlan, X.A. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: x.conlan@postgrad.manchester.ac.uk; Biddulph, G.X. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: G.Biddulph@postgrad.manchester.ac.uk; Lockyer, N.P. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom); Vickerman, J.C. [Surface Analysis Research Centre, School of Chemical Engineering and Analytical Science, University of Manchester, P.O. Box 88, Manchester M60 1QD (United Kingdom)]. E-mail: John.Vickerman@manchester.ac.uk

    2006-07-30

    In this study on pure water ice, we show that protonated water species [H{sub 2}O] {sub n}H{sup +} are more prevalent than (H{sub 2}O) {sub n} {sup +} ions after bombardment by Au{sup +} monoatomic and Au{sub 3} {sup +} and C{sub 60} {sup +} polyatomic projectiles. This data also reveals significant differences in water cluster yields under bombardment by these three projectiles. The amino acid alanine and the nucleic base adenine in solution have been studied and have been shown to have an effect on the water cluster ion yields observed using an Au{sub 3} {sup +} ion beam.

  19. Secondary Ion Mass Spectrometry Imaging of Dictyostelium discoideum Aggregation Streams

    Energy Technology Data Exchange (ETDEWEB)

    Debord, J. Daniel; Smith, Donald F.; Anderton, Christopher R.; Heeren, Ronald M.; Pasa-Tolic, Ljiljana; Gomer, Richard H.; Fernandez-Lima, Francisco A.

    2014-06-09

    High resolution imaging mass spectrometry could become a valuable tool for cell and developmental biology, but both, high spatial and mass spectral resolution are needed to enable this. In this report, we employed Bi3 bombardment time-of-flight (Bi3 ToF-SIMS) and C60 bombardment Fourier transform ion cyclotron resonance secondary ion mass spectrometry (C60 FTICR-SIMS) to image Dictyostelium discoideum aggregation streams. Nearly 300 lipid species were identified from the aggregation streams. High resolution mass spectrometry imaging (FTICR-SIMS) enabled the generation of multiple molecular ion maps at the nominal mass level and provided good coverage for fatty acyls, prenol lipids, and sterol lipids. The comparison of Bi3 ToF-SIMS and C60 FTICR-SIMS suggested that while the first provides fast, high spatial resolution molecular ion images, the chemical complexity of biological samples warrants the use of high resolution analyzers for accurate ion identification.

  20. Evaporation of ion-irradiated disks

    CERN Document Server

    Dullemond, C P

    2005-01-01

    We calculate the evaporation of a cool accretion disk around a black hole due to the ion-bombardment by an ion supported accretion flow (here ISAF, or optically thin ADAF). As first suggested by Spruit & Deufel (2002), this evaporation takes place in two stages: ion bombardment of the cool disk (Shakura-Sunyaev disk: SSD) produces an intermediate-temperature layer on top of the disk (`warm layer') which constitutes an independent accretion flow on both sides of the SSD. As this warm material accretes inward of the inner radius of the SSD, it becomes thermally unstable by lack of cooling of photons, and evaporates into the ISAF, thereby feeding the latter. Angular momentum conservation forces a certain fraction of the ISAF material to move outward, where it can bombard the SSD with its hot ions. The flow geometry is derived by computing stationary solutions of the continuity- and angular momentum equations for the three components (ISAF, warm flow and SSD). The overall radiative output is dominated by hard...

  1. Sputtering of solid nitrogen by keV helium ions

    DEFF Research Database (Denmark)

    Ellegaard, O.; Schou, Jørgen; Sørensen, H.;

    1993-01-01

    Solid nitrogen has become a standard material among the frozen molecular gases for electronic sputtering. We have combined measurements of sputtering yields and energy spectra from nitrogen bombarded by 4-10 keV helium ions. The data show that the erosion is electronic rather than knockon...

  2. Nanoscale patterns produced by self-sputtering of solid surfaces: The effect of ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, R. Mark [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States); Hofsäss, Hans [II. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen (Germany)

    2016-08-21

    A theory of the effect that ion implantation has on the patterns produced by ion bombardment of solid surfaces is introduced. For simplicity, the case of self-sputtering of an elemental material is studied. We find that implantation of self-ions has a destabilizing effect along the projected beam direction for angles of incidence θ that exceed a critical value. In the transverse direction, ion implantation has a stabilizing influence for all θ.

  3. Erosion of Be and deposition of C and O due to bombardment with C{sup +} and CO{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Eckstein, W.; Goldstrass, P.; Linsmeier, Ch. [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

    1998-01-01

    The bombardment of Be with 3 and 5 keV C{sup +} and CO{sup +} at normal incidence is investigated experimentally and by computer simulation with the program TRIDYN. The deposited amount of C and O is determined experimentally and found in good agreement with calculated data for C bombardment. Chemical erosion dominates at higher fluences for CO{sup +} bombardment. Calculations are then used to determine the sputter yield of Be at steady state conditions as a function of the plasma edge electron temperature for two C impurity concentrations in the incident D flux, typical for fusion plasmas. The fluence to reach steady state conditions is also investigated. (author)

  4. Transfer of Bt-toxin protein gene into maize by high-velocity microprojectile bombardments and regeneration of transgenic plants

    Institute of Scientific and Technical Information of China (English)

    王国英; 杜天兵; 张宏; 谢友菊; 戴景瑞; 米景九; 李太源; 田颖川; 乔利亚; 莽克强

    1995-01-01

    Bt-toxin protein gene was successfully transferred into maize by the microprojectile bombard-ments of cell suspension,embryogenic calli and immature embryos with a Chinese-made particle gun(JQ-700).Although the bombarded embryogenic calli and immature embryos produced less mean transformants per dishthan the cell suspensions,they were the suitable materials for maize transformation because their culture andregeneration have been achieved in most maize cultivars.The evaluation on the resistance of transgenic plantsto corn borer shows the significant difference between them,from highly resistant to susceptible.

  5. Ion source design for industrial applications

    Science.gov (United States)

    Kaufman, H. R.; Robinson, R. S.

    1981-01-01

    The more frequently used design techniques for the components of broad-beam electron bombardment ion sources are discussed. The approach used emphasizes refractory metal cathodes and permanent-magnet multipole discharge chambers. Design procedures and sample calculations are given for the discharge chamber, ion optics, the cathodes, and the magnetic circuit. Hardware designs are included for the isolator, cathode supports, anode supports, pole-piece assembly, and ion-optics supports. A comparison is made between two-grid and three-grid optics. The designs presented are representative of current technology and are adaptable to a wide range of configurations.

  6. Ion source design for industrial applications

    Science.gov (United States)

    Kaufman, H. R.; Robinson, R. S.

    1981-01-01

    The more frequently used design techniques for the components of broad-beam electron bombardment ion sources are discussed. The approach used emphasizes refractory metal cathodes and permanent-magnet multipole discharge chambers. Design procedures and sample calculations are given for the discharge chamber, ion optics, the cathodes, and the magnetic circuit. Hardware designs are included for the isolator, cathode supports, anode supports, pole-piece assembly, and ion-optics supports. A comparison is made between two-grid and three-grid optics. The designs presented are representative of current technology and are adaptable to a wide range of configurations.

  7. Erosion yield of metal surface under ion pulsed irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Krivobokov, Valery; Stepanova, Olga, E-mail: omsa@tpu.ru; Yuryeva, Alena

    2013-11-15

    The paper is devoted to the study of erosion processes on a metal surface (Ag, Ni, Cu, W) under argon ion bombardment. The erosion yields including the sputtered and evaporated particles have been calculated for a wide range of the initial ion energy (1–1000 keV). They are revealed to reach the values from units to 10{sup 4} atom/ion under a pulsed ion beam with the power density of 10{sup 2}–10{sup 10} W/cm{sup 2}. The ion beam and target parameters are shown to influence on the erosion intensity.

  8. Impact-driven ice loss in outer Solar System satellites: Consequences for the Late Heavy Bombardment

    Science.gov (United States)

    Nimmo, F.; Korycansky, D. G.

    2012-05-01

    We use recent hydrodynamical results (Kraus, R.G., Senft, L.G., Stewart, S.S. [2011]. Icarus, 214, 724-738) for the production of water vapor by hypervelocity impacts on ice targets to assess which present-day major satellites of Jupiter, Saturn, and Uranus would have lost mass due to impact vaporization during an era of massive bombardment similar to the Late Heavy Bombardment in the inner Solar System. Using impactor populations suggested by recent work (Charnoz, S., Morbidelli, A., Dones, L., Salmon, J. [2009]. Icarus, 199, 413-428; Barr, A.C., Canup, R.M. [2010]. Nat. Geosci., 3, 164-167), we find that several satellites would have lost all their HO; we suggest that the most likely resolution of this paradox is that either the LHB delivered ≈10 times less mass to the outer Solar System than predicted by the standard Nice Model, or that the inner satellites formed after the LHB.

  9. Disruption and reaccretion of midsized moons during an outer solar system Late Heavy Bombardment

    Science.gov (United States)

    Movshovitz, N.; Nimmo, F.; Korycansky, D. G.; Asphaug, E.; Owen, J. M.

    2015-01-01

    We investigate the problem of satellite survival during a hypothetical Late Heavy Bombardment in the outer solar system, as predicted by the Nice model (Tsiganis, Gomes, Morbidelli, and Levison 2005, Nature 435). Using a Monte Carlo approach we calculate, for satellites of Jupiter, Saturn, and Uranus, the probability of experiencing a catastrophic collision during the Late Heavy Bombardment (LHB). We find that Mimas, Enceladus, Tethys, and Miranda experience at least one catastrophic impact in every simulation. Because reaccretion is expected to be rapid, these bodies will have emerged as scrambled mixtures of rock and ice. Tidal heating may have subsequently modified the latter three, but in the nominal LHB model Mimas should be a largely undifferentiated, homogeneous body. A differentiated Mimas would imply either that this body formed late or that the Nice model requires significant modification.

  10. Mass spectrometric identification of C60 fragmentation regimes under energetic Cs+ bombardment

    CERN Document Server

    Zeeshan, Sumaira; Ahmad, Shoaib

    2016-01-01

    Three C60 fragmentation regimes in fullerite bombarded by Cs+ are identified as a function of its energy. C2 is the major species sputtered at all energies. For E(Cs+) < 1 keV C2 emissions dominate. C2 and C1 have highest intensities between 1 and 3 keV with increasing contributions from C3 and C4. Intensities of all fragments maximize around 2 keV. Above 3 keV, fragments densities stabilize. The roles of and the contributions from direct recoils and collision cascades are determined. Maximum direct recoil energy delivered to the C60 fullerite cage is 210 eV at which only C2 emissions occur is identified and an explanation provided. The three fragmentation regimes under continued Cs+ bombardment eventually lead to complete destruction of the C60 cages transforming fullerite into amorphous carbon

  11. Combined molecular dynamics and analytical model for repetitive cluster bombardment of solids

    Energy Technology Data Exchange (ETDEWEB)

    Garrison, Barbara J., E-mail: bjg@psu.edu [Department of Chemistry, 104 Chemistry Building, Penn State University, University Park, PA 16802 (United States); Paruch, Robert J.; Postawa, Zbigniew [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Kraków (Poland)

    2013-05-15

    Molecular dynamics simulations of repetitive bombardment of solids by keV cluster beams have generated so much data that easy interpretations are not possible. Moreover, although the MD simulations remove 3–4 nm of material, that is not sufficient material to determine a depth profile. The recently developed steady-state statistical sputtering model (SS-SSM) uses information from the MD simulations and incorporates it into a set of differential equations to predict a depth profile. In this study the distributions that provide the input to the SS-SSM are compared for simulations of 15 keV bombardment of Ag(1 1 1) by C{sub 60}, Au{sub 3} and Ar{sub 872} cluster beams.

  12. Computer simulation of the bombardment of a copper film on graphene with argon clusters

    Institute of Scientific and Technical Information of China (English)

    A. Y. Galashev; O.R. Rakhmanova

    2015-01-01

    The process of graphene clean of copper film by bombarding of Ar13 clusters is investigated by the method of molec-ular dynamics. The kinetic energies of clusters are 5, 10, 20, and 30 eV and incident angles areθ=90◦, 75◦, 60◦, 45◦, and 0◦. It is obtained that the cluster energy should be in the interval 20 eV–30 eV for effective graphene cleaning. There is no cleaning effect at vertical incidence (θ =0◦) of Ar13 clusters. The bombardments at 45◦ and 90◦ incident angles are the most effective ones at a moderate and large amount of deposited copper respectively.

  13. Study of ion beam induced depolymerization using positron annihilation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Puglisi, O. E-mail: opuglisi@dipchi.unict.it; Fragala, M.E.; Lynn, K.G.; Petkov, M.; Weber, M.; Somoza, A.; Dupasquier, A.; Quasso, F

    2001-04-01

    Ion beam induced depolymerization of polymers is a special class of ion beam induced chemical reaction which gives rise to catastrophic 'unzipping' of macromolecules with production of large amounts of the monomer, of the order of many hundreds monomer molecules per each macromolecule. The possible modification of the density at microscopic level prompted us to undertake a study of this effect utilizing positron annihilation techniques in Poly(methylmethacrylate) (PMMA) before and after bombardment with He{sup +} 300 keV ions at 200 deg. C. Preliminary results shown here indicate that before bombardment there is a reproducible dependence of nano-hole distribution on the sample history. Moreover at 200 deg. C we do not detect formation of new cavities as a consequence of the strong depolymerization that occurs under the ion beam. The possible correlation of these findings with transport properties of PMMA at temperature higher than the glass transition temperature will be discussed.

  14. Directional emission of nonthermal halogen atoms by electron bombardment of alkali halides

    Energy Technology Data Exchange (ETDEWEB)

    Postawa, Z.; Szymonski, M.

    1989-06-15

    We present the first experimental results on angle-resolved kinetic-energydistributions of halogen atoms desorbed from single crystals of alkali halidesbecause of electron bombardment. We found that the ejection of nonthermal Bratoms from the (100) surface of KBr is strongly forward peaked along thenormal. We suggest that this effect is caused by a thin damaged layer on thesurface due to a strong nonstoichiometry of the erosion process itself.

  15. Silkworm eggs: An ideal model for studying the biological effects of low energy Ar{sup +} ion interaction in animals

    Energy Technology Data Exchange (ETDEWEB)

    Ling Lin; Liu Xuelan [School of Life Sciences, Anhui Agricultural University, Hefei 230031 (China); Xu Jiaping, E-mail: jiapingxu@163.com [School of Life Sciences, Anhui Agricultural University, Hefei 230031 (China); You Zhengying; Zhou Jingbo [School of Life Sciences, Anhui Agricultural University, Hefei 230031 (China)

    2011-09-15

    Highlights: {yields} Low energy Ar{sup +} ion beam interactions with silkworm eggs. {yields} Ion beam bombardment as a novel method for gene transfer in silkworm. {yields} Provide evidence for studying the mechanisms of ion beam interaction in animals. - Abstract: The object of the current work was to study low energy Ar{sup +} ion beam interactions with silkworm eggs and thus provide further understanding of the mechanisms involved in ion bombardment-induced direct gene transfer into silkworm eggs. In this paper, using low-energy Ar{sup +} ion beam bombardment combined with piggyBac transposon, we developed a novel method to induce gene transfer in silkworm. Using bombardment conditions optimized for egg-incubation (25 keV with ion fluences of 800 x 2.6 x 10{sup 15} ions/cm{sup 2} in dry state under vacuum), vector pBac{l_brace}3 x P3-EGFPaf{r_brace} and helper plasmid pHA3pig were successfully transferred into the silkworm eggs. Our results obtained from by PCR assay and genomic Southern blotting analysis of the G1 generations provide evidence that low-energy ion beam can generate some craters that play a role in acting as pathways of exogenous DNA molecules into silkworm eggs.

  16. Transgenic peanut plants obtained by particle bombardment via somatic embryogenesis regeneration system

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    After pre-culture and treatment of osmosis,cotyledons of immature peanut(Arachis hypogaea L.)zygotic embryos were transformed via particle bombardment with a plasmid containing a chimeric hph gene conferring resistance to hygromycin and a chimeric intron-gus gene.Selection for hygromycin resistant calluses and somatic embryos was initiated at 10th d post-bombardment on medium containing 10-25 mg/L hygromycin.Under continuous selection,hygromycin resistant plantlets were regenerated from somatic embryos and were recovered from nearly 1.6% of the bombarded cotyledons.The presence and integration of foreign DNA in regenerated hygromycin resistant plants was confirmed by PCR(polymerase chain reaction)for the intron-gus gene and by Southern hybridization of the hph gene.GUS enzyme activity was detected in leaflets from transgenic plants but not from control,non-transformed plants.The production of transgenic plants are mainly based on a newly improved somatic embryogenesis regeneration system developed by us.

  17. Effects of xe post-bombardment on carbonitrides produced in a low-carbon nitrogen-implanted steel

    OpenAIRE

    Amaral, Livio; Ramos, Stella Maris Moura; Vasquez, Adalberto; Zawislak, Fernando Claudio; Behar, Moni

    1990-01-01

    The effects of Xe bombardment on carbonitrides produced by N implantation in a low-carbon steel are studied via conversion electron Mossbauer spectroscopy and nuclear reaction analysis. The results show two main features: dissolution and reprecipitation of the produced carbonitrides and modification of the thermal behavior of the precipitates. Recently we have performed similar experiments bombarding samples of the same steel with He and Ar. Comparison of the experiments shows that irradiatio...

  18. Efficiency of position sensitive PPAC for various ions

    CERN Document Server

    Hua Hui; Li Xiang Qing; Qian Tao; Wu He Yu; JinGenMing; Tan Ji Lian; Zhan Wen Long; Duan Li Min; Xiao Zhi Guang; Guo Zhong Yan; Li Zu Yu; Wang Hong Wei; Wang Shu Fan

    2002-01-01

    The detection efficiencies of a position sensitive parallel plate avalanche counter, measured with 40 MeV/u sup 1 sup 7 N beam bombarding on a 621 mg/cm sup 2 sup 1 sup 9 sup 7 Au target, were observed to be significantly different for different ions from helium to oxygen. Furthermore, for a given type of ion, the efficiency decreases with the increase of the incident energy.

  19. Attempts to produce superheavy elements by fusion of /sup 48/Ca with /sup 248/Cm in the bombarding energy range of 4. 5--5. 2 MeV/u

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, P.; Agarwal, Y.K.; Bruechle, W.; Bruegger, M.; Dufour, J.P.; Gaggeler, H.; Hessberger, F.P.; Hofmann, S.; Lemmertz, P.; Muenzenberg, G.; Poppensieker, K.; Reisdorf, W.; Schadel, M.; Schmidt, K.; Schneider, J.H.R.; Schneider, W.F.W.; Suemmerer, K.; Vermeulen, D.; Wirth, a.G.; Ghiorso, A.; Gregorich, K.E.; Lee, D.; Leino, M.; Moody, K.J.; Seaborg, G.T.; Welch, R.B.; Wilmarth, P.; Yashita, S.; Frink, C.; Greulich, N.; Herrmann, G.; Hickmann, U.; Hildebrand, N.; Kratz, J.V.; Trautman, N.; Fowler, M.M.; Hoffman, D.C.; Daniels, W.R.; von Gunten, H.R.; Dornhoefer, H.

    1985-02-04

    A search for superheavy elements was made in bombardments of /sup 248/Cm with /sup 48/Ca ions performed at projectile energies close to the interaction barrier in order to keep the excitation energy of the compound nucleus Z = 116, A = 296 as low as possible. No evidence for superheavy nuclei was obtained in a half-life region from 1 ..mu..s to 10 yr with a production cross section greater than 10/sup -34/ to 10/sup -35/ cm/sup 2/. .AE

  20. Asteroid 4 Vesta: Dynamical and collisional evolution during the Late Heavy Bombardment

    Science.gov (United States)

    Pirani, S.; Turrini, D.

    2016-06-01

    Asteroid 4 Vesta is the only currently identified asteroid for which we possess samples in the form of meteorites. These meteorites revealed us that Vesta is a differentiated body and that its differentiation produced a relatively thin basaltic crust that survived intact over its entire collisional history. The survival of the vestan basaltic crust has long been identified as a pivotal constraint in the study of the evolution of the asteroid belt and the Solar System but, while we possess a reasonably good picture of the effects of the last 4 Ga on such a crust, little is known about the effects of earlier events like the Late Heavy Bombardment. In this work we address this gap in our knowledge by simulating the Late Heavy Bombardment on Vesta in the different dynamical scenarios proposed for the migration of the giant planets in the broad framework of the Nice Model. The results of the simulations allowed us to assess the collisional history of the asteroid during the Late Heavy Bombardment in terms of produced crater population, surface saturation, mass loss and mass gain of Vesta and number of energetic or catastrophic impacts. Our results reveal that planet-planet scattering is a dynamically favorable migration mechanism for the survival of Vesta and its crust. The number of impacts of asteroids larger than about 1 km in diameter estimated as due to the LHB is 31 ± 5, i.e. about 5 times larger than the number of impacts that would have occurred in an unperturbed main belt in the same time interval. The contribution of a possible extended belt to the collisional evolution of Vesta during the LHB is quite limited and can be quantified in 2 ± 1 impacts of asteroids with diameter greater than or equal to 1 km. The chance of energetic and catastrophic impacts is less than 10% and is compatible with the absence of giant craters dated back to 4 Ga ago and with the survival of the asteroid during the Late Heavy Bombardment. The mass loss caused by the bombardment

  1. Ion-induced desorption from stainless-steel vacuum chambers has been studied with a view to improving the dynamic pressure in the future LEIR ion accumulator ring for the LHC.

    CERN Multimedia

    Brice Maximilien

    2002-01-01

    This picture shows part of a vacuum chamber fully equipped with St707 non-evaporable getter (NEG) strips which were bombarded in Linac3 with lead ions at 4.2 MeV/u. A change of the surface morphology is visible where the Pb53+ ions impacted under grazing incidence onto the NEG.

  2. Substrate bias effect on crystallinity of polycrystalline silicon thin films prepared by pulsed ion-beam evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Fazlat; Gunji, Michiharu; Yang, Sung-Chae; Suzuki, Tsuneo; Suematsu, Hisayuki; Jiang, Weihua; Yatsui, Kiyoshi [Nagaoka Univ. of Technology, Extreme Energy-Density Research Inst., Nagaoka, Niigata (Japan)

    2002-06-01

    The deposition of polycrystalline silicon thin films has been tried by a pulsed ion-beam evaporation method, where high crystallinity and deposition rate have been achieved without heating the substrate. The crystallinity and the deposition rate were improved by applying bias voltage to the substrate, where instantaneous substrate heating might have occurred by ion-bombardment. (author)

  3. Neutron distribution and yield produced by 50 MeV/u 18O-ion on thick targets

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Neutron energy, fluence rate, angular distributions anddose equivalent rate distributions around the thick Be, Cu,Au targets bombarded by 50 MeV/u 18O-ion were measured usinga threshold detector activation method. At the same time, theneutron yields of 18O-ion and the neutron emission rates inthe forward direction were obtained approximately.

  4. N(50) Crater Retention Ages for an Expanded Inventory of Lunar Basins: Evidence for an Early Heavy Bombardment and a Late Heavy Bombardment?

    Science.gov (United States)

    Frey, Herbert; Burgess, Emily

    2012-01-01

    LOLA topography and LOLA-derived crustal thickness data provide evidence for a population of impact basins on the Moon that is likely a factor 2 larger than the classical lists based on photogeology. Frey (2012) determined N(50) crater retention ages (CRAs) for 83 candidate basins > 300 km in diameter by counting LOLA-identified craters superimposed over the whole area of the basins. For some basins identified in topography or model crustal thickness it is not possible to unambiguously identify the crater rim as is traditionally done. Also, Quasi-Circular Depressions (QCDs) > 50 km in diameter are recognizable in the mare-filled centers of many basins. Even though these are not apparent in image data, they likely represent buried impact craters superimposed on the basin floor prior to mare infilling and so should be counted in determining the age of the basin. Including these as well as the entire area of the basins improves the statistics, though the error bars are still large when using only craters > 50 km in diameter. The distribution of N(50) CRAs had two distinct peaks which did not depend on whether the basins were named (based on photogeology) or recognized first in topography or crustal thickness data. It also did not depend on basin diameters (both larger and smaller basins made up both peaks) and both peaks persisted even when weaker candidates were excluded. Burgess (2012, unpublished data) redid the counts for 85 basins but improved on the earlier effort by adjusting the counting area where basins overlap. The two peak distribution of N(50) ages was confirmed, with a younger peak at N(50) 40-50 and an older peak at N(50) 80-90 (craters > 50 km diameter per million square km). We suggest this could represent two distinct populations of impactors on the Moon: one producing an Early Heavy Bombardment (EHB) that predates Nectaris and the second responsible for the more widely recognized Late Heavy Bombardment (LHB).

  5. Polishing superhard material surfaces with gas-cluster ion beams

    Science.gov (United States)

    Ieshkin, A. E.; Kushkina, K. D.; Kireev, D. S.; Ermakov, Yu. A.; Chernysh, V. S.

    2017-01-01

    We have studied the influence of bombardment with accelerated gas-cluster ions on the surface topography of silicon carbide and diamond. Atomic-force microscopy shows that exposure to 10-keV gas-cluster ions at a total dose above 1016 cm-2 leads to smoothing of the surface relief. The ion-etching rate and efficiency of the surface relief smoothing as dependent on the thickness of removed layer have been estimated. Raman-spectroscopy data show that surface irradiation with gas-cluster ions does not introduce defects into the crystalline structure of irradiated material.

  6. Ion Beam Assisted Deposition Of Optical Thin Films - Recent Results

    Science.gov (United States)

    McNally, J. J.; Al-Jumaily, G. A.; Wilson, S. R.; McNeil, J. R.

    1985-11-01

    We have examined the properties of dielectric (Ti02, Si02, -Al203, Ta205 and Hf02) films deposited using ion-assisted deposition (IAD). The films were characterized using an angularly resolved scatterometer, spectrophotometer and Raman spectroscopy. A reduction in optical scatter, especially that due to low spatial frequencies, is observed for films deposited with simultaneous ion bombardment. Higher values of refractive index are obtained for films deposited using IAD. Raman spectra indicate a crystalline phase change in TiO2 films is induced by bombardment of samples with 02 ions during deposition. Other experimental data and the effects of the induced phase transition on the optical properties of TiO2 will be discussed.

  7. Simulation study of secondary electron images in scanning ion microscopy

    CERN Document Server

    Ohya, K

    2003-01-01

    The target atomic number, Z sub 2 , dependence of secondary electron yield is simulated by applying a Monte Carlo code for 17 species of metals bombarded by Ga ions and electrons in order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM). In addition to the remarkable reversal of the Z sub 2 dependence between the Ga ion and electron bombardment, a fine structure, which is correlated to the density of the conduction band electrons in the metal, is calculated for both. The brightness changes of the secondary electron images in SIM and SEM are simulated using Au and Al surfaces adjacent to each other. The results indicate that the image contrast in SIM is much more sensitive to the material species and is clearer than that for SEM. The origin of the difference between SIM and SEM comes from the difference in the lateral distribution of secondary electrons excited within the escape depth.

  8. Cosmic Bombardment IV: Averting catastrophe in the here-and-now

    Energy Technology Data Exchange (ETDEWEB)

    Wood, L.; Hyde, R.; Ishikawa, M.; Ledebuhr, A.

    1994-09-23

    At the present time, it is at least arguable that large-scale cosmic bombardment has been a major driver of the evolution of the terrestrialbiosphere. The fundamental motivation of the present paper is the (high) likelihood that the advent and rise of the human species hasn`t coincided with the cessation of soft and hard collisions in the Asteroid Belt or in the Oort Cloud, and that we will either stop the cosmic bombardment or it will eventually stop us. In the foregoing, briefly reviewed the prospects for active planetary defenses against cosmic bombardment in the very near-term, employing only technologies which exist now and could be brought-to-bear in a defensive system on a one-decade time-scale. We sketch various means and mechanisms from a physicist`s viewpoint by which such defensive systems might detect threat objects, launch interdiction machinery toward them and operate such machinery in their vicinity to alternately deflect, disperse or vaporize objects in the 0.1-10 km-diameter range, the ones whose size and population constitute the greatest threats to our biosphere. We conclude that active defenses of all types are readily feasible against 0.1 kmdiameter incoming cosmic bomblets and that even complete vaporization-class defenses are feasible against 1 km-diameter class objects of all compositions. When facing Great Extinctors of up to 10 km diameter, the feasible defensive methods depend upon the object`s size and composition. Dispersion defenses are feasible against all threat-classes, as are deflection approaches for bomblets up to {approximately} 10 km diameter; vaporization-level protection is, however, available only against dirty snowballs` of the {approximately} 1--2 km diameter class. Great Extinctors of sizes significantly greater than 10 km diameter challenge contemporary human technology ever more severely; fortunately, they appear to be rare on the several Aeon time-scales over which Sol will shift its spectral class.

  9. Ion tracking in photocathode rf guns

    Directory of Open Access Journals (Sweden)

    John W. Lewellen

    2002-02-01

    Full Text Available Projected next-generation linac-based light sources, such as PERL or the TESLA free-electron laser, generally assume, as essential components of their injector complexes, long-pulse photocathode rf electron guns. These guns, due to their design rf pulse durations of many milliseconds to continuous wave, may be more susceptible to ion bombardment damage of their cathodes than conventional rf guns, which typically use rf pulses of microsecond duration. This paper explores this possibility in terms of ion propagation within the gun, and presents a basis for future study of the subject.

  10. Aspects of Metal Surface Glowing Mechanisms with Intensive Electron Beam Bombardment

    Directory of Open Access Journals (Sweden)

    I.V. Barsuk

    2012-06-01

    Full Text Available The paper gives a brief description and analysis of the main physical processes which can have an effect on the glowing nature of metal element surfaces in different electric vacuum devices when they are bombarded by electron beams. It has been found that the electron glowing effects on metal surfaces according to the electron energy can be explained with the help of the transition scattering on plasma waves or just with the classical transition radiation effect. This fact is rather important in terms of classical physics interpretation of the observed glowing effects on metal surface elements and techniques optimization of metal and electron beams diagnostics as well.

  11. Evaluation of secondary ion yield enhancement from polymer material by using TOF-SIMS equipped with a gold cluster ion source

    Energy Technology Data Exchange (ETDEWEB)

    Aimoto, K. [Department of Applied Physics, Faculty of Engineering, Seikei University, 3-3-1 Kichijioji-Kitamachi, Musashino-shi, Tokyo 180-8633 (Japan)]. E-mail: dm053502@cc.seikei.ac.jp; Aoyagi, S. [Department of Regional Development, Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu-cho, Matsue-shi, Shimane 690-8504 (Japan); Kato, N. [Department of Applied Physics, Faculty of Engineering, Seikei University, 3-3-1 Kichijioji-Kitamachi, Musashino-shi, Tokyo 180-8633 (Japan); Iida, N. [ULVAC-PHI, Inc., 370 Enzo, Chigasaki, Kanagawa 253-0084 (Japan); Yamamoto, A. [ULVAC-PHI, Inc., 370 Enzo, Chigasaki, Kanagawa 253-0084 (Japan); Kudo, M. [Department of Applied Physics, Faculty of Engineering, Seikei University, 3-3-1 Kichijioji-Kitamachi, Musashino-shi, Tokyo 180-8633 (Japan)

    2006-07-30

    We investigated the enhancement of the secondary ion intensity in the TOF-SIMS spectra obtained by Au{sup +} and Au{sub 3} {sup +} bombardment in comparison with Ga{sup +} excitation using polymer samples with different molecular weight distributions. Since the polymer samples used in this experiment have a wide molecular weight distribution, the advantages of the gold cluster primary ion source over monoatomic ion could accurately be evaluated. It was observed that the degree of fragmentation decreased by the usage of cluster primary ion beam compared with monoatomic ion beam, which was observed as a shift of the intensity distribution in the spectra. It was also found out that the mass effect of Au{sup +} and Ga{sup +} as monoatomic primary ion, resulted in about 10-60 times of enhancement for both samples with different molecular distributions. On the other hand, the Au{sub 3} {sup +} bombardment caused intensity enhancement about 100-2600 compared with Ga{sup +} bombardment, depending on the mass range of the detected secondary ion species. The cluster primary ion effect of Au{sub 3} {sup +}, compared with Au{sup +}, therefore, was estimated to be about 10-45.

  12. Enhanced field emission from compound emitters of carbon nanotubes and ZnO tetrapods by electron beam bombardment.

    Science.gov (United States)

    Wei, Lei; Zhang, Xiaobing; Lou, Chaogang; Zhao, Zhiwei; Jing, Chen; Wang, Baoping

    2011-06-01

    The enhancement of field emission from compound emitters of carbon nanotubes and ZnO tetrapods by the electron beam bombardment is reported. After 20 minutes electron bombardment with 6 keV energy, a few bird-nest micro structures are formed in the compound emitters array. As the simulation results shown, the electric field and field emission current density at the tip of ZnO tetrapod are increased due to the influences of these bird-nest micro structures. From the measurement of the field emission performance, it can be seen that the turn-on electric field and threshold electric field of the field emitter array decrease to 0.4 V/microm and 2.4 V/microm respectively. They have decreased 62% and 15% after the electron bombardment. After the electron bombardment, the emission sites density is increased. The field emission images show that the uniformity of field emission has been improved obviously after the proper electron bombardment. The methodology proposed in this paper has a promising application in the field emission devices.

  13. Scanning electron microscopy of the surfaces of ion implanted SiC

    Energy Technology Data Exchange (ETDEWEB)

    Malherbe, Johan B., E-mail: johan.malherbe@up.ac.za [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Berg, N.G. van der; Kuhudzai, R.J.; Hlatshwayo, T.T.; Thabethe, T.T.; Odutemowo, O.S.; Theron, C.C.; Friedland, E. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Botha, A.J. [Laboratory for Microscopy & Microanalysis, University of Pretoria, Pretoria 0002 (South Africa); Wendler, E. [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, 07743 Jena (Germany)

    2015-07-01

    This paper gives a brief review of radiation damage caused by particle (ions and neutrons) bombardment in SiC at different temperatures, and its annealing, with an expanded discussion on the effects occurring on the surface. The surface effects were observed using SEM (scanning electron microscopy) with an in-lens detector and EBSD (electron backscatter diffraction). Two substrates were used, viz. single crystalline 6H-SiC wafers and polycrystalline SiC, where the majority of the crystallites were 3C-SiC. The surface modification of the SiC samples by 360 keV ion bombardment was studied at temperatures below (i.e. room temperature), just at (i.e. 350 °C), or above (i.e. 600 °C) the critical temperature for amorphization of SiC. For bombardment at a temperature at about the critical temperature an extra step, viz. post-bombardment annealing, was needed to ascertain the microstructure of bombarded layer. Another aspect investigated was the effect of annealing of samples with an ion bombardment-induced amorphous layer on a 6H-SiC substrate. SEM could detect that this layer started to crystalize at 900 °C. The resulting topography exhibited a dependence on the ion species. EBSD showed that the crystallites forming in the amorphized layer were 3C-SiC and not 6H-SiC as the substrate. The investigations also pointed out the behaviour of the epitaxial regrowth of the amorphous layer from the 6H-SiC interface.

  14. Ion irradiation induced direct damage to DNA

    CERN Document Server

    Wang, Wei; Su, Wenhui

    2008-01-01

    Ion beams have been widely applied in a few biological research fields such as radioactive breeding, health protection, and tumor therapy. Up to now many interesting and impressive achievements in biology and agriculture have been made. Over the past several decades, scientists in biology, physics, and chemistry have pursued investigations focused on understanding the mechanisms of these radiobiological effects of ion beams. From the chemical point of view, these effects are due to the ion irradiation induced biomolecular damage, direct or indirect. In this review, we will present a chemical overview of the direct effects of ion irradiation upon DNA and its components, based on a review of literature combined with recent experimental results. It is suggested that, under ion bombardment, a DNA molecule undergoes a variety of processes, including radical formation, atomic displacement, intramolecular bond-scissions, emission of fragments, fragment recombination and molecular crosslink, which may lead to genetic...

  15. Ion beam technology applications study. [ion impact, implantation, and surface finishing

    Science.gov (United States)

    Sellen, J. M., Jr.; Zafran, S.; Komatsu, G. K.

    1978-01-01

    Specific perceptions and possible ion beam technology applications were obtained as a result of a literature search and contact interviews with various institutions and individuals which took place over a 5-month period. The use of broad beam electron bombardment ion sources is assessed for materials deposition, removal, and alteration. Special techniques examined include: (1) cleaning, cutting, and texturing for surface treatment; (2) crosslinking of polymers, stress relief in deposited layers, and the creation of defect states in crystalline material by ion impact; and (3) ion implantation during epitaxial growth and the deposition of neutral materials sputtered by the ion beam. The aspects, advantages, and disadvantages of ion beam technology and the competitive role of alternative technologies are discussed.

  16. H-atom bombardment of CO2, HCOOH and CH3CHO containing ices

    CERN Document Server

    Bisschop, S E; Van Dishoeck, E F; Linnartz, H

    2007-01-01

    Context: Hydrogenation reactions are expected to be among the most important surface reactions on interstellar ices. However, solid state astrochemical laboratory data on reactions of H-atoms with common interstellar ice constituents are largely lacking. Aims: The goal of our laboratory work is to determine whether and how carbon dioxide (CO2), formic acid (HCOOH) and acetaldehyde (CH3CHO) react with H-atoms in the solid state at low temperatures and to derive reaction rates and production yields. Methods: Pure CO2, HCOOH and CH3CHO interstellar ice analogues are bombarded by H-atoms in an ultra-high vacuum experiment. The ices are monitored by reflection absorption infrared spectroscopy and the reaction products are detected in the gas phase through temperature programmed desorption to determine the destruction and formation yields as well as the corresponding reaction rates. Results: Within the sensitivity of our set-up we conclude that H-atom bombardment of pure CO2 and HCOOH ice does not result in detecta...

  17. The effects of energetic proton bombardment on polymeric materials: Experimental studies and degradation models

    Science.gov (United States)

    Coulter, D. R.; Gupta, A.; Smith, M. V.; Fornes, R. E.

    1986-01-01

    This report describes 3 MeV proton bombardment experiments on several polymeric materials of interest to NASA carried out on the Tandem Van De Graff Accelerator at the California Institute of Technology's Kellogg Radiation Laboratory. Model aromatic and aliphatic polymers such as poly(1-vinyl naphthalene) and poly(methyl methacrylate), as well as polymers for near term space applications such as Kapton, Epoxy and Polysulfone, have been included in this study. Chemical and physical characterization of the damage products have been carried out in order to develop a model of the interaction of these polymers with the incident proton beam. The proton bombardment methodology developed at the Jet Propulsion Laboratory and reported here is part of an ongoing study on the effects of space radiation on polymeric materials. The report is intended to provide an overview of the mechanistic, as well as the technical and experimental, issues involved in such work rather than to serve as an exhaustive description of all the results.

  18. Effect of straining graphene on nanopore creation using Si cluster bombardment: A reactive atomistic investigation

    Science.gov (United States)

    Berdiyorov, G. R.; Mortazavi, B.; Ahzi, S.; Peeters, F. M.; Khraisheh, M. K.

    2016-12-01

    Graphene nanosheets have recently received a revival of interest as a new class of ultrathin, high-flux, and energy-efficient sieving membranes because of their unique two-dimensional and atomically thin structure, good flexibility, and outstanding mechanical properties. However, for practical applications of graphene for advanced water purification and desalination technologies, the creation of well controlled, high-density, and subnanometer diameter pores becomes a key factor. Here, we conduct reactive force-field molecular dynamics simulations to study the effect of external strain on nanopore creation in the suspended graphene by bombardment with Si clusters. Depending on the size and energy of the clusters, different kinds of topography were observed in the graphene sheet. In all the considered conditions, tensile strain results in the creation of nanopores with regular shape and smooth edges. On the contrary, compressive strain increases the elastic response of graphene to irradiation that leads to the formation of net-like defective structures with predominantly carbon atom chains. Our findings show the possibility of creating controlled nanopores in strained graphene by bombardment with Si clusters.

  19. Comparative analysis of transgenic tall fescue (Festuca arundinacea Schreb.) plants obtained by Agrobacterium-mediated transformation and particle bombardment.

    Science.gov (United States)

    Gao, Caixia; Long, Danfeng; Lenk, Ingo; Nielsen, Klaus Kristian

    2008-10-01

    Agrobacterium-mediated transformation and particle bombardment are the two most widely used methods for genetically modifying grasses. Here, these two systems are compared for transformation efficiency, transgene integration and transgene expression when used to transform tall fescue (Festuca arundinacea Schreb.). The bar gene was used as a selectable marker and selection during tissue culture was performed using 2 mg/l bialaphos in both callus induction and regeneration media. Average transformation efficiency across the four callus lines used in the experiments was 10.5% for Agrobacterium-mediated transformation and 11.5% for particle bombardment. Similar transgene integration patterns and co-integration frequencies of bar and uidA were observed in both gene transfer systems. However, while GUS activity was detected in leaves of 53% of the Agrobacterium transformed lines, only 20% of the bombarded lines showed GUS activity. Thus, Agrobacterium-mediated transformation appears to be the preferred method for producing transgenic tall fescue plants.

  20. Chemical Bonding States of TiC Films before and after Hydrogen Ion Irradiation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    TiC films deposited by rf magnetron sputtering followed by Ar+ ion bombardment were irradiated with a hydrogen ion beam. X-ray photoelectron spectroscopy (XPS) was used for characterization of the chemical bonding states of C and Ti elements of the TiC films before and after hydrogen ion irradiation, in order to understand the effect of hydrogen ion irradiation on the films and to study the mechanism of hydrogen resistance of TiC films. Conclusions can be drawn that ion bombardment at moderate energy can cause preferential physical sputtering of carbon atoms from the surface of low atomic number (Z) material. This means that ion beam bombardment leads to the formation of a non-stoichiometric composition of TiC on the surface.TiC films prepared by ion beam mixing have the more excellent characteristic of hydrogen resistance. One important cause, in addition to TiC itself, is that there are many vacant sites in TiC created by ion beam mixing.These defects can easily trap hydrogen and effectively enhance the effect of hydrogen resistance.

  1. Deep-level transient spectroscopy of low-energy ion-irradiated silicon

    DEFF Research Database (Denmark)

    Kolkovsky, Vladimir; Privitera, V.; Nylandsted Larsen, Arne

    2009-01-01

     During electron-gun deposition of metal layers on semiconductors, the semiconductor is bombarded with low-energy metal ions creating defects in the outermost surface layer. For many years, it has been a puzzle why deep-level transient spectroscopy spectra of the as-deposited, electron-gun...

  2. Neutrons produced by 75MeV/u 12C—ion on thick targets

    Institute of Scientific and Technical Information of China (English)

    LiGisheng; ZHANGTianmei; 等

    1999-01-01

    Fluence rates and angular distributions of the neutron emitted by 75MeV/u 12C-ion bombardment on thick Be and Au targets have been measured by means of the threshold detector activation method.Based on that,the neutron yields,emission rates in the forward direction and neutron dose equivalent rate distributions were deduced.

  3. Measurement of ultra-low ion energy of decelerated ion beam using a deflecting electric field

    Energy Technology Data Exchange (ETDEWEB)

    Thopan, P.; Suwannakachorn, D.; Tippawan, U. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2015-12-15

    In investigation on ultra-low-energy ion bombardment effect on DNA, an ion beam deceleration lens was developed for high-quality ultra-low-energy ion beam. Measurement of the ion energy after deceleration was necessary to confirm the ion beam really decelerated as theoretically predicted. In contrast to conventional methods, this work used a simple deflecting electrostatic field after the deceleration lens to bend the ion beam. The beam bending distance depended on the ion energy and was described and simulated. A system for the measurement of the ion beam energy was constructed. It consisted of a pair of parallel electrode plates to generate the deflecting electrical field, a copper rod measurement piece to detect ion beam current, a vernier caliper to mark the beam position, a stepping motor to translate the measurement rod, and a webcam-camera to read the beam bending distance. The entire system was installed after the ion-beam deceleration lens inside the large chamber of the bioengineering vertical ion beam line. Moving the measurement rod across the decelerated ion beam enabled to obtain beam profiles, from which the beam bending distance could be known and the ion beam energy could be calculated. The measurement results were in good agreement with theoretical and simulated results.

  4. Measurement of ultra-low ion energy of decelerated ion beam using a deflecting electric field

    Science.gov (United States)

    Thopan, P.; Suwannakachorn, D.; Tippawan, U.; Yu, L. D.

    2015-12-01

    In investigation on ultra-low-energy ion bombardment effect on DNA, an ion beam deceleration lens was developed for high-quality ultra-low-energy ion beam. Measurement of the ion energy after deceleration was necessary to confirm the ion beam really decelerated as theoretically predicted. In contrast to conventional methods, this work used a simple deflecting electrostatic field after the deceleration lens to bend the ion beam. The beam bending distance depended on the ion energy and was described and simulated. A system for the measurement of the ion beam energy was constructed. It consisted of a pair of parallel electrode plates to generate the deflecting electrical field, a copper rod measurement piece to detect ion beam current, a vernier caliper to mark the beam position, a stepping motor to translate the measurement rod, and a webcam-camera to read the beam bending distance. The entire system was installed after the ion-beam deceleration lens inside the large chamber of the bioengineering vertical ion beam line. Moving the measurement rod across the decelerated ion beam enabled to obtain beam profiles, from which the beam bending distance could be known and the ion beam energy could be calculated. The measurement results were in good agreement with theoretical and simulated results.

  5. Early Solar System Bombardment: Exploring the Echos of Planetary Migration and Lost Ice Giants

    Science.gov (United States)

    Bottke, William

    2017-01-01

    Heavily cratered surfaces on the Moon, Mars, Mercury show the terrestrial planets were battered by an intense bombardment during their first billion years or more, but the timing, sources, and dynamical implications of these impacts are controversial. The Late Heavy Bombardment refers to impact events that occurred after stabilization of planetary lithospheres such that they could be preserved as craters. Lunar melt rocks and meteorite shock ages point toward a discrete episode of elevated impact flux between ~3.5 to ~4.2 Ga and a relative quiescence between ~4.0-4.2 to ~4.4 Ga. Evidence from Precambrian impact spherule layers suggest a long-lived tail of terrestrial impactors lasted to ~2.0-2.5 Ga.Dynamical models that include populations residual from primary accretion and destabilized by giant planet migration can potentially account for observations, although all have pros and cons. The most parsimonious solution to match constraints is a hybrid model with discrete early, post-accretion and later, planetary instability-driven impactor populations.For the latter, giant planet instability models can successfully reproduce the orbits of the giant planets, the origin/properties of Jupiter/Neptune Trojans, irregular satellites, the structure of the main asteroid and Kuiper belts, and the presence of comet-like bodies in the main belt, Hilda, and Trojan asteroid populations. The best solutions, however, postulate there were once five giant planets: Jupiter, Saturn, and three ice giants, one that was eventually ejected out of the Solar System by a Jupiter encounter. Intriguing evidence for this “lost” ice giant planet can be found in the orbital properties of bodies captured in the main asteroid belt.The applicability of giant planet instabilities to exoplanet systems seems likely, with the initial configuration of giant planet orbits a byproduct of their early migration and subsequent capture into mutual mean motion resonances. The question is how long can a

  6. The Bombardment of the Earth During the Hadean and Early Archean Eras

    Science.gov (United States)

    Marchi, S.; Bottke, W. F.; Elkins-Tanton, L. T.; Morbidelli, A.; Wuennemann, K.; Kring, D. A.; Bierhaus, M.

    2013-12-01

    Our knowledge of the Earth during the Hadean and early Archean eons (ca 4.5-3.5 Ga) is very limited, mainly because few rocks older than 3.8 Ga have been found (e.g. Harrison 2009). Hadean-era zircons have allowed us to glean important insights into this era, but their data has led to considerably different evolution models for the evolution of the early Earth; some predict a hellish world dominated by a molten surface with a sporadic steam atmosphere (e.g. Pollack 1997), while others have predicted a tranquil, cool surface with stable oceans (e.g. Wilde et al 2001; Valley et al 2002). To understand whether either model (or both) could be right, we believe it is useful to quantitatively examine the post Moon-forming impact bombardment of the early Earth. Over the last several years, through a combination of observations (e.g., Marchi et al 2012), theoretical models (e.g., Bottke et al 2012), and geochemical constraints from lunar rock (e.g. highly siderophile elements -HSE- abundances delivered to the Moon by impactors; the global number of lunar basins; the record of Archean-era impact spherule beds on Earth; Walker 2009; Neumann et al 2012), we have constructed a calibrated model of the early lunar impactor flux (Morbidelli et al 2012). Our results have now been extrapolated to the Earth, where they can make predictions about its early bombardment. Using a Monte Carlo code to account for the stochastic nature of major impacts, and constraining our results by the estimated HSE abundances of Earth's mantle (that were presumably delivered by impactors; Walker 2009; Bottke et al. 2010), we find the following trends. In the first ~100-200 Myr after the formation of the Moon, which we assume was created ~4.5 Ga, the Earth was almost entirely resurfaced by impacts. This bombardment, which included numerous D > 1000 km diameter impactors, should have vigorously mixed the crust and upper mantle. Between ~4.1-4.3 Ga, the impactor flux steadily decreased; though an uptick

  7. Howard Zinn, La bombe. De l'inutilité des bombardements aériens

    OpenAIRE

    Erbs, Laurent

    2011-01-01

    Avec La bombe, Howard Zinn signe son dernier ouvrage. Historien, intellectuel réputé, engagé au côté des mouvements contestataires américains, Howard Zinn a marqué les consciences grâce à ses écrits critiques sur le pouvoir et ses structures. La bombe reprend un texte original, « Hiroshima : briser le silence », publié en 1995 à l’occasion du 50e anniversaire du bombardement atomique du Japon. L’auteur souhaite y subvertir les discours prônant la nécessité des attaques atomiques contre le Jap...

  8. Photon counting imaging and centroiding with an electron-bombarded CCD using single molecule localisation software

    Science.gov (United States)

    Hirvonen, Liisa M.; Barber, Matthew J.; Suhling, Klaus

    2016-06-01

    Photon event centroiding in photon counting imaging and single-molecule localisation in super-resolution fluorescence microscopy share many traits. Although photon event centroiding has traditionally been performed with simple single-iteration algorithms, we recently reported that iterative fitting algorithms originally developed for single-molecule localisation fluorescence microscopy work very well when applied to centroiding photon events imaged with an MCP-intensified CMOS camera. Here, we have applied these algorithms for centroiding of photon events from an electron-bombarded CCD (EBCCD). We find that centroiding algorithms based on iterative fitting of the photon events yield excellent results and allow fitting of overlapping photon events, a feature not reported before and an important aspect to facilitate an increased count rate and shorter acquisition times.

  9. Influences of edge localized mode-like pulsed plasma bombardment on deuterium retention in tungsten

    Science.gov (United States)

    Nishijima, D.; Kikuchi, Y.; Nakatsuka, M.; Baldwin, M. J.; Doerner, R. P.; Nagata, M.; Ueda, Y.

    2011-12-01

    Deuterium (D) retention in tungsten (W) subjected to pulsed D plasma bombardment (surface absorbed energy density Q ~0.5-0.7 MJ m-2 at ~0.3-0.5 ms) has been investigated in a magnetized coaxial plasma gun. A high temperature desorption peak of D2 appears at ~1000-1100 K following transients at ~0.5 MJ m-2. At a higher Q ~0.7 MJ m-2, the total amount of D retained in W is significantly reduced. Nano-sized helium (He) bubbles, created by steady-state He plasma pre-exposure at ~573 K, slightly lower D retention, while a significant reduction is observed for a W fuzzy surface formed by steady-state high temperature (~1100 K) He plasma pre-exposure.

  10. Radiation in the wavelength range 120-900 nm from keV electron bombardment of solid hydrogens

    DEFF Research Database (Denmark)

    Schou, Jørgen; Stenum, B.; Sørensen, H.

    1991-01-01

    The emission of light from hydrogenic pellet material has been studied in a special experimental set-up. The measurements show that the intensity of light from particle bombarded solid hydrogens is very small and that none of the well known lines for the gas phase are emitted from the solid. The ...

  11. Effect of Ar ion on the surface properties of low density polyethylene

    Science.gov (United States)

    Zaki, M. F.

    2016-04-01

    In this paper, low-density polyethylene (LDPE) was irradiated by argon ion with different fluences up to 1015ions/cm2. The optical, chemical and hardness properties have been investigated using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and micro-indentation tester, respectively. The results showed the ion beam bombardment induced decreases in the transmittance of the irradiated polymer samples. This change in transmittance can be attributed to the formation of conjugated bonds i.e. possible formation of defects and/or carbon clusters. The indirect optical band gap decreased from 3.0 eV for the pristine sample to 2.3 eV for that sample irradiated with the highest fluence of the Ar ion beam. Furthermore, the number of carbon atoms and clusters increased with increasing Ar ion fluences. FTIR spectra showed the formation of new bands of the bombarded polymer samples. Furthermore, polar groups were created on the surface of the irradiated samples which refer to the increase of the hydrophilic nature of the surface of the irradiated samples. The Vicker's hardness increased from 4.9 MPa for the pristine sample to 17.9 MPa for those bombarded at the highest fluence. This increase is attributed to the increase in the crosslinking and alterations of the bombarded surface into hydrogenated amorphous carbon, which improves the hardness of the irradiated samples. The bombarded LDPE surfaces may be used in special applications to the field of the micro-electronic devices and shock absorbers.

  12. Effects of projectile track charging on the H - secondary ion velocity distribution

    Science.gov (United States)

    Iza, P.; Farenzena, L. S.; da Silveira, E. F.

    2007-03-01

    The bombardment of insulating targets by MeV projectiles produces a positive track delivering secondary electrons to the solid. These electrons are eventually captured by adsorbed hydrogen-containing molecules, inducing fragmentation and initiating the H- secondary ion emission. The dynamics of this process is very sensitive to the track electric field and depends on the emission site and on the H- initial velocity. In this work, a model, based on a time-depending track potential followed by secondary electron induced desorption - SEID, is employed to describe the production and dynamics of H- secondary ion emission. It is shown that depending on how fast the track neutralization occurs, the movement of H- ions may be accelerated, decelerated or even aborted. Trajectories, angular distributions and energy distributions are predicted and compared with experimental data obtained for water ice bombarded by 1.7 MeV nitrogen ions.

  13. Fast atom bombardment (FAB) mass spectrometry: a mass spectral investigation of some of the insulins.

    Science.gov (United States)

    Barber, M; Bordoli, R S; Elliott, G J; Tyler, A N; Bill, J C; Green, B N

    1984-04-01

    Mass measurements of the protonated molecules [M + H]+ of four insulins are presented. In addition, structurally significant fragment ions are observed in the mass spectrum and metastable scanning has been used to link these ions to the protonated molecule.

  14. Visualization of heavy ion-induced charge production in a CMOS image sensor

    CERN Document Server

    Végh, J; Klamra, W; Molnár, J; Norlin, LO; Novák, D; Sánchez-Crespo, A; Van der Marel, J; Fenyvesi, A; Valastyan, I; Sipos, A

    2004-01-01

    A commercial CMOS image sensor was irradiated with heavy ion beams in the several MeV energy range. The image sensor is equipped with a standard video output. The data were collected on-line through frame grabbing and analysed off-line after digitisation. It was shown that the response of the image sensor to the heavy ion bombardment varied with the type and energy of the projectiles. The sensor will be used for the CMS Barrel Muon Alignment system.

  15. Effect of inelastic and elastic energy losses of Xe ions on the evolution of hydrogen blisters in silicon

    Science.gov (United States)

    Reutov, V. F.; Dmitriev, S. N.; Sokhatskii, A. S.; Zaluzhnyi, A. G.

    2016-01-01

    We analyze the effect of irradiation by heavy ions on the formation of blisters on the silicon surface preliminarily ion-doped with hydrogen. An attempt is made at differentiating inelastic and elastic processes of interaction between ions and Si atoms using bombardment of the sample with high-energy charged particles through a bent absorbing filter by varying the radiation doses and the energy of bombarding Xe ions. It is found that irrespective of specific ionization energy losses of heavy ions, the blister formation is completely suppressed in the zone of the inelastic interaction during postradiation annealing. Conversely, stimulated development of hydrogen porosity takes place at the same time in the zone of elastic interaction, which is manifested in the form of blisters and flaking.

  16. Influence of energetic ion bombardment on W-C : H coatings deposited with W and WC targets

    NARCIS (Netherlands)

    Strondl, C; Carvalho, NM; De Hosson, JTM; Krug, TG

    2005-01-01

    Tungsten containing diamond-like carbon (W-C:H) coatings have been produced by unbalanced magnetron sputtering using two different target materials. In the first series of coatings, W has been used as target material, and in the second series, WC has been used as target material. In both series of W

  17. Confirming the key role of Ar+ ion bombardment in growth feature of nanostructured carbon materials by PECVD.

    Science.gov (United States)

    Liu, Yulin; Lin, Jinghuang; Jia, Henan; Chen, Shulin; Qi, J; Qu, Chaoqun; Cao, Jian; Feng, Jicai; Fei, Weidong

    2017-09-20

    In order to confirm the key role of plasma etching in growth feature of nanostructured carbon materials (NCMs), here we reported a novel strategy to in-situ create different states of plasma etching conditions in plasma enhanced chemical vapor deposition (PECVD) by separating catalyst film from substrate. Different plasma-related environments on either side of the catalyst film were created simultaneously for achieving multi-layered structural NCMs. Results showed that plasma etching is observed crucial and complex for the growth of NCMs. The effect of plasma etching has both positive and negative sides on carbon nanotubes (CNTs). On one hand, plasma etching can break up the structure of CNTs and thus thin CNTs cannot be obtained. On the other hand, plasma etching can remove the redundant carbon on surface of large catalyst particles, contributing to catalyzing thick CNTs. As a result, the diameter of CNTs depends on the state of plasma etching. For vertically oriented few-layer graphene (VFG), plasma etching is an essential asset and strong plasma etching can even change the CNTs into VFG. Therefore, specific multi-layered structural NCMs can be obtained by PECVD combining plasma etching with catalyst separation method, which is promising in many fields. © 2017 IOP Publishing Ltd.

  18. Ion bombardment effects on nucleation of sputtered Mo nano-crystals in Mo/B4C/Si multilayers

    NARCIS (Netherlands)

    Patelli, A.; Rigato, V.; Salmaso, G.; Carvalho, N. J. M.; De Hosson, J. Th. M.; Bontempi, E.; Depero, L. E.

    2006-01-01

    Over recent years, the introduction of Mo/Si multilayers mirrors with different barrier layers for the interfaces has allowed increasing mirror reflectance, life and temperature stability. The effects of these very thin barrier layers on multilayer growth, such as interlayer formation and Mo crystal

  19. Characterization of carbon contamination under ion and hot atom bombardment in a tin-plasma extreme ultraviolet light source

    NARCIS (Netherlands)

    Dolgov, A.; Lopaev, D.; Lee, C. J.; Zoethout, E.; Medvedev, V.; Yakushev, O.; F. Bijkerk,

    2015-01-01

    Molecular contamination of a grazing incidence collector for extreme ultraviolet (EUV) lithography was experimentally studied. A carbon film was found to have grown under irradiation from a pulsed tin plasma discharge. Our studies show that the film is chemically inert and has characteristics that a

  20. Target development for a radioactive ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, M.; Vanhorenbeeck, J. (Universite Libre de Bruxelles (Belgium). Inst. d' Astronomie et d' Astrophysique); Baeten, F.; Dom, C. (Institut National des Radioelements, Fleurus (Belgium)); Darquennes, D.; Delbar, T.; Jongen, Y.; Lacroix, M.; Lipnik, P.; Loiselet, M.; Ryckewaert, G.; Wa Kitwanga, S.; Vervier, J.; Zaremba, S. (Louvain Univ., Louvain-la-Neuve (Belgium). Centre de Physique Nucleaire; Louvain Univ., Louvain-la-Neuve (Belgium). Lab. de Cyclotron); Huyse, M.; Reusen, G.; Duppen, P. van (Leuven Univ. (Belgium). Inst. voor Kern- en Stralingsfysika)

    1989-10-01

    A proton bombarded target coupled to an ion source is a key-equipment to produce a cyclotron accelerated Radioactive Ion Beam (RIB). This note concerns the target development for a {sup 13}N ion beam which will be the first one out of a more general project at Louvain-la-Neuve (Report RIB-1988-01). A 30-MeV proton beam of up to 300-{mu}A intensity from the CYCLONE 30 bombards a graphite target to produce the {sup 13}N isotope via the {sup 13}C(p, n){sup 13}N reaction. Two major problems have to be solved: The extraction and transport of {sup 13}N and the beam-heat dissipation. These aspects are somewhat correlated to the temperature dependence of the {sup 13}N release and to the heat conductivity of graphite. A disk shaped target can be cooled through its side-face or through its back-face, and in fact both designs are explored. The extraction yield of the first one varies with the beam intensity up to a maximum value of 46% at 170 {mu}A. For the second one, which is presently under development, the target temperature can be adjusted by a cooled finger of variable length. (orig.).

  1. An investigation of secondary ion yield enhancement using Bin2+ (n=1,3,5) primary ions.

    Science.gov (United States)

    Nagy, Gabriella; Lu, Peng; Walker, Amy V

    2008-01-01

    We have investigated secondary ion yield enhancement using Bin2+ (n=1, 3, 5) primary ions impacting phenylalanine, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), cholesterol, Irganox 1010, and polymer films adsorbed on silicon and aluminum. Secondary ion yields are increased using Bi2+and Bi3(2+) primary ions for the molecular layers and polymers that can undergo allyl cation rearrangements. For Irganox 1010, the deprotonated molecular ion yields (m/z 1175; [M-H]-) are one to two times larger for Bi2+ and Bi(3)2+ primary ions than for Bi+ and Bi3+ at the same primary ion velocities. In the positive ion mode, the largest fragment ion yield (m/z 899) is 1.5 times larger for Bi2+ ions than for Bi+. For Bi3(2+) the largest fragment ion yield is only 70% of the ion yield using Bi3+, but the secondary ion yields of the fragment ions at m/z 57 and 219 are enhanced. For polymers that can undergo allyl cation rearrangement reactions the secondary ion yield enhancements of the monomer ions range from 1.3 to 4.3. For Bi(5)2+ primary ions, secondary ion yields were the same or slightly larger than for Bi5+ in the negative ion mass spectra for Irganox 1010, but lower in the positive ion mode. No secondary ion yield enhancements were measured on polymer samples for Bi5(2+). For all polymer films studied, secondary ion intensities from the oligomer regions are substantially decreased using Bin2+ (n=1, 3, 5). We discuss differences in the ionization mechanisms for doubly and singly-charged Bi primary ion bombardment.

  2. Corrosion behavior of low energy, high temperature nitrogen ion-implanted AISI 304 stainless steel

    Indian Academy of Sciences (India)

    M Ghorannevis; A Shokouhy; M M Larijani; S H Haji Hosseini; M Yari; A Anvari; M Gholipur Shahraki; A H Sari; M R Hantehzadeh

    2007-01-01

    This work presents the results of a low-energy nitrogen ion implantation of AISI 304 type stainless steel (SS) at a moderate temperature of about 500° C. The nitrogen ions are extracted from a Kauffman-type ion source at an energy of 30 keV, and ion current density of 100 A cm-2. Nitrogen ion concentration of 6 × 1017, 8 × 1017 and 1018 ions cm-2, were selected for our study. The X-ray diffraction results show the formation of CrN polycrystalline phase after nitrogen bombardment and a change of crystallinity due to the change in nitrogen ion concentration. The secondary ion mass spectrometry (SIMS) results show the formation of CrN phases too. Corrosion test has shown that corrosion resistance is enhanced by increasing nitrogen ion concentration.

  3. Electronic and Optical Properties of Aluminum Oxide Before and After Surface Reduction by Ar+ Bombardment

    Directory of Open Access Journals (Sweden)

    D. Tahir

    2014-08-01

    Full Text Available The electronic and optical properties of a-Al2O3 after induced by 3-keV Ar+ sputtering have been studied quantitatively by use of reflection electron energy loss spectroscopy (REELS spectra. The band gap values of a-Al2O3 was determined from the onset values of the energy loss spectrum to the background level of REELS spectra as a function of time Ar+ bombardment. The bandgap changes from 8.4 eV before sputtering to 6.2 eV after 4 minutes of sputtering.The optical properties of α-Al2O3 thin films have been determined by comparing the experimental cross section obtained from reflection electron energy loss spectroscopy with the theoretical inelastic scattering cross section, deduced from the simulated energy loss function (ELF by using QUEELS-ε(k-REELS software. The peak assignments are based on ELF and compared with reported data on the electronic structure of α-Al2O3 obtained using different techniques. The results demonstrate that the electronic and optical properties before and after surface reduction will provide further understanding in the fundamental properties of α-Al2O3 which will be useful in the design, modeling and analysis of devices applications performance.

  4. Effects of supersonic fine particle bombarding on thermal cyclic failure lifetime of thermal barrier coating

    Institute of Scientific and Technical Information of China (English)

    CHEN Ya-jun; LIN Xiao-ping; WANG Zhi-ping; WANG Li-jun; JI Zhao-hui; DONG Yun

    2010-01-01

    Thermal barrier coating(TBC)consisting of a NiCoCrAlY bond coat(BC)and a ZrO2-8 wt.%Y2O3 topcoat(TC)was fabricated on the nickel-base supcralloy by air plasma spray(APS).The BC was trea-ted by supersonic fine particle bombarding(SFPB).Thermal cyclic failure and residual stress in thermally grown oxide(TGO)scale were studied by SEM with EDS and ruby fluorescence spectroscopy(RFS).As shown in the results,after treated by SFPB,thickening of TGO was relatively slow,which reduced the level of growth stress.The TBC with SFPB treatment was still remained well undergoing 350 times of thermal cycle.However,after thermal cycle with the same times,the separation of TC was observed in TBC without SFPB treatment.The residual stress analysis by RFS showed that the residual stress of SFPB-treated TBC increased with the increasing number of thermal cycle.The residual stress of conventional TBC reached a value of 650MPa at 350 times of cycle and that of SFPB-treated TBC only reached 532 MPa at 400 times of cycle.The BC with SFPB treatment after 400 times of cycle was analyzed by RFS,the high stress value was not observed in local thickened region of TGO.Thermal cycling resistance of TBC can be improved by the SFPB technology.

  5. Are there proteins between the ribosomal subunits? Hot tritium bombardment experiments.

    Science.gov (United States)

    Yusupov, M M; Spirin, A S

    1986-03-03

    The hot tritium bombardment technique [(1976) Dokl. Akad. Nauk SSSR 228, 1237-1238] was used for studying the surface localization of ribosomal proteins on Escherichia coli ribosomes. The degree of tritium labeling of proteins was considered as a measure of their exposure (surface localization). Proteins S1, S4, S7, S9 and/or S11, S12 and/or L20, S13, S18, S20, S21, L5, L6, L7/L12, L10, L11, L16, L17, L24, L26 and L27 were shown to be the most exposed on the ribosome surface. The sets of exposed ribosomal proteins on the surface of 70 S ribosomes, on the one hand, and the surfaces of 50 S and 30 S ribosomal subunits in the dissociated state, on the other, were compared. It was found that the dissociation of ribosomes into subunits did not result in exposure of additional ribosomal proteins. The conclusion was drawn that proteins are absent from the contacting surfaces of the ribosomal subunits.

  6. Constraining the cometary flux through the asteroid belt during the late heavy bombardment

    CERN Document Server

    Brož, M; Bottke, W F; Rozehnal, J; Vokrouhlický, D; Nesvorný, D

    2013-01-01

    In the Nice model, the late heavy bombardment (LHB) is related to an orbital instability of giant planets which causes a fast dynamical dispersion of a transneptunian cometary disk. We study effects produced by these hypothetical cometary projectiles on main-belt asteroids. In particular, we want to check whether the observed collisional families provide a lower or an upper limit for the cometary flux during the LHB. We present an updated list of observed asteroid families as identified in the space of synthetic proper elements by the hierarchical clustering method, colour data, albedo data and dynamical considerations and we estimate their physical parameters. We selected 12 families which may be related to the LHB according to their dynamical ages. We then used collisional models and N-body orbital simulations to gain insight into the long-term dynamical evolution of synthetic LHB families over 4 Gyr. We account for the mutual collisions, the physical disruptions of comets, the Yarkovsky/YORP drift, chaotic...

  7. High-efficiency stable transformation of the model fern species Ceratopteris richardii via microparticle bombardment.

    Science.gov (United States)

    Plackett, Andrew R G; Huang, Liandong; Sanders, Heather L; Langdale, Jane A

    2014-05-01

    Ferns represent the most closely related extant lineage to seed plants. The aquatic fern Ceratopteris richardii has been subject to research for a considerable period of time, but analyses of the genetic programs underpinning developmental processes have been hampered by a large genome size, a lack of available mutants, and an inability to create stable transgenic lines. In this paper, we report a protocol for efficient stable genetic transformation of C. richardii and a closely related species Ceratopteris thalictroides using microparticle bombardment. Indeterminate callus was generated and maintained from the sporophytes of both species using cytokinin treatment. In proof-of-principle experiments, a 35S::β-glucuronidase (GUS) expression cassette was introduced into callus cells via tungsten microparticles, and stable transformants were selected via a linked hygromycin B resistance marker. The presence of the transgene in regenerated plants and in subsequent generations was validated using DNA-blot analysis, reverse transcription-polymerase chain reaction, and GUS staining. GUS staining patterns in most vegetative tissues corresponded with constitutive gene expression. The protocol described in this paper yields transformation efficiencies far greater than those previously published and represents a significant step toward the establishment of a tractable fern genetic model.

  8. Calculated Radioactivity Yields of Cu-64 from Proton-Bombarded Ni-64 Targets Using SRIM Codes

    Directory of Open Access Journals (Sweden)

    I. Kambali

    2014-12-01

    Full Text Available The End-Of-Bombardment (EOB Yields from 64Ni(p,n64Cu nuclear reaction have been calculated for optimizing irradiation parameters that correspond to future 64Cu radionuclide production using the BATAN’s 26.5-MeV cyclotron in Serpong. Enriched Ni target thickness, proton beam current and irradiation time which play significant role in the success of the Positron Emission Tomography (PET radionuclide were also discussed in this paper. For a 26.5-MeV proton beam, the optimum target thickness for 64Cu production was nearly 1.5 mm with yields up to 560 mCi/µA.hr at the end of the irradiation. The comparisons with some selected experimental data indicated that the much-lower-than-expected EOB yields were mainly due to incorrect target thickness prepared for the irradiation. Nevertheless, these calculations were in good agreement with the previous predicted data with a maximum difference of less than 10%. The discrepancies were mostly due to different cross-section data employed in the calculations.

  9. Asteroid 4 Vesta: dynamical and collisional evolution during the Late Heavy Bombardment

    CERN Document Server

    Pirani, S

    2016-01-01

    Vesta is the only currently identified asteroid for which we possess samples, which revealed us that the asteroid is differentiated and possesses a relatively thin basaltic crust that survived to the evolution of the asteroid belt and the Solar System. However, little is know about the effects of past events like the Late Heavy Bombardment on this crust. We address this gap in our knowledge by simulating the LHB in the different dynamical scenarios proposed for the migration of the giant planets in the broad framework of the Nice Model. The results of simulations generate information about produced crater population, surface saturation, mass loss and mass gain of Vesta and number of energetic or catastrophic impacts during LHB. Our results reveal that planet-planet scattering is a dynamically favourable migration mechanism for the survival of Vesta and its crust. The number of impacts on Vesta estimated as due to the LHB is $31\\pm5$, i.e. about 5 times larger than the number of impacts that would have occurre...

  10. Measurements and parameterization of neutron energy spectra from targets bombarded with 120 GeV protons

    Energy Technology Data Exchange (ETDEWEB)

    Kajimoto, T., E-mail: kajimoto@hiroshima-u.ac.jp [Hiroshima University, Kagamiyama, Higashi-hiroshima 739-8527 (Japan); Shigyo, N. [Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Sanami, T. [High Energy Accelerator Research Organization, Oho, Tsukuba, Ibaraki 305-0801 (Japan); Iwamoto, Y. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Hagiwara, M. [High Energy Accelerator Research Organization, Oho, Tsukuba, Ibaraki 305-0801 (Japan); Lee, H.S. [Pohang Accelerator Laboratory, POSTECH, Pohang, Kyungbuk 790-784 (Korea, Republic of); Soha, A.; Ramberg, E.; Coleman, R.; Jensen, D.; Leveling, A.; Mokhov, N.V.; Boehnlein, D.; Vaziri, K. [Fermi National Accelerator Laboratory, Batavia, IL 60510-5011 (United States); Sakamoto, Y. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Ishibashi, K. [Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Nakashima, H. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

    2014-10-15

    Highlights: •Neutron energy spectra from targets bombarded with 120 GeV protons were measured. •The neutron energy was determined with the time-of-flight technique. •The measured spectra were compared with those calculated by PHITS and FLUKA. •Large differences were found between measured and calculated spectra. •The study shows the need to improve models for neutron production in the high energy region. -- Abstract: The energy spectra of neutrons were measured by a time-of-flight method for 120 GeV protons on thick graphite, aluminum, copper, and tungsten targets with an NE213 scintillator at the Fermilab Test Beam Facility. Neutron energy spectra were obtained between 25 and 3000 MeV at emission angles of 30°, 45°, 120°, and 150°. The spectra were parameterized as neutron emissions from three moving sources and then compared with theoretical spectra calculated by PHITS and FLUKA codes. The yields of the theoretical spectra were substantially underestimated compared with the yields of measured spectra. The integrated neutron yields from 25 to 3000 MeV calculated with PHITS code were 16–36% of the experimental yields and those calculated with FLUKA code were 26–57% of the experimental yields for all targets and emission angles.

  11. The Earth-Moon system during the Late Heavy Bombardment period

    CERN Document Server

    Jorgensen, Uffe Graae; Hatsukawa, Yuichi; Frei, Robert; Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi

    2009-01-01

    The Late Heavy Bombardment (LHB) period is the narrow time interval between 3.8 and 3.9 Gyr ago, where the bulk of the craters we see on the Moon formed. Even more craters formed on the Earth. During a field expedition to the 3.8 Gyr old Isua greenstone belt in Greenland, we sampled three types of metasedimentary rocks, that contain direct traces of the LHB impactors by a seven times enrichment (150 ppt) in iridium compared to present day ocean crust (20 ppt). We show that this enrichment is in agreement with the lunar cratering rate, providing the impactors were comets, but not if they were asteroids. Our study is a first direct indication of the nature of the LHB impactors, and the first to find an agreement between the LHB lunar cratering rate and the Earth's early geochemical record (and the corresponding lunar record). The LHB comets that delivered the iridium we see at Isua will at the same time have delivered the equivalent of a km deep ocean, and we explain why one should expect a cometary ocean to be...

  12. Did the Hilda collisional family form during the late heavy bombardment?

    CERN Document Server

    Brož, M; Morbidelli, A; Nesvorný, D; Bottke, W F; 10.1111/j.1365-2966.2011.18587.x

    2011-01-01

    We model the long-term evolution of the Hilda collisional family located in the 3/2 mean-motion resonance with Jupiter. Its eccentricity distribution evolves mostly due to the Yarkovsky/YORP effect and assuming that: (i) impact disruption was isotropic, and (ii) albedo distribution of small asteroids is the same as for large ones, we can estimate the age of the Hilda family to be $4_{-1}^{+0}\\,{\\rm Gyr}$. We also calculate collisional activity in the J3/2 region. Our results indicate that current collisional rates are very low for a 200\\,km parent body such that the number of expected events over Gyrs is much smaller than one. The large age and the low probability of the collisional disruption lead us to the conclusion that the Hilda family might have been created during the Late Heavy Bombardment when the collisions were much more frequent. The Hilda family may thus serve as a test of orbital behavior of planets during the LHB. We tested the influence of the giant-planet migration on the distribution of the ...

  13. Calculation of the enrichment of the giant planet envelopes during the "late heavy bombardment"

    CERN Document Server

    Matter, Alexis; Morbidelli, Alessandro

    2010-01-01

    The giant planets of our solar system possess envelopes consisting mainly of hydrogen and helium but are also significantly enriched in heavier elements relatively to our Sun. In order to better constrain how these heavy elements have been delivered, we quantify the amount accreted during the so-called "late heavy bombardment", at a time when planets were fully formed and planetesimals could not sink deep into the planets. On the basis of the "Nice model", we obtain accreted masses (in terrestrial units) equal to $0.15\\pm0.04 \\rm\\,M_\\oplus$ for Jupiter, and $0.08 \\pm 0.01 \\rm\\,M_\\oplus$ for Saturn. For the two other giant planets, the results are found to depend mostly on whether they switched position during the instability phase. For Uranus, the accreted mass is $0.051 \\pm 0.003 \\rm\\,M_\\oplus$ with an inversion and $0.030 \\pm 0.001 \\rm\\,M_\\oplus$ without an inversion. Neptune accretes $0.048 \\pm 0.015 \\rm\\,M_\\oplus$ in models in which it is initially closer to the Sun than Uranus, and $0.066 \\pm 0.006 \\rm\\,...

  14. Excavation and Melting of the Hadean Continental Crust by Late Heavy Bombardment

    CERN Document Server

    Shibaike, Yuhito; Ida, Shigeru

    2015-01-01

    No Hadean rocks have ever been found on Earth's surface except for zircons---evidence of continental crust, suggesting that Hadean continental crust existed but later disappeared. One hypothesis for the disappearance of the continental crust is excavation/melting by the Late Heavy Bombardment (LHB), a concentration of impacts in the last phase of the Hadean eon. In this paper, we calculate the effects of LHB on Hadean continental crust in order to investigate this hypothesis. Approximating the size-frequency distribution of the impacts by a power-law scaling with an exponent {\\alpha} as a parameter, we have derived semi-analytical expressions for the effects of LHB impacts. We calculated the total excavation/melting volume and area affected by the LHB from two constraints of LHB on the moon, the size of the largest basin during LHB, and the density of craters larger than 20 km. We also investigated the effects of the value of {\\alpha}. Our results show that LHB does not excavate/melt all of Hadean continental...

  15. Genetic transformation of Metroxylon sagu (Rottb.) cultures via Agrobacterium-mediated and particle bombardment.

    Science.gov (United States)

    Ibrahim, Evra Raunie; Hossain, Md Anowar; Roslan, Hairul Azman

    2014-01-01

    Sago palm (Metroxylon sagu) is a perennial plant native to Southeast Asia and exploited mainly for the starch content in its trunk. Genetic improvement of sago palm is extremely slow when compared to other annual starch crops. Urgent attention is needed to improve the sago palm planting material and can be achieved through nonconventional methods. We have previously developed a tissue culture method for sago palm, which is used to provide the planting materials and to develop a genetic transformation procedure. Here, we report the genetic transformation of sago embryonic callus derived from suspension culture using Agrobacterium tumefaciens and gene gun systems. The transformed embryoids cells were selected against Basta (concentration 10 to 30 mg/L). Evidence of foreign genes integration and function of the bar and gus genes were verified via gene specific PCR amplification, gus staining, and dot blot analysis. This study showed that the embryogenic callus was the most suitable material for transformation as compared to the fine callus, embryoid stage, and initiated shoots. The gene gun transformation showed higher transformation efficiency than the ones transformed using Agrobacterium when targets were bombarded once or twice using 280 psi of helium pressure at 6 to 8 cm distance.

  16. Genetic Transformation of Metroxylon sagu (Rottb. Cultures via Agrobacterium-Mediated and Particle Bombardment

    Directory of Open Access Journals (Sweden)

    Evra Raunie Ibrahim

    2014-01-01

    Full Text Available Sago palm (Metroxylon sagu is a perennial plant native to Southeast Asia and exploited mainly for the starch content in its trunk. Genetic improvement of sago palm is extremely slow when compared to other annual starch crops. Urgent attention is needed to improve the sago palm planting material and can be achieved through nonconventional methods. We have previously developed a tissue culture method for sago palm, which is used to provide the planting materials and to develop a genetic transformation procedure. Here, we report the genetic transformation of sago embryonic callus derived from suspension culture using Agrobacterium tumefaciens and gene gun systems. The transformed embryoids cells were selected against Basta (concentration 10 to 30 mg/L. Evidence of foreign genes integration and function of the bar and gus genes were verified via gene specific PCR amplification, gus staining, and dot blot analysis. This study showed that the embryogenic callus was the most suitable material for transformation as compared to the fine callus, embryoid stage, and initiated shoots. The gene gun transformation showed higher transformation efficiency than the ones transformed using Agrobacterium when targets were bombarded once or twice using 280 psi of helium pressure at 6 to 8 cm distance.

  17. Gene gun bombardment-mediated expression and translocation of EGFP-tagged GLUT4 in skeletal muscle fibres in vivo

    DEFF Research Database (Denmark)

    Lauritzen, Hans P M M; Reynet, Christine; Schjerling, Peter

    2002-01-01

    the enhanced green fluorescent protein (EGFP) labelling technique with physical transfection methods in vivo: intramuscular plasmid injection or gene gun bombardment. During optimisation experiments with plasmid coding for the EGFP reporter alone EGFP-positive muscle fibres were counted after collagenase...... treatment of in vivo transfected flexor digitorum brevis (FDB) muscles. In contrast to gene gun bombardment, intramuscular injection produced EGFP expression in only a few fibres. Regardless of the transfection technique, EGFP expression was higher in muscles from 2-week-old rats than in those from 6-week......-old rats and peaked around 1 week after transfection. The gene gun was used subsequently with a plasmid coding for EGFP linked to the C-terminus of GLUT4 (GLUT4-EGFP). Rats were anaesthetised 5 days after transfection and insulin given i.v. with or without accompanying electrical hindleg muscle stimulation...

  18. FISH analysis of the integra-tion patterns in transgenicrice co-transformed by micro-projectile bombardment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using multi-color fluorescence in situ hybridization (FISH), we localized transferred barnase-ps1 and pHctinG DNA sequences onto chromosomes of two transgenic rice plants, named Q12 and Q13, both of which were produced by micro-projectile bombardment. In both Q12 and Q13, each detected cell showed 2-3 signal spots on their chromosomes respectively. The signals of both barnase-ps1 and pHctinG were mostly detected in the adjacent chromosomal sites in which their signals were overlapped and could be recognized by the signal color on the metaphase chromosomes. Fiber FISH further demonstrated that the multiple copies in each of the two DNA sequences distributed adjacently on the DNA fiber in Q13. Combined with the results of Southern hybridization, the possible integration patterns in transgenic rice co-transformed by micro-projectile bombardment have been discussed.

  19. Emission properties and back-bombardment for CeB{sub 6} compared to LaB{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Bakr, Mahmoud, E-mail: m-a-bakr@iae.kyoto-u.ac.jp [Physics Department, Faculty of Science, Assiut University, Assiut, 71516 (Egypt); Kawai, M. [LNS, Graduate School of Science, Tohoku University, Sendai 982-0826 (Japan); Kii, T.; Zen, H.; Masuda, K.; Ohgaki, H. [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2015-02-14

    The emission properties of CeB{sub 6} compared to LaB{sub 6} thermionic cathodes have been measured using an electrostatic DC gun. Obtaining knowledge of the emission properties is the first step in understanding the back-bombardment effect that limits wide usage of thermionic radio-frequency electron guns. The effect of back-bombardment electrons on CeB{sub 6} compared to LaB{sub 6} was studied using a numerical simulation model. The results show that for 6 μs pulse duration with input radio-frequency power of 8 MW, CeB{sub 6} should experience 14% lower temperature increase and 21% lower current density rise compared to LaB{sub 6}. We conclude that CeB{sub 6} has the potential to become the future replacement for LaB{sub 6} thermionic cathodes in radio-frequency electron guns.

  20. Genetic transformation of Platymonas (Tetraselmis)subcordiformis (Prasinophyceae, Chlorophyta) using particle bombardment and glass-bead agitation

    Institute of Scientific and Technical Information of China (English)

    CUI Yulin; JIANG Peng; WANG Jinfeng; LI Fuchao; CHEN Yingjie; ZHENG Guoting; QIN Song

    2012-01-01

    Platyronas (Tetraselmis) subcordiforris is a unicellular marine green alga.It was found to be very sensitive to the herbicide Basta through a sensitivity test indicating it could be employed as a selective agent.The bar gene is a practicable and selectable marker gene.The vector containing the expression cassette of the bar gene was transferred to P.subcordiformis by both particle bombardment and glass-bead agitation and transformants were then selected using Basta.Finally,Southern blotting analysis indicated that the bar gene had been successfully integrated into the nuclear genome of P.subcordiformis using both of the transgenic techniques,with the transformation efficiency of the glass-bead method being slightly higher than that of particle bombardment.This is the first report on stable transformation ofP.subcordiformis,and will improve fundamental research and enlarge application of this alga.

  1. Formation of nanocrystalline microstructure in arc ion plated CrN films

    Institute of Scientific and Technical Information of China (English)

    Qi-min WANG; Se-Hun KWON; Kwang-Ho KIM

    2011-01-01

    Applying negative bias voltages caused significant microstructure changes in arc ion plated CrN films. Nanocrystalline microstructures were obtained by adjusting the negative bias voltage. Structural characterizations of the films were carried out using X-ray diffractometry (XRD) and high-resolution transmission electron microscopy (HR-TEM). The results indicated that increasing ion bombardment by applying negative bias voltages resulted in the formation of defects in the CrN films, inducing microstructure evolution from micro-columnar to nanocrystalline. The microhardness and residual stresses of the films were also affected. Based on the experimental results, the evolution mechanisms of the film microstructure and properties were discussed by considering ion bombardment eftects.

  2. Deposition of silicon oxynitride films by low energy ion beam assisted nitridation at room temperature

    Science.gov (United States)

    Youroukov, S.; Kitova, S.; Danev, G.

    2008-05-01

    The possibility is studied of growing thin silicon oxynitride films by e-gun evaporation of SiO and SiO2 together with concurrent bombardment with low energy N2+ ions from a cyclotron resonance (ECR) source at room temperature of substrates. The degree of nitridation and oxidation of the films is investigated by means of X-ray spectroscopy. The optical characteristics of the films, their environmental stability and adhesion to different substrates are examined. The results obtained show than the films deposited are transparent. It is found that in the case of SiO evaporation with concurrent N2+ ion bombardment, reactive implantation of nitrogen within the films takes place at room temperature of the substrate with the formation of a new silicon oxynitride compound even at low ion energy (150-200 eV).

  3. Photon counting imaging with an electron-bombarded CCD: Towards a parallel-processing photoelectronic time-to-amplitude converter

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M.; Jiggins, Stephen; Sergent, Nicolas; Zanda, Gianmarco; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom)

    2014-12-15

    We have used an electron-bombarded CCD for optical photon counting imaging. The photon event pulse height distribution was found to be linearly dependent on the gain voltage. We propose on this basis that a gain voltage sweep during exposure in an electron-bombarded sensor would allow photon arrival time determination with sub-frame exposure time resolution. This effectively uses an electron-bombarded sensor as a parallel-processing photoelectronic time-to-amplitude converter, or a two-dimensional photon counting streak camera. Several applications that require timing of photon arrival, including Fluorescence Lifetime Imaging Microscopy, may benefit from such an approach. A simulation of a voltage sweep performed with experimental data collected with different acceleration voltages validates the principle of this approach. Moreover, photon event centroiding was performed and a hybrid 50% Gaussian/Centre of Gravity + 50% Hyperbolic cosine centroiding algorithm was found to yield the lowest fixed pattern noise. Finally, the camera was mounted on a fluorescence microscope to image F-actin filaments stained with the fluorescent dye Alexa 488 in fixed cells.

  4. Structure determination of adipokinetic hormones using fast atom bombardment tandem mass spectrometry; An unknown adipokinetic hormone (AKH-III) from Locusta migratoria

    Energy Technology Data Exchange (ETDEWEB)

    Heerma, W.; Versluis, C.; Lankhof, H. (Utrecht University (Netherlands). Faculty of Chemistry, Department of Analytical Molecular Spectrometry); Oudejans, R.C.H.M.; Kooiman, F.P.; Beenakkers, A.M.T. (Utrecht University (Netherlands). Department of Experimental Zoology)

    1991-08-01

    Fast atom bombardment mass spectrometry combined with various tandem mass spectrometric techniques and accurate mass measurement were used to elucidate the structure of an unknown biologically active peptide isolated from Locusa migratoria. (author). 23 refs.; 6 figs.; 2 schemes.

  5. Ion-assisted MBE for misfit-dislocation templates serving ordered growth of SiGe islands

    Energy Technology Data Exchange (ETDEWEB)

    Lyutovich, K. [Universitaet Stuttgart, Institut fuer Halbleitertechnik, Pfaffenwaldring 47, D-70569 Stuttgart (Germany)], E-mail: lyutovich@iht.uni-stuttgart.de; Oehme, M.; Werner, J.; Bahouchi, B.; Kasper, E. [Universitaet Stuttgart, Institut fuer Halbleitertechnik, Pfaffenwaldring 47, D-70569 Stuttgart (Germany); Hofer, C.; Teichert, C. [Institute of Physics, Montanuniversitaet Leoben, Franz Josef Str. 18, A-8700 Leoben (Austria)

    2008-11-03

    In this work, Si{sup +} ions generated by the electron-beam evaporator are employed to influence strain and morphology of MBE-grown SiGe layers on Si (100) substrates. Strain relaxation of SiGe layers and modified surface morphology are attained by ion bombardment at reduced growth temperature. A study on the influence of ion energy (0-1000 eV) and density on both degree of relaxation and surface morphology is performed. Regular misfit-dislocation networks and a specific surface morphology are observed when the in situ ion bombardment at reduced temperatures leads to a degree of relaxation around 25%. This surface morphology shows uniform shallow pyramids ordered in <110> directions which provide a template favourable for nanomagnets and other opto- and nanoelectronic applications.

  6. Influence of low energy ion implantation on mechanical properties of magnetron sputtered metastable (Cr,Al)N thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ulrich, S.; Holleck, H.; Ye, J.; Leiste, H.; Loos, R.; Stueber, M.; Pesch, P.; Sattel, S

    2003-08-01

    Metastable, nanocrystalline, ternary chromium aluminum nitride thin films have been deposited by reactive unbalanced magnetron sputtering of a chromium aluminum nitride target in a pure nitrogen atmosphere. The film constitution has been examined by X-ray microanalysis, X-ray reflectivity, X-ray diffraction, transmission electron microscopy and high-resolution electron microscopy. The mechanical properties such as Vickers hardness, elastic modulus and internal stress have been determined as a function of ion energy of bombarding particles during film growth. It was possible to show that the dependence of these properties on ion energy can be described by two physical mechanisms, both subsurface nitrogen ion implantation and nitrogen ion bombardment induced relaxation processes, whereas chemical composition is not affected in the case of our reactive deposition conditions.

  7. Self-consistent versus experimental densities in the ion-ion potential derived using the energy density formalism

    Energy Technology Data Exchange (ETDEWEB)

    Guirao, A.; Vinas, X. (Dept. de Estructura y Constituyentes de la Materia, Univ. Barcelona (Spain)); Diaz, J. (Dept. de Fisica Atomica Molecular y Nuclear, Burjassot (Spain) IFIC, Burjassot (Spain))

    1992-06-01

    We have used the energy density formalism together with Skyrme forces to build up the real part of the ion-ion potential. We have analysed the elastic scattering data for the {sup 40}Ca+{sup 40}Ca reaction at several bombarding energies including a phenomenological imaginary part. The results obtained using as input the nuclear density derived from electron scattering are compared with those from theoretical semiclassical calculations of different degree of complexity. Finally, we study the role of some properties of the nuclear interactions on some magnitudes that can be compared with the experimental ones. (orig.).

  8. Study on neutron radiation field of carbon ions therapy

    CERN Document Server

    Xu, Jun-Kui; Li, Wu-Yuan; Yan, Wei-Wei; Chen, Xi-Meng; Mao, Wang; Pang, Cheng-Guo

    2015-01-01

    Carbon ions offer significant advantages for deep-seated local tumors therapy due to their physical and biological properties. Secondary particles, especially neutrons caused by heavy ion reactions should be carefully considered in treatment process and radiation protection. For radiation protection purposes, the FLUKA Code was used in order to evaluate the radiation field at deep tumor therapy room of HIRFL in this paper. The neutron energy spectra, neutron dose and energy deposition of carbon ion and neutron in tissue-like media was studied for bombardment of solid water target by 430MeV/u C ions. It is found that the calculated neutron dose have a good agreement with the experimental date, and the secondary neutron dose may not exceed one in a thousand of the carbon ions dose at Bragg peak area in tissue-like media.

  9. Search for petrographic and geochemical evidence for the late heavy bombardment on earth in early archean rocks from Isua, Greenland

    Science.gov (United States)

    Koeberl, Christian; Reimold, Wolf Uwe; McDonald, Iain; Rosing, Minik

    The Moon was subjected to intense post-accretionary bombardment between about 4.5 and 3.9 billion years ago, and there is evidence for a short and intense late heavy bombardment period, around 3.85 ± 0.05 Ga. If a late heavy bombardment occurred on the Moon, the Earth must have been subjected to an impact flux at least as intense. The consequences for the Earth must have been devastating. In an attempt to investigate if any record of such a late heavy bombardment period on the Earth has been preserved, we performed a petrographic and geochemical study of some of the oldest rocks on Earth, from Isua in Greenland. We attempted to identify any remnant evidence of shock metamorphism in these rocks by petrographic studies, and used geochemical methods to detect the possible presence of an extraterrestrial component in these rocks. For the shock metamorphic study, we studied zircon, a highly refractive mineral that is resistant to alteration and metamorphism. Zircon crystals from old and eroded impact structures were found earlier to contain a range of shock-induced features at the optical and electron microscope level. Many of the studied zircon grains from Isua are strongly fractured, and single planar fractures do occur, but never as part of sets; none of the crystals studied shows any evidence of optically visible shock deformation. Several samples of Isua rocks were analyzed for their chemical composition, including the platinum group element (PGE) abundances, by neutron activation analysis and ICP-MS. Three samples showed somewhat elevated Ir contents (up to 0.2 ppb) compared to the detection limit, which is similar to the present-day crustal background content (0.03 ppb), but the chondrite-normalized siderophile element abundance patterns are non-chondritic, which could be a sign of either a small extraterrestrial component (if an indigenous component is subtracted), or terrestrial (re)mobilization mechanisms. In absence of any evidence for shock metamorphism

  10. SPH Simulations of Volatiles Loss from Icy Satellites During a Late Heavy Bombardment

    Science.gov (United States)

    Movshovitz, N.; Nimmo, F.; Korycansky, D.; Asphaug, E. I.; Owen, J. M.

    2013-12-01

    The present day ice-to-silicate ratio in satellites of the outer solar system can be used to constrain dynamical models of solar system formation [1]. The reason is that a period of intense impact activity after formation of the planets, implied by some dynamical models [2,3,4], could have resulted in significant mass loss, of ice preferentially, from these satellites. The location of Jovian and Saturnian satellites inside the gravity well of these giant planets implies high impact velocities, perhaps as high as 30 km/s [5]. Combined with small satellite masses, a Late Heavy Bombardment may well lead to a significant fraction of a satellite's mass ejected. In a previous study, Nimmo and Korycansky [1] calculate, using a scaling law for vaporization of ice from craters [6], the total expected ice loss from satellites of Jupiter, Saturn, and Uranus. They find that many satellites should have lost significant fractions (>10%) of their water ice. As many of these satellites do not appear to be significantly depleted in volatiles, this raises questions about the timing or intensity of a late heavy bombardment. (See also [4]). But this conclusion depends on some key assumptions regarding the distribution of impactor sizes and velocities, and, critically, the expected mass loss during a single impact. Here we compare predictions of impact-driven mass loss using direct hydrodynamical simulations of the relevant impact events, with the scaling law originally developed for cratering by small impactors [6]. The main advantage of this approach is that we can consider impacts between comparably sized bodies, where a cratering scaling law does not strictly apply. Another advantage of a direct hydro simulation is that we can track escaping mass, rather than vapor production. This is most significant for lower velocity impacts, typical of accretion [7,8]. This method should also be less sensitive to the choice of equation of state. To resolve preferential ice loss during impacts

  11. Seduction of Finding Universality in Sputtering Yields Due to Cluster Bombardment of Solids.

    Science.gov (United States)

    Paruch, Robert J; Postawa, Zbigniew; Garrison, Barbara J

    2015-09-15

    Universal descriptions are appealing because they simplify the description of different (but similar) physical systems, allow the determination of general properties, and have practical applications. Recently, the concept of universality has been applied to the dependence of the sputtering (ejection) yield due to energetic cluster bombardment versus the energy of the incident cluster. It was observed that the spread in data points can be reduced if the yield Y and initial projectile cluster kinetic energy E are expressed in quantities scaled by the number of cluster atoms n, that is, Y/n versus E/n. The convergence of the data points is, however, not perfect, especially when the results for molecular and atomic solids are compared. In addition, the physics underlying the apparent universal dependence in not fully understood. For the study presented in this Account, we performed molecular dynamics simulations of Arn cluster bombardment of molecular (benzene, octane, and β-carotene) and atomic (Ag) solids in order to address the physical basis of the apparent universal dependence. We have demonstrated that the convergence of the data points between molecular and atomic solids can be improved if the binding energy of the solid U0 is included and the dependence is presented as Y/(E/U0) versus (E/U0)/n. As a material property, the quantity U0 is defined per the basic unit of material, which is an atom for atomic solids and a molecule for molecular solids. Analogously, the quantity Y is given in atoms and molecules, respectively. The simulations show that, for almost 3 orders of magnitude variation of (E/U0)/n, there are obvious similarities in the ejection mechanisms between the molecular and atomic solids, thus supporting the concept of universality. For large (E/U0)/n values, the mechanism of ejection is the fluid flow from a cone-shaped volume. This regime of (E/U0)/n is generally accessed experimentally by clusters with hundreds of atoms and results in the largest

  12. The Bombardment History of 4 Vesta as Told by Sample Geochronology

    Science.gov (United States)

    Cohen, B. A.

    2014-01-01

    with formation by a normal distribution of impact velocities and points instead to a unique period where high-velocity collisions were more frequent than currently observed. Until now, impact-reset ages in the HED meteorites have been be interpreted under the umbrella of the canonical lunar cataclysm where an increase in the absolute number of bombarding objects is responsible for creating larger absolute amounts of impact-affected and impact-melted rocks, statistically increasing their chances of being found on Earth and dated. However, the distribution of age among the howardite impact-melt clasts may not necessarily result from an increased number of impacts, but rather result from impacts of higher velocity. The changeover from a typical main belt velocity profile to this regime of increased velocity population at Vesta occurs contemporaneously with a similar transition at the Moon, indicating that howardite impact-melt clast ages reinforce the notion of a dynamically unusual episode of bombardment in the inner solar system beginning at around 4.0 Ga.

  13. Are Some Asteroid Families From The Time Of The Late Heavy Bombardment?

    Science.gov (United States)

    Morbidelli, Alessandro; Brasser, R.; Nesvorny, D.; Vokrouhlicky, D.; Bottke, W. F.

    2010-10-01

    The Late Heavy Bombardment (LHB) of the Moon 3.8 Gy ago was presumably a global event that affected the main belt asteroids as well. We do see indeed a spike in meteorite shock ages 3.8Gy ago (Kring and Swindle, 2008). Thus, we would expect that several asteroid families formed at that time. Our work on the evolution of the giant planets at the LHB-time implies that the asteroid orbits were affected less than previously thought (Morbidelli et al., DPS2009). Thus, while families that formed before or during the LHB would have been significantly dispersed in eccentricity (e) and inclination (i), they should still be recognizable today. From an analysis of the color distribution, Parker et al. (2008) showed that some asteroid families are much more dispersed in e and i than the "core" families identified from proper elements clustering. We propose here that at least some of these families formed during the LHB. As an example, we focus on the Eos family. Vokrouhlicky et al. (2006) showed that the confinement of this family within mean motion resonances requires an initial velocity dispersion <80m/s. Yet, using this initial dispersion, the subsequent evolution in the current solar system produces an (e,i) dispersion that is only half of that observed in the "core" family. In addition, the SDSS colors suggest that the real dispersion of the family is 2-3 times larger than the "core". So, there is definitely a problem in understanding the (e,i) dispersion of the Eos family. We show that a break-up event with a velocity dispersion <80m/s at the time of the LHB can easily result in a family with an identifiable core and a full dispersion comparable to that observed for objects matching Eos' color.

  14. An Archaean heavy bombardment from a destabilized extension of the asteroid belt.

    Science.gov (United States)

    Bottke, William F; Vokrouhlický, David; Minton, David; Nesvorný, David; Morbidelli, Alessandro; Brasser, Ramon; Simonson, Bruce; Levison, Harold F

    2012-05-03

    The barrage of comets and asteroids that produced many young lunar basins (craters over 300 kilometres in diameter) has frequently been called the Late Heavy Bombardment (LHB). Many assume the LHB ended about 3.7 to 3.8 billion years (Gyr) ago with the formation of Orientale basin. Evidence for LHB-sized blasts on Earth, however, extend into the Archaean and early Proterozoic eons, in the form of impact spherule beds: globally distributed ejecta layers created by Chicxulub-sized or larger cratering events4. At least seven spherule beds have been found that formed between 3.23 and 3.47 Gyr ago, four between 2.49 and 2.63 Gyr ago, and one between 1.7 and 2.1 Gyr ago. Here we report that the LHB lasted much longer than previously thought, with most late impactors coming from the E belt, an extended and now largely extinct portion of the asteroid belt between 1.7 and 2.1 astronomical units from Earth. This region was destabilized by late giant planet migration. E-belt survivors now make up the high-inclination Hungaria asteroids. Scaling from the observed Hungaria asteroids, we find that E-belt projectiles made about ten lunar basins between 3.7 and 4.1 Gyr ago. They also produced about 15 terrestrial basins between 2.5 and 3.7 Gyr ago, as well as around 70 and four Chicxulub-sized or larger craters on the Earth and Moon, respectively, between 1.7 and 3.7 Gyr ago. These rates reproduce impact spherule bed and lunar crater constraints.

  15. Cometary impact rates on the Moon and planets during the late heavy bombardment

    Science.gov (United States)

    Rickman, H.; Wiśniowski, T.; Gabryszewski, R.; Wajer, P.; Wójcikowski, K.; Szutowicz, S.; Valsecchi, G. B.; Morbidelli, A.

    2017-02-01

    Context. The Nice model predicts that the trans-planetary planetesimal disk made a large or even dominant contribution to the cratering in the inner solar system during the late heavy bombardment (LHB). In the presence of evidence that lunar craters and mare basins may be mainly of asteroidal origin, there is a dilemma of the missing comets that is not yet resolved. Aims: We aim to revisit the problem of cometary impact rates on the Moon and the terrestrial planets during the LHB with a flexible model, allowing us to study the influences of physical destruction of comets, the mass of the primordial disk, and the distribution of this mass over the entire size range. Methods: We performed a Monte Carlo study of the dynamics of the cometary LHB projectiles and derive the impact rates by calculating individual collision probabilities for a huge sample of projectile orbits. We used Minimum Orbit Intersection Distances (MOIDs) according to a new scheme introduced here. Different calculations were performed using different models for the physical evolution of comet nuclei and for the properties of the primordial, trans-planetary disk. Results: Based on the capture probability of Jupiter Trojans, we find a best fit radius of the largest LHB comet impacting the Moon for a low-mass primordial disk. For this disk mass, the LHB cratering of the Moon, Mercury and Mars were dominated by asteroids. However, some smaller lunar maria were likely preceded by comet impacts. The volatile delivery to the Earth and Mars by LHB comets was much less than their water inventories. Conclusions: There is no excessive cometary cratering, if the LHB was caused by a late planetary instability in the Nice Model. The Earth and Mars obtained their water very early in their histories. The Noachian water flows on Mars cannot be attributed to the arrival of LHB-related H2O or CO2.

  16. Repulsive interatomic potentials for noble gas bombardment of Cu and Ni targets

    Energy Technology Data Exchange (ETDEWEB)

    Karolewski, M.A. [Department of Chemistry, University of Brunei Darussalam, Jalan Tungku Link, Gadong BE 1410 (Brunei Darussalam)]. E-mail: mkarol@fos.ubd.edu.bn

    2006-01-15

    Interatomic potentials that are relevant for noble gas bombardment of Cu and Ni targets have been calculated in the energy region below 10 keV. Potentials are calculated for the diatomic species: NeCu, ArCu, KrCu, Cu{sub 2}, ArNi, Ni{sub 2} and NiCu. The calculations primarily employ density functional theory (with the B3LYP exchange-correlation functional). Potential curves derived from Hartree-Fock theory calculations are also discussed. Scalar relativistic effects have been included via the second-order Douglas-Kroll-Hess (DKH2) method. On the basis of a variational argument, it can be shown that the predicted potential curves represent an upper limit to the true potential curves. The potentials provide a basis for assessing corrections required to the ZBL and Moliere screened Coulombic potentials, which are typically found to be too repulsive below 1-2 keV. These corrections significantly improve the accuracy of the sputter yield predicted by molecular dynamics for Ni(1 0 0), whereas the sputter yield predicted for Cu(1 0 0) is negligibly affected. The validity of the pair potential approximation in the repulsive region of the potential is tested by direct calculation of the potentials arising from the interaction of either an Ar or Cu atom with a Cu{sub 3} cluster. The pairwise approximation represents the Ar-Cu{sub 3} potential energy function with an error <3 eV at all Ar-Cu{sub 3} separations. For Cu-Cu{sub 3}, the pairwise approximation underestimates the potential by ca. 10 eV when the interstitial atom is located near the centre of the cluster.

  17. High temperature annealing studies of strontium ion implanted glassy carbon

    Energy Technology Data Exchange (ETDEWEB)

    Odutemowo, O.S., E-mail: u12052613@tuks.co.za [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Malherbe, J.B.; Prinsloo, L.; Langa, D.F. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Wendler, E. [Institut für Festkörperphysik, Friedrich-Schiller University, Jena (Germany)

    2016-03-15

    Glassy carbon samples were implanted with 200 keV strontium ions to a fluence of 2 × 10{sup 16} ions/cm{sup 2} at room temperature. Analysis with Raman spectroscopy showed that ion bombardment amorphises the glassy carbon structure. Partial recovery of the glassy carbon structure was achieved after the implanted sample was vacuum annealed at 900 °C for 1 h. Annealing the strontium ion bombarded sample at 2000 °C for 5 h resulted in recovery of the glassy carbon substrate with the intensity of the D peak becoming lower than that of the pristine glassy carbon. Rutherford backscattering spectroscopy (RBS) showed that the implanted strontium diffused towards the surface of the glassy carbon after annealing the sample at 900 °C. This diffusion was also accompanied by loss of the implanted strontium. Comparison between the as-implanted and 900 °C depth profiles showed that less than 30% of the strontium was retained in the glassy carbon after heat treatment at 900 °C. The RBS profile after annealing at 2000 °C indicated that no strontium ions were retained after heat treatment at this temperature.

  18. High temperature annealing studies of strontium ion implanted glassy carbon

    Science.gov (United States)

    Odutemowo, O. S.; Malherbe, J. B.; Prinsloo, L.; Langa, D. F.; Wendler, E.

    2016-03-01

    Glassy carbon samples were implanted with 200 keV strontium ions to a fluence of 2 × 1016 ions/cm2 at room temperature. Analysis with Raman spectroscopy showed that ion bombardment amorphises the glassy carbon structure. Partial recovery of the glassy carbon structure was achieved after the implanted sample was vacuum annealed at 900 °C for 1 h. Annealing the strontium ion bombarded sample at 2000 °C for 5 h resulted in recovery of the glassy carbon substrate with the intensity of the D peak becoming lower than that of the pristine glassy carbon. Rutherford backscattering spectroscopy (RBS) showed that the implanted strontium diffused towards the surface of the glassy carbon after annealing the sample at 900 °C. This diffusion was also accompanied by loss of the implanted strontium. Comparison between the as-implanted and 900 °C depth profiles showed that less than 30% of the strontium was retained in the glassy carbon after heat treatment at 900 °C. The RBS profile after annealing at 2000 °C indicated that no strontium ions were retained after heat treatment at this temperature.

  19. Scanning-electron-microscopy observations and mechanical characteristics of ion-beam-sputtered surgical implant alloys

    Science.gov (United States)

    Weigand, A. J.; Meyer, M. L.; Ling, J. S.

    1977-01-01

    An electron bombardment ion thruster was used as an ion source to sputter the surfaces of orthopedic prosthetic metals. Scanning electron microscopy photomicrographs were made of each ion beam textured surface. The effect of ion texturing an implant surface on its bond to bone cement was investigated. A Co-Cr-W alloy and surgical stainless steel were used as representative hard tissue implant materials to determine effects of ion texturing on bulk mechanical properties. Work was done to determine the effect of substrate temperature on the development of an ion textured surface microstructure. Results indicate that the ultimate strength of the bulk materials is unchanged by ion texturing and that the microstructure will develop more rapidly if the substrate is heated prior to ion texturing.

  20. Silkworm eggs: An ideal model for studying the biological effects of low energy Ar + ion interaction in animals

    Science.gov (United States)

    Ling, Lin; Liu, Xuelan; Xu, Jiaping; You, Zhengying; Zhou, Jingbo

    2011-09-01

    The object of the current work was to study low energy Ar + ion beam interactions with silkworm eggs and thus provide further understanding of the mechanisms involved in ion bombardment-induced direct gene transfer into silkworm eggs. In this paper, using low-energy Ar + ion beam bombardment combined with piggyBac transposon, we developed a novel method to induce gene transfer in silkworm. Using bombardment conditions optimized for egg-incubation (25 keV with ion fluences of 800 × 2.6 × 10 15 ions/cm 2 in dry state under vacuum), vector pBac{3 × P3-EGFPaf} and helper plasmid pHA3pig were successfully transferred into the silkworm eggs. Our results obtained from by PCR assay and genomic Southern blotting analysis of the G1 generations provide evidence that low-energy ion beam can generate some craters that play a role in acting as pathways of exogenous DNA molecules into silkworm eggs.

  1. Ion flux and ion distribution function measurements in synchronously pulsed inductively coupled plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Brihoum, Melisa; Cunge, Gilles; Darnon, Maxime; Joubert, Olivier [Laboratoire des Technologies de la Microelectronique CNRS, Grenoble Cedex 9, Isere 38054 (France); Gahan, David [Impedans Ltd., Dublin 17 (Ireland); Braithwaite, Nicholas St. J. [Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2013-03-15

    Changes in the ion flux and the time-averaged ion distribution functions are reported for pulsed, inductively coupled RF plasmas (ICPs) operated over a range of duty cycles. For helium and argon plasmas, the ion flux increases rapidly after the start of the RF pulse and after about 50 {mu}s reaches the same steady state value as that in continuous ICPs. Therefore, when the plasma is pulsed at 1 kHz, the ion flux during the pulse has a value that is almost independent of the duty cycle. By contrast, in molecular electronegative chlorine/chlorosilane plasmas, the ion flux during the pulse reaches a steady state value that depends strongly on the duty cycle. This is because both the plasma chemistry and the electronegativity depend on the duty cycle. As a result, the ion flux is 15 times smaller in a pulsed 10% duty cycle plasma than in the continuous wave (CW) plasma. The consequence is that for a given synchronous RF biasing of a wafer-chuck, the ion energy is much higher in the pulsed plasma than it is in the CW plasma of chlorine/chlorosilane. Under these conditions, the wafer is bombarded by a low flux of very energetic ions, very much as it would in a low density, capacitively coupled plasma. Therefore, one can extend the operating range of ICPs through synchronous pulsing of the inductive excitation and capacitive chuck-bias, offering new means by which to control plasma etching.

  2. Modification of graphene by ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Bukowska, Hanna; Akcoeltekin, Sevilay; El Kharrazi, Mourad; Schleberger, Marika [Universitaet Duisburg-Essen, Fakultaet fuer Physik, Duisburg (Germany); Osmani, Orkhan [Universitaet Duisburg-Essen, Fakultaet fuer Physik, Duisburg (Germany); Technische Universitaet Kaiserslautern, Fachbereich Physik, Gottlieb-Daimler-Strasse, Gebaeude 47, 67663 Kaiserslautern (Germany)

    2010-07-01

    Ion irradiation can be used to modify surfaces on the nanometer scale. We investigate graphene on different insulator (SrTiO{sub 3}, TiO{sub 2}, and Al{sub 2}O{sub 3}) and semiconductor (SiO{sub 2}) substrates. The bombardment of those target surfaces with swift heavy ions under grazing angle of incidence creates chains of nanodots on the substrate and folds graphene to typical origami-like structures. The shape of the folded graphene seems to depend on the length of the tracks. The length can be controlled by the angle of incidence. From the analysis of atomic force microscopy measurements, we classify the different types of modifications, with the aim to determine the relationship between chain length and origami shape. Further more we want to develop a theoretical understanding of the physical processes leading to the folding.

  3. Optical Faraday Cup for Heavy Ion Beams

    Energy Technology Data Exchange (ETDEWEB)

    Bieniosek, Frank; Bieniosek, F.M.; Eylon, S.; Roy, P.K.; Yu, S.S.

    2007-06-25

    We have been using alumina scintillators for imaging beams in heavy-ion beam fusion experiments in 2 to 4 transverse dimensions [1]. The scintillator has a limited lifetime under bombardment by the heavy ion beams. As a possible replacement for the scintillator, we are studying the technique of imaging the beam on a gas cloud. A gas cloud for imaging the beam may be created on a solid hole plate placed in the path of the beam, or by a localized gas jet. It is possible to image the beam using certain fast-quenching optical lines that closely follow beam current density and are independent of gas density. We describe this technique and show preliminary experimental data. This approach has promise to be a new fast beam current diagnostic on a nanosecond time scale.

  4. Fast atom bombardment mass spectral analysis of three new oxidative products of primaquine

    Science.gov (United States)

    Sinha, Sukesh N.; Dua, V. K.

    2004-03-01

    FAB mass spectrum of 5,5-di-[6-methoxy-8-(4'-amino-1'butyl amino)] quinoline (PI) was recorded in three different concentrations to establish the structure of new oxidative products of primaquine and also the effect of matrix on percentage relative abundance of molecular as well as fragment ions which were demonstrated first time. At three concentrations, three different behaviors of matrix, molecular and fragment ions were observed. At higher concentration (>1 nM) molecular ion behaved as a base peak, but due to side reaction with matrix certain extra peak were also obtained. Thus, the higher concentration was interesting to show the side reaction of analyte with m-nitro-benzyl alcohol (NBA) but not for molecular weight determination. At the lowest concentration (NBA as a matrix was recorded in between 0.6 and 1 nM concentrations for the structural elucidation of new compounds. Molecular ions and fragment ions of 5,5-di-[6-methoxy-8-(4'-amino-1' butyl amino)] quinoline (PI), 6-methoxy-5,8-di-[4'amino-1'-methyl butyl amino] quinoline (PII), and 5,5-di-[7-hydroxy-6-methoxy-8(4'-amino-1'-methyl butyl amino)] quinoline (PIII) were identified. The fragment ions were obtained due to ring cleavages, Retero-Diels-Alder reaction (RDA), loss of side chain, proton transfer and substituted groups of the ring. On the basis of the fragmentation schemes and molecular ion peaks the structure of three new compounds PI, PII and PIII were proposed. In vitro studies showed that the compounds PI and PII had four times more gametocytocidal activity than primaquine but the compound 6-methoxy-5,8-di-[4'-amino-1'-methyl butyl amino] quinoline (PII) was found to have good gametocytocidal activity against Plasmodium yoelli infected mice at 10 mg kg-1 dose in vivo. Therefore, the spectra reported might serve as reference for the development of new molecules for the radical cure of relapsing malaria.

  5. The Impact Rate on Solar System Satellites During the Late Heavy Bombardment

    Science.gov (United States)

    Dones, Henry C. Luke; Levison, H. F.

    2012-10-01

    Nimmo and Korycansky (2012; henceforth NK12) found that if the outer Solar System underwent a Late Heavy Bombardment (LHB) in the Nice model, the mass striking the icy satellites at speeds up to tens of km/s would have vaporized so much ice that moons such as Mimas, Enceladus, and Miranda would have been devolatilized. NK12's possible explanations of this apparent discrepancy with observations include (1) the mass influx was a factor of 10 less than that in the Nice model; (2) the mass distribution of the impactors was top-heavy, so that luck might have saved some of the moons from suffering large, vapor-removing impacts; or (3) the inner moons formed after the LHB. NK12 calculated the mass influx onto the satellites from the lunar impact rate estimated by Gomes et al. (2005) and scaling factors calculated by Zahnle et al. (1998, 2003; also see Barr and Canup 2010). Production of vapor in hypervelocity impacts was calculated from Kraus et al. (2011). We are calculating impact rates onto the giant planets and their moons in the context of the "Nice II" model (Levison et al. 2011). We find that NK12's assumed influx is an overestimate, by an amount we are quantifying. We will discuss implications for the origin of icy satellites. We thank the NASA Lunar Science Institute (http://lunarscience.nasa.gov/) for support. Barr, A.C., Canup, R.M., Nature Geoscience 3, 164-167 (2010). Gomes, R., Levison, H.F., Tsiganis, K., Morbidelli, A., Nature 435, 466-469 (2005). Kraus, R.G., Senft, L.E., Stewart, S.T., Icarus 214, 724-738 (2011). Levison, H.F., Morbidelli, A., Tsiganis, K., Nesvorný, D., Gomes, R., Astron. J. 142, article id. 152 (2011). Nimmo, F., Korycansky, D.G., Icarus 219, 508-510 (2012). Zahnle, K., Dones, L., Levison, H.F., Icarus 136, 202-222 (1998). Zahnle, K., Schenk, P., Levison, H.F., Dones, L., Icarus 163, 263-289 (2003).

  6. THE NEXT GENERATION VIRGO CLUSTER SURVEY. IV. NGC 4216: A BOMBARDED SPIRAL IN THE VIRGO CLUSTER

    Energy Technology Data Exchange (ETDEWEB)

    Paudel, Sanjaya; Duc, Pierre-Alain; Ferriere, Etienne [Laboratoire AIM Paris-Saclay, CNRS/INSU, Universite Paris Diderot, CEA/IRFU/SAp, F-91191 Gif-sur-Yvette Cedex (France); Cote, Patrick; Ferrarese, Laura; Gwyn, Stephen D. J.; MacArthur, Lauren A. [National Research Council of Canada, Victoria, BC V9E 2E7 (Canada); Cuillandre, Jean-Charles [Canada-France-Hawaii Telescope Corporation, Kamuela, HI 96743 (United States); Mihos, J. Christopher [Department of Astronomy, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106 (United States); Vollmer, Bernd [Observatoire Astronomique, Universite de Strasbourg and CNRS UMR 7550, 11 rue de l' Universite, F-67000 Strasbourg (France); Balogh, Michael L. [Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Carlberg, Ray G. [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada); Boissier, Samuel; Boselli, Alessandro [Aix Marseille Universite, CNRS, LAM (Laboratoire d' Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France); Durrell, Patrick R. [Department of Physics and Astronomy, Youngstown State University, One University Plaza, Youngstown, OH 44555 (United States); Emsellem, Eric; Michel-Dansac, Leo [Universite de Lyon 1, CRAL, Observatoire de Lyon, CNRS UMR 5574, 9 av. Charles Andre, F-69230 Saint-Genis Laval (France); Mei, Simona; Van Driel, Wim, E-mail: sanjaya.paudel@cea.fr [GEPI, Observatoire de Paris, CNRS, Universite Paris Diderot, 5 Place J. Janssen, F-92190 Meudon Cedex (France)

    2013-04-20

    group which already ventured toward the central regions of Virgo Cluster. In any case, compared to the other spiral galaxies in the Virgo Cluster, but also to those located in lower density environments, NGC 4216 seems to suffer an unusually heavy bombardment. Further studies will be needed to determine whether, given the surface brightness limit of our survey, about 29 mag arcsec{sup -2}, the number of observed streams around that galaxy is as predicted by cosmological simulations or conversely, whether the possible lack of similar structures in other galaxies poses a challenge to the merger-based model of galaxy mass assembly.

  7. Constraining the cometary flux through the asteroid belt during the late heavy bombardment

    Science.gov (United States)

    Brož, M.; Morbidelli, A.; Bottke, W. F.; Rozehnal, J.; Vokrouhlický, D.; Nesvorný, D.

    2013-03-01

    In the Nice model, the late heavy bombardment (LHB) is related to an orbital instability of giant planets which causes a fast dynamical dispersion of a trans-Neptunian cometary disk. We study effects produced by these hypothetical cometary projectiles on main belt asteroids. In particular, we want to check whether the observed collisional families provide a lower or an upper limit for the cometary flux during the LHB. We present an updated list of observed asteroid families as identified in the space of synthetic proper elements by the hierarchical clustering method, colour data, albedo data and dynamical considerations and we estimate their physical parameters. We selected 12 families which may be related to the LHB according to their dynamical ages. We then used collisional models and N-body orbital simulations to gain insight into the long-term dynamical evolution of synthetic LHB families over 4 Gyr. We account for the mutual collisions between comets, main belt asteroids, and family members, the physical disruptions of comets, the Yarkovsky/YORP drift in semimajor axis, chaotic diffusion in eccentricity/inclination, or possible perturbations by the giant-planet migration. Assuming a "standard" size-frequency distribution of primordial comets, we predict the number of families with parent-body sizes DPB ≥ 200 km - created during the LHB and subsequent ≃4 Gyr of collisional evolution - which seems consistent with observations. However, more than 100 asteroid families with DPB ≥ 100 km should be created at the same time which are not observed. This discrepancy can be nevertheless explained by the following processes: i) asteroid families are efficiently destroyed by comminution (via collisional cascade), ii) disruptions of comets below some critical perihelion distance (q ≲ 1.5 AU) are common. Given the freedom in the cometary-disruption law, we cannot provide stringent limits on the cometary flux, but we can conclude that the observed distribution of

  8. Energy distribution of metal and noble gas ions traversing single-crystal copper films

    Science.gov (United States)

    Isakhanov, Z. A.

    2012-09-01

    A comparative investigation of the energy distribution of ions that traversed single-crystal cooper films reveals that the energy loss of channeled and nonchanneled particles depends not only on the mass but also on the radius of bombarding ions. It is established that the energy spectra of transmitted ions are highly sensitive to a change in the composition and structure of the films. From the change in these spectra, one can estimate the degree of disordering in thin films under various applied forces.

  9. Diamond single crystal-surface modification under high- fluence ion irradiation

    Science.gov (United States)

    Anikin, V. A.; Borisov, A. M.; Kazakov, V. A.; Mashkova, E. S.; Palyanov, Yu N.; Popov, V. P.; Shmytkova, E. A.; Sigalaev, S. K.

    2016-09-01

    The modification of (111) face of synthetic diamond has been studied experimentally for high-fluence 30 keV argon bombardment. It has been found that ion irradiation leads to the electrically conductive layer formation the sheet resistance of which decreases more than 100 times while changing the temperature of the irradiated diamond from 70 to 400 oC. This effect, as well as significant changes of optical transmittance after ion irradiation are associated with ion-induced structural changes of irradiated diamond obtained by the methods of Raman spectroscopy.

  10. Destruction and Re-Accretion of Mid-Size Moons During an Outer Solar System Late Heavy Bombardment

    Science.gov (United States)

    Movshovitz, N.; Nimmo, F.; Korycansky, D. G.; Asphaug, E. I.; Owen, M.

    2014-12-01

    To explain the lunar Late Heavy Bombardment the Nice Model (Tsiganis, K., Gomes, R., Morbidelli, A., & Levison, H. 2005, Nature, 435, 459; Tsiganis, K., Gomes, R., Morbidelli, A., & Levison, H. 2005, Nature, 435, 459) invokes a period of dynamical instability, occurring long after planet formation, that destabilizes both the main asteroid belt and a remnant exterior planetesimal disk. As a side effect of explaining the lunar LHB, this model also predicts an LHB-like period in the outer Solar System. With higher collision probabilities and impact energies due to gravitational focusing by the giant planets the inner satellites of Jupiter, Saturn, and Uranus would have experienced a bombardment much more severe than the one supposedly responsible for the lunar basins. The concern is that such bombardment should have resulted in significant, even catastrophic modification of the mid-size satellites. Here we look at the problem of satellite survival during a hypothetical outer Solar System LHB. Using a Monte-Carlo approach we calculate, for 10 satellites of Saturn and Uranus, the probability of having experienced at least one catastrophic collision during an LHB. We use a scaling law for the energy required to disrupt a target in a gravity-dominated collision derived from new SPH simulations. These simulations extend the scaling law previously obtained by Benz & Asphaug (1999, Icarus, 142, 5) to larger targets. We then simulate randomized LHB impacts by drawing from appropriate size and velocity distributions, with the total delivered mass as a controlled parameter. We find that Mimas, Enceladus, Tethys, Hyperion, and Miranda experience at least one catastrophic impact in every simulation. In most simulations, Mimas, Enceladus, and Tethys experience multiple catastrophic impacts, including impacts with energies several times that required to completely disrupt the target. The implication is that these close-in, mid-size satellites could not have survived a Late Heavy

  11. Study of Neutrons in Thick Pb Target Bombarded by 0.65~1.5 GeV Protons

    Institute of Scientific and Technical Information of China (English)

    R.Brandt; P.Vater; W.Westmeier; B.A.Kulakov; M.I.Krivopustov; A.N.Sosnin

    2001-01-01

    Study of neutrons has been carried out at thick Pb target bombarded with 0.65, 1.0 and 1.5 GeV protons from the accelerator NUCLOTRON newly built in the Joint Institute for Nuclear Research (JINR), Dubna, Russia. The Pb target is 20 cm in thickness and 8 cm in diameter. Outside the Pb target, paraffin of 6 cm in thickness is used as moderator. Proton beam from the accelerator impinged on the cylindric Pb target along its axis. The above arrangement is to simulate the core structure and nuclear reaction process of an accelerator-driven subcritical nuclear reactor. CR-39 nuclear track detector strips

  12. Role of positive ions on the surface production of negative ions in a fusion plasma reactor type negative ion source—Insights from a three dimensional particle-in-cell Monte Carlo collisions model

    Energy Technology Data Exchange (ETDEWEB)

    Fubiani, G.; Boeuf, J. P. [Université de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d' Energie), 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); CNRS, LAPLACE, F-31062 Toulouse (France)

    2013-11-15

    Results from a 3D self-consistent Particle-In-Cell Monte Carlo Collisions (PIC MCC) model of a high power fusion-type negative ion source are presented for the first time. The model is used to calculate the plasma characteristics of the ITER prototype BATMAN ion source developed in Garching. Special emphasis is put on the production of negative ions on the plasma grid surface. The question of the relative roles of the impact of neutral hydrogen atoms and positive ions on the cesiated grid surface has attracted much attention recently and the 3D PIC MCC model is used to address this question. The results show that the production of negative ions by positive ion impact on the plasma grid is small with respect to the production by atomic hydrogen or deuterium bombardment (less than 10%)

  13. Formation of oxides and segregation of mobile atoms during SIMS profiling of Si with oxygen ions

    Energy Technology Data Exchange (ETDEWEB)

    Petravic, M.; Williams, J.S.; Svensson, B.G.; Conway, M. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

    1993-12-31

    An oxygen beam is commonly used in secondary ion mass spectroscopy (SIMS) analysis to enhance the ionization probability for positive secondary ions. It has been observed, however, that this technique produces in some cases a great degradation of depth resolution. The most pronounced effects have been found for impurities in silicon under oxygen bombardment at angles of incidence smaller than {approx} 30 deg from the surface normal. A new approach is described which involved broadening of SIMS profiles for some mobile atoms, such as Cu, Ni and Au, implanted into silicon. The anomalously large broadening is explained in terms of segregation at a SiO{sub 2}/Si interface formed during bombardment with oxygen at impact angles less than 30 deg. 2 refs., 1 tab., 4 figs.

  14. Crystallographic analysis of amorphization caused by ion irradiation

    CERN Document Server

    Nakagawa, S T; Ono, T; Hada, Y; Betz, G

    2003-01-01

    Ion irradiation often causes amorphization in a crystal. We have presented a new crystallographic analysis that defines a new type of order parameter, which we call pixel mapping (PM). PM can describe algebraically to what extent and how the crystallinity has changed under ion bombardment. In other words, PM describes the long-range-order (LRO) interactions, based on the crystallography. PM can be effectively used, when it is incorporated in a classical molecular dynamics (MD) calculation. In the case of B ions implanted into a Si crystal, we observed crystal to amorphous (CA) transitions under energetic ion bombardment at low temperature. The PM profiling was more effective to reveal the CA transition than other atomistic methods of analyses as radial distribution function g(r) or vacancy mapping N sub v. PM could distinguish between perfect crystalline states, transition states, and random states. Moreover, PM revealed that the lattice reaction was cooperative even in a mesoscopic volume, e.g. in a cube of ...

  15. Ion Beam Nanostructuring of HgCdTe Ternary Compound

    Science.gov (United States)

    Smirnov, Aleksey B.; Savkina, Rada K.; Udovytska, Ruslana S.; Gudymenko, Oleksandr I.; Kladko, Vasyl P.; Korchovyi, Andrii A.

    2017-05-01

    Systematic study of mercury cadmium telluride thin films subjected to the ion beam bombardment was carried out. The evolution of surface morphology of (111) Hg1 - x Cd x Te ( x 0.223) epilayers due to 100 keV B+ and Ag+ ion irradiation was studied by AFM and SEM methods. X-ray photoelectron spectroscopy and X-ray diffraction methods were used for the investigation of the chemical compound and structural properties of the surface and subsurface region. It was found that in the range of nanoscale, arrays of holes and mounds on Hg0.777Cd0.223Te (111) surface as well as the polycrystalline Hg1 - x Cd x Te cubic phase with alternative compound ( x 0.20) have been fabricated using 100 keV ion beam irradiation of the basic material. Charge transport investigation with non-stationary impedance spectroscopy method has shown that boron-implanted structures are characterized by capacity-type impedance whereas for silver-implanted structures, an inductive-type impedance (or "negative capacitance") is observed. A hybrid system, which integrates the nanostructured ternary compound (HgCdTe) with metal-oxide (Ag2O) inclusions, was fabricated by Ag+ ion bombardment. The sensitivity of such metal-oxide-semiconductor hybrid structure for sub-THz radiation was detected with NEP 4.5 × 10-8 W/Hz1/2at ν ≈ 140 GHz and 296 K without amplification.

  16. Hardening of graphite surface by ion beam amorphization

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, J.P.; Stone, D.; Nastasi, M.; Hannula, S.P.

    1986-05-01

    Ion implantation has been shown to possess potential as a practical method for improving the mechanical properties of surfaces. So far a number of tests have been performed. In these studies, metals - most often steels or other hard materials - have been used. However, the improvement of the mechanical properties at the surface is not only important for substances that already have considerable hardness, but also for materials with other unique properties. Graphite is useful in many applications. Mechanically, it is easily machined and has good dimensional stability. It has self lubricity and under certain conditions has excellent sliding properties. Chemically, it is generally impermeable, resistant to corrosion, and compatable with mating materials. It is a good conductor of both heat and electrical current. The ion implantation of graphite has been studied elsewhere but without reference to the mechanical properties of the surface. It is expected, however, that heavy ion bombardment will cause structural changes at the graphite surface resulting in a modification of the mechanical properties. In this investigation the authors focus on these properties. The main objectives have been to study how the surface mechanical properties are changed by an ion bombardment and to find the relationship between mechanical properties and microstructure.

  17. Sputtering and surface structure modification of gold thin films deposited onto silicon substrates under the impact of 20–160 keV Ar{sup +} ions

    Energy Technology Data Exchange (ETDEWEB)

    Mammeri, S., E-mail: smammeri@yahoo.fr [Centre de Recherche Nucléaire d’Alger, B.P. 399, 02 Bd. Frantz Fanon, Alger-Gare, Algiers (Algeria); Ouichaoui, S. [Université des Sciences et de la Technologie H. Boumediene (USTHB), Faculté de Physique, Laboratoire SNIRM, B.P. 32, El-Alia, 16111 Bab Ezzouar, Algiers (Algeria); Ammi, H.; Dib, A. [Centre de Recherche Nucléaire d’Alger, B.P. 399, 02 Bd. Frantz Fanon, Alger-Gare, Algiers (Algeria)

    2014-10-15

    Highlights: •Sputter yields were measured for gold thin films under keV Ar{sup +} ion bombardment. •RBS analysis was used to derive energy dependence of sputtering yield. •Surface effects under Ar{sup +} ion irradiation were studied by SEM and XRD analyses. -- Abstract: The induced sputtering and surface state modification of Au thin films bombarded by swift Ar{sup +} ions under normal incident angle have been studied over an energy range of (20–160) keV using three complementary techniques: Rutherford backscattering spectroscopy (RBS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The sputtering yields determined by RBS measurements using a 2 MeV {sup 4}He{sup +} ion beam were found to be consistent with previous data measured within the Ar{sup +} ion energy region E ⩽ 50 keV, which are thus extended to higher bombarding energies. Besides, the SEM and XRD measurements clearly point out that the irradiated Au film surfaces undergo drastic modifications with increasing the Ar{sup +} ion energy, giving rise to the formation of increasingly sized grains of preferred (1 1 1) crystalline orientations. The relevance of different sputtering yield models for describing experimental data is discussed with invoking the observed surface effects induced by the Ar{sup +} ion irradiation.

  18. Nano-indentation of ion-beam modified HfN/Si system: Identification of the amorphized inter-layer

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, R. E-mail: nowak@ohm.mec.hiroshima-u.ac.jp; Li, C.L.; Okada, T.; Yoshida, F

    1999-01-02

    The work aims to clarify the considerable softening registered for the HfN/Si system after its bombardment with energetic ions (E=1, 2.5 and 5 MeV, fluence=10{sup 14} Au{sup ++}cm{sup -2}). The mechanical properties of the virgin and ion-modified films were characterized using the depth-sensing indentation experiments performed under maximum indentation load ranging from 2 to 50 mN. The surface deformation in the vicinity of the contact with a triangular indenter was modeled by the finite element simulation of the axisymmetric-indenter penetration into the hard-film/soft-substrate system. The applied approach allowed us to attribute the observed difference in hardness of virgin and ion-treated samples to the structural changes which have been induced in the silicon substrate by bombarding ions. The calculated results led us to the conclusion that bombardment with energetic Au-ions resulted in formation of the inter-layer of amorphous silicon, right under HfN film. The present work aims to prove that the depth-sensing experiments supplemented by the finite-element calculations provide a new, powerful method of characterizing the multilayer structures.

  19. Comparative study of depth and lateral distributions of electron excitation between scanning ion and scanning electron microscopes.

    Science.gov (United States)

    Ohya, Kaoru; Ishitani, Tohru

    2003-01-01

    In order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM), the depth and lateral distributions of secondary electrons escaped from surfaces of 17 metals with atomic numbers, Z2, of 4-79 were calculated for bombardment with 30 keV Ga ions and for 10 keV electrons. For both projectiles, the excitation depth generally decreased with increasing Z2, while showing the same periodic change as the secondary-electron yield. However, an opposite trend in Z2 dependence between the Ga ion and electron bombardments was calculated with the lateral distribution of secondary electrons escaped from the surface. Except for low Z2 metals, the lateral distribution, which is much narrower for 30 keV Ga ions than for 10 keV electrons, indicates that the spatial resolution of the secondary-electron images is better for SIM than for SEM, if zero-sized probe beams are assumed. Furthermore, the present calculation reveals important effects of electron excitation by recoiled material atoms and reflected electrons on the lateral distribution, as well as the secondary-electron yield, for the Ga ion and electron bombardments, respectively.

  20. Ion-Ion Neutralization.

    Science.gov (United States)

    1980-12-31

    plasma were identified using a downstream quadrupole mass spectrometer. In these experimento it is a simple matter to establish H+(H 2 0):f as the...pressure as predicted by the Thomson t2rnary mechanism whicK hzr been suownr to be valid experimentally at hiTh rrsurs (,han and Peron, 1:EI4 hereafter t...of NO , NO2 ions in various gases and the ternary recombination coefficients of these ions in the higher pres:;ure ( Thomson ) re"ie. Equation (5) cr>n

  1. Ion-induced stress relaxation during the growth of cubic boron nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Abendroth, B.E.

    2004-08-01

    in this thesis the deposition of cubic boron nitride films by magnetron sputtering is described. The deposition process is analyzed by Langmuir-probe measurement and energy resolved mass spectroscopy. the films are studied by stress measurement, spectroscopic ellipsometry, infrared spectroscopy, elastic recoil detection analysis, Rutherford backscattering spectroscopy, X-ray absorption near edge spectroscopy, X-ray diffraction, and transmission electron microscopy. Discussed are the stress relaxation and the microstructure and bonding characteristics together with the effects of ion bombardement. (HSI)

  2. Sputtering of solid hydrogenic targets by keV hydrogen ions

    DEFF Research Database (Denmark)

    Stenum, B.; Schou, Jørgen; Ellegaard, O.;

    1991-01-01

    The first sputtering measurements of the most volatile solid hydrogenic targets are reported. Bombardment of these targets by hydrogen and deuterium ions leads to erosion predominantly via electronic transitions. The magnitude of the yield depends strongly on the particular isotope. No existing...... theory for this electronic sputtering can explain the large yields that range from about 100 D2/H for solid deuterium up to 800 H-2/H for solid hydrogen....

  3. Sputtering of the Europa surface by thermal ions from the torus and pickup ions in a diverted flow

    Science.gov (United States)

    Dols, Vincent J.; Cassidy, Timothy A.; Bagenal, Fran; Crary, Frank; Delamere, Peter A.

    2016-10-01

    Europa's atmosphere is very tenuous and is mainly composed of O2. It is thought to be produced by ion bombardment of its icy surface. Several ion populations may contribute to this sputtering:1) The thermal plasma of the torus (~ 1keV including ram velocity), which may be partially diverted around the moon by the ionospheric currents2) The energetic sulfur and hydrogen ions (~10 keV-MeV), which diffuse inward toward Europa's orbit3) and possibly the newly ionized O2 molecules that are picked up by the torus flow and hit the surface.The relative contribution of each sputtering ion population has been debated for more than three decades with estimated O2 sputtering rates varying by ~2 order of magnitude. Modelers have historically focused on a single piece of the puzzle: plasma modelers assume a static atmosphere and tend not to check that their sources and losses are consistent with their prescribed atmosphere; while atmospheric modelers neglect the electro-dynamic interaction that diverts torus plasma around the moon, and limits the ion flux to the surface.In this work, we present a first step to compute self-consistently the atmospheric production by the bombardment of the thermal plasma and pickup O2+ ions.1) We calculate the plasma flow around Europa with a MHD model2) We use this flow in a multi-species physical chemistry model of the plasma-atmosphere interaction to compute the ion fluxes into Europa's surface.3) We compute the production rate of O2 resulting from the ice sputtering by thermal and pickup ions and compare the resulting atmospheric source rate to previously published results.

  4. On singlet metastable states, ion flux and ion energy in single and dual frequency capacitively coupled oxygen discharges

    Science.gov (United States)

    Hannesdottir, H.; Gudmundsson, J. T.

    2017-05-01

    We apply particle-in-cell simulations with Monte Carlo collisions to study the influence of the singlet metastable states on the ion energy distribution in single and dual frequency capacitively coupled oxygen discharges. For this purpose, the one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 is used, in which the discharge model includes the following nine species: electrons, the neutrals O(3P) and O{{}2}≤ft({{\\text{X}}3} Σ g-\\right. ), the negative ions O-, the positive ions O+ and O2+ , and the metastables O(1D), O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right) and O2(b{{}1} Σ g+ ). Earlier, we have explored the effects of adding the species O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right. ) and O2(b{{}1} Σ g+ ), and an energy-dependent secondary electron emission yield for oxygen ions and neutrals, to the discharge model. We found that including the two molecular singlet metastable states decreases the ohmic heating and the effective electron temperature in the bulk region (the electronegative core). Here we explore how these metastable states influence dual frequency discharges consisting of a fundamental frequency and the lowest even harmonics. Including or excluding the detachment reactions of the metastables O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right. ) and O2(b{{}1} Σ g+ ) can shift the peak electron temperature from the grounded to the powered electrode or vice versa, depending on the phase difference of the two applied frequencies. These metastable states can furthermore significantly influence the peak of the ion energy distribution for O2+ -ions bombarding the powered electrode, and hence the average ion energy upon bombardment of the electrode, and lower the ion flux.

  5. Particle Simulations of a Thermionic RF Gun with Gridded Triode Structure for Reduction of Back-Bombardment

    CERN Document Server

    Kusukame, K; Kii, T; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H

    2005-01-01

    Thermionic RF guns show advantageous features compared with photocathode ones such as easy operation and much higher repetition rate of micropulses, both of which are suitable for their application to high average power FELs. They however suffer from the back-bombardment effect [1], i.e., in conventional RF guns, electrons are extracted from cathode also in the latter half of accelerating phase and tend to back-stream to hit the cathode, and as a result the macropulse duration is limited down to severalμsec Against this adverse effect in thermionic RF guns, introduction of the triode structure has been proposed [2], where the accelerating phase and amplitude nearby the cathode can be controlled regardless of the phase of the first accelerating cell in the conventional RF gun. Our one-dimensional particle simulation results predict that the back-bombardment power can be reduced by 99 % only with 30-40 kW RF power fed to the grid in the present triode structure with an optimal phase difference from th...

  6. Conifer genetic engineering: Particle bombardment and Agrobacterium-mediated gene transfer and its application in future forests

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Many important advances in forest biotechnology have been made. The use of genetic transformation and the applications of transgenic trees in modern forestry is now an important field. Two basic methodologies particle bombardment and Agrobacterium-mediated transformation have been used on conifers. However, routine procedures exist for only a limited number of conifers. As a result only a few species have been successfully transformed into stable transgenic plants. The use of a particle bombardment has been more successful and transgenic plants have been produced in Picea abies, Picea glauca, Picea mariana, and Pinus radiata, although the level of production of stable transgenic plants is lower than that of Agrobacte-rium. At present, breeding programs have been directed toward improving bole shape, growth rate, wood properties, and quality, as well as toward improving root and shoot performance, pest resistance, stress tolerance, herbicide resistance, and ability to resist stresses, which will drive forestry to enter a new era of productivity and quality. This article provides a brief overview of the current state of knowledge on genetic transformation in conifers.

  7. Defect Structures in 4H-SiC Irradiated with Highly-energetic 20Ne4+ and 120Xe26+ Ions

    Institute of Scientific and Technical Information of China (English)

    ZhangChonghong; SunYoumei; T.Shibayama; LiuJie; WangZhiguang; SongYin; DuanJinglai; ZhaoZhiming; YaoCunfeng; WangYing; HouMingdong; JinYunfan

    2003-01-01

    The study of damage evolution in silicon carbide bombarded with energetic helium ions is important for the use of this material in future fusion reactors. Heavier inert gas atoms like Ne and Xe have similar behavior of diffusion and clustering with helium, and the comparison of damage accumulation behavior between energetic helium and heavier inert gas ions can reveal important aspects of underlying mechanisms. As an extension of our

  8. Effects of evolving surface morphology on yield during focused ion beam milling of carbon

    Energy Technology Data Exchange (ETDEWEB)

    Adams, D.P. [Thin Film, Vacuum and Packaging Department, Sandia National Laboratories, P.O. Box 5800, MS 0959, Albuquerque, NM 87185 (United States)]. E-mail: dpadams@sandia.gov; Mayer, T.M. [Thin Film, Vacuum and Packaging Department, Sandia National Laboratories, P.O. Box 5800, MS 0959, Albuquerque, NM 87185 (United States); Vasile, M.J. [Thin Film, Vacuum and Packaging Department, Sandia National Laboratories, P.O. Box 5800, MS 0959, Albuquerque, NM 87185 (United States); Archuleta, K. [Thin Film, Vacuum and Packaging Department, Sandia National Laboratories, P.O. Box 5800, MS 0959, Albuquerque, NM 87185 (United States)

    2006-01-15

    We investigate evolving surface morphology during focused ion beam bombardment of C and determine its effects on sputter yield over a large range of ion dose (10{sup 17}-10{sup 19} ions/cm{sup 2}) and incidence angles ({theta} = 0-80{sup o}). Carbon bombarded by 20 keV Ga{sup +} either retains a smooth sputtered surface or develops one of two rough surface morphologies (sinusoidal ripples or steps/terraces) depending on the angle of ion incidence. For conditions that lead to smooth sputter-eroded surfaces there is no change in yield with ion dose after erosion of the solid commences. However, for all conditions that lead to surface roughening we observe coarsening of morphology with increased ion dose and a concomitant decrease in yield. A decrease in yield occurs as surface ripples increase wavelength and, for large {theta}, as step/terrace morphologies evolve. The yield also decreases with dose as rippled surfaces transition to have steps and terraces at {theta} = 75{sup o}. Similar trends of decreasing yield are found for H{sub 2}O-assisted focused ion beam milling. The effects of changing surface morphology on yield are explained by the varying incidence angles exposed to the high-energy beam.

  9. Secondary ion emission from CO2-H2O ice irradiated by energetic heavy ions: Part II: Analysis-search for organic ions

    Science.gov (United States)

    Ponciano, C. R.; Farenzena, L. S.; Collado, V. M.; da Silveira, E. F.; Wien, K.

    2005-06-01

    Secondary ion mass spectrometry is used to investigate ion emission from a frozen-gas mixture of CO2 and H2O (T = 80-90 K) bombarded by MeV nitrogen ions and by 252Cf fission fragments. The aim of the experiment is to detect organic molecules, produced in the highly excited material around the nuclear track, which appear as ions in the flux of sputtered particles. Part I of the present work [L.S. Farenzena, V.M. Collado, C.R Ponciano, E.F. da Silveira, K. Wien. Int. J. Mass Spectrom. 243 (2005) 85-93] described the method and presented the time-of-flight mass spectra; a list of the CO2 specific and H2O specific reaction products was provided. In Part II, the peaks of the TOF mass spectra are analyzed. Projectile-ice direct coulomb interaction leads to the production in the track of the H+, C+, O+, O2+, CO+ and CO2+ primarily ions, which react in the highly energized nuclear track plasma mainly with CO2 and H2O or H2CO3. The positive molecular hybrid ions formed are identified as organic species like COH+, COOH+, CHn = 1-3+, Hn = 1,2COOH+ and cluster ions. Similarly, the negative primarily ions O- and OH- formed by electron capture produce negative hybrid ions such as (CO2)nOH-, the four ions (CO4Hm = 0-3)- and the corresponding cluster ions. By far, most of the molecular ions have been formed by one-step reactions; exceptions are eventually the CO4Hm- ions created by a reaction between CO3- and water molecules. An intense mass line corresponding to HCO3+ has been observed, but not the one due to formaldehyde ion. Weak signals of ionic ketene, hydrogen peroxide and carbonic acid were seen.

  10. Two-dimensional numerical research on effects of titanium target bombarded by TEMP Ⅱ accelerator

    Institute of Scientific and Technical Information of China (English)

    Wu Di; Gong Ye; Liu Jin-Yuan; Wang Xiao-Gang; Liu Yue; Ma Teng-Cai

    2006-01-01

    Two-dimensional numerical research has been carried out on the ablation effects of titanium target irradiated by intense pulsed ion beam (IPIB) generated by TEMP Ⅱ accelerator. Temporal and spatial evolution of the ablation process of the target during a pulse time has been simulated. We have come to the conclusion that the melting and evaporating process begin from the surface and the target is ablated layer by layer when the target is irradiated by the IPIB. Meanwhile, we also obtained the result that the average ablation velocity in target central region is about 10 m/s, which is far less than the ejection velocity of the plume plasma formed by irradiation. Different effects have been compared to the different ratio of the ions and different energy density of IPIB while the target is irradiated by pulsed beams.

  11. Compositional changes of lithium coatings on TZM molybdenum during plasma bombardment

    Science.gov (United States)

    Abrams, T.; Jaworski, M. A.; Kaita, R.; de Temmerman, G.; Gleeson, M. A.; Lof, A. R.; Scholten, J.; van den Berg, M. A.; van der Meiden, H. J.; Raman, P.; Ruzic, D. N.

    2012-10-01

    The Titanium-Zirconium-Molybdenum alloy TZM has previously been used as a metallic plasma-facing component in Alcator C-Mod is being considered for use in NSTX-Upgrade. The time evolution of lithium (Li) coatings on TZM are studied in Magnum-PSI, a linear plasma device capable of ion fluxes up to 10^25 m-2s-1 at electron temperatures mean free path (MFP) of Li was calculated and validations against the ADAS collisional-radiative model (CRM) will be reported. Separate measurements with a 100-1000 eV D^+ ion beam incident on Li-coated TZM were also obtained and compared with theoretical predictions of physical sputtering rates.

  12. Ion beam sputtering of Ag – Angular and energetic distributions of sputtered and scattered particles

    Energy Technology Data Exchange (ETDEWEB)

    Feder, René, E-mail: rene.feder@iom-leipzig.de; Bundesmann, Carsten; Neumann, Horst; Rauschenbach, Bernd

    2013-12-01

    Ion beam sputter deposition (IBD) provides intrinsic features which influence the properties of the growing film, because ion properties and geometrical process conditions generate different energy and spatial distribution of the sputtered and scattered particles. A vacuum deposition chamber is set up to measure the energy and spatial distribution of secondary particles produced by ion beam sputtering of different target materials under variation of geometrical parameters (incidence angle of primary ions and emission angle of secondary particles) and of primary ion beam parameters (ion species and energies). A representative set of Ag thin films is deposited arranged on a substrate holder equatorial to the Ag target in steps of 10° and characterized concerning their film thickness by profilometry to determine the angular distribution of the sputtered particles. The film thickness distributions show a tilted, cosine-like shape and a shifting of the maximum position depending on the primary particle energy and incidence angle of the primary ions. The energy distributions of sputtered and scattered ions and of sputtered neutrals are measured with an energy-selective mass spectrometer. The average energy of the sputtered ions increases with increasing emission angle and also increases with increasing incidence angle of the primary ions. In contrast, the average energy of the sputtered ions is nearly unaffected by the primary particle energy and particle species. The energy distribution of the scattered Ar ions reveals high energetic maxima which shift with increasing emission angle to higher energies. These maxima are not observed for Xe bombardment. The total energies of sputtered and scattered ions show significant differences between the two bombarding species. The maximum of the energy distribution of sputtered Ag neutrals is used to conclude on the surface binding energy of Ag (2.72 eV). All experimental data are compared with Monte Carlo simulations done with

  13. Heavy-ion reactions at the GSI Darmstadt

    Energy Technology Data Exchange (ETDEWEB)

    Metag, V. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)]|[Giessen Univ. (Germany). 2. Physikalisches Inst.

    1998-12-01

    In nucleus-nucleus collisions at bombarding energies on the order of 1 AGeV nuclear matter can be compressed to similar densities as encountered in stellar processes, i.e. to 2-3 times normal density. Experimental data providing information on the space-time evolution of these collisions are presented: the properties of hadrons in the hot and compressed nuclear medium in the high-density phase, collective flow phenomena during the expansion phase, and the hadrochemical composition of the collision system in the final stage of the reaction at freeze-out are discussed. Future directions in the heavy-ion reaction program are indicated. (orig.)

  14. Clusters distributions on charges and dimensions at ion metal sputtering

    CERN Document Server

    Matveev, V I

    2001-01-01

    The theory on the metal sputtering in form of large (with the atoms number N >= 5) neutral and charged clusters under the impact of the ion bombardment is considered. The probability of the cluster emission, consisting of the N atoms, is calculated on the basis of the Einstein model. The charge state of the cluster, consisting of the N atoms, is determined. The obtained formulae agree well with the experimental results. It is noted, that the mass-spectra of the neutral clusters slightly depend on the target temperature, whereas the mass-spectra of the single charge clusters essentially depend on the target temperature

  15. Optimum plasma grid bias for a negative hydrogen ion source operation with Cs

    Energy Technology Data Exchange (ETDEWEB)

    Bacal, Marthe, E-mail: marthe.bacal@lpp.polytechnique.fr [UPMC, LPP, Ecole Polytechnique, UMR CNRS 7648, Palaiseau (France); Sasao, Mamiko [R& D Promotion Organization, Doshisha University, Kamigyoku, Kyoto 602-8580 (Japan); Wada, Motoi [School of Science and Engineering, Doshisha University, Kyotonabe, Kyoto 610-0321 (Japan); McAdams, Roy [CCFE, Culham Science Center, Abingdon, Oxfordshire 0X14 3DB (United Kingdom)

    2016-02-15

    The functions of a biased plasma grid of a negative hydrogen (H{sup −}) ion source for both pure volume and Cs seeded operations are reexamined. Proper control of the plasma grid bias in pure volume sources yields: enhancement of the extracted negative ion current, reduction of the co-extracted electron current, flattening of the spatial distribution of plasma potential across the filter magnetic field, change in recycling from hydrogen atomic/molecular ions to atomic/molecular neutrals, and enhanced concentration of H{sup −} ions near the plasma grid. These functions are maintained in the sources seeded with Cs with additional direct emission of negative ions under positive ion and neutral hydrogen bombardment onto the plasma electrode.

  16. Electrical properties of oxygen ion-implanted InP

    Science.gov (United States)

    He, L.; Anderson, W. A.

    1992-10-01

    The effect of oxygen ion implantation on defect levels and the electrical properties of undoped InP ( n-type) and Sn-doped InP have been investigated as a function of postimplant annealing at temperatures of 300 and 400° C. The surface interruption by ion bombardment was studied by a non-invasive optical technique—photoreflectance (PR) spectroscopy. Current-voltage (I-V) characterization and deep level transient spectros-copy (DLTS) were carried out. The free carrier compensation mechanism was studied from the microstructure behavior of defect levels associated with O+ implantation. Free carriers may be trapped in both residual and ion-bombardment-induced defect sites. Rapid thermal annealing (RTA) performed at different temperatures showed that if residual traps were removed by annealing, the compensation efficiency will be enhanced. Post-implant RTA treatment showed that at the higher temperature (400°C), trapped carriers may be re-excited, resulting in a weakened compensation. Comparing the results of undoped and Sn-doped InP indicated that the carrier compensation effect is substrate doping dependent.

  17. Plasma-Based Ion Beam Sources

    Energy Technology Data Exchange (ETDEWEB)

    Loeb, H. W.

    2005-07-01

    Ion beam sources cover a broad spectrum of scientific and technical applications delivering ion currents between less than 1 mA and about 100 A at acceleration voltages between 100 V and 100 kV. The ions are mostly generated by electron collisions in a gas discharge and then extracted from the discharge plasma, focused and post-accelerated by single- or multi-aperture electrode systems. Some important applications require the neutralization of the exhausted beam either by charge exchange or by admixture of electrons. In the first part of the paper, the theory of ionization by electron impact, the energy and carrier balances in the plasma, and the extraction and focusing mechanisms will be outlined. The principles of the preferred gas discharges and of the ion beam sources based on them are discussed; i.e. of the Penning, bombardment, arc, duoplasmatron, radio frequency, and microwave types. In the second part of the paper, the special requirements of the different applications are described together with the related source hardware. One distinguishes: 1. Single-aperture ion sources producing protons, heavy ions, isotope ions, etc. for particle accelerators, ion microprobes, mass spectrometers, isotope separators, etc.; quality determinative quantities are brightness, emittance, energy width, etc. 2. Broad-beam multi-aperture injector sources for fusion machines with positive or negative deuterium ions; very high beam densities, small portions of molecular ions, flat beam profiles with small divergence angles, etc. are required. 3. Broad-beam multi-aperture ion thrusters for space propulsion operated with singly charged xenon ions; high efficiencies, reliable operation, and long lifetimes are most important. Spin-offs are applied in industry for material processing. Referring to these applications, the following sources will be described in some detail: 1. Cold cathode and filament driven sources, capillary arc and plasmatron types, microwave and ECR-sources. 2

  18. The Characteristics Of The Direct Metal Ion Beam Source And Its Applications (indium Tin Oxide)

    CERN Document Server

    Kim, D

    2001-01-01

    It is well known that thin film properties depends on its microstructures and the surface mobility is most important parameters to consider microstructures and to obtain high quality thin films. Thus, currently ion beam based deposition which can control surface mobility with kinetic energy of auxiliary gas ion investigated intensively. Recently we developed the DMIBD system which can control ion beam energy precisely under 500Ev and also ion beam flux, independently. In this work, the optimum process parameters of DMIBD such as secondary ion yields, ion/atom arrival ratios, ion energy spread, and deposition rates for various metal targets were measured as functions of Cs+ ion bombarding energy, Cs+ ion dose, and secondary ion beam energy, respectively. From the results, the secondary ion yields for C,Al,Si,Cu,Ta, and W were about 20% and the ion energy spread also less than 10% regardless of the ion beam energy. In order to investigated the effect of secondary ion beam energy on the thin film properties such...

  19. Atomic-scale thermocapillary flow in focused ion beam milling

    Energy Technology Data Exchange (ETDEWEB)

    Das, K.; Johnson, H. T.; Freund, J. B., E-mail: jbfreund@illinois.edu [Mechanical Science and Engineering and Aerospace Engineering, University of Illinois at Urbana–Champaign, 1206 West Green Street MC-244, Urbana, Illinois 61801 (United States)

    2015-05-15

    Focused ion beams provide a means of nanometer-scale manufacturing and material processing, which is used for applications such as forming nanometer-scale pores in thin films for DNA sequencing. We investigate such a configuration with Ga{sup +} bombardment of a Si thin-film target using molecular dynamics simulation. For a range of ion intensities in a realistic configuration, a recirculating melt region develops, which is seen to flow with a symmetrical pattern, counter to how it would flow were it driven by the ion momentum flux. Such flow is potentially important for the shape and composition of the formed structures. Relevant stress scales and estimated physical properties of silicon under these extreme conditions support the importance thermocapillary effects. A flow model with Marangoni forcing, based upon the temperature gradient and geometry from the atomistic simulation, indeed reproduces the flow and thus could be used to anticipate such flows and their influence in applications.

  20. Introduction of cecropin B gene into rice (Oryza sativa L.) by particle bombardment and analysis of transgenic plants

    Institute of Scientific and Technical Information of China (English)

    黄大年; 朱冰; 杨炜; 薛锐; 肖晗; 田文忠; 李良材; 戴顺洪

    1996-01-01

    An expression vector pCBl suitable for rice transformation, harboring a synthesized cecropin B gene and a selectable marker gene (bar), was constructed. It was introduced into immature embryos of two japonica varieties by particle bombardment, and several transgenic plants were obtained. The results from Basta treatment, PCR analysis, dot and Southern blot analysis of cecropin B gene in transgenic plants indicated that both bar and cecropin B gene were integrated into the genome of transformed plants. Northern blot analysis of transgenic plants showed the expression of cecropin B gene at transcriptional level. Some of transgenic plants revealed improved resistances to two types of bacterial diseases, rice bacterial blight and rice bacterial streak to different extent.

  1. Transfer and Detection of barstar Gene to Maize Inbred Line 18-599 (White) by Particle Bombardment

    Institute of Scientific and Technical Information of China (English)

    SUN Qing-quan; ZHANG Ying; RONG Ting-zhao; DONG Shu-ting; ZUO Zhen-peng

    2007-01-01

    In China, the purity of maize hybrid strain is discomforting to the development of seed industrialization. Finding a new method for reproduction of maize hybrid strain is necessary. In this study, using particle bombardment, barstar gene was transferred into maize inbred line 18-599 (White), which is an antiviral and high quality maize inbred line. By molecular detection of the anther of transgenic maize, two plants transferred with barstar gene were gained in this study, which are two restorer lines. The two plants showed normal male spike, and lively microspores. But the capacity of the two restorer lines should be studied in the future. The aim of this study is to find a new method of reproduction of maize hybrid strain using engineering restorer lines and engineering sterility lines by gene engineering technology.

  2. Production cross-sections of {sup 181-186}Re isotopes from proton bombardment of natural tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Lapi, S. [Simon Fraser University, 8888 University Drive, Burnaby BC, V5A 1S6 (Canada) and TRIUMF, Pet Group, 4004 Wesbrook Mall, Vancouver BC, V6T 2A3 (Canada)]. E-mail: slapi@sfu.ca; Mills, W.J. [Simon Fraser University, 8888 University Drive, Burnaby BC, V5A 1S6 (Canada); Wilson, J. [University of Alberta, 11560 University Avenue, Edmonton, AB, T6G 1Z2 (Canada); McQuarrie, S. [University of Alberta, 11560 University Avenue, Edmonton, AB, T6G 1Z2 (Canada); Publicover, J. [University of Victoria, 3800 Finnerty Road, Victoria, BC, V8W 5C2 (Canada); Schueller, M. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Schyler, D. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Ressler, J.J. [Simon Fraser University, 8888 University Drive, Burnaby BC, V5A 1S6 (Canada); Ruth, T.J. [Simon Fraser University, 8888 University Drive, Burnaby BC, V5A 1S6 (Canada); TRIUMF, Pet Group, 4004 Wesbrook Mall, Vancouver BC, V6T 2A3 (Canada)

    2007-03-15

    Cross-sections for the production of {sup 181}Re, {sup 182m}Re, {sup 182g}Re, {sup 183}Re, {sup 184}Re, and {sup 186}Re from proton bombardment of natural tungsten have been measured using the stacked foil technique for proton energies up to 17.6 MeV. Results are compared with the theoretical excitation functions as calculated by the EMPIRE II code (version 2.19) and experimental literature values. Results are in strong agreement with some of the previously reported literature as well at theoretical calculations for multiple reactions providing for more reliable estimates for the {sup 186}W(p, n){sup 186}Re reaction.

  3. Ion beam modifications of defect sub-structure of calcite cleavages

    Indian Academy of Sciences (India)

    E Venkateshwar Rao; M Ramakrishna Murthy

    2008-04-01

    Experimental investigations on the defect sub-structure and surface modifications, brought about by He+ ion-bombardment of calcite cleavages (100), have been carried out. Optical and scanning electron microscopic investigations revealed drastic modifications on the surface morphology, local symmetry and defect concentration. Additional structural defects on ion-bombardment of calcite surfaces also have been observed. Changes in shape and form of chemical etch pits are found to be a function of ion-beam energy, as studied by optical microscopy. Radiation damage in calcite has been attributed mainly due to desorption of CO$^{-2}_{3}$ ions from the calcite surfaces, on irradiation. Measurements of surface conductivity on irradiated calcite surfaces have been made employing a four-probe technique. Enhancement of surface conductivity has been considered to be due to an increase in concentration of CO$^{-2}_{3}$ ions formed, on ion irradiation and subsequent thermal stimulation. Planar plastic anisotropy has been studied on irradiated calcite cleavages by measurement of microhardness.

  4. Development of a permanent magnet alternative for a solenoidal ion source

    Energy Technology Data Exchange (ETDEWEB)

    Martens, J.; Fahy, A.; Barr, M. [Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308 (Australia); Jardine, A.; Allison, W. [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Dastoor, P.C., E-mail: Paul.Dastoor@newcastle.edu.au [Centre for Organic Electronics, University of Newcastle, Callaghan, NSW 2308 (Australia)

    2014-12-01

    The most sensitive desktop-sized ionizer utilising electron bombardment is currently the solenoidal ion source. We present an alternate design for such an ion source whereby the solenoidal windings of the electromagnet are replaced by a shaped cylindrical permanent magnet in order to reduce the complexity and running costs of the instrument. Through finite element modelling of the magnetic field in COMSOL and experimental measurements on a small-scale prototype magnet stack, we demonstrate the required shape of the permanent magnet in order to generate the needed field, and the necessity of soft iron collars to smooth fluctuations along the central axis.

  5. WSi2/Si Multilayer Sectioning by Reactive Ion Etching for Multilayer Laue Lens Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Bouet, N.; Conley, R.; Biancarosaa, J.; Divanc, R.; Macrander, A. T.

    2010-08-01

    SPIE Conference paper/talk presentation: Introduction: Reactive ion etching (RIE) has been employed in a wide range of fields such as semiconductor fabrication, MEMS (microelectromechanical systems), and refractive x-ray optics with a large investment put towards the development of deep RIE. Due to the intrinsic differing chemistries related to reactivity, ion bombardment, and passivation of materials, the development of recipes for new materials or material systems can require intense effort and resources. For silicon in particular, methods have been developed to provide reliable anisotropic profiles with good dimensional control and high aspect ratios1,2,3, high etch rates, and excellent material to mask etch selectivity...

  6. A quartz-crystal-microbalance technique to investigate ion-induced erosion of fusion relevant surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Golczewski, A. [Institut fuer Allgemeine Physik, TU Wien, Wiedner Hauptstr. 8-10/E134, Association EURATOM-OAW, A-1040 Vienna (Austria)], E-mail: golczewski@iap.tuwien.ac.at; Dobes, K.; Wachter, G.; Schmid, M. [Institut fuer Allgemeine Physik, TU Wien, Wiedner Hauptstr. 8-10/E134, Association EURATOM-OAW, A-1040 Vienna (Austria); Aumayr, F. [Institut fuer Allgemeine Physik, TU Wien, Wiedner Hauptstr. 8-10/E134, Association EURATOM-OAW, A-1040 Vienna (Austria)], E-mail: aumayr@iap.tuwien.ac.at

    2009-02-15

    We describe a highly sensitive quartz-crystal-microbalance technique capable of determining erosion as well as implantation and retention rates for fusion relevant surfaces under ion bombardment. Total sputtering yields obtained with this technique for Ar ion impact on polycrystalline gold and tungsten surfaces are presented. The results compare well with existing experimental data as well as theoretical predictions and thus demonstrate the feasibility of the developed technique. Our setup is capable of detecting mass-changes as small as 10{sup -5} {mu}g/s, which corresponds to a removal of only 10{sup -4} W monolayers/s.

  7. MEASUREMENTS OF TOTAL CROSS SECTIONS FOR K—SHELL IONIZATION BY ELECTRON BOMBARDMENT

    Institute of Scientific and Technical Information of China (English)

    李景文; 董志强; 等

    1994-01-01

    Cross sections for K-shell ionization have been measured at electron energies of 0.1-0.40MeV for Cu and Sn,and of 0.30MeV for Ag.The present results have been compared with theoretical calculations and previously reported experimental values.A great deal of experimental and theoretical work has been devoted in recent years to the study of the ionization cross sections of atoms or ions by electron impact[1-3],The importance of an accurate evaluation of these cross sections is evidenced by the wide variety of physical phenomana,the interpretations of which demand a knowledge of reaction rates for ionization by electron impact.Examples of such phenomena arise in the field of plamsa physics,in study of stellar atomospheres and the solar corona,in studies of gas discharges and of the passage of shock waves through gases,and in astrophysics.

  8. Compact device for cleaning scanner-mounted scanning tunneling microscope tips using electron bombardment

    Science.gov (United States)

    Hellmann, D.; Worbes, L.; Kittel, A.

    2011-08-01

    Most scanning probe techniques rely on the assumption that both sample and tip are free from adsorbates, residues, and oxide not deposited intentionally. Getting a clean sample surface can be readily accomplished by applying ion sputtering and subsequent annealing, whereas finding an adequate treatment for tips is much more complicated. The method of choice would effectively desorb undesired compounds without reducing the sharpness or the general geometry of the tip. Several devices which employ accelerated electrons to achieve this are described in the literature. To minimize both the effort to implement this technique in a UHV chamber and the overall duration of the cleaning procedure, we constructed a compact electron source fitted into a sample holder, which can be operated in a standard Omicron variable-temperature (VT)-STM while the tip stays in place. This way a maximum of compatibility with existing systems is achieved and short turnaround times are possible for tip cleaning.

  9. Multiple sectioning and perforation techniques for TEM sub-surface studies. [4 MeV Ni/sup +2/ ions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, E. H.; Rowcliffe, A. F.

    1978-01-01

    Techniques for preparing multiple electron transparent regions at several depth levels below the surface of a metal disk specimen are described. These techniques are relatively rapid and find application in many areas involving surface studies. Examples are shown of multiple thin areas produced at intervals of approximately 200 nm below the original surface of a stainless steel bombarded with 4 MeV Ni/sup +2/ ions for void swelling studies.

  10. The nature of keV and MeV ion damage in Al sub x Ga sub 1-x As/GaAs and AlAs/GaAs heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Cullis, A.G.; Smith, P.W.; Whitehouse, C.R. (DRA Electronics Div., Royal Signals and Radar Establishment, Malvern (United Kingdom)); Polman, A. (FOM-Inst. AMOLF, Amsterdam (Netherlands)); Jacobson, D.C.; Poate, J.M. (AT and T Bell Labs., Murray Hill, NJ (United States))

    1992-01-01

    Bombardment damage produced by Si{sup +} ions in Al{sub x}Ga{sub 1-x}As/GaAs layer structures has been studied using transmission electron microscopy, and ion channeling and backscattering spectrometry. The damage resistance of Al{sub x}Ga{sub 1-x}As alloy layers increases with Al concentration. In particular, using complementary Si{sup +} ion doses yielding similar nuclear displacement densities at 150 keV and 2 MeV bombardment energies, it is demonstrated for the first time that the local concentration of implanted Si impurity is likely to be a significant factor in controlling lattice damage build up. It is also shown for the first time that, in a manner analogous to AlAs, the alloy layers can confer a significant protection from ion damage upon adjacent narrow zones of crystalline GaAs, which exhibit enhanced resistance to damage accumulation. (orig.).

  11. Ordered SrTiO3 Nanoripples Induced by Fo cused Ion Beam

    Institute of Scientific and Technical Information of China (English)

    Jiang Wu; Gang Chen; Zhaoquan Zeng; Shibin Li; Xingliang Xu; Zhiming M Wang; Gregory J Salamo

    2012-01-01

    Ordered nanoripples on the niobium-doped SrTiO3 surfaces were fabricated through focused ion beam bombardment. The surface morphology of the SrTiO3 nanoripples was characterized using in situ focused ion beam/scanning electron microscopy. The well-aligned SrTiO3 nanostructures were obtained under optimized ion irradiation conditions. The characteristic wavelength was measured as about 210 nm for different ion beam currents. The relationship between the ion irradiation time and current and SrTiO3 surface morphology was analyzed. The presented method will be an effective supplement for fabrication of SrTiO3 nanostructures that can be used for ferroelectric and electronic applications.

  12. Molecular dynamics simulations of ion irradiation of a surface under an electric field

    Energy Technology Data Exchange (ETDEWEB)

    Parviainen, S., E-mail: stefan.parviainen@iki.fi; Djurabekova, F.

    2014-11-15

    The presence of high electric fields may affect significantly the process of sputtering of metal surfaces by energetic ions, especially in the vicinity of rough surface features. The effect can be significant if the energy of ions is fairly low. Moreover, the nanosized rough surface features – invisible to a naked eye, both intrinsic ones due to technological processing of surfaces and those forming because of sputtering – may affect the topology of surface erosion under ion bombardment. In this work we study by means of concurrent electrodynamics–molecular dynamics the sputtering yield of Cu{sup +} ions hitting a flat Cu surface or a nanosized Cu protrusion as a function of both ion energy and electric field strength. The results show that the sputtering yield is significantly enhanced in the presence of an electric field in both cases.

  13. Ion Colliders

    CERN Document Server

    Fischer, W

    2014-01-01

    High-energy ion colliders are large research tools in nuclear physics to study the Quark-Gluon-Plasma (QGP). The range of collision energy and high luminosity are important design and operational considerations. The experiments also expect flexibility with frequent changes in the collision energy, detector fields, and ion species. Ion species range from protons, including polarized protons in RHIC, to heavy nuclei like gold, lead and uranium. Asymmetric collision combinations (e.g. protons against heavy ions) are also essential. For the creation, acceleration, and storage of bright intense ion beams, limits are set by space charge, charge change, and intrabeam scattering effects, as well as beam losses due to a variety of other phenomena. Currently, there are two operating ion colliders, the Relativistic Heavy Ion Collider (RHIC) at BNL, and the Large Hadron Collider (LHC) at CERN.

  14. Secondary ion emission from CO2-H2O ice irradiated by energetic heavy ions: Part I. Measurement of the mass spectra

    Science.gov (United States)

    Farenzena, L. S.; Collado, V. M.; Ponciano, C. R.; da Silveira, E. F.; Wien, K.

    2005-05-01

    Secondary ion mass spectrometry is used to investigate ion emission from a frozen-gas mixture (T = 80-90 K) of CO2 and H2O bombarded by MeV nitrogen ions and by 252Cf fission fragments (FF). The aim of the experiments is to produce organic molecules in the highly excited material around the nuclear track and to detect them in the flux of sputtered particles. Such sputter processes are known to occur at the icy surfaces of planetary or interstellar objects. Time-of-flight (TOF) mass spectrometry is employed to identify the desorbed ions. Mass spectra of positive and negative ions were taken for several molecular H2O/CO2 ratios. In special, positive ions induced by MeV nitrogen beam were analyzed for 9 and 18% H2O concentrations of the CO2-H2O ice and negative ions for ~5% H2O. The ion peaks are separated to generate exclusive the spectra of CO2 specific ions, H2O specific ions and hybrid molecular ions, the latter ones corresponding to ions that contain mostly H and C atoms. In the mass range from 10 to 320 u, the latter exhibits 35 positive and 58 negative ions. The total yield of the positive ions is 0.35 and 0.57 ions/impact, respectively, and of negative ions 0.066 ions/impact. Unexpected effects of secondary ion sputtering yields on H2O/CO2 ratio are attributed to the influence of water molecules concentration on the ionization process.

  15. Effects of particle size, helium gas pressure and microparticle dose on the plasma concentration of indomethacin after bombardment of indomethacin-loaded poly-L-lactic acid microspheres using a Helios gun system.

    Science.gov (United States)

    Uchida, Masaki; Natsume, Hideshi; Kobayashi, Daisuke; Sugibayashi, Kenji; Morimoto, Yasunori

    2002-05-01

    We investigated the effects of the particle size of indomethacin-loaded poly-L-lactic acid microspheres (IDM-loaded PLA MS), the helium pressure used to accelerate the particles, and the bombardment dose of PLA MS on the plasma concentration of IDM after bombarding with IDM-loaded PLA MS of different particle size ranges, 20-38, 44-53 and 75-100 microm, the abdomen of hairless rats using the Helios gene gun system (Helios gun system). Using larger particles and a higher helium pressure, produced an increase in the plasma IDM concentration and the area under the plasma concentration-time curve (AUC) and resultant F (relative bioavailability with respect to intracutaneous injection) of IDM increased by an amount depending on the particle size and helium pressure. Although a reduction in the bombardment dose led to a decrease in C(max) and AUC, F increased on decreasing the bombardment dose. In addition, a more efficient F was obtained after bombarding with IDM-loaded PLA MS of 75-100 microm in diameter at each low dose in different sites of the abdomen compared with that after bolus bombardment with a high dose (dose equivalent). These results suggest that the bombardment injection of drug-loaded microspheres by the Helios gun system is a very useful tool for delivering a variety of drugs in powder form into the skin and systemic circulation.

  16. New experimental capability to investigate the hypervelocity micrometeoroid bombardment of cryogenic surfaces

    Science.gov (United States)

    Nelson, Andrew Oakleigh; Dee, Richard; Gudipati, Murthy S.; Horányi, Mihály; James, David; Kempf, Sascha; Munsat, Tobin; Sternovsky, Zoltán; Ulibarri, Zach

    2016-02-01

    Ice is prevalent throughout the solar system and beyond. Though the evolution of many of these icy surfaces is highly dependent on associated micrometeoroid impact phenomena, experimental investigation of these impacts has been extremely limited, especially at the impactor speeds encountered in space. The dust accelerator facility at the Institute for Modeling Plasmas, Atmospheres, and Cosmic Dust (IMPACT) of NASA's Solar System Exploration Research Virtual Institute has developed a novel cryogenic system that will facilitate future study of hypervelocity impacts into ice and icy regolith. The target consists of a copper block, cooled by liquid nitrogen, upon which layers of vapor-deposited ice, pre-frozen ice, or icy regolith can be built in a controlled and quantifiable environment. This ice can be grown from a variety of materials, including H2O, CH3OH, NH3, and slurries containing nanophase iron. Ice temperatures can be varied between 96 K and 150 K and ice thickness greater than 150 nm can be accurately measured. Importantly, the composition of ion plumes created during micrometeoroid impacts onto these icy layers can be measured even in trace amounts by in situ time-of-flight mass spectroscopy. In this paper, we present the fundamental design components of the cryogenic target chamber at IMPACT and proof-of-concept results from target development and from first impacts into thick layers of water ice.

  17. Cross-Linking Poly(lactic acid) Film Surface by Neutral Hyperthermal Hydrogen Molecule Bombardment.

    Science.gov (United States)

    Du, Wangli; Shao, Hong; He, Zhoukun; Tang, Changyu; Liu, Yu; Shen, Tao; Zhu, Yan; Lau, Woon-ming; Hui, David

    2015-12-16

    Constructing a dense cross-linking layer on a polymer film surface is a good way to improve the water resistance of poly(lactic acid) (PLA). However, conventional plasma treatments have failed to achieve the aim as a result of the unavoidable surface damage arising from the charged species caused by the uncontrolled high energy coming from colliding ions and electrons. In this work, we report a modified plasma method called hyperthermal hydrogen-induced cross-linking (HHIC) technology to construct a dense cross-linking layer on PLA film surfaces. This method produces energy-controlled neutral hyperthermal hydrogen, which selectively cleaves C-H bonds by molecule collision from the PLA film without breaking other bonds (e.g., C-C bonds in the polymer backbone), and results in subsequent cross-linking of the carbon radicals generated from the organic molecules. The formation of a dense cross-linking layer can serve as a barrier layer to significantly improve both the hydrophobicity and water vapor barrier property of the PLA film. Because of the advantage of selective cleavage of C-H bonds by HHIC treatment, the original physical properties (e.g., mechanical strength and light transmittance) of the PLA films are well-preserved.

  18. Ion energy distributions in bipolar pulsed-dc discharges of methane measured at the biased cathode

    Energy Technology Data Exchange (ETDEWEB)

    Corbella, C; Rubio-Roy, M; Bertran, E; Portal, S; Pascual, E; Polo, M C; Andujar, J L, E-mail: corbella@ub.edu [FEMAN Group, IN2UB, Departament de Fisica Aplicada i Optica, Universitat de Barcelona, c/ MartI i Franques 1, 08028 Barcelona (Spain)

    2011-02-15

    The ion fluxes and ion energy distributions (IED) corresponding to discharges in methane (CH{sub 4}) were measured in time-averaged mode with a compact retarding field energy analyser (RFEA). The RFEA was placed on a biased electrode at room temperature, which was powered by either radiofrequency (13.56 MHz) or asymmetric bipolar pulsed-dc (250 kHz) signals. The shape of the resulting IED showed the relevant populations of ions bombarding the cathode at discharge parameters typical in the material processing technology: working pressures ranging from 1 to 10 Pa and cathode bias voltages between 100 and 200 V. High-energy peaks in the IED were detected at low pressures, whereas low-energy populations became progressively dominant at higher pressures. This effect is attributed to the transition from collisionless to collisional regimes of the cathode sheath as the pressure increases. On the other hand, pulsed-dc plasmas showed broader IED than RF discharges. This fact is connected to the different working frequencies and the intense peak voltages (up to 450 V) driven by the pulsed power supply. This work improves our understanding in plasma processes at the cathode level, which are of crucial importance for the growth and processing of materials requiring controlled ion bombardment. Examples of industrial applications with these requirements are plasma cleaning, ion etching processes during fabrication of microelectronic devices and plasma-enhanced chemical vapour deposition of hard coatings (diamond-like carbon, carbides and nitrides).

  19. L X-ray emission induced by heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Pajek, M. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Banaś, D., E-mail: d.banas@ujk.edu.pl [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Braziewicz, J.; Majewska, U.; Semaniak, J. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Fijał-Kirejczyk, I. [The Institute of Atomic Energy, 05-400 Otwock-Świerk (Poland); Jaskóła, M.; Czarnacki, W.; Korman, A. [The National Centre for Nuclear Research, 05-400 Otwock-Świerk (Poland); Kretschmer, W. [Physikalisches Institut, Universität Erlangen-Nürnberg, D-91058 Erlangen (Germany); Mukoyama, T. [Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen (Hungary); Trautmann, D. [Institut für Physik, Universität Basel, Basel (Switzerland)

    2015-11-15

    Particle-induced X-ray emission (PIXE) technique is usually applied using typically 1 MeV to 3 MeV protons or helium ions, for which the ion-atom interaction is dominated by the single ionization process. For heavier ions the multiple ionization plays an increasingly important role and this process can influence substantially both the X-ray spectra and atomic decay rates. Additionally, the subshell coupling effects are important for the L- and M-shells ionized by heavy ions. Here we discuss the main features of the X-ray emission induced by heavy ions which are important for PIXE applications, namely, the effects of X-ray line shifts and broadening, vacancy rearrangement and change of the fluorescence and Coster–Kronig yields in multiple ionized atoms. These effects are illustrated here by the results of the measurements of L X-ray emission from heavy atoms bombarded by 6 MeV to 36 MeV Si ions, which were reported earlier. The strong L-subshell coupling effects are observed, in particular L{sub 2}-subshell, which can be accounted for within the coupling subshell model (CSM) developed within the semiclassical approximation. Finally, the prospects to use heavy ions in PIXE analysis are discussed.

  20. Ultralow energy ion beam surface modification of low density polyethylene.

    Science.gov (United States)

    Shenton, Martyn J; Bradley, James W; van den Berg, Jaap A; Armour, David G; Stevens, Gary C

    2005-12-01

    Ultralow energy Ar+ and O+ ion beam irradiation of low density polyethylene has been carried out under controlled dose and monoenergetic conditions. XPS of Ar+-treated surfaces exposed to ambient atmosphere show that the bombardment of 50 eV Ar+ ions at a total dose of 10(16) cm(-2) gives rise to very reactive surfaces with oxygen incorporation at about 50% of the species present in the upper surface layer. Using pure O+ beam irradiation, comparatively low O incorporation is achieved without exposure to atmosphere (approximately 13% O in the upper surface). However, if the surface is activated by Ar+ pretreatment, then large oxygen contents can be achieved under subsequent O+ irradiation (up to 48% O). The results show that for very low energy (20 eV) oxygen ions there is a dose threshold of about 5 x 10(15) cm(-2) before surface oxygen incorporation is observed. It appears that, for both Ar+ and O+ ions in this regime, the degree of surface modification is only very weakly dependent on the ion energy. The results suggest that in the nonequilibrium plasma treatment of polymers, where the ion flux is typically 10(18) m(-2) s(-1), low energy ions (<50 eV) may be responsible for surface chemical modification.

  1. L X-ray emission induced by heavy ions

    Science.gov (United States)

    Pajek, M.; Banaś, D.; Braziewicz, J.; Majewska, U.; Semaniak, J.; Fijał-Kirejczyk, I.; Jaskóła, M.; Czarnacki, W.; Korman, A.; Kretschmer, W.; Mukoyama, T.; Trautmann, D.

    2015-11-01

    Particle-induced X-ray emission (PIXE) technique is usually applied using typically 1 MeV to 3 MeV protons or helium ions, for which the ion-atom interaction is dominated by the single ionization process. For heavier ions the multiple ionization plays an increasingly important role and this process can influence substantially both the X-ray spectra and atomic decay rates. Additionally, the subshell coupling effects are important for the L- and M-shells ionized by heavy ions. Here we discuss the main features of the X-ray emission induced by heavy ions which are important for PIXE applications, namely, the effects of X-ray line shifts and broadening, vacancy rearrangement and change of the fluorescence and Coster-Kronig yields in multiple ionized atoms. These effects are illustrated here by the results of the measurements of L X-ray emission from heavy atoms bombarded by 6 MeV to 36 MeV Si ions, which were reported earlier. The strong L-subshell coupling effects are observed, in particular L2-subshell, which can be accounted for within the coupling subshell model (CSM) developed within the semiclassical approximation. Finally, the prospects to use heavy ions in PIXE analysis are discussed.

  2. Neutron Dose measurement in the carbon ion therapy area at HIRFL (IMP) as 12C ions with energies from 165 to 350MeV/u

    CERN Document Server

    Xu, Jun-Kui; Yan, Wei-Wei; Su, You-Wu; Li, Zong-Qiang; Wang, Mao; Pang, Cheng-Guo; Xu, Chong

    2016-01-01

    The neutron dose distributions on observation distances and on observation angles were measured using a Wendi-II neutron dose-meter at the deep tumor therapy terminal at HIRFL (Heavy Ion Research Facility in Lanzhou) as 12C ions with energies from 165 to 350 MeV/u bombarding on thick solid water targets with different thickness according to the ion energies. The experimental results were compared with those calculated by FLUKA code. It is found that the experimental data was in good agreement with the calculated results. The neutron energy spectra were also studied by using the FLUKA code. The results are valuable for the shielding design of high energy heavy ion medical machines and for the individual dose assessment.

  3. The fate of meteoric metals in ice particles: Effects of sublimation and energetic particle bombardment

    Science.gov (United States)

    Mangan, T. P.; Frankland, V. L.; Murray, B. J.; Plane, J. M. C.

    2017-08-01

    The uptake and potential reactivity of metal atoms on water ice can be an important process in planetary atmospheres and on icy bodies in the interplanetary and interstellar medium. For instance, metal atom uptake affects the gas-phase chemistry of the Earth's mesosphere, and has been proposed to influence the agglomeration of matter into planets in protoplanetary disks. In this study the fate of Mg and K atoms incorporated into water-ice films, prepared under ultra-high vacuum conditions at temperatures of 110-140 K, was investigated. Temperature-programmed desorption experiments reveal that Mg- and K-containing species do not co-desorb when the ice sublimates, demonstrating that uptake on ice particles causes irreversible removal of the metals from the gas phase. This implies that uptake on ice particles in terrestrial polar mesospheric clouds accelerates the formation of large meteoric smoke particles (≥1 nm radius above 80 km) following sublimation of the ice. Energetic sputtering of metal-dosed ice layers by 500 eV Ar+ and Kr+ ions shows that whereas K reacts on (or within) the ice surface to form KOH, adsorbed Mg atoms are chemically inert. These experimental results are consistent with electronic structure calculations of the metals bound to an ice surface, where theoretical adsorption energies on ice are calculated to be -68 kJ mol-1 for K, -91 kJ mol-1 for Mg, and -306 kJ mol-1 for Fe. K can also insert into a surface H2O to produce KOH and a dangling H atom, in a reaction that is slightly exothermic.

  4. 月球晚期重轰击和Nice模式%Lunar Late Heavy Bombardment and Nice model

    Institute of Scientific and Technical Information of China (English)

    陈丰; 王世杰

    2011-01-01

    The Late Heavy Bombardment (LHB), which is commonly referred to as the lunar cataclysm, is a period of approximate from 3.8 to 4.1 Ga when a large number of impact craters are believed to have been formed on the Moon, and is inferred that have happened on the Earth, the Mercury, the Venus, and the Mars as well. The Nice model is a dynamical evolution scenario of the Solar System. It was named after the location of the Observatory of the Cote of Azur, CNRS in Nice, France, where it was initially developed. Nice model proposes that giant planets migrated from initial compact configurations into their present positions, long after the dissipation of the initial protoplanetary gas disk. This planetary migration is used to explain historical events including the Late Heavy Bombardment of the inner Solar System, and the formation of the Oort cloud, the Kuiper belt, the Neptune and the Jupiter Trojans etc.%晚期重轰击(一般又称为月球灾难,简称LHB)指的是距今约3.8~4.1 Ga时段月球受到大量陨石的轰击,于月面上形成的大量撞击坑,并推论地球、水星、金星和火星也经历了这样一次重轰击.Nice模式是关于太阳系动力学演化的一种设想:在初始原行星气体星盘消散之后很久,大行星从最初紧凑的组构迁移到目前的位置.这个行星迁移理论用来解释包括内太阳系的晚期重轰击,以及Oort云、Kuiper带、海王星和木星Trojans行星等形成的历史事件.

  5. Implantation of anatase thin film with 100 keV {sup 56}Fe ions: Damage formation and magnetic behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, J. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden)], E-mail: Jens.Jensen@telia.com; Sanz, R. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, ES-28049 Madrid (Spain); Martin, D. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden); Surpi, A. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden); Department of Biology and Chemical Engineering, Maelardalens Hoegskola, SE-632 20 Eskilstuna (Sweden); Kubart, T. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden); Vazquez, M. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, ES-28049 Madrid (Spain); Hernandez-Velez, M. [Applied Physics Department, Universidad Autonoma de Madrid, ES-28049 Madrid (Spain)

    2009-08-15

    We have investigated the damage morphology and magnetic properties of titanium dioxide thin films following implantation with Fe ions. The titanium dioxide films, having a polycrystalline anatase structure, were implanted with 100 keV {sup 56}Fe{sup +} ions to a total fluence of 1.3 x 10{sup 16} ions/cm{sup 2}. The ion bombardment leads to an amorphized surface with no indication of the presence of secondary phases or Fe clusters. The ion-beam induced damage manifested itself by a marked change in surface morphology and film thickness. A room temperature ferromagnetic behaviour was observed by SQUID in the implanted sample. It is believed that the ion-beam induced damage and defects in the polycrystalline anatase film were partly responsible for the observed magnetic response.

  6. Advanced analysis tool for X-ray photoelectron spectroscopy profiling: Cleaning of perovskite SrTiO{sub 3} oxide surface using argon cluster ion source

    Energy Technology Data Exchange (ETDEWEB)

    Aureau, D., E-mail: damien.aureau@uvsq.fr [Institut Lavoisier de Versailles, (UMR 8180) Université de Versailles-Saint-Quentin-en-Yvelines–CNRS, 45 Av. des États-Unis, 78035 Versailles (France); Ridier, K. [Institut Lavoisier de Versailles, (UMR 8180) Université de Versailles-Saint-Quentin-en-Yvelines–CNRS, 45 Av. des États-Unis, 78035 Versailles (France); Groupe d' Étude de la Matière Condensée (UMR 8635) Université de Versailles Saint-Quentin-en-Yvelines–CNRS, 45 Av. des États-Unis, 78035 Versailles (France); Bérini, B.; Dumont, Y.; Keller, N. [Groupe d' Étude de la Matière Condensée (UMR 8635) Université de Versailles Saint-Quentin-en-Yvelines–CNRS, 45 Av. des États-Unis, 78035 Versailles (France); Vigneron, J.; Bouttemy, M.; Etcheberry, A. [Institut Lavoisier de Versailles, (UMR 8180) Université de Versailles-Saint-Quentin-en-Yvelines–CNRS, 45 Av. des États-Unis, 78035 Versailles (France); Fouchet, A. [Groupe d' Étude de la Matière Condensée (UMR 8635) Université de Versailles Saint-Quentin-en-Yvelines–CNRS, 45 Av. des États-Unis, 78035 Versailles (France)

    2016-02-29

    This article shows the comparison between three different ionic bombardments during X-ray photoelectron spectroscopy (XPS) studies of single crystalline SrTiO{sub 3} (STO) substrates. The abrasion using a “cluster argon ion source” is compared with the standard “monoatomic Ar”. The influence of the energy of the monoatomic ions used is clearly demonstrated. While the chemically adsorbed species on the STO surface are removed, such bombardment strongly modifies the surface. A reduction of part of the titanium atoms and the appearance of a different chemical environment for surface strontium atoms are observed. Implantation of argon ions is also detected. Cluster ion etching is used on oxide surface and, in this case only, due to a much lower kinetic energy per atom compared to monoatomic ions, the possibility to remove surface contaminants at the surface without modification of the XP spectra is clearly demonstrated, ensuring that the stoichiometry of the surface is preserved. Such result is crucial for everybody working with oxide surfaces to obtain a non-modified XPS analysis. The progressive effect of this powerful tool allows the monitoring of the removal of surface contamination in the first steps of the bombardment which was not achievable with usual guns. - Highlights: • The effects of three argon etchings are studied as a function of time on SrTiO3 oxide. • A method for obtaining non-modified chemical analysis of oxides is presented. • The soft removal of adsorbed species thanks to argon cluster is demonstrated. • The damages induced on SrTiO3 surface by ionic bombardment are shown. • The influence of the kinetic energy of incoming Ar atoms is examined.

  7. Recent studies in heavy ion induced fission reactions

    Science.gov (United States)

    Choudhury, R. K.

    2001-08-01

    Nuclear fission process involves large scale shape changes of the nucleus, while it evolves from a nearly spherical configuration to two separated fission fragments. The dynamics of these shape changes in the nuclear many body system is governed by a strong interplay of the collective and single particle degrees of freedom. With the availability of heavy ion accelerators, there has been an impetus to study the nuclear dynamics through the investigations of nucleus--nucleus collisions involving fusion and fission process. From the various investigations carried out in the past years, it is now well recognized that there is large scale damping of collective modes in heavy ion induced fission reactions, which in other words implies that nuclear motion is highly viscous. In recent years, there have been many experimental observations in heavy ion induced fission reactions at medium bombarding energies, which suggest possible occurrence of various non-equilibrium modes of fission such as quasi-fission, fast fission and pre-equilibrium fission, where some of the internal degrees of freedom of the nucleus is not fully equilibrated. We have carried out extensive investigations on the fission fragment angular distributions at near barrier bombarding energies using heavy fissile targets. The measured fragment anisotropies when compared with the standard saddle point model (SSPM) calculations show that for projectile-target systems having zero or low ground state spins, the angular anisotropy exhibits a peak-like behaviour at the sub barrier energies, which cannot be explained by the SSPM calculations. For projectiles or targets with large ground state spins, the anomalous peaking gets washed out due to smearing of the K-distribution by the intrinsic entrance channel spins. Recently studies have been carried out on the spin distributions of fission fragments through the gamma ray multiplicity measurements. The fission fragments acquire spin mainly from two sources: (i) due to

  8. A novel ion-beam-mutation effect application in identification of gene involved in bacterial antagonism to fungal infection of ornamental crops

    Energy Technology Data Exchange (ETDEWEB)

    Mahadtanapuk, S. [Faculty of Agriculture and Natural Resources, University of Phayao, Maeka, Muang, Phayao 56000 (Thailand); Teraarusiri, W. [Central Laboratory, University of Phayao, Maeka, Muang, Phayao 56000 (Thailand); Nanakorn, W. [The Crown Property Bureau, 173 Nakhonratchasrima Road, Dusit, Bangkok 10300 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Thongkumkoon, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Anuntalabhochai, S., E-mail: soanu.1@gmail.com [Molecular Biology Laboratory, Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-05-01

    Highlights: • Ion beam bombardment induced mutation in bacterial B. licheniformis. • A mutant lost antifungal activity. • DNA fingerprint of the mutant was analyzed. • The lost gene was indentified to code for TrxR gene. • TrxR gene from B. licheniformis expressed the flower antagonism to fungi. - Abstract: This work is on a novel application of ion beam effect on biological mutation. Bacillus licheniformis (B. licheniformis) is a common soil bacterium with an antagonistic effect on Curcuma alismatifolia Gagnep. and Chrysanthemum indicum Linn. In an attempt to control fungal diseases of local crops by utilizing B. licheniformis, we carried out gene analysis of the bacterium to understand the bacterial antagonistic mechanism. The bacterial cells were bombarded to induce mutations using nitrogen ion beam. After ion bombardment, DNA analysis revealed that the modified polymorphism fragment present in the wild type was missing in a bacterial mutant which lost the antifungal activity. The fragments conserved in the wild type but lost in the mutant bacteria was identified to code for the thioredoxin reductase (TrxR) gene. The gene analysis showed that the TrxR gene from B. licheniformis had the expression of the antagonism to fungi in a synchronous time evolution with the fungus inhibition when the bacteria were co-cultivated with the fungi. The collective results indicate the TrxR gene responsible for the antagonism of bacteria B. licheniformis to fungal infection.

  9. A C60 primary ion beam system for time of flight secondary ion mass spectrometry: its development and secondary ion yield characteristics.

    Science.gov (United States)

    Weibel, Daniel; Wong, Steve; Lockyer, Nicholas; Blenkinsopp, Paul; Hill, Rowland; Vickerman, John C

    2003-04-01

    A buckminsterfullerene (C60)-based primary ion beam system has been developed for routine application in TOF-SIMS analysis of organic materials. The ion beam system is described, and its performance is characterized. Nanoamp beam currents of C60+ are obtainable in continuous current mode. C60(2+) can be obtained in pulsed mode. At 10 keV, the beam can be focused to less than 3 microm with 0.1 nA currents. TOF-SIMS studies of a series of molecular solids and a number of polymer systems in monolayer and thick film forms are reported. Very significant enhancement of secondary ion yields, particularly at higher mass, were observed using 10-keV C60+ for all samples other than PTFE, as compared to those observed from 10 keV Ga+ primary ions. Three materials (PS2000, Irganox 1010, PET) were studied in detail to investigate primary ion-induced disappearance (damage) cross sections to determine the increase in secondary ion formation efficiency. The C60 disappearance cross sections observed from monolayer film PS2000 and self-supporting PET film are close to those observed from Ga+. The resulting C60 efficiencies are 30-100 times those observed from gallium. The cross sections observed from C60 bombardment of multilayer molecular solids are approximately 100 times less, such that essentially zero damage sputtering is possible. The resulting efficiencies are > 10(3) greater than from gallium. It is also shown that C60 primary ions do not generate any more low-mass fragments than any other ion beam system does. C60 is shown to be a very favorable ion beam system for TOF-SIMS, delivering high yield, close to 10% total yield, favoring high-mass ions, and on thick samples, offering the possibility of analysis well beyond the static limit.

  10. Metabolism of cycloate in radish leaf: metabolite identification by packed capillary flow fast atom bombardment tandem mass spectrometry.

    Science.gov (United States)

    Onisko, B C; Barnes, J P; Staub, R E; Walker, F H; Kerlinger, N

    1994-10-01

    The metabolism of cycloate, a thiocarbamate herbicide, was investigated in mature radish leaf. Twelve new metabolites were identified by liquid chromatographic/mass spectrometric analysis using fast atom bombardment and packed capillary liquid chromatography columns. Full-scan and tandem mass spectrometric methods were employed. Application of the on-column focusing technique resulted in identifications with injections of as little as 15 ng of metabolite (20 ppb in radish). This injection technique allows the practical use of packed capillary liquid chromatography/mass spectrometry in sample-limited applications. Cycloate is oxidized to several ring-hydroxylated isomers that are subsequently glucosylated and esterified with malonic acid. Cycloate is also conjugated with glutathione. Metabolic hydrolysis of the glutathione conjugate formed a cysteine conjugate that is further metabolized by amidation with either malonic or acetic acid. Transamination of the cysteine conjugate gave a thiolactic acid derivative. Metabolites were also identified that were the result of both ring-hydroxylation and conjugation with glutathione. One of these, an N-acetylcysteine conjugate, is the first report of a mercapturic acid in plants. The structures of two of the new metabolites were confirmed by chemical synthesis.

  11. Measurement of activation reaction rate distributions in a lead assembly bombarded with 500-MeV protons

    CERN Document Server

    Takada, H; Sasa, T; Tsujimoto, K; Yasuda, H

    2000-01-01

    Reaction rate distributions of various activation detectors such as the /sup nat/Ni(n, x)/sup 58/Co, /sup 197/Au(n,2n)/sup 196/Au, and /sup 197/Au(n,4n)/sup 194/Au reactions were measured to study the production and the transport of spallation neutrons in a lead assembly bombarded with protons of 500 MeV. The measured data were analyzed with the nucleon-meson transport code NMTC/JAERI combined with the MCNP4A code using the nuclide production cross sections based on the JENDL Dosimetry File and those calculated with the ALICE-F code. It was found that the NMTC/JAERI-MCNP4A calculations agreed well with the experiments for the low-energy-threshold reaction of /sup nat/Ni(n, x)/sup 58/Co. With the increase of threshold energy, however, the calculation underestimated the experiments, especially above 20 MeV. The reason for the disagreement can be attributed to the underestimation of the neutron yield in the tens of mega-electron-volt regions by the NMTC/JAERI code. (32 refs).

  12. Zero-Phonon Transition and Spectral Hole Burning of Colour Centres in Doped Lithium Fluoride Crystals Bombarded by Electrons

    Institute of Scientific and Technical Information of China (English)

    顾洪恩; 王克起; 刘洪海

    2001-01-01

    Two zero-phonon lines with wide linewidth on R1- and unknown colour centres have been observed in the magnesium-doped lithium fluoride crystals coloured by electron beam bombardment at 200 K in the measured temperature range of 10-77 K. The R1- zero-phonon line can be nearly completely bleached using the normal spectrophotometer light at 10K. An obvious spectral burning hole in the absorption profile of the R1- zero-phonon line of colour centres in the coloured lithium fluoride crystals has been obtained by using the spectrophotometer light adjusted to narrower bandwidth at 10K. The optical bleaching of the zero-phonon line can be partially recovered by annealing the crystals to room temperature for a short time period or irradiating the crystals with ultraviolet light above 40 K, and nearly complete restoration can be obtained after the ultraviolet light irradiation and storage in the dark for a long time at room temperature.

  13. Development of hydrophobicity of mica surfaces by ion beam sputtering

    Science.gov (United States)

    Metya, Amaresh; Ghose, Debabrata; Ray, Nihar Ranjan

    2014-02-01

    The hydrophilic mica surface can be made hydrophobic by low energy Ar+ ion sputtering. The ion sputtering leads to both topographical and physicochemical changes of the surface which are thought to be responsible for the water repelling behavior. The sessile drop method is used to evaluate the wetting properties of the sputtered mica surfaces. It has been shown that the sputter-pattern at the nano-length scale has little influence on the development of hydrophobicity. On the other hand, the wettability appears to be strongly connected with the chemistry of the bombarded surface. We have also studied the temporal evolution of contact angle as the water evaporates due to difference in vapor pressures between the droplet surface and the surroundings. The analysis offers a simple method to estimate the diffusion coefficient of water vapor.

  14. Development of hydrophobicity of mica surfaces by ion beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Metya, Amaresh; Ghose, Debabrata, E-mail: debabrata.ghose@saha.ac.in; Ray, Nihar Ranjan

    2014-02-28

    The hydrophilic mica surface can be made hydrophobic by low energy Ar{sup +} ion sputtering. The ion sputtering leads to both topographical and physicochemical changes of the surface which are thought to be responsible for the water repelling behavior. The sessile drop method is used to evaluate the wetting properties of the sputtered mica surfaces. It has been shown that the sputter-pattern at the nano-length scale has little influence on the development of hydrophobicity. On the other hand, the wettability appears to be strongly connected with the chemistry of the bombarded surface. We have also studied the temporal evolution of contact angle as the water evaporates due to difference in vapor pressures between the droplet surface and the surroundings. The analysis offers a simple method to estimate the diffusion coefficient of water vapor.

  15. Ion Chromatography.

    Science.gov (United States)

    Mulik, James D.; Sawicki, Eugene

    1979-01-01

    Accurate for the analysis of ions in solution, this form of analysis enables the analyst to directly assay many compounds that previously were difficult or impossible to analyze. The method is a combination of the methodologies of ion exchange, liquid chromatography, and conductimetric determination with eluant suppression. (Author/RE)

  16. Genetic transformation of Indian bread (T. aestivum) and pasta (T. durum) wheat by particle bombardment of mature embryo-derived calli

    OpenAIRE

    Khurana Paramjit; Patnaik Debasis

    2003-01-01

    Abstract Background Particle bombardment has been successfully employed for obtaining transgenics in cereals in general and wheat in particular. Most of these procedures employ immature embryos which are not available throughout the year. The present investigation utilizes mature seeds as the starting material and the calli raised from the hexaploid Triticum aestivum and tetraploid Triticum durum display a high regeneration response and were therefore used as the target tissue for genetic tra...

  17. Estimations and integral measurements for the spectral yield of neutrons from thick beryllium target bombarded with 16 MeV protons

    CERN Document Server

    Fenyvesi, A

    2015-01-01

    Spectral yield of p+Be neutrons emitted by thick (stopping) beryllium target bombarded by 16 MeV protons was estimated via extrapolation of literature data. The spectrum was validated via multi-foil activation method and irradiation of 2N2222 transistors. The hardness parameter (NIEL scaling factor) for displacement damage in bulk silicon was calculated and measured and kappa = 1.26 +- 0.1 was obtained.

  18. Time-of-flight secondary neutral & ion mass spectrometry using swift heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, L.; Meinerzhagen, F. [Universität Duisburg-Essen, Fakultät für Physik, D-47048 Duisburg (Germany); Bender, M.; Severin, D. [Gesellschaft für Schwerionenforschung GSI, D-64291 Darmstadt (Germany); Wucher, A., E-mail: andreas.wucher@uni-due.de [Universität Duisburg-Essen, Fakultät für Physik, D-47048 Duisburg (Germany)

    2015-12-15

    We report on a new time-of-flight (TOF) spectrometer designed to investigate sputtering phenomena induced by swift heavy ions in the electronic stopping regime. In this experiment, particular emphasis is put on the detection of secondary ions along with their emitted neutral counterparts in order to examine the ionization efficiency of the sputtered material. For the detection of neutral species, the system is equipped with a pulsed VUV laser for post-ionization of sputtered neutral atoms and molecules via single photon ionization at a wavelength of 157 nm (corresponding to 7.9 eV photon energy). For alignment purposes and in order to facilitate comparison to nuclear sputtering conditions, the system also includes a 5 keV Ar{sup +} ion beam directed to the same sample area. The instrument has been added to the M1-branch beam line at the German accelerator facility in Darmstadt (GSI) and was tested with 4.8 MeV/u Au{sup 26+} ions impinging onto various samples including metals, salts and organic films. It is found that secondary ion and neutral spectra obtained under both bombardment conditions can be acquired in an interleaved manner throughout a single accelerator pulse cycle, thus making efficient use of valuable beam time. In addition, the keV ion beam can be intermittently switched to dc mode between subsequent data acquisition windows and accelerator pulses in order to ensure reproducible surface conditions. For the case of a dynamically sputter cleaned metal surface, comparison of secondary ion and neutral signals obtained under otherwise identical instrumental conditions reveals a nearly identical ionization probability of atoms emitted under electronic and nuclear sputtering conditions.

  19. Optimization of Energy Scope for Titanium Nitride Films Grown by Ion Beam-Assisted Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Wei; MA Zhong-Quan; WANG Ye; WANG De-Ming

    2006-01-01

    The deposited energy during film growth with ion bombardment, correlated to the atomic displacement on the surface monolayer and the underlying bulk, has been calculated by a simplified ion-solid interaction model under binary collision approximation. The separated damage energies caused by Ar ion, different for the surface and the bulk, have been determined under the standard collision cross section and a well-defined surface and bulk atom displacement threshold energy of titanium nitride (TiN). The optimum energy scope shows that the incident energy of Ar+ around 110eV for TiN (111) and 80eV for TiN (200) effectively enhances the mobility of adatom on surface but excludes the damage in underlying bulk. The theoretical prediction and the experimental result are in good agreement in low energy ion beam-assisted deposition.

  20. Surface charging of thick porous water ice layers relevant for ion sputtering experiments

    Science.gov (United States)

    Galli, A.; Vorburger, A.; Pommerol, A.; Wurz, P.; Jost, B.; Poch, O.; Brouet, Y.; Tulej, M.; Thomas, N.

    2016-07-01

    We use a laboratory facility to study the sputtering properties of centimeter-thick porous water ice subjected to the bombardment of ions and electrons to better understand the formation of exospheres of the icy moons of Jupiter. Our ice samples are as similar as possible to the expected moon surfaces but surface charging of the samples during ion irradiation may distort the experimental results. We therefore monitor the time scales for charging and discharging of the samples when subjected to a beam of ions. These experiments allow us to derive an electric conductivity of deep porous ice layers. The results imply that electron irradiation and sputtering play a non-negligible role for certain plasma conditions at the icy moons of Jupiter. The observed ion sputtering yields from our ice samples are similar to previous experiments where compact ice films were sputtered off a micro-balance.

  1. Nano-ranged low-energy ion-beam-induced DNA transfer in biological cells

    Science.gov (United States)

    Yu, L. D.; Wongkham, W.; Prakrajang, K.; Sangwijit, K.; Inthanon, K.; Thongkumkoon, P.; Wanichapichart, P.; Anuntalabhochai, S.

    2013-06-01

    Low-energy ion beams at a few tens of keV were demonstrated to be able to induce exogenous macromolecules to transfer into plant and bacterial cells. In the process, the ion beam with well controlled energy and fluence bombarded living cells to cause certain degree damage in the cell envelope in nanoscales to facilitate the macromolecules such as DNA to pass through the cell envelope and enter the cell. Consequently, the technique was applied for manipulating positive improvements in the biological species. This physical DNA transfer method was highly efficient and had less risk of side-effects compared with chemical and biological methods. For better understanding of mechanisms involved in the process, a systematic study on the mechanisms was carried out. Applications of the technique were also expanded from DNA transfer in plant and bacterial cells to DNA transfection in human cancer cells potentially for the stem cell therapy purpose. Low-energy nitrogen and argon ion beams that were applied in our experiments had ranges of 100 nm or less in the cell envelope membrane which was majorly composed of polymeric cellulose. The ion beam bombardment caused chain-scission dominant damage in the polymer and electrical property changes such as increase in the impedance in the envelope membrane. These nano-modifications of the cell envelope eventually enhanced the permeability of the envelope membrane to favor the DNA transfer. The paper reports details of our research in this direction.

  2. Nano-ranged low-energy ion-beam-induced DNA transfer in biological cells

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.D., E-mail: yuld@fnrf.science.cmu.ac.th [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wongkham, W. [Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Sangwijit, K.; Inthanon, K. [Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thongkumkoon, P. [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wanichapichart, P. [Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Membrane Science and Technology Research Center, Department of Physics, Faculty of Science, Prince of Songkla University, Hat Yai, Songkla 90112 (Thailand); Anuntalabhochai, S. [Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2013-06-15

    Low-energy ion beams at a few tens of keV were demonstrated to be able to induce exogenous macromolecules to transfer into plant and bacterial cells. In the process, the ion beam with well controlled energy and fluence bombarded living cells to cause certain degree damage in the cell envelope in nanoscales to facilitate the macromolecules such as DNA to pass through the cell envelope and enter the cell. Consequently, the technique was applied for manipulating positive improvements in the biological species. This physical DNA transfer method was highly efficient and had less risk of side-effects compared with chemical and biological methods. For better understanding of mechanisms involved in the process, a systematic study on the mechanisms was carried out. Applications of the technique were also expanded from DNA transfer in plant and bacterial cells to DNA transfection in human cancer cells potentially for the stem cell therapy purpose. Low-energy nitrogen and argon ion beams that were applied in our experiments had ranges of 100 nm or less in the cell envelope membrane which was majorly composed of polymeric cellulose. The ion beam bombardment caused chain-scission dominant damage in the polymer and electrical property changes such as increase in the impedance in the envelope membrane. These nano-modifications of the cell envelope eventually enhanced the permeability of the envelope membrane to favor the DNA transfer. The paper reports details of our research in this direction.

  3. Effects of metal nanoparticles on the secondary ion yields of a model alkane molecule upon atomic and polyatomic projectiles in secondary ion mass spectrometry.

    Science.gov (United States)

    Wehbe, Nimer; Heile, Andreas; Arlinghaus, Heinrich F; Bertrand, Patrick; Delcorte, Arnaud

    2008-08-15

    A model alkane molecule, triacontane, is used to assess the effects of condensed gold and silver nanoparticles on the molecular ion yields upon atomic (Ga(+) and In(+)) and polyatomic (C60(+) and Bi3(+)) ion bombardment in metal-assisted secondary ion mass spectrometry (MetA-SIMS). Molecular films spin-coated on silicon were metallized using a sputter-coater system, in order to deposit controlled quantities of gold and silver on the surface (from 0 to 15 nm equivalent thickness). The effects of gold and silver islets condensed on triacontane are also compared to the situation of thin triacontane overlayers on metallic substrates (gold and silver). The results focus primarily on the measured yields of quasi-molecular ions, such as (M - H)(+) and (2M - 2H)(+), and metal-cationized molecules, such as (M + Au)(+) and (M + Ag)(+), as a function of the quantity of metal on the surface. They confirm the absence of a simple rule to explain the secondary ion yield improvement in MetA-SIMS. The behavior is strongly dependent on the specific projectile/metal couple used for the experiment. Under atomic bombardment (Ga(+), In(+)), the characteristic ion yields an increase with the gold dose up to approximately 6 nm equivalent thickness. The yield enhancement factor between gold-metallized and pristine samples can be as large as approximately 70 (for (M - H)(+) under Ga(+) bombardment; 10 nm of Au). In contrast, with cluster projectiles such as Bi3(+) and C60(+), the presence of gold and silver leads to a dramatic molecular ion yield decrease. Cluster projectiles prove to be beneficial for triacontane overlayers spin-coated on silicon or metal substrates (Au, Ag) but not in the situation of MetA-SIMS. The fundamental difference of behavior between atomic and cluster primary ions is tentatively explained by arguments involving the different energy deposition mechanisms of these projectiles. Our results also show that Au and Ag nanoparticles do not induce the same behavior in Met

  4. Ranges, Reflection and Secondary Electron Emission for keV Hydrogen Ions Incident on Solid N2

    DEFF Research Database (Denmark)

    Børgesen, P.; Sørensen, H.; Hao-Ming, Chen

    1983-01-01

    Ranges were measured for 0.67–3.3 keV/amu hydrogen and deuterium ions in solid N2. Comparisons with similar results for N2-gas confirm the previously observed large phase effect in the stopping cross section. Measurements of the secondary electron emission coefficient for bulk solid N2 bombarded...... by 0.67–9 keV/amu ions also seem to support such a phase effect. It is argued that we may also extract information about the charge state of reflected projectiles....

  5. Material-dependent amorphization and epitaxial crystallization in ion-implanted AlAs/GaAs layer structures

    Energy Technology Data Exchange (ETDEWEB)

    Cullis, A.G.; Chew, N.G.; Whitehouse, C.R. (Royal Signals and Radar Establishment, St. Andrews Road, Malvern, Worcestershire WR14 3PS, United Kingdom (GB)); Jacobson, D.C.; Poate, J.M.; Pearton, S.J. (AT T Bell Laboratories, 600 Mountain Avenue, Murray Hill, New Jersey 07974)

    1989-09-18

    When AlAs/GaAs layer samples are subjected to Ar{sup +} ion bombardment at liquid-nitrogen temperature, it is shown that very different damage structures are produced in the two materials. While the GaAs is relatively easily amorphized, the AlAs is quite resistant to damage accumulation and remains crystalline for the ion doses employed in these investigations. Epitaxial regrowth of buried amorphous GaAs layers of thicknesses up to 150 nm can be induced by rapid thermal annealing. It is demonstrated that differences in the initial damage state have a strong influence upon the nature of lattice defects produced by annealing.

  6. Scanning-probe-microscopy of polyethylene terephthalate surface treatment by argon ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Espinoza-Beltran, Francisco [Polymer & Biopolymer Group, Libramiento Norponiente no. 2000, Cinvestav Queretaro, Queretaro 76230 (Mexico); Sanchez, Isaac C. [Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); España-Sánchez, Beatriz L.; Mota-Morales, Josué D.; Carrillo, Salvador; Enríquez-Flores, C.I. [Polymer & Biopolymer Group, Libramiento Norponiente no. 2000, Cinvestav Queretaro, Queretaro 76230 (Mexico); Poncin-Epaillard, Fabienne, E-mail: epaill@univ-lemans.fr [Institute for Molecules and Materials, UMR CNRS 6283, Av. O. Messiaen, Universitè du Maine, Le Mans 72085 (France); Luna-Barcenas, Gabriel, E-mail: gluna@qro.cinvestav.mx [Polymer & Biopolymer Group, Libramiento Norponiente no. 2000, Cinvestav Queretaro, Queretaro 76230 (Mexico)

    2015-11-01

    Highlights: • Kelvin-probe-force microscopy helps study of PET surface treated by Ar ion beam. • Ar ion beam surface treatment promotes chain scission and N insertion. • Surface roughness and work function increases as intensity of ion energy increases. • Adhesive force of PET decrease due to the surface changes by ion bombardment. - Abstract: The effect of argon (Ar{sup +}) ion beam treatment on the surface of polyethylene terephthalate (PET) samples was studied by scanning probe microscopy (SPM) and the changes in surface topography were assessed by atomic force microscopy (AFM). Kelvin probe force microscopy (KPFM) sheds light of adhesion force between treated polymer films and a Pt/Cr probe under dry conditions, obtaining the contact potential difference of material. As a result of Ar{sup +} ion bombardment, important surface chemical changes were detected by X-ray photoelectron spectroscopy (XPS) measurements such as chains scission and incorporation of nitrogen species. Ion beam treatment increases the surface roughness from 0.49 ± 0.1 nm to 7.2 ± 0.1 nm and modify the surface potential of PET samples, decreasing the adhesive forces from 12.041 ± 2.1 nN to 5.782 ± 0.06 nN, and producing a slight increase in the electronic work function (Φ{sub e}) from 5.1 V (untreated) to 5.2 V (treated). Ar{sup +} ion beam treatment allows to potentially changing the surface properties of PET, modifying surface adhesion, improving surface chemical changes, wetting properties and surface potential of polymers.

  7. SPITZER EVIDENCE FOR A LATE-HEAVY BOMBARDMENT AND THE FORMATION OF UREILITES IN {eta} CORVI At {approx}1 Gyr

    Energy Technology Data Exchange (ETDEWEB)

    Lisse, C. M. [JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Wyatt, M. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Chen, C. H. [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Morlok, A. [Department of Earth and Planetary Sciences, The Open University, Milton-Keynes (United Kingdom); Watson, D. M.; Manoj, P.; Sheehan, P. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Currie, T. M. [NASA-GSFC, Code 667, Greenbelt, MD 20771 (United States); Thebault, P. [Observatoire de Paris, F-92195 Meudon Principal Cedex (France); Sitko, M. L., E-mail: carey.lisse@jhuapl.edu, E-mail: wyatt@ast.cam.ac.uk, E-mail: cchen@stsci.edu, E-mail: a.morlok@open.ac.uk, E-mail: dmw@pas.rochester.edu, E-mail: manoj@pas.rochester.edu, E-mail: psheeha2@mail.rochester.edu, E-mail: thayne.m.currie@nasa.gov, E-mail: philippe.thebault@obspm.fr, E-mail: sitko@spacescience.org [Space Science Institute, 475 Walnut Street, Suite 205, Boulder, CO 80301 (United States)

    2012-03-10

    We have analyzed Spitzer and NASA/IRTF 2-35 {mu}m spectra of the warm, {approx}350 K circumstellar dust around the nearby MS star {eta} Corvi (F2V, 1.4 {+-} 0.3 Gyr). The spectra show clear evidence for warm, water- and carbon-rich dust at {approx}3 AU from the central star, in the system's terrestrial habitability zone. Spectral features due to ultra-primitive cometary material were found, in addition to features due to impact produced silica and high-temperature carbonaceous phases. At least 9 Multiplication-Sign 10{sup 18} kg of 0.1-100 {mu}m warm dust is present in a collisional equilibrium distribution with dn/da {approx} a{sup -3.5}, the equivalent of a 130 km radius Kuiper Belt object (KBO) of 1.0 g cm{sup 3} density and similar to recent estimates of the mass delivered to the Earth at 0.6-0.8 Gyr during the late-heavy bombardment. We conclude that the parent body was a Kuiper Belt body or bodies which captured a large amount of early primitive material in the first megayears of the system's lifetime and preserved it in deep freeze at {approx}150 AU. At {approx}1.4 Gyr they were prompted by dynamical stirring of their parent Kuiper Belt into spiraling into the inner system, eventually colliding at 5-10 km s{sup -1} with a rocky planetary body of mass {<=}M{sub Earth} at {approx}3 AU, delivering large amounts of water (>0.1% of M{sub Earth'sOceans}) and carbon-rich material. The Spitzer spectrum also closely matches spectra reported for the Ureilite meteorites of the Sudan Almahata Sitta fall in 2008, suggesting that one of the Ureilite parent bodies was a KBO.

  8. Neutron spectra from 647- and 800-MeV proton bombardment of hydrogen and deuterium. [Cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Bjork, C.W.

    1975-12-01

    Zero degree neutron spectra for the inclusive reactions p(p,n) and d(p,n) were obtained. Spectra were obtained for bombarding proton kinetic energies of 647 and 800 MeV. The strongly peaked p(p,n) spectra are well explained via the p(p,n)p..pi../sup +/ reaction primarily through the production of the N*/sub 33/(..delta../sup + +/) resonance. However, there is evidence for n-p final state interactions as well. Calculations have shown the roles of the N*/sub 33/ resonance and the n-p final state interactions in these p(p,n) spectra. The d(p,n) spectra exhibit a strong quasi-elastic charge exchange peak influenced by the final state p-p interaction in the reaction d(p,n)2p. The d(p,n) spectra also show a broad bump at lower neutron momenta qualitatively similar to the p(p,n) spectra. The d(p,n) spectra at lower momenta are nearly explained by nucleon-nucleon single pion production via the N*/sub 33/ resonance but it appears that higher order contributions involving nucleon--nucleon and nucleon--pion interactions are required as well. The d(p,n)2p reaction provides an intense, nearly monoenergetic neutron beam for use as a probe, primarily of the n-p interaction, at medium energies. The d(p,n) and p(p,n) measurements provide zero degree neutron momentum distributions which are very useful in furthering the knowledge about pion production near the N*/sub 33/ resonance. These data provide a challenge to the theoreticians to explain pion production in the two and three nucleon initial states. (auth)

  9. STABILITY OF EXTRATERRESTRIAL GLYCINE UNDER ENERGETIC PARTICLE RADIATION ESTIMATED FROM 2 keV ELECTRON BOMBARDMENT EXPERIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Maté, B.; Tanarro, I.; Escribano, R.; Moreno, M. A.; Herrero, V. J. [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 123, E-28006 Madrid (Spain)

    2015-06-20

    The destruction of solid glycine under irradiation with 2 keV electrons has been investigated by means of IR spectroscopy. Destruction cross sections, radiolysis yields, and half-life doses were determined for samples at 20, 40, 90, and 300 K. The thickness of the irradiated samples was kept below the estimated penetration depth of the electrons. No significant differences were obtained in the experiments below 90 K, but the destruction cross section at 300 K was larger by a factor of 2. The radiolysis yields and half-life doses are in good accordance with recent MeV proton experiments, which confirms that electrons in the keV range can be used to simulate the effects of cosmic rays if the whole sample is effectively irradiated. In the low temperature experiments, electron irradiation leads to the formation of residues. IR absorptions of these residues are assigned to the presence CO{sub 2}, CO, OCN{sup −}, and CN{sup −} and possibly to amide bands I to III. The protection of glycine by water ice is also studied. A water ice film of ∼150 nm is found to provide efficient shielding against the bombardment of 2 keV electrons. The results of this study show also that current Monte Carlo predictions provide a good global description of electron penetration depths. The lifetimes estimated in this work for various environments ranging from the diffuse interstellar medium to the inner solar system, show that the survival of hypothetical primeval glycine from the solar nebula in present solar system bodies is not very likely.

  10. Ion focusing

    Energy Technology Data Exchange (ETDEWEB)

    Cooks, Robert Graham; Baird, Zane; Peng, Wen-Ping

    2017-01-17

    The invention generally relates to apparatuses for focusing ions at or above ambient pressure and methods of use thereof. In certain embodiments, the invention provides an apparatus for focusing ions that includes an electrode having a cavity, at least one inlet within the electrode configured to operatively couple with an ionization source, such that discharge generated by the ionization source is injected into the cavity of the electrode, and an outlet. The cavity in the electrode is shaped such that upon application of voltage to the electrode, ions within the cavity are focused and directed to the outlet, which is positioned such that a proximal end of the outlet receives the focused ions and a distal end of the outlet is open to ambient pressure.

  11. Temperature-dependent void formation and growth at ion-irradiated nanocrystalline CeO2 Si interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Bergquist, Alex G [ORNL; Zhang, Yanwen [ORNL; Varga, Tamas [Pacific Northwest National Laboratory (PNNL); Moll, Sandra [TN International / AREVA, 1, rue des Hérons, 78182 Montigny Le Bretonneux, France; Namavar, Fereydoon [University of Nebraska Medical Center; Weber, William J [ORNL

    2014-01-01

    Ceria is a thermally stable ceramic that has numerous applications in the nuclear industry, including use in nuclear fuels and waste forms. Recently, interest has surged in nanostructured ceria due to its increased mechanical properties and electronic conductivity in comparison with bulk ceria and its ability to self-heal in response to energetic ion bombardment. Here, nanocrystalline ceria thin films grown over a silicon substrate are irradiated to fluences of up to 4 1016 ions/cm2 under different irradiation conditions: with differing ion species (Si+ and Ni+), different ion energies (1.0 1.5 MeV), and at varying temperatures (160 600 K). While the nanocrystalline ceria is found to exhibit exceptional radiation resistance under all tested conditions, severe ion irradiation-induced mixing, void formation, and void growth are observed at the ceria/silicon interface, with the degree of damage proving to be temperature dependent.

  12. 39Ar-40Ar Dating of Eucrites and Howardites and the Early Bombardment of the HED Parent Body

    Science.gov (United States)

    Bogard, D. D.; Garrison, D. H.

    1993-07-01

    Eucrite and howardite meteorites are impact breccias from the HED parent body, which may have been the 520 km diameter asteroid 4 Vesta [1]. Using textural and compositional information on pyroxenes from individual clasts, [2] proposed a classification scheme based on the degree of thermal metamorphism exhibited by nearly all eucrites. In the highest grade, chemical zoning of pyroxenes has been erased and areas of impact melt sometimes have been produced. Thus, HED meteorites appear to be products of an early bombardment history of the inner portion of the main asteroid belt, just as most lunar highland rocks are products of early impact bombardment of the Moon. To determine the time period for major impacts on the HED parent body, we have measured ^39Ar-^40Ar ages for a large number of eucritic clasts from eucrites and howardites. All of these samples indicate partial to complete K-Ar chronometer resetting by several different impact events much more recent than eucrite crystallization times of ~4.45-4.55 Ga. For example, the ^39Ar- ^40Ar ages of paired eucrites Y-791186 and Y-792510 were essentially entirely reset 3.45 +- 0.05 Ga ago. A clast from Millbillillie gave a slightly older ^39Ar-^40Ar resetting age of 3.55 +- 0.02 Ga. (A similar degassing age of 3.5 +- 0.1 Ga was recently reported for Stannern [3]). Clast EET87531,21 gave a degassing age of 3.83 +- 0.05 Ga; clast EET82600 suggests an age of 3.89 +- 0.07 Ga; a clast from LEW85300 suggests a similar age to these. Several eucritic clasts gave ^39Ar-^40Ar degassing ages near 4.0 Ga. These include two clasts from EET87509 (,71 at 4.00 +- 0.05 Ga and ,74 at 3.93 +- 0.06 Ga), EET87509,24 (4.07 +- 0.02 Ga), Y-792769,68 (3.99 +- 0.04 Ga), and Y-790020,5 (4.03 +- 0.03 Ga). Clast and matrix samples from Y-75011 gave slightly different ages of 3.98 +- 0.03 Ga and 3.94 +- 0.04 Ga. Analyses of several additional eucritic clasts gave less well-defined ^39Ar-^40Ar release spectra that are consistent with this range in

  13. Hydrogenated amorphous silicon p-i-n solar cells deposited under well controlled ion bombardment using pulse-shaped substrate biasing

    NARCIS (Netherlands)

    Wank, M. A.; van Swaaij, R.; R. van de Sanden,; Zeman, M.

    2012-01-01

    We applied pulse-shaped biasing (PSB) to the expanding thermal plasma deposition of intrinsic hydrogenated amorphous silicon layers at substrate temperatures of 200 degrees C and growth rates of about 1?nm/s. Fourier transform infrared spectroscopy of intrinsic films showed a densification with incr

  14. Cubic nitrides of the sixth group of transition metals formed by nitrogen ion irradiation during metal condensation

    Energy Technology Data Exchange (ETDEWEB)

    Ensinger, W. [Augsburg Univ. (Germany). Inst. fuer Physik; Kiuchi, M. [Osaka National Research Institute, Midorigaoka 1-8-31, Ikeda, Osaka 563 (Japan)

    1996-10-01

    Nitrogen-containing phases of chromium, molybdenum and tungsten were formed by evaporation of the metal under simultaneous nitrogen ion irradiation. With gradually increasing ion irradiation intensity, chromium forms initially Cr and Cr{sub 2}N phase mixtures, then additionally CrN appears, and at the highest intensities pure CrN films are formed. Molybdenum also forms pure nitride MoN under intense ion bombardment. However, in this case two different crystal structures are found, the stable hexagonal phase and the metastable cubic high-temperature phase. The latter is favoured under intense ion irradiation. In the case of tungsten, even at the highest intensities, only phase mixtures of W and W{sub 2}N were formed. These observed differences can be explained by the low reactivity of these metals towards nitrogen and the low chemical stability of the nitrides, particularly of WN. The metastable high-temperature structure of MoN is formed under the particular conditions of ion bombardment with rapid energy dissipation. (orig.)

  15. Modification of plasma polymer films by ion implantation

    Directory of Open Access Journals (Sweden)

    Santos Deborah Cristina Ribeiro dos

    2004-01-01

    Full Text Available In this work, thin polymer films were prepared from acetylene and argon radiofrequency (13.56 MHz, 80 W glow discharges. Post-deposition treatment was performed by plasma immersion ion implantation in nitrogen or helium glow discharges (13.56 MHz, 70 W. In these cases, samples were biased with 25 kV negative pulses. Exposure time to the bombardment plasma, t, ranged from 900 to 7200 s. Chemical composition of the film surfaces was investigated by X-ray Photoelectron Spectroscopy and the resistance to oxidation by the etching process, in reactive oxygen plasmas. Oxygen and nitrogen were detected in all the samples. While the concentration of the former continuously changed with t, that of N kept practically constant in small proportions. The film is predominantly formed by sp² states, but the proportion of sp³ hybridization slightly increased with t. The etching rate dropped under certain conditions of nitrogen bombardment whereas helium implantation has not significantly improved it. These results are ascribed to the crosslinking degree of the polymeric chains, ruled by the total amount of energy delivered to the film.

  16. Internal conversion in highly-stripped {sup 83}Kr ions

    Energy Technology Data Exchange (ETDEWEB)

    Rehm, K.E.; Ahmad, I.; Gehring, J. [and others

    1995-08-01

    The transition probability per unit time for the decay of a nuclear level via internal conversion (IC), {lambda}IC, depends on the electron environment of the nucleus. For example, inner-shell conversion in highly-charged ions can change appreciably as electrons are successively removed from the ion. Magnetic dipole (Ml) transitions are especially sensitive to this effect since the internal conversion depends strongly on the electron density at the nucleus. Hence, measurements of {lambda}IC,q, the internal conversion rate in an ion with charge state q, can provide good tests of theoretical electron wave functions if the electron configuration in the ions is known. In a previous experiment, a new method which identifies charge-changing events during passage of ion beams through a magnetic spectrometer was used to determine {lambda}IC,q for the 14.4-keV isomer in {sup 57}Fe. This contribution reports measurements made using the same technique for the 9.4-keV isomer in {sup 83}Kr. A beam of {sup 83}Kr with energy 650 MeV bombarded a Au target with a thickness 300 {mu}g cm{sup -2}. Secondary scattered beams were accepted and analyzed by an Enge magnetic spectrometer. The numbers of excited nuclei decaying during passage through the spectrometer and their internal conversion rates were deduced from the pattern of events measured in the spectrometer focal plane.

  17. Final Report: Mechanisms of sputter ripple formation: coupling among energetic ions, surface kinetics, stress and composition

    Energy Technology Data Exchange (ETDEWEB)

    Chason, Eric; Shenoy, Vivek

    2013-01-22

    Self-organized pattern formation enables the creation of nanoscale surface structures over large areas based on fundamental physical processes rather than an applied template. Low energy ion bombardment is one such method that induces the spontaneous formation of a wide variety of interesting morphological features (e.g., sputter ripples and/or quantum dots). This program focused on the processes controlling sputter ripple formation and the kinetics controlling the evolution of surfaces and nanostructures in high flux environments. This was done by using systematic, quantitative experiments to measure ripple formation under a variety of processing conditions coupled with modeling to interpret the results.

  18. Simple estimates of excitation energy sharing between heavy and light fragments in heavy-ion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Dasso, C.H.; Lozano, M.; Pollarolo, G.

    1985-12-01

    Qualitative arguments are used to estiamte the ratio of excitation energies between heavy and light fragments for asymmetric heavy-ion collisions. The value of this quantity is linked to the relative role played by inelastic and transfer degrees of freedom and thereby to an approximate function of the total kinetic energy loss. A numerical analysis that confirms the trends anticipated by the simple arguments is performed for the reactions /sup 56/Fe+ /sup 238/U and /sup 86/Kr+ /sup 208/Pb at bombarding energies in the laboratory of 476 and 1565 MeV, respectively.

  19. Spatial distribution of particles sputtered from single crystals by gas cluster ions

    Science.gov (United States)

    Nazarov, A. V.; Chernysh, V. S.; Nordlund, K.; Djurabekova, F.; Zhao, J.

    2017-09-01

    The results of molecular dynamics simulations of the bombardment of the Cu (100) and Mo (100) single-crystals by 10 keV Ar cluster ions of different sizes are presented in this paper. Spatial distributions of sputtered material were calculated. The anisotropy of the angular distributions of sputtered atoms was revealed. It was found that the character of the anisotropy is different for Cu and Mo targets. The reasons leading to this anisotropy are discussed according to the dependences of the angular distributions on the cluster size and on the target material.

  20. Bioastrophysical Aspects of Low Energy Ion Irradiation of Frozen Anthracene Containing Water

    Energy Technology Data Exchange (ETDEWEB)

    Tuleta, M.; Gabla, L.; Madej, J.

    2001-08-13

    The origin of life on Earth remains a fascinating mystery in spite of many theories existing on this subject. However, it seems that simple prebiotic molecules could play an essential role in the formation of more complex organisms. In our experiment, we synthesized a class of these molecules (quinones) bombarding frozen anthracene containing water with low energy hydrogen ions. This experiment roughly simulated the astrophysical conditions which one can find in the solar system. Thus, we can hypothesize that prebiotic molecules could be created by interaction of the solar wind with interplanetary dust grains. The delivery of these molecules to early Earth may have contributed to the generation of life on our planet.

  1. Covalent carbon nitride films synthesized by ablated graphite plasma under ion beam co-processing

    Energy Technology Data Exchange (ETDEWEB)

    Zhong-Min Ren; Yuan-Cheng Du; Zhi-Feng Ying [Fudan Univ., Shanghai (China)] [and others

    1995-12-31

    Carbon nitride thin films, with N-concentration about 41% have been synthesized by pulsed laser ablation of graphite under a low-energy nitrogen ion beam bombardment. Electron diffraction and X-ray photoelectron spectra measurements have shown the existence of polycrystallite covalent beta-C{sub 3}N{sub 4} structure in the films. During the syntheses, YAG laser ablation was used with different laser wavelengths: 355, 532 nm and 1,06 {mu}m individually. The analyses of the optical emission spectra (OES) of the ablated plasma indicated that the use of 532 nm laser is more proposed for the purpose of synthesis of good carbon nitride films.

  2. Calculation for fission decay from heavy ion reactions at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Blaich, T.; Begemann-Blaich, M.; Fowler, M.M.; Wilhelmy, J.B. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Britt, H.C.; Fields, D.J.; Hansen, L.F.; Namboodiri, M.N.; Sangster, T.C. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)); Fraenkel, Z. (Weizmann Institute of Science, 76100 Rehovot (Israel))

    1992-02-01

    A detailed deexcitation calculation is presented for target residues resulting from intermediate-energy heavy ion reactions. The model involves an intranuclear cascade, subsequent fast nucleon emission, and final decay by statistical evaporation including fission. Results are compared to data from bombardments with Fe and Nb projectiles on targets of Ta, Au, and Th at 100 MeV/nucleon. The majority of observable features are reproduced with this simple approach, making obvious the need for involving new physical phenomena associated with multifragmentation or other collective dissipation mechanisms.

  3. Molecular depth profiling with cluster secondary ion mass spectrometry and wedges.

    Science.gov (United States)

    Mao, Dan; Wucher, Andreas; Winograd, Nicholas

    2010-01-01

    Secondary ion mass spectrometry and atomic force microscopy are employed to characterize a wedge-shaped crater eroded by 40 keV C(60)(+) bombardment of a 395 nm thin film of Irganox 1010 doped with four delta layers of Irganox 3114. The wedge structure creates a laterally magnified cross section of the film. From an examination of the resulting surface, information about depth resolution, topography, and erosion rate can be obtained as a function of crater depth in a single experiment. This protocol provides a straightforward way to determine the parameters necessary to characterize molecular depth profiles and to obtain an accurate depth scale for erosion experiments.

  4. Study on structural recovery of graphite irradiated with swift heavy ions at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Pellemoine, F., E-mail: pellemoi@frib.msu.edu [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Avilov, M. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Bender, M. [Dept. of Materials Research, GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, Darmstadt 64291 (Germany); Ewing, R.C. [Dept. of Geological Sciences, Stanford University, Stanford, CA 94305-2115 (United States); Fernandes, S. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Lang, M. [Dept. of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996-2300 (United States); Li, W.X. [Dept. of Geological Sciences, Stanford University, Stanford, CA 94305-2115 (United States); Mittig, W. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States); Schein, M. [Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824 (United States); Severin, D. [Dept. of Materials Research, GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, Darmstadt 64291 (Germany); Tomut, M. [Dept. of Materials Research, GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, Darmstadt 64291 (Germany); Laboratory of Magnetism and Superconductivity, National Institute for Materials Physics NIMP, Bucharest (Romania); Trautmann, C. [Dept. of Materials Research, GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, Darmstadt 64291 (Germany); Dept. of Materials Science, Technische Universität Darmstadt, Darmstadt (Germany); and others

    2015-12-15

    Thin graphite foils bombarded with an intense high-energy (8.6 MeV/u) gold beam reaching fluences up to 1 × 10{sup 15} ions/cm{sup 2} lead to swelling and electrical resistivity changes. As shown earlier, these effects are diminished with increasing irradiation temperature. The work reported here extends the investigation of beam induced changes of these samples by structural analysis using synchrotron X-ray diffraction and transmission electron microscope. A nearly complete recovery from swelling at irradiation temperatures above about 1500 °C is identified.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-12-31

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

  6. Fractal characterization of the silicon surfaces produced by ion beam irradiation of varying fluences

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, R.P. [Department of Physics, University of Allahabad, Allahabad, UP 211002 (India); Kumar, T. [Department of Physics, Central University of Haryana, Jant-Pali, Mahendergarh, Haryana 123029 (India); Mittal, A.K. [Department of Physics, University of Allahabad, Allahabad, UP 211002 (India); K Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Allahabad, UP 211002 (India); Dwivedi, S., E-mail: suneetdwivedi@gmail.com [K Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Allahabad, UP 211002 (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, PO Box 10502, New Delhi 110 067 (India)

    2015-08-30

    Highlights: • Fractal analysis of Si(1 0 0) surface morphology at varying ion fluences. • Autocorrelation function and height–height correlation function as fractal measures. • Surface roughness and lateral correlation length increases with ion fluence. • Ripple pattern of the surfaces is found at higher ion fluences. • Wavelength of the ripple surfaces is computed for each fluence. - Abstract: Si (1 0 0) is bombarded with 200 keV Ar{sup +} ion beam at oblique incidence with fluences ranging from 3 × 10{sup 17} ions/cm{sup 2} to 3 × 10{sup 18} ions/cm{sup 2}. The surface morphology of the irradiated surfaces is captured by the atomic force microscopy (AFM) for each ion fluence. The fractal analysis is performed on the AFM images. The autocorrelation function and height–height correlation function are used as fractal measures. It is found that the average roughness, interface width, lateral correlation length as well as roughness exponent increase with ions fluence. The analysis reveals the ripple pattern of the surfaces at higher fluences. The wavelength of the ripple surfaces is computed for each ion fluence.

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

    Science.gov (United States)

    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.

  8. The influence of assisting ion elements on texture improvement of IBAD-Gd{sub 2}Zr{sub 2}O{sub 7} films

    Energy Technology Data Exchange (ETDEWEB)

    Iijima, Yasuhiro [Fujikura Ltd., 1-5-1, Kiba, Koto-ku, Tokyo 135-8512 (Japan)]. E-mail: ijm@rd.fujikura.co.jp; Kaneko, Naoki [Fujikura Ltd., 1-5-1, Kiba, Koto-ku, Tokyo 135-8512 (Japan); Sutoh, Yasunori [Fujikura Ltd., 1-5-1, Kiba, Koto-ku, Tokyo 135-8512 (Japan); Kakimoto, Kazuomi [Fujikura Ltd., 1-5-1, Kiba, Koto-ku, Tokyo 135-8512 (Japan); Saitoh, Takashi [Fujikura Ltd., 1-5-1, Kiba, Koto-ku, Tokyo 135-8512 (Japan); Kato, Takeharu [Fine ceramics center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Hirayama, Tsukasa [Fine ceramics center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan)

    2005-10-01

    The texture evolution property of Gd{sub 2}Zr{sub 2}O{sub 7} (GZO) template films on non-textured Ni-based alloy was studied by off-normal ion-beam-assisted deposition (IBAD) at low temperature of 200 deg. C, with varied bombarding ion elements of Ar, Ne, and O. In all cases a <1 1 1> axis aligned toward the ion incident direction preserving out-of-plane (1 0 0) alignment. The in-plane mosaic spread ({delta}{phi}) were clearly deteriorated for GZO films formed with assisting ions of Ar + Ne mixture or pure oxygen, compared to the case for pure Ar ion assisting. On the other hand, no recognizable ion elemental dependence on {delta}{phi} was observed when GZO films were homoepitaxially grown by IBAD on already textured GZO surface.

  9. Det venskabelige bombardement

    DEFF Research Database (Denmark)

    -norske monarkis magt og velstand. Syv år senere gik Norge tabt. Danmark var blevet "et lidet, fattigt land". Briterne var i krig med franskmændene og ville forhindre dem i at få den danske flåde. Militært var aktionen en succes - det måtte selv Napoleon indrømme. Men den udløste en voldsom debat om mål og midler...

  10. Short-range ordering of ion-implanted nitrogen atoms in SiC-graphene

    Energy Technology Data Exchange (ETDEWEB)

    Willke, P.; Druga, T.; Wenderoth, M. [IV. Physikalisches Institut der Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Amani, J. A.; Weikert, S.; Hofsäss, H. [II. Physikalisches Institut der Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Thakur, S.; Maiti, K. [Department of Condensed Matter Physics and Materials' Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India)

    2014-09-15

    We perform a structural analysis of nitrogen-doped graphene on SiC(0001) prepared by ultra low-energy ion bombardment. Using scanning tunneling microscopy, we show that nitrogen atoms are incorporated almost exclusively as graphitic substitution in the graphene honeycomb lattice. With an irradiation energy of 25 eV and a fluence of approximately 5 × 10{sup 14 }cm{sup −2}, we achieve a nitrogen content of around 1%. By quantitatively comparing the position of the N-atoms in the topography measurements with simulated random distributions, we find statistically significant short-range correlations. Consequently, we are able to show that the dopants arrange preferably at lattice sites given by the 6 × 6-reconstruction of the underlying substrate. This selective incorporation is most likely triggered by adsorbate layers present during the ion bombardment. This study identifies low-energy ion irradiation as a promising method for controlled doping in epitaxial graphene.

  11. New insights from old spherules: Os-W isotope and HSE evidence for Paleoarchean meteorite bombardment of the Earth

    Science.gov (United States)

    Schulz, T.; Luguet, A. A.; Koeberl, C.

    2014-12-01

    Introduction: Although still debated, spherule beds in the Barberton Mountain Land (~3.4 Ga) are suspected to represent remnants of impact-generated and ballistically emplaced silicate melt droplets [e.g. 1]. Such deposits provide the only window into the late stages of the heavy meteorite bombardment on Earth as their source craters have long since been obliterated. In order to identify a possible meteoritic component and, if successful, to discuss potential projectile materials, we are performing a detailed Os-W isotope as well as HSE abundance study on spherule layers from the recently drilled ICDP BARB5 core (grid location 25°30`50.76``S, 31°33`10.08``E). Samples and Methods: Samples were taken from a spherule-containing meta-sedimentary core section discovered between 510 and 512 m depth. About 100 mg of homogenized sample powders were spiked with a mixed 190Os, 185Re, 191Ir and 194Pt tracer and treated in a high pressure asher using inverse aqua regia, followed by conventional extraction schemes for Os and the other HSEs [4]. Chemical and Os isotope measurements (via N-TIMS) were performed in Vienna, whereas HSE measurements were undertaken via ICP MS in Bonn. Results and Discussion: Our preliminary Os isotope data reveal a trend between samples exhibiting high spherule to matrix ratios (187Os/188Os ~0.106 and Os ~0.4 ppm) and samples with lower ones (187Os/188Os up to ~0.304 and Os ~0.008 ppm). Notably, the most unradiogenic samples exhibit carbonaceous-chondrite-like initial 187Os/188Os and HSE ratios, whereas all other samples are clear non-chondritic. These findings support an extraterrestrial contribution in the spherules and can be interpreted compared to conclusions drawn from a Cr isotope study performed on similar samples [3], possibly representing a different impact event and favouring a chondritic projectile. However, further considerations based on precise Os/W ratio determinations and high-precision 182W isotope data, will be presented at the

  12. Calculation of the heat deposition and temperature distribution of the target bombarded by high-energy protons using Monte Carlo simulation and finite element method

    Institute of Scientific and Technical Information of China (English)

    殷雯; 张国锋; 杜建红; 梁九卿

    2003-01-01

    The Monte Carlo simulation and the finite element methods have been used to calculate the heat deposition and temperature distribution in tungsten plate target when the target is bombarded by high-energy protons from the accelerator with nuclear power of 100 kW. The results show that the heat deposition in the target, reflector and shield will be 48 kW, 15 kW and 11 kW, respectively, and the highest temperature in the target plates will be lower than 100 ℃when the surfaces of plates are cooled by water.

  13. Low-energy ion beam-based deposition of gallium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez, M. R., E-mail: mrvasquez@coe.upd.edu.ph [Department of Mining, Metallurgical, and Materials Engineering, College of Engineering, University of the Philippines, Diliman, Quezon City 1101 (Philippines); Wada, M. [Graduate School of Science and Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan)

    2016-02-15

    An ion source with a remote plasma chamber excited by a 13.56 MHz radio frequency power was used for low-energy broad ion beam extraction. Optical emission spectral analyses showed the sputtering and postionization of a liquid gallium (Ga) target placed in a chamber separated from the source bombarded by argon (Ar) plasma guided by a bent magnetic field. In addition, an E × B probe successfully showed the extraction of low-energy Ga and Ar ion beams using a dual-electrode extractor configuration. By introducing dilute amounts of nitrogen gas into the system, formation of thin Ga-based films on a silicon substrate was demonstrated as determined from X-ray diffraction and X-ray reflectivity studies.

  14. Silicon etch with chromium ions generated by a filtered or non-filtered cathodic arc discharge.

    Science.gov (United States)

    Scopece, Daniele; Döbeli, Max; Passerone, Daniele; Maeder, Xavier; Neels, Antonia; Widrig, Beno; Dommann, Alex; Müller, Ulrich; Ramm, Jürgen

    2016-01-01

    The pre-treatment of substrate surfaces prior to deposition is important for the adhesion of physical vapour deposition coatings. This work investigates Si surfaces after the bombardment by energetic Cr ions which are created in cathodic arc discharges. The effect of the pre-treatment is analysed by X-ray diffraction, Rutherford backscattering spectroscopy, scanning electron microscopy and in-depth X-ray photoemission spectroscopy and compared for Cr vapour produced from a filtered and non-filtered cathodic arc discharge. Cr coverage as a function of ion energy was also predicted by TRIDYN Monte Carlo calculations. Discrepancies between measured and simulated values in the transition regime between layer growth and surface removal can be explained by the chemical reactions between Cr ions and the Si substrate or between the substrate surface and the residual gases. Simulations help to find optimum and more stable parameters for specific film and substrate combinations faster than trial-and-error procedure.

  15. Low-energy ion beam-based deposition of gallium nitride.

    Science.gov (United States)

    Vasquez, M R; Wada, M

    2016-02-01

    An ion source with a remote plasma chamber excited by a 13.56 MHz radio frequency power was used for low-energy broad ion beam extraction. Optical emission spectral analyses showed the sputtering and postionization of a liquid gallium (Ga) target placed in a chamber separated from the source bombarded by argon (Ar) plasma guided by a bent magnetic field. In addition, an E × B probe successfully showed the extraction of low-energy Ga and Ar ion beams using a dual-electrode extractor configuration. By introducing dilute amounts of nitrogen gas into the system, formation of thin Ga-based films on a silicon substrate was demonstrated as determined from X-ray diffraction and X-ray reflectivity studies.

  16. Role of substrate morphology in ion induced dewetting of thin solid films

    Energy Technology Data Exchange (ETDEWEB)

    Repetto, Luca, E-mail: luca.repetto@unige.it [Physics Department and Nanomed Labs, Università di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Lo Savio, Roberto [Physics Department and Nanomed Labs, Università di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Šetina Batič, Barbara [Inštitut Za Kovinske Materiale in Tehnologije, Lepi pot 11, 1000 Ljubljana (Slovenia); Firpo, Giuseppe; Valbusa, Ugo [Physics Department and Nanomed Labs, Università di Genova, Via Dodecaneso 33, 16146 Genova (Italy)

    2014-10-01

    Highlights: • We have created by ion bombardment silicon substrates with different topographies. • The substrates have been characterized by ellipsometry, AFM, SEM and EDX. • The substrates have been used for experiments of ion induced Cr films. • We show that different substrate topographies can induce different dewetted patterns. • Substrate topography can favor spinodal dewetting against heterogeneous nucleations. - Abstract: We investigate the role of the substrate morphology in the dewetting of ultrathin chromium films irradiated with 30 keV Ga ions. Silicon surfaces with different roughness were used as substrates for the films. The results of the irradiation experiments and of related simulations indicate that the chromium films can undergo a dewetting-like process through the two standard channels that show up for liquids, namely the spinodal channel, and the dewetting by heterogeneous nucleation. The two processes are competitive, and the prevailing one can be predicted and selected according to the characteristics of the substrate.

  17. Development of vertical compact ion implanter for gemstones applications

    Energy Technology Data Exchange (ETDEWEB)

    Intarasiri, S., E-mail: saweat@gmail.com [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Wijaikhum, A. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Bootkul, D., E-mail: mo_duangkhae@hotmail.com [Department of General Science (Gems and Jewelry), Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Suwannakachorn, D.; Tippawan, U.; Yu, L.D.; Singkarat, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2014-08-15

    Ion implantation technique was applied as an effective non-toxic treatment of the local Thai natural corundum including sapphires and rubies for the enhancement of essential qualities of the gemstones. Energetic oxygen and nitrogen ions in keV range of various fluences were implanted into the precious stones. It has been thoroughly proved that ion implantation can definitely modify the gems to desirable colors together with changing their color distribution, transparency and luster properties. These modifications lead to the improvement in quality of the natural corundum and thus its market value. Possible mechanisms of these modifications have been proposed. The main causes could be the changes in oxidation states of impurities of transition metals, induction of charge transfer from one metal cation to another and the production of color centers. For these purposes, an ion implanter of the kind that is traditionally used in semiconductor wafer fabrication had already been successfully applied for the ion beam bombardment of natural corundum. However, it is not practical for implanting the irregular shape and size of gem samples, and too costly to be economically accepted by the gem and jewelry industry. Accordingly, a specialized ion implanter has been requested by the gem traders. We have succeeded in developing a prototype high-current vertical compact ion implanter only 1.36 m long, from ion source to irradiation chamber, for these purposes. It has been proved to be very effective for corundum, for example, color improvement of blue sapphire, induction of violet sapphire from low value pink sapphire, and amelioration of lead-glass-filled rubies. Details of the implanter and recent implantation results are presented.

  18. Development of vertical compact ion implanter for gemstones applications

    Science.gov (United States)

    Intarasiri, S.; Wijaikhum, A.; Bootkul, D.; Suwannakachorn, D.; Tippawan, U.; Yu, L. D.; Singkarat, S.

    2014-08-01

    Ion implantation technique was applied as an effective non-toxic treatment of the local Thai natural corundum including sapphires and rubies for the enhancement of essential qualities of the gemstones. Energetic oxygen and nitrogen ions in keV range of various fluences were implanted into the precious stones. It has been thoroughly proved that ion implantation can definitely modify the gems to desirable colors together with changing their color distribution, transparency and luster properties. These modifications lead to the improvement in quality of the natural corundum and thus its market value. Possible mechanisms of these modifications have been proposed. The main causes could be the changes in oxidation states of impurities of transition metals, induction of charge transfer from one metal cation to another and the production of color centers. For these purposes, an ion implanter of the kind that is traditionally used in semiconductor wafer fabrication had already been successfully applied for the ion beam bombardment of natural corundum. However, it is not practical for implanting the irregular shape and size of gem samples, and too costly to be economically accepted by the gem and jewelry industry. Accordingly, a specialized ion implanter has been requested by the gem traders. We have succeeded in developing a prototype high-current vertical compact ion implanter only 1.36 m long, from ion source to irradiation chamber, for these purposes. It has been proved to be very effective for corundum, for example, color improvement of blue sapphire, induction of violet sapphire from low value pink sapphire, and amelioration of lead-glass-filled rubies. Details of the implanter and recent implantation results are presented.

  19. Preliminary Research Results for the Generation and Diagnostics of High Power Ion Beams on FLASH II Accelerator

    Science.gov (United States)

    Yang, Hailiang; Qiu, Aici; Sun, Jianfeng; He, Xiaoping; Tang, Junping; Wang, Haiyang; Li, Hongyu; Li, Jingya; Ren, Shuqing; Ouyang, Xiaoping; Zhang, Guoguang

    2004-12-01

    The preliminary experimental results of the generation and diagnostics of high-power ion beams of FLASH II accelerator are reported. The high-power ion beams presently are being produced in a pinched diode. The method for enhancing the ratio of ion to electron current is to increase the electron residing time by pinching the electron flow. Furthermore, electron beam pinching can be combined with electron reflexing to achieve ion beams with even higher efficiency and intensity. The anode plasma is generated by anode foil bombarded with electron and anode foil surface flashover. In recent experiments on FLASH II accelerator, ion beams have been produced with a current of 160 kA and an energy of 500 keV corresponding to an ion beam peak power of about 80 GW. The ion number and current of high power ion beams were determined by monitoring delayed radioactivity from nuclear reactions induced in a 12C target by the proton beams. The prompt γ-rays and diode bremsstrahlung x-rays were measured with a PIN semi-conductor detector and a plastic scintillator detector. The current density distribution of ion beam were measured with a biased ion collector array. The ion beams were also recorded with a CR-39 detector.

  20. Preliminary Research Results for the Generation and Diagnostics of High Power Ion Beams on FLASH II Accelerator

    Institute of Scientific and Technical Information of China (English)

    杨海亮; 邱爱慈; 孙剑锋; 何小平; 汤俊萍; 王海洋; 李洪玉; 李静雅; 任书庆; 欧阳小平; 张国光

    2004-01-01

    The preliminary experimental results of the generation and diagnostics of high power ion beams on FLASH II accelerator are reported. The high-power ion beams presently are being produced in a pinched diode. The method for enhancing the ratio of ion to electron current is to increase the electron residing time by pinching the electron flow. Furthermore, electron beam pinching can be combined with electron reflexing to achieve ion beams with even higher efficiency and intensity. The anode plasma is generated by anode foil bombarded with electronand anode foil surface flashover. In recent experiments on FLASH II accelerator, ion beams have been produced with a current of 160 kA and anen ergy of 500 keV corresponding to an ion beam peak power of about 80 GW. The ion number ard current of high power ion beams were determined by monitoring delayed radioactivity from nuclear reactions induced in a 12C target by the proton beams. The prompt γ-rays and diode bremsstrahlung X-rays were measured with a PIN semi-conductor detector and a plastic scintillator detector. The current density distribution of ion beam were measured with a biased ion collector array. The ion beams were also recorded with a CR-39 detector.

  1. Development of a fast atom bombardment tandem mass spectrometric screening method for alkyl-ended oligomeric biguanides

    Science.gov (United States)

    Monaghan, J. J.; Morden, W. E.

    1992-12-01

    The FAB-MS and FAB-MS---MS behaviour of a series of "alkyl-ended" oligomeric biguanides has been studied. MS---MS product ion scans showed that fragmentation of these species occurred by predictable cleavages of the biguanide chains. Results are presented from a number of MS---MS precursor ion and neutral loss scans studied in an attempt to develop a screening method for biguanides in complex mixtures. The most effective of these scans is shown to be the neutral loss of the N-alkylguanidine molecule. Use of this scan is demonstrated for a mixture of oligomeric biguanides.

  2. Atomic Oxygen (ATOX) simulation of Teflon FEP and Kapton H surfaces using a high intensity, low energy, mass selected, ion beam facility

    Science.gov (United States)

    Vered, R.; Grossman, E.; Lempert, G. D.; Lifshitz, Y.

    1994-01-01

    A high intensity (greater than 10(exp 15) ions/sq cm) low energy (down to 5 eV) mass selected ion beam (MSIB) facility was used to study the effects of ATOX on two polymers commonly used for space applications (Kapton H and Teflon FEP). The polymers were exposed to O(+) and Ne(+) fluences on 10(exp 15) - 10(exp 19) ions/sq cm, using 30eV ions. A variety of analytical methods were used to analyze the eroded surfaces including: (1) atomic force microscopy (AFM) for morphology measurements; (2) total mass loss measurements using a microbalance; (3) surface chemical composition using x-ray photoelectron spectroscopy (XPS), and (4) residual gas analysis (RGA) of the released gases during bombardment. The relative significance of the collisional and chemical degradation processes was evaluated by comparing the effects of Ne(+) and O(+) bombardment. For 30 eV ions it was found that the Kapton is eroded via chemical mechanisms while Teflon FEP is eroded via collisional mechanisms. AFM analysis was found very powerful in revealing the evolution of the damage from its initial atomic scale (roughness of approx. 1 nm) to its final microscopic scale (roughness greater than 1 micron). Both the surface morphology and the average roughness of the bombarded surfaces (averaged over 1 micron x 1 micron images by the system's computer) were determined for each sample. For 30 eV a non linear increase of the Kapton roughness with the O(+) fluence was discovered (a slow increase rate for fluences phi less than 5 x 10(exp 17) O(+)/sq cm, and a rapid increase rate for phi greater than 5 x 10(exp 17) O(+)/sq cm). Comparative studies on the same materials exposed to RF and DC oxygen plasmas indicate that the specific details of the erosion depend on the simulation facility emphasizing the advantages of the ion beam facility.

  3. Note: Ion-induced secondary electron emission from oxidized metal surfaces measured in a particle beam reactor

    Science.gov (United States)

    Marcak, Adrian; Corbella, Carles; de los Arcos, Teresa; von Keudell, Achim

    2015-10-01

    The secondary electron emission of metals induced by slow ions is characterized in a beam chamber by means of two coaxial semi-cylindrical electrodes with different apertures. The voltages of the outer electrode (screening), inner electrode (collector), and sample holder (target) were set independently in order to measure the effective yield of potential and kinetic electron emissions during ion bombardment. Aluminum samples were exposed to quantified beams of argon ions up to 2000 eV and to oxygen atoms and molecules in order to mimic the plasma-surface interactions on metallic targets during reactive sputtering. The variation of electron emission yield was correlated to the ion energy and to the oxidation state of Al surfaces. This system provides reliable measurements of the electron yields in real time and is of great utility to explore the fundamental surface processes during target poisoning occurring in reactive magnetron sputtering applications.

  4. Note: Ion-induced secondary electron emission from oxidized metal surfaces measured in a particle beam reactor

    Energy Technology Data Exchange (ETDEWEB)

    Marcak, Adrian; Corbella, Carles, E-mail: carles.corbella@rub.de; Keudell, Achim von [Research Group Reactive Plasmas, Ruhr-University Bochum, 44801 Bochum (Germany); Arcos, Teresa de los [Technical and Macromolecular Chemistry, Paderborn University, 33098 Paderborn (Germany)

    2015-10-15

    The secondary electron emission of metals induced by slow ions is characterized in a beam chamber by means of two coaxial semi-cylindrical electrodes with different apertures. The voltages of the outer electrode (screening), inner electrode (collector), and sample holder (target) were set independently in order to measure the effective yield of potential and kinetic electron emissions during ion bombardment. Aluminum samples were exposed to quantified beams of argon ions up to 2000 eV and to oxygen atoms and molecules in order to mimic the plasma-surface interactions on metallic targets during reactive sputtering. The variation of electron emission yield was correlated to the ion energy and to the oxidation state of Al surfaces. This system provides reliable measurements of the electron yields in real time and is of great utility to explore the fundamental surface processes during target poisoning occurring in reactive magnetron sputtering applications.

  5. SMILETRAP - A Penning trap facility for precision mass measurements using highly charged ions

    CERN Document Server

    Bergström, I; Fritioff, T; Douysset, G; Schoenfelder, J; Schuch, R

    2002-01-01

    The precision of mass measurements in a Penning trap increases linearly with the charge of the ion. Therefore we have attached a Penning trap, named SMILETRAP, to the electron beam ion source CRYSIS at MSL. CRYSIS is via an isotope separator connected to an ion source that can deliver singly charged ions of practically any element. In CRYSIS charge state breeding occurs by intense electron bombardment. We have shown that it is possible to produce, catch and measure the cyclotron frequencies of ions in the charge region 1+ to 52+. The relevant observable in mass measurements using a Penning trap is the ratio of the cyclotron frequencies of the ion of interest and ion used as a mass reference. High precision requires that the two frequencies are measured after one another in the shortest possible time. For reasons of convenience the precision trap operates at room temperature. So far it has been believed that warm traps working at 4 K are required for high mass precision with exactly one ion in the trap at a ti...

  6. Influence of deposition parameters on the microstructure of ion-plated films

    Science.gov (United States)

    Broitman, Esteban; Zimmerman, Rosa

    1996-07-01

    Ion plating is essentially vapor deposition onto a substrate which is the cathode of a glow discharge. The most important characteristic of the technique is that the growing film is subjected to a flux of high energy particles (neutrals and ions). In this study we report information about the effect of ion plating parameters on grain diameter and crystallite size distribution. At a constant potential grain size remains constant with the increase of ion density. On the other hand, at a constant ion density the grain size decreases with the substrate potential increment. Ion bombardment also has an effect on the crystallite size distribution. The ion plated films show a higher degree of uniformity in grain size than vacuum evaporated films. In contrast with vacuum evaporated films, where the grain size is proportional to the thickness, no variation of grain size with film thickness has been observed for the ion-plated films. Electron diffraction patterns have shown that the orientation remains near random over the entire J and V range studied.

  7. Ion beam modification of polyimide membranes for gas permeation

    Science.gov (United States)

    Escoubes, M.; Dolveck, J. Y.; Davenas, J.; Xu, X. L.; Boiteux, G.

    1995-11-01

    The irradiation of 6FDA (hexafluorodianhydrid) polyimide films, produced for gas separation, with ion beams leads to dramatic modifications of their permeability to hydrogen and methane. The irradiation of the PI membranes with 2 MeV α particles induces a permeability increase for both gases, whereas a reduction of the permeability to CH 4 is obtained for a bombardment of the films with 170 keV N + at fluences larger than 10 15 cm -2. The modification of the diffusion through the membranes has been interpreted using a multilayer model, which enabled the calculation of the intrinsic permeabilities of the irradiated layers. The second irradiation regime induces a significant selectivity enhancement. The improvement of the selective properties of the irradiated membranes is interpreted in terms of modification of the elementary free volumes involving the reduction of the mean size.

  8. Modified {pi}-states in ion-irradiated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Kovach, G. [Research Institute for Technical Physics and Materials Sciences, P.O. Box 49, H-1525 Budapest (Hungary)], E-mail: gkovach@chemres.hu; Karacs, A.; Radnoczi, G.; Csorbai, H. [Research Institute for Technical Physics and Materials Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Guczi, L. [Institute of Isotope, Department of Surface Chemistry and Catalysis, P.O. Box 77, H-1525 Budapest (Hungary); Veres, M.; Koos, M. [Research Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest (Hungary); Papadimitriou, L. [Aristotle University of Thessaloniki, Department of Physics, Solid State Physics Section, 54124 Thessaloniki (Greece); Solyom, A. [Budapest University of Technology and Economics, Department of Atomic Physics, Budafoki ut 8, H-1111 Budapest (Hungary); Peto, G. [Research Institute for Technical Physics and Materials Sciences, P.O. Box 49, H-1525 Budapest (Hungary)

    2008-02-28

    CVD polycrystalline diamond film, pulse laser-deposited (PLD) carbon film and highly oriented pirolitical graphite (HOPG) as reference, were modified by means of Ar{sup +} ion bombardment and characterized by means of Raman scattering, transmission electron microscopy, electron-diffraction (TEM), reflected electron energy loss specroscopy (REELS) and X-ray photoelectron spectroscopy (XPS) techniques. It was found that the diamond was transferred to a carbon with halo-like morphology and disordered stack of graphene segments. Instead of the well-known electron energy loss peak of graphite at 6.5 eV, a new REELS peak appeared at 4-5 eV energies. The observed effect was explained by the modification of {pi}-system in carbon films as a consequence of the formation of non-planar, nanometer-sized graphitic planes.

  9. (Anti-)strangeness production in heavy-ion collisions

    CERN Document Server

    Moreau, Pierre; Ko, Che-Ming; Cassing, Wolfgang; Bratkovskaya, Elena

    2015-01-01

    The production and dynamics of strange and antistrange hadrons in heavy-ion reactions from $\\sqrt{s_{NN}} \\approx$ 3 GeV to 200 GeV is analyzed within the Parton-Hadron-String-Dynamics (PHSD) transport model. The PHSD results for strange baryon and antibaryon production are roughly consistent with the experimental data starting from upper SPS energies. Nevertheless, hadronic final state flavor-exchange reactions are important for the actual abundances, in particular at large rapidities where hadronic dynamics, parton fragmentation and string decay dominate. A striking disagreement between the PHSD results and the available data persists, however, for bombarding energies below $\\sqrt{s_{NN}} \\approx$ 8 GeV where the strangeness production is significantly underestimated as in earlier HSD studies. This finding implies that the strangeness enhancement seen experimentally at FAIR/NICA energies cannot be attributed to a deconfinement phase transition or crossover but probably involves the approximate restoration o...

  10. Ion-Implanted Diamond Films and Their Tribological Properties

    Science.gov (United States)

    Wu, Richard L. C.; Miyoshi, Kazuhisa; Korenyi-Both, Andras L.; Garscadden, Alan; Barnes, Paul N.

    1993-01-01

    This paper reports the physical characterization and tribological evaluation of ion-implanted diamond films. Diamond films were produced by microwave plasma, chemical vapor deposition technique. Diamond films with various grain sizes (0.3 and 3 microns) and roughness (9.1 and 92.1 nm r.m.s. respectively) were implanted with C(+) (m/e = 12) at an ion energy of 160 eV and a fluence of 6.72 x 10(exp 17) ions/sq cm. Unidirectional sliding friction experiments were conducted in ultrahigh vacuum (6.6 x 10(exp -7)Pa), dry nitrogen and humid air (40% RH) environments. The effects of C(+) ion bombardment on fine and coarse-grained diamond films are as follows: the surface morphology of the diamond films did not change; the surface roughness increased (16.3 and 135.3 nm r.m.s.); the diamond structures were damaged and formed a thin layer of amorphous non-diamond carbon; the friction coefficients dramatically decreased in the ultrahigh vacuum (0.1 and 0.4); the friction coefficients decreased slightly in the dry nitrogen and humid air environments.

  11. The Formation of Jupiter, the Jovian Early Bombardment and the Delivery of Water to the Asteroid Belt: The Case of (4) Vesta

    CERN Document Server

    Turrini, Diego

    2014-01-01

    The asteroid (4) Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and...

  12. The formation of jupiter, the jovian early bombardment and the delivery of water to the asteroid belt: the case of (4) vesta.

    Science.gov (United States)

    Turrini, Diego; Svetsov, Vladimir

    2014-01-28

    The asteroid (4) Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and collisional evolution of Vesta. In particular, we argue that the observational data are best reproduced if the bulk of the impactors was represented by 1-2 km wide planetesimals and if Jupiter underwent a limited (a fraction of au) displacement.

  13. The Formation of Jupiter, the Jovian Early Bombardment and the Delivery of Water to the Asteroid Belt: The Case of (4 Vesta

    Directory of Open Access Journals (Sweden)

    Diego Turrini

    2014-01-01

    Full Text Available The asteroid (4 Vesta, parent body of the Howardite-Eucrite-Diogenite meteorites, is one of the first bodies that formed, mostly from volatile-depleted material, in the Solar System. The Dawn mission recently provided evidence that hydrated material was delivered to Vesta, possibly in a continuous way, over the last 4 Ga, while the study of the eucritic meteorites revealed a few samples that crystallized in presence of water and volatile elements. The formation of Jupiter and probably its migration occurred in the period when eucrites crystallized, and triggered a phase of bombardment that caused icy planetesimals to cross the asteroid belt. In this work, we study the flux of icy planetesimals on Vesta during the Jovian Early Bombardment and, using hydrodynamic simulations, the outcome of their collisions with the asteroid. We explore how the migration of the giant planet would affect the delivery of water and volatile materials to the asteroid and we discuss our results in the context of the geophysical and collisional evolution of Vesta. In particular, we argue that the observational data are best reproduced if the bulk of the impactors was represented by 1–2 km wide planetesimals and if Jupiter underwent a limited (a fraction of au displacement.

  14. A simple ion implanter for material modifications in agriculture and gemmology

    Science.gov (United States)

    Singkarat, S.; Wijaikhum, A.; Suwannakachorn, D.; Tippawan, U.; Intarasiri, S.; Bootkul, D.; Phanchaisri, B.; Techarung, J.; Rhodes, M. W.; Suwankosum, R.; Rattanarin, S.; Yu, L. D.

    2015-12-01

    In our efforts in developing ion beam technology for novel applications in biology and gemmology, an economic simple compact ion implanter especially for the purpose was constructed. The designing of the machine was aimed at providing our users with a simple, economic, user friendly, convenient and easily operateable ion implanter for ion implantation of biological living materials and gemstones for biotechnological applications and modification of gemstones, which would eventually contribute to the national agriculture, biomedicine and gem-industry developments. The machine was in a vertical setup so that the samples could be placed horizontally and even without fixing; in a non-mass-analyzing ion implanter style using mixed molecular and atomic nitrogen (N) ions so that material modifications could be more effective; equipped with a focusing/defocusing lens and an X-Y beam scanner so that a broad beam could be possible; and also equipped with a relatively small target chamber so that living biological samples could survive from the vacuum period during ion implantation. To save equipment materials and costs, most of the components of the machine were taken from decommissioned ion beam facilities. The maximum accelerating voltage of the accelerator was 100 kV, ideally necessary for crop mutation induction and gem modification by ion beams from our experience. N-ion implantation of local rice seeds and cut gemstones was carried out. Various phenotype changes of grown rice from the ion-implanted seeds and improvements in gemmological quality of the ion-bombarded gemstones were observed. The success in development of such a low-cost and simple-structured ion implanter provides developing countries with a model of utilizing our limited resources to develop novel accelerator-based technologies and applications.

  15. A simple ion implanter for material modifications in agriculture and gemmology

    Energy Technology Data Exchange (ETDEWEB)

    Singkarat, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Wijaikhum, A. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Suwannakachorn, D.; Tippawan, U. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Intarasiri, S. [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50200 (Thailand); Bootkul, D. [Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Phanchaisri, B.; Techarung, J. [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50200 (Thailand); Rhodes, M.W.; Suwankosum, R.; Rattanarin, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

    2015-12-15

    In our efforts in developing ion beam technology for novel applications in biology and gemmology, an economic simple compact ion implanter especially for the purpose was constructed. The designing of the machine was aimed at providing our users with a simple, economic, user friendly, convenient and easily operateable ion implanter for ion implantation of biological living materials and gemstones for biotechnological applications and modification of gemstones, which would eventually contribute to the national agriculture, biomedicine and gem-industry developments. The machine was in a vertical setup so that the samples could be placed horizontally and even without fixing; in a non-mass-analyzing ion implanter style using mixed molecular and atomic nitrogen (N) ions so that material modifications could be more effective; equipped with a focusing/defocusing lens and an X–Y beam scanner so that a broad beam could be possible; and also equipped with a relatively small target chamber so that living biological samples could survive from the vacuum period during ion implantation. To save equipment materials and costs, most of the components of the machine were taken from decommissioned ion beam facilities. The maximum accelerating voltage of the accelerator was 100 kV, ideally necessary for crop mutation induction and gem modification by ion beams from our experience. N-ion implantation of local rice seeds and cut gemstones was carried out. Various phenotype changes of grown rice from the ion-implanted seeds and improvements in gemmological quality of the ion-bombarded gemstones were observed. The success in development of such a low-cost and simple-structured ion implanter provides developing countries with a model of utilizing our limited resources to develop novel accelerator-based technologies and applications.

  16. ION VATAMANU

    Directory of Open Access Journals (Sweden)

    l. Povar

    2012-12-01

    Full Text Available Ion Vatamanu was a chemist, writer and public figure. He was equally passionate about both his chosen fields of activity: chemistry and poetry. Chemistry, with its perfect equilibrium of logic and precision, provided inspiration for lyrical creativity, whereas poetry writing enlivened his imagination and passion for chemistry. He loved his parents. He adored his wife Elena, whom he often gifted a sea of flowers. He loved his daughters Mihaela, Mariana, and Leontina. He loved life, and he loved people.

  17. Electron Beam Ion Sources

    OpenAIRE

    Zschornacka, G.; Schmidt, M.; Thorn, A.

    2014-01-01

    Electron beam ion sources (EBISs) are ion sources that work based on the principle of electron impact ionization, allowing the production of very highly charged ions. The ions produced can be extracted as a DC ion beam as well as ion pulses of different time structures. In comparison to most of the other known ion sources, EBISs feature ion beams with very good beam emittances and a low energy spread. Furthermore, EBISs are excellent sources of photons (X-rays, ultraviolet, extreme ultraviole...

  18. Ion Beam Extraction by Discrete Ion Focusing

    DEFF Research Database (Denmark)

    2010-01-01

    An apparatus (900) and methods are disclosed for ion beam extraction. In an implementation, the apparatus includes a plasma source (or plasma) (802) and an ion extractor (804). The plasma source is adapted to generate ions and the ion extractor is immersed in the plasma source to extract a fraction...... of the generated ions. The ion extractor is surrounded by a space charge (810) formed at least in part by the extracted ions. The ion extractor includes a biased electrode (806) forming an interface with an insulator (808). The interface is customized to form a strongly curved potential distribution (812......) in the space-charge surrounding the ion extractor. The strongly curved potential distribution focuses the extracted ions towards an opening (814) on a surface of the biased electrode thereby resulting in an ion beam....

  19. Spectral measurements of neutrons, protons, deuterons and tritons produced by 100 MeV/nucleon He bombardment

    CERN Document Server

    Kurosawa, T; Nakao, N; Shibata, T; Uwamino, Y; Fukumura, A

    1999-01-01

    We measured angular and energy distributions of neutrons, protons, deuterons and tritons produced by 100 MeV/nucleon He ions stopping in thick carbon, aluminum, copper and lead targets using the HIMAC (Heavy Ion Medical Accelerator in Chiba) of NIRS (National Institute of Radiological Sciences), Japan by using the time-of-flight method coupled with the DELTA E-E counter system. The DELTA E counter of the NE102A plastic scintillator was used to discriminate charged particles from noncharged particles and to measure charged particle energy spectra. The E counter of the NE213 liquid scintillator was used to measure neutron energy spectra. The experimental spectra were compared with the calculation using the LCS code and the calculated spectra are generally in rather good agreement with the measured spectra of these four secondary particles.

  20. Instrumentation: Ion Chromatography.

    Science.gov (United States)

    Fritz, James S.

    1987-01-01

    Discusses the importance of ion chromatography in separating and measuring anions. The principles of ion exchange are presented, along with some applications of ion chromatography in industry. Ion chromatography systems are described, as well as ion pair and ion exclusion chromatography, column packings, detectors, and programming. (TW)