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Sample records for low-energy nitrogen implantation

  1. Nitrogen mass transfer models for plasma-based low-energy ion implantation

    SciTech Connect

    Zheng, Bocong; Wang, Kesheng; Zhang, Zhipeng; Che, Honglong; Lei, Mingkai

    2015-03-15

    The nitrogen mass transfer process in plasma-based low-energy ion implantation (PBLEII) is theoretically and experimentally studied in order to explore the process mechanism of PBLEII and therefore to optimize the apparatus design and the process conditions. An electron cyclotron resonance (ECR) microwave discharge generates the nitrogen plasma with a high density of 10{sup 11}–10{sup 12} ions/cm{sup 3}, which diffuses downstream to the process chamber along the divergent magnetic field. The nitrogen ions in the plasma implant into the surface and transport to the matrix of an austenitic stainless steel under the low negative pulsed bias of −2 kV at a process temperature of 400 °C. A global plasma model is used to simulate the ECR microwave plasma discharge for a range of working pressures and microwave powers. The fluid models are adopted to calculate the plasma downstream diffusion, the sheath expansion and the low-energy ion implantation on the surface. A nonlinear kinetic discrete model is established to describe the nitrogen transport in the austenitic stainless steel and the results are compared with the experimental measurements. Under an average implantation current density of 0.3–0.6 mA/cm{sup 2}, the surface nitrogen concentration in the range from 18.5 to 29 at. % is a critical factor for the nitrogen transport in the AISI 304 austenitic stainless steel by PBLEII, which accelerates the implanted nitrogen diffusion inward up to 6–12 μm during a nitriding time of 4 h.

  2. Enhanced nitrogen and phosphorus removal from eutrophic lake water by Ipomoea aquatica with low-energy ion implantation.

    PubMed

    Li, Miao; Wu, Yue-Jin; Yu, Zeng-Liang; Sheng, Guo-Ping; Yu, Han-Qing

    2009-03-01

    Ipomoea aquatica with low-energy N+ ion implantation was used for the removal of both nitrogen and phosphorus from the eutrophic Chaohu Lake, China. The biomass growth, nitrate reductase and peroxidase activities of the implanted I. aquatica were found to be higher than those of I. aquatica without ion implantation. Higher NO3-N and PO4-P removal efficiencies were obtained for the I. aquatica irradiation at 25 keV, 3.9 x 10(16) N+ ions/cm(2) and 20 keV 5.2 x 10(16) N+ ions/cm(2), respectively (p < 0.05). Moreover, the nitrogen and phosphorus contents in the plant biomass with ion implantation were also greater than those of the controls. I. aquatica with ion implantation was directly responsible for 51-68% N removal and 54-71% P removal in the three experiments. The results further confirm that the ion implantation could enhance the growth potential of I. aquatica in real eutrophic water and increase its nutrient removal efficiency. Thus, the low-energy ion implantation for aquatic plants could be considered as an approach for in situ phytoremediation and bioremediation of eutrophic waters. PMID:19147171

  3. Biological effects of low energy nitrogen ion implantation on Jatropha curcas L. seed germination

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Wang, Xiao-teng; Gan, Cai-ling; Fang, Yan-qiong; Zhang, Meng

    2012-09-01

    To explore the biological effects of nitrogen ion beam implantation on dry Jatropha curcas seed, a beam of N+ with energy of 25 keV was applied to treat the dry seed at six different doses. N+ beam implantation greatly decreased germination rate and seedling survival rate. The doses within the range of 12 × 1016 to 15 × 1016 ions cm-2 severely damaged the seeds: total antioxidant capacity (TAC), germination rate, seedling survival rate, reduced ascorbate acid (HAsA) and reduced glutathione (GSH) contents, and most of the tested antioxidases activity (i.e. catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD)) reached their lowest levels. At a dose of 18 × 1016 ion cm-2, biological repair took place: moderate increases were found in TAC, germination rate, seedling survival rate, HAsA and GSH contents, and some antioxidant enzyme activities (i.e. CAT, APX, SOD and GPX). The dose of 18 × 1016 ions cm-2 may be the optimum dose for use in dry J. curcas seed mutation breeding. CAT, HAsA and GSH contributed to the increase of TAC, but CAT was the most important. POD performed its important role as seed was severely damaged. The main role of the HAsA-GSH cycle appeared to be for regeneration of HAsA.

  4. Improving low-energy boron/nitrogen ion implantation in graphene by ion bombardment at oblique angles

    NASA Astrophysics Data System (ADS)

    Bai, Zhitong; Zhang, Lin; Liu, Ling

    2016-04-01

    Ion implantation is a widely adopted approach to structurally modify graphene and tune its electrical properties for a variety of applications. Further development of the approach requires a fundamental understanding of the mechanisms that govern the ion bombardment process as well as establishment of key relationships between the controlling parameters and the dominant physics. Here, using molecular dynamics simulations with adaptive bond order calculations, we demonstrate that boron and nitrogen ion bombardment at oblique angles (particularly at 70°) can improve both the productivity and quality of perfect substitution by over 25%. We accomplished this by systematically analyzing the effects of the incident angle and ion energy in determining the probabilities of six distinct types of physics that may occur in an ion bombardment event, including reflection, absorption, substitution, single vacancy, double vacancy, and transmission. By analyzing the atomic trajectories from 576 000 simulations, we identified three single vacancy creation mechanisms and four double vacancy creation mechanisms, and quantified their probability distributions in the angle-energy space. These findings further open the door for improved control of ion implantation towards a wide range of applications of graphene.Ion implantation is a widely adopted approach to structurally modify graphene and tune its electrical properties for a variety of applications. Further development of the approach requires a fundamental understanding of the mechanisms that govern the ion bombardment process as well as establishment of key relationships between the controlling parameters and the dominant physics. Here, using molecular dynamics simulations with adaptive bond order calculations, we demonstrate that boron and nitrogen ion bombardment at oblique angles (particularly at 70°) can improve both the productivity and quality of perfect substitution by over 25%. We accomplished this by systematically

  5. Surface Passivation and Junction Formation Using Low Energy Hydrogen Implants

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.

    1985-01-01

    New applications for high current, low energy hydrogen ion implants on single crystal and polycrystal silicon grain boundaries are discussed. The effects of low energy hydrogen ion beams on crystalline Si surfaces are considered. The effect of these beams on bulk defects in crystalline Si is addressed. Specific applications of H+ implants to crystalline Si processing are discussed. In all of the situations reported on, the hydrogen beams were produced using a high current Kaufman ion source.

  6. Isotopic fractionation in low-energy ion implantation

    NASA Astrophysics Data System (ADS)

    Ponganis, K. V.; Graf, T.; Marti, K.

    1997-08-01

    The evolutions of planetary atmospheres and other solar system reservoirs have been affected by a variety of fractionating mechanisms. It has been suggested that one of these mechanisms could be low-energy ion implantation. Bernatowicz and Hagee [1987] showed that Kr and Xe implanted at low energy onto tungsten are fractionated by approximately 1% per amu, favoring the heavy isotopes; we confirm these effects. We have extended these studies to Ar and Ne, using a modified Bayard-Alpert type implanter design of cylindrical symmetry with collector potentials of -40 to -100V, and observe systematically larger mass dependent isotopic fractionation for argon and neon, >=3% per amu and >=4% per amu, respectively. These fractionations scale approximately as Δm/m for all of the noble gases measured, consistent with the findings of Bernatowicz and coworkers. Experimental data at higher energies and predictions by TRIM (Transport of Ions in Matter) code simulations indicate that sticking probabilities may depend upon the mass ratios of projectile and target. Many natural environments for low-energy ion implantation existed in the early solar nebula, such as in dusty plasmas or in the interaction of the bipolar outflow with small grains or in the wind of the early active Sun with accreting planetesimals. Low-energy ions provide viable sources for gas loading onto nebular dust grains; the result is isotopic and elemental fractionation of the projectiles.

  7. Study of Biological Effects of Low Energy Ion Implantation on Tomato and Radish Breeding

    NASA Astrophysics Data System (ADS)

    Liang, Qiuxia; Huang, Qunce; Cao, Gangqiang; Ying, Fangqing; Liu, Yanbo; Huang, Wen

    2008-04-01

    Biological effects of 30 keV low energy nitrogen ion implantation on the seeds of five types of tomato and one type of radish were investigated. Results showed that low energy ions have different effects on different vegetables. The whole dose-response curve of the germination ratio did not take on "the shape of saddle", but was a rising and falling waveform with the increase or decrease in ion implantation. In the vegetable of Solanaceae, two outstanding aberrant plants were selected from M1 of Henan No.4 tomato at a dose of 7 × 1017 nitrogen ions/cm2, which had thin-leaves, long-petal and nipple tip fruit stably inherited to M7. Furthermore the analysis of the isozyme showed that the activity of the mutant tomato seedling was distinct in quantity and color. In Raphanus sativus L., the aberrances were obvious in the mutant of radish 791 at a dose of 5 × 1017 nitrogen ions/cm2, and the weight of succulent root and the volume of growth were over twice the control's. At present, many species for breeding have been identified in the field and only stable species have been selected for the experiment of production. It is evident that the low energy ion implantation technology has clear effects on vegetables' genetic improvement.

  8. Molecular ion sources for low energy semiconductor ion implantation (invited)

    NASA Astrophysics Data System (ADS)

    Hershcovitch, A.; Gushenets, V. I.; Seleznev, D. N.; Bugaev, A. S.; Dugin, S.; Oks, E. M.; Kulevoy, T. V.; Alexeyenko, O.; Kozlov, A.; Kropachev, G. N.; Kuibeda, R. P.; Minaev, S.; Vizir, A.; Yushkov, G. Yu.

    2016-02-01

    Smaller semiconductors require shallow, low energy ion implantation, resulting space charge effects, which reduced beam currents and production rates. To increase production rates, molecular ions are used. Boron and phosphorous (or arsenic) implantation is needed for P-type and N-type semiconductors, respectively. Carborane, which is the most stable molecular boron ion leaves unacceptable carbon residue on extraction grids. A self-cleaning carborane acid compound (C4H12B10O4) was synthesized and utilized in the ITEP Bernas ion source resulting in large carborane ion output, without carbon residue. Pure gaseous processes are desired to enable rapid switch among ion species. Molecular phosphorous was generated by introducing phosphine in dissociators via 4PH3 = P4 + 6H2; generated molecular phosphorous in a pure gaseous process was then injected into the HCEI Calutron-Bernas ion source, from which P4+ ion beams were extracted. Results from devices and some additional concepts are described.

  9. Molecular ion sources for low energy semiconductor ion implantation (invited).

    PubMed

    Hershcovitch, A; Gushenets, V I; Seleznev, D N; Bugaev, A S; Dugin, S; Oks, E M; Kulevoy, T V; Alexeyenko, O; Kozlov, A; Kropachev, G N; Kuibeda, R P; Minaev, S; Vizir, A; Yushkov, G Yu

    2016-02-01

    Smaller semiconductors require shallow, low energy ion implantation, resulting space charge effects, which reduced beam currents and production rates. To increase production rates, molecular ions are used. Boron and phosphorous (or arsenic) implantation is needed for P-type and N-type semiconductors, respectively. Carborane, which is the most stable molecular boron ion leaves unacceptable carbon residue on extraction grids. A self-cleaning carborane acid compound (C4H12B10O4) was synthesized and utilized in the ITEP Bernas ion source resulting in large carborane ion output, without carbon residue. Pure gaseous processes are desired to enable rapid switch among ion species. Molecular phosphorous was generated by introducing phosphine in dissociators via 4PH3 = P4 + 6H2; generated molecular phosphorous in a pure gaseous process was then injected into the HCEI Calutron-Bernas ion source, from which P4(+) ion beams were extracted. Results from devices and some additional concepts are described. PMID:26932065

  10. Modeling of Inner Surface Modification of a Cylindrical Tube by Plasma-Based Low-Energy Ion Implantation

    NASA Astrophysics Data System (ADS)

    Zheng, Bocong; Wang, Kesheng; Lei, Mingkai

    2015-04-01

    The inner surface modification process by plasma-based low-energy ion implantation (PBLEII) with an electron cyclotron resonance (ECR) microwave plasma source located at the central axis of a cylindrical tube is modeled to optimize the low-energy ion implantation parameters for industrial applications. In this paper, a magnetized plasma diffusion fluid model has been established to describe the plasma nonuniformity caused by plasma diffusion under an axial magnetic field during the pulse-off time of low pulsed negative bias. Using this plasma density distribution as the initial condition, a sheath collisional fluid model is built up to describe the sheath evolution and ion implantation during the pulse-on time. The plasma nonuniformity at the end of the pulse-off time is more apparent along the radial direction compared with that in the axial direction due to the geometry of the linear plasma source in the center and the difference between perpendicular and parallel plasma diffusion coefficients with respect to the magnetic field. The normalized nitrogen plasma densities on the inner and outer surfaces of the tube are observed to be about 0.39 and 0.24, respectively, of which the value is 1 at the central plasma source. After a 5 μs pulse-on time, in the area less than 2 cm from the end of the tube, the nitrogen ion implantation energy decreases from 1.5 keV to 1.3 keV and the ion implantation angle increases from several degrees to more than 40° both variations reduce the nitrogen ion implantation depth. However, the nitrogen ion implantation dose peaks of about 2×1010 - 7×1010 ions/cm2 in this area are 2 - 4 times higher than that of 1.18×1010 ions/cm2 and 1.63×1010 ions/cm2 on the inner and outer surfaces of the tube. The sufficient ion implantation dose ensures an acceptable modification effect near the end of the tube under the low energy and large angle conditions for nitrogen ion implantation, because the modification effect is mainly determined by the

  11. Damaging Effect of Low Energy N+ Implantation on Aspergillus niger Spores

    NASA Astrophysics Data System (ADS)

    Wang, Lisheng; Cai, Kezhou; Cheng, Maoji; Chen, Lijuan; Liu, Xuelan; Zhang, Shuqing; Yu, Zengliang

    2007-06-01

    The mutant effects of a keV range nitrogen ion (N+) beam on enzyme-producing probiotics were studied, particularly with regard to the induction in the genome. The electron spin resonance (ESR) results showed that the signal of ESR spectrum existed in both implanted and non-implanted spores, and the yields of free radicals increased in a dose-dependent manner. The ionic etching and dilapidation of cell wall could be observed distinctly through the scanning electron microscope (SEM). The mutagenic effect on genome indicated that N+ implantation could make base mutation. This study provided an insight into the roles low-energy ions might play in inducing mutagenesis of micro-organisms.

  12. Low-energy ion implantation: Large mass fractionation of argon

    NASA Technical Reports Server (NTRS)

    Ponganis, K. V.; Graf, TH.; Marti, K.

    1993-01-01

    The isotropic signatures of noble gases in the atmospheres of the Earth and other planets are considerably evolved when compared to signatures observed in the solar wind. The mechanisms driving the evolution of planetary volatiles from original compositions in the solar accretion disk are currently poorly understood. Modeling of noble-gas compositional histories requires knowledge of fractionating processes that may have operated through the evolutionary stages. Since these gases are chemically inert, information on noble-gas fractionation processes can be used as probes. The importance of understanding these processes extends well beyond 'noble-gas planetology.' Trapped argon acquired by low-energy implantation (approximately less than 100 eV) into solids is strongly mass fractionated (approximately greater than or equal to 3 percent/amu). This has potential implications for the origin and evolution of terrestrial planet atmospheres.

  13. Molecular Ion Beam Transportation for Low Energy Ion Implantation

    SciTech Connect

    Kulevoy, T. V.; Kropachev, G. N.; Seleznev, D. N.; Yakushin, P. E.; Kuibeda, R. P.; Kozlov, A. V.; Koshelev, V. A.; Hershcovitch, A.; Johnson, B. M.; Gushenets, V. I.; Oks, E. M.; Polozov, S. M.; Poole, H. J.

    2011-01-07

    A joint research and development of steady state intense boron ion sources for 100's of electron-volt ion implanters has been in progress for the past five years. Current density limitation associated with extracting and transporting low energy ion beams result in lower beam currents that in turn adversely affects the process throughput. The transport channel with electrostatic lenses for decaborane (B{sub 10}H{sub 14}) and carborane (C{sub 2}B{sub 10}H{sub 12}) ion beams transportation was developed and investigated. The significant increase of ion beam intensity at the beam transport channel output is demonstrated. The transport channel simulation, construction and experimental results of ion beam transportation are presented.

  14. Effect of low-energy hydrogen ion implantation on dendritic web silicon solar cells

    NASA Technical Reports Server (NTRS)

    Rohatgi, A.; Meier, D. L.; Rai-Choudhury, P.; Fonash, S. J.; Singh, R.

    1986-01-01

    The effect of a low-energy (0.4 keV), short-time (2-min), heavy-dose (10 to the 18th/sq cm) hydrogen ion implant on dendritic web silicon solar cells and material was investigated. Such an implant was observed to improve the cell open-circuit voltage and short-circuit current appreciably for a number of cells. In spite of the low implant energy, measurements of internal quantum efficiency indicate that it is the base of the cell, rather than the emitter, which benefits from the hydrogen implant. This is supported by the observation that the measured minority-carrier diffusion length in the base did not change when the emitter was removed. In some cases, a threefold increase of the base diffusion length was observed after implantation. The effects of the hydrogen implantation were not changed by a thermal stress test at 250 C for 111 h in nitrogen. It is speculated that hydrogen enters the bulk by traveling along dislocations, as proposed recently for edge-defined film-fed growth silicon ribbon.

  15. Low-energy plasma immersion ion implantation to induce DNA transfer into bacterial E. coli

    NASA Astrophysics Data System (ADS)

    Sangwijit, K.; Yu, L. D.; Sarapirom, S.; Pitakrattananukool, S.; Anuntalabhochai, S.

    2015-12-01

    Plasma immersion ion implantation (PIII) at low energy was for the first time applied as a novel biotechnology to induce DNA transfer into bacterial cells. Argon or nitrogen PIII at low bias voltages of 2.5, 5 and 10 kV and fluences ranging from 1 × 1012 to 1 × 1017 ions/cm2 treated cells of Escherichia coli (E. coli). Subsequently, DNA transfer was operated by mixing the PIII-treated cells with DNA. Successes in PIII-induced DNA transfer were demonstrated by marker gene expressions. The induction of DNA transfer was ion-energy, fluence and DNA-size dependent. The DNA transferred in the cells was confirmed functioning. Mechanisms of the PIII-induced DNA transfer were investigated and discussed in terms of the E. coli cell envelope anatomy. Compared with conventional ion-beam-induced DNA transfer, PIII-induced DNA transfer was simpler with lower cost but higher efficiency.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Study on the Growth and the Photosynthetic Characteristics of Low Energy C+ Ion Implantation on Peanut

    PubMed Central

    Han, Yuguo; Xu, Lei; Yang, Peiling; Ren, Shumei

    2013-01-01

    Employing the Nonghua 5 peanut as experimental material, the effects of low energy C+ ion implantation on caulis height, root length, dry weight, photosynthetic characteristics and leaf water use efficiency (WUE) of Peanut Ml Generation were studied. Four fluences were observed in the experiment. The results showed that ion implantation harmed the peanut seeds because caulis height, root length and dry weight all were lower in the treatments than in CK, and the harm was aggravated with the increase of ion fluence. Both Pn and Tr show a saddle-shape curve due to midday depression of photosynthesis. Low fluence of low energy C+ ion implantation could increase the diurnal average Pn of peanut. The diurnal variation of Tr did not change as significantly as Pn. The light saturation point (LSP) was restrained by the ions. After low energy C+ ion implantation, WUE was enhanced. When the fluence increased to a certain level, the WUE began to decrease. PMID:23861939

  18. Use of low energy hydrogen ion implants in high efficiency crystalline silicon solar cells

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.; Singh, R.

    1985-01-01

    This program is a study of the use of low energy hydrogen ion implantation for high efficiency crystalline silicon solar cells. The first quarterly report focuses on two tasks of this program: (1) an examination of the effects of low energy hydrogen implants on surface recombination speed; and (2) an examination of the effects of hydrogen on silicon regrowth and diffusion in silicon. The first part of the project focussed on the measurement of surface properties of hydrogen implanted silicon. Low energy hydrogen ions when bombarded on the silicon surface will create structural damage at the surface, deactivate dopants and introduce recombination centers. At the same time the electrically active centers such as dangling bonds will be passivated by these hydrogen ions. Thus hydrogen is expected to alter properties such as the surface recombination velocity, dopant profiles on the emitter, etc. In this report the surface recombination velocity of a hydrogen emplanted emitter was measured.

  19. Use of low-energy hydrogen ion implants in high-efficiency crystalline-silicon solar cells

    NASA Technical Reports Server (NTRS)

    Fonash, S. J.; Sigh, R.; Mu, H. C.

    1986-01-01

    The use of low-energy hydrogen implants in the fabrication of high-efficiency crystalline silicon solar cells was investigated. Low-energy hydrogen implants result in hydrogen-caused effects in all three regions of a solar cell: emitter, space charge region, and base. In web, Czochralski (Cz), and floating zone (Fz) material, low-energy hydrogen implants reduced surface recombination velocity. In all three, the implants passivated the space charge region recombination centers. It was established that hydrogen implants can alter the diffusion properties of ion-implanted boron in silicon, but not ion-implated arsenic.

  20. Low Energy, Low Emissions: Sulfur Dioxide; Nitrogen Oxides, and Carbon Dioxide in Western Europe.

    ERIC Educational Resources Information Center

    Alcamo, Joseph; De Vries, Bert

    1992-01-01

    Links proposed low-energy scenarios for different Western European countries with the amount of pollutants that may result from these scenarios. Sulfur dioxide, nitrogen oxide, and carbon dioxide emissions are calculated for the 10 countries for which low-energy scenarios are available, resulting in reductions of 54%, 37%, and 40%, respectively.…

  1. Observations of nitrogen and oxygen isotopes in the low energy cosmic rays. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Vidor, S. B.

    1975-01-01

    The isotopic composition of low-energy nitrogen and oxygen cosmic rays was measured with an electron/isotope spectrometer aboard the IMP-7 satellite to determine the possible source of the particles. Instrument calibration showed the standard range-energy tables to be inadequate to calculate the isotope response, and corrections were obtained. The low-energy nitrogen and oxygen cosmic rays were found to be primarily 14N and 16O. Upper limits were obtained for the abundances of the other stable nitrogen and oxygen isotopes. The nitrogen composition differs from higher energy measurements which indicate that 15N, which is thought to be secondary, is the dominant isotope.

  2. Interstitial injection in silicon after high-dose, low-energy arsenic implantation and annealing

    SciTech Connect

    Tsamis, C.; Skarlatos, D.; BenAssayag, G.; Claverie, A.; Lerch, W.; Valamontes, V.

    2005-11-14

    In this work, we investigate the interstitial injection into the silicon lattice due to high-dose, low-energy arsenic implantation. The approach consists in monitoring the diffusion of the arsenic profile as well as of the boron profile in buried {delta}-doped layers, when amounts of the as-implanted arsenic profile are removed by low-temperature wet silicon etching. The experimental results indicate that the contribution of the implantation damage to the transient enhanced diffusion of boron, and thus the interstitial injection, is not the main one. On the contrary, interstitial generation due to arsenic clustering seems to be more important for the present conditions.

  3. Investigation of Mn-implanted n-Si by low-energy ion beam deposition

    NASA Astrophysics Data System (ADS)

    Liu, Lifeng; Chen, Nuofu; Song, Shulin; Yin, Zhigang; Yang, Fei; Chai, Chunlin; Yang, Shaoyan; Liu, Zhikai

    2005-01-01

    Mn ions were implanted to n-type Si(0 0 1) single crystal by low-energy ion beam deposition technique with an energy of 1000 eV and a dose of 7.5×10 17 cm -2. The samples were held at room temperature and at 300 °C during implantation. Auger electron spectroscopy depth profiles of samples indicate that the Mn ions reach deeper in the sample implanted at 300 °C than in the sample implanted at room temperature. X-ray diffraction measurements show that the structure of the sample implanted at room temperature is amorphous while that of the sample implanted at 300 °C is crystallized. There are no new phases found except silicon both in the two samples. Atomic force microscopy images of samples indicate that the sample implanted at 300 °C has island-like humps that cover the sample surface while there is no such kind of characteristic in the sample implanted at room temperature. The magnetic properties of samples were investigated by alternating gradient magnetometer (AGM). The sample implanted at 300 °C shows ferromagnetic behavior at room temperature.

  4. Low-energy positron and electron scattering from nitrogen dioxide

    NASA Astrophysics Data System (ADS)

    Chiari, Luca; Zecca, Antonio; García, Gustavo; Blanco, Francisco; Brunger, M. J.

    2013-12-01

    Total cross section (TCS) measurements for positron scattering from nitrogen dioxide (NO2) are presented in the energy range 0.2-40 eV. The TCS, the elastic integral and differential cross sections, and the integral cross section accounting of all the inelastic processes (including positronium formation) have also been computed using the independent atom model with screening corrected additivity rule (IAM-SCAR) for incident energies from 1 to 1000 eV. A qualitative level of agreement is found between the present TCS experiment and theory at the common energies. As no previous measurements or calculations for positron-NO2 scattering exist in the literature, we also computed the TCS for electron collisions with NO2 employing the IAM-SCAR method. A comparison of those results to the present positron cross sections and the earlier electron-impact data and calculations is provided. To investigate the role that chemical substitution plays in positron scattering phenomena, we also compare the present positron-NO2 data with the TCSs measured at the University of Trento for positron scattering from N2O and CO2.

  5. Implantation of nitrogen: Effects of hydrogen and implantation energy

    NASA Technical Reports Server (NTRS)

    Sugiura, Naoji; Futagami, Tsuneji; Nagai, Siro

    1993-01-01

    To solve the question on solar nitrogen in lunar soils, i.e. variation in isotopic composition and apparently high retentivity compared with rare gases, nitrogen implantation experiments were conducted. At the Meteoritical Society Meeting in Copenhagen, the results of stepped combustion of implanted nitrogen in ilmenite and olivine were presented. The degassing behavior of nitrogen (and also Ar) was quite different from that observed in the case of lunar soils. Extraction temperatures are higher (greater than 1100 C for ilmenite and 1500 C for olivine) than that for lunar soils. Both nitrogen and Ar seem to be retained at the same efficiency. Therefore, additional experiments were conducted to make degassing behavior of nitrogen more close to that observed in the case of lunar soils.

  6. Isotopic fractionation of Kr and Xe implanted in solids at very low energies

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.; Hagee, Bryan E.

    1987-01-01

    Results on the implantation of Kr and Xe in W under closed system conditions at very low energies (50-500 eV) are reported. Investigation of the fraction of gas trapped as a function of time reveals the existence of competing trapping and release mechanisms, and analysis of recovered trapped gas and residual gas phases shows that both elemental and isotropic fractionation result from these mechanisms. It is determined that the mass dependence for the overall implantation process is at or near m exp 1, with heavier isotopes enriched in the implanted gas. This mass dependence is inferred to result from implantation and a combination of diffusive and gas sputtering release mechanisms. These results reaffirm the conclusion of Bernatowicz and Fahey (1986) that previously observed isotopic fractionation of Kr and Xe in carbonaceous material synthesized in electrical discharges owes its origin to low-energy ion implantation, and also suggest that this process may be relevant to incorporation of noble gases in early solar system materials. The implication of these results for noble gas mass spectrometry are discussed.

  7. Surface Oxidation Effects During Low Energy BF{sub 2}{sup +} Ion Implantation

    SciTech Connect

    Kondratenko, Serguei; Hsu, P. K.; Zhao, Hongchen; Reece, Ronald N.

    2011-01-07

    We present results on silicon wafer surface oxidation observed during low energy high dose BF{sub 2}{sup +} implantation. Experiments were performed on single-crystal and pre-amorphized silicon wafers that help elucidate the surface structure impact on boron distribution profiles and dose retention. Implanters with different architectures were compared including both single wafer and batch systems. It was found that the oxidation rate depends on implanter type and design, and that the surface oxide thickness is a linear function of implantation dose and time. Surface oxidation is significantly higher for batch systems compared to single wafer tools. This is due primarily to the significantly lower beam duty cycle on the batch implanter. The oxide thicknesses estimated from SIMS oxygen profiles are in agreement with ellipsometry measurements after spike annealing, and show a similar difference between single wafer and batch implanters. SIMS boron distribution profiles after implantation were compared and used to calculate retained dose. In the medium dose range ({<=}3x10{sup 14} at/cm{sup 2}) the profiles from different implanters are well matched and the dose retention is close to 100%. For the higher dose range ({>=}3x10{sup 15} at/cm{sup 2}) retention for the batch implanter is significantly less than the single wafer tool and depends on the wafer surface structure. A higher oxidation rate results in lower dopant activation and higher Rs value after spike annealing. For high implantation doses the single wafer system allows much higher dose retention and better boron activation after annealing.

  8. Molecular dynamics simulation of low energy boron and arsenic implant into silicon

    SciTech Connect

    Beardmore, K.; Cai, D.; Gronbech-Jensen, N.

    1996-07-01

    We have studied the implantation of boron and arsenic ions into silicon by classical molecular dynamics simulation. Single ion implant into the dimer reconstructed Si{l_brace}100{r_brace}(2x1) surface has been examined at energies between 0.25 keV and 5.0 keV, at both normal incidence and at non-channeling incidence. By using a new model for electronic stopping, developed for semiconductors and containing only one fitted parameter, we have been able to accurately calculate the depth profile of the implanted B and as atoms. The results of the calculations are compared to the predictions from a binary collision (BC) model for the dopant profile, and to experimental data. This allows us to examine the low energy limits on the validity of the BC approximation, with the aim of producing modifications to the BC model to extend its validity into the sub-keV regime.

  9. Photovoltage improvements in Cz–Si by low-energy implantation of carbon ions

    NASA Astrophysics Data System (ADS)

    Nadtochiy, A.; Korotchenkov, O.; Romanyuk, B.; Melnik, V.; Popov, V.

    2016-05-01

    We demonstrate photovoltage improvements in Czochralski-grown silicon wafers by low-energy implantation of carbon ions. After annealing at temperatures above ≈550 °C the surface photovoltage (SPV) increases in both implanted and unimplanted sample sets. The increase in the SPV signal observed in implanted samples, which are subsequently annealed at 650 °C and 750 °C, is roughly two times greater than the appropriate values observed in unimplanted wafers. The effect in implanted samples is accompanied by longer time decays in the SPV transients (roughly from several to hundreds of microseconds). In marked contrast, unimplanted samples do not show such a significant difference in the decay times upon annealing. The decay times are fairly evenly distributed across the surface of the implanted but unannealed wafer, whereas the surface distribution function is essentially non-uniform in annealed samples. The results are discussed in terms of the temperature specific defect chemistry. The results of this work open new possibilities for studying defect rearrangement and clustering of atoms in implanted Si and advancing the development of silicon based photovoltaic materials with high photovoltage response. Supplementary data are available from stacks.iop.org/SST/.

  10. Tribological characteristics of nitrogen (N+) implanted iron

    NASA Technical Reports Server (NTRS)

    Jones, W. R.; Ferrante, J.

    1982-01-01

    The effect of implantation of nitrogen ions (1.5 MeV) on the friction and wear characteristics of pure ion sliding against M-50 steel (unimplanted) was studied in a pin-on-disk sliding friction apparatus. Test conditions included room temperature (25 C), a dry air atmosphere, a load of 1/2 kg (4.9 N), sliding velocities of 0.043 to 0.078 m/sec (15 to 25 rpm), a pure hydrocarbon lubricant (n-hexadecane), or a U.S.P. mineral oil and nitrogen ion implantation doses of 5x10 to the 15th power and 5x10 to the 17th power ions/sq cm. No differences in wear rates were observed in the low dose experiments. In the high dose experiments, small reductions in initial (40 percent) and steady state (20 percent) wear rates were observed for nitrogen implanted iron riders as compared with unimplanted controls. No differences in average friction coefficients were noted for either dose. Auger electron spectroscopy combined with argon ion bombardment revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 6 atomic percent at a depth of 0.8 microns. Similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration. No inward migration of nitrogen ions was observed.

  11. Tribological characteristics of nitrogen (N+) implanted iron

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Ferrante, J.

    1983-01-01

    The effect of implantation of nitrogen ions (1.5 MeV) on the friction and wear characteristics of pure ion sliding against M-50 steel (unimplanted) was studied in a pin-on-disk sliding friction apparatus. Test conditions included room temperature (25 C), a dry air atmosphere, a load of 1/2 kg (4.9 N), sliding velocities of 0.043 to 0.078 m/sec (15 to 25 rpm), a pure hydrocarbon lubricant (n-hexadecane), or a U.S.P. mineral oil and nitrogen ion implantation doses of 5x10 to the 15th power and 5x10 to the 17th power ions/sq cm. No differences in wear rates were observed in the low dose experiments. In the high dose experiments, small reductions in initial (40 percent) and steady state (20 percent) wear rates were observed for nitrogen implanted iron riders as compared with unimplanted controls. No differences in average friction coefficients were noted for either dose. Auger electron spectroscopy combined with argon ion bombardment revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 6 atomic percent at a depth of 0.8 microns. Similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration. No inward migration of nitrogen ions was observed. Previously announced in STAR as N82-24322

  12. Sources and transport systems for low energy extreme of ion implantation

    SciTech Connect

    Hershcovitch, A.; Batalin, V.A.; Bugaev, A.S.; Gushenets, V.I.; Alexeyenko, O.; Gurkova, E.; Johnson, B.M.; Kolomiets, A.A.; Kropachev, G.N.; Kuibeda, R.P.; Kulevoy, T.V.; Masunov, E.S.; Oks, E.M.; Pershin, V.I.; Polozov, S.M.; Poole, H.J.; Seleznev, D.N.; Storozhenko, P.A.; Vizir, A.; Svarovski, A.Ya.; Yakushin, P.; Yushkov, G.Yu.

    2010-06-06

    For the past seven years a joint research and development effort focusing on the design of steady state, intense ion sources has been in progress with the ultimate goal being to meet the two, energy extreme range needs of mega-electron-volt and 100's of electron-volt ion implanters. However, since the last Fortier is low energy ion implantation, focus of the endeavor has shifted to low energy ion implantation. For boron cluster source development, we started with molecular ions of decaborane (B{sub 10}H{sub 14}), octadecaborane (B{sub 18}H{sub 22}), and presently our focus is on carborane (C{sub 2}B{sub 10}H{sub 12}) ions developing methods for mitigating graphite deposition. Simultaneously, we are developing a pure boron ion source (without a working gas) that can form the basis for a novel, more efficient, plasma immersion source. Our Calutron-Berna ion source was converted into a universal source capable of switching between generating molecular phosphorous P{sub 4}{sup +}, high charge state ions, as well as other types of ions. Additionally, we have developed transport systems capable of transporting a very large variety of ion species, and simulations of a novel gasless/plasmaless ion beam deceleration method were also performed.

  13. Effects of implant temperature on process characteristics of low energy boron implanted silicon

    NASA Astrophysics Data System (ADS)

    Liu, Lequn Jennifer; Hsu, Wei Hui; Brumfield, Kyle; Padmanabhan, Radha; Morinville, Wendy; Qin, Shu; Hu, Yongjun Jeff; McTeer, Allen

    2012-11-01

    The effects of self-amorphization thickness on boron (B) dopant depth profile in silicon (Si) were investigated by cold temperature implant, down to -100°C. Significant B junction depth (Xj) reduction can be achieved for as-implant and post anneal, when the self-amorphization thickness is comparable or deeper than the B implant projected range (implant peak position) and the implant is completed at sufficiently low temperature. There is a transition temperature regime before the appropriate temperature is reached. The Xj reduction is stagnated due to the thickness limitation and the degree of self-amorphization. Temperature dependent surface damage, self-amorphization thickness, diffusion, and activation were also studied. Improvement in carrier mobility is more significant in certain dose regimes at low temperatures. The findings of this study provide important insight in to the control of the junction profile for smaller atomic mass unit (AMU) species, like B, by using the self-amorphization effect at cold temperatures.

  14. Low energy and low fluence helium implantations in tungsten: Molecular dynamics simulations and experiments

    NASA Astrophysics Data System (ADS)

    Pentecoste, L.; Brault, P.; Thomann, A.-L.; Desgardin, P.; Lecas, T.; Belhabib, T.; Barthe, M.-F.; Sauvage, T.

    2016-03-01

    300 eV Helium implantation process into tungsten at 300 K has been studied with molecular dynamic simulations (MD). Predicted retention doses were compared to that obtained from experiments performed in equivalent conditions. A saturation phenomenon of the helium retention was evidenced for a number of impinging He atoms and a retention dose similar in both, experiments and simulations. From MD simulations it is learnt that observed Helium diffusion, formation and coalescence of clusters are the phenomena leading to the flaking of the substrate. These processes could explain the saturation of the Helium retention observed experimentally at low energies.

  15. Defect diffusion during annealing of low-energy ion-implanted silicon

    SciTech Connect

    Bedrossian, P J; Caturla, M-J; Diaz de la Rubia, T

    2000-03-08

    We present a new approach for investigating the kinetics of defect migration during annealing of low-energy, ion-implanted silicon, employing a combination of computer simulations and atomic-resolution tunneling microscopy. Using atomically-clean Si(111)-7x7 as a sink for bulk point defects created by 5 keV Xe and Ar irradiation, we observe distinct, temperature-dependent surface arrival rates for vacancies and interstitials. A combination of simulation tools provides a detailed description of the processes that underly the observed temperature-dependence of defect segregation, and the predictions of the simulations agree closely with the experimental observations.

  16. Incorporation of low energy activated nitrogen onto HOPG surface: Chemical states and thermal stability studies by in-situ XPS and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chandran, Maneesh; Shasha, Michal; Michaelson, Shaul; Hoffman, Alon

    2016-09-01

    In this paper we report the chemical states analysis of activated nitrogen incorporated highly oriented pyrolytic graphite (HOPG) surface under well-controlled conditions. Nitrogen incorporation is carried out by two different processes: an indirect RF nitrogen plasma and low energy (1 keV) N2+ implantation. Bonding configuration, concentration and thermal stability of the incorporated nitrogen species by aforesaid processes are systematically compared by in-situ X-ray photoelectron spectroscopy (XPS). Relatively large concentration of nitrogen is incorporated onto RF nitride HOPG surface (16.2 at.%), compared to N2+ implanted HOPG surface (7.7 at.%). The evolution of N 1s components (N1, N2, N3) with annealing temperature is comprehensively discussed, which indicates that the formation and reorganization of local chemical bonding states are determined by the process of nitridation and not by the prior chemical conditioning (i.e., amorphization or hydrogenation) of the HOPG surface. A combined XPS and Raman spectroscopy studies revealed that N2+ implantation process resulted in a high level of defects to the HOPG surface, which cannot be annealed-out by heat treatment up to 1000 °C. On the other hand, the RF nitrogen plasma process did not produce a high level of surface defects, while incorporating nearly the same amount of stable nitrogen species.

  17. Direct synthesis of ultrathin SOI structure by extremely low-energy oxygen implantation

    NASA Astrophysics Data System (ADS)

    Hoshino, Yasushi; Yachida, Gosuke; Inoue, Kodai; Toyohara, Taiga; Nakata, Jyoji

    2016-06-01

    We performed extremely low-energy 16O+ implantation at 10 keV (Rp ˜ 25 nm) followed by annealing aiming at directly synthesizing an ultrathin Si layer separated by a buried SiO2 layer in Si(001) substrates, and then investigated feasible condition of recrystallization and stabilization of the superficial Si and the buried oxide layer by significantly low temperature annealing. The elemental compositions were analyzed by Rutherford backscattering (RBS) and secondary ion mass spectroscopy (SIMS). The crystallinity of the superficial Si layer was quantitatively confirmed by ananlyzing RBS-channeling spectra. Cross-sectional morphologies and atomic configurations were observed by transmission electron microscope (TEM). As a result, we succeeded in directly synthesizing an ultrathin single-crystalline silicon layer with ≤20 nm thick separated by a thin buried stoichiometric SiO2 layer with ≤20 nm thick formed by extremely low-energy 16O+ implantation followed by surprisingly low temperature annealing at 1050∘ C.

  18. A novel mechanism of ultrathin SOI synthesis by extremely low-energy hot O+ implantation

    NASA Astrophysics Data System (ADS)

    Hoshino, Yasushi; Yachida, Gosuke; Inoue, Kodai; Toyohara, Taiga; Nakata, Jyoji

    2016-08-01

    Extremely low-energy oxygen implantations at 10 keV in silicon were challengingly performed to directly synthesize ultrathin silicon-on-insulator (SOI) structure separated by a buried oxide (BOX) layer. We quantitatively investigated the optimum condition and the formation mechanism of homogeneous and continuous stoichiometric SOI/BOX structure. In this study, oxygen ions were implanted into Si(0 0 1) substrates with keeping the temperatures at 500, 800, and 1000 °C with ion-fluences from 0.5 to 2.0× {{10}17} ions cm‑2. These samples were then postannealed at high temperatures from 950 to 1150 °C in Ar ambient for several hours. We found that ultrathin stoichiometric SOI/BOX structure with less than 20 nm thick was synthesized by oxygen implantation with an ion dose of 1.0× {{10}17} ions cm‑2 from 500 °C to 800 °C followed by annealing at a significantly low temperature of 1050 °C for 5 h. According to the RBS-channeling analysis, the crystallinity was excellent as quality as that of the SOI structure formed by a wafer-bonding method. We found that the BOX layer was finally formed around the deeper end of the oxygen distribution in the as-implanted sample, though the depth of the BOX formation was much deeper than the projected range of oxygen and the damage peak of silicon. The formation process of the SOI/BOX structure proposed so far could not be applicable to the present conditions for ultrathin SOI/BOX synthesis by extremely low-energy implantation followed by low-temperature annealing. We thus suggested a novel mechanism of the ultrathin SOI/BOX synthesis as follows. The mechanism during the thermal treatment was demonstrated that the recrystallization of the damaged Si layers induced by ion irradiation took place from the very surface with relatively less irradiation-damages toward deeper layers with sweeping interstitial oxygen atoms, and the condensed oxygen atoms finally synthesized the stoichiometric BOX layer.

  19. Segregation and enhanced diffusion of nitrogen in silicon induced by low energy ion bombardment

    SciTech Connect

    Stoddard, N.; Duscher, G.; Karoui, A.; Stevie, F.; Rozgonyi, G.

    2005-04-15

    A sample of nitrogen-doped, single crystal Czochralski silicon was subjected to several different surface preparations. Secondary ion mass spectrometry depth profiling has shown that prolonged glancing-angle bombardment by 3-5 kV Ar{sup +} ions significantly increases the nitrogen concentration in the near surface by up to an order of magnitude over the bulk value. Concentrations are observed to be elevated over the bulk value to a depth up to 25 {mu}m. Nitrogen-implanted samples and samples with a 1 nm surface nitride did not exhibit nitrogen segregation under the same conditions, but a sample with 100 nm of surface nitride did exhibit ion bombardment induced drive-in. In nitride-free samples, the source of the nitrogen is indicated to be a nitrogen-rich layer in the first micron of material. The diffusion behavior of nitrogen in silicon is discussed and the Crowdion mechanism for diffusion is suggested as the enabling mechanism for the enhanced low temperature diffusion.

  20. Nitrogen ion implantation into various materials using 28 GHz electron cyclotron resonance ion source.

    PubMed

    Shin, Chang Seouk; Lee, Byoung-Seob; Choi, Seyong; Yoon, Jang-Hee; Kim, Hyun Gyu; Ok, Jung-Woo; Park, Jin Yong; Kim, Seong Jun; Bahng, Jungbae; Hong, Jonggi; Lee, Seung Wook; Won, Mi-Sook

    2016-02-01

    The installation of the 28 GHz electron cyclotron resonance ion source (ECRIS) ion implantation beamline was recently completed at the Korea Basic Science Institute. The apparatus contains a beam monitoring system and a sample holder for the ion implantation process. The new implantation system can function as a multipurpose tool since it can implant a variety of ions, ranging hydrogen to uranium, into different materials with precise control and with implantation areas as large as 1-10 mm(2). The implantation chamber was designed to measure the beam properties with a diagnostic system as well as to perform ion implantation with an in situ system including a mass spectrometer. This advanced implantation system can be employed in novel applications, including the production of a variety of new materials such as metals, polymers, and ceramics and the irradiation testing and fabrication of structural and functional materials to be used in future nuclear fusion reactors. In this investigation, the first nitrogen ion implantation experiments were conducted using the new system. The 28 GHz ECRIS implanted low-energy, multi-charged nitrogen ions into copper, zinc, and cobalt substrates, and the ion implantation depth profiles were obtained. SRIM 2013 code was used to calculate the profiles under identical conditions, and the experimental and simulation results are presented and compared in this report. The depths and ranges of the ion distributions in the experimental and simulation results agree closely and demonstrate that the new system will enable the treatment of various substrates for advanced materials research. PMID:26931931

  1. Nitrogen ion implantation into various materials using 28 GHz electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Shin, Chang Seouk; Lee, Byoung-Seob; Choi, Seyong; Yoon, Jang-Hee; Kim, Hyun Gyu; Ok, Jung-Woo; Park, Jin Yong; Kim, Seong Jun; Bahng, Jungbae; Hong, Jonggi; Lee, Seung Wook; Won, Mi-Sook

    2016-02-01

    The installation of the 28 GHz electron cyclotron resonance ion source (ECRIS) ion implantation beamline was recently completed at the Korea Basic Science Institute. The apparatus contains a beam monitoring system and a sample holder for the ion implantation process. The new implantation system can function as a multipurpose tool since it can implant a variety of ions, ranging hydrogen to uranium, into different materials with precise control and with implantation areas as large as 1-10 mm2. The implantation chamber was designed to measure the beam properties with a diagnostic system as well as to perform ion implantation with an in situ system including a mass spectrometer. This advanced implantation system can be employed in novel applications, including the production of a variety of new materials such as metals, polymers, and ceramics and the irradiation testing and fabrication of structural and functional materials to be used in future nuclear fusion reactors. In this investigation, the first nitrogen ion implantation experiments were conducted using the new system. The 28 GHz ECRIS implanted low-energy, multi-charged nitrogen ions into copper, zinc, and cobalt substrates, and the ion implantation depth profiles were obtained. SRIM 2013 code was used to calculate the profiles under identical conditions, and the experimental and simulation results are presented and compared in this report. The depths and ranges of the ion distributions in the experimental and simulation results agree closely and demonstrate that the new system will enable the treatment of various substrates for advanced materials research.

  2. Creation of High-Yield Polyhydroxyalkanoates Engineered Strains by Low Energy Ion Implantation

    NASA Astrophysics Data System (ADS)

    Qian, Shiquan; Cheng, Ying; Zhu, Suwen; Cheng, Beijiu

    2008-12-01

    Polyhydroxyalkanoates (PHAs), as a candidate for biodegradable plastic materials, can be synthesized by numerous microorganisms. However, as its production cost is high in comparison with those of chemically synthesized plastics, a lot of research has been focused on the efficient production of PHAs using different methods. In the present study, the mutation effects of PHAs production in strain pCB4 were investigated with implantation of low energy ions. It was found that under the implantation conditions of 7.8 × 1014 N+/cm2 at 10 keV, a high-yield PHAs strain with high genetic stability was generated from many mutants. After optimizing its fermentation conditions, the biomass, PHAs concentration and PHAs content of pCBH4 reached 2.26 g/L, 1.81 g/L, and 80.08% respectively, whereas its wild type controls were about 1.24 g/L, 0.61 g/L, and 49.20%. Moreover, the main constituent of PHAs was identified as poly-3-hydroxybutyrates (PHB) in the mutant stain and the yield of this compound was increased up to 41.33% in contrast to that of 27.78% in the wild type strain.

  3. Predicting Low Energy Dopant Implant Profiles in Semiconductors using Molecular Dynamics

    SciTech Connect

    Beardmore, K.M.; Gronbech-Jensen, N.

    1999-05-02

    The authors present a highly efficient molecular dynamics scheme for calculating dopant density profiles in group-IV alloy, and III-V zinc blende structure materials. Their scheme incorporates several necessary methods for reducing computational overhead, plus a rare event algorithm to give statistical accuracy over several orders of magnitude change in the dopant concentration. The code uses a molecular dynamics (MD) model to describe ion-target interactions. Atomic interactions are described by a combination of 'many-body' and pair specific screened Coulomb potentials. Accumulative damage is accounted for using a Kinchin-Pease type model, inelastic energy loss is represented by a Firsov expression, and electronic stopping is described by a modified Brandt-Kitagawa model which contains a single adjustable ion-target dependent parameter. Thus, the program is easily extensible beyond a given validation range, and is therefore truly predictive over a wide range of implant energies and angles. The scheme is especially suited for calculating profiles due to low energy and to situations where a predictive capability is required with the minimum of experimental validation. They give examples of using the code to calculate concentration profiles and 2D 'point response' profiles of dopants in crystalline silicon and gallium-arsenide. Here they can predict the experimental profile over five orders of magnitude for <100> and <110> channeling and for non-channeling implants at energies up to hundreds of keV.

  4. Magnetization suppression in Co/Pd and CoCrPt by nitrogen ion implantation for bit patterned media fabrication

    NASA Astrophysics Data System (ADS)

    Sato, Kenji; Ajan, Antony; Aoyama, Nobuhide; Tanaka, Tsutomu; Miyaguchi, Yusuke; Tsumagari, Kanako; Morita, Tadashi; Nishihashi, Tsutomu; Tanaka, Atsushi; Uzumaki, Takuya

    2010-06-01

    We propose a bit patterned media fabrication method based on low energy nitrogen ion implantation. Nitrogen ion implantation of fcc-Co/Pd multilayer or hcp-CoCrPt single layer suppresses their magnetizations at room temperature. Ion implantation reduces the Curie temperature from 600 to 400 K (or lower) as a result of lattice expansion and reduced exchange interaction between the magnetic atoms in the magnetic layer. We have made media with magnetic dots of 190 to 30 nm in diameter by nitrogen ion doping through resist patterns. Writing and reading of the signal from individual dots were performed with a commercial perpendicular magnetic recording head.

  5. Shallow nitrogen ion implantation: Evolution of chemical state and defect structure in titanium

    NASA Astrophysics Data System (ADS)

    Manojkumar, P. A.; Chirayath, V. A.; Balamurugan, A. K.; Krishna, Nanda Gopala; Ilango, S.; Kamruddin, M.; Amarendra, G.; Tyagi, A. K.; Raj, Baldev

    2016-09-01

    Evolution of chemical states and defect structure in titanium during low energy nitrogen ion implantation by Plasma Immersion Ion Implantation (PIII) process is studied. The underlying process of chemical state evolution is investigated using secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The implantation induced defect structure evolution as a function of dose is elucidated using variable energy positron annihilation Doppler broadening spectroscopy (PAS) and the results were corroborated with chemical state. Formation of 3 layers of defect state was modeled to fit PAS results.

  6. Doping of Graphene by Low-Energy Ion Beam Implantation: Structural, Electronic, and Transport Properties.

    PubMed

    Willke, Philip; Amani, Julian A; Sinterhauf, Anna; Thakur, Sangeeta; Kotzott, Thomas; Druga, Thomas; Weikert, Steffen; Maiti, Kalobaran; Hofsäss, Hans; Wenderoth, Martin

    2015-08-12

    We investigate the structural, electronic, and transport properties of substitutional defects in SiC-graphene by means of scanning tunneling microscopy and magnetotransport experiments. Using ion incorporation via ultralow energy ion implantation, the influence of different ion species (boron, nitrogen, and carbon) can directly be compared. While boron and nitrogen atoms lead to an effective doping of the graphene sheet and can reduce or raise the position of the Fermi level, respectively, (12)C(+) carbon ions are used to study possible defect creation by the bombardment. For low-temperature transport, the implantation leads to an increase in resistance and a decrease in mobility in contrast to undoped samples. For undoped samples, we observe in high magnetic fields a positive magnetoresistance that changes to negative for the doped samples, especially for (11)B(+)- and (12)C(+)-ions. We conclude that the conductivity of the graphene sheet is lowered by impurity atoms and especially by lattice defects, because they result in weak localization effects at low temperatures. PMID:26120803

  7. Optimization of L(+)-Lactic Acid Production from Xylose with Rhizopus Oryzae Mutant RLC41-6 Breeding by Low-Energy Ion Implantation

    NASA Astrophysics Data System (ADS)

    Yang, Yingge; Fan, Yonghong; Li, Wen; Wang, Dongmei; Wu, Yuejin; Zheng, Zhiming; Yu, Zengliang

    2007-10-01

    In order to obtain an industrial strain with a higher L(+)-lactic acid yield, the strain Rhizopus oryzae PW352 was mutated by means of nitrogen ion beam implantation and the mutant strain Rhizopus oryzae RLC41-6 was obtained. An experimental finding was made in surprise that Rhizopus oryzae mutant RLC41-6 is not only an L(+)-lactic acid producer from corn starch but also an efficient producer of L(+)-lactic acid from xylose. Under optimal conditions, the production of L(+)-lactic acid from 100 g/L xylose reached 77.39 g/L after 144 h fed-batch fermentation. A high mutation rate and a wide mutation spectrum of low-energy ion implantation were observed in the experiment.

  8. Cracks and blisters formed close to a silicon wafer surface by He-H co-implantation at low energy

    NASA Astrophysics Data System (ADS)

    Cherkashin, N.; Daghbouj, N.; Darras, F.-X.; Fnaiech, M.; Claverie, A.

    2015-12-01

    We have studied the effect of reducing the implantation energy towards low keV values on the areal density of He and H atoms stored within populations of blister cavities formed by co-implantation of the same fluence of He then H ions into Si(001) wafers and annealing. Using a variety of experimental techniques, we have measured blister heights and depth from the surface, diameter, areal density of the cracks from which they originate as functions of implantation energy and fluence. We show that there is a direct correlation between the diameters of the cracks and the heights of the associated blisters. This correlation only depends on the implantation energy, i.e., only on the depth at which the cracks are located. Using finite element method modeling, we infer the pressure inside the blister cavities from the elastic deformations they generate, i.e., from the height of the blisters. From this, we demonstrate that the gas pressure within a blister only depends on the diameter of the associated crack and not on its depth position and derive an analytical expression relating these parameters. Relating the pressure inside a blister to the respective concentrations of gas molecules it contains, we deduce the areal densities of He and H atoms contained within the populations of blisters. After low-energy implantations (8 keV He+, 3 keV H+), all the implanted He and H atoms contribute to the formation of the blisters. There is no measurable exo-diffusion of any of the implanted gases, in contrast to what was assumed at the state of the art to explain the failure of the Smart-Cut technology when using very low energy ion implantation for the fabrication of ultra-thin layers. Alternative explanations must be investigated.

  9. Cracks and blisters formed close to a silicon wafer surface by He-H co-implantation at low energy

    SciTech Connect

    Cherkashin, N. Darras, F.-X.; Claverie, A.; Daghbouj, N.; Fnaiech, M.

    2015-12-28

    We have studied the effect of reducing the implantation energy towards low keV values on the areal density of He and H atoms stored within populations of blister cavities formed by co-implantation of the same fluence of He then H ions into Si(001) wafers and annealing. Using a variety of experimental techniques, we have measured blister heights and depth from the surface, diameter, areal density of the cracks from which they originate as functions of implantation energy and fluence. We show that there is a direct correlation between the diameters of the cracks and the heights of the associated blisters. This correlation only depends on the implantation energy, i.e., only on the depth at which the cracks are located. Using finite element method modeling, we infer the pressure inside the blister cavities from the elastic deformations they generate, i.e., from the height of the blisters. From this, we demonstrate that the gas pressure within a blister only depends on the diameter of the associated crack and not on its depth position and derive an analytical expression relating these parameters. Relating the pressure inside a blister to the respective concentrations of gas molecules it contains, we deduce the areal densities of He and H atoms contained within the populations of blisters. After low-energy implantations (8 keV He{sup +}, 3 keV H{sup +}), all the implanted He and H atoms contribute to the formation of the blisters. There is no measurable exo-diffusion of any of the implanted gases, in contrast to what was assumed at the state of the art to explain the failure of the Smart-Cut technology when using very low energy ion implantation for the fabrication of ultra-thin layers. Alternative explanations must be investigated.

  10. Effective dopant activation by susceptor-assisted microwave annealing of low energy boron implanted and phosphorus implanted silicon

    SciTech Connect

    Zhao, Zhao; Vemuri, Rajitha N. P.; Alford, T. L.; David Theodore, N.; Lu, Wei; Lau, S. S.; Lanz, A.

    2013-12-28

    Rapid processing and reduced end-of-range diffusion result from susceptor-assisted microwave (MW) annealing, making this technique an efficient processing alternative for electrically activating dopants within ion-implanted semiconductors. Sheet resistance and Hall measurements provide evidence of electrical activation. Susceptor-assisted MW annealing, of ion-implanted Si, enables more effective dopant activation and at lower temperatures than required for rapid thermal annealing (RTA). Raman spectroscopy and ion channeling analyses are used to monitor the extent of ion implantation damage and recrystallization. The presence and behavior of extended defects are monitored by cross-section transmission electron microscopy. Phosphorus implanted Si samples experience effective electrical activation upon MW annealing. On the other hand, when boron implanted Si is MW annealed, the growth of extended defects results in reduced crystalline quality that hinders the electrical activation process. Further comparison of dopant diffusion resulting from MW annealing and rapid thermal annealing is performed using secondary ion mass spectroscopy. MW annealed ion implanted samples show less end-of-range diffusion when compared to RTA samples. In particular, MW annealed P{sup +} implanted samples achieve no visible diffusion and equivalent electrical activation at a lower temperature and with a shorter time-duration of annealing compared to RTA. In this study, the peak temperature attained during annealing does not depend on the dopant species or dose, for susceptor-assisted MW annealing of ion-implanted Si.

  11. Tribological performance of surfaces enhanced by texturing and nitrogen implantation

    NASA Astrophysics Data System (ADS)

    Liu, Derong; Zhang, Qi; Qin, Zhenbo; Luo, Qin; Wu, Zhong; Liu, Lei

    2016-02-01

    In this paper, a novel texturing technology by means of electrodepositon is introduced. Textured surface covered with small bumps with the average size of 28 μm in diameter and 10 μm in height was fabricated. The trough around the bumps acts as the pocket to trap the debris. The nitrogen implantation was used to enhance the tribological properties of textured surfaces. The effects of implanted energy and dose on the structures of coating and tribological performances of textured surfaces were studied. The results show that the formation of Cr2N or CrN depends on the implanted dose. After nitrogen ion implantation, the friction coefficient of textured surface reduced and the wear resistance of textured surface was improved. The wear resistance enhances with increase of implanted dose, and has little to do with implanted energy.

  12. Fabrication and characterization of a co-planar detector in diamond for low energy single ion implantation

    NASA Astrophysics Data System (ADS)

    Abraham, J. B. S.; Aguirre, B. A.; Pacheco, J. L.; Vizkelethy, G.; Bielejec, E.

    2016-08-01

    We demonstrate low energy single ion detection using a co-planar detector fabricated on a diamond substrate and characterized by ion beam induced charge collection. Histograms are taken with low fluence ion pulses illustrating quantized ion detection down to a single ion with a signal-to-noise ratio of approximately 10. We anticipate that this detection technique can serve as a basis to optimize the yield of single color centers in diamond. The ability to count ions into a diamond substrate is expected to reduce the uncertainty in the yield of color center formation by removing Poisson statistics from the implantation process.

  13. Application of a pulsed, RF-driven, multicusp source for low energy plasma immersion ion implantation

    SciTech Connect

    Wengrow, A.B.; Leung, K.N.; Perkins, L.T.; Pickard, D.S.; Rickard, M.; Williams, M.D.; Tucker, M.

    1996-06-01

    The multicusp ion source can produce large volumes of uniform, quiescent, high density plasmas. A plasma chamber suited for plasma immersion ion implantation (PIII) was readily made. Conventional PIII pulses the bias voltage applied to the substrate which is immersed in a CW mode plasma. Here, a method by which the plasma itself is pulsed was developed. Typically pulse lengths of 500 {mu}s are used and are much shorter than that of the substrate voltage pulse (5-15 ms). This approach, together with low gas pressures and low bias voltages, permits the constant energy implantation of an entire wafer simultaneously without glow discharge. Results show that this process can yield implant currents of up to 2.5 mA/cm{sup 2}; thus very short implant times can be achieved. Uniformity of the ion flux is also discussed. As this method can be scaled to any dimension, it can be made to handle any size wafer.

  14. Development of Linear Mode Detection for Top-down Ion Implantation of Low Energy Sb Donors

    NASA Astrophysics Data System (ADS)

    Pacheco, Jose; Singh, Meenakshi; Bielejec, Edward; Lilly, Michael; Carroll, Malcolm

    2015-03-01

    Fabrication of donor spin qubits for quantum computing applications requires deterministic control over the number of implanted donors and the spatial accuracy to within which these can be placed. We present an ion implantation and detection technique that allows us to deterministically implant a single Sb ion (donor) with a resulting volumetric distribution of <10 nm. This donor distribution is accomplished by implanting 30keV Sb into Si which yields a longitudinal straggle of <10 nm and combined with a <50 nm spot size using the Sandia NanoImplanter (nI). The ion beam induced charge signal is collected using a MOS detector that is integrated with a Si quantum dot for transport measurments. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE Office of Basic Energy Sciences user facility. The work was supported by Sandia National Laboratories Directed Research and Development Program. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the U. S. Department of Energy under Contract No. DE-AC04-94AL85000.

  15. Research on the Distant Hybrids of Wheat Obtained via Low-Energy Ion-Beam Implantation

    NASA Astrophysics Data System (ADS)

    Chang, Shouwei; Cheng, Yuhong; Qin, Guangyong; Su, Mingjie

    2003-06-01

    The whole DNA of soybean was implanted into four varieties of wheat of Zhongyu 5, Huaiyin 9628, Wenyou 1, Jimai 5 respectively via ion-beam mediation. There were 5 plants obtained whose protein content was higher than 18.5%, the highest one was 21.44%. There were 3 plants obtained whose protein content was lower than 11.5%, the lowest one was 10.96%. We can see that the whole DNA of soybean transformed into wheat via ion beam implantation can induce the increase in wheat protein content dramatically. The result also shows that the transformation efficiency of different gene types of wheat receptor varies greatly that the implanting time has a certain effect on the efficiency of transformation.

  16. Study of the amorphization of surface silicon layers implanted by low-energy helium ions

    NASA Astrophysics Data System (ADS)

    Lomov, A. A.; Myakon'kikh, A. V.; Oreshko, A. P.; Shemukhin, A. A.

    2016-03-01

    The structural changes in surface layers of Si(001) substrates subjected to plasma-immersion implantation by (2-5)-keV helium ions to a dose of D = 6 × 1015-5 × 1017 cm-2 have been studied by highresolution X-ray diffraction, Rutherford backscattering, and spectral ellipsometry. It is found that the joint application of these methods makes it possible to determine the density depth distribution ρ( z) in an implanted layer, its phase state, and elemental composition. Treatment of silicon substrates in helium plasma to doses of 6 × 1016 cm-2 leads to the formation of a 20- to 30-nm-thick amorphized surface layer with a density close to the silicon density. An increase in the helium dose causes the formation of an internal porous layer.

  17. Atomistic simulations of tungsten surface evolution under low-energy neon implantation

    NASA Astrophysics Data System (ADS)

    Backman, Marie; Hammond, Karl D.; Sefta, Faiza; Wirth, Brian D.

    2016-04-01

    Tungsten is a candidate material for the divertor of fusion reactors, where it will be subject to a high flux of particles coming from the fusion plasma as well as a significant heat load. Under helium plasma exposure in fusion-reactor-like conditions, a nanostructured morphology is known to form on the tungsten surface in certain temperature and incident energy ranges, although the formation mechanism is not fully established. A recent experimental study (Yajima et al 2013 Plasma Sci. Technol. 15 282-6) using neon or argon exposure did not produce similar nanostructure. This article presents molecular dynamics simulations of neon implantation in tungsten aimed at investigating the surface evolution and elucidating the role of noble gas mass in fuzz formation. In contrast to helium, neon impacts can sputter both tungsten and previously implanted neon atoms. The shorter range of neon ions, along with sputtering, limit the formation of large bubbles and likely prevents nanostructure formation.

  18. Inducing phase transitions of T-like BiFeO3 films by low-energy He implantation

    NASA Astrophysics Data System (ADS)

    Herklotz, Andreas; Beekman, Christianne; Rus, Stefania Florina; Ivanov, Ilia; Balke, Nina; Ward, Thomas Zac

    Ferroelectric phase transitions of BiFeO3 are found to be controllable through the application of single axis, out-of-plane strain. Low-energy He implantation has been deployed to induce out-of-plane strain in T-like BFO films, while the compressive in-plane strain due to the coherent growth on LaAlO3 substrates remains fixed. Our data shows that He implantation triggers a MC -MA - T phase sequence of the T polymorph that is identical to structural changes that are induced with increasing temperature. Mixed phases nanodomains phases are gradually suppressed and disappear above a certain He doping level. Our data shows that the ferroelectric and optical properties of BiFeO3 films critically depend on the He doping level. Thus, the results demonstrates that He implantation can be used as an intriguing approach to study lines in the rich phase space of BFO films that can't be accessed by simple heteroepitaxy. This effort was wholly supported by the US Department of Energy (DOE), Office of Basic Energy Sciences (BES), Materials Sciences and Engineering Division, with user projects supported at ORNL's Center for Nanophase Materials Research (CNMS) which is also sponsored by DOE-BES.

  19. Low flux and low energy helium ion implantation into tungsten using a dedicated plasma source

    NASA Astrophysics Data System (ADS)

    Pentecoste, Lucile; Thomann, Anne-Lise; Melhem, Amer; Caillard, Amael; Cuynet, Stéphane; Lecas, Thomas; Brault, Pascal; Desgardin, Pierre; Barthe, Marie-France

    2016-09-01

    The aim of this work is to investigate the first stages of defect formation in tungsten (W) due to the accumulation of helium (He) atoms inside the crystal lattice. To reach the required implantation conditions, i.e. low He ion fluxes (1011-1014 ions.cm2.s-1) and kinetic energies below the W atom displacement threshold (about 500 eV for He+), an ICP source has been designed and connected to a diffusion chamber. Implantation conditions have been characterized by means of complementary diagnostics modified for measurements in this very low density helium plasma. It was shown that lowest ion fluxes could only be reached for the discharge working in capacitive mode either in α or γ regime. Special attention was paid to control the energy gained by the ions by acceleration through the sheath at the direct current biased substrate. At very low helium pressure, in α regime, a broad ion energy distribution function was evidenced, whereas a peak centered on the potential difference between the plasma and the biased substrate was found at higher pressures in the γ mode. Polycrystalline tungsten samples were exposed to the helium plasma in both regimes of the discharge and characterized by positron annihilation spectroscopy in order to detect the formed vacancy defects. It was found that W vacancies are able to be formed just by helium accumulation and that the same final implanted state is reached, whatever the operating mode of the capacitive discharge.

  20. Formation of Si/SiC multilayers by low-energy ion implantation and thermal annealing

    NASA Astrophysics Data System (ADS)

    Dobrovolskiy, S.; Yakshin, A. E.; Tichelaar, F. D.; Verhoeven, J.; Louis, E.; Bijkerk, F.

    2010-03-01

    Si/SiC multilayer systems for XUV reflection optics with a periodicity of 10-20 nm were produced by sequential deposition of Si and implantation of 1 keV CHx+ ions. Only about 3% of the implanted carbon was transferred into the SiC, with a thin, 0.5-1 nm, buried SiC layer being formed. We investigated the effect of thermal annealing on further completion of the carbide layer. For the annealing we used a vacuum furnace, a rapid thermal annealing system in argon atmosphere, and a scanning e-beam, for different temperatures, heating rates, and annealing durations. Annealing to a temperature as low as 600 °C resulted in the formation of a 4.5 nm smooth, amorphous carbide layer in the carbon-implanted region. However, annealing at a higher temperature, 1000 °C, lead to the formation of a rough poly-crystalline carbide layer. The multilayers were characterized by grazing incidence X-ray reflectometry and cross section TEM.

  1. Surface nanostructures on low energy Zn ion implanted crystalline Si and their thermal evolution at different atmospheres

    NASA Astrophysics Data System (ADS)

    Liu, Changlong; Zhao, Hang; Shen, Yanyan; Jia, Guangyi; Wang, Jun; Mu, Xiaoyu

    2014-05-01

    Cz n-type Si (1 0 0) wafers were implanted with 45 keV Zn ions at a fluence of 1.0 × 1017 ions/cm2. Formation of surface nanostructures, their structures and thermal evolution in different atmospheres have been studied. Our results clearly show that creation of surface nanostructures depends strongly on both annealing temperature and atmosphere. In nitrogen ambient, hemispherical nano-sized bumps could be effectively observed on the Zn-implanted Si surface after annealing at 600 °C, and their sizes increase with the annealing temperature up to 800 °C. However, in the oxygen ambient, hemispherical nano-sized bumps created at 600 °C could be transferred to winding patterns after 800 °C annealing. The results from X-ray photoelectron spectroscopy and grazing X-ray diffraction measurements reveal production of Zn NPs near the Si surface in as-implanted state. The thermal growth and transformation of such NPs during annealing contribute to formation and evolution of the observed surface nanostructures.

  2. The damaging effects of nitrogen ion beam implantation on upland cotton ( Gossypium hirsutum L.) pollen grains

    NASA Astrophysics Data System (ADS)

    Yu, Yanjie; Wu, Lijun; Wu, Yuejin; Wang, Qingya; Tang, Canming

    2008-09-01

    With the aim to study the effects of an ion beam on plant cells, upland cotton (Gossypium hirsutum L.) cultivar "Sumian 22" pollen grains were irradiated in vacuum (7.8 × 10-3 Pa) by low-energy nitrogen ions with an energy of 20 keV at various fluences ranging from 0.26 × 1016 to 0.78 × 1016 N+/cm2. The irradiation effects on pollen grains were tested, considering the ultrastructural changes in the exine and interior walls of pollen grains, their germination rate, the growth speed of the pollen tubes in the style, fertilization and boll development after the pistils were pollinated by the pollen grains which had been implanted with nitrogen ions. Nitrogen ions entered the pollen grains by etching and penetrating the exine and interior walls and destroying cell structures. A greater percentage of the pollen grains were destroyed as the fluence of N+ ions increased. Obviously, the nitrogen ion beam penetrated the exine and interior walls of the pollen grains and produced holes of different sizes. As the ion fluence increased, the amount and the density of pollen grain inclusions decreased and the size of the lacuna and starch granules increased. Pollen grain germination rates decreased with increasing ion fluence. The number of pollen tubes in the style declined with increased ion implantation into pollen grains, but the growth speed of the tubes did not change. All of the pollen tubes reached the end of the style at 13 h after pollination. This result was consistent with that of the control. Also, the weight and the diameter of the ovary decreased and shortened with increased ion beam implantation fluence. No evident change in the fecundation time of the ovule was observed. These results indicate that nitrogen ions can enter pollen grains and cause a series of biological changes in pollen grains of upland cotton.

  3. Implantation of nitrogen, carbon, and phosphorus ions into metals

    SciTech Connect

    Guseva, M.I.; Gordeeva, G.V.

    1987-01-01

    The application of ion implantation for alloying offers a unique opportunity to modify the chemical composition, phase constitution, and microstructure of the surface layers of metals. The authors studied ion implantation of nitrogen and carbon into the surface layers of metallic targets. The phase composition of the implanted layers obtained on the Kh18N10T stainless steel, the refractory molybdenum alloy TsM-6, niobium, and nickel was determined according to the conventional method of recording the x-ray diffraction pattern of the specimens using monochromatic FeK/sub alpha/-radiation on a DRON-2,0 diffractometer. The targets were bombarded at room temperature in an ILU-3 ion accelerator. The implantation of metalloid ions was also conducted with the targets being bombarded with 100-keV phosphorus ions and 40-keV carbon ions.

  4. Making AlN(x) Tunnel Barriers Using a Low-Energy Nitrogen-Ion Beam

    NASA Technical Reports Server (NTRS)

    Kaul, Anupama; Kleinsasser, Alan; Bumble, Bruce; LeDuc, Henry; Lee, Karen

    2005-01-01

    A technique based on accelerating positive nitrogen ions onto an aluminum layer has been demonstrated to be effective in forming thin (<2 nm thick) layers of aluminum nitride (AlN(x)) for use as tunnel barriers in Nb/Al-AlN(x)/Nb superconductor/insulator/ superconductor (SIS) Josephson junctions. AlN(x) is the present material of choice for tunnel barriers because, to a degree greater than that of any other suitable material, it offers the required combination of low leakage current at high current density and greater thermal stability. While ultra-thin AlN films with good thickness and stoichiometry control are easily formed using techniques such as reactive molecular beam epitaxy and chemical vapor deposition, growth temperatures of 900 C are necessary for the dissociative adsorption of nitrogen from either nitrogen (N2) or ammonia (NH3). These growth temperatures are prohibitively high for the formation of tunnel barriers on Nb films because interfacial reactions at temperatures as low as 200 to 300 C degrade device properties. Heretofore, deposition by reactive sputtering and nitridation of thin Al layers with DC and RF nitrogen plasmas have been successfully used to form AlN barriers in SIS junctions. However, precise control over critical current density Jc has proven to be a challenge, as is attaining adequate process reproducibility from system to system. The present ion-beam technique is an alternative to the plasma or reactive sputtering techniques as it provides a highly controlled arrival of reactive species, independent of the electrical conditions of the substrate or vacuum chamber. Independent and accurate control of parameters such as ion energy, flux, species, and direction promises more precise control of film characteristics such as stoichiometry and thickness than is the case with typical plasma processes. In particular, the background pressure during ion-beam nitride growth is 2 or 3 orders of magnitude lower, minimizing the formation of

  5. Gene expression profiles in promoted-growth rice seedlings that germinated from the seeds implanted by low-energy N+ beam

    PubMed Central

    Ya, Huiyuan; Chen, Qiufang; Wang, Weidong; Chen, Wanguang; Qin, Guangyong; Jiao, Zhen

    2012-01-01

    The stimulation effect that some beneficial agronomic qualities have exhibited in present-generation plants have also been observed due to ion implantation on plants. However, there is relatively little knowledge regarding the molecular mechanism of the stimulation effects of ion-beam implantation. In order to extend our current knowledge about the functional genes related to this stimulation effect, we have reported a comprehensive microarray analysis of the transcriptome features of the promoted-growth rice seedlings germinating from seeds implanted by a low-energy N+ beam. The results showed that 351 up-regulated transcripts and 470 down-regulated transcripts, including signaling proteins, kinases, plant hormones, transposable elements, transcription factors, non-coding protein RNA (including miRNA), secondary metabolites, resistance proteins, peroxidase and chromatin modification, are all involved in the stimulating effects of ion-beam implantation. The divergences of the functional catalog between the vacuum and ion implantation suggest that ion implantation is the principle cause of the ion-beam implantation biological effects, and revealed the complex molecular networks required to adapt to ion-beam implantation stress in plants, including enhanced transposition of transposable elements, promoted ABA biosynthesis and changes in chromatin modification. Our data will extend the current understanding of the molecular mechanisms and gene regulation of stimulation effects. Further research on the candidates reported in this study should provide new insights into the molecular mechanisms of biological effects induced by ion-beam implantation. PMID:22843621

  6. Annealing Behavior of Ion-implanted Nitrogen in D9 Steel

    SciTech Connect

    Arunkumar, J.; David, C.; Nair, K. G. M.; Panigrahi, B. K.; Magudapathy, P.; Kennedy, John

    2011-07-15

    Nitrogen isotope N{sup 15} was implanted at the sub-surface of D9 steel. The resonance nuclear reaction analysis was used to probe the implanted nitrogen as a function of depth. The as-implanted D9 sample was isochronally annealed and by observing the broadening of nitrogen depth profile at various annealing junctures, activation energy for nitrogen diffusion in steel was deduced.

  7. Sub-5 nm graphene nanopore fabrication by nitrogen ion etching induced by a low-energy electron beam

    NASA Astrophysics Data System (ADS)

    Fox, Daniel S.; Maguire, Pierce; Zhou, Yangbo; Rodenburg, Cornelia; O’Neill, Arlene; Coleman, Jonathan N.; Zhang, Hongzhou

    2016-05-01

    A flexible and efficient method to fabricate nanopores in graphene has been developed. A focused, low-energy (5 keV) electron beam was used to locally activate etching of a graphene surface in a low pressure (0.3 Pa) N2 environment. Nanopores with sub-5 nm diameters were fabricated. The lattice structure of the graphene was observed to recover within 20 nm of the nanopore edge. Nanopore growth rates were investigated systematically. The effects of nitrogen pressure, electron beam dwell time and beam current were characterised in order to understand the etching mechanism and enable optimisation of the etching parameters. A model was developed which describes how the diffusion of ionised nitrogen affects the nanopore growth rate. Etching of other two-dimensional materials was attempted as demonstrated with MoS2. The lack of etching observed supports our model of a chemical reaction-based mechanism. The understanding of the etching mechanism will allow more materials to be etched by selection of an appropriate ion species.

  8. Sub-5 nm graphene nanopore fabrication by nitrogen ion etching induced by a low-energy electron beam.

    PubMed

    Fox, Daniel S; Maguire, Pierce; Zhou, Yangbo; Rodenburg, Cornelia; O'Neill, Arlene; Coleman, Jonathan N; Zhang, Hongzhou

    2016-05-13

    A flexible and efficient method to fabricate nanopores in graphene has been developed. A focused, low-energy (5 keV) electron beam was used to locally activate etching of a graphene surface in a low pressure (0.3 Pa) N2 environment. Nanopores with sub-5 nm diameters were fabricated. The lattice structure of the graphene was observed to recover within 20 nm of the nanopore edge. Nanopore growth rates were investigated systematically. The effects of nitrogen pressure, electron beam dwell time and beam current were characterised in order to understand the etching mechanism and enable optimisation of the etching parameters. A model was developed which describes how the diffusion of ionised nitrogen affects the nanopore growth rate. Etching of other two-dimensional materials was attempted as demonstrated with MoS2. The lack of etching observed supports our model of a chemical reaction-based mechanism. The understanding of the etching mechanism will allow more materials to be etched by selection of an appropriate ion species. PMID:27040079

  9. Impact of the end of range damage from low energy Ge preamorphizing implants on the thermal stability of shallow boron profiles

    SciTech Connect

    Camillo-Castillo, R.A.; Law, M.E.; Jones, K.S.

    2004-11-01

    A fundamental understanding of the effect of scaling amorphous layers on the thermal stability of active concentrations is required for the formation of ultrashallow junctions. A study on the influence of boron on the evolution of the end of range defects for samples containing shallow amorphous layers formed by low energy germanium implants is conducted. Czochralski grown (100) silicon wafers are preamorphized with 1x10{sup 15} cm{sup -2}, 10 keV Ge{sup +} and subsequently implanted with 1x10{sup 15} cm{sup -2}, 1 keV B{sup +} such that high boron levels are attained in the end of range region. A sequence of anneals are performed at 750 deg. C, under nitrogen ambient for times ranging from 1 s to 6 h and the end of range defect evolution is imaged via plan-view transmission electron microscopy (TEM). Defect analyses are conducted utilizing quantitative TEM which indicates substantial differences in the defect evolution for samples with boron in the end of range. The extended defects observed are very unstable and undergo a fast dissolution. In contrast, stable defects are observed in the experimental control in which the evolution follows an Ostwald ripening behavior. Secondary ion mass spectroscopy analyses confirm the ephemeral nature of the defects observed and also demonstrates drastic reductions in interstitial supersaturation. In addition, uphill-type diffusion is observed to occur for a short time frame, which emphasizes a transient interstitial supersaturation. Correlation of this data with sheet resistance and active dose measurements conducted on a Hall measurement system strongly indicates the formation of boron interstitial clusters. The high boron concentrations and supersaturation levels attained at the anneal temperature enables the cluster formation. An estimate of the boron concentrations trapped in the clusters is determined from the active dose obtained from the Hall measurements and indicates concentrations much higher than those available in

  10. FeN foils by nitrogen ion-implantation

    SciTech Connect

    Jiang, Yanfeng; Wang, Jian-Ping; Al Mehedi, Md; Fu, Engang; Wang, Yongqiang

    2014-05-07

    Iron nitride samples in foil shape (free standing, 500 nm in thickness) were prepared by a nitrogen ion-implantation method. To facilitate phase transformation, the samples were bonded on the substrate followed by a post-annealing step. By using two different substrates, single crystal Si and GaAs, structural and magnetic properties of iron nitride foil samples prepared with different nitrogen ion fluences were characterized. α″-Fe{sub 16}N{sub 2} phase in iron nitride foil samples was obtained and confirmed by the proposed approach. A hard magnetic property with coercivity up to 780 Oe was achieved for the FeN foil samples bonded on Si substrate. The feasibility of using nitrogen ion implantation techniques to prepare FeN foil samples up to 500 nm thickness with a stable martensitic phase under high ion fluences has been demonstrated. A possible mechanism was proposed to explain this result. This proposed method could potentially be an alternative route to prepare rare-earth-free FeN bulk magnets by stacking and pressing multiple free-standing thick α″-Fe{sub 16}N{sub 2} foils together.

  11. Enhanced surface hardness in nitrogen-implanted silicon carbide

    SciTech Connect

    Uslu, C.; Lee, D.H.; Berta, Y.

    1995-06-01

    Preliminary studies have been performed on the feasibility of carbon-silicon nitride formation ({beta}-Si{sub 1.5}C{sub 1.5}N{sub 4}, the homologue of equilibrium {beta}-Si{sub 3}N{sub 4} or hypothetical {beta}-C{sub 3}N{sub 4}) by high dose N{sup +}-implantation into polycrystalline {beta}-SiC (cubic). Thin films were formed using 100 keV implantations with varying ion doses in the range from 1.1 x 10{sup 17} to 27.1 x 10{sup 17} N/cm{sup 2}, and target temperatures between -196{degrees}C and 980{degrees}C. X-ray diffraction with a position-sensitive detector and cross-sectional transmission electron microscopy revealed that the as-implanted surfaces (up to 860{degrees}C) contained {approximately}0.1 {mu}m thick buried amorphous layers. Rutherford backscattering spectroscopy showed that the peak concentration of nitrogen saturated up to approximately 54 at. % with increasing doses, suggesting formation of a new phase. Implantation to doses of 1.1 x 10{sup 17} and 2.3 x 10{sup 17} N/cm{sup 2} at 980{degrees}C caused enhanced surface hardness compared to SiC.

  12. Properties of nitrogen implanted and electron beam annealed bulk ZnO

    SciTech Connect

    Kennedy, J.; Carder, D. A.; Markwitz, A.; Reeves, R. J.

    2010-05-15

    The optical properties of bulk ZnO ion implanted with nitrogen ions, at an energy of 23 keV have been studied as a function of implantation fluence and electron beam (EB) annealing conditions. Nuclear reaction analysis and Raman results have revealed the implanted N concentration and its structural changes with respect to various nitrogen ion fluences. The optical properties of nitrogen implanted bulk ZnO were investigated by low temperature photoluminescence measurements. An enhanced peak at 3.235 eV has been attributed to donor-accepter pair (DAP) emission involving the implanted N acceptor in ZnO. The emission near 3.3085 eV is attributed to a free electron to acceptor transition. We also report a broad band emission feature at {approx}3.09 eV in the nitrogen implanted with 1-2x10{sup 15} ions cm{sup -2} and EB annealed at 800-900 deg. C. This is assigned to a thermally activated nitrogen acceptor transition as it is unique only to nitrogen implanted samples. An ionization energy of 377 meV indicates that this line may correspond to a significantly less shallow acceptor level. In addition an increase in the intensity and dominance of this DAP line in nitrogen implanted samples over the other acceptor transitions was observed with increasing annealing time and temperatures. It is shown that EB annealing offers a method of enhanced nitrogen activation when compared to a more conventional furnace approach.

  13. Amorphous Ge quantum dots embedded in SiO{sub 2} formed by low energy ion implantation

    SciTech Connect

    Zhao, J. P.; Huang, D. X.; Jacobson, A. J.; Chen, Z. Y.; Makarenkov, B.; Chu, W. K.; Bahrim, B.; Rabalais, J. W.

    2008-06-15

    Under ultrahigh vacuum conditions, extremely small Ge nanodots embedded in SiO{sub 2}, i.e., Ge-SiO{sub 2} quantum dot composites, have been formed by ion implantation of {sup 74}Ge{sup +} isotope into (0001) Z-cut quartz at a low kinetic energy of 9 keV using varying implantation temperatures. Transmission electron microscopy (TEM) images and micro-Raman scattering show that amorphous Ge nanodots are formed at all temperatures. The formation of amorphous Ge nanodots is different from reported crystalline Ge nanodot formation by high energy ion implantation followed by a necessary high temperature annealing process. At room temperature, a confined spatial distribution of the amorphous Ge nanodots can be obtained. Ge inward diffusion was found to be significantly enhanced by a synergetic effect of high implantation temperature and preferential sputtering of surface oxygen, which induced a much wider and deeper Ge nanodot distribution at elevated implantation temperature. The bimodal size distribution that is often observed in high energy implantation was not observed in the present study. Cross-sectional TEM observation and the depth profile of Ge atoms in SiO{sub 2} obtained from x-ray photoelectron spectra revealed a critical Ge concentration for observable amorphous nanodot formation. The mechanism of formation of amorphous Ge nanodots and the change in spatial distribution with implantation temperature are discussed.

  14. Optical waveguides fabricated by nitrogen ion implantation in fused silica

    NASA Astrophysics Data System (ADS)

    Liu, Chun-Xiao; Fu, Li-Li; Zheng, Rui-Lin; Guo, Hai-Tao; Zhou, Zhi-Guang; Li, Wei-Nan; Lin, She-Bao; Wei, Wei

    2016-02-01

    We report on the fabrication of waveguides in fused silica using 4.5-MeV nitrogen ion implantation with a fluence of 5.0×1014 ions/cm2. The prism-coupling method was employed to measure the effective refractive indices of guiding modes at the wavelengths of 632.8 and 1539 nm. The effective refractive indices of the first few modes were higher than that of the substrate. The refractive index profiles at 632.8 and 1539 nm were reconstructed by the reflectivity calculation method. Positive index changes were induced in the waveguide layers. The end-face coupling method was used to measure the near-field light intensity distributions at the wavelength of 632.8 nm and the finite-difference beam propagation method was applied to simulate the guided mode profile at the wavelength of 1539 nm. The waveguide structures emerge as candidates for integrated photonic devices.

  15. Investigation of various phases of Fe-Si structures formed in Si by low energy Fe ion implantation

    NASA Astrophysics Data System (ADS)

    Lakshantha, Wickramaarachchige J.; Dhoubhadel, Mangal S.; Reinert, Tilo; McDaniel, Floyd D.; Rout, Bibhudutta

    2015-12-01

    The compositional phases of ion beam synthesized Fe-Si structures at two high fluences (0.50 × 1017 atoms/cm2 and 2.16 × 1017 atoms/cm2) were analyzed using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The distribution of Fe implanted in Si was simulated using a dynamic simulation code (TRIDYN) incorporating target sputtering effects. The Fe depth profiles in the Si matrix were confirmed with Rutherford backscattering spectrometry (RBS) and XPS depth profiling using Ar-ion etching. Based on XPS binding energy shift and spectral asymmetry, the distribution of stable Fe-Si phases in the substrate was analyzed as a function of depth. Results indicate Fe implantation with a fluence of 0.50 × 1017 atoms/cm2 and subsequent thermal annealing produce mainly the β-FeSi2 phase in the whole thickness of the implanted region. But for the samples with a higher fluence Fe implantation, multiple phases are formed. Significant amount of Fe3Si phase are found at depth intervals of 14 nm and 28 nm from the surface. Initially, as-implanted samples show amorphous Fe3Si formation and further thermal annealing at 500 °C for 60 min formed crystalline Fe3Si structures at the same depth intervals. In addition, thermal annealing at 800 °C for 60 min restructures the Fe3Si clusters to form FeSi2 and FeSi phases.

  16. Structural, mechanical and optical properties of nitrogen-implanted titanium at different pulse frequency

    NASA Astrophysics Data System (ADS)

    Raaif, Mohamed; Mohamed, Sodky H.; Abd El-Rahman, Ahmed M.; Kolitsch, Andreas

    2013-04-01

    Plasma-immersion ion implantation (PIII) is a potent method to obtain hard and wear-resistant surface on Ti by nitrogen implantation. This presentation is one part of a sequence of experiments to optimize the microstructure and physical properties of TiN through adapting the plasma-processing parameters. In this work, nitrogen ions were implanted into samples of pure Ti at different nitrogen pulse frequency without using any external source of heating. The nitrogen-implanted surfaces were characterized by X-ray diffraction (XRD), Auger electron spectroscopy (AES), optical microscope, nano-indentation technique, ball-on-disk type tribometer, surface profilemeter, Tafel polarization technique for corrosion performance and ellipsometry. The outcomes show that, nitrogen PIII is an effectual method for nitriding titanium and nitrogen pulse frequency affected the microstructure and physical properties of the treated Ti. X-ray diffraction depicted the formation of α-Ti (N) and the cubic TiN after implanting titanium by nitrogen and the thickness of the nitrided layer increased as the nitrogen pulse frequency increased. The wear and corrosion resistance of the nitrogen-implanted titanium are improved and the friction coefficient decreased from nearly 0.8 for the un-implanted titanium to 0.3 for the implanted titanium, this ascribed to the formation of the titanium nitrided phases. Ellipsometric measurements were carried out on the PIII titanium samples at different nitrogen pulse frequency. The ellipsometric measurements show that, the thickness of the nitrided layer and surface roughness increased while the refractive index decreased with increasing nitrogen pulse frequency.

  17. An Auger Sputter Profiling Study of Nitrogen and Oxygen Ion Implantations in Two Titanium Alloys

    SciTech Connect

    Barton, B. D., Pope, L. E., Wittberg, T. N.

    1989-07-31

    Samples of two titanium alloys, Ti-6A1-4V and Ti-15V-3Cr-3Sn-3A1, were ion implanted with a combination of nitrogen (N+) and oxygen (O+). For each alloy, implantation parameters were chosen to give implanted nitrogen concentrations of approximately 10 or 50 atomic percent, from a depth of 100 nanometers to a depth of 400 nanometers. In all but one case, dual energy (200 keV and 90 keV) implantations of nitrogen were used to give a relatively uniform nitrogen concentration to a depth of 300 nanometers. In each case, oxygen was implanted at 35 keV, following the nitrogen implantation, to give an oxygen-enriched region near the surface. The implanted samples were then examined by Auger electron spectroscopy (AES) combined with argon ion sputtering. In order to determine the stoichiometry of the nitrogen implanted regions, it was necessary to determine the N (KVV) contribution to the overlapping N (KVV) and Ti (LMM) Auger transitions. It was also necessary to correct for the ion-bombardment-induced compositional changes which have been described in an earlier study of titanium nitride thin films. The corrected AES depth profiles were in good agreement with theoretical predictions.

  18. Fabrication and characterization of a co-planar detector in diamond for low energy single ion implantation

    DOE PAGESBeta

    Abraham, John Bishoy Sam; Pacheco, Jose L.; Aguirre, Brandon Adrian; Vizkelethy, Gyorgy; Bielejec, Edward S.

    2016-05-01

    We demonstrate low energy single ion detection using a co-planar detector fabricated on a diamond substrate and characterized by ion beam induced charge collection. Histograms are taken with low fluence ion pulses illustrating quantized ion detection down to a single ion with a signal-to-noise ratio of approximately 10. We anticipate that this detection technique can serve as a basis to optimize the yield of single color centers in diamond. In conclusion, the ability to count ions into a diamond substrate is expected to reduce the uncertainty in the yield of color center formation by removing Poisson statistics from the implantationmore » process.« less

  19. Two-dimensional profiling of large tilt angle, low energy boron implanted structure using secondary-ion mass spectrometry

    SciTech Connect

    Cooke, G.A.; Pearson, P.; Gibbons, R.; Dowsett, M.G.; Hill, C.

    1996-01-01

    Experimentally determined two-dimensional dopant maps of implants into semiconductors are required for the calibration and verification of process simulation tools used in very large scale integrated (VLSI) circuit design. Direct measurement with currently available techniques is not possible owing to the physical size of the areas in question. Using a specially fabricated structure and a modified secondary-ion mass spectroscopy instrument, it has been possible to measure profiles with high spatial resolution and sensitivity. In this article we present the results of an investigation of a complex boron implant into silicon, as used in advanced VLSI {ital P}-type metal{endash}oxide{endash}semiconductor source{endash}drain regions, and compare it with results from process simulators. {copyright} {ital 1996 American Vacuum Society}

  20. Size saturation in low energy ion beam synthesized nanoparticles in silica glass: 50 keV Ag{sup -} ions implantation, a case study

    SciTech Connect

    Kuiri, P. K.

    2010-09-15

    Fluence-dependent formation of Ag nanoparticles (NPs) in silica glass by 50 keV Ag{sup -} ions implantation has been studied. Samples implanted with fluences of 2x10{sup 16} ions cm{sup -2} and above are found to show an absorption band at around 410 nm, corresponding to the surface plasmon resonance (SPR) of the Ag NPs in silica glass. An increase in SPR peak intensity with increase in fluence has been observed up to a fluence of 7x10{sup 16} ions cm{sup -2} (F7), after which the absorption intensity shows a saturation. Simulations of the optical absorption spectra also indicated an increase in the absorption intensity and hence the size of the NPs with increase in fluence up to F7, beyond which NP size is seen to saturate. The saturation of fluence and the SPR intensity (or NP size) have been explained as coming due to a break up of larger Ag NPs formed near the surface by displacement spikes induced by subsequently incident Ag ions against their regrowth from the movement of Ag atoms toward the surface and their sputtering loss. Further, we have compared our observations with the earlier data on saturation of fluence and size of NPs in cases of Au and Zn, and concluded that the saturation of both fluence and NP size are general phenomena for low energy high fluence metal ion implantation.

  1. Few-Layer MoS₂ p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation.

    PubMed

    Nipane, Ankur; Karmakar, Debjani; Kaushik, Naveen; Karande, Shruti; Lodha, Saurabh

    2016-02-23

    P-type doping of MoS2 has proved to be a significant bottleneck in the realization of fundamental devices such as p-n junction diodes and p-type transistors due to its intrinsic n-type behavior. We report a CMOS compatible, controllable and area selective phosphorus plasma immersion ion implantation (PIII) process for p-type doping of MoS2. Physical characterization using SIMS, AFM, XRD and Raman techniques was used to identify process conditions with reduced lattice defects as well as low surface damage and etching, 4X lower than previous plasma based doping reports for MoS2. A wide range of nondegenerate to degenerate p-type doping is demonstrated in MoS2 field effect transistors exhibiting dominant hole transport. Nearly ideal and air stable, lateral homogeneous p-n junction diodes with a gate-tunable rectification ratio as high as 2 × 10(4) are demonstrated using area selective doping. Comparison of XPS data from unimplanted and implanted MoS2 layers shows a shift of 0.67 eV toward lower binding energies for Mo and S peaks indicating p-type doping. First-principles calculations using density functional theory techniques confirm p-type doping due to charge transfer originating from substitutional as well as physisorbed phosphorus in top few layers of MoS2. Pre-existing sulfur vacancies are shown to enhance the doping level significantly. PMID:26789206

  2. Nitrogen and aluminum implantation in high resistivity silicon carbide

    SciTech Connect

    Dwight, D.; Rao, M.V.; Holland, O.W.; Kelner, G.; Chi, P.H.; Kretchmer, J.; Ghezzo, M.

    1997-12-01

    In this article, the results on N and Al implantations into undoped high-resistance and vanadium doped semi-insulating bulk 6H-SiC are reported for the first time. The N implants were performed at 700{degree}C and the Al implants at 800{degree}C to create n- and p-type layers, respectively. For comparison, implants were performed into epitaxial layers at the above temperatures and, for N, also at room temperature. The implanted/annealed material was characterized by van der Pauw Hall, secondary ion mass spectrometry, and Rutherford backscattering (RBS) measurements. After annealing, the room temperature N implantation gave similar electrical and RBS results as the 700{degree}C implantation for a total implant dose of 8{times}10{sup 14}cm{sup {minus}2} which corresponds to a volume concentration of 2{times}10{sup 19}cm{sup {minus}3}. The Al implant redistributed in the bulk crystals during annealing, resulting in a shoulder formation at the tail of the implant profile. Lower implant activation was obtained in V-doped material compared to the undoped bulk and epitaxial layers, but the results were promising enough to use implantation technology for making planar high frequency devices in the bulk V-doped substrates, especially as the quality of the substrates continue to improve. {copyright} {ital 1997 American Institute of Physics.}

  3. Carbon, nitrogen, and oxygen ion implantation of stainless steel

    SciTech Connect

    Rej, D.J.; Gavrilov, N.V.; Emlin, D.

    1995-12-31

    Ion implantation experiments of C, N, and O into stainless steel have been performed, with beam-line and plasma source ion implantation methods. Acceleration voltages were varied between 27 and 50 kV, with pulsed ion current densities between 1 and 10 mA/cm{sup 2}. Implanted doses ranged from 0.5 to 3 {times} 10{sup 18}cm{sup -2}, while workpiece temperatures were maintained between 25 and 800 C. Implant concentration profiles, microstructure, and surface mechanical properties of the implanted materials are reported.

  4. Nano-welding and junction formation in hydrogen titanate nanowires by low-energy nitrogen ion irradiation.

    PubMed

    Dhal, Satyanarayan; Chatterjee, Shyamal; Sarkar, Subhrangsu; Tribedi, Lokesh C; Bapat, Rudheer; Ayyub, Pushan

    2015-06-12

    Crystalline hydrogen titanate (H2Ti3O7) nanowires were irradiated with N(+) ions of different energies and fluences. Scanning electron microscopy reveals that at relatively lower fluence the nanowires are bent and start to adhere strongly to one another as well as to the silicon substrate. At higher fluence, the nanowires show large-scale welding and form a network of mainly 'X' and 'Y' junctions. Transmission electron microscopy and Raman scattering studies confirm a high degree of amorphization of the nanowire surface after irradiation. We suggest that while ion-irradiation induced defect formation and dangling bonds may lead to chemical bonding between nanowires, the large scale nano-welding and junction network formation can be ascribed to localized surface melting due to heat spike. Our results demonstrate that low energy ion irradiation with suitable choice of fluence may provide an attractive route to the formation and manipulation of large-area nanowire-based devices. PMID:25990259

  5. Nano-welding and junction formation in hydrogen titanate nanowires by low-energy nitrogen ion irradiation

    NASA Astrophysics Data System (ADS)

    Dhal, Satyanarayan; Chatterjee, Shyamal; Sarkar, Subhrangsu; Tribedi, Lokesh C.; Bapat, Rudheer; Ayyub, Pushan

    2015-06-01

    Crystalline hydrogen titanate (H2Ti3O7) nanowires were irradiated with N+ ions of different energies and fluences. Scanning electron microscopy reveals that at relatively lower fluence the nanowires are bent and start to adhere strongly to one another as well as to the silicon substrate. At higher fluence, the nanowires show large-scale welding and form a network of mainly ‘X’ and ‘Y’ junctions. Transmission electron microscopy and Raman scattering studies confirm a high degree of amorphization of the nanowire surface after irradiation. We suggest that while ion-irradiation induced defect formation and dangling bonds may lead to chemical bonding between nanowires, the large scale nano-welding and junction network formation can be ascribed to localized surface melting due to heat spike. Our results demonstrate that low energy ion irradiation with suitable choice of fluence may provide an attractive route to the formation and manipulation of large-area nanowire-based devices.

  6. Nitrogen and boron ion implantation into electrodeposited hard chrome

    SciTech Connect

    Walter, K.C.; Tesmer, J.R.; Scarborough, W.K.; Woodring, J.S.; Nastasi, M.; Kern, K.T.

    1996-10-01

    Electrodeposited hard chrome was ion implanted with N alone, B alone, and a combination. Separate N and B implantation was done at 75 keV and incident doses of 2, 4, and 8x10{sup 17} at/cm{sup 2}. Samples with both N/B implants used 75 keV and incident dose levels of 4x10{sup 17} N- and B-at/cm{sup 2}. Beam-line system was used. Retained dose was measured using ion beam analysis, which indicated most of the incident dose was retained. Surface hardness, wear coefficient, and friction coefficient were determined by nanohardness indentation and pin-on-disk wear. At a depth of 50 nm, surface hardness increased from 18{+-}1 GPa (unimplanted) to a max of 23{+-}4 GPa for B implant and 26{+-}1 GPa for N implant. the wear coefficient was reduced by 1.3x to 7.4x, depending on implantation. N implant results in lower wear coefficients than B implant.

  7. Influence of Temperature on Nitrogen Ion Implantation of Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Zhao, Qing; Zheng, Yong-zhen; Mo, Zhi-tao; Tang, De-li; Tong, Hong-hui; Geng, Man

    2001-04-01

    In order to achieve increased layer thickness, and wearing resistance, enhanced ion implantation with nitrogen has been carried out at temperatures of 100, 200, 400, and 600°C with a dose of 4×1018 ions cm-2. Using the Plasma Source Ion Implantation (PSII) device, specimens of Ti6Al4V alloy were implanted at elevated temperatures, using the ion flux as the heating source. Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), x-ray Diffraction (XRD), micro-hardness measurements and pin-on-disk wearing tester were utilized to evaluate the surface property improvements. The thickness of the implanted layer increased by about an order of magnitude when the temperature was elevated from 100 to 600°C. Higher surface hardness and wearing resistance was also obtained in implantation under higher temperature. XRD image showed the presence of titanium nitrides on the implanted surface.

  8. The impact of implantation sequence on the characterization of n-MOSFET's with gate oxide grown on nitrogen-implanted Si substrate

    NASA Astrophysics Data System (ADS)

    Wu, You-Lin

    2002-08-01

    Both of the nitrogen implantation and threshold-voltage adjustment implantation introduce dopant atoms near the SiO 2/Si interface during the fabrication of n-channel metal-oxide-semiconductor field-effect transistor (n-MOSFET's) with gate oxide grown on nitrogen implanted silicon substrate. This work examined the impact of implantation sequence on the characterization of n-MOSFET's with gate oxide grown on nitrogen implanted silicon substrate. It is found that the sequence of nitrogen implantation and boron implantation affects both the electrical characteristics and hot-carrier properties of n-MOSFET's. It is found that no channel mobility degradation, less interface state density, lower subthreshold leakage current and better hot-carrier resistance can be achieved in the n-MOSFET's if the threshold-voltage adjustment implantation is performed after the nitrogen implantation during the gate oxide preparation. However lower channel mobility, higher interface state density, higher subthreshold leakage current and less hot-carrier resistance were observed if the implantation sequence was reversed.

  9. Investigation of nitrogen and carbon co-implantation under room temperature and cryo-condition

    NASA Astrophysics Data System (ADS)

    He, Yonggen; Wu, Bing; Yu, Guobin; Chen, Yong; Liu, Hailong; He, Youfeng; Dai, Haibo; Wu, Jingang; Zhang, David Wei; Lu, Junfeng; Xu, Jingrui; Guo, Baonian

    2012-11-01

    Co-implantation of non-dopant species is widely used in 65nm and beyond Complementary Metal-Oxide-Semiconductor (CMOS) technology node to meet ITRS ultra shallow junction roadmap and device performance requirement. With co-implantation, non-dopant species, such as Carbon (C), Fluorine (F) and Nitrogen (N), can either suppress doping diffusion or modify material property and improve device reliability. Cold implantation with wafer pedestal cooling to near -100°C is another hot topic in CMOS manufacture recently. It has obvious benefits, such as good amorphization performance, less end of range defect, less stress relaxation especially for e-SiGe formation. In the present work, different co-implantations with nitrogen and/or carbon were investigated for advanced NMOS Lightly Doped Drain (LDD) junction formation. The co-implantation was performed under room temperature or -100°C. It was found that C or C plus N co-implantations are very effective to suppress the diffusion of halo-implanted boron. Comparing with room temperature, the cryo-implantation under -100°C can get much better amorphization and less End of Range (EOR) defects, which result in reduced junction leakage and high activation as observed on blanket wafer and device wafers.

  10. A study of silicon-on-insulator structures formed by heavy-dose nitrogen implantation

    SciTech Connect

    Polchlopek, S.W.

    1991-01-01

    Silicon substrates were implanted with heavy doses of high-energy nitrogen. After implantation, the substrates underwent high-temperature annealing. The resulting substrates were studied in an effort to determine the processing parameters necessary to create the optimum-buried silicon nitride insulating layer. Atomic concentration depth profiles were obtained with the use of Auger Electron Spectroscopy. The van der Pauw technique was used to determine carrier Hall mobility, dopant activation, and sheet resistivity in the top layer. Buried-layer leakage was studied using both electron-beam-induced-current (EBIC) analysis and direct front-to-back current-voltage measurements. Implant parameters studied include dose, temperature, and energy. Annealing conditions studied include time and temperature. Samples implanted with lower doses of nitrogen (dose < 1.4 {times} 10{sup 18} cm{sup {minus}2}) possess very leaky buried layers. Higher-dose implants (dose = 1.4 {times} 10{sup 18} cm{sup {minus}2} or greater) produce substrates with good-quality buried dielectrics. It is discovered that very-high-dose nitrogen implantation is necessary to produce good-quality buried insulators.

  11. Magnetic properties and recording performances of patterned media fabricated by nitrogen ion implantation

    NASA Astrophysics Data System (ADS)

    Hinoue, Tatsuya; Ito, Kenichi; Hirayama, Yoshiyuki; Ono, Toshinori; Inaba, Hiroshi

    2011-04-01

    Nitrogen ion implantation was performed on CoCrPt-SiO2 perpendicular media with a resist mask to fabricate patterned media. Signal amplitude and autocorrelation signal-to-noise ratio of the preamble pattern were measured to evaluate the quality of the pattern fabricated by the ion implantation. The signal-to-noise ratio and the jitter were closely related to the saturation magnetization of the ion-implanted area. The remained magnetization of the ion-implanted area probably affects edge roughness of the magnetic pattern. Larger reduction of the saturation magnetization at the ion-implanted area is important for obtaining higher signal quality. Off-track profiles and 747 curves were measured for 76-nm-pitch discrete track fabricated by ion implantation. The results show that discrete track recording had advantages over recording on continuous magnetic film, which indicates that the fabricated patterns were successfully isolated. The nitrogen ion implantation was effective in fabricating isolated magnetic tracks or isolated magnetic dots for the patterned media.

  12. Friction wear and auger analysis of iron implanted with 1.5-MeV nitrogen ions

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Jones, W. R., Jr.

    1982-01-01

    The effect of implantation of 1.5-MeV nitrogen ions on the friction and wear characteristics of pure iron sliding against steel was studied in a pin-on disk apparatus. An implantation dose of 5 x 10 to the 17th power ions/sq cm was used. Small reductions in initial and steady-state wear rates were observed for nitrogen-implanted iron riders as compared with unimplanted controls. Auger electron spectroscopy revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 15 at. % at a depth of 8 x 10 to the -7th m. A similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration, thus giving no evidence for diffusion of nitrogen beyond the implanted range.

  13. Etch-stop behavior of buried layers formed by substoichiometric nitrogen ion implantation into silicon

    SciTech Connect

    Perez-Rodriguez, A.; Romano-Rodriguez, A.; Morante, J.R.; Acero, M.C. Esteve, J.; Montserrat, J.; El-Hassani, A.

    1996-03-01

    In this work the etch-stop behavior of buried layers formed by substoichiometric nitrogen ion implantation into silicon is studied as a function of the processing parameters, the implantation dose and temperature, and the presence of capping layers during implantation. Etching characteristics have been probed using tetramethylammonium hydroxide or KOH solutions for different times up to 6 h. Results show that, after annealing, the minimum dose required for the formation of an efficient etch-stop layer is about 4 {times} 10{sup 17} cm{sup {minus}2}, for an implantation energy of 75 keV. This is defined as a layer with an efficient etch selectivity in relation to Si of s {ge} 100. For larger implantation doses efficient etch selectivities larger than 100 are obtained. However, for these doses a considerable density of pits is observed in the etch-stop layer. These are related to the presence of nitrogen poor Si regions in the buried layer after annealing, due to a partial separation of silicon and silicon nitride phases during the annealing process. The influence of this separation of phases as well as nitrogen gettering in the buried layer on the etch-stop behavior is discussed as a function of the processing parameters.

  14. High density nitrogen-vacancy sensing surface created via He+ ion implantation of 12C diamond

    NASA Astrophysics Data System (ADS)

    Kleinsasser, Ed E.; Stanfield, Matthew M.; Banks, Jannel K. Q.; Zhu, Zhouyang; Li, Wen-Di; Acosta, Victor M.; Watanabe, Hideyuki; Itoh, Kohei M.; Fu, Kai-Mei C.

    2016-05-01

    We present a promising method for creating high-density ensembles of nitrogen-vacancy centers with narrow spin-resonances for high-sensitivity magnetic imaging. Practically, narrow spin-resonance linewidths substantially reduce the optical and RF power requirements for ensemble-based sensing. The method combines isotope purified diamond growth, in situ nitrogen doping, and helium ion implantation to realize a 100 nm-thick sensing surface. The obtained 1017 cm-3 nitrogen-vacancy density is only a factor of 10 less than the highest densities reported to date, with an observed 200 kHz spin resonance linewidth over 10 times narrower.

  15. Improvement of tribological behavior of a Ti Al Zr alloy by nitrogen ion implantation

    NASA Astrophysics Data System (ADS)

    Liu, Y. Z.; Zu, X. T.; He, X.; Qiu, S. Y.; Cao, J.; Huang, X. Q.

    2006-07-01

    Surface modification of a Ti-Al-Zr alloy with nitrogen implantation is considered as a method to improve its tribological properties especially wear and hardness. The implantation was carried out at fluences range from 1 × 10 16 to 1 × 10 17 ions/cm 2 and energy 65 keV. The tribological tests for the friction coefficients and wear were made on a pin-on-disk tribotester with the load 60 mN. Glancing angle X-ray diffraction (GAXRD) and X-ray photoelectron spectroscopy (XPS) analyses were performed to obtain surface characterization of the implanted sample. The unimplanted and implanted samples were also annealed at 500 °C in order to understand the influence of annealing on the tribological properties of Ti-Al-Zr. The hardness showed significant improvement at the higher fluence. After annealing at 500 °C, the friction coefficient exhibited a relative decrease for the nitrogen-implanted samples. In addition, the wear rates of the implanted samples exhibited a great decrease after annealing at 500 °C. Nature of the surface and reason for the variation and improvement in wear resistance were discussed in detail.

  16. Microstructure and oxidation behavior of high strength steel AISI 410 implanted with nitrogen ion

    NASA Astrophysics Data System (ADS)

    Bandriyana, Ismoyo, Agus Hadi; Sujitno, Tjipto; Dimyati, A.

    2016-04-01

    Surface treatment by implantation with nitrogen-ion was performed on the commercial feritic high strength steel AISI 410 which is termed for high temperature applications. The aim of this research was focused on the surface modification to improve its high temperature oxidation property in the early stages. Ion implantation was carried out at acceleration energy of 100 KeV and ion current 10 mA for 30, 60 and 90 minutes. The samples were subjected to the high temperature oxidation test by means of thermogravimetry in a magnetic suspension balance (MSB) at 500 °C for 5 hours. The scanning electron microscopy (SEM), X-ray diffraction spectrometry (XRD) and Vickers Hardness measurement were used for sample characterization. The formation of ferro-nitride phase after implantation did not occur, however a thin layer considered to contain nitrogen interstitials was detected. The oxidation of both samples before and after implantation followed parabolic kinetics indicating inward growth of oxide scale characteristically due to diffusion of oxygen anions towards matrix surface. After oxidation test relativelly stable oxide scales were observed. Oxidation rates decreased proportionally with the increasing of implantation time due to the formation of oxide layer which is considered to be effectiv inhibitor for the oxygen diffusion.

  17. Production and characterization of a nitrogen-implanted Fe standard to calibrate PIGE measurements

    SciTech Connect

    Rodrigues, C. L.; Silva, T. F.; Added, N.; Santos, H. C.; Tabacniks, M. H.

    2014-11-11

    Three calibration standard was produced by ion implantation of nitrogen in samples of Armco iron (99.7% iron). The samples was irradiated with nitrogen ion beams at several different energies (between 4 keV and 40 keV), and the ion doses were adjusted to obtain an uniform depth profile, using simulations with SRIM code. Two standards, one thick and other a foil (1.62mg/cm{sup 2}), was irradiated at same time with total nominal dose of 6.6×10{sup −16} atoms/cm{sup 2} distributed in a region of 100 nm in depth, with an average concentration of 9.0% nitrogen in iron. The third sample uses the same profile, but with a small dose, 1.1×10{sup −16} atoms/cm{sup 2} and average concentration of 1.5% nitrogen. The characterization of the implanted samples was done using RBS and NRA techniques to quantification of nitrogen.

  18. Nitrogen implantation effects on the chemical bonding and hardness of boron and boron nitride coatings

    SciTech Connect

    Anders, S; Felter, T; Hayes, J; Jankowski, A F; Patterson, R; Poker, D; Stamler, T

    1999-02-08

    Boron nitride (BN) coatings are deposited by the reactive sputtering of fully dense, boron (B) targets utilizing an argon-nitrogen (Ar-N{sub 2}) reactive gas mixture. Near-edge x-ray absorption fine structure analysis reveals features of chemical bonding in the B 1s photoabsorption spectrum. Hardness is measured at the film surface using nanoindentation. The BN coatings prepared at low, sputter gas pressure with substrate heating are found to have bonding characteristic of a defected hexagonal phase. The coatings are subjected to post-deposition nitrogen (N{sup +} and N{sub 2}{sup +}) implantation at different energies and current densities. The changes in film hardness attributed to the implantation can be correlated to changes observed in the B 1s NEXAFS spectra.

  19. Phase analysis of a nitrogen implanted CrNi 18.9 steel: A cems-study

    NASA Astrophysics Data System (ADS)

    Wagner, G.; Louis, T.; Leutenecker, R.; Gonser, U.

    1989-03-01

    Conversion Electron Mössbauer Spectroscopy (CEMS) has been used to study the modified structure of the near surface region of a nitrogen implanted austenitic X10CrNiTi18.9 steel. The implantation dose was varied from 2 to 8*1017N+/cm2 using an implantation temperature of 200°C and an ion energy of 100 keV. The (γ/a')-ratio in the near surface region of the untreated material was changed by electropolishing and mechanical polishing of the surface. The results of the spectra are discussed in terms of nitrogen solid solution in the case of low nitrogen doses and precipitation of Fe-nitrides (ɛ-Fe2N, ɛ-Fe2+xN) with increasing implantation dose. Phase transformations referring to the Fe-nitrides and the (γ/a')-ratio are observed with increasing nitrogen content.

  20. Short-range ordering of ion-implanted nitrogen atoms in SiC-graphene

    SciTech Connect

    Willke, P.; Druga, T.; Wenderoth, M.; Amani, J. A.; Weikert, S.; Hofsäss, H.; Thakur, S.; Maiti, K.

    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.

  1. Molecular dynamics simulations of shallow nitrogen and silicon implantation into diamond

    NASA Astrophysics Data System (ADS)

    Lehtinen, Ossi; Naydenov, Boris; Börner, Pia; Melentjevic, Kristina; Müller, Christoph; McGuinness, Liam Paul; Pezzagna, Sebastien; Meijer, Jan; Kaiser, Ute; Jelezko, Fedor

    2016-01-01

    A solid understanding of the implantation process of N and Si ions into diamond is needed for the controlled creation of shallow color centers for quantum computing, simulation, and sensing applications. Here, molecular dynamics simulations of the shallow implantation of N and Si ions into diamond is simulated at 100-5000 eV kinetic energies and different angles of incidence. We find that ion channeling is an important effect with an onset energy depending on the crystal orientation. Consequently, the molecular dynamics simulations produce improved predictions as compared to standard Monte Carlo simulations. When implanting in a channeling direction, the spatial distribution of the channeled ions becomes markedly narrow, allowing a higher degree of control over the location of the nitrogen vacancy (NV-) centers. A contamination layer on the ion entry surface reduces the fraction of channeled ions. A comparison to an experimentally determined depth profile based on a NMR signal from protons yields a quantitative agreement, validating the simulation approach.

  2. Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

    NASA Astrophysics Data System (ADS)

    Li, Fan; Sharma, Yogesh; Shah, Vishal; Jennings, Mike; Pérez-Tomás, Amador; Myronov, Maksym; Fisher, Craig; Leadley, David; Mawby, Phil

    2015-10-01

    A degenerated wide bandgap semiconductor is a rare system. In general, implant levels lie deeper in the band-gap and carrier freeze-out usually takes place at room temperature. Nevertheless, we have observed that heavily doped n-type degenerated 3C-SiC films are achieved by nitrogen implantation level of ∼6 × 1020 cm-3 at 20 K. According to temperature dependent Hall measurements, nitrogen activation rates decrease with the doping level from almost 100% (1.5 × 1019 cm-3, donor level 15 meV) to ∼12% for 6 × 1020 cm-3. Free donors are found to saturate in 3C-SiC at ∼7 × 1019 cm-3. The implanted film electrical performances are characterized as a function of the dopant doses and post implantation annealing (PIA) conditions by fabricating Van der Pauw structures. A deposited SiO2 layer was used as the surface capping layer during the PIA process to study its effect on the resultant film properties. From the device design point of view, the lowest sheet resistivity (∼1.4 mΩ cm) has been observed for medium doped (4 × 1019 cm-3) sample with PIA 1375 °C 2 h without a SiO2 cap.

  3. High-Sensitivity Temperature Sensing Using an Implanted Single Nitrogen-Vacancy Center Array in Diamond

    NASA Astrophysics Data System (ADS)

    Wang, Guanzhong; Wang, Junfeng; Advanced Thinfilm Laboratory, University of Science; Technology of China Team

    2015-03-01

    We present a high-sensitivity temperature detection using an implanted single Nitrogen-Vacancy center array in diamond. The high-order Thermal Carr-Purcell-Meiboom-Gill (TCPMG) method was performed on the implanted single nitrogen vacancy (NV) center in diamond in a static magnetic field. We demonstrated that under small detunings for the two driving microwave frequencies, the oscillation frequency of the induced fluorescence of the NV center equals approximately to the average of the detunings of the two driving fields. On basis of the conclusion, the zero-field splitting D for the NV center and the corresponding temperature could be determined. The experiment showed that the coherence time for the high-order TCPMG was effectively extended, particularly up to 108 μs for TCPMG-8, about 14 times of the value 7.7 μs for thermal Ramsey method. This coherence time corresponded to a thermal sensitivity of 10.1 mK/Hz1/2. We also detected the temperature distribution on the surface of a diamond chip by using the implanted NV center array with the TCPMG-3. Our approach implies the feasibility for using implanted NV centers in high-quality diamonds to detect temperatures with high-sensitivity and nanoscale resolution. This work was supported by the National Basic Research Program of China (2013CB921800, 2011CB921400) and the Natural Science Foundation of China (Grant Nos. 11374280, 50772110).

  4. Corrosion behaviors of Mo coating on stainless steel 316 substrates implanted by different nitrogen ion fluences

    NASA Astrophysics Data System (ADS)

    Mojtahedzadeh Larijani, Madjid; Bafandeh, Nastaran

    2014-03-01

    The molybdenum nitride coating was produced by nitrogen ion implantation of the molybdenum layer deposited on the stainless steel 316 (SS) substrates. At first, molybdenum layers were deposited on the substrates by ion beam sputtering method, then nitrogen ions with an energy of 30 keV and a fluence between 1×1017 and 12×1017 N+ cm-2 were implanted in Mo/SS system. Crystal structure and topography of the surface are investigated by grazing incidence X-ray diffraction (GIXRD) and atomic force microscopy (AFM) image respectively. XRD patterns showed the formation of molybdenum nitride phases in all implanted samples. Corrosion tests showed that the corrosion resistance of the samples strongly depends on the nitrogen applied fluences. A considerable improvement of corrosion performance by increasing ions fluences was observed. The lowest corrosion current density with amount of 0.1 μA/cm2 was obtained at 12×1017 ions/cm2 fluence in our case.

  5. Strain profile of (001) silicon implanted with nitrogen by plasma immersion

    SciTech Connect

    Diaz, B.; Abramof, E.; Castro, R. M.; Ueda, M.; Reuther, H.

    2007-05-15

    In this work, we investigate the strain and defect state of silicon implanted with nitrogen by plasma immersion ion implantation, with doses between 4.5x10{sup 16} and 8.7x10{sup 16} cm{sup -2}. For this purpose, we have used Auger electron spectroscopy, x-ray reflectivity, and high-resolution x-ray diffraction. Auger spectra showed that nitrogen concentration profiles broaden and shift deeper into the substrate as the dose increases. High oxygen concentration in the first 20 nm suggested the presence of an amorphous oxide layer at the sample surface, which was confirmed by x-ray reflectivity measurements. Reciprocal space maps revealed a tensile strain perpendicular to the surface, while no in-plane strain was detected. Since no significant diffuse scattering was found, randomly distributed point defects must be predominant in the strained region compared to large displacement field defects such as clusters and dislocations. {omega}/2{theta} scans around (004) Bragg reflection were fitted using dynamical theory of x-ray diffraction. The strain profiles obtained from the best fits correlated well with nitrogen concentration depth profiles, signaling interstitial nitrogen as the main source of strain.

  6. Luminescence studies on green emitting InGaN/GaN MQWs implanted with nitrogen

    PubMed Central

    Sousa, Marco A.; Esteves, Teresa C.; Sedrine, Nabiha Ben; Rodrigues, Joana; Lourenço, Márcio B.; Redondo-Cubero, Andrés; Alves, Eduardo; O'Donnell, Kevin P.; Bockowski, Michal; Wetzel, Christian; Correia, Maria R.; Lorenz, Katharina; Monteiro, Teresa

    2015-01-01

    We studied the optical properties of metalorganic chemical vapour deposited (MOCVD) InGaN/GaN multiple quantum wells (MQW) subjected to nitrogen (N) implantation and post-growth annealing treatments. The optical characterization was carried out by means of temperature and excitation density-dependent steady state photoluminescence (PL) spectroscopy, supplemented by room temperature PL excitation (PLE) and PL lifetime (PLL) measurements. The as-grown and as-implanted samples were found to exhibit a single green emission band attributed to localized excitons in the QW, although the N implantation leads to a strong reduction of the PL intensity. The green band was found to be surprisingly stable on annealing up to 1400°C. A broad blue band dominates the low temperature PL after thermal annealing in both samples. This band is more intense for the implanted sample, suggesting that defects generated by N implantation, likely related to the diffusion/segregation of indium (In), have been optically activated by the thermal treatment. PMID:25853988

  7. Improvement of Vitamin K2 Production by Escherichia sp. with Nitrogen Ion Beam Implantation Induction

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Wang, Li; Zheng, Zhiming; Wang, Peng; Zhao, Genhai; Liu, Hui; Gong, Guohong; Wu, Hefang; Liu, Hongxia; Tan, Mu; Li, Zhemin

    2015-02-01

    Low-energy ion implantation as a novel mutagen has been increasingly applied in the microbial mutagenesis for its higher mutation frequency and wider mutation spectra. In this work, N+ ion beam implantation was used to enhance Escherichia sp. in vitamin K2 yield. Optimization of process parameters under submerged fermentation was carried out to improve the vitamin K2 yield of mutant FM5-632. The results indicate that an excellent mutant FM5-632 with a yield of 123.2±1.6 μg/L, that is four times that of the original strain, was achieved by eight successive implantations under the conditions of 15 keV and 60×2.6×1013 ions/cm2. A further optimization increased the yield of the mutant by 39.7%, i.e. 172.1±1.2 μg/L which occurred in the mutant cultivated in the optimal fermentation culture medium composed of (per liter): 15.31 g glycerol, 10 g peptone, 2.89 g yeast extract, 5 g K2HPO4, 1 g NaCl, 0.5 g MgSO4·7H2O and 0.04 g cedar wood oil, incubated at 33 °C, pH 7.0 and 180 rpm for 120 h.

  8. Effects of nitrogen ion implantation time on tungsten films deposited by DC magnetron sputtering on AISI 410 martensitic stainless steel

    NASA Astrophysics Data System (ADS)

    Malau, Viktor; Ilman, Mochammad Noer; Iswanto, Priyo Tri; Jatisukamto, Gaguk

    2016-03-01

    Nitrogen ion implantation time on tungsten thin film deposited on surface of AISI 410 steel has been performed. Tungsten thin film produced by dc magnetron sputtering method was deposited on AISI 410 martensitic stainless steel substrates, and then the nitrogen ions were implanted on tungsten thin film. The objective of this research is to investigate the effects of implantation deposition time on surface roughness, microhardness, specific wear and corrosion rate of nitrogen implanted on tungsten film. Magnetron sputtering process was performed by using plasma gas of argon (Ar) to bombardier tungsten target (W) in a vacuum chamber with a pressure of 7.6 x 10-2 torr, a voltage of 300 V, a sputter current of 80 mA for sputtered time of 10 minutes. Nitrogen implantation on tungsten film was done with an initial pressure of 3x10-6 mbar, a fluence of 2 x 1017 ions/cm2, an energy of 100 keV and implantation deposition times of 0, 20, 30 and 40 minutes. The surface roughness, microhardness, specific wear and corrosion rate of the films were evaluated by surfcorder test, Vickers microhardness test, wear test and potentiostat (galvanostat) test respectively. The results show that the nitrogen ions implanted deposition time on tungsten film can modify the surface roughness, microhardness, specific wear and corrosion rate. The minimum surface roughness, specific wear and corrosion rate can be obtained for implantation time of 20 minutes and the maximum microhardness of the film is 329 VHN (Vickers Hardness Number) for implantation time of 30 minutes. The specific wear and corrosion rate of the film depend directly on the surface roughness.

  9. Plasma immersion ion implantation of nitrogen into H13 steel under moderate temperatures

    NASA Astrophysics Data System (ADS)

    Ueda, M.; Leandro, C.; Reuther, H.; Lepienski, C. M.

    2005-10-01

    Ion implantation of nitrogen into samples of tempered and quenched H13 steel was carried out by plasma immersion technique. A glow discharge plasma of nitrogen species was the ion source and the negative high voltage pulser provided 10-12 kV, 60 μs duration and 1.0-2.0 kHz frequency, flat voltage pulses. The temperatures of the samples remained between 300 and 450 °C, sustained solely by the ion bombardment. In some of the discharges, we used a N2 + H2 gas mixture with 1:1 ratio. PIII treatments as long as 3, 6, 9 and up to 12 h were carried out to achieve as thickest treated layer as possible, and we were able to reach over 20 μm treated layers, as a result of ion implantation and thermal (and possibly radiation enhanced) diffusion. The nitrogen depth profiles were obtained by GDOS (Glow Discharge Optical Spectroscopy) and the exact composition profiles by AES (Auger Electron Spectroscopy). The hardness of the treated surface was increased by more than 250%, reaching 18.8 GPa. No white layer was seen in this case. A hardness profile was obtained which corroborated a deep hardened layer, confirming the high efficacy of the moderate temperature PIII treatment of steels.

  10. Comparative Study on Effects of Low Energy N+ Implantation and γ-ray Radiation on Heredity and Development of Arabidopsis Thaliana

    NASA Astrophysics Data System (ADS)

    Zhang, Genfa; Li, Ke; Shi, Xiaoming; Nie, Yanli; Zhang, Jun; Zhou, Hongyu; Lu, Ting

    2005-06-01

    In order to compare the contemporary and genetic variation effect on Arabidopsis thaliana treated with N+ implantation and γ-ray radiation, the authors did some statistical comparison on the germinating rate and the development period, and analyzed the content of soluble proteins, the activity of some enzymes, isoenzymes profile, and along with the variation in genome DNA of two generations by RAPD. With N+ implantation there was an analogical "saddle model" relationship between doses and the plant development, soluble proteins, the activity of some enzymes and isoenzymes profile. A certain connection might exist between the similar dose-effect relations among enzymes activity, isoenzymes profile and content of soluble proteins. Maybe, there also exists a certain connection between the mutants of development period and that of DNA variations, between the hereditability of the effect of N+ implantation on the isoenzymes, the activities of enzymes and the hereditability of DNA variations. So it is presumed that the implanted ions, maybe, have participated in metabolism process of organism including that of genome DNA, to consequently affect vital process, such as the changes of gene structure, gene expression manner and gene repair mechanism, and finally result in mutation on phenotype and molecular level. Furthermore, the results definitely showed that mutagenic mechanism induced by N+ implantation is very complicated and is much different from that induced by traditional γ-ray radiation.

  11. Direct observation of enhanced emission sites in nitrogen implanted hybrid structured ultrananocrystalline diamond films

    SciTech Connect

    Panda, Kalpataru; Sundaravel, B.; Panigrahi, B. K.; Chen, Huang-Chin; Lin, I.-Nan

    2013-02-07

    A hybrid-structured ultrananocrystalline diamond (h-UNCD) film, synthesized on Si-substrates by a two-step microwave plasma enhanced chemical vapour deposition (MPECVD) process, contains duplex structure with large diamond aggregates evenly dispersed in a matrix of ultra-small grains ({approx}5 nm). The two-step plasma synthesized h-UNCD films exhibit superior electron field emission (EFE) properties than the one-step MPECVD deposited UNCD films. Nitrogen-ion implantation/post-annealing processes further improve the EFE properties of these films. Current imaging tunnelling spectroscopy in scanning tunnelling spectroscopy mode directly shows increased density of emission sites in N implanted/post-annealed h-UNCD films than as-prepared one. X-ray photoelectron spectroscopy measurements show increased sp{sup 2} phase content and C-N bonding fraction in N ion implanted/post-annealed films. Transmission electron microscopic analysis reveals that the N implantation/post-annealing processes induce the formation of defects in the diamond grains, which decreases the band gap and increases the density of states within the band gap of diamond. Moreover, the formation of nanographitic phase surrounding the small diamond grains enhanced the conductivity at the diamond grain boundaries. Both of the phenomena enhance the EFE properties.

  12. High-sensitivity temperature sensing using an implanted single nitrogen-vacancy center array in diamond

    NASA Astrophysics Data System (ADS)

    Wang, Junfeng; Feng, Fupan; Zhang, Jian; Chen, Jihong; Zheng, Zhongcheng; Guo, Liping; Zhang, Wenlong; Song, Xuerui; Guo, Guoping; Fan, Lele; Zou, Chongwen; Lou, Liren; Zhu, Wei; Wang, Guanzhong

    2015-04-01

    We presented a high-sensitivity temperature detection using an implanted single nitrogen-vacancy (NV) center array in diamond. The high-order thermal Carr-Purcell-Meiboom-Gill (TCPMG) method was performed on the implanted single NV center in diamond in a static magnetic field. We demonstrated that under small detunings for the two driving microwave frequencies, the oscillation frequency of the induced fluorescence of the NV center equals approximately the average of the detunings of the two driving fields. On the basis of the conclusion, the zero-field splitting D for the NV center and the corresponding temperature could be determined. The experiment showed that the coherence time for the high-order TCPMG was effectively extended, particularly up to 108 μ s for TCPMG-8, about 14 times the value 7.7 μ s for thermal Ramsey method. This coherence time corresponded to a thermal sensitivity of 10.1 mK/Hz1 /2. We also detected the temperature distribution on the surface of a diamond chip in three different circumstances by using the implanted NV center array with the TCPMG-3 method. The experiment implies the feasibility of using implanted NV centers in high-quality diamonds to detect temperatures in biology, chemistry, materials science, and microelectronic systems with high sensitivity and nanoscale resolution.

  13. Microstructural investigation of alumina implanted with 30 keV nitrogen ions

    NASA Astrophysics Data System (ADS)

    Shikha, Deep; Jha, Usha; Sinha, S. K.; Barhai, P. K.; Sarkhel, G.; Nair, K. G. M.; Dash, S.; Tyagi, A. K.; Kothari, D. C.

    2007-11-01

    Among ceramics, alumina is being widely used as biomaterials now these days. It is being used as hip joints, tooth roots etc. Ion implantation has been employed to modify its surface without changing it bulk properties. 30 keV nitrogen with varying ion dose ranging from 5 × 10 15 ions/cm 2 to 5 × 10 17 ions/cm 2 is implanted in alumina. Surface morphology has been studied with optical microscope and atomic force microscope (AFM). Improvement in brittleness has been observed with the increase in ion dose. Compound formation and changes in grain size have been studied using X-Ray diffraction (XRD). AlN compound formation is also observed by Fourier transform infrared spectroscopy (FTIR). The change in the grain size is related with the nanohardness and Hall-Petch relationship is verified.

  14. Characterization of the donor-acceptor-pair transition in Nitrogen-implanted zinc oxide

    SciTech Connect

    Stichtenoth, D.; Duerr, J.; Ronning, C.; Wischmeier, L.; Voss, T.

    2008-04-15

    Zinc oxide bulk crystals were doped with nitrogen by ion beam implantation. After postimplantation annealing, a luminescent transition appears at 3.230 eV. Power-dependent photoluminescence studies and time-resolved measurements at several spectral positions within this band can be described by a model for donor-acceptor-pair (DAP) transitions. By tracing the luminescence in a temperature-dependent study, a connection to phonon replicas could be excluded. Based on these results, this luminescence line could be clearly assigned to a DAP transition. In order to increase the doping efficiency, various approaches are considered and discussed. A slight increase could be obtained by high-temperature implantation without postimplantation annealing.

  15. A nuclear reaction analysis and optical microscopy study on controlled growth of large SiC nanocrystals on Si formed by low-energy ion implantation and electron beam annealing

    NASA Astrophysics Data System (ADS)

    Markwitz, A.; Lucas, F.; Rusterucci, J.; Kennedy, J.; Trompetter, W. J.; Rudolphi, M.; Ryan, M.; White, V.; Johnson, S.

    2006-08-01

    Ion implantation of 20 keV 12C+ ions into (1 0 0), p-type silicon with ion fluence of 8 × 1016 at. cm-2 followed by an electron beam annealing under high vacuum conditions has been performed to investigate the formation of crystalline nano-scale SiC features on the silicon surface. Depending on the implantation and annealing conditions, the SiC nanocrystal numbers and average spacing can be controlled by adjusting the implantation and annealing conditions. Typically 300-1000 SiC nanocrystals are produced per 1000 μm2 spaced 0.7-1.2 ± 0.1 μm. Nuclear reaction analysis measurements using the deuterium induced 12C(d, p)13C reaction show that carbon is present in the implanted and annealed samples and varies only to a small degree by the annealing time. However, by not using a liquid nitrogen trap surrounding the targets during implantation, the carbon contamination on the surface reduces the number of SiC nanocrystals and increases their average distance. Specific results are discussed.

  16. Enhancing Electrocatalytic Oxygen Reduction on Nitrogen-Doped Graphene by Active Sites Implantation

    NASA Astrophysics Data System (ADS)

    Feng, Leiyu; Yang, Lanqin; Huang, Zujing; Luo, Jingyang; Li, Mu; Wang, Dongbo; Chen, Yinguang

    2013-11-01

    The shortage of nitrogen active sites and relatively low nitrogen content result in unsatisfying eletrocatalytic activity and durability of nitrogen-doped graphene (NG) for oxygen reduction reaction (ORR). Here we report a novel approach to substantially enhance electrocatalytic oxygen reduction on NG electrode by the implantation of nitrogen active sites with mesoporous graphitic carbon nitride (mpg-C3N4). Electrochemical characterization revealed that in neutral electrolyte the resulting NG (I-NG) exhibited super electrocatalytic activity (completely 100% of four-electron ORR pathway) and durability (nearly no activity change after 100000 potential cyclings). When I-NG was used as cathode catalyst in microbial fuel cells (MFCs), power density and its drop percentage were also much better than the NG and Pt/C ones, demonstrating that the current I-NG was a perfect alternative to Pt/C and offered a new potential for constructing high-performance and less expensive cathode which is crucial for large-scale application of MFC technology.

  17. Enhancing Electrocatalytic Oxygen Reduction on Nitrogen-Doped Graphene by Active Sites Implantation

    PubMed Central

    Feng, Leiyu; Yang, Lanqin; Huang, Zujing; Luo, Jingyang; Li, Mu; Wang, Dongbo; Chen, Yinguang

    2013-01-01

    The shortage of nitrogen active sites and relatively low nitrogen content result in unsatisfying eletrocatalytic activity and durability of nitrogen-doped graphene (NG) for oxygen reduction reaction (ORR). Here we report a novel approach to substantially enhance electrocatalytic oxygen reduction on NG electrode by the implantation of nitrogen active sites with mesoporous graphitic carbon nitride (mpg-C3N4). Electrochemical characterization revealed that in neutral electrolyte the resulting NG (I-NG) exhibited super electrocatalytic activity (completely 100% of four-electron ORR pathway) and durability (nearly no activity change after 100000 potential cyclings). When I-NG was used as cathode catalyst in microbial fuel cells (MFCs), power density and its drop percentage were also much better than the NG and Pt/C ones, demonstrating that the current I-NG was a perfect alternative to Pt/C and offered a new potential for constructing high-performance and less expensive cathode which is crucial for large-scale application of MFC technology. PMID:24264379

  18. Nitrogen removal from eutrophic water by floating-bed-grown water spinach (Ipomoea aquatica Forsk.) with ion implantation.

    PubMed

    Li, Miao; Wu, Yue-Jin; Yu, Zeng-Liang; Sheng, Guo-Ping; Yu, Han-Qing

    2007-07-01

    The aim of this study was to investigate the use of water spinach (Ipomoea aquatica Forsk.) with N(+) ion-beam implantation for removal of nutrient species from eutrophic water. The mutated water spinach was grown on floating beds, and growth chambers were used to examine the growth of three cultivars of water spinach with ion implantation for 14 days in simulated eutrophic water at both high and low nitrogen levels. The specific weight growth rates of three cultivars of water spinach with ion implantation were significantly higher than the control, and their NO(3)-N and NH(4)-N removal efficiencies were also greater than those of the control. Furthermore, compared with the control, the nitrogen contents in the plant biomass with ion implantation were higher as well. PMID:17524443

  19. Differential Expression of Retrotransposon WIS 2-1A Response to Vacuum, Low-Energy N+ Implantation and 60Coγ-ray Irradiation in Wheat

    NASA Astrophysics Data System (ADS)

    Zhao, Huiru; Gu, Yunhong; Ya, Huiyuan; Jiao, Zhen; Qin, Guangyong

    2009-02-01

    Mutagenesis and retrotransposons have a close relationship, but little attention has been paid yet to the activity of retrotransposons produced by physical mutagens. The variation of retrotransposon WIS 2-1A activity in wheat (Triticum aestivum L.) embryos at three different growth times (30 h, 45 h and 60 h) was investigated after they had been treated with N+ implantation in a vacuum of 5 × 10-2 Pa and irradiation by 60Coγ-ray respectively. For each of the three growth times the expression of WIS 2-1A showed almost entirely a same trend of downregulation, upregulation, then downregulation, and upregulation again with the increase in dose of N+ implantation, but the expression appeared irregular with the increase in irradiation of 60Coγ-ray. In conclusion, the acutely activating effect of WIS 2-1A stimulated by vacuum and high dose N+ implantation within a shorter incubation time may provide a convenient tool to advance the research on mutagenic breeding and function genes.

  20. Nitrogen Plasma Ion Implantation of Al and Ti alloys in the High Voltage Glow Discharge Mode

    NASA Astrophysics Data System (ADS)

    Oliveira, R. M.; Ueda, M.; Rossi, J. O.; Reuther, H.; Lepienski, C. M.; Beloto, A. F.

    2006-11-01

    Enhanced surface properties can be attained for aluminum and its alloys (mechanical and tribological) and Ti6Al4V (mainly tribological) by Plasma Immersion Ion Implantation (PIII) technique. The main problem here, more severe for Al case, is the rapid oxygen contamination even in low O partial pressure. High energy nitrogen ions during PIII are demanded for this situation, in order to enable the ions to pass through the formed oxide layer. We have developed a PIII system that can operate at energies in excess of 50keV, using a Stacked Blumlein (SB) pulser which can nominally provide up to 100 kV pulses. Initially, we are using this system in the High Voltage Glow Discharge (HVGD) mode, to implant nitrogen ions into Al5052 alloy with energies in the range of 30 to 50keV, with 1.5μs duration pulses at a repetition rate of 100Hz. AES, pin-on-disc, nanoindentation measurements are under way but x-ray diffraction results already indicated abundant formation of AlN in the surface for Al5052 treated with this HVGD mode. Our major aim in this PIII experiment is to achieve this difficult to produce stable and highly reliable AlN rich surface layer with high hardness, high corrosion resistance and very low wear rate.

  1. Highly tunable formation of nitrogen-vacancy centers via ion implantation

    SciTech Connect

    Sangtawesin, S.; Brundage, T. O.; Atkins, Z. J.; Petta, J. R.

    2014-08-11

    We demonstrate highly tunable formation of nitrogen-vacancy (NV) centers using 20 keV {sup 15}N{sup +} ion implantation through arrays of high-resolution apertures fabricated with electron beam lithography. By varying the aperture diameters from 80 to 240 nm, as well as the average ion fluences from 5×10{sup 10} to 2 × 10{sup 11} ions/cm{sup 2}, we can control the number of ions per aperture. We analyze the photoluminescence on multiple sites with different implantation parameters and obtain ion-to-NV conversion yields of 6%–7%, consistent across all ion fluences. The implanted NV centers have spin dephasing times T{sub 2}{sup *} ∼ 3 μs, comparable to naturally occurring NV centers in high purity diamond with natural abundance {sup 13}C. With this technique, we can deterministically control the population distribution of NV centers in each aperture, allowing for the study of single or coupled NV centers and their integration into photonic structures.

  2. The effect of nitrogen ion implantation on the corrosion resistance and microstructure of tantalum-coated stainless steel

    NASA Astrophysics Data System (ADS)

    Eshghi, S.; Hanteh Zadeh, M.; Yari, M.; Jafari-Khamse, E.

    2014-06-01

    In this work, the effects of nitrogen ion implantation on the corrosion resistance and microstructure of DC magnetron sputtered tantalum-coated stainless steel were investigated. The nitrogen fluence was varied between 3-10 × 1017 ions/cm2 while the beam energy was kept constant at 30 keV. The effects of ion implantation were characterized by X-ray diffraction pattern, atomic force microscopy, and potentiodynamic corrosion test in a 0.5 MH2SO4 solution. The atomic force microscopy micrographs were quantitatively and statistically analyzed by computing the multifractal spectrum of the atomic force microscopy images. The results showed that the fluence variation strongly affected the surface roughness and formation of TaN and Ta2N phases. Increasing the nitrogen fluence up to 10 × 1017 ions/cm2 increased surface roughness. The highest corrosion resistance was obtained at 7 × 1017 ions/cm2 nitrogen fluence.

  3. Investigation of structural and optical properties of Ag nanoclusters formed in Si(100) after multiple implantations of low energies Ag ions and post-thermal annealing at a temperature below the Ag-Si eutectic point

    NASA Astrophysics Data System (ADS)

    Dhoubhadel, Mangal S.; Rout, Bibhudutta; Lakshantha, Wickramaarachchige J.; Das, Sushanta K.; D'Souza, Francis; Glass, Gary A.; McDaniel, Floyd D.

    2014-07-01

    Multiple low energies (78 keV, 68 keV and 58 keV) of Ag ions with different fluences up to 1×1016 atoms/cm2 were sequentially implanted into Si(100) to create a distribution of different sizes and densities of buried metal nanoclusters (NC) at the near-surface layers. These structures have applications in fields involving plasmonics, optical emitters, photovoltaic, and nano-electronics. The dimension, location and concentration of these NCs influence the type of the applications. The implantation profiles were simulated by utilizing the widely used Stopping and Range of Ions in Matter (SRIM) code as well as a dynamic-TRIM code, which accounts for surface sputtering. The implanted samples were subsequently annealed either in a gas mixture of 4% H2 + 96% Ar or in vacuum at a temperature ˜500 °C up to 90 minutes. The annealing was carried out below the eutectic temperature (˜ 841 °C) of Ag-Si to preferentially synthesize Ag NCs in Si rather than silicide. In order to study the size, concentration and distribution of the Ag NCs in Si, the samples were characterized by Rutherford Backscattering Spectrometry (RBS), X-ray photoelectron spectroscopy (XPS) in combination with Ar-ion etching, and Transmission Electron Microscopy (TEM) techniques. The annealed samples showed a preferential distribution of the Ag NCs' sizes up to 10 nm either near the surface region (< 25nm) or at deeper layers (60-80 nm) closer to the interface of the implanted layer with the crystalline Si substrate. Ag NCs of larger diameters (up to 15 nm) were seen in the annealed sample near the peak concentration positions (˜35-55 nm) of the implanted Ag ions. We have investigated the optical absorption properties due to these nano-structures in Si. The multiple energy implanted samples annealed in a gas mixture of 4% H2 + 96% Ar show enhancements in the optical absorption in the visible range.

  4. Etching and structural changes in nitrogen plasma immersion ion implanted polystyrene films

    NASA Astrophysics Data System (ADS)

    Gan, B. K.; Bilek, M. M. M.; Kondyurin, A.; Mizuno, K.; McKenzie, D. R.

    2006-06-01

    Plasma immersion ion implantation (PIII), with nitrogen ions of energy 20 keV in the fluence range of 5 × 1014-2 × 1016 ions cm-2, is used to modify 100 nm thin films of polystyrene on silicon wafer substrates. Ellipsometry is used to study changes in thickness with etching and changes in optical constants. Two distinctly different etch rates are observed as the polymer structure is modified. FTIR spectroscopy data reveals the structural changes, including changes in aromatic and aliphatic groups and oxidation and carbonisation processes, occurring in the polystyrene film as a function of the ion fluence. The transformation to a dense amorphous carbon-like material was observed to progress through an intermediate structural form containing a high concentration of Cdbnd C and Cdbnd O bonds.

  5. Electronic transport and localization in nitrogen-doped graphene devices using hyperthermal ion implantation

    NASA Astrophysics Data System (ADS)

    Friedman, Adam L.; Cress, Cory D.; Schmucker, Scott W.; Robinson, Jeremy T.; van 't Erve, Olaf M. J.

    2016-04-01

    Hyperthermal ion implantation offers a controllable method of producing high-quality substitutionally doped graphene with nitrogen, an n -type dopant that has great potential for graphene electronics and spintronics applications where high carrier concentration, uniform doping, and minimal vacancy defect concentration is desired. Here we examine the transport properties of monolayer graphene sheets as a function of implantation beam energy and dose. We observe a transition from weak to strong localization that varies as a function of carrier concentration. For nominally equivalent doses, increased N ion energy results in an increasing magnetoresistance magnitude, reaching a value of approximately -5.5% at 5000 Oe, which we discuss in the context of dopant concentration and defect formation. We use a model for the temperature dependence of the conductivity that takes into account both temperature activation, due to the formation of a transport gap, and Mott variable-range hopping, due to the formation of defects, to further study the electronic properties of the doped films as a function of dose and N ion energy. We find that the temperature activation component dominates the behavior.

  6. Correlation between defect and magnetism of low energy Ar+9 implanted and un-implanted Zn0.95Mn0.05O thin films suitable for electronic application

    NASA Astrophysics Data System (ADS)

    Neogi, S. K.; Midya, N.; Pramanik, P.; Banerjee, A.; Bhattacharyya, A.; Taki, G. S.; Krishna, J. B. M.; Bandyopadhyay, S.

    2016-06-01

    The structural, morphological, optical and magnetic properties of Ar+9 implanted 5 at% Mn doped ZnO films have been investigated to detect the correlation between ferromagnetism (FM) and defect. Sol-gel derived films were implanted with fluences 0 (un-implanted), 5×1014 (low), 1015 (intermediate) and 1016 (high) ions/cm2. Rutherford back scattering (RBS), X-ray diffraction (XRD), atomic force microscope (AFM) and magnetic force microscope (MFM), UV-visible, photoluminescence and X-ray absorption spectroscopy (XAS) and superconducting quantum interference device vibrating sample magnetometer (SQUID VSM) were employed for investigation. XRD indicated single phase nature of the films. Absence of impurity phase has been confirmed from several other measurements also. Ion implantation induces a large concentration of point defects into the films as identified from optical study. All films exhibit intrinsic FM at room temperature (RT). The magnetization attains the maximum for the film implanted with fluence 1016 ions/cm2 with saturation magnetization (MS) value 0.69 emu/gm at RT. Magnetic properties of the films were interpreted using bound magnetic polaron (BMP). BMP generated from the intrinsic exchange interaction of Mn2+ ions and VZn related defects actually controls the FM. The practical utility of these films in transparent spin electronic device has also been exhibited.

  7. Enhancement of nitrogen and phosphorus removal from eutrophic water by economic plant annual ryegrass (Lolium multiflorum) with ion implantation.

    PubMed

    Li, Miao; Sheng, Guo-ping; Wu, Yue-jin; Yu, Zeng-liang; Bañuelos, Gary S; Yu, Han-qing

    2014-01-01

    Severe eutrophication of surface water has been a major problem of increasing environmental concern worldwide. In the present study, economic plant annual ryegrass (Lolium multiflorum) was grown in floating mats as an economic plant-based treatment system to evaluate its potential after ion implantation for removing nutrients in simulated eutrophic water. The specific weight growth rate of L. multiflorum with ion implantation was significantly greater than that of the control, and the peroxidase, nitrate reductase, and acid phosphatase activities of the irradiated L. multiflorum were found to be greater than those plants without ion implantation. Higher total nitrogen (TN) and total phosphorus (TP) removal efficiencies were obtained for the L. multiflorum irradiated with 25 keV 5.2 × 10(16) N(+) ions/cm(2) and 30 keV 4.16 × 10(16) N(+) ions/cm(2), respectively (p < 0.05). Furthermore, the nitrogen and phosphorus contents in the plant biomass with ion implantation were also greater than those in the control and were positively correlated with TN and TP supplied. L. multiflorum itself was directly responsible for 39-49 and 47-58 % of the overall N and P removal in the experiment, respectively. The research results suggested that ion implantation could become a promising approach for increasing phytoremediation efficiency of nutrients from eutrophic water by L. multiflorum. PMID:24809498

  8. Single track nanodosimetry of low energy electrons

    NASA Astrophysics Data System (ADS)

    Bantsar, A.; Grosswendt, B.; Pszona, S.; Kula, J.

    2009-02-01

    Auger-electron-emitting radionuclides (for instance, 125I) with a predominant energy spectrum below 3 keV are an active area of research towards the clinical application of radiopharmaceuticals. Hence, the necessity for an adequate description of the effects of radiation by low-energy electrons on nanometric biological targets seems to be unquestionable. Experimental nanodosimetry for low-energy electrons has been accomplished with a device named JET COUNTER. The present paper describes, for the first time, nanodosimetric experiments in nanometer-sized cavities of nitrogen using low energy electrons ranging from 100 eV to 2 keV.

  9. Corrosion Behaviour of Nitrogen-Implantation Ti-Ta-Nb Alloy in Physiological Solutions Simulating Real Conditions from Human Body

    NASA Astrophysics Data System (ADS)

    Drob, Silviu Iulian; Vasilescu, Cora; Drob, Paula; Vasilescu, Ecaterina; Gordin, Doina Margareta; Gloriant, Thierry

    2015-04-01

    We applied a new nitrogen-implantation technique (trademark Hardion+) using a source of nitrogen ions, electron cyclotron resonance that assures higher energy and deeper implantation than the conventional techniques. The N-implantation surface of the new Ti-25Ta-25Nb alloy was analyzed as follows: for the phase identification by x-ray diffraction (XRD) in a glancing geometry (1°); for the hardness by the nano-indentation method; for the corrosion behaviour in Ringer solutions of different pH values (simulating the real conditions from the human body) by cyclic and linear polarization, electrochemical impedance spectroscopy and the monitoring of the open circuit potentials and corresponding potential gradients. XRD pattern was indexed with face-centred cubic TiN compound partially substituted with TaN and NbN. The hardness increased about 2 times for the N-implantation alloy. The implantation layer had a protection effect, increasing the corrosion and passivation potentials and decreasing the tendency to passivation and passive current density, due to its compactness, reinforcement action. The corrosion current density and rate decreased by about 10 times and the polarization resistance increased by about 2 times, indicative of a more resistant nitride layer. The porosity was much reduced and the protection efficiency had values closed to 90%, namely the implantation treatment led to the formation of a dense, resistant layer. Impedance spectra showed that the capacitive behaviour of the N-implantation alloy was more insulating and protective. An electric equivalent circuit with two times constants was modelled.

  10. Nitriding of AISI 4140 steel by a low energy broad ion source

    SciTech Connect

    Ochoa, E. A.; Figueroa, C. A.; Alvarez, F.

    2006-11-15

    A comprehensive study of the thermochemical nitriding process of steel AISI 4140 by low energy ion implantation (Kaufmann cell) is reported. Different times of implantation were employed and the studied samples were characterized by x-ray diffraction, in situ photoemission electron spectroscopy, scanning electron microscopy, and hardness (nanoindentation) measurements. The linear relationship between nitrogen content and hardness was verified. The structure of the nitrided layer was characterized yielding that the compound layer is formed by coarse precipitates, around small grains, constituted principally by {epsilon}-Fe{sub 2-3}N and {gamma}-Fe{sub 4}N phases and the diffusion zone is formed by fine precipitates, around big grains of the original martensitic phase, constituted principally by {gamma}-Fe{sub 4}N phase. Finally, a diffusion model for multiphase systems was applied to determine effective diffusion coefficients of nitrogen in the different phases.

  11. Mutation-Screening of Pleurotus Ferulae with High Temperature Tolerance by Nitrogen Ion Implantation

    NASA Astrophysics Data System (ADS)

    Chen, Henglei; Wan, Honggui; Zhang, Jun; Zeng, Xianxian

    2008-08-01

    In order to obtain Pleurotus ferulae with high temperature tolerance, conidiophores of wild type strain ACK were implanted with nitrogen ions in energy of 5 ~15 keV and dose of 1.5 × 1015 ~ 1.5 × 1016 cm-2, and a mutant CGMCC1763 was isolated subsequently through thermotolerant screening method. It was found that during riper period the surface layer mycelium of the mutant in mushroom bag wasn't aging neither grew tegument even above 30° C. The mycelium endurable temperature of the mutant was increased by 5°C compared to that of the wild type strain. The fruiting bodies growth temperature of the mutant was 18 ~22°C in daytime and 8~14°C at night. The highest growth temperature of fruiting bodies of the mutant was increased about 7°C w.r.t. that of original strain. Through three generations investigations, it was found that the mutant CGMCC1763 was stable with high temperature tolerance.

  12. Nanoarchitectured Co-Cr-Mo orthopedic implant alloys: nitrogen-enhanced nanostructural evolution and its effect on phase stability.

    PubMed

    Yamanaka, Kenta; Mori, Manami; Chiba, Akihiko

    2013-04-01

    Our previous studies indicate that nitrogen addition suppresses the athermal γ (face-centered cubic, fcc)→ε (hexagonal close-packed, hcp) martensitic transformation of biomedical Co-Cr-Mo alloys and ultimately offers large elongation to failure while maintaining high strength. In the present study, structural evolution and dislocation slip as an elementary process in the martensitic transformation in Co-Cr-Mo alloys were investigated to reveal the origin of their enhanced γ phase stability due to nitrogen addition. Alloy specimens with and without nitrogen addition were prepared. The N-doped alloys had a single-phase γ matrix, whereas the N-free alloys had a γ/ε duplex microstructure. Irrespective of the nitrogen content, dislocations frequently dissociated into Shockley partial dislocations with stacking faults. This indicates that nitrogen has little effect on the stability of the γ phase, which is also predicted by thermodynamic calculations. We discovered short-range ordering (SRO) or nanoscale Cr2N precipitates in the γ matrix of the N-containing alloy specimens, and it was revealed that both SRO and nanoprecipitates function as obstacles to the glide of partial dislocations and consequently significantly affect the kinetics of the γ→ε martensitic transformation. Since the formation of ε martensite plays a crucial role in plastic deformation and wear behavior, the developed nanostructural modification associated with nitrogen addition must be a promising strategy for highly durable orthopedic implants. PMID:23253619

  13. Ability of a gridless ion source to functionalize polypropylene surfaces by low-energy (60-100 eV) nitrogen ion bombardment. Effects of ageing in air and in water

    NASA Astrophysics Data System (ADS)

    Köhler, Laurent; Scaglione, Salvatore; Flori, Daniele; Riga, Joseph; Caudano, Roland

    2001-12-01

    Polymer surface treatments are of great importance for various industrial applications that can range from food packaging or car bumper painting to biocompatible implants. For such applications, plasma or corona discharges are well known and used "on-line" in polymer plants to incorporate new chemical functions at polymer surfaces. The aim of this work is to investigate the ability of a simple ion source to functionalize polypropylene surfaces in comparison with these intensively used industrial methods. Estimation of the influence of the nitrogen ion dose (from 1×10 15 to 1×10 16 ions/ cm2) and the ion energy (from 60 to 100 eV) on incorporation is attempted in order to be able to use them in a controlled way. The ageing of these polymer surfaces in air and in water was studied by XPS for several months.

  14. Low energy supersymmetry phenomenology

    SciTech Connect

    Baer, H.; Chen, C.H.; Bartl, A.; Feng, J.; Fujii, K.; Gunion, J.; Kamon, T.; Lopez, J.L.; Kao, C.

    1995-04-01

    The authors summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, they evaluate the capabilities of various e{sup +}e{sup {minus}}, p{bar p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, they discuss capabilities of future facilities to disentangle the anticipated spectrum of super-particles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. The authors then comment upon the complementarity of proposed hadron and e{sup +}e{sup {minus}} machines for a comprehensive study of low energy supersymmetry.

  15. Low energy supersymmetry phenomenology

    SciTech Connect

    Baer, H.; Chen, C.H.; Bartl, A.

    1995-03-01

    The authors summarize the current status and future prospects for low energy (weak scale) supersymmetry. In particular, they evaluate the capabilities of various e{sup +}e{sup {minus}}, p{anti p} and pp colliders to discover evidence for supersymmetric particles. Furthermore, assuming supersymmetry is discovered, they discuss capabilities of future facilities to disentangle the anticipated spectrum of superparticles, and, via precision measurements, to test mass and coupling parameters for comparison with various theoretical expectations. They comment upon the complementarity of proposed hadron and e{sup +}e{sup {minus}} machines for a comprehensive study of low energy supersymmetry.

  16. A study of interface and adhesion of c-BN film on Si(1 0 0) modified by nitrogen plasma based ion implantation technique

    SciTech Connect

    Tian Jingze; Zhang Qing; Xia Lifang; Yoon, S.F.; Ahn, J.; Byon, E.S.; Zhou, Q.; Wang, S.G.; Li, J.Q.; Yang, D.J

    2004-06-08

    Cubic boron nitride (c-BN) films were deposited on Si substrate with poor adhesion using magnetically enhanced active reaction evaporation (ME-ARE). An attempt has been made to enhance the adhesion strength between c-BN film and substrate by nitrogen plasma based ion implantation (PBII) into c-BN film. Nitrogen ion doses range from 5x10{sup 16} to 1x10{sup 17} ions cm{sup -2} at an implant voltage of 50 kV. The nitrogen ion implanted c-BN films were analyzed using FTIR, scratch test, and XPS to investigate the change of structure, adhesion strength of c-BN film, and interfacial mixing between the initial turbostratic BN (t-BN) film layer and substrate caused by nitrogen ion implantation. FTIR spectra showed little change of c-BN phase content in the films under the above implantation conditions but XPS depth elemental profile of N{sup +}-implanted boron nitride films displayed a mixed layer consisting of elements from film and substrate formed at interface. A highly optimized dynamic Monte Carlo program TAMIX was used to simulate the PBII process in a good agreement with above measured depth elemental profile. The scratch test showed that the adhesion strength evaluated in terms of the critical load of N{sup +}-implanted c-BN film was 1.4 times higher than that of as deposited c-BM film.

  17. LOW ENERGY COUNTING CHAMBERS

    DOEpatents

    Hayes, P.M.

    1960-02-16

    A beta particle counter adapted to use an end window made of polyethylene terephthalate was designed. The extreme thinness of the film results in a correspondingly high transmission of incident low-energy beta particles by the window. As a consequence, the counting efficiency of the present counter is over 40% greater than counters using conventional mica end windows.

  18. Bias in bonding behavior among boron, carbon, and nitrogen atoms in ion implanted a-BN, a-BC, and diamond like carbon films

    SciTech Connect

    Genisel, Mustafa Fatih; Uddin, Md. Nizam; Say, Zafer; Bengu, Erman; Kulakci, Mustafa; Turan, Rasit; Gulseren, Oguz

    2011-10-01

    In this study, we implanted N{sup +} and N{sub 2}{sup +} ions into sputter deposited amorphous boron carbide (a-BC) and diamond like carbon (DLC) thin films in an effort to understand the chemical bonding involved and investigate possible phase separation routes in boron carbon nitride (BCN) films. In addition, we investigated the effect of implanted C{sup +} ions in sputter deposited amorphous boron nitride (a-BN) films. Implanted ion energies for all ion species were set at 40 KeV. Implanted films were then analyzed using x-ray photoelectron spectroscopy (XPS). The changes in the chemical composition and bonding chemistry due to ion-implantation were examined at different depths of the films using sequential ion-beam etching and high resolution XPS analysis cycles. A comparative analysis has been made with the results from sputter deposited BCN films suggesting that implanted nitrogen and carbon atoms behaved very similar to nitrogen and carbon atoms in sputter deposited BCN films. We found that implanted nitrogen atoms would prefer bonding to carbon atoms in the films only if there is no boron atom in the vicinity or after all available boron atoms have been saturated with nitrogen. Implanted carbon atoms also preferred to either bond with available boron atoms or, more likely bonded with other implanted carbon atoms. These results were also supported by ab-initio density functional theory calculations which indicated that carbon-carbon bonds were energetically preferable to carbon-boron and carbon-nitrogen bonds.

  19. Effect of Nitrogen Implantation with Low Dose on Thermomechanical Properties and Microstructure of Ge2Sb2Te5 Films

    NASA Astrophysics Data System (ADS)

    Park, Il-Mok; Jung, Jung-Kyu; Yang, Tae-Youl; Yeom, Min Soo; Kim, Yong Tae; Joo, Young-Chang

    2008-03-01

    Ge2Sb2Te5 (GST) films with a thickness of 300 nm, in which the nitrogen (N) implant dose was 0, 1013, or 1015 ions/cm2, were prepared by RF magnetron sputtering on Si and glass substrates. The thermomechanical properties of the GST films, viz., the biaxial modulus and coefficient of thermal expansion (CTE), were determined using the substrate curvature method for the two different substrates. The biaxial modulus of the GST films decreased with increasing N dose, whereas the CTE varied only slightly. The dependence of the microstructure on the N implantation dose was examined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscopy (FE-SEM). The lattice parameter of the crystalline structure increased with increasing N dose, which indicated the distortion of the lattice by the implanted N atoms. Because the crystallite size increased with increasing N dose, grain growth refinement caused by the formation of nitrides did not occur. Also, the presence of nitrides in the N-implanted GST film was not observed in the binding energy spectra of 1s for the N element.

  20. Low energy antiproton beams

    NASA Astrophysics Data System (ADS)

    Klapisch, R.

    1992-04-01

    It was the invention of stochastic cooling by S. Van Meer that has allowed antiproton beams to become a powerful tool for the physicist. As a byproduct of the high energy proton-antiproton collider, a versatile low-energy facility, LEAR has been operating at CERN since 1984. The facility and its characteristics will be described as well as examples of its use for studying fundamental properties of the antiproton and for topics in atomic, nuclear and particle Physics.

  1. Interaction between Low Energy Ions and the Complicated Organism

    NASA Astrophysics Data System (ADS)

    Yu, Zeng-liang

    1999-12-01

    Low energy ions exist widely in natural world, but people pay a little attention on the interaction between low energy ions and matter, it is even more out of the question of studying on the relation of low energy ions and the complicated organism. The discovery of bioeffect induced by ion implantation has, however, opened a new branch in the field of ion beam application in life sciences. This paper reports recent advances in research on the role of low energy ions in chemical synthesis of the biomolecules and application in genetic modification.

  2. Low-energy neutrinos

    NASA Astrophysics Data System (ADS)

    Ludhova, Livia

    2016-05-01

    There exist several kinds of sources emitting neutrinos in the MeV energy range. These low-energy neutrinos from different sources can be often detected by the same multipurpose detectors. The status-of-art of the field of solar neutrinos, geoneutrinos, and the search for sterile neutrino with artificial neutrino sources is provided here; other neutrino sources, as for example reactor or high-energy neutrinos, are described elsewhere. For each of these three fields, the present-day motivation and open questions, as well as the latest experimental results and future perspectives are discussed.

  3. Polycrystalline silicon thin-film transistor with nickel-titanium oxide by sol-gel spin-coating and nitrogen implantation

    NASA Astrophysics Data System (ADS)

    Wu, Shih-Chieh; Hou, Tuo-Hung; Chuang, Shiow-Huey; Chou, Hsin-Chih; Chao, Tien-Sheng; Lei, Tan-Fu

    2012-12-01

    This study demonstrates polycrystalline silicon thin-film transistors (poly-Si TFTs) integrated with a high-κ nickel-titanium oxide (NiTiO3) gate dielectric using sol-gel spin-coating and nitrogen channel implantation. This novel fabrication method of the high-κ NiTiO3 gate dielectric offers thin equivalent-oxide thickness and high gate capacitance density, favorable for increasing the current driving capability. Introducing nitrogen ions into the poly-Si using implantation effectively passivates the trap states not only in the poly-Si channel but also at the gate dielectric/poly-Si interface. The poly-Si NiTiO3 TFTs with nitrogen implantation exhibit significantly improved electrical characteristics, including lower threshold voltage, a steeper subthreshold swing, higher field-effect mobility, a larger on/off current ratio, and less threshold-voltage roll-off. Furthermore, the nitrogen implantation improves the reliability of poly-Si NiTiO3 TFTs against hot-carrier stress and positive bias temperature instability.

  4. Towards Low Energy Atrial Defibrillation

    PubMed Central

    Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, Omar

    2015-01-01

    transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation. PMID:26404298

  5. Towards Low Energy Atrial Defibrillation.

    PubMed

    Walsh, Philip; Kodoth, Vivek; McEneaney, David; Rodrigues, Paola; Velasquez, Jose; Waterman, Niall; Escalona, Omar

    2015-01-01

    transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation. PMID:26404298

  6. The variation of hydrophobicity of aluminum alloy by nitrogen and argon ion implantation

    NASA Astrophysics Data System (ADS)

    Do, Sang Cheol; Kim, Ki Wook; Jeong, Ji Hwan

    2015-04-01

    Nitrogen and argon ions were irradiated on the surface of aluminum alloy. Ion irradiation appeared to increase contact angle of the metallic specimens. In order to investigate the factors affecting the changes of contact angles, changes in the characteristics of the surfaces were examined using SEM, AFM, and X-ray diffraction. The contact angle increased due to surface composition changes and surface roughness changes.

  7. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, ammonia was produced by 15 companies at 26 plants in 16 states in the United States. Of the total ammonia production capacity, 55% was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas. US producers operated at 66% of their rated capacity. In descending order, Koch Nitrogen, Terra Industries, CF Industries, Agrium and PCS Nitrogen accounted for 81% of the US ammonia production capacity.

  8. Study of non-linear Hall effect in nitrogen-grown ZnO microstructure and the effect of H{sup +}-implantation

    SciTech Connect

    Kumar, Yogesh Bern, Francis; Barzola-Quiquia, Jose; Lorite, Israel; Esquinazi, Pablo

    2015-07-13

    We report magnetotransport studies on microstructured ZnO film grown by pulsed laser deposition in N{sub 2} atmosphere on a-plane Al{sub 2}O{sub 3} substrates and the effect of low energy H{sup +}-implantation. Non-linearity has been found in the magnetic field dependent Hall resistance, which decreases with temperature. We explain this effect with a two-band model assuming the conduction through two different parallel channels having different types of charge carriers. Reduced non-linearity after H{sup +}-implantation in the grown film is due to the shallow-donor effect of hydrogen giving rise to an increment in the electron density, reducing the effect of the other channel.

  9. Effects of nitrogen-related defects on visible light photocatalytic response in N{sup +} implanted TiO{sub 2}: A first-principles study

    SciTech Connect

    Senga, Junya; Tatsumi, Kazuyoshi Muto, Shunsuke; Yoshida, Tomoko

    2015-09-21

    It was found that the visible-light responsiveness of a nitrogen ion-implanted TiO{sub 2} photocatalyst was attributable to the predominant chemical states of nitrogen, depending on the local nitrogen concentration near the surface. In the present study, we examined the effects of conceivable nitrogen-related defects on the visible light responsiveness, based on electronic structures calculated from first principles. Possible chemical states were proposed by comparing previously reported experiments with the present theoretical N-K X-ray absorption spectra. The theoretically predicted visible light absorption spectra and carrier trap states due to the bandgap states associated with the defects well explained the relationship between the catalytic reactivity and the proposed chemical states.

  10. Effects of nitrogen-related defects on visible light photocatalytic response in N+ implanted TiO2: A first-principles study

    NASA Astrophysics Data System (ADS)

    Senga, Junya; Tatsumi, Kazuyoshi; Muto, Shunsuke; Yoshida, Tomoko

    2015-09-01

    It was found that the visible-light responsiveness of a nitrogen ion-implanted TiO2 photocatalyst was attributable to the predominant chemical states of nitrogen, depending on the local nitrogen concentration near the surface. In the present study, we examined the effects of conceivable nitrogen-related defects on the visible light responsiveness, based on electronic structures calculated from first principles. Possible chemical states were proposed by comparing previously reported experiments with the present theoretical N-K X-ray absorption spectra. The theoretically predicted visible light absorption spectra and carrier trap states due to the bandgap states associated with the defects well explained the relationship between the catalytic reactivity and the proposed chemical states.

  11. Abrasive wear of nitrogen-implanted boron-coated Ti-6Al-4V and temperature effect on microhardness and sliding friction coefficient

    NASA Astrophysics Data System (ADS)

    Baazi, Tandjaoui; Knystautas, Emile J.; Fiset, Michel

    1993-02-01

    Boron was electron-gun evaporated onto manually polished surfaces of Ti-6Al-4V and bombarded with 100 keV nitrogen ions for different doses. The highest increase in Knoop microhardness was observed for the highest dose considered in this work, i.e., 10 17ions cm -2, which was maintained for subsequent abrasive wear investigation by optical and scanning electron microscopies. Relative changes of Knoop microhardness and sliding friction coefficient as a function of implantation temperature (room temperature, 150, 300, 450 and 600°C) were measured. The optimal improvements obtained for the 450°C implantation correlate with the higher nitrogen retention as evidenced by XPS depth-concentration analysis.

  12. Correlation between distribution of nitrogen atoms implanted at high energy and high dose and nanohardness measurements into 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Pelletier, H.; Mille, P.; Muller, D.; Stoquert, J. P.; Cornet, A.; Grob, J. J.

    2001-05-01

    Ion implantation causes changes in surface composition or morphology of solids which yield to a modification of physical and particularly mechanical properties, such as hardness, Young's modulus and elastic recovery. The purpose of this study is to focus on the effects occurring during the annealing process of stainless steel 316L samples implanted with high energy (1 MeV) nitrogen ions at high dose (10 18 N cm -2). From nuclear reaction analysis (NRA) measurements, the unusual shape of N distribution is discussed in terms of diffusion and precipitation mechanisms and correlated with the physical and chemical modifications observed with glancing incidence X-ray diffraction (GIXRD). Finally, from nanoindentation measurements, the real hardness profile is extracted using the Bückle's model eliminating the substrate effect. For each specimen, we show that the hardness is the sum of two terms, the first being related to nitrogen concentration and the second to various strengthening mechanisms depending on temperature.

  13. Nitrogen-Doped Graphene and Twisted Bilayer Graphene via Hyperthermal Ion Implantation with Depth Control.

    PubMed

    Cress, Cory D; Schmucker, Scott W; Friedman, Adam L; Dev, Pratibha; Culbertson, James C; Lyding, Joseph W; Robinson, Jeremy T

    2016-03-22

    We investigate hyperthermal ion implantation (HyTII) as a means for substitutionally doping layered materials such as graphene. In particular, this systematic study characterizes the efficacy of substitutional N-doping of graphene using HyTII over an N(+) energy range of 25-100 eV. Scanning tunneling microscopy results establish the incorporation of N substituents into the graphene lattice during HyTII processing. We illustrate the differences in evolution of the characteristic Raman peaks following incremental doses of N(+). We use the ratios of the integrated D and D' peaks, I(D)/I(D') to assess the N(+) energy-dependent doping efficacy, which shows a strong correlation with previously reported molecular dynamics (MD) simulation results and a peak doping efficiency regime ranging between approximately 30 and 50 eV. We also demonstrate the inherent monolayer depth control of the HyTII process, thereby establishing a unique advantage over other less-specific methods for doping. We achieve this by implementing twisted bilayer graphene (TBG), with one layer of isotopically enriched (13)C and one layer of natural (12)C graphene, and modify only the top layer of the TBG sample. By assessing the effects of N-HyTII processing, we uncover dose-dependent shifts in the transfer characteristics consistent with electron doping and we find dose-dependent electronic localization that manifests in low-temperature magnetotransport measurements. PMID:26910346

  14. Thermally stable oxygen and nitrogen implant isolation of C-doped Al{sub 0.35}Ga{sub 0.65}As

    SciTech Connect

    Zolper, J.C.; Sherwin, M.E.; Baca, A.G.; Schneider, R.P. Jr.

    1993-12-31

    Oxygen and nitrogen ion implantation have been applied to C-doped Al{sub 0.35}Ga{sub 0.65}As layers to produce high resistivity regions ({rho}{sub s} {ge} l {times} 10{sup 10} {Omega}/{open_square} that are stable after annealing at 900C. A dose threshold for stable compensation for both O and N ions was found above 8 {times} 10{sup l3} cm{sup {minus}2} for samples doped at 2 {times} 10{sup l8} cm{sup {minus}3}. Although O implantation has been reported to form stable compensation in Si-doped and Be-doped AlGaAs, the ability of nitrogen implantation to produce thermally stable compensation has not been previously reported and may be due to a C-N complex. The existence of this C-N complex is supported by results for O- and N-implants into C-doped GaAs where N formed thermally stable compensation but O did not. Sheet resistance data versus anneal temperature and estimates of the depth of the defect levels are reported. This result will have application to hetcrojunction bipolar transistors and complementary heterostructure field effect transistor technologies that employ C-doped AlGaAs or GaAs layers along with high temperature post-isolation processing.

  15. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2004-01-01

    Ammonia is the principal source of fixed nitrogen. It was produced by 17 companies at 34 plants in the United States during 2003. Fifty-three percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock.

  16. Synthesis of Fe16N2 compound Free-Standing Foils with 20 MGOe Magnetic Energy Product by Nitrogen Ion-Implantation

    NASA Astrophysics Data System (ADS)

    Jiang, Yanfeng; Mehedi, Md Al; Fu, Engang; Wang, Yongqiang; Allard, Lawrence F.; Wang, Jian-Ping

    2016-05-01

    Rare-earth-free magnets are highly demanded by clean and renewable energy industries because of the supply constraints and environmental issues. A promising permanent magnet should possess high remanent magnetic flux density (Br), large coercivity (Hc) and hence large maximum magnetic energy product ((BH)max). Fe16N2 has been emerging as one of promising candidates because of the redundancy of Fe and N on the earth, its large magnetocrystalline anisotropy (Ku > 1.0 × 107 erg/cc), and large saturation magnetization (4πMs > 2.4 T). However, there is no report on the formation of Fe16N2 magnet with high Br and large Hc in bulk format before. In this paper, we successfully synthesize free-standing Fe16N2 foils with a coercivity of up to 1910 Oe and a magnetic energy product of up to 20 MGOe at room temperature. Nitrogen ion implantation is used as an alternative nitriding approach with the benefit of tunable implantation energy and fluence. An integrated synthesis technique is developed, including a direct foil-substrate bonding step, an ion implantation step and a two-step post-annealing process. With the tunable capability of the ion implantation fluence and energy, a microstructure with grain size 25–30 nm is constructed on the FeN foil sample with the implantation fluence of 5 × 1017/cm2.

  17. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Ammonia was produced by 15 companies at 25 plants in 16 states in the United States during 2006. Fifty-seven percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock. In 2006, U.S. producers operated at about 72 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies, Koch Nitrogen, Terra Industries, CF Industries, PCS Nitro-gen, and Agrium, in descending order, accounted for 79 percent U.S. ammonia production capacity. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  18. Improvements of anti-corrosion and mechanical properties of NiTi orthopedic materials by acetylene, nitrogen and oxygen plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    Poon, Ray W. Y.; Ho, Joan P. Y.; Liu, Xuanyong; Chung, C. Y.; Chu, Paul K.; Yeung, Kelvin W. K.; Lu, William W.; Cheung, Kenneth M. C.

    2005-08-01

    Nickel-titanium shape memory alloys (NiTi) are useful materials in orthopedics and orthodontics due to their unique super-elasticity and shape memory effects. However, the problem associated with the release of harmful Ni ions to human tissues and fluids has been raising safety concern. Hence, it is necessary to produce a surface barrier to impede the out-diffusion of Ni ions from the materials. We have conducted acetylene, nitrogen and oxygen plasma immersion ion implantation (PIII) into NiTi alloys in an attempt to improve the surface properties. All the implanted and annealed samples surfaces exhibit outstanding corrosion and Ni out-diffusion resistance. Besides, the implanted layers are mechanically stronger than the substrate underneath. XPS analyses disclose that the layer formed by C2H2 PIII is composed of mainly TiCx with increasing Ti to C concentration ratios towards the bulk. The nitrogen PIII layer is observed to be TiN, whereas the oxygen PIII layer is composed of oxides of Ti4+, Ti3+ and Ti2+.

  19. Low Energy Schools in Ireland

    ERIC Educational Resources Information Center

    Heffernan, Martin

    2004-01-01

    Out of a commitment to reducing carbon dioxide emissions, Ireland's Department of Education and Science has designed and constructed two low energy schools, in Tullamore, County Offaly, and Raheen, County Laois. With energy use in buildings responsible for approximately 55% of the CO[subscript 2] released into the atmosphere and a major…

  20. Nitrogen induced modifications of MANOS memory properties

    NASA Astrophysics Data System (ADS)

    Nikolaou, N.; Ioannou-Sougleridis, V.; Dimitrakis, P.; Normand, P.; Skarlatos, D.; Giannakopoulos, K.; Ladas, S.; Pecassou, B.; BenAssayag, G.; Kukli, K.; Niinistö, J.; Ritala, M.; Leskelä, M.

    2015-12-01

    In this work we examine the structural and electrical properties including the memory performance of Al2O3/Si3N4/SiO2 dielectric stacks implanted with low-energy nitrogen ions and subsequently thermal annealed at 850 or 1050 °C for 15 min. X-ray photoelectron spectroscopy reveals that the concentration and the chemical state of the nitrogen atoms within the Al2O3 layer depends on the post-implantation annealing (PIA) temperature. Memory testing, performed on platinum gate capacitors, shows that charge retention of the programmed states is significantly improved for the high-temperature PIA samples as compared to the non-implanted samples. While such an improvement is not detected for the low-temperature PIA samples, the latter exhibit enhanced hole charging and thus, increased erase efficiency. Overall, our results suggest that the transport properties which control the erase and the retention characteristics of the blocking Al2O3 layer can be tailored by nitrogen implantation and the PIA conditions and can be used for memory performance optimization.

  1. The Low Energy Neutrino Factory

    SciTech Connect

    Bross, Alan; Geer, Steve; Ellis, Malcolm; Fernandez Martinez, Enrique; Li, Tracey; Pascoli, Silvia; Mena, Olga

    2010-03-30

    We show that a low energy neutrino factory with a baseline of 1300 km and muon energy of 4.5 GeV has an excellent physics reach. The results of our optimisation studies demonstrate that such a setup can have remarkable sensitivity to theta{sub 13} and delta for sin{sup 2}(2theta{sub 13})>10{sup -4}, and to the mass hierarchy for sin{sup 2}(2theta{sub 13})>10{sup -3}. We also illustrate the power of the unique combination of golden and platinum channels accessible to the low energy neutrino factory. We have considered both a 20 kton totally active scintillating detector and a 100 kton liquid argon detector as possible detector technologies, finding that a liquid argon detector with very good background rejection can produce sensitivity to theta{sub 13} and delta with that of the International Design Study neutrino factory.

  2. Physics with low energy hadrons

    SciTech Connect

    Guttierez, G.; Littenberg, L.

    1997-10-01

    The prospects for low energy hadron physics at the front end of a muon collider (FMC) are discussed. The FMC, as conceived for the purposes of this workshop, is pretty close to a classical idea of a koan factory. There is an order of magnitude advantage of the FMC front end over the AGS for K{sup {minus}} and {anti p} production below 5 GeV/c.

  3. Synthesis of Fe16N2 compound Free-Standing Foils with 20 MGOe Magnetic Energy Product by Nitrogen Ion-Implantation.

    PubMed

    Jiang, Yanfeng; Mehedi, Md Al; Fu, Engang; Wang, Yongqiang; Allard, Lawrence F; Wang, Jian-Ping

    2016-01-01

    Rare-earth-free magnets are highly demanded by clean and renewable energy industries because of the supply constraints and environmental issues. A promising permanent magnet should possess high remanent magnetic flux density (Br), large coercivity (Hc) and hence large maximum magnetic energy product ((BH)max). Fe16N2 has been emerging as one of promising candidates because of the redundancy of Fe and N on the earth, its large magnetocrystalline anisotropy (Ku > 1.0 × 10(7) erg/cc), and large saturation magnetization (4πMs > 2.4 T). However, there is no report on the formation of Fe16N2 magnet with high Br and large Hc in bulk format before. In this paper, we successfully synthesize free-standing Fe16N2 foils with a coercivity of up to 1910 Oe and a magnetic energy product of up to 20 MGOe at room temperature. Nitrogen ion implantation is used as an alternative nitriding approach with the benefit of tunable implantation energy and fluence. An integrated synthesis technique is developed, including a direct foil-substrate bonding step, an ion implantation step and a two-step post-annealing process. With the tunable capability of the ion implantation fluence and energy, a microstructure with grain size 25-30 nm is constructed on the FeN foil sample with the implantation fluence of 5 × 10(17)/cm(2). PMID:27145983

  4. Synthesis of Fe16N2 compound Free-Standing Foils with 20 MGOe Magnetic Energy Product by Nitrogen Ion-Implantation

    PubMed Central

    Jiang, Yanfeng; Mehedi, Md Al; Fu, Engang; Wang, Yongqiang; Allard, Lawrence F.; Wang, Jian-Ping

    2016-01-01

    Rare-earth-free magnets are highly demanded by clean and renewable energy industries because of the supply constraints and environmental issues. A promising permanent magnet should possess high remanent magnetic flux density (Br), large coercivity (Hc) and hence large maximum magnetic energy product ((BH)max). Fe16N2 has been emerging as one of promising candidates because of the redundancy of Fe and N on the earth, its large magnetocrystalline anisotropy (Ku > 1.0 × 107 erg/cc), and large saturation magnetization (4πMs > 2.4 T). However, there is no report on the formation of Fe16N2 magnet with high Br and large Hc in bulk format before. In this paper, we successfully synthesize free-standing Fe16N2 foils with a coercivity of up to 1910 Oe and a magnetic energy product of up to 20 MGOe at room temperature. Nitrogen ion implantation is used as an alternative nitriding approach with the benefit of tunable implantation energy and fluence. An integrated synthesis technique is developed, including a direct foil-substrate bonding step, an ion implantation step and a two-step post-annealing process. With the tunable capability of the ion implantation fluence and energy, a microstructure with grain size 25–30 nm is constructed on the FeN foil sample with the implantation fluence of 5 × 1017/cm2. PMID:27145983

  5. Wear and corrosion performance of two different tempers (T6 and T73) of AA7075 aluminium alloy after nitrogen implantation

    NASA Astrophysics Data System (ADS)

    Abreu, C. M.; Cristóbal, M. J.; Figueroa, R.; Pena, G.

    2015-02-01

    The present work reports the improvements in corrosion resistance and tribological properties achieved after Nitrogen ion implantation into aluminium alloy AA7075 subjected to two different tempers, T6 and T73. Nitrogen implantation at a nominal dose of 2 × 1017 ions/cm2 and at an accelerating voltage of 50 keV produced an increase of the surface hardness of the alloys up to a 130% in T6 samples and to 190% in T73 samples. The increase in hardness has a very positive effect on wear resistance as indicate the significant reduction of specific wear rate on both tempers (about -75% for T6 and -90% for T73 samples). Similarly, an improvement in corrosion properties of both tempers is confirmed by DC techniques, showing a decrease of the registered current density on potentiodynamic curves, and by the increase of impedance shown by AC techniques. This overall improvement in the alloy performance has been mainly attributed to the formation of a stoichiometric aluminium nitride layer (AlN), identified by XPS and GIXRD. The combination of EXCO immersion tests and electrochemical measurements allowed explaining the effect of AlN layer, which behave as a barrier delaying the onset of corrosion and slowing its progress. However, the implantation do not modified the corrosion morphology which seems to be determined mainly by the heat treating conditions. Thereby, in both tempers the localized attack starts at the intermetallic/matrix interface, but in T6 type specimens the progress of corrosion is clearly intergranular, while T73 specimens show the formation of clusters of small geometrical pits, probably related to the biggest MgZn2 strengthening precipitates.

  6. Production of [15O]Water at Low-Energy Proton Cyclotrons

    SciTech Connect

    Powell, James; O'Neil, James P.

    2005-12-12

    We report a simple system for producing [15O]H2O from nitrogen-15 in a nitrogen/hydrogen gas target with recycling of the target nitrogen, allowing production on low-energy proton-only accelerators with minimal consumption of isotopically enriched nitrogen-15. The radiolabeled water is separated from the target gas and radiolytically produced ammonia by temporary freezing in a small trap at -40 C.

  7. N-TiO2 nanoparticles embedded in silica prepared by Ti ion implantation and annealing in nitrogen

    SciTech Connect

    Xiang, Xia; Chen, Meng; Ju, Yongfeng; Zu, Xiaotao T.; Wang, Lumin M.; Zhang, Yanwen

    2010-05-01

    Room temperature Ti ion implantation and subsequent thermal annealing in N2 ambience have been used to fabricate the anatase and rutile structured N-doped TiO2 particles embedded in the surface region of fused silica. The Stopping and Range of Ions in Matter (SRIM) code simulation indicates a Gaussian distribution of implanted Ti, with a projected range of 74.4 nm and straggling of 16.5 nm. However, Rutherford backscattering spectrometry and transmission electron microscopy results show a much shallower distribution peaked at ~ 30 nm. Significant sputtering loss of silica substrates has occurred during implantation. Nanoparticles with size of 10-20 nm in diameter have formed after implantation. X-ray photoelectron spectroscopy indicates the coexistence of TiO2 and metallic Ti in the as-implanted samples. Metallic Ti is oxidized to anatase TiO2 after annealing at 600ºC, while rutile TiO2 forms by phase transformation after annealing at 900ºC. At the same time, N-Ti-O, Ti-O-N and/or Ti-N-O linkages have formed in the lattice of TiO2. A red shift of 0.34 eV in the absorption edge is obtained for N-doped anatase TiO2 after annealing at 600 ºC for 6 h. The absorbance increases in the ultraviolet and visible waveband.

  8. Low-Energy Proton Testing Methodology

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Marshall, Paul W.; Heidel, David F.; Schwank, James R.; Shaneyfelt, Marty R.; Xapsos, M.A.; Ladbury, Raymond L.; LaBel, Kenneth A.; Berg, Melanie; Kim, Hak S.; Phan, Anthony; Friendlich, M.R.; Rodbell, Kenneth P.; Hakey, Mark C.; Dodd, Paul E.; Reed, Robert A.; Weller, Robert A.; Mendenhall, Marcus H.; Sierawski, B.D.

    2009-01-01

    Use of low-energy protons and high-energy light ions is becoming necessary to investigate current-generation SEU thresholds. Systematic errors can dominate measurements made with low-energy protons. Range and energy straggling contribute to systematic error. Low-energy proton testing is not a step-and-repeat process. Low-energy protons and high-energy light ions can be used to measure SEU cross section of single sensitive features; important for simulation.

  9. Low energy p p physics

    SciTech Connect

    Amsler, C.; Crowe, K. . Inst. fuer Physik; Lawrence Berkeley Lab., CA )

    1989-02-01

    A detailed investigation of proton-antiproton interactions at low energy has become feasible with the commissioning of the LEAR facility in 1983. We shall shortly review the status of {bar p}p annihilation at rest and the physics motivations for second generation experiments with the Crystal Barrel detector. This type of detector would be adequate for the study of both Kp and {bar p}p interactions on an extracted beam of the KAON Factory. We shall conclude with a few remarks on the physics opportunities with {bar p}'s at the KAON Factory which, in our opinion, will not be covered by the present LEAR facility. 11 refs., 10 figs., 2 tabs.

  10. Analysis of low energy electrons

    NASA Technical Reports Server (NTRS)

    Sharp, R. D.

    1973-01-01

    Simultaneous observations of low energy electrons in the plasma sheet and in the auroral zone were analyzed. Data from the MIT plasma experiment on the OGO-3 satellite and from the Lockheed experiment on the OV1-18 satellite were processed and compared. The OV1-18 carried thirteen magnetic electron spectrometers designed to measure the intensity, angular, and energy distributions of the auroral electrons and protons in the energy range below 50 keV. Two computer programs were developed for reduction of the OV1-18 data. One program computed the various plasma properties at one second intervals as a function of Universal Time and pitch angle; the other program produced survey plots showing the outputs of the various detectors on the satellite as a function of time on a scale of approximately 100 seconds per cm. The OV1-18 data exhibit the high degree of variability associated with substorm controlled phenomena.

  11. Low-Energy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Wiedenbeck, M. E.; ACE/CRIS Collaboration

    2002-12-01

    Cosmic rays with energies below about 10 GeV/nucleon have been measured with high precision as a result of experiments on the HEAO, Ulysses, and ACE spacecrafts. The observations provide energy spectra, elemental abundances, and isotopic composition for elements up through Z=30. They include both stable and radioactive nuclides that are synthesized in stars or are produced by nuclear fragmentation during diffusion at high energies through interstellar medium. From these data one obtains a rather detailed picture of the origin of low-energy cosmic rays. For refractory species, the cosmic-ray source composition closely resembles that of the Sun, suggesting that cosmic rays are accelerated from a well-mixed sample of interstellar matter. A chemical fractionation process has depleted the abundances of volatile elements relative to refractories. Using various radioactive clock isotopes it has been shown that particle acceleration occurs at least 105 years after supernova nucleosynthesis and that the accelerated particles diffuse in the Galaxy for approximately 15 Myr after acceleration. Energy spectra and secondary-to-primary ratios are reasonably well accounted for by models in which particles gain the bulk of their energy in a single encounter with a strong shock. Among the large number of species that have been measured, 22Ne stands out as the only nuclide with an abundance that is clearly much different than solar. To test models proposed to account for this anomaly, the data are being analyzed for predicted smaller effects on abundances of other nuclides. In addition to providing a detailed understanding of the origin and acceleration of low-energy cosmic rays, these data are providing constraints on the chemical evolution of interstellar matter. This work was supported by NASA at Caltech (under grant NAG5-6912), JPL, NASA/GSFC, and Washington U.

  12. The low-energy ion range in DNA.

    PubMed

    Yu, L D; Kamwanna, T; Brown, I G

    2009-08-21

    In fundamental studies of low-energy ion irradiation effects on DNA, calculation of the low-energy ion range, an important basic physical parameter, is often necessary. However, up to now a unified model and approach for range calculation is still lacking, and reported data are quite divergent and thus unreliable. Here we describe an approach for calculation of the ion range, using a simplified mean-pseudoatom model of the DNA target. Based on ion stopping theory, for the case of low-energy (< or = a few keV) ion implantation into DNA, the stopping falls in the low reduced energy regime, which gives a cube-root energy dependence of the stopping (E(1/3)). Calculation formulas of the ion range in DNA are obtained and presented to unify the relevant calculations. The upper limits of the ion energy as a function of the atomic number of the bombarding ion species are proposed for the low-energy case to hold. Comparison of the results of this approach with the results of some widely used computer simulation codes and with results reported by other groups indicates that the approach described here provides convincing and dependable results. PMID:19652287

  13. Effect of nitrogen ion implantation on corrosion inhibition of nickel coated 316 stainless steel and correlation with nano-structure

    NASA Astrophysics Data System (ADS)

    Grayeli-Korpi, Ali-Reza; Savaloni, Hadi

    2012-10-01

    The influence of implantation of N+ with 20 keV energy and different fluences in the range of 1 × 1017 and 5 × 1018 ions/cm2 in the nickel coated type 316 stainless steel (SS) on the corrosion inhibition of SS in 3.5 wt% NaCl solution is investigated. The highest available N+ fluence showed highest corrosion inhibition. X-ray diffraction (XRD) analysis showed formation of nickel nitride phases that enhanced by increasing the N+ fluence. Surface morphology was studied by atomic force microscope (AFM) and scanning electron microscope (SEM) before and after corrosion test, respectively. AFM results showed that by increasing N+ fluence surface of the sample becomes smoother that may be the result of heat accumulation during implantation causing higher rate of diffusion in the sample.

  14. In situ x-ray diffraction investigations during low energy ion nitriding of austenitic stainless steel grade 1.4571

    NASA Astrophysics Data System (ADS)

    Manova, D.; Mändl, S.; Gerlach, J. W.; Hirsch, D.; Neumann, H.; Rauschenbach, B.

    2014-09-01

    Insertion of nitrogen into austenitic stainless steel leads to anomalously fast nitrogen diffusion and the formation of an expanded face-centred cubic phase which is known to contain a large amount of mechanical stress. In situ x-ray diffraction (XRD) measurements during low energy nitrogen ion implantation into steel 316Ti at 300-550 °C allow a direct view into diffusion and phase formation. While the layer growth is directly observable from the decreasing substrate reflection intensity, the time evolution of the intensities for the expanded phase reflection is much more complex: several mechanisms including at least formation and annealing of defects, twinning, reduction of the crystal symmetry, or grain rotation may be active inside the expanded phase, besides the thermally activated decay of the metastable expanded phase. This locally varying coherence length or scattering intensity from the expanded phase is furthermore a function of temperature and time, additionally complicating the deconvolution of XRD spectra for stress and concentration gradients. As no concise modelling of this coherence length is possible at present, a simple qualitative model assuming a dependence of the scattering intensity on the depth, influence by stress and plastic flow during the nitriding process is proposed for understanding the underlying processes.

  15. Intense low energy positron beams

    SciTech Connect

    Lynn, K.G.; Jacobsen, F.M.

    1993-12-31

    Intense positron beams are under development or being considered at several laboratories. Already today a few accelerator based high intensity, low brightness e{sup +} beams exist producing of the order of 10{sup 8} {minus} 10{sup 9} e{sup +}/sec. Several laboratories are aiming at high intensity, high brightness e{sup +} beams with intensities greater than 10{sup 9} e{sup +}/sec and current densities of the order of 10{sup 13} {minus} 10{sup 14} e{sup +} sec{sup {minus}} {sup 1}cm{sup {minus}2}. Intense e{sup +} beams can be realized in two ways (or in a combination thereof) either through a development of more efficient B{sup +} moderators or by increasing the available activity of B{sup +} particles. In this review we shall mainly concentrate on the latter approach. In atomic physics the main trust for these developments is to be able to measure differential and high energy cross-sections in e{sup +} collisions with atoms and molecules. Within solid state physics high intensity, high brightness e{sup +} beams are in demand in areas such as the re-emission e{sup +} microscope, two dimensional angular correlation of annihilation radiation, low energy e{sup +} diffraction and other fields. Intense e{sup +} beams are also important for the development of positronium beams, as well as exotic experiments such as Bose condensation and Ps liquid studies.

  16. Low energy effective string cosmology

    SciTech Connect

    Copeland, E.J.; Lahiri, A.; Wands, D. )

    1994-10-15

    We give the general analytic solutions derived from the low energy string effective action for four-dimensional Friedmann-Robertson-Walker models with a dilaton and antisymmetric tensor field, considering both long and short wavelength modes of the [ital H] field. The presence of a homogeneous [ital H] field significantly modifies the evolution of the scale factor and dilaton. In particular it places a lower bound on the allowed value of the dilaton. The scale factor also has a lower bound but our solutions remain singular as they all contain regions where the spacetime curvature diverges signalling a breakdown in the validity of the effective action. We extend our results to the simplest Bianchi type I metric in higher dimensions with only two scale factors. We again give the general analytic solutions for long and short wavelength modes for the [ital H] field restricted to the three-dimensional space, which produces an anisotropic expansion. In the case of [ital H] field radiation (wavelengths within the Hubble length) we obtain the usual four-dimensional radiation-dominated FRW model as the unique late time attractor.

  17. Low-Energy Sputtering Research

    NASA Technical Reports Server (NTRS)

    Ray, P. K.; Shutthanandan, V.

    1999-01-01

    An experimental study is described to measure low-energy (less than 600 eV) sputtering yields of molybdenum with xenon ions using Rutherford backscattering spectroscopy (RBS) and secondary neutral mass spectroscopy (SNMS). An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 (micro)A/sq cm. For RBS measurements, the sputtered material was collected on a thin aluminum strip which was mounted on a semi-circular collector plate. The target was bombarded with 200 and 500 eV xenon ions at normal incidence. The differential sputtering yields were measured using the RBS method with 1 MeV helium ions. The differential yields were fitted with a cosine fitting function and integrated with respect to the solid angle to provide the total sputtering yields. The sputtering yields obtained using the RBS method are in reasonable agreement with those measured by other researchers using different techniques. For the SNMS measurements, 150 to 600 eV xenon ions were used at 50deg angle of incidence. The SNMS spectra were converted to sputtering yields for perpendicular incidence by normalizing SNMS spectral data at 500 eV with the yield measured by Rutherford backscattering spectrometry. Sputtering yields as well as the shape of the yield-energy curve obtained in this manner are in reasonable agreement with those measured by other researchers using different techniques. Sputtering yields calculated by using two semi-spherical formulations agree reasonably well with measured data. The isotopic composition of secondary ions were measured by bombarding copper with xenon ions at energies ranging from 100 eV to 1.5 keV. The secondary ion flux was found to be enriched in heavy isotopes at low incident ion energies. The heavy isotope enrichment was observed to decrease with increasing impact energy. Beyond 700 eV, light isotopes were sputtered preferentially with the enrichment remaining nearly constant.

  18. Hydrogenation and dehydrogenation of nitrogen-doped graphene investigated by X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Späth, F.; Zhao, W.; Gleichweit, C.; Gotterbarm, K.; Bauer, U.; Höfert, O.; Steinrück, H.-P.; Papp, C.

    2015-04-01

    We studied the hydrogenation and dehydrogenation of nitrogen-doped graphene (NDG) by in situ high-resolution X-ray photoelectron spectroscopy (XPS) and temperature-programmed XPS (TPXPS). Nitrogen-doped graphene was prepared by low energy nitrogen implantation in pristine graphene on Ni(111). Hydrogenation of NDG was performed by exposure to atomic hydrogen. Upon hydrogenation the XP spectra in the C 1s region reveal one new peak, shifted to lower binding energies as compared to graphene, which is associated with newly formed CH groups. In the N 1s region two new peaks, shifted to higher binding energies are observed; these are associated with hydrogenated pyridinic and graphitic nitrogen. TPXPS spectra reveal a different thermal stability of the two hydrogenated nitrogen species, while the C-H groups of graphene show no significant changes compared to undoped hydrogenated graphene.

  19. Experimental study of low-energy charge transfer in nitrogen

    NASA Technical Reports Server (NTRS)

    Smith, A.

    1979-01-01

    Total charge transfer cross sections were obtained for the N2(+)-N2 system with relative translational ion energies between 9 and 441 eV. Data were obtained to examine the dependence of total cross section on ion energy. The effect of ion excitation on the cross sections was studied by varying the electron ionization energy in the mass spectrometer ion source over an electron energy range between 14.5 and 32.1 eV. The dependence of total cross section on the neutralization chamber gas pressure was examined by obtaining data at pressure values from 9.9 to 0.000199 torr. Cross section values obtained were compared with experimental and theoretical results of other investigations.

  20. Surface and bulk-loss reduction research by low-energy hydrogen doping

    NASA Technical Reports Server (NTRS)

    Fonash, S.

    1985-01-01

    Surface and bulk loss reduction by low energy hydrogen doping of silicon solar cells was examined. Hydrogen ions provided a suppression of space charge recombination currents. Implantation of hydrogen followed by the anneal cycle caused more redistribution of boron than the anneal which could complicate processing. It was demonstrated that passivation leads to space charge current reduction.

  1. Low-energy nuclear physics with high-segmentation silicon arrays

    SciTech Connect

    Betts, R.R. |

    1994-12-01

    A brief history is given of silicon detectors leading up to the development of ion-implanted strip detectors. Two examples of their use in low energy nuclear physics are discussed; the search for exotic alpha-chain states in {sup 24}Mg and studies of anomalous positron-electron pairs produced in collisions of very heavy ions.

  2. The Science of Low Energy Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Storms, Edmund

    2007-03-01

    The large literature describing the anomalous behavior attributed to cold fusion or low energy nuclear reactions has been critically described in a recently published book. Over 950 publications are evaluated allowing the phenomenon to be understood. A new class of nuclear reactions has been discovered that are able to generate practical energy without significant radiation or radioactivity. Edmund K Storms, The Science of Low Energy Nuclear Reactions, in press (2006). Also see: http://www.lenr-canr.org/StudentsGuide.htm .

  3. Solar nitrogen: evidence for a secular increase in the ratio of nitrogen-15 to nitrogen-14.

    PubMed

    Kerridge, J F

    1975-04-11

    Solar wind nitrogen, implanted in lunar soil samples, exhibits isotopic variations that are related to the time, although not to the duration, of implantation, with earlier samples characterized by lower ratios of nitrogen-15 to nitrogen-14. An increase in the solar nitrogen-15 content during the lifetime of the lunar regolith is probably caused by spallation of oxygen-16 in the surface regions of the sun. PMID:17813736

  4. Low energy aspects of circular accelerators

    SciTech Connect

    Holmes, S.D.

    1990-12-01

    Performance in circular accelerators can be limited by some of the same sorts of phenomena described by Miller and Wangler in their lectures on low energy behavior in linear accelerators. In general the strength of the perturbation required to degrade performance is reduced in circular accelerators due to the repetitive nature of the orbits. For example, we shall see that space-charge can severely limit performance in circular accelerators even when operating far from the space-charge dominated regime'' as defined in linear accelerators. We will be discussing two particular aspects of low energy operation in circular accelerators -- space-charge and transition. Low energy'' is defined within the context of these phenomena. We shall see that the phenomena are really only relevant in hadron accelerators.

  5. Low-energy electron-induced reactions in condensed matter

    NASA Astrophysics Data System (ADS)

    Arumainayagam, Christopher R.; Lee, Hsiao-Lu; Nelson, Rachel B.; Haines, David R.; Gunawardane, Richard P.

    2010-01-01

    The goal of this review is to discuss post-irradiation analysis of low-energy (≤50 eV) electron-induced processes in nanoscale thin films. Because electron-induced surface reactions in monolayer adsorbates have been extensively reviewed, we will instead focus on low-energy electron-induced reactions in multilayer adsorbates. The latter studies, involving nanoscale thin films, serve to elucidate the pivotal role that the low-energy electron-induced reactions play in high-energy radiation-induced chemical reactions in condensed matter. Although electron-stimulated desorption (ESD) experiments conducted during irradiation have yielded vital information relevant to primary or initial electron-induced processes, we wish to demonstrate in this review that analyzing the products following low-energy electron irradiation can provide new insights into radiation chemistry. This review presents studies of electron-induced reactions in nanoscale films of molecular species such as oxygen, nitrogen trifluoride, water, alkanes, alcohols, aldehydes, ketones, carboxylic acids, nitriles, halocarbons, alkane and phenyl thiols, thiophenes, ferrocene, amino acids, nucleotides, and DNA using post-irradiation techniques such as temperature-programmed desorption (TPD), reflection-absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), gel electrophoresis, and microarray fluorescence. Post-irradiation temperature-programmed desorption, in particular, has been shown to be useful in identifying labile radiolysis products as demonstrated by the first identification of methoxymethanol as a reaction product of methanol radiolysis. Results of post-irradiation studies have been used not only to identify radiolysis products, but also to determine the dynamics of electron-induced reactions. For example, studies of the radiolysis yield as a function of incident electron energy have shown that dissociative

  6. Low energy strong electroweak sector with decoupling

    SciTech Connect

    Casalbuoni, R.; Dominici, D. |; Deandrea, A.; Gatto, R.; De Curtis, S.; Grazzini, M. |

    1996-05-01

    We discuss possible symmetries of effective theories describing spinless and spin-1 bosons, mainly to concentrate on an intriguing phenomenological possibility: that of a hardly noticeable strong electroweak sector at relatively low energies. Specifically, a model with both vector and axial vector strong interacting bosons may possess a discrete symmetry imposing degeneracy of the two sets of bosons (degenerate BESS model). In such a case its effects at low energies become almost invisible and the model easily passes all low energy precision tests. The reason lies essentially in the fact that the model automatically satisfies decoupling, contrary to models with only vectors. For large mass of the degenerate spin-one bosons the model becomes identical at the classical level to the standard model taken in the limit of infinite Higgs boson mass. For these reasons we have thought it worthwhile to fully develop the model, together with its possible generalizations, and to study the expected phenomenology. For instance, just because of its invisibility at low energy, it is conceivable that degenerate BESS has low mass spin-one states and gives quite visible signals at existing or forthcoming accelerators. {copyright} {ital 1996 The American Physical Society.}

  7. Parity violation in low-energy

    SciTech Connect

    Martin Savage

    2001-12-01

    Parity violation in low-energy nuclear observables is included in the pionless effective field theory. The model-independent relation between the parity-violating asymmetry in polarized np -> d gamma and the non-nucleon part of the deuteron anapole moment is discussed. The asymmetry in np -> d gamma computed with KSW power-counting, and recently criticized by Desplanques, is discussed.

  8. Low energy [bar p] physics at FNAL

    SciTech Connect

    Hsueh, S.Y.

    1992-12-01

    The charmonium formation experiment is the only low energy [bar p] experiment at FNAL. This paper describes the performance of the Fermilab [bar p] Accumulator during fixed target run for the experiment and the planned upgrades. We also discuss the proposal for the direct CP violation search in [bar p] + p [yields] [bar [Lambda

  9. What is a low-energy house?

    SciTech Connect

    Litt, B.R.; Meier, A.K.

    1994-08-01

    Traditionally, a ``low-energy`` house has been one that used little energy for space heating. But space heating typically accounts for less than half of the energy used by new US homes, and for low heating energy homes, space heating is often the third largest end use, behind water heating and appliances, and sometimes behind cooling. Low space heat alone cannot identify a low-energy house. To better understand the determinants of a low-energy house, we collected data on housing characteristics, incremental costs, and energy measurements from energy-efficient houses around the world and in a range of climates. We compare the energy required to provide thermal comfort as well as water heating, and other appliances. We do not have a single definition of a low-energy house, but through comparisons of actual buildings, we show how different definitions and quantitative indicators fail. In comparing the energy use of whole houses, weather normalization can be important, but for cases in which heating or cooling energy is surpassed by other end uses, other normalization methods must be used.

  10. Low-energy Neutrino Astronomy in LENA

    NASA Astrophysics Data System (ADS)

    Wurm, M.; Bick, D.; Enqvist, T.; Hellgartner, D.; Kaiser, M.; Loo, K. K.; Lorenz, S.; Meloni, M.; Meyer, M.; Möllenberg, R.; Oberauer, L.; Soiron, M.; Smirnov, M.; Trzaska, W. H.; Wonsak, B.

    LENA (Low Energy Neutrino Astronomy) is a proposed next-generation neutrino detector based on 50 kilotons of liquid scintillator. The low detection threshold, good energy resolution and excellent background rejection inherent to the liquid-scintillator detectors make LENA a versatile observatory for low-energy neutrinos from astrophysical and terrestrial sources. In the framework of the European LAGUNA-LBNO design study, LENA is also considered as far detector for a very-long baseline neutrino beam from CERN to Pyhäsalmi (Finland). The present contribution gives an overview LENA's broad research program, highlighting the unique capabilities of liquid scintillator for the detection of low-energy neutrinos from astrophysical sources. In particular, it will focus on the precision measurement of the solar neutrino spectrum: The search for time modulations in the 7Be neutrino flux, the determination of the electron neutrino survival probability in the low-energy region of the 8B spectrum and the favorable detection conditions for neutrinos from the CNO fusion cycle.

  11. The Simbol-X Low Energy Detector

    SciTech Connect

    Lechner, Peter

    2009-05-11

    For the Low Energy Detector of Simbol-X a new type of active pixel sensor based on the integrated amplifier DEPFET has been developed. This concept combines large area, scalable pixel size, low noise, and ultra-fast readout. Flight representative prototypes have been processed with a performance matching the Simbol-X specifications and demonstrating the technology readiness.

  12. The low energy atmospheric antiproton albedo

    NASA Technical Reports Server (NTRS)

    Cole, J. B.; Ormes, J. F.

    1989-01-01

    The flux of albedo antiprotons in the 100-1000 MeV kinetic energy range produced by the cosmic ray primaries in the atmosphere is calculated. It is shown that this is not a significant background to measurements of the low energy anti-proton cosmic ray flux.

  13. Studies in Low-Energy Nuclear Science

    SciTech Connect

    Carl R. Brune; Steven M. Grimes

    2010-01-13

    This report presents a summary of research projects in the area of low energy nuclear reactions and structure, carried out between March 1, 2006 and October 31, 2009 which were supported by U.S. DOE grant number DE-FG52-06NA26187.

  14. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    Welch, J.J.

    1985-01-01

    The author built and tested a low energy cyclotron for radiocarbon dating similar to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity /sup 14/C measurements that are now done at accelerator facilities. The author found that no significant background is present when the cyclotron is tuned to accelerate /sup 14/C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect /sup 14/C directly at modern concentrations. The author shows how a conventional carbon negative ion source located outside the cyclotron magnet, would produce sufficient beam and provide for quick sample changing to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

  15. Low energy ion loss at Mars

    NASA Astrophysics Data System (ADS)

    Curry, S.; Liemohn, M.; Fang, X.; Ma, Y.

    2012-04-01

    Current data observations and modeling efforts have indicated that the low-energy pick-up ions on Mars significantly contribute to the overall escape rate. Due to the lack of a dipole magnetic field, the solar wind directly interacts with the dayside upper atmosphere causing particles to be stripped away. In this study, we use a 3-D Monte Carlo test particle simulation with virtual detectors to observe low energy ions (< 50 eV) in the Mars space environment. We will present velocity space distributions that can capture the asymmetric and non-gyrotropic features of particle motion. The effect of different solar conditions will also be discussed with respect to ion fluxes at various spatial locations as well as overall loss in order to robustly describe the physical processes controlling the distribution of planetary ions and atmospheric escape.

  16. Experimental Measurement of Low Energy Neutrino Interactions

    SciTech Connect

    Scholberg, Kate

    2011-11-23

    Neutrino interactions in the few to few tens of MeV range are of importance for several physics topics, including solar, supernova and reactor neutrinos, as well as future proposed oscillation and Standard Model test experiments. Although interaction cross-sections for some simple targets are well understood, very little experimental data exist for interactions with nuclei. This talk will discuss the motivation for measuring low energy neutrino interactions, the state of knowledge, and possible future strategies.

  17. PHYSICS WITH ULTRA-LOW ENERGY ANTIPROTONS

    SciTech Connect

    M. HOLZSCHEITER

    2001-02-01

    In this report the author describes the current status of the antiproton deceleration (AD) facility at CERN, and highlights the physics program with ultra-low energy antiproton at this installation. He also comments on future possibilities provided higher intensity antiproton beams become available at Fermilab, and review possibilities for initial experiments using direct degrading of high energy antiprotons in material has been developed and proven at CERN.

  18. First-principles study on the interaction of nitrogen atom with α–uranium: From surface adsorption to bulk diffusion

    SciTech Connect

    Su, Qiulei; Deng, Huiqiu E-mail: hqdeng@gmail.com; Xiao, Shifang; Li, Xiaofan; Hu, Wangyu; Ao, Bingyun; Chen, Piheng

    2014-04-28

    Experimental studies of nitriding on uranium surfaces show that the modified layers provide considerable protection against air corrosion. The bimodal distribution of nitrogen is affected by both its implantation and diffusion, and the diffusion of nitrogen during implantation is also governed by vacancy trapping. In the present paper, nitrogen adsorption, absorption, diffusion, and vacancy trapping on the surface of and in the bulk of α–uranium are studied with a first-principles density functional theory approach and the climbing image nudged elastic band method. The calculated results indicate that, regardless of the nitrogen coverage, a nitrogen atom prefers to reside at the hollow1 site and octahedral (Oct) site on and below the surface, respectively. The lowest energy barriers for on-surface and penetration diffusion occur at a coverage of 1/2 monolayer. A nitrogen atom prefers to occupy the Oct site in bulk α–uranium. High energy barriers are observed during the diffusion between neighboring Oct sites. A vacancy can capture its nearby interstitial nitrogen atom with a low energy barrier, providing a significant attractive nitrogen-vacancy interaction at the trapping center site. This study provides a reference for understanding the nitriding process on uranium surfaces.

  19. Targeting Low-Energy Ballistic Lunar Transfers

    NASA Technical Reports Server (NTRS)

    Parker, Jeffrey S.

    2010-01-01

    Numerous low-energy ballistic transfers exist between the Earth and Moon that require less fuel than conventional transfers, but require three or more months of transfer time. An entirely ballistic lunar transfer departs the Earth from a particular declination at some time in order to arrive at the Moon at a given time along a desirable approach. Maneuvers may be added to the trajectory in order to adjust the Earth departure to meet mission requirements. In this paper, we characterize the (Delta)V cost required to adjust a low-energy ballistic lunar transfer such that a spacecraft may depart the Earth at a desirable declination, e.g., 28.5(white bullet), on a designated date. This study identifies the optimal locations to place one or two maneuvers along a transfer to minimize the (Delta)V cost of the transfer. One practical application of this study is to characterize the launch period for a mission that aims to launch from a particular launch site, such as Cape Canaveral, Florida, and arrive at a particular orbit at the Moon on a given date using a three-month low-energy transfer.

  20. Low energy Skyrmion-Skyrmion scattering

    SciTech Connect

    Gisiger, T.; Paranjape, M.B. )

    1994-07-15

    We study the scattering of two Skyrmions at low energy and large separation. We use the method proposed by Manton for truncating the degrees of freedom of the system from infinite to a manageable finite number. This corresponds to identifying the manifold consisting of the union of the low energy critical points of the potential along with the gradient flow curves joining these together and by positing that the dynamics is restricted here. The kinetic energy provides an induced metric on this manifold while restricting the full potential energy to the manifold defines a potential. The low energy dynamics is now constrained to these finite number of degrees of freedom. For a large separation of the two Skyrmions the manifold is parametrized by the variables of the product ansatz. We find the interaction between two Skyrmions coming from the induced metric, which was independently found by Schroers. We find that the static potential is actually negligible in comparison to this interaction. Thus to lowest order, at large separation, the dynamics reduces to geodesic motion on the manifold. We consider the scattering to first order in the interaction using the perturbative method of Lagrange and find that the dynamics in the no spin or charge exchange sector reduces to the Kepler problem.

  1. Low energy Skyrmion-Skyrmion scattering

    NASA Astrophysics Data System (ADS)

    Gisiger, T.; Paranjape, M. B.

    1994-07-01

    We study the scattering of two Skyrmions at low energy and large separation. We use the method proposed by Manton for truncating the degrees of freedom of the system from infinite to a manageable finite number. This corresponds to identifying the manifold consisting of the union of the low energy critical points of the potential along with the gradient flow curves joining these together and by positing that the dynamics is restricted here. The kinetic energy provides an induced metric on this manifold while restricting the full potential energy to the manifold defines a potential. The low energy dynamics is now constrained to these finite number of degrees of freedom. For a large separation of the two Skyrmions the manifold is parametrized by the variables of the product ansatz. We find the interaction between two Skyrmions coming from the induced metric, which was independently found by Schroers. We find that the static potential is actually negligible in comparison to this interaction. Thus to lowest order, at large separation, the dynamics reduces to geodesic motion on the manifold. We consider the scattering to first order in the interaction using the perturbative method of Lagrange and find that the dynamics in the no spin or charge exchange sector reduces to the Kepler problem.

  2. Low-energy generation in nanostructured Si

    NASA Astrophysics Data System (ADS)

    Kuznicki, Zbigniew T.; Meyrueis, Patrick

    2008-04-01

    Solar photon energy can be better used when totally transformed on collectable free-carriers. The conversion of one energetic photon could result in more than one free-carrier pair if a low-energy mechanism is involved. Such PV conversion represents a multistage nonlinear process and requires especially dedicated low-energy centers. A cascade-like progression is induced by the primary/fundamental/interband absorption. As shown by us previously, the corresponding structure can be realized, for example, with nanostructured Si. The experimental devices convert 400 nm photons into collectable primary and secondary free-carriers. The excess carriers can be drawn out into the external electrical circuit even in a multiinterface architecture containing a carrier collection limit. The superficial effect seems to be totally independent of the presence or not of a buried amorphized layer. This is the first simple experimental evidence for low-energy generation. The performance is inversely proportional to the incident light intensity. The thermodynamic limit of conventional photovoltaic conversion is lower than 30%, while in the case of the mechanism reported here, it can be propelled above 60%. An optimization of the effect by a suitable conditioning and annealing should be possible, opening the way to different applications, especially in the areas of nanophotovoltaics and very high efficiency solar cells.

  3. RHIC low energy beam loss projections

    SciTech Connect

    Satogata,T.

    2009-08-01

    For RHIC low-energy operations, we plan to collide Au beams with energies of E = 2:5-10 GeV/u in RHIC. Beams are injected into collision optics, and RHIC runs as a storage ring with no acceleration. At these low energies, observed beam lifetimes are minutes, with measured beam lifetimes of 3.5 min (fast) and 50 min (slow) at E=4.6 GeV/u in the March 2008 test run. With these lifetimes we can operate RHIC as a storage ring to produce reasonable integrated luminosity. This note estimates beam losses and collimator/dump energy deposition in normal injection modes of low energy operation. The main question is whether a normal injection run is feasible for an FY10 10-15 week operations run from a radiation safety perspective. A peripheral question is whether continuous injection operations is feasible from a radiation safety perspective. In continuous injection mode, we fill both rings, then continuously extract and reinject the oldest bunches that have suffered the most beam loss to increase the overall integrated luminosity. We expect to gain a factor of 2-3 in integrated luminosity from continuous injection at lowest energies if implemented[1]. Continuous injection is feasible by FY11 from an engineering perspective given enough effort, but the required extra safety controls and hardware dose risk make it unappealing for the projected luminosity improvement. Low-energy electron cooling will reduce beam losses by at least an order of magnitude vs normal low-energy operations, but low energy cooling is only feasible in the FY13 timescale and therefore beyond the scope of this note. For normal injection low energy estimates we assume the following: (1) RHIC beam total energies are E=2.5-10 GeV/u. (Continuous injection mode is probably unnecessary above total energies of E=7-8 GeV/u.); (2) RHIC operates only as a storage ring, with no acceleration; (3) 110 bunches of about 0.5-1.0 x 10{sup 9} initial bunch intensities (50-100% injection efficiency, likely conservative

  4. Effects of Ion Implantation on in Vitro Pollen Germination and Cellular Organization of Pollen Tube in Pinus thunbergii Parl. (Japanese Black Pine)

    NASA Astrophysics Data System (ADS)

    Li, Guoping; Huang, Qunce; Yang, Lusheng; Dai, Ximei; Qin, Guangyong; Huo, Yuping

    2006-09-01

    Low-energy ion implantation, as a new technology to produce mutation in plant breeding, has been widely applied in agriculture in China. But so far there is a little understanding of the underlying mechanisms responsible for its biological effects at the cellular level. Here we report the biological effects of a nitrogen ion beams of 30 keV on the pollen grains of Pinus thunbergii Parl. In general, ion implantation inhibited pollen germination. The dose-response curve presented a particular saddle-like pattern. Ion implantation also changed the dimension of the elongated tubes and significantly induced tip swelling. Confocal microscopy indicated that the pollen tube tips in P. thunbergii contained an enriched network of microtubules. Ion implantation led to the disruption of microtubules especially in swollen tips. Treatment with colchicine demonstrated that tip swelling was caused by the disruption of microtubules in the tip, indicating a unique role for microtubules in maintaining the tip integrality of the pollen tube in conifer. Our results suggest that ion implantation induce the disruption of microtubule organization in pollen and pollen tubes and subsequently cause morphological abnormalities in the pollen tubes. This study may provide a clue for further investigation on the interaction between low-energy ion beams and pollen tube growth.

  5. Simulation of low-energy ion scattering

    NASA Astrophysics Data System (ADS)

    Langelaar, M. H.; Breeman, M.; Mijiritskii, A. V.; Boerma, D. O.

    A new simulation program `MATCH' has been developed for a detailed analysis of low-energy ion scattering (LEIS) and recoiling data. Instead of performing the full calculation of the three-dimensional trajectories through the sample from the ion source towards the detector, incoming trajectories as well as reversed-time outgoing trajectories are calculated, separately. Finally, these trajectories are matched to obtain the yield. The program has been tested for spectra and azimuthal scans of scattering and recoiling events of various sample species in different scattering geometries.

  6. Annihilation of Low Energy Antiprotons in Hydrogen

    SciTech Connect

    Ovchinnikov, S.Yu.; Macek, J.H.

    2003-08-26

    The cross sections for annihilation of antiprotons in hydrogen are very important for designing the High-Performance Antiproton Trap (HiPAT). When antiprotons are trapped they undergo atomic reactions with background gases which remove them from the trap. First, antiprotons are captured into highly excited bound states by ejecting the bound electrons, then they are radiationally deexcited and, finally, they annihilate by nuclear interaction. An understanding of these process require reliable cross sections for low-energy collisions of antiprotons with atoms. We have developed a theoretical technique for accurate calculations of these cross sections.

  7. The low energy booster project status

    SciTech Connect

    Tuttle, G.W.

    1993-05-01

    In order to achieve the required injection momentum, the Superconducting Super Collider (SSC) has an accelerator chain comprised of a Linear Accelerator and three synchrotrons. The Low Energy Booster (LEB) is the first synchrotron in this chain. The LEB project has made significant progress in the development of major subsystems and conventional construction. This paper briefly reviews the performance requirements of the LEB and describes significant achievements in each of the major subsystem areas. Highlighted among these achievements are the LEB foreign collaborations with the Budker Institute of Nuclear Physics (BINP) located in Novosibirsk, Russia.

  8. Low-energy ballistic lunar transfers

    NASA Astrophysics Data System (ADS)

    Parker, Jeffrey S.

    A systematic method is developed that uses dynamical systems theory to model, analyze, and construct low-energy ballistic lunar transfers (BLTs). It has been found that low-energy BLTs may be produced by intersecting the stable manifold of an unstable Earth-Moon three-body orbit with the Earth. A spacecraft following such a trajectory is only required to perform a single maneuver, namely, the Trans-Lunar Injection maneuver, in order to complete the transfer. After the Trans-Lunar Injection maneuver, the spacecraft follows an entirely ballistic trajectory that asymptotically approaches and arrives at the target lunar three-body orbit. Because these orbit transfers require no orbit insertion maneuver at the three-body orbit, the transfers may be used to send spacecraft 25--40% more massive than spacecraft sent to the same orbits via conventional, direct transfers. From the targeted three-body orbits, the spacecraft may transfer to nearly any region within the Earth-Moon system, including any location on the surface of the Moon. The systematic methods developed in this research allow low-energy BLTs to be characterized by six parameters. It has been found that BLTs exist in families, where a family of BLTs consists of transfers whose parameters vary in a continuous fashion from one end of the family to the other. The families are easily identified and studied using a BLT State Space Map (BLT Map). The present research studies BLT Maps and has surveyed a wide variety of BLTs that exist in the observed families. It has been found that many types of BLTs may be constructed between 185-km low Earth parking orbits and lunar three-body orbits that require less than 3.27 km/s and fewer than 120 days of transfer time. Under certain conditions, BLTs may be constructed that require less than 3.2 km/s and fewer than 100 days of transfer time. It has been found that BLTs may implement LEO parking orbits with nearly any combination of altitude and inclination; they may depart from

  9. Cochlear Implants.

    ERIC Educational Resources Information Center

    Clark, Catherine; Scott, Larry

    This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

  10. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    Welch, J.J.

    1984-12-01

    The measurement of naturally occurring radioisotopes whose half lives are less than a few hundred million years but more than a few years provides information about the temporal behavior of geologic and climatic processes, the temporal history of meteoritic bodies as well as the production mechanisms of these radioisotopes. A new extremely sensitive technique for measuring these radioisotopes at tandem Van de Graaff and cyclotron facilities has been very successful though the high cost and limited availability have been discouraging. We have built and tested a low energy cyclotron for radiocarbon dating similar in size to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity /sup 14/C measurements that are now done at accelerator facilities. We found that no significant background is present when the cyclotron is tuned to accelerate /sup 14/C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect /sup 14/C directly at modern concentrations. We show how a conventional carbon negative ion source, located outside the cyclotron magnet, would produce sufficient beam and provide for quick sampling to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

  11. Low Energy Nuclear Reactions: 2007 Update

    NASA Astrophysics Data System (ADS)

    Krivit, Steven B.

    2007-03-01

    This paper presents an overview of low energy nuclear reactions, a subset of the field of condensed matter nuclear science. Condensed matter nuclear science studies nuclear effects in and/or on condensed matter, including low energy nuclear reactions, an entirely new branch of science that gained widespread attention and notoriety beginning in 1989 with the announcement of a previously unrecognized source of energy by Martin Fleischmann and Stanley Pons that came to be known as cold fusion. Two branches of LENR are recognized. The first includes a set of reactions like those observed by Fleischmann and Pons that use palladium and deuterium and yield excess heat and helium-4. Numerous mechanisms have been proposed to explain these reactions, however there is no consensus for, or general acceptance of, any of the theories. The claim of fusion is still considered speculative and, as such, is not an ideal term for this work. The other branch is a wide assortment of nuclear reactions that may occur with either hydrogen or deuterium. Anomalous nuclear transmutations are reported that involve light as well as heavy elements. The significant questions that face this field of research are: 1) Are LENRs a genuine nuclear reaction? 2) If so, is there a release of excess energy? 3) If there is, is the energy release cost-effective?

  12. Modulation of low-energy cosmic rays

    NASA Technical Reports Server (NTRS)

    Sari, J. W.

    1975-01-01

    The relation between the diffusion coefficient of cosmic rays in the solar wind and the power spectrum of interplanetary magnetic field fluctuations, established in recent theories, is tested directly for low energy protons (below 80 MeV). In addition, an attempt is made to determine whether the particles are scattered by magnetic field discontinuities or by fluctuations between discontinuities. Predictions of a perturbation solution of the Fokker-Planck equation are compared with observations of the cosmic ray radial gradient. It is found that at energies between 40 and 80 MeV, galactic cosmic ray protons respond to changes in the predicted diffusion coefficients (i.e., the relationship under consideration holds at these low energies). The relation between changes in the proton flux and modulation parameters is best when the contribution of discontinuities is subtracted, which means that scattering is caused by fluctuations between discontinuities. There appears to be no distinct relation between changes in the modulation parameters and changes in the intensity of 20 to 40 MeV protons.

  13. Low energy neutrinos in Super-Kamiokande

    NASA Astrophysics Data System (ADS)

    Sekiya, Hiroyuki

    2016-05-01

    Super-Kamiokande (SK), a 50 kton water Cherenkov detector, observes 8B solar neutrinos via neutrino-electron elastic scattering. The analysis threshold was successfully lowered to 3.5 MeV (recoil electron kinetic energy) in SK-IV. To date SK has observed solar neutrinos for 18 years. An analysis regarding possible correlations between the solar neutrino flux and the 11 year solar activity cycle is shown. With large statistics, SK searches for distortions of the solar neutrino energy spectrum caused by the MSW resonance in the core of the sun. SK also searches for a day/night solar neutrino flux asymmetry induced by the matter in the Earth. The Super-Kamiokande Gd (SK-Gd) project is the upgrade of the SK detector via the addition of water-soluble gadolinium (Gd) salt. This modification will enable it to efficiently identify low energy anti-neutrinos. SK-Gd will pursue low energy physics currently inaccessible to SK due to backgrounds. The most important will be the world’s first observation of the diffuse supernova neutrino background. The main R&D program towards SK-Gd is EG ADS: a 200 ton, fully instrumented tank built in a new cavern in the Kamioka mine.

  14. Low Energy Ion-Molecule Reactions

    SciTech Connect

    James M. Farrar

    2004-05-01

    This objective of this project is to study the dynamics of the interactions of low energy ions important in combustion with small molecules in the gas phase and with liquid hydrocarbon surfaces. The first of these topics is a long-standing project in our laboratory devoted to probing the key features of potential energy surfaces that control chemical reactivity. The project provides detailed information on the utilization of specific forms of incident energy, the role of preferred reagent geometries, and the disposal of total reaction energy into product degrees of freedom. We employ crossed molecular beam methods under single collision conditions, at collision energies from below one eV to several eV, to probe potential surfaces over a broad range of distances and interaction energies. These studies allow us to test and validate dynamical models describing chemical reactivity. Measurements of energy and angular distributions of the reaction products with vibrational state resolution provide the key data for these studies. We employ the crossed beam low energy mass spectrometry methods that we have developed over the last several years.

  15. Inhibition of aqueous degradation of Y1Ba2Cu3O7 - x high-Tc superconductor by nitrogen ion implantation

    NASA Astrophysics Data System (ADS)

    Chaudhari, S. M.; Viswanathan, R.; Bendre, S. T.; Nawale, P. P.; Kanetkar, S. M.; Ogale, S. B.

    1989-11-01

    The influence of 60-keV N+2 ion implantation on the aqueous degradation of the Y1Ba2Cu3O7-x high-Tc superconductor is studied by the small-angle x-ray diffraction technique. Structural depth profiling is performed by registering the x-ray data at several small angles of incidence between 0.3° and 10.0° within Seeman-Bohlin geometry. Examination of samples implanted at a dose value of 3×1017 ions/cm2 and subjected to different aqueous treatments reveals that implantation arrests the degradation process and imparts structural stability to the superconductor. Resistivity temperature data are also provided for specific cases of interest.

  16. Inhibition of aqueous degradation of Y sub 1 Ba sub 2 Cu sub 3 O sub 7 minus x high- T sub c superconductor by nitrogen ion implantation

    SciTech Connect

    Chaudhari, S.M.; Viswanathan, R.; Bendre, S.T.; Nawale, P.P.; Kanetkar, S.M.; Ogale, S.B. )

    1989-11-01

    The influence of 60-keV N{sup +}{sub 2} ion implantation on the aqueous degradation of the Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} high-{ital T}{sub {ital c}} superconductor is studied by the small-angle x-ray diffraction technique. Structural depth profiling is performed by registering the x-ray data at several small angles of incidence between 0.3{degree} and 10.0{degree} within Seeman--Bohlin geometry. Examination of samples implanted at a dose value of 3{times}10{sup 17} ions/cm{sup 2} and subjected to different aqueous treatments reveals that implantation arrests the degradation process and imparts structural stability to the superconductor. Resistivity temperature data are also provided for specific cases of interest.

  17. Revamping existing ammonia plants with a new low-energy process

    SciTech Connect

    Banquy, D.

    1984-01-01

    In this process, only part of the natural gas feed is treated in the primary reformer, and the rest is reformed directly in the secondary reformer using excess air. The excess nitrogen is removed in a cryogenic separation upstream of the synthesis loop. The features of this new low energy ammonia process, and the related advantages in terms of energy savings, make it suitable for revamping existing ammonia plants, with attractive economics.

  18. Low Energy Antiproton Experiments - A Review

    SciTech Connect

    Jungmann, Klaus P.

    2005-10-19

    Low energy antiprotons offer excellent opportunities to study properties of fundamental forces and symmetries in nature. Experiments with them can contribute substantially to deepen our fundamental knowledge in atomic, nuclear and particle physics. Searches for new interactions can be carried out by studying discrete symmetries. Known interactions can be tested precisely and fundamental constants can be extracted from accurate measurements on free antiprotons (p-bar's) and bound two- and three-body systems such as antihydrogen (H-bar = p-bare-), the antprotonic helium ion (He++p-bar)+ and the antiprotonic atomcule (He++p-bare-) . The trapping of a single p-bar in a Penning trap, the formation and precise studies of antiprotonic helium ions and atoms and recently the production of H-bar have been among the pioneering experiments. They have led already to precise values for p-bar parameters, accurate tests of bound two- and three-body Quantum Electrodynamics (QED), tests of the CPT theorem and a better understanding of atom formation from their constituents. Future experiments promise more precise tests of the standard theory and have a robust potential to discover new physics. Precision experiments with low energy p-bar's share the need for intense particle sources and the need for time to develop novel instrumentation with all other experiments, which aim for high precision in exotic fundamental systems. The experimental programs - carried out in the past mostly at the former LEAR facility and at present at the AD facility at CERN - would benefit from intense future sources of low energy p-bar's. The highest possible p-bar fluxes should be aimed for at new facilities such as the planned FLAIR facility at GSI in order to maximize the potential of delicate precision experiments to influence model building. Examples of key p-bar experiments are discussed here and compared with other experiments in the field. Among the central issues is their potential to obtain

  19. Atomic ionization by neutrinos at low energies

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-Pang

    2016-05-01

    It is well-known that neutrino-electron scattering at low recoil energies provides sensitivity gain in constraining neutrinos’ magnetic moments and their possible milli-charges. However, in detectors with sub-keV thresholds, the binding effects of electrons become significant. In this talk, we present our recent works of applying ab initio calculations to germanium ionization by neutrinos at low energies. Compared with the conventional differential cross section formulae that were used to derive current experimental bounds, our results with less theoretical uncertainties set a more reliable bound on the neutrino magnetic moment and a more stringent bound on the neutrino milli-charge with current reactor antineutrino data taken from germanium detectors.

  20. Computational Study of Low Energy Nuclear Scattering

    NASA Astrophysics Data System (ADS)

    Salazar, Justin; Hira, Ajit; Brownrigg, Clifton; Pacheco, Jose

    2013-04-01

    We continue our interest in the interactions between different nuclear species with a computational study of the scattering of the low-energy nuclei of H through F atoms ( Z<=9 ) from Palladium and other metals. First, a FORTRAN computer program was developed to compute stopping cross sections and scattering angles in Pd and other metals for the small nuclear projectiles, using Monte Carlo calculation. This code allows for different angles of incidence. Next, simulations were done in the energy interval from 10 to 140kev. The computational results thus obtained are compared with relevant experimental data. The data are further analyzed to identify periodic trends in terms of the atomic number of the projectile. Such studies have potential applications in nuclear physics and in nuclear medicine.

  1. RHIC low energy tests and initial operations

    SciTech Connect

    Satogata,T.; Ahrens, L.; Bai, M.; Brennan, J.M.; Bruno, D.; Butler, J.; Drees, A.; Fedotov, A.; Fischer, W.; Harvey, M.; Hayes, T.; Jappe, W.; Lee, R.C.; Mackay, W.W.; Malitsky, N.; Marr, G.; Michnoff, R.; Oerter, B.; Pozdeyev, E.; Roser, T.; Severino, F.; Smith, K.; Tepikian, S.; Tsoupas, N.

    2009-05-04

    Future Relativistic Heavy Ion Collider (RHIC) runs, including a portion of FY10 heavy ion operations, will explore collisions at center of mass energies of 5-50 GeV/n (GeV/nucleon). Operations at these energies is motivated by a search for the QCD phase transition critical point. The lowest end of this energy range is nearly a factor of four below the nominal RHIC injection center of mass energy of {radical} s = 20.8 GeV/n. There are several operational challenges in the RHIC low-energy regime, including harmonic number changes, small longitudinal acceptance, lowered magnet field quality, nonlinear orbit control, and luminosity monitoring. We report on the experience with some of these challenges during beam tests with gold in March 2008, including first RHIC operations at {radical}s = 9.18 GeV/n and first beam experience at {radical}s = 5 GeV/n.

  2. Phenomenological implications of low energy supersymmetry breaking

    SciTech Connect

    Dimopoulos, S. |; Dine, M.; Raby, S.; Thomas, S.; Wells, J.D.

    1996-07-01

    The experimental signatures for low energy supersymmetry breaking are presented. The lightest standard model superpartner is unstable and decays to its partner plus a Goldstino, G. For a supersymmetry breaking scale below a few 1,000 TeV this decay can take place within a detector, leading to very distinctive signatures. If a neutralino is the lightest standard model superpartner it decays by {chi}{sub 1}{sup 0} {r_arrow} {gamma} + G, and if kinematically accessible by {chi}{sub 1}{sup 0} {r_arrow} (Z{sup 0}, h{sup 0}, H{sup 0}, A{sup 0}) + G. These decays can give rise to displaced vertices. Alternately, if a slepton is the lightest standard model superpartner it decays by {tilde l} {r_arrow} l + G. This can be seen as a greater than minimum ionizing charged particle track, possibly with a kink to a minimum ionizing track.

  3. Low-energy neutral-atom spectrometer

    SciTech Connect

    Voss, D.E.; Cohen, S.A.

    1982-04-01

    The design, calibration, and performance of a low energy neutral atom spectrometer are described. Time-of-flight analysis is used to measure the energy spectrum of charge-exchange deuterium atoms emitted from the PLT tokamak plasma in the energy range from 20 to 1000 eV. The neutral outflux is gated on a 1 ..mu..sec time scale by a slotted rotating chopper disc, supported against gravity in vacuum by magnetic levitation, and is detected by secondary electron emission from a Cu-Be plate. The energy dependent detection efficiency has been measured in particle beam experiments and on the tokamak so that the diagnostic is absolutely calibrated, allowing quantitative particle fluxes to be determined with 200 ..mu..sec time resolution. In addition to its present application as a plasma diagnostic, the instrument is capable of making a wide variety of measurements relevant to atomic and surface physics.

  4. Low-energy pion-nucleon scattering

    NASA Astrophysics Data System (ADS)

    Gibbs, W. R.; Ai, Li; Kaufmann, W. B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent π+/-p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f2=0.0756+/-0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P31 and P13 partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the Σ term. Off-shell amplitudes are also provided.

  5. Low-energy pion-nucleon scattering

    SciTech Connect

    Gibbs, W.R.; Ai, L.; Kaufmann, W.B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent {pi}{sup {plus_minus}}p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f{sup 2}=0.0756{plus_minus}0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P{sub 31} and P{sub 13} partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the {Sigma} term. Off-shell amplitudes are also provided. {copyright} {ital 1998} {ital The American Physical Society}

  6. Low energy ion-molecule reactions

    SciTech Connect

    Farrar, J.M.

    1993-12-01

    This project is concerned with elucidating the dynamics of elementary ion-molecule reactions at collision energies near and below 1 eV. From measurements of the angular and energy distributions of the reaction products, one can infer intimathe details about the nature of collisions leading to chemical reaction, the geometries and lifetimes of intermediate complexes that govern the reaction dynamics, and the collision energy dependence of these dynamical features. The author employs crossed-beam low energy mass spectrometry technology developed over the last several years, with the focus of current research on proton transfer and hydrogen atom transfer reactions of te O{sup {minus}} ion with species such as HF, H{sub 2}O, and NH{sub 3}.

  7. Low energy dislocation structures in epitaxy

    NASA Technical Reports Server (NTRS)

    Van Der Merwe, Jan H.; Woltersdorf, J.; Jesser, W. A.

    1986-01-01

    The principle of minimum energy was applied to epitaxial interfaces to show the interrelationship beteen misfit, overgrowth thickness and misfit dislocation spacing. The low energy dislocation configurations were presented for selected interfacial geometries. A review of the interfacial energy calculations was made and a critical assessment of the agreement between theory and experiment was presented. Modes of misfit accommodation were presented with emphasis on the distinction between kinetic effects and equilibrium conditions. Two-dimensional and three-dimensional overgrowths were treated together with interdiffusion-modified interfaces, and several models of interfacial structure were treated including the classical and the current models. The paper is concluded by indicating areas of needed investigation into interfacial structure.

  8. Low energy consumption spintronics using multiferroic heterostructures

    NASA Astrophysics Data System (ADS)

    Trassin, Morgan

    2016-01-01

    We review the recent progress in the field of multiferroic magnetoelectric heterostructures. The lack of single phase multiferroic candidates exhibiting simultaneously strong and coupled magnetic and ferroelectric orders led to an increased effort into the development of artificial multiferroic heterostructures in which these orders are combined by assembling different materials. The magnetoelectric coupling emerging from the created interface between the ferroelectric and ferromagnetic layers can result in electrically tunable magnetic transition temperature, magnetic anisotropy or magnetization reversal. The full potential of low energy consumption magnetic based devices for spintronics lies in our understanding of the magnetoelectric coupling at the scale of the ferroic domains. Although the thin film synthesis progresses resulted into the complete control of ferroic domain ordering using epitaxial strain, the local observation of magnetoelectric coupling remains challenging. The ability to imprint ferroelectric domains into ferromagnets and to manipulate those solely using electric fields suggests new technological advances for spintronics such as magnetoelectric memories or memristors.

  9. Low-energy neutrino factory design

    SciTech Connect

    Ankenbrandt, C.; Bogacz, S.A.; Bross, A.; Geer, S.; Johnstone, C.; Neuffer, D.; Popovic, M.; /Fermilab

    2009-07-01

    The design of a low-energy (4 GeV) neutrino factory (NF) is described, along with its expected performance. The neutrino factory uses a high-energy proton beam to produce charged pions. The {pi}{sup {+-}} decay to produce muons ({mu}{sup {+-}}), which are collected, accelerated, and stored in a ring with long straight sections. Muons decaying in the straight sections produce neutrino beams. The scheme is based on previous designs for higher energy neutrino factories, but has an improved bunching and phase rotation system, and new acceleration, storage ring, and detector schemes tailored to the needs of the lower energy facility. Our simulations suggest that the NF scheme we describe can produce neutrino beams generated by {approx} 1.4 x 10{sup 21} {mu}{sup +} per year decaying in a long straight section of the storage ring, and a similar number of {mu}{sup -} decays.

  10. Low energy high pressure miniature screw valve

    DOEpatents

    Fischer, Gary J.; Spletzer, Barry L.

    2006-12-12

    A low energy high pressure screw valve having a valve body having an upper portion and a lower portion, said lower portion of said valve body defining an inlet flow passage and an outlet flow passage traversing said valve body to a valve seat, said upper portion of said valve body defining a cavity at said valve seat, a diaphragm restricting flow between said upper portion of said valve body and said lower portion, said diaphragm capable of engaging said valve seat to restrict fluid communication between said inlet passage and said outlet passage, a plunger within said cavity supporting said diaphragm, said plunger being capable of engaging said diaphragm with said valve seat at said inlet and outlet fluid passages, said plunger being in point contact with a drive screw having threads engaged with opposing threads within said upper portion of said valve body such engagement allowing motion of said drive screw within said valve body.

  11. Low energy particle signature of substorm dipolarization

    SciTech Connect

    Liu, C.; Perez, J.D. ); Moore, T.E.; Chappell, C.R. )

    1994-02-01

    The low energy particle signature of substorm dipolarization is exhibited through a case study of RIMS data on DE-1 at [approximately]2100 MLT, ILAT = 59[degrees][approximately]65[degrees], L = 3.8 [approximately] 5.4 R[sub E], and geocentric distances 2.6[approximately]2.9 R[sub E]. A strong cross-field-line, poleward outflow that lasts for a few minutes with a velocity that reaches at least 50 km/s is correlated with substorm activity evidenced in the AE index and the MAG-1 data. All the major species (H[sup +], He[sup +], O[sup +]) are observed to have the same bulk velocity. The parallel velocities are strongly correlated with the perpendicular velocities. The parallel acceleration is shown to result from the centrifugal force of the ExB drift induced by the dipolarizing perturbation of the magnetic field. 9 refs., 4 figs.

  12. Particle Settling in Low Energy Turbulence

    NASA Astrophysics Data System (ADS)

    Allen, Rachel; MacVean, Lissa; Tse, Ian; Mazzaro, Laura; Stacey, Mark; Variano, Evan

    2014-11-01

    Particle settling velocities can be altered by turbulence. In turbulence, dense particles may get trapped in convergent flow regions, and falling particles may be swept towards the downward side of turbulent eddies, resulting in enhanced settling velocities. The degree of velocity enhancement may depend on the Stokes number, the Rouse number, and the turbulent Reynolds number. In a homogeneous, isotropic turbulence tank, we tested the effects of particle size and type, suspended sediment concentration, and level of turbulence on the settling velocities of particles typically found in muddy estuaries. Two Acoustic Doppler Velocimeters (ADVs), separated vertically, measured turbulent velocities and suspended sediment concentrations, which yield condition dependent settling velocities, via ∂/á C ñ ∂ t = -∂/∂ z (ws á C ñ + á w ' C ' ñ) . These results are pertinent to fine sediment transport in estuaries, where high concentrations of suspended material are transported and impacted by low energy turbulence.

  13. Low energy demonstration accelerator technical area 53

    SciTech Connect

    1996-04-01

    As part of the Department of Energy`s (DOE) need to maintain the capability of producing tritium in support of its historic and near-term stewardship of the nation`s nuclear weapons stockpile, the agency has recently completed a Programmatic Environmental Impact Statement for Tritium Supply and Recycling. The resulting Record of Decision (ROD) determined that over the next three years the DOE would follow a dual-track acquisition strategy that assures tritium production for the nuclear weapon stockpile in a rapid, cost effective, and safe manner. Under this strategy the DOE will further investigate and compare two options for producing tritium: (1) purchase of an existing commercial light-water reactor or irradiation services with an option to purchase the reactor for conversion to a defense facility; and (2) design, build, and test critical components of a system for accelerator production of tritium (APT). The final decision to select the primary production option will be made by the Secretary of Energy in the October 1998 time frame. The alternative not chosen as the primary production method, if feasible, would be developed as a back-up tritium supply source. This Environmental Assessment (EA) analyzes the potential environmental effects that would be expected to occur if the DOE were to design, build, and test critical prototypical components of the accelerator system for tritium production, specifically the front-end low-energy section of the accelerator, at Los Alamos National Laboratory. The Low Energy Demonstration Accelerator (LEDA) would be incrementally developed and tested in five separate stages over the next seven years. The following issues were evaluated for the proposed action: utility demands, air, human health, environmental restoration, waste management, transportation, water, threatened and endangered species, wetlands, cultural resources, and environmental justice.

  14. Low energy AMS of americium and curium

    NASA Astrophysics Data System (ADS)

    Christl, Marcus; Dai, Xiongxin; Lachner, Johannes; Kramer-Tremblay, Sheila; Synal, Hans-Arno

    2014-07-01

    Accelerator mass spectrometry (AMS) has evolved over the past years as one of the most sensitive, selective, and robust techniques for actinide analyses. While analyses of U and Pu isotopes have already become routine at the ETH Zurich 0.5 MV AMS system "Tandy", there is an increasing demand for highly sensitive analyses of the higher actinides such as Am and Cm for bioassay applications and beyond. In order to extend the actinide capabilities of the compact ETH Zurich AMS system and to develop new, more sensitive bioassay routines, a pilot study was carried out. The aim was to investigate and document the performance and the potential background of Am and Cm analyses with low energy AMS. Our results show that 241Am and Cm isotopes can be determined relative to a 243Am tracer if samples and AMS standards are prepared identically with regard to the matrix elements, in which the sample is dispersed. In this first test, detection limits for Cm and Am isotopes are all in the sub-femtogram range and even below 100 ag for Cm isotopes. In a systematic background study in the mass range of the Cm isotopes, two formerly unknown metastable triply charged Th molecules were found on amu(244) and amu(248). The presence of such a background is not a principal problem for AMS if the stripper pressure is increased accordingly. Based on our first results, we conclude that ultra-trace analyses of Am and Cm isotopes for bioassay are very well possible with low energy AMS.

  15. The Low Energy Effective Area of the Chandra Low Energy Transmission Grating Spectrograph

    NASA Technical Reports Server (NTRS)

    Pease, D.; Drake, J. J.; Johnson, C. O.; Kashya, V.; Ratzlaff, P. W.; Wargelin, B. J.; Brinkman, A. C.; Kaastra, J. S.; vanderMeer, R.; Paerels, F. B.

    2000-01-01

    The Chandra X-ray Observatory was successfully launched on July 23, 1999, and subsequently began an intensive calibration phase. We present the preliminary results from the in-flight calibration of the low energy response of the High Resolution Camera spectroscopic readout (HRC-S) combined with the Low Energy Transmission Grating (LETG) aboard Chandra. These instruments comprise the Low Energy Transmission Grating Spectrograph (LETGS). For this calibration study, we employ a pure hydrogen non-LTE white dwarf emission model (T = 25000 K and log g = 9.0) for comparison with the Chandra observations of Sirius B. The pre-flight calibration of the LETGS effective area only covered wavelengths shortward of 44 A (E less than 277 eV). Our Sirius B analysis shows that the HRC-S quantum efficiency (QE) model assumed for longer wavelengths leads to an overestimate of the effective area by an average factor of about 1.6. We derive a correction to the low energy HRC-S QE model to match the predicted and observed Sirius B spectra over the wavelength range of 44-185 A. We make an independent test of our results by the comparison of a Chandra LETGS observation of HZ 43 with pure hydrogen model atmosphere predictions and find good agreement.

  16. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  17. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  18. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  19. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  20. 21 CFR 878.4410 - Low energy ultrasound wound cleaner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Low energy ultrasound wound cleaner. 878.4410... (CONTINUED) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4410 Low energy ultrasound wound cleaner. (a) Identification. A low energy ultrasound wound cleaner is a device that...

  1. Positron implantation in solids

    SciTech Connect

    Ghosh, V.J.; Lynn, K.G.; Welch, D.O.

    1993-12-31

    The Monte Carlo technique for modeling positron prior to annihilation and electron implantation in semi-infinite metals is described. Particle implantation is modelled as a multistep process, a series of collisions with the atoms of the host material. In elastic collisions with neutral atoms there is no transfer of energy. The particle loses energy by several different channels, excitation of the electron gas, ionization of the ion cores, or, at low energies, by phonon excitation. These competing scattering mechanisms have been incorporated into the Monte Carlo framework and several different models are being used. Brief descriptions of these Monte Carlo schemes, as well as an analytic model for positron implantation are included. Results of the Monte Carlo simulations are presented and compared with expermental data. Problems associated with modeling positron implantation are discuss and the need for more expermental data on energy-loss in different materials is stressed. Positron implantation in multilayers of different metals is briefly described and extensions of this work to include a study of multilayers and heterostructures is suggested.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    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.

  4. Novel results on low energy neutrino physics

    NASA Astrophysics Data System (ADS)

    Bellini, Gianpaolo

    2012-07-01

    Many progresses have been achieved in the study of low energy neutrinos from Sun and Earth. In the solar neutrinos the flux from 7Be has been measured with a total error <5% (introducing strong constraints also on the pp flux), while the day/night effect in that energy region has been determined at 1%. The 8B neutrinos have been detected with a threshold down to 3 MeV, while the solar neutrinos flux from pep reaction has been measured together with a stringent limit on CNO. These results give the experimental proof of the neutrino oscillation in vacuum and the validation of the MSW-LMA model in that region, while the day/night allows the isolation of the LMA solution by means of the solar neutrinos only, without the assumption of CPT symmetry. The evidence of the antineutrinos produced within the Earth by radioactive decays is now very robust, but more statistics is needed to clearly estimate the radiogenic contribution to the terrestrial caloric energy.

  5. Low-energy positron interactions with xenon

    NASA Astrophysics Data System (ADS)

    Machacek, J. R.; Makochekanwa, C.; Jones, A. C. L.; Caradonna, P.; Slaughter, D. S.; McEachran, R. P.; Sullivan, J. P.; Buckman, S. J.; Bellm, S.; Lohmann, B.; Fursa, D. V.; Bray, I.; Mueller, D. W.; Stauffer, A. D.

    2011-12-01

    Low-energy interactions of positrons with xenon have been studied both experimentally and theoretically. The experimental measurements were carried out using a trap-based positron beam with an energy resolution of ˜80 meV, while the theoretical calculations were carried out using the convergent close-coupling method and the relativistic optical potential approach. Absolute values of the grand total, positronium formation and grand total minus positronium formation cross sections are presented over the energy range of 1-60 eV. Elastic differential cross sections (DCS), for selected energies, are also presented both below and above the positronium formation threshold. Fine energy-step measurements of the positronium formation cross section over the energy range of 4.4-8.4 eV, and measurements of the elastic DCS at the energies of 5.33 and 6.64 eV, have been carried out to investigate the ionization threshold regions corresponding to the 2P3/2 and 2P1/2 states of the Xe+ ion. The present results are compared with both experimental and theoretical values from the literature where available.

  6. Low energy scattering with a nontrivial pion

    SciTech Connect

    Fariborz, Amir H.

    2007-12-01

    An earlier calculation in a generalized linear sigma model showed that the well-known current algebra formula for low energy pion-pion scattering held even though the massless Nambu Goldstone pion contained a small admixture of a two-quark two-antiquark field. Here we turn on the pion mass and note that the current algebra formula no longer holds exactly. We discuss this small deviation and also study the effects of a SU(3) symmetric quark mass type term on the masses and mixings of the eight SU(3) multiplets in the model. We calculate the s-wave scattering lengths, including the beyond current algebra theorem corrections due to the scalar mesons, and observe that the effect of the scalar mesons is to improve the agreement with experiment. In the process, we uncover the way in which linear sigma models give controlled corrections (due to the presence of scalar mesons) to the current algebra scattering formula. Such a feature is commonly thought to exist only in the nonlinear sigma model approach.

  7. Studies in Low-Energy Nuclear Science

    SciTech Connect

    Brune, Carl R; Grimes, Steven M

    2006-03-30

    This report presents a summary of research projects in the area of low energy nuclear reactions and structure, carried out between 1 January 2003 and 31 December 2005 and supported by U.S. DOE grant number DE-FG03-03NA00074. Cross sections measured with high resolution have been subjected to an Ericson theory analysis to infer information about the nuclear level density. Other measurements were made of the spectral shape of particles produced in evaporation processes; these also yield level density information. A major project was the development of a new Hauser-Feshbach code for analyzing such spectra. Other measurements produced information on the spectra of gamma rays emitted in reactions on heavy nuclei and gave a means of refining our understanding of gamma-ray strength functions. Finally,reactions on light nuclei were studied and subjected to an R-matrix analysis. Cross sections fora network of nuclear reactions proceedingthrough a given compound nucleus shouldgreatly constrain the family of allowed parameters. Modifications to the formalism andcomputer code are also discussed.

  8. Low-energy electron collisions with biomolecules

    NASA Astrophysics Data System (ADS)

    Winstead, Carl; McKoy, Vincent

    2012-11-01

    We report recent progress in applying the Schwinger multichannel computational method to the interactions of slow electrons with biomolecules. Calculations on constituents of DNA, including nucleobases, phosphate esters, and models of the backbone sugar, have provided insight into the nature of the low-energy shape resonances, and thereby into possible sites and mechanisms for electron attachment that may lead to strand-breaking. At the same time, more approximate calculations on larger assemblies such as nucleosides and deoxyadenosine monophosphate indicate how the resonance properties of the subunits will or will not persist in DNA itself. We are pursuing a similar strategy for another major class of biomolecules, the proteins, by beginning with fixed-nuclei studies of the constituent amino acids; here we present preliminary results for the simplest amino acid, glycine. We also describe efforts directed at an improved understanding electron collisions with alcohols, which, in addition to basic scientific interest, may prove useful in the modeling of ignition and combustion within biofuel-powered engines.

  9. Low energy CMOS for space applications

    NASA Technical Reports Server (NTRS)

    Panwar, Ramesh; Alkalaj, Leon

    1992-01-01

    The current focus of NASA's space flight programs reflects a new thrust towards smaller, less costly, and more frequent space missions, when compared to missions such as Galileo, Magellan, or Cassini. Recently, the concept of a microspacecraft was proposed. In this concept, a small, compact spacecraft that weighs tens of kilograms performs focused scientific objectives such as imaging. Similarly, a Mars Lander micro-rover project is under study that will allow miniature robots weighing less than seven kilograms to explore the Martian surface. To bring the microspacecraft and microrover ideas to fruition, one will have to leverage compact 3D multi-chip module-based multiprocessors (MCM) technologies. Low energy CMOS will become increasingly important because of the thermodynamic considerations in cooling compact 3D MCM implementations and also from considerations of the power budget for space applications. In this paper, we show how the operating voltage is related to the threshold voltage of the CMOS transistors for accomplishing a task in VLSI with minimal energy. We also derive expressions for the noise margins at the optimal operating point. We then look at a low voltage CMOS (LVCMOS) technology developed at Stanford University which improves the power consumption over conventional CMOS by a couple of orders of magnitude and consider the suitability of the technology for space applications by characterizing its SEU immunity.

  10. Oscillations of very low energy atmospheric neutrinos

    SciTech Connect

    Peres, Orlando L. G.; Smirnov, A. Yu.

    2009-06-01

    There are several new features in the production, oscillations, and detection of the atmospheric neutrinos of low energies E < or approx. 100 MeV. The flavor ratio r of muon to electron neutrino fluxes is substantially smaller than 2 and decreases with energy, a significant part of events is due to the decay of invisible muons at rest, etc. Oscillations in a two-layer medium (atmosphere-Earth) should be taken into account. We derive analytical and semianalytical expressions for the oscillation probabilities of these 'sub-sub-GeV' neutrinos. The energy spectra of the e-like events in water Cherenkov detectors are computed, and the dependence of the spectra on the 2-3 mixing angle {theta}{sub 23}, the 1-3 mixing, and the CP-violation phase are studied. We find that variations of {theta}{sub 23} in the presently allowed region change the number of e-like events by about 15%-20% as well as lead to distortion of the energy spectrum. The 1-3 mixing and CP violation can lead to {approx}10% effects. Detailed study of the sub-sub-GeV neutrinos will be possible in future megaton-scale detectors.