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Sample records for linear ion crystals

  1. Rare earth ion doped non linear laser crystals

    NASA Astrophysics Data System (ADS)

    Jaque, D.; Romero, J. J.; Ramirez, M. O.; Garcia, J. A. S.; de Las Heras, C.; Bausa, L. E.; Sole, J. G.

    2003-01-01

    We show how non linear crystals activated with Yb3+ or Nd3+ ions can be used to develop diode pumped solid state lasers emitting in the visible region of the electromagnetic spectrum. For this purpose we have selected relevant examples of systems investigated in our laboratory.

  2. Ejection of Coulomb Crystals from a Linear Paul Ion Trap for Ion-Molecule Reaction Studies.

    PubMed

    Meyer, K A E; Pollum, L L; Petralia, L S; Tauschinsky, A; Rennick, C J; Softley, T P; Heazlewood, B R

    2015-12-17

    Coulomb crystals are being increasingly employed as a highly localized source of cold ions for the study of ion-molecule chemical reactions. To extend the scope of reactions that can be studied in Coulomb crystals-from simple reactions involving laser-cooled atomic ions, to more complex systems where molecular reactants give rise to multiple product channels-sensitive product detection methodologies are required. The use of a digital ion trap (DIT) and a new damped cosine trap (DCT) are described, which facilitate the ejection of Coulomb-crystallized ions onto an external detector for the recording of time-of-flight (TOF) mass spectra. This enables the examination of reaction dynamics and kinetics between Coulomb-crystallized ions and neutral molecules: ionic products are typically cotrapped, thus ejecting the crystal onto an external detector reveals the masses, identities, and quantities of all ionic species at a selected point in the reaction. Two reaction systems are examined: the reaction of Ca(+) with deuterated isotopologues of water, and the charge exchange between cotrapped Xe(+) with deuterated isotopologues of ammonia. These reactions are examples of two distinct types of experiment, the first involving direct reaction of the laser-cooled ions, and the second involving reaction of sympathetically-cooled heavy ions to form a mixture of light product ions. Extensive simulations are conducted to interpret experimental results and calculate optimal operating parameters, facilitating a comparison between the DIT and DCT approaches. The simulations also demonstrate a correlation between crystal shape and image shape on the detector, suggesting a possible means for determining crystal geometry for nonfluorescing ions. PMID:26406306

  3. Hopping of an impurity defect in ion crystals in linear traps

    NASA Astrophysics Data System (ADS)

    Liang, J.; Haljan, P. C.

    2011-06-01

    Laser-cooled arrays or crystals of Yb171+ ions containing a single impurity, Yb172+ isotope, are confined in a linear radio-frequency Paul trap. Site-to-site hopping of the impurity ion, distinguished by a lack of fluorescence, is studied as a function of the Yb171+ laser-cooling parameters and as a function of the anisotropy of the trapping potential. Imaging of the independently resolved crystal sites permits the extraction of the impurity’s hopping trajectory, from which the dwell times at a given site can be obtained as well as the spatial distribution of hopping rate and hopping destination. The onset of rapid hopping is found to occur at average thermal energies approaching a significant fraction of the Coulomb potential energy. Furthermore, the hopping rate is enhanced at trap anisotropies near the critical value for the structural phase transition to a two-dimensional zigzag phase. Finally, the hopping mobility of the impurity ion is observed to be highest near the center of the crystal, which may have an intrinsic cause related to the crystal structure and dynamics near the zigzag transition.

  4. HEAVY ION LINEAR ACCELERATOR

    DOEpatents

    Van Atta, C.M.; Beringer, R.; Smith, L.

    1959-01-01

    A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.

  5. Heat transport through ion crystals

    NASA Astrophysics Data System (ADS)

    Freitas, Nahuel; Martinez, Esteban A.; Paz, Juan Pablo

    2016-01-01

    We study the thermodynamical properties of crystals of trapped ions which are laser cooled to two different temperatures in two separate regions. We show that these properties strongly depend on the structure of the ion crystal. Such structure can be changed by varying the trap parameters and undergoes a series of phase transitions from linear to zig-zag or helicoidal configurations. Thus, we show that these systems are ideal candidates to observe and control the transition from anomalous to normal heat transport. All structures behave as ‘heat superconductors’, with a thermal conductivity increasing linearly with system size and a vanishing thermal gradient inside the system. However, zig-zag and helicoidal crystals turn out to be hyper sensitive to disorder having a linear temperature profile and a length independent conductivity. Interestingly, disordered 2D ion crystals are heat insulators. Sensitivity to disorder is much smaller in the 1D case.

  6. Isospaced linear ion strings

    NASA Astrophysics Data System (ADS)

    Johanning, Michael

    2016-04-01

    We describe the statical and dynamical properties of strings of ions stored in segmented electrodynamical Paul traps with a uniform ion separation. In this work, this specific ion arrangement is achieved by a smooth anharmonic effective potential generated by suitable voltages applied to segmented dc electrodes or by appropriate electrode shaping. We find analytic expressions for the required field, potential and normal mode matrix and find that even finite systems closely reproduce the critical radial binding strength of an infinite size system at the transition from linear to zigzag configuration. From the normal mode matrix, we find that such strings exhibit a solid-state-like band of normal modes and determine the effective spin-spin coupling when the ion string is exposed to a magnetic gradient. We show how the potential, modes and couplings can be altered while still maintaining a homogeneous spacing and present numerical examples, for how this potential can be achieved in either segmented Paul traps or by using an optimized electrode geometry.

  7. Ion Coulomb crystals

    NASA Astrophysics Data System (ADS)

    Drewsen, Michael

    2015-03-01

    The following text will give a brief introduction to the physics of the spatially ordered structures, so-called Coulomb crystals, that appear when confined ions are cooled to sufficiently low temperatures. It will as well briefly comment on the very diverse scientific applications of such crystals, which have emerged the past two decades. While this document lacks figures, it includes a substantial number of references in which more detailed information can be found. It is the hope that the text will stimulate the reader to dig deeper into one or more of the discussed subjects and inspire her/him to think about new potential applications.

  8. Characterization of ion Coulomb crystals for fundamental sciences

    NASA Astrophysics Data System (ADS)

    Okada, Kunihiro; Ichikawa, Masanari; Wada, Michiharu

    2015-11-01

    We performed classical molecular dynamics (MD) simulations in order to search the conditions for efficient sympathetic cooling of highly charged ions (HCIs) in a linear Paul trap. Small two-component ion Coulomb crystals consisting of laser-cooled ions and HCIs were characterized by the results of the MD simulations. We found that the spatial distribution is determined by not only the charge-to-mass ratio but also the space charge effect. Moreover, the simulation results suggest that the temperature of HCIs do not necessarily decrease with increasing the number of laser-cooled ions in the cases of linear ion crystals. We also determined the cooling limit of sympathetically cooled 165Ho14+ ions in small linear ion Coulomb crystals. The present results show that sub-milli-Kelvin temperatures of at least 10 Ho14+ ions will be achieved by sympathetic cooling with a single laser-cooled Be+.

  9. Three-Rod Linear Ion Traps

    NASA Technical Reports Server (NTRS)

    Janik, Gary R.; Prestage, John D.; Maleki, Lutfollah

    1993-01-01

    Three-parallel-rod electrode structures proposed for use in linear ion traps and possibly for electrostatic levitation of macroscopic particles. Provides wider viewing angle because they confine ions in regions outside rod-electrode structures.

  10. Improved Linear-Ion-Trap Frequency Standard

    NASA Technical Reports Server (NTRS)

    Prestage, John D.

    1995-01-01

    Improved design concept for linear-ion-trap (LIT) frequency-standard apparatus proposed. Apparatus contains lengthened linear ion trap, and ions processed alternately in two regions: ions prepared in upper region of trap, then transported to lower region for exposure to microwave radiation, then returned to upper region for optical interrogation. Improved design intended to increase long-term frequency stability of apparatus while reducing size, mass, and cost.

  11. Coulomb crystallization of highly charged ions

    NASA Astrophysics Data System (ADS)

    Schmöger, L.; Versolato, O. O.; Schwarz, M.; Kohnen, M.; Windberger, A.; Piest, B.; Feuchtenbeiner, S.; Pedregosa-Gutierrez, J.; Leopold, T.; Micke, P.; Hansen, A. K.; Baumann, T. M.; Drewsen, M.; Ullrich, J.; Schmidt, P. O.; López-Urrutia, J. R. Crespo

    2015-03-01

    Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically 40Ar13+) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be+ ions. We also demonstrate cooling of a single Ar13+ ion by a single Be+ ion—the prerequisite for quantum logic spectroscopy with a potential 10-19 accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.

  12. Exploring structural phase transitions of ion crystals

    PubMed Central

    Yan, L. L.; Wan, W.; Chen, L.; Zhou, F.; Gong, S. J.; Tong, X.; Feng, M.

    2016-01-01

    Phase transitions have been a research focus in many-body physics over past decades. Cold ions, under strong Coulomb repulsion, provide a repealing paradigm of exploring phase transitions in stable confinement by electromagnetic field. We demonstrate various conformations of up to sixteen laser-cooled 40Ca+ ion crystals in a home-built surface-electrode trap, where besides the usually mentioned structural phase transition from the linear to the zigzag, two additional phase transitions to more complicated two-dimensional configurations are identified. The experimental observation agrees well with the numerical simulation. Heating due to micromotion of the ions is analysed by comparison of the numerical simulation with the experimental observation. Our investigation implies very rich and complicated many-body behaviour in the trapped-ion systems and provides effective mechanism for further exploring quantum phase transitions and quantum information processing with ultracold trapped ions. PMID:26865229

  13. Atomic Clock Based On Linear Ion Trap

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Dick, G. John

    1992-01-01

    Highly stable atomic clock based on excitation and measurement of hyperfine transition in 199Hg+ ions confined in linear quadrupole trap by radio-frequency and static electric fields. Configuration increases stability of clock by enabling use of enough ions to obtain adequate signal while reducing non-thermal component of motion of ions in trapping field, reducing second-order Doppler shift of hyperfine transition. Features described in NPO-17758 "Linear Ion Trap for Atomic Clock." Frequency standard based on hyperfine transition described in NPO-17456, "Trapped-Mercury-Ion Frequency Standard."

  14. Microfabricated linear Paul-Straubel ion trap

    DOEpatents

    Mangan, Michael A.; Blain, Matthew G.; Tigges, Chris P.; Linker, Kevin L.

    2011-04-19

    An array of microfabricated linear Paul-Straubel ion traps can be used for mass spectrometric applications. Each ion trap comprises two parallel inner RF electrodes and two parallel outer DC control electrodes symmetric about a central trap axis and suspended over an opening in a substrate. Neighboring ion traps in the array can share a common outer DC control electrode. The ions confined transversely by an RF quadrupole electric field potential well on the ion trap axis. The array can trap a wide array of ions.

  15. Extended linear ion trap frequency standard apparatus

    NASA Technical Reports Server (NTRS)

    Prestage, John D. (Inventor)

    1995-01-01

    A linear ion trap for frequency standard applications is provided with a plurality of trapping rods equally spaced and applied quadruple rf voltages for radial confinement of atomic ions and biased level pins at each end for axial confinement of the ions. The trapping rods are divided into two linear ion trap regions by a gap in each rod in a common radial plane to provide dc discontinuity, thus dc isolating one region from the other. A first region for ion-loading and preparation fluorescence is biased with a dc voltage to transport ions into a second region for resonance frequency comparison with a local oscillator derived frequency while the second region is held at zero voltage. The dc bias voltage of the regions is reversed for transporting the ions back into the first region for fluorescence measurement. The dual mode cycle is repeated continuously for comparison and feedback control of the local oscillator derived frequency. Only the second region requires magnetic shielding for the resonance function which is sensitive to any ambient magnetic fields.

  16. An improved linear ion trap physics package

    NASA Technical Reports Server (NTRS)

    Prestage, J. D.

    1993-01-01

    This article describes an improvement in the architecture of the physics package used in the Linear Ion Trap (LIT)-based frequency standard recently developed at JPL. This new design is based on the observation that ions can be moved along the axis of an LIT by applied dc voltages. The state selection and interrogation region can be separated from the more critical microwave resonance region where the multiplied local oscillator signal is compared with the stable atomic transition. This separation relaxes many of the design constraints of the present units. Improvements include increased frequency stability and a substantial reduction in size, mass, and cost of the final frequency standard.

  17. Miniaturized Linear Wire Ion Trap Mass Analyzer.

    PubMed

    Wu, Qinghao; Li, Ailin; Tian, Yuan; Zare, Richard N; Austin, Daniel E

    2016-08-01

    We report a linear ion trap (LIT) in which the electric field is formed by fine wires held under tension and accurately positioned using holes drilled in two end plates made of plastic. The coordinates of the hole positions were optimized in simulation. The stability diagram and mass spectra using boundary ejection were compared between simulation and experiment and good agreement was found. The mass spectra from experiments show peak widths (fwhm) in units of mass-to-charge of around 0.38 Th using a scan rate of 3830 Th/s. The limits of detection are 137 ppbv and 401 ppbv for benzene and toluene, respectively. Different sizes of the wire ion trap can be easily fabricated by drilling holes in scaled positions. Other distinguishing features, such as high ion and photon transmission, low capacitance, high tolerance to mechanical and assembly error, and low weight, are discussed. PMID:27373557

  18. Linear ion trap based atomic frequency standard

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Dick, G. J.; Maleki, Lute

    1991-01-01

    In order to develop a trapped ion-based fieldable frequency standard with stability 1 x 10 to the -13th/sq rt tau for averaging times tau greater than 10,000 s, a hybrid RF/DC linear ion trap was developed which permits storage of large numbers of ions with reduced susceptibility to the second-order Doppler effect caused by the RF confining fields. The authors have confined Hg-199(+) ions in this trap and have measured very high Q transitions with good SNRs. In preliminary measurements they obtained stabilities of 1.6 x 10 to the -13th/sq rt tau (tau between 50 and 800 s) with a 160-mHz wide atomic resonance linewidth and a signal-to-noise ratio of 40 for each measurement cycle. Atomic resonance lines as narrow as 30 mHz on the 40.5-GHz clock transition have been measured with no appreciable reduction in the ion signal. A stability of 7 x 10 to the -14th/sq rt tau is made possible by the signal-to-noise and line Q of this measured transition. Analysis of fundamental sources of frequency instability indicates that a long-term stability of 2 x 10 to the -16th is feasible for this device with existing technology for tau = 10 to the 6th s or more.

  19. Doppler Sideband Spectra for Ions in a Linear Trap

    NASA Technical Reports Server (NTRS)

    Prestage, J. D.; Tjoelker, R. L.; Dick, G. J.; Maleki, L.

    1993-01-01

    We describe a spectroscopic measurement of the temperature and linear density of HG+ ions held in a linear ion trap (LIT). The inferred temperature and number result from analysis of sidebands on the 40.5 GHz resonance line.

  20. Simple analytic potentials for linear ion traps

    NASA Technical Reports Server (NTRS)

    Janik, G. R.; Prestage, J. D.; Maleki, L.

    1989-01-01

    A simple analytical model was developed for the electric and ponderomotive (trapping) potentials in linear ion traps. This model was used to calculate the required voltage drive to a mercury trap, and the result compares well with experiments. The model gives a detailed picture of the geometric shape of the trapping potenital and allows an accurate calculation of the well depth. The simplicity of the model allowed an investigation of related, more exotic trap designs which may have advantages in light-collection efficiency.

  1. Simple analytic potentials for linear ion traps

    NASA Technical Reports Server (NTRS)

    Janik, G. R.; Prestage, J. D.; Maleki, L.

    1990-01-01

    A simple analytical model was developed for the electric and ponderomotive (trapping) potentials in linear ion traps. This model was used to calculate the required voltage drive to a mercury trap, and the result compares well with experiments. The model gives a detailed picture of the geometric shape of the trapping potential and allows an accurate calculation of the well depth. The simplicity of the model allowed an investigation of related, more exotic trap designs which may have advantages in light-collection efficiency.

  2. Theoretical studies for novel non-linear optical crystals

    NASA Astrophysics Data System (ADS)

    Wu, Kechen; Chen, Chuangtian

    1996-09-01

    To fulfil the "molecular engineering" of non-linear optical crystals, two theoretical models suitable respectively for the studies of the absorption edge and birefringence of a non-linear optical crystal have been set up. Molecular quantum chemical methods have been adopted in the systematic calculations of some typical crystals. DV-SCM-X α methods have been used to calculate the absorption edge on the UV side of BBO, LBO, KB5, KDP, Na 2SbF 5, Ba 2TiSi 2O 8, iodate and NaNO 2 crystals. Ab initio methods have been adopted to study the birefringence of NaNO 2, BBO, LiIO 3 and urea crystals. All the theoretical results agreed well with the experimental values. The relationship between structure and properties has been discussed. The results will be helpful to the search for novel non-linear optical crystals.

  3. Quasiequilibrium Characterization of Mixed-Ion Coulomb Crystals

    NASA Astrophysics Data System (ADS)

    Okada, Kunihiro; Ichikawa, Masanari; Wada, Michiharu; Schuessler, Hans A.

    2015-11-01

    We demonstrate the application of reliable methods to determine both the average micromotion energies and the number of sympathetically cooled ions (SCIs) embedded in mixed-ion Coulomb crystals in a linear Paul trap. The number of the SCIs and the micromotion energies for the observed mixed-ion crystals are determined by comparing experimentally obtained images with molecular-dynamics simulations, where the kinetic energies of SCIs trapped in rf fields are averaged in cold elastic collisions between the laser-cooled ions and virtual very light atoms. This combined method quickly achieves the quasiequilibrium state of large mixed Coulomb crystals with over 103 ions, regardless of the initial conditions, and shows that the previously used pseudopotential-based adiabatic approximations should be replaced by such molecular-dynamics simulations. In addition, a pattern-matching recognition procedure is introduced which objectively ascertains the number of ions. We also apply the presented characterization method to determine the reaction-rate constant between slow acetonitrile molecules and sympathetically cooled Ne+ ions at a translational temperature lower than 10 K.

  4. F 3 - molecular ions in fluoride crystals

    NASA Astrophysics Data System (ADS)

    Radzhabov, E. A.

    2016-02-01

    The UV absorption spectra of F 3 - molecular ions in LaF3, SrF2, CaF2, and BaF2 crystals doped with rare-earth elements are studied. Comparison of radiation-colored and additively colored crystals reveals the absorption bands of F 3 - hole centers in the region near 6 eV. Nonempirical calculations of optical transitions agree well with experimental results.

  5. Crystal-amorphous-silicon interface kinetics under ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Priolo, F.; La Ferla, A.; Spinella, C.; Rimini, E.; Campisano, S. U.; Ferla, G.

    1990-01-01

    Our recent work on ion-beam-assisted epitaxial growth of amorphous Si layers on single crystal substrates is reviewed. The crystallization was induced by a 600 keV Kr2+ beam at a dose rate of 1×1012/cm2 · s. During irradiations the samples were mounted on a resistively heated copper block whose temperature was maintained constant in the range 250-450°C. The planar motion of the crystal-amorphous interface was monitored in situ by dynamic reflectivity measurements. This technique allows the ion-induced growth rate to be measured with a very high precision. We have observed that this growth rate scales linearly with the energy deposited into elastic collisions at the crystal-amorphous interface by the impinging ions. Moreover, the rate shows an Arrhenius temperature dependence with a well defined activation energy of 0.32±0.05 eV. The dependence of this process on substrate orientation and on impurities either dissolved in the amorphous layer or present at very high concentration at the crystal-amorphous interface is also discussed.

  6. Crystal-amorphous-silicon interface kinetics under ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Priolo, F.; La Ferla, A.; Spinella, C.; Rimini, E.; Campisano, S. U.; Ferla, G.

    1989-11-01

    Our recent work on ion-beam-assisted epitaxial growth of amorphous Si layers on single crystal substrates is reviewed. The crystallization was induced by a 600 keV Kr 2+ beam at a dose rate of 1×10 12/cm 2 · s. During irradiations the samples were mounted on a resistively heated copper block whose temperature was maintained constant in the range 250-450°C. The planar motion of the crystal-amorphous interface was monitored in situ by dynamic reflectivity measurements. This technique allows the ion-induced growth rate to be measured with a very high precision. We have observed that this growth rate scales linearly with the energy deposited into elastic collisions at the crystal-amorphous interface by the impinging ions. Moreover, the rate shows an Arrhenius temperature dependence with a well defined activation energy of 0.32±0.05 eV. The dependence of this process on substrate orientation and on impurities either dissolved in the amorphous layer or present at very high concentration at the crystal-amorphous interface is also discussed.

  7. Birefringence of the antiferromagnetic crystals linear in a magnetic field

    NASA Astrophysics Data System (ADS)

    Eremenko, V. V.; Kharchenko, N. F.; Beliy, L. I.; Tutakina, O. P.

    1980-01-01

    The new linear magneto-optical effect-birefringence-of a linear polarized light which is directly proportional to the magnetic field strength has been observed. This effect is permitted in crystals which allow piezo-magnetic properties. One was studied in antiferromagnet CoF 2 and CoCO 3 for the longitudinal geometry of an experiment.

  8. Coulomb crystal mass spectrometry in a digital ion trap

    NASA Astrophysics Data System (ADS)

    Deb, Nabanita; Pollum, Laura L.; Smith, Alexander D.; Keller, Matthias; Rennick, Christopher J.; Heazlewood, Brianna R.; Softley, Timothy P.

    2015-03-01

    We present a mass spectrometric technique for identifying the masses and relative abundances of Coulomb-crystallized ions held in a linear Paul trap. A digital radio-frequency wave form is employed to generate the trapping potential, as this can be cleanly switched off, and static dipolar fields are subsequently applied to the trap electrodes for ion ejection. Close to 100% detection efficiency is demonstrated for Ca+ and CaF+ ions from bicomponent Ca+-CaF+ Coulomb crystals prepared by the reaction of Ca+ with CH3F . A quantitative linear relationship is observed between ion number and the corresponding integrated time-of-flight (TOF) peak, independent of the ionic species. The technique is applicable to a diverse range of multicomponent Coulomb crystals—demonstrated here for Ca+-NH 3+ -NH 4+ and Ca+-CaOH +-CaOD + crystals—and will facilitate the measurement of ion-molecule reaction rates and branching ratios in complicated reaction systems.

  9. Progress in linear optics, non-linear optics and surface alignment of liquid crystals

    SciTech Connect

    Ong, H.L.; Meyer, R.B.; Hurd, A.J.; Karn, A.J.; Arakelian, S.M.; Shen, Y.R.; Sanda, P.N.; Dove, D.B.; Jansen, S.A.; Hoffmann, R.

    1989-01-01

    We first discuss the progress in linear optics, in particular, the formulation and application of geometrical-optics approximation and its generalization. We then discuss the progress in non-linear optics, in particular, the enhancement of a first-order Freedericksz transition and intrinsic optical bistability in homeotropic and parallel oriented nematic liquid crystal cells. Finally, we discuss the liquid crystal alignment and surface effects on field-induced Freedericksz transition. 50 refs.

  10. Non-linear optical crystal vibration sensing device

    DOEpatents

    Kalibjian, R.

    1994-08-09

    A non-linear optical crystal vibration sensing device including a photorefractive crystal and a laser is disclosed. The laser produces a coherent light beam which is split by a beam splitter into a first laser beam and a second laser beam. After passing through the crystal the first laser beam is counter-propagated back upon itself by a retro-mirror, creating a third laser beam. The laser beams are modulated, due to the mixing effect within the crystal by vibration of the crystal. In the third laser beam, modulation is stable and such modulation is converted by a photodetector into a usable electrical output, intensity modulated in accordance with vibration applied to the crystal. 3 figs.

  11. Non-linear optical crystal vibration sensing device

    DOEpatents

    Kalibjian, Ralph

    1994-01-11

    A non-linear optical crystal vibration sensing device (10) including a photorefractive crystal (26) and a laser (12). The laser (12 ) produces a coherent light beam (14) which is split by a beam splitter (18) into a first laser beam (20) and a second laser beam (22). After passing through the crystal (26) the first laser beam (20) is counter-propagated back upon itself by a retro-mirror (32), creating a third laser beam (30). The laser beams (20, 22, 30) are modulated, due to the mixing effect within the crystal (26) by vibration of the crystal (30). In the third laser beam (30), modulation is stable and such modulation is converted by a photodetector (34) into a usable electrical output, intensity modulated in accordance with vibration applied to the crystal (26).

  12. Design Optimization for Anharmonic Linear Surface-Electrode Ion Trap

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Chen, Shu-Ming; Chen, Ping-Xing; Wu, Wei

    2014-11-01

    An accurate and rapid method is proposed to optimize anharmonic linear surface-electrode ion trap design. Based on the method, we analyze the impact of the architectural parameters, including the width, number, and applied voltage of prerequisite active electrodes, on the number and spacing of trapped ions. Sets of optimal anharmonic trap design are given. Then the optimal designs are verified by using an ant colony optimization algorithm. The results show that the maximum ion position errors and maximum ion spacing errors are less than 1 μm up to 80. The mean of the maximum errors is nearly linear with respect to the number of trapped ions.

  13. Linear ion source with magnetron hollow cathode discharge

    SciTech Connect

    Tang, D.L.; Pu, S.H.; Wang, L.S.; Qiu, X.M.; Chu, Paul K.

    2005-11-15

    A linear ion source with magnetron hollow cathode discharge is described in this paper. The linear ion source is based on an anode layer thruster with closed-drift electrons that move in a closed path in the ExB fields. An open slit configuration is designed at the end of the ion source for the extraction of the linear ion beam produced by the magnetron hollow cathode discharge. The special configurations enable uninterrupted and expanded operation with oxygen as well as other reactive gases because of the absence of an electron source in the ion source. The ion current density and uniformity were experimentally evaluated. Using the ion source, surface modification was conducted on polyethylene terephthalate polymer films to improve the adhesion strength with ZnS coatings.

  14. Control of the conformations of ion Coulomb crystals in a Penning trap

    PubMed Central

    Mavadia, Sandeep; Goodwin, Joseph F.; Stutter, Graham; Bharadia, Shailen; Crick, Daniel R.; Segal, Daniel M.; Thompson, Richard C.

    2013-01-01

    Laser-cooled atomic ions form ordered structures in radiofrequency ion traps and in Penning traps. Here we demonstrate in a Penning trap the creation and manipulation of a wide variety of ion Coulomb crystals formed from small numbers of ions. The configuration can be changed from a linear string, through intermediate geometries, to a planar structure. The transition from a linear string to a zigzag geometry is observed for the first time in a Penning trap. The conformations of the crystals are set by the applied trap potential and the laser parameters, and agree with simulations. These simulations indicate that the rotation frequency of a small crystal is mainly determined by the laser parameters, independent of the number of ions and the axial confinement strength. This system has potential applications for quantum simulation, quantum information processing and tests of fundamental physics models from quantum field theory to cosmology. PMID:24096901

  15. Linear electric field time-of-flight ion mass spectrometer

    DOEpatents

    Funsten, Herbert O.; Feldman, William C.

    2008-06-10

    A linear electric field ion mass spectrometer having an evacuated enclosure with means for generating a linear electric field located in the evacuated enclosure and means for injecting a sample material into the linear electric field. A source of pulsed ionizing radiation injects ionizing radiation into the linear electric field to ionize atoms or molecules of the sample material, and timing means determine the time elapsed between ionization of atoms or molecules and arrival of an ion out of the ionized atoms or molecules at a predetermined position.

  16. Ion Coulomb Crystals and Their Applications

    NASA Astrophysics Data System (ADS)

    Drewsen, Michael

    The following text will give a brief introduction to the physics of the spatially ordered structures, so-called Coulomb crystals, that appear when confined ions are cooled to sufficiently low temperatures. It will as well briefly comment on the very diverse scientific applications of such crystals, which have emerged in the past two decades. While this document lacks figures and many specific references, it is the hope, not the text will stimulate the reader to dig deeper into one or more of the discussed subjects, and inspire her/him to think about new potential applications. A fully referenced journal article of essentially the same text can be found in Physica B 460, 105 (2015) [1].

  17. Differentially pumped dual linear quadrupole ion trap mass spectrometer

    SciTech Connect

    Owen, Benjamin C.; Kenttamaa, Hilkka I.

    2015-10-20

    The present disclosure provides a new tandem mass spectrometer and methods of using the same for analyzing charged particles. The differentially pumped dual linear quadrupole ion trap mass spectrometer of the present disclose includes a combination of two linear quadrupole (LQIT) mass spectrometers with differentially pumped vacuum chambers.

  18. All-linear time reversal by a dynamic artificial crystal

    PubMed Central

    Chumak, Andrii V.; Tiberkevich, Vasil S.; Karenowska, Alexy D.; Serga, Alexander A.; Gregg, John F.; Slavin, Andrei N.; Hillebrands, Burkard

    2010-01-01

    The time reversal of pulsed signals or propagating wave packets has long been recognized to have profound scientific and technological significance. Until now, all experimentally verified time-reversal mechanisms have been reliant upon nonlinear phenomena such as four-wave mixing. In this paper, we report the experimental realization of all-linear time reversal. The time-reversal mechanism we propose is based on the dynamic control of an artificial crystal structure, and is demonstrated in a spin-wave system using a dynamic magnonic crystal. The crystal is switched from an homogeneous state to one in which its properties vary with spatial period a, while a propagating wave packet is inside. As a result, a linear coupling between wave components with wave vectors k≈π/a and k′=k−2ππ/a≈−π/a is produced, which leads to spectral inversion, and thus to the formation of a time-reversed wave packet. The reversal mechanism is entirely general and so applicable to artificial crystal systems of any physical nature. PMID:21266991

  19. Electrochemical growth of linear conducting crystals in microgravity

    NASA Technical Reports Server (NTRS)

    Cronise, Raymond J., IV

    1988-01-01

    Much attention has been given to the synthesis of linear conducting materials. These inorganic, organic, and polymeric materials have some very interesting electrical and optical properties, including low temperature superconductivity. Because of the anisotropic nature of these compounds, impurities and defects strongly influences the unique physical properties of such crystals. Investigations have demonstrated that electrochemical growth has provided the most reproducible and purest crystals. Space, specifically microgravity, eliminates phenomena such as buoyancy driven convection, and could permit formation of crystals many times purer than the ones grown to date. Several different linear conductors were flown on Get Away Special G-007 on board the Space Shuttle Columbia, STS 61-C, the first of a series of Project Explorer payloads. These compounds were grown by electrochemical methods, and the growth was monitored by photographs taken throughout the mission. Due to some thermal problems, no crystals of appreciable size were grown. The experimental results will be incorporated into improvements for the next 2 missions of Project Explorer. The results and conclusions of the first mission are discussed.

  20. Reducing Space Charge Effects in a Linear Ion Trap by Rhombic Ion Excitation and Ejection.

    PubMed

    Zhang, Xiaohua; Wang, Yuzhuo; Hu, Lili; Guo, Dan; Fang, Xiang; Zhou, Mingfei; Xu, Wei

    2016-07-01

    Space charge effects play important roles in ion trap operations, which typically limit the ion trapping capacity, dynamic range, mass accuracy, and resolving power of a quadrupole ion trap. In this study, a rhombic ion excitation and ejection method was proposed to minimize space charge effects in a linear ion trap. Instead of applying a single dipolar AC excitation signal, two dipolar AC excitation signals with the same frequency and amplitude but 90° phase difference were applied in the x- and y-directions of the linear ion trap, respectively. As a result, mass selective excited ions would circle around the ion cloud located at the center of the ion trap, rather than go through the ion cloud. In this work, excited ions were then axially ejected and detected, but this rhombic ion excitation method could also be applied to linear ion traps with ion radial ejection capabilities. Experiments show that space charge induced mass resolution degradation and mass shift could be alleviated with this method. For the experimental conditions in this work, space charge induced mass shift could be decreased by ~50%, and the mass resolving power could be improved by ~2 times at the same time. Graphical Abstract ᅟ. PMID:27080008

  1. Reducing Space Charge Effects in a Linear Ion Trap by Rhombic Ion Excitation and Ejection

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaohua; Wang, Yuzhuo; Hu, Lili; Guo, Dan; Fang, Xiang; Zhou, Mingfei; Xu, Wei

    2016-07-01

    Space charge effects play important roles in ion trap operations, which typically limit the ion trapping capacity, dynamic range, mass accuracy, and resolving power of a quadrupole ion trap. In this study, a rhombic ion excitation and ejection method was proposed to minimize space charge effects in a linear ion trap. Instead of applying a single dipolar AC excitation signal, two dipolar AC excitation signals with the same frequency and amplitude but 90° phase difference were applied in the x- and y-directions of the linear ion trap, respectively. As a result, mass selective excited ions would circle around the ion cloud located at the center of the ion trap, rather than go through the ion cloud. In this work, excited ions were then axially ejected and detected, but this rhombic ion excitation method could also be applied to linear ion traps with ion radial ejection capabilities. Experiments show that space charge induced mass resolution degradation and mass shift could be alleviated with this method. For the experimental conditions in this work, space charge induced mass shift could be decreased by ~50%, and the mass resolving power could be improved by ~2 times at the same time.

  2. Locations of Halide Ions in Tetragonal Lysozyme Crystals

    NASA Technical Reports Server (NTRS)

    Lim, Kap; Adimurthy, Ganapathi; Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

    1998-01-01

    Anions play an important role in the crystallization of lysozyme, and are known to bind to the crystalline protein. Previous studies employing X-ray crystallography had found one chloride ion binding site in the tetragonal crystal form of the protein and four nitrate ion binding sites in the monoclinic form. Studies using other approaches have reported more chloride ion binding sites, but their locations were not known. Knowing the precise location of these anions is also useful in determining the correct electrostatic fields surrounding the protein. In the first part of this study the anion positions in the tetragonal form were determined from the difference Fourier map obtained from the lysozyme crystals grown in bromide and chloride solutions under identical conditions. The anion locations were then obtained from standard crystallographic methods and five possible anion binding sites were found in this manner. The sole chloride ion binding site found in previous studies was confirmed. The remaining four sites were new ones for tetragonal lysozyme crystals. However, three of these new sites and the previously found one corresponded to the four unique binding sites found for nitrate ions in monoclinic crystals. This suggests that most of the anion binding sites in lysozyme remain unchanged, even when different anions and different crystal forms of lysozyme are employed. It is unlikely that there are many more anions in the tetragonal lysozyme crystal structure. Assuming osmotic equilibrium it can be shown that there are at most three more anions in the crystal channels. Some of the new anion binding sites found in this study were, as expected, in pockets containing basic residues. However, some of them were near neutral, but polar, residues. Thus, the study also showed the importance of uncharged, but polar groups, on the protein surface in determining its electrostatic field. This was important for the second part of this study where the electrostatic field

  3. Stabilizing blue phase liquid crystals with linearly polarized UV light

    NASA Astrophysics Data System (ADS)

    Xu, Daming; Yuan, Jiamin; Schadt, Martin; Yan, Jing; Wu, Shin-Tson

    2015-03-01

    Polymer-stabilized blue-phase liquid crystal (PS-BPLC) has become an increasingly important technology trend for information display and photonic applications. BPLC exhibits several attractive features, such as reasonably wide temperature range, submillisecond gray-to-gray response time, no need for alignment layer, optically isotropic voltageoff state, and large cell gap tolerance when an in-plane switching (IPS) cell is employed. However, some bottlenecks such as high operation voltage, relatively low transmittance, and noticeable hysteresis and prolonged response time at high field region for IPS mode, still remain to be overcome before widespread application of BPLC can be realized. To reduce operation voltage, both new BPLC materials and new device structures have been investigated. In this paper, we demonstrate the stabilization a photopolymer-embedded blue phase liquid crystal precursor using a linearly polarized UV light for first time. When the UV polarization axis is perpendicular to the stripe electrodes of an IPS cell, anisotropic polymer networks are formed through the linear photo-polymerization process and the electrostriction effect is suppressed. As a result, the measured hysteresis is dramatically reduced from 6.95% to 0.36% and the response time shortened by ~2X compared to unpolarized UV exposure. To induce larger anisotropy in polymer networks for mitigating the electrostriction effect, high-intensity linearly polarized UV exposure is preferred. It is foreseeable this method will guide future BPLC device and material development as well as manufacturing process. The dawn of BPLCD is near.

  4. Spiroborate Ions for Crystallization and Resolution

    NASA Astrophysics Data System (ADS)

    Wong, Lawrence Wan Yin

    Spiroborate anions are boron compounds with two oxygen based chelating ligands which offer useful prospects for crystallization and chiral resolution. In particular the application and the rationale of using chiral spiroborates with either B-based or ligand-based chirality as a simple, cheap and effective auxiliaries for resolution are studied. In Chapter 2 the scope and limitations of spiroborate formation and crystallization are explored through different classes by investigating their structures and properties. Structures of five different classes are described including spiroborates derived from various diols, catechols, a-hydroxy acids, hydroxybenzoic acids and hydroxyl oximes. The crystallizing abilities are demonstrated with successful isolation of stable product using differing cations. Both limitations and difficulties in each system are also discussed. In chapter 3 chiral spiroborate anions bora-bis-mandelate [B(Man) 2] anions are introduced as highly effective auxiliary for resolution of various racemic chiral cations. The scope of their application is well exemplified by, though not limited to, three disparate examples; the pharmaceutically important natural alkaloid tetrahydropalmatine (THP) which forms a mono-cation, the small 1,2-diaminopropane (1,2-dap) which forms a dication and the metal-organic complex [Co(phen)3]3+. The resulting salts with [B(Man)2] are 1:1, 1:2 and 1:3 stoichiometry. The resolutions may be either by a facile one-pot solvothermal procedure or via counter-ion exchange in metathesis crystallizations using a pre-prepared salt such as Na[B(Man) 2]. High ee of > 90 % have been achieved in all three systems and confirmed by chiral chromatography and/or Circular Dichroism spectroscopy. In Chapter 4 the investigation of spiroborate diastereomeric ion pairs using chiral [B(Man)2] anions and chiral aminoalcohols were undertaken to better understand the structural issues of chiral resolution and predict the resolution result. Three other

  5. Interaction of the excited ions-activators in laser crystals

    NASA Astrophysics Data System (ADS)

    Zubenko, D. A.; Noginov, M. A.; Ostroumov, Vasiliy G.; Semenkov, S. G.; Smirnov, V. A.; Shcherbakov, Ivan A.

    1992-11-01

    Processes of interaction of excited ions are investigated in several laser crystals: Er-Er -- in YSGG:Cr, Er and GSAG:Cr,Er crystals; Ho-Ho -- in YSGG:Cr, Ho crystals; Tm-Tm -- in YSGG:Cr,Tm and YAG:Cr,Tm crystals; Tm-Ho -- in YSGG:Cr, Tm, Ho and YSAG:Cr, Tm, Ho crystals; Cr-Cr -- in 11 of different laser crystals (ruby, YAG, GSGG, YSGG, LICAF, et al.); Cr-TR (Er, Ho, Tb, Tm, Nd, -- TR) in YAG, YSGG, GSGG, GSAG crystals.

  6. Linear analysis of ion cyclotron interaction in a multicomponent plasma

    NASA Technical Reports Server (NTRS)

    Gendrin, R.; Ashour-Abdalla, M.; Omura, Y.; Quest, K.

    1984-01-01

    The mechanism by which hot anisotropic protons generate electromagnetic ion cyclotron waves in a plasma containing cold H(+) and He(+) ions is quantitatively studied. Linear growth rates (both temporal and spatial) are computed for different plasma parameters: concentration, temperature,and anisotropy of cold He(+) ions and of hot protons. It is shown that: (1) for parameters typical of the geostationary altitude the maximum growth rates are not drastically changed when a small proportion (about 1 to 20 percent) of cold He(+) ions is present; (2) because of the important cyclotron absorption by thermal He(+) ions in the vicinity of the He(+) gyrofrequency, waves which could resonate with the bulk of the He(+) distribution cannot be generated. Therefore quasi-linear effects, in a homogeneous medium at least, cannot be responsible for the heating of He(+) ions which is often observed in conjunction with ion cyclotron waves. The variation of growth rate versus wave number is also studied for its importance in selecting suitable parameters in numerical simulation experiments.

  7. A simulation study of linear RF ion guides for AMS

    NASA Astrophysics Data System (ADS)

    Zhao, X.-L.; Litherland, A. E.

    2015-02-01

    The use of radiofrequency multipoles and particularly the radiofrequency quadrupole (RFQ) controlled gas cell to facilitate on-line isobar separations for Accelerator Mass Spectrometry (AMS) is being explored experimentally and theoretically in a preliminary way at present. These new methods have the potential to extend greatly the analytical scope of AMS. However, there are many technical challenges to adapt an RF gas cell isobar separating device and still maintain stable and high transmission for routine AMS using the high current Cs+ sputter ion sources developed for nuclear physics and adapted to the detection of rare radioactive isotopes for AMS. An overview of linear RF ion guide properties is therefore needed to assist in the conceptualization of their efficient additions into AMS. In this work the intrinsic properties of linear RF ion guides, which are relevant to the generation of the RF induced ion energy distributions and for the evaluation of the ion transmissions in vacuum, are systematically studied using SIMION 8.1. These properties are compared among radiofrequency quadrupole, hexapole and octupole ion guides, so that their usefulness for AMS applications can be evaluated and compared. By simulation it is found that to prepare a typical RF captured AMS ion beam to within a safe range of ion energies prior to the onset of gas interactions, a higher multipole is more suitable for the first RF field receptor, while a quadrupole operated with q2 ∼ 0.5 is more suited as the final ion guide for concentrating the energy-cooled ions near axis.

  8. Theoretical Study of Dual-Direction Dipolar Excitation of Ions in Linear Ion Traps

    NASA Astrophysics Data System (ADS)

    Dang, Qiankun; Xu, Fuxing; Wang, Liang; Huang, Xiaohua; Dai, Xinhua; Fang, Xiang; Wang, Rizhi; Ding, Chuan-Fan

    2016-04-01

    The ion enhanced activation and collision-induced dissociation (CID) by simultaneous dipolar excitation of ions in the two radial directions of linear ion trap (LIT) have been recently developed and tested by experiment. In this work, its detailed properties were further studied by theoretical simulation. The effects of some experimental parameters such as the buffer gas pressure, the dipolar excitation signal phases, power amplitudes, and frequencies on the ion trajectory and energy were carefully investigated. The results show that the ion activation energy can be significantly increased by dual-direction excitation using two identical dipolar excitation signals because of the addition of an excitation dimension and the fact that the ion motion radius related to ion kinetic energy can be greater than the field radius. The effects of higher-order field components, such as dodecapole field on the performance of this method are also revealed. They mainly cause ion motion frequency shift as ion motion amplitude increases. Because of the frequency shift, there are different optimized excitation frequencies in different LITs. At the optimized frequency, ion average energy is improved significantly with relatively few ions lost. The results show that this method can be used in different kinds of LITs such as LIT with 4-fold symmetric stretch, linear quadrupole ion trap, and standard hyperbolic LIT, which can significantly increase the ion activation energy and CID efficiency, compared with the conventional method.

  9. Theoretical Study of Dual-Direction Dipolar Excitation of Ions in Linear Ion Traps.

    PubMed

    Dang, Qiankun; Xu, Fuxing; Wang, Liang; Huang, Xiaohua; Dai, Xinhua; Fang, Xiang; Wang, Rizhi; Ding, Chuan-Fan

    2016-04-01

    The ion enhanced activation and collision-induced dissociation (CID) by simultaneous dipolar excitation of ions in the two radial directions of linear ion trap (LIT) have been recently developed and tested by experiment. In this work, its detailed properties were further studied by theoretical simulation. The effects of some experimental parameters such as the buffer gas pressure, the dipolar excitation signal phases, power amplitudes, and frequencies on the ion trajectory and energy were carefully investigated. The results show that the ion activation energy can be significantly increased by dual-direction excitation using two identical dipolar excitation signals because of the addition of an excitation dimension and the fact that the ion motion radius related to ion kinetic energy can be greater than the field radius. The effects of higher-order field components, such as dodecapole field on the performance of this method are also revealed. They mainly cause ion motion frequency shift as ion motion amplitude increases. Because of the frequency shift, there are different optimized excitation frequencies in different LITs. At the optimized frequency, ion average energy is improved significantly with relatively few ions lost. The results show that this method can be used in different kinds of LITs such as LIT with 4-fold symmetric stretch, linear quadrupole ion trap, and standard hyperbolic LIT, which can significantly increase the ion activation energy and CID efficiency, compared with the conventional method. Graphical Abstract ᅟ. PMID:26810433

  10. Theory and simulation of ion Coulomb crystal formation in a Penning trap

    NASA Astrophysics Data System (ADS)

    Asprusten, Martin; Worthington, Simon; Thompson, Richard C.

    2014-01-01

    Ion Coulomb crystals (ICCs) are formed by laser-cooled ions in both radio-frequency and Penning traps. In radio-frequency traps, the crystals are generally stationary. In Penning traps, ICCs always rotate. The frequency of rotation is often set by an applied rotating wall drive that forces the crystal to rotate at the same frequency as the drive. In the absence of any applied rotating or oscillating fields, ICCs in a Penning trap can be in stable equilibrium with a range of rotation frequencies. The density and shape of the crystal adjust with the rotation frequency to ensure that equilibrium is reached. Here, we show that the parameters of the radial laser-cooling beam determine the rotation frequency of a small crystal in a Penning trap when no driving fields are present. We demonstrate, using an approximate theoretical treatment and realistic simulations, that the crystal rotation frequency is independent of the number of ions and the trap parameters, so long as the crystal radius remains smaller than the cooling laser beam waist. As the rotation frequency increases, the crystal eventually becomes a linear string, at which point it is no longer able to adjust its density. Instead, a small amplitude vibration in the zigzag mode of oscillation manifests itself as a rotation of the crystal at a fixed frequency that depends only on the applied trap potential.

  11. Location of Bromide Ions in Tetragonal Lysozyme Crystals

    NASA Technical Reports Server (NTRS)

    Lim, Kap; Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

    1998-01-01

    Anions have been shown to play a dominant role in the crystallization of chicken egg white lysozyme from salt solutions. Previous studies employing X-ray crystallography had found one chloride ion binding site in the tetragonal crystal form of the protein and four nitrate ion binding sites in the monoclinic form. In this study the anion positions in the tetragonal form were determined from the difference Fourier map obtained from lysozyme crystal grown in bromide and chloride solutions. Five possible anion binding sites were found in this manner. Some of these sites were in pockets containing basic residues while others were near neutral, but polar, residues. The sole chloride ion binding site found in previous studies was confirmed, while four of these sites corresponded to four binding sites found for nitrate ions in monoclinic crystals. The study suggests that most of the anion binding sites in lysozyme remain unchanged, even when different anions and different crystal forms of lysozyme are employed.

  12. Ring-shaped Wigner crystals of trapped ions at the micronscale

    NASA Astrophysics Data System (ADS)

    Li, Haokun; Urban, Erik; Noel, Crystal; Chuang, Alexander; Xia, Yang; Hemmerling, Borge; Wang, Yuan; Zhang, Xiang; Haeffner, Hartmut

    Trapped ion crystals are ideal platforms to study many-body physics and quantum information processing, with both the internal electronic states and external motional degree-of-freedoms controllable at the single quantum level. In contrast to conventional, finite, linear chains of ions, a ring topology exhibiting periodic boundary conditions and rotational symmetry opens up a new directions to diverse topics. However, previous implementations of ion rings result in small aspect ratios (<0.07) of ion-electrode distance to ring diameter, making the rotational symmetry of the ion crystals prone to stray electric fields from imperfections of the trap electrodes, particularly evident at low temperatures. Here, using a new trap design with a 60-fold improvement of this aspect ratio, we demonstrate crystallization of 40Ca+ ions in a ring with rotational energy barriers comparable to the thermal energy of Doppler laser cooled ion crystals. When further reducing the rotational energy barriers, we observe delocalization of the ion rings. With this result, we enter a regime where quantum topological effects can be studied and novel quantum computation and simulation experiments can be implemented.

  13. A Linear RFQ Ion Trap for the Enriched Xenon Observatory

    SciTech Connect

    Flatt, B.; Green, M.; Wodin, J.; DeVoe, R.; Fierlinger, P.; Gratta, G.; LePort, F.; Montero Diez, M.; Neilson, R.; O'Sullivan, K.; Pocar, A.; Baussan, E.; Breidenbach, M.; Conley, R.; Fairbank Jr., W.; Farine, J.; Hall, K.; Hallman, D.; Hargrove, C.; Hauger, M.; Hodgson, J.; /Stanford U., Phys. Dept. /Neuchatel U. /SLAC /Colorado State U. /Laurentian U. /Carleton U. /Alabama U.

    2008-01-14

    The design, construction, and performance of a linear radio-frequency ion trap (RFQ) intended for use in the Enriched Xenon Observatory (EXO) are described. EXO aims to detect the neutrinoless double-beta decay of {sup 136}Xe to {sup 136}Ba. To suppress possible backgrounds EXO will complement the measurement of decay energy and, to some extent, topology of candidate events in a Xe filled detector with the identification of the daughter nucleus ({sup 136}Ba). The ion trap described here is capable of accepting, cooling, and confining individual Ba ions extracted from the site of the candidate double-beta decay event. A single trapped ion can then be identified, with a large signal-to-noise ratio, via laser spectroscopy.

  14. Crystal effects in the neutralization of He+ ions in the low energy ion scattering regime.

    PubMed

    Primetzhofer, D; Markin, S N; Juaristi, J I; Taglauer, E; Bauer, P

    2008-05-30

    Investigating possible crystal effects in ion scattering from elemental surfaces, measurements of the positive ion fraction P+ are reported for He+ ions scattered from single and polycrystalline Cu surfaces. In the Auger neutralization regime, the ion yield is determined by scattering from the outermost atomic layer. For Cu(110) P+ exceeds that for polycrystalline Cu by up to a factor of 2.5, thus exhibiting a strong crystal effect. It is much less pronounced at higher energies, i.e., in the reionization regime. However, there a completely different angular dependence of the ion yield is observed for poly- and single crystals, due to massive subsurface contributions in nonchanneling directions. PMID:18518602

  15. Frequency-scanning MALDI linear ion trap mass spectrometer for large biomolecular ion detection.

    PubMed

    Lu, I-Chung; Lin, Jung Lee; Lai, Szu-Hsueh; Chen, Chung-Hsuan

    2011-11-01

    This study presents the first report on the development of a matrix-assisted laser desorption ionization (MALDI) linear ion trap mass spectrometer for large biomolecular ion detection by frequency scan. We designed, installed, and tested this radio frequency (RF) scan linear ion trap mass spectrometer and its associated electronics to dramatically extend the mass region to be detected. The RF circuit can be adjusted from 300 to 10 kHz with a set of operation amplifiers. To trap the ions produced by MALDI, a high pressure of helium buffer gas was employed to quench extra kinetic energy of the heavy ions produced by MALDI. The successful detection of the singly charged secretory immunoglobulin A ions indicates that the detectable mass-to-charge ratio (m/z) of this system can reach ~385 000 or beyond. PMID:21932813

  16. Linear ion source with closed drift and extended acceleration region

    SciTech Connect

    Park, Dong-Hee; Kim, Ji-Hwan; Ermakov, Yury; Choi, Won-Kook

    2008-02-15

    Ion source with closed drift, which is caused by ExB field, and extended acceleration region is discussed. Though conventional circular-type closed drift ion source has advantages of high efficiency of gas ionization and low ion beam energy, there is a limitation in enlarging the beam size. Linear ion source with horse-track shape with 270 mm ceramic channel width is newly designed and tested. Inert gas (Ar) and reactive gas (O{sub 2}) are discharged. Discharge is ignited with voltage of 90 V. Discharge current is proportional to discharge voltage and increases up to 16.3 A in argon and 15.6 A in oxygen at discharge voltage of 320 V. Extracted ion beam current is also proportional to discharge voltage and is saturated after 280 V for both gases. It is measured up to 0.78 mA/cm{sup 2} in argon beam and 0.73 mA/cm{sup 2} in oxygen beam at a distance of 100 mm from the ion source. Argon ion beam shows better space uniformity than oxygen across the beam extraction region.

  17. Progress Report on the Improved Linear Ion Trap Physics Package

    NASA Technical Reports Server (NTRS)

    Prestage, John D.

    1995-01-01

    This article describes the first operational results from the extended linear ion trap frequency standard now being developed at JPL. This new design separates the state selection/interrogation region from the more critical microwave resonance region where the multiplied local oscillator (LO) signal is compared to the stable atomic transition. Hg+ ions have been trapped, shuttled back and forth between the resonance and state selection traps. In addition, microwave transitions between the Hg+ clock levels have been driven in the resonance trap and detected in the state selection trap.

  18. Beam Dynamics Design and Simulation in Ion Linear Accelerators (

    Energy Science and Technology Software Center (ESTSC)

    2006-08-01

    Orginally, the ray tracing code TRACK has been developed to fulfill the many special requirements for the Rare Isotope Accelerator Facility known as RIA. Since no available beam-dynamics code met all the necessary requirements, modifications to the code TRACK were introduced to allow end-to-end (from the ion souce to the production target) simulations of the RIA machine, TRACK is a general beam-dynamics code and can be applied for the design, commissioning and operation of modernmore » ion linear accelerators and beam transport systems.« less

  19. Beam Dynamics Design and Simulation in Ion Linear Accelerators (

    SciTech Connect

    Ostroumov, Peter N.; Asseev, Vladislav N.; Mustapha, and Brahim

    2006-08-01

    Orginally, the ray tracing code TRACK has been developed to fulfill the many special requirements for the Rare Isotope Accelerator Facility known as RIA. Since no available beam-dynamics code met all the necessary requirements, modifications to the code TRACK were introduced to allow end-to-end (from the ion souce to the production target) simulations of the RIA machine, TRACK is a general beam-dynamics code and can be applied for the design, commissioning and operation of modern ion linear accelerators and beam transport systems.

  20. Structure and dynamics of ion clusters in linear octupole traps: Phase diagrams, chirality, and melting mechanisms

    SciTech Connect

    Yurtsever, E.; Onal, E. D.; Calvo, F.

    2011-05-15

    The stable structures and melting dynamics of clusters of identical ions bound by linear octupole radiofrequency traps are theoretically investigated by global optimization methods and molecular dynamics simulations. By varying the cluster sizes in the range of 10-1000 ions and the extent of trap anisotropy by more than one order of magnitude, we find a broad variety of stable structures based on multiple rings at small sizes evolving into tubular geometries at large sizes. The binding energy of these clusters is well represented by two contributions arising from isotropic linear and octupolar traps. The structures generally exhibit strong size effects, and chiral arrangements spontaneously emerge in many crystals. Sufficiently large clusters form nested, coaxial tubes with different thermal stabilities. As in isotropic octupolar clusters, the inner tubes melt at temperatures that are lower than the overall melting point.

  1. Microsecond pulsed hydrogen/deuterium exchange of electrosprayed ubiquitin ions stored in a linear ion trap.

    PubMed

    Rajabi, Khadijeh

    2015-02-01

    A pulse of D2O vapour on the order of microseconds is allowed to react with the +6 to +9 charge states of ubiquitin confined in a linear ion trap (LIT). Two envelopes of peaks are detected for the ions of ubiquitin, corresponding to the ions that exchange more quickly and more slowly. The deuterium uptake of the protonated sites on ubiquitin ions accounts for the ion population with the fast exchange. The hydrogen/deuterium exchange (HDX) kinetics of ubiquitin ions trapped in the LIT for 200 ms showed comparable structural transitions to those trapped for 300 ms. When ions are trapped for longer, i.e. up to 2000 ms, mainly the slow exchanging ion population is detected. In all experiments the +7 ions exchange the most, suggesting a short distance between the surface protonated sites and nearby charged sites, and concomitantly high accessibility of surface protonated sites towards D2O. The +6 ions are more compact than the +7 ions but have one fewer protonated site, therefore fewer surface availabilities for D2O attack. The data suggest that the +6 ions keep most of their solution-phase contacts intact while the hydrophobic core is slightly interrupted in the +7 ions, possibly due to the exposure of charged His68 that is normally buried in the hydrophobic pocket. The +8 and +9 ions have more protonated sites but are less compact than the +7 ions because of Coulombic repulsion, resulting in a larger distance between the protonated sites and the basic sites. The data indicate that the HDX mechanism of ions with the slower exchange corresponding to the second envelope of peaks is primarily governed via a relay mechanism. The results suggest that the pulsed HDX MS method is sampling a population of ubiquitin ions with a similar backbone fold to the solution. PMID:25553956

  2. Automated measurement of permethylated serum N-glycans by MALDI-linear ion trap mass spectrometry.

    PubMed

    Guillard, Maïlys; Gloerich, Jolein; Wessels, Hans J C T; Morava, Eva; Wevers, Ron A; Lefeber, Dirk J

    2009-08-17

    The use of N-glycan mass spectrometry for clinical diagnostics requires the development of robust high-throughput profiling methods. Still, structural assignment of glycans requires additional information such as MS(2) fragmentation or exoglycosidase digestions. We present a setting which combines a MALDI ionization source with a linear ion trap analyzer. This instrumentation allows automated measurement of samples thanks to the crystal positioning system, combined with MS(n) sequencing options. 2,5-Dihydroxybenzoic acid, commonly used for the analysis of glycans, failed to produce the required reproducibility due to its non-homogeneous crystallization properties. In contrast, alpha-cyano-4-hydroxycinnamic acid provided a homogeneous crystallization pattern and reproducibility of the measurements. Using serum N-glycans as a test sample, we focused on the automation of data collection by optimizing the instrument settings. Glycan structures were confirmed by MS(2) analysis. Although sample processing still needs optimization, this method provides a reproducible and high-throughput approach for measurement of N-glycans using a MALDI-linear ion trap instrument. PMID:19577739

  3. A new ion mobility-linear ion trap instrument for complex mixture analysis.

    PubMed

    Donohoe, Gregory C; Maleki, Hossein; Arndt, James R; Khakinejad, Mahdiar; Yi, Jinghai; McBride, Carroll; Nurkiewicz, Timothy R; Valentine, Stephen J

    2014-08-19

    A new instrument that couples a low-pressure drift tube with a linear ion trap mass spectrometer is demonstrated for complex mixture analysis. The combination of the low-pressure separation with the ion trapping capabilities provides several benefits for complex mixture analysis. These include high sensitivity, unique ion fragmentation capabilities, and high reproducibility. Even though the gas-phase separation and the mass measurement steps are each conducted in an ion filtering mode, detection limits for mobility-selected peptide ions are in the tens of attomole range. In addition to ion separation, the low-pressure drift tube can be used as an ion fragmentation cell yielding mobility-resolved fragment ions that can be subsequently analyzed by multistage tandem mass spectrometry (MS(n)) methods in the ion trap. Because of the ion trap configuration, these methods can be comprised of any number (limited by ion signal) of collision-induced dissociation (CID) and electron transfer dissociation (ETD) processes. The high reproducibility of the gas-phase separation allows for comparison of two-dimensional ion mobility spectrometry (IMS)-MS data sets in a pixel-by-pixel fashion without the need for data set alignment. These advantages are presented in model analyses representing mixtures encountered in proteomics and metabolomics experiments. PMID:25068446

  4. [Ln(III)-Mn(II)-Ln(III)] heterometallic compounds: rare linear SMMs with divalent manganese ions.

    PubMed

    Li, Xiao-Lei; Min, Fan-Yong; Wang, Chao; Lin, Shuang-Yan; Liu, Zhiliang; Tang, Jinkui

    2015-02-21

    The reaction of Mn(OAc)2·4H2O and Ln(NO3)3·6H2O with N-(2-aminopropyl)-2-hydroxybenzamide and salicylic aldehyde in methanol/methylene dichloride produces yellow crystals of Ln2Mn(C7H5O2)8 (Ln = Gd (), Tb (), Dy (), Ho () and Er ()), in the presence of triethylamine. Three metal ions are connected by six μ2-phenolate oxygen atoms of six salicylic aldehyde ligands, resulting in perfect linear [Ln(III)-Mn(II)-Ln(III)] structures. Magnetic studies of these complexes have been performed and AC susceptibility measurements show the presence of a temperature-dependent out-of-phase ac signal for complexes and indicating single-molecule magnet (SMM) behavior. The Dy(III)2Mn(II) compound shows double relaxation pathways which may originate from the single ion behavior of individual Dy(III) ions and the weak coupling between Dy(III) and Mn(II) ions, respectively. The Ueff of 92.4(2) K is a relatively high value among 3d-4f SMMs. Moreover, complexes and represent the first linear Mn-Ln SMMs containing only divalent manganese ions as far as we know. The result suggests the positive effects of magnetic coupling to enhance their SMM behavior, presenting a promising strategy for constructing efficient heterometallic SMMs. PMID:25601415

  5. Giant colloidal silver crystals for low-loss linear and nonlinear plasmonics

    PubMed Central

    Wang, Chun-Yuan; Chen, Hung-Ying; Sun, Liuyang; Chen, Wei-Liang; Chang, Yu-Ming; Ahn, Hyeyoung; Li, Xiaoqin; Gwo, Shangjr

    2015-01-01

    The development of ultrasmooth, macroscopic-sized silver (Ag) crystals exhibiting reduced losses is critical to fully characterize the ultimate performance of Ag as a plasmonic material, and to enable cascaded and integrated plasmonic devices. Here we demonstrate the growth of single-crystal Ag plates with millimetre lateral sizes for linear and nonlinear plasmonic applications. Using these Ag crystals, surface plasmon polariton propagation lengths beyond 100 μm in the red wavelength region are measured. These lengths exceed the predicted values using the widely cited Johnson and Christy data. Furthermore, they allow the fabrication of highly reproducible plasmonic nanostructures by focused ion beam milling. We have designed and fabricated double-resonant nanogroove arrays using these crystals for spatially uniform and spectrally tunable second-harmonic generation. In conventional ‘hot-spot'-based nonlinear processes such as surface-enhanced Raman scattering and second-harmonic generation, strong enhancement can only occur in random, localized regions. In contrast, our approach enables uniform nonlinear signal generation over a large area. PMID:26174058

  6. Effect of irradiation of swift heavy ions on dyes-doped KDP crystals for laser applications

    NASA Astrophysics Data System (ADS)

    Kumaresan, P.; Moorthy Babu, S.; Anbarasan, P. M.

    2008-04-01

    The organic dyes (amaranth, rhodamine and methyl orange) are doped in potassium dihydrogen phosphate (KDP) crystals. Influences of super saturation and dye concentration in the solution, on the color and crystal habit of KDP, were observed. Amaranth in the solution at low super saturation and high dye concentration colored the pyramidal section (1 0 1) of the crystals. The highly super saturated solutions produce entirely colored crystals. The concentration of dopants in the mother solution was varied from 0.1 to 10 mol%. The studies on pure and doped KDP crystals clearly indicate the effect of dopants on the crystal structure, in the absorption of IR frequencies and the non-linear optical property. Dye doping improves the NLO properties of the grown crystals. The frequencies with their relative intensities are obtained in FT-IR of pure and doped KDP. The very weak bands for dopants indicate its presence in low concentration. In view of the ever-growing importance of ion beams in optical material processing, this letter reports room temperature MeV Li + ion irradiation-induced depletion of hydrogen from single crystalline KDP which has wide applications as a non-linear optical material in optoelectronics technology. Irradiations have been performed using 50 MeV Li + ions up to a maximum dose of 2.4×10 15 ions cm -2. Simultaneously, detecting the elastically recoiled Li atoms has done hydrogen profiling. Bare KDP crystals show hydrogen loss of 72% at the maximum dose whereas Au-coated samples show that 60 Au layer acts as a barrier to considerably reduce hydrogen depletion from KDP. A possible explanation of these phenomena is suggested.

  7. Cryogenic Linear Ion Trap for Large-Scale Quantum Simulations

    NASA Astrophysics Data System (ADS)

    Pagano, Guido; Hess, Paul; Kaplan, Harvey; Birckelbaw, Eric; Hernanez, Micah; Lee, Aaron; Smith, Jake; Zhang, Jiehang; Monroe, Christopher

    2016-05-01

    Ions confined in RF Paul traps are a useful tool for quantum simulation of long-range spin-spin interaction models. As the system size increases, classical simulation methods become incapable of modeling the exponentially growing Hilbert space, necessitating quantum simulation for precise predictions. Current experiments are limited to less than 30 qubits due to collisions with background gas that regularly destroys the ion crystal. We present progress toward the construction of a cryogenic ion trap apparatus, which uses differential cryopumping to reduce vacuum pressure to a level where collisions do not occur. This should allow robust trapping of about 100 ions/qubits in a single chain with long lifetimes. Such a long chain will provide a platform to investigate simultaneously cooling of various vibrational modes and will enable quantum simulations that outperform their classical counterpart. Our apparatus will provide a powerful test-bed to investigate a large variety of Hamiltonians, including spin 1 and spin 1/2 systems with Ising or XY interactions. This work is supported by the ARO Atomic Physics Program, the AFOSR MURI on Quantum Measurement and Verification, the IC Fellowship Program and the NSF Physics Frontier Center at JQI.

  8. Cryogenic Linear Ion Trap for Large-Scale Quantum Simulations

    NASA Astrophysics Data System (ADS)

    Kaplan, H. B.; Hess, P. W.; Pagano, G.; Birckelbaw, E. J.; Hernandez, M.; Lee, A. C.; Smith, J.; Zhang, J.; Monroe, C.

    2016-05-01

    Ions confined in RF Paul traps are a useful tool for quantum simulation of long-range spin-spin interaction models. As the system size increases, classical simulation methods become incapable of modeling the exponentially growing Hilbert space, necessitating quantum simulation for precise predictions. Current experiments are limited to less than 30 qubits due to collisions with background gas that regularly destroys the ion crystal. We present progress toward the construction of a cryogenic ion trap apparatus, which uses differential cryopumping to reduce vacuum pressure to a level where collisions do not occur. This should allow robust trapping of about 100 ions/qubits in a single chain with long lifetimes. Such a long chain will provide a platform to investigate simultaneously cooling of various vibrational modes and will enable quantum simulations that outperform their classical counterpart. Our apparatus will provide a powerful test-bed to investigate a large variety of Hamiltonians, including spin 1 and spin 1/2 systems with Ising or XY interactions. This work is supported by the ARO Atomic Physics Program, the AFOSR MURI on Quantum Measurement and Verification, and the NSF Physics Frontier Center at JQI.

  9. Coulomb crystals in a cryogenic Paul trap for sympathetic cooling of molecular ions and highly charged ions

    NASA Astrophysics Data System (ADS)

    Windberger, A.; Schwarz, M.; Versolato, O. O.; Baumann, T.; Bekker, H.; Schmöger, L.; Hansen, A. K.; Gingell, A. D.; Klosowski, L.; Kristensen, S.; Schmidt, P. O.; Ullrich, J.; Drewsen, M.; Crespo López-Urrutia, J. R.

    2013-03-01

    Electron beam ion traps used for spectroscopy of highly charged ions (HCI) produce a deep trapping potential leading to high temperatures of the stored ions, and thus limiting the achievable spectral resolution. A novel device at the Max-Planck-Institut für Kernphysik, the Cryogenic linear Paul Trap Experiment (CryPTEx), attached to an electron beam ion trap, provides a new experimental platform to overcome these limitations. The trap assembly operates at a temperature of 4 K and offers optical access for quantum manipulation and imaging of the trapped ions. Since forbidden optical transitions in HCI do not support direct laser cooling, sympathetic cooling with Coulomb crystals of singly charged ions such as Be+ or Mg+ will be applied in order to reach the natural linewidth of optical forbidden transitions in HCI of interest. With the added advantage of long ion trapping times resulting from residual gas pressures of H2 at 4 K below 10-15 mbar, CryPTEx has been commissioned in collaboration with the Ion Trap Group in Århus using rovibrationally cooled MgH+ ions. Strong suppression of the black body radiation at the trap center, ion storage times of about 28 hours, and largely enhanced population of the rovibrational ground state were achieved.

  10. Phase and Radial Motion in Ion Linear Accelerators

    SciTech Connect

    Takeda, H.; Billen, J. H.

    2007-03-29

    Parmila is an ion-linac particle-dynamics code. The name comes from the phrase, "Phase and Radial Motion in Ion Linear Accelerators." The code generates DTL, CCDTL, and CCL accelerating cells and, using a "drift-kick" method, transforms the beam, represented by a collection of particles, through the linac. The code includes a 2-D and 3-D space-charge calculations. Parmila uses data generated by the Poisson Superfish postprocessor SEC. This version of Parmila was written by Harunori Takeda and was supported through Feb. 2006 by James H. Billen. Setup installs executable programs Parmila.EXE, Lingraf.EXE, and ReadPMI.EXE in the LANL directory. The directory LANL\\Examples\\Parmila contains several subdirectories with sample files for Parmila.

  11. LINEAR ELECTROSTATIC INSTABILITY OF THE ELECTRON BEAM ION SOURCE

    SciTech Connect

    Litwin, C.; Vella, M.C.; Sessler, A.

    1981-12-01

    Linear plasma fluid theory is used to study the stability of a cold electron beam in Brillouin equilibrium which passes through a stationary cold ion background, with particular interest in stability for parameters relevant to EBIS devices. Dispersion is studied both analytically and numerically. For {ell}=0, the usual infinite medium two stream instability condition is shown to correspond to a requirement that beam perveance exceed a minimum value, P>33 {micro}pervs; hence, this mode is stable for EBIS (P {approx} l{micro}perv). The Brillouin equilibrium rotation is shown to cause an electron-ion rotating stream instability, which is convectively unstable. The {ell}=1 mode is also found to be unstable. Higher modes numbers, {ell}>1, are unstable, but have reduced growth. Instability is only weakly affected by finite beam radius and boundary conditions.

  12. Phase and Radial Motion in Ion Linear Accelerators

    Energy Science and Technology Software Center (ESTSC)

    2007-03-29

    Parmila is an ion-linac particle-dynamics code. The name comes from the phrase, "Phase and Radial Motion in Ion Linear Accelerators." The code generates DTL, CCDTL, and CCL accelerating cells and, using a "drift-kick" method, transforms the beam, represented by a collection of particles, through the linac. The code includes a 2-D and 3-D space-charge calculations. Parmila uses data generated by the Poisson Superfish postprocessor SEC. This version of Parmila was written by Harunori Takeda andmore » was supported through Feb. 2006 by James H. Billen. Setup installs executable programs Parmila.EXE, Lingraf.EXE, and ReadPMI.EXE in the LANL directory. The directory LANL\\Examples\\Parmila contains several subdirectories with sample files for Parmila.« less

  13. Physics design of linear accelerators for intense ion beams

    SciTech Connect

    Wangler, T.P.

    1988-01-01

    Advances in the physics and technology of linear accelerators for intense ion beams are leading to new methods for the design of such machines. The physical effects that limit beam current and brightness are better understood and provide the criteria for choosing the rf frequency and for determining optimum focusing configurations to control longitudinal and transverse emittances. During the past decade, the use of developments such as the radio-frequency quadrupole, multiple beams, funneling, ramped-field linac tanks, and self-matching linac tanks is leading to greater design flexibility and improved performance capabilities. 39 refs., 3 tabs., 1 fig.

  14. Control of the conformations of ion Coulomb crystals in a Penning trap

    SciTech Connect

    Thompson, R. C.; Mavadia, S.; Goodwin, J. F.; Stutter, G.; Bharadia, S.; Crick, D. R.; Segal, D. M.

    2015-06-29

    Ion Coulomb crystals containing small numbers of ions have been created and manipulated in a wide range of configurations in a Penning trap, from a linear string, through various three-dimensional conformations, to a planar crystal. We show that the dynamics of the system simplifies enormously in a frame which rotates at half the cyclotron frequency and we discuss the effect of the radial cooling laser beam in this frame. Simulations show that the crystal conformations can be reproduced by finding the minimum energy configuration in a frame whose radial potential is modified by the rotation of the ion crystal. The rotation frequency of the crystal deduced from the simulations is consistent with the known laser parameters. We also show that even though the number of ions in our system is small (typically less than 20), the system still behaves like a plasma and its static properties can be calculated using the standard model for a single-component plasma in a trap.

  15. Engineering closed optical transitions in rare-earth ion crystals

    NASA Astrophysics Data System (ADS)

    Bartholomew, John G.; Ahlefeldt, Rose L.; Sellars, Matthew J.

    2016-01-01

    We propose a protocol to preserve the spin state of rare-earth ions when they are optically cycled. This technique uses large magnetic fields to increase the probability of an optically excited ion returning to its initial spin state. This Zeeman enhanced cyclicity is shown to be applicable to non-Kramers ions in various crystals irrespective of the site symmetry. The specific example of Pr3 +:Y2SiO5 is investigated to demonstrate that the protocol can create closed optical transitions even where the point group symmetry of the site is C1. In this example, the predicted cyclicity exceeds 104. This high level of cyclicity extends the usefulness of rare-earth ion crystals for applications in quantum and classical information processing. We explore the use of this technique to enable single-ion, spin-state optical readout and the creation of ensemble-based spectral features that are robust against optical cycling.

  16. Effect of copper ions on the crystallization of bayer aluminium trihydroxide

    NASA Astrophysics Data System (ADS)

    Brown, N.

    1988-02-01

    The effect of copper ions on the crystallization of Bayer aluminium trihydroxide has been examined using the SEM/EDAX technique and particle size analyses. The presence of copper ions, presumably stabilised in solution as the cuprate(II) ion, disrupts the normal crystal growth process and induces secondary nucleation on the aluminium trihydroxide seed crystal surfaces. Although the copper ions adsorb preferentially on the (001) seed crystal surfaces, most of the new crystal formation occurs on the prismatic faces of the pseudo-hexagonal seed crystals. The roughened seed crystal surfaces and the tiny crystalline protrusions promote agglomeration of the seed crystals during subsequent crystallization.

  17. Heavy ion mutagenesis: linear energy transfer effects and genetic linkage

    NASA Technical Reports Server (NTRS)

    Kronenberg, A.; Gauny, S.; Criddle, K.; Vannais, D.; Ueno, A.; Kraemer, S.; Waldren, C. A.; Chatterjee, A. (Principal Investigator)

    1995-01-01

    We have characterized a series of 69 independent mutants at the endogenous hprt locus of human TK6 lymphoblasts and over 200 independent S1-deficient mutants of the human x hamster hybrid cell line AL arising spontaneously or following low-fluence exposures to densely ionizing Fe ions (600 MeV/amu, linear energy transfer = 190 keV/microns). We find that large deletions are common. The entire hprt gene (> 44 kb) was missing in 19/39 Fe-induced mutants, while only 2/30 spontaneous mutants lost the entire hprt coding sequence. When the gene of interest (S1 locus = M1C1 gene) is located on a nonessential human chromosome 11, multilocus deletions of several million base pairs are observed frequently. The S1 mutation frequency is more than 50-fold greater than the frequency of hprt mutants in the same cells. Taken together, these results suggest that low-fluence exposures to Fe ions are often cytotoxic due to their ability to create multilocus deletions that may often include the loss of essential genes. In addition, the tumorigenic potential of these HZE heavy ions may be due to the high potential for loss of tumor suppressor genes. The relative insensitivity of the hprt locus to mutation is likely due to tight linkage to a gene that is required for viability.

  18. Visibility of Young's Interference Fringes: Scattered Light from Small Ion Crystals.

    PubMed

    Wolf, Sebastian; Wechs, Julian; von Zanthier, Joachim; Schmidt-Kaler, Ferdinand

    2016-05-01

    We observe interference in the light scattered from trapped ^{40}Ca^{+} ion crystals. By varying the intensity of the excitation laser, we study the influence of elastic and inelastic scattering on the visibility of the fringe pattern and discriminate its effect from that of the ion temperature and wave-packet localization. In this way we determine the complex degree of coherence and the mutual coherence of light fields produced by individual atoms. We obtain interference fringes from crystals consisting of two, three, and four ions in a harmonic trap. Control of the trapping potential allows for the adjustment of the interatomic distances and thus the formation of linear arrays of atoms serving as a regular grating of microscopic scatterers. PMID:27203319

  19. The tripole linear ion trap with highly efficient orthogonal ion ejection designed by computer simulations.

    PubMed

    Salazar, Gary A; Masujima, Tsutomu

    2008-05-01

    An ion guide, consisting of three rods carrying three alternating current (AC) voltages symmetrically delayed, called a tripole, was used as a linear ion trap (LIT) and studied by computer simulations. Radial containment of ions was also demonstrated with the pseudopotential which was calculated by approximating the tripole electric potential to the multipoles expansion. This work found a new analyte concentrator, which performs effective ion ejection, and is suitable for use with time-of-flight mass spectrometry. The efficiency of the overall process from the trapping until the ejection was higher than 90%, although some degree of ion spatial and kinetic energy spread which can be corrected with a reflectron was obtained. The reason for the ejection of this tripole linear ion trap (tLIT) lies in the high space available between the rods. The ejection is optimized with the application of focusing voltages, especially suitable for a tripole symmetry (one electrode has a pulse offset voltage and the other two have a fraction of that pulse). The beam is finally well parallelized with a rectangular Einzel lens. PMID:18384193

  20. Crystal structure and magnetic properties of a linear tetranuclear Co(II) cluster.

    PubMed

    Wang, Yingying; Wen, Meixia; Gao, Zhongjun; Sheng, Ning

    2016-09-01

    Polynuclear complexes are an important class of inorganic functional materials and are of interest particularly for their applications in molecular magnets. Multidentate chelating ligands play an important role in the design and syntheses of polynuclear metal clusters. A novel linear tetranuclear Co(II) cluster, namely bis{μ3-(E)-2-[(2-oxidobenzylidene)amino]phenolato}bis{μ2-(E)-2-[(2-oxidobenzylidene)amino]phenolato}bis(1,10-phenanthroline)tetracobalt(II), [Co4(C14H11NO2)4(C12H8N2)2], was prepared under solvothermal conditions through a mixed-ligand synthetic strategy. The structure was determined by X-ray single-crystal diffraction and bulk purity was confirmed by powder X-ray diffraction. The complex molecule has a centrosymmetric tetranuclear chain-like structure and the four Co(II) ions are located in two different coordination environments. The Co(II) ions at the ends of the chain are in a slightly distorted octahedral geometry, while the two inner Co(II) ions are in five-coordinate distorted trigonal bipyramidal environments. A magnetic study reveals ferromagnetic Co(II)...Co(II) exchange interactions for the complex. PMID:27585934

  1. Locations of Bromide Ions in Tetragonal Lysozyme Crystals

    NASA Technical Reports Server (NTRS)

    Lim, Kap; Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

    1998-01-01

    Anions have been shown to play a dominant role in the crystallization of chicken egg-white lysozyme from salt solutions. Previous studies employing X-ray crystallography have found one chloride ion binding site in the tetragonal crystal form of the protein and four nitrate ion binding sites in the monoclinic form. In this study the anion positions in the tetragonal form were determined from the difference Fourier map obtained from lysozyme crystals grown in bromide and chloride solutions. Five possible anion-binding sites were found in this manner. Some of these sites were in pockets containing basic residues while others were near neutral, but polar, residues. The sole chloride ion binding site found in previous studies was confirmed, while four further sites were found which corresponded to the four binding sites found for nitrate ions in monoclinic crystals. The study suggests that most of the anion-binding sites in lysozyme remain unchanged even when different anions and different crystal forms of lysozyme are employed.

  2. Linear Ion Trap for the Mars Organic Molecule Analyzer

    NASA Astrophysics Data System (ADS)

    Brinckerhoff, William; Arevalo, Ricardo; Danell, Ryan; van Amerom, Friso; Pinnick, Veronica; Li, Xiang; Hovmand, Lars; Getty, Stephanie; Mahaffy, Paul; Goesmann, Fred; Steininger, Harald

    2014-05-01

    The 2018 ExoMars rover mission includes the Mars Organic Molecule Analyzer (MOMA) investigation. MOMA will examine the chemical composition of samples acquired from depths of up to two meters below the martian surface, where organics may be protected from radiative and oxidative degradation. When combined with the complement of instruments in the rover's Pasteur Payload, MOMA has the potential to reveal the presence of a wide range of organics preserved in a variety of mineralogical environments, and to begin to understand the structural character and potential origin of those compounds. MOMA includes a linear, or 2D, ion trap mass spectrometer (ITMS) that is designed to analyze molecular composition of (i) gas evolved from pyrolyzed powder samples and separated on a gas chromatograph and (ii) ions directly desorbed from solid samples at Mars ambient pressure using a pulsed laser and a fast-valve capillary ion inlet system. This "dual source" approach gives MOMA unprecedented breadth of detection over a wide range of molecular weights and volatilities. Analysis of nonvolatile, higher-molecular weight organics such as carboxylic acids and peptides even in the presence of significant perchlorate concentrations is enabled by the extremely short (~1 ns) pulses of the desorption laser. Use of the ion trap's tandem mass spectrometry mode permits selective focus on key species for isolation and controlled fragmentation, providing structural analysis capabilities. The flight-like engineering test unit (ETU) of the ITMS, now under construction, will be used to verify breadboard performance with high fidelity, while simultaneously supporting the development of analytical scripts and spectral libraries using synthetic and natural Mars analog samples guided by current results from MSL. ETU campaign data will strongly advise the specifics of the calibration applied to the MOMA flight model as well as the science operational procedures during the mission.

  3. Reversing Molecular Ion Formation for Quantum Simulations in a Coulomb Crystal of Be+ Ions

    NASA Astrophysics Data System (ADS)

    Sawyer, Brian; Bohnet, Justin; Britton, Joseph; Bollinger, John

    2015-05-01

    For more than a decade, the internal states of cold, trapped atomic ions have been used as qubits for quantum logic operations. Penning traps allow for confinement and manipulation of very large ion crystals (>> 100) in 1D, 2D, or 3D configurations. Quantum simulation experiments with 2D crystals in Penning traps rely on engineered couplings between Be+ internal spin and collective ion motion perpendicular to the crystal plane. High-fidelity quantum logic operations require precise knowledge of the crystal mode structure, but mode eigenfrequencies and eigenvectors can shift over time as impurity hydride ions (i.e. BeH+) are formed in the crystal via chemistry with background H2 molecules in the vacuum chamber. To mitigate this, we have demonstrated a single-photon photodissociation scheme for BeH+ that efficiently recovers Be+ ions within the crystal. A commercial excimer laser operating at 157 nm provides the photodissociation light, and we note that a 193 nm excimer should efficiently recover Mg+ and Al+ from their respective hydride species, making this technique applicable to a wide range of ion species used in quantum information experiments. Supported by a NIST-NRC Fellowship.

  4. OPCPA modeling using YCOB as the non-linear crystal

    NASA Astrophysics Data System (ADS)

    Pires, Hugo; Cardoso, Luis; Wemans, João; João, Celso; Figueira, Gonçalo

    2010-04-01

    In this work, we evaluate numerically the performance of the nonlinear crystal yttrium calcium oxyborate (YCOB) as the gain medium in a noncollinear, angularly dispersed beam OPCPA configuration, and compare it to other well-studied crystals. In particular, we study its use in the context of an ultrahigh peak and average power amplifier setup. Possible bandwidths are assessed.

  5. Energy loss of ions in solids: Non-linear calculations for slow and swift ions

    NASA Astrophysics Data System (ADS)

    Arista, Néstor R.

    2002-10-01

    The historical approach to describe the energy loss of swift ions in solids is based on the Bohr, Bethe and Bloch theories. As is well known, the central parameter in these theories is the ratio η= Z1e2/ℏ v, whose value is generally used to delimit the ranges of applicability of the Bohr ( η>1) and Bethe ( η<1) theories. The transition between these regimes can be obtained by changing the ratio Z1/ v, although not by simply changing v. In fact, this scheme breaks down at low velocities, where quantum and non-linear effects arise. This domain is characterized by the strong oscillatory Z1 dependence of the stopping powers. This paper proposes a self-consistent non-linear approach to calculate the energy loss of heavy ions on a wide range of velocities. The model is based on the transport cross-section approach and on a previous extension of the Friedel sum rule for moving ions. The purpose of this study is to develop a non-linear stopping power evaluation method that could be applied at finite ion velocities, bridging the current gap between the low- and high-energy models.

  6. Ion implantation induced blistering of rutile single crystals

    NASA Astrophysics Data System (ADS)

    Xiang, Bing-Xi; Jiao, Yang; Guan, Jing; Wang, Lei

    2015-07-01

    The rutile single crystals were implanted by 200 keV He+ ions with a series fluence and annealed at different temperatures to investigate the blistering behavior. The Rutherford backscattering spectrometry, optical microscope and X-ray diffraction were employed to characterize the implantation induced lattice damage and blistering. It was found that the blistering on rutile surface region can be realized by He+ ion implantation with appropriate fluence and the following thermal annealing.

  7. Highly Non-Linear Optical (NLO) organic crystals

    NASA Technical Reports Server (NTRS)

    Harris, J. Milton

    1987-01-01

    This research project involves the synthesis and characterization of organic materials having powerful nonlinear optical (NLO) properties and the growth of highly ordered crystals and monomolecular films of these materials. Research in four areas is discussed: theoretical design of new materials, characterization of NLO materials, synthesis of new materials and development of coupling procedures for forming layered films, and improvement of the techniques for vapor phase and solution phase growth of high quality organic crystals. Knowledge gained from these experiments will form the basis for experiments in the growth of these crystals.

  8. Linear and non-linear dielectric properties of a short-pitch ferroelectric liquid crystal stabilized by a polymer network.

    PubMed

    Cherfi, Y; Hemine, J; Douali, R; Beldjoudi, N; Ismaili, M; Leblond, J M; Legrand, C; Daoudi, A

    2010-12-01

    Linear and non-linear dielectric measurements were carried out on a ferroelectric liquid crystal stabilized by an anisotropic polymer network. The polymerization process was achieved at room temperature. It was performed from an achiral monomer in the ferroelectric chiral smectic C phase, exhibiting a very short helical pitch and a large polarization. The linear and non-linear dielectric spectroscopy were also completed by textural morphology as well as structural and ferroelectric characterizations. All these measurements were carried out on a pure ferroelectric liquid crystal material and on composite films containing two polymer concentrations. The increase of the polymer network density leads to a decrease of the dielectric strength determined in the linear and non-linear dielectric spectroscopy. The complementarity between the linear and non-linear dielectric measurements and their confrontation with a theoretical model allowed the simultaneous determination of some physical parameters such as macroscopic polarization, rotational viscosity and twist elastic energy. We also discuss the effect of the polymer network density on the obtained physical parameters. PMID:21107879

  9. Topographical studies on GNF crystals of non linear optical origin

    NASA Astrophysics Data System (ADS)

    Khandpekar, M. M.; Pati, S. P.

    2013-02-01

    α-glycine has been combined with equal amount of nitric acid and hydrofluoric acid to form GNF crystals. Transparent and elongated crystals of appreciable sizes (2.5 cm length) useful for dislocation studies have been obtained from solution by slow evaporation in 3-4 weeks time. Crystals were found to be delicate and care is needed while handling them. The external geometry of the crystals was found to vary with composition. Glacial acetic acid (GAA) is found to be universal etching agent. GAA produces well defined elongated etch pits on the habit faces and curved triangular pits on cleavage faces in 15 seconds time. Evidence of impurity inclusions and pits on these inclusions have been detected. The orientation of pits on partial cleavage faces are clearly seen to differ. Occasional presence of long domain lines crossing the field of view has been observed. The curvature of pits edges indicates an optically active material with lower symmetry.

  10. Mechanical phase matching of birefringent non-linear crystals.

    PubMed

    Deyra, Loïc; Balembois, François; Guilbaud, André; Villeval, Philippe; Georges, Patrick

    2014-09-22

    Second-order nonlinear processes such as second harmonic generation or parametric amplification have found numerous applications in the scientific and industrial world, from micromachining to petawatt laser facilities. These nonlinear interactions are mostly carried out in birefringent crystals because of their low cost and the possibility to operate at high powers Phase-matching configurations in birefringent crystals are determined by their refractive indexes. Here, we show that an important mechanical stress can be used to significantly change the phase-matching properties of a birefringent crystal. As an example, we demonstrate the shift of second harmonic non-critical phase matching wavelength of LiB3O5 (LBO) crystal at room temperature from 1200 nm to 1120 nm by applying compressive forces up to 100 MPa. We believe that this mechanical phase matching can be used as an additional degree of freedom to optimize nonlinear optical frequency mixing geometries. PMID:25321800

  11. Influence of crystal orientation and ion bombardment on the nitrogen diffusivity in single-crystalline austenitic stainless steel

    SciTech Connect

    Martinavicius, A.; Abrasonis, G.; Moeller, W.

    2011-10-01

    The nitrogen diffusivity in single-crystalline AISI 316L austenitic stainless steel (ASS) during ion nitriding has been investigated at different crystal orientations ((001), (110), (111)) under variations of ion flux (0.3-0.7 mA cm{sup -2}), ion energy (0.5-1.2 keV), and temperature (370-430 deg. C). The nitrogen depth profiles obtained from nuclear reaction analysis are in excellent agreement with fits using the model of diffusion under the influence of traps, from which diffusion coefficients were extracted. At fixed ion energy and flux, the diffusivity varies by a factor up to 2.5 at different crystal orientations. At (100) orientation, it increases linearly with increasing ion flux or energy. The findings are discussed on the basis of atomistic mechanisms of interstitial diffusion, potential lattice distortions, local decomposition, and ion-induced lattice vibrational excitations.

  12. Influence of crystal orientation and ion bombardment on the nitrogen diffusivity in single-crystalline austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Martinavičius, A.; Abrasonis, G.; Möller, W.

    2011-10-01

    The nitrogen diffusivity in single-crystalline AISI 316L austenitic stainless steel (ASS) during ion nitriding has been investigated at different crystal orientations ((001), (110), (111)) under variations of ion flux (0.3-0.7 mA cm-2), ion energy (0.5-1.2 keV), and temperature (370-430 °C). The nitrogen depth profiles obtained from nuclear reaction analysis are in excellent agreement with fits using the model of diffusion under the influence of traps, from which diffusion coefficients were extracted. At fixed ion energy and flux, the diffusivity varies by a factor up to 2.5 at different crystal orientations. At (100) orientation, it increases linearly with increasing ion flux or energy. The findings are discussed on the basis of atomistic mechanisms of interstitial diffusion, potential lattice distortions, local decomposition, and ion-induced lattice vibrational excitations.

  13. Temperature and heating rate of ion crystals in Penning traps

    SciTech Connect

    Jensen, Marie J.; Hasegawa, Taro; Bollinger, John J.

    2004-09-01

    We have determined the temperature and heating rate of laser-cooled ions in a Penning trap using Doppler laser spectroscopy. Between 10{sup 4} and 10{sup 6} {sup 9}Be{sup +} ions are trapped in a Penning trap and Doppler laser cooled to temperatures of a few millikelvin, where they form ion crystals. This system is an example of a strongly coupled one-component plasma. The ion temperature was measured as a function of time after turning off the laser-cooling. In the solid phase, we measured a heating rate of {approx}65 mK/s. Information about possible heating mechanisms was obtained directly from temperature measurements, and also from measurements of the rate of radial expansion of the ion plasma. We determined that the observed heating is due to collisions with the {approx}4x10{sup -9} Pa residual gas of our vacuum system.

  14. Linear and nonlinear coupled drift and ion acoustic waves in collisional pair ion-electron magnetoplasma

    SciTech Connect

    Mushtaq, A.; Saeed, R.; Haque, Q.

    2011-04-15

    Linear and nonlinear coupled electrostatic drift and ion acoustic waves are studied in inhomogeneous, collisional pair ion-electron plasma. The Korteweg-de Vries-Burgers (KdVB) equation for a medium where both dispersion and dissipation are present is derived. An attempt is made to obtain exact solution of KdVB equation by using modified tanh-coth method for arbitrary velocity of nonlinear drift wave. Another exact solution for KdVB is obtained, which gives a structure of shock wave. Korteweg-de Vries (KdV) and Burgers equations are derived in limiting cases with solitary and monotonic shock solutions, respectively. Effects of species density, magnetic field, obliqueness, and the acoustic to drift velocity ratio on the solitary and shock solutions are investigated. The results discussed are useful in understanding of low frequency electrostatic waves at laboratory pair ion plasmas.

  15. Structural phase transitions and topological defects in ion Coulomb crystals

    SciTech Connect

    Partner, Heather L.; Nigmatullin, Ramil; Burgermeister, Tobias; Keller, Jonas; Pyka, Karsten; Plenio, Martin B.; Retzker, Alex; Zurek, Wojciech Hubert; del Campo, Adolfo; Mehlstaubler, Tanja E.

    2014-11-19

    We use laser-cooled ion Coulomb crystals in the well-controlled environment of a harmonic radiofrequency ion trap to investigate phase transitions and defect formation. Topological defects in ion Coulomb crystals (kinks) have been recently proposed for studies of nonlinear physics with solitons and as carriers of quantum information. Defects form when a symmetry breaking phase transition is crossed non-adiabatically. For a second order phase transition, the Kibble-Zurek mechanism predicts that the formation of these defects follows a power law scaling in the rate of the transition. We demonstrate a scaling of defect density and describe kink dynamics and stability. We further discuss the implementation of mass defects and electric fields as first steps toward controlled kink preparation and manipulation.

  16. Computer simulation of the gap-tripole ion trap with linear injection, 3D ion accumulation, and versatile packet ejection.

    PubMed

    Salazar, Gary A; Masujima, Tsutomu

    2008-09-01

    The behavior of a completely new ion trap is shown with SIMION 7.0 simulations. The simulated trap, which was a mix of a linear and a 3D trap, was made by axially setting two ion guides with a gap between them. Each guide consisted of three rods with three symmetrically delayed radio frequency (rf) voltages (tripole). The "injected" ions were linearly contained by pulsed potentials on the entrance and exit plates. Then the three-dimensional (3D) rf field in the gap, which was created by the tripole special rod arrangement, could trap the ions when the translational energy was dampened by collisions with low-pressure nitrogen. Because the injected ions were trapped in the small gap, the trapping cycle could be repeated many times before ion ejection, so a high concentrated ion cloud could be obtained. This trapping and accumulation methodology is not possible in most conventional multipole linear traps with even number of poles. Compared with quadrupole linear trap at the same rf amplitude, tripole lost more ions due to strong charge repulsion in the ion cloud. However, tripole could catch up the ions at higher voltage. Radial and axial mass-independent ejection of the ions localized in the tripole gap was very simple, compared with conventional linear ion traps that need extra and complicated electrodes for effective axial ejection. PMID:18635376

  17. Freezing of the Nb5 + ion dynamics in AgNbO3 studied by linear and nonlinear dielectric response

    NASA Astrophysics Data System (ADS)

    Miga, S.; Kania, A.; Dec, J.

    2011-04-01

    Linear and nonlinear dielectric measurements of AgNbO3 ceramics and single crystals were carried out for the M phases (77-673 K). The linear dielectric response is dominated by the contribution of the submillimetre relaxational mode related to the Nb5 + ion dynamics (M2-M3). On the other hand, nonlinear dielectric χ3' susceptibility revealed anomalies at three characteristic temperatures: 90, 325 and 448 K. Two later ones are connected with changes of the Nb5 + ion dynamics. At Tf = 448 K a partial freezing of the Nb5 + ion displacement to the anti-polar, antiferroelectric array takes place. At 325 K further freezing of Nb and Ag displacements to the polar weak relaxor ferroelectric or dipolar glass transition occurs. This polar state coexists with the ground antiferroelectric one.

  18. The rise of long-distance entanglement within a linear chain of ions

    NASA Astrophysics Data System (ADS)

    Fogarty, Thomas; Kajari, Endre; Taketani, Bruno G.; Wolf, Alexander; Busch, Thomas; Morigi, Giovanna

    2012-02-01

    One stumbling block which limits our observation of quantum effects in the macroscopic world is decoherence. For this reason the study of decoherence and dissipation in open quantum systems has attracted a lot of attention. It has been shown that the generation of long distance entanglement is possible between oscillators via a harmonic crystal (Wolf et al, EPL, 95(2011) 60008). The aim of this current work is to propose an experimentally feasible setup to test the possibility of the creation of long distance entanglement. For this purpose we consider an ion chain in a linear Paul trap with two embedded impurities, whose transverse modes resemble the two degrees of freedom that we aim to entangle via the rest of the chain. With the aid of appropriately designed laser fields, the dynamics described in (Wolf et al, EPL, 95(2011) 60008) is reproduced. The resulting entanglement between the transverse modes of the impurities is analysed by means of the logarithmic negativity.

  19. Heavy ion passive dosimetry with silver halide single crystals

    NASA Technical Reports Server (NTRS)

    Childs, C. B.; Parnell, T. A.

    1972-01-01

    A method of detecting radiation damage tracks due to heavy particles in large single crystals of the silver halides is described. The tracks, when made visible with a simple electrical apparatus, appear similar to tracks in emulsions. The properties of the crystals, the technique of printing out the tracks, and evidence concerning the threshold energy for registering particles indicates that this method may find application in heavy ion dosimetry. The method has been found to be sensitive to stopping He nuclei and relativistic M group cosmic rays. Some impurities strongly influence the printout of the tracks, and the effects of these impurities are discussed.

  20. Delayed stimulated afterglow from holmium ions in crystals with coactivators

    SciTech Connect

    Petrov, M.V.; Tkachuk, A.M.

    1980-12-01

    Delayed stimulated afterglow from holmium ions in ..cap alpha beta..-SrF/sub 2/-YF/sub 3/ crystals was observed and investigated. This took the form of several series of emission spikes separated by dark intervals after the action of a single pump pulse. The effect is attributed to some features of the mechanism for population of the upper active level of the lasing holmium ion in the presence of sensitizer ions. It is found that in order to observe the effect, the system must incorporate a metastable level from which energy transfer to the active level provides an independent ''additional pumping'' system for the holmium ions acting over times much longer than the pump pulse duration.

  1. Efficient rotational cooling of Coulomb-crystallized molecular ions by a helium buffer gas.

    PubMed

    Hansen, A K; Versolato, O O; Kłosowski, L; Kristensen, S B; Gingell, A; Schwarz, M; Windberger, A; Ullrich, J; López-Urrutia, J R Crespo; Drewsen, M

    2014-04-01

    The preparation of cold molecules is of great importance in many contexts, such as fundamental physics investigations, high-resolution spectroscopy of complex molecules, cold chemistry and astrochemistry. One versatile and widely applied method to cool molecules is helium buffer-gas cooling in either a supersonic beam expansion or a cryogenic trap environment. Another more recent method applicable to trapped molecular ions relies on sympathetic translational cooling, through collisional interactions with co-trapped, laser-cooled atomic ions, into spatially ordered structures called Coulomb crystals, combined with laser-controlled internal-state preparation. Here we present experimental results on helium buffer-gas cooling of the rotational degrees of freedom of MgH(+) molecular ions, which have been trapped and sympathetically cooled in a cryogenic linear radio-frequency quadrupole trap. With helium collision rates of only about ten per second--that is, four to five orders of magnitude lower than in typical buffer-gas cooling settings--we have cooled a single molecular ion to a rotational temperature of 7.5(+0.9)(-0.7) kelvin, the lowest such temperature so far measured. In addition, by varying the shape of, or the number of atomic and molecular ions in, larger Coulomb crystals, or both, we have tuned the effective rotational temperature from about 7 kelvin to about 60 kelvin by changing the translational micromotion energy of the ions. The extremely low helium collision rate may allow for sympathetic sideband cooling of single molecular ions, and eventually make quantum-logic spectroscopy of buffer-gas-cooled molecular ions feasible. Furthermore, application of the present cooling scheme to complex molecular ions should enable single- or few-state manipulations of individual molecules of biological interest. PMID:24670662

  2. Mesogenic linear azobenzene polymer-stabilized nematic liquid crystals

    SciTech Connect

    Bagramyan, Arutyun; Thibault-Maheu, Olivier; Galstian, Tigran; Bessette, Andre; Zhao, Yue

    2011-03-15

    We describe the detailed study of a polymer stabilized liquid crystal compound, which was created by using a reactive (monofunctional) azobenzene mesogenic guest and a nematic liquid crystal host. The resonant interaction of light with the azobenzene segment of the guest and the mesogenic nature of the latter enable the optical alignment of host molecules and the permanent fixing of that orientation by means of UV polymerization of the guest. We use dynamic spectral, polarimetric, and scattering techniques to study the orientational ordering and interaction of the guest-host system. We show that the uniform UV polymerization of this compound results in a low scattering material system with dielectric and elastic properties that are relatively close to those of the host, while still providing the capacity for optical configuration of its morphology.

  3. Ionic and electronic processes in non-linear optical crystals

    NASA Astrophysics Data System (ADS)

    Ogorodnikov, Igor N.; Yakovlev, Victor Yu.

    2005-01-01

    The paper presents the results of a study of the formation and decay of lattice defects in nonlinear optical crystals of NH4H2PO4 (ADP), KH2PO4 (KDP), Li2B4O7 (LTB) and LiB3O5 (LBO) with a sublattice of mobile hydrogen (ADP, KDP) and lithium (LTB, LBO) cations. By means of the luminescent and absorption optical spectroscopy with (the) a nanosecond time resolution under excitation with an electron beam, it was revealed that the optical absorption of these crystals in the visible and UV spectral ranges is produced by optical hole-transitions from the local defect level to the valence band states. The valence band density of the states determines the optical absorption spectral profile, and the relaxation kinetics is rated by the interdefect radiationless tunnel recombination between the trapped hole center and the H0 and Li0 electron trapped centers. At 290 K, the H0 and Li0 centers are subject to thermally stimulated migration. All manifestations of a radiative recombination observed in these crystals are accounted for by the involvement of additional electronic and hole centers of a different nature in the recombination process.

  4. An ion trap built with photonic crystal fibre technology

    SciTech Connect

    Lindenfelser, F. Keitch, B.; Kienzler, D.; Home, J. P.; Bykov, D.; Uebel, P.; Russell, P. St. J.

    2015-03-15

    We demonstrate a surface-electrode ion trap fabricated using techniques transferred from the manufacture of photonic-crystal fibres. This provides a relatively straightforward route for realizing traps with an electrode structure on the 100 micron scale with high optical access. We demonstrate the basic functionality of the trap by cooling a single ion to the quantum ground state, allowing us to measure a heating rate from the ground state of 787 ± 24 quanta/s. Variation of the fabrication procedure used here may provide access to traps in this geometry with trap scales between 100 μm and 10 μm.

  5. An ion trap built with photonic crystal fibre technology.

    PubMed

    Lindenfelser, F; Keitch, B; Kienzler, D; Bykov, D; Uebel, P; Schmidt, M A; Russell, P St J; Home, J P

    2015-03-01

    We demonstrate a surface-electrode ion trap fabricated using techniques transferred from the manufacture of photonic-crystal fibres. This provides a relatively straightforward route for realizing traps with an electrode structure on the 100 micron scale with high optical access. We demonstrate the basic functionality of the trap by cooling a single ion to the quantum ground state, allowing us to measure a heating rate from the ground state of 787 ± 24 quanta/s. Variation of the fabrication procedure used here may provide access to traps in this geometry with trap scales between 100 μm and 10 μm. PMID:25832211

  6. Linear electronic field time-of-flight ion mass spectrometers

    DOEpatents

    Funsten, Herbert O.

    2010-08-24

    Time-of-flight mass spectrometer comprising a first drift region and a second drift region enclosed within an evacuation chamber; a means of introducing an analyte of interest into the first drift region; a pulsed ionization source which produces molecular ions from said analyte of interest; a first foil positioned between the first drift region and the second drift region, which dissociates said molecular ions into constituent atomic ions and emits secondary electrons; an electrode which produces secondary electrons upon contact with a constituent atomic ion in second drift region; a stop detector comprising a first ion detection region and a second ion detection region; and a timing means connected to the pulsed ionization source, to the first ion detection region, and to the second ion detection region.

  7. Ion Bernstein instability in the magnetosphere: linear dispersion theory

    SciTech Connect

    Gary, S Peter; Liu, Kaijun; Winske, Dan

    2010-12-10

    Nonthermal ion velocity distributions may drive kinetic instabilities which lead to enhanced field fluctuations near {omega}{sub r} {approx} {Omega}{sub p} in the magnetosphere. These fluctuations resonate with, and thus scatter, both ions and electrons. Ions are thermalized. Fast electrons undergo both pitch-angle scattering and acceleration.

  8. Ion Beam Slicing of Single Crystal Oxide Thin Films

    SciTech Connect

    Thevuthasan, Suntharampillai; Shutthanandan, V; Jiang, Weilin; Weber, William J.; DB Poker, SC Moss, K-H Heinig

    2001-04-25

    Epitaxial thin film liftoff using the ion-slicing method has been applied to SrTiO single crystals. Rutherford backscattering spectrometry along with channeling (RBS/C) has been used to investigate the relative disorder as a function of temperature from the samples that were irradiated by 40 KeV hydrogen ions to a fluence of 5.0x10 16 H/cm. Hydrogen profiles were also measured as a function of annealing temperature to understand the role of hydrogen in the ion slicing process. Film cleavage occurred during or after annealing at 570 K, and cleaved film has been successfully transferred to a silicon substrate using ceramic adhesive.

  9. Ion implantation for manufacturing bent and periodically bent crystals

    SciTech Connect

    Bellucci, Valerio; Camattari, Riccardo; Guidi, Vincenzo Mazzolari, Andrea; Paternò, Gianfranco; Lanzoni, Luca

    2015-08-10

    Ion implantation is proposed to produce self-standing bent monocrystals. A Si sample 0.2 mm thick was bent to a radius of curvature of 10.5 m. The sample curvature was characterized by interferometric measurements; the crystalline quality of the bulk was tested by X-ray diffraction in transmission geometry through synchrotron light at ESRF (Grenoble, France). Dislocations induced by ion implantation affect only a very superficial layer of the sample, namely, the damaged region is confined in a layer 1 μm thick. Finally, an elective application of a deformed crystal through ion implantation is here proposed, i.e., the realization of a crystalline undulator to produce X-ray beams.

  10. Adsorption of ions onto nanosolids dispersed in liquid crystals: Towards understanding the ion trapping effect in nanocolloids

    NASA Astrophysics Data System (ADS)

    Garbovskiy, Yuriy

    2016-05-01

    The ion capturing effect in liquid crystal nanocolloids was quantified by means of the ion trapping coefficient. The dependence of the ion trapping coefficient on the concentration of nano-dopants and their ionic purity was calculated for a variety of nanosolids dispersed in liquid crystals: carbon nanotubes, graphene nano-flakes, diamond nanoparticles, anatase nanoparticles, and ferroelectric nanoparticles. The proposed method perfectly fits existing experimental data and can be useful in the design of highly efficient ion capturing nanomaterials.

  11. The JPL Hg(sup +) Extended Linear Ion Trap Frequency Standard: Status, Stability, and Accuracy Prospects

    NASA Technical Reports Server (NTRS)

    Tjoelker, R. L.; Prestage, J. D.; Maleki, L.

    1996-01-01

    Microwave frequency standards based on room temperature (sup 199)Hg(sup +) ions in a Linear Ion Trap (LITS) presently achieve a Signal to Noise and line Q inferred short frequency stability. Long term stability has been measured for averaging intervals up to 5 months with apparent sensitivity to variations in ion number/temperature limiting the flicker floor.

  12. Production of Ar{sup q+} ions with a tandem linear Paul trap

    SciTech Connect

    Higaki, H. Nagayasu, K.; Iwai, T.; Ito, K.; Okamoto, H.

    2015-06-29

    A tandem linear Paul trap was used to create highly charged Argon ions by electron impact ionizations. By improving the operation scheme, the production of Ar{sup 4+} ions was confirmed. Possible improvements for the future experiments with laser cooled Ca{sup +} ions are suggested.

  13. Diffraction-induced laser pulse splitting in a linear photonic crystal

    SciTech Connect

    Bushuev, V. A.; Mantsyzov, B. I.; Skorynin, A. A.

    2009-05-15

    We demonstrate analytically a linear optical property of photonic crystals--diffraction-induced incident optical pulse splitting in two pulses propagating with different group velocities in a linear photonic crystal. The reason of this phenomenon is in spatially inhomogeneous field localization within the photonic crystal in case of the Bragg diffraction at the Laue scheme. The field of the fast first pulse is mainly localized within low refractive index layers, whereas the slow second pulse field is mostly in high refractive index layers. Changing optical properties of either high-index or low-index layers of periodical multilayer structure, it is possible to control parameters of each propagating pulse separately. The distance between two transmitted and two diffractively reflected output pulses can be controlled by varying the crystal thickness and modulation depth of the refractive index.

  14. Adding Mono- and Multivalent Ions to Lyotropic Chromonic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Tortora, Luana; Park, Heung-Shik; Antion, Kelly; Woolwerton, Chris; Finotello, Daniele; Lavrentovich, Oleg

    2006-03-01

    Lyotropic Chromonic Liquid Crystals (LCLCs) are a distinct class of liquid crystals formed in aqueous solutions by molecules with rigid polyaromatic cores and ionic groups at the periphery [1-4]. The phase diagrams of these materials should depend on entropic factors (as in the Onsager model) and electrostatic interactions. Using optical polarizing microscopy, we studied the effects of mono- and multivalent ions on the phase diagrams of Blue 27 [3] and Sunset Yellow [2]. The monovalent ions change the temperatures of phase transitions, as described in [4], while the effect of multivalent ions is more dramatic and, in addition to the changed temperatures of phase transitions by tens of degrees, it often involves condensation of LCLC aggregates into domains with birefringence much higher than that in a normal nematic phase. Work supported by OBR B-7844. [1]J. Lydon, Current Opin. Colloid & Interface Sci. 3, 458 (1998);8, 480-489 (2004); [2]V. R. Horowitz, L. A. Janowitz, A. L. Modic, P. J. Heiney, and P. J. Collings, 2005, Phys. Rew. E 72, 041710; [3]Yu. A. Nastishin, H. Liu, T. Schneider, T., V. Nazarenko, R. Vasyuta, S. V. Shiyanovskii, and O. D. Lavrentovich, 2005, Phys. Rev. E 72, 041711; [4]A.F. Kostko, B. H. Cipriano, O. A. Pinchuk, L. Ziserman, M. A. Anisimov, D. Danino, and S. R. Raghavan. J. Phys. Chem. B 109, 19126-19133 (2005)

  15. Birefringence and polarization rotator induced by electromagnetically induced transparency in rare earth ion-doped crystals

    NASA Astrophysics Data System (ADS)

    Li, Zhixiang; Liu, Jianji; Yu, Ping; Zhang, Guoquan

    2016-05-01

    The birefringence induced by the electromagnetically induced transparency effect in a {Pr}^{3+}:{Y}_2 {SiO}_5 crystal was studied by using a balanced polarimeter technique. The results show that it is possible to control the polarization state of the output probe beam by adjusting the experimental conditions. Particularly, the coherently prepared {Pr}^{3+}:{Y}_2 {SiO}_5 crystal can serve as a polarization rotator for a linearly polarized input probe beam at the two-photon resonant condition. Such coherent control on the polarization of light should be useful for polarization-based classical and quantum information processing such as all-optical switching, polarization preserving light pulse memory and polarization qubits based on rare earth ion-doped solids.

  16. Interstitial silicon ions in rutile Ti O2 crystals

    NASA Astrophysics Data System (ADS)

    Golden, E. M.; Giles, N. C.; Yang, Shan; Halliburton, L. E.

    2015-04-01

    Electron paramagnetic resonance (EPR) is used to identify a new and unique photoactive silicon-related point defect in single crystals of rutile Ti O2 . The importance of this defect lies in its assignment to interstitial silicon ions and the unexpected establishment of silicon impurities as a major hole trap in Ti O2 . Principal g values of this new S =1 /2 center are 1.9159, 1.9377, and 1.9668 with principal axes along the [1 ¯10 ],[001 ] , and [110 ] directions, respectively. Hyperfine structure in the EPR spectrum shows the unpaired spin interacting equally with two Ti nuclei and unequally with two Si nuclei. These silicon ions are present in the Ti O2 crystals as unintentional impurities. Principal values for the larger of the two Si hyperfine interactions are 91.4, 95.4, and 316.4 MHz with principal axes also along the [1 ¯10 ],[001 ] , and [110 ] directions. The model for the defect consists of two adjacent Si ions, one at a tetrahedral interstitial site and the other occupying a Ti site. Together, they form a neutral nonparamagnetic [Siint-S iTi] 0 complex. When a crystal is illuminated below 40 K with 442-nm laser light, holes are trapped by these silicon complexes and form paramagnetic [Siint-S iTi] + defects, while electrons are trapped at oxygen vacancies. Thermal anneal results show that the [Siint-S iTi] + EPR signal disappears in two steps, coinciding with the release of electrons from neutral oxygen vacancies and singly ionized oxygen vacancies. These released electrons recombine with the holes trapped at the silicon complexes.

  17. Note: A pulsed laser ion source for linear induction accelerators

    SciTech Connect

    Zhang, H.; Zhang, K.; Shen, Y.; Jiang, X.; Dong, P.; Liu, Y.; Wang, Y.; Chen, D.; Pan, H.; Wang, W.; Jiang, W.; Long, J.; Xia, L.; Shi, J.; Zhang, L.; Deng, J.

    2015-01-15

    We have developed a high-current laser ion source for induction accelerators. A copper target was irradiated by a frequency-quadrupled Nd:YAG laser (266 nm) with relatively low intensities of 10{sup 8} W/cm{sup 2}. The laser-produced plasma supplied a large number of Cu{sup +} ions (∼10{sup 12} ions/pulse) during several microseconds. Emission spectra of the plasma were observed and the calculated electron temperature was about 1 eV. An induction voltage adder extracted high-current ion beams over 0.5 A/cm{sup 2} from a plasma-prefilled gap. The normalized beam emittance measured by a pepper-pot method was smaller than 1 π mm mrad.

  18. Note: A pulsed laser ion source for linear induction accelerators

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Zhang, K.; Shen, Y.; Jiang, X.; Dong, P.; Liu, Y.; Wang, Y.; Chen, D.; Pan, H.; Wang, W.; Jiang, W.; Long, J.; Xia, L.; Shi, J.; Zhang, L.; Deng, J.

    2015-01-01

    We have developed a high-current laser ion source for induction accelerators. A copper target was irradiated by a frequency-quadrupled Nd:YAG laser (266 nm) with relatively low intensities of 108 W/cm2. The laser-produced plasma supplied a large number of Cu+ ions (˜1012 ions/pulse) during several microseconds. Emission spectra of the plasma were observed and the calculated electron temperature was about 1 eV. An induction voltage adder extracted high-current ion beams over 0.5 A/cm2 from a plasma-prefilled gap. The normalized beam emittance measured by a pepper-pot method was smaller than 1 π mm mrad.

  19. Crystal structure of a heterotetrameric NMDA receptor ion channel

    PubMed Central

    Karakas, Erkan; Furukawa, Hiro

    2014-01-01

    N -methyl-D-aspartate (NMDA) receptors belong to the family of ionotropic glutamate receptors, which mediate most excitatory synaptic transmission in mammalian brains. Calcium permeation triggered by activation of NMDA receptors is the pivotal event for initiation of neuronal plasticity. Here we show the crystal structure of the intact heterotetrameric GluN1/GluN2B NMDA receptor ion channel at 4 Å. The NMDA receptors are arranged as a dimer of GluN1-GluN2B heterodimers with the two-fold symmetry axis running through the entire molecule composed of an amino terminal domain (ATD), a ligand-binding domain (LBD), and a transmembrane domain (TMD). The ATD and LBD are much more highly packed in the NMDA receptors than non-NMDA receptors, which may explain why ATD regulates ion channel activity in NMDA receptors but not in non-NMDA receptors. PMID:24876489

  20. Development of MS(n) in digitally operated linear ion guides.

    PubMed

    Brabeck, Gregory F; Chen, Huijuan; Hoffman, Nathan M; Wang, Liang; Reilly, Peter T A

    2014-08-01

    This publication demonstrates the use of digital waveform manipulation in linear ion guides to trap isolated ions and fragment them before mass analysis by time-of-flight mass spectrometry (TOF-MS). Ion trapping and collection was performed by waveform duty cycle manipulation to create a negative axial potential between the rods and the end-cap electrodes. Ion isolation can be performed by duty cycle manipulation to narrow the range of stable masses while continuing to axially trap the ions. Further ion isolation can then be performed by jumping the quadrupole frequency to each side of the stability zone to eliminate ions above and below the isolated ion mass. Collision-induced dissociation was demonstrated by duty cycle manipulation to either axially or radially excite the ions. The methods for performing these types of excitations are discussed and demonstrated. These techniques can be combined or used separately for MS(n) analysis. The use of frequency and duty cycle manipulation of the applied waveforms simplifies the hardware while greatly increasing the capabilities of linear ion guides and quadrupole time-of-flight mass spectrometers (Q-TOF-MS). Linear quadrupoles can now be used as high efficiency ion traps for collection, isolation, and tandem mass spectrometry at any value of m/z when operated digitally. PMID:24964342

  1. Major Improvements of Quartz Crystal Pulling Sensitivity and Linearity Using Series Reactance

    PubMed Central

    Matko, Vojko; Šafarič, Riko

    2009-01-01

    This paper presents a new method of substantially improving frequency pullability and linearity using reactance in series with an AT fundamental crystal operated with a series load capacitance in the range of 3 to 50 pF and frequencies in the range of 3.5 to 21 MHz. The research describes high quartz pullability and linearity by varying the load capacitance. The paper also gives impedance circuits for crystal unit (3.5 MHz) together with load capacitance and compensation reactance. The experimental results show that the new approach using compensation method of quartz crystal connected in series reactance increases the frequency pulling range by ×25 to ×100 depending on the type of oscillator and compensation factor “k” in the temperature range of 10 to 40 °C. PMID:22408504

  2. Heavy Ion and Proton Induced Single Event Transients in Linear Devices

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Coss, J. R.; Miyahira, T.; Schwartz, H. R.

    1996-01-01

    This paper presents a display of heavy-ion and proton-induced single event transients for selected linear devices. The transient vital signs are serious; low LET threshold, high voltage amplitude and extended pulse duration (microsecs.).

  3. An electrodynamic ion funnel interface for greater sensitivity and higher throughput with linear ion trap mass spectrometers

    SciTech Connect

    Page, Jason S.; Tang, Keqi; Smith, Richard D.

    2007-09-01

    An electrospray ionization interface incorporating an electrodynamic ion funnel has been designed and implemented in conjunction with a linear ion trap mass spectrometer (Thermo Electron, LTQ). We found ion transmission to be greatly improved by replacing the standard capillary-skimmer interface with the capillary-ion funnel interface. An infusion study using a serial dilution of a reserpine solution showed that ion injection times to fill the ion trap were reduced by ~90% which resulted in an ~10-fold increase in reported peak intensities. In liquid chromatography (LC)-MS and LC tandem MS (MS/MS) experiments performed using a proteomic sample from the bacterium, Shewanella oneidensis, the ion funnel interface provided an ~7-fold reduction in ion injection (accumulation) times. In a series of LC-MS/MS experiments we found that more dilute S. oneidensis samples provided more peptide and protein identifications when the ion funnel interface was used in place of the standard interface. This improvement was most pronounced at lower sample concentrations, where extended ion accumulation times are required, resulting in an ~2-fold increase in the number of protein identifications. Implementation of the ion funnel interface with a LTQ Fourier transform (FT) MS requiring much greater ion populations resulted in spectrum acquisition times reduced by ~25 to 50%.

  4. Growth and birefringence studies of semi organic non-linear optical LHB single crystal

    NASA Astrophysics Data System (ADS)

    Jayaramakrishnan, V.; Prasanyaa, T.; Haris, M.; Bhoopathi, G.

    2015-02-01

    In the last few decades nonlinear optical materials are getting attention in the field of optical data storage, telecommunication, second harmonic generation (SHG) and optical signal processing, etc. In the present work we are reporting the single crystal growth of L-Histidine with hydro-bromic acid. The L-Histidine bromide (LHB) single crystals have been harvested from the solution in a span of 34 days by adopting slow cooling solution growth technique. The grown crystals have been subjected to powder X-ray diffraction studies to identify the cell parameters and structure. The crystalline perfection has been defined by rocking curve (HRXRD) analysis. Optical transmission spectra reveal the optical properties of the grown crystals. The Modified channel spectrum (MCS) method has been adopted for the study of spectral dependence of linear birefringence over the wavelength range 480-620 nm. The second harmonic generation efficiency was tested by using Kurtz and Perry method, keeping KDP as reference.

  5. Synthesis, crystal growth and studies on non-linear optical property of new chalcones

    NASA Astrophysics Data System (ADS)

    Sarojini, B. K.; Narayana, B.; Ashalatha, B. V.; Indira, J.; Lobo, K. G.

    2006-09-01

    The synthesis, crystal growth and non-linear optical (NLO) property of new chalcone derivatives are reported. 4-Propyloxy and 4-butoxy benzaldehydes were made to under go Claisen-Schmidt condensation with 4-methoxy, 4-nitro and 4-phenoxy acetophenones to form corresponding chalcones. The newly synthesized compounds were characterized by analytical and spectral data. The Second harmonic generation (SHG) efficiency of these compounds was measured by powder technique using Nd:YAG laser. Among tested compounds three chalcones showed NLO property. The chalcone 1-(4-methoxyphenyl)-3-(4-propyloxy phenyl)-2-propen-1-one exhibited SHG conversion efficiency 2.7 times that of urea. The bulk crystal of 1-(4-methoxyphenyl)-3-(4-butoxyphenyl)-2-propen-1-one (crystal size 65×28×15 mm 3) was grown by slow-evaporation technique from acetone. Microhardness of the crystal was tested by Vicker's microhardness method.

  6. Linear induction accelerator requirements for ion fast ignition

    SciTech Connect

    Logan, G.

    1998-01-26

    Fast ignition (fast heating of DT cores afief compression) reduces driver energy (by 10 X or more) by reducing the implosion velocity and energy for a given fuel compression ratio. For any type of driver that can deliver the ignition energy fast enough, fast ignition increases the target gain compared to targets using fast implosions for central ignition, as long as the energy to heat the core after compression is comparable to or less than the slow compression energy, and as long as the coupling efficiency of the fast ignitor beam to heat the core is comparable to the overall efficiency of compressing the core (in terms of beam energy-to-DT-efficiency). Ion driven fast ignition, compared to laser-driven fast ignition, has the advantage of direct (dE/dx) deposition of beam energy to the DT, eliminating inefficiencies for conversion into hot electrons, and direct ion heating also has a more favorable deposition profile with the Bragg-peak near the end of an ion range chosen to be deep inside a compressed DT core. While Petawatt laser experiments at LLNL have demonstrated adequate light-to-hot-electron conversion efficiency, it is not yet known if light and hot electrons can channel deeply enough to heat a small portion of a IOOOxLD compressed DT core to ignition. On the other hand, lasers with chirped-pulse amplification giving thousand-fold pulse compressions have been demonstrated to produce the short pulses, small focal spots and Petawatt peak powers approaching those required for fast ignition, whereas ion accelerators that can produce sufficient beam quality for similar compression ratios and focal spot sizes of ion bunches have not yet been demonstrated, where an imposed coherent velocity tilt plays the analogous role for beam compression as does frequency chirp with lasers. Accordingly, it is the driver technology, not the target coupling physics, that poses the main challenge to ion-driven fast ignition. As the mainline HIF program is concentrating on

  7. Structure of apo acyl carrier protein and a proposal to engineer protein crystallization through metal ions

    SciTech Connect

    Qiu, Xiayang; Janson, Cheryl A.

    2010-11-16

    A topic of current interest is engineering surface mutations in order to improve the success rate of protein crystallization. This report explores the possibility of using metal-ion-mediated crystal-packing interactions to facilitate rational design. Escherichia coli apo acyl carrier protein was chosen as a test case because of its high content of negatively charged carboxylates suitable for metal binding with moderate affinity. The protein was successfully crystallized in the presence of zinc ions. The crystal structure was determined to 1.1 {angstrom} resolution with MAD phasing using anomalous signals from the co-crystallized Zn{sup 2+} ions. The case study suggested an integrated strategy for crystallization and structure solution of proteins via engineering surface Asp and Glu mutants, crystallizing them in the presence of metal ions such as Zn{sup 2+} and solving the structures using anomalous signals.

  8. Growth and non-linear optical properties of lithium triborate crystals

    NASA Astrophysics Data System (ADS)

    Pylneva, N. A.; Kononova, N. G.; Yurkin, A. M.; Bazarova, G. G.; Danilov, V. I.

    1999-03-01

    The Li 2O-B 2O 3-MoO 3 ternary system was investigated to determine the region of growth of lithium triborate Li 2O·3B 2O 3 (LBO) crystals with good optical properties. The top-seeded solution growth method, the method of spontaneous crystallisation and solid-state reactions were used in this investigation. The phases were defined by the method of X-ray power diffraction. The data obtained in these experiments made it possible to choose the region of compositions of solutions in the Li 2O-B 2O 3-MoO 3 system for the successful growth of LBO single crystals. LBO single crystals, up to 100×82×45 mm 3 in size and 290 g in weight, were grown free of cracks, bubbles and inclusions. These single crystals were of high optical quality: wavefront distortion (fringe per mm for λ=0.633 μm) was lower than {1}/{150}, absorption losses (0.25 μm< λ<2.5 μm) in the resultant LBO single crystals were lower than 0.005 cm -1, and the damage threshold at λ=1.06 μm, τ=10 ns in the LBO single crystals was more than 10.0 GW/cm 2. High performance non-linear optical elements of various optical orientations, up to 20×20×20 mm 3 in size, were fabricated on our LBO crystals.

  9. Effects of a sheared ion velocity on the linear stability of ITG modes

    NASA Astrophysics Data System (ADS)

    Lontano, M.; Varischetti, M. C.; Lazzaro, E.

    2006-11-01

    The linear dispersion of the ion temperature gradient (ITG) modes, in the presence of a non uniform background ion velocity U∥ = U∥(x) ez, in the direction of the sheared equilibrium magnetic field B0 = B0(x) ez, has been studied in the frame of the two-fluid guiding center approximation, in slab geometry. Generally speaking, the presence of an ion flow destabilizes the oscillations. The role of the excited K-H instability is discussed.

  10. Linear radio frequency quadrupole for the cooling and bunching of radioactive ion beams

    NASA Astrophysics Data System (ADS)

    Darius, G.; Ban, G.; Brégeault, J.; Delahaye, P.; Desrues, Ph.; Durand, D.; Fléchard, X.; Herbane, M.; Labalme, M.; LeBrun, Ch.; Liénard, E.; Mauger, F.; Merrer, Y.; Méry, A.; Naviliat-Cuncic, O.; Szerypo, J.; Vallerand, Ph.; Vandamme, Ch.

    2004-11-01

    A linear radio frequency quadrupole has been built for the transport, cooling, and bunching of radioactive ions extracted from an ECR source. The device uses the buffer gas cooling technique and was designed such as to extend the technique for the cooling of very light ions using H2 as buffer gas. We describe here the technical specifications of the device and present results of the first tests concerning the cooling and bunching of stable ions.

  11. Transfer of excitation energy from host's ions to active dopant ions in oxide single crystals, glasses, and fluorides

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Slawomir M.; Drozdowski, Winicjusz; Swirkowicz, Marek; Majchrowski, Andrzej

    2000-10-01

    Results of absorption and radio luminescence measurements of YalO3, Y3Al5O12, LiTaO3, LiNbO3, YVO4 single crystals and Li2B4O7 single crystals and glasses doped with rare-earth and transition metal ions and LiF crystal were presented. Analysis of excitation energy transfer of x-rays from lattice sites to active ions was performed. Changes in absorption spectra were also analyzed due to (gamma) -quanta irradiation of Nd3+ doped LiYF4 single crystal with a dose of 105 Gy.

  12. Deceleration, precooling, and multi-pass stopping of highly charged ions in Be⁺ Coulomb crystals.

    PubMed

    Schmöger, L; Schwarz, M; Baumann, T M; Versolato, O O; Piest, B; Pfeifer, T; Ullrich, J; Schmidt, P O; López-Urrutia, J R Crespo

    2015-10-01

    Preparing highly charged ions (HCIs) in a cold and strongly localized state is of particular interest for frequency metrology and tests of possible spatial and temporal variations of the fine structure constant. Our versatile preparation technique is based on the generic modular combination of a pulsed ion source with a cryogenic linear Paul trap. Both instruments are connected by a compact beamline with deceleration and precooling properties. We present its design and commissioning experiments regarding these two functionalities. A pulsed buncher tube allows for the deceleration and longitudinal phase-space compression of the ion pulses. External injection of slow HCIs, specifically Ar(13+), into the linear Paul trap and their subsequent retrapping in the absence of sympathetic cooling is demonstrated. The latter proved to be a necessary prerequisite for the multi-pass stopping of HCIs in continuously laser-cooled Be(+) Coulomb crystals. PMID:26520944

  13. Deceleration, precooling, and multi-pass stopping of highly charged ions in Be{sup +} Coulomb crystals

    SciTech Connect

    Schmöger, L. Schwarz, M.; Versolato, O. O.; Baumann, T. M.; Piest, B.; Pfeifer, T.; Crespo López-Urrutia, J. R.; Ullrich, J.; Schmidt, P. O.

    2015-10-15

    Preparing highly charged ions (HCIs) in a cold and strongly localized state is of particular interest for frequency metrology and tests of possible spatial and temporal variations of the fine structure constant. Our versatile preparation technique is based on the generic modular combination of a pulsed ion source with a cryogenic linear Paul trap. Both instruments are connected by a compact beamline with deceleration and precooling properties. We present its design and commissioning experiments regarding these two functionalities. A pulsed buncher tube allows for the deceleration and longitudinal phase-space compression of the ion pulses. External injection of slow HCIs, specifically Ar{sup 13+}, into the linear Paul trap and their subsequent retrapping in the absence of sympathetic cooling is demonstrated. The latter proved to be a necessary prerequisite for the multi-pass stopping of HCIs in continuously laser-cooled Be{sup +} Coulomb crystals.

  14. Linear electrostatic waves in a three-component electron-positron-ion plasma

    SciTech Connect

    Mugemana, A. Moolla, S.; Lazarus, I. J.

    2014-12-15

    Analytical linear electrostatic waves in a magnetized three-component electron-positron-ion plasma are studied in the low-frequency limit. By using the continuity and momentum equations with Poisson's equation, the dispersion relation for the electron-positron-ion plasma consisting of cool ions, and hot Boltzmann electrons and positrons is derived. In the linear regime, the propagation of two possible modes and their evolution are studied. In the cases of parallel and perpendicular propagation, it is shown that these two possible modes are always stable. The present investigation contributes to nonlinear propagation of electrostatic waves in space and the laboratory.

  15. Non-Linear Approach to the Energy Loss of Ions in Solids

    NASA Astrophysics Data System (ADS)

    Arista, Néstor R.; Lifschitz, Agustín F.

    The present work includes the discussion of three main aspects in the area of the energy loss of ions in solids. First we review some of the main features contained in the historical Bohr, Bethe and Bloch theories, and related models based on them. Then we analyze new developments in this area based on a non-linear formulation of the energy loss of ions in a free electron gas. As a final question, we reconsider, from the new perspective of the non-linear approach, some long-standing problems concerning the charge state of ions moving in solids and its relationship with the effective charge concept.

  16. Linear electrostatic waves in a three-component electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Mugemana, A.; Lazarus, I. J.; Moolla, S.

    2014-12-01

    Analytical linear electrostatic waves in a magnetized three-component electron-positron-ion plasma are studied in the low-frequency limit. By using the continuity and momentum equations with Poisson's equation, the dispersion relation for the electron-positron-ion plasma consisting of cool ions, and hot Boltzmann electrons and positrons is derived. In the linear regime, the propagation of two possible modes and their evolution are studied. In the cases of parallel and perpendicular propagation, it is shown that these two possible modes are always stable. The present investigation contributes to nonlinear propagation of electrostatic waves in space and the laboratory.

  17. An electrodynamic ion funnel interface for greater sensitivity and higher throughput with linear ion trap mass spectrometers

    NASA Astrophysics Data System (ADS)

    Page, Jason S.; Tang, Keqi; Smith, Richard D.

    2007-09-01

    An electrospray ionization interface incorporating an electrodynamic ion funnel has been designed and implemented on a linear ion trap mass spectrometer (Thermo Electron, LTQ). We found ion transmission to be greatly improved by replacing the standard capillary-skimmer interface with the capillary-ion funnel interface. An infusion study using a serial dilution of a reserpine solution showed that ion injection (accumulation) times to fill the ion trap at a given automatic gain control (AGC) target value were reduced by ~90% which resulted in an ~10-fold increase in peak intensities. In liquid chromatography tandem MS (LC-MS/MS) experiments performed using a global protein digest sample from the bacterium, Shewanella oneidensis, more peptides and proteins were identified when the ion funnel interface was used in place of the standard interface. This improvement was most pronounced at lower sample concentrations, where extended ion accumulation times are required, resulting in an ~2-fold increase in the number of protein identifications. Implementation of the ion funnel interface on a LTQ Fourier transform (FT) mass spectrometer showed a ~25-50% reduction in spectrum acquisition time. The duty cycle improvement in this case was due to the ion accumulation event contributing a larger portion to the total spectrum acquisition time.

  18. Broad spectrum drug screening using liquid chromatography-hybrid triple quadrupole linear ion trap mass spectrometry.

    PubMed

    Stone, Judy

    2010-01-01

    Centrifuged urine, internal standard (promazine), and ammonium formate buffer are mixed in an autosampler vial to achieve a 10-fold dilution of the specimen. Without additional pretreatment, 10 microL of the sample is injected onto a C18 reverse phase column for gradient analysis with ammonium formate/acetonitrile mobile phases. Drugs in the column eluent become charged in the ion source using positive electrospray atmospheric pressure ionization. Pseudomolecular drug ions are analyzed by a hybrid triple quadrupole linear ion trap mass spectrometer operated with a 264-drug selected ion monitoring (SRM) acquisition method that includes an information-dependant acquisition (IDA) algorithm. PMID:20077072

  19. Numerical computation of the linear stability of the diffusion model for crystal growth simulation

    SciTech Connect

    Yang, C.; Sorensen, D.C.; Meiron, D.I.; Wedeman, B.

    1996-12-31

    We consider a computational scheme for determining the linear stability of a diffusion model arising from the simulation of crystal growth. The process of a needle crystal solidifying into some undercooled liquid can be described by the dual diffusion equations with appropriate initial and boundary conditions. Here U{sub t} and U{sub a} denote the temperature of the liquid and solid respectively, and {alpha} represents the thermal diffusivity. At the solid-liquid interface, the motion of the interface denoted by r and the temperature field are related by the conservation relation where n is the unit outward pointing normal to the interface. A basic stationary solution to this free boundary problem can be obtained by writing the equations of motion in a moving frame and transforming the problem to parabolic coordinates. This is known as the Ivantsov parabola solution. Linear stability theory applied to this stationary solution gives rise to an eigenvalue problem of the form.

  20. Infrared Multiphoton Dissociation of Peptide Cations in a Dual Pressure Linear Ion Trap Mass Spectrometer

    PubMed Central

    Gardner, Myles W.; Smith, Suncerae I.; Ledvina, Aaron R.; Madsen, James A.; Coon, Joshua J.; Schwartz, Jae C.; Stafford, George C.; Brodbelt, Jennifer S.

    2009-01-01

    A dual pressure linear ion trap mass spectrometer was modified to permit infrared multiphoton dissociation (IRMPD) in each of the two cells - the first a high pressure cell operated at nominally 5 × 10-3 Torr and the second a low pressure cell operated at nominally 3 × 10-4 Torr. When IRMPD was performed in the high pressure cell, most peptide ions did not undergo significant photodissociation; however, in the low pressure cell peptide cations were efficiently dissociated with less than 25 ms of IR irradiation regardless of charge state. IRMPD of peptide cations allowed the detection of low m/z product ions including the y1 fragments and immonium ions which are not typically observed by ion trap collision induced dissociation (CID). Photodissociation efficiencies of ~100% and MS/MS (tandem mass spectrometry) efficiencies of greater than 60% were observed for both multiply and singly protonated peptides. In general, higher sequence coverage of peptides was obtained using IRMPD over CID. Further, greater than 90% of the product ion current in the IRMPD mass spectra of doubly charged peptide ions was composed of singly charged product ions compared to the CID mass spectra in which the abundances of the multiply and singly charged product ions were equally divided. Highly charged primary product ions also underwent efficient photodissociation to yield singly charged secondary product ions, thus simplifying the IRMPD product ion mass spectra. PMID:19739654

  1. Crystal Structure of a Potassium Ion Transporter TrkH

    SciTech Connect

    Y Cao; X Jin; H Huang; M Getahun Derebe; E Levin; V Kabaleeswaran; Y Pan; M Punta; J Love; et al.

    2011-12-31

    The TrkH/TrkG/KtrB proteins mediate K{sup +} uptake in bacteria and probably evolved from simple K{sup +} channels by multiple gene duplications or fusions. Here we present the crystal structure of a TrkH from Vibrio parahaemolyticus. TrkH is a homodimer, and each protomer contains an ion permeation pathway. A selectivity filter, similar in architecture to those of K{sup +} channels but significantly shorter, is lined by backbone and side-chain oxygen atoms. Functional studies showed that TrkH is selective for permeation of K{sup +} and Rb{sup +} over smaller ions such as Na{sup +} or Li{sup +}. Immediately intracellular to the selectivity filter are an intramembrane loop and an arginine residue, both highly conserved, which constrict the permeation pathway. Substituting the arginine with an alanine significantly increases the rate of K{sup +} flux. These results reveal the molecular basis of K{sup +} selectivity and suggest a novel gating mechanism for this large and important family of membrane transport proteins.

  2. Crystal structures of a double-barrelled fluoride ion channel

    PubMed Central

    Stockbridge, Randy B.; Kolmakova-Partensky, Ludmila; Shane, Tania; Koide, Akiko; Koide, Shohei; Miller, Christopher; Newstead, Simon

    2016-01-01

    To contend with hazards posed by environmental fluoride, microorganisms export this anion through F--specific ion channels of the Fluc family1–4. Since the recent discovery of Fluc channels, numerous idiosyncratic features of these proteins have been unearthed, including extreme selectivity for F- over Cl- and dual-topology dimeric assembly5–6. To understand the chemical basis for F- permeation and how the antiparallel subunits convene to form a F--selective pore, we solved crystal structures of two bacterial Fluc homologues in complex with three different monobody inhibitors, with and without F- present, to a maximum resolution of 2.1 Å. The structures reveal a surprising “double-barrelled” channel architecture in which two F- ion pathways span the membrane and the dual-topology arrangement includes a centrally coordinated cation, most likely Na+. F- selectivity is proposed to arise from the very narrow pores and an unusual anion coordination that exploits the quadrupolar edges of conserved phenylalanine rings. PMID:26344196

  3. Crystal structures of a double-barrelled fluoride ion channel.

    PubMed

    Stockbridge, Randy B; Kolmakova-Partensky, Ludmila; Shane, Tania; Koide, Akiko; Koide, Shohei; Miller, Christopher; Newstead, Simon

    2015-09-24

    To contend with hazards posed by environmental fluoride, microorganisms export this anion through F(-)-specific ion channels of the Fluc family. Since the recent discovery of Fluc channels, numerous idiosyncratic features of these proteins have been unearthed, including strong selectivity for F(-) over Cl(-) and dual-topology dimeric assembly. To understand the chemical basis for F(-) permeation and how the antiparallel subunits convene to form a F(-)-selective pore, here we solve the crystal structures of two bacterial Fluc homologues in complex with three different monobody inhibitors, with and without F(-) present, to a maximum resolution of 2.1 Å. The structures reveal a surprising 'double-barrelled' channel architecture in which two F(-) ion pathways span the membrane, and the dual-topology arrangement includes a centrally coordinated cation, most likely Na(+). F(-) selectivity is proposed to arise from the very narrow pores and an unusual anion coordination that exploits the quadrupolar edges of conserved phenylalanine rings. PMID:26344196

  4. The measurement results of carbon ion beam structure extracted by bent crystal from U-70 accelerator

    NASA Astrophysics Data System (ADS)

    Afonin, A. G.; Barnov, E. V.; Britvich, G. I.; Chesnokov, Yu A.; Chirkov, P. N.; Durum, A. A.; Kostin, M. Yu; Maisheev, V. A.; Pitalev, V. I.; Reshetnikov, S. F.; Yanovich, A. A.; Nazhmudinov, R. M.; Kubankin, A. S.; Shchagin, A. V.

    2016-07-01

    The carbon ion +6C beam with energy 25 GeV/nucleon was extracted by bent crystal from the U-70 ring. The bent angle of silicon crystal was 85 mrad. About 2×105 particles for 109 circulated ions in the ring were observed in beam line 4a after bent crystal. Geometrical parameters, time structure and ion beam structure were measured. The ability of the bent monocrystal to extract and generate ion beam with necessary parameters for regular usage in physical experiments is shown in the first time.

  5. Broadband ultrasonic linear array using ternary PIN-PMN-PT single crystal.

    PubMed

    Wang, Wei; Zhao, Xiangyong; Or, Siu Wing; Leung, Chung Ming; Zhang, Yaoyao; Jiao, Jie; Luo, Haosu

    2012-09-01

    Ternary Pb(In(1/2)Nb(1/2))O(3)-Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PIN-PMN-PT) single crystal was investigated for potential application in ultrasonic linear array. Orientation and temperature dependences of height extensional electromechanical coupling coefficient k'(33) for PIN-PMN-PT single crystal were studied. It was found that the [001] poled PIN-PMN-PT diced along the [100] direction would achieve a maximum k'(33) (~87%) and the service temperature was up to 110 °C. Ultrasonic linear arrays using PIN-PMN-PT single crystal and PZT ceramic were fabricated and compared. The bandwidth at -6 dB, two-way insertion loss and pulse length of the PIN-PMN-PT array were 98.6%, -45.1 dB, and 0.28 μs, respectively, which were about 25% broader, 3.7dB higher, and 0.08 μs shorter than those of the PZT array. The experimental results agreed well with the theoretical simulation. These superior performances were attributable to the excellent piezoelectric properties of PIN-PMN-PT single crystal. PMID:23020406

  6. The Backscattering Linear Depolarization Ratio of Ice Clouds Composed of Small Ice Crystals

    NASA Astrophysics Data System (ADS)

    Schnaiter, M.; Abdelmonem, A.; Benz, S.; Leisner, T.; Möhler, O.; Wagner, R.

    2009-04-01

    The importance of small ice crystals (< 50 µm) for cirrus cloud radiative properties is a matter of controversial debate, mainly because some measurements seemed to clearly overestimate the number concentrations of small ice particles due to particle shattering on the instrument inlets. On the other hand, there is no doubt that small micrometer-sized ice crystals dominate the particle size distributions of contrails and cirrus clouds emerging from contrails. Polarisation LIDAR is frequently used to investigate the microphysics of contrails and contrail cirrus remotely. These investigations reveal unusually high maximum linear depolarization ratios of 0.5 - 0.7. The knowledge of the link between ice crystal depolarization and their size and shape is a prerequisite for the interpretation of these LIDAR data. Since young contrails consist of relatively small ice crystals with sizes typically less than 10 µm, the scattering matrix of these non-spherical particles can be calculated by the T-matrix method. In order to investigate the relation between the linear backscattering depolarization ratio and the microphysical properties of small ice particles that closely resemble those found in contrails and young cirrus, we started to run dedicated ice crystal nucleation and growth experiments at the large cloud simulation chamber AIDA of Forschungszentrum Karlsruhe. Such studies became feasible after the installation of the new in situ laser scattering and depolarization set up SIMONE at the chamber in 2006. The light scattering measurements are analyzed in the context of the microphysical properties of the ice clouds measured by optical cloud particle spectrometers, single particle imaging, and in situ infrared extinction spectroscopy. We compare our experimental results with theoretical results generated by the T-matrix method for finite cylinders. The results give new insight into the scattering depolarisation properties of small ice crystals grown under simulated

  7. Assembling a ring-shaped crystal in a microfabricated surface ion trap

    DOE PAGESBeta

    Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco; Blain, Matthew; Clark, Craig R.; Clark, Susan; Haltli, Raymond A.; Maunz, Peter; Sterk, Jonathan D.; Tigges, Chris

    2015-09-01

    We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. As a result, approximately 400 40Ca+ ions with an average separation of 9 μm comprise the ion crystal.

  8. Identifying alkali metal inhibitors of crystal growth: a selection criterion based on ion pair hydration energy.

    PubMed

    Farmanesh, Sahar; Alamani, Bryan G; Rimer, Jeffrey D

    2015-09-21

    We show that alkali metals function as effective modifiers of calcium oxalate monohydrate (COM) crystallization wherein alkali-oxalate ion parings reduce the rate of crystal growth by as much as 60%. Our findings reveal a distinct trend in alkali metal efficacy that cannot be explained by colloidal theories or simple descriptors, such as ion size, but is consistent with a theoretical model that accounts for the ion pair's affinity for water. PMID:26242310

  9. PIC Simulations Of Ion Acceleration By Linearly And Circularly Polarized Laser Pulses

    SciTech Connect

    Limpouch, Jiri; Klimo, Ondrej; Psikal, Jan; Tikhonchuk, Vladimir T.; Kawata, Shigeo; Andreev, Alexander A.

    2008-06-24

    Linearly polarized laser radiation accelerates electrons to very high velocities and these electron form a sheath layer on the rear side of thin targets where preferentially protons are accelerated. When mass-limited targets are used, the lateral transport of the absorbed laser energy is reduced and the accelerating field is enhanced. For targets consisting of two ion species, heavier ions facilitate formation of quasi-monoenergetic bunch of lighter ions. For circularly polarized light, fast electron production is suppressed by the absence of the oscillatory component of the ponderomotive force. Ions are accelerated on the front side by the separation field and very thin foil can be accelerated as one massive quasi-neutral block. As all ion species acquire the same velocity, this acceleration mechanism is preferred for heavier ions.

  10. Crystal chemistry of layered structures formed by linear rigid silyl-capped molecules

    PubMed Central

    Lumpi, Daniel; Kautny, Paul; Stöger, Berthold; Fröhlich, Johannes

    2015-01-01

    The crystallization behavior of methylthio- or methylsulfonyl-containing spacer extended Z,Z-bis-ene–yne molecules capped with trimethylsilyl groups obtained by (tandem) thiophene ring fragmentation and of two non-spacer extended analogs were investigated. The rigid and linear molecules generally crystallized in layers whereby the flexibility of the layer interfaces formed by the silyl groups leads to a remarkably rich crystal chemistry. The molecules with benzene and thiophene spacers both crystallized with C2/c symmetry and can be considered as merotypes. Increasing the steric bulk of the core by introduction of ethylenedioxythiophene (EDOT) gave a structure incommensurately modulated in the [010] direction. Further increase of steric demand in the case of a dimethoxythiophene restored periodicity along [010] but resulted in a doubling of the c vector. Two different polytypes were observed, which feature geometrically different layer interfaces (non-OD, order–disorder, polytypes), one with a high stacking fault probability. Oxidation of the methylthio groups of the benzene-based molecule to methylsulfonyl groups led to three polymorphs (two temperature-dependent), which were analyzed by Hirshfeld surface d e/d i fingerprint plots. The analogously oxidized EDOT-based molecule crystallized as systematic twins owing to its OD polytypism. Shortening of the backbone by removal of the aryl core resulted in an enantiomorphic structure and a further shortening by removal of a methylthio-ene fragment again in a systematically twinned OD polytype. PMID:26306200

  11. Descriptors for ions and ion-pairs for use in linear free energy relationships.

    PubMed

    Abraham, Michael H; Acree, William E

    2016-01-22

    The determination of Abraham descriptors for single ions is reviewed, and equations are given for the partition of single ions from water to a number of solvents. These ions include permanent anions and cations and ionic species such as carboxylic acid anions, phenoxide anions and protonated base cations. Descriptors for a large number of ions and ionic species are listed, and equations for the prediction of Abraham descriptors for ionic species are given. The application of descriptors for ions and ionic species to physicochemical processes is given; these are to water-solvent partitions, HPLC retention data, immobilised artificial membranes, the Finkelstein reaction and diffusion in water. Applications to biological processes include brain permeation, microsomal degradation of drugs, skin permeation and human intestinal absorption. The review concludes with a section on the determination of descriptors for ion-pairs. PMID:26189671

  12. Ion Size Effect in Glow Peak Temperature in Binary Mixed Crystals Doped with Divalente Europium

    NASA Astrophysics Data System (ADS)

    Rodriguez-Mijangos, Ricardo; Perez-Salas, Raul

    2006-03-01

    Thermoluminiscence measurements at room temperature of ``beta'' irradiated divalent Europium doped binary mixed alkali halides with KCl and KBr components at several concentrations x in molar fraction. The experiments have been carried out to identify the effect of composition of glow peaks. A typical glow peak has been distinguished for each composition. A linear dependence of its temperature on the composition x has been found. This is associated with the size change of ions Cl and Br. Initial comparative cathodoluminiscent measurement was carried out irradiating a single sample with electrons in an electron microscopy using a 30 KV voltage. With the present results is speculated the behavior of the mixed binary crystals with components KCl and RbCl, doped with divalent Europium.

  13. Development of an Ion Beam Irradiation System for Liquid Crystal Alignment Layer Production

    SciTech Connect

    Matsumoto, Takeshi; Kinoshita, Yuko; Tanii, Masahiro; Tatemichi, Junichi; Konishi, Masashi; Naito, Masao

    2008-11-03

    Ion beam irradiation was employed to produce alignment layers for liquid crystal (LC) displays. The alignment characteristics were compared with those by the conventional rubbing method. Ion incident angle to the films played an important role in LC sample optical qualities. A new ion irradiation method to realize a multi-domain structure for a wide viewing angle was demonstrated.

  14. Estimation of Heavy Ion Densities From Linearly Polarized EMIC Waves At Earth

    SciTech Connect

    Kim, Eun-Hwa; Johnson, Jay R.; Lee, Dong-Hun

    2014-02-24

    Linearly polarized EMIC waves are expected to concentrate at the location where their wave frequency satisfies the ion-ion hybrid (IIH) resonance condition as the result of a mode conversion process. In this letter, we evaluate absorption coefficients at the IIH resonance in the Earth geosynchronous orbit for variable concentrations of helium and azimuthal and field-aligned wave numbers in dipole magnetic field. Although wave absorption occurs for a wide range of heavy ion concentration, it only occurs for a limited range of azimuthal and field-aligned wave numbers such that the IIH resonance frequency is close to, but not exactly the same as the crossover frequency. Our results suggest that, at L = 6.6, linearly polarized EMIC waves can be generated via mode conversion from the compressional waves near the crossover frequency. Consequently, the heavy ion concentration ratio can be estimated from observations of externally generated EMIC waves that have polarization.

  15. Single crystal growth and the electronic structure of orthorhombic Tl3PbBr5: A novel material for non-linear optics

    NASA Astrophysics Data System (ADS)

    Khyzhun, O. Y.; Bekenev, V. L.; Parasyuk, O. V.; Danylchuk, S. P.; Denysyuk, N. M.; Fedorchuk, A. O.; AlZayed, N.; Kityk, I. V.

    2013-03-01

    The X-ray photoelectron core-level and valence-band spectra for pristine and Ar+-ion irradiated surfaces of a Tl3PbBr5 single crystal grown by the Bridgman-Stockbarger method have been measured. The present X-ray photoelectron spectroscopy (XPS) results reveal high chemical stability of Tl3PbBr5 single crystal surface. Total and partial densities of states of constituent atoms of low-temperature (LT) orthorhombic Tl3PbBr5 phase (space group P21212) have been calculated using the full potential linearized augmented plane wave (FP-LAPW) method. The FP-LAPW data reveal that contributions of the Br 4p-like states dominate in the valence band of LT-Tl3PbBr5; they contribute mainly into the top and the central portion of the valence band with also significant contributions throughout the whole valence-band region. The bottom of the valence band of LT-Tl3PbBr5 is composed mainly of the Tl 6s-like states, whilst the unoccupied Pb 6p- and Tl 6p-like states dominate at the bottom of the conduction band. We have explored the crystallochemistry and origin of the chemical bonds in Tl3PbBr5 with respect to the use as mid-IR non-linear optical crystals. Comparison of the spectral dependence to the second order susceptibilities for the titled crystals is performed with respect to the 3.39 μm illuminated crystals. Possibility of the use of Tl3PbBr5 crystals as IR operated non-linear optical crystals is discussed.

  16. Multisectional linear ion trap and novel loading method for optical spectroscopy of electron and nuclear transitions.

    PubMed

    Sysoev, Alexey A; Troyan, Victor I; Borisyuk, Peter V; Krasavin, Andrey V; Vasiliev, Oleg S; Palchikov, Vitaly G; Avdeev, Ivan A; Chernyshev, Denis M; Poteshin, Sergey S

    2015-01-01

    There is a growing need for the development of atomic and nuclear frequency standards because of the important contribution of methods for precision time and frequency measurements to the development of fundamental science, technology, and the economy. It is also conditioned by their potential use in optical clocks and quantum logic applications. It is especially important to develop a universal method that could allow one to use ions of most elements effectively (including ones that are not easily evaporated) proposed for the above-mentioned applications. A linear quadrupole ion trap for the optical spectroscopy of electron and nuclear transitions has been developed and evaluated experimentally. An ion source construction is based on an ultra-high vacuum evaporator in which a metal sample is subjected to an electron beam of energy up to 1 keV, resulting in the appearance of gaseous atoms and ions of various charge state. The linear ion trap consists of five successive quadrupole sections including an entrance quadrupole section, quadrupole mass filter, quadrupole ion guide, ion-trap section, and exit quadrupole section. The same radiofrequency but a different direct current voltage feeds the quadrupole sections. The instrument allows the mass and energy selected trapping of ions from ion beams of various intensities and their localization in the area of laser irradiation. The preliminary results presented show that the proposed instrument and methods allow one to produce effectively up to triply charged thorium ions as well as to trap ions for future spectroscopic study. The instrument is proposed for future use in optical clocks and quantum logic application development. PMID:25906029

  17. Structural and optical properties of Cd2+ ion on the growth of sulphamic acid single crystals

    NASA Astrophysics Data System (ADS)

    Rajyalakshmi, S.; Rao, Valluru Srinivasa; Reddy, P. V. S. S. S. N.; Krishna, V. Y. Rama; Samatha, K.; Rao, K. Ramachandra

    2016-05-01

    Transparent single crystals of Cadmium doped Sulphamic acid (SA) was grown by Conventional slow evaporation solution technique (SEST) which had the size of 13 × 8 × 7 mm3. The grown single crystals have been characterized using single crystal X-ray diffraction UV-visible Spectral studies and Second harmonic generation (SHG) efficiency and the results were discussed. The lattice parameters of the grown Cd2+ ion doped SA crystal are confirmed by single crystal X-ray diffraction and belong to orthorhombic system. Optical transmittance of the crystal was recorded using UV-vis NIR spectrophotometer with its lower cut off wavelength around 259nm. SHG measurements indicate that the SHG efficiency of the grown Cd2+ ion doped SA crystal at a fundamental wavelength of 1064 nm is approximately equal to KDP.

  18. Linear ion trap for second-order Doppler shift reduction in frequency standard applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Janik, Gary R.; Dick, G. John; Maleki, Lute

    1990-01-01

    The authors have designed and are presently testing a novel linear ion trap that permits storage of a large number of ions with reduced susceptibility to the second-order Doppler effect caused by the RF confining fields. This new trap should store about 20 times the number of ions as a conventional RF trap with no corresponding increase in second-order Doppler shift from the confining field. In addition, the sensitivity of this shift to trapping parameters, i.e., RF voltage, RF frequency, and trap size, is greatly reduced. The authors have succeeded in trapping mercury ions and xenon ions in the presence of helium buffer gas. Trap times as long as 2000 s have been measured.

  19. A strain-tunable nanoimprint lithography for linear variable photonic crystal filters.

    PubMed

    Liu, Longju; Khan, Haris A; Li, Jingjing; Hillier, Andrew C; Lu, Meng

    2016-07-22

    This paper presents the fabrication methodology of a linear variable photonic crystal (PC) filter with narrowband reflection that varies over a broad spectral range along the length of the filter. The key component of the linear variable PC filter is a polymer surface-relief grating whose period changes linearly as a function of its position on the filter. The grating is fabricated using a nanoreplica molding process with a wedge-shaped elastomer mold. The top surface of the mold carries the grating pattern and the wedge is formed by a shallow angle between the top and bottom surfaces of the mold. During the replica molding process, a uniaxial force is applied to stretch the mold, resulting in a nearly linearly varying grating period. The period of the grating is determined using the magnitude of the force and the local thickness of the mold. The grating period of the fabricated device spans a range of 421.8-463.3 nm over a distance of 20 mm. A high refractive index dielectric film is deposited on the graded-period grating to act as the waveguide layer of the PC device. The resonance reflection feature of the device varies linearly in a range of 680.2-737.0 nm over the length of the grating. PMID:27276512

  20. A strain-tunable nanoimprint lithography for linear variable photonic crystal filters

    NASA Astrophysics Data System (ADS)

    Liu, Longju; Khan, Haris A.; Li, Jingjing; Hillier, Andrew C.; Lu, Meng

    2016-07-01

    This paper presents the fabrication methodology of a linear variable photonic crystal (PC) filter with narrowband reflection that varies over a broad spectral range along the length of the filter. The key component of the linear variable PC filter is a polymer surface-relief grating whose period changes linearly as a function of its position on the filter. The grating is fabricated using a nanoreplica molding process with a wedge-shaped elastomer mold. The top surface of the mold carries the grating pattern and the wedge is formed by a shallow angle between the top and bottom surfaces of the mold. During the replica molding process, a uniaxial force is applied to stretch the mold, resulting in a nearly linearly varying grating period. The period of the grating is determined using the magnitude of the force and the local thickness of the mold. The grating period of the fabricated device spans a range of 421.8–463.3 nm over a distance of 20 mm. A high refractive index dielectric film is deposited on the graded-period grating to act as the waveguide layer of the PC device. The resonance reflection feature of the device varies linearly in a range of 680.2–737.0 nm over the length of the grating.

  1. Revealing growth defects in non-linear borate single crystals by chemical etching

    NASA Astrophysics Data System (ADS)

    Péter, Á.; Polgár, K.; Beregi, E.

    2000-01-01

    Inorganic cyclic borates such as β-BaB 2O 4 (BBO), LiB 3O 5 (LBO), CsLiB 6O 10 (CLBO) and Li 2B 4O 7 (LTB) are excellent non-linear optical (NLO) materials, particularly in the ultraviolet region. Another type of borate is YAl 3(BO 3) 4 (YAB) which is utilized as a laser host and for self-frequency doubling. Growth imperfections causing scattering and absorption of laser beams affect the performance and the use of borate single crystals. Defects, like inclusions, twins, grain boundaries and dislocations form readily in crystals grown by both the high temperature top-seeded solution growth (HTTSSG) method (BBO, LBO, YAB) and the Czochralski technique (CLBO, LTB). Chemical etching methods have been developed on various planes of the different borate crystals, in order to reveal the nature and the distribution of these defects. These methods have successfully been used to characterize NLO borate crystals. The origins of lattice defect formation are discussed in terms of the growth parameters.

  2. Structural, electronic, and linear optical properties of organic photovoltaic PBTTT-C14 crystal

    NASA Astrophysics Data System (ADS)

    Li, Long-Hua; Kontsevoi, Oleg Y.; Rhim, S. H.; Freeman, Arthur J.

    2013-04-01

    Poly(2,5-bis(3-tetradecylthiophen-2yl)thieno(3,2-b)thiophene) (PBTTT-C14) is an important electro-optical polymer, whose three-dimensional crystal structure is somewhat ambiguous and the fundamental electronic and linear optical properties are not well known. We carried out first-principles calculations to model the crystal structure and to study the effect of side-chains on the physical structure and electronic properties. Our calculations suggest that the patterns of side-chain has little direct effect on the valence band maximum and conduction band minimum but they do have impact on the bandgap through changing the π-π stacking distance. By examining the band structure and wave functions, we conclude that the fundamental bandgap of the PBTTT-C14 crystal is determined by the conduction band energy at the Q point. The calculations indicate that the bandgap of PBTTT-C14 crystal may be tunable by introducing different side-chains. The significant peak in the imaginary part of the dielectric function arises from transitions along the polymer backbone axis, as determined by the critical-point analysis and the large optical transition matrix elements in the direction of the backbone.

  3. Negative linear compressibility in a crystal of α-BiB3O6.

    PubMed

    Kang, Lei; Jiang, Xingxing; Luo, Siyang; Gong, Pifu; Li, Wei; Wu, Xiang; Li, Yanchun; Li, Xiaodong; Chen, Chuangtian; Lin, Zheshuai

    2015-01-01

    Negative linear compressibility (NLC), a rare and important mechanical effect with many application potentials, in a crystal of α-BiB3O6 (BIBO) is comprehensively investigated using first-principles calculations and high-pressure synchrotron X-ray diffraction experiments. The results indicate that the BIBO crystal exhibits the second largest NLC among all known inorganic materials over a broad pressure range. This unusual NLC behaviour is due to the rotation and displacement of the rigid [BO3] and [BO4] building units that result in hinge motion in an umbrella-like topology. More importantly, the parallel-polar lone-pair electrons on the Bi(3+) cations act as "umbrella stands" to withstand the B-O hinges, thus significantly enhancing the NLC effect. BIBO presents a unique example of a "collapsible umbrella" mechanism for achieving NLC, which could be applied to other framework materials with lone-pair electrons. PMID:26305262

  4. Amplitude autocorrelation of femtosecond laser pulses using linear photogalvanic effect in sillenite crystals

    NASA Astrophysics Data System (ADS)

    Grachev, A. I.; Romashko, R. V.; Kulchin, Yu. N.; Golik, S. S.; Nippolainen, E.; Kamshilin, A. A.

    2012-06-01

    We demonstrate excitation of the linear photogalvanic current in a Bi12TiO20 crystal by two orthogonally polarized femtosecond laser pulses with detecting the electrical current via charge accumulation on the sample electrodes. Such a setup was used to implement an interferometric autocorrelation technique for characterization of ultrashort light pulses. Integration of the detected current in femtosecond time domain leads to vanishing of a bipolar component of the photogalvanic current which arises due to a pulse chirping. The advantage of the proposed technique is that it produces the electric field correlation function directly without the need for data processing using a compact, robust, and non-expensive detector in the form of a photoconductive cell of a non-centrosymmetric crystal.

  5. Negative linear compressibility in a crystal of α-BiB3O6

    PubMed Central

    Kang, Lei; Jiang, Xingxing; Luo, Siyang; Gong, Pifu; Li, Wei; Wu, Xiang; Li, Yanchun; Li, Xiaodong; Chen, Chuangtian; Lin, Zheshuai

    2015-01-01

    Negative linear compressibility (NLC), a rare and important mechanical effect with many application potentials, in a crystal of α-BiB3O6 (BIBO) is comprehensively investigated using first-principles calculations and high-pressure synchrotron X-ray diffraction experiments. The results indicate that the BIBO crystal exhibits the second largest NLC among all known inorganic materials over a broad pressure range. This unusual NLC behaviour is due to the rotation and displacement of the rigid [BO3] and [BO4] building units that result in hinge motion in an umbrella-like topology. More importantly, the parallel-polar lone-pair electrons on the Bi3+ cations act as “umbrella stands” to withstand the B-O hinges, thus significantly enhancing the NLC effect. BIBO presents a unique example of a “collapsible umbrella” mechanism for achieving NLC, which could be applied to other framework materials with lone-pair electrons. PMID:26305262

  6. Effect of H + ion implantation on structural, morphological, optical and dielectric properties of L-arginine monohydrochloride monohydrate single crystals

    NASA Astrophysics Data System (ADS)

    Sangeetha, K.; Babu, R. Ramesh; Kumar, P.; Bhagvannarayana, G.; Ramamurthi, K.

    2011-06-01

    L-arginine monohydrochloride monohydrate (LAHCl) single crystals have been implanted with 100 keV H + ions at different ion fluence ranging from 10 12 to 10 15 ions/cm 2. Implanted LAHCl single crystals have been investigated for property changes. Crystal surface and crystalline perfection of the pristine and implanted crystals were analyzed by atomic force microscope and high-resolution X-ray diffraction studies, respectively. Optical absorption bands induced by colour centers, refractive index and birefringence, mechanical stability and dielectric constant of implanted crystals were studied at different ion fluence and compared with that of pristine LAHCl single crystal.

  7. INJECTION OF GOLD IONS IN THE AGS BOOSTER WITH LINEAR COUPLING.

    SciTech Connect

    GARDNE,C.; AHRENS,L.; ROSER,T.; ZENO,K.

    1999-03-29

    Linear Coupling, introduced by skew quadrupoles, has been used for several years to enhance the multi-turn injection efficiency of gold and other heavy ions in the AGS Booster. In this paper we describe our latest measurements of the injection process and compare with models.

  8. Ion-hose instability in a long-pulse linear induction accelerator

    NASA Astrophysics Data System (ADS)

    Genoni, Thomas C.; Hughes, Thomas P.

    2003-03-01

    The ion-hose instability is a transverse electrostatic instability which occurs on electron beams in the presence of a low-density ion channel. It is a phenomenon quite similar to the interaction between electron clouds and proton or positron beams in high-energy accelerators and storage rings. In the DARHT-2 accelerator, the 2-kA, 2-μs beam pulse produces an ion channel through impact ionization of the residual background gas (10-7 10-6 torr). A calculation of the linear growth by Briggs indicates that the instability could be strong enough to affect the radiographic application of DARHT, which requires that transverse oscillations be small compared to the beam radius. We present semianalytical theory and 3D particle-in-cell simulations (using the Lsp code) of the linear and nonlinear growth of the instability, including the effects of the temporal change in the ion density and spatially decreasing beam radius. We find that the number of e-foldings experienced by a given beam slice is given approximately by an analytic expression using the local channel density at the beam slice. Hence, in the linear regime, the number of e-foldings increases linearly from head to tail of the beam pulse since it is proportional to the ion density. We also find that growth is strongly suppressed by nonlinear effects at relatively small oscillation amplitudes of the electron beam. This is because the ion oscillation amplitude is several times larger than that of the beam, allowing nonlinear effects to come into play. An analogous effect has recently been noted in electron-proton instabilities in high-energy accelerators and storage rings. For DARHT-2 parameters, we find that a pressure of ≤1.5×10-7 torr is needed to keep the transverse beam oscillation amplitude less than about 20% of the rms beam radius.

  9. Synthesis and Crystal Structure of a Novel Organic Ion-Complex Crystal for Second-Order Nonlinear Optics

    NASA Astrophysics Data System (ADS)

    Okada, Shuji; Masaki, Atsushi; Matsuda, Hiro; Nakanishi, Hachiro; Kato, Masao; Muramatsu, Ryoji; Otsuka, Masaaki

    1990-06-01

    The novel organic ion-complex crystal composed of protonated merocyanine and p-toluenesulfonate anion, i.e., 1-methyl-4-(2-(4-hydroxyphenyl)vinyl)pyridinium 4-toluenesulfonate (MC-PTS), was synthesized for second-order nonlinear optics. Crystal structure analysis revealed that MC-PTS crystallized in the space group of P1, i.e., the most desired space group for waveguide applications where molecular dipoles are perfectly aligned in one direction. It was also pointed out that the tetrahedral sulfonate anion plays the role of a chiral handle to give noncentrosymmetric space groups.

  10. Neutralization of Hydroxide Ion in Melt-Grown NaCl Crystals

    NASA Technical Reports Server (NTRS)

    Otterson, Dumas A.

    1961-01-01

    Many recent studies of solid-state phenomena, particularly in the area of crystal imperfections, have involved the use of melt-grown NaCl single crystals. Quite often trace impurities in these materials have had a prominent effect on these phenomena. Trace amounts of hydroxide ion have been found in melt-grown NaCl crystals. This paper describes a nondestructive method of neutralizing the hydroxide ion in such crystals. Crystals of similar hydroxide content are maintained at an elevated temperature below the melting point of NaCl in a flowing atmosphere containing. dry hydrogen chloride. Heat treatment is continued until an analysis of the test specimens shows no excess hydroxide ion. A colorimetric method previously described4 is used for this analysis.

  11. Finite size corrections to Madelung number. [for ion atoms in ionic crystals

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

    1986-01-01

    It is customary in the study of ionic crystals to assume that the ions are point charges at their respective lattice sites; the corresponding electrostatic energy of one such ion is reducible to Madelung's form, where the Madelung number has a value of 1.7467. This paper considers the modifications in the electrostatic energy when the atomic finite size is treated in more detail. The results are tabulated as a direct correction to Madelung's number for alkali halide cubic crystals.

  12. Hyperchanneling of Ne^10+ ions through the thick <111> Si crystals

    NASA Astrophysics Data System (ADS)

    Borka-Jovanovic, V.; Petrovic, S.; Borka, D.; Neskovic, N.

    2008-07-01

    In this work we investigate the angular distributions of Ne^10+ ions hyperchanneled along the <111> direction in a thick silicon crystals as a function of the reduced crystal thickness. The ion energy is 60 MeV and the reduced crystal thickness, Lambda, is varied from 10 to 21, corresponding to the crystal length from 6.2 to 13.1 mu m. We follow the ion trajectory in the triangular region of the crystal channel determined by the maximum closed equipotential line around the channel axis, where the hyperchanneling occurs. The Henon-Heiles type of the ion-crystal interaction potential is used as the model of the continuum interaction potential obtained assuming the Moliere expression for the ion-atom interaction potential. The angular distributions are generated using the numerical solution of ion's equations of motion in the transverse plane and the computer simulation method. The obtained results show periodicity of the angular distribution, with the period of 0.5. The values of Lambda = 10, 10.5, 11,..., 21, correspond to the beginnings of periodic cycles of the angular distribution. The effect of zero-degree focusing is observed for these values of variable Lambda. Also, one can observe the formation of the symmetrical ridges in the angular distributions around the centre of the scattering angle plane, whose number increases and the average distance between them decreases as the variable Lambda increases.

  13. Evanescent coupling between surface and linear-defect guided modes in phononic crystals

    NASA Astrophysics Data System (ADS)

    Cicek, Ahmet; Salman, Aysevil; Adem Kaya, Olgun; Ulug, Bulent

    2016-01-01

    Evanescent coupling between surface and linear-defect waveguide modes in a two-dimensional phononic crystal of steel cylinders in air is numerically demonstrated. When the ratio of scatterer radii to the lattice constant is set to 0.47 in the square phononic crystal, the two types of modes start interacting if there is one-row separation between the surface and waveguide. Supercell band structure computations through the Finite Element Method suggest that the waveguide band is displaced significantly, whereas the surface band remains almost intact when the waveguide and surface are in close proximity. The two resultant hybrid bands are such that the coupling length, which varies between 8 and 22 periods, initially changes linearly with frequency, while a much sharper variation is observed towards the top of the lower hybrid band. Such small values facilitate the design of compact devices based on heterogeneous coupling. Finite-element simulations demonstrate bilateral coupling behaviour, where waves incident from either the surface or waveguide can efficiently couple to the other side. The coupling lengths calculated from simulation results are in agreement with the values predicted from the supercell band structure. The possible utilisation of the coupling scheme in sensing applications, especially in acoustic Doppler velocimetry, is discussed.

  14. Crystal-field calculations for transition-metal ions by application of an opposing potential

    DOE PAGESBeta

    Zhou, Fei; Aberg, Daniel

    2016-02-16

    We propose a fully ab initio method, the opposing crystal potential (OCP), to calculate the crystal-field parameters of transition-metal impurities in insulator hosts. Through constrained density functional calculations, OCP obtains the constraining Lagrange multipliers, which act as a cancellation potential against the crystal field and lead to spherical d-electron distribution. Furthermore, the method is applied to several insulators doped with Mn4+ and Mn2+ ions and shown to be in good agreement with experiment.

  15. Linear and nonlinear heavy ion-acoustic waves in a strongly coupled plasma

    SciTech Connect

    Ema, S. A. Mamun, A. A.; Hossen, M. R.

    2015-09-15

    A theoretical study on the propagation of linear and nonlinear heavy ion-acoustic (HIA) waves in an unmagnetized, collisionless, strongly coupled plasma system has been carried out. The plasma system is assumed to contain adiabatic positively charged inertial heavy ion fluids, nonextensive distributed electrons, and Maxwellian light ions. The normal mode analysis is used to study the linear behaviour. On the other hand, the well-known reductive perturbation technique is used to derive the nonlinear dynamical equations, namely, Burgers equation and Korteweg-de Vries (K-dV) equation. They are also numerically analyzed in order to investigate the basic features of shock and solitary waves. The adiabatic effects on the HIA shock and solitary waves propagating in such a strongly coupled plasma are taken into account. It has been observed that the roles of the adiabatic positively charged heavy ions, nonextensivity of electrons, and other plasma parameters arised in this investigation have significantly modified the basic features (viz., polarity, amplitude, width, etc.) of the HIA solitary/shock waves. The findings of our results obtained from this theoretical investigation may be useful in understanding the linear as well as nonlinear phenomena associated with the HIA waves both in space and laboratory plasmas.

  16. Quasi-linear pitch angle and energy diffusion of pickup ions near Comet Halley

    NASA Technical Reports Server (NTRS)

    Huddleston, D. E.; Johnstone, A. D.; Coates, A. J.; Neubauer, F. M.

    1991-01-01

    The process of ion pickup in the environment of Halley's comet is studied in order to see if velocity diffusion driven by the observed level of turbulence can explain the observed development of the implanted ion distribution. The theoretical description used is based on a quasi-linear approach and considers the implantation and transport of cometary ions along solar wind flow lines. To make such a study requires some way of extrapolating the measurements on the Giotto trajectory into the upstream region; models for mass loading and turbulence are used. A simplified kinetic equation describing the source, convection, and quasi-linear velocity diffusion of the heavy cometary ions is solved numerically along flow lines parallel to the sun-comet line. Full two-dimensional (pitch angle and velocity) distributions are obtained at positions along the Giotto trajectory, which are compared with measurements. This study finds that quasi-linear theory, with the empirical model for the observed turbulence level, produces the right order of pitch angle diffusion.

  17. Linear and nonlinear heavy ion-acoustic waves in a strongly coupled plasma

    NASA Astrophysics Data System (ADS)

    Ema, S. A.; Hossen, M. R.; Mamun, A. A.

    2015-09-01

    A theoretical study on the propagation of linear and nonlinear heavy ion-acoustic (HIA) waves in an unmagnetized, collisionless, strongly coupled plasma system has been carried out. The plasma system is assumed to contain adiabatic positively charged inertial heavy ion fluids, nonextensive distributed electrons, and Maxwellian light ions. The normal mode analysis is used to study the linear behaviour. On the other hand, the well-known reductive perturbation technique is used to derive the nonlinear dynamical equations, namely, Burgers equation and Korteweg-de Vries (K-dV) equation. They are also numerically analyzed in order to investigate the basic features of shock and solitary waves. The adiabatic effects on the HIA shock and solitary waves propagating in such a strongly coupled plasma are taken into account. It has been observed that the roles of the adiabatic positively charged heavy ions, nonextensivity of electrons, and other plasma parameters arised in this investigation have significantly modified the basic features (viz., polarity, amplitude, width, etc.) of the HIA solitary/shock waves. The findings of our results obtained from this theoretical investigation may be useful in understanding the linear as well as nonlinear phenomena associated with the HIA waves both in space and laboratory plasmas.

  18. Crystal studies, vibrational spectra and non-linear optical properties of L-histidine chloride monohydrate.

    PubMed

    Ben Ahmed, A; Feki, H; Abid, Y; Boughzala, H; Minot, C

    2010-01-01

    This paper presents the results of our calculations on the geometric parameters, vibrational spectra and hyperpolarizability of a non-linear optical material L-histidine chloride monohydrate. Due to the lack of sufficiently precise information on geometric parameters available in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystal of L-histidine chloride monohydrate has been growing by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro-symmetric space group P2(1)2(1)2(1) of orthorhombic system. IR spectrum has been recorded in the range [400-4000 cm(-1)]. All the experimental vibrational bands have been discussed and assigned to normal mode or to combinations on the basis of our calculations. The optimized geometric bond lengths and bond angles obtained by using DFT//B3LYP/6-31G (d) method show a good agreement with the experimental data. The calculated vibrational spectra are in well agreement with the experimental one. To investigate microscopic second-order non-linear optical NLO behavior of the examined complex, the electric dipole mu, the polarizability alpha and the hyperpolarizability beta were computed using DFT//B3LYP/6-31G (d) method. The time-dependent density functional theory (TD-DFT) was employed to descript the molecular electron structure of the title compound using the B3LYP/6-31G (d) method. According to our calculations, L-histidine chloride monohydrate exhibits non-zero beta value revealing microscopic second-order NLO behavior. PMID:19926520

  19. Crystal studies, vibrational spectra and non-linear optical properties of L-histidine chloride monohydrate

    NASA Astrophysics Data System (ADS)

    Ahmed, A. Ben; Feki, H.; Abid, Y.; Boughzala, H.; Minot, C.

    2010-01-01

    This paper presents the results of our calculations on the geometric parameters, vibrational spectra and hyperpolarizability of a non-linear optical material L-histidine chloride monohydrate. Due to the lack of sufficiently precise information on geometric parameters available in literature, theoretical calculations were preceded by re-determination of the crystal X-ray structure. Single crystal of L-histidine chloride monohydrate has been growing by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in the non-Centro-symmetric space group P2 12 12 1 of orthorhombic system. IR spectrum has been recorded in the range [400-4000 cm -1]. All the experimental vibrational bands have been discussed and assigned to normal mode or to combinations on the basis of our calculations. The optimized geometric bond lengths and bond angles obtained by using DFT//B3LYP/6-31G (d) method show a good agreement with the experimental data. The calculated vibrational spectra are in well agreement with the experimental one. To investigate microscopic second-order non-linear optical NLO behavior of the examined complex, the electric dipole μ, the polarizability α and the hyperpolarizability β were computed using DFT//B3LYP/6-31G (d) method. The time-dependent density functional theory (TD-DFT) was employed to descript the molecular electron structure of the title compound using the B3LYP/6-31G (d) method. According to our calculations, L-histidine chloride monohydrate exhibits non-zero β value revealing microscopic second-order NLO behavior.

  20. Kinetics of linear domains in LiNbO{sub 3} single crystals polarized by scanning probe microscopy

    SciTech Connect

    Bo, Huifeng; College of Science, Hebei United University, Tangshan 063009 ; Jin, Yaming; Xu, Tingting; Du, Yingchao; Kan, Yi; Lu, Xiaomei Zhu, Jinsong

    2013-12-16

    Growth and decay processes of linear domains in lithium niobate single crystals fabricated utilizing scanning probe microscopy were investigated. It is found that the initial configuration of linear domains is dependent on the fabrication parameters as scan velocity and voltage. The linear domains decay at the part where the domain width is small for two different processes. A comparison of critical stable domain size between dot and linear domains was carried out. The critical linear domain width is 0.7 times as large as the critical diameter of dot domain at the same sample thickness due to their smaller surface energy.

  1. Third-order nonlinear and linear time-dependent dynamical diffraction of X-rays in crystals.

    PubMed

    Balyan, Minas K

    2016-07-01

    For the first time the third-order nonlinear time-dependent Takagi's equations of X-rays in crystals are obtained and investigated. The third-order nonlinear and linear time-dependent dynamical diffraction of X-rays spatially restricted in the diffraction plane pulses in crystals is investigated theoretically. A method of solving the linear and the third-order nonlinear time-dependent Takagi's equations is proposed. Based on this method, results of analytical and numerical calculations for both linear and nonlinear diffraction cases are presented and compared. PMID:27359140

  2. Linear and nonlinear evolution of the ion resonance instability in cylindrical traps: A numerical study

    SciTech Connect

    Sengupta, M.; Ganesh, R.

    2015-07-15

    Numerical experiments have been performed to investigate the linear and nonlinear dynamics, and energetics of the ion resonance instability in cylindrically confined nonneutral plasma. The instability is excited on a set of parametrically different unstable equilibria of a cylindrical nonneutral cloud, composed of electrons partially neutralized by a much heavier ion species of single ionization. A particle-in-cell code has been developed and employed to carry out these simulations. The results obtained from the initial exponential growth phase of the instability in these numerical experiments are in agreement with the linearised analytical model of the ion resonance instability. As the simulations delve much further in time beyond the exponential growth phase, very interesting nonlinear phenomena of the ion resonance instability are revealed, such as a process of simultaneous wave breaking of the excited poloidal mode on the ion cloud and pinching of the poloidal perturbations on the electron cloud. This simultaneous nonlinear dynamics of the two components is associated with an energy transfer process from the electrons to the ions. At later stages there is heating induced cross-field transport of the heavier ions and tearing across the pinches on the electron cloud followed by an inverse cascade of the torn sections.

  3. Photoelectron-photofragment coincidence spectroscopy in a cryogenically cooled linear electrostatic ion beam trap

    SciTech Connect

    Johnson, Christopher J.; Shen, Ben B.; Poad, Berwyck L. J.; Continetti, Robert E.

    2011-10-15

    A cryogenically cooled linear electrostatic ion beam trap for use in photoelectron-photofragment coincidence (PPC) spectroscopy is described. Using this instrument, anions created in cold, low-duty-cycle sources can be stored for many seconds in a {approx}20 K environment to cool radiatively, removing energetic uncertainties due to vibrationally excited precursor anions. This apparatus maintains a well-collimated beam necessary for high-resolution fragment imaging and the high experimental duty cycle needed for coincidence experiments. Ion oscillation is bunched and phase-locked to a modelocked laser, ensuring temporal overlap between ion bunches and laser pulses and that ions are intersected by the laser only when travelling in one direction. An electron detector is housed in the field-free center of the trap, allowing PPC experiments to be carried out on ions while they are stored and permitting efficient detection of 3-dimensional electron and neutral recoil trajectories. The effects of trapping parameters on the center-of-mass trajectories in the laser-ion interaction region are explored to optimize neutral particle resolution, and the impact of bunching on ion oscillation is established. Finally, an initial demonstration of radiative cooling is presented.

  4. Large Linear Magnetoresistance and Shubnikov-de Hass Oscillations in Single Crystals of YPdBi Heusler Topological Insulators

    NASA Astrophysics Data System (ADS)

    Wang, Wenhong; Du, Yin; Xu, Guizhou; Zhang, Xiaoming; Liu, Enke; Liu, Zhongyuan; Shi, Youguo; Chen, Jinglan; Wu, Guangheng; Zhang, Xi-Xiang

    2013-07-01

    We report the observation of a large linear magnetoresistance (MR) and Shubnikov-de Hass (SdH) quantum oscillations in single crystals of YPdBi Heusler topological insulators. Owning to the successfully obtained the high-quality YPdBi single crystals, large non-saturating linear MR of as high as 350% at 5K and over 120% at 300 K under a moderate magnetic field of 7 T is observed. In addition to the large, field-linear MR, the samples exhibit pronounced SdH quantum oscillations at low temperature. Analysis of the SdH data manifests that the high-mobility bulk electron carriers dominate the magnetotransport and are responsible for the observed large linear MR in YPdBi crystals. These findings imply that the Heusler-based topological insulators have superiorities for investigating the novel quantum transport properties and developing the potential applications.

  5. Design of blade-shaped-electrode linear ion traps with reduced anharmonic contributions

    SciTech Connect

    Deng, K.; Che, H.; Ge, Y. P.; Xu, Z. T.; Yuan, W. H.; Zhang, J.; Lu, Z. H.; Lan, Y.

    2015-09-21

    RF quadrupole linear Paul traps are versatile tools in quantum physics experiments. Linear Paul traps with blade-shaped electrodes have the advantages of larger solid angles for fluorescence collection. But with these kinds of traps, the existence of higher-order anharmonic terms of the trap potentials can cause large heating rate for the trapped ions. In this paper, we theoretically investigate the dependence of higher-order terms of trap potentials on the geometry of blade-shaped traps, and offer an optimized design. A modified blade electrodes trap is proposed to further reduce higher-order anharmonic terms while still retaining large fluorescence collection angle.

  6. Large and Anisotropic Linear Magnetoresistance in Single Crystals of Black Phosphorus Arising From Mobility Fluctuations.

    PubMed

    Hou, Zhipeng; Yang, Bingchao; Wang, Yue; Ding, Bei; Zhang, Xiaoming; Yao, Yuan; Liu, Enke; Xi, Xuekui; Wu, Guangheng; Zeng, Zhongming; Liu, Zhongyuan; Wang, Wenhong

    2016-01-01

    Black Phosphorus (BP) is presently attracting immense research interest on the global level due to its high mobility and suitable band gap for potential application in optoelectronics and flexible devices. It was theoretically predicted that BP has a large direction-dependent electrical and magnetotransport anisotropy. Investigations on magnetotransport of BP may therefore provide a new platform for studying the nature of electron transport in layered materials. However, to the best of our knowledge, magnetotransport studies, especially the anisotropic magnetoresistance (MR) effect in layered BP, are rarely reported. Here, we report a large linear MR up to 510% at a magnetic field of 7 Tesla in single crystals of BP. Analysis of the temperature and angle dependence of MR revealed that the large linear MR in our sample originates from mobility fluctuations. Furthermore, we reveal that the large linear MR of layered BP in fact follows a three-dimensional behavior rather than a two-dimensional one. Our results have implications to both the fundamental understanding and magnetoresistive device applications of BP. PMID:27030141

  7. On the formation of shocks of electromagnetic plane waves in non-linear crystals

    NASA Astrophysics Data System (ADS)

    Christodoulou, Demetrios; Perez, Daniel Raoul

    2016-08-01

    An influential result of F. John states that no genuinely non-linear strictly hyperbolic quasi-linear first order system of partial differential equations in two variables has a global C2-solution for small enough initial data. Inspired by recent work of D. Christodoulou, we revisit John's original proof and extract a more precise description of the behaviour of solutions at the time of shock. We show that John's singular first order quantity, when expressed in characteristic coordinates, remains bounded until the final time, which is then characterised by an inverse density of characteristics tending to zero in one point. Moreover, we study the derivatives of second order, showing again their boundedness when expressed in appropriate coordinates. We also recover John's upper bound for the time of shock formation and complement it with a lower bound. Finally, we apply these results to electromagnetic plane waves in a crystal with no magnetic properties and cubic electric non-linearity in the energy density, assuming no dispersion.

  8. Large and Anisotropic Linear Magnetoresistance in Single Crystals of Black Phosphorus Arising From Mobility Fluctuations

    PubMed Central

    Hou, Zhipeng; Yang, Bingchao; Wang, Yue; Ding, Bei; Zhang, Xiaoming; Yao, Yuan; Liu, Enke; Xi, Xuekui; Wu, Guangheng; Zeng, Zhongming; Liu, Zhongyuan; Wang, Wenhong

    2016-01-01

    Black Phosphorus (BP) is presently attracting immense research interest on the global level due to its high mobility and suitable band gap for potential application in optoelectronics and flexible devices. It was theoretically predicted that BP has a large direction-dependent electrical and magnetotransport anisotropy. Investigations on magnetotransport of BP may therefore provide a new platform for studying the nature of electron transport in layered materials. However, to the best of our knowledge, magnetotransport studies, especially the anisotropic magnetoresistance (MR) effect in layered BP, are rarely reported. Here, we report a large linear MR up to 510% at a magnetic field of 7 Tesla in single crystals of BP. Analysis of the temperature and angle dependence of MR revealed that the large linear MR in our sample originates from mobility fluctuations. Furthermore, we reveal that the large linear MR of layered BP in fact follows a three-dimensional behavior rather than a two-dimensional one. Our results have implications to both the fundamental understanding and magnetoresistive device applications of BP. PMID:27030141

  9. Large and Anisotropic Linear Magnetoresistance in Single Crystals of Black Phosphorus Arising From Mobility Fluctuations

    NASA Astrophysics Data System (ADS)

    Hou, Zhipeng; Yang, Bingchao; Wang, Yue; Ding, Bei; Zhang, Xiaoming; Yao, Yuan; Liu, Enke; Xi, Xuekui; Wu, Guangheng; Zeng, Zhongming; Liu, Zhongyuan; Wang, Wenhong

    2016-03-01

    Black Phosphorus (BP) is presently attracting immense research interest on the global level due to its high mobility and suitable band gap for potential application in optoelectronics and flexible devices. It was theoretically predicted that BP has a large direction-dependent electrical and magnetotransport anisotropy. Investigations on magnetotransport of BP may therefore provide a new platform for studying the nature of electron transport in layered materials. However, to the best of our knowledge, magnetotransport studies, especially the anisotropic magnetoresistance (MR) effect in layered BP, are rarely reported. Here, we report a large linear MR up to 510% at a magnetic field of 7 Tesla in single crystals of BP. Analysis of the temperature and angle dependence of MR revealed that the large linear MR in our sample originates from mobility fluctuations. Furthermore, we reveal that the large linear MR of layered BP in fact follows a three-dimensional behavior rather than a two-dimensional one. Our results have implications to both the fundamental understanding and magnetoresistive device applications of BP.

  10. Electron paramagnetic resonance of Cr3+ ions in ABO3 (A = Sc, Lu, In) diamagnetic crystals

    NASA Astrophysics Data System (ADS)

    Vorotynov, A. M.; Ovchinnikov, S. G.; Rudenko, V. V.; Vorotynova, O. V.

    2016-04-01

    A magnetic resonance method is applied to the investigation of a number of isostructural diamagnetic compounds ABO3 (A = Sc, Lu, In) with small additions of Cr3+ ions ( S = 3/2) sufficient to observe single-ion spectra. It is shown that the resonance spectra for isolated Cr3+ ions can be described to a good accuracy by the ordinary axial spin Hamiltonian for 3 d ions in octahedral oxygen environment. The parameters of the spin Hamiltonian are determined. It is established that Cr3+ ions in these crystals are characterized by easy-axis-type anisotropy.

  11. Assembling a ring-shaped crystal in a microfabricated surface ion trap

    SciTech Connect

    Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco; Blain, Matthew; Clark, Craig R.; Clark, Susan; Haltli, Raymond A.; Maunz, Peter; Sterk, Jonathan D.; Tigges, Chris

    2015-09-01

    We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. As a result, approximately 400 40Ca+ ions with an average separation of 9 μm comprise the ion crystal.

  12. Particle irradiation and electron work function: Fe single crystal bombarded with Ar+ ions

    NASA Astrophysics Data System (ADS)

    Horváth, Ákos; Nagy, Norbert; Schiller, Robert

    2016-07-01

    Accelerated Ar+ ions of 30 keV energy were used to mimic the effect of fast neutrons on Fe single crystal. Both Monte-Carlo calculations and X-ray Photoelectron Spectroscopy (XPS) measurements indicated that the fast ions did not alter the surface causing damage only at several nm depth. The change in the electrode potential, characteristic also to corrosion processes, was determined by the Kelvin method of work function measurement in order to avoid any post-irradiation process. Irradiation with fluences between 5×1014 and 6×1015 cm-2 decreased the electrode potential of the sample by about 60 mV in qualitative agreement with earlier results about the work functions of Fe single crystal and polycrystalline sample. Thus ion irradiation turns the interior of the single crystal into a disordered, polycrystalline substance increasing the crystal's readiness to be corroded.

  13. Enhanced localized energetic ion losses resulting from first-orbit linear and non-linear interactions with Alfvén eigenmodes in DIII-D

    SciTech Connect

    Chen, X.; Heidbrink, W. W.; Kramer, G. J.; Nazikian, R.; Grierson, B. A.; Podesta, M.; Van Zeeland, M. A.; Pace, D. C.; Petty, C. C.; Fisher, R. K.; Zeng, L.; Austin, M. E.

    2014-08-15

    Two key insights into interactions between Alfvén eigenmodes (AEs) and energetic particles in the plasma core are gained from measurements and modeling of first-orbit beam-ion loss in DIII-D. First, the neutral beam-ion first-orbit losses are enhanced by AEs and a single AE can cause large fast-ion displacement. The coherent losses are from born trapped full energy beam-ions being non-resonantly scattered by AEs onto loss orbits within their first poloidal transit. The loss amplitudes scale linearly with the mode amplitude but the slope is different for different modes. The radial displacement of fast-ions by individual AEs can be directly inferred from the measurements. Second, oscillations in the beam-ion first-orbit losses are observed at the sum, difference, and harmonic frequencies of two independent AEs. These oscillations are not plasma modes and are absent in magnetic, density, and temperature fluctuations. The origin of the non-linearity as a wave-particle coupling is confirmed through bi-coherence analysis, which is clearly observed because the coherences are preserved by the first-orbit loss mechanism. An analytic model and full orbit simulations show that the non-linear features seen in the loss signal can be explained by a non-linear interaction between the fast ions and the two independent AEs.

  14. Modification of the crystal structure of gadolinium gallium garnet by helium ion irradiation

    SciTech Connect

    Ostafiychuk, B. K.; Yaremiy, I. P. Yaremiy, S. I.; Fedoriv, V. D.; Tomyn, U. O.; Umantsiv, M. M.; Fodchuk, I. M.; Kladko, V. P.

    2013-12-15

    The structure of gadolinium gallium garnet (GGG) single crystals before and after implantation by He{sup +} ions has been investigated using high-resolution X-ray diffraction methods and the generalized dynamic theory of X-ray scattering. The main types of growth defects in GGG single crystals and radiation-induced defects in the ion-implanted layer have been determined. It is established that the concentration of dislocation loops in the GGG surface layer modified by ion implantation increases and their radius decreases with an increase in the implantation dose.

  15. Island embryo regression driven by a beam of self-ions in the linear regime

    NASA Astrophysics Data System (ADS)

    Flynn, C. P.

    2010-10-01

    The kinetics of island growth and regression are discussed under the approximation of linear response, including the Gibbs-Thompson potential, for a reacting assembly of adatoms and advacancies (thermal defects) on a surface irradiated with a beam of self-ions. First the quasistatic growth or shrinkage rate, for islands of size n less than the critical size \\hat {n} , is calculated for the driven system, exactly, for linear response. This result is employed to determine successively: (i) the regression rate of driven embryo islands with n \\lt \\hat {n} ; and (ii) the structure of the steady state decay chain established when embryos of a particular size n_{0}\\lt \\hat {n} are created by ion beam impacts. The changed embryo distribution caused by irradiation differs markedly from the populations of the embryos at equilibrium.

  16. Tailored Noise Waveform/ Collision-Induced Dissociation of Ions Stored in a Linear Ion Trap Combined with Liquid Chromatography/Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

    SciTech Connect

    Vilkov, Andrey N.; Bogdanov, Bogdan; Pasa-Tolic, Liljiana; Prior, David C.; Anderson, Gordon A.; Masselon, Christophe D.; Moore, Ronald J.; Smith, Richard D.

    2004-11-01

    A new collision-induced dissociation (CID) technique based on broadband tailored noise waveform (TNW) excitation of ions stored in a linear ion trap has been developed. In comparison with the conventional sustained off-resonance irradiation (SORI) CID method commonly used in Fourier transform ion cyclotron resonance mass spectrometry, this MS/MS technique increases throughput by eliminating the long pump-down delay associated with gas introduction into the high vacuum ICR cell region. In addition, the TNW-CID method speeds spectrum acquisition since it does not require Fourier transformation, calculation of resonant frequencies and generation of the excitation waveforms. We demonstrate TNW-CID coupled with on-line capillary reverse phase liquid chromatography separations for identification of peptides. The experimental results are compared with data obtained using conventional quadrupole ion trap MS/MS and SORI-CID MS/MS in an ICR cell.

  17. On the energy spectra of secondary ions emitted from silicon and graphite single crystals

    NASA Astrophysics Data System (ADS)

    Khvostov, V. V.; Khrustachev, I. K.; Minnebaev, K. F.; Zykova, E. Yu.; Ivanenko, I. P.; Yurasova, V. E.

    2014-03-01

    Secondary ion emission from silicon and graphite single crystals bombarded by argon ions with energies E 0 varied from 1 to 10 keV at various angles of incidence α has been studied. The evolution of the energy spectra of C+ and Si+ secondary ions has been traced in which the positions of maxima ( E max) shift toward higher secondary-ion energies E 1 with increasing polar emission angle θ (measured from the normal to the sample surface). The opposite trend has been observed for ions emitted from single crystals heated to several hundred degrees Centigrade; the E max values initially remain unchanged and then shift toward lower energies E 1 with increasing angle θ. It is established that the magnitude and position of a peak in the energy spectrum of secondary C+ ions is virtually independent of E 0, angle α, and the surface relief of the sample (in the E 0 and α intervals studied). Unusual oscillating energy distributions are discussed, which have been observed for secondary ions emitted from silicon (111) and layered graphite (0001) faces. Numerical simulations of secondary ion sputtering and charge exchange have been performed. A comparison of the measured and calculated data for graphite crystals has shown that C+ ions are formed as a result of charge exchange between secondary ions and bombarding Ar+ ions, which takes place both outside and inside the target. This substantially differs from the ion sputtering process in metals and must be taken into account when analyzing secondary ion emission mechanisms and in practical applications of secondary-ion mass spectrometry.

  18. Photonic guiding structures in lithium niobate crystals produced by energetic ion beams

    NASA Astrophysics Data System (ADS)

    Chen, Feng

    2009-10-01

    A range of ion beam techniques have been used to fabricate a variety of photonic guiding structures in the well-known lithium niobate (LiNbO3 or LN) crystals that are of great importance in integrated photonics/optics. This paper reviews the up-to-date research progress of ion-beam-processed LiNbO3 photonic structures and reports on their fabrication, characterization, and applications. Ion beams are being used with this material in a wide range of techniques, as exemplified by the following examples. Ion beam milling/etching can remove the selected surface regions of LiNbO3 crystals via the sputtering effects. Ion implantation and swift ion irradiation can form optical waveguide structures by modifying the surface refractive indices of the LiNbO3 wafers. Crystal ion slicing has been used to obtain bulk-quality LiNbO3 single-crystalline thin films or membranes by exfoliating the implanted layer from the original substrate. Focused ion beams can either generate small structures of micron or submicron dimensions, to realize photonic bandgap crystals in LiNbO3, or directly write surface waveguides or other guiding devices in the crystal. Ion beam-enhanced etching has been extensively applied for micro- or nanostructuring of LiNbO3 surfaces. Methods developed to fabricate a range of photonic guiding structures in LiNbO3 are introduced. Modifications of LiNbO3 through the use of various energetic ion beams, including changes in refractive index and properties related to the photonic guiding structures as well as to the materials (i.e., electro-optic, nonlinear optic, luminescent, and photorefractive features), are overviewed in detail. The application of these LiNbO3 photonic guiding structures in both micro- and nanophotonics are briefly summarized.

  19. Linear and cubic response to the initial eccentricity in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Noronha-Hostler, Jacquelyn; Yan, Li; Gardim, Fernando G.; Ollitrault, Jean-Yves

    2016-01-01

    We study the relation between elliptic flow, v2, and the initial eccentricity, ɛ2, in heavy-ion collisions, using hydrodynamic simulations. Significant deviations from linear eccentricity scaling are seen in more peripheral collisions. We identify the mechanism responsible for these deviations as a cubic response, which we argue is a generic property of the hydrodynamic response to the initial density profile. The cubic response increases elliptic flow fluctuations, thereby improving agreement of initial condition models with experimental data.

  20. Fabrication of specimens of metamorphic magnetite crystals for field ion microscopy and atom probe microanalysis.

    PubMed

    Kuhlman, K R; Martens, R L; Kelly, T F; Evans, N D; Miller, M K

    2001-10-01

    Field ion specimens have been successfully fabricated from samples of metamorphic magnetite crystals (Fe3O4) extracted from a polymetamorphosed, granulite-facies marble with the use of a focused ion beam. These magnetite crystals contain nanometer-scale, disk-shaped inclusions making this magnetite particularly attractive for investigating the capabilities of atom probe field ion microscopy (APFIM) for geological materials. Field ion microscope images of these magnetite crystals were obtained in which the observed size and morphology of the precipitates agree with previous results. Samples were analyzed in the energy compensated optical position-sensitive atom probe. Mass spectra were obtained in which peaks for singly ionized 16O, 56Fe and 56FeO and doubly ionized 54Fe, 56Fe and 57Fe peaks were fully resolved. Manganese and aluminum were observed in a limited analysis of a precipitate in an energy compensated position sensitive atom probe. PMID:11770743

  1. Low-temperature nanodoping of protonated LiNbO3 crystals by univalent ions

    NASA Astrophysics Data System (ADS)

    Borodin, Yu. V.

    2015-01-01

    In the nanocomposite model developed here, crystals are treated as subordinate aggregate of pro- ton-selected structural elements, their blocks, and proton-containing quantum sublattices with preferred transport effects separating them. The formation of stratified reversible hexagonal structures is accompanied with protonation and formation of a dense network of H-bonds ensuring the nanocomposite properties. Nanodoping with H+ ions occurs during processing of crystals and glasses in melts as well as in aqueous solutions of Ag, Tl, Rb, and Cs salts. The isotope exchange H+ ↔ D+ and ion exchange H+ ↔ M+ lead to nanodoping of protonated materials with D+ and M+ ions. This is manifested especially clearly in Li-depleted nonequilibrium LiNbO3 and LiTaO3 crystals. Low-temperature proton-ion nanodoping over superlattices is a basically new approach to analysis of the structure and properties of extremely nonequilibrium materials.

  2. Triple quadrupole linear ion trap mass spectrometer for the analysis of small molecules and macromolecules.

    PubMed

    Hopfgartner, Gérard; Varesio, Emmanuel; Tschäppät, Viviane; Grivet, Chantal; Bourgogne, Emmanuel; Leuthold, Luc Alexis

    2004-08-01

    Recently, linear ion traps (LITs) have been combined with quadrupole (Q), time-of-flight (TOF) and Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS). LITs can be used either as ion accumulation devices or as commercially available, stand-alone mass spectrometers with MSn capabilities. The combination of triple quadrupole MS with LIT technology in the form of an instrument of configuration QqLIT, using axial ejection, is particularly interesting, because this instrument retains the classical triple quadrupole scan functions such as selected reaction monitoring (SRM), product ion (PI), neutral loss (NL) and precursor ion (PC) while also providing access to sensitive ion trap experiments. For small molecules, quantitative and qualitative analysis can be performed using the same instrument. In addition, for peptide analysis, the enhanced multiply charged (EMC) scan allows an increase in selectivity, while the time-delayed fragmentation (TDF) scan provides additional structural information. Various methods of operating the hybrid instrument are described for the case of the commercial Q TRAP (AB/MDS Sciex) and applications to drug metabolism analysis, quantitative confirmatory analysis, peptides analysis and automated nanoelectrospray (ESI-chip-MS) analysis are discussed. PMID:15329837

  3. Linear and nonlinear physics of the magnetoacoustic cyclotron instability of fusion-born ions in relation to ion cyclotron emission

    SciTech Connect

    Carbajal, L. Cook, J. W. S.; Dendy, R. O.; Chapman, S. C.

    2014-01-15

    The magnetoacoustic cyclotron instability (MCI) probably underlies observations of ion cyclotron emission (ICE) from energetic ion populations in tokamak plasmas, including fusion-born alpha-particles in JET and TFTR [Dendy et al., Nucl. Fusion 35, 1733 (1995)]. ICE is a potential diagnostic for lost alpha-particles in ITER; furthermore, the MCI is representative of a class of collective instabilities, which may result in the partial channelling of the free energy of energetic ions into radiation, and away from collisional heating of the plasma. Deep understanding of the MCI is thus of substantial practical interest for fusion, and the hybrid approximation for the plasma, where ions are treated as particles and electrons as a neutralising massless fluid, offers an attractive way forward. The hybrid simulations presented here access MCI physics that arises on timescales longer than can be addressed by fully kinetic particle-in-cell simulations and by analytical linear theory, which the present simulations largely corroborate. Our results go further than previous studies by entering into the nonlinear stage of the MCI, which shows novel features. These include stronger drive at low cyclotron harmonics, the re-energisation of the alpha-particle population, self-modulation of the phase shift between the electrostatic and electromagnetic components, and coupling between low and high frequency modes of the excited electromagnetic field.

  4. Linear and nonlinear physics of the magnetoacoustic cyclotron instability of fusion-born ions in relation to ion cyclotron emission

    NASA Astrophysics Data System (ADS)

    Carbajal, L.; Dendy, R. O.; Chapman, S. C.; Cook, J. W. S.

    2014-01-01

    The magnetoacoustic cyclotron instability (MCI) probably underlies observations of ion cyclotron emission (ICE) from energetic ion populations in tokamak plasmas, including fusion-born alpha-particles in JET and TFTR [Dendy et al., Nucl. Fusion 35, 1733 (1995)]. ICE is a potential diagnostic for lost alpha-particles in ITER; furthermore, the MCI is representative of a class of collective instabilities, which may result in the partial channelling of the free energy of energetic ions into radiation, and away from collisional heating of the plasma. Deep understanding of the MCI is thus of substantial practical interest for fusion, and the hybrid approximation for the plasma, where ions are treated as particles and electrons as a neutralising massless fluid, offers an attractive way forward. The hybrid simulations presented here access MCI physics that arises on timescales longer than can be addressed by fully kinetic particle-in-cell simulations and by analytical linear theory, which the present simulations largely corroborate. Our results go further than previous studies by entering into the nonlinear stage of the MCI, which shows novel features. These include stronger drive at low cyclotron harmonics, the re-energisation of the alpha-particle population, self-modulation of the phase shift between the electrostatic and electromagnetic components, and coupling between low and high frequency modes of the excited electromagnetic field.

  5. Linear Ion Traps in Space: The Mars Organic Molecule Analyzer (MOMA) Instrument and Beyond

    NASA Astrophysics Data System (ADS)

    Arevalo, Ricardo; Brinckerhoff, William; Mahaffy, Paul; van Amerom, Friso; Danell, Ryan; Pinnick, Veronica; Li, Xiang; Hovmand, Lars; Getty, Stephanie; Grubisic, Andrej; Goesmann, Fred; Cottin, Hervé

    2015-11-01

    Historically, quadrupole mass spectrometer (QMS) instruments have been used to explore a wide survey of planetary targets in our solar system, from Venus (Pioneer Venus) to Saturn (Cassini-Huygens). However, linear ion trap (LIT) mass spectrometers have found a niche as smaller, versatile alternatives to traditional quadrupole analyzers.The core astrobiological experiment of ESA’s ExoMars Program is the Mars Organic Molecule Analyzer (MOMA) onboard the ExoMars 2018 rover. The MOMA instrument is centered on a linear (or 2-D) ion trap mass spectrometer. As opposed to 3-D traps, LIT-based instruments accommodate two symmetrical ion injection pathways, enabling two complementary ion sources to be used. In the case of MOMA, these two analytical approaches are laser desorption mass spectrometry (LDMS) at Mars ambient pressures, and traditional gas chromatography mass spectrometry (GCMS). The LIT analyzer employed by MOMA also offers: higher ion capacity compared to a 3-D trap of the same volume; redundant detection subassemblies for extended lifetime; and, a link to heritage QMS designs and assembly logistics. The MOMA engineering test unit (ETU) has demonstrated the detection of organics in the presence of wt.%-levels of perchlorate, effective ion enhancement via stored waveform inverse Fourier transform (SWIFT), and derivation of structural information through tandem mass spectrometry (MS/MS).A more progressive linear ion trap mass spectrometer (LITMS), funded by the NASA ROSES MatISSE Program, is being developed at NASA GSFC and promises to augment the capabilities of the MOMA instrument by way of: an expanded mass range (i.e., 20 - 2000 Da); detection of both positive and negative ions; spatially resolved (<1 mm) characterization of individual rock core layers; and, evolved gas analysis and GCMS with pyrolysis up to 1300° C (enabling breakdown of refractory phases). The Advanced Resolution Organic Molecule Analyzer (AROMA) instrument, being developed through NASA

  6. Linear relationships between acidity and stability in mono- and hexahydrated metal ions: a computational study

    NASA Astrophysics Data System (ADS)

    George, Philip; Glusker, Jenny P.; Trachtman, Mendel; Bock, Charles W.

    2002-01-01

    Linear relationships have been established between the dissociation enthalpies of the monohydrates of Li +, Na +, K +, Be 2+, Mg 2-, Ca 2+, Mn 2+, Fe 2+, Co 2+, Ni 2+, Cu 2+, Zn 2+, Al 3+, Sc 3+, Ti 3+, V 3+, Mn 3+, Fe 3+ and Ga 3+ calculated at the MP2(FULL)/6-311++G**//MP2(FULL)/6-311++G** level, the hexahydrates of Na +, K +, Mg 2+, Ca 2+, Mn 2+, Zn 2+, Al 3+, Sc 3+, Fe 3+ and Ga 3+ calculated at the MP2(FULL)/6-311++G**//HF/6-311++G** level, and experimentally reported p Ka values for the first ionization of the corresponding aqua-ions. In contrast to the results of Chang and Wang [Chem. Phys. Lett. 286 (1998) 46], we find that the 3+ ion hexahydrates are more (not less) stable than the 2+ ion hexahydrates.

  7. Experimental study on dipole motion of an ion plasma confined in a linear Paul trap

    NASA Astrophysics Data System (ADS)

    Ito, K.; Okano, T.; Moriya, K.; Fukushima, K.; Higaki, H.; Okamoto, H.

    2015-11-01

    The compact non-neutral plasma trap systems named "S-POD" have been developed at Hiroshima University as an experimental simulator of beam dynamics. S-POD is based either on a linear Paul trap or on a Penning trap and can approximately reproduce the collective motion of a relativistic charged-particle beam observed in the center-of-mass frame. We here employ the Paul trap system to investigate the behavior of an ion plasma near a dipole resonance. A simple method is proposed to calibrate the data of secular frequency measurements by using the dipole instability condition. We also show that the transverse density profile of an ion plasma in the trap can be estimated from the time evolution of ion losses caused by the resonance.

  8. Linear and nonlinear ion-acoustic waves in nonrelativistic quantum plasmas with arbitrary degeneracy

    NASA Astrophysics Data System (ADS)

    Haas, Fernando; Mahmood, Shahzad

    2015-11-01

    Linear and nonlinear ion-acoustic waves are studied in a fluid model for nonrelativistic, unmagnetized quantum plasma with electrons with an arbitrary degeneracy degree. The equation of state for electrons follows from a local Fermi-Dirac distribution function and applies equally well both to fully degenerate and classical, nondegenerate limits. Ions are assumed to be cold. Quantum diffraction effects through the Bohm potential are also taken into account. A general coupling parameter valid for dilute and dense plasmas is proposed. The linear dispersion relation of the ion-acoustic waves is obtained and the ion-acoustic speed is discussed for the limiting cases of extremely dense or dilute systems. In the long-wavelength limit, the results agree with quantum kinetic theory. Using the reductive perturbation method, the appropriate Korteweg-de Vries equation for weakly nonlinear solutions is obtained and the corresponding soliton propagation is analyzed. It is found that soliton hump and dip structures are formed depending on the value of the quantum parameter for the degenerate electrons, which affect the phase velocities in the dispersive medium.

  9. Linearly polarized light with axial symmetry generated by liquid-crystal polarization converters

    NASA Astrophysics Data System (ADS)

    Stalder, M.; Schadt, M.

    1996-12-01

    Novel liquid-crystal devices are described that generate linearly polarized light with axial symmetry; the beam propagation axis is the symmetry axis. Such light fields can be characterized by a polarization order number P . For example, P=1 fields represent radially or azimuthally polarized light. The reorientation of the polarization orientation in these polarization converters is due to the twisted nematic effect and the effect of lambda /2 wave plates. A single polarization converter can generate fields of orders 1 and 2. It is shown that one can in principle generate fields of any integral order P by cascading such elements. Devices that generate P=1 fields are achromatic and can be used as polarization axis finders or as versatile tools for studying birefringent or polarizing materials.

  10. Crystal structure of Sr2CdPt2 containing linear platinum chains

    PubMed Central

    Nawawi, Effendi; Gulo, Fakhili; Köhler, Jürgen

    2016-01-01

    The ternary inter­metallic title phase, distrontium cadmium diplatinum, was prepared from stoichiometric amounts of the elements at 1123 K for one day. The crystal structure adopts the ortho­rhom­bic Ca2GaCu2 structure type in space group Immm. Its main features are characterized by linear (Pt—Pt⋯Pt—Pt)n chains that are aligned along [010] and condensed through cadmium atoms forming Cd-centred Pt2Cd2/2 rectangles to build up sheets parallel to (001). These sheets are connected to each other via alternating (001) sheets of strontium atoms along [001]. The strontium sheets consists of corrugated Sr4 units that are condensed to each other through edge-sharing parallel to [100]. PMID:26958374

  11. Crystal structure of Sr2CdPt2 containing linear platinum chains.

    PubMed

    Nawawi, Effendi; Gulo, Fakhili; Köhler, Jürgen

    2016-02-01

    The ternary inter-metallic title phase, distrontium cadmium diplatinum, was prepared from stoichiometric amounts of the elements at 1123 K for one day. The crystal structure adopts the ortho-rhom-bic Ca2GaCu2 structure type in space group Immm. Its main features are characterized by linear (Pt-Pt⋯Pt-Pt) n chains that are aligned along [010] and condensed through cadmium atoms forming Cd-centred Pt2Cd2/2 rectangles to build up sheets parallel to (001). These sheets are connected to each other via alternating (001) sheets of strontium atoms along [001]. The strontium sheets consists of corrugated Sr4 units that are condensed to each other through edge-sharing parallel to [100]. PMID:26958374

  12. A high quality factor photonic crystal channel-drop filter with a linear gradient microcavity

    NASA Astrophysics Data System (ADS)

    Li, Chuan-qi; Fan, Qing-bin; Lu, Ye; Luo, De-jun; Kong, Yi-bu; Zhang, Dong-chuang

    2015-05-01

    We design a channel-drop filter (CDF) with a linear gradient microcavity in a two-dimensional (2D) photonic crystal (PC). The model of three-port CDF with reflector is used to achieve high quality factor (Q-factor) and 100% channel-drop efficiency. The research indicates that adjusting the distance between reference plane and reflector can simultaneously influence the Q-factor due to coupling to a bus waveguide and the phase retardation occurring in the round trip between a microcavity and a reflector. The calculation results of 2D finite-difference time-domain (FDTD) method show that the designed filter can achieve the drop efficiency of 96.7% and ultra-high Q-factor with an ultra-small modal volume.

  13. Highly non-linear solid core photonic crystal fiber with one nano hole

    NASA Astrophysics Data System (ADS)

    Gangwar, Rahul Kumar; Bhardwaj, Vanita; Singh, Vinod Kumar

    2015-08-01

    The numerical study of newly designed solid core photonic crystal fiber (SCPCF) having three hexagonal air hole rings in cladding region and one small nano hole at the center are presented. By using full vectorial finite element method (FV-FEM), we analyses the optical properties like effective area, nonlinearity and confinement loss of the proposed PCF. Results show that the change in core diameter controls the effective area, nonlinearity and confinement loss. A low effective area (3.34 µm2), high nonlinearity (36.34 W-1km-1) and low confinement loss (0.00106 dB/km) are achieved at the communication wavelength 1.55 µm for the SCPCF having core air hole diameter 0.10 µm, cladding air holes diameter 1.00 µm and pitch 2.50 µm. This type of PCF is very useful in non-linear applications such as supercontinuum generation, four wave mixing, second harmonic generation etc.

  14. Fabrication and Characterization of Linear Terahertz Detector Arrays Based on Lithium Tantalate Crystal

    NASA Astrophysics Data System (ADS)

    Li, Weizhi; Wang, Jun; Gou, Jun; Huang, Zehua; Jiang, Yadong

    2015-01-01

    Two samples of 30-pixel linear terahertz detector arrays (TDAs) were fabricated based on lithium tantalate (LT) crystals. Pixel readout circuit (ROC) was designed to extract the weak current signal of TDAs. A test platform was established for performance evaluation of TDA+ROC components. By using a 2.52THz laser as radiation source, the test results reveal that average voltage responsivities of the components were larger than 7000V/W and non-uniformity no more than 2.1%. Average noise equivalent power ( NEP) of one sample was measured to be 1.5×10-9 W/Hz1/2, which is low enough and desirable for high performance THz detector.

  15. Generalized Jeans' Escape of Pick-Up Ions in Quasi-Linear Relaxation

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Khazanov, G. V.

    2011-01-01

    Jeans escape is a well-validated formulation of upper atmospheric escape that we have generalized to estimate plasma escape from ionospheres. It involves the computation of the parts of particle velocity space that are unbound by the gravitational potential at the exobase, followed by a calculation of the flux carried by such unbound particles as they escape from the potential well. To generalize this approach for ions, we superposed an electrostatic ambipolar potential and a centrifugal potential, for motions across and along a divergent magnetic field. We then considered how the presence of superthermal electrons, produced by precipitating auroral primary electrons, controls the ambipolar potential. We also showed that the centrifugal potential plays a small role in controlling the mass escape flux from the terrestrial ionosphere. We then applied the transverse ion velocity distribution produced when ions, picked up by supersonic (i.e., auroral) ionospheric convection, relax via quasi-linear diffusion, as estimated for cometary comas [1]. The results provide a theoretical basis for observed ion escape response to electromagnetic and kinetic energy sources. They also suggest that super-sonic but sub-Alfvenic flow, with ion pick-up, is a unique and important regime of ion-neutral coupling, in which plasma wave-particle interactions are driven by ion-neutral collisions at densities for which the collision frequency falls near or below the gyro-frequency. As another possible illustration of this process, the heliopause ribbon discovered by the IBEX mission involves interactions between the solar wind ions and the interstellar neutral gas, in a regime that may be analogous [2].

  16. Piezoelectric single crystal and magnetostrictive Metglas composites: Linear and nonlinear magnetoelectric coupling

    NASA Astrophysics Data System (ADS)

    Wang, Yaojin; Finkel, P.; Li, Jiefang; Viehland, D.

    2014-04-01

    Both the linear (αV) and nonlinear (αV,n) magnetoelectric coefficients were systemically studied in laminated composites of Metglas and [001]-orientated piezoelectric single crystals of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) and Mn-doped PMN-PT. The coefficients were close in value in both cases at quasistatic mode (i.e., 3.8 V/Oe relative to 3.5 V/Oe) and were enhanced by factors of ×18 (Metglas/PMN-PT) and ×32 (Metglas/Mn-doped PMN-PT) at the electromechanical resonance (EMR). The use of Mn-doped PMN-PT crystals results in a higher gain factor due to a larger mechanical quality factor (i.e., 20.9 relative to 40.6). Accordingly, both types of laminates had similar values of αV,n when modulated at 1 kHz, but Mn-doped PMN-PT ones had a higher value when modulated at the EMR.

  17. Growth and characterization of ADP single crystals doped with alkali and alkaline metal ions

    NASA Astrophysics Data System (ADS)

    Kavya, H.; Bhavyashree, M.; Kumari, R. Ananda

    2016-05-01

    Pure and KBr, KI, MgCl2 & LiCl added ammonium dihydrogen orthophosphate (ADP) single crystals have been grown at room temperature by the slow evaporation method. The grown crystals have been subjected to powder XRD, FTIR, UV-Vis, and SHG studies. The crystallinity and the functional groups are confirmed by powder XRD and FTIR spectroscopy. Good transparency in the entire visible region which is an essential requirement for a nonlinear optical crystal is observed for the grown crystals. Results of the non-linear optical measurements indicate the enhancement of second harmonic generation efficiency due to the dopants and show the suitability of the ingot for nonlinear optical application

  18. Impact of Protein-Metal Ion Interactions on the Crystallization of Silk Fibroin Protein

    NASA Astrophysics Data System (ADS)

    Hu, Xiao; Lu, Qiang; Kaplan, David; Cebe, Peggy

    2009-03-01

    Proteins can easily form bonds with a variety of metal ions, which provides many unique biological functions for the protein structures, and therefore controls the overall structural transformation of proteins. We use advanced thermal analysis methods such as temperature modulated differential scanning calorimetry and quasi-isothermal TMDSC, combined with Fourier transform infrared spectroscopy, and scanning electron microscopy, to investigate the protein-metallic ion interactions in Bombyx mori silk fibroin proteins. Silk samples were mixed with different metal ions (Ca^2+, K^+, Ma^2+, Na^+, Cu^2+, Mn^2+) with different mass ratios, and compared with the physical conditions in the silkworm gland. Results show that all metallic ions can directly affect the crystallization behavior and glass transition of silk fibroin. However, different ions tend to have different structural impact, including their role as plasticizer or anti-plasticizer. Detailed studies reveal important information allowing us better to understand the natural silk spinning and crystallization process.

  19. Studies on L-citrulline doped potassium dihydrogen phosphate- A non linear crystal with significant nonlinear properties

    NASA Astrophysics Data System (ADS)

    Sreevalsa, V. G.; Jayalekshmi, S.

    2014-01-01

    Potassium Dihydrogen Phosphate (KDP) single crystal is considered as one of the best representative of nonlinear optical crystals. Recently, amino acids having excellent nonlinear optical characteristics are being investigated as prospective dopants to improve the non linear optical characteristics of KDP. The present work is an attempt in this direction and L citrulline, one of the non essential amino acids showing good non linear optical characteristics is used as the dopant for KDP. Good quality crystals of L-citrulline doped KDP crystals were grown by slow evaporation technique. From the powder X-ray diffraction studies of doped KDP crystal, the structure of the doped crystals was determined by direct method and refined by Pawley method employing Topaz version program using the single crystal X-ray data for pure KDP. The lattice parameters for L citrulline doped KDP are a=7.467A0, b=7.467 A0, c=6.977 A0. The crystal falls into the tetragonal crystal system with space group I42 d. The presence of carbon and oxygen, which are primary components of amino acids, in the EDAX spectrum confirms the effectiveness of doping. The absorption spectra of the doped samples show that the crystals are transparent in the entire visible region. The second harmonic generation efficiency of the doped samples was determined by Kurtz powder technique using the Q-switched Nd:YAG laser beam and is found to be 2.2 times that of KDP. The nonlinear optical properties can be well studied by the open aperture Z scan technique. The open aperture curve exhibits a normalized transmittance valley. The nonlinear absorption coefficient β is obtained by theoretical fitting for two photon absorption. It is inferred that doping KDP with L citrulline has enhanced the nonlinearity considerably. This obviously suggests the potentiality of the crystal as an optical power limiter and also for various optical device applications.

  20. Studies on L-citrulline doped potassium dihydrogen phosphate- A non linear crystal with significant nonlinear properties

    SciTech Connect

    Sreevalsa, V. G. E-mail: jayalekshmi@cusat.ac.in; Jayalekshmi, S. E-mail: jayalekshmi@cusat.ac.in

    2014-01-28

    Potassium Dihydrogen Phosphate (KDP) single crystal is considered as one of the best representative of nonlinear optical crystals. Recently, amino acids having excellent nonlinear optical characteristics are being investigated as prospective dopants to improve the non linear optical characteristics of KDP. The present work is an attempt in this direction and L citrulline, one of the non essential amino acids showing good non linear optical characteristics is used as the dopant for KDP. Good quality crystals of L-citrulline doped KDP crystals were grown by slow evaporation technique. From the powder X-ray diffraction studies of doped KDP crystal, the structure of the doped crystals was determined by direct method and refined by Pawley method employing Topaz version program using the single crystal X-ray data for pure KDP. The lattice parameters for L citrulline doped KDP are a=7.467A{sup 0}, b=7.467 A{sup 0}, c=6.977 A{sup 0}. The crystal falls into the tetragonal crystal system with space group I42 d. The presence of carbon and oxygen, which are primary components of amino acids, in the EDAX spectrum confirms the effectiveness of doping. The absorption spectra of the doped samples show that the crystals are transparent in the entire visible region. The second harmonic generation efficiency of the doped samples was determined by Kurtz powder technique using the Q-switched Nd:YAG laser beam and is found to be 2.2 times that of KDP. The nonlinear optical properties can be well studied by the open aperture Z scan technique. The open aperture curve exhibits a normalized transmittance valley. The nonlinear absorption coefficient β is obtained by theoretical fitting for two photon absorption. It is inferred that doping KDP with L citrulline has enhanced the nonlinearity considerably. This obviously suggests the potentiality of the crystal as an optical power limiter and also for various optical device applications.

  1. Improving Brush Polymer Infrared One-Dimensional Photonic Crystals via Linear Polymer Additives

    SciTech Connect

    Macfarlane, Robert J.; Kim, Bongkeun; Lee, Byeongdu; Weitekamp, Raymond A.; Bates, Christopher M.; Lee, Siu Fung; Chang, Alice B.; Delaney, Kris T.; Fredrickson, Glen H.; Atwater, Harry A.; Grubbs, Robert H.

    2014-12-17

    Brush block copolymers (BBCPs) enable the rapid fabrication of self-assembled one-dimensional photonic crystals with photonic band gaps that are tunable in the UV-vis-IR, where the peak wavelength of reflection scales with the molecular weight of the BBCPs. Due to the difficulty in synthesizing very large BBCPs, the fidelity of the assembled lamellar nanostructures drastically erodes as the domains become large enough to reflect IR light, severely limiting their performance as optical filters. To overcome this challenge, short linear homopolymers are used to swell the arrays to ~180% of the initial domain spacing, allowing for photonic band gaps up to~1410 nm without significant opacity in the visible, demonstrating improved ordering of the arrays. Additionally, blending BBCPs with random copolymers enables functional groups to be incorporated into the BBCP array without attaching them directly to the BBCPs. The addition of short linear polymers to the BBCP arrays thus offers a facile means of improving the self-assembly and optical properties of these materials, as well as adding a route to achieving films with greater functionality and tailorability, without the need to develop or optimize the processing conditions for each new brush polymer synthesized.

  2. H+ ion implantation on L-arginine monohydrobromide monohydrate single crystal for tuning electro-optical properties

    NASA Astrophysics Data System (ADS)

    Sangeetha, K.; Babu, R. Ramesh; Kumar, Praveen; Bhagavannarayana, G.; Ramamurthi, K.

    2011-03-01

    A nonlinear optical single crystal, l-arginine monohydrobromide monohydrate (LAHBr), has been implanted with 100 keV H+ ions at different ion fluences ranging from 1012 to 1015 ions/cm2 to study the property changes after implantation. Crystalline perfection of the pristine and implanted LAHBr crystals was analyzed using high-resolution X-ray diffraction. The refractive index, birefringence, mechanical stability, dielectric constant and optical absorption bands induced by color centers of the implanted crystals were studied at different ion fluences and compared with pristine LAHBr single crystals.

  3. Homogeneous alignment of nematic liquid crystals by ion beam etched surfaces

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.; Mahmood, R.; Johnson, D. L.

    1979-01-01

    A wide range of the ion beam etch parameters are capable of producing uniform homogeneous alignment of nematic liquid crystals on SiO2 films. The alignment surfaces were generated by obliquely incident argon ions; a smaller range of ion beam parameters was also investigated with ZrO2 films and found suitable for homogeneous alignment. Extinction ratios were very high, and twist and tilt-bias angles were very small. The SEM results indicate a parallel oriented surface structure on the ion beam etched surfaces which may determine alignment.

  4. Electromagnetic hot ion beam instabilities - Quasi-linear theory and simulation

    NASA Technical Reports Server (NTRS)

    Rogers, B.; Gary, S. P.; Winske, D.

    1985-01-01

    This paper considers the quasi-linear theory of the right- and left-hand resonant electromagnetic instabilities driven by a hot ion beam streaming parallel to a magnetic field in a homogeneous Vlasov plasma. Using the single-mode approximation, the time evolutions of important parameters are obtained to show that for the range of parameters considered, reduction of the beam speed and formation of temperature anisotropies are the most significant factors in the quasi-linear stabilization process. Combining both instabilities in a quasi-linear study is found to produce a roughly equal mixture of both polarizations and relatively isotropic conditions for tenuous beam densities and low initial beam drift speeds. Computer simulations are used to compare with the quasi-linear results. The simulations justify the single-mode assumption, verify that quasi-linear changes are the means of saturation for the parameter range of concern, and check the nonlinear evolution of the system when both modes are present.

  5. Note: A novel design of a microwave feed for a microwave frequency standard with a linear ion trap

    SciTech Connect

    Zhang, J. W. Miao, K.; Wang, S. G.; Wang, Z. B.

    2014-07-15

    Linear ion traps are important tools in many applications, particularly in mass spectrum analyzers and frequency standards. Here a novel design of a microwave feed integrated into one electrode of a linear quadrupole ion trap is demonstrated for the application of a microwave frequency standard based on cadmium ions. The mechanical structure of the microwave feed is compact and easy to build. The ion trap integrated with this microwave feed is successfully applied to measure the hyperfine splitting of the ground state of {sup 113}Cd{sup +}, thus demonstrating the practicality and reliability of the microwave feed.

  6. Crystal orientation mapping via ion channeling: An alternative to EBSD.

    PubMed

    Langlois, C; Douillard, T; Yuan, H; Blanchard, N P; Descamps-Mandine, A; Van de Moortèle, B; Rigotti, C; Epicier, T

    2015-10-01

    A new method, which we name ion CHanneling ORientation Determination (iCHORD), is proposed to obtain orientation maps on polycrystals via ion channeling. The iChord method exploits the dependence between grain orientation and ion beam induced secondary electron image contrast. At each position of the region of interest, intensity profiles are obtained from a series of images acquired with different orientations with respect to the ion beam. The profiles are then compared to a database of theoretical profiles of known orientation. The Euler triplet associated to the most similar theoretical profile gives the orientation at that position. The proof-of-concept is obtained on a titanium nitride sample. The potentialities of iCHORD as an alternative to EBSD are then discussed. PMID:26094201

  7. Ion Density Analysis of Single-Stranded DNA in Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Iwabata, Kazuki; Seki, Yasutaka; Toizumi, Ryota; Shimada, Yuki; Furue, Hirokazu; Sakaguchi, Kengo

    2013-09-01

    With the widespread use of liquid crystals (LCs) in liquid crystal displays, we have looked into the application of liquid crystals in biotechnology. The purpose of the study described here is to investigate the physical properties of DNA using LCs. Synthetic oligonucleotide molecules were dispersed in MLC6884, the sample injected into antiparallel cells, and the amount of mobile ions was measured. The LC cell doped with oligonucleotide molecules showed a sequence-dependent, specific correlation between oligonucleotide concentration and the amount of mobile ions in the LC cells. In the framework of the Stokes model and polyacrylamide gel electrophoresis (PAGE) analysis, we speculate that this result arises from the difference in ion mobility, which is caused by the shape of the oligonucleotide molecule in the LC.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  9. Electrochemical Ion-Exchange Regeneration and Fluidized Bed Crystallization for Zero-Liquid-Discharge Water Softening.

    PubMed

    Chen, Yingying; Davis, Jake R; Nguyen, Chi H; Baygents, James C; Farrell, James

    2016-06-01

    This research investigated the use of an electrochemical system for regenerating ion-exchange media and for promoting the crystallization of hardness minerals in a fluidized bed crystallization reactor (FBCR). The closed-loop process eliminates the creation of waste brine solutions that are normally produced when regenerating ion-exchange media. A bipolar membrane electrodialysis stack was used to generate acids and bases from 100 mM salt solutions. The acid was used to regenerate weak acid cation (WAC) ion-exchange media used for water softening. The base solutions were used to absorb CO2 gas and to provide a source of alkalinity for removing noncarbonate hardness by WAC media operated in H(+) form. The base solutions were also used to promote the crystallization of CaCO3 and Mg(OH)2 in a FBCR. The overall process removes hardness ions from the water being softened and replaces them with H(+) ions, slightly decreasing the pH value of the softened water. The current utilization efficiency for acid and base production was ∼75% over the operational range of interest, and the energy costs for producing acids and bases were an order of magnitude lower than the costs for purchasing acid and base in bulk quantities. Ion balances indicate that the closed-loop system will accumulate SO4(2-), Cl(-), and alkali metal ions. Acid and base balances indicate that for a typical water, small amounts of base will be accumulated. PMID:27161852

  10. Surface morphological instability of silicon (100) crystals under microwave ion physical etching

    NASA Astrophysics Data System (ADS)

    Yafarov, R. K.; Shanygin, V. Ya.

    2016-02-01

    This paper presents the results of studies of the dynamics of relaxation modification of the morphological characteristics of atomically clean surfaces of silicon (100) crystals with different types of conductivity after microwave ion physical etching in an argon atmosphere. For the first time, the effect of the electronic properties on the morphological characteristics and the surface free energy of silicon crystals is experimentally shown and proven by physicochemical methods.

  11. Resonant coherent excitation of hydrogen-like ions planar channeled in a crystal; Transition into the first excited state

    NASA Astrophysics Data System (ADS)

    Babaev, A.; Pivovarov, Yu. L.

    2012-03-01

    observed in the outgoing beam behind the crystal. To get the probabilities for the ion to be in the ground state or in the first excited state, or to be ionized, the Schrödinger equation is solved for the electron of ion. The numerical solving of the Schrödinger equation is carried out taking into account the fine structure of electronic energy levels, the Stark effect due to the influence of the crystal electric field on electronic energy levels and the ionization of ion due to the collisions with crystal electrons. Solution method: The wave function of the electron of ion is the superposition of the wave functions of stationary states with time-dependent coefficients. These stationary wave functions and corresponding energies are defined from the stationary Schrödinger equation. The equation is reduced to the problem of the eigen values and vectors of Hermitian matrix. The corresponding matrix equation is considered as the linear equation system. Then the time-dependent coefficients of the electron wave function are defined from the Schrödinger equation, with a time-periodic crystal field. The time-periodic field is responsible for the transitions between the stationary states. The final time-dependent Schrödinger equation represents the matrix equation which has been solved by means of the QR-algorithm. Restrictions: As expected the program gives the correct results for relativistic hydrogen-like ions with the kinetic energies up to 1 GeV/u and at the crystal thicknesses of 1-100 μm. The restrictions are: first, the program might give inadequate results, when the ion kinetic energy is too large (>10 GeV/u); second, the unaccounted physical factors may be significant at specific conditions. For example, the spontaneous emission by exited highly charged ions, as well as both energy and angular spread of the incident beam, could lead to additional broadening of the resonance. The medium polarization by the electric field of ion can influence the electronic energy

  12. Liquid crystal surface alignments by using ion beam sputtered magnetic thin films

    SciTech Connect

    Wu, H.-Y.; Pan, R.-P.

    2007-08-13

    A method for liquid crystal surface alignment by using a one-step, ion beam bombardment of the glass substrates is demonstrated. Precoating by polyimide is not necessary. The authors show that the homeotropic alignment is achieved due to orientation of the diamagnetic nematogenic molecules by the magnetic field from the {gamma}-Fe{sub 2}O{sub 3} ferrimagnetic thin films created on the substrates by ion beam bombardment. The film exhibits a high Curie temperature well above 300 K and a compensation temperature which is the typical feature of ferrimagnetism. This is a simple, noncontact, and reliable alignment method for liquid crystal devices.

  13. Determination of Na acceptor level in Na+ ion-implanted ZnO single crystal

    NASA Astrophysics Data System (ADS)

    Wang, Zheng; Liu, Huibin; He, Haiping; Huang, Jingyun; Chen, Lingxiang; Ye, Zhizhen

    2015-03-01

    Ion implantation was used to dope Na acceptor into ZnO single crystals. With three mixed implantation energies, uniform depth distribution of Na ion in the surface region (~300 nm) of ZnO bulk crystals is achieved. Via post-implantation annealing, a donor-acceptor pair recombination band is identified in the low-temperature photoluminescence spectra, from which the energy level of Na-related acceptor in single crystalline ZnO is estimated to be 300 meV. A p-n junction based on this ZnO-Na layer shows rectifying characteristics, confirming the p-type conductivity.

  14. ESS-Bilbao light-ion linear accelerator and neutron source: design and applications

    NASA Astrophysics Data System (ADS)

    Abad, E.; Arredondo, I.; Badillo, I.; Belver, D.; Bermejo, F. J.; Bustinduy, I.; Cano, D.; Cortazar, D.; de Cos, D.; Djekic, S.; Domingo, S.; Echevarria, P.; Eguiraun, M.; Etxebarria, V.; Fernandez, D.; Fernandez, F. J.; Feuchtwanger, J.; Garmendia, N.; Harper, G.; Hassanzadegan, H.; Jugo, J.; Legarda, F.; Magan, M.; Martinez, R.; Megia, A.; Muguira, L.; Mujika, G.; Muñoz, J. L.; Ortega, A.; Ortega, J.; Perlado, M.; Portilla, J.; Rueda, I.; Sordo, F.; Toyos, V.; Vizcaino, A.

    2011-10-01

    The baseline design for the ESS-Bilbao light-ion linear accelerator and neutron source has been completed and the normal conducting section of the linac is at present under construction. The machine has been designed to be compliant with ESS specifications following the international guidelines of such project as described in Ref. [1]. The new accelerator facility in Bilbao will serve as a base for support of activities on accelerator physics carried out in Spain and southern Europe in the frame of different ongoing international collaborations. Also, a number of applications have been envisaged in the new Bilbao facility for the outgoing light ion beams as well as from fast neutrons produced by low-energy neutron-capture targets, which are briefly described.

  15. A comb-sampling method for enhanced mass analysis in linear electrostatic ion traps

    SciTech Connect

    Greenwood, J. B.; Kelly, O.; Calvert, C. R.; Duffy, M. J.; King, R. B.; Belshaw, L.; Graham, L.; Alexander, J. D.; Williams, I. D.; Bryan, W. A.; Turcu, I. C. E.; Cacho, C. M.; Springate, E.

    2011-04-15

    In this paper an algorithm for extracting spectral information from signals containing a series of narrow periodic impulses is presented. Such signals can typically be acquired by pickup detectors from the image-charge of ion bunches oscillating in a linear electrostatic ion trap, where frequency analysis provides a scheme for high-resolution mass spectrometry. To provide an improved technique for such frequency analysis, we introduce the CHIMERA algorithm (Comb-sampling for High-resolution IMpulse-train frequency ExtRAaction). This algorithm utilizes a comb function to generate frequency coefficients, rather than using sinusoids via a Fourier transform, since the comb provides a superior match to the data. This new technique is developed theoretically, applied to synthetic data, and then used to perform high resolution mass spectrometry on real data from an ion trap. If the ions are generated at a localized point in time and space, and the data is simultaneously acquired with multiple pickup rings, the method is shown to be a significant improvement on Fourier analysis. The mass spectra generated typically have an order of magnitude higher resolution compared with that obtained from fundamental Fourier frequencies, and are absent of large contributions from harmonic frequency components.

  16. Linear ion trap with added octopole field component: the property and method.

    PubMed

    Dang, Qiankun; Xu, Fuxing; Huang, Xiaohua; Fang, Xiang; Wang, Rizhi; Ding, Chuan-Fan

    2015-12-01

    It is well known that superimposition of some positive octopole field will benefit the performance of ion trap mass analyzer. In the radial-ejection linear ion trap (LIT), adding some octopole field component to the main quadrupole field is usually accomplished by stretching the ejection rod pair. In this study, the effect of octopole potential and some other higher order potential on the performance of LIT mass analyzer is investigated. A simple and effective method, which is to add some octopole component by building a LIT with a pair of rectangular electrodes and a pair of semi-circular electrodes, is reported. Its properties were studied by numerical simulations and experiments. The results showed that a certain amount of positive octopole component could be produced by simply adjusting the position and width of the rectangular electrodes. A resolution of over 1200 at m/z 609 (~1600 Da/s) was observed in this type of LIT. They also performed tandem mass spectrometry well. The device with optimum geometry for ion ejection from rectangular electrodes provided comparable performance to that for ion ejection from semi-circular electrodes. This type of LIT design is easy for fabrication and assembly. PMID:26634975

  17. Sensing Nature's Electric Fields: Ion Channels as Active Elements of Linear Amplification

    NASA Astrophysics Data System (ADS)

    Bezrukov, Sergey M.

    2003-05-01

    Given the parameters of familiar cellular elements — voltage-sensitive ion channels, carriers, pumps, phospholipid insulators, and electrolytic conductors — is it possible to construct an amplifier whose sensitivity matches the 5 nV/cm threshold found in behavioral experiments on elasmobranch fish? Or, in addition to clever circuitry that uses commonly known elements and principles, do we need something else to understand this sensitivity? The resolution of this question is important not only for studies in sensory biophysics seeking to reveal underlying mechanisms and molecular structures. More generally, it deepens our appreciation of the stochastic nature of inter- and intra-cellular control circuits. Here I analyze a simplified circuit involving negative differential resistance of voltage-sensitive ion channels. The analysis establishes an off-equilibrium criterion for amplification, shows that ion channels are the dominant noise sources, and, by minimizing channel noise within the given constraints, demonstrates that generic voltage-sensitive ion channels are likely candidates for the active elements of the linear cellular amplifiers. Finally, I highlight a number of unsolved issues.

  18. The Crystal Structure of PPIL1 Bound to Cyclosporine A Suggests a Binding Mode for a Linear Epitope of the SKIP Protein

    PubMed Central

    Stegmann, Christian M.; Lührmann, Reinhard; Wahl, Markus C.

    2010-01-01

    Background The removal of introns from pre-mRNA is carried out by a large macromolecular machine called the spliceosome. The peptidyl-prolyl cis/trans isomerase PPIL1 is a component of the human spliceosome and binds to the spliceosomal SKIP protein via a binding site distinct from its active site. Principal Findings Here, we have studied the PPIL1 protein and its interaction with SKIP biochemically and by X-ray crystallography. A minimal linear binding epitope derived from the SKIP protein could be determined using a peptide array. A 36-residue region of SKIP centred on an eight-residue epitope suffices to bind PPIL1 in pull-down experiments. The crystal structure of PPIL1 in complex with the inhibitor cyclosporine A (CsA) was obtained at a resolution of 1.15 Å and exhibited two bound Cd2+ ions that enabled SAD phasing. PPIL1 residues that have previously been implicated in binding of SKIP are involved in the coordination of Cd2+ ions in the present crystal structure. Employing the present crystal structure, the determined minimal binding epitope and previously published NMR data [1], a molecular docking study was performed. In the docked model of the PPIL1·SKIP interaction, a proline residue of SKIP is buried in a hydrophobic pocket of PPIL1. This hydrophobic contact is encircled by several hydrogen bonds between the SKIP peptide and PPIL1. Conclusion We characterized a short, linear epitope of SKIP that is sufficient to bind the PPIL1 protein. Our data indicate that this SKIP peptide could function in recruiting PPIL1 into the core of the spliceosome. We present a molecular model for the binding mode of SKIP to PPIL1 which emphasizes the versatility of cyclophilin-type PPIases to engage in additional interactions with other proteins apart from active site contacts despite their limited surface area. PMID:20368803

  19. A linear dispersion relation for the hybrid kinetic-ion/fluid-electron model of plasma physics

    NASA Astrophysics Data System (ADS)

    Told, D.; Cookmeyer, J.; Astfalk, P.; Jenko, F.

    2016-07-01

    A dispersion relation for a commonly used hybrid model of plasma physics is developed, which combines fully kinetic ions and a massless-electron fluid description. Although this model and variations of it have been used to describe plasma phenomena for about 40 years, to date there exists no general dispersion relation to describe the linear wave physics contained in the model. Previous efforts along these lines are extended here to retain arbitrary wave propagation angles, temperature anisotropy effects, as well as additional terms in the generalized Ohm’s law which determines the electric field. A numerical solver for the dispersion relation is developed, and linear wave physics is benchmarked against solutions of a full Vlasov–Maxwell dispersion relation solver. This work opens the door to a more accurate interpretation of existing and future wave and turbulence simulations using this type of hybrid model.

  20. Effect of rare earth ions on the properties of glycine phosphite single crystals

    NASA Astrophysics Data System (ADS)

    Senthilkumar, K.; Moorthy Babu, S.; Kumar, Binay; Bhagavannarayana, G.

    2013-01-01

    Optically transparent glycine phosphite (GPI) single crystals doped with rare earth metal ions (Ce, Nd and La) were grown from aqueous solution by employing the solvent evaporation and slow cooling methods. Co-ordination of dopants with GPI was confirmed by X-ray fluorescence spectroscopic analysis. Single crystal X-ray diffraction analysis was carried out to determine the lattice parameters and to analyze the structural morphology of GPI with dopants, which indicates that cell parameters of doped crystals were significantly varied with pure GPI. Crystalline perfection of doped GPI crystals was determined by high resolution X-ray diffraction analysis by means of full width at half maximum values. Influence of the dopants on the optical properties of the material was determined. Paraelectric to ferroelectric transition temperature (Tc) of doped GPI crystals were identified using differential scanning calorimetric measurements. Piezoelectric charge coefficient d33 was measured for pure and doped GPI crystals. Hysteresis (P-E) loop was traced for ferroelectric b-axis and (100) plane of pure and doped GPI crystals with different biasing field and ferroelectric parameters were calculated. Mechanical stability of crystals was determined by Vickers microhardness measurements; elastic stiffness constant 'C11' and yield strength 'σy' were calculated from hardness values. Mechanical and ferroelectric properties of doped crystals were improved with doping of rare earth metals.

  1. Highly non-linear solid core photonic crystal fiber with one nano hole

    SciTech Connect

    Gangwar, Rahul Kumar Bhardwaj, Vanita Singh, Vinod Kumar

    2015-08-28

    The numerical study of newly designed solid core photonic crystal fiber (SCPCF) having three hexagonal air hole rings in cladding region and one small nano hole at the center are presented. By using full vectorial finite element method (FV-FEM), we analyses the optical properties like effective area, nonlinearity and confinement loss of the proposed PCF. Results show that the change in core diameter controls the effective area, nonlinearity and confinement loss. A low effective area (3.34 µm{sup 2}), high nonlinearity (36.34 W{sup −1}km{sup −1}) and low confinement loss (0.00106 dB/km) are achieved at the communication wavelength 1.55 µm for the SCPCF having core air hole diameter 0.10 µm, cladding air holes diameter 1.00 µm and pitch 2.50 µm. This type of PCF is very useful in non-linear applications such as supercontinuum generation, four wave mixing, second harmonic generation etc.

  2. Linear magnetoresistance and zero-field anomalies in HfNiSn single crystals

    NASA Astrophysics Data System (ADS)

    Steinke, Lucia; Kistner-Morris, Jedediah J.; Deng, Haiming; Geschwind, Gayle; Aronson, Meigan C.

    The Half-Heusler compound HfNiSn is probably best known as a candidate material for thermoelectric applications, and studies of its properties have mainly focused on polycrystalline samples and thin films. However, magnetotransport studies of HfNiSn show unusual transport properties like linear magnetoresistance (LMR), where single-crystalline samples of HfNiSn exhibit unexpected LMR at very low fields. In this work, we optimized the solution growth of HfNiSn to obtain high-quality single crystals, where electrical transport measurements show that it is a compensated semimetal below ~ 200 K, where the Hall voltage is zero. At higher temperatures, we see a finite Hall contribution from activated excess carriers. In the semimetallic regime, we observe transport anomalies like resistive signals that strongly depend on contact configuration, and LMR below 5 K. Both low-field DC and low frequency AC magntization measurements show pronounced diamagnetic behavior and the onset of paramagnetism below 4 K. High-frequency diamagnetic screening may be attributed to a decreased skin depth with decreased resistance, but this scenario seems unlikely in HfNiSn since the measured resistance increases steeply at the lowest temperatures This research was supported by the Army Research Office.

  3. New method for preparing a liquid crystal polymer that exhibits linearly polarized white fluorescence

    NASA Astrophysics Data System (ADS)

    Zheng, Shi-jun; Kun, Wang; Kobayashi, Takaomi

    2011-03-01

    With the aim of developing a single-chain white-light-emitting polymer, liquid crystal (LC) polymers with a shish-kebab-type moiety on their cross-conjugated (p-phenylene)s-poly(p-phenylenevinylene)s main chain were synthesized by Gilch polymerization. They were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarizing optical microscopy (POM). 1H-NMR indicated that the polymers had a shish-kebab structure, which strongly suppressed the formation of structural defects in the polymers. DSC revealed that the polymers had thermotropic LC properties, indicating that the LC polymers were enantiotropic. XRD showed that the polymers had a mesophase, which implies that they were in a smectic LC phase. A polymer with "kebabs" of 2,5-bis(4'-alkoxyphenyl)benzene was combined with an aligned polyimide film with orientated microgrooves. The polymer main chain was aligned due to the orientation of the "kebabs" of the uniform cross-conjugated structure. It lay between the kebabs and the "shish" of the polymer main chains. The aligned polymer main chain emitted yellow light while and the oriented LC side chains emitted blue light emission. These two emissions resulted in linearly polarized white fluorescence.

  4. A linear diffusion model for ion current across blocking grain boundaries in oxygen-ion and proton conductors.

    PubMed

    Kim, Seong K; Khodorov, Sergey; Lubomirsky, Igor; Kim, Sangtae

    2014-07-28

    We demonstrate the applicability of the linear diffusion model recently proposed for the current-voltage, Igb-Ugb, characteristics of blocking grain boundaries in solid electrolytes to various oxygen-ion and proton conductors: the model precisely reproduces the Igb-Ugb characteristics of La-, Sm-, Gd-, and Y-doped ceria as well as Y-doped barium zirconate to provide accurate explanations to the "power law" behavior of the Igb-Ugb relationship, i.e. Igb ∝ Ugb(n), experimentally observed. The model also predicts that the grain-boundary potential, Ψgb, in doped ceria weakly depends on temperature, if the trapped charge remains constant, and that the value of Ψgb can be determined from the value of the power n. Furthermore, the model provides a plausible explanation for the increase in the Ψgb with temperature observed for the proton conductor in which the concentration of the charge carrier decreases with temperature. Hence, it is evident that the linear diffusion model is robust and applicable to grain boundaries in a large variety of practically important solid electrolytes. PMID:24930884

  5. Non-local gyrokinetic model of linear ion-temperature-gradient modes

    SciTech Connect

    Moradi, S.; Anderson, J.

    2012-08-15

    The non-local properties of anomalous transport in fusion plasmas are still an elusive topic. In this work, a theory of non-local linear ion-temperature-gradient (ITG) drift modes while retaining non-adiabatic electrons and finite temperature gradients is presented, extending the previous work [S. Moradi et al., Phys. Plasmas 18, 062106 (2011)]. A dispersion relation is derived to quantify the effects on the eigenvalues of the unstable ion temperature gradient modes and non-adiabatic electrons on the order of the fractional velocity operator in the Fokker-Planck equation. By solving this relation for a given eigenvalue, it is shown that as the linear eigenvalues of the modes increase, the order of the fractional velocity derivative deviates from two and the resulting equilibrium probability density distribution of the plasma, i.e., the solution of the Fokker-Planck equation, deviates from a Maxwellian and becomes Levy distributed. The relative effect of the real frequency of the ITG mode on the deviation of the plasma from Maxwellian is larger than from the growth rate. As was shown previously the resulting Levy distribution of the plasma may in turn significantly alter the transport as well.

  6. Linear and nonlinear analysis of dust acoustic waves in dissipative space dusty plasmas with trapped ions

    NASA Astrophysics Data System (ADS)

    El-Hanbaly, A. M.; El-Shewy, E. K.; Sallah, M.; Darweesh, H. F.

    2015-05-01

    The propagation of linear and nonlinear dust acoustic waves in a homogeneous unmagnetized, collisionless and dissipative dusty plasma consisted of extremely massive, micron-sized, negative dust grains has been investigated. The Boltzmann distribution is suggested for electrons whereas vortex-like distribution for ions. In the linear analysis, the dispersion relation is obtained, and the dependence of damping rate of the waves on the carrier wave number , the dust kinematic viscosity coefficient and the ratio of the ions to the electrons temperatures is discussed. In the nonlinear analysis, the modified Korteweg-de Vries-Burgers (mKdV-Burgers) equation is derived via the reductive perturbation method. Bifurcation analysis is discussed for non-dissipative system in the absence of Burgers term. In the case of dissipative system, the tangent hyperbolic method is used to solve mKdV-Burgers equation, and yield the shock wave solution. The obtained results may be helpful in better understanding of waves propagation in the astrophysical plasmas as well as in inertial confinement fusion laboratory plasmas.

  7. Strontium Ions Substitution in Brushite Crystals: The Role of Strontium Chloride

    PubMed Central

    Alkhraisat, Mohammad H.; Rueda, Carmen; Cabarcos, Enrique López

    2011-01-01

    The incorporation of strontium chloride to brushite cement was successful to introduce strontium ions within the lattice of brushite crystals. The effect of strontium ions on brushite cement properties was concentration dependent; such that, the addition of 5% and 10% (w/w) SrCl2 significantly increased the cement FST and the addition of 10% SrCl2 decreased the cement tensile strength. Further, cement weight loss was shown to be increased by cement modification with SrCl2. The combination of ionic substitution and the degradability of brushite cements would constitute a system for the local delivery of strontium ions in the treatment of osteoporosis. PMID:24956162

  8. Ion-beam induced domain structure in piezoelectric PMN-PT single crystal

    SciTech Connect

    Kim, Kyou-Hyun; Payne, David A.; Zuo Jianmin

    2010-12-27

    We report an investigation of the domain structure in Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-30%PbTiO{sub 3} single crystals after ion milling. We show that ion milling induces microdomains, typically 0.1-1 {mu}m in size. The induced microdomains disappear after temperature annealing or electric poling, leaving behind nanodomains of a few nanometers in size. We attribute the microdomains to surface stress induced by ion milling. The results demonstrate the general importance of separating sample preparation artifacts from the true domain structure in the study of ferroic materials.

  9. Synthesis of guanidinium–sulfonimide ion pairs: towards novel ionic liquid crystals

    PubMed Central

    Butschies, Martin; Neidhardt, Manuel M; Mansueto, Markus; Tussetschläger, Stefan

    2013-01-01

    Summary The recently introduced concept of ionic liquid crystals (ILCs) with complementary ion pairs, consisting of both, mesogenic cation and anion, was extended from guanidinium sulfonates to guanidinium sulfonimides. In this preliminary study, the synthesis and mesomorphic properties of selected derivatives were described, which provide the first example of an ILC with the sulfonimide anion directly attached to the mesogenic unit. PMID:23766823

  10. Investigations of hyperfine and isotope structures in optical spectra of crystals with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Popova, M. N.

    2015-10-01

    This is a review of works on hyperfine and isotope structures in the spectra of rare-earth ions in crystals that have been performed at the Laboratory of Fourier Spectroscopy of the Institute for Spectroscopy, Russian Academy of Sciences. The applicability of these studies to the development of optical quantum memory is discussed.

  11. Diffusion control of an ion by another in LiNbO3 and LiTaO3 crystals

    PubMed Central

    Zhang, De-Long; Zhang, Qun; Qiu, Cong-Xian; Wong, Wing-Han; Yu, Dao-Yin; Yue-Bun Pun, Edwin

    2015-01-01

    Diffusion-doping is an effective, practical method to improve material properties and widen material application. Here, we demonstrate a new physical phenomenon: diffusion control of an ion by another in LiNbO3 and LiTaO3 crystals. We exemplify Ti4+/Xn+ (Xn+ = Sc3+, Zr4+, Er3+) co-diffusion in the widely studied LiNbO3 and LiTaO3 crystals. Some Ti4+/Xn+-co-doped LiNbO3 and LiTaO3 plates were prepared by co-diffusion of stacked Ti-metal and Er-metal (Sc2O3 or ZrO2) films coated onto LiNbO3 or LiTaO3 substrates. The Ti4+/Xn+-co-diffusion characteristics were studied by secondary ion mass spectrometry. In the Xn+-only diffusion case, the Xn+ diffuses considerably slower than the Ti4+. In the Ti4+/Xn+ co-diffusion case, the faster Ti4+ controls the diffusion of the slower Xn+. The Xn+ diffusivity increases linearly with the initial Ti-metal thickness and the increase depends on the Xn+ species. The phenomenon is ascribed to the generation of additional defects induced by the diffusion of faster Ti4+ ions, which favors and assists the subsequent diffusion of slower Xn+ ion. For the diffusion system studied here, it can be utilized to substantially shorten device fabrication period, improve device performance and produce new materials. PMID:25941037

  12. Using support vector machines to improve elemental ion identification in macromolecular crystal structures

    SciTech Connect

    Morshed, Nader; Echols, Nathaniel; Adams, Paul D.

    2015-05-01

    A method to automatically identify possible elemental ions in X-ray crystal structures has been extended to use support vector machine (SVM) classifiers trained on selected structures in the PDB, with significantly improved sensitivity over manually encoded heuristics. In the process of macromolecular model building, crystallographers must examine electron density for isolated atoms and differentiate sites containing structured solvent molecules from those containing elemental ions. This task requires specific knowledge of metal-binding chemistry and scattering properties and is prone to error. A method has previously been described to identify ions based on manually chosen criteria for a number of elements. Here, the use of support vector machines (SVMs) to automatically classify isolated atoms as either solvent or one of various ions is described. Two data sets of protein crystal structures, one containing manually curated structures deposited with anomalous diffraction data and another with automatically filtered, high-resolution structures, were constructed. On the manually curated data set, an SVM classifier was able to distinguish calcium from manganese, zinc, iron and nickel, as well as all five of these ions from water molecules, with a high degree of accuracy. Additionally, SVMs trained on the automatically curated set of high-resolution structures were able to successfully classify most common elemental ions in an independent validation test set. This method is readily extensible to other elemental ions and can also be used in conjunction with previous methods based on a priori expectations of the chemical environment and X-ray scattering.

  13. Post-crystallization Improvement of RNA Crystals by Synergistic Ion Exchange and Dehydration

    PubMed Central

    Zhang, Jinwei; Ferré-D’Amaré, Adrian R.

    2016-01-01

    Compared to the recent dramatic growth in the numbers of genome-wide and functional studies of complex non-coding RNAs, mechanistic and structural analyses have lagged behind. A major technical bottleneck in the structural determination of large RNAs and their complexes is preparation of diffracting crystals. Empirically, a vast majority of such RNA crystals fail to diffract X-rays to usable resolution (~4 Å) due to their inherent disorder and non-specific packing within the crystals. Here, we present a protocol that combines post-crystallization cation replacement and dehydration that dramatically improved the diffraction quality of crystals of a large gene-regulatory mRNA-tRNA complex. This procedure not only extended the resolution limit of X-ray data from 8.5 to 3.2 Å, but also significantly improved the quality of the data, enabling de novo phasing and structure determination. Because it exploits the general importance of counterions and solvation in RNA structure, this procedure may prove broadly useful in the crystallographic analyses of other large non-coding RNAs.

  14. Towards a unified linear kinetic transport model with the trace ion module for EIRENE

    PubMed Central

    Seebacher, J.; Kendl, A.

    2012-01-01

    Linear kinetic Monte Carlo particle transport models are frequently employed in fusion plasma simulations to quantify atomic and surface effects on the main plasma flow dynamics. Separate codes are used for transport of neutral particles (incl. radiation) and charged particles (trace impurity ions). Integration of both modules into main plasma fluid solvers provides then self-consistent solutions, in principle. The required interfaces are far from trivial, because rapid atomic processes in particular in the edge region of fusion plasmas require either smoothing and resampling, or frequent transfer of particles from one into the other Monte Carlo code. We propose a different scheme here, in which despite the inherently different mathematical form of kinetic equations for ions and neutrals (e.g. Fokker–Planck vs. Boltzmann collision integrals) both types of particle orbits can be integrated into one single code. We show that the approximations and shortcomings of this “single sourcing” concept (e.g., restriction to explicit ion drift orbit integration) can be fully tolerable in a wide range of typical fusion edge plasma conditions, and be overcompensated by the code-system simplicity, as well as by inherently ensured consistency in geometry (one single numerical grid only) and (the common) atomic and surface process modules. PMID:22474397

  15. Ion species control in high flux deuterium plasma beams produced by a linear plasma generator

    SciTech Connect

    Luo, G.-N.; Shu, W.M.; Nakamura, H.; O'Hira, S.; Nishi, M.

    2004-11-01

    The ion species ratios in low energy high flux deuterium plasma beams formed in a linear plasma generator were measured by a quadrupole mass spectrometer. And the species control in the plasma generator was evaluated by changing the operational parameters like neutral pressure, arc current, and axial magnetic confinement to the plasma column. The measurements reveal that the lower pressures prefer to form more D{sup +} ions, and the medium magnetic confinement at the higher pressures results in production of more D{sub 2}{sup +}, while the stronger confinement and/or larger arc current are helpful to D{sub 2}{sup +} conversion into D{sub 3}{sup +}. Therefore, the ion species can be controlled by adjusting the operational parameters of the plasma generator. With suitable adjustment, we can achieve plasma beams highly enriched with a single species of D{sup +}, D{sub 2}{sup +}, or D{sub 3}{sup +}, to a ratio over 80%. It has been found that the axial magnetic configuration played a significant role in the formation of D{sub 3}{sup +} within the experimental pressure range.

  16. Towards a unified linear kinetic transport model with the trace ion module for EIRENE

    NASA Astrophysics Data System (ADS)

    Seebacher, J.; Kendl, A.

    2012-04-01

    Linear kinetic Monte Carlo particle transport models are frequently employed in fusion plasma simulations to quantify atomic and surface effects on the main plasma flow dynamics. Separate codes are used for transport of neutral particles (incl. radiation) and charged particles (trace impurity ions). Integration of both modules into main plasma fluid solvers provides then self-consistent solutions, in principle. The required interfaces are far from trivial, because rapid atomic processes in particular in the edge region of fusion plasmas require either smoothing and resampling, or frequent transfer of particles from one into the other Monte Carlo code. We propose a different scheme here, in which despite the inherently different mathematical form of kinetic equations for ions and neutrals (e.g. Fokker-Planck vs. Boltzmann collision integrals) both types of particle orbits can be integrated into one single code. We show that the approximations and shortcomings of this “single sourcing” concept (e.g., restriction to explicit ion drift orbit integration) can be fully tolerable in a wide range of typical fusion edge plasma conditions, and be overcompensated by the code-system simplicity, as well as by inherently ensured consistency in geometry (one single numerical grid only) and (the common) atomic and surface process modules.

  17. Integrated Cavity QED in a linear Ion Trap Chip for Enhanced Light Collection

    NASA Astrophysics Data System (ADS)

    Benito, Francisco; Jonathan, Sterk; Boyan, Tabakov; Haltli, Raymond; Tigges, Chris; Stick, Daniel; Balin, Matthew; Moehring, David

    2012-06-01

    Realizing a scalable trapped-ion quantum information processor may require integration of tools to manipulate qubits into trapping devices. We present efforts towards integrating a 1 mm optical cavity into a microfabricated surface ion trap to efficiently connect nodes in a quantum network. The cavity is formed by a concave mirror and a flat coated silicon mirror around a linear trap where ytterbium ions can be shuttled in and out of the cavity mode. By utilizing the Purcell effect to increase the rate of spontaneous emission into the cavity mode, we expect to collect up to 13% of the emitted photons. This work was supported by Sandia's Laboratory Directed Research and Development (LDRD) and the Intelligence Advanced Research Projects Activity (IARPA). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  18. Cr3+ ions in hydrogenated and proton exchanged lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Kamiska, A.; Arizmendi, L.; Barcz, A.; Usakowska, E.; Suchocki, A.

    2004-01-01

    We studied influence of annealing in water vapour and proton exchange on high-pressure low-temperature luminescence spectra of near stoichiometric LN:Cr, MgO crystals, containing both CrLi and CrNb centers by using diamond-anvil cell technique. The observed changes of the spectra of Cr3+ ions are associated with the larger inhomogeneous broadening and increase of the splitting of the 2E level of the so called CrNb center. This shows that neither increase of hydrogen concentration in LN by almost two orders of magnitude (from 1018 to almost 1020 cm-3) nor proton-exchange procedure do not create any new optically active Cr3+ centers in those crystals. This does not support the hypothesis about the close compensation of Cr3+Nb sites in LiNbO3 crystals by hydrogen ions.

  19. Secondary nucleation of gibbsite crystals from synthetic Bayer liquors: effect of alkali metal ions

    NASA Astrophysics Data System (ADS)

    Li, Jun; Prestidge, Clive A.; Addai-Mensah, Jonas

    2000-11-01

    The effect of alkali metal ions (Na + versus K +) on secondary nucleation of gibbsite ( γ-Al(OH) 3) from synthetic Bayer liquors has been investigated under seeded, isothermal, batch crystallisation conditions. The nucleation kinetics showed a fourth-order dependence upon Al(III) relative supersaturation and a strong temperature effect. An activation energy of 132 kJ mol -1, which was independent of alkali metal ion, was calculated. Secondary nucleation and subsequent crystal growth rates however, were greater in sodium than in potassium aluminate solution. The Arrhenius, pre-exponential factor was at least three times larger in sodium than in potassium aluminate solutions at equivalent crystal surface area, similar supersaturation and temperature. The results indicated that secondary nucleation of Al(OH) 3 is a chemical reaction-controlled process which is alkali metal ion-mediated. Na + ions provide a more favourable pathway than potassium ions for the formation of Al(III)-containing clusters, higher collision frequency between the species and crystal surface, and faster growth of potential secondary nuclei in the solutions.

  20. Hexagonal plaquette spin-spin interactions and quantum magnetism in a two-dimensional ion crystal

    NASA Astrophysics Data System (ADS)

    Nath, R.; Dalmonte, M.; Glaetzle, A. W.; Zoller, P.; Schmidt-Kaler, F.; Gerritsma, R.

    2015-06-01

    We propose a trapped ion scheme en route to realize spin Hamiltonians on a Kagome lattice which, at low energies, are described by emergent {{{Z}}}2 gauge fields, and support a topological quantum spin liquid ground state. The enabling element in our scheme is the hexagonal plaquette spin-spin interactions in a two-dimensional ion crystal. For this, the phonon-mode spectrum of the crystal is engineered by standing-wave optical potentials or by using Rydberg excited ions, thus generating localized phonon-modes around a hexagon of ions selected out of the entire two-dimensional crystal. These tailored modes can mediate spin-spin interactions between ion-qubits on a hexagonal plaquette when subject to state-dependent optical dipole forces. We discuss how these interactions can be employed to emulate a generalized Balents-Fisher-Girvin model in minimal instances of one and two plaquettes. This model is an archetypical Hamiltonian in which gauge fields are the emergent degrees of freedom on top of the classical ground state manifold. Under realistic situations, we show the emergence of a discrete Gauss’s law as well as the dynamics of a deconfined charge excitation on a gauge-invariant background using the two-plaquettes trapped ions spin-system. The proposed scheme in principle allows further scaling in a future trapped ion quantum simulator, and we conclude that our work will pave the way towards the simulation of emergent gauge theories and quantum spin liquids in trapped ion systems.

  1. Crystal structure of an acetyl esterase complexed with acetate ion provides insights into the catalytic mechanism.

    PubMed

    Uechi, Keiko; Kamachi, Saori; Akita, Hironaga; Mine, Shouhei; Watanabe, Masahiro

    2016-08-26

    We previously reported the crystal structure of an acetyl esterase (TcAE206) belonging to carbohydrate esterase family 3 from Talaromyces cellulolyticus. In this study, we solved the crystal structure of an S10A mutant of TcAE206 complexed with an acetate ion. The acetate ion was stabilized by three hydrogen bonds in the oxyanion hole instead of a water molecule as in the structure of wild-type TcAE206. Furthermore, the catalytic triad residue His182 moved 0.8 Å toward the acetate ion upon substrate entering the active site, suggesting that this movement is necessary for completion of the catalytic reaction. PMID:27329813

  2. The determination of dopant ion valence distributions in insulating crystals using XANES measurements.

    PubMed

    Hughes-Currie, Rosa B; Ivanovskikh, Konstantin V; R Wells, Jon-Paul; Reid, Michael F; Gordon, Robert A

    2016-04-01

    Ytterbium-doped wide-bandgap fluoride crystals CaF2, SrF2 and NaMgF3 have been measured using x-ray absorption near edge structure (XANES) on the L3 edge to determine the ratio of trivalent to divalent Yb ions present in the crystals. This study improves upon previous XANES measurements of dopant ion valency by taking into account the x-ray emission transition probabilities for the divalent and trivalent species instead of simply assuming that the relative concentrations may be determined by the ratio of the x-ray excitation band areas. Trivalent to divalent ratios as high as 5 are inferred even at low total dopant ion concentrations of 0.05 mol% Yb. PMID:26941175

  3. The determination of dopant ion valence distributions in insulating crystals using XANES measurements

    NASA Astrophysics Data System (ADS)

    Hughes-Currie, Rosa B.; Ivanovskikh, Konstantin V.; Wells, Jon-Paul R.; Reid, Michael F.; Gordon, Robert A.

    2016-04-01

    Ytterbium-doped wide-bandgap fluoride crystals CaF2, SrF2 and NaMgF3 have been measured using x-ray absorption near edge structure (XANES) on the L3 edge to determine the ratio of trivalent to divalent Yb ions present in the crystals. This study improves upon previous XANES measurements of dopant ion valency by taking into account the x-ray emission transition probabilities for the divalent and trivalent species instead of simply assuming that the relative concentrations may be determined by the ratio of the x-ray excitation band areas. Trivalent to divalent ratios as high as 5 are inferred even at low total dopant ion concentrations of 0.05 mol% Yb.

  4. Application of a volume holographic grating in a CaF2 crystal for measuring linear displacements with nanoscale accuracy

    NASA Astrophysics Data System (ADS)

    Shcheulin, A. S.; Angervaks, A. E.; Kupchikov, A. K.; Verkhovskii, E. B.; Ryskin, A. I.

    2014-12-01

    A holographic method for measuring linear displacements based on the use of a highly stable volume scale hologram recorded in an additively colored calcium fluoride crystal with photochromic color centers is proposed and experimentally approved. The essence of this method lies in measuring and analyzing harmonic signals formed during linear displacement of crystal with a volume hologram in an external interference field. A physical model of the formation of harmonic signals in photodetectors when measuring displacements is considered, and a mathematical method for calculating linear displacements by plotting a Lissajous figure is substantiated. A laboratory breadboard of a device for measuring linear displacements in a range of 10 mm, limited by the aperture of crystal with a recorded 8.7-mm-thick hologram, is designed. When using a scale hologram with a period of 2.18 μm and a 632.8-nm He-Ne laser for reading this hologram, the error in measuring displacements by this method is 9 nm at a resolution of 3 nm.

  5. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator

    SciTech Connect

    Yu Haijun; Zhu Jun; Chen Nan; Xie Yutong; Jiang Xiaoguo; Jian Cheng

    2010-04-15

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 10{sup 21}/m{sup 3} and 2-3 mm/{mu}s, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  6. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator

    NASA Astrophysics Data System (ADS)

    Yu, Haijun; Zhu, Jun; Chen, Nan; Xie, Yutong; Jiang, Xiaoguo; Jian, Cheng

    2010-04-01

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 1021/m3 and 2-3 mm/μs, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  7. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator.

    PubMed

    Yu, Haijun; Zhu, Jun; Chen, Nan; Xie, Yutong; Jiang, Xiaoguo; Jian, Cheng

    2010-04-01

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 10(21)/m(3) and 2-3 mm/micros, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA. PMID:20441331

  8. Design and Performance Evaluation of a Linear Ion Trap Mass Analyzer Featuring Half Round Rod Electrodes

    NASA Astrophysics Data System (ADS)

    Li, Xiaoxu; Zhang, Xiaohua; Yao, Rujiao; He, Yang; Zhu, Yongyong; Qian, Jie

    2015-05-01

    A novel linear ion trap mass analyzer featuring half round rod electrodes (HreLIT) has been built. It is mainly composed of two pairs of stainless steel electrodes which have a cross-section of half round rod and a pair of end electrodes. The HreLIT has a simple structure and so it could be assembled by hand with relatively high mechanical accuracy. The external dimension of HreLIT is 50 mm × 29.5 mm × 28 mm (length × width × height) and its internal volume is about 3.8 cm3. A home-made HreLIT mass spectrometer with three-stage vacuum system was built and the performance of HreLIT was characterized using reserpine solution and PPG standard solution. When the scan rate was 254 u/s, mass peak with FWHM of 0.14 u was achieved for ions with m/z 609, which corresponds to a mass resolution of 4350. The HreLIT was also operated at a low q value of 0.28 to extend its mass range. The experiment result showed a mass range of over 2800 u and the amplitude of radio frequency (rf) signal was only 1560 V (0-p). Three-stage tandem mass spectrometry was successfully performed in the HreLIT, and the collision-induced dissociation (CID) efficiencies of MS2 (CID of ions with m/z 609) and MS3 (CID of ions with m/z 448) were 78% and 59%, respectively.

  9. Trends in Atomic Parameters for Crystals and Free Ions across the Lanthanide Series: The Case of LaCl3:Ln(3+).

    PubMed

    Yeung, Y Y; Tanner, P A

    2015-06-18

    Analyses of the crystal field energy levels of the series LaCl3:Ln(3+) using a semiempirical Hamiltonian shows that only five ions (Pr, Nd, Pm, Dy, Ho) meet the criteria to avoid overfitting of the atomic part. A new parameter (SNES) has been introduced to represent the strength of the normalized electrostatic repulsion for these ions. This parameter varies linearly (R(2)adj = 0.9994, N = 5) with the reciprocal of the radius of the tripositive lanthanide ion, as expected from the form of repulsive Coulomb interaction. The Slater parameters from the crystal field analyses, F(k)(corr) (i.e., corrected for the effects of the two-particle component of the three-body operator associated with the T(2) parameter), exhibit an exponential variation with the number of electrons, n, in 4f(n). This is explained by reference to the radial part of a hydrogen-like wave function. The ratio of F(k)(corr) with the ab initio free ion Slater parameter F(k)(ab initio) varies linearly with n. Fitted parameters F(k)(corr: free ion) from the free ion data for Pr(3+) and Nd(3+) show that the corresponding ab initio values are between 14 and 27% too high. The spin-orbit coupling constant from crystal field analyses (ζ4f) exhibits a quartic variation with atomic number, and the ratio ζ4f/ζ4f(ab initio) follows an exponential growth model with n. The results serve to confirm the hypothesis that smooth trends can be observed across the Ln(3+) series for the fitted parameters despite the fact that the majority of experimental data is lacking. PMID:25985076

  10. RETRACTED: Crystal growth and spectroscopic characterization of Aloevera amino acid added lithium sulfate monohydrate: A non-linear optical crystal

    NASA Astrophysics Data System (ADS)

    Manimekalai, R.; Antony Joseph, A.; Ramachandra Raja, C.

    2014-03-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal. This article has been retracted at the request of authors. According to the author we have reported Aloevera Amino Acid added Lithium sulphate monohydrate [AALSMH] crystal is a new nonlinear optical crystal. From the recorded high performance liquid chromatography spectrum, by matching the retention times with the known compounds, the amino acids present in our extract are identified as homocystine, isoleucine, serine, leucine and tyrosine. From the thin layer chromatography and colorimetric estimation techniques, presence of isoleucine was identified and it was also confirmed by NMR spectrum. From the above studies, we came to conclude that AALSMH is new nonlinear optical crystal. After further investigation, lattice parameter values of AALSMH are coinciding with lithium sulphate. Therefore we have decided to withdraw our paper. Sorry for the inconvenience and time spent.

  11. The linear and non-linear characterization of dust ion acoustic mode in complex plasma in presence of dynamical charging of dust

    SciTech Connect

    Bhattacharjee, Saurav Das, Nilakshi

    2015-10-15

    A systematic theoretical investigation has been carried out on the role of dust charging dynamics on the nature and stability of DIA (Dust Ion Acoustic) mode in complex plasma. The study has been made for both linear and non-linear scale regime of DIA mode. The observed results have been characterized in terms of background plasma responses towards dust surface responsible for dust charge fluctuation, invoking important dusty plasma parameters, especially the ion flow speed and dust size. The linear analyses confirm the nature of instability in DIA mode in presence of dust charge fluctuation. The instability shows a damping of DIA mode in subsonic flow regime followed by a gradual growth in instability in supersonic limit of ion flow. The strength of non-linearity and their existence domain is found to be driven by different dusty plasma parameters. As dust is ubiquitous in interstellar medium with plasma background, the study also addresses the possible effect of dust charging dynamics in gravito-electrostatic characterization and the stability of dust molecular clouds especially in proto-planetary disc. The observations are influential and interesting towards the understanding of dust settling mechanism and formation of dust environments in different regions in space.

  12. The linear and non-linear characterization of dust ion acoustic mode in complex plasma in presence of dynamical charging of dust

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Saurav; Das, Nilakshi

    2015-10-01

    A systematic theoretical investigation has been carried out on the role of dust charging dynamics on the nature and stability of DIA (Dust Ion Acoustic) mode in complex plasma. The study has been made for both linear and non-linear scale regime of DIA mode. The observed results have been characterized in terms of background plasma responses towards dust surface responsible for dust charge fluctuation, invoking important dusty plasma parameters, especially the ion flow speed and dust size. The linear analyses confirm the nature of instability in DIA mode in presence of dust charge fluctuation. The instability shows a damping of DIA mode in subsonic flow regime followed by a gradual growth in instability in supersonic limit of ion flow. The strength of non-linearity and their existence domain is found to be driven by different dusty plasma parameters. As dust is ubiquitous in interstellar medium with plasma background, the study also addresses the possible effect of dust charging dynamics in gravito-electrostatic characterization and the stability of dust molecular clouds especially in proto-planetary disc. The observations are influential and interesting towards the understanding of dust settling mechanism and formation of dust environments in different regions in space.

  13. Modification of phonon processes in nanostructured rare-earth-ion-doped crystals

    NASA Astrophysics Data System (ADS)

    Lutz, Thomas; Veissier, Lucile; Thiel, Charles W.; Cone, Rufus L.; Barclay, Paul E.; Tittel, Wolfgang

    2016-07-01

    Nano-structuring impurity-doped crystals affects the phonon density of states and thereby modifies the atomic dynamics induced by interaction with phonons. We propose the use of nano-structured materials in the form of powders or phononic bandgap crystals to enable or improve persistent spectral hole burning and coherence for inhomogeneously broadened absorption lines in rare-earth-ion-doped crystals. This is crucial for applications such as ultra-precise radio-frequency spectrum analyzers and optical quantum memories. As an example, we discuss how phonon engineering can enable spectral hole burning in erbium-doped materials operating in the convenient telecommunication band and present simulations for density of states of nano-sized powders and phononic crystals for the case of Y2SiO5 , a widely used material in current quantum memory research.

  14. Synthesis, structural, topographical, linear and nonlinear optical, electrical and mechanical properties of Bisthiourea zinc acetate single crystal

    NASA Astrophysics Data System (ADS)

    Rajendran, V.; Uma, J.

    2016-07-01

    Nonlinear optical material Bisthiourea Zinc Acetate (BTZA) was synthesized by slow evaporation solution growth technique. The grown crystals were characterised by Single crystal XRD and powder XRD studies. The presence of functional groups and the co-ordination of metal ions to Thiourea were confirmed by FTIR analysis. The UV-vis -NIR spectrum shows a low absorption in the entire visible and IR region. Optical band gap of the grown crystal was found to be 4.18 eV. The photoluminescence studies carried out and the crystal has blue emission. The Refractive Index was determined experimentally for the first time and found to be 1.508 for the incident wavelength of 632.8 nm. The second harmonic generation efficiency was determined using Kurtz and Perry powder technique and it was 0.7 times than that of the KDP crystal. Thermal properties were studied by thermo gravimetric analysis and differential thermal analysis. Dielectric studies were carried out at different frequencies for various temperatures. The mechanical behaviour of the grown crystal was studied using Vickers micro hardness tester. The growth mechanism and surface features are investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM).

  15. Metal electrode dependent field effect transistors made of lanthanide ion-doped DNA crystals

    NASA Astrophysics Data System (ADS)

    Reddy Dugasani, Sreekantha; Hwang, Taehyun; Kim, Jang Ah; Gnapareddy, Bramaramba; Kim, Taesung; Park, Sung Ha

    2016-03-01

    We fabricated lanthanide ion (Ln3+, e.g. Dy3+, Er3+, Eu3+, and Gd3+)-doped self-assembled double-crossover (DX) DNA crystals grown on the surface of field effect transistors (FETs) containing either a Cr, Au, or Ni electrode. Here we demonstrate the metal electrode dependent FET characteristics as a function of various Ln3+. The drain-source current (I ds), controlled by the drain-source voltage (V ds) of Ln3+-doped DX DNA crystals with a Cr electrode on an FET, changed significantly under various gate voltages (V g) due to the relative closeness of the work function of Cr to the energy band gap of Ln3+-DNA crystals compared to those of Au and Ni. For Ln3+-DNA crystals on an FET with either a Cr or Ni electrode at a fixed V ds, I ds decreased with increasing V g ranging from  -2 to 0 V and from 0 to  +3 V in the positive and negative regions, respectively. By contrast, I ds for Ln3+-DNA crystals on an FET with Au decreased with increasing V g in only the positive region due to the greater electronegativity of Au. Furthermore, Ln3+-DNA crystals on an FET exhibited behaviour sensitive to V g due to the appreciable charge carriers generated from Ln3+. Finally, we address the resistivity and the mobility of Ln3+-DNA crystals on an FET with different metal electrodes obtained from I ds-V ds and I ds-V g curves. The resistivities of Ln3+-DNA crystals on FETs with Cr and Au electrodes were smaller than those of pristine DNA crystals on an FET, and the mobility of Ln3+-DNA crystals on an FET with Cr was relatively higher than that associated with other electrodes.

  16. Thermal, mechanical, electrical, linear and nonlinear optical properties of L-arginine dihydrofluoride single crystal

    NASA Astrophysics Data System (ADS)

    Sankar, D.; Menon, Vinay Raj; Sagayaraj, P.; Madhavan, J.

    2010-01-01

    L-arginine dihydrofluoride of dimensions upto 15×10×9 mm 3 was successfully grown by slow evaporation technique from aqueous solution. The crystal was characterized by X-ray diffractometry, Elemental analysis, FT-IR, UV-Vis-NIR spectroscopy, thermal and microhardness studies. The dielectric constant and dielectric loss of the crystal were studied as function of frequency. Photoconductivity studies were also carried out on the sample. Kurtz powder SHG measurement confirms the NLO property of the grown crystals.

  17. Selective crystallization with preferred lithium-ion storage capability of inorganic materials.

    PubMed

    Liu, Fei; Song, Shuyan; Xue, Dongfeng; Zhang, Hongjie

    2012-01-01

    Lithium-ion batteries are supposed to be a key method to make a more efficient use of energy. In the past decade, nanostructured electrode materials have been extensively studied and have presented the opportunity to achieve superior performance for the next-generation batteries which require higher energy and power densities and longer cycle life. In this article, we reviewed recent research activities on selective crystallization of inorganic materials into nanostructured electrodes for lithium-ion batteries and discuss how selective crystallization can improve the electrode performance of materials; for example, selective exposure of surfaces normal to the ionic diffusion paths can greatly enhance the ion conductivity of insertion-type materials; crystallization of alloying-type materials into nanowire arrays has proven to be a good solution to the electrode pulverization problem; and constructing conversion-type materials into hollow structures is an effective approach to buffer the volume variation during cycling. The major goal of this review is to demonstrate the importance of crystallization in energy storage applications. PMID:22353373

  18. Selective crystallization with preferred lithium-ion storage capability of inorganic materials

    PubMed Central

    2012-01-01

    Lithium-ion batteries are supposed to be a key method to make a more efficient use of energy. In the past decade, nanostructured electrode materials have been extensively studied and have presented the opportunity to achieve superior performance for the next-generation batteries which require higher energy and power densities and longer cycle life. In this article, we reviewed recent research activities on selective crystallization of inorganic materials into nanostructured electrodes for lithium-ion batteries and discuss how selective crystallization can improve the electrode performance of materials; for example, selective exposure of surfaces normal to the ionic diffusion paths can greatly enhance the ion conductivity of insertion-type materials; crystallization of alloying-type materials into nanowire arrays has proven to be a good solution to the electrode pulverization problem; and constructing conversion-type materials into hollow structures is an effective approach to buffer the volume variation during cycling. The major goal of this review is to demonstrate the importance of crystallization in energy storage applications. PMID:22353373

  19. Linearized model collision operators for multiple ion species plasmas and gyrokinetic entropy balance equations

    SciTech Connect

    Sugama, H.; Watanabe, T.-H.; Nunami, M.

    2009-11-15

    Linearized model collision operators for multiple ion species plasmas are presented that conserve particles, momentum, and energy and satisfy adjointness relations and Boltzmann's H-theorem even for collisions between different particle species with unequal temperatures. The model collision operators are also written in the gyrophase-averaged form that can be applied to the gyrokinetic equation. Balance equations for the turbulent entropy density, the energy of electromagnetic fluctuations, the turbulent transport fluxes of particle and heat, and the collisional dissipation are derived from the gyrokinetic equation including the collision term and Maxwell equations. It is shown that, in the steady turbulence, the entropy produced by the turbulent transport fluxes is dissipated in part by collisions in the nonzonal-mode region and in part by those in the zonal-mode region after the nonlinear entropy transfer from nonzonal to zonal modes.

  20. Observation of the temporal Bragg-diffraction-induced laser-pulse splitting in a linear photonic crystal

    NASA Astrophysics Data System (ADS)

    Svyakhovskiy, S. E.; Kompanets, V. O.; Maydykovskiy, A. I.; Murzina, T. V.; Chekalin, S. V.; Skorynin, A. A.; Bushuev, V. A.; Mantsyzov, B. I.

    2012-07-01

    Temporal Bragg-diffraction-induced laser-pulse splitting into two pulses propagating with different group velocities is observed in multilayered linear photonic crystals (PCs). This phenomenon originates from spatially inhomogeneous light localization within the PCs at the Laue scheme of the dynamical Bragg diffraction. In a homogeneous medium at the PC output each pulse is spatially separated into two pulses, propagating in the transmission and diffraction directions, respectively. The experiments are carried out for a one-dimensional porous silicon-based PC consisting of 375 spatial periods of 800 nm thickness using a femtosecond Ti:sapphire laser as a probe. A linear dependence of the time splitting of each pair of transmitted and diffractively reflected pulses on the crystal thickness is demonstrated and is supported by theoretical estimations.

  1. Thermal-independent properties of PIN-PMN-PT single-crystal linear-array ultrasonic transducers.

    PubMed

    Chen, Ruimin; Wu, Jinchuan; Ho Lam, Kwok; Yao, Liheng; Zhou, Qifa; Tian, Jian; Han, Pengdi; Shung, K Kirk

    2012-12-01

    In this paper, low-frequency 32-element linear-array ultrasonic transducers were designed and fabricated using both ternary Pb(In(1/2)Nb(1/2))-Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PIN-PMN-PT) and binary Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PMNPT) single crystals. Performance of the array transducers was characterized as a function of temperature ranging from room temperature to 160°C. It was found that the array transducers fabricated using the PIN-PMN-PT single crystal were capable of satisfactory performance at 160°C, having a -6-dB bandwidth of 66% and an insertion loss of 37 dB. The results suggest that the potential of PIN-PMN-PT linear-array ultrasonic transducers for high-temperature ultrasonic transducer applications is promising. PMID:23221227

  2. Zirconium tungstate hydroxide hydrate revisited: Crystallization dependence on halide and hydronium ions

    SciTech Connect

    Colin, Julie A. Camper, DeMarco V.; Gates, Stacy D.; Simon, Monty D. Witker, Karen L. Lind, Cora

    2007-12-15

    The formation of zirconium tungstate hydroxide hydrate, a precursor to the negative thermal expansion material cubic zirconium tungstate, shows a strong dependence on hydrothermal reaction conditions. It was found that not only the acid concentration, but also the acid counterion plays a significant role in the crystallization of ZrW{sub 2}O{sub 7}(OH){sub 2}.2H{sub 2}O. High temperatures, high acid concentrations, and the presence of chloride or bromide ions promote the formation of well-crystallized ZrW{sub 2}O{sub 7}(OH){sub 2}.2H{sub 2}O. For low acid concentrations, a new zirconium tungstate hydrate polymorph is observed, which transforms to tetragonal ZrW{sub 2}O{sub 7}(OH){sub 2}.2H{sub 2}O at longer reaction times. A study of crystallization kinetics in hydrochloric acid is presented. - Graphical abstract: The formation of ZrW{sub 2}O{sub 7}(OH){sub 2}.2H{sub 2}O shows a strong dependence on reaction conditions. Both acid concentration and acid counterion play a significant role in the crystallization. High temperatures, high acid concentrations, and the presence of chloride or bromide ions promote the formation of well-crystallized ZrW{sub 2}O{sub 7}(OH){sub 2}.2H{sub 2}O. For low acid concentrations, a new zirconium tungstate hydrate polymorph is observed.

  3. Superharmonic resonances in a two-dimensional non-linear photonic-crystal nano-electro-mechanical oscillator

    NASA Astrophysics Data System (ADS)

    Chowdhury, A.; Yeo, I.; Tsvirkun, V.; Raineri, F.; Beaudoin, G.; Sagnes, I.; Raj, R.; Robert-Philip, I.; Braive, R.

    2016-04-01

    We investigate the non-linear mechanical dynamics of a nano-optomechanical mirror formed by a suspended membrane pierced by a photonic crystal. By applying to the mirror a periodic electrostatic force induced by interdigitated electrodes integrated below the membrane, we evidence superharmonic resonances of our nano-electro-mechanical system; the constant phase shift of the oscillator across the resonance tongues is observed on the onset of principal harmonic and subharmonic excitation regimes.

  4. Linkage Determination of Linear Oligosaccharides by MSn (n > 2) Collision-Induced Dissociation of Z1 Ions in the Negative Ion Mode

    NASA Astrophysics Data System (ADS)

    Konda, Chiharu; Bendiak, Brad; Xia, Yu

    2013-12-01

    Obtaining unambiguous linkage information between sugars in oligosaccharides is an important step in their detailed structural analysis. An approach is described that provides greater confidence in linkage determination for linear oligosaccharides based on multiple-stage tandem mass spectrometry (MSn, n >2) and collision-induced dissociation (CID) of Z1 ions in the negative ion mode. Under low energy CID conditions, disaccharides 18O-labeled on the reducing carbonyl group gave rise to Z1 product ions (m/z 163) derived from the reducing sugar, which could be mass-discriminated from other possible structural isomers having m/z 161. MS3 CID of these m/z 163 ions showed distinct fragmentation fingerprints corresponding to the linkage types and largely unaffected by sugar unit identities or their anomeric configurations. This unique property allowed standard CID spectra of Z1 ions to be generated from a small set of disaccharide samples that were representative of many other possible isomeric structures. With the use of MSn CID (n = 3 - 5), model linear oligosaccharides were dissociated into overlapping disaccharide structures, which were subsequently fragmented to form their corresponding Z1 ions. CID data of these Z1 ions were collected and compared with the standard database of Z1 ion CID using spectra similarity scores for linkage determination. As the proof-of-principle tests demonstrated, we achieved correct determination of individual linkage types along with their locations within two trisaccharides and a pentasaccharide.

  5. Temperature dependence of the luminescence spectra of garnet crystals doped with chromium ions

    NASA Astrophysics Data System (ADS)

    Orucu, Humeyra; Ozen, Gonul; Collins, John; Di Bartolo, Baldassare

    2009-05-01

    We have investigated the spectral behavior of a number of garnet crystals doped with chromium ions in a range of temperatures from 25 to 800 K. The crystals we considered are, in order of decreasing crystalline field, Y3Al5O12 (YAG), Gd3Ga5O12 (GGG) and Gd3Sc2Ga3O12 (GSGG). By investigating their luminescence spectra, including their vibronic spectra, over a very broad range of temperatures, we attempt to obtain a fuller picture of the processes following excitation.

  6. Spectroscopic detection and state preparation of a single praseodymium ion in a crystal.

    PubMed

    Utikal, T; Eichhammer, E; Petersen, L; Renn, A; Götzinger, S; Sandoghdar, V

    2014-01-01

    The narrow optical transitions and long spin coherence times of rare earth ions in crystals make them desirable for a number of applications ranging from solid-state spectroscopy and laser physics to quantum information processing. However, investigations of these features have not been possible at the single-ion level. Here we show that the combination of cryogenic high-resolution laser spectroscopy with optical microscopy allows one to spectrally select individual praseodymium ions in yttrium orthosilicate. Furthermore, this spectral selectivity makes it possible to resolve neighbouring ions with a spatial precision of the order of 10 nm. In addition to elaborating on the essential experimental steps for achieving this long-sought goal, we demonstrate state preparation and read out of the three ground-state hyperfine levels, which are known to have lifetimes of the order of hundred seconds. PMID:24722142

  7. Pulse height decrease in a single-crystal CVD diamond detector under gold ion beam bombardment

    NASA Astrophysics Data System (ADS)

    Sato, Yuki; Murakami, Hiroyuki

    2015-09-01

    A charged-particle detector was fabricated using a single-crystal diamond grown by chemical vapor deposition to examine its radiation hardness under heavy-ion bombardment. The irradiation dose dependence of the output pulse height from the diamond detector during gold ion beam bombardment at an energy of 7 MeV was investigated. The pulse height of output signals decreased with increasing amount of gold ion irradiation, and the pulse height was not recovered after applying a reverse-bias voltage. In addition, although only small amounts of vacancy and charge density generation inside the diamond detector were estimated and were found to be less than those in the Si detector by the Monte Carlo simulation of the Stopping and Range of Ions in Matter, the diamond detector did not show superior radiation hardness to the Si charged-particle detector.

  8. Crystalline perfection, optical and third harmonic generation analyses of non-linear optical single crystal of L-lysine acetate

    NASA Astrophysics Data System (ADS)

    Rani, Neelam; Vijayan, N.; Thukral, Kanika; Maurya, K. K.; Haranath, D.; Bhagavannarayana, G.; Verma, S.; Wahab, M. A.

    2013-03-01

    The potential organic non-linear optical single crystal of L-lysine acetate has been grown by slow evaporation solution growth technique (SEST) at room temperature. It crystallizes in the monoclinic system with space group of P21. The crystalline perfection of the grown single crystal has been examined by high resolution X-ray diffraction analysis (HRXRD). The functional groups of the synthesized compound have been identified by 13C NMR, 1H NMR and FTIR analyses. The optical absorption studies show that the crystal is transparent in the entire visible region with a cut-off wavelength of 236 nm. The optical band gap is found to be 5.29 eV. The steady-state PL spectra was recorded for pure L-lysine acetate crystal at room temperature. The third harmonic generation efficiency of the crystal has been evaluated by Z-scan technique and its non-linear optical coefficient has been calculated. Birefringence measurement has been carried out in order to see the optical homogeneity of the grown specimen. Its electrical properties has been assessed by dielectric measurement at different temperatures. The calculated optical band gap is 5.29 eV. Its thermal parameters like thermal diffusivity (α), thermal effusivity (e), thermal conductivity (k) and heat capacity (Cp) have been determined by photopyroelectric technique. Vickers micro hardness studies were carried out using a Vickers hardness tester equipped with a diamond square indenter. The piezoelectric measurement for L-lysine acetate has been also been carried at ambient condition.

  9. Ion-beam-induced epitaxial crystallization of implanted and chemical vapor deposited amorphous silicon

    NASA Astrophysics Data System (ADS)

    La Ferla, A.; Priolo, F.; Spinella, C.; Rimini, E.; Baroetto, F.; Ferla, G.

    1989-03-01

    The dependence of ion-beam enhanced epitaxial growth of amorphous Si layers on impurities either dissolved in the film or present at the film-substrate interface is considered. In the case of ion implanted layers, electrically active dopants, like B, P, As at concentrations above 1 × 10 20/cm 3, enhance the rate by a factor of 2 with respect to the undoped layer. The enhancement shows also a weak dependence on the dopant concentration. Inert impurities, like Ar, which prevent pure thermal regrowth, do not show any appreciable influence on the ion-beam-induced growth rate. Chemical vapor deposited Si layers with a thin native interfacial oxide layer can also be epitaxially regrown under ion irradiation. A critical fluence is needed before the interfacial oxide breaks down and broadens, allowing the epitaxial crystallization to take place. This process is characterized by an activation energy of 0.44 eV. The complex phenomenon of ion-beam-induced crystallization involves a dynamical interaction between production and annealing of point defects. The presence of electrically active dopants probably influences the lifetime of point defects. Impurities which prevent thermal regrowth are instead dissolved by ballistic effects and/or radiation-enhanced mixing.

  10. Crystallization effects and diamond formation in amorphous carbon films under low energy ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Patsalas, P.; Logothetidis, S.

    2001-05-01

    The crystallization effects occurring in various types of amorphous carbon (a-C) thin films with different structure and bonding induced by post-growth low energy (<1.5 keV) Ar + ion beam irradiation are presented. Detailed X-ray diffraction (XRD) measurements were used to identify several allotropic forms of carbon such as graphite and diamond as well as SiC detected in a-C films after ion irradiation. The diamond and SiC nucleation occurs close to the a-C/Si interface, beyond the ion penetration depth suggesting a non-direct nucleation mechanism. The relative content, grain size, distribution and orientation of each particular crystalline phase in the films depend strongly on the microstructural characteristics of the as-grown films. We also consider the effects of ion energy and fluence and substrate material on the crystallization process in an effort to get a deeper insight of the fundamental mechanisms occurring during the interaction of various carbon materials with low energy ion beams.

  11. Optical waveguides in Yb:SBN crystals fabricated by swift C3+ ion irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Guiyuan; Dong, Ningning; Wang, Jun; Akhmadaliev, Shavkat; Zhou, Shengqiang; Chen, Feng

    2016-01-01

    We report on the fabrication of optical planar waveguides supporting both the TE and TM confinements in Yb:SBN crystal by swift C3+ ions irradiation. A combination of the micro-photoluminescence and micro-Raman investigations have evidenced the presence of lattice distortion, damage and disordering of the SBN network along the ion irradiation path, with these effects being at the basis of the refractive index modification. The enhanced micro-photoluminescence and micro-Raman intensity in the waveguide volumes show the potential application of the obtained waveguides as active laser gain media.

  12. Optical planar waveguide in magnesium aluminate spinel crystal using oxygen ion implantation

    NASA Astrophysics Data System (ADS)

    Song, Hong-Lian; Yu, Xiao-Fei; Zhang, Lian; Wang, Tie-Jun; Qiao, Mei; Liu, Peng; Zhao, Jin-Hua; Wang, Xue-Lin

    2015-07-01

    A planar optical waveguide in MgAl2O4 crystal sample was fabricated using 6.0 MeV oxygen ion implantation at a fluence of 1.5 × 1015 ions/cm2 at room temperature. The optical modes were measured at a wavelength of 633 nm using a model 2010 prism coupler. The near-field intensity files in the visible band were measured and simulated with end-face coupling and FD-BPM methods, respectively. The absorption spectra show that the implantation process has almost no effect on the visible and near-infrared band absorption.

  13. Ranges and profiles of distribution of low-energy ions channeling in metal and semiconductor single crystals

    NASA Astrophysics Data System (ADS)

    Umarov, F. F.; Rasulov, A. M.; Khaidarov, A. K.

    2003-07-01

    In the present work peculiarities of trajectories and energy losses, ranges and profiles of distribution of low-energy different-mass ions channeling in thin single crystals of metals and semiconductors have been thoroughly studied by computer simulation in binary collision approximation. The character of oscillations of channeled-ion trajectories depending on their energies, aiming points from the axis of a channel, kind of interaction potential, crystal lattice type and temperature has been determined. It has been found that, in the case of light ions even at low energy, the main contribution to energy loss is made by inelastic energy losses, whereas for heavy ions, already at E < 10 keV elastic energy losses exceed inelastic ones. Profiles of the distribution of channeled ions have been calculated depending on crystal lattice type, kind of ions and their energy.

  14. Quantitative analysis with advanced compensated polarized light microscopy on wavelength dependence of linear birefringence of single crystals causing arthritis

    NASA Astrophysics Data System (ADS)

    Takanabe, Akifumi; Tanaka, Masahito; Taniguchi, Atsuo; Yamanaka, Hisashi; Asahi, Toru

    2014-07-01

    To improve our ability to identify single crystals causing arthritis, we have developed a practical measurement system of polarized light microscopy called advanced compensated polarized light microscopy (A-CPLM). The A-CPLM system is constructed by employing a conventional phase retardation plate, an optical fibre and a charge-coupled device spectrometer in a polarized light microscope. We applied the A-CPLM system to measure linear birefringence (LB) in the visible region, which is an optical anisotropic property, for tiny single crystals causing arthritis, i.e. monosodium urate monohydrate (MSUM) and calcium pyrophosphate dihydrate (CPPD). The A-CPLM system performance was evaluated by comparing the obtained experimental data using the A-CPLM system with (i) literature data for a standard sample, MgF2, and (ii) experimental data obtained using an established optical method, high-accuracy universal polarimeter, for the MSUM. The A-CPLM system was found to be applicable for measuring the LB spectra of the single crystals of MSUM and CPPD, which cause arthritis, in the visible regions. We quantitatively reveal the large difference in LB between MSUM and CPPD crystals. These results demonstrate the usefulness of the A-CPLM system for distinguishing the crystals causing arthritis.

  15. Growth, structural and optical studies on mixed glycine nitrate (d-GBC) crystals of non linear optical origin

    NASA Astrophysics Data System (ADS)

    Dongare, Shailesh S.; Patil, S. B.; Khandpekar, M. M.

    2015-06-01

    A semi organic crystal of mixed amino-nitrate d-GBC having non linear optical characteristics has been grown from solution by slow evaporation technique at room temperature. Transparent crystals (11 × 9 × 4 mm3) have been obtained in 3-4 weeks time. The solubility of d-GBC has been determined in water. The new d-GBC crystals have been characterized by powder XRD, FTIR and UV Spectra. The grown crystal belongs to orthorhombic system with cell parameters a=8.110 A.U, b=17.666 A.U, c=7.476 A.U and unit cell volume of 1071.14 A.U3. The presence of fundamental groups has been verified. A wide transparency window useful for optoelectronic applications is indicated by the UV Studies. The optical second harmonic generation conversion efficiency of d-GBC using characteristic 1064nm Nd-YAG laser (Kurtz and Perry method) is found to be 0.919 times that of KDP. Vickers Microhardness studies shows work hardening coefficient (n= 4.23) indicating soft category of Crystals.

  16. Heavy-ion injector based on an electron cyclotron ion source for the superconducting linear accelerator of the Rare Isotope Science Project

    NASA Astrophysics Data System (ADS)

    Hong, In-Seok; Kim, Yong-Hwan; Choi, Bong-Hyuk; Choi, Suk-Jin; Park, Bum-Sik; Jin, Hyun-Chang; Kim, Hye-Jin; Heo, Jeong-Il; Kim, Deok-Min; Jang, Ji-Ho

    2016-02-01

    The injector for the main driver linear accelerator of the Rare Isotope Science Project in Korea, has been developed to allow heavy ions up to uranium to be delivered to the inflight fragmentation system. The critical components of the injector are the superconducting electron cyclotron resonance (ECR) ion sources, the radio frequency quadrupole (RFQ), and matching systems for low and medium energy beams. We have built superconducting magnets for the ECR ion source, and a prototype with one segment of the RFQ structure, with the aim of developing a design that can satisfy our specifications, demonstrate stable operation, and prove results to compare the design simulation.

  17. Heavy-ion injector based on an electron cyclotron ion source for the superconducting linear accelerator of the Rare Isotope Science Project.

    PubMed

    Hong, In-Seok; Kim, Yong-Hwan; Choi, Bong-Hyuk; Choi, Suk-Jin; Park, Bum-Sik; Jin, Hyun-Chang; Kim, Hye-Jin; Heo, Jeong-Il; Kim, Deok-Min; Jang, Ji-Ho

    2016-02-01

    The injector for the main driver linear accelerator of the Rare Isotope Science Project in Korea, has been developed to allow heavy ions up to uranium to be delivered to the inflight fragmentation system. The critical components of the injector are the superconducting electron cyclotron resonance (ECR) ion sources, the radio frequency quadrupole (RFQ), and matching systems for low and medium energy beams. We have built superconducting magnets for the ECR ion source, and a prototype with one segment of the RFQ structure, with the aim of developing a design that can satisfy our specifications, demonstrate stable operation, and prove results to compare the design simulation. PMID:26931946

  18. Swift Heavy Ion Beam Modified Behaviour of Pure and Doped TGS Crystals

    SciTech Connect

    Bajpai, P. K.

    2009-03-10

    Modifications due to swift heavy ion (SHI) beam irradiation on polar surfaces of pure and doped tri-glycine sulphate (TGS) crystals are investigated using dielectric, ferroelectric, optical and scanning force microcopy with varying ion beam fluence. The dielectric response becomes diffuse and the loss decreases, the optical band gap gets modified, the surface micro-relief's show pits and protrusions converting into regular hillocks of nano-dimensions. The results are interpreted considering that irradiation takes the crystal to a non-equilibrium state and generates thermal/charge flux leading to thermally generated internal field. The micro-relief is explained as a result of domain orientation; piezoelectric compression and stretching creating inhomogeneous force gradient at domain walls.

  19. Comprehensive Spectroscopic Determination of the Crystal Field Splitting in an Erbium Single-Ion Magnet.

    PubMed

    Rechkemmer, Yvonne; Fischer, Julia E; Marx, Raphael; Dörfel, María; Neugebauer, Petr; Horvath, Sebastian; Gysler, Maren; Brock-Nannestad, Theis; Frey, Wolfgang; Reid, Michael F; van Slageren, Joris

    2015-10-14

    The electronic structure of a novel lanthanide-based single-ion magnet, {C(NH2)3}5[Er(CO3)4]·11H2O, was comprehensively studied by means of a large number of different spectroscopic techniques, including far-infrared, optical, and magnetic resonance spectroscopies. A thorough analysis, based on crystal field theory, allowed an unambiguous determination of all relevant free ion and crystal field parameters. We show that inclusion of methods sensitive to the nature of the lowest-energy states is essential to arrive at a correct description of the states that are most relevant for the static and dynamic magnetic properties. The spectroscopic investigations also allowed for a full understanding of the magnetic relaxation processes occurring in this system. Thus, the importance of spectroscopic studies for the improvement of single-molecule magnets is underlined. PMID:26394012

  20. Waveguiding properties in Yb:YAG crystals implanted with protons and carbon ions.

    PubMed

    Vázquez, G V; Ramírez, D; Márquez, H; Flores-Romero, E; Rickards, J; Trejo-Luna, R

    2012-08-01

    We report the fabrication and analysis of optical waveguides in Yb:YAG crystals using either proton or carbon ion implantation. Planar waveguides were obtained by implanting the whole surface of the crystals. Channel waveguides were defined using an electroformed mask with apertures of 10, 15, and 20 micrometers in width. The waveguiding properties of the structures were analyzed, showing good light confinement based on the transversal mode distribution and optical transmission measurements. The spectroscopic properties of the Yb ions in the YAG host are preserved after the implantation process, which demonstrates the potential of this technique for tailoring microcomponents for integrated optics applications. In particular, the Yb:YAG waveguides have the potential to operate as miniature lasers. PMID:22859050

  1. Smoothing metallic glasses without introducing crystallization by gas cluster ion beam

    SciTech Connect

    Shao, Lin; Chen, Di; Myers, Michael; Wang, Jing; Tilakaratne, Buddhi; Wijesundera, Dharshana; Chu, Wei-Kan; Xie, Guoqiang; Zare, Arezoo; Lucca, Don A.

    2013-03-11

    We show that 30 keV Ar cluster ion bombardment of Ni{sub 52.5}Nb{sub 10}Zr{sub 15}Ti{sub 15}Pt{sub 7.5} metallic glass (MG) can remove surface mountain-like features and reduce the root mean square surface roughness from 12 nm to 0.7 nm. X-ray diffraction analysis reveals no crystallization after cluster ion irradiation. Molecular dynamics simulations show that, although damage cascades lead to local melting, the subsequent quenching rate is a few orders of magnitude higher than the critical cooling rate for MG formation, thus the melted zone retains its amorphous nature down to room temperature. These findings can be applied to obtain ultra-smooth MGs without introducing crystallization.

  2. Scanning-force-microscopy study of MeV-atomic-ion-induced surface tracks in organic crystals

    SciTech Connect

    Kopniczky, J.; Reimann, C.T.; Hallen, A.; Sundqvist, B.U.R. ); Tengvall, P.; Erlandsson, R. )

    1994-01-01

    We present scanning force microscope images of craterlike defects induced by individual 78.2-MeV [sup 127]I ions incident on organic single-crystal [ital L]-valine surfaces. For grazing incidence ions, the craters are elongated along the ion azimuth of incidence and display a raised tail in the surface above the ion track. This permanent plastic deformation of the surface indicates that a hydrodynamic pressure-pulse phenomenon occurs in response to the electronically deposited energy.

  3. Unidirectional growth, rocking curve, linear and nonlinear optical properties of LPHCl single crystals

    NASA Astrophysics Data System (ADS)

    Kumar, P. Ramesh; Gunaseelan, R.; Raj, A. Antony; Selvakumar, S.; Sagayaraj, P.

    2012-06-01

    Nonlinear optical amino-acid single crystal of L-phenylalanine hydrochloride (LPHCl) was successfully grown by unidirectional Sankaranarayanan-Ramasamy (SR) method under ambient conditions for the first time. The grown single crystal was subjected to different characterization analyses in order to find out its suitability for device fabrication. The crystalline perfection was evaluated using high-resolution X-ray diffractometry. It is evident from the optical absorption study that crystal has excellent transmission in the entire visible region with its lower cut off wavelength around 290 nm.

  4. Suppressing gate errors through extra ions coupled to a cavity in frequency-domain quantum computation using rare-earth-ion-doped crystal

    NASA Astrophysics Data System (ADS)

    Nakamura, Satoshi; Goto, Hayato; Kujiraoka, Mamiko; Ichimura, Kouichi; Quantum Computer Team

    The rare-earth-ion-doped crystals, such as Pr3+: Y2SiO5, are promising materials for scalable quantum computers, because the crystals contain a large number of ions which have long coherence time. The frequency-domain quantum computation (FDQC) enables us to employ individual ions coupled to a common cavity mode as qubits by identifying with their transition frequencies. In the FDQC, operation lights with detuning interact with transitions which are not intended to operate, because ions are irradiated regardless of their positions. This crosstalk causes serious errors of the quantum gates in the FDQC. When ``resonance conditions'' between eigenenergies of the whole system and transition-frequency differences among ions are satisfied, the gate errors increase. Ions for qubits must have transitions avoiding the conditions for high-fidelity gate. However, when a large number of ions are employed as qubits, it is difficult to avoid the conditions because of many combinations of eigenenergies and transitions. We propose new implementation using extra ions to control the resonance conditions, and show the effect of the extra ions by a numerical simulation. Our implementation is useful to realize a scalable quantum computer using rare-earth-ion-doped crystal based on the FDQC.

  5. Optical properties of Dy3+ ion in PbF2 laser crystal

    NASA Astrophysics Data System (ADS)

    Chen, G. Z.; Yin, J. G.; Zhang, L. H.; He, M. Z.; Ma, E.; Ning, K. J.; Zhang, P. X.; Liu, Y. C.; Hang, Y.

    2013-11-01

    High-quality Dy:PbF2 crystal is grown by the Bridgman method in a nonvacuum atmosphere. By measuring the area under absorption bands, the experimental oscillator strengths are determined. The Judd-Ofelt (JO) intensity parameters Ωλ (λ = 2, 4, 6) are evaluated by the least-squares fit method. These phenomenological parameters are used to predict radiative transition probabilities, radiative lifetime and branching ratios for various excited levels of the Dy3+:PbF2 crystal. Photoluminescence spectra and lifetime of 6H13/2 levels of the Dy3+ ions have been measured. The laser transitions with most potential are identified and the utility of the PbF2 crystal as laser active material is discussed.

  6. Low-crystallized carbon materials for lithium-ion secondary batteries

    NASA Astrophysics Data System (ADS)

    Higuchi, Hayato; Uenae, Keiichiro; Kawakami, Akira

    The charge/discharge characteristics and mechanisms of low-crystallized carbons which have larger capacity than graphite have been investigated. Low-crystallized carbons have two principal types of charge curve versus Li metal. Hard carbons prepared at 1100 °C (H11) show charge curves with a low average potential, whereas soft carbons pyrolyzed at 700 °C (S7) show those with a high average potential. These results might depend on the lithium diffusion rate in their non-crystallized sites. The 18650-type Li-ion batteries using H11 have comparable capacity versus graphite, whereas the batteries using S7 have low capacity because of their low charge/discharge efficiency.

  7. First crystal structures of Na+,K+-ATPase: new light on the oldest ion pump.

    PubMed

    Toyoshima, Chikashi; Kanai, Ryuta; Cornelius, Flemming

    2011-12-01

    Na(+),K(+)-adenosine triphosphatase (NKA) is the first P-type ion translocating adenosine triphosphatase (ATPase) ever identified, and the significance of this class of proteins was highlighted by the 1997 Nobel Prize in Chemistry awarded to Jens C. Skou for the discovery in 1957. More than half a century passed between the initial identification and the publication of a high-resolution crystal structure of NKA. Although the new crystal structures provided many surprises and insights, structural biology on this system remains challenging, as NKA is a very difficult protein to crystallize. Here we explain the reasons behind the challenges, introduce a mechanism that governs the function, and summarize current knowledge of NKA structure in comparison with another member of the P-type ATPase family, Ca(2+)-ATPase. PMID:22153495

  8. Evolution of surface modification by Ar+ ion implantation with incident angle into sodium potassium niobate single crystal

    NASA Astrophysics Data System (ADS)

    Saravanan, R.; Rajesh, D.; Rajasekaran, S. V.; Perumal, R.; Chitra, M.; Jayavel, R.

    2013-06-01

    Single crystals of sodium potassium niobate (K0.5Na0.5)NbO3 (KNN) were grown by flux method and crystals were implantation with 100 keV Ar+ ions with 1016 ions/cm2 fluencies at various incident angles. Evolution of Ar+ ion impact on surface of KNN samples has been ascertained by optical microscope and Atomic force microscope. Varying the incident angle more varied surface features are observed. The results show that the Elongated surface defects only are observed in the ion impact direction at an angle of θ = 30° and 60°.

  9. Investigations on the vibrational modes and non-linear optical properties of 4-Fluoro Chalcone crystal

    NASA Astrophysics Data System (ADS)

    Prabu, S.; Nagalakshmi, R.; Balaji, J.; Srinivasan, P.

    2014-08-01

    Organic Nonlinear Optical (NLO) crystals of 4-fluorochalcone (4FC) were synthesized and grown by slow evaporation solution growth method. The grown crystals have been characterised by powder X-ray diffraction, factor group analysis, FTIR, FT-Raman, UV-Vis Spectroscopy, powder SHG and Vickers microhardness tests. Theoretical quantum chemical analysis were performed to determine the first order hyperpolarizability (β) and HOMO-LUMO analysis of the title compound were computed by GAUSSIAN 03 package.

  10. EPR study of Cu2+ ion doped orotato(nicotinamid)cobalt(II) single crystal

    NASA Astrophysics Data System (ADS)

    Yıldırım, İ.; Karabulut, B.; Büyükgüngör, O.

    2016-01-01

    We have studied the Cu2+ ion doped orotato(nicotinamid)cobalt(II) complex by using EPR spectroscopy and X-ray diffraction. The single crystal is triclinic with the space group P 1 ‾ . The unit cell dimensions of the crystal are a = 7.2785(4) Å, b = 10.2349(5) Å, c = 12.7372(6) Å, α = 69.297(4)°, β = 74.791(4)° and γ = 76.995(4)°, with Z = 2. We analyzed the EPR spectra of both single crystal and powder of the complex at room temperature. EPR analysis indicates the presence of only one Cu2+ site. We obtained the spin Hamiltonian parameters from the single crystal data for the complex. The spin Hamiltonian parameters are gx = 2.032, gy = 2.116, gz = 2.319, Ax = 28 G, Ay = 66 G, Az = 126 G. These data indicate that the symmetry of paramagnetic center is rhombic. We constructed the ground state wave function of the Cu2+ ion.

  11. Optical planar waveguide in sodium-doped calcium barium niobate crystals by carbon ion implantation

    NASA Astrophysics Data System (ADS)

    Zhao, Jin-Hua; Qin, Xi-Feng; Wang, Feng-Xiang; Fu, Gang; Wang, Hui-Lin; Wang, Xue-Lin

    2013-07-01

    There is great interest in niobate crystals which belong to the tetragonal tungsten bronze (TTB) families owing to their intriguing properties. As one representative of such crystals, CBN (calcium barium niobate) has attracted rapidly growing attention. Because it has a higher Curie temperature than SBN (strontium barium niobate), possesses outstanding ferroelectric and it possesses optical properties. In addition, doped with sodium, CBN will show a higher Curie temperature than pure CBN. We report on the fabrication and characterization of optical planar waveguide in x-cut sodium-doped calcium barium niobate crystal by using C ion implantation. The guided-mode properties at the wavelength of 633 and 1539 nm are investigated through prism-coupling measurements, respectively. By applying direct end-face coupling arrangement, the near-field optical intensity distribution of waveguide modes is measured at 633 nm. For comparison, the modal profile of the same guided mode is also numerically calculated by the finite difference beam-propagation method via computer software BeamPROP. The transmission spectra of the waveguide before and after ion implantation treatments were investigated also. Our experiment results reveal that the waveguide could propagate light with transverse magnetic polarized direction only and it is assumed that the polarization selectivity of CBN crystal may responsible for this phenomenon.

  12. Hydrothermal crystallization of α-alumina monohydrate in the presence of copper ions

    NASA Astrophysics Data System (ADS)

    Brown, N.

    1989-09-01

    The effect of copper ions on the hydrothermal crystallization of α-alumina monohydrate (A1OOH, mineral name boehmite), following oxidation of the organic carbon compounds in sodium aluminate solution of the Bayer process, has been examined using scanning electron microscopy and particle size analyses. The initial effect of the copper ions on the homogeneously nucleated α-alumina monohydrate is to inhibit crystal growth on the (001) faces and direct the growth process to the prismatic faces of the rhombic or diamond shaped crystals. At low copper levels (up to 0.1 wt% in α-alumina monohydrate), this leads to the formation of plate-like crystals up to 25 μm in size which can intergrow and develop into particles with an average size of up to 100 μm. The size and structure of the μ-alumina monohydrate particles, however, depend on the amount of copper present and increasing copper levels (up to 1.0 wt%) lead progressively to a decrease in average particle size of α-alumina monohydrate to about 10 μm and the formation of more rounded oblong-shaped particles having a compact sheaf-like structure. Copper-containing α-alumina monohydrate particles of this size and form can be readily recovered from the oxidized liquor and recycled in the industrial process.

  13. EPR study of Cu(2+) ion doped orotato(nicotinamid)cobalt(II) single crystal.

    PubMed

    Yıldırım, I; Karabulut, B; Büyükgüngör, O

    2016-01-01

    We have studied the Cu(2+) ion doped orotato(nicotinamid)cobalt(II) complex by using EPR spectroscopy and X-ray diffraction. The single crystal is triclinic with the space group P1‾. The unit cell dimensions of the crystal are a=7.2785(4)Å, b=10.2349(5)Å, c=12.7372(6)Å, α=69.297(4)°, β=74.791(4)° and γ=76.995(4)°, with Z=2. We analyzed the EPR spectra of both single crystal and powder of the complex at room temperature. EPR analysis indicates the presence of only one Cu(2+) site. We obtained the spin Hamiltonian parameters from the single crystal data for the complex. The spin Hamiltonian parameters are gx=2.032, gy=2.116, gz=2.319, Ax=28G, Ay=66G, Az=126G. These data indicate that the symmetry of paramagnetic center is rhombic. We constructed the ground state wave function of the Cu(2+) ion. PMID:25704568

  14. Cation and anion transport in a dicationic imidazolium-based plastic crystal ion conductor.

    PubMed

    Kidd, Bryce E; Lingwood, Mark D; Lee, Minjae; Gibson, Harry W; Madsen, Louis A

    2014-02-27

    Here we investigate the organic ionic plastic crystal 1,2-bis[N-(N'-hexylimidazolium-d2(4,5))]ethane 2PF6(-) in one of its solid plastic crystal phases by means of multinuclear solid-state (SS) NMR and pulsed-field-gradient NMR diffusometry. We quantify distinct cation and anion diffusion coefficients as well as the Arrhenius diffusion activation energies (Ea) in this dicationic imidazolium-based plastic crystal. Our studies suggest a change in transport mechanism for the cation upon varying thermal and magnetic treatment (9.4 T), evidenced by differences in cation and anion Ea. Moreover, variable temperature (2)H SSNMR line shapes support a change in local molecular environment upon slow cooling in B0. We quantify the percentage of mobile anions as a function of temperature with (19)F SSNMR, wherein two distinct spectral features are present. We also comment on the Arrhenius pre-exponential factor for diffusion (D0), giving insight into the number of degrees of freedom for transport for both cation and anion as a function of thermal treatment. Given the breadth and depth of our measurements, we propose that bulk ion transport is dominated by anion diffusion in ionic-liquid-like domain boundaries separating crystallites. This study elucidates fundamental properties of this plastic crystal, and allows for a more general and deeper understanding of ion transport within such materials. PMID:24495282

  15. System for measuring temporal profiles of scintillation at high and different linear energy transfers by using pulsed ion beams

    SciTech Connect

    Koshimizu, Masanori Asai, Keisuke; Kurashima, Satoshi; Taguchi, Mitsumasa; Kimura, Atsushi; Iwamatsu, Kazuhiro

    2015-01-15

    We have developed a system for measuring the temporal profiles of scintillation at high linear energy transfer (LET) by using pulsed ion beams from a cyclotron. The half width at half maximum time resolution was estimated to be 1.5–2.2 ns, which we attributed mainly to the duration of the pulsed ion beam and timing jitter between the trigger signal and the arrival of the ion pulse. The temporal profiles of scintillation of BaF{sub 2} at different LETs were successfully observed. These results indicate that the proposed system is a powerful tool for analyzing the LET effects in temporal profiles of scintillation.

  16. Extending framework based on the linear coordination polymers: Alternative chains containing lanthanum ion and acrylic acid ligand

    SciTech Connect

    Li Hui . E-mail: lihui@bit.edu.cn; Guo Ming; Tian Hong; He Feiyue; Lee, G.-H.; Peng, S.-M.

    2006-11-15

    One-dimensional alternative chains of two lanthanum complexes: [La(L{sup 1}){sub 3}(CH{sub 3}OH)(H{sub 2}O){sub 2}].5H{sub 2}O (L{sup 1}=anion of {alpha}-cyano-4-hydroxycinnamic acid ) 1 and [La(L{sup 2}){sub 3}(H{sub 2}O){sub 2}].3H{sub 2}O (L{sup 2}=anion of trans-3-(4-methyl-benzoyl)-acrylic acid) 2 were synthesized and structurally characterized by single-crystal X-ray diffraction, element analysis, IR and thermogravimetric analysis. The crystal structure data are as follows for 1: C{sub 31}H{sub 36}LaN{sub 3}O{sub 17}, triclinic, P-1, a=9.8279(4)A, b=11.8278(5)A, c=17.8730(7)A, {alpha}=72.7960(10){sup o}, {beta}=83.3820(10){sup o}, {gamma}=67.1650(10)-bar , Z=2, R{sub 1}=0.0377, wR{sub 2}=0.0746; for 2: C{sub 33}H{sub 37}LaO{sub 14}, triclinic, P-1, a=8.7174(5)A, b=9.9377(5)A, c=21.153(2)A, {alpha}=81.145(2){sup o}, {beta}=87.591(2){sup o}, {gamma}=67.345(5){sup o}, Z=2, R{sub 1}=0.0869, wR{sub 2}=0.220. 1 is a rare example of the alternative chain constructed by syn-syn and anti-syn coordination mode of carboxylato ligand arranged along the chain alternatively. La(III) ions in 2 are linked by two {eta}{sup 3}-O bridges and four bridges (two {eta}{sup 2}-O and two {eta}{sup 3}-O) alternatively. Both of the linear coordination polymers grow into two- and three-dimensional networks by packing through extending hydrogen-bond network directed by ligands.

  17. Growth and EPR and optical properties of Li 2B 4O 7 single crystals doped with Co 2+ ions

    NASA Astrophysics Data System (ADS)

    Piwowarska, D.; Kaczmarek, S. M.; Berkowski, M.; Stefaniuk, I.

    2006-05-01

    Li 2B 4O 7 single crystals doped with Co ions were grown by the Czochralski method. The electron paramagnetic resonance (EPR) and optical absorption spectra of Li 2B 4O 7 (LBO) single crystals doped with Co 2+ ions were measured. The EPR spectra could be described by the spin-Hamiltonian with an effective spin of S={1}/{2} in octahedral symmetry. The values of g and A tensors and direction cosines characterizing Co 2+ centers in the LBO crystal were determined for the first time also. The EPR data reveals at least two types of Co 2+ centers. Optical absorption was measured in the range of 200 to 3200 nm for "as-grown" and γ-irradiated samples of Co:Li 2B 4O 7 crystals confirming octahedral coordination of Co 2+ ions and cation vacancies arising in the "as-grown" crystal.

  18. Rapid screening and characterization of drug metabolites using a new quadrupole-linear ion trap mass spectrometer.

    PubMed

    Hopfgartner, Gérard; Husser, Christophe; Zell, Manfred

    2003-02-01

    The application of a new hybrid RF/DC quadrupole-linear ion trap mass spectrometer to support drug metabolism and pharmacokinetic studies is described. The instrument is based on a quadrupole ion path and is capable of conventional tandem mass spectrometry (MS/MS) as well as several high-sensitivity ion trap MS scans using the final quadrupole as a linear ion trap. Several pharmaceutical compounds, including trocade, remikiren and tolcapone, were used to evaluate the capabilities of the system with positive and negative turbo ionspray, using either information-dependent data acquisition (IDA) or targeted analysis for the screening, identification and quantification of metabolites. Owing to the MS/MS in-space configuration, quadrupole-like CID spectra with ion trap sensitivity can be obtained without the classical low mass cutoff of 3D ion traps. The system also has MS(3) capability which allows fragmentation cascades to be followed. The combination of constant neutral loss or precursor ion scan with the enhanced product ion scan was found to be very selective for identifying metabolites at the picogram level in very complex matrices. Owing to the very high cycle time and, depending on the mass range, up to eight different MS experiments could be performed simultaneously without compromising chromatographic performance. Targeted product ion analysis was found to be complementary to IDA, in particular for very low concentrations. Comparable sensitivity was found in enhanced product ion scan and selected reaction monitoring modes. The instrument is particularly suitable for both qualitative and quantitative analysis. PMID:12577280

  19. Friction. Tuning friction atom-by-atom in an ion-crystal simulator.

    PubMed

    Bylinskii, Alexei; Gangloff, Dorian; Vuletić, Vladan

    2015-06-01

    Friction between ordered, atomically smooth surfaces at the nanoscale (nanofriction) is often governed by stick-slip processes. To test long-standing atomistic models of such processes, we implemented a synthetic nanofriction interface between a laser-cooled Coulomb crystal of individually addressable ions as the moving object and a periodic light-field potential as the substrate. We show that stick-slip friction can be tuned from maximal to nearly frictionless via arrangement of the ions relative to the substrate. By varying the ion number, we also show that this strong dependence of friction on the structural mismatch, as predicted by many-particle models, already emerges at the level of two or three atoms. This model system enables a microscopic and systematic investigation of friction, potentially even into the quantum many-body regime. PMID:26045432

  20. Tuning friction atom-by-atom in an ion-crystal simulator

    NASA Astrophysics Data System (ADS)

    Bylinskii, Alexei; Gangloff, Dorian; Vuletić, Vladan

    2015-06-01

    Friction between ordered, atomically smooth surfaces at the nanoscale (nanofriction) is often governed by stick-slip processes. To test long-standing atomistic models of such processes, we implemented a synthetic nanofriction interface between a laser-cooled Coulomb crystal of individually addressable ions as the moving object and a periodic light-field potential as the substrate. We show that stick-slip friction can be tuned from maximal to nearly frictionless via arrangement of the ions relative to the substrate. By varying the ion number, we also show that this strong dependence of friction on the structural mismatch, as predicted by many-particle models, already emerges at the level of two or three atoms. This model system enables a microscopic and systematic investigation of friction, potentially even into the quantum many-body regime.

  1. Zenithal alignment of liquid crystal on homeotropic polyimide film irradiated by ion beam.

    PubMed

    Choi, Yoonseuk; Yoon, Tae-Hoon; Kwon, Jin Hyuk; Yi, Jonghoon; Gwag, Jin Seog

    2012-01-01

    We investigate the pretilt characteristics of a nematic liquid crystal [LC] in terms of ion beam exposure conditions on the homeotropic polyimide alignment layer. The pretilt angle of LCs in the case of high-energy ion beam treatment was decreased considerably almost the same to that of the homogenous alignment layer though we used homeotropic polyimide film at first. Increasing irradiating energy, we could control the pretilt from 90° to 1° with several steps. We believe that this is because the side chain with hydrophobicity in the used polyimide is broken by ion beam exposure. To confirm it, contact angle measurement was carried out. With this result, we can easily control the LC pretilt in the pixel with appropriate exposure conditions which is critical to achieve excellent electrooptic characteristics and good image quality. PMID:22221956

  2. Zenithal alignment of liquid crystal on homeotropic polyimide film irradiated by ion beam

    PubMed Central

    2012-01-01

    We investigate the pretilt characteristics of a nematic liquid crystal [LC] in terms of ion beam exposure conditions on the homeotropic polyimide alignment layer. The pretilt angle of LCs in the case of high-energy ion beam treatment was decreased considerably almost the same to that of the homogenous alignment layer though we used homeotropic polyimide film at first. Increasing irradiating energy, we could control the pretilt from 90° to 1° with several steps. We believe that this is because the side chain with hydrophobicity in the used polyimide is broken by ion beam exposure. To confirm it, contact angle measurement was carried out. With this result, we can easily control the LC pretilt in the pixel with appropriate exposure conditions which is critical to achieve excellent electrooptic characteristics and good image quality. PMID:22221956

  3. Zenithal alignment of liquid crystal on homeotropic polyimide film irradiated by ion beam

    NASA Astrophysics Data System (ADS)

    Choi, Yoonseuk; Yoon, Tae-Hoon; Kwon, Jin Hyuk; Yi, Jonghoon; Gwag, Jin Seog

    2012-01-01

    We investigate the pretilt characteristics of a nematic liquid crystal [LC] in terms of ion beam exposure conditions on the homeotropic polyimide alignment layer. The pretilt angle of LCs in the case of high-energy ion beam treatment was decreased considerably almost the same to that of the homogenous alignment layer though we used homeotropic polyimide film at first. Increasing irradiating energy, we could control the pretilt from 90° to 1° with several steps. We believe that this is because the side chain with hydrophobicity in the used polyimide is broken by ion beam exposure. To confirm it, contact angle measurement was carried out. With this result, we can easily control the LC pretilt in the pixel with appropriate exposure conditions which is critical to achieve excellent electrooptic characteristics and good image quality.

  4. Swift heavy ion irradiation induced phase transformation in calcite single crystals

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    Ion irradiation induced phase transformation in calcite single crystals have been studied by means of Raman and infrared spectroscopy using 120 MeV Au 9+ ions. The observed bands have been assigned according to group theory analysis. For higher fluence of 5×10 12 ion/cm 2, an extra peak on either side of the 713 cm -1 peak and an increase in the intensity of 1085 cm -1 peak were observed in Raman studies. FTIR spectra exhibit extra absorption bands at 674, 1589 cm -1 and enhancement in bands at 2340 and 2374 cm -1 was observed. This might be due to the phase transformation from calcite to vaterite. The damage cross section ( σ) for all the Raman and FTIR active modes was determined. The increase of FWHM, shift in peak positions and appearance of new peaks indicated that calcite phase is converted into vaterite.

  5. Using support vector machines to improve elemental ion identification in macromolecular crystal structures

    DOE PAGESBeta

    Morshed, Nader; Echols, Nathaniel; Adams, Paul D.

    2015-04-25

    In the process of macromolecular model building, crystallographers must examine electron density for isolated atoms and differentiate sites containing structured solvent molecules from those containing elemental ions. This task requires specific knowledge of metal-binding chemistry and scattering properties and is prone to error. A method has previously been described to identify ions based on manually chosen criteria for a number of elements. Here, the use of support vector machines (SVMs) to automatically classify isolated atoms as either solvent or one of various ions is described. Two data sets of protein crystal structures, one containing manually curated structures deposited with anomalousmore » diffraction data and another with automatically filtered, high-resolution structures, were constructed. On the manually curated data set, an SVM classifier was able to distinguish calcium from manganese, zinc, iron and nickel, as well as all five of these ions from water molecules, with a high degree of accuracy. Additionally, SVMs trained on the automatically curated set of high-resolution structures were able to successfully classify most common elemental ions in an independent validation test set. This method is readily extensible to other elemental ions and can also be used in conjunction with previous methods based on a priori expectations of the chemical environment and X-ray scattering.« less

  6. Using support vector machines to improve elemental ion identification in macromolecular crystal structures

    SciTech Connect

    Morshed, Nader; Echols, Nathaniel; Adams, Paul D.

    2015-04-25

    In the process of macromolecular model building, crystallographers must examine electron density for isolated atoms and differentiate sites containing structured solvent molecules from those containing elemental ions. This task requires specific knowledge of metal-binding chemistry and scattering properties and is prone to error. A method has previously been described to identify ions based on manually chosen criteria for a number of elements. Here, the use of support vector machines (SVMs) to automatically classify isolated atoms as either solvent or one of various ions is described. Two data sets of protein crystal structures, one containing manually curated structures deposited with anomalous diffraction data and another with automatically filtered, high-resolution structures, were constructed. On the manually curated data set, an SVM classifier was able to distinguish calcium from manganese, zinc, iron and nickel, as well as all five of these ions from water molecules, with a high degree of accuracy. Additionally, SVMs trained on the automatically curated set of high-resolution structures were able to successfully classify most common elemental ions in an independent validation test set. This method is readily extensible to other elemental ions and can also be used in conjunction with previous methods based on a priori expectations of the chemical environment and X-ray scattering.

  7. Label-free liquid crystal biosensor based on specific oligonucleotide probes for heavy metal ions.

    PubMed

    Yang, Shengyuan; Wu, Chao; Tan, Hui; Wu, Yan; Liao, Shuzhen; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin

    2013-01-01

    In this study, to enhance the capability of metal ions disturbing the orientation of liquid crystals (LCs), we designed a new label-free LC biosensor for the highly selective and sensitive detection of heavy metal ions. This strategy makes use of the target-induced DNA conformational change to enhance the disruption of target molecules for the orientation of LC leading to an amplified optical signal. The Hg(2+) ion, which possesses a unique property to bind specifically to two DNA thymine (T) bases, is used as a model heavy metal ion. In the presence of Hg(2+), the specific oligonucleotide probes form a conformational reorganization of the oligonucleotide probes from hairpin structure to duplex-like complexes. The duplex-like complexes are then bound on the triethoxysilylbutyraldehyde/N,N-dimethyl-N-octadecyl (3-aminopropyl) trimethoxysilyl chloride (TEA/DMOAP)-coated substrate modified with capture probes, which can greatly distort the orientational profile of LC, making the optical image of LC cell birefringent as a result. The optical signal of LC sensor has a visible change at the Hg(2+) concentration of low to 0.1 nM, showing good detection sensitivity. The cost-effective LC sensing method can translate the concentration signal of heavy metal ions in solution into the presence of DNA duplexes and is expected to be a sensitive detection platform for heavy metal ions and other small molecule monitors. PMID:23214408

  8. Using support vector machines to improve elemental ion identification in macromolecular crystal structures

    PubMed Central

    Morshed, Nader; Echols, Nathaniel; Adams, Paul D.

    2015-01-01

    In the process of macromolecular model building, crystallographers must examine electron density for isolated atoms and differentiate sites containing structured solvent molecules from those containing elemental ions. This task requires specific knowledge of metal-binding chemistry and scattering properties and is prone to error. A method has previously been described to identify ions based on manually chosen criteria for a number of elements. Here, the use of support vector machines (SVMs) to automatically classify isolated atoms as either solvent or one of various ions is described. Two data sets of protein crystal structures, one containing manually curated structures deposited with anomalous diffraction data and another with automatically filtered, high-resolution structures, were constructed. On the manually curated data set, an SVM classifier was able to distinguish calcium from manganese, zinc, iron and nickel, as well as all five of these ions from water molecules, with a high degree of accuracy. Additionally, SVMs trained on the automatically curated set of high-resolution structures were able to successfully classify most common elemental ions in an independent validation test set. This method is readily extensible to other elemental ions and can also be used in conjunction with previous methods based on a priori expectations of the chemical environment and X-ray scattering. PMID:25945580

  9. Structural, spectral, linear and nonlinear optical properties of new nonlinear optical L-histidinium trichloroacetate crystals.

    PubMed

    Raj, S Gokul; Kumar, G Ramesh; Raghavalu, Thenneti; Kumar, P; Mohan, R; Jayavel, R

    2006-12-01

    Single crystals of a new histidinium salt: L-histidinium trichloroacetate {abbreviated as LHTCA; [(C(3)N(2)H(4))CH(2)CH(NH(3))(CO(2))](+)CCl(3)COO(-)} were grown by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in a non-centrosymmetric space group P2(1) of monoclinic system with cell parameters a=5.4505(18) A, b=25.769(8) A, c=9.210(2) A and beta=99.98(2) degrees. The vibrational structure of the compound confirms the presence of various functional groups in the molecule. The UV-vis-NIR spectrum shows a good transparency in the whole of the region from ultraviolet to near IR. The Kurtz powder SHG measurement confirms the frequency doubling of the crystal. Thermal behaviour of the crystals has been investigated by DSC analysis. These preliminary results suggest that LHTCA crystal can act as a potential and promising candidate for frequency doubling applications even from the near UV region to the near IR. PMID:16716647

  10. Formation of GPS-Linked Global Ensemble of Hydrogen Masers, and Comparison to JPL's Linear Ion Trap

    NASA Technical Reports Server (NTRS)

    Young, L. E.; Jefferson, D. C.; Lichten, S. M.; Tjoelker, R. L.; Maleki, L.

    1996-01-01

    This paper will describe the use of precision GPS time transfer to form an ensemble of hydrogen maser clocks. The performance of this ensemble, including the GPS time-transfer system, was measured relative to a stable Linear Ion Trap Standard.

  11. Crystallization of ion clouds in octupole traps: Structural transitions, core melting, and scaling laws

    SciTech Connect

    Calvo, F.; Champenois, C.; Yurtsever, E.

    2009-12-15

    The stable structures and melting properties of ion clouds in isotropic octupole traps are investigated using a combination of semianalytical and numerical models, with a particular emphasis at finite-size scaling effects. Small-size clouds are found to be hollow and arranged in shells corresponding approximately to the solutions of the Thomson problem. The shell structure is lost in clusters containing more than a few thousands of ions, the inner parts of the cloud becoming soft and amorphous. While melting is triggered in the core shells, the melting temperature follows the rule expected for three-dimensional dense particles, with a depression scaling linearly with the inverse radius.

  12. Degradation study of enniatins by liquid chromatography-triple quadrupole linear ion trap mass spectrometry.

    PubMed

    Serrano, A B; Meca, G; Font, G; Ferrer, E

    2013-12-15

    Enniatins A, A1, B and B1 (ENs) are mycotoxins produced by Fusarium spp. and are normal contaminants of cereals and derivate products. In this study, the stability of ENs was evaluated during food processing by simulation of pasta cooking. Thermal treatments at different incubation times (5, 10 and 15 min) and different pH (4, 7 and 10) were applied in an aqueous system and pasta resembling system (PRS). The concentrations of the targeted mycotoxins were determined using liquid chromatography coupled to tandem mass spectrometry. High percentages of ENs reduction (81-100%) were evidenced in the PRS after the treatments at 5, 10 and 15 min of incubation. In contrast to the PRS, an important reduction of the ENs was obtained in the aqueous system after 15 min of incubation (82-100%). In general, no significant differences were observed between acid, neutral and basic solutions. Finally, several ENs degradation products were identified using the technique of liquid chromatography-triple quadrupole linear ion trap mass spectrometry. PMID:23993608

  13. Theoretical modeling of the linear and nonlinear optical properties of organic crystals within the rigorous local field theory (RLFT)

    SciTech Connect

    Seidler, T.; Stadnicka, K.; Champagne, B.

    2015-03-30

    This contribution summarizes our current findings in the field of calculating and predicting the linear and second-order nonlinear electric susceptibility tensor components of organic crystals. The methodology used for this purpose is based on a combination of the electrostatic interaction scheme developed by Munn and his coworkers (RLFT) with high-level electronic structure calculations. We compare the results of calculations with available experimental data for several examples of molecular crystals. We show the quality of the final results is influenced by i) the chromophore geometry, ii) the method used for molecular properties calculations and iii) the partitioning scheme used. In conclusion we summarize further plans to improve the reliability and predictability of the method.

  14. Linear energy transfer effects on time profiles of scintillation of Ce-doped LiCaAlF6 crystals

    NASA Astrophysics Data System (ADS)

    Yanagida, Takayuki; Koshimizu, Masanori; Kurashima, Satoshi; Iwamatsu, Kazuhiro; Kimura, Atsushi; Taguchi, Mitsumasa; Fujimoto, Yutaka; Asai, Keisuke

    2015-12-01

    We measured temporal profiles of the scintillation of Ce-doped LiCaAlF6 scintillator crystals at different linear energy transfers (LETs). Based on the comparison of high-LET temporal profiles with those at low LET, a fast component was observed only at low LET. The disappearance of the fast component at high LET is tentatively ascribed to the quenching of excited states at crystal defects owing to the interaction between excited states via the Auger process. In addition, the rise and the initial decay behavior were dependent on the LET. This LET-dependent behavior is explained by an acceleration process and a deceleration process in energy transfer at high LET. The LET-dependent temporal profiles provide the basis for a discrimination technique of gamma-ray and neutron detection events using these scintillators based on the nuclear reaction, 6Li(n,α)t.

  15. X-Ray Rocking Curve and Ferromagnetic Resonance Investigations of Ion-Implanted Crystals

    NASA Astrophysics Data System (ADS)

    Speriosu, Virgil Simon

    A kinematical model for general Bragg case x-ray diffraction in nonuniform films is presented. The model incorporates depth-dependent strain and structure factor. Profiles of strain and structure factor are obtained by fitting experimental rocking curves. The method is applicable to ion-implanted, diffused and multilayer crystalline structures such as heterojunctions. A comparison is made between profiles of strain and incoherent atomic displacements obtained from rocking curves and Rutherford backscattering spectrometry in Ne('+) -implanted Gd(,3)Ga(,5)O(,12). The ranges of sensitivity of the two techniques overlap for about one decade in implantation dose up to the amorphous threshold. The two techniques are in excellent agreement on the near-surface strain, but differ significantly at depths below (TURNEQ)500A. The profiles of incoherently displaced atoms agree within a factor of two. The rocking curve method is combined with analysis of ferromagnetic resonance spectra for characterization of Gd,Tm,Ga:YIG films implanted with Ne('+), He('+), and H(,2)('+) over a wide range of doses. Profiles of normal strain, lateral strain and damage were obtained. Magnetic profiles were compared with the strain profiles. The local change in uniaxial anisotropy field (DELTA)H(,k) with increasing strain shows an initially linear rise for both He('+) and Ne('+), in agreement with the magnetostriction effect. For strain values greater than (TURNEQ)1.5%, (DELTA)H(,k) saturates and decreases to nearly zero when the material becomes paramagnetic. For H(,2)('+) implantation the total (DELTA)H(,k) consists of a magnetostrictive contribution due to strain and of a comparable excess contribution associated with the local concentration of hydrogen. With increasing annealing temperature the excess (DELTA)H(,k) diminishes and above 400(DEGREES)C the only component of (DELTA)H(,k) is magnetostrictive. For all three species the behavior of the saturation magnetization 4(pi)M, the exchange

  16. Structural Distinction of Diacyl-, Alkylacyl, and Alk-1-Enylacyl Glycerophosphocholines as [M - 15]- Ions by Multiple-Stage Linear Ion-Trap Mass Spectrometry with Electrospray Ionization

    NASA Astrophysics Data System (ADS)

    Hsu, Fong-Fu; Lodhi, Irfan J.; Turk, John; Semenkovich, Clay F.

    2014-08-01

    We describe a linear ion-trap (LIT) multiple-stage (MSn) mass spectrometric approach towards differentiation of alkylacyl, alk-1-enylacyl- and diacyl-glycerophoscholines (PCs) as the [M - 15]- ions desorbed by electrospray ionization (ESI) in the negative-ion mode. The MS4 mass spectra of the [M - 15 - R2'CH = CO]- ions originated from the three PC subfamilies are readily distinguishable, resulting in unambiguous distinction of the lipid classes. This method is applied to two alkyl ether rich PC mixtures isolated from murine bone marrow neutrophils and kidney, respectively, to explore its utility in the characterization of complex PC mixture of biological origin, resulting in the realization of the detailed structures of the PC species, including various classes and many minor isobaric isomers.

  17. Effect of swift heavy ion beam irradiation on the dielectric and ferroelectric properties of pure and cobalt doped TGS crystals

    NASA Astrophysics Data System (ADS)

    Bajpai, P. K.; Shah, Deepak; Kumar, Ravi

    2012-01-01

    Effect of swift heavy ion (100 MeV O 7+ ion) beam irradiation on the temperature and frequency dependence of real ( ɛ') and imaginary ( ɛ″) parts of dielectric permittivity in pure and Co 2+ doped TGS crystals are analyzed. Irradiation with swift heavy ion beam changes the dielectric response considerably. Observed dielectric peak in irradiated crystals shifts towards lower temperature and broadens up; the reduction in peak value, shift in temperature and broadening changes systematically with fluence. The most interesting results of SHI irradiation are (i) the dielectric loss peak value ( emax″) in all crystals is invariably less in comparison to the value in unirradiated crystals (ii) the minimum value of dielectric loss peak ( emax″) occurs at different fluence in different crystals, and (iii) a second loss peak is observed below Tc in CTGS10 especially at higher fluence. It seems that irradiation creates/strengthens internal field in the crystals by orienting the domains through some mechanism that is not clear at present. The observed results could be explained if one presumes that irradiation annihilate the defects already present in the crystals by creating local charges and thermal gradient resulting into internal bias field. Ferroelectric hysteresis loops demonstrate the internal bias field developing in the SHI irradiated crystals. It is argued that SHI irradiation is a better alternate in comparison to cobalt doping in inhibiting dipolar switching in TGS crystal.

  18. Orientating layers with adjustable pretilt angles for liquid crystals deposited by a linear atmospheric pressure plasma source

    SciTech Connect

    Jian, Shih-Jie; Kou, Chwung-Shan; Hwang, Jennchang; Lee, Chein-Dhau; Lin, Wei-Cheng

    2013-06-15

    A method for controlling the pretilt angles of liquid crystals (LC) was developed. Hexamethyldisiloxane polymer films were first deposited on indium tin oxide coated glass plates using a linear atmospheric pressure plasma source. The films were subsequently treated with the rubbing method for LC alignment. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements were used to characterize the film composition, which could be varied to control the surface energy by adjusting the monomer feed rate and input power. The results of LC alignment experiments showed that the pretilt angle continuously increased from 0 Degree-Sign to 90 Degree-Sign with decreasing film surface energy.

  19. Non-polar InGaN quantum dot emission with crystal-axis oriented linear polarization

    SciTech Connect

    Reid, Benjamin P. L. Chan, Christopher C. S.; Taylor, Robert A.; Kocher, Claudius; Zhu, Tongtong; Oehler, Fabrice; Oliver, Rachel A.

    2015-04-27

    Polarization sensitive photoluminescence is performed on single non-polar InGaN quantum dots. The studied InGaN quantum dots are found to have linearly polarized emission with a common polarization direction defined by the [0001] crystal axis. Around half of ∼40 studied dots have a polarization degree of 1. For those lines with a polarization degree less than 1, we can resolve fine structure splittings between −800 μeV and +800 μeV, with no clear correlation between fine structure splitting and emission energy.

  20. Ultrafast state detection and 2D ion crystals in a Paul trap

    NASA Astrophysics Data System (ADS)

    Ip, Michael; Ransford, Anthony; Campbell, Wesley

    2016-05-01

    Projective readout of quantum information stored in atomic qubits typically uses state-dependent CW laser-induced fluorescence. This method requires an often sophisticated imaging system to spatially filter out the background CW laser light. We present an alternative approach that instead uses simple pulse sequences from a mode-locked laser to affect the same state-dependent excitations in less than 1 ns. The resulting atomic fluorescence occurs in the dark, allowing the placement of non-imaging detectors right next to the atom to improve the qubit state detection efficiency and speed. We also study 2D Coulomb crystals of atomic ions in an oblate Paul trap. We find that crystals with hundreds of ions can be held in the trap, potentially offering an alternative to the use of Penning traps for the quantum simulation of 2D lattice spin models. We discuss the classical physics of these crystals and the metastable states that are supported in 2D. This work is supported by the US Army Research Office.

  1. Nonlinear optical spectroscopy of Ce sup 3+ ions in insulating crystals

    SciTech Connect

    Piehler, D.

    1990-11-01

    The experiments described are: electronic coherent anti-stokes Raman spectroscopy. CARS is a form of four-waving mixing in which two input lasers at frequencies {omega}{sub 1} and {omega}{sub 2} interact within a nonlinear medium to produce a third coherent beam at frequency {omega}{sub 3} = 2{omega}{sub 1} {minus} {omega}{sub 2}. Resonances are observed in the signal at {omega}{sub 3} as ({omega}{sub 1} {minus} {omega}{sub 2}) is swept through the electronic energy levels of the Ce{sup 3+} ion. 4f {yields} 5d two-photon absorption. The simplest and most direct way to investigate the nature of the 5d configuration in Ce{sup 3+}:LuPO{sub 4} is by two-photon absorption. Although two-photon transients between the 4f and 5d configurations are formally parity forbidden they are allowed in second order by the odd parity components of the crystal field. Simulated electronic Raman scattering. One of the original motivations for this work was to determine if electronic Raman processes in rare earth crystals could be strong enough for the observation of stimulated electronic Raman scattering. Stimulated electronic Raman scattering has been observed in atomic vapors, but not never involving ions in crystals. No stimulated electronic Raman processes were observed in CeF{sub 3}. 117 refs., 45 figs., 7 tabs.

  2. Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method

    SciTech Connect

    Saravanan, R.; Rajesh, D.; Rajasekaran, S. V.; Perumal, R.; Chitra, M.; Jayavel, R.

    2013-02-05

    Single crystals of sodium potassium niobate (K{sub 0.5}Na{sub 0.5})NbO{sub 3} (KNN) were grown by flux method and crystals were irradiated with 45 MeV Li ions to modify the electrical properties. Energy of the irradiated heavy ion was lower than the threshold energy to produce columnar defect and only clusters of defect was observed. The surface morphology of the irradiated single crystals was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). The results show that the surface roughness value was found to increase with increasing fluence.

  3. Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method

    NASA Astrophysics Data System (ADS)

    Saravanan, R.; Rajesh, D.; Rajasekaran, S. V.; Perumal, R.; Chitra, M.; Jayavel, R.

    2013-02-01

    Single crystals of sodium potassium niobate (K0.5Na0.5)NbO3 (KNN) were grown by flux method and crystals were irradiated with 45 MeV Li ions to modify the electrical properties. Energy of the irradiated heavy ion was lower than the threshold energy to produce columnar defect and only clusters of defect was observed. The surface morphology of the irradiated single crystals was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). The results show that the surface roughness value was found to increase with increasing fluence.

  4. Homogeneous alignment of nematic liquid crystals by ion beam etched surfaces

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.; Mahmood, R.; Johnson, D. L.

    1979-01-01

    A wide range of ion beam etch parameters capable of producing uniform homogeneous alignment of nematic liquid crystals on SiO2 films are discussed. The alignment surfaces were generated by obliquely incident (angles of 5 to 25 deg) argon ions with energies in the range of 0.5 to 2.0 KeV, ion current densities of 0.1 to 0.6 mA sq cm and etch times of 1 to 9 min. A smaller range of ion beam parameters (2.0 KeV, 0.2 mA sq cm, 5 to 10 deg and 1 to 5 min.) were also investigated with ZrO2 films and found suitable for homogeneous alignment. Extinction ratios were very high (1000), twist angles were small ( or = 3 deg) and tilt-bias angles very small ( or = 1 deg). Preliminary scanning electron microscopy results indicate a parallel oriented surface structure on the ion beam etched surfaces which may determine alignment.

  5. Broad-Spectrum Drug Screening Using Liquid Chromatography-Hybrid Triple-Quadrupole Linear Ion Trap Mass Spectrometry.

    PubMed

    Stone, Judy

    2016-01-01

    Urine is processed with a simple C18 solid-phase extraction (SPE) and reconstituted in mobile phase. The liquid chromatography system (LC) injects 10 μL of extracted sample onto a reverse-phase LC column for gradient analysis with ammonium formate/acetonitrile mobile phases. Drugs in the column eluent become charged in the ion source using positive electrospray ionization (ESI). Pseudomolecular ions (M + H) are analyzed by a hybrid triple-quadrupole linear ion trap (QqQ and QqLIT) mass spectrometer using an SRM-IDA-EPI acquisition. An initial 125 compound selected ion monitoring (SRM) survey scan (triple quadrupole or QqQ mode) is processed by the information-dependent acquisition (IDA) algorithm. The IDA algorithm selects SRM signals from the survey scan with a peak height above the threshold (the three most abundant SRM signals above 1000 cps) to define precursor ions for subsequent dependent scanning. In the dependent QqLIT scan(s), selected precursor ion(s) are passed through the first quadrupole (Q1), fragmented with three different collision energies in the collision cell (Q2 or q), and product ions are collected in the third quadrupole (Q3), now operating as a linear ion trap (LIT). The ions are scanned out of the LIT in a mass dependent manner to produce a full-scan product ion spectrum (m/z 50-700) defined as an Enhanced (meaning acquired in LIT mode) Product Ion (EPI) spectrum (Mueller et al., Rapid Commun Mass Spectrom 19:1332-1338, 2005). Each EPI spectrum is linked to its precursor ion and to the associated SRM peak from the survey scan. EPI spectra are automatically searched against a 125 drug library of reference EPI spectra for identification. When the duty cycle is complete (one survey scan of 125 SRMs plus 0-3 dependent IDA-EPI scans) the mass spectrometer begins another survey scan of the 125 SRMs. PMID:26660183

  6. Molecular dynamics study of linear and comb-like polyelectrolytes in aqueous solution: effect of Ca2+ ions

    NASA Astrophysics Data System (ADS)

    Tong, Kefeng; Song, Xingfu; Sun, Shuying; Xu, Yanxia; Yu, Jianguo

    2014-08-01

    All-atom molecular dynamics simulations were employed to provide microscopic mechanism for the salt tolerance of polyelectrolytes dispersants. The conformational variation of polyelectrolytes and interactions between COO- groups and counterions/water molecules were also studied via radius of gyration and pair correlations functions. Sodium polyacrylate (NaPA) and sodium salts of poly(acrylic acid)-poly(ethylene oxide) (NaPA-PEO) were selected as the representative linear and comb-like polyelectrolyte, respectively. The results show that Ca2+ ions interact with COO- groups much stronger than Na+ ions and can bring ion-bridging interaction between intermolecular COO- groups in the NaPA systems. While in the NaPA-PEO systems, the introduced PEO side chains can prevent backbone chains from ion-bridging interactions and weaken the conformational changes. The present results can help in selecting and designing new-type efficient polyelectrolyte dispersants with good salt tolerance.

  7. Charge states of medium energy He ions scattered from single and poly-crystal surfaces

    NASA Astrophysics Data System (ADS)

    Okazawa, T.; Shibuya, K.; Nishimura, T.; Kido, Y.

    2007-03-01

    High-resolution medium energy ion scattering (MEIS) spectroscopy has unveiled fine structures of surfaces and interfaces. However, problematic issues arise due to its excellent energy resolution. In particular, when one uses He+ beams, the He+ fraction η+ (1) for the scattering component from top-layer atoms is frequently non-equilibrated owing to short exit path length. This leads to significant uncertainties of the absolute amount of atoms located on top of a surface. To overcome this difficulty, it is essential to acquire reliable data of equilibrium and non-equilibrium charge fractions and also to model the charge exchange process based on a simple picture. In this paper, we analyze the MEIS spectra from single and poly crystals of Si, Ni and Cu together with c-axis oriented graphite and derive electron capture (σ10) and loss (σ01) cross sections dependent on emerging ion velocity. Here, we assume that a He ion when arrives at a Maffin-tin sphere after a large angle collision takes the He+ state and then undergoes many charge exchanging collisions with valence electrons until leaving an electronic surface. The velocity dependent σ10 and σ01 values derived well reproduce equilibrium and non-equilibrium charge fractions of He+ except for graphite and poly-crystal Si at relatively large emerging angles. Such a deviation comes from the markedly anisotropic distributions of the valence electrons of Si and graphite with strong covalent bonds.

  8. Optimized ion acceleration using high repetition rate, variable thickness liquid crystal targets

    NASA Astrophysics Data System (ADS)

    Poole, Patrick; Willis, Christopher; Cochran, Ginevra; Andereck, C. David; Schumacher, Douglass

    2015-11-01

    Laser-based ion acceleration is a widely studied plasma physics topic for its applications to secondary radiation sources, advanced imaging, and cancer therapy. Recent work has centered on investigating new acceleration mechanisms that promise improved ion energy and spectrum. While the physics of these mechanisms is not yet fully understood, it has been observed to dominate for certain ranges of target thickness, where the optimum thickness depends on laser conditions including energy, pulse width, and contrast. The study of these phenomena is uniquely facilitated by the use of variable-thickness liquid crystal films, first introduced in P. L. Poole et al. PoP21, 063109 (2014). Control of the formation parameters of these freely suspended films such as volume, temperature, and draw speed allows on-demand thickness variability between 10 nanometers and several 10s of microns, fully encompassing the currently studied thickness regimes with a single target material. The low vapor pressure of liquid crystal enables in-situ film formation and unlimited vacuum use of these targets. Details on the selection and optimization of ion acceleration mechanism with target thickness will be presented, including recent experiments on the Scarlet laser facility and others. This work was performed with support from the DARPA PULSE program through a grant from AMRDEC and by the NNSA under contract DE-NA0001976.

  9. Determination of vanillin, ethyl vanillin, and coumarin in infant formula by liquid chromatography-quadrupole linear ion trap mass spectrometry.

    PubMed

    Shen, Yan; Han, Chao; Liu, Bin; Lin, Zhengfeng; Zhou, Xiujin; Wang, Chengjun; Zhu, Zhenou

    2014-02-01

    A simple, precise, accurate, and validated liquid chromatography-quadrupole linear ion trap mass spectrometry method was developed for the determination of vanillin, ethyl vanillin, and coumarin in infant formula samples. Following ultrasonic extraction with methanol/water (1:1, vol/vol), and clean-up on an HLB solid-phase extraction cartridge (Waters Corp., Milford, MA), samples were separated on a Waters XSelect HSS T3 column (150 × 2.1-mm i.d., 5-μm film thickness; Waters Corp.), with 0.1% formic acid solution-acetonitrile as mobile phase at a flow rate of 0.25 mL/min. Quantification of the target was performed by the internal standard approach, using isotopically labeled compounds for each chemical group, to correct matrix effects. Data acquisition was carried out in multiple reaction monitoring transitions mode, monitoring 2 multiple reaction monitoring transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the enhanced product ion modus of the linear ion trap. The novel liquid chromatography-quadrupole linear ion trap mass spectrometry platform offers the best sensitivity and specificity for characterization and quantitative determination of vanillin, ethyl vanillin, and coumarin in infant formula and fulfills the quality criteria for routine laboratory application. PMID:24359823

  10. Visible to near-infrared supercontinuum generation in yttrium orthosilicate bulk crystal and ion implanted planar waveguide.

    PubMed

    Xiang, Bingxi; Ren, Xikui; Ruan, Shuangchen; Wang, Lei; Yan, Peiguang; Han, Huangpu; Wang, Meng; Yin, Jinde

    2016-01-01

    This paper reports on the supercontinuum generation in yttrium orthosilicate bulk crystal and 6-mm-long ion implanted planar waveguide. The waveguide is fabricated by 6 MeV oxygen ions implantation with fluence of 5 × 10(14) ions/cm(2) at room temperature. The yttrium orthosilicate bulk crystal and waveguide are pumped using a mode-locked Ti:Sapphire laser with a center wavelength of 800 nm. The generated broadest supercontinuum spans 720 nm (at -30 dB points) from 380 to 1100 nm in bulk crystal and 510 nm (at -30 dB points) from 490 to 1000 nm in ion implanted waveguide, respectively. Compared to the bulk crystal, the ion implanted waveguide requires almost three orders of magnitude lower pump power to achieve a similar level of broadening. The supercontinuum is generated in the normal dispersion regime and exhibits a relatively smooth spectral shape. Our research findings indicate that ion implantation is an efficient method to produce waveguide in yttrium orthosilicate crystal for low-threshold supercontinuum generation. PMID:27527662

  11. Visible to near-infrared supercontinuum generation in yttrium orthosilicate bulk crystal and ion implanted planar waveguide

    PubMed Central

    Xiang, Bingxi; Ren, Xikui; Ruan, Shuangchen; Wang, Lei; Yan, Peiguang; Han, Huangpu; Wang, Meng; Yin, Jinde

    2016-01-01

    This paper reports on the supercontinuum generation in yttrium orthosilicate bulk crystal and 6-mm-long ion implanted planar waveguide. The waveguide is fabricated by 6 MeV oxygen ions implantation with fluence of 5 × 1014 ions/cm2 at room temperature. The yttrium orthosilicate bulk crystal and waveguide are pumped using a mode-locked Ti:Sapphire laser with a center wavelength of 800 nm. The generated broadest supercontinuum spans 720 nm (at −30 dB points) from 380 to 1100 nm in bulk crystal and 510 nm (at −30 dB points) from 490 to 1000 nm in ion implanted waveguide, respectively. Compared to the bulk crystal, the ion implanted waveguide requires almost three orders of magnitude lower pump power to achieve a similar level of broadening. The supercontinuum is generated in the normal dispersion regime and exhibits a relatively smooth spectral shape. Our research findings indicate that ion implantation is an efficient method to produce waveguide in yttrium orthosilicate crystal for low-threshold supercontinuum generation. PMID:27527662

  12. Non-linear line-narrowing spectroscopy in mixed organic crystals

    NASA Astrophysics Data System (ADS)

    Riebe, Michael T.; Wright, John C.

    1987-08-01

    We report the elimination of inhomogeneous broadening in mixed organic crystals with multiply resonant four-wave mixing methods. Line narrowing and the line shifts characteristic of site selective methods are observed for both coherent anti-Stokes Raman spectroscopy (CARS) and multiply enhanced non-parametric spectrosocopy (MENS). The site selective capability of CARS is in agreement with the model proposed by Ouellette and Denariez-Roberge.

  13. Crystal structures of supramolecular assemblies based on a para-dicyclohexanocucurbit[6]uil with metal ions

    NASA Astrophysics Data System (ADS)

    Qin, Xiao; Chen, Wen-Jian; Zhang, Yun-Qian; Zhu, Qian-Jiang; Xue, Sai-Feng; Tao, Zhu

    2011-06-01

    Five crystals based on para-dicyclohexanocucurbit[6]uil (DCyHQ[6]) were synthesized and structurally characterized by single-crystal X-ray diffractions. They are {Dioxane@DCyHQ[6]}·18H 2O ( 1), {[Cu(HO)6]2DCyHQ[6]}·2SO42-·10HO ( 2), {[Zn(HO)6]2DCyHQ[6]}·2SO42-·10HO ( 3), {[Sr(HO)5]2DCyHQ[6]}·5Cl·(HO)+·8HO ( 4), {[Na(HO)4]2DCyHQ[6]}·4Br·2(HO)+·14HO ( 5). The compound 1 which is a dioxane @DCyHQ[6] inclusion host-guest complex; the other three crystal structures of the compounds 2, 3 and 4 show supramolecular assemblies comprising of DCyHQ[6] and metal ions or their aqueous complexes through hydrogen bonding; while the crystal structure of the compound 5 shows a one-dimensional supramolecular polymer through direct coordination of sodium cations to the portal carbonyl oxygen atoms of the DCyHQ[6].

  14. Research on temperature field of KDP crystal under ion beam cleaning.

    PubMed

    Li, Furen; Xie, Xuhui; Tie, Guipeng; Hu, Hao; Zhou, Lin

    2016-06-20

    KH2PO4 (KDP) crystal is a kind of excellent nonlinear optical component used as a laser frequency conversion unit in a high-power laser system. However, KDP crystal has raised a huge challenge in regards to its fabrication for high precision: KDP crystal has special physical and chemical characteristics. Abrasive-free water-dissolution magnetorheological finishing is used in KDP figuring in our lab. But the iron powders of MRF fluid are easily embedded into the soft surface of KDP crystal, which will greatly decrease the laser-induced damage resistance. This paper proposes to utilize ion beam figuring (IBF) technology to figure and clean the surface of a KDP component. Although IBF has many good performances, the thermal effect control is a headachy problem for the KDP process. To solve this problem, we have established its thermal effect models, which are used to calculate a component's surface temperature and thermal gradient in the whole process. By this way, we can understand how to control a temperature map and its gradient in the IBF process. Many experiments have been done to validate and optimize this method. Finally, a KDP component with the size of 200×200×12  mm is successfully processed by this method. PMID:27409114

  15. A compensated multi-pole linear ion trap mercury frequency standard for ultra-stable timekeeping.

    PubMed

    Burt, Eric A; Diener, William A; Tjoelker, Robert L

    2008-12-01

    The multi-pole linear ion trap frequency standard (LITS) being developed at the Jet Propulsion Laboratory (JPL) has demonstrated excellent short- and long-term stability. The technology has now demonstrated long-term field operation providing a new capability for timekeeping standards. Recently implemented enhancements have resulted in a record line Q of 5 x 10(12) for a room temperature microwave atomic transition and a short-term fractional frequency stability of 5 x 10(-14)/tau(1/2). A scheme for compensating the second order Doppler shift has led to a reduction of the combined sensitivity to the primary LITS systematic effects below 5 x 10(-17) fractional frequency. Initial comparisons to JPL's cesium fountain clock show a systematic floor of less than 2 x 10(-16). The compensated multi-pole LITS at JPL was operated continuously and unattended for a 9-mo period from October 2006 to July 2007. During that time it was used as the frequency reference for the JPL geodetic receiver known as JPLT, enabling comparisons to any clock used as a reference for an International GNSS Service (IGS) site. Comparisons with the laser-cooled primary frequency standards that reported to the Bureau International des Poids et Mesures (BIPM) over this period show a frequency deviation less than 2.7 x 10(-17)/day. In the capacity of a stand-alone ultra-stable flywheel, such a standard could be invaluable for long-term timekeeping applications in metrology labs while its methodology and robustness make it ideal for space applications as well. PMID:19126484

  16. Development of a Linear Ion Trap Mass Spectrometer (LITMS) Investigation for Future Planetary Surface Missions

    NASA Technical Reports Server (NTRS)

    Brinckerhoff, W.; Danell, R.; Van Ameron, F.; Pinnick, V.; Li, X.; Arevalo, R.; Glavin, D.; Getty, S.; Mahaffy, P.; Chu, P.; Zacny, K.; Rogacki, S.; Grubisic, A.; Cornish, T.

    2014-01-01

    Future surface missions to Mars and other planetary bodies will benefit from continued advances in miniature sensor and sample handling technologies that enable high-performance chemical analyses of natural samples. Fine-scale (approx.1 mm and below) analyses of rock surfaces and interiors, such as exposed on a drill core, will permit (1) the detection of habitability markers including complex organics in association with their original depositional environment, and (2) the characterization of successive layers and gradients that can reveal the time-evolution of those environments. In particular, if broad-based and highly-sensitive mass spectrometry techniques could be brought to such scales, the resulting planetary science capability would be truly powerful. The Linear Ion Trap Mass Spectrometer (LITMS) investigation is designed to conduct fine-scale organic and inorganic analyses of short (approx.5-10 cm) rock cores such as could be acquired by a planetary lander or rover arm-based drill. LITMS combines both pyrolysis/gas chromatograph mass spectrometry (GCMS) of sub-sampled core fines, and laser desorption mass spectrometry (LDMS) of the intact core surface, using a common mass analyzer, enhanced from the design used in the Mars Organic Molecule Analyzer (MOMA) instrument on the 2018 ExoMars rover. LITMS additionally features developments based on the Sample Analysis at Mars (SAM) investigation on MSL and recent NASA-funded prototype efforts in laser mass spectrometry, pyrolysis, and precision subsampling. LITMS brings these combined capabilities to achieve its four measurement objectives: (1) Organics: Broad Survey Detect organic molecules over a wide range of molecular weight, volatility, electronegativity, concentration, and host mineralogy. (2) Organic: Molecular Structure Characterize internal molecular structure to identify individual compounds, and reveal functionalization and processing. (3) Inorganic Host Environment Assess the local chemical

  17. Linear ion-trap mass spectrometric characterization of human pituitary nitrotyrosine-containing proteins

    NASA Astrophysics Data System (ADS)

    Zhan, Xianquan; Desiderio, Dominic M.

    2007-01-01

    The nitric oxide-mediated Tyr-nitration of endogenous proteins is associated with several pathological and physiological processes. In order to investigate the presence - and potential roles - of Tyr-nitration in the human pituitary, a large-format two-dimensional gel separation plus a Western blot against a specific anti-3-nitrotyrosine antibody were used to separate and detect nitroproteins from a human pituitary proteome. The nitroproteins were subjected to in-gel trypsin digestion, and high-sensitivity vacuum matrix-assisted laser desorption/ionization (vMALDI) linear ion-trap tandem mass spectrometry was used to analyze the tryptic peptides. Those MS/MS data were used to determine the amino acid sequence and the specific nitration site of each tryptic nitropeptide, and were matched to corresponding proteins with Bioworks TuboSEQUEST software. Compared to our previous study, 16 new nitrotyrosine-immunoreactive positive Western blot spots were found within the area pI 3.0-10 and Mr 10-100 kDa. Four new nitroproteins were discovered: the stanniocalcin 1 precursor--involved in calcium and phosphate metabolism; mitochondrial co-chaperone protein HscB, which might act as a co-chaperone in iron-sulfur cluster assembly in mitochrondria; progestin and adipoQ receptor family member III--a seven-transmembrane receptor; proteasome subunit alpha type 2--involved in an ATP/ubiquitin-dependent non-lysosomal proteolytic pathway. Those data demonstrate that nitric oxide-mediated Tyr-nitration might participate in various biochemical, metabolic, and pathological processes in the human pituitary.

  18. Liquid Crystal Alignment on Solution Derived Zinc Oxide Films via Ion Beam Irradiation.

    PubMed

    Park, Hong-Gyu; Han, Jae-Jun; Seo, Dae-Shik

    2016-03-01

    A 75-nm-thick ZnO film was deposited by a sol-gel method on indium-tin oxide (ITO)-coated glass. This film served as a liquid crystal (LC) alignment layer. We report the fabrication and characteristics of this film after ion-beam (IB) irradiation. Uniform LC alignment was achieved at an IB incident energy above 2400 eV. The IB-treated ZnO surface was analyzed by X-ray photoelectron spectroscopy (XPS), monitoring the intensity of the Zn 2p and O 1s peaks as a function of IB-irradiation energy density. The electro-optical (EO) characteristics of a twisted nematic-liquid crystal display (TN-LCD) were comparable to rubbed polyimide. PMID:27455726

  19. Titanium dioxide surface modification via ion-beam bombardment for vertical alignment of nematic liquid crystal.

    PubMed

    Na, Hyun-Jae; Lee, Jin-Woo; Lee, Won-Kyu; Lim, Ji-Hun; Park, Hong-Gyu; Kim, Byoung-Yong; Hwang, Jeong-Yeon; Han, Jeong-Min; Seo, Dae-Shik

    2010-04-15

    We introduce the characteristics of the titanium dioxide (TiO(2)) inorganic film deposited by rf magnetron sputtering for liquid crystal display applications. The TiO(2) films demonstrated vertical alignment (VA) of the liquid crystals (LCs) obtained by using ion-beam (IB) bombardment. As observed by using x-ray photoelectron spectroscopy, the chemical structure of the TiO(2) was changed by IB bombardment, altering the Ti-O bonding of the Ti 2p spectra to lower intensity levels. Breaking Ti-O bonding by IB bombardment created pretilt angles between the TiO(2) film and LC molecules. The better voltage-transmittance characteristics of the VA LCDs based on TiO(2) film were measured and compared with the same characteristics of polyimide film. PMID:20410949

  20. Polarization bremsstrahlung of a hydrogen-like ion in a single crystal

    SciTech Connect

    Astapenko, V. A.

    2009-01-15

    Polarization bremsstrahlung (PB) that arises when a fast hydrogen-like ion is scattered in a single crystal is investigated theoretically. Four types of the process are analyzed that are caused by virtual excitation of electrons of the target and of the incident particle (IP), as well as by a coherent and incoherent interaction between the IP and the single crystal. The spectral, angular, and velocity (of the IP) characteristics of PB are calculated with regard to the spectral function of a photodetector. Optimal observation conditions and regions in which different types of PB are dominant are determined, and the dependence of these regions on the charge of the IP nucleus and of the target atoms is revealed.

  1. Crystal structure induced residue formation on 4H-SiC by reactive ion etching

    NASA Astrophysics Data System (ADS)

    Liu, Yi-hong; Sun, Yu-jun; Zhao, Gao-jie; Liao, Li-ming; Wang, Tao; Chen, Zhi-zhan

    2016-06-01

    The (000 1 ¯) C face of 4H-SiC wafer was etched by reactive ion etching in SF6/O2 plasma. The effect of etching parameters, such as work pressure, SF6:O2 ratio and etching time, on the residue formation were systematically investigated. The residue morphologies were observed by scanning electron microscopy and atomic force microscopy, respectively. The residues have spike shape and their facets are defined as { 1 1 ¯ 0 2 ¯ } crystal planes. They are formed at beginning of the etching and no new spikes are generated as prolonging etching time. Both work pressure and SF6:O2 ratio play significant role in the spike formation. The residues can be eliminated completely by increasing the SF6:O2 ratio and work pressure. On the basis of experimental results and of 4H-SiC crystal structure, the spike formation model is proposed.

  2. Improving the intensity and efficiency of compressed echo in rare-earth-ion-doped crystal

    NASA Astrophysics Data System (ADS)

    Xiu-Rong, Ma; Yu-Qing, Liang; Song, Wang; Shuang-Gen, Zhang; Yun-Long, Shan

    2016-07-01

    We investigate the intensity and efficiency of a compressed echo, which is important in arbitrary waveform generation (AWG). A new model of compressed echo is proposed based on the optical Bloch equations, which exposes much more detailed parameters than the conventional model, such as the time delay of the chirp lasers, the nature of the rare-earth-ion-doped crystal, etc. According to the novel model of compressed echo, we find that reducing the time delay of the chirp lasers and scanning the lasers around the center frequency of the inhomogeneously broadened spectrum, while utilizing a crystal with larger coherence time and excitation lifetime can improve the compressed echo’s intensity and efficiency. The theoretical analysis is validated by numerical simulations. Project supported by Special Funds for Scientific and Technological Innovation Projects in Tianjin, China (Grant No. 10FDZDGX00400) and the Tianjin Research Program of Application Foundation and Advanced Technology, China (Grant No. 15JCQNJC01100).

  3. The direct crystallographic evidences of undissociated HCl hydrates and unconventional cis-linear conformation of the water dimer in an organic crystal determined at ambient condition

    NASA Astrophysics Data System (ADS)

    Zhang, Cong; Feng, Ya; Shen, Chen; Yong, Guoping

    2016-08-01

    The unprecedentedly undissociated HCl hydrates, and unconventional cis-linear conformation of the water dimer at ambient condition were found in a novel organic crystal by direct crystallographic evidences. The peculiar tricyclo[6.2.0.0]-type configuration of hydrogen-bonding network induces such unexpected undissociated HCl hydrates, and unusual cis-linear conformation of the water dimer.

  4. Linear optical properties and electronic structures of poly(3-hexylthiophene) and poly(3-hexylselenophene) crystals from first principles

    NASA Astrophysics Data System (ADS)

    Tsumuraya, Takao; Song, Jung-Hwan; Freeman, Arthur J.

    2012-08-01

    Linear optical properties of regio-regular-poly(3-hexythiophene) (rr-P3HT) and regio-regular-poly(3-hexyselenophene) (rr-P3HS) are investigated in relation to their anisotropic crystal structure by means of first-principles density functional calculations. The optical spectra are evaluated by calculating its dielectric functions, focusing on the frequency dependence of the imaginary part. The optical transition along the π conjugation-connecting backbone direction is found to be the most significant at the band edges. A group-theoretical analysis of the matrix elements is given to explain the interband transitions. The optical spectra, electronic structures, and structural stabilities are calculated using the all-electron full-potential linearized augmented plane wave (FLAPW) method within the local-density approximation. We proposed several possible crystal structures of rr-P3HT and performed structural optimizations to determine a stable structure. Comparing the total energy differences among these relaxed structures, a base-centered monoclinic structure belonging to the space group A2 is found to be the most stable structure. In the electronic structure, C and S orbitals belonging to polythiophene backbones are the biggest contributors at the valence band maximum and conduction band minimum, but there is almost no contribution from the hexyl side chains. Last, the differences in electronic and optical properties between rr-P3HT and rr-P3HS are discussed.

  5. Thermal-Independent Properties of PIN-PMN-PT Single-Crystal Linear-Array Ultrasonic Transducers

    PubMed Central

    Chen, Ruimin; Wu, Jinchuan; Lam, Kwok Ho; Yao, Liheng; Zhou, Qifa; Tian, Jian; Han, Pengdi; Shung, K. Kirk

    2013-01-01

    In this paper, low-frequency 32-element linear-array ultrasonic transducers were designed and fabricated using both ternary Pb(In1/2Nb1/2)–Pb(Mg1/3Nb2/3)–PbTiO3 (PIN-PMN-PT) and binary Pb(Mg1/3Nb2/3)–PbTiO3 (PMN-PT) single crystals. Performance of the array transducers was characterized as a function of temperature ranging from room temperature to 160°C. It was found that the array transducers fabricated using the PIN-PMN-PT single crystal were capable of satisfactory performance at 160°C, having a −6-dB bandwidth of 66% and an insertion loss of 37 dB. The results suggest that the potential of PIN-PMN-PT linear-array ultrasonic transducers for high-temperature ultrasonic transducer applications is promising. PMID:23221227

  6. Magnetism and variable temperature and pressure crystal structures of a linear oligonuclear cobalt bis-semiquinonate.

    PubMed

    Overgaard, Jacob; Møller, Louise H; Borup, Mette A; Tricoire, Maxime; Walsh, James P S; Diehl, Marcel; Rentschler, Eva

    2016-08-01

    The crystal structure of the first oligomeric cobalt dioxolene complex, Co3(3,5-DBSQ)2((t)BuCOO)4(NEt3)2, 1, where DBSQ is 3,5-di-tert-butyl-semiquinonate, has been studied at various temperatures between 20 and 200 K. Despite cobalt-dioxolene complexes being generally known for their extensive ability to exhibit valence tautomerism (VT), we show here that the molecular geometry of compound 1 is essentially unchanged over the full temperature range, indicating the complete absence of electron transfer between ligand and metal. Magnetic susceptibility measurements clearly support the lack of VT between 8 and 300 K. The crystal structure is also determined at elevated pressures in the range from 0 to 2.5 GPa. The response of the crystal structure is surprisingly dependent on the dynamics of pressurisation: following rapid pressurization to 2 GPa, a structural phase transition occurs; yet, this is absent when the pressure is increased incrementally to 2.6 GPa. In the new high pressure phase, Z' is 2 and one of the two molecules displays changes in the coordination of one bridging carboxylate from μ2:κO:κO' to μ2:κ(2)O,O':κO', while the other molecule remains unchanged. Despite the significant changes to the molecular connectivity, analysis of the crystal structures shows that the phase transition leaves the spin and oxidation states of the molecules unaltered. Intermolecular interactions in the high pressure crystal structures have been analysed using Hirshfeld surfaces but they cannot explain the origin of the phase transition. The lack of VT in this first oligomeric Co-dioxolene complex is speculated to be due to the coordination geometry of the terminal Co-atoms, which are trigonal bipyramidally coordinated, different from the more common octahedral coordination. The energy that is gained by a hs-to-ls change in Oh is equal to Δ, while in the case of the trigonal bipyramidal (C3v), the energy gain is equal to the splitting between d(z(2)) and degenerate d

  7. Selective liquid crystal molecule orientation on ion beam irradiated tantalum oxide ultrathin films

    SciTech Connect

    Lim, Ji-Hun; Oh, Byeong-Yun; Lee, Won-Kyu; Lee, Kang-Min; Na, Hyun-Jae; Kim, Byoung-Yong; Seo, Dae-Shik; Han, Jeong-Min; Hwang, Jeong-Yeon

    2009-09-21

    We recently achieved the homogeneous alignment of liquid crystal (LC) on amorphous Ta{sub 2}O{sub 5} layers. This study demonstrates that LC layers could be aligned either homogeneously or vertically by increasing the growth temperature of rf magnetron sputtering device and the irradiation time of the DuoPIGatron type Ar ion beam device causing uniform and dense plasma. We attained two LC orientations by observing Ta 4f and O 1s peak shifts with x-ray photoelectron spectroscopy. Moreover, the decreased thickness of layers with high-k dielectric constants helped to decrease driving LC voltages and in turn to achieve low power consumption.

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

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

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

  9. Emittance study of a 28 GHz electron cyclotron resonance ion source for the Rare Isotope Science Project superconducting linear accelerator.

    PubMed

    Park, Bum-Sik; Hong, In-Seok; Jang, Ji-Ho; Jin, Hyunchang; Choi, Sukjin; Kim, Yonghwan

    2016-02-01

    A 28 GHz electron cyclotron resonance (ECR) ion source is being developed for use as an injector for the superconducting linear accelerator of the Rare Isotope Science Project. Beam extraction from the ECR ion source has been simulated using the KOBRA3-INP software. The simulation software can calculate charged particle trajectories in three dimensional complex magnetic field structures, which in this case are formed by the arrangement of five superconducting magnets. In this study, the beam emittance is simulated to understand the effects of plasma potential, mass-to-charge ratio, and spatial distribution. The results of these simulations and their comparison to experimental results are presented in this paper. PMID:26931953

  10. Emittance study of a 28 GHz electron cyclotron resonance ion source for the Rare Isotope Science Project superconducting linear accelerator

    NASA Astrophysics Data System (ADS)

    Park, Bum-Sik; Hong, In-Seok; Jang, Ji-Ho; Jin, Hyunchang; Choi, Sukjin; Kim, Yonghwan

    2016-02-01

    A 28 GHz electron cyclotron resonance (ECR) ion source is being developed for use as an injector for the superconducting linear accelerator of the Rare Isotope Science Project. Beam extraction from the ECR ion source has been simulated using the KOBRA3-INP software. The simulation software can calculate charged particle trajectories in three dimensional complex magnetic field structures, which in this case are formed by the arrangement of five superconducting magnets. In this study, the beam emittance is simulated to understand the effects of plasma potential, mass-to-charge ratio, and spatial distribution. The results of these simulations and their comparison to experimental results are presented in this paper.

  11. Site-selective spectroscopy of garnet crystals doped with chromium ions.

    PubMed

    Örücü, Hümeyra; Özen, Gönül; Di Bartolo, Baldassare; Collins, John

    2012-09-01

    Site-selective spectroscopy is a tool that can be used to uncover the presence of multiple sites available to optically active ions in host lattices. In this Article, we present techniques that can be applied to appraise the different sites that may occur in systems where charge compensation is required or in systems where such compensation is not present. We then consider some garnet crystals doped with chromium ions. For the Cr-doped garnets (YAG, GGG, GSGG, and CYMGG), we present luminescence and lifetime data over a wide temperature range, and infer not only the presence of different centers, but also the interaction among them as a function of temperature. PMID:22867053

  12. Surface reformation and electro-optical characteristics of liquid crystal alignment layers using ion beam irradiation

    SciTech Connect

    Oh, Byeong-Yun; Lee, Kang-Min; Kim, Byoung-Yong; Kim, Young-Hwan; Han, Jin-Woo; Han, Jeong-Min; Lee, Sang-Keuk; Seo, Dae-Shik

    2008-09-15

    The surface modification characteristics of liquid crystal (LC) alignment layers irradiated with various argon (Ar) ion beam (IB) energies were investigated as a substitute for rubbing technology. Various pretilt angles were created on the IB-irradiated polyimide (PI) surfaces after IB irradiation, but the Ar ions did not alter the morphology on the PI surface, indicating that the pretilt angle was not due to microgrooves. The chemical bonding states of the IB-irradiated PI surfaces were analyzed in detail by x-ray photoelectron spectroscopy to verify the compositional behavior for the LC alignment. Chemical structure analysis showed that the alignment ability of LCs was due to the preferential reorientation of the carbon network due to the breaking of C=O double bonds in the imide ring parallel to the incident IB direction. The potential of applying nonrubbing technology to display devices was further supported by the superior electro-optical characteristics compared to rubbed PI.

  13. Influence of crystal orientation on hardness and nanoindentation deformation in ion-irradiated stainless steels

    NASA Astrophysics Data System (ADS)

    Miura, Terumitsu; Fujii, Katsuhiko; Fukuya, Koji; Takashima, Keisuke

    2011-10-01

    The influence of crystal orientation on hardness and the range of plastic deformation caused by nanoindentation was investigated in a solution annealed type 316 stainless steel irradiated with Fe 2+ ions. The hardness was a function of grain orientation and was correlated with the Taylor factor averaged over three normal directions of the contact surface of the Berkovich indenter. The transmission electron microscope observations of the deformation microstructure under the indentations showed that the range of plastic deformation reached up to 10 times the indent depth for unirradiated material and depended on the orientation relation between the contact surface of the indenter and the slip directions. The range of plastic deformation decreased as the damage structure developed in ion irradiation.

  14. Homeotropic orientation behavior of nematic liquid crystals induced by copper ions.

    PubMed

    Li, Guang; Gao, Bin; Yang, Meng; Chen, Long-Cong; Xiong, Xing-Liang

    2015-06-01

    A homeotropic ordering film of nematic liquid crystal (LC) induced by copper ions (Cu(2+)) had been developed. The Cu(ClO4)2 was directly spin-coated on the glass substrate without any other chemical modification. A homeotropic orientation of LC thin-film was generated by the interfacial chemical interaction between nitrile-containing LC and copper ions on the surface. Results showed that an appropriate density of Cu(2+) could shorten the response time of orientation, but a shelf-time was prolonged. The LC film fabrication not only offered a simple process, but also presented a great repeatability to detect organophosphonates (DMMP). This study provided guidance for the design of LC films responding to organic molecules as a biosensor. PMID:25935262

  15. Spectroscopy and Thermometry of Drumhead Modes in a Mesoscopic Trapped-Ion Crystal using Entanglement

    NASA Astrophysics Data System (ADS)

    Sawyer, Brian; Britton, Joseph; Keith, Adam; Wang, Joseph; Freericks, James; Uys, Hermann; Biercuk, Michael; Bollinger, John

    2012-06-01

    Studies of quantum mechanics at intermediate scales between microscopic and mesoscopic regimes have recently focused on the observation of quantum coherent phenomena in optomechanical systems. We demonstrate spectroscopy and thermometry of individual motional modes in a mesoscopic 2D ion array using entanglement-induced decoherence as a method of transduction. Our system is a ˜400 μm-diameter planar crystal of several hundred ^9Be^+ ions exhibiting complex drumhead modes in the confining potential of a Penning trap. Exploiting precise control over the ^9Be^+ valence electron spins, we apply a homogeneous spin-dependent optical dipole force to excite arbitrary transverse modes with an effective wavelength approaching the interparticle spacing (˜20 μm). Center-of-mass displacements of ˜120 pm are detected via entanglement of spin and motional degrees of freedom.

  16. Spectroscopy and thermometry of drumhead modes in a mesoscopic trapped-ion crystal using entanglement.

    PubMed

    Sawyer, Brian C; Britton, Joseph W; Keith, Adam C; Wang, C-C Joseph; Freericks, James K; Uys, Hermann; Biercuk, Michael J; Bollinger, John J

    2012-05-25

    We demonstrate spectroscopy and thermometry of individual motional modes in a mesoscopic 2D ion array using entanglement-induced decoherence as a method of transduction. Our system is a ~400 μm-diameter planar crystal of several hundred 9Be(+) ions exhibiting complex drumhead modes in the confining potential of a Penning trap. Exploiting precise control over the 9Be(+) valence electron spins, we apply a homogeneous spin-dependent optical dipole force to excite arbitrary transverse modes with an effective wavelength approaching the interparticle spacing (~20 μm). Center-of-mass displacements below 1 nm are detected via the entanglement of spin and motional degrees of freedom. PMID:23003249

  17. Spectroscopy and Thermometry of Drumhead Modes in a Mesoscopic Trapped-Ion Crystal Using Entanglement

    NASA Astrophysics Data System (ADS)

    Sawyer, Brian C.; Britton, Joseph W.; Keith, Adam C.; Wang, C.-C. Joseph; Freericks, James K.; Uys, Hermann; Biercuk, Michael J.; Bollinger, John J.

    2012-05-01

    We demonstrate spectroscopy and thermometry of individual motional modes in a mesoscopic 2D ion array using entanglement-induced decoherence as a method of transduction. Our system is a ˜400μm-diameter planar crystal of several hundred Be+9 ions exhibiting complex drumhead modes in the confining potential of a Penning trap. Exploiting precise control over the Be+9 valence electron spins, we apply a homogeneous spin-dependent optical dipole force to excite arbitrary transverse modes with an effective wavelength approaching the interparticle spacing (˜20μm). Center-of-mass displacements below 1 nm are detected via the entanglement of spin and motional degrees of freedom.

  18. Collision cross section calculations for polyatomic ions considering rotating diatomic/linear gas molecules

    SciTech Connect

    Larriba-Andaluz, Carlos Hogan, Christopher J.

    2014-11-21

    Structural characterization of ions in the gas phase is facilitated by measurement of ion collision cross sections (CCS) using techniques such as ion mobility spectrometry. Further information is gained from CCS measurement when comparison is made between measurements and accurately predicted CCSs for model ion structures and the gas in which measurements are made. While diatomic gases, namely molecular nitrogen and air, are being used in CCS measurement with increasingly prevalency, the majority of studies in which measurements are compared to predictions use models in which gas molecules are spherical or non-rotating, which is not necessarily appropriate for diatomic gases. Here, we adapt a momentum transfer based CCS calculation approach to consider rotating, diatomic gas molecule collisions with polyatomic ions, and compare CCS predictions with a diatomic gas molecule to those made with a spherical gas molecular for model spherical ions, tetra-alkylammonium ions, and multiply charged polyethylene glycol ions. CCS calculations are performed using both specular-elastic and diffuse-inelastic collisions rules, which mimic negligible internal energy exchange and complete thermal accommodation, respectively, between gas molecule and ion. The influence of the long range ion-induced dipole potential on calculations is also examined with both gas molecule models. In large part we find that CCSs calculated with specular-elastic collision rules decrease, while they increase with diffuse-inelastic collision rules when using diatomic gas molecules. Results clearly show the structural model of both the ion and gas molecule, the potential energy field between ion and gas molecule, and finally the modeled degree of kinetic energy exchange between ion and gas molecule internal energy are coupled to one another in CCS calculations, and must be considered carefully to obtain results which agree with measurements.

  19. Collision cross section calculations for polyatomic ions considering rotating diatomic/linear gas molecules.

    PubMed

    Larriba-Andaluz, Carlos; Hogan, Christopher J

    2014-11-21

    Structural characterization of ions in the gas phase is facilitated by measurement of ion collision cross sections (CCS) using techniques such as ion mobility spectrometry. Further information is gained from CCS measurement when comparison is made between measurements and accurately predicted CCSs for model ion structures and the gas in which measurements are made. While diatomic gases, namely molecular nitrogen and air, are being used in CCS measurement with increasingly prevalency, the majority of studies in which measurements are compared to predictions use models in which gas molecules are spherical or non-rotating, which is not necessarily appropriate for diatomic gases. Here, we adapt a momentum transfer based CCS calculation approach to consider rotating, diatomic gas molecule collisions with polyatomic ions, and compare CCS predictions with a diatomic gas molecule to those made with a spherical gas molecular for model spherical ions, tetra-alkylammonium ions, and multiply charged polyethylene glycol ions. CCS calculations are performed using both specular-elastic and diffuse-inelastic collisions rules, which mimic negligible internal energy exchange and complete thermal accommodation, respectively, between gas molecule and ion. The influence of the long range ion-induced dipole potential on calculations is also examined with both gas molecule models. In large part we find that CCSs calculated with specular-elastic collision rules decrease, while they increase with diffuse-inelastic collision rules when using diatomic gas molecules. Results clearly show the structural model of both the ion and gas molecule, the potential energy field between ion and gas molecule, and finally the modeled degree of kinetic energy exchange between ion and gas molecule internal energy are coupled to one another in CCS calculations, and must be considered carefully to obtain results which agree with measurements. PMID:25416874

  20. Lattice defects and recombination processes in non-linear crystals LiB3O5

    NASA Astrophysics Data System (ADS)

    Ogorodnikov, I. N.; Kruzhalov, A. V.; Porotnikov, A. V.; Yakovlev, Yu. V.

    The paper presents the results of a study of kinetics of the recombination processes in crystals LiB3O5 (LBO) obtained by the use of time-resolved luminescence and optical absorption spectroscopy. It was revealed that the observed peculiarities of the recombination processes in LBO are due to a participation of the trapped electron (B2+) and hole (O-) centres. In the framework of a model of the competing trapped hole centres the time dependence of both transient optical absorption and luminescence as well as their temperature dependencies was interpreted.

  1. Phenomenological description of ion-beam-induced epitaxial crystallization of amorphous silicon

    SciTech Connect

    Priolo, F. ); Spinella, C. ); Rimini, E. )

    1990-03-15

    In this paper we report detailed experimental measurements on the dependence of the ion-beam-induced epitaxial crystallization (IBIEC) of amorphous silicon on dopant concentration. The results show that the presence of B, P, and As dopants enhances IBIEC. In particular a logarithmic relationship between the ion-induced growth rate and dopant concentration is found for all of the impurities. In order to explain this behavior a phenomenological model of IBIEC will also be presented. The model postulates that the same defect is responsible for both thermal and ion-beam annealing. It combines the structural and electronic features of the description proposed by Williams and Elliman for conventional thermal epitaxial growth, with the intracascade approach of Jackson to the ion-assisted regrowth. Defects responsible for IBIEC are identified in kinklike steps formed onto (110) ledges at the crystalline-amorphous interface. These kinks are assumed to be generated thermally within the thermal-spike regime of each collision cascade. After defect generation, then, our approach follows Jackson's as far as the temporal evolution of defects is concerned. The model can account for all of the experimental results previously explained by the Jackson model and, moreover, can account for the doping and orientation dependences of IBIEC. This description is discussed and quantitatively compared with the experimental data.

  2. Cation disordering in magnesium aluminate spinel crystals induced by electron or ion irradiation

    NASA Astrophysics Data System (ADS)

    Soeda, Takeshi; Matsumura, Syo; Kinoshita, Chiken; Zaluzec, Nestor J.

    2000-12-01

    Structural changes in magnesium aluminate spinel (MgO · nAl 2O 3) single crystals, which were irradiated with 900 keV electrons or 1 MeV Ne + ions at 873 K, were examined by electron channeling enhanced X-ray microanalysis. Unirradiated MgO · Al 2O 3 has a tendency to form the normal spinel configuration, where Mg 2+ ions and Al 3+ ions occupy mainly the tetrahedral and the octahedral sites, respectively. Electron irradiation induces simple cation disordering between the tetrahedral sites and the octahedral sites in MgO · Al 2O 3. In addition to cation disordering, slight evacuation of cations from the tetrahedral sites to the octahedral sites occurs in a peak-damaged area in MgO · Al 2O 3 irradiated with Ne + ions. In contrast, cation disordering is suppressed in MgO · 2.4Al 2O 3 irradiated with electrons. The structural vacancies, present in the non-stoichiometric compound, appear to be effective in promoting irradiation damage recovery through interstitial-vacancy recombination.

  3. Effects of positron concentration, ion temperature, and plasma {beta} value on linear and nonlinear two-dimensional magnetosonic waves in electron-positron-ion plasmas

    SciTech Connect

    Mushtaq, A.; Shah, H.A.

    2005-01-01

    Magnetosonic waves are intensively studied due to their importance in space plasmas and also in fusion plasmas where they are used in particle acceleration and heating experiments. This work considers magnetosonic waves propagating obliquely at an angle {theta} to an external magnetic field in an electron-positron-ion plasma, using the effective one-fluid magnetohydrodynamic model. Two separate modes (fast and slow) for the waves are discussed in the linear approximation, and the Kadomstev-Petviashvilli soliton equation is derived by using reductive perturbation scheme for these modes in the nonlinear regime. It is observed that for both the modes the angle {theta}, positron concentration, ion temperature, and plasma {beta}-value affect the propagation properties of solitary waves and behave differently from the simple electron-ion plasmas. Likewise, current density, electric field, and magnetic field for these waves are investigated, for their dependence on the above mentioned parameters.

  4. Controlled synthesis of linear and cyclic liquid crystals containing conformationally flexible structural units

    NASA Astrophysics Data System (ADS)

    Asandei, Alexandru Dragos

    This thesis decribes the design, synthesis and characterization of a large variety of molecular, macromolecular and supramolecular liquid crystalline (LC) systems with linear, cyclic, and combinations of linear and cyclic architectures. These structures are based on mesogens that display conformational isomerism. Several series of macrocyclics based on 1-(4-hydroxyphenyl)-2-(2-methyl-4-hydroxyphenyl)ethane (MBPE) and various alpha,omega-dibromoalkanes were synthesized and characterized. These macrocyclics display more stable and broader LC phases than the corresponding linear polymers. Relatively minor modifications in the structure of the mesogen, spacer or microstructure of polymeric chains have a strong effect on the phase behavior of main chain polyethers. This is demonstrated for polymers based on 1-(4-hydroxyphenyl)-2-(4-hydroxy-4'-biphenylyl)butane (TPB') and alpha,omega-dibromoalkanes containing from 4 to 19 methylenic units. A stepwise synthetic procedure is described for the synthesis of a series of LC macrocyclics based of TPB' and 1,10-dibromodecane. Large increases in the yields by comparison with the one-pot method are obtained, and the procedure is also illustrated by the synthesis of the first example of a liquid crystalline bicyclic compound. The stepwise synthesis and characterization of macrocyclic monomers and of the first examples of side chain and main chain LC polymers containing supramolecular mesogens based on collapsed macrocyclics building blocks are described and discussed. An iterative stepwise procedure that allows for an exponential 2spn growth in molecular weight after n synthetic cycles is presented and applied to the synthesis of linear polyethers based on 1-(4-hydroxy-4'-biphenylyl)-2-(4-hydroxyphenyl)butane (TPB) and 1,10-dibromodecane. A library of linear monodisperse oligomers and polymers with a degree of polymerization (DP) up to 33 and with a variety of chain ends was generated, and the dependence of the phase behavior of

  5. Non-linear photoelectron effect contributes to the formation of negative matrix ions in UV-MALDI.

    PubMed

    Alonso, E; Zenobi, R

    2016-07-20

    The mechanism of negative ion formation in matrix-assisted laser desorption/ionization (MALDI) is less well understood than that of positive ions: electron capture, disproportionation, and liberation of negatively charged sample molecules or clusters have been proposed to produce the initial anions in MALDI. Here, we propose that the non-linear photoelectric effect can explain the emission of electrons from the metallic target material. Moreover, electrons with sufficient kinetic energy (0-10 eV) could be responsible for the formation of initial negative ions. Gas-phase electron capture by neutral 2,5-dihydroxy benzoic acid (DHB) to yield M(-) is investigated on the basis of a coupled physical and chemical dynamics (CPCD) theory from the literature. A three-layer energy mass balance model is utilized to calculate the surface temperature of the matrix, which is used to determine the translational temperature, the number of desorbed matrix molecules per unit area, and the ion velocity. Calculations of dissociative attachment and autoionization rates of DHB are presented. It was found that both processes contribute significantly to the formation of [M - H](-) and [M - H2](-), although the predicted yield in the fluence range of 5-100 mJ cm(-2) is low, certainly less than that for positive ions M(+). This work represents the first proposal for a comprehensive theoretical description of negative ion formation in UV-MALDI. PMID:27181273

  6. Magnetic properties of Dy3+ ions and crystal field characterization in YF3:Dy3+ and DyF3 single crystals

    NASA Astrophysics Data System (ADS)

    Savinkov, A. V.; Korableva, S. L.; Rodionov, A. A.; Kurkin, I. N.; Malkin, B. Z.; Tagirov, M. S.; Suzuki, H.; Matsumoto, K.; Abe, S.

    2008-12-01

    The dc magnetic susceptibilities of the orthorhombic DyF3 single crystals have been measured in the temperature range between 1.8 and 300 K. The susceptibility along the b-axis does not depend on temperature below TC = 2.55 K and is equal to the demagnetizing factor of the sample, that gives evidence for the ferromagnetic phase induced by the magnetic dipole-dipole interactions between the Dy3+ ions. The saturation moment of 8.5 μB/Dy3+ along the b-axis was determined from magnetization measurements. The observed strong anisotropy of the magnetic susceptibility at low temperatures agrees with the measured anisotropic g-tensor of the ground state of impurity Dy3+ ions in YF3 single crystals. The results of measurements are interpreted in the frameworks of the crystal field theory and the mean magnetic field approximation.

  7. A linear relationship between crystal size and fragment binding time observed crystallographically: implications for fragment library screening using acoustic droplet ejection.

    PubMed

    Cole, Krystal; Roessler, Christian G; Mulé, Elizabeth A; Benson-Xu, Emma J; Mullen, Jeffrey D; Le, Benjamin A; Tieman, Alanna M; Birone, Claire; Brown, Maria; Hernandez, Jesus; Neff, Sherry; Williams, Daniel; Allaire, Marc; Orville, Allen M; Sweet, Robert M; Soares, Alexei S

    2014-01-01

    High throughput screening technologies such as acoustic droplet ejection (ADE) greatly increase the rate at which X-ray diffraction data can be acquired from crystals. One promising high throughput screening application of ADE is to rapidly combine protein crystals with fragment libraries. In this approach, each fragment soaks into a protein crystal either directly on data collection media or on a moving conveyor belt which then delivers the crystals to the X-ray beam. By simultaneously handling multiple crystals combined with fragment specimens, these techniques relax the automounter duty-cycle bottleneck that currently prevents optimal exploitation of third generation synchrotrons. Two factors limit the speed and scope of projects that are suitable for fragment screening using techniques such as ADE. Firstly, in applications where the high throughput screening apparatus is located inside the X-ray station (such as the conveyor belt system described above), the speed of data acquisition is limited by the time required for each fragment to soak into its protein crystal. Secondly, in applications where crystals are combined with fragments directly on data acquisition media (including both of the ADE methods described above), the maximum time that fragments have to soak into crystals is limited by evaporative dehydration of the protein crystals during the fragment soak. Here we demonstrate that both of these problems can be minimized by using small crystals, because the soak time required for a fragment hit to attain high occupancy depends approximately linearly on crystal size. PMID:24988328

  8. A Linear Relationship between Crystal Size and Fragment Binding Time Observed Crystallographically: Implications for Fragment Library Screening Using Acoustic Droplet Ejection

    PubMed Central

    Birone, Claire; Brown, Maria; Hernandez, Jesus; Neff, Sherry; Williams, Daniel; Allaire, Marc; Orville, Allen M.; Sweet, Robert M.; Soares, Alexei S.

    2014-01-01

    High throughput screening technologies such as acoustic droplet ejection (ADE) greatly increase the rate at which X-ray diffraction data can be acquired from crystals. One promising high throughput screening application of ADE is to rapidly combine protein crystals with fragment libraries. In this approach, each fragment soaks into a protein crystal either directly on data collection media or on a moving conveyor belt which then delivers the crystals to the X-ray beam. By simultaneously handling multiple crystals combined with fragment specimens, these techniques relax the automounter duty-cycle bottleneck that currently prevents optimal exploitation of third generation synchrotrons. Two factors limit the speed and scope of projects that are suitable for fragment screening using techniques such as ADE. Firstly, in applications where the high throughput screening apparatus is located inside the X-ray station (such as the conveyor belt system described above), the speed of data acquisition is limited by the time required for each fragment to soak into its protein crystal. Secondly, in applications where crystals are combined with fragments directly on data acquisition media (including both of the ADE methods described above), the maximum time that fragments have to soak into crystals is limited by evaporative dehydration of the protein crystals during the fragment soak. Here we demonstrate that both of these problems can be minimized by using small crystals, because the soak time required for a fragment hit to attain high occupancy depends approximately linearly on crystal size. PMID:24988328

  9. On the effect of a non-uniform longitudinal ion flow on the linear ITG mode stability.

    NASA Astrophysics Data System (ADS)

    Lontano, Maurizio; Lazzaro, Enzo; Varischetti, Maria Cecilia

    2006-10-01

    A one-dimensional model for slab ion temperature gradient (ITG) modes, in the presence of an inhomogeneous equilibrium plasma velocity along the main magnetic field direction, has been formulated in the frame of a two-fluid guiding-center approximation. The physical effects of a magnetic field gradient and of the line curvature are included by means of a gravitational drift velocity. The magnetic shear across the plasma slab is also taken into account. The linear stability of slow plasma dynamics, under the assumptions of quasi-neutrality and adiabatic electrons, is described by means of a third-degree dispersion relation. Generally speaking, the presence of a sheared longitudinal ion velocity leads to the linear destabilization of the ITG modes, especially for flat equilibrium density profiles. Transverse quasi-linear fluxes of ion thermal energy and longitudinal momentum are calculated for different equilibrium profiles of the density, temperature, momentum, and magnetic shear. Plasma configurations leading to zero transverse (or even negative) momentum fluxes are exploited and discussed in the light of their experimental implementation.

  10. Mechanical response of UO2 single crystals submitted to low-energy ion irradiation

    NASA Astrophysics Data System (ADS)

    Nguyen, Tien-Hien; Debelle, Aurélien; Boulle, Alexandre; Garrido, Frédérico; Thomé, Lionel; Demange, Valérie

    2015-12-01

    {111}- and {100}-oriented UO2 single crystals were irradiated with 500-keV Ce3+ ions in the 1014-9 × 1014 cm-2 fluence range. The irradiation-induced strain was monitored using high-resolution X-ray diffraction. A mechanical modelling dedicated to thin irradiated layers was applied to account for the reaction of the unirradiated part of the crystals. The elastic strain, which is confined along the surface normal of the samples, increases with ion fluence until it is dramatically relieved. This behaviour is observed for both orientations. While the measured elastic strain depends on the crystallographic direction, the strain due to irradiation defects only is found to be equal for both directions, with a maximum value of ∼0.5%. Strain relaxation takes place at the damage peak, but the in-plane lattice parameter of the irradiated layer remains unchanged and equal to that of the pristine material. Meanwhile, the strain at the damaged/pristine interface continues to increase.

  11. Investigation of focused ion beam induced damage in single crystal diamond tools

    NASA Astrophysics Data System (ADS)

    Tong, Zhen; Luo, Xichun

    2015-08-01

    In this work, transmission electron microscope (TEM) measurements and molecular dynamics (MD) simulations were carried out to characterise the focused ion beam (FIB) induced damage layer in a single crystal diamond tool under different FIB processing voltages. The results obtained from the experiments and the simulations are in good agreement. The results indicate that during FIB processing cutting tools made of natural single crystal diamond, the energetic Ga+ collision will create an impulse-dependent damage layer at the irradiated surface. For the tested beam voltages in a typical FIB system (from 8 kV to 30 kV), the thicknesses of the damaged layers formed on a diamond tool surface increased from 11.5 nm to 27.6 nm. The dynamic damage process of FIB irradiation and ion-solid interactions physics leading to processing defects in FIB milling were emulated by MD simulations. The research findings from this study provide the in-depth understanding of the wear of nanoscale multi-tip diamond tools considering the FIB irradiation induced doping and defects during the tool fabrication process.

  12. Kinematic dust viscosity effect on linear and nonlinear dust-acoustic waves in space dusty plasmas with nonthermal ions

    SciTech Connect

    El-Hanbaly, A. M.; Sallah, M.; El-Shewy, E. K.; Darweesh, H. F.

    2015-10-15

    Linear and nonlinear dust-acoustic (DA) waves are studied in a collisionless, unmagnetized and dissipative dusty plasma consisting of negatively charged dust grains, Boltzmann-distributed electrons, and nonthermal ions. The normal mode analysis is used to obtain a linear dispersion relation illustrating the dependence of the wave damping rate on the carrier wave number, the dust viscosity coefficient, the ratio of the ion temperature to the electron temperatures, and the nonthermal parameter. The plasma system is analyzed nonlinearly via the reductive perturbation method that gives the KdV-Burgers equation. Some interesting physical solutions are obtained to study the nonlinear waves. These solutions are related to soliton, a combination between a shock and a soliton, and monotonic and oscillatory shock waves. Their behaviors are illustrated and shown graphically. The characteristics of the DA solitary and shock waves are significantly modified by the presence of nonthermal (fast) ions, the ratio of the ion temperature to the electron temperature, and the dust kinematic viscosity. The topology of the phase portrait and the potential diagram of the KdV-Burgers equation is illustrated, whose advantage is the ability to predict different classes of traveling wave solutions according to different phase orbits. The energy of the soliton wave and the electric field are calculated. The results in this paper can be generalized to analyze the nature of plasma waves in both space and laboratory plasma systems.

  13. Kinematic dust viscosity effect on linear and nonlinear dust-acoustic waves in space dusty plasmas with nonthermal ions

    NASA Astrophysics Data System (ADS)

    El-Hanbaly, A. M.; Sallah, M.; El-Shewy, E. K.; Darweesh, H. F.

    2015-10-01

    Linear and nonlinear dust-acoustic (DA) waves are studied in a collisionless, unmagnetized and dissipative dusty plasma consisting of negatively charged dust grains, Boltzmann-distributed electrons, and nonthermal ions. The normal mode analysis is used to obtain a linear dispersion relation illustrating the dependence of the wave damping rate on the carrier wave number, the dust viscosity coefficient, the ratio of the ion temperature to the electron temperatures, and the nonthermal parameter. The plasma system is analyzed nonlinearly via the reductive perturbation method that gives the KdV-Burgers equation. Some interesting physical solutions are obtained to study the nonlinear waves. These solutions are related to soliton, a combination between a shock and a soliton, and monotonic and oscillatory shock waves. Their behaviors are illustrated and shown graphically. The characteristics of the DA solitary and shock waves are significantly modified by the presence of nonthermal (fast) ions, the ratio of the ion temperature to the electron temperature, and the dust kinematic viscosity. The topology of the phase portrait and the potential diagram of the KdV-Burgers equation is illustrated, whose advantage is the ability to predict different classes of traveling wave solutions according to different phase orbits. The energy of the soliton wave and the electric field are calculated. The results in this paper can be generalized to analyze the nature of plasma waves in both space and laboratory plasma systems.

  14. Supercharging with m-nitrobenzyl alcohol and propylene carbonate: forming highly charged ions with extended, near-linear conformations.

    PubMed

    Going, Catherine C; Williams, Evan R

    2015-04-01

    The effectiveness of the supercharging reagents m-nitrobenzyl alcohol (m-NBA) and propylene carbonate at producing highly charged protein ions in electrospray ionization is compared. Addition of 5% m-NBA or 15% propylene carbonate increases the average charge of three proteins by ∼21% or ∼23%, respectively, when these ions are formed from denaturing solutions (water/methanol/acetic acid). These results indicate that both reagents are nearly equally effective at supercharging when used at their optimum concentrations. A narrowing of the charge state distribution occurs with both reagents, although this effect is greater for propylene carbonate. Focusing the ion signal into fewer charge states has the advantage of improving sensitivity. The maximum charge state of ubiquitin formed with propylene carbonate is 21+, four charges higher than previously reported. Up to nearly 30% of all residues in a protein can be charged, and the collisional cross sections of the most highly charged ions of both ubiquitin and cytochrome c formed with these supercharging reagents were measured for the first time and found to be similar to those calculated for theoretical highly extended, linear or near-linear conformations. Under native supercharging conditions, m-NBA is significantly more effective at producing high charge states than propylene carbonate. PMID:25719488

  15. Effects of material non-linearity on the residual stresses in a dendritic silicon crystal ribbon

    NASA Technical Reports Server (NTRS)

    Ray, Sujit K.; Utku, Senol

    1990-01-01

    Thermal stresses developed in a dendritic silicon crystal ribbon have been shown to cause plastic deformation and residual stresses in the ribbon. This paper presents an implementation of a numerical model proposed for thermoelastoplastic behavior of a material. The model has been used to study the effects of plasticity of silicon on the residual stresses. The material properties required to implement this model are all assumed, and the response of the material to the variations in these assumed parameters of the constitutive law and in the finite element mesh is investigated. The steady state growth process is observed to be periodic with nonzero residual stresses. Numerical difficulties are also encountered in the computer solution process, resulting in sharp jumps and large oscillations in the stress responses.

  16. Linear-stability theory of thermocapillary convection in a model of float-zone crystal growth

    NASA Technical Reports Server (NTRS)

    Neitzel, G. P.; Chang, K.-T.; Jankowski, D. F.; Mittelmann, H. D.

    1992-01-01

    Linear-stability theory has been applied to a basic state of thermocapillary convection in a model half-zone to determine values of the Marangoni number above which instability is guaranteed. The basic state must be determined numerically since the half-zone is of finite, O(1) aspect ratio with two-dimensional flow and temperature fields. This, in turn, means that the governing equations for disturbance quantities will remain partial differential equations. The disturbance equations are treated by a staggered-grid discretization scheme. Results are presented for a variety of parameters of interest in the problem, including both terrestrial and microgravity cases.

  17. A study of vacuum arc ion velocities using a linear set of probes

    SciTech Connect

    Hohenbild, Stefan; Grubel, Christoph; Yushkov, Georgy Yu.; Oks, Efim M.; Anders, Andre

    2008-07-15

    The most likely velocity of ions moving away from vacuum arc cathode spots was measured using a set of probes along the path of plasma expansion. The goal was to determine how much, if any, change of the ion drift velocity occurs in the expanded plasma. The arc discharge current was perturbed to create plasma density markers whose travel is picked up by the set of probes. It was found that the perturbation with current oscillations did not result in consistent data because ion current maxima and minima are not only determined by the plasma production but by the transients of the arc pulse and by the asymmetry of the ion velocity distribution function. Perturbation with a short current spike was more conclusive. The ion velocity was measured to be slightly reduced with increasing distance from the cathode, which can be explained by collisions of ions with the background of neutrals. The ion velocity was increased when the arc current was increased, which correlated with enhanced arc voltage and power dissipation. The ion velocity could be enhanced when the plasma was produced in a non-uniform magnetic field.

  18. Excimer laser crystallization of amorphous silicon carbide produced by ion implantation

    NASA Astrophysics Data System (ADS)

    Hedler, A.; Urban, S.; Falk, F.; Hobert, H.; Wesch, W.

    2003-01-01

    4H-SiC was implanted with 100-250 keV Ge + and Xe + ions and doses of 1×10 14 to 1×10 16 cm -2 at room temperature in order to produce 40-200 nm thick amorphous surface layers. The samples were irradiated with 1-50,000 pulses of a KrF excimer laser (248 nm wavelength, 30 ns pulse duration) using fluences of 150-900 mJ/cm 2 to investigate the crystallization process as a function of the laser parameters. Crystallization as well as redistribution of the impurity atoms were analyzed by Rutherford backscattering spectrometry and infrared reflection measurements. Phase transitions occurring during the irradiation were studied by means of time-resolved reflectivity measurements. In order to explain the observed phase transitions numerical analysis was performed by solving the inhomogeneous heat flow equation using the parameters of the corresponding phases. In this work, we give a consistent description of the experimental results by the numerical simulations for the given laser setup. Depending on the amorphous layer thickness, melting, solidification, and crystallization of the amorphous phase can be effectively controlled by both the laser fluence and the number of laser pulses.

  19. Zinc oxide nanolevel surface transformation for liquid crystal orientation by ion bombardment

    SciTech Connect

    Oh, Byeong-Yun; Lee, Won-Kyu; Kim, Young-Hwan; Seo, Dae-Shik

    2009-03-01

    This paper introduces the characteristics of the zinc oxide (ZnO) inorganic film deposited by radio-frequency magnetron sputtering as an alternative alignment layer for liquid crystal display (LCD) applications. The crystalline structure related to the texture formation of ZnO (1013) was observed with a tilt angle of approximately 28.1 deg. to the ZnO (0001) plane, leading to a smooth surface and high-density structure. Ion beam (IB) bombardment at various incident angles was used to induce liquid crystal (LC) alignment and cause the measured pretilt angle on ZnO films to assume a triangular contour. The orientation order of liquid crystal molecules was due to the van der Waals force for the vertical alignment of LCs with selective breaking of O-Zn bonds by IB bombardment. The contact angle contour as a function of the IB incident angle resembled the behavior of the pretilt angle. The pretilt angle is controllable by adjusting the surface features on ZnO films with IB bombardment. The electro-optic characteristics of vertically aligned (VA)-LCD based on ZnO film were comparable to those of VA-LCD based on polyimide, showing good potential of ZnO film as a LC alignment layer.

  20. Silver migration and trapping in ion implanted ZnO single crystals

    NASA Astrophysics Data System (ADS)

    Azarov, Alexander; Vines, Lasse; Rauwel, Protima; Monakhov, Edouard; Svensson, Bengt G.

    2016-05-01

    Potentially, group-Ib elements (Cu, Ag, and Au) incorporated on Zn sites can be used for p-type doping of ZnO, and in the present paper, we use ion implantation to introduce Ag atoms in wurtzite ZnO single crystals. Monitoring the Li behavior, being a residual impurity in the crystals, as a tracer, we demonstrate that Zn interstitials assist the Ag diffusion and lead to Ag pile-up behind the implanted region after annealing above 800 °C. At even higher temperatures, a pronounced Ag loss from the sample surface occurs and concurrently the Ag atoms exhibit a trap-limited diffusion into the crystal bulk with an activation energy of ˜2.6 eV. The dominant traps are most likely Zn vacancies and substitutional Li atoms, yielding substitutional Ag atoms. In addition, formation of an anomalous multipeak Ag distribution in the implanted near-surface region after annealing can be attributed to local implantation-induced stoichiometry disturbances leading to trapping of the Ag atoms by O and Zn vacancies in the vicinity of the surface and in the end-of-range region, respectively.

  1. Surface degeneration of W crystal irradiated with low-energy hydrogen ions.

    PubMed

    Fan, Hongyu; You, Yuwei; Ni, Weiyuan; Yang, Qi; Liu, Lu; Benstetter, Günther; Liu, Dongping; Liu, Changsong

    2016-01-01

    The damage layer of a W (100) crystal irradiated with 120 eV hydrogen ions at a fluence of up to 1.5 × 10(25)/m(2) was investigated by scanning electron microscopy and conductive atomic force microscopy (CAFM). The periodic surface degeneration of the W crystal at a surface temperature of 373 K was formed at increasing hydrogen fluence. Observations by CCD camera and CAFM indicate the existence of ultrathin surface layers due to low-energy H irradiation. The W surface layer can contain a high density of nanometer-sized defects, resulting in the thermal instability of W atoms in the surface layer. Our findings suggest that the periodic surface degeneration of the W crystal can be ascribed to the lateral erosion of W surface layers falling off during the low-energy hydrogen irradiation. Our density functional theory calculations confirm the thermal instability of W atoms in the top layer, especially if H atoms are adsorbed on the surface. PMID:27020839

  2. Surface degeneration of W crystal irradiated with low-energy hydrogen ions

    PubMed Central

    Fan, Hongyu; You, Yuwei; Ni, Weiyuan; Yang, Qi; Liu, Lu; Benstetter, Günther; Liu, Dongping; Liu, Changsong

    2016-01-01

    The damage layer of a W (100) crystal irradiated with 120 eV hydrogen ions at a fluence of up to 1.5 × 1025/m2 was investigated by scanning electron microscopy and conductive atomic force microscopy (CAFM). The periodic surface degeneration of the W crystal at a surface temperature of 373 K was formed at increasing hydrogen fluence. Observations by CCD camera and CAFM indicate the existence of ultrathin surface layers due to low-energy H irradiation. The W surface layer can contain a high density of nanometer-sized defects, resulting in the thermal instability of W atoms in the surface layer. Our findings suggest that the periodic surface degeneration of the W crystal can be ascribed to the lateral erosion of W surface layers falling off during the low-energy hydrogen irradiation. Our density functional theory calculations confirm the thermal instability of W atoms in the top layer, especially if H atoms are adsorbed on the surface. PMID:27020839

  3. Synthesis of large FeSe superconductor crystals via ion release/introduction and property characterization

    NASA Astrophysics Data System (ADS)

    Dongna, Yuan; Yulong, Huang; Shunli, Ni; Huaxue, Zhou; Yiyuan, Mao; Wei, Hu; Jie, Yuan; Kui, Jin; Guangming, Zhang; Xiaoli, Dong; Fang, Zhou

    2016-07-01

    Large superconducting FeSe crystals of (001) orientation have been prepared via a hydrothermal ion release/introduction route for the first time. The hydrothermally derived FeSe crystals are up to 10 mm×5 mm×0.3 mm in dimension. The pure tetragonal FeSe phase has been confirmed by x-ray diffraction (XRD) and the composition determined by both inductively coupled plasma atomic emission spectroscopy (ICP-AES) and energy dispersive x-ray spectroscopy (EDX). The superconducting transition of the FeSe samples has been characterized by magnetic and transport measurements. The zero-temperature upper critical field H c2 is calculated to be 13.2–16.7 T from a two-band model. The normal-state cooperative paramagnetism is found to be predominated by strong spin frustrations below the characteristic temperature T sn, where the Ising spin nematicity has been discerned in the FeSe superconductor crystals as reported elsewhere. Project supported by the National Natural Science Foundation of China (Grant Nos. 11574370, 11274358, and 11190020), the National Basic Research Program of China (Grant No. 2013CB921700), and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07020100).

  4. Hematite natural crystals: non-linear initial susceptibility at low temperature

    NASA Astrophysics Data System (ADS)

    Guerrero Suarez, S.; Martín-Hernández, F.

    2016-04-01

    Several works have reported that hematite has non-linear initial susceptibility at room temperature, like pyrrhotite or titanomagnetite, but there is no explanation for the observed behaviours yet. This study sets out to determine which physical property (grain-size, foreign cations content, domain walls displacements) controls the initial susceptibility. The performed measurements include microprobe analysis to determine magnetic phases different to hematite; initial susceptibility (300 K); hysteresis loops, SIRM and backfield curves at 77 K and 300 K to calculate magnetic parameters and minor loops at 77 K, to analyze initial susceptiblity and magnetization behaviours below Morin transition. The magnetic moment study at low temperatura is completed with measurements of Zero Field Cooled- Field Cooled (ZFC-FC) and AC-susceptibility in a range from 5-300 K. The minor loops show that the non-linearity of initial susceptibility is closely related to Barkhausen jumps. Because of initial magnetic susceptibility is controlled by domain structure it is difficult to establish a mathematical model to separate magnetic subfabrics in hematite-bearing rocks.

  5. Haematite natural crystals: non-linear initial susceptibility at low temperature

    NASA Astrophysics Data System (ADS)

    Guerrero-Suarez, S.; Martín-Hernández, F.

    2016-06-01

    Several works have reported that haematite has non-linear initial susceptibility at room temperature, like pyrrhotite or titanomagnetite, but there is no explanation for the observed behaviours yet. This study sets out to determine which physical property (grain size, foreign cations content and domain walls displacements) controls the initial susceptibility. The performed measurements include microprobe analysis to determine magnetic phases different to haematite; initial susceptibility (300 K); hysteresis loops, SIRM and backfield curves at 77 and 300 K to calculate magnetic parameters and minor loops at 77 K, to analyse initial susceptibility and magnetization behaviours below Morin transition. The magnetic moment study at low temperature is completed with measurements of zero field cooled-field cooled and AC susceptibility in a range from 5 to 300 K. The minor loops show that the non-linearity of initial susceptibility is closely related to Barkhausen jumps. Because of initial magnetic susceptibility is controlled by domain structure it is difficult to establish a mathematical model to separate magnetic subfabrics in haematite-bearing rocks.

  6. Prediction and assignment of site occupation and energy levels for Pb 2+ ions in crystal hosts

    NASA Astrophysics Data System (ADS)

    Sun, Qiang; Wang, Jing; Shi, Jinsheng

    2010-05-01

    The environmental factor h e of the host was calculated quantitatively in Pb 2+-doped 23 compounds based on the dielectric theory of chemical bond for complex crystals. The relationship between the A band energy E A of Pb 2+ and the environmental factor h e was intensively studied. The results indicate that E A of Pb 2+ decreases linearly with increasing of h e. A linear model was proposed which allows us to correctly predict and assign the site occupations and the position of A band for Pb 2+-doped compounds if the crystal structure and the refraction index were known. Applied to SrGa 2O 4:Pb 2+, CaAl 2B 2O 7:Pb 2+ and SrAl 2B 2O 7:Pb 2+, the theoretical predictions are in very good agreement with the experimental data. In SrGa 2O 4:Pb 2+, the excitation spectrum of Pb 2+ from two different cation sites was identified: the higher energy band of A (265 nm) from the site of Sr2, and the lower ones (280 nm) from the site of Sr1.

  7. MULTI-SPACECRAFT OBSERVATIONS OF LINEAR MODES AND SIDEBAND WAVES IN ION-SCALE SOLAR WIND TURBULENCE

    SciTech Connect

    Perschke, Christopher; Motschmann, Uwe; Narita, Yasuhito; Glassmeier, Karl-Heinz

    2014-10-01

    In the scenario of weak turbulence, energy is believed to be cascaded from smaller to larger wave numbers and frequencies due to weak wave-wave interactions. Based on its perturbative treatment one may regard plasma turbulence as a superposition of linear modes (or normal modes) and sideband waves (or nonlinear modes). In this study, we use magnetic field and plasma measurements of nine solar wind events obtained by the Cluster spacecraft and make extensive use of a high-resolution wave vector analysis method, the Multi-point Signal Resonator technique, to find frequencies and wave vectors of discrete modes on ion kinetic scales in the plasma rest frame. The primarily unstructured wave observations in the frequency-wave number diagram are classified into three distinct linear modes (proton Bernstein modes, helium-alpha Bernstein modes, and kinetic Alfvén waves) and the sideband waves by comparing with the dispersion relations derived theoretically from linear Vlasov theory using observational values of the plasma parameter beta and the propagation angle from the mean magnetic field. About 60% of the observed discrete modes can be explained by the linear modes, primarily as the proton Bernstein and the kinetic Alfvén waves, within the frequency uncertainties, while the rest of the population (about 40%) cannot be classified as linear modes due to the large deviation from dispersion relations. We conclude that both the linear modes and sideband wave components are needed to construct the wave picture of solar wind turbulence on ion-kinetic scales.

  8. Theoretical investigations of the optical and EPR spectra for trivalent cerium and ytterbium ions in orthorhombic YF3 crystal

    NASA Astrophysics Data System (ADS)

    Liu, Hong-Gang; Zheng, Wen-Chen

    2016-09-01

    The optical spectra and electron paramagnetic resonance (EPR) parameters (g factors and hyperfine structure constants A) for trivalent cerium and ytterbium ions in YF3 crystal with orthorhombic structure are investigated together by the complete diagonalization (of energy matrix) method (CDM). The obtained results are in reasonable agreement with the experimental ones. More importantly, two magnetically nonequivalent centers in YF3 crystal observed in EPR experiments are confirmed and ascribed to their specific positions in a unit cell by our calculations based on superposition model (SPM) analysis. Such identification of local sites with different magnetic properties would help us to understand not only the EPR spectra and magnetic susceptibility of other lanthanide ions doped in crystals with the same structure as YF3 but also the energy transfer scheme between two lanthanide ions occupying such two sites. All results are discussed carefully.

  9. Structuring of material parameters in lithium niobate crystals with low-mass, high-energy ion radiation

    NASA Astrophysics Data System (ADS)

    Peithmann, K.; Eversheim, P.-D.; Goetze, J.; Haaks, M.; Hattermann, H.; Haubrich, S.; Hinterberger, F.; Jentjens, L.; Mader, W.; Raeth, N. L.; Schmid, H.; Zamani-Meymian, M.-R.; Maier, K.

    2011-10-01

    Ferroelectric lithium niobate crystals offer a great potential for applications in modern optics. To provide powerful optical components, tailoring of key material parameters, especially of the refractive index n and the ferroelectric domain landscape, is required. Irradiation of lithium niobate crystals with accelerated ions causes strong structured modifications in the material. The effects induced by low-mass, high-energy ions (such as 3He with 41 MeV, which are not implanted, but transmit through the entire crystal volume) are reviewed. Irradiation yields large changes of the refractive index Δn, improved domain engineering capability within the material along the ion track, and waveguiding structures. The periodic modification of Δn as well as the formation of periodically poled lithium niobate (PPLN) (supported by radiation damage) is described. Two-step knock-on displacement processes, 3He→Nb and 3He→O causing thermal spikes, are identified as origin for the material modifications.

  10. A photoluminescence study of CuInSe2 single crystals ion implanted with 5 keV hydrogen

    NASA Astrophysics Data System (ADS)

    Yakushev, M. V.; Krustok, J.; Grossberg, M.; Volkov, V. A.; Mudryi, A. V.; Martin, R. W.

    2016-03-01

    CuInSe2 single crystals ion implanted with 5 keV hydrogen at doses from 3  ×  1014 to 1016 cm-2 are studied by photoluminescence (PL). The PL spectra before and after implantation reveal two bands, a main dominant band centred at 0.96 eV and a lower intensity band centred at 0.93 eV. Detailed analysis of the shape of these bands, their temperature and excitation intensity dependencies allow the recombination mechanisms to be identified as band-to-tail (BT) and band-to-impurity (BI), respectively. The implantation causes gradual red shifts of the bands increasing linearly with the dose. The average depth of potential fluctuations is also estimated to increase with the dose and saturates for doses above 1015 cm-2. A model is proposed which associates the potential fluctuations with the antisite defects copper on indium site and indium on copper site. The saturation is explained by full randomization of copper and indium atoms on the cation sub-lattice.

  11. Theoretical studies of spin-Hamiltonian parameters of Mo5+ ion doped in K2SnCl6 crystal

    NASA Astrophysics Data System (ADS)

    Fang, Wang; Yang, Da-Xiao; Chen, Heng-Jie; Tang, Hai-Yan

    2013-11-01

    The spin-Hamiltonian (SH) parameters (g factors g//, g⊥ and hyperfine structure constants A//, A⊥ ) of K2SnCl6: Mo5+ (4d1) crystal are theoretically studied by the use of two microscopic spin-Hamiltonian (SH) methods, the high-order perturbation theory method (PTM) and the complete diagonalization (of energy matrix) method (CDM) within the molecular orbital (MO) scheme. The contributions arising both from the crystal field and charge transfer excitations are taken into account. The investigations show that the charge transfer mechanism plays a decisive role in the understanding of the spin-Hamiltonian (SH) parameters for 4d1 ions in crystals with the strong coordinate covalence, especially for g//>g⊥ which cannot be explained in the frame work of traditional crystal field approximation (CFA). The local defect structure around Mo5+ impurity ion center is determined to be D4 h point group symmetry.

  12. Ion Size Effect on Glow Peak Temperature in Dielectric Binary Mixed Crystals Doped With Divalent Europium

    NASA Astrophysics Data System (ADS)

    Rodriguez-Mijangos, Ricardo; Perez-Salas, Raul

    2008-03-01

    Thermoluminiscence measurements at room temperature of ``beta'' irradiated divalent Europium doped binary mixed alkali halides with RbCl and KBr components at several concentrations x in molar fraction are carried out. The experiments have been carried out to identify the effect of composition in thermoluminiscense glow peaks. A typical glow peak has been distinguished for each composition. A linear dependence of its temperature on the composition x has been found. This is principally associated with the radii size change of halogen ions. Comparison with results in mixed KCl:KBr. KBr:RbBr and KCl:RbCl support that assertion.

  13. Non-linear mixing in coupled photonic crystal nanobeam cavities due to cross-coupling opto-mechanical mechanisms

    SciTech Connect

    Ramos, Daniel Frank, Ian W.; Deotare, Parag B.; Bulu, Irfan; Lončar, Marko

    2014-11-03

    We investigate the coupling between mechanical and optical modes supported by coupled, freestanding, photonic crystal nanobeam cavities. We show that localized cavity modes for a given gap between the nanobeams provide weak optomechanical coupling with out-of-plane mechanical modes. However, we show that the coupling can be significantly increased, more than an order of magnitude for the symmetric mechanical mode, due to optical resonances that arise from the interaction of the localized cavity modes with standing waves formed by the reflection from thesubstrate. Finally, amplification of motion for the symmetric mode has been observed and attributed to the strong optomechanical interaction of our hybrid system. The amplitude of these self-sustained oscillations is large enough to put the system into a non-linear oscillation regime where a mixing between the mechanical modes is experimentally observed and theoretically explained.

  14. Evolution of linear acoustic domains in a plane layer of a liquid crystal beyond the instability threshold

    NASA Astrophysics Data System (ADS)

    Kapustina, O. A.

    2015-05-01

    This work experimentally validates for the first time the adequacy of a model describing the abovethreshold dynamics of a system of acoustic linear domains appearing in a plane layer of a nematic liquid crystal under the action of an oscillating hydrodynamic flow induced by shear vibrations at frequencies of the audio range. Values of the domain period are determined at the threshold of the effect and above the threshold up to oscillation amplitudes corresponding to orientational turbulization of the medium in layers with a thickness of 10-80 μm at frequencies of 0.1-20 Hz. The domain period has been determined as a function of the amplitude and oscillation frequency at different values of the layer thickness.

  15. Spontaneous helix formation in non-chiral bent-core liquid crystals with fast linear electro-optic effect

    PubMed Central

    Sreenilayam, Sithara P.; Panarin, Yuri P.; Vij, Jagdish K.; Panov, Vitaly P.; Lehmann, Anne; Poppe, Marco; Prehm, Marko; Tschierske, Carsten

    2016-01-01

    Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (∼30 μs) grey-scale switching due to the deformation of the helix by the electric field. Even more importantly, defect-free alignment is easily achieved for the first time for a BC mesogen, thus providing potential use in large-scale devices with fast linear and thresholdless electro-optical response. PMID:27156514

  16. Spontaneous helix formation in non-chiral bent-core liquid crystals with fast linear electro-optic effect.

    PubMed

    Sreenilayam, Sithara P; Panarin, Yuri P; Vij, Jagdish K; Panov, Vitaly P; Lehmann, Anne; Poppe, Marco; Prehm, Marko; Tschierske, Carsten

    2016-01-01

    Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (∼30 μs) grey-scale switching due to the deformation of the helix by the electric field. Even more importantly, defect-free alignment is easily achieved for the first time for a BC mesogen, thus providing potential use in large-scale devices with fast linear and thresholdless electro-optical response. PMID:27156514

  17. Spontaneous helix formation in non-chiral bent-core liquid crystals with fast linear electro-optic effect

    NASA Astrophysics Data System (ADS)

    Sreenilayam, Sithara P.; Panarin, Yuri P.; Vij, Jagdish K.; Panov, Vitaly P.; Lehmann, Anne; Poppe, Marco; Prehm, Marko; Tschierske, Carsten

    2016-05-01

    Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (~30 μs) grey-scale switching due to the deformation of the helix by the electric field. Even more importantly, defect-free alignment is easily achieved for the first time for a BC mesogen, thus providing potential use in large-scale devices with fast linear and thresholdless electro-optical response.

  18. Identification of the sulfoxide functionality in protonated analytes via ion/molecule reactions in linear quadrupole ion trap mass spectrometry.

    PubMed

    Sheng, Huaming; Williams, Peggy E; Tang, Weijuan; Zhang, Minli; Kenttämaa, Hilkka I

    2014-09-01

    A mass spectrometric method utilizing gas-phase ion/molecule reactions of 2-methoxypropene (MOP) has been developed for the identification of the sulfoxide functionality in protonated analytes in a LQIT mass spectrometer. Protonated sulfoxide analytes react with MOP to yield an abundant addition product (corresponding to 37-99% of the product ions), which is accompanied by a much slower proton transfer. The total efficiency (percent of gas-phase collisions leading to products) of the reaction is moderate (3-14%). A variety of compounds with different functional groups, including sulfone, hydroxylamino, N-oxide, aniline, phenol, keto, ester, amino and hydroxy, were examined to probe the selectivity of this reaction. Most of the protonated compounds with proton affinities lower than that of MOP react mainly via proton transfer to MOP. The formation of adduct-MeOH ions was found to be characteristic for secondary N-hydroxylamines. N-Oxides formed abundant MOP adducts just like sulfoxides, but sulfoxides can be differentiated from N-oxides based on their high reaction efficiencies. The reaction was tested by using the anti-inflammatory drug sulindac (a sulfoxide) and its metabolite sulindac sulfone. The presence of a sulfoxide functionality in the drug but a sulfone functionality in the metabolite was readily demonstrated. The presence of other functionalities in addition to sulfoxide in the analytes was found not to influence the diagnostic reactivity. PMID:24968187

  19. Present status and probable future capabilities of heavy-ion linear accelerators

    SciTech Connect

    Bollinger, L.M.

    1984-04-30

    The general characteristics of heavy-ion linacs are summarized, with emphasis on the similarities and differences of systems based on different technologies. The main design considerations of superconducting linacs are outlined, the many projects based on this technology are listed, and a new concept for a superconducting injector linac is described. The role of RFQ structures for heavy-ion acceleration is summarized. A concluding section lists some probable applications of heavy-ion accelerators during the next decade. 17 references, 5 figures, 1 table.

  20. Needle-like ion-doped hydroxyapatite crystals influence osteogenic properties of PCL composite scaffolds.

    PubMed

    Guarino, V; Veronesi, F; Marrese, M; Giavaresi, G; Ronca, A; Sandri, M; Tampieri, A; Fini, M; Ambrosio, Luigi

    2016-02-01

    Surface topography and chemistry both play a crucial role on influencing cell response in 3D porous scaffolds in terms of osteogenesis. Inorganic materials with peculiar morphology and chemical functionalities may be proficiently used to improve scaffold properties-in the bulk and along pore surface-promoting in vitro and in vivo osseous tissue in-growth. The present study is aimed at investigating how bone regenerative properties of composite scaffolds made of poly(Ɛ-caprolactone) (PCL) can be augmented by the peculiar properties of Mg(2+) ion doped hydroxyapatite (dHA) crystals, mainly emphasizing the role of crystal shape on cell activities mediated by microstructural properties. At the first stage, the study of mechanical response by crossing experimental compression tests and theoretical simulation via empirical models, allow recognizing a significant contribution of dHA shape factor on scaffold elastic moduli variation as a function of the relative volume fraction. Secondly, the peculiar needle-like shape of dHA crystals also influences microscopic (i.e. crystallinity, adhesion forces) and macroscopic (i.e. roughness) properties with relevant effects on biological response of the composite scaffold: differential scanning calorimetry (DSC) analyses clearly indicate a reduction of crystallization heat-from 66.75 to 43.05 J g(-1)-while atomic force microscopy (AFM) ones show a significant increase of roughness-from (78.15  ±  32.71) to (136.13  ±  63.21) nm-and of pull-off forces-from 33.7% to 48.7%. Accordingly, experimental studies with MG-63 osteoblast-like cells show a more efficient in vitro secretion of alkaline phosphatase (ALP) and collagen I and a more copious in vivo formation of new bone trabeculae, thus suggesting a relevant role of dHA to support the main mechanisms involved in bone regeneration. PMID:26928781

  1. Ion-pair complexes with strong near infrared absorbance: syntheses, crystal structures and spectroscopic properties.

    PubMed

    Pei, Wen-Bo; Wu, Jian-Sheng; Liu, Jian-Lan; Ren, Xiao-Ming; Shen, Lin-Jiang

    2010-01-01

    Three ion-pair complexes, [4-NH(2)-Py](2)[M(mnt)(2)] (4-NH(2)-Py(1+)=4-amino-pyridinium; mnt(2-)=maleonitriledithiolate; M=Pt (1), Pd (2) or Ni (3)), have been synthesized and characterized. In the crystal of 1, the strong H-bonding interaction was found from the protonated N-atom of pyridinium to the CN group of [Pt(mnt)(2)](2-) together with a weak Pt...H interaction between the anion and the cation. The crystals of 2 and 3 are isostructural with very similar lattice parameters and packing structures, which are distinct from the crystal of 1. Two kinds of strong H-bonding interactions are observed in the crystals of 2 and 3 between the CN groups of [M(mnt)(2)](2-) anion and the protonated N-atom of 4-NH(2)-Py(1+) cation as well as the CN groups of [M(mnt)(2)](2-) anion and the amino group of 4-NH(2)-Py(1+) cation. Complex 1 shows an intense near-IR absorbance in acetonitrile and solid state, such an absorption band is probably assigned to IPCT transition as well as a trace amount of [Pt(mnt)(2)](1-) species; complex 3 possesses a weak near-IR absorption band which can be attributed to the mixture of d-d transition in [Ni(mnt)(2)](2-) and IPCT transition as well as a trace amount of [Ni(mnt)(2)](1-) species. PMID:19897406

  2. Influence of yttrium content on the location of rare earth ions in LYSO:Ce crystals

    SciTech Connect

    Ding, Dongzhou; Weng, Linhong; Yang, Jianhua; Ren, Guohao; Wu, Yuntao

    2014-01-15

    Single-crystal X-ray diffraction (SCD), X-ray fluorescence (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray excited luminescence (XEL) measurements were performed to investigate structure details and segregation coefficients of (Lu{sub 1−x}Y{sub x}){sub 2}SiO{sub 5}:Ce (x=0 at%, 8.7 at%, 25.7 at%, 44.7 at%, 65.7 at%, 87.9 at% and 100 at%). Y{sup 3+} cations were found to have a preferential occupation for RE1 site (7-oxygen-coordinated) over RE2 site (6-oxygen-coordinated), which results in a greater increase of cell parameter c than that of a with increase in Y content due to LYSO's microstructure characteristics. Results presented here revealed that the less the difference in electronegativity and effective ionic radius between the two ions, the easier substitution of one ion by the other, and hence the higher segregation coefficients. Besides, the contribution of luminescence of Ce1 and Ce2 in the whole XEL was evaluated, and the location of Ce{sup 3+} ion was discussed. - Graphical abstract: Segregation coefficients of (Lu{sub 1−x}Y{sub x}){sub 2}SiO{sub 5}:Cce:italic> at RT/ce:italic>. Display Omitted.

  3. Optical detection of a single rare-earth ion in a crystal

    PubMed Central

    Kolesov, R.; Xia, K.; Reuter, R.; Stöhr, R.; Zappe, A.; Meijer, J.; Hemmer, P.R.; Wrachtrup, J.

    2012-01-01

    Rare-earth-doped laser materials show strong prospects for quantum information storage and processing, as well as for biological imaging, due to their high-Q 4f↔4f optical transitions. However, the inability to optically detect single rare-earth dopants has prevented these materials from reaching their full potential. Here we detect a single photostable Pr3+ ion in yttrium aluminium garnet nanocrystals with high contrast photon antibunching by using optical upconversion of the excited state population of the 4f↔4f optical transition into ultraviolet fluorescence. We also demonstrate on-demand creation of Pr3+ ions in a bulk yttrium aluminium garnet crystal by patterned ion implantation. Finally, we show generation of local nanophotonic structures and cell death due to photochemical effects caused by upconverted ultraviolet fluorescence of praseodymium-doped yttrium aluminium garnet in the surrounding environment. Our study demonstrates versatile use of rare-earth atomic-size ultraviolet emitters for nanoengineering and biotechnological applications. PMID:22929786

  4. Optical detection of a single rare-earth ion in a crystal

    NASA Astrophysics Data System (ADS)

    Kolesov, R.; Xia, K.; Reuter, R.; Stöhr, R.; Zappe, A.; Meijer, J.; Hemmer, P. R.; Wrachtrup, J.

    2012-08-01

    Rare-earth-doped laser materials show strong prospects for quantum information storage and processing, as well as for biological imaging, due to their high-Q 4f↔4f optical transitions. However, the inability to optically detect single rare-earth dopants has prevented these materials from reaching their full potential. Here we detect a single photostable Pr3+ ion in yttrium aluminium garnet nanocrystals with high contrast photon antibunching by using optical upconversion of the excited state population of the 4f↔4f optical transition into ultraviolet fluorescence. We also demonstrate on-demand creation of Pr3+ ions in a bulk yttrium aluminium garnet crystal by patterned ion implantation. Finally, we show generation of local nanophotonic structures and cell death due to photochemical effects caused by upconverted ultraviolet fluorescence of praseodymium-doped yttrium aluminium garnet in the surrounding environment. Our study demonstrates versatile use of rare-earth atomic-size ultraviolet emitters for nanoengineering and biotechnological applications.

  5. Linear and nonlinear optical properties of Na3La2(BO3)3 crystal

    NASA Astrophysics Data System (ADS)

    Li, Kai; Zhang, Guochun; Guo, Shu; Zhang, Xin; He, Ran; Zhang, Jianxiu; Lin, Zheshuai; Wu, Yicheng

    2013-12-01

    A 30×20×8 mm3 Na3La2(BO3)3 crystal has been grown by the top-seeded solution growth method (TSSG) using Na2O-B2O3-NaF as flux. The refractive indices at thirteen wavelengths from 0.2537 to 2.325 μm were accurately measured by the minimum deviation method, and the Sellmeier equations were accordingly constructed. The nonlinear optical (NLO) coefficients were measured by the Maker fringe method, which gave results of d31=1.45 pm/V, d32=0.67 pm/V, and d33=-1.06 pm/V, respectively. For second-harmonic generation (SHG) of 1064 nm, the effective NLO coefficient (deff) of type I phase-matching reaches the maximum value (1.44 pm/V) at the phase-matching angles θ=77.0°, ϕ=212.1°, which is larger than that of LiB3O5 (LBO). First-principle calculations suggest that Na3La2(BO3)3 possesses two types of NLO-active atom groups, BO3 group with π-orbital system and La-centered polyhedron with large polar displacement, of which the latter could be considered as a new type of NLO-active atom group.

  6. Polymer-Ion Interaction Weakens the Strain-Rate Dependence of Extension-Induced Crystallization for Poly(ethylene oxide).

    PubMed

    Hu, Tingting; Tian, Nan; Ali, Sarmad; Wang, Zhen; Chang, Jiarui; Huang, Ningdong; Li, Liangbin

    2016-03-01

    The crystallization of poly(ethylene oxide) (PEO)-sodium iodine (NaI) composites is investigated by differential scanning calorimetry (DSC), extensional rheology, and in situ small-angle X-ray scattering (SAXS) with the aim of demonstrating versatile roles played by polymer-ion interactions. In the isothermal quiescent crystallization process, a decrease in the crystal growth rate is observed for PEO-NaI and is attributed to slow chain movement caused by the coordination between cations and polymer. In situ SAXS on extensional flow-induced crystallization (FIC) exhibits enhanced kinetics and orientation for both PEO and PEO-NaI with increasing strain rate. However, an overall weaker strain-rate dependence of FIC is observed for PEO-NaI, which can be interpreted as a synergistic consequence of promoted nucleation under flow and impeded crystal growth by polymer-ion interaction. A possible microscopic mechanism is proposed to account for the experimental observation based on the formation of transient cross-linking points in PEO-NaI and their influence on the entanglement network of polymer under various flow fields. The disclosed strain-rate dependence and various ion effects on the behavior of PEO-salt composites contribute to a comprehensive understanding of polymer-ion solid polyelectrolytes. PMID:26822166

  7. Probabilities for nonradiative intermultiplet transitions in the holmium ion in lithium-yttrium double fluoride crystals and stimulated emission

    SciTech Connect

    Tkachuk, A.M.; Khilko, A.V.; Petrov, M.V.

    1985-02-01

    Nonradiative transition probabilities have been studied as functions of the energy difference between the closest-lying multiplets of the Ho/sup 3 +/ ion in the LiYF/sub 4/ crystal. The efficiencies of emission from terms of the holmium ion have been determined. The cross sections for stimulated emission for emission lines corresponding to the transition /sup 5/S/sub 2/ ..-->.. /sup 5/I/sub 7/ have also been determined. Some characteristics of the stimulated emission of LiYF/sub 4/:Ho/sup 3 +/ crystals are reported for several wavelengths in the 0.75--3.9-..mu..m spectral interval.

  8. Theoretical and experimental studies of the molecular orbital bonding coefficients for Cu2+ ion in cesium hydrogen oxalate single crystals

    NASA Astrophysics Data System (ADS)

    Kalfaoǧlu, Emel; Karabulut, Bünyamin

    2016-03-01

    Electron paramagnetic resonance (EPR) and optical absorption spectra of Cu2+ ions in cesium hydrogen oxalate single crystals have been investigated at room temperature. The spin-Hamiltonian parameters (g and A), have been determined. Crystalline field around the Cu2+ ion is almost axially symmetric. The results show a single paramagnetic site which confirms the triclinic crystal symmetry. Molecular orbital bonding coefficients are studied from the EPR and optical data. Theoretical octahedral field parameter and the tetragonal field parameters have been evaluated from the superposition model. Using these parameters, various bonding parameters are analyzed and the nature of bonding in the complex is discussed. The theoretical results are supported by experimental results.

  9. Two Active Site Divalent Ions in the Crystal Structure of the Hammerhead Ribozyme Bound to a Transition State Analogue.

    PubMed

    Mir, Aamir; Golden, Barbara L

    2016-02-01

    The crystal structure of the hammerhead ribozyme bound to the pentavalent transition state analogue vanadate reveals significant rearrangements relative to the previously determined structures. The active site contracts, bringing G10.1 closer to the cleavage site and repositioning a divalent metal ion such that it could, ultimately, interact directly with the scissile phosphate. This ion could also position a water molecule to serve as a general acid in the cleavage reaction. A second divalent ion is observed coordinated to O6 of G12. This metal ion is well-placed to help tune the pKA of G12. On the basis of this crystal structure as well as a wealth of biochemical studies, we propose a mechanism in which G12 serves as the general base and a magnesium-bound water serves as a general acid. PMID:26551631

  10. Energy transfer and non-linear optical properties at near ultraviolet wavelengths: Rare earth 4f yields 5d transitions in crystals and glasses

    NASA Astrophysics Data System (ADS)

    Hamilton, D. S.

    1992-08-01

    The following topics were studied: two-photon transitions from 4f ground state to 5d excited states in Ce(3+):CaF2; optical absorption and photoionization measurements from excited state of Ce(3+):Y3Al5O12; excited state photoionization of Ce(3+) ions in Ce(3+):CaF2; optical gain and loss studies in Ce(3+):LiYF4; Gd yields Cr energy transfer in Cr(3+):GSGG, Cr(3+):GSAG, and Cr(3+):GGG crystals; nonradiative relaxation in Ce(3+) doped crystals and glasses; and grating formation in impurity doped crystals.

  11. Crystal free-ion energy level analysis of Er 3+ (4f 11) in various crystal hosts-oxygen coordinated systems

    NASA Astrophysics Data System (ADS)

    Rukmini, E.; Renuka Devi, A.; Jayasankar, C. K.

    1994-02-01

    Comparative analyses of the Er 3+ (4f 11) crystal free-ion energy level structures in the Er 2O 3, Sc 2O 3, Y 2O 3, YAlO 3, GdAlO 3, SrMoO 4, ThGeO 4, CaWO 4, YVO 4, LuPO 4, Er(OH) 3, ErCl 3·6H 2O, Er(C 2H 5SO 4) 3 ·9H 2O, Na 3[Er(Oxydiacetate) 3]2NaClO 4·6H 2O and Er(HCOO) 3·2H 2O systems are reported. These analyses are based on a uniform model Hamiltonian that includes 20 free-ion parameters which are defined as central field ( EAVG), two-body electrostatic repulsion ( F2,4,6), two-body configuration (α, β, γ), three-body configuration ( T2,3,4,6,7,8), spin-orbit (ξ), spin-other-orbit ( M0,2,4) and electrostatically correlated spin-orbit ( P2,4,6) interactions. The systematic theoretical analysis of crystal free-ion levels results in a good correlation between calculated and observed energies. For example, comparison between the observed and calculated crystal free-ion levels of 13(Er:GdAlO 3), 8(Er:YVO 4), 8(Er:LuPO 4) and 11(Er:ErES) yields RMS deviations of 12 cm -1, 2 cm -1, 4 cm -1 and 7 cm -1 respectively. The empirical crystal free-ion energy parameters derived from fitting experimental data with the model Hamiltonian are consistent. The effects of the crystalline hosts on the empirical parameters are examined.

  12. Ion pairs of crystal violet in sodium bis(2-ethylhexyl)sulfosuccinate reverse micelles.

    PubMed

    Oliveira, Carla S; Bastos, Erick L; Duarte, Evandro L; Itri, Rosangela; Baptista, Mauricio S

    2006-10-10

    The interfacial localization and the ion pair formation of the positively charged dye crystal violet (CV) in sodium bis(2-ethylhexyl)sulfosuccinate reverse micelles (AOT RMs) were studied by several structural and spectroscopic techniques and by quantum chemical calculations. The size and shape of the AOT RMs in the presence of CV were investigated by small-angle X-ray scattering, showing that CV does not significantly change the RM structure. CV localization as a function of the water to surfactant molar ratio (w(0)) was characterized by H(1) and (13)C NMR, indicating the close proximity of CV to the sulfosuccinate group of AOT at small and large w(0) values. These results were confirmed by calculation of magnetic shielding constants using the gauge-independent atomic orbital method with the HF/6-31G(d) basis set. Two different types of ion pairs between AOT and CV, i.e., contact ion pair (CIPs) and solvent-separated ion pair (SSIPs), were characterized by UV-vis spectroscopy and quantum chemical calculations using the semiempirical ZINDO-CI method. In nonpolar isotropic solvents CIPs are formed with an association constant (K(ASSOC)) of 2 x 10(4) mol(-1) L in isooctane and 750 mol(-1) L in chloroform. In AOT RMs at low w(0), CV-AOT CIPs are also formed. By increasing w(0), there is a sharp decrease in the CIP association free energy, and SSIPs are formed. (CV(+))(H(2)O)(AOT(-)) SSIPs are stable in the AOT RM up to the largest w(0) tested (w(0) = 33). PMID:17014109

  13. Identification of 2-aminothiazolobenzazepine metabolites in human, rat, dog, and monkey microsomes by ion-molecule reactions in linear quadrupole ion trap mass spectrometry.

    PubMed

    Zhang, Minli; Eismin, Ryan; Kenttämaa, Hilkka; Xiong, Hui; Wu, Ye; Burdette, Doug; Urbanek, Rebecca

    2015-03-01

    2-Aminothiazolobenzazepine (2-ATBA), 7-[(1-methyl-1H-pyrazol-4-yl)methyl]-6,7,8,9-tetrahydro-5H-[1,3]thiazolo[4,5-h][3]benzazepin-2-amine, is a D2 partial agonist that has demonstrated antipsychotic effects in a rodent in vivo efficacy model. The metabolite profile showed that 2-ATBA is mainly metabolized by oxidation. However, identification of the oxidation site(s) in the 2-aminothiazole group presents a challenge for the traditional metabolite identification methods such as liquid chromatography/mass spectrometry and NMR due to the lack of unique tandem mass spectrometry fragmentation patterns for ions with the 2-aminothiazole group oxidized at different sites and the lack of stability for purification or reference standard synthesis. We describe the characterization of the oxidized heteroatoms of the 2-aminothiazole group via gas-phase ion-molecule reactions (GPIMR) in a modified linear quadrupole ion trap mass spectrometer. The GPIMR reagents used were dimethyl disulfide, tert-butyl peroxide, and tri(dimethylamino)borane. Each reagent was introduced into the ion trap through the helium line and was allowed to react with the protonated metabolites. The ionic ion-molecule reaction products and their fragmentation profiles were compared with the profiles of the ionic ion-molecule reaction products of protonated reference compounds that had specific heteroatom functionalities. The oxidized 2-aminothiazole metabolite of 2-ATBA showed a similar GPIMR profile to that of the reference compounds with a tertiary N-oxide functionality and distinct from the profiles of the reference compounds with N-aryl hydroxylamine, nitroso, or pyridine N-oxide functionalities. This study demonstrates the feasibility of fingerprinting the chemical nature of oxidized nitrogen functional groups via GPIMR profiling for metabolite structure elucidation. PMID:25547868

  14. Influence of other rare earth ions on the optical refrigeration efficiency in Yb:YLF crystals.

    PubMed

    Di Lieto, Alberto; Sottile, Alberto; Volpi, Azzurra; Zhang, Zhonghan; Seletskiy, Denis V; Tonelli, Mauro

    2014-11-17

    We investigated the effect of rare earth impurities on the cooling efficiency of Yb³⁺:LiYF₄ (Yb:YLF). The refrigeration performance of two single crystals, doped with 5%-at. Yb and with identical history but with different amount of contaminations, have been compared by measuring the cooling efficiency curves. Spectroscopic and elemental analyses of the samples have been carried out to identify the contaminants, to quantify their concentrations and to understand their effect on the cooling efficiencies. A model of energy transfer processes between Yb and other rare earth ions is suggested, identifying Erbium and Holmium as elements that produce a detrimental effect on the cooling performance. PMID:25402099

  15. Incorporation of copper ions into crystals of T2 copper-depleted laccase from Botrytis aclada

    PubMed Central

    Osipov, E. M.; Polyakov, K. M.; Tikhonova, T. V.; Kittl, R.; Dorovatovskii, P.V.; Shleev, S. V.; Popov, V. O.; Ludwig, R.

    2015-01-01

    Laccases belong to the class of multicopper oxidases catalyzing the oxidation of phenols accompanied by the reduction of molecular oxygen to water without the formation of hydrogen peroxide. The activity of laccases depends on the number of Cu atoms per enzyme molecule. The structure of type 2 copper-depleted laccase from Botrytis aclada has been solved previously. With the aim of obtaining the structure of the native form of the enzyme, crystals of the depleted laccase were soaked in Cu+- and Cu2+-containing solutions. Copper ions were found to be incorporated into the active site only when Cu+ was used. A comparative analysis of the native and depleted forms of the enzymes was performed. PMID:26625287

  16. Incorporation of copper ions into crystals of T2 copper-depleted laccase from Botrytis aclada.

    PubMed

    Osipov, E M; Polyakov, K M; Tikhonova, T V; Kittl, R; Dorovatovskii, P V; Shleev, S V; Popov, V O; Ludwig, R

    2015-12-01

    Laccases belong to the class of multicopper oxidases catalyzing the oxidation of phenols accompanied by the reduction of molecular oxygen to water without the formation of hydrogen peroxide. The activity of laccases depends on the number of Cu atoms per enzyme molecule. The structure of type 2 copper-depleted laccase from Botrytis aclada has been solved previously. With the aim of obtaining the structure of the native form of the enzyme, crystals of the depleted laccase were soaked in Cu(+)- and Cu(2+)-containing solutions. Copper ions were found to be incorporated into the active site only when Cu(+) was used. A comparative analysis of the native and depleted forms of the enzymes was performed. PMID:26625287

  17. Photo-luminescence studies of strontium barium niobate crystals doped with Cr 3+ ions

    NASA Astrophysics Data System (ADS)

    Han, T. P. J.; Jaque, F.; Jaque, D.; Ivleva, L.

    2006-01-01

    This paper reports the photo-luminescence spectroscopic results of Strontium-Barium-Niobate, Sr x,Ba 1- xNb 2O 5 (SBN, x = 0.61 for near congruent composition) crystals doped with Cr 2O, at cryogenic temperature (20 K). The experimental results reveal the need of re-assignment of the Cr 3+ ions defect centres in this material. For first time, a broad emission band in the near infrared region centred at ca. 950 nm is reported. This emission band has micro-seconds decaytime constant and a FWHM band-width > 1700 cm -1 and has been ascribed to the vibronically assisted 4T 2 → 4A 2 transition. A much narrower emission band centred at ca. 764 nm with milli-seconds decaytime constant and a FWHM band-width of ca. 170 cm -1 is correlated to the 2E → 4A 2 radiative transition (R-line).

  18. Lithium ion diffusion in Li β-alumina single crystals measured by pulsed field gradient NMR spectroscopy

    SciTech Connect

    Chowdhury, Mohammed Tareque Takekawa, Reiji; Iwai, Yoshiki; Kuwata, Naoaki; Kawamura, Junichi

    2014-03-28

    The lithium ion diffusion coefficient of a 93% Li β-alumina single crystal was measured for the first time using pulsed field gradient (PFG) NMR spectroscopy with two different crystal orientations. The diffusion coefficient was found to be 1.2 × 10{sup −11} m{sup 2}/s in the direction perpendicular to the c axis at room temperature. The Li ion diffusion coefficient along the c axis direction was found to be very small (6.4 × 10{sup −13} m{sup 2}/s at 333 K), which suggests that the macroscopic diffusion of the Li ion in the β-alumina crystal is mainly two-dimensional. The diffusion coefficient for the same sample was also estimated using NMR line narrowing data and impedance measurements. The impedance data show reasonable agreement with PFG-NMR data, while the line narrowing measurements provided a lower value for the diffusion coefficient. Line narrowing measurements also provided a relatively low value for the activation energy and pre-exponential factor. The temperature dependent diffusion coefficient was obtained in the temperature range 297–333 K by PFG-NMR, from which the activation energy for diffusion of the Li ion was estimated. The activation energy obtained by PFG-NMR was smaller than that obtained by impedance measurements, which suggests that thermally activated defect formation energy exists for 93% Li β-alumina single crystals. The diffusion time dependence of the diffusion coefficient was observed for the Li ion in the 93% Li β-alumina single crystal by means of PFG-NMR experiments. Motion of Li ion in fractal dimension might be a possible explanation for the observed diffusion time dependence of the diffusion coefficient in the 93% Li β–alumina system.

  19. Exclusive Stereocomplex Crystallization of Linear and Multiarm Star-Shaped High-Molecular-Weight Stereo Diblock Poly(lactic acid)s.

    PubMed

    Han, Lili; Shan, Guorong; Bao, Yongzhong; Pan, Pengju

    2015-11-01

    Linear, 3-arm, and 6-arm star-shaped stereo diblock copolymers of l- and d-lactic acid (PLLA-b-PDLA) with high molecular weights (MWs) were synthesized via two-step ring-opening polymerization (ROP) with 1-dodechanol, glycerol, and d-sorbitol as the initiators, respectively. The chemical structure, nonisothermal and isothermal crystallization kinetics, crystalline structure, lamellar morphology, and mechanical thermal properties of PLLA-b-PDLAs with different macromolecular topologies were investigated. Compared to the high-molecular-weight (MW) poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) racemic blends, PLLA-b-PDLAs exhibit faster crystallization upon cooling and isothermal melt crystallization; they crystallize exclusively in stereocomplex (sc) crystallites under all of the conditions investigated. This is attributable to the enhanced interactions between enantiomeric blocks linked covalently. Macromolecular topology influences the crystallization kinetics and crystalline structure of PLLA-b-PDLAs significantly. The crystallization temperature upon cooling, melting temperature, degree of crystallinity, spherulitic growth rate, crystallite size, long period, and crystalline layer thickness of PLLA-b-PDLA decrease with increasing branching number because of the retarding effect of branching on the crystallization rate and crystallizability. Because of the formation of high-melting-point sc crystallites, both the linear and star-shaped PLLA-b-PDLAs exhibit better thermal resistance and higher storage moduli at high temperature than does homocrystalline PLLA. PMID:26457767

  20. Performance of MBE-4: An experimental multiple beam induction linear accelerator for heavy ions

    SciTech Connect

    Warwick, A.I.; Fessenden, T.J.; Keefe, D.; Kim, C.H.; Meuth, H.

    1988-06-01

    An experimental induction linac, called MBE-4, has been constructed to demonstrate acceleration and current amplification of multiple heavy ion beams. This work is part of a program to study the use of such an accelerator as a driver for heavy ion inertial fusion. MBE-4 is 16m long and accelerates four space-charge-dominated beams of singly-charged cesium ions, in this case from 200 keV to 700 keV, amplifying the current in each beam from 10mA by a factor of nine. Construction of the experiment was completed late in 1987 and we present the results of detailed measurements of the longitudinal beam dynamics. Of particular interest is the contribution of acceleration errors to the growth of current fluctuations and to the longitudinal emittance. The effectiveness of the longitudinal focusing, accomplished by means of the controlled time dependence of the accelerating fields, is also discussed. 4 refs., 5 figs., 1 tab.

  1. Study of the beam breakup mode in linear induction accelerators for heavy ions

    SciTech Connect

    Chattopadhyay, S.; Faltens, A.; Smith, L.

    1981-03-01

    A simple theoretical study and numerical estimate is presented for the transverse amplitude growth of a nonrelativistic heavy ion beam in an induction linac, as envisaged for use in commercial power plants, due to the nonregenerative coherent beam breakup mode. An equivalent electrical circuit has been used to represent the accelerating induction modules. Our calculation shows that for the parameters of interest, the beam breakup amplitude for a heavy ion beam grows extremely slowly in the time scales of interest, to magnitudes insignificant for transport purposes. It is concluded that the coherent beam breakup mode does not pose any serious threat to the stability of a high current (kA) heavy ion beam in an induction linac.

  2. Non-linear resonance of fluids in a crystal growth cavity

    NASA Technical Reports Server (NTRS)

    Wang, Francis C.

    1996-01-01

    In the microgravity environment, the effect of gravity on fluid motion is much reduced. Hence, secondary effects such as vibrations, jitters, surface tension, capillary effects, and electromagnetic forces become the dominant mechanism of fluid convection. Numerous studies have been conducted to investigate fluid behavior in microgravity with the ultimate goal of developing processes with minimal influence from convection. Industrial applications such as crystal growth from solidification of melt and protein growth for pharmatheutical application are just a few examples of the vast potential benefit that can be reaped from material processing in space. However, a space laboratory is not immune from all undesirable disturbances and it is imperative that such disturbances be well understood, quantifiable, and controlled. Non-uniform and transient accelerations such as vibrations, jitters, and impulsive accelerations exist as a result of crew activities, space vehicle maneuvering, and the operations of on-board equipment. Measurements conducted on-board a U.S. Spacelab showed the existence of vibrations in the frequency range of 1 to 100 Hz with a dominant mode of 17 Hz and harmonics of 54 Hz. The observed vibration is not limited to any coordinate plane but exists in all directions. Similar situation exists on-board the Russian MIR space station. Due to the large structure of its design, the future International Space Station will have its own characteristic vibration spectrum. It is well known that vibration can exert substantial influence on heat and mass transfer processes, thus hindering any attempts to achieve a diffusion-limited process. Experiments on vibration convection for a liquid-filled enclosure under one-g environment showed the existence of different flow regimes as vibration frequency and intensity changes. Results showed the existence of a resonant frequency, near which the enhancement is the strongest, and the existence of a high frequency asymptote

  3. Investigation of thermal diffusivity dependence on temperature in a group of optical single crystals doped with rare earth ions

    NASA Astrophysics Data System (ADS)

    Trefon-Radziejewska, D.; Bodzenta, J.

    2015-07-01

    The group of YAG, YVO4 and GdCOB single crystals was examined to determine the thermal diffusivity as a function of temperature in range from 30 °C to 300 °C. Further investigations concerned on analysis of the influence of dopants on these dependencies. The experimental setup based on thermal wave method with mirage detection was used. The samples represented different crystallographic systems such as cubic (YAG) tetragonal (YVO4) and monoclinic (GdCOB). The anisotropy of thermal conductivity of investigated samples was taken into account in the investigations. The crystals were doped with calcium ions, rare earth ions such as ytterbium, neodymium, and thulium, and also with transition metal vanadium. The results confirmed that influence of doping on the thermal diffusivity of investigated materials strongly depends on temperature. In general the thermal diffusivity decreases with increasing of sample temperature from 30 °C to 300 °C, however the drop in thermal diffusivity is the highest for pure single crystals. Doping is another factor reducing the heat transport in single crystals. Introduction of dopant ions into a crystal lattice leads to a significant decrease in the thermal diffusivity at lower temperatures in comparison with pure crystals. However, the influence of dopants becomes less pronounced with increasing temperature, and in case of weakly doped crystals it becomes negligible at higher temperatures. The interpretation of thermal diffusivity dependence on temperature for single crystals was based on the Debye model of lattice thermal conductivity of solids. The results allowed to conclude that the decrease of thermal diffusivity with temperature and increasing concentration of impurities is caused by shortening of the phonons mean free path due to phonon-phonon and phonon-point defect scatterings.

  4. Monodisperse Colloidal Gallium Nanoparticles: Synthesis, Low Temperature Crystallization, Surface Plasmon Resonance and Li-Ion Storage

    PubMed Central

    2015-01-01

    We report a facile colloidal synthesis of gallium (Ga) nanoparticles with the mean size tunable in the range of 12–46 nm and with excellent size distribution as small as 7–8%. When stored under ambient conditions, Ga nanoparticles remain stable for months due to the formation of native and passivating Ga-oxide layer (2–3 nm). The mechanism of Ga nanoparticles formation is elucidated using nuclear magnetic resonance spectroscopy and with molecular dynamics simulations. Size-dependent crystallization and melting of Ga nanoparticles in the temperature range of 98–298 K are studied with X-ray powder diffraction, specific heat measurements, transmission electron microscopy, and X-ray absorption spectroscopy. The results point to delta (δ)-Ga polymorph as a single low-temperature phase, while phase transition is characterized by the large hysteresis and by the large undercooling of crystallization and melting points down to 140–145 and 240–250 K, respectively. We have observed size-tunable plasmon resonance in the ultraviolet and visible spectral regions. We also report stable operation of Ga nanoparticles as anode material for Li-ion batteries with storage capacities of 600 mAh g–1, 50% higher than those achieved for bulk Ga under identical testing conditions. PMID:25133552

  5. Toward measuring concentration gradients in polymer-dispersed liquid crystals with secondary ion mass spectrometry

    NASA Astrophysics Data System (ADS)

    Kjellander, B. K. Charlotte; van IJzendoorn, Leo J.; de Jong, Arthur M.; Broer, Dirk J.; van Gennip, Wouter J. H.; de Voigt, Martien J. A.; Niemantsverdriet, Hans J. W.

    2004-05-01

    Dynamic secondary ion mass spectrometry (SIMS) is usually applied to measure depth profiles in inorganic multi-layer systems. SIMS on organic multi-layer samples is highly complicated due to the complex fragmentation of the sample which results in fingerprint of masses representing the components in the sample. Using multivariate statistics, we succeeded to interpret the SIMS spectra and were able to identify layers with different compositions in artificially produced two-layer samples. The method is demonstrated for samples of a poly(isobornylmethacrylate) coating on a polymer dispersed liquid crystal consisting of the nematic liquid crystal (E7) and poly(isobornylmethacrylate). Quantification of the E7 concentration is complicated by evaporation in the vacuum system. Infrared spectroscopy proved that the loss of E7 from poly(isobornylmethacrylate) can be prevented by capping the sample with poly(vinyl alcohol). Cooling to cryogenic temperatures will be required to suppress further evaporation during SIMS analysis. The SIMS depth resolution of a two-layered sample was determined by discriminant function analysis to be 130 nm at a depth of one micrometer, which allows the application of SIMS for a typical optical grating.

  6. Characterization of phthiocerol and phthiodiolone dimycocerosate esters of M. tuberculosis by multiple-stage linear ion-trap MS.

    PubMed

    Flentie, Kelly N; Stallings, Christina L; Turk, John; Minnaard, Adriaan J; Hsu, Fong-Fu

    2016-01-01

    Both phthiocerol/phthiodiolone dimycocerosate (PDIM) and phenolic glycolipids are abundant virulent lipids in the cell wall of various pathogenic mycobacteria, which can synthesize a wide range of complex high-molecular-mass lipids. In this article, we describe linear ion-trap MS(n) mass spectrometric approach for structural study of PDIMs, which were desorbed as the [M + Li](+) and [M + NH(4)](+) ions by ESI. We also applied charge-switch strategy to convert the mycocerosic acid substituents to their N-(4-aminomethylphenyl) pyridinium (AMPP) derivatives and analyzed them as M (+) ions, following alkaline hydrolysis of the PDIM to release mycocerosic acids. The structural information from MS(n) on the [M + Li](+) and [M + NH(4)](+) molecular species and on the M (+) ions of the mycocerosic acid-AMPP derivative affords realization of the complex structures of PDIMs in Mycobacterium tuberculosis biofilm, differentiation of phthiocerol and phthiodiolone lipid families and complete structure identification, including the phthiocerol and phthiodiolone backbones, and the mycocerosic acid substituents, including the locations of their multiple methyl side chains, can be achieved. PMID:26574042

  7. Some Rare Earth Elements Analysis by Microwave Plasma Torch Coupled with the Linear Ion Trap Mass Spectrometry

    PubMed Central

    Xiong, Xiaohong; Jiang, Tao; Qi, Wenhao; Zuo, Jun; Yang, Meiling; Fei, Qiang; Xiao, Saijin; Yu, Aimin; Zhu, Zhiqiang; Chen, Huanwen

    2015-01-01

    A sensitive mass spectrometric analysis method based on the microwave plasma technique is developed for the fast detection of trace rare earth elements (REEs) in aqueous solution. The plasma was produced from a microwave plasma torch (MPT) under atmospheric pressure and was used as ambient ion source of a linear ion trap mass spectrometer (LTQ). Water samples were directly pneumatically nebulized to flow into the plasma through the central tube of MPT. For some REEs, the generated composite ions were detected in both positive and negative ion modes and further characterized in tandem mass spectrometry. Under the optimized conditions, the limit of detection (LOD) was at the level 0.1 ng/mL using MS2 procedure in negative mode. A single REE analysis can be completed within 2~3 minutes with the relative standard deviation ranging between 2.4% and 21.2% (six repeated measurements) for the 5 experimental runs. Moreover, the recovery rates of these REEs are between the range of 97.6%–122.1%. Two real samples have also been analyzed, including well and orange juice. These experimental data demonstrated that this method is a useful tool for the field analysis of REEs in water and can be used as an alternative supplement of ICP-MS. PMID:26421013

  8. Some Rare Earth Elements Analysis by Microwave Plasma Torch Coupled with the Linear Ion Trap Mass Spectrometry.

    PubMed

    Xiong, Xiaohong; Jiang, Tao; Qi, Wenhao; Zuo, Jun; Yang, Meiling; Fei, Qiang; Xiao, Saijin; Yu, Aimin; Zhu, Zhiqiang; Chen, Huanwen

    2015-01-01

    A sensitive mass spectrometric analysis method based on the microwave plasma technique is developed for the fast detection of trace rare earth elements (REEs) in aqueous solution. The plasma was produced from a microwave plasma torch (MPT) under atmospheric pressure and was used as ambient ion source of a linear ion trap mass spectrometer (LTQ). Water samples were directly pneumatically nebulized to flow into the plasma through the central tube of MPT. For some REEs, the generated composite ions were detected in both positive and negative ion modes and further characterized in tandem mass spectrometry. Under the optimized conditions, the limit of detection (LOD) was at the level 0.1 ng/mL using MS(2) procedure in negative mode. A single REE analysis can be completed within 2~3 minutes with the relative standard deviation ranging between 2.4% and 21.2% (six repeated measurements) for the 5 experimental runs. Moreover, the recovery rates of these REEs are between the range of 97.6%-122.1%. Two real samples have also been analyzed, including well and orange juice. These experimental data demonstrated that this method is a useful tool for the field analysis of REEs in water and can be used as an alternative supplement of ICP-MS. PMID:26421013

  9. Number-conserving linear-response study of low-velocity ion stopping in a collisional magnetized classical plasma

    SciTech Connect

    Nersisyan, Hrachya B.; Deutsch, Claude; Das, Amal K.

    2011-03-15

    The results of a theoretical investigation of the low-velocity stopping power of ions in a magnetized collisional and classical plasma are reported. The stopping power for an ion is calculated through the linear-response (LR) theory. The collisions, which lead to a damping of the excitations in the plasma, are taken into account through a number-conserving relaxation time approximation in the LR function. In order to highlight the effects of collisions and magnetic field, we present a comparison of our analytical and numerical results obtained for nonzero damping or magnetic field with those for vanishing damping or magnetic field. It is shown that the collisions remove the anomalous friction obtained previously [Nersisyan et al., Phys. Rev. E 61, 7022 (2000)] for the collisionless magnetized plasmas at low ion velocities. One of the major objectives of this paper is to compare and to contrast our theoretical results with those obtained through a diffusion coefficient formulation based on the Dufty-Berkovsky relation evaluated for a magnetized one-component plasma modeled with target ions and electrons.

  10. Near-LTE linear response calculations with a collisional-radiative model for He-like Al ions

    SciTech Connect

    More, R.M.; Kato, T.

    1998-01-06

    We investigate the non-equilibrium atomic kinetics using a collisional-radiative (CR) model modified to include line absorption. Steady-state emission is calculated for He-like aluminum ions immersed in a specified radiation field having fixed deviations from a Planck spectrum. The net emission is interpreted in terms of NLTE population changes. The calculation provides an NLTE response matrix, and in agreement with a general relation of non-equilibrium thermodynamics, the response matrix is symmetric. We compute the response matrix for 1% and 50% changes in the photon temperature and find linear response over a surprisingly large range.

  11. A perpendicular ion beam instability - Solutions to the linear dispersion relation. [for F region ionosphere

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Kelley, M. C.

    1983-01-01

    A 200-eV Xe(+) ion beam directed perpendicular to the terrestrial magnetic field in the F region ionosphere produced very narrow band electrostatic emissions just above multiples of the hydrogen cyclotron frequency. Although the plasma conditions associated with the ion beam were undoubtedly very complex, a simple ion beam in a background ionosphere is considered first. The dispersion relation for flute mode waves and an unmagnetized perpendicular ion beam is solved for a diffuse H(+) plasma and then for a combination of dense O(+) and diffuse H(+). These solutions account for most of the wave properties, including the observation of narrow spectral peaks separated by the hydrogen cyclotron frequency and the observation of no spectral peaks below 2000 Hz. We cannot dismiss field-aligned currents associated with the Xe(+) beam as an alternate source of free energy for the narrow band emissions. However, our intention here is to examine closely the Xe(+) beam as a source for directly exciting the plasma waves.

  12. Gyro-viscosity and linear dispersion relations in pair-ion magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Kono, M.; Vranjes, J.

    2015-11-01

    A fluid theory has been developed by taking account of gyro-viscosity to study wave propagation characteristics in a homogeneous pair-ion magnetized plasma with a cylindrical symmetry. The exact dispersion relations derived by the Hankel-Fourier transformation are shown comparable with those observed in the experiment by Oohara and co-workers. The gyro-viscosity is responsible for the change in propagation characteristics of the ion cyclotron wave from forward to backward by suppressing the effect of the thermal pressure which normally causes the forward nature of dispersion. Although the experiment has been already explained by a kinetic theory by the present authors, the kinetic derivations are so involved because of exact particle orbits in phase space, finite Lamor radius effects, and higher order ion cyclotron resonances. The present fluid theory provides a simple and transparent structure to the dispersion relations since the gyro-viscosity is renormalized into the ion cyclotron frequency which itself indicates the backward nature of dispersion. The usual disadvantage of a fluid theory, which treats only fundamental modes of eigen-waves excited in a system and is not able to describe higher harmonics that a kinetic theory does, is compensated by simple derivations and clear picture based on the renormalization of the gyro-viscosity.

  13. Back-streaming ion emission and beam focusing on high power linear induction accelerator

    NASA Astrophysics Data System (ADS)

    Zhu, Jun; Chen, Nan; Yu, Haijun; Jiang, Xiaoguo; Wang, Yuan; Dai, Wenhua; Gao, Feng; Wang, Minhong; Li, Jin; Shi, Jinshui

    2011-08-01

    Ions released from target surfaces by impact of a high intensity and current electron beam can be accelerated and trapped in the beam potential, and further destroy the beam focus. By solving the 2D Poisson equation, we found that the charge neutralization factor of the ions to the beam under space charge limited condition is 1/3, which is large enough to disrupt the spot size. Therefore, the ion emission at the target in a single-pulse beam/target system must be source limited. Experimental results on the time-resolved beam profile measurement have also proven that. A new focus scheme is proposed in this paper to focus the beam to a small spot size with the existence of back-streaming ions. We found that the focal spot will move upstream as the charge neutralization factor increases. By comparing the theoretical and experimental focal length of the Dragon-I accelerator (20 MeV, 2.5 kA, 60 ns flattop), we found that the average neutralization factor is about 5% in the beam/target system.

  14. Gyro-viscosity and linear dispersion relations in pair-ion magnetized plasmas

    SciTech Connect

    Kono, M.; Vranjes, J.

    2015-11-15

    A fluid theory has been developed by taking account of gyro-viscosity to study wave propagation characteristics in a homogeneous pair-ion magnetized plasma with a cylindrical symmetry. The exact dispersion relations derived by the Hankel-Fourier transformation are shown comparable with those observed in the experiment by Oohara and co-workers. The gyro-viscosity is responsible for the change in propagation characteristics of the ion cyclotron wave from forward to backward by suppressing the effect of the thermal pressure which normally causes the forward nature of dispersion. Although the experiment has been already explained by a kinetic theory by the present authors, the kinetic derivations are so involved because of exact particle orbits in phase space, finite Lamor radius effects, and higher order ion cyclotron resonances. The present fluid theory provides a simple and transparent structure to the dispersion relations since the gyro-viscosity is renormalized into the ion cyclotron frequency which itself indicates the backward nature of dispersion. The usual disadvantage of a fluid theory, which treats only fundamental modes of eigen-waves excited in a system and is not able to describe higher harmonics that a kinetic theory does, is compensated by simple derivations and clear picture based on the renormalization of the gyro-viscosity.

  15. Copper Ion from Cu2O Crystal Induces AMPK-Mediated Autophagy via Superoxide in Endothelial Cells.

    PubMed

    Seo, Youngsik; Cho, Young-Sik; Huh, Young-Duk; Park, Heonyong

    2016-03-31

    Copper is an essential element required for a variety of functions exerted by cuproproteins. An alteration of the copper level is associated with multiple pathological conditions including chronic ischemia, atherosclerosis and cancers. Therefore, copper homeostasis, maintained by a combination of two copper ions (Cu(+) and Cu(2+)), is critical for health. However, less is known about which of the two copper ions is more toxic or functional in endothelial cells. Cubic-shaped Cu2O and CuO crystals were prepared to test the role of the two different ions, Cu(+) and Cu(2+), respectively. The Cu2O crystal was found to have an effect on cell death in endothelial cells whereas CuO had no effect. The Cu2O crystals appeared to induce p62 degradation, LC3 processing and an elevation of LC3 puncta, important processes for autophagy, but had no effect on apoptosis and necrosis. Cu2O crystals promote endothelial cell death via autophagy, elevate the level of reactive oxygen species such as superoxide and nitric oxide, and subsequently activate AMP-activated protein kinase (AMPK) through superoxide rather than nitric oxide. Consistently, the AMPK inhibitor Compound C was found to inhibit Cu2O-induced AMPK activation, p62 degradation, and LC3 processing. This study provides insight on the pathophysiologic function of Cu(+) ions in the vascular system, where Cu(+) induces autophagy while Cu(2+) has no detected effect. PMID:26743904

  16. Copper Ion from Cu2O Crystal Induces AMPK-Mediated Autophagy via Superoxide in Endothelial Cells

    PubMed Central

    Seo, Youngsik; Cho, Young-Sik; Huh, Young-Duk; Park, Heonyong

    2016-01-01

    Copper is an essential element required for a variety of functions exerted by cuproproteins. An alteration of the copper level is associated with multiple pathological conditions including chronic ischemia, atherosclerosis and cancers. Therefore, copper homeostasis, maintained by a combination of two copper ions (Cu+ and Cu2+), is critical for health. However, less is known about which of the two copper ions is more toxic or functional in endothelial cells. Cubic-shaped Cu2O and CuO crystals were prepared to test the role of the two different ions, Cu+ and Cu2+, respectively. The Cu2O crystal was found to have an effect on cell death in endothelial cells whereas CuO had no effect. The Cu2O crystals appeared to induce p62 degradation, LC3 processing and an elevation of LC3 puncta, important processes for autophagy, but had no effect on apoptosis and necrosis. Cu2O crystals promote endothelial cell death via autophagy, elevate the level of reactive oxygen species such as superoxide and nitric oxide, and subsequently activate AMP-activated protein kinase (AMPK) through superoxide rather than nitric oxide. Consistently, the AMPK inhibitor Compound C was found to inhibit Cu2O-induced AMPK activation, p62 degradation, and LC3 processing. This study provides insight on the pathophysiologic function of Cu+ ions in the vascular system, where Cu+ induces autophagy while Cu2+ has no detected effect. PMID:26743904

  17. Perpendicular wavenumber dependence of the linear stability of global ion temperature gradient modes on E × B flows

    NASA Astrophysics Data System (ADS)

    Hill, P.; Saarelma, S.; McMillan, B.; Peeters, A.; Verwichte, E.

    2012-06-01

    Sheared E × B flows are known to stabilize turbulence. This paper investigates how the linear stability of the ion-temperature-gradient (ITG) mode depends on k⊥ in both circular and MHD geometry. We study the effects of both rotation profiles of constant shear and of purely toroidal flow taken from experiment, using the global gyrokinetic particle-in-cell code NEMORB. We find that in order to effectively stabilize the linear mode, the fastest growing mode requires a shearing rate (γE) around 1-2 times its linear growth rate without flow (γ0), while both longer and shorter wavelength modes need much larger flow shear compared with their static linear growth rates. Modes with kθρi < 0.2 need γE as much as 10 times their γ0. This variation exists in both large-aspect ratio circular cross-section and small-aspect ratio MHD geometries, with both analytic constant shear and experimental flow profiles. There is an asymmetry in the suppression with respect to the sign of γE, due to competition between equilibrium profile variation and flow shear. The maximum growth rate for cases using the experimental profile in MAST equilibria occurs at shearing rates of 10% the experimental level.

  18. Failure mechanisms of single-crystal silicon electrodes in lithium-ion batteries

    PubMed Central

    Shi, Feifei; Song, Zhichao; Ross, Philip N.; Somorjai, Gabor A.; Ritchie, Robert O.; Komvopoulos, Kyriakos

    2016-01-01

    Long-term durability is a major obstacle limiting the widespread use of lithium-ion batteries in heavy-duty applications and others demanding extended lifetime. As one of the root causes of the degradation of battery performance, the electrode failure mechanisms are still unknown. In this paper, we reveal the fundamental fracture mechanisms of single-crystal silicon electrodes over extended lithiation/delithiation cycles, using electrochemical testing, microstructure characterization, fracture mechanics and finite element analysis. Anisotropic lithium invasion causes crack initiation perpendicular to the electrode surface, followed by growth through the electrode thickness. The low fracture energy of the lithiated/unlithiated silicon interface provides a weak microstructural path for crack deflection, accounting for the crack patterns and delamination observed after repeated cycling. On the basis of this physical understanding, we demonstrate how electrolyte additives can heal electrode cracks and provide strategies to enhance the fracture resistance in future lithium-ion batteries from surface chemical, electrochemical and material science perspectives. PMID:27297565

  19. Time differential perturbed angular correlation (TDPAC) studies of the 133Ba ion uptake in bone crystals.

    PubMed

    Rimbert, J N; Kellershohn, C; Dumas, F; Hubert, C

    1981-03-01

    TDPAC measurements of the 356-81 keV gamma-ray cascade resulting from electron capture decay of 133Ba have been performed at room temperature on BaCl2 (aqueous solution and polycrystalline powder), and on samples where the 133Ba nucleus is bound to bone powder, and also to synthesised hydroxylapatite, all after absorption in vitro. As expected, the angular correlation is not perturbed in the solution. However, in the polycrystalline chloride the time dependence of the anisotropy of the cascade of 133Cs nuclide indicates that the decaying nucleus undergoes electric interactions due to different electric field gradients acting at the site of the nucleus. In 133Ba-bone powder the results show a static quadrupolar interaction differing with the absorption contact time during sample preparation, indicating that depth of 133Ba ion fixation in the bone crystal is dependent on this contact time. These results seem to be confirmed by the TDPAC measurements performed on 133Ba-hydroxylapatite samples where the contact times for absorption of active-ion 133Ba and hydroxylapatite in suspension were very different. PMID:7220599

  20. Relation between ligand design and transition energy for the praseodymium ion in crystals.

    PubMed

    Zhou, Xianju; Tanner, Peter A

    2015-01-01

    Ten substituted benzoate complexes of Pr(3+) of the type [Pr(XC6H4COO)3(H2O)n(DMF)m]p·(DMF)q (X = OCH3, NO2, OH, F, Cl, NH2) have been synthesized, and for eight of these crystallographic data are available. The electronic absorption and emission spectra of the complexes have been recorded and interpreted at temperatures down to 10 K for transitions involving the (3)P0 and (1)D2 J-multiplet terms. Generally, the electron-withdrawing groups X in the benzoate moiety lead to higher (3)P0 energy than electron-donating groups. Empirical relations have been found between the energies of the (3)P0 and (1)D2(1) levels and the Hammett sigma constants for substituents and the unit cell volume per Pr(3+) ion. The latter relationship is indicative of a correlation between the electronic state energy and the ligand dipole polarizability. This has been confirmed by reference to literature data for the LaX3:Pr(3+) systems, so that the ligand dipole polarizability is a key factor in determining the nephelauxetic shifts of 4f(N) ions in crystals. PMID:25474732

  1. XRD investigation of the strain/stress state of ion-irradiated crystals

    NASA Astrophysics Data System (ADS)

    Debelle, Aurélien; Declémy, Alain

    2010-05-01

    In this work, it is demonstrated that XRD is a powerful technique for the study of ion-irradiated materials. For this purpose, XRD experiments have been performed under different configurations on a <1 0 0>-oriented yttria-stabilized zirconia single crystal implanted with 300 keV caesium-ions at 3 × 10 14 cm -2. Initially, it is demonstrated that the depth strain profile can be determined from the refinement of a symmetric θ-2 θ scan. Moreover, in order to explore the whole XRD data, a model that describes the strain/stress state of the damaged layer is proposed. This model takes into account the elastic response of the bulk material (substrate) underneath the irradiated layer. The measured elastic strain is then the sum of a free strain due to the formation of radiation-induced defects and of an additional strain arising from the substrate elastic reaction. Application of this model allowed the calculation of the different strain contributions and the stress experienced by the irradiated layer. It is shown that these parameters may reach large values (respectively 0.7% and -1.9 GPa) despite the low radiation damage level.

  2. Ion beam crystallization of InAs/GaAs(001) nanostructures

    NASA Astrophysics Data System (ADS)

    Chebotarev, S. N.; Pashchenko, A. S.; Williamson, A.; Lunin, L. S.; Irkha, V. A.; Gamidov, V. A.

    2015-07-01

    A technique for ion beam crystallization of InAs/GaAs(001) nanostructures with quantum dots is proposed. The GaAs and InAs sputtering yields in the energy range E Ar+ = 200-300 eV and argon beam incidence angle θ = 30° are refined. It is demonstrated that growth rates of up to 0.1 ML/s for InAs and 0.05 ML/s for GaAs can be attained. According to atomic force and electron microscopy, photoluminescence, and Raman scattering data, enhancement of beam current density from 5 to 15 μA/cm2 at energy E Ar+ = 200 eV and substrate temperature T = 480°C leads to an increase in the quantum dot lateral size from 15 to 25 nm and in surface anisotropy from 2 × 1010 to 9 × 1010 cm-2. Current density growth to 20 μA/cm2 at the same ion energy is accompanied by a sharp increase in the mean lateral size of quantum dots to 70 nm and a decrease in the density to 3 × 1010 cm-2.

  3. Doping of Ga2O3 bulk crystals and NWs by ion implantation

    NASA Astrophysics Data System (ADS)

    Lorenz, K.; Peres, M.; Felizardo, M.; Correia, J. G.; Alves, L. C.; Alves, E.; López, I.; Nogales, E.; Méndez, B.; Piqueras, J.; Barbosa, M. B.; Araújo, J. P.; Gonçalves, J. N.; Rodrigues, J.; Rino, L.; Monteiro, T.; Villora, E. G.; Shimamura, K.

    2014-03-01

    Ga2O3 bulk single crystals have been implanted with 300 keV Europium ions to fluences ranging from 1×1013 to 4×1015 at/cm2. The damage build-up and Eu-incorporation was assessed by Rutherford Backscattering Spectrometry in the channeling mode (RBS/C). RBS/C results suggest that implantation causes a mixture of defect clusters and extended defects such as dislocations. Amorphisation starts at the surface for fluences around 1×1015 at/cm2 and then proceeds to deeper regions of the sample with increasing fluence. Amorphous regions and defect clusters are efficiently removed during rapid thermal annealing at ~1100 °C however, Eu diffuses towards the surface. Nevertheless, Eu ions are optically activated and show cathodoluminescence at room temperature. Results in bulk samples are compared to those in Eu-implanted Ga2O3 nanowires and despite strong similarities in the structural properties differences were found in the optical activation. Furthermore, damage and dopant incorporation studies were performed using the Perturbed Angular Correlation technique, which allows probing the immediate lattice surroundings of an implanted radioactive probe at the atomic level.

  4. Incorporation of copper ions into crystals of T2 copper-depleted laccase from Botrytis aclada

    SciTech Connect

    Osipov, E. M.; Polyakov, K. M.; Tikhonova, T. V.; Kittl, R.; Dorovatovskii, P.V.; Shleev, S. V.; Popov, V. O.; Ludwig, R.

    2015-11-18

    The restoration of the native form of laccase from B. aclada from the type 2 copper-depleted form of the enzyme was investigated. Copper ions were found to be incorporated into the active site after soaking the depleted enzyme in a Cu{sup +}-containing solution. Laccases belong to the class of multicopper oxidases catalyzing the oxidation of phenols accompanied by the reduction of molecular oxygen to water without the formation of hydrogen peroxide. The activity of laccases depends on the number of Cu atoms per enzyme molecule. The structure of type 2 copper-depleted laccase from Botrytis aclada has been solved previously. With the aim of obtaining the structure of the native form of the enzyme, crystals of the depleted laccase were soaked in Cu{sup +}- and Cu{sup 2+}-containing solutions. Copper ions were found to be incorporated into the active site only when Cu{sup +} was used. A comparative analysis of the native and depleted forms of the enzymes was performed.

  5. Failure mechanisms of single-crystal silicon electrodes in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Shi, Feifei; Song, Zhichao; Ross, Philip N.; Somorjai, Gabor A.; Ritchie, Robert O.; Komvopoulos, Kyriakos

    2016-06-01

    Long-term durability is a major obstacle limiting the widespread use of lithium-ion batteries in heavy-duty applications and others demanding extended lifetime. As one of the root causes of the degradation of battery performance, the electrode failure mechanisms are still unknown. In this paper, we reveal the fundamental fracture mechanisms of single-crystal silicon electrodes over extended lithiation/delithiation cycles, using electrochemical testing, microstructure characterization, fracture mechanics and finite element analysis. Anisotropic lithium invasion causes crack initiation perpendicular to the electrode surface, followed by growth through the electrode thickness. The low fracture energy of the lithiated/unlithiated silicon interface provides a weak microstructural path for crack deflection, accounting for the crack patterns and delamination observed after repeated cycling. On the basis of this physical understanding, we demonstrate how electrolyte additives can heal electrode cracks and provide strategies to enhance the fracture resistance in future lithium-ion batteries from surface chemical, electrochemical and material science perspectives.

  6. Failure mechanisms of single-crystal silicon electrodes in lithium-ion batteries.

    PubMed

    Shi, Feifei; Song, Zhichao; Ross, Philip N; Somorjai, Gabor A; Ritchie, Robert O; Komvopoulos, Kyriakos

    2016-01-01

    Long-term durability is a major obstacle limiting the widespread use of lithium-ion batteries in heavy-duty applications and others demanding extended lifetime. As one of the root causes of the degradation of battery performance, the electrode failure mechanisms are still unknown. In this paper, we reveal the fundamental fracture mechanisms of single-crystal silicon electrodes over extended lithiation/delithiation cycles, using electrochemical testing, microstructure characterization, fracture mechanics and finite element analysis. Anisotropic lithium invasion causes crack initiation perpendicular to the electrode surface, followed by growth through the electrode thickness. The low fracture energy of the lithiated/unlithiated silicon interface provides a weak microstructural path for crack deflection, accounting for the crack patterns and delamination observed after repeated cycling. On the basis of this physical understanding, we demonstrate how electrolyte additives can heal electrode cracks and provide strategies to enhance the fracture resistance in future lithium-ion batteries from surface chemical, electrochemical and material science perspectives. PMID:27297565

  7. Crystallization of ion-beam-synthesized SiC layer by thermal annealing

    NASA Astrophysics Data System (ADS)

    Wu, W.; Chen, D. H.; Cheung, W. Y.; Xu, J. B.; Wong, S. P.; Kwok, R. W. M.; Wilson, I. H.

    Synthesis of β-phase silicon carbide (SiC) layers has been achieved by high-dose carbon ion beam implantation into (100) silicon wafers with two different ion implantation energies, 40 keV and 65 keV. Subsequent furnace annealing was carried out in N2 at temperatures ranging from 600 to 1200 °C for 2 h. Rutherford backscattering spectrometry (RBS) analysis revealed carbon distribution and the formation of an SiC layer. Infrared spectroscopy (IR) exhibited a sharp absorption peak produced by the Si-C bond at 795 cm-1 with full width at half maximum (FWHM) of about 35 cm-1. A layer of crystalline SiC was formed after annealing the as-implanted sample at 1000 °C for 2 h. The influence of annealing temperature on the surface morphology and the dynamics of the crystallization procedure was studied by atomic force microscopy (AFM). A study of grain size and roughness revealed that the morphology of the SiC layer was largely dependent on annealing temperature, and the average grain size increased as the annealing temperature was raised. At about 900 °C, a layer of nanocrystalline SiC was formed on the sample surface, containing columnar grains with a FWHM of tens of nanometers and a height of less than ten nanometers.

  8. Optical absorption and thermoluminescence of MgAl 2O 4 spinel crystals implanted with Xe ++ ions

    NASA Astrophysics Data System (ADS)

    Afanasyev-Charkin, I. V.; Gritsyna, V. T.; Cooke, D. W.; Bennett, B. L.; Evans, C. R.; Hollander, M. G.; Sickafus, K. E.

    1999-01-01

    We have studied changes in optical absorption of MgAl 2O 4 spinel crystals implanted with 340 keV Xe ++ ions at about 120 K, to fluences ranging from 10 15-10 21 ions/m 2. With increasing ion fluence, we observe an increase in optical absorption, especially in the vicinity of two absorption bands: one centered at 5.3 eV, the other at 6.9 eV. The absorption band at 5.3 eV, caused by F-centers, saturates at a fluence between 1·10 18 and 1·10 19 ions/m 2. This is the same dose range in which formation of a metastable phase of spinel has been reported previously. The band at 6.9 eV grows with increasing dose and saturates at 1·10 20-3·10 20 ions/m 2. Previous studies have shown that spinel is amorphized by Xe ion irradiation in this dose range. Annealing studies were also conducted on the Xe ion implanted spinel crystals. By optical absorption, F-centers were found to anneal at 500°C. Thermoluminescence measurements revealed a temperature dependence of luminescence that correlates well with the optical absorption.

  9. Ranges of Channelled keV B Ions in Si Crystals with Impact Parameter Dependent Stopping Power

    NASA Astrophysics Data System (ADS)

    Kabadayi, Önder

    In this study we calculated channelled ion ranges of boron ions by using an impact parameter dependent stopping power model. Impact parameter dependent stopping powers for boron ions penetrating into Si <100> are investigated first for energies from 10 to 150 keV. We assumed that impact parameter dependent stopping powers can be expressed by a modified Oen-Robinson formula [1] (Oen et al. Nucl. Instr. Meth. B132, 647 (1976)). The model is implemented by developing a computer code to solve a differential equation numerically for which mean ion ranges can be obtained. The results are compared with experimental data as well as Crystal-TRIM, SRIM and similar procedures calculating ion ranges in solids. We have found an agreement between our results and literature.

  10. Low-temperature absorption and resonance Raman spectra of the MnO-4 ion doped in a KClO4 crystal

    NASA Astrophysics Data System (ADS)

    Leuchs, M.; Kiefer, W.

    1993-12-01

    We have performed polarized absorption and resonance Raman experiments on a permanganate ion doped in a potassium perchlorate single crystal at temperature T=15 K. At this low temperature the m(Cs) site splitting of the excited degenerate 1T2 electronic level of the permanganate ion is well resolved and the amount of splitting is about 40 cm-1. Due to the electronic configuration, one would expect that non-Condon terms have to be considered in the description of the absorption spectrum. For the theoretical simulation of our experimental results we have used expressions derived from the time-correlator formulation for the optical absorption. These are much easier to handle and they cause significant shorter calculation times than the usual sum-over-states expressions. In order to determine the symmetries and the wave-number positions of the site-split permanganate vibrations, we have performed resonance Raman experiments. The results obtained from these experiments form the basis for the interpretation of the absorption spectrum. The applied model includes the linear and quadratic electron-phonon and linear non-Condon coupling. Within this model we describe the multimode system and we show how a normal vibration, which apparently has no significant effects in the absorption spectrum, influences the discussion of the model system. For the fully symmetric breathing mode of the permanganate ion, we have calculated the change of the Mn-O equilibrium bond length in the electronic excited state from the corresponding linear electron-phonon coupling constant to be 4.6+/-0.4 pm.

  11. The EPR study of Mn2+ ion doped DADT single crystal produced under high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Ceylan, Ümit; Tapramaz, Recep

    2016-01-01

    An EPR study on Cu2+ and VO2+ doped di ammonium D-tartrate single crystals has been reported in previous papers, but the same host did not accept Mn2+ ion at the same reaction conditions in previous trials. In this study EPR study of Mn2+ ion doped di ammonium D tartrate single crystal, (DADT) [(NH4)2C4H4O6], produced in a reactor under high pressure and high temperature. The electronic transitions were determined by the optical absorption spectrum. Hyperfine splitting and g values of the Mn2+ ion forming a complex in the lattice were measured from experimental spectra and spin-spin dipolar splitting parameters D and E were found by the spectrum simulation techniques.

  12. Separation of Contributions from the Ion Core and Free Charge Carriers to the Magnetic Susceptibility of an Anisotropic Semiconductor Bi2Te3-Sb2Te3 Crystal

    NASA Astrophysics Data System (ADS)

    Stepanov, N. P.; Nalivkin, V. Yu.

    2016-05-01

    A technique is presented, by which the magnetic susceptibility χ | G of the ion core of an anisotropic semiconductor Bi2Te3-Sb2Te3 crystal is determined from experimental data on the magnetic susceptibility χ ∥ and χ ⊥ obtained with allowance for the orientation of the magnetic field vector H with respect to the trigonal C3 axis of the crystal in accordance with the expression χ ∥/ χ ⊥ = ( χ ∥ eh + χ G )/( χ ⊥ eh + χ G ).In this expression, the value of the magnetic susceptibility of free charge carriers χ ∥ eh and χ ⊥ eh depending on their effective masses m ∥ * and m ⊥ * known from the experiment is calculated within the framework of the Pauli and Landau- Peierls approaches. The found value of χ | G for Bi2Te3-Sb2Te3 crystals is in good agreement with experimental data, as well as with the estimates obtained in the framework of the Larmor approach explaining, in particular, a linear dependence of the molar magnetic susceptibility on the number of electrons in the molecule observed for a large number of compounds. The proposed technique can be extended to other anisotropic semiconductors.

  13. Separation of Contributions from the Ion Core and Free Charge Carriers to the Magnetic Susceptibility of an Anisotropic Semiconductor Bi2Te3-Sb2Te3 Crystal

    NASA Astrophysics Data System (ADS)

    Stepanov, N. P.; Nalivkin, V. Yu.

    2016-05-01

    A technique is presented, by which the magnetic susceptibility χ {|/ G } of the ion core of an anisotropic semiconductor Bi2Te3-Sb2Te3 crystal is determined from experimental data on the magnetic susceptibility χ ∥ and χ ⊥ obtained with allowance for the orientation of the magnetic field vector H with respect to the trigonal C3 axis of the crystal in accordance with the expression χ ∥/χ ⊥ = (χ {∥/ eh } + χ G )/(χ {⊥/ eh } + χ G ).In this expression, the value of the magnetic susceptibility of free charge carriers χ {∥/ eh } and χ {⊥/ eh } depending on their effective masses m {∥/*} and m {⊥/*} known from the experiment is calculated within the framework of the Pauli and Landau- Peierls approaches. The found value of χ {|/ G }for Bi2Te3-Sb2Te3 crystals is in good agreement with experimental data, as well as with the estimates obtained in the framework of the Larmor approach explaining, in particular, a linear dependence of the molar magnetic susceptibility on the number of electrons in the molecule observed for a large number of compounds. The proposed technique can be extended to other anisotropic semiconductors.

  14. Propagation of ion-acoustic solitons in an electron beam-superthermal plasma system with finite ion-temperature: Linear and fully nonlinear investigation

    SciTech Connect

    Saberian, E.; Esfandyari-Kalejahi, A.; Rastkar-Ebrahimzadeh, A.; Afsari-Ghazi, M.

    2013-03-15

    The propagation of ion-acoustic (IA) solitons is studied in a plasma system, comprised of warm ions and superthermal (Kappa distributed) electrons in the presence of an electron-beam by using a hydrodynamic model. In the linear analysis, it is seen that increasing the superthermality lowers the phase speed of the IA waves. On the other hand, in a fully nonlinear investigation, the Mach number range and characteristics of IA solitons are analyzed, parametrically and numerically. It is found that the accessible region for the existence of IA solitons reduces with increasing the superthermality. However, IA solitons with both negative and positive polarities can coexist in the system. Additionally, solitary waves with both subsonic and supersonic speeds are predicted in the plasma, depending on the value of ion-temperature and the superthermality of electrons in the system. It is examined that there are upper critical values for beam parameters (i.e., density and velocity) after which, IA solitary waves could not propagate in the plasma. Furthermore, a typical interaction between IA waves and the electron-beam in the plasma is confirmed.

  15. An investigation of the angular distributions of fragment ions arising from the linear CS2 and CO2 molecules

    NASA Astrophysics Data System (ADS)

    Graham, P.; Ledingham, K. W. D.; Singhal, R. P.; McCanny, T.; Hankin, S. M.; Fang, X.; Smith, D. J.; Kosmidis, C.; Tzallas, P.; Langley, A. J.; Taday, P. F.

    1999-12-01

    The nonlinear interaction of the triatomic molecules CS2 and CO2 with the intense field of a linearly polarized laser beam of femtosecond (fs) pulse duration, was used to study the ionization and dissociation of the parent molecule. The fragment ion angular distributions arising from the Coulomb explosion of the parent ions were also measured. For CS2, the angular distributions of CS2+, CS22+, CS23+, CS+, CS2+, Sn+ (nicons/Journals/Common/le" ALT="le" ALIGN="TOP"/>6) and Cm+ (micons/Journals/Common/le" ALT="le" ALIGN="TOP"/>4) ions are presented for a laser intensity of 1 × 1016 W cm-2 at a wavelength of 790 nm and pulse duration of 50 fs. The angular distributions of the parent molecular ions are all isotropic. The Sn+ fragments are peaked along the time-of-flight (TOF) axis, whereas the Cm+ fragments explode perpendicularly to this. Similar results for CO2 are also presented for comparison. The S ion distributions do not narrow as their ionic charge increases, and it is argued that the angular distributions for CS2 are due mainly to the angular dependence of the ionization probability. On the other hand, the distributions from the lighter CO2 molecule are thought to be at least partly due to alignment via dipole moments induced by the laser, as in this case the On+ angular distributions are seen to narrow as their charge increases. The conclusion of these results is that the laser pulse may be too short for the CS2 molecule to align in the pulse. Angular distributions are also presented for varying laser pulse durations, in the range of 50 fs to 300 ps. The dynamics of the ionization/dissociation mechanism are discussed in the context of the TOF mass spectra and angular distributions recorded for CS2.

  16. 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.

  17. Engineering study of a 10 MeV heavy ion linear accelerator

    SciTech Connect

    Fong, C.G.; Fessenden, T.J.; Fulton, R.L.; Keefe, D.

    1989-03-01

    LBL's Heavy Ion Fusion Accelerator Research group has completed the engineering study of the Induction Linac Systems Experiment (ILSE). ILSE will address nearly all accelerator physics issues of a scaled heavy ion induction linac inertial fusion pellet driver. Designed as a series of subsystem experiments, ILSE will accelerate 16 parallel carbon ion beams from a 2 MeV injector presently under development to 10 MeV at one ..mu..sec. This overview paper will present the physics and engineering requirements and describe conceptual design approaches for building ILSE. Major ILSE subsystems consist of electrostatic focusing quadrupole matching and accelerating sections, a 16 to 4 beam transverse combining section, a 4 beam magnetic focusing quadrupole accelerating section, a single beam 180 degree bend section, a drift compression section and a final focus and target chamber. These subsystems are the subject of accompanying papers. Also discussed are vacuum and alignment, diagnostics/data acquisition and controls, key conclusions and plans for further development. 10 refs., 4 figs., 1 tab.

  18. Full characterization of laser-accelerated ion beams using Faraday cup, silicon carbide, and single-crystal diamond detectors

    SciTech Connect

    Margarone, D.; Prokupek, J.; Rus, B.; Krasa, J.; Velyhan, A.; Laska, L.; Giuffrida, L.; Torrisi, L.; Picciotto, A.; Nowak, T.; Musumeci, P.; Mocek, T.; Ullschmied, J.

    2011-05-15

    Multi-MeV beams of light ions have been produced using the 300 picosecond, kJ-class iodine laser, operating at the Prague Asterix Laser System facility in Prague. Real-time ion diagnostics have been performed by the use of various time-of-flight (TOF) detectors: ion collectors (ICs) with and without absorber thin films, new prototypes of single-crystal diamond and silicon carbide detectors, and an electrostatic ion mass spectrometer (IEA). In order to suppress the long photopeak induced by soft X-rays and to avoid the overlap with the signal from ultrafast particles, the ICs have been shielded with Al foil filters. The application of large-bandgap semiconductor detectors (>3 eV) ensured cutting of the plasma-emitted visible and soft-UV radiation and enhancing the sensitivity to the very fast proton/ion beams. Employing the IEA spectrometer, various ion species and charge states in the expanding laser-plasma have been determined. Processing of the experimental data based on the TOF technique, including estimation of the plasma fast proton maximum and peak energy, ion beam currents and total charge, total number of fast protons, as well as deconvolution processes, ion stopping power, and ion/photon transmission calculations for the different metallic filters used, are reported.

  19. Revelation of endogenously bound Fe{sup 2+} ions in the crystal structure of ferritin from Escherichia coli

    SciTech Connect

    Thiruselvam, Viswanathan; Sivaraman, Padavattan; Kumarevel, Thirumananseri; Ponnuswamy, Mondikalipudur Nanjappagounder

    2014-10-24

    Highlights: • Crystal structure of ferritin was determined. • Endogenously expressed iron’s were identified. • Binuclear iron sites were observed at A and B active sites. - Abstract: Ferritin is an iron regulatory protein. It is responsible for storage and detoxification of excess iron thereby it regulates iron level in the body. Here we report the crystal structure of ferritin with two endogenously expressed Fe atoms binding in both the sites. The protein was purified and characterized by MALDI-TOF and N-terminal amino acid sequencing. The crystal belongs to I4 space group and it diffracted up to 2.5 Å. The structural analysis suggested that it crystallizes as hexamer and confirmed that it happened to be the first report of endogenously expressed Fe ions incorporated in both the A and B sites, situated in between the helices.

  20. Highly stable linear carbonate-containing electrolytes with fluoroethylene carbonate for high-performance cathodes in sodium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Yongwon; Lee, Jaegi; Kim, Hyungsub; Kang, Kisuk; Choi, Nam-Soon

    2016-07-01

    Employing linear carbonates such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as electrolyte solvents provides an opportunity to design appropriate electrolyte systems for high-performance sodium-ion batteries (SIBs). However, in practice, the use of linear carbonate-containing electrolytes is quite challenging because linear carbonates readily decompose at Na metal electrodes or sodiated anodes. One of the promising approaches is using an electrolyte additive to resolve the critical problems related to linear carbonates. Our investigation reveals that remarkable enhancement in electrochemical performance of Na4Fe3(PO4)2(P2O7) cathodes with linear carbonate-containing electrolytes is achieved by using a fluoroethylene carbonate (FEC) additive. Importantly, the initial Coulombic efficiency of the Na deposition/stripping on a stainless steel (SS) electrode is drastically improved from 16% to 90% by introducing the FEC additive into ethylene carbonate (EC)/propylene carbonate (PC)/DEC (5/3/2, v/v/v)/0.5 M NaClO4. The underlying mechanism of FEC at the electrode-electrolyte interface is clearly demonstrated by 13C nuclear magnetic resonance (NMR). In addition, the Na4Fe3(PO4)2(P2O7) cathode in EC/PC/DEC (5/3/2, v/v/v)/0.5 M sodium perchlorate (NaClO4) with FEC delivers a discharge capacity of 90.5 mAh g-1 at a current rate of C/2 and exhibits excellent capacity retention of 97.5% with high Coulombic efficiency of 99.6% after 300 cycles at 30 °C.

  1. Acoustic waveguiding by pliable conduits with axial cross sections as linear waveguides in two-dimensional sonic crystals.

    PubMed

    Cicek, Ahmet; Kaya, Olgun Adem; Ulug, Bulent

    2013-11-01

    Pliable conduits composed of periodically arranged concentric aluminum tori in air, with their axial cross sections acting as linear waveguides in two-dimensional sonic crystals, are numerically shown to guide acoustic waves in three dimensions in a flexible manner. Waveguide band structures are obtained by exploiting axial symmetry in a super-cell approach through two-dimensional finite-element simulations under the periodic boundary conditions. One isolated band having a bandwidth of 19.66% or 10.10% is observed for each guide, whose cross section is either in square or triangular geometry, respectively. Corresponding mode profiles indicate efficient guiding, as the acoustic energy is mainly concentrated in the hollow-core region of the guides. Transmittance spectra calculated through finite-element simulations are in agreement with the computed guiding bands. Transmittance along the waveguides with square and triangular axial cross sections around mid-band frequencies of their guiding bands varies slightly from -6.05 and -6.65 dB to -5.98 and -8.86 dB, respectively, as the guide length is increased from 10 to 200 periods. Efficient guiding across the smooth bends over circular arcs up to 90 deg is also demonstrated through three-dimensional finite-element method simulations. PMID:24180772

  2. Range and Annealing Behaviour of Pb+ Ions Implanted into LiNbO3 Crystals at Moderate Energies

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Hu, Hui; Zhang, Jian-Hua; Liu, Xiang-Dong; Xia, Hui-Hao; Shi, Bo-Rong; Wang, Ke-Ming

    2002-01-01

    Pb+ ions have been implanted into LiNbO3 crystals in the energy range of 100-350 keV at doses of 5×1015, 1×1016 and 2×1016 ions/cm2. The profile of the implanted ions was measured by Rutherford backscattering. The mean projected range and the range straggling obtained from the experiment were compared with the TRIM'98 and SRIM 2000 code. In the present case, the TRIM'98 code predicts experimental values better than those of the SRIM 2000 code. The depth distribution is also found to be independent of dose for 350 keV Pb+ implanted into LiNbO3 crystals. After 800°C annealing for 60 min in ambient air, obvious diffusion occurs to the implanted Pb+ ions at 150 keV with a dose of 5×1015 ions/cm2. After a low-temperature treatment at 77 K in liquid nitrogen, no obvious diffusion phenomenon occurs for the implanted Pb+ ions in LiNbO3.

  3. Lithium ions in the van der Waals gap of Bi{sub 2}Se{sub 3} single crystals

    SciTech Connect

    Bludska, J.; Jakubec, I.; Karamazov, S.; Horak, J.; Uher, C.

    2010-12-15

    Insertion/extraction of lithium ions into/from Bi{sub 2}Se{sub 3} crystals was investigated by means of cyclic voltammetry. The process of insertion is reflected in the appearance of two bands on voltammograms at {approx}1.7 and {approx}1.5 V, corresponding to the insertion of Li{sup +} ions into octahedral and tetrahedral sites of the van der Waals gap of these layered crystals. The process of extraction of Li{sup +} ions from the gap results in the appearance of four bands on the voltammograms. The bands 1 and 2 at {approx}2.1 and {approx}2.3 V correspond to the extraction of a part of Li{sup +} guest ions from the octahedral and tetrahedrals sites and this extraction has a character of a reversible intercalation/deintercalation process. A part of Li{sup +} ions is bound firmly in the crystal due to the formation of negatively charged clusters of the (LiBiSe{sub 2}.Bi{sub 3}Se{sub 4}{sup -}) type. A further extraction of Li{sup +} ions from the van der Waals gap is associated with the presence of bands 3 and 4 placed at {approx}2.5 and {approx}2.7 V on the voltammograms as their extraction needs higher voltage due to the influence of negative charges localized on these clusters. -- Graphical abstract: Insertion/extraction of lithium ions into/from Bi{sub 2}Se{sub 3} layered crystals was investigated by cyclic voltammetry. The extraction of Li{sup +} results in the appearance of four bands on the voltammograms. The first two bands have a character of a reversible process. A part of Li{sup +} ions is bound firmly in the crystal due to the formation of negatively charged clusters of the (LiBiSe{sub 2}.Bi{sub 3}Se{sub 4}{sup -}) type. Their extraction needs higher voltage due to the negative charge. Display Omitted

  4. Interplay of energy dissipation, ion-induced mixing, and crystal structure recovery, and surface effects in ion-irradiated magnetic Fe/Cr/Fe trilayers

    SciTech Connect

    Brodyanski, A.; Bock, W.; Kopnarski, M.; Reuscher, B.; Blomeier, S.; Hillebrands, B.; Gnaser, H.

    2011-12-01

    The influence of the ion irradiation by 30 keV Ga{sup +} ions on the crystal structure, chemical ordering, magnetic properties, and topography of epitaxial Fe/Cr/Fe trilayers was investigated by different analytical techniques. We present direct experimental evidence, supported by theoretical estimates, that two processes take place concurrently due to the Ga-ion implantation. (i) A complete atom mixing of the Cr atoms within the Fe multilayers is occurring due to the collision cascades during the ballistic regime, and (ii) an essentially complete recovery of the initial single-crystal quality of the Fe multilayers by healing the melted and damaged area through the thermal spike phase occurs. Based on the experimental range distributions and theoretical modeling, channeling of Ga{sup +} ions in the experiments is found to contribute weakly to ion penetration and stopping, and the relative fraction of the well-channeled ions is marginally small. On the other hand, this weak channeling is sufficient to reduce the sputter yield by a factor of more than 5 in comparison with the sputtering of polycrystalline samples, evidence for the fact that the magnitude of channeling is not of primary importance for the sputtering. We offer an explanation for the observation of dramatic and abrupt changes in the surface roughness with increasing fluences in terms of a transformation from a single-phase single-crystal implanted region (bcc-Fe) to a mixture of the polycrystalline {alpha}-Fe-like bcc and {alpha}-Fe{sub 3}Ga structures within the outer half of the original Fe/Cr/Fe trilayer at fluences above 6.25 x 10{sup 16} ion/cm{sup 2}. The wall-like elevations appearing at the boundary of the irradiated areas were analyzed experimentally by varying the irradiation conditions. We showed that the wall size is governed by the ion-current density applied. A physical explanation for the appearance of such topographic features is presented, which would be valid for any material

  5. Interplay of energy dissipation, ion-induced mixing, and crystal structure recovery, and surface effects in ion-irradiated magnetic Fe/Cr/Fe trilayers

    NASA Astrophysics Data System (ADS)

    Brodyanski, A.; Blomeier, S.; Gnaser, H.; Bock, W.; Hillebrands, B.; Kopnarski, M.; Reuscher, B.

    2011-12-01

    The influence of the ion irradiation by 30 keV Ga+ ions on the crystal structure, chemical ordering, magnetic properties, and topography of epitaxial Fe/Cr/Fe trilayers was investigated by different analytical techniques. We present direct experimental evidence, supported by theoretical estimates, that two processes take place concurrently due to the Ga-ion implantation. (i) A complete atom mixing of the Cr atoms within the Fe multilayers is occurring due to the collision cascades during the ballistic regime, and (ii) an essentially complete recovery of the initial single-crystal quality of the Fe multilayers by healing the melted and damaged area through the thermal spike phase occurs. Based on the experimental range distributions and theoretical modeling, channeling of Ga+ ions in the experiments is found to contribute weakly to ion penetration and stopping, and the relative fraction of the well-channeled ions is marginally small. On the other hand, this weak channeling is sufficient to reduce the sputter yield by a factor of more than 5 in comparison with the sputtering of polycrystalline samples, evidence for the fact that the magnitude of channeling is not of primary importance for the sputtering. We offer an explanation for the observation of dramatic and abrupt changes in the surface roughness with increasing fluences in terms of a transformation from a single-phase single-crystal implanted region (bcc-Fe) to a mixture of the polycrystalline α-Fe-like bcc and α-Fe3Ga structures within the outer half of the original Fe/Cr/Fe trilayer at fluences above 6.25 × 1016 ion/cm2. The wall-like elevations appearing at the boundary of the irradiated areas were analyzed experimentally by varying the irradiation conditions. We showed that the wall size is governed by the ion-current density applied. A physical explanation for the appearance of such topographic features is presented, which would be valid for any material irradiated by a focused ion beam.

  6. A Generic Multiple Reaction Monitoring Based Approach for Plant Flavonoids Profiling Using a Triple Quadrupole Linear Ion Trap Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Yan, Zhixiang; Lin, Ge; Ye, Yang; Wang, Yitao; Yan, Ru

    2014-06-01

    Flavonoids are one of the largest classes of plant secondary metabolites serving a variety of functions in plants and associating with a number of health benefits for humans. Typically, they are co-identified with many other secondary metabolites using untargeted metabolomics. The limited data quality of untargeted workflow calls for a shift from the breadth-first to the depth-first screening strategy when a specific biosynthetic pathway is focused on. Here we introduce a generic multiple reaction monitoring (MRM)-based approach for flavonoids profiling in plants using a hybrid triple quadrupole linear ion trap (QTrap) mass spectrometer. The approach includes four steps: (1) preliminary profiling of major aglycones by multiple ion monitoring triggered enhanced product ion scan (MIM-EPI); (2) glycones profiling by precursor ion triggered EPI scan (PI-EPI) of major aglycones; (3) comprehensive aglycones profiling by combining MIM-EPI and neutral loss triggered EPI scan (NL-EPI) of major glycone; (4) in-depth flavonoids profiling by MRM-EPI with elaborated MRM transitions. Particularly, incorporation of the NH3 loss and sugar elimination proved to be very informative and confirmative for flavonoids screening. This approach was applied for profiling flavonoids in Astragali radix ( Huangqi), a famous herb widely used for medicinal and nutritional purposes in China. In total, 421 flavonoids were tentatively characterized, among which less than 40 have been previously reported in this medicinal plant. This MRM-based approach provides versatility and sensitivity that required for flavonoids profiling in plants and serves as a useful tool for plant metabolomics.

  7. A Novel Dual-Pressure Linear Ion Trap Mass Spectrometer Improves the Analysis of Complex Protein Mixtures

    PubMed Central

    Pekar, Tonya; Blethrow, Justin D.; Schwartz, Jae C.; Merrihew, Gennifer E.; MacCoss, Michael J.; Swaney, Danielle L.; Russell, Jason D.; Coon, Joshua J.; Zabrouskov, Vlad

    2009-01-01

    The considerable progress in high throughput proteomics analysis via liquid chromatography-electrospray ionization-tandem mass spectrometry over the last decade has been fueled to a large degree by continuous improvements in instrumentation. High throughput identification experiments are based on peptide sequencing and are largely accomplished through the use of tandem mass spectrometry, with ion trap and trap-based instruments having become broadly adopted analytical platforms. To satisfy increasingly demanding requirements for depth of characterization and throughput, we present a newly developed dual-pressure linear ion trap mass spectrometer (LTQ Velos) that features increased sensitivity, afforded by a new source design, and demonstrates practical cycle times two times shorter than that of an LTQ XL, while improving or maintaining spectral quality for MS/MS fragmentation spectra. These improvements resulted in a substantial increase in the detection and identification of both proteins and unique peptides from the complex proteome of Caenorhabditis elegans, as compared to existing platforms. The greatly increased ion flux into the mass spectrometer in combination with improved isolation of low-abundance precursor ions resulted in increased detection of low-abundance peptides. These improvements cumulatively resulted in a substantially greater penetration into the baker’s yeast (Saccharomyces cerevisiae) proteome compared to LTQ XL. Alternatively, faster cycle times on the new instrument allowed for higher throughput for a given depth of proteome analysis, with more peptides and proteins identified in 60 min using an LTQ Velos than in 180 min using an LTQ XL. When mass analysis was carried out with resolution in excess of 25,000 FWHM, it became possible to isotopically resolve a small intact protein and its fragments, opening possibilities for top down experiments. PMID:19689114

  8. Linear Energy Transfer-Dependent Change in Rice Gene Expression Profile after Heavy-Ion Beam Irradiation.

    PubMed

    Ishii, Kotaro; Kazama, Yusuke; Morita, Ryouhei; Hirano, Tomonari; Ikeda, Tokihiro; Usuda, Sachiko; Hayashi, Yoriko; Ohbu, Sumie; Motoyama, Ritsuko; Nagamura, Yoshiaki; Abe, Tomoko

    2016-01-01

    A heavy-ion beam has been recognized as an effective mutagen for plant breeding and applied to the many kinds of crops including rice. In contrast with X-ray or γ-ray, the heavy-ion beam is characterized by a high linear energy transfer (LET). LET is an important factor affecting several aspects of the irradiation effect, e.g. cell survival and mutation frequency, making the heavy-ion beam an effective mutagen. To study the mechanisms behind LET-dependent effects, expression profiling was performed after heavy-ion beam irradiation of imbibed rice seeds. Array-based experiments at three time points (0.5, 1, 2 h after the irradiation) revealed that the number of up- or down-regulated genes was highest 2 h after irradiation. Array-based experiments with four different LETs at 2 h after irradiation identified LET-independent regulated genes that were up/down-regulated regardless of the value of LET; LET-dependent regulated genes, whose expression level increased with the rise of LET value, were also identified. Gene ontology (GO) analysis of LET-independent up-regulated genes showed that some GO terms were commonly enriched, both 2 hours and 3 weeks after irradiation. GO terms enriched in LET-dependent regulated genes implied that some factor regulates genes that have kinase activity or DNA-binding activity in cooperation with the ATM gene. Of the LET-dependent up-regulated genes, OsPARP3 and OsPCNA were identified, which are involved in DNA repair pathways. This indicates that the Ku-independent alternative non-homologous end-joining pathway may contribute to repairing complex DNA legions induced by high-LET irradiation. These findings may clarify various LET-dependent responses in rice. PMID:27462908

  9. Linear Energy Transfer-Dependent Change in Rice Gene Expression Profile after Heavy-Ion Beam Irradiation

    PubMed Central

    Ishii, Kotaro; Kazama, Yusuke; Morita, Ryouhei; Hirano, Tomonari; Ikeda, Tokihiro; Usuda, Sachiko; Hayashi, Yoriko; Ohbu, Sumie; Motoyama, Ritsuko; Nagamura, Yoshiaki; Abe, Tomoko

    2016-01-01

    A heavy-ion beam has been recognized as an effective mutagen for plant breeding and applied to the many kinds of crops including rice. In contrast with X-ray or γ-ray, the heavy-ion beam is characterized by a high linear energy transfer (LET). LET is an important factor affecting several aspects of the irradiation effect, e.g. cell survival and mutation frequency, making the heavy-ion beam an effective mutagen. To study the mechanisms behind LET-dependent effects, expression profiling was performed after heavy-ion beam irradiation of imbibed rice seeds. Array-based experiments at three time points (0.5, 1, 2 h after the irradiation) revealed that the number of up- or down-regulated genes was highest 2 h after irradiation. Array-based experiments with four different LETs at 2 h after irradiation identified LET-independent regulated genes that were up/down-regulated regardless of the value of LET; LET–dependent regulated genes, whose expression level increased with the rise of LET value, were also identified. Gene ontology (GO) analysis of LET-independent up-regulated genes showed that some GO terms were commonly enriched, both 2 hours and 3 weeks after irradiation. GO terms enriched in LET-dependent regulated genes implied that some factor regulates genes that have kinase activity or DNA-binding activity in cooperation with the ATM gene. Of the LET-dependent up-regulated genes, OsPARP3 and OsPCNA were identified, which are involved in DNA repair pathways. This indicates that the Ku-independent alternative non-homologous end-joining pathway may contribute to repairing complex DNA legions induced by high-LET irradiation. These findings may clarify various LET-dependent responses in rice. PMID:27462908

  10. Origins of low resistivity in Al ion-implanted ZnO bulk single crystals

    SciTech Connect

    Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.; Kinomura, A.

    2011-06-15

    The origins of low resistivity in Al ion-implanted ZnO bulk single crystals are studied by combining Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), photoluminescence (PL), and Van der Pauw methods. The Al-ion implantation (peak concentration: 2.6 x 10{sup 20}cm{sup -3}) into ZnO is performed using a multiple-step energy. The resistivity decreases from {approx}10{sup 4{Omega}} cm for un-implanted ZnO to 1.4 x 10{sup -1{Omega}} cm for as-implanted, and reaches 6.0 x 10{sup -4{Omega}} cm for samples annealed at 1000 deg. C. RBS and NRA measurements for as-implanted ZnO suggest the existence of the lattice displacement of Zn (Zn{sub i}) and O (O{sub i}), respectively. After annealing at 1000 deg. C, the Zn{sub i} related defects remain and the O{sub i} related defects disappear. The origin of the low resistivity in the as-implanted sample is attributed to the Zn{sub i} ({approx}30 meV [Look et al., Phys. Rev. Lett. 82, 2552 (1999)]). In contrast, the origin of the low resistivity in the sample annealed at 1000 deg. C is assigned to both of the Zn{sub i} related defects and the electrically activated Al donor. A new PL emission appears at around 3.32 eV after annealing at 1000 deg. C, suggesting electrically activated Al donors.

  11. Comparison of kinetic and extended magnetohydrodynamics computational models for the linear ion temperature gradient instability in slab geometry

    SciTech Connect

    Schnack, D. D.; Cheng, J.; Parker, S. E.; Barnes, D. C.

    2013-06-15

    We perform linear stability studies of the ion temperature gradient (ITG) instability in unsheared slab geometry using kinetic and extended magnetohydrodynamics (MHD) models, in the regime k{sub ∥}/k{sub ⊥}≪1. The ITG is a parallel (to B) sound wave that may be destabilized by finite ion Larmor radius (FLR) effects in the presence of a gradient in the equilibrium ion temperature. The ITG is stable in both ideal and resistive MHD; for a given temperature scale length L{sub Ti0}, instability requires that either k{sub ⊥}ρ{sub i} or ρ{sub i}/L{sub Ti0} be sufficiently large. Kinetic models capture FLR effects to all orders in either parameter. In the extended MHD model, these effects are captured only to lowest order by means of the Braginskii ion gyro-viscous stress tensor and the ion diamagnetic heat flux. We present the linear electrostatic dispersion relations for the ITG for both kinetic Vlasov and extended MHD (two-fluid) models in the local approximation. In the low frequency fluid regime, these reduce to the same cubic equation for the complex eigenvalue ω=ω{sub r}+iγ. An explicit solution is derived for the growth rate and real frequency in this regime. These are found to depend on a single non-dimensional parameter. We also compute the eigenvalues and the eigenfunctions with the extended MHD code NIMROD, and a hybrid kinetic δf code that assumes six-dimensional Vlasov ions and isothermal fluid electrons, as functions of k{sub ⊥}ρ{sub i} and ρ{sub i}/L{sub Ti0} using a spatially dependent equilibrium. These solutions are compared with each other, and with the predictions of the local kinetic and fluid dispersion relations. Kinetic and fluid calculations agree well at and near the marginal stability point, but diverge as k{sub ⊥}ρ{sub i} or ρ{sub i}/L{sub Ti0} increases. There is good qualitative agreement between the models for the shape of the unstable global eigenfunction for L{sub Ti0}/ρ{sub i}=30 and 20. The results quantify how far

  12. Multi-color persistent luminescence in transparent glass ceramics containing spinel nano-crystals with Mn2+ ions

    NASA Astrophysics Data System (ADS)

    Zhuang, Yixi; Ueda, Jumpei; Tanabe, Setsuhisa

    2014-11-01

    Transparent inorganic materials showing persistent luminescence can act as cover layer and emergency lighting for security signs in the dark. Herein, we report a Mn2+-activated glass and transparent glass ceramics containing spinel-type Zn1+xGa2-2xGexO4 (0 ≤ x ≤ 1) nano-crystals, which show multi-color persistent luminescence for more than 10 min. The color of persistent luminescence showed a remarkable change from red, to orange, greenish, and green with respect to the increase of annealing temperature. The effect has been explained due to the variation of crystal field strength surrounding the Mn2+ ions.

  13. Characterization of high energy Xe ion irradiation effects in single crystal molybdenum with depth-resolved synchrotron microbeam diffraction

    NASA Astrophysics Data System (ADS)

    Yun, Di; Miao, Yinbin; Xu, Ruqing; Mei, Zhigang; Mo, Kun; Mohamed, Walid; Ye, Bei; Pellin, Michael J.; Yacout, Abdellatif M.

    2016-04-01

    Microbeam X-ray diffraction experiments were conducted at beam line 34-ID of the Advanced Photon Source (APS) on fission fragment energy Xe heavy ion irradiated single crystal Molybdenum (Mo). Lattice strain measurements were obtained with a depth resolution of 0.7 μm, which is critical in resolving the peculiar heterogeneity of irradiation damage associated with heavy ion irradiation. Q-space diffraction peak shift measurements were correlated with lattice strain induced by the ion irradiations. Transmission electron microscopy (TEM) characterizations were performed on the as-irradiated materials as well. Nanometer sized Xe bubble microstructures were observed via TEM. Molecular Dynamics (MD) simulations were performed to help interpret the lattice strain measurement results from the experiment. This study showed that the irradiation effects by fission fragment energy Xe ion irradiations can be collaboratively understood with the depth resolved X-ray diffraction and TEM measurements under the assistance of MD simulations.

  14. Polymeric ionic liquid-plastic crystal composite electrolytes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Li, Xiaowei; Zhang, Zhengxi; Li, Sijian; Yang, Li; Hirano, Shin-ichi

    2016-03-01

    In this work, composite polymer electrolytes (CPEs), that is, 80%[(1-x)PIL-(x)SN]-20%LiTFSI, are successfully prepared by using a pyrrolidinium-based polymeric ionic liquid (P(DADMA)TFSI) as a polymer host, succinonitrile (SN) as a plastic crystal, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as a lithium salt. XRD and DSC measurements confirm that the as-obtained CPEs have amorphous structures. The 80%[50%PIL-50%SN]-20%LiTFSI (50% SN) electrolyte reveals a high room temperature ionic conductivity of 5.74 × 10-4 S cm-1, a wide electrochemical window of 5.5 V, as well as good mechanical strength with a Young's modulus of 4.9 MPa. Li/LiFePO4 cells assembled with the 50% SN electrolyte at 0.1C rate can deliver a discharge capacity of about 150 mAh g-1 at 25 °C, with excellent capacity retention. Furthermore, such cells are able to achieve stable discharge capacities of 131.8 and 121.2 mAh g-1 at 0.5C and 1.0C rate, respectively. The impressive findings demonstrate that the electrolyte system prepared in this work has great potential for application in lithium ion batteries.

  15. Spectroscopy of single Pr3+ ion in LaF3 crystal at 1.5 K

    PubMed Central

    Nakamura, Ippei; Yoshihiro, Tatsuya; Inagawa, Hironori; Fujiyoshi, Satoru; Matsushita, Michio

    2014-01-01

    Optical read-out and manipulation of the nuclear spin state of single rare-earth ions doped in a crystal enable the large-scale storage and the transport of quantum information. Here, we report the photo-luminescence excitation spectroscopy results of single Pr3+ ions in a bulk crystal of LaF3 at 1.5 K. In a bulk sample, the signal from a single ion at the focus is often hidden under the background signal originating from numerous out-of-focus ions in the entire sample. To combine with a homemade cryogenic confocal microscope, we developed a reflecting objective that works in superfluid helium with a numerical aperture of 0.99, which increases the signal by increasing the solid angle of collection to 1.16π and reduces the background by decreasing the focal volume. The photo-luminescence excitation spectrum of single Pr3+ was measured at a wing of the spectral line of the 3H4 → 3P0 transition at 627.33 THz (477.89 nm). The spectrum of individual Pr3+ ions appears on top of the background of 60 cps as isolated peaks with intensities of 20–30 cps and full-width at half-maximum widths of approximately 3 MHz at an excitation intensity of 80 W cm−2. PMID:25482137

  16. Spectral studies on Ag 8+ ions irradiated LAHCl·H 2O and LAHBr·H 2O single crystals

    NASA Astrophysics Data System (ADS)

    Sangeetha, K.; Ramesh Babu, R.; Ramamurthi, K.; Prakash, Jai; Khan, S. A.

    2011-09-01

    L-Arginine hydrochloride monohydrate and L-arginine hydrobromide monohydrate single crystals are irradiated by 100 MeV Ag 8+ swift heavy ions. The residual gases liberated from the irradiated samples are monitored as a function of ion fluence using quadrupole mass analyzer. The C 2H 3+, C 2H 2, N 2, CO, HCl and CO 2 are the dominant gases liberated. Fourier transform infrared spectra of irradiated crystals explain the breaking of bonds in a localized region of the crystals. The crystallinity of irradiated crystals is analyzed by powder X-ray diffractions.

  17. Robust quantum gates and a bus architecture for quantum computing with rare-earth-ion-doped crystals

    SciTech Connect

    Wesenberg, Janus; Moelmer, Klaus

    2003-07-01

    We present a composite pulse controlled phase gate which, together with a bus architecture, improves the feasibility of a recent quantum computing proposal based on rare-earth-ion-doped crystals. The proposed gate operation is tolerant to variations between ions of coupling strengths, pulse lengths, and frequency shifts. In the absence of decoherence effects, it achieves worst case fidelities above 0.999 with relative variations in coupling strength as high as 10% and frequency shifts up to several percent of the resonant Rabi frequency of the laser used to implement the gate. We outline an experiment to demonstrate the creation and detection of maximally entangled states in the system.

  18. Rapid screening and characterization of drug metabolites using multiple ion monitoring dependent product ion scan and postacquisition data mining on a hybrid triple quadrupole-linear ion trap mass spectrometer.

    PubMed

    Yao, Ming; Ma, Li; Duchoslav, Eva; Zhu, Mingshe

    2009-06-01

    Multiple ion monitoring (MIM)-dependent acquisition with a triple quadrupole-linear ion trap mass spectrometer (Q-trap) was previously developed for drug metabolite profiling. In the analysis, multiple predicted metabolite ions are monitored in both Q1 and Q3 regardless of their fragmentations. The collision energy in Q2 is set to a low value to minimize fragmentation. Once an expected metabolite is detected by MIM, enhanced product ion (EPI) spectral acquisition of the metabolite is triggered. To analyze in vitro metabolites, MIM-EPI retains the sensitivity and selectivity similar to that of multiple reaction monitoring (MRM)-EPI in the analysis of in vitro metabolites. Here we present an improved approach utilizing MIM-EPI for data acquisition and multiple data mining techniques for detection of metabolite ions and recovery of their MS/MS spectra. The postacquisition data processing tools included extracted ion chromatographic analysis, product ion filtering and neutral loss filtering. The effectiveness of this approach was evaluated by analyzing oxidative metabolites of indinavir and glutathione (GSH) conjugates of clozapine and 4-ethylphenol in liver microsome incubations. Results showed that the MIM-EPI-based data mining approach allowed for comprehensive detection of metabolites based on predicted protonated molecules, product ions or neutral losses without predetermination of the parent drug MS/MS spectra. Additionally, it enabled metabolite detection and MS/MS acquisition in a single injection. This approach is potentially useful in high-throughout screening of metabolic soft spots and reactive metabolites at the drug discovery stage. PMID:19418486

  19. Prospects for Ultra-Stable Timekeeping with Sealed Vacuum Operation in Multi-Pole Linear Ion Trap Standards

    NASA Technical Reports Server (NTRS)

    Burt, Eric A.; Tjoelker, R. L.

    2007-01-01

    A recent long-term comparison between the compensated multi-pole Linear Ion Trap Standard (LITS) and the laser-cooled primary standards via GPS carrier phase time transfer showed a deviation of less than 2.7x10(exp -17)/day. A subsequent evaluation of potential drift contributors in the LITS showed that the leading candidates are fluctuations in background gases and the neon buffer gas. The current vacuum system employs a "flow-through" turbomolecular pump and a diaphragm fore pump. Here we consider the viability of a "sealed" vacuum system pumped by a non-evaporable getter for long-term ultra-stable clock operation. Initial tests suggests that both further stability improvement and longer mean-time-between-maintenance can be achieved using this approach

  20. Linear, non-linear optical susceptibilities and the hyperpolarizability of the mixed crystals Ag(0.5)Pb(1.75)Ge(S(1-x)Se(x))4: experiment and theory.

    PubMed

    Reshak, A H; Kogut, Y M; Fedorchuk, A O; Zamuruyeva, O V; Myronchuk, G L; Parasyuk, O V; Kamarudin, H; Auluck, S; Plucinski, K J; Bila, Jiri

    2013-11-21

    As the starting point for a comprehensive theoretical investigation of the linear and nonlinear optical susceptibilities, we have used our experimental crystallographic data for Ag0.5Pb1.75GeS3Se (Ag2Pb7Ge4S12Se4) reported. The experimental crystallographic positions were optimized by minimizing the forces acting on each atom to get meaningful theoretical predictions of the optical properties. The linear optical susceptibilities are calculated. We find that the optical band gap shows very good agreement with our measured gap. The second-order nonlinear optical (NLO) susceptibilities dispersion namely the optical second harmonic generation (SHG) is calculated and compared with our experimental measurements. The microscopic first order hyperpolarizability, β123, vector component along the principal dipole moment directions for the χ((2))(123)(ω) component was obtained theoretically and compared with our measured values at different temperatures. The dependence of the two-photon absorption (TPA) for the pump-probing at SHG of the microsecond CO2 laser was measured. In addition we explored the linear electro-optical effect in these crystals. This effect is described by the third rank polar tensors similarly to the SHG. However, for the Pockels effect besides the electronic contribution, the phonon subsystem also begins to play a principal role. As a consequence we study the dispersion of the linear electro-optical effects in the mentioned crystals. PMID:24097293