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Sample records for linear ion crystals

  1. Crystallization of Ca+ ions in a linear rf octupole ion trap

    NASA Astrophysics Data System (ADS)

    Okada, Kunihiro; Yasuda, Kazuhiro; Takayanagi, Toshinobu; Wada, Michiharu; Schuessler, Hans A.; Ohtani, Shunsuke

    2007-03-01

    A laser-cooling experiment with Ca+ ions trapped in a linear rf octupole ion trap is presented. The phase transition of the laser-cooled Ca+ ions from the cloud to the crystal state is observed by an abrupt dip of the laser-induced fluorescence spectrum and indicates that mK temperatures are obtained. We have also performed molecular dynamics simulations under various conditions to confirm this property by deducing axially symmetric structures of Coulomb crystals and by evaluating the translational temperatures of the laser-cooled ions. The simulation results show that for small numbers of ions novel ring-shaped crystals are produced. As the number of ions is increased, cylindrical layers in the ring crystal are sequentially formed. For more than 100 ions, also hexagonal and spiral structures emerge in parts of the large-size ion crystal, which has a length on the order of millimeters for the present geometrical arrangement and voltages. An advantage of the linear rf octupole trap is its large almost-field-free region in the middle of the trap, where the micromotion amplitude is small for trapped ions. These results demonstrate that such a multipole trap has attractive features for quantum computing and ultracold ion-atom collision studies.

  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.

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

    SciTech Connect

    Liang, J.; Haljan, P. C.

    2011-06-15

    Laser-cooled arrays or crystals of {sup 171}Yb{sup +} ions containing a single impurity, {sup 172}Yb{sup +} 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 {sup 171}Yb{sup +} 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. Linear expansion of the eigenvalues of a Hermitian matrix and its application to the analysis of the electronic spectra of 3 d ions in crystals

    NASA Astrophysics Data System (ADS)

    Seijo, L.; Pueyo, L.

    1985-02-01

    It is shown that the eigenvalues Ei of a Hermitian matrix H with matrix elements Hij = ΣkAkijak, where Akij are known numbers and ak a set of parameters, can be exactly expanded as E i = Σ k( {∂E i}/{∂a k})a k. This property is applied to the analysis of the optical spectra of transition metal ions in crystals proposed by L. Pueyo, M. Bermejo, and J. W. Richardson ( J. Solid State Chem.31, 217, 1980), and it is shown that this method represents the best fit of the Hamiltonian eigenvalues to the observed (or calculated) spectrum. Further advantages of using this property, in connection with the spectral analysis, are the minimization of the errors associated with the numerical approximations and a reduction in computer time. In the molecular orbital calculation of the optical or uv spectra of these systems, this linear expansion of the eigenvalues give a detailed interpretation of the improvements produced by refined calculations, such as those including configuration interaction. In particular, the changes in one-electron energy and in open-shell repulsion interactions associated with the refinement can be clearly and easily formulated. As examples, the computed spectra of CrF 4-6 and CrF 3-6 are discussed.

  6. Coulomb crystallization of highly charged ions.

    PubMed

    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

    2015-03-13

    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 (40)Ar(13+)) 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 Ar(13+) 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.

  7. 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

  8. 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."

  9. Microfabricated linear Paul-Straubel ion trap

    DOEpatents

    Mangan, Michael A [Albuquerque, NM; Blain, Matthew G [Albuquerque, NM; Tigges, Chris P [Albuquerque, NM; Linker, Kevin L [Albuquerque, NM

    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.

  10. Space-time crystals of trapped ions.

    PubMed

    Li, Tongcang; Gong, Zhe-Xuan; Yin, Zhang-Qi; Quan, H T; Yin, Xiaobo; Zhang, Peng; Duan, L-M; Zhang, Xiang

    2012-10-19

    Spontaneous symmetry breaking can lead to the formation of time crystals, as well as spatial crystals. Here we propose a space-time crystal of trapped ions and a method to realize it experimentally by confining ions in a ring-shaped trapping potential with a static magnetic field. The ions spontaneously form a spatial ring crystal due to Coulomb repulsion. This ion crystal can rotate persistently at the lowest quantum energy state in magnetic fields with fractional fluxes. The persistent rotation of trapped ions produces the temporal order, leading to the formation of a space-time crystal. We show that these space-time crystals are robust for direct experimental observation. We also study the effects of finite temperatures on the persistent rotation. The proposed space-time crystals of trapped ions provide a new dimension for exploring many-body physics and emerging properties of matter.

  11. Optical surfacing via linear ion source

    NASA Astrophysics Data System (ADS)

    Wu, Lixiang; Wei, Chaoyang; Shao, Jianda

    2017-04-01

    We present a concept of surface decomposition extended from double Fourier series to nonnegative sinusoidal wave surfaces, on the basis of which linear ion sources apply to the ultra-precision fabrication of complex surfaces and diffractive optics. The modified Fourier series, or sinusoidal wave surfaces, build a relationship between the fabrication process of optical surfaces and the surface characterization based on power spectral density (PSD) analysis. Also, we demonstrate that the one-dimensional scanning of linear ion source is applicable to the removal of mid-spatial frequency (MSF) errors caused by small-tool polishing in raster scan mode as well as the fabrication of beam sampling grating of high diffractive uniformity without a post-processing procedure. The simulation results show that optical fabrication with linear ion source is feasible and even of higher output efficiency compared with the conventional approach.

  12. 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.

  13. 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.

  14. Miniaturized Linear Wire Ion Trap Mass Analyzer.

    PubMed

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

    2016-08-02

    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.

  15. 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.

  16. 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.

  17. 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.

  18. Coulomb crystallization of sympathetically cooled highly charged ions

    NASA Astrophysics Data System (ADS)

    Crespo López-Urrutia, José R.

    2015-05-01

    Wave functions of inner-shell electrons significantly overlap with the nucleus, whereby enormously magnified relativistic, quantum electrodynamic (QED) and nuclear size effects emerge. In highly charged ions (HCI), the relative reduction of electronic correlations contributions improves the visibility of these effects. This well known facts have driven research efforts with HCI, yet the typically high temperatures at which these can be prepared in the laboratory constitutes a serious hindrance for application of laser spectroscopic methods. The solution for this, cooling HCI down to crystallization has remained an elusive target for more than two decades. By applying laser cooling to an ensemble of Be+ ions, we build Coulomb crystals that we use for stopping the motion of HCI and for cooling them. HCI, in this case Ar13+ ions are extracted from an electron beam ion trap with an energy spread of a few 100's of eV, due to the ion temperature within the trap. Carefully timed electric pulses in a potential-gradient decelerate and bunch the HCI. We achieve Coulomb crystallization of these HCI by re-trapping them in a cryogenic linear radiofrequency trap where they are sympathetically cooled through Coulomb interaction with the directly laser-cooled ensemble. Furthermore, we also demonstrate cooling of a single Ar13+ ion by a single Be+ ion, prerequisite for quantum logic spectroscopy with potentially 10-19 relative accuracy. The strongly suppressed thermal motion of the embedded HCI offers novel possibilities for investigation of questions related to the time variation of fundamental constants, parity non-conservation effects, Lorentz invariance and quantum electrodynamics. Achieving a seven orders-of-magnitude decrease in HCI temperature, from the starting point at MK values in the ion source down to the mK range within the Coulomb crystal eliminates the major obstacle for HCI investigation with high precision laser spectroscopy and quantum computation schemes.

  19. 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.

  20. Sympathetic cooling in a large ion crystal

    NASA Astrophysics Data System (ADS)

    Lin, Guin-Dar; Duan, L.-M.

    2016-12-01

    We analyze the dynamics and steady state of a linear ion array when some of the ions are continuously laser cooled. We calculate the ions' local temperature measured by its position fluctuation under various trapping and cooling configurations, taking into account background heating due to the noisy environment. For a large system, we demonstrate that by arranging the cooling ions evenly in the array, one can suppress the overall heating considerably. We also investigate the effect of different cooling rates and find that the optimal cooling efficiency is achieved by an intermediate cooling rate. We discuss the relaxation time for the ions to approach the steady state, and show that with periodic arrangement of the cooling ions, the cooling efficiency does not scale down with the system size.

  1. Fragmentation of ions in a low pressure linear ion trap.

    PubMed

    Collings, Bruce A

    2007-08-01

    The efficiency of in-trap fragmentation in a low-pressure linear ion trap (LIT), using dipolar excitation, is dependent upon the choice of both the excitation q and the drive frequency of the quadrupole. In the work presented here, fragmentation efficiencies have been measured as a function of excitation q for drive frequencies of 816 kHz and 1.228 MHz. The experiments were carried out by fragmenting reserpine (609.23-->448.20 Th and 397.21-->365.19 Th transitions) and caffeine (195-->138 Th and 138-->110 Th transitions). The data showed that the onset of efficient fragmentation occurred at a lower Mathieu q for the LIT operated at 1.228 MHz when compared with the LIT operated at 816 kHz. A comparison of the fragmentation efficiency curves as a function of pseudo-potential well depth showed that the onset of fragmentation is independent of the drive frequency. In addition, a comparison of the fragmentation efficiency curves showed that all four of the precursor ions fragmented within a range of four V of pseudo-potential well depth. The choice of an appropriate excitation q can then be determined based upon a minimum pseudo-potential well depth, quadrupole field radius, drive frequency, and the mass of interest. Fragmentation efficiencies were also found to be significantly greater when using the higher drive frequency.

  2. Waveguides based on linear defects in metal electromagnetic crystals

    NASA Astrophysics Data System (ADS)

    Vetluzhskii, A. Yu.

    2017-01-01

    Waveguides that represent linear defects in 2D metal photonic crystals are considered. Guiding properties of such structures at the frequencies of the first allowed band are demonstrated. The physical effect leading to the localization of radiation in defect area in the crystal is discussed.

  3. Effects of ion motion on linear Landau damping

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Sheng, Zheng-Ming; Kong, Xiang-Mu; Su, Fu-Fang

    2017-02-01

    The effects of ion motion on Landau damping has been studied by the use of one-dimensional Vlasov-Poisson simulation. It is shown that the ion motion may significantly change the development of the linear Landau damping. When the ion mass is multiple of proton mass, its motion will halt the linear Landau damping at some time due to the excitation of ion acoustic waves. The latter will dominate the system evolution at the later stage and hold a considerable fraction of the total energy in the system. With very small ion mass, such as in electron-positron plasma, the ion motion can suppress the linear Landau damping very quickly. When the initial field amplitude is relatively high such as with the density perturbation amplitude δn/n0 > 0.1, the effect of ion motion on Landau damping is found to be weak or even ignorable.

  4. 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.

  5. 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).

  6. 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

  7. 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].

  8. 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.

  9. Ion capturing/ion releasing films and nanoparticles in liquid crystal devices

    NASA Astrophysics Data System (ADS)

    Garbovskiy, Yuriy

    2017-01-01

    Nanoparticles dispersed in liquid crystals can change the concentration of mobile ions through the adsorption/desorption process. In the majority of the reported cases, the effects of nanoparticles on the electrical properties of liquid crystals are analysed, neglecting the interactions of ions with substrates. In this paper, the combined effect of nanoparticles and substrates on the concentration of ions in liquid crystals is discussed. Depending on the ionic purity of substrates and nanoparticles, the ion capturing/ion releasing regimes can be achieved. In addition, the concentration of mobile ions in liquid crystal nanocolloids also depends on the cell thickness.

  10. Non-linear optical titanyl arsenates: Crystal growth and properties

    NASA Astrophysics Data System (ADS)

    Nordborg, Jenni Eva Louise

    Crystals are appreciated not only for their appearance, but also for their unique physical properties which are utilized by the photonic industry in appliances that we come across every day. An important part of enabling the technical use of optical devices is the manufacture of crystals. This dissertation deals with a specific group of materials called the potassium titanyl phosphate (KIP) family, known for their non-linear optical and ferroelectric properties. The isomorphs vary in their linear optical and dielectric properties, which can be tuned to optimize device performance by forming solid solutions of the different materials. Titanyl arsenates have a wide range of near-infrared transmission which makes them useful for tunable infrared lasers. The isomorphs examined in the present work were primarily RbTiOASO4 (RTA) and CsTiOAsO4 (CTA) together with the mixtures RbxCs 1-xTiOAsO4 (RCTA). Large-scale crystals were grown by top seeding solution growth utilizing a three-zone furnace with excellent temperature control. Sufficiently slow cooling and constant upward lifting produced crystals with large volumes useable for technical applications. Optical quality RTA crystals up to 10 x 12 x 20 mm were grown. The greater difficulty in obtaining good crystals of CTA led to the use of mixed RCTA materials. The mixing of rubidium and cesium in RCTA is more favorable to crystal growth than the single components in pure RTA and CTA. Mixed crystals are rubidium-enriched and contain only 20-30% of the cesium concentration in the flux. The cesium atoms show a preference for the larger cation site. The network structure is very little affected by the cation substitution; consequently, the non-linear optical properties of the Rb-rich isomorphic mixtures of RTA and CTA can be expected to remain intact. Crystallographic methods utilizing conventional X-ray tubes, synchrotron radiation and neutron diffraction have been employed to investigate the properties of the atomic

  11. Blue phase liquid crystals stabilized by linear photo-polymerization

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    Stabilizing a photopolymer-embedded blue phase liquid crystal precursor with linearly polarized UV light is investigated experimentally. When the UV polarization axis is perpendicular to the stripe electrodes of an in-plane-switching 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 ˜2× 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.

  12. Luminescence of potassium sulphate crystals doped by Eu3+ ions

    NASA Astrophysics Data System (ADS)

    Koketai, T.; Tussupbekova, A.; Baltabekov, A.; Mussenova, E.

    2017-01-01

    This paper presents results of the study some spectral-luminescent properties of potassium sulphate crystals activated europium trivalent ions. The observed changes might be connected with the fact of crystals having Eu3+ ions and NO3 - impurity ions. There was a proposition of the possibility of selective creation of impurity centers with the help of using various salts is normal for all the transition metal ions.

  13. Differentially pumped dual linear quadrupole ion trap mass spectrometer

    DOEpatents

    Owen, Benjamin C.; Kenttamaa, Hilkka I.

    2016-11-15

    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.

  14. Differentially pumped dual linear quadrupole ion trap mass spectrometer

    DOEpatents

    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.

  15. On the Linear Stability of Crystals in the Schrödinger-Poisson Model.

    PubMed

    Komech, A; Kopylova, E

    2016-01-01

    We consider the Schrödinger-Poisson-Newton equations for crystals with one ion per cell. We linearize this dynamics at the periodic minimizers of energy per cell and introduce a novel class of the ion charge densities that ensures the stability of the linearized dynamics. Our main result is the energy positivity for the Bloch generators of the linearized dynamics under a Wiener-type condition on the ion charge density. We also adopt an additional 'Jellium' condition which cancels the negative contribution caused by the electrostatic instability and provides the 'Jellium' periodic minimizers and the optimality of the lattice: the energy per cell of the periodic minimizer attains the global minimum among all possible lattices. We show that the energy positivity can fail if the Jellium condition is violated, while the Wiener condition holds. The proof of the energy positivity relies on a novel factorization of the corresponding Hamilton functional. The Bloch generators are nonselfadjoint (and even nonsymmetric) Hamilton operators. We diagonalize these generators using our theory of spectral resolution of the Hamilton operators with positive definite energy (Komech and Kopylova in, J Stat Phys 154(1-2):503-521, 2014, J Spectral Theory 5(2):331-361, 2015). The stability of the linearized crystal dynamics is established using this spectral resolution.

  16. 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

  17. 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

  18. Cryogenic linear Paul trap for cold highly charged ion experiments.

    PubMed

    Schwarz, M; Versolato, O O; Windberger, A; Brunner, F R; Ballance, T; Eberle, S N; Ullrich, J; Schmidt, P O; Hansen, A K; Gingell, A D; Drewsen, M; López-Urrutia, J R Crespo

    2012-08-01

    Storage and cooling of highly charged ions require ultra-high vacuum levels obtainable by means of cryogenic methods. We have developed a linear Paul trap operating at 4 K capable of very long ion storage times of about 30 h. A conservative upper bound of the H(2) partial pressure of about 10(-15) mbar (at 4 K) is obtained from this. External ion injection is possible and optimized optical access for lasers is provided, while exposure to black body radiation is minimized. First results of its operation with atomic and molecular ions are presented. An all-solid state laser system at 313 nm has been set up to provide cold Be(+) ions for sympathetic cooling of highly charged ions.

  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. 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

  1. 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.

  2. 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.

  3. Mathematical Simulation of the Crystallization Process in a Continuous Linear Crystallizer

    NASA Astrophysics Data System (ADS)

    Veselov, S. N.; Volk, V. I.; Kashcheev, V. A.; Podymova, T. V.; Posenitskiy, E. A.

    2017-01-01

    A mathematical model of the crystallization of uranium in a continuous linear crystallizer, designed for the crystallization separation of desired products in the processing of an irradiated nuclear fuel, is proposed. This model defines the dynamics of growth/dissolution of uranyl nitrate hexahydrate crystals in a nitric acid solution of uranyl nitrate. Results of a numerical simulation of the indicated process, pointing to the existence of stationary conditions in the working space of the crystallizer, are presented. On the basis of these results, the characteristic time of establishment of the stationary regime at different parameters of the process was estimated. The mathematical model proposed was validated on the basis of a comparison of the results of calculations carried out within its framework with experimental data.

  4. 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.

  5. 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.

  6. Ion-number-density-dependent effects on hyperfine transition of trapped 199Hg+ ions in quadrupole linear ion traps

    NASA Astrophysics Data System (ADS)

    Yang, Zhihui; Chen, Yihe; Yan, Bibo; Wang, Man; Wan, Yongquan; Liu, Hao; She, Lei; Li, Jiaomei

    2017-04-01

    The ion-number-density-dependent frequency offsets and broadening of the ground state hyperfine transition spectra of trapped 199Hg+ ions were measured as a function of the end-cap voltage of the quadrupole linear ion trap. The number density of trapped 199Hg+ ions in the quadrupole linear trap was controlled by the end-cap voltage. The fractional frequency stability of 199Hg+ hyperfine transition to the 1 mV end-cap voltage variation was preliminary estimated to be less than 1 ×10-16. The causes of the ion-number-density-dependent frequency shift and spectrum broadening were analyzed theoretically and explained.

  7. 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.

  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. Simulation of Uranyl Nitrate Crystallization Process in Linear Crystallizer Using Simsar Software

    NASA Astrophysics Data System (ADS)

    Ochoa Bique, A.; Gozhimov, A.; Chursin, Yu; Schmidt, O.

    2016-08-01

    The paper deals with simulation of linear crystallizer work process for the research of technic operating modes and searching the most effective for material's nano-purity achievement. The model is realized by using SimSar software. Importance of device's geometry and process variables are marked. The model was included in the complex's composition of closed nuclear fuel cycle.

  10. Hydrogen/deuterium exchange of myoglobin ions in a linear quadrupole ion trap.

    PubMed

    Mao, Dunmin; Ding, Chuanfan; Douglas, D J

    2002-01-01

    The hydrogen/deuterium (H/D) exchange of gas-phase ions of holo- and apo-myoglobin has been studied by confining the ions in a linear quadrupole ion trap with D(2)O or CD(3)OD at a pressure of several mTorr. Apo-myoglobin ions were formed by collision-induced dissociation of holo-myoglobin ions between the orifice and skimmer of the ion sampling system. The exchange takes place on a time scale of seconds. Earlier cross section measurements have shown that holo-myoglobin ions can have more compact structures than apo-myoglobin. Despite this, both holo-myoglobin and apo-myoglobin in charge states +8 to +14 are found to exchange nearly the same number of hydrogens (ca. 103) in 4 s. It is possible the ions fold or unfold to new conformations on the much longer time scale of the exchange experiment compared with the cross section measurements.

  11. 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.

  12. Linear mode-mixing of phonons with trapped ions

    NASA Astrophysics Data System (ADS)

    Marshall, Kevin; James, Daniel F. V.

    2017-01-01

    We propose a method to manipulate the normal modes in a chain of trapped ions using only two lasers. Linear chains of trapped ions have proven experimentally to be highly controllable quantum systems with a variety of refined techniques for preparation, evolution, and readout; however, typically for quantum information processing applications people have been interested in using the internal levels of the ions as the computational basis. We analyze the case where the motional degrees of freedom of the ions are the quantum system of interest, and where the internal levels are leveraged to facilitate interactions. In particular, we focus on an analysis of mode-mixing of phonons in different normal modes to mimic the quantum optical equivalent of a beam splitter.

  13. Facilitated Ion Transport in Smectic Ordered Ionic Liquid Crystals

    SciTech Connect

    Lee, Jin Hong; Han, Kee Sung; Lee, Je Seung; Lee, Albert S.; Park, Seo Kyung; Hong, Sung Yun; Lee, Jong-Chan; Mueller, Karl T.; Hong, Soon Man; Koo, Chong Min

    2016-09-08

    We investigated a novel ionic mixture of an imidazolium-based room temperature IL containing ethylene oxide functionalized phosphite anion and a lithium salt that self-assembles into a smectic-ordered IL crystal. The two key features in this work are the unique origin of the smectic order of the ionic mixtures and the facilitated ion transport behavior in the smectic ordered IL crystal. In fact, the IL crystals are self-assembled through Coulombic interactions between ion species, not through the hydrophilic-phobic interactions between charged ion heads and hydrophobic long alkyl pendants or the steric interaction between mesogenic moieties. Furthermore, the smectic order in the IL crystal ionogel facilitates exceptional and remarkable ionic transport. Large ionic conductivity, viscoelastic robustness, and additional electrochemical stability of the IL crystal ionogels provide promising opportunities for future electrochemical applications.

  14. Facilitated Ion Transport in Smectic Ordered Ionic Liquid Crystals.

    PubMed

    Lee, Jin Hong; Han, Kee Sung; Lee, Je Seung; Lee, Albert S; Park, Seo Kyung; Hong, Sung Yun; Lee, Jong-Chan; Mueller, Karl T; Hong, Soon Man; Koo, Chong Min

    2016-11-01

    A novel ionic mixture of an imidazolium-based room-temperature ionic liquid containing ethylene-oxide-functionalized phosphite anions is fabricated, which, when doped with lithium salt, self-assembles into a smectic-ordered ionic liquid crystal through Coulombic interactions between the ion species. Interestingly, the smectic order in the ionic-liquid-crystal ionogel facilitates ionic transport.

  15. 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.

  16. The effective temperature of ions stored in a linear quadrupole ion trap mass spectrometer.

    PubMed

    Donald, William A; Khairallah, George N; O'Hair, Richard A J

    2013-06-01

    The extent of internal energy deposition into ions upon storage, radial ejection, and detection using a linear quadrupole ion trap mass spectrometer is investigated as a function of ion size (m/z 59 to 810) using seven ion-molecule thermometer reactions that have well characterized reaction entropies and enthalpies. The average effective temperatures of the reactants and products of the ion-molecule reactions, which were obtained from ion-molecule equilibrium measurements, range from 295 to 350 K and do not depend significantly on the number of trapped ions, m/z value, ion trap q z value, reaction enthalpy/entropy, or the number of vibrational degrees of freedom for the seven reactions investigated. The average of the effective temperature values obtained for all seven thermometer reactions is 318 ± 23 K, which indicates that linear quadrupole ion trap mass spectrometers can be used to study the structure(s) and reactivity of ions at near ambient temperature.

  17. 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.

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

    PubMed

    Rajabi, Khadijeh

    2015-02-07

    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.

  19. Space-Time Crystals of Trapped Ions

    DTIC Science & Technology

    2012-10-15

    9Beþ ions [25]). Both laser beams are parallel to the axis of the ion ring and have waists of w0. We assume that the pulse is very weak so that on...The amplitude of the transverse momentum of each photon in a Gaussian beam with waist of w0 is about @=w0. Thus the momentum of the ion ring is...Thus the waists of lasers need to satisfy 2 ffiffiffi 2 p d=N < w0 < ffiffiffi 2 p d in order to localize the position of an ion without

  20. Copper(II) benzoate dimers coordinated by different linear alcohols - A systematic study of crystal structures

    NASA Astrophysics Data System (ADS)

    Katzsch, Felix; Münch, Alexander S.; Mertens, Florian O. R. L.; Weber, Edwin

    2014-05-01

    Three new copper(II) benzoates coordinated by 1-propanol, [Cu2(PhCOO)4(1-PrOH)2] [Cu2(PhCOO)4(H2O)2] (3), 1-butanol, [Cu2(PhCOO)4(1-BuOH)2] (4) and 1-pentanol, [Cu2(PhCOO)4(1-PentOH)2] (5) at the available metal coordination sites, have been prepared and investigated with reference to their X-ray crystal structures. In all cases, dimeric paddle-wheel complexes where two copper(II) ions are held together by four benzoates were found. Moreover, the complexes show 1-propanol and water (3), 1-butanol (4) and 1-pentanol (5) coordinated to the free coordination sites of the Cu(II) ions. The dimeric complex units are connected with each other by strong Osbnd H⋯O hydrogen bonds to form strands linked together via weaker Csbnd H⋯O and Csbnd H⋯π interactions. Comparative discussion including the redetermined crystal structures obtained from copper(II) benzoate in the presence of methanol (1) or ethanol (2) allows to draw argumentation regarding the coordination of linear alcohols in corresponding crystals of paddle-wheel complexes.

  1. Synthesis, linear optical, non-linear optical, thermal and mechanical characterizations of dye-doped semi-organic NLO crystals

    NASA Astrophysics Data System (ADS)

    Sesha Bamini, N.; Vidyalakshmy, Y.; Choedak, Tenzin; Kejalakshmy, N.; Muthukrishnan, P.; Ancy, C. J.

    2015-06-01

    Organic laser dyes Coumarin 485, Coumarin 540 and Rhodamine 590 Chloride were used to dope potassium acid phthalate crystals (KAP). Dye-doped KAP crystals with different dye concentrations such as 0.01 mM, 0.03 mM, 0.05 mM, 0.07 mM and 0.09 mM (in the KAP growth solution) were grown. The linear optical, non-linear optical, mechanical and thermal characterizations of dye-doped KAP crystals were studied and compared to understand the effect of dye and dye concentration on the KAP crystal. Absorption and emission studies of KAP and dye-doped KAP single crystals indicated the inclusion of the dye into the KAP crystal lattice. The effect of dye and its concentration on the SHG efficiency of the KAP crystal was studied using the Kurtz and Perry powder technique. It was observed that the absorption maximum wavelength and concentration of the dye used for doping the KAP single crystal decided the SHG efficiency of the dye-doped KAP single crystals. The mechanical hardness of the dye-doped and undoped (pure) KAP single crystals were studied using the Vickner’s microhardness test. It was observed that doping the KAP crystals with the laser dyes changed them from softer material to harder material. Etching studies showed an improvement in the optical quality of the KAP crystal after doping with laser dyes.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  3. Folding two dimensional crystals by swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  4. H/D exchange of gas phase bradykinin ions in a linear quadrupole ion trap.

    PubMed

    Mao, Dunmin; Douglas, D J

    2003-02-01

    The gas phase H/D exchange reaction of bradykinin ions, as well as fragment ions of bradykinin generated through collisions in an orifice skimmer region, have been studied with a linear quadrupole ion trap (LIT) reflectron time-of-flight (rTOF) mass spectrometer system. The reaction in the trap takes only tens of seconds at a pressure of few mTorr of D2O or CD3OD. The exchange rate and hydrogen exchange level are not sensitive to the trapping q value over a broad range, provided q is not close to the stability boundary (q = 0.908). The relative rates and hydrogen exchange levels of protonated and sodiated +1 and +2 ions are similar to those observed previously by others with a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer system. The doubly and triply protonated ions show multimodal isotopic distributions, suggesting the presence of several different conformations. The y fragment ions show greater exchange rates and levels than a or b ions, and when water or ammonia is lost from the fragment ions, no exchange is observed.

  5. Long ion chamber systems for the SLC (Stanford Linear Collider)

    SciTech Connect

    Rolfe, J.; Gearhart, R.; Jacobsen, R.; Jenkins, T.; McComick, D.; Nelson, R.; Reagan, D.; Ross, M.

    1989-03-01

    A Panofsky Long Ion Chamber (PLIC) is essentially a gas-filled coaxial cable, and has been used to protect the Stanford Linear Accelerator from damage caused by its electron beam, and as a sensitive diagnostic tool. This old technology has been updated and has found renewed use in the SLC. PLIC systems have been installed as beam steering aids in most parts of the SLC and are a part of the system that protects the SLC from damage by errant beams in several places. 5 refs., 3 figs., 1 tab.

  6. Crystal-chemical role of malonate ions in the structure of coordination polymers

    NASA Astrophysics Data System (ADS)

    Serezhkin, V. N.; Medvedkov, Ya. A.; Serezhkina, L. B.; Pushkin, D. V.

    2015-06-01

    In the crystal structures of the malonate-containing compounds of d- or f-metals, the C3H2O{4/2-} anions were found to exhibit 17 topologically different types of coordination to the metal atoms A, playing the role of mono-, bi-, tri-, or tetradentate ligands and forming one to seven O-A bonds. The C-C-C bond angle in the malonate ions changed from 103° to 126° and depended linearly on the dihedral angle (φCOO) between the planes of the two carboxyl groups of the anion. At φCOO < 60°, the malonate ions in the crystal structures always form six-membered metallocycles with d- or f-metal atoms, while at φCOO > 67°, they can form only four-membered metallocycles. The factors that influence the conformation of malonate ions in the structures of coordination polymers were discussed.

  7. 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.

  8. Crystallization of calcium phosphate in polyacrylamide hydrogels containing phosphate ions

    NASA Astrophysics Data System (ADS)

    Yokoi, Taishi; Kawashita, Masakazu; Kikuta, Koichi; Ohtsuki, Chikara

    2010-08-01

    Calcium phosphate crystals were formed in polyacrylamide (PAAm) hydrogels containing phosphate ions by diffusion of calcium ions from calcium nitrate (Ca(NO 3) 2) solutions covering the gels. Changes in crystalline phases and crystal morphology of calcium phosphate, and in ion concentrations of the Ca(NO 3) 2 solutions were investigated as a function of reaction time. Single or two coexisting crystalline phases of calcium phosphate, hydroxyapatite (HAp), HAp/dicalcium phosphate dihydrate (DCPD) or octacalcium phosphate (OCP)/DCPD were formed in the gels. HAp crystals are formed near the surface of the gels. The dense HAp layer and HAp/DCPD layer prevented diffusion of calcium ions from the Ca(NO 3) 2 solution, thus formation of calcium phosphate in the gel phase was inhibited. Formation of DCPD was observed to follow the formation of OCP or HAp. The size of the OCP crystals gradually increased with reaction time, while changes in size of HAp crystals were not observed. The reaction time required for DCPD formation depended on the degree of supersaturation with respect to DCPD in the systems. DCPD formed within 1 day under high supersaturation conditions, whereas it formed at 10 days in low supersaturation conditions.

  9. A micro-structured ion-implanted magnonic crystal

    SciTech Connect

    Obry, Bjoern; Pirro, Philipp; Chumak, Andrii V.; Ciubotaru, Florin; Serga, Alexander A.; Hillebrands, Burkard; Braecher, Thomas; Osten, Julia; Fassbender, Juergen

    2013-05-20

    We investigate spin-wave propagation in a microstructured magnonic-crystal waveguide fabricated by localized ion implantation. The irradiation caused a periodic variation in the saturation magnetization along the waveguide. As a consequence, the spin-wave transmission spectrum exhibits a set of frequency bands, where spin-wave propagation is suppressed. A weak modification of the saturation magnetization by 7% is sufficient to decrease the spin-wave transmission in the band gaps by a factor of 10. These results evidence the applicability of localized ion implantation for the fabrication of efficient micron- and nano-sized magnonic crystals for magnon spintronic applications.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Large fraction of crystal directions leads to ion channeling

    NASA Astrophysics Data System (ADS)

    Nordlund, K.; Djurabekova, F.; Hobler, G.

    2016-12-01

    It is well established that when energetic ions are moving in crystals, they may penetrate much deeper if they happen to be directed in some specific crystal directions. This `channeling' effect is utilized for instance in certain ion beam analysis methods and has been described by analytical theories and atomistic computer simulations. However, there have been very few systematic studies of channeling in directions other than the principal low-index ones. We present here a molecular dynamics-based approach to calculate ion channeling systematically over all crystal directions, providing ion `channeling maps' that easily show in which directions channeling is expected. The results show that channeling effects can be quite significant even at energies below 1 keV, and that in many cases, significant planar channeling occurs also in a wide range of crystal directions between the low-index principal ones. In all of the cases studied, a large fraction (˜20 -60 % ) of all crystal directions show channeling. A practical implication of this is that modern experiments on randomly oriented nanostructures will have a large probability of channeling. It also means that when ion irradiations are carried out on polycrystalline samples, channeling effects on the results cannot a priori be assumed to be negligible. The maps allow for easy selection of good `nonchanneling' directions in experiments or alternatively finding wide channels for beneficial uses of channeling. We implement channeling theory to also give the fraction of channeling directions in a manner directly comparable to the simulations. The comparison shows good qualitative agreement. In particular, channeling theory is very good at predicting which channels are active at a given energy. This is true down to sub-keV energies, provided the penetration depth is not too small.

  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. High-resolution excitation of ions in a low-pressure linear ion trap.

    PubMed

    Collings, B A

    2011-01-15

    An exploration of the parameters necessary to obtain high-resolution excitation, using dipolar excitation, of an ion in a linear ion trap has been undertaken in this study. These parameters included ion trap pressure, excitation amplitude, excitation period, drive frequency of the ion trap, Mathieu q value and the mass of the ion of interest. An understanding of how these parameters play a role in high-resolution excitation is necessary to the development of a method for the targeted tandem mass spectrometric (MS/MS) analysis of ions with the same nominal mass. Resonance excitation profiles with full width half maxima as narrow as 0.015 m/z units could be obtained, under the right conditions, for an ion from a homogenously substituted triazatriphosphorine at m/z 322.049, which translates into a mass resolution of >21 500. In this particular case the requirement for high resolution was a low trap pressure (3.8 × 10(-5) Torr), low excitation amplitude (3 mV), long excitation period (100 ms) and a high Mathieu q value(0.8) when using a drive frequency of 1.228 MHz. Similar conditions were used to demonstrate the isolation of individual [M + H](+) component ions from mixtures of bromazepam (m/z 316.008)/chlorprothixene (m/z 316.0921)/fendiline (m/z 316.206) and chlorprothixene (m/z 316.0921)/oxycodone (m/z 316.1543)/fendiline (m/z 316.206) prior to obtaining product ion spectra with excitation at q = 0.236. In the former mixture the individual components were isolated with near 100% efficiency while in the latter mixture the isolation efficiency dropped to near 50% for the oxycodone component and to 80% for the other components.

  17. 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.

  18. Extending the Ion Capacity of a Linear Ion Trap Using Nonlinear Radio Frequency Fields.

    PubMed

    Guna, Mircea

    2015-12-01

    Mass selective axial ejection (MSAE) from a low pressure linear ion trap (LIT) is investigated in the presence of added auxiliary nonlinear radio frequency (rf) fields. Nonlinear rf fields allow ions to be ejected with high sensitivity at large excitation amplitudes and reduced deleterious effects of space charge. These permit the operation of the LIT at ion populations considerably larger than the space charge limit usually observed in the absence of the nonlinear fields while maintaining good spectral resolution and mass accuracy. Experimental data show that the greater the strength of the nonlinear field, the less the effects of space charge on mass assignment and peak width. The only deleterious effect is a slight broadening of the mass spectral peaks at the highest values of added nonlinear fields used. Graphical Abstract ᅟ.

  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. 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.

  1. 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.

  2. 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.

  3. 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.

  4. High efficiency tandem mass spectrometry analysis using dual linear ion traps.

    PubMed

    Li, Linfan; Zhou, Xiaoyu; Hager, James W; Ouyang, Zheng

    2014-10-07

    Tandem mass spectrometry (MS/MS) plays an essential role in modern chemical analysis. It is used for differentiating isomers and isobars and suppressing chemical noise, which allows high precision quantitation. The MS/MS analysis has been typically applied by isolating the target precursor ions, while disregarding other ions, followed by a fragmentation process that produces the product ions. In this study, configurations of dual linear ion traps were explored to develop high efficiency MS/MS analysis. The ions trapped in the first linear ion trap were axially, mass-selectively transferred to the second linear ion trap for MS/MS analysis. Ions from multiple compounds simultaneously introduced into the mass spectrometer could be sequentially analyzed. This development enables highly efficient use of the sample. For miniature ion trap mass spectrometers with discontinuous atmospheric pressure interfaces, the analysis speed and the quantitation precision can be significantly improved.

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

    PubMed

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

    2008-05-12

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

  6. A hand-portable digital linear ion trap mass spectrometer.

    PubMed

    Xue, Bing; Sun, Lulu; Huang, Zhengxu; Gao, Wei; Fan, Rongrong; Cheng, Ping; Ding, Li; Ma, Li; Zhou, Zhen

    2016-10-07

    A hand-portable digital linear ion trap mass spectrometer (DLIT-MS) has been developed for VOC analysis. It has a weight of 18 kg with dimensions of 49 cm × 39 cm × 16 cm, and consumes an average power of ca. 60 W. As a result of the introduction of a digital waveform, the DLIT-MS can be driven at a lower voltage (±100 V) to cover a mass range of 30-300 Th with a unit resolution. Compact electronics has been designed to control the DLIT-MS and record mass spectra. The mass drift was reduced after the improvement in electronics to stabilize the digital waveform voltage during the mass scan. Tandem mass spectrometry (MS) has been achieved by using digital asymmetric waveform isolation (DAWI), forward and reverse scan, and collision induced dissociation (CID). The isolation and CID efficiency for methyl salicylate were 83.9% and 81.3%, respectively. A novel buffer gas inlet system was designed to enhance the sensitivity and allow easy and safe use of the instrument. Limits of detection below 1 ppbv were obtained for several mixed gaseous samples.

  7. Ion implantation of CdTe single crystals

    NASA Astrophysics Data System (ADS)

    Wiecek, Tomasz; Popovich, Volodymir; Bester, Mariusz; Kuzma, Marian

    2016-12-01

    Ion implantation is a technique which is widely used in industry for unique modification of metal surface for medical applications. In semiconductor silicon technology ion implantation is also widely used for thin layer electronic or optoelectronic devices production. For other semiconductor materials this technique is still at an early stage. In this paper based on literature data we present the main features of the implantation of CdTe single crystals as well as some of the major problems which are likely to occur when dealing with them. The most unexpected feature is the high resistance of these crystals against the amorphization caused by ion implantation even at high doses (1017 1/cm2). The second property is the disposal of defects much deeper in the sample then it follows from the modeling calculations. The outline of principles of the ion implantation is included in the paper. The data based on RBS measurements and modeling results obtained by using SRIM software were taken into account.

  8. 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.

  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. Linearly polarized single-mode Nd:YAG oscillators using [100]- and [110]-cut crystals.

    PubMed

    Tünnermann, Henrik; Puncken, Oliver; Wessels, Peter; Frede, Maik; Neumann, Jörg; Kracht, Dietmar

    2011-07-04

    The output power and efficiency of linearly polarized high power Nd:YAG lasers is limited by depolarization and bifocusing. Both effects degrade the beam quality and decrease the output power. In a single pass configuration, [100]- and [110]-cut crystals can be used to reduce the depolarization. Here, we compare [100]-, [110]- and [111]-cut crystals in an oscillator configuration. As expected it was possible to reduce the depolarization loss by using [100]-cut crystals in our configuration, while the depolarization loss was higher for [110]-cut crystals. The thermal lens establishing in these crystals is not circular, which can degrade beam quality in high power operation.

  11. 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.

  12. 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.

  13. 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.

  14. Performance Evaluation of a Dual Linear Ion Trap-Fourier Transform Ion Cyclotron Resonance Mass Spectrometer for Proteomics Research

    PubMed Central

    Weisbrod, Chad R.; Hoopmann, Michael R.; Senko, Michael W.; Bruce, James E.

    2014-01-01

    A novel dual cell linear ion trap Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) and its performance characteristics are reported. A linear ion trap-Fourier transform ion cyclotron resonance mass spectrometer has been modified to incorporate a LTQ-Velos mass spectrometer. This modified instrument features efficient ion accumulation and fast MS/MS acquisition capabilities of dual cell linear RF ion trap instruments coupled to the high mass accuracy, resolution, and dynamic range of a FT-ICR for improved proteomic coverage. The ion accumulation efficiency is demonstrated to be an order of magnitude greater than that observed with LTQ-FT Ultra instrumentation. The proteome coverage with yeast was shown to increase over the previous instrument generation by 50% (100% increase on the peptide level). In addition, many lower abundance level yeast proteins were only detected with this modified instrument. This novel configuration also enables beam type CID fragmentation using a dual cell RF ion trap mass spectrometer. This technique involves accelerating ions between traps while applying an elevated DC offset to one of the traps to accelerate ions and induce fragmentation. This instrument design may serve as a useful option for labs currently considering purchasing new instrumentation or upgrading existing instruments. PMID:23590889

  15. Nonlinear pulse propagation phenomena in ion-doped dielectric crystals

    NASA Astrophysics Data System (ADS)

    Demeter, Gabor; Kis, Zsolt; Hohenester, Ulrich

    2012-03-01

    We theoretically analyze pulse propagation in a medium of inhomogeneously broadened two-level quantum systems, which have a vibrational degree of freedom with respect to the center-of-mass coordinate. This system mimics local mode oscillations of rare-earth-metal-ion dopants in dielectric crystals that are coupled to electronic transitions. We show the emergence of various nonlinear optical phenomena, such as self-induced transparency or the nonlinear interaction between two pulses coupling to different electrovibrational transitions. Interaction between the pulses makes it possible to generate various Raman sidebands of the incident fields and to tune the location where they are generated. We also demonstrate controlled population transfer between electrovibrational states of the ions at specific points along the propagation axis. Similarities and differences between our results and other pulse propagation phenomena of few-level quantum systems are discussed.

  16. Modifications of gallium phosphide single crystals using slow highly charged ions and swift heavy ions

    NASA Astrophysics Data System (ADS)

    El-Said, A. S.; Wilhelm, R. A.; Heller, R.; Akhmadaliev, Sh.; Schumann, E.; Sorokin, M.; Facsko, S.; Trautmann, C.

    2016-09-01

    GaP single crystals were irradiated with slow highly charged ions (HCI) using 114 keV 129Xe(33-40)+ and with various swift heavy ions (SHI) of 30 MeV I9+ and 374 MeV-2.2 GeV 197Au25+. The irradiated surfaces were investigated by scanning force microscopy (SFM). The irradiations with SHI lead to nanohillocks protruding from the GaP surfaces, whereas no changes of the surface topography were observed after the irradiation with HCI. This result indicates that a potential energy above 38.5 keV is required for surface nanostructuring of GaP. In addition, strong coloration of the GaP crystals was observed after irradiation with SHI. The effect was stronger for higher energies. This was confirmed by measuring an increased extinction coefficient in the visible light region.

  17. Ion Coulomb crystals: from quantum technology to chemistry close to the absolute zero point

    NASA Astrophysics Data System (ADS)

    Dulieu, O.; Willitsch, S.

    2017-03-01

    Ion Coulomb crystals are ordered structures of atomic or molecular ions stored in ion traps at temperatures close to the absolute zero point. These unusual "crystals" form the basis of extremely accurate clocks, provide an environment for precise studies of chemical reactions and enable advanced implementations of the technology for a quantum computer. In this article, we discuss the techniques for generating atomic and molecular Coulomb crystals and highlight some of their applications.

  18. 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.

  19. 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.

  20. 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%.

  1. 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.

  2. Negative hydrogen ions in a linear helicon plasma device

    NASA Astrophysics Data System (ADS)

    Corr, Cormac; Santoso, Jesse; Samuell, Cameron; Willett, Hannah; Manoharan, Rounak; O'Byrne, Sean

    2015-09-01

    Low-pressure negative ion sources are of crucial importance to the development of high-energy (>1 MeV) neutral beam injection systems for the ITER experimental tokamak device. Due to their high power coupling efficiency and high plasma densities, helicon devices may be able to reduce power requirements and potentially remove the need for caesium. In helicon sources, the RF power can be coupled efficiently into the plasma and it has been previously observed that the application of a small magnetic field can lead to a significant increase in the plasma density. In this work, we investigate negative ion dynamics in a high-power (20 kW) helicon plasma source. The negative ion fraction is measured by probe-based laser photodetachment, electron density and temperature are determined by a Langmuir probe and tuneable diode laser absorption spectroscopy is used to determine the density of the H(n = 2) excited atomic state and the gas temperature. The negative ion density and excited atomic hydrogen density display a maximum at a low applied magnetic field of 3 mT, while the electron temperature displays a minimum. The negative ion density can be increased by a factor of 8 with the application of the magnetic field. Spatial and temporal measurements will also be presented. The Australian Research Grants Council is acknowledged for funding.

  3. Raman study of uniaxial deformation of single-crystal mats of ultrahigh molecular weight linear polyethylene

    NASA Astrophysics Data System (ADS)

    Zavgorodnev, Yu V.; Chvalun, S. N.; Nikolaeva, G. Yu; Sagitova, E. A.; Pashinin, P. P.; Gordeyev, S. A.; Prokhorov, K. A.

    2015-03-01

    We present for the first time a Raman spectroscopic study of the deformation process of solution-crystallized single-crystal mats of ultrahigh molecular weight linear polyethylene (UHMW PE). We study the deformed regions of the films, drawn only until the formation of the neck, and the films of much higher draw ratios, just before rupture starts. For comparison, we have also carried out Raman investigations of films produced by compression of UHMW PE powder. We have found that the uniaxial molecular orientation in the neck region of the single-crystal mat films develops more slowly as compared to the films, prepared by compression of the UHMW PE powder.

  4. 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.

  5. 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.

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

    SciTech Connect

    Darius, G.; Ban, G.; Bregeault, J.; Delahaye, P.; Desrues, Ph.; Durand, D.; Flechard, X.; Herbane, M.; Labalme, M.; LeBrun, Ch.; Lienard, E.; Mauger, F.; Merrer, Y.; Mery, 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 H{sub 2} 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.

  8. Multigenerational Broadband Collision-Induced Dissociation of Precursor Ions in a Linear Quadrupole Ion Trap

    NASA Astrophysics Data System (ADS)

    Snyder, Dalton T.; Cooks, R. Graham

    2016-12-01

    A method of fragmenting ions over a wide range of m/ z values while balancing energy deposition into the precursor ion and available product ion mass range is demonstrated. In the method, which we refer to as "multigenerational collision-induced dissociation", the radiofrequency (rf) amplitude is first increased to bring the lowest m/ z of the precursor ion of interest to just below the boundary of the Mathieu stability diagram (q = 0.908). A supplementary AC signal at a fixed Mathieu q in the range 0.2-0.35 (chosen to balance precursor ion potential well depth with available product ion mass range) is then used for ion excitation as the rf amplitude is scanned downward, thus fragmenting the precursor ion population from high to low m/ z. The method is shown to generate high intensities of product ions compared with other broadband CID methods while retaining low mass ions during the fragmentation step, resulting in extensive fragment ion coverage for various components of complex mixtures. Because ions are fragmented from high to low m/ z, space charge effects are minimized and multiple discrete generations of product ions are produced, thereby giving rise to "multigenerational" product ion mass spectra.

  9. Multigenerational Broadband Collision-Induced Dissociation of Precursor Ions in a Linear Quadrupole Ion Trap.

    PubMed

    Snyder, Dalton T; Cooks, R Graham

    2016-12-01

    A method of fragmenting ions over a wide range of m/z values while balancing energy deposition into the precursor ion and available product ion mass range is demonstrated. In the method, which we refer to as "multigenerational collision-induced dissociation", the radiofrequency (rf) amplitude is first increased to bring the lowest m/z of the precursor ion of interest to just below the boundary of the Mathieu stability diagram (q = 0.908). A supplementary AC signal at a fixed Mathieu q in the range 0.2-0.35 (chosen to balance precursor ion potential well depth with available product ion mass range) is then used for ion excitation as the rf amplitude is scanned downward, thus fragmenting the precursor ion population from high to low m/z. The method is shown to generate high intensities of product ions compared with other broadband CID methods while retaining low mass ions during the fragmentation step, resulting in extensive fragment ion coverage for various components of complex mixtures. Because ions are fragmented from high to low m/z, space charge effects are minimized and multiple discrete generations of product ions are produced, thereby giving rise to "multigenerational" product ion mass spectra. Graphical Abstract ᅟ.

  10. 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.

  11. 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

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

    DOE PAGES

    Stick, Daniel Lynn; Tabakov, Boyan; Benito, Francisco; ...

    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.

  13. Development of a linear ion trap/orthogonal-time-of-flight mass spectrometer for time-dependent observation of product ions by ultraviolet photodissociation of peptide ions.

    PubMed

    Kim, Tae-Young; Schwartz, Jae C; Reilly, James P

    2009-11-01

    A hybrid linear ion trap/orthogonal time-of-flight (TOF) mass spectrometer has been developed to observe time-dependent vacuum ultraviolet photodissociation product ions. In this apparatus, a reflectron TOF mass analyzer is orthogonally interfaced to an LTQ using rf-only octopole and dc quadrupole ion guides. Precursor ions are generated by electrospray ionization and isolated in the ion trap. Subsequently they are directed to the TOF source where photodissociation occurs and product ions are extracted for mass analysis. To detect photodissociation product ions having axially divergent trajectories, a large rectangular detector is utilized. With variation of the time between photodissociation and orthogonal extraction in the TOF source, product ions formed over a range of times after photoexcitation can be sampled. Time-dependent observation of product ions following 157 nm photodissociation of a singly charged tryptic peptide ion (NWDAGFGR) showed that prompt photofragment ions (x- and v-type ions) dominate the tandem mass spectrum up to 1 micros after the laser shot, but the intensities of low energy thermal fragment ions (y-type ions) become comparable several microseconds later. Different proton mobilization time scales were observed for arginine- and lysine-terminated tryptic peptides.

  14. Linearly first- and second-order, unconditionally energy stable schemes for the phase field crystal model

    NASA Astrophysics Data System (ADS)

    Yang, Xiaofeng; Han, Daozhi

    2017-02-01

    In this paper, we develop a series of linear, unconditionally energy stable numerical schemes for solving the classical phase field crystal model. The temporal discretizations are based on the first order Euler method, the second order backward differentiation formulas (BDF2) and the second order Crank-Nicolson method, respectively. The schemes lead to linear elliptic equations to be solved at each time step, and the induced linear systems are symmetric positive definite. We prove that all three schemes are unconditionally energy stable rigorously. Various classical numerical experiments in 2D and 3D are performed to validate the accuracy and efficiency of the proposed schemes.

  15. Dual electrospray ion source for electron-transfer dissociation on a hybrid linear ion trap-orbitrap mass spectrometer.

    PubMed

    Williams, D Keith; McAlister, Graeme C; Good, David M; Coon, Joshua J; Muddiman, David C

    2007-10-15

    A dual electrospray ionization source (ESI) has been modified to simultaneously produce cations and anions, one from each emitter, for performing rapid electron-transfer dissociation (ETD) ion/ion reactions on a hybrid linear ion trap-orbitrap mass spectrometer. Unlike the pulsed dual ESI sources that were used to generate ETD reagent ions, this source separates the emitters in space, rather than time, by physically switching which one is in front of the atmospheric inlet. The new arrangement allows for substantially enhanced spray stability and decreased switching times (ions from multiply protonated peptide cations.

  16. Characterization of non-linear Potassium crystals in the Terahertz frequency domain

    NASA Astrophysics Data System (ADS)

    Mounaix, P.; Sarger, L.; Caumes, J. P.; Freysz, E.

    2004-12-01

    Systematic measurements of the dielectric properties of KDP, KNbO3, KTP and KTA non-linear crystals in the Terahertz (THz) spectral range are presented. The index of refraction and the absorption coefficients are measured between 0.1 and 1.5 THz for different crystallographic orientations. The data are deduced from an experimental set-up based on standard Terahertz time domain spectroscopy system at room temperature. These data, key parameters for the optimization of non-linear THz generation by optical rectification as well as electro-optic detection, are analysed in term of non-linear capabilities. We finally review different methods making possible to generate THz wave in these crystals and compare their characteristics.

  17. 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.

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

    SciTech Connect

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

    1990-10-22

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

  19. Infrared multiphoton dissociation of peptide cations in a dual pressure linear ion trap mass spectrometer.

    PubMed

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

    2009-10-01

    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 x 10(-3) Torr and the second a low pressure cell operated at nominally 3 x 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 y(1) fragments and immonium ions which are not typically observed by ion trap collision induced dissociation (CID). Photodissociation efficiencies of approximately 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.

  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. 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.

  2. Ion Effects in the Electron Damping Ring of the International Linear Collider

    SciTech Connect

    Wang, L.; Raubenheimer, T.; Wolski, A.; /Liverpool U.

    2006-07-17

    Ion-induced beam instabilities and tune shifts are critical issues for the electron damping ring of the International Linear Collider (ILC). To avoid conventional ion trapping, a long gap is introduced in the electron beam by omitting a number of successive bunches out of a long train. However, the beam can still suffer from the fast ion instability, driven by ions that last only for a single passage of the electron bunches. Our study shows that the ion effects can be significantly mitigated by using multiple gaps, so that the stored beam consists of a number of relatively short bunch trains. The ion effects in the ILC damping rings are investigated using both analytical and numerical methods.

  3. Structural, optical and dielectric studies of novel non-linear Bisglycine Lithium Nitrate piezoelectric single crystal

    NASA Astrophysics Data System (ADS)

    Dalal, Jyoti; Sinha, Nidhi; Kumar, Binay

    2014-11-01

    The novel non-linear semiorganic Bisglycine Lithium Nitrate (BGLiN) single crystals were grown by slow evaporation technique. The structural analysis revealed that it belongs to non-centrosymmetric orthorhombic structure. The presence of various functional groups in the grown crystal was confirmed by FTIR and Raman analysis. Surface morphology of the grown crystal was studied by scanning electron microscopy. The optical studies show that crystal has good transmittance (more than 80%) in the entire visible region and a wide band gap (5.17 eV). The optical constants such as extinction coefficient (K), the reflectance (R) and refractive index (n) as a function of photon energy were calculated from the optical measurements. With the help of these optical constants the electric susceptibility (χc) and both the real (εr) and imaginary (εi) parts of the dielectric constants were also calculated which are required to develop optoelectronic devices. In photoluminescence studies, a broad emission band centered at 404 nm was found in addition to a small band at 352 nm. A broad transition (from 29 to 33 °C) was observed with low dielectric constant value. A high piezoelectric charge coefficient (d33) of 14 pC/N was measured at room temperature which implies its usefulness for various sensor applications. The second harmonic generation efficiency of crystal was found to be 1.5 times to that of KDP. From thermo gravimetric analysis and differential thermal analysis, thermal stability and melting point (246 °C) were investigated. The dielectric behavior, optical characterization, piezoelectric behavior and the non-linear optical properties of the Bisglycine Lithium Nitrate single crystals were reported for the first time which established the usefulness of these crystals for various piezo- and opto-electronics applications.

  4. Optimized precursor ion selection for labile ions in a linear ion trap mass spectrometer and its impact on quantification using selected reaction monitoring.

    PubMed

    Lee, Hyun-Seok; Shin, Kyong-Oh; Jo, Sung-Chan; Lee, Yong-Moon; Yim, Yong-Hyeon

    2014-12-01

    The fragmentation of fragile ions during the application of an isolation waveform for precursor ion selection and the resulting loss of isolated ion intensity is well-known in ion trap mass spectrometry (ITMS). To obtain adequate ion intensity in the selected reaction monitoring (SRM) of fragile precursor ions, a wider ion isolation width is required. However, the increased isolation width significantly diminishes the selectivity of the channels chosen for SRM, which is a serious problem for samples with complex matrices. The sensitive and selective quantification of many lipid molecules, including ceramides from real biological samples, using a linear ion trap mass spectrometer is also hindered by the same problem because of the ease of water loss from protonated ceramide ions. In this study, a method for the reliable quantification of ceramides using SRM with near unity precursor ion isolation has been developed for ITMS by utilizing alternative precursor ions generated by in-source dissociation. The selected precursor ions allow the isolation of ions with unit mass width and the selective analysis of ceramides using SRM with negligible loss of sensitivity. The quantification of C18:0-, C24:0- and C24:1-ceramides using the present method shows excellent linearity over the concentration ranges from 6 to 100, 25 to 1000 and 25 to 1000 nM, respectively. The limits of detection of C18:0-, C24:0- and C24:1-ceramides were 0.25, 0.25 and 5 fmol, respectively. The developed method was successfully applied to quantify ceramides in fetal bovine serum.

  5. Complete structural characterization of ceramides as [M-H](-) ions by multiple-stage linear ion trap mass spectrometry.

    PubMed

    Hsu, Fong-Fu

    2016-11-01

    Ceramide is a huge lipid family consisting of diversified structures including various modifications in the fatty acyl chain and the long chain base (LCB). In this contribution, negative-ion ESI linear ion-trap multiple-stage mass spectrometric method (LIT MS(n)) towards complete structural determination of ceramides in ten major families characterized as the [M-H](-) ions is described. Multiple sets of fragment ions reflecting the fatty acyl chain and LCB were observed in the CID MS(2) spectrum, while the sequential MS(3) and MS(4) spectra contain structural information for locating the double bond and the functional groups, permitting realization of the fragmentation processes. Thereby, differentiation of ceramide molecules varied by chain length, the LCB (sphingosine, phytosphigosine, 6-hydroxy-sphingosine), and by the modification (α-hydroxy-, β-hydroxy-, ω-hydroxy-FA) can be achieved; and many isomeric structures in the biological specimen can be revealed in detail.

  6. 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.

  7. Implementation of electron-transfer dissociation on a hybrid linear ion trap-orbitrap mass spectrometer.

    PubMed

    McAlister, Graeme C; Phanstiel, Doug; Good, David M; Berggren, W Travis; Coon, Joshua J

    2007-05-15

    We describe the adaptation of a hybrid quadrupole linear ion trap-orbitrap mass spectrometer to accommodate electron-transfer ion/ion reactions (ETD) for peptide and protein characterization. The method utilizes pulsed, dual electrospray ion sources and requires minimal instrument modification. Switching between cation and reagent anion injection schemes is automated and accomplished within a few hundred milliseconds. Ion/ion reactions are conducted within the linear ion trap, after which the c- and z-type product ions are passed to the orbitrap for high-resolution m/z analysis. With this arrangement, mass accuracies are typically measured to within 2 ppm at a resolving power of approximately 60 000. Using large peptides and intact proteins, we demonstrate such capabilities will accelerate our ability to interrogate high-mass species. To illustrate compatibility with automated data-dependent analysis and subsequent data processing, we couple the technique with an online chromatographic separation of a yeast whole-cell lysate followed by peptide identification using ProSight PC. Fairly long pulsing times and relatively low ET efficiency, as compared to conventional ETD instrumentation, are the main drawbacks of this approach. Still, our results suggest that the implementation of ETD on sensitive, high-resolution, and high-mass accuracy hybrid instrumentation, such as the orbitrap, will substantially propel the emergent fields of middle- and top-down proteomics.

  8. Spectroscopy of V{sup 4+} and V{sup 3+} ions in a forsterite crystal

    SciTech Connect

    Veremeichik, T F; Gaister, A V; Subbotin, Kirill A; Zharikov, Evgeny V; Protopopov, V N; Smirnov, Valerii A

    2000-05-31

    The absorption spectra of impurity vanadium ions in forsterite crystals are studied in the wavelength range from 600 to 2000 nm. It is found that the V{sup 4+} ion in the tetrahedral coordination in crystals grown by the Czochralski technique exhibits strong absorption in the range from 600 to 1200 nm. The intense electron-vibrational progressions in the absorption spectra of impurity d-ions in crystals were observed for the first time at temperatures 300 and 77 K. In the authors' opinion, these progressions appear due to the formation of the oxovanadate complex and distortions of the structural tetrahedron. The forsterite crystal doped with V{sup 4+} ions has a very high absorption cross section (up to 2.1x10{sup -18} cm{sup 2}) and a continuous broad absorption band, which makes this crystal promising as a passive laser switch in the range between 600 and 1200 nm. At the same time, the V{sup 4+} ions in the forsterite crystal do not emit luminescence because of a high probability of the nonradiative relaxation of their excited state. It is shown that luminescence of a V:Mg{sub 2}SiO{sub 4} crystal is related to the tetrahedral V{sup 3+} ion. (laser applications and other topics in quantum electronics)

  9. Crystal field effects on interionic distance in cubic MgO crystal doped with Fe2+ ions

    NASA Astrophysics Data System (ADS)

    Ivascu, S.; Gruia, A. S.; Avram, N. M.

    2014-10-01

    The exchange charge model of crystal field was applied to determine the dependence of the crystal field strength 10Dq on interionic distances R between the Fe2+ impurity ion and O2- ligands in cubic MgO:Fe2+. The obtained results were extrapolated by the power law and was shown that 10Dq depends on R as 1/R, with n=6.3486. The deviations of these values from the value n=5 (predicted by the simple point charge model of crystal field) is explained by the covalent and exchange effects between impurity ion and ligands; the contribution of these effects into the total crystal field strength was considered separately. The 10Dq functions obtained as a result of our calculations were used for estimations of the electron-vibrational constants, Huang-Rhys parameters, and Jahn-Teller stabilization energy, and compared with available literature data.

  10. 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.

  11. The Influence of the Driving Voltage and Ion Concentration on the Lateral Ion Transport in Nematic Liquid Crystal Displays

    NASA Astrophysics Data System (ADS)

    Stojmenovik, Goran; Neyts, Kristiaan; Vermael, Stefaan; Verschueren, Alwin R. M.; van Asselt, Rob

    2005-08-01

    Nematic liquid crystal displays (LCDs) contain ions that influence the electrooptical characteristics of the display. A typical super-twisted nematic (STN) display for mobile phone applications becomes darker at a standard driving frequency if it contains many impurity ions. We have discovered that ions can travel in the plane of the glass plates in the absence of a lateral electric field, leading to lateral nonhomogeneity in transmission (dark and bright stripes). In this paper, we present our research on the lateral ion transport dependence on the driving square wave (SQW) amplitude and dc component at a wide range of ion concentrations. The existence of a dc component, a high ion concentration and high SQW amplitudes increase the lateral ion speed.

  12. 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.

  13. 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.

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

    SciTech Connect

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

    2006-11-30

    The linear dispersion of the ion temperature gradient (ITG) modes, in the presence of a non uniform background ion velocity U(parallel sign) U(parallel sign)(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.

  15. The ion capturing effect of 5° SiOx alignment films in liquid crystal devices

    NASA Astrophysics Data System (ADS)

    Huang, Yi; Bos, Philip J.; Bhowmik, Achintya

    2010-09-01

    We show that SiOx, deposited at 5° to the interior surface of a liquid crystal cell allows for a surprisingly substantial reduction in the ion concentration of liquid crystal devices. We have investigated this effect and found that this type of film, due to its surface morphology, captures ions from the liquid crystal material. Ion adsorption on 5° SiOx film obeys the Langmuir isotherm. Experimental results shown allow estimation of the ion capturing capacity of these films to be more than an order of 10 000/μm2. These types of materials are useful for new types of very low power liquid crystal devices such as e-books.

  16. 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.

  17. Dependence of the lateral ion transport on the driving frequency in nematic liquid crystal displays

    NASA Astrophysics Data System (ADS)

    Stojmenovik, G.; Vermael, S.; Neyts, K.; Asselt, R. van; Verschueren, A. R. M.

    2004-10-01

    The presence of ions in a liquid crystal (LC) influences the transmission characteristics of LC displays. These ions follow the electric field perpendicular to the electrodes and move back and forth under the influence of the ac field. Because of their charge, they can distort the electric field, which leads to transmission changes. Recently it was discovered that due to the LC anisotropy, ion motion parallel with the plane of the electrodes (perpendicular to the electric field) is also possible, even without lateral fields. After driving a pixel for a long time, the ions will accumulate at one pixel edge, which leads to unwanted image artifacts. In this paper, we investigate the frequency dependence of the lateral ion transport in twisted nematic liquid crystal displays at high and low ion concentrations, different ion mobilities, and LC rotational viscosities, for a fixed voltage just above the LC threshold.

  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. Optical spectra of rare earth ions in Mg-Al spinnel crystals

    NASA Astrophysics Data System (ADS)

    Gritsyna, V. T.; Kolner, V. B.; Damburg, N. A.; Mironova, N. A.; Skvortsova, V. N.

    1985-05-01

    X-ray luminescence and photoluminescence spectra have been obtained for MgO-nAl2O3 crystals doped with alkaline rare earth elements. The crystals were grown according to the Verneuil method. Transitions are presented in Tb3(+), Dy3(+), and Er(+), Er3(+) ions in nonstoichiometric crystals, and the parameters of the corresponding luminescence lines are given. Inhomogeneous broadening of the spectral lines is attributed to deformation of polyhedra due to cation mixing and defects of the nonstoichiometric crystal structure. The X-ray and photoluminescence spectra are of the crystals are reproduced in graphic form.

  20. Ion strength limit of computed excess functions based on the linearized Poisson-Boltzmann equation.

    PubMed

    Fraenkel, Dan

    2015-12-05

    The linearized Poisson-Boltzmann (L-PB) equation is examined for its κ-range of validity (κ, Debye reciprocal length). This is done for the Debye-Hückel (DH) theory, i.e., using a single ion size, and for the SiS treatment (D. Fraenkel, Mol. Phys. 2010, 108, 1435), which extends the DH theory to the case of ion-size dissimilarity (therefore dubbed DH-SiS). The linearization of the PB equation has been claimed responsible for the DH theory's failure to fit with experiment at > 0.1 m; but DH-SiS fits with data of the mean ionic activity coefficient, γ± (molal), against m, even at m > 1 (κ > 0.33 Å(-1) ). The SiS expressions combine the overall extra-electrostatic potential energy of the smaller ion, as central ion-Ψa>b (κ), with that of the larger ion, as central ion-Ψb>a (κ); a and b are, respectively, the counterion and co-ion distances of closest approach. Ψa>b and Ψb>a are derived from the L-PB equation, which appears to conflict with their being effective up to moderate electrolyte concentrations (≈1 m). However, the L-PB equation can be valid up to κ ≥ 1.3 Å(-1) if one abandons the 1/κ criterion for its effectiveness and, instead, use, as criterion, the mean-field electrostatic interaction potential of the central ion with its ion cloud, at a radial distance dividing the cloud charge into two equal parts. The DH theory's failure is, thus, not because of using the L-PB equation; the lethal approximation is assigning a single size to the positive and negative ions.

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

    PubMed

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

    2015-09-01

    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.

  2. Ion beam damage assessment and waveguide formation induced by energetic Si-ion irradiation in lanthanum aluminate crystal

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Huang, Q.; Crespillo, M. L.; Qiao, M.; Liu, P.; Wang, X. L.

    2017-02-01

    Lanthanum aluminate (LaAlO3) crystal has emerged as one of the most valuable functional-materials, and its physical, electronic and optical properties strongly depend on the crystal structure, which can be easily altered in an irradiation environment and therefore affect the performance of LaAlO3-based devices. On the other hand, the preparation of LaAlO3 waveguide is also a scientific challenge for its potential application prospects in optoelectronics field. In this work, the damage evolution behavior of LaAlO3 crystal under Si-ion irradiation has been discussed in detail utilizing complementary characterization techniques, and then, single-mode waveguide of LaAlO3 crystal in the visible band can be obtained based on ion-irradiation-induced lattice damage behavior. Waveguide optical-coupling techniques are used to show its competitive features. Thus, novel optical waveguides with optimized features in LaAlO3 crystals can be tailored by a proper selection of ion mass, energy and fluence using the modification of the target material during ion irradiation process.

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

    DOE PAGES

    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.

  4. Surface adsorption of Cs137 ions on quartz crystals

    USGS Publications Warehouse

    Antkiw, Stephen; Waesche, H.; Senftle, F.

    1954-01-01

    Adsorption tests were made on four large synthetic and three natural quartz crystals to see if surface defects might be detected by subsequent autoradiography techniques. The adsorbent used was radioactive Cs137 in a solution of Cs 137Cl. Natural quartz crystals adsorbed more cesium than the synthetic crystals. Certain surface defects were made evident by this method, but twinning features could not be detected.

  5. Large ion Coulomb crystals: A near-ideal medium for coupling optical cavity modes to matter

    SciTech Connect

    Dantan, A.; Albert, M.; Marler, J. P.; Herskind, P. F.; Drewsen, M.

    2009-10-15

    We present an investigation of the coherent coupling of various transverse field modes of an optical cavity to ion Coulomb crystals. The obtained experimental results, which include the demonstration of identical collective coupling rates for different transverse modes of a cavity field to ions in the same large Coulomb crystal, are in excellent agreement with theoretical predictions. The results furthermore suggest that Coulomb crystals in the future may serve as near-ideal media for high-fidelity multimode quantum information processing and communication purposes, including the generation and storage of single-photon qubits encoded in different transverse modes.

  6. 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.

  7. 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.

  8. Optical properties of off-centred ? ions in ? crystals

    NASA Astrophysics Data System (ADS)

    Tsuboi, Taiju; Scacco, Augusto

    1998-03-01

    Optical absorption and magnetic circular dichroism (MCD) spectra of 0953-8984/10/12/016/img7 crystals with different concentrations of 0953-8984/10/12/016/img8 ions have been studied in the temperature range 15-296 K. Absorption bands due to isolated 0953-8984/10/12/016/img8 are observed at 27 000, 28 593, 31 250, 32 010 and 47 600 0953-8984/10/12/016/img10, and their intensities are almost constant for variation of temperature. A vibronic fine structure is observed with a sharp line at 27 460 0953-8984/10/12/016/img10 on the low energy tail of the 28 593 0953-8984/10/12/016/img10 band. From the temperature behaviour of the absorptions and MCD spectra of the intense 28 593 and 32 010 0953-8984/10/12/016/img10 bands, it is concluded that the first four bands arise from the 0953-8984/10/12/016/img14 transition of 0953-8984/10/12/016/img8 occupying an off-centred position at the 0953-8984/10/12/016/img16 site. By comparison with the 0953-8984/10/12/016/img17 absorption bands in 0953-8984/10/12/016/img18 and NaF, it is suggested that the 28 593 and 32 010 0953-8984/10/12/016/img10 bands are caused by the 0953-8984/10/12/016/img20 and 0953-8984/10/12/016/img21 transitions, respectively, while the weak 27 000 and 31 250 0953-8984/10/12/016/img10 bands are related to the triplet states 0953-8984/10/12/016/img23 and 0953-8984/10/12/016/img24. The high-energy 47 600 0953-8984/10/12/016/img10 band is proposed to be attributable to the 0953-8984/10/12/016/img26 transition.

  9. Tunable photonic band-gaps in one-dimensional photonic crystals containing linear graded index material

    NASA Astrophysics Data System (ADS)

    Singh, Bipin K.; Kumar, Pawan; Pandey, Praveen C.

    2014-12-01

    We have demonstrated control of the photonic band gaps (PBGs) in 1-D photonic crystals using linear graded index material. The analysis of PBG has been done in THz region by considering photonic crystals in the form of ten periods of second, third and fourth generation of the Fibonacci sequence as unit cell. The unit cells are constituted of two kinds of layers; one is taken of linear graded index material and other of normal dielectric material. For this investigation, we used a theoretical model based on transfer matrix method. We have obtained a large number of PBGs and their bandwidths can be tuned by changing the grading profile and thicknesses of linear graded index layers. The number of PBGs increases with increase in the thicknesses of layers and their bandwidths can be controlled by the contrast of initial and final refractive index of the graded layers. In this way, we provide more design freedom for photonic devices such as reflectors, filters, optical sensors, couplers, etc.

  10. Crystallization of calcium sulfate dihydrate in the presence of some metal ions

    NASA Astrophysics Data System (ADS)

    Hamdona, Samia K.; Al Hadad, Umaima A.

    2007-02-01

    Crystallization of calcium sulfate dihydrate (CaSO 4·2H 2O gypsum) in sodium chloride solutions in the presence of some metal ions, and over a range of relative super-saturation has been studied. The addition of metal ions, even at relatively low concentration (10 -6 mol l -1), markedly retard the rate of crystallization of gypsum. Retardation effect was enhanced with increase in the additives contents. Moreover, the effect was enhanced as the relative super-saturation decreases. Influence of mixed additives on the rate of crystallization (Cd 2++Arg, Cd 2++H 3PO 4 and Cd 2++PAA) has also been studied. Direct adsorption experiments of these metal ions on the surface of gypsum crystals have been made for comparison.

  11. Herringbone Pattern and CH-π Bonding in the Crystal Architecture of Linear Polycyclic Aromatic Hydrocarbons.

    PubMed

    Guijarro, Albert; Vergés, José A; San-Fabián, Emilio; Chiappe, Guillermo; Louis, Enrique

    2016-11-04

    The herringbone pattern is a pervasive structural motive found in most molecular crystals involving aromatic compounds. A plot of the experimental sublimation enthalpies of members of increasing size of the acene, phenacene and p-phenyl families versus the number of carbons uncovers a linear relationship between the two magnitudes, suggesting a major role of CH-π bonding. In this work we undertake the task of evaluating the relevance of the edge-to-face interaction (or CH-π bond) in the overall reticular energy of the crystal, to quantitatively assess the importance of this structural element. Following a heuristic approach, we considered the series of acenes, phenacenes and p-phenyls and analyzed the edge-to-face interaction between the molecules as they occur in the experimental crystal network. Isolation of the relevant molecular dimers allows to incorporate some of the most sophisticated tools of quantum chemistry and get a reliable picture of the isolated bond. When compared to the experimental sublimation energy, our results are conclusive: this sole interaction is the largest contribution to the lattice energy, and definitively dictates the crystal architecture in all the studied cases. Elusive enough, the edge-to-face interaction is mainly dominated by correlation interactions, specifically in the form of dispersion and, to a less extent, of charge-transfer terms. A suggestive picture of the bond has been obtained by displaying the differences in local electron densities calculated by either correlated or non-correlated methods.

  12. A Linear Single-Crystal Bragg-Fresnel Lens With SiO2 Surface Structure

    SciTech Connect

    Kuznetsov, S.; Yunkin, V.; Drakopoulos, M.; Snigireva, I.; Snigirev, A.

    2004-05-12

    Bragg-Fresnel lens (BFL) as thin silicon dioxide strips grown on the surface of perfect silicon crystal was designed, manufactured and experimentally tested. In this case the BFL structure consists of a set of silicon dioxide rectangular shape etched zones arranged by the Fresnel zone law. The stress within coated and uncoated crystal regions is opposite in sign, whether tensile or compressive. The strain in the substrate crystal lattice directly underneath discontinuities in the deposited film give rise to phase difference between waves diffracted from coated and uncoated crystal regions. This phase difference is known to be dependent on the thickness and composition of film and substrate. The focusing properties of Si/SiO2 BFLs with 107 zones and 0.3 micrometer outermost zone width were experimentally studied as a function of the silicon oxide thickness in the range of 100 - 400 nanometers. It was shown that deformation Bragg-Fresnel lenses could effectively focus hard X-rays to a linear focal spot of about 2 microns. The efficiency of focusing was found to be about 16% at energy 10 keV. The developed lens design is a promising approach to extend the angular range of focusing by Bragg-Fresnel optical elements and to avoid some drawbacks of BFL properties related to aspect-ratio dependent etching.

  13. Ferromagnetic GeMn thin film prepared by ion implantation and ion beam induced epitaxial crystallization annealing

    NASA Astrophysics Data System (ADS)

    Chen, C. H.; Niu, H.; Yan, D. C.; Hsieh, H. H.; Lee, C. P.; Chi, C. C.

    2012-06-01

    Ferromagnetic GeMn was prepared by Mn implantation followed by ion beam-induced epitaxial crystallization annealing. The damage caused by Mn implantation was repaired by subsequent helium ion irradiation. Various structural analyses were performed and Mn ions were found to incorporate uniformly into the Ge lattice without the formation of any secondary phases. The remnant magnetic moment exhibited room temperature ferromagnetism. Anomalous Hall effect and field dependent magnetization were measured at the same time at room temperature indicating spin polarized free carrier transport. Additional measurement using x-ray magnetic circular dichroism also revealed that the carriers were spin-polarized.

  14. Enhancement of Ion Activation and Collision-Induced Dissociation by Simultaneous Dipolar Excitation of Ions in x- and y-Directions in a Linear Ion Trap.

    PubMed

    Dang, Qiankun; Xu, Fuxing; Xie, Xiaodong; Xu, Chongsheng; Dai, Xinhua; Fang, Xiang; Ding, Li; Ding, Chuan-Fan

    2015-06-02

    Collision-induced dissociation (CID) in linear ion traps is usually performed by applying a dipolar alternating current (AC) signal to one pair of electrodes, which results in ion excitation mainly in one direction. In this paper, we report simulation and experimental studies of the ion excitation in two coordinate directions by applying identical dipolar AC signals to two pairs of electrodes simultaneously. Theoretical analysis and simulation results demonstrate that the ion kinetic energy is higher than that using the conventional CID method. Experimental results show that more activation energy (as determined by the intensity ratio of the a4/b4 fragments from the CID of protonated leucine enkephalin) can be deposited into parent ions in this method. The dissociation rate constant in this method was about 3.8 times higher than that in the conventional method under the same experimental condition, at the Mathieu parameter qu (where u = x, y) value of 0.25. The ion fragmentation efficiency is also significantly improved. Compared with the conventional method, the smaller qu value can be used in this method to obtain the same internal energy deposited into ions. Consequently, the "low mass cut-off" is redeemed and more fragment ions can be detected. This excitation method can be implemented easily without changing any experimental parameters.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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.

  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

    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.

  18. Fluid electron, gyrokinetic ion simulations of linear internal kink and energetic particle modes

    NASA Astrophysics Data System (ADS)

    Cole, Michael; Mishchenko, Alexey; Könies, Axel; Kleiber, Ralf; Borchardt, Matthias

    2014-07-01

    The internal kink mode is an important plasma instability responsible for a broad class of undesirable phenomena in tokamaks, including the sawtooth cycle and fishbones. To predict and discover ways to mitigate this behaviour in current and future devices, numerical simulations are necessary. The internal kink mode can be modelled by reduced magnetohydrodynamics (MHD). Fishbone modes are an inherently kinetic and non-linear phenomenon based on the n = 1 Energetic Particle Mode (EPM), and have been studied using hybrid codes that combine a reduced MHD bulk plasma model with a kinetic treatment of fast ions. In this work, linear simulations are presented using a hybrid model which couples a fluid treatment of electrons with a gyrokinetic treatment of both bulk and fast ions. Studies of the internal kink mode in geometry relevant to large tokamak experiments are presented and the effect of gyrokinetic ions is considered. Interaction of the kink with gyrokinetic fast ions is also considered, including the destabilisation of the linear n = 1 EPM underlying the fishbone.

  19. Fluid electron, gyrokinetic ion simulations of linear internal kink and energetic particle modes

    SciTech Connect

    Cole, Michael Mishchenko, Alexey; Könies, Axel; Kleiber, Ralf; Borchardt, Matthias

    2014-07-15

    The internal kink mode is an important plasma instability responsible for a broad class of undesirable phenomena in tokamaks, including the sawtooth cycle and fishbones. To predict and discover ways to mitigate this behaviour in current and future devices, numerical simulations are necessary. The internal kink mode can be modelled by reduced magnetohydrodynamics (MHD). Fishbone modes are an inherently kinetic and non-linear phenomenon based on the n = 1 Energetic Particle Mode (EPM), and have been studied using hybrid codes that combine a reduced MHD bulk plasma model with a kinetic treatment of fast ions. In this work, linear simulations are presented using a hybrid model which couples a fluid treatment of electrons with a gyrokinetic treatment of both bulk and fast ions. Studies of the internal kink mode in geometry relevant to large tokamak experiments are presented and the effect of gyrokinetic ions is considered. Interaction of the kink with gyrokinetic fast ions is also considered, including the destabilisation of the linear n = 1 EPM underlying the fishbone.

  20. 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.

  1. Linear and nonlinear optical properties of gold nanoparticle-doped photonic crystal fiber.

    PubMed

    Bigot, L; El Hamzaoui, H; Le Rouge, A; Bouwmans, G; Chassagneux, F; Capoen, B; Bouazaoui, M

    2011-09-26

    We report on the production of air/silica photonic crystal fiber doped with gold nanoparticles. The stack-and-draw technique was used to combine a gold nanoparticles-doped silica core rod synthesized by the sol-gel route with capillaries drawn from commercially available silica tubes. The presence of nanoparticles in the core region was confirmed at the different steps of the process down to the fiber geometry, even after multiple drawings at ~2000 °C. Optical properties of the fiber were investigated and put in evidence the impact of gold nanoparticles on both linear and nonlinear transmission.

  2. Linear electro-optic effect in the organic crystal 4-aminobenzophenone

    NASA Astrophysics Data System (ADS)

    Lochran, S.; Bailey, R. T.; Cruickshank, F. R.; Pugh, D.; Sherwood, J. N.

    1997-01-01

    The linear electro-optic effect in single crystals of 4-aminobenzphenone (ABP) is reported together with calibration data on LiNbO 3 . For ABP the linear electro-optic coefficients r 22 and r 32 at 488 nm were found to be 2.12 and 5.05 pm V, respectively, with the corresponding reduced half-wave voltages being 49.4 0.1 and 9.3 0.1 kV. For LiNbO 3 the half-wave voltage was found to be 4.0 0.1 kV at 632.8 nm and 2.4 0.1 kV at 488 nm.

  3. IONIC THERMOCURRENTS IN ALKALI HALIDE CRYSTALS CONTAINING SUBSTITUTIONAL BERYLLIUM IONS.

    DTIC Science & Technology

    omega - 3 and omega-4); (3) the activation energy for the diffusion of Be ions is .5 eV for NaCl and .45 eV for KCl. In discussing the results, the possibility that the Be ions occupy off-center positions is considered. (Author)

  4. Utility of Higher Harmonics in Electrospray Ionization Fourier Transform Electrostatic Linear Ion Trap Mass Spectrometry.

    PubMed

    Dziekonski, Eric T; Johnson, Joshua T; McLuckey, Scott A

    2017-03-30

    Mass resolution (M/ΔM fwhm) is observed to linearly increase with harmonic order in a Fourier transform electrostatic linear ion trap (ELIT) mass spectrometer. This behavior was predicted by Grosshans and Marshall for frequency-multiple detection in a Fourier transform ion cyclotron resonance mass spectrometer only for situations when the prominent mechanism for signal decay is ion ejection from the trap. As the analyzer pressure in our ELIT chamber is relatively high, such that collisional scattering and collision-induced dissociation are expected to underlie much of the ion loss, we sought to explore the relationship between harmonic order and mass resolution. Mass resolutions of 36 900 (fundamental), 75 850 (2nd harmonic), and 108 200 (3rd harmonic) were obtained for GdO(+) (avg. m/z 173.919) with a transient length of 300 ms. To demonstrate that the mass resolution was truly increasing with harmonic order, the unresolved isotopes at the fundamental distribution of cytochrome c(+8) (m/z ∼ 1549) were nearly baseline, resolved at the third harmonic (mass resolution ≈ 23 000) with a transient length of only 200 ms. This experiment demonstrates that, when the ion density is sufficiently low, ions with frequency differences of less than 4 Hz remain uncoalesced. Higher harmonics can be used to increase the effective mass resolution for a fixed transient length and thereby may enable the resolution of closely spaced masses, determination of a protein ion's charge state, and study of the onset of peak coalescence when the resolution at the fundamental frequency is insufficient.

  5. Controlling and measuring quantum transport of heat in trapped-ion crystals.

    PubMed

    Bermudez, A; Bruderer, M; Plenio, M B

    2013-07-26

    Measuring heat flow through nanoscale devices poses formidable practical difficulties as there is no "ampere meter" for heat. We propose to overcome this problem in a chain of trapped ions, where laser cooling the chain edges to different temperatures induces a heat current of local vibrations (vibrons). We show how to efficiently control and measure this current, including fluctuations, by coupling vibrons to internal ion states. This demonstrates that ion crystals provide an ideal platform for studying quantum transport, e.g., through thermal analogues of quantum wires and quantum dots. Notably, ion crystals may give access to measurements of the elusive bosonic fluctuations in heat currents and the onset of Fourier's law. Our results are strongly supported by numerical simulations for a realistic implementation with specific ions and system parameters.

  6. 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.

  7. 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.

  8. 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.

  9. Simplified model to describe the dissociative recombination of linear polyatomic ions of astrophysical interest

    NASA Astrophysics Data System (ADS)

    Douguet, N.; Fonseca dos Santos, S.; Kokoouline, V.; Orel, A. E.

    2015-01-01

    We present results of a theoretical study on dissociative recombination of the HCNH+, HCO+ and N2H+ linear polyatomic ions at low energies using a simple theoretical model. In the present study, the indirect mechanism for recombination proceeds through the capture of the incoming electron in excited vibrational Rydberg states attached to the degenerate transverse modes of the linear ions. The strength of the non-adiabatic coupling responsible for dissociative recombination is determined directly from the near-threshold scattering matrix obtained numerically using the complex Kohn variational method. The final cross sections for the process are compared with available experimental data. It is demonstrated that at low collision energies, the major contribution to the dissociative recombination cross section is due to the indirect mechanism.

  10. Quasi-linear analysis of ion Weibel instability in the earth's neutral sheet

    NASA Technical Reports Server (NTRS)

    Lui, Anthony T. Y.; Yoon, Peter H.; Chang, Chia-Lie

    1993-01-01

    A quasi-linear analysis of the ion Weibel instability (IWI) for waves with parallel propagation is carried out for parameters appropriate to the earth's neutral sheet during the substorm interval. For ion drift speed reaching sizable fraction of the ion thermal speed, unstable waves grow to a nonlinear regime in a time interval greater than an ion gyroperiod. The saturation level is attained with current density reduced to about 15-28 percent of its preactivity level. The unstable wave amplitude normalized to the initial ambient field is found to be in the range of 0.2-0.8. This is accompanied by ion heating along the magnetic field with the parallel temperature being enhanced by 25-90 percent. Thus, the IWI can provide nonadiabatic heating of ions in current disruptions during substorms. The associated anomalous resistivity is estimated to be about 1 x 10 exp -7 to 1 x 10 exp -6 s, which is about 11 to 12 orders of magnitude above the classical resistivity.

  11. Influence of chain topology on polymer crystallization: poly(ethylene oxide) (PEO) rings vs. linear chains.

    PubMed

    Zardalidis, George; Mars, Julian; Allgaier, Jürgen; Mezger, Markus; Richter, Dieter; Floudas, George

    2016-10-04

    The absence of entanglements, the more compact structure and the faster diffusion in melts of cyclic poly(ethylene oxide) (PEO) chains have consequences on their crystallization behavior at the lamellar and spherulitic length scales. Rings with molecular weight below the entanglement molecular weight (M < Me), attain the equilibrium configuration composed from twice-folded chains with a lamellar periodicity that is half of the corresponding linear chains. Rings with M > Me undergo distinct step-like conformational changes to a crystalline lamellar with the equilibrium configuration. Rings melt from this configuration in the absence of crystal thickening in sharp contrast to linear chains. In general, rings more easily attain their extended equilibrium configuration due to strained segments and the absence of entanglements. In addition, rings have a higher equilibrium melting temperature. At the level of the spherulitic superstructure, growth rates are much faster for rings reflecting the faster diffusion and more compact structure. With respect to the segmental dynamics in their semi-crystalline state, ring PEOs with a steepness index of ∼34 form some of the "strongest" glasses.

  12. Effects of ferroelectric nanoparticles on ion transport in a liquid crystal

    NASA Astrophysics Data System (ADS)

    Basu, Rajratan; Garvey, Alfred

    2014-10-01

    A small quantity of BaTiO3 ferroelectric nanoparticles (FNPs) of 50 nm diameter was doped in a nematic liquid crystal (LC), and the free ion concentration was found to be significantly reduced in the LC + FNP hybrid compared to that of the pure LC. The strong electric fields, due to the permanent dipole moment of the FNPs, trapped some mobile ions, reducing the free ion concentration in the LC media. The reduction of free ions was found to have coherent impacts on the LC's conductivity, rotational viscosity, and electric field-induced nematic switching.

  13. Effects of ferroelectric nanoparticles on ion-transport in a liquid crystal

    NASA Astrophysics Data System (ADS)

    Garvey, Alfred; Basu, Rajratan

    2015-03-01

    A small quantity of BaTiO3 ferroelectric nanoparticles (FNPs) of 50 nm diameter was doped in a nematic liquid crystal (LC), and the free ion concentration was found to be significantly reduced in the LC +FNP hybrid compared to that of the pure LC. The strong electric fields, due to the permanent dipole moment of the FNPs, trapped some mobile ions, reducing the free ion concentration in the LC media. The reduction of free ions was found to have coherent impacts on the LC's conductivity, rotational viscosity, and electric field-induced nematic switching.

  14. 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.

  15. Crystal structure and magnetic properties of linear chain potassium aquotetrafluoromanganate(III)

    NASA Astrophysics Data System (ADS)

    Palacio, Fernando; Andres, Mercedes; Esteban-Calderon, C.; Martinez-Ripoll, M.; Garcia-Blanco, S.

    1988-09-01

    The crystal structure and single-crystal ac magnetic susceptibilities of KMnF 4·H 2O are reported. The structure, which is isomorphous to that of RbMnF 4·H 2O, consists of chains of alternating trans-[ MnF 4F {2}/{2}] 2- and trans-[ MnF 2F {2}/{2}( H 2O ) 2] tetragonally elongated octahedra connected to each other by shared apical fluorine atoms. Crystal data: Space group {C2}/{c}, a = 13.907(1) Å, b = 6.2136(2) Å, c = 10.492(1)Å, β = 104.69(1)°, V = 877.0(2) Å 3, Dc = 2.85 g cm -3, Z = 8, R = 0.044. Magnetic susceptibility measurements show a broad maximum around 52 K indicative of lower dimensionality behavior. The data may be fit to a Heisenberg S = 2 linear chain model with {J}/{k B} = -6.5 K and g = 2.05. At 8.45 K a sharp peak in the susceptibility data parallel to the chains indicates weak ferromagnetic behavior.

  16. Linear and nonlinear optical properties of terbium calcium oxyborate single crystals.

    PubMed

    Yuan, Dongsheng; Gao, Zeliang; Zhang, Shaojun; Jia, Zhitai; Shu, Jun; Li, Yang; Wang, Zhengping; Tao, Xutang

    2014-11-03

    The linear and nonlinear optical properties of TbCa4O(BO3)3 (abbreviated as TbCOB) single crystals were investigated for the first time. The refractive indices of TbCOB at several wavelengths were measured by using the minimum deviation method and the parameters of Sellmeier's dispersion equation were determined from the experimental data. The complete set of six second-order nonlinear optical (NLO) coefficients of TbCOB single crystals were obtained using the Maker fringe (FM) technique, with the largest d32 being on the order of 1.65 pm/V. Moreover, the phase-matching (PM) configurations of second-order harmonic generation (SHG) in the principal planes were calculated, and the largest effective NLO coefficient is deff = 0.86 pm/V along (22.56°, 180°) PM direction. The SHG conversion efficiency from 1064 nm to 532 nm of 8 mm long crystal samples without AR coating along this direction was achieved 57.1% at 28.2 mW input power, and it has a small walk-off angle of 13.8 mrad. In addition, the comparison and discussion with GdCOB and YCOB were carried out.

  17. 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

  18. Detection of ion micromotion in a linear Paul trap with a high finesse cavity.

    PubMed

    Chuah, Boon Leng; Lewty, Nicholas C; Cazan, Radu; Barrett, Murray D

    2013-05-06

    We demonstrate minimization of ion micromotion in a linear Paul trap with the use of a high finesse cavity. The excess ion micromotion projected along the optical cavity axis or along the laser propagation direction manifests itself as sideband peaks around the carrier in the ion-cavity emission spectrum. By minimizing the sideband height in the emission spectrum, we are able to reduce the micromotion amplitude along two directions to approximately the spread of the ground state wave function. This method is useful for cavity QED experiments as it describes the possibility of efficient 3-D micromotion compensation despite optical access limitations imposed by the cavity mirrors. We also show that, in principle, sub-nanometer micromotion compensation is achievable with our current system.

  19. 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.

  20. 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.

  1. Optical spectroscopy of random deformations in elastically-anisotropic crystals containing rare-earth ions

    NASA Astrophysics Data System (ADS)

    Malkin, B. Z.; Baibekov, E. I.; Abishev, N. M.; Pytalev, D. S.; Popova, M. N.; Bettinelli, M.

    2016-12-01

    We present the results of studies of spectral effects in the optical high-resolution (0.01 cm-1) spectra of rare-earth ions in crystals caused by random deformations of a crystal lattice. Low-temperature polarized transmission spectra in a broad spectral range (5000-15000 cm-1) were taken for tetragonal single crystals ABO4 (A=Y, Lu; B=V, P) containing impurity Tm3+ ions with concentrations 0.2 and 1.0 at.%. A specific fine structure of singlet-doublet transitions in the Tm3+ ions was observed. We demonstrate a possibility to estimate a concentration of intrinsic lattice defects from the analysis of the measurement data, by making use of an analytical expression derived in the present work for the distribution function of random lattice strains induced by point defects in the elastically-anisotropic continuum.

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

    PubMed Central

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

    2013-01-01

    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. PMID:23846531

  3. 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.

  4. Effects of low-fluence swift iodine ion bombardment on the crystallization of ion-beam-synthesized silicon carbide

    NASA Astrophysics Data System (ADS)

    Intarasiri, S.; Yu, L. D.; Singkarat, S.; Hallén, A.; Lu, J.; Ottosson, M.; Jensen, J.; Possnert, G.

    2007-04-01

    Ion beam synthesis using high-fluence carbon ion implantation in silicon in combination with subsequent or in situ thermal annealing has been shown to be able to form nanocrystalline cubic SiC (3C-SiC) layers in silicon. In this study, a silicon carbide layer was synthesized by 40-keV C12+ implantation of a p-type (100) Si wafer at a fluence of 6.5×1017 ions/cm2 at an elevated temperature. The existence of the implanted carbon in Si substrate was investigated by time-of-flight energy elastic recoil detection analysis. The SiC layer was subsequently irradiated by 10-30 MeV I127 ions to a very low fluence of 1012 ions/cm2 at temperatures from 80 to 800 °C to study the effect on the crystallization of the SiC layer. Infrared spectroscopy and Raman scattering measurement were used to monitor the formation of SiC and detailed information about the SiC film properties was obtained by analyzing the peak shape of the Si-C stretching mode absorption. The change in crystallinity of the synthesized layer was probed by glancing incidence x-ray diffraction measurement and transmission electron microscopy was also used to confirm the results and to model the crystallization process. The results from all these measurements showed in a coherent way that the synthesized structure was a polycrystalline layer with nanometer sized SiC crystals buried in a-Si matrix. The crystallinity of the SiC layer was enhanced by the low-fluence swift heavy ion bombardment and also favored by higher energy, higher fluence, and higher substrate temperature. It is suggested that electronic stopping plays a dominant role in the enhancement.

  5. 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

  6. 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

  7. Growth of potassium iodide single-crystals using ion track membranes as templates

    NASA Astrophysics Data System (ADS)

    Dobrev, D.; Vetter, J.; Neumann, R.

    1998-12-01

    A principle possibility is demonstrated to apply the ion track membranes as a template for the crystallization of inorganic salts. As an example, potassium iodide has been grown in a matrix of etched ion tracks produced in polycarbonate foils. Arrays of stable free-standing cylindrical microcolumns are observed after dissolution of the organic matrix. They represent single crystals oriented with their <1 0 0> or <1 1 0> crystallographic directions along the cylinder axes. Possible ways to govern their predominant orientations are briefly discussed.

  8. Novel Characterization Method of Ions in Liquid Crystal Materials by Complex Dielectric Constant Measurements

    NASA Astrophysics Data System (ADS)

    Sawada, Atsushi; Tarumi, Kazuaki; Naemura, Shohei

    1999-03-01

    The frequency dependence of the complex dielectric constant of liquid crystal materials doped with tetra-n-butylammonium iodide (TBAI) is investigated in the low-frequency region, and the experimental results are analyzed in terms of space charge polarization. The contribution from an electric double layer is also taken into consideration in the analysis. By means of curve fitting utilizing theoretical expressions of the space charge polarization, five sets of diffusion coefficient and density values are obtained for mobile ions. It is confirmed by experiments on the temperature dependence that five kinds of ions follow Walden's rule, and verified from the viewpoint of ion radii that two of the five kinds of ions are TBA+ and I-. The frequency-dependent dielectric properties, which are characteristic of the behaviors of ions, can be well explained by this study and the analytical method introduced here is considered to be powerful for the evaluation of the attributes of mobile ions.

  9. Interaction between crystal lattice and mobile ions in copper selenides studied by EXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Asylgushina, G. N.; Bikkulova, N. N.; Titova, S. G.; Kochubey, D. I.

    2005-05-01

    Interaction between crystal lattice and mobile Cu ions has been studied in Cu 2-xSe in superionic and in normal state using EXAFS-spectroscopy. It has been found that the transition from normal to superionic state and change of mobile Cu ion concentration practically do not have an influence on local state of Cu atoms, but change of both these parameters is accompanied by a change of Se-sublattice state.

  10. Enhanced performance of pulsed Q collision induced dissociation-based peptide identification on a dual-pressure linear ion trap.

    PubMed

    Lössner, Christopher; Blackstock, Walter; Gunaratne, Jayantha

    2012-01-01

    Pulsed Q collision induced dissociation (PQD) was introduced for isobaric tag quantification on linear ion traps to circumvent the problem of the low-mass cut-off for collision induced dissociation (CID). Unfortunately, fragmentation efficiency is compromised and PQD has found limited use for identification as well as quantification. We demonstrate that PQD has a comparable peptide identification performance to CID on dual-pressure linear ion traps, opening the potential for wider use of isobaric tag quantification on this new generation of linear ion traps.

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

    SciTech Connect

    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.

  12. A crystal structure study when crystallized only in d(CG)3 + methylamine and a d(CG)3 + metal ion.

    PubMed

    Ohishi, Hirofumi; Ishida, Toshimasa; Tsukamoto, Koji; Maezaki, Naoyoshi; Tanaka, Tetsuaki

    2006-01-01

    There is not an example of the crystallization only of d(CG)(3) and a metallic cation without putting the amine in addition in there is no example of the crystallization d(CG)(3) with methylamine that is the mono-amine so far either. We were able to obtain a very beautiful crystal with all sides of 0.3mm by the sitting drop method that had done the crystallization of d(CG)(3)+ methylamine and d(CG)(3)+ Mg(2 +). The crystal was diffracted up to 1.0 A by using the synchrotron radiation. As a result of the X-ray crystal structure analysis, methylamine was not seen while d(CG)(3)+ methylamine was crystallizing mysteriously. d(CG)(3) had stabilized with five Mg(2+) ions. d(CG)(3) had stabilized similarly with five Mg(2+) ions in the crystal of d(CG)(3)+ Mg(2+). The position of these five Mg(2+) ions understood that I agreed on superimpose in a crystal of d(CG)(3) + methylamine, a crystal of d(CG)(3)+Mg(2+), a crystal of d(CG)(3) + spermidine, and crystals of d(CG)(3) + PA (24) which was already analyzed so as to cut it and stabilized d(CG)(3) at an about the same position.

  13. Growth, spectral and crystallization perfection studies of semi organic non linear optical crystal - L-alanine lithium chloride

    NASA Astrophysics Data System (ADS)

    Redrothu, Hanumantharao; Kalainathan, S.; Bhagavannarayana, G.

    2012-06-01

    Single crystals of L-alanine lithium chloride single crystals were successfully grown using slow evaporation solution growth technique at constant temperature (303K). The formation of the new crystal has been confirmed by single-crystal X-ray diffraction, FT-IR studies. The crystalline perfection was analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. The powder second harmonic generation (SHG) has been confirmed by Nd: YAG laser. The results have been discussed in detail.

  14. 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.

  15. Middle-infrared luminescence of praseodymium ions in silver halide crystals and fibers.

    PubMed

    Nagli, Lev; Gayer, Ofer; Katzir, Abraham

    2005-07-15

    The luminescence of AgBr, AgCl, and AgClBr crystals and fibers doped with Pr3+ ions was investigated in the middle-infrared spectral range. We measured the absorption, emission, and kinetic parameters over a broad temperature range. Strong luminescence in the spectral range 4-5.5 microm was observed for the first time to our knowledge in silver halide crystals and fibers at room temperature. No noticeable differences were observed between the crystals and the fibers. We calculated various optical parameters for Pr:AgBr and Pr:AgCl crystals, using the Judd-Ofelt approximation. Both the measured results and the calculated parameters indicate that these doped crystals and fibers would be good candidates for the fabrication of mid-IR solid-state lasers or fiber lasers.

  16. Ion channeling study of lattice distortions in chromium-doped SrTiO3 crystals

    NASA Astrophysics Data System (ADS)

    Lavrentiev, V.; Vacik, J.; Dejneka, A.; Trepakov, V.; Jastrabik, L.

    2013-07-01

    The results of ion channeling studies of lattice distortions in SrTiO3: Cr single crystals are presented. Two types of single crystals containing the same amount of Cr impurities but differing in stoichiometry have been investigated. The single crystals grown by the Verneuil method have the compositions of standard-grown SrTiO3: Cr (0.05 at % Cr), whereas the single crystals grown with a strontium deficiency and a chromium compensating amount have the composition Sr0.9995TiO3 (0.05 at % Cr). Analysis of the angular channeling spectra indicates that, in crystals of both types, the main defects are Cr impurities located in octahedral sites. In the SrTiO3: Cr crystals, impurity atoms manifest themselves as Cr4+ with tetragonal Jahn-Teller distortions of the surrounding lattice. In the Sr0.9995TiO3: Cr crystals grown with a Sr deficiency, the characteristic displacements of Ti ions in the third coordination sphere of the Jahn-Teller center Cr4+ exhibit the effect of interaction of the center with a neighboring vacancy in the Sr sublattice.

  17. The effect of ferrocyanide ions on sodium chloride crystallization in salt mixtures

    NASA Astrophysics Data System (ADS)

    Gupta, Sonia; Pel, Leo; Steiger, Michael; Kopinga, Klaas

    2015-01-01

    The use of crystallization inhibitors has been proposed as a potential preventive treatment method against damage and is extensively tested for crystallization of single salts. However, in practice salt mixtures are present. Therefore, before using inhibitors in practice there is a strong need to explore their effect on salt mixtures. In this research, we studied the effect of ferrocyanide ions ([Fe(CN)6]4-) on NaCl crystallization in single salt and in salt mixtures of NaCl-KCl and NaCl-LiCl. A series of micro droplet drying experiments were undertaken. Time lapse microscopy of the crystallization was performed along with NMR measurements of hydrogen, sodium and lithium ions. This gives the possibility to visualize the drying of the droplet while simultaneously obtaining information of both NaCl and LiCl concentration in the droplet. For a NaCl solution droplet, in the presence of inhibitor, a significantly higher supersaturation prior to the onset of crystallization and a change in crystal morphology were observed. On the other hand, for salt mixtures, lower supersaturation compared to single salt and dendritic crystal morphology was seen in the presence of inhibitor. In a porous material, such a type of morphology can promote the formation of efflorescence that causes only little structural damage.

  18. Automated identification of elemental ions in macromolecular crystal structures

    SciTech Connect

    Echols, Nathaniel Morshed, Nader; Afonine, Pavel V.; McCoy, Airlie J.; Read, Randy J.; Terwilliger, Thomas C.; Adams, Paul D.

    2014-04-01

    The solvent-picking procedure in phenix.refine has been extended and combined with Phaser anomalous substructure completion and analysis of coordination geometry to identify and place elemental ions. Many macromolecular model-building and refinement programs can automatically place solvent atoms in electron density at moderate-to-high resolution. This process frequently builds water molecules in place of elemental ions, the identification of which must be performed manually. The solvent-picking algorithms in phenix.refine have been extended to build common ions based on an analysis of the chemical environment as well as physical properties such as occupancy, B factor and anomalous scattering. The method is most effective for heavier elements such as calcium and zinc, for which a majority of sites can be placed with few false positives in a diverse test set of structures. At atomic resolution, it is observed that it can also be possible to identify tightly bound sodium and magnesium ions. A number of challenges that contribute to the difficulty of completely automating the process of structure completion are discussed.

  19. 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.

  20. 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.

  1. Design and fabrication of ytterbium-doped photonic crystal fiber with low non-linearity

    NASA Astrophysics Data System (ADS)

    Wu, Jiale; Zhang, Wei; Zhou, Guiyao; Xia, Changming; Liu, Jiantao; Zheng, Yan; Tian, Hongchun; Hou, Zhiyun

    2015-05-01

    We report on an ytterbium-doped photonic crystal fiber fabricated by laser sintering technology combined with a solution doping method. This novel fabrication process has never been reported to the best of our knowledge. Together with low non-linearity, this PCF combines the advantages of high pump absorption efficiency and bend-insensitive, which makes this fiber predestinated for the high power fiber laser applications. The fiber laser experiment was conducted with a simple Fabry-Perot cavity to verify the performance of the PCF. A high slope efficiency of ~70.6% was obtained from a 1.5 m-long fiber. During the experiment, no roll over was observed up to the highest power level, which was only limited by the available pump power. The experimental results reveal the enormous output power scaling potential of the PCF.

  2. 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

  3. Linear parabolic single-crystal diamond refractive lenses for synchrotron X-ray sources.

    PubMed

    Terentyev, Sergey; Polikarpov, Maxim; Snigireva, Irina; Di Michiel, Marco; Zholudev, Sergey; Yunkin, Vyacheslav; Kuznetsov, Sergey; Blank, Vladimir; Snigirev, Anatoly

    2017-01-01

    Linear parabolic diamond refractive lenses are presented, designed to withstand high thermal and radiation loads coming from upgraded accelerator X-ray sources. Lenses were manufactured by picosecond laser treatment of a high-quality single-crystal synthetic diamond. Twelve lenses with radius of curvature at parabola apex R = 200 µm, geometrical aperture A = 900 µm and length L = 1.5 mm were stacked as a compound refractive lens and tested at the ESRF ID06 beamline. A focal spot of size 2.2 µm and a gain of 20 were measured at 8 keV. The lens profile and surface quality were estimated by grating interferometry and X-ray radiography. In addition, the influence of X-ray glitches on the focusing properties of the compound refractive lens were studied.

  4. 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.

  5. Non-linear electro-optical effects in the study of the helical smectic liquid crystals

    NASA Astrophysics Data System (ADS)

    Nowicka, K.; Kuczyński, W.

    2016-04-01

    Measurements of the non-linear electro-optical effects for the well-known prototype liquid crystal material (MHPOBC) are presented. The method to identify liquid crystalline phases and to determine temperatures of phase transitions based on the analysis of the second harmonic component of electro-optical response spectra is used. Applying that method, the values of the frequency (?) at which the second harmonic electro-optic response (EOR) possesses an extremum are determined for each smectic phase. We suggest that this characteristic frequency correspond to the phase-type mode processes. Furthermore, we show that the usually neglected results on heating can be useful in discussions of dynamical behaviour of second harmonic EOR in case of smectic phases.

  6. Investigation of the linear and second-order nonlinear optical properties of molecular crystals within the local field theory.

    PubMed

    Seidler, Tomasz; Stadnicka, Katarzyna; Champagne, Benoît

    2013-09-21

    In this paper it is shown that modest calculations combining first principles evaluations of the molecular properties with electrostatic interaction schemes to account for the crystal environment effects are reliable for predicting and interpreting the experimentally measured electric linear and second-order nonlinear optical susceptibilities of molecular crystals within the experimental error bars. This is illustrated by considering two molecular crystals, namely: 2-methyl-4-nitroaniline and 4-(N,N-dimethylamino)-3-acetamidonitrobenzene. Three types of surrounding effects should be accounted for (i) the polarization due to the surrounding molecules, described here by static electric fields originating from their electric dipoles or charge distributions, (ii) the intermolecular interactions, which affect the geometry and particularly the molecular conformation, and (iii) the screening of the external electric field by the constitutive molecules. This study further highlights the role of electron correlation on the linear and nonlinear responses of molecular crystals and the challenge of describing frequency dispersion.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Top-down protein fragmentation by infrared multiphoton dissociation in a dual pressure linear ion trap.

    PubMed

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

    2009-11-01

    Infrared multiphoton dissociation (IRMPD) was implemented in a novel dual pressure linear ion trap for rapid top-down proteomics. The high pressure cell provided improved trapping and isolation efficiencies while the isotopic profiles of 10+ charged ions could be resolved by mass analysis in the low pressure cell that enabled effective top down protein identification. Striking differences between IRMPD in the low pressure cell and CID in the high pressure cell were observed for proteins ranging from 8.6 to 29 kDa. Because of secondary dissociation, IRMPD yielded product ions in significantly lower charge states as compared to CID, thus facilitating more accurate mass identification and streamlining product ion assignment. This outcome was especially useful for database searching of larger proteins (approximately 29 kDa) as IRMPD substantially improved protein identification and scoring confidence. Also, IRMPD showed an increased selectivity toward backbone cleavages N-terminal to proline and C-terminal to acidic residues (especially for the lowest charge states), which could be useful for a priori spectral predictions and enhanced database searching for protein identification.

  12. 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.

  13. A Miniaturized Linear Wire Ion Trap with Electron Ionization and Single Photon Ionization Sources

    NASA Astrophysics Data System (ADS)

    Wu, Qinghao; Tian, Yuan; Li, Ailin; Andrews, Derek; Hawkins, Aaron R.; Austin, Daniel E.

    2017-01-01

    A linear wire ion trap (LWIT) with both electron ionization (EI) and single photon ionization (SPI) sources was built. The SPI was provided by a vacuum ultraviolet (VUV) lamp with the ability to softly ionize organic compounds. The VUV lamp was driven by a pulse amplifier, which was controlled by a pulse generator, to avoid the detection of photons during ion detection. Sample gas was introduced through a leak valve, and the pressure in the system is shown to affect the signal-to-noise ratio and resolving power. Under optimized conditions, the limit of detection (LOD) for benzene was 80 ppbv using SPI, better than the LOD using EI (137 ppbv). System performance was demonstrated by distinguishing compounds in different classes from gasoline.

  14. Propagation and linear mode conversion of magnetosonic and electromagnetic ion cyclotron waves in the radiation belts

    NASA Astrophysics Data System (ADS)

    Horne, Richard B.; Miyoshi, Yoshizumi

    2016-10-01

    Magnetosonic waves and electromagnetic ion cyclotron (EMIC) waves are important for electron acceleration and loss from the radiation belts. It is generally understood that these waves are generated by unstable ion distributions that form during geomagnetically disturbed times. Here we show that magnetosonic waves could be a source of EMIC waves as a result of propagation and a process of linear mode conversion. The converse is also possible. We present ray tracing to show how magnetosonic (EMIC) waves launched with large (small) wave normal angles can reach a location where the wave normal angle is zero and the wave frequency equals the so-called crossover frequency whereupon energy can be converted from one mode to another without attenuation. While EMIC waves could be a source of magnetosonic waves below the crossover frequency, magnetosonic waves could be a source of hydrogen band waves but not helium band waves.

  15. Non-linear state transitions in neural systems: from ion to networks

    NASA Astrophysics Data System (ADS)

    Liljenström, Hans; Braun, Hans; Århem, Peter

    2001-03-01

    The activity of neural systems often seems to depend on non-linear threshold effects, where microscopic fluctuations may cause rapid and large effects at a macroscopic level. Single ion channels are found to be capable of eliciting action potentials in small hippocampal interneurons. Computer simulations show that spontaneous neuronal activity can induce global oscillations in networks of neurons. For a small change in some parameter values, the global activity instead becomes chaotic-like. We use experimental as well as computational methods to investigate mechanisms by which neural systems can amplify weak signals and control the system at a larger scale. We also investigate if there are non-random processes in ion channel kinetics and use topological methods for the analysis, also of computer simulations.

  16. Synthesis of guanidinium-sulfonimide ion pairs: towards novel ionic liquid crystals.

    PubMed

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

    2013-01-01

    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.

  17. Quantum quenches of ion Coulomb crystals across structural instabilities. II. Thermal effects

    NASA Astrophysics Data System (ADS)

    Baltrusch, Jens D.; Cormick, Cecilia; Morigi, Giovanna

    2013-03-01

    We theoretically analyze the efficiency of a protocol for creating mesoscopic superpositions of ion chains, described in Baltrusch [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.84.063821 84, 063821 (2011)], as a function of the temperature of the crystal. The protocol makes use of state-dependent forces, so that a coherent superposition of the electronic states of one ion evolves into an entangled state between the chain's internal and external degrees of freedom. Ion Coulomb crystals are well isolated from the external environment and should therefore experience a coherent, unitary evolution, which follows the quench and generates structural Schrödinger-cat-like states. The temperature of the chain, however, introduces a statistical uncertainty in the final state. We characterize the quantum state of the crystal by means of the visibility of Ramsey interferometry performed on one ion of the chain and determine its decay as a function of the crystal's initial temperature. This analysis allows one to determine the conditions on the chain's initial state in order to efficiently perform the protocol.

  18. 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.

  19. Time-Resolved Imaging of the MALDI Linear-TOF Ion Cloud: Direct Visualization and Exploitation of Ion Optical Phenomena Using a Position- and Time-Sensitive Detector

    NASA Astrophysics Data System (ADS)

    Ellis, Shane R.; Soltwisch, Jens; Heeren, Ron M. A.

    2014-05-01

    In this study, we describe the implementation of a position- and time-sensitive detection system (Timepix detector) to directly visualize the spatial distributions of the matrix-assisted laser desorption ionization ion cloud in a linear-time-of-flight (MALDI linear-ToF) as it is projected onto the detector surface. These time-resolved images allow direct visualization of m/z-dependent ion focusing effects that occur within the ion source of the instrument. The influence of key parameters, namely extraction voltage ( E V ), pulsed-ion extraction (PIE) delay, and even the matrix-dependent initial ion velocity was investigated and were found to alter the focusing properties of the ion-optical system. Under certain conditions where the spatial focal plane coincides with the detector plane, so-called x-y space focusing could be observed (i.e., the focusing of the ion cloud to a small, well-defined spot on the detector). Such conditions allow for the stigmatic ion imaging of intact proteins for the first time on a commercial linear ToF-MS system. In combination with the ion-optical magnification of the system (~100×), a spatial resolving power of 11-16 μm with a pixel size of 550 nm was recorded within a laser spot diameter of ~125 μm. This study demonstrates both the diagnostic and analytical advantages offered by the Timepix detector in ToF-MS.

  20. Anisotropic magnetotransport and exotic longitudinal linear magnetoresistance in WTe2 crystals

    DOE PAGES

    Zhao, Yanfei; Liu, Haiwen; Yan, Jiaqiang; ...

    2015-07-06

    Recently, the WTe2 semimetal, as a typical layered transition-metal dichalcogenide, attracted much attention due to an extremely large, non-saturating parabolic magnetoresistance in the perpendicular field. Here, we report a systematic study of the angular dependence of the magnetoresistance in a WTe2 single crystal. The significant anisotropic magnetotransport behavior in different magnetic field directions and violation of the Kohler's rule are observed. Unexpectedly, when the applied field and excitation current are both parallel to the tungsten chains of WTe2, an exotic large longitudinal linear magnetoresistance as high as 1200% at 15T and 2K is identified. These results imply that the WTe2more » semimetal, due to its balanced hole and electron populations, seems to be the first material for which a large longitudinal linear magnetoresistance appears when the external magnetic field is parallel to the applied current. Finally, our work may stimulate studies of double-carrier correlated materials and the corresponding quantum physics.« less

  1. Anisotropic magnetotransport and exotic longitudinal linear magnetoresistance in WTe2 crystals

    SciTech Connect

    Zhao, Yanfei; Liu, Haiwen; Yan, Jiaqiang; An, Wei; Liu, Jun; Zhang, Xi; Wang, Huichao; Liu, Yi; Jiang, Hua; Li, Qing; Wang, Yong; Li, Xin-Zheng; Mandrus, David; Xie, X. C.; Pan, Minghu; Wang, Jian

    2015-07-06

    Recently, the WTe2 semimetal, as a typical layered transition-metal dichalcogenide, attracted much attention due to an extremely large, non-saturating parabolic magnetoresistance in the perpendicular field. Here, we report a systematic study of the angular dependence of the magnetoresistance in a WTe2 single crystal. The significant anisotropic magnetotransport behavior in different magnetic field directions and violation of the Kohler's rule are observed. Unexpectedly, when the applied field and excitation current are both parallel to the tungsten chains of WTe2, an exotic large longitudinal linear magnetoresistance as high as 1200% at 15T and 2K is identified. These results imply that the WTe2 semimetal, due to its balanced hole and electron populations, seems to be the first material for which a large longitudinal linear magnetoresistance appears when the external magnetic field is parallel to the applied current. Finally, our work may stimulate studies of double-carrier correlated materials and the corresponding quantum physics.

  2. 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.

  3. How (non-)linear is the hydrodynamics of heavy ion collisions?

    NASA Astrophysics Data System (ADS)

    Floerchinger, Stefan; Wiedemann, Urs Achim; Beraudo, Andrea; Del Zanna, Luca; Inghirami, Gabriele; Rolando, Valentina

    2014-07-01

    We provide evidence from full numerical solutions that the hydrodynamical evolution of initial density fluctuations in heavy ion collisions can be understood order-by-order in a perturbative series in deviations from a smooth and azimuthally symmetric background solution. To leading linear order, modes with different azimuthal wave numbers do not mix. When quadratic and higher order corrections are numerically sizable, they can be understood as overtones with corresponding wave numbers in a perturbative series. Several findings reported in the recent literature result naturally from the general perturbative series formulated here.

  4. 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.

  5. Electron Transfer Governed Crystal Transformation of Tungsten Trioxide upon Li Ions Intercalation

    SciTech Connect

    Wang, Zhiguo; He, Yang; Gu, Meng; Du, Yingge; Mao, Scott X.; Wang, Chongmin

    2016-09-21

    Reversible insertion/extraction of ions into a host lattice constitutes the fundamental operating principle of rechargeable battery and electrochromic materials. It is far more commonly observed that insertion of ions into a host lattice can lead to structural evolution of the host lattice, and for the most cases such a lattice evolution is subtle. However, it has never been clear as what kind of factors to control such a lattice structural evolution. Based on tungsten trioxide (WO3) model crystal, we use in situ transmission electron microscopy (TEM) and first principles calculation to explore the nature of Li ions intercalation induced crystal symmetry evolution of WO3. We discovered that Li insertion into the octahedral cavity of WO3 lattice will lead to a low to high symmetry transition, featuring a sequential monoclinic→tetragonal→cubic phase transition. The first principle calculation reveals that the phase transition is essentially governed by the electron transfer from Li to the WO6 octahedrons, which effectively leads to the weakening the W-O bond and modifying system band structure, resulting in an insulator to metal transition. The observation of the electronic effect on crystal symmetry and conductivity is significant, providing deep insights on the intercalation reactions in secondary rechargeable ion batteries and the approach for tailoring the functionalities of material based on insertion of ions in the lattice.

  6. 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.

  7. Imaging crystal spectrometer for high-resolution x-ray measurements on electron beam ion traps and tokamaks

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, P.; Magee, E. W.; Hell, N.; Brown, G. V.

    2016-11-01

    We describe a crystal spectrometer implemented on the Livermore electron beam ion traps that employ two spherically bent quartz crystals and a cryogenically cooled back-illuminated charge-coupled device detector to measure x rays with a nominal resolving power of λ/Δλ ≥ 10 000. Its focusing properties allow us to record x rays either with the plane of dispersion perpendicular or parallel to the electron beam and, thus, to preferentially select one of the two linear x-ray polarization components. Moreover, by choice of dispersion plane and focussing conditions, we use the instrument either to image the distribution of the ions within the 2 cm long trap region, or to concentrate x rays of a given energy to a point on the detector, which optimizes the signal-to-noise ratio. We demonstrate the operation and utility of the new instrument by presenting spectra of Mo34+, which prepares the instrument for use as a core impurity diagnostic on the NSTX-U spherical torus and other magnetic fusion devices that employ molybdenum as plasma facing components.

  8. Imaging crystal spectrometer for high-resolution x-ray measurements on electron beam ion traps and tokamaks.

    PubMed

    Beiersdorfer, P; Magee, E W; Hell, N; Brown, G V

    2016-11-01

    We describe a crystal spectrometer implemented on the Livermore electron beam ion traps that employ two spherically bent quartz crystals and a cryogenically cooled back-illuminated charge-coupled device detector to measure x rays with a nominal resolving power of λ/Δλ ≥ 10 000. Its focusing properties allow us to record x rays either with the plane of dispersion perpendicular or parallel to the electron beam and, thus, to preferentially select one of the two linear x-ray polarization components. Moreover, by choice of dispersion plane and focussing conditions, we use the instrument either to image the distribution of the ions within the 2 cm long trap region, or to concentrate x rays of a given energy to a point on the detector, which optimizes the signal-to-noise ratio. We demonstrate the operation and utility of the new instrument by presenting spectra of Mo(34+), which prepares the instrument for use as a core impurity diagnostic on the NSTX-U spherical torus and other magnetic fusion devices that employ molybdenum as plasma facing components.

  9. Effect of trace lanthanum ion on dissolution and crystal growth of calcium carbonate

    NASA Astrophysics Data System (ADS)

    Kamiya, Natsumi; Kagi, Hiroyuki; Tsunomori, Fumiaki; Tsuno, Hiroshi; Notsu, Kenji

    2004-07-01

    Impurity effects of trace lanthanum ion (La 3+) on the dissolution and growth of calcium carbonate were studied with in situ observation techniques. Dissolution kinetics of two polymorphs of calcium carbonate, calcite and vaterite, were investigated by monitoring the pH in the solution with laser-induced fluorescence spectroscopy using a pH-sensitive reagent, seminaphthorhodafluors. No effect on dissolution of vaterite was observed with the spectroscopic observations, whereas calcite dissolution was significantly inhibited by lanthanum ion with concentrations higher than 1 μM. Crystal growth and dissolution processes of calcite under the lanthanum-doped condition were observed by means of atomic force microscopy. Step propagations during crystal growth and dissolution of calcite were inhibited by trace lanthanum ion (5 μM). An insoluble thin layer of lanthanum carbonate deposited on the step site of the calcite surface could be a possible cause of the inhibitions observed both for dissolution and growth.

  10. EPR and optical absorption studies on Gd 3+ ions in ammonium hydrogen malonate single crystals

    NASA Astrophysics Data System (ADS)

    Kripal, Ram; Mishra, Indrajeet

    2010-01-01

    X-Band electron paramagnetic resonance (EPR) studies of Gd 3+ ions in ammonium hydrogen malonate single crystals have been done at room temperature. Detailed EPR analysis indicates the presence of four physically equivalent but magnetically inequivalent sites. The zero-field splitting parameters and g factor are determined. The Gd 3+ ion is in 8S state; its levels are split by the action of the crystalline electric field of monoclinic symmetry. The optical absorption spectra of Gd 3+ ions in single crystals of ammonium hydrogen malonate are also recorded at room temperature. The energy levels of the 4f 7 configuration are calculated and compared with those observed experimentally. The values of E1=5854±11, E2=31±0.36, E3=592±3.3 and ζ 4f=1595±25 cm -1 are found to give the best over-all agreement between experimentally observed and calculated levels.

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

    PubMed

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

    2016-04-06

    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.

  12. 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.

  13. Electrical conductivity of MgO crystals implanted with lithium ions

    NASA Astrophysics Data System (ADS)

    Tardío, M.; Ramírez, R.; González, R.; Chen, Y.; Alves, E.

    2002-05-01

    MgO single crystals were implanted with a fluence of 1×10 17 Li +/cm 2 with 175 keV. Using ac and dc techniques, the electrical conductivity of these crystals was investigated in the temperature range 296-440 K. The electrical conductivity of the implanted region was 14 orders of magnitude higher than the unimplanted area. Measurements at different temperatures suggest a thermally activated process with an activation energy of about 0.33 eV. In the implanted area, electrical contacts are found to be ohmic whereas contacts are blocking in unimplanted crystals. Removal of thin layers of the implanted region by immersing the crystal in hot phosphoric acid suggests that the enhancement in conductivity in the implanted region is associated with the intrinsic defects created by the implantation, rather than with the Li ions.

  14. 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.

  15. Crystal growth, perfection, linear and nonlinear optical, photoconductivity, dielectric, thermal and laser damage threshold properties of 4-methylimidazolium picrate: an interesting organic crystal for photonic and optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Rajesh, K.; Arun, A.; Mani, A.; Praveen Kumar, P.

    2016-10-01

    The 4-methylimidazolium picrate has been synthesized and characterized successfully. Single and powder x-ray diffraction studies were conducted which confirmed the crystal structure, and the value of the strain was calculated. The crystal perfection was determined by a HRXR diffractometer. The transmission spectrum exhibited a better transmittance of the crystal in the entire visible region with a lower cut-off wavelength of 209 nm. The linear absorption value was calculated by the optical limiting method. A birefringence study was also carried out. Second and third order nonlinear optical properties of the crystal were found by second harmonic generation and the z-scan technique. The crystals were also characterized by dielectric measurement and a photoconductivity analyzer to determine the dielectric property and the optical conductivity of the crystal. The laser damage threshold activity of the grown crystal was studied by a Q-switched Nd:YAG laser beam. Thermal studies established that the compound did not undergo a phase transition and was stable up to 240 °C.

  16. 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

  17. Comparison of Monte-Carlo Ion Cyclotron Heating Model with Full-Wave Linear Absorption Model

    NASA Astrophysics Data System (ADS)

    Choi, M.; Chan, V. S.; Berry, L. A.; Jaeger, E. F.; Green, D.; Bonoli, P.; Wright, J.

    2009-05-01

    To fully account for the wave-particle interaction physics in ion-cyclotron resonant frequency heating experiments, the 5-D Monte-Carlo code ORBIT-RF is being coupled with the 2-D full wave code AORSA to iteratively evolve ion distribution in x-v space that is used to update the dielectric tensor in AORSA for evaluating the full-wave fields. It is demonstrated that using the full-wave fields from a Maxwellian dielectric tensor in AORSA and confining the resonant ions to their initial orbits in ORBIT-RF, ORBIT-RF largely reproduces the AORSA linear wave absorption profiles for fundamental and higher harmonic ICRF heating. An exception is an observed inward shift of the ORBIT-RF absorption peak for high harmonics near the magnetic-axis compared with that of AORSA, which can be attributed to a finite orbit width effect. Analysis of power absorption in velocity space confirms that significant power is absorbed by energetic particles with their banana tips at resonance locations.

  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. 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.

  20. 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.

  1. 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.

  2. The effect of CuII ions in L-asparagine single crystals

    NASA Astrophysics Data System (ADS)

    Santana, Ricardo C.; Gontijo, Henrique O.; Menezes, Arthur F.; Martins, José A.; Carvalho, Jesiel F.

    2016-11-01

    We report the synthesis, crystal growth, and spectroscopic characterization of L-asparagine monohydrate (LAM) single crystals doped with CuII. The crystals were successfully grown by slow cooling from a supersaturated aqueous solution up to size of 16×12×2 mm3;the effect of copper impurities in the crystals morphology was discussed. Electron Paramagnetic Resonance (EPR) was used to calculate the g and hyperfine coupling (A) tensors of the CuII ions (g1=2.044, g2=2.105, g3=2.383and A1≈0, A2=35, A3=108 Gauss). The EPR spectra for certain orientations of the magnetic field suggest that CuII ions are coordinated to two 14N atoms. Correlating the EPR and optical absorption results, the crystal field and the CuII orbital bond parameters were calculated. The results indicate that the paramagnetic center occupies interstitial rhombic distorted site and the ground orbital state for the unpaired electron is the d(x2-y2).

  3. Noninvasive technique for studying plasma modes of ion Coulomb crystals using cavity quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Drewsen, Michael

    2009-11-01

    Cavity Quantum ElectroDynamics (CQED) is a research field which focuses on understanding the interactions between matter and the electromagnetic field in cavities at the quantum level. Currently, CQED is a very active research field due to the prospect of creating efficient light-matter quantum interfaces at the single photon level for quantum information science. Ion Coulomb crystals have a series of properties of particular interest for CQED studies, as demonstrated in recent CQED experiments [1]. The coupling strength between ions in the crystals and photons in the cavity strongly depend on the motion of the ions due to the Doppler-effect. Consequently, the CQED signals can be exploited to learn about excitations of plasma modes in ion Coulomb crystals. Since the method relies on having one or less photons in the cavity at any time, it constitutes a noninvasive alternative to the Doppler-fluorescence method previous demonstrated in Penning trap experiments [2]. So far, CQED signal has been used to characterize how several normal mode frequencies depend on the aspect ratio of Coulomb crystals, and how the so-called micromotion of ions confined in rf traps influences the damping of the mode [3]. The observed mode frequencies are in remarkable agreement with theoretical prediction based on uniformly charged fluids [4]. [4pt] [1] P. F. Herskind, A. Dantan, J. P. Marler, M. Albert, and M. Drewsen, to appear in Nature Physics (2009). [0pt] [2] T. B. Mitchell, J. J. Bollinger, X.-P. Huang, and W. M. Itano, Opt. Express 2, 314 (1998). [0pt] [3] J. P. Marler, M. Albert, D. Guenot, P. F. Herskind, A. Dantan and M. Drewsen, manuscript in preparation. [0pt] [4] D. H. E. Dubin, Phys. Rev. Lett. 66, 2076 (1991).

  4. 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

    2014-04-11

    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.

  5. Silver Ion Polyelectrolyte Container as a Sensitive Quartz Crystal Microbalance Gas Detector.

    PubMed

    Tsuge, Yosuke; Moriyama, Yukari; Tokura, Yuki; Shiratori, Seimei

    2016-11-01

    A polyelectrolyte film containing metastable silver ions was applied as a quartz crystal microbalance (QCM) gas detector. The polyelectrolyte film was obtained by immersing a polyelectrolyte with numerous amine groups in a metal ion solution. The QCM detector with silver ions responded to a very low methylmercaptan gas concentration (20 ppb) but did not respond to ammonia, volatile amines, aromatic compounds, or alcohols. The response speed of the QCM detector increased gradually with increasing methylmercaptan concentrations. The highly sensitive and selective response is promoted by a ligand substitution reaction caused by the formation of coordinative bonds between a metastable silver ion and amine groups in the polyelectrolyte film. To the best of our knowledge, this system has the highest sensitivity among reported QCM gas detectors. Such high-sensitivity among reported QCM gas detectors. Such high-sensitivity gas detectors for volatile sulfur compounds have wide ranging applications in areas such as volcanic eruption prediction, food inspection, environmental analysis, and medical diagnostics.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2003-08-01

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

  9. 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.

  10. Impurities in noncubic crystals: stabilization mechanisms for Jahn-Teller ions in layered perovskites.

    PubMed

    García-Lastra, J M; Aramburu, J A; Barriuso, M T; Moreno, M

    2004-11-26

    Mechanisms responsible for the local geometry around Jahn-Teller impurities in K2NiF4 type lattices are shown to be different from those generating the warping in cubic crystals. The present density functional theory calculations reveal that the elastic anisotropy of the host lattice (visible for closed shell impurities) and the electric field created by the rest of lattice ions upon active electrons make it possible to have d(9) ions in an elongated geometry but with a A(1g) ground state. The puzzling difference between equilibrium geometries for Cu2+ and Ni+ in layered perovskites can reasonably be understood.

  11. Production yield of rare-earth ions implanted into an optical crystal

    SciTech Connect

    Kornher, Thomas Xia, Kangwei; Kolesov, Roman; Reuter, Rolf; Villa, Bruno; Wrachtrup, Jörg; Kukharchyk, Nadezhda; Wieck, Andreas D.; Siyushev, Petr; Stöhr, Rainer; Schreck, Matthias; Becker, Hans-Werner

    2016-02-01

    Rare-earth (RE) ions doped into desired locations of optical crystals might enable a range of novel integrated photonic devices for quantum applications. With this aim, we have investigated the production yield of cerium and praseodymium by means of ion implantation. As a measure, the collected fluorescence intensity from both implanted samples and single centers was used. With a tailored annealing procedure for cerium, a yield up to 53% was estimated. Praseodymium yield amounts up to 91%. Such high implantation yield indicates a feasibility of creation of nanopatterned rare-earth doping and suggests strong potential of RE species for on-chip photonic devices.

  12. 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.

  13. Linkage determination of linear oligosaccharides by MS(n) (n > 2) collision-induced dissociation of Z₁ ions in the negative ion mode.

    PubMed

    Konda, Chiharu; Bendiak, Brad; Xia, Yu

    2014-02-01

    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 (MS(n), n >2) and collision-induced dissociation (CID) of Z1 ions in the negative ion mode. Under low energy CID conditions, disaccharides (18)O-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. MS(3) 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 MS(n) 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.

  14. 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.

  15. 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.

  16. Crystal growth and spectroscopic properties of Er3+ ions doped CdF2 single crystals

    NASA Astrophysics Data System (ADS)

    Djellab, S.; Diaf, M.; Labbaci, K.; Guerbous, L.

    2014-04-01

    Single crystals of Er3+:CdF2 with good optical quality were grown by a Bridgman technique after purification of the starting materials. Absorption and emission spectra are recorded at room temperature. The Judd-Ofelt (JO) analysis was applied to obtain the three phenomenological intensity parameters and the transition strengths. These JO parameters are used to calculate the radiative transition probabilities, the radiation lifetimes and the branching ratios. The results obtained are in good agreement with those of other fluoride laser materials. We also carried out luminescence measurements for red and green emission. The studied host may offer infrared and visible laser emissions.

  17. Erbium ion implantation into diamond - measurement and modelling of the crystal structure.

    PubMed

    Cajzl, Jakub; Nekvindová, Pavla; Macková, Anna; Malinský, Petr; Sedmidubský, David; Hušák, Michal; Remeš, Zdeněk; Varga, Marián; Kromka, Alexander; Böttger, Roman; Oswald, Jiří

    2017-02-22

    Diamond is proposed as an extraordinary material usable in interdisciplinary fields, especially in optics and photonics. In this contribution we focus on the doping of diamond with erbium as an optically active centre. In the theoretical part of the study based on DFT simulations we have developed two Er-doped diamond structural models with 0 to 4 carbon vacancies in the vicinity of the Er atom and performed geometry optimizations by the calculation of cohesive energies and defect formation energies. The theoretical results showed an excellent agreement between the calculated and experimental cohesive energies for the parent diamond. The highest values of cohesive energies and the lowest values of defect formation energies were obtained for models with erbium in the substitutional carbon position with 1 or 3 vacancies in the vicinity of the erbium atom. From the geometry optimization the structural model with 1 vacancy had an octahedral symmetry whereas the model with 3 vacancies had a coordination of 10 forming a trigonal structure with a hexagonal ring. In the experimental part, erbium doped diamond crystal samples were prepared by ion implantation of Er(+) ions using ion implantation fluences ranging from 1 × 10(14) ions per cm(2) to 5 × 10(15) ions per cm(2). The experimental results revealed a high degree of diamond structural damage after the ion implantation process reaching up to 69% of disordered atoms in the samples. The prepared Er-doped diamond samples annealed at the temperatures of 400, 600 and 800 °C in a vacuum revealed clear luminescence, where the 〈110〉 cut sample has approximately 6-7 times higher luminescence intensity than the 〈001〉 cut sample with the same ion implantation fluence. The reported results are the first demonstration of the Er luminescence in the single crystal diamond structure for the near-infrared spectral region.

  18. Immobilization of bovine serum albumin as a sensitive biosensor for the detection of trace lead ion in solution by piezoelectric quartz crystal impedance.

    PubMed

    Yin, Jian; Wei, Wanzhi; Liu, Xiaoying; Kong, Bo; Wu, Ling; Gong, Shuguo

    2007-01-01

    A biosensor based on bovine serum albumin (BSA) for the detection of lead (Pb(2+)) ion was developed and characterized. BSA was immobilized onto a colloidal Au-modified piezoelectric quartz crystal (PQC) as a biosensor for the detection of Pb(2+) ion by piezoelectric quartz crystal impedance (PQCI). Calibration curves for the quantification of Pb(2+) ion showed excellent linearity throughout the concentration range from 1.0 x 10(-7) to 3.0 x 10(-9)mol/L. The interaction between the Pb(2+) ions and the sensor chip is influenced significantly by the pH of the reaction buffer, and the optimal pH for the experiment was 5.4. Under the optimal conditions, the detection limit of 1.0 x 10(-9)mol/L for Pb(2+) was obtained. Kinetic parameters of the Pb(2+)-BSA interactions were also determined by using this chip. The sensor chip could be regenerated for use by dipping in the ethylenediaminetetraacetic acid (EDTA) solution for approximately 2h, and the chip was used to detect Pb(2+) ion for eight times without obvious signal attenuation.

  19. Revelation of endogenously bound Fe(2+) ions in the crystal structure of ferritin from Escherichia coli.

    PubMed

    Thiruselvam, Viswanathan; Sivaraman, Padavattan; Kumarevel, Thirumananseri; Ponnuswamy, Mondikalipudur Nanjappagounder

    2014-10-24

    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 2.5Å. 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. Design of rare-earth-ion doped chalcogenide photonic crystals for enhancing the fluorescence emission

    NASA Astrophysics Data System (ADS)

    Zhang, Peiqing; Dai, Shixun; Niu, Xueke; Xu, Yinsheng; Zhang, Wei; Wu, Yuehao; Xu, Tiefeng; Nie, Qiuhua

    2014-07-01

    Rare-earth-ion doped chalcogenide glass is a promising material for developing mid-infrared light sources. In this work, Tm3+-doped chalcogenide glass was prepared and photonic crystal structures were designed to enhance its fluorescence emission at approximately 3.8 μm. By employing the finite-difference time-domain (FDTD) simulation, the emission characteristics of the luminescent centers in the bulk material and in the photonic crystals were worked out. Utilizing analysis of the photon excitation inside the sample and the photon extraction on the sample surface, it was found that fluorescence emission can be significantly enhanced 260-fold with the designed photonic crystal structure. The results of this work can be used to realize high-efficiency mid-infrared light sources.

  1. Interaction of Er{sup 3+} ions in Er-doped calcium - niobium - gallium garnet crystals

    SciTech Connect

    Malov, A V; Popov, A V; Ryabochkina, P A; Bol'shakov, E V

    2010-08-03

    The processes of nonradiative energy transfer in calcium - niobium - gallium garnet (CNGG) crystals doped with Er{sup 3+} ions are studied. It is found that the energy of erbium ions in the Er:CNGG crystal with the erbium atomic concentrations C{sub Er}=6% and 11% is transferred via the nonradiative co-operative processes {sup 4}I{sub 11/2{yields}} {sup 4}I{sub 15/2}, {sup 4}I{sub 11/2{yields}} {sup 4}F{sub 7/2}, {sup 4}I{sub 11/2{yields}} {sup 4}I{sub 15/2}, {sup 4}I{sub 13/2{yields}} {sup 4}F{sub 9/2}; and {sup 4}I{sub 13/2{yields}} {sup 4}I{sub 15/2}, {sup 4}I{sub 13/2{yields}} {sup 4}I{sub 9/2}, whose efficiency increases with increasing intensity of exciting radiation. It is shown that the cross-relaxation processes {sup 4}S{sub 3/2{yields}}{sup 4}I{sub 9/2}, {sup 4}I{sub 15/2{yields}}{sup 4}I{sub 13/2}, whose intensity depends on the concentration of Er{sup 3+} ions, are characteristic for Er:CNGG crystals with the Er atomic concentration above 1%. (active media)

  2. Nanosecond Pulsed Laser Processing of Ion Implanted Single Crystal Silicon Carbide Thin Layers

    NASA Astrophysics Data System (ADS)

    Özel, Tuğrul; Thepsonthi, Thanongsak; Amarasinghe, Voshadhi P.; Celler, George K.

    The attractiveness of single crystal SiC in a variety of high power, high voltage, and high temperature device applications such as electric vehicles and jet engines is counteracted by the very high cost of substrates. Precision cutting of multiple micrometre thick SiC layers and transferring them to lower cost substrates would drive the cost down and allow expanding the use of single crystal SiC. In this study, laser beam processing has been utilized to exfoliate thin layers from a surface of single crystal SiC that was prepared with hydrogen and boron ion implantation. The layer thickness of 1 μm has been achieved by ion implantation that formed voids and microcracks under the surface at a layer of 150 nm thick. High energy laser pulses provided the layer removal and its transfer to bonded Si substrate has been shown. Exfoliated surfaces and topography have been evaluated with Scanning Electron Microscopy. Furthermore, thermal modelling of pulse laser irradiation of implanted multi-layer SiC material has been conducted and temperature profiles are obtained at different peak pulse intensity settings to optimize exfoliation process parameters. It was found that laser exfoliation mechanism can be further improved by higher optical absorptance of defect rich layer obtained with boron ion implantation.

  3. Linear and nonlinear spectroscopy of tetravalent actinide ions in CeF{sub 4}

    SciTech Connect

    Liu, G.K.; Jursich, G.; Huang, J.; Beitz, J.V.; Williams, C.W.

    1993-10-01

    This paper reports laser spectroscopy studies on the tetravalent actinide ions Bk{sup 4+} and Cf{sup 4+} doped into CeF{sub 4}. Fluorescence line narrowing (FLN) and spectral hole burning (SHB) were applied to unravel the complex 5f-state spectra that arise from inhomogeneous line broadening and the presence of two intrinsic metal ion sites. When a persistent spectral hole was burned in an inhomogeneously broadened zero phonon line of 1 metal atom % Cf{sup 4+} in CeF{sub 4}, satellite spectral holes were also observed in other inhomogeneously broadened lines of Cf{sup 4+}. In the FLN spectra of 0.1 metal atom% Bk{sup 4+} in CeF{sub 4}, a linear relation was observed between excitation laser photon energy and energies of Bk{sup 4+} emission lines. This can be understood in terms of one limit of a general model of inhomogeneous broadening, namely the limit in which there is a one-to-one correspondence between optical transition energy and local structure in a disordered system.

  4. Energy loss of ions in a magnetized plasma: conformity between linear response and binary collision treatments.

    PubMed

    Nersisyan, H B; Zwicknagel, G; Toepffer, C

    2003-02-01

    The energy loss of a heavy ion moving in a magnetized electron plasma is considered within the linear response (LR) and binary collision (BC) treatments with the purpose to look for a connection between these two models. These two complementary approaches yield close results if no magnetic field is present, but there develop discrepancies with growing magnetic field at ion velocities that are lower than, or comparable with, the thermal velocity of the electrons. We show that this is a peculiarity of the Coulomb interaction which requires cutoff procedures to account for its singularity at the origin and its infinite range. The cutoff procedures in the LR and BC treatments are different as the order of integrations in velocity and in ordinary (Fourier) spaces is reversed in both treatments. While BC involves a velocity average of Coulomb logarithms, there appear in LR Coulomb logarithms of velocity averaged cutoffs. The discrepancies between LR and BC vanish, except for small contributions of collective modes, for smoothened potentials that require no cutoffs. This is shown explicitly with the help of an improved BC in which the velocity transfer is treated up to second order in the interaction in Fourier space.

  5. EPR study of Cu(2+) ion doped orotato(nicotinamid)cobalt(II) single crystal.

    PubMed

    Yıldırım, I; Karabulut, B; Büyükgüngör, O

    2016-01-05

    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.

  6. 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.

  7. 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.

  8. 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).

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

    SciTech Connect

    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

    2016-02-15

    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.

  10. 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.

  11. Crystallization kinetics and phase transformations in aluminum ion-implanted electrospun TiO2 nanofibers

    NASA Astrophysics Data System (ADS)

    Albetran, H.; Low, I. M.

    2016-12-01

    Electrospun TiO2 nanofibers were implanted with aluminum ions, and their crystallization kinetics, phase transformations, and activation energies were investigated from 25 to 900 °C by in situ high-temperature synchrotron radiation diffraction. The amorphous non-implanted and Al ion-implanted TiO2 nanofibers transformed to crystalline anatase at 600 °C and to rutile at 700 °C. The TiO2 phase transformation of the Al ion-implanted material was accelerated relative to non-implanted sample. Compared with non-implanted nanofibers, the Al-implanted materials yielded a decreased activation energies from 69(17) to 29(2) kJ/mol for amorphous-to-anatase transformation and from 112(15) to 129(5) kJ/mol for anatase-to-rutile transformation. A substitution of smaller Al ions for Ti in the TiO2 crystal structure results in accelerated titania phase transformation and a concomitant reduction in the activation energies.

  12. Crystal structures of Bacillus alkaline phytase in complex with divalent metal ions and inositol hexasulfate.

    PubMed

    Zeng, Yi-Fang; Ko, Tzu-Ping; Lai, Hui-Lin; Cheng, Ya-Shan; Wu, Tzu-Hui; Ma, Yanhe; Chen, Chun-Chi; Yang, Chii-Shen; Cheng, Kuo-Joan; Huang, Chun-Hsiang; Guo, Rey-Ting; Liu, Je-Ruei

    2011-06-03

    Alkaline phytases from Bacillus species, which hydrolyze phytate to less phosphorylated myo-inositols and inorganic phosphate, have great potential as additives to animal feed. The thermostability and neutral optimum pH of Bacillus phytase are attributed largely to the presence of calcium ions. Nonetheless, no report has demonstrated directly how the metal ions coordinate phytase and its substrate to facilitate the catalytic reaction. In this study, the interactions between a phytate analog (myo-inositol hexasulfate) and divalent metal ions in Bacillus subtilis phytase were revealed by the crystal structure at 1.25 Å resolution. We found all, except the first, sulfates on the substrate analog have direct or indirect interactions with amino acid residues in the enzyme active site. The structures also unraveled two active site-associated metal ions that were not explored in earlier studies. Significantly, one metal ion could be crucial to substrate binding. In addition, binding of the fourth sulfate of the substrate analog to the active site appears to be stronger than that of the others. These results indicate that alkaline phytase starts by cleaving the fourth phosphate, instead of the third or the sixth that were proposed earlier. Our high-resolution, structural representation of Bacillus phytase in complex with a substrate analog and divalent metal ions provides new insight into the catalytic mechanism of alkaline phytases in general.

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

    DOE PAGES

    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

  14. 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.

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

    PubMed

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

    2015-05-01

    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.

  16. Friction. Tuning friction atom-by-atom in an ion-crystal simulator.

    PubMed

    Bylinskii, Alexei; Gangloff, Dorian; Vuletić, Vladan

    2015-06-05

    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.

  17. 3D lattice distortions and defect structures in ion-implanted nano-crystals

    DOE PAGES

    Hofmann, Felix; Robinson, Ian K.; Tarleton, Edmund; ...

    2017-04-06

    The ability of Focused Ion Beam (FIB) techniques to cut solid matter at the nano-scale revolutionized the study of material structure across the life-, earth- and material sciences. But a detailed understanding of the damage caused by the ion beam and its effect on material properties remains elusive. We examine this damage in 3D using coherent X-ray diffraction to measure the full lattice strain tensor in FIB-milled gold nano-crystals. We also found that even very low ion doses, previously thought to be negligible, cause substantial lattice distortions. At higher doses, extended self-organized defect structures appear. Combined with detailed numerical calculations,more » these observations allow fundamental insight into the nature of the damage created and the structural instabilities that lead to a surprisingly inhomogeneous morphology.« less

  18. 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.

  19. Mechanical, thermal, linear and nonlinear optical properties of barium L-tartrate single crystal

    NASA Astrophysics Data System (ADS)

    Rajesh, K.; Praveen Kumar, P.

    2017-01-01

    A potential semiorganic nonlinear optical (NLO) single crystal of barium L-tartrate (BaTr) was grown by slow evaporation technique. Single and powder x-ray diffraction study was carried out for the grown crystal. The hardness of the material was carried out by a Vickers micro hardness tester. Thermal behavior of the crystal was studied by TG-DTA thermal analyzer. Optical and electrical conductivity of the crystal was measured by photo conductivity and dielectric studies. NLO property of the crystal is confirmed by Kurt–Perry powder technique. Laser damage threshold (LDT) value of the grown crystal has been carried out using a Q-switched Nd:YAG laser beam.

  20. Linear and nonlinear obliquely propagating ion-acoustic waves in magnetized negative ion plasma with non-thermal electrons

    NASA Astrophysics Data System (ADS)

    Mishra, M. K.; Jain, S. K.; Jain

    2013-10-01

    Ion-acoustic solitons in magnetized low-β plasma consisting of warm adiabatic positive and negative ions and non-thermal electrons have been studied. The reductive perturbation method is used to derive the Korteweg-de Vries (KdV) equation for the system, which admits an obliquely propagating soliton solution. It is found that due to the presence of finite ion temperature there exist two modes of propagation, namely fast and slow ion-acoustic modes. In the case of slow-mode if the ratio of temperature to mass of positive ion species is lower (higher) than the negative ion species, then there exist compressive (rarefactive) ion-acoustic solitons. It is also found that in the case of slow mode, on increasing the non-thermal parameter (γ) the amplitude of the compressive (rarefactive) soliton decreases (increases). In fast ion-acoustic mode the nature and characteristics of solitons depend on negative ion concentration. Numerical investigation in case of fast mode reveals that on increasing γ, the amplitude of compressive (rarefactive) soliton increases (decreases). The width of solitons increases with an increase in non-thermal parameters in both the modes for compressive as well as rarefactive solitons. There exists a value of critical negative ion concentration (α c ), at which both compressive and rarefactive ion-acoustic solitons appear as described by modified KdV soliton. The value of α c decreases with increase in γ.

  1. Calcium carbonate crystallization in the presence of modified polysaccharides and linear polymeric additives

    NASA Astrophysics Data System (ADS)

    Matahwa, H.; Ramiah, V.; Sanderson, R. D.

    2008-10-01

    Crystallization of calcium carbonate was performed in the presence of grafted polysaccharides, polyacrylamide (PAM) and polyacrylic acid (PAA). The grafted polysaccharides gave crystal morphologies that were different from the unmodified polysaccharides but similar to the ones given by homopolymers of the grafted chains. PAM-grafted α-cellulose gave rectangular platelets that aggregated to form 'spherical' crystals on the surface of the fiber, whereas PAA grafted α-cellulose gave spherical crystals on the surface of the fiber. X-ray diffraction (XRD) spectroscopy showed that PAM-grafted α-cellulose, PAM as well as the control (no polymeric additive) gave calcite crystals at both 25 and 80 °C. However, the PAA-grafted α-cellulose and PAA homopolymer gave calcite and vaterite crystals at 25 °C with calcite and aragonite crystals along with traces of vaterite being formed at 80 °C. The fiber surface coverage by these crystals was more on the acrylic- and acrylamide-grafted cellulose than on the ungrafted α-cellulose. The evolution of CaCO 3 polymorphs as well as crystal morphology in PAA-grafted starch was similar to that of PAA-grafted α-cellulose at the two temperatures employed.

  2. CID of singly charged antioxidants applied in lubricants by means of a 3D ion trap and a linear ion trap-Orbitrap mass spectrometer.

    PubMed

    Kassler, Alexander; Pittenauer, Ernst; Doerr, Nicole; Allmaier, Guenter

    2011-06-01

    The aim of this study was to investigate the fragmentation behavior induced by low-energy collision-induced dissociation (LE-CID) of four selected antioxidants applied in lubricants, by two different types of ion trap mass spectrometers: a three-dimensional ion trap (3D-IT) and a linear IT (LIT) Orbitrap MS. Two sterically hindered phenols and two aromatic amines were selected as model compounds representing different antioxidant classes and were characterized by positive-ion electrospray ionization (ESI) and LE-CID. Various types of molecular ions (e.g. [M](+•) , [M + H](+) , [M + NH(4) ](+) or [M + Na](+) ) were used as precursor ions generating a significant number of structurally relevant product ions. Furthermore, the phenolic compounds were analyzed by negative-ion ESI. For both IT types applied for fragmentation, the antioxidants exhibited the same unusual LE-CID behavior: (1) they formed stable radical product ions and (2) CC bond cleavages of aliphatic substituents were observed and their respective cleavage sites depended on the precursor ion selected. This fragmentation provided information on the type of structural isomer usually not obtainable for branched aliphatic substituents utilizing LE-CID. Comparing the two instruments, the main benefit of applying the LIT-Orbitrap was direct access to elemental composition of product ions enabling unambiguous interpretation of fragmentation trees not obtainable by the 3D-IT device (e.g. loss of isobaric neutrals). It should be emphasized that the types of product ions formed do not depend on the type of IT analyzer applied. For characterizing degradation products of antioxidants, the LIT-Orbitrap hybrid system, allowing the determination of accurate m/z values for product ions, is the method of choice.

  3. 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.

  4. Quantum-mechanical description of ions in crystals: Electronic structure of magnesium oxide

    NASA Astrophysics Data System (ADS)

    Luaña, Víctor; Recio, J. M.; Pueyo, L.

    1990-07-01

    The electronic structure of the MgO crystal has been calculated with the recently reported ab initio perturbed-ion (PI) method, a scheme derived from the theory of electronic separability of multielectron systems and the ab initio model-potential approach of Huzinaga. The PI atomiclike orbitals are eigenfunctions of Fock operators that contain nuclear, Coulombic, and exchange lattice potentials plus lattice projection operators enforcing the ion-lattice orthogonality. These lattice-consistent ionic orbitals form a crystalline basis set that may be useful in a variety of applications. The PI bonding picture of MgO consists of lattice-stabilized Mg2+ and O2- ions described with well-separated wave functions. The PI electron density of Mg2+ is very close to the free-ion function, but that of the oxide is more contracted than the density of O2- in vacuo. The PI densities are tested and compared with others by computing diamagnetic susceptibilities, form factors, and the change of electronic kinetic energy upon crystal formation. The PI method also gives the bulk properties of the crystal. The predicted equilibrium geometry is 0.11 Å larger than the observed value, and the lattice binding energy is 100 kcal mol-1 shorter. These results improve when the correlation energy is computed from the PI wave functions with the Coulomb-hole treatment of Clementi. The PI calculation including electron correlation reproduces the experimental equilibrium geometry within 0.001 Å, the bulk modulus within 1 GPa, and the binding energy within 25 kcal mol-1. Furthermore, the computed pressure effects on the cell volume and bulk modulus of the rocksalt phase match the available experimental data up to at least 30 GPa.

  5. 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.

  6. Linear Chains of Magnetic Ions Stacked with Variable Distance: Ferromagnetic Ordering with a Curie Temperature above 20 K.

    PubMed

    Friedländer, Stefan; Liu, Jinxuan; Addicoat, Matt; Petkov, Petko; Vankova, Nina; Rüger, Robert; Kuc, Agnieszka; Guo, Wei; Zhou, Wencai; Lukose, Binit; Wang, Zhengbang; Weidler, Peter G; Pöppl, Andreas; Ziese, Michael; Heine, Thomas; Wöll, Christof

    2016-10-04

    We have studied the magnetic properties of the SURMOF-2 series of metal-organic frameworks (MOFs). Contrary to bulk MOF-2 crystals, where Cu(2+) ions form paddlewheels and are antiferromagnetically coupled, in this case the Cu(2+) ions are connected via carboxylate groups in a zipper-like fashion. This unusual coupling of the spin 1/2 ions within the resulting one-dimensional chains is found to stabilize a low-temperature, ferromagnetic (FM) phase. In contrast to other ordered 1D systems, no strong magnetic fields are needed to induce the ferromagnetism. The magnetic coupling constants describing the interaction between the individual metal ions have been determined in SQUID experiments. They are fully consistent with the results of ab initio DFT electronic structure calculations. The theoretical results allow the unusual magnetic behavior of this exotic, yet easy-to-fabricate, material to be described in a detailed fashion.

  7. 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

  8. Crystal field and magnetism of Pr3+ and Nd3+ ions in orthorhombic perovskites

    NASA Astrophysics Data System (ADS)

    Novák, P.; Knížek, K.; Maryško, M.; Jirák, Z.; Kuneš, J.

    2013-11-01

    Fifteen parameters characterizing the crystal field of rare-earth ions in the RMO3 perovskites (R=Pr, Nd, M=Ga, Co) are calculated using a first-principles electronic structure and the Wannier projection. The method contains a single adjustable parameter that characterizes the hybridization of R(4f) states with the states of oxygen ligands. Subsequently the energy levels and magnetic moments of the trivalent R ion are determined by diagonalization of an effective Hamiltonian which, besides the crystal field, contains the 4f electron-electron repulsion, spin-orbit coupling and interaction with magnetic field. In the Ga compounds the energy levels of the ground multiplet agree within a few meV with those determined experimentally by other authors. For all four compounds in question the temperature dependence of magnetic susceptibility is measured on polycrystalline samples and compared with the results of calculation. For NdGaO3 the theory is also compared with the magnetic measurements on a single crystal presented by Luis et al (1998 Phys. Rev. B 58 798). Good agreement between the experiment and theory is found.

  9. Applications of metal ions and liquid crystals for multiplex detection of DNA.

    PubMed

    Liu, Yanyang; Yang, Kun-Lin

    2015-02-01

    Many cations such as sodium ions have strong influence on anchoring behaviors of liquid crystals (LC). Since DNA is negatively charged and forms complex with metal ions, it is possible to form DNA/metal ions complex on surfaces to disrupt orientations of LC. This phenomenon is used to establish a principle for detecting surface immobilized DNA by using LC. In contrast, peptide nucleic acid (PNA) is electroneutral. It does not complex with metal ions or affect the orientations of LC. Therefore, PNA can be used as a probe to hybridize with specific DNA with a unique sequence, and the principle mentioned above can be used to detect the DNA target by using metal ions and LC. Based on this method, a 600bp DNA target in buffer can be detected with a limit of detection at 10fM. Unlike other fluorescence-based DNA assays, this LC-based detection method does not require labeling of DNA, and the test result can be viewed with the naked eye under a polarized microscope.

  10. Investigation on the influence of foreign metal ions in crystal growth and characterization of L-Alaninium Maleate (LAM) single crystals.

    PubMed

    Ruby Nirmala, L; Thomas Joseph Prakash, J

    2013-11-01

    A Nonlinear Optical, good quality, single crystals of doped and undoped l-Alaninium Maleate (LAM) were grown by slow evaporation solution growth technique at room temperature. The lattice parameters were analyzed by single crystal X-ray diffraction technique. The identification of Cadmium ion in the doped crystals was done using the EDAX spectrum. The presence of functional group of the dopant with LAM molecule was studied using FTIR spectra. The results of UV-Vis study is used to compare the transparencies of the doped and undoped LAM crystals. The optical band gap energy of the grown crystal was also calculated. The relative second harmonic generation (SHG) efficiency measurement with KDP reference is used to find the incorporation of metal to l-Alaninium Maleate crystals and the parent material. Also the thermal stability of the grown crystals was studied by TGA/DTA spectrum. The mechanical stability of the grown crystals was confirmed through Vickers micro hardness study. By parallel plate capacitor technique, the dielectric response was studied over a wide range of frequencies at different temperatures. The various studies showed the incorporation of the impurity Cd(2+) into LAM crystals and the investigations indicated that the impurity played an important role in the changes of the spectral and structural properties of LAM crystals.

  11. Plasticized poly(vinyl chloride)-based photonic crystal for ion sensing.

    PubMed

    Aki, Shoma; Endo, Tatsuro; Sueyoshi, Kenji; Hisamoto, Hideaki

    2014-12-16

    In this study, we, for the first time, developed a plasticized poly(vinyl chloride) (PVC)-based two-dimensional photonic crystal (2D-PhC) optical sensor using nanoimprint lithography (NIL), which can perform highly sensitive, fast, and selective ion sensing based on ion extraction. Concerning the principle of response, present plasticized PVC-based PhC works as a waveguide and a grating. Incident light was guided in the bulk of plasticized PVC and, then, guided light of a specific wavelength was diffracted by a periodic nanostructure. The guided and diffracted light intensity changes of PVC-based PhCs possessing various thicknesses were monitored at 580 nm; then, we found that the 0.35 μm-thick PhC film exhibited the highest diffraction intensity. For the ion-sensing application, potassium-selective sensing elements involving potassium ionophore and lipophilic dye were dissolved in a plasticized PVC-based PhC, and the K(+)-selective response was successfully observed by monitoring the diffracted peak intensity change. The present 2D-PhC optical sensor exhibited a fast response within 5 s (95% response time) due to the use of thin film, and sensitivity was 20 times higher than that of a PVC plane-film optical sensor, due to efficient collection of diffracted light by employing a periodic nanostructure of the photonic crystal.

  12. Establishing consistent van der Waals volumes of polyatomic ions from crystal structures.

    PubMed

    Beichel, Witali; Eiden, Philipp; Krossing, Ingo

    2013-10-07

    Based on temperature (T) dependent crystal structure data of seven organic salts, a radii-based scheme for the calculation of the van der Waals volume (V(vdw)) is analyzed. The obtained volumes (V(vdw,r), r=radius-based) are nearly T independent. An ion volume partitioning scheme is proposed by fixing the anion volumes of [Cl](-), [Br](-), [I](-), [BF(4)](-), [PF(6)](-), [OTf](-) and [NTf(2)](-). The van der Waals volumes (V(vdw,r) (+/-)) of 48 ions are established, with low standard deviations (0.2-3.6 Å(3), 0.1-4.5 % of V(vdw,r) (+/-)). The ion volumes are independent of the counterion and one crystal structure already suffices for their derivation. Correlations of the viscosity with V(vdw,r) via a Litovitz ansatz and our recently derived Arrhenius-type approach prove that these volumes are suitable for the volume-based description and prediction of IL properties. The corresponding correlation coefficient for the latter is R(2)=0.86 for 40 ILs (354 data points) in the T range of 253-373 K.

  13. Selective laser spectroscopy of SrF2 crystal doped with Pr3+ ions

    NASA Astrophysics Data System (ADS)

    Alimov, O. K.; Doroshenko, M. E.; Konyushkin, V. A.; Papashvili, A. G.; Osiko, V. V.

    2016-01-01

    SrF2 crystals doped with Pr3+ ions with concentrations corresponding to 0.5, 1.0 and 2.0 wt % of PrF3 are studied by selective laser excitation. The absorption and luminescence spectra of Pr3 ions are measured at a temperature of 77 K. Three types of tetragonal centres (C, E, S) with the point symmetry group C4v and three types of cluster centres (K1, K2, K3) are found. Energy level diagrams of the 3H4, 3P1 and 3P2 terms of Pr3+ ions in SrF2 crystals are plotted for the tetragonal (C) and cluster optical centres. The lifetimes of the tetragonal C centre [τ(300 K) ~ 112 μs, τ(77 K) ~108 μs] and cluster centres K1 (~43 μs), K2 (~7 μs) and K3 (~48 μs) are measured at 77 K for the first time.

  14. 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.

  15. 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.

  16. 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.

  17. 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

    2016-08-16

    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.

  18. Visible to near-infrared supercontinuum generation in yttrium orthosilicate bulk crystal and ion implanted planar waveguide

    NASA Astrophysics Data System (ADS)

    Xiang, Bingxi; Ren, Xikui; Ruan, Shuangchen; Wang, Lei; Yan, Peiguang; Han, Huangpu; Wang, Meng; Yin, Jinde

    2016-08-01

    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.

  19. 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

  20. Breakthrough performance of linear-DNA on ion-exchange membrane columns.

    PubMed

    Ma Montesinos-Cisneros, Rosa; Ortega, Jaime; Guzmán, Roberto; Tejeda-Mansir, Armando

    2006-07-01

    Breakthrough performance of linear-DNA adsorption on ion-exchange membrane columns was theoretically and experimentally investigated using batch and fixed-bed systems. System dispersion curves showed the absence of flow non-idealities in the experimental arrangement. Breakthrough curves were not significantly affected by flow-rate or inlet solution concentration. In the theoretical analysis a model was integrated by the serial coupling of the membrane transport model and the system dispersion model. A transport model that considers finite kinetic rate and column dispersed flow was used in the study. A simplex optimization routine coupled to the solution of the partial differential model equations was employed to estimate the maximum adsorption capacity constant, the equilibrium desorption constant and the forward interaction rate-constant, which are the parameters of the membrane transport model. Through this approach a good prediction of the adsorption phenomena is obtained for inlet concentrations and flow rates greater than 0.2 mg/ml and 0.16 ml/min.

  1. MSM, an Efficient Workflow for Metabolite Identification Using Hybrid Linear Ion Trap Orbitrap Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Cho, Robert; Huang, Yingying; Schwartz, Jae C.; Chen, Yan; Carlson, Timothy J.; Ma, Ji

    2012-05-01

    Identification of drug metabolites can often yield important information regarding clearance mechanism, pharmacologic activity, or toxicity for drug candidate molecules. Additionally, the identification of metabolites can provide beneficial structure-activity insight to help guide lead optimization efforts towards molecules with optimal metabolic profiles. There are challenges associated with detecting and identifying metabolites in the presence of complex biological matrices, and new LC-MS technologies have been developed to meet these challenges. In this report, we describe the development of an experimental approach that applies unique features of the hybrid linear ion trap Orbitrap mass spectrometer to streamline in vitro and in vivo metabolite identification experiments. The approach, referred to as MSM, utilizes multiple collision cells, dissociation methods, mass analyzers, and detectors. With multiple scan types and different dissociation modes built into one experimental method, along with flexible post-acquisition analysis options, the MSM workflow offers an attractive option to fast and reliable identification of metabolites in different kinds of in vitro and in vivo samples. The MSM workflow was successfully applied to metabolite identification analysis of verapamil in both in vitro rat hepatocyte incubations and in vivo rat bile samples.

  2. 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.

  3. A thermodynamic and crystal structure study of thermally aged lithium ion cells

    NASA Astrophysics Data System (ADS)

    Maher, Kenza; Yazami, Rachid

    2014-09-01

    Lithium ion batteries in the coin-cell form factor (2032) initially charged to 4.2 V at ambient temperature are stored at 60 °C and 70 °C for up to 8 weeks. The cells discharge capacity (Qd) and thermodynamic properties, including open-circuit potential (OCP), entropy (ΔS) and enthalpy (ΔH) are measured after each completed ageing week. Post-mortem analysis of aged anodes and cathodes is investigated by X-ray diffractometry (XRD) and Raman Scattering spectrometry (RS) in an attempt to correlate thermodynamic data to changes in the crystal structure characteristics. It is found that degradation of the electrode materials' crystal structure accounts for most of the observed changes in the cells' thermodynamics with well quantified and distinct contributions from anode and cathode.

  4. 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).

  5. Investigations on the vibrational modes and non-linear optical properties of 4-Fluoro Chalcone crystal.

    PubMed

    Prabu, S; Nagalakshmi, R; Balaji, J; Srinivasan, P

    2014-08-14

    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.

  6. 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.

  7. Crystal orientation dependence of ion-irradiation hardening in pure tungsten

    NASA Astrophysics Data System (ADS)

    Hasenhuetl, Eva; Zhang, Zhexian; Yabuuchi, Kiyohiro; Song, Peng; Kimura, Akihiko

    2017-04-01

    Pure tungsten (W) single crystals of {0 0 1} and {0 1 1} surface orientations were irradiated with 6.4 MeV Fe3+ ions up to 1 dpa at 573 K. The TEM examination revealed that there was a very small orientation dependence in the radiation damaged microstructure, showing that both W{0 0 1} and W{0 1 1} exhibited a double black band structure with high number density of dislocation loop rafts in the black bands. However, the depth profile of ion-irradiation hardening evaluated by nanoindentation (NI) technique turned out to show a clear orientation dependence, namely, W{0 0 1} showed a deeper NI hardness profile than W{0 1 1}.

  8. 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.

  9. Ion beam mixing effects in Ag precipitates embedded in MgO crystals

    NASA Astrophysics Data System (ADS)

    Fuchs, G.; Abouchacra, G.; Treilleux, M.; Thevenard, P.; Serughetti, J.

    1988-05-01

    MgO single crystals have been implanted at room temperature with 8 × 10 16 Ag cm -2 of 180 keV energy. After 973 K thermal annealing, Ag atoms precipitate in the MgO matrix. The MgOAg samples were then irradiated at 77 K with 800 keV xenon up to 1.7 × 10 16 ions cm -2. The modification of the metallic precipitated phase induced by such ionic bombardment, has been characterized by optical absorption spectroscopy (OAS) and transmission electron microscopy (TEM). The evolution of the optical spectra with xenon bombardment has been interpreted in terms of silver precipitate dispersion induced by ion beam mixing effects. The inhibition of atomic diffusion or radiation induced diffusion, due the low sample temperature during irradiation, increases the efficiency of atomic mixing effects. TEM observations confirm this assumption.

  10. Sensitization of neodymium ion luminescence by chromium ions in a Gd/sub 3/Ga/sub 5/O/sub 12/ crystal

    SciTech Connect

    Zharikov, E.V.; Il'ichev, N.N.; Laptev, V.V.; Malyutin, A.A.; Ostroumov, V.G.; Pashinin, P.P.; Shcherbakov, I.A.

    1982-03-01

    An investigation is reported of the spectral, luminescence, and lasing properties of a Gd/sub 3/Ga/sub 5/O/sub 12/ crystal activated with chromium and neodymium ions. The high efficiency of the energy transfer process from chromium to neodymium ions is demonstrated. For example, the probability of an elementary Cr/sup 3 +/--Nd/sup 3 +/ interaction event in a Gd/sub 3/Ga/sub 5/O/sub 12/ crystal was 12 times higher than that in a Y/sub 3/Al/sub 5/O/sub 12/ crystal. It was found that sensitization of neodymium ion luminescence by chromium ions can increase severalfold the energy characteristics of cw and pulsed neodymium lasers. An investigation of the free-lasing parameters shows that the ultimate differential lasing efficiency of neodymium in a Gd/sub 3/Ga/sub 5/O/sub 12/:Cr:Nd crystal is 3.6 times higher than that for a YAG:Nd crystal under comparable conditions.

  11. Very low loss reactively ion etched Tellurium Dioxide planar rib waveguides for linear and non-linear optics.

    PubMed

    Madden, S J; Vu, K T

    2009-09-28

    We report on the fabrication and optical properties of the first very low loss nonlinear Tellurite planar rib waveguides ever demonstrated. A new reactive ion etch process based on Hydrogen as the active species was developed to accomplish the low propagation losses. Optical losses below approximately 0.05 dB/cm in most of the NIR spectrum and approximately 0.10 dB/cm at 1550 nm have been achieved - the lowest ever reported by more than an order of magnitude and clearly suitable for planar integrated devices. We demonstrate strong spectral broadening of 0.6 ps pulses in waveguides fabricated from pure TeO(2), in good agreement with simulations.

  12. Integrated RF photonic devices based on crystal ion sliced lithium niobate

    NASA Astrophysics Data System (ADS)

    Stenger, Vincent; Toney, James; Pollick, Andrea; Busch, James; Scholl, Jon; Pontius, Peter; Sriram, Sri

    2013-03-01

    This paper reports on the development of thin film lithium niobate (TFLN™) electro-optic devices at SRICO. TFLN™ is formed on various substrates using a layer transfer process called crystal ion slicing. In the ion slicing process, light ions such as helium and hydrogen are implanted at a depth in a bulk seed wafer as determined by the implant energy. After wafer bonding to a suitable handle substrate, the implanted seed wafer is separated (sliced) at the implant depth using a wet etching or thermal splitting step. After annealing and polishing of the slice surface, the transferred film is bulk quality, retaining all the favorable properties of the bulk seed crystal. Ion slicing technology opens up a vast design space to produce lithium niobate electro-optic devices that were not possible using bulk substrates or physically deposited films. For broadband electro-optic modulation, TFLN™ is formed on RF friendly substrates to achieve impedance matched operation at up to 100 GHz or more. For narrowband RF filtering functions, a quasi-phase matched modulator is presented that incorporates domain engineering to implement periodic inversion of electro-optic phase. The thinness of the ferroelectric films makes it possible to in situ program the domains, and thus the filter response, using only few tens of applied volts. A planar poled prism optical beam steering device is also presented that is suitable for optically switched true time delay architectures. Commercial applications of the TFLN™ device technologies include high bandwidth fiber optic links, cellular antenna remoting, photonic microwave signal processing, optical switching and phased arrayed radar.

  13. Crystal lattice properties fully determine short-range interaction parameters for alkali and halide ions

    NASA Astrophysics Data System (ADS)

    Mao, Albert H.; Pappu, Rohit V.

    2012-08-01

    Accurate models of alkali and halide ions in aqueous solution are necessary for computer simulations of a broad variety of systems. Previous efforts to develop ion force fields have generally focused on reproducing experimental measurements of aqueous solution properties such as hydration free energies and ion-water distribution functions. This dependency limits transferability of the resulting parameters because of the variety and known limitations of water models. We present a solvent-independent approach to calibrating ion parameters based exclusively on crystal lattice properties. Our procedure relies on minimization of lattice sums to calculate lattice energies and interionic distances instead of equilibrium ensemble simulations of dense fluids. The gain in computational efficiency enables simultaneous optimization of all parameters for Li+, Na+, K+, Rb+, Cs+, F-, Cl-, Br-, and I- subject to constraints that enforce consistency with periodic table trends. We demonstrate the method by presenting lattice-derived parameters for the primitive model and the Lennard-Jones model with Lorentz-Berthelot mixing rules. The resulting parameters successfully reproduce the lattice properties used to derive them and are free from the influence of any water model. To assess the transferability of the Lennard-Jones parameters to aqueous systems, we used them to estimate hydration free energies and found that the results were in quantitative agreement with experimentally measured values. These lattice-derived parameters are applicable in simulations where coupling of ion parameters to a particular solvent model is undesirable. The simplicity and low computational demands of the calibration procedure make it suitable for parametrization of crystallizable ions in a variety of force fields.

  14. 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.

  15. Linear dispersion relation of beta-induced Alfvén eigenmodes in presence of anisotropic energetic ions

    SciTech Connect

    Ma, Ruirui; Chavdarovski, Ilija; Ye, Gaoxiang; Wang, Xin

    2014-06-15

    Using the theoretical framework of the generalized fishbone-like dispersion relation, the linear properties of beta-induced Alfvén eigenmodes (BAEs) and energetic particle continuum modes (EPMs) excited by anisotropic slowing-down energetic ions are investigated analytically and numerically. The resonant contribution of energetic ions to the potential energy perturbation as well as fluid-like term describing the background plasma and adiabatic contribution of energetic ions are derived. For high-mode numbers, numerical results show smooth transition between the EP continuous spectrum and BAEs in the gap. EPMs and/or BAEs are destabilized by energetic ions, with real frequencies and growth rates strongly dependent on the energetic particle density and resonant frequency.

  16. Linear dispersion relation of beta-induced Alfvén eigenmodes in presence of anisotropic energetic ions

    NASA Astrophysics Data System (ADS)

    Ma, Ruirui; Chavdarovski, Ilija; Ye, Gaoxiang; Wang, Xin

    2014-06-01

    Using the theoretical framework of the generalized fishbone-like dispersion relation, the linear properties of beta-induced Alfvén eigenmodes (BAEs) and energetic particle continuum modes (EPMs) excited by anisotropic slowing-down energetic ions are investigated analytically and numerically. The resonant contribution of energetic ions to the potential energy perturbation as well as fluid-like term describing the background plasma and adiabatic contribution of energetic ions are derived. For high-mode numbers, numerical results show smooth transition between the EP continuous spectrum and BAEs in the gap. EPMs and/or BAEs are destabilized by energetic ions, with real frequencies and growth rates strongly dependent on the energetic particle density and resonant frequency.

  17. 3D lattice distortions and defect structures in ion-implanted nano-crystals

    PubMed Central

    Hofmann, Felix; Tarleton, Edmund; Harder, Ross J.; Phillips, Nicholas W.; Ma, Pui-Wai; Clark, Jesse N.; Robinson, Ian K.; Abbey, Brian; Liu, Wenjun; Beck, Christian E.

    2017-01-01

    Focussed Ion Beam (FIB) milling is a mainstay of nano-scale machining. By manipulating a tightly focussed beam of energetic ions, often gallium (Ga+), FIB can sculpt nanostructures via localised sputtering. This ability to cut solid matter on the nano-scale revolutionised sample preparation across the life, earth and materials sciences. Despite its widespread usage, detailed understanding of the FIB-induced structural damage, intrinsic to the technique, remains elusive. Here we examine the defects caused by FIB in initially pristine objects. Using Bragg Coherent X-ray Diffraction Imaging (BCDI), we are able to spatially-resolve the full lattice strain tensor in FIB-milled gold nano-crystals. We find that every use of FIB causes large lattice distortions. Even very low ion doses, typical of FIB imaging and previously thought negligible, have a dramatic effect. Our results are consistent with a damage microstructure dominated by vacancies, highlighting the importance of free-surfaces in determining which defects are retained. At larger ion fluences, used during FIB-milling, we observe an extended dislocation network that causes stresses far beyond the bulk tensile strength of gold. These observations provide new fundamental insight into the nature of the damage created and the defects that lead to a surprisingly inhomogeneous morphology. PMID:28383028

  18. Progress toward a practical laser driven ion source using variable thickness liquid crystal targets

    NASA Astrophysics Data System (ADS)

    Poole, Patrick; Cochran, Ginevra; Zeil, Karl; Metzkes, Josephine; Obst, Lieselotte; Kluge, Thomas; Schlenvoigt, Hans-Peter; Prencipe, Irene; Cowan, Tom; Schramm, Uli; Schumacher, Douglass

    2016-10-01

    Ion acceleration from ultra-intense laser interaction has been long investigated in pursuit of requisite energies and spectral distributions for applications like proton cancer therapy. However, the details of ion acceleration mechanisms and their laser intensity scaling are not fully understood, especially the complete role of pulse contrast and target thickness. Additionally, target delivery and alignment at appropriate rates for study and subsequent treatment pose significant challenges. We present results from a campaign on the Draco laser using liquid crystal targets that have on-demand, in-situ thickness tunability over more than three orders of magnitude, enabling rapid data collection due to <1 minute, automatically aligned target formation. Diagnostics include spectral and spatial measurement of ions, electrons, and reflected and transmitted light, all with thickness, laser focus, and pulse contrast variations. In particular we discuss optimal thickness vs. contrast and details of ultra-thin target normal ion acceleration, along with supporting particle-in-cell studies. This work was supported by the DARPA PULSE program through AMRDEC, by the NNSA (DE-NA0001976), by EC Horizon 2020 LASERLAB-EUROPE/LEPP (654148), and by the German Federal Ministry of Education and Research (BMBF, 03Z1O511).

  19. Persistent photoconductivity in oxygen-ion implanted KNbO3 bulk single crystal

    NASA Astrophysics Data System (ADS)

    Tsuruoka, R.; Shinkawa, A.; Nishimura, T.; Tanuma, C.; Kuriyama, K.; Kushida, K.

    2016-12-01

    Persistent Photoconductivity (PPC) in oxygen-ion implanted KNbO3 ([001] oriented bulk single crystals; perovskite structure; ferroelectric with a band gap of 3.16 eV) is studied in air at room temperature to prevent the degradation of its crystallinity caused by the phase transition. The residual hydrogens in un-implanted samples are estimated to be 5×1014 cm-2 from elastic recoil detection analysis (ERDA). A multiple-energy implantation of oxygen ions into KNbO3 is performed using energies of 200, 400, and 600 keV (each ion fluence:1.0×1014 cm-2). The sheet resistance varies from >108 Ω/□ for an un-implanted sample to 1.9×107 Ω/□ for as-implanted one, suggesting the formation of donors due to hydrogen interstitials and oxygen vacancies introduced by the ion implantation. The PPC is clearly observed with ultraviolet and blue LEDs illumination rather than green, red, and infrared, suggesting the release of electrons from the metastable conductive state below the conduction band relating to the charge states of the oxygen vacancy.

  20. Ion Bernstein instability dependence on the proton-to-electron mass ratio: Linear dispersion theory

    NASA Astrophysics Data System (ADS)

    Min, Kyungguk; Liu, Kaijun

    2016-07-01

    Fast magnetosonic waves, which have as their source ion Bernstein instabilities driven by tenuous ring-like proton velocity distributions, are frequently observed in the inner magnetosphere. One major difficulty in the simulation of these waves is that they are excited in a wide frequency range with discrete harmonic nature and require time-consuming computations. To overcome this difficulty, recent simulation studies assumed a reduced proton-to-electron mass ratio, mp/me, and a reduced light-to-Alfvén speed ratio, c/vA, to reduce the number of unstable modes and, therefore, computational costs. Although these studies argued that the physics of wave-particle interactions would essentially remain the same, detailed investigation of the effect of this reduced system on the excited waves has not been done. In this study, we investigate how the complex frequency, ω = ωr+iγ, of the ion Bernstein modes varies with mp/me for a sufficiently large c/vA (such that ωpe2/Ωe2≡(me/mp)(c/vA)2≫1) using linear dispersion theory assuming two different types of energetic proton velocity distributions, namely, ring and shell. The results show that low- and high-frequency harmonic modes respond differently to the change of mp/me. For the low harmonic modes (i.e., ωr˜Ωp), both ωr/Ωp and γ/Ωp are roughly independent of mp/me, where Ωp is the proton cyclotron frequency. For the high harmonic modes (i.e., Ωp≪ωr≲ωlh, where ωlh is the lower hybrid frequency), γ/ωlh (at fixed ωr/ωlh) stays independent of mp/me when the parallel wave number, k∥, is sufficiently large and becomes inversely proportional to (mp/me)1/4 when k∥ goes to zero. On the other hand, the frequency range of the unstable modes normalized to ωlh remains independent of mp/me, regardless of k∥.

  1. Microstructural, mechanical and optical properties research of a carbon ion-irradiated Y2SiO5 crystal

    DOE PAGES

    Song, Hong-Lian; Yu, Xiao-Fei; Huang, Qing; ...

    2017-01-28

    Ion irradiation has been a popular method to modify properties of different kinds of materials. Ion-irradiated crystals have been studied for years, but the effects on microstructure and optical properties during irradiation process are still controversial. In this study, we used 6 MeV C ions with a fluence of 1 × 1015 ion/cm2 irradiated Y2SiO5 (YSO) crystal at room temperature, and discussed the influence of C ion irradiation on the microstructure, mechanical and optical properties of YSO crystal by Rutherford backscattering/channeling analyzes (RBS/C), X-ray diffraction patterns (XRD), Raman, nano-indentation test, transmission and absorption spectroscopy, the prism coupling and the end-facetmore » coupling experiments. We also used the secondary ion mass spectrometry (SIMS) to analyze the elements distribution along sputtering depth. Finally, 6 MeV C ions with a fluence of 1 × 1015 ion/cm2 irradiated caused the deformation of YSO structure and also influenced the spectral properties and lattice vibrations.« less

  2. Diffusion of water and sodium counter-ions in nanopores of a β-lactoglobulin crystal: a molecular dynamics study.

    PubMed

    Malek, Kourosh; Odijk, Theo; Coppens, Marc-Olivier

    2005-07-01

    The dynamics of water and sodium counter-ions (Na(+)) in a C222(1) orthorhombic β-lactoglobulin crystal is investigated by means of 5 ns molecular dynamics simulations. The effect of the fluctuation of the protein atoms on the motion of water and sodium ions is studied by comparing simulations in a rigid and in a flexible lattice. The electrostatic interactions of sodium ions with the positively charged LYS residues inside the crystal channels significantly influence the ionic motion. According to our results, water molecules close to the protein surface undergo an anomalous diffusive motion. On the other hand, the motion of water molecules further away from the protein surface is normal diffusive. Protein fluctuations affect the diffusion constant of water, which increases from 0.646 ± 0.108 to 0.887 ± 0.41 nm(2) ns(-1), when protein fluctuations are taken into account. The pore size (0.63-1.05 nm) and the water diffusivities are in good agreement with previous experimental results. The dynamics of sodium ions is disordered. LYS residues inside the pore are the main obstacles to the motion of sodium ions. However, the simulation time is still too short for providing a precise description of anomalous diffusion of sodium ions. The results are not only of interest for studying ion and water transport through biological nanopores, but may also elucidate water-protein and ion-protein interactions in protein crystals.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Measurement of the electron and ion temperatures by the x-ray imaging crystal spectrometer on joint Texas experimental tokamak.

    PubMed

    Yan, W; Chen, Z Y; Jin, W; Lee, S G; Shi, Y J; Huang, D W; Tong, R H; Wang, S Y; Wei, Y N; Ma, T K; Zhuang, G

    2016-11-01

    An x-ray imaging crystal spectrometer has been developed on joint Texas experimental tokamak for the measurement of electron and ion temperatures from the Kα spectra of helium-like argon and its satellite lines. A two-dimensional multi-wire proportional counter has been applied to detect the spectra. The electron and ion temperatures have been obtained from the Voigt fitting with the spectra of helium-like argon ions. The profiles of electron and ion temperatures show the dependence on electron density in ohmic plasmas.

  8. Emittance study of a 28 GHz electron cyclotron resonance ion source for the Rare Isotope Science Project superconducting linear accelerator

    SciTech Connect

    Park, Bum-Sik Hong, In-Seok; Jang, Ji-Ho; Jin, Hyunchang; Choi, Sukjin; Kim, Yonghwan

    2016-02-15

    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.

  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.

  10. 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.

  11. 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

    2016-03-29

    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.

  12. 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).

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Deflection and Extraction of Pb Ions up to 33 TeV/c by a Bent Silicon Crystal

    SciTech Connect

    Arduini, G.; Biino, C.; Clement, M.; Cornelis, K.; Doble, N.; Elsener, K.; Ferioli, G.; Fidecaro, G.; Gatignon, L.; Grafstroem, P.; Gyr, M.; Herr, W.; Klem, J.; Mikkelsen, U.; Weisse, E.; Mo Uggerho Taratin, A.; Freund, A.; Keppler, P.; Major, J.

    1997-11-01

    The first results from an experiment to deflect a beam of fully stripped, ultrarelativistic Pb{sup 82+} ions of 400 GeV/c per unit of charge, equivalent to 33 TeV/c , by means of a bent crystal are reported. Deflection efficiencies are as high as 14{percent}, in agreement with theoretical estimates. In a second experiment a bent crystal was used to extract 270 GeV/c -per-charge Pb{sup 82+} (22 TeV/c) ions from a coasting beam in the CERN-SPS, and a high extraction efficiency of up to 10{percent} was found. These represent the first measurements to demonstrate applications of bent crystals in high energy heavy ion beams. {copyright} {ital 1997} {ital The American Physical Society}

  18. 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.

  19. Influence of yttrium content on the location of rare earth ions in LYSO:Ce crystals

    NASA Astrophysics Data System (ADS)

    Ding, Dongzhou; Weng, Linhong; Yang, Jianhua; Ren, Guohao; Wu, Yuntao

    2014-01-01

    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 (Lu1-xYx)2SiO5:Ce (x=0 at%, 8.7 at%, 25.7 at%, 44.7 at%, 65.7 at%, 87.9 at% and 100 at%). Y3+ 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 Ce3+ ion was discussed.

  20. 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.

  1. 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.

  2. 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

    2016-02-29

    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.

  3. Absorption spectra of vanadyl ion doped in MgNH 4PO 4·6H 2O (struvite) crystal

    NASA Astrophysics Data System (ADS)

    Agarwal, O. P.; Chand, Prem

    1984-10-01

    Results of Electron Paramagnetic Resonance (EPR) and optical absorption studies of VO 2+ ion doped in struvite at room liquid nitrogen temperatures are reported. Three preferential V= O bond directions in the crystal have been identified. The optical and EPR data have shown the formation of NH 4(PO 4VO(H 2O) 5 complex in the crystal as a result of VO 2+ doping. Correlating the optical and EPR data the molecular orbital coefficients are also obtained and discussed.

  4. Broadband and broadangle SPP antennas based on plasmonic crystals with linear chirp

    PubMed Central

    Bouillard, J.-S; Vilain, S.; Dickson, W.; Wurtz, G. A.; Zayats, A. V.

    2012-01-01

    Plasmonic technology relies on the coupling of light to surface electromagnetic modes on smooth or structured metal surfaces. While some applications utilise the resonant nature of surface polaritons, others require broadband characteristics. We demonstrate unidirectional and broadband plasmonic antennas with large acceptance angles based on chirped plasmonic gratings. Near-field optical measurements have been used to visualise the excitation of surface plasmon polaritons by such aperiodic structures. These weakly aperiodic plasmonic crystals allow the formation of a trapped rainbow-type effect in a two-dimensional geometry as surface polaritons of different frequencies are coherently excited in different locations over the plasmonic structure. Both the crystal's finite size and the finite lifetime of plasmonic states are crucial for the generation of broadband surface plasmon polaritons. This approach presents new opportunities for building unidirectional, broadband and broad-angle plasmonic couplers for sensing purposes, information processing, photovoltaic applications and shaping and manipulating ultrashort optical pulses. PMID:23170197

  5. Anisotropic crystallization in solution processed chalcogenide thin film by linearly polarized laser

    NASA Astrophysics Data System (ADS)

    Gu, Tingyi; Jeong, Hyuncheol; Yang, Kengran; Wu, Fan; Yao, Nan; Priestley, Rodney D.; White, Claire E.; Arnold, Craig B.

    2017-01-01

    The low activation energy associated with amorphous chalcogenide structures offers broad tunability of material properties with laser-based or thermal processing. In this paper, we study near-bandgap laser induced anisotropic crystallization in solution processed arsenic sulfide. The modified electronic bandtail states associated with laser irradiation lead to a distinctive photoluminescence spectrum, compared to thermally annealed amorphous glass. Laser crystalized materials exhibit a periodic subwavelength ripple structure in transmission electron microscopy experiments and show polarization dependent photoluminescence. Analysis of the local atomic structure of these materials using laboratory-based X-ray pair distribution function analysis indicates that laser irradiation causes a slight rearrangement at the atomic length scale, with a small percentage of S-S homopolar bonds converting to As-S heteropolar bonds. These results highlight fundamental differences between laser and thermal processing in this important class of materials.

  6. Two active site divalent ions in the crystal structure of the hammerhead ribozyme bound to a transition state analogue

    SciTech Connect

    Mir, Aamir; Golden, Barbara L.

    2015-11-09

    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. Finally, on the basis of this crystal structure as well as a wealth of biochemical studies, in this paper we propose a mechanism in which G12 serves as the general base and a magnesium-bound water serves as a general acid.

  7. 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.

  8. Defect structures and optical characteristics of Er3+ ion in Er:LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Qian, Yannan; Wang, Rui; Wang, Biao; Xu, Chao; Xing, Lili; Xu, Yanling

    2013-03-01

    Congruent Er:LiNbO3 crystals were grown by Czochraski method. The OH- absorption and UV-vis-near infrared absorption spectra indicated that Er3+ cluster sites were formed in LiNbO3 crystal doped with 3 mol% Er3+ ions. Studies on the stokes and anti-stokes spectra showed that the formation of Er3+ cluster sites could increase the rate of cross relaxation processes. Judd-Ofelt theory was carried out to discuss the spectral characteristics of Er3+ ions in Er:LiNbO3 crystals. Based on Füchtbauer-Ladenburg and McCumber theory, the emission cross section of the 4I13/2 → 4I15/2 transition of Er3+ ion was calculated, and the potential laser performance was evaluated by the gain cross section spectra. Er:LiNbO3 crystal codoped with Zn2+ ions was also grown to discuss the relation between the defect structure and optical characteristics of Er3+ ion.

  9. 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.

  10. 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.

  11. Supercharging with m-nitrobenzyl alcohol and propylene carbonate: forming highly charged ions with extended, near-linear conformations.

    PubMed

    Going, Catherine C; Williams, Evan R

    2015-04-07

    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.

  12. 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

    2016-08-09

    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

  13. A quasi-linear theory to explain ion acceleration in the distant cometary environment

    NASA Technical Reports Server (NTRS)

    Sinha, Raji; Gary, S. Peter; Roderick, Norman

    1990-01-01

    Spacecraft observations at comet Halley as well as computer simulations have shown that pitch angle scattering of newborn cometary ions proceeds at a relatively fast rate, leading to relatively isotropic shell-like velocity distribution functions. Energization processes whereby shell distributions become more Maxwellian and a few ions are accelerated to high energies appear to proceed more slowly. The research on the latter, slower process is described, in which the scattering is assumed to be due to the resonant, growing magnetic fluctuations driven by the non-Maxwellian nature of the ion distribution. An ion shell distribution which is isotropic in the wave frame begins the process and a Fokker-Plank derived from quasilinear plasma theory is used to describe the broadening and energization of the cometary ion distribution.

  14. Growth, structural, optical and electrical behavior of glycine potassium nitrate (GPN) crystal with non-linear optical response

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

    New trapezoidal, non-linear optical crystals of glycine potassium nitrate (GPN) have been grown by slow cooling from solutions with an initial pH of 4.3. Chemical composition, phase formation and functional groups have been verified by CHN, EDAX, XRF, NMR, XRD, FTIR and Raman studies. UV studies show a much lower cut off wavelength (195 nm) compared to the much investigated glycine sodium nitrate (GSN). The powder SHG efficiency of GPN is found to be 0.6 times compared to that of potassium dihydrogen phosphate (KDP). Cut and polished crystals exposed to light indicate positive photoconductivity. Electrical conductivity studies show an activation energy of 0.16 eV and the dielectric loss is found to decay drastically at higher frequencies (1 MHz) which is desirable in electronic applications. Vickers microhardness studies indicate a Mayer's index value of 2.78. Well resolved, elongated and oriented etch pits have been observed on the side habit face (220) treated in glacial acetic acid for 5 s. Typical circular features resisting the formation of etch pits representing impurity elements have been observed on the cleavage faces. Moisture has been traced on the surface of the crystals subjected to heat treatment.

  15. Superhyperfine structure in the EPR spectra and optical spectra of impurity f ions in dielectric crystals: A review

    NASA Astrophysics Data System (ADS)

    Aminov, L. K.; Kurkin, I. N.; Malkin, B. Z.

    2013-07-01

    The results of observation and simulation of the superhyperfine (ligand hyperfine) structure (SHFS) of the electron paramagnetic resonance (EPR) spectra of rare-earth and uranium impurity ions in dielectric crystals have been systematized. The resolved SHFS of the EPR spectra of doped cubic crystals (with the fluorite and perovskite structures) has been observed for orientations of a constant magnetic field along the crystallographic axes. Most attention has been paid to tetragonal double fluorides Li RF4 ( R = Y, Lu, Tm), in which the SHFS of the EPR spectra has also been found for intermediate orientations of the magnetic field. For the LiYF4: Nd3+ single crystal, the splitting of optical spectral lines due to the interaction of Nd3+ ions with nuclear magnetic moments of the nearest neighbor fluorine ions has been observed for the first time. The Van Vleck paramagnet LiTmF4: U3+ is characterized by the SHFS with clearly distinguishable components due to the interaction of uranium ions both with nuclei of the fluorine ions and with enhanced magnetic moments of the thulium nuclei. The SHFS envelopes of the EPR spectra of Yb3+, Ce3+, Nd3+, and U3+ ions in LiYF4 and LiLuF4 crystals are well reproduced by numerical calculations based on the microscopic model using only three fitting parameters: the width of transitions between the electron-nuclear sublevels of the complex containing the paramagnetic ion and nuclei of the ligands and two constants of covalent bonding of the f electrons with 2 s and 2 p electrons of the nearest neighbor fluorine ions.

  16. Negative Ion Crystal Formation in Nonequilibrium Dusty Plasma at a Gas Evacuation from Technological Devices for Vacuum Support

    NASA Astrophysics Data System (ADS)

    Azarenkov, Nikolai A.; Egorov, Alexei M.; Maslov, Vasyl I.; Onishchenko, Ivan N.; Frolova, Darya Yu.

    2002-11-01

    Plasma crystal formation (or so called ion crystal formation) are investigated now intensively (see, for example, [1-5]). In particular, the formation of the plasma crystals has been observed in experiments at providing of nonequilibrium state. If in equilibrium dusty plasma there was no plasma crystal but at providing of nonequilibrium state at a gas evacuation from devices for vacuum support in a dusty plasma in experiment an ion crystal has been formed. In this case at gas evacuation the plasma flow has been appeared due to gradient of the pressure. The flow excites the perturbations of large amplitudes. The generalised equation is derived for the spatial distribution of field of any amplitude. It is shown that these perturbations of large amplitude lead to spatial ordering of heavy negative ions. It is shown that the crystal is almost motionless, because heavy negative ions are trapped by chain of perturbations formed due to instability development on generalised dusty-ion-acoustic mode with velocity equal almost zero. 1.H.M.Thomas, G.E. Morfill. Nature. 379 (1996) 806. 2.R.K.Varma, P.K.Shukla. Physica Scripta. 51 (1995) 522. 3.M.Nambu, S.V.Vladimirov, P.K.Shukla. Phys. Lett. A. 203 (1995) 40. 4.A.Melzer, A.Piel et al. Proc. Int. Top. Conf. on Plasma Physics. Trieste. Italy. 2000. 5.V.E.Fortov, A.P.Nefedov et al. Proc. Int. Conf. on Plasma Physics. Trieste. Italy. 2000. 6.D.A.Law, B.M.Annaratone, J.E.Allen et al. Dust Particle Interaction in RF Plasma Sheaths.

  17. Tunable broadband isolator based on electro-optically induced linear gratings in a nonlinear photonic crystal.

    PubMed

    Yu, Zi-Yan; Xu, Fei; Lin, Xiao-Wen; Song, Xiao-Shi; Qian, Xiao-Shi; Wang, Qin; Lu, Yan-Qing

    2010-10-15

    We theoretically propose a broadband optical isolator based on second-harmonic generation in a one-dimensional quadratic nonlinear photonic crystal (NPC) with an embedded defect. An external electric field along the z axis is applied to modulate the NPC refractive index periodically. Complete optical isolation always could be reached with the help of an external field. Influences of the defect position and thickness are discussed. The spectral and power tolerances of the isolator also have been investigated and show high contrast within a wide wavelength range at different power levels.

  18. Sealing glass-ceramics with near-linear thermal strain, Part II: Sequence of crystallization and phase stability

    SciTech Connect

    Rodriguez, Mark A.; Griego, James J. M.; Dai, Steve

    2016-08-22

    The sequence of crystallization in a recrystallizable lithium silicate sealing glass-ceramic Li2O–SiO2–Al2O3–K2O–B2O3–P2O5–ZnO was analyzed by in situ high-temperature X-ray diffraction (HTXRD). Glass-ceramic specimens have been subjected to a two-stage heat-treatment schedule, including rapid cooling from sealing temperature to a first hold temperature 650°C, followed by heating to a second hold temperature of 810°C. Notable growth and saturation of Quartz was observed at 650°C (first hold). Cristobalite crystallized at the second hold temperature of 810°C, growing from the residual glass rather than converting from the Quartz. The coexistence of quartz and cristobalite resulted in a glass-ceramic having a near-linear thermal strain, as opposed to the highly nonlinear glass-ceramic where the cristobalite is the dominant silica crystalline phase. HTXRD was also performed to analyze the inversion and phase stability of the two types of fully crystallized glass-ceramics. While the inversion in cristobalite resembles the character of a first-order displacive phase transformation, i.e., step changes in lattice parameters and thermal hysteresis in the transition temperature, the inversion in quartz appears more diffuse and occurs over a much broader temperature range. Furthermore, localized tensile stresses on quartz and possible solid-solution effects have been attributed to the transition behavior of quartz crystals embedded in the glass-ceramics.

  19. Sealing glass-ceramics with near-linear thermal strain, Part II: Sequence of crystallization and phase stability

    DOE PAGES

    Rodriguez, Mark A.; Griego, James J. M.; Dai, Steve

    2016-08-22

    The sequence of crystallization in a recrystallizable lithium silicate sealing glass-ceramic Li2O–SiO2–Al2O3–K2O–B2O3–P2O5–ZnO was analyzed by in situ high-temperature X-ray diffraction (HTXRD). Glass-ceramic specimens have been subjected to a two-stage heat-treatment schedule, including rapid cooling from sealing temperature to a first hold temperature 650°C, followed by heating to a second hold temperature of 810°C. Notable growth and saturation of Quartz was observed at 650°C (first hold). Cristobalite crystallized at the second hold temperature of 810°C, growing from the residual glass rather than converting from the Quartz. The coexistence of quartz and cristobalite resulted in a glass-ceramic having a near-linear thermal strain,more » as opposed to the highly nonlinear glass-ceramic where the cristobalite is the dominant silica crystalline phase. HTXRD was also performed to analyze the inversion and phase stability of the two types of fully crystallized glass-ceramics. While the inversion in cristobalite resembles the character of a first-order displacive phase transformation, i.e., step changes in lattice parameters and thermal hysteresis in the transition temperature, the inversion in quartz appears more diffuse and occurs over a much broader temperature range. Furthermore, localized tensile stresses on quartz and possible solid-solution effects have been attributed to the transition behavior of quartz crystals embedded in the glass-ceramics.« less

  20. Compositional investigation of liquid crystal alignment on tantalum oxide via ion beam irradiation

    SciTech Connect

    Kim, Jong-Yeon; Oh, Byeong-Yun; Kim, Byoung-Yong; Kim, Young-Hwan; Han, Jin-Woo; Han, Jeong-Min; Seo, Dae-Shik

    2008-01-28

    The homogeneously aligned liquid crystal display on Ta{sub 2}O{sub 5} via ion beam (IB) irradiation was first embodied with controllability of pretilt angle depending on incident angle of the IB. As a result of x-ray photoelectron spectroscopic analysis, the intensity of Ta-O and O-Ta bondings as a function of incident angle behaved reversely with the pretilt angle and the lowest amplitude was observed at 45 deg. It revealed that the creation of pretilt angle was attributed to the irradiation of the IB by breaking Ta-O and O-Ta bonding so orientational order was generated by directional IB. Comparable electro-optical characteristics to rubbed polyimide were also achieved.

  1. Silver Ions Direct Twin-Plane Formation during the Overgrowth of Single-Crystal Gold Nanoparticles

    PubMed Central

    2016-01-01

    It is commonly agreed that the crystalline structure of seeds dictates the crystallinity of final nanoparticles in a seeded-growth process. Although the formation of monocrystalline particles does require the use of single-crystal seeds, twin planes may stem from either single- or polycrystalline seeds. However, experimental control over twin-plane formation remains difficult to achieve synthetically. Here, we show that a careful interplay between kinetics and selective surface passivation offers a unique handle over the emergence of twin planes (in decahedra and triangles) during the growth over single-crystalline gold nanoparticles of quasi-spherical shape. Twinning can be suppressed under conditions of slow kinetics in the presence of silver ions, yielding single-crystalline particles with high-index facets. PMID:27656688

  2. 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.

  3. Structural recovery in plastic crystals by time-resolved non-linear dielectric spectroscopy.

    PubMed

    Riechers, Birte; Samwer, Konrad; Richert, Ranko

    2015-04-21

    The dielectric relaxation of several different plastic crystals has been examined at high amplitudes of the ac electric fields, with the aim of exploring possible differences with respect to supercooled liquids. In all cases, the steady state high field loss spectrum appears to be widened, compared with its low field limit counterpart, whereas peak position and peak amplitude remain almost unchanged. This field induced change in the loss profile is explained on the basis of two distinct effects: an increased relaxation time due to reduced configurational entropy at high fields which affects the low frequency part of the spectrum, and accelerated dynamics at frequencies above the loss peak position resulting from the added energy that the sample absorbs from the external electric field. From the time-resolved assessment of the field induced changes in fictive temperatures at relatively high frequencies, we find that this structural recovery is slaved to the average rather than mode specific structural relaxation time. In other words, the very fast relaxation modes in the plastic crystal cannot adjust their fictive temperatures faster than the slower modes, the equivalent of time aging-time superposition. As a result, an explanation for this single fictive temperature must be consistent with positional order, i.e., translational motion or local density fluctuations do not govern the persistence time of local time constants.

  4. 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

  5. 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.

  6. 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.

  7. Strain profiles in ion implanted ceramic polycrystals: An approach based on reciprocal-space crystal selection

    SciTech Connect

    Palancher, H. Martin, G.; Fouet, J.; Goudeau, P.; Boulle, A.; Rieutord, F.; Favre-Nicolin, V.; Blanc, N.; Onofri, C.

    2016-01-18

    The determination of the state of strain in implanted materials is a key issue in the study of their mechanical stability. Whereas this question is nowadays relatively easily solved in the case of single crystals, it remains a challenging task in the case of polycrystalline materials. In this paper, we take benefit of the intense and parallel beams provided by third generation synchrotron sources combined with a two-dimensional detection system to analyze individual grains in polycrystals, hence obtaining “single crystal-like” data. The feasibility of the approach is demonstrated with implanted UO{sub 2} polycrystals where the in-depth strain profile is extracted for individual grains using numerical simulations of the diffracted signal. The influence of the implantation dose is precisely analyzed for several diffracting planes and grains. This work suggests that, at low fluences, the development of strain is mainly due to ballistic effects with little effect from He ions, independently from the crystallographic orientation. At higher fluences, the evolution of the strain profiles suggests a partial and anisotropic plastic relaxation. With the present approach, robust and reliable structural information can be obtained, even from complex polycrystalline ceramic materials.

  8. Application of electrochemical quartz crystal microbalance to lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Kwon, Kyungjung

    An electrochemical quartz crystal microbalance (EQCM) was used in an investigation of the corrosion of aluminum and of the formation of the solid electrolyte interphase (SEI) on carbon in electrolytes appropriate for lithium-ion batteries. Aluminum corrosion in some electrolytes such as LiN(CF3SO 2)2/propylene carbonate was examined and a corrosion mechanism was suggested. The behavior of the carbon electrode in LiClO4 or LiPF 6/EC+DMC was examined by combining electrochemical methods with EQCM. A difficulty encountered in this use of the EQCM was a monotonic decrease in crystal resonant frequency with time. It was determined that this was due to a change in the viscosity of the electrolyte. Viscosities of some electrolytes that contained ethylene carbonate (EC) and dimethyl carbonate (DMC) were measured and they increased when in contact with carbon, nickel, and aluminum electrodes but did not change with time when stored in glass vials. The SO density in LiClO4/EC+DMC was estimated to be about 1.3 g/cm3 by combining the EQCM and ellipsometry.

  9. 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

  10. Strain profiles in ion implanted ceramic polycrystals: An approach based on reciprocal-space crystal selection

    NASA Astrophysics Data System (ADS)

    Palancher, H.; Goudeau, P.; Boulle, A.; Rieutord, F.; Favre-Nicolin, V.; Blanc, N.; Martin, G.; Fouet, J.; Onofri, C.

    2016-01-01

    The determination of the state of strain in implanted materials is a key issue in the study of their mechanical stability. Whereas this question is nowadays relatively easily solved in the case of single crystals, it remains a challenging task in the case of polycrystalline materials. In this paper, we take benefit of the intense and parallel beams provided by third generation synchrotron sources combined with a two-dimensional detection system to analyze individual grains in polycrystals, hence obtaining "single crystal-like" data. The feasibility of the approach is demonstrated with implanted UO2 polycrystals where the in-depth strain profile is extracted for individual grains using numerical simulations of the diffracted signal. The influence of the implantation dose is precisely analyzed for several diffracting planes and grains. This work suggests that, at low fluences, the development of strain is mainly due to ballistic effects with little effect from He ions, independently from the crystallographic orientation. At higher fluences, the evolution of the strain profiles suggests a partial and anisotropic plastic relaxation. With the present approach, robust and reliable structural information can be obtained, even from complex polycrystalline ceramic materials.

  11. 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

  12. Linear rate-equilibrium relations arising from ion channel-bilayer energetic coupling

    PubMed Central

    Greisen, Per; Lum, Kevin; Ashrafuzzaman, Md.; Greathouse, Denise V.; Andersen, Olaf S.; Lundbæk, Jens A.

    2011-01-01

    Linear rate-equilibrium (RE) relations, also known as linear free energy relations, are widely observed in chemical reactions, including protein folding, enzymatic catalysis, and channel gating. Despite the widespread occurrence of linear RE relations, the principles underlying the linear relation between changes in activation and equilibrium energy in macromolecular reactions remain enigmatic. When examining amphiphile regulation of gramicidin channel gating in lipid bilayers, we noted that the gating process could be described by a linear RE relation with a simple geometric interpretation. This description is possible because the gating process provides a well-understood reaction, in which structural changes in a bilayer-embedded model protein can be studied at the single-molecule level. It is thus possible to obtain quantitative information about the energetics of the reaction transition state and its position on a spatial coordinate. It turns out that the linear RE relation for the gramicidin monomer-dimer reaction can be understood, and the quantitative relation between changes in activation energy and equilibrium energy can be interpreted, by considering the effects of amphiphiles on the changes in bilayer elastic energy associated with channel gating. We are not aware that a similar simple mechanistic explanation of a linear RE relation has been provided for a chemical reaction in a macromolecule. RE relations generally should be useful for examining how amphiphile-induced changes in bilayer properties modulate membrane protein folding and function, and for distinguishing between direct (e.g., due to binding) and indirect (bilayer-mediated) effects. PMID:21768343

  13. Relation between ligand design and transition energy for the praseodymium ion in crystals.

    PubMed

    Zhou, Xianju; Tanner, Peter A

    2015-01-08

    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.

  14. 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

    2016-06-14

    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.

  15. 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.

  16. 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

  17. 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.

  18. Pulse height reduction effects of single-crystal CVD diamond detector for low-energy heavy ions

    NASA Astrophysics Data System (ADS)

    Sato, Y.; Shimaoka, T.; Kaneko, J. H.; Murakami, H.; Miyazaki, D.; Tsubota, M.; Chayahara, A.; Umezawa, H.; Shikata, S.

    2013-10-01

    The performance of a diamond detector made of single-crystal diamond grown by chemical vapour deposition was studied for heavy ions, having energy of 3 MeV. Energy peaks of these low-energy ions were clearly observed. However, the pulse height for individual incident ion decreases with increasing atomic number of the ions. For understanding this pulse height reduction effect, we calculated the amount of ionizing and non-ionizing energy loss of incident ions in the diamond detector. The results of our calculation suggest the contribution of charge loss mechanisms other than the recombination effect of electron-hole pairs produced along the ionized track. We also mentioned the incomplete charge collection near the boundary region between the metal electrode and the diamond surface.

  19. Comparison of kinetic and extended magnetohydrodynamics computational models for the linear ion temperature gradient instability in slab geometry

    NASA Astrophysics Data System (ADS)

    Schnack, D. D.; Cheng, J.; Barnes, D. C.; Parker, S. E.

    2013-06-01

    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∥/k⊥≪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 LTi0, instability requires that either k⊥ρi or ρi/LTi0 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 =ωr+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⊥ρi and ρi/LTi0 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⊥ρi or ρi/LTi0 increases. There is good qualitative agreement between the models for the shape of the unstable global eigenfunction for LTi0/ρi=30 and 20. The results quantify how far fluid calculations can be extended accurately into the kinetic regime. We conclude that for the linear ITG

  20. Crystal structure, vibrational properties and luminescence of NaMg{sub 3}Al(MoO{sub 4}){sub 5} crystal doped with Cr{sup 3+} ions

    SciTech Connect

    Hermanowicz, K.; Maczka, M. . E-mail: m.maczka@int.pan.wroc.pl; Wolcyrz, M.; Tomaszewski, P.E.; Pasciak, M.; Hanuza, J.

    2006-03-15

    Crystals of NaMg{sub 3}Al(MoO{sub 4}){sub 5} doped with 0.5% Cr{sup 3+} ions have been synthesized and characterized by a single-crystal X-ray structure analysis and IR, Raman, electron absorption and luminescence spectroscopic studies. It has been shown that NaMg{sub 3}Al(MoO{sub 4}){sub 5} crystallizes in the P1-bar structure, with a=6.8744(8) A, b=6.9342(7) A, c=17.605(2) A, {alpha}=87.788(8){sup o}, {beta}=87.727(9){sup o}, {gamma}=78.501(9){sup o}, Z=2. The characteristic feature of the structure is its enormously large thermal displacement parameter for sodium, even at 105K. The IR and Raman spectra indicate significant interactions between the MoO{sub 4}{sup 2-} ions in the structure. The electron absorption, excitation and luminescence studies have shown that there are at least two different sites of incorporated Cr{sup 3+} ions in the NaMg{sub 3}Al(MoO{sub 4}){sub 5} crystal structure. They differ themselves by strength of crystalline field. One of them is characterized by Cr{sup 3+} in low ligand field and {sup 4}T{sub 2}->{sup 4}A{sub 2} emission whereas the second is characterized by higher strength of the crystal field and dominant {sup 2}E->{sup 4}A{sub 2} emission. Temperature-dependent studies show that the compound does not exhibit any phase transition.0.

  1. 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.

  2. Optical and mechanical properties of MgO crystals implanted with lithium ions

    NASA Astrophysics Data System (ADS)

    Savoini, B.; Cáceres, D.; Vergara, I.; González, R.; da Silva, R. C.; Alves, E.; Chen, Y.

    2004-03-01

    Defect profile induced by implantation of Li+ ions with an energy of 175 keV and a fluence of 1×1017ions/cm2 in MgO single crystals was characterized by Rutherford backscattering and optical absorption measurements. Several absorption bands at 5.0, 3.49, 2.16, and 1.27 eV, identical to those found in neutron irradiated crystals, were observed and have been previously associated with oxygen vacancies and higher-order point defects involving oxygen vacancies. Despite the high fluence of Li+ ions, no evidence was found for the formation of Li nanocolloids during implantation. Nanoindentation experiments demonstrated that both the hardness and Young's modulus were higher in the implanted layer than in the sample before implantation. The maximum values were H=(17.4±0.4) and E=(358±9) GPa, respectively, at a contact depth of ≈165 nm. Thermal annealings in flowing argon at increasing temperatures improved the crystalline quality of the implanted layer. After annealing at 500 K, two extinction bands at ≈2.75 and 3.80 eV emerged. These bands are attributed to Mie scattering from metallic lithium nanocolloids with either a face-centered- or a body-centered-cubic structure. The latter band was almost absent by 950 K. The former reached a maximum intensity after the thermal treatment at 1050 K and disappeared by 1250 K. The behavior of these bands can be satisfactorily explained by the Maxwell-Garnett theory. The decrease in hardening cannot be correlated with the thermal destruction of the absorption bands at 5.0, 3.49, 2.16, and 1.27 eV, but rather with the annihilation of both lithium and oxygen interstitials. Lithium outdiffusion from the implanted region takes place at temperatures of ≈1100 K. It is concluded that the hardening observed in the implanted region was primarily due to the extraordinarily large concentration of both lithium and oxygen interstitials.

  3. 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.

  4. Ion bombardment induced buried lateral growth: the key mechanism for the synthesis of single crystal diamond wafers

    PubMed Central

    Schreck, Matthias; Gsell, Stefan; Brescia, Rosaria; Fischer, Martin

    2017-01-01

    A detailed mechanism for heteroepitaxial diamond nucleation under ion bombardment in a microwave plasma enhanced chemical vapour deposition setup on the single crystal surface of iridium is presented. The novel mechanism of Ion Bombardment Induced Buried Lateral Growth (IBI-BLG) is based on the ion bombardment induced formation and lateral spread of epitaxial diamond within a ~1 nm thick carbon layer. Starting from one single primary nucleation event the buried epitaxial island can expand laterally over distances of several microns. During this epitaxial lateral growth typically thousands of isolated secondary nuclei are generated continuously. The unique process is so far only observed on iridium surfaces. It is shown that a diamond single crystal with a diameter of ~90 mm and a weight of 155 carat can be grown from such a carbon film which initially consisted of 2 · 1013 individual grains. PMID:28294167

  5. Ion bombardment induced buried lateral growth: the key mechanism for the synthesis of single crystal diamond wafers

    NASA Astrophysics Data System (ADS)

    Schreck, Matthias; Gsell, Stefan; Brescia, Rosaria; Fischer, Martin

    2017-03-01

    A detailed mechanism for heteroepitaxial diamond nucleation under ion bombardment in a microwave plasma enhanced chemical vapour deposition setup on the single crystal surface of iridium is presented. The novel mechanism of Ion Bombardment Induced Buried Lateral Growth (IBI-BLG) is based on the ion bombardment induced formation and lateral spread of epitaxial diamond within a ~1 nm thick carbon layer. Starting from one single primary nucleation event the buried epitaxial island can expand laterally over distances of several microns. During this epitaxial lateral growth typically thousands of isolated secondary nuclei are generated continuously. The unique process is so far only observed on iridium surfaces. It is shown that a diamond single crystal with a diameter of ~90 mm and a weight of 155 carat can be grown from such a carbon film which initially consisted of 2 · 1013 individual grains.

  6. 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

  7. 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.

  8. 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.

  9. Full characterization of laser-accelerated ion beams using Faraday cup, silicon carbide, and single-crystal diamond detectors

    NASA Astrophysics Data System (ADS)

    Margarone, D.; Krása, J.; Giuffrida, L.; Picciotto, A.; Torrisi, L.; Nowak, T.; Musumeci, P.; Velyhan, A.; Prokůpek, J.; Láska, L.; Mocek, T.; Ullschmied, J.; Rus, B.

    2011-05-01

    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.

  10. In situ hydrothermal crystallization of hexagonal hydroxyapatite tubes from yttrium ion-doped hydroxyapatite by the Kirkendall effect.

    PubMed

    Li, Chengfeng; Ge, Xiaolu; Li, Guochang; Lu, Hao; Ding, Rui

    2014-12-01

    An in situ hydrothermal crystallization method with presence of glutamic acid, urea and yttrium ions was employed to fabricate hexagonal hydroxyapatite (HAp, Ca5(PO4)3(OH)) tubes with length of 200 nm-1 μm. Firstly, yttrium ion-doped HAp (Y-HAp, Ca(5-x)Y(x)(PO4)3(OH)) was synthesized after hydrolysis of urea and HPO4(2-) ions at 100°C with a dwell time of 24h. The shift of X-ray diffraction peaks of HAp to high angle was caused the substitution of Ca(2+) ions by small-sized Y(3+) ions. At 160°C, further hydrolysis reactions of urea and HPO4(2-) ions resulted in the generation of ample OH(-) and PO4(3-) ions, which provided a high chemical potential for the dissolution of Y-HAp and recrystallization of HAp and YPO4. Finally, HAp tubes were formed in situ on Y-HAp according to the Kirkendall effect as a result of the difference of diffusion rate of cations (Ca(2+) ions, outward and slow) and anions (OH(-) and PO4(3-) ions, inward and fast). The formation process of HAp tube was simulated by the encapsulation of fluorescein molecules in precipitates. Photoluminescence properties were enhanced for HAp tubes with thick and dense walls. This novel tubular material could find wide applications as carriers of drugs, dyes and catalysts.

  11. Ozone-induced dissociation on a modified tandem linear ion-trap: observations of different reactivity for isomeric lipids.

    PubMed

    Poad, Berwyck L J; Pham, Huong T; Thomas, Michael C; Nealon, Jessica R; Campbell, J Larry; Mitchell, Todd W; Blanksby, Stephen J

    2010-12-01

    Ozone-induced dissociation (OzID) exploits the gas-phase reaction between mass-selected lipid ions and ozone vapor to determine the position(s) of unsaturation. In this contribution, we describe the modification of a tandem linear ion-trap mass spectrometer specifically for OzID analyses wherein ozone vapor is supplied to the collision cell. This instrumental configuration provides spatial separation between mass-selection, the ozonolysis reaction, and mass-analysis steps in the OzID process and thus delivers significant enhancements in speed and sensitivity (ca. 30-fold). These improvements allow spectra revealing the double-bond position(s) within unsaturated lipids to be acquired within 1 s: significantly enhancing the utility of OzID in high-throughput lipidomic protocols. The stable ozone concentration afforded by this modified instrument also allows direct comparison of relative reactivity of isomeric lipids and reveals reactivity trends related to (1) double-bond position, (2) substitution position on the glycerol backbone, and (3) stereochemistry. For cis- and trans-isomers, differences were also observed in the branching ratio of product ions arising from the gas-phase ozonolysis reaction, suggesting that relative ion abundances could be exploited as markers for double-bond geometry. Additional activation energy applied to mass-selected lipid ions during injection into the collision cell (with ozone present) was found to yield spectra containing both OzID and classical-CID fragment ions. This combination CID-OzID acquisition on an ostensibly simple monounsaturated phosphatidylcholine within a cow brain lipid extract provided evidence for up to four structurally distinct phospholipids differing in both double-bond position and sn-substitution.

  12. 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

  13. Growth, spectral, linear and nonlinear optical characteristics of an efficient semiorganic acentric crystal: L-valinium L-valine chloride

    NASA Astrophysics Data System (ADS)

    Nageshwari, M.; Jayaprakash, P.; Kumari, C. Rathika Thaya; Vinitha, G.; Caroline, M. Lydia

    2017-04-01

    An efficient nonlinear optical semiorganic material L-valinium L-valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P21. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59 GW/cm2. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics.

  14. Advanced Resolution Organic Molecule Analyzer (AROMA): Simulations, Development and Initial Testing of a Linear Ion Trap-Orbitrap Instrument for Space

    NASA Astrophysics Data System (ADS)

    Arevalo, R.; Danell, R. M.; Gundersen, C.; Hovmand, L.; Southard, A.; Tan, F.; Grubisic, A.; Brinckerhoff, W. B.; Getty, S. A.; Mahaffy, P.; Cottin, H.; Briois, C.; Colin, F.; Szopa, C.; Vuitton, V.; Makarov, A.; Reinhardt-Szyba, M.

    2016-10-01

    AROMA combines a linear ion trap and Orbitrap mass analyzer to enable: quantitative measurements of organic and inorganic compounds; selective isolation of targeted mass ranges; tandem mass spectrometry; and, ultrahigh mass resolution and accuracy.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Quantitative comparison of a flared and a standard heated metal capillary inlet with a voltage-assisted air amplifier on an electrospray ionization linear ion trap mass spectrometer.

    PubMed

    Dixon, R Brent; Muddiman, David C

    2007-01-01

    The performance characteristics (i.e., ion abundance and electrospray ion current) of a flared and blunt-ended heated metal capillary were evaluated with a voltage-assisted air amplifier on a linear ion trap mass spectrometer (LTQ-MS). The results demonstrated that a standard capillary afforded higher ion abundance than a flared capillary, thus further work is necessary to investigate conditions for which significant benefits with the flared capillary will be observed. The compatibility of a voltage-assisted air amplifier is explored for both types of capillaries and in all cases resulted in improved ion abundance and spray current.

  3. 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.

  4. Laser induced fluorescence measurements of axial velocity, velocity shear, and parallel ion temperature profiles during the route to plasma turbulence in a linear magnetized plasma device

    NASA Astrophysics Data System (ADS)

    Chakraborty Thakur, S.; Adriany, K.; Gosselin, J. J.; McKee, J.; Scime, E. E.; Sears, S. H.; Tynan, G. R.

    2016-11-01

    We report experimental measurements of the axial plasma flow and the parallel ion temperature in a magnetized linear plasma device. We used laser induced fluorescence to measure Doppler resolved ion velocity distribution functions in argon plasma to obtain spatially resolved axial velocities and parallel ion temperatures. We also show changes in the parallel velocity profiles during the transition from resistive drift wave dominated plasma to a state of weak turbulence driven by multiple plasma instabilities.

  5. Crystal structures and redox responses coupled with ion recognition of p-benzoquinone- and hydroquinone-fused [18]crown-6.

    PubMed

    Kobayashi, Takayuki; Nakane, Yuta; Takeda, Takashi; Hoshino, Norihisa; Kawai, Hidetoshi; Akutagawa, Tomoyuki

    2015-02-01

    The crystal structures and redox properties of p-benzoquinone (BQ)-fused [18]crown-6 1 and bis-BQ-fused [18]crown-6 2 were examined. The anion radicals of these BQ molecules were stabilized by addition of metal ions, through effective electrostatic interactions between the negatively charged BQ moiety and positively charged ion-capturing [18]crown-6 unit. The electrostatic interactions and solvation energy played important roles in determining the magnitudes of anodic redox shifts in the reduction potentials. Regular π-stacking of BQ units and regular arrays of [18]crown-6 units were observed in crystal 2, in which one-dimensional π-electron columns were separated by ionic channels. The hydroquinone-fused [18]crown-6 molecule 3 and a new BQ- and phenol-fused [18]crown-6 derivative 4 were obtained as single crystals. The molecular conformations of [18]crown-6 in crystal 3 and hydrated crystal 3⋅H2 O were different from each other.

  6. 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.

  7. Crystal structure of a SLC11 (NRAMP) transporter reveals the basis for transition-metal ion transport.

    PubMed

    Ehrnstorfer, Ines A; Geertsma, Eric R; Pardon, Els; Steyaert, Jan; Dutzler, Raimund

    2014-11-01

    Members of the SLC11 (NRAMP) family transport iron and other transition-metal ions across cellular membranes. These membrane proteins are present in all kingdoms of life with a high degree of sequence conservation. To gain insight into the determinants of ion selectivity, we have determined the crystal structure of Staphylococcus capitis DMT (ScaDMT), a close prokaryotic homolog of the family. ScaDMT shows a familiar architecture that was previously identified in the amino acid permease LeuT. The protein adopts an inward-facing conformation with a substrate-binding site located in the center of the transporter. This site is composed of conserved residues, which coordinate Mn2+, Fe2+ and Cd2+ but not Ca2+. Mutations of interacting residues affect ion binding and transport in both ScaDMT and human DMT1. Our study thus reveals a conserved mechanism for transition-metal ion selectivity within the SLC11 family.

  8. Two active site divalent ions in the crystal structure of the hammerhead ribozyme bound to a transition state analogue

    DOE PAGES

    Mir, Aamir; Golden, Barbara L.

    2015-11-09

    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. Finally, on the basis of this crystalmore » structure as well as a wealth of biochemical studies, in this paper we propose a mechanism in which G12 serves as the general base and a magnesium-bound water serves as a general acid.« less

  9. Investigation of Nd3+ ions spectroscopic and laser properties in SrF2 fluoride single crystal

    NASA Astrophysics Data System (ADS)

    Alimov, O. K.; Basiev, T. T.; Doroshenko, M. E.; Fedorov, P. P.; Konyushkin, V. A.; Nakladov, A. N.; Osiko, V. V.

    2012-03-01

    The laser properties of SrF2:Nd3+ crystal with neodymium ions concentration of 0.5 at.% were investigated under diode laser pumping. Using temperature tuning of laser diode pumping wavelength two different lines centered at about 1037 nm and 1044 nm attributed to oscillation of different optical centers were obtained. The maximum lasing slope efficiency of 37% was obtained. The absorption and fluorescence spectra of different individual and clustered Nd3+ ions optical centers were observed depending on Nd3+ concentration. The lifetimes of the high symmetry L-centers were measured and found to be two orders of magnitude longer than that for clustered M-centers at room temperature. The lifetimes of M-centers at different temperatures were measured and microparameter of ion-ion interaction in Nd-pairs was determined.

  10. N-Methylformamide as a Source of Methylammonium Ions in the Synthesis of Lead Halide Perovskite Nanocrystals and Bulk Crystals

    PubMed Central

    2016-01-01

    We report chemical routes for the synthesis of both nanocrystals and bulk crystals of methylammonium (MA) lead halide perovskites employing N-methylformamide (NMF) as a source of MA ions. Colloidal nanocrystals were prepared by a transamidation reaction between NMF and an alkyl amine (oleylamine). The nanocrystals showed photoluminescence quantum yields reaching 74% for MAPbBr3 and 60% for MAPbI3. Bulk crystals were grown at room temperature, with no need for an antisolvent, by the acid hydrolysis of NMF. Important advantages of using NMF instead of MA salts are that the syntheses involve fewer steps and less toxic and less expensive chemicals. PMID:28066824

  11. Computational study of the linear proton bound ion-molecule complexes of HCNH+ with HCN and HNC

    NASA Astrophysics Data System (ADS)

    Eric Cotton, C.; Francisco, Joseph S.; Klemperer, William

    2013-07-01

    This work reports the results of a high level ab initio study of the linear proton bound ion-molecule complex of HCNH+ with HCN and its isomer HNC. The energetics, equilibrium geometries, and predicted equilibrium rotational constants of three strongly interacting ion-molecule complexes are reported from calculations performed at the coupled-cluster calculations including singles, doubles, and perturbative triple excitations (CCSD(T))/aug-cc-pVnZ (n = 2-5) level of theory. Harmonic vibrational frequencies from calculations performed at the CCSD(T)/aug-cc-pVnZ (n = 2-4) level of theory are presented. Additional calculations are performed at the CCSD(T)-F12b/VnZ-F12 level of theory, and the associated energetics, equilibrium geometries, and equilibrium spectroscopic properties are reported. Anharmonicity is treated with the vibrational configuration interaction method, and the predicted anharmonic vibrational frequencies are reported. The results of these calculations show that of the four possible linear interactions of HCNH+ with HCN and HNC, there are three strongly interacting proton bound complexes. Further, the study presents results that the fourth possible interaction provides the basis for a novel HNC to HCN isomerization pathway in the interstellar medium.

  12. Development of high resolution linear-cut beam position monitor for heavy-ion synchrotron of KHIMA project

    NASA Astrophysics Data System (ADS)

    Hwang, Ji-Gwang; Yang, Tae-Keun; Forck, Peter; Noh, Seon Yeong; Hahn, Garam; Choi, Minkyoo

    2017-04-01

    A beam position monitor with high precision and resolution is required to control the beam trajectory for matching to the injection orbit and acceleration in a heavy-ion synchrotron. It will be also used for measuring the beta function, tune, and chromaticity. Since the bunch length at heavy ion synchrotron is relatively long, a few meters, a boxlike device with plates of typically 20 cm length is used to enhance the signal strength and to get a precise linear dependence with respect to the beam displacement. Especially, the linear-cut beam position monitor is adopted to satisfy the position resolution of 100 μm and accuracy of 200 μm for a nominal beam intensity in the KHIMA synchrotron of ∼ 7 ×108 particles for the carbon beams and ∼ 2 ×1010 for the proton beams. In this paper, we show the electromagnetic design of the electrode and surroundings to satisfy the resolution of 100 μm, the criteria for mechanical aspect to satisfy the position accuracy of 200 μm, the measurement results by using wire test-bench, design and measurement of a high input impedance pre-amplifier, and the beam-test results with long (∼1.6 μs) electron beam in Pohang accelerator laboratory (PAL).

  13. 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

  14. 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

  15. 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.

  16. Noninvasive Vibrational Mode Spectroscopy of Ion Coulomb Crystals through Resonant Collective Coupling to an Optical Cavity Field

    SciTech Connect

    Dantan, A.; Marler, J. P.; Albert, M.; Guenot, D.; Drewsen, M.

    2010-09-03

    We report on a novel noninvasive method to determine the normal mode frequencies of ion Coulomb crystals in traps based on the resonance enhanced collective coupling between the electronic states of the ions and an optical cavity field at the single photon level. Excitations of the normal modes are observed through a Doppler broadening of the resonance. An excellent agreement with the predictions of a zero-temperature uniformly charged liquid plasma model is found. The technique opens up for investigations of the heating and damping of cold plasma modes, as well as the coupling between them.

  17. Water channel formation and ion transport in linear and branched lipid bilayers.

    PubMed

    Wang, Shihu; Larson, Ronald G

    2014-04-28

    Using molecular dynamics simulations, we studied the influence of methyl chain branching on transmembrane potential induced formation of water channels in lipid bilayers and ion transport. We compared the response of a bilayer lipid that has multiple methyl branches diphytanoylphosphatidylcholine (DPhPC) with its straight-chain counterpart dipalmitoylphosphatidylcholine (DPPC) to a transmembrane potential created by an imbalance in ionic charges across the membrane. We found that, compared to the straight-chain DPPC lipid bilayer membranes, branched DPhPC lipid membranes require a higher critical transmembrane potential to break down, followed by water channel formation, and transport of anions and cations through the pore. We demonstrated that the bulkiness of the added methyl branches leads to "barrel-stave" pores in DPhPC membranes which require a higher transmembrane potential to produce than the toroidal pores produced in the straight chain DPPC lipid bilayers. Our results provided a deeper understanding of the water channel formation and ion transport through lipid bilayer membrane and might help explain the increased resistance to charge-induced poration in organisms with membranes abundant in branched lipids.

  18. Evidence of multicenter structure of cerium ions in gadolinium gallium garnet crystals studied by infrared absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Przybylińska, H.; Ma, Chong-Geng; Brik, M. G.; Kamińska, A.; Szczepkowski, J.; Sybilski, P.; Wittlin, A.; Berkowski, M.; Jastrzębski, W.; Suchocki, A.

    2013-01-01

    Low temperature, infrared absorption spectra of gadolinium gallium garnet crystals doped with Ce are presented. In the region of intraconfigurational 4f-4f transitions the spectra exhibit existence of at least two different, major Ce3+ related centers in the GGG crystals and also some other centers at lower concentration. The spectrum of 4f-4f intrashell transitions of Ce3+ ions extends up to about 3700 cm-1 due to the large splitting of the 2F7/2 excited state. In the visible region the absorption spectrum shows influence of symmetry-related selection rules. The absorption coefficient changes in the region of 4f1-5d1 transitions due to thermal population of the second level, belonging to the 2F5/2 ground state. This suggests that the symmetry of the site occupied by Ce3+ ions, which substitute Gd3+, is higher than D2 expected for garnet hosts.

  19. Upscaling Radionuclide Retardation?Linking the Surface Complexation and Ion Exchange Mechanistic Approach to a Linear Kd Approach

    SciTech Connect

    Zavarin, M; Carle, S; Maxwell, R

    2004-05-14

    The LLNL near-field hydrologic source term (HST) model is based on a mechanistic approach to radionuclide retardation-that is, a thermodynamic description of chemical processes governing retardation in the near field, such as aqueous speciation, surface complexation, ion exchange, and precipitation The mechanistic approach allows for radionuclide retardation to vary both in space and time as a function of the complex reaction chemistry of the medium. This level of complexity is necessary for near-field HST transport modeling because of the non-linear reaction chemistry expected close to the radiologic source. Large-scale Corrective Action Unit (CAU) models-into which the near-field HST model results feed-require that the complexity of the mechanistic approach be reduced to a more manageable form (e.g. Linear, Langmuir, or Freundlich sorption isotherms, etc). The linear sorption isotherm (or K{sub d}) approach is likely the most simple approach for large-scale CAU models. It may also be the most appropriate since the reaction chemistry away from the near field is expected to be less complex and relatively steady state. However, if the radionuclide retardation approaches in near-field HST and large-scale CAU models are different, they must be proved consistent. In this report, we develop a method to link the near-field HST and large-scale CAU model radionuclide retardation approaches.

  20. Attractive forces between ions in quantum plasmas: Failure of linearized quantum hydrodynamics

    NASA Astrophysics Data System (ADS)

    Bonitz, M.; Pehlke, E.; Schoof, T.

    2013-03-01

    In a recent Letter [P. K. Shukla and B. Eliasson, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.108.165007 108, 165007 (2012)] the discovery of a new attractive force between protons in a hydrogen plasma was reported that would be responsible for the formation of molecules and of a proton lattice. Here we show, based on ab initio density functional calculations and general considerations, that these predictions are not correct and caused by using linearized quantum hydrodynamics beyond the limits of its applicability.

  1. 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.

  2. Screening of Carotenoids in Tomato Fruits by Using Liquid Chromatography with Diode Array-Linear Ion Trap Mass Spectrometry Detection.

    PubMed

    Gentili, Alessandra; Caretti, Fulvia; Ventura, Salvatore; Pérez-Fernández, Virginia; Venditti, Alessandro; Curini, Roberta

    2015-08-26

    This paper presents an analytical strategy for a large-scale screening of carotenoids in tomato fruits by exploiting the potentialities of the triple quadrupole-linear ion trap hybrid mass spectrometer (QqQLIT). The method involves separation on C30 reversed-phase column and identification by means of diode array detection (DAD) and atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). The authentic standards of six model compounds were used to optimize the separative conditions and to predict the chromatographic behavior of untargeted carotenoids. An information dependent acquisition (IDA) was performed with (i) enhanced-mass scan (EMS) as the survey scan, (ii) enhanced-resolution (ER) scan to obtain the exact mass of the precursor ions (16-35 ppm), and (iii) enhanced product ion (EPI) scan as dependent scan to obtain structural information. LC-DAD-multiple reaction monitoring (MRM) chromatograms were also acquired for the identification of targeted carotenoids occurring at low concentrations; for the first time, the relative abundance between the MRM transitions (ion ratio) was used as an extra tool for the MS distinction of structural isomers and the related families of geometrical isomers. The whole analytical strategy was high-throughput, because a great number of experimental data could be acquired with few analytical steps, and cost-effective, because only few standards were used; when applied to characterize some tomato varieties ('Tangerine', 'Pachino', 'Datterino', and 'Camone') and passata of 'San Marzano' tomatoes, our method succeeded in identifying up to 44 carotenoids in the 'Tangerine'" variety.

  3. 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

  4. Ridge waveguide lasers in Nd:GGG crystals produced by swift carbon ion irradiation and femtosecond laser ablation.

    PubMed

    Jia, Yuechen; Dong, Ningning; Chen, Feng; Vázquez de Aldana, Javier R; Akhmadaliev, Sh; Zhou, Shengqiang

    2012-04-23

    We report on the fabrication of ridge waveguide in Nd:GGG crystal by using swift C(5+) ion irradiation and femtosecond laser ablation. At room temperature continuous wave laser oscillation at wavelength of ~1063 nm has been realized through the optical pump at 808 nm with a slope efficiency of 41.8% and the pump threshold is 71.6 mW.

  5. Strong tendency of homeotropic alignment and anisotropic lithium ion conductivity of sulfonate functionalized zwitterionic imidazolium ionic liquid crystals.

    PubMed

    Rondla, Rohini; Lin, Joseph C Y; Yang, C T; Lin, Ivan J B

    2013-09-17

    Here, we report the first attempt to investigate the liquid crystal (LC) behavior of SO3(-) functionalized imidazolium zwitterionic (SO3(-)ImZI) salts, which display homeotropic alignment on a glass slide without the aid of any aligning approach. Doping lithium salt to ImZI salts lowers the melting temperatures and raises the clearing temperatures substantially to form room temperature ImZILCs. Excellent anisotropic lithium ion conductivity is achieved; which is strengthened by their tendency for homeotropic alignment.

  6. Synthesis of Large-Sized Single-Crystal Hexagonal Boron Nitride Domains on Nickel Foils by Ion Beam Sputtering Deposition.

    PubMed

    Wang, Haolin; Zhang, Xingwang; Liu, Heng; Yin, Zhigang; Meng, Junhua; Xia, Jing; Meng, Xiang-Min; Wu, Jinliang; You, Jingbi

    2015-12-22

    Large-sized single-crystal h-BN domains with a lateral size up to 100 μm are synthesized on Ni foils by ion-beam sputtering deposition. The nucleation density of h-BN is dramatically decreased by reducing the concentrations of both active sites and species on the Ni surface through a brief in situ pretreatment of the substrate and optimization of the growth parameters, enabling the growth of large-sized domains.

  7. Superstructures in cubic A{sup II}B{sup VI} crystals heavily doped with Ni and V ions

    SciTech Connect

    Maksimov, V. I. Dubinin, S. F.; Surkova, T. P.

    2016-01-15

    Specific features of the crystal structure of bulk sphalerite-type Zn{sub 0.9}Ni{sub 0.1}S, Zn{sub 0.9}V{sub 0.1}Se, and Zn{sub 0.997}Ni{sub 0.003}Te crystals have been investigated in detail by thermal-neutron diffraction at room temperature. Fine effects (indicative of the existence of distortion microdomains, nucleation of long- and short-wavelength modulations, and tendencies toward local lowering of the symmetry based on the initial cubic structure) can be observed in the obtained scattering patterns. Various states preceding the fcc ↔ hcp phase transition have been revealed in these crystals. They depend on the elemental composition and are formed upon the reaction of the initial lattice to perturbations induced by foreign ions with an incomplete 3d shell.

  8. Can zinc(II) ions be doped into the crystal structure of L-proline cadmium chloride monohydrate?

    PubMed

    Srinivasan, Bikshandarkoil R

    2013-12-01

    The bivalent metals Cd(II) and Zn(II) exhibit different stereochemical requirements for the set of chloride and L-proline ligands, which precludes the doping of Zn(II) ions into the crystal structure of dichloro(l-proline)cadmium(II) hydrate also referred to as L-proline cadmium chloride monohydrate (L-PCCM). Hence, the reported claim of growth of zinc doped L-PCCM crystals namely Zn(0.4 mol):LPCCM and Zn(0.2 mol):LPCCM by Vetrivel et al. (S. Vetrivel, P. Anandan, K. Kanagasabapathy, S. Bhattacharya, S. Gopinath, R. Rajasekaran, Effect of zinc chloride on the growth and characterization of l-proline cadmium chloride monohydrate semiorganic NLO single crystals, Spectrochim. Acta 110A (2013) 317-323), is untenable.

  9. Crystallization of calcium sulfate dihydrate under simulated conditions of phosphoric acid production in the presence of aluminum and magnesium ions

    NASA Astrophysics Data System (ADS)

    Rashad, M. M.; Mahmoud, M. H. H.; Ibrahim, I. A.; Abdel-Aal, E. A.

    2004-06-01

    The effect of Al 3+ and Mg 2+ ions, as additives, on the crystallization of gypsum was studied under simulated conditions of the phosphoric acid production. Calcium hydrogen phosphate and sulfuric acid were mixed with dilute phosphoric acid at 80°C, and the turbidity of the reaction mixture was measured at different time periods to calculate the induction time of gypsum crystals formation. Addition of Al 3+ ions up to 2% decreased the induction time and increased the growth efficiency while addition of Mg 2+ increased the induction time and decreased the growth efficiency compared with in absence of additives. Interestingly, the crystals mean and median diameters were found to increase in the presence of Al 3+ and decrease in the presence of Mg 2+. The surface energy increased with Al 3+ and decreased with Mg 2+ compared to the baseline (without additives). Gypsum morphology changed from needle-like type in absence of additives to thick-rhombic in the presence of Al 3+ ions.

  10. Spatially Resolved Spectra from a new X-ray Imaging Crystal Spectrometer for Measurements of Ion and Electron Temperature Profiles

    SciTech Connect

    Bitter, M; Stratton, B; Roquemore, A; Mastrovito, D; Lee, S; Bak, J; Moon, M; Nam, U; Smith, G; Rice, J; Beiersdorfer, P; Fraenkel, B

    2004-08-10

    A new type of high-resolution X-ray imaging crystal spectrometer is being developed to measure ion and electron temperature profiles in tokamak plasmas. The instrument is particularly valuable for diagnosing plasmas with purely Ohmic heating and rf heating, since it does not require the injection of a neutral beam - although it can also be used for the diagnosis of neutral-beam heated plasmas. The spectrometer consists of a spherically bent quartz crystal and a two-dimensional position-sensitive detector. It records spectra of helium-like argon (or krypton) from multiple sightlines through the plasma and projects a de-magnified image of a large plasma cross-section onto the detector. The spatial resolution in the plasma is solely determined by the height of the crystal, its radius of curvature, and the Bragg angle. This new X-ray imaging crystal spectrometer may also be of interest for the diagnosis of ion temperature profiles in future large tokamaks, such as KSTAR and ITER, where the application of the presently used charge-exchange spectroscopy will be difficult, if the neutral beams do not penetrate to the plasma center. The paper presents the results from proof-of-principle experiments performed with a prototype instrument at Alcator C-Mod.

  11. Co-crystal and crystal: Supramolecular arrangement obtained from 4-aminosalicylic acid, bpa ligand and cobalt ion

    NASA Astrophysics Data System (ADS)

    Garcia, Humberto C.; Cunha, Ronaldo T.; Diniz, Renata; de Oliveira, Luiz Fernando C.

    2012-02-01

    In this study, the synthesis, spectroscopic properties (infrared and Raman) and crystal structures of two new compounds co-crystal and crystal named HASbpa (1) and [Co(bpa)(H2O)4]AS2ṡ4H2O (2) have been reported, where bpa is trans-1,2-bis(4-pyridyl)ethane, HAS is 4-aminosalicylic acid and AS- is aminosalicylate anion. The crystalline arrangement of the compound 1 exhibits a triclinic system with space group P1¯. The formation of a structure known as co-crystal, composed by building blocks in their neutral form; being the first work of this type involving the HAS and nitrogen ligand as bpa. For compound 2, a monoclinic system was observed with P21/c space group. The crystalline arrangement of the structure consisted of a covalent one-dimensional cationic [Co(bpa)(H2O)4]2+ chain, which interacts by hydrogen bonding, π-stacking and electrostatic interactions with aminosalicylate anions and water molecules that were trapped in the crystal. These interactions form supramolecular cavities denominated as pseudo honeycombs. For compound 1, the infrared spectrum revealed the presence of bands at 1643 and 1601 cm-1 assigned to the stretching mode of CO [ν(CO)] and CC/CN groups [ν(CC/CN)]. For the Raman spectrum, these same modes appear around 1644 and 1602 cm-1 related to HAS and bpa blocks, respectively. For compound 2, the largest displacement of the bands compared to free ligand suggested the formation of covalent bonds between bpa ligand and metallic site and loss of the proton in HAS molecule. In the infrared spectrum we can observe the presence of bands around 1635 and 1618 cm-1 attributed to the stretching ν(COO-) and ν(CC/CN), for the Raman spectrum these same modes appear around 1631 and 1619 cm-1 related to AS- and bpa ligand respectively.

  12. Electron-ion hybrid instability experiment upgrades to the Auburn Linear Experiment for Instability Studies

    SciTech Connect

    DuBois, A. M.; Arnold, I.; Thomas, E. Jr.; Tejero, E.; Amatucci, W. E.

    2013-04-15

    The Auburn Linear EXperiment for Instability Studies (ALEXIS) is a laboratory plasma physics experiment used to study spatially inhomogeneous flows in a magnetized cylindrical plasma column that are driven by crossed electric (E) and magnetic (B) fields. ALEXIS was recently upgraded to include a small, secondary plasma source for a new dual source, interpenetrating plasma experiment. Using two plasma sources allows for highly localized electric fields to be made at the boundary of the two plasmas, inducing strong E Multiplication-Sign B velocity shear in the plasma, which can give rise to a regime of instabilities that have not previously been studied in ALEXIS. The dual plasma configuration makes it possible to have independent control over the velocity shear and the density gradient. This paper discusses the recent addition of the secondary plasma source to ALEXIS, as well as the plasma diagnostics used to measure electric fields and electron densities.

  13. Crystal structure of the ATP-gated P2X[subscript 4] ion channel in the closed state

    SciTech Connect

    Kawate, Toshimitsu; Michel, Jennifer Carlisle; Birdsong, William T.; Gouaux, Eric

    2009-08-13

    P2X receptors are cation-selective ion channels gated by extracellular ATP, and are implicated in diverse physiological processes, from synaptic transmission to inflammation to the sensing of taste and pain. Because P2X receptors are not related to other ion channel proteins of known structure, there is at present no molecular foundation for mechanisms of ligand-gating, allosteric modulation and ion permeation. Here we present crystal structures of the zebrafish P2X{sub 4} receptor in its closed, resting state. The chalice-shaped, trimeric receptor is knit together by subunit-subunit contacts implicated in ion channel gating and receptor assembly. Extracellular domains, rich in {beta}-strands, have large acidic patches that may attract cations, through fenestrations, to vestibules near the ion channel. In the transmembrane pore, the 'gate' is defined by an {approx}8 {angstrom} slab of protein. We define the location of three non-canonical, intersubunit ATP-binding sites, and suggest that ATP binding promotes subunit rearrangement and ion channel opening.

  14. Molecular dynamics of glycine ions in alanine doped TGS single crystal as probed by polarized laser raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Bajpai, P. K.; Verma, A. L.

    2012-10-01

    Polarized Raman spectra of pure and alanine doped tri-glycine sulfate (TGS) single crystals at 12 K in different scattering geometries are analyzed. Sub species modes due to three crystallographically distinguishable glycine ions G (I), G (II) and G (III) are assigned. It is observed that alanine doping does not change the crystalline field and acts as local perturbation only. The major changes due to doping are observed in the relative intensities of different modes; most of the modes associated with G (I) and SO42- ions show reversal behavior in relative intensity at high doping concentration. The observed spectral changes are analyzed in terms of reorientation of G (I) ions with sub species modes of G (II)/ G (III) following the reorientation due to complex hydrogen bonding network.

  15. Molecular dynamics of glycine ions in alanine doped TGS single crystal as probed by polarized laser Raman spectroscopy.

    PubMed

    Bajpai, P K; Verma, A L

    2012-10-01

    Polarized Raman spectra of pure and alanine doped tri-glycine sulfate (TGS) single crystals at 12 K in different scattering geometries are analyzed. Sub species modes due to three crystallographically distinguishable glycine ions G (I), G (II) and G (III) are assigned. It is observed that alanine doping does not change the crystalline field and acts as local perturbation only. The major changes due to doping are observed in the relative intensities of different modes; most of the modes associated with G (I) and SO(4)(2-) ions show reversal behavior in relative intensity at high doping concentration. The observed spectral changes are analyzed in terms of reorientation of G (I) ions with sub species modes of G (II)/ G (III) following the reorientation due to complex hydrogen bonding network.

  16. Lattice damage assessment and optical waveguide properties in LaAlO3 single crystal irradiated with swift Si ions

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Crespillo, M. L.; Huang, Q.; Wang, T. J.; Liu, P.; Wang, X. L.

    2017-02-01

    As one of the representative ABO3 perovskite-structured oxides, lanthanum aluminate (LaAlO3) crystal has emerged as one of the most valuable functional-materials, and has attracted plenty of fundamental research and promising applications in recent years. Electronic, magnetic, optical and other properties of LaAlO3 strongly depend on its crystal structure, which could be strongly modified owing to the nuclear or electronic energy loss deposited in an ion irradiation environment and, therefore, significantly affecting the performance of LaAlO3-based devices. In this work, utilizing swift (tens of MeV) Si-ion irradiation, the damage behavior of LaAlO3 crystal induced by nuclear or electronic energy loss has been studied in detail utilizing complementary characterization techniques. Differing from other perovskite-structured crystals in which the electronic energy loss could lead to the formation of an amorphous region based on the thermal spike mechanism, in this case, intense electronic energy loss in LaAlO3 will not induce any obvious structural damage. The effects of ion irradiation on the mechanical properties, including hardness increase and elastic modulus decrease, have been confirmed. On the other hand, considering the potential applications of LaAlO3 in the field of integrated optoelectronics, the optical-waveguide properties of the irradiation region have been studied. The significant correspondence (symmetrical inversion) between the iWKB-reconstructed refractive-index profile and SRIM-simulated dpa profile further proves the effects (irradiation-damage production and refractive-index decrease) of nuclear energy loss during the swift-ion penetration process in LaAlO3 crystal. In the case of the rather-thick damage layer produced by swift-ion irradiation, obtaining a damage profile will be constrained owing to the analysis-depth limitation of the characterization techniques (RBS/channeling), and our analysis process (optical guided-mode measurement and

  17. An ion microprobe study of the intra-crystalline behavior of REE and selected trace elements in pyroxene from mare basalts with different cooling and crystallization histories

    NASA Technical Reports Server (NTRS)

    Shearer, C. K.; Papike, J. J.; Simon, S. B.; Shimizu, N.

    1989-01-01

    The effects of crystallization interaction on the trace element zoning characteristics of pyroxenes are analyzed using electron and ion microprobe techniques. Four pigeonite basalts with similar isochemical composition, but different cooling rates and crystallization histories are studied. Pyroxene quadrilaterals displaying crystallization trends are presented. The crystal chemical rationalization of REE zoning, pattern shapes, and abundances are examined. The data reveal that the trace element zoning characteristics in pyroxene and the partitioning of trace elements between pyroxene and the melt are related to the interaction between the efficiency of the crystallization process, the kinetics at the crystal-melt interface, the kinetics of plagioclase nucleation and the characteristics of the crystal chemical substitutions in the pyroxene and the associated crystallizing phase.

  18. Upgrade of the MIT Linear Electrostatic Ion Accelerator (LEIA) for nuclear diagnostics development for Omega, Z and the NIF.

    PubMed

    Sinenian, N; Manuel, M J-E; Zylstra, A B; Rosenberg, M; Waugh, C J; Rinderknecht, H G; Casey, D T; Sio, H; Ruszczynski, J K; Zhou, L; Gatu Johnson, M; Frenje, J A; Séguin, F H; Li, C K; Petrasso, R D; Ruiz, C L; Leeper, R J

    2012-04-01

    The MIT Linear Electrostatic Ion Accelerator (LEIA) generates DD and D(3)He fusion products for the development of nuclear diagnostics for Omega, Z, and the National Ignition Facility (NIF). Significant improvements to the system in recent years are presented. Fusion reaction rates, as high as 10(7) s(-1) and 10(6) s(-1) for DD and D(3)He, respectively, are now well regulated with a new ion source and electronic gas control system. Charged fusion products are more accurately characterized, which allows for better calibration of existing nuclear diagnostics. In addition, in situ measurements of the on-target beam profile, made with a CCD camera, are used to determine the metrology of the fusion-product source for particle-counting applications. Finally, neutron diagnostics development has been facilitated by detailed Monte Carlo N-Particle Transport (MCNP) modeling of neutrons in the accelerator target chamber, which is used to correct for scattering within the system. These recent improvements have resulted in a versatile platform, which continues to support the existing nuclear diagnostics while simultaneously facilitating the development of new diagnostics in aid of the National Ignition Campaign at the National Ignition Facility.

  19. The interplay of the collisionless non-linear thin-shell instability with the ion acoustic instability

    NASA Astrophysics Data System (ADS)

    Dieckmann, M. E.; Folini, D.; Walder, R.

    2017-03-01

    The non-linear thin-shell instability (NTSI) may explain some of the turbulent hydrodynamic structures that are observed close to the collision boundary of energetic astrophysical outflows. It develops in non-planar shells that are bounded on either side by a hydrodynamic shock, provided that the amplitude of the seed oscillations is sufficiently large. The hydrodynamic NTSI has a microscopic counterpart in collisionless plasma. A sinusoidal displacement of a thin shell, which is formed by the collision of two clouds of unmagnetized electrons and protons, grows and saturates on time-scales of the order of the inverse proton plasma frequency. Here we increase the wavelength of the seed perturbation by a factor of 4 compared to that in a previous study. Like in the case of the hydrodynamic NTSI, the increase in the wavelength reduces the growth rate of the microscopic NTSI. The prolonged growth time of the microscopic NTSI allows the waves, which are driven by the competing ion acoustic instability, to grow to a large amplitude before the NTSI saturates and they disrupt the latter. The ion acoustic instability thus imposes a limit on the largest wavelength that can be destabilized by the NTSI in collisionless plasma. The limit can be overcome by binary collisions. We bring forward evidence for an overstability of the collisionless NTSI.

  20. Comment on ``Attractive forces between ions in quantum plasmas: Failure of linearized quantum hydrodynamics''

    NASA Astrophysics Data System (ADS)

    Shukla, P. K.; Eliasson, B.; Akbari-Moghanjoughi, M.

    2013-03-01

    In a recent paper, Bonitz, Pehlke, and Schoof [Phys. Rev. E10.1103/PhysRevE.87.033105 87, 033105 (2013)], hereafter referred to as BPS, have raised some points against the Shukla-Eliasson attractive potential [P. K. Shukla and B. Eliasson, Phys. Rev. Lett.0031-900710.1103/PhysRevLett.108.165007 108, 165007 (2012); P. K. Shukla and B. Eliasson, Phys. Rev. Lett.0031-900710.1103/PhysRevLett.108.219902 108, 219902(E) (2012); P. K. Shukla and B. Eliasson, Phys. Rev. Lett.10.1103/PhysRevLett.109.019901 109, 019901(E) (2012)], hereafter referred to as SEAP, around a stationary test charge in a quantum plasma. Our objective here is to discuss the insufficiency of the BPS reasoning concerning the applicability of the linearized quantum hydrodynamic theory, as well as to point out the shortcomings in BPS’s arguments and to suggest how to salvage BPS’s density functional theory and simulations, which have failed to produce results that correctly match with that of Shukla and Eliasson.

  1. Plasma polymerization and deposition of linear, cyclic and aromatic fluorocarbons on (100)-oriented single crystal silicon substrates

    NASA Astrophysics Data System (ADS)

    Yang, G. H.; Oh, S. W.; Kang, E. T.; Neoh, K. G.

    2002-11-01

    Fluoropolymer films were deposited on the Ar plasma-pretreated Si(100) surfaces by plasma polymerization of perfluorohexane (PFH, a linear fluorocarbon), perfluoro(methylcyclohexane) (MCH, a cyclic fluorocarbon), and hexafluorobenzene (HFB, an aromatic fluorocarbon) under different glow discharge conditions. The effects of the radio-frequency plasma power on the chemical composition and structure of the plasma-polymerized fluoropolymer films were studied by x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, time-of-flight secondary ion mass spectrometry, and water contact angle measurements. The changes in structure and composition of the three types of the plasma-deposited films from those of the respective fluorocarbons were compared. Under similar glow discharge conditions: (i) the extent of defluorination was highest for the PFH polymer, (ii) the deposition rate was highest for the HFB polymer, (iii) the cyclic structure of MCH was less well preserved than the aromatic structure of HFB, (iv) aliphatic structures appeared in the plasma-deposited MCH polymer, and (v) the plasma-polymerized HFB has the highest thermal stability due to the preservation of the aromatic rings. The adhesive tape peel test results revealed that the plasma-polymerized and deposited fluoropolymer layers were strongly bonded to the Ar plasma-pretreated Si(100) surfaces.

  2. Estimation of absorbed dose in clinical radiotherapy linear accelerator beams: Effect of ion chamber calibration and long-term stability.

    PubMed

    Ravichandran, Ramamoorthy; Binukumar, Johnson Pichy; Davis, Cheriyathmanjiyil Antony

    2013-10-01

    The measured dose in water at reference point in phantom is a primary parameter for planning the treatment monitor units (MU); both in conventional and intensity modulated/image guided treatments. Traceability of dose accuracy therefore still depends mainly on the calibration factor of the ion chamber/dosimeter provided by the accredited Secondary Standard Dosimetry Laboratories (SSDLs), under International Atomic Energy Agency (IAEA) network of laboratories. The data related to Nd,water calibrations, thermoluminescent dosimetry (TLD) postal dose validation, inter-comparison of different dosimeter/electrometers, and validity of Nd,water calibrations obtained from different calibration laboratories were analyzed to find out the extent of accuracy achievable. Nd,w factors in Gray/Coulomb calibrated at IBA, GmBH, Germany showed a mean variation of about 0.2% increase per year in three Farmer chambers, in three subsequent calibrations. Another ion chamber calibrated in different accredited laboratory (PTW, Germany) showed consistent Nd,w for 9 years period. The Strontium-90 beta check source response indicated long-term stability of the ion chambers within 1% for three chambers. Results of IAEA postal TL "dose intercomparison" for three photon beams, 6 MV (two) and 15 MV (one), agreed well within our reported doses, with mean deviation of 0.03% (SD 0.87%) (n = 9). All the chamber/electrometer calibrated by a single SSDL realized absorbed doses in water within 0.13% standard deviations. However, about 1-2% differences in absorbed dose estimates observed when dosimeters calibrated from different calibration laboratories are compared in solid phantoms. Our data therefore imply that the dosimetry level maintained for clinical use of linear accelerator photon beams are within recommended levels of accuracy, and uncertainties are within reported values.

  3. Comprehensive Lipidome Analysis by Shotgun Lipidomics on a Hybrid Quadrupole-Orbitrap-Linear Ion Trap Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Almeida, Reinaldo; Pauling, Josch Konstantin; Sokol, Elena; Hannibal-Bach, Hans Kristian; Ejsing, Christer S.

    2015-01-01

    Here we report on the application of a novel shotgun lipidomics platform featuring an Orbitrap Fusion mass spectrometer equipped with an automated nanoelectrospray ion source. To assess the performance of the platform for in-depth lipidome analysis, we evaluated various instrument parameters, including its high resolution power unsurpassed by any other contemporary Orbitrap instrumentation, its dynamic quantification range and its efficacy for in-depth structural characterization of molecular lipid species by quadrupole-based higher-energy collisional dissociation (HCD), and ion trap-based resonant-excitation collision-induced dissociation (CID). This evaluation demonstrated that FTMS analysis with a resolution setting of 450,000 allows distinguishing isotopes from different lipid species and features a linear dynamic quantification range of at least four orders of magnitude. Evaluation of fragmentation analysis demonstrated that combined use of HCD and CID yields complementary fragment ions of molecular lipid species. To support global lipidome analysis, we designed a method, termed MSALL, featuring high resolution FTMS analysis for lipid quantification, and FTMS2 analysis using both HCD and CID and ITMS3 analysis utilizing dual CID for in-depth structural characterization of molecular glycerophospholipid species. The performance of the MSALL method was benchmarked in a comparative analysis of mouse cerebellum and hippocampus. This analysis demonstrated extensive lipidome quantification covering 311 lipid species encompassing 20 lipid classes, and identification of 202 distinct molecular glycerophospholipid species when applying a novel high confidence filtering strategy. The work presented here validates the performance of the Orbitrap Fusion mass spectrometer for in-depth lipidome analysis.

  4. Comprehensive lipidome analysis by shotgun lipidomics on a hybrid quadrupole-orbitrap-linear ion trap mass spectrometer.

    PubMed

    Almeida, Reinaldo; Pauling, Josch Konstantin; Sokol, Elena; Hannibal-Bach, Hans Kristian; Ejsing, Christer S

    2015-01-01

    Here we report on the application of a novel shotgun lipidomics platform featuring an Orbitrap Fusion mass spectrometer equipped with an automated nanoelectrospray ion source. To assess the performance of the platform for in-depth lipidome analysis, we evaluated various instrument parameters, including its high resolution power unsurpassed by any other contemporary Orbitrap instrumentation, its dynamic quantification range and its efficacy for in-depth structural characterization of molecular lipid species by quadrupole-based higher-energy collisional dissociation (HCD), and ion trap-based resonant-excitation collision-induced dissociation (CID). This evaluation demonstrated that FTMS analysis with a resolution setting of 450,000 allows distinguishing isotopes from different lipid species and features a linear dynamic quantification range of at least four orders of magnitude. Evaluation of fragmentation analysis demonstrated that combined use of HCD and CID yields complementary fragment ions of molecular lipid species. To support global lipidome analysis, we designed a method, termed MS(ALL), featuring high resolution FTMS analysis for lipid quantification, and FTMS(2) analysis using both HCD and CID and ITMS(3) analysis utilizing dual CID for in-depth structural characterization of molecular glycerophospholipid species. The performance of the MS(ALL) method was benchmarked in a comparative analysis of mouse cerebellum and hippocampus. This analysis demonstrated extensive lipidome quantification covering 311 lipid species encompassing 20 lipid classes, and identification of 202 distinct molecular glycerophospholipid species when applying a novel high confidence filtering strategy. The work presented here validates the performance of the Orbitrap Fusion mass spectrometer for in-depth lipidome analysis.

  5. Continuous piecewise-linear, reduced-order electrochemical model for lithium-ion batteries in real-time applications

    NASA Astrophysics Data System (ADS)

    Farag, Mohammed; Fleckenstein, Matthias; Habibi, Saeid

    2017-02-01

    Model-order reduction and minimization of the CPU run-time while maintaining the model accuracy are critical requirements for real-time implementation of lithium-ion electrochemical battery models. In this paper, an isothermal, continuous, piecewise-linear, electrode-average model is developed by using an optimal knot placement technique. The proposed model reduces the univariate nonlinear function of the electrode's open circuit potential dependence on the state of charge to continuous piecewise regions. The parameterization experiments were chosen to provide a trade-off between extensive experimental characterization techniques and purely identifying all parameters using optimization techniques. The model is then parameterized in each continuous, piecewise-linear, region. Applying the proposed technique cuts down the CPU run-time by around 20%, compared to the reduced-order, electrode-average model. Finally, the model validation against real-time driving profiles (FTP-72, WLTP) demonstrates the ability of the model to predict the cell voltage accurately with less than 2% error.

  6. The application of the McLachlan approximation to π-electron open-shell crystal orbital calculations on columnar stacks of macrocyclic radical ions

    NASA Astrophysics Data System (ADS)

    Honeybourne, Colin L.

    The criterion of Katz et al., for the minimum required velocity for charge carriers in a band has been used to identify those columnar stacks of radical ions to which the band model is applicable in the context of extrinsic semiconduction. The open-shell π-electron crystal orbital methods used are those of Ladik and of Honeybourne, the latter method being presented herein. On the basis of the width of the band housing the odd α-electron (and the consequent charge carrier velocity) the band model is applicable to the majority of radical cations studied and to the radical anions of compounds [5, 14]-dihydrodibenzo [b, i] [1, 4, 5, 8, 9, 11, 12, 14] octaaza cyclotetradecine and tetrabenzo [b, f, j, n] [1, 5, 9, 13] tetraaza cyclohexadecine at an interplanar separation of 0·373 nm. At a separation of 0·336 nm, the band model is applicable to all twenty two pseudo-linear, perfectly columnar stacks of macrocyclic radical ions.

  7. Thermal, mechanical, electrical, linear and nonlinear optical properties of a nonlinear optical L-ornithine monohydrochloride single crystal

    NASA Astrophysics Data System (ADS)

    Senthil, S.; Pari, S.; Joseph, Ginson P.; Sagayaraj, P.; Madhavan, J.

    2009-08-01

    Optically transparent semiorganic nonlinear optical bulk single crystal of L-ornithine monohydrochloride (LOMHCL) of dimension 11×3×2 mm 3 has been grown from its aqueous solution by slow solvent evaporation technique. The grown crystal was characterized by powder X-ray diffraction to confirm the crystal structure. Investigation has been carried out to assign the vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopy technique. Thermal behavior of the grown crystals was studied by thermogravimetric analysis. The second harmonic generation (SHG) efficiency of LOMHCL was determined by Kurtz and Perry powder technique. The optical absorption study confirms the suitability of the crystal for device applications. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. Dielectric and photoconductivity studies are also carried out for the grown samples.

  8. Carbon Ion Irradiation of the Rat Spinal Cord: Dependence of the Relative Biological Effectiveness on Linear Energy Transfer

    SciTech Connect

    Saager, Maria; Glowa, Christin; Peschke, Peter; Brons, Stephan; Scholz, Michael; Huber, Peter E.; Debus, Jürgen; Karger, Christian P.

    2014-09-01

    Purpose: To measure the relative biological effectiveness (RBE) of carbon ions in the rat spinal cord as a function of linear energy transfer (LET). Methods and Materials: As an extension of a previous study, the cervical spinal cord of rats was irradiated with single doses of carbon ions at 6 positions of a 6-cm spread-out Bragg peak (16-99 keV/μm). The TD{sub 50} values (dose at 50% complication probability) were determined according to dose-response curves for the development of paresis grade 2 within an observation time of 300 days. The RBEs were calculated using TD{sub 50} for photons of our previous study. Results: Minimum latency time was found to be dose-dependent, but not significantly LET-dependent. The TD{sub 50} values for the onset of paresis grade 2 within 300 days were 19.5 ± 0.4 Gy (16 keV/μm), 18.4 ± 0.4 Gy (21 keV/μm), 17.7 ± 0.3 Gy (36 keV/μm), 16.1 ± 1.2 Gy (45 keV/μm), 14.6 ± 0.5 Gy (66 keV/μm), and 14.8 ± 0.5 Gy (99 keV/μm). The corresponding RBEs increased from 1.26 ± 0.05 (16 keV/μm) up to 1.68 ± 0.08 at 66 keV/μm. Unexpectedly, the RBE at 99 keV/μm was comparable to that at 66 keV/μm. Conclusions: The data suggest a linear relation between RBE and LET at high doses for late effects in the spinal cord. Together with additional data from ongoing fractionated irradiation experiments, these data will provide an extended database to systematically benchmark RBE models for further improvements of carbon ion treatment planning.

  9. Mineralomimetic sodalite- and muscovite-type coordination frameworks. Dynamic crystal-to-crystal interconversion processes sensitive to ion pair recognition.

    PubMed

    Barea, Elisa; Navarro, Jorge A R; Salas, Juan M; Masciocchi, Norberto; Galli, Simona; Sironi, Angelo

    2004-03-17

    A flexible sodalite-type metal organic framework [Cu(pyrimidine-2-olate)2]n (1R) is obtained in a self-assembly process involving Cu2+ ions and pyrimidine-2-olate ligands. 1R suffers a series of sequential and reversible structural changes upon solid-liquid sorption processes of metal nitrates. The 1C-to-1O transformation occurs only with large cations.

  10. Curvature oscillations and linear electro-optical effect in a surface layer of a nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Blinov, L. M.; Durand, G.; Yablonsky, S. V.

    1992-05-01

    Damped curvature oscillations are excited at the surface between a nematic liquid crystal and a solid substrate, from the linear coupling of an AC electric field with the flexoelectric properties of the medium. The waves are detected by a modulation ellipsometry technique. Linear-in-field oscillations of the director in the surface nematic layer have been observed. The amplitude and characteristic response time of the oscillations are defined by visco-elastic and flexoelectric properties of the medium and the overlaping of the curvature wave with the profile of the sampling optical evanescent wave. A simple model is discussed which is in good agreement with experiments performed on a compensated MBBA mixture (with zero dielectric anisotropy) and 5CB. The anchoring energy for the nematic in contact with obliquely evaported SiO layer, as well as the sum e_1 +e_3 of the flexoelectric coefficients are measured, indicating a surface order parameter smaller than its bulk value. Des oscillations de courbure amorties sont excitées à l'interface entre un cristal liquide nématique et un substrat solide, par le couplage linéaire entre un champ électrique alternatif et la polarisation flexoélectrique du nématique. Les ondes sont détectées par une technique ellipsométrique. On observe une oscillation du directeur à la fréquence du champ. L'anplitude et le temps caractéristique de cette oscillation sont définis par les propriétés viscoélastiques et flexoélectriques du milieu, et le recouvrement de l'onde de courbure avec le profil de l'onde optique évanescente de mesure. Un modèle simple est discuté, en bon accord avec les expériences, faites sur un mélange compensé de MBBA (d'anisotropie diélectrique nulle) et sur du 5CB. L'énergie d'ancrage sur l'électrode évaporée SiO oblique, et la somme e_1 +e_3 des coefficients flexoélectriques sont mesurées, indiquant une baisse du paramètre d'ordre en surface.

  11. 5 d-4 f luminescence of Nd3+, Gd3+, Er3+, Tm3+, and Ho3+ ions in crystals of alkaline earth fluorides

    NASA Astrophysics Data System (ADS)

    Radzhabov, E. A.; Prosekina, E. A.

    2011-09-01

    The vacuum ultraviolet emission spectra of alkaline-earth fluoride (CaF2, SrF2, BaF2) crystals with rare earth impurity ions (Nd, Gd, Er, Tm, Ho) have been investigated. The main luminescence bands are described well by the transitions from the lowest excited 5 d state to different 4 f levels of rare earth ions.

  12. Imaging MS Methodology for More Chemical Information in Less Data Acquisition Time Utilizing a Hybrid Linear Ion Trap-Orbitrap Mass Spectrometer

    SciTech Connect

    Perdian, D. C.; Lee, Young Jin

    2010-11-15

    A novel mass spectrometric imaging method is developed to reduce the data acquisition time and provide rich chemical information using a hybrid linear ion trap-orbitrap mass spectrometer. In this method, the linear ion trap and orbitrap are used in tandem to reduce the acquisition time by incorporating multiple linear ion trap scans during an orbitrap scan utilizing a spiral raster step plate movement. The data acquisition time was decreased by 43-49% in the current experiment compared to that of orbitrap-only scans; however, 75% or more time could be saved for higher mass resolution and with a higher repetition rate laser. Using this approach, a high spatial resolution of 10 {micro}m was maintained at ion trap imaging, while orbitrap spectra were acquired at a lower spatial resolution, 20-40 {micro}m, all with far less data acquisition time. Furthermore, various MS imaging methods were developed by interspersing MS/MS and MSn ion trap scans during orbitrap scans to provide more analytical information on the sample. This method was applied to differentiate and localize structural isomers of several flavonol glycosides from an Arabidopsis flower petal in which MS/MS, MSn, ion trap, and orbitrap images were all acquired in a single data acquisition.

  13. Growth and characterization of non-linear optical crystal Cd{sub 3}Zn{sub 3}B{sub 4}O{sub 12}

    SciTech Connect

    Zhang Fan Shen Dezhong Shen Guangqiu; Wang Xiaoqing

    2008-12-01

    Cd{sub 3}Zn{sub 3}B{sub 4}O{sub 12} polycrystals were synthesized by solid-state and wet chemical reaction methods. Cd{sub 3}Zn{sub 3}B{sub 4}O{sub 12} single crystals with millimeter grade were grown from the self-flux B{sub 2}O{sub 3} (Cd:Zn:B = 1:1:1.5); and larger crystals were obtained from the PbO-0.85PbF{sub 2} fluxes easily. As-grown crystals were characterized by differential scanning calorimetry and thermogravimetric, X-ray diffraction, infrared and Raman spectral analysis, respectively. The non-linear optical coefficient of the Cd{sub 3}Zn{sub 3}B{sub 4}O{sub 12} crystal is 2.6 times as large as that of KH{sub 2}PO{sub 4} crystal. Chemical etching shows that this crystal is very stable in neutral solution and not hygroscopic in air at room temperature.

  14. Structural basis for ion selectivity revealed by high-resolution crystal structure of Mg2+ channel MgtE.

    PubMed

    Takeda, Hironori; Hattori, Motoyuki; Nishizawa, Tomohiro; Yamashita, Keitaro; Shah, Syed T A; Caffrey, Martin; Maturana, Andrés D; Ishitani, Ryuichiro; Nureki, Osamu

    2014-11-04

    Magnesium is the most abundant divalent cation in living cells and is crucial to several biological processes. MgtE is a Mg(2+) channel distributed in all domains of life that contributes to the maintenance of cellular Mg(2+) homeostasis. Here we report the high-resolution crystal structures of the transmembrane domain of MgtE, bound to Mg(2+), Mn(2+) and Ca(2+). The high-resolution Mg(2+)-bound crystal structure clearly visualized the hydrated Mg(2+) ion within its selectivity filter. Based on those structures and biochemical analyses, we propose a cation selectivity mechanism for MgtE in which the geometry of the hydration shell of the fully hydrated Mg(2+) ion is recognized by the side-chain carboxylate groups in the selectivity filter. This is in contrast to the K(+)-selective filter of KcsA, which recognizes a dehydrated K(+) ion. Our results further revealed a cation-binding site on the periplasmic side, which regulate channel opening and prevents conduction of near-cognate cations.

  15. Selective laser spectroscopy of SrF{sub 2} crystal doped with Pr{sup 3+} ions

    SciTech Connect

    Alimov, O K; Doroshenko, M E; Konyushkin, V A; Papashvili, A G; Osiko, V V

    2016-01-31

    SrF{sub 2} crystals doped with Pr{sup 3+} ions with concentrations corresponding to 0.5, 1.0 and 2.0 wt % of PrF{sub 3} are studied by selective laser excitation. The absorption and luminescence spectra of Pr{sub 3} ions are measured at a temperature of 77 K. Three types of tetragonal centres (C, E, S) with the point symmetry group C{sub 4v} and three types of cluster centres (K{sub 1}, K{sub 2}, K{sub 3}) are found. Energy level diagrams of the {sup 3}H{sub 4}, {sup 3}P{sub 1} and {sup 3}P{sub 2} terms of Pr{sup 3+} ions in SrF{sub 2} crystals are plotted for the tetragonal (C) and cluster optical centres. The lifetimes of the tetragonal C centre [τ(300 K) ∼ 112 μs, τ(77 K) ∼108 μs] and cluster centres K{sub 1} (∼43 μs), K{sub 2} (∼7 μs) and K{sub 3} (∼48 μs) are measured at 77 K for the first time. (laser spectroscopy)

  16. The Raman scattering investigation of the features of low-energy electronic excitations of the terbium ion in the KTb(WO4)2 crystal

    NASA Astrophysics Data System (ADS)

    Peschanskii, A. V.; Fomin, V. I.; Yeremenko, A. V.

    2012-06-01

    Raman scattering of light in the KTb(WO4)2 single crystal is investigated in the frequency range of 3-950 cm-1 at 5 K. The ground multiplet 7F6 of Tb3+ ion is split by the crystal field with symmetry C2, and all the multiplet components are detected. It is found that the first excited electronic quasidoublet consists of two singlet levels of different symmetry and is separated from the ground quasidoublet by ~75 cm-1. Behavior of all the detected levels is investigated in external magnetic fields H ⊥ C2 and H || C2. Spectroscopic splitting factors are determined for the ground and excited levels of the Tb3+ ion in the KTb(WO4)2 crystal. Experimental data support the view that at low temperatures the case of Ising anisotropy is realized, and the crystal under study should be considered as a system of two-level magnetic ions.

  17. The Raman scattering investigation of the features of low-energy electronic excitations of the terbium ion in the KTb(WO4)2 crystal

    NASA Astrophysics Data System (ADS)

    Peschanskii, A. V.; Fomin, V. I.; Yeremenko, A. V.

    2012-06-01

    Raman scattering of light in the KTb(WO4)2 single crystal is investigated in the frequency range of 3-950 cm-1 at 5 K. The ground multiplet 7F6 of Tb3+ ion is split by the crystal field with symmetry C2, and all the multiplet components are detected. It is found that the first excited electronic quasidoublet consists of two singlet levels of different symmetry and is separated from the ground quasidoublet by ˜75 cm-1. Behavior of all the detected levels is investigated in external magnetic fields H ⊥ C2 and H || C2. Spectroscopic splitting factors are determined for the ground and excited levels of the Tb3+ ion in the KTb(WO4)2 crystal. Experimental data support the view that at low temperatures the case of Ising anisotropy is realized, and the crystal under study should be considered as a system of two-level magnetic ions.

  18. Crystal chemistry, chemical stability, and electrochemical properties of layered oxide cathodes of lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Choi, Jeh Won

    Lithium ion batteries are now widely used as power sources in mobile electronics due to their high energy density. Layered LiCoO2 is currently employed as the cathode material in commercial lithium ion batteries, but its reversible capacity is limited to only 50% of its theoretical capacity. Co is also relatively expensive and toxic. In this regard, layered LiNi 1-y-zMnyCOzO2 cathodes have become appealing recently as they offer higher capacity, lower cost, and enhanced safety compared to the LiCoO2 cathode. This dissertation explores the chemical and structural factors and instabilities that control and limit the electrochemical performance parameters such as the capacity, cyclability, and rate capability of various layered LiNi1-y-zMnyCo zO2 cathodes. A quantitative determination of proton contents in various chemically delithiated oxide cathodes using Prompt Gamma Ray Activation Analysis (PGAA) indicates that while the delithiated layered Li1-xCoO2, Li1-xNi1/3Mn1/3Co1/3O2, and Li1-xNi1/2Mn1/2O2 have a significant amount of proton in the lattice at deep lithium extraction, orthorhombic Li 1-xMnO2, spinel Li1-xMn2O4, and olivine Li1-xFePO4 do not encounter such proton insertion. The results are complemented by mass spectrometric and thermogravimetric analysis data. The differences are attributed to the differences in the chemical instability of the various cathodes. From a systematic investigation of three series of layered LiNi 1-y-zMnyCozO2 compositions (LiNi0.5-yMn0.5-yCo2yO2, LiCo 0.5-yMn0.5-yNi2yO2, LiNi0.5-y Co0.5-yMn2yO2), those around LiNi 1/3Mn1/3Co1/3O2 are found to have optimized electrochemical performances with high reversible capacity, good cyclability, and good rate capability. The results are explained on the basis of chemical instability in the Co-rich compositions, lithium deficiency and concurrent cation disorder in the Ni-rich compositions, and existence of the impurity phase Li2MnO3 in the Mn-rich compositions. The electrochemical rate

  19. Enhanced visible light activity of nano-titanium dioxide doped with multiple ions: Effect of crystal defects

    SciTech Connect

    Jaimy, Kanakkanmavudi B.; Ghosh, Swapankumar; Gopakumar Warrier, Krishna

    2012-12-15

    Titanium dioxide photocatalysts co-doped with iron(III) and lanthanum(III) have been prepared through a modified sol-gel method. Doping with Fe{sup 3+} resulted in a relatively lower anatase to rutile phase transformation temperature, while La{sup 3+} addition reduced the crystal growth and thus retarded the phase transformation of titania nanoparticles. The presence of Fe{sup 3+} ions shifted the absorption profile of titania to the longer wavelength side of the spectrum and enhanced the visible light activity. On the other hand, La{sup 3+} addition improved the optical absorption of titania nanoparticles. Both the dopants improved the life time of excitons by proper transferring and trapping of photoexcited charges. In the present work, considerable enhancement in photocatalytic activity under visible light was achieved through synergistic effect of optimum concentrations of the two dopants and associated crystal defects. - Graphical abstract: Photocatalytic activity studies indicate a synergistic effect of dopants and crystal defects leading to an enhanced photochemical activity. Highlights: Black-Right-Pointing-Pointer An aqueous sol-gel synthesis of Fe{sup 3+} and La{sup 3+} co-doped TiO{sub 2} is being reported. Black-Right-Pointing-Pointer Optical and microstructural properties of titania were modified by co-doping. Black-Right-Pointing-Pointer Enhanced activity of titania by the crystal defects is being reported.

  20. Formation of a planar optical waveguide by mega-electron-volt He+ and P+ ions implanted in a BiB(3)O(6) crystal.

    PubMed

    Chen, F; Hu, H; Wang, K M; Teng, B; Wang, J Y; Lu, Q M; Shen, D Y

    2001-12-15

    What is believed to be the first planar optical waveguide was formed in BiB(3)O(6) (BIBO) crystal by 2.8-MeV He(+)-ion implantation with a dose of 2x10(16)ions/cm (2) and 2.8-MeV P(+)-ion implantation with a dose of 1x10(14)ions/cm (2) at room temperature. We observed 21 darks modes for the He(+)-ion-implanted BIBO waveguides and four dark modes for the P(+)-ion-implanted waveguides. The refractive-index profile of the He(+)-implanted BIBO waveguide was analyzed. The data also suggest that the BIBO waveguides formed by MeV He(+)-ion and P(+)-ion implantation differ in their developing mechanisms.

  1. Linear and nonlinear optical properties of 3-nitroaniline (m-NA) and 4-nitroaniline (p-NA) crystals: A DFT/TDDFT study

    NASA Astrophysics Data System (ADS)

    Dadsetani, M.; Omidi, A. R.

    2015-10-01

    We have studied the electronic structure and optical responses of 3-nitroaniline and 4-nitroaniline crystals within the framework of density functional theory (DFT). In addition, the excitonic effects are investigated by using the recently published bootstrap exchange-correlation kernel within the time dependent density functional theory (TDDFT) framework. Our calculations based on mBJ approximation yield the indirect band gap for both crystals, but the larger one for m-NA. Due to the excitonic effects, the TDDFT calculations gives rise to the enhanced and red-shifted spectra (compared to RPA). Due to the weak intermolecular interactions, band-structure calculations yield bands with low dispersion for both crystals. This study shows that the substituent groups play an important role in the top of valence band and the bottom of conduction band. Due to the linear structure of p-NA molecule, the highest peaks are located in the optical spectra of p-NA crystal, while m-NA has more sharp peaks, especially at lower energies. Both DFT and TDDFT calculations for the energy loss spectra show plasmon peaks around 27 and 28 eV for p-NA and m-NA, respectively. Due to the non-centrosymmetric structure of m-NA crystal, we also have reported its nonlinear spectra and the 2ω/ω intra-band and inter-band contributions to the dominant susceptibilities. Findings indicate the opposite signs for these contributions, especially at higher energies. The comparison between nonlinear spectra and the linear spectra (as a function of both ω and 2ω) reveals the significant resemblance between linear and nonlinear patterns. In addition to the reasonable agreement between our results with experimental data, this study reveals the spectral similarities between crystalline susceptibility and molecular polarizability.

  2. Current-induced giant polarization rotation using a ZnO single crystal doped with nitrogen ions

    PubMed Central

    Tate, Naoya; Kawazoe, Tadashi; Nomura, Wataru; Ohtsu, Motoichi

    2015-01-01

    Giant polarization rotation in a ZnO single crystal was experimentally demonstrated based on a novel phenomenon occurring at the nanometric scale. The ZnO crystal was doped with N+ and N2+ ions serving as p-type dopants. By applying an in-plane current using a unique arrangement of electrodes on the device, current-induced polarization rotation of the incident light was observed. From the results of experimental demonstrations and discussions, it was verified that this novel behavior originates from a specific distribution of dopants and the corresponding light–matter interactions in a nanometric space, which are allowed by the existence of such a dopant distribution. PMID:26246456

  3. Calibration of the OHREX high-resolution imaging crystal spectrometer at the Livermore electron beam ion traps

    NASA Astrophysics Data System (ADS)

    Hell, N.; Beiersdorfer, P.; Magee, E. W.; Brown, G. V.

    2016-11-01

    We report the calibration of the Orion High-Resolution X-ray (OHREX) imaging crystal spectrometer at the EBIT-I electron beam ion trap at Livermore. Two such instruments, dubbed OHREX-1 and OHREX-2, are fielded for plasma diagnostics at the Orion laser facility in the United Kingdom. The OHREX spectrometer can simultaneously house two spherically bent crystals with a radius of curvature of r = 67.2 cm. The focusing properties of the spectrometer allow both for larger distance to the source due to the increase in collected light and for observation of extended sources. OHREX is designed to cover a 2.5°-3° spectral range at Bragg angles around 51.3°. The typically high resolving powers at these large Bragg angles are ideally suited for line shape diagnostics. For instance, the nominal resolving power of the instrument (>10 000) is much higher than the effective resolving power associated with the Doppler broadening due to the temperature of the trapped ions in EBIT-I. The effective resolving power is only around 3000 at typical EBIT-I conditions, which nevertheless is sufficient to set up and test the instrument's spectral characteristics. We have calibrated the spectral range for a number of crystals using well known reference lines in the first and second order and derived the ion temperatures from these lines. We have also made use of the 50 μm size of the EBIT-I source width to characterize the spatial focusing of the spectrometer.

  4. Wigner Crystals of Na+ ions at the Surface of a Silica Hydrosol

    SciTech Connect

    Tikhonov,A.

    2007-01-01

    I used x-ray grazing incidence diffraction to measure the spatial correlations between sodium ions adsorbed with Bjerrum's density at the surface of a monodispersed 22-nm-particle colloidal silica solution stabilized by NaOH with a total bulk concentration mol/L. My findings show that the surface compact layer is in a two-dimensional crystalline state (symmetry p2), with four ions forming the unit cell and a {approx}30 Angstrom translational correlation length between sodium ions.

  5. Electronic Levels Of Cr2+ Ion Doped In II-VI Compounds Of ZnS - Crystal Field Treatment

    NASA Astrophysics Data System (ADS)

    Ivaşcu, Simona

    2012-12-01

    The aim of present paper is to report the results on the modeling of the crystal field and spin-Hamiltonian parameters of Cr2+ doped in II-VI host matrix ZnS and simulate the energy levels scheme of such system taken into account the fine interactions entered in the Hamiltonian of the system. All considered types of such interaction are expected to give information on the new peculiarities of the absorption and emission bands, as well as of non-radiative transitions between the electronic states of impurity ions. The obtained results were disscused, compared with similar obtained results in literature and with experimental data.

  6. Effect of ion beam irradiation and rubbing on the directional behavior and alignment mechanism of liquid crystals on polyimide surfaces

    SciTech Connect

    Lee, Kang-Min; Oh, Byeong-Yun; Kim, Young-Hwan; Seo, Dae-Shik

    2009-01-01

    We investigated the effects of ion beam (IB) irradiation and rubbing on the directional behavior and alignment mechanism of liquid crystals (LCs) on polyimide (PI) surfaces. We found that the LC direction follows the IB irradiation alignment direction on the PI surface regardless of whether the irradiation occurs before or after rubbing. We assumed that the LC direction depends strongly on the C-O bonds created from C=O bonds on the PI surface broken by IB irradiation and conducted an investigation of the chemical bonding state of the PI surface by x-ray photoelectron spectroscopy.

  7. Electron and positive ion emission accompanying fracture of Wint-o-Green Lifesavers and single-crystal sucrose

    SciTech Connect

    Dickinson, J.T.; Brix, L.B.; Jensen, L.C.

    1984-04-26

    It is a well-known fact that, when Wint-o-Green Lifesavers (Lifesaver is a registered trademark of Lifesaver, Inc.) are broken in air, one observes intense triboluminescence. Measurements of the emission of electrons and positive ions from the fracture of these Lifesavers under vacuum, as well as from single-crystal sucrose are reported herein. The emission of photons and radio waves during fracture under vacuum is also presented for sucrose, indicating the occurrence of a gaseous discharge in the crack tip during crack growth. Comparisons of the various emission curves are presented and discussed in terms of stress-induced charge separation.

  8. Reciprocated suppression of polymer crystallization toward improved solid polymer electrolytes: Higher ion conductivity and tunable mechanical properties

    SciTech Connect

    Bi, Sheng; Sun, Che-Nan; Zawodzinski, Thomas A.; Ren, Fei; Keum, Jong Kahk; Ahn, Suk-Kyun; Li, Dawen; Chen, Jihua

    2015-08-06

    Solid polymer electrolytes based on lithium bis(trifluoromethanesulfonyl) imide and polymer matrix were extensively studied in the past due to their excellent potential in a broad range of energy related applications. Poly(vinylidene fluoride) (PVDF) and polyethylene oxide (PEO) are among the most examined polymer candidates as solid polymer electrolyte matrix. In this paper, we study the effect of reciprocated suppression of polymer crystallization in PVDF/PEO binary matrix on ion transport and mechanical properties of the resultant solid polymer electrolytes. With electron and X-ray diffractions as well as energy filtered transmission electron microscopy, we identify and examine the appropriate blending composition that is responsible for the diminishment of both PVDF and PEO crystallites. Laslty, a three-fold conductivity enhancement is achieved along with a highly tunable elastic modulus ranging from 20 to 200 MPa, which is expected to contribute toward future designs of solid polymer electrolytes with high room-temperature ion conductivities and mechanical flexibility.

  9. Lattice location of O18 in ion implanted Fe crystals by Rutherford backscattering spectrometry, channeling and nuclear reaction analysis

    NASA Astrophysics Data System (ADS)

    Vairavel, Mathayan; Sundaravel, Balakrishnan; Panigrahi, Binaykumar

    2016-09-01

    There are contradictory theoretical predictions of lattice location of oxygen interstitial atom at tetrahedral and octahedral interstices in bcc Fe. For validating these predictions, 300 keV O18 ions with fluence of 5 × 1015 ions/cm2 are implanted into bcc Fe single crystals at room temperature and annealed at 400 °C. The Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA)/channeling measurements are carried out with 850 keV protons. The lattice location of implanted O18 is analysed using the α-particles yield from O18(p,α)N15 nuclear reaction. The tilt angular scans of α-particle yield along <110> and <100> axial directions are performed at room temperature. Lattice location of O18 is found to be at tetrahedral interstitial site by comparing the experimental scan with simulated scans using FLUX7 software.

  10. Revealing surface oxidation on the organic semi-conducting single crystal rubrene with time of flight secondary ion mass spectroscopy.

    PubMed

    Thompson, Robert J; Fearn, Sarah; Tan, Ke Jie; Cramer, Hans George; Kloc, Christian L; Curson, Neil J; Mitrofanov, Oleg

    2013-04-14

    To address the question of surface oxidation in organic electronics the chemical composition at the surface of single crystalline rubrene is spatially profiled and analyzed using Time of Flight - Secondary Ion Mass Spectroscopy (ToF-SIMS). It is seen that a uniform oxide (C42H28O) covers the surface while there is an increased concentration of peroxide (C42H28O2) located at crystallographic defects. By analyzing the effects of different primary ions, temperature and sputtering agents the technique of ToF-SIMS is developed as a valuable tool for the study of chemical composition variance both at and below the surface of organic single crystals. The primary ion beams C60(3+) and Bi3(+) are found to be most appropriate for mass spectroscopy and spatial profiling respectively. Depth profiling of the material is successfully undertaken maintaining the molecular integrity to a depth of ~5 μm using an Ar cluster ion source as the sputtering agent.

  11. Third order optical non-linear (Z-scan), birefringence, photoluminescence, mechanical and etching studies on melaminium levulinate monohydrate (MLM) single crystal for optical device applications

    NASA Astrophysics Data System (ADS)

    Sivakumar, N.; Anbalagan, G.

    2016-10-01

    Z-scan studies on the grown crystal was investigated by diode-pumped Nd; YAG laser. Nonlinear refractive index (n2) and third-order nonlinear optical susceptibility (χ3) values of MLM were found to be -1.0 × 10-8 cm2/W and 1.36 × 10-6 esu respectively. Powder X-ray diffraction analysis depicted that the crystal belongs to monoclinic system with space group P21/c. Birefringence study revealed the optical dispersion behavior of MLM crystal. Linear refractive index on (10-1) plane was measured by prism coupling technique and was estimated to be 1.4705. Hardness study was carried out along three different planes which exhibit hardness anisotropy of 41.11%. Meyer's index values of the grown crystal for the (10-1), (010) and (111) planes were found to be 2.39, 2.61 and 2.04 respectively. Etching studies on the prominent (10-1) growth plane was explained by two dimensional layer growth mechanisms. Photoluminescence study was performed on MLM crystal to explore its efficacy towards optical device fabrications.

  12. Reorientation of the crystalline planes in confined single crystal nickel nanorods induced by heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Misra, Abha; Tyagi, Pawan K.; Rai, Padmnabh; Misra, D. S.; Ghatak, Jay; Satyam, P. V.; Avasthi, D. K.

    2006-08-01

    In a recent letter Tyagi et al. [Appl. Phys. Lett. 86, 253110 (2005)] have reported the special orientation of nickel planes inside multiwalled carbon nanotubes (MWCNTs) with respect to the tube axis. Heavy ion irradiation has been performed with 1.5MeV Au2+ and 100MeV Au7+ ions on these nickel filled MWCNTs at fluences ranging from 1012to1015ions/cm2 at room temperature. Ion-induced modifications have been studied using high-resolution transmission electron microscopy. The diffraction pattern and the lattice imaging showed the presence of ion-induced planar defects on the tube walls and completely amorphized encapsulated nickel nanorods. The results are discussed in terms of thermal spike model.

  13. Measurement of Acidic Ions and Their Qualitative Effects on Snow Crystal Morphology and the Quasi-liquid Layer

    NASA Astrophysics Data System (ADS)

    Knepp, T. N.; Shepson, P. B.

    2006-12-01

    A temperature and humidity controlled chamber was constructed to observe snow crystal morphologies under various conditions and test the hypothesis that the morphology is dependent on the quasi-liquid layer's (QLL) thickness. The change in snow crystal morphology has been associated with the temperature dependent thickness of the QLL on the prism and basal facets of the forming ice. It has been proposed that the cause of a morphological change from columnar to flat plates at 263 K is a result of the QLL disappearing at this temperature. In the current experiment humid air was introduced to the top of the chamber at a constant rate by flowing air through a bubbler with the top and bottom of the chamber held at 313 K and 233 K respectively. Snow crystals were grown on the tip of an electrode held at 2000 V, positioned vertically in the chamber for the desired temperature. After the formation of an ice needle the voltage was shut off and the electrode was moved to the appropriate temperature to facilitate growth of the desired morphology on the tip of the grown needle. Sample air was drawn directly from near the region of crystal growth using a Silcosteel sampling tube. Addition of an ionizable impurity like acetic or hydrochloric acid to the bubbler air lowered the melting temperature of the ice thus forcing the QLL on the growing crystal to exist below 263 K and allowing a test of the hypothesis that the thickness of the QLL dictates the temperature at which morphological transitions occur. The morphological data was recorded using a Nikon 5400 digital camera, RH measured with a Pasco PS-2124 Dew Point sensor, and the ionic impurity concentration measured via ion chromatography. Here we discuss the preliminary results of these experiments.

  14. Growth, Optical, Dielectric and Ferroelectric Properties of Non-Linear Optical Single Crystal: Glycine-Phthalic Acid

    NASA Astrophysics Data System (ADS)

    Suresh, Sagadevan

    2016-11-01

    Single crystals of glycine-phthalic acid (GPA) were grown by slow evaporation process using aqueous solution. X-ray diffraction analysis was used to examine its cell structure and it was found that the GPA crystal corresponded to the orthorhombic system. To identify absorption range and cut-off wavelength for the GPA crystal, UV-visible spectrum was recorded. UV-visible spectroscopy was used to study the optical constants such as the refractive index, the extinction coefficient, electrical susceptibility, and optical conductivity. As a function of different frequencies and temperatures, the dielectric constant and the dielectric loss were examined. The electrical properties like plasma energy, Penn gap, Fermi energy, and polarizability were determined for the analysis of the second harmonic generation (SHG). Using the Kurtz powder technique, the SHG of the GPA crystal was studied. Investigations relating to hysteresis were carried out to ascertain the ferroelectric nature of the material.

  15. Studies on the growth and characterization of a non linear optical crystal: 3 Hydroxy Pyridinium Tartrate Mono Hydrate (3HPTMH).

    PubMed

    Balaji, J; Prabu, S; Srinivasan, P; Srinivasan, T; Velmurugan, D

    2015-06-05

    Single crystals of 3 Hydroxy Pyridinium Tartrate Mono Hydrate (3HPTMH) was synthesised and successfully grown in mixed solvent of ethanol and water by slow evaporation technique at room temperature. 3HPTMH belongs to the orthorhombic crystal system with space group P212121. The lattice parameters of 3HPTMH are a=7.4597(2)Å, b=8.7012(3)Å, c=17.8786(5)Å, V=1160.47(6)Å(3), obtained by single crystal X ray diffraction studies. Hyperpolarizability and HOMO-LUMO analysis were performed for grown crystal using DFT calculations using Gaussian 03 software. Functional groups were identified by FT-IR studies. The lower cut-off wavelength of the 3HPTMH has been identified by UV-Vis study. The thermal behavior has been studied by thermal gravimetric analysis and differential thermal analysis. The powder second harmonic generation efficiency of 3HPTMH was compared with KDP.

  16. Intrinsically incompatible crystal (ligand) field parameter sets for transition ions at orthorhombic and lower symmetry sites in crystals and their implications

    NASA Astrophysics Data System (ADS)

    Rudowicz, C.; Gnutek, P.

    2010-01-01

    Central quantities in spectroscopy and magnetism of transition ions in crystals are crystal (ligand) field parameters (CFPs). For orthorhombic, monoclinic, and triclinic site symmetry CF analysis is prone to misinterpretations due to large number of CFPs and existence of correlated sets of alternative CFPs. In this review, we elucidate the intrinsic features of orthorhombic and lower symmetry CFPs and their implications. The alternative CFP sets, which yield identical energy levels, belong to different regions of CF parameter space and hence are intrinsically incompatible. Only their ‘images’ representing CFP sets expressed in the same region of CF parameter space may be directly compared. Implications of these features for fitting procedures and meaning of fitted CFPs are categorized into negative: pitfalls and positive: blessings. As a case study, the CFP sets for Tm 3+ ions in KLu(WO 4) 2 are analysed and shown to be intrinsically incompatible. Inadvertent, so meaningless, comparisons of incompatible CFP sets result in various pitfalls, e.g., controversial claims about the values of CFPs obtained by other researchers as well as incorrect structural conclusions or faulty systematics of CF parameters across rare-earth ion series based on relative magnitudes of incompatible CFPs. Such pitfalls bear on interpretation of, e.g., optical spectroscopy, inelastic neutron scattering, and magnetic susceptibility data. An extensive survey of pertinent literature was carried out to assess recognition of compatibility problems. Great portion of available orthorhombic and lower symmetry CFP sets are found intrinsically incompatible, yet these problems and their implications appear barely recognized. The considerable extent and consequences of pitfalls revealed by our survey call for concerted remedial actions of researchers. A general approach based on the rhombicity ratio standardization may solve compatibility problems. Wider utilization of alternative CFP sets in the

  17. The interaction of a nanoscale coherent helium-ion probe with a crystal.

    PubMed

    D'Alfonso, A J; Forbes, B D; Allen, L J

    2013-11-01

    Thickness fringing was recently observed in helium ion microscopy (HIM) when imaging magnesium oxide cubes using a 40 keV convergent probe in scanning transmission mode. Thickness fringing is also observed in electron microscopy and is due to quantum mechanical, coherent, multiple elastic scattering attenuated by inelastic phonon excitation (thermal scattering). A quantum mechanical model for elastic scattering and phonon excitation correctly models the thickness fringes formed by the helium ions. However, unlike the electron case, the signal in the diffraction plane is due mainly to the channeling of ions which have first undergone inelastic thermal scattering in the first few atomic layers so that the origin of the thickness fringes is not due to coherent interference effects. This quantum mechanical model affords insight into the interaction of a nanoscale, focused coherent ion probe with the specimen and allows us to elucidate precisely what is needed to achieve atomic resolution HIM.

  18. Low temperature EPR investigation of Co2+ ion doped into rutile TiO2 single crystal: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Zerentürk, A.; Açıkgöz, M.; Kazan, S.; Yıldız, F.; Aktaş, B.

    2017-02-01

    In this paper, we present the results of X-band EPR spectra of Co2+ ion doped rutile (TiO2) which is one of the most promising memristor material. We obtained the angular variation of spectra in three mutually perpendicular planes at liquid helium (7-13 K) temperatures. Since the impurity ions have ½ effective spin and 7/2 nuclear spin, a relatively simple spin Hamiltonian containing only electronic Zeeman and hyperfine terms was utilized. Two different methods were used in theoretical analysis. Firstly, a linear regression analysis of spectra based on perturbation theory was studied. However, this approach is not sufficient for analyzing Co+2 spectra and leads to complex eigenvectors for G and A tensors due to large anisotropy of eigenvalues. Therefore, all spectra were analyzed again with exact diagonalization of spin Hamiltonian and the high accuracy eigenvalues and eigenvectors of G and A tensors were obtained by taking into account the effect of small sample misalignment from the exact crystallographic planes due to experimental conditions. Our results show that eigen-axes of g and A tensors are parallel to crystallographic directions. Hence, our EPR experiments proves that Co2+ ions substitute for Ti4+ ions in lattice. The obtained principal values of g tensor are gx=2.110(6), gy=5.890(2), gz=3.725(7) and principal values of hyperfine tensor are Ax=42.4, Ay=152.7, Az=26 (in 10-4/cm).

  19. A dead-zone free ⁴He atomic magnetometer with intensity-modulated linearly polarized light and a liquid crystal polarization rotator.

    PubMed

    Wu, T; Peng, X; Lin, Z; Guo, H

    2015-10-01

    We demonstrate an all-optical (4)He atomic magnetometer experimental scheme based on an original Bell-Bloom configuration. A single intensity-modulated linearly polarized laser beam is used both for generating spin polarization within a single (4)He vapor and probing the spin precessing under a static magnetic field. The transmitted light signal from the vapor is then phase-sensitively detected at the modulation frequency and its harmonics, which lead to the atomic magnetic resonance signals. Based on this structure, a liquid crystal is added in our magnetometer system and constitutes a polarization rotator. By controlling the voltage applied on the liquid crystal, the light linear polarization vector can be kept perpendicular with the ambient magnetic field direction, which in turn provides the maximum resonance signal amplitude. Moreover, the system exhibits a magnetic-field noise floor of about 2pT/√Hz, which is not degraded due to the presence of the liquid crystal and varying magnetic field direction. The experiment results prove that our method can eliminate the dead-zone effect, improve the system spatial isotropy, and thus be suitable in mobile applications.

  20. Investigations of the spin Hamiltonian parameters for VO2+ ions in KZnClSO4 ṡ 3H2O single crystals

    NASA Astrophysics Data System (ADS)

    Tu, Chao; Xie, Linhua; Du, Xiangrong

    2017-01-01

    The spin Hamiltonian parameters of VO2+ in KZnClSO4ṡ3H2O single crystals are calculated from the third-order perturbation formulas based on the double spin-orbit coupling model for the tetragonal transition-ion clusters in crystals with the ground state |dxy>. In the paper, both the crystal-field (CF) mechanism and the charge-transfer (CT) mechanism (double-mechanism model) are considered to calculate the spin Hamiltonian parameters. The calculated results are in agreement with the experimental data. Moreover, the calculated results show that the CT mechanism cannot be omitted for a high-valence state V4+ ions in KZnClSO4ṡ3H2O single crystals. The tetragonal field parameters are also acquired in the paper.

  1. Sulfide binding is mediated by zinc ions discovered in the crystal structure of a hydrothermal vent tubeworm hemoglobin.

    PubMed

    Flores, Jason F; Fisher, Charles R; Carney, Susan L; Green, Brian N; Freytag, John K; Schaeffer, Stephen W; Royer, William E

    2005-02-22

    Key to the remarkable ability of vestimentiferan tubeworms to thrive in the harsh conditions of hydrothermal vents are hemoglobins that permit the sequestration and delivery of hydrogen sulfide and oxygen to chemoautotrophic bacteria. Here, we demonstrate that zinc ions, not free cysteine residues, bind sulfide in vestimentiferan hemoglobins. The crystal structure of the C1 hemoglobin from the hydrothermal vent tubeworm Riftia pachyptila has been determined to 3.15 A and revealed the unexpected presence of 12 tightly bound Zn(2+) ions near the threefold axes of this D(3) symmetric hollow sphere. Chelation experiments on R. pachyptila whole-coelomic fluid and purified hemoglobins reveal a role for Zn(2+) ions in sulfide binding. Free cysteine residues, previously proposed as sulfide-binding sites in vestimentiferan hemoglobins, are found buried in surprisingly hydrophobic pockets below the surface of the R. pachyptila C1 molecule, suggesting that access of these residues to environmental sulfide is restricted. Attempts to reduce the sulfide-binding capacities of R. pachyptila hemoglobins by addition of a thiol inhibitor were also unsuccessful. These findings challenge the currently accepted paradigm of annelid hemoglobin evolution and adaptation to reducing environments.

  2. Hydrothermal synthesis and metal ions doping effects of single-crystal Mn{sub 3}O{sub 4}

    SciTech Connect

    Kuang, Lili; Dong, Ruiting; Zhang, Zhanyang; Feng, Liang; Wang, Fan Wen, Yanxuan

    2013-09-01

    Graphical abstract: - Highlights: • Dopant species and dopant/Mn molar ratio affect the shape of Mn{sub 3}O{sub 4} microcrystal. • For Cu and Ni doped Mn{sub 3}O{sub 4}, the spontaneous valence changes of dopant taken place. • An apparent change in the energy bandgap of Mn{sub 3}O{sub 4} with the metal doping. - Abstract: Synthesis of undoped and transition metal ion doped Mn{sub 3}O{sub 4} microcrystals were achieved through a simple hydrothermal route. The morphologies and structures of the obtained products were characterized using X-ray diffraction, X-ray photoemission spectroscopy and scanning electron microscopy. Results revealed that the low volume percentage of ethanol in the precursor solution limited formation of Mn{sup 2+}, while the introduction of doping ions into the precursor solution caused a direct synthesis of single phase Mn{sub 3}O{sub 4} crystals. For Cu and Ni doping ions, the spontaneous valence changes during the doping process were taken place. The possible doping mechanisms for the formation of single-phase Mn{sub 3}O{sub 4} were discussed briefly. UV–vis spectroscopic studies showed an apparent change in the energy bandgap of Mn{sub 3}O{sub 4} with the metal doping.

  3. Effect of Crystal Orientation on Self-Assembly Nanocones Formed on Tungsten Surface Induced by Helium Ion Irradiation and Annealing

    PubMed Central

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

    2016-01-01

    The self-assembly nanocone structures on the surface of polycrystalline tungsten were created by He+ ion irradiation and then annealing, and the resulting topography and morphology were characterized using atomic force microscopy and scanning electron microscopy. The cross-sectional samples of the self-assembly nanocones were prepared using an in situ–focused ion beam and then observed using transmission electron microscopy. The self-assembly nanocones were induced by the combined effect of He+ ion irradiation, the annealing process and the chromium impurity. The distribution characteristics, density and morphology of the nanocones exhibited a distinct difference relating to the crystal orientations. The highest density of the nanocones was observed on the grain surface with a (1 1 1) orientation, with the opposite for that with a (0 0 1) orientation and a medium value on the (1 0 1)-oriented grain. The size of the self-assembly nanocones increased with increasing the annealing time which met a power-law relationship. Irradiation-induced defects acted as the nucleation locations of the protrusions which attracted the migration of the tiny amount of chromium atoms. Under the action of temperature, the protrusions finally evolved into the nanocones. PMID:28335337

  4. Chemical reactions of conformationally selected 3-aminophenol molecules in a beam with Coulomb-crystallized Ca+ ions

    NASA Astrophysics Data System (ADS)

    Rösch, Daniel; Willitsch, Stefan; Chang, Yuan-Pin; Küpper, Jochen

    2014-03-01

    Many molecules exhibit multiple conformers that often easily interconvert under thermal conditions. Therefore, single conformations are difficult to isolate which renders the study of their distinct chemical reactivities challenging. We have recently reported a new experimental method for the characterization of conformer-specific effects in chemical reactions [Y.-P. Chang, K. Długołęcki, J. Küpper, D. Rösch, D. Wild, and S. Willitsch, "Specific chemical reactivities of spatially separated 3-aminophenol conformers with cold Ca+ ions," Science 342, 98-101 (2013)]. Different conformers are spatially separated using inhomogeneous electric fields and reacted with a Coulomb crystal of cold, spatially localized ions in a trap. As a first application, we studied reactions between the two conformers of 3-aminophenol and Ca+. We observed a twofold larger rate constant for the cis compared to the trans conformer which was rationalized in terms of the differences in the long-range ion-molecule interactions. The present article provides a detailed description of the new method and a full account of the experimental results as well as the accompanying theoretical calculations.

  5. Identification of carcinogen DNA adducts in human saliva by linear quadrupole ion trap/multistage tandem mass spectrometry.

    PubMed

    Bessette, Erin E; Spivack, Simon D; Goodenough, Angela K; Wang, Tao; Pinto, Shailesh; Kadlubar, Fred F; Turesky, Robert J

    2010-07-19

    DNA adducts of carcinogens derived from tobacco smoke and cooked meat were identified by liquid chromatography-electrospray ionization/multistage tandem mass spectrometry (LC-ESI/MS/MS(n)) in saliva samples from 37 human volunteers on unrestricted diets. The N-(deoxyguanosin-8-yl) (dG-C8) adducts of the heterocyclic aromatic amines 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-9H-pyrido[2,3-b]indole (AalphaC), 2-amino-3,8-dimethylmidazo[4,5-f]quinoxaline (MeIQx), and the aromatic amine, 4-aminobiphenyl (4-ABP), were characterized and quantified by LC-ESI/MS/MS(n), employing consecutive reaction monitoring at the MS(3) scan stage mode with a linear quadrupole ion trap (LIT) mass spectrometer (MS). DNA adducts of PhIP were found most frequently: dG-C8-PhIP was detected in saliva samples from 13 of 29 ever-smokers and in saliva samples from 2 of 8 never-smokers. dG-C8-AalphaC and dG-C8-MeIQx were identified solely in saliva samples of three current smokers, and dG-C8-4-ABP was detected in saliva from two current smokers. The levels of these different adducts ranged from 1 to 9 adducts per 10(8) DNA bases. These findings demonstrate that PhIP is a significant DNA-damaging agent in humans. Saliva appears to be a promising biological fluid in which to assay DNA adducts of tobacco and dietary carcinogens by selective LIT MS techniques.

  6. Identification of Carcinogen DNA Adducts in Human Saliva by Linear Quadrupole Ion Trap/Multistage Tandem Mass Spectrometry

    PubMed Central

    Bessette, Erin E.; Spivack, Simon D.; Goodenough, Angela K.; Wang, Tao; Pinto, Shailesh; Kadlubar, Fred F.; Turesky, Robert J.

    2010-01-01

    DNA adducts of carcinogens derived from tobacco smoke and cooked meat were identified, by liquid chromatography-electrospray ionization/multi-stage tandem mass spectrometry (LC-ESI/MS/MSn), in saliva samples from 37 human volunteers on unrestricted diets. The N-(deoxyguanosin-8-yl) (dG-C8) adducts of the heterocyclic aromatic amines 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP); 2-amino-9H-pyrido[2,3-b]indole (AαC); 2-amino-3,8-dimethylmidazo[4,5-f]quinoxaline (MeIQx); and the aromatic amine, 4-aminobiphenyl (4-ABP) were characterized and quantified, by LC-ESI/MS/MSn, employing consecutive reaction monitoring at the MS3 scan stage mode with a linear quadrupole ion trap (LIT) mass spectrometer (MS). DNA adducts of PhIP were found most frequently: dG-C8-PhIP was detected in saliva samples from 13 of 29 ever-smokers and in saliva samples from 2 of 8 never-smokers. dG-C8-AαC and dG-C8-MeIQx were identified solely in saliva samples of 3 current smokers, and dG-C8-4-ABP was detected in saliva from 2 current-smokers. The levels of these different adducts ranged from 1 to 9 adducts per 108 DNA bases. These findings demonstrate that PhIP is a significant DNA-damaging agent in humans. Saliva appears to be a promising biological fluid in which to assay DNA adducts of tobacco and dietary carcinogens, by selective LIT MS techniques. PMID:20443584

  7. PICKUP ION MEDIATED PLASMAS. I. BASIC MODEL AND LINEAR WAVES IN THE SOLAR WIND AND LOCAL INTERSTELLAR MEDIUM

    SciTech Connect

    Zank, G. P.; Hunana, P.; Mostafavi, P.; Goldstein, M. L.

    2014-12-20

    Pickup ions (PUIs) in the outer heliosphere and the local interstellar medium are created by charge exchange between protons and hydrogen (H) atoms, forming a thermodynamically dominant component. In the supersonic solar wind beyond >10 AU, in the inner heliosheath (IHS), and in the very local interstellar medium (VLISM), PUIs do not equilibrate collisionally with the background plasma. Using a collisionless form of Chapman-Enskog expansion, we derive a closed system of multi-fluid equations for a plasma comprised of thermal protons and electrons, and suprathermal PUIs. The PUIs contribute an isotropic scalar pressure to leading order, a collisionless heat flux at the next order, and a collisionless stress tensor at the second-order. The collisionless heat conduction and viscosity in the multi-fluid description results from a non-isotropic PUI distribution. A simpler one-fluid MHD-like system of equations with distinct equations of state for both the background plasma and the PUIs is derived. We investigate linear wave properties in a PUI-mediated three-fluid plasma model for parameters appropriate to the VLISM, the IHS, and the solar wind in the outer heliosphere. Five distinct wave modes are possible: Alfvén waves, thermal fast and slow magnetoacoustic waves, PUI fast and slow magnetoacoustic waves, and an entropy mode. The thermal and PUI acoustic modes propagate at approximately the combined thermal magnetoacoustic speed and the PUI sound speed respectively. All wave modes experience damping by the PUIs through the collisionless PUI heat flux. The PUI-mediated plasma model yields wave properties, including Alfvén waves, distinctly different from those of the standard two-fluid model.

  8. Crystal chemistry and ion-exchange properties of the layered uranyl iodate K[UO{sub 2}(IO{sub 3}){sub 3}

    SciTech Connect

    Shvareva, Tatiana Y.; Almond, Philip M.; Albrecht-Schmitt, Thomas E. . E-mail: albreth@auburn.edu

    2005-02-15

    Single crystals of the potassium uranyl iodate, K[UO{sub 2}(IO{sub 3}){sub 3}] (1), have been grown under mild hydrothermal conditions. The structure of 1 contains two-dimensional {sub {infinity}}{sup 2}[UO{sub 2}(IO{sub 3}){sub 3}]{sup 1-} sheets extending in the [ab] plane that consist of approximately linear UO{sub 2}{sup 2+} cations bound by iodate anions to yield UO{sub 7} pentagonal bipyramids. There are three crystallographically unique iodate anions, two of which bridge between uranyl cations to create sheets, and one that is monodentate and protrudes in between the layers in cavities. K{sup +} cations form long ionic contacts with oxygen atoms from the layers forming an eight-coordinate distorted dodecahedral geometry. These cations join the {sub {infinity}}{sup 2}[UO{sub 2}(IO{sub 3}){sub 3}]{sup 1-} sheets together. Ion-exchange reactions have been carried out that indicate the selective uptake of Cs{sup +} over Na{sup +} or K{sup +} by 1. Crystallographic data (193K, MoK{alpha}, {lambda}=0.71073A): 1, orthorhombic, Pbca, a=11.495(1)A, b=7.2293(7)A, c=25.394(2)A, Z=8, R(F)=1.95% for 146 parameters with 2619 reflections with I>2{sigma}(I)

  9. Piperazine as counter ion for insulin-enhancing anions [VO2(dipic-OH)]-: Synthesis, characterization and X-ray crystal structure

    NASA Astrophysics Data System (ADS)

    Ghasemi, Fatemeh; Ghasemi, Khaled; Rezvani, Ali Reza; Graiff, Claudia

    2016-01-01

    The new complex [H2Pipz][VO2(dipic-OH)]2·2H2O (1), where H2dipic-OH = 4-hydroxypyridine-2,6-dicarboxylic acid and Pipz = piperazine, was synthesized and characterized by elemental analysis, FTIR, 1H NMR, 13C NMR and UV-Vis spectroscopy and single crystal X-ray diffraction. The crystal system is triclinic with space group Pī. In this compound, piperazine is diprotonated and acts as counter ion.

  10. Optical characteristics of Er3+ ion in Er/Yb:LiNbO3 crystal: Comparison with the dissimilar effect of anti-photorefractive ions Zn2+, In3+ and Zr4+

    NASA Astrophysics Data System (ADS)

    Qian, Yannan; Wang, Rui; Wang, Biao; Xu, Chao; Xu, Wei; Xing, Lili; Xu, Yanling

    2013-11-01

    The different influences of Zn2+, In3+ and Zr4+ ions on the optical characteristics of Er3+ ion in Er/Yb:LiNbO3 crystals were discussed. An enhanced 1.54 μm emission was observed for Zr/Er/Yb:LiNbO3 crystal, but the Zn2+ tri-doping resulted in a decreased one, and the intensity of 1.54 μm emission remained about same in In/Er/Yb:LiNbO3 crystal. The populations of the green emitting 4S3/2/2H11/2 states were achieved through the three-, two- and two-phonon processes in Zn/Er/Yb:LiNbO3, In/Er/Yb:LiNbO3 and Zr/Er/Yb:LiNbO3 crystals, respectively. Zn2+ and In3+ ions affected the optical characteristics of Er3+ ion via modifying the Er3+ ion occupancy in Er/Yb:LiNbO3 crystal. The formation of ErLi2+-ErNb2- ion pairs caused by the Zn2+ and In3+ ions could increase the rate of cross relaxation process. The OH- absorption spectra showed that the incorporation of Zr4+ ions increased OH- content, which increased the probability of the nonradiative relaxation process of 4I11/2→4I13/2 (Er) in Zr/Er/Yb:LiNbO3 crystal. The J-O intensity parameters Ωt (t=2, 4 and 6), the radiative lifetime (τrad) and fluorescence branching ratio (β) in Zr/Er/Yb:LiNbO3 crystal were predicted by Judd-Ofelt theory. Füchtbauer-Ladenburg and McCumber methods were carried out to calculate the emission cross-sections at 1.54 μm emission. The gain cross-section, estimated as a function of the population inversion ratio, allowed us to evaluate a potential laser performance of Zr/Er/Yb:LiNbO3 crystal.

  11. Dynamics of Ion-Gating 2D Crystals Using a Solid Polymer Electrolyte

    NASA Astrophysics Data System (ADS)

    Li, Hua-Min; Bourdon, Buchanan; Lin, Yu-Chuan; Robinson, Joshua; Seabaugh, Alan; Fullerton, Susan; CenterLow Energy Systems Technology (Least) Team

    2015-03-01

    Ion-gating can significantly increase the static carrier density of graphene due to the formation of an electric double layer (EDL); however, the dynamics of ion-gating have not been extensively reported. A comprehensive understanding of ion dynamics is important because it establishes the timescales required to achieve EDL equilibrium, and directly affects the operating speed of devices and circuits employing electrolytic gates. Here, ion dynamics are measured on epitaxial graphene Hall-bar devices that are electrolytically gated with polyethylene oxide and lithium perchlorate. The time constants for EDL formation and dissipation are measured as a function of temperature. The measured formation time is slower than the dissipation time, because ion diffusion resulting from a concentration gradient must be opposed during EDL formation. These results quantitatively agree with COMSOL multiphysics simulations. EDL dissipation follows a stretched exponential decay described by the Kohlrausch-Williams-Watts (KWW) equation. The temperature-dependent relaxation times extracted from the KWW fit follow the Vogel-Fulcher-Tammann (VFT) temperature dependence. At temperatures approaching the glass transition temperature of the electrolyte, the relaxation times exceed several hours, demonstrating the long timescales over which the EDL can persist in the absence of a gate bias.

  12. Surface Structure and Lattice Dynamics of Alkali Halide Crystals Studied by High-Resolution Ion Scattering

    NASA Astrophysics Data System (ADS)

    Kido, Yoshiaki; Okazawa, Tetsuaki

    The rumpled surface structure and thermal lattice vibrations of KI(001) and RbI(001) were measured directly by high-resolution medium energy ion scattering (MEIS). The relaxation of interlayer distance between the top and second layer and the rumpling of the top and second layers were determined using the ion shadowing effect with an accuracy of 0.01 Å. From the displaced lattice positions determined above, we derived the dipole moments of the top- and second-layer ions self-consistently employing the polarizabilities estimated from the optical refractive index combined with the Clausius Mossotti relation. The balance between a short-range force and a long-range Coulombic one made it possible to judge the applicability of the short-range pair potentials proposed so far. We also determined the root-mean-square (rms) thermal vibration amplitudes of the bulk and the top-layer ions together with the correlations of the ions in the [001] and [101] strings by taking various kinds of scattering geometries. The results obtained were compared with those calculated from the molecular dynamics (MD) simulations based on a classical model using the dipole moments determined above and the Born Mayer type pair potential. The present MEIS results are in overall agreement with the MD simulations.

  13. Non-linear Imaging of Nanoscale Surface Defects on Alphabet Letter Shaped Colloids in a Uniformly Aligned Nematic Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Giller, Julian; Lapointe, Clayton P.; Smalyukh, Ivan I.

    2012-03-01

    The formation of defect structures on the surfaces of colloids immersed in uniformly aligned nematic liquid crystals is a phenomenon which, if better understood, could lead to advances in micro and nanoscale colloidal self assembly techniques. In this study, three photon fluorescence microscopy (3PFM) was used in conjunction with holographic optical tweezers (HOT) in order to stabilize and image surface defects on English alphabet letter shaped colloids suspended in a uniformly aligned nematic liquid crystal. This data made it possible to characterize the location and strength of these defects for a robust variety of shapes. A relationship between particle shape and angle of orientation vs the host nematic was also observed.

  14. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal recovery from aqueous solutions

    SciTech Connect

    Fish, Richard H.

    1998-01-01

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe.sup.3+ ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+, Mg.sup.2+, Al.sup.3+, and Cr.sup.3+ ions at pH 1-3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe.sup.3+ (for example, Hg.sup.2+ at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe.sup.3+ Al.sup.3+ ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads used determined are useful as well as equilibrium selectivity coefficient (K.sub.m) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe.sup.3+ ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2,6-LICAMS series of polymer pendant ligands are more selective to divalent metal ions Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+, and Mg.sup.2+, than either PS-CATS or PS-3,3-LICAMS. However, Fe.sup.3+ ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe.sup.3+, the polymer ligand is selective for Al.sup.3+, Cu.sup.2+ or Hg.sup.2+. The changing of the cavity size from two CH.sub.2 groups to six CH.sub.2 groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion

  15. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal recovery from aqueous solutions

    DOEpatents

    Fish, R.H.

    1998-11-10

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1--3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe{sup 3+}, Al{sup 3+} ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads used determined are useful as well as equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe{sup 3+} ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2,6-LICAMS series of polymer pendant ligands are more selective to divalent metal ions Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, and Mg{sup 2+}, than either PS-CATS or PS-3,3-LICAMS. However, Fe{sup 3+} ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe{sup 3+}, the polymer ligand is selective for Al{sup 3+}, Cu{sup 2+} or Hg{sup 2+}. The changing of the cavity size from two CH{sub 2} groups to six CH{sub 2} groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect

  16. The effect of 100 MeV oxygen ion on electrical and optical properties of nonlinear optical l-alanine sodium nitrate single crystals

    NASA Astrophysics Data System (ADS)

    Ahlam, M. A.; Prakash, A. P. Gnana

    2012-06-01

    Single crystals of nonlinear optical (NLO) L-alanine Sodium Nitrate (LASN) were grown by slow evaporation method. The grown crystals were irradiated by 100 MeV oxygen ions with the cumulative doses of 1Mrad, 6 Mrad and 10 Mrad. The dielectric properties, differential scanning calorimetry (DSC) and second harmonic generation (SHG) of the crystals were studied before and after irradiation. The dielectric constant was found to increase after irradiation. The DSC reveals that the melting point remains unaffected due to irradiation. The SHG efficiency of LASN was found to decrease with increase in radiation dose.

  17. Stereocomplex Crystallization of Linear Two-Armed Stereo Diblock Copolymers: Effects of Chain Directional Change, Coinitiator Moiety, and Terminal Groups.

    PubMed

    Tsuji, Hideto; Ogawa, Michiaki; Arakawa, Yuki

    2017-03-30

    Two-armed poly(l-lactide) (PLLA)-b-poly(d-lactide) (PDLA) (2-LD) copolymers with a wide-range of molecular weight were synthesized and the effect of coinitiator moiety, which functions as impurity and causes chain directional change in the middle of molecules (Effect A), and/or the additional effect of types of terminal groups (Effect B) on crystallization behavior of 2-LD copolymers were studied, in comparison with that reported for one-armed PLLA-b-PDLA (1-LD) copolymers. Formation of only stereocomplex (SC) crystallites in 2-LD and 1-LD copolymers indicates that neighboring PLLA and PDLA blocks facilitated SC crystallization and neither Effect A nor B affected the crystalline species. Effect A and/or B (both hydroxyl terminal groups) disturbed cold SC crystallization of 2-LD copolymers compared to that of 1-LD copolymers. Crystalline growth morphologies of 2-LD and 1-LD copolymers during cold SC crystallization were spherical and solid sheaf, respectively, exhibiting that crystalline growth morphology was influenced by Effects A and/or B. The melting temperature or crystalline thickness of SC crystallites were determined by number-average molecular weight per one block and not affected by Effect A or B. Maximum radial growth rates of spherulites of 2-LD copolymers compared to those of 1-LD copolymers were largely decreased by Effect A and/or B (both hydroxyl terminal groups).

  18. New tetragonal form of reaction centers from Rhodobacter sphaeroides and the involvement of a manganese ion at a crystal contact point.

    PubMed

    Uyeda, G; Cámara-Artigas, A; Williams, J C; Allen, J P

    2005-08-01

    Crystals have been obtained of wild-type reaction centers from Rhodobacter sphaeroides using manganese chloride as a precipitating agent. The crystals belong to the tetragonal space group P4(2)22, with unit-cell parameters a = b = 207.8, c = 107.5 A. The crystal structure has been determined to a resolution limit of 4.6 A using a previously determined structure of the reaction center as a molecular-replacement model. The calculated electron-density maps show the presence of a manganese ion at one of the crystal contact points bridging two symmetry-related histidine residues, suggesting that the metal plays a key role in facilitating the crystallization of the protein in this form.

  19. Field Ion Microscopy and Atom Probe Tomography of Metamorphic Magnetite Crystals

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    Magnetite has been analysed using Field Ion Microscopy (FIM) and Atom Probe Tomography (APT), highly attractive techniques for the nanoanalysis of geological materials despite the difficulties inherent in analyzing semiconducting and insulating materials. Additional information is contained in the original extended abstract.

  20. Linear ion-trap MSn with high resolution mass spectrometry reveals structural diversity of epidermal 1-O-acyl ceramide family in mouse epidermis.

    PubMed

    Lin, Meei-Hua; Miner, Jeffery; Turk, John; Hsu, Fong-Fu

    2017-02-02

    1-O-acylceramide is a new class of epidermal ceramide found in humans and mice. Here, we report ESI linear ion-trap (LIT) multiple stage mass spectrometric (MSn) approach with high resolution towards structural characterization of this lipid family isolated from mice. Molecular species desorbed as the [M + H]+ ions was subjected to LIT MS2 to yield predominately the [M + H - H2O]+ ions, followed by MS3 to cleave the 1-O-acyl residue to yield the [M + H - H2O - (1-O-fatty acid)]+ ions. The structures of the N-acyl chain and long-chain base (LCB) of the molecule were determined by MS4 on ([M + H - H2O - (1-O-fatty acid)]+) ions that yielded multiple sets of specific ions. Using this approach, isomers varied in the 1-O-acyl (from 14:0- to 26:0-O-acyl) and N-acyl chains (from 20:0- to 26:0-N-acyl) with 18:1-sphingosine as the major LCB were found for the entire family. Minor isomers consisting of 16:1- 17:1-, 18:2-, and 19:1-sphingosine LCB, with odd fatty acyl chain, or with monounsaturated N- or O- fatty acyl substituents were also identified. An estimation of more than 700 1-O-acylceramide species, largely isobaric isomers are present, underscoring the complexity of this ceramide family.