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Sample records for molecular anions sputtered

  1. Alkali metal adsorbate sputtering by molecular impact

    International Nuclear Information System (INIS)

    Moran, J.P.; Wachman, H.Y.; Trilling, L.

    1974-01-01

    An exploratory study of the sputtering by a krypton molecular beam of rubidium adsorbed at low coverage on a tungsten substrate has been described in a previous paper. An extension of this work is reported now

  2. Verification of the sputter-generated 32SFn- (n = 1-6) anions by accelerator mass spectrometry

    Science.gov (United States)

    Mane, R. G.; Surendran, P.; Kumar, Sanjay; Nair, J. P.; Yadav, M. L.; Hemalatha, M.; Thomas, R. G.; Mahata, K.; Kailas, S.; Gupta, A. K.

    2016-01-01

    Recently, we have performed systematic Secondary Ion Mass Spectrometry (SIMS) measurements at our ion source test set up and have demonstrated that gas phase 32SFn- (n = 1-6) anions for all size 'n' can be readily generated from a variety of surfaces undergoing Cs+ ion sputtering in the presence of high purity SF6 gas by employing the gas spray-cesium sputter technique. In our SIMS measurements, the isotopic yield ratio 34SFn-/32SFn- (n = 1-6) was found to be close to its natural abundance but not for all size 'n'. In order to gain further insight into the constituents of these molecular anions, ultra sensitive Accelerator Mass Spectrometry (AMS) measurements were conducted with the most abundant 32SFn- (n = 1-6) anions, at BARC-TIFR 14 UD Pelletron accelerator. The results from these measurements are discussed in this paper.

  3. Detection of sputtered molecular doubly charged anions: a comparison of secondary-ion mass spectrometry (SIMS) and accelerator mass spectrometry (AMS)

    International Nuclear Information System (INIS)

    Gnaser, Hubert; Golser, Robin; Kutschera, Walter; Priller, Alfred; Steier, Peter; Vockenhuber, Christof

    2004-01-01

    The detection of small molecular dianions by secondary-ion mass spectrometry (SIMS) and by accelerator mass spectrometry (AMS) is compared. In SIMS, the existence of these dianions can be identified safely if the total mass number of the molecule is odd and the dianion is hence detected at a half-integral mass number. The occurrence of fragmentation processes which may interfere with this scheme, is illustrated by means of the energy spectra of singly and doubly charged negative cluster ions. As compared to SIMS, AMS can rely, in addition, on the break-up of molecular species in the stripping process: this allows to monitor the simultaneous arrival of several atomic constituents with a clear energetic pattern in coincidence at the detector. This feature is exemplified for the C 10 2- dianion

  4. Simulation of carbon sputtering due to molecular hydrogen impact

    International Nuclear Information System (INIS)

    Laszlo, J.

    1993-01-01

    Simulated results are compared to experimental data on the sputtering yield of carbon due to atomic and to molecular hydrogen impact. The experimental sputtering yields of carbon (graphite) due to low energy hydrogen bombardment have been found to be higher than the simulated ones. Efforts are made to obtain high enough simulated yields by considering the formation of dimer, H 2 and D 2 molecules in the primary beam. The molecular beam model applies full neutralization and full dissociation at the surface. The simulation of sputtering yields of target materials up to Z 2 ≤ 30 is also included for the low primary energy regime for deuterium projectiles. It is found that, although the sputtering yields really tend to increase, the effect of molecule formation in the beam in itself cannot be made responsible for the deviation between measured and simulated sputtering yields. (orig.)

  5. The chemistry of molecular anions in circumstellar sources

    Energy Technology Data Exchange (ETDEWEB)

    Agúndez, Marcelino [LUTH, Observatoire de Paris-Meudon, 5 Place Jules Janssen, 92190 Meudon (France); Cernicharo, José [Departamento de Astrofísica, CAB, CSIC-INTA, Ctra. de Torrejón a Ajalvir km 4, 28850 Madrid (Spain); Guélin, Michel [Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, 38406 Saint Martin d' Héres (France)

    2015-01-22

    The detection of negatively charged molecules in the interstellar and circumstellar medium in the past four years has been one of the most impacting surprises in the area of molecular astrophysics. It has motivated the interest of astronomers, physicists, and chemists on the study of the spectroscopy, chemical kinetics, and prevalence of molecular anions in the different astronomical regions. Up to six different molecular anions have been discovered in space to date, the last one being the small ion CN{sup −}, which has been observed in the envelope of the carbon star IRC +10216 and which contrary to the other larger anions is not formed by electron attachment to CN, but through reactions of large carbon anions with nitrogen atoms. Here we briefly review the current status of our knowledge of the chemistry of molecular anions in space, with particular emphasis on the circumstellar source IRC +10216, which to date is the astronomical source harboring the largest variety of anions.

  6. Verification of the sputter-generated {sup 32}SF{sub n}{sup −} (n = 1–6) anions by accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Mane, R.G.; Surendran, P. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, Sanjay [Physics Department, Agra College Agra, Agra 282002 (India); Nair, J.P.; Yadav, M.L. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Hemalatha, M. [UM-DAE Centre for Excellence in Basic Sciences, Mumbai 400098 (India); Thomas, R.G.; Mahata, K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kailas, S. [UM-DAE Centre for Excellence in Basic Sciences, Mumbai 400098 (India); Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Gupta, A.K., E-mail: anit@tifr.res.in [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2016-01-01

    Recently, we have performed systematic Secondary Ion Mass Spectrometry (SIMS) measurements at our ion source test set up and have demonstrated that gas phase {sup 32}SF{sub n}{sup −} (n = 1–6) anions for all size ‘n’ can be readily generated from a variety of surfaces undergoing Cs{sup +} ion sputtering in the presence of high purity SF{sub 6} gas by employing the gas spray-cesium sputter technique. In our SIMS measurements, the isotopic yield ratio {sup 34}SF{sub n}{sup −}/{sup 32}SF{sub n}{sup −} (n = 1–6) was found to be close to its natural abundance but not for all size ‘n’. In order to gain further insight into the constituents of these molecular anions, ultra sensitive Accelerator Mass Spectrometry (AMS) measurements were conducted with the most abundant {sup 32}SF{sub n}{sup −} (n = 1–6) anions, at BARC-TIFR 14 UD Pelletron accelerator. The results from these measurements are discussed in this paper.

  7. Creating molecular macrocycles for anion recognition

    Directory of Open Access Journals (Sweden)

    Amar H. Flood

    2016-03-01

    Full Text Available The creation and functionality of new classes of macrocycles that are shape persistent and can bind anions is described. The genesis of triazolophane macrocycles emerges out of activity surrounding 1,2,3-triazoles made using click chemistry; and the same triazoles are responsible for anion capture. Mistakes made and lessons learnt in anion recognition provide deeper understanding that, together with theory, now provides for computer-aided receptor design. The lessons are acted upon in the creation of two new macrocycles. First, cyanostars are larger and like to capture large anions. Second is tricarb, which also favors large anions but shows a propensity to self-assemble in an orderly and stable manner, laying a foundation for future designs of hierarchical nanostructures.

  8. Molecular dynamic simulations of the sputtering of multilayer organic systems

    CERN Document Server

    Postawa, Z; Piaskowy, J; Krantzman, K; Winograd, N; Garrison, B J

    2003-01-01

    Sputtering of organic overlayers has been modeled using molecular dynamics computer simulations. The investigated systems are composed of benzene molecules condensed into one, two and three layers on an Ag left brace 1 1 1 right brace surface. The formed organic overlayers were bombarded with 4 keV Ar projectiles at normal incidence. The development of the collision cascade in the organic overlayer was investigated. The sputtering yield, mass, internal and kinetic energy distributions of ejected particles have been analyzed as a function of the thickness of the organic layer. The results show that all emission characteristics are sensitive to the variation of layer thickness. Although most of the ejected intact benzene molecules originate from the topmost layer, the emission of particles located initially in second and third layers is significant. The analysis indicates that the metallic substrate plays a dominant role in the ejection of intact organic molecules.

  9. Molecular dynamics of nanodroplet impact: The effect of the projectile’s molecular mass on sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Saiz, Fernan [Department of Chemistry, Imperial College of Science, Technology and Medicine, South Kensington, London, SW7 2A7 (United Kingdom); Gamero-Castaño, Manuel, E-mail: mgameroc@uci.edu [Department of Mechanical and Aerospace Engineering, University of California, Irvine, California, 92697 (United States)

    2016-06-15

    The impact of electrosprayed nanodroplets on ceramics at several km/s alters the atomic order of the target, causing sputtering, surface amorphization and cratering. The molecular mass of the projectile is known to have a strong effect on the impact phenomenology, and this article aims to rationalize this dependency using molecular dynamics. To achieve this goal, the article models the impact of four projectiles with molecular masses between 45 and 391 amu, and identical diameters and kinetic energies, 10 nm and 63 keV, striking a silicon target. In agreement with experiments, the simulations show that the number of sputtered atoms strongly increases with molecular mass. This is due to the increasing intensity of collision cascades with molecular mass: when the fixed kinetic energy of the projectile is distributed among fewer, more massive molecules, their collisions with the target produce knock-on atoms with higher energies, which in turn generate more energetic and larger numbers of secondary and tertiary knock-on atoms. The more energetic collision cascades intensify both knock-on sputtering and, upon thermalization, thermal sputtering. Besides enhancing sputtering, heavier molecules also increase the fraction of the projectile’s energy that is transferred to the target, as well as the fraction of this energy that is dissipated.

  10. Molecular dynamics of nanodroplet impact: The effect of the projectile’s molecular mass on sputtering

    International Nuclear Information System (INIS)

    Saiz, Fernan; Gamero-Castaño, Manuel

    2016-01-01

    The impact of electrosprayed nanodroplets on ceramics at several km/s alters the atomic order of the target, causing sputtering, surface amorphization and cratering. The molecular mass of the projectile is known to have a strong effect on the impact phenomenology, and this article aims to rationalize this dependency using molecular dynamics. To achieve this goal, the article models the impact of four projectiles with molecular masses between 45 and 391 amu, and identical diameters and kinetic energies, 10 nm and 63 keV, striking a silicon target. In agreement with experiments, the simulations show that the number of sputtered atoms strongly increases with molecular mass. This is due to the increasing intensity of collision cascades with molecular mass: when the fixed kinetic energy of the projectile is distributed among fewer, more massive molecules, their collisions with the target produce knock-on atoms with higher energies, which in turn generate more energetic and larger numbers of secondary and tertiary knock-on atoms. The more energetic collision cascades intensify both knock-on sputtering and, upon thermalization, thermal sputtering. Besides enhancing sputtering, heavier molecules also increase the fraction of the projectile’s energy that is transferred to the target, as well as the fraction of this energy that is dissipated.

  11. Molecular dynamics simulation of gold cluster growth during sputter deposition

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, J. W., E-mail: abraham@theo-physik.uni-kiel.de; Bonitz, M., E-mail: bonitz@theo-physik.uni-kiel.de [Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 15, D-24098 Kiel (Germany); Strunskus, T.; Faupel, F. [Institut für Materialwissenschaft, Lehrstuhl für Materialverbunde, Christian-Albrechts-Universität zu Kiel, Kaiserstraße 2, D-24143 Kiel (Germany)

    2016-05-14

    We present a molecular dynamics simulation scheme that we apply to study the time evolution of the self-organized growth process of metal cluster assemblies formed by sputter-deposited gold atoms on a planar surface. The simulation model incorporates the characteristics of the plasma-assisted deposition process and allows for an investigation over a wide range of deposition parameters. It is used to obtain data for the cluster properties which can directly be compared with recently published experimental data for gold on polystyrene [M. Schwartzkopf et al., ACS Appl. Mater. Interfaces 7, 13547 (2015)]. While good agreement is found between the two, the simulations additionally provide valuable time-dependent real-space data of the surface morphology, some of whose details are hidden in the reciprocal-space scattering images that were used for the experimental analysis.

  12. The effect of the molecular mass on the sputtering by electrosprayed nanodroplets

    Energy Technology Data Exchange (ETDEWEB)

    Borrajo-Pelaez, Rafael; Gamero-Castaño, Manuel, E-mail: mgameroc@uci.edu

    2015-07-30

    Highlights: • We study the effect of the molecular mass on nanodroplet sputtering of silicon. • The impact phenomenology is a strong function of the projectile’s molecular mass. • Nanodroplet sputtering intrinsically is a molecular scale phenomenon. - Abstract: Energetic bombardment of covalently bonded materials by electrosprayed nanodroplets causes sputtering and topographic changes on the surface of the target. This work investigates the influence of the projectile's molecular mass on these phenomena by sputtering single-crystal silicon wafers with a variety of liquids (molecular masses between 45.0 and 773.3 amu), and acceleration voltages. The electrosprays are characterized via time of flight to determine the charge to mass ratio of the nanodroplets which, together with the acceleration voltage, yield the impact velocity, the stagnation pressure, and the molecular kinetic energy of the projectile. The estimated range of droplet diameters is 20–79 nm, while the impact velocity, the stagnation pressure and the molecular kinetic energy range between 2.9–10 km/s, 4.7–63 GPa, and 2.1–98 eV. We find that the damage on the surface of the targets strongly depends on the molecular mass of the projectile: liquids with low molecular mass sputter significantly less and produce nanometric indentations and low surface roughness, the latter increasing moderately with stagnation pressure; in contrast, the roughness and sputtering caused by the impacts of droplets with larger molecular mass reach significantly higher values, and exhibit non-monotonic behaviors. The maximum sputtering yields for formamide, EAN, EMI-BF{sub 4}, EMI-Im, TES, and TPP are 0.20, 0.75, 1.20, 2.80, 4.00 and 2.90 silicon atoms per molecule in the projectile. These trends indicate that despite their rather large diameters, the sputtering by electrosprayed nanodroplets is intrinsically a molecular scale phenomenon.

  13. Molecular Recognition: Preparation and Characterization of Two Tripodal Anion Receptors

    Energy Technology Data Exchange (ETDEWEB)

    Shokri, Alireza; Deng, Shihu; Wang, Xue B.; Kass, Steven R.

    2014-03-01

    Two new tripodal hydroxyl-based anion receptors (1 and 2) are reported and their molecular complexes with Cl–, H2PO4 –, and OAc– along with the (M–1)– ion of 1 were characterized by negative ion photoelectron spectroscopy in the gas phase and by binding constant determinations in four solvents (i.e., CDCl3, CD2Cl2, CD3COCD3, and CD3CN). An intramolecular hydrogen bond network (HBN) in hexaol 1 was found to diminish its binding whereas the triol 2 is the strongest aliphatic hydroxyl-based receptor to date.

  14. A theoretical approach to sputtering due to molecular ion bombardment, 1

    International Nuclear Information System (INIS)

    Karashima, Shosuke; Ootoshi, Tsukuru; Kamiyama, Masahide; Kim, Pil-Hyon; Namba, Susumu.

    1981-01-01

    A shock wave model is proposed to explain theoretically the non-linear effects in sputtering phenomena by molecular ion bombardments. In this theory the sputtering processes are separated into two parts; one is due to linear effects and another is due to non-linear effects. The treatment of the linear parts is based on the statistical model by Schwarz and Helms concerning a broad range of atomic collision cascades. The non-linear parts are treated by the model of shock wave due to overlapping cascades, and useful equations to calculate the sputtering yields and the dynamical quantities in the system are derived. (author)

  15. Energy dependence of the molecular effect in sputtering

    International Nuclear Information System (INIS)

    Oliva-Florio, A.R.; Alonso, E.V.; Baragiola, R.A.; Ferron, J.; Jakas, M.M.

    1979-01-01

    Measurements are reported of sputtering yields of Au for Xe + and Xe 2 + impact in the energy range 1 to 50 keV. It was found that non-linear effects exist well outside the range predicted in a recent thermal spike model. (author)

  16. Energy dependence of the molecular effect in sputtering

    International Nuclear Information System (INIS)

    Oliva-Florio, A.R.; Alonso, E.V.; Baragiola, R.A.; Ferron, J.; Jakas, M.M.

    1979-01-01

    Measurements of sputtering yields of Au for Xe + and Xe + 2 impact in the energy range 1-50 keV are given. It was found that non-linear effects exist well outside the range predicted in a recent thermal spike model. (author)

  17. Study on low-energy sputtering near the threshold energy by molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    C. Yan

    2012-09-01

    Full Text Available Using molecular dynamics simulation, we have studied the low-energy sputtering at the energies near the sputtering threshold. Different projectile-target combinations of noble metal atoms (Cu, Ag, Au, Ni, Pd, and Pt are simulated in the range of incident energy from 0.1 to 200 eV. It is found that the threshold energies for sputtering are different for the cases of M1 < M2 and M1 ≥ M2, where M1 and M2 are atomic mass of projectile and target atoms, respectively. The sputtering yields are found to have a linear dependence on the reduced incident energy, but the dependence behaviors are different for the both cases. The two new formulas are suggested to describe the energy dependences of the both cases by fitting the simulation results with the determined threshold energies. With the study on the energy dependences of sticking probabilities and traces of the projectiles and recoils, we propose two different mechanisms to describe the sputtering behavior of low-energy atoms near the threshold energy for the cases of M1 < M2 and M1 ≥ M2, respectively.

  18. Electronic sputtering of large organic molecules and its application in bio molecular mass spectrometry

    International Nuclear Information System (INIS)

    Sundqvist, B.U.R.

    1992-01-01

    This is a review of research which has its origin in the discovery of Plasma Desorption Mass Spectrometry (PDMS). Two main fields of research have developed, namely fundamental studies of the ejection process at fast ion impact and studies of applications of the new mass spectrometric technique. In this review the emphasis will be on the process of electronic sputtering of organic solids but also applications of this process in bio molecular mass spectrometry will be discussed. (author)

  19. Effects of Hofmeister Anions on the LCST of PNIPAM as a Function of Molecular Weight

    Science.gov (United States)

    Zhang, Yanjie; Furyk, Steven; Sagle, Laura B.; Cho, Younhee; Bergbreiter, David E.; Cremer, Paul S.

    2008-01-01

    The effect of a series of sodium salts on the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide), PNIPAM, was investigated as a function of molecular weight and polymer concentration with a temperature gradient microfluidic device under a dark-field microscope. In solutions containing sufficient concentrations of kosmotropic anions, the phase transition of PNIPAM was resolved into two separate steps for higher molecular weight samples. The first step of this two step transition was found to be sensitive to the polymer’s molecular weight and solution concentration, while the second step was not. Moreover, the binding of chaotropic anions to the polymer was also influenced by molecular weight. Both sets of results could be explained by the formation of intramolecular and intermolecular hydrogen-bonding between polymer chains. By contrast, the hydrophobic hydration of the isopropyl moieties and polymer backbone was found to be unaffected by either the polymer’s molecular weight or solution concentration. PMID:18820735

  20. Investigating the Fundamentals of Molecular Depth Profiling Using Strong-field Photoionization of Sputtered Neutrals

    Science.gov (United States)

    Willingham, D.; Brenes, D. A.; Winograd, N.; Wucher, A.

    2010-01-01

    Molecular depth profiles of model organic thin films were performed using a 40 keV C60+ cluster ion source in concert with TOF-SIMS. Strong-field photoionization of intact neutral molecules sputtered by 40 keV C60+ primary ions was used to analyze changes in the chemical environment of the guanine thin films as a function of ion fluence. Direct comparison of the secondary ion and neutral components of the molecular depth profiles yields valuable information about chemical damage accumulation as well as changes in the molecular ionization probability. An analytical protocol based on the erosion dynamics model is developed and evaluated using guanine and trehalose molecular secondary ion signals with and without comparable laser photoionization data. PMID:26269660

  1. Molecular dynamics and experimental studies on deposition mechanisms of ion beam sputtering

    International Nuclear Information System (INIS)

    Fang, T.-H.; Chang, W.-J.; Lin, C.-M.; Lien, W.-C.

    2008-01-01

    Molecular dynamics (MD) simulation and experimental methods are used to study the deposition mechanism of ionic beam sputtering (IBS), including the effects of incident energy, incident angle and deposition temperature on the growth process of nickel nanofilms. According to the simulation, the results showed that increasing the temperature of substrate decreases the surface roughness, average grain size and density. Increasing the incident angle increases the surface roughness and the average grain size of thin film, while decreasing its density. In addition, increasing the incident energy decreases the surface roughness and the average grain size of thin film, while increasing its density. For the cases of simulation, with the substrate temperature of 500 K, normal incident angle and 14.6 x 10 -17 J are appropriate, in order to obtain a smoother surface, a small grain size and a higher density of thin film. From the experimental results, the surface roughness of thin film deposited on the substrates of Si(1 0 0) and indium tin oxide (ITO) decreases with the increasing sputtering power, while the thickness of thin film shows an approximately linear increase with the increase of sputtering power

  2. Effects of anion size and concentration on electrolyte invasion into molecular-sized nanopores

    International Nuclear Information System (INIS)

    Liu Ling; Chen Xi; Kim, Taewan; Han Aijie; Qiao Yu

    2010-01-01

    When an electrolyte solution is pressurized into a molecular-sized nanopore, oppositely charged ions are strongly inclined to aggregate, which effectively reduces the ion solubility to zero. Inside the restrictive confinement, a unique quasi-periodic structure is formed where the paired ion couples are periodically separated by a number of water molecules. As the anion size or ion concentration varies, the geometrical characteristics of the confined ion structure would change considerably, leading to a significant variation in the transport pressure. Both experimental and simulation results indicate that, contradictory to the prediction of conventional theory, infiltration pressure decreases as the anions become larger.

  3. Molecular tweezers with varying anions: a comparative study.

    Science.gov (United States)

    Dutt, Som; Wilch, Constanze; Gersthagen, Thomas; Talbiersky, Peter; Bravo-Rodriguez, Kenny; Hanni, Matti; Sánchez-García, Elsa; Ochsenfeld, Christian; Klärner, Frank-Gerrit; Schrader, Thomas

    2013-07-05

    Selective binding of the phosphate-substituted molecular tweezer 1a to protein lysine residues was suggested to explain the inhibition of certain enzymes and the aberrant aggregation of amyloid petide Aβ42 or α-synuclein, which are assumed to be responsible for Alzheimer's and Parkinson's disease, respectively. In this work we systematically investigated the binding of four water-soluble tweezers 1a-d (substituted by phosphate, methanephosphonate, sulfate, or O-methylenecarboxylate groups) to amino acids and peptides containing lysine or arginine residues by using fluorescence spectroscopy, NMR spectroscopy, and isothermal titration calorimetry (ITC). The comparison of the experimental results with theoretical data obtained by a combination of QM/MM and ab initio(1)H NMR shift calculations provides clear evidence that the tweezers 1a-c bind the amino acid or peptide guest molecules by threading the lysine or arginine side chain through the tweezers' cavity, whereas in the case of 1d the guest molecule is preferentially positioned outside the tweezer's cavity. Attractive ionic, CH-π, and hydrophobic interactions are here the major binding forces. The combination of experiment and theory provides deep insight into the host-guest binding modes, a prerequisite to understanding the exciting influence of these tweezers on the aggregation of proteins and the activity of enzymes.

  4. Molecular dynamics simulations of sputtering of organic overlayers by slow, large clusters

    International Nuclear Information System (INIS)

    Rzeznik, L.; Czerwinski, B.; Garrison, B.J.; Winograd, N.; Postawa, Z.

    2008-01-01

    The ion-stimulated desorption of organic molecules by impact of large and slow clusters is examined using molecular dynamics (MDs) computer simulations. The investigated system, represented by a monolayer of benzene deposited on Ag{1 1 1}, is irradiated with projectiles composed of thousands of noble gas atoms having a kinetic energy of 0.1-20 eV/atom. The sputtering yield of molecular species and the kinetic energy distributions are analyzed and compared to the results obtain for PS4 overlayer. The simulations demonstrate quite clearly that the physics of ejection by large and slow clusters is distinct from the ejection events stimulated by the popular SIMS clusters, like C 60 , Au 3 and SF 5 at tens of keV energies.

  5. Molecular dynamics simulations with electronic stopping can reproduce experimental sputtering yields of metals impacted by large cluster ions

    Science.gov (United States)

    Tian, Jiting; Zhou, Wei; Feng, Qijie; Zheng, Jian

    2018-03-01

    An unsolved problem in research of sputtering from metals induced by energetic large cluster ions is that molecular dynamics (MD) simulations often produce sputtering yields much higher than experimental results. Different from the previous simulations considering only elastic atomic interactions (nuclear stopping), here we incorporate inelastic electrons-atoms interactions (electronic stopping, ES) into MD simulations using a friction model. In this way we have simulated continuous 45° impacts of 10-20 keV C60 on a Ag(111) surface, and found that the calculated sputtering yields can be very close to the experimental results when the model parameter is appropriately assigned. Conversely, when we ignore the effect of ES, the yields are much higher, just like the previous studies. We further expand our research to the sputtering of Au induced by continuous keV C60 or Ar100 bombardments, and obtain quite similar results. Our study indicates that the gap between the experimental and the simulated sputtering yields is probably induced by the ignorance of ES in the simulations, and that a careful treatment of this issue is important for simulations of cluster-ion-induced sputtering, especially for those aiming to compare with experiments.

  6. Dynamics of gas-phase transient species studied by dissociative photodetachment of molecular anions

    OpenAIRE

    Lu, Zhou

    2007-01-01

    Gas-phase transient species, such as the CH₃CO₂ and HOCO free radicals, play important roles in combustion and environment chemistry. In this thesis work, the dynamics of these two radicals were studied by dissociative photodetachment (DPD) of the negative ions, CH₃CO₂-С and HOCO⁻, respectively. The experiments were carried out with a fast-ion-beam photoelectron-photofragment coincidence (PPC) spectrometer. Mass-selected molecular anions in a fast ion beam were intercepted by a linearly polar...

  7. Molecular Evolution of Slow and Quick Anion Channels (SLACs and QUACs/ALMTs).

    Science.gov (United States)

    Dreyer, Ingo; Gomez-Porras, Judith Lucia; Riaño-Pachón, Diego Mauricio; Hedrich, Rainer; Geiger, Dietmar

    2012-01-01

    Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant) SLAC-like and 422 (402 non-redundant) ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.

  8. Molecular evolution of slow and quick anion channels (SLACs and QUACs/ALMTs

    Directory of Open Access Journals (Sweden)

    Ingo eDreyer

    2012-11-01

    Full Text Available Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant SLAC-like and 422 (402 non-redundant ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.

  9. Sputter-deposited Mg-Al-O thin films: linking molecular dynamics simulations to experiments

    International Nuclear Information System (INIS)

    Georgieva, V; Bogaerts, A; Saraiva, M; Depla, D; Jehanathan, N; Lebelev, O I

    2009-01-01

    Using a molecular dynamics model the crystallinity of Mg x Al y O z thin films with a variation in the stoichiometry of the thin film is studied at operating conditions similar to the experimental operating conditions of a dual magnetron sputter deposition system. The films are deposited on a crystalline or amorphous substrate. The Mg metal content in the film ranged from 100% (i.e. MgO film) to 0% (i.e. Al 2 O 3 film). The radial distribution function and density of the films are calculated. The results are compared with x-ray diffraction and transmission electron microscopy analyses of experimentally deposited thin films by the dual magnetron reactive sputtering process. Both simulation and experimental results show that the structure of the Mg-Al-O film varies from crystalline to amorphous when the Mg concentration decreases. It seems that the crystalline Mg-Al-O films have a MgO structure with Al atoms in between.

  10. Molecular dynamics simulation of chemical sputtering of hydrogen atom on layer structured graphite

    International Nuclear Information System (INIS)

    Ito, A.; Wang, Y.; Irle, S.; Morokuma, K.; Nakamura, H.

    2008-10-01

    Chemical sputtering of hydrogen atom on graphite was simulated using molecular dynamics. Especially, the layer structure of the graphite was maintained by interlayer intermolecular interaction. Three kinds of graphite surfaces, flat (0 0 0 1) surface, armchair (1 1 2-bar 0) surface and zigzag (1 0 1-bar 0) surface, are dealt with as targets of hydrogen atom bombardment. In the case of the flat surface, graphene layers were peeled off one by one and yielded molecules had chain structures. On the other hand, C 2 H 2 and H 2 are dominant yielded molecules on the armchair and zigzag surfaces, respectively. In addition, the interaction of a single hydrogen isotope on a single graphene is investigated. Adsorption, reflection and penetration rates are obtained as functions of incident energy and explain hydrogen retention on layered graphite. (author)

  11. Ab initio theoretical study of dipole-bound anions of molecular complexes: (HF)3- and (HF)4- anions

    Science.gov (United States)

    Ramaekers, Riet; Smith, Dayle M. A.; Smets, Johan; Adamowicz, Ludwik

    1997-12-01

    Ab initio calculations have been performed to determine structures and vertical electron detachment energy (VDE) of the hydrogen fluoride trimer and tetramer anions, (HF)3- and (HF)4-. In these systems the excess electron is bound by the dipole field of the complex. It was determined that, unlike the neutral complexes which prefer the cyclic structures, the equilibrium geometries of the anions have "zig-zag" shapes. For both complexes the predicted VDEs are positive [210 meV and 363 meV for (HF)3- and (HF)4-, respectively], indicating that the anions are stable systems with respect to the vertical electron detachment. These results were obtained at the coupled-cluster level of theory with single, double and triple excitations [CCSD(T) method; the triple-excitation contribution in this method is calculated approximately using the perturbation approach] with the anion geometries obtained using the second-order Møller-Plesset perturbation theory (MP2) method. The same approach was also used to determine the adiabatic electron affinities (AEA) of (HF)3 and (HF)4. In addition to the electronic contribution, we also calculated the contributions (using the harmonic approximation) resulting from different zero-point vibration energies of the neutral and anionic clusters. The calculations predicted that while the AEA of (HF)3 is positive (44 meV), the AEA for (HF)4 is marginally negative (-16 meV). This suggests that the (HF)3- anion should be a stable system, while the (HF)4- is probably metastable.

  12. Monte Carlo simulations of silicon sputtering by argon ions and an approach for comparison with molecular dynamic results

    Energy Technology Data Exchange (ETDEWEB)

    Feder, Rene; Frost, Frank; Mayr, Stefan G.; Neumann, Horst; Bundesmann, Carsten [Leibniz-Institut fuer Oberflaechenmodifizierung e.V., Leipzig (Germany)

    2012-07-01

    Ion beam sputter processes deliver some intrinsic features influencing the growing film properties. Utilisation of these features needs to know how primary ion properties and geometrical process conditions influence the energy and spatial distribution of the sputtered and scattered particles. Beside complex experiments simulations are helpful to explain the correlation between primary parameters and thin film properties. The paper presents first results of two simulation codes with completely different approaches: Monte Carlo (MC) calculations with help of the well known TRIM.SP code and Molecular Dynamics calculations with an in-house developed code. First results of both simulation principles are compared for Argon ion bombardment on a Silicon target. Furthermore, a special experimental setup is outlined for validation of modelling. The setup allows the variation of ion beam parameters (ion species, ion energy, ion incidence angle on the target) and the measurement of the properties of sputtered and scattered particles.

  13. Molecular weight changes induced in an anionic polydimethylsiloxane by gamma irradiation in vacuum

    International Nuclear Information System (INIS)

    Satti, Angel J.; Andreucetti, Noemi A.; Ciolino, Andres E.; Vitale, Cristian; Sarmoria, Claudia; Valles, Enrique M.

    2010-01-01

    An anionic almost monodisperse linear polydimethylsiloxane (PDMS) was subjected to gamma irradiation under vacuum at room temperature. The molecular weight changes induced by the radiation process have been investigated using size exclusion chromatography (SEC) with refraction index (RI) and multi angle laser light scattering (MALLS) detectors, to obtain the number and weight average molecular weights of the irradiated samples. The analysis of the data indicates that crosslinking reactions predominated over scission reactions. The results obtained by an SEC-RI have confirmed the presence of small, but measurable amounts of scission. A previously developed mathematical model of the irradiation process that accounts for simultaneous scission and crosslinking and allows for both H- and Y-crosslinks, fitted well the measured molecular weight data. This prediction is in accordance with the experimental data obtained by 29 Si-Nuclear Magnetic Resonance spectroscopy (NMR) and previously reported data for commercial linear PDMS ().

  14. Sensitivity of ion-induced sputtering to the radial distribution of energy transfers: A molecular dynamics study

    International Nuclear Information System (INIS)

    Mookerjee, S.; Khan, S. A.; Roy, A.; Beuve, M.; Toulemonde, M.

    2008-01-01

    Using different models for the deposition of energy on the lattice and a classical molecular dynamics approach to the subsequent transport, we evaluate how the details of the energy deposition model influence sputtering yield from a Lennard-Jones target irradiated with a MeV/u ion beam. Two energy deposition models are considered: a uniform, instantaneous deposition into a cylinder of fixed radius around the projectile ion track, used in earlier molecular dynamics and fluid dynamics simulations of sputtering yields; and an energy deposition distributed in time and space based on the formalism developed in the thermal spike model. The dependence of the sputtering yield on the total energy deposited on the target atoms is very sensitive to the energy deposition model. To clarify the origin of this strong dependence, we explore the role of the radial expansion of the electronic system prior to the transfer of its energy to the lattice. The results imply that observables such as the sputtering yield may be used as signatures of the fast electron-lattice energy transfer in the electronic energy-loss regime, and indicate the need for more experimental and theoretical investigations of these processes

  15. Electronic sputtering

    International Nuclear Information System (INIS)

    Johnson, R.E.

    1989-01-01

    Electronic sputtering covers a range of phenomena from electron and photon stimulated desorption from multilayers to fast heavy ion-induced desorption (sputtering) of biomolecules. In this talk the author attempted. Therefore, to connect the detailed studies of argon ejection from solid argon by MeV ions and keV electrons to the sputtering of low temperatures molecular ices by MeV ions then to biomolecule ejection from organic solids. These are related via changing (dE/dx) e , molecular size, and transport processes occurring in materials. In this regard three distinct regions of (dE/dx) e have been identified. Since the talk this picture has been made explicit using a simple spike model for individual impulsive events in which spike interactions are combined linearly. Since that time also the molecular dynamics programs (at Virginia and Uppsala) have quantified both single atom and dimer processes in solid Ar and the momentum transport in large biomolecule sputtering. 5 refs

  16. Synthesis of Novel Hydrocarbon Soluble Multifunctional Anionic Initiators: Tools for Synthesis of Novel Dendrimer and Molecular Brush Polymer Architectures

    Science.gov (United States)

    2015-02-09

    Synthesis of Novel Dendrimer and Molecular Brush Polymer Architectures. Research Area:7.4 The views, opinions and/or findings contained in this report...journals: Final Report: Synthesis of Novel Hydrocarbon Soluble Multifunctional Anionic Initiators: Tools for Synthesis of Novel Dendrimer and Molecular

  17. Molecular dynamics simulation of temperature effects on deposition of Cu film on Si by magnetron sputtering

    Science.gov (United States)

    Zhu, Guo; Sun, Jiangping; Zhang, Libin; Gan, Zhiyin

    2018-06-01

    The temperature effects on the growth of Cu thin film on Si (0 0 1) in the context of magnetron sputtering deposition were systematically studied using molecular dynamics (MD) method. To improve the comparability of simulation results at varying temperatures, the initial status data of incident Cu atoms used in all simulations were read from an identical file via LAMMPS-Python interface. In particular, crystalline microstructure, interface mixing and internal stress of Cu thin film deposited at different temperatures were investigated in detail. With raising the substrate temperature, the interspecies mixed volume and the proportion of face-centered cubic (fcc) structure in the deposited film both increased, while the internal compressive stress decreased. It was found that the fcc structure in the deposited Cu thin films was 〈1 1 1〉 oriented, which was reasonably explained by surface energy minimization and the selectivity of bombardment energy to the crystalline planes. The quantified analysis of interface mixing revealed that the diffusion of Cu atoms dominated the interface mixing, and the injection of incident Cu atoms resulted in the densification of phase near the film-substrate interface. More important, the distribution of atomic stress indicated that the compressive stress was mainly originated from the film-substrate interface, which might be attributed to the densification of interfacial phase at the initial stage of film deposition.

  18. Molecular boxes on a molecular printboard: encapsulation of anionic dyes in immobilized dendrimers

    NARCIS (Netherlands)

    Onclin, S.; Huskens, Jurriaan; Ravoo, B.J.; Reinhoudt, David

    2005-01-01

    Fifth-generation poly(propylene imine) dendrimers, modified with 64 apolar adamantyl groups, have been immobilized on cyclodextrin host monolayers (molecular printboards) on glass by supramolecular microcontact printing. The immobilized dendrimers retain their guest-binding properties and function

  19. Diffusion of hydrogen, hydrogen sulfide and large molecular weight anions in bentonite

    International Nuclear Information System (INIS)

    Eriksen, T.E.; Jacobsson, A.

    1982-01-01

    The diffusivities of HS - and H 2 have been determined from profile analysis and steady state transport experiments. The diffusivity of HS - was found to be 9x10 - 12 and 4x10xsec 1 in MX-80 and Erbsloeh bentonite respectively. The results are in fair agreement with the results earlier obtained for Cl - and I - . The H 2 diffusivity calculated from steady state transport was found to be surprisingly low (3.6x10 - 12 m 2 xsec - 1 ). Various heavy anions with molecular weights 290-30x10 3 were found to migrate through MX-80 bentonite with diffusivities in the range (2,1-0,75)x10 - 15 m 2 xsec - 1 . (Author)

  20. Characterization of Low-Molecular-Weight Heparins by Strong Anion-Exchange Chromatography.

    Science.gov (United States)

    Sadowski, Radosław; Gadzała-Kopciuch, Renata; Kowalkowski, Tomasz; Widomski, Paweł; Jujeczka, Ludwik; Buszewski, Bogusław

    2017-11-01

    Currently, detailed structural characterization of low-molecular-weight heparin (LMWH) products is an analytical subject of great interest. In this work, we carried out a comprehensive structural analysis of LMWHs and applied a modified pharmacopeial method, as well as methods developed by other researchers, to the analysis of novel biosimilar LMWH products; and, for the first time, compared the qualitative and quantitative composition of commercially available drugs (enoxaparin, nadroparin, and dalteparin). For this purpose, we used strong anion-exchange (SAX) chromatography with spectrophotometric detection because this method is more helpful, easier, and faster than other separation techniques for the detailed disaccharide analysis of new LMWH drugs. In addition, we subjected the obtained results to statistical analysis (factor analysis, t-test, and Newman-Keuls post hoc test).

  1. Toward Molecular Magnets of Organic Origin via Anion-π Interaction Involving m-Aminyl Diradical: A Theoretical Study

    DEFF Research Database (Denmark)

    Bhattacharya, Debojit; Shil, Suranjan; Misra, Anirban

    2016-01-01

    Here we study a set of novel magnetic organic molecular species with different halide ions (fluoride, chloride, bromide) absorbed ∼2 Å above or below the center of an aromatic π-ring in an m-aminyl diradical. Focus is on the nature of anion-π interaction and its impact on magnetic properties, spe...

  2. Revisiting imidazolium based ionic liquids: Effect of the conformation bias of the [NTf2] anion studied by molecular dynamics simulations

    Science.gov (United States)

    Neumann, Jan; Golub, Benjamin; Odebrecht, Lisa-Marie; Ludwig, Ralf; Paschek, Dietmar

    2018-05-01

    We study ionic liquids composed of 1-alkyl-3-methylimidazolium cations and bis(trifluoromethyl-sulfonyl)imide anions ([CnMIm][NTf2]) with varying chain-length n = 2, 4, 6, 8 by using molecular dynamics simulations. We show that a reparametrization of the dihedral potentials as well as charges of the [NTf2] anion leads to an improvement of the force field model introduced by Köddermann, Paschek, and Ludwig [ChemPhysChem 8, 2464 (2007)] (KPL-force field). A crucial advantage of the new parameter set is that the minimum energy conformations of the anion (trans and gauche), as deduced from ab initio calculations and Raman experiments, are now both well represented by our model. In addition, the results for [CnMIm][NTf2] show that this modification leads to an even better agreement between experiment and molecular dynamics simulation as demonstrated for densities, diffusion coefficients, vaporization enthalpies, reorientational correlation times, and viscosities. Even though we focused on a better representation of the anion conformation, also the alkyl chain-length dependence of the cation behaves closer to the experiment. We strongly encourage to use the new NGOLP (Neumann, Golub, Odebrecht, Ludwig, Paschek) force field for the [NTf2] anion instead of the earlier KPL parameter set for computer simulations aiming to describe the thermodynamics, dynamics, and also structure of imidazolium-based ionic liquids.

  3. Sputtering of silicon and glass substrates with polyatomic molecular ion beams generated from ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, Mitsuaki, E-mail: m-takeuchi@kuee.kyoto-u.ac.jp; Hoshide, Yuki; Ryuto, Hiromichi; Takaoka, Gikan H. [Photonics and Electronics Science and Engineering Center, Kyoto University, Kyotodaigaku-Katsura, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2016-03-15

    The effect of irradiating 1-ethyl-3-methylimidazolium positive (EMIM{sup +}) or dicyanamide negative (DCA{sup –}) ion beams using an ionic liquid ion source was characterized concerning its sputtering properties for single crystalline Si(100) and nonalkaline borosilicate glass substrates. The irradiation of the DCA{sup –} ion beam onto the Si substrate at an acceleration voltage of 4 and 6 kV exhibited detectable sputtered depths greater than a couple of nanometers with an ion fluence of only 1 × 10{sup 15} ions/cm{sup 2}, while the EMIM{sup +} ion beam produced the same depths with an ion fluence 5 × 10{sup 15} ions/cm{sup 2}. The irradiation of a 4 kV DCA{sup –} ion beam at a fluence of 1 × 10{sup 16} ions/cm{sup 2} also yields large etching depths in Si substrates, corresponding to a sputtering yield of Si/DCA{sup – }= 10, and exhibits a smoothed surface roughness of 0.05 nm. The interaction between DCA{sup –} and Si likely causes a chemical reaction that relates to the high sputtering yield and forms an amorphous C-N capping layer that results in the smooth surface. Moreover, sputtering damage by the DCA{sup –} irradiation, which was estimated by Rutherford backscattering spectroscopy with the channeling technique, was minimal compared to Ar{sup +} irradiation at the same condition. In contrast, the glass substrates exhibited no apparent change in surface roughnesses when sputtered by the DCA{sup –} irradiation compared to the unirradiated glass substrates.

  4. Solar system sputtering

    Science.gov (United States)

    Tombrello, T. A.

    1982-01-01

    The sites and materials involved in solar system sputtering of planetary surfaces are reviewed, together with existing models for the processes of sputtering. Attention is given to the interaction of the solar wind with planetary atmospheres in terms of the role played by the solar wind in affecting the He-4 budget in the Venus atmosphere, and the erosion and differentiation of the Mars atmosphere by solar wind sputtering. The study is extended to the production of isotopic fractionation and anomalies in interplanetary grains by irradiation, and to erosion effects on planetary satellites with frozen volatile surfaces, such as with Io, Europa, and Ganymede. Further measurements are recommended of the molecular form of the ejected material, the yields and energy spectra of the sputtered products, the iosotopic fractionation sputtering causes, and the possibility of electronic sputtering enhancement with materials such as silicates.

  5. Dansyl-labeled anionic amphiphile with a hexadecanoic carbon chain: Synthesis and detection for shape transitions in organized molecular assemblies

    Science.gov (United States)

    Gao, Lining; Xia, Huiyun; Wang, Xiaoman; Li, Li; Chen, Huaxin

    2015-03-01

    The probing properties of a new fluorophore-labeled anionic surfactant, sodium 16-(N-dansyl)aminocetylate (16-DAN-ACA) were investigated systematically in molecular assemblies, especially in the transitions between micelles and vesicles. 16-DAN-ACA can efficiently differentiate the two different aggregate types in mixed cationic and anionic surfactant systems. The fluorescence anisotropy of 16-DAN-ACA was found to be sensitive for directly detecting the micellar growth in micelles containing oppositely charged surfactants; both cationic cetyltrimethylammonium bromide (CTAB) systems and anionic sodium dodecyl sulfate (SDS) systems were studied. The results indicated that the 16-DAN-ACA is a good fluorescent probe for differentiating the different aggregates, and even more can be used to detect the micellar growth.

  6. Photoelectron angular distributions for states of any mixed character: An experiment-friendly model for atomic, molecular, and cluster anions

    International Nuclear Information System (INIS)

    Khuseynov, Dmitry; Blackstone, Christopher C.; Culberson, Lori M.; Sanov, Andrei

    2014-01-01

    We present a model for laboratory-frame photoelectron angular distributions in direct photodetachment from (in principle) any molecular orbital using linearly polarized light. A transparent mathematical approach is used to generalize the Cooper-Zare central-potential model to anionic states of any mixed character. In the limit of atomic-anion photodetachment, the model reproduces the Cooper-Zare formula. In the case of an initial orbital described as a superposition of s and p-type functions, the model yields the previously obtained s-p mixing formula. The formalism is further advanced using the Hanstorp approximation, whereas the relative scaling of the partial-wave cross-sections is assumed to follow the Wigner threshold law. The resulting model describes the energy dependence of photoelectron anisotropy for any atomic, molecular, or cluster anions, usually without requiring a direct calculation of the transition dipole matrix elements. As a benchmark case, we apply the p-d variant of the model to the experimental results for NO − photodetachment and show that the observed anisotropy trend is described well using physically meaningful values of the model parameters. Overall, the presented formalism delivers insight into the photodetachment process and affords a new quantitative strategy for analyzing the photoelectron angular distributions and characterizing mixed-character molecular orbitals using photoelectron imaging spectroscopy of negative ions

  7. Photoelectron angular distributions for states of any mixed character: An experiment-friendly model for atomic, molecular, and cluster anions

    Science.gov (United States)

    Khuseynov, Dmitry; Blackstone, Christopher C.; Culberson, Lori M.; Sanov, Andrei

    2014-09-01

    We present a model for laboratory-frame photoelectron angular distributions in direct photodetachment from (in principle) any molecular orbital using linearly polarized light. A transparent mathematical approach is used to generalize the Cooper-Zare central-potential model to anionic states of any mixed character. In the limit of atomic-anion photodetachment, the model reproduces the Cooper-Zare formula. In the case of an initial orbital described as a superposition of s and p-type functions, the model yields the previously obtained s-p mixing formula. The formalism is further advanced using the Hanstorp approximation, whereas the relative scaling of the partial-wave cross-sections is assumed to follow the Wigner threshold law. The resulting model describes the energy dependence of photoelectron anisotropy for any atomic, molecular, or cluster anions, usually without requiring a direct calculation of the transition dipole matrix elements. As a benchmark case, we apply the p-d variant of the model to the experimental results for NO- photodetachment and show that the observed anisotropy trend is described well using physically meaningful values of the model parameters. Overall, the presented formalism delivers insight into the photodetachment process and affords a new quantitative strategy for analyzing the photoelectron angular distributions and characterizing mixed-character molecular orbitals using photoelectron imaging spectroscopy of negative ions.

  8. Molecular evidence for an involvement of organic anion transporters (OATs) in aristolochic acid nephropathy

    International Nuclear Information System (INIS)

    Bakhiya, Nadiya; Arlt, Volker M.; Bahn, Andrew; Burckhardt, Gerhard; Phillips, David H.; Glatt, Hansruedi

    2009-01-01

    Aristolochic acid (AA), present in Aristolochia species, is the major causative agent in the development of severe renal failure and urothelial cancers in patients with AA nephropathy. It may also be a cause of Balkan endemic nephropathy. Epithelial cells of the proximal tubule are the primary cellular target of AA. To study whether organic anion transporters (OATs) expressed in proximal tubule cells are involved in uptake of AA, we used human epithelial kidney (HEK293) cells stably expressing human (h) OAT1, OAT3 or OAT4. AA potently inhibited the uptake of characteristic substrates, p-aminohippurate for hOAT1 and estrone sulfate for hOAT3 and hOAT4. Aristolochic acid I (AAI), the more cytotoxic and genotoxic AA congener, exhibited high affinity for hOAT1 (K i = 0.6 μM) as well as hOAT3 (K i = 0.5 μM), and lower affinity for hOAT4 (K i = 20.6 μM). Subsequently, AAI-DNA adduct formation (investigated by 32 P-postlabelling) was used as a measure of AAI uptake. Significantly higher levels of adducts occurred in hOAT-expressing cells than in control cells: this effect was abolished in the presence of the OAT inhibitor probenecid. In Xenopus laevis oocytes hOAT-mediated efflux of p-aminohippurate was trans-stimulated by extracellular AA, providing further molecular evidence for AA translocation by hOATs. Our study indicates that OATs can mediate the uptake of AA into proximal tubule cells and thereby participate in kidney cell damage by this toxin.

  9. Molecular dynamics investigation of the influence of anionic and zwitterionic interfaces on antimicrobial peptides' structure: implications for peptide toxicity and activity

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Kaznessis, Yiannis N

    2006-01-01

    Molecular dynamics simulations of three related helical antimicrobial peptides have been carried out in zwitterionic diphosphocholine (DPC) micelles and anionic sodiumdodecylsulfate (SDS) micelles. These systems can be considered as model mammalian and bacterial membrane interfaces, respectively...

  10. A Molecular Precursor to Phosphaethyne and Its Application in Synthesis of the Aromatic 1,2,3,4-Phosphatriazolate Anion

    Energy Technology Data Exchange (ETDEWEB)

    Transue, Wesley J.; Velian, Alexandra; Nava, Matthew; Martin-Drumel, Marie-Aline; Womack, Caroline C.; Jiang, Jun; Hou, Gao-Lei; Wang, Xue-Bin; McCarthy, Michael C.; Field, Robert W.; Cummins, Christopher C.

    2016-06-01

    Dibenzo-7-phosphanorbornadiene Ph3PC(H)PA (1, A = C14H10, anthracene) is reported as a molecular precursor to phosphaethyne (HC≡P), produced together with anthracene and triphenylphosphine. HCP generated by thermolysis of 1 has been characterized by molecular beam mass spectrometry (MBMS), laser-induced fluorescence (LIF), microwave spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. In toluene, fragmentation of 1 has been found to proceed with activation parameters of ΔH = 25.5 kcal/mol and ΔS = ₋2.43 e.u., and is accompanied by formation of an orange insoluble precipitate. Results from computational studies of the mechanism of HCP generation are in good agreement with experimental data. This high temperature method of HCP generation has pointed to new reaction chemistry with azide anion to produce the 1,2,3,4-phosphatriazolate anion, HCPN3- , for which structural data have been obtained in a single-crystal Xray diffraction study. Negative ion photoelectron spectroscopy has shown the adiabatic detachment energy for this anion to be 3.555(10) eV. The aromaticity of HCPN3- has been assessed using nucleus-independent chemical shift (NICS), quantum theory of atoms in molecules (QTAIM), and natural bond orbital (NBO) methods.

  11. Influence of hydrogen bond accepting ability of anions on the adsorption performance of ionic liquid surface molecularly imprinted polymers.

    Science.gov (United States)

    Zhu, Guifen; Gao, Xia; Wang, Xiaolong; Wang, Jianji; Fan, Jing

    2018-01-12

    To illuminate the influence mechanism of anionic structure of ionic liquids (ILs) on the adsorption performance of surface molecularly imprinted polymers (MIPs), in this work, six newly designed MIPs were prepared on the surface of amino-poly(styrene-divinylbenzene) particles by using imidazolium ILs with the same cation [C 4 mim] + but different anions (Cl, CH 3 SO 3 , PF 6 , BF 4 , C 4 F 7 O 2 , C 4 F 9 SO 3 ) as template molecules, methacrylic acid as functional monomer, and ethylene dimethacrylate as cross-linker. The resulting MIP materials were characterized by IR and SEM, and the influence of hydrogen bond accepting ability of anions on the adsorption performance of the MIPs for the ILs was investigated in acetonitrile. It was found that adsorption capacity of the MIPs towards the ILs decreased in the order MIP [C4mim][Cl]  > MIP [C4mim][C4F7O2]  ≥ MIP [C4mim][BF4] and MIP [C4mim][CH3SO3]  > MIP [C4mim][C4F9SO3]  > MIP [C4mim][PF6] , which is in good agreement with the ability of anions of the ILs to form hydrogen bonds. Ultraviolet, 1 H-NMR and 35 Cl-NMR spectroscopy was then used to study the interactions of anions of the ILs with the functional monomer. It was found that the hydrogen bond interaction between anions of the ILs and acidic proton of the functional monomer was the main driving force for the high adsorption selectivity of the imprinted polymers, and the stronger hydrogen bond interaction indicates higher binding capacity and higher selectivity of the polymers towards the ILs. It was also verified that the ILs with stronger hydrogen bond accepting ability of anions could be selectively extracted by the corresponding IL-MIPs. These results may provide new insight into the recognition mechanism of MIPs for ILs, and are also useful for the rational design of this new class of imprinting materials. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Sputtering of copper atoms by keV atomic and molecular ions A comparison of experiment with analytical and computer based models

    CERN Document Server

    Gillen, D R; Goelich,

    2002-01-01

    Non-resonant multiphoton ionisation combined with quadrupole and time-of-flight analysis has been used to measure energy distributions of sputtered copper atoms. The sputtering of a polycrystalline copper target by 3.6 keV Ar sup + , N sup + and CF sub 2 sup + and 1.8 keV N sup + and CF sub 2 sup + ion bombardment at 45 deg. has been investigated. The linear collision model in the isotropic limit fails to describe the high energy tail of the energy distributions. However the TRIM.SP computer simulation has been shown to provide a good description. The results indicate that an accurate description of sputtering by low energy, molecular ions requires the use of computer simulation rather than analytical approaches. This is particularly important when considering plasma-surface interactions in plasma etching and deposition systems.

  13. Comparative investigation on cation-cation (Al-Sn) and cation-anion (Al-F) co-doping in RF sputtered ZnO thin films: Mechanistic insight

    Energy Technology Data Exchange (ETDEWEB)

    Mallick, Arindam; Basak, Durga, E-mail: sspdb@iacs.res.in

    2017-07-15

    Highlights: • Comparative study on Al, Al-Sn and Al-F doped ZnO films has been carried out. • High transparent Al-F co-doped film shows three times enhanced carrier density. • Al-F co-doped film shows larger carrier relaxation time. • Al-Sn co-doped films shows carrier transport dominated by impurity scattering. • Al-F co-doped ZnO film can be applied as transparent electrode. - Abstract: Herein, we report a comparative mechanistic study on cation-cation (Al-Sn) and cation-anion (Al-F) co-doped nanocrystalline ZnO thin films grown on glass substrate by RF sputtering technique. Through detailed analyses of crystal structure, surface morphology, microstructure, UV-VIS-NIR transmission-reflection and electrical transport property, the inherent characteristics of the co-doped films were revealed and compared. All the nanocrystalline films retain the hexagonal wurtzite structure of ZnO and show transparency above 90% in the visible and NIR region. As opposed to expectation, Al-Sn (ATZO) co-doped film show no enhanced carrier concentration consistent with the probable formation of SnO{sub 2} clusters supported by the X-ray photoelectron spectroscopy study. Most interestingly, it has been found that Al-F (AFZO) co-doped film shows three times enhanced carrier concentration as compared to Al doped and Al-Sn co-doped films attaining a value of ∼9 × 10{sup 20} cm{sup −3} due to the respective cation and anion substitution. The carrier relaxation time increases in AFZO while it decreases significantly for ATZO film consistent with the concurrence of the impurity scattering in the latter.

  14. Vibrational signatures of cation-anion hydrogen bonding in ionic liquids: a periodic density functional theory and molecular dynamics study.

    Science.gov (United States)

    Mondal, Anirban; Balasubramanian, Sundaram

    2015-02-05

    Hydrogen bonding in alkylammonium based protic ionic liquids was studied using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. Normal-mode analysis within the harmonic approximation and power spectra of velocity autocorrelation functions were used as tools to obtain the vibrational spectra in both the gas phase and the crystalline phases of these protic ionic liquids. The hydrogen bond vibrational modes were identified in the 150-240 cm(-1) region of the far-infrared (far-IR) spectra. A blue shift in the far-IR mode was observed with an increasing number of hydrogen-bonding sites on the cation; the exact peak position is modulated by the cation-anion hydrogen bond strength. Sub-100 cm(-1) bands in the far-IR spectrum are assigned to the rattling motion of the anions. Calculated NMR chemical shifts of the acidic protons in the crystalline phase of these salts also exhibit the signature of cation-anion hydrogen bonding.

  15. Synergistic effect of dicarbollide anions in liquid-liquid extraction: a molecular dynamics study at the octanol-water interface.

    Science.gov (United States)

    Chevrot, G; Schurhammer, R; Wipff, G

    2007-04-28

    We report a molecular dynamics study of chlorinated cobalt bis(dicarbollide) anions [(B(9)C(2)H(8)Cl(3))(2)Co](-)"CCD(-)" in octanol and at the octanol-water interface, with the main aim to understand why these hydrophobic species act as strong synergists in assisted liquid-liquid cation extraction. Neat octanol is quite heterogeneous and is found to display dual solvation properties, allowing to well solubilize CCD(-), Cs(+) salts in the form of diluted pairs or oligomers, without displaying aggregation. At the aqueous interface, octanol behaves as an amphiphile, forming either monolayers or bilayers, depending on the initial state and confinement conditions. In biphasic octanol-water systems, CCD(-) anions are found to mainly partition to the organic phase, thus attracting Cs(+) or even more hydrophilic counterions like Eu(3+) into that phase. The remaining CCD(-) anions adsorb at the interface, but are less surface active than at the chloroform interface. Finally, we compare the interfacial behavior of the Eu(BTP)(3)(3+) complex in the absence and in the presence of CCD(-) anions and extractant molecules. It is found that when the CCD(-)'s are concentrated enough, the complex is extracted to the octanol phase. Otherwise, it is trapped at the interface, attracted by water. These results are compared to those obtained with chloroform as organic phase and discussed in the context of synergistic effect of CCD(-) in liquid-liquid extraction, pointing to the importance of dual solvation properties of octanol and of the hydrophobic character of CCD(-) for synergistic extraction of cations.

  16. Sputtered catalysts

    International Nuclear Information System (INIS)

    Tyerman, W.J.R.

    1978-01-01

    A method is described for preparing a supported catalyst by a sputtering process. A material that is catalytic, or which is a component of a catalytic system, is sputtered on to the surface of refractory oxide particles that are compatible with the sputtered material and the sputtered particles are consolidated into aggregate form. The oxide particles before sputtering should have a diameter in the range 1000A to 50μ and a porosity less than 0.4 ml/g, and may comprise MgO, Al 2 O 3 or SiO 2 or mixtures of these oxides, including hydraulic cement. The particles may possess catalytic activity by themselves or in combination with the catalytic material deposited on them. Sputtering may be effected epitaxially and consolidation may be effected by compaction pelleting, extrusion or spray drying of a slurry. Examples of the use of such catalysts are given. (U.K.)

  17. Anions in Cometary Comae

    Science.gov (United States)

    Charnley, Steven B.

    2011-01-01

    The presence of negative ions (anions) in cometary comae is known from Giotto mass spectrometry of IP/Halley. The anions 0-, OH-, C-, CH- and CN- have been detected, as well as unidentified anions with masses 22-65 and 85-110 amu (Chaizy et al. 1991). Organic molecular anions are known to have a significant impact on the charge balance of interstellar clouds and circumstellar envelopes and have been shown to act as catalysts for the gas-phase synthesis of larger hydrocarbon molecules in the ISM, but their importance in cometary comae has not yet been explored. We present details of the first attempt to model the chemistry of anions in cometary comae. Based on the combined chemical and hydro dynamical model of Rodgers & Charnley (2002), we investigate the role of large carbon-chain anions in cometary coma chemistry. We calculate the effects of these anions on coma thermodynamics, charge balance and examine their impact on molecule formation.

  18. Matrix and substrate effects on the sputtering of a 2 kDa molecule: Insights from molecular dynamics

    International Nuclear Information System (INIS)

    Delcorte, A.; Arezki, B.; Garrison, B.J.

    2003-01-01

    In an effort towards a more accurate theoretical description of matrix and substrate effects in organic sputtering, we report on molecular dynamics simulations of the desorption induced by 500 eV Ar projectiles bombarding samples composed of polystyrene (PS) oligomers embedded in a trimethylbenzene matrix or cast on a silver substrate. The ejection of intact PS molecules, sometimes accompanied by matrix molecules/silver atoms, is observed in the first 10 ps following the impact. For the 'matrix' sample, the results indicate that the emission of large amounts of organic material is mostly vibrationally induced. Extended calculations show that matrix:analyte clusters decay after emission, liberating the analyte in flight. In the case of the 'substrate' sample, the emission is oftentimes the result of the concerted upward motion of several metal atoms underneath the molecule. Finally, the comparison between a matrix:analyte sample confined in a nanostructured silver crystal and a purely organic sample under identical bombardment conditions shows that the presence of the silver medium significantly enhances the desorption yields

  19. Strong-field Photoionization of Sputtered Neutral Molecules for Molecular Depth Profiling

    Science.gov (United States)

    Willingham, D; Brenes, D. A.; Wucher, A

    2009-01-01

    Molecular depth profiles of an organic thin film of guanine vapor deposited onto a Ag substrate are obtained using a 40 keV C60 cluster ion beam in conjunction with time-of-flight secondary ion mass spectrometric (ToF-SIMS) detection. Strong-field, femtosecond photoionization of intact guanine molecules is used to probe the neutral component of the profile for direct comparison with the secondary ion component. The ability to simultaneously acquire secondary ions and photoionized neutral molecules reveals new fundamental information about the factors that influence the properties of the depth profile. Results show that there is an increased ionization probability for protonated molecular ions within the first 10 nm due to the generation of free protons within the sample. Moreover, there is a 50% increase in fragment ion signal relative to steady state values 25 nm before reaching the guanine/Ag interface as a result of interfacial chemical damage accumulation. An altered layer thickness of 20 nm is observed as a consequence of ion beam induced chemical mixing. In general, we show that the neutral component of a molecular depth profile using the strong-field photoionization technique can be used to elucidate the effects of variations in ionization probability on the yield of molecular ions as well as to aid in obtaining accurate information about depth dependent chemical composition that cannot be extracted from TOF-SIMS data alone. PMID:20495665

  20. A Systematic Study of Molecular Interactions of Anionic Drugs with a Dimethylaminoethyl Methacrylate Copolymer Regarding Solubility Enhancement.

    Science.gov (United States)

    Saal, Wiebke; Ross, Alfred; Wyttenbach, Nicole; Alsenz, Jochem; Kuentz, Martin

    2017-04-03

    The methacrylate-copolymer Eudragit EPO (EPO) has raised interest in solubility enhancement of anionic drugs. Effects on aqueous drug solubility at rather low polymer concentrations are barely known despite their importance upon dissolution and dilution of oral dosage forms. We provide evidence for substantial enhancement (factor 4-230) of aqueous solubility of poorly water-soluble anionic drugs induced by low (0.1-5% (w/w)) concentration of EPO for a panel of seven acidic crystalline drugs. Diffusion data (determined by 1 H nuclear magnetic resonance spectroscopy) indicate that the solubility increasing effect monitored by quantitative ultraperformance liquid chromatography was caused primarily by molecular API polymer interactions in the bulk liquid phase. Residual solid API remained unaltered as tested by X-ray powder diffraction. The solubility enhancement (SE) revealed a significant rank correlation (r Spearman = -0.83) with rDiff API , where SE and rDiff API are defined ratios of solubility and diffusion coefficient in the presence and absence of EPO. SE decreased in the order of indomethacin, mefenamic acid, warfarin, piroxicam, furosemide, bezafibrate, and tolbutamide. The solubilizing effect was attributed to both ionic and hydrophobic interactions between drugs and EPO. The excellent solubilizing properties of EPO are highly promising for pharmaceutical development, and the data set provides first steps toward an understanding of drug-excipient interaction mechanisms.

  1. A combined experimental and computational study of the molecular interactions between anionic ibuprofen and water

    Energy Technology Data Exchange (ETDEWEB)

    Zapata-Escobar, Andy; Manrique-Moreno, Marcela; Guerra, Doris; Hadad, C. Z.; Restrepo, Albeiro, E-mail: albeiro@exactas.udea.edu.co [Instituto de Química, Universidad de Antioquia UdeA, Calle 70 No. 52–21, Medellín (Colombia)

    2014-05-14

    In this work, we report a detailed study of the microsolvation of anionic ibuprofen, Ibu{sup −}. Stochastic explorations of the configurational spaces for the interactions of Ibu{sup −} with up to three water molecules at the DFT level lead to very rich and complex potential energy surfaces. Our results suggest that instead of only one preponderant structure, a collection of isomers with very similar energies would have significant contributions to the properties of the solvated drug. One of these properties is the shift on the vibrational frequencies of the asymmetric stretching band of the carboxylate group in hydrated Ibu{sup −} with respect to the anhydrous drug, whose experimental values are nicely reproduced using the weighted contribution of the structures. We found at least three types of stabilizing interactions, including conventional CO {sub 2}{sup −}⋯H{sub 2}O, H{sub 2}O⋯H{sub 2}O charge assisted hydrogen bonds (HBs), and less common H{sub 2}O⋯H–C and H{sub 2}O⋯π interactions. Biological water molecules, those in direct contact with Ibu{sup −}, prefer to cluster around the carboxylate oxygen atoms via cyclic or bridged charge assisted hydrogen bonds. Many of those interactions are strongly affected by the formal carboxylate charge, resulting in “enhanced” HBs with increased strengths and degree of covalency. We found striking similarities between this case and the microsolvation of dymethylphosphate, which lead us to hypothesize that since microsolvation of phosphatidylcholine depends mainly on the formal charge of its ionic PO {sub 2}{sup −} group in the polar head, then microsolvation of anionic ibuprofen and interactions of water molecules with eukaryotic cell membranes are governed by the same types of physical interactions.

  2. A combined experimental and computational study of the molecular interactions between anionic ibuprofen and water

    International Nuclear Information System (INIS)

    Zapata-Escobar, Andy; Manrique-Moreno, Marcela; Guerra, Doris; Hadad, C. Z.; Restrepo, Albeiro

    2014-01-01

    In this work, we report a detailed study of the microsolvation of anionic ibuprofen, Ibu − . Stochastic explorations of the configurational spaces for the interactions of Ibu − with up to three water molecules at the DFT level lead to very rich and complex potential energy surfaces. Our results suggest that instead of only one preponderant structure, a collection of isomers with very similar energies would have significant contributions to the properties of the solvated drug. One of these properties is the shift on the vibrational frequencies of the asymmetric stretching band of the carboxylate group in hydrated Ibu − with respect to the anhydrous drug, whose experimental values are nicely reproduced using the weighted contribution of the structures. We found at least three types of stabilizing interactions, including conventional CO 2 − ⋯H 2 O, H 2 O⋯H 2 O charge assisted hydrogen bonds (HBs), and less common H 2 O⋯H–C and H 2 O⋯π interactions. Biological water molecules, those in direct contact with Ibu − , prefer to cluster around the carboxylate oxygen atoms via cyclic or bridged charge assisted hydrogen bonds. Many of those interactions are strongly affected by the formal carboxylate charge, resulting in “enhanced” HBs with increased strengths and degree of covalency. We found striking similarities between this case and the microsolvation of dymethylphosphate, which lead us to hypothesize that since microsolvation of phosphatidylcholine depends mainly on the formal charge of its ionic PO 2 − group in the polar head, then microsolvation of anionic ibuprofen and interactions of water molecules with eukaryotic cell membranes are governed by the same types of physical interactions

  3. Sputtering of a silicon surface: Preferential sputtering of surface impurities

    Czech Academy of Sciences Publication Activity Database

    Nietiadi, M.L.; Rosandi, Y.; Lorinčík, Jan; Urbassek, H.M.

    -, č. 303 (2013), s. 205-208 ISSN 0168-583X Institutional support: RVO:67985882 Keywords : Sputtering * Molecular dynamics * SIMS Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.186, year: 2013

  4. Mg-Al layered double hydroxide intercalated with porphyrin anions: molecular simulations and experiments

    Czech Academy of Sciences Publication Activity Database

    Kovář, P.; Pospíšil, M.; Káfuňková, Eva; Lang, Kamil; Kovanda, F.

    2010-01-01

    Roč. 16, č. 2 (2010), s. 223-233 ISSN 1610-2940 R&D Projects: GA ČR(CZ) GA203/06/1244; GA AV ČR KAN100500651 Institutional research plan: CEZ:AV0Z40320502 Keywords : layered double hydroxide * porphyrin * molecular simulations Subject RIV: CA - Inorganic Chemistry Impact factor: 1.871, year: 2010

  5. The potential of flow-through microdialysis for probing low-molecular weight organic anions in rhizosphere soil solution.

    Science.gov (United States)

    Sulyok, Michael; Miró, Manuel; Stingeder, Gerhard; Koellensperger, Gunda

    2005-08-01

    In this paper, flow-through microdialysis is presented as a novel analytical tool for automatic sampling of low molecular weight organic anions (LMWOA), such as oxalate and citrate, in solid samples of environmental concern. The microsampling methodology involves the implantation of dedicated capillary-type probes offering unrivalled spatial resolution (ca. 200μm) in definite soil sites. These passive samplers are aimed at monitoring local processes, such as the release of organic acids occurring in the rhizosphere environment, in nearly real-time. The influence of chemical and physical variables (composition and flow rate of the perfusion liquid, ionic strength and pH of the outer medium and presence of metal ions therein) was assessed in vitro using liquid-phase assays. On the other hand, the resistance of the external solid medium to mass transfer, and the actual applicability of in vivo calibration methods were investigated using quartz sand as an inert model soil. Microdialysers furnished with 3cm long semipermeable tubular membranes were perfused with 0.01M NaNO 3 at a flow rate of 2.0μl/min, yielding dialysis recoveries ≥45% for both assayed LMWOAs in simulated background soil electrolyte solutions, and ≥24% in the interstitial liquid of complex solid samples. Full knowledge of the fate of LMWOAs in soils was obtained through the application of stimulus-response approaches that mimic the discrete exudation pulses of roots. Highly time-resolved microdialysates were used to discern readily available species such as free carboxylic anions and LMW metal-organic acid complexes from adsorbed, precipitated or mineralised analyte species in a variety of soil samples containing variable amounts of organic matter, exchangeable cations and different levels of metal pollution.

  6. Mixtures of nonionic and anionic surfactants: interactions with low-molecular-mass homopeptides

    Czech Academy of Sciences Publication Activity Database

    Forgács, E.; Cserháti, T.; Deyl, Zdeněk; Mikšík, Ivan; Eckhardt, Adam

    2001-01-01

    Roč. 917, 1-2 (2001), s. 287-295 ISSN 0021-9673 R&D Projects: GA ČR GV203/96/K128; GA ČR GA203/99/0191; GA ČR GA203/00/D032 Institutional research plan: CEZ:AV0Z5011922 Keywords : molecular interactions * regression analysis * surfactants Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.793, year: 2001

  7. Surface Solvation of Halogen Anions in Water Clusters: An ab initio Molecular Dynamics Study of the Cl-(H.sub.2./sub.O).sub.6./sub. Complex

    Czech Academy of Sciences Publication Activity Database

    Tobias, D. J.; Jungwirth, Pavel; Parrinello, M.

    2001-01-01

    Roč. 114, č. 16 (2001), s. 7036-7044 ISSN 0021-9606 R&D Projects: GA MŠk LN00A032 Grant - others:NATO Science Program(XE) CLG-974459 Institutional research plan: CEZ:AV0Z4040901 Keywords : cluster * ab initio molecular dynamics * anionic solvation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.147, year: 2001

  8. Colorless to purple-red switching electrochromic anthraquinone imides with broad visible/near-IR absorptions in the radical anion state: simulation-aided molecular design.

    Science.gov (United States)

    Chen, Fengkun; Zhang, Jie; Jiang, Hong; Wan, Xinhua

    2013-07-01

    The large redshift of near-infrared (NIR) absorptions of nitro-substituted anthraquinone imide (Nitro-AQI) radical anions, relative to other AQI derivatives, is rationalized based on quantum chemical calculations. Calculations reveal that the delocalization effects of electronegative substitution in the radical anion states is dramatically enhanced, thus leading to a significant decrease in the HOMO-LUMO band gap in the radical anion states. Based on this understanding, an AQI derivative with an even stronger electron-withdrawing dicyanovinyl (di-CN) substituent was designed and prepared. The resulting molecule, di-CN-AQI, displays no absorption in the Vis/NIR region in the neutral state, but absorbs intensively in the range of λ=700-1000 (λmax ≈860 nm) and λ=1100-1800 nm (λmax ≈1400 nm) upon one-electron reduction; this is accompanied by a transition from a highly transmissive colorless solution to one that is purple-red. The relationship between calculated radical anionic HOMO-LUMO gaps and the electron-withdrawing capacity of the substituents is also determined by employing Hammett parameter, which could serve as a theoretical tool for further molecular design. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. The Influence of Anion Shape on the Electrical Double Layer Microstructure and Capacitance of Ionic Liquids-Based Supercapacitors by Molecular Simulations

    Directory of Open Access Journals (Sweden)

    Ming Chen

    2017-02-01

    Full Text Available Room-temperature ionic liquids (RTILs are an emerging class of electrolytes for supercapacitors. In this work, we investigate the effects of different supercapacitor models and anion shape on the electrical double layers (EDLs of two different RTILs: 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonylimide ([Emim][Tf2N] and 1-ethyl-3-methylimidazolium 2-(cyanopyrrolide ([Emim][CNPyr] by molecular dynamics (MD simulation. The EDL microstructure is represented by number densities of cations and anions, and the potential drop near neutral and charged electrodes reveal that the supercapacitor model with a single electrode has the same EDL structure as the model with two opposite electrodes. Nevertheless, the employment of the one-electrode model without tuning the bulk density of RTILs is more time-saving in contrast to the two-electrode one. With the one-electrode model, our simulation demonstrated that the shapes of anions significantly imposed effects on the microstructure of EDLs. The EDL differential capacitance vs. potential (C-V curves of [Emim][CNPyr] electrolyte exhibit higher differential capacitance at positive potentials. The modeling study provides microscopic insight into the EDLs structure of RTILs with different anion shapes.

  10. Evidence for radical anion formation during liquid secondary ion mass spectrometry analysis of oligonucleotides and synthetic oligomeric analogues: a deconvolution algorithm for molecular ion region clusters.

    Science.gov (United States)

    Laramée, J A; Arbogast, B; Deinzer, M L

    1989-10-01

    It is shown that one-electron reduction is a common process that occurs in negative ion liquid secondary ion mass spectrometry (LSIMS) of oligonucleotides and synthetic oligonucleosides and that this process is in competition with proton loss. Deconvolution of the molecular anion cluster reveals contributions from (M-2H).-, (M-H)-, M.-, and (M + H)-. A model based on these ionic species gives excellent agreement with the experimental data. A correlation between the concentration of species arising via one-electron reduction [M.- and (M + H)-] and the electron affinity of the matrix has been demonstrated. The relative intensity of M.- is mass-dependent; this is rationalized on the basis of base-stacking. Base sequence ion formation is theorized to arise from M.- radical anion among other possible pathways.

  11. Novel ion-molecular surface reaction to result in CH3 adsorbates on (111) surface of chemical vapor deposition diamond from ethane and surface anionic sites

    International Nuclear Information System (INIS)

    Komatsu, Shojiro; Okada, Katsuyuki; Shimizu, Yoshiki; Moriyoshi, Yusuke

    2001-01-01

    The existence of CH 3 adsorbates on (111) surface of chemical vapor deposited diamond, which was observed by scanning tunneling microscopy, was explained by the following S N 2 (bimolecular, substitutional, and nucleophilic) type surface reaction; C(s) - +C 2 H 6 ->C(s)-CH 3 +CH 3 - , where C(s) denotes a surface carbon atom. The activation energy was estimated to be 36.78 kcal/mol and the reaction proved to be exothermic with the enthalpy change of -9.250 kcal/mol, according to ab initio molecular orbital calculations at MP2/3-21+G * //RHF/3-21G * level; this result is consistent with typical substrate temperatures, namely about 900 degree C, for chemical vapor deposition of diamond. Charge transfer from the highest occupied molecular orbital of the surface anionic site to the lowest unoccupied molecular orbital of ethane, that is antibonding at the CH 3 - CH 3 bond, has been clearly visualized. A characteristic configuration of an ethane molecule which is associated with an anionic vacant site C(s) - on hydrogenated (111) surface of diamond was also found. [copyright] 2001 American Institute of Physics

  12. Halide anion solvation and recognition by a macro tri-cyclic tetra-ammonium host in an ionic liquid: a molecular dynamics stud

    International Nuclear Information System (INIS)

    Chaumont, A.; Wipff, G.

    2006-01-01

    We report a molecular dynamics study of halide anions X - and their inclusion complexes X - - L 4+ with a macro-tri-cyclic tetrahedral host L 4+ built from four quaternary ammonium sites, in an ionic liquid (IL) based on the 1-butyl-3-methyl-imidazolium (BMI + ) cation and the PF 6 - anion. The 'dry' and 'humid' forms of the [BMI][PF 6 ] IL are compared, showing the importance of IL ions in the 'dry' IL and, in some cases, of water molecules in the 'humid' IL. In the 'dry' IL the F - , Cl - , Br - and I - un-complexed halides are surrounded by 4-5 BMI + cations whose binding mode evolves from hydrogen bonding to facial coordination along this series. Solvent humidity has the largest impact on the solvation of F - whose first shell BMI + cations are all displaced by H 2 O molecules, while the first solvation shell of Cl - , Br - and I - comprises 3-4 BMI + cations plus ca. 4 H 2 O molecules. The solvation of the L 4+ host and of its X - - L 4+ complex mainly involves PF 6 - anions in the 'dry' IL, and additional H 2 O molecules in the 'humid' IL. The question of anion binding selectivity is addressed by free energy perturbation calculations which predict that, in the 'dry' liquid, F - is preferred over Cl - , Br - and I - , which contrasts with the aqueous solution where L 4+ is selective for Cl - . In the 'humid' liquid however, there is no F - /Cl - discrimination, showing the importance of small amounts of water on the complexation selectivity. (authors)

  13. Physiological and Molecular Analysis of Aluminium-Induced Organic Acid Anion Secretion from Grain Amaranth (Amaranthus hypochondriacus L.) Roots

    OpenAIRE

    Fan, Wei; Xu, Jia-Meng; Lou, He-Qiang; Xiao, Chuan; Chen, Wei-Wei; Yang, Jian-Li

    2016-01-01

    Grain amaranth (Amaranthus hypochondriacus L.) is abundant in oxalate and can secrete oxalate under aluminium (Al) stress. However, the features of Al-induced secretion of organic acid anions (OA) and potential genes responsible for OA secretion are poorly understood. Here, Al-induced OA secretion in grain amaranth roots was characterized by ion charomatography and enzymology methods, and suppression subtractive hybridization (SSH) together with quantitative real-time PCR (qRT-PCR) was used t...

  14. Isotope puzzle in sputtering

    International Nuclear Information System (INIS)

    Zheng Liping

    1998-01-01

    Mechanisms affecting multicomponent material sputtering are complex. Isotope sputtering is the simplest in the multicomponent materials sputtering. Although only mass effect plays a dominant role in the isotope sputtering, there is still an isotope puzzle in sputtering by ion bombardment. The major arguments are as follows: (1) At the zero fluence, is the isotope enrichment ejection-angle-independent or ejection-angle-dependent? (2) Is the isotope angular effect the primary or the secondary sputter effect? (3) How to understand the action of momentum asymmetry in collision cascade on the isotope sputtering?

  15. A fluorescent molecular sensor for pH windows in traditional and polymeric biocompatible micelles: comicellization of anionic species to shift and reshape the ON window.

    Science.gov (United States)

    Cavallaro, Gennara; Giammona, Gaetano; Pasotti, Luca; Pallavicini, Piersandro

    2011-09-12

    A new approach is presented to obtain fluorescent sensors for pH windows that work in water and under biomimetic conditions. A single molecule that features all-covalently linked components is used, thus making it capable of working as a fluorescent sensor with an OFF/ON/OFF response to pH value. The components are a tertiary amine, a pyridine, and a fluorophore (pyrene). The forms with both protonated bases or both neutral bases quench the pyrene fluorescence, whereas the form with the neutral pyridine and protonated amine groups is fluorescent. The molecular sensor is also equipped with a long alkyl chain to make it highly hydrophobic in all its protonated and unprotonated forms, that is, either when neutral or charged. Accordingly, it can be confined at any pH value either in traditional (i.e., low-molecular-weight) nonionic surfactant micelles or inside polymeric, biocompatible micellar containers. Relevant for future applications in vivo, thanks to its strong hydrophobicity, no leakage of the molecular sensor is observed from the polymeric biocompatible micelles. Due to the proximity of the pyridine and amine functions in the molecular structure and the poor hydration inside the micelles, the observed pK(a) values are low so that the ON window is positioned at very low pH values. However, the window can be shifted to biologically relevant values by comicellization of anionic species. In particular, in the micelles of the nonionic surfactant TritonX-100, a shift of the ON window to pH 4-6 is obtained by addition of the anionic sodium dodecyl sulphate surfactant, whose negative charge promotes the stability of the protonated forms of the pyridine and amine fragments. In the case of the polymeric micelles, we introduce the use of the amphiphilic polystyrene sulfonate anionic polyelectrolyte, the comicellization of which induces a shift and sharpening of the ON window that is centered at pH 4. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Evolution of Voltage-Dependent Anion Channel Function: From Molecular Sieve to Governator to Actuator of Ferroptosis

    Directory of Open Access Journals (Sweden)

    John J. Lemasters

    2017-12-01

    Full Text Available The voltage-dependent anion channel (VDAC is well known as the pathway for passive diffusion of anionic hydrophilic mitochondrial metabolites across the outer membrane, but a more complex functionality of the three isoforms of VDAC has emerged, as addressed in the Frontiers in Oncology Research Topic on “Uncovering the Function of the Mitochondrial Protein VDAC in Health and Disease: from Structure-Function to Novel Therapeutic Strategies.” VDAC as the single most abundant protein in mitochondrial outer membranes is typically involved in isoform-specific interactions of the mitochondrion with its surroundings as, for example, during mitochondria-dependent pathways of cell death. VDAC closure can also act as an adjustable limiter (governator of global mitochondrial metabolism, as during hepatic ethanol metabolism to promote selective oxidation of membrane-permeant acetaldehyde. In cancer cells, high free tubulin inhibits VDAC1 and VDAC2, contributing to suppression of mitochondrial function in the Warburg phenomenon. Erastin, the canonical inducer of ferroptosis, opens VDAC in the presence of tubulin and hyperpolarizes mitochondria, leading to mitochondrial production of reactive oxygen species, mitochondrial dysfunction, and cell death. Our understanding of VDAC function continues to evolve.

  17. Towards a molecular understanding of cellulose dissolution in ionic liquids: anion/cation effect, synergistic mechanism and physicochemical aspects.

    Science.gov (United States)

    Li, Yao; Wang, Jianji; Liu, Xiaomin; Zhang, Suojiang

    2018-05-07

    Cellulose is one of the most abundant bio-renewable materials on the earth and its conversion to biofuels provides an appealing way to satisfy the increasing global energy demand. However, before carrying out the process of enzymolysis to glucose or polysaccharides, cellulose needs to be pretreated to overcome its recalcitrance. In recent years, a variety of ionic liquids (ILs) have been found to be effective solvents for cellulose, providing a new, feasible pretreatment strategy. A lot of experimental and computational studies have been carried out to investigate the dissolution mechanism. However, many details are not fully understood, which highlights the necessity to overview the current knowledge of cellulose dissolution and identify the research trend in the future. This perspective summarizes the mechanistic studies and microscopic insights of cellulose dissolution in ILs. Recent investigations of the synergistic effect of cations/anions and the distinctive structural changes of cellulose microfibril in ILs are also reviewed. Besides, understanding the factors controlling the dissolution process, such as the structure of anions/cations, viscosity of ILs, pretreatment temperature, heating rate, etc. , has been discussed from a structural and physicochemical viewpoint. At the end, the existing problems are discussed and future prospects are given. We hope this article would be helpful for deeper understanding of the cellulose dissolution process in ILs and the rational design of more efficient and recyclable ILs.

  18. Organic solvent and temperature-enhanced ion chromatography-high resolution mass spectrometry for the determination of low molecular weight organic and inorganic anions

    International Nuclear Information System (INIS)

    Gilchrist, Elizabeth S.; Nesterenko, Pavel N.; Smith, Norman W.; Barron, Leon P.

    2015-01-01

    Highlights: • IC selectivity at high contents of organic solvent in eluent and elevated temperature is studied. • Solvent-enhanced IC coupled to high resolution MS is beneficial for sensitive detection of ions. • The first application of IC-HRMS to the detection of low explosives in fingermarks is shown. - Abstract: There has recently been increased interest in coupling ion chromatography (IC) to high resolution mass spectrometry (HRMS) to enable highly sensitive and selective analysis. Herein, the first comprehensive study focusing on the direct coupling of suppressed IC to HRMS without the need for post-suppressor organic solvent modification is presented. Chromatographic selectivity and added HRMS sensitivity offered by organic solvent-modified IC eluents on a modern hyper-crosslinked polymeric anion-exchange resin (IonPac AS18) are shown using isocratic eluents containing 5–50 mM hydroxide with 0–80% methanol or acetonitrile for a range of low molecular weight anions (<165 Da). Comprehensive experiments on IC thermodynamics over a temperature range between 20–45 °C with the eluent containing up to 60% of acetonitrile or methanol revealed markedly different retention behaviour and selectivity for the selected analytes on the same polymer based ion-exchange resin. Optimised sensitivity with HRMS was achieved with as low as 30–40% organic eluent content. Analytical performance characteristics are presented and compared with other IC-MS based works. This study also presents the first application of IC-HRMS to forensic detection of trace low-order anionic explosive residues in latent human fingermarks

  19. Organic solvent and temperature-enhanced ion chromatography-high resolution mass spectrometry for the determination of low molecular weight organic and inorganic anions

    Energy Technology Data Exchange (ETDEWEB)

    Gilchrist, Elizabeth S. [Analytical & Environmental Science Division, Department of Forensic & Analytical Science, King’s College London, 150 Stamford Street, London, SE1 9NH (United Kingdom); Nesterenko, Pavel N. [Australian Centre for Research on Separation Science, School of Physical Sciences, University of Tasmania, Private Bag 75, Hobart 7001 (Australia); Smith, Norman W. [Analytical & Environmental Science Division, Department of Forensic & Analytical Science, King’s College London, 150 Stamford Street, London, SE1 9NH (United Kingdom); Barron, Leon P., E-mail: leon.barron@kcl.ac.uk [Analytical & Environmental Science Division, Department of Forensic & Analytical Science, King’s College London, 150 Stamford Street, London, SE1 9NH (United Kingdom)

    2015-03-20

    Highlights: • IC selectivity at high contents of organic solvent in eluent and elevated temperature is studied. • Solvent-enhanced IC coupled to high resolution MS is beneficial for sensitive detection of ions. • The first application of IC-HRMS to the detection of low explosives in fingermarks is shown. - Abstract: There has recently been increased interest in coupling ion chromatography (IC) to high resolution mass spectrometry (HRMS) to enable highly sensitive and selective analysis. Herein, the first comprehensive study focusing on the direct coupling of suppressed IC to HRMS without the need for post-suppressor organic solvent modification is presented. Chromatographic selectivity and added HRMS sensitivity offered by organic solvent-modified IC eluents on a modern hyper-crosslinked polymeric anion-exchange resin (IonPac AS18) are shown using isocratic eluents containing 5–50 mM hydroxide with 0–80% methanol or acetonitrile for a range of low molecular weight anions (<165 Da). Comprehensive experiments on IC thermodynamics over a temperature range between 20–45 °C with the eluent containing up to 60% of acetonitrile or methanol revealed markedly different retention behaviour and selectivity for the selected analytes on the same polymer based ion-exchange resin. Optimised sensitivity with HRMS was achieved with as low as 30–40% organic eluent content. Analytical performance characteristics are presented and compared with other IC-MS based works. This study also presents the first application of IC-HRMS to forensic detection of trace low-order anionic explosive residues in latent human fingermarks.

  20. Ion-induced sputtering

    International Nuclear Information System (INIS)

    Yamamura, Yasumichi; Shimizu, Ryuichi; Shimizu, Hazime; Ito, Noriaki.

    1983-01-01

    The research on ion-induced sputtering has been continued for a long time, since a hundred or more years ago. However, it was only in 1969 by Sigmund that the sputtering phenomena were theoretically arranged into the present form. The reason why the importance of sputtering phenomena have been given a new look recently is the application over wide range. This paper is a review centering around the mechanism of causing sputtering and its characteristics. Sputtering is such a phenomenon that the atoms in the vicinity of a solid surface are emitted into vacuum by receiving a part of ion energy, or in other words, it is a kind of irradiation damage in the vicinity of a solid surface. In this meaning, it can be considered that the sputtering based on the ions located on the clean surface of a single element metal is simple, and has already been basically understood. On the contrary, the phenomena can not be considered to be fully understood in the case of alloys and compounds, because these surface conditions under irradiation are not always clear due to segregation and others. In the paper, the physical of sputtering, single element sputtering, the sputtering in alloys and compounds, and the behaviour of emitted particles are explained. Finally, some recent topics of the sputtering measurement by laser resonant excitation, the sputtering by electron excitation, chemical sputtering, and the sputtering in nuclear fusion reactors are described. (Wakatsuki, Y.)

  1. Molecular rheology of branched polymers: decoding and exploring the role of architectural dispersity through a synergy of anionic synthesis, interaction chromatography, rheometry and modeling.

    Science.gov (United States)

    van Ruymbeke, E; Lee, H; Chang, T; Nikopoulou, A; Hadjichristidis, N; Snijkers, F; Vlassopoulos, D

    2014-07-21

    An emerging challenge in polymer physics is the quantitative understanding of the influence of a macromolecular architecture (i.e., branching) on the rheological response of entangled complex polymers. Recent investigations of the rheology of well-defined architecturally complex polymers have determined the composition in the molecular structure and identified the role of side-products in the measured samples. The combination of different characterization techniques, experimental and/or theoretical, represents the current state-of-the-art. Here we review this interdisciplinary approach to molecular rheology of complex polymers, and show the importance of confronting these different tools for ensuring an accurate characterization of a given polymeric sample. We use statistical tools in order to relate the information available from the synthesis protocols of a sample and its experimental molar mass distribution (typically obtained from size exclusion chromatography), and hence obtain precise information about its structural composition, i.e. enhance the existing sensitivity limit. We critically discuss the use of linear rheology as a reliable quantitative characterization tool, along with the recently developed temperature gradient interaction chromatography. The latter, which has emerged as an indispensable characterization tool for branched architectures, offers unprecedented sensitivity in detecting the presence of different molecular structures in a sample. Combining these techniques is imperative in order to quantify the molecular composition of a polymer and its consequences on the macroscopic properties. We validate this approach by means of a new model asymmetric comb polymer which was synthesized anionically. It was thoroughly characterized and its rheology was carefully analyzed. The main result is that the rheological signal reveals fine molecular details, which must be taken into account to fully elucidate the viscoelastic response of entangled branched

  2. Molecular rheology of branched polymers: Decoding and exploring the role of architectural dispersity through a synergy of anionic synthesis, interaction chromatography, rheometry and modeling

    KAUST Repository

    Van Ruymbeke, Evelyne

    2014-01-01

    An emerging challenge in polymer physics is the quantitative understanding of the influence of a macromolecular architecture (i.e., branching) on the rheological response of entangled complex polymers. Recent investigations of the rheology of well-defined architecturally complex polymers have determined the composition in the molecular structure and identified the role of side-products in the measured samples. The combination of different characterization techniques, experimental and/or theoretical, represents the current state-of-the-art. Here we review this interdisciplinary approach to molecular rheology of complex polymers, and show the importance of confronting these different tools for ensuring an accurate characterization of a given polymeric sample. We use statistical tools in order to relate the information available from the synthesis protocols of a sample and its experimental molar mass distribution (typically obtained from size exclusion chromatography), and hence obtain precise information about its structural composition, i.e. enhance the existing sensitivity limit. We critically discuss the use of linear rheology as a reliable quantitative characterization tool, along with the recently developed temperature gradient interaction chromatography. The latter, which has emerged as an indispensable characterization tool for branched architectures, offers unprecedented sensitivity in detecting the presence of different molecular structures in a sample. Combining these techniques is imperative in order to quantify the molecular composition of a polymer and its consequences on the macroscopic properties. We validate this approach by means of a new model asymmetric comb polymer which was synthesized anionically. It was thoroughly characterized and its rheology was carefully analyzed. The main result is that the rheological signal reveals fine molecular details, which must be taken into account to fully elucidate the viscoelastic response of entangled branched

  3. Variables affecting simulated Be sputtering yields

    Energy Technology Data Exchange (ETDEWEB)

    Björkas, C., E-mail: carolina.bjorkas@helsinki.fi; Nordlund, K.

    2013-08-15

    Since beryllium is a strong candidate for the main plasma-facing material in future fusion reactors, its sputtering behaviour plays an important role in predicting the reactor’s life-time. Consensus about the actual sputtering yields has not yet been achieved, as observations are influenced by experimental method and/or studied sample. In this work, the beryllium sputtering due to deuterium and beryllium self-bombardment is analyzed using molecular dynamics simulations. The main methodological aspects that influence the outcome, such as flux and fluence of the bombardment, are highlighted, and it is shown that the simulated yields also depend on the sample structure and deuterium content.

  4. Sputtering of water ice

    International Nuclear Information System (INIS)

    Baragiola, R.A.; Vidal, R.A.; Svendsen, W.; Schou, J.; Shi, M.; Bahr, D.A.; Atteberrry, C.L.

    2003-01-01

    We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from the decay of H(2p) atoms sputtered by heavy ion impact, but not bulk ice luminescence. Radiolyzed ice does not sputter under 3.7 eV laser irradiation

  5. Physiological and Molecular Analysis of Aluminium-Induced Organic Acid Anion Secretion from Grain Amaranth (Amaranthus hypochondriacus L.) Roots

    Science.gov (United States)

    Fan, Wei; Xu, Jia-Meng; Lou, He-Qiang; Xiao, Chuan; Chen, Wei-Wei; Yang, Jian-Li

    2016-01-01

    Grain amaranth (Amaranthus hypochondriacus L.) is abundant in oxalate and can secrete oxalate under aluminium (Al) stress. However, the features of Al-induced secretion of organic acid anions (OA) and potential genes responsible for OA secretion are poorly understood. Here, Al-induced OA secretion in grain amaranth roots was characterized by ion charomatography and enzymology methods, and suppression subtractive hybridization (SSH) together with quantitative real-time PCR (qRT-PCR) was used to identify up-regulated genes that are potentially involved in OA secretion. The results showed that grain amaranth roots secrete both oxalate and citrate in response to Al stress. The secretion pattern, however, differs between oxalate and citrate. Neither lanthanum chloride (La) nor cadmium chloride (Cd) induced OA secretion. A total of 84 genes were identified as up-regulated by Al, in which six genes were considered as being potentially involved in OA secretion. The expression pattern of a gene belonging to multidrug and toxic compound extrusion (MATE) family, AhMATE1, was in close agreement with that of citrate secretion. The expression of a gene encoding tonoplast dicarboxylate transporter and four genes encoding ATP-binding cassette transporters was differentially regulated by Al stress, but the expression pattern was not correlated well with that of oxalate secretion. Our results not only reveal the secretion pattern of oxalate and citrate from grain amaranth roots under Al stress, but also provide some genetic information that will be useful for further characterization of genes involved in Al toxicity and tolerance mechanisms. PMID:27144562

  6. Physiological and Molecular Analysis of Aluminium-Induced Organic Acid Anion Secretion from Grain Amaranth (Amaranthus hypochondriacus L.) Roots.

    Science.gov (United States)

    Fan, Wei; Xu, Jia-Meng; Lou, He-Qiang; Xiao, Chuan; Chen, Wei-Wei; Yang, Jian-Li

    2016-04-30

    Grain amaranth (Amaranthus hypochondriacus L.) is abundant in oxalate and can secrete oxalate under aluminium (Al) stress. However, the features of Al-induced secretion of organic acid anions (OA) and potential genes responsible for OA secretion are poorly understood. Here, Al-induced OA secretion in grain amaranth roots was characterized by ion charomatography and enzymology methods, and suppression subtractive hybridization (SSH) together with quantitative real-time PCR (qRT-PCR) was used to identify up-regulated genes that are potentially involved in OA secretion. The results showed that grain amaranth roots secrete both oxalate and citrate in response to Al stress. The secretion pattern, however, differs between oxalate and citrate. Neither lanthanum chloride (La) nor cadmium chloride (Cd) induced OA secretion. A total of 84 genes were identified as up-regulated by Al, in which six genes were considered as being potentially involved in OA secretion. The expression pattern of a gene belonging to multidrug and toxic compound extrusion (MATE) family, AhMATE1, was in close agreement with that of citrate secretion. The expression of a gene encoding tonoplast dicarboxylate transporter and four genes encoding ATP-binding cassette transporters was differentially regulated by Al stress, but the expression pattern was not correlated well with that of oxalate secretion. Our results not only reveal the secretion pattern of oxalate and citrate from grain amaranth roots under Al stress, but also provide some genetic information that will be useful for further characterization of genes involved in Al toxicity and tolerance mechanisms.

  7. Physiological and Molecular Analysis of Aluminium-Induced Organic Acid Anion Secretion from Grain Amaranth (Amaranthus hypochondriacus L. Roots

    Directory of Open Access Journals (Sweden)

    Wei Fan

    2016-04-01

    Full Text Available Grain amaranth (Amaranthus hypochondriacus L. is abundant in oxalate and can secrete oxalate under aluminium (Al stress. However, the features of Al-induced secretion of organic acid anions (OA and potential genes responsible for OA secretion are poorly understood. Here, Al-induced OA secretion in grain amaranth roots was characterized by ion charomatography and enzymology methods, and suppression subtractive hybridization (SSH together with quantitative real-time PCR (qRT-PCR was used to identify up-regulated genes that are potentially involved in OA secretion. The results showed that grain amaranth roots secrete both oxalate and citrate in response to Al stress. The secretion pattern, however, differs between oxalate and citrate. Neither lanthanum chloride (La nor cadmium chloride (Cd induced OA secretion. A total of 84 genes were identified as up-regulated by Al, in which six genes were considered as being potentially involved in OA secretion. The expression pattern of a gene belonging to multidrug and toxic compound extrusion (MATE family, AhMATE1, was in close agreement with that of citrate secretion. The expression of a gene encoding tonoplast dicarboxylate transporter and four genes encoding ATP-binding cassette transporters was differentially regulated by Al stress, but the expression pattern was not correlated well with that of oxalate secretion. Our results not only reveal the secretion pattern of oxalate and citrate from grain amaranth roots under Al stress, but also provide some genetic information that will be useful for further characterization of genes involved in Al toxicity and tolerance mechanisms.

  8. Liquid Structure of CO 2 –Reactive Aprotic Heterocyclic Anion Ionic Liquids from X-ray Scattering and Molecular Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sheridan, Quintin R.; Oh, Seungmin; Morales-Collazo, Oscar; Castner, Jr., Edward W.; Brennecke, Joan F.; Maginn, Edward J. (Rutgers); (Notre)

    2016-11-23

    A combination of X-ray scattering experiments and molecular dynamics simulations were conducted to investigate the structure of ionic liquids (ILs) which chemically bind CO2. The structure functions were measured and computed for four different ILs consisting of two different phosphonium cations, triethyloctylphosphonium ([P2228]+) and trihexyltetradecylphosphonium ([P66614]+), paired with two different aprotic heterocyclic anions which chemically react with CO2, 2-cyanopyrrolide, and 1,2,4-triazolide. Simulations were able to reproduce the experimental structure functions, and by deconstructing the simulated structure functions, further information on the liquid structure was obtained. All structure functions of the ILs studied had three primary features which have been seen before in other ILs: a prepeak near 0.3–0.4 Å–1 corresponding to polar/nonpolar domain alternation, a charge alternation peak near 0.8 Å–1, and a peak near 1.5 Å–1 due to interactions of adjacent molecules. The liquid structure functions were only mildly sensitive to the specific anion and whether or not they were reacted with CO2. Upon reacting with CO2, small changes were observed in the structure functions of the [P2228]+ ILs, whereas virtually no change was observed upon reacting with CO2 in the corresponding [P66614]+ ILs. When the [P2228]+ cation was replaced with the [P66614]+ cation, there was a significant increase in the intensities of the prepeak and adjacency interaction peak. While many of the liquid structure functions are similar, the actual liquid structures differ as demonstrated by computed spatial distribution functions.

  9. Molecular structure investigation of neutral, dimer and anion forms of 3,4-pyridinedicarboxylic acid: a combined experimental and theoretical study.

    Science.gov (United States)

    Karabacak, Mehmet; Bilgili, Sibel; Atac, Ahmet

    2015-01-25

    In this study, the structural and vibrational analysis of 3,4-pyridinedicarboxylic acid (3,4-PDCA) are presented using experimental techniques as FT-IR, FT-Raman, NMR, UV and quantum chemical calculations. FT-IR and FT-Raman spectra of 3,4-pyridinedicarboxylic acid in the solid phase are recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1), respectively. The geometrical parameters and energies of all different and possible monomer, dimer, anion(-1) and anion(-2) conformers of 3,4-PDCA are obtained from Density Functional Theory (DFT) with B3LYP/6-311++G(d,p) basis set. There are sixteen conformers (C1C16) for this molecule (neutral form). The most stable conformer of 3,4-PDCA is the C1 conformer. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes calculated with scaled quantum mechanics (SQM) method. (1)H and (13)C NMR spectra are recorded and the chemical shifts are calculated by using DFT/B3LYP methods with 6-311++G(d,p) basis set. The UV absorption spectrum of the studied compound is recorded in the range of 200-400 nm by dissolved in ethanol. The optimized geometric parameters were compared with experimental data via the X-ray results derived from complexes of this molecule. In addition these, molecular electrostatic potential (MEP), thermodynamic and electronic properties, HOMO-LUMO energies and Mulliken atomic charges, are performed. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Molecular dynamics simulation, ab initio calculation, and size-selected anion photoelectron spectroscopy study of initial hydration processes of calcium chloride.

    Science.gov (United States)

    He, Zhili; Feng, Gang; Yang, Bin; Yang, Lijiang; Liu, Cheng-Wen; Xu, Hong-Guang; Xu, Xi-Ling; Zheng, Wei-Jun; Gao, Yi Qin

    2018-06-14

    To understand the initial hydration processes of CaCl 2 , we performed molecular simulations employing the force field based on the theory of electronic continuum correction with rescaling. Integrated tempering sampling molecular dynamics were combined with ab initio calculations to overcome the sampling challenge in cluster structure search and refinement. The calculated vertical detachment energies of CaCl 2 (H 2 O) n - (n = 0-8) were compared with the values obtained from photoelectron spectra, and consistency was found between the experiment and computation. Separation of the Cl-Ca ion pair is investigated in CaCl 2 (H 2 O) n - anions, where the first Ca-Cl ionic bond required 4 water molecules, and both Ca-Cl bonds are broken when the number of water molecules is larger than 7. For neutral CaCl 2 (H 2 O) n clusters, breaking of the first Ca-Cl bond starts at n = 5, and 8 water molecules are not enough to separate the two ion pairs. Comparing with the observations on magnesium chloride, it shows that separating one ion pair in CaCl 2 (H 2 O) n requires fewer water molecules than those for MgCl 2 (H 2 O) n . Coincidentally, the solubility of calcium chloride is higher than that of magnesium chloride in bulk solutions.

  11. Sputtering and reflection of self-bombardment of tungsten material

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Guo-jian [University of Science and Technology of China, Hefei (China); Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Li, Xiao-chun; Xu, Qian; Yang, Zhong-shi [Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Luo, Guang-nan, E-mail: gnluo@ipp.ac.cn [University of Science and Technology of China, Hefei (China); Institute of Plasma Physics Chinese Academy of Sciences, Hefei (China); Hefei Center for Physical Science and Technology, Hefei (China); Hefei Science Center of CAS, Hefei (China)

    2015-04-15

    In present research, the sputtering and reflection yield of self-bombardment of tungsten are investigated with the aid of molecular dynamics simulations. The source of sputtered and reflected atoms is detected by traced the original locations of sputtered and reflected atoms. Results show that for the reflected atoms no specific region exists which means cluster atoms are randomly reflected. But almost all of sputtered atoms are from a conical region under the landing point of cluster. So we can determine the sputtering yield by study the dimension of the sputtering region. Molecular dynamics shows the depth and radius of the conical are power functions of impacting energy. The effects of cluster size and temperature of target on sputtering and reflection rate are also preformed in present study. Both sputtering and reflection yield are proportion to cluster size in present cluster size, i.e. 66–2647 atoms. Higher target temperature can increase sputtering yield and deduce sputtering threshold energy, but little effect on reflection rate.

  12. Sputtering and reflection of self-bombardment of tungsten material

    International Nuclear Information System (INIS)

    Niu, Guo-jian; Li, Xiao-chun; Xu, Qian; Yang, Zhong-shi; Luo, Guang-nan

    2015-01-01

    In present research, the sputtering and reflection yield of self-bombardment of tungsten are investigated with the aid of molecular dynamics simulations. The source of sputtered and reflected atoms is detected by traced the original locations of sputtered and reflected atoms. Results show that for the reflected atoms no specific region exists which means cluster atoms are randomly reflected. But almost all of sputtered atoms are from a conical region under the landing point of cluster. So we can determine the sputtering yield by study the dimension of the sputtering region. Molecular dynamics shows the depth and radius of the conical are power functions of impacting energy. The effects of cluster size and temperature of target on sputtering and reflection rate are also preformed in present study. Both sputtering and reflection yield are proportion to cluster size in present cluster size, i.e. 66–2647 atoms. Higher target temperature can increase sputtering yield and deduce sputtering threshold energy, but little effect on reflection rate

  13. Reactive sputter deposition

    CERN Document Server

    Mahieu, Stijn

    2008-01-01

    In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.

  14. Sputtering of solid nitrogen by keV helium ions

    DEFF Research Database (Denmark)

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

    1993-01-01

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

  15. Rational design of organic superconductors through the use of the large, discrete molecular anions M(CF3)4-(M = Cu, Ag, Au) and SO3CF2CH2SF5-

    International Nuclear Information System (INIS)

    Schlueter, J.A.; Geiser, U.; Williams, J.M.

    1996-01-01

    A new approach to synthesis of organic superconductors has recently been pioneered which involves the use of large discrete molecular anions as the charge-compensating entities in these charge transfer salts. The organic electron-donor molecule bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) has been electrocrystallized with the novel organometallic M(CF 3 ) 4 - (M=Cu, Ag, Au) anions in a variety of 1,1,2-trihaloethane solvents. Over 20 organic superconductors have been synthesized which can be described by (ET) 2 M(CF 3 ) 4 (1,1,2- trihaloethane). These solvated salts are shown to have highly anisotropic physical properties which can be tuned via modifications of each of their three molecular components: ET electron donor molecule, M(CF 3 ) 4 - anion, and neutral 1,1,2- trihaloethane solvent molecule. Superconductivity has also been observed in an ET salt containing the discrete SF 5 CH 2 CF 2 SO 3 - anion with onset temperature near 5.2 K

  16. Density-functional molecular-dynamics study of the redox reactions of two anionic, aqueous transition-metal complexes

    International Nuclear Information System (INIS)

    Tateyama, Yoshitaka; Blumberger, Jochen; Sprik, Michiel; Tavernelli, Ivano

    2005-01-01

    The thermochemistry of the RuO 4 2- +MnO 4 - →RuO 4 - +MnO 4 2- redox reaction in aqueous solution is studied by separate density-functional-based ab initio molecular-dynamics simulations of the component half reactions RuO 4 2- →RuO 4 - +e - and MnO 4 2- →MnO 4 - +e - . We compare the results of a recently developed grand-canonical method for the computation of oxidation free energies to the predictions by the energy-gap relations of the Marcus theory that can be assumed to apply to these reactions. The calculated redox potentials are in good agreement. The subtraction of the half-reaction free energies gives an estimate of the free energy of the full reaction. The result obtained from the grand-canonical method is -0.4 eV, while the application of the Marcus theory gives -0.3 eV. These should be compared to the experimental value of 0.0 eV. Size effects, in response to increasing the number of water molecules in the periodic model system from 30 to 48, are found to be small (≅0.1 eV). The link to the Marcus theory also has enabled us to compute reorganization free energies for oxidation. For both the MnO 4 2- and RuO 4 2- redox reactions we find the same reorganization free energy of 0.8 eV (1.0 eV in the larger system). The results for the free energies and further analysis of solvation and electronic structure confirm that these two tetrahedral oxoanions show very similar behavior in solution in spite of the central transition-metal atoms occupying a different row and column in the periodic table

  17. High-precision molecular dynamics simulation of UO2–PuO2: Anion self-diffusion in UO2

    International Nuclear Information System (INIS)

    Potashnikov, S.I.; Boyarchenkov, A.S.; Nekrasov, K.A.; Kupryazhkin, A.Ya.

    2013-01-01

    Highlights: ► We perform MD simulation of oxygen diffusion in UO2 (up to 50 000 ions and 1 μs time). ► We reached 1400 K and 10 −12 cm 2 /sec, which allowed direct comparison to experiments. ► S-shaped T-dependence of activation energy and λ-peak of its derivative were obtained. ► Continual superionic phase transition (rather than first or second order) was proved. ► Activation energy of exchange diffusion equals anti-Frenkel defect formation energy. -- Abstract: Our series of articles is devoted to high-precision molecular dynamics simulation of mixed actinide-oxide (MOX) fuel in the approximation of rigid ions and pair interactions (RIPI) using high-performance graphics processors (GPU). In this article we study self-diffusion mechanisms of oxygen anions in uranium dioxide (UO 2 ) with the 10 recent and widely used sets of interatomic pair potentials (SPP) under periodic (PBC) and isolated (IBC) boundary conditions. Wide range of measured diffusion coefficients (from 10 −3 cm 2 /s at melting point down to 10 −12 cm 2 /s at 1400 K) made possible a direct comparison (without extrapolation) of the simulation results with the experimental data, which have been known only at low temperatures (T < 1500 K). A highly detailed (with the temperature step of 1 K) calculation of the diffusion coefficient allowed us to plot temperature dependences of the diffusion activation energy and its derivative, both of which show a wide (∼1000 K) superionic transition region confirming the broad λ-peaks of heat capacity obtained by us earlier. It is shown that regardless of SPP the anion self-diffusion in model crystals without surface or artificially embedded defects goes on via exchange mechanism, rather than interstitial or vacancy mechanisms suggested by the previous works. The activation energy of exchange diffusion turned out to coincide with the anti-Frenkel defect formation energy calculated by the lattice statics

  18. MD simulation of cluster formation during sputtering

    International Nuclear Information System (INIS)

    Muramoto, T.; Okai, M.; Yamashita, Y.; Yorizane, K.; Yamamura, Y.

    2001-01-01

    The cluster ejection due to cluster impact on a solid surface is studied through molecular dynamics (MD) simulations. Simulations are performed for Cu cluster impacts on the Cu(1 1 1) surface for cluster energy 100 eV/atom, and for clusters of 6, 13, 28 and 55 atoms. Interatomic interactions are described by the AMLJ-EAM potential. The vibration energy spectrum is independent of the incident cluster size and energy. This comes from the fact that sputtered clusters become stable through the successive fragmentation of nascent large sputtered clusters. The vibration energy spectra for large sputtered clusters have a peak, whose energy corresponds to the melting temperature of Cu. The exponent of the power-law fit of the abundance distribution and the total sputtering yield for the cluster impacts are higher than that for the monatomic ion impacts with the same total energy, where the exponent δ is given by Y n ∝n δ and Y n is the yield of sputtered n-atom cluster. The exponent δ follows a unified function of the total sputtering yield, which is a monotonic increase function, and it is nearly equal to δ ∼ -3 for larger yield

  19. The influence of landing points on the sputtering of mono-crystal solids due to cluster impacting

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Guo-jian; Li, Xiao-chun; Xu, Qian; Yang, Zhong-shi, E-mail: zsyang@ipp.ac.cn; Luo, Guang-nan, E-mail: gnluo@ipp.ac.cn

    2017-01-15

    The mechanism of sputtering due to cluster impacting which has been widely studied is an important but unsolved problem. In present research, we discuss the effect of the landing point on the sputtering with the method of molecular dynamics. The results show that the landing points play significant roles on sputter yield when the temperature of target is low. Specific landing points can cause particular sputtering patterns which lead to different sputtering yield and moving directions of sputtered atoms. The mechanism of this phenomenon is that specific landing keeps symmetries and anisotropies of target lattice, which influence the sputtering yield.

  20. Sputtering of water ice

    DEFF Research Database (Denmark)

    Baragiola, R.A.; Vidal, R.A.; Svendsen, W.

    2003-01-01

    We present results of a range of experiments of sputtering of water ice together with a guide to the literature. We studied how sputtering depends on the projectile energy and fluence, ice growth temperature, irradiation temperature and external electric fields. We observed luminescence from...

  1. Argonne inverted sputter source

    International Nuclear Information System (INIS)

    Yntema, J.L.; Billquist, P.J.

    1983-01-01

    The emittance of the inverted sputter source with immersion lenses was measured to be about 5π mm mrad MeV/sup 1/2/ at the 75% level over a wide range of beam intensities. The use of the source in experiments with radioactive sputter targets and hydrogen loaded targets is described. Self contamination of the source is discussed

  2. Influence of a Counterion on the Ion Atmosphere of an Anion: A Molecular Dynamics Study of LiX and CsX (X = F(-), Cl(-), I(-)) in Methanol.

    Science.gov (United States)

    Kumar, Parveen; Kulkarni, Anant D; Yashonath, S

    2015-08-27

    We report molecular dynamics (MD) simulations to explore the influence of a counterion on the structure and dynamics of cationic and anionic solvation shells for various ions in methanol at 298 K. We show that the variation in ionic size of either the cation or the anion in an ion pair influences the solvation structure of the other ion as well as the diffusivity in an electrolyte solution of methanol. The extent of ionic association between the cation and its counteranion of different ionic sizes has been investigated by analyzing the radial distribution functions (RDFs) and the orientation of methanol molecules in the first solvation shell (FSS) of ions. It is shown that the methanol in the FSS of the anion as well the cation exhibit quite different radial and orientational structures as compared to methanol which lie in the FSS of either the anion or the cation but not both. We find that the coordination number (CN) of F(-), Cl(-), and I(-) ions decreases with increasing size of the anion which is contrary to the trend reported for the anions in H2O. The mean residence time (MRT) of methanol molecules in the FSS of ions has been calculated using the stable states picture (SSP) approach. It is seen that the ion-counterion interaction has a considerable influence on the MRT of methanol molecules in the FSS of ions. We also discuss the stability order of the ion-counterion using the potentials of mean force (PMFs) for ion pairs with ions of different sizes. The PMF plots reveal that the Li(+)-F(-) pair (small-small) is highly stable and the Li(+)-I(-) pair is least stable (small-large) in electrolyte solutions.

  3. Formation of interstellar anions

    Science.gov (United States)

    Senent, Maria Luisa

    2012-05-01

    Formation of interstellar anions: M.L. Senent. The recent detection of negative charged species in the ISM1 has instigated enthusiasm for anions in the astrophysical community2. Many of these species are new and entail characterization. How they are formed in astrophysical sources is a question of major relevance. The anion presence in ISM was first predicted theoretically on the basis of electron affinities and on the negative linear chain molecular stabilities. Although very early, they were considered in astrochemical models3-4, their discovery is so recent because their abundances seem to be relatively low. These have to be understood in terms of molecular stabilities, reaction probabilities and radiative and collisional excitations. Then, we present our theoretical work on even carbon chains type Cn and CnH (n=2,4,6) focused to the understanding of anion abundances. We use highly correlated ab initio methods. We performed spectroscopic studies of various isomers that can play important roles as intermediates5-8. In previous papers9-10, we compared C2H and C2H- collisional rates responsible for observed line intensities. Actually, we study hydrogen attachment (Cn +H → CnH and Cn- +H → CnH-) and associative detachment processes (Cn- +H → CnH +e-) for 2, 4 and 6 carbon atom chains11. [1] M.C.McCarthy, C.A.Gottlieb, H.Gupta, P.Thaddeus, Astrophys.J, 652, L141 (2006) [2] V.M.Bierbaum, J.Cernicharo, R.Bachiller, eds., 2011, pp 383-389. [3] A. Dalgarno, R.A. Mc Cray, Astrophys.J,, 181, 95 (1973) [4] E. Herbst E., Nature, 289, 656 (1981); [5] H.Massó, M.L.Senent, P.Rosmus, M.Hochlaf, J.Chem.Phys., 124, 234304 (2006) [6] M.L.Senent, M.Hochlaf, Astrophys. J. , 708, 1452(2010) [7] H.Massó, M.L.Senent, J.Phys.Chem.A, 113, 12404 (2009) [8] D. Hammoutene, M.Hochlaf, M.L.Senent, submitted. [9] A. Spielfiedel, N. Feautrier, F. Najar, D. ben Abdallah, F. Dayou, M.L. Senent, F. Lique, Mon.Not.R.Astron.Soc., 421, 1891 (2012) [10] F.Dumouchel, A, Spielfieldel , M

  4. The statistics of sputtering

    International Nuclear Information System (INIS)

    Robinson, M.T.

    1993-01-01

    The MARLOWE program was used to study the statistics of sputtering on the example of 1- to 100-keV Au atoms normally incident on static (001) and (111) Au crystals. The yield of sputtered atoms was examined as a function of the impact point of the incident particles (''ions'') on the target surfaces. There were variations on two scales. The effects of the axial and planar channeling of the ions could be traced, the details depending on the orientation of the target and the energies of the ions. Locally, the sputtering yield was very sensitive to the impact point, small changes in position often producing large changes yield. Results indicate strongly that the sputtering yield is a random (''chaotic'') function of the impact point

  5. Sputtering and mixing of supported nanoparticles

    International Nuclear Information System (INIS)

    Jiménez-Sáez, J.C.; Pérez-Martín, A.M.C.; Jiménez-Rodríguez, J.J.

    2013-01-01

    Sputtering and mixing of Co nanoparticles supported in Cu(0 0 1) under 1-keV argon bombardment are studied using molecular-dynamics simulations. Particles of different initial size have been considered. The cluster height decreases exponentially with increasing fluence. In nanoparticles, sputtering yield is significantly enhanced compared to bulk. In fact, the value of this magnitude depends on the cluster height. A theoretical model for sputtering is introduced with acceptable results compared to those obtained by simulation. Discrepancies happen mainly for very small particles. Mixing rate at the interface is quantified; and besides, the influence of border effects for clusters of different initial size is assessed. Mixing rate and border length–surface area ratio for the initial interface show a proportionality relation. The phenomenon of ion-induced burrowing of metallic nanoparticles is analysed

  6. Sputtering and inelastic processes

    International Nuclear Information System (INIS)

    Baranov, I.A.; Tsepelevic, S.O.

    1987-01-01

    Experimental data and models of a new type of material sputtering with ions of relatively high energies due to inelastic (electron) processes are reviewed. This area of investigations began to develop intensively during the latest years. New experimental data of the authors on differential characteristics of ultradisperse gold and americium dioxide layers with fission fragments are given as well. Practical applications of the new sputtering type are considered as well as setup of possibl experiments at heavy multiply charged ion accelerators

  7. Computer simulation of sputtering: A review

    International Nuclear Information System (INIS)

    Robinson, M.T.; Hou, M.

    1992-08-01

    In 1986, H. H. Andersen reviewed attempts to understand sputtering by computer simulation and identified several areas where further research was needed: potential energy functions for molecular dynamics (MD) modelling; the role of inelastic effects on sputtering, especially near the target surface; the modelling of surface binding in models based on the binary collision approximation (BCA); aspects of cluster emission in MD models; and angular distributions of sputtered particles. To these may be added kinetic energy distributions of sputtered particles and the relationships between MD and BCA models, as well as the development of intermediate models. Many of these topics are discussed. Recent advances in BCA modelling include the explicit evaluation of the time in strict BCA codes and the development of intermediate codes able to simulate certain many-particle problems realistically. Developments in MD modelling include the wide-spread use of many-body potentials in sputtering calculations, inclusion of realistic electron excitation and electron-phonon interactions, and several studies of cluster ion impacts on solid surfaces

  8. Ab initio studies of O2-(H2O)n and O3-(H2O)n anionic molecular clusters, n≤12

    DEFF Research Database (Denmark)

    Bork, Nicolai Christian; Kurtén, T.; Enghoff, Martin Andreas Bødker

    2011-01-01

    that anionic O2−(H2O)n and O3−(H2O)n clusters are thermally stabilized at typical atmospheric conditions for at least n = 5. The first 4 water molecules are strongly bound to the anion due to delocalization of the excess charge while stabilization of more than 4 H2O is due to normal hydrogen bonding. Although...... clustering up to 12 H2O, we find that the O2 and O3 anions retain at least ca. 80 % of the charge and are located at the surface of the cluster. The O2− and O3− speicies are thus accessible for further reactions. Finally, the thermodynamics of a few relevant cluster reactions are considered....

  9. Ab initio studies of O-2(-) (H2O)(n) and O-3(-) (H2O)(n) anionic molecular clusters, n

    DEFF Research Database (Denmark)

    Bork, Nicolai Christian; Kurten, T.; Enghoff, Martin Andreas Bødker

    2011-01-01

    that anionic O-2(-)(H2O)n and O-3(-)(H2O)n clusters are thermally stabilized at typical atmospheric conditions for at least n = 5. The first 4 water molecules are strongly bound to the anion due to delocalization of the excess charge while stabilization of more than 4 H2O is due to normal hydrogen bonding....... Although clustering up to 12 H2O, we find that the O-2 and O-3 anions retain at least ca. 80 % of the charge and are located at the surface of the cluster. The O-2(-) and O-3(-) speicies are thus accessible for further reactions. We consider the distributions of cluster sizes as function of altitude before...

  10. Plasma diagnostic studies of the influence of process variables upon the atomic and molecular species ejected from (1-x)Li4SiO4:xLi3PO4 targets during rf-magnetron sputtering

    International Nuclear Information System (INIS)

    Wachs, A.L.; Bates, J.B.; Dudney, N.J.; Luck, C.F.

    1990-01-01

    The deposition of thin-film electrolytes is a critical step in the development of lithium microbatteries with the potential for circuit integration. We have performed a preliminary study of the rf-magnetron sputtering of (1-x)Li 4 SiO 4 :xLi 3 PO 4 targets used to deposit amorphous thin-film electrolytes formed of the three-component system Li 2 O--SiO 2 --P 2 O 5 . Mass and optical emission spectroscopies have been used to investigate the effects of target composition and the deposition conditions upon the atomic and molecular species ejected from the targets. The data provide important information for understanding the mechanism of film formation and for monitoring the Li atomic flux onto the substrates during film growth. 5 refs., 7 figs., 1 tab

  11. Photo-driven electron transfer from the highly reducing excited state of naphthalene diimide radical anion to a CO 2 reduction catalyst within a molecular triad

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Jose F. [Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center; Northwestern University; Evanston; USA; La Porte, Nathan T. [Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center; Northwestern University; Evanston; USA; Mauck, Catherine M. [Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center; Northwestern University; Evanston; USA; Wasielewski, Michael R. [Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center; Northwestern University; Evanston; USA

    2017-01-01

    The naphthalene-1,4:5,8-bis(dicarboximide) radical anion (NDI-˙), which is easily produced by mild chemical or electrochemical reduction (-0.5 Vvs.SCE), can be photoexcited at wavelengths as long as 785 nm, and has an excited state (NDI-˙*) oxidation potential of -2.1 Vvs.SCE, making it a very attractive choice for artificial photosynthetic systems that require powerful photoreductants, such as CO2 reduction catalysts. However, once an electron is transferred from NDI-˙* to an acceptor directly bound to it, a combination of strong electronic coupling and favorable free energy change frequently make the back electron transfer rapid. To mitigate this effect, we have designed a molecular triad system comprising an NDI-˙ chromophoric donor, a 9,10-diphenylanthracene (DPA) intermediate acceptor, and a Re(dmb)(CO)3carbon dioxide reduction catalyst, where dmb is 4,4'-dimethyl-2,2'-bipyridine, as the terminal acceptor. Photoexcitation of NDI-˙ to NDI-˙* is followed by ultrafast reduction of DPA to DPA-˙, which then rapidly reduces the metal complex. The overall time constant for the forward electron transfer to reduce the metal complex is τ = 20.8 ps, while the time constant for back-electron transfer is six orders of magnitude longer, τ = 43.4 μs. Achieving long-lived, highly reduced states of these metal complexes is a necessary condition for their use as catalysts. The extremely long lifetime of the reduced metal complex is attributed to careful tuning of the redox potentials of the chromophore and intermediate acceptor. The NDI-˙–DPA fragment presents many attractive features for incorporation into other photoinduced electron transfer assemblies directed at the long-lived photosensitization of difficult-to-reduce catalytic centers.

  12. Fundamental aspects of cathodic sputtering

    International Nuclear Information System (INIS)

    Harman, R.

    1979-01-01

    The main fundamental aspects and problems of cathodic sputtering used mainly for thin film deposition and sputter etching are discussed. Among many types of known sputtering techniques the radiofrequency /RF/ diode sputtering is the most universal one and is used for deposition of metals, alloys, metallic compounds, semiconductors and insulators. It seems that nowadays the largest number of working sputtering systems is of diode type. Sometimes also the dc or rf triode sputtering systems are used. The problems in these processes are practically equivalent and comparable with the problems in the diode method and therefore our discussion will be, in most cases applicable for both, the diode and triode methods

  13. Anion channels: master switches of stress responses.

    Science.gov (United States)

    Roelfsema, M Rob G; Hedrich, Rainer; Geiger, Dietmar

    2012-04-01

    During stress, plant cells activate anion channels and trigger the release of anions across the plasma membrane. Recently, two new gene families have been identified that encode major groups of anion channels. The SLAC/SLAH channels are characterized by slow voltage-dependent activation (S-type), whereas ALMT genes encode rapid-activating channels (R-type). Both S- and R-type channels are stimulated in guard cells by the stress hormone ABA, which leads to stomatal closure. Besides their role in ABA-dependent stomatal movement, anion channels are also activated by biotic stress factors such as microbe-associated molecular patterns (MAMPs). Given that anion channels occur throughout the plant kingdom, they are likely to serve a general function as master switches of stress responses. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Anion exchange membrane

    Science.gov (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  15. Implantation, recoil implantation, and sputtering

    International Nuclear Information System (INIS)

    Kelly, R.

    1984-01-01

    The implantation and sputtering mechanisms which are relevant to ion bombardment of surfaces are described. These are: collision, thermal, electronic and photon-induced sputtering. 135 refs.; 36 figs.; 9 tabs

  16. Physics of ion sputtering

    International Nuclear Information System (INIS)

    Robinson, M.T.

    1984-04-01

    The ejection of atoms by the ion bombardment of solids is discussed in terms of linear collision cascade theory. A simple argument describes the energies of the ejecta, but elaborate models are required to obtain accurate sputtering yields and related quantities. These include transport theoretical models based on linearized Boltzmann equations, computer simulation models based on the binary collision approximation, and classical many-body dynamical models. The role of each kind of model is discussed. Several aspects of sputtering are illustrated by results from the simulation code MARLOWE. 20 references, 6 figures

  17. Proton sputtering. Final report

    International Nuclear Information System (INIS)

    Finfgeld, C.R.

    1975-01-01

    This research provides sputtering yields as a function of energy for H + and D + on several representative pure metallic elements, in the absence of surface contaminants. The experimental technique and apparatus are described. Data are given for Au, Co, Ta, W, and Mo

  18. Laser sputtering. Pt. 1

    International Nuclear Information System (INIS)

    Kelly, R.; Cuomo, J.J.; Leary, P.A.; Rothenburg, J.E.; Braren, B.E.; Aliotta, C.F.

    1985-01-01

    Irradiation, i.e. bombardment, with 193 nm laser pulses having an energy fluence of 2.5 J/cm 2 and a duration of proportional12 ns leads to rapid sputtering with Au, Al 2 O 3 , MgO, MgO.Al 2 O 3 , SiO 2 , glass, and LaB 6 , relatively slow sputtering with MgF 2 and diamond, and mainly thermal-stress cracking with W. Scanning electron microscopy (SEM) suggests that the mechanism for the sputtering of Au in either vacuum or air is one based on the hydrodynamics of molten Au, while an SEM-derived surface temperature estimate confirms that thermal sputtering (which might have been expected) is not possible. SEM with W shows that the near total lack of material removal is due to the thermal-stress cracking not leading to completed exfoliation, together with the surface temperature being too low for either hydrodynamical or thermal processes. Corresponding SEM with Al 2 O 3 shows, in the case of specimens bombarded in vacuum, topography of such a type that all mechanisms except electronic ones can be ruled out. The topography of Al 2 O 3 or other oxides bombarded in air through a mask is somewhat different, showing craters as for vacuum bombardments but ones which have a cone-like pattern on the bottom. (orig.)

  19. Geometric considerations in magnetron sputtering

    International Nuclear Information System (INIS)

    Thornton, J.A.

    1982-01-01

    The recent development of high performance magnetron type discharge sources has greatly enhaced the range of coating applications where sputtering is a viable deposition process. Magnetron sources can provide high current densities and sputtering rates, even at low pressures. They have much reduced substrate heating rates and can be scaled to large sizes. Magnetron sputter coating apparatuses can have a variety of geometric and plasma configurations. The target geometry affects the emission directions of both the sputtered atoms and the energetic ions which are neutralized and reflected at the cathode. This fact, coupled with the long mean free particle paths which are prevalent at low pressures, can make the coating properties very dependent on the apparatus geometry. This paper reviews the physics of magnetron operation and discusses the influences of apparatus geometry on the use of magnetrons for rf sputtering and reactive sputtering, as well as on the microstructure and internal stresses in sputtered metallic coatings. (author) [pt

  20. Theoretical Probing of Weak Anion-Cation Interactions in Certain Pyridinium-Based Ionic Liquid Ion Pairs and the Application of Molecular Electrostatic Potential in Their Ionic Crystal Density Determination: A Comparative Study Using Density Functional Approach.

    Science.gov (United States)

    Joseph, Aswathy; Thomas, Vibin Ipe; Żyła, Gaweł; Padmanabhan, A S; Mathew, Suresh

    2018-01-11

    A comprehensive study on the structure, nature of interaction, and properties of six ionic pairs of 1-butylpyridinium and 1-butyl-4-methylpyridinium cations in combination with tetrafluoroborate (BF 4 - ), chloride (Cl - ), and bromide (Br - ) anions have been carried out using density functional theory (DFT). The anion-cation interaction energy (ΔE int ), thermochemistry values, theoretical band gap, molecular orbital energy order, DFT-based chemical activity descriptors [chemical potential (μ), chemical hardness (η), and electrophilicity index (ω)], and distribution of density of states (DOS) of these ion pairs were investigated. The ascendancy of the -CH 3 substituent at the fourth position of the 1-butylpyridinium cation ring on the values of ΔE int , theoretical band gap and chemical activity descriptors was evaluated. The ΔE int values were negative for all six ion pairs and were highest for Cl - containing ion pairs. The theoretical band gap value after -CH 3 substitution increased from 3.78 to 3.96 eV (for Cl - ) and from 2.74 to 2.88 eV (for Br - ) and decreased from 4.9 to 4.89 eV (for BF 4 - ). Ion pairs of BF 4 - were more susceptible to charge transfer processes as inferred from their significantly high η values and comparatively small difference in ω value after -CH 3 substitution. The change in η and μ values due to the -CH 3 substituent is negligibly small in all cases except for the ion pairs of Cl - . Critical-point (CP) analyses were carried out to investigate the AIM topological parameters at the interionic bond critical points (BCPs). The RDG isosurface analysis indicated that the anion-cation interaction was dominated by strong H cat ···X ani and C cat ···X ani interactions in ion pairs of Cl - and Br - whereas a weak van der Waal's effect dominated in ion pairs of BF 4 - . The molecular electrostatic potential (MESP)-based parameter ΔΔV min measuring the anion-cation interaction strength showed a good linear correlation with

  1. Sputtering of nano-grains by energetic ions

    CERN Document Server

    Bringa, E M

    2002-01-01

    Sputtering from grains with a size of tens of nanometers is important in a number of astrophysical environments having a variety of plasma properties and can have applications in nano-technology. Since energy deposition by incident ions or electrons can create 'hot' regions in a small grain, thermal spike (TS) models have been applied to estimate the sputtering. The excitations produced by a fast ion are often assumed to form a 'hot' cylindrical track. In this paper we use molecular dynamics (MD) calculations to describe the energy transport and sputtering due to the creation of a 'hot' track in a grain with one quarter million atoms. We show the enhancement due to grain size and find that TS models work over a limited range of excitation densities. Discrepancies of several orders of magnitude are found when comparing our MD results for sputtering of small dust grains to those obtained by the astrophysical community using spike models.

  2. Electronic sputtering of biomolecules and its application in mass spectrometry

    International Nuclear Information System (INIS)

    Haakansson, P.; Sundqvist, B.U.R.

    1989-01-01

    In 1974 Macfarlane discovered that fast heavy ions from a 252-Cf source can desorb and ionize molecules from a solid surface. The mass of the molecules was determined by time-of-flight technique. It has been shown that the desorption mechanism is associated with the electron part of the stopping power of the primary ion and the name 'electron sputtering' has been adopted for the phenomenon to distinguish it from the well-known sputtering process with ions of KeV energy. A review of electronic sputtering of biomolecules will be given as well as recent measurements on Langmuir-Blodgett films. One important application of electronic sputtering is in the field of mass spectrometry. With this technique large and nonvolatile molecules can be studied. Particularly adsorption of biomolecules to a nitrocellulose backing has proven to be very useful. Examples will be given of mass spectra from peptides with a molecular weight above 20,000 u. (author)

  3. Synthesis of cationic diphosphine ruthenium complexes with nido-dicarbaundecaborate anions. Molecular structure of [RuCl(dppe)2]+[7,8-nido-C2B9H12]-

    International Nuclear Information System (INIS)

    Cheredilin, D.N.; Dolgushin, F.M.; Balagurova, E.V.; Godovikov, I.A.; Chizhevskij, I.T.

    2004-01-01

    Five new diphosphine ruthenium(II) complexes with nido-dicarbaundecaborate anions were synthesized. The composition and structure of the complexes were confirmed by data of 1 H, 31 P{ 1 H} NMR and elementary analysis. The crystal and molecular structure of solvated complex [RuCl(dppe) 2 + [7,8-nido-C 2 B 9 H 12 ] - ·CH 2 Cl 2 was ascertained by the method of X-ray diffraction analysis. It is shown that coordination sphere of ruthenium atom in the complex cation is a distorted trigonal bipyramid. The distances from ruthenium atom to phosphorus atoms are 2.398(1) and 2.391(1) A, while the angle P-Ru-P equals 175.85(5) Deg [ru

  4. Molecular rheology of branched polymers: Decoding and exploring the role of architectural dispersity through a synergy of anionic synthesis, interaction chromatography, rheometry and modeling

    KAUST Repository

    Van Ruymbeke, Evelyne; Lee, Heecheong; Chang, Taihyun; Nikopoulou, Anastasia; Hadjichristidis, Nikolaos; Snijkers, Frank; Vlassopoulos, Dimitris

    2014-01-01

    the current state-of-the-art. Here we review this interdisciplinary approach to molecular rheology of complex polymers, and show the importance of confronting these different tools for ensuring an accurate characterization of a given polymeric sample. We use

  5. Theory of thermal sputtering

    International Nuclear Information System (INIS)

    Kelly, R.

    1977-01-01

    An energetic ion which is incident on a solid target causes a momentary temperature increase in the impact region, i.e., a so-called thermal spike occurs. Such spikes are capable of causing (or supplementing) disordering, precipitation, crystallization, electronic excitation, stoichiometry change, desorption, and sputtering, it being the contribution to sputtering that is considered here. The approach used is compatible with modern damage-distribution theory. Thus the temperature profile left by the incident ion is taken as a three-dimensional Gaussian with parameters appropriate to power-law scattering, and is used as the initial condition for solving the heat-conduction equation. Let us write this solution as T = T(t, y), where t is time and y is a dimension parallel to the target surface. The vaporization flux from a solid surface is taken as pnsup(1/2)(2π 2 >kT)sup(-1/2), where p, the equilibrium pressure of a vapor species containing n atoms, can be written as p 0 exp(-L/T), p 0 and L are constants largely independent of temperature, and 2 > is the mean mass per atom of target. An equation for the thermal sputtering coefficient is given: after integration the final result takes the form: Ssub(thermal)=pnsup(1/2)[2π 2 >k(Tsub(infinity)+cΔT 0 )]sup(-1/2)πlambda 2 tsub(eff.)atoms/ion, where Tsub(infinity) is the macroscopic target temperature, cΔT 0 is the maximum temperature increase at x = y = 0, p is to be evaluated at T = Tsub(infinity) + cΔT 0 , lambda is the mean atomic spacing of the target, and tsub(eff.) is a quantity with units of time. (author)

  6. Zero-point energy effects in anion solvation shells.

    Science.gov (United States)

    Habershon, Scott

    2014-05-21

    By comparing classical and quantum-mechanical (path-integral-based) molecular simulations of solvated halide anions X(-) [X = F, Cl, Br and I], we identify an ion-specific quantum contribution to anion-water hydrogen-bond dynamics; this effect has not been identified in previous simulation studies. For anions such as fluoride, which strongly bind water molecules in the first solvation shell, quantum simulations exhibit hydrogen-bond dynamics nearly 40% faster than the corresponding classical results, whereas those anions which form a weakly bound solvation shell, such as iodide, exhibit a quantum effect of around 10%. This observation can be rationalized by considering the different zero-point energy (ZPE) of the water vibrational modes in the first solvation shell; for strongly binding anions, the ZPE of bound water molecules is larger, giving rise to faster dynamics in quantum simulations. These results are consistent with experimental investigations of anion-bound water vibrational and reorientational motion.

  7. Molecular properties of mammalian proteins that interact with cGMP: protein kinases, cation channels, phosphodiesterases, and multi-drug anion transporters.

    Science.gov (United States)

    Francis, Sharron H; Blount, Mitsi A; Zoraghi, Roya; Corbin, Jackie D

    2005-09-01

    Cyclic GMP is a critical second messenger signaling molecule in many mammalian cell types. It is synthesized by a family of guanylyl cyclases that is activated in response to stimuli from hormones such as natriuretic peptides, members of the guanylin family, and chemical stimuli including nitric oxide and carbon monoxide. The resulting elevation of cGMP modulates myriad physiological processes. Three major groups of cellular proteins bind cGMP specifically at allosteric sites; interaction of cGMP with these sites modulates the activities and functions of other domains within these protein groups to bring about physiological effects. These proteins include the cyclic nucleotide (cN)-dependent protein kinases, cN-gated cation channels, and cGMP-binding phosphodiesterases (PDE). Cyclic GMP also interacts with the catalytic sites of many cN PDEs and with some members of the multi-drug anion transporter family (MRPs) which can extrude nucleotides from cells. The allosteric cN-binding sites in the kinases and the cN-gated channels are evolutionarily and biochemically related, whereas the allosteric cGMP-binding sites in PDEs (also known as GAF domains), the catalytic sites of PDEs , and the ligand-binding sites in the MRPs are evolutionarily and biochemically distinct from each other and from those in the kinase and channel families. The sites that interact with cGMP within each of these groups of proteins have unique properties that provide for cGMP binding. Within a given cell, cGMP can potentially interact with members of all these groups of proteins if they are present. The relative abundance and affinities of these various cGMP-binding sites in conjunction with their subcellular compartmentation, proximity to cyclases and PDEs, and post-translational modification contribute importantly in determining the impact of these respective proteins to cGMP signaling within a particular cell.

  8. Combining research in physical chemistry and chemical education: Part A. The femtosecond molecular dynamics of small gas-phase anion clusters. Part B. Surveying student beliefs about chemistry and the development of physical chemistry learning tutorials

    Science.gov (United States)

    Barbera, Jack

    2007-12-01

    This dissertation combines work in the areas of experimental physical chemistry and chemical education. In the area of physical chemistry, femtosecond pump-probe spectroscopy is used to interrogate the time-dependence for energy redistribution, solvent reorientation, and dissociation dynamics in small gas-phase anion clusters. The chemical education research addressed in this manuscript include the development and validation of a survey to measure students' beliefs about chemistry and the learning of chemistry and the development and testing of learning tutorials for use in undergraduate physical chemistry courses in thermodynamics and kinetics. In the first part of this dissertation, the Cu(CD3OD) dynamics are investigated using a combination of femtosecond pump-probe experiments and ab initio calculations. Dissociation of this complex into Cu and CD3OD occurs on two distinct time scales: 3 and 30 ps, which arise, respectively, from the coupling of intermolecular solvent rotations and excited methyl rotor rotation into the Cu-O dissociation component upon electron photodetachment of the precursor anion. In the second part of this dissertation, the time-resolved recombination of photodissociated IBr-(CO2)n (n = 5 - 10) cluster anions is investigated. Upon excitation to the A' 2pi 1/2 state of the chromophore, the bare anion results in I- and Br products, upon solvation with CO2, the IBr- chromophore regains near-IR absorption after recombination and vibrational relaxation on the ground electronic state. The recombination times vary with the number of solvent molecules from 12 ps for n = 5 to 900 ps for n = 10. Extensive electronic structure and non-adiabatic molecular dynamic simulations provide a framework to understand this behavior. In the third part of this dissertation, the modification and validation of the Colorado Learning Attitudes about Science Survey (CLASS) for use in chemistry is presented in detail. The CLASS survey is designed to measure student

  9. Structure, solvation, and dynamics of Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, and Ba{sup 2+} complexes with 3-hydroxyflavone and perchlorate anion in acetonitrile medium: A molecular dynamics simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Agieienko, Vira N.; Kolesnik, Yaroslav V.; Kalugin, Oleg N., E-mail: onkalugin@gmail.com [Department of Inorganic Chemistry, V. N. Karazin Kharkiv National University, Kharkiv 61022 (Ukraine)

    2014-05-21

    Molecular dynamics simulations of complexes of Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, and Ba{sup 2+} with 3-hydroxyflavone (flavonol, 3HF) and ClO {sub 4}{sup −} in acetonitrile were performed. The united atoms force field model was proposed for the 3HF molecule using the results of DFT quantum chemical calculations. 3HF was interpreted as a rigid molecule with two internal degrees of freedom, i.e., rotation of the phenyl ring and of the OH group with respect to the chromone moiety. The interatomic radial distribution functions showed that interaction of the cations with flavonol occurs via the carbonyl group of 3HF and it is accompanied with substitution of one of the acetonitrile molecules in the cations’ first solvation shells. Formation of the cation–3HF complexes does not have significant impact on the rotation of the phenyl ring with respect to the chromone moiety. However, the orientation of the flavonol's OH-group is more sensitive to the interaction with doubly charged cations. When complex with Mg{sup 2+} is formed, the OH-group turns out of the plane of the chromone moiety that leads to rupture of intramolecular H-bond in the ligand molecule. Complexation of Ca{sup 2+}, Sr{sup 2+}, and BaClO {sub 4}{sup +} with 3HF produces two structures with different OH-positions, as in the free flavonol with the intramolecular H-bond and as in the complex with Mg{sup 2+} with disrupted H-bonding. It was shown that additional stabilization of the [MgClO{sub 4}(3HF)]{sup +} and [BaClO{sub 4}(3HF)]{sup +} complexes is determined by strong affinity of perchlorate anion to interact with flavonol via intracomplex hydrogen bond between an oxygen atom of the anion and the hydrogen atom of the 3-hydroxyl group. Noticeable difference in the values of the self-diffusion coefficients for Kt{sup 2+} from one side and ClO {sub 4}{sup −}, 3HF, and AN in the cations’ coordination shell from another side implies quite weak interaction between cation, anion, and ligands in

  10. Transition from linear to nonlinear sputtering of solid xenon

    DEFF Research Database (Denmark)

    Dutkiewicz, L.; Pedrys, R.; Schou, Jørgen

    1995-01-01

    Self-sputtering of solid xenon has been studied with molecular dynamics simulations as a model system for the transition from dominantly linear to strongly nonlinear effects. The simulation covered the projectile energy range from 20 to 750 eV. Within a relatively narrow range from 30 to 250 e...

  11. Particle dynamics during electronic sputtering of solid krypton

    DEFF Research Database (Denmark)

    Dutkiewicz, L.; Pedrys, R.; Schou, Jørgen

    1995-01-01

    We have modeled electronic sputtering of solid krypton by excimer production with molecular dynamics. Both excimer evolution in the solid and deexcitation processes have been incorporated in the simulation. The excimer dynamics in the lattice has been analyzed: the excimers formed near the surface...

  12. Patchy proteins, anions and the Hofmeister series

    Energy Technology Data Exchange (ETDEWEB)

    Lund, Mikael; Jungwirth, Pavel [Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo namesti 2, 16610 Prague 6 (Czech Republic); Center for Complex Molecular Systems and Biomolecules, Flemingovo namesti 2, 16610 Prague 6 (Czech Republic)], E-mail: mikael.lund@uochb.cas.cz

    2008-12-10

    We investigate specific anion binding to a range of patchy protein models and use our results to probe protein-protein interactions for aqueous lysozyme solutions. Our molecular simulation studies show that the ion-protein interaction mechanism and strength largely depend on the nature of the interfacial amino acid residues. Via direct ion pairing, small anions interact with charged side-chains while larger anions are attracted to non-polar residues due to several solvent assisted mechanisms. Incorporating ion and surface specificity into a mesoscopic model for protein-protein interactions we calculate the free energy of interaction between lysozyme molecules in aqueous solutions of sodium chloride and sodium iodide. In agreement with experiment, our finding is that 'salting out' follows the reverse Hofmeister series for pH below the iso-electric point and the direct series for pH above pI.

  13. Comparing the Spectroscopic and Molecular Characteristics of Different Dissolved Organic Matter Fractions Isolated by Hydrophobic and Anionic Exchange Resins Using Fluorescence Spectroscopy and FT-ICR-MS

    Directory of Open Access Journals (Sweden)

    Morgane Derrien

    2017-07-01

    Full Text Available Despite the environmental significance of dissolved organic matter (DOM, characterizing DOM is still challenging due to its structural complexity and heterogeneity. In this study, three different chemical fractions, including hydrophobic acid (HPOA, transphilic acid (TPIA, and hydrophilic neutral and base (HPIN/B fractions, were separated from bulk aquatic DOM samples, and their spectral features and the chemical composition at the molecular level were compared using both fluorescence excitation emission matrix-parallel factor analysis (EEM-PARAFAC and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS. The HPIN/B fraction was distinguished from the two acidic fractions (i.e., HPOA and TPIA by the EEM-PARAFAC, while the TPIA fraction was discriminated by using the molecular parameters derived from the FT-ICR MS analyses. Statistical comparison suggests that the spectral dissimilarity among the three chemical fractions might result from the acido-basic properties of DOM samples, while the differences in molecular composition were more likely to be affected by the hydrophobicity of the DOM fractions. The non-metric multidimensional scaling map further revealed that the HPOA was the most heterogeneous among the three fractions. The number of overlapping formulas among the three chemical fractions constituted only <5% of all identified formulas, and those between two different fractions ranged from 2.0% to 24.1%, implying relatively homogeneous properties of the individual chemical fractions with respect to molecular composition. Although employing chemical fractionation achieved a lowering of the DOM heterogeneity, prevalent signatures of either acido-basic property or the hydrophobic nature of DOM on the characteristics of three chemical isolated fractions were not found for this study.

  14. Sputtering. [as deposition technique in mechanical engineering

    Science.gov (United States)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  15. Infrared spectroscopy of anionic hydrated fluorobenzenes

    International Nuclear Information System (INIS)

    Schneider, Holger; Vogelhuber, Kristen M.; Weber, J. Mathias

    2007-01-01

    We investigate the structural motifs of anionic hydrated fluorobenzenes by infrared photodissociation spectroscopy and density functional theory. Our calculations show that all fluorobenzene anions under investigation are strongly distorted from the neutral planar molecular geometries. In the anions, different F atoms are no longer equivalent, providing structurally different binding sites for water molecules and giving rise to a multitude of low-lying isomers. The absorption bands for hexa- and pentafluorobenzene show that only one isomer for the respective monohydrate complexes is populated in our experiment. For C 6 F 6 - ·H 2 O, we can assign these bands to an isomer where water forms a weak double ionic hydrogen bond with two F atoms in the ion, in accord with the results of Bowen et al. [J. Chem. Phys. 127, 014312 (2007), following paper.] The spectroscopic motif of the binary complexes changes slightly with decreasing fluorination of the aromatic anion. For dihydrated hexafluorobenzene anions, several isomers are populated in our experiments, some of which may be due to hydrogen bonding between water molecules

  16. Molecular dynamics simulations of hydrophobous ions at the liquid-liquid interfaces: case of dicarbollide anions as synergy agents and of ionic liquids as extracting medium

    International Nuclear Information System (INIS)

    Chevrot, G.

    2008-01-01

    Based on molecular dynamics simulations, we first describe the distribution of dicarbollide salts (CCD - , Mn + ) in concentrated monophasic solutions (water, chloroform, octanol, nitrobenzene) and in the corresponding biphasic 'oil' - water solutions. We point to the importance of surface activity of the CCD - s and of their self-aggregation in water, with marked counterions effects, and we explain the synergistic effect of CCD - s in the Eu 3+ extraction by BTP ligands. In the second part of the thesis we report exploratory simulations on the extraction of Sr 2+ by 18-crown-6 to an hydrophobic ionic liquid ([BMI][PF6]), focusing on the liquid - liquid interface. Analogies and differences with a classical aqueous interface are outlined. (author)

  17. Interaction of PLGA and trimethyl chitosan modified PLGA nanoparticles with mixed anionic/zwitterionic phospholipid bilayers studied using molecular dynamics simulations

    Science.gov (United States)

    Novak, Brian; Astete, Carlos; Sabliov, Cristina; Moldovan, Dorel

    2012-02-01

    Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable polymer. Nanoparticles of PLGA are commonly used for drug delivery applications. The interaction of the nanoparticles with the cell membrane may influence the rate of their uptake by cells. Both PLGA and cell membranes are negatively charged, so adding positively charged polymers such as trimethyl chitosan (TMC) which adheres to the PLGA particles improves their cellular uptake. The interaction of 3 nm PLGA and TMC-modified-PLGA nanoparticles with lipid bilayers composed of mixtures of phosphatidylcholine and phosphatidylserine lipids was studied using molecular dynamics simulations. The free energy profiles as function of nanoparticles position along the normal direction to the bilayers were calculated, the distribution of phosphatidylserine lipids as a function of distance of the particle from the bilayer was calculated, and the time scale for particle motion in the directions parallel to the bilayer surface was estimated.

  18. Depth of origin of atoms sputtered from crystalline targets

    International Nuclear Information System (INIS)

    Shapiro, M.H.; Trovato, E.; Tombrello, T.A.

    2001-01-01

    Recently, V.I. Shulga and W. Eckstein (Nucl. Instr. and Meth. B 145 (1998) 492) investigated the depth of origin of atoms sputtered from random elemental targets using the Monte Carlo code TRIM.SP and the lattice code OKSANA. They found that the mean depth of origin is proportional to N -0.86 , where N is the atomic density; and that the most probable escape depth is ∼λ 0 /2, where λ 0 is the mean atomic distance. Since earlier molecular dynamics simulations with small crystalline elemental targets typically produced a most probable escape depth of zero (i.e., most sputtered atoms came from the topmost layer of the target), we have carried out new molecular dynamics simulations of sputtered atom escape depths with much larger crystalline targets. Our new results, which include the bcc targets Cs, Rb and W, as well as the fcc targets Cu and Au predict that the majority of sputtered atoms come from the first atomic layer for the bcc(1 0 0), bcc(1 1 1), fcc(1 0 0) and fcc(1 1 1) targets studied. For the high-atomic density targets Cu, Au and W, the mean depth of origin of sputtered atoms typically is less than 0.25λ 0 . For the low-atomic density targets Cs and Rb, the mean depth of origin of sputtered atoms is considerably larger, and depends strongly on the crystal orientation. We show that the discrepancy between the single-crystal and amorphous target depth of origin values can be resolved by applying a simple correction to the single-crystal results

  19. Molecular dynamics investigations of regioselectivity of anionic/aromatic substrates by a family of enzymes: a case study of diclofenac binding in CYP2C isoforms.

    Science.gov (United States)

    Cui, Ying-Lu; Xu, Fang; Wu, Rongling

    2016-06-29

    The CYP2C subfamily is of particular importance in the metabolism of drugs, food toxins, and procarcinogens. Like other P450 subfamilies, 2C enzymes share a high sequence identity, but significantly contribute in different ways to hepatic capacity to metabolize drugs. They often metabolize the same substrate to more than one product with different catalytic sites. Because it is challenging to characterize experimentally, much still remains unknown about the reason for why the substrate regioselectivity of these closely related subfamily members is different. Here, we have investigated the structural features of CYP2C8, CYP2C9, and CYP2C19 bound with their shared substrate diclofenac to elucidate the underlying molecular mechanism for the substrate regioselectivity of CYP2C subfamily enzymes. The obtained results demonstrate how a sequence divergence for the active site residues causes heterogeneous variations in the secondary structures and in major tunnel selections, and further affects the shape and chemical properties of the substrate-binding site. Structural analysis and free energy calculations showed that the most important determinants of regioselectivity among the CYP2C isoforms are the geometrical features of the active sites, as well as the hydrogen bonds and the hydrophobic interactions, mainly presenting as the various locations of Arg108 and substitutions of Phe205 for Ile205 in CYP2C8. The MM-GB/SA calculations combined with PMF results accord well with the experimental KM values, bridging the gap between the theory and the experimentally observed results of binding affinity differences. The present study provides important insights into the structure-function relationships of CYP2C subfamily enzymes, the knowledge of ligand binding characteristics and key residue contributions could guide future experimental and computational work on the synthesis of drugs with better pharmacokinetic properties so that CYP interactions could be avoided.

  20. Micropolarity and Hydrogen-Bond Donor Ability of Environmentally Friendly Anionic Reverse Micelles Explored by UV/Vis Absorption of a Molecular Probe and FTIR Spectroscopy.

    Science.gov (United States)

    Girardi, Valeria R; Silber, Juana J; Falcone, Ruben Darío; Correa, N Mariano

    2018-03-19

    In the present work we show how two biocompatible solvents, methyl laurate (ML) and isopropyl myristate (IPM), can be used as a less toxic alternative to replace the nonpolar component in a sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles (RMs) formulation. In this sense, the micropolarity and the hydrogen-bond ability of the interface were monitored through the use of the solvatochromism of a molecular probe (1-methyl-8-oxyquinolinium betaine, QB) and Fourier transform infrared spectroscopy (FTIR). Our results demonstrate that the micropolarity sensed by QB in ML RMs is lower than in IPM RMs. Additionally, the water molecules form stronger H-bond interactions with the polar head of AOT in ML than in IPM. By FTIR was revealed that more water molecules interact with the interface in ML/AOT RMs. On the other hand, for AOT RMs generated in IPM, the weaker water-surfactant interaction allows the water molecules to establish hydrogen bonds with each other trending to bulk water more easily than in ML RMs, a consequence of the dissimilar penetration of nonpolar solvents into the interfacial region. The penetration process is strongly controlled by the polarity and viscosity of the external solvents. All of these results allow us to characterize these biocompatible systems, providing information about interfacial properties and how they can be altered by changing the external solvent. The ability of the nontoxic solvent to penetrate or not into the AOT interface produces a new interface with attractive properties. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Study of the chemical sputtering in Tore-Supra

    International Nuclear Information System (INIS)

    Cambe, A.

    2002-01-01

    The work presented in this thesis focuses on the interactions between energetic particles coming from thermonuclear plasma and the inner components of a fusion machine. This interaction induces two major problems: erosion of the wall, and tritium retention. This report treats the erosion of carbon based materials. The first part is devoted to chemical sputtering, that appears to be the principal erosion mechanism, compared to physical sputtering and radiation enhanced sublimation that both can be limited. Chemical sputtering has been studied in situ in the tokamak Tore-Supra for ohmic and lower hybrid (LH) heated discharges, by means of mass spectrometry and optical spectroscopy. We have shown that it is necessary to take into account both methane and heavier hydrocarbons (C 2 D x and C 3 D y ) in the determination of the chemical sputtering yield. It is found that for the ohmic discharges, the sputtering yield of CD 4 (Y CD4 ) is highly flux (φ) dependent, showing a variation of the form: Y CD4 ∝ φ -0.23 . The experimental study also reveals that an increase of the surface temperature induces an augmentation of Y CD4 . The interpretation and the modelling of the experimental results have been performed with a Monte Carlo code (BBQ. In the second part of this work, we have developed and installed an infrared spectroscopy diagnostic in the 0.8-1.6, μm wavelength range dedicated to the measurement of surface temperature, and the identification of atomic and molecular lines emitted during plasma/wall interactions. In the third part, we present the feasibility study of an in situ tungsten deposition process at low temperature(<80 deg C) in order to suppress the chemical sputtering. This study shows that, with this method call Plasma Assisted Chemical Vapor Deposition (PACVD), we are able to coat the whole inner vessel of a tokamak with 1 μm of tungsten. (author)

  2. Co-sputtered optical films

    Energy Technology Data Exchange (ETDEWEB)

    Misiano, C; Simonetti, E [Selenia S.p.A., Rome (Italy)

    1977-06-01

    The co-sputtering of two dielectric materials with indices of refraction as widely different as possible has been investigated with the aim of obtaining both homogeneous films with an intermediate index of refraction and inhomogeneous films with predetermined profiles. An rf sputtering module is described which has been especially designed, with two separate cathodes and two independent tunable rf generators. The substrates are placed on a circular anode rotating underneath the two cathodes. So far mainly CeO/sub 2/, TiO2 and SiO/sub 2/ targets have been used. The deposition rate from each cathode and the total film thickness are determined by means of two quartz thickness monitors, sputtering compatible. Values obtained for the refractive index and optical thickness are reported, as well as repeatability, mechanical and chemical characteristics, reliability and high power optical radiation resistance. Finally, results obtained on optical components of practical interest are discussed.

  3. Laser sputter neutral mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    King, B V; Clarke, M; Hu, H; Betz, [Newcastle Univ., NSW (Australia). Dept. of Physics

    1994-12-31

    Laser sputter neutral mass spectrometry (LSNMS) is an emerging technique for highly sensitive surface analysis. In this technique a target is bombarded with a pulsed beam of keV ions. The sputtered particles are intercepted by a high intensity pulsed laser beam above the surface and ionised with almost 100% efficiency. The photions may then be mass analysed using a quadrupole or, more commonly, using time of flight (TOF) techniques. In this method photoions are extracted from the ionisation region, accelerated to a known energy E{sub o} and strike a channelplate detector a distance `d` away. The flight time `t` of the photoions is then related to their mass by `d` {radical}m / {radical} 2E{sub o} so measurement of `t` allows mass spectra to be obtained. It is found that LSNMS is an emerging technique of great sensitivity and flexibility, useful for both applied analysis and to investigate basic sputtering processes. 4 refs., 3 figs.

  4. Laser sputter neutral mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    King, B.V.; Clarke, M.; Hu, H.; Betz [Newcastle Univ., NSW (Australia). Dept. of Physics

    1993-12-31

    Laser sputter neutral mass spectrometry (LSNMS) is an emerging technique for highly sensitive surface analysis. In this technique a target is bombarded with a pulsed beam of keV ions. The sputtered particles are intercepted by a high intensity pulsed laser beam above the surface and ionised with almost 100% efficiency. The photions may then be mass analysed using a quadrupole or, more commonly, using time of flight (TOF) techniques. In this method photoions are extracted from the ionisation region, accelerated to a known energy E{sub o} and strike a channelplate detector a distance `d` away. The flight time `t` of the photoions is then related to their mass by `d` {radical}m / {radical} 2E{sub o} so measurement of `t` allows mass spectra to be obtained. It is found that LSNMS is an emerging technique of great sensitivity and flexibility, useful for both applied analysis and to investigate basic sputtering processes. 4 refs., 3 figs.

  5. Faraday screen sputtering on TPX

    International Nuclear Information System (INIS)

    Ehst, D.A.

    1994-12-01

    The TPX design stipulates that the ion-cyclotron resonance frequency (ICRF) antenna must have a Faraday screen (FS). The author considers here possible low Z coatings for the screen, as well as sputtering behavior of the Ni and Ti substrates. The theory of rf-induced sputtering has been developed, and he follows those theoretical approaches. The author's emphasis will be on both impurity generation as a possible source of increased Z eff , and also on actual erosion-lifetime of the materials under worst case conditions

  6. On niobium sputter coated cavities

    International Nuclear Information System (INIS)

    Arnolds-Mayer, G.; Kaufmann, U.; Downar, H.

    1988-01-01

    To coat copper cavities with a thin film of niobium, facilities for electropolishing and sputter deposition have been installed at Dornier. Experiments have been performed on samples to optimize electropolishing and deposition parameters. In this paper, characteristics concerning surface properties, adhesion of the niobium film to the copper substrate, and film properties were studied on planar samples. A 1.5 GHz single cell cavity made from oxygen free high conductivity (OFHC) copper was sputter coated twice. First rf measurements were performed in the temperature range from 300 K to 2 K

  7. Anionic surface binders

    OpenAIRE

    Aljaž-Rožič Mateja; Hočevar Nežka

    2004-01-01

    The MELAMIN Chemical Factory in Kočevje manufactures synthetic resins and binders for the paper industry. Binders based on AKD (alkyl ketene dimer) are produced which are used for binding paper and cardboard in the range of neutral and partially basic pH. Cationic and, lately, anionic binders are mostly used for the bulk binding of paper and board. The possibility of using AKD binders on paper or board surfaces is presented. In this case partially cationic AKD binders may be applied. When opt...

  8. Doubly charged ion emission in sputtering of monocrystalline fluorides

    Czech Academy of Sciences Publication Activity Database

    Lörinčík, Jan; Šroubek, Zdeněk

    2002-01-01

    Roč. 187, č. 4 (2002), s. 447-450 ISSN 0168-583X. [Atomic Collisions in Solids ICACS /19./. Paris, 29.07.2001-03.08.2001] R&D Projects: GA AV ČR IAA1067801; GA ČR GA202/99/0881 Institutional research plan: CEZ:AV0Z2067918 Keywords : sputtering * molecular electronic states * secondary ion emission Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.158, year: 2002

  9. Formation and stability of sputtered clusters

    International Nuclear Information System (INIS)

    Andersen, H.H.

    1989-01-01

    Current theory for the formation of sputtered clusters states that either atoms are sputtered individually and aggregate after having left the surface or they are sputtered as complete clusters. There is no totally sharp boundary between the two interpretations, but experimental evidence is mainly thought to favour the latter model. Both theories demand a criterion for the stability of the clusters. In computer simulations of sputtering, the idea has been to use the same interaction potential as in the lattice computations to judge the stability. More qualitatively, simple geometrical shapes have also been looked for. It is found here, that evidence for 'magic numbers' and electron parity effects in clusters have existed in the sputtering literature for a long time, making more sophisticated stability criteria necessary. The breakdown of originally sputtered metastable clusters into stable clusters gives strong support to the 'sputtered as clusters' hypothesis. (author)

  10. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Together with hydrotalcite-like layered double hydroxides, bivalent and trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange ...

  11. Crystal structure of an organic–inorganic supra­molecular salt based on a 4,4′-methyl­enebis(3,5-dimethyl-1H-pyrazol-2-ium) cation and a β-octa­molybdate anion

    Science.gov (United States)

    Amarante, Tatiana R.; Gonçalves, Isabel S.; Almeida Paz, Filipe A.

    2016-01-01

    The asymmetric unit of the title compound, bis­[4,4′-methyl­enebis(3,5-dimethyl-1H-pyrazol-2-ium)] β-octa­molybdate, (C11H18N4)2[Mo8O26] or (H4mbdpz)2[Mo8O26], is composed of an H4mbdpz2+ cation and half of the β-octa­molybdate anion which is completed by inversion symmetry. The organic mol­ecular units are engaged in a series of N—H⋯O hydrogen bonds with neighbouring anions, with N⋯O distances and N—H⋯O angles in the ranges 2.730 (2)–2.941 (2) Å and 122–166°, respectively. These inter­actions lead to the formation of a supra­molecular two-dimensional network parallel to the (010) plane. PMID:26958369

  12. Anion induced conformational preference of Cα NN motif residues in functional proteins.

    Science.gov (United States)

    Patra, Piya; Ghosh, Mahua; Banerjee, Raja; Chakrabarti, Jaydeb

    2017-12-01

    Among different ligand binding motifs, anion binding C α NN motif consisting of peptide backbone atoms of three consecutive residues are observed to be important for recognition of free anions, like sulphate or biphosphate and participate in different key functions. Here we study the interaction of sulphate and biphosphate with C α NN motif present in different proteins. Instead of total protein, a peptide fragment has been studied keeping C α NN motif flanked in between other residues. We use classical force field based molecular dynamics simulations to understand the stability of this motif. Our data indicate fluctuations in conformational preferences of the motif residues in absence of the anion. The anion gives stability to one of these conformations. However, the anion induced conformational preferences are highly sequence dependent and specific to the type of anion. In particular, the polar residues are more favourable compared to the other residues for recognising the anion. © 2017 Wiley Periodicals, Inc.

  13. Semi-empirical formulas for sputtering yield

    International Nuclear Information System (INIS)

    Yamamura, Yasumichi

    1994-01-01

    When charged particles, electrons, light and so on are irradiated on solid surfaces, the materials are lost from the surfaces, and this phenomenon is called sputtering. In order to understand sputtering phenomenon, the bond energy of atoms on surfaces, the energy given to the vicinity of surfaces and the process of converting the given energy to the energy for releasing atoms must be known. The theories of sputtering and the semi-empirical formulas for evaluating the dependence of sputtering yield on incident energy are explained. The mechanisms of sputtering are that due to collision cascade in the case of heavy ion incidence and that due to surface atom recoil in the case of light ion incidence. The formulas for the sputtering yield of low energy heavy ion sputtering, high energy light ion sputtering and the general case between these extreme cases, and the Matsunami formula are shown. At the stage of the publication of Atomic Data and Nuclear Data Tables in 1984, the data up to 1983 were collected, and about 30 papers published thereafter were added. The experimental data for low Z materials, for example Be, B and C and light ion sputtering data were reported. The combination of ions and target atoms in the collected sputtering data is shown. The new semi-empirical formula by slightly adjusting the Matsunami formula was decided. (K.I.)

  14. Perspective: Electrospray photoelectron spectroscopy: From multiply-charged anions to ultracold anions

    International Nuclear Information System (INIS)

    Wang, Lai-Sheng

    2015-01-01

    Electrospray ionization (ESI) has become an essential tool in chemical physics and physical chemistry for the production of novel molecular ions from solution samples for a variety of spectroscopic experiments. ESI was used to produce free multiply-charged anions (MCAs) for photoelectron spectroscopy (PES) in the late 1990 s, allowing many interesting properties of this class of exotic species to be investigated. Free MCAs are characterized by strong intramolecular Coulomb repulsions, which create a repulsive Coulomb barrier (RCB) for electron emission. The RCB endows many fascinating properties to MCAs, giving rise to meta-stable anions with negative electron binding energies. Recent development in the PES of MCAs includes photoelectron imaging to examine the influence of the RCB on the electron emission dynamics, pump-probe experiments to examine electron tunneling through the RCB, and isomer-specific experiments by coupling PES with ion mobility for biological MCAs. The development of a cryogenically cooled Paul trap has led to much better resolved PE spectra for MCAs by creating vibrationally cold anions from the room temperature ESI source. Recent advances in coupling the cryogenic Paul trap with PE imaging have allowed high-resolution PE spectra to be obtained for singly charged anions produced by ESI. In particular, the observation of dipole-bound excited states has made it possible to conduct vibrational autodetachment spectroscopy and resonant PES, which yield much richer vibrational spectroscopic information for dipolar free radicals than traditional PES

  15. Skeleton polyhedral rearrangements of 8-alkyl-7,9-dicarba-nido-undecaborate(-1) anion to 11-alkyl-2,7-dicarba-nido-undecaborane(13) and to 9-alkyl-7,8-dicarba-nido-undecaborate(-1) anion. Molecular structure of 2,7-Me2-11-PhCH2-2,7-C2B9H10

    International Nuclear Information System (INIS)

    Zakharkin, K.I.; Zhigareva, G.G.; Antonovich, V.A.; Yanovskij, A.I.; Struchkov, Yu.T.

    1986-01-01

    Using the methods of 1 H and 11 B NMR-spectroscopy and X-ray diffraction analysis skeleton polyhedral rearrangements of carboranes are studied. During protonation of anion 8-R-7, 9-R' 2 -7, 9-C 2 B 9 H 9 - the skeleton polyhedral rearrangement in the series of nido-carboranes, resulting in 2,7-R' 2 -11-R-2, 7-C 2 B 9 H 10 (R=Me, PhCH 2 , R'=H, Me) is observed. The rearrangement is reversible. On the detachment of two protons from 2,7-Me 2 -11-PhCH 2 -2,7-C 2 B 9 H 10 and during subsequent protonation the skeleton polyhedral rearrangement with the formation of anion 9-PhCH 2 -7,8-Me 2 -7,8-C 2 B 9 H 9 - takes place

  16. Probes for anionic cell surface detection

    Science.gov (United States)

    Smith, Bradley D.

    2013-03-05

    Embodiments of the present invention are generally directed to compositions comprising a class of molecular probes for detecting the presence of anionic cell surfaces. Embodiments include compositions that are enriched for these compositions and preparations, particularly preparations suitable for use as laboratory/clinical reagents and diagnostic indicators, either alone or as part of a kit. An embodiment of the invention provides for a highly selective agent useful in the discernment and identification of dead or dying cells, such as apoptotic cells, in a relatively calcium-free environment. An embodiment of the invention provides a selective agent for the identification of bacteria in a mixed population of bacterial cells and nonbacterial cells.

  17. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  18. Laser fluorescence spectroscopy of sputtered uranium atoms

    International Nuclear Information System (INIS)

    Wright, R.B.; Pellin, M.J.; Gruen, D.M.; Young, C.E.

    1979-01-01

    Laser induced fluorescence (LIF) spectroscopy was used to study the sputtering of 99.8% 238 U metal foil when bombarded by normally incident 500 to 3000 eV Ne + , Ar + , Kr + , and O 2 + . A three-level atom model of the LIF processes is developed to interpret the observed fluorescent emission from the sputtered species. The model shows that close attention must be paid to the conditions under which the experiment is carried out as well as to the details of the collision cascade theory of sputtering. Rigorous analysis shows that when properly applied, LIF can be used to investigate the predictions of sputtering theory as regards energy distributions of sputtered particles and for the determination of sputtering yields. The possibility that thermal emission may occur during sputtering can also be tested using the proposed model. It is shown that the velocity distribution (either the number density or flux density distribution, depending upon the experimental conditions) of the sputtered particles can be determined using the LIF technique and that this information can be used to obtain a description of the basic sputtering mechanisms. These matters are discussed using the U-atom fluorescence measurements as a basis. The relative sputtering yields for various incident ions on uranium were also measured for the first time using the LIF technique. A surprisingly high fraction of the sputtered uranium atoms were found to occupy the low lying metastable energy levels of U(I). The population of the sputtered metastable atoms were found approximately to obey a Boltzman distribution with an effective temperature of 920 +- 100 0 K. 41 references

  19. Simulation experiments and solar wind sputtering

    International Nuclear Information System (INIS)

    Griffith, J.E.; Papanastassiou, D.A.; Russell, W.A.; Tombrello, T.A.; Weller, R.A.

    1978-01-01

    In order to isolate the role played by solar wind sputtering from other lunar surface phenomena a number of simulation experiments were performed, including isotope abundance measurements of Ca sputtered from terrestrial fluorite and plagioclase by 50-keV and 130-keV 14 N beams, measurement of the energy distribution of U atoms sputtered with 80-keV 40 Ar, and measurement of the fraction of sputtered U atoms which stick on the surfaces used to collect these atoms. 10 references

  20. Reduction of residual gas in a sputtering system by auxiliary sputter of rare-earth metal

    International Nuclear Information System (INIS)

    Li Dejie

    2002-01-01

    In film deposition by sputtering, the oxidation and nitrification of the sputtered material lead to degradation of film quality, particularly with respect to metal sulfide films. We propose to use auxiliary sputtering as a method to produce a fresh film of rare-earth metal, usually dysprosium (Dy), that absorbs the active gases in a sputtering system, greatly reducing the background pressure and protecting the film from oxidation and nitrification effectively. The influence of the auxiliary sputtering power consumption, sputtering time, and medium gas pressure on the background pressure in the vacuum chamber is investigated in detail. If the auxiliary sputtering power exceeds 120 W and the sputtering time is more than 4 min, the background pressure is only one fourth of the ultimate pressure pumped by an oil diffusion pump. The absorption activity of the sputtered Dy film continues at least an hour after completion of the auxiliary sputter. Applied to film deposition of Ti and ZnS, this technique has been proven to be effective. For the Ti film, the total content of N and O is reduced from 45% to 20% when the auxiliary sputtering power of Dy is 120 W, and the sputtering time is 20 min. In the case of ZnS, the content of O is reduced from 8% to 2%

  1. Simultaneous anionic and cationic redox

    Science.gov (United States)

    Jung, Sung-Kyun; Kang, Kisuk

    2017-12-01

    It is challenging to unlock anionic redox activity, accompanied by full utilization of available cationic redox process, to boost capacity of battery cathodes. Now, material design by tuning the metal-oxygen interaction is shown to be a promising solution.

  2. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar; Zhao, Junpeng; Zhang, Hefeng; Hadjichristidis, Nikolaos; Mays, Jimmy

    2015-01-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands

  3. Benzonitrile: Electron affinity, excited states, and anion solvation

    Science.gov (United States)

    Dixon, Andrew R.; Khuseynov, Dmitry; Sanov, Andrei

    2015-10-01

    We report a negative-ion photoelectron imaging study of benzonitrile and several of its hydrated, oxygenated, and homo-molecularly solvated cluster anions. The photodetachment from the unsolvated benzonitrile anion to the X ˜ 1 A 1 state of the neutral peaks at 58 ± 5 meV. This value is assigned as the vertical detachment energy (VDE) of the valence anion and the upper bound of adiabatic electron affinity (EA) of benzonitrile. The EA of the lowest excited electronic state of benzonitrile, a ˜ 3 A 1 , is determined as 3.41 ± 0.01 eV, corresponding to a 3.35 eV lower bound for the singlet-triplet splitting. The next excited state, the open-shell singlet A ˜ 1 A 1 , is found about an electron-volt above the triplet, with a VDE of 4.45 ± 0.01 eV. These results are in good agreement with ab initio calculations for neutral benzonitrile and its valence anion but do not preclude the existence of a dipole-bound state of similar energy and geometry. The step-wise and cumulative solvation energies of benzonitrile anions by several types of species were determined, including homo-molecular solvation by benzonitrile, hydration by 1-3 waters, oxygenation by 1-3 oxygen molecules, and mixed solvation by various combinations of O2, H2O, and benzonitrile. The plausible structures of the dimer anion of benzonitrile were examined using density functional theory and compared to the experimental observations. It is predicted that the dimer anion favors a stacked geometry capitalizing on the π-π interactions between the two partially charged benzonitrile moieties.

  4. Sputtering of copper (110) by 3 keV argon - a computer simulation

    International Nuclear Information System (INIS)

    Weygandt, A.; King, B.V.

    1998-01-01

    The aims of this study are to investigate the angular distribution of atoms sputtered from {110} surface of a copper monocrystal due to normal incidence 3 keV Argon impact as well as to examine the change of sputtering behaviour with temperature from 0 K to 670 K. We have used the Molecular Dynamics (MD) code SPUT93 to study sputtering. In MD codes Newton's equations of motion are solved simultanously for all atoms of a crystal. The forces acting on a particle are found from derivatives of a model potential function. For the present study an embedded atom method (EAM) potential was used. It was found that the total sputter yield for the warm crystal (670K) of 3.13 ± 0.03 is in agreement with experimental results and indicate that the temperature of the target has generally no direct influence on the sputtering yield. It was estimated that heating the crystal only causes more uniform emission. It was also found that ejection due to the collisions between atoms in the top layers along closed-packed directions become important. The mechanisms which determine the angular distributions of atoms sputtered from a copper crystal were identified

  5. Effect of sputtering power on structure and properties of Bi film deposited by DC magnetron sputtering

    International Nuclear Information System (INIS)

    Liao Guo; He Zhibing; Xu Hua; Li Jun; Chen Taihua; Chen Jiajun

    2012-01-01

    Bi film was fabricated at different sputtering powers by DC magnetron sputtering. The deposition rate of Bi film as the function of sputtering power was studied. The surface topography of Bi film was observed by SEM, and the growth mode of Bi film was investigated. The crystal structure was analyzed by XRD. The grain size and stress of Bi film were calculated. The SEM images show that all the films are columnar growth. The average grain size firstly increases as the sputtering power increases, then decreases at 60 W. The film becomes loose with the increase of sputtering power, while, the film gets compact when the sputtering power becomes from 45 to 60 W. The XRD results show that films are polycrystalline of hexagonal. And the stress transforms from the tensile stress to compressive stress as the sputtering power increases. (authors)

  6. Molecules for materials: germanium hydride neutrals and anions. Molecular structures, electron affinities, and thermochemistry of GeHn/GeHn- (n = 0-4) and Ge2Hn/Ge2Hn(-) (n = 0-6).

    Science.gov (United States)

    Li, Qian-Shu; Lü, Rui-Hua; Xie, Yaoming; Schaefer, Henry F

    2002-12-01

    The GeH(n) (n = 0-4) and Ge(2)H(n) (n = 0-6) systems have been studied systematically by five different density functional methods. The basis sets employed are of double-zeta plus polarization quality with additional s- and p-type diffuse functions, labeled DZP++. For each compound plausible energetically low-lying structures were optimized. The methods used have been calibrated against a comprehensive tabulation of experimental electron affinities (Chemical Reviews 102, 231, 2002). The geometries predicted in this work include yet unknown anionic species, such as Ge(2)H(-), Ge(2)H(2)(-), Ge(2)H(3)(-), Ge(2)H(4)(-), and Ge(2)H(5)(-). In general, the BHLYP method predicts the geometries closest to the few available experimental structures. A number of structures rather different from the analogous well-characterized hydrocarbon radicals and anions are predicted. For example, a vinylidene-like GeGeH(2) (-) structure is the global minimum of Ge(2)H(2) (-). For neutral Ge(2)H(4), a methylcarbene-like HGë-GeH(3) is neally degenerate with the trans-bent H(2)Ge=GeH(2) structure. For the Ge(2)H(4) (-) anion, the methylcarbene-like system is the global minimum. The three different neutral-anion energy differences reported in this research are: the adiabatic electron affinity (EA(ad)), the vertical electron affinity (EA(vert)), and the vertical detachment energy (VDE). For this family of molecules the B3LYP method appears to predict the most reliable electron affinities. The adiabatic electron affinities after the ZPVE correction are predicted to be 2.02 (Ge(2)), 2.05 (Ge(2)H), 1.25 (Ge(2)H(2)), 2.09 (Ge(2)H(3)), 1.71 (Ge(2)H(4)), 2.17 (Ge(2)H(5)), and -0.02 (Ge(2)H(6)) eV. We also reported the dissociation energies for the GeH(n) (n = 1-4) and Ge(2)H(n) (n = 1-6) systems, as well as those for their anionic counterparts. Our theoretical predictions provide strong motivation for the further experimental study of these important germanium hydrides. Copyright 2002 Wiley

  7. Structure and dynamics of solvated hydrogenoxalate and oxalate anions: theoretical study

    Czech Academy of Sciences Publication Activity Database

    Kroutil, O.; Minofar, Babak; Kabeláč, M.

    2016-01-01

    Roč. 22, č. 9 (2016), s. 210 ISSN 1610-2940 Institutional support: RVO:61388971 Keywords : Ab initio molecular dynamics * oxalic acid anions * Potential energy surface Subject RIV: EE - Microbiology, Virology Impact factor: 1.425, year: 2016

  8. Introducing various ligands into superhalogen anions reduces their electronic stabilities

    Science.gov (United States)

    Smuczyńska, Sylwia; Skurski, Piotr

    2008-02-01

    The vertical electron detachment energies (VDE) of six NaX2- anions (where X = F, Cl, Br) were calculated at the OVGF level with the 6-311++G(3df) basis sets. In all the cases studied the VDE exceeds the electron affinity of chlorine atom and thus those species were classified as superhalogen anions. The largest vertical binding energy was found for the NaF2- system (6.644 eV). The strong VDE dependence on the ligand type, ligand-central atom distance, and the character of the highest occupied molecular orbital (HOMO) was observed and discussed.

  9. Sputtering calculations with the discrete ordinated method

    International Nuclear Information System (INIS)

    Hoffman, T.J.; Dodds, H.L. Jr.; Robinson, M.T.; Holmes, D.K.

    1977-01-01

    The purpose of this work is to investigate the applicability of the discrete ordinates (S/sub N/) method to light ion sputtering problems. In particular, the neutral particle discrete ordinates computer code, ANISN, was used to calculate sputtering yields. No modifications to this code were necessary to treat charged particle transport. However, a cross section processing code was written for the generation of multigroup cross sections; these cross sections include a modification to the total macroscopic cross section to account for electronic interactions and small-scattering-angle elastic interactions. The discrete ordinates approach enables calculation of the sputtering yield as functions of incident energy and angle and of many related quantities such as ion reflection coefficients, angular and energy distributions of sputtering particles, the behavior of beams penetrating thin foils, etc. The results of several sputtering problems as calculated with ANISN are presented

  10. Chemical sputtering of graphite by H+ ions

    International Nuclear Information System (INIS)

    Busharov, N.P.; Gorbatov, E.A.; Gusev, V.M.; Guseva, M.I.; Martynenko, Y.V.

    1976-01-01

    In a study of the sputtering coefficient S for the sputtering of graphite by 10-keV H + ions as a function of the graphite temperature during the bombardment, it is found that at T> or =750degreeC the coefficient S is independent of the target temperature and has an anomalously high value, S=0.085 atom/ion. The high rate of sputtering of graphite by atomic hydrogen ions is shown to be due to chemical sputtering of the graphite, resulting primarily in the formation of CH 4 molecules. At T=1100degreeC, S falls off by a factor of about 3. A model for the chemical sputtering of graphite is proposed

  11. Novel magnetic controlled plasma sputtering method

    International Nuclear Information System (INIS)

    Axelevich, A.; Rabinovich, E.; Golan, G.

    1996-01-01

    A novel method to improve thin film vacuum sputtering is presented. This method is capable of controlling the sputtering plasma via an external set of magnets, in a similar fashion to the tetrode sputtering method. The main advantage of the Magnetic Controlled Plasma Sputtering (MCPS) is its ability to independently control all deposition parameters without any interference or cross-talk. Deposition rate, using the MCPS, is found to be almost twice the rate of triode and tetrode sputtering techniques. Experimental results using the MCPS to deposit Ni layers are described. It was demonstrated that using the MCPS method the ion beam intensity at the target is a result of the interaction of a homogeneous external magnetic field and the controlling magnetic fields. The MCPS method was therefore found to be beneficial for the production of pure stoichiometric thin solid films with high reproducibility. This method could be used for the production of compound thin films as well. (authors)

  12. Low-Damage Sputter Deposition on Graphene

    Science.gov (United States)

    Chen, Ching-Tzu; Casu, Emanuele; Gajek, Marcin; Raoux, Simone

    2013-03-01

    Despite its versatility and prevalence in the microelectronics industry, sputter deposition has seen very limited applications for graphene-based electronics. We have systematically investigated the sputtering induced graphene defects and identified the reflected high-energy neutrals of the sputtering gas as the primary cause of damage. In this talk, we introduce a novel sputtering technique that is shown to dramatically reduce bombardment of the fast neutrals and improve the structural integrity of the underlying graphene layer. We also demonstrate that sputter deposition and in-situ oxidation of 1 nm Al film at elevated temperatures yields homogeneous, fully covered oxide films with r.m.s. roughness much less than 1 monolayer, which shows the potential of using such technique for gate oxides, tunnel barriers, and multilayer fabrication in a wide range of graphene devices.

  13. Measurements of beryllium sputtering yields at JET

    Science.gov (United States)

    Jet-Efda Contributors Stamp, M. F.; Krieger, K.; Brezinsek, S.

    2011-08-01

    The lifetime of the beryllium first wall in ITER will depend on erosion and redeposition processes. The physical sputtering yields for beryllium (both deuterium on beryllium (Be) and Be on Be) are of crucial importance since they drive the erosion process. Literature values of experimental sputtering yields show an order of magnitude variation so predictive modelling of ITER wall lifetimes has large uncertainty. We have reviewed the old beryllium yield experiments on JET and used current beryllium atomic data to produce revised beryllium sputtering yields. These experimental measurements have been compared with a simple physical sputtering model based on TRIM.SP beryllium yield data. Fair agreement is seen for beryllium yields from a clean beryllium limiter. However the yield on a beryllium divertor tile (with C/Be co-deposits) shows poor agreement at low electron temperatures indicating that the effect of the higher sputtering threshold for beryllium carbide is important.

  14. Reactivity of niobium cluster anions with nitrogen and carbon monoxide

    Science.gov (United States)

    Mwakapumba, Joseph; Ervin, Kent M.

    1997-02-01

    Reactions of small niobium cluster anions, Nbn-(n = 2-7), with CO and N2 are investigated using a flow tube reactor (flowing afterglow) apparatus. Carbon monoxide chemisorption on niobium cluster anions occurs with faster reaction rates than nitrogen chemisorption on corresponding cluster sizes. N2 addition to niobium cluster anions is much more size-selective than is CO addition. These general trends follow those reported in the literature for reactions of neutral and cationic niobium clusters with CO and N2. Extensive fragmentation of the clusters is observed upon chemisorption. A small fraction of the larger clusters survive and sequentially add multiple CO or N2 units without fragmentation. However, chemisorption saturation is not reached at the experimentally accessible pressure and reagent concentration ranges. The thermochemistry of the adsorption processes and the nature of the adsorbed species, molecular or dissociated, are discussed.

  15. Carbon dust formation in a cold plasma from cathode sputtering

    International Nuclear Information System (INIS)

    Arnas, C.; Mouberi, A.; Hassouni, K.; Michau, A.; Lombardi, G.; Bonnin, X.; Benedic, F.; Pegourie, B.

    2009-01-01

    Nanoparticles are produced in argon glow plasmas where carbon is introduced by sputtering of a graphite cathode. A scaling law of growth is reported on as a function of the discharge time. Two successive stages of growth of concomitant agglomeration and carbon deposition are observed, followed by a final stage of growth by carbon deposition. A model of formation of molecular precursors by coagulation of neutral clusters on the one hand and of neutral-negative clusters on the other hand is presented, based on formation enthalpy and cluster geometry.

  16. Carbon dust formation in a cold plasma from cathode sputtering

    Science.gov (United States)

    Arnas, C.; Mouberi, A.; Hassouni, K.; Michau, A.; Lombardi, G.; Bonnin, X.; Bénédic, F.; Pégourié, B.

    2009-06-01

    Nanoparticles are produced in argon glow plasmas where carbon is introduced by sputtering of a graphite cathode. A scaling law of growth is reported on as a function of the discharge time. Two successive stages of growth of concomitant agglomeration and carbon deposition are observed, followed by a final stage of growth by carbon deposition. A model of formation of molecular precursors by coagulation of neutral clusters on the one hand and of neutral-negative clusters on the other hand is presented, based on formation enthalpy and cluster geometry.

  17. Properties of RF magnetron sputtered gallium nitride semiconductors doped with erbium

    Czech Academy of Sciences Publication Activity Database

    Peřina, Vratislav; Macková, Anna; Hnatowicz, Vladimír; Prajzler, V.; Machovič, V.; Matějka, P.; Schröfel, J.

    2004-01-01

    Roč. 36, č. 8 (2004), s. 952-954 ISSN 0142-2421 R&D Projects: GA ČR GA104/03/0387 Institutional research plan: CEZ:AV0Z1048901 Keywords : Er-doped GaN * luminescence * magnetron sputtering Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.209, year: 2004

  18. High-power sputtering employed for film deposition

    International Nuclear Information System (INIS)

    Shapovalov, V I

    2017-01-01

    The features of high-power magnetron sputtering employed for the films’ deposition are reviewed. The main physical phenomena accompanying high-power sputtering including ion-electron emission, gas rarefaction, ionization of sputtered atoms, self-sputtering, ion sound waves and the impact of the target heating are described. (paper)

  19. REACTIVITY OF ANIONS IN INTERSTELLAR MEDIA: DETECTABILITY AND APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Senent, M. L. [Departamento de Quimica y Fisica Teoricas, Instituto de Estructura de la Materia, IEM-C.S.I.C., Serrano 121, Madrid E-28006 (Spain); Hochlaf, M., E-mail: senent@iem.cfmac.csic.es, E-mail: hochlaf@univ-mlv.fr [Laboratoire de Modelisation et Simulation Multi Echelle, Universite Paris-Est, MSME UMR 8208 CNRS, 5 boulevard Descartes, F-77454 Marne-la-Vallee (France)

    2013-05-01

    We propose a general rule to distinguish between detectable and undetectable astronomical anions. We believe that only few anions live long enough in the interstellar medium and thus can be detected. Our method is based on quantum mechanical calculations capable of describing accurately the evolution of electronic states during chemical processes. The still not fully understood reactivity at low temperatures is discussed considering non-adiabatic effects. The role of excited states has usually been neglected in previous works which basically focused on the ground electronic state for interpretations of experimental observations. Here, we deal with unsaturated carbon chains (e.g., C{sub n} H{sup -}), which show a high density of electronic states close to their corresponding ground electronic states, complex molecular dynamics, and non-adiabatic phenomena. Our general rule shows that it is not sufficient that anions exist in the gas phase (in the laboratory) to be present in media such as astrophysical media, since formation and decomposition reactions of these anions may allow the population of anionic electronic states to autodetach, forming neutrals. For C{sub n} H, reactivity depends strongly on n, where long and short chains behave differently. Formation of linear chains is relevant.

  20. Ion beam sputter implantation method

    International Nuclear Information System (INIS)

    King, W.J.

    1978-01-01

    By means of ion beam atomizing or sputtering an integrally composed coating, the composition of which continuously changes from 100% of the substrate to 100% of the coating, can be surfaced on a substrate (e.g. molten quartz on plastic lenses). In order to do this in the facility there is directed a primary beam of accelerated noble gas ions on a target from the group of the following materials: SiO 2 , Al 2 O 3 , Corning Glass 7070, Corning Glass 7740 or borosilicate glass. The particles leaving the target are directed on the substrate by means of an acceleration potential of up to 10 KV. There may, however, be coated also metal layers (Ni, Co) on a mylar film resulting in a semireflecting metal film. (RW) [de

  1. Implantation, recoil implantation, and sputtering

    International Nuclear Information System (INIS)

    Kelly, R.

    1984-01-01

    Underlying ion-beam modification of surfaces is the more basic subject of particle-surface interaction. The ideas can be grouped into forward and backward features, i.e. those affecting the interior of the target and those leading to particle expulsion. Forward effects include the stopping of the incident particles and the deposition of energy, both governed by integral equations which are easily set up but difficult to solve. Closely related is recoil implantation where emphasis is placed not on the stopping of the incident particles but on their interaction with target atoms with resulting implantation of these atoms. Backward effects, all of which are denoted as sputtering, are in general either of collisional, thermal, electronic, or exfoliational origin. (Auth.)

  2. Effects of ion sputtering on semiconductor surfaces

    International Nuclear Information System (INIS)

    McGuire, G.E.

    1978-01-01

    Ion beam sputtering has been combined with Auger spectroscopy to study the effects of ion beams on semiconductor surfaces. Observations on the mass dependence of ion selective sputtering of two component systems are presented. The effects of ion implantation are explained in terms of atomic dilution. Experimental data are presented that illustrate the super-position of selective sputtering and implantation effects on the surface composition. Sample reduction from electron and ion beam interaction is illustrated. Apparent sample changes which one might observe from the effects of residual gas contamination and electric fields are also discussed. (Auth.)

  3. Sensitivity and stability of sputtered sandwich photocells

    International Nuclear Information System (INIS)

    Murray, H.; Piel, A.

    1979-01-01

    The physical parameters of sputtered Metal-Semiconductor-Metal photocells are described in view of solar energy conversion. Specific properties of sputtered films lead to a particular stability of physical parameters such as dark conduction, capacitance and dielectric losses. Interband transitions occur when the photon energy is larger than the bandgap of the photoconductor. The transport of photo-excited carriers in the built-in electric field involves the existence of a photovoltaic effect. The influence of sputtering on the specific properties of solar energy conversion is discussed. (author)

  4. Modeling and analysis of surface roughness effects on sputtering, reflection, and sputtered particle transport

    International Nuclear Information System (INIS)

    Brooks, J.N.; Ruzic, D.N.

    1990-01-01

    The microstructure of the redeposited surface in tokamaks may affect sputtering and reflection properties and subsequent particle transport. This subject has been studied numerically using coupled models/codes for near-surface plasma particle kinetic transport (WBC code) and rough surface sputtering (fractal-TRIM). The coupled codes provide an overall Monte Carlo calculation of the sputtering cascade resulting from an initial flux of hydrogen ions. Beryllium, carbon, and tungsten surfaces are analyzed for typical high recycling, oblique magnetic field, divertor conditions. Significant variations in computed sputtering rates are found with surface roughness. Beryllium exhibits high D-T and self-sputtering coefficients for the plasma regime studied (T e = 30-75 eV). Carbon and tungsten sputtering is significantly lower. 9 refs., 6 figs., 1 tab

  5. Hybrid molecular materials based upon organic pi-electron donors and inorganic metal complexes. Conducting salts of bis(ethylenediseleno)tetrathiafulvalene (BEST) with the octahedral anions hexacyanoferrate(III) and nitroprusside

    CERN Document Server

    Clemente-Leon, M; Galan-Mascaros, J R; Giménez-Saiz, C; Gómez-García, C J; Fabre, J M; Mousdis, G A; Papavassiliou, G C

    2002-01-01

    The synthesis, structure and physical characterization of three new radical salts formed by the organic donor bis(ethylenediseleno)tetrathiafulvalene (BEDS-TTF or BEST) and the paramagnetic hexacyanoferrate(III) anion [Fe(CN) sub 6] sup 3 sup - or the photochromic nitroprusside anion [Fe(CN) sub 5 NO] sup 2 sup - are reported: (BEST) sub 4 [Fe(CN) sub 6] (1), (BEST) sub 3 [Fe(CN) sub 6] sub 2 centre dot H sub 2 O (2) and (BEST) sub 2 [Fe(CN) sub 5 NO] (3). Salts 1 and 3 show a layered structure with alternating organic (beta-type packing) and inorganic slabs. Salt 2 shows an original interpenetrated structure probably due to the unprecedented presence of (BEST) sup 2 sup + dications. The three salts are semiconductors although salt 1 exhibits a high room temperature conductivity and a semiconducting-semiconducting transition at ca. 150 K which has been attributed to a dimerization in the organic sublattice.

  6. A computational study of anion-modulated cation-π interactions.

    Science.gov (United States)

    Carrazana-García, Jorge A; Rodríguez-Otero, Jesús; Cabaleiro-Lago, Enrique M

    2012-05-24

    The interaction of anions with cation-π complexes formed by the guanidinium cation and benzene was thoroughly studied by means of computational methods. Potential energy surface scans were performed in order to evaluate the effect of the anion coming closer to the cation-π pair. Several structures of guanidinium-benzene complexes and anion approaching directions were examined. Supermolecule calculations were performed on ternary complexes formed by guanidinium, benzene, and one anion and the interaction energy was decomposed into its different two- and three-body contributions. The interaction energies were further dissected into their electrostatic, exchange, repulsion, polarization and dispersion contributions by means of local molecular orbital energy decomposition analysis. The results confirm that, besides the electrostatic cation-anion attraction, the effect of the anion over the cation-π interaction is mainly due to polarization and can be rationalized following the changes in the anion-π and the nonadditive (three-body) terms of the interaction. When the cation and the anion are on the same side of the π system, the three-body interaction is anticooperative, but when the anion and the cation are on opposite sides of the π system, the three-body interaction is cooperative. As far as we know, this is the first study where this kind of analysis is carried out with a structured cation as guanidinium with a significant biological interest.

  7. Pu Anion Exchange Process Intensification

    International Nuclear Information System (INIS)

    Taylor-Pashow, Kathryn M. L.

    2017-01-01

    This research is focused on improving the efficiency of the anion exchange process for purifying plutonium. While initially focused on plutonium, the technology could also be applied to other ion-exchange processes. Work in FY17 focused on the improvement and optimization of porous foam columns that were initially developed in FY16. These foam columns were surface functionalized with poly(4-vinylpyridine) (PVP) to provide the Pu specific anion-exchange sites. Two different polymerization methods were explored for maximizing the surface functionalization with the PVP. The open-celled polymeric foams have large open pores and large surface areas available for sorption. The fluid passes through the large open pores of this material, allowing convection to be the dominant mechanism by which mass transport takes place. These materials generally have very low densities, open-celled structures with high cell interconnectivity, small cell sizes, uniform cell size distributions, and high structural integrity. These porous foam columns provide advantages over the typical porous resin beads by eliminating the slow diffusion through resin beads, making the anion-exchange sites easily accessible on the foam surfaces. The best performing samples exceeded the Pu capacity of the commercially available resin, and also offered the advantage of sharper elution profiles, resulting in a more concentrated product, with less loss of material to the dilute heads and tails cuts. An alternate approach to improving the efficiency of this process was also explored through the development of a microchannel array system for performing the anion exchange.

  8. Ionic liquids comprising heteraromatic anions

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, William F.; Brennecke, Joan F.; Maginn, Edward J.; Mindrup, Elaine; Gurkan, Burcu; Price, Erica; Goodrich, Brett

    2018-04-24

    Some embodiments described herein relate to ionic liquids comprising an anion of a heteraromatic compound such as optionally substituted pyrrolide, optionally substituted pyrazolide, optionally substituted indolide, optionally substituted phospholide, or optionally substituted imidazolide. Methods and devices for gas separation or gas absorption related to these ionic liquids are also described herein.

  9. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Pashow, Kathryn M. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-10-06

    This research is focused on improving the efficiency of the anion exchange process for purifying plutonium. While initially focused on plutonium, the technology could also be applied to other ion-exchange processes. Work in FY17 focused on the improvement and optimization of porous foam columns that were initially developed in FY16. These foam columns were surface functionalized with poly(4-vinylpyridine) (PVP) to provide the Pu specific anion-exchange sites. Two different polymerization methods were explored for maximizing the surface functionalization with the PVP. The open-celled polymeric foams have large open pores and large surface areas available for sorption. The fluid passes through the large open pores of this material, allowing convection to be the dominant mechanism by which mass transport takes place. These materials generally have very low densities, open-celled structures with high cell interconnectivity, small cell sizes, uniform cell size distributions, and high structural integrity. These porous foam columns provide advantages over the typical porous resin beads by eliminating the slow diffusion through resin beads, making the anion-exchange sites easily accessible on the foam surfaces. The best performing samples exceeded the Pu capacity of the commercially available resin, and also offered the advantage of sharper elution profiles, resulting in a more concentrated product, with less loss of material to the dilute heads and tails cuts. An alternate approach to improving the efficiency of this process was also explored through the development of a microchannel array system for performing the anion exchange.

  10. IMPROVING OF ANION EXCHANGERES REGENERATION

    Directory of Open Access Journals (Sweden)

    Muzher M. Ibrahim

    2013-05-01

    Full Text Available Inthis study, Different basis [NaOH and KOH] of variable concentration are usedto reactivate Anion exchangers employing different schemes .The Laboratoryresults showed large improvement in efficiency of these exchangers ( i.eoperating time was increased from 12 to 42 hours .The results of this work showed that the environmentalload (waste water can be reduced greatly when using the proposed regenerationscheme .

  11. Quantum mechanics of toroidal anions

    International Nuclear Information System (INIS)

    Afanas'ev, G.N.

    1990-01-01

    We consider a toroidal solenoid with an electric charge attached to it. It turns out that statistical properties of the wave function describing interacting toroidal anions depend on both their relative position and orientation. The influence of the particular gauge choice on the exchange properties of the wave function is studied. 30 refs.; 6 figs

  12. Anion binding in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Feiters, Martin C [Department of Organic Chemistry, Institute for Molecules and Materials, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Meyer-Klaucke, Wolfram [EMBL Hamburg Outstation at DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Kostenko, Alexander V; Soldatov, Alexander V [Faculty of Physics, Southern Federal University, Sorge 5, Rostov-na-Donu, 344090 (Russian Federation); Leblanc, Catherine; Michel, Gurvan; Potin, Philippe [Centre National de la Recherche Scientifique and Universite Pierre et Marie Curie Paris-VI, Station Biologique de Roscoff, Place Georges Teissier, BP 74, F-29682 Roscoff cedex, Bretagne (France); Kuepper, Frithjof C [Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll PA37 1QA, Scotland (United Kingdom); Hollenstein, Kaspar; Locher, Kaspar P [Institute of Molecular Biology and Biophysics, ETH Zuerich, Schafmattstrasse 20, Zuerich, 8093 (Switzerland); Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R, E-mail: m.feiters@science.ru.n [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands)

    2009-11-15

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L{sub 3} (2p{sub 3/2}) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  13. Anion binding in biological systems

    International Nuclear Information System (INIS)

    Feiters, Martin C; Meyer-Klaucke, Wolfram; Kostenko, Alexander V; Soldatov, Alexander V; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Kuepper, Frithjof C; Hollenstein, Kaspar; Locher, Kaspar P; Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R

    2009-01-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L 3 (2p 3/2 ) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  14. Anion binding in biological systems

    Science.gov (United States)

    Feiters, Martin C.; Meyer-Klaucke, Wolfram; Kostenko, Alexander V.; Soldatov, Alexander V.; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Küpper, Frithjof C.; Hollenstein, Kaspar; Locher, Kaspar P.; Bevers, Loes E.; Hagedoorn, Peter-Leon; Hagen, Wilfred R.

    2009-11-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L3 (2p3/2) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  15. The Kansas State University revolving sputter source

    International Nuclear Information System (INIS)

    Tipping, T.N.

    1989-01-01

    It has been that the perfect ion source is one which runs in a very stable mode, runs continuously, and has the ability to change ion species without sacrificing the previous two requirements. This paper presents an approximation to the perfect ion source, the KSU Revolving Sputter Source. The source consists of an Aarhus-geometry sputter source with the addition of a rotating wheel which holds eight sputter cathodes. The wheel consists of a front plate with eight fixed Macor insulators and a back plate with eight Macor insulators held in place by the tension of eight springs. The cathode assembly consists of a copper cartridge with a threaded rod on one end and a sputter cathode with a threaded hole on the back. The cathode is screwed onto the cartridge and the whole assembly may be loaded into the wheel. A small spring on the side of the cartridge holds the assembly in the wheel

  16. Electrical resistivity of sputtered molybdenum films

    International Nuclear Information System (INIS)

    Nagano, J.

    1980-01-01

    The electrical resistivity of r.f. sputtered molybdenum films of thickness 5-150 nm deposited on oxidized silicon substrates was resolved into the three electron scattering components: isotropic background scattering, scattering at grain boundaries and scattering at surfaces. It was concluded that the isotropic background scattering is almost equal to that of bulk molybdenum and is not influenced by sputtering and annealing conditions. When the film thickness is sufficient that surface scattering can be ignored, the decrease in film resistivity after annealing is caused by the decrease in scattering at the grain boundaries for zero bias sputtered films, and is caused by an increase of the grain diameter for r.f. bias sputtered films. (Auth.)

  17. Large Area Sputter Coating on Glass

    Science.gov (United States)

    Katayama, Yoshihito

    Large glass has been used for commercial buildings, housings and vehicles for many years. Glass size for flat displays is getting larger and larger. The glass for the 8th generation is more than 5 m2 in area. Demand of the large glass is increasing not only in these markets but also in a solar cell market growing drastically. Therefore, large area coating is demanded to plus something else on glass more than ever. Sputtering and pyrolysis are the major coating methods on large glass today. Sputtering process is particularly popular because it can deposit a wide variety of materials in good coating uniformity on the glass. This paper describes typical industrial sputtering system and recent progress in sputtering technology. It also shows typical coated glass products in architectural, automotive and display fields and comments on their functions, film stacks and so on.

  18. Tripodal receptors for cation and anion sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman, [Unknown; Verboom, Willem; Reinhoudt, David

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing

  19. Observation of self-sputtering in energetic condensation of metal ions

    International Nuclear Information System (INIS)

    Anders, Andre

    2004-01-01

    The condensation of energetic metal ions on a surface may cause self-sputtering even in the absence of substrate bias. Charge-state-averaged self-sputtering yields were determined for both zirconium and gold ions generated by a cathodic vacuum arc. Films were deposited on differently biased substrates exposed to streaming Zr and Au vacuum arc plasma. The self-sputtering yields for both metals were estimated to be about 0.05 in the absence of bias, and exceeding 0.5 when bias reached-50 V. These surprisingly high values can be reconciled with binary collision theory and molecular dynamics calculations taking high the kinetic and potential energy of vacuum arc ions into account

  20. Measured signatures of low energy, physical sputtering in the line shape of neutral carbon emission

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, N.H. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States)]. E-mail: brooks@fusion.gat.com; Isler, R.C. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169 (United States); Whyte, D.G. [University of Wisconsin, Madison, WI 53706 (United States); Fenstermacher, M.E. [Livermore National Laboratory, Livermore, CA 94550 (United States); Groebner, R.J. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Stangeby, P.C. [University of Toronto Institute for Aerospace Studies, Toronto, M3H 5T6 (Canada); Heidbrink, W.W. [University of California, Irvine, CA 92697 (United States); Jackson, G.L. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Mahdavi, M.A. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); West, W.P. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States)

    2005-03-01

    The most important mechanisms for introducing carbon into the DIII-D divertors [J.L. Luxon, Nucl. Fusion 42 (2002) 614] are physical and chemical sputtering. Previous investigations have indicated that operating conditions where one or the other of these is dominant can be distinguished by using CD and C{sub 2} emissions to infer C I influxes from dissociation of hydrocarbons and comparing to measured C I influxes. The present work extends these results through detailed analysis of the C I spectral line shapes. In general, it is found that the profiles are actually asymmetric and have shifted peaks. These features are interpreted as originating from a combination of an anisotropic velocity distribution from physical sputtering (the Thompson model) and an isotropic distribution from molecular dissociation. The present study utilizes pure helium plasmas to benchmark C I spectral profiles arising from physical sputtering alone.

  1. Spatial distributions of Cu polycrystal sputtered atoms

    International Nuclear Information System (INIS)

    Abgaryan, V.K.; Semenov, A.A.; Shkarban, I.I.

    2004-01-01

    The results of the experimental determination of the Cu atoms spatial distribution, sputtered from the polycrystalline copper target, irradiated by the Xe + ions with the energy of 300 eV, are presented. The spatial distributions of the sputtered particles, calculated through the quasistable-dynamic model of the cascade modeling (CAMO) are presented also for the case of the polycrystalline copper irradiation by the Ar + and Xe + ions with the energy of 300-1000 eV [ru

  2. Sputtering of sodium on the planet Mercury

    Science.gov (United States)

    Mcgrath, M. A.; Johnson, R. E.; Lanzerotti, L. J.

    1986-01-01

    It is shown here that ion sputtering cannot account for the observed neutral sodium vapor column density on Mercury, but that it is an important loss mechanism for Na. Photons are likely to be the dominant stimulus, both directly through photodesorption and indirectly through thermal desorption of absorbed Na. It is concluded that the atmosphere produced is characterized by the planet's surface temperature, with the ion-sputtered Na contributing to a lesser, but more extended, component of the atmosphere.

  3. Heavy particle transport in sputtering systems

    Science.gov (United States)

    Trieschmann, Jan

    2015-09-01

    This contribution aims to discuss the theoretical background of heavy particle transport in plasma sputtering systems such as direct current magnetron sputtering (dcMS), high power impulse magnetron sputtering (HiPIMS), or multi frequency capacitively coupled plasmas (MFCCP). Due to inherently low process pressures below one Pa only kinetic simulation models are suitable. In this work a model appropriate for the description of the transport of film forming particles sputtered of a target material has been devised within the frame of the OpenFOAM software (specifically dsmcFoam). The three dimensional model comprises of ejection of sputtered particles into the reactor chamber, their collisional transport through the volume, as well as deposition of the latter onto the surrounding surfaces (i.e. substrates, walls). An angular dependent Thompson energy distribution fitted to results from Monte-Carlo simulations is assumed initially. Binary collisions are treated via the M1 collision model, a modified variable hard sphere (VHS) model. The dynamics of sputtered and background gas species can be resolved self-consistently following the direct simulation Monte-Carlo (DSMC) approach or, whenever possible, simplified based on the test particle method (TPM) with the assumption of a constant, non-stationary background at a given temperature. At the example of an MFCCP research reactor the transport of sputtered aluminum is specifically discussed. For the peculiar configuration and under typical process conditions with argon as process gas the transport of aluminum sputtered of a circular target is shown to be governed by a one dimensional interaction of the imposed and backscattered particle fluxes. The results are analyzed and discussed on the basis of the obtained velocity distribution functions (VDF). This work is supported by the German Research Foundation (DFG) in the frame of the Collaborative Research Centre TRR 87.

  4. Sputtering on cobalt with noble gas ions

    International Nuclear Information System (INIS)

    Sarholt-Kristensen, L.; Johansen, A.; Johnson, E.

    1983-01-01

    Single crystals of cobalt have been bombarded with 80 keV Ar + ions and with 80 keV and 200 keV Xe + ions in the [0001] direction of the hcp phase and the [111] direction of the fcc phase. The sputtering yield has been measured as function of target temperature (20 0 C-500 0 C), showing a reduction in sputtering yield for 80 keV Ar + ions and 200 keV Xe + ions, when the crystal structure changes from hcp to fcc. In contrast to this, bombardment with 80 keV Xe + ions results in an increase in sputtering yield as the phase transition is passed. Sputtering yields for [111] nickel are in agreement with the sputtering yields for fcc cobalt indicating normal behaviour of the fcc cobalt phase. The higher sputtering yield of [0001] cobalt for certain combinations of ion mass and energy may then be ascribed to disorder induced partly by martensitic phase transformation, partly by radiation damage. (orig.)

  5. Methods and systems for measuring anions

    KAUST Repository

    Masih, Dilshad; Mohammed, Omar F.; Aly, Shawkat M.; Alarousu, Erkki

    2016-01-01

    Embodiments of the present disclosure provide for methods for detecting the presence and/or concentration of anions in a solution, systems for detecting the presence and/or concentration of anions in a solution, anion sensor systems, and the like.

  6. Methods and systems for measuring anions

    KAUST Repository

    Masih, Dilshad

    2016-08-18

    Embodiments of the present disclosure provide for methods for detecting the presence and/or concentration of anions in a solution, systems for detecting the presence and/or concentration of anions in a solution, anion sensor systems, and the like.

  7. Analysing destruction channels of interstellar hydrocarbon anions with a 22pol ion-trap

    Energy Technology Data Exchange (ETDEWEB)

    Endres, Eric; Lakhmanskaya, Olga; Best, Thorsten; Hauser, Daniel; Kumar, Sunil; Wester, Roland [Universitaet Innsbruck, Institut fuer Ionenphysik und Angewandte Physik (Austria)

    2014-07-01

    In the interstellar medium (ISM), ion-molecule reactions are considered to play a key role in the formation of complex molecules. The detection of the first interstellar anions, which happen to be carbon chain anions, has raised new interest in the quantitative composition of the ISM and the underlying reaction network. To understand the observed abundance of these carbon chain anions, a detailed analysis of the possible destruction channels is indispensable. A cryogenic 22-pol radio frequency ion trap is an ideal tool to observe reactions that take place slowly, such as carbon chain anions with molecular hydrogen. Furthermore, measurements over a large temperature scale are feasible. Longitudinal optical access to the trap also provides the possibility to make precise photodetachment measurements. Temperature dependent measurements of the reaction rates for the reaction between hydrocarbon chain anions and H{sub 2} are presented.

  8. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.

    2003-01-01

    and the expulsion of anions; a broad anodic peak centered at ca. - 0.5 V representing the expulsion of cations; and a second broad peak at +0.2 to +0.5 V corresponding to anions being inserted. Although the motion of cations is the most important, as expected, there is a significant anion contribution, thereby...... complicating reproducibility when employing PPy(DBS) polymers as actuators. When the cation is doubly charged, it enters the film less readily, and anions dominate the mobility. Using a large and bulky cation switches the mechanism to apparently total anion motion. The changes in area of the three peaks...

  9. Computer simulation of sputtering of graphite target in magnetron sputtering device with two zones of erosion

    Directory of Open Access Journals (Sweden)

    Bogdanov R.V.

    2015-03-01

    Full Text Available A computer simulation program for discharge in a magnetron sputtering device with two erosion zones was developed. Basic laws of the graphite target sputtering process and transport of sputtered material to the substrate were taken into account in the Monte Carlo code. The results of computer simulation for radial distributions of density and energy flux of carbon atoms on the substrate (at different values of discharge current and pressure of the working gas confirmed the possibility of obtaining qualitative homogeneous films using this magnetron sputtering device. Also the discharge modes were determined for this magnetron sputtering device, in which it was possible to obtain such energy and density of carbon atoms fluxes, which were suitable for deposition of carbon films containing carbon nanotubes and other nanoparticles.

  10. Supramolecular Chemistry of Environmentally Relevant Anions

    International Nuclear Information System (INIS)

    Bowman-James, Kristin; Moyer, B.A.; Sessler, Jonathan L.

    2003-01-01

    The goal of this project is the development of highly selective extractants for anions targeting important and timely problems of critical interest to the EMSP mission. In particular, sulfate poses a special problem in cleaning up the Hanford waste tanks in that it interferes with vitrification, but available technologies for sulfate removal are limited. The basic chemical aspects of anion receptor design of functional pH independent systems as well as design of separations strategies for selective and efficient removal of targeted anions have been probed. Key findings include: (1) some of the first synthetic sulfate-selective anion-binding agents; (2) simple, structure-based methods for modifying the intrinsic anion selectivity of a given class of anion receptors; and (3) the first system capable of extracting sulfate from acidic, nitrate-containing aqueous media. Receptor design, structural influences on anion binding affinities, and findings from liquid-liquid extraction studies will be discussed

  11. Observing Planets and Small Bodies in Sputtered High Energy Atom (SHEA) Fluxes

    Science.gov (United States)

    Milillo, A.; Orsini, S.; Hsieh, K. C.; Baragiola, R.; Fama, M.; Johnson, R.; Mura, A.; Plainaki, Ch.; Sarantos, M.; Cassidy, T. A.; hide

    2012-01-01

    speculates on the possibility of performing remote sensing of exposed bodies using SHEA and suggests the need for quantitative results from laboratory simulations and molecular physic modeling in order to understand SHEA data from planetary missions. In the Appendix, referenced computer simulations using existing sputtering data are reviewed.

  12. Efficiency of superoxide anions in the inactivation of selected dehydrogenases

    International Nuclear Information System (INIS)

    Rodacka, Aleksandra; Serafin, Eligiusz; Puchala, Mieczyslaw

    2010-01-01

    The most ubiquitous of the primary reactive oxygen species, formed in all aerobes, is the superoxide free radical. It is believed that the superoxide anion radical shows low reactivity and in oxidative stress it is regarded mainly as an initiator of more reactive species such as · OH and ONOO - . In this paper, the effectiveness of inactivation of selected enzymes by radiation-generated superoxide radicals in comparison with the effectiveness of the other products of water radiolysis is examined. We investigate three enzymes: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH). We show that the direct contribution of the superoxide anion radical to GAPDH and ADH inactivation is significant. The effectiveness of the superoxide anion in the inactivation of GAPDH and ADG was only 2.4 and 2.8 times smaller, respectively, in comparison with hydroxyl radical. LDH was practically not inactivated by the superoxide anion. Despite the fact that the studied dehydrogenases belong to the same class of enzymes (oxidoreductases), all have a similar molecular weight and are tetramers, their susceptibility to free-radical damage varies. The differences in the radiosensitivity of the enzymes are not determined by the basic structural parameters analyzed. A significant role in inactivation susceptibility is played by the type of amino acid residues and their localization within enzyme molecules.

  13. Efficiency of superoxide anions in the inactivation of selected dehydrogenases

    Energy Technology Data Exchange (ETDEWEB)

    Rodacka, Aleksandra, E-mail: olakow@biol.uni.lodz.p [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, 90-237 Lodz (Poland); Serafin, Eligiusz, E-mail: serafin@biol.uni.lodz.p [Laboratory of Computer and Analytical Techniques, University of Lodz, Banacha 12/16, 90-237 Lodz (Poland); Puchala, Mieczyslaw, E-mail: puchala@biol.uni.lodz.p [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, 90-237 Lodz (Poland)

    2010-09-15

    The most ubiquitous of the primary reactive oxygen species, formed in all aerobes, is the superoxide free radical. It is believed that the superoxide anion radical shows low reactivity and in oxidative stress it is regarded mainly as an initiator of more reactive species such as {sup {center_dot}}OH and ONOO{sup -}. In this paper, the effectiveness of inactivation of selected enzymes by radiation-generated superoxide radicals in comparison with the effectiveness of the other products of water radiolysis is examined. We investigate three enzymes: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), alcohol dehydrogenase (ADH) and lactate dehydrogenase (LDH). We show that the direct contribution of the superoxide anion radical to GAPDH and ADH inactivation is significant. The effectiveness of the superoxide anion in the inactivation of GAPDH and ADG was only 2.4 and 2.8 times smaller, respectively, in comparison with hydroxyl radical. LDH was practically not inactivated by the superoxide anion. Despite the fact that the studied dehydrogenases belong to the same class of enzymes (oxidoreductases), all have a similar molecular weight and are tetramers, their susceptibility to free-radical damage varies. The differences in the radiosensitivity of the enzymes are not determined by the basic structural parameters analyzed. A significant role in inactivation susceptibility is played by the type of amino acid residues and their localization within enzyme molecules.

  14. Preparation of Acrylamide-based Anionic Polyelectrolytes for Soil Establishment

    Directory of Open Access Journals (Sweden)

    Ahmad Rabiee

    2012-12-01

    Full Text Available Synthetic water soluble acrylamide-based polymers have wide range of ap-plications  in  the  feld  of  soil  establishment  and  non-desertifcation.  In  this research, the acrylamide-based anionic polyelectrolytes were prepared by  solution polymerization. The polymerization was carried out using AIBN as a radical initiator and at different degrees of anionic charges ranging between 10% and 30% using sodium hydroxide as hydrolyzing agents. The chemical structure of the  synthetic polymers was studied and confrmed by FTIR technique. The charge density on polymer backbone was determined by titration method. The rheological behavior of polymer solutions was evaluated by Brookfeld viscometer. The results show that the viscosity decreases with increasing the shear rate of solutions. Molecular weights of samples were measured by laser light scattering analyzer. The morphology of the polymer was studied by SEM and the EDX was used for elemental analysis determination. The anionic polymers with 10-30% negative charges were mixed with clay in order to evaluate the soil establishment. The results show that an anionic polyelectro-lyte can make soil particles more cohesive and improve soil physical properties.

  15. Anion

    Directory of Open Access Journals (Sweden)

    A. Vadivel Murugan

    2003-01-01

    . Its characterization is investigated by Fourier Transform Infrared Spectroscopy (FT-IR and Scanning Electron Microscopy (SEM. The hybrid material presents predominantly high electronic conductivities of around 2.0 and 7.0 S cm-1 at 300 and 400K respectively.

  16. Vibrational Fano resonances in the photodetachment of dipole-bound anions

    International Nuclear Information System (INIS)

    Edwards, Stephen T; Tully, John C; Johnson, Mark A

    2012-01-01

    A simple model for the photodetachment of dipole-bound anions is proposed where non-adiabatic coupling of vibrational states leads to a Fano resonance in the spectrum. It is found that the shape of the photodetachment spectrum depends significantly on the parameter representing molecular polarizability. The model is also applied to a Fano profile observed in the photodetachment of small water cluster anions.

  17. Sputtering properties of tungsten 'fuzzy' surfaces

    International Nuclear Information System (INIS)

    Nishijima, D.; Baldwin, M.J.; Doerner, R.P.; Yu, J.H.

    2011-01-01

    Sputtering yields of He-induced W 'fuzzy' surfaces bombarded by Ar have been measured in the linear divertor plasma simulator PISCES-B. It is found that the sputtering yield of a fuzzy surface, Y fuzzy , decreases with increasing fuzzy layer thickness, L, and saturates at ∼10% of that of a smooth surface, Y smooth , at L > 1 μm. The reduction in the sputtering yield is suspected to be due mainly to the porous structure of fuzz, since the ratio, Y fuzzy /Y smooth follows (1 - p fuzz ), where p fuzz is the fuzz porosity. Further, Y fuzzy /Y smooth is observed to increase with incident ion energy, E i . This may be explained by an energy dependent change in the angular distribution of sputtered W atoms, since at lower E i , the angular distribution is observed to become more butterfly-shaped. That is, a larger fraction of sputtered W atoms can line-of-sight deposit/stick onto neighboring fuzz nanostructures for lower E i butterfly distributions, resulting in lower ratio of Y fuzzy /Y smooth .

  18. Sputtering of octatetraene by 15 keV C{sub 60} projectiles: Comparison of reactive interatomic potentials

    Energy Technology Data Exchange (ETDEWEB)

    Kanski, Michal; Maciazek, Dawid; Golunski, Mikolaj; Postawa, Zbigniew, E-mail: zbigniew.postawa@uj.edu.pl

    2017-02-15

    Highlights: • Probing the effect of interatomic potentials on sputtering of an octatetraene sample. • Problems with charge calculations are observed during cluster impact for ReaxFF. • COMB3 leads to a very low sputtering yield due to abrupt energy dissipation. • AIREBO is computationally the most efficient, while ReaxFF is more accurate. - Abstract: Molecular dynamics computer simulations have been used to probe the effect of the AIREBO, ReaxFF and COMB3 interatomic potentials on sputtering of an organic sample composed of octatetraene molecules. The system is bombarded by a 15 keV C{sub 60} projectile at normal incidence. The effect of the applied force fields on the total time of simulation, the calculated sputtering yield and the angular distribution of sputtered particles is investigated and discussed. It has been found that caution should be taken when simulating particles ejection from nonhomogeneous systems that undergo significant fragmentation described by the ReaxFF. In this case, the charge state of many particles is improper due to an inadequacy of a procedure used for calculating partial charges on atoms in molecules for conditions present during sputtering. A two-step simulation procedure is proposed to minimize the effect of this deficiency. There is also a possible problem with the COMB3 potential, at least at conditions present during cluster impact, as its results are very different from AIREBO or ReaxFF.

  19. Physical sputtering of metallic systems by charged-particle impact

    International Nuclear Information System (INIS)

    Lam, N.Q.

    1989-12-01

    The present paper provides a brief overview of our current understanding of physical sputtering by charged-particle impact, with the emphasis on sputtering of metals and alloys under bombardment with particles that produce knock-on collisions. Fundamental aspects of ion-solid interactions, and recent developments in the study of sputtering of elemental targets and preferential sputtering in multicomponent materials are reviewed. We concentrate only on a few specific topics of sputter emission, including the various properties of the sputtered flux and depth of origin, and on connections between sputtering and other radiation-induced and -enhanced phenomena that modify the near-surface composition of the target. The synergistic effects of these diverse processes in changing the composition of the integrated sputtered-atom flux is described in simple physical terms, using selected examples of recent important progress. 325 refs., 27 figs

  20. Solar wind sputtering of small bodies: Exospheres of Phobos and Deimos

    Science.gov (United States)

    Schaible, M. J.; Johnson, R. E.; Lee, P.; Benna, M.; Elphic, R. C.

    2014-12-01

    Solar wind, magnetospheric ions and micrometeorites impact the surface of airless bodies in the solar system and deposit energy in the surface material. Excitation and momentum transfer processes lead to sputtering or desorption of molecules and atoms, thereby creating a dynamic exosphere about an otherwise airless body. Ion mass spectrometry of ejected materials provides a highly sensitive method for detecting sputter products and determining the surface composition [Johnson and Baragiola, 1991; Elphic et al., 1991]. Though most of the material is sputtered as neutral gas, UV photons can ionize ejected neutrals and a small fraction of the ejecta leaves the surface in an ionized state. However, ions are deflected by the variably-oriented solar wind magnetic field and thus relating their detection to a surface location can be problematic. Here we estimate the average ion density close to the surface of Phobos or Deimos to predict whether modern mass spectrometry instruments [Mahaffey et al. 2014] would be able to obtain sufficient compositional information to place constraints on their origin. The open source Monte Carlo program SRIM.SR was used to simulate the effect of ions incident onto a surface representing several different meteorite compositions and gave estimates of the damage and sputtering effects. As much of the empirical data supporting SRIM results comes from sputtering of metallic and organic molecular targets which can differ greatly from materials that make up planetary surfaces, measurements of cohesive energies and enthalpies of formation were used to estimate the surface binding energies for minerals, though these can vary significantly depending on the chemical composition. Since these properties affect the sputtering yield, comparisons of simulations with laboratory measurements were made to test the validity of our estimates. Using the validated results and a constant fraction to estimate ion yields, the density of ejected ions and neutrals vs

  1. Quantitative sputter profiling at surfaces and interfaces

    International Nuclear Information System (INIS)

    Kirschner, J.; Etzkorn, H.W.

    1981-01-01

    The key problem in quantitative sputter profiling, that of a sliding depth scale has been solved by combined Auger/X-ray microanalysis. By means of this technique and for the model system Ge/Si (amorphous) the following questions are treated quantitatively: shape of the sputter profiles when sputtering through an interface and origin of their asymmetry; precise location of the interface plane on the depth profile; broadening effects due to limited depth of information and their correction; origin and amount of bombardment induced broadening for different primary ions and energies; depth dependence of the broadening, and basic limits to depth resolution. Comparisons are made to recent theoretical calculations based on recoil mixing in the collision cascade and very good agreement is found

  2. Sputtering as a means of depth profiling

    International Nuclear Information System (INIS)

    Whitton, J.L.

    1978-01-01

    Probably the most common technique for determination of depth profiles by sputtering is that of secondary ion mass spectrometry. Many problems occur in the important step of converting the time (of sputtering) scale to a depth scale and these problems arise before the secondary ions are ejected. An attempt is made to present a comprehensive list of the effects that should be taken into consideration in the use of sputtering as a means of depth profiling. The various parameters liable to affect the depth profile measurements are listed in four sections: beam conditions; target conditions; experimental environment; and beam-target interactions. The effects are discussed and where interplay occurs, cross-reference is made and examples are provided where possible. (B.R.H.)

  3. Environmental behavior of inorganic anions

    International Nuclear Information System (INIS)

    Garland, T.R.; Cataldo, D.A.; Fellows, R.J.; Wildung, R.E.

    1987-01-01

    Recent efforts have addressed two aspects of anion behavior in the soil/plant system. The first involves evaluation of the gaseous component of the terrestrial iodine cycle in soils and plants. Field analyses of 129 I in soils and vegetation adjacent to a fuels reprocessing facility, which was idle for 10 years prior to the study, indicated that there may be a significant gaseous component to the terrestrial iodine cycle. Soil substrates, including a silt-sand, organic forest soil, quartz sand, and a sterilized soil, were amended with radioiodide, and the rates and quality of the volatile components evaluated

  4. Molecular dynamics simulations of hydrophobous ions at the liquid-liquid interfaces: case of dicarbollide anions as synergy agents and of ionic liquids as extracting medium; Simulations par dynamique moleculaire d'ions hydrophobes aux interfaces liquide - liquide: le cas des anions dicarbollides comme agents de synergie et celui des liquides ioniques comme milieu extractant

    Energy Technology Data Exchange (ETDEWEB)

    Chevrot, G

    2008-01-15

    Based on molecular dynamics simulations, we first describe the distribution of dicarbollide salts (CCD{sup -}, Mn{sup +}) in concentrated monophasic solutions (water, chloroform, octanol, nitrobenzene) and in the corresponding biphasic 'oil' - water solutions. We point to the importance of surface activity of the CCD{sup -}s and of their self-aggregation in water, with marked counterions effects, and we explain the synergistic effect of CCD{sup -}s in the Eu{sup 3+} extraction by BTP ligands. In the second part of the thesis we report exploratory simulations on the extraction of Sr{sup 2+} by 18-crown-6 to an hydrophobic ionic liquid ([BMI][PF6]), focusing on the liquid - liquid interface. Analogies and differences with a classical aqueous interface are outlined. (author)

  5. Sputtering yield calculation for binary target

    International Nuclear Information System (INIS)

    Jimenez-Rodriguez, J.J.; Rodriguez-Vidal, M.; Valles-Abarca, J.A.

    1979-01-01

    The generalization for binary targets, of the ideas proposed by Sigmund for monoatomic targets, leads to a set of coupled intergrodifferential equations for the sputtering functions. After moment decomposition, the final formulae are obtained by the standard method based on the Laplace Transform, where the inverse transform is made with the aid of asymptotic expansions in the limit of very high projectile energy as compared to the surface binding energy. The possible loss of stoichiometry for binary targets is analyzed. Comparison of computed values of sputtering yield for normal incidence, with experimental results shows good agreement. (author)

  6. Photonometers for coating and sputtering machines

    Directory of Open Access Journals (Sweden)

    Václavík J.

    2013-05-01

    Full Text Available The concept of photonometers (alternative name of optical monitor of a vacuum deposition process for coating and sputtering machines is based on photonometers produced by companies like SATIS or HV Dresden. Photometers were developed in the TOPTEC centre and its predecessor VOD (Optical Development Workshop of Institut of Plasma Physics AS CR for more than 10 years. The article describes current status of the technology and ideas which will be incorporated in next development steps. Hardware and software used on coating machines B63D, VNA600 and sputtering machine UPM810 is presented.

  7. Photonometers for coating and sputtering machines

    Science.gov (United States)

    Oupický, P.; Jareš, D.; Václavík, J.; Vápenka, D.

    2013-04-01

    The concept of photonometers (alternative name of optical monitor of a vacuum deposition process) for coating and sputtering machines is based on photonometers produced by companies like SATIS or HV Dresden. Photometers were developed in the TOPTEC centre and its predecessor VOD (Optical Development Workshop of Institut of Plasma Physics AS CR) for more than 10 years. The article describes current status of the technology and ideas which will be incorporated in next development steps. Hardware and software used on coating machines B63D, VNA600 and sputtering machine UPM810 is presented.

  8. Dependence of sputtering coefficient on ion dose

    International Nuclear Information System (INIS)

    Colligon, J.S.; Patel, M.H.

    1977-01-01

    The sputtering coefficient of polycrystalline gold bombarded by 10-40 keV Ar + ions had been measured as a function of total ion dose and shown to exhibit oscillations in magnitude between 30 and 100%. Possible experimental errors which would give rise to such an oscillation have been considered, but it is apparent that these factors are unable to explain the measurements. It is proposed that a change in the Sublimation Energy associated with either bulk damage or formation of surface topographical features arising during ion bombardment may be responsible for the observed variations in sputtering coefficient. (author)

  9. Carbonaceous Particles Production in a Sputtering Discharge

    International Nuclear Information System (INIS)

    Dominique, Claire; Sant, Marco; Arnas, Cecile

    2005-01-01

    Spherical dust particles have been produced in argon glow discharge by sputtering of a graphite cathode. Their size varies from 40 to 200 nm depending on the distance between the two electrodes and the largest ones have a cauliflower shape. Simulations giving the evolution of the energy distribution of sputtered carbon atoms suggest a mechanism of growth by carbon vapour condensation. The chemical composition and structure of particles have been investigated by infrared spectroscopy and appear to be a complex arrangement of the carbon atoms and hetero-atoms

  10. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands for time and skilled technical personnel, HVTs are currently used in only a few research laboratories worldwide. Instead, most researchers in this filed are attracted to more facile Schlenk techniques. The basic principle of this technique followed in all laboratories is substantially the same, i.e. the use of alternate vacuum and inert gas atmosphere in glass apparatus for the purification/charging of monomer, solvents, additives, and for the manipulation of air-sensitive compounds such as alkyl metal initiators, organometallic or organic catalysts. However, it is executed quite differently in each research group in terms of the structure of Schlenk apparatus (manifolds, connections, purification/storage flasks, reactors, etc.), the use of small supplementary devices (soft tubing, cannulas, stopcocks, etc.) and experimental procedures. The operational methods are partly purpose-oriented while also featured by a high flexibility, which makes it impossible to describe in detail each specific one. In this chapter we will briefly exemplify the application of Schlenk techniques for anionic polymerization by describing the performance of a few experiments from our own work.

  11. Lowest auto-detachment state of the water anion

    International Nuclear Information System (INIS)

    Houfek, K.; Cizek, M.

    2016-01-01

    Because of the abundance of water in living tissue the reactive low-energy electron collisions with the water molecule represent an important step in the radiation damage of cells. In this paper, the potential energy surface of the ground state of the water anion H_2O"- is carefully mapped using multireference configuration interaction (MRCI) calculations for a large range of molecular geometries. Particular attention is paid to a consistent description of both the O"-+H_2 and OH"-+H asymptotes and to a relative position of the anion energy to the ground state energy of the neutral molecule. The auto-detachment region, where the anion state crosses to the electronic continuum is identified. The local minimum in the direction of the O"- + H_2 channel previously reported by Werner et al. [J. Chem. Phys. 87, 2913 (1987)] is found to be slightly off the linear geometry and is separated by a saddle from the auto-detachment region. The auto-detachment region is directly accessible from the OH"-+H asymptote. For the molecular geometries in the auto-detachment region and in its vicinity we also performed fixed-nuclei electron-molecule scattering calculations using the R-matrix method. Tuning of consistency of a description of the correlation energy in both the multireference CI and R-matrix calculations is discussed. Two models of the correlation energy within the R-matrix method that are consistent with the quantum chemistry calculations are found. Both models yield scattering quantities in a close agreement. The results of this work will allow a consistent formulation of the nonlocal resonance model of the water anion in a future publication

  12. Round Robin computer simulation of ejection probability in sputtering

    International Nuclear Information System (INIS)

    Sigmund, P.; Hautala, M.; Yamamura, Y.; Hosaka, S.; Ishitani, T.; Shulga, V.I.; Harrison, D.E. Jr.; Chakarov, I.R.; Karpuzov, D.S.; Kawatoh, E.; Shimizu, R.; Valkealahti, S.; Nieminen, R.M.; Betz, G.; Husinsky, W.; Shapiro, M.H.; Vicanek, M.; Urbassek, H.M.

    1989-01-01

    We have studied the ejection of a copper atom through a planar copper surface as a function of recoil velocity and depth of origin. Results were obtained from six molecular dynamics codes, four binary collision lattice simulation codes, and eight Monte Carlo codes. Most results were found with a Born-Mayer interaction potential between the atoms with Gibson 2 parameters and a planar surface barrier, but variations on this standard were allowed for, as well as differences in the adopted cutoff radius for the interaction potential, electronic stopping, and target temperature. Large differences were found between the predictions of the various codes, but the cause of these differences could be determined in most cases. A fairly clear picture emerges from all three types of codes for the depth range and the angular range for ejection at energies relevant to sputter ejection, although a quantitative discussion would have to include an analysis of replacement collision events which has been left out here. (orig.)

  13. KRYPTON INCORPORATION IN SPUTTERED SILICON FILMS

    NARCIS (Netherlands)

    GREUTER, MJW; NIESEN, L; HAKVOORT, RA; DEROODE, J; VANVEEN, A; BERNTSEN, AJM; SLOOF, WG

    1993-01-01

    The incorporation of Kr in sputtered a-Si films has been investigated in a systematic way by varying the Kr to Si flux, yielding Kr concentrations up to 5 at %. Compositions were determined with X-ray microanalysis. A model has been applied to describe the composition of the growing film. The layers

  14. Lithium insertion in sputtered vanadium oxide film

    DEFF Research Database (Denmark)

    West, K.; Zachau-Christiansen, B.; Skaarup, S.V.

    1992-01-01

    were oxygen deficient compared to V2O5. Films prepared in pure argon were reduced to V(4) or lower. The vanadium oxide films were tested in solid-state lithium cells. Films sputtered in oxygen showed electrochemical properties similar to crystalline V2O5. The main differences are a decreased capacity...

  15. Reactive magnetron sputtering of Si-C-N films with controlled mechanical and optical properties

    Czech Academy of Sciences Publication Activity Database

    Vlček, J.; Kormunda, M.; Čížek, J.; Soukup, Z.; Peřina, Vratislav; Zemek, Josef

    2003-01-01

    Roč. 12, č. 8 (2003), s. 1287-1294 ISSN 0925-9635 R&D Projects: GA MŠk ME 203; GA MŠk OC 527.90 Institutional research plan: CEZ:MSM 235200002 Keywords : silicon-carbon-nitride films * magnetron co-sputtering Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.867, year: 2003

  16. Pulsed dc self-sustained magnetron sputtering

    International Nuclear Information System (INIS)

    Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

    2008-01-01

    The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of ∼0.5 Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50 mm diameter and 6 mm thick copper target was used during the experiments. The maximum target power was about 11 kW, which corresponded to the target power density of ∼560 W/cm 2 . The magnetron operation was investigated as a function of pulse frequency (20-100 kHz) and pulse duty factor (50%-90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400-410 nm range) and deposition

  17. Atomistic self-sputtering mechanisms of rf breakdown in high-gradient linacs

    International Nuclear Information System (INIS)

    Insepov, Z.; Norem, J.; Veitzer, S.

    2010-01-01

    Molecular dynamics (MD) models of sputtering solid and liquid surfaces - including the surfaces charged by interaction with plasma, Coulomb explosion, and Taylor cone formation - were developed. MD simulations of self-sputtering of a crystalline (1 0 0) copper surface by Cu + ions in a wide range of ion energies (50 eV-50 keV) were performed. In order to accommodate energetic ion impacts on a target, a computational model was developed that utilizes MD to simulate rapid atomic collisions in the central impact zone, and a finite-difference method to absorb the energy and shock wave for the collisional processes occurring at a longer time scales. The sputtering yield increases if the surface temperature rises and the surface melts as a result of heat from plasma. Electrostatic charging of the surface under bombardment with plasma ions is another mechanism that can dramatically increase the sputtering yield because it reduces the surface binding energy and the surface tension. An MD model of Taylor cone formation at a sharp tip placed in a high electric field was developed, and the model was used to simulate Taylor cone formation for the first time. Good agreement was obtained between the calculated Taylor cone angle (104.3 deg.) and the experimental one (98.6 deg.). A Coulomb explosion (CE) was proposed as the main surface failure mechanism triggering breakdown, and the dynamics of CE was studied by MD.

  18. Sputtering of thin benzene and polystyrene overlayers by keV Ga and C60 bombardment

    International Nuclear Information System (INIS)

    Czerwinski, B.; Delcorte, A.; Garrison, B.J.; Samson, R.; Winograd, N.; Postawa, Z.

    2006-01-01

    The mechanisms of ion-stimulated desorption of thin organic overlayers deposited on metal substrates by mono- and polyatomic projectiles are examined using molecular dynamics (MD) computer simulations. A monolayer of polystyrene tetramers (PS4) physisorbed on Ag{1 1 1} is irradiated by 15 keV Ga and C 60 projectiles at normal incidence. The results are compared with the data obtained for a benzene overlayer to investigate the differences in sputtering mechanisms of weakly and strongly bound organic molecules. The results indicate that the sputtering yield decreases with the increase of the binding energy and the average kinetic energy of parent molecules is shifted toward higher kinetic energy. Although the total sputtering yield of organic material is larger for 15 keV C 60 , the impact of this projectile leads to a significant fragmentation of ejected species. As a result, the yield of the intact molecules is comparable for C 60 and Ga projectiles. Our data indicate that chemical analysis of the very thin organic films performed by detection of sputtered neutrals will not benefit from the use of C 60 projectiles

  19. Production of rare-earth atomic negative ion beams in a cesium-sputter-type negative ion source

    International Nuclear Information System (INIS)

    Davis, V.T.; Covington, A.M.; Duvvuri, S.S.; Kraus, R.G.; Emmons, E.D.; Kvale, T.J.; Thompson, J.S.

    2007-01-01

    The desire to study negative ion structure and negative ion-photon interactions has spurred the development of ion sources for use in research and industry. The many different types of negative ion sources available today differ in their characteristics and abilities to produce anions of various species. Thus the importance of choosing the correct type of negative ion source for a particular research or industrial application is clear. In this study, the results of an investigation on the production of beams composed of negatively-charged rare-earth ions from a cylindrical-cathode-geometry, cesium-sputter-type negative ion source are presented. Beams of atomic anions have been observed for most of the first-row rare-earth elements, with typical currents ranging from hundreds of picoamps to several nanoamps

  20. Test procedure for anion exchange chromatography

    International Nuclear Information System (INIS)

    Cooper, T.D.

    1994-01-01

    Plutonium from stored nitrate solutions will be sorbed onto anion exchange resins and converted to storable plutonium dioxide. Useful information will be simultaneously gained on the thermal stability and ion exchange capacity of four commercially available anion exchange resins over several years and under severe degradative conditions. This information will prove useful in predicting the safe and efficient lifetimes of these resins

  1. Tripodal Receptors for Cation and Anion Sensors

    Directory of Open Access Journals (Sweden)

    David N. Reinhoudt

    2006-08-01

    Full Text Available This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  2. Neutral anion receptors: design and application

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Reinhoudt, David

    1998-01-01

    After the development of synthetic cation receptors in the late 1960s, only in the past decade has work started on the development of synthetic neutral anion receptors. Combination and preorganization of different anion binding groups, like amides, urea moieties, or Lewis acidic metal centers lead

  3. Anion Gap Blood Test: MedlinePlus Lab Test Information

    Science.gov (United States)

    ... https://medlineplus.gov/labtests/aniongapbloodtest.html Anion Gap Blood Test To use the sharing features on this page, please enable JavaScript. What is an Anion Gap Blood Test? An anion gap blood test is a way ...

  4. Synthesis of ReN3 Thin Films by Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    G. Soto

    2014-01-01

    Full Text Available In this work ReNx films were prepared by reactive magnetron sputtering at room temperature and deposited on a silicon wafer. It was found that the diffractograms of the nitrogen-rich rhenium film are consistent with those produced by high-pressure high-temperature methods, under the assumption that the film is oriented on the substrate. Using density functional calculations it was found that the composition of this compound could be ReN3, instead of ReN2, as stated on previous works. The ReN3 compound fits in the Ama2 (40 orthorhombic space group, and due to the existence of N3 anions between Re layers it should be categorized as an azide. The material is exceptionally brittle and inherently unstable under indentation testing.

  5. Anion-π Catalysts with Axial Chirality.

    Science.gov (United States)

    Wang, Chao; Matile, Stefan

    2017-09-04

    The idea of anion-π catalysis is to stabilize anionic transition states by anion-π interactions on aromatic surfaces. For asymmetric anion-π catalysis, π-acidic surfaces have been surrounded with stereogenic centers. This manuscript introduces the first anion-π catalysts that operate with axial chirality. Bifunctional catalysts with tertiary amine bases next to π-acidic naphthalenediimide planes are equipped with a bulky aromatic substituent in the imide position to produce separable atropisomers. The addition of malonic acid half thioesters to enolate acceptors is used for evaluation. In the presence of a chiral axis, the selective acceleration of the disfavored but relevant enolate addition was much better than with point chirality, and enantioselectivity could be observed for the first time for this reaction with small-molecule anion-π catalysts. Enantioselectivity increased with the π acidity of the π surface, whereas the addition of stereogenic centers around the aromatic plane did not cause further improvements. These results identify axial chirality of the active aromatic plane generated by atropisomerism as an attractive strategy for asymmetric anion-π catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Transport theory of sputtering I: Depth of origin of sputtered atoms

    International Nuclear Information System (INIS)

    Zhang, Z.L.

    1999-01-01

    Sputter theory employing a sum of two power cross sections has been implemented. Compared with the well known Lindhard power cross section (V∝r -1/m ), a sum of two such cross sections can give a much better approximation to the Born-Mayer scattering in the low energy region (m ∼ 0.1). By using both one and two power cross sections, we have solved the linear transport equations describing the sputtering problem asymptotically. As usual, electronic stopping is ignored in the analysis. It has further been proved that Falcone's theory of the atom ejection process contradicts transport theory. The Andersen-Sigmund relation for partial sputtering yield ratios between two elements in an arbitrary multicomponent target has been derived by both methods. The energy deposited in the target surface layers has been computed for a few typical ion-target combinations. The numerical curves show that both theories generate almost the same results (error <10%) for m=3D0.2. It is also shown that, if the sputtering yield equals the corresponding one in Sigmund's theory, the depth of origin of sputtered atoms must be shorter than in Sigmund's theory for 0.25 m ≥ 3D 0. The former even may be only about one half of the latter as long as m=3D0. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  7. Pumping behavior of sputter ion pumps

    International Nuclear Information System (INIS)

    Chou, T.S.; McCafferty, D.

    The ultrahigh vacuum requirements of ISABELLE is obtained by distributed pumping stations. Each pumping station consists of 1000 l/s titanium sublimation pump for active gases (N 2 , H 2 , O 2 , CO, etc.), and a 20 l/s sputter ion pump for inert gases (methane, noble gases like He, etc.). The combination of the alarming production rate of methane from titanium sublimation pumps (TSP) and the decreasing pumping speed of sputter ion pumps (SIP) in the ultrahigh vacuum region (UHV) leads us to investigate this problem. In this paper, we first describe the essential physics and chemistry of the SIP in a very clean condition, followed by a discussion of our measuring techniques. Finally measured methane, argon and helium pumping speeds are presented for three different ion pumps in the range of 10 -6 to 10 -11 Torr. The virtues of the best pump are also discussed

  8. XPS studies of water and oxygen on iron-sputtered natural ilmenite

    Science.gov (United States)

    Schulze, P. D.; Neil, T. E.; Shaffer, S. L.; Smith, R. W.; Mckay, D. S.

    1985-01-01

    The adsorption of D2O and O2 on polycrystalline FeTiO3 (natural ilmenite) has been studied by X-ray photoelectron spectroscopy. Oxygen was found to absorb reactively with Fe(0) on Ar(+)-sputtered surfaces at and above 150 K while D2O was found to adsorb molecularly or in ice layers below 170 K on both Ar(+) and O2(+) ion-bombarded ilmenite. The D2O desorbs at 170 K with either the formation of an OD complex or a strongly bound molecular layer of water.

  9. Niobium sputter deposition on quarter wave resonators

    CERN Document Server

    Viswanadham, C; Jayaprakash, D; Mishra, R L

    2003-01-01

    Niobium sputter deposition on quarter wave copper R.F resonators, have been taken up in our laboratory, An ultra high vacuum system was made for this purpose. Niobium exhibits superconducting properties at liquid Helium temperature. A uniform coating of about 1.5 mu m of niobium on the internal surfaces of the copper resonant cavities is desired. Power dissipation in the resonators can be greatly reduced by making the internal surfaces of the R.F cavity super conducting. (author)

  10. Sputter coating of microspherical substrates by levitation

    Science.gov (United States)

    Lowe, A.T.; Hosford, C.D.

    Microspheres are substantially uniformly coated with metals or nonmetals by simltaneously levitating them and sputter coating them at total chamber pressures less than 1 torr. A collimated hole structure comprising a parallel array of upwardly projecting individual gas outlets is machined out to form a dimple. Glass microballoons,, which are particularly useful in laser fusion applications, can be substantially uniformly coated using the coating method and apparatus.

  11. Origins of Beta Tantalum in Sputtered Coatings

    National Research Council Canada - National Science Library

    Mulligan, C

    2001-01-01

    .... Some of the most recent work has attempted to relate the energetics (i.e., atom/ion energy) of the plasma to the alpha right arrow beta transition. It has been shown that the energetics of the plasma can relate to the most crucial sputtering parameters. The most significant feature of the use of plasma energy to explain the alpha right arrow beta transition is that it relates the formation of beta-tantalum to a quantifiable measure.

  12. Epitaxial growth of rhenium with sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Seongshik [National Institute of Standards and Technology, Boulder, CO 80305 (United States) and Department of Physics, University of Illinois, Urbana, IL 61801 (United States)]. E-mail: soh@boulder.nist.gov; Hite, Dustin A. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Cicak, K. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Osborn, Kevin D. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Simmonds, Raymond W. [National Institute of Standards and Technology, Boulder, CO 80305 (United States); McDermott, Robert [University of California, Santa Barbara, CA 93106 (United States); Cooper, Ken B. [University of California, Santa Barbara, CA 93106 (United States); Steffen, Matthias [University of California, Santa Barbara, CA 93106 (United States); Martinis, John M. [University of California, Santa Barbara, CA 93106 (United States); Pappas, David P. [National Institute of Standards and Technology, Boulder, CO 80305 (United States)

    2006-02-21

    We have grown epitaxial Rhenium (Re) (0001) films on {alpha}-Al{sub 2}O{sub 3} (0001) substrates using sputter deposition in an ultra high vacuum system. We find that better epitaxy is achieved with DC rather than with RF sputtering. With DC sputtering, epitaxy is obtained with the substrate temperatures above 700 deg. C and deposition rates below 0.1 nm/s. The epitaxial Re films are typically composed of terraced hexagonal islands with screw dislocations, and island size gets larger with high temperature post-deposition annealing. The growth starts in a three dimensional mode but transforms into two dimensional mode as the film gets thicker. With a thin ({approx}2 nm) seed layer deposited at room temperature and annealed at a high temperature, the initial three dimensional growth can be suppressed. This results in larger islands when a thick film is grown at 850 deg. C on the seed layer. We also find that when a room temperature deposited Re film is annealed to higher temperatures, epitaxial features start to show up above {approx}600 deg. C, but the film tends to be disordered.

  13. Lixiviação de cátions favorecida pela presença de ânions inorgânicos e ácidos orgânicos de baixa massa molecular em solos adubados com camas de aviário Cation leaching favored by inorganic anions and low molecular mass organic acids in soils fertilized with different poultry litters

    Directory of Open Access Journals (Sweden)

    Fabrício de Oliveira Gebrim

    2008-12-01

    textura média, Cl-e NO3-no solo de textura argilosa e, de maneira menos expressiva, pelo efeito acompanhante/complexante dos ácidos orgânicos de baixa massa molecular. No solo argiloso, a percolação de Ca esteve positivamente correlacionada com a concentração dos ácidos málico e oxálico. A concomitante elevada concentração de ácido acético nos percolados de solos tratados com todas as camas sugere que este pode estar favorecendo a lixiviação de bases no solo, provavelmente como ânion acompanhante.The exponential growth in poultry farming in Brazil has led to a parallel increase in the production of manure and poultry litter. The litter generated in this activity used to be largely employed as cattle feed. However, the enactment of a law that bans the use of poultry litter as animal feed intensified its use as organic fertilizer in agriculture. Despite its importance, there are gaps in our knowledge on an adequate use to obtain high plant yields without threatening the environment. One of these gaps is base-leaching in the soil profile as a result of the presence of accompanying anions such as chloride, nitrate and sulphate, and the complexing effect of low molecular mass organic acids. Samples of two Oxisols (a clayey and a sandy loam Red-Yellow Latosol were placed in PVC columns. Each column consisted of five PVC rings (5 cm diameter, 10 cm height fixed to each other with scotch tape. Five types of poultry litter (coffee husks, ground corn cob, rice husk, napier grass and wood shavings were homogenously applied to the soil in the top ring in a dose equivalent to 160 t ha-1 (dry weight basis. The treatments consisted of a 5 x 2 + 1 factorial combination, corresponding to five poultry litter types, two soils with distinct textures, and a control treatment with no poultry litter application, with five repetitions, arranged in a complete randomized block design. Deionized water was applied on top of the columns twice a week, in a total volume corresponding

  14. Influence of surface topography on the sputtering yields of silver

    International Nuclear Information System (INIS)

    Pan Jisheng; Wang Zhenxia; Tao Zhenlan; Zhang Jiping

    1992-01-01

    The sputtering yields of silver have been measured as a function of the fluence of incident Ar + ions (27 keV) using the collector technique and RBS analysis. The irradiated surface was examined by scanning electron microscopy (SEM). It is shown that the sputtering yields of surfaces with topography are enhanced relative to smooth surfaces of silver, but the extent of the enhancement depends on the irradiation dose. The experimental results can be explained assuming that the surface topography and sputtering yield are a function of incident angle. It is obvious that the surface topography is an important factor to influence the sputtering yield. The term ''apparent sputtering yield'' has specifically been used when referring to the experimental sputtering yield of a surface with topography, to emphasize the difference with a smooth surface. (orig.)

  15. Tests of a new axial sputtering technique in an ECRIS

    International Nuclear Information System (INIS)

    Scott, R.; Pardo, R.; Vondrasek, R.

    2012-01-01

    Axial and radial sputtering techniques have been used over the years to create beams from an ECRIS at multiple accelerator facilities. Operational experience has shown greater beam production when using the radial sputtering method versus axial sputtering. At Argonne National Laboratory, previous work with radial sputtering has demonstrated that the position of the sputter sample relative to the plasma chamber wall influences sample drain current, beam production and charge state distribution. The possibility of the chamber wall acting as a ground plane which influences the sputtering of material has been considered, and an attempt has been made to mimic this possible ground plane effect with a coaxial sample introduced from the injection end. Results of these tests will be shown as well as comparisons of outputs using the two methods. The paper is followed by the associated poster. (authors)

  16. Dwell time dependent morphological transition and sputtering yield of ion sputtered Sn

    International Nuclear Information System (INIS)

    Qian, H X; Zeng, X R; Zhou, W

    2010-01-01

    Self-organized nano-scale patterns may appear on a wide variety of materials irradiated with an ion beam. Good manipulation of these structures is important for application in nanostructure fabrication. In this paper, dwell time has been demonstrated to be able to control the ripple formation and sputtering yield on Sn surface. Ripples with a wavelength of 1.7 μm were observed for a dwell time in the range 3-20 μs, whereas much finer ripples with a wavelength of 540 nm and a different orientation were observed for a shorter dwell time in the range 0.1-2 μs. The sputtering yield increases with dwell time significantly. The results provide a new basis for further steps in the theoretical description of morphology evolution during ion beam sputtering.

  17. Sensitive coating for water vapors detection based on thermally sputtered calcein thin films.

    Science.gov (United States)

    Kruglenko, I; Shirshov, Yu; Burlachenko, J; Savchenko, A; Kravchenko, S; Manera, M G; Rella, R

    2010-09-15

    In this paper the adsorption properties of thermally sputtered calcein thin films towards water and other polar molecules vapors are studied by different characterization techniques: quartz crystal microbalance, surface plasmon resonance and visible spectroscopy. Sensitivity of calcein thin films to water vapors resulted much higher as compared with those of a number of dyes whose structure was close to that of calcein. All types of sensors with calcein coatings have demonstrated linear concentration dependences in the wide range of water vapor pressure from low concentrations up to 27,000 ppm (close to saturation). At higher concentrations of water vapor all sensors demonstrate the abrupt increase of the response (up to two orders). A theoretical model is advanced explaining the adsorption properties of calcein thin films taking into account their chemical structure and peculiarities of molecular packing. The possibility of application of thermally sputtered calcein films in sensing technique is discussed. Copyright (c) 2010 Elsevier B.V. All rights reserved.

  18. ZIF-8 Membranes with Improved Reproducibility Fabricated from Sputter-Coated ZnO/Alumina Supports

    KAUST Repository

    Yu, Jian

    2015-11-10

    Zeolitic imidazolate framework-8 (ZIF-8) membrane has shown great potential for propylene/propane separation based on molecular sieving mechanism. Although diverse synthesis strategies were applied to prepare ZIF-8 membranes, it is still a challenge for reproducible fabrication of high-quality membranes. In this study, high-quality ZIF-8 membranes were prepared through hydrothermal synthesis under the partial self-conversion of sputter-coated ZnO layer on porous α-alumina supports. The reproducibility was significantly improved, compared with that from sol-gel coated ZnO layer, due to the highly controllable sputtering deposition of ZnO precursor. The relationship between the quality of as-synthesized membrane and amount of deposited ZnO was also determined. The effect of pressure drop in C3H6/C3H8 separation on separating performance was also examined.

  19. The triel bond: a potential force for tuning anion-π interactions

    Science.gov (United States)

    Esrafili, Mehdi D.; Mousavian, Parisasadat

    2018-02-01

    Using ab-initio calculations, the mutual influence between anion-π and B···N or B···C triel bond interactions is investigated in some model complexes. The properties of these complexes are studied by molecular electrostatic potential, noncovalent interaction index, quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. According to the results, the formation of B···N or B···C triel bond interactions in the multi-component systems makes a significant shortening of anion-π distance. Such remarkable variation in the anion-π distances has not been reported previously. The strengthening of the anion-π bonding in the multi-component systems depend significantly on the nature of the anion, and it becomes larger in the order Br- > Cl- > F-. The parameters derived from the QTAIM and NBO methodologies are used to study the mechanism of the cooperativity between the anion-π and triel bond interactions in the multi-component complexes.

  20. Matted-fiber divertor tagets for sputter resistance

    International Nuclear Information System (INIS)

    Gierszewski, P.J.; Todreas, N.E.; Mikic, B.; Yang, T.F.

    1981-06-01

    Reductions in net sputtering yields can be obtained by altering the surface topography to maximize redeposition of sputtered atoms. A simple analysis is used to indicate a potential reduction by a factor of 2 to 5 for matted fiber divertor targets, relatively independent of incident, reflected and sputtered atom distributions. The fiber temperature is also shown to be acceptable, even up to 10 MW/m 2 , for reasonably combinations of materials, fiber diameter and fiber spacing

  1. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar; Hadjichristidis, Nikolaos; Mays, Jimmy

    2015-01-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization

  2. Long-range intramolecular electron transfer in aromatic radical anions and binuclear transition metal complexes

    DEFF Research Database (Denmark)

    Kuznetsov, A. M.; Ulstrup, Jens

    1981-01-01

    Intramolecular electron transfer (ET) over distances up to about 10 Å between states in which the electron is localized on donor and acceptor groups by interaction with molecular or external solvent nuclear motion occurs, in particular, in two classes of systems. The excess electron in anionic ra...

  3. A Study of Picosecond Dehalogenation of Chlorobenzene Anions in Liquids of Positronium Inhibition Measurements

    DEFF Research Database (Denmark)

    Wikander, G.; Mogensen, O. E.

    1982-01-01

    on intramolecular electron transfer with subsequent dehalogenation of the molecular anion on a picosecond timescale. The divergence in inhibitor efficiency obtained for the chlorobenzenes when dissolved in aromatic solvents compared to the same solutes when dissolved in a saturated alkane appears most probably...

  4. Organic anion exudation by ectomycorrhizal fungi and Pinus sylvestris in response to nutrient deficiences

    NARCIS (Netherlands)

    Schöll, van L.; Hoffland, E.; Breemen, van N.

    2006-01-01

    Low molecular weight organic anions (LMWOA) can enhance weathering of mineral grains. We tested the hypothesis that ectomycorrhizal (EcM) fungi and tree seedlings increase their exudation of LMWOA when supply of magnesium, potassium and phosphorus is low to enhance the mobilization of Mg, K and P

  5. Atomic-scale structure and electrostatics of anionic palmitoyloleoylphosphatidylglycerol lipid bilayers with Na+ counterions

    NARCIS (Netherlands)

    Zhao, W.; Róg, T.; Gurtovenko, A.A.; Vattulainen, I.; Karttunen, M.E.J.

    2007-01-01

    Anionic palmitoyloleoylphosphatidylglycerol (POPG) is one of the most abundant lipids in nature, yet its atomic-scale properties have not received significant attention. Here we report extensive 150-ns molecular dynamics simulations of a pure POPG lipid membrane with sodium counterions. It turns out

  6. Sputtering materials for VLSI and thin film devices

    CERN Document Server

    Sarkar, Jaydeep

    2010-01-01

    An important resource for students, engineers and researchers working in the area of thin film deposition using physical vapor deposition (e.g. sputtering) for semiconductor, liquid crystal displays, high density recording media and photovoltaic device (e.g. thin film solar cell) manufacturing. This book also reviews microelectronics industry topics such as history of inventions and technology trends, recent developments in sputtering technologies, manufacturing steps that require sputtering of thin films, the properties of thin films and the role of sputtering target performance on overall p

  7. Computer simulation of the self-sputtering of uranium

    International Nuclear Information System (INIS)

    Robinson, M.T.

    1983-01-01

    The sputtering of polycrystalline α-uranium by uranium ions of energies below 10 keV has been studied in the binary collision approximation using the computer simulation program marlowe. Satisfactory agreement of the computed sputtering yields with the small amount of available experimental data was achieved using the Moliere interatomic potential, a semilocal inelastic loss function, and a planar surface binding barrier, all with conventional parameters. The model is used to discuss low energy sputtering processes and the energy and angular distributions of the reflected primaries and the sputtered target particles

  8. Sputtering induced surface composition changes in copper-palladium alloys

    International Nuclear Information System (INIS)

    Sundararaman, M.; Sharma, S.K.; Kumar, L.; Krishnan, R.

    1981-01-01

    It has been observed that, in general, surface composition is different from bulk composition in multicomponent materials as a result of ion beam sputtering. This compositional difference arises from factors like preferential sputtering, radiation induced concentration gradients and the knock-in effect. In the present work, changes in the surface composition of copper-palladium alloys, brought about by argon ion sputtering, have been studied using Auger electron spectroscopy. Argon ion energy has been varied from 500 eV to 5 keV. Enrichment of palladium has been observed in the sputter-altered layer. The palladium enrichment at the surface has been found to be higher for 500 eV argon ion sputtering compared with argon ion sputtering at higher energies. Above 500 eV, the surface composition has been observed to remain the same irrespective of the sputter ion energy for each alloy composition. The bulk composition ratio of palladium to copper has been found to be linearly related to the sputter altered surface composition ratio of palladium to copper. These results are discussed on the basis of recent theories of alloy sputtering. (orig.)

  9. Data compilation of angular distributions of sputtered atoms

    International Nuclear Information System (INIS)

    Yamamura, Yasunori; Takiguchi, Takashi; Tawara, Hiro.

    1990-01-01

    Sputtering on a surface is generally caused by the collision cascade developed near the surface. The process is in principle the same as that causing radiation damage in the bulk of solids. Sputtering has long been regarded as an undesirable dirty effect which destroys the cathodes and grids in gas discharge tubes or ion sources and contaminates plasma and the surrounding walls. However, sputtering is used today for many applications such as sputter ion sources, mass spectrometers and the deposition of thin films. Plasma contamination and the surface erosion of first walls due to sputtering are still the major problems in fusion research. The angular distribution of the particles sputtered from solid surfaces can possibly provide the detailed information on the collision cascade in the interior of targets. This report presents a compilation of the angular distribution of sputtered atoms at normal incidence and oblique incidence in the various combinations of incident ions and target atoms. The angular distribution of sputtered atoms from monatomic solids at normal incidence and oblique incidence, and the compilation of the data on the angular distribution of sputtered atoms are reported. (K.I.)

  10. Probing Intermolecular Electron Delocalization in Dimer Radical Anions by Vibrational Spectroscopy

    International Nuclear Information System (INIS)

    Mani, Tomoyasu; Brookhaven National Laboratory; Grills, David C.

    2017-01-01

    Delocalization of charges is one of the factors controlling charge transport in conjugated molecules. It is considered to play an important role in the performance of a wide range of molecular technologies, including organic solar cells and organic electronics. Dimerization reactions are well-suited as a model to investigate intermolecular spatial delocalization of charges. And while dimerization reactions of radical cations are well investigated, studies on radical anions are still scarce. Upon dimerization of radical anions with neutral counterparts, an electron is considered to delocalize over the two molecules. By using time-resolved infrared (TRIR) detection coupled with pulse radiolysis, we show that radical anions of 4-n-hexyl-4'-cyanobiphenyl (6CB) undergo such dimerization reactions, with an electron equally delocalized over the two molecules. We have recently demonstrated that nitrile ν(C≡N) vibrations respond to the degree of electron localization of nitrile-substituted anions: we can quantify the changes in the electronic charges from the neutral to the anion states in the nitriles by monitoring the ν(C≡N) IR shifts. In the first part of this article, we show that the sensitivity of the ν(C≡N) IR shifts does not depend on solvent polarity. In the second part, we describe how probing the shifts of the nitrile IR vibrational band unambiguously confirms the formation of dimer radical anions, with K dim = 3 × 10 4 M –1 . IR findings are corroborated by electronic absorption spectroscopy and electronic structure calculations. We find that the presence of a hexyl chain and the formation of π–π interactions are both crucial for dimerization of radical anions of 6CB with neutral 6CB. Our study provides clear evidence of spatial delocalization of electrons over two molecular fragments.

  11. Photoelectron spectroscopy of the 6-azauracil anion.

    Science.gov (United States)

    Chen, Jing; Buonaugurio, Angela; Dolgounitcheva, Olga; Zakrzewski, V G; Bowen, Kit H; Ortiz, J V

    2013-02-14

    We report the photoelectron spectrum of the 6-azauracil anion. The spectrum is dominated by a broad band exhibiting a maximum at an electron binding energy (EBE) of 1.2 eV. This spectral pattern is indicative of a valence anion. Our calculations were carried out using ab initio electron propagator and other many-body methods. Comparison of the anion and corresponding neutral of 6-azauracil with those of uracil shows that substituting a nitrogen atom for C-H at the C6 position of uracil gives rise to significant changes in the electronic structure of 6-azauracil versus that of uracil. The adiabatic electron affinity (AEA) of the canonical 6-azauracil tautomer is substantially larger than that of canonical uracil. Among the five tautomeric, 6-azauracil anions studied computationally, the canonical structure was found to be the most stable. The vertical detachment energies (VDE) of the canonical, valence-bound anion of 6-azauracil and its closest "very-rare" tautomer have been calculated. Electron propagator calculations on the canonical anion yield a VDE value that is in close agreement with the experimentally determined VDE value of 1.2 eV. The AEA value of 6-azauracil, assessed at the CCSD(T) level of theory to be 0.5 eV, corresponds with the EBE value of the onset of the experimental spectrum.

  12. Vibrational Spectroscopy of Cation and Anion Channelrhodopsins

    Science.gov (United States)

    Yi, Adrian S.

    Optogenetics is a technique to control and monitor cell activity with light by expression of specific microbial rhodopsins. Cation channelrhodopsins (CCRs) and anion channelrhodopsins (ACRs) have been demonstrated to activate and silence cell activity, respectively. In this dissertation, the molecular mechanisms of two channelrhodopsins are studied: a CCR from Chlamydomonas augustae (CaChR1) and an ACR from Guillardia theta (GtACR1). The recently discovered GtACR1is especially interesting, as it achieves neural silencing with 1/1000th of the light intensity compared to previous microbial rhodopsin silencing ion pumps. Static and time-resolved resonance Raman, FTIR difference, and UV-visible spectroscopies were utilized in addition to various biochemical and genetic techniques to explore the molecular mechanisms of these channelrhodopsins. In CaChR1, Glu169 and Asp299 residues are located nearby the Schiff base (SB) similar to the homologous residues Asp85 and Asp212, which exist in an ionized state in unphotolyzed bacteriorhodopsin (BR) and play a key role in proton pumping. We observe significant changes in the protonation states of the SB, Glu169, and Asp299 of CaChR1 leading up to the open-channel P2 state, where all three groups exist in a charge neutral state. This unusual charge neutrality along with the position of these groups in the CaChR1 ion channel suggests that charge neutrality plays an important role in cation gating and selectivity in these low efficiency CCRs. Significant differences exist in the photocycle and protonation/hydrogen bonding states of key residues inGtACR1compared to BR and CaChR1. Resonance Raman studies reveal that in the unphotolyzed state of GtACR1, residues Glu68, Ser97 (BR Asp85 homolog), and Asp234 (BR Asp212 homolog) located near the SB exist in charge neutral states. Furthermore, upon K formation, these residues do not change their protonation states. At room temperature, a slow decay of the red-shifted K intermediate is

  13. Refractive properties of imidazolium ionic liquids with alanine anion [C n mim][Ala] ( n = 2, 3, 4, 5, 6)

    Science.gov (United States)

    Zhou, Cai-bin; Li, Jing; Yi, Zhe; Ai, Hong-jun

    2017-10-01

    Imidazolium ionic liquids with alanine anion, [C n mim][Ala] ( n = 2, 3, 4, 5, 6), were prepared and characterized. The standard addition method was used to measure refractivity of the synthesized ionic liquids in order to eliminate the effect of water traces in the ionic liquids. The molar refraction and molecular polarizability were also calculated by Lorentz-Lorenz's method. Using liner extrapolation, the semiempirical estimation method for optical properties of other ionic liquids with amino acid anions was established.

  14. Deposition and characterization of sputtered hexaboride coatings

    International Nuclear Information System (INIS)

    Waldhauser, W.

    1996-06-01

    Hexaborides of the rare-earth elements ReB 6 are potential materials for cathode applications since they combine properties such as low work function, good electrical conductivity, high melting point as well as low volatility at high temperatures. Due to their high hardness and colorations ranging from blue to purple these compounds are also considered for applications to coatings for decoration of consumer products. At present, either rods of sintered LaB 6 or single LaB 6 crystals are indirectly heated to induce emission. In this workboride coatings were deposited onto various substrates employing non-reactive magnetron sputtering from LaB 6 , CeB 6 , SmB 6 and YB 6 targets. Coatings deposited were examined using scanning electron microscopy, X-ray diffraction, electron probe microanalysis. Vickers microhardness, colorimeter and spectroscopic ellipsometry measurements. Electron emission characteristics of the coatings were studied by the thermionic emission and the contact potential method. After optimization of the sputtering parameters fine-columnar or partially amorphous films with atomic ratios of boron to metal in the order of 5 to 7.5 were obtained. The tendency to form the corresponding hexaboride phase decreases from LaB 6 , CeB 6 and SmB 6 to YB 6 . The work function was measured to be in the range of 2.6 to 3.3 eV. Vickers microhardness values lie between 1500 and 2000 HVO.01. LaB 6 coatings showed the most pronounced visual color impression corresponding to dark violet. The results obtained indicate that sputtered hexaboride films are well suited for decorative and thermionic applications. (author)

  15. Reactive sputter deposition of boron nitride

    International Nuclear Information System (INIS)

    Jankowski, A.F.; Hayes, J.P.; McKernan, M.A.; Makowiecki, D.M.

    1995-10-01

    The preparation of fully dense, boron targets for use in planar magnetron sources has lead to the synthesis of Boron Nitride (BN) films by reactive rf sputtering. The deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are characterized for composition using Auger electron spectroscopy, for chemical bonding using Raman spectroscopy and for crystalline structure using transmission electron microscopy. The deposition conditions are established which lead to the growth of crystalline BN phases. In particular, the growth of an adherent cubic BN coating requires 400--500 C substrate heating and an applied -300 V dc bias

  16. Development of the sputter coater for hotcell

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Yong Bum; Kwon, H. M.; Chun, Y. B.; Yang, Y. S.; Joo, J. S.; Jang, N. M

    2007-05-15

    In last december, the Wavelength Dispersive Spectroscopy (WDS) was installed on the shielded SEM of PIEF, KAERI. Before the first major WDS analysis service at the end of 2007, one among the prior technologies, the hot-cell sputter coater was remodelled from a commercial product and set up inside the glove box. This report describes effects of a coating layer on quantitative analysis, the remodelling of a coater suited to hot-cell, and the performance test of the remodelled coater. Also, written in 1998 was revised and appended to the report.

  17. Thermal conductivity of sputtered amorphous Ge films

    International Nuclear Information System (INIS)

    Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka

    2014-01-01

    We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids

  18. Putting the pieces together: a crystal clear window into CLC anion channel regulation.

    Science.gov (United States)

    Strange, Kevin

    2011-01-01

    CLC anion transport proteins function as Cl (-) channels and Cl (-) /H (+) exchangers and are found in all major groups of life including archaebacteria. Early electrophysiological studies suggested that CLC anion channels have two pores that are opened and closed independently by a "fast" gating process operating on a millisecond timescale, and a "common" or "slow" gate that opens and closes both pores simultaneously with a timescale of seconds (Figure 1A). Subsequent biochemical and molecular experiments suggested that CLC channels/transporters are homodomeric proteins ( 1-3) .

  19. Communication: Remarkable electrophilicity of the oxalic acid monomer: An anion photoelectron spectroscopy and theoretical study

    International Nuclear Information System (INIS)

    Buonaugurio, Angela; Graham, Jacob; Buytendyk, Allyson; Bowen, Kit H.; Ryder, Matthew R.; Gutowski, Maciej; Keolopile, Zibo G.; Haranczyk, Maciej

    2014-01-01

    Our experimental and computational results demonstrate an unusual electrophilicity of oxalic acid, the simplest dicarboxylic acid. The monomer is characterized by an adiabatic electron affinity and electron vertical detachment energy of 0.72 and 1.08 eV (±0.05 eV), respectively. The electrophilicity results primarily from the bonding carbon-carbon interaction in the singly occupied molecular orbital of the anion, but it is further enhanced by intramolecular hydrogen bonds. The well-resolved structure in the photoelectron spectrum is reproduced theoretically, based on Franck-Condon factors for the vibronic anion → neutral transitions

  20. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    International Nuclear Information System (INIS)

    Bowman-James, K.; Wilson, G.; Moyer, B. A.

    2004-01-01

    This project involves the design and synthesis of receptors for oxoanions of environmental importance, including emphasis on high level and low activity waste. Target anions have included primarily oxoanions and a study of the basic concepts behind selective binding of target anions. A primary target has been sulfate because of its deleterious influence on the vitrification of tank wastes

  1. Ion source with radiofrequency mass filter for sputtering purposes

    International Nuclear Information System (INIS)

    Sielanko, J.; Sowa, M.

    1990-01-01

    The Kaufman ion source with radiofrequency mass filter is described. The construction as well as operating characteristics of ion source are presented. The arrangement is suitable for range distribution measurements of implanted layers, where the sputtering rate has to be constant over the wide range of sputtering time. 4 figs., 17 refs. (author)

  2. Low-dose effects in the sputtering of evaporated films

    International Nuclear Information System (INIS)

    Florio, A.R.O.; Alonso, E.V.; Baragiola, R.A.; Ferron, J.

    1983-01-01

    We report measurements of the dose dependence of the sputtering of evaporated films by 30 keV ions under UHV. An initial (sub-monolayer) enhanced sputtering is attributed to the removal of weakly bound atoms; this enhancement does not depend on the incidence angle of the projectile. (author)

  3. Low-dose effects in the sputtering of evaporated films

    Energy Technology Data Exchange (ETDEWEB)

    Florio, A.R.O.; Alonso, E.V.; Baragiola, R.A.; Ferron, J. (Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico Bariloche)

    1983-05-01

    We report measurements of the dose dependence of the sputtering of evaporated films by 30 keV ions under UHV. An initial (sub-monolayer) enhanced sputtering is attributed to the removal of weakly bound atoms; this enhancement does not depend on the incidence angle of the projectile.

  4. Formation of large clusters during sputtering of silver

    International Nuclear Information System (INIS)

    Staudt, C.; Heinrich, R.; Wucher, A.

    2000-01-01

    We have studied the formation of polyatomic clusters during sputtering of metal surfaces by keV ion bombardment. Both positively charged (secondary cluster ions) and neutral clusters have been detected in a time-of-flight mass spectrometer under otherwise identical experimental conditions, the sputtered neutrals being post-ionized by single photon absorption using a pulsed 157 nm VUV laser beam. Due to the high achievable laser intensity, the photoionization of all clusters could be saturated, thus enabling a quantitative determination of the respective partial sputtering yields. We find that the relative yield distributions of sputtered clusters are strongly correlated with the total sputtering yield in a way that higher yields lead to higher abundances of large clusters. By using heavy projectile ions (Xe + ) in connection with bombarding energies up to 15 keV, we have been able to detect sputtered neutral silver clusters containing up to about 60 atoms. For cluster sizes above 40 atoms, doubly charged species are shown to be produced in the photoionization process with non-negligible efficiency. From a direct comparison of secondary neutral and ion yields, the ionization probability of sputtered clusters is determined as a function of the cluster size. It is demonstrated that even the largest silver clusters are still predominantly sputtered as neutrals

  5. Sputtering of Ge(001): transition between dynamic scaling regimes

    DEFF Research Database (Denmark)

    Smilgies, D.-M.; Eng, P.J.; Landemark, E.

    1997-01-01

    We have studied the dynamic behavior of the Ge(001) surface during sputtering in situ and in real time using synchrotron X-ray diffraction. We find two dynamic regimes as a function of surface temperature and sputter current which are separated by a sharp transition. The boundary between these two...

  6. Sputtering of Thick Deuterium Films by KeV Electrons

    DEFF Research Database (Denmark)

    Thestrup Nielsen, Birgitte; Svendsen, Winnie Edith; Schou, Jørgen

    1994-01-01

    Sputtering of thick films of solid deuterium up to several μm by keV electrons is reported for the first time. The sputtering yield increases within a narrow range of thicknesses around 1.6 μm by about 2 orders of magnitude for 1.5 keV electrons. A similar behavior has not been observed for ion...

  7. RF sputtering: A viable tool for MEMS fabrication

    Indian Academy of Sciences (India)

    being prepared by RF sputtering and their application in MEMS being explored. ... crystallographic properties were evaluated using XRD analysis (CuKα radiation ..... Bhatt V, Pal P, Chandra S 2005 Feasibility study of RF sputtered ZnO film for ...

  8. Hydrogen Bond Dynamics in Aqueous Solutions: Ab initio Molecular ...

    Indian Academy of Sciences (India)

    Rate equation for the decay of CHB(t) · Definition of Hydrogen Bonds · Results of Molecular Dynamics · Dynamics of anion-water and water-water hydrogen bonds · Structural relaxation of anion-water & water-water H-bonds · Ab initio Molecular Dynamics : · Slide 14 · Dynamics of hydrogen bonds : CPMD results · Slide 16.

  9. RHEED oscillations in spinel ferrite epitaxial films grown by conventional planar magnetron sputtering

    Science.gov (United States)

    Ojima, T.; Tainosho, T.; Sharmin, S.; Yanagihara, H.

    2018-04-01

    Real-time in situ reflection high energy electron diffraction (RHEED) observations of Fe3O4, γ-Fe2O3, and (Co,Fe)3O4 films on MgO(001) substrates grown by a conventional planar magnetron sputtering was studied. The change in periodical intensity of the specular reflection spot in the RHEED images of three different spinel ferrite compounds grown by two different sputtering systems was examined. The oscillation period was found to correspond to the 1/4 unit cell of each spinel ferrite, similar to that observed in molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) experiments. This suggests that the layer-by-layer growth of spinel ferrite (001) films is general in most physical vapor deposition (PVD) processes. The surfaces of the films were as flat as the surface of the substrate, consistent with the observed layer-by-layer growth process. The observed RHEED oscillation indicates that even a conventional sputtering method can be used to control film thickness during atomic layer depositions.

  10. RHEED oscillations in spinel ferrite epitaxial films grown by conventional planar magnetron sputtering

    Directory of Open Access Journals (Sweden)

    T. Ojima

    2018-04-01

    Full Text Available Real-time in situ reflection high energy electron diffraction (RHEED observations of Fe3O4, γ-Fe2O3, and (Co,Fe3O4 films on MgO(001 substrates grown by a conventional planar magnetron sputtering was studied. The change in periodical intensity of the specular reflection spot in the RHEED images of three different spinel ferrite compounds grown by two different sputtering systems was examined. The oscillation period was found to correspond to the 1/4 unit cell of each spinel ferrite, similar to that observed in molecular beam epitaxy (MBE and pulsed laser deposition (PLD experiments. This suggests that the layer-by-layer growth of spinel ferrite (001 films is general in most physical vapor deposition (PVD processes. The surfaces of the films were as flat as the surface of the substrate, consistent with the observed layer-by-layer growth process. The observed RHEED oscillation indicates that even a conventional sputtering method can be used to control film thickness during atomic layer depositions.

  11. Sputtering from swift-ion trails in LiF: A hybrid PIC/MD simulation

    Energy Technology Data Exchange (ETDEWEB)

    Cherednikov, Yaroslav; Sun, Si Neng; Urbassek, Herbert M., E-mail: urbassek@rhrk.uni-kl.de

    2013-11-15

    We model the sputtering of a LiF crystal induced by swift-ion impact. The impinging ion creates a trail of doubly ionized F{sup +} ions, while simultaneously the corresponding electrons are set free. Ions move according to molecular dynamics, while excited electrons are treated by a particle-in-cell scheme. We treat the recombination time of electrons as a free parameter in our model. We find that the energy distribution of sputtered ions consists of 2 groups: a low-energy group centered at <1 eV, and a high-energy group at 7–8 eV. Fast ions (mainly Li{sup +}) are emitted early; these charge the surface negatively. Later, larger cluster ions and also neutral LiF molecules are emitted. Emission occurs at low angles to the surface normal. A jet along the normal direction can be observed, which is due to the electric field building up at the track surface. With increasing recombination time, processes are colder; sputtering decreases and the non-thermal jet structure becomes stronger.

  12. Modelling of low energy ion sputtering from oxide surfaces

    International Nuclear Information System (INIS)

    Kubart, T; Nyberg, T; Berg, S

    2010-01-01

    The main aim of this work is to present a way to estimate the values of surface binding energy for oxides. This is done by fitting results from the binary collisions approximation code Tridyn with data from the reactive sputtering processing curves, as well as the elemental composition obtained from x-ray photoelectron spectroscopy (XPS). Oxide targets of Al, Ti, V, Nb and Ta are studied. The obtained surface binding energies are then used to predict the partial sputtering yields. Anomalously high sputtering yield is observed for the TiO 2 target. This is attributed to the high sputtering yield of Ti lower oxides. Such an effect is not observed for the other studied metals. XPS measurement of the oxide targets confirms the formation of suboxides during ion bombardment as well as an oxygen deficient surface in the steady state. These effects are confirmed from the processing curves from the oxide targets showing an elevated sputtering rate in pure argon.

  13. Cytotoxic mechanisms of hydrosulfide anion and cyanide anion in primary rat hepatocyte cultures

    International Nuclear Information System (INIS)

    Thompson, Rodney W.; Valentine, Holly L.; Valentine, William M.

    2003-01-01

    Hydrogen sulfide and hydrogen cyanide are known to compromise mitochondrial respiration through inhibition of cytochrome c oxidase and this is generally considered to be their primary mechanism of toxicity. Experimental studies and the efficiency of current treatment protocols suggest that H 2 S may exert adverse physiological effects through additional mechanisms. To evaluate the role of alternative mechanisms in H 2 S toxicity, the relative contributions of electron transport inhibition, uncoupling of mitochondrial respiration, and opening of the mitochondrial permeability transition pore (MPTP) to hydrosulfide and cyanide anion cytotoxicity in primary hepatocyte cultures were examined. Supplementation of hepatocytes with the glycolytic substrate, fructose, rescued hepatocytes from cyanide anion induced toxicity, whereas fructose supplementation increased hydrosulfide anion toxicity suggesting that hydrosulfide anion may compromise glycolysis in hepatocytes. Although inhibitors of the MPTP opening were protective for hydrosulfide anion, they had no effect on cyanide anion toxicity, consistent with an involvement of the permeability transition pore in hydrosulfide anion toxicity but not cyanide anion toxicity. Exposure of isolated rat liver mitochondria to hydrosulfide did not result in large amplitude swelling suggesting that if H 2 S induces the permeability transition it does so indirectly through a mechanism requiring other cellular components. Hydrosulfide anion did not appear to be an uncoupler of mitochondrial respiration in hepatocytes based upon the inability of oligomycin and fructose to protect hepatocytes from hydrosulfide anion toxicity. These findings support mechanisms additional to inhibition of cytochrome c oxidase in hydrogen sulfide toxicity. Further investigations are required to assess the role of the permeability transition in H 2 S toxicity, determine whether similar affects occur in other cell types or in vivo and evaluate whether this may

  14. Ca2+ and Mg2+-enhanced reduction of arsenazo III to its anion free radical metabolite and generation of superoxide anion by an outer mitochondrial membrane azoreductase.

    Science.gov (United States)

    Moreno, S N; Mason, R P; Docampo, R

    1984-12-10

    At the concentrations usually employed as a Ca2+ indicator, arsenazo III underwent a one-electron reduction by rat liver mitochondria to produce an azo anion radical as demonstrated by electron-spin resonance spectroscopy. Either NADH or NADPH could serve as a source of reducing equivalents for the production of this free radical by intact rat liver mitochondria. Under aerobic conditions, addition of arsenazo III to rat liver mitochondria produced an increase in electron flow from NAD(P)H to molecular oxygen, generating superoxide anion. NAD(P)H generated from endogenous mitochondrial NAD(P)+ by intramitochondrial reactions could not be used for the NAD(P)H azoreductase reaction unless the mitochondria were solubilized by detergent or anaerobiosis. In addition, NAD(P)H azoreductase activity was higher in the crude outer mitochondrial membrane fraction than in mitoplasts and intact mitochondria. The steady-state concentration of the azo anion radical and the arsenazo III-stimulated cyanide-insensitive oxygen consumption were enhanced by calcium and magnesium, suggesting that, in addition to an enhanced azo anion radical-stabilization by complexation with the metal ions, enhanced reduction of arsenazo III also occurred. Accordingly, addition of cations to crude outer mitochondrial membrane preparations increased arsenazo III-stimulated cyanide-insensitive O2 consumption, H2O2 formation, and NAD(P)H oxidation. Antipyrylazo III was much less effective than arsenazo III in increasing superoxide anion formation by rat liver mitochondria and gave a much weaker electron spin resonance spectrum of an azo anion radical. These results provide direct evidence of an azoreductase activity associated with the outer mitochondrial membrane and of a stimulation of arsenazo III reduction by cations.

  15. Thermal conductivities of thin, sputtered optical films

    International Nuclear Information System (INIS)

    Henager, C.H. Jr.; Pawlewicz, W.T.

    1991-05-01

    The normal component of the thin film thermal conductivity has been measured for the first time for several advanced sputtered optical materials. Included are data for single layers of boron nitride (BN), aluminum nitride (AIN), silicon aluminum nitride (Si-Al-N), silicon aluminum oxynitride (Si-Al-O-N), silicon carbide (SiC), and for dielectric-enhanced metal reflectors of the form Al(SiO 2 /Si 3 N 4 ) n and Al(Al 2 O 3 /AIN) n . Sputtered films of more conventional materials like SiO 2 , Al 2 O 3 , Ta 2 O 5 , Ti, and Si have also been measured. The data show that thin film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or very fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film/substrate interface contribution is presented

  16. Evolution of film temperature during magnetron sputtering

    International Nuclear Information System (INIS)

    Shaginyan, L.R.; Han, J.G.; Shaginyan, V.R.; Musil, J.

    2006-01-01

    We report on the results of measurements of the temperature T F surf which developed on the surface of films deposited by magnetron sputtering of chromium and copper targets on cooling and non-cooling silicon substrates. The T F surf and substrate temperature (T s ) were simultaneously measured using high-resolution IR camera and thermocouple, respectively. We revealed that the T F surf steeply grows, keeps constant when it achieves saturation level, and rapidly drops to the value of the T s after stopping the deposition. At the same time, the T s either does not change for the case of cooling substrate or increases to a certain level for noncooling substrate. However, in both cases the T s remains several times lower than the T F surf . The T F surf is proportional to the flux of energy delivered to the growth surface by sputtered atoms and other fast particles, weakly depends on the depositing metal and can achieve several hundreds of deg. C. This phenomenon is explained by a model assuming formation of a hot thin surface layer (HTSL) on the top of the growing film, which exists only during film deposition and exhibits extremely low thermal conductivity. Due to this unique property the temperature T F surf of HTSL is several times higher than the T s . Variations in the T F surf fairly correlate with structure changes of Cr films along thickness investigated in detail previously

  17. Experimental and analytical study of the sputtering phenomena

    International Nuclear Information System (INIS)

    Howard, P.A.

    1976-03-01

    One form of the sputtering phenomena, the heat-transfer process that occurs when an initially hot vertical surface is cooled by a falling liquid film, was examined from a new experimental approach. The sputtering front is the lowest wetted position on the vertical surface and is characterized by a short region of intense nucleate boiling. The sputtering front progresses downward at nearly a constant rate, the surface below the sputtering front being dry and almost adiabatic. This heat-transfer process is of interest in the analysis of some of the performance aspects of emergency core-cooling systems of light-water reactors. An experimental apparatus was constructed to examine the heat-transfer characteristics of a sputtering front. In the present study, a heat source of sufficient intensity was located immediately below the sputtering front, which prevented its downward progress, thus permitting detailed measurements of steady-state surface temperatures throughout a sputtering front. Experimental evidence showed the sputtering front to correspond to a critical heat-flux (CHF) phenomenon. Data were obtained with water flow rates of 350-1600 lb/sub m//hr-ft and subcoolings of 40-140 0 F on a 3 / 8 -in. solid copper rod at 1 atm. A two-dimensional analytical model was developed to describe a stationary sputtering front where the wet-dry interface corresponds to a CHF phenomena and the dry zone is adiabatic. This model is nonlinear because of the temperature dependence of the heat-transfer coefficient in the wetted region and has yielded good agreement with data. A simplified one-dimensional approximation was developed which adequately describes these data. Finally, by means of a coordinate transformation and additional simplifying assumptions, this analysis was extended to analyze moving sputtering fronts, and reasonably good agreement with reported data was shown

  18. Advanced capabilities and applications of a sputter-RBS system

    International Nuclear Information System (INIS)

    Brijs, B.; Deleu, J.; Beyer, G.; Vandervorst, W.

    1999-01-01

    In previous experiments, sputter-RBS 1 has proven to be an ideal tool to study the interaction of low energy ions. This contribution employs the same methodology to identify surface contamination induced during sputtering and to the determine absolute sputter yields. In the first experiment ERDA analysis was used to study the evolution of Hydrogen contamination during sputter-RBS experiments. Since the determination of Hydrogen concentration in very thin near surface layers is frequently limited by the presence of a strong surface peak of Hydrogen originating from adsorbed contamination of the residual vacuum, removal of this contamination would increase the sensitivity for Hydrogen detection in the near sub surface drastically. Therefore low energy (12 keV) Argon sputtering was used to remove the Hydrogen surface peak. However enhanced Hydrogen adsorption was observed related to the Ar dose. This experiment shows that severe vacuum conditions and the use of high current densities/sputter yields are a prerequisite for an efficient detection of Hydrogen in the near surface layers. In the second experiment, an attempt was made to determine the sputter yield of Cu during low energy (12 keV) Oxygen bombardment. In order to determine the accumulated dose of the low energy ion beam, a separate Faraday cup in combination with a remote controlled current have been added to the existing sputter-RBS set-up. Alternating sputtering and RBS analysis seem to be an adequate tool for the determination of the absolute sputter yield of Cu and this as well in the as under steady state conditions

  19. Sputtering effect of low-energy ions on biological target: The analysis of sputtering product of urea and capsaicin

    International Nuclear Information System (INIS)

    Zhang, Lili; Xu, Xue; Wu, Yuejin

    2013-01-01

    Sputtering is a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic particles. Recent years, ion implantation was successfully applied to biological research based on the fragments sputtering and form open paths in cell structure caused by ion sputtering. In this study, we focused on urea and chilli pepper pericarp samples implanted with N + and Ar + ions. To investigate the sputtering effect, we designed a collecting unit containing a disk sample and a glass pipe. The urea content and capsaicin content recovered from glass pipes were adopted to represent the sputtering product. The result of urea showed that the sputtering effect is positively correlated with the ion energy and dose, also affected by the ion type. The result of capsaicin was different from that of urea at 20 keV and possibly due to biological complex composition and structure. Therefore the sputtering yield depended on both the parameters of incident ions and the state of target materials. The sputtering yield of urea was also simulated by computational method achieved through the TRIM program. The trajectories of primary and recoiled atoms were calculated on the basis of the binary collision approximation using Monte Carlo method. The experimental results were much higher than the calculated results. The possible explanation is that in the physical model the target were assumed as a disordered lattice and independent atoms, which is much less complicated than that of the biological models

  20. On a relationship between the geometry of cones on sputtered surfaces and the angular dependence of sputtered yields

    International Nuclear Information System (INIS)

    Chadderton, L.T.

    1977-01-01

    It is widely believed that the phenomenon responsible for the familiar peak in the angular dependence of sputtered yields also gives rise to characteristic semiangles α of conical protruberances on sputtered surfaces. It is shown that α corresponds to the process giving rise to the minimum rather than the maximum. No accurate measurements of the minimum have yet been made. (Auth.)

  1. Solvation of monovalent anions in formamide and methanol: Parameterization of the IEF-PCM model

    International Nuclear Information System (INIS)

    Boees, Elvis S.; Bernardi, Edson; Stassen, Hubert; Goncalves, Paulo F.B.

    2008-01-01

    The thermodynamics of solvation for a series of monovalent anions in formamide and methanol has been studied using the polarizable continuum model (PCM). The parameterization of this continuum model was guided by molecular dynamics simulations. The parameterized PCM model predicts the Gibbs free energies of solvation for 13 anions in formamide and 16 anions in methanol in very good agreement with experimental data. Two sets of atomic radii were tested in the definition of the solute cavities in the PCM and their performances are evaluated and discussed. Mean absolute deviations of the calculated free energies of solvation from the experimental values are in the range of 1.3-2.1 kcal/mol

  2. Gas-Phase Reactivity of Microsolvated Anions

    DEFF Research Database (Denmark)

    Thomsen, Ditte Linde

    the gas-phase α-effect. The experimental studies are performed by means of the flowing after glow selected ion flow tube technique, and these are supplemented by electronic structure calculations. The α-nucleophile employed is the microsolvated hydrogen peroxide anion whose reactivity is compared......Gas-phase studies of ion-molecule reactions shed light on the intrinsic factors that govern reactivity; and even solvent effects can be examined in the gasphase environment by employing microsolvated ions. An area that has received considerable attention with regard to the interplay between...... to that of a series of microsolvated oxygen centered anions. The association of the nucleophiles with a single water or methanol molecule allows the α-effect to be observed in the SN2 reaction with methyl chloride; this effect was not apparent in the reactions of the unsolvated anions. The results suggest...

  3. New borohydride anion B6H7-

    International Nuclear Information System (INIS)

    Kuznetsov, I.Yu.; Vinitskij, D.M.; Solntsev, K.A.

    1985-01-01

    The [Ni(Bipy) 3 ] (B 6 H 7 ) 2 , (Ph 4 P)B 6 H 7 , [Ni(Phen) 3 ](B 6 H 7 ) 2 crystals (where Bipy = bipyridine, Phen = phenathroline, Ph = phenyl) are obtained via the exchange reaction with a subsequent recrystallization from aqua-acetonic and acetonic solutions. The structure is studied of a new borohydride anion B 6 H 7 - possessing a four-valence bond unique for polyhedral borohydride anions. A triangular face of boride skeleton coordinating a hydrogen atom is considerably larger than other faces, and the electron density on this hydrogen atom is evidently much higher than at the end hydride hydrogen atoms. The trend of B 6 H 7 - anion to form statistically disordered structurs testifies to a rather slight effect of the seventh hydrogen atom position on the structure pattern of the ionic crystal lattice

  4. Cytosolic nucleotides block and regulate the Arabidopsis vacuolar anion channel AtALMT9.

    Science.gov (United States)

    Zhang, Jingbo; Martinoia, Enrico; De Angeli, Alexis

    2014-09-12

    The aluminum-activated malate transporters (ALMTs) form a membrane protein family exhibiting different physiological roles in plants, varying from conferring tolerance to environmental Al(3+) to the regulation of stomatal movement. The regulation of the anion channels of the ALMT family is largely unknown. Identifying intracellular modulators of the activity of anion channels is fundamental to understanding their physiological functions. In this study we investigated the role of cytosolic nucleotides in regulating the activity of the vacuolar anion channel AtALMT9. We found that cytosolic nucleotides modulate the transport activity of AtALMT9. This modulation was based on a direct block of the pore of the channel at negative membrane potentials (open channel block) by the nucleotide and not by a phosphorylation mechanism. The block by nucleotides of AtALMT9-mediated currents was voltage dependent. The blocking efficiency of intracellular nucleotides increased with the number of phosphate groups and ATP was the most effective cellular blocker. Interestingly, the ATP block induced a marked modification of the current-voltage characteristic of AtALMT9. In addition, increased concentrations of vacuolar anions were able to shift the ATP block threshold to a more negative membrane potential. The block of AtALMT9-mediated anion currents by ATP at negative membrane potentials acts as a gate of the channel and vacuolar anion tune this gating mechanism. Our results suggest that anion transport across the vacuolar membrane in plant cells is controlled by cytosolic nucleotides and the energetic status of the cell. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Studies on ion scattering and sputtering processes relevant to ion beam sputter deposition of multicomponent thin films

    International Nuclear Information System (INIS)

    Auciello, O.; Ameen, M.S.; Kingon, A.I.

    1989-01-01

    Results from computer simulation and experiments on ion scattering and sputtering processes in ion beam sputter deposition of high Tc superconducting and ferroelectric thin films are presented. It is demonstrated that scattering of neutralized ions from the targets can result in undesirable erosion of, and inert gas incorporation in, the growing films, depending on the ion/target atom ass ratio and ion beam angle of incidence/target/substrate geometry. The studies indicate that sputtering Kr + or Xe + ions is preferable to the most commonly used Ar + ions, since the undesirable phenomena mentioned above are minimized for the first two ions. These results are used to determine optimum sputter deposition geometry and ion beam parameters for growing multicomponent oxide thin films by ion beam sputter-deposition. 10 refs., 5 figs

  6. The absorption of plutonium by anion resins

    Energy Technology Data Exchange (ETDEWEB)

    Durham, R. W.; Mills, R.

    1961-10-15

    Equilibrium experiments have shown Pu{sup +4} to be absorbed from nitric acid onto an anion resin as a complex anion Pu(NO{sub 3}){sub 6}{sup -2}. The amount of absorption is dependent on the plutonium and nitric acid concentrations in the equilibrium solution with a maximum at 7N to 8N HNO{sub 3}. A low cross-linked resin has a higher capacity and reaches equilibrium more rapidly than the normally supplied resin. Saturation capacity of one per cent cross-linked Nalcite SBR (Dowex 1), 50 -- 100 mesh, is 385 mg Pu/gram dry resin. (author)

  7. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization reactor, it is the best way to avoid any termination of living polymers during the number of steps for the synthesis of polymers with complex structure. In this chapter, we describe the different polymerization reactors and HVTs for the purification of monomers, solvents, and other reagents for anionic polymerization as well as few model reactions for the synthesis of polymers with simple to complex structure.

  8. Dibromine radical anion reactions with heme enzymes

    International Nuclear Information System (INIS)

    Gebicka, L.; Gebicki, J.L.

    1996-01-01

    Reactions of Br 2 radical anion with heme enzymes, catalase horseradish peroxidase, have been studied by pulse radiolysis. It has been found that Br 2 - does not react with the heme centre of investigated enzymes. Dibromine radical anion reacts with tryptophan residues of catalase without any influence on the activity of catalase. It is suggested that in pulse radiolysis studies, where horseradish peroxidase is at about tenfold excess toward Br 2 - , the enzyme is modified rather by Br 2 , than by Br 2 - . (author). 26 refs., 3 figs

  9. Fluence-dependent sputtering yield of micro-architectured materials

    Energy Technology Data Exchange (ETDEWEB)

    Matthes, Christopher S.R.; Ghoniem, Nasr M., E-mail: ghoniem@ucla.edu; Li, Gary Z.; Matlock, Taylor S.; Goebel, Dan M.; Dodson, Chris A.; Wirz, Richard E.

    2017-06-15

    Highlights: • Sputtering yield is shown to be transient and heavily dependent on surface architecture. • Fabricated nano- and Microstructures cause geometric re-trapping of sputtered material, which leads to a self-healing mechanism. • Initially, the sputtering yield of micro-architectured Mo is approximately 1/2 the value as that of a planar surface. • The study demonstrates that the sputtering yield is a dynamic property, dependent on the surface structure of a material. • A developed phenomenological model mathematically describes the transient behavior of the sputtering yield as a function of plasma fluence. - Abstract: We present an experimental examination of the relationship between the surface morphology of Mo and its instantaneous sputtering rate as function of low-energy plasma ion fluence. We quantify the dynamic evolution of nano/micro features of surfaces with built-in architecture, and the corresponding variation in the sputtering yield. Ballistic deposition of sputtered atoms as a result of geometric re-trapping is observed, and re-growth of surface layers is confirmed. This provides a self-healing mechanism of micro-architectured surfaces during plasma exposure. A variety of material characterization techniques are used to show that the sputtering yield is not a fundamental property, but that it is quantitatively related to the initial surface architecture and to its subsequent evolution. The sputtering yield of textured molybdenum samples exposed to 300 eV Ar plasma is roughly 1/2 of the corresponding value for flat samples, and increases with ion fluence. Mo samples exhibited a sputtering yield initially as low as 0.22 ± 5%, converging to 0.4 ± 5% at high fluence. The sputtering yield exhibits a transient behavior as function of the integrated ion fluence, reaching a steady-state value that is independent of initial surface conditions. A phenomenological model is proposed to explain the observed transient sputtering phenomenon, and to

  10. First observation of alkyne radical anions by electron spin resonance spectroscopy: Hexyne/n-hexane mixed crystals

    International Nuclear Information System (INIS)

    Matsuura, K.; Muto, H.

    1991-01-01

    The radical anions of alkynes have been first observed by electron spin resonance spectroscopy following alkene anions previously studied. Hexyne radical anions were formed in 1-, 2-, or 3-hexyne/n--hexane mixed crystals irradiated at 4.2 or 77 K. The characters of the anions were as follows; (a) the α-proton hyperfine coupling is very large (∼4.5 mT for the 1-hexyne anion), (b) the β-proton couplings are very small (∼1.0 mT for C--H β proton with the conformational angle of 0 degree), and (c) the radicals show a negative g shift (2.0014). From these observations, it was found that the anions have a nonlinear(bent) molecule structure in the anticonfiguration (trans C--C≡C--C) with the bend angle ∼60 degree, and that the unpaired electron orbital is approximately composed of the anticombination of the sp 2 hybrid orbitals of the C≡C carbon atoms. A discussion based on complete neglect of differential overlap (CNDO) molecular orbital (MO) calculations was given for the observed negative g shift, which was shown to be characteristic of the alkyne anions which have a high-lying unpaired electron orbital and an antibonding 2p--2p π carbon orbital just above it on the upper energy side

  11. A photoelectron imaging and quantum chemistry study of the deprotonated indole anion.

    Science.gov (United States)

    Parkes, Michael A; Crellin, Jonathan; Henley, Alice; Fielding, Helen H

    2018-05-29

    Indole is an important molecular motif in many biological molecules and exists in its deprotonated anionic form in the cyan fluorescent protein, an analogue of green fluorescent protein. However, the electronic structure of the deprotonated indole anion has been relatively unexplored. Here, we use a combination of anion photoelectron velocity-map imaging measurements and quantum chemistry calculations to probe the electronic structure of the deprotonated indole anion. We report vertical detachment energies (VDEs) of 2.45 ± 0.05 eV and 3.20 ± 0.05 eV, respectively. The value for D0 is in agreement with recent high-resolution measurements whereas the value for D1 is a new measurement. We find that the first electronically excited singlet state of the anion, S1(ππ*), lies above the VDE and has shape resonance character with respect to the D0 detachment continuum and Feshbach resonance character with respect to the D1 continuum.

  12. Selectivity, specificity, and sensitivity in the photoionization of sputtered species

    International Nuclear Information System (INIS)

    Gruen, D.M.; Calaway, W.F.; Pellin, M.J.; Young, C.E.; Spiegel, D.R.; Clayton, R.N.; Davis, A.M.; Blum, J.D.

    1990-01-01

    To deal with the problem of non- or near-resonant ionization, one needs to achieve the highest selectively for photoionization of the species of interest relative to isobarically overlapping species by choosing a specific photoionization scheme tailoring are that is could not have near-overlap with known atomic or molecular energy levels of isobaric species, and that it should lead to saturation of the resonance transitions at the lowest possible laser power levels so as to minimize two- and three-photon nonresonant photoionization processes. Experience has shown that, even when these two conditions are met as closely as possible, non- or near-resonant ionization can still occur, perhaps because of the existence of hitherto unobserved energy levels, photodissociation of sputtered molecules, or other effects. It is becoming clear that maximizing detection sensitivity for a particular species requires one to pay careful attention to the selection of an optimal photoionization scheme. It is the purpose of the present paper to illustrate this point with several examples and to help point the way to still further improvements in detection sensitivity by non- or near-resonant. ionization through detailed exploration of alternative photoionization schemes

  13. Nitrogen Atom Energy Distributions in a Hollow-cathode Planar Sputtering Magnetron

    International Nuclear Information System (INIS)

    Ruzic, D.N.; Goeckner, M.J.; Cohen, S.A.; Wang, Zhehui

    1999-01-01

    Energy distributions of N atoms in a hollow-cathode planar sputtering magnetron were obtained by use of optical emission spectroscopy. A characteristic line, N I 8216.3 , well-separated from molecular nitrogen emission bands, was identified. Jansson's nonlinear spectral deconvolution method, refined by minimization of χ w ampersand sup2; , was used to obtain the optimal deconvolved spectra. These showed nitrogen atom energies from 1 eV to beyond 500 eV. Based on comparisons with VFTRIM results, we propose that the energetic N atoms are generated from N 2 + ions after these ions are accelerated through the sheath and dissociatively reflect from the cathode

  14. Synthetic cation-selective nanotube: permeant cations chaperoned by anions.

    Science.gov (United States)

    Hilder, Tamsyn A; Gordon, Dan; Chung, Shin-Ho

    2011-01-28

    The ability to design ion-selective, synthetic nanotubes which mimic biological ion channels may have significant implications for the future treatment of bacteria, diseases, and as ultrasensitive biosensors. We present the design of a synthetic nanotube made from carbon atoms that selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics some of the salient properties of biological ion channels. Before practical nanodevices are successfully fabricated it is vital that proof-of-concept computational studies are performed. With this in mind we use molecular and stochastic dynamics simulations to characterize the dynamics of ion permeation across a single-walled (10, 10), 36 Å long, carbon nanotube terminated with carboxylic acid with an effective radius of 5.08 Å. Although cations encounter a high energy barrier of 7 kT, its height is drastically reduced by a chloride ion in the nanotube. The presence of a chloride ion near the pore entrance thus enables a cation to enter the pore and, once in the pore, it is chaperoned by the resident counterion across the narrow pore. The moment the chaperoned cation transits the pore, the counterion moves back to the entrance to ferry another ion. The synthetic nanotube has a high sodium conductance of 124 pS and shows linear current-voltage and current-concentration profiles. The cation-anion selectivity ratio ranges from 8 to 25, depending on the ionic concentrations in the reservoirs.

  15. Synthesis and characterization of Mg-Al-layered double hydroxides intercalated with cubane-1,4-dicarboxylate anions.

    Science.gov (United States)

    Rezvani, Zolfaghar; Arjomandi Rad, Farzad; Khodam, Fatemeh

    2015-01-21

    In the present work, Mg2Al-layered double hydroxide (LDH) intercalated with cubane-1,4-dicarboxylate anions was prepared from the reaction of solutions of Mg(ii) and Al(iii) nitrate salts with an alkaline solution of cubane-1,4-dicarboxylic acid by using the coprecipitation method. The successful preparation of a nanohybrid of cubane-1,4-dicarboxylate(cubane-dc) anions with LDH was confirmed by powder X-ray diffraction, FTIR spectroscopy and thermal gravimetric analysis (TGA). The increase in the basal spacing of LDHs from 8.67 Å to 13.40 Å shows that cubane-dc anions were successfully incorporated into the interlayer space. Thermogravimetric analyses confirm that the thermal stability of the intercalated cubane-dc anions is greater than that of the pure form before intercalation because of host-guest interactions involving hydrogen bonds. The interlayer structure, hydrogen bonding, and subsequent distension of LDH compounds containing cubane-dc anions were shown by molecular simulation. The RDF (radial distribution function), mean square displacement (MSD), and self-diffusion coefficient were calculated using the trajectory files on the basis of molecular dynamics (MD) simulations, and the results indicated that the cubane-dc anions were more stable when intercalated into the LDH layers. A good agreement was obtained between calculated and measured X-ray diffraction patterns and between experimental and calculated basal spacings.

  16. Selective resputtering of bismuth in sputtered Bi-Sr-Ca-Cu-O films

    Science.gov (United States)

    Grace, J. M.; McDonald, D. B.; Reiten, M. T.; Olson, J.; Kampwirth, R. T.; Gray, K. E.

    1991-10-01

    We present studies using a dc magnetron in an on-axis configuration to sputter Bi-Sr-Ca-Cu-O films from a composite target. These studies show that bismuth can be preferentially resputtered. The influence of ozone, molecular oxygen, and total pressure on the resputtering of bismuth is investigated and discussed. Ozone, in low concentrations, can dramatically affect the degree of resputtering. By comparing the effects of molecular oxygen and ozone, some insight is gained regarding the possible mechanisms of negative ion formation in the magnetron environment. Based on our results we suggest that molecular oxygen can bring about resputtering primarily by forming O+2, which collides with the target to produce energetic negative oxygen ions. In contrast, ozone may form negative ions by electron impact in the dark space above the target, giving rise to lower-energy negative ions, which can traverse the plasma unneutralized and can be stopped with an applied bias on the sample block. With no added oxidant, negative oxygen ions from the target oxygen may dominate the background resputtering. Similarity is found between our results and those for similar studies on Y-Ba-Cu-O by other workers. Bismuth in Bi-Sr-Ca-Cu-O behaves as barium in Y-Ba-Cu-O with regards to preferential resputtering; furthermore, the response of strontium, calcium, and copper to oxygen in sputtered Bi-Sr-Ca-Cu-O is similar to what is observed for copper in Y-Ba-Cu-O.

  17. Selective resputtering of bismuth in sputtered Bi-Sr-Ca-Cu-O films

    International Nuclear Information System (INIS)

    Grace, J.M.; McDonald, D.B.; Reiten, M.T.; Olson, J.; Kampwirth, R.T.; Gray, K.E.

    1991-01-01

    We present studies using a dc magnetron in an on-axis configuration to sputter Bi-Sr-Ca-Cu-O films from a composite target. These studies show that bismuth can be preferentially resputtered. The influence of ozone, molecular oxygen, and total pressure on the resputtering of bismuth is investigated and discussed. Ozone, in low concentrations, can dramatically affect the degree of resputtering. By comparing the effects of molecular oxygen and ozone, some insight is gained regarding the possible mechanisms of negative ion formation in the magnetron environment. Based on our results we suggest that molecular oxygen can bring about resputtering primarily by forming O + 2 , which collides with the target to produce energetic negative oxygen ions. In contrast, ozone may form negative ions by electron impact in the dark space above the target, giving rise to lower-energy negative ions, which can traverse the plasma unneutralized and can be stopped with an applied bias on the sample block. With no added oxidant, negative oxygen ions from the target oxygen may dominate the background resputtering. Similarity is found between our results and those for similar studies on Y-Ba-Cu-O by other workers. Bismuth in Bi-Sr-Ca-Cu-O behaves as barium in Y-Ba-Cu-O with regards to preferential resputtering; furthermore, the response of strontium, calcium, and copper to oxygen in sputtered Bi-Sr-Ca-Cu-O is similar to what is observed for copper in Y-Ba-Cu-O

  18. The assessment of pellicular anion-exchange resins for the determination of anions by ion chromatography

    International Nuclear Information System (INIS)

    Pohlandt, C.

    1981-01-01

    Because pellicular anion-exchange resins suitable for the determination, by ion chromatography, of anions with alkaline eluents were unavailable in South Africa at the inception of this work, an attempt was made to prepare such resins. In this study it is shown that the pellicular resins produced are more efficient than the surface-aminated resins used previously. The simultaneous separation and determination of five common anions is demonstrated. The method was applied to the analysis of uranium leach liquors, effluent samples, and a solid sample of ferric oxide (goethite)

  19. Study on re-sputtering during CN{sub x} film deposition through spectroscopic diagnostics of plasma

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Peipei; Yang, Xu; Li, Hui; Cai, Hua [Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China); Sun, Jian; Xu, Ning [Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China); Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Fudan University, Shanghai 200433 (China); Wu, Jiada, E-mail: jdwu@fudan.edu.cn [Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China); Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Fudan University, Shanghai 200433 (China); Engineering Research Center of Advanced Lighting Technology, Ministry of Education, Fudan University, Shanghai 200433 (China)

    2015-10-15

    A nitrogen-carbon plasma was generated during the deposition of carbon nitride (CN{sub x}) thin films by pulsed laser ablation of a graphite target in a discharge nitrogen plasma, and the optical emission of the generated nitrogen-carbon plasma was measured for the diagnostics of the plasma and the characterization of the process of CN{sub x} film deposition. The nitrogen-carbon plasma was recognized to contain various species including nitrogen molecules and molecular ions excited in the ambient N{sub 2} gas, carbon atoms and atomic ions ablated from the graphite target and CN radicals. The temporal evolution and spatial distribution of the CN emission and their dependence on the substrate bias voltage show two groups of CN radicals flying in opposite directions. One represents the CN radicals formed as the products of the reactions occurring in the nitrogen-carbon plasma, revealing the reactive deposition of CN{sub x} film due to the reactive expansion of the ablation carbon plasma in the discharge nitrogen plasma and the effective formation of gaseous CN radicals as precursors for CN{sub x} film growth. The other one represents the CN radicals re-sputtered from the growing CN{sub x} film by energetic plasma species, evidencing the re-sputtering of the growing film accompanying film growth. And, the re-sputtering presents ion-induced sputtering features.

  20. Structural and magnetic properties of NiZn-ferrite thin films prepared by radio frequency magnetron sputtering

    International Nuclear Information System (INIS)

    Liu Yingli; Li Yuanxun; Zhang Huaiwu; Chen Daming; Mu Chunhong

    2011-01-01

    Polycrystalline NiZn-ferrite thin films were deposited on Si(100) substrate by rf magnetron sputtering, using targets with a nominal composition of Ni 0.5 Zn 0.5 Fe 2 O 4 . The effects of substrate condition, sputtering pressure, and postannealing on the structure and magnetic properties of thin films have been investigated. Our results show that the preferred orientation of the NiZn spinel film changed from (311) to (400) with increasing the Ar pressure from 0.8 to 1.6 Pa, meanwhile, the grain size also increased. Atomic force microscopy analysis indicates that perfect surface morphology of the film can be obtained at a relatively lower sputtering pressure of 1.0 Pa. The relative percentage of residual oxygen increases significantly on a condition of lower sputtering pressure, and plays an important role in film structure due to the strong molecular adsorption tendency of oxygen on the film surface during the deposition process. A thin film with a typical thickness of 1 μm, a saturation magnetization of 150 emu/cm 3 , and a coercivity of 8.8 kA/m has been obtained after annealing at 800 deg. C, which has the potential application in magnetic integrated circuits.

  1. Effect of Carbon Concentration on the Sputtering of Carbon-Rich SiC Bombarded by Helium Ions

    Directory of Open Access Journals (Sweden)

    Xinghao Liang

    2018-02-01

    Full Text Available Silicon carbide (SiC is considered as an important material for nuclear engineering due to its excellent properties. Changing the carbon content in SiC can regulate and control its elastic and thermodynamic properties, but a simulation study of the effect of carbon content on the sputtering (caused by the helium ions of SiC is still lacking. In this work, we used the Monte-Carlo and molecular dynamics simulation methods to study the effects of carbon concentration, incidence energy, incident angle, and target temperature on the sputtering yield of SiC. The results show that the incident ions’ energy and angle have a significant effect on sputtering yield of SiC when the carbon concentration in SiC is around 62 at %, while the target temperature has a little effect on the sputtering yield of SiC. Our work might provide theoretical support for the experimental research and engineering application of carbon fiber-reinforced SiC that be used as the plasma-facing material in tokamak fusion reactors.

  2. High power pulsed magnetron sputtering of transparent conducting oxides

    International Nuclear Information System (INIS)

    Sittinger, V.; Ruske, F.; Werner, W.; Jacobs, C.; Szyszka, B.; Christie, D.J.

    2008-01-01

    High power pulsed magnetron sputtering (HPPMS) has been used in order to study the deposition of transparent conducting oxides. We summarize the studies carried out on different materials (indium tin oxide-ITO and aluminium-doped zinc oxide-AZO) using rather different technological approaches, namely sputtering of ceramic targets and reactive sputtering. For the deposition of AZO reactive HPPMS for metallic targets has been used. A feedback control loop has been implemented in order to stabilize the discharge at any given setpoint on the hysteresis curve. The hysteresis was also found to have a rather untypical form. Reactive HPPMS was found to be a promising tool for obtaining high quality films of low total thickness. In the case of ITO deposition a ceramic target has been used. The process has been characterized in terms of its plasma emission and increasing indium ionization was found for higher peak power densities. The properties of the deposited films were compared to DC sputtered films. While for DC sputtering the choice of oxygen addition and shieldings is crucial for determining surface morphology and resistivity, in HPPMS sputtering peak power density has been found to be a good parameter for influencing the crystal structure. The morphologies obtained differ strongly from those seen in DC sputtering. At high power densities films with low surface roughness and excellent resistivity could be deposited without the use of shieldings

  3. Reactive dual magnetron sputtering for large area application

    International Nuclear Information System (INIS)

    Struempfel, J.

    2002-01-01

    Production lines for large area coating demand high productivity of reactive magnetron sputtering processes. Increased dynamic deposition rates for oxides and nitrides were already obtained by using of highly powered magnetrons in combination with advanced sputter techniques. However, besides high deposition rates the uniformity of such coatings has to be carefully considered. First the basics of reactive sputtering processes and dual magnetron sputtering are summarized. Different methods for process stabilization and control are commonly used for reactive sputtering. The Plasma Emission Monitor (PE M) offers the prerequisite for fast acting process control derived from the in-situ intensity measurements of a spectral line of the sputtered target material. Combined by multiple Plasma Emission Monitor control loops segmented gas manifolds are able to provide excellent thin film uniformity at high deposition rates. The Dual Magnetron allows a broad range of processing by different power supply modes. Medium frequency, DC and pulsed DC power supplies can be used for high quality layers. Whereas the large area coating of highly isolating layers like TiO 2 or SiO 2 is dominated by MF sputtering best results for coating with transparent conductive oxides are obtained by dual DC powering of the dual magnetron arrangement. (Author)

  4. Transport theory of sputtering I: Depth of origin of sputtered atoms

    International Nuclear Information System (INIS)

    Zhang, Zhu Lin

    1999-01-01

    Sputter theory employing a sum of two power cross sections has been implemented. Compared with the well known Lindhard power cross section (V∝r -1/m ), a sum of two such cross sections can give a much better approximation to the Born-Mayer scattering in the low energy region (m ∼ 0.1). By using both one and two power cross sections, we have solved the linear transport equations describing the sputtering problem asymptotically. As usual, electronic stopping is ignored in the analysis. It has further been proved that Falcone's theory of the atom ejection process contradicts transport theory. The Andersen-Sigmund relation for partial sputtering yield ratios between two elements in an arbitrary multicomponent target has been derived by both methods. The energy deposited in the target surface layers has been computed for a few typical ion-target combinations. The numerical curves show that both theories generate almost the same results (error m≥0. The former even may be only about one half of the latter as long as m=0

  5. High rate reactive sputtering in an opposed cathode closed-field unbalanced magnetron sputtering system

    Science.gov (United States)

    Sproul, William D.; Rudnik, Paul J.; Graham, Michael E.; Rohde, Suzanne L.

    1990-01-01

    Attention is given to an opposed cathode sputtering system constructed with the ability to coat parts with a size up to 15 cm in diameter and 30 cm in length. Initial trials with this system revealed very low substrate bias currents. When the AlNiCo magnets in the two opposed cathodes were arranged in a mirrored configuration, the plasma density at the substrate was low, and the substrate bias current density was less than 1 mA/sq cm. If the magnets were arranged in a closed-field configuration where the field lines from one set of magnets were coupled with the other set, the substrate bias current density was as high as 5.7 mA/sq cm when NdFeB magnets were used. In the closed-field configuration, the substrate bias current density was related to the magnetic field strength between the two cathodes and to the sputtering pressure. Hard well-adhered TiN coatings were reactively sputtered in the opposed cathode system in the closed-field configuration, but the mirrored configuration produced films with poor adhesion because of etching problems and low plasma density at the substrate.

  6. Carbon Incorporation and Anion Dynamics as Synergistic Drivers for Ultrafast Diffusion in Superionic LiCB11H12 and NaCB11H12

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrievska, Mirjana [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Shea, Patrick [Lawrence Livermore National Laboratory; Kweon, Kyoung E. [Lawrence Livermore National Laboratory; Bercx, Marnik [University of Antwerp; Varley, Joel B. [Lawrence Livermore National Laboratory; Tang, Wan Si [National Institute of Standards and Technology; University of Maryland; Skripov, Alexander V. [Ural Division of the Russian Academy of Sciences; Stavila, Vitalie [Sandia National Laboratories; Udovic, Terrence J. [National Institute of Standards and Technology; Wood, Brandon C. [Lawrence Livermore National Laboratory

    2018-02-02

    The disordered phases of LiCB11H12 and NaCB11H12 possess superb superionic conductivities that make them suitable as solid electrolytes. In these materials, cation diffusion correlates with high orientational mobilities of the CB11H12- anions; however, the precise relationship has yet to be demonstrated. In this work, ab initio molecular dynamics and quasielastic neutron scattering are combined to probe anion reorientations and their mechanistic connection to cation mobility over a range of timescales and temperatures. It is found that anions do not rotate freely, but rather transition rapidly between orientations defined by the cation sublattice symmetry. The symmetry-breaking carbon atom in CB11H12- also plays a critical role by perturbing the energy landscape along the instantaneous orientation of the anion dipole, which couples fluctuations in the cation probability density directly to the anion motion. Anion reorientation rates exceed 3 x 1010 s-1, suggesting the underlying energy landscape fluctuates dynamically on diffusion-relevant timescales. Furthermore, carbon is found to modify the orientational preferences of the anions and aid rotational mobility, creating additional symmetry incompatibilities that inhibit ordering. The results suggest that synergy between the anion reorientational dynamics and the carbon-modified cation-anion interaction accounts for the higher ionic conductivity in CB11H12- salts compared with B12H122-.

  7. Interstellar dehydrogenated PAH anions: vibrational spectra

    Science.gov (United States)

    Buragohain, Mridusmita; Pathak, Amit; Sarre, Peter; Gour, Nand Kishor

    2018-03-01

    Interstellar polycyclic aromatic hydrocarbon (PAH) molecules exist in diverse forms depending on the local physical environment. Formation of ionized PAHs (anions and cations) is favourable in the extreme conditions of the interstellar medium (ISM). Besides in their pure form, PAHs are also likely to exist in substituted forms; for example, PAHs with functional groups, dehydrogenated PAHs etc. A dehydrogenated PAH molecule might subsequently form fullerenes in the ISM as a result of ongoing chemical processes. This work presents a density functional theory (DFT) calculation on dehydrogenated PAH anions to explore the infrared emission spectra of these molecules and discuss any possible contribution towards observed IR features in the ISM. The results suggest that dehydrogenated PAH anions might be significantly contributing to the 3.3 μm region. Spectroscopic features unique to dehydrogenated PAH anions are highlighted that may be used for their possible identification in the ISM. A comparison has also been made to see the size effect on spectra of these PAHs.

  8. Anion-conducting polymer, composition, and membrane

    Science.gov (United States)

    Pivovar, Bryan S [Los Alamos, NM; Thorn, David L [Los Alamos, NM

    2009-09-01

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  9. Synthesis of azaphenanthridines via anionic ring closure

    DEFF Research Database (Denmark)

    Hansen, Henriette Møller; Lysén, M.; Begtrup, M.

    2005-01-01

    A new and convergent synthesis of azaphenanthridines via an anionic ring closure is reported. Ortho-lithiation/in situ borylation of cyanopyridines produces the corresponding cyanopyridylboronic esters, which undergo a Suzuki-Miyaura cross-coupling to give the key intermediates. Addition of lithium...

  10. Sputtering of neutral and ionic indium clusters

    International Nuclear Information System (INIS)

    Ma, Z.; Coon, S.R.; Calaway, W.F.; Pellin, M.J.; Gruen, D.M.; Von Nagy-Felsobuki, E.I.

    1993-01-01

    Secondary neutral and secondary ion cluster yields were measured during the sputtering of a polycrystalline indium surface by normally incident ∼4 keV Ar + ions. In the secondary neutral mass spectra, indium clusters as large as In 32 were observed. In the secondary ion mass spectra, indium clusters up to In 18 + were recorded. Cluster yields obtained from both the neutral and ion channel exhibited a power law dependence on the number of constituent atoms, n, in the cluster, with the exponents measured to be -5.6 and -4. 1, respectively. An abundance drop was observed at n=8, 15, and 16 in both the neutral and ion yield distributions suggesting that the stability of the ion (either secondary ion or photoion) plays a significant role in the observed distributions. In addition, our experiments suggest that unimolecular decomposition of the neutral cluster may also plays an important role in the measured yield distributions

  11. Laser micromachining of sputtered DLC films

    International Nuclear Information System (INIS)

    Fu, Y.Q.; Luo, J.K.; Flewitt, A.J.; Ong, S.E.; Zhang, S.; Milne, W.I.

    2006-01-01

    DLC films with different thicknesses (from 100 nm to 1.9 μm) were deposited using sputtering of graphite target in pure argon atmosphere without substrate heating. Film microstructures (sp 2 /sp 3 ratio) and mechanical properties (modulus, hardness, stress) were characterized as a function of film thickness. A thin layer of aluminum about 60 nm was deposited on the DLC film surface. Laser micromachining of Al/DLC layer was performed to form microcantilever structures, which were released using a reactive ion etching system with SF 6 plasma. Due to the intrinsic stress in DLC films and bimorph Al/DLC structure, the microcantilevers bent up with different curvatures. For DLC film of 100 nm thick, the cantilever even formed microtubes. The relationship between the bimorph beam bending and DLC film properties (such as stress, modulus, etc.) were discussed in details

  12. Magnetostrictive thin films prepared by RF sputtering

    International Nuclear Information System (INIS)

    Carabias, I.; Martinez, A.; Garcia, M.A.; Pina, E.; Gonzalez, J.M.; Hernando, A.; Crespo, P.

    2005-01-01

    Fe 80 B 20 thin films have been prepared by ion beam sputtering magnetron on room temperature. The films were fabricated on different substrates to compare the different magnetic and structural properties. In particular the growth of films on flexible substrates (PDMS, Kapton) has been studied to allow a simple integration of the system in miniaturized magnetostrictive devices. X-ray diffraction patterns indicate that films are mainly amorphous although the presence of some Fe nanoparticles cannot be ruled out. The coercive field of thin films ranges between 15 and 35 Oe, depending on substrate. Magnetostriction measurements indicate the strong dependence of the saturation magnetostriction with the substrate. Samples on flexible substrates exhibit a better performance than samples deposited onto glass substrates

  13. Fuzzy tungsten in a magnetron sputtering device

    Energy Technology Data Exchange (ETDEWEB)

    Petty, T.J., E-mail: tjpetty@liv.ac.uk [Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ (United Kingdom); Khan, A. [Pariser Building-G11, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester, M13 9PL (United Kingdom); Heil, T. [NiCaL, Block C Waterhouse Building, 1-3 Brownlow Street, Liverpool, L69 3GL (United Kingdom); Bradley, J.W., E-mail: j.w.bradley@liverpool.ac.uk [Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ (United Kingdom)

    2016-11-15

    Helium ion induced tungsten nanostructure (tungsten fuzz) has been studied in a magnetron sputtering device. Three parameters were varied, the fluence from 3.4 × 10{sup 23}–3.0 × 10{sup 24} m{sup −2}, the He ion energy from 25 to 70 eV, and the surface temperature from 900 to 1200 K. For each sample, SEM images were captured, and measurements of the fuzz layer thickness, surface roughness, reflectivity, and average structure widths are provided. A cross-over point from pre-fuzz to fully formed fuzz is found at 2.4 ± 0.4 × 10{sup 24} m{sup −2}, and a temperature of 1080 ± 60 K. No significant change was observed in the energy sweep. The fuzz is compared to low fluence fuzz created in the PISCES-A linear plasma device. Magnetron fuzz is less uniform than fuzz created by PISCES-A and with generally larger structure widths. The thicknesses of the magnetron samples follow the original Φ{sup 1/2} relation as opposed to the incubation fluence fit. - Highlights: • Fuzz has been created in a magnetron sputtering device. • Three parameters for fuzz formation have been swept. • A cross-over from pre-fuzz to fully formed fuzz is seen. • Evidence for annealing out at lower temperatures than has been seen before. • Evidence to suggest that fuzz grown in discrete exposures is not consistent with fuzz grown in one long exposure.

  14. Fuzzy tungsten in a magnetron sputtering device

    International Nuclear Information System (INIS)

    Petty, T.J.; Khan, A.; Heil, T.; Bradley, J.W.

    2016-01-01

    Helium ion induced tungsten nanostructure (tungsten fuzz) has been studied in a magnetron sputtering device. Three parameters were varied, the fluence from 3.4 × 10 23 –3.0 × 10 24  m −2 , the He ion energy from 25 to 70 eV, and the surface temperature from 900 to 1200 K. For each sample, SEM images were captured, and measurements of the fuzz layer thickness, surface roughness, reflectivity, and average structure widths are provided. A cross-over point from pre-fuzz to fully formed fuzz is found at 2.4 ± 0.4 × 10 24  m −2 , and a temperature of 1080 ± 60 K. No significant change was observed in the energy sweep. The fuzz is compared to low fluence fuzz created in the PISCES-A linear plasma device. Magnetron fuzz is less uniform than fuzz created by PISCES-A and with generally larger structure widths. The thicknesses of the magnetron samples follow the original Φ 1/2 relation as opposed to the incubation fluence fit. - Highlights: • Fuzz has been created in a magnetron sputtering device. • Three parameters for fuzz formation have been swept. • A cross-over from pre-fuzz to fully formed fuzz is seen. • Evidence for annealing out at lower temperatures than has been seen before. • Evidence to suggest that fuzz grown in discrete exposures is not consistent with fuzz grown in one long exposure.

  15. Anionic Palladium(0) and Palladium(II) Ate Complexes.

    Science.gov (United States)

    Kolter, Marlene; Böck, Katharina; Karaghiosoff, Konstantin; Koszinowski, Konrad

    2017-10-16

    Palladium ate complexes are frequently invoked as important intermediates in Heck and cross-coupling reactions, but so far have largely eluded characterization at the molecular level. Here, we use electrospray-ionization mass spectrometry, electrical conductivity measurements, and NMR spectroscopy to show that the electron-poor catalyst [L 3 Pd] (L=tris[3,5-bis(trifluoromethyl)phenyl]phosphine) readily reacts with Br - ions to afford the anionic, zero-valent ate complex [L 3 PdBr] - . In contrast, more-electron-rich Pd catalysts display lower tendencies toward the formation of ate complexes. Combining [L 3 Pd] with LiI and an aryl iodide substrate (ArI) results in the observation of the Pd II ate complex [L 2 Pd(Ar)I 2 ] - . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Radiation-induced decomposition of anion exchange resins

    International Nuclear Information System (INIS)

    Baidak, Aliaksandr; LaVerne, Jay A.

    2010-01-01

    Radiation-induced degradation of the strongly basic anion exchange resin Amberlite TM IRA400 in NO 3 - , Cl - and OH - forms has been studied. The research focused on the formation of molecular hydrogen in the gamma-radiolysis of water slurries of these quaternary ammonium resins with varying water content. Extended studies with various electron scavengers (NO 3 - , N 2 O and O 2 ) prove an important role of e solv - in the formation of H 2 from these resins. An excess production of H 2 in these systems at about 85% water weight fraction was found to be due to trimethylamine, dimethylamine and other compounds that leach from the resin to the aqueous phase. Irradiations with 5 MeV 4 He ions were performed to simulate the effects of α-particles.

  17. Modelling the transport of carbonic acid anions through anion-exchange membranes

    International Nuclear Information System (INIS)

    Nikonenko, V.; Lebedev, K.; Manzanares, J.A.; Pourcelly, G.

    2003-01-01

    Electrodiffusion of carbonate and bicarbonate anions through anion-exchange membranes (AEM) is described on the basis of the Nernst-Planck equations taking into account coupled hydrolysis reactions in the external diffusion boundary layers (DBLs) and internal pore solution. The model supposes local electroneutrality as well as chemical and thermodynamic equilibrium. The transport is considered in three layers being an anion exchange membrane and two adjoining diffusion layers. A mechanism of competitive transport of HCO 3 - and CO 3 2- anions through the membrane which takes into account Donnan exclusion of H + ions is proposed. It is predicted that the pH of the depleting solution decreases and that of the concentrating solution increases during electrodialysis (ED). Eventual deviations from local electroneutrality and local chemical equilibrium are discussed

  18. Metal-Anion Pairing at Oxide/Water Interfaces: Theoretical and Experimental Investigations from the Nanoscale to the Macroscale

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Heather [The Ohio State Univ., Columbus, OH (United States)

    2016-11-14

    We combine the use of several techniques including bulk adsorption experiments, X-ray absorption, infrared, total internal reflection Raman, and vibrational sum frequencygeneration (XAS, IR, TIR-Raman, VSFG) spectroscopies, and molecular modeling to investigate ion adsorption at mineral surfaces. XAS and TIR-Raman provides data on how the metal binds to the surface (e.g., monodentate, bidentate), IR provides data on bulk anion adsorption at mineral surfaces from aqueous solutions, and VSFG provides surface specific data on anion adsorption at the mineral surface as well as impact of adsorbed metal-anion pairs on water structure at the mineral surface. Molecular modeling is used to guide spectroscopic data interpretation by providing information on water structure around ions in solution and the structure of metal-anion complexes in aqueous solutions. In addition, molecular modeling is used to provide insight into water structure at mineral surfaces, the surface sites involved in ion adsorption, and the distribution of ion pairs between aqueous solution and the mineral surface. Our studies have focused on systems involving alkaline earth metal (Mg2+, Ca2+, Sr2+, Ba2+) and heavy metal (Co2+, Cd2+) cations. The anions we have selected for studyinclude Cl-, NO3-, ClO4-, SO42-, SeO32-, and SeO42-. Ion adsorption and the potential formation ofternary complexes on silica (quartz, amorphous silica), alumina (corundum and gibbsite), and ferric iron oxides (goethite and hematite) are under investigation.

  19. Regulation of organic anion transport in the liver

    NARCIS (Netherlands)

    Roelofsen, H; Jansen, PLM

    1997-01-01

    In several liver diseases the biliary transport is disturbed, resulting in, for example, jaundice and cholestasis. Many of these symptoms can be attributed to altered regulation of hepatic transporters. Organic anion transport, mediated by the canalicular multispecific organic anion transporter

  20. Changes in plasma osmolality and anion gap: potential predictors of ...

    African Journals Online (AJOL)

    Changes in plasma osmolality and anion gap: potential predictors of ... PROMOTING ACCESS TO AFRICAN RESEARCH ... Objective: To determine the relationship of mortality to plasma osmolality and anion gap inpatients on haemodialysis.

  1. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    International Nuclear Information System (INIS)

    Sessler, Jonathan L.

    2007-01-01

    The major thrust of this project, led by the University of Kansas (Prof. Kristin Bowman-James), entails an exploration of the basic determinants of anion recognition and their application to the design, synthesis, and testing of novel sulfate extractants. A key scientific inspiration for the work comes from the need, codified in simple-to-appreciate terms by the Oak Ridge National Laboratory component of the team (viz. Dr. Bruce Moyer), for chemical entities that can help in the extractive removal of species that have low solubilities in borosilicate glass. Among such species, sulfate anion, has been identified as particularly insidious. Its presence interferes with the vitrification process, thus rendering the remediation of tank waste from, e.g., the Hanford site far more difficult and expensive. The availability of effective extractants, that would allow for the separation of separating sulfate from the major competing anions in the waste, especially nitrate, could allow for pre-vitrification removal of sulfate via liquid-liquid extraction. The efforts at The University of Texas, the subject of this report, have thus concentrated on the development of new sulfate receptors. These systems are designed to increase our basic understanding of anion recognition events and set the stage for the development of viable sulfate anion extractants. In conjunction with the Oak Ridge National Laboratory (ORNL) members of the research team, several of these new receptors were studied as putative extractants, with two of the systems being shown to act as promising synergists for anion exchange.

  2. Self-sputtering runaway in high power impulse magnetron sputtering: The role of secondary electrons and multiply charged metal ions

    International Nuclear Information System (INIS)

    Anders, Andre

    2008-01-01

    Self-sputtering runaway in high power impulse magnetron sputtering is closely related to the appearance of multiply charged ions. This conclusion is based on the properties of potential emission of secondary electrons and energy balance considerations. The effect is especially strong for materials whose sputtering yield is marginally greater than unity. The absolute deposition rate increases ∼Q 1/2 , whereas the rate normalized to the average power decreases ∼Q -1/2 , with Q being the mean ion charge state number

  3. On the microstructure and interfacial properties of sputtered nickel ...

    Indian Academy of Sciences (India)

    Administrator

    On the microstructure and interfacial properties of sputtered nickel ... (FE-SEM) and atomic force microscope (AFM) revealed columnar morphology with voided boundaries for ..... compound phase formation by performing the deposition.

  4. Sputter-Resistant Materials for Electric Propulsion, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase 2 project shall develop sputter-resistant materials for use in electric propulsion test facilities and for plume shields on spacecraft using electric...

  5. Preliminary results on adhesion improvement using Ion Beam Sputtering Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yonggi; Kim, Bomsok; Lee, Jaesang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    Sputtering is an established technique for depositing films with smooth surfaces and interfaces and good thick control. Ejection of articles from a condensed matter due to impingement of high energy particles, termed as sputtering was observed as early as in 1852, however, it is only recently that the complex process of sputtering system. Coating adhesion and environmental stability of the ion beam sputtering deposition coatings performed very well. High-energy high-current ion beam thin film synthesis of adhesion problems can be solved by using. Enhancement of adhesion in thin film synthesis, using high energy and high current ion beam, of mobile phones, car parts and other possible applications in the related industry Alternative technology of wet chrome plating, considering environment and unit cost, for car parts and esthetic improvement on surface of domestic appliances.

  6. Preliminary results on adhesion improvement using Ion Beam Sputtering Deposition

    International Nuclear Information System (INIS)

    Kim, Yonggi; Kim, Bomsok; Lee, Jaesang

    2013-01-01

    Sputtering is an established technique for depositing films with smooth surfaces and interfaces and good thick control. Ejection of articles from a condensed matter due to impingement of high energy particles, termed as sputtering was observed as early as in 1852, however, it is only recently that the complex process of sputtering system. Coating adhesion and environmental stability of the ion beam sputtering deposition coatings performed very well. High-energy high-current ion beam thin film synthesis of adhesion problems can be solved by using. Enhancement of adhesion in thin film synthesis, using high energy and high current ion beam, of mobile phones, car parts and other possible applications in the related industry Alternative technology of wet chrome plating, considering environment and unit cost, for car parts and esthetic improvement on surface of domestic appliances

  7. Antibacterial properties of palladium nanostructures sputtered on polyethylene naphthalate

    Czech Academy of Sciences Publication Activity Database

    Polívková, M.; Válová, M.; Siegel, J.; Rimpelová, S.; Hubáček, Tomáš; Lyutakov, O.; Švorčík, V.

    2015-01-01

    Roč. 5, č. 90 (2015), s. 73767-73774 ISSN 2046-2069 Institutional support: RVO:60077344 Keywords : polymer * palladium sputtering * annealing * nanostructure * antibacterial effect Subject RIV: JJ - Other Materials Impact factor: 3.289, year: 2015

  8. Nanopatterning of swinging substrates by ion-beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sun Mi; Kim, J.-S., E-mail: jskim@sm.ac.kr [Department of Physics, Sookmyung Women' s University, Seoul 140-742 (Korea, Republic of)

    2016-05-28

    Graphite substrates are azimuthally swung during ion-beam sputtering (IBS) at a polar angle θ = 78° from the surface normal. The swinging of the substrate not only causes quasi-two-dimensional mass transport but also makes various sputter effects from the different incident angles to work together. Through variation of the swing angle, both the transport and sputtering effects synergistically produce a series of salient patterns, such as asymmetric wall-like structures, which can grow to several tens of nanometers and exhibit a re-entrant orientational change with the increased swing angle. Thus, the present work demonstrates that dynamic variables such as the swing angle, which have been little utilized, offer an additional parameter space that can be exploited to diversify the sputtered patterns, thereby expanding the applicability of an IBS as well as the comprehension of the IBS nano patterning mechanism.

  9. Development of ion beam sputtering techniques for actinide target preparation

    International Nuclear Information System (INIS)

    Aaron, W.S.; Zevenbergen, L.A.; Adair, H.L.

    1985-01-01

    Ion beam sputtering is a routine method for the preparation of thin films used as targets because it allows the use of minimum quantity of starting material, and losses are much lower than most other vacuum deposition techniques. Work is underway in the Isotope Research Materials Laboratory (IRML) at ORNL to develop the techniques that will make the preparation of actinide targets up to 100 μg/cm 2 by ion beam sputtering a routinely available service from IRML. The preparation of the actinide material in a form suitable for sputtering is a key to this technique, as is designing a sputtering system that allows the flexibility required for custom-ordered target production. At present, development work is being conducted on low-activity in a bench-top system. The system will then be installed in a hood or glove box approved for radioactive materials handling where processing of radium, actinium, and plutonium isotopes among others will be performed. (orig.)

  10. Sputtering of Au induced by single Xe ion impacts

    International Nuclear Information System (INIS)

    Birtcher, R. C.; Donnelly, S. E.

    1999-01-01

    Sputtering of Au thin films has been determined for Xe ions with energies between 50 and 600 keV. In-situ transmission electron microscopy was used to observe sputtered Au during deposition on a carbon foil near the specimen. Total reflection and transmission sputtering yields for a 62 nm thick Au thin film were determined by ex-situ measurement of the total amount of Au on the carbon foils. In situ observations show that individual Xe ions eject Au nanoparticles as large as 7 nm in diameter with an average diameter of approximately 3 nm. Particle emission correlates with crater formation due to single ion impacts. Nanoparticle emission contributes significantly to the total sputtering yield for Xe ions in this energy range in either reflection or transmission geometry

  11. CO2 gas sensitivity of sputtered zinc oxide thin films

    Indian Academy of Sciences (India)

    TECS

    Gas sensitivity; ZnO; sputtering; XRD patterns; structure; thin films. 1. Introduction. Because zinc ... voltage and absorption properties of those fabricated films have been ... tations are useful in many physical applications. The in- plane (Hegde ...

  12. Sputtering mechanisms of polycrystalline platinum by low energy ions

    International Nuclear Information System (INIS)

    Chernysh, V.S.; Eckstein, W.; Haidarov, A.A.; Kulikauskas, V.S.; Mashkova, E.S.; Molchanov, V.A.

    1999-01-01

    The results of an experimental study and a computer simulation with the TRIM.SP code of the angular distributions of atoms sputtered from polycrystalline platinum under 1.5-9 keV He + bombardment at the normal ion incidence are presented. It has been found that angular distributions of sputtered atoms are overcosine and that their shape is practically independent of the bombarding ion species and ion energy. Good agreement between experimental results and computer simulation data was found. Computer simulations of the partial angular distributions of Pt atoms ejected due to various sputtering mechanisms for He and Ar bombardments were performed. The role of different mechanisms in the formation of angular distributions of sputtered atoms has been analyzed

  13. Sputtering of two-phase AgxCuγ alloys

    International Nuclear Information System (INIS)

    Bibic, N.; Milosavljevic, M.; Perusko, D.; Wilson, I.H.

    1992-01-01

    Elemental sputtering yields from two phase AgCu alloys were measured for 20, 40 and 50 at % Ag. Argon ion bombardment energies were in the range 35-55 keV and the ion dose was 1 x 10 19 ions cm -2 . The sputtering yield for silver was found to be considerably below what was expected by simple selective sputtering of a two component alloy. Analysis by electron probe X-ray microanalysis and scanning electron microscopy of the eroded surface indicated that surface diffusion of copper from copper rich grains and geometrical constraints in the dense cone forest on Cu/Ag eutectic regions combine to reduce the sputtering yield for silver. (author)

  14. Nanopatterning of swinging substrates by ion-beam sputtering

    International Nuclear Information System (INIS)

    Yoon, Sun Mi; Kim, J.-S.

    2016-01-01

    Graphite substrates are azimuthally swung during ion-beam sputtering (IBS) at a polar angle θ = 78° from the surface normal. The swinging of the substrate not only causes quasi-two-dimensional mass transport but also makes various sputter effects from the different incident angles to work together. Through variation of the swing angle, both the transport and sputtering effects synergistically produce a series of salient patterns, such as asymmetric wall-like structures, which can grow to several tens of nanometers and exhibit a re-entrant orientational change with the increased swing angle. Thus, the present work demonstrates that dynamic variables such as the swing angle, which have been little utilized, offer an additional parameter space that can be exploited to diversify the sputtered patterns, thereby expanding the applicability of an IBS as well as the comprehension of the IBS nano patterning mechanism.

  15. Magnetospheric ion sputtering and water ice grain size at Europa

    Science.gov (United States)

    Cassidy, T. A.; Paranicas, C. P.; Shirley, J. H.; Dalton, J. B., III; Teolis, B. D.; Johnson, R. E.; Kamp, L.; Hendrix, A. R.

    2013-03-01

    We present the first calculation of Europa's sputtering (ion erosion) rate as a function of position on Europa's surface. We find a global sputtering rate of 2×1027 H2O s-1, some of which leaves the surface in the form of O2 and H2. The calculated O2 production rate is 1×1026 O2 s-1, H2 production is twice that value. The total sputtering rate (including all species) peaks at the trailing hemisphere apex and decreases to about 1/3rd of the peak value at the leading hemisphere apex. O2 and H2 sputtering, by contrast, is confined almost entirely to the trailing hemisphere. Most sputtering is done by energetic sulfur ions (100s of keV to MeV), but most of the O2 and H2 production is done by cold oxygen ions (temperature ∼ 100 eV, total energy ∼ 500 eV). As a part of the sputtering rate calculation we compared experimental sputtering yields with analytic estimates. We found that the experimental data are well approximated by the expressions of Famá et al. for ions with energies less than 100 keV (Famá, M., Shi, J., Baragiola, R.A., 2008. Sputtering of ice by low-energy ions. Surf. Sci. 602, 156-161), while the expressions from Johnson et al. fit the data best at higher energies (Johnson, R.E., Burger, M.H., Cassidy, T.A., Leblanc, F., Marconi, M., Smyth, W.H., 2009. Composition and Detection of Europa's Sputter-Induced Atmosphere, in: Pappalardo, R.T., McKinnon, W.B., Khurana, K.K. (Eds.), Europa. University of Arizona Press, Tucson.). We compare the calculated sputtering rate with estimates of water ice regolith grain size as estimated from Galileo Near-Infrared Mapping Spectrometer (NIMS) data, and find that they are strongly correlated as previously suggested by Clark et al. (Clark, R.N., Fanale, F.P., Zent, A.P., 1983. Frost grain size metamorphism: Implications for remote sensing of planetary surfaces. Icarus 56, 233-245.). The mechanism responsible for the sputtering rate/grain size link is uncertain. We also report a surface composition estimate using

  16. Theoretical and Experimental: The Synthetic and Anion-Binding Properties of Tripodal Salicylaldehyde Derivatives

    Directory of Open Access Journals (Sweden)

    Zhong-Jie Xu

    2016-05-01

    Full Text Available A series of colorimetric anion probes 1–6 containing OH and NO2 groups were synthesized, and their recognition properties toward various anions were investigated by visual observation, ultraviolet–visible spectroscopy, fluorescence, 1H nuclear magnetic resonance titration spectra and theoretical investigation. Nanomaterials of three compounds 2–4 were prepared successfully. Four compounds 3–6 that contain electron-withdrawing substituents showed a high binding ability for AcO−. The host–guest complex formed through a 1:1 binding ratio, and color changes were detectable during the recognition process. Theoretical investigation analysis revealed that an intramolecular hydrogen bond existed in the structures of compounds and the roles of molecular frontier orbitals in molecular interplay. These studies suggested that this series of compounds could be used as colorimetric probes to detect of AcO−.

  17. Secondary ion formation during electronic and nuclear sputtering of germanium

    Science.gov (United States)

    Breuer, L.; Ernst, P.; Herder, M.; Meinerzhagen, F.; Bender, M.; Severin, D.; Wucher, A.

    2018-06-01

    Using a time-of-flight mass spectrometer attached to the UNILAC beamline located at the GSI Helmholtz Centre for Heavy Ion Research, we investigate the formation of secondary ions sputtered from a germanium surface under irradiation by swift heavy ions (SHI) such as 5 MeV/u Au by simultaneously recording the mass spectra of the ejected secondary ions and their neutral counterparts. In these experiments, the sputtered neutral material is post-ionized via single photon absorption from a pulsed, intensive VUV laser. After post-ionization, the instrument cannot distinguish between secondary ions and post-ionized neutrals, so that both signals can be directly compared in order to investigate the ionization probability of different sputtered species. In order to facilitate an in-situ comparison with typical nuclear sputtering conditions, the system is also equipped with a conventional rare gas ion source delivering a 5 keV argon ion beam. For a dynamically sputter cleaned surface, it is found that the ionization probability of Ge atoms and Gen clusters ejected under electronic sputtering conditions is by more than an order of magnitude higher than that measured for keV sputtered particles. In addition, the mass spectra obtained under SHI irradiation show prominent signals of GenOm clusters, which are predominantly detected as positive or negative secondary ions. From the m-distribution for a given Ge nuclearity n, one can deduce that the sputtered material must originate from a germanium oxide matrix with approximate GeO stoichiometry, probably due to residual native oxide patches even at the dynamically cleaned surface. The results clearly demonstrate a fundamental difference between the ejection and ionization mechanisms in both cases, which is interpreted in terms of corresponding model calculations.

  18. Low-energy electron-induced dissociation in condensed-phase L-cysteine I: Desorption of anions from chemisorbed films

    International Nuclear Information System (INIS)

    Alizadeh, E; Rowntree, P A; Massey, S; Sanche, L

    2015-01-01

    Among amino acids, cysteine has been widely studied, becoming a standard for molecular self-assembly experiments, because its mercapto group (-SH) allows the formation of self-assembled monolayers (SAMs) on metal surfaces. Dissociative electron attachment (DEA) on L-cysteine SAMs is investigated utilizing a time-of-flight mass spectrometer coupled with a low-energy electron gun. The results show that electrons with kinetic energies of 3 to 15 eV attach to L-cysteine producing anionic fragments of different masses (e.g., H - , O - , OH - , S - , SH - ) via dissociation of intermediate transient anions. The anion yield functions exhibited purely resonant behaviour with electron energies below 15 eV, indicating that the formation of transient anions is the predominant mechanism of production of anionic fragments from L-cysteine dissociation. (paper)

  19. Relation between heat of vaporization, ion transport, molar volume, and cation-anion binding energy for ionic liquids.

    Science.gov (United States)

    Borodin, Oleg

    2009-09-10

    A number of correlations between heat of vaporization (H(vap)), cation-anion binding energy (E(+/-)), molar volume (V(m)), self-diffusion coefficient (D), and ionic conductivity for 29 ionic liquids have been investigated using molecular dynamics (MD) simulations that employed accurate and validated many-body polarizable force fields. A significant correlation between D and H(vap) has been found, while the best correlation was found for -log(DV(m)) vs H(vap) + 0.28E(+/-). A combination of enthalpy of vaporization and a fraction of the cation-anion binding energy was suggested as a measure of the effective cohesive energy for ionic liquids. A deviation of some ILs from the reported master curve is explained based upon ion packing and proposed diffusion pathways. No general correlations were found between the ion diffusion coefficient and molecular volume or the diffusion coefficient and cation/anion binding energy.

  20. Simple model of surface roughness for binary collision sputtering simulations

    Energy Technology Data Exchange (ETDEWEB)

    Lindsey, Sloan J. [Institute of Solid-State Electronics, TU Wien, Floragasse 7, A-1040 Wien (Austria); Hobler, Gerhard, E-mail: gerhard.hobler@tuwien.ac.at [Institute of Solid-State Electronics, TU Wien, Floragasse 7, A-1040 Wien (Austria); Maciążek, Dawid; Postawa, Zbigniew [Institute of Physics, Jagiellonian University, ul. Lojasiewicza 11, 30348 Kraków (Poland)

    2017-02-15

    Highlights: • A simple model of surface roughness is proposed. • Its key feature is a linearly varying target density at the surface. • The model can be used in 1D/2D/3D Monte Carlo binary collision simulations. • The model fits well experimental glancing incidence sputtering yield data. - Abstract: It has been shown that surface roughness can strongly influence the sputtering yield – especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the “density gradient model”) which imitates surface roughness effects. In the model, the target’s atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient – leading to increased sputtering yields, similar in effect to surface roughness.

  1. Simple model of surface roughness for binary collision sputtering simulations

    International Nuclear Information System (INIS)

    Lindsey, Sloan J.; Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

    2017-01-01

    Highlights: • A simple model of surface roughness is proposed. • Its key feature is a linearly varying target density at the surface. • The model can be used in 1D/2D/3D Monte Carlo binary collision simulations. • The model fits well experimental glancing incidence sputtering yield data. - Abstract: It has been shown that surface roughness can strongly influence the sputtering yield – especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the “density gradient model”) which imitates surface roughness effects. In the model, the target’s atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient – leading to increased sputtering yields, similar in effect to surface roughness.

  2. Evaluation of residual stress in sputtered tantalum thin-film

    Energy Technology Data Exchange (ETDEWEB)

    Al-masha’al, Asa’ad, E-mail: asaad.al@ed.ac.uk; Bunting, Andrew; Cheung, Rebecca

    2016-05-15

    Highlights: • Tantalum thin-films have been deposited by DC magnetron sputtering system. • Thin-film stress is observed to be strongly influenced by sputtering pressure. • Transition towards the compressive stress is ascribed to the annealing at 300 °C. • Expose thin-film to air ambient or ion bombardment lead to a noticeable change in the residual stress. - Abstract: The influence of deposition conditions on the residual stress of sputtered tantalum thin-film has been evaluated in the present study. Films have been deposited by DC magnetron sputtering and curvature measurement method has been employed to calculate the residual stress of the films. Transitions of tantalum film stress from compressive to tensile state have been observed as the sputtering pressure increases. Also, the effect of annealing process at temperature range of 90–300 °C in oxygen ambient on the residual stress of the films has been studied. The results demonstrate that the residual stress of the films that have been deposited at lower sputtering pressure has become more compressive when annealed at 300 °C. Furthermore, the impact of exposure to atmospheric ambient on the tantalum film stress has been investigated by monitoring the variation of the residual stress of both annealed and unannealed films over time. The as-deposited films have been exposed to pure Argon energy bombardment and as result, a high compressive stress has been developed in the films.

  3. Water permeation through anion exchange membranes

    Science.gov (United States)

    Luo, Xiaoyan; Wright, Andrew; Weissbach, Thomas; Holdcroft, Steven

    2018-01-01

    An understanding of water permeation through solid polymer electrolyte (SPE) membranes is crucial to offset the unbalanced water activity within SPE fuel cells. We examine water permeation through an emerging class of anion exchange membranes, hexamethyl-p-terphenyl poly (dimethylbenzimidazolium) (HMT-PMBI), and compare it against series of membrane thickness for a commercial anion exchange membrane (AEM), Fumapem® FAA-3, and a series of proton exchange membranes, Nafion®. The HMT-PMBI membrane is found to possess higher water permeabilities than Fumapem® FAA-3 and comparable permeability than Nafion (H+). By measuring water permeation through membranes of different thicknesses, we are able to decouple, for the first time, internal and interfacial water permeation resistances through anion exchange membranes. Permeation resistances on liquid/membrane interface is found to be negligible compared to that for vapor/membrane for both series of AEMs. Correspondingly, the resistance of liquid water permeation is found to be one order of magnitude smaller compared to that of vapor water permeation. HMT-PMBI possesses larger effective internal water permeation coefficient than both Fumapem® FAA-3 and Nafion® membranes (60 and 18% larger, respectively). In contrast, the effective interfacial permeation coefficient of HMT-PMBI is found to be similar to Fumapem® (±5%) but smaller than Nafion®(H+) (by 14%).

  4. Estimates of Sputter Yields of Solar-Wind Heavy Ions of Lunar Regolith Materials

    Science.gov (United States)

    Barghouty, Abdulmasser F.; Adams, James H., Jr.

    2008-01-01

    At energies of approximately 1 keV/amu, solar-wind protons and heavy ions interact with the lunar surface materials via a number of microscopic interactions that include sputtering. Solar-wind induced sputtering is a main mechanism by which the composition of the topmost layers of the lunar surface can change, dynamically and preferentially. This work concentrates on sputtering induced by solar-wind heavy ions. Sputtering associated with slow (speeds the electrons speed in its first Bohr orbit) and highly charged ions are known to include both kinetic and potential sputtering. Potential sputtering enjoys some unique characteristics that makes it of special interest to lunar science and exploration. Unlike the yield from kinetic sputtering where simulation and approximation schemes exist, the yield from potential sputtering is not as easy to estimate. This work will present a preliminary numerical scheme designed to estimate potential sputtering yields from reactions relevant to this aspect of solar-wind lunar-surface coupling.

  5. Molecular dynamic simulation of interaction of low-energy Ar and Xe ions with copper clusters at graphite surface

    International Nuclear Information System (INIS)

    Kornich, G.V.; Lozovskaya, L.I.; Betts, G.; Zaporozhchenko, V.I.; Faupel, F.

    2005-01-01

    One conducted molecular and dynamic simulation of sputtering of isolated clusters consisting of 13, 27 and 195 Cu atoms from the (0001) graphite surface by 200 eV energy Ar and Xe ions. It is shown that the factors of reflection of Ar and Xe ions from copper clusters differ from one another insignificantly, though the energy of the reflected Xe ions is essentially lower than that of Ar ions. The values of the factor of cluster sputtering by Xe ions are higher in contrast to sputtering by Ar ions. One identified two mechanisms of cluster sputtering resulting in the maximum of sputtering intensity at the polar angles near the normal one, and in periodicity of maximums within the azimuth distributions of sputtering intensity with 60 deg period [ru

  6. Ion beam sputter coatings for laser technology

    Science.gov (United States)

    Ristau, Detlev; Gross, Tobias

    2005-09-01

    The initial motivation for the development of Ion Beam Sputtering (IBS) processes was the need for optical coatings with extremely low optical scatter losses for laser gyros. Especially, backscattering of the gyro-mirrors couples the directional modes in the ring resonator leading to the lock in effect which limits the sensitivity of the gyro. Accordingly, the first patent on IBS was approved for an aircraft company (Litton) in 1978. In the course of the rapid development of the IBS-concept during the last two decades, an extremely high optical quality could be achieved for laser coatings in the VIS- and NIR-spectral region. For example, high reflecting coatings with total optical losses below 1 ppm were demonstrated for specific precision measurement applications with the Nd:YAG-laser operating at 1.064 μm. Even though the high quality level of IBS-coatings had been confirmed in many applications, the process has not found its way into the production environment of most optical companies. Major restrictions are the relatively low rate of the deposition process and the poor lateral homogeneity of the coatings, which are related to the output characteristics of the currently available ion sources. In the present contribution, the basic principles of IBS will be discussed in the context of the demands of modern laser technology. Besides selected examples for special applications of IBS, aspects will be presented for approaches towards rapid manufacturing of coatings and the production of rugate filters on the basis of IBS-techniques.

  7. A novel anion exchange membrane from polystyrene (ethylene butylene) polystyrene: Synthesis and characterization

    International Nuclear Information System (INIS)

    Vinodh, Rajangam; Ilakkiya, Arjunan; Elamathi, Swaminathan; Sangeetha, Dharmalingam

    2010-01-01

    We look forward for an eco-friendly hydrocarbon polymer with higher molecular weight for the preparation of an anion exchange membrane. Polystyrene ethylene butylene polystyrene (PSEBS) was chosen as the polymer matrix. The anion exchange membrane was prepared from PSEBS tri-block co-polymer and then the properties were characterized for alkaline fuel cell application. The preparation of anion exchange polymer involved two steps namely chloromethylation and quaternization. The anion exchange membrane with high conductivity has been prepared by introducing quaternary ammonium groups in to the polymer. Finally, the membrane was prepared using solution casting method. The solution casting method yields highly hydrophilic membranes with uniform structure that were suitable for electrochemical applications. The efficiency of the entrapment was monitored by swelling ratio, chemical stability and ion exchange measurement. The characteristic structural properties of the membrane were investigated by FT-IR spectroscopy and 1 H NMR spectroscopy. The thermal stability of the membrane was characterized by TGA, DSC and DMA (dynamic mechanical analysis). The prepared uniform electrolyte membrane in this study has high thermal and chemical stability. The surface morphology and elemental composition of the quaternized PSEBS was determined by SEM-EDXA techniques, respectively. The measured hydroxyl ion conductivity of the synthesized alkaline PSEBS polymer electrolyte membrane showed ionic conductivity in the range of 10 -3 S/cm in deionized water at room temperature. It was found that the substitution provided a flexible, chemically and thermally stable membrane. Hence, the membrane will have potential application in the alkaline fuel cell.

  8. Hydration of a Large Anionic Charge Distribution - Naphthalene-Water Cluster Anions

    Science.gov (United States)

    Weber, J. Mathias; Adams, Christopher L.

    2010-06-01

    We report the infrared spectra of anionic clusters of naphthalene with up to three water molecules. Comparison of the experimental infrared spectra with theoretically predicted spectra from quantum chemistry calculations allow conclusions regarding the structures of the clusters under study. The first water molecule forms two hydrogen bonds with the π electron system of the naphthalene moiety. Subsequent water ligands interact with both the naphthalene and the other water ligands to form hydrogen bonded networks, similar to other hydrated anion clusters. Naphthalene-water anion clusters illustrate how water interacts with negative charge delocalized over a large π electron system. The clusters are interesting model systems that are discussed in the context of wetting of graphene surfaces and polyaromatic hydrocarbons.

  9. The thiocyanate anion is a primary driver of carbon dioxide capture by ionic liquids

    Science.gov (United States)

    Chaban, Vitaly

    2015-01-01

    Carbon dioxide, CO2, capture by room-temperature ionic liquids (RTILs) is a vivid research area featuring both accomplishments and frustrations. This work employs the PM7-MD method to simulate adsorption of CO2 by 1,3-dimethylimidazolium thiocyanate at 300 K. The obtained result evidences that the thiocyanate anion plays a key role in gas capture, whereas the impact of the 1,3-dimethylimidazolium cation is mediocre. Decomposition of the computed wave function on the individual molecular orbitals confirms that CO2-SCN binding extends beyond just expected electrostatic interactions in the ion-molecular system and involves partial sharing of valence orbitals.

  10. Graphene-coated polymeric anion exchangers for ion chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai; Cao, Minyi; Lou, Chaoyan [Department of Chemistry, Xixi Campus, Zhejiang University, Hangzhou 310028 (China); Wu, Shuchao, E-mail: wushch2002@163.com [Zhejiang Institute of Geology and Mineral Resources, Hangzhou 310007 (China); Zhang, Peimin [Department of Chemistry, Xixi Campus, Zhejiang University, Hangzhou 310028 (China); Zhi, Mingyu [Hangzhou Vocational & Technical College, Hangzhou, 310018 (China); Zhu, Yan, E-mail: zhuyan@zju.edu.cn [Department of Chemistry, Xixi Campus, Zhejiang University, Hangzhou 310028 (China)

    2017-06-01

    Carbonaceous stationary phases have gained much attention for their peculiar selectivity and robustness. Herein we report the fabrication and application of a graphene-coated polymeric stationary phase for anion exchange chromatography. The graphene-coated particles were fabricated by a facile evaporation-reduction method. These hydrophilic particles were proven appropriate substrates for grafting of hyperbranched condensation polymers (HBCPs) to make pellicular anion exchangers. The new phase was characterized by zeta potentials, Fourier transform infrared spectroscopy, thermogravimetry and scanning electron microscope. Frontal displacement chromatography showed that the capacities of the anion exchangers were tuned by both graphene amount and HBCPs layer count. The chromatographic performance of graphene-coated anion exchangers was demonstrated with separation of inorganic anions, organic acids, carbohydrates and amino acids. Good reproducibility was obtained by consecutive injections, indicating high chemical stability of the coating. - Highlights: • Graphene-coated polymeric particles were fabricated by a facile method. • Hyperbranched condensation polymers (HBCPs) were grafted from graphene-coated particles to make anion exchangers. • Graphene amount and HBCPs layer count had significant effects on the anion exchange capacities. • Separation of diverse anionic analytes on the anion exchangers was demonstrated. • The prepared anion exchangers exhibited high stability.

  11. Simple model of surface roughness for binary collision sputtering simulations

    Science.gov (United States)

    Lindsey, Sloan J.; Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

    2017-02-01

    It has been shown that surface roughness can strongly influence the sputtering yield - especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the "density gradient model") which imitates surface roughness effects. In the model, the target's atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient - leading to increased sputtering yields, similar in effect to surface roughness.

  12. Energy sharing and sputtering in low-energy collision cascades

    International Nuclear Information System (INIS)

    Weller, R.A.; Weller, M.R.

    1982-01-01

    Using a non-linear transport equation to describe the energy-sharing process in an isotropic collision cascade, we have numerically calculated sputtered particle velocity spectra for several very low energy (=< 10 eV) primary recoil distributions. Our formulation of the sputtering process is essentially that used in the linear model and our equations yield the familiar linear model results in the appropriate limit. Discrepancies between our calculations and the linear model results in other cases may be understood by considering the effects of the linear model assumptions on the sputtering yield at very low energies. Our calculations are also compared with recent experimental results investigating ion-explosion sputtering. The results of this comparison support the conclusion that in insulators sputtering is initiated by very low energy recoil atoms when the energy of the incident beam is high enough that the stopping power is dominated by the electronic contribution. The calculations also suggest that energy spectra similar to those for evaporation may result from non-equilibrium processes but that the apparent temperatures of evaporation are not related in a simple way to any real temperature within the target. (author)

  13. The corrosion and passivity of sputtered Mg–Ti alloys

    International Nuclear Information System (INIS)

    Song, Guang-Ling; Unocic, Kinga A.; Meyer, Harry; Cakmak, Ercan; Brady, Michael P.; Gannon, Paul E.; Himmer, Phil; Andrews, Quinn

    2016-01-01

    Highlights: • A supersaturated single phase Mg–Ti alloy can be obtained by magnetron sputtering. • The anodic dissolution of Mg–Ti alloy is inhibited by Ti addition. • The alloy becomes passive when Ti content is high and the alloy has become Ti based. • The formation of a continuous thin passive film is responsible for the passivation of the alloy. - Abstract: This study explored the possibility of forming a “stainless” Mg–Ti alloy. The electrochemical behavior of magnetron-sputtered Mg–Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg–Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. The surface film that formed on sputtered Mg–Ti based alloys in NaCl solution was thick, discontinuous and non-protective, whereas a thin, continuous and protective Mg and Ti oxide film was formed on a sputtered Ti–Mg based alloy.

  14. Nitinol: Tubing versus sputtered film - microcleanliness and corrosion behavior.

    Science.gov (United States)

    Wohlschlögel, Markus; Lima de Miranda, Rodrigo; Schüßler, Andreas; Quandt, Eckhard

    2016-08-01

    Corrosion behavior and microcleanliness of medical-device grade Nitinol tubing (Nix Ti1- x , x = 0.51; outer diameter 7 mm, wall thickness 0.5 mm), drawn from various ingot qualities, are compared to the characteristics of sputtered Nitinol film material (Nix Ti1- x , x = 0.51; thickness 50 µm). Electropolished tubing half-shell samples are tested versus as-received sputtered film samples. Inclusion size distributions are assessed using quantitative metallography and corrosion behavior is investigated by potentiodynamic polarization testing in phosphate-buffered saline at body temperature. For the sputtered film samples, the surface chemistry is additionally analyzed employing Auger Electron Spectroscopy (AES) composition-depth profiling. Results show that the fraction of breakdowns in the potentiodynamic polarization test correlates with number and size of the inclusions in the material. For the sputtered Nitinol film material no inclusions were detectable by light microscopy on the one hand and no breakdowns were found in the potentiodynamic polarization test on the other hand. As for electropolished Nitinol, the sputtered Nitinol film material reveals Nickel depletion and an Oxygen-to-Titanium intensity ratio of ∼2:1 in the surface oxide layer, as measured by AES. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1176-1181, 2016. © 2015 Wiley Periodicals, Inc.

  15. Infrared Spectroscopy of Discrete Uranyl Anion Complexes

    International Nuclear Information System (INIS)

    Groenewold, G. S.; Gianotto, Anita K.; McIIwain, Michael E.; Van Stipdonk, Michael J.; Kullman, Michael; Moore, David T.; Polfer, Nick; Oomens, Jos; Infante, Ivan A.; Visscher, Lucas; Siboulet, Bertrand; De Jong, Wibe A.

    2008-01-01

    The Free-Electron Laser for Infrared Experiments (FELIX) w 1 as used to study the wavelength-resolved multiple photon photodissociation of discrete, gas phase uranyl (UO2 2 2+) complexes containing a single anionic ligand (A), with or without ligated solvent molecules (S). The uranyl antisymmetric and symmetric stretching frequencies were measured for complexes with general formula [UO2A(S)n]+, where A was either hydroxide, methoxide, or acetate; S was water, ammonia, acetone, or acetonitrile; and n = 0-3. The values for the antisymmetric stretching frequency for uranyl ligated with only an anion ([UO2A]+) were as low or lower than measurements for [UO2]2+ ligated with as many as five strong neutral donor ligands, and are comparable to solution phase values. This result was surprising because initial DFT calculations predicted values that were 30-40 cm-1 higher, consistent with intuition but not with the data. Modification of the basis sets and use of alternative functionals improved computational accuracy for the methoxide and acetate complexes, but calculated values for the hydroxide were greater than the measurement regardless of the computational method used. Attachment of a neutral donor ligand S to [UO2A]+ produced [UO2AS]+, which produced only very modest changes to the uranyl antisymmetric stretch frequency, and did not universally shift the frequency to lower values. DFT calculations for [UO2AS]+ were in accord with trends in the data, and showed that attachment of the solvent was accommodated by weakening of the U-anion bond as well as the uranyl. When uranyl frequencies were compared for [UO2AS]+ species having different solvent neutrals, values decreased with increasing neutral nucleophilicity

  16. Process for removing sulfate anions from waste water

    Science.gov (United States)

    Nilsen, David N.; Galvan, Gloria J.; Hundley, Gary L.; Wright, John B.

    1997-01-01

    A liquid emulsion membrane process for removing sulfate anions from waste water is disclosed. The liquid emulsion membrane process includes the steps of: (a) providing a liquid emulsion formed from an aqueous strip solution and an organic phase that contains an extractant capable of removing sulfate anions from waste water; (b) dispersing the liquid emulsion in globule form into a quantity of waste water containing sulfate anions to allow the organic phase in each globule of the emulsion to extract and absorb sulfate anions from the waste water and (c) separating the emulsion including its organic phase and absorbed sulfate anions from the waste water to provide waste water containing substantially no sulfate anions.

  17. Recent advancements in sputter-type heavy negative ion sources

    International Nuclear Information System (INIS)

    Alton, G.D.

    1989-01-01

    Significant advancement have been made in sputter-type negative ion sources which utilize direct surface ionization, or a plasma to form the positive ion beam used to effect sputtering of samples containing the material of interest. Typically, such sources can be used to generate usable beam intensities of a few μA to several mA from all chemically active elements, depending on the particular source and the electron affinity of the element in question. The presentation will include an introduction to the fundamental processes underlying negative ion formation by sputtering from a low work function surface and several sources will be described which reflect the progress made in this technology. 21 refs., 9 figs., 1 tab

  18. Angular distributions of sputtered particles from NiTi alloy

    International Nuclear Information System (INIS)

    Neshev, I.; Hamishkeev, V.; Chernysh, V.S.; Postnikov, S.; Mamaev, B.

    1993-01-01

    The angular distributions of sputtered Ni and Ti from a polycrystalline NiTi (50-50%) alloy are investigated by Auger electron spectroscopy and Rutherford backscattering spectroscopy. A difference in the angular distributions is observed with Ni being sputtered preferentially near the surface normal. A computer program for the calculation of the angular distributions of constituents sputtered from binary targets is created and used. The mechanisms responsible for the observed differences in the angular distributions are discussed. It is found that the collisional cascade theory is not directly applicable to the results of the constituents' angular distributions obtained in the presence of oxygen. The fitted coefficients of bombardment-induced segregation are found to be greater than the experimentally obtained ones. (author)

  19. Sputtering of amorphous carbon layers studied by laser induced fluorescence

    International Nuclear Information System (INIS)

    Pasch, E.

    1992-07-01

    In order to minimize the radiation losses, it is desirable to keep the plasmas in nuclear fusion devices free of high-Z-impurities. Therefore, the walls of TEXTOR and other tokamaks are covered with thin layers of amorphous carbon layers (a-C:H) or amorphous carbon/boron layers (a-C/B:H). The sputtering behaviour of these layers has been studied under bombardment by Ar + ions with energies of 1.5 keV and current densities of a few mA/cm 2 . Investigations of these coatings were carried out with the object to measure the velocity distribution of the sputtered atoms and the sputtered yields by laser induced fluorescence in the vacuum ultraviolet. (orig.)

  20. Combined sputtering yield and surface topography development studies on Si

    International Nuclear Information System (INIS)

    Carter, G.; Nobes, M.J.; Lewis, G.W.; Whitton, J.L.

    1981-01-01

    The sputtering yield-incidence angle function has been measured for 8 keV Ar + ions incident on Si by direct scanning electron microscope observation of the depths of sputtered craters on substrate boundaries. This function displays a maximum sputtering yield at an angle thetasub(p) approximately equal to 40 0 to the surface normal. The sequential ion fluence dependence of features developed beneath local surface contaminant was then studied, quasi dynamically, in the same on-line ion source-S.E.M. system. During erosion of the contaminant a steeply elevated pillar of Si forms, which then transforms to a cone, again of high elevation angle >>thetasub(p). This cone is gradually eroded into the surrounding surface with no special significance associated with orientations of angle thetasub(p). Pedal depressions surrounding the pillar-cone system are also noted. The reasons for these observations and their relevance to ion beam surface channel etching are discussed. (Auth.)

  1. Measurements of sputtering yields for low-energy plasma ions

    International Nuclear Information System (INIS)

    Nishi, M.; Yamada, M.; Suckewer, S.; Rosengaus, E.

    1979-04-01

    Sputtering yields of various wall/limiter materials of fusion devices have been extensively measured in the relevant plasma environment for low-energy light ions (E 14 cm -3 and electron temperature up to 10eV. Target materials used were C (graphite), Ti, Mo, Ta, W, and Fe (stainless steel). In order to study the dependence of the sputtering yields on the incident energy of ions, the target samples were held at negative bias voltage up to 300V. The sputtering yields were determined by a weight-loss method and by spectral line intensity measurements. The data obtained in the present experiment agree well with those previously obtained at the higher energies (E greater than or equal to 200eV) by other authors using different schemes; the present data also extend to substantially lower energies (E approx. > 30eV) than hitherto

  2. Carbon Back Sputter Modeling for Hall Thruster Testing

    Science.gov (United States)

    Gilland, James H.; Williams, George J.; Burt, Jonathan M.; Yim, John T.

    2016-01-01

    In support of wear testing for the Hall Effect Rocket with Magnetic Shielding (HERMeS) program, the back sputter from a Hall effect thruster plume has been modeled for the NASA Glenn Research Centers Vacuum Facility 5. The predicted wear at a near-worst case condition of 600 V, 12.5 kW was found to be on the order of 3 4 mkhour in a fully carbon-lined chamber. A more detailed numerical monte carlo code was also modified to estimate back sputter for a detailed facility and pumping configuration. This code demonstrated similar back sputter rate distributions, but is not yet accurately modeling the magnitudes. The modeling has been benchmarked to recent HERMeS wear testing, using multiple microbalance measurements. These recent measurements have yielded values, on the order of 1.5- 2 microns/khour.

  3. RF Magnetron Sputtering Coating Of Hydroxyapatite On Alkali Solution Treated Titanate Nanorods

    Directory of Open Access Journals (Sweden)

    Lee K.

    2015-06-01

    Full Text Available Hydroxyapatite (HA is a material with outstanding biocompatibility. It is chemically similar to natural bone tissue, and has therefore been favored for use as a coating material for dental and orthopedic implants. In this study, RF magnetron sputtering was applied for HA coating. And Alkali treatment was performed in a 5 M NaOH solution at 60°C. The coated HA thin film was heat-treated at a range of temperatures from 300 to 600°C. The morphological characterization and crystal structures of the coated specimens were then obtained via FE-SEM, XRD, and FT-IR. The amorphous thin film obtained on hydrothermally treated nanorods transformed into a crystalline thin film after the heat treatment. The change in the phase transformation, with an enhanced crystallinity, showed a reduced wettability. The hydrothermally treated nanorods with an amorphous thin film, on the other hand, showed an outstanding wettability. The HA thin film perpendicularly coated the nanorods in the upper and inner parts via RF magnetron sputtering, and the FT-IR results confirmed that the molecular bonding of the coated film had an HA structure.

  4. Fabrication of high-quality single-crystal Cu thin films using radio-frequency sputtering.

    Science.gov (United States)

    Lee, Seunghun; Kim, Ji Young; Lee, Tae-Woo; Kim, Won-Kyung; Kim, Bum-Su; Park, Ji Hun; Bae, Jong-Seong; Cho, Yong Chan; Kim, Jungdae; Oh, Min-Wook; Hwang, Cheol Seong; Jeong, Se-Young

    2014-08-29

    Copper (Cu) thin films have been widely used as electrodes and interconnection wires in integrated electronic circuits, and more recently as substrates for the synthesis of graphene. However, the ultra-high vacuum processes required for high-quality Cu film fabrication, such as molecular beam epitaxy (MBE), restricts mass production with low cost. In this work, we demonstrated high-quality Cu thin films using a single-crystal Cu target and radio-frequency (RF) sputtering technique; the resulting film quality was comparable to that produced using MBE, even under unfavorable conditions for pure Cu film growth. The Cu thin film was epitaxially grown on an Al2O3 (sapphire) (0001) substrate, and had high crystalline orientation along the (111) direction. Despite the 10(-3) Pa vacuum conditions, the resulting thin film was oxygen free due to the high chemical stability of the sputtered specimen from a single-crystal target; moreover, the deposited film had >5× higher adhesion force than that produced using a polycrystalline target. This fabrication method enabled Cu films to be obtained using a simple, manufacturing-friendly process on a large-area substrate, making our findings relevant for industrial applications.

  5. Well-Defined Polyethylene-Based Random, Block, and Bilayered Molecular Cobrushes

    KAUST Repository

    Zhang, Hefeng; Zhang, Zhen; Gnanou, Yves; Hadjichristidis, Nikolaos

    2015-01-01

    by anionic polymerization. Proton nuclear magnetic resonance spectroscopy (1H NMR) and high-temperature gel permeation chromatography (HT-GPC) were used to imprint the molecular characteristics of all macromonomers and molecular brushes and differential

  6. Anion photoelectron spectroscopy of radicals and clusters

    Energy Technology Data Exchange (ETDEWEB)

    Travis, Taylor R. [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying 2Σ and 2π states of C2nH (n = 1--4) have been studied. The anion photoelectron spectra yielded electron affinities, term values, and vibrational frequencies for these combustion and astrophysically relevant species. Photoelectron angular distributions allowed the author to correctly assign the electronic symmetry of the ground and first excited states and to assess the degree of vibronic coupling in C2H and C4H. Other radicals studied include NCN and I3. The author was able to observe the low-lying singlet and triplet states of NCN for the first time. Measurement of the electron affinity of I3 revealed that it has a bound ground state and attachment of an argon atom to this moiety enabled him to resolve the symmetric stretching progression.

  7. Arc generation from sputtering plasma-dielectric inclusion interactions

    International Nuclear Information System (INIS)

    Wickersham, C.E. Jr.; Poole, J.E.; Fan, J.S.

    2002-01-01

    Arcing during sputter deposition and etching is a significant cause of particle defect generation during device fabrication. In this article we report on the effect of aluminum oxide inclusion size, shape, and orientation on the propensity for arcing during sputtering of aluminum targets. The size, shape, and orientation of a dielectric inclusion plays a major role in determining the propensity for arcing and macroparticle emission. In previous studies we found that there is a critical inclusion size required for arcing to occur. In this article we used high-speed videos, electric arc detection, and measurements of particle defect density on wafers to study the effect of Al 2 O 3 inclusion size, shape, and orientation on arc rate, intensity, and silicon wafer particle defect density. We found that the cross-sectional area of the inclusion exposed to the sputtering plasma is the critical parameter that determines the arc rate and rate of macroparticle emission. Analysis of the arc rate, particle defect density, and the intensity of the optical emission from the arcing plasma indicates that the critical aluminum oxide inclusion area for arcing is 0.22±0.1 mm2 when the sputtering plasma sheath dark-space λ d , is 0.51 mm. Inclusions with areas greater than this critical value readily induce arcing and macroparticle ejection during sputtering. Inclusions below this critical size do not cause arcing or macroparticle ejection. When the inclusion major axis is longer than 2λ d and lies perpendicular to the sputter erosion track tangent, the arcing activity increases significantly over the case where the inclusion major axis lies parallel to the erosion track tangent

  8. Anion concurrence and anion selectivity in the sorption of radionuclides by organotones

    International Nuclear Information System (INIS)

    Behnsen, Julia G.

    2007-01-01

    Some long-lived and radiologically important nuclear fission products, such as I-129 (half-life t 1/2 = 1,6 . 10 7 a), Tc-99 (t 1/2 = 2,1 . 10 5 a), and Se-79 (t 1/2 = 6,5 . 10 4 a) are anionic in aqueous environments. This study focuses on the adsorption of such anions to organoclays and the understanding of the selectivity of the process. The organoclays used in this study were prepared from a bentonite (MX-80) and a vermiculite clay, and the cationic surfactants hexadcylpyridium, hexadecyltrimethylammonium, and benzethonium. Surfactant adsorption to the bentonite exceeds the cation exchange capacity of the clay, with the surplus positive charge being balanced by the co-adsorption of chloride. The interlayer distance of the bentonites is increased sufficiently to contain bi- and pseudotrimolecular structures of the surfactants. Adsorption experiments were carried out using the batch technique. Anion adsorption of iodide, perrhenate, selenite, nitrate, and sulphate is mainly due to ion exchange with chloride. As an additional adsorption mechanism, the incorporation of inorganic ion pairs into the interlayer space of the clay is proposed as a result of experiments showing differences in the adsorption levels of sodium and potassium iodide. Anion adsorption results show a clear selectivity of the organoclays, with the affinity sequence being: ReO - 4 > I - > NO - 3 > Cl - > SO 2- 4 > SeO 2- 3 . This sequence corresponds to the sequence of increasing hydration energies of the anions, thus selectivity could be due to the process of minimization of free energy of the system. (orig.)

  9. Rf reactive sputtering of indium-tin-oxide films

    International Nuclear Information System (INIS)

    Tvarozek, V.; Novotny, I.; Harman, R.; Kovac, J.

    1986-01-01

    Films of indium-tin-oxide (ITO) have been deposited by rf reactive diode sputtering of metallic InSn alloy targets, or ceramic ITO targets, in an Ar and Ar+0 2 atmosphere. Electrical as well as optical properties of ITO films were controlled by varying sputtering parameters and by post-deposition heat-treatment in Ar, H 2 , N 2 , H 2 +N 2 ambients. The ITO films exhibited low resistivity approx. 2 x 10 -4 Ω cm, high transmittance approx. 90% in the visible spectral region and high reflectance approx. 80% in the near infra-red region. (author)

  10. Mechanical and structural properties of sputtered Ni/Ti multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Senthil Kumar, M.; Boeni, P.; Tixier, S.; Clemens, D.; Horisberger, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Ni/Ti bilayers have been prepared by dc-magnetron sputtering in order to study their mechanical and structural properties. A remarkable reduction of stress is observed when the Ni layers are sputtered reactively in argon with a high partial pressure of air. The high angle x-ray diffraction studies show a tendency towards amorphisation of the Ni layers with increasing air flow. The low angle measurements indicate a substantial reduction of interdiffusion resulting in smoother interfaces with increasing air content. (author) 2 figs., 2 refs.

  11. High power impulse magnetron sputtering and its applications

    Science.gov (United States)

    Yan, YUAN; Lizhen, YANG; Zhongwei, LIU; Qiang, CHEN

    2018-04-01

    High power impulse magnetron sputtering (HiPIMS) has attracted a great deal of attention because the sputtered material is highly ionized during the coating process, which has been demonstrated to be advantageous for better quality coating. Therefore, the mechanism of the HiPIMS technique has recently been investigated. In this paper, the current knowledge of HiPIMS is described. We focus on the mechanical properties of the deposited thin film in the latest applications, including hard coatings, adhesion enhancement, tribological performance, and corrosion protection layers. A description of the electrical, optical, photocatalytic, and functional coating applications are presented. The prospects for HiPIMS are also discussed in this work.

  12. Nanoporous zinc oxide films prepared by magnetron sputtering

    International Nuclear Information System (INIS)

    Ghimpu, L.; Lupan, O.; Popescu, L.; Tiginyanu, I.M.

    2011-01-01

    In this paper we demonstrate an inexpensive approach for the fabrication of nanoporous zinc oxide films by using magnetron sputtering. Study of the structural properties proves the crystallographic perfection of porous nanostructures and the possibility of its controlling by adjusting the technological parameters in the growth process. The XRD pattern of nanoporous ZnO films exhibits high intensity of the peaks relative to the background signal which is indicative of the ZnO hexagonal phase and a good crystallinity of the samples grown by magnetron sputtering.

  13. Heteroepitaxial Ge-on-Si by DC magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Martin Steglich

    2013-07-01

    Full Text Available The growth of Ge on Si(100 by DC Magnetron Sputtering at various temperatures is studied by Spectroscopic Ellipsometry and Transmission Electron Microscopy. Smooth heteroepitaxial Ge films are prepared at relatively low temperatures of 380°C. Typical Stransky-Krastanov growth is observed at 410°C. At lower temperatures (320°C, films are essentially amorphous with isolated nanocrystallites at the Si-Ge interface. A minor oxygen contamination at the interface, developing after ex-situ oxide removal, is not seen to hinder epitaxy. Compensation of dislocation-induced acceptors in Ge by sputtering from n-doped targets is proposed.

  14. Plasma diagnostics during magnetron sputtering of aluminum doped zinc oxide

    DEFF Research Database (Denmark)

    Stamate, Eugen; Crovetto, Andrea; Sanna, Simone

    2016-01-01

    Plasma parameters during magnetron sputtering of aluminum-doped zinc oxide are investigated with optical emission spectroscopy, electrostatic probes and mass spectrometry with the aim of understanding the role of negative ions of oxygen during the film growth and improving the uniformity of the f......Plasma parameters during magnetron sputtering of aluminum-doped zinc oxide are investigated with optical emission spectroscopy, electrostatic probes and mass spectrometry with the aim of understanding the role of negative ions of oxygen during the film growth and improving the uniformity...

  15. Highly aligned carbon nanotube arrays fabricated by bias sputtering

    International Nuclear Information System (INIS)

    Hayashi, Nobuyuki; Honda, Shin-ichi; Tsuji, Keita; Lee, Kuei-Yi; Ikuno, Takashi; Fujimoto, Keiichi; Ohkura, Shigeharu; Katayama, Mitsuhiro; Oura, Kenjiro; Hirao, Takashi

    2003-01-01

    Vertically aligned carbon nanotube (CNT) arrays have been successfully grown on Si substrates by dc bias sputtering. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that the resultant arrays consisted of dense CNTs with diameters of 40-60 nm and lengths of 300-400 nm. The CNTs were found to have a bamboo-like structure at the end of which metallic nanoparticle was formed, indicating tip growth mechanism. The energy enhancement of carbon particles is a key factor for synthesis of CNTs using dc bias sputtering system

  16. Extended incident-angle dependence formula of sputter yield

    International Nuclear Information System (INIS)

    Ono, T.; Shibata, K.; Muramoto, T.; Kenmotsu, T.; Li Z.; Kawamura, T.

    2006-06-01

    We extend a new semi-empirical formula for incident-angle dependence of normalized sputter yield that includes the contribution to sputter yield from the direct knock-out process that was not considered in the previously proposed one. Three parameters included in the new one are estimated for data calculated with ACAT code for D + ions incident obliquely on C, Fe and W materials in incident-energy regions from several tens of eV to 10 keV. Then, the parameters are expressed with functions of incident energy. The formula with the functions derived well reproduces that using the ACAT data in the whole energy range. (author)

  17. Development of surface relief on polycrystalline metals due to sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Voitsenya, V.S. [IPP NSC KIPT, 61108 Kharkov (Ukraine); Balden, M. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (Germany); Bardamid, A.F. [Taras Shevchenko National University, 01033 Kiev (Ukraine); Bondarenko, V.N. [IPP NSC KIPT, 61108 Kharkov (Ukraine); Davis, J.W., E-mail: jwdavis@starfire.utias.utoronto.ca [University of Toronto Institute for Aerospace Studies, 4925 Dufferin St., Toronto, ON, Canada M3H5T6 (Canada); Konovalov, V.G.; Ryzhkov, I.V.; Skoryk, O.O.; Solodovchenko, S.I. [IPP NSC KIPT, 61108 Kharkov (Ukraine); Zhang-jian, Zhou [University of Science and Technology Beijing, Beijing 100 083 (China)

    2013-05-01

    The characteristics of surface microrelief that appear in sputtering experiments with polycrystalline metals of various grain sizes have been studied. Specimens with grain sizes varying from 30–70 nm in the case of crystallized amorphous alloys, to 1–3 μm for technical tungsten grade and 10–100 μm for recrystallized tungsten were investigated. A model is proposed for the development of roughness on polycrystalline metals which is based on the dependence of sputtering rate on crystal orientation. The results of the modeling are in good agreement with experiments showing that the length scale of roughness is much larger than the grain size.

  18. Inhibition of nuclear waste solutions containing multiple aggressive anions

    International Nuclear Information System (INIS)

    Congdon, J.W.

    1987-01-01

    The inhibition of localized corrosion of carbon steel in caustic, high-level radioactive waste solutions was studied using cyclic potentiodynamic polarization scans, supplemented by partially immersed coupon tests. The electrochemical tests provided a rapid and accurate means of determining the relationship between the minimum inhibitor requirements and the concentration of the aggressive anions in this system. Nitrate, sulfate, chloride, and fluoride were identified as aggressive anions, however, no synergistic effects were observed between these anions. This observation may have important theoretical implications because it tends to contradict the behavior of aggressive anions as predicted by existing theories for localized corrosion. 10 refs., 5 figs., 2 tabs

  19. Comparative study of nanocomposites prepared by pulsed and dc sputtering combined with plasma polymerization suitable for photovoltaic device applications

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Amreen A. [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Pal, Arup R., E-mail: arpal@iasst.gov.in [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Kar, Rajib [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai (India); Bailung, Heremba; Chutia, Joyanti [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam (India); Patil, Dinkar S. [Laser and Plasma Technology Division, Bhabha Atomic Research Center, Trombay, Mumbai (India)

    2014-12-15

    Plasma processing, a single step method for production of large area composite films, is employed to deposit plasma polymerized aniline-Titanium dioxide (PPani-TiO{sub 2}) nanocomposite thin films. The deposition of PPani-TiO{sub 2} nanocomposite films are made using reactive magnetron sputtering and plasma polymerization combined process. This study focuses on the direct comparison between continuous and pulsed dc magnetron sputtering techniques of titanium in combination with rf plasma polymerization of aniline. The deposited PPani-TiO{sub 2} nanocomposite films are characterized and discussed in terms of structural, morphological and optical properties. A self powered hybrid photodetector has been developed by plasma based process. The proposed method provides a new route where the self-assembly of molecules, that is, the spontaneous association of atomic or molecular building blocks under plasma environment, emerge as a successful strategy to form well-defined structural and morphological units of nanometer dimensions. - Highlights: • PPani-TiO{sub 2} nanocomposite by pulsed and dc sputtering with rf plasma polymerization. • In-situ and Ex-situ H{sub 2}SO{sub 4} doping in PPani-TiO{sub 2} nanocomposite. • PPani-TiO{sub 2} nanocomposite based self-powered-hybrid photodetector.

  20. Comparative study of nanocomposites prepared by pulsed and dc sputtering combined with plasma polymerization suitable for photovoltaic device applications

    International Nuclear Information System (INIS)

    Hussain, Amreen A.; Pal, Arup R.; Kar, Rajib; Bailung, Heremba; Chutia, Joyanti; Patil, Dinkar S.

    2014-01-01

    Plasma processing, a single step method for production of large area composite films, is employed to deposit plasma polymerized aniline-Titanium dioxide (PPani-TiO 2 ) nanocomposite thin films. The deposition of PPani-TiO 2 nanocomposite films are made using reactive magnetron sputtering and plasma polymerization combined process. This study focuses on the direct comparison between continuous and pulsed dc magnetron sputtering techniques of titanium in combination with rf plasma polymerization of aniline. The deposited PPani-TiO 2 nanocomposite films are characterized and discussed in terms of structural, morphological and optical properties. A self powered hybrid photodetector has been developed by plasma based process. The proposed method provides a new route where the self-assembly of molecules, that is, the spontaneous association of atomic or molecular building blocks under plasma environment, emerge as a successful strategy to form well-defined structural and morphological units of nanometer dimensions. - Highlights: • PPani-TiO 2 nanocomposite by pulsed and dc sputtering with rf plasma polymerization. • In-situ and Ex-situ H 2 SO 4 doping in PPani-TiO 2 nanocomposite. • PPani-TiO 2 nanocomposite based self-powered-hybrid photodetector

  1. Probing the early stages of salt nucleation—Experimental and theoretical investigations of sodium/potassium thiocyanate cluster anions

    Science.gov (United States)

    Deng, S. H. M.; Kong, Xiang-Yu; Wang, Xue-Bin

    2015-01-01

    clusters were suppressed. The series of anion clusters investigated here range from molecular-like M 1 (SCN)2 - to nano-sized K 22 (SCN)25 3 - , providing a vivid molecular-level growth pattern reflecting the initial salt nucleation process.

  2. Influence of R.F. sputter parameters on the magnetic orientation of Co-Cr layers

    NARCIS (Netherlands)

    Lodder, J.C.; Wielinga, T.

    1984-01-01

    Co-Cr layers for the perpendicular recording mode were deposited by means of RF-sputtering. The most important sputter parameters, i.e. the RF sputter high voltage VRF, the argon pressure Par and the substrate holder temperature Tsh, gave an optimum value for perpendicular orientation of the

  3. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    OpenAIRE

    Rafieian Boroujeni, Damon; Ogieglo, Wojciech; Savenije, Tom; Lammertink, Rob G.H.

    2015-01-01

    We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx

  4. Fluorescence anisotropy of tyrosinate anion using one-, two- and three-photon excitation: tyrosinate anion fluorescence.

    Science.gov (United States)

    Kierdaszuk, Borys

    2013-03-01

    We examined the emission spectra and steady-state anisotropy of tyrosinate anion fluorescence with one-photon (250-310 nm), two-photon (570-620 nm) and three-photon (750-930 nm) excitation. Similar emission spectra of the neutral (pH 7.2) and anionic (pH 13) forms of N-acetyl-L-tyrosinamide (NATyrA) (pKa 10.6) were observed for all modes of excitation, with the maxima at 302 and 352 nm, respectively. Two-photon excitation (2PE) and three-photon excitation (3PE) spectra of the anionic form were the same as that for one-photon excitation (1PE). In contrast, 2PE spectrum from the neutral form showed ~30-nm shift to shorter wavelengths relative to 1PE spectrum (λmax 275 nm) at two-photon energy (550 nm), the latter being overlapped with 3PE spectrum, both at two-photon energy (550 nm). Two-photon cross-sections for NATyrA anion at 565-580 nm were 10 % of that for N-acetyl-L-tryptophanamide (NATrpA), and increased to 90 % at 610 nm, while for the neutral form of NATyrA decreased from 2 % of that for NATrpA at 570 nm to near zero at 585 nm. Surprisingly, the fundamental anisotropy of NATyrA anion in vitrified solution at -60 °C was ~0.05 for 2PE at 610 nm as compared to near 0.3 for 1PE at 305 nm, and wavelength-dependence appears to be a basic feature of its anisotropy. In contrast, the 3PE anisotropy at 900 nm was about 0.5, and 3PE and 1PE anisotropy values appear to be related by the cos(6) θ to cos(2) θ photoselection factor (approx. 10/6) independently of excitation wavelength. Attention is drawn to the possible effect of tyrosinate anions in proteins on their multi-photon induced fluorescence emission and excitation spectra as well as excitation anisotropy spectra.

  5. Once upon Anion: A Tale of Photodetachment

    Science.gov (United States)

    Lineberger, W. Carl

    2013-04-01

    This contribution is very much a personal history of a journey through the wonderful world of anion chemistry, and a tale of how advances in laser technologies, theoretical methods, and computational capabilities continuously enabled advances in our understanding. It is a story of the excitement and joy that come from the opportunity to add to the fabric of science, and to do so by working as a group of excited explorers with common goals. The participants in this journey include me, my students and postdoctoral associates, my collaborators, and our many generous colleagues. It all happened, in the words of the Beatles, “with a little help from my friends.” Actually, it was so much more than a little help!

  6. Adsorption of an anionic dispersant on lignite

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, R.; Kucukbayrak, S. [Istanbul Technical University, Istanbul (Turkey). Dept. of Chemical Engineering, Chemical & Metallurgical Engineering Faculty

    2001-12-01

    Since coal is not a homogeneous substance but a mixture of carbonaceous materials and mineral matter, it has a variety of surface properties. Therefore, it is not easy to control the properties of coal suspensions by simply adjusting variables, such as pH and/or electrolyte. A chemical agent needs to be added to control the properties of the coal suspensions. The adsorption behavior of an anionic dispersant in the presence of a wetting agent using some Turkish lignite samples was investigated. The effects of dispersant concentration, temperature and pH on the dispersant adsorption were studied systematically, and the experimental results are presented. Pellupur B69 as a dispersant, commercial mixture of formaldehyde condensate sodium salt of naphthalene sulphonic acid, and Texapon N{sub 2}5 as a wetting agent, a sodium lauryl ether sulfate, have been used.

  7. Structures and properties of anionic clay minerals

    International Nuclear Information System (INIS)

    Koch, Chr. Bender

    1998-01-01

    The Moessbauer spectra of pyroaurite-sjoegrenite-type compounds (PTC) (layered anion exchangers) are discussed with reference to the crystal structure, cation order, and crystallite morphology. It is shown that cation-ordered layers are produced in the synthesis of carbonate and sulphate types of green rust. In contrast, synthetic and natural pyroaurite only occurs as disordered types. The redox chemistry of Fe(III) within the metal hydroxide layer is illustrated with examples of electrochemical oxidation and reversible reduction by boiling glycerol. The chemistry of iron in the interlayer is exemplified by the intercalation of Fe-cyanide complexes in hydrotalcite. This reaction may be used as a probe for the charge distribution in the interlayer

  8. Advanced polymer chemistry of organometallic anions

    International Nuclear Information System (INIS)

    Chamberlin, R.M.; Abney, K.D.; Balaich, G.J.; Fino, S.A.

    1997-01-01

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of the project was to prepare and characterize new polymers incorporating cobalt dicarbollide. Specific goals were to prepare polymerizable cobalt dicarbollide monomers using the nucleophilic substitution route discovered in laboratories and to establish the reaction conditions required to form polymers from these complexes. This one-year project resulted in two publications (in press), and provided the foundation for further investigations into polymer synthesis and characterization using cobalt dicarbollide and other metallocarboranes. Interest in synthesizing organometallic polymers containing the cobalt bis(dicarbollide) anion is motivated by their possible application as cation exchange materials for the remediation of cesium-137 and strontium-90 from nuclear wastes

  9. Effects of arginine on multimodal anion exchange chromatography.

    Science.gov (United States)

    Hirano, Atsushi; Arakawa, Tsutomu; Kameda, Tomoshi

    2015-12-01

    The effects of arginine on binding and elution properties of a multimodal anion exchanger, Capto adhere, were examined using bovine serum albumin (BSA) and a monoclonal antibody against interleukin-8 (mAb-IL8). Negatively charged BSA was bound to the positively charged Capto adhere and was readily eluted from the column with a stepwise or gradient elution using 1M NaCl at pH 7.0. For heat-treated BSA, small oligomers and remaining monomers were also eluted using a NaCl gradient, whereas larger oligomers required arginine for effective elution. The positively charged mAb-IL8 was bound to Capto adhere at pH 7.0. Arginine was also more effective for elution of the bound mAb-IL8 than was NaCl. The results imply that arginine interacts with the positively charged Capto adhere. The mechanism underlying the interactions of arginine with Capto adhere was examined by calculating the binding free energy between an arginine molecule and a Capto adhere ligand in water through molecular dynamics simulations. The overall affinity of arginine for Capto adhere is attributed to the hydrophobic and π-π interactions between an arginine side chain and the aromatic moiety of the ligand as well as hydrogen bonding between arginine and the ligand hydroxyl group, which may account for the characteristics of protein elution using arginine. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Gamma radiation effect on gas production in anion exchange resins

    Energy Technology Data Exchange (ETDEWEB)

    Traboulsi, A. [CEA Marcoule, DEN/DTCD/SPDE/LCFI, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); E.A. LISA – METICA, Aix Marseille Université, Pôle de l’Etoile, case 451, 13397 Marseille Cedex 20 (France); Labed, V., E-mail: veronique.labed@cea.fr [CEA Marcoule, DEN/DTCD/SPDE/LCFI, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Dauvois, V. [CEA Saclay, DEN/DANS/DPC/SECR/LSRM, 91191 Gif sur Yvette Cedex (France); Dupuy, N.; Rebufa, C. [E.A. LISA – METICA, Aix Marseille Université, Pôle de l’Etoile, case 451, 13397 Marseille Cedex 20 (France)

    2013-10-01

    Radiation-induced decomposition of Amberlite IRA400 anion exchange resin in hydroxide form by gamma radiolysis has been studied at various doses in different atmospheres (anaerobic, anaerobic with liquid water, and aerobic). The effect of these parameters on the degradation of ion exchange resins is rarely investigated in the literature. We focused on the radiolysis gases produced by resin degradation. When the resin was irradiated under anaerobic conditions with liquid water, the liquid phase over the resin was also analyzed to identify any possible water-soluble products released by degradation of the resin. The main products released are trimethylamine (TMA), molecular hydrogen (H{sub 2g}) and carbon dioxide (CO{sub 2g}). TMA and H{sub 2g} are produced in all the irradiation atmospheres. However, TMA was in gaseous form under anaerobic and aerobic conditions and in aqueous form in presence of liquid water. In the latter conditions, TMA{sub aq} was associated with aqueous dimethylamine (DMA{sub aq}), monomethylamine (MMA{sub aq}) and ammonia (NH{sub 4}{sup +}{sub aq}). CO{sub 2g} is formed in the presence of oxygen due to oxidation of organic compounds present in the system, in particular the degradation products such as TMA{sub g}.

  11. Sputtering of solid deuterium by He-ions

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  12. Towards a magnetic field separation in Ion Beam Sputtering processes

    Energy Technology Data Exchange (ETDEWEB)

    Malobabic, Sina, E-mail: s.malobabic@lzh.de [Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover (Germany); Quest: Centre of Quantum Engineering and Space-Time Research, Leibniz Universität Hannover (Germany); Jupé, Marco [Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover (Germany); Quest: Centre of Quantum Engineering and Space-Time Research, Leibniz Universität Hannover (Germany); Kadhkoda, Puja [Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover (Germany); Ristau, Detlev [Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover (Germany); Quest: Centre of Quantum Engineering and Space-Time Research, Leibniz Universität Hannover (Germany)

    2015-10-01

    Defects embedded in coatings due to particle contamination are considered as a primary factor limiting the quality of optical coatings in Ion Beam Sputtering. An approach combining the conventional Ion Beam Sputtering process with a magnetic separator in order to remove these particles from film growth is presented. The separator provides a bent axial magnetic field that guides the material flux towards the substrate positioned at the exit of the separator. Since there is no line of sight between target and substrate, the separator prevents that the particles generated in the target area can reach the substrate. In this context, optical components were manufactured that reveal a particle density three times lower than optical components which were deposited using a conventional Ion Beam Sputtering process. - Highlights: • We use bent magnetic fields to guide and separate the sputtered deposition material. • No line of sight between substrate and target prevents thin films from particles. • The transport efficiency of binary and ternary oxides is investigated. • The defect statistics of manufactured dielectric ternary multilayers are evaluated. • The phase separation leads to a drastically reduction of particle contamination.

  13. Modular design of AFM probe with sputtered silicon tip

    DEFF Research Database (Denmark)

    Rasmussen, Peter; Thaysen, Jacob; Bouwstra, Siebe

    2001-01-01

    of the thin films constituting the cantilever. The AFM probe has an integrated tip made of a thick sputtered silicon layer, which is deposited after the probe has been defined and just before the cantilevers are released. The tips are so-called rocket tips made by reactive ion etching. We present probes...

  14. Sputtered thin films for high density tape recording

    NARCIS (Netherlands)

    Nguyen, L.T.

    This thesis describes the investigation of sputtered thin film media for high density tape recording. As discussed in Chapter 1, to meet the tremendous demand of data storage, the density of recording tape has to be increased continuously. For further increasing the bit density the key factors are:

  15. Basic electrochemical properties of sputtered gold film electrodes

    International Nuclear Information System (INIS)

    Libansky, Milan; Zima, Jiri; Barek, Jiri; Reznickova, Alena; Svorcik, Vaclav; Dejmkova, Hana

    2017-01-01

    Gold nanolayers made by sputtering of pure gold (physical vapour deposition) are commonly used for many biophysical and material applications. However, the use of sputtering method for fabrication of working electrodes for electroanalytical purposes is less common. This paper focuses on the testing and characterization of sputtered working roughened gold nanostructured film electrodes, which fall into category of upcoming desirable new generation of nanostructured gold working electrodes. Gold nanostructured films (80 nm thin) were sputtered onto 50 μm thin PTFE substrates with three different types of treatment: pristine, plasma treated, and plasma treated and subsequently spontaneously grafted with biphenyl-4,4′-dithiol. The characterization of gold nanostructured film electrodes was carried out by examination of the electrode reaction of standard redox probes (ferrocyanide/ferricyanide, hydroquinone/benzoquinone) in different types of supporting electrolytes (BR buffers of various pH, KCl, KNO 3 , H 2 SO 4 ), by exploration of the electrode surface by scanning electron microscopy, by atomic force microscopy accompanied by elementary analysis and contact angle measurements. The testing of electrodes was complemented by an attempt to calculate their real surface areas from Randles-Sevcik equation. All results were compared to conventional bulk gold electrode. The practical applicability of the nanostructured gold electrodes as sensors for the determination of environmental pollutants was verified by voltammetric determination of hydroquinone as a model electrochemically oxidisable organic environmental pollutant.

  16. Development of ion beam sputtering techniques for actinide target preparation

    Science.gov (United States)

    Aaron, W. S.; Zevenbergen, L. A.; Adair, H. L.

    1985-06-01

    Ion beam sputtering is a routine method for the preparation of thin films used as targets because it allows the use of a minimum quantity of starting material, and losses are much lower than most other vacuum deposition techniques. Work is underway in the Isotope Research Materials Laboratory (IRML) at ORNL to develop the techniques that will make the preparation of actinide targets up to 100 μg/cm 2 by ion beam sputtering a routinely available service from IRML. The preparation of the actinide material in a form suitable for sputtering is a key to this technique, as is designing a sputtering system that allows the flexibility required for custom-ordered target production. At present, development work is being conducted on low-activity actinides in a bench-top system. The system will then be installed in a hood or glove box approved for radioactive materials handling where processing of radium, actinium, and plutonium isotopes among others will be performed.

  17. RF Reactive Magnetron Sputter Deposition of Silicon Sub-Oxides

    NARCIS (Netherlands)

    Hattum, E.D. van

    2007-01-01

    RF reactive magnetron plasma sputter deposition of silicon sub oxide E.D. van Hattum Department of Physics and Astronomy, Faculty of Sciences, Utrecht University The work described in the thesis has been inspired and stimulated by the use of SiOx layers in the direct inductive printing technology,

  18. Preparation of boron-nitrogen films by sputtering

    International Nuclear Information System (INIS)

    Klose, S.; Winde, B.

    1980-01-01

    Hard boron-nitrogen films adherent to various substrates can be prepared by sputtering. IR investigations suggest the existence of cubic boron nitride in certain layers. Transmission electron microscope studies have shown a quasi-amorphous structure irregularly incorporating crystallites of zinc blende structure of some nm in diameter

  19. Doubly Charged Ion Emission in Sputtering of Monocrystalline Fluorides

    Czech Academy of Sciences Publication Activity Database

    Lörinčík, Jan; Šroubek, Zdeněk

    2002-01-01

    Roč. 187, - (2002), s. 447-450 ISSN 0168-583X R&D Projects: GA ČR GA202/99/0881; GA AV ČR IAA1067801 Institutional research plan: CEZ:AV0Z4040901 Keywords : secondary ion emission * doubly charged * sputtering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.158, year: 2002

  20. Oblique sputtered and evaporated magnetic thin films for tape recording

    NARCIS (Netherlands)

    Bijker, M.D.

    1998-01-01

    After having introduced some aspects of tape recording in chapter one, chapter two deals with the magnetron sputtering process itself. The kinetic energy of the electrons which are bound to the groove region by the combined action of the B and E field, was calculated. It was found that for a

  1. Inhomogeneous strain states in sputter deposited tungsten thin films

    International Nuclear Information System (INIS)

    Noyan, I.C.; Shaw, T.M.; Goldsmith, C.C.

    1997-01-01

    The results of an x-ray diffraction study of dc-magnetron sputtered tungsten thin films are reported. It is shown that the phase transformation from the β to α W can cause multilayered single-phase films where the layers have very different stress states even if the films are in the 500 nm thickness range. copyright 1997 American Institute of Physics

  2. Physicochemical model for reactive sputtering of hot target

    Energy Technology Data Exchange (ETDEWEB)

    Shapovalov, Viktor I., E-mail: vishapovalov@mail.ru; Karzin, Vitaliy V.; Bondarenko, Anastasia S.

    2017-02-05

    A physicochemical model for reactive magnetron sputtering of a metal target is described in this paper. The target temperature in the model is defined as a function of the ion current density. Synthesis of the coating occurs due to the surface chemical reaction. The law of mass action, the Langmuir isotherm and the Arrhenius equation for non-isothermal conditions were used for mathematical description of the reaction. The model takes into consideration thermal electron emission and evaporation of the target surface. The system of eight algebraic equations, describing the model, was solved for the tantalum target sputtered in the oxygen environment. It was established that the hysteresis effect disappears with the increase of the ion current density. - Highlights: • When model is applied for a cold target, hysteresis width is proportional to the ion current density. • Two types of processes of hot target sputtering are possible, depending on the current density: with and without the hysteresis. • Sputtering process is dominant at current densities less than 50 A/m{sup 2} and evaporation can be neglected. • For current densities over 50 A/m{sup 2} the hysteresis width reaches its maximum and the role of evaporation increases.

  3. Plasma properties of RF magnetron sputtering system using Zn target

    Energy Technology Data Exchange (ETDEWEB)

    Nafarizal, N.; Andreas Albert, A. R.; Sharifah Amirah, A. S.; Salwa, O.; Riyaz Ahmad, M. A. [Microelectronic and Nanotechnology - Shamsuddin Research Centre (MiNT-SRC), Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia 86400 Parit Raja, Batu Pahat, Johor (Malaysia)

    2012-06-29

    In the present work, we investigate the fundamental properties of magnetron sputtering plasma using Zn target and its deposited Zn thin film. The magnetron sputtering plasma was produced using radio frequency (RF) power supply and Argon (Ar) as ambient gas. A Langmuir probe was used to collect the current from the plasma and from the current intensity, we calculate the electron density and electron temperature. The properties of Zn sputtering plasma at various discharge conditions were studied. At the RF power ranging from 20 to 100 W and gas pressure 5 mTorr, we found that the electron temperature was almost unchanged between 2-2.5 eV. On the other hand, the electron temperature increased drastically from 6 Multiplication-Sign 10{sup 9} to 1 Multiplication-Sign 10{sup 10}cm{sup -3} when the discharge gas pressure increased from 5 to 10 mTorr. The electron microscope images show that the grain size of Zn thin film increase when the discharge power is increased. This may be due to the enhancement of plasma density and sputtered Zn density.

  4. Spatiotemporal synchronization of drift waves in a magnetron sputtering plasma

    Czech Academy of Sciences Publication Activity Database

    Martines, E.; Zuin, M.; Cavazzana, R.; Adámek, Jiří; Antoni, V.; Serianni, G.; Spolaore, M.; Vianello, N.

    2014-01-01

    Roč. 21, č. 10 (2014), s. 102309-102309 ISSN 1070-664X Institutional support: RVO:61389021 Keywords : Drift waves * Magnetron sputtering plasma * Spatiotemporal synchronization Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.142, year: 2014 http://dx.doi.org/10.1063/1.4898693

  5. Hard nanocrystalline Zr-B-C-N films with high electrical conductivity prepared by pulsed magnetron sputtering

    Czech Academy of Sciences Publication Activity Database

    Vlček, J.; Steidl, P.; Kohout, J.; Čerstvý, R.; Zeman, P.; Prokšová, S.; Peřina, Vratislav

    2013-01-01

    Roč. 215, JAN 25 (2013), s. 186-191 ISSN 0257-8972. [39th International Conference on Metallurgical Coatings and Thin Films (ICMTF). San Diego, California, 23.04.2012-27.04.2012] Institutional support: RVO:61389005 Keywords : Zr-B-C-N films * nanocomposite materials * pulsed magnetron sputtering * hard ness * high electrical conductivity * osidation resistance Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 2.199, year: 2013 http://www.sciencedirect.com/science/article/pii/S0257897212010584

  6. Investigation of ion sputtering for eutectic Cu-37 at% Ag alloys

    International Nuclear Information System (INIS)

    Wang Zhenxia; Pan Jisheng; Zhang Jiping; Tao Zhenlan; Zhu Fuying; Zhao Lie; Zhang Huiming

    1994-01-01

    Angular distributions of sputtered atoms and the phenomenon of element locally rich relative to micro-topographic feature (ELR-MTF) of sputtered target surface have been investigated for Cu-37 at% Ag alloys by means of RBS, SEM and EPMA measurements. In the paper,emphasis will be put on the correlation between surface topography caused by Ar + ion bombardment with different doses and angular distribution of sputtered atoms ejecting from various micro-zones at topographical surface during sputtering. The experiment result was explained with the so-called ELR-MTF model which can qualitatively interpret the shape of the angular distributions and the variation of the preferential sputtering curves

  7. Low-damage high-throughput grazing-angle sputter deposition on graphene

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.-T.; Gajek, M.; Raoux, S. [IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Casu, E. A. [IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Politecnico di Torino, Turin 10129 (Italy)

    2013-07-15

    Despite the prevalence of sputter deposition in the microelectronics industry, it has seen very limited applications for graphene electronics. In this letter, we report systematic investigation of the sputtering induced damages in graphene and identify the energetic sputtering gas neutrals as the primary cause of graphene disorder. We further demonstrate a grazing-incidence sputtering configuration that strongly suppresses fast neutral bombardment and retains graphene structure integrity, creating considerably lower damage than electron-beam evaporation. Such sputtering technique yields fully covered, smooth thin dielectric films, highlighting its potential for contact metals, gate oxides, and tunnel barriers fabrication in graphene device applications.

  8. Low-damage high-throughput grazing-angle sputter deposition on graphene

    International Nuclear Information System (INIS)

    Chen, C.-T.; Gajek, M.; Raoux, S.; Casu, E. A.

    2013-01-01

    Despite the prevalence of sputter deposition in the microelectronics industry, it has seen very limited applications for graphene electronics. In this letter, we report systematic investigation of the sputtering induced damages in graphene and identify the energetic sputtering gas neutrals as the primary cause of graphene disorder. We further demonstrate a grazing-incidence sputtering configuration that strongly suppresses fast neutral bombardment and retains graphene structure integrity, creating considerably lower damage than electron-beam evaporation. Such sputtering technique yields fully covered, smooth thin dielectric films, highlighting its potential for contact metals, gate oxides, and tunnel barriers fabrication in graphene device applications

  9. Low-damage high-throughput grazing-angle sputter deposition on graphene

    Science.gov (United States)

    Chen, C.-T.; Casu, E. A.; Gajek, M.; Raoux, S.

    2013-07-01

    Despite the prevalence of sputter deposition in the microelectronics industry, it has seen very limited applications for graphene electronics. In this letter, we report systematic investigation of the sputtering induced damages in graphene and identify the energetic sputtering gas neutrals as the primary cause of graphene disorder. We further demonstrate a grazing-incidence sputtering configuration that strongly suppresses fast neutral bombardment and retains graphene structure integrity, creating considerably lower damage than electron-beam evaporation. Such sputtering technique yields fully covered, smooth thin dielectric films, highlighting its potential for contact metals, gate oxides, and tunnel barriers fabrication in graphene device applications.

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

    Czech Academy of Sciences Publication Activity Database

    Souček, P.; Schmidtová, T.; Bursíková, V.; Vašina, P.; Pei, Y.; De Hos, J. Th. M.; Caha, O.; Peřina, Vratislav; Mikšová, Romana; Malinský, Petr

    2014-01-01

    Roč. 241, FEB (2014), s. 64-73 ISSN 0257-8972 R&D Projects: GA MŠk(XE) LM2011019; GA ČR(CZ) GD104/09/H080 Institutional support: RVO:61389005 Keywords : nanocomposites * magnetron sputtering * Titanium carbide * ion flux * friction * wear Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.998, year: 2014

  11. Magnetron sputtered Hf-B-Si-C-N films with controlled electrical conductivity and optical transparency, and with ultrahigh oxidation resistance

    Czech Academy of Sciences Publication Activity Database

    Šímová, V.; Vlček, J.; Zuzjaková, Š.; Houška, J.; Shen, Y.; Jiang, J. C.; Meletis, E. I.; Peřina, Vratislav

    2018-01-01

    Roč. 653, č. 5 (2018), s. 333-340 ISSN 0040-6090 R&D Projects: GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : Hf-B-Si-C-N films * pulsed reactive magnetron sputtering * electrical conductivitiy * optical transparency * high-temperature oxidation resistance Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 1.879, year: 2016

  12. Anion binding by biotin[6]uril in water

    DEFF Research Database (Denmark)

    Lisbjerg, Micke; Nielsen, Bjarne Enrico; Milhøj, Birgitte Olai

    2015-01-01

    In this contribution we show that the newly discovered 6 + 6 biotin-formaldehyde macrocycle Biotin[6]uril binds a variety of anionic guest molecules in water. We discuss how and why the anions are bound based on data obtained using NMR spectroscopy, mass spectrometry, isothermal titration...

  13. A colorimetric tetrathiafulvalene-calix 4 pyrrole anion sensor

    DEFF Research Database (Denmark)

    Nielsen, K. A.

    2012-01-01

    The interaction and colorimetric sensing properties of a tetrathiafulvalene substituted calix[4]pyrrole sensor with anions were investigated using H-1 NMR and absorption spectroscopic techniques. Visual color changes were observed upon addition of different anions (Cl-, Br-, CN-, and Ac......O-) to a solution of the sensor. (C) 2012 Elsevier Ltd. All rights reserved....

  14. Diffuse neutron scattering from anion-excess strontium chloride

    DEFF Research Database (Denmark)

    Goff, J.P.; Clausen, K.N.; Fåk, B.

    1992-01-01

    The defect structure and diffusional processes have been studied in the anion-excess fluorite (Sr, Y)Cl2.03 by diffuse neutron scattering techniques. Static cuboctahedral clusters found at ambient temperature break up at temperatures below 1050 K, where the anion disorder is highly dynamic. The a...

  15. Protonation Reaction of Benzonitrile Radical Anion and Absorption of Product

    DEFF Research Database (Denmark)

    Holcman, Jerzy; Sehested, Knud

    1975-01-01

    The rate constant for the protonation of benzonitrile radical anions formed in pulse radiolysis of aqueous benzonitrile solutions is (3.5 ± 0.5)× 1010 dm3 mol–1 s–1. A new 270 nm absorption band is attributed to the protonated benzonitrile anion. The pK of the protonation reaction is determined t...

  16. Comparative study of the characteristics of Ni films deposited on SiO2/Si(100) by oblique-angle sputtering and conventional sputtering

    International Nuclear Information System (INIS)

    Yu Mingpeng; Qiu Hong; Chen Xiaobai; Wu Ping; Tian Yue

    2008-01-01

    Ni films were deposited on SiO 2 /Si(100) substrates at 300 K and 573 K by oblique-angle sputtering and conventional sputtering. The films deposited at 300 K mainly have a [110] crystalline orientation in the growing direction whereas those deposited at 573 K grow with a [111] crystalline orientation in the growing direction. The film prepared only at 300 K by oblique-angle sputtering grows with a weakly preferential orientation along the incidence direction of the sputtered Ni atoms. All the films grow with thin columnar grains perpendicular to the substrate surface. The grain size of the films sputter-deposited obliquely is larger than that of the films sputter-deposited conventionally. The grain size of the Ni film does not change markedly with the deposition temperature. The film deposited at 573 K by oblique-angle sputtering has the highest saturation magnetization. For the conventional sputtering, the coercivity of the Ni film deposited at 573 K is larger than that of the film deposited at 300 K. However, for the oblique-angle sputtering, the coercivity of the Ni film is independent of the deposition temperature. All the Ni films exhibit an isotropic magnetization characteristic in the film plane

  17. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    International Nuclear Information System (INIS)

    Moyer, Bruce a.; Bostick, Debra A.; Fowler, Christopher J.; Kang, Hyun-Ah; Ruas, Alexandre; Delmau, Laetitia H.; Haverlock, Tamara J.; Llinares, Jose M.; Hossain, Alamgir; Kang, S. O.; Bowman-James, Kristin; Shriver, James A.; Marquez, Manuel; Sessler, Jonathan L.

    2005-01-01

    The major thrust of this project led by the University of Kansas (Prof. Kristin Bowman-Jones) entails the exploration of the principles of recognition and separation of sulfate by the design, synthesis, and testing of novel sulfate extractants. A key science need for the cleanup of tank wastes at Hanford has been identified in developing methods to separate those bulk waste components that have low solubilities in borosilicate glass. Sulfate has been identified as a particularly difficult and expensive problem in that its concentration in the waste is relatively high, its solubility in glass is especially low, and it interferes with the performance of both vitrification equipment and the glass waste form. The new extractants will be synthesized by the University of Kansas and the University of Texas, Austin. Oak Ridge National Laboratory (ORNL) is subjecting the new extractants to experiments that will determine their properties and effectiveness in separating sulfate from the major competing anions in the waste, especially nitrate. Such experiments will entail primarily liquid-liquid extraction. Current efforts focus on exciting new systems in which the anion receptors act as synergists for anion exchange

  18. AT Base Pair Anions vs. (9-methyl-A)(1-methyl-T) Base Pair Anions

    International Nuclear Information System (INIS)

    Radisic, Dunja; Bowen, Kit H.; Dabkowska, Iwona; Storoniak, Piotr; Rak, Janusz; Gutowski, Maciej S.

    2005-01-01

    The anionic base pairs of adenine and thymine, (AT)-, and 9-methyladenine and 1-methylthymine, (MAMT)-, have been investigated both theoretically and experimentally in a complementary, synergistic study. Calculations on (AT)- found that it had undergone a barrier-free proton transfer (BFPT) similar to that seen in other dimer anion systems and that its structural configuration that was neither Watson-Crick (WC) nor Hoogsteen (HS). The vertical detachment energy (VDE) of (AT)- was determined by anion photoelectron spectroscopy and found to be in agreement with the VDE value predicted by theory for the BFPT mechanism. An AT pair in DNA is structurally immobilized into the WC configuration, in part, by being bonded to the sugars of the double helix. This circumstance was mimicked by methylating the sites on both A and T where these sugars would have been tied, viz., 9-methyladenine and 1-methylthymine. Calculations found no BFPT in (MAMT)- and a resulting (MAMT)- configuration that wa s either HS or WC, with the configurations differing in stability by ca. 2 kcal/mol. The photoelectron spectrum of (MAMT)- occurred at a completely different electron binding energy than had (AT)-. Moreover, the VDE value of (MAMT)- was in agreement with that predicted by theory. The configuration of (MAMT)- and its lack of electron-induced proton transfer are inter-related. While there may be other pathways for electron-induced damage, BFPT in the WC/HS configurations of (AT)- is not feasible

  19. AT base pair anions versus (9-methyl-A)(1-methyl-T) base pair anions.

    Science.gov (United States)

    Radisic, Dunja; Bowen, Kit H; Dabkowska, Iwona; Storoniak, Piotr; Rak, Janusz; Gutowski, Maciej

    2005-05-04

    The anionic base pairs of adenine and thymine, (AT)(-), and 9-methyladenine and 1-methylthymine, (MAMT)(-), have been investigated both theoretically and experimentally in a complementary, synergistic study. Calculations on (AT)(-) found that it had undergone a barrier-free proton transfer (BFPT) similar to that seen in other dimer anion systems and that its structural configuration was neither Watson-Crick (WC) nor Hoogsteen (HS). The vertical detachment energy (VDE) of (AT)(-) was determined by anion photoelectron spectroscopy and found to be in agreement with the VDE value predicted by theory for the BFPT mechanism. An AT pair in DNA is structurally immobilized into the WC configuration, in part, by being bonded to the sugars of the double helix. This circumstance was mimicked by methylating the sites on both A and T where these sugars would have been tied, viz., 9-methyladenine and 1-methylthymine. Calculations found no BFPT in (MAMT)(-) and a resulting (MAMT)(-) configuration that was either HS or WC, with the configurations differing in stability by ca. 2 kcal/mol. The photoelectron spectrum of (MAMT)(-) occurred at a completely different electron binding energy than had (AT)(-). Moreover, the VDE value of (MAMT)(-) was in agreement with that predicted by theory. The configuration of (MAMT)(-) and its lack of electron-induced proton transfer are inter-related. While there may be other pathways for electron-induced DNA alterations, BFPT in the WC/HS configurations of (AT)(-) is not feasible.

  20. Study of the ion sputter-machining, 1

    International Nuclear Information System (INIS)

    Miyamoto, Iwao; Taniguchi, Norio

    1979-01-01

    A lattice disordering of the surface of single crystal silicon due to ion bombardment of Ar + was investigated by the high energy electron diffraction method, with the incident angle of 1.7 0 and 2.8 0 . By this measuring system, the degree of disorders of the sputter-machined surface layer of Si single crystal in the depth of 50 A and 30 A has been determined, under the working conditions of the ion energy ranging from 0.2 keV to 1.5 keV and the incident angle of ion ranging from 0 0 to 75 0 . Moreover, the recovery of lattice disorder of sputter-machined surface layer of Si single crystal by means of the isochronal thermal annealing has been also confirmed by the same method. From the above experiments, the following conclusions are obtained. (1) The layers of sputter-machined surface of Si single crystal workpiece are highly disordered like amorphous, under the working conditions of ion energy ranging from 0.2 keV to 1.5 keV for the vertical ion incident angle. (2) Under the working conditions of ion incident angle larger than 60 0 , using the ion beam with a lower energy under 300 eV, the surface of the workpiece is not disordered. Therefore, a sputter-machined surface of Si single crystal with highly ordered structure can be obtained under this working condition. (3) The recovery of disorder of sputter-machined surface is completed by the heat-treatment of workpiece under isochronal annealing for 1 hour at 800 0 C. However, it is not clear whether this recovery of lattice point or the dispersion of interstitially located argon atoms from the surface to the outside. (author)

  1. Superoxide anion production by human neutrophils activated by Trichomonas vaginalis.

    Science.gov (United States)

    Song, Hyun-Ouk; Ryu, Jae-Sook

    2013-08-01

    Neutrophils are the predominant inflammatory cells found in vaginal discharges of patients infected with Trichomonas vaginalis. In this study, we examined superoxide anion (O2 (.-)) production by neutrophils activated by T. vaginalis. Human neutrophils produced superoxide anions when stimulated with either a lysate of T. vaginalis, its membrane component (MC), or excretory-secretory product (ESP). To assess the role of trichomonad protease in production of superoxide anions by neutrophils, T. vaginalis lysate, ESP, and MC were each pretreated with a protease inhibitor cocktail before incubation with neutrophils. Superoxide anion production was significantly decreased by this treatment. Trichomonad growth was inhibited by preincubation with supernatants of neutrophils incubated for 3 hr with T. vaginalis lysate. Furthermore, myeloperoxidase (MPO) production by neutrophils was stimulated by live trichomonads. These results indicate that the production of superoxide anions and MPO by neutrophils stimulated with T. vaginalis may be a part of defense mechanisms of neutrophils in trichomoniasis.

  2. Coumarin amide derivatives as fluorescence chemosensors for cyanide anions

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qianqian [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China); Liu, Zhiqiang [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, Shandong (China); Cao, Duxia, E-mail: duxiacao@ujn.edu.cn [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China); Guan, Ruifang, E-mail: mse_guanrf@ujn.edu.cn [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China); Wang, Kangnan; Shan, Yanyan; Xu, Yongxiao; Ma, Lin [School of Material Science and Engineering, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, Shandong (China)

    2015-07-01

    Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group have been synthesized. Their photophysical properties and recognition properties for cyanide anions have been examined. The results indicate that the compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change, at the same time, obvious color and fluorescence change can be observed by naked eye. The in situ hydrogen nuclear magnetic resonance spectra and photophysical properties change confirm that Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin. - Highlights: • Four coumarin amide derivatives with 4-methyl coumarin or pyrene as terminal group were synthesized. • The compounds can recognize cyanide anions with obvious absorption and fluorescence spectra change. • Michael additions between the chemosensors and cyanide anions take place at the 4-position of coumarin.

  3. The Thermodynamics of Anion Complexation to Nonpolar Pockets.

    Science.gov (United States)

    Sullivan, Matthew R; Yao, Wei; Tang, Du; Ashbaugh, Henry S; Gibb, Bruce C

    2018-02-08

    The interactions between nonpolar surfaces and polarizable anions lie in a gray area between the hydrophobic and Hofmeister effects. To assess the affinity of these interactions, NMR and ITC were used to probe the thermodynamics of eight anions binding to four different hosts whose pockets each consist primarily of hydrocarbon. Two classes of host were examined: cavitands and cyclodextrins. For all hosts, anion affinity was found to follow the Hofmeister series, with associations ranging from 1.6-5.7 kcal mol -1 . Despite the fact that cavitand hosts 1 and 2 possess intrinsic negative electrostatic fields, it was determined that these more enveloping hosts generally bound anions more strongly. The observation that the four hosts each possess specific anion affinities that cannot be readily explained by their structures, points to the importance of counter cations and the solvation of the "empty" hosts, free guests, and host-guest complexes, in defining the affinity.

  4. Laboratory Anion Chemistry: Implications for the DIBs, and a Potential Formation Mechanism for a Known Interstellar Molecule

    Science.gov (United States)

    Eichelberger, B.; Barckholtz, C.; Stepanovic, M.; Bierbaum, V.; Snow, T.

    2002-01-01

    Due to recent interest in molecular anions as possible interstellar species, we have carried out several laboratory studies of anion chemistry. The reactions of the series C(sub n)(sup -); and C(sub n)H(sup -) with H and H2 were studied to address the viability of such species in the diffuse interstellar medium and to address their ability to be carriers of the diffuse interstellar bands (DIBs). These same molecules were also reacted with N and O to show possible heteroatomic products. C(sub m)N(sup - was a particularly stable product from the reaction of C(sub n)(sup -) + N. C3N(sup -) was further reacted with H to study chemistry that could produce HC3N, a known interstellar species. The reactions were done in a flowing afterglow selected ion flow tube apparatus (FA-SIFT). The anions were generated in an electron impact or cold cathode discharge source and the anion of interest was then selected by a quadrupole mass filter. The selected ion was then reacted with the atomic or molecular species in the flow tube and products were detected by another quadrupole. While the C(sub n)(sup -) species do not appear to be viable DIB carriers, their possible presence could provide a mechanism for the formation of known heteroatomic neutral molecules detected in the interstellar medium (ISM).

  5. Depth of origin of sputtered atoms: Experimental and theoretical study of Cu/Ru(0001)

    International Nuclear Information System (INIS)

    Burnett, J.W.; Biersack, J.P.; Gruen, D.M.; Joergensen, B.; Krauss, A.R.; Pellin, M.J.; Schweitzer, E.L.; Yates, J.T. Jr.; Young, C.E.

    1987-01-01

    The depth of origin of sputtered atoms is a subject of considerable interest. The surface sensitivity of analytical techniques such as Secondary Ion Mass Spectrometry (SIMS) and Surface Analysis by Resonance Ionization of Sputtered Atoms (SARISA), and the sputtering properties of strongly segregating alloy systems, are critically dependent on the sputtering depth of origin. A significant discrepancy exists between the predictions of the Sigmund theory and computer sputtering models; in general, the computer models predict a much shallower depth of origin. The existing experimental evidence suggests that most of the sputtered atoms originate in the topmost atomic layer, but until recently, the results have not been definitive. We have experimentally determined the depth of origin of atoms sputtered from surfaces consisting of Cu films of less than two monolayers on a Ru(0001) substrate. The Cu/Ru target was statically sputtered using 3.6 keV Ar + . The sputtered neutrals were non-resonantly laser ionized and detected using SARISA. The Cu/Ru sputtering yield ratio and the suppression of the Ru sputtering yield were determined for various Cu coverages. The results indicate that the majority of the sputtered atoms originate in the topmost atomic layer. The Cu/Ru system is also modeled using a modified Transport of Ions in Matter (TRIM) code. It was found that TRIM C does not correctly treat the first atomic layer, resulting in a serious underestimate of the number of sputtered atoms which originate in this layer. The corrected version adequately describes the results, predicting that for the experimental conditions roughly two-thirds of the sputtered atoms originate in the first atomic layer. These results are significantly greater than the Sigmund theory estimate of >40%. 26 refs., 3 figs., 1 tab

  6. Contributions of solar-wind induced potential sputtering to the lunar surface erosion rate and it's exosphere

    Science.gov (United States)

    Alnussirat, S. T.; Barghouty, A. F.; Edmunson, J. E.; Sabra, M. S.; Rickman, D. L.

    2018-04-01

    Sputtering of lunar regolith by solar-wind protons and heavy ions with kinetic energies of about 1 keV/amu is an important erosive process that affects the lunar surface and exosphere. It plays an important role in changing the chemical composition and thickness of the surface layer, and in introducing material into the exosphere. Kinetic sputtering is well modeled and understood, but understanding of mechanisms of potential sputtering has lagged behind. In this study we differentiate the contributions of potential sputtering from the standard (kinetic) sputtering in changing the chemical composition and erosion rate of the lunar surface. Also we study the contribution of potential sputtering in developing the lunar exosphere. Our results show that potential sputtering enhances the total characteristic sputtering erosion rate by about 44%, and reduces sputtering time scales by the same amount. Potential sputtering also introduces more material into the lunar exosphere.

  7. Binding of anions in triply interlocked coordination catenanes and dynamic allostery for dehalogenation reactions.

    Science.gov (United States)

    Yang, Linlin; Jing, Xu; An, Bowen; He, Cheng; Yang, Yang; Duan, Chunying

    2018-01-28

    By synergistic combination of multicomponent self-assembly and template-directed approaches, triply interlocked metal organic catenanes that consist of two isolated chirally identical tetrahedrons were constructed and stabilized as thermodynamic minima. In the presence of suitable template anions, the structural conversion from the isolated tetrahedral conformers into locked catenanes occurred via the cleavage of an intrinsically reversible coordination bond in each of the tetrahedrons, followed by the reengineering and interlocking of two fragments with the regeneration of the broken coordination bonds. The presence of several kinds of individual pocket that were attributed to the triply interlocked patterns enabled the possibility of encapsulating different anions, allowing the dynamic allostery between the unlocked/locked conformers to promote the dehalogenation reaction of 3-bromo-cyclohexene efficiently, as with the use of dehalogenase enzymes. The interlocked structures could be unlocked into two individual tetrahedrons through removal of the well-matched anion templates. The stability and reversibility of the locked/unlocked structures were further confirmed by the catching/releasing process that accompanied emission switching, providing opportunities for the system to be a dynamic molecular logic system.

  8. Antibodies to the CFTR modulate the turgor pressure of guard cell protoplasts via slow anion channels.

    Science.gov (United States)

    Leonhardt, N; Bazin, I; Richaud, P; Marin, E; Vavasseur, A; Forestier, C

    2001-04-06

    The plasma membrane guard cell slow anion channel is a key element at the basis of water loss control in plants allowing prolonged osmolite efflux necessary for stomatal closure. This channel has been extensively studied by electrophysiological approaches but its molecular identification is still lacking. Recently, we described that this channel was sharing some similarities with the mammalian ATP-binding cassette protein, cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel [Leonhardt, N. et al. (1999) Plant Cell 11, 1141-1151]. Here, using the patch-clamp technique and a bioassay, consisting in the observation of the change in guard cell protoplasts volume, we demonstrated that a functional antibody raised against the mammalian CFTR prevented ABA-induced guard cell protoplasts shrinking and partially inhibited the slow anion current. Moreover, this antibody immunoprecipitated a polypeptide from guard cell protein extracts and immunolabeled stomata in Vicia faba leaf sections. These results indicate that the guard cell slow anion channel is, or is closely controlled by a polypeptide, exhibiting one epitope shared with the mammalian CFTR.

  9. Kinetic and Potential Sputtering of Lunar Regolith: The Contribution of the Heavy Highly Charged (Minority) Solar Wind Ions

    Science.gov (United States)

    Meyer, F. W.; Barghouty, A. F.

    2012-01-01

    Solar wind sputtering of the lunar surface helps determine the composition of the lunar exosphere and contributes to surface weathering. To date, only the effects of the two dominant solar wind constituents, H+ and He+, have been considered. The heavier, less abundant solar wind constituents have much larger sputtering yields because they have greater mass (kinetic sputtering) and they are highly charged (potential sputtering) Their contribution to total sputtering can therefore be orders of magnitude larger than their relative abundances would suggest

  10. THE POSSIBLE INTERSTELLAR ANION CH2CN–: SPECTROSCOPIC CONSTANTS, VIBRATIONAL FREQUENCIES, AND OTHER CONSIDERATIONS

    International Nuclear Information System (INIS)

    Fortenberry, Ryan C.; Lee, Timothy J.; Crawford, T. Daniel

    2013-01-01

    The A 1 B 1 ⇽ X-tilde 1 A' excitation into the dipole-bound state of the cyanomethyl anion (CH 2 CN – ) has been hypothesized as the carrier for one diffuse interstellar band. However, this particular molecular system has not been detected in the interstellar medium even though the related cyanomethyl radical and the isoelectronic ketenimine molecule have been found. In this study, we are employing the use of proven quartic force fields and second-order vibrational perturbation theory to compute accurate spectroscopic constants and fundamental vibrational frequencies for X-tilde 1 A' CH 2 CN – in order to assist in laboratory studies and astronomical observations.

  11. Polarographic investigation of complexing kinetics of polyacrylate anions with cadmium ions

    International Nuclear Information System (INIS)

    Avlyanov, Zh.K.; Kabanov, N.M.; Zezin, A.B.; Askarov, M.A.

    1990-01-01

    The processes which occur during the reduction of cadmium ions from polymer-metallic complexes (PMC) are studied for the purposes of polarographic investigation of complexing kinetics of polyacrylate anions (PAA) of different molecular masses with cadmium ions in KCl aqueous solutions. An expression is derived for establishing semiwave potential. PMC formation and dissociation reduction rate constants are calculated. It is shown that intramolecular reorderings required for the formation of a two-coordinate complex proceed much slower as compared to the diffusion of free ions

  12. Radiative capture reactions and spectroscopy of multipolar anions in the framework of Gamow Shell Model

    International Nuclear Information System (INIS)

    Fossez, Kevin

    2014-01-01

    Small open quantum systems, whose properties are profoundly affected by the environment of continuum states, are intensely studied in various fields of Physics: nuclear physics, atomic and molecular physics, quantum optics, etc. These different many-body systems, in spite of their specific features, have generic properties which are common to all weakly bound or unbound systems close to the threshold. Coupling to the continuum is essential to describe the low-energy nuclear reactions of astrophysical interest, the formation of halo states in nuclei, atomic clusters and dipolar anions, or the near-threshold two neutron and alpha particle correlations (clustering). Recently, the open quantum system extension of the nuclear shell model, the Gamow shell model (GSM), based on the Berggren ensemble, has been applied successfully for the description of resonant states spectra in atomic nuclei. The coupled-channel formulation of the GSM (GSM-CC) allows to describe various low-energy nuclear reactions. In this work, the GSM-CC is formulated and applied for the description of proton/neutron radiative capture reactions of astrophysical interest, such as: 17 F(p, γ) 18 Ne, 7 Be(p, γ) 8 B and 7 Li(n, γ) 8 Li. Moreover, for the first time, the GSM has been applied in atomic physics for the description of spectra of dipolar anions. Systematic investigation of the hydrogen cyanide dipolar anion (HCN - ) allowed to identify the collective bands of states both in the strong coupling regime, for weakly bound halo states, and in the weak coupling regime above the dissociation threshold. In the strong coupling regime, K J = 0 anion a rotational band has been found. Above the threshold, K J quantum number is not conserved. Resonances in this regime form rotational bands according to the angular momentum of the rotating molecule, whereas the band head energies and the lifetimes depend predominantly on the external electron wave function. (author) [fr

  13. A novel anion exchange membrane from polystyrene (ethylene butylene) polystyrene: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Vinodh, Rajangam; Ilakkiya, Arjunan; Elamathi, Swaminathan [Department of Chemistry, Anna University Chennai, Sardar Patel Road, Chennai 600025, Tamil Nadu (India); Sangeetha, Dharmalingam, E-mail: sangeetha@annauniv.ed [Department of Chemistry, Anna University Chennai, Sardar Patel Road, Chennai 600025, Tamil Nadu (India)

    2010-02-25

    We look forward for an eco-friendly hydrocarbon polymer with higher molecular weight for the preparation of an anion exchange membrane. Polystyrene ethylene butylene polystyrene (PSEBS) was chosen as the polymer matrix. The anion exchange membrane was prepared from PSEBS tri-block co-polymer and then the properties were characterized for alkaline fuel cell application. The preparation of anion exchange polymer involved two steps namely chloromethylation and quaternization. The anion exchange membrane with high conductivity has been prepared by introducing quaternary ammonium groups in to the polymer. Finally, the membrane was prepared using solution casting method. The solution casting method yields highly hydrophilic membranes with uniform structure that were suitable for electrochemical applications. The efficiency of the entrapment was monitored by swelling ratio, chemical stability and ion exchange measurement. The characteristic structural properties of the membrane were investigated by FT-IR spectroscopy and {sup 1}H NMR spectroscopy. The thermal stability of the membrane was characterized by TGA, DSC and DMA (dynamic mechanical analysis). The prepared uniform electrolyte membrane in this study has high thermal and chemical stability. The surface morphology and elemental composition of the quaternized PSEBS was determined by SEM-EDXA techniques, respectively. The measured hydroxyl ion conductivity of the synthesized alkaline PSEBS polymer electrolyte membrane showed ionic conductivity in the range of 10{sup -3} S/cm in deionized water at room temperature. It was found that the substitution provided a flexible, chemically and thermally stable membrane. Hence, the membrane will have potential application in the alkaline fuel cell.

  14. Double Properties of Novel Acylhydrazone Nanomaterials Based on a Conjugated System: Anion Binding Ability and Antibacterial Activity

    Directory of Open Access Journals (Sweden)

    Xuefang Shang

    2015-10-01

    Full Text Available A series of new compounds (1–12 containing 1,5-diaza-fluorenone, 1,10-phenanthroline-5,6-dione, ferrocene-1,1ʹ-dione, anthracene-9-carbaldehyde have been synthesized and optimized. The nanomaterials were also developed successfully. The binding properties were evaluated for biologically important anions (F−, Cl−, Br−, I−, AcO−, and H2PO4− by theoretical investigation, UV-vis, and fluorescence experiments, and compound 6 displayed the strongest binding ability for AcO− ion among the synthesized compounds. Theoretical investigation analysis revealed that the intramolecular hydrogen bond existed in the structure of compound 6 and the roles of molecular frontier orbitals in molecular interplay. In addition, compound 6 showed wide antibacterial activity for colon bacillus, typhoid bacillus, and Pseudomonas aeruginosa, and inferior activity for hay bacillus and Staphylococcus aureus. This series of acylhydrazone nanomaterials showed double properties, anion binding ability, and antibacterial activity.

  15. Systematic study of the thermophysical properties of imidazolium-based ionic liquids with cyano-functionalized anions.

    Science.gov (United States)

    Neves, Catarina M S S; Kurnia, Kiki Adi; Coutinho, João A P; Marrucho, Isabel M; Lopes, José N Canongia; Freire, Mara G; Rebelo, Luís Paulo N

    2013-09-05

    In the past few years, ionic liquids (ILs) with cyano-functionalized anions have shown to be improved candidates for electrochemical and separation applications. Nevertheless, only scattered data exist hitherto and a broad analysis of their structure-property relationship has yet to be attempted. Therefore, in this work, a systematic study of the densities, viscosities and refractive indices of imidazolium-based ILs with cyano-functionalized anions was carried out at 0.1 MPa within a broad temperature range (from 278 to 363 K). The ILs under study are based on 1-alkyl-3-methylimidazolium cations (alkyl = ethyl, butyl and hexyl) combined with the [SCN](-), [N(CN)2](-), [C(CN)3](-) and [B(CN)4](-) anions. The selected matrix of cation/anion combinations allows us to provide a detailed and comprehensive investigation of the influence of the -CN group through an analysis of the thermophysical properties of the related ILs. The results show that, regardless of the cation, the densities decrease with an increase in the number of cyano groups or anion molecular weight. Moreover, for a fixed cation and temperature, the refractive index of the ILs decreases according to the rank: [SCN](-) > [N(CN)2](-) ≈ [C(CN)3](-) > [B(CN)4](-). On the other hand, no clear trend was observed for the viscosity of ILs and the respective number of -CN groups. The viscosity dependence on the cyano-functionalized anions decreases in the order: [SCN](-) > [B(CN)4](-) > [N(CN)2](-) > [C(CN)3](-). The isobaric thermal expansion coefficient, the derived molar refraction, the free volume, and the viscosity energy barrier of all compounds were estimated from the experimental data and are presented and discussed. Finally, group contribution models were applied, and new group contribution parameters are presented, extending these methods to the prediction of the ILs properties.

  16. Simultaneous determination of inorganic and organic anions by ion chromatography

    International Nuclear Information System (INIS)

    Park, Yang Soon; Joe, Ki Soo; Han, Sun Ho; Park, Soon Dal; Choi, Kwang Soon

    1999-06-01

    Four methods were investigated for the simultaneous determination of several inorganic and organic anions in aqueous solution by ion chromatography. The first is two columns coupled system. The second is the gradient elution system with an anion exchange column. The third is the system with a mixed-mode stationary phase. The fourth is the system with an anion exchange column and the eluant of low conductivity without ion suppressor. The advantages and disadvantages of individual systems were discussed. The suitable methods were proposed for the application to the samples of the nuclear power industry and the environment. (author)

  17. Unusual structures of MgF5- superhalogen anion

    Science.gov (United States)

    Anusiewicz, Iwona; Skurski, Piotr

    2007-05-01

    The vertical electron detachment energies (VDE) of three MgF5- anions were calculated at the outer valence Green function level with the 6-311 + G(3df) basis sets. This species was found to form unusual geometrical structures each of which corresponds to an anionic state exhibiting superhalogen nature. The global minimum structure was described as a system in which two central magnesium atoms are linked via symmetrical triangle formed by three fluorine atoms. Extremely large electron binding energies of these anions (exceeding 8.5 eV in all cases) were predicted and discussed.

  18. Adsorption properties of thermally sputtered calcein film

    Science.gov (United States)

    Kruglenko, I.; Burlachenko, J.; Kravchenko, S.; Savchenko, A.; Slabkovska, M.; Shirshov, Yu.

    2014-05-01

    High humidity environments are often found in such areas as biotechnology, food chemistry, plant physiology etc. The controlling of parameters of such ambiences is vitally important. Thermally deposited calcein films have extremely high adsorptivity at exposure to water vapor of high concentration. This feature makes calcein a promising material for humidity sensing applications. The aim of this work is to explain high sensitivity and selectivity of calcein film to high humidity. Quartz crystal microbalance sensor, AFM and ellipsometry were used for calcein film characterization and adsorption properties investigation. The proposed model takes into account both the molecular properties of calcein (the presence of several functional groups capable of forming hydrogen bonds, and their arrangement) and the features of structure of thermally deposited calcein film (film restructuring due to the switching of bonds "calcein-calcein" to "calcein-water" in the course of water adsorption).

  19. Ion beam sputtering of Ti: Influence of process parameters on angular and energy distribution of sputtered and backscattered particles

    Energy Technology Data Exchange (ETDEWEB)

    Lautenschläger, T. [Leibniz-Institute of Surface Modification, 04318 Leipzig (Germany); Feder, R., E-mail: thomas.lautenschlaeger@iom-leipzig.de [Leibniz-Institute of Surface Modification, 04318 Leipzig (Germany); Neumann, H. [Leibniz-Institute of Surface Modification, 04318 Leipzig (Germany); Rice, C.; Schubert, M. [Department of Electrical and Computer Engineering and Center for Nanohybrid Functional Materials, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511 (United States); Bundesmann, C. [Leibniz-Institute of Surface Modification, 04318 Leipzig (Germany)

    2016-10-15

    Highlights: • Ion beam sputter deposition under systematic variation of process parameters. • Angular and energy distribution of secondary particles. • Interaction between incorporated and impinging process gas. • Measured data compared with simulations. - Abstract: In the present study, the influence of ion energy and geometrical parameters onto the angular and energy distribution of secondary particles for sputtering a Ti target with Ar ions is investigated. The angular distribution of the particle flux of the sputtered Ti atoms was determined by the collection method, i.e. by growing Ti films and measuring their thickness. The formal description of the particle flux can be realized by dividing it into an isotropic and an anisotropic part. The experimental data show that increasing the ion energy or decreasing the ion incidence angle lead to an increase of the isotropic part, which is in good agreement with basic sputtering theory. The energy distribution of the secondary ions was measured using an energy-selective mass spectrometer. The energy distribution of the sputtered target ions shows a maximum at an energy between 10 eV and 20 eV followed by a decay proportional to E{sup −n}, which is in principle in accordance with Thompson’s theory, followed by a high energetic tail. When the sum of incidence angle and emission angle is increased, the high-energetic tail expands to higher energies and an additional peak due to direct sputtering events may occur. In the case of backscattered primary Ar ions, a maximum at an energy between 5 eV and 10 eV appears and, depending on the scattering geometry, an additional broad peak at a higher energy due to direct scattering events is observed. The center energy of the additional structure shifts systematically to higher energies with decreasing scattering angle or increasing ion energy. The experimental results are compared to calculations based on simple elastic two-particle-interaction theory and to

  20. Deuterium sputtering of Li and Li-O films

    Science.gov (United States)

    Nelson, Andrew; Buzi, Luxherta; Kaita, Robert; Koel, Bruce

    2017-10-01

    Lithium wall coatings have been shown to enhance the operational plasma performance of many fusion devices, including NSTX and other tokamaks, by reducing the global wall recycling coefficient. However, pure lithium surfaces are extremely difficult to maintain in experimental fusion devices due to both inevitable oxidation and codeposition from sputtering of hot plasma facing components. Sputtering of thin lithium and lithium oxide films on a molybdenum target by energetic deuterium ion bombardment was studied in laboratory experiments conducted in a surface science apparatus. A Colutron ion source was used to produce a monoenergetic, mass-selected ion beam. Measurements were made under ultrahigh vacuum conditions as a function of surface temperature (90-520 K) using x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and temperature programmed desorption (TPD). Results are compared with computer simulations conducted on a temperature-dependent data-calibrated (TRIM) model.

  1. Sputter deposition of BSCCO films from a hollow cathode

    International Nuclear Information System (INIS)

    Lanagan, M.T.; Kampwirth, R.T.; Doyle, K.; Kowalski, S.; Miller, D.; Gray, K.E.

    1991-01-01

    High-T c superconducting thin films were deposited onto MgO single crystal substrates from a hollow cathode onto ceramic targets with the nominal composition of Bi 2 Sr 2 CaCu 2 O x . Films similar in composition to those used for the targets were deposited on MgO substrates by rf sputtering. The effects of sputtering time, rf power, and post-annealing on film microstructure and properties were studied in detail. Substrate temperature was found to have a significant influence on the film characteristics. Initial results show that deposition rates from a hollow cathode are an order of magnitude higher than those of a planar magnetron source at equivalent power levels. Large deposition rates allow for the coating of long lengths of wire

  2. Reactively sputtered TeOx optical recording media

    International Nuclear Information System (INIS)

    Di Giulio, M.; Manno, D.; Micocci, G.; Rella, R.; Rizzo, A.; Tepore, A.

    1987-01-01

    Telluriom suboxide (TeO x ) thin films have been obtained by R.F. reactive sputtering deposition by using a Te target and an Ar-O 2 gas mixture. This technique of preparation has been shown to be a valid method because it is possible to easily obtain films with desired characteristics by an appropriate selection of the deposition conditions. Different samples were prepared by changing both the R.F. power (80-300 Watt) and the oxygen concentration in the sputtering gas. The films were analyzed in order to study their optical characteristics and the morphology before and after heat treatment. In particular, transmissivity and reflectivity have been found to change markedly by thermal treatment and critical temperatures in the range 120-150 grades centigrade. This property makes these films suitable for optical recording with a low output power laser diode

  3. Dependence of plasma characteristics on dc magnetron sputter parameters

    International Nuclear Information System (INIS)

    Wu, S.Z.

    2005-01-01

    Plasma discharge characteristics of a dc magnetron system were measured by a single Langmuir probe at the center axis of the dual-side process chamber. Plasma potential, floating potential, electron and ion densities, and electron temperature were extracted with varying dc power and gas pressure during sputter deposition of a metal target; strong correlations were shown between these plasma parameters and the sputter parameters. The electron density was controlled mostly by secondary electron generation in constant power mode, while plasma potential reflects the confinement space variation due to change of discharge voltage. When discharge pressure was varied, plasma density increases with the increased amount of free stock molecules, while electron temperature inversely decreased, due to energy-loss collision events. In low-pressure discharges, the electron energy distribution function measurements show more distinctive bi-Maxwellian distribution, with the fast electron temperature gradually decreases with increased gas pressure

  4. Resonance ionization of sputtered atoms: Progress toward a quantitative technique

    International Nuclear Information System (INIS)

    Calaway, W.F.; Pellin, M.J.; Young, C.E.; Whitten, J.E.; Gruen, D.M.; Coon, S.R.; Texas Univ., Austin, TX; Wiens, R.C.; Burnett, D.S.; Stingeder, G.; Grasserbauer, M.

    1992-01-01

    The combination of RIMS and ion sputtering has been heralded as the ideal means of quantitatively probing the surface of a solid. While several laboratories have demonstrated the extreme sensitivity of combining RIMS with sputtering, less effort has been devoted to the question of accuracy. Using the SARISA instrument developed at Argonne National Laboratory, a number of well-characterized metallic samples have been analyzed. Results from these determinations have been compared with data obtained by several other analytical methods. One significant finding is that impurity measurements down to ppb levels in metal matrices can be made quantitative by employing polycrystalline metal foils as calibration standards. This discovery substantially reduces the effort required for quantitative analysis since a single standard can be used for determining concentrations spanning nine orders of magnitude

  5. Collision cascades and sputtering induced by larger cluster ions

    International Nuclear Information System (INIS)

    Sigmund, P.

    1988-01-01

    Recent experimental work on larger cluster impact on solid surfaces suggests large deviations from the standard case of additive sputter yields both in the nuclear and electronic stopping regime. The paper concentrates on elastic collision cascades. In addition to very pronounced spike effects, two phenomena are pointed out that are specific to cluster bombardment. Multiple hits of cluster atoms on one and the same target atom may result in recoil atoms that move faster than the maximum recoil speed for monomer bombardment at the same projectile speed. This effect is important when the atomic mass of a beam atom is less than that of a target atom, M 1 2 . In the opposite case, M 1 >> M 2 , collisions between beam particles may accelerate some beam particles and slow down others. Some consequences are mentioned. Remarks on the nuclear stopping power of larger clusters and on electronic sputtering by cluster bombardment conclude the paper. 38 refs., 2 figs

  6. Corrosion of thin, magnetron sputtered Nb_2O_5 films

    International Nuclear Information System (INIS)

    Pillis, Marina Fuser; Geribola, Guilherme Altomari; Scheidt, Guilherme; Gonçalves de Araújo, Edval; Lopes de Oliveira, Mara Cristina; Antunes, Renato Altobelli

    2016-01-01

    Highlights: • Niobium oxide based films were obtained by DC magnetron sputtering. • Different deposition times were tested. • The best corrosion resistance was obtained for the Nb_2O_5 film produced at 15′. • Film porosity determines the corrosion resistance. - Abstract: Niobium oxide based thin films were deposited on AISI 316 stainless steel substrates using reactive DC magnetron sputtering. Structure, composition and corrosion resistance of the niobium oxide films were studied. The corrosion behavior of the specimens was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The concentration of niobium and oxygen in the films was obtained by Rutherford backscattering spectroscopy (RBS). The film structure was analyzed by X-ray diffractometry. The corrosion resistance of the substrate was improved by the Nb_2O_5 layers. The best protective performance was achieved for the deposition time of 15 min.

  7. Biopolymer nanostructures induced by plasma irradiation and metal sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Slepička, P., E-mail: petr.slepicka@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic); Juřík, P. [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic); Malinský, P.; Macková, A. [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Rez, Prague 25068 (Czech Republic); Faculty of Science, J.E. Purkyně University, Ústí nad Labem (Czech Republic); Kasálková, N. Slepičková; Švorčík, V. [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic)

    2014-08-01

    Modification based on polymer surface exposure to plasma treatment exhibits an easy and cheap technique for polymer surface nanostructuring. The influence of argon plasma treatment on biopolymer poly(L-lactide acid (PLLA) will be presented in this paper. The combination of Ar{sup +} ion irradiation, consequent sputter metallization (platinum) and thermal annealing of polymer surface will be summarized. The surface morphology was studied using atomic force microscopy. The Rutherford Backscattering Spectroscopy and X-ray Photoelectron Spectroscopy were used as analytical methods. The combination of plasma treatment with consequent thermal annealing and/or metal sputtering led to the change of surface morphology and its elemental ratio. The surface roughness and composition has been strongly influenced by the modification parameters and metal layer thickness. By plasma treatment of polymer surface combined with consequent annealing or metal deposition can be prepared materials applicable both in tissue engineering as cell carriers, but also in integrated circuit manufacturing.

  8. Ion-assisted sputter deposition of molybdenum--silicon multilayers

    International Nuclear Information System (INIS)

    Vernon, S.P.; Stearns, D.G.; Rosen, R.S.

    1993-01-01

    X-ray multilayer (ML) structures that are fabricated by the use of magnetron-sputter deposition exhibit a degradation in structural quality as the deposition pressure is increased. The observed change in morphology is attributed to a reduced mobility of surface adsorbed atoms, which inhibits the formation of smooth, continuous layers. The application of a negative substrate bias produces ion bombardment of the growing film surface by sputtering gas ions extracted from the plasma and permits direct control of the energy density supplied to the film surface during thin-film growth. The technique supplements the energy lost to thermalization in high-pressure deposition and permits the fabrication of high-quality ML structures at elevated processing pressures. A threefold improvement in the soft-x-ray normal-incidence reflectance at 130 A results for substrate bias voltages of the order of ∼-150 V for Mo--Si ML's deposited at 10-mTorr Ar

  9. Target surface condition during reactive glow discharge sputtering of copper

    International Nuclear Information System (INIS)

    Depla, D; Haemers, J; Gryse, R De

    2002-01-01

    During reactive glow discharge sputtering of copper in an argon/nitrogen plasma, we noticed an abrupt change of the target voltage and the deposition rate when the nitrogen concentration in the plasma exceeds a critical value. To explain this behaviour, the target surface after reactive glow discharge sputtering was examined by x-ray photoelectron spectroscopy (XPS). An experimental arrangement was constructed that allows direct transfer of the glow discharge cathode to the XPS analysis chamber without air exposure. These XPS measurements revealed that several different chemical states of nitrogen are present in the layer that forms on the target surface. The relative concentration of these different states changes when the critical nitrogen concentration in the plasma is exceeded

  10. Magnetic properties of sputtered Permalloy/molybdenum multilayers

    International Nuclear Information System (INIS)

    Romera, M.; Ciudad, D.; Maicas, M.; Aroca, C.; Ranchal, R.

    2011-01-01

    In this work, we report the magnetic properties of sputtered Permalloy (Py: Ni 80 Fe 20 )/molybdenum (Mo) multilayer thin films. We show that it is possible to maintain a low coercivity and a high permeability in thick sputtered Py films when reducing the out-of-plane component of the anisotropy by inserting thin film spacers of a non-magnetic material like Mo. For these kind of multilayers, we have found coercivities which are close to those for single layer films with no out-of-plane anisotropy. The coercivity is also dependent on the number of layers exhibiting a minimum value when each single Py layer has a thickness close to the transition thickness between Neel and Bloch domain walls.

  11. Modeling of metastable phase formation diagrams for sputtered thin films.

    Science.gov (United States)

    Chang, Keke; Music, Denis; To Baben, Moritz; Lange, Dennis; Bolvardi, Hamid; Schneider, Jochen M

    2016-01-01

    A method to model the metastable phase formation in the Cu-W system based on the critical surface diffusion distance has been developed. The driver for the formation of a second phase is the critical diffusion distance which is dependent on the solubility of W in Cu and on the solubility of Cu in W. Based on comparative theoretical and experimental data, we can describe the relationship between the solubilities and the critical diffusion distances in order to model the metastable phase formation. Metastable phase formation diagrams for Cu-W and Cu-V thin films are predicted and validated by combinatorial magnetron sputtering experiments. The correlative experimental and theoretical research strategy adopted here enables us to efficiently describe the relationship between the solubilities and the critical diffusion distances in order to model the metastable phase formation during magnetron sputtering.

  12. Very low pressure high power impulse triggered magnetron sputtering

    Science.gov (United States)

    Anders, Andre; Andersson, Joakim

    2013-10-29

    A method and apparatus are described for very low pressure high powered magnetron sputtering of a coating onto a substrate. By the method of this invention, both substrate and coating target material are placed into an evacuable chamber, and the chamber pumped to vacuum. Thereafter a series of high impulse voltage pulses are applied to the target. Nearly simultaneously with each pulse, in one embodiment, a small cathodic arc source of the same material as the target is pulsed, triggering a plasma plume proximate to the surface of the target to thereby initiate the magnetron sputtering process. In another embodiment the plasma plume is generated using a pulsed laser aimed to strike an ablation target material positioned near the magnetron target surface.

  13. Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ajaib [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Schipmann, Susanne [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Mathur, Aakash; Pal, Dipayan [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Sengupta, Amartya [Department of Physics, Indian Institute of Technology Delhi, Delhi 110016 (India); Klemradt, Uwe [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Chattopadhyay, Sudeshna, E-mail: sudeshna@iiti.ac.in [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Discipline of Physics, Indian Institute of Technology Indore, Indore 453552 (India); Centre for Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore 453552 (India)

    2017-08-31

    Highlights: • Ultra-thin ZnO films grown on confined polymeric (polystyrene, PS) template. • XRR and GISAXS explore the surface/interfaces structure and morphology of ZnO/PS. • Insights into the growth mechanism of magnetron sputtered ZnO thin film on PS template. • Nucleated disk-like cylindrical particles are the basis of the formation of ZnO layers. • Effect of ZnO film thickness on room temperature PL spectra in ZnO/PS systems. - Abstract: The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (<10 nm) were grown on confined polystyrene with ∼2R{sub g} film thickness, where R{sub g} ∼ 20 nm (R{sub g} is the unperturbed radius of gyration of polystyrene, defined by R{sub g} = 0.272 √M{sub 0}, and M{sub 0} is the molecular weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2–7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

  14. Obsidian hydration profiles measured by sputter-induced optical emission.

    Science.gov (United States)

    Tsong, I S; Houser, C A; Yusef, N A; Messier, R F; White, W B; Michels, J W

    1978-07-28

    The variation of concentrations of hydrogen, sodium, potassium, lithium, calcium, magnesium, silicon, and aluminum as a function of depth in the hydration layer of obsidian artifacts has been determined by sputter-induced optical emission. The surface hydration is accompanied by dealkalization, and there is a buildup of alkaline earths, calcium and magnesium in the outermost layers. These results have clarified the phenomena underlying the obsidian hydration dating technique.

  15. Magnetron co-sputtering system for coating ICF targets

    International Nuclear Information System (INIS)

    Hsieh, E.J.; Meyer, S.F.; Halsey, W.G.; Jameson, G.T.; Wittmayer, F.J.

    1981-01-01

    Fabrication of Inertial Confinement Fusion (ICF) targets requires deposition of various types of coatings on microspheres. The mechanical strength, and surface finish of the coatings are of concern in ICF experiments. The tensile strength of coatings can be controlled through grain refinement, selective doping and alloy formation. We have constructed a magnetron co-sputtering system to produce variable density profile coatings with high tensile strength on microspheres

  16. Ordering process of sputtered FePt films

    International Nuclear Information System (INIS)

    Takahashi, Y.K.; Ohnuma, M.; Hono, K.

    2003-01-01

    We have investigated the in situ ordering process of sputtered FePt thin films deposited on heated substrates at 300 deg. C with different thicknesses. The films thinner than 50 nm were composed of nanograins (∼5 nm) of disordered FePt phase. Recrystallization occurred when films were grown thicker than 100 nm, and transformation twins were observed in recrystallized grains, in which ordering to the L1 0 structure was confirmed

  17. Pumping mechanisms in sputter-ion pumps low pressure operation

    International Nuclear Information System (INIS)

    Welch, K.M.

    1991-01-01

    It is shown that significant H 2 pumping occurs in the walls of triode pumps. Also, H 2 is pumped in the anode cells of sputter-ion pumps. This pumping occurs in a manner similar to that by which the inert gases are pumped. That is, H 2 pumped in the walls of the anode cells by high energy neutral burial. Hydrogen in the pump walls and anodes limits the base pressure of the pump. 13 refs., 5 figs., 1 tab

  18. Pumping mechanisms in sputter-ion pumps low pressure operation

    International Nuclear Information System (INIS)

    Welch, K.M.

    1991-01-01

    It is shown that significant H 2 pumping occurs in the walls of triode pumps. Also, H 2 is pumped in the anode cells of sputter-ion pumps. This pumping occurs in a manner similar to that by which the inert gases are pumped. That is, H 2 is pumped in the walls of the anode cells by high energy neutral burial. Hydrogen in the pump walls and anodes limits the base pressure of the pump

  19. Depth of origin and angular spectrum of sputtered atoms

    International Nuclear Information System (INIS)

    Vicanek, M.; Jimenez Rodriguez, J.J.; Sigmund, P.

    1989-01-01

    A theoretical analysis is presented of the depth of origin of atoms sputtered from a random target. The physical model aims at high energy sputtering under linear cascade conditions and assumes a dilute source of recoil atoms. The initial distribution of the recoils is assumed isotropic, and their energy distribution is E -2 like without an upper or lower cutoff. The scattering medium is either infinite or bounded by a plane surface. Atoms scatter according to the m=0 power cross section. Electronic stopping is ignored. The sputtered flux, differential in depth of origin, ejection energy and ejection angle has been evaluated by Monte Carlo simulation and by five distinct methods of solution of the linear Boltzmann equation reaching from continuous slowing down neglecting angular scattering to the P 3 approximation and a Gram-Charlier expansion going over spatial moments. The continuous slowing down approximation used in previous work leads to results that are identical to those found from a scheme that only ignores angular scattering but allows for energy loss straggling. Moreover, these predictions match more closely with the Monte Carlo results than any of the approximate analytical schemes that take account of angular scattering. The results confirm the common assertion that the depth of origin of sputtered atoms is determined mainly by the stopping of low energy recoil atoms. The effect of angular scattering turns out to be astonishingly small. The distributions in depth of origin, energy, and angle do not depend significantly on whether the scattering medium is a halfspace or an infinite medium with a reference plane. The angular spectrum comes out only very slightly over cosine from the model as it stands, in agreement with previous experience, but comments are made on essential features that are not incorporated in the physical model but might influence the angular spectrum. (orig./WL)

  20. Dependence of sputtering erosion on fuel-pellet characteristics

    International Nuclear Information System (INIS)

    Bohachevsky, I.O.; Hafer, J.F.

    1977-11-01

    Conceptual designs of fusion reactors operating on the principle of inertial confinement require that the dependence of cavity-wall erosion on fuel-pellet energy yield, its mass, and representative atomic number be known. A simple approximate model of sputtering erosion is presented and explicit formulas are derived that express the total amount of eroded wall material in terms of the above three parameters

  1. Effect of sodium aromatic sulfonate group in anionic polymer dispersant on the viscosity of coal-water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Toshio Kakui; Hidehiro Kamiya [Lion Corporation, Tokyo (Japan). Chemicals Research Laboratories, Chemicals Division

    2004-06-01

    This paper focused on the effect of sodium aromatic sulfonate in anionic polymer dispersants on the viscosity of coal-water mixtures (CWMs) with a Tatung coal powder. To determine the optimum molecular structure of a polymer dispersant for the minimum viscosity of a CWM, various anionic co-polymers with different hydrophilic and hydrophobic groups or different molecular weights were prepared, using various types of monomers. Anionic co-polymers with sodium aromatic sulfonate, such as sodium styrene-sulfonate and sodium naphthalene-sulfonate, reduced the viscosity of dense CWMs. In particular, a co-polymer of sodium styrene-sulfonate and sodium acrylate with a molar ratio of 70:30 and a molecular weight of {approximately} 10 000 gave the minimum viscosity of a 70 wt % CWM. To obtain a low viscosity for a CWM, a large electrostatic repulsive force with an absolute value of the zeta potential of the coal particles of {gt} 70 mV and {gt} 6.5 mg/g of adsorbed polymer on the coal surface were needed. The mixture of sodium polystyrene-sulfonate and sodium polyacrylate with a weight ratio of 50:50 also gave a low viscosity of 70 wt % CWM. On the basis of the results, the adsorption behavior of polymer dispersants on the coal surface is examined by measuring the wettability of coal powder pellets. 27 refs., 8 figs., 3 tabs.

  2. Discharge Characteristic of VHF-DC Superimposed Magnetron Sputtering System

    Science.gov (United States)

    Toyoda, Hirotaka; Fukuoka, Yushi; Fukui, Takashi; Takada, Noriharu; Sasai, Kensuke

    2014-10-01

    Magnetron plasmas are one of the most important tools for sputter deposition of thin films. However, energetic particles from the sputtered target such as backscattered rare gas atoms or oxygen negative ions from oxide targets sometimes induce physical and chemical damages as well as surface roughening to the deposited film surface during the sputtering processes. To suppress kinetic energy of such particles, superposition of RF or VHF power to the DC power has been investigated. In this study, influence of the VHF power superposition on the DC target voltage, which is important factor to determine kinetic energy of high energy particles, is investigated. In the study, 40 MHz VHF power was superimposed to an ITO target and decrease in the target DC voltage was measured as well as deposited film deposition properties such as deposition rate or electrical conductivity. From systematic measurement of the target voltage, it was revealed that the target voltage can be determined by a very simple parameter, i.e., a ratio of VHF power to the total input power (DC and VHF powers) in spite of the DC discharge current. Part of this work was supported by ASTEP, JST.

  3. Prototype inverted sputter source for negative heavy ions

    International Nuclear Information System (INIS)

    Minehara, Eisuke; Kobayashi, Chiaki; Kikuchi, Shiroh

    1977-10-01

    A sputter source from which negative heavy ion beam is extracted through a tungsten wire and disc ionizer was built and tested. An alkali metal surface ionization gun with the ionizer is described, and also performance of the surface ionization gun and of the sputter source for negative heavy ions using the gun is reported. The gun was tested for three alkali metals, i.e. sodium, potassium and cesium. Total potassium beam current of 1-2mA was obtained at entrance aperture of the magnet. Sputtering materials and gases for producing negative heavy ions are carbon, copper, aluminium, molybdenum, oxygen and air. With carbon and leakage air, the beam intensities analyzed are: 2-5μA (at Faraday cup) and 4.6-11μA (at exit slit) for C - , 3-5μA (at Faraday cup) and 6.8-11μA (at exit slit) for 2C - , and 11-15μA (at Faraday cup) and 25-34μA (at exit slit) for O - . Total beam current at the entrance aperture was 200-400μA. (auth.)

  4. Binding energy effects in cascade evolution and sputtering

    International Nuclear Information System (INIS)

    Robinson, M.T.

    1995-06-01

    The MARLOWE model was extended to include a binding energy dependent on the local crystalline order, so that atoms are bound less strongly to their lattice sites near surfaces or associated damage. Sputtering and cascade evolution were studied on the examples of self-ion irradiations of Cu and Au monocrystals. In cascades, the mean binding energy is reduced ∼8% in Cu with little dependence on the initial recoil energy; in Au, it is reduced ∼9% at 1 keV and ∼15% at 100 keV. In sputtering, the mean binding energy is reduced ∼8% in Cu and ∼15% in Au with little energy dependence; the yields are increased about half as much. Most sites from which sputtered atoms originate are isolated in both metals. Small clusters of such sites occur in Cu, but there are some large clusters in Au, especially in [111] targets. There are always more large clusters with damage-dependent binding than with a constant binding energy, but only a few clusters are compact enough to be regarded as pits

  5. Monocrystal sputtering by the computer simulation code ACOCT

    International Nuclear Information System (INIS)

    Yamamura, Yasunori; Takeuchi, Wataru.

    1987-09-01

    A new computer code ACOCT has been developed in order to simulate the atomic collisions in the crystalline target within the binary collision approximation. The present code is more convenient as compared with the MARLOWE code, and takes the higher-order simultaneous collisions into account. To cheke the validity of the ACOCT program, we have calculated sputtering yields for various ion-target combinations and compared with the MARLOWE results. It is found that the calculated yields by the ACOCT program are in good agreements with those by the MARLOWE code. The ejection patterns of sputtered atoms were also calculated for the major surfaces of fcc, bcc, diamond and hcp structures, and we have got reasonable agreements with experimental results. In order to know the effects of the simultaneous collision in the slowing down process the sputtering yields and the projected ranges are calculated, changeing the parameter of the criterion for the simultaneous collision, and the effect of the simultaneous collision is found to depend on the crystal orientation. (author)

  6. The crystallization and properties of sputter deposited lithium niobite

    Energy Technology Data Exchange (ETDEWEB)

    Shank, Joshua C.; Brooks Tellekamp, M.; Alan Doolittle, W., E-mail: alan.doolittle@ece.gatech.edu

    2016-06-30

    Sputter deposition of the thin film memristor material, lithium niobite (LiNbO{sub 2}) is performed by co-deposition from a lithium oxide (Li{sub 2}O) and a niobium target. Crystalline films that are textured about the (101) orientation are produced under room temperature conditions. This material displays memristive hysteresis and exhibits XPS spectra similar to MBE and bulk grown LiNbO{sub 2}. Various deposition parameters were investigated resulting in variations in the deposition rate, film crystallinity, oxygen to niobium ratio, and mean niobium oxidation state. The results of this study allow for the routine production of large area LiNbO{sub 2} films at low substrate temperature useful in hybrid-integration of memristor, optical, and energy storage applications. - Highlights: • Room temperature sputter deposition of crystalline lithium niobite (LiNbO{sub 2}) • Contrast with previous high temperature corrosive growth methods • Analysis of sputter deposition parameters on the chemical and physical properties of the deposited material.

  7. The crystallization and properties of sputter deposited lithium niobite

    International Nuclear Information System (INIS)

    Shank, Joshua C.; Brooks Tellekamp, M.; Alan Doolittle, W.

    2016-01-01

    Sputter deposition of the thin film memristor material, lithium niobite (LiNbO_2) is performed by co-deposition from a lithium oxide (Li_2O) and a niobium target. Crystalline films that are textured about the (101) orientation are produced under room temperature conditions. This material displays memristive hysteresis and exhibits XPS spectra similar to MBE and bulk grown LiNbO_2. Various deposition parameters were investigated resulting in variations in the deposition rate, film crystallinity, oxygen to niobium ratio, and mean niobium oxidation state. The results of this study allow for the routine production of large area LiNbO_2 films at low substrate temperature useful in hybrid-integration of memristor, optical, and energy storage applications. - Highlights: • Room temperature sputter deposition of crystalline lithium niobite (LiNbO_2) • Contrast with previous high temperature corrosive growth methods • Analysis of sputter deposition parameters on the chemical and physical properties of the deposited material

  8. High temperature superconducting films by rf magnetron sputtering

    International Nuclear Information System (INIS)

    Kadin, A.M.; Ballentine, P.H.

    1989-01-01

    The authors have produced sputtered films of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O by rf magnetron sputtering from an oxide target consisting of loose reacted powder. The use of a large 8-inch stoichiometric target in the magnetron mode permits films located above the central region to be free of negative-ion resputtering effects, and hence yields reproducible, uniform stoichiometric compositions for a wide range of substrate temperatures. Superconducting YBCO films have been obtained either by sputtering at low temperatures followed by an 850 0 C oxygen anneal, or alternatively by depositing onto substrates heated to ∼600 - 650 0 C and cooling in oxygen. Films prepared by the former method on cubic zirconia substrate consist of randomly oriented crystallites with zero resistance above 83 K. Those deposited on zirconia at medium temperatures without the high-temperature anneal contain smooth partially oriented crystallites, with a slightly depressed T/sub c/ ∼75K. Finally, superconducting films have been deposited on MgO using a BiSrCaCu/sub 2/O/sub x/ powder target

  9. C60 ion sputtering of layered organic materials

    International Nuclear Information System (INIS)

    Shard, Alexander G.; Green, Felicia M.; Gilmore, Ian S.

    2008-01-01

    Two different organic materials, Irganox1010 and Irganox3114, were vacuum deposited as alternating layers. The layers of Irganox3114 were thin (∼2.5 nm) in comparison to the Irganox1010 (∼55 or ∼90 nm); we call these 'organic delta layers'. Both materials are shown to have identical sputtering yields and the alternating layers may be used to determine some of the important metrological parameters for cluster ion beam depth profiling of organic materials. The sputtering yield for C 60 ions is shown to diminish with ion dose. Comparison with atomic force microscopy data from films of pure Irganox1010, demonstrates that the depth resolution is limited by the development of topography. Secondary ion intensities are a well-behaved function of sputtering yield and may be employed to obtain useful analytical information. Organic delta layers are shown to be valuable reference materials for comparing the capabilities of different cluster ion sources and experimental arrangements for the depth profiling of organic materials.

  10. Functional nanostructured titanium nitride films obtained by sputtering magnetron

    International Nuclear Information System (INIS)

    Sanchez, O.; Hernandez-Velez, M.; Navas, D.; Auger, M.A.; Baldonedo, J.L.; Sanz, R.; Pirota, K.R.; Vazquez, M.

    2006-01-01

    Development of new methods in the formation of hollow structures, in particular, nanotubes and nanocages are currently generating a great interest as a consequence of the growing relevance of these nanostructures on many technological fields, ranging from optoelectronics to biotechnology. In this work, we report the formation of titanium nitride (TiN) nanotubes and nanohills via reactive sputtering magnetron processes. Anodic Alumina Membranes (AAM) were used as template substrates to grow the TiN nanostructures. The AAM were obtained through electrochemical anodization processes by using oxalic acid solutions as electrolytes. The nanotubes were produced at temperatures below 100 deg. C, and using a pure titanium (99.995%) sputtering target and nitrogen as reactive gas. The obtained TiN thin films showed surface morphologies adjusted to pore diameter and interpore distance of the substrates, as well as ordered arrays of nanotubes or nanohills depending on the sputtering and template conditions. High Resolution Scanning Electron Microscopy (HRSEM) was used to elucidate both the surface order and morphology of the different grown nanostructures. The crystalline structure of the samples was examined using X-ray Diffraction (XRD) patterns and their qualitative chemical composition by using X-ray Energy Dispersive Spectroscopy (XEDS) in a scanning electron microscopy

  11. An introduction to closed field sputtering (CFS) equipment

    International Nuclear Information System (INIS)

    Sugden, G.B.

    1979-01-01

    Ways have been sought to develop the vacuum sputtering process to reduce the source material temperature and to increase the deposition rate. A new industrial plating method superior to vacuum evaporation and electroplating has emerged. In this 'closed field sputtering' processes an electric field is applied between a coaxial anode and cathode and a magnetic field applied orthogonally to the electric field. Providing the flux density of the magnetic field is above a critical value no electrons flow to the anode but move along the magnetic lines around the cathode, enclosed in the magnetic field. A high density electron cloud with high ionization probability is therefore maintained. Low temperature sputtering can be attained due to very low energy loss of electrons at the anode. A pressure of about (2-5) x 10(-4) torr is used. High power can be applied to the equipment without producing much heat. It enables a large number of plastic parts to be coated with almost any nonmagnetic metal and alloys of metals on a commercial basis. It is also possible to produce coatings of oxides. nitrides and carbides of metals. The method of operation and a description of the equipment are given. Applications include car exteriors, household appliances, furniture toys and the electronics industry. (UK)

  12. Intrinsic photocatalytic assessment of reactively sputtered TiO₂ films.

    Science.gov (United States)

    Rafieian, Damon; Driessen, Rick T; Ogieglo, Wojciech; Lammertink, Rob G H

    2015-04-29

    Thin TiO2 films were prepared by DC magnetron reactive sputtering at different oxygen partial pressures. Depending on the oxygen partial pressure during sputtering, a transition from metallic Ti to TiO2 was identified by spectroscopic ellipsometry. The crystalline nature of the film developed during a subsequent annealing step, resulting in thin anatase TiO2 layers, displaying photocatalytic activity. The intrinsic photocatalytic activity of the catalysts was evaluated for the degradation of methylene blue (MB) using a microfluidic reactor. A numerical model was employed to extract the intrinsic reaction rate constants. High conversion rates (90% degradation within 20 s residence time) were observed within these microreactors because of the efficient mass transport and light distribution. To evaluate the intrinsic reaction kinetics, we argue that mass transport has to be accounted for. The obtained surface reaction rate constants demonstrate very high reactivity for the sputtered TiO2 films. Only for the thinnest film, 9 nm, slightly lower kinetics were observed.

  13. Sputter deposited gallium doped ZnO for TCO applications

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Marc; Kronenberger, Achim; Polity, Angelika; Meyer, Bruno [I. Physikalisches Institut, Justus Liebig Universitaet Giessen (Germany); Blaesing, Juergen; Krost, Alois [FNW/IEP/AHE, Otto-von-Guericke Universitaet Magdeburg (Germany)

    2010-07-01

    Transparent conducting oxides to be used for flat panel or display applications should exhibit low electrical resistivity in line with a high optical transmission in the visible spectral range. Today indium-tin-oxide is the material which meets these requirements best. However, the limited availability of indium makes it useful to search for alternatives and ZnO doped with group III elements are promising candidates. While the Al doping in high concentrations causes problems due to the formation of insulating Al-oxides, Gallium related oxides are typically n-type conducting wide band gap semiconductors. Therefore we deposited Gallium doped ZnO thin films on quartz and sapphire substrates by radio frequency magnetron sputtering with a ZnO/Ga{sub 2}O{sub 3}(3at%) composite target. The substrate temperature and the oxygen flow during the sputtering process were varied to optimise the layer properties. Introducing oxygen to the sputtering gas allowed to vary the resistivity of the films by three orders of magnitude from about 1 {omega}cm down to less than 1 m{omega}cm.

  14. Assessing Reliability of Cold Spray Sputter Targets in Photovoltaic Manufacturing

    Science.gov (United States)

    Hardikar, Kedar; Vlcek, Johannes; Bheemreddy, Venkata; Juliano, Daniel

    2017-10-01

    Cold spray has been used to manufacture more than 800 Cu-In-Ga (CIG) sputter targets for deposition of high-efficiency photovoltaic thin films. It is a preferred technique since it enables high deposit purity and transfer of non-equilibrium alloy states to the target material. In this work, an integrated approach to reliability assessment of such targets with deposit weight in excess of 50 lb. is undertaken, involving thermal-mechanical characterization of the material in as-deposited condition, characterization of the interface adhesion on cylindrical substrate in as-deposited condition, and developing means to assess target integrity under thermal-mechanical loads during the physical vapor deposition (PVD) sputtering process. Mechanical characterization of cold spray deposited CIG alloy is accomplished through the use of indentation testing and adaptation of Brazilian disk test. A custom lever test was developed to characterize adhesion along the cylindrical interface between the CIG deposit and cylindrical substrate, overcoming limitations of current standards. A cohesive zone model for crack initiation and propagation at the deposit interface is developed and validated using the lever test and later used to simulate the potential catastrophic target failure in the PVD process. It is shown that this approach enables reliability assessment of sputter targets and improves robustness.

  15. Arc generation from sputtering plasma-dielectric inclusion interactions

    CERN Document Server

    Wickersham, C E J; Fan, J S

    2002-01-01

    Arcing during sputter deposition and etching is a significant cause of particle defect generation during device fabrication. In this article we report on the effect of aluminum oxide inclusion size, shape, and orientation on the propensity for arcing during sputtering of aluminum targets. The size, shape, and orientation of a dielectric inclusion plays a major role in determining the propensity for arcing and macroparticle emission. In previous studies we found that there is a critical inclusion size required for arcing to occur. In this article we used high-speed videos, electric arc detection, and measurements of particle defect density on wafers to study the effect of Al sub 2 O sub 3 inclusion size, shape, and orientation on arc rate, intensity, and silicon wafer particle defect density. We found that the cross-sectional area of the inclusion exposed to the sputtering plasma is the critical parameter that determines the arc rate and rate of macroparticle emission. Analysis of the arc rate, particle defect...

  16. Preparation and characterization of thick metastable sputter deposits

    International Nuclear Information System (INIS)

    Allen, R.P.; Dahlgren, S.D.; Merz, M.D.

    1975-01-01

    High-rate dc supported-discharge sputtering techniques were developed and used to prepare 0.1 mm to 5.0 mm-thick deposits of a variety of metastable materials including amorphous alloys representing more than 15 different rare-earth-transition metal systems and a wide range of compositions and deposition conditions. The ability to prepare thick, homogeneous deposits has made it possible for the first time to investigate the structure, properties, and annealing behavior of these unique sputtered alloys using neutron diffraction, ultrasonic, and other experimental techniques that are difficult or impractical for thin films. More importantly, these characterization studies show that the structure and properties of the massive sputter deposits are independent of thickness and can be reproduced from deposit to deposit. Other advantages and applications of this metastable materials preparation technique include the possibility of varying structure and properties by control of the deposition parameters and the ability to deposit even reactive alloys with a very low impurity content

  17. Properties of tungsten films prepared by magnetron sputtering

    International Nuclear Information System (INIS)

    Ahn, K.Y.; Ting, C.Y.; Brodsky, S.B.; Fryer, P.M.; Davari, B.; Angillelo, J.; Herd, S.R.; Licata, T.

    1986-01-01

    High-rate magnetron sputtering is a relatively simple process to produce tungsten films with good electrical and mechanical properties, and it offers good uniformity, reproducibility, process flexibility, and high throughput. The purity of the sputtered films is affected by the target purity (cold-pressed 99.95%, chemical vapor deposited 99.99% and cast 99.999%), base pressure, deposition rate, and substrate bias. Typical resistivity in films of 2000 to 3000A thickness deposited on Si, poly-Si, and SiO/sub 2/ ranges from 10 to 12 μΩ-cm, and this may be compared with 6 and 11 μΩ-cm by high-temperature evaporation and chemical vapor deposition, respectively. The presence of biaxial stress caused by substrate scanning was determined by x-ray technique. The sputtered films exhibit high compressive stress when deposited at low Ar pressure. It decreases with increasing pressure, and eventually changes sign to become tensile, and increases further with increasing pressure. Effects of processing parameters on films properties, and a comparison of film properties prepared by evaporation and chemical vapor deposition are discussed

  18. Sequential sputtered Co-HfO{sub 2} granular films

    Energy Technology Data Exchange (ETDEWEB)

    Chadha, M.; Ng, V.

    2017-03-15

    A systematic study of magnetic, magneto-transport and micro-structural properties of Co-HfO{sub 2} granular films fabricated by sequential sputtering is presented. We demonstrate reduction in ferromagnetic-oxide formation by using HfO{sub 2} as the insulting matrix. Microstructure evaluation of the films showed that the film structure consisted of discrete hcp-Co grains embedded in HfO{sub 2} matrix. Films with varying compositions were prepared and their macroscopic properties were studied. We correlate the variation in these properties to the variation in film microstructure. Our study shows that Co-HfO{sub 2} films with reduced cobalt oxide and varying properties can be prepared using sequential sputtering technique. - Highlights: • Co-HfO{sub 2} granular films were prepared using sequential sputtering. • A reduction in ferromagnetic-oxide formation is observed. • Co-HfO{sub 2} films display superparamagnetism and tunnelling magneto-resistance. • Varying macroscopic properties were achieved by changing film composition. • Applications can be found in moderate MR sensors and high –frequency RF devices.

  19. Nitrate Anion Exchange in Pu-238 Aqueous Scrap Recovery Operations

    International Nuclear Information System (INIS)

    Pansoy-Hjelvik, M.E.; Silver, G.L.; Reimus, M.A.H.; Ramsey, K.B.

    1999-01-01

    Strong base, nitrate anion exchange (IX) is crucial to the purification of 238 Pu solution feedstocks with gross levels of impurities. This paper discusses the work involved in bench scale experiments to optimize the nitrate anion exchange process. In particular, results are presented of experiments conducted to (a) demonstrate that high levels of impurities can be separated from 238 Pu solutions via nitrate anion exchange and, (b) work out chemical pretreatment methodology to adjust and maintain 238 Pu in the IV oxidation state to optimize the Pu(IV)-hexanitrato anionic complex sorption to Reillex-HPQ resin. Additional experiments performed to determine the best chemical treatment methodology to enhance recovery of sorbed Pu from the resin, and VIS-NIR absorption studies to determine the steady state equilibrium of Pu(IV), Pu(III), and Pu(VI) in nitric acid are discussed

  20. Dehydroabiethylamine acetate as metal-containing anion precipitant

    International Nuclear Information System (INIS)

    Skrylev, L.D.; Borisov, V.A.

    1979-01-01

    The precipitation is studied of vanadate, tungstate-, molybdate- and chromate-ions by dehydroabiethylamine acetate. The degree of precipitation of metal-bearing anions is a function of the anion and of pH of the treated solutions. There exists a predetermined value of pH for each anion, at which the content of metal-bearing anion in the ultra-filtrate is at a minimum. For vanadate-ions, this pH is 5.0; for tungstate-ions, 3.0; for molybdate-ions, 4.0; for chrommate-ions, 8.0. The heats of solution of methavanadate, paratungstate, paramolybdate and dehydroabiethylamine chromate, calculated in accordance with the Vant-Hoff equation, range between 3.5 and 8.3 kJ/mole; free energy varies between 45.8 and 137.5 kJ/mole; and entropy varies between 110 and 371 J/degree mole