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Sample records for al br cl

  1. Ab initio study on the electronic states and laser cooling of AlCl and AlBr

    NASA Astrophysics Data System (ADS)

    Rong, Yang; Bin, Tang; Tao, Gao

    2016-04-01

    We investigate whether AlCl and AlBr are promising candidates for laser cooling. We report new ab initio calculations on the ground state X1Σ+ and two low-lying states (A1Π and a3Π) of AlCl and AlBr. The calculated spectroscopic constants show good agreement with available theoretical and experimental results. We also obtain the permanent dipole moments (PDMs) curve at multi-reference configuration interaction (MRCI) level of theory. The transition properties of A1Π and a3Π states are predicted, including the transition dipole moments (TDMs), Franck-Condon factors (FCFs), radiative times and radiative width. The calculated radiative lifetimes are of the order of a nanosecond, implying that they are sufficiently short for rapid laser cooling. Both AlCl and AlBr have highly diagonally distributed FCFs which are crucial requirement for molecular laser cooling. The results demonstrate the feasibility of laser cooling AlCl and AlBr, and we propose laser cooling schemes for AlCl and AlBr.

  2. Matrix reactivity of AlF and AlCl in the presence of HCl and HBr: generation and characterization of the new Al(III) hydrides HAlFCl, HAlFBr, and HAlClBr and the monomeric mixed Al(III) halides AlX(2)Y (X, Y = F, Cl, or Br).

    PubMed

    Himmel, Hans-Jörg; Bahlo, Jan; Haussmann, Michael; Kurth, Fabian; Stösser, Gregor; Schnöckel, Hansgeorg

    2002-09-23

    The spontaneous and photolytically induced reactions of AlF and AlCl in the presence of HCl and HBr in solid argon matrices were followed and the products identified and characterized by means of IR spectroscopy. Quantum mechanical calculations allow for a further evaluation of the properties of the reaction products. These are the adducts AlF.HCl, AlF.HBr, and AlCl.HBr, representing the products of spontaneous reactions, and the trivalent Al(III) hydrides HAlFCl, HAlFBr, and HAlClBr, which were formed upon photoactivation of these complexes. All three hydrides are planar molecules (C(s)() symmetry) with bond angles in agreement with the predictions of the VSEPR theory. In addition, the mixed halides AlFCl(2), AlFBr(2), and AlClBr(2) were formed upon photolysis. The bisadducts AlF.(HCl)(2) and AlF.(HBr)(2) are likely to be the precursors to these species.

  3. Modification of LiCl-LiBr-KBr electrolyte for LiAl/FeS{sub 2} batteries

    SciTech Connect

    Kaun, T.D.; Jansen, A.N.; Henriksen, G.L.; Vissers, D.R.

    1996-06-01

    The bipolar LiAl/FeS{sub 2} battery is being developed to achieve the high performance and long cycle life needed for electric vehicle application. The molten-salt (400 to 440 C operation) electrolyte composition for this battery has evolved to support these objectives. An earlier change to LiCl-LiBr-KBr electrolyte is responsible for significantly increased cycle life (up to 1,000 cycles). Recent electrolyte modification has significantly improved cell performance; approximately 50% increased power, with increased high rate capacity utilization. Results are based on power-demanding EV driving profile test at 600 W/kg. The effects of adding small amounts (1--5 mol%) of LiF and LiI to LiCl-LiBr-KBr electrolyte are discussed. By cyclic voltammetry, the modified electrolytes exhibit improved FeS{sub 2} electrochemistry. Electrolyte conductivity is little changed, but high current density (200 mA/cm{sup 2}) performance improved by approximately 50%. A specific feature of the LiI addition is an enhanced cell overcharge tolerance rate from 2.5 to 5 mA/cm{sup 2}. The rate of overcharge tolerance is related to electrolyte properties and negative electrode lithium activity. As a result, the charge balancing of a bipolar battery configuration with molten-salt electrolyte is improved to accept greater cell-to-cell deviations.

  4. High temporal resolution Br2, BrCl and BrO observations in coastal Antarctica

    NASA Astrophysics Data System (ADS)

    Buys, Z.; Brough, N.; Huey, L. G.; Tanner, D. J.; von Glasow, R.; Jones, A. E.

    2013-02-01

    There are few observations of speciated inorganic bromine in polar regions against which to test current theory. Here we report the first high temporal resolution measurements of Br2, BrCl and BrO in coastal Antarctica, made at Halley during spring 2007 using a Chemical Ionisation Mass Spectrometer (CIMS). We find indications for an artefact in daytime BrCl measurements arising from conversion of HOBr, similar to that already identified for observations of Br2 made using a similar CIMS method. Using the MISTRA model, we estimate that the artefact represents a conversion of HOBr to Br2 of the order of several tens of percent, while that for HOBr to BrCl is less but non-negligible. If the artefact is indeed due to HOBr conversion, then nighttime observations were unaffected. It also appears that all daytime BrO observations were artefact-free. Mixing ratios of BrO, Br2 and BrCl ranged from instrumental detection limits to 13 pptv (daytime), 45 pptv (nighttime), and 6 pptv (nighttime), respectively. We see considerable variability in the Br2 and BrCl observations over the measurement period which is strongly linked to the prevailing meteorology, and thus air mass origin. Higher mixing ratios of these species were generally observed when air had passed over the sea-ice zone prior to arrival at Halley, than from over the continent. Variation in the diurnal structure of BrO is linked to previous model work where differences in the photolysis spectra of Br2 and O3 is suggested to lead to a BrO maximum at sunrise and sunset, rather than a noon-time maxima. This suite of Antarctic data provides the first analogue to similar measurements made in the Arctic, and of note is that our maximum measured BrCl (nighttime) is less than half of the maximum measured during a similar period (spring-time) in the Arctic (also nighttime). This difference in maximum measured BrCl may also be the cause of a difference in the Br2 : BrCl ratio between the Arctic and Antarctic. An unusual event

  5. Br2, BrCl, BrO and surface ozone in coastal Antarctica: a meteorological and chemical analysis

    NASA Astrophysics Data System (ADS)

    Buys, Z.; Brough, N.; Huey, G.; Tanner, D.; von Glasow, R.; Jones, A. E.

    2012-04-01

    There is much debate over the source of bromine radicals in the atmosphere that drives polar boundary layer ozone depletion events (ODEs), but there is strong evidence to suggest a source associated with the sea ice zone. Here we report the first high temporal resolution measurements of Br2, BrCl and BrO in coastal Antarctica, made using a Chemical Ionisation Mass Spectrometer (CIMS). Mixing ratios ranged from instrumental detection limits to 13 pptv for BrO, 45 pptv for Br2, and 6 pptv for BrCl. We find evidence for blowing snow as a source of reactive bromine both directly during a storm and subsequently from recycling of bromide deposited on the continental snowpack. An unusual event of trans-continental air mass transport might have been responsible for severe surface ozone depletion observed at Halley. The halogen source region was the Bellingshausen Sea, to the west of the Antarctic Peninsula, the air mass having spent 3 1/2 days in complete darkness prior to arrival at Halley. We, further, identify an artefact in daytime BrCl measurements arising from conversion of HOBr, similar to that already identified for CIMS observations of Br2. Model calculations using the MISTRA 0-D model suggest a 50-60% conversion of HOBr to Br2, and 5-10% conversion to BrCl. Careful data filtering enabled us to use the halogen observations, in conjunction with the MISTRA model, to explore the temperature dependence of the Br2:BrCl ratio. We find evidence of a ratio shift towards Br2 at temperatures below ~-21 °C, suggesting a relationship with hydrohalite (NaCl.2H2O) precipitation. This suite of Antarctic data provides the first analogue to similar measurements made in the Arctic.

  6. Crystal structures of hydrates of simple inorganic salts. III. Water-rich aluminium halide hydrates: AlCl3 · 15H2O, AlBr3 · 15H2O, AlI3 · 15H2O, AlI3 · 17H2O and AlBr3 · 9H2O.

    PubMed

    Schmidt, Horst; Hennings, Erik; Voigt, Wolfgang

    2014-09-01

    Water-rich aluminium halide hydrate structures are not known in the literature. The highest known water content per Al atom is nine for the perchlorate and fluoride. The nonahydrate of aluminium bromide, stable pentadecahydrates of aluminium chloride, bromide and iodide, and a metastable heptadecahydrate of the iodide have now been crystallized from low-temperature solutions. The structures of these hydrates were determined and are discussed in terms of the development of cation hydration spheres. The pentadecahydrate of the chloride and bromide are isostructural. In AlI(3) · 15H2O, half of the Al(3+) cations are surrounded by two complete hydration spheres, with six H2O in the primary and 12 in the secondary. For the heptadecahydrate of aluminium iodide, this hydration was found for every Al(3+).

  7. Polymorphism in 2-X-adamantane derivatives (X = Cl, Br).

    PubMed

    Negrier, Philippe; Barrio, María; Tamarit, Josep Ll; Mondieig, Denise

    2014-08-14

    The polymorphism of two 2-X-adamantane derivatives, X = Cl, X = Br, has been studied by X-ray powder diffraction and normal- and high-pressure (up to 300 MPa) differential scanning calorimetry. 2-Br-adamantane displays a low-temperature orthorhombic phase (space group P212121, Z = 4) and a high-temperature plastic phase (Fm3̅m, Z = 4) from 277.9 ± 1.0 K to the melting point at 413.4 ± 1.0 K. 2-Cl-adamantane presents a richer polymorphic behavior through the temperature range studied. At low temperature it displays a triclinic phase (P1̅, Z = 2), which transforms to a monoclinic phase (C2/c, Z = 8) at 224.4 ± 1.0 K, both phases being ordered. Two high-temperature orientationally disordered are found for this compound, one hexagonal (P63/mcm, Z = 6) at ca. 241 K and the highest one, cubic (Fm3̅m, Z = 4), being stable from 244 ± 1.0 K up to the melting point at 467.5 ± 1.0 K. No additional phase appears due to the increase in pressure within the studied range. The intermolecular interactions are found to be weak, especially for the 2-Br-adamantane compound for which the Br···Br as well as C-Br···H distances are larger than the addition of the van der Waals radii, thus confirming the availability of this compound for building up diamondoid blocks.

  8. BrCl production in NaBr/NaCl/HNO3/O3 solutions representative of sea-salt aerosols in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Disselkamp, R. S.; Chapman, E. G.; Barchet, W. R.; Colson, S. D.; Howd, C. D.

    Atomic bromine and chlorine liberated from sea-salt aerosol is thought to play an important role in chemistry of the marine boundary layer. Despite numerous modeling studies, no prior experimental investigations of the oxidation of halide species contained in simulated, or actual, sea-salt solutions have been performed. We present laboratory data that examines chemistry in NaBr/NaCl/HNO3/O3 solutions at 290 K. Ozonation experiments were performed by flowing ozone in air through a nitric acid/salt solution and monitoring pH with time using an ion-sensitive electrode. The rate of oxidation was observed to be first order in ozone concentration and to have a non-first order bromide concentration dependence. Ion Chromatography was used to measure both bromide disappearance as well as oxidation products formed during the course of the reactions studied. Our measurements of the oxidation rate versus ion concentration indicate that the high ionic strength present in sea-salt aerosol will possess unique kinetics different from dilute solution behavior. In addition, our results are consistent with the reaction sequence O3 + H+ + Br- → O2 + HOBr and HOBr + Cl- + H+ → BrCl + H2O. These observations support the HOBr mediated Cl- oxidation process proposed previously (Vogt et al., 1996).

  9. Millimeter wave measurements of the rotational spectra of ClF, BrF, BrCl, ICl, and IBr

    NASA Astrophysics Data System (ADS)

    Willis, Robert E.; Clark, William W.

    1980-05-01

    The rotational spectra of all twelve stable isotopic species of ClF, BrF, BrCl, ICl, and IBr were observed and measured in the millimeter wave region by means of a sensitive microwave spectrometer. Transitions were detected over a wide range of frequencies for molecules in both the ground vibrational state and several excited states. The rotational spectrum of each molecule was split by the nuclear quadrupole interaction. Altogether, 250 new lines were measured. These correspond to 136 pure rotational transitions. Values of the Dunham coefficients Y01, Y11, Y21, Y31, Y02, Y12, and Y03 were obtained from a computer analysis of the measured frequencies. From these coefficients a number of equilibrium constants were derived to significantly greater accuracy than in previous work. In particular, the equilibrium distance, re, was found to two or three more significant figures.

  10. Geometries and energy separations of electronic states of AsCl2, AsBr2, AsCl2+, and AsBr2+

    NASA Astrophysics Data System (ADS)

    Latifzadeh-Masoudipour, Lida; Balasubramanian, K.

    1997-02-01

    Spectroscopic properties of the low-lying 2B1, 2A1, 2A2, 4A2, 2B1(II), 4B1, 2B2(I), 2B2(II) electronic states of AsCl2 and AsBr2 have been studied with the complete active space self-consistent field (CASSCF) followed by multireference singles and doubles configuration interaction (MRSDCI) methods. In addition, the three low-lying electronic states of AsCl2+ and AsBr2+, (1A1,3B1,1B1) and the ground states of AsCl and AsBr were investigated. The bond dissociation energies of AsCl2, AsBr2, AsCl, and AsBr have been computed at the CASSCF/MRSDCI and CASSCF/second order configuration interaction (SOCI) levels as De(ClAs-Cl)=2.56 eV, De(BrAs-Br)=1.96 eV, De(As-Cl)=2.68 eV, and De(As-Br)=2.26 eV. The adiabatic ionization energies obtained in this work are 8.40 eV for AsCl2 and 8.33 eV for AsBr2. All these species have been found to possess bent geometries at their ground electronic states.

  11. Studies of ClO and BrO reactions important in the polar stratosphere: Kinetics and mechanism of the ClO+BrO and ClO+ClO reactions

    NASA Technical Reports Server (NTRS)

    Friedl, Randall R.; Sander, Stanley P.

    1988-01-01

    The reactions, BrO + ClO yields Br + ClOO (1a) yields Br + OClO (1b) yields BrCl + O2 (1c) and ClO + ClO yields Cl + CiOO (2a) yields Cl + OClO (2b) yields Cl2 + O2 (2c) yields (ClO)2 (2d) have assumed new importance in explaining the unusual springtime depletion of ozone observed in the Antarctic stratosphere. The mechanisms of these reactions involve the formation of metastable intermediates which subsequently decompose through several energetically allowed products providing the motivation to study these reactions using both the discharge flow-mass spectrometric and flash photolysis - ultraviolet absorption techniques. These methods have also been used to explore aspects of the kinetics and spectroscopy of the ClO dimer.

  12. Global impacts of tropospheric halogens (Cl, Br, I) on oxidants and composition in GEOS-Chem

    NASA Astrophysics Data System (ADS)

    Sherwen, Tomás; Schmidt, Johan A.; Evans, Mat J.; Carpenter, Lucy J.; Großmann, Katja; Eastham, Sebastian D.; Jacob, Daniel J.; Dix, Barbara; Koenig, Theodore K.; Sinreich, Roman; Ortega, Ivan; Volkamer, Rainer; Saiz-Lopez, Alfonso; Prados-Roman, Cristina; Mahajan, Anoop S.; Ordóñez, Carlos

    2016-09-01

    We present a simulation of the global present-day composition of the troposphere which includes the chemistry of halogens (Cl, Br, I). Building on previous work within the GEOS-Chem model we include emissions of inorganic iodine from the oceans, anthropogenic and biogenic sources of halogenated gases, gas phase chemistry, and a parameterised approach to heterogeneous halogen chemistry. Consistent with Schmidt et al. (2016) we do not include sea-salt debromination. Observations of halogen radicals (BrO, IO) are sparse but the model has some skill in reproducing these. Modelled IO shows both high and low biases when compared to different datasets, but BrO concentrations appear to be modelled low. Comparisons to the very sparse observations dataset of reactive Cl species suggest the model represents a lower limit of the impacts of these species, likely due to underestimates in emissions and therefore burdens. Inclusion of Cl, Br, and I results in a general improvement in simulation of ozone (O3) concentrations, except in polar regions where the model now underestimates O3 concentrations. Halogen chemistry reduces the global tropospheric O3 burden by 18.6 %, with the O3 lifetime reducing from 26 to 22 days. Global mean OH concentrations of 1.28 × 106 molecules cm-3 are 8.2 % lower than in a simulation without halogens, leading to an increase in the CH4 lifetime (10.8 %) due to OH oxidation from 7.47 to 8.28 years. Oxidation of CH4 by Cl is small (˜ 2 %) but Cl oxidation of other VOCs (ethane, acetone, and propane) can be significant (˜ 15-27 %). Oxidation of VOCs by Br is smaller, representing 3.9 % of the loss of acetaldehyde and 0.9 % of the loss of formaldehyde.

  13. Combined vacuum ultraviolet laser and synchrotron pulsed field ionization study of CH2BrCl.

    PubMed

    Li, Juan; Yang, Jie; Mo, Yuxiang; Lau, K C; Qian, X M; Song, Y; Liu, Jianbo; Ng, C Y

    2007-05-14

    The pulsed field ionization-photoelectron (PFI-PE) spectrum of bromochloromethane (CH2BrCl) in the region of 85,320-88,200 cm-1 has been measured using vacuum ultraviolet laser. The vibrational structure resolved in the PFI-PE spectrum was assigned based on ab initio quantum chemical calculations and Franck-Condon factor predictions. At energies 0-1400 cm-1 above the adiabatic ionization energy (IE) of CH2BrCl, the Br-C-Cl bending vibration progression (nu1+=0-8) of CH2BrCl+ is well resolved and constitutes the major structure in the PFI-PE spectrum, whereas the spectrum at energies 1400-2600 cm-1 above the IE(CH2BrCl) is found to exhibit complex vibrational features, suggesting perturbation by the low lying excited CH2BrCl+(A 2A") state. The assignment of the PFI-PE vibrational bands gives the IE(CH2BrCl)=85,612.4+/-2.0 cm-1 (10.6146+/-0.0003 eV) and the bending frequencies nu1+(a1')=209.7+/-2.0 cm-1 for CH2BrCl+(X2A'). We have also examined the dissociative photoionization process, CH2BrCl+hnu-->CH2Cl++Br+e-, in the energy range of 11.36-11.57 eV using the synchrotron based PFI-PE-photoion coincidence method, yielding the 0 K threshold or appearance energy AE(CH2Cl+)=11.509+/-0.002 eV. Combining the 0 K AE(CH2Cl+) and IE(CH2BrCl) values obtained in this study, together with the known IE(CH2Cl), we have determined the 0 K bond dissociation energies (D0) for CH2Cl+-Br (0.894+/-0.002 eV) and CH2Cl-Br (2.76+/-0.01 eV). We have also performed CCSD(T, full)/complete basis set (CBS) calculations with high-level corrections for the predictions of the IE(CH2BrCl), AE(CH2Cl+), IE(CH2Cl), D0(CH2Cl+-Br), and D0(CH2Cl-Br). The comparison between the theoretical predictions and experimental determinations indicates that the CCSD(T, full)/CBS calculations with high-level corrections are highly reliable with estimated error limits of <17 meV.

  14. Isotope fractionation in aqua-gas systems: Cl(2)-HCl-Cl(-), Br(2)-HBr-Br(-) and H(2)S-S(2-).

    PubMed

    Czarnacki, Maciej; Hałas, Stanisław

    2012-01-01

    We report calculated values of isotope fractionation factors between chlorine, bromine and sulphide hydrated anions and respective gaseous compounds: hydrogen chloride, hydrogen bromide, molecular chlorine and bromine and hydrogen sulphide. For the calculation of the reduced partition function ratios (β-factors) of hydrated Cl(-), Br(-) and S(2-) anions, we used a model of a cluster composed of the considered ion surrounded by two shells of H(2)O molecules. Only the electrostatic interaction between ion and water molecules treated as electric dipoles was taken into account. The β-factors for the gaseous compounds (HCl, Cl(2), HBr, Br(2) and H(2)S) were calculated from vibrational frequencies reported by Urey and Greiff [Isotopic Exchange Equilibria, J. Am. Chem. Soc. 57, 321 (1935)] and Schauble et al. [Theoretical Estimates Equilibrium Chlorine-Isotope Fractionation, Geochim. Cosmochim. Acta 67, 3267 (2003)]. Low-temperature isotope fractionation between chlorine-hydrated anion and hydrogen chloride attains 1.55-1.68‰ (this work), which is in good agreement with experimental data (1.4-1.8‰) [Z.D. Sharp, J.D. Barnes, T.P. Fischer and M. Halick, An Experimental Determination of Chlorine Isotope Fractionation in Acid Systems and Applications to Volcanic Fumaroles, Geochim. Cosmochim. Acta 74, 264 (2010)]. The predicted isotope fractionations for hydrated bromine and HBr, Br(2) gases are very small, 1000 ln α, do not exceed 0.8‰; thus, the expected variations of bromine isotope composition in aqua-gas systems will require enhanced precision for their detection. In contrast, the sulphur isotope fractionation between H(2)S( gas ) and S(2-) attains 6.0‰ at room temperature and drops nearly linearly to 3.1‰ at 350°C.

  15. Br/Cl partitioning in chloride minerals in the Burns formation on Mars

    NASA Astrophysics Data System (ADS)

    Marion, G. M.; Catling, D. C.; Kargel, J. S.

    2009-04-01

    Within Gusev Crater and Meridiani Planum on Mars, the Mars exploration rovers have found Br concentrations in soils and rocks in the hundreds of ppm range. Relative to Earth compositions, these are high Br concentrations. Because of low Br concentrations on Earth, Br largely precipitates from seawater as a minor constituent in halite crystals rather than as a separate phase mineral. This is also likely to be the case for Mars. But given that the surface chemistries on Mars are significantly different than on Earth, minerals other than halite could serve as sinks for Br. The specific objectives of this paper were to (1) incorporate Br solution phase chemistries into the FREZCHEM model, (2) integrate the Siemann-Schramm Br/Cl mineral model into FREZCHEM, and (3) apply this mineral model to Br/Cl partitioning in Burns formation rocks as an indicator of past environments in the Meridiani Planum region of Mars. We showed that: (1) a molar-based model for Br substitution into halite and bischofite provided a better fit to experimental data than the standard mass-based model; (2) the concentrations of all of the soluble salts (mainly of Na, Mg, Ca, Cl, Br, and SO 4) in the Burns formation, except for Ca, were significantly related to stratigraphic depth; (3) the likely precipitation of Ca as gypsum on Mars precluded Ca precipitating as a CaCl 2 salt and thus impacts the possible minimum eutectic brine temperatures relevant to the Burns formation; (4) bischofite (MgCl 2ṡ6H 2O) was a much more important sink for Br than halite; (5) Br/Cl patterns in the Burns formation, and within the three formation layers, argued in support of salt upwelling through groundwater evaporation; and (6) the high concentrations of Br in the surface layers of the Burns formation suggested that there was little water leaching and removal of soluble phases from the upper part of the stratigraphic succession.

  16. Molecular dynamics simulations of Si etching in Cl- and Br-based plasmas: Cl{sup +} and Br{sup +} ion incidence in the presence of Cl and Br neutrals

    SciTech Connect

    Nakazaki, Nobuya Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2015-12-21

    Classical molecular dynamics (MD) simulations have been performed for Cl{sup +} and Br{sup +} ions incident on Si(100) surfaces with Cl and Br neutrals, respectively, to gain a better understanding of the ion-enhanced surface reaction kinetics during Si etching in Cl- and Br-based plasmas. The ions were incident normally on surfaces with translational energies in the range E{sub i} = 20–500 eV, and low-energy neutrals of E{sub n} = 0.01 eV were also incident normally thereon with the neutral-to-ion flux ratio in the range Γ{sub n}{sup 0}/Γ{sub i}{sup 0} = 0–100, where an improved Stillinger--Weber potential form was employed for the interatomic potential concerned. The etch yields and thresholds presently simulated were in agreement with the experimental results previously reported for Si etching in Cl{sub 2} and Br{sub 2} plasmas as well as in Cl{sup +}, Cl{sub 2}{sup +}, and Br{sup +} beams, and the product stoichiometry simulated was consistent with that observed during Ar{sup +} beam incidence on Si in Cl{sub 2}. Moreover, the surface coverage of halogen atoms, halogenated layer thickness, surface stoichiometry, and depth profile of surface products simulated for Γ{sub n}{sup 0}/Γ{sub i}{sup 0} = 100 were in excellent agreement with the observations depending on E{sub i} reported for Si etching in Cl{sub 2} plasmas. The MD also indicated that the yield, coverage, and surface layer thickness are smaller in Si/Br than in Si/Cl system, while the percentage of higher halogenated species in product and surface stoichiometries is larger in Si/Br. The MD further indicated that in both systems, the translational energy distributions of products and halogen adsorbates desorbed from surfaces are approximated by two Maxwellians of temperature T{sub 1} ≈ 2500 K and T{sub 2} ≈ 7000–40 000 K. These energy distributions are discussed in terms of the desorption or evaporation from hot spots formed through chemically enhanced physical

  17. Solubility of Li/sub 2/S in LiF-LiCl-LiBr electrolyte: measurements and calculations

    SciTech Connect

    Tomczuk, Z.; Vissers, D.R.; Saboungi, M.L.

    1983-01-01

    High performance lithium-alloy/iron sulfide cells are currently being developed at Argonne National Laboratory and at several industrial firms for electric vehicle propulsion. These cells operate at high temperatures and utilize Li-Al or Li-Si negative electrodes, FeS positive electrodes, and a molten salt electrolyte. In the early work, the molten salt was the LiCl-KCl eutectic (58.2 mol % LiCl-41.8 mol % KCl), but in recent work various electrolyte compositions have been used, i.e., LiCl-rich LiCl--KCl (typically 67 mole % LiCl), LiF-LiCl-KCl, or LiF-LiCl-LiBr (1). The use of these electrolytes requires cell operating temperatures in the range of 703-773 K. As these cells are cycled, it has been shown that, when LiCl-KCl electrolytes were used, local electrolyte compositional changes occurred because of ion transport processes and chemical reactions in the cells. However, despite the temperature or the nature of the electrolyte, iron and lithium sulfide are the final discharge products. Thus, a systematic investigation of the solubility of Li/sub 2/S in a variety of electrolytes containing LiCl as a function of temperature is of technological importance in the development of these cells. We report new solubility measurements of Li/sub 2/S in the LiF-LiCl--LiBr eutectic solution (22 mol %-31 mol %-47 mol %) at 739 and 773 K. The observed increase of Li/sub 2/S solubility as the solvent is changed from LiCl-KCl to LiF-LiCl-LiBr and then to LiF-LiCl is explained in terms of known molten salt theories.

  18. Probing the transition state with negative ion photodetachment: The Cl + HCl and Br + HBr reactions

    SciTech Connect

    Metz, R.B.; Weaver, A.; Bradforth, S.E.; Kitsopoulos, T.N.; Deumark, D.M. )

    1990-02-22

    The transition-state region for neutral hydrogen-transfer reactions can be probed by photodetaching the appropriate stable, hydrogen-bonded negative ion. This paper presents a detailed account of this method, in which the Cl + HCl and Br + HBr reactions are investigated by photoelectron spectroscopy of ClHCl{sup {minus}}, BrHBr{sup {minus}}, and the corresponding deuterated species. The photoelectron spectra exhibit resolved vibrational structure attributed to the unstable neutral (ClHCl) or (BrHBr) complex. The BrHBr{sup {minus}} and BrDBr{sup {minus}} spectra exhibit narrow (15-20 meV) peaks that are likely to result from reactive resonance states supported by the Br + HBr potential energy surface, as well as peaks that appear to be from an electronically excited state of the (BrHBr) complex. The BrHBr{sup {minus}} and BrDBr{sup {minus}} results have been analyzed to yield an effective collinear potential energy surface for the Br + HBr reaction.

  19. Fractionation of Cl/Br during fluid phase separation in magmatic-hydrothermal fluids

    NASA Astrophysics Data System (ADS)

    Seo, Jung Hun; Zajacz, Zoltán

    2016-06-01

    Brine and vapor inclusions were synthesized to study Cl/Br fractionation during magmatic-hydrothermal fluid phase separation at 900 °C and pressures of 90, 120, and 150 MPa in Li/Na/K halide salt-H2O systems. Laser ablation ICP-MS microanalysis of high-density brine inclusions show an elevated Cl/Br ratio compared to the coexisting low-density vapor inclusions. The degree of Cl/Br fractionation between vapor and brine is significantly dependent on the identity of the alkali metal in the system: stronger vapor partitioning of Br occurs in the Li halide-H2O system compared to the systems of K and Na halide-H2O. The effect of the identity of alkali-metals in the system is stronger compared to the effect of vapor-brine density contrast. We infer that competition between alkali-halide and alkali-OH complexes in high-temperature fluids might cause the Cl/Br fractionation, consistent with the observed molar imbalances of alkali metals compared to halides in the analyzed brine inclusions. Our experiments show that the identity of alkali metals controls the degrees of Cl/Br fractionation between the separating aqueous fluid phases at 900 °C, and suggest that a significant variability in the Cl/Br ratios of magmatic fluids can arise in Li-rich systems.

  20. Origin of halides (Cl- and Br-) and of their stable isotopes (d37Cl and d81Br) at the Tournemire URL (France) - Experimental and numerical approach

    NASA Astrophysics Data System (ADS)

    Bachir-Bey, Nassim; Matray, Jean-Michel

    2014-05-01

    This work is part of research conducted by the Institute of Radiological and Nuclear Safety (IRSN) on the geological disposal of High-Level and Intermediate-Level Long-Lived (HL-ILLL) radioactive waste in deep clayrocks. In France, the choice of the potential host rock for the geological storage is focused on the Callovian-Oxfordian (COx) of Meuse/Haute-Marne from its low permeability, capacity for self- sealing, high sorption and ability to radionuclide (RN) transport by diffusion. IRSN, which plays an expert role for ASN has its own underground research laboratory in a clayrock which has strong analogies to the COx. This is the Toarcian/Domerian clayrock located at Tournemire in southern Aveyron in France. The purpose of this study was to assess the transfer of RN in the Tournemire clayrock through the study of halides contents and of their stable isotopes (Cl-, Br-, Cl-/Br-, d37Cl, d81Br). The approach used was multiple and consisted for halides to: 1) Assess their stock in different fractions of the rock by applying several techniques including i) alkaline fusion for their total stock, ii) leaching to access their stock in porewater and to mineral phases sensitive to dissolution iii) cubic diffusion for their stock in porewater, 2) Get their diffusive transport parameters of a selection of samples from the upper Toarcian by cubic diffusion experiments modelled using the Hytec transport code developed by Mines ParisTech and 3) Model their transport after palaeohydrogeological known changes of the Tournemire massif. The experimental approach, conducted at the LAME lab, did not lead to an operational protocol for the alkaline fusion due to an incomplete rock dissolution. Leaching was used to characterize the concentrations of halides in the fractions of pore water and of minerals sensitive to dissolution. The results show levels of halides much higher than those of pore water with very low Cl/Br ratios likely resulting from the dissolution of mineral species. The

  1. Al/Cl2 molten salt battery

    NASA Technical Reports Server (NTRS)

    Giner, J.

    1972-01-01

    Molten salt battery has been developed with theoretical energy density of 5.2 j/kg (650 W-h/lb). Battery, which operates at 150 C, can be used in primary mode or as rechargeable battery. Battery has aluminum anode and chlorine cathode. Electrolyte is mixture of AlCl3, NaCl, and some alkali metal halide such as KCl.

  2. Geochemistry of the Halogens (I, Br, Cl) and Evolution of the Seawater During the Archean

    NASA Astrophysics Data System (ADS)

    Avice, G.; Marty, B.; Burgess, R.; Goldsmith, S. L.

    2015-12-01

    Halogens (I, Cl, Br) on Earth are depleted relative to the results of the condensation sequence of elements from the solar nebula [1]. The cause of this depletion remains unknown but might be related to loss from impacts or to the presence of an hidden reservoir (e.g. core). The presence of fluid inclusions in hydrothermal quartz of various ages is an opportunity to follow the evolution of the composition of the atmosphere (N, noble gases) through time [2] but also of halogens in seawater (their main reservoir). Such studies may help to constrain what is the origin of these volatile elements on Earth. For this purpose, we analysed quartz from hydrothermal veins and pods of various localities and ages (e.g. Barberton Greenstone Belt (South Africa; 3.2 Ga), Fortescue Group (Australia; 2.7 Ga)) by crushing and step-heating following the extended Ar-Ar method [3]. In Barberton and Fortescue Gp. quartz, a hydrothermal component characterized by excess 40Ar (40ArE) and closely associated with chlorine is clearly identified from crushing and step-heating results and permits to define a 40ArE/Cl used to correct Ar-Ar data for this contribution. In the case of Barberton, the correction for the hydrothermal component leads to an approximate formation age of the quartz of 3.2 (+/- 0.1) Ga. In Barberton quartz, halogens elemental ratios obtained during crushing and step-heating experiments are highly enriched in iodine and bromine (I/Cl=2-7x10-4; Br/Cl=4-10x10-3) relative to modern seawater. These results are similar to those found in a previous study of Barberton fluid inclusions [3] and can be interpreted as indicators that organic carbon was not sufficiently abundant at this time and/or this location to efficiently pump Br and I during sediment burial. Iodine and bromine, in Fortescue Gp. quartz, are less enriched suggesting that, in that case, organic activity already acted as pump for these elements. [1] Sharp & Draper (2013) EPSL, 369-370, p. 71-77 [2] Pujol et al. (2011

  3. Effect of halogen (Cl, Br) on the symmetry of flexible perovskite-related framework.

    PubMed

    Bai, Chunyan; Yu, Hongwei; Han, Shujuan; Pan, Shilie; Zhang, Bingbing; Wang, Ying; Wu, Hongping; Yang, Zhihua

    2014-10-20

    The perovskite structure is a good candidate for the design of functional materials. On the basis of the combination of B6O13 groups and XM6 (X = Cl, Br; M = alkali metals) octahedra, three new perovskite-related crystals Na3B6O10Cl, RbNa2B6O10Cl, and RbNa2B6O10Br have been synthesized by a high-temperature solution method for the first time. Na3B6O10Cl and RbNa2B6O10Cl are isostructural and crystallize in the noncentrosymmetric (NCS) space group P212121 (No. 19), while RbNa2B6O10Br belongs to the centrosymmetric (CS) space group Pnma (No. 62). The phenomenon that Cl-containing borates are not isostructural with corresponding Br-containing borates is extremely rare among borates. Detailed structure analysis suggests that the difference is owing to the effect of the halogen (Cl, Br) on the symmetry of the flexible perovskite-related framework. In addition, thermal analyses, IR spectroscopy, the UV-vis-NIR diffuse reflectance spectrum, and first-principles theoretical studies have also been performed on the three compounds.

  4. Br-Cl-Na systematics in Illinois basin fluids: Constraints on fluid origin and evolution

    SciTech Connect

    Walter, L.M.; Huston, T.J. ); Stueber, A.M. )

    1990-04-01

    The authors present here bromide, chloride, and sodium data for fluids from reservoirs of Ordovician through Pennsylvania age in the Illinois basic which suggest that remnant marine fluids contribute significantly to fluid Cl budgets. Cl/Br and NaBr ratios for Ordovician through Devonian formation fluids are relatively uniform and near those for seawater, despite greater than a factor of ten range in Cl concentration. In contrast, fluids from Mississippian and Pennsylvanian reservoirs, separated from older reservoirs by the New Albany Shale Group, have more variable fluid Cl/Br and Na/Br ratios, most of which are significantly greater then those of seawater. The 1:1 stoichiometry of Cl and Na increases for Mississippian and Pennsylvanian formation fluids is consistent with halite dissolution. Nevertheless, Br systematics and mass-balance considerations indicate that he overall Cl budget of Illinois basin formation fluids appears to be more significantly influenced by the contribution from subaerially evaporated seawater than by halite dissolution.

  5. Optical properties and electronic structure of BiTeCl and BiTeBr compounds

    NASA Astrophysics Data System (ADS)

    Makhnev, A. A.; Nomerovannaya, L. V.; Kuznetsova, T. V.; Tereshchenko, O. E.; Kokh, K. A.

    2016-09-01

    Optical properties of BiTeCl and BiTeBr compounds with a strong Rashba spin-orbit coupling are studied in the 0.08-5.0 eV range using the optical ellipsometry method. Fundamental characteristics of the electronic structure are obtained. Similarly to BiTeI, spectra of the imaginary part of dielectric permittivity constant ɛ2( E) in the energy interval between the plasma edge and the threshold of an intense interband absorption (0.7 eV in BiTeCl and 0.6 eV in BiTeBr) display a fine structure of electronic transitions at 0.25 and 0.55 eV in BiTeCl and 0.20 and 0.50 eV in BiTeBr. These features are assigned to electronic transitions between the bulk conduction zones split by the Rashba spin-orbit interaction. The parameters of the electronic structure of BiTeCl and BiTeBr are compared with the BiTeI compound that was studied earlier. In the BiTeCl-BiTeBr-BiTeI row, the absorption edge and main features of the fundamental absorption exhibit a shift to low energies.

  6. Reaction and deactivation of HCl(v=1,2) by Cl, Br, and H atoms

    NASA Astrophysics Data System (ADS)

    Macdonald, R. G.; Moore, C. Bradley

    1980-08-01

    Total decay rates for HCl(v=2, 1) were measured in the range 294-439 K for Cl, 295-390 K for Br, and at 296 K for H. HCl(v=2) was produced directly by pulsed laser excitation of the overtone. The fraction of HCl(v=2) relaxed to HCl(v=1) was determined. For HCl(v=2) + Cl, relaxation gave entirely HCl(v=1) within an experimental uncertainty of ±10%, the total relaxation rate was large, k/v¯?5 Å2, and rates varied only slightly with temperature. For Br+HCl(v=2) reaction to HBr(v=0) + Cl is exoergic by about kT. Relaxation to HCl(v=1) is the dominant process. Reaction contributes roughly 17% and 34% to the loss of HCl(v=2) at 295 and 390 K, respectively. In contrast to the result for Br and for O(reported previously), H+HCl(v=2) gives 65% H2+Cl and only 35% HCl(v=1)+H. For HCl(v=1)+H, Cl, O the vibrational excitation energy is greater than the activation energy for reaction. The relaxation rates are between 1/2 and 1/3 of the A values for the measured thermal exchange rates A exp(-ΔEact/RT). For HCl(v=1)+Br, well below threshold, the rate is some 20 times less than for HCl(v=1)+Cl. The rate for HCl(v=2)+Br, just above reaction threshold is not dramatically larger. The ratios of vibrational relaxation rates for HCl(v=2) vs HCl(v=1) are 5.0±1.3, 4.2±0.4, and 5.0±1.3 for O, Cl, and Br, respectively. Any first order linear perturbation treatment gives rates proportional to v; the data scale more closely as v2.

  7. In situ observations of midlatitude stratospheric ClO and BrO

    NASA Astrophysics Data System (ADS)

    Brune, William H.; Anderson, James C.

    1986-12-01

    A balloon-borne experiment to measure midlatitude stratospheric BrO and ClO concentrations by NO chemical conversion/atomic resonance fluorescence was flown from Palestine, Texas, on May 20 1986. In this first study of BrO, no signal attributable to BrO was detected, and upper limits (2 sigma uncertainty) between 35 and 24 km altitude give BrO mixing ratios less than 15 pptv. Current models predict mixing ratios that are 1.7 times larger. Measurements of ClO were obtained at less than 0.2-km altitude resolution from 41 to 22 km. The smoothly varying altitude profile lies within the range of two-dimensional model calculations.

  8. The superacid HBr/AlBr(3) : protonation of benzene and ordered crystal structure of [C(6)H(7)](+)[Al(2)Br(7)](-).

    PubMed

    Scholz, Franziska; Himmel, Daniel; Eisele, Lea; Unkrig, Wiebke; Krossing, Ingo

    2014-02-03

    Crystalline and properly ordered protonated benzene as the [C6 H7 ](+) [Al2 Br7 ](-) ⋅(C6 H6 ) salt 1 are obtained by the combination of solid AlBr3 , benzene, and HBr gas. Compound 1 was characterized and verified by NMR, Raman and X-Ray spectroscopy. This unexpected simple and straight forward access shows that HBr/AlBr3 is an underestimated superacid that should be used more frequently.

  9. Observations of Cl2, Br2, and I2 in Coastal Urban Air

    NASA Astrophysics Data System (ADS)

    Finley, B. D.; Saltzman, E. S.

    2006-12-01

    Halogen radicals can both produce and destroy ozone in urban air, but there are few direct measurements of reactive halogens and their precursors. This study reports observations of the dihalogens Cl2, Br2, and I2 at a coastal urban site using negative ion atmospheric pressure chemical ionization tandem mass spectrometry. Measurements were made from the Scripps pier, 10 m above the sea surface, from January 1 to January 29, 2006. These are the first measurements of Br2 at a coastal urban site and the first measurements of I2 using triple quadrupole mass spectrometry. Fifteen minute average mixing ratios ranged from below the detection limit of 3 ppt to 28 ppt for Cl2, 20 ppt for Br2, and 11 ppt for I2. Cl2 exhibited a strong diurnal variability, with higher Cl2 levels during the day and lower Cl2 levels at night, suggesting a photochemical production mechanism. I2 also showed a consistent diurnal pattern, exceeding detection limits only during nighttime. I2 was associated with air flow over nearby coastal kelp beds. Br2 was detectable both day and night and did not exhibit a consistent diurnal pattern. The Cl2 levels observed in this study imply significant (> 10 ppb/day) ozone production due to oxidation of hydrocarbons by chlorine atoms. The Br2 levels observed suggest that catalytic destruction of ozone by bromine radicals may also be significant (> 8 ppb/day) in polluted coastal regions. The observed I2 levels imply that iodine radicals do not have a significant impact on ozone levels, accounting for < 1 ppb/day ozone destruction.

  10. BiTeCl and BiTeBr: A comparative high-pressure optical study

    NASA Astrophysics Data System (ADS)

    Crassee, I.; Borondics, F.; Tran, M. K.; Autès, G.; Magrez, A.; Bugnon, P.; Berger, H.; Teyssier, J.; Yazyev, O. V.; Orlita, M.; Akrap, A.

    2017-01-01

    We here report a detailed high-pressure infrared transmission study of BiTeCl and BiTeBr. We follow the evolution of two band transitions: the optical excitation β between two Rashba-split conduction bands, and the absorption γ across the band gap. In the low-pressure range, p <4 GPa, for both compounds β is approximately constant with pressure and γ decreases, in agreement with band structure calculations. In BiTeCl, a clear pressure-induced phase transition at 6 GPa leads to a different ground state. For BiTeBr, the pressure evolution is more subtle, and we discuss the possibility of closing and reopening of the band gap. Our data is consistent with a potential Weyl phase in BiTeBr at 5 -6 GPa, followed by the onset of a structural phase transition above 7 GPa.

  11. Cl2 Measurements in Polluted Coastal Air Using a Br- Addition CIMS Technique

    NASA Astrophysics Data System (ADS)

    Lawler, M. J.; Saltzman, E. S.

    2008-12-01

    Molecular chlorine (Cl2) was measured in ambient air using chemical ionization mass spectrometry (CIMS) with Br- as a reagent ion. Ionization was carried out by adding CHBr3 to ambient air and flowing the gas mixture through a 63Ni ion source maintained at 300 Torr. The resulting Cl2Br- adduct was collisionally dissociated in a triple quadrupole mass spectrometer and detected as Cl-. Ambient Cl2 measurements were made at Irvine, CA, from August 1-8, 2008. Air was drawn to the instrument from outside via a ~4m long laminar flow inlet. Inlet and instrument blanks were assessed by passing ambient air through carbonate-coated glass wool, and the instrument was calibrated with a Cl2 permeation tube. During this study, the mean detection limit for Cl2 was estimated at approximately 2 ppt. Cl2 showed a diel cycle on the days it was detectable, with nighttime mixing ratios up to about 15 ppt and daytime values of a few ppt or less. A rapid decrease in Cl2 in surface air was observed overnight in association with stagnation of the nocturnal surface layer.

  12. Rechargeable Al/Cl2 battery with molten AlCl4/-/ electrolyte.

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.; Giner, J.; Burrows, B.

    1972-01-01

    A molten salt system based on Al- and Cl2 carbon electrodes, with an AlCl3 alkali chloride eutectic as electrolyte, offers promise as a rechargeable, high energy density battery which can operate at a relatively low temperature. Electrode kinetic studies showed that the electrode reactions at the Al anode were rapid and that the observed passivation phenomena were due to the formation at the electrode surface of a solid salt layer resulting from concentration changes on anodic or cathodic current flow. It was established that carbon electrodes were intrinsically active for chlorine reduction in AlCl3-alkali chloride melts. By means of a rotating vitreous carbon disk electrode, the kinetic parameters were determined.

  13. Proposed method of hydrogeochemical exploration for salt deposits using ClBr ratios, Eastern Province, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Smith, C.L.

    1991-01-01

    Despite the value of the salt (NaCl) and brine used by the chemical industry, geochemical prospecting techniques are not customarily employed in the search for these raw materials. In this study, Br geochemistry is used as the basis for a proposed hydrogeochemical prospecting technique that was designed to search for shallow halite beds in the Eastern Province of the Kingdom of Saudi Arabia. Near-surface brine samples were collected at Sabkhah Jayb Uwayyid, both directly above and distant from a buried salt bed. Brine samples collected both directly above and offset to the north-west of the salt bed had ClBr ratios > 8000. The regional background ClBr ratio of fresh nonmarime ground water is ???300. The large range in ClBr ratios and the association of high ClBr ratios with the buried salt body suggest that the ratio can be useful in hydrogeochemical prospecting for sibakh-associated, shallow salt bodies. ?? 1991.

  14. Environmentally friendly microwave ionic liquids synthesis of hybrids from cellulose and AgX (X=Cl, Br).

    PubMed

    Dong, Yan-Yan; He, Jing; Sun, Shao-Long; Ma, Ming-Guo; Fu, Lian-Hua; Sun, Run-Cang

    2013-10-15

    The purpose of this article was to explore an environmentally friendly strategy to synthesis of biomass-based hybrids. Herein, microwave-assisted ionic liquids method was applied to fabricate the hybrids from cellulose and AgX (X=Cl, Br) using cellulose and AgNO3. The ionic liquids act simultaneously as a solvent, a microwave absorber, and a reactant. Ionic liquids provided Cl(-) or Br(-) to the synthesis of AgCl or AgBr crystals; thus no additional reactant is needed. The products are characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The cellulose-Ag/AgCl hybrid and cellulose-Ag/AgBr hybrid were also obtained by using cellulose-AgCl and cellulose-AgBr hybrids as precursors. This environmentally friendly microwave-assisted ionic liquids method is beneficial to the hybrids with high dispersion.

  15. Engineering BiOX (X = Cl, Br, I) nanostructures for highly efficient photocatalytic applications

    NASA Astrophysics Data System (ADS)

    Cheng, Hefeng; Huang, Baibiao; Dai, Ying

    2014-01-01

    Heterogeneous photocatalysis that employs photo-excited semiconductor materials to reduce water and oxidize toxic pollutants upon solar light irradiation holds great prospects for renewable energy substitutes and environmental protection. To utilize solar light effectively, the quest for highly active photocatalysts working under visible light has always been the research focus. Layered BiOX (X = Cl, Br, I) are a kind of newly exploited efficient photocatalysts, and their light response can be tuned from UV to visible light range. The properties of semiconductors are dependent on their morphologies and compositions as well as structures, and this also offers the guidelines for design of highly-efficient photocatalysts. In this review, recent advances and emerging strategies in tailoring BiOX (X = Cl, Br, I) nanostructures to boost their photocatalytic properties are surveyed.

  16. Thermodynamic Properties of Compressed CuX (X = Cl, Br) Compounds: Ab Initio Study

    NASA Astrophysics Data System (ADS)

    Bioud, Nadhira; Kassali, Kamel; Bouarissa, Nadir

    2017-04-01

    A pseudopotential plane wave method based on the density functional theory has been employed to study some thermodynamic properties of copper chloride (CuCl) and copper bromide (CuBr) compounds under the effect of temperature and pressure. The phase transition pressure, the unit cell volume, the isothermal bulk modulus, the constant volume heat capacity, the entropy, the Debye temperature, the Grüneisen parameter and the volumetric thermal expansion coefficient are studied in the pressure range 0-10 GPa, and for temperatures ranging from 0 K up to 650 K and 750 K for CuCl and CuBr, respectively. The phase transition pressure is found to be around 7.8 and 6.95 GPa for CuCI and CuBr, respectively. These values are respectively in reasonably good agreement with the experimental ones of 8.2 GPa and 6.8 GPa reported in the literature. Moreover, at room temperature and zero pressure, the heat capacity at constant volume and the Grüneisen parameter of both compounds of interest are found to be in good agreement with the available experimental and theoretical data. The information gathered from the present investigation may be useful for the study of the behavior of the fundamental properties of CuCI and CuBr under the influence of high temperature and pressure.

  17. Kinetics of the BrO + ClO reaction and implications for stratospheric ozone

    NASA Technical Reports Server (NTRS)

    Hills, Alan J.; Cicerone, Ralph J.; Calvert, Jack G.; Birks, John W.

    1987-01-01

    The first direct measurements of the rate constant and product distribution of the BrO + ClO reaction as a function of temperature is reported. It is shown that this reaction could account for a large fraction of the springtime ozone depletion over Antarctica and provide a source of chlorine dioxide of sufficient magnitude to explain the recent measurements of this species in the Antarctic atmosphere, provided that the stratosphere contains a sufficient quantity of bromine.

  18. Magnetism of CuX2 frustrated chains (X = F, Cl, Br): Role of covalency

    NASA Astrophysics Data System (ADS)

    Lebernegg, S.; Schmitt, M.; Tsirlin, A. A.; Janson, O.; Rosner, H.

    2013-04-01

    Periodic and cluster density functional theory (DFT) calculations, including DFT+U and hybrid functionals, are applied to study magnetostructural correlations in spin-(1)/(2) frustrated chain compounds CuX2: CuCl2, CuBr2, and a fictitious chain structure of CuF2. The nearest-neighbor and second-neighbor exchange integrals J1 and J2 are evaluated as a function of the Cu-X-Cu bridging angle θ in the physically relevant range 80∘-110∘. In the ionic CuF2, J1 is ferromagnetic for θ≤100∘. For larger angles, the antiferromagnetic superexchange contribution becomes dominant, in accord with the Goodenough-Kanamori-Anderson rules. However, both CuCl2 and CuBr2 feature ferromagnetic J1 in the whole angular range studied. This surprising behavior is ascribed to the increased covalency in the Cl and Br compounds, which amplifies the contribution from Hund's exchange on the ligand atoms and renders J1 ferromagnetic. At the same time, the larger spatial extent of X orbitals enhances the antiferromagnetic J2, which is realized via the long-range Cu-X-X-Cu paths. Both periodic and cluster approaches supply a consistent description of the magnetic behavior which is in good agreement with the experimental data for CuCl2 and CuBr2. Thus, owing to their simplicity, cluster calculations have excellent potential to study magnetic correlations in more involved spin lattices, and facilitate application of quantum-chemical methods.

  19. Measurements of ClO and BrO in Support of the SESAME Campaign

    NASA Technical Reports Server (NTRS)

    Toohey, Darin W.

    1996-01-01

    A Final Report of a project to measure ClO and BrO from scientific balloons launched during the Second European Stratospheric Arctic and Midlatitude Expedition (SESAME) is presented. A successful launch was initiated on February 3, 1995 in Kiruna, Sweden. A second launch on March 6, 1995 resulted in the retrieval of a partial altitude profile of these species, and a full engineering characterization of a new instrument designed for lightweight balloons.

  20. Laser cooling of MgCl and MgBr in theoretical approach

    SciTech Connect

    Wan, Mingjie; Shao, Juxiang; Huang, Duohui; Yang, Junsheng; Cao, Qilong; Jin, Chengguo; Wang, Fanhou; Gao, Yufeng

    2015-07-14

    Ab initio calculations for three low-lying electronic states (X{sup 2}Σ{sup +}, A{sup 2}Π, and 2{sup 2}Π) of MgCl and MgBr molecules, including spin-orbit coupling, are performed using multi-reference configuration interaction plus Davidson correction method. The calculations involve all-electronic basis sets and Douglas–Kroll scalar relativistic correction. Spectroscopic parameters well agree with available theoretical and experimental data. Highly diagonally distributed Franck-Condon factors f{sub 00} for A{sup 2}Π{sub 3/2,1/2} (υ′ = 0) → X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) are determined for both MgCl and MgBr molecules. Suitable radiative lifetimes τ of A{sup 2}Π{sub 3/2,1/2} (υ′ = 0) states for rapid laser cooling are also obtained. The proposed laser drives A{sup 2}Π{sub 3/2} (υ′ = 0) → X{sup 2}Σ{sup +}{sub 1/2} (υ″ = 0) transition by using three wavelengths (main pump laser λ{sub 00}; two repumping lasers λ{sub 10} and λ{sub 21}). These results indicate the probability of laser cooling MgCl and MgBr molecules.

  1. Mutual neutralization of He+ with the anions Cl-, Br-, I-, and SF6-

    NASA Astrophysics Data System (ADS)

    Wiens, Justin P.; Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, Albert A.

    2016-05-01

    Mutual neutralization (MN) rate coefficients kMN for He+ with the anions Cl-, Br-, I-, and SF6- are reported from 300 to 500 K. The measured rate coefficients may contain a contribution from transfer ionization, i.e., double ionization of the anion. The large rate coefficient for He+ + SF6- (2.4 × 10-7 cm3 s-1 at 300 K) is consistent with earlier polyatomic MN results found to have a reduced mass dependence of μ-1/2. Neutralization of He+ by the atomic halides follows the trend observed earlier for Ne+, Ar+, Kr+, and Xe+ neutralized by atomic halides, kMN (Cl-) < kMN (Br-) < kMN (I-). Only an upper limit could be measured for the neutralization of He+ by Cl-. Predictions of the rate coefficients from a previously proposed simple model of atomic-atomic MN results are consistent with the present He+-halide rate coefficients. The temperature dependences are modestly negative for Br- and I-, while that for SF6- is small or negligible.

  2. In-situ Cl/Br measurements in scapolite and fluid inclusions by LA-ICP-MS: A powerful tool to constrain fluid sources

    NASA Astrophysics Data System (ADS)

    Hammerli, J.; Rusk, B.; Spandler, C.; Oliver, N. H. S.; Emsbo, P.

    2012-04-01

    Chlorine and bromine are highly conservative elements, and are therefore widely used to trace the origin of fluids in sedimentary and hydrothermal/magmatic systems (e.g. Hanor & McIntosh, 2007; Nahnybida et al., 2009). Halogens are important ligands for metal transport in hydrothermal solutions and thus their behavior in hydrothermal environments is crucial for comprehending ore-forming processes. Besides fluid inclusions, scapolite-group minerals hold great potential as a tracer of igneous, metamorphic, and hydrothermal processes, as no Cl/Br fractionation in scapolite has been observed and therefore halogen ratios in scapolite are thought to mirror the halogen ratios in coexisting melts and fluids (Pan & Dong, 2003). Hence, Cl/Br ratios in fluid inclusions and minerals can be utilized to trace the origin of fluids and fluid-rock interaction pathways. Due to their high ionization energies, bromine and chlorine are not routinely measured by LA-ICP-MS and suitable standards are rare. Little is known about the potential interferences and analytical limitations of in-situ chlorine and bromine analysis by LA-ICP-MS. Nevertheless, Seo et al. (2011) showed that quantification of Br and Cl in single synthetic and natural fluid inclusions is possible. In this study, we have analyzed several scapolite grains of known bromine and chlorine concentrations by LA-ICP-MS and assess the capabilities and limitations of this method. The results show that Cl/Br ratios measured by LA-ICP-MS closely reproduce known values determined by microprobe (Cl), the Noble Gas Method (Br) and INAA (Br) (Kendrick, 2011; Lieftink et al., 1993) using laser ablation spot sizes from 24-120 μm. The well-characterized scapolite grains cover bromine concentrations from 50-883 ppm and chlorine concentrations from 3 to 4 wt.%. In order to further assess the method, we analyzed Cl/Br ratios in natural fluid inclusions hosted in sphalerite that were previously characterized by crush and leach ion

  3. The First Simultaneous Airborne Measurements of BrO, BrCl HOBr in the Tropics: An Assessment on the HOx Budget and O3 Depletion

    NASA Astrophysics Data System (ADS)

    Le Breton, M. R.; Gallagher, M. W.; Shallcross, D. E.; Evans, M. J.; Carpenter, L.; Andrews, S.; Lidster, R. T.; Harris, N. R. P.; Percival, C.

    2014-12-01

    This study represents the first simultaneous airborne measurements of BrO, BrCl, Br2 and HOBr in the tropics using a chemical ionisation mass spectrometer (CIMS). The results suggest that inorganic halogen chemistry has a more significant impact on O3 depletion and oxidising capacity of the troposphere than previously thought. The CIMS instrument was operated on-board the BAe-146 FAAM research aircraft across 20 flights, as part of the CAST (Coordinated Airborne Studies in the Tropics) campaign based on Guam, Micronesia and was supported by measurements of O3 and NOx from core instruments and bromocarbons from Whole Air Samples (WAS). The mean tropospheric BrO concentration over 20 flights was calculated to be 0.69 ppt; a factor of 4 times greater than that predicted by GEOS-Chem running with a tropospheric bromine simulation. An underestimation of HOBr, Br2 and BrCl in the model, when compared to the CIMS data, will contribute to this discrepancy, thus increasing the availability of atomic Br through photolysis, however this does not compensate for the bias currently observed. The magnitude of this discrepancy and subsequent effect on O3 depletion in the tropics is assessed and possible mechanisms are proposed. The measurements of these halogenated species are further used to assess their impact on the HOx budget in the tropics via steady state estimations.

  4. Fundamental reflectivity and electronic structure of NiBr2 and NiCl2 insulators

    NASA Astrophysics Data System (ADS)

    Pollini, I.; Thomas, J.; Jezequel, G.; Lemonnier, J. C.; Mamy, R.

    1983-01-01

    The fundamental reflectivity of NiBr2 and NiCl2 has been measured over the energy range 2-11 eV from 300 to 30 K with the use of synchrotron radiation. The imaginary part of the dielectric constant ɛ2 has been determined at 30 K by means of the Kramers-Kronig technique. The structure in the complex optical spectra of nickel halides is interpreted in terms of charge-transfer transitions, orbital promotions, excitons, and direct allowed interband transitions at the symmetry points Γ, Z, and F, and along symmetry lines Λ, B, and Γ-L of the Brillouin zone. The energy gap is assigned to Γ-3-->Γ+1 transitions at the zone center, both in NiBr2 (7.90 eV) and NiCl2 (8.70 eV). Finally, the interpretation of the satellite exciton at 6.5 eV in NiBr2 (30 K) is discussed.

  5. Investigating the properties of infrared PCFs based on AgCl-AgBr, AgBr-TlI, AgCl-AgBr-AgI(TlI) crystals theoretically and experimentally

    NASA Astrophysics Data System (ADS)

    Korsakov, A. S.; Zhukova, L. V.; Vrublevsky, D. S.; Korsakova, E. A.

    2014-12-01

    For operating at the CO2 laser wavelength (10.6 μm), we manufactured single- and double-layered infrared (IR) fibers, as well as those with an enlarged mode field diameter, obtained via extrusion from Ag(Cl) x Br1 - x (0 < x < 1), Ag1 - x Tl x Br1 - x I x (0 < x ≤ 0.08), Ag1 - x Tl x Cl y I z Br1 - y - z (0.003 ≤ x ≤ 0.040; 0.066 ≤ y ≤ 0.246; 0.004 ≤ z ≤ 0.048) crystals. We calculated their fundamental characteristics at 10.6 μm and conducted computer simulation of their structure and mode field beforehand. Optical and mechanical characteristics of IR crystals and fibers, such as transmission range, refractive indices, and durability, were also determined, with the dependence of varying monadic thallium iodide content on them being shown as well. In particular, we demonstrated that the increase of thallium iodide content in the initial silver chloride bromide widens the transparency range to 40 μm and improves the rupture strength up to 200 MPa, which is due to the decrease in average fiber grain size up to 95 nm—nanocrystalline size. Using a CCD camera for the far field investigation at 10.6 μm, we showed the single mode of the fibers obtained.

  6. Kinetics and product studies of the BrO + ClO reaction - Implications for Antarctic chemistry

    NASA Astrophysics Data System (ADS)

    Sander, Stanley P.; Friedl, Randall R.

    1988-08-01

    Discharge flow-mass spectrometry and flash photolysis-UV spectrometry were used to investigate the reaction of ClO with BrO over the temperature range of 220-400 K and the pressure range of 1-760 Torr. Rate constants were determined for: (1) Br + ClOO, (2) Br + OClO, and (3) BrCl + O2. It is found that the rate constants for the overall reaction and each reaction branch are inversely dependent on temperature and independent of pressure. For temperatures found in the Antarctic stratosphere, the rate coefficients for the channels yielding ClOO and OClO are a factor of 2-3 larger than previously estimated.

  7. Kinetics and product studies of the BrO + ClO reaction - Implications for Antarctic chemistry

    NASA Technical Reports Server (NTRS)

    Sander, Stanley P.; Friedl, Randall R.

    1988-01-01

    Discharge flow-mass spectrometry and flash photolysis-UV spectrometry were used to investigate the reaction of ClO with BrO over the temperature range of 220-400 K and the pressure range of 1-760 Torr. Rate constants were determined for: (1) Br + ClOO, (2) Br + OClO, and (3) BrCl + O2. It is found that the rate constants for the overall reaction and each reaction branch are inversely dependent on temperature and independent of pressure. For temperatures found in the Antarctic stratosphere, the rate coefficients for the channels yielding ClOO and OClO are a factor of 2-3 larger than previously estimated.

  8. High-resolution continuum source electrothermal absorption spectrometry of AlBr and CaBr for the determination of bromine

    NASA Astrophysics Data System (ADS)

    Huang, Mao Dong; Becker-Ross, Helmut; Florek, Stefan; Heitmann, Uwe; Okruss, Michael

    2008-05-01

    Molecular absorption spectra of AlBr and CaBr, produced in a graphite furnace, were investigated using a high-resolution echelle spectrometer equipped with a xenon short-arc lamp as continuum source. The analytical usability of the spectra for the determination of bromine was studied. To this end, the molecular absorptions of AlBr at 278.914 nm and CaBr at 625.315 nm were evaluated. Apart from strong absorption bands of CaF around 625.3 nm, which disturb the use of CaBr, no spectral interferences were observed for both AlBr and CaBr. Regarding chemical interference with matrix substances, the molecular absorption of AlBr and CaBr is influenced in a different way. While the sensitivity of the CaBr absorption is susceptible to chloride, aluminum, potassium and sodium ions, there is no significant effect on the AlBr absorption. In contrast, the inorganic acids (nitric, phosphoric, and sulfuric) have an influence on AlBr, but not on the CaBr molecular absorption. Therefore, the two methods complement each other and each has its own application area. Regarding real samples, a salt sample from the death sea and an organic pharmaceutical were evaluated. The results were in good agreement with those derived from two independent methods and with an existing reference value. Relative standard deviations were found in the range of 5%. The limit of detection for bromine was about 2 ng for both AlBr and CaBr molecular absorption; the dynamic range was linear at least up to 250 ng Br.

  9. Synthesis and structure of fullerene halides C{sub 70}X{sub 10} (X = Br, Cl) and C{sub 78}Cl{sub 18}

    SciTech Connect

    Burtsev, A. V.; Kemnitz, E.; Troyanov, S. I.

    2008-07-15

    The crystal and molecular structures of the fullerene halides C{sub 70}Br{sub 10} . 3C{sub 6}H{sub 2}Cl{sub 4}, C{sub 70}Cl{sub 8.4}Br{sub 1.6}, and C{sub 78}Cl{sub 18} have been determined and refined using single-crystal X-ray diffraction with synchrotron radiation. In the molecular structure of C{sub 70}X{sub 10} (X = Br, Cl), ten X halogen atoms are located in the equatorial region of the molecule and form one 1,2 and nine 1,4 contacts in C{sub 6}X{sub 2} hexagons. The structure of the higher fullerene chloride C{sub 78}Cl{sub 18} contains two isomers with symmetry C{sub 2v}, which results in the hexagonal symmetry of the crystal due to disordering.

  10. Synthesis and Screening of Thin Films in the CeCl3-CeBr3 System for Scintillator Applications

    SciTech Connect

    Matson, Dean W.; Graff, Gordon L.; Male, Jonathan L.; Johnson, Bradley R.; Nie, Zimin; Joly, Alan G.; Olsen, Larry C.

    2010-04-02

    Thin film samples of CeCl3, CeBr3, and combinatorial compositions along the CeCl3-CeBr3 join were produced using thermal evaporation, which is being evaluated as a method for rapid screening of new scintillator materials. The combinatorial thin films were shown to be compositionally reproducible from run-to-run within reasonable limitations. Analytical results suggest a continuous variation in the combinatorial samples in terms of their compositions, crystal structures, and luminescence characteristics.

  11. Source identification of nitrate in groundwater using stable isotopes and Cl/Br ratios in an agricultural area

    NASA Astrophysics Data System (ADS)

    Koh, D.; Mayer, B.

    2009-12-01

    Sources of nitrate in groundwater were investigated in an agricultural area with natural area at higher altitude, upland at hilly terrains and residential areas at low-lying lands using δ15N and δ18O of nitrate and Cl/Br ratios. The NO3- concentration in groundwater was as high as 49 mg/L, with an average of 6.0 mg/L and a median value of 4.4 mg/L as NO3-N, and, 22% of the groundwater samples exceeded the DWS of South Korea, which is 10 mg/L for NO3-N. Nitrate sources were consistently identified in residential and upland areas using stable isotopes of nitrate and Cl/Br ratios which showed that the higher δ15N-NO3- and Cl/Br ratios in residential area and lower δ15N-NO3- and Cl/Br ratios in upland Meanwhile, contribution of atmospheric nitrate in natural area was not readily observable due to resetting of δ18O-NO3- in the soil zone. The higher δ15N-NO3- values in residential area was consistent with higher Cl/Br ratios indicating the effect of domestic wastewater including sewage and septic effluents. Upland area had δ15N-NO3- corresponding to soil organic nitrogen which seems resulted from mixed sources of mineralized fertilizer and manure with higher contribution of the latter. The lower Cl/Br ratios of upland area compared to residential area indicates higher contribution of agrochemicals including fertilizers and pesticides. Statistical comparison of chemical and isotopic parameters according to land-use groups revealed that nitrate concentrations and Cl/Br ratios were distinctive between four land uses considered whereas stable isotopes of nitrate were not significantly different between anthropogenic land uses indicating Cl/Br ratio is a more efficient tracer for impact of land-uses on groundwater quality in agricultural areas.

  12. Specific oxidation pattern of soluble starch with TEMPO-NaBr-NaClO system.

    PubMed

    Hao, Jie; Lu, Jiaojiao; Xu, Naiyu; Linhardt, Robert J; Zhang, Zhenqing

    2016-08-01

    Oxidized starch, one of the most important starch derivatives, has many different properties and applications. Currently, there are two ways to produce oxidized starch, through specific and nonspecific oxidation. Specific oxidation using the stable nitroxyl radical, 2,2,6,6-tetramethyl preparidinloxy (TEMPO), with NaBr and NaClO can produce oxidized starches with different properties under good quality control. In the current study, we examine the products of specifically oxidized starch. As the amount of oxidant and the temperature, two critical factors impacting the oxidation of starch were thoroughly investigated. Analysis of the molecular weight (MW), degree of oxidization (DO) and the detailed structures of corresponding products was accomplished using gel permeation chromatography with multi-angle laser light scattering (GPC-MALLS), infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and quadrapole time-of-flight mass spectrometry (Q/TOF-MS). According to the analytical results, the oxidation patterns of starch treated with specific oxidant TEMPO-NaBr-NaClO were established. When high amounts of oxidant was applied, more glucose residues within starch were oxidized to glucuronic acids (higher DO) and substantial degradation to starch oligosaccharides was observed. By selecting a reaction temperature of 25°C a high DO could be obtained for a given amount of oxidant. The reducing end sugar residue within oxidized starch was itself oxidized and ring opened in all TEMPO-NaBr-NaClO reactions. Furthermore, extra oxidant generated additional novel structures in the reducing end residues of some products, particularly in low temperature reactions.

  13. On the growth of Hg2Cl(1-x)2Br(x2) single crystals

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Metz, E. P. A.; Stewart, A.; Gottlieb, M.; Hopkins, R.; Mazelsky, R.; Glicksman, M. E.; Haley, T. E.

    1992-01-01

    Single crystals of mixed mercurous halides Hg2X2 (where X = Cl and Br) were grown by the physical vapor transport process. Structural parameters and optical properties were determined to examine the suitability of mixed crystals for acoustooptic devices. Mixed crystals grown in the low concentration region did not show striations or banding. Crystals grown in the high concentration region showed considerable inhomogeneity in the refractive index. Since we had used identical thermal conditions, inhomogeneity was attributed to the solutal convection caused by the difference in densities of mercurous chloride and bromide vapors. A low concentration of dopant did not change the acoustic velocity of the parent components.

  14. Growth of K(Cl, Br) crystals from aqueous solutions in an X-ray field

    SciTech Connect

    Anishchik, V. M.; Val'ko, N. G. Voina, V. V.; Vorontsov, A. S.

    2008-07-15

    The influence of X-rays of different wavelength on the degree of structural quality of K(Cl, Br) crystals of mixed composition grown from aqueous solutions is considered. It is found by the methods of chemical etching, X-ray analysis, pycnometric density, and atomic-force microscopy that X-ray irradiation leads to the formation of crystals with a more perfect substructure and surface morphology and a decrease of the dislocation density and concentration of pores and cavities containing the mother liquor. It is shown that X-ray irradiation can promote preferential incorporation of less electronegative components into the crystal lattice of a solid solution.

  15. Anisotropic etching of Al by a directed Cl2 flux

    NASA Technical Reports Server (NTRS)

    Efremow, N. N.; Geis, M. W.; Mountain, R. W.; Lincoln, G. A.; Randall, J. N.

    1986-01-01

    A new Al etching technique is described that uses an ion beam from a Kaufman ion source and a directed Cl2 flux. The ion beam is used primarily to remove the native oxide and to allow the Cl2 to spontaneously react with the Al film forming volatile Al2Cl6. By controlling both the flux equivalent pressure of Cl2 and the ion beam current, this etching technique makes possible the anisotropic etching of Al with etch rates from 100 nm/min to nearly 10 microns/min with a high degree of selectivity.

  16. Magnetoelectric effects in the spiral magnets CuCl2 and CuBr2

    NASA Astrophysics Data System (ADS)

    Tolédano, P.; Ayala, A. P.; Furtado Filho, A. F. G.; do Nascimento, J. P. C.; Silva, M. A. S.; Sombra, A. S. B.

    2017-01-01

    The nature and symmetry of transition mechanisms in the spin-spiral copper halides CuCl2 and CuBr2 are analyzed theoretically. The magnetoelectric effects observed in the two multiferroic compounds are described and their phase diagram at zero and applied magnetic fields are worked out. The emergence of the electric polarization at zero field below the paramagnetic phase is shown to result from the coupling of two distinct spin-density waves and to be only partly related to the Dzialoshinskii-Moriya interactions. Applying a magnetic field along the two-fold monoclinic axis of CuCl2 yields a decoupling of the spin-density waves modifying the symmetry of the phase and the spin-spiral orientation. The remarkable periodic dependences of the magnetic susceptibility and polarization, on rotating the field in the monoclinic plane, are described theoretically.

  17. Volatile element chemistry in the solar nebula - Na, K, F, Cl, Br, and P

    NASA Technical Reports Server (NTRS)

    Fegley, B., Jr.; Lewis, J. S.

    1980-01-01

    The results of the most extensive set to date of thermodynamic calculations on the equilibrium chemistry of several hundred compounds of the elements Na, K, F, Cl, Br, and P in a solar composition system are reported. Two extreme models of accretion are investigated. In one extreme complete chemical equilibrium between condensates and gases is maintained because the time scale for accretion is long compared to the time scale for cooling or dissipation of the nebula. Condensates formed in this homogeneous accretion model include several phases such as whitlockite, alkali feldspars, and apatite minerals which are found in chondrites. In the other extreme complete isolation of newly formed condensates from prior condensates and gases occurs due to a time scale for accretion that is short relative to the time required for nebular cooling or dissipation. The condensates produced in this heterogeneous accretion model include alkali sulfides, ammonium halides, and ammonium phosphates. None of these phases are found in chondrites. Available observations of the Na, K, F, Cl, Br, and P elemental abundances in the terrestrial planets are found to be compatible with the predictions of the homogeneous accretion model.

  18. AgClBr photonic crystal fibers for the middle infrared

    NASA Astrophysics Data System (ADS)

    Rave, Eran; Ephrat, Pinhas; Katzir, Abraham

    2004-07-01

    Photonic crystal fibers (PCFs) are normally holey fibers, made of silica glass, which is opaque in the mid- and far-infrared spectral range 3-20 μm. We have fabricated novel PCFs by multiple extrusions of silver halide (AgClxBr1-x) crystalline materials, which are highly transparent in this spectral range. These PCFs are composed of two solid materials: the core consists of pure AgBr (n=2.16), and the cladding includes small diameter fiberoptic elements, made of AgCl (n=1.98). These AgCl fiberoptic elements are arranged in two concentric hexagonal rings around the core. This structure gives rise to a cladding region of lower refractive index, thus ensuring total internal reflection. Flexible PCFs of outer diameter 1mm and length of about 1m were fabricated, and their optical properties were measured. Measurements of numerical aperture, laser power transmission and evanescent wave spectroscopy indicated that the PCFs behave like a core-clad structure. There was a good agreement between the results and those obtained by theoretical simulations. Silver halide PCFs would be extremely useful for IR laser power transmission, for IR radiometery and for IR spectroscopy.

  19. Electronic structures and geometries of the XF{sub 3} (X = Cl, Br, I, At) fluorides

    SciTech Connect

    Sergentu, Dumitru-Claudiu; Amaouch, Mohamed; Pilmé, Julien; Galland, Nicolas; Maurice, Rémi

    2015-09-21

    The potential energy surfaces of the group 17 XF{sub 3} (X = Cl, Br, I, At) fluorides have been investigated for the first time with multiconfigurational wave function theory approaches. In agreement with experiment, bent T-shaped C{sub 2v} structures are computed for ClF{sub 3}, BrF{sub 3}, and IF{sub 3}, while we predict that an average D{sub 3h} structure would be experimentally observed for AtF{sub 3}. Electron correlation and scalar relativistic effects strongly reduce the energy difference between the D{sub 3h} geometry and the C{sub 2v} one, along the XF{sub 3} series, and in the X = At case, spin-orbit coupling also slightly reduces this energy difference. AtF{sub 3} is a borderline system where the D{sub 3h} structure becomes a minimum, i.e., the pseudo-Jahn-Teller effect is inhibited since electron correlation and scalar-relativistic effects create small energy barriers leading to the global C{sub 2v} minima, although both types of effects interfere.

  20. High temperature crystal structures and superionic properties of SrCl{sub 2}, SrBr{sub 2}, BaCl{sub 2} and BaBr{sub 2}

    SciTech Connect

    Hull, Stephen; Norberg, Stefan T.; Ahmed, Istaq; Eriksson, Sten G.; Mohn, Chris E.

    2011-11-15

    The structural properties of the binary alkaline-earth halides SrCl{sub 2}, SrBr{sub 2}, BaCl{sub 2} and BaBr{sub 2} have been investigated from ambient temperature up to close to their melting points, using the neutron powder diffraction technique. Fluorite-structured SrCl{sub 2} undergoes a gradual transition to a superionic phase at 900-1100 K, characterised by an increasing concentration of anion Frenkel defects. At a temperature of 920(3) K, the tetragonal phase of SrBr{sub 2} undergoes a first-order transition to a cubic fluorite phase. This high temperature phase shows the presence of extensive disorder within the anion sublattice, which differs from that found in superionic SrCl{sub 2}. BaCl{sub 2} and BaBr{sub 2} both adopt the cotunnite crystal structure under ambient conditions. BaCl{sub 2} undergoes a first-order structural transition at 917(5) K to a disordered fluorite-structured phase. The relationship between the (disordered) crystal structures and the ionic conductivity behaviour is discussed and the influence of the size of the mobile anion on the superionic behaviour is explored. - Graphical abstract: Anomalous behaviour of the lattice expansion of SrCl{sub 2} at temperatures of {approx}1000 K is associated with the gradual transition to a superionic phase, whilst SrBr{sub 2} undergoes a first-order structural transition ({beta}{yields}{alpha}) to a fluorite-structured superionic phase at 920(3) K. Highlights: > Anomalous behaviour of the lattice expansion of SrCl{sub 2} occurs at temperatures {approx}1000 K. > Crystal structure of {beta}-SrBr{sub 2} is described in detail. > On heating, SrBr{sub 2} and BaCl{sub 2} transform to a fluorite-structured superionic phase. > Temperature dependence of the BaCl{sub 2} and BaBr{sub 2} structures is presented. > Nature of the superionic phases within the alkaline-earth halides is discussed.

  1. Lead-Free MA2CuCl(x)Br(4-x) Hybrid Perovskites.

    PubMed

    Cortecchia, Daniele; Dewi, Herlina Arianita; Yin, Jun; Bruno, Annalisa; Chen, Shi; Baikie, Tom; Boix, Pablo P; Grätzel, Michael; Mhaisalkar, Subodh; Soci, Cesare; Mathews, Nripan

    2016-02-01

    Despite their extremely good performance in solar cells with efficiencies approaching 20% and the emerging application for light-emitting devices, organic-inorganic lead halide perovskites suffer from high content of toxic, polluting, and bioaccumulative Pb, which may eventually hamper their commercialization. Here, we present the synthesis of two-dimensional (2D) Cu-based hybrid perovskites and study their optoelectronic properties to investigate their potential application in solar cells and light-emitting devices, providing a new environmental-friendly alternative to Pb. The series (CH3NH3)2CuCl(x)Br(4-x) was studied in detail, with the role of Cl found to be essential for stabilization. By exploiting the additional Cu d-d transitions and appropriately tuning the Br/Cl ratio, which affects ligand-to-metal charge transfer transitions, the optical absorption in this series of compounds can be extended to the near-infrared for optimal spectral overlap with the solar irradiance. In situ formation of Cu(+) ions was found to be responsible for the green photoluminescence of this material set. Processing conditions for integrating Cu-based perovskites into photovoltaic device architectures, as well as the factors currently limiting photovoltaic performance, are discussed: among them, we identified the combination of low absorption coefficient and heavy mass of the holes as main limitations for the solar cell efficiency. To the best of our knowledge, this is the first demonstration of the potential of 2D copper perovskite as light harvesters and lays the foundation for further development of perovskite based on transition metals as alternative lead-free materials. Appropriate molecular design will be necessary to improve the material's properties and solar cell performance filling the gap with the state-of-the-art Pb-based perovskite devices.

  2. Three-coordinate [Cu(II)X(3)](-) (X=Cl, Br), trapped in a molecular crystal.

    PubMed

    Hasselgren, Catrin; Jagner, Susan; Dance, Ian

    2002-03-15

    Mixtures of [Ph(3)PNPPh(3)](+)Cl(-) with CuBr(2) (or CuBr(2)+CuCl(2)) in ethanol/dichloromethane yield crystals containing three-coordinate copper(II) with mixed chloride and bromide ligands, namely [Ph(3)PNPPh(3)](+)[CuCl(0.9)Br(2.1)](-) (1) and [Ph(3)PNPPh(3)](+)[CuCl(2.4)Br(0.6)](-) (2). The trigonal-planar coordination of copper(II) is angularly distorted but unambiguous, as there is no other halide ligand within 6.7 A of the copper atom. Density functional theory (DFT) calculations on planar [CuClBr(2)](-) show that the energy surface for angle bending is very soft. Crystallisation in the presence of CH(3)CN yields [Ph(3)PNPPh(3)](+)[CuCl(0.7)Br(2.3)(NCCH(3))](-) (3), in which there is additional secondary coordination by NCCH(3) (Cu-N 2.44 A). DFT calculations of the potential energy surface for this secondary coordination show that it is remarkably flat (<3 kcal mol(-1) for a variation of Cu-N by 0.8 A). The crystal packing in 1, 2 and 3, which involves multiple phenyl embraces between [Ph(3)PNPPh(3)](+) ions and numerous C-H...Cl and C-H...Br motifs, is associated with intermolecular energies that are larger than the variations in intramolecular energies. For reference, the crystal structures of [Ph(3)PNPPh(3)(+)](2)[Cu(2)Cl(6)](2-) (4) and [Ph(3)PNPPh(3)(+)](2)[Cu(2)Br(6)](2-) (5) are described. We conclude 1) that three-coordinate copper(II) with monatomic halide ligands, although uncommon, can be regarded as normal, 2) that steric control by ligands is not necessary to enforce three-coordination, 3) that a hydrophobic aryl environment stabilises [Cu(Cl/Br)(3)](-), and 4) that the energy change in the transition from three- to four-coordinate copper(II) is very small (ca 5 kcal mol(-1)).

  3. Direct conversion of methane to higher hydrocarbons using AlBr3-HBr superacid catalyst.

    PubMed

    Vasireddy, Sivakumar; Ganguly, Sreemoyee; Sauer, Joe; Cook, Wyndham; Spivey, James J

    2011-01-14

    The direct gas phase catalytic oligomerization of methane at temperatures ≤673 K has been demonstrated using AlBr(3)-HBr superacid. The reaction produces C(2)+ hydrocarbons and hydrogen in a single step at 1 atm in a continuous flow reactor at a nominal residence time of 60 s. The essentially complete conversion of methane appears to be due to protolytic activation of methane in the presence of H(+)AlBr(4)(-).

  4. Speciation in the AlCl3/SO2Cl2 catholyte system.

    SciTech Connect

    Boyle, Timothy J.; Ingersoll, David T.; Tallant, David Robert; Andrews, Nicholas L.; Rodriguez, Mark Andrew; Alam, Todd Michael

    2005-02-01

    The fundamental chemical behavior of the AlCl{sub 3}/SO{sub 2}Cl{sub 2} catholyte system was investigated using {sup 27}Al NMR spectroscopy, Raman spectroscopy, and single-crystal X-ray diffraction. Three major Al-containing species were found to be present in this catholyte system, where the ratio of each was dependent upon aging time, concentration, and/or storage temperature. The first species was identified as [Cl{sub 2}Al({mu}-Cl)]{sub 2} in equilibrium with AlCl{sub 3}. The second species results from the decomposition of SO{sub 2}Cl{sub 2} which forms Cl{sub 2}(g) and SO{sub 2}(g). The SO{sub 2}(g) is readily consumed in the presence of AlCl{sub 3} to form the crystallographically characterized species [Cl{sub 2}Al({mu}-O{sub 2}SCl)]{sub 2} (1). For 1, each Al is tetrahedrally (T{sub d}) bound by two terminal Cl and two {mu}-O ligands whereas, the S is three-coordinated by two {mu}-O ligands and one terminal Cl. The third molecular species also has T{sub d}-coordinated Al metal centers but with increased oxygen coordination. Over time it was noted that a precipitate formed from the catholyte solutions. Raman spectroscopic studies show that this gel or precipitate has a component that was consistent with thionyl chloride. We have proposed a polymerization scheme that accounts for the precipitate formation. Further NMR studies indicate that the precipitate is in equilibrium with the solution.

  5. Nqrs Data for C10H12Br5Cl2InN2O [C10H10Br5Cl2InN2·H2O] (Subst. No. 1254)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C10H12Br5Cl2InN2O [C10H10Br5Cl2InN2·H2O] (Subst. No. 1254)

  6. LiCl Dehumidifier LiBr absorption chiller hybrid air conditioning system with energy recovery

    DOEpatents

    Ko, Suk M.

    1980-01-01

    This invention relates to a hybrid air conditioning system that combines a solar powered LiCl dehumidifier with a LiBr absorption chiller. The desiccant dehumidifier removes the latent load by absorbing moisture from the air, and the sensible load is removed by the absorption chiller. The desiccant dehumidifier is coupled to a regenerator and the desiccant in the regenerator is heated by solar heated hot water to drive the moisture therefrom before being fed back to the dehumidifier. The heat of vaporization expended in the desiccant regenerator is recovered and used to partially preheat the driving fluid of the absorption chiller, thus substantially improving the overall COP of the hybrid system.

  7. Ordered bundles of infrared-transmitting AgClBr fibers: optical characterization of individual fibers.

    PubMed

    Rave, E; Nagli, L; Katzir, A

    2000-09-01

    Silver halide (AgCl(x) Br(1-x)) crystals were extruded to form polycrystalline fibers that are highly transparent in the spectral range 3-30 mum. Ordered bundles consisting of as many as 9000 fibers were fabricated by multiple extrusion steps. The transmission loss of an individual fiber in the 100-fiber bundles was 0.12 dB/cm, and the cross talk between neighboring fibers in the 900-fiber bundles was 25%. Thermal images of bodies at room temperature have been transmitted through the bundles. Such ordered bundles provide a solution for the problem of thermal imaging in regions where there is no line of sight between a thermal camera and a warm object.

  8. Phase Transitions in CsSnCl3 and CsPbBr3 An NMR and NQR Study

    NASA Astrophysics Data System (ADS)

    Sharma, Surendra; Weiden, Norbert; Weiss, Alarich

    1991-04-01

    The phase transitions in CsSnCl3 and CsPbBr3 have been studied by X-ray powder diffraction, by 81Br-NQR and by 'H-, 119Sn-, and 113Cs-NMR. At room temperature in air CsSnCl3 forms a hydrate which can be dehydrated to the monoclinic phase II of CsSnCl3. The high temperature phase I has the Perovskite structure, as the X-ray and NMR experiments show. The three phases of CsPbBr3, known from literature, have been corroborated. The results are discussed in the framework of the group ABX3, A = alkalimetal ion, B = IV main group ion, and X = Halogen ion

  9. Solid-state 207Pb NMR studies of mixed lead halides, PbFX (X=Cl, Br, or I).

    PubMed

    Glatfelter, Alicia; Dybowski, Cecil; Kragten, David D; Bai, Shi; Perry, Dale L; Lockard, Jenny

    2007-04-01

    Solid-state 207Pb NMR studies have been conducted on mixed lead(II) halides of the type PbFX, where X=Cl, Br, or I. NMR data for the mixed halides are compared to the solid-state NMR data for the divalent, binary lead halides, PbX2 (X=F, Cl, Br, I). The NMR data are evaluated in the context of the structures of the compounds and the effects of the mixed halides on the electronic structure of the divalent lead. Data sets for the mixed halides are discussed and compared to those for the regular lead(II) halides.

  10. Airborne Instruments for the In Situ Detection of ClONO2, NO2, ClO, and BrO in the Stratosphere

    NASA Technical Reports Server (NTRS)

    Anderson, James G.

    1999-01-01

    The objective of the research was the development of a new small, lightweight instrument for the detection of ClONO2, NO2, ClO, and BrO, carried aboard a robotic aircraft, specifically the NASA ER-2. The schematic of the instrument is shown. Some of the observations which this instrument is designed to make are discussed. The observations of the instrument during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission are also reviewed.

  11. Blue-emitting Eu2+-activated LaOX (X = Cl, Br, and I) materials: crystal field effect.

    PubMed

    Kim, Donghyeon; Park, Sangha; Kim, Sungyun; Kang, Seong-Gu; Park, Jung-Chul

    2014-11-17

    Novel blue-emitting LaOBr:Eu(2+) and LaOI:Eu(2+) phosphors have been successfully synthesized and compared to LaOCl:Eu(2+). The emission spectra of LaOX:Eu(2+) (X = Cl, Br, and I) show that the peak maxima change somewhat to the red-shift region; 425 nm for LaOCl:Eu(2+), 427 nm for LaOBr:Eu(2+), and 431 nm for LaOI:Eu(2+), which is quite opposite to one based on spectrochemical series (I(-) < Br(-) < Cl(-)). From diffuse reflectance spectra, the band gap energies for LaOCl, LaOBr, and LaOI host lattice are estimated as 5.53 eV (44,594 cm(-1)), 5.35 eV (43,142 cm(-1)), and 4.82 eV (38,868 cm(-1)), respectively, using the Kubelka-Munk function. For LaOX host lattices, the band gap energies are gradually decreased going from Cl to I as the order of energy levels of np orbitals is Cl 3p < Br 4p < I 5p. A quantum wave function calculation from crystal field theory (CFT) indicates the same tendency with experimental data in the LaOX:Eu(2+) (X = Cl, Br, and I) phosphor materials. With considerations of the radial wave function shape, crystral structure differences and electronegativities among phosphor materials, the splitting energies of 5d orbitals are calculaed; ΔECl = 14,597 cm(-1), ΔEBr = 14,864 cm(-1), ΔEI = 15,001 cm(-1) for LaOX:Eu(2+) (X = Cl, Br, and I). It is noteworthy that the crystal field strength decreases when the interatomic distance decreases, which is probably dependent on the ionic radius of halide ions in the series of LaOX:Eu(2+) phosphor materials.

  12. AgBr/nanoAlMCM-41 visible light photocatalyst for degradation of methylene blue dye.

    PubMed

    Pourahmad, A; Sohrabnezhad, Sh; Kashefian, E

    2010-12-01

    A novel photocatalytic material was synthesized by dispersion of AgBr in nanoAlMCM-41 material. The AgBr/nanoAlMCM-41 sample shows strong absorption in the visible region because of the plasmon resonance of Ag nanoparticles in AgBr/nanoAlMCM-41. The catalysts were characterized using XRD (X-ray diffraction), UV-visible diffused reflectance spectra (UV-vis DRS) and scanning electron microscopy (SEM). The photocatalytic activity and stability of the synthesized catalysts were evaluated for methylene blue (MB) degradation in aqueous solution in the presence of 200 W tungsten filament Philips lamp. Several parameters were examined, catalyst amount, pH and initial concentration of MB, AgBr loading. The effect of dosage of photocatalyst was studied in the range 0.05-1.00 g/L. It was seen that 0.1 g/L of photocatalyst is an optimum value for the dosage of photocatalyst. The support size was obtained about 9-100 nm. In the same way, the average size of AgBr nanoparticles was about 10nm before visible radiation. After visible radiation the average size of AgBr nanoparticles was about 25 nm.

  13. Using the Cl/Br ratio as a tracer to identify the origin of salinity in aquifers in Spain and Portugal

    NASA Astrophysics Data System (ADS)

    Alcalá, Francisco J.; Custodio, Emilio

    2008-09-01

    SummaryA study on the applicability of the Cl/Br molar ratio for identifying the origin of groundwater salinity is presented according to the experience gained in Spain and Portugal. Cl/Br ratios in atmospheric bulk deposition have helped to distinguish groundwater in which Cl derives only from atmospheric sources, from groundwater in which Cl is contributed by endogenous, lithological or anthropogenic sources. Considering the seawater Cl/Br ratio of 655 ± 4, Cl/Br ratios may be increased up to 1500 in groundwater by the addition of wastewater loaded with NaCl or leaching of solid waste, and decreased to 300 by the use of Br-based pesticides or leaching farm-animal or septic waste. Leaching and dissolution of natural and industrial NaCl, and of gypsum-rich formations containing some NaCl may yield Cl/Br ratios between one thousand and several thousand, although leaching of potassium halides near salt mines produces Cl/Br ratios below the seawater ratio. When Cl content in groundwater is not affected by extreme evaporation (up to halite saturation at ˜6.2 mol L -1 of NaCl) and if there are no other Cl sources, recharge by rainfall can be estimated by relating Cl in atmospheric bulk deposition to derived groundwater. The Cl/Br ratio appears to be a good tracer for discriminating non-atmospheric Cl contributions to groundwater, provided chemical analyses are accurate, since its variability is not wide. Data have been collected from different areas of Spain and Portugal and are explained and illustrated by two cases described in detail, the Doñana aquifer in southwest Spain and the Canary Islands, both showing the mixing paths.

  14. The reduction of chlorine on carbon in AlCl3-KCl-NaCl melts

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.

    1971-01-01

    Using a rotating vitreous carbon disk electrode, the kinetic parameters for chlorine reduction in an AlCl3-KCl-NaCl (57.5-12.5-30 mol percent) melt were determined. It was found that the reduction of chlorine occurs according to two paths, with the first step probably being rate-determining.

  15. Chemical Properties of Electronically Excited Halogen Atoms X(2P1/2) (X=F,Cl,Br,I)

    NASA Astrophysics Data System (ADS)

    Chichinin, A. I.

    2006-06-01

    The experimental data on elementary processes (collisional deactivation, chemical reactions, photodissociation) involving spin-orbitally excited X(2P1/2) atoms (X=F,Cl,Br,I) published up to the middle of 2005 are summarized in the present compilation. Critical evaluation of the data and limited comparison to theoretical calculations are also presented.

  16. Estimation of S, F, Br, Cl, and P Fluxes at Mid Ocean Ridges

    NASA Astrophysics Data System (ADS)

    Kagoshima, T.; Sano, Y.; Takahata, N.; Jung, J.; Amakawa, H.; Kumagai, H.

    2011-12-01

    It is known that superficial volatile elements have been accumulated by degassing from the solid Earth. Studies that use noble gases as tracers have been conducted to investigate the degassing history of the Earth, which suggests that the significant degassing occurred in the early Earth. C and N fluxes were well documented in literatures. In order to estimate the other fluxes of volatile elements from mantle, we measured S, F, Br, Cl, and P concentrations trapped in vesicles in mid-ocean ridge basalts (MORBs) and back-arc basin basalts (BABBs). Highly reactive elements such as sulfur and fluorine in the sample were extracted into the alkali solution at the crushing: crush leaching. We selected fresh glassy aliquots from MORBs and BABBs and put them in a crusher with an iron ball and 1-2 cm^{3} of 4M aqueous sodium hydroxide. Then, we crushed the samples with the solution kept frozen at the liquid nitrogen temperature to avoid the adhesion of the solution to the inside of the crusher. After crushing, we froze the solution again, and introduced volatiles in the gas phase into the purification vacuum line. At first, we removed volatile elements except He and Ne by a U-tube and activated charcoals at the temperature of liquid nitrogen and hot Ti-getters. We measured ^{4}He/^{20}Ne ratio of the gas by a quadrupole mass spectrometer and removed Ne by a cryogenic charcoal trap at 40K. Then, the He fraction was introduced into VG5400 mass spectrometer and the ^{3}He/^{4}He ratio was measured. Immediately after the sample analysis, we measured HESJ (He standard of Japan; 20.4 R_{A}) for calibration. For sulfur measurement, 1-2 cm^{3} of 30% hydrogen peroxide were added into the filtered sodium hydroxide solutions. Thus all sulfur compounds were quantified as sulfate ions and F, Br, Cl, and P were measured by ion chromatography (Dionex-320). We collected fine powders of basalt glass by filtering through a stainless steel sieve and measured their weight to estimate the

  17. Computational study on thermochemical properties for perhalogenated methanols (CX3OH) (X = F, Cl, Br).

    PubMed

    Alrawashdeh, Ahmad I; Poirier, Raymond A

    2015-04-16

    The perhalogenated methanols (CX3OH; X = F, Cl, and Br) are found in the atmosphere as products of the degradation of halocarbons. The thermochemical properties for these molecules have been calculated at the HF, MP2, and B3LYP levels of theories in conjunction with six different basis sets as well as at G3MP2 and CBS-QB3. Calculated properties include the gas-phase enthalpies of formation (ΔfH(0)), gas-phase acidities (ΔacidG(0)), gas-phase proton affinity, and bond dissociation energies of the C-O and O-H bonds of CX3OH. Excellent agreement is found between the results obtained using G3MP2 and CBS-QB3 methods and the available experimental data. The results obtained using MP2 are more consistent with the experimental, G3MP2, and CBS-QB3 values than those computed at B3LYP. In general, the 6-311+G(d,p) basis set when combined with the HF or MP2 level of theory produced better results than other basis sets considered in this study.

  18. Compression icing of room-temperature NaX solutions (X = F, Cl, Br, I).

    PubMed

    Zeng, Qingxin; Yan, Tingting; Wang, Kai; Gong, Yinyan; Zhou, Yong; Huang, Yongli; Sun, Chang Q; Zou, Bo

    2016-05-18

    In situ Raman spectroscopy revealed that transiting H2O/NaX (∼64) solutions into an ice VI phase and then into an ice VII phase at a temperature of 298 K requires excessive pressures with respect to pure water. The increase of the critical pressures varies with the solute type in the Hofmeister series order: X = I > Br > Cl > F ∼ 0. The results suggest that the solute hydration creates electric fields that lengthen and soften the O:H nonbond and meanwhile shorten and stiffen the H-O bond through O-O Coulomb repulsion. Compression, however, does the opposite to solute electrification upon the O:H-O bond relaxation. Therefore, compression of the aqueous solutions recovers the electrification-deformed O:H-O bond first and then proceeds to the phase transitions, which requires excessive energy for the same sequence of phase transitions. Ice exclusion of solute disperses the frequencies of characteristic phonons and the critical pressures with unlikely new bond formation.

  19. Simulation of the resonance Raman spectra for 5-halogenated (F, Cl, and Br) uracils.

    PubMed

    Sun, Shuai; Brown, Alex

    2015-04-30

    The resonance Raman spectra of the 5-halogenated (F, Cl, and Br) uracils are simulated via the Herzberg-Teller (HT) short-time dynamics formalism. The gradient of the S1 excited state is computed at the CAMB3LYP/aug-cc-pVTZ level of theory in the conductor-like polarizable continuum model for water (C-PCM, H2O), based on the equilibrium geometry determined using PBE0/aug-cc-pVTZ in H2O (C-PCM). The simulated resonance Raman spectra show good agreement with the experimental spectra in terms of both peak positions and intensities. The differences between the resonance Raman spectra of the three 5-halogenated uracils, caused by the effect of halogen substitution, are examined in terms of ground-state normal-mode eigenvectors and excited-state Cartesian gradients, according to the HT formalism. The differences in the normal-mode eigenvectors and excited-state Cartesian gradients between 5-fluorouracil and 5-chlorouracil are used to interpret the dissimilarity between their resonance Raman spectra. Meanwhile, the similarity between the spectra of 5-chlorouracil and 5-bromouracil is explained by the correspondence between their normal modes and excited-state gradients.

  20. On the spectroscopic and thermochemical properties of ClO, BrO, IO, and their anions.

    PubMed

    Peterson, Kirk A; Shepler, Benjamin C; Figgen, Detlev; Stoll, Hermann

    2006-12-28

    A coupled cluster composite approach has been used to accurately determine the spectroscopic constants, bond dissociation energies, and heats of formation for the X1(2)II(3/2) states of the halogen oxides ClO, BrO, and IO, as well as their negative ions ClO-, BrO-, and IO-. After determining the frozen core, complete basis set (CBS) limit CCSD(T) values, corrections were added for core-valence correlation, relativistic effects (scalar and spin-orbit), the pseudopotential approximation (BrO and IO), iterative connected triple excitations (CCSDT), and iterative quadruples (CCSDTQ). The final ab initio equilibrium bond lengths and harmonic frequencies for ClO and BrO differ from their accurate experimental values by an average of just 0.0005 A and 0.8 cm-1, respectively. The bond length of IO is overestimated by 0.0047 A, presumably due to an underestimation of molecular spin-orbit coupling effects. Spectroscopic constants for the spin-orbit excited X2(2)III(1/2) states are also reported for each species. The predicted bond lengths and harmonic frequencies for the closed-shell anions are expected to be accurate to within about 0.001 A and 2 cm-1, respectively. The dissociation energies of the radicals have been determined by both direct calculation and through use of negative ion thermochemical cycles, which made use of a small amount of accurate experimental data. The resulting values of D0, 63.5, 55.8, and 54.2 kcal/mol for ClO, BrO, and IO, respectively, are the most accurate ab initio values to date, and those for ClO and BrO differ from their experimental values by just 0.1 kcal/mol. These dissociation energies lead to heats of formation, DeltaH(f) (298 K), of 24.2 +/- 0.3, 29.6 +/- 0.4, and 29.9 +/- 0.6 kcal/mol for ClO, BrO, and IO, respectively. Also, the final calculated electron affinities are all within 0.2 kcal/mol of their experimental values. Improved pseudopotential parameters for the iodine atom are also reported, together with revised correlation

  1. Halogen (F, Cl, Br, I) behaviour in subducting slabs: A study of lawsonite blueschists in western Turkey

    NASA Astrophysics Data System (ADS)

    Pagé, Lilianne; Hattori, Keiko; de Hoog, Jan C. M.; Okay, Aral I.

    2016-05-01

    We examined the F, Cl, Br and I abundance of minimally retrogressed lawsonite blueschists from the Tavsanli Zone in northwest Turkey to evaluate the behaviour of halogens in subduction zones, and to determine the role coexisting high pressure minerals may play in transporting the halogens to the Earth's mantle. The blueschists contain sodic amphibole and lawsonite, with variable amounts of phengite and chlorite, and minor apatite. A positive correlation between Cl, Br and I contents in bulk rocks suggests their overall coherent behaviour in subduction zones, although high ratios of I/Cl and Br/Cl compared to altered oceanic crust indicate that Cl is preferentially lost relative to Br and I before or during blueschist metamorphism. Iodine and F are enriched relative to altered oceanic crust, suggesting incorporation from marine sediments. In situ analyses of minerals in thin sections reveal F preferentially concentrates in apatite (avg. 3.13 wt%), over phengite (482 ppm), lawsonite (avg. 413 ppm) and Na-amphibole (257 ppm). Chlorine also preferentially resides in apatite (138 ppm), followed by equal partitioning between phengite (59 ppm) and Na-amphibole (56 ppm), and lower concentrations in lawsonite (27 ppm). Upon apatite decomposition at a depth of ∼200 km, F may redistribute into lawsonite and phengite in slabs, whilst Cl is likely expelled to the overlying mantle wedge. Given the stability of lawsonite and phengite to a depth of 280-300 km in cold subduction zones, they may transport F beyond subarc depths, contributing to the high F in magmas derived from the deep mantle.

  2. Growth of PbX2 and CsPbX3 (X = Cl, Br) mesoscopic phases in alkali halide host lattices

    NASA Astrophysics Data System (ADS)

    Polak, K.; Nitsch, K.; Nikl, M.

    Formation of PbCl2 and CsPbBr3 microphases in NaCl and CsBr respectively is studied using mainly an absorption spectroscopy. The absorption of NaCl: Pb crystal was investigated as a function of annealing temperature and duration of thermal treatment. Changes in the position and shape of the exciton band were studied in CsBr: Pb absorption spectrum. The results showed that the shape of CsPbBr3 microcrystals is far from a spherical one. The microcrystals probably grow as highly elongated discs.

  3. Observation of parity nonconservation in the integrated. gamma. spectrum from (n,. gamma. ) reactions in Cl, Br, Cd, Sn, and La nuclei

    SciTech Connect

    Vesna, V.A.; Kolomenskii, E.A.; Lobashev, V.M.; Nazarenko, V.A.; Pirozhkov, A.N.; Smotritskii, L.M.; Sobolev, Y.V.; Titov, N.A.

    1982-09-05

    A P-odd asymmetry has been observed in the emission of ..gamma.. rays upon the capture of polarized thermal neutrons by Cl, Br, and La nuclei. A circular polarization of the ..gamma.. rays has been observed during the capture of unpolarized neutrons by Cl, Br, Sn, and La nuclei.

  4. [(Ph)3PBr][Br7], [(Bz)(Ph)3P]2[Br8], [(n-Bu)3MeN]2[Br20], [C4MPyr]2[Br20], and [(Ph)3PCl]2[Cl2I14]: extending the horizon of polyhalides via synthesis in ionic liquids.

    PubMed

    Wolff, Michael; Okrut, Alexander; Feldmann, Claus

    2011-11-21

    The five polyhalides [(Ph)(3)PBr][Br(7)], [(Bz)(Ph)(3)P](2)[Br(8)], [(n-Bu)(3)MeN](2)[Br(20)], [C(4)MPyr](2)[Br(20)] ([C(4)MPyr] = N-butyl-N-methylpyrrolidinium), and [(Ph)(3)PCl](2)[Cl(2)I(14)] were prepared by the reaction of dibromine and iodine monochloride in ionic liquids. The compounds [(Ph)(3)PBr][Br(7)] and [(Bz)(Ph)(3)P](2)[Br(8)] contain discrete pyramidal [Br(7)](-) and Z-shaped [Br(8)](2-) polybromide anions. [(n-Bu)(3)MeN](2)[Br(20)] and [C(4)MPyr](2)[Br(20)] exhibit new infinite two- and three-dimensional polybromide networks and contain the highest percentage of dibromine ever observed in a compound. [(Ph)(3)PCl](2)[Cl(2)I(14)] also consists of a three-dimensional network and is the first example of an infinite polyiodine chloride. All compounds were obtained from ionic liquids as the solvent that, on the one hand, guarantees for a high stability against strongly oxidizing Br(2) and ICl and that, on the other hand, reduces the high volatility of the molecular halogens.

  5. Syntheses and structure of hydrothermally prepared CsNiX{sub 3} (X=Cl, Br, I)

    SciTech Connect

    Raw, Adam D.; Ibers, James A.; Poeppelmeier, Kenneth R.

    2012-08-15

    During reinvestigation of the hydrothermal synthesis reported earlier of the compound cesium nickel phosphide, 'CsNiP', we arrived at a new route to the synthesis of the cesium nickel halide compounds CsNiX{sub 3} (X=Cl, Br, I). The method has also been shown to extend to cobalt and iron compounds. Single crystals of these compounds were synthesized in phosphoric acid in sealed autoclaves. Their structures were determined by single-crystal X-ray diffraction methods. The compounds crystallize in the hexagonal space group P6{sub 3}/mmc in the BaNiO{sub 3} structure type. The synthetic method and the resultant crystallographic details for CsNiCl{sub 3} are essentially identical with those reported earlier for the synthesis and structure of 'CsNiP'. - Graphical abstract: The CsNiX{sub 3} (X=Cl, Br, I) structure. Cesium is blue, nickel is in dark green polyhedra, halide is brown. Highlights: Black-Right-Pointing-Pointer A hydrothermal approach to single crystal growth of cesium transition-metal halides. Black-Right-Pointing-Pointer Reexamination of 'CsNiP' to determine its composition as CsNiCl{sub 3}. Black-Right-Pointing-Pointer X-ray single-crystal structures of CsNiBr{sub 3} and CsNiI{sub 3}.

  6. On the structural parameters and vibrational spectra of some XNCS and XSCN (X=H, F, Cl, Br) molecules

    NASA Astrophysics Data System (ADS)

    Durig, James R.; Zheng, Chao; Deeb, Hamoudeh

    2006-02-01

    Ab initio calculations with full electron correlation by the perturbation method to second order and hybrid density functional theory calculations by the B3LYP method utilizing the 6-31G(d), 6-311+G(d,p), and 6-311+G(2d,2p) basis sets have been carried out for the XNCS and XSCN (X=H, F, Cl, Br) molecules. From these calculations, force constants, vibrational frequencies, infrared intensities, Raman activities, depolarization ratios, and structural parameters have been determined and compared to the experimental quantities when available. By combining previously reported rotational constants for HNCS, ClSCN and BrSCN with the ab initio MP2/6-311+G(d,p) predicted parameters, adjusted r0 parameters have been obtained. The structural parameters for isothiocyanic acid are: r(H-N)=0.996(5) Å; r(N dbnd6 C)=1.208(3) Å; r(C=S)=1.568(3) Å; ∠HNC=132.0(5)°; ∠NCS=172.9(5)°. These reported angles have much lower uncertainties than those previously reported from the microwave data alone. The ab initio predicted barrier to molecular linearity of HNCS is 917±44 cm -1 which is in excellent agreement with the experimental value of 900±200 cm -1. The r0 parameters for ClSCN are: r(Cl-S)=2.023(5); r(S-C)=1.694(3); r(C tbnd6 N)=1.156(3) Å; ∠ClSC=99.6(5) and ∠SCN=174.4(5)° and for BrSCN are: r(Br-S)=2.197(5); r(S-C)=1.681(3); r(C tbnd6 N)=1.158(3) Å; ∠BrSC=99.5(5) and ∠SCN=174.7(5)°. Structural parameters are also estimated for HSCN and FSCN. The predicted frequencies for the fundamentals of HNCS and DNCS compare favorably to the experimental values but several of their predicted intensities differ significantly from the observed spectra. The frequencies for the reported bending modes of ClSCN and BrSCN do not agree with the predicted values and further experimental studies are needed for providing confident assignments for these fundamentals.

  7. Na-Cl-Br systematics of fluid inclusions from Mississippi Valley-type deposits, Appalachian Basin: Constraints on solute origin and migration paths

    SciTech Connect

    Kesler, S.E.; Martini, A.M.; Appold, M.S.; Walter, L.M.; Huston, T.J.; Furman, F.C.

    1996-01-01

    This study evaluated Na-Cl-Br systematics of fluid inclusion-hosted brines in Mississippi Valley-type (MVT) deposits from the Appalachian Basin. Unlike other geochemical tracers such as lead and strontium isotopes which constrain metal sources, Na-Cl-Br systematics identify sources of brine salinity. Saline formation waters can vary systematically within and between basins with regard to their Na-Cl-Br compositions depending on the importance of halite dissolution relative to retention of subaerially evaporated seawater for the halogen budget. Oil field brine compositions from the Illinois and Appalachian basins are quite distinct in their Na-Cl-Br systematics. Compositions of saline fluid inclusions in MVT deposits generally are consistent with these regional differences. These results shed new light on the extent of regional flow systems and on the geochemical evolution of saline fluids responsible for mineralization. Nearly all fluid inclusions analyzed from the Appalachian MVT deposits have Na/Br and Cl/Br ratios less than modern seawater, consistent with ratios observed in marine brines involved in halite precipitation. The Na-Cl-Br systematics of the brines responsible for Appalachian MVT deposits may be inherited from original marine brines refluxed into the porous carbonate shelf sediments that host these deposits. The Cl/Br and Na/Br ratios of most fluid inclusion-hosted brines from Appalachian MVT sphalerites and fluorites fall into two compositional groups, one from the Lower Cambrian paleoaquifer and another from the Lower Ordovician paleoaquifer. Leachates from most MVT barite deposits form a third compositional group having lower Na/Br and Cl/Br ratios than the other two. Appalachian MVT leachate compositions differ significantly from those in MVT deposits in the Cincinnati arch-midcontinent region suggesting that these two MVT provinces formed from brines of different origin or flow path. 59 refs., 8 figs., 2 tabs.

  8. Hydration of the calcium(II) ion in an aqueous solution of common anions (ClO4-, Cl-, Br-, and NO3-).

    PubMed

    Rudolph, Wolfram W; Irmer, Gert

    2013-03-21

    Raman spectra of aqueous calcium salt solutions, Ca(ClO(4))(2), CaCl(2), CaBr(2), and Ca(NO(3))(2), were measured from the concentrated solution stage to more dilute solutions (6.08-0.1 mol L(-1)) at 23 °C in water and heavy water down to 40 cm(-1). In aqueous Ca(ClO(4))(2) solutions a strongly polarized band at 283 cm(-1) (full width at half height (fwhh) = 68 cm(-1)) was observed. The mode at 283 cm(-1) was assigned to the Ca-O symmetric stretching vibration of the hexa-aqua Ca(2+) ion, [Ca(OH(2))(6)](2+), and the integrated band intensity showed a linear dependency with Ca(ClO(4))(2) concentration. In a Ca(ClO(4))(2) solution of heavy water a similar band was observed at 268 cm(-1) (fwhh = 64 cm(-1)) of the deuterated species, [Ca(OD(2))(6)](2+). In the OH stretching region of water a band of weakly H-bonded O-H oscillators was detected at 3550 cm(-1) due to O-H···ClO(4)(-). In D(2)O solutions a similar band was found at 2590 cm(-1) due to O-D···ClO(4)(-). The band at 283 cm(-1), in addition to the restricted translation mode of water at ~180 cm(-1), was also observed in dilute to moderately concentrated CaCl(2) and CaBr(2) solutions. This fact is strong evidence that neither Cl(-) nor Br(-) penetrate the first hydration sphere of Ca(2+) in solution with mol ratio H(2)O : CaCl(2)/CaBr(2)≥ 18 : 1 and the coordination number is unchanged. Furthermore, the influence of CaCl(2) on the water bands of the librational band region (300-900 cm(-1)), the deformation band of water and the O-H stretching region has been described. In a hydrate melt and very concentrated solutions of CaCl(2) with a mol ratio H(2)O : CaCl(2)≤ 9 : 1, however, contact ion pairs between Ca(2+) and Cl(-) are formed and the 283 cm(-1) band vanishes. Preliminary DFT calculations on the contact ion pair, [Ca(OH(2))(5)Cl](+), confirm its existence in such hydrate melts. In aqueous solutions of Ca(NO(3))(2), NO(3)(-) penetrates the first hydration sphere and spectroscopic evidence of weak

  9. Na/beta-alumina/NaAlCl4, Cl2/C circulating cell

    NASA Astrophysics Data System (ADS)

    Cherng, Jing-Yih; Bennion, Douglas N.

    1987-09-01

    A study was made of a high specific energy battery based on a sodium negative electrode and a chlorine positive electrode with molten AlCl3-NaCl electrolyte and a solid beta alumina separator. The basic performance of a Na beta-alumina NaAlCl4, Cl2/C circulating cell at 200 C was demonstrated. This cell can be started at 150 C. The use of melting sodium chloroaluminate electrolyte overcomes some of the material problems associated with the high working temperatures of present molten salt systems, such as Na/S and LiAl/FeS, and retains the advantages of high energy density and relatively efficient electrode processes. Preliminary investigations were conducted on a sodium-chlorine static cell, material compability, electrode design, wetting, and theoretical calculations to assure a better chance of success before assembling a Na/Cl2 circulating cell. Mathematical models provide a theoretical explanation for the performance of the NaCl2 battery. The results of mathematical models match the experimental results very well. According to the result of the mathematical modeling, an output at 180 mA/sq cm and 3.2 V can be obtained with optimized cell design.

  10. Structure and crystal fields of PrBr3 and PrCl3: A neutron study

    NASA Astrophysics Data System (ADS)

    Schmid, B.; Hälg, B.; Furrer, A.; Urland, W.; Kremer, R.

    1987-04-01

    The crystal structures of PrX3 (X=Br, Cl) and particularly the detailed coordination of the halides X have been studied by neutron diffraction on polycrystalline samples in the temperature range between 4.2 and 293 K. Furthermore, the crystalline electric fields (CEF) in the two compounds have been investigated by inelastic neutron scattering experiments on single-crystal samples. The observed CEF transitions have been identified according to the transition matrix elements and the polarization factor in the neutron cross section, which allowed an unambiguous determination of the four CEF parameters for hexagonal symmetry. The energetic ordering of the CEF levels in PrBr3 and PrCl3 are considerably different which can be understood in terms of the different geometric coordination of the halides determined from the diffraction results.

  11. Bi3+ Luminescence in ABiO2Cl (A = Sr, Ba) and BaBiO2Br

    SciTech Connect

    Porter-Chapman, Yetta D.; Bourret-Courchesne, Edith E.; Derenzo,Stephen E.

    2007-01-18

    Trivalent bismuth luminescence is reported in three Sillenbismuth oxyhalide phases, SrBiO2Cl, BaBiO2Cl, and BaBiO2Br. Thesecompounds exhibit Bi 6s6->6 s2 emission under UV and X-ray radiation.At room temperature, BaBiO2Cl shows the most intense light emission, withspectral and decay properties similar to those found in Bi4Ge3O12 (BGO).At low temperatures, each phase show an increase in the photoluminescenceintensities and a narrowing of the emission peaks. In contrast to thetemperature dependence of BGO, X-ray excited luminescence intensities ofall three phases remain relatively constant throughout the temperaturerange 10 - 295 K. This result indicates that the Sillen phases undergoless thermal quenching than BGO. The low temperature and room temperatureradio-luminescence decay times were determined from pulsed x-raymeasurements. At room temperature, SrBiO2Cl exhibits faster decays thanBGO, while, BaBiO2Cl and BaBiO2Br have decay times similar toBGO.

  12. Guest-tuned spin crossover in flexible supramolecular assemblies templated by a halide (Cl(-), Br(-) or I(-)).

    PubMed

    Darawsheh, M D; Barrios, L A; Roubeau, O; Teat, S J; Aromí, G

    2017-01-03

    Ligand 1,3-bis(3-(pyridin-2-yl)-1H-pyrazol-5-yl)benzene, L, forms mononuclear spin crossover complexes [FeL3](2+) with pendant arms that cause them to dimerize through numerous intermolecular interactions forming supramolecular (X@[FeL3]2)(3+) cations. They have the flexibility to encapsulate Cl(-), Br(-) or I(-), which allow tuning the magnetic properties, in the solid state and in solution.

  13. Response properties of AgCl and AgBr under an external static electric field: A density functional study

    NASA Astrophysics Data System (ADS)

    Praveen, C. S.; Kokalj, A.; Rérat, M.; Valant, M.

    2012-10-01

    Density functional theory has been applied to investigate the effect of electric field on the electronic properties of AgCl and AgBr crystals using a static electric field perturbation. A reduction in the band gap value and widening of the band widths are observed with increase in the macroscopic field value indicating a considerable red shift in the absorption spectrum of AgCl and AgBr in the presence of an external electric field. Further, dielectric properties and lattice vibrations at the gamma point are calculated with three different functionals using the CPKS and the Berry phase approach as implemented in CRYSTAL09 code. Finally, the breakdown strength of AgCl and AgBr crystal is evaluated using Callen's equation. In contrast to the case of alkali halides, it is found that the inclusion of the numerically calculated effective mass ratio into the Callen's equation considerably improves the agreement between the calculated dielectric strength and the available experimental datum.

  14. Photochemistry in a dense manifold of electronic states: Photodissociation of CH{sub 2}ClBr

    SciTech Connect

    Valero, Rosendo; Truhlar, Donald G.

    2012-09-14

    We report electronically nonadiabatic dynamics calculations including spin-orbit coupling for the photodissociation of CH{sub 2}ClBr to yield Cl({sup 2}P{sub 3/2}), Cl({sup 2}P{sub 1/2}), Br({sup 2}P{sub 3/2}), and Br({sup 2}P{sub 1/2}). The potential energy is a 24 Multiplication-Sign 24 matrix (divided up here into four 6 Multiplication-Sign 6 blocks in a first approximation to the problem), in a spin-coupled fully diabatic representation obtained by combining the spin-free fourfold way with single-center spin-orbit coupling constants. The spin-free calculations are carried out by multiconfiguration quasidegenerate perturbation theory, and the fully diabatic potentials including spin-orbit coupling are fit to a matrix reactive force field. The dynamics are carried out by the coherent switches with decay of mixing method in the diabatic representation. The results show qualitative agreement with experiment.

  15. Photochemistry in a dense manifold of electronic states: Photodissociation of CH{sub 2}ClBr

    SciTech Connect

    Valero, Rosendo; Truhlar, Donald G.

    2012-12-14

    We report electronically nonadiabatic dynamics calculations including spin-orbit coupling for the photodissociation of CH{sub 2}ClBr to yield Cl({sup 2}P{sub 3/2}), Cl({sup 2}P{sub 1/2}), Br({sup 2}P{sub 3/2}), and Br({sup 2}P{sub 1/2}). The potential energy is a 24 Multiplication-Sign 24 matrix (divided up here into four 6 Multiplication-Sign 6 blocks in a first approximation to the problem), in a spin-coupled fully diabatic representation obtained by combining the spin-free fourfold way with single-center spin-orbit coupling constants. The spin-free calculations are carried out by multiconfiguration quasidegenerate perturbation theory, and the fully diabatic potentials including spin-orbit coupling are fit to a matrix reactive force field. The dynamics are carried out by the coherent switches with decay of mixing method in the diabatic representation. The results show qualitative agreement with experiment.

  16. Laser microprobe analyses of Cl, Br, I, and K in fluid inclusions: Implications for sources of salinity in some ancient hydrothermal fluids

    USGS Publications Warehouse

    Böhlke, J.K.; Irwin, J.J.

    1992-01-01

    The relative concentrations of Cl, Br, I, and K in fluid inclusions in hydrothermal minerals were measured by laser microprobe noble gas mass spectrometry on irradiated samples containing 10-10 to 10-8 L of fluid. Distinctive halogen signatures indicate contrasting sources of fluid salinity in fluid inclusions from representative "magmatic" (St. Austell), "metamorphic" (Alleghany), and "geothermal" (Creede, Salton Sea) aqueous systems. Br/Cl mol ratios are lowest at Salton Sea (0.27-0.33 ?? 10-3), where high salinities are largely due to halite dissolution; intermediate at St. Austell (0.85 ?? 10-3), possibly representative of magmatic volatiles; and highest (near that of seawater) at Creede (1.5-2.1 ?? 10-3) and Alleghany (1.2-2.4 ?? 10-3), where dissolved halogens probably were leached from volcanic and (or) nonevaporitic sedimentary rocks. I C1 mol ratios are lowest (near that of seawater) at Creede (1-14 ?? 10-6), possibly because organisms scavenged I during low temperature recharge; intermediate at Salton Sea (24-26 ?? 10-6) and St. Austell (81?? 10-6); and highest at Alleghany (320-940 ?? 10-6), probably because the fluids interacted with organic-rich sediments at high temperatures before being trapped. K Cl mol ratios indicate disequilibrium with respect to hypothetical feldspathic alkali-Al-silicate mineral buffers at fluid inclusion trapping temperatures at Creede, and large contributions of (Na, K)-bicarbonate to total fluid ionic strength at Alleghany. Significant variations in Cl/Br/I/K ratios among different fluid inclusion types are correlated with previously documented mineralization stages at Creede, and with the apparent oxidation state of dissolved carbon at Alleghany. The new data indicate that Cl/ Br/I ratios in hydrothermal fluid inclusions vary by several orders of magnitude, as they do in modern surface and ground waters. This study demonstrates that halogen signatures of fluid inclusions determined by microanalysis yield important

  17. Electrodeposition of Al-Ta alloys in NaCl-KCl-AlCl3 molten salt containing TaCl5

    NASA Astrophysics Data System (ADS)

    Sato, Kazuki; Matsushima, Hisayoshi; Ueda, Mikito

    2016-12-01

    To form Al-Ta alloys for high temperature oxidation resistance components, molten salt electrolysis was carried out in an AlCl3-NaCl-KCl melt containing TaCl5 at 423 K. The voltammogram showed two cathodic waves at 0.45 V and 0.7 V vs. Al/Al(III), which may correspond to reduction from Ta(V) to Ta(III) and from Ta(III) to tantalum metal, respectively. Electrodeposits of Al and Ta were obtained in the range from -0.05 to 0.3 V and the highest concentration of Ta in the electrodeposit was 72 at% at 0.3 V. With increasing Ta content in the alloy, the morphology of the electrodeposits became powdery and the particle size smaller.

  18. Flash photolysis of transient radicals. 1. X/sub 2//sup -/ with X = Cl, Br, I, and SCN

    SciTech Connect

    Nagarajan, V.; Fessenden, R.W.

    1985-05-23

    The radicals Cl/sub 2//sup -/, Br/sub 2//sup -/, I/sub 2//sup -/, and (SCN)/sub 2//sup -/ were prepared by photolysis of appropriate chemical systems with one laser and were subsequently photolyzed with a second laser. The first three species were photolyzed at 355 nm, and (SCN)/sub 2//sup -/ was photolyzed at 532 nm, I/sub 2//sup -/ was also photolyzed at 700 nm. In each case, dissociation into the fragments X and X/sup -/ was detected by a bleach in the absorption of X/sub 2//sup -/. In no case was electron photodetachment observed. Observation of the recovery of the original absorption allowed the corresponding rate constant to be measured. In the case of Cl/sub 2//sup -/ the bleach in absorption does not completely recovery and the loss of absorption is dose dependent. Because the presence of acid allows a more complete recovery, it can be concluded that the product Cl atom is photolyzed by a second photon to produce OH and Cl/sup -/. This photoreaction is direct experimental evidence that the absorption band of Cl involves charge transfer from solvent. Detailed analysis of the bleaching and recovery behavior at high Cl/sup -/ concentrations showed no time lag which could be attributed to the /sup 2/P/sub 1/2/ Cl atom, implying a short lifetime for this species. 13 references, 6 figures, 2 tables.

  19. Double-inversion mechanisms of the X⁻ + CH₃Y [X,Y = F, Cl, Br, I] SN2 reactions.

    PubMed

    Szabó, István; Czakó, Gábor

    2015-03-26

    The double-inversion and front-side attack transition states as well as the proton-abstraction channels of the X(-) + CH3Y [X,Y = F, Cl, Br, I] reactions are characterized by the explicitly correlated CCSD(T)-F12b/aug-cc-pVTZ(-PP) level of theory using small-core relativistic effective core potentials and the corresponding aug-cc-pVTZ-PP bases for Br and I. In the X = F case the double-inversion classical(adiabatic) barrier heights are 28.7(25.6), 15.8(13.4), 13.2(11.0), and 8.6(6.6) kcal mol(-1) for Y = F, Cl, Br, and I, respectively, whereas the barrier heights are in the 40-90 kcal mol(-1) range for the other 12 reactions. The abstraction channels are always above the double-inversion saddle points. For X = F, the front-side attack classical(adiabatic) barrier heights, 45.8(44.8), 31.0(30.3), 24.7(24.2), and 19.5(19.3) kcal mol(-1) for Y = F, Cl, Br, and I, respectively, are higher than the corresponding double-inversion ones, whereas for the other systems the front-side attack saddle points are in the 35-70 kcal mol(-1) range. The double-inversion transition states have XH···CH2Y(-) structures with Cs point-group symmetry, and the front-side attack saddle points have either Cs (X = F or X = Y) or C1 symmetry with XCY angles in the 78-88° range. On the basis of the previous reaction dynamics simulations and the minimum energy path computations along the inversion coordinate of selected XH···CH2Y(-) systems, we suggest that the double inversion may be a general mechanism for SN2 reactions.

  20. Modulation of electronic and optical properties in mixed halide perovskites CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x)

    NASA Astrophysics Data System (ADS)

    Zhou, Ziqi; Cui, Yu; Deng, Hui-Xiong; Huang, Le; Wei, Zhongming; Li, Jingbo

    2017-03-01

    The recent discovery of lead halide perovskites with band gaps in the visible presents important potential in the design of high efficient solar cells. CsPbCl3, CsPbBr3 and CsPbI3 are stable compounds within this new family of semiconductors. By performing the first-principles calculation, we explore the structural, electronic and optical properties of CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x) with various compositions of halide atoms. Structural stability is demonstrated with halide atoms distributing randomly at the halide atomic sites. CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x) exhibit the modulation of their band gaps by varying the halide composition. Our results also indicate that CsPbCl3xBr3(1-x) and CsPbBr3xI3(1-x) with different halide compositions are suitable to application to solar cells for the general features are well preserved. Good absorption to lights of different wavelengths has been obtained in these mixed halide perovskites.

  1. Brightly Luminescent and Color-Tunable Formamidinium Lead Halide Perovskite FAPbX3 (X = Cl, Br, I) Colloidal Nanocrystals.

    PubMed

    Levchuk, Ievgen; Osvet, Andres; Tang, Xiaofeng; Brandl, Marco; Perea, José Darío; Hoegl, Florian; Matt, Gebhard J; Hock, Rainer; Batentschuk, Miroslaw; Brabec, Christoph J

    2017-04-11

    In the past few years, hybrid organic-inorganic and all-inorganic metal halide perovskite nanocrystals have become one of the most interesting materials for optoelectronic applications. Here, we report a facile and rapid room temperature synthesis of 15-25 nm formamidinium CH(NH2)2PbX3 (X = Cl, Br, I, or mixed Cl/Br and Br/I) colloidal nanocrystals by ligand-assisted reprecipitation (LARP). The cubic and platelet-like nanocrystals with their emission in the range of 415-740 nm, full width at half-maximum (fwhm) of 20-44 nm, and radiative lifetimes of 5-166 ns enable band gap tuning by halide composition as well as by their thickness tailoring; they have a high photoluminescence quantum yield (up to 85%), colloidal and thermodynamic stability. Combined with surface modification that prevents degradation by water, this nanocrystalline material is an ideal candidate for optoelectronic devices and applications. In addition, optoelectronic measurements verify that the photodetector based on FAPbI3 nanocrystals paves the way for perovskite quantum dot photovoltaics.

  2. Structure modeling and growing AgClхBr1-х, Ag1-xTlxBr1-xIx, and Ag1-xTlxClyIzBr1-y-z crystals for infrared fiber optics

    NASA Astrophysics Data System (ADS)

    Korsakov, Alexandr; Zhukova, Liya; Korsakova, Elena; Zharikov, Evgenii

    2014-01-01

    In this paper we describe the aggregate technology of producing variable composition crystals, based on the solid solutions of silver and Tl+-doped halides for creating infrared photonic crystal fibers in the spectral range of 2-40 μm by extruding, we also produce all the necessary equipment. We specified the minimum melting point position for the AgCl-AgBr phase diagram. We also investigated the fundamental physical properties of new crystals and fibers: transmission losses, transmission range, refraction index, hardness, and density.

  3. Solution-based mist CVD technique for CH3NH3Pb(Br1- x Cl x )3 inorganic-organic perovskites

    NASA Astrophysics Data System (ADS)

    Nishinaka, Hiroyuki; Yoshimoto, Masahiro

    2016-10-01

    We report the growth of inorganic-organic perovskites using a solution-based mist chemical vapor deposition (mist CVD) technique and the successful growth of the alloying CH3NH3Pb(Br1- x Cl x )3 using mixture solutions of Br and Cl precursors. The formation mechanism of the inorganic-organic perovskite grown by the laminar flow-type mist CVD is suggested to be a vapor phase reaction, although solution precursors are used. The near-band-edge emissions from photoluminescence can be tuned from 500 to 550 nm by considering Br/Cl ratios in the solution without crystal phase segregation by incorporating Cl into crystalline CH3NH3PbBr3 films.

  4. Synthesis of a novel layered double hydroxides [MgAl(4)(OH)(12)](Cl)(2)·2.4H(2)O and its anion-exchange properties.

    PubMed

    Chitrakar, Ramesh; Makita, Yoji; Sonoda, Akinari; Hirotsu, Takahiro

    2011-01-30

    A novel layered double hydroxide of Mg and Al with composition [Mg(0.96)Al(4.00)(OH)(12)]Cl(1.86)(CO(3))(0.03)·2.4H(2)O, designated as MgAl(4)-Cl, was synthesized by mixing crystalline gibbsite (γ-Al(OH)(3)) and solid MgCl(2)·6H(2)O with subsequent hydrothermal treatment at 160 °C for 72h. The MgAl(4)-Cl exhibited a crystalline material of a layered structure, as evidenced from X-ray diffraction. Anion uptake experiments with the MgAl(4)-Cl showed that Cl(-) in the interlayer space can be exchanged with anions such as Br(-), H(2)PO(4)(-), CO(3)(2-) or dodecyl sulfate (DS(-)) from aqueous solutions with preservation of the layered structure. Uptake of NO(3)(-), BrO(3)(-) or SO(4)(2-) on the MgAl(4)-Cl showed different behavior; these anions can be exchanged within 1h maintaining the layered structure, but a release of Mg(2+) cations from the sample was observed with increased reaction time, resulting in collapse of the layered structure and formation of the gibbsite phase, as determined from chemical analyses and X-ray diffraction.

  5. Room-temperature and gram-scale synthesis of CsPbX3 (X = Cl, Br, I) perovskite nanocrystals with 50-85% photoluminescence quantum yields.

    PubMed

    Wei, Song; Yang, Yanchun; Kang, Xiaojiao; Wang, Lan; Huang, Lijian; Pan, Daocheng

    2016-05-26

    All inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (PNCs) with 50-85% photoluminescence quantum yields and tunable emission in the range of 440-682 nm have been successfully synthesized at room temperature in open air. This facile strategy enables us to prepare gram-scale CsPbBr3 NCs with a PLQY approaching 80%.

  6. Tracing recharge to aquifers beneath an Asian megacity with Cl/Br and stable isotopes: the example of Dhaka, Bangladesh

    NASA Astrophysics Data System (ADS)

    Hoque, M. A.; McArthur, J. M.; Sikdar, P. K.; Ball, J. D.; Molla, T. N.

    2014-06-01

    Dhaka, the capital of Bangladesh, is home to a population of 15 million people, whose water supply is 85% drawn from groundwater in aquifers that underlie the city. Values of Cl/Br >500 are common in groundwater beneath western Dhaka in areas <3 km from the river, and in rivers and sewers around and within the city. The study shows that groundwater beneath western Dhaka is strongly influenced by infiltration of effluent from leaking sewers and unsewered sanitation, and by river-bank infiltration from the Turag-Buriganga river system which bounds the western limit of the city. River-bank infiltration from other rivers around Dhaka is minor. Values of Cl/Br and Cl concentrations reveal that 23 % of wells sampled in Dhaka are influenced by saline connate water in amounts up to 1%. This residual natural salinity compromises the use of electrical conductivity of groundwater as a method for defining pathways of recharge by contaminated surface waters. Concentrations of As, B, Ba, Cd, Cu, F, Ni, NO3, Pb, Sb, Se and U in groundwater samples are less than WHO health-based guideline values for drinking water.

  7. What is the best bonding model of the (σ-H-BR) species bound to a transition metal? Bonding analysis in complexes [(H)2Cl(PMe3)2M(σ-H-BR)] (M = Fe, Ru, Os).

    PubMed

    Pandey, Krishna K

    2012-03-21

    Density Functional Theory calculations have been performed for the σ-hydroboryl complexes of iron, ruthenium and osmium [(H)(2)Cl(PMe(3))(2)M(σ-H-BR)] (M = Fe, Ru, Os; R = OMe, NMe(2), Ph) at the BP86/TZ2P/ZORA level of theory in order to understand the interactions between metal and HBR ligands. The calculated geometries of the complexes [(H)(2)Cl(PMe(3))(2)Ru(HBNMe(2))], [(H)(2)Cl(PMe(3))(2)Os(HBR)] (R = OMe, NMe(2)) are in excellent agreement with structurally characterized complexes [(H)(2)Cl(P(i)Pr(3))(2)Os(σ-H-BNMe(2))], [(H)(2)Cl(P(i)Pr(3))(2)Os{σ-H-BOCH(2)CH(2)OB(O(2)CH(2)CH(2))}] and [(H)(2)Cl(P(i)Pr(3))(2)Os(σ-H-BNMe(2))]. The longer calculated M-B bond distance in complex [(H)(2)Cl(PMe(3))(2)M(σ-H-BNMe(2))] are due to greater B-N π bonding and as a result, a weaker M-B π-back-bonding. The B-H2 bond distances reveal that (i) iron complexes contain bis(σ-borane) ligand, (ii) ruthenium complexes contain (σ-H-BR) ligands with a stretched B-H2 bond, and (iii) osmium complexes contain hydride (H2) and (σ-H-BR) ligands. The H-BR ligands in osmium complexes are a better trans-directing ligand than the Cl ligand. Values of interaction energy, electrostatic interaction, orbital interaction, and bond dissociation energy for interactions between ionic fragments are very large and may not be consistent with M-(σ-H-BR) bonding. The EDA as well as NBO and AIM analysis suggest that the best bonding model for the M-σ-H-BR interactions in the complexes [(H)(2)Cl(PMe(3))(2)M(σ-H-BR)] is the interaction between neutral fragments [(H)(2)Cl(PMe(3))(2)M] and [σ-H-BR]. This becomes evident from the calculated values for the orbital interactions. The electron configuration of the fragments which is shown for C in Fig. 1 experiences the smallest change upon the M-σ-H-BR bond formation. Since model C also requires the least amount of electronic excitation and geometry changes of all models given by the ΔE(prep) values, it is clearly the most appropriate choice of

  8. Incommensurate magnetic ordering in Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2} (X=Cl,Br) studied by single crystal neutron diffraction

    SciTech Connect

    Zaharko, O.; Roennow, H.; Mesot, J.; Crowe, S. J.; Paul, D. McK.; Brown, P. J.; Daoud-Aladine, A.; Meents, A.; Wagner, A.; Prester, M.; Berger, H.

    2006-02-01

    Polarized and unpolarized neutron-diffraction studies have been carried out on single crystals of the coupled spin tetrahedra systems Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2} (X=Cl,Br). A model of the magnetic structure associated with the propagation vectors k{sup '}{sub Cl}{approx_equal}(-0.150,0.422,(1/2)) and k{sup '}{sub Br}{approx_equal}(-0.172,0.356,(1/2)) and stable below T{sub N}=18 K for X=Cl and T{sub N}=11 K for X=Br is proposed. A feature of the model, common to both the bromide and chloride, is a canted coplanar motif for the four Cu{sup 2+} spins on each tetrahedron which rotates on a helix from cell to cell following the propagation vector. The Cu{sup 2+} magnetic moment determined for X=Br,0.395(5){mu}{sub B}, is significantly less than for X=Cl,0.88(1){mu}{sub B} at 2 K. The magnetic structure of the chloride associated with the wave vector k{sup '} differs from that determined previously for the wave vector k{approx_equal}(0.150,0.422,(1/2)) [O. Zaharko et al., Phys. Rev. Lett. 93, 217206(E) (2004)].

  9. Trace-element compositions and Br/Cl ratios of fluid inclusions in the Tsushima granite, Japan: Significance for formation of granite-derived fluids

    NASA Astrophysics Data System (ADS)

    Kurosawa, Masanori; Sasa, Kimikazu; Shin, Ki-Choel; Ishii, Satoshi

    2016-06-01

    Fluid inclusions in quartz samples from a miarolitic cavity, two quartz veins, and a hydrothermal ore vein in the Tsushima granite, Japan, were analyzed by particle-induced X-ray emission to examine the chemistry and process of formation of hydrothermal fluids in an island-arc granite. Most of the inclusions were polyphase or vapor, and there were smaller numbers of two-phase aqueous inclusions. The inclusions contained Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Ge, Br, Rb, Sr, Ba, and Pb. For each inclusion, there was a strong positive correlation between Cl content and contents of other elements identified. Concentration ranges for most elements (other than Rb and Ge) in polyphase inclusions from the miarolitic cavity were comparable to those from cavities in alkaline granites; those from the ore vein were comparable to large-scale continental hydrothermal ore deposits. The lower Rb and higher Ge contents in the polyphase inclusions of the Tsushima granite may be characteristic of hydrothermal fluids from calc-alkaline granites in an island-arc setting. Br/Cl ratios (by weight) for the vapor and two-phase inclusions were 0.0013-0.0030 and differed among the three geological settings. Br/Cl ratios of polyphase inclusions increased with increasing Cl content in single-crystal and polycrystalline quartz, and high values of more than 0.0100 were found. The high Br/Cl ratios and the differences among the geological settings sampled may be due to pressure dependences of partitioning of Cl and Br between fluid and magma during fluid segregation and between liquid and vapor during boiling. Using a simple model based on these dependences, we calculated Br/Cl ratios greater than 0.01 in brine generated at pressures <0.89 kbar. Differences in Br/Cl ratios in polyphase and vapor inclusions from each geological setting were attributed to mixing between two end-member fluids: a high Br/Cl fluid generated at low pressure and a low Br/Cl fluid generated at high pressure. Br/Cl ratios of

  10. Dihydroxyacetone (DHA) monomer complexes with CaBr2 and CdCl2.

    PubMed

    Rlepokura, Katarzyna; Lis, Tadeusz

    2008-03-01

    Two hydrated complexes of monomeric dihydroxyacetone (DHA; the simplest ketose), viz. the calcium bromide complex bis(mu-dihydroxyacetone)bis[tetraaquacalcium(II)] tetrabromide (isomorphous with the chloride compound reported previously), [Ca(2)(C(3)H(6)O(3))(2)(H(2)O)(8)]Br(4), (2e), and the cadmium chloride complex poly[[bis(mu-dihydroxyacetone)bis[bis(dihydroxyacetone)cadmium(II)

  11. Three-Dimensional BiOI/BiOX (X = Cl or Br) Nanohybrids for Enhanced Visible-Light Photocatalytic Activity.

    PubMed

    Liu, Yazi; Xu, Jian; Wang, Liqiong; Zhang, Huayang; Xu, Ping; Duan, Xiaoguang; Sun, Hongqi; Wang, Shaobin

    2017-03-14

    Three-dimensional flower-like BiOI/BiOX (X = Br or Cl) hybrids were synthesized via a facile one-pot solvothermal approach. With systematic characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET)specific surface area, X-ray photoelectron spectroscopy (XPS), and the UV-Vis diffuse reflectance spectra (DRS), the BiOI/BiOCl composites showed a fluffy and porous 3-D architecture with a large specific surface area (SSA) and high capability for light absorption. Among all the BiOX (X = Cl, Br, I) and BiOI/BiOX (X = Cl or Br) composites, BiOI/BiOCl stands out as the most efficient photocatalyst under both visible and UV light irradiations for methyl orange (MO) oxidation. The reaction rate of MO degradation on BiOI/BiOCl was 2.1 times higher than that on pure BiOI under visible light. Moreover, BiOI/BiOCl exhibited enhanced water oxidation efficiency for O₂ evolution which was 1.5 times higher than BiOI. The enhancement of photocatalytic activity could be attributed to the formation of a heterojunction between BiOI and BiOCl, with a nanoporous structure, a larger SSA, and a stronger light absorbance capacity especially in the visible-light region. The in situ electron paramagnetic resonance (EPR) revealed that BiOI/BiOCl composites could effectively evolve superoxide radicals and hydroxyl radicals for photodegradation, and the superoxide radicals are the dominant reactive species. The superb photocatalytic activity of BiOI/BiOCl could be utilized for the degradation of various industrial dyes under natural sunlight irradiation which is of high significance for the remediation of industrial wastewater in the future.

  12. On the chain lenth in Ox, HOx, NOx, ClOx and BrOx cycles in the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Larin, Igor; Kuskov, Michael

    2013-04-01

    Analysis of chain mechanisms of ozone depletion in Ox, HOx, NOx, ClOx and BrOx cycles has been performed. The carried out analysis has allowed to get analytical expression for calculation of the rate of limiting stage of chain prolongation, as well as chain breaking and chain length in cycles specified. It has been shown, that the correct estimation of ozone depletion in the chain processes is possible only through definition of the rate of limiting stage with taking into account of all reactions of chain prolongation, instead of the unique reaction possessing the least rate as it usually became earlier. It has been shown also, that choice of one reaction means ignoring a chain character of the process and leads to overestimate of real rate of ozone destruction. The role of null chain processes in the cycles specified above has been considered. It has been shown, that these processes play defining role in formation of families of odd oxygen, nitrogen, chlorine and bromine. By means of methods developed, data of IPCC scenario RCP 4.5, and two-dimensional model Socrates the rate of ozone destruction and chain length in Ox, HOx, NOx, ClOx and BrOx cycles for modeling conditions of April 2013 at 50 N and height diapason 15-120 km has been calculated. It has been shown, that in the middle stratosphere ozone destruction is due mainly to NOx cycle, whereas in the mesosphere and low thermosphere it is due mainly HOx one. It has been also shown that ClOx and BrOx have the greatest chain length in the upper stratosphere which exceeds 106 and HOx cycle in the low thermosphere has a chain length exceeding 1011.

  13. Three-Dimensional BiOI/BiOX (X = Cl or Br) Nanohybrids for Enhanced Visible-Light Photocatalytic Activity

    PubMed Central

    Liu, Yazi; Xu, Jian; Wang, Liqiong; Zhang, Huayang; Xu, Ping; Duan, Xiaoguang; Sun, Hongqi; Wang, Shaobin

    2017-01-01

    Three-dimensional flower-like BiOI/BiOX (X = Br or Cl) hybrids were synthesized via a facile one-pot solvothermal approach. With systematic characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET)specific surface area, X-ray photoelectron spectroscopy (XPS), and the UV-Vis diffuse reflectance spectra (DRS), the BiOI/BiOCl composites showed a fluffy and porous 3-D architecture with a large specific surface area (SSA) and high capability for light absorption. Among all the BiOX (X = Cl, Br, I) and BiOI/BiOX (X = Cl or Br) composites, BiOI/BiOCl stands out as the most efficient photocatalyst under both visible and UV light irradiations for methyl orange (MO) oxidation. The reaction rate of MO degradation on BiOI/BiOCl was 2.1 times higher than that on pure BiOI under visible light. Moreover, BiOI/BiOCl exhibited enhanced water oxidation efficiency for O2 evolution which was 1.5 times higher than BiOI. The enhancement of photocatalytic activity could be attributed to the formation of a heterojunction between BiOI and BiOCl, with a nanoporous structure, a larger SSA, and a stronger light absorbance capacity especially in the visible-light region. The in situ electron paramagnetic resonance (EPR) revealed that BiOI/BiOCl composites could effectively evolve superoxide radicals and hydroxyl radicals for photodegradation, and the superoxide radicals are the dominant reactive species. The superb photocatalytic activity of BiOI/BiOCl could be utilized for the degradation of various industrial dyes under natural sunlight irradiation which is of high significance for the remediation of industrial wastewater in the future. PMID:28336897

  14. Kinetics of the Reactions of O((sup 3)P) and Cl((sup 2)P) with HBr and Br2

    NASA Technical Reports Server (NTRS)

    Nicovich, J. M.; Wine, P. H.

    1997-01-01

    A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of reactions (1)-(4) as a function of temperature. (1) O((sup 3)P) + Br2 yields BrO + Br((sup 2)P(sub 3/2)) at 255-350 K; (2) Cl((sup 2)P) + Br2 yields BrCl + Br((sup 2)P(sub 3/2)) at 298-401 K; (3) O((sup 3)P) + HBr yields OH + Br((sup 2)P(sub J)) at 250-402 K; (4) Cl((sup 2)P) + HBr yields HCl + Br((sup 2)P(sub J)) at 257-404 K. In all cases, the concentration of the excess reagent, i.e, HBr or Br2, was measured in situ in the slow flow system by UV-visible photometry. Heterogeneous dark reactions between XBr (X equals H or Br) and the photolytic precursors for Cl((sup 2)P) and O((sup 3)P) (Cl2 and O3, respectively) were avoided by injecting minimal amounts of precursor into the reaction mixture immediately upstream from the reaction zone. The following Arrhenius expressions summarize our results (errors are 2 sigma and represent precision only, units are cu cm/(molecule.s): k(sub 1) = (1.76 +/- 0.80) x 10(exp -11 exp[(40 +/- 100)/T]; k(sub 2) = (2.40 +/- 1.25) x 12(exp -10) exp[-(144 +/- 176)/T]; k(sub 3) = (5.11 +/- 2.82) x 10(exp -12) exp[-(1450 +/- 160)/T]; k(sub 4) = (2.25 +/- 0.56) x 10(exp -11) exp[-(400 +/- 80)/T]. The consistency (or lack thereof) of our results with those reported in previous kinetics and dynamics studies of reactions (1)-(4) is discussed.

  15. In situ quantification of Br and Cl in minerals and fluid inclusions by LA-ICP-MS: a powerful tool to identify fluid sources

    USGS Publications Warehouse

    Hammerli, Johannes; Rusk, Brian; Spandler, Carl; Emsbo, Poul; Oliver, Nicholas H.S.

    2013-01-01

    Bromine and chlorine are important halogens for fluid source identification in the Earth's crust, but until recently we lacked routine analytical techniques to determine the concentration of these elements in situ on a micrometer scale in minerals and fluid inclusions. In this study, we evaluate the potential of in situ Cl and Br measurements by LA-ICP-MS through analysis of a range of scapolite grains with known Cl and Br concentrations. We assess the effects of varying spot sizes, variable plasma energy and resolve the contribution of polyatomic interferences on Br measurements. Using well-characterised natural scapolite standards, we show that LA-ICP-MS analysis allows measurement of Br and Cl concentrations in scapolite, and fluid inclusions as small as 16 μm in diameter and potentially in sodalite and a variety of other minerals, such as apatite, biotite, and amphibole. As a demonstration of the accuracy and potential of Cl and Br analyses by LA-ICP-MS, we analysed natural fluid inclusions hosted in sphalerite and compared them to crush and leach ion chromatography Cl/Br analyses. Limit of detection for Br is ~8 μg g−1, whereas relatively high Cl concentrations (> 500 μg g−1) are required for quantification by LA-ICP-MS. In general, our LA-ICP-MS fluid inclusion results agree well with ion chromatography (IC) data. Additionally, combined cathodoluminescence and LA-ICP-MS analyses on natural scapolites within a well-studied regional metamorphic suite in South Australia demonstrate that Cl and Br can be quantified with a ~25 μm resolution in natural minerals. This technique can be applied to resolve a range of hydrothermal geology problems, including determining the origins of ore forming brines and ore deposition processes, mapping metamorphic and hydrothermal fluid provinces and pathways, and constraining the effects of fluid–rock reactions and fluid mixing.

  16. Reaction of atomic bromine with acetylene and loss rate of atmospheric acetylene due to reaction with OH, Cl, O, and Br

    NASA Technical Reports Server (NTRS)

    Payne, W. A.; Nava, D. F.; Brunning, J.; Stief, L. J.

    1986-01-01

    The first-order, diffusion, and bimolecular rate constants for the reaction Br + C2H2 yields C2H3Br are evaluated. The rate constants are measured at 210, 248, 298, and 393 K and at pressures between 15-100 torr Ar using flash photolysis combined with time-resolved detection of atomic bromine via Br resonance radiation. It is observed that the reaction is not affected by pressure or temperature and the bimolecular constant = (4.0 + or - 0.8) x 10 to the -15th cu cm/sec with an error of two standard deviations. The C2H2 + Br reaction rates are compared with reactions of C2H2 with Cl, OH, NH2, and H. The loss rates for atmospheric C2H2 for reactions with OH, Cl, O, and Br are calculated as a function of altitude.

  17. Mutual neutralization of atomic rare-gas cations (Ne+, Ar+, Kr+, Xe+) with atomic halide anions (Cl-, Br-, I-)

    NASA Astrophysics Data System (ADS)

    Shuman, Nicholas S.; Miller, Thomas M.; Johnsen, Rainer; Viggiano, Albert A.

    2014-01-01

    We report thermal rate coefficients for 12 reactions of rare gas cations (Ne+, Ar+, Kr+, Xe+) with halide anions (Cl-, Br-, I-), comprising both mutual neutralization (MN) and transfer ionization. No rate coefficients have been previously reported for these reactions; however, the development of the Variable Electron and Neutral Density Attachment Mass Spectrometry technique makes it possible to measure the difference of the rate coefficients for pairs of parallel reactions in a Flowing Afterglow-Langmuir Probe apparatus. Measurements of 18 such combinations of competing reaction pairs yield an over-determined data set from which a consistent set of rate coefficients of the 12 MN reactions can be deduced. Unlike rate coefficients of MN reactions involving at least one polyatomic ion, which vary by at most a factor of ˜3, those of the atom-atom reactions vary by at least a factor 60 depending on the species. It is found that the rate coefficients involving light rare-gas ions are larger than those for the heavier rare-gas ions, but the opposite trend is observed in the progression from Cl- to I-. The largest rate coefficient is 6.5 × 10-8 cm3 s-1 for Ne+ with I-. Rate coefficients for Ar+, Kr+, and Xe+ reacting with Br2- are also reported.

  18. Mutual neutralization of atomic rare-gas cations (Ne(+), Ar(+), Kr(+), Xe(+)) with atomic halide anions (Cl(-), Br(-), I(-)).

    PubMed

    Shuman, Nicholas S; Miller, Thomas M; Johnsen, Rainer; Viggiano, Albert A

    2014-01-28

    We report thermal rate coefficients for 12 reactions of rare gas cations (Ne(+), Ar(+), Kr(+), Xe(+)) with halide anions (Cl(-), Br(-), I(-)), comprising both mutual neutralization (MN) and transfer ionization. No rate coefficients have been previously reported for these reactions; however, the development of the Variable Electron and Neutral Density Attachment Mass Spectrometry technique makes it possible to measure the difference of the rate coefficients for pairs of parallel reactions in a Flowing Afterglow-Langmuir Probe apparatus. Measurements of 18 such combinations of competing reaction pairs yield an over-determined data set from which a consistent set of rate coefficients of the 12 MN reactions can be deduced. Unlike rate coefficients of MN reactions involving at least one polyatomic ion, which vary by at most a factor of ∼3, those of the atom-atom reactions vary by at least a factor 60 depending on the species. It is found that the rate coefficients involving light rare-gas ions are larger than those for the heavier rare-gas ions, but the opposite trend is observed in the progression from Cl(-) to I(-). The largest rate coefficient is 6.5 × 10(-8) cm(3) s(-1) for Ne(+) with I(-). Rate coefficients for Ar(+), Kr(+), and Xe(+) reacting with Br2 (-) are also reported.

  19. Photoelectron imaging of atomic chlorine and bromine following photolysis of CH{sub 2}BrCl

    SciTech Connect

    Hua Linqiang; Shen Huan; Hu Changjin; Zhang Bing

    2008-12-28

    Photoionization of chlorine and bromine atoms following photodissociation of CH{sub 2}BrCl was studied in the wavelength range of 231-238 nm by photoelectron imaging technique. Final state-specific speed and angular distributions of the photoelectron were recorded. Analysis of relative branching ratios to different levels of Cl{sup +} and Br{sup +} revealed that the final ion level distributions are generally dominated by the preservation of the ion-core configuration of the intermediate resonant state. Some J{sub c} numbers of the intermediate states were newly assigned according to this regulation. The configuration interaction between resonant states and the autoionization in the continuum were also believed to play an important role in the ionization process since some ions that deviate from the regulation mentioned ahead were observed. The angular distributions of the electrons were found to be well characterized by {beta}{sub 2} and {beta}{sub 4}, although the ionization process of chlorine and bromine atoms involves three photons.

  20. Decolorization of Blue CL-BR dye by AOPs using bleach wastewater as source of H2O2.

    PubMed

    Yasar, Abdullah; Ahmad, Nasir; Khan, Aamir Amanat Ali; Yousaf, Anwer

    2007-01-01

    This research was focused on the investigation of the efficacy of advanced oxidation processes (Fenton, ozonation and UV/H2O2) for decolorization of reactive azo dye (Blue CL-BR) using bleach wastewater as possible source of H202. All the experiments were performed on the laboratory scale set-up. The results showed that colour removal efficiencies by UV or bleach (H2O2) alone were not so efficient. Fenton process with bleach wastewater was found to be the most effective at process conditions such as pH of 3 and H2O2/Fe2+ ratio of 24:1, resulting in 64% colour removal. Almost complete colour removal, i.e., 99% and 95% were achieved by UV/H2O2 and UV/bleach wastewater in 30 and 60 min, respectively. Ozonation proved an efficient method for decolorization of Blue CL-BR dye at alkaline pH. It was possible to achieve 98% colour removal with 30 min of ozonation at pH 9. The colour removal of dye was found to follow first order kinetics.

  1. Vibrational spectra and nonlinear optical coefficients of rhombohedral CsGe X3 halide compounds with X =I , Br, Cl

    NASA Astrophysics Data System (ADS)

    Huang, Ling-yi; Lambrecht, Walter R. L.

    2016-09-01

    The zone-center phonons are calculated for rhombohedral CsGe X3 compounds with X =I , Br, Cl using density functional perturbation theory in a plane-wave pseudopotential method. The infrared absorption and reflection spectra are simulated and show that the absorption has a strong contribution from the LO as well as TO modes. Both the lowest and highest IR active modes have strong oscillator strengths for each symmetry (A1 and E ) and correspond to motions of either the Cs or Ge ions relative to the halogen ions. respectively. The intermediate modes have low oscillator strength because their mode pattern shows less clearly a dipole pattern. The polarization dependent Raman spectra for various backscattering configurations are simulated. Only the highest modes of each symmetry have a strong Raman intensity. The results for the Raman spectra are found to be in good agreement with the available experimental data for polycrystalline films when averaging over directions. The Born effective charges and high and low frequency dielectric tensors as well as the second-order nonlinear optical coefficients are calculated. The ratio of the static to the high-frequency dielectric constants are extremely high and analyzed in terms of the contribution of each mode to the Lyddane-Sachs-Teller relation. The nonlinear optical coefficients decrease strongly from I to Br to Cl in reverse order of the band gaps and are found to be consistent with available experimental results.

  2. A scaled quantum mechanical force field for the sulfuryl halides. I. The symmetric halides SO2X2 (X=F, Cl, Br).

    PubMed

    Fernández, L E; Verón, M G; Varetti, E L

    2004-01-01

    Force fields and vibrational wavenumbers were calculated for the molecules SO2X2 (X=F, Cl, Br) using DFT techniques. The previously available experimental data and assignments for SO2F2 and SO2Cl2 were compared with the theoretical results and revised, and new low temperature infrared and Raman data were obtained for SO2Cl2. These data were subsequently used in the definition of scaled quantum mechanics force fields for such molecules. Adjusted wavenumbers were also predicted for the still unknown SO2Br2. A comparison is made with results published for the VO2X2- anions.

  3. A scaled quantum mechanical force field for the sulfuryl halides. I. The symmetric halides SO 2X 2 (X=F, Cl, Br)

    NASA Astrophysics Data System (ADS)

    Fernández, L. E.; Verón, M. G.; Varetti, E. L.

    2004-01-01

    Force fields and vibrational wavenumbers were calculated for the molecules SO 2X 2 (X=F, Cl, Br) using DFT techniques. The previously available experimental data and assignments for SO 2F 2 and SO 2Cl 2 were compared with the theoretical results and revised, and new low temperature infrared and Raman data were obtained for SO 2Cl 2. These data were subsequently used in the definition of scaled quantum mechanics force fields for such molecules. Adjusted wavenumbers were also predicted for the still unknown SO 2Br 2. A comparison is made with results published for the VO 2X 2- anions.

  4. Estudio comparativo de las moléculas isovalentes de interés atmosférico CF3Cl y CF3Br y sus correspondientes halógenos aislados Cl y Br.

    NASA Astrophysics Data System (ADS)

    Mayor, E.; Velasco, A. M.; Martín, I.; Lavín, C.

    Los estados Rydberg moleculares han suscitado en los últimos años un creciente interés entre los espectroscopistas experimentales, motivado en parte por el desarrollo de nuevas técnicas espectroscópicas capaces de investigar estos estados altamente excitados electrónicamente. Los procesos de fotoabsorción que implican estados Rydberg en los derivados halogenados del metano son de gran importancia, debido a su abundancia en la atmósfera y a sus implicaciones medioambientales. Por ello, la obtención de datos relativos a sus fuerzas de oscilador es de gran interés. En este trabajo se aborda el estudio de dichas propiedades para las moléculas isovalentes CF3Cl y CF3Br. Ambas moléculas presentan idéntica estructura electrónica para el estado fundamental por lo que se espera que sus espectros Rydberg presenten grandes similitudes, en ausencia de perturbaciones. Por ello y dada la escasez de datos relativos a fuerzas de oscilador, hemos establecido la corrección de nuestros resultados en base a las analogías esperadas en las intensidades espectrales correspondientes a transiciones análogas. Por otro lado, Novak y col. [1] han encontrado experimentalmente un marcado carácter atómico en el espectro correspondiente a estas moléculas, siendo muy similar a los de los átomos de Cl y Br. Por ello en el presente trabajo, además de establecer la comparación entre ambas moléculas hemos buscado las similitudes con sus respectivos halógenos. Los cálculos relativos a las especies moleculares se han realizado utilizando la Metodología Molécular de Orbítales de Defecto Cuántico (MQDO) [2], mientras que para el estudio de los átomos de Cl y Br se empleó la versión relativista del método (RQDO) [3].

  5. Simultaneously promoting charge separation and photoabsorption of BiOX (X = Cl, Br) for efficient visible-light photocatalysis and photosensitization by compositing low-cost biochar

    NASA Astrophysics Data System (ADS)

    Li, Min; Huang, Hongwei; Yu, Shixin; Tian, Na; Dong, Fan; Du, Xin; Zhang, Yihe

    2016-11-01

    Exploration of novel and efficient composite photocatalysts is of great significance for advancing the practical application of photocatalysis. BiOX (X = Cl, Br) is a kind of promising photocatalysts, but the charge separation efficiency and photoabsorption need to be ameliorated. In this work, we first employ a low-cost and easily accessable carbon material biochar to modify BiOX (X = Cl, Br) and develop biochar/BiOX (X = Cl, Br) composite photocatalysts via a facile in-situ deposition method. The as-prepared composites are detailedly characterized by SEM, SEM-mapping, TEM, XRD and XPS, and DRS result demonstrates that the visible-light absorption of BiOX (X = Cl, Br) catalysts can be exceedingly enhanced by biochar. The biochar/BiOX (X = Cl, Br) composites are found to unfold remarkably enhanced visible-light-driven photocatalytic activity toward degradation of MO and photocurrent generation. The strengthened photocatalytic performance mainly stems from the profoundly improved charge separation and delivery efficiency, as evidenced by the electrochemical impedance spectra (EIS), photoluminescence (PL), and time-resolved PL decay spectra. Additionally, the biochar exerts importance in enhancing the two different types of photochemical reactions of BiOBr and BiOCl, in which the photocatalytic mechanisms are found to be photocatalysis and photosensitization process, respectively. The present work may open up a new avenue for framing economic and efficient photocatalytic materials and new composite materials for photoelectric application.

  6. A High Resolution Phoswich Detector: LaBr3(Ce) Coupled With LaCl3(Ce)

    NASA Astrophysics Data System (ADS)

    Carmona-Gallardo, M.; Borge, M. J. G.; Briz, J. A.; Gugliermina, V.; Perea, A.; Tengblad, O.; Turrión, M.

    2010-04-01

    An innovative solution for the forward end-cap CALIFA calorimeter of R3B is under investigation consisting of two scintillation crystals, LaBr3 and LaCl3, stacked together in a phoswich configuration with one readout only. This dispositive should be capable of a good determination of the energy of protons and gamma radiation. This composite detector allows to deduce the initial energy of charged particles by ΔE1+ΔE2 identification. For gammas, the simulations show that there is a high probability that the first interaction occurs inside the scintillator at few centimeters, with a second layer, the rest of the energy is absorbed, or it can be used as veto event in case of no deposition in the first layer. One such a detector has been tested at the Centro de MicroAnálisis de Materiales (CMAM) in Madrid. Good resolution and time signal separation have been achieved.

  7. Electrochemical and Spectroscopic Behaviors of 1-(o-, m-, p- Cl, or Br) Substituted Phenyl-3, 5-diphenylformazans in Dimethyl Sulfoxide.

    PubMed

    Tezcan, Habibe; Ekmekci, Güler

    2010-03-01

    1-(o-, m-, p-Cl, -Br) substituted phenyl-3, 5-diphenylformazans were synthesized. Their structures were elucidated and spectral behaviours were investigated by elemental analysis, FT-IR, UV-vis spectral data. The electrochemical properties such as number of electrons transferred (n), diffusion coefficient (D) and heterogeneous rate constant (ks) were determined and possible mechanisms were proposed using platinum and ultramicro platinum electrodes, cyclic voltammetry, linear sweep voltammetry and chronoamperometry. The oxidations were carried out at different electrochemical steps that were dependent upon the structure of formazans. The relation between their absorption properties with electrochemical properties was investigated. A suitable correlation was obtained between the absorption λmax with electrochemical properties, and between the oxidation peak potentials Eox1 with ks values of formazans.

  8. Relativistic effects on the aromaticity of the halogenated benzenes: C6X6, X = H, F, Cl, Br, I, At.

    PubMed

    Ramírez-Tagle, Rodrigo; Alvarado-Soto, Leonor; Villavicencio-Wastavino, Andrés; Alvarez-Thon, Luis

    2016-09-28

    In this study we report about the relativistic effects on the aromaticity of the six hexahalogenated compounds (C6H6, C6F6, C6Cl6, C6Br6, C6I6 and C6At6), via a magnetically induced current density method. All-electron density functional theory (DFT) calculations were carried out using the four-component Dirac-Coulomb (DC) Hamiltonian, including scalar and spin-orbit (SO) relativistic effects. Fully relativistic values of the magnetically induced ring currents were obtained by numerical integration over the current flow. These values were compared to the spin-free (SO interaction switched off) and non-relativistic values, in order to assess the corresponding contributions to aromaticity. It was found that in C6I6 and C6At6 there is a strong SO influence, in line with the expected relativistic effects of the heavy elements, iodine and astatine.

  9. ClONO and BrONO loss mechanisms in the presence of NO 2: A quantum-mechanical study

    NASA Astrophysics Data System (ADS)

    Lesar, A.; Kovačič, S.; Hodošček, M.

    2006-10-01

    The structural properties of the transition states for XONO (X = Cl, Br) loss in the presence of NO 2 are examined by the use of B3LYP density functional theory with various basis sets. The energetics were refined with CBS-QB3 calculations. The energy barriers for reaction channels leading to XNO 2 + NO 2 are estimated to be 4.1 and 3.1 kcal mol -1 for the chlorine and bromine reaction, respectively, whereas for the XONO 2 + NO products the energy barriers of 22.4 and 24.9 kcal mol -1, respectively, were found. These results suggest that the isomerization of XONO → XNO 2 is significantly facilitated in the presence of NO 2 compared to the corresponding unimolecular isomerizations.

  10. Ferroelectric properties of the [N(CH3)4]2CoCl2Br2 compound

    NASA Astrophysics Data System (ADS)

    Ben Rhaiem, Abdallah; Jomni, Fathi; Karoui, Karim; Guidara, Kamel

    2013-03-01

    Synthesis, X-ray powder and Raman description are reported for [N(CH3)4]2CoCl2Br2 compound. The calorimetric study shows three endothermic peaks at 289 K, 323 K and 408 K. The compound crystallizes in the orthorhombic system, space group Pnma with a = 12.384 Å, b = 9.058 Å and c = 15.647 Å. The dielectric spectra were measured in the frequency range 10-1-106 Hz and temperature interval from 200 to 305 K. The dielectric permittivity shows that this compound exhibits a ferroelectric-paraelectric phase transition at 290 K. The frequency dependent permittivity is interpreted in the non-Debye model. The temperature dependence of the low frequency limit of the bulk AC conductivity σdc is well described by the Arrhenius equation: σdc = σ0 exp(-Ea/kT).

  11. Resonances in SN2 reactions: Two-mode quantum calculations for Cl-+CH3Br on a coupled-cluster potential energy surface

    NASA Astrophysics Data System (ADS)

    Schmatz, Stefan; Botschwina, Peter; Hauschildt, Jan; Schinke, Reinhard

    2002-12-01

    An effective two-dimensional potential energy surface has been constructed for the SN2 reaction Cl-+CH3Br→ClCH3+Br- from coupled-cluster calculations with a large basis set. In the quantum dynamics calculations Radau coordinates were employed to describe the Cl-C and C-Br stretching modes. Making use of the filter diagonalization method and an optical potential, bound states as well as resonance states up to energies far above the dissociation threshold have been calculated. The resonance widths fluctuate over several orders of magnitude. In addition to a majority of Feshbach-type resonances there are also exceedingly long-lived shape resonances, which can only decay by tunneling. Owing to a smaller width of the potential barrier and a larger density of states, tunneling through the barrier is more important for Cl-+CH3Br than for Cl-+CH3Cl despite the larger total mass of this system. Excitation of the C-Br stretching vibration enhances the tunneling probability of the entrance channel complex.

  12. Chlorine isotope and Cl-Br fractionation in fluids of Poás volcano (Costa Rica): Insight into an active volcanic-hydrothermal system

    NASA Astrophysics Data System (ADS)

    Rodríguez, Alejandro; Eggenkamp, H. G. M.; Martínez-Cruz, María; van Bergen, Manfred J.

    2016-10-01

    Halogen-rich volcanic fluids issued at the surface carry information on properties and processes operating in shallow hydrothermal systems. This paper reports a long-term record of Cl-Br concentrations and δ37Cl signatures of lake water and fumaroles from the active crater of Poás volcano (Costa Rica), where surface expressions of magmatic-hydrothermal activity have shown substantial periodic changes over the last decades. Both the hyperacid water of its crater lake (Laguna Caliente) and subaerial fumaroles show significant temporal variability in Cl-Br concentrations, Br/Cl ratios and δ37Cl, reflecting variations in the mode and magnitude of volatile transfer. The δ37Cl signatures of the lake, covering the period 1985-2012, show fluctuations between + 0.02 ± 0.06‰ and + 1.15 ± 0.09‰. Condensate samples from adjacent fumaroles on the southern shore, collected during the interval (2010-2012) with strong changes in gas temperature (107-763°C), display a much larger range from - 0.43 ± 0.09‰ to + 14.09 ± 0.08‰. Most of the variations in Cl isotope, Br/Cl and concentration signals can be attributed to interaction between magma-derived gas and liquid water in the volcanic-hydrothermal system below the crater. The δ37Cl were lowest and closest to magmatic values in (1) fumarolic gas that experienced little or no interaction with subsurface water and followed a relatively dry pathway, and (2) water that captured the bulk of magmatic halogen output so that no phase separation could induce fractionation. In contrast, elevated δ37Cl can be explained by partial scavenging and fractionation during subsurface gas-liquid interaction. Hence, strong Cl isotope fractionation leading to very high δ37Cl in Poás' fumaroles indicates that they followed a wet pathway. Highest δ37Cl values in the lake water were found mostly in periods when it received a significant input from subaqueous fumaroles or when high temperatures and low pH caused HCl evaporation. It is

  13. Coordination Chemistry of Diiodine and Implications for the Oxidation Capacity of the Synergistic Ag(+) /X2 (X=Cl, Br, I) System.

    PubMed

    Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

    2016-08-01

    The synergistic Ag(+) /X2 system (X=Cl, Br, I) is a very strong, but ill-defined oxidant-more powerful than X2 or Ag(+) alone. Intermediates for its action may include [Agm (X2 )n ](m+) complexes. Here, we report on an unexpectedly variable coordination chemistry of diiodine towards this direction: (A)Ag-I2 -Ag(A), [Ag2 (I2 )4 ](2+) (A(-) )2 and [Ag2 (I2 )6 ](2+) (A(-) )2 ⋅(I2 )x≈0.65 form by reaction of Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) with diiodine (single crystal/powder XRD, Raman spectra and quantum-mechanical calculations). The molecular (A)Ag-I2 -Ag(A) is ideally set up to act as a 2 e(-) oxidant with stoichiometric formation of 2 AgI and 2 A(-) . Preliminary reactivity tests proved this (A)Ag-I2 -Ag(A) starting material to oxidize n-C5 H12 , C3 H8 , CH2 Cl2 , P4 or S8 at room temperature. A rough estimate of its electron affinity places it amongst very strong oxidizers like MF6 (M=4d metals). This suggests that (A)Ag-I2 -Ag(A) will serve as an easily in bulk accessible, well-defined, and very potent oxidant with multiple applications.

  14. Influence of incommensurate modulation on the optical properties of the solid solution ((CH3)4N)2ZnCl2.8Br1.2

    NASA Astrophysics Data System (ADS)

    Kremers, M.; Meekes, H.

    1996-08-01

    This paper reports on measurements with a high-accuracy universal polarimeter of the birefringence, optical activity, and indicatrix rotation in incommensurately modulated ((CH3)4N)2ZnCl2.8Br1.2 crystals. It is shown that in this solid solution the inversion symmetry is broken already in the paraelastic phase, due to the inhomogeneous distribution of Cl and Br over the zinc-halide tetrahedra. This, however, allows one to study the influence of the incommensurate modulation on a nonzero optical activity. This influence is clearly shown for a sample in which, moreover, the modulation wave vector is believed to lock at several commensurate values.

  15. Structural and energetic properties of closed shell XF(n) (X = Cl, Br, and I; n = 1-7) and XO(n)F(m) (X = Cl, Br, and I; n = 1-3; m = 0-6) molecules and ions leading to stability predictions for yet unknown compounds.

    PubMed

    Thanthiriwatte, K Sahan; Vasiliu, Monica; Dixon, David A; Christe, Karl O

    2012-10-15

    Atomization energies at 0 K and heats of formation at 0 and 298 K were predicted for the closed shell compounds XF, XF(2)(-), XF(2)(+), XF(3), XF(4)(-), XF(4)(+), XF(5), XF(6)(-), XF(6)(+) (X = Cl and Br) and XO(+), XOF, XOF(2)(-), XOF(2)(+), XOF(3), XOF(4)(-), XOF(4)(+), XOF(5), XOF(6)(-), XO(2)(+), XO(2)F, XO(2)F(2)(-), XO(2)F(2)(+), XO(2)F(3), XO(2)F(4)(-), XO(3)(+), XO(3)F, XO(3)F(2)(-) (X = Cl, Br, and I) using a composite electronic structure approach based on coupled cluster CCSD(T) calculations extrapolated to the complete basis set limit with additional corrections. The calculated heats of formation are in good agreement with the available experimental data. The calculated heats of formation were used to predict fluoride affinities, fluorine cation affinities, and F(2) binding energies. On the basis of our results, BrOF(5) and BrO(2)F(3) are predicted to be stable against spontaneous loss of F(2) and should be able to be synthesized, whereas BrF(7), ClF(7), BrOF(6)(-), and ClOF(6)(-) are unstable by a very wide margin. The stability of ClOF(5) is a borderline case. Although its F(2) loss is predicted to be exothermic by 4.4 kcal/mol, it may have a sufficiently large barrier toward decomposition and be preparable. This situation would resemble ClO(2)F(3) which was successfully synthesized in spite of being unstable toward F(2) loss by 3.3 kcal/mol. On the other hand, the ClOF(4)(+) and BrOF(4)(+) cations are less likely to be preparable with F(2) loss exothermicities of -17.5 and -9.3 kcal/mol, respectively. On the basis of the F(-) affinities of ClOF (45.4 kcal/mol), BrOF (58.7 kcal/mol), and BrO(2)F(3) (65.7 kcal/mol) and their predicted stabilities against loss of F(2), the ClOF(2)(-), BrOF(2)(-), and BrO(2)F(4)(-) anions are excellent targets for synthesis. Our previous failure to prepare the ClO(2)F(4)(-) anion can be rationalized by the predicted high exothermicity of -17.4 kcal/mol for the loss of F(2).

  16. Electrolytic LiCl precipitation from LiCl-KCl melt in porous Li-Al anodes

    SciTech Connect

    Vallet, C.E.; Heatherly, D.E.; Heatherly, L. Jr.; Braunstein, J.

    1983-12-01

    Composition gradients such as those predicted to occur during discharge of porous Li-Al negative electrodes of Li/S batteries with LiCl-KCl eutectic electrolyte were generated and measured in the LiCl-KCl anolyte of an electrolysis cell with Li-Al electrodes. Precipitation of lithium chloride during electrolysis was observed by two-dimensional scanning of electrolyte composition in the front part of quenched porous Li-Al anode sections using SEM/EDX. The distribution of sites of increased or decreased LiCl concentration, LiCl saturation and precipitation was mapped. Cathodic regions were observed near the cell walls. Preliminary results of analysis by Auger spectroscopy confirm LiCl precipitation in the porous anode. 16 references, 7 figures, 1 table.

  17. Electrolytic LiCl precipitation from LiCl-KCl melt in porous Li-Al anodes

    NASA Astrophysics Data System (ADS)

    Vallet, C. E.; Heatherly, D. E.; Heatherly, L., Jr.; Braunstein, J.

    1983-12-01

    Composition gradients such as those predicted to occur during discharge of porous Li-Al negative electrodes of Li/S batteries with LiCl-KCl eutectic electrolyte were generated and measured in the LiCl-KCl anolyte of an electrolysis cell with Li-Al electrodes. Precipitation of lithium chloride during electrolysis was observed by two-dimensional scanning of electrolyte composition in the front part of quenched porous Li-Al anode sections using SEM/EDX. The distribution of sites of increased or decreased LiCl concentration, LiCl saturation and precipitation was mapped. Cathodic regions were observed near the cell walls. Preliminary results of analysis by Auger spectroscopy confirm LiCl precipitation in the porous anode.

  18. Interaction of water with LiCl, LiBr, and LiI in the deeply supercooled region.

    PubMed

    Souda, Ryutaro

    2007-12-07

    The hydration mechanism of lithium halides was studied using time-of-flight secondary ion mass spectrometry as a function of temperature. The lithium halides embedded in thin films of amorphous solid water segregate to the surface at temperatures higher than 135-140 K, with efficiency increasing in the order of LiCl, LiBr, and LiI. A monolayer of LiCl and LiI adsorbed on the surface of amorphous solid water tends to diffuse into the bulk at 160 K. The infrared absorption band revealed that the aqueous lithium-halide solutions and crystals are formed simultaneously at 160 K; these phenomena are explicable as a consequence of the evolution of supercooled liquid water. The strong surfactant effect is inferred to arise from hydration of a contact ion pair having hydrophilic (lithium) and hydrophobic (halide) moieties. Furthermore, bulk diffusion of lithium halides might result from the formation of a solvent-separated ion pair in supercooled liquid water. The presence of two liquid phases of water with different local structures is probably responsible for the formation of these two hydrates, consistent with the calculated result reported by Jungwirth and Tobias[J. Phys. Chem. B 106, 6361 (2002)].

  19. Four-mode quantum calculations of resonance states in complex-forming bimolecular reactions: Cl-+CH3Br

    NASA Astrophysics Data System (ADS)

    Schmatz, Stefan

    2005-06-01

    The vibrational resonance states of the complexes formed in the nucleophilic bimolecular substitution (SN2) reaction Cl-+CH3Br→ClCH3+Br- were calculated by means of the filter diagonalization method employing a coupled-cluster potential-energy surface and a Hamiltonian that incorporates an optical potential and is formulated in Radau coordinates for the carbon-halogen stretching modes. The four-dimensional model also includes the totally symmetric vibrations of the methyl group (C-H stretch and umbrella bend). The vast majority of bound states and many resonance states up to the first overtone of the symmetric stretching vibration in the exit channel complex have been calculated, analyzed, and assigned four quantum numbers. The resonances are classified into entrance channel, exit channel, and delocalized states. The resonance widths fluctuate over six orders of magnitude. In addition to a majority of Feshbach-type resonances there are also exceedingly long-lived shape resonances, which are associated with the entrance channel and can only decay by tunneling. The state-selective decay of the resonances was studied in detail. The linewidths of the resonances, and thus the coupling to the energetic continuum, increase with excitation in any mode. Due to the strong mixing of the many progressions in the intermolecular stretching modes of the intermediate complexes, this increase as a function of the corresponding quantum numbers is not monotonic, but exhibits pronounced fluctuations.

  20. Electronic and optical properties of MAPbX3 perovskites (X = I, Br, Cl): a unified DFT and GW theoretical analysis.

    PubMed

    Mosconi, Edoardo; Umari, Paolo; De Angelis, Filippo

    2016-10-05

    Materials engineering is a key for the enhancement of photovoltaics technology. This is particularly true for the novel class of perovskite solar cells. Accurate theoretical modelling can help establish general trends of behavior when addressing structural changes. Here, we consider the effects due to halide substitution in organohalide CH3NH3PbX3 perovskites exploring the halide series with X = Cl, Br, I. For this task, we use accurate DFT and GW methods including spin-orbit coupling. We find the expected band gap increase when moving from X = I to Cl, in line with the experimental data. Most notably, the calculated absorption coefficients for I, Br and Cl are nicely reproducing the behavior reported experimentally. A common feature of all the simulated band structures is a significant Rashba effect. This is similar for MAPbI3 and MAPbBr3 while MAPbCl3 shows in general a reduced Rashba interaction coefficient. Finally, a monotonic increase of the exciton reduced masses is calculated when moving from I to Br to Cl, in line with the stronger excitonic character of the lighter perovskite halides.

  1. Ring-strain release in neutral and dicationic 7,8,17,18-tetra­bromo-5,10,15,20-tetra­phenyl­porphyrin: crystal structures of C44H26Br4N4 and C44H28Br4N4 2+·2ClO4 −·3CH2Cl2

    PubMed Central

    Scheidt, W. Robert; Duval, Hugues F.; Oliver, Allen G.

    2016-01-01

    Two porphyrin complexes were studied to determine the effects of protonation on ring deformation within the porphyrin. The porphyrin 7,8,17,18-tetra­bromo-5,10,15,20-tetra­phenyl­porphyrin, C44H26Br4N4, was selected because the neutral species is readily doubly protonated to yield a dication, which was crystallized here with perchlorate counter-ions as a di­chloro­methane tris­olvate, C44H28Br4N4 2+·2ClO4 −·3CH2Cl2. The centrosymmetric neutral species is observed to have a mild ‘ruffling’ of the pyrrole rings and is essentially planar throughout; intra­molecular N—H⋯N hydrogen bonds occur. In contrast, the dication exhibits considerable deformation, with the pyrrole rings oriented well out of the plane of the porphyrin, resulting in a ‘saddle’ conformation of the ring. The charged species forms N—H⋯O hydrogen bonds to the perchlorate anions, which lie above and below the plane of the porphyrin ring. Distortions to the planarity of the pyrrole rings in both cases are very minor. The characterization of the neutral species represents a low-temperature redetermination of the previous room-temperature analyses [Zou et al. (1995 ▸). Acta Cryst. C51, 760–761; Rayati et al. (2008 ▸). Polyhedron, pp. 2285–2290], which showed disorder and physically unrealistic displacement parameters. PMID:27308051

  2. Crystal structure, thermal, electric and magnetic study of [(CH2)7(NH3)2]CoCl2Br2

    NASA Astrophysics Data System (ADS)

    Mostafa, M. F.; Abd-elal, S.; Tammam, A. K.

    2014-01-01

    1,7-Heptanediammonium-dichlorodibromo-cobaltate (II), with molecular formula [(CH2)7(NH3)2]CoCl2Br2, has been synthesized. It is triclinic {{P}}bar{1} , a = 7.4042 (4) Å, b = 10.3484 (5) Å, c = 11.3554 (6) Å, α = 66.289 (3)° β = 78.425 (2)°, γ = 86.546 (3)°. Its crystal structure contains distorted tetrahedral [CoCl2Br2]2- anions and zigzag [(CH2)7(NH3)2]2+ cations which are connected via a network of hydrogen bonds. The largest difference in Co-Cl and Co-Br bond lengths are 0.081 Å and largest difference in Br-Co-Cl angles is 8.1°. The compound has been studied by thermal analysis, impedance spectroscopy and magnetic susceptibility. Thermal studies show three phase transitions at T 1 = 378 K, T 2 = 355 K, associated with solid-solid phase change and T 3 = 333.8 K ascribed to chain conformation and reorientation. Permittivity and ac conductivity as a function of temperature (300-395 K) and frequency (0.06 kHz < f < 100 kHz) is presented. AC conductivity is thermally activated in different phases. Conduction is mainly due to Cl- and Br- ion hopping in the high temperature range. Magnetic susceptibility yields an effective magnetic moment μ eff = 4.43 BM and Curie-Weiss temperature, Θ = -4.7 K which confirm tetragonal symmetry of [CoCl4]2- and weak antiferromagnetic interaction at low temperatures.

  3. Thermal and electrochemical C-X activation (X = Cl, Br, I) by the strong Lewis acid Pd3(dppm)3(CO)2+ cluster and its catalytic applications.

    PubMed

    Lemaître, Frédéric; Lucas, Dominique; Groison, Katherine; Richard, Philippe; Mugnier, Yves; Harvey, Pierre D

    2003-05-07

    The stoichiometric and catalytic activations of alkyl halides and acid chlorides by the unsatured Pd(3)(dppm)(3)(CO)(2+) cluster (Pd(3)(2+)) are investigated in detail. A series of alkyl halides (R-X; R = t-Bu, Et, Pr, Bu, allyl; X = Cl, Br, I) react slowly with Pd(3)(2+) to form the corresponding Pd(3)(X)(+) adduct and "R(+)". This activation can proceed much faster if it is electrochemically induced via the formation of the paramagnetic species Pd(3)(+). The latter is the first confidently identified paramagnetic Pd cluster. The kinetic constants extracted from the evolution of the UV-vis spectra for the thermal activation, as well as the amount of electricity to bring the activation to completion for the electrochemically induced reactions, correlate the relative C-X bond strength and the steric factors. The highly reactive "R(+)" species has been trapped using phenol to afford the corresponding ether. On the other hand, the acid chlorides react rapidly with Pd(3)(2+) where no induction is necessary. The analysis of the cyclic voltammograms (CV) establishes that a dissociative mechanism operates (RCOCl --> RCO(+) + Cl(-); R = t-Bu, Ph) prior to Cl(-) scavenging by the Pd(3)(2+) species. For the other acid chlorides (R = n-C(6)H(13), Me(2)CH, Et, Me, Pr), a second associative process (Pd(3)(2+) + RCOCl --> Pd(3)(2+.....)Cl(CO)(R)) is seen. Addition of Cu(NCMe)(4)(+) or Ag(+) leads to the abstraction of Cl(-) from Pd(3)(Cl)(+) to form Pd(3)(2+) and the insoluble MCl materials (M = Cu, Ag) allowing to regenerate the starting unsaturated cluster, where the precipitation of MX drives the reaction. By using a copper anode, the quasi-quantitative catalytic generation of the acylium ion ("RCO(+)") operates cleanly and rapidly. The trapping of "RCO(+)" with PF(6)(-) or BF(4)(-) leads to the corresponding acid fluorides and, with an alcohol (R'OH), to the corresponding ester catalytically, under mild conditions. Attempts were made to trap the key intermediates "Pd(3)(Cl

  4. Syntheses and reactivities of stable halosilylenoids, (Tsi)X2SiLi (Tsi=C(SiMe3)3, X=Br, Cl).

    PubMed

    Lee, Myong Euy; Cho, Hyeon Mo; Lim, Young Mook; Choi, Jin Kyong; Park, Chang Hee; Jeong, Seong Eun; Lee, Uk

    2004-01-23

    Halosilylenoids, stable at room temperature (Tsi)X(2)SiLi (Tsi=C(SiMe(3))(3), X=Br, Cl), were synthesized from the reaction of TsiSiX(3) with lithium naphthalenide. Bromosilylenoid reacted with tBuOH and MeI both at -78 degrees C and at room temperature to give (Tsi)HSiBr(2) and (Tsi)MeSiBr(2), respectively, in high yields; this clearly shows its nucleophilicity. In the reaction of bromosilylenoid with methanol, 2-propanol, and 2,3-dimethyl-1,3-butadiene, the corresponding products, (Tsi)HSi(OMe)(2), (Tsi)HSi(OiPr)Br, and bromo(Tsi)silacyclopent-3-ene, were obtained in high yields; this demonstrates its amphiphilic property, as if bromosilylene would be trapped. Chlorosilylenoid also exhibited both nucleophilic and amphiphilic properties. The (29)Si chemical shifts for (Tsi)Br(2)SiLi, (Tsi)Br(2)SiK, and (Tsi)Cl(2)SiLi were 106, 70, and 87 ppm, respectively.

  5. Extremely Na and Cl Rich Chondrule Al3509 from the Allende Meteorite

    NASA Astrophysics Data System (ADS)

    Wasserburg, G. J.; Hutcheon, I. D.; Aleon, J.; Ramon, E. C.; Krot, A. N.; Nagashima, K.; Brearley, A. J.

    2011-03-01

    This Ca-Al-rich chondrule is not a replacement product. It has ~10% Na and ~1% Cl. Large excesses of 36S were found uncorrelated with Cl and 26Al/27Al < 3 x 10^-6. It represents the fluid responsible for late alteration in volatile-rich outer layers prior to formation of Allende.

  6. Vicinal dihalonium ions: diprotonated and dimethylated chlorine [H2Cl2(2+), (CH3)2Cl2(2+)] and bromine [H2Br2(2+), (CH3)2Br2(2+)] dications.

    PubMed

    Olah, George A; Prakash, G K Surya; Rasul, Golam

    2010-04-13

    High level ab initio calculations at the MP2/cc-pVTZ, CCSD(T)/cc-pVTZ, and CASSCF(6,6)/cc-pVTZ levels were performed to investigate geometries and energies of superelectrophilic diprotonated, and dimethylated molecular chlorine (Cl2) and bromine (Br2) dications. Diprotonated chlorine and diprotonated bromine dications 3a and 6a, respectively, were found to be lowest energy minima. The isomeric dications, 3b and 6b, are also minima on the potential energy surfaces but they are significantly less stable than the structures 3a and 6a by 33.6 and 30.9 kcal/mol, respectively. On the basis of computed G2 energies, proton affinities and related thermodynamic parameters were also calculated. Dications 3a and 6a have substantial kinetic barriers for deprotonation. Their homolytic dissociation are however facile. Dimethylated molecular chlorine and bromine dications 3g and 6g, respectively, were also found to be global energy minima. These vicinal dihalonium or the corresponding protosolvated species are expected to form either in the superacidic media or in the gas phase.

  7. Further Analysis of Boiling Points of Small Molecules, CH[subscript w]F[subscript x]Cl[subscript y]Br[subscript z

    ERIC Educational Resources Information Center

    Beauchamp, Guy

    2005-01-01

    A study to present specific hypothesis that satisfactorily explain the boiling point of a number of molecules, CH[subscript w]F[subscript x]Cl[subscript y]Br[subscript z] having similar structure, and then analyze the model with the help of multiple linear regression (MLR), a data analysis tool. The MLR analysis was useful in selecting the…

  8. Heterogeneous photocatalysts BiOX/NaBiO3 (X = Cl, Br, I): Photo-generated charge carriers transfer property and enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Ji, Lei; Wang, Haoren; Yu, Ruimin

    2016-10-01

    BiOX/NaBiO3 (X = Cl, Br, I) heterostructures were synthesized by a simple chemical etching method using haloid acid as etching agents to react with NaBiO3. Several characterization tools including X-ray powder diffraction (XRD), scanning electron microscope (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS) were employed for structural and composition analyses of the samples. The as-prepared heterogeneous samples exhibited more efficient photocatalytic activities than pure NaBiO3 and BiOX (X = Cl, Br, I) for the degradation of Rhodamine B (RhB) under visible light (or UV light) irradiation, which could be attributed to the formation of the p-n junction between p-BiOX (X = Cl, Br, I) and n-NaBiO3, which effectively suppresses the recombination of photo-generated electron-hole pairs. Terephthalic acid photoluminescence (TA-PL) probing test and trapping agents experiments demonstrated that radOH (or h+) was the dominant reactive species depend on the different band gap structure of the p-n heterojunctions. Possible transfer processes of photo-generated charge carriers were proposed based on the band structures of BiOX/NaBiO3 (X = Cl, Br, I) and the experimental results.

  9. Antiferroelectric instability in the kagome francisites Cu3Bi (SeO3)2O2X (X =Cl ,Br )

    NASA Astrophysics Data System (ADS)

    Prishchenko, Danil A.; Tsirlin, Alexander A.; Tsurkan, Vladimir; Loidl, Alois; Jesche, Anton; Mazurenko, Vladimir G.

    2017-02-01

    Density-functional calculations of lattice dynamics and high-resolution synchrotron powder diffraction uncover antiferroelectric distortion in the kagome francisite Cu3Bi (SeO3)2O2Cl below 115 K. Its Br-containing analog is stable in the room-temperature crystal structure down to at least 10 K, although the Br compound is on the verge of a similar antiferroelectric instability and reveals local displacements of Cu and Br atoms. The I-containing compound is stable in its room-temperature structure according to density-functional calculations. We show that the distortion involves cooperative displacements of Cu and Cl atoms, and originates from the optimization of interatomic distances for weakly bonded halogen atoms. The distortion introduces a tangible deformation of the kagome spin lattice and may be responsible for the reduced net magnetization of the Cl compound compared to the Br one. The polar structure of Cu3Bi (SeO3)2O2Cl is only slightly higher in energy than the nonpolar antiferroelectric structure, but no convincing evidence of its formation could be obtained.

  10. Coupled evolution of BrOx-ClOx-HOx-NOx chemistry during bromine-catalyzed ozone depletion events in the arctic boundary layer

    NASA Astrophysics Data System (ADS)

    Evans, M. J.; Jacob, D. J.; Atlas, E.; Cantrell, C. A.; Eisele, F.; Flocke, F.; Fried, A.; Mauldin, R. L.; Ridley, B. A.; Wert, B.; Talbot, R.; Blake, D.; Heikes, B.; Snow, J.; Walega, J.; Weinheimer, A. J.; Dibb, J.

    2003-02-01

    Extensive chemical characterization of ozone (O3) depletion events in the Arctic boundary layer during the TOPSE aircraft mission in March-May 2000 enables analysis of the coupled chemical evolution of bromine (BrOx), chlorine (ClOx), hydrogen oxide (HOx) and nitrogen oxide (NOx) radicals during these events. We project the TOPSE observations onto an O3 chemical coordinate to construct a chronology of radical chemistry during O3 depletion events, and we compare this chronology to results from a photochemical model simulation. Comparison of observed trends in ethyne (oxidized by Br) and ethane (oxidized by Cl) indicates that ClOx chemistry is only active during the early stage of O3 depletion (O3 > 10 ppbv). We attribute this result to the suppression of BrCl regeneration as O3 decreases. Formaldehyde and peroxy radical concentrations decline by factors of 4 and 2 respectively during O3 depletion and we explain both trends on the basis of the reaction of CH2O with Br. Observed NOx concentrations decline abruptly in the early stages of O3 depletion and recover as O3 drops below 10 ppbv. We attribute the initial decline to BrNO3 hydrolysis in aerosol, and the subsequent recovery to suppression of BrNO3 formation as O3 drops. Under halogen-free conditions we find that HNO4 heterogeneous chemistry could provide a major NOx sink not included in standard models. Halogen radical chemistry in the model can produce under realistic conditions an oscillatory system with a period of 3 days, which we believe is the fastest oscillation ever reported for a chemical system in the atmosphere.

  11. Analytical investigation of AlCl[3]/SO[2]Cl[2] catholyte materials for secondary fuze reserve batteries.

    SciTech Connect

    Butler, Paul Charles; Rodriguez, Mark Andrew; Segall, Judith M.; Malizia, Louis A., Jr.; Cherry, Brian Ray; Andrews, Nicholas L.; Clark, Nancy H.; Alam, Todd Michael; Ingersoll, David T.; Tallant, David Robert; Simpson, Regina Lynn; Boyle, Timothy J.; Garcia, Manuel Joseph

    2004-05-01

    Exploration of the fundamental chemical behavior of the AlCl{sub 3}/SO{sub 2}Cl{sub 2} catholyte system for the ARDEC Self-Destruct Fuze Reserve Battery Project under accelerated aging conditions was completed using a variety of analytical tools. Four different molecular species were identified in this solution, three of which are major. The relative concentrations of the molecular species formed were found to depend on aging time, initial concentrations, and storage temperature, with each variable affecting the kinetics and thermodynamics of this complex reaction system. We also evaluated the effect of water on the system, and determined that it does not play a role in dictating the observed molecular species present in solution. The first Al-containing species formed was identified as the dimer [Al({mu}-Cl)Cl{sub 2}]{sub 2}, and was found to be in equilibrium with the monomer, AlCl{sub 3}. The second species formed in the reaction scheme was identified by single crystal X-ray diffraction studies as [Cl{sub 2}Al({mu}-O{sub 2}SCl)]{sub 2} (I), a scrambled AlCl{sub 3}{center_dot}SO{sub 2} adduct. The SO{sub 2}(g) present, as well as CL{sub 2}(g), was formed through decomposition of SO{sub 2}CL{sub 2}. The SO{sub 2}(g) generated was readily consumed by AlCl{sub 3} to form the adduct 1 which was experimentally verified when 1 was also isolated from the reaction of SO{sub 2}(g) and AlCl {sub 3}. The third species found was tentatively identified as a compound having the general formula {l_brace}[Al(O)Cl{sub 2}][OSCl{sub 2}]{r_brace}{sub n}. This was based on {sup 27}Al NMR data that revealed a species with tetrahedrally coordinated Al metal centers with increased oxygen coordination and the fact that the precipitate, or gel, that forms over time was shown by Raman spectroscopic studies to possess a component that is consistent with SOCl{sub 2}. The precursor to the precipitate should have similar constituents, thus the assignment of {l_brace}[Al(O)Cl{sub 2}][OSCl{sub 2

  12. Ion Association in AlCl3 Aqueous Solutions from Constrained First-Principles Molecular Dynamics

    SciTech Connect

    Cauet, Emilie L.; Bogatko, Stuart A.; Bylaska, Eric J.; Weare, John H.

    2012-10-15

    Ab initio molecular dynamics was used to investigate the ion pairing behavior between Cl- and the Al3+ ion in an aqueous AlCl3 solution containing 63 water molecules. A series of constrained simulations was carried out at 300 K for up to 16 ps each, by fixing the inter-nuclear separation (rAl-Cl) between the Al3+ ion and one of the Cl- ions. The calculated potential of mean force of the Al3+-Cl- ion pair shows a pronounced minimum at rAl-Cl = 2.3 Å corresponding to a contact ion pair (CIP). Two local minima assigned to solvent separated ion pairs (SSIP) are identified at rAl-Cl= 4.4 and 6.0 Å. The positions of the free energy minima coincide with the hydration shell intervals of the Al3+ cation suggesting that the Cl- ion is inclined to reside in regions of low concentration of waters, i.e. between the 1st and 2nd shells of Al3+ and between the 2nd shell and bulk. A detailed analysis of solvent structure around the Al3+ and Cl- ions as a function of rAl-Cl is presented. The results are compared to structure data from X-ray measurements and unconstrained AIMD simulations of single ions Al3+ and Cl- and AlCl3 solutions. The dipole moment of the water molecules inside the 1st and 2nd hydration shells of Al3+ and in the bulk region and those of the Clion were calculated as a function of rAl-Cl. Major changes in the electronic structure of the system result from the removal of Cl- from the 1st hydration shell of the Al3+ cation. Finally, two unconstrained AIMD simulations of aqueous AlCl3 solutions corresponding to CIP and SSIP configurations were performed (17 ps, 300 K). Only minor structural changes are observed in these systems, confirming their stability.

  13. Synthesis and structure of fullerene halides in the C{sub 60}-(TiCl{sub 4} + Br{sub 2}) system: Molecular structures of (C{sub 60}Cl{sub 5}){sub 2}, C{sub 60}X{sub 6}, C{sub 60}X{sub 8}, and C{sub 60}X{sub 24}(X = Cl, Br)

    SciTech Connect

    Troyanov, S. I. Burtsev, A. V.; Kemnitz, E.

    2009-03-15

    The reactions in the C{sub 60}-(TiCl{sub 4} + Br{sub 2}) system have been performed in ampoules at elevated temperatures. The molecular structure of the fullerene halides (C{sub 60}Cl{sub 5}){sub 2}, C{sub 60}X{sub 6}, C{sub 60}X{sub 8}, and C{sub 60}X{sub 24} (X = Cl, Br) has been determined and refined using single-crystal X-ray diffraction. It has been established that an increase in the bromine concentration results in an increase in the number of halogen atoms attached to the fullerene cage and in an increase in the relative fraction of bromine atoms in mixed halogen derivatives from almost pure chlorides (C{sub 60}Cl{sub 5}){sub 2} and C{sub 60}Cl{sub 6} to halides C{sub 60}X{sub 8} and C{sub 60}X{sub 24} with a high relative bromine content.

  14. The nature of inter- and intramolecular interactions in F2OXe(…)HX (X= F, Cl, Br, I) complexes.

    PubMed

    Makarewicz, Emilia; Lundell, Jan; Gordon, Agnieszka J; Berski, Slawomir

    2016-06-01

    Electronic structure of the XeOF2 molecule and its two complexes with HX (X= F, Cl, Br, I) molecules have been studied in the gas phase using quantum chemical topology methods: topological analysis of electron localization function (ELF), electron density, ρ(r), reduced gradient of electron density |RDG(r)| in real space, and symmetry adapted perturbation theory (SAPT) in the Hilbert space. The wave function has been approximated by the MP2 and DFT methods, using APF-D, B3LYP, M062X, and B2PLYP functionals, with the dispersion correction as proposed by Grimme (GD3). For the Xe-F and Xe=O bonds in the isolated XeOF2 molecule, the bonding ELF-localization basins have not been observed. According to the ELF results, these interactions are not of covalent nature with shared electron density. There are two stable F2OXe(…)HF complexes. The first one is stabilized by the F-H(…)F and Xe(…)F interactions (type I) and the second by the F-H(…)O hydrogen bond (type II). The SAPT analysis confirms the electrostatic term, Eelst ((1)) and the induction energy, Eind ((2)) to be the major contributors to stabilizing both types of complexes.

  15. Corrosion of Sn-Co alloy in alkaline media and the effect of Cl - and Br - ions

    NASA Astrophysics Data System (ADS)

    Refaey, S. A. M.

    1999-05-01

    Sn-Co electrodeposits alloy of approximate composition 80% Sn-20% Co (wt%) can be obtained from a gluconate bath as single phase CoSn 2, which is similar in appearance to decorative chromium. The potentiodynamic and cyclic voltammogram techniques were used to study the corrosion behaviour of CoSn 2 in sodium borate solutions (Na 2B 4O 7) at pH=9.6. The effect of different factors such as concentration of borate ions, pH, potential scan rate, successive cyclic voltammetry, and progressive addition of halide ions (Cl - and Br -) on the electrochemical behaviour of CoSn 2 alloys are discussed. The observed corrosion resistance of electrodeposited CoSn 2 alloy is due to the formation of a thin passive film, which is examined by X-ray spectroscopy and believed to be mainly tin and cobalt oxides. The voltammograms involve four anodic peaks, the first and second of which correspond to the formation of SnO and SnO 2 and the third and fourth related to the formation of cobalt oxides. SEM examination confirms that pitting corrosion takes place in presence of borax and is increased by adding halide ions.

  16. Parameterization of the DFTB3 method for Br, Ca, Cl, F, I, K, and Na in organic and biological systems.

    PubMed

    Kubillus, Maximilian; Kubař, Tomáš; Gaus, Michael; Řezáč, Jan; Elstner, Marcus

    2015-01-13

    We present an extension to the recent 3OB parametrization of the Density Functional Tight Binding Model DFTB31,2 for biological and organic systems. Parameters for the halogens F, Cl, Br, and I have been developed for use in covalently bound systems and benchmarked on a test set of 106 molecules (the ‘OrgX’ set), using bonding distances, bonding angles, atomization energies, and vibrational frequencies to assess the performance of the parameters. Additional testing has been done with the X40 set of 40 supramolecular systems containing halogens,3 adding a simple correction for the halogen bonds that are strongly overbound in DFTB3. Furthermore, parameters for Ca, K, and Na as counterions in biological systems have been created. To benchmark geometries as well as ligand binding energies a test set ‘BioMe’ of 210 molecules has been created that cover coordination to various functional groups frequently occurring in biological systems. The new DFTB3/3OB parameter set outperforms DFT calculations with a double-ζ basis set in terms of energies and can reproduce DFT geometries, with some minor deviations in bond distances and angles due to the use of a minimal basis set.

  17. Reaction mechanism studies towards effective fabrication of lithium-rich anti-perovskites Li3OX (X=Cl, Br)

    DOE PAGES

    Li, Shuai; Zhu, Jinlong; Wang, Yonggang; ...

    2015-12-10

    Lithium-rich Anti-perovskite (LiRAP), with general formula Li3OX (X = Cl, Br, I), and recently reported as superionic conductors with 3-dimensional Li+ migrating channels, is emerging as a promising candidate for solid electrolyte of all-solid-state LIBs. But, it is still difficult to fabricate pure LiRAP due to the difficulty of the phase formation and moisture-sensitive nature of the products. In this work, we thoroughly studied the formation mechanism of Li3OCl and Li3OBr in various solid state reaction routes. We developed different experimental strategies in order to improve the syntheses, in purposes of improved phase stability and large-scale production of LiRAP. Onemore » feasible method is to use strongly reductive agents Li metal or LiH to eliminate OH species. The results show that LiH is more effective than Li metal because of negatively charged H- and uniform reaction. The other well-established method is using Li2O and LiX mixture as reagents to preventing OH phase at the beginning, and using protected ball milling to make fine powders and hence active the reaction. Finally, IR spectroscopy, thermal analyses and first-principle calculation were performed to give indications on the reaction pathway.« less

  18. Molecular Dynamics Analysis of Ion Incident Energy and Angle Dependences of Si etching with Cl, Br, and HBr beams

    NASA Astrophysics Data System (ADS)

    Nakazaki, Nobuya; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2011-10-01

    Profile anomalies and surface roughness are now critical issues to be resolved in the plasma etching of nanometer-scale microelectronic devices, which in turn requires a better understanding of the effects of the ion incident angle on surface reaction kinetics. For example, the line edge and line width roughness of feature sidewalls and the roughness of bottom surfaces of the feature are assumed to be caused by the angular distribution of incident ions onto feature surfaces. This paper presents a classical molecular dynamics (MD) simulation of Si(100) etching by Cl+, Br+, and HBr+ ion beams with different incident energies (Ei = 20-300 eV) and angles (θ = 0°-90°), where an improved Stillinger-Weber interatomic potential model is used for Si/halogen interactions. The results indicated that the surface reaction kinetics exhibit a characteristic of the ion-enhanced etching at lower energies, where the etch yield is maximum at normal incidence, while a characteristics of the physical sputtering at higher energies, where the yield is maximum at off-normal incidence.

  19. Synthesis and single-crystal structure determination of the zinc nitride halides Zn2NX (X=Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Liu, Xiaohui; Wessel, Claudia; Pan, Fangfang; Dronskowski, Richard

    2013-07-01

    A series of zinc nitride halides, Zn2NX (X=Cl, Br, I), has been synthesized from solid-liquid reactions of zinc nitride with the respective zinc halides under vacuum, and their crystal structures were determined using single-crystal and powder X-ray diffraction. While Zn2NCl and Zn2NBr crystallize in the acentric orthorhombic space group Pna21, Zn2NI adopts the centrosymmetric space group Pnma; Zn2NCl and Zn2NBr can be considered to belong to the anti-β-NaFeO2 type, and Zn2NI is closely related. Each N3- is tetrahedrally coordinated by zinc atoms, and the X- anions are located in the vacancies of the framework formed by corner-sharing [NZn4] tetrahedra. According to TGA/DTA analyses, the Zn2NX compounds exhibit good thermal stability. The electronic structure has been analyzed by employing density-functional theory and the HSE06 hybrid functional.

  20. Structural phase transitions of ionic layered PbFX (X = Cl{sup −}or Br{sup –}) compounds under high pressure

    SciTech Connect

    Sorb, Y.A. Sornadurai, D.

    2015-05-15

    The PbFX (X = Cl{sup –}or Br{sup –}) compounds crystallize in tetragonal structure with space group P4/nmm. High pressure X-ray diffraction studies carried out on PbFCl compound reveals that it undergoes pressure induced structural transitions at ∼18 GPa and ∼38 GPa to orthorhombic and monoclinic (P2{sub 1}/m) phases respectively. Like PbFCl, a similar phase transition from tetragonal to orthorhombic phase is observed in PbFBr at intermediate pressure. These phase transitions seem to be similar to the transitions involving other matlockite structure compounds such as BaFX (X = Cl{sup –}, Br{sup –}or I{sup –}). PbFCl has a larger structural stability range compared to BaFCl and is attributed to the large anisotropic coordination of the Pb{sup 2+} and Cl{sup –}ions.

  1. Quality Structures, Vibrational Frequencies, and Thermochemistry of the Products of Reaction of BrHg(•) with NO2, HO2, ClO, BrO, and IO.

    PubMed

    Jiao, Yuge; Dibble, Theodore S

    2015-10-22

    Quantum chemical calculations have been carried out to investigate the structures, vibrational frequencies, and thermochemistry of the products of BrHg(•) reactions with atmospherically abundant radicals Y(•) (Y = NO2, HO2, ClO, BrO, or IO). The coupled cluster method with single and double excitations (CCSD), combined with relativistic effective core potentials, is used to determine the equilibrium geometries and harmonic vibrational frequencies of BrHgY species. The BrHg-Y bond energies are refined using CCSD with a noniterative estimate of the triple excitations (CCSD(T)) combined with core-valence correlation consistent basis sets. We also assess the performances of various DFT methods for calculating molecular structures and vibrational frequencies of BrHgY species. We attempted to estimate spin-orbit coupling effects on bond energies computed by comparing results from standard and two-component spin-orbit density functional theory (DFT) but obtained unphysical results. The results of the present work will provide guidance for future studies of the halogen-initiated chemistry of mercury.

  2. Density functional study of S(N) 2 substitution reactions for CH(3) Cl + CX(1) X(2•-) (X(1) X(2) = HH, HF, HCl, HBr, HI, FF, ClCl, BrBr, and II).

    PubMed

    Liang, Jun-Xi; Geng, Zhi-Yuan; Wang, Yong-Cheng

    2012-03-05

    A systematic investigation on the S(N) 2 displacement reactions of nine carbene radical anions toward the substrate CH(3) Cl has been theoretically carried out using the popular density functional theory functional BHandHLYP level with different basis sets 6-31+G (d, p)/relativistic effective core potential (RECP), 6-311++G (d, p)/RECP, and aug-cc-pVTZ/RECP. The studied models are CX(1) X(2•-) + CH(3) Cl → X(2) X(1) CH(3) C(•) + Cl(-) , with CX(1) X(2•-) = CH(2) (•-) , CHF(•-) , CHCl(•-) , CHBr(•-) , CHI(•-) , CF(2) (•-) , CCl(2) (•-) , CBr(2) (•-) , and CI(2) (•-) . The main results are proposed as follows: (a) Based on natural bond orbital (NBO), proton affinity (PA), and ionization energy (IE) analysis, reactant CH(2) (•-) should be a strongest base among the anion-containing species (CX(1) X(2•-) ) and so more favorable nucleophile. (b) Regardless of frontside attacking pathway or backside one, the S(N) 2 reaction starts at an identical precomplex whose formation with no barrier. (c) The back-S(N) 2 pathway is much more preferred than the front-S(N) 2 one in terms of the energy gaps [ΔE cent≠(front)-ΔE cent≠(back)], steric demand, NBO population analysis. Thus, the back-S(N) 2 reaction was discussed in detail. On the one hand, based on the energy barriers (ΔE cent≠ and ΔE ovr≠) analysis, we have strongly affirmed that the stabilization of back attacking transition states (b-TSs) presents increase in the order: b-TS-CI(2) < b-TS-CBr(2) < b-TS-CCl(2) < b-TS-CHI < b-TS-CHBr < b-TS-CHCl < b-TS-CF(2) < b-TS-CHF < b-TS-CH(2) . On the other hand, depended on discussions of the correlations of ΔE ovr≠ with influence factors (PA, IE, bond order, and ΔE def≠), we have explored how and to what extent they affect the reactions. Moreover, we have predicted that the less size of substitution (α-atom) required for the gas-phase reaction with α-nucleophile is related to the α-effect and estimated that the reaction

  3. Recent developments in the magnetic study of the deformed pyrochlore lattice M2(OH)3X (M = 3d magnetic ions, X = Cl, Br) - exotic magnetic order in Ni2(OH)3Cl and controlled spin-spin interactions in Co2(OH)3Cl1-xBrx and (Co1-xFex)2(OH)3Cl

    NASA Astrophysics Data System (ADS)

    Zheng, X. G.; Hagihala, M.; Fujihala, M.; Kawae, T.

    2009-01-01

    Following the discovery of frustrated magnetism in deformed pyrochlore lattice Cu2(OH)3Cl and Co2(OH)3Cl we have extensively investigated the material series in the chemical formula of M2(OH)3X, with M = Cu, Co, Ni, Fe, Mn, and X = Cl, Br, or I. In atacamite-structure Ni2(OH)3Cl, strong geometric frustration and an exotic antiferromagnetic transition below 5 K was found. While neutron diffraction witnessed unambiguously an antiferromagnetic long-range order, the μSR method can't 'see' this order, instead, the detected local field behaved quite like a dynamically fluctuating one. For the system of Co2(OH)3Cl, the magnetic state is very sensitive to both the anion and cation substitution. While Co2(OH)3Cl behaves like a zero-field kagomé ice ferromagnet, a completely substituted version of Co2(OH)3Br becomes antiferromagnetic although there is little difference in the crystal structure. The antiferromagnetic Co2(OH)3Br showed complicated magnetic transitions. Meanwhile, partially substituted Co2(OH)3Cl1-xBrx transforms from ferromagnetic to antiferromagnetic with increasing the x ratio. The results suggest that the interaction on the kagome-lattice plane is antiferromagnetic while that on the triangular lattice plane is ferromagnetic. For the substituted series (Co1-xFex)2(OH)3Cl a spin glass state is observed.

  4. Strongly visible-light responsive plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles for reduction of CO2 to methanol

    NASA Astrophysics Data System (ADS)

    An, Changhua; Wang, Jizhuang; Jiang, Wen; Zhang, Meiyu; Ming, Xijuan; Wang, Shutao; Zhang, Qinhui

    2012-08-01

    Plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles have been synthesized by a facile and versatile glycerol-mediated solution route. The as-prepared AgX:Ag nanoparticles exhibit regular shapes, i.e., cube-tetrapod-like AgCl:Ag nanoparticles and AgBr:Ag nanoplates. Compared with the pristine AgX, AgX:Ag nanocomposites display stronger absorption in the visible region due to the surface plasmon resonance of silver nanoparticles. The calculation of bandgaps and band positions indicates the as-achieved AgX:Ag nanoparticles can be used as a class of potential photocatalyst for the reduction of CO2. For example, reduction of CO2 under visible light irradiation with the assistance of the anisotropic AgX:Ag nanoparticles yields as much as 100 μmol methanol in the products. Furthermore, the AgX:Ag nanoparticles can maintain its structure and activity after 3 runs of reactions. Therefore, the present route opens an avenue to acquire plasmonic photocatalysts for conversion of CO2 into useful organic compounds.Plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles have been synthesized by a facile and versatile glycerol-mediated solution route. The as-prepared AgX:Ag nanoparticles exhibit regular shapes, i.e., cube-tetrapod-like AgCl:Ag nanoparticles and AgBr:Ag nanoplates. Compared with the pristine AgX, AgX:Ag nanocomposites display stronger absorption in the visible region due to the surface plasmon resonance of silver nanoparticles. The calculation of bandgaps and band positions indicates the as-achieved AgX:Ag nanoparticles can be used as a class of potential photocatalyst for the reduction of CO2. For example, reduction of CO2 under visible light irradiation with the assistance of the anisotropic AgX:Ag nanoparticles yields as much as 100 μmol methanol in the products. Furthermore, the AgX:Ag nanoparticles can maintain its structure and activity after 3 runs of reactions. Therefore, the present route opens an avenue to acquire plasmonic photocatalysts for conversion of CO2

  5. Uniaxial Orientational Order-Disorder Transitions in Diammine Magnesium Halides, Mg(ND 3) 2Cl 2 and Mg (ND 3) 2Br 2, Investigated by Neutron Diffraction

    NASA Astrophysics Data System (ADS)

    Leineweber, A.; Jacobs, H.; Fischer, P.; Böttger, G.

    2001-02-01

    Neutron powder diffraction on Mg(ND3)2Cl2 and Mg(ND3)2Br2 revealed as a function of temperature uniaxial orientational order-disorder behavior of the ND3 groups. The crystal structures of both compounds are built up from chains of octahedra 1∞[Mg(NH3)2X4/2] with X=Cl and Br arranged in different ways relative to each other. At ambient temperatures (X=Cl) and 270 K (X=Br) the ND3 groups are disordered with respect to a rotation about the bond Mg-N. The D atom density is well described by a fourfold split position, each D "site" connecting an N with an X atom: Mg(ND3)2Cl2, Cmmm, a=8.1828(6) Å, b=8.2007(6) Å, c=3.7543(2) Å, R(F2)Bragg=5.9%; Mg(ND3)2Br2, Pbam, a=5.9714(2) Å, b=11.9175(3) Å, c=3.98477(8) Å, R(F2)Bragg=7.9%. In both cases the c axis corresponds to the direction of the chains 1∞[Mg(NH3)2X4/2]. At low temperatures (8 K (X=Cl) and 1.5 K (X=Br)) both compounds are ordered with respect to the ND3 groups: They are arranged antiferroelectrically on either side of the chains 1∞[Mg(NH3)2X4/2]. The symmetry is lowered compared to the situation at ambient temperatures and 270 K respectively, which involves in both cases a doubling of the orthorhombic c axis: Mg(ND3)2Cl2, Ibmm, a=8.1319(3) Å, b=8.1338(3) Å, c=7.4410(2) Å, R(F2)Bragg=5.9%; Mg(ND3)2Br2, Pnam, a= 5.92837(8) Å, b=11.8448(2) Å, c=7.9117(1) Å, R(F2)Bragg=5.0%. Detailed evaluation of neutron diffraction data of Mg(ND3)2Cl2 as a function of temperature (50 K

  6. Fast Anion-Exchange in Highly Luminescent Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I)

    PubMed Central

    2015-01-01

    Postsynthetic chemical transformations of colloidal nanocrystals, such as ion-exchange reactions, provide an avenue to compositional fine-tuning or to otherwise inaccessible materials and morphologies. While cation-exchange is facile and commonplace, anion-exchange reactions have not received substantial deployment. Here we report fast, low-temperature, deliberately partial, or complete anion-exchange in highly luminescent semiconductor nanocrystals of cesium lead halide perovskites (CsPbX3, X = Cl, Br, I). By adjusting the halide ratios in the colloidal nanocrystal solution, the bright photoluminescence can be tuned over the entire visible spectral region (410–700 nm) while maintaining high quantum yields of 20–80% and narrow emission line widths of 10–40 nm (from blue to red). Furthermore, fast internanocrystal anion-exchange is demonstrated, leading to uniform CsPb(Cl/Br)3 or CsPb(Br/I)3 compositions simply by mixing CsPbCl3, CsPbBr3, and CsPbI3 nanocrystals in appropriate ratios. PMID:26207728

  7. Fast Anion-Exchange in Highly Luminescent Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I).

    PubMed

    Nedelcu, Georgian; Protesescu, Loredana; Yakunin, Sergii; Bodnarchuk, Maryna I; Grotevent, Matthias J; Kovalenko, Maksym V

    2015-08-12

    Postsynthetic chemical transformations of colloidal nanocrystals, such as ion-exchange reactions, provide an avenue to compositional fine-tuning or to otherwise inaccessible materials and morphologies. While cation-exchange is facile and commonplace, anion-exchange reactions have not received substantial deployment. Here we report fast, low-temperature, deliberately partial, or complete anion-exchange in highly luminescent semiconductor nanocrystals of cesium lead halide perovskites (CsPbX3, X = Cl, Br, I). By adjusting the halide ratios in the colloidal nanocrystal solution, the bright photoluminescence can be tuned over the entire visible spectral region (410-700 nm) while maintaining high quantum yields of 20-80% and narrow emission line widths of 10-40 nm (from blue to red). Furthermore, fast internanocrystal anion-exchange is demonstrated, leading to uniform CsPb(Cl/Br)3 or CsPb(Br/I)3 compositions simply by mixing CsPbCl3, CsPbBr3, and CsPbI3 nanocrystals in appropriate ratios.

  8. First Principle Quantum Description of the Energetics Associated with LaBr3, LaCl3, and Ce Doped Scintillators

    SciTech Connect

    Michael E. McIlwain; Da Gao; Nick Thompson

    2007-12-01

    Considerable interest is given to the excellent scintillation properties of cerium doped lanthanum chloride (LaCl3) and lanthanum bromide (LaBr3). The scintillation efficiencies are much greater than other materials, even those containing cerium. This high efficiency is attributed to the high mobility of electrons and holes, unique placement of the cerium 5d states within the band gap, and energy of the band gap. To better understand the scintillation process and better define the nature of the Self Trapped Exciton (STE) within these unique scintillation materials, density functional theory (DFT), and Ab-inito (HF-MP2) calculations are reported. DFT calculations have yielded a qualitative description of the orbital composition and energy distribution of the band structure in the crystalline material. MP2 and single configuration interaction calculations have provided quantitative values for the band gap and provided energies for the possible range of excited states created following hole and electron creation. Based on this theoretical treatment, one possible description of the STE is the combination of Vk center (Br2-1) and LaBr+1 species that recombine to form a distorted geometry LaBr3* (triplet state). Depending on the distance between the LaBr and Br2, the STE emission band can be reproduced.

  9. Vapor-Phase Epitaxial Growth of Aligned Nanowire Networks of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I).

    PubMed

    Chen, Jie; Fu, Yongping; Samad, Leith; Dang, Lianna; Zhao, Yuzhou; Shen, Shaohua; Guo, Liejin; Jin, Song

    2017-01-11

    With the intense interest in inorganic cesium lead halide perovskites and their nanostructures for optoelectronic applications, high-quality crystalline nanomaterials with controllable morphologies and growth directions are desirable. Here, we report a vapor-phase epitaxial growth of horizontal single-crystal CsPbX3 (X = Cl, Br, I) nanowires (NWs) and microwires (MWs) with controlled crystallographic orientations on the (001) plane of phlogopite and muscovite mica. Moreover, single NWs, Y-shaped branches, interconnected NW or MW networks with 6-fold symmetry, and, eventually, highly dense epitaxial network of CsPbBr3 with nearly continuous coverage were controllably obtained by varying the growth time. Detailed structural study revealed that the CsPbBr3 wires grow along the [001] directions and have the (100) facets exposed. The incommensurate heteroepitaxial lattice match between the CsPbBr3 and mica crystal structures and the growth mechanism of these horizontal wires due to asymmetric lattice mismatch were proposed. Furthermore, the photoluminescence waveguiding and good performance from the photodetector device fabricated with these CsPbBr3 networks demonstrated that these well-connected CsPbBr3 NWs could serve as straightforward platforms for fundamental studies and optoelectronic applications.

  10. Influence of Halogen Variation on Structure and Interactions in Vinyl Halide (H_2C=CHX)\\cdotsCO_2 (x = F, Cl, Br) Complexes

    NASA Astrophysics Data System (ADS)

    Anderton, Ashley M.; Christenholz, Cori L.; Dorris, Rachel E.; Peebles, Rebecca A.; Peebles, Sean A.

    2016-06-01

    Chirped-pulse and resonant cavity Fourier-transform microwave spectroscopy have been used to investigate dimers of CO_2 with vinyl fluoride (VF), vinyl chloride (VCl) and vinyl bromide (VBr). For all three complexes, CO_2 is aligned adjacent to the X-C-H end (X = F, Cl, Br) of the ethylene subunit, with C-X\\cdotsC and C-H\\cdotsO contacts. For VF\\cdotsCO_2, a second isomer is also observed, with CO_2 roughly parallel to the H-C=C-F side of VF; however, there is no spectroscopic indication that similar structures are present for VCl\\cdotsCO_2 or VBr\\cdotsCO_2. For vinyl fluoride\\cdotsCO_2, a full structural analysis has previously been published, while for the Cl- and Br-containing species, insufficient data are presently available for complete structure determinations. However, structural information from ab initio calculations, 35Cl/37Cl and 79B/81Br isotopic substitution, and analysis of chlorine and bromine nuclear quadrupole coupling constants will be presented. In addition, for this series of dimers containing C-H\\cdotsO contacts, further insight into the nature of the weak interactions may be obtained from Quantum Theory of Atoms in Molecules (QTAIM) and other ab initio} analyses that are presently in progress. C. L. Christenholz, R. E. Dorris, R. A. Peebles, S. A. Peebles, J. Phys. Chem. A, 118, (2014), 8765-8772.

  11. Direct observation of reductive elimination of MeX (X = Cl, Br, I) from Rh(III) complexes: mechanistic insight and the importance of sterics.

    PubMed

    Feller, Moran; Diskin-Posner, Yael; Leitus, Gregory; Shimon, Linda J W; Milstein, David

    2013-07-31

    Rare cases of directly observed reductive elimination (RE) of methyl halides from Rh(III) complexes are described. Treatment of the coordinatively unsaturated complexes [((t)BuPNP)Rh(CH3)X][BF4] (1-3, X = I, Br, and Cl; (t)BuPNP = 2,6-bis-(di-tert-butylphosphinomethyl)pyridine) with coordinating and noncoordinating compounds results in the formation of the corresponding free methyl halides and Rh(I) complexes. The rate increase of CH3I and CH3Br RE in the presence of polar aprotic solvents argues in favor of an SN2 RE mechanism. However, the RE of CH3Cl is faster in polar protic solvents, which argues in favor of a concerted C-Cl RE. The RE of methyl halides from complexes 1-3 is induced by steric factors, as treatment of the less bulky complexes [((i)PrPNP)Rh(CH3)X][BF4] (19-21; X = I, Br, Cl, respectively) with coordinating compounds leads to the formation of the adducts complexes rather than RE of the methyl halides. The accumulated evidence suggests that the RE process is nonassociative.

  12. Kinetics of the Reactions of Cl((sup 2)P(sub J)) and Br((sup 2)P(sub 3/2)) with O3

    NASA Technical Reports Server (NTRS)

    Nicovich, J. M.; Kreutter, K. D.; Wine, P. H.

    1997-01-01

    A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of the important stratospheric reactions Cl((sup 2)P(sub J)) + O3 yields ClO + O2 and Br((sup 2)P(sub 3/2)) + O3 yields BrO + O2 as a function of temperature. The temperature dependence observed for the Cl((sup 2)P(sub J)) + O3 reaction is nonArrhenius, but can be adequately described by the following two Arrhenius expressions (units are cu cm/(molecule.s), errors are 2 sigma and represent precision only): k(sub 1)(T) = (1.19 +/- 0.21) x 10(exp -11) exp[(-33 +/- 37)/T] for T = 189-269 K and k(sub 1)(T) = (2.49 +/- 0.38) x 10(exp -11) exp[(-233 +/- 46)/T] for 269-385 K. At temperatures below 230 K, the rate coefficients determined in this study are faster than any reported previously. Incorporation of our values for k(sub 1)(T) into stratospheric models would increase calculated ClO levels and decrease calculated HCI levels; hence the calculated efficiency of ClO catalyzed ozone destruction would increase. The temperature dependence observed for the Br((sup 2)P(sub 3/2)) + O3 reaction is adequately described by the following Arrhenius expression (units are cu cm/(molecule.s), errors are 2 sigma and represent precision only): k(sub 2)(T) = (1.50 +/- 0.16) x 10(exp -11)exp[(-775 +/- 30)/T for 195-392 K. While not in quantitative agreement with Arrhenius parameters reported in most previous studies, our results almost exactly reproduce the average of all earlier studies and therefore will not affect the choice of k(sub 2)(T) for use in modeling stratospheric BrO2 chemistry.

  13. The role of reduction extent of graphene oxide in the photocatalytic performance of Ag/AgX (X = Cl, Br)/rGO composites and the pseudo-second-order kinetics reaction nature of the Ag/AgBr system.

    PubMed

    Gao, Weiyin; Ran, Chenxin; Wang, Minqiang; Li, Le; Sun, Zhongwang; Yao, Xi

    2016-07-21

    Although reduced graphene oxide (rGO)-based photocatalyst composites have been intensively developed during the past few years, the influence of reduction extent of rGO on the photocatalytic performance of the rGO-based composite has virtually not been investigated due to some technical limitations, such as the poor water dispersibility of rGO and low reduction selectivity of the hydrothermal method, which make it difficult to control the reduction extent of rGO in these composites. Herein, we used a facile room-temperature method to synthesize Ag/AgX (X = Cl, Br)/rGO photocatalyst composites as a model to study the effect of reduction extent of rGO on the photocatalytic performance of the photocatalyst. It was found that the photocatalytic activities of both Ag/AgCl/PrGO and Ag/AgBr/PrGO systems had an optimized threshold of the reduction extent of photoreduced GO (PrGO). More importantly, due to the different conductive band values of AgCl and AgBr, the optimized thresholds in the two systems were at different PrGO reduction extents, based on which we proposed that the favorable energy band matching between AgX and PrGO in the two systems played a crucial role in obtaining high photocatalysis performance. Besides, the photocatalytic reaction of the Ag/AgBr based system was confirmed to be a pseudo-second-order kinetics reaction rather than pseudo-first-order kinetics reaction. The new insights presented in this work provided useful information on the design and development of a more sophisticated photocatalyst, and can also be applied to many other applications.

  14. Plasmon-exciton couplings in Al-CuCl nanoshells and the effects of oxidation

    NASA Astrophysics Data System (ADS)

    Yao, Jie; Ji, WenQian; Wu, DaJian; Cheng, Ying; Liu, XiaoJun

    2017-04-01

    The plasmon-exciton couplings in the Al-CuCl nanoshells have been investigated by using the Mie scattering theory. It is found that the bright dipole mode of the Al nanosphere can couple well with the exciton mode of the outer CuCl shell in the UV region by changing the geometry. The strong plasmon-exciton couplings in the Al-CuCl nanoshell lead to two hybrid plexcitonic modes and hence the Rabi splitting. We study the dispersion curves of the plexcitonic modes of the Al-CuCl nanoshells and obtain the splitting energy of about 135 meV. Furthermore, the influences of the metal oxide on the plasmon-exciton couplings in the Al-CuCl nanoshells have been studied. It is found that the Rabi splitting energy will shrink with the oxide.

  15. Beryllium-Free KBBF Family of Nonlinear-Optical Crystals: AZn2BO3X2 (A = Na, K, Rb; X = Cl, Br).

    PubMed

    Huang, Qian; Liu, Lijuan; Wang, Xiaoyang; Li, Rukang; Chen, Chuangtian

    2016-12-19

    A series of a novel beryllium-free KBBF family of nonlinear-optical materials AZn2BO3X2 (A = K, Rb and X = Cl; A = Na, K, Rb and X = Br) were successfully synthesized through molecular engineering design, and single crystals of AZn2BO3Cl2 (A = K, Rb) were grown by a spontaneous nucleation technique from self-flux systems. As a representative for the halogen KBBF family of crystals, KZn2BO3Cl2 features the infinite lattice layer [Zn2BO3Cl2]∞ made up of BO3 and ZnO3Cl anionic groups, and the in-layer BO3 groups are completely coplanar and well-aligned. Besides, KZn2BO3Cl2 exhibits high transmittance in the range of 300-2000 nm with a UV-transmission cutoff of around 200 nm according to transmission spectra. The compounds of AZn2BO3Cl2 (A = K, Rb) are both phase-matchable with powder second-harmonic-generation efficiencies of 1.3 and 1.17 times that of KH2PO4 for KZn2BO3Cl2 and RbZn2BO3Cl2, respectively, which are similar to that of KBBF.

  16. Behavior of BrO3F and ClO3F toward strong Lewis acids and the characterization of [XO2][SbF6] (X = Cl, Br) by single crystal X-ray diffraction, Raman spectroscopy, and computational methods.

    PubMed

    Lehmann, John F; Riedel, Sebastian; Schrobilgen, Gary J

    2008-09-15

    The interactions of BrO3F and ClO3F with the strong Lewis acids AsF5 and SbF5 were investigated. Although ClO3F is unreactive toward AsF5 and SbF5, BrO3F undergoes fluoride ion abstraction and O2 elimination, accompanied by central halogen reduction, to form [BrO2][Sb(n)F(5n+1)] (n > or = 1), rather than simple fluoride ion abstraction to form BrO3(+) salts. The geometric parameters of the BrO2(+) cation have been obtained in the solid state for the first time by a single-crystal X-ray diffraction study of [BrO2][SbF6] at -173 degrees C and are compared with those of ClO2(+) salts. Quantum-chemical calculations have been used to arrive at the geometries and vibrational frequencies of XO2(+) and XO3(+) (X = Cl, Br) and have been compared with the experimental values for XO2(+). The calculations have also been used to account for the contrasting behaviors of ClO3F and BrO3F toward central halogen reduction in the presence of liquid SbF5. The thermochemical stabilities of ClO3(+) and BrO3(+) salts of the AsF6(-), SbF6(-), Sb2F11(-), and Sb3F16(-) were also investigated, which provided the fluoride ion affinities of AsF5, SbF5, Sb2F10, and Sb3F15 up to and including the CCSD(T) level of theory. These values are compared with the current literature values. Thermochemical studies indicate that XO3(+) formation by fluoride ion abstraction from XO3F is not spontaneous under standard conditions whereas a concerted fluoride abstraction and O2 elimination to give the XO2(+) cations is spontaneous to near thermally neutral. Failure to observe reactivity between ClO3F and any of the aforementioned Lewis acid fluoride ion acceptors is attributed to a significant kinetic barrier to fluoride ion abstraction.

  17. Heterogeneous reaction HOCl + HBr {r_arrow} BrCl + H{sub 2}O on ice films

    SciTech Connect

    Chu, L.; Chu, L.T.

    1999-02-11

    Heterogeneous reactions on the surface of polar stratospheric clouds (PSCs) are critical to an understanding of the annual appearance of the Antarctic ozone hole. The heterogeneous reaction HOCl + HBr(s) {r_arrow} BrCl + H{sub 2}O(s) on the ice surface at 189 and 220 K has been investigated in a flow reactor interfaced with a differentially pumped quadrupole mass spectrometer. Pseudo first-order decay of HOCl over the HBr-treated ice surfaces has been determined under the condition of P{sub HOCl} < P{sub HBr}. For the HBr partial pressure in the range of 1.1 {times} 10{sup {minus}7} to 6.6 {times} 10{sup {minus}5} Torr, the reaction probability ({gamma}{sub g}) was determined in the range of 0.06 to 0.38 at 189 K. The reaction probability is in the range of 0.01 to 0.07 at 220 K for HBr partial pressure from 7.2 {times} 10{sup {minus}7} to 1.3 {times} 10{sup {minus}5} Torr. The reaction probability was found to be strongly dependent on the ice surface temperature. The reaction probability is higher at the lower temperature than that at the warmer temperature and a mechanistic explanation is provided. The true reaction probabilities ({gamma}{sub t}) of the reaction were calculated using a pore diffusion model. The kinetic analysis indicates that the heterogeneous reaction of HOCl + HBr may follow the Eley-Rideal type of mechanism. Also, the heat of uptake of HOCl on ice was determined to be about {minus}8.5 {+-} 2 kcal/mol.

  18. Use of CO2 laser and AgClBr infrared transmitting fibers for tympanoplasty: experiments on animal models

    NASA Astrophysics Data System (ADS)

    Grundfest, Warren S.

    1999-06-01

    One of the most common ear disease is Chronic Otitis Media that leads to a tympanic membrane perforation. The treatment of this condition is by a surgical procedure, tympanoplasty that is often done under local or general anesthesia. During this procedure an autologous fascia is applied to close the perforation. Commonly, fixation of the fascia is achieved mostly by Gel-Form. During the last several years various fascia fixation techniques were suggested. These included a welding procedure based on using an Argon laser. The disadvantages of the latter is that the visible Argon laser is not absorbed well by the relatively thin tympanic membrane and the fascia. It does not lead to strong weld and it may heat the middle of the ear, causing neural hearing loss. The CO2 laser IR radiation is much more suitable for welding of these thin tissues, because of its very high absorption in tissues. There is still a need to deliver this radiation to the weld site using a thin and flexible optical fiber. In this work we have welded fascia on the tympanic membranes of guinea pigs using a CO2 laser. Holes of diameter 2-3 mm were punctured in the membranes and apiece of fascia was placed on the holes. Laser power of the order of 0.5W was delivered to the fascia using an IR transmitting AgClBr fiber. In experiments done on 11 animals and CO2 laser welding was successfully done on in 15 years. The success of these preliminary studies in the animal models shows that CO2 laser tympanoplasty could be a very valuable surgical technique.

  19. Kinetic smog-chamber studies on halogen activation from a simulated salt pan, using dry and wet NaCl/NaBr surfaces

    NASA Astrophysics Data System (ADS)

    Bleicher, Sergej; Balzer, Natalja; Zetzsch, Cornelius; Buxmann, Joelle; Platt, Ulrich

    2010-05-01

    Field experiments and laboratory studies have shown that atomic Br and Cl are released from sea-salt aerosol and saline soils. This halogen release is based on the uptake of gaseous HOX by aqueous, acidified salt surfaces. Br and Cl play an important role in atmospheric ozone depletion and the destruction of hydrocarbons. Furthermore, Secondary Organic Aerosol (SOA) and HUmic LIke Substances (HULIS) may take part in these reaction cycles by halogenation and production of volatile organic halogen compounds. Aerosol smog-chamber facilities (coolable to -25°C) enable us to simulate the halogen release mechanism under arctic tropospheric conditions. Mechanistic and kinetic studies are carried out to investigate the influence of SOA and HULIS on halogen cycles and to determine halogenated gaseous and solid organic products. The present laboratory measurements study halogen activation from salt surfaces, which are similar to typical salt pan environments. In these experiments we placed different artificial salt mixtures with NaCl/NaBr ratios up to 300:1 on a Teflon pan located in a Teflon chamber with a volume of 3.5 m3. Under clean air conditions we inject ozone and a mixture of non-methane hydrocarbons with well-known reactivities against OH and Cl and irradiated the chamber with a solar simulator. Beside the usual observing instruments like an ozone monitor and a gas chromatograph we used Differential Optical Absorption Spectroscopy (DOAS) in a White cell with a light path up to 320 m to observe various gas-phase species including BrO radicals. A dry air / dry salt pan environment showed no ozone depletion and no halogen activation. At relative humidity above 50%, a rapid ozone depletion (4.7 h half-life) was observed, which is much faster than for pure NaCl under the same conditions (77 h). Furthermore, the mixed salt was acidified with H2SO4 to a pH value of 4.3, no difference in ozone depletion and halogen activation was observed at this point. The DOAS

  20. Double Salts Obtained from Me+X-Cu X2-H 2O Systems ( Me+ = K +, NH +4, rb +, cs +; X- = cl -, br -)

    NASA Astrophysics Data System (ADS)

    Tepavitcharova, St.; Balarew, Chr.; Trendafilova, St.

    1995-02-01

    The solubility diagrams of the Me+ Br-CuBr2-H2O (Me+ = K+, NH+4, Rb+, Cs+) systems are studied. The results obtained are compared with literature data on the corresponding chloride systems in order to estimate the effect of the halide ion (Br- or Cl-) on the solubility diagrams and on the compositions of the double salts formed in these systems. The differences in composition and structure of the double salts are explained by the metal-ligand interactions on the basis of Pearson's concept of hard and soft Lewis acids and bases, as well as by crystal chemistry considerations for the most probable spacial situation of the building elements in the crystal structure.

  1. The Acidity of the HBr/AlBr3 System: Stabilization of Crystalline Protonated Arenes and Their Acidity in Bromoaluminate Ionic Liquids.

    PubMed

    Scholz, Franziska; Himmel, Daniel; Eisele, Lea; Unkrig, Wiebke; Martens, Arthur; Schlüter, Peter; Krossing, Ingo

    2015-05-11

    Bulk protonated mesitylene, toluene, and benzene bromoaluminate salts were stabilized and characterized in the superacidic system HBr/n AlBr3 with NMR spectroscopy and X-ray analysis of [HC6 H3 (CH3 )3 ](+) [AlBr4 ](-) (1), [HC6 H5 (CH3 )](+) [AlBr4 ](-) (2), and [C6 H7 ](+) [Al2 Br7 ](-) ⋅C6 H6 (3). Protonation attempts in bromoaluminate ILs led to a complete protonation of mesitylene, and a protonation degree of up to 15 % for toluene in the IL BMP(+) [Al2 Br7 ](-) . Benzene could only be protonated in the more acidic IL BMP(+) [Al3 Br10 ](-) , with a degree of 25 %. Protonation attempts on aromatics provide evidence that the bromoaluminate ILs tolerate superacidic environments. On the basis of the absolute Brønsted acidity scale, quantum chemical calculations confirmed the superacidic properties, and rank the acidities in ILs down to a pHabs value of 164 with an error of less than one pH unit compared with experimental findings. The neat AlBr3 /HBr system even may reach acidities down to pHabs 163.

  2. Theoretical study of the gas-phase ion pairs SN2 reactions of LiX with CH3SY (X, Y = F, Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Gai, Jing-Gang; Ren, Yi

    The gas-phase ion pair SN2 reactions at saturated sulfur LiX + CH3SY ? CH3SX + LiY (X, Y = F, Cl, Br, I) are investigated using the CCSD(T) calculations. The calculated results show that the reactions LiX + CH3SY are exothermic only when the nucleophile is a heavier lithium halide. Central barrier heights are found to depend primarily on the identity of nucleophile LiX, decreasing in the order LiF > LiCl > LiBr > LiI. Another interesting feature of the ion pair reactions at sulfur is the good correlation between the reaction barriers with geometrical looseness of Li bond X and S bond Y bonds in the transition state structures. The data for the reaction barriers show good agreement with the prediction of the Marcus equation and its modification.

  3. Comprehensive theoretical studies on the low-lying electronic states of NiF, NiCl, NiBr, and NiI.

    PubMed

    Zou, Wenli; Liu, Wenjian

    2006-04-21

    The low-lying electronic states of the nickel monohalides, i.e., NiF, NiCl, NiBr, and NiI, are investigated by using multireference second-order perturbation theory with relativistic effects taken into account. For the energetically lowest 11 lambda-S states and 26 omega states there into, the potential energy curves and corresponding spectroscopic constants (vertical and adiabatic excitation energies, equilibrium bond lengths, vibrational frequencies, and rotational constants) are reported. The calculated results are grossly in very good agreement with those solid experimental data. In particular, the ground state of NiI is shown to be different from those of NiF, NiCl, and NiBr, being in line with the recent experimental observation. Detailed analyses are provided on those states that either have not been assigned or have been incorrectly assigned by previous experiments.

  4. Infrared multiphoton induced isomerization and dissociation of FCN, ClCN, and BrCN in liquid Ar: A classical simulation study

    SciTech Connect

    Zhang Ming; Gong Jiangbin; Ma Ao; Rice, Stuart A.

    2007-10-14

    We report the results of classical mechanics simulations of infrared multiphoton induced control of isomerization of FCN, ClCN, and BrCN in liquid Ar, using ab initio potential energy and dipole moment surfaces for the XCN molecules. The field induced isomerization and fragmentation dynamics of these molecules are found to be different from that of HCN in liquid Ar. In particular, the scheme that provides complete controlled conversion of HCN to CNH in liquid Ar fails to generate complete conversion of XCN to CNX in liquid Ar for X=F,Cl,Br. It is suggested that the sources of the differences in behavior arise from differences in the spectra of vibrational nonlinear resonances in HCN and XCN and to the occurrence of monodromy in the dynamics of the XCN molecules.

  5. Photoelectron spectroscopy of aqueous solutions: streaming potentials of NaX (X = Cl, Br, and I) solutions and electron binding energies of liquid water and X-.

    PubMed

    Kurahashi, Naoya; Karashima, Shutaro; Tang, Ying; Horio, Takuya; Abulimiti, Bumaliya; Suzuki, Yoshi-Ichi; Ogi, Yoshihiro; Oura, Masaki; Suzuki, Toshinori

    2014-05-07

    The streaming potentials of liquid beams of aqueous NaCl, NaBr, and NaI solutions are measured using soft X-ray, He(I), and laser multiphoton ionization photoelectron spectroscopy. Gaseous molecules are ionized in the vicinity of liquid beams and the photoelectron energy shifts are measured as a function of the distance between the ionization point and the liquid beam. The streaming potentials change their polarity with concentration of electrolytes, from which the singular points of concentration eliminating the streaming potentials are determined. The streaming currents measured in air also vanish at these concentrations. The electron binding energies of liquid water and I(-), Br(-), and Cl(-) anions are revisited and determined more accurately than in previous studies.

  6. The effect of atomic ions on model σ-hole bonded complexes of AH3Y (A = C, Si, Ge; Y = F, Cl, Br).

    PubMed

    McDowell, Sean A C; Joseph, Jerelle A

    2014-06-14

    A computational study of ionic X···AH3-Y complexes (X = F(-), Cl(-), Br(-), Li(+), Be(2+); A = C, Si, Ge; Y = F, Cl, Br) predicted optimized structures which are held together by a combination of attractive forces, including ion-dipole and ion-σ-hole electrostatic interactions, and polarization forces. The trends (with variation in the halogen Y) for selected properties were rationalized by considering the electron density shifts due to the ion's electric field. Although it has been found previously that the trends for binding energies in neutral complexes follow the sigma-hole strength, the present study found that the dependence on the dipole polarizability of the A-Y bond can explain the trends for binding energies in these more strongly bound ionic complexes.

  7. Quantifying magnetic exchange in doubly-bridged Cu-X(2)-Cu (X = F, Cl, Br) chains enabled by solid state synthesis of CuF(2)(pyrazine).

    PubMed

    Lapidus, Saul H; Manson, Jamie L; Liu, Junjie; Smith, Matthew J; Goddard, Paul; Bendix, Jesper; Topping, Craig V; Singleton, John; Dunmars, Cortney; Mitchell, J F; Schlueter, John A

    2013-05-04

    Solid state techniques involving pressure and temperature have been used to synthesize the fluoride member of the CuX(2)(pyrazine) (X = F, Cl, Br) family of coordination polymers that cannot be crystallized by solution methods. CuF(2)(pyrazine) exhibits unique trans doubly-bridged Cu-F(2)-Cu chains that provide an opportunity to quantify magnetic superexchange in an isostructural Cu-X(2)-Cu series.

  8. Low coverage spontaneous etching and hyperthermal desorption of aluminum chlorides from Cl2/Al(111).

    PubMed

    Grassman, Tyler J; Poon, Gary C; Kummel, Andrew C

    2004-11-08

    Nonresonant multiphoton ionization with time-of-flight mass spectrometry has been used to monitor the desorption of aluminum chloride (Al(x)Cl(y)) etch products from the Al(111) surface at 100 and 500 K during low-coverage (<5% monolayer) monoenergetic Cl(2) (0.11-0.65 eV) dosing. The desorption products in this low-coverage range show predominantly hyperthermal exit velocities under all dosing conditions. For example, with 0.27 eV incident Cl(2), the etch product was found to have a most-probable velocity of 517+/-22 m/s at an Al(111) surface temperature of 100 K. This corresponds to 22 times the expected thermal desorption translational energy for AlCl(3). Cl(2) sticking probability measurements and Al(x)Cl(y) etch rate measurements show etching even at Cl(2) coverages of less than 5% monolayer at surface temperatures between 100 and 500 K. These experimental results are consistent with a combination of fast-time-scale surface diffusion and agglomeration of the adsorbed chlorine to form aluminum chlorides and the presence of activated AlCl(3) chemisorption states having potential energies above the vacuum level. Density functional theory calculations yield results that are consistent with both our experimental findings and mechanistic descriptions.

  9. LIBS-based detection of As, Br, C, Cl, P, And S in the VUV spectral region in a Mars atmosphere.

    SciTech Connect

    Radziemski, Leon J.,; Cremers, D. A.; Benelli, K. M.; Khoo, C.; Harris, R. D.

    2005-01-01

    Several elements important to planetary geology (e.g. Br, C, Cl, P, S) and the human exploration of Mars (e.g. toxic elements such as As) have strong emission lines in the purge and vacuum ultraviolet (VUV) spectral region (100 to 200 nm). This spectral region has not been extensively studied using geological samples. Prior LIBS work by others examined sulfide mineral indentification and Cl/C and Br/C ratio determinations in organic materials. We studied emissions from the LIBS plasma in this region using a sample chamber filled with 7 torr (930 Pa) of CO{sub 2} to simulate the Martian atmosphere. Lower pressures were also used to evaluate the effect of residual CO{sub 2} on the spectra. The effects of time delay and laser energy on LIBS detection at reduced pressure were examined. The effect of ambient CO{sub 2} on the detection of C in soil was also evaluated. Lines useful for the spectrochemical analysis of As, Br, C, Cl, P, and S were determined, calibration curves prepared, and limits of detection determined for these elements. The experiments reported here were aimed at in-situ (closeup) analysis rather than stand-off detection at many meters.

  10. Synergistic photocatalytic inactivation mechanisms of bacteria by graphene sheets grafted plasmonic AgAgX (X = Cl, Br, I) composite photocatalyst under visible light irradiation.

    PubMed

    Xia, Dehua; An, Taicheng; Li, Guiying; Wang, Wanjun; Zhao, Huijun; Wong, Po Keung

    2016-08-01

    By coupling graphene sheet and plasmonic photocatalysis technologies, a series of AgAgX/RGOs (X = Cl, Br, I; RGO = reduced graphene oxide) composites were prepared and found to be efficient antimicrobial agents for water disinfection upon visible light. Attributed to the efficient charge transfer by RGO sheets, the optimum AgAgBr/0.5% RGO could completely inactivate 2 × 10(7) cfu mL(-1) of Escherichia coli within 8 min, much faster than bare AgAgBr within 35 min. The synergistic antimicrobial mechanism of AgAgBr/0.5% RGO was studied by Ag(+) ions release evaluation, radical scavengers study, and radical determination. The enhanced photocatalytic activity of irradiated AgAgBr/0.5% RGO originated from the synergistic activities of its three components including Ag, AgBr and RGO, and the proposed mechanisms contained enhanced attraction by RGO followed by two pathways: primary oxidative stress caused by plasma induced reactive species like H2O2 and bactericidal effect of released Ag(+) ions. Furthermore, characterization of E. coli cells using SEM, fluorescent microscopy, and cytoplasmic substance leakage illustrated that VL irradiated AgAgBr/0.5% RGO could not only cause metabolic dysfunction but also destroy the cell envelope and biomolecular, while irradiated Ag(+) ions play a differential bactericidal action with a limited metabolic injury and no cell-membrane damage. The present work provides an efficient water disinfection technology and also opens a new idea in studying the antimicrobial mechanism of plasmonic photocatalyst.

  11. Waste-water impacts on groundwater: Cl/Br ratios and implications for arsenic pollution of groundwater in the Bengal Basin and Red River Basin, Vietnam.

    PubMed

    McArthur, J M; Sikdar, P K; Hoque, M A; Ghosal, U

    2012-10-15

    Across West Bengal and Bangladesh, concentrations of Cl in much groundwater exceed the natural, upper limit of 10 mg/L. The Cl/Br mass ratios in groundwaters range up to 2500 and scatter along mixing lines between waste-water and dilute groundwater, with many falling near the mean end-member value for waste-water of 1561 at 126 mg/L Cl. Values of Cl/Br exceed the seawater ratio of 288 in uncommon NO(3)-bearing groundwaters, and in those containing measurable amounts of salt-corrected SO(4) (SO(4) corrected for marine salt). The data show that shallow groundwater tapped by tube-wells in the Bengal Basin has been widely contaminated by waste-water derived from pit latrines, septic tanks, and other methods of sanitary disposal, although reducing conditions in the aquifers have removed most evidence of NO(3) additions from these sources, and much evidence of their additions of SO(4). In groundwaters from wells in palaeo-channel settings, end-member modelling shows that >25% of wells yield water that comprises ≥10% of waste-water. In palaeo-interfluvial settings, only wells at the margins of the palaeo-interfluvial sequence contain detectable waste water. Settings are identifiable by well-colour survey, owner information, water composition, and drilling. Values of Cl/Br and faecal coliform counts are both inversely related to concentrations of pollutant As in groundwater, suggesting that waste-water contributions to groundwater in the near-field of septic-tanks and pit-latrines (within 30 m) suppress the mechanism of As-pollution and lessen the prevalence and severity of As pollution. In the far-field of such sources, organic matter in waste-water may increase groundwater pollution by As.

  12. Potential groundwater age tracer found: Halon-1301 (CF3Br), as previously identified as CFC-13 (CF3Cl)

    NASA Astrophysics Data System (ADS)

    Beyer, Monique; van der Raaij, Rob; Morgenstern, Uwe; Jackson, Bethanna

    2014-09-01

    Groundwater dating using anthropogenic and natural tracer substances is a powerful tool for understanding groundwater dynamics for improved management of groundwater resources. Due to limitations in individual dating methods, often multiple tracers are used to reduce ambiguities. It is commonly accepted that there is a need for further complementary age tracers, in addition to current ones (e.g., tritium, SF6, and CFCs). We propose a potential new groundwater age tracer, Halon-1301 (CF3Br), which can easily be determined using gas chromatography with an attached electron capture detector (GC/ECD) developed by Busenberg and Plummer (2008). Its peak was noted by Busenberg and Plummer (2008), but they believed it to be CFC-13 (CF3Cl) at that time. We performed rigorous tests on gases containing or excluding Halon-1301 and CFC-13 and modern water samples and concluded that the two compounds have extremely similar retention times. Additionally, we found that the ECD response of CFC-13 is far too low to be detected in groundwater or air using standard volumes and sampling techniques. However, the peak areas and concentrations Busenberg and Plummer (2008) reported are in line with what would be expected for Halon-1301. Thus, we are confident that the peak formerly identified as CFC-13 is actually Halon-1301. Busenberg agrees with our findings. We further suggest that Halon-1301 has potential as a (complementary) age tracer, due to its established atmospheric history, and could hypothetically be used to date groundwater recharged in the 1970s or onward. We discuss known relevant properties, such as solubility and stability of Halon-1301 in the context of how these effect its potential application as a groundwater age tracer. Some open questions remain concerning how conservative Halon-1301 is—is it subject to degradation, retardation, and/or local contamination in groundwater. We are confident that Halon-1301 possesses important tracer relevant properties, but further

  13. Broad Wavelength Tunable Robust Lasing from Single-Crystal Nanowires of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I).

    PubMed

    Fu, Yongping; Zhu, Haiming; Stoumpos, Constantinos C; Ding, Qi; Wang, Jue; Kanatzidis, Mercouri G; Zhu, Xiaoyang; Jin, Song

    2016-08-23

    Lead halide perovskite nanowires (NWs) are emerging as a class of inexpensive semiconductors with broad bandgap tunability for optoelectronics, such as tunable NW lasers. Despite exciting progress, the current organic-inorganic hybrid perovskite NW lasers suffer from limited tunable wavelength range and poor material stability. Herein, we report facile solution growth of single-crystal NWs of inorganic perovskite CsPbX3 (X = Br, Cl) and their alloys [CsPb(Br,Cl)3] and a low-temperature vapor-phase halide exchange method to convert CsPbBr3 NWs into perovskite phase CsPb(Br,I)3 alloys and metastable CsPbI3 with well-preserved perovskite crystal lattice and NW morphology. These single crystalline NWs with smooth end facets and subwavelength dimensions are ideal Fabry-Perot cavities for NW lasers. Optically pumped tunable lasing across the entire visible spectrum (420-710 nm) is demonstrated at room temperature from these NWs with low lasing thresholds and high-quality factors. Such highly efficient lasing similar to what can be achieved with organic-inorganic hybrid perovskites indicates that organic cation is not essential for light emission application from these lead halide perovskite materials. Furthermore, the CsPbBr3 NW lasers show stable lasing emission with no measurable degradation after at least 8 h or 7.2 × 10(9) laser shots under continuous illumination, which are substantially more robust than their organic-inorganic counterparts. The Cs-based perovskites offer a stable material platform for tunable NW lasers and other nanoscale optoelectronic devices.

  14. Reinvestigation of the laser-initiated Cl/sub 2//HBr chain reaction: absolute rate constants and the v = 2/v = 1 ratio from Cl + HBr. -->. HCl(v) + Br

    SciTech Connect

    Dolson, D.A.; Leone, S.R.

    1987-06-18

    The Cl/sub 2//HBr chain reaction is reinvestigated by using real time state-selected observations of ..delta..v = -1 chemiluminescence from the HCl(V) products following pulsed laser photolysis of Cl/sub 2/. These state-selected observations are analyzed with a more complete kinetic treatment to obtain room temperature rate constants for the chain propagation steps and the vibrational deactivation of HCl(V = 1,2) by HBr. The chain propagation rate constants are k/sub R1/ = (1.02 +/- 0.15) x 10/sup -11/ and k/sub R2/ = (1.1 +/- 0.4) x 10/sup -15/ cm/sup 3/ molecule/sup -1/ s/sup -1/, respectively, for Cl + HBr ..-->../sup kR1/ HCl(v) + Br and Br + Cl/sub 2/ ..-->../sup kR2/ BrCl + Cl. Rate constants for vibrational deactivation of HCl(v=1) and HCl(v=2) by HBr are k/sub V1/ = (1.06 +/- 0.16) x 10/sup -12/ and k/sub V2/ = (2.09 +/- 0.50) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/. Relative intensity measurements of the HCl v = 2 ..-->.. 1 and 1 ..-->.. 0 vibrational fluorescence are used to obtain an HCl(v) product branching ratio, N/sub v=2//N/sub v=1/ = 0.40 +/- 0.06. The kinetic analysis indicates that broad-band observations of infrared chemiluminescence may lead to erroneous rate constant determinations because of vibrational cascade, whereas the detection of individual vibrational states leads to correct results.

  15. Theoretical Study of Electronic Properties of X-Doped (X = F, Cl, Br, I) VO2 Nanoparticles for Thermochromic Energy-Saving Foils.

    PubMed

    Ren, Qinghua; Wan, Jinyu; Gao, Yanfeng

    2014-11-20

    First-principles density functional theory (DFT) electronic structure calculations were carried out for the model halogen-doped VO2 (M1 phase) to evaluate the effect of halogen (X = F, Cl, Br, I) doping on the band edges. The model structures of X-doped VO2 with X at V site or O site were constructed on the basis of 96-atom 2 × 2 × 2 supercell of monoclinic M1 phase of VO2. Our results showed that the band gap Eg2 for Cl-doped VO2 at O1 site (0.51 eV) is smaller than that of F-doped VO2 at O1 site (0.61 eV) and that of pure VO2 (0.78 eV). We also investigated the substitution of chlorine, bromine, and iodine for vanadium in VO2, where the band gaps Eg2 are 0.40, 0.45, and 0.37 eV for Cl-, Br-, and I-doped VO2 at V site, respectively. The Cl-doped VO2 at V site is the best one for achieving good VO2 thermochromic energy-saving foils.

  16. Technical note: Interference of Br{sup {minus}}, BrO{sub 3}{sup {minus}}, and ClO{sub 3}{sup {minus}} with DOX determination

    SciTech Connect

    Symons, J.M.; Xia, R.

    1995-08-01

    In the dissolved organic halogen (DOX) water quality analytic test, prior to combustion, the granular activated carbon (GAC) on which the DOX is adsorbed is washed with a sodium nitrate solution designed to remove any inorganic chloride that may have also adsorbed to the GAC. Thus, a potential positive interference is removed. This study investigated the effectiveness of the nitrate wash in eliminating possible interferences from bromide, bromate, and chlorate ions. No interference was detected from bromate or chlorate ion, but a small positive interference of about 12 {micro}g Cl{sup {minus}}/L per mg/L of bromide ion was found in the presence of background organic matter.

  17. TeX4 (X = F, Cl, Br) as Lewis acids--complexes with soft thio- and seleno-ether ligands.

    PubMed

    Hector, Andrew L; Jolleys, Andrew; Levason, William; Reid, Gillian

    2012-08-28

    TeF(4) reacts with OPR(3) (R = Me or Ph) in anhydrous CH(2)Cl(2) to give the colourless, square based pyramidal 1 : 1 complexes [TeF(4)(OPR(3))] only, in which the OPR(3) is coordinated basally in the solid state, (R = Me: d(Te-O) = 2.122(2) Å; R = Ph: d(Te-O) = 2.1849(14) Å). Variable temperature (19)F{(1)H}, (31)P{(1)H} and (125)Te{(1)H} NMR spectroscopic studies strongly suggest this is the low temperature structure in solution, although the systems are dynamic. The much softer donor ligands SMe(2) and SeMe(2) show a lower affinity for TeF(4), although unstable, yellow products with spectroscopic features consistent with [TeF(4)(EMe(2))] are obtained by the reaction of TeF(4) in neat SMe(2) or via reaction in CH(2)Cl(2) with SeMe(2). TeX(4) (X = F, Cl or Br) causes oxidation and halogenation of TeMe(2) to form X(2)TeMe(2). The Br(2)TeMe(2) hydrolyses in trace moisture to form [BrMe(2)Te-O-TeMe(2)Br], the crystal structure of which has been determined. TeX(4) (X = Cl or Br) react with the selenoethers SeMe(2), MeSe(CH(2))(3)SeMe or o-C(6)H(4)(SeMe)(2) (X = Cl) in anhydrous CH(2)Cl(2) to give the distorted octahedral monomers trans-[TeX(4)(SeMe(2))(2)], cis-[TeX(4){MeSe(CH(2))(3)SeMe}] and cis-[TeCl(4){o-C(6)H(4)(SeMe)(2)}], which have been characterised by IR, Raman and multinuclear NMR ((1)H, (77)Se{(1)H} and (125)Te{(1)H}) spectroscopy, and via X-ray structure determinations of representative examples. Tetrahydrothiophene (tht) can form both 1 : 1 and 1 : 2 Te : L complexes. For X = Br, the former has been shown to be a Br-bridged dimer, [Br(3)(tht)Te(μ-Br)(2)TeBr(3)(tht)], by crystallography with the tht ligands anti, whereas the latter are trans-octahedral monomers. Like its selenoether analogue, MeS(CH(2))(3)SMe forms distorted octahedral cis-chelates, [TeX(4){MeS(CH(2))(3)SMe}], whereas the more rigid o-C(6)H(4)(SMe)(2) unexpectedly forms a zig-zag chain polymer in the solid state, [TeCl(4){o-C(6)H(4)(SMe)(2)}](n), in which the dithioether adopts an

  18. Interplay between Beryllium Bonds and Anion-π Interactions in BeR2:C6X6:Y- Complexes (R = H, F and Cl, X = H and F, and Y = Cl and Br).

    PubMed

    Marín-Luna, Marta; Alkorta, Ibon; Elguero, José; Mó, Otilia; Yáñez, Manuel

    2015-05-29

    A theoretical study of the beryllium bonds in BeR2:C6X6 (R = H, F, Cl and X = H and F) has been carried out by means of MP2/aug'-cc-pVDZ computational methods. In addition, the ternary complexes BeR2:C6X6:Y- (Y = Cl and Br) have been analyzed. Geometric, energetic and electronic aspects of the complexes have been taken into account. All the parameters analyzed provide a clear indication of favorable cooperativity in both interactions observed, beryllium bond and aromatic ring:anion interaction.

  19. Electron attachment and detachment: C6 F5 Cl , C6 F5 Br , and C6 F5 I and the electron affinity of C6 F5 Cl

    NASA Astrophysics Data System (ADS)

    Miller, Thomas M.; Viggiano, A. A.

    2005-01-01

    Measurements are reported of rate constants for electron attachment to C6F5X (X=Cl,Br,I) and thermal electron detachment from C6F5Cl- over the temperature range 300-550K in 133Pa of He gas in a flowing-afterglow Langmuir-probe apparatus. This is the first case we know of where the parent anion has sufficiently low electron detachment energy that detachment (from C6F5Cl- in this case) has been observed in competition with a channel for dissociative electron attachment yielding a thermally stable anion (here, Cl- ). Because of this competition, it is shown that a simple mass spectrometric determination of the product branching fractions at long times will lead to erroneous results at elevated temperatures. The electron density profiles provide evidence for a new plasma decay process involving the detaching and nondetaching anions trapped in the space charge field of the positive ions. Electron attachment rate constants were found to be 1.0×10-7 , 1.1×10-7 , and 2.0×10-7cm3s-1 , at 300K , for C6F5Cl , C6F5Br , and C6F5I , respectively, estimated accurate to ±25% except for C6F5I , where there is ±30% uncertainty. Rate constants for C6F5Cl changed little over our temperature range, while those for C6F5Br , and C6F5I increased with temperature. Electron detachment occurred only for C6F5Cl- in our temperature range. Detachment rate constants were immeasurable at room temperature but approached 4000s-1 at 550K . From these data the electron affinity (EA) for C6F5Cl was determined, EA (C6F5Cl)=0.75±0.08eV . G3(MP2) calculations (based on Møller-Plesset perturbation theory) were carried out for the neutral and anion and yielded EA(C6F5Cl)=0.728eV .

  20. X-ray photoelectron spectroscopy of fast-frozen hematite colloids in aqueous solutions. 5. Halide ion (F-, Cl-, Br-, I-) adsorption.

    PubMed

    Shimizu, Kenichi; Shchukarev, Andrey; Kozin, Philipp A; Boily, Jean-François

    2013-02-26

    Halide anion (F(-), Cl(-), Br(-), and I(-)) adsorption and its impact on sodium adsorption at the hematite/water interface were studied by cryogenic X-ray photoelectron spectroscopy (XPS). Measurements were carried out on frozen, centrifuged wet hematite pastes that were previously equilibrated in 50 mM electrolytic solutions in the pH 2-11 range. XPS-derived halide ion surface loadings decreased in the order F(-) > I(-) ≈ Cl(-) > Br(-), whereas sodium loadings were in the order Na(F) > Na(I) > Na(Br) > Na(Cl). The greater sodium loadings in NaF and in NaI resulted from larger anion loadings in these systems. Bromide ion had the lowest loading among all halide ions despite having a charge-to-size ratio that is intermediate between those of Cl(-) and I(-). This unexpected result may have arisen from specific properties of the hematite/water interface, such as water structure and electric double layer thickness. Fluoride ion adsorption proceeded via the formation of hydrogen bonds with the surface hydroxo groups (e.g., ≡Fe-OH(2)···F(-) or ≡Fe-OH···F(-)). Surface-bound fluoride ions exert a greater charge-screening effect than the other halide anions, as demonstrated by considerably small zeta potential values. Fe-F bond formation was excluded as a possible interfacial process as the F 1s peak binding energy (684.2 eV) was more comparable to that of NaF (684.6 eV) than FeF(3) (685.4 eV). Overall, these findings motivate further refinements of existing thermodynamic adsorption models for predicting the ionic composition of hematite particle surfaces contacted with sodium halide aqueous solutions.

  1. An ab initio investigation of the ground and low-lying singlet and triplet electronic states of XNO{sub 2} and XONO (X = Cl, Br, and I)

    SciTech Connect

    Peterson, Kirk A.; Francisco, Joseph S.

    2014-01-28

    A systematic ab initio treatment of the nitryl halides (XNO{sub 2}) and the cis- and trans- conformers of the halide nitrites (XONO), where X = Cl, Br, and I, have been carried out using highly correlated methods with sequences of correlation consistent basis sets. Equilibrium geometries and harmonic frequencies have been accurately calculated in all cases at the explicitly correlated CCSD(T)-F12b level of theory, including the effects of core-valence correlation for the former. Where experimental values are available for the equilibrium structures (ClNO{sub 2} and BrNO{sub 2}), the present calculations are in excellent agreement; however, the X-O distances are slightly too long by about 0.01 Å due to missing multireference effects. Accurate predictions for the iodine species are made for the first time. The vertical electronic excitation spectra have been calculated using equation-of-motion coupled cluster methods for the low-lying singlet states and multireference configuration interaction for both singlet and triplet states. The latter also included the effects of spin-orbit coupling to provide oscillator strengths for the ground state singlet to excited triplet transitions. While for ClNO{sub 2} the transitions to excited singlet states all occur at wavelengths shorter than 310 nm, there is one longer wavelength singlet transition in BrNO{sub 2} and two in the case of INO{sub 2}. The long wavelength tail in the XNO{sub 2} species is predicted to be dominated by transitions to triplet states. In addition to red-shifting from X = Cl to I, the triplet transitions also increase in oscillator strength, becoming comparable to many of the singlet transitions in the case of INO{sub 2}. Hence in particular, the latter species should be very photolabile. Similar trends are observed and reported for the halogen nitrites, many of which for the first time.

  2. Phosphenium Hydride Reduction of [(cod)MX2] (M = Pd, Pt; X = Cl, Br): Snapshots on the Way to Phosphenium Metal(0) Halides and Synthesis of Metal Nanoparticles.

    PubMed

    Nickolaus, Jan; Imbrich, Dominik A; Schlindwein, Simon H; Geyer, Adrian H; Nieger, Martin; Gudat, Dietrich

    2017-03-06

    The outcome of the reduction of [(cod)PtX2] (X = Cl, Br; cod = 1,5-cyclooctadiene) with N-heterocyclic phosphenium hydrides (R)NHP-H depends strongly on the steric demand of the N-aryl group R and the nature of X. Reaction of [(cod)PtCl2] with (Dipp)NHP-H featuring bulky N-Dipp groups produced an unprecedented monomeric phosphenium metal(0) halide [((Dipp)NHP)((Dipp)NHP-H)PtCl] stabilized by a single phosphine ligand. The phosphenium unit exhibits a pyramidal coordination geometry at the phosphorus atom and may according to DFT calculations be classified as a Z-type ligand. In contrast, reaction of [(cod)PtBr2] with the sterically less protected (Mes)NHP-H afforded a mixture of donor-ligand free oligonuclear complexes [{((Mes)NHP)PtBr}n] (n = 2, 3), which are structural analogues of known palladium complexes with μ2-bridging phosphenium units. All reductions studied proceed via spectroscopically detectable intermediates, several of which could be unambiguously identified by means of multinuclear ((1)H, (31)P, (195)Pt) NMR spectroscopy and computational studies. The experimental findings reveal that the phosphenium hydrides in these multistep processes adopt a dual function as ligands and hydride transfer reagents. The preference for the observed intricate pathways over seemingly simpler ligand exchange processes is presumably due to kinetic reasons. The attempt to exchange the bulky phosphine ligand in [((Dipp)NHP)((Dipp)NHP-H)PtCl] by Me3P resulted in an unexpected isomerization to a platinum(0) chlorophosphine complex via a formal chloride migration from platinum to phosphorus, which accentuates the electrophilic nature of the phosphenium ligand. Phosphenium metal(0) halides of platinum further show a surprising thermal stability, whereas the palladium complexes easily disintegrate upon gentle heating in dimethyl sulfoxide to yield metal nanoparticles, which were characterized by TEM and XRD studies.

  3. Thermal Expansion Behavior of M(I)[AuX2(CN)2]-Based Coordination Polymers (M = Ag, Cu; X = CN, Cl, Br).

    PubMed

    Ovens, Jeffrey S; Leznoff, Daniel B

    2017-04-04

    Two sets of trans-[AuX2(CN)2](-)-based coordination polymer materials-M[AuX2(CN)2] (M = Ag; X = Cl, Br or M = Cu; X = Br) and M[Au(CN)4] (M = Ag, Cu)-were synthesized and structurally characterized and their dielectric constants and thermal expansion behavior explored. The M[AuX2(CN)2] series crystallized in a tightly packed, mineral-like structure featuring 1-D trans-[AuX2(CN)2](-)-bridged chains interconnected via a series of intermolecular Au···X and M···X (M = Ag, Cu) interactions. The M[Au(CN)4] series adopted a 2-fold interpenetrated 3-D cyano-bound framework lacking any weak intermolecular interactions. Despite the tight packing and the presence of intermolecular interactions, these materials exhibited decreased thermal stability over unbound trans-[AuX2(CN)2](-) in [(n)Bu4N][AuX2(CN)2]. A significant dielectric constant of up to εr = 36 for Ag[AuCl2(CN)2] (1 kHz) and a lower εr = 9.6 (1 kHz) for Ag[Au(CN)4] were measured and interpreted in terms of their structures and composition. A systematic analysis of the thermal expansion properties of the M[AuX2(CN)2] series revealed a negative thermal expansion (NTE) component along the cyano-bridged chains with a thermal expansion coefficient (αCN) of -13.7(11), -14.3(5), and -11.36(18) ppm·K(-1) for Ag[AuCl2(CN)2], Ag[AuBr2(CN)2], and Cu[AuBr2(CN)2], respectively. The Au···X and Ag···X interactions affect the thermal expansion similarly to metallophilic Au···Au interactions in M[Au(CN)2] and AuCN; replacing X = Cl with the larger Br atoms has a less significant effect. A similar analysis for the M[Au(CN)4] series (where the volume thermal expansion coefficient, αV, is 41(3) and 68.7(19) ppm·K(-1) for M = Ag, Cu, respectively) underscored the significance of the effect of the atomic radius on the flexibility of the framework and, thus, the thermal expansion properties.

  4. Nanocrystals of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut

    PubMed Central

    2015-01-01

    Metal halides perovskites, such as hybrid organic–inorganic CH3NH3PbI3, are newcomer optoelectronic materials that have attracted enormous attention as solution-deposited absorbing layers in solar cells with power conversion efficiencies reaching 20%. Herein we demonstrate a new avenue for halide perovskites by designing highly luminescent perovskite-based colloidal quantum dot materials. We have synthesized monodisperse colloidal nanocubes (4–15 nm edge lengths) of fully inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I or mixed halide systems Cl/Br and Br/I) using inexpensive commercial precursors. Through compositional modulations and quantum size-effects, the bandgap energies and emission spectra are readily tunable over the entire visible spectral region of 410–700 nm. The photoluminescence of CsPbX3 nanocrystals is characterized by narrow emission line-widths of 12–42 nm, wide color gamut covering up to 140% of the NTSC color standard, high quantum yields of up to 90%, and radiative lifetimes in the range of 1–29 ns. The compelling combination of enhanced optical properties and chemical robustness makes CsPbX3 nanocrystals appealing for optoelectronic applications, particularly for blue and green spectral regions (410–530 nm), where typical metal chalcogenide-based quantum dots suffer from photodegradation. PMID:25633588

  5. Studies of the EPR g factor for Ni2+ ion in CsMgX3 (X=Cl, Br, I) crystals.

    PubMed

    Zheng, Wen-Chen; Wu, Xiao-Xuan

    2006-06-01

    The complete high-order perturbation formula of g factor, including not only the widely used crystal-field (CF) mechanism, but also the neglected change-transfer (CT) mechanism in the CF theory, is established for a 3d8 ion in cubic octahedral site. From the formula, the g-shifts Deltag (=g-gs, where gs approximately 2.0023, the value of free electron) of Ni2+ ion in CsMgX3 (X=Cl, Br, I) crystals are calculated. The results suggest that the g-shift DeltagCT due to the CT mechanism and the DeltagCF due to CF mechanism have the same sign and the importance of DeltagCT follows the order: CsMgI3: Ni2+>CsMgBr3: Ni2+>CsMgCl3: Ni2+. So, in the calculations of g or Deltag of 3dn MXm clusters in crystals, the contributions to g factor from both the CT and CF mechanisms should be taken into account in the case of heavy-element ligand ions, such as Br- and I- ions.

  6. Nanocrystals of Cesium Lead Halide Perovskites (CsPbX₃, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut.

    PubMed

    Protesescu, Loredana; Yakunin, Sergii; Bodnarchuk, Maryna I; Krieg, Franziska; Caputo, Riccarda; Hendon, Christopher H; Yang, Ruo Xi; Walsh, Aron; Kovalenko, Maksym V

    2015-06-10

    Metal halides perovskites, such as hybrid organic-inorganic CH3NH3PbI3, are newcomer optoelectronic materials that have attracted enormous attention as solution-deposited absorbing layers in solar cells with power conversion efficiencies reaching 20%. Herein we demonstrate a new avenue for halide perovskites by designing highly luminescent perovskite-based colloidal quantum dot materials. We have synthesized monodisperse colloidal nanocubes (4-15 nm edge lengths) of fully inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I or mixed halide systems Cl/Br and Br/I) using inexpensive commercial precursors. Through compositional modulations and quantum size-effects, the bandgap energies and emission spectra are readily tunable over the entire visible spectral region of 410-700 nm. The photoluminescence of CsPbX3 nanocrystals is characterized by narrow emission line-widths of 12-42 nm, wide color gamut covering up to 140% of the NTSC color standard, high quantum yields of up to 90%, and radiative lifetimes in the range of 1-29 ns. The compelling combination of enhanced optical properties and chemical robustness makes CsPbX3 nanocrystals appealing for optoelectronic applications, particularly for blue and green spectral regions (410-530 nm), where typical metal chalcogenide-based quantum dots suffer from photodegradation.

  7. Eu(2+)-Activated Alkaline-Earth Halophosphates, M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) for NUV-LEDs: Site-Selective Crystal Field Effect.

    PubMed

    Kim, Donghyeon; Kim, Sung-Chul; Bae, Jong-Seong; Kim, Sungyun; Kim, Seung-Joo; Park, Jung-Chul

    2016-09-06

    Eu(2+)-activated M5(PO4)3X (M = Ca, Sr, Ba; X = F, Cl, Br) compounds providing different alkaline-earth metal and halide ions were successfully synthesized and characterized. The emission peak maxima of the M5(PO4)3Cl:Eu(2+) (M = Ca, Sr, Ba) compounds were blue-shifted from Ca to Ba (454 nm for Ca, 444 nm for Sr, and 434 nm for Ba), and those of the Sr5(PO4)3X:Eu(2+) (X = F, Cl, Br) compounds were red-shifted along the series of halides, F → ClBr (437 nm for F, 444 nm for Cl, and 448 nm for Br). The site selectivity and occupancy of the activator ions (Eu(2+)) in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) crystal lattices were estimated based on theoretical calculation of the 5d → 4f transition energies of Eu(2+) using LCAO. In combination with the photoluminescence measurements and theoretical calculation, it was elucidated that the Eu(2+) ions preferably enter the fully oxygen-coordinated sites in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) compounds. This trend can be well explained by "Pauling's rules". These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field.

  8. Four new chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl: Syntheses, crystal structures and optical properties

    SciTech Connect

    Li, Chao; Feng, Kai; Tu, Heng; Yao, Jiyong; Wu, Yicheng

    2015-07-15

    Four new chalcohalides, namely NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br, and CsBa{sub 2}SnS{sub 4}Cl, have been synthesized by the conventional high temperature solid-state reactions. They crystallize in three different space groups: space group I4/mcm for NaBa{sub 2}SnS{sub 4}Cl and KBa{sub 2}SnS{sub 4}Cl, Pnma for KBa{sub 2}SnS{sub 4}Br, and P2{sub 1}/c for CsBa{sub 2}SnS{sub 4}Cl. In all four compounds, the X{sup −} halide anions are only connected to six alkali metal or Ba cations, and the Sn atoms are only tetrahedrally enjoined to four S atoms. However, the M–X–Ba pseudo layers and the SnS{sub 4} tetrahedra are arranged in different ways in the three structural types, which demonstrates the interesting effect of ionic radii on the crystal structures. UV–vis–NIR spectroscopy measurements indicate that NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br, and CsBa{sub 2}SnS{sub 4}Cl have band gaps of 2.28, 2.30, 1.95, and 2.06 eV, respectively. - Graphical abstract: A new series of chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have been obtained. They present three different space groups: NaBa{sub 2}SnS{sub 4}Cl and KBa{sub 2}SnS{sub 4}Cl in space group I4/mcm, KBa{sub 2}SnS{sub 4}Br in Pnma and CsBa{sub 2}SnS{sub 4}Cl in space group P2{sub 1}/c. UV–vis–NIR spectroscopy measurements indicate that NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have band gaps of 2.28, 2.30 1.95, and 2.06 eV, respectively. - Highlights: • Four new chalcohalides, NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl were obtained. • They adopt three different structures owing to different ionic radii and elemental electronegativity. • NaBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Cl, KBa{sub 2}SnS{sub 4}Br and CsBa{sub 2}SnS{sub 4}Cl have band gaps

  9. Brightly Luminescent and Color-Tunable Colloidal CH3NH3PbX3 (X = Br, I, Cl) Quantum Dots: Potential Alternatives for Display Technology.

    PubMed

    Zhang, Feng; Zhong, Haizheng; Chen, Cheng; Wu, Xian-gang; Hu, Xiangmin; Huang, Hailong; Han, Junbo; Zou, Bingsuo; Dong, Yuping

    2015-04-28

    Organometal halide perovskites are inexpensive materials with desirable characteristics of color-tunable and narrow-band emissions for lighting and display technology, but they suffer from low photoluminescence quantum yields at low excitation fluencies. Here we developed a ligand-assisted reprecipitation strategy to fabricate brightly luminescent and color-tunable colloidal CH3NH3PbX3 (X = Br, I, Cl) quantum dots with absolute quantum yield up to 70% at room temperature and low excitation fluencies. To illustrate the photoluminescence enhancements in these quantum dots, we conducted comprehensive composition and surface characterizations and determined the time- and temperature-dependent photoluminescence spectra. Comparisons between small-sized CH3NH3PbBr3 quantum dots (average diameter 3.3 nm) and corresponding micrometer-sized bulk particles (2-8 μm) suggest that the intense increased photoluminescence quantum yield originates from the increase of exciton binding energy due to size reduction as well as proper chemical passivations of the Br-rich surface. We further demonstrated wide-color gamut white-light-emitting diodes using green emissive CH3NH3PbBr3 quantum dots and red emissive K2SiF6:Mn(4+) as color converters, providing enhanced color quality for display technology. Moreover, colloidal CH3NH3PbX3 quantum dots are expected to exhibit interesting nanoscale excitonic properties and also have other potential applications in lasers, electroluminescence devices, and optical sensors.

  10. The effect of NaCl/g/ on the oxidation of NiAl

    NASA Technical Reports Server (NTRS)

    Smeggil, J. G.; Bornstein, N. S.

    1978-01-01

    NaCl is ingested into operating gas turbines. The effect of this salt on the high temperature surface stability properties of turbine hardware is not well understood. The involvement of gaseous NaCl in the high temperature oxidation of NiAl, a principal component in many high temperature environmental coatings, is herein examined. The results of this work indicate that gaseous NaCl present in an oxidizing atmosphere affects the formation of Al2O3 whiskers on a dense Al2O3 layer. Such whisker growth, attributed to vapor transport processes through an otherwise dense Al2O3 scale, increases the aluminum depletion of the NiAl substrate.

  11. Al-Cd Alloy Formation by Aluminum Underpotential Deposition from AlCl3+NaCl Melts on Cadmium Substrate

    NASA Astrophysics Data System (ADS)

    Jovićević, Niko; Cvetković, Vesna S.; Kamberović, Željko J.; Jovićević, Jovan N.

    2013-02-01

    Aluminum was incorporated into a polycrystalline cadmium electrode surface by underpotential deposition from equimolar AlCl3+ NaCl melt at 473 K, 523 K, and 573 K (200 °C, 250 °C, and 300 °C). The process was studied by linear sweep voltammetry and potentiostatic deposition/galvanostatic striping. The deposits were characterized X-ray diffraction (XRD), Auger electron spectroscopy (AES), and electron probe microanalyzer (EPMA). The electrochemical measurements showed evidence of Cd-Al alloys being formed but they could not be identified. The growth kinetics of the Cd-Al layers of various proportion and depths that depended on temperature and deposition time were described.

  12. The synthesis, activity, stability and the charge transfer identification of Ag:AgBr/γ-Al2O3 photocatalyst for organic pollutant decomposition in water

    NASA Astrophysics Data System (ADS)

    Huang, Shan; Si, Zhichun; Weng, Duan

    2015-12-01

    Highly stable Ag:AgBr/γ-Al2O3 photo-catalyst was obtained by dispersing AgBr sol on hollow γ-Al2O3 microsphere. Metallic Ag nanoparticles were in situ generated on AgBr crystals by a photo-reduction method. The activity of catalyst was characterized by MO and phenol decomposition. The light irradiation response, the life times of the photo-induced charges, and the charge separation and transition were determined by the UV-vis diffuse reflection spectra, open circuit voltage decay spectra and transient photocurrent responses. The as-prepared Ag:AgBr/γ-Al2O3 catalyst can response to visible light irradiation. Charge separation was clarified to correlate with electrons transferring from Ag to AgBr surface and the consequent reaction with ads-O2 to generate rad O2- species. It was found that the rad O2- rather than rad OH played a dominant role in the photocatalytic oxidation of MO and phenol in water. However, the electrons trended to transfer from AgBr to Ag intrinsically without light irradiation. Therefore, the electron transfer between Ag and AgBr reaching the dynamic equilibrium was the key factor for obtaining a high stable Ag/AgBr catalyst which can be obtained by optimizing the Ag:AgBr ratio. Loading amount of Ag:AgBr on γ-Al2O3 was optimized to 30 wt.% and the metallic Ag content was stabilized at 9 wt.% of Ag:AgBr catalyst.

  13. Neutron inelastic scattering investigation of the magnetic excitations in Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2} (X=Br,Cl)

    SciTech Connect

    Crowe, S.J.; Majumdar, S.; Lees, M.R.; Paul, D. McK.; Bewley, R.I.; Levett, S.J.; Ritter, C.

    2005-06-01

    Neutron inelastic scattering investigations have been performed on the spin tetrahedral system Cu{sub 2}Te{sub 2}O{sub 5}X{sub 2} (X=Cl,Br). We report the observation of magnetic excitations with a dispersive component in both compounds, associated with the three-dimensional incommensurate magnetic order that develops below T{sub N}{sup Cl}=18.2 K and T{sub N}{sup Br}=11.4 K. The excitation in Cu{sub 2}Te{sub 2}O{sub 5}Cl{sub 2} softens as the temperature approaches T{sub N}{sup Cl}, leaving diffuse quasi-elastic scattering above the transition temperature. In the bromide, the excitations are present well above T{sub N}{sup Br}, which might be attributed to the presence of a degree of low dimensional correlations above T{sub N}{sup Br} in this compound.

  14. Room-temperature scintillation properties of cerium-doped REOX (RE=Y, La, Gd, and Lu; X=F, Cl, Br, and I)

    SciTech Connect

    Eagleman, Yetta; Bourret-Courchesne, Edith; Derenzo, Stephen

    2010-12-10

    The scintillation properties of cerium-doped oxyhalides following the general formula REOX (RE=Y, La, Gd, and Lu; X=F, Cl, Br, and I) are reported. These materials were synthesized under dry conditions as microcrystalline powders from conventional solid state reactions. The room temperature X-ray excited emission and scintillation decay curves were measured and analyzed for each material. Additionally, the hygroscopic nature of the oxychlorides and oxybromides was compared to that of their corresponding rare earth halides. The yttrium, lanthanum, and gadolinium oxychlorides, and all of the oxybromides and oxyiodides are found to be activated by Ce{sup 3+}. GdOBr doped with 0.5% Ce{sup 3+} has the highest light output with a relative luminosity of about one-half that of LaBr{sub 3}: Ce{sup 3+}. It displays a single exponential decay of 30 ns.

  15. The C-Cl⋯N halogen bond, the weaker relative of the C-I and C-Br⋯N halogen bonds, finally characterized in solution

    NASA Astrophysics Data System (ADS)

    Hauchecorne, Dieter; van der Veken, Benjamin J.; Moiana, Alessio; Herrebout, Wouter A.

    2010-08-01

    The formation of halogen bonded complexes between trimethylamine (TMA) and the trifluoro halomethanes CF 3I, CF 3Br and CF 3Cl dissolved in liquid xenon, krypton and argon, respectively, has been investigated using FTIR spectroscopy. For all Lewis acids, evidence was found for the formation of C-X⋯N halogen bonded 1:1 complexes. This study provides the first experimental characterization of a complex formed under thermodynamic equilibrium conditions in solution via a C-Cl⋯N halogen bond. Using spectra recorded at different temperatures, the complexation enthalpies for the complexes were determined to be -28.7(1) kJ mol -1 (CF 3I ·TMA), -18.3(1) kJ mol -1 (CF 3Br ·TMA) and -8.9(2) kJ mol -1 (CF 3Cl ·TMA). The results from the cryospectroscopic study are compared with ab initio calculations at the MP2/6-311++G(d,p) + LanL2DZ∗ level.

  16. Photoluminescent mixed ligand complexes of CuX (X = Cl, Br, I) with PPh3 and a polydentate imino-pyridyl ligand - Syntheses, structural variations and catalytic property

    NASA Astrophysics Data System (ADS)

    Ghorai, Anupam; Mondal, Jahangir; Patra, Goutam K.

    2015-10-01

    Three ternary copper(I) complexes [CuI2Cl2(L1)(PPh3)4] (1), [CuI2Br2(L1) (PPh3)4] (2) and [CuI2(μ-I)2 (μ-L1) (PPh3)2]n (3) have been prepared by reactions of CuX (X = Cl, Br and I) with PPh3 and the polydentate imino-pyridyl ligand L1. These complexes have been characterized by elemental analysis, IR, UV-Vis, NMR and X-ray crystallography. From single crystal structural analysis it has been found that complexes 1 and 2 are homo-dinuclear having non-bridging halide ions whereas complex 3 is a 1-D zig-zag co-ordination polymer containing bridged iodide ions. Complexes 1, 2 and 3 are photoluminescent at room temperature in chloroform whereas ligand L1 is non-emissive. The E½ values of the CuIsbnd CuII couple of 1, 2 and 3 are 0.98 V, 0.92 V and 0.42 V respectively (vs Ag/AgCl in 1 M KCl, scan rate 100 mV s-1). All three complexes function as effective catalysts for the synthesis of 2-substituted benzoxazoles.

  17. Synthetic cannabinoid JWH-018 and its halogenated derivatives JWH-018-Cl and JWH-018-Br impair Novel Object Recognition in mice: Behavioral, electrophysiological and neurochemical evidence.

    PubMed

    Barbieri, M; Ossato, A; Canazza, I; Trapella, C; Borelli, A C; Beggiato, S; Rimondo, C; Serpelloni, G; Ferraro, L; Marti, M

    2016-10-01

    It is well known that an impairment of learning and memory function is one of the major physiological effects caused by natural or synthetic cannabinoid consumption in rodents, nonhuman primates and in humans. JWH-018 and its halogenated derivatives (JWH-018-Cl and JWH-018-Br) are synthetic CB1/CB2 cannabinoid agonists, illegally marketed as "Spice" and "herbal blend" for their Cannabis-like psychoactive effects. In the present study the effects of acute exposure to JWH-018, JWH-018-Cl, JWH-018-Br (JWH-018-R compounds) and Δ(9)-THC (for comparison) on Novel Object Recognition test (NOR) has been investigated in mice. Moreover, to better characterize the effects of JWH-018-R compounds on memory function, in vitro electrophysiological and neurochemical studies in hippocampal preparations have been performed. JWH-018, JWH-018-Cl and JWH-018-Br dose-dependently impaired both short- and long-memory retention in mice (respectively 2 and 24 h after training session). Their effects resulted more potent respect to that evoked by Δ(9)-THC. Moreover, in vitro studies showed as JWH-018-R compounds negatively affected electrically evoked synaptic transmission, LTP and aminoacid (glutamate and GABA) release in hippocampal slices. Behavioral, electrophysiological and neurochemical effects were fully prevented by CB1 receptor antagonist AM251 pretreatment, suggesting a CB1 receptor involvement. These data support the hypothesis that synthetic JWH-018-R compounds, as Δ(9)-THC, impair cognitive function in mice by interfering with hippocampal synaptic transmission and memory mechanisms. This data outline the danger that the use and/or abuse of these synthetic cannabinoids may represent for the cognitive process in human consumer.

  18. Structural, Electronic, and Optical Properties of BiOX1−xYx (X, Y = F, Cl, Br, and I) Solid Solutions from DFT Calculations

    PubMed Central

    Zhao, Zong-Yan; Liu, Qing-Lu; Dai, Wen-Wu

    2016-01-01

    Six BiOX1−xYx (X, Y = F, Cl, Br, and I) solid solutions have been systematically investigated by density functional theory calculations. BiOCl1−xBrx, BiOBr1−xIx, and BiOCl1−xIx solid solutions have very small bowing parameters; as such, some of their properties increase almost linearly with increasing x. For BiOF1−xYx solid solutions, the bowing parameters are very large and it is extremely difficult to fit the related calculated data by a single equation. Consequently, BiOX1−xYx (X, Y = Cl, Br, and I) solid solutions are highly miscible, while BiOF1−xYx (Y = Cl, Br, and I) solid solutions are partially miscible. In other words, BiOF1−xYx solid solutions have miscibility gaps or high miscibility temperature, resulting in phase separation and F/Y inhomogeneity. Comparison and analysis of the calculated results and the related physical–chemical properties with different halogen compositions indicates that the parameters of BiOX1−xYx solid solutions are determined by the differences of the physical–chemical properties of the two halogen compositions. In this way, the large deviation of some BiOX1−xYx solid solutions from Vegard’s law observed in experiments can be explained. Moreover, the composition ratio of BiOX1−xYx solid solutions can be measured or monitored using optical measurements. PMID:27549344

  19. Structural, Electronic, and Optical Properties of BiOX1‑xYx (X, Y = F, Cl, Br, and I) Solid Solutions from DFT Calculations

    NASA Astrophysics Data System (ADS)

    Zhao, Zong-Yan; Liu, Qing-Lu; Dai, Wen-Wu

    2016-08-01

    Six BiOX1‑xYx (X, Y = F, Cl, Br, and I) solid solutions have been systematically investigated by density functional theory calculations. BiOCl1‑xBrx, BiOBr1‑xIx, and BiOCl1‑xIx solid solutions have very small bowing parameters; as such, some of their properties increase almost linearly with increasing x. For BiOF1‑xYx solid solutions, the bowing parameters are very large and it is extremely difficult to fit the related calculated data by a single equation. Consequently, BiOX1‑xYx (X, Y = Cl, Br, and I) solid solutions are highly miscible, while BiOF1‑xYx (Y = Cl, Br, and I) solid solutions are partially miscible. In other words, BiOF1‑xYx solid solutions have miscibility gaps or high miscibility temperature, resulting in phase separation and F/Y inhomogeneity. Comparison and analysis of the calculated results and the related physical–chemical properties with different halogen compositions indicates that the parameters of BiOX1‑xYx solid solutions are determined by the differences of the physical–chemical properties of the two halogen compositions. In this way, the large deviation of some BiOX1‑xYx solid solutions from Vegard’s law observed in experiments can be explained. Moreover, the composition ratio of BiOX1‑xYx solid solutions can be measured or monitored using optical measurements.

  20. Investigations of the Rg-BrCl (Rg=He, Ne, Ar, Kr, Xe) binary van der Waals complexes: ab initio intermolecular potential energy surfaces, vibrational states and predicted pure rotational transition frequencies.

    PubMed

    Li, Song; Zheng, Rui; Chen, Shan-Jun; Chen, Yan; Chen, Peng

    2017-03-05

    The intermolecular potential energy surfaces (PESs) of the ground electronic state for the Rg-BrCl (Rg=He, Ne, Ar, Kr, Xe) van der Waals complexes have been constructed by using the coupled-cluster method in combination with the augmented quadruple-zeta correlation-consistent basis sets supplemented with an additional set of bond functions. The features of the anisotropic PESs for these complexes are remarkably similar, which are characterized by three minima and two saddle points between them. The global minimum corresponds to a collinear Rg-Br-Cl configuration. Two local minima, correlate with an anti-linear Rg-Cl-Br geometry and a nearly T-shaped structure, can also be located on each PES. The quantum bound state calculations enable us to investigate intermolecular vibrational states and rotational energy levels of the complexes. The transition frequencies are predicted and are fitted to obtain their corresponding spectroscopic constants. In general, the periodic trends are observed for this complex family. Comparisons with available experimental data for the collinear isomer of Ar-BrCl demonstrate reliability of our theoretical predictions, and our results for the other two isomers of Ar-BrCl as well as for other members of the complex family are also anticipated to be trustable. Except for the collinear isomer of Ar-BrCl, the data presented in this paper would be beneficial to improve our knowledge for these experimentally unknown species.

  1. Investigations of the Rg-BrCl (Rg = He, Ne, Ar, Kr, Xe) binary van der Waals complexes: ab initio intermolecular potential energy surfaces, vibrational states and predicted pure rotational transition frequencies

    NASA Astrophysics Data System (ADS)

    Li, Song; Zheng, Rui; Chen, Shan-Jun; Chen, Yan; Chen, Peng

    2017-03-01

    The intermolecular potential energy surfaces (PESs) of the ground electronic state for the Rg-BrCl (Rg = He, Ne, Ar, Kr, Xe) van der Waals complexes have been constructed by using the coupled-cluster method in combination with the augmented quadruple-zeta correlation-consistent basis sets supplemented with an additional set of bond functions. The features of the anisotropic PESs for these complexes are remarkably similar, which are characterized by three minima and two saddle points between them. The global minimum corresponds to a collinear Rg-Br-Cl configuration. Two local minima, correlate with an anti-linear Rg-Cl-Br geometry and a nearly T-shaped structure, can also be located on each PES. The quantum bound state calculations enable us to investigate intermolecular vibrational states and rotational energy levels of the complexes. The transition frequencies are predicted and are fitted to obtain their corresponding spectroscopic constants. In general, the periodic trends are observed for this complex family. Comparisons with available experimental data for the collinear isomer of Ar-BrCl demonstrate reliability of our theoretical predictions, and our results for the other two isomers of Ar-BrCl as well as for other members of the complex family are also anticipated to be trustable. Except for the collinear isomer of Ar-BrCl, the data presented in this paper would be beneficial to improve our knowledge for these experimentally unknown species.

  2. Biological control of Cl/Br and low sulfate concentration in a 3.5-Gyr-old seawater from North Pole, Western Australia

    NASA Astrophysics Data System (ADS)

    Foriel, Julien; Philippot, Pascal; Rey, Patrice; Somogyi, Andrea; Banks, David; Ménez, Bénédicte

    2004-12-01

    The concentration of halogens (Cl, Br) and sulfate in seawater during the Archaean eon have important implications for the evolution of Earth's hydrosphere and atmosphere and the development of early life. Insights into the composition of Archaean seawater and hydrothermal fluids can be obtained by direct analysis of fluid inclusions preserved in Archaean sediments and hydrothermal systems. Here, we investigated a suite of well-preserved intrapillow quartz-carbonate pods that formed during oceanic hydrothermal alteration of the 3.49 Ga Dresser Formation, North Pole Dome, Western Australia. Texturally, the pods seems to contain a unique population of primary fluid inclusions which were analyzed individually using microthermometry and synchrotron radiation X-ray microfluorescence (μ-SR-XRF) techniques. Bulk chemical analyses were also performed using crush-leach method. Microthermometric data combined with crush-leach and μ-SR-XRF analyses yielded a model composition of 1100 mM Na, 2250 mM Cl., and 375 mM Ca, which corresponds to a bulk fluid salinity of 12 wt.% salt equivalent. This high Cl concentration (ca. four-times present-day value) reflects a typical modern-day seawater evaporation trend in a shallow marine, closed basin environment. Individual fluid inclusion analysis using μ-SR-XRF revealed the presence of three main fluid populations: a metal-depleted fluid, a Ba-rich and S-depleted fluid, and a Fe-S-rich end-member. The Cl/Br ratio of metal-depleted fluid inclusions (630) is similar to the modern seawater value (649). By contrast, Ba- and Fe-rich brines have Cl/Br ratios (350 and 390) close to bulk Earth value (420), hence arguing for a mantle buffering and a hydrothermal origin of these fluids. The metal-depleted fluid displays low sulfate concentration (0-8 mM compared to 28 mM in present-day ocean). Sulfur content of the Fe-rich fluids ranges between 41 and 82 mM. Fluid-rock interaction processes occurring in pillow basalts located on the seafloor

  3. Self-assembly of [UO2X4]2- (X=Cl, Br) dianions with γ substituted pyridinium cations: Structural systematics and fluorescence properties

    NASA Astrophysics Data System (ADS)

    Surbella, Robert G.; Andrews, Michael B.; Cahill, Christopher L.

    2016-04-01

    Room temperature self-assembly of [UO2X4]2- (X=Cl, Br) with γ substituted pyridinium cations has resulted in the formation of twelve compounds that were studied via single crystal X-ray diffraction and fluorescence spectroscopy. Systematic variation of electron donating groups on the pyridinium species is shown to influence the presence and/or strength of various supramolecular synthons, including hydrogen bonding and pi interactions. Combinations of such non-covalent interactions (NCIs) have given rise to a range of supramolecular assemblies, and are shown to influence uranyl emission by way of second sphere coordination to equatorial ligands.

  4. NMR shielding and spin–rotation constants of {sup 175}LuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br, {sup 127}I) molecules

    SciTech Connect

    Demissie, Taye B.

    2015-12-31

    This presentation demonstrates the relativistic effects on the spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants and shielding spans of {sup 175}LuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br, {sup 127}I) molecules. The results are obtained from calculations performed using density functional theory (non-relativistic and four-component relativistic) and coupled-cluster calculations. The spin-rotation constants are compared with available experimental values. In most of the molecules studied, relativistic effects make an order of magnitude difference on the NMR absolute shielding constants.

  5. Electronic structure, optical properties and bonding in alkaline earth halo-fluoride scintillators: BaClF, BaBrF and BaIF

    SciTech Connect

    Yedukondalu, N.; Babu, K. Ramesh; Bheemalingam, Ch.; Singh, David J; Vaitheeswaran, G.; Kanchana, V.

    2011-01-01

    We report first-principles studies of the structural, electronic, and optical properties of the alkaline-earth halofluorides, BaXF (X = Cl, Br, and I), including pressure dependence of structural properties. The band structures show clear separation of the halogen p derived valence bands into higher binding energy F and lower binding energy X derived manifolds reflecting the very high electronegativity of F relative to the other halogens. Implications of this for bonding and other properties are discussed. We find an anisotropic behavior of the structural parameters especially of BaIF under pressure. The optical properties on the other hand are almost isotropic, in spite of the anisotropic crystal structures.

  6. Parity violation in nuclear magnetic resonance frequencies of chiral tetrahedral tungsten complexes NWXYZ (X, Y, Z = H, F, Cl, Br or I)

    SciTech Connect

    Nahrwold, Sophie Berger, Robert; Schwerdtfeger, Peter

    2014-01-14

    Density functional theory within the two-component quasi-relativistic zeroth-order regular approximation (ZORA) is used to predict parity violation shifts in {sup 183}W nuclear magnetic resonance shielding tensors of chiral, tetrahedrally bonded tungsten complexes of the form NWXYZ (X, Y, Z = H, F, Cl, Br or I), as well as for the heavier systems NWHAtF and NWH(117)F for comparison. The calculations reveal that sub-mHz accuracy is required to detect such tiny effects in this class of compounds, and that parity violation effects are very sensitive to the choice of ligands.

  7. Extremely NA and CL Rich Chondrule AL3509 from the Allende Meteorite

    SciTech Connect

    Wasserburg, G J; Hutcheon, I D; Aleon, J; Ramon, E C; Krot, A N; Nagashima, K; Brearley, A J

    2011-04-07

    We report on the mineralogy, petrology, chemistry, oxygen isotopes, {sup 26}Al-{sup 26}Mg and {sup 36}Cl-{sup 36}S isotope systematics of the Allende chondrule Al3509 discovered and described by [1] and [2]. This spherical object ({approx}1cm {phi}) contains {approx}10% Na and 1% Cl, and nearly pure {sup 129}Xe [({sup 129}Xe/{sup 127}I) = 1.1 x 10{sup -4} (3)]. This high enrichment in halogens makes it of interest in searching for radiogenic {sup 36}S from {sup 36}Cl (t{sub 1/2} {approx} 0.3 Ma) decay. While there is strong evidence for the presence of {sup 36}Cl in sodalite and wadalite in CV CAIs [4,5], some sodalites show no evidence for excesses of {sup 36}S ({sup 36}S*). In contrast, high inferred initial {sup 36}Cl/{sup 35}Cl = 2 x 10{sup -5} has been found in wadalite from the Allende CAI AJEF [5]. The observed {sup 36}S excesses in sodalite are not correlated with radiogenic {sup 26}Mg, decay product of {sup 26}Al (t{sub 1/2} {approx} 0.72 Ma) [4]. From the inferred initial {sup 36}Cl/{sup 35}Cl ratios and consideration of both AGB and SNe stellar sources, {sup 36}Cl must be the product of charged particle irradiation within the early solar system. However, neither the specific nuclear production mechanism nor the irradiation site have been identified. Both sodalite and wadalite are found as late stage alteration products of CAIs together with grossular, monticellite, Al-rich pyroxene, wollastonite, nepheline, ferroan olivine, and ferroan pyroxenes. This late-stage alteration has been found to extensively change some CAIs in Allende, but clear residues of spinel, hibonite and Wark-Lovering rims are recognizable remnants of the original CAIs. The nature of the widespread volatile alteration process as well as that of the fluid phase remain controversial.

  8. Calcium-Ca/AlCl4/2-thionyl chloride cell - Performance and safety

    NASA Astrophysics Data System (ADS)

    Meitav, A.; Peled, E.

    1982-03-01

    Tests to determine the effect of concentration and temperature on the conductivity of Ca(AlCl4)2-thionyl chloride solutions, to assess the discharge performance of the Ca/Ca(AlCl4)2-thionyl chloride cell at varying temperatures and electrolyte concentrations, and to study the safety of the cell during charging and reversal in comparison to a LiAlCl4 electrolyte-based cell are reported. Flat cells were examined for discharge and cylindrical cells with a reference electrode were used for electrodeposition experiments. Conductivity was found to increase when temperature decreased in the Ca(AlCl4)2 solutions, with a preferred concentration set at 0.7 M for low temperatures and 1.25 M in the range 10-60 C. No anodic disintegration was observed with lithium cathodes, although an explosion hazard remained. Finally, sandwich-like Ca/Ca(AlCl4)2-thionyl chloride cells possessed the energy density of the Li-SO2 cells, and were also impossible to charge or overdischarge, indicating a suitability for high rate multicell battery applications.

  9. Velocity map imaging study of BrCl photodissociation at 467 nm: determination of all odd-rank (K = 1 and 3) anisotropy parameters for the Cl(2P(3/2)0) photofragments.

    PubMed

    Smolin, Andrey G; Vasyutinskii, Oleg S; Vieuxmaire, Olivier P J; Ashfold, Michael N R; Balint-Kurti, Gabriel G; Orr-Ewing, Andrew J

    2006-03-07

    Resonance-enhanced multiphoton ionization and velocity map imaging of the Cl(2P(3/2)0) fragments of BrCl photolysis at 467.16 nm have been used to obtain a complete set of orientation parameters (with ranks K = 1 and 3) describing the polarization of the electronic angular momentum. The experiments employ two geometries distinguished only by the circular or linear polarization of the photolysis laser beam. Normalized difference images constructed from the data accumulated using a right or left circularly polarized probe-laser beam, counterpropagating with the photolysis laser, were fitted to basis images corresponding to contributions from various odd-rank anisotropy parameters. Expressions are given for the difference images in terms of the K = 1 and 3 anisotropy parameters, which describe coherent and incoherent parallel and perpendicular excitation and dissociation mechanisms. The nonzero values of the anisotropy parameters are indicative of nonadiabatic dissociation dynamics, with likely contributions from flux on the A 3Pi1,B 3Pi(0+),C 1Pi1, and X 1sigma+(0+) states as well as one further omega = 1 state, all of which correlate adiabatically to Cl(2P(3/2)0) + Br(2P(3/2)0) photofragments. The magnitudes of the parameters depend both on the amplitudes of dissociative flux in these states, and also on the phases accumulated by the nuclear wave functions for different dissociation pathways.

  10. Facile formation of Ag{sub 2}WO{sub 4}/AgX (X = Cl, Br, I) hybrid nanorods with enhanced visible-light-driven photoelectrochemical properties

    SciTech Connect

    Li, Jingjing; Yu, Caiyun; Zheng, Changcheng; Etogo, Atangana; Xie, Yunlong; Zhong, Yijun; Hu, Yong

    2015-01-15

    Highlights: • Ag{sub 2}WO{sub 4}/AgX hybrid nanorods were prepared by a facile in-situ anion exchange reaction. • Ag{sub 2}WO{sub 4} nanorods and different X{sup −} ions were reacted in water at room temperature. • The hybrids possess significantly enhanced photoelectrochemical properties. • Ag{sub 2}WO{sub 4}/AgBr hybrids exhibit the highest photocatalytic activity among three samples. • The active species tests were also investigated to confirm photocatalytic mechanism. - Abstract: In this work, we demonstrated a general strategy for the preparation of a series of uniform Ag{sub 2}WO{sub 4}/AgX (X = Cl, Br, I) hybrid nanorods by a facile in-situ anion exchange reaction occurring at room temperature between pregrown Ag{sub 2}WO{sub 4} nanorods and different X{sup −} ions in water. Compared with Ag{sub 2}WO{sub 4} nanorods, further investigation has revealed that the as-prepared hybrid nanorods possess significantly enhanced photocurrent response and photocatalytic activity in degrading methyl orange (MO) under visible-light irradiation. In particular, the Ag{sub 2}WO{sub 4}/AgBr hybrid nanorods exhibit the highest photocatalytic activity among the three kinds of samples. The active species tests indicate that superoxide anion radicals and photogenerated holes are responsible for the enhanced photocatalytic performance.

  11. Inductively coupled BCl3/Cl2 /Ar plasma etching of Al-rich AlGaN

    DOE PAGES

    Douglas, Erica A.; Sanchez, Carlos A.; Kaplar, Robert J.; ...

    2016-12-01

    Varying atomic ratios in compound semiconductors is well known to have large effects on the etching properties of the material. The use of thin device barrier layers, down to 25 nm, adds to the fabrication complexity by requiring precise control over etch rates and surface morphology. The effects of bias power and gas ratio of BCl3 to Cl2 for inductively coupled plasma etching of high Al content AlGaN were contrasted with AlN in this study for etch rate, selectivity, and surface morphology. Etch rates were greatly affected by both bias power and gas chemistry. Here we detail the effects ofmore » small variations in Al composition for AlGaN and show substantial changes in etch rate with regards to bias power as compared to AlN.« less

  12. Antiperovskite Chalco-Halides Ba3(FeS4)Cl, Ba3(FeS4)Br, and Ba3(FeSe4)Br with Spin Super-Super Exchange

    PubMed Central

    Zhang, Xian; Liu, Kai; He, Jian-Qiao; Wu, Hui; Huang, Qing-Zhen; Lin, Jian-Hua; Lu, Zhong-Yi; Huang, Fu-Qiang

    2015-01-01

    Perovskite-related materials have received increasing attention for their broad applications in photovoltaic solar cells and information technology due to their unique electrical and magnetic properties. Here we report three new antiperovskite chalco-halides: Ba3(FeS4)Cl, Ba3(FeS4)Br, and Ba3(FeSe4)Br. All of them were found to be good solar light absorbers. Remarkably, although the shortest Fe-Fe distance exceeds 6 Å, an unexpected anti-ferromagnetic phase transition near 100 K was observed in their magnetic susceptibility measurement. The corresponding complex magnetic structures were resolved by neutron diffraction experiments as well as investigated by first-principles electronic structure calculations. The spin-spin coupling between two neighboring Fe atoms along the b axis, which is realized by the Fe-S···S-Fe super-super exchange mechanism, was found to be responsible for this magnetic phase transition. PMID:26525136

  13. Distance dependence of nonadiabaticity in the branching between C-Br and C-Cl bond fission following 1[n(O),π*(C=O)] excitation in bromopropionyl chloride

    NASA Astrophysics Data System (ADS)

    Kash, P. W.; Waschewsky, G. C. G.; Butler, L. J.; Francl, M. M.

    1993-09-01

    These experiments on bromopropionyl chloride investigate a system in which the barrier to C-Br fission on the lowest 1A` potential energy surface is formed from a weakly avoided electronic configuration crossing, so that nonadiabatic recrossing of the barrier to C-Br fission dramatically reduces the branching to C-Br fission. The results, when compared with earlier branching ratio measurements on bromoacetyl chloride, show that the additional intervening CH2 spacer in bromopropionyl chloride reduces the splitting between the adiabatic potential energy surfaces at the barrier to C-Br fission, further suppressing C-Br fission by over an order of magnitude. The experiment measures the photofragment velocity and angular distributions from the 248 nm photodissociation of Br(CH2)2COCl, determining the branching ratio between the competing primary C-Br and C-Cl fission pathways and detecting a minor C-C bond fission pathway. While the primary C-Cl:C-Br fission branching ratio is 1:2, the distribution of relative kinetic energies imparted to the C-Br fission fragments show that essentially no C-Br fission results from promoting the molecule to the lowest 1A` potential energy surface via the 1[n(O),π*(C=O)] transition; C-Br fission only results from an overlapping electronic transition. The results differ markedly from the predictions of statistical transition state theories which rely on the Born-Oppenheimer approximation. While such models predict that, given comparable preexponential factors, the reaction pathway with the lowest energetic barrier on the 1A` surface, C-Br fission, should dominate, the experimental measurements show C-Cl bond fission dominates by a ratio of C-Cl:C-Br=1.0:<0.05 upon excitation of the 1[n(O),π*(C=O)] transition. We compare this result to earlier work on bromoacetyl chloride, which evidences a less dramatic reduction in the C-Br fission pathway (C-Cl:C-Br=1.0:0.4) upon excitation of the same transition. We discuss a model in which

  14. Diurnal variation of BrO, HO2, HOCl, ClO, and O3 in the range from stratosphere to lower ionosphere observed by SMILES

    NASA Astrophysics Data System (ADS)

    Kasai, Yasuko; Sagawa, Hideo; Kuribayashi, Kouta

    A good understanding of halogen and hydrogen chemistry is required to understand Earth’s upper atmosphere above stratosphere. The abundance of these highly reactive species varies widely (within the parts per billion to parts per trillion range) on a day-to-day timescale due to photochemical reactions induced by sunlight. Until now, however, it has been difficult to accurately estimate their abundances and behavior. The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) is an atmospheric observation instrument with unprecedented sensitivity to monitor atmospheric minor compositions. SMILES is the first global environment observation instrument in the Japanese Experiment Module onboard the International Space Station (ISS). This mission is a joint project of the National Institute of Information and Communications Technology (NICT) and the Japan Aerospace Exploration Agency. The observation frequency bands of SMILES range from 624.32-626.32GHz to 649.12-650.32GHz. This range allows us to obtain vertical profiles of several atmospheric constituents simultaneously. We measure the abundance of O3 and its isotopic compositions, and of hydrochloric acid (HCl), ClO, HOCl, HO2, hydrogen peroxide (H2O2), BrO, acetonitrile (CH3CN), nitric acid (HNO3), water vapor, and ice clouds. The non-sun-synchronized orbit of the ISS gives us the opportunity to observe the diurnal variation of the species we measure. We performed atmospheric limb observations between 12 October 2009 and 21 April 2010. With the successful observations, we found that the amplitude of diurnal variations for halogen and hydrogen radicals (i.e., ClO, HOCl, HO2, and BrO) are quite large. Within one day, the abundance of BrO in the stratosphere and mesosphere varies from 0 to 16 parts per trillion. This comprises more than 80% of the total stratospheric bromine inventory. The results from SMILES represent the first studies of atmospheric composition diurnal variation using short-lived radical

  15. A study of the atmospherically important reactions between dimethyl selenide (DMSe) and molecular halogens (X2 = Cl2, Br2, and I2) with ab initio calculations.

    PubMed

    Rhyman, Lydia; Armata, Nerina; Ramasami, Ponnadurai; Dyke, John M

    2012-06-14

    The atmospherically relevant reactions between dimethyl selenide (DMSe) and the molecular halogens (X(2) = Cl(2), Br(2), and I(2)) have been studied with ab initio calculations at the MP2/aug-cc-pVDZ level of theory. Geometry optimization calculations showed that the reactions proceed from the reagents to the products (CH(3)SeCH(2)X + HX) via three minima, a van der Waals adduct (DMSe:X(2)), a covalently bound intermediate (DMSeX(2)), and a product-like complex (CH(3)SeCH(2)X:HX). The computed potential energy surfaces are used to predict what molecular species are likely to be observed in spectroscopic experiments such as gas-phase photoelectron spectroscopy and infrared matrix isolation spectroscopy. It is concluded that, for the reactions of DMSe with Cl(2) and Br(2), the covalent intermediate should be seen in spectroscopic experiments, whereas, in the DMSe + I(2) reaction, the van der Waals adduct DMSe:I(2) should be observed. Comparison is made with previous related calculations and experiments on dimethyl sulfide (DMS) with molecular halogens. The relevance of the results to atmospheric chemistry is discussed. The DMSeX(2) and DMSe:X(2) intermediates are likely to be reservoirs of molecular halogens in the atmosphere which will lead on photolysis to ozone depletion.

  16. Quantum mechanical modeling for the GeX(2)/GeHX + GeH(4) reactions (X = H, F, Cl, and Br).

    PubMed

    Bundhun, Ashwini; Blowers, Paul; Ramasami, Ponnadurai; Schaefer, Henry F

    2010-04-01

    A systematic theoretical investigation was carried out to study the reactions of various germylenes with germane. Molecular structures of the reactants (GeX(2) and GeHX, where X = H, F, Cl and Br) plus GeH(4), transition states, and products have been optimized to understand the effects of halo-substituted germylenes. The basis set used is of double-zeta plus polarization quality with additional s- and p-type diffuse functions. Consistent with experiment, the theoretical gas-phase reaction GeH(2) + GeH(4) --> Ge(2)H(6) possesses a negative activation energy. The predicted activation energies reveal interesting trends for both mono- and di- halo-substituted germylenes, -1.5 [GeH(2)], +20.5 [GeHF], +59.9 [GeF(2)], +18.0 [GeHCl], +46.8 [GeCl(2)], +17.3 [GeHBr], and +42.9 kcal mol(-1) [GeBr(2)]. There is a noteworthy relationship between the activation energies and the singlet-triplet splittings of the divalent germylenes. We report for the first time rate constants for the transfer of hydrogen, evaluated using standard transition-state theory with tunneling corrections. These results are analyzed and compared to the available experimental and previous theoretical findings for the gas-phase reactions involving germylene derivatives and germanium analogues.

  17. High-pressure single crystal X-ray diffraction study of the linear metal chain compound Co3(dpa)4Br2·CH2Cl2.

    PubMed

    Madsen, S R; Overgaard, J; Stalke, D; Iversen, B B

    2015-05-21

    The crystal structure of the linear metal chain compound Co3(dpa)4Br2·CH2Cl2 (1) has been investigated up to a pressure of 13.6(2) GPa in a diamond anvil cell (DAC) using single crystal X-ray diffraction. The structure remains orthorhombic as the unit cell volume is reduced by 30% at 12.8 GPa. At 13.6(2) GPa the diffraction pattern is of very poor quality and not even reliable unit cell parameters can be determined. Peak broadening resulting from non-hydrostatic conditions was avoided by annealing the loaded DAC prior to data collection, allowing reliable structural models to be refined up to a pressure of 11.8(2) GPa. On increasing pressure, the disordered CH2Cl2 crystal solvent molecule gradually becomes redistributed from one site to another. Hirshfeld surface analysis suggests that the redistribution is a result of repulsive HH interactions. Pressure also affects the molecular geometry, in particular the Co-Co and Co-Br bond lengths which decrease by 4% and 12%, respectively, at 11.8(2) GPa.

  18. Strongly visible-light responsive plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles for reduction of CO2 to methanol.

    PubMed

    An, Changhua; Wang, Jizhuang; Jiang, Wen; Zhang, Meiyu; Ming, Xijuan; Wang, Shutao; Zhang, Qinhui

    2012-09-21

    Plasmonic shaped AgX:Ag (X = Cl, Br) nanoparticles have been synthesized by a facile and versatile glycerol-mediated solution route. The as-prepared AgX:Ag nanoparticles exhibit regular shapes, i.e., cube-tetrapod-like AgCl:Ag nanoparticles and AgBr:Ag nanoplates. Compared with the pristine AgX, AgX:Ag nanocomposites display stronger absorption in the visible region due to the surface plasmon resonance of silver nanoparticles. The calculation of bandgaps and band positions indicates the as-achieved AgX:Ag nanoparticles can be used as a class of potential photocatalyst for the reduction of CO(2). For example, reduction of CO(2) under visible light irradiation with the assistance of the anisotropic AgX:Ag nanoparticles yields as much as 100 μmol methanol in the products. Furthermore, the AgX:Ag nanoparticles can maintain its structure and activity after 3 runs of reactions. Therefore, the present route opens an avenue to acquire plasmonic photocatalysts for conversion of CO(2) into useful organic compounds.

  19. Relevance of weak intermolecular forces on the supramolecular structure of free or DMSO solvated 5-(4-X-benzylidene)rhodanines (X = F, Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Casas, José S.; Castaño, M. Victoria; Couce, María D.; Sánchez, Agustín; Sordo, José; Torres, M. Dolores; Vázquez, Saulo A.; Vázquez-López, Ezequiel M.

    2016-09-01

    The rhodanines of the title (Xp-Rhod, X = F, Cl, Br, I) were synthesized and characterized in solid state and in solution. The crystal structures of the four compounds show different supramolecular organizations. In the F-, Cl- and Br-derivatives, a R22(8) (CSNH)2 ring forms via Nsbnd H⋯S hydrogen bonds between two neighbouring molecules to give dimers. The I-derivative is also dimeric, but exhibits R22(8) (CONH)2 rings. The two type of dimers are associated in a variety of structures through hydrogen bonding, π-stacking, Csbnd H⋯π interactions and halogen bonding. These interactions were analysed from a crystallographic point of view and their relative relevance was explored using DFT calculations. The effect produced on all these interactions by the incorporation of DMSO molecules to the lattice was analysed by comparing the crystal structures of Xp-Rhod compounds and those of corresponding Xp-RhodṡDMSO solvates.

  20. Diurnal variation climatology of short-lived at atmospheric compositions (ClO, BrO, HO2 and HOCl) derived from SMILES NICT data

    NASA Astrophysics Data System (ADS)

    Kreyling, Daniel; Sagawa, Hideo; Kasai, Yasuko

    2013-04-01

    We present a diurnal variation climatology for short-lived at atmospheric compositions, such as ClO, BrO, HO2 and HOCl, as well as for longer life time species, like O3 and HCl from observations of unprecedented sensitivity with the Superconducting SubMIllimeter wave Limb-Emission Sounder (SMILES), which is installed on the Japanese Experiment Module (JEM) at the International Space Station (ISS). With its non sun synchronous orbit, SMILES measurements comprise observations at all local times. The target altitude range is between lower stratosphere and mesopause. Differences in diurnal variation chemistry of strato-, and mesospheric BrO and ClO of the diurnal climatology are presented. The data employed is produced by the SMILES level 2 retrieval algorithm version 2.1.5 at the National Institute of Information and Communications Technology (NICT). The SMILES climatology data sets are available via the SMILES data distribution homepage in NICT at https://smiles-p6.nict.go.jp/products/research_latitude-longitude.jsf

  1. New approach to the fast screening of plant oil samples for F-, Cl-, Br- and S-organic compounds on the trace level.

    PubMed

    Chivarzin, M E; Revelsky, I A; Nikoshina, A V; Buldyzkova, A N; Chepeliansky, D A; Revelsky, A I; Buriak, A K

    2016-04-01

    The fast method of the simultaneous determination of F(-), Cl(-), Br(-) and SO4(2-) anions in the deionized water on the trace level by ion chromatography using thorough cleaning of respective water containers, 10 μM NaHCO3 water solution as eluent, short Metrohm (50 × 4 mm) separation column and a large water volume injection is proposed. Calculated detection limits are 10(-9)-10(-8)% depending on the element. The method for the fast screening of plant oil samples for the total fluorine-, chlorine-, bromine- and sulfur-organic compounds content (calculated for the respective elements) on the trace level is developed. It is based on the high temperature combustion of oil sample in oxygen flow, absorption of the conversion products in deionized water and whole absorbate volume analysis for F(-), Cl(-), Br(-) and SO4(2-) anions, corresponding to the respective elements, using the developed method of these anions analysis by ion chromatography. The samples of soya, olive, sunflower and cotton seed oil were analyzed. The method detection limits (for 1mg sample) were 2 × 10(-6)%, 2 × 10(-6)%, 5 × 10(-6)% and 5 × 10(-6)% for fluorine, chlorine, bromine and sulfur, respectively. The relative standard deviation was ≤ 15%. The method gives the compressed information about the total content of all target and nontarget fluorine-, chlorine-, bromine- and sulfur-organic compounds in plant oils.

  2. Fenugreek seeds, a hepatoprotector forage crop against chronic AlCl3 toxicity

    PubMed Central

    2013-01-01

    Background Having considered how bioavailable aluminium (Al) may affect ecological systems and animals living there, especially cattle, and in search for a preventive dietary treatment against Al toxicity, we aimed to test the protective role of fenugreek seeds against chronic liver injury induced by aluminum chloride (AlCl3) in Wistar rats. Results Five months of AlCl3 oral exposure (500 mg/kg bw i.g for one month then 1600 ppm via drinking water) caused liver atrophy, an inhibition of aspartate transaminase (AST), alanine transaminase (ALT) and glutamyl transpeptidase (GGT), an enhancement of both lipid peroxidation and lactate dehydrogenase (LDH) activity and an increase of total protein level in liver. Moreover, histopathological and histochemical examinations revealed moderate alterations in the hepatic parenchyma in addition to a disrupted iron metabolism. Co-administration of fenugreek seed powder (FSP) at 5% in pellet diet during two months succeeded to antagonize the harmful effects of AlCl3 by restoring all tested parameters. Conclusion This study highlighted the hepatotoxicity of AlCl3 through biochemical and histological parameters in one hand and the hepatoprotective role of fenugreek seeds on the other hand. Thus this work could be a pilot study which will encourage farmers to use fenugreek seeds as a detoxifying diet supplement for domestic animals. PMID:23363543

  3. Energy level analysis of Np3+:LaCl3 and Np3+:LaBr3

    NASA Astrophysics Data System (ADS)

    Carnall, W. T.; Crosswhite, H.; Crosswhite, H. M.; Hessler, Jan P.; Edelstein, N.; Conway, J. G.; Shalimoff, G. V.; Sarup, R.

    1980-05-01

    The polarized absorption and fluorescence spectra of 0.01-5% Np3+ doped into single-crystal LaCl3 were measured at moderate and high resolution in the range to 50 000 cm-1 at 298, 77, and 4 K. The 150 crystal field components identified were fit by a parametrized model which has previously been shown to provide an excellent account of the energy level structures observed for lanthanides doped into LaCl3. This constitutes the first successful evaluation of the crystal field interaction for an actinide ion in LaCl3 in which J mixing effects were explicitly included. The crystal field parameters for Np3+:LaCl3, B20=163, B40=-632, B60=-1625, and B66=1028, all in cm-1, were determined to be approximately twice as large as those for the analogous lanthanide, Pm3+:LaCl3. From analysis of Zeeman patterns in the fluorescence spectra, the ground state was found to be doubly degenerate, having crystal quantum numbers ±2 and a parallel splitting factor 0.17 LU (Lorentz unit).

  4. Nearly Monodisperse Insulator Cs4PbX6 (X = Cl, Br, I) Nanocrystals, Their Mixed Halide Compositions, and Their Transformation into CsPbX3 Nanocrystals.

    PubMed

    Akkerman, Quinten A; Park, Sungwook; Radicchi, Eros; Nunzi, Francesca; Mosconi, Edoardo; De Angelis, Filippo; Brescia, Rosaria; Rastogi, Prachi; Prato, Mirko; Manna, Liberato

    2017-03-08

    We have developed a colloidal synthesis of nearly monodisperse nanocrystals of pure Cs4PbX6 (X = Cl, Br, I) and their mixed halide compositions with sizes ranging from 9 to 37 nm. The optical absorption spectra of these nanocrystals display a sharp, high energy peak due to transitions between states localized in individual PbX6(4-) octahedra. These spectral features are insensitive to the size of the particles and in agreement with the features of the corresponding bulk materials. Samples with mixed halide composition exhibit absorption bands that are intermediate in spectral position between those of the pure halide compounds. Furthermore, the absorption bands of intermediate compositions broaden due to the different possible combinations of halide coordination around the Pb(2+) ions. Both observations are supportive of the fact that the [PbX6](4-) octahedra are electronically decoupled in these systems. Because of the large band gap of Cs4PbX6 (>3.2 eV), no excitonic emission in the visible range was observed. The Cs4PbBr6 nanocrystals can be converted into green fluorescent CsPbBr3 nanocrystals by their reaction with an excess of PbBr2 with preservation of size and size distributions. The insertion of PbX2 into Cs4PbX6 provides a means of accessing CsPbX3 nanocrystals in a wide variety of sizes, shapes, and compositions, an important aspect for the development of precisely tuned perovskite nanocrystal inks.

  5. Structure and stability of noble gas bound EX3+ compounds (E = C, Ge, Sn, Pb; X = H, F, Cl, Br).

    PubMed

    Pan, Sudip; Moreno, Diego; Ghosh, Sreyan; Chattaraj, Pratim K; Merino, Gabriel

    2016-01-15

    It has been analyzed at the MP2/def2-QZVPPD level whether EX3+ (E = C-Pb; X = H, F-Br) can bind noble gas atoms. Geometrical and electronic structures, dissociation energy values, thermochemical parameters, natural bond order, electron density, and energy decomposition analyses highlight the possibility of such noble gas bound EX3+ compounds. Except He and Ne, the other heavier congeners of this family make quite strong bonds with E. In fact, the dissociations of Ar-Rn bound analogues turn out to be endergonic in nature at 298 K, except in the cases of ArGe Cl3+, Ar/KrGeBr3+, and ArSnBr3+. GeH3+ and EF3+ (E = Ge-Pb) can even bind two Ng atoms with reasonably high dissociation energy. As the pz orbital of the E center in EX3+ plays a crucial role in its binding with the noble gas atoms, the effect of the π back-bonding causing X → E electron transfer ought to be properly understood. Due to the larger back-donation, the Ng binding ability of EX3+ gradually decreases along F to Br. EH2+ and the global minimum HE(+…) H2 (E = Sn, Pb) complexes are also able to bind Ar-Rn atoms quite effectively. The NgE bonds in Ar-Rn bound CH3+, GeH3+, and EF3+ (E = Ge-Pb) and Xe/RnE bonds in NgECl3+ and NgEBr3+ (E = Ge, Sn) are mainly of covalent type.

  6. Nearly Monodisperse Insulator Cs4PbX6 (X = Cl, Br, I) Nanocrystals, Their Mixed Halide Compositions, and Their Transformation into CsPbX3 Nanocrystals

    PubMed Central

    2017-01-01

    We have developed a colloidal synthesis of nearly monodisperse nanocrystals of pure Cs4PbX6 (X = Cl, Br, I) and their mixed halide compositions with sizes ranging from 9 to 37 nm. The optical absorption spectra of these nanocrystals display a sharp, high energy peak due to transitions between states localized in individual PbX64– octahedra. These spectral features are insensitive to the size of the particles and in agreement with the features of the corresponding bulk materials. Samples with mixed halide composition exhibit absorption bands that are intermediate in spectral position between those of the pure halide compounds. Furthermore, the absorption bands of intermediate compositions broaden due to the different possible combinations of halide coordination around the Pb2+ ions. Both observations are supportive of the fact that the [PbX6]4– octahedra are electronically decoupled in these systems. Because of the large band gap of Cs4PbX6 (>3.2 eV), no excitonic emission in the visible range was observed. The Cs4PbBr6 nanocrystals can be converted into green fluorescent CsPbBr3 nanocrystals by their reaction with an excess of PbBr2 with preservation of size and size distributions. The insertion of PbX2 into Cs4PbX6 provides a means of accessing CsPbX3 nanocrystals in a wide variety of sizes, shapes, and compositions, an important aspect for the development of precisely tuned perovskite nanocrystal inks. PMID:28196323

  7. Using Halogens (Cl, Br, F, I) and Stable Isotopes of Water (δ18O, δ2H) to Trace Hydrological and Biogeochemical Processes in Prairie Wetlands

    NASA Astrophysics Data System (ADS)

    Levy, Z. F.; Lu, Z.; Mills, C. T.; Goldhaber, M. B.; Rosenberry, D. O.; Mushet, D.; Siegel, D. I.; Fiorentino, A. J., II; Gade, M.; Spradlin, J.

    2014-12-01

    Prairie pothole wetlands are ubiquitous features of the Great Plains of North America, and important habitat for amphibians and migratory birds. The salinity of proximal wetlands varies highly due to groundwater-glacial till interactions, which influence wetland biota and associated ecosystem functions. Here we use halogens and stable isotopes of water to fingerprint hydrological and biogeochemical controls on salt cycling in a prairie wetland complex. We surveyed surface, well, and pore waters from a groundwater recharge wetland (T8) and more saline closed (P1) and open (P8) basin discharge wetlands in the Cottonwood Lake Study Area (ND) in August/October 2013 and May 2014. Halogen concentrations varied over a broad range throughout the study area (Cl = 2.2 to 170 mg/L, Br = 13 to 2000 μg/L, F = < 30 (MDL) to 740 μg/L, I = 1 to 538 μg/L). The Cl/Br molar ratios were higher (171 to 574) at the recharge wetland, indicating meteoric sources, and had a tighter and lower range (33 to 320) at the down-gradient sites. The Cl/I molar ratios of waters throughout the site had a wide range (32 to 26,000). Lowest values occurred at the upgradient shore of P1 (32 to 43) due to low Cl concentrations and the center of P1 (196 to 213) where pore water of weathered till underlying 1.2 m of organic-rich sediment and silty clay soil is enriched in I to ~500 µg/L. Stable isotopes of water showed that evaporation-enriched pond water (δ18O = -9.5 to -2.71 ‰) mixes with shallow groundwater in the top 0.6 m of fringing wetland soils and 1.2 m of the substrate in the center of P1. Our results suggest endogenous sources for Br and I within the prairie landscape that may be controlled by biological mechanisms or weathering of shale from glacial till.

  8. Ion-pairing in aqueous CaCl2 and RbBr solutions. Simultaneous structural refinement of XAFS and XRD data

    SciTech Connect

    Pham, Thai V.; Fulton, John L.

    2013-01-22

    We present a new methodology involving the simultaneous refinement of both x-ray absorption and x-ray diffraction spectra (X-ray Absorption/Diffraction Structural Refinement,XADSR), to study hydration and ion pair structure of CaCl2 and RbBr salts in concentrated aqueous solutions. The XADSR analysis includes the XAFS spectra analysis of both the cation and anion as a probe of their short-range structure with an XRD spectral analysis as a probe of the global structural. Together they deliver a comprehensive picture of the cation and anion hydration, the contact ion pair (CIP) structure and the solvent-separated ion pair (SSIP) structure. XADSR analysis of 6.0 m aqueous CaCl2 reveals that there are an insignificant number of Ca2+-Cl- CIP’s, but there are approximately 3.4 SSIP’s separated by about 4.99 Å. In contrast XADSR analysis of aqueous RbBr yields about 0.7 pair CIP at a bond length 3.51 Å. The present work demonstrates a new approach for a direct co-refinement of XRD and XAFS spectra in a simple and reliable fashion, opening new opportunities for analysis in various disordered and crystalline systems. This work was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is operated for the U.S. Department of Energy by Battelle.

  9. Br/Cl ratios and O, H, C, and B isotopic constraints on the origin of saline waters from eastern Canada

    NASA Astrophysics Data System (ADS)

    Leybourne, M. I.; Goodfellow, W. D.

    2007-05-01

    Saline groundwaters were recovered from undisturbed (Restigouche deposit) and active (Brunswick #12 mine) Zn-Pb volcanogenic massive sulfide deposits in the Bathurst Mining Camp (BMC), northern New Brunswick, Canada. These groundwaters, along with fresh to brackish meteoric ground and surface waters from the BMC, have been analyzed to determine their major, trace element and stable isotopic (O, H, C, and B) compositions. Saline groundwaters (total dissolved solids = 22-45 g/L) are characterized by relatively high Na/Ca ratios compared to brines from the Canadian Shield and low Na/Cl molar and δ11B isotopic compositions (-2.5‰ to 11.1‰) compared to seawater. Although saline waters from the Canadian Shield commonly have oxygen and hydrogen isotopic compositions that plot to the left of the global meteoric water line, those from the BMC fall close to the water line. Fracture and vein carbonate minerals at the Restigouche deposit have restricted carbon isotopic compositions of around -5‰ to -6‰. The carbon isotopic compositions of the saline waters at the Restigouche deposit (+12‰ δ13C DIC) are the result of fractionation of dissolved inorganic carbon by methanogenesis. We suggest that, unlike previous models for shield brines, the composition of saline waters in the BMC is best explained by prolonged water-rock reaction, with no requirement of precursor seawater. We suggest that elevated Br/Cl ratios of saline waters compared to seawater may be explained by differential uptake of Br and Cl during groundwater evolution through water-rock reaction.

  10. The 1988 Arctic Survey, Diurnal Study (Sunrise and Sunset) and Peak Altitude (22 km) Flights for the In Situ Detection of ClO and BrO from the NASA ER-2 Aircraft

    NASA Technical Reports Server (NTRS)

    Anderson, James G.

    1996-01-01

    Two critical areas of research were addressed successfully by this research. The first involves NASA ER-2 airborne observations of ClO and BrO radical destruction of ozone within the arctic vortex. The second involves the analysis of diurnal variations in ClO, to test the production and loss rates of ClO that constitutes the test for coupling reactions between the chlorine and nitrogen systems. We discuss results from this research in order.

  11. Partitioning of Excess Energy in the Photolysis of ClCN and BrCN at 193 NM.

    DTIC Science & Technology

    1982-04-08

    7c orbital, and thus concluded that the upper state was a linear III system. Rabelais , et al (12), in a study of the electronic structure of sixteen...thea continuum corresponds to a (OA’ or IA") * XlE + ) transition. If Rabelais , et al are correct in their conclusion that the excited state is bent

  12. Crystal structure, phase transition and conductivity study of two new organic - inorganic hybrids: [(CH2)7(NH3)2]X2, X = Cl/Br

    NASA Astrophysics Data System (ADS)

    Mostafa, Mohga Farid; El-khiyami, Shimaa Said; Abd-Elal, Seham Kamal

    2017-01-01

    Two hybrids 1,7-heptanediammonium di-halide, [(C7H20N2]X2,X = Cl/Br crystallize in monoclinic P21/c, Z = 4. [(C7H20N2]Cl2: a = 4.7838 (2) Å, b = 16.9879 (8) Å, c = 13.9476 (8) Å, β = 97.773 (2)°, V = 1203.58(10) Å3, D = 1.137 g/cm3, λ = 0.71073 Å, R = 0.052 for 1055 reflections with I > 2σ(I), T = 298(2) K. [(C7H20N2]Br2: a = 4.7952 (10) Å, b = 16.9740 (5) Å, c = 13.9281 (5) Å, β = 97.793 (2)°, V = 1203.83(6) Å3, D = 1.612 g/cm3, λ = 0.71073 Å, R = 0.03 for 1959 reflections with I > 2σ(I) T = 298(2) K. Asymmetric unit cell of [(C7H20N2]X2,X = Cl/Br, each consist of one heptane-1,7-diammonium cation and two halide anions. The organic hydrocarbon layers pack in a stacked herring-bone manner, hydrogen bonded to the halide ions. Lattice potential energy is 1568.59 kJ/mol and 1560.78 kJ/mol, and cation molar volumes are 0.295 nm3 and 0.300 nm3 for chloride and bromide respectively. DTA confirmed chain melting transitions for both hybrids below T ∼ 340 K. Dielectric and ac conductivity measurements (290 < T K < 410; 0.080 < f kHz<100) indicated higher conductivity and activation energy of bromide for T > 340 K. Cross over from Jonscher's universal dielectric response at low temperatures T < 340 K to super-linear power law for T > 340 K is observed. At high temperatures halide ion hopping in accordance with the jump relaxation model prevails.

  13. Behavior of Al2O3 and SiO2 with heating in a Cl2 + CO stream

    NASA Technical Reports Server (NTRS)

    Shchetinin, L. K.

    1984-01-01

    Differential thermal analysis (DTA) and Thermogravimetric analysis (TGA) were used to study the chlorination of alpha-Al2O3, gamma-Al2O3 and amorphous SiO2 in a Cl + CO stream, for the preparation of AlCl3 and SiCl4. The chlorination starting temperatures were 235 deg for Al2O3 and 680 deg for SiO2. The chlorination of alpha- and gamma-Al2O3 takes place via the formation of AlOCl as an intermediate product, and its subsequent dissociation at 480 to 560 deg, according to 3AlOCl yields AlCl3 + Al2O3. The chlorination activation energies are given for the three oxides.

  14. A four-component Fock-space coupled cluster investigation of the XMn(CO)5, (X = Cl, Br and I) photoelectron spectra

    NASA Astrophysics Data System (ADS)

    Nikoobakht, Behnam; Siebert, Max; Pernpointner, Markus

    2017-01-01

    In this work we readdress the theoretical interpretation of the XMn(CO)5, X = Cl, Br, I photoelectron spectra by applying four-component Fock-space coupled cluster methods for their calculation. The final state characterization was based on group theoretical considerations of the contributing metal and ligand orbitals and the applied electronic structure methods extend earlier studies based on less demanding approaches. Energy level diagrams show the effect of spin-orbit (SO) coupling starting from scalar-relativistic results and especially for the heavy representative IMn(CO)5 a sizeable influence of the iodine p spinors on the spectral features and nonadditivity effects of SO and electron correlation contributions could be observed.

  15. On the Versatility of BH2 X (X=F, Cl, Br, and I) Compounds as Halogen-, Hydrogen-, and Triel-Bond Donors: An Ab Initio Study.

    PubMed

    Bauzá, Antonio; Frontera, Antonio

    2016-10-18

    In this manuscript, the ability of BH2 X compounds (X=F, Cl, Br, and I) to establish halogen-, hydrogen-, and triel-bonding interactions was studied at the RI-MP2/aug-cc-pVQZ level of theory. Several homodimers were taken into account, highlighting the versatility of these compounds to act as both electron donors and electron acceptors. Natural bond orbital analysis showed that orbital effects were important contributors to the global stabilization of the σ- and π-hole bonded complexes studied. Finally, some X-ray solid-state structures retrieved from the Cambridge structural database were described to demonstrate the importance of these interactions involving boron derivatives in the solid state.

  16. Theoretical study of the gas-phase SN2 reactions of X- with CH3OY (X, Y = Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Gai, Jing-Gang; Ren, Yi

    The gas-phase nucleophilic substitution reactions at saturated oxygen X- + CH3OY (X, Y D Cl, Br, I) have been investigated at the level of CCSD(T)/6-311+G(2df,p)//B3LYP/6-311+G(2df,p). The calculated results indicate that X- preferably attacks oxygen atom of CH3OY via a SN2 pathway. The central barriers and overall barriers are respectively in good agreement with both the predictions of Marcus equation and its modification, respectively. Central barrier heights (?HXY? and ?HYX?) correlate well with the charges (Q) of the leaving groups (Y), Wiberg bond orders (BO) and the elongation of the bonds (O―Y and O―X) in the transition structures.

  17. A comparative study of AgX (X = Cl(-), Br(-), I(-) and N(3)(-)) solid-phase reactors for flow-injection determination of cyanide in electroplating wastewater.

    PubMed

    Noroozifar, Meissam; Khorasani-Motlagh, Mozhgan; Taheri, Aboozar; Zare-Dorabei, Rohollah

    2008-05-01

    In this study, a rapid flow injection-flame atomic absorption spectrometry for cyanide detection was developed. Different AgX (where X is Cl(-), Br(-), I(-) and N(3)(-)) solid-phase reagents (SPR) were tested for indirect determination of cyanide. In a single-line FIA system, the cyanide was allowed to react with AgX SPR, which in turn changed Ag ions in AgX to silver cyanide complexes in a sodium hydroxide carrier stream. The eluent containing the analyte as silver cyanide complexes was measured by FAAS. The calibration curve was linear up to 30 mg l(-1) with a detection limit of 0.05 mg l(-1) for cyanides. The sampling rate and the relative standard deviation were <1.09% and >200 h(-1), respectively. The method was applied to the determination of cyanide in electroplating wastewater.

  18. Strong magnetic-dielectric-lattice coupling in transition metal hydroxyhalides and ferroelectric response in rhombohedral Co2(OD)3X (X=Cl, Br)

    NASA Astrophysics Data System (ADS)

    Zheng, X. G.; Fujihala, M.; Kitajima, S.; Maki, M.; Kato, K.; Takata, M.; Xu, C. N.

    2013-05-01

    Hydroxyl salts of the type M2(OH)3X, and M(OH)X, where M represents a transition metal ion and X represents a halogen ion, widely exist as minerals and were recently reported to be geometrically frustrated magnets. Here, we report the finding of ferroelectric response in them. First, we observed strong magnetic-lattice-dielectric couplings in all of them as witnessed during their magnetic transitions at low temperatures. Secondly, we identified apparent ferroelectric responses in the deuterated hydroxyl salts of high crystal symmetries, i.e., rhombohedral Co2(OD)3Cl and Co2(OD)3Br, at high temperatures of 220-230 K through an isotope effect. The present work shows that multiferroicity may be a potentially universal phenomenon in magnetic hydroxyl salts. Meanwhile, it provides the first link between magnetic geometric frustration and hydrogen-bonded soft-mode ferroelectrics.

  19. Atomiclike ionization and fragmentation of a series of CH3-X (X: H, F, Cl, Br, I, and CN) by an intense femtosecond laser.

    PubMed

    Tanaka, Michinori; Murakami, Masanao; Yatsuhashi, Tomoyuki; Nakashima, Nobuaki

    2007-09-14

    Methane derivatives of CH(3)-X (X: H, F, Cl, Br, I, and CN) were ionized and fragmented by an intense femtosecond laser with a 40 fs pulse at 0.8 microm in intensities of 10(13)-10(15) W cm(-2). The curves of the ionization yields of CH(3)-X versus laser intensities have been found to be fitted with an atomic ionization theory (the theory of Perelomov, Popov, and Terent'ev) that has been established to reproduce experimental results well for rare gas atoms. The saturation intensities have been reproduced within a factor of 1.6 of the calculated ones. For molecules with low ionization potentials such as amines, another atomic ionization theory (the theory of Ammosov, Delone, and Krainov) reproduced the saturation intensities. The atomiclike ionization behavior of molecules indicates that the fragmentation occurs after the ionization. The fragmentation mechanisms after the ionization of some molecular ions are discussed.

  20. Atomiclike ionization and fragmentation of a series of CH3-X (X: H, F, Cl, Br, I, and CN) by an intense femtosecond laser

    NASA Astrophysics Data System (ADS)

    Tanaka, Michinori; Murakami, Masanao; Yatsuhashi, Tomoyuki; Nakashima, Nobuaki

    2007-09-01

    Methane derivatives of CH3-X (X: H, F, Cl, Br, I, and CN) were ionized and fragmented by an intense femtosecond laser with a 40fs pulse at 0.8μm in intensities of 1013-1015Wcm-2. The curves of the ionization yields of CH3-X versus laser intensities have been found to be fitted with an atomic ionization theory (the theory of Perelomov, Popov, and Terent'ev) that has been established to reproduce experimental results well for rare gas atoms. The saturation intensities have been reproduced within a factor of 1.6 of the calculated ones. For molecules with low ionization potentials such as amines, another atomic ionization theory (the theory of Ammosov, Delone, and Krainov) reproduced the saturation intensities. The atomiclike ionization behavior of molecules indicates that the fragmentation occurs after the ionization. The fragmentation mechanisms after the ionization of some molecular ions are discussed.

  1. Temperature-controlled syntheses of substituted 1,2,4-triazolelead(II) complexes: active lone pair and N-H...X (X = Cl, Br, I) hydrogen bonds.

    PubMed

    Cheng, Jian-Kai; Zhang, Jian; Yin, Pei-Xiu; Lin, Qi-Pu; Li, Zhao-Ji; Yao, Yuan-Gen

    2009-11-02

    Three isomorphous lead(II) complexes with a new {N(3)SX}-coordinated (X = Cl, Br, I) mode have been synthesized and characterized by X-ray diffraction. The structural analyses reveal that the coordination environment around the center metal is distinctly influenced by the stereochemical 6s(2) lone pair and N-H...X hydrogen bonds. Additionally, doubly deprotonated trzS(2-) (HtrzSH = 1,2,4-triazole-3-thiol) generated in situ via deamination and dehydrazination of ahtrzS(-) (ahtrzSH = 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole) was first observed in a semiconducting three-dimensional coordination network at higher reaction temperature.

  2. Two-dimensional rectangular tantalum carbide halides TaCX (X = Cl, Br, I): novel large-gap quantum spin Hall insulators

    NASA Astrophysics Data System (ADS)

    Zhou, Liujiang; Shi, Wujun; Sun, Yan; Shao, Bin; Felser, Claudia; Yan, Binghai; Frauenheim, Thomas

    2016-09-01

    Quantum spin Hall (QSH) insulates exist in special two-dimensional (2D) semiconductors, possessing the quantized spin-Hall conductance that are topologically protected from backscattering. Based on the first-principles calculations, we predict a novel family of QSH insulators in 2D tantalum carbide halides TaCX (X = Cl, Br, and I) with unique rectangular lattice and large direct energy gaps. The mechanism for 2D QSH effect originates from an intrinsic d-d band inversion in the process of chemical bonding. Further, stain and intrinsic electric field can be used to tune the electronic structure and enhance the energy gap. TaCX nanoribbon, which has the single-Dirac-cone edge states crossing the bulk band gap, exhibits a linear dispersion with a high Fermi velocity comparable to that of graphene. These 2D materials with considerable nontrivial gaps promise great application potential in the new generation of dissipationless electronics and spintronics.

  3. Tunable Length and Optical Properties of CsPbX3 (X = Cl, Br, I) Nanowires with a Few Unit Cells.

    PubMed

    Amgar, Daniel; Stern, Avigail; Rotem, Dvir; Porath, Danny; Etgar, Lioz

    2017-02-08

    Perovskite nanostructures, both hybrid organo-metal and fully inorganic perovskites, have gained a lot of interest in the past few years for their intriguing optical properties in the visible region. We report on inorganic cesium lead bromide (CsPbBr3) nanowires (NWs) having quantum confined dimensions corresponding to 5 unit cells. The addition of various hydrohalic acids (HX, X = Cl, Br, I) was found to highly affect the NW length, composition, and optical properties. Hydrochloric (HCl) and hydroiodic (HI) acids mixed in the reaction solution influence the crystal structure and optical properties and shorten the NWs, while the hydrobromic acid (HBr) addition results solely in shorter NWs, without any structural change. The addition of HX increases the acidity of the reaction solution, resulting in protonation of the oleylamine ligands from oleylamine into oleyl-ammonium cations that behave similarly to Cs(+) during crystallization. Therefore, the positions of the Cs(+) at the growing surface of the NWs are taken by the oleyl-ammonium cations, thus blocking further growth in the favored direction. The emission of the NWs is tunable between ∼423-505 nm and possesses a potential in the optoelectronic field. Moreover, electrical conductivity measurements of the NWs are discussed to give a new point of view regarding the conductivity of perovskite nanostructures.

  4. Theoretical calculations of spin-Hamiltonian parameters for the (MoOX5)2- (X=Cl, Br) metallic complexes in solution or frozen-glass

    NASA Astrophysics Data System (ADS)

    Mei, Yang; Zheng, Wen-Chen; Zhang, Lin; Chen, Bo-Wei

    2014-11-01

    The spin-Hamiltonian parameters (g factors g//, g⊥ and hyperfine structure constants A//, A⊥) of the (MoOX5)2- (X=Cl, Br) metallic complexes in solution or frozen-glass are calculated from the high-order perturbation formulas based on the two-mechanism model. In these formulas, the contributions to spin-Hamiltonian parameters due to both the widely-applied crystal-field (CF) mechanism and the charge-transfer (CT) mechanism (which is neglected in CF theory) are taken into account, and the needed CF and CT energy levels are obtained from the optical spectra. The calculated results with two adjustable parameters are in reasonable agreement with the experimental values. The calculations show that (i) the relative importance of CT mechanism in (MoOBr5)2- metallic complexes is larger than that in (MoOCl5)2- ones because of the stronger covalence of Mo5+-Br- combination, and (ii) in both (MoOCl5)2- and (MoOBr5)2- metallic complexes, the contributions to spin-Hamiltonian parameters due to CT mechanism should also be taken into account because of the high valence state of Mo5+ ion.

  5. SMILES zonal and diurnal variation climatology of stratospheric and mesospheric trace gasses: O3, HCl, HNO3, ClO, BrO, HOCl, HO2, and temperature

    NASA Astrophysics Data System (ADS)

    Kreyling, Daniel; Sagawa, Hideo; Wohltmann, Ingo; Lehmann, Ralph; Kasai, Yasuko

    2013-10-01

    We present a climatology of the diurnal variation of short-lived atmospheric compounds, such as ClO, BrO, HO2, and HOCl, as well as longer-lived species: O3, the hydrogen chloride isotopes H35Cl and H37Cl, and HNO3. Measurements were taken by the Superconducting Submillimeter-wave Limb-Emission Sounder (SMILES). This spectrally resolving radiometer, with very low observation noise and altitude range from the lower stratosphere to the lower thermosphere (20-100km), was measuring vertical profiles of absorption spectra along a non-sun-synchronous orbit, thus observing at all local times. We used the retrieved volume mixing ratio profiles to compile climatologies that are a function of pressure, a horizontal coordinate (latitude or equivalent latitude), and a temporal coordinate (solar zenith angle or local solar time). The main product presented are climatologies with a high resolution of the temporal coordinate (diurnal variation climatologies). In addition, we provide climatologies with a high resolution of the horizontal coordinate (zonal climatologies).The diurnal variation climatologies are based on data periods of 2 months and the zonal climatologies on monthly data periods. Consideration of the SMILES time-space sampling patterns with respect to the averaging coordinates is a key issue for climatology creation, especially in case of diurnal variation climatologies. Biases induced by inhomogeneous sampling are minimized by carefully choosing the size of averaging bins. The sampling biases of the diurnal variation climatology of ClO and BrO are investigated in a comparison of homogeneously sampled model data versus SMILES-sampled model data from the stratospheric Lagrangian chemistry and transport model Alfred Wegener Institute Lagrangian Chemisrty/Transport System. In most cases, the relative sampling error is in the range of 0-20%. The strongest impact of sampling biases is found where the species' temporal gradients are strongest (mostly at sunrise and sunset

  6. Novel germanetellones: XYGe=Te (X, Y = H, F, Cl, Br, I and CN) - structures and energetics. Comparison with the first synthetic successes.

    PubMed

    Jaufeerally, Naziah B; Abdallah, Hassan H; Ramasami, Ponnadurai; Schaefer, Henry F

    2014-03-14

    No stable germanetellone was described until Tbt(Dis)Ge=Te and Tbt(Tip)Ge=Te (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Dis = bis(trimethylsilyl)methyl and Tip = 2,4,6-triisopropylphenyl) were reported in 1997. Following these initial experiments, there has arisen considerable interest in Ge[double bond, length as m-dash]Te systems. An obvious question is: why have the simple XYGe=Te (X, Y = H, F, Cl, Br, I and CN) molecules not yet been isolated? In view of the present situation, theoretical information may be of great help for further advances in germanetellone chemistry. A systematic investigation of the XYGe=Te molecules is carried out using the second order Møller-Plesset perturbation theory (MP2) and density functional theory (DFT). The structures and energetics, including ionization potentials (IPad and IPad(ZPVE)), four different forms of neutral-anion separations (EAad, EAad(ZPVE), VEA and VDE) and the singlet-triplet gaps, are reported. The electronegativity (χ) reactivity descriptor for the halogens (F, Cl, Br and I) and the natural charge separations of the Ge=Te moiety are used to assess the interrelated properties of germanetellone and its derivatives. The results are analyzed, discussed and compared with analogous studies of telluroformaldehyde, silanetellone and their derivatives. The thermodynamic viabilities of some of the novel germanetellones have also been evaluated in terms of the bond dissociation enthalpies of Tbt(Dis)Ge=Te and Tbt(Tip)Ge=Te. The simple mono-substituted germanetellones appear to be slightly more thermodynamically favored than Tbt(Dis)Ge=Te and Tbt(Tip)Ge=Te, since the bond dissociation enthalpies of these kinetically stabilized germanetellones are about 28 and 51 kcal mol(-1) lower, respectively.

  7. Electrochemical Codeposition of Al-Li-Mg Alloys at Solid Aluminum Electrode from LiCl-KCl-MgCl2 Molten Salt System

    NASA Astrophysics Data System (ADS)

    Ye, Ke; Zhang, Mi Lin; Chen, Ye; Han, Wei; de Yan, Yong; Cao, Peng

    2010-06-01

    The electrochemical codeposition of Mg and Li at an aluminium electrode in LiCl-KCl (50:50 wt pct) melts containing different concentrations of MgCl2 at 893 K (620 °C) to form Al-Li-Mg alloys was investigated. Cyclic voltammograms showed that the potential of Li metal deposition at an Al electrode, before the addition of MgCl2, is more positive than that of Li metal deposition at an Mo electrode, which indicated the formation of an Al-Li alloy. The underpotential deposition of magnesium at an aluminium electrode leads to the formation of Al-Mg alloys, and the succeeding underpotential deposition of lithium on predeposited Al-Mg alloys leads to the formation of Al-Li-Mg alloys. Chronopotentiometric measurements indicated that the codeposition of Mg and Li occurs at current densities lower than -0.668 A cm-2 in LiCl-KCl-MgCl2 (8 wt pct) melts at an aluminium electrode. The chronoamperometric studies indicated that the onset potential for the codeposition of Mg and Li is -2.000 V, and the codeposition of Mg and Li at an aluminium electrode is formed into Al-Li-Mg alloys when the applied potentials are more negative than -2.000 V. X-ray diffraction and inductively coupled plasma analysis indicated that Al-Li-Mg alloys with different lithium and magnesium contents were prepared via potentiostatic and galvanostatic electrolysis. The microstructure of typical dual phases of the Al-Li-Mg alloy was characterized by an optical microscope and by scanning electron microscopy. The analysis of energy dispersive spectrometry showed that the elements of Al and Mg distribute homogeneously in the Al-Li-Mg alloy. The lithium and magnesium contents of Al-Li-Mg alloys can be controlled by MgCl2 concentrations and by electrolytic parameters.

  8. S = 1/2 Square-Lattice Antiferromagnets: (CuX)LaB_2O_7 and (CuCl)A_2B_3O10 (X = Cl, Br; A = Ca, Sr; B = Nb, Ta)

    NASA Astrophysics Data System (ADS)

    Kageyama, H.; Kitano, T.; Nakanishi, R.; Yasuda, J.; Oba, N.; Baba, Y.; Nishi, M.; Ueda, Y.; Ajiro, Y.; Yoshimura, K.

    A series of magnetic compounds with the formula (CuX)LaB_2O_7 and (CuCl)A_2B_3O10 (X = Cl, Br; A = Ca, Sr; B = Nb, Ta) have been prepared through a low-temperature topochemical route starting from nonmagnetic double- (n = 2) and triple- (n = 3) layered perovskites, respectively. The magnetic susceptibility of these compounds typically exhibits a broad maximum at low temperatures, characteristic of low-dimensional antiferromagnetic compounds. However, depending on the choice of the parameters, X, A, B and n, physical quantities such as the Weiss temperature and the temperature at a maximum susceptibility vary to a great extent, which enables us to study the phase diagram of the S = 1/2 frustrated square-lattice antiferromagnets (the so-called J_1-J_2 model). In particular, (CuCl)LaNb_2O_7, possibly having a ferromagnetic J_1 and an antiferromagnetic J_2, shows a spin-liquid behavior with the spin gap of 27 K.

  9. Influence of sodium halides (NaF, NaCl, NaBr, NaI) on the photocatalytic performance of hydrothermally synthesized hematite photoanodes.

    PubMed

    Wang, Tsinghai; Huang, Mao-Chia; Hsieh, Yi-Kong; Chang, Wen-Sheng; Lin, Jing-Chie; Lee, Chih-Hao; Wang, Chu-Fang

    2013-08-28

    It has been suggested that a high concentration of Fe(3+) in solution, a low pH, and noncomplexing ions of high ionic strength are all essential for developing a high-quality hematite array. Our curiosity was piqued regarding the role of the electrolyte ions in the hydrothermal synthesis of hematite photoanodes. In this study, we prepared hematite photoanodes hydrothermally from precursor solutions of 0.1 M FeCl3 at pH 1.55 with a background electrolyte of 1.0 M sodium halide (NaF, NaCl, NaBr, or NaI). We compared the structures and properties of the as-obtained hematite photoanodes with those of the material prepared in 1.0 M NaNO3, the most widely adopted electrolyte in previous studies. Among our studied systems, we found that the hematite photoanode prepared in NaCl solution was the only one possessing properties similar to those of the sample obtained from the NaNO3 solution-most importantly in terms of photoelectrochemical performance (ca. 0.2 mA/cm(2) with +0.4 V vs SCE). The hematites obtained from the NaF, NaBr, and NaI solutions exhibited much lower (by approximately 2 orders of magnitude) photocurrent densities under the same conditions, possibly because of their relatively less ordered crystallinity and the absence of rodlike morphologies. Because the synthetic protocol was identical in each case, we believe that these two distinct features reflect the environments in which these hematite photoanodes were formed. Consistent with the latest studies reported in the literature of the X-ray photoelectron spectra of fast-frozen hematite colloids in aqueous solutions, it appears that the degree of surface ion loading at the electrolyte-hematite interface (Stern layer) is critical during the development of hematite photoanodes. We suspect that a lower ion surface loading benefits the hematite developing relatively higher-order and a rodlike texture, thereby improving the photoelectrochemical activity.

  10. On the formation of U Al alloys in the molten LiCl KCl eutectic

    NASA Astrophysics Data System (ADS)

    Cassayre, L.; Caravaca, C.; Jardin, R.; Malmbeck, R.; Masset, P.; Mendes, E.; Serp, J.; Soucek, P.; Glatz, J.-P.

    2008-08-01

    U-Al alloy formation has been studied in the temperature range of 400-550 °C by electrochemical techniques in the molten LiCl-KCl eutectic. Cyclic voltammetry showed that underpotential reduction of U(III) onto solid Al occurs at a potential about 0.35 V more anodic than pure U deposition. Open circuit potential measurements, recorded after small depositions of U metal onto the Al electrode, did not allow the distinction between potentials associated with UAl x alloys and the Al rest potential, as they were found to be practically identical. As a consequence, a spontaneous chemical reaction between dissolved UCl 3 and Al is thermodynamically possible and was experimentally observed. Galvanostatic electrolyses were carried out both on Al rods and Al plates. Stable and dense U-Al deposits were obtained with high faradic yields, and the possibility to load the whole bulk of a thin Al plate was demonstrated. The analyses (by SEM-EDX and XRD) of the deposits indicated the formation of different intermetallic phases (UAl 2, UAl 3 and UAl 4) depending on the experimental conditions.

  11. Influence of the PsbA1/PsbA3, Ca(2+)/Sr(2+) and Cl(-)/Br(-) exchanges on the redox potential of the primary quinone Q(A) in Photosystem II from Thermosynechococcus elongatus as revealed by spectroelectrochemistry.

    PubMed

    Kato, Yuki; Shibamoto, Tadao; Yamamoto, Shoichi; Watanabe, Tadashi; Ishida, Naoko; Sugiura, Miwa; Rappaport, Fabrice; Boussac, Alain

    2012-11-01

    Ca(2+) and Cl(-) ions are essential elements for the oxygen evolution activity of photosystem II (PSII). It has been demonstrated that these ions can be exchanged with Sr(2+) and Br(-), respectively, and that these ion exchanges modify the kinetics of some electron transfer reactions at the Mn₄Ca cluster level (Ishida et al., J. Biol. Chem. 283 (2008) 13330-13340). It has been proposed from thermoluminescence experiments that the kinetic effects arise, at least in part, from a decrease in the free energy level of the Mn(4)Ca cluster in the S₃ state though some changes on the acceptor side were also observed. Therefore, in the present work, by using thin-layer cell spectroelectrochemistry, the effects of the Ca(2+)/Sr(2+) and Cl(-)/Br(-) exchanges on the redox potential of the primary quinone electron acceptor Q(A), E(m)(Q(A)/Q(A)(-)), were investigated. Since the previous studies on the Ca(2+)/Sr(2+) and Cl(-)/Br(-) exchanges were performed in PsbA3-containing PSII purified from the thermophilic cyanobacterium Thermosynechococcus elongatus, we first investigated the influences of the PsbA1/PsbA3 exchange on E(m)(Q(A)/Q(A)(-)). Here we show that i) the E(m)(Q(A)/Q(A)(-)) was up-shifted by ca. +38mV in PsbA3-PSII when compared to PsbA1-PSII and ii) the Ca(2+)/Sr(2+) exchange up-shifted the E(m)(Q(A)/Q(A)(-)) by ca. +27mV, whereas the Cl(-)/Br(-) exchange hardly influenced E(m)(Q(A)/Q(A)(-)). On the basis of the results of E(m)(Q(A)/Q(A)(-)) together with previous thermoluminescence measurements, the ion-exchange effects on the energetics in PSII are discussed.

  12. Effect of AlCl3 concentration on nanoparticle removal by coagulation.

    PubMed

    Zhang, Lizhu; Mao, Jingchun; Zhao, Qing; He, Shaobo; Ma, Jun

    2015-12-01

    In recent years, engineered nanoparticles, as a new group of contaminants emerging in natural water, have been given more attention. In order to understand the behavior of nanoparticles in the conventional water treatment process, three kinds of nanoparticle suspensions, namely multi-walled carbon nanotube-humic acid (MWCNT-HA), multi-walled carbon nanotube-N,N-dimethylformamide (MWCNT-DMF) and nanoTiO2-humic acid (TiO2-HA) were employed to investigate their coagulation removal efficiencies with varying aluminum chloride (AlCl3) concentrations. Results showed that nanoparticle removal rate curves had a reverse "U" shape with increasing concentration of aluminum ion (Al(3+)). More than 90% of nanoparticles could be effectively removed by an appropriate Al(3+) concentration. At higher Al(3+) concentration, nanoparticles would be restabilized. The hydrodynamic particle size of nanoparticles was found to be the crucial factor influencing the effective concentration range (ECR) of Al(3+) for nanoparticle removal. The ECR of Al(3+) followed the order MWCNT-DMF>MWCNT-HA>TiO2-HA, which is the reverse of the nanoparticle size trend. At a given concentration, smaller nanoparticles carry more surface charges, and thus consume more coagulants for neutralization. Therefore, over-saturation occurred at relatively higher Al(3+) concentration and a wider ECR was obtained. The ECR became broader with increasing pH because of the smaller hydrodynamic particle size of nanoparticles at higher pH values. A high ionic strength of NaCl can also widen the ECR due to its strong potential to compress the electric double layer. It was concluded that it is important to adjust the dose of Al(3+) in the ECR for nanoparticle removal in water treatment.

  13. Metal-Metal Bonding in Trinuclear, Mixed-Valence [Ti3X12](4-) (X = F, Cl, Br, I) Face-Shared Complexes.

    PubMed

    Hewage, Jinasena W; Cavigliasso, Germán; Stranger, Robert

    2015-11-16

    Metal-metal bonding in structurally characterized In4Ti3Br12, comprising linear, mixed-valence d(1)d(2)d(1) face-shared [Ti3Br12](4-) units with a Ti-Ti separation of 3.087 Å and strong antiferromagnetic coupling (Θ = -1216 K), has been investigated using density functional theory. The antiferromagnetic configuration, in which the single d electron on each terminal Ti(III) (d(1)) metal center is aligned antiparallel to the two electrons occupying the central Ti(II) (d(2)) metal site, is shown to best agree with the reported structural and magnetic data and is consistent with an S = 0 ground state in which two of the four metal-based electrons are involved in a two-electron, three-center σ bond between the Ti atoms (formal Ti-Ti bond order of ∼0.5). However, the unpaired spin densities on the Ti sites indicate that while the metal-metal σ interaction is strong, the electrons are not fully paired off and consequently dominate the ground state antiferromagnetic coupling. The same overall partially delocalized bonding regime is predicted for the other three halide [Ti3X12](4-) (X = F, Cl, I) systems with the metal-metal bonding becoming weaker as the halide group is descended. The possibility of bond-stretch isomerism was also examined where one isomer has a symmetric structure with identical Ti-Ti bonds while the other is unsymmetric with one short and one long Ti-Ti bond. Although calculations indicate that the latter form is more stable, the barrier to interconversion between equivalent unsymmetric forms, where the short Ti-Ti bond is on one side of the trinuclear unit or the other, is relatively small such that at room temperature only the averaged (symmetric) structure is likely to be observed.

  14. Dinuclear Metallacycles with Single M-X-M Bridges (X = Cl(-), Br(-); M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)): Strong Antiferromagnetic Superexchange Interactions.

    PubMed

    Reger, Daniel L; Pascui, Andrea E; Foley, Elizabeth A; Smith, Mark D; Jezierska, Julia; Wojciechowska, Agnieszka; Stoian, Sebastian A; Ozarowski, Andrew

    2017-03-06

    A series of monochloride-bridged, dinuclear metallacycles of the general formula [M2(μ-Cl)(μ-L)2](ClO4)3 have been prepared using the third-generation, ditopic bis(pyrazolyl)methane ligands L = m-bis[bis(1-pyrazolyl)methyl]benzene (Lm), M = Cu(II), Zn(II), and L = m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (Lm*), M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II). These complexes were synthesized from the direct reactions of M(ClO4)2·6H2O, MCl2, and the ligand, Lm or Lm*, in the appropriate stoichiometric amounts. Three analogous complexes of the formula [M2(μ-Cl)(μ-L)2](BF4)3, L = Lm, M = Cu(II), and L = Lm*, M = Co(II), Cu(II), were prepared from the reaction of [M2(μ-F)(μ-L)2](BF4)3 and (CH3)3SiCl. The bromide-bridged complex [Cu2(μ-Br)(μ-Lm*)2](ClO4)3 was prepared by the first method. Three acyclic complexes, [Co2(μ-Lm)μ-Cl4], [Co2(μ-Lm*)Cl4], and [Co2(μ-Lm*)Br4], were also prepared. The structures of all [M2(μ-X)(μ-L)2](3+) (X = Cl(-), Br(-)) complexes have two ditopic bis(pyrazolyl)methane ligands bridging two metals in a metallacyclic arrangement. The fifth coordination site of the distorted trigonal bipyramidal metal centers is filled by a bridging halide ligand that has an unusual linear or nearly linear M-X-M angle. The NMR spectra of [Zn2(μ-Cl)(μ-Lm*)2](ClO4)3 and especially [Cd2(μ-Cl)(μ-Lm*)2](ClO4)3 demonstrate that the metallacycle structure is maintained in solution. Solid state magnetic susceptibility data for the copper(II) compounds show very strong antiferromagnetic exchange interactions, with -J values of 536 cm(-1) for [Cu2(μ-Cl)(μ-Lm)2](ClO4)3·xCH3CN, 720 cm(-1) for [Cu2(μ-Cl)(μ-Lm*)2](ClO4)3, and 945 cm(-1) for [Cu2(μ-Br)(μ-Lm*)2](ClO4)3·2CH3CN. Smaller but still substantial antiferromagnetic interactions are observed with other first row transition metals, with -J values of 98 cm(-1) for [Ni2(μ-Cl)(μ-Lm*)2](ClO4)3, 55 cm(-1) for [Co2(μ-Cl)(μ-Lm*)2](ClO4)3, and 34 cm(-1) for [Fe2(μ-Cl)(μ-Lm*)2](ClO4

  15. The staging mechanism of AlCl4 intercalation in a graphite electrode for an aluminium-ion battery.

    PubMed

    Bhauriyal, Preeti; Mahata, Arup; Pathak, Biswarup

    2017-03-15

    Identifying a suitable electrode material with desirable electrochemical properties remains a primary challenge for rechargeable Al-ion batteries. Recently an ultrafast rechargeable Al-ion battery was reported with high charge/discharge rate, (relatively) high discharge voltage and high capacity that uses a graphite-based cathode. Using calculations from first-principles, we have investigated the staging mechanism of AlCl4 intercalation into bulk graphite and evaluated the stability, specific capacity and voltage profile of AlCl4 intercalated compounds. Ab initio molecular dynamics is performed to investigate the thermal stability of AlCl4 intercalated graphite structures. Our voltage profiles show that the first AlCl4 intercalation step could be a more sluggish step than the successive intercalation steps. However, the diffusion of AlCl4 is very fast in the expanded graphite host layers with a diffusion barrier of ∼0.01 eV, which justifies the ultrafast charging rate of a graphite based Al-ion battery. And such an AlCl4 intercalated battery provides an average voltage of 2.01-2.3 V with a maximum specific capacity of 69.62 mA h g(-1), which is excellent for anion intercalated batteries. Our density of states and Bader charge analysis shows that the AlCl4 intercalation into the bulk graphite is a charging process. Hence, we believe that our present study will be helpful in understanding the staging mechanism of AlCl4 intercalation into graphite-like layered electrodes for Al-ion batteries, thus encouraging further experimental work.

  16. Kinetics of Hg X ( B - X ) formation due to collisions of Ar sup + sub 2 ions with CH sub 3 Hg X ( X =Cl, Br, I) molecules related to blue-green laser emission

    SciTech Connect

    Mahmood, M.F. )

    1990-03-26

    Collisional behavior of Hg{ital X} ({ital B} state) ({ital X}=Cl, Br, I) has been studied during collisions of Ar{sup +}{sub 2} ions with CH{sub 3}Hg{ital X} ({ital X}=Cl, Br, I) molecules in the kinetic energy (lab.) range 100--1000 eV. By using the integrated intensity of the most intense band of the ({ital B}, {ital v}{prime}=0{endash}{ital X}, {ital v}{double prime}=22) transitions in HgCl, HgBr, and HgI at 558, 502, and 443 nm, respectively, emission cross sections were measured at various kinetic energies of the projectile ions. The maximum values of these cross sections for dissociative excitation were found to be 3.8{times}10{sup {minus}19}, 5.7{times}10{sup {minus}19}, and 6.1{times}10{sup {minus}19} cm{sup 2} for HgCl ({ital B}), HgBr ({ital B}), and HgI ({ital B}), respectively.

  17. Synthesis and single-crystal structure determination of the zinc nitride halides Zn{sub 2}NX (X=Cl, Br, I)

    SciTech Connect

    Liu, Xiaohui; Wessel, Claudia; Pan, Fangfang; Dronskowski, Richard

    2013-07-15

    A series of zinc nitride halides, Zn{sub 2}NX (X=Cl, Br, I), has been synthesized from solid–liquid reactions of zinc nitride with the respective zinc halides under vacuum, and their crystal structures were determined using single-crystal and powder X-ray diffraction. While Zn{sub 2}NCl and Zn{sub 2}NBr crystallize in the acentric orthorhombic space group Pna2{sub 1}, Zn{sub 2}NI adopts the centrosymmetric space group Pnma; Zn{sub 2}NCl and Zn{sub 2}NBr can be considered to belong to the anti-β-NaFeO{sub 2} type, and Zn{sub 2}NI is closely related. Each N{sup 3−} is tetrahedrally coordinated by zinc atoms, and the X{sup −} anions are located in the vacancies of the framework formed by corner-sharing [NZn{sub 4}] tetrahedra. According to TGA/DTA analyses, the Zn{sub 2}NX compounds exhibit good thermal stability. The electronic structure has been analyzed by employing density-functional theory and the HSE06 hybrid functional. - Graphical abstract: Zn{sub 2}NCl, Zn{sub 2}NBr, and Zn{sub 2}NI have been synthesized, and their crystal structures (Cl and Br phases: Pna2{sub 1}; I phase: Pnma) have been determined from XRD; the direct band gap of Zn{sub 2}NCl is theoretically (HSE06 hybrid functional) predicted as 3.7 eV. - Highlights: • Zn{sub 2}NCl, Zn{sub 2}NBr, and Zn{sub 2}NI have been synthesized from solid–liquid reactions. • The crystal structures of Zn{sub 2}NCl, Zn{sub 2}NBr, and Zn{sub 2}NI have been determined from single-crystal X-ray diffraction. • Zn{sub 2}NCl and Zn{sub 2}NBr crystallize in the acentric space group Pna2{sub 1} whereas Zn{sub 2}NI adopts the centrosymmetric space group Pnma. • Zn{sub 2}NCl and Zn{sub 2}NBr are stable up to 750 °C whereas Zn{sub 2}NI decays at 600 °C already. • The direct band gap of Zn{sub 2}NCl is theoretically predicted as 3.7 eV using the HSE06 hybrid functional.

  18. Halogen-π Interactions between Benzene and X2/CX4 (X = Cl, Br): Assessment of Various Density Functionals with Respect to CCSD(T).

    PubMed

    Youn, Il Seung; Kim, Dong Yeon; Cho, Woo Jong; Madridejos, Jenica Marie L; Lee, Han Myoung; Kołaski, Maciej; Lee, Joonho; Baig, Chunggi; Shin, Seung Koo; Filatov, Michael; Kim, Kwang S

    2016-11-23

    Various types of interactions between halogen (X) and π moiety (X-π interaction) including halogen bonding play important roles in forming the structures of biological, supramolecular, and nanomaterial systems containing halogens and aromatic rings. Furthermore, halogen molecules such as X2 and CX4 (X = Cl/Br) can be intercalated in graphite and bilayer graphene for doping and graphene functionalization/modification. Due to the X-π interactions, though recently highly studied, their structures are still hardly predictable. Here, using the coupled-cluster with single, double, and noniterative triple excitations (CCSD(T)), the Møller-Plesset second-order perturbation theory (MP2), and various flavors of density functional theory (DFT) methods, we study complexes of benzene (Bz) with halogen-containing molecules X2 and CX4 (X = Cl/Br) and analyze various components of the interaction energy using symmetry adapted perturbation theory (SAPT). As for the lowest energy conformers (S1), X2-Bz is found to have the T-shaped structure where the electropositive X atom-end of X2 is pointing to the electronegative midpoint of CC bond of the Bz ring, and CX4-Bz has the stacked structure. In addition to this CX4-Bz (S1), other low energy conformers of X2-Bz (S2/S3) and CX4-Bz (S2) are stabilized primarily by the dispersion interaction, whereas the electrostatic interaction is substantial. Most of the density functionals show noticeable deviations from the CCSD(T) complete basis set (CBS) limit binding energies, especially in the case of strongly halogen-bonded conformers of X2-Bz (S1), whereas the deviations are relatively small for CX4-Bz where the dispersion is more important. The halogen bond shows highly anisotropic electron density around halogen atoms and the DFT results are very sensitive to basis set. The unsatisfactory performance of many density functionals could be mainly due to less accurate exchange. This is evidenced from the good performance by the dispersion

  19. Location and function of the high-affinity chloride in the oxygen-evolving complex--implications from comparing studies on Cl(-)/Br(-)/I(-)-substituted photosystem II prepared using two different methods.

    PubMed

    Wang, Luan; Zhang, Chunxi; Zhao, Jingquan

    2014-09-05

    The high-affinity chloride ion (Cl(-)) is known to play a key role in water oxidation in photosystem II (PSII). Recent crystallographic studies revealed two Cl(-) binding sites in PSII. To examine whether these two Cl(-) ions are correlated to the high-affinity Cl(-), we prepared Cl(-)/Br(-)/I(-)-substituted PSII samples from both higher plants and cyanobacteria by using two different protocols: one was the method used in the crystallographic study (Type 1) and the other was a method developed recently to ensure the efficient replacement of Cl(-) (Type 2). While only minor effects were observed in the Type 1 preparation, efficient Br(-)/I(-)substitution by the Type 2 protocol led to significant changes in the EPR properties of the oxygen-evolving complex (OEC) and the TyrZ, as well as in oxygen-evolving activities. These results are discussed in terms of the binding site of the high-affinity Cl(-) relative to the two Cl(-) ions revealed by the recent X-ray structural data.

  20. Electrodeposition of Mg-Li-Al-La Alloys on Inert Cathode in Molten LiCl-KCl Eutectic Salt

    NASA Astrophysics Data System (ADS)

    Han, Wei; Chen, Qiong; Sun, Yi; Jiang, Tao; Zhang, Milin

    2011-12-01

    Electrochemical preparation of Mg-Li-Al-La alloys on inert electrodes was investigated in LiCl-KCl melt at 853 K (580 °C). Cyclic voltammograms (CVs) and square wave voltammograms (SWVs) show that the existence of AlCl3 or AlF3 could promote La deposition on an active Al substrate, which is predeposited on inert electrodes. All electrochemical tests show that the reduction of La3+ is a one-step reduction process with three electrons exchanged. The reduction of La(III)→La(0) occurred at -2.04 V, and the underpotential deposition (UPD) of La was detected at -1.55 V ( vs Ag/AgCl). The same phenomena concerning La UPD were observed on two inert cathodes, W and Mo. In addition, Mg-Li-Al-La alloys were obtained by galvanostatic electrolysis on the W cathode from La2O3 in LiCl-KCl-MgCl2-KF melts with aluminum as the anode. X-ray diffraction (XRD) measurements indicated that various phases like the Al2La, Al12Mg17, and βLi phase (LiMg/Li3Mg7) existed in the Mg-Li-Al-La alloys. The distribution of Mg, Al, and La in Mg-Li-Al-La alloys from the analysis of a scan electron micrograph (SEM) and energy dispersive spectrometry (EDS) indicated that the elements Mg, Al, and La distributed homogeneously in the alloys.

  1. Simulation calculations of efficiencies and silicon consumption for CH3NH3PbI3‑x‑y Br x Cl y /crystalline silicon tandem solar cells

    NASA Astrophysics Data System (ADS)

    Zhang, Lili; Xie, Ziang; Tian, Fuyang; Qin, Guogang

    2017-04-01

    Much attention has been paid to two-subcell tandem solar cells (TSCs) with crystalline silicon (c-Si) as the bottom cell (TSC-Si). Previous works have pointed out that the optimal band gap, E g, of the top cell material for a TSC-Si is around 1.75 eV. With a tunable E g and better stability than MAPbI3 (MA  =  CH3NH3), MAPbI3‑x‑y Br x Cl y is a promising candidate for the top cell material of a TSC-Si. In this work, calculations concerning the E g, refractive index and extinction coefficient of MAPbI3‑x‑y Br x Cl y are performed using first-principles calculations including the spin–orbit coupling (SOC) effect. MAPbI3‑x‑y Br x Cl y with five sets of x and y, which have a E g around 1.75 eV, are obtained. On this basis, absorption of the perovskite top cell is calculated applying the Lambert–Beer model (LBM) and the transfer matrix model (TMM), respectively. Considering the Auger recombination in the c-Si bottom cell and radiation coupling between the two subcells, the efficiencies for MAPbI3‑x‑y Br x Cl y /c-Si TSCs with the five sets of x and y are calculated. Among them, the MAPbI2.375Br0.5Cl0.125/c-Si TSC achieves the highest efficiency of 35.1% with a 440 nm thick top cell and 50 µm thick c-Si when applying the LBM. When applying the TMM, the highest efficiency of 32.5% is predicted with a 580 nm thick MAPbI2.375Br0.5Cl0.125 top cell and 50 µm thick c-Si. Compared with the limiting efficiency of 27.1% for a 190 µm thick c-Si single junction solar cell (SC), the MAPbI2.375Br0.5Cl0.125/c-Si TSC shows a superior performance of high efficiency and low c-Si consumption.

  2. Structural, spectroscopic, and multiconfigurational quantum chemical investigations of the electron-rich metal-metal triple-bonded Tc(2)X(4)(PMe(3))(4) (X = Cl, Br) complexes.

    PubMed

    Poineau, Frederic; Forster, Paul M; Todorova, Tanya K; Gagliardi, Laura; Sattelberger, Alfred P; Czerwinski, Kenneth R

    2010-07-19

    The compounds Tc(2)Cl(4)(PMe(3))(4) and Tc(2)Br(4)(PMe(3))(4) were formed from the reaction between (n-Bu(4)N)(2)Tc(2)X(8) (X = Cl, Br) and trimethylphosphine. The Tc(II) dinuclear species were characterized by single-crystal XRD, UV-visible spectroscopy, and cyclic voltammetry techniques, and the results are compared to those obtained from density functional theory and multiconfigurational (CASSCF/CASPT2) quantum chemical studies. The compound Tc(2)Cl(4)(PMe(3))(4) crystallizes in the monoclinic space group C2/c [a = 17.9995(9) A, b = 9.1821(5) A, c = 17.0090(9) A, beta = 115.4530(10) degrees ] and is isostructural to M(2)Cl(4)(PMe(3))(4) (M = Re, Mo, W) and to Tc(2)Br(4)(PMe(3))(4). The metal-metal distance (2.1318(2) A) is similar to the one found in Tc(2)Br(4)(PMe(3))(4) (2.1316(5) A). The calculated molecular structures of the ground states are in excellent agreement with the structures determined experimentally. Calculations of effective bond orders for Tc(2)X(8)(2-) and Tc(2)X(4)(PMe(3))(4) (X = Cl, Br) indicate stronger pi bonds in the Tc(2)(4+) core than in Tc(2)(6+) core. The electronic spectra were recorded in benzene and show a series of low intensity bands in the range 10 000-26 000 cm(-1). Assignment of the bands as well as computing their excitation energies and intensities were performed at both TD-DFT and CASSCF/CASPT2 levels of theory. Calculations predict that the lowest energy band corresponds to the delta* --> sigma* transition, the difference between calculated and experimental values being 228 cm(-1) for X = Cl and 866 cm(-1) for X = Br. The next bands are attributed to delta* --> pi*, delta --> sigma*, and delta --> pi* transitions. The cyclic voltammograms exhibit two reversible waves and indicate that Tc(2)Br(4)(PMe(3))(4) exhibits more positive oxidation potentials than Tc(2)Cl(4)(PMe(3))(4.) This phenomenon is discussed and ascribed to stronger metal (d) to halide (d) back bonding in the bromo complex. Further analysis indicates that Tc

  3. Atmospheric aerosol models for systems including the ions H+, NH4+, Na+, SO42-, NO3-, Cl-, Br-, and H2O

    NASA Astrophysics Data System (ADS)

    Wexler, Anthony S.; Clegg, Simon L.

    2002-07-01

    Mole fraction based equations for aqueous phase activities, together with equilibrium constants for the formation of gases and solids, have been combined with a Gibbs free energy minimization algorithm to create equilibrium phase partitioning models of inorganic atmospheric aerosols. The water content, phase state (solid or liquid), and gas/aerosol partitioning are predicted for known ionic composition, relative humidity, and temperature. The models are valid from <200 to 328 K for the subsystems (H+-SO42--NO3--Cl--Br--H2O) and (H+-NH4+-SO42--NO3--H2O), and 298.15 K only for (H+-NH4+-Na+-SO42--NO3--Cl--H2O). The models involve no simplifying assumptions and include all solid phases identified in bulk experiments, including hydrated and double salt forms not treated in most other studies. The Henry's law constant of H2SO4 is derived as a function of temperature, based upon available data, and the model treatment of the solubility of HBr in aqueous H2SO4 is revised. Phase diagrams are calculated for the (NH4)2SO4/H2SO4/H2O system to low temperature. The models are also used to explore the importance of the double salts in urban inorganic aerosols. These Aerosol Inorganics Model (AIM) models can be run on the Web for a variety of problem types at http://mae.ucdavis.edu/wexler/aim.html and http://www.uea.ac.uk/~e770/aim.html, and their use is summarized here.

  4. Resonance Character of Copper/Silver/Gold Bonding in Small Molecule⋅⋅⋅M-X (X=F, Cl, Br, CH3, CF3) Complexes.

    PubMed

    Zhang, Guiqiu; Yue, Huanjing; Weinhold, Frank; Wang, Hui; Li, Hong; Chen, Dezhan

    2015-08-03

    The resonance character of Cu/Ag/Au bonding is investigated in B⋅⋅⋅M-X (M=Cu, Ag, Au; X=F, Cl, Br, CH3, CF3; B=CO, H2O, H2S, C2H2, C2H4) complexes. The natural bond orbital/natural resonance theory results strongly support the general resonance-type three-center/four-electron (3c/4e) picture of Cu/Ag/Au bonding, B:M-X↔B(+) -M:X(-) , which mainly arises from hyperconjugation interactions. On the basis of such resonance-type bonding mechanisms, the ligand effects in the more strongly bound OC⋅⋅⋅M-X series are analyzed, and distinct competition between CO and the axial ligand X is observed. This competitive bonding picture directly explains why CO in OC⋅⋅⋅Au-CF3 can be readily replaced by a number of other ligands. Additionally, conservation of the bond order indicates that the idealized relationship bB⋅⋅⋅M +bMX =1 should be suitably generalized for intermolecular bonding, especially if there is additional partial multiple bonding at one end of the 3c/4e hyperbonded triad.

  5. Amorphization-induced strong localization of electronic states in CsPbBr3 and CsPbCl3 studied by optical absorption measurements

    NASA Astrophysics Data System (ADS)

    Kondo, S.; Sakai, T.; Tanaka, H.; Saito, T.

    1998-11-01

    Optical absorption spectra of amorphous CsPbX3 films (X=Br,Cl) are characterized by two Gaussian bands near the fundamental edge, with the optical energy gap largely blueshifted and the absorption intensity strongly reduced as compared with the crystalline films. The peak energies of the bands are close to those of the A and C bands of Pb-doped alkali halides. The spectral features are discussed in terms of a molecular orbital theory based on a quasicomplex Pb2+(X-)6 model similar to the complex model for the doped alkali halides. It is shown that not only Pb2+ 6s and 6p extended states near the band edges but also X- p states contributing to upper valence bands are localized by amorphization. The transitions from the localized Pb2+ 6s to 6p states produce the spin-orbit allowed 3P1 and dipole allowed 1P1 states responsible for the two Gaussians. The localized X- p states lie deeper in energy than the localized Pb2+ 6s state and only contribute to higher-energy absorption above the Gaussian bands, giving the reason for the reduced absorption near the fundamental edge. The blueshift of the optical energy gap is attributed to the disappearance of k dispersions for these one-electron states.

  6. Electronic structure, photoemission spectra, and vacuum-ultraviolet optical spectra of CsPbCl3 and CsPbBr3

    NASA Astrophysics Data System (ADS)

    Heidrich, K.; Schäfer, W.; Schreiber, M.; Söchtig, J.; Trendel, G.; Treusch, J.; Grandke, T.; Stolz, H. J.

    1981-11-01

    Optical spectra of CsPbCl3 and CsPbBr3 have been measured in the range from 2 to 10 eV and have been combined with ultraviolet-photoemission-spectroscopy (UPS)-measurements at 21.1 and 40.8 eV. A quantitative band calculation is presented, which takes into account anion-anion interaction as well as electronic states of the Cs+ ion. The prominent features of earlier band models and measurements are reestablished through our measurements and calculations, namely that the valence band consists of anionic p functions and Pb 6s functions, the lowest conduction band being Pb 6p type, and the lowest gap occuring at the R point of the Brillouin zone. Inclusion of a further (Cs 6s-type) conduction band, however, is necessary to bring the calculated joint density of states into agreement with vacuum-ultraviolet optical spectra. The calculated densities of states of the valence bands are in quantitative agreement with those deduced from our UPS measurements.

  7. One-dimensional coordination polymers generated from a new triazole bridging ligand and HgX2 (X = Cl, Br and I): characterization and luminescent properties.

    PubMed

    Qin, Na; Zhao, Chao-Wei; Ma, Jian-Ping; Liu, Qi-Kui; Dong, Yu-Bin

    2012-06-01

    The new 4-amino-1,2,4-triazole asymmetric bridging ligand 4-amino-5-(pyridin-3-yl)-3-[4-(pyridin-4-yl)phenyl]-4H-1,2,4-triazole (L) has been used to generate three novel isomorphic one-dimensional coordination polymers, viz. catena-poly[[tris[dichloridomercury(II)]-bis{μ(3)-4-amino-5-(pyridin-3-yl)-3-[4-(pyridin-4-yl)phenyl]-4H-1,2,4-triazole}] acetonitrile monosolvate], {[Hg(3)Cl(6)(C(18)H(14)N(6))(2)]·CH(3)CN}(n), (I), and the bromido, {[Hg(3)Br(6)(C(18)H(14)N(6))(2)]·CH(3)CN}(n), (II), and iodido, {[Hg(3)I(6)(C(18)H(14)N(6))(2)]·CH(3)CN}(n), (III), analogs. The asymmetric ligand acts as a tridentate ligand to coordinate the three different Hg(II) centers (two of which are symmetry-related). Two ligands and two symmetry-related Hg(II) centers form centrosymmetric rectangular units which are linked into one-dimensional chains via the other unique Hg atoms, which sit on mirror planes. The chains are elaborated into a three-dimensional structure via interchain hydrogen bonds. The acetonitrile solvent molecules are located in ellipsoidal cavities. The luminescent character of these three coordination complexes was investigated in the solid state.

  8. Light-Induced Bistability in Iron(III) Spin-Transition Compounds of 5 X-Salicylaldehyde Thiosemicarbazone (X=H, Cl, Br).

    PubMed

    Yemeli, Eddy W T; Blake, Graeme R; Douvalis, Alexios P; Bakas, Thomas; Alberda van Ekenstein, Gert O R; van Koningsbruggen, Petra J

    2010-10-19

    The iron(III) spin-crossover compounds [Fe(Hthsa)(thsa)]⋅H2 O (1), [Fe(Hth5Clsa)(th5Clsa)2 ]⋅H2 O (2), and [Fe(Hth5Brsa)(th5Brsa)2 ]⋅H2 O (3) (H2 thsa=salicylaldehyde thiosemicarbazone, H2 th5Clsa=5-chlorosalicylaldehyde thiosemicarbazone, and H2 th5Brsa=5-bromosalicylaldehyde thiosemicarbazone) have been synthesized and their spin-transition properties investigated by magnetic susceptibility, Mössbauer spectroscopy, and differential scanning calorimetry measurements. The three compounds exhibit an abrupt spin transition with a thermal hysteresis effect. The more polarizable the substituent on the salicylaldehyde moiety, the more complete is the transition at room temperature with an increased degree of cooperativity. The molecular structures of 1 and 2 in the high-spin state are revealed. The occurrence of the light-induced excited-spin-state trapping phenomenon appears to be dependent on the substituent incorporated into the 5-position of the salicylaldehyde subunit. Whereas the compounds with an electron-withdrawing group (-Br or -Cl) exhibit light-induced trapped excited high-spin states with great longevity of metastability, the halogen-free compound does not, even though strong intermolecular interactions (such as hydrogen-bonding networks and π stacking) operate in the system. For compound 2, the surface level of photoconversion is less than 35 %. In contrast, compound 3 displays full photoexcitation.

  9. Frustration and Dzyaloshinsky-Moriya anisotropy in the kagome francisites Cu3Bi (SeO3)2 O2X (X = Br , Cl )

    NASA Astrophysics Data System (ADS)

    Rousochatzakis, Ioannis; Richter, Johannes; Zinke, Ronald; Tsirlin, Alexander A.

    2015-01-01

    We investigate the antiferromagnetic canting instability of the spin-1/2 kagome ferromagnet, as realized in the layered cuprates Cu3Bi (SeO3)2 O2X (X = Br , Cl ). While the local canting can be explained in terms of competing exchange interactions, the direction of the ferrimagnetic order parameter fluctuates strongly even at short distances on account of frustration which gives rise to an infinite ground state degeneracy at the classical level. In analogy with the kagome antiferromagnet, the accidental degeneracy is fully lifted only by nonlinear 1 /S corrections, rendering the selected uniform canted phase very fragile even for spins-1/2, as shown explicitly by coupled-cluster calculations. To account for the observed ordering, we show that the minimal description of these systems must include the microscopic Dzyaloshinsky-Moriya interactions, which we obtain from density-functional band-structure calculations. The model explains all qualitative properties of the kagome francisites, including the detailed nature of the ground state and the anisotropic response under a magnetic field. The predicted magnon excitation spectrum and quantitative features of the magnetization process call for further experimental investigations of these compounds.

  10. Structure, stability, and nature of bonding in carbon monoxide bound EX3+ complexes (E = group 14 element; X = H, F, Cl, Br, I).

    PubMed

    Ghara, Manas; Pan, Sudip; Kumar, Anand; Merino, Gabriel; Chattaraj, Pratim K

    2016-09-15

    A density functional theory study is performed to predict the structures and stability of carbon monoxide (CO) bound EX3+ (E = C, Si, Ge, Sn, Pb; X = H, F, Cl, Br, I) complexes. The possibility of bonding through both C- and O-sides of CO is considered. Thermochemical analysis reveals that all the dissociation processes producing CO and EX3+ are endothermic in nature whereas most of the dissociation reactions are endergonic in nature at room temperature. The nature of bonding in EC/O bonds is analyzed via Wiberg bond index, natural population analysis, electron density, and energy decomposition analyses in conjunction with natural orbitals for chemical valence scheme. In comparison to CO stretching frequency ( ν∼CO) in free CO, while a red shift is noted in O-side binding, the C-side binding results in a blue shift in ν∼CO. The relative change in ν∼CO values in CO bound EX3+ complexes on changing either E or X is scrutinized and possible explanation is provided in terms of polarization in the σ- and π-orbitals and the relative strength of C→E or O→E σ-donation and E→C or E→O π-back-donation. © 2016 Wiley Periodicals, Inc.

  11. Influence of the reduced dimensionality on the thermodynamical and electrical properties of photosensitive BiOX (X = Cl, Br, and I) semiconductors

    NASA Astrophysics Data System (ADS)

    Lotnyk, D.; Komanický, V.; Feher, A.; Bunda, V.

    2016-12-01

    The influence of the layered structure on the temperature dependencies of the specific heat, thermal conductivity, and electric resistivity of photosensitive bismuth oxyhalides BiOX (X = Cl, Br and I) single crystals were investigated in the temperature range 2 K ≤ T ≤ 300 K. The low temperature specific heat data for BiOX demonstrated the presence of two-dimensional behavior with increased anisotropy for the BiOI sample. Moreover, the thermal conductivity values for BiOI are three times higher than for BiOCl and BiOBr, and this observation is consistent with increased anisotropy arising from the contribution of optical out-of-plane phonons. The influence of green (λ = 532 nm) and red (λ = 640 nm) laser excitations on the electrical conductivity properties has been investigated. Each photoconductivity curve reveals transitions from low to high sensitivity. The depletion temperature region for BiOX single crystals corresponds to the peak in temperature dependence of the charge carrier mobility.

  12. Reaction mechanism studies towards effective fabrication of lithium-rich anti-perovskites Li3OX (X=Cl, Br)

    SciTech Connect

    Li, Shuai; Zhu, Jinlong; Wang, Yonggang; Howard, John W.; Lü, Xujie; Li, Yutao; Kumar, Ravhi S.; Wang, Liping; Daemen, Luke L.; Zhao, Yusheng

    2015-12-10

    Lithium-rich Anti-perovskite (LiRAP), with general formula Li3OX (X = Cl, Br, I), and recently reported as superionic conductors with 3-dimensional Li+ migrating channels, is emerging as a promising candidate for solid electrolyte of all-solid-state LIBs. But, it is still difficult to fabricate pure LiRAP due to the difficulty of the phase formation and moisture-sensitive nature of the products. In this work, we thoroughly studied the formation mechanism of Li3OCl and Li3OBr in various solid state reaction routes. We developed different experimental strategies in order to improve the syntheses, in purposes of improved phase stability and large-scale production of LiRAP. One feasible method is to use strongly reductive agents Li metal or LiH to eliminate OH species. The results show that LiH is more effective than Li metal because of negatively charged H- and uniform reaction. The other well-established method is using Li2O and LiX mixture as reagents to preventing OH phase at the beginning, and using protected ball milling to make fine powders and hence active the reaction. Finally, IR spectroscopy, thermal analyses and first-principle calculation were performed to give indications on the reaction pathway.

  13. Chaos in the classical mechanics of bound and quasi-bound HX-4He complexes with X = F, Cl, Br, CN.

    PubMed

    Gamboa, Antonio; Hernández, Henar; Ramilowski, Jordan A; Losada, J C; Benito, R M; Borondo, F; Farrelly, David

    2009-10-01

    The classical dynamics of weakly bound floppy van der Waals complexes have been extensively studied in the past except for the weakest of all, i.e., those involving He atoms. These complexes are of considerable current interest in light of recent experimental work focussed on the study of molecules trapped in small droplets of the quantum solvent (4)He. Despite a number of quantum investigations, details on the dynamics of how quantum solvation occurs remain unclear. In this paper, the classical rotational dynamics of a series of van der Waals complexes, HX-(4)He with X = F, Cl, Br, CN, are studied. In all cases, the ground state dynamics are found to be almost entirely chaotic, in sharp contrast to other floppy complexes, such as HCl-Ar, for which chaos sets in only at relatively high energies. The consequences of this result for quantum solvation are discussed. We also investigate rotationally excited states with J = 1 which, except for HCN-(4)He, are actually resonances that decay by rotational pre-dissociation.

  14. Enhanced surface modification engineering (H, F, Cl, Br, and NO{sub 2}) of CdS nanowires with and without surface dangling bonds

    SciTech Connect

    Zeng, Yijie; Xing, Huaizhong Lu, Aijiang; Wang, Chunrui; Xu, Xiaofeng; Huang, Yan; Chen, Xiaoshuang E-mail: xschen@mail.sitp.ac.cn; Wang, Jiqing E-mail: xschen@mail.sitp.ac.cn

    2015-08-07

    Semiconductor nanowires (NWs) can be applied in gas sensing and cell detection, but the sensing mechanism is not clearly understood. In this study, surface modification effect on the electronic properties of CdS NWs for different diameters with several species (H, F, Cl, Br, and NO{sub 2}) is investigated by first principles calculations. The surface dangling bonds and halogen elements are chosen to represent the environment of the surface. Halogen passivation drastically changes the band gaps due to the strong electronegativity and the energy level of halogen atoms. Density of states analysis indicates that valence band maximum (VBM) of halogen-passivated NWs is formed by the p states of halogen atoms, while VBM of H-passivated NWs is originated from Cd 4d and S 3p orbitals. To illustrate that surface modification can be applied in gas sensing, NO{sub 2}-absorbed NWs with different coverage are calculated. Low coverage of NO{sub 2} introduces a deep p-type dopant-like level, while high coverage introduces a shallow n-type dopant-like level into the band structure. The transformation is due to that at low coverage the adsorption is chemical while at high coverage is physical. These findings might promote the understanding of surface modification effect and the sensing mechanism of NWs as gas sensors.

  15. Structures and nonlinear optical properties of the endohedral metallofullerene-superhalogen compounds Li@C60-BX4 (X = F, Cl, Br).

    PubMed

    Wang, Shu-Jian; Li, Ying; Wang, Yin-Feng; Wu, Di; Li, Zhi-Ru

    2013-08-21

    It has recently been demonstrated that superatoms, which can exhibit behaviors reminiscent of atoms in the periodic table, might have synthetic utility, and represent potential building blocks for the assembly of novel, nanostructured materials [Science 2004, 304, 84-87; Science 2005, 307, 231-235; J. Phys. Chem. C 2009, 113, 2664]. In this work, a new type of endohedral metallofullerene-superhalogen compound, Li@C60-BX4 (X = F, Cl, Br), is proposed and characterized using density functional theory. The electron transfer from Li@C60 to BX4 contributes greatly to the Li@C60-BX4 compound formation. Such compounds exhibit considerable stabilities with large binding energies and ionization potentials, as well as large HOMO-LUMO gaps. The investigation of the nonlinear optical (NLO) properties of Li@C60-BX4 reveals a strong dependence of the static first hyperpolarizability, β0, on the atomic number of the involved halogen atom X. This means that one can enhance the first hyperpolarizabilities of the endohedral metallofullerene by introducing superhalogens. The present investigation may promote the development of novel nanomaterials with unusual properties (i.e. NLO properties), and enrich the knowledge of chemical bonds (for example, long-range interactions between trapped atoms in a C60 cage and the outside superatom motif).

  16. Synthesis and characterization of novel plasmonic Ag/AgX-CNTs (X = Cl, Br, I) nanocomposite photocatalysts and synergetic degradation of organic pollutant under visible light.

    PubMed

    Shi, Huixian; Chen, Jiangyao; Li, Guiying; Nie, Xin; Zhao, Huijun; Wong, Po-Keung; An, Taicheng

    2013-08-14

    A series of novel well-defined Ag/AgX (X = Cl, Br, I) loaded carbon nanotubes (CNTs) composite photocatalysts (Ag/AgX-CNTs) were fabricated for the first time via a facile ultrasonic assistant deposition-precipitation method at the room temperature (25 ± 1 °C). X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption analysis, scanning electron microscopy, and ultraviolet-visible light absorption spectra analysis were used to characterize the structure, morphology, and optical properties of the as-prepared photocatalysts. Results confirmed the existence of the direct interfacial contact between Ag/AgX nanoparticles and CNTs, and Ag/AgX-CNTs nanocomposites exhibit superior absorbance in the visible light (VL) region owing to the surface plasmon resonance (SPR) of Ag nanoparticles. The fabricated composite photocatalysts were employed to remove 2,4,6-tribromophenol (TBP) in aqueous phase. A remarkably enhanced VL photocatalytic degradation efficiency of Ag/AgX-CNTs nanocomposites was observed when compared to that of pure AgX or CNTs. The photocatalytic activity enhancement of Ag/AgX-CNTs was due to the effective electron transfer from photoexcited AgX and plasmon-excited Ag(0) nanoparticles to CNTs. This can effectively decrease the recombination of electron-hole pairs, lead to a prolonged lifetime of the photoholes that promotes the degradation efficiency.

  17. Increased photovoltaic performance by the optimized TiClI4 and AlCl3 surface treatment in dye-sensitized solar cells.

    PubMed

    Oh, Ju Hee; Kim, Dae-Hwan; Lee, Sang-Ju; Kwak, Giseop; Han, Yoon Soo

    2014-12-01

    The surface of TiO2 photoelectrodes coated on F-doped SnO2 (FTO) was modified by soaking it in a TiCl4:AlCl3 mixed aqueous solution with various molar ratios, and then calcining to produce the TiCl4:AlCl3-treated TiO2 photoelectrode (Ti:Al-TiO2/FTO). The highest power conversion efficiency (PCE) was obtained from dye-sensitized solar cells (DSSC) with Ti:Al(5:5)-TiO2/FTO, which was prepared from the mixed solution with the molar ratio of 5:5 (TiCi4:AlCl3). PCE of DSSC with Ti:Al (5:5)-TiO2/FTO was improved by ca. 19.6%, compared to that of the reference device with Ti:Al (10:0)-TiO2/FTO (i.e., TiO2-coated TiO2/FTO) due to an enhancement in both short-circuit photocurrent (J(sc)) and open-circuit voltage (V(oc)). A series of measurements such as UV-visible absorption, electrochemical impedance, open circuit voltage decay and dark current revealed that the increase in J(sc) was attributed to the improvement of electron collection efficiency by a prolonged electron lifetime, and the suppression of the charge recombination between injected electrons and I3(-) ions was found to increase the V(oc) value of the device with Ti:Al(5:5)-TiO2/FTO.

  18. New k-phase materials, k-(ET) sub 2 Cu(N(CN) sub 2 )X: X = Cl, Br and I: The synthesis, structure and superconductivity above 11 K in the Cl ( Tc = 12. 8 K, 0. 3 kbar) and Br( Tc = 11. 6 K) salts

    SciTech Connect

    Wang, H.H.; Carlson, K.D.; Geiser, U.; Kini, A.M.; Schultz, A.J.; Williams, J.M.; Montgomery, L.K.; Kwok, W.K.; Welp, U.; Vandervoort, K.G.; Boryschuk, S.J.; Strieby Crouch, A.V.; Kommers, J.M.; Watkins, D.M. ); Schirber, J.E.; Overmyer, D.L. ); Jung, D.; Novoa, J.J.; Whangbo, M.H. )

    1990-01-01

    The syntheses, structures, selected physical properties, and band electronic structures of three copper (I) dicyanamide halide salts of bis(ethylenedithio)tetrathiafulvalene ({kappa}-(ET){sub 2}Cu(N(CN){sub 2})X, where X = Cl, Br, and I) are discussed. X-ray crystallographic studies demonstrate that the three derivatives are isostructural. The bromide salt is an ambient pressure superconductor with an inductive onset at 11.6 K and a resistive onset at 12.5 K. {kappa}-(ET){sub 2}Cu(N(CN){sub 2})Cl exhibits the highest reported superconducting transition temperature ({Tc} = 12.8 K, 0.3 kbar) for an organic superconductor, once a semiconductor-semiconductor transition (42 K) is suppressed. The application of GE varnish or Apiezon N grease to crystals of {kappa}-(ET){sub 2}Cu(N(CN){sub 2})Cl provides sufficient stress to induce superconductivity at ambient pressure.'' Crystals of the iodide remain metallic to {approximately}150 K, where they become weakly semiconductive. No sign of superconductivity was detected at pressures (hydrostatic and shearing) up to 5.2 kbar and at temperatures as low as 1.1 K. The band electronic structures of the three salts are essentially identical. The differences in superconducting properties are explained in terms of differences in lattice softness, which are strongly influenced by short C-H{hor ellipsis}donor and C-H{hor ellipsis}anion contacts. 17 refs., 2 figs.

  19. High Coulombic efficiency aluminum-ion battery using an AlCl3-urea ionic liquid analog electrolyte.

    PubMed

    Angell, Michael; Pan, Chun-Jern; Rong, Youmin; Yuan, Chunze; Lin, Meng-Chang; Hwang, Bing-Joe; Dai, Hongjie

    2017-01-31

    In recent years, impressive advances in harvesting renewable energy have led to a pressing demand for the complimentary energy storage technology. Here, a high Coulombic efficiency (∼99.7%) Al battery is developed using earth-abundant aluminum as the anode, graphite as the cathode, and a cheap ionic liquid analog electrolyte made from a mixture of AlCl3 and urea in a 1.3:1 molar ratio. The battery displays discharge voltage plateaus around 1.9 and 1.5 V (average discharge = 1.73 V) and yielded a specific cathode capacity of ∼73 mAh g(-1) at a current density of 100 mA g(-1) (∼1.4 C). High Coulombic efficiency over a range of charge-discharge rates and stability over ∼150-200 cycles was easily demonstrated. In situ Raman spectroscopy clearly showed chloroaluminate anion intercalation/deintercalation of graphite (positive electrode) during charge-discharge and suggested the formation of a stage 2 graphite intercalation compound when fully charged. Raman spectroscopy and NMR suggested the existence of AlCl4(-), Al2Cl7(-) anions and [AlCl2·(urea)n](+) cations in the AlCl3/urea electrolyte when an excess of AlCl3 was present. Aluminum deposition therefore proceeded through two pathways, one involving Al2Cl7(-) anions and the other involving [AlCl2·(urea)n](+) cations. This battery is a promising prospect for a future high-performance, low-cost energy storage device.

  20. The crystalline phases present in carbon cathodes of discharged Li/SOCl2-LiAlCl4 cells

    NASA Astrophysics Data System (ADS)

    Williams, R. M.; Surampudi, S.; Bankston, C. P.

    1989-05-01

    The X-ray diffraction patterns of 100 percent discharged Schawinigan black cathodes from Li/SOCl2-LiAlCl4 cells were obtained using a high resolution Guinier camera. The previous assignments of the diffraction lines to Li2O2 and rhombohedral sulfur are all found to be incorrect; all sharp Bragg diffraction lines not assignable to anhydrous LiCl can be assigned to LiCl.H2O.

  1. Synthesis of polypropylene from 1-propanol using AlCl3 Ziegler-Natta catalyst

    NASA Astrophysics Data System (ADS)

    Salmahaminati, Jumina

    2016-11-01

    Synthesis of polypropylene from 1-propanol had been done. Polypropylene was synthesized via dehydration of 1-propanol using sulfuric acid catalyst followed with polymerization using AlCl3 catalyst to produce polypropylene. Structural characterization of products was done by means of IR spectrometer and the molecular weight of polypropylene was measured by viscometri Ubbelohde. Polymerization reaction by dehydration of 1-propanol using sulfuric acid catalyst produced propylene and followed with polymerization gave polypropylene in the molecular weight of 3900 g/mol with repetitive units of 93.

  2. New ionic liquids based on complexation of dipropylsulfide and AlCl3 for electrochodeposition of aluminum

    DOE PAGES

    Fang, Youxing; Jiang, Xueguang; Dai, Sheng; ...

    2015-01-01

    A new kind of ionic liquid based on complexation of dipropyl sulfide (DPS) and AlCl3 has been prepared. The equivalent concentration of AlCl3 in the ionic liquid is as high as 2.3 M. More importantly, it is highly fluidic and exhibits an ambient ionic conductivity of 1.25 x 10-4 S cm-1. This new ionic liquid can be successfully used as an electrolyte for electrodeposition of aluminum.

  3. Electrical, dielectric and electrochemical measurements of bulk aluminum phthalocyanine chloride (AlPcCl)

    NASA Astrophysics Data System (ADS)

    Soliman, I. M.; El-Nahass, M. M.; Mansour, Y.

    2016-01-01

    AC conductivity and the related dielectric properties of bulk aluminum phthalocyanine chloride (AlPcCl) have been studied over a temperature range (303-403 K) and frequency range (42-106 Hz). The universal power law σac (ω)=Aωs has been used to investigate dependence of AC conductivity on frequency. The variation of the frequency exponent (s) with temperature was analyzed in terms of different conduction mechanisms; the predominant conduction mechanism was found to be the correlated barrier hopping (CBH) model. The barrier height was calculated by using (CBH) model, it was found to be 1.41 eV. Dependence of σac (ω) on temperature refers to a linear increase with increasing temperature at different frequencies. The density of states N (EF) was calculated to be equal 4.11×1019 cm-3 using Elliott model. It has been found that AC activation energy decreases with increasing frequency. Dielectric values were analyzed using complex permittivity and complex electric modulus for bulk AlPcCl at different temperatures. The obtained value of HOMO-LUMO energy gap was found to be 1.48 eV.

  4. Determination of molecular stopping cross section of 12C, 16O, 28Si, 35Cl, 58Ni, 79Br, and 127I in silicon nitride

    NASA Astrophysics Data System (ADS)

    Barradas, N. P.; Bergmaier, A.; Mizohata, K.; Msimanga, M.; Räisänen, J.; Sajavaara, T.; Simon, A.

    2015-10-01

    Silicon nitride is a technologically important material in a range of applications due to a combination of important properties. Ion beam analysis techniques, and in particular, heavy ion elastic recoil detection analysis can be used to determine the stoichiometry of silicon nitride films, which often deviates from the ideal Si3N4, as well as the content of impurities such as hydrogen, even in the presence of other materials or in a matrix containing heavier elements. Accurate quantification of IBA results depends on the basic data used in the data analysis. Quantitative depth profiling relies on the knowledge of the stopping power cross sections of the materials studied for the ions involved, which in the case of HI-ERDA is both the primary beam, and the recoiled species. We measured the stopping cross section of 12C, 16O, 28Si, 35Cl, 58Ni, 79Br, and 127I in a well-characterised silicon nitride membrane. The measurements were made by independent groups utilising different experimental setups and methods. In some cases there is extensive overlap of the energy range in different experiments, allowing a comparison of the different results. The four independent data sets reported in this work are in excellent agreement with each other, in the cases where similar energy ranges were measured. On the other hand, the data are in most cases higher than calculations made with the interpolative schemes SRIM and MSTAR together with the Bragg rule. Better agreement is found with MSTAR in some of the cases studied. This work is a significant extension of the heavy ion stopping power data base for silicon nitride.

  5. Analyses of the tilde{A}-tilde{X} Electronic Transitions of the CH{_2}XOO{\\cdot}(X = i, Br, Cl) Radicals

    NASA Astrophysics Data System (ADS)

    Kline, Neal; Huang, Meng; Miller, Terry A.

    2016-06-01

    Cavity ringdown, near-infrared spectra have been previously observed following the photolysis of the dihalomethanes(CH{_2}XI, X = I, Br, Cl) in the presence of O{_2} and N{_2}. In last year's Symposium, we presented evidence that all the spectra could be attributed to the tilde{A}-tilde{X} electronic transition of the appropriate CH{_2}XOO{\\cdot} radical. We now present detailed analyses of these spectra. Similar spectral features have been observed for all radicals. The first strong transitions are located around 6800 cm{-1}, and are assigned as associated with the origin. Other strong transitions are observed about 800 cm{-1} blue of the origin, and have a multiple-peak structure similar to the corresponding origin bands. These bands are assigned to be the OO stretch of the tilde{A}-tilde{X} electronic transitions, which are typically strong in the spectra of peroxy radicals, based on electronic structure calculations that provide vibrational frequencies and Franck-Condon factors. One-dimensional calculations of the internal torsion mode are applied to specifically explain the multiple-peak features in both the origin and OO stretch region as series of transitions including sequence bands and other hot bands from the vibrationally excited states of the low-frequency torsion mode in the tilde{X} state, which are significantly populated at room temperature. Additional bands can be assigned to fundamentals or combination bands of various other tilde{A} state modes. N. D. Kline, M. Huang, T. A. Miller, P. Lolur, R. Dawes, FD05, 70th International Symposium of Molecular Spectroscopy(2015)

  6. F+ tunable laser activity and interaction of atomic halogens (F, Cl and Br) at the low coordinated surface sites of SrOAb initio and DFT calculations.

    PubMed

    Shalabi, Ahmed S

    2002-10-01

    The twofold potential of F+ color centers at the low coordinated surfaces of SrO for providing tunable laser activity and adsorption properties for atomic halogens (F, Cl and Br) has been investigated using ab initio electronic structure calculations. SrO clusters of variable sizes were embedded in simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces and the nearest neighbor ions to F+ were allowed to relax to equilibrium. Based on Stokes shifted optical transition bands and horizontal shifts along the configuration coordinate diagrams, the F+ laser activity was found to decrease as the coordination number of the surface ions decreases from 5 (flat) to 4 (edge) to 3 (corner). An attempt has been made to explain this result in terms of Madelung potentials and optical-optical conversion efficiencies. All relaxed excited states are deep below the conduction bands of the perfect ground states, implying that F+ is a laser-suitable defect. The most laser active flat surface is the least probable for relaxed excited state orientational destruction of F+. The excited state at the edge has the highest energy, implying exciton (energy) transfer to the flat and edge sites. F+ relaxation and defect-formation energies increase with increasing surface coordination number. The Glasner-Tompkins relation between the fundamental optical absorption of F+ in solids and the fundamental absorption of the host crystals can be generalized to include the low coordinated surfaces of SrO. The F+ color center changes the nature of halogen-surface interaction (adsorption energies) from physical adsorption to chemical adsorption. The halogen-surface interactions increase with increasing electronegativity of the halogen. The calculated adsorption energies can be explained in terms of surface electrostatic potentials, and the covalent spin pairing mechanism plays a dominant role in determining adsorbate-substrate interactions.

  7. Coordination-directed one-dimensional coordination polymers generated from a new oxadiazole bridging ligand and HgX2 (X=Cl, Br and I).

    PubMed

    Yang, Rui; Ma, Jian Ping; Huang, Ru Qi; Dong, Yu Bin

    2011-06-01

    A new 1,3,4-oxadiazole bridging bent organic ligand, 2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole, C(28)H(24)N(4)O(3), L, has been used to create three novel one-dimensional isomorphic coordination polymers, viz. catena-poly[[[dichloridomercury(II)]-μ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgCl(2)(C(28)H(24)N(4)O(3))]·CH(3)OH}(n), catena-poly[[[dibromidomercury(II)]-μ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgBr(2)(C(28)H(24)N(4)O(3))]·CH(3)OH}(n), and catena-poly[[[diiodidomercury(II)]-μ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgI(2)(C(28)H(24)N(4)O(3))]·CH(3)OH}(n). The free L ligand itself adopts a cis conformation, with the two terminal pyridine rings and the central oxadiazole ring almost coplanar [dihedral angles = 5.994 (7) and 9.560 (6)°]. In the Hg(II) complexes, however, one of the flexible pyridylmethyl arms of ligand L is markedly bent and helical chains are obtained. The Hg(II) atom lies in a distorted tetrahedral geometry defined by two pyridine N-atom donors from two L ligands and two halide ligands. The helical chains stack together via interchain π-π interactions that expand the dimensionality of the structure from one to two. The methanol solvent molecules link to the complex polymers through O-H···N and O-H···O hydrogen bonds.

  8. A LiAl/Cl2 battery with a four-component alkali-metal chloride electrolyte

    NASA Astrophysics Data System (ADS)

    Thomas, Daniel L.; Bennion, Douglas N.

    1989-12-01

    A LiAl/Cl2 cell operating at 280 C was investigated. This electrolyte is a mixture of LiC, KCl, RbCl, and CsCl with a eutectic melting point of 258 C. The positive electrode is a gas-diffusion electrode formed by coating one side of a porous carbon electrode with PTCE. The limiting discharge current of the cell was controlled by solid-state diffusion of Li in the LiAl alloy. Polarization of Cl2 electrode was caused by the low cross-sectional area of the electrolyte film compared with the pore cross-sectional area. Deactivation of the positive electrode was caused by impurities, such as Cu(+), in the electrolyte. Mathematical models of the negative and positive electrodes in a LiAl/Cl2 cell with a gas diffusion Cl2 electrode have been formulated. A thin film gas diffusion electrode model was used for the positive electrode, while solid-state diffusion of Li-in alpha-LiAl was assumed to limit the negative electrode and the cell current. Comparison of the experimental results with the model indicate that the diffusivity of Li in alpha-LiAl is of the order of 10 to the -12 sq cm/sec.

  9. COMBINING COSMOGENIC BE, C, AL AND CL - Quantifying depth of glacial erosion and timing of deglaciation

    NASA Astrophysics Data System (ADS)

    Wirsig, C.; Ivy-Ochs, S.; Akcar, N.; Alfimov, V.; Kämpfer, C.; Schlüchter, C.

    2012-04-01

    Over the course of the next years, we are aiming to combine signals of cosmogenic Be-10, C-14, Al-26 and Cl-36 to constrain depth and rate of glacial erosion at several study sites in the Alps and to determine the timing of local deglaciation. Within this suite of nuclides, the system of Be is the best understood. It is routinely used and often combined with Al for various applications in Quaternary Geology, i.e. dating rock avalanches. Cl-36 is an important addition due to its unique depth profile: complicated production pathways cause the maximum concentration not to form at the top of the rock, but at a depth of some centimetres [1]. Furthermore, extending the suite by in-situ produced C-14 is crucial. Its short half-live enables the detection of brief periods of ice coverage that could not be noticed in the other nuclides. Measurement of in-situ produced C-14 in bedrock is not trivial, but has been achieved with reliable results [2]. Concentration-depth profiles for all of these nuclides can be modelled for diverse scenarios of past ice coverage. If the local Quaternary history is known independently, (glacial) erosion rates can be determined. As a first study site, Grueben glacier in the Grimsel region was chosen. The area was recently mapped in detail by C. Kämpfer allowing to draw robust conclusions based on field observations. Here we will present and discuss exposure ages of four bedrock samples taken to be analysed this winter for a first assessment of the local situation and to identify promising sites for intense examination in the future. [1] Alfimov and Ivy-Ochs, Quat. Geochr. 4, 2009 [2] Hippe et. al., Quat. Geochr. 4, 2009

  10. Photoelectron spectroscopy of aqueous solutions: Streaming potentials of NaX (X = Cl, Br, and I) solutions and electron binding energies of liquid water and X{sup −}

    SciTech Connect

    Kurahashi, Naoya; Horio, Takuya; Suzuki, Toshinori; Karashima, Shutaro; Suzuki, Yoshi-Ichi; Tang, Ying; Abulimiti, Bumaliya; Ogi, Yoshihiro; Oura, Masaki

    2014-05-07

    The streaming potentials of liquid beams of aqueous NaCl, NaBr, and NaI solutions are measured using soft X-ray, He(I), and laser multiphoton ionization photoelectron spectroscopy. Gaseous molecules are ionized in the vicinity of liquid beams and the photoelectron energy shifts are measured as a function of the distance between the ionization point and the liquid beam. The streaming potentials change their polarity with concentration of electrolytes, from which the singular points of concentration eliminating the streaming potentials are determined. The streaming currents measured in air also vanish at these concentrations. The electron binding energies of liquid water and I{sup −}, Br{sup −}, and Cl{sup −} anions are revisited and determined more accurately than in previous studies.

  11. Conformational Properties of 1-Halogenated-1-Silacyclohexanes, C5H10SiHX (X = Cl, Br, I): Gas Electron Diffraction, Low-Temperature NMR, Temperature-Dependent Raman Spectroscopy, and Quantum-Chemical Calculations†

    PubMed Central

    2013-01-01

    The molecular structures of axial and equatorial conformers of cyclo-C5H10SiHX (X = Cl, Br, I) as well as the thermodynamic equilibrium between these species was investigated by means of gas electron diffraction, dynamic nuclear magnetic resonance, temperature-dependent Raman spectroscopy, and quantum-chemical calculations applying CCSD(T), MP2, and DFT methods. According to the experimental and calculated results, all three compounds exist as a mixture of two chair conformers of the six-membered ring. The two chair forms of Cs symmetry differ in the axial or equatorial position of the X atom. In all cases, the axial conformer is preferred over the equatorial one. When the experimental uncertainties are taken into account, all of the experimental and theoretical results for the conformational energy (Eaxial – Eequatorial) fit into a remarkably narrow range of −0.50 ± 0.15 kcal mol–1. It was found by NBO analysis that the axial conformers are unfavorable in terms of steric energy and conjugation effects and that they are stabilized mainly by electrostatic interactions. The conformational energies for C6H11X and cyclo-C5H10SiHX (X = F, Cl, Br, I, At) were compared using CCSD(T) calculations. In both series, fluorine is predicted to have a lower conformational preference (cyclohexane equatorial, silacyclohexane axial) than Cl, Br, and I. It is predicted that astatine would behave very similarly to Cl, Br, and I within each series. PMID:24353364

  12. Two-dimensional H2O-Cl2 and H2O-Br2 potential surfaces: an ab initio study of ground and valence excited electronic states.

    PubMed

    Hernandez-Lamoneda, Ramón; Rosas, Victor Hugo Uc; Uruchurtu, Margarita I Bernal; Halberstadt, Nadine; Janda, Kenneth C

    2008-01-10

    All electron ab initio calculations for the interaction of H2O with Cl2 and Br2 are reported for the ground state and the lowest triplet and singlet Pi excited states as a function of both the X-X and O-X bond lengths (X = Cl or Br). For the ground state and lowest triplet state, the calculations are performed with the coupled cluster singles, doubles, and perturbative triple excitation level of correlation using an augmented triple-zeta basis set. For the 1Pi state the multireference average quadratic coupled cluster technique was employed. For several points on the potential, the calculations were repeated with the augmented quadruple-zeta basis set. The ground-state well depths were found to be 917 and 1,183 cm-1 for Cl2 and Br2, respectively, with the triple-zeta basis set, and they increased to 982 and 1,273 cm-1 for the quadruple-zeta basis set. At the geometry of the ground-state minimum, the lowest energy state corresponding to the unperturbed 1Pi states of the halogens increases in energy by 637 and 733 cm-1, respectively, relative to the ground-state dissociation limit of the H2O-X2 complex. Adding the attractive ground-state interaction energy to that of the repulsive excited state predicts a blue-shift, relative to that of the free halogen molecules, of approximately 1,600 cm-1 for H2O-Cl2 and approximately 2,000 cm-1 for H2O-Br2. These vertical blue-shifts for the dimers are greater than the shift of the band maximum upon solvation of either halogen in liquid water.

  13. High-Altitude Aircraft and Balloon-Borne Observations of OH, HO2, ClO, BrO, NO2, ClONO2, ClOOCl, H2O, and O3 in Earth's Stratosphere

    NASA Technical Reports Server (NTRS)

    Anderson, James G.

    1999-01-01

    Using observations from balloon-borne instruments and aircraft-borne instruments the investigation arrived at the following developments.: (1) Determination of the dominant catalytic cycles that destroy ozone in the lower stratosphere; (2) The partial derivatives of the rate limiting steps are observables in the lower stratosphere; (3) Recognition that the "Low NOx" condition is the regime that holds the greatest potential for misjudgement of Ozone loss rates; (4) Mapping of the Bromine radical contribution to the ozone destruction rate in the lower stratosphere; (5) Observation of OH, HO2 and ClO in the plume of the Concorde SST in the stratosphere; (6) Determination of the diurnal behavior of OH in the lower stratosphere; (7) Observed OH and H02 in the Troposphere and the interrelationship between Ozone and OH, HO2, CO and NO; (8) Analysis of the Catalytic Production of Ozone and Reactions that Couple OH and H02 in the Troposphere; (9) The continuing development of the understanding of the Tropopause temperatures, water vapor mixing ratios, and vertical advection and the mixing in of mid-latitude air; (10) Performed Multiple Tracer Analyses as a diagnostic of water vapor intrusion into the "Middle World" (i.e., the lowermost stratsophere); (11) Flight testing of a new instrument for the In Situ detection of ClON02 from the ER-2; (12) Laser induced fluorescence detection of NO2. There is included an in depth discussion of each of these developments and observations.

  14. Crystal growth and crystal structures of six novel phases in the Mn/As/O/Cl(Br) system, as well as magnetic properties of α-Mn3(AsO4)2

    NASA Astrophysics Data System (ADS)

    Weil, Matthias; Kremer, Reinhard K.

    2017-01-01

    Chemical vapour transport reactions (900 °C → 820 °C, Cl2 or Br2 as transport agent) of in situ formed Mn3(AsO4)2 yielded the orthoarsenates(V) α-Mn3(AsO4)2 and β-Mn3(AsO4)2 as well as the oxoarsenate(V) halide compounds Mn7(AsO4)4Cl2, Mn11(AsO4)7Cl, Mn11(AsO4)7Br and Mn5(AsO4)3Cl. The crystal structures of all six phases were determined from single crystal X-ray diffraction data. The crystal structures of α-and β-Mn3(AsO4)2 are isotypic with the corresponding phosphate phases γ- and α-Mn3(PO4)2, respectively, and are reported here for the first time. A comparative discussion with other structures of general composition M3(AsO4)2 (М = Mg; divalent first-row transition metal) is given. The unique crystal structures of Mn7(AsO4)4Cl2 and that of the two isotypic Mn11(AsO4)7X (X = Cl, Br) structures are composed of two [MnO5] polyhedra, two [MnO4Cl2] polyhedra (one with site symmetry 1 bar), two AsO4 tetrahedra, and one [MnO5] polyhedron, three [MnO6] octahedra (one with site symmetry.m.), one [MnO4X], one [MnO5X] polyhedron and four AsO4 tetrahedra, respectively. The various polyhedra of the three arsenate(V) halides are condensed into three-dimensional framework structures by corner- and edge-sharing. Mn5(AsO4)3Cl adopts the chloroapatite structure. The magnetic and thermal properties of pure polycrystalline samples of a-Mn3(AsO4)2 were investigated in more detail. The magnetic susceptibility proves all Mn atoms to be in the oxidation state +2 yielding an effective magnetic moment per Mn atom of 5.9 μB. Long-range antiferromagnetic ordering is observed below 8.2 K consistent with the negative Curie-Weiss temperature of -50 K derived from the high temperature susceptibility data. Chemical vapour transport reactions of in situ formed Mn3(AsO4)2 using Cl2 or Br2 as transport agents led to crystal growth of six phases structurally determined for the first time: α-Mn3(AsO4)2, β-Mn3(AsO4)2, Mn7(AsO4)4Cl2, Mn11(AsO4)7Cl, Mn11(AsO4)7Br and Mn5(AsO4)3Cl.

  15. Laser cooling of the AlCl molecule with a three-electronic-level theoretical model

    NASA Astrophysics Data System (ADS)

    Wan, Mingjie; Yuan, Di; Jin, Chengguo; Wang, Fanhou; Yang, Yujie; Yu, You; Shao, Juxiang

    2016-07-01

    Feasibility of laser-cooling AlCl molecule is investigated using ab initio quantum chemistry. Potential energy curves, permanent dipole moments, and transition dipole moments for the X1Σ+, a3Π, and A1Π states are studied based on multi-reference configuration interaction plus Davidson corrections (MRCI+Q) method with ACVQZ basis set, spin-orbit coupling effects are considered at the MRCI+Q level. Highly diagonally distributed Franck-Condon factors (f00 = 0.9988 and f11 = 0.9970) and branching ratios (R00 = 0.9965, R01 = 2.85 × 10-3, R02 = 6.35 × 10-4, and R03 = 2.05 × 10-6) for the A 1 Π 1 ( ν ' = 0 ) → X 1 Σ0 + + ( ν ″ = 0 ) transition are determined. A sufficiently radiative lifetime τ (A1Π1) = 4.99 ns is predicted for rapid laser cooling. The proposed cooling wavelength is deep in the ultraviolet region at λ00 = 261.75 nm. Total emission rates for the a 3 Π 0 + → X 1 Σ0 + + , a 3 Π 1 → X 1 Σ0 + + , A1Π1 → a3Π0+, and A1Π1 → a3Π1 transitions are particularly small (˜10 s-1-650 s-1). The calculated vibrational branching loss ratio to the intermediate a3Π0+ and a3Π1 states can be negligible. The results imply the probability of laser cooling AlCl molecule with three-electronic-level.

  16. Synergistic effect and mechanisms of compound bioflocculant and AlCl3 salts on enhancing Chlorella regularis harvesting.

    PubMed

    Zhang, Chaofan; Wang, Xiansheng; Wang, Yao; Li, Yunbao; Zhou, Dandan; Jia, Yanwu

    2016-06-01

    The high energy input required for harvesting microalgae means that commercial production of microalgal biodiesel is economically unfeasible. In this study, we investigated the flocculation efficiency and synergistic mechanisms of novel coupled flocculants, AlCl3 and compound bioflocculants (CBF), to overcome this difficulty. AlCl3 flocculation was found to be very sensitive to pH, and flocculation efficiency increased from 55 to 95 % when pH increased from 4 to 10. CBF was environmental friendly, less reliant on pH, but had a relatively low flocculation of 75 % in optimum conditions. The harvesting efficiency of Chlorella regularis can achieve a satisfactory level of 96.77 % even in neutral conditions, with a CBF dosage of 0.26 g/L, AlCl3 dosage of 0.18 g/L, and coagulant aid (CaCl2) dosage of 0.12 g/L. Interestingly, compared with the use of single flocculant, the dosage of CBF, AlCl3, and coagulant aid (CaCl2) were reduced by about 52, 49, and 66 %, respectively. Besides, the aluminum (Al) ion content of the supernatant decreased significantly to a residue of only 0.03 mg/L, therefore meeting the downstream process needs easily. Patching and bridging played key roles in coupled flocculant flocculation, in which AlCl3 mainly carried out the electrical neutralization. This work provides new insight into an efficient, economical, and environmentally friendly protocol for microalgae harvesting.

  17. Evidence for Live Cl-36 in Ca-Al-rich Inclusions from the Ningqiang Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Lin, Y.; Guan, Y.; Leshin, L. A.; Ouyang, Z.; Wang, D.

    2004-01-01

    The short-lived radionuclide Cl-36 decays to either Ar-36 (98.1%, beta(sup -)) or S-36 (1.9%, epsilon and beta(sup +)), with a half life of 3.01 x 10(exp 5) yr. Both the nucleosynthetic and spallation models suggest high initial Cl-36/Cl-35 ratios ((Cl-36/Cl-35)o up to approximately 10(exp -4)) in the early solar system. Previous observed excess Ar-36 in Efremovka matrix has been interpreted to represent a much lower (Cl-36/Cl-35)o ratio of approximately 1 x 10(exp -6). From the observed S-36 excesses in sodalite in calcium aluminum-rich inclusions (CAIs), we report in this study the first direct evidence of the presence of Cl-36 in primitive meteorites. The inferred (Cl-36/Cl-35)o ratios range from approximately 5 x 10(exp -6) to approximately 1 x 10(exp -5).

  18. Transparent CH3NH3SnCl3/Al-ZnO p-n heterojunction diode

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Ansari, Mohd. Zubair; Khare, Neeraj

    2016-05-01

    A p-type Organic inorganic tin chloride (CH3NH3SnCl3) perovskite thin film has been synthesized by solution method. An n-type 1% Al doped ZnO (AZO) film has been deposited on FTO substrate by ultrasonic assisted chemical vapor deposition technique. A transparent CH3NH3SnCl3/AZO p-n heterojunction diode has been fabricated by spin coating technique. CH3NH3SnCl3/AZO p-n heterojunction shows 75% transparency in the visible region. I-V characteristic of CH3NH3SnCl3/AZO p-n heterojunction shows rectifying behavior of the diode. The diode parameters calculated as ideality factor η=2.754 and barrier height V= 0.76 eV. The result demonstrates the potentiality of CH3NH3SnCl3/AZO p-n heterojunction for transparent electronics.

  19. Rotational excitation of AlCl induced by its collision with helium: cross sections and collisional rate coefficients

    NASA Astrophysics Data System (ADS)

    Pamboundom, Mama; Tchakoua, Théophile; Nsangou, Mama

    2016-04-01

    In this work, inelastic rotational collision of AlCl with helium was studied. The CCSD(T) method was used for the computation of an accurate two dimensional potential energy surface (PES). In the calculation of the PES, Al-Cl bond was frozen at the experimental value 4.02678 a0. The aug-cc-pVQZ basis sets of Dunning was used throughout the computational process. This basis was completed with a set of 3s3p2d2f1g bond functions placed at mid-distance between the center of mass of AlCl and He atom for a better description of the van der Waals interaction energy. The PES of AlCl-He was found to have a global minimum at (R=8.65 a0, θ=0 degree), a local minimum at (R=7.45 a0, θ=82 degree) and a saddle point at (R=7.9 a0, θ=56 degree). The depths of the minima were 20.2 cm^{-1} and 19.8 cm^{-1} respectively for θ=0 and 84 degrees. The height of the saddle point with respect to the global minimum was 1.3 cm^{-1}. The PES, the result of an analytical fit, was expanded in terms of Legendre polynomials, then used for the evaluation of state-to-state rotational integral cross sections for the collision of AlCl with He in the close coupling approach. The collisional cross sections for the transitions occurring among the 17 first rotational levels of AlCl were calculated for kinetic energies up to 4000 cm^{-1}. Collisional rate coefficients between these rotational levels were computed for low and moderate kinetic temperatures ranging from 30 to 500 K. A propensity rule that favors odd Δ j transitions was found.

  20. New ionic liquids based on complexation of dipropylsulfide and AlCl3 for electrochodeposition of aluminum

    SciTech Connect

    Fang, Youxing; Jiang, Xueguang; Dai, Sheng; Sun, Xiao-Guang

    2015-01-01

    A new kind of ionic liquid based on complexation of dipropyl sulfide (DPS) and AlCl3 has been prepared. The equivalent concentration of AlCl3 in the ionic liquid is as high as 2.3 M. More importantly, it is highly fluidic and exhibits an ambient ionic conductivity of 1.25 x 10-4 S cm-1. This new ionic liquid can be successfully used as an electrolyte for electrodeposition of aluminum.

  1. A Br Isotopic Study of Australian Arid Playa Lakes and halophyte vegetation as a monitor of Br transport

    NASA Astrophysics Data System (ADS)

    Schaefer, B. F.

    2014-12-01

    Bromine possesses a chemistry broadly comparable to that of Cl and F, however its heavier mass and lower abundance results in slightly different behaviours in geochemical cycling. For example it is disproportionately enriched in sea water with respect to Cl. Br can be considered to be a "hydrophile" element, and hence its behaviour is in governed by that of water. It possesses two isotopes 79Br (50.686%) and 81Br (49.314%). This study has developed new chemical extraction, and most significantly, new mass spectrometric protocols for Br isotopes on silicates, evaporites and waters using N-TIMS methodologies. Existing CF-IRMS methodologies offer internal precision of ~0.3‰ (1SD, [1]), whereas N-TIMS measurements of laboratory HBr and seawater standards produce external reproducibility of <0.07‰ (1SD) over an 18 month period with internal precision typically <0.06‰ (1SD) on single analyses. This study presents the first high precision, N-TIMS isotopic data on playa lake evaporites, recording a >5‰ variation in solar system 81Br/79Br. Also presented is data from the analysis of the halophylic saltbush (sp Atriplex) adjacent to the lakes to constrain biological fractionation of Br isotopes. Variations of ~4‰ are observed between the lakes with a comparable shift for the leaves of the saltbush. [1] Shouaker-Stash et al., Anal. Chem, 77; p4027-4033, 2005.

  2. Structure of the mercury(II) mixed-halide (Br/Cl) complex of 2,2'-(5-tert-butyl-1,3-phenyl-ene)bis-(1-pentyl-1H-benzo[d]imidazole).

    PubMed

    Rani, Varsha; Singh, Harkesh B; Butcher, Ray J

    2017-03-01

    The mercury(II) complex of 2,2'-(5-tert-butyl-1,3-phenyl-ene)bis-(1-pentyl-1H-benz-imidazole), namely catena-poly[[dihalogenido-mercury(II)]-μ-2,2'-(5-tert-butyl-1,3-phenyl-ene)bis-(1-pentyl-1H-benzimidazole)-κ(2)N(3):N(3')], [HgBr1.52Cl0.48(C34H42N4)], 2, has a polymeric structure bridging via the N atoms from the benzimidazole moieties of the ligand. The compound crystallizes in the ortho-rhom-bic space group Pca21 and is a racemic twin [BASF = 0.402 (9)]. The geometry around the Hg(II) atom is distorted tetra-hedral, with the Hg(II) atom coordinated to two N atoms, one Br atom, and a fourth coordination site is occupied by a mixed halide (Br/Cl). For the two ligands in the asymmetric unit, there is disorder with one of the two tert-butyl groups and benzimidazole moieties showing twofold disorder, with occupancy factors of 0.57 (2):0.43 (2) for the tert-butyl group and 0.73 (3):0.27 (3) for the benzimidazole group. In addition, there is threefold disorder for two of the four n-pentyl groups, with occupancy factors of 0.669 (4):0.177 (4):0.154 (4) and 0.662 (4):0.224 (4):0.154 (4), respectively. The mol-ecules form a one-dimensional helical polymer propagating in the b-axis direction. The helices are held together by intra-strand C-H⋯Br and C-H⋯Cl inter-actions. Each strand is further linked by inter-strand C-H⋯Br and C-H⋯Cl inter-actions. In addition, there are weak C-H⋯N inter-strand inter-actions which further stabilize the structural arrangement.

  3. Structure of the mercury(II) mixed-halide (Br/Cl) complex of 2,2′-(5-tert-butyl-1,3-phenyl­ene)bis­(1-pentyl-1H-benzo[d]imidazole)

    PubMed Central

    Rani, Varsha; Singh, Harkesh B.

    2017-01-01

    The mercury(II) complex of 2,2′-(5-tert-butyl-1,3-phenyl­ene)bis­(1-pentyl-1H-benz­imidazole), namely catena-poly[[dihalogenido­mercury(II)]-μ-2,2′-(5-tert-butyl-1,3-phenyl­ene)bis­(1-pentyl-1H-benzimidazole)-κ2 N 3:N 3′], [HgBr1.52Cl0.48(C34H42N4)], 2, has a polymeric structure bridging via the N atoms from the benzimidazole moieties of the ligand. The compound crystallizes in the ortho­rhom­bic space group Pca21 and is a racemic twin [BASF = 0.402 (9)]. The geometry around the HgII atom is distorted tetra­hedral, with the HgII atom coordinated to two N atoms, one Br atom, and a fourth coordination site is occupied by a mixed halide (Br/Cl). For the two ligands in the asymmetric unit, there is disorder with one of the two tert-butyl groups and benzimidazole moieties showing twofold disorder, with occupancy factors of 0.57 (2):0.43 (2) for the tert-butyl group and 0.73 (3):0.27 (3) for the benzimidazole group. In addition, there is threefold disorder for two of the four n-pentyl groups, with occupancy factors of 0.669 (4):0.177 (4):0.154 (4) and 0.662 (4):0.224 (4):0.154 (4), respectively. The mol­ecules form a one-dimensional helical polymer propagating in the b-axis direction. The helices are held together by intra-strand C—H⋯Br and C—H⋯Cl inter­actions. Each strand is further linked by inter-strand C—H⋯Br and C—H⋯Cl inter­actions. In addition, there are weak C—H⋯N inter-strand inter­actions which further stabilize the structural arrangement. PMID:28316824

  4. Using Cl/Br ratios and other indicators to assess potential impacts on groundwater quality from septic systems: A review and examples from principal aquifers in the United States

    USGS Publications Warehouse

    Katz, B.G.; Eberts, S.M.; Kauffman, L.J.

    2011-01-01

    A detailed review was made of chemical indicators used to identify impacts from septic tanks on groundwater quality. Potential impacts from septic tank leachate on groundwater quality were assessed using the mass ratio of chloride-bromide (Cl/Br), concentrations of selected chemical constituents, and ancillary information (land use, census data, well depth, soil characteristics) for wells in principal aquifers of the United States. Chemical data were evaluated from 1848 domestic wells in 19 aquifers, 121 public-supply wells in 6 aquifers, and associated monitoring wells in four aquifers and their overlying hydrogeologic units. Based on previously reported Cl/Br ratios, statistical comparisons between targeted wells (where Cl/Br ratios range from 400 to 1100 and Cl concentrations range from 20 to 100 mg/L) and non-targeted wells indicated that shallow targeted monitoring and domestic wells (0.5. mg/L) shallow groundwater from target domestic wells, relative to non-target wells (1.5. mg/L), corresponded to significantly higher potassium, boron, chloride, dissolved organic carbon, and sulfate concentrations, which may also indicate the influence of septic-tank effluent. Impacts on groundwater quality from septic systems were most evident for the Eastern Glacial Deposits aquifer and the Northern High Plains aquifer that were associated with the number of housing units using septic tanks, high permeability of overlying sediments, mostly oxic conditions, and shallow wells. Overall, little or no influence from septic systems were found for water samples from the deeper public-supply wells.The Cl/Br ratio is a useful first-level screening tool for assessing possible septic tank influence in water from shallow wells (<20 m) with the range of 400-1100. The use of this ratio would be enhanced with information on other chloride sources, temporal variability of chloride and bromide concentrations in shallow groundwater, knowledge of septic-system age and maintenance, and the

  5. Inductively coupled BCl3/Cl2 /Ar plasma etching of Al-rich AlGaN

    SciTech Connect

    Douglas, Erica A.; Sanchez, Carlos A.; Kaplar, Robert J.; Allerman, Andrew A.; Baca, Albert G.

    2016-12-01

    Varying atomic ratios in compound semiconductors is well known to have large effects on the etching properties of the material. The use of thin device barrier layers, down to 25 nm, adds to the fabrication complexity by requiring precise control over etch rates and surface morphology. The effects of bias power and gas ratio of BCl3 to Cl2 for inductively coupled plasma etching of high Al content AlGaN were contrasted with AlN in this study for etch rate, selectivity, and surface morphology. Etch rates were greatly affected by both bias power and gas chemistry. Here we detail the effects of small variations in Al composition for AlGaN and show substantial changes in etch rate with regards to bias power as compared to AlN.

  6. Behavior of Halogen Bonds of the Y-X⋅⋅⋅π Type (X, Y=F, Cl, Br, I) in the Benzene π System, Elucidated by Using a Quantum Theory of Atoms in Molecules Dual-Functional Analysis.

    PubMed

    Sugibayashi, Yuji; Hayashi, Satoko; Nakanishi, Waro

    2016-08-18

    The nature of halogen bonds of the Y-X-✶-π(C6 H6 ) type (X, Y=F, Cl, Br, and I) have been elucidated by using the quantum theory of atoms in molecules (QTAIM) dual-functional analysis (QTAIM-DFA), which we proposed recently. Asterisks (✶) emphasize the presence of bond-critical points (BCPs) in the interactions in question. Total electron energy densities, Hb (rc ), are plotted versus Hb (rc )-Vb (rc )/2 [=(ħ(2) /8m)∇(2) ρb (rc )] for the interactions in QTAIM-DFA, in which Vb (rc ) are potential energy densities at the BCPs. Data for perturbed structures around fully optimized structures were used for the plots, in addition to those of the fully optimized ones. The plots were analyzed by using the polar (R, θ) coordinate for the data of fully optimized structures with (θp , κp ) for those that contained the perturbed structures; θp corresponds to the tangent line of the plot and κp is the curvature. Whereas (R, θ) corresponds to the static nature, (θp , κp ) represents the dynamic nature of the interactions. All interactions in Y-X-✶-π(C6 H6 ) are classified by pure closed-shell interactions and characterized to have vdW nature, except for Y-I-✶-π(C6 H6 ) (Y=F, Cl, Br) and F-Br-✶-π(C6 H6 ), which have typical hydrogen-bond nature without covalency. I-I-✶-π(C6 H6 ) has a borderline nature between the two. Y-F-✶-π(C6 H6 ) (Y=Br, I) were optimized as bent forms, in which Y-✶-π interactions were detected. The Y-✶-π interactions in the bent forms are predicted to be substantially weaker than those in the linear F-Y-✶-π(C6 H6 ) forms.

  7. Electrochemistry in ultrahigh vacuum: underpotential deposition of Al on polycrystalline W and Au from room temperature AlCl(3)/1-ethyl-3-methylimidazolium chloride melts.

    PubMed

    Johnston, Matthew; Lee, Jae-Joon; Chottiner, Gary S; Miller, Barry; Tsuda, Tetsuya; Hussey, Charles L; Scherson, Daniel A

    2005-06-09

    The voltammetric characteristics of polycrystalline Au and W electrodes cleaned (thermal annealing at 1100 K) and characterized (Auger electron spectroscopy) in ultrahigh vacuum (UHV) have been examined in ultrapure AlCl(3)/1-ethyl-3-methylimidazolium chloride (EtMeImCl) melts in UHV. These experiments were performed using a custom-designed transfer system that allows for the all-Al electrochemical cell to be filled with EtMeImCl in an auxiliary UHV chamber and later transferred under UHV to the main UHV chamber that houses the Auger electron spectrometer. The results obtained for the underpotential (UPD) and bulk deposition of Al on Au were found to be very similar to those reported in the literature for measurements carried out under 1 atm of an inert gas in a glovebox. For the far more reactive W surfaces, voltammetric features ascribed to the stripping of underpotential-deposited Al could be observed following a single scan from 1.0 V vs Al(3+)/Al to a potential negative enough for bulk deposition of Al to ensue. This behavior is unlike that reported in the literature for experiments performed in a glovebox, which required either extensive potential cycling in the Al bulk deposition and stripping region or excursions to potentials positive enough for chlorine evolution to ensue for Al UPD features to be clearly discerned. These observations open new prospects for fundamental electrochemical studies of well-characterized, highly reactive metals, including single crystals, in a variety of low vapor pressure ionic liquids.

  8. The binding of platinum hexahalides (Cl, Br and I) to hen egg-white lysozyme and the chemical transformation of the PtI{sub 6} octahedral complex to a PtI{sub 3} moiety bound to His15

    SciTech Connect

    Tanley, Simon W. M.; Starkey, Laurina-Victoria; Lamplough, Lucinda; Kaenket, Surasek; Helliwell, John R.

    2014-08-29

    The platinum hexahalides have an octahedral arrangement of six halogen atoms bound to a Pt centre, thus having an octahedral shape that could prove to be useful in interpreting poor electron-density maps. In a detailed characterization, PtI{sub 6} chemically transformed to a square-planar PtI{sub 3} complex bound to the N{sup δ} atom of His15 of HEWL was also observed, which was not observed for PtBr{sub 6} or PtCl{sub 6}. This study examines the binding and chemical stability of the platinum hexahalides K{sub 2}PtCl{sub 6}, K{sub 2}PtBr{sub 6} and K{sub 2}PtI{sub 6} when soaked into pre-grown hen egg-white lysozyme (HEWL) crystals as the protein host. Direct comparison of the iodo complex with the chloro and bromo complexes shows that the iodo complex is partly chemically transformed to a square-planar PtI{sub 3} complex bound to the N{sup δ} atom of His15, a chemical behaviour that is not exhibited by the chloro or bromo complexes. Each complex does, however, bind to HEWL in its octahedral form either at one site (PtI{sub 6}) or at two sites (PtBr{sub 6} and PtCl{sub 6}). As heavy-atom derivatives of a protein, the octahedral shape of the hexahalides could be helpful in cases of difficult-to-interpret electron-density maps as they would be recognisable ‘objects’.

  9. Synthesis, characterization and sorption properties of functionalized Cr-MIL-101-X (X=-F, -Cl, -Br, -CH3, -C6H4, -F2, -(CH3)2) materials

    NASA Astrophysics Data System (ADS)

    Buragohain, Amlan; Couck, Sarah; Van Der Voort, Pascal; Denayer, Joeri F. M.; Biswas, Shyam

    2016-06-01

    Four existing and three new functionalized chromium terephthalates having MIL-101 topology and denoted as Cr-MIL-101-X (existing ones with X=-F, 1-F; -Cl, 2-Cl; -Br, 3-Br; -CH3, 4-CH3; new ones with X=-C6H4, 5-C6H4; -F2, 6-F2, -(CH3)2, 7-(CH3)2) were synthesized under hydrothermal conditions. All the materials except 5-C6H4 could be prepared by a general synthetic route, in which the mixtures of CrO3, H2BDC-X (BDC=1,4-benzenedicarboxylate) linkers, conc. HCl and water with a molar ratio of 1:1:3.9:222.2 were reacted at 180 °C for 144 h. Compared to the 144 h of synthesis time, three of the compounds, namely 1-Cl, 2-Br and 5-C6H4, could be prepared in much shorter reaction times (12-18 h at 180-210 °C). The materials possess high thermal stability up to 270-300 °C in an air atmosphere. The activated compounds exhibit significant porosity (SBET range: 1273-2135 m2 g-1). At 0 °C and 1 bar, the CO2 adsorption capacities of the compounds fall in the 1.7-2.9 mmol g-1 range. Compounds 1-F and 6-F2 showed enhanced CO2 uptake values compared to parent Cr-MIL-101. The benzene adsorption capacities of the compounds lie in the range of 66.2-139.5 molecules per unit cell at 50 °C and p/p0=0.35. The increased benzene uptake value of 1-F compared to un-functionalized Cr-MIL-101 and 4-CH3 suggests that the fluorination has induced more hydrophobicity in Cr-MIL-101 as compared to the methylation.

  10. Effect of CaO on retention of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn, W and Pb in bottom ashes from fluidized-bed coal combustion power station.

    PubMed

    Bartoňová, Lucie; Klika, Zdeněk

    2014-07-01

    This work was conducted to evaluate whether Ca-bearing additives used during coal combustion can also help with the retention of some other elements. This work was focused on the evaluation of bottom ashes collected during four full-scale combustion tests at an operating thermal fluidized-bed power station. Bottom ashes were preferred to fly ashes for the study to avoid interference from condensation processes usually occurring in the post-combustion zone. This work focused on the behaviors of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn, W, and Pb. Strong positive correlations with CaO content in bottom ashes were observed (for all four combustion tests) for S, As, Cl and Br (R=0.917-0.999). Strong inverse proportionality was calculated between the contents of Pb, Zn, Ni, Cr and Mn and CaO, so these elements showed association to materials other than Ca-bearing compounds (e.g., to aluminosilicates, organic matter, etc.). Somewhat unclear behaviors were observed for W, Cu, and V. Their correlation coefficients were evaluated as statistically "not significant", i.e., these elements were not thought to be significantly associated with CaO. It was also discovered that major enrichment of CaO in the finest bottom ash fractions could be advantageously used for simple separation of elements strongly associated with these fractions, mainly S and As, but also Cl or Br. Removal of 5% of the finest ash particles brings about a decrease in As concentration down to 77%-80% of its original bulk ash content, which can be conveniently used e.g., when high As content complicates further ash utilization.

  11. Erosion rate study at the Allchar deposit (Macedonia) based on radioactive and stable cosmogenic nuclides (26Al, 36Cl, 3He, and 21Ne)

    NASA Astrophysics Data System (ADS)

    Pavićević, M. K.; Cvetković, V.; Niedermann, S.; Pejović, V.; Amthauer, G.; Boev, B.; Bosch, F.; Aničin, I.; Henning, W. F.

    2016-02-01

    This paper focuses on constraining the erosion rate in the area of the Allchar Sb-As-Tl-Au deposit (Macedonia). It contains the largest known reserves of lorandite (TlAsS2), which is essential for the LORanditeEXperiment (LOREX), aimed at determining the long-term solar neutrino flux. Because the erosion history of the Allchar area is crucial for the success of LOREX, we applied terrestrial in situ cosmogenic nuclides including both radioactive (26Al and 36Cl) and stable (3He and 21Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying 26Al, 36Cl, and 21Ne for around 85% of the entire sample collection, with resulting erosion rates varying from several tens of m/Ma to ˜165 m/Ma. The samples from four locations (L-8 CD, L1b/R, L1c/R, and L-4/ADR) give erosion rates between 300 and 400 m/Ma. Although these localities reveal remarkably higher values, which may be explained by burial events that occurred in part of Allchar, the erosion rate estimates mostly in the range between 50 and 100 m/Ma. This range further enables us to estimate the vertical erosion rate values for the two main ore bodies Crven Dol and Centralni Deo. We also estimate that the lower and upper limits of average paleo-depths for the ore body Centralni Deo from 4.3 Ma to the present are 250-290 and 750-790 m, respectively, whereas the upper limit of paleo-depth for the ore body Crven Dol over the same geological age is 860 m. The estimated paleo-depth values allow estimating the relative contributions of 205Pb derived from pp-neutrino and fast cosmic-ray muons, respectively, which is an important prerequisite for the LOREX experiment.

  12. Erosion rate study at the Allchar deposit (Macedonia) based on radioactive and stable cosmogenic nuclides ((26)Al, (36)Cl, (3)He, and (21)Ne).

    PubMed

    Pavićević, M K; Cvetković, V; Niedermann, S; Pejović, V; Amthauer, G; Boev, B; Bosch, F; Aničin, I; Henning, W F

    2016-02-01

    This paper focuses on constraining the erosion rate in the area of the Allchar Sb-As-Tl-Au deposit (Macedonia). It contains the largest known reserves of lorandite (TlAsS2), which is essential for the LORanditeEXperiment (LOREX), aimed at determining the long-term solar neutrino flux. Because the erosion history of the Allchar area is crucial for the success of LOREX, we applied terrestrial in situ cosmogenic nuclides including both radioactive ((26)Al and (36)Cl) and stable ((3)He and (21)Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying (26)Al, (36)Cl, and (21)Ne for around 85% of the entire sample collection, with resulting erosion rates varying from several tens of m/Ma to ∼165 m/Ma. The samples from four locations (L-8 CD, L1b/R, L1c/R, and L-4/ADR) give erosion rates between 300 and 400 m/Ma. Although these localities reveal remarkably higher values, which may be explained by burial events that occurred in part of Allchar, the erosion rate estimates mostly in the range between 50 and 100 m/Ma. This range further enables us to estimate the vertical erosion rate values for the two main ore bodies Crven Dol and Centralni Deo. We also estimate that the lower and upper limits of average paleo-depths for the ore body Centralni Deo from 4.3 Ma to the present are 250-290 and 750-790 m, respectively, whereas the upper limit of paleo-depth for the ore body Crven Dol over the same geological age is 860 m. The estimated paleo-depth values allow estimating the relative contributions of (205)Pb derived from pp-neutrino and fast cosmic-ray muons, respectively, which is an important prerequisite for the LOREX experiment.

  13. Erosion rate study at the Allchar deposit (Macedonia) based on radioactive and stable cosmogenic nuclides (26 Al, 36 Cl, 3 He, and 21 Ne)

    PubMed Central

    Cvetković, V.; Niedermann, S.; Pejović, V.; Amthauer, G.; Boev, B.; Bosch, F.; Aničin, I.; Henning, W. F.

    2016-01-01

    Abstract This paper focuses on constraining the erosion rate in the area of the Allchar Sb‐As‐Tl‐Au deposit (Macedonia). It contains the largest known reserves of lorandite (TlAsS2), which is essential for the LORanditeEXperiment (LOREX), aimed at determining the long‐term solar neutrino flux. Because the erosion history of the Allchar area is crucial for the success of LOREX, we applied terrestrial in situ cosmogenic nuclides including both radioactive (26Al and 36Cl) and stable (3He and 21Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying 26Al, 36Cl, and 21Ne for around 85% of the entire sample collection, with resulting erosion rates varying from several tens of m/Ma to ∼165 m/Ma. The samples from four locations (L‐8 CD, L1b/R, L1c/R, and L‐4/ADR) give erosion rates between 300 and 400 m/Ma. Although these localities reveal remarkably higher values, which may be explained by burial events that occurred in part of Allchar, the erosion rate estimates mostly in the range between 50 and 100 m/Ma. This range further enables us to estimate the vertical erosion rate values for the two main ore bodies Crven Dol and Centralni Deo. We also estimate that the lower and upper limits of average paleo‐depths for the ore body Centralni Deo from 4.3 Ma to the present are 250–290 and 750–790 m, respectively, whereas the upper limit of paleo‐depth for the ore body Crven Dol over the same geological age is 860 m. The estimated paleo‐depth values allow estimating the relative contributions of 205Pb derived from pp‐neutrino and fast cosmic‐ray muons, respectively, which is an important prerequisite for the LOREX experiment. PMID:27587984

  14. High-frequency magnetic oscillations of the organic metal θ-(ET)4ZnBr4(C6H4Cl2) in pulsed magnetic field of up to 81 T

    NASA Astrophysics Data System (ADS)

    Béard, J.; Billette, J.; Suleiman, M.; Frings, P.; Knafo, W.; Scheerer, G. W.; Duc, F.; Vignolles, D.; Nardone, M.; Zitouni, A.; Delescluse, P.; Lagarrigue, J.-M.; Giquel, F.; Griffe, B.; Bruyant, N.; Nicolin, J.-P.; Rikken, G. L. J. A.; Lyubovskii, R. B.; Shilov, G. V.; Zhilyaeva, E. I.; Lyubovskaya, R. N.; Audouard, A.

    2012-09-01

    De Haas-van Alphen oscillations of the organic metal θ-(ET)4ZnBr4(C6H4Cl2) are studied in pulsed magnetic fields up to 81 T. The long decay time of the pulse allows determining reliable field-dependent amplitudes of Fourier components with frequencies up to several kiloteslas. The Fourier spectrum is in agreement with the model of a linear chain of coupled orbits. In this model, all the observed frequencies are linear combinations of the frequency linked to the basic orbit α and to the magnetic-breakdown orbit β.

  15. The effect of particle size on the electrical conductivity of CuCl (Al2O3) composites

    NASA Technical Reports Server (NTRS)

    Chang, M. R.-W.; Shahi, K.; Wagner, J. B., Jr.

    1984-01-01

    The conductivity of CuCl containing Al2O3 of 0.06, 0.3, 1, 3, 8, and 15 micron sized particles was measured between 25 and 390 C. Conductivity was enhanced for the 0.06 and 0.3 sized Al2O3 particles for temperatures below approximately 250 C. The maximum enhancement occurred at 10 m/o of 0.06 micron Al2O3 at 25 C. Uncertain degrees of agglomeration as well as the grain size of the matrix were found to be significant.

  16. Identification of mixed bromidochloridotellurate anions in disordered crystal structures of (bdmim)2[TeX2Y4] (X, Y=Br, Cl; bdmim=1-butyl-2,3-dimethylimidazolium) by combined application of Raman spectroscopy and solid-state DFT calculations.

    PubMed

    Närhi, Sari M; Kutuniva, Johanna; Lajunen, Marja K; Lahtinen, Manu K; Tuononen, Heikki M; Karttunen, Antti J; Oilunkaniemi, Raija; Laitinen, Risto S

    2014-01-03

    The discrete mixed [TeBrxCl6-x](2-) anions in their disordered crystal structures have been identified by using the phases prepared by the reaction of 1-butyl-2,3-dimethylimidazolium halogenides (bdmim)X with tellurium tetrahalogenides TeX4 (X=Cl, Br) as examples. Homoleptic (bdmim)2[TeX6] [X=Cl (1), Br (2)] and mixed (bdmim)2[TeBr2Cl4] (3), and (bdmim)2[TeBr4Cl2] (4) are formed depending on the choice of the reagents, and their crystal structures have been determined by single-crystal X-ray diffraction. The coordination environments of tellurium in all hexahalogenidotellurates are almost octahedral. Because of the crystallographic disorder, the mixed [TeBr2Cl4](2-) and [TeBr4Cl2](2-) anions in 3 and 4 cannot be identified in their crystal structures. Pawley refinement of the X-ray powder diffraction patterns of 1-4 indicates the presence of single phases in all four products. The solid state Raman spectra of 1-4 were assigned with help of DFT calculations that were performed both for the discrete anions in vacuum and for the complete crystal structures employing periodic boundary conditions. The fundamental vibrations of the homoleptic [TeX6](2-) (X=Cl, Br) anions could be well reproduced by the solid-state DFT computations and enabled a complete assignment of the Raman spectra. While the presence of cis-isomers in both [TeBr2Cl4](2-) and [TeBr4Cl2](2-) could be inferred by the computed fundamental vibrations, that of trans-isomers among the reaction products is, however, also possible. The pathway of the formation of [TeX4Y2](2-) isomers from TeX4 and Y(-) (X, Y=Cl, Br) was also explored by DFT calculations both in vacuum and in solution and indicated that both reactions afforded 80 mol% of cis-isomers and 20 mol% of trans-isomers.

  17. Cl, P2O5, U and Br associated with mineral separates from a low and a high Ti mare basalt

    NASA Technical Reports Server (NTRS)

    Jovanovic, S.; Reed, G. W., Jr.

    1980-01-01

    Low Ti basalt 12040 and high Ti basalt 75055 have approximately the same Cl/P2O5 ratio; the Cl is that remaining after a hot water leach. Pyroxene, plagioclase and ilmenite minerals separated from the basalts also tend to have this same Cl/P2O5 ratio. This is evidence that these major minerals do not control the ratio since Cl and P would not be expected to partition to the same extent into each mineral. Olivine appears to be a special case. It is proposed that the grains measured contained inclusions with leachable and P2O5-related Cl. Dilute acid leaches of whole rock and separated minerals have the same or nearly the same Cl/P2O5 ratios as the residual samples. Apatite and whitlockite were probably the phases leached. They must be constituents of the mesostasis and are present as microminerals or coatings on major mineral grains. The acid leach results imply little or no partition of Cl and P2O5 into major minerals.

  18. Electron attachment and detachment: C{sub 6}F{sub 5}Cl, C{sub 6}F{sub 5}Br, and C{sub 6}F{sub 5}I and the electron affinity of C{sub 6}F{sub 5}Cl

    SciTech Connect

    Miller, Thomas M.; Viggiano, A.A.

    2005-01-01

    Measurements are reported of rate constants for electron attachment to C{sub 6}F{sub 5}X (X=Cl,Br,I) and thermal electron detachment from C{sub 6}F{sub 5}Cl{sup -} over the temperature range 300-550 K in 133 Pa of He gas in a flowing-afterglow Langmuir-probe apparatus. This is the first case we know of where the parent anion has sufficiently low electron detachment energy that detachment (from C{sub 6}F{sub 5}Cl{sup -} in this case) has been observed in competition with a channel for dissociative electron attachment yielding a thermally stable anion (here, Cl{sup -}). Because of this competition, it is shown that a simple mass spectrometric determination of the product branching fractions at long times will lead to erroneous results at elevated temperatures. The electron density profiles provide evidence for a new plasma decay process involving the detaching and nondetaching anions trapped in the space charge field of the positive ions. Electron attachment rate constants were found to be 1.0x10{sup -7}, 1.1x10{sup -7}, and 2.0x10{sup -7} cm{sup 3} s{sup -1}, at 300 K, for C{sub 6}F{sub 5}Cl, C{sub 6}F{sub 5}Br, and C{sub 6}F{sub 5}I, respectively, estimated accurate to {+-}25% except for C{sub 6}F{sub 5}I, where there is {+-}30% uncertainty. Rate constants for C{sub 6}F{sub 5}Cl changed little over our temperature range, while those for C{sub 6}F{sub 5}Br, and C{sub 6}F{sub 5}I increased with temperature. Electron detachment occurred only for C{sub 6}F{sub 5}Cl{sup -} in our temperature range. Detachment rate constants were immeasurable at room temperature but approached 4000 s{sup -1} at 550 K. From these data the electron affinity (EA) for C{sub 6}F{sub 5}Cl was determined, EA (C{sub 6}F{sub 5}Cl)=0.75{+-}0.08 eV. G3(MP2) calculations (based on Moeller-Plesset perturbation theory) were carried out for the neutral and anion and yielded EA(C{sub 6}F{sub 5}Cl)=0.728 eV.

  19. Physical chemistry of molten-salt batteries. Final report, October 1, 1981-September 30, 1982. LiCl precipitation from LiCl-KCl anolyte in porous Li-Al electrodes

    SciTech Connect

    Vallet, C.E.; Heatherly, D.E.; Heatherly, L. Jr.; Braunstein, J.

    1983-05-01

    Composition gradients such as those predicted to occur during discharge of porous Li-Al negative electrodes of Li/S batteries with LiCl-KCl eutectic electrolyte were generated and measured in the LiCl-KCl anolyte of an electrolysis cell with Li-Al electrodes. LiCl precipitation during electrolysis was observed by two-dimensional scanning of electrolyte composition in the front part of quenched porous Li-Al anode sections using SEM/EDX. The distribution of sites of increased or decreased LiCl concentration, LiCl saturation and precipitation was mapped. Cathodic regions were observed near the cell walls. Preliminary results of analysis by Auger spectroscopy confirm LiCl precipitation in the porous anode.

  20. Synthesis, structural and optical characterization of APbX{sub 3} (A=methylammonium, dimethylammonium, trimethylammonium; X=I, Br, Cl) hybrid organic-inorganic materials

    SciTech Connect

    Mancini, Alessandro; Quadrelli, Paolo; Amoroso, Giuseppe; Milanese, Chiara; Boiocchi, Massimo; Sironi, Angelo; Patrini, Maddalena; Guizzetti, Giorgio; Malavasi, Lorenzo

    2016-08-15

    In this paper we report the synthesis, the crystal structure and the optical response of APbX{sub 3} (A=MA, DMA, and TMA; X=I, Br) hybrid organic-inorganic materials including some new phases. We observe that as the cation group increases in size, the optical absorption edge shifts to higher energies with energy steps which are systematic and independent on the anion. A linear correlation between the optical bad gap and the tolerance factor has been shown for the series of samples investigated. - Graphical abstract: The crystal structure and the optical response of the two series of hybrid organic-inorganic materials APbX{sub 3} (A=MA, DMA, and TMA; X=I, Br), which include some new phases, are reported. A dependence of crystal structure and band-gap with tolerance factor is shown. Display Omitted - Highlights: • DMAPbI{sub 3}, TMAPbI{sub 3} and TMAPbBr{sub 3} are reported as new hybrid organic-inorganic compounds. • Crystal structure and optical properties as a function of the number of methyl groups are provided. • Correlation between structure and optical properties are given as a function of tolerance factor.

  1. New amide-chloride phases in the Li-Al-N-H-Cl system: formation and hydrogen storage behaviour.

    PubMed

    Fernández Albanesi, L; Garroni, S; Enzo, S; Gennari, F C

    2016-04-07

    New amide-chloride phases were successfully synthesized by mechanical milling of the LiNH2-AlCl3 mixture at a molar ratio of 1 : 0.11 and further heating at 150 °C under argon (0.1 MPa) or under hydrogen pressure (0.7 MPa). Powder X-ray diffraction measurements as a function of milling time increase revealed that the milling of the LiNH2-0.11AlCl3 mixture results in the formation of a FCC solid solution with an excess of LiNH2. Subsequent heating of the LiNH2-0.11AlCl3 sample ball milled for 5 hours at 150 °C under argon or under hydrogen induces the appearance of an amide-chloride phase isostructural with cubic Li4(NH2)3Cl. This Li-Al-N-H-Cl phase transforms progressively into the trigonal phase after prolonged heating at 300 °C under hydrogen pressure. The thermal behaviour of the amide-chloride without and with LiH addition displays dissimilar decomposition pathways. The decomposition of amide-chloride alone involves the formation of ammonia and hydrogen from 120 to 300 °C. Conversely, the amide-chloride material in the presence of LiH only releases hydrogen avoiding the emission of ammonia. The resultant material is able to be rehydrogenated under moderate conditions (300 °C, 0.7 MPa H2), providing a new reversible hydrogen storage system.

  2. A new reaction mode of germanium-silicon bond formation: insertion reactions of H₂GeLiF with SiH₃X (X = F, Cl, Br).

    PubMed

    Yan, Bingfei; Li, Wenzuo; Xiao, Cuiping; Li, Qingzhong; Cheng, Jianbo

    2013-10-01

    A combined density functional and ab initio quantum chemical study of the insertion reactions of the germylenoid H2GeLiF with SiH3X (X = F, Cl, Br) was carried out. The geometries of all the stationary points of the reactions were optimized using the DFT B3LYP method and then the QCISD method was used to calculate the single-point energies. The theoretical calculations indicated that along the potential energy surface, there were one precursor complex (Q), one transition state (TS), and one intermediate (IM) which connected the reactants and the products. The calculated barrier heights relative to the respective precursors are 102.26 (X = F), 95.28 (X = Cl), and 84.42 (X = Br) kJ mol(-1) for the three different insertion reactions, respectively, indicating the insertion reactions should occur easily according to the following order: SiH3-Br > SiH3-Cl > SiH3-F under the same situation. The solvent effects on the insertion reactions were also calculated and it was found that the larger the dielectric constant, the easier the insertion reactions. The elucidations of the mechanism of these insertion reactions provided a new reaction model of germanium-silicon bond formation.

  3. Ab initio calculations on potential energy curves and radiative lifetimes for the band systems A(2)Π-X(2)Σ(+) of magnesium monohalides MgX (X=F, Cl, Br, I).

    PubMed

    Wu, Dong-lan; Tan, Bin; Qin, Jiu-ying; Wan, Hui-jun; Xie, An-dong; Yan, Bing; Ding, Da-jun

    2015-11-05

    Ab initio calculations on potential energy curves (PECs), spectroscopic constants, transition dipole moments, radiative transition probabilities and lifetimes for the ground state (X(2)Σ(+)) and the first excited state (A(2)Π) of MgX (X=F, Cl, Br, I) molecules are determined by high-level internally contracted multi-reference configuration interaction (ic-MRCI) method. In order to improve the calculation, the Davidson modification (+Q) and scalar relativistic correction are included. The present results show that most of spectroscopic constants are in accordance with the measurements, the equilibrium internuclear distance Re increases while the other spectroscopic constants reduce along with the increasing of the atomic number of the halogen from F to I. Diagonal vibrational transitions are found to be dominant for the A(2)Π→X(2)Σ(+) system of MgX molecules. The corresponding radiative lifetimes of ν'=0 are computed to be 7.24, 9.98, 18.94 and 22.72 ns for MgF, MgCl, MgBr, and MgI, respectively. The calculated result of MgF molecule is in good agreement with the recent theoretical result of 7.16 ns, with a small relative error percent of 1.11%.

  4. Communication: Probing the entrance channels of the X + CH{sub 4}{yields} HX + CH{sub 3} (X = F, Cl, Br, I) reactions via photodetachment of X{sup -}-CH{sub 4}

    SciTech Connect

    Cheng Min; Feng Yuan; Du Yikui; Zhu Qihe; Zheng Weijun; Czako, Gabor; Bowman, Joel M.

    2011-05-21

    The entrance channel potentials of the prototypical polyatomic reaction family X + CH{sub 4}{yields} HX + CH{sub 3} (X = F, Cl, Br, I) are investigated using anion photoelectron spectroscopy and high-level ab initio electronic structure computations. The pre-reactive van der Waals (vdW) wells of these reactions are probed for X = Cl, Br, I by photodetachment spectra of the corresponding X{sup -}-CH{sub 4} anion complex. For F-CH{sub 4}, a spin-orbit splitting ({approx}1310 cm{sup -1}) much larger than that of the F atom (404 cm{sup -1}) was observed, in good agreement with theory. This showed that in the case of the F-CH{sub 4} system the vertical transition from the anion ground state to the neutral potentials accesses a region between the vdW valley and transition state of the early-barrier F + CH{sub 4} reaction. The doublet splittings observed in the other halogen complexes are close to the isolated atomic spin-orbit splittings, also in agreement with theory.

  5. High-Altitude Aircraft and Balloon-Borne Observations of OH, HO2, ClO, BrO, NO2, ClONO2, ClOOCl, H2O, and O3 in Earth`s Stratosphere. Progress report, 1 January-31 December 1995

    SciTech Connect

    Anderson, J.G.

    1996-02-01

    Research executed over calendar year 1995 focused on three primary objectives. The first is the dissection of free radical catalytic cycles. The objective is to determine both the mechanisms for ozone loss in the lower stratosphere, by establishing the hierarchy of rate limiting steps in the nitrogen, halogen, and hydrogen cycles, and to determine the response of the stratosphere to changing levels of NO(sub x), aerosols, etc., by directly observing the partial derivatives of the constituent concentrations. Observations are made from the NASA ER-2 aircraft. The second is to incorporate fast-response water vapor measurements into the ER-2 payload, to obtain high spatial resolution data on water vapor. This is a particularly powerful technique for diagnosing dynamical behavior of the stratosphere when combined with the rapid time-response CO2 observations available on the ER-2. The third objective is the development of a new instrument designed for the ER-2 superpod, which will observe ClONO2 in situ for the first time, and also will observe ClO, BrO, and NO2 simultaneously. The authors present the progress made in each category.

  6. Investigation by Mössbauer spectroscopy of Sn redox transformations during H2/O2 titration on Pt/Al2O3Sn-Cl and Pt/Al2O3SnIn-Cl naphtha reforming catalysts

    NASA Astrophysics Data System (ADS)

    Jahel, Ali; Avenier, Priscilla; Lacombe, Sylvie; Olivier-Fourcade, Josette; Jumas, Jean-Claude

    2010-03-01

    Bimetallic Pt/Al2O3Sn-Cl and trimetallic Pt/Al2O3SnIn-Cl catalysts were characterized by H2/O2 double titration and 119Sn Mössbauer spectroscopy. The addition of Sn or both Sn and In to the monometallic Pt/Al2O3-Cl catalyst leads to an increase in the volume of chemisorbed O2 at each titration. For bimetallic and trimetallic catalysts the increase in the Pt dispersion, calculated from the second oxygen titre, abnormally surpasses the barrier of 100%. Characterization of samples obtained after each step of the H2/O2 titration sequence using 119Sn Mössbauer spectroscopy allowed to follow the redox transformations of Sn species suspected of contributing to O2 consumption. 119Sn Mössbauer spectra show that after reduction unalloyed metalic Sn and PtSn alloy phases are formed in bi- and trimetallic catalysts respectively. These metallic phases are oxidized upon the first oxygen titre into the so-called PtxSn(O) oxometalic phases. The index calculated from this titre thus expresses the Pt-Sn bimetallic character and is called the bimetallicity index (BMI). These latter phases further undergo reduction and regeneration (oxidation) upon the second O2 titre and thus contribute to the calculated Pt dispersion as well.

  7. Nuclear Magnetic Resonance Reveals Disordered Level-Crossing Physics in the Bose-Glass Regime of the Br-Doped Ni(Cl_{1-x}Br_{x})_{2}-4SC(NH_{2})_{2} Compound at a High Magnetic Field.

    PubMed

    Orlova, Anna; Blinder, Rémi; Kermarrec, Edwin; Dupont, Maxime; Laflorencie, Nicolas; Capponi, Sylvain; Mayaffre, Hadrien; Berthier, Claude; Paduan-Filho, Armando; Horvatić, Mladen

    2017-02-10

    By measuring the nuclear magnetic resonance (NMR) T_{1}^{-1} relaxation rate in the Br (bond) doped DTN compound, Ni(Cl_{1-x}Br_{x})_{2}-4SC(NH_{2})_{2}(DTNX), we show that the low-energy spin dynamics of its high magnetic field "Bose-glass" regime is dominated by a strong peak of spin fluctuations found at the nearly doping-independent position H^{*}≅13.6  T. From its temperature and field dependence, we conclude that this corresponds to a level crossing of the energy levels related to the doping-induced impurity states. Observation of the local NMR signal from the spin adjacent to the doped Br allowed us to fully characterize this impurity state. We have thus quantified a microscopic theoretical model that paves the way to better understanding of the Bose-glass physics in DTNX, as revealed in the related theoretical study [M. Dupont, S. Capponi, and N. Laflorencie, Phys. Rev. Lett. 118, 067204 (2017).PRLTAO0031-900710.1103/PhysRevLett.118.067204].

  8. Excited State Processes for Aqueous Rh(NH3)5Cl(2+) and Rh(NH3)5Br(2+).

    DTIC Science & Technology

    1981-04-10

    white precipitate of Rh(NH3)5(H20)) Br3 was collected and dried overnight at 110-0 C. The resulting yellow product was recrystallized from water/HClO4 to...aquation. In all cases, product concentrations were corrected for the usually small degree of dark or thermal reaction. Pulsed Laser Experiments. The...direct photochemical production . According to Palmer and Harris [16] the reaction Rh(NH 3)5(OH) 2+ + C02(aq) = Rh(NH 3)5(Co3) + + H+ occurs with a rate

  9. Synthesis, structural and optical characterization of APbX3 (A=methylammonium, dimethylammonium, trimethylammonium; X=I, Br, Cl) hybrid organic-inorganic materials

    NASA Astrophysics Data System (ADS)

    Mancini, Alessandro; Quadrelli, Paolo; Amoroso, Giuseppe; Milanese, Chiara; Boiocchi, Massimo; Sironi, Angelo; Patrini, Maddalena; Guizzetti, Giorgio; Malavasi, Lorenzo

    2016-08-01

    In this paper we report the synthesis, the crystal structure and the optical response of APbX3 (A=MA, DMA, and TMA; X=I, Br) hybrid organic-inorganic materials including some new phases. We observe that as the cation group increases in size, the optical absorption edge shifts to higher energies with energy steps which are systematic and independent on the anion. A linear correlation between the optical bad gap and the tolerance factor has been shown for the series of samples investigated.

  10. Treatment of electrochemical cell components with lithium tetrachloroaluminate (LiAlCl.sub.4) to promote electrolyte wetting

    DOEpatents

    Eberhart, James G.; Battles, James E.

    1980-01-01

    Electrochemical cell components such as interelectrode separators, retaining screens and current collectors are contacted with lithium tetrachloroaluminate prior to contact with molten electrolytic salt to improve electrolyte wetting. The LiAlCl.sub.4 can be applied in powdered, molten or solution form but, since this material has a lower melting point than the electrolytic salt used in high-temperature cells, the powdered LiAlCl.sub.4 forms a molten flux prior to contact by the molten electrolyte when both materials are initially provided in solid form. Components of materials such as boron nitride and other materials which are difficult to wet with molten salts are advantageously treated by this process.

  11. Preparation of Al-La Master Alloy by Thermite Reaction in NaF-NaCl-KCl Molten Salt

    NASA Astrophysics Data System (ADS)

    Jang, Poknam; Li, Hyonmo; Kim, Wenjae; Wang, Zhaowen; Liu, Fengguo

    2015-05-01

    A NaF-NaCl-KCl ternary system containing La2O3 was investigated for the preparation of Al-La master alloy by the thermite reaction method. The solubility of La2O3 in NaF-NaCl-KCl molten salt was determined by the method of isothermal solution saturation. Inductively coupled plasma-optical emission spectroscopy and x-ray diffraction (XRD) analyses were used to consider the content of La2O3 in molten salt and the supernatant composition of molten salt after dissolution of La2O3, respectively. The results showed that the content of NaF had a positive influence on the solubility of La2O3 in NaF-NaCl-KCl molten salts, and the solubility of La2O3 could reach 8.71 wt.% in molten salts of 50 wt.%NaF-50 wt.% (44 wt.%NaCl + 56 wt.%KCl). The XRD pattern of cooling molten salt indicated the formation of LaOF in molten salt, which was probably obtained by the reaction between NaF and La2O3. The kinetic study showed that the thermite reaction was in accord with a first-order reaction model. The main influence factors on La content in the Al-La master alloy product, including molten salt composition, amount of Al, concentration of La2O3, stirring, reduction time and temperature, were investigated by single-factor experimentation. The content of La in the Al-La master alloy could be reached to 10.1 wt.%.

  12. Selective growth of GaAs and GaAlAs by Cl-assisted OMVPE at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Azoulay, R.; Dugrand, L.; Izrael, A.; Rao, E. V. K.; Mellet, R.; Pougnet, A. M.

    1992-03-01

    Selective epitaxy of GaAs is generally obtained at low pressure, when the diffusion length of the active species over the dielectric mask is large enough. Another way is to use an organochloride as a precursor, which suppresses the deposition over the dielectric. This method is also used at reduced pressure. In this work, we have obtained selective area epitaxy of GaAs and GaAIAs for a wide range of aluminium composition by adding a controlled flow of AsCl3 during a conventional OMVPE growth at atmospheric pressure. This method is called Cl-assisted OMVPE. When no AsCl3 is used, a finely structured polycrystal is deposited on the mask. When AsCl3 is introduced into the reactor, with otherwise the same growth conditions, complete selectivity was obtained over a 100 μm wide Si3N4 mask. We have studied the influence of the growth temperature, the TMG/ AsCl3 and the AsH3/TMG ratios on the growth selectivity. We have also studied the evolution of the limiting planes of the selectively grown ridges with different growth conditions. Finally, on a selectively grown GaAs/GaAlAs double heterostructure, room temperature photoluminescence topography was performed.

  13. Anionic Halomolybdate(III) Chemistry. Tetrahydrofuran Loss from [MoX(3)Y(THF)(2)](-) (X, Y = Cl, Br, I), Preparation and Properties of [Mo(3)X(12)](3)(-) (X = Br, I), and Crystal Structure of the Edge-Sharing Trioctahedral [PPh(4)](3)[Mo(3)I(12)].

    PubMed

    Fettinger, James C.; Gordon, John C.; Mattamana, Sundeep P.; O'Connor, Charles J.; Poli, Rinaldo; Salem, Ghadi

    1996-12-04

    By interaction of MoX(3)(THF)(3) with [Cat]X in THF, the salts [Cat][MoX(4)(THF)(2)] have been synthesized [X = I, Cat = PPh(4), NBu(4), NPr(4), (Ph(3)P)(2)N; X = Br, Cat = NBu(4), PPh(4) (Ph(3)P)(2)N]. Mixed-halide species [MoX(3)Y(THF)(2)](-) (X, Y = Cl, Br, I) have also been generated in solution and investigated by (1)H-NMR. When the tetraiodo, tetrabromo, and mixed bromoiodo salts are dissolved in CH(2)Cl(2), clean loss of all coordinated THF is observed by (1)H-NMR. On the other hand, [MoCl(4)(THF)(2)](-) loses only 1.5 THF/Mo. The salts [Cat](3)[Mo(3)X(12)] (X = Br, I) have been isolated from [Cat][MoX(4)(THF)(2)] or by running the reaction between MoX(3)(THF)(3) and [Cat]X directly in CH(2)Cl(2). The crystal structure of [PPh(4)](3)[Mo(3)I(12)] exhibits a linear face-sharing trioctahedron for the trianion: triclinic, space group P&onemacr;; a = 11.385(2), b = 12.697(3), c = 16.849(2) Å; alpha = 76.65(2), beta = 71.967(12), gamma = 84.56(2) degrees; Z = 1; 431 parameters and 3957 data with I > 2sigma(I). The metal-metal distance is 3.258(2) Å. Structural and magnetic data are consistent with the presence of a metal-metal sigma bond order of (1)/(2) and with the remaining 7 electrons being located in 7 substantially nonbonding orbitals. The ground state of the molecule is predicted to be subject to a Jahn-Teller distortion, which is experimentally apparent from the nature of the thermal ellipsoid of the central Mo atom. The [Mo(3)X(12)](3)(-) ions reacts with phosphines (PMe(3), dppe) to form products of lower nuclearity by rupture of the bridging Mo-X bonds.

  14. Determination of the constants of affinity of FeCl3, CuCl2, and ZnCl2 for a nitrogen-containing organosilane bonded on Al2O3-cellulose acetate hybrid material surface from ethanol solution.

    PubMed

    Lazarin, Angélica M; Landers, Richard; Kholin, Yuriy V; Gushikem, Yoshitaka

    2002-10-01

    This work describes the preparation and characterization of a cellulose acetate fiber coated with Al(2)O(3), resulting in the organic-inorganic hybrid Cel/Al(2)O(3). Furthermore, the hybrid was modified by attaching organofunctional groups by reaction with the precursor reagents (RO)(3)Si(CH(2))(3)L (L=NH(2), NH(CH(2))(2)NH(2), NH(CH(2))(2)NH(CH(2))(2)NH(2), and N(2)C(3)H(3) (imidazole)), resulting in Cel/Al(2)O(3)/Si(CH(2))(3)NH(2) (1), Cel/Al(2)O(3)/Si(CH(2))(3)NH(CH(2))(2)NH(2) (2), Cel/Al(2)O(3)/Si(CH(2))(3)NH(CH(2))(2)NH(CH(2))(2)NH(2) (3), and Cel/Al(2)O(3)/Si(CH(2))(3)N(2)C(3)H(3) (4). The amounts of attached organofunctional groups were (in mmol per gram of the material) 1=1.90, 2=1.89, 3=1.66, and 4=1.35. The isotherms of adsorption of FeCl(3), CuCl(2), and ZnCl(2) by Cel/Al(2)O(3)/Si(CH(2))(3)L from ethanol solutions were obtained at 298 K. Accurate estimates of the specific sorption capacities and the heteregeneous stability constants of the immobilized metal complexes were determined with the aid of several computational procedures. It is shown that the sorptional capacities are much less than the concentrations of the attached organofunctional groups. As all sorption isotherms are fitted properly with the Langmuir isotherm equation, the effects of the energetic heterogeneity and the lateral interactions do not affect the chemisorption equilibria. The heterogeneous stability constants of the immobilized complexes are fairly high, which provides efficient removal of the metal ions from solutions by the hybrid materials.

  15. Static and dynamic magnetic properties of two synthetic francisites Cu3La(SeO3)2O2X (X = Br and Cl)

    NASA Astrophysics Data System (ADS)

    Markina, M. M.; Zakharov, K. V.; Zvereva, E. A.; Denisov, R. S.; Berdonosov, P. S.; Dolgikh, V. A.; Kuznetsova, E. S.; Olenev, A. V.; Vasiliev, A. N.

    2016-11-01

    The crystal structure of clinoatacamite, ideally Cu2(OH)3Cl, has been studied using single-crystal X-ray diffraction and Raman scattering at variable temperature between 150 and 490 K in natural samples with different degrees of Co and Ni substitution. The monoclinic clinoatacamite crystal structure is closely related to the trigonal crystal structures of herbertsmithite, Cu3Zn(OH)6Cl2, and paratacamite, Cu3(Cu, Zn)(OH)6Cl2. Disappearance of clinoatacamite superstructure reflections close to a temperature of 400 K indicates the transition to a trigonal herbertsmithite-type phase in all crystals containing Co and Ni impurities. In these crystals, which are invariably twinned at room temperature, an intermediate phase is observed in the temperature range 360-400 K, which has the trigonal paratacamite crystal structure. Untwinned end-member clinoatacamite directly transforms to the herbertsmithite-type at T c = 445 K. Probability density functions of the oxygen and copper atoms as well as details from the Raman scattering measurements indicate that the interlayer Cu-coordination environment remains locally Jahn-Teller-distorted in the trigonal crystal structures with space group symmetries Roverline{3} and Roverline{3} m and that the transition from monoclinic to trigonal symmetry is driven by the dynamic Jahn-Teller effect.

  16. The stability of sodalite in the system NaAlSiO sub 4 -NaCl

    SciTech Connect

    Sharp, Z.D. ); Helffrich, G.R. ); Bohlen, S.R. ); Essene, E.J. )

    1989-08-01

    The reaction sodalite = {beta}-nepheline + NaCl (s) was reversed in solid-medium apparatus and the reaction sodalite = carnegieite + NaCl (l) was reversed at 1 bar (1,649-1,652 K). The experimental reversals between 923 K and 973 K can be fit with a dP/dT of {minus}11 bar/K, suggesting that the excess entropy for sodalite is present only above 923 K. A phase diagram for the NaAlSiO{sub 4}-NaCl system that is consistent with the measured thermochemical data and the experiments between 973 and 1,650 K can be generated if the 61.7 J/mol{center dot}K entropy contribution is included in the S{sup 0}{sub 298} of sodalite. This entropy contribution must be removed below 973 K for the experiments to fit with calculations. Previously unreported thermodynamic data estimated in this study are {Delta}G{sup 0}{sub 298} for sodalite ({minus}12,697 kJ/mol) and carnegieite (NaAlSiO{sub 4}) ({minus}1,958 kJ/mol), S{sup 0}{sub 298} of carnegieite (129.6 J/mol{center dot}K) and compressibility of NaCl{sub liquid} (V{sup P}{sub 298} (cm{sup 3}) = 31.6{center dot}(1 - 24.7{center dot}10{sup {minus}3}{center dot}P + 800{center dot}10{sup {minus}6}{center dot}P{sup 2}))(T in K; P in kbar). Sodalite is a high-temperature, low-pressure phase, stable well above the solidus in sodic silica-undersaturated magmas enriched in NaCl, and its presence constrains NaCl activities in magmas. Estimates of minimum NaCl (l) activities in the Mont St-Hilaire sodalite syenites are 0.05 at 1,073 K and 0.13 at 1,273 K. Density calculations are consistent with the field observations that sodalite phenocrysts will float in a nepheline syenite liquid. This explains the enrichment of sodalite in the upper levels of the sodalite syenites at Mont St.Hilaire and elsewhere.

  17. Ab initio studies on cyanoacetylenes of astrochemical interest: [Y(Ctbnd C)CN, Y dbnd C2H5, C3H7, C4H9, F, Cl, Br and CN

    NASA Astrophysics Data System (ADS)

    Kodi Ramanah, D.; Surajbali, P.; Rhyman, L.; Alswaidan, I. A.; Fun, H.-K.; Somanah, R.; Ramasami, P.

    2016-01-01

    Theoretical studies were performed on seven potential interstellar and circumstellar substituted cyanoacetylenes, Y(Ctbnd C)CN [Y = C2H5, C3H7, C4H9, F, Cl, Br and CN]. Geometry optimizations were carried out using the DFT/B3LYP, the CCSD and CCSD(T) levels of theory. The cc-pVTZ basis set was used for all atoms. Frequency computations were also carried out at the same level of theory as for the optimization to check the nature of the stationary points. The molecular and spectroscopic parameters of the cyanoacetylenes were computed. An analysis of these parameters is in line with the satisfactory performance of the B3LYP/cc-pVTZ level compared to the golden standard, the CCSD(T) level. The theoretical data reported in this work should facilitate future identifications of these cyanoacetylenes in extraterrestrial locations. Plausible mechanisms for the formation of these molecules have been proposed.

  18. Conformational Isomerism of trans-[Pt(NH2C6H11)2I2] and the Classical Wernerian Chemistry of [Pt(NH2C6H11)4]X2 (X = Cl, Br, I)1

    PubMed Central

    Johnstone, Timothy C.; Lippard, Stephen J.

    2012-01-01

    X-ray crystallographic analysis of the compound trans-[Pt(NH2C6H11)2I2] revealed the presence of two distinct conformers within one crystal lattice. This compound was studied by variable temperature NMR spectroscopy to investigate the dynamic interconversion between these isomers. The results of this investigation were interpreted using physical (CPK) and computational (molecular mechanics and density functional theory) models. The conversion of the salts [Pt(NH2C6H11)4]X2 into trans-[Pt(NH2C6H11)2X2] (X = Cl, Br, I) was also studied and is discussed here with an emphasis on parallels to the work of Alfred Werner. PMID:23554544

  19. A rapid method for the measurement of sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), and Halon 1211 (CF2ClBr) in hydrologic tracer studies

    USGS Publications Warehouse

    Busenberg, Eurybiades; Plummer, L. Niel

    2010-01-01

    A rapid headspace method for the simultaneous laboratory determination of intentionally introduced hydrologic tracers, sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), Halon 1211 (CF2ClBr), and other halocarbons in water and gases is described. The high sensitivity of the procedure allows for introduction of minimal tracer mass (a few grams) into hydrologic systems with a large dynamic range of analytical detection (dilutions to 1:108). Analysis times by gas chromatography with electron capture detector are less than 1 min for SF6; about 2 min for SF6 and SF5CF3; and 4 min for SF6, SF5CF3, and Halon 1211. Many samples can be rapidly collected, preserved in stoppered septum bottles, and analyzed at a later time in the laboratory. Examples are provided showing the effectiveness of the gas tracer test studies in varied hydrogeological settings.

  20. Impact of deformation energy on the hydrogen bonding interactions in gas phase 3-X catechol ⋯ H2O complexes (X = H, F, Cl, Br): The effect of approach of a water molecule

    NASA Astrophysics Data System (ADS)

    Deb, Debojit Kumar; Sarkar, Biplab

    2016-06-01

    The conformations and nature of hydrogen bonding interactions for 3-X catechol ⋯ H2O (X = H, F, Cl, Br) has been investigated by ab initio MP2, CCSD(T), and density functional B3LYP, wB97XD and M06-2X methods. The changes in interaction energies due to deformation of the structures has been studied in detail. The intra- and intermolecular hydrogen bonding interactions due to the different direction of approach of water molecule have been discussed. A detailed natural bond orbital (NBO) analysis and the symmetry-adapted perturbation theory (SAPT) based energy decomposition analysis has been carried out to elucidate interaction strength and properties in these hydrogen bonded systems. The charge transfer percentage (CTP) has been derived which will be universally useful for correlating binding energy, deformation energy and the geometrical parameters such as angles, bond lengths, etc. for other systems as well.

  1. Interplay between halogen bond and lithium bond in MCN-LiCN-XCCH (M = H, Li, and Na; X = Cl, Br, and I) complex: the enhancement of halogen bond by a lithium bond.

    PubMed

    Li, Qingzhong; Li, Ran; Liu, Zhenbo; Li, Wenzuo; Cheng, Jianbo

    2011-11-30

    Quantum chemical calculations have been performed to study the complex of MCN-LiCN-XCCH (M = H, Li, and Na; X = Cl, Br, and I). The aim is to study the cooperative effect between halogen bond and lithium bond. The alkali metal has an enhancing effect on the lithium bond, making it increased by 77 and 94% for the Li and Na, respectively. There is the cooperativity between the lithium bond and halogen bond. The former has a larger enhancing effect on the latter, being in a range of 11.7-29.4%. The effect of cooperativity on the halogen bond is dependent on the type of metal and halogen atoms. The enhancing mechanism has been analyzed in views with the orbital interaction, charge transfer, dipole moment, polarizability, atom charges, and electrostatic potentials. The results show that the electrostatic interaction plays an important role in the enhancement of halogen bond.

  2. Effect of externally applied pressure on the magnetic behavior of Cu{sub 2}Te{sub 2}O{sub 5}(Br{sub x}Cl{sub 1-x}){sub 2}

    SciTech Connect

    Crowe, S. J.; Lees, M. R.; Paul, D. M. K.; Bewely, R. I.; Taylor, J.; McIntyre, G.; Zaharko, O.; Berger, H.

    2006-04-01

    The effect of externally applied pressure on the magnetic behavior of Cu{sub 2}Te{sub 2}O{sub 5}(Br{sub x}Cl{sub 1-x}){sub 2} with x=0, 0.73, and 1, is investigated by a combination of magnetic susceptibility, neutron diffraction, and neutron inelastic scattering measurements. The magnetic transition temperatures of the x=0 and 0.73 compositions are observed to increase linearly with increasing pressure at a rate of 0.23(2) and 0.04(1) K/kbar, respectively. However, the bromide shows contrasting behavior with a large suppression of the transition temperature under pressure, at a rate of -0.95(9) K/kbar. In neutron inelastic scattering measurements of Cu{sub 2}Te{sub 2}O{sub 5}Br{sub 2} under pressure only a small change to the ambient pressure magnetic excitations were observed. A peak in the density of states was seen to shift from {approx}5 meV in ambient pressure to {approx}6 meV under an applied pressure of 11.3 kbar, which was associated with an increase in the overall magnetic coupling strength.

  3. Nuclear Magnetic Resonance Reveals Disordered Level-Crossing Physics in the Bose-Glass Regime of the Br-Doped Ni (Cl1 -xBrx )2-4 SC (NH2 )2 Compound at a High Magnetic Field

    NASA Astrophysics Data System (ADS)

    Orlova, Anna; Blinder, Rémi; Kermarrec, Edwin; Dupont, Maxime; Laflorencie, Nicolas; Capponi, Sylvain; Mayaffre, Hadrien; Berthier, Claude; Paduan-Filho, Armando; Horvatić, Mladen

    2017-02-01

    By measuring the nuclear magnetic resonance (NMR) T1-1 relaxation rate in the Br (bond) doped DTN compound, Ni (Cl1 -xBrx )2-4 SC (NH2 )2(DTN X ) , we show that the low-energy spin dynamics of its high magnetic field "Bose-glass" regime is dominated by a strong peak of spin fluctuations found at the nearly doping-independent position H*≅13.6 T . From its temperature and field dependence, we conclude that this corresponds to a level crossing of the energy levels related to the doping-induced impurity states. Observation of the local NMR signal from the spin adjacent to the doped Br allowed us to fully characterize this impurity state. We have thus quantified a microscopic theoretical model that paves the way to better understanding of the Bose-glass physics in DTN X , as revealed in the related theoretical study [M. Dupont, S. Capponi, and N. Laflorencie, Phys. Rev. Lett. 118, 067204 (2017)., 10.1103/PhysRevLett.118.067204].

  4. Electrochemically conductive treatment of TiO2 nanotube arrays in AlCl3 aqueous solution for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhong, Wenjie; Sang, Shangbin; Liu, Yingying; Wu, Qiumei; Liu, Kaiyu; Liu, Hongtao

    2015-10-01

    Highly ordered TiO2 nanotube arrays (NTAs) with excellent stability and large specific surface area make them competitive using as supercapacitor materials. Improving the conductivity of TiO2 is of great concern for the construction of high-performance supercapacitors. In this work, we developed a novel approach to improve the performance of TiO2 materials, involving the fabrication of Al-doped TiO2 NTAs by a simple electrochemical cathodic polarization treatment in AlCl3 aqueous solution. The prepared Al-doped TiO2 NTAs exhibited excellent electrochemical performances, attributing to the remarkably improved electrical conductivity (i.e., from approx. 10 kΩ to 20 Ω). Further analysis showed that Al3+ ions rather than H+ protons doped into TiO2 lattice cause this high conductivity. A MnO2/Al-TiO2 composite was evaluated by cyclic voltammetry, and achieved the specific capacitance of 544 F g-1, and the Ragone plot of the sample showed a high power density but less reduction of energy density. These results indicate that the MnO2/Al-TiO2 NTAs sample could be served as a promising electrode material for high -performance supercapacitors.

  5. Mutual neutralization of atomic rare-gas cations (Ne{sup +}, Ar{sup +}, Kr{sup +}, Xe{sup +}) with atomic halide anions (Cl{sup −}, Br{sup −}, I{sup −})

    SciTech Connect

    Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, Albert A.; Johnsen, Rainer

    2014-01-28

    We report thermal rate coefficients for 12 reactions of rare gas cations (Ne{sup +}, Ar{sup +}, Kr{sup +}, Xe{sup +}) with halide anions (Cl{sup −}, Br{sup −}, I{sup −}), comprising both mutual neutralization (MN) and transfer ionization. No rate coefficients have been previously reported for these reactions; however, the development of the Variable Electron and Neutral Density Attachment Mass Spectrometry technique makes it possible to measure the difference of the rate coefficients for pairs of parallel reactions in a Flowing Afterglow-Langmuir Probe apparatus. Measurements of 18 such combinations of competing reaction pairs yield an over-determined data set from which a consistent set of rate coefficients of the 12 MN reactions can be deduced. Unlike rate coefficients of MN reactions involving at least one polyatomic ion, which vary by at most a factor of ∼3, those of the atom-atom reactions vary by at least a factor 60 depending on the species. It is found that the rate coefficients involving light rare-gas ions are larger than those for the heavier rare-gas ions, but the opposite trend is observed in the progression from Cl{sup −} to I{sup −}. The largest rate coefficient is 6.5 × 10{sup −8} cm{sup 3} s{sup −1} for Ne{sup +} with I{sup −}. Rate coefficients for Ar{sup +}, Kr{sup +}, and Xe{sup +} reacting with Br{sub 2}{sup −} are also reported.

  6. FT-IR and Raman spectra, ab initio and density functional computations of the vibrational spectra, molecular geometries and atomic charges of uracil and 5-halogenated uracils (5-X-uracils; X=F, Cl, Br, I).

    PubMed

    Singh, J S

    2014-01-03

    Raman (200-4000 cm(-1)) and FT-IR (400-4000 cm(-1)) spectra of uracil and 5-halogenated uracils (5-X-uracils; X=F, Cl, Br, I) have been recorded and analyzed in the range 200-4000 cm(-1). The optimized molecular geometries, atomic polar tensor (APT) charges and vibrational characteristics have been studied theoretically using restricted Hartree-Fock (RHF) and density functional theory (DFT) methods. Ab initio and DFT calculations [using Becke's exchange in conjunction with Lee-Yang-Parr's correlation functional and Becke's three-parameter hybrid method (B3LYP)] were carried out to study the optimized molecular fundamental vibrational frequencies for uracil and 5-halogenated uracils by employing Gaussian-03 program. Gauss View software was used to make the vibrational analysis. Raman and IR spectra have been computed theoretically for the uracil and 5-halogenated molecules. The fundamental vibrational frequencies along with their corresponding intensities in IR and Raman activities and depolarization ratios of the Raman lines have also been calculated using the RHF and DFT methods employing different basis sets. Quantum chemical calculations helped in the reassignments of some fundamental vibrational modes. Most of the B3LYP/6-311++G(**) vibrational frequencies are in excellent agreement with available experimental assignments. The ring breathing and kekule stretching modes are found to lower magnitudes compared to those for uracil which could be due to mass effect of halogen atom in place of the hydrogen atom. The C-X (X=F, Cl, Br, I) stretching frequency is distinctly separated from the CH/NH ring stretching frequencies on the pyrimidine ring. All other bands have also been assigned different fundamentals/overtones/combinations.

  7. Exploring the Reactivity Trends in the E2 and SN2 Reactions of X(-) + CH3CH2Cl (X = F, Cl, Br, HO, HS, HSe, NH2 PH2, AsH2, CH3, SiH3, and GeH3).

    PubMed

    Wu, Xiao-Peng; Sun, Xiao-Ming; Wei, Xi-Guang; Ren, Yi; Wong, Ning-Bew; Li, Wai-Kee

    2009-06-09

    The reactivity order of 12 anions toward ethyl chloride has been investigated by using the G2(+) method, and the competitive E2 and SN2 reactions are discussed and compared. The reactions studied are X(-) + CH3CH2Cl → HX + CH2═CH2 + Cl(-) and X(-) + CH3CH2Cl → CH3CH2X + Cl(-), with X = F, Cl, Br, HO, HS, HSe, NH2 PH2, AsH2, CH3, SiH3, and GeH3. Our results indicate that there is no general and straightforward relationship between the overall barriers and the proton affinity (PA) of X(-); instead, discernible linear correlations only exist for the X's within the same group of the periodic table. Similar correlations are also found with the electronegativity of central atoms in X, deformation energy of the E2 transition state (TS), and the overall enthalpy of reaction. It is revealed that the electronegativity will significantly affect the barrier height, and a more electronegative X will stabilize the E2 and SN2 transition states. Multiple linear regression analysis shows that there is a reasonable linear correlation between E2 (or SN2) overall barriers and the linear combination of PA of X(-) and electronegativity of the central atom.

  8. Generation of oxoiron (IV) tetramesitylporphyrin pi-cation radical complexes by m-CPBA oxidation of ferric tetramesitylporphyrin derivatives in butyronitrile at - 78 degrees C. Evidence for the formation of six-coordinate oxoiron (IV) tetramesitylporphyrin pi-cation radical complexes FeIV = O(tmp*)X (X = Cl-, Br-), by Mössbauer and X-ray absorption spectroscopy.

    PubMed

    Wolter, T; Meyer-Klaucke, W; Müther, M; Mandon, D; Winkler, H; Trautwein, A X; Weiss, R

    2000-01-30

    The generation of six-coordinate oxoiron (IV) tetramesitylporphyrin pi-caption radical complexes by m-CPBA (meta-chloroperbenzoic acid) oxidation of ferric tetramesitylporphyrin derivatives in butyronitrile at - 78 degrees C was investigated. UV-Vis and EPR spectroscopies indicate that the axial ligand present in the ferric starting derivatives is retained in the high-valent iron complexes. Indirect evidence for the formation of six-coordinate oxoiron (IV) tetramesitylporphyrin complexes FeIV = O(tmp*)X (X=Cl-, Br-) by m-CPBA oxidation of FeX(tmp) (X=Cl-, Br-) in butyronitrile at - 78 degrees C was also obtained by Mössbauer spectroscopy. Direct confirmation of the presence of a halide ion as second axial ligand of iron in these high-valent iron species was obtained by X-ray absorption spectroscopy. The EXAFS spectra of the samples obtained by m-CPBA oxidation of FeX(tmp) (X=Cl-, Br-) were refined using two different coordination models including both four porphyrinato-nitrogens and the axial oxo group. The two models include (model I) or exclude (model II) the axial halogen. The statistical tests indicate the presence of a halide ion as second axial ligand of iron in both derivatives. The refinements led to the following bond distances: FeIV=O(tmp*)Cl(3):Fe-O=1.66(1),Fe-Cl=2.39(2) and Fe-Np=1.99(1) A;FeIV=O(tmp*)Br(4):Fe-O=1.65(1),Fe-Br=2.93(2), Fe-Np=2.02(1) A. The lengthening of the Fe-X(X=Cl-, Br-) distances relative to those occurring in the ferric precursor porphyrins is, most probably, related to the strong trans influence of the oxoiron(IV) fragment present in 3 or 4.

  9. Oxidation of elemental mercury vapor over gamma-Al2O3 supported CuCl2 catalyst for mercury emissions control

    SciTech Connect

    Liu, Zhouyang; Liu, Xin; Lee, Joo-Youp; Bolin, Trudy B.

    2015-09-01

    In our previous studies, CuCl2 demonstrated excellent Hg(0) oxidation capability and holds potential for Hg(0) oxidation in coal-fired power plants. In this study, the properties and performances of CuCl2 supported onto gamma-Al2O3 with high surface area were investigated. From various characterization techniques using XPS, XAFS, XRD, TPR, SEM and TGA, the existence of multiple copper species was identified. At low CuCl2 loadings, CuCl2 forms copper aluminate species with gamma-Al2O3 and is inactive for Hg(0) oxidation. At high loadings, amorphous CuCl2 forms onto the gamma-Al2O3 surface, working as a redox catalyst for Hg(0) oxidation by consuming Cl to be converted into CuCl and then being regenerated back into CuCl2 in the presence of O-2 and HCl gases. The 10%(wt) CuCl2/gamma-Al2O3 catalyst showed excellent Hg(0) oxidation performance and SO2 resistance at 140 degrees C under simulated flue gas conditions containing 6%(v) O-2 and 10 ppmv HCl. The oxidized Hg(0) in the form of HgCl2 has a high solubility in water and can be easily captured by other air pollution control systems such as wet scrubbers in coal-fired power plants. The CuCl2/gamma-Al2O3 catalyst can be used as a low temperature Hg(0) oxidation catalyst. (C) 2015 Elsevier B.V. All rights reserved.

  10. Thermodynamic properties of antiferromagnetic ordered states of π -d interacting systems of κ -(BETS) 2Fe X4(X =Br ,Cl )

    NASA Astrophysics Data System (ADS)

    Fukuoka, Shuhei; Yamashita, Satoshi; Nakazawa, Yasuhiro; Yamamoto, Takashi; Fujiwara, Hideki; Shirahata, Takashi; Takahashi, Kazuko

    2016-06-01

    The results are presented for systematic heat capacity measurements of π-d interacting systems of κ -(BETS) 2Fe Br4 and κ -(BETS) 2FeC l4 [BETS = bis(ethylenedithio)tetraselenafulvalene] performed under in-plane magnetic fields. We observed sharp thermal anomalies at 2.47 K for κ -(BETS) 2FeB r4 and at 0.47 K for κ -(BETS) 2FeC l4 at 0 T that are associated with antiferromagnetic transitions of the 3 d electrons in the anion layers. From analyses of the magnetic heat capacity data, we indicate that the two compounds show unconventional thermodynamic behaviors inherent in the π-d interacting layered system. In the case of κ -(BETS) 2FeB r4 , a small hump structure was observed in the magnetic heat capacity below the transition temperature when a magnetic field was applied parallel to the a axis. In the case of κ -(BETS) 2FeC l4 , a similar hump structure was observed at 0 T that remained in the data with magnetic fields applied parallel to the a axis. We demonstrate that the temperature dependencies of the magnetic heat capacities scale well by normalizing the temperatures with dominant one-dimensional direct interactions (Jdd/kB) of each compound. The field dependencies of the transition temperatures and the hump structures are elucidated in one simple magnetic field vs temperature (H -T ) phase diagram. These results indicate that the thermodynamic features of both κ-type BETS salts are essentially equivalent, and the observed hump structures are derived from the one-dimensional Jdd interaction characters, which are still influential for magnetic features even in the long-range magnetic ordered states.

  11. Synthesis, characterization, and physical properties of two new magnetic organic metals, [BEDT-TTF]{sub 4}[C(CN){sub 2}CONH{sub 2}]CuX{sub x} (X = Cl and Br{sub 0.77}Cl{sub 0.22})

    SciTech Connect

    Wang, H.H.; Geiser, U.; Kumar, S.K.

    1995-12-31

    Two new BEDT-TTF based charge transfer salts, [BEDT-TTF]{sub 4}[C(CN){sub 2}CONH{sub 2}]CuX{sub 2} (X = Cl and Br{sub 0.77}Cl{sub 0.22}) have been synthesized and characterized with use of X-ray diffraction, Energy Dispersive Spectroscopy (EDS), and Raman spectroscopy. ESR spectroscopy reveals that the anion layer contains 3% of paramagnetic Cu(II) species which exhibit Curie-Weiss behavior with a Weiss constant of {theta} = {minus}2.8 K. Both compounds are metallic below 150 K. AC susceptibility, RF penetration depth, and RF impedance measurements under pressure do not reveal signals of superconductivity.

  12. Environmentally assisted cracking of two-phase Fe-Mn-Al alloys in NaCl solution

    NASA Astrophysics Data System (ADS)

    Shih, S.-T.; Tsu, I.-F.; Perng, T.-P.

    1993-02-01

    Three two-phase Fe-Mn-Al alloys with nominal compositions, Fe-24Mn-9Al, Fe-27Mn-9Al-3Cr,. and Fe-27Mn-9Al-6Cr, were prepared in the solution-treated and cold-rolled conditions. The fractions of ferrite in the solution-treated condition were controlled at 46 to 60 pct, mainly by adjusting the carbon content and the relative amounts of Mn and Al. The ferrite fractions were reduced to 30 to 37 pct after 75 pct deformation by cold-rolling. Specimens were tensile tested at open circuit in aerated 3.5 pct NaCl solution at slow strain rates ranging from 4 × 10-7 to 4 × 10-5 s-1 at room temperature. All of the alloys were quite susceptible to environmentally assisted cracking (EAC). The deformed specimens showed less susceptibility, presumably because the plasticity was already too limited. The EAC appeared to occur at or after the onset of plastic deformation. In this alloy system, the ferritic phase was less resistant to EAC than the austenitic phase, in contrast to the Fe-Cr-Ni stainless steels. The crack propagated preferentially through the ferrite grains or along the ferrite/austenite grain boundaries. The addition of up to 6 pct Cr did not improve the EAC resistance.

  13. Mechanism of reaction in NaAlCl4 molten salt batteries with nickel felt cathodes and aluminum anodes. 2: Experimental results and comparison with model calculations

    NASA Astrophysics Data System (ADS)

    Knutz, B. C.; Berg, R. W.; Hjuler, H. A.; Bjerrum, N. J.

    1993-12-01

    The battery systems: Al/NaCl-AlCl3-Al2 X3/Ni-felt (X = S, Se, Te) and the corresponding system without chalcogen have been studied experimentally at 175 C. Charge/discharge experiments, performed on cells with NaCl saturated melts, show that advantages with regard to rate capability and cyclability can be obtained with systems containing dissolved chalcogen compared with the chalcogen-free system. Exchange of chalcogen between cathode and electrolyte during cycling was confirmed by performing gravimetric analysis and Raman spectroscopy of the electrolytes. Cathode reactions were studied by coulometric titrations (performed on cells with slightly acidic NaCl-AlCl3 melts and small amounts of chalcogen) and compared with model calculations. Cells containing chalcogen revealed at least three voltage plateaus during cycling. The lowest plateau is associated with formation/decomposition of essentially Ni(y)S(z) an d Ni(y)Se(z) in the sulfide and selenide system, respectively. Cells containing selenide revealed extra capacity below the Ni(y) Se(z)-plateau, most probably associated with a Al(v)Ni(y)Se(z) compound. On the second plateau of sulfide systems NiCl2 or a Ni(y)S(z) Cl(2y - 2z) compound with y greater than (4.4 +/- 0.2), z is formed during charging. Reduction of the formed compound to Ni takes place via consumption of sodium chloride.

  14. Alkaline hydrolysis of dimethyl terephthalate in the presence of [LiAl{sub 2}(OH){sub 6}]Cl.2H{sub 2}O

    SciTech Connect

    Lei Lixu . E-mail: lixu.lei@seu.edu.cn1; Zhang Weifeng; Hu Meng; Zheng Hegen

    2006-11-15

    The alkaline hydrolysis of dimethyl terephthalate (DMT) in the presence of [LiAl{sub 2}(OH){sub 6}]Cl has been investigated to demonstrate a possible application of anion exchange facility of layered double hydroxides (LDHs) to control chemical reactions. The results show that (i) in the alkaline hydrolysis of DMT in the presence of [LiAl{sub 2}(OH){sub 6}]Cl, most of the interlayer Cl{sup -} of [LiAl{sub 2}(OH){sub 6}]Cl is quickly replaced by OH{sup -} in the alkaline solution because the LDH host favors OH{sup -} more; (ii) the alkaline hydrolysis of DMT in the presence of [LiAl{sub 2}(OH){sub 6}]Cl is faster than the reaction of DMT and [LiAl{sub 2}(OH){sub 6}]OH; (iii) The hydrolysis of DMT in a buffer solution of pH{approx}8 takes longer time to reach equilibrium than the alkaline hydrolysis of DMT in the presence of [LiAl{sub 2}(OH){sub 6}]Cl. It is believed that the selective anion exchange chemistry of the LDH plays a key role in storage and controlled release of active reactant, that is, OH{sup -}, thus make the hydrolysis proceeds in a controlled way. - Graphical abstract: XRD patterns of the solid products of the alkaline hydrolysis of dimethyl terephthalate (DMT) in the presence of [LiAl{sub 2}(OH){sub 6}]Cl at 70 deg. C halted at different time, which shows that [LiAl{sub 2}(OH){sub 6}]Cl turns out to be [LiAl{sub 2}(OH){sub 6}]OH, and [LiAl{sub 2}(OH){sub 6}]{sub 2}TP forms gradually. In this reaction, the alkaline hydrolysis of DMT is controlled by replacement of Cl{sup -} in [LiAl{sub 2}(OH){sub 6}]Cl by OH{sup -}, and subsequent replacement of OH{sup -} in [LiAl{sub 2}(OH){sub 6}]OH by terephthalate anion.

  15. A Potentiometric, Spectrophotometric and Pitzer Ion-Interaction Study of Reaction Equilibria in the Aqueous H+-Al3+, H+-Oxalate and H+-Al3+-Oxalate Systems up to 5 mol*dm-3 NaCl

    SciTech Connect

    Boily, Jean F.; Qafoku, Odeta; Felmy, Andrew R.

    2007-12-01

    Aluminium-oxalate complexation was determined in acidic media of aqueous NaCl solutions ranging from 0.1-5.0 mol•dm-3. Complexation in the H+-Al3+ and H+-Oxalate systems was also studied to provide a set of internally consistent thermodynamic data. The ionic strength dependent formation constants describing the stabilities of the Al3+, AlOH2+, Al3(OH)45+, Al13O4(OH)247+, H2L, HL-, L2-, AlL+, AlL2- and AlL33- species (where L is the oxalate ion) was also described using a Pitzer ion interaction model. The derived parameters can be used to predict chemical speciation in the H+-Al3+-Oxalate system in the 0.1-5.0 mol•dm-3 NaCl range.

  16. Exchange Coupling in an Isostructural Series of Face-Sharing Bioctahedral Complexes [LM(II)(&mgr;-X)(3)M(II)L]BPh(4) (M = Mn, Fe, Co, Ni, Zn; X = Cl, Br; L = 1,4,7-Trimethyl-1,4,7-triazacyclononane).

    PubMed

    Bossek, Ursula; Nühlen, Daniela; Bill, Eckhard; Glaser, Thorsten; Krebs, Carsten; Weyhermüller, Thomas; Wieghardt, Karl; Lengen, Marek; Trautwein, A. X.

    1997-06-18

    The reaction of the divalent metal halides ZnCl(2), ZnBr(2), MnCl(2).4CH(3)CN, MnBr(2), FeCl(2).4CH(3)CN, CoCl(2).4CH(3)CN, CoBr(2), NiCl(2).6H(2)O, and NiBr(2), respectively, with the macrocycle 1,4,7-trimethyl-1,4,7-triazacyclononane (L) (1:1) in anhydrous acetonitrile, acetone, chloroform, or ethanol affords upon additon of NaBPh(4) the isomorphous series of complexes [LM(II)(&mgr;-X)(3)M(II)L]BPh(4): 1, M = Zn, X = Cl; 2, Zn, Br; 3, Mn, Cl; 4, Mn, Br; 5, Fe, Cl; 6, Co, Cl; 7, Co, Br; 8, Ni, Cl; 9, Ni, Br. Six of these complexes have been structurally characterized by single-crystal X-ray crystallography; they crystallize in the triclinic space group P&onemacr; (No. 2) with Z = 4. Crystal data are as follows 1, a = 16.654(1), b = 17.042(1), c = 17.684(1) Å, alpha = 97.30(1), beta = 93.58(1), gamma = 117.46(1) degrees; 3, a = 16.632(8), b = 17.012(8), c = 17.855(5) Å, alpha = 97.16(3), beta = 93.37(3), gamma = 117.24(3) degrees; 5, a = 16.658(3), b = 17.064(3), c = 17.741(4) Å, alpha = 97.32(3), beta = 93.47(3), gamma = 117.36(3) degrees; 6, a = 16.640(3), b = 17.040(3), c = 17.686(4) Å, alpha = 97.39(3), beta = 93.58(3), gamma = 117.39(3) degrees; 8, a = 16.608(3), b = 16.995(3), c = 17.555(3) Å, alpha = 97.36(1), beta = 93.52(1), gamma = 117.52(1) degrees; 9, a = 16.680(3), b = 17.016(2), c = 17.715(3)Å, alpha = 96.99(1), beta = 93.70(1), gamma = 117.42(1) degrees. All complexes consist of a dinuclear, face-sharing bioctahedral monocation with three &mgr;(2)-Cl or &mgr;(2)-Br bridging ligands and two LM fragments and well-separated tetraphenylborate anions (1:1). The cations cocrystallize in two different forms: an enantiomeric form with (lambdalambdalambda) (or (deltadeltadelta)) conformation at both LM fragments and a meso form with an (lambdalambdalambda) conformation at one LM fragment and (deltadeltadelta) at the other (ratio 1:1). From temperature-dependent magnetic susceptibility measurements (2-293 K) it was established that the spins of the

  17. Growth mechanism of atomic-layer-deposited TiAlC metal gate based on TiCl4 and TMA precursors

    NASA Astrophysics Data System (ADS)

    Jinjuan, Xiang; Yuqiang, Ding; Liyong, Du; Junfeng, Li; Wenwu, Wang; Chao, Zhao

    2016-03-01

    TiAlC metal gate for the metal-oxide-semiconductor field-effect-transistor (MOSFET) is grown by the atomic layer deposition method using TiCl4 and Al(CH3)3(TMA) as precursors. It is found that the major product of the TiCl4 and TMA reaction is TiAlC, and the components of C and Al are found to increase with higher growth temperature. The reaction mechanism is investigated by using x-ray photoemission spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The reaction mechanism is as follows. Ti is generated through the reduction of TiCl4 by TMA. The reductive behavior of TMA involves the formation of ethane. The Ti from the reduction of TiCl4 by TMA reacts with ethane easily forming heterogenetic TiCH2, TiCH=CH2 and TiC fragments. In addition, TMA thermally decomposes, driving Al into the TiC film and leading to TiAlC formation. With the growth temperature increasing, TMA decomposes more severely, resulting in more C and Al in the TiAlC film. Thus, the film composition can be controlled by the growth temperature to a certain extent. Project supported by the Key Technology Study for 16/14 nm Program of the Ministry of Science and Technology of China (Grant No. 2013ZX02303).

  18. Mechanistic and energetic aspects of the thermal and photochemical redox chemistry of the octanuclear cubane complexes, Fe(III)(8)(mu(4)-O(4))(mu-pyrazolate)(12)X(4) (X = Cl or Br).

    PubMed

    Ferraudi, Guillermo; Piñero, Dalice; Chakraborty, Indranil; Raptis, Raphael G; Lappin, A Graham; Berlin, Nicholas

    2010-05-13

    The mechanisms of the thermal and photochemical redox reactions of clusters [Fe(III)(8)(mu(4)-O(4))(mu-Pz)(12)X(4)] (Pz = pyrazolate anion, X = Cl or Br) were investigated in this work. Reactions of the complexes with e(-)(sol), C(*)H(2)OH, and several powerful reducing transition metal complexes were investigated using the pulse radiolysis technique. Reaction rates of the outer-sphere electron transfer reactions with transition metal complexes had to be rationalized by invoking the formation of a [Fe(III)(7)Fe(II) '(mu(4)-O(4))(mu-Pz)(12)X(4)](-) intermediate or excited state. A transient species observed in the reaction of the e(-)(sol) with the cubanes can be either an excited state or a reaction intermediate mediating the formation of the stable product, [Fe(III)(7)Fe(II)(mu(4)-O(4))(mu-Pz)(12)X(4)](-). Photoredox reactions, characteristic of the ligand X(-) to Fe(III) charge transfer excited sates, were observed in the 350 nm steady state and 351 nm laser flash irradiations of the cubanes. Quantum yields are limited by the rapid recombination of the photofragments. The charge transfer spectroscopy of the products was rationalized on the basis of parameters derived from the thermal electron transfer reactions.

  19. Neutron diffraction studies of nuclear and magnetic structures in the S=1/2 square Heisenberg antiferromagnets (d{sub 6}-5CAP){sub 2}CuX{sub 4} (X=Br and Cl)

    SciTech Connect

    Coomer, F. C.; Bondah-Jagalu, V.; Grant, K. J.; Harrison, A.; McIntyre, G. J.; Roennow, H. M.; Feyerherm, R.; Wand, T.; Meissner, M.; Visser, D.; McMorrow, D. F.

    2007-03-01

    We report the neutron scattering studies of the nuclear and magnetic structures of deuterated samples of the model two-dimensional S=1/2 Heisenberg antiferromagnets on a square lattice (d{sub 6}-5CAP){sub 2}CuCl{sub 4} and (d{sub 6}-5CAP){sub 2}CuBr{sub 4} (where 5CAP is 2-amino-5-chloropyridinium). Interest in these materials stems from the fact that they have relatively weak exchange between the magnetic ions, and it is therefore possible to perturb their magnetic structures and excitations significantly in experimentally accessible magnetic fields, and thereby access new quantum disordered states. We succeeded in growing fully deuterated single crystals and determined the nuclear and magnetic structures of the bromide at 10 and 1.8 K, respectively, confirming the four-sublattice spin structure expected for systems, where both inter- and intraplane exchange interactions are antiferromagnetic. The determination of the full crystal structure of the bromide highlights the possibility that interlayer exchange may also propagate via hydrogen bonds to and through the 5CAP molecule. We also determined the critical exponents for the sublattice magnetization of the bromide and mapped out the H-T phase diagram of the chloride up to 5 T.

  20. High-field magnetization studies of spin-dimer behaviors on low-dimensional spin systems, LiCu2-xZnxO2 and FeTe3O7X (X = Cl, Br)

    NASA Astrophysics Data System (ADS)

    Her, J. L.; Hsu, H. C.; Matsuda, Y. H.; Kindo, K.; Chou, C. C.; Yang, H. D.; Berger, H.; Chou, F. C.

    2013-03-01

    High-field magnetization of two kinds of low-dimensional spin system was studied in pulsed magnets. Several anomalies were clearly observed in dm/dH curves of doped LiCu2-xZnxO2 (x = 0.07) at low temperatures (1.3 K < T < 20 K). When temperature decreases, the anomalies sharper / splits at certain critical temperatures which are related to the formation of isolated spin-dimer and spin freezing state. A field-induced spin density wave state was suggested to exist at high magnetic fields. The doping of Zn2+ ions breaks the spin-chain of Cu2+ ions, leading to the formation of isolated spin-dimers and lowering the critical field of formation of spin density state. The magnetization process measurements were preformed on another series of samples, FeTe3O7X (X = Cl, Br), which has spin-dimer, formed by Fe3+ ions, at low temperatures and magnetic fields up to 100 T. At low temperatures, the magnetization processes show four step-like structures, which have nearly equal spaces of 25 T. Both samples show similar behavior. These steps are considered to be the magnetic excitation of the antiferromagnetic spin-dimers.

  1. Theoretical study on the identity ion pair SN2 reactions of LiX with CH3SX (X=Cl, Br, and I): structure, mechanism, and potential energy surface.

    PubMed

    Ren, Yi; Gai, Jing-Gang; Xiong, Yan; Lee, Kuo-Hsing; Chu, San-Yan

    2007-07-26

    Three archetypal ion pair nucleophilic substitution reactions at the methylsulfenyl sulfur atom LiX+CH3SX-->XSCH3+LiX (X=Cl, Br, and I) are investigated by the modified Gaussian-2 theory. Including lithium cation in the anionic models makes the ion pair reactions proceed along an SN2 mechanism, contrary to the addition-elimination pathway occurring in the corresponding anionic nucleophilic substitution reactions X-+CH3SX-->XSCH3+X-. Two reaction pathways for the ion pair SN2 reactions at sulfur, inversion and retention, are proposed. Results indicate the inversion pathway is favorable for all the halogens. Comparison of the transition structures and energetics for the ion pair SN2 at sulfur with the potential competition ion pair SN2 reactions at carbon LiX+CH3SX-->XCH3+LiXS shows that the SN2 reactions at carbon are not favorable from the viewpoints of kinetics and thermodynamics.

  2. Temperature dependence of the magnetic moment relaxation rate of the organic superconductor x-(BEDT-TFF){sub 2}Cu[N(CN){sub 2}]Cl{sub 0.5}Br{sub 0.5}

    SciTech Connect

    Primenko, A.E.; Kuznetsov, V.D.; Metlushko, V.V.; Mendeleev, D.V.; Kushch, N.D.; Yagubskii, E.B.

    1994-06-01

    The authors have investigated relaxation of the residual magnetic moment of x-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl{sub 0.5}Br{sub 0.5}, an organic superconductor, in the temperature range 2.4 to 9.5 K. In these investigations, they observed that the reduced relaxation rate S=d 1n P{sub m}/dt ln t remains constant for T/T{sub c} < 0.7, and then increases rapidly with T. They also determined the temperature dependence of the critical current density in zero magnetic field. In comparing the functions s(T) and J{sub c}(T) for this superconductor with their counterparts for single-crystal high-temperature superconductors, they have found that their behavior is most analogous to that of s(T) and J{sub c}(T) for YBaCuO. Using the relaxation curves, they have calculated the current-voltage characteristics E(J), which are well-described by a power law function of the type E{proportional_to}J{sup n}. 15 refs., 7 figs.

  3. Jet Cooled Laser Induced Fluorescence Spectroscopy of FCH2CH2O and Other Photo-Fragments of XCH2CH2ONO (X=F, Cl, Br, Oh)

    NASA Astrophysics Data System (ADS)

    Chhantyal-Pun, Rabi; Chen, Ming-Wei; Miller, Terry A.

    2011-06-01

    HOCH2CH2O is one of the prototypical hydroxyalkoxy intermediates formed in the OH mediated oxidation of olefins in the atmosphere. Specifically, HOCH2CH2O is produced from NO assisted reduction of HOCH2CH2OO which in turn is formed by the OH mediated oxidation of ethene in the atmosphere. Halogen substituted ethoxy can be a model to study the hydroxy substituted ethoxy. Our group has successfully studied different primary, secondary and unsaturated alkoxy radicals using Laser Induced Fluorescence technique (LIF) coupled with supersonic free jet expansion in the past. In this talk we will present the jet cooled LIF spectrum of FCH2CH2O. FCH2CH2O was produced in the jet by 351nm photodissociation of FCH2CH2ONO. Aided by ab inito calculations and past experiments, we were able to assign our spectrum to different conformers of FCH2CH2O based on the G(±120°) and T(O°) orientations of the OCCF dihedral angle. Besides FCH2CH2O, we also found transitions belonging to HCHO and CH2CHO from FCH2CH2ONO photodissociation. HCHO and CH2CHO were also found in Cl, Br and OH substituted precursors.

  4. Novel CX⋯π halogen bonds in complexes of acetylene and its derivatives of Na and MPH3 (M=Cu, Ag, Au) with XCCF (X=Cl, Br, I).

    PubMed

    Zhuo, Hongying; Liu, Mingjuan; Li, Qingzhong; Li, Wenzuo; Cheng, Jianbo

    2014-06-05

    Ab initio calculations have been carried out for a variety of model systems with a T-shaped CX⋯π motif. The CX⋯π interaction of acetylene with the halogen donor molecule XCCF (X=Cl, Br, I) is invariably found to be weak with the interaction energy less than 11kJ/mol in magnitude. Substitution of the two protons in acetylene with more electron-donating sodium atoms increases the π electron density in the CC bond and leads to a substantial enhancement in its interaction with the halogen donor. The calculated interaction energies increase to as much as 73kJ/mol in the case of C2Na2-ICCF. The interaction of XCCF with a model coinage metal ethynide, H3PMCCMPH3 (M=Cu, Ag, Au), is intermediate between these two extremes, and the interaction energy is related to the nature of coinage metals. The CX⋯π halogen bonds have been analyzed with natural bond orbital, atoms in molecules, and energy decomposition.

  5. Absolute NMR shielding scales and nuclear spin–rotation constants in {sup 175}LuX and {sup 197}AuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br and {sup 127}I)

    SciTech Connect

    Demissie, Taye B. Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth; Jaszuński, Michał

    2015-10-28

    We present nuclear spin–rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in {sup 175}LuX and {sup 197}AuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br, {sup 127}I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin–rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin–rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin–rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin–rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides.

  6. Monohalogenated ferrocenes C(5)H(5)FeC(5)H(4)X (X = Cl, Br and I) and a second polymorph of C(5)H(5)FeC(5)H(4)I.

    PubMed

    Romanov, Alexander S; Mulroy, Joseph M; Khrustalev, Victor N; Antipin, Mikhail Yu; Timofeeva, Tatiana V

    2009-11-01

    The structures of the three title monosubstituted ferrocenes, namely 1-chloroferrocene, [Fe(C(5)H(5))(C(5)H(4)Cl)], (I), 1-bromoferrocene, [Fe(C(5)H(5))(C(5)H(4)Br)], (II), and 1-iodoferrocene, [Fe(C(5)H(5))(C(5)H(4)I)], (III), were determined at 100 K. The chloro- and bromoferrocenes are isomorphous crystals. The new triclinic polymorph [space group P-1, Z = 4, T = 100 K, V = 943.8 (4) A(3)] of iodoferrocene, (III), and the previously reported monoclinic polymorph of (III) [Laus, Wurst & Schottenberger (2005). Z. Kristallogr. New Cryst. Struct. 220, 229-230; space group Pc, Z = 4, T = 100 K, V = 924.9 A(3)] were obtained by crystallization from ethanolic solutions at 253 and 303 K, respectively. All four phases contain two independent molecules in the unit cell. The relative orientations of the cyclopentadienyl (Cp) rings are eclipsed and staggered in the independent molecules of (I) and (II), while (III) demonstrates only an eclipsed conformation. The triclinic and monoclinic polymorphs of (III) contain nonbonded intermolecular I...I contacts, causing different packing modes. In the triclinic form of (III), the molecules are arranged in zigzag tetramers, while in the monoclinic form the molecules are arranged in zigzag chains along the a axis. Crystallographic data for (III), along with the computed lattice energies of the two polymorphs, suggest that the monoclinic form is more stable.

  7. Relationship between force constants and bond lengths for CX (X = C, Si, Ge, N, P, As, O, S, Se, F, Cl and Br) single and multiple bonds: formulation of Badger's rule for universal use.

    PubMed

    Kurita, Eiichi; Matsuura, Hiroatsu; Ohno, Keiichi

    2004-11-01

    Geometries and harmonic vibrational wave numbers were calculated on a series of simple compounds that contain the atoms of elements in the groups 14-17 by density functional theory at the B3LYP/6-311++G(3df,2pd) level. The calculated wave numbers agree well with the observed harmonic wave numbers with substantially the same accuracy for the compounds of the different groups. The stretching force constants of the CX (X = C, Si, Ge, N, P, As, O, S, Se, F, Cl and Br) single and multiple bonds were obtained. The CX stretching force constants increase with a decrease of the bond lengths as the element X in the same period goes from left to right in the periodic table. The individual intrinsic properties of the CX bonds are lost gradually with increasing the period of the element X. The unified interpretation of Badger's rule has enabled the formulation of a common equation for universal use f = 2.8 R(-3) to relate the force constants f (10(2) N m(-1)) and the reduced bond lengths R (10(-10) m).

  8. Refractive index dispersion of AgCl1-xBrx (0≤x≤1) and Ag1-xTlxBr1-xIx (0≤x≤0.05)

    NASA Astrophysics Data System (ADS)

    Korsakov, Alexandr S.; Vrublevsky, Dmitry S.; Lvov, Alexandr E.; Zhukova, Liya V.

    2017-02-01

    For polycrystalline AgCl1-xBrx (0 ≤ x ≤ 1) and Ag1-xTlxBr1-xIx (0 ≤ x ≤ 0.05) thin plates manufactured by hot embossing, we recorded the ultraviolet (UV) to near-infrared (NIR) transmission spectra in order to reveal the absorption edge and to measure the refractive index at short wavelengths. The former moves towards longer wavelengths and the latter increases significantly, when the substituting agent content in the solid solution (x) is being increased. Using mid-infrared (MIR) spectra, recorded by Fourier-transform infrared spectroscopy (FTIR), we determined both real (n) and imaginary (k) parts of the refractive index at 4.5, 5.0, 8.0, 12.0, 14.0 μm. These data, together with the ones collected earlier with He-Ne laser and at 10.6 μm via FTIR, allow observing that the introduction of a heavy substituting agent into a host lattice forces the refractive index to grow gradually at a fixed wavelength and to fall considerably within each composition (vice versa for the extinction coefficient), especially in the NIR. Fresnel reflection (R) and absorption coefficients (K) were also calculated, and several error-calculation equations for n, k, K, and R were proposed concerning all contributions of each approach used.

  9. Absolute NMR shielding scales and nuclear spin-rotation constants in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br and (127)I).

    PubMed

    Demissie, Taye B; Jaszuński, Michał; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth

    2015-10-28

    We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br, (127)I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin-rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides.

  10. Absolute NMR shielding scales and nuclear spin-rotation constants in 175LuX and 197AuX (X = 19F, 35Cl, 79Br and 127I)

    NASA Astrophysics Data System (ADS)

    Demissie, Taye B.; Jaszuński, Michał; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth

    2015-10-01

    We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in 175LuX and 197AuX (X = 19F, 35Cl, 79Br, 127I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin-rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides.

  11. First-principles study of the magnetic ground state and magnetization process of the kagome francisites Cu3Bi (SeO3)2 O2X (X =Cl ,Br )

    NASA Astrophysics Data System (ADS)

    Nikolaev, S. A.; Mazurenko, V. V.; Tsirlin, A. A.; Mazurenko, V. G.

    2016-10-01

    We explore the magnetic behavior of the kagome francisites Cu3Bi (SeO3)2 O2X (X =Cl ,Br ) by using first-principles electronic structure calculations. To this end, we propose an approach based on the effective Hubbard model in the Wannier functions basis constructed on the level of local-density approximation. The ground-state spin configuration is determined by a mean-field Hartree-Fock solution of the Hubbard model both in zero magnetic field and in applied magnetic fields. Additionally, parameters of an effective spin Hamiltonian are obtained by taking into account hybridization effects and spin-orbit coupling. We show that only the former approach based on the Hartree-Fock approximation allows for a complete description of the anisotropic magnetization process. While our calculations confirm that the canted zero-field ground state arises from a competition between ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor couplings in the kagome planes, weaker anisotropic terms are crucial for fixing spin directions and for the strong anisotropy of the magnetization. We show that the Hartree-Fock solution of an electronic Hamiltonian is a viable alternative to the analysis of effective spin Hamiltonians when magnetic ground states and their evolution in external field are concerned.

  12. Structural and morphological characterization of Mg0.8Al0.2(OH)2Cl0.2 hydrotalcite produced by mechanochemistry method

    NASA Astrophysics Data System (ADS)

    Fahami, Abbas; Beall, Gary W.

    2016-01-01

    Chlorine intercalated Mg-Al layered double hydroxides (Mg-Al-Cl-LDH) with a chemical formula Mg0.8Al0.2(OH)2Cl0.2 were successfully produced by the one-step mechanochemistry method and subsequent water washing followed by drying in oven for 1 h at 80 °C. The samples were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), elemental mapping analysis, transmission electron microscopy (TEM), X-ray fluorescence (XRF), and the differential thermogravimetric analysis (DTGA). Results revealed that the structural characteristics of Mg-Al-Cl-LDH were affected strongly by milling time. At the beginning of milling (up to 1 h), Hydrotalcite (HT) and Brucite were the dominant phases, while the progressive mechanical activation was completed as milling time increased, which resulted in the formation of nanostructured Mg-Al-Cl-LDH. Based on XRD and FTIR data, Mg0.8Al0.2(OH)2Cl0.2 with high purity was obtained at 5 h milling. The interlayer spacing of LDH is also strongly influenced by milling time so that it escalated from 7.737±0.001 to 8.005±0.002 (1-15 h) and then decreased to 7.937±0.001 for 20 h milled sample. Electron microscopic observation displayed that the final product had hexagonal platelet structure with lateral dimension of 20-100 nm. Therefore, the synthesis of Mg0.8Al0.2(OH)2Cl0.2 via mechanochemistry owing to simplicity and versatility can be a promising candidate for use in catalyst carriers, drug delivery, and gene delivery.

  13. Cs7Sm11[TeO3]12Cl16 and Rb7Nd11[TeO3]12Br16, the new tellurite halides of the tetragonal Rb6LiNd11[SeO3]12Cl16 structure type

    NASA Astrophysics Data System (ADS)

    Charkin, Dmitri O.; Black, Cameron; Downie, Lewis J.; Sklovsky, Dmitry E.; Berdonosov, Peter S.; Olenev, Andrei V.; Zhou, Wuzong; Lightfoot, Philip; Dolgikh, Valery A.

    2015-12-01

    Two new rare-earth - alkali - tellurium oxide halides were synthesized by a salt flux technique and characterized by single-crystal X-ray diffraction. The structures of the new compounds Cs7Sm11[TeO3]12Cl16 (I) and Rb7Nd11[TeO3]12Br16 (II) (both tetragonal, space group I4/mcm) correspond to the sequence of [MLn11(TeO3)12] and [M6X16] layers and bear very strong similarities to those of known selenite analogs. We discuss the trends in similarities and differences in compositions and structural details between the Se and Te compounds; more members of the family are predicted.

  14. Quantification of copper phases, their reducibility and dispersion in doped-CuCl2/Al2O3 catalysts for ethylene oxychlorination.

    PubMed

    Muddada, N B; Olsbye, U; Leofanti, G; Gianolio, D; Bonino, F; Bordiga, S; Fuglerud, T; Vidotto, S; Marsella, A; Lamberti, C

    2010-09-28

    The comprehensive understanding of the composition, behaviour and reactivity of a catalyst used inside industrial plants is an extremely hard task that is rarely achieved. It requires the use of different spectroscopic techniques, applied under in situ or in operando conditions, and combined with the investigation of the catalyst activity. Often the operating experimental conditions are different from technique to technique and the different results must be compared with care. In the present contribution, we combined in situ XANES/EXAFS, IR spectroscopy of adsorbed CO, CO chemisorption and catalytic tests performed using a pulse reactor in depletive mode. This multitechnical approach resulted in the understanding of the role that dopants (LiCl, KCl, CsCl, MgCl(2) LaCl(3)) have in the nature, relative fraction, reducibility and dispersion of Cu-phases on CuCl(2)/gamma-Al(2)O(3) catalysts for oxychlorination reaction, a key step of the PVC chemistry. In the undoped catalyst two Cu phases coexist: Cu-aluminate and supported CuCl(2), being the latter the only active one [J. Catal., 2000, 189, 91]. EXAFS and XANES highlighted that all dopants contribute more or less efficiently in increasing the fraction of the active copper species, that reaches a value of almost 100% in the case of MgCl(2) or LaCl(3). EXAFS directly, and IR indirectly, proved that the addition of KCl or CsCl (and less efficiently of LiCl) results in the formation of mixed CuK(x)Cl(2+x) or CuCs(x)Cl(2+x) phases, so altering the chemical nature of the active phase. XANES spectroscopy indicates that addition of MgCl(2) or LaCl(3) does not affect the reducibility by ethylene (under static conditions) of the active CuCl(2) phase and that the reducibilility of the new copper-dopant mixed chloride are in the order CuCl(2) > CuLi(x)Cl(2+x) > CuK(x)Cl(2+x) > CuCs(x)Cl(2+x). However, when reduction is done inside a pulse reactor, a more informative picture comes out. The last technique is able to differentiate

  15. X-ray powder diffraction, vibration and thermal studies of [A{sub 0.92}(NH{sub 4}){sub 0.08}]{sub 2}TeCl{sub 4}Br{sub 2} with A = Cs, Rb: Influence of mixed cationic and anionic substitutions

    SciTech Connect

    Aribia, W. Ben; Abdelmouleh, M.; Kabadou, A.; Van Der Lee, A.

    2012-05-15

    Graphical abstract: The structures of [A{sub 0.92}(NH{sub 4}){sub 0.08}]{sub 2}TeCl{sub 4}Br{sub 2} with A = Cs, Rb belong to the tetragonal {beta}-K{sub 2}SnCl{sub 6} structure type. Highlights: Black-Right-Pointing-Pointer The two new compound crystallises in P4/mnc tetragonal space group. Black-Right-Pointing-Pointer The structure is considered as isolated octahedred TeCl{sub 4}Br{sup 2-}. Black-Right-Pointing-Pointer The octahedra connected by ionic and hydrogen bonding through the Cs/Rb or N atoms. Black-Right-Pointing-Pointer A DTA/TGA experiment reveals one endothermic peak at 780 K for these compounds. Black-Right-Pointing-Pointer One endothermic peak is detected at around 213 K by DSC experiment. -- Abstract: The crystal structures of [A{sub 0.92}(NH{sub 4}){sub 0.08}]{sub 2}TeCl{sub 4}Br{sub 2} with A = Cs, Rb have been determined using X-ray powder diffraction techniques. The two compounds crystallize in the tetragonal space group P4/mnc, with the unit cell parameters: a = 7.452(1) Angstrom-Sign , c = 10.544(3) Angstrom-Sign , Z = 2 and a = 7.315(2) Angstrom-Sign , c = 10.354(4) Angstrom-Sign , Z = 2 in the presence of Cs and Rb, respectively. These two compounds have an antifluorite-type arrangement of NH{sub 4}{sup +}/Rb{sup +}/Cs{sup +} and octahedral TeCl{sub 4}Br{sub 2}{sup 2-} anions. The stability of these structure is by ionic and hydrogen bonding contacts: A Midline-Horizontal-Ellipsis Cl, A Midline-Horizontal-Ellipsis Br and N-H Midline-Horizontal-Ellipsis Cl, N-H Midline-Horizontal-Ellipsis Br. The different vibrational modes of these powders were analysed by FTIR and Raman spectroscopic studies. A DTA/TGA experiment reveals one endothermic peak at 780 K implicating the decomposition of the sample. At low temperature, one endothermic peak in thermal behavior is detected at around 213 K by DSC experiment. This transition was confirmed by dielectric measurements.

  16. Investigation of electrochemical etch differences in AlGaAs heterostructures using Cl{sub 2} ion beam assisted etching

    SciTech Connect

    Anglin, Kevin Goodhue, William D.; Swint, Reuel B.; Porter, Jeanne

    2015-03-15

    A deeply etched, anisotropic 45° and 90° mirror technology is developed for Al{sub x}Ga{sub 1−x}As heterostructures using a Cl{sub 2} ion beam assisted etching system. When etching vertically, using a conductive low-erosion Ni mask, electrochemical etch differences between layers with various Al mole fractions caused nonuniform sidewall profiles not seen in semi-insulating GaAs test samples. These variations, based on alloy composition, were found to be negligible when etching at a 45°. A Si{sub 3}N{sub 4}-Ni etch mask is designed in order to electrically isolate charge buildup caused by the incoming Ar{sup +} ion beam to the Ni layer, preventing conduction to the underlying epitaxial layers. This modification produced smoothly etched facets, up to 8 μm in depth, enabling fabrication of substrate–surface-emitting slab-coupled optical waveguide lasers and other optoelectronic devices.

  17. Internally consistent thermodynamic data for aqueous species in the system Na-K-Al-Si-O-H-Cl

    NASA Astrophysics Data System (ADS)

    Miron, George D.; Wagner, Thomas; Kulik, Dmitrii A.; Heinrich, Christoph A.

    2016-08-01

    A large amount of critically evaluated experimental data on mineral solubility, covering the entire Na-K-Al-Si-O-H-Cl system over wide ranges in temperature and pressure, was used to simultaneously refine the standard state Gibbs energies of aqueous ions and complexes in the framework of the revised Helgeson-Kirkham-Flowers equation of state. The thermodynamic properties of the solubility-controlling minerals were adopted from the internally consistent dataset of Holland and Powell (2002; Thermocalc dataset ds55). The global optimization of Gibbs energies of aqueous species, performed with the GEMSFITS code (Miron et al., 2015), was set up in such a way that the association equilibria for ion pairs and complexes, independently derived from conductance and potentiometric data, are always maintained. This was achieved by introducing reaction constraints into the parameter optimization that adjust Gibbs energies of complexes by their respective Gibbs energy effects of reaction, whenever the Gibbs energies of reactant species (ions) are changed. The optimized thermodynamic dataset is reported with confidence intervals for all parameters evaluated by Monte Carlo trial calculations. The new thermodynamic dataset is shown to reproduce all available fluid-mineral phase equilibria and mineral solubility data with good accuracy and precision over wide ranges in temperature (25-800 °C), pressure (1 bar to 5 kbar) and composition (salt concentrations up to 5 molal). The global data optimization process adopted in this study can be readily repeated any time when extensions to new chemical elements and species are needed, when new experimental data become available, or when a different aqueous activity model or equation of state should be used. This work serves as a proof of concept that our optimization strategy is feasible and successful in generating a thermodynamic dataset reproducing all fluid-mineral and aqueous speciation equilibria in the Na-K-Al-Si-O-H-Cl system within

  18. The effects of sulfur intercalation on the optical properties of artificial `hackmanite', Na8[Al6Si6O24]Cl1.8S0.1; `sulfosodalite', Na8[Al6Si6O24]S; and natural tugtupite, Na8[Be2Al2Si8O24](Cl,S)2-δ

    NASA Astrophysics Data System (ADS)

    Warner, T. E.; Hutzen Andersen, J.

    2012-02-01

    The minerals `hackmanite' and tugtupite exhibit tenebrescence (reversible photochromism) and photoluminescence. These features are generally attributed to the presence of sulfide species within their structures. But how these optical properties might be affected by intercalating additional amounts of sulfur into their structures was until now unknown. Artificial `hackmanite', Na8[Al6Si6O24]Cl1.8S0.1, and `sulfosodalite', Na8[Al6Si6O24]S, were heated with sulfur in evacuated quartz-glass ampoules over the temperature range 450-1,050°C. This work has shown that sulfur intercalation into Na8[Al6Si6O24]Cl1.8S0.1 destroys the tenebrescence and induces a permanently pale blue and, at higher temperature, a pale green coloration. The effect on Na8[Al6Si6O24]S induced similar colorations but of a deeper hue. Annealing tugtupite, Na8[Be2Al2Si8O24](Cl,S)2-δ under a sulfur atmosphere over the range 600-700°C, destroyed the tenebrescence and resulted in a colorless tugtupite; but did not effect the photoluminescence. This suggests that the chemical species responsible for the tenebrescence in tugtupite is unlikely to be the same as that for the luminescence.

  19. Chemical consequences of radioactive decay. 1. Study of /sup 249/Cf ingrowth into crystalline /sup 249/BkBr/sub 3/: a new crystalline phase of CfBr/sub 3/

    SciTech Connect

    Young, J.P.; Haire, R.G.; Peterson, J.R.; Ensor, D.D.; Fellows, R.L.

    1980-08-01

    Spectrophotometric and x-ray powder diffraction methods have been applied to a study of the ingrowth of californium-249 by ..beta../sup -/ decay of berkelium-249 in crystalline /sup 249/BkBr/sub 3/. It was found that the Cf daughter grows in with the same oxidation state and crystal structure as the parent. Thus, six-coordinate BkBr/sub 3/ (AlCl/sub 3/-type monoclinic structure) generates six-coordinate CfBr/sub 3/, and eight-coordinate BkBr/sub 3/ (PuBr/sub 3/-type orthorhombic structure) generates eight-coordinate CfBr/sub 3/, a previously unknown form of CfBr/sub 3/. It was also found that the daughter Cf(III) in the BkBr/sub 3/ parent compound can be reduced to Cf(II) by treatment with H/sub 2/, as it can in pure CfBr/sub 3/. 5 figures.

  20. Reaction kinetics for the solid state synthesis of the AlH3/MgCl2 nano-composite by mechanical milling.

    PubMed

    Duan, C W; Hu, L X; Sun, Y; Zhou, H P; Yu, H

    2015-09-14

    The process of mechanical milling has been proved to be a cost-effective way to synthesize the AlH3/MgCl2 nano-composite by using MgH2 and AlCl3 as reagents. However, so far there is no comprehensive knowledge of the kinetics of this process. In an effort to predict the reaction progress and optimize the milling parameters, the kinetics of the synthesis of the AlH3/MgCl2 nano-composite by mechanical milling of MgH2 and AlCl3 is experimentally investigated in the present work. The reaction progress or the transformation fraction upon milling for different times is evaluated using the isothermal hydrogen desorption test of the as-milled samples at 220 °C, which is much lower than the threshold temperature for the de-hydriding of the reagent MgH2 but enough for the de-hydriding of the as-synthesized nano-sized AlH3. The effects of milling parameters on the reaction kinetics as well as the underlying mechanism are discussed by referring to the mechanical energy input intensity, the vial temperature and the Gibbs free energy change for the reaction. Furthermore, it is found that the Johnson-Mehl-Avrami (JMA) model can well describe the kinetics theoretically. By fitting the experimental data with the JMA expression, the theoretical kinetics expressions, the equation parameters, and the activation energy are obtained.

  1. Measurements of the ClO radical vibrational band intensity and the ClO + ClO + M reaction product

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.; Orlando, John J.; Hammer, Philip D.; Howard, Carleton J.; Goldman, Aaron

    1988-01-01

    There is considerable interest in the kinetics and concentrations of free radicals in the stratosphere. Chlorine monoxide is a critically important radical because of its role in catalytic cycles for ozone depletion. Depletion occurs under a wide variety of conditions including the Antarctic spring when unusual mechanisms such as the BrO sub x/ClO sub x, ClO dimer (Cl sub 2 O sub 2), and ClO sub x/HO sub x cycles are suggested to operate. Infrared spectroscopy is one of the methods used to measure ClO in the stratosphere (Menzies 1979 and 1983; Mumma et al., 1983). To aid the quantification of such infrared measurements, researchers measured the ClO ground state fundamental band intensity.

  2. Anticooperativity of FHF hydrogen bonds in clusters of the type F- × (HF)n, RF × (HF)n and XF × (HF)n, R = alkyl and X = H, Br, Cl, F

    NASA Astrophysics Data System (ADS)

    Kucherov, S. Yu.; Bureiko, S. F.; Denisov, G. S.

    2016-02-01

    Properties of twenty five hydrogen-bonded complexes, namely, F- × (HF)n (n = 1-6), RF × (HF)n (R = t-Bu, i-Pr, Et, Me; n = 1-3), XF × (HF)n (X = H, Br, Cl; n = 1-2), and FF…HF with the hydrogen bond energy varying in a wide range have been calculated using ab initio methods at the MP2/6-31++G** level. For the first time, the energies, geometrical parameters and vibrational frequencies are obtained for the series of clusters, where the bonding character changes from covalent to van der Waals on the variation of proton-acceptor ability of the base, and the energies are in the range of 45-1 kcal/mol. The mutual influence of multiple hydrogen bonds of F…HF type in clusters, in which a fluorine anion or an atom participates in hydrogen bond formation as the acceptor, is systematically investigated. The relative changes in the values of the considered parameters on the sequential addition of an HF molecule (anticooperativity) were determined. It was shown that non-additivity of the interaction is most strongly pronounced in the energy and vibrational frequency values, geometrical parameters of hydrogen bonds are less sensitive to the mutual influence. The anticooperative effect is more pronounced on the hydrogen bridge length R(F...F) than on the geometry of proton donor r(HF). The hydrogen bond formation and the increase of the number n of ligands lead to successive lengthening of the r(XF) bond adjacent to the hydrogen bridge. The length of an XF bond changes stronger on formation of each hydrogen bond than the HF bond length.

  3. Theoretical study on the mechanism of reactions of CX3rad radicals (X = H, F, Cl and Br) with C20H20 and C20F20 fullerenes

    NASA Astrophysics Data System (ADS)

    Ghafouri, Reza; Ektefa, Fatemeh

    2017-01-01

    We have applied density functional calculations to study the reactions CX3rad + C20H20, and CX3rad + C20F20 (X = H, F, Cl and Br) based on two pathways (H- or F-displacement and H- or F-abstraction from C20H20 and C20F20). Our results show that CH3rad radical prefers H- or F- abstraction from C20H20 and C20F20 while F-displacement is favorable for the reaction of CF3rad with the fullerenes. Exothermic characters of H- or F-abstraction with the lower potential barrier indicate that the H-abstraction will dominate the reaction CCl3rad + C20H20 while endothermic characters with high potential barrier heights for two reaction pathways of C20H20 and C20F20 with CBr3rad indicate unfavorable thermodynamically and kinetically pathways for these reactions. The exothermic reactions are proceed via reactant-like transition state while endothermic reactions will proceed via "late" and alkyl radical-like transition state, consistent with Hammond's postulate. These results are in line with the distribution of natural charges and electrostatic surface potentials (ESP) of reactants. Among these reactions, the reaction of CF3rad with C20F20 is most favorable both thermodynamically and kinetically which indicate that reaction of CF3rad with C20F20 and C20H20 is more favorable than CCl3rad and CBr3rad radicals.

  4. An x-ray photoemission electron microscopy study of the formation of Ti-Al phases in 4 mol% TiCl3 catalyzed NaAlH4 during high energy ball milling

    NASA Astrophysics Data System (ADS)

    Dobbins, Tabbetha; Abrecht, Mike; Uprety, Youaraj; Moore, Kristan

    2009-05-01

    This study reports reaction pathways to form TiAlx metallic complexes during the high energy ball milling of 4 mol% TiCl3 with NaAlH4 powders determined using local structure analysis of Tix+ and Alx+ species. Using x-ray photoemission electron microscopy (XPEEM) and x-ray diffraction (XRD), the oxidation state of Alx+ and Tix+ and the crystalline compounds existing in equilibrium with NaAlH4 were tracked for samples milled for times of 0 (i.e. mixing), 5, and 25 min. XPEEM analysis of the Al K edge after 5 min of milling reveals that Al remains in the 3+ oxidation state (i.e. in NaAlH4) around Ti0-rich regions of the sample. After 25 min of high energy milling, Ti0 has reacted with Al3+ (in nearby NaAlH4) to form TiAlx complexes. This study reports the pathway for TiAlx complex formation during milling of 4 mol% TiCl3 catalyzed NaAlH4 to be as follows: (1) Ti3+ reduces to Ti0 (with Al3+ near Ti0 regions) and (2) Ti0 reacts with Al3+ in NaAlH4 to form TiAlx complexes.

  5. Performance assessment of MCM-48 ceramic composite membrane by separation of AlCl3 from aqueous solution.

    PubMed

    Kumar Basumatary, Ashim; Kumar Ghoshal, Aloke; Pugazhenthi, G

    2016-12-01

    Three dimensional ordered mesoporous MCM-48 membrane was fabricated on a circular shaped ceramic support by in-situ hydrothermal method. The synthesized MCM-48 powder and MCM-48 ceramic composite membrane were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM). The porosity and pore size of the composite membrane are reduced considerably by the deposition of MCM-48 on the support. The formation of MCM-48 is verified by the XRD analysis. Three stepwise mechanisms for surfactant removal are observed by TGA analysis. FESEM images clearly signify the deposition of MCM-48 on the ceramic support. The pure water flux of the support and MCM-48 composite membrane is found to be 3.63×10(-6) and 4.18×10(-8)m(3)/m(2)skPa, respectively. The above prepared MCM-48 ceramic composite membrane is employed for the removal of AlCl3 from aqueous solution and the highest rejection of 81% is obtained at an applied pressure of 276kPa with salt concentration of 250ppm.

  6. Catalytic dehydration of carbohydrates suspended in organic solvents promoted by AlCl3 /SiO2 coated with choline chloride.

    PubMed

    Yang, Jie; De Oliveira Vigier, Karine; Gu, Yanlong; Jérôme, François

    2015-01-01

    We show that the coating of choline chloride on silica-supported AlCl3 allows the dehydration of carbohydrates to successfully proceed in low boiling point organic solvents. The concept is based on the in situ formation of a deep eutectic liquid phase on the catalyst surface, thus facilitating the interaction between the solid catalyst and insoluble carbohydrate.

  7. Synthesis and Characterization of AlCl3 Impregnated Molybdenum Oxide as Heterogeneous Nano-Catalyst for the Friedel-Crafts Acylation Reaction in Ambient Condition.

    PubMed

    Jadhav, Arvind H; Chinnappan, Amutha; Hiremath, Vishwanath; Seo, Jeong Gil

    2015-10-01

    Aluminum trichloride (AlCl3) impregnated molybdenum oxide heterogeneous nano-catalyst was prepared by using simple impregnation method. The prepared heterogeneous catalyst was characterized by powder X-ray diffraction, FT-IR spectroscopy, solid-state NMR spectroscopy, SEM imaging, and EDX mapping. The catalytic activity of this protocol was evaluated as heterogeneous catalyst for the Friedel-Crafts acylation reaction at room temperature. The impregnated MoO4(AlCl2)2 catalyst showed tremendous catalytic activity in Friedel-Crafts acylation reaction under solvent-free and mild reaction condition. As a result, 84.0% yield of acyl product with 100% consumption of reactants in 18 h reaction time at room temperature was achieved. The effects of different solvents system with MoO4(AlCl2)2 catalyst in acylation reaction was also investigated. By using optimized reaction condition various acylated derivatives were prepared. In addition, the catalyst was separated by simple filtration process after the reaction and reused several times. Therefore, heterogeneous MoO4(AlCl2)2 catalyst was found environmentally benign catalyst, very convenient, high yielding, and clean method for the Friedel-Crafts acylation reaction under solvent-free and ambient reaction condition.

  8. Pharmacogenetic diversification by alternative translation initiation: background channels to the fore: Commentary on Kisselbach et al., Br J Pharmacol 171: 5182–5194

    PubMed Central

    Abbott, G W

    2015-01-01

    Linked Article This article is a Commentary on Kisselbach J, Seyler C, Schweizer PA, Gerstberger R, Becker R, Katus HA and Thomas D (2014). Modulation of K2P2.1 and K2P10.1 K+ channel sensitivity to carvedilol by alternative mRNA translation initiation. Br J Pharmacol 171: 5182–5194. doi: 10.1111/bph.12596 PMID:24528336

  9. Effects of Si/Al Ratio on Cu/SSZ-13 NH3-SCR Catalysts: Implications for the active Cu species and the Roles of Brønsted Acidity

    SciTech Connect

    Gao, Feng; Washton, Nancy M.; Wang, Yilin; Kollar, Marton; Szanyi, Janos; Peden, Charles HF

    2015-09-03

    Cu/SSZ-13 catalysts with three Si/Al ratios of 6, 12 and 35 were synthesized with Cu incorporation via solution ion exchange. The implications of varying Si/Al ratios on the nature of the multiple Cu species that can be present in the SSZ-13 zeolite are a major focus of this work, as highlighted by the results of a variety of catalyst characterization and reaction kinetics measurements. Specifically, catalysts were characterized with surface area/pore volume measurements, temperature programmed reduction by H2 (H2-TPR), NH3 temperature programmed desorption (NH3-TPD), and DRIFTS and solid-state nuclear magnetic resonance (NMR) spectroscopies. Catalytic properties were examined using NO oxidation, ammonia oxidation, and standard ammonia selective catalytic reduction (NH3-SCR) reactions on selected catalysts under differential conditions. Besides indicating possible variably active multiple Cu species for these reactions, the measurements are also used to untangle some of the complexities caused by the interplay between redox of Cu ion centers and Brønsted acidity. All three reactions appear to follow a redox reaction mechanism, yet the roles of Brønsted acidity are quite different. For NO oxidation, increasing Si/Al ratio lowers Cu redox barriers, thus enhancing reaction rates. Brønsted acidity appears to play essentially no role for this reaction. For standard NH3-SCR, residual Brønsted acidity plays a significant beneficial role at both low- and high-temperature regimes. For NH3 oxidation, no clear trend is observed suggesting both Cu ion center redox and Brønsted acidity play important and perhaps competing roles. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of

  10. Effect of LiAlO{sub 2} nanoparticle filler concentration on the electrical properties of PEO–LiClO{sub 4} composite

    SciTech Connect

    Masoud, E.M.; El-Bellihi, A.-A.; Bayoumy, W.A.; Mousa, M.A.

    2013-03-15

    Highlights: ► Structural modification of nano LiAlO{sub 2} filler increased conductivity. ► Good ionic conductivity for (LiAlO{sub 2}){sub 1.5}(PEO){sub 11}(LiClO{sub 4}) at room temperature. ► Nano LiAlO{sub 2} filler enhanced both ion migration and orientation. ► High dielectric properties for (LiAlO{sub 2}){sub 1.5}(PEO){sub 11}(LiClO{sub 4}) at room temperature. - Abstract: Nano-composite polymer electrolytes are receiving attention as potential candidates to be used as electrolyte membranes in lithium polymer batteries and other devices. In this work, polyethylene oxide–LiClO{sub 4} based composite polymer electrolyte was prepared by solution casting method. The effect of LiAlO{sub 2} nanoparticle ceramic filler concentration on the structure and electrical conduction of the composite was studied. Nano-LiAlO{sub 2} was synthesized by sol–gel method. The samples were characterized using X-ray diffraction, Fourier Transmission-Infra Red, Differential Scanning Calorimetry, and tested by dielectric properties, Direct and Alternating current measurements as well as by impedance spectroscopy. All samples showed a behavior referring to an ionic conduction. Generally, the melting temperature of the polymer electrolyte decreased with filler concentration. Both thermal property and filler concentration influenced conductivity value. At room temperature, the highest ionic conductivity was 9.76 × 10{sup −5} ohm{sup −1} cm{sup −1} for sample with a composition of (LiAlO{sub 2}){sub 1.5}(polyethylene oxide){sub 11}(LiClO{sub 4}). All results were correlated and discussed.

  11. The current-density dependence U(J) of the activation energy for the motion of Abrikosov vortices in the organic superconductor {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl{sub 0.5}Br{sub 0.5}

    SciTech Connect

    Primenko, A.E.; Kuznetsov, V.D.; Metlushko, V.V.

    1995-02-01

    The authors have investigated the thermally activated motion of flux in the organic superconductor {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Cl{sub 0.5}Br{sub 0.5} over a wide range of current densities J, and have obtained the dependence of the activation energy U for this motion on current density. 21 refs., 2 figs.

  12. Kinetics and Mechanism of Cationic Flexible Nanoparticles (CFN) - Catalyzed Piperidinolysis of Anionic Phenyl Salicylate: CFN = TTABr/MX/H2O with MX = NaCl, NaBr; CnH2n+1CO2Na, n = 4, 5, 6 and 7.

    PubMed

    Mohd Noh, Muhammad Azri; Khalid, Khalisanni; Ariffin, Azhar; Khan, Mohammad Niyaz

    2016-01-01

    The present study is focused on the effect of the TTABr/MX/H2O-nanoparticles on the rate of piperidinolysis of ionized phenyl salicylate where TTABr represents tetradecyltrimethylammonium bromide and MX = NaCl, NaBr and CnH2n+1CO2Na with n = 4, 5, 6 and 7. Pseudo-first-order rate constant for the piperidinolysis of ionized phenyl salicylate at 35°C and constant concentration [PSa(-)]T = 0.2 mM, [Pip]T = 0.1 M, [NaOH] = 30 mM, [TTABr]T and different [MX] follow an empirical relationship which gives two empirical constant, (X)kcat and K(X/S). The value of relative counterion (X) binding constant, RX(Br) were calculated from the relationship; RX(Br) = (X)kcat/(Br)kcat. The values of RX(Br) for X = C4H9CO2(-), C5H11CO2(-), C6H13CO2(-), and C7H15CO2(-) are increasing with increase in the number of alkyl chain of counterion X.

  13. Inhibitor effects of sodium benzoate on corrosion resistance of Al6061-B4C composites in NaCl and H3BO3 solutions

    NASA Astrophysics Data System (ADS)

    Rafi-ud-din; Shafqat, Q. A.; Shahzad, M.; Ahmad, Ejaz; Asghar, Z.; Rafiq, Nouman; Qureshi, A. H.; Syed, Waqar adil; asim Pasha, Riffat

    2016-12-01

    Sodium benzoate (SB) is used for the first time to inhibit the corrosion of Al6061-B4C composites in H3BO3 and NaCl solutions. Al6061100-x -x wt% B4C (x = 0, 5, and 10) composites are manufactured by a powder metallurgy route. The corrosion inhibition efficiency of SB is investigated as a function of the volume fractions of B4C particles by using potentiodynamic polarization and electrochemical impedance techniques. Without the use of an inhibitor, an increase of the B4C particles in the composite decreases the corrosion resistance of Al6061-B4C composites. It is found that SB is an efficient corrosion inhibitor for Al6061-B4C composites in both investigated solutions. The corrosion inhibition efficiency of SB increases with an increase in B4C content. Since SB is an adsorption type inhibitor, it is envisaged that an extremely thin layer of molecules adsorbs onto the surface and suppresses the oxidation and reduction. It is found that the inhibitor effect of SB is more pronounced in a H3BO3 environment than in NaCl solution. Further, the mechanism of corrosion inhibition by SB is illustrated by using optical and scanning electron microscopy of corroded samples. It is found that the adsorption of benzoate ions on the Al surface and its bonding with Al3+ ions forms a hydrophobic layer on top of the exposed Al surface, which enhances the protection against dissolved boride ions.

  14. Computational study of the equilibrium geometry and anharmonic vibrational spectra of PbX2 ··· NO and PbX2 ··· ON (X = F, Cl, Br, I) complexes

    NASA Astrophysics Data System (ADS)

    Kowal, Andrzej T.

    2010-06-01

    Equilibrium geometry parameters of the open shell PbX2 ... NO and PbX2 ... ON (X = F, Cl, Br, I) complexes have been computed by second-order Z-averaged perturbation theory (ZAPT2) with Stevens-Basch-Krauss-Jasien-Cundari (SBKJC) scalar-relativistic effective core potentials (RECP) and basis sets on all atoms. Equilibrium geometries of both PbX2 ... NO and PbX2 ... ON bonding isomers conform to Cs symmetry structure with end-on ligand coordination, and are characterized by Pb-N bond length within 266.6-271.7 pm range, Pb-O distance of 267.8-275.8 pm, Pb-N-O angle within 109.2-120.7° range, and Pb-O-N angle of 117.1-127.8°. Anharmonic vibrational spectra of the PbX2 ... NO and PbX2 ... ON complexes have been calculated by direct correlation-corrected vibrational self-consistent field (CC-VSCF) method enhanced with second-order perturbative correction using potential energy surfaces (PESs) determined at ZAPT2/SBKJC+(d) level in curvilinear (internal) coordinates. Fundamental ν(Pb-N) stretching mode has been computed at 232.8 to 209.0 cm-1 within PbX2 ... NO series. whereas ν(Pb-O) stretching mode fundamental evaluation in PbX2 ... ON series afforded wavenumbers within 183.2-150.7 cm-1 range. Blue shift of the ν(N=O) stretching mode wavenumber upon PbX2 ... NO complex formation, computed in anharmonic approximation, 15.8-14.6 cm-1, correctly reproduces the effect observed in the low-temperature Ar matrix spectra of PbX2 ... NO compounds. Influence of complex formation on the νs(Pb-X) and νas(Pb-X) fundamentals of PbX2 halides has also been discussed. Two-dimensional mapping of the ? (Qi , Qj ) mode-mode coupling potential has been used to rationalize the origin of mode coupling related anharmonic corrections.

  15. Memory-enhancing effect of aspirin is mediated through opioid system modulation in an AlCl3-induced neurotoxicity mouse model

    PubMed Central

    RIZWAN, SAIMA; IDREES, AYESHA; ASHRAF, MUHAMMAD; AHMED, TOUQEER

    2016-01-01

    Neurodegenerative disorders such as Alzheimers disease (AD) are multifaceted and there are currently a limited number of therapeutic strategies available to treat them. Aspirin is known to act on multiple therapeutic targets and is a successful anti-inflammatory agent in various tissues. The present study aimed to ascertain the performance of aspirin when employed as a therapeutic agent to treat neurodegeneration on novel targets, including opioid system genes, in an AlCl3-induced neurotoxicity mouse model. The effects of two doses of aspirin (5 and 20 mg/kg aspirin for 12 days) were investigated in an AlCl3-induced neurotoxicity mouse model (150 mg/kg AlCl3 for 12 days). Neurological improvements were assessed through different behavioral tests and the effects of aspirin on opioid system gene expression levels were assessed by reverse transcription-polymerase chain reaction. Both doses resulted in improvements in cognitive behavior. A 5 mg/kg dose of aspirin was revealed to be effective for spatial memory improvement (7.14±0.84 sec), whilst a 20 mg/kg dose was superior for improving extinction learning (7.63±4.04%). Aspirin (5 mg/kg) also significantly improved contextual memory (48.05±10.6%) when compared with the AlCl3-treated group (1.49±0.62%; P<0.001). Aspirin was also observed to significantly decrease δ-opioid receptor expression in the cortex (1.09±0.08 and 1.27±0.08, respectively) at both doses (5 and 20 mg/kg) when compared with the AlCl3-treated group (3.69±1.43; P<0.05). Furthermore, aspirin at 5 mg/kg significantly reduced expression of prodynorphin in the cortex (0.57±0.20) when compared with the AlCl3-treated group (1.95±0.84; P<0.05). Notably, the effect of aspirin was significant in the cortex but not in the hippocampus. In summary, aspirin was effective in ameliorating the AD-like symptoms via the modulation of opioid systems. However, additional studies are required to determine the long term effects of aspirin on such conditions. PMID

  16. The mechanism of oxide whisker growth and hot corrosion of hot-dipped Al-Si coated 430 stainless steels in air-NaCl (g) atmosphere

    NASA Astrophysics Data System (ADS)

    Liu, Hsiao-Hung; Cheng, Wei-Jen; Wang, Chaur-Jeng

    2011-10-01

    The mechanisms of oxide whisker growth and hot corrosion of 430 stainless steel (430SS) and aluminide 430 stainless steel hot-dipped in a Al-10 wt.%Si molten bath (430HDAS) were studied at 750 and 850 °C in air mixed with 500 and 990 vppm NaCl (g). The results showed that the loose Cr 2O 3 scale which formed on the 430SS could not prevent the corrosion of 430SS in a 500 vppm NaCl (g) atmosphere, resulting in the formation of Fe 2O 3 scale. Fe 2O 3 whiskers grew at the grain boundary of the Fe 2O 3 scale. However, no Fe 2O 3 whiskers formed on the Fe 2O 3 scale while 430SS was exposed in a 900 vppm NaCl (g) atmosphere. During the initial high-temperature corrosion of 430HDAS in a 500 vppm NaCl (g) atmosphere, a dense Al 2O 3 scale formed on the surface of the specimens. Also, Al 2O 3 whiskers grew on the Al 2O 3 scale. As exposure time increased, cyclic chlorination/oxidation degraded the protective aluminide layer and caused the formation of Fe 2O 3 scale and Fe 2O 3 whiskers. The morphology of Fe 2O 3 whiskers formed at 750 °C is more slender than those formed at 850 °C. The formation and growth of both Fe 2O 3 and Al 2O 3 whiskers may be attributed to the chloridation of both the steel substrate and aluminide layer, accelerating the diffusion rate of metallic ions in the oxide scales.

  17. Cs{sub 7}Sm{sub 11}[TeO{sub 3}]{sub 12}Cl{sub 16} and Rb{sub 7}Nd{sub 11}[TeO{sub 3}]{sub 12}Br{sub 16}, the new tellurite halides of the tetragonal Rb{sub 6}LiNd{sub 11}[SeO{sub 3}]{sub 12}Cl{sub 16} structure type

    SciTech Connect

    Charkin, Dmitri O.; Black, Cameron; Downie, Lewis J.; Sklovsky, Dmitry E.; Berdonosov, Peter S.; Olenev, Andrei V.; Zhou, Wuzong; Lightfoot, Philip; Dolgikh, Valery A.

    2015-12-15

    Two new rare-earth – alkali – tellurium oxide halides were synthesized by a salt flux technique and characterized by single-crystal X-ray diffraction. The structures of the new compounds Cs{sub 7}Sm{sub 11}[TeO{sub 3}]{sub 12}Cl{sub 16} (I) and Rb{sub 7}Nd{sub 11}[TeO{sub 3}]{sub 12}Br{sub 16} (II) (both tetragonal, space group I4/mcm) correspond to the sequence of [MLn{sub 11}(TeO{sub 3}){sub 12}] and [M{sub 6}X{sub 16}] layers and bear very strong similarities to those of known selenite analogs. We discuss the trends in similarities and differences in compositions and structural details between the Se and Te compounds; more members of the family are predicted. - Graphical abstract: Two new rare-earth – alkali – tellurium oxide halides were predicted and synthesized. - Highlights: • Two new rare-earth – alkali – tellurium oxide halides were synthesized. • They adopt slab structure of rare earth-tellurium-oxygen and CsCl-like slabs. • The Br-based CsCl-like slabs have been observed first in this layered family.

  18. Performance of Al-0.5 Mg-0.02 Ga-0.1 Sn-0.5 Mn as anode for Al-air battery in NaCl solutions

    NASA Astrophysics Data System (ADS)

    Ma, Jingling; Wen, Jiuba; Gao, Junwei; Li, Quanan

    2014-05-01

    In this research, metal-air battery based on Al, Zn, Al-0.5 Mg-0.02 Ga-0.1 Sn and Al-0.5 Mg-0.02 Ga-0.1 Sn-0.5 Mn (wt%) is prepared and the battery performance is investigated by constant current discharge test in 2 mol L-1 NaCl solutions. The characteristics of the anodes after discharge are investigated by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM). The corrosion behavior of the anodes is studied by self-corrosion rate measurement and potentiodynamic polarization measurement. The results show that Al-Mg-Ga-Sn-Mn is more active than Al, Zn and Al-Mg-Ga-Sn anodes. The self-corrosion rate is found to be in the order: Al < Al-Mg-Ga-Sn-Mn < Al-Mg-Ga-Sn < Zn. It has been observed that the Al-air battery based on Al-Mg-Ga-Sn-Mn offers higher operating voltage and anodic utilization than those with others. SEM and EIS results of the alloy are in good agreement with corrosion characteristics.

  19. Novel layered hybrid fluoroaluminate in the composition space diagram of the Al(OH)3-HguaCl-HF(aq)-EtOH system.

    PubMed

    Adil, Karim; Le Bail, Armel; Leblanc, Marc; Maisonneuve, Vincent

    2010-03-01

    A composition space diagram is used to establish the stability regions of hybrid fluoroaluminates synthesized by solvothermal reactions in the Al(OH)(3)-HguaCl-HF(aq)-EtOH system. The syntheses are conducted using microwave heating at 190 degrees C for 1 h. The structures of two new guanidinium fluoroaluminates, (H(3)O)(2) x [Hgua](16) x (Al(4)F(18))(3) x H(2)O and [Hgua](2) x (Al(5)F(17)), are reported. (H(3)O)(2) x [Hgua](16) x (Al(4)F(18))(3) x H(2)O, determined from single-crystal X-ray data, consists of discrete (Al(4)F(18))(6-) polyanions, while [Hgua](2) x (Al(5)F(17)), solved from powder X-ray diffraction data in direct space, contains unprecedented Al(5)F(17) layers constructed from the intergrowth of HTB and perovskite columns. A disorder of H(2)O and H(3)O(+) is evidenced in (H(3)O)(2) x [Hgua](16) x (Al(4)F(18))(3) x H(2)O together with a disorder of guanidinium cations in the interlayer space of [Hgua](2) x (Al(5)F(17)).

  20. Investigation on luminescence properties of Eu2+-doped Ba3Al2O5Cl2 phosphor for near-UV-excited white LEDs.

    PubMed

    Pawade, V B; Dhoble, S J

    2012-01-01

    Ba3Al2O5Cl2:Eu(2+) phosphor was prepared by combustion synthesis (CS). The prepared phosphor was excited at 329 nm; the phosphors shows an efficient bluish-green wide-band emission centred at 490 nm, which originates from the 4f(6)d(1)  →  4f(7) transition of Eu(2+) ions. The excitation spectra of the phosphors have a band centred at 329 nm. It was also characterized by XRD, FT-IR for confirmation of phase purity, and FT-IR analysis indicated the vibrations of metal-oxygen (M-O) groups. SEM shows the morphology of the phosphor at the submicron scale. The results indicate that Ba3Al2O5Cl2:Eu(2+) phosphor may be applicable for solid-state lighting purposes.

  1. Phase behavior and physicochemical properties of sodium octyl sulfate/n-decane/1-hexanol/aqueous AlCl[sub 3] middle-phase microemulsion

    SciTech Connect

    Abe, Masahiko; Yamazaki, Tadao; Ogino, Keizo )

    1992-03-01

    The phase behavior and physicochemical properties of sodium octyl sulfate/n-decane/1-hexanol/aqueous AlCl[sub 3] middle-phase microemulsion have been studied as a function of salinity to develop an experimental investigation for better understanding of the microstructure of a middle-phase microemulsion. The system exhibits a Winsor-type phase transition (Winsor I [leftrightarrow] Winsor III [leftrightarrow] Winsor II) with increasing salinity. Over an appreciable salinity (from 0.50% to 9.2%), the formation of Winsor III, composed of a middle-phase microemulsion in equilibrium with the excess water and oil phases, was observed. It has been observed that as the salinity is increased, the phase volume of the middle-phase microemulsion undergoes a drastic decrease at a specific brine concentration (3.8%). Furthermore, the physicochemical properties such as water content, electrical conductivity, diffusion coefficient, and solubilization of 1-hexanol in the AlCl[sub 3] middle-phase microemulsion all show abrupt changes at this salinity. The drastic change in the phase volume and physicochemical properties at the specific salinity of 3.8% may be attributed to a phase inversion of the AlCl[sub 3] middle-phase microemulsion from oil-rich to water-rich continuous phase with increasing AlCl[sub 3] concentration, which is quite a different behavior from that observed for monovalent and divalent salt systems. Specifically, it may be assumed that a fluctuating structure of bicontinuous type and a liquid crystal structure overcome the droplet structure in the phase equilibrium at a certain salinity during the increase in the trivalent salt concentration. 25 refs., 10 figs.

  2. Synthesis and crystal structure of chlorate-enclathrated in aluminogermanate sodalite Na8[AlGeO4]6(ClO3)2

    NASA Astrophysics Data System (ADS)

    Borhade, Ashok V.; Dholi, Arun G.

    2013-04-01

    Encapsulation of chlorate in sodalite with aluminogermanate host framework has been obtained by one pot hydrothermal synthesis at 393 K. The crystal structure of Na8[AlGeO4]6(ClO3)2; sodalite was refined from X-ray powder data in the space group Pbar 43 n: a = 9.169 Å, where Al-O-Ge angle is 137.6°. The 27Al MAS NMR study confirmed alternate Ge and Al ordering of the sodalite framework, while 23Na gave insight into the structure and dynamics of the cage fillings. Infrared spectrum confirmed the encapsulation of chlorate as well as the framework formation of aluminogermanate sodalite. SEM study showed the retention of cubical morphology of the aluminogermanate sodalite. Thermogravimetric analysis provided information on the extent of chlorate entrapment, stability within the sodalite cages and decomposition properties.

  3. Removal of Tin and Copper from Liquid Iron by Al2O3-Saturated Ca-CaCl2 Slags at 1448 to 1648 K

    NASA Astrophysics Data System (ADS)

    Ghosh, Dinabandhu

    2009-08-01

    The removal of tin and copper from liquid iron by Al2O3-saturated Ca-CaCl2 slags was carried out in separate alumina crucibles at 1448 to 1648 K that showed small partition ratios of less than 1. The tin content of the liquid iron typically decreased from its initial value of 50 to 40 wt pct and the (gross) copper content of the iron-copper mixture from 50 to 45 wt pct, at equilibrium. The small refining efficiencies (37 pct, maximum) of the slags, the initial composition of which were, in most cases, Ca-50 wt pct CaCl2, may be attributed to the significant dissolution in them of alumina, up to 42.0 wt pct (29.6 mol pct), in experiments with Sn, and up to 54.4 wt pct (38.6 mol pct), in experiments with Cu. Treating Ca as the solvent, a number of interaction coefficients such as \\varepsilon_{{{text{Al}}_{ 2} {text{O}}_{ 3} }}^{{{text{Al}}_{ 2} {text{O}}_{ 3} }} , \\varepsilon_{{{text{Al}}_{ 2} {text{O}}_{ 3} }}^{{{text{CaCl}}_{ 2} }} , \\varepsilon_{{{text{Al}}_{ 2} {text{O}}_{ 3} }}^{text{Sn}} , \\varepsilon_{{{text{CaCl}}_{ 2} }}^{{{text{CaCl}}_{ 2} }} , \\varepsilon_{{{text{CaCl}}_{ 2} }}^{text{Sn}} , and \\varepsilon_{text{Sn}}^{text{Sn}} as well as the activity coefficient γ_{{{text{Al}}_{ 2} {text{O}}_{ 3} }}0 were all determined at 1448 K. The activity of Ca (relative to pure liquid Ca) was obtained as approximately 0.65 to 0.75 in the system. Further, the two partial molar mixing/excess properties of alumina bar{H}_{{{text{Al}}_{ 2} {text{O}}_{ 3} }}M and bar{S}_{{{text{Al}}_{ 2} {text{O}}_{ 3} }}^{XS} in the alumina-saturated Ca-17 pct CaCl2- 37 pct Al2O3 (molar basis) slag were evaluated and found to be -118.3(±10.8) kJ/mol and -0.062(±0.007) kJ/K·mol, respectively, at 1448 to 1648 K. In addition, in view of the reported success of CaC2 as a refining agent, some experiments were carried out with CaC2-CaF2 mixtures in alumina, magnesia, and graphite crucibles at 1873 K, to remove tin from liquid Fe-2 wt pct Sn. However, alumina and magnesia crucibles

  4. Ozone Depletion Potential of CH3Br

    NASA Technical Reports Server (NTRS)

    Sander, Stanley P.; Ko, Malcolm K. W.; Sze, Nien Dak; Scott, Courtney; Rodriquez, Jose M.; Weisenstein, Debra K.

    1998-01-01

    The ozone depletion potential (ODP) of methyl bromide (CH3Br) can be determined by combining the model-calculated bromine efficiency factor (BEF) for CH3Br and its atmospheric lifetime. This paper examines how changes in several key kinetic data affect BEF. The key reactions highlighted in this study include the reaction of BrO + H02, the absorption cross section of HOBr, the absorption cross section and the photolysis products of BrON02, and the heterogeneous conversion of BrON02 to HOBR and HN03 on aerosol particles. By combining the calculated BEF with the latest estimate of 0.7 year for the atmospheric lifetime of CH3Br, the likely value of ODP for CH3Br is 0.39. The model-calculated concentration of HBr (approximately 0.3 pptv) in the lower stratosphere is substantially smaller than the reported measured value of about I pptv. Recent publications suggested models can reproduce the measured value if one assumes a yield for HBr from the reaction of BrO + OH or from the reaction of BrO + H02. Although the DeAlore et al. evaluation concluded any substantial yield of HBr from BrO + HO2 is unlikely, for completeness, we calculate the effects of these assumed yields on BEF for CH3Br. Our calculations show that the effects are minimal: practically no impact for an assumed 1.3% yield of HBr from BrO + OH and 10% smaller for an assumed 0.6% yield from BrO + H02.

  5. Is the 'Bromine Explosion' generated from the reaction BrO HO2 alone?

    NASA Astrophysics Data System (ADS)

    Behnke, Wolfgang; Zetzsch, Cornelius

    2010-05-01

    We observed bromine explosions (a fast production of atomic Br and Cl under tropospheric conditions) in various smog chamber experiments in Teflon bags at room temperature at a relative humidity of about 80% in the presence of NaCl/NaBr-aerosol, simulated sunlight and ozone (200 - 400 ppb). Time profiles of ozone and hydrocarbons (HCs: n-butane, 2,2-dimethylbutane, tetramethylbutane and toluene, initially about 2 ppb each) were monitored to determine concentrations and source strengths of OH radicals, atomic Cl and Br and the corresponding time profiles of BrCl and Br2 as their photolytic precursors. The number and size of aerosols are measured as well as their chemical composition (Br-, Cl- and oxalic acid). Full records of raw data from the smog chamber runs are available at www.eurochamp.org for potential users. Chemical box model calculations deliver concentrations of various intermediates, such as aldehydes, HO2 and RO2 radicals and the inorganic halogen compounds ClO, BrO, HOCl and HOBr, where HOBr from O3 + Br- => BrO- + O2 in the aqueous/adsorbed phase induces the following gas-phase/ heterogeneous chain reaction Br + O3 => BrO + O2(1) BrO + HO2 => HOBr + O2(2a) HOBr + (Aerosol) => HOBrad(3) Surface-adsorbed HOBr reacts with Br- or Cl- to produce Br2 or BrCl, both of which are released and photolysed. Formation of Br2 should prevail up to Cl-/Br- -ratios of about 104 (Fickert, S., J.W. Adams, J.N. Crowley, J. Geophys. Res., D104, 23719-23727, 1999). A maximum of this ratio is reached about 30 minutes after the beginning and decreases during the next hours - probably by reaction of Br2 with oxalate and absorption of HBr, formed from the reaction of Br with aldehydes. Parallel to chain reaction (1)-(3) a chain reaction replacing Br by Cl seems possible but can not be realized, since the main sink of atomic Cl is its reaction with hydrocarbons - leading to chain termination - in contrast to atomic Br (ratio of rates: kCl[O3]/kCl[HC] ~ 0.1; kBr[O3]/kBr

  6. Kinetics of NiO and NiCl2 Hydrogen Reduction as Precursors and Properties of Produced Ni/Al2O3 and Ni-Pd/Al2O3 Catalysts

    PubMed Central

    Sokić, Miroslav; Kamberović, Željko; Nikolić, Vesna; Marković, Branislav; Korać, Marija; Anđić, Zoran; Gavrilovski, Milorad

    2015-01-01

    The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl2 reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al2O3 catalysts. The effect of temperature and time on NiO and NiCl2 reduction degrees was studied. Avrami I equation was selected as the most favorable kinetic model and used to determine activation energy of the NiO and NiCl2 reduction for the investigated temperature range (623–923 K) and time intervals (1–5 minutes). The investigation enabled reaching conclusions about the reaction ability and rate of the reduction processes. Afterward, Ni/Al2O3 catalysts were obtained by using oxide and chloride precursor for Ni. The catalysts were supported on alumina-based foam and prepared via aerosol route. Properties of the samples before and after low-temperature hydrogen reduction (633 K) were compared. Obtained results indicated that the synthesis of Ni/Al2O3 catalysts can be more efficient if chloride precursor for Ni is directly reduced by hydrogen during the synthesis process, without the calcination step. In addition, Ni-Pd/Al2O3 catalysts with different metal content were prepared by using chloride precursors. Lower reduction temperature was utilized and the chlorides were almost completely reduced at 533 K. PMID:25789335

  7. Molecular dynamics simulations of nonpolarizable inorganic salt solution interfaces: NaCl, NaBr, and NaI in transferable intermolecular potential 4-point with charge dependent polarizability (TIP4P-QDP) water

    PubMed Central

    Bauer, Brad A.; Patel, Sandeep

    2010-01-01

    We present molecular dynamics simulations of the liquid-vapor interface of 1M salt solutions of nonpolarizable NaCl, NaBr, and NaI in polarizable transferable intermolecular potential 4-point with charge dependent polarizability water [B. A. Bauer , J. Chem. Theory Comput. 5, 359 (2009)]; this water model accommodates increased solvent polarizability (relative to the condensed phase) in the interfacial and vapor regions. We employ fixed-charge ion models developed in conjunction with the TIP4P-QDP water model to reproduce ab initio ion-water binding energies and ion-water distances for isolated ion-water pairs. The transferability of these ion models to the condensed phase was validated with hydration free energies computed using thermodynamic integration (TI) and appropriate energy corrections. Density profiles of Cl−, Br−, and I− exhibit charge layering in the interfacial region; anions and cation interfacial probabilities show marked localization, with the anions penetrating further toward the vapor than the cations. Importantly, in none of the cases studied do anions favor the outermost regions of the interface; there is always an aqueous region between the anions and vapor phase. Observed interfacial charge layering is independent of the strength of anion-cation interactions as manifest in anion-cation contact ion pair peaks and solvent separated ion pair peaks; by artificially modulating the strength of anion-cation interactions (independent of their interactions with solvent), we find little dependence on charge layering particularly for the larger iodide anion. The present results reiterate the widely held view of the importance of solvent and ion polarizability in mediating specific anion surface segregation effects. Moreover, due to the higher parametrized polarizability of the TIP4P-QDP condensed phase {1.31 Å3 for TIP4P-QDP versus 1.1 Å3 (TIP4P-FQ) and 0.87 Å3 (POL3) [Ponder and Case, Adv. Protein Chem. 66, 27 (2003)]} based on ab initio

  8. Inductively coupled plasma–reactive ion etching of c- and a-plane AlGaN over the entire Al composition range: Effect of BCl{sub 3} pretreatment in Cl{sub 2}/Ar plasma chemistry

    SciTech Connect

    Shah, Amit P.; Laskar, Masihhur R.; Azizur Rahman, A.; Gokhale, Maheshwar R.; Bhattacharya, Arnab

    2013-11-15

    Inductively coupled plasma (ICP)–reactive ion etching (RIE) patterning is a standard processing step for UV and optical photonic devices based on III-nitride materials. There is little research on ICP-RIE of high Al-content AlGaN alloys and for nonpolar nitride orientations. The authors present a comprehensive study of the ICP-RIE of c- and a-plane AlGaN in Cl{sub 2}/Ar plasma over the entire Al composition range. The authors find that the etch rate decreases in general with increasing Al content, with different behavior for c- and a-plane AlGaN. They also study the effect of BCl{sub 3} deoxidizing plasma pretreatment. An ICP deoxidizing BCl{sub 3} plasma with the addition of argon is more efficient in removal of surface oxides from Al{sub x}Ga{sub 1−x}N than RIE alone. These experiments show that Al{sub x}Ga{sub 1−x}N etching is affected by the higher binding energy of AlN and the higher affinity of oxygen to aluminum compared to gallium, with oxides on a-plane AlGaN more difficult to etch as compared to oxides on c-plane AlGaN, specifically for high Al composition materials. The authors achieve reasonably high etch rate (∼350 nm/min) for high Al-content materials with a smooth surface morphology at a low DC bias of ∼−45 VDC.

  9. Solubility of corundum and quartz in the system Al2O3-SiO2-NaCl-H2O at deep-crustal metamorphic conditions: 800 ° C and 10 kbar

    NASA Astrophysics Data System (ADS)

    Newton, R. C.; Manning, C. E.

    2004-12-01

    The solubility of corundum in H2O-NaCl-SiO2 fluids has been measured at 800 ° C and 10 kbar. Solubility was determined by weight loss after equilibration of polished single crystals of synthetic corundum with fluids in welded Pt envelopes. Fluid compositions were XNaCl=0 to 0.5 and SiO2 up to quartz saturation at a given XNaCl. The experiments were 1 to 7 days duration in 1.91-cm-diameter piston-cylinder apparatus with NaCl pressure medium. Kyanite and sillimanite are slightly more stable than quartz + corundum at these P-T conditions, but did not appear. The solubility in initially pure H2O is very small: mAl2O3 (mol Al2O3/kg H2O) = 0.00135, but increases rapidly as the fourth root of XNaCl to 0.01 at XNaCl=0.1 and 0.015 at halite saturation (XNaCl\\sim0.6). Quenched solutions were pH neutral. The data were modeled with simple mixing models involving NaAl(OH)_{4}, Al(OH)_{3}, and any of their several dehydration and dissociation products, as well as Na^{+}, Cl^{-}, and H_{2}O. The best-fit reactions are: X_{NaCl}$<0.3: Al2O3(cr) + Na+ + H2O = NaAlO(OH)2 + AlO+ XNaCl>0.3: Al2O3(cr) + Na+ = NaAlO2 + AlO+ Silica in solution further amplifies NaCl-enhancement of corundum solubility. Al2O3 molality at metastable quartz saturation rises rapidly from 0.006 at XNaCl=0, to 0.038 at XNaCl=0.1, and then more gradually to 0.045 at XNaCl=0.3. Quenched solutions from SiO2- and NaCl-rich compositions are acid (pH ˜1). The dissolution reaction, assuming a neutral NaAlSi species, must therefore be similar to: Al2O3(cr) + 2Na+ + xSi(OH)4 = 2NaAl Six/2Ox/2+y(OH)x-2y+4) + (x+2y-5)H2O + 2H+. Simple-mixing modeling suggests that the average Si/Al ratio (x/2) and number of non-bridging O2- (y) of the dominant Al solute species at 0.03≤XNaCl≤0.6 and quartz saturation are given by the formula: NaAlSi2.75O6.38(OH)2.24, close to the NaAlSi3O8-H2O join. Small amounts of spherical globules of aluminosilicate glass appeared close to quartz saturation at XNaCl≥0.1 It was not proven in

  10. The effect of glycerol on properties of chitosan/poly(vinyl alcohol) films with AlCl3·6H2O aqueous solution as the solvent for chitosan.

    PubMed

    Jiang, Xiancai; Zhao, Yulai; Hou, Linxi

    2016-01-01

    The AlCl3·6H2O aqueous solution was used to dissolve chitosan (CS) and the CS/poly(vinyl alcohol) (PVA) blend films were prepared at the absence of acetic acid. AlCl3·6H2O was retained in CS/PVA film and glycerol was added to form the complex plasticizer with AlCl3·6H2O. The effect of glycerol on the water sorption, crystalline, thermal and mechanical properties of AlCl3·6H2O doped CS/PVA film was studied by atomic force microscopy, X-ray diffraction, thermal gravity analysis and tensile testing, respectively. The experimental results showed that glycerol had a significant positive effect on the properties of AlCl3·6H2O doped CS/PVA films. With the synergism effect of AlCl3·6H2O and glycerol, the prepared CS/PVA films showed excellent mechanical properties. With the addition of 30wt% glycerol, the AlCl3·6H2O doped CS/PVA films behave the tensile strength of 39MPa and elongation at break of 120%, respectively.

  11. Properties of {sup 20}Na, {sup 24}Al, {sup 28}P, {sup 32}Cl, and {sup 36}K for studies of explosive hydrogen burning

    SciTech Connect

    Wrede, C.; Clark, J. A.; Deibel, C. M.; Faestermann, T.; Parikh, A.; Bishop, S.; Eppinger, K.; Kruecken, R.; Lepyoshkina, O.; Rugel, G.; Hertenberger, R.; Wirth, H.-F.; Chen, A. A.; Freeman, B. M.; Setoodehnia, K.

    2010-09-15

    The radiative proton-capture reactions {sup 19}Ne(p,{gamma}){sup 20}Na, {sup 23}Mg(p,{gamma}){sup 24}Al, {sup 27}Si(p,{gamma}){sup 28}P, {sup 31}S(p,{gamma}){sup 32}Cl, and {sup 35}Ar(p,{gamma}){sup 36}K potentially influence energy generation and/or nucleosynthesis during explosive hydrogen burning in classical novae and/or type I x-ray bursts. The thermonuclear rates of these reactions are dependent on resonance energies E{sub r}=E{sub x}-Q and strengths {omega}{gamma}. The {sup 20}Ne({sup 3}He,t){sup 20}Na, {sup 24}Mg({sup 3}He,t){sup 24}Al, {sup 28}Si({sup 3}He,t){sup 28}P, {sup 32}S({sup 3}He,t){sup 32}Cl, and {sup 36}Ar({sup 3}He,t){sup 36}K reactions have been measured using a 32-MeV, {sup 3}He{sup 2+} beam; ion-implanted carbon-foil targets developed at the University of Washington; and the Munich Q3D magnetic spectrograph. This experiment has already yielded precision mass measurements of {sup 20}Na, {sup 24}Al, {sup 28}P, and {sup 32}Cl [C. Wrede et al., Phys. Rev. C 81, 055503 (2010)], which are used presently to constrain the corresponding (p,{gamma}) reaction Q values. The new {sup 24}Al and {sup 28}P masses resolve a discrepancy in the energy of the lowest-energy resonance in the {sup 23}Mg(p,{gamma}){sup 24}Al reaction and better constrain a direct measurement of its strength. Excitation energies in {sup 32}Cl and {sup 36}K have also been measured. An important new proton-unbound level has been found at E{sub x}=2196.9(7) keV in {sup 36}K and the uncertainties in {sup 36}K excitation energies have been reduced by over an order of magnitude. Using the new data on {sup 36}K, the A=36, T=1 triplets have been reassigned. The thermonuclear {sup 35}Ar(p,{gamma}){sup 36}K reaction rate is found to be much higher than a commonly adopted rate and this could affect energy generation in type I x-ray bursts.

  12. Influence of SiC reinforcement particles on the tribocorrosion behaviour of Al-SiCp FGMs in 0.05M NaCl solution

    NASA Astrophysics Data System (ADS)

    Vieira, A. C.; Rocha, L. A.; Mischler, S.

    2011-05-01

    The main aim of this work was to study and understand the influence of SiC particles on the corrosion and tribocorrosion of Al-matrix composite materials. For that, Al-SiCp functionally graded composites were produced by centrifugal casting and different SiCp contents were achieved. Their mechanical properties were improved by age-hardening heat treatments. The tribocorrosion behaviour was studied in 0.05M NaCl solutions using a reciprocating motion tribometer involving an alumina ball sliding against the Al-based samples. Above critical SiC particles' content the matrix alloy surface was found to be protected against wear by SiC particles protruding from the surface. Below this threshold content, the SiC reinforcement was inefficient and the wear rate of the composite was the same as the non-reinforced alloy.

  13. Photoabsorption of the ground state of Ne and of Ne-like Na+, Mg2+, Al3+, Si4+, P5+, S6+, and Cl7+ ions

    NASA Astrophysics Data System (ADS)

    Sakho, I.

    2016-03-01

    Photoabsorption of the 1s2 2s2 2p6 (1S0) ground state of Ne-like ions is presented in this paper. Resonance energies and width of the 2 s 2p6 n p1P1 series of Ne and Ne-like Na+, Mg2+, Al3+, Si4+, P5+, S6+, and Cl7+ ions are reported. Wavelengths of the 2s2 2p6 (1S0) → 2s2 2p5(2P 3 / 2 , 1 / 2) n d transitions in neon-like Na+ ion and of the 2s2 2p6(1S0) → 2 s 2p6 n p1P1 transitions in Ne and in Ne-like Na+, Mg2+, Al3+, Si4+, P5+, S6+, and Cl7+ ions are tabulated. Analysis of the resonances investigated is done in the framework of the LS, jj and JK coupling schemes. All the calculations are made using the Screening constant by unit nuclear charge (SCUNC) formalism. Very good agreement is found between the SCUNC results and various experimental and theoretical literature values and new data for the Ne-like Si4+, P5+, S6+, and Cl7+ ions are listed.

  14. Solid chemistry of the Zn{sup II}/1,2,4-triazolate/anion system: Separation of 2D isoreticular layers tuned by the terminal counteranions X (X=Cl{sup -}, Br{sup -}, I{sup -}, SCN{sup -})

    SciTech Connect

    Chen Sanping; Sun Shu; Gao Shengli

    2008-12-15

    An array of 2D isoreticular layers, viz. [Zn(atrz)X]{sub {infinity}} (1.X; X=Cl{sup -}, Br{sup -}, I{sup -}; atrz=3-amino-1,2,4-triazole anion), [Zn{sub 4}(atrz){sub 4}(SCN){sub 4}.H{sub 2}O]{sub {infinity}} (1.SCN.H{sub 2}O) and [Zn(trz)X]{sub {infinity}} (2.X; X=Cl{sup -}, Br{sup -}, I{sup -}; trz=1,2,4-triazole anion), have been hydrothermally synthesized and structurally characterized. Compounds 1.X and 1.SCN.H{sub 2}O are constructed from binuclear planar Zn{sub 2}(atrz){sub 2} subunits and exhibit (4,4) topological network when the subunits are simplified as four-connected nodes. Based on changing the terminal counteranions X (X=Cl{sup -}, Br{sup -}, I{sup -}, SCN{sup -}), the average interlayer separations of 1.X and 1.SCN.H{sub 2}O are enlarged, which equal to 5.851, 6.153, 6.651 and 8.292 A, respectively. As a result, H{sub 2}O molecules reside in the spaces between two adjacent layers of 1.SCN.H{sub 2}O. 2 and 1 are the isomorphous structures. In common with 1, the interlayer separations of 2.X are widened with increasing the ion radius. Solid-state luminescence properties and thermogravimetric analyses of 1 and 2 were investigated, respectively. - Graphical Abstract: Based on employing the various terminal counteranions X (X=Cl{sup -}, Br{sup -}, I{sup -}, SCN{sup -}) the average interlayer separations of four 2D isoreticular layer compounds [Zn(atrz)X]{sub {infinity}} are gradually enlarged, which equal to 5.851, 6.153, 6.651 and 8.292 A, respectively. As a result, guest H{sub 2}O molecules reside in the space between two adjacent layers of [Zn{sub 4}(atrz){sub 4}(SCN){sub 4}.H{sub 2}O]{sub {infinity}}.

  15. Low-energy dissociative electron attachment to CH2Br2, CHClBr2, and CCl3Br: Intermediate lifetimes and decay energetics

    NASA Astrophysics Data System (ADS)

    Parthasarathy, R.; Finch, C. D.; Wolfgang, J.; Nordlander, P.; Dunning, F. B.

    1998-11-01

    Dissociative electron attachment to the brominated methanes CH2Br2, CHClBr2, and CCl3Br is investigated by measuring the velocity and angular distributions of negative ions produced through electron transfer in collisions with velocity selected K(np) Rydberg atoms. The data are analyzed with the aid of a Monte Carlo collision code that models the detailed kinematics of the reactions. Measurements with CH2Br2 show that essentially all the excess energy of reaction appears in translation, indicating that the electron is captured directly into an antibonding orbital. Data for CHClBr2 show that reaction proceeds by two channels: in the first, essentially all the excess energy appears in translation; in the second, limited conversion of the excess energy to internal motions occurs, pointing to a CHClBr2-* intermediate lifetime of ˜0.1 to 1 ps. In the case of CCl3Br, electron transfer leads to the formation of both Br- and Cl- ions. Br- production is again associated with two channels: in one, essentially all the excess energy appears in translation; in the other, near statistical redistribution of the excess energy occurs prior to dissociation, pointing to a relatively long-lived (τ˜several ps) CCl3Br-* intermediate. Data for Cl- production suggest only limited energy transfer to internal motions. Possible reaction mechanisms for the various channels are discussed with the aid of ab initio calculations.

  16. New Scintillator Materials (K2CeBr5) and (Cs2CeBr5)

    NASA Technical Reports Server (NTRS)

    Hawrami, R.; Volz, M. P.; Batra, A. K.; Aggarwal, M. D.; Roy, U. N.; Groza, M.; Burger, A.; Cherepy, Nerine; Niedermayr, Thomas; Payne, Stephen A.

    2008-01-01

    Cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5) are new scintillator materials for X-ray and gamma ray detector applications. Recently halide scintillator materials, such as Ce doped lanthanum bromide has been proved to be very important material for the same purpose. These materials are highly hygroscopic; a search for high light yield non-hygroscopic materials was highly desirable to advance the scintillator technology. In this paper, we are reporting the crystal growth of novel scintillator materials, cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5). Crystals were successfully grown from the melt using the vertical Bridgman-Stockbarger technique, in a comparison with the high performance LaBr3 or LaCl3 crystals, cerium based alkali halides crystals, (Cs2CeBr5) and (K2CeBr5) have similar scintillation properties, while being much less hygroscopic. Furthermore, cesium based compounds will not suffer from the self-activity present in potassium and lanthanum compounds. However the Cs2CeBr5 crystals did not grow properly probably due to non-congruent melting or to some phase transition during cooling. Keywords." Scintillator materials; Ce3+; Energy resolution; Light yield; K2CeBr5

  17. Mechanisms of Tenebrescence and Persistent Luminescence in Synthetic Hackmanite Na8Al6Si6O24(Cl,S)2.

    PubMed

    Norrbo, Isabella; Gluchowski, Pawel; Hyppänen, Iko; Laihinen, Tero; Laukkanen, Pekka; Mäkelä, Jaakko; Mamedov, Fikret; Santos, Hellen S; Sinkkonen, Jari; Tuomisto, Minnea; Viinikanoja, Antti; Lastusaari, Mika

    2016-05-11

    Synthetic hackmanites, Na8Al6Si6O24(Cl,S)2, showing efficient purple tenebrescence and blue/white persistent luminescence were studied using different spectroscopic techniques to obtain a quantified view on the storage and release of optical energy in these materials. The persistent luminescence emitter was identified as impurity Ti(3+) originating from the precursor materials used in the synthesis, and the energy storage for persistent luminescence was postulated to take place in oxygen vacancies within the aluminosilicate framework. Tenebrescence, on the other hand, was observed to function within the Na4(Cl,S) entities located in the cavities of the aluminosilicate framework. The mechanism of persistent luminescence and tenebrescence in hackmanite is presented for the first time.

  18. Magnetic properties of Mn1-xAl1-yNi alloys in the B2 (CsCl-type) structure

    NASA Astrophysics Data System (ADS)

    Paduani, C.; Schaf, J.; Ardisson, J. D.; Takeuchi, A. Y.

    2010-02-01

    In this work is investigated structural and magnetic properties of ferromagnetic Mn1-xAl1-yNi alloys in the κ phase which has a B2 (CsCl-type) structure. The Curie temperatures are above room temperature and decrease with the substitution of Ni for Mn. The magnetic measurements indicate the existence of ferrimagnetism originated from Mn atoms which carry unequal and opposite magnetic moments in different sublattices. A larger average magnetic moment is observed in the Ni-doped system, as compared to the Fe-system, which is due to the formation of larger moment on Mn atoms at the cube corners.

  19. Corrosion behavior of as-cast Mg-8Li-3Al+ xCe alloy in 3.5wt% NaCl solution

    NASA Astrophysics Data System (ADS)

    Manivannan, S.; Dinesh, P.; Mahemaa, R.; MariyaPillai, Nandhakumaran; Kumaresh Babu, S. P.; Sundarrajan, Srinivasan

    2016-10-01

    Mg-8Li-3Al+ xCe alloys ( x = 0.5wt%, 1.0wt%, and 1.5wt%) were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion behavior of the as-cast Mg-8Li-3Al+ xCe alloys were studied under salt spray tests in 3.5wt% NaCl solution at 35°C, in accordance with standard ASTM B-117, in conjunction with potentiodynamic polarization (PDP) tests. The results show that the addition of Ce to Mg-8Li-3Al (LA83) alloy results in the formation of Al2Ce intermetallic phase, refines both the α-Mg phase and the Mg17Al12 intermetallic phase, and then increases the microhardness of the alloys. The results of PDP and salt spray tests reveal that an increase in Ce content to 1.5wt% decreases the corrosion rate. The best corrosion resistance is observed for the LA83 alloy sample with 1.0wt% Ce.

  20. High-resolution proton magnetic resonance and catalytic studies concerning brønsted centers of amorphous Al 2O 3-SiO 2 solids

    NASA Astrophysics Data System (ADS)

    Hunger, M.; Freude, D.; Pfeifer, H.; Bremer, H.; Jank, M.; Wendlandt, K. P.

    1983-08-01

    By application of the magic angle spinning (MAS) technique it was possible to observe highly resolved proton NMR spectra of the OH groups of amorphous silica-alumina. The spectra exhibit two lines at 2 and 7 ppm. The former line must be ascribed to non-acidic OH groups since it also occurs for silica and alumina. The latter line shows a maximum of intensity in the range of 20-30 wt% Al 2O 3. It must be due to acidic hydroxyl groups since the catalytic activity of the silica-aluminas measured by the cracking rate of cumene shows quantitatively the same behaviour with respect to the number of OH groups at 7 ppm.

  1. Normal coordinate analysis and DFT calculations of the vibrational spectra for lanthanide(III) complexes with 3-bromo-4-methoxy-2,6-lutidine N-oxide: LnCl 3(3Br4CH 3OC 7H 7NO) 3 (Ln=Pr, Nd, Sm, Eu, Gd, Dy)

    NASA Astrophysics Data System (ADS)

    Godlewska, P.; Ban-Oganowska, H.; Macalik, L.; Hanuza, J.; Oganowski, W.; Roszak, S.; Lipkowski, P.

    2006-01-01

    The results of the FT-Raman and FT-IR studies of the LnCl 3(LNO) 3 type complexes (where Ln=Pr, Nd, Sm, Eu, Gd, Dy and LNO=3-Br-4-CH 3OC 7H 7NO) are presented. The spectral contours observed in the regions of the lanthanide-oxygen, lanthanide-chlorine and nitrogen-oxygen vibrations are employed in the discussion of the molecular structure of the complex ions and the local symmetry of the LnCl 3(ON) 3 polyhedron. The discussion of the vibrational spectra is based on the classical normal coordinate analysis and its results are compared to the results of DFT quantum chemical calculations performed for complete molecule. The normal coordinate analysis has been performed for PrCl 3(ON) 3 and DyCl 3(ON) 3 molecular systems, which have been treated as a different 'isotopic units'. Basing on the predominant PED contributions of the respective internal coordinates the assignment of the normal vibrations has been proposed.

  2. Line shapes and widths of MAS sidebands for 27Al satellite transitions. multinuclear MAS NMR of tugtupite Na8Al2Be2Si8O24Cl2.

    PubMed

    Skibsted, J; Norby, P; Bildsøe, H; Jakobsen, H J

    1995-12-01

    A multinuclear 9Be, 23Na, 27Al, and 29Si magic-angle spinning (MAS) NMR study has been performed for the mineral tugtupite (Na8Al2Be2Si8O24Cl2). The extremely well-resolved spectra allow observation of separate spinning sidebands (ssb's) from the inner (+/- 1/2, +/- 3/2) and outer (+/- 3/2, +/- 5/2) 27Al satellite transitions, and are utilized in a detailed analysis of the line shapes and widths of the individual ssb's from simulations. The line widths of the ssb's from the inner and outer 27Al satellite transitions are found to decrease systematically with increasing order of the ssb's across the spectrum. Accurate values for the 9Be, 23Na, and 27Al quadrupole coupling parameters and isotropic chemical shifts are obtained from simulations of the manifolds of ssb's from the satellite transitions. MAS NMR of the 9Be satellite transitions for tugtupite, BeO, and beryl(Al2Be3Si6O18) shows that these transitions are particularly useful for determination of 9Be quadrupole couplings because of the small 9Be quadrupole moment. The 29Si shielding anisotropy of delta sigma = 48 ppm in tugtupite is the largest determined so far for a framework SiO4 tetrahedron. Finally, the crystal structure of the tugtupite sample has been refined by single-crystal X-ray diffraction, and correlations between the multinuclear NMR parameters and structural data are reported.

  3. X-ray and neutron diffraction studies of the polyhydrido complex FeH6Mg4Br/sub 3. 5/Cl/sub 0. 5/(C4H8O)9: discussion of binary transition-metal hydride anions of the type (MH/sub x/)/sup n-/

    SciTech Connect

    Bau, R.; Chiang, M.Y.; Ho, D.M.; Gibbins, S.G..; Emge, T.J.; Koetzle, T.F.

    1984-01-01

    The molecular structure of the polyhydrido complex FeH6Mg4X4(THF)8 (X4 = Br/sub 3.5/Cl/sub 0.5/) has been determined by single-crystal X-ray and neutron diffraction methods. The X-ray structure determination was carried out at room temperature, revealing an octahedral (FeH6)U core with (MgBr(THF)2) units situated over four of the eight faces of the octahedron. The (FeH6)U core exhibits crystallographic twofold symmetry, with an average Fe-H distance (as determined in the X-ray study) of 1.69 (9) A. Neutron diffraction analysis of the title compound (carried out at 80 K at the Brookhaven High-Flux Beam Reactor on a crystal of volume 12 mmT) fully confirmed this basic molecular geometry, yielding much more precise H positions. The Fe-H (1.609 (2) A) and Mg-H (2.045 (18) A) distances obtained from the neutron study support the idea that the Fe-H bond is largely covalent in nature while the Mg-H interaction is largely ionic. A detailed discussion of available structural information for binary transition-metal hydride anions, (MH/sub x/)/sub n-/, is given in the text. Crystallographic details for the X-ray analysis of the title compound C32H70Br/sub 3.5/Cl/sub 0.5/FeMg4O8 is included. Details for the neutron analysis at 80 Z are also reported. 52 references, 2 figures, 4 tables.

  4. SEM, EDX and vibrational spectroscopic study of the mineral tunisite NaCa2Al4(CO3)4Cl(OH)8.

    PubMed

    Frost, Ray L; López, Andrés; Scholz, Ricardo; de Oliveira, Fernando A N

    2015-02-05

    The mineral tunisite has been studied by using a combination of scanning electron microscopy with energy dispersive X-ray fluorescence and vibrational spectroscopy. Chemical analysis shows the presence of Na, Ca, Al and Cl. SEM shows a pure single phase. An intense Raman band at 1127 cm(-1) is assigned to the carbonate ν1 symmetric stretching vibration and the Raman band at 1522 cm(-1) is assigned to the ν3 carbonate antisymmetric stretching vibration. Infrared bands are observed in similar positions. Multiple carbonate bending modes are found. Raman bands attributable to AlO stretching and bending vibrations are observed. Two Raman bands at 3419 and 3482 cm(-1) are assigned to the OH stretching vibrations of the OH units. Vibrational spectroscopy enables aspects of the molecular structure of the carbonate mineral tunisite to be assessed.

  5. Moderate temperature sodium cells. V - Discharge reactions and rechargeability of NiS and NiS2 positive electrodes in molten NaAlCl4

    NASA Technical Reports Server (NTRS)

    Abraham, K. M.; Elliot, J. E.

    1984-01-01

    NiS2 and NiS have been characterized as high energy density rechargeable positive electrodes for moderate-temperature Na batteries of the configuration, Na(1)/beta double prime-Al2O3/NaAlCl4(1), NiSx. The batteries operate in the temperature range 170 - 190 C. Positive electrode reactions during discharge/charge cycles have been characterized. Excellent rechargeability of the batteries has been demonstrated by extended cell cycling. A Na/NiS2 cell, operating at 190 C, exceeded 600 deep discharge/charge cycles with practically no capacity deterioration. The feasibility of secondary Na/NiSx batteries with specific energies equal to or greater than 50 Wh/lb and cycle lifes exceeding 1000 deep discharge/charge cycles has been demonstrated.

  6. Molecular modeling of the structure and dynamics of the interlayer species of ZnAlCl layered double hydroxide.

    PubMed

    Pisson, J; Morel, J P; Morel-Desrosiers, N; Taviot-Guého, C; Malfreyt, P

    2008-07-03

    Molecular dynamics simulations of the ZnAl layered double hydroxide containing interlayer chloride anions have been performed in the NpT and Np(zz)T statistical ensembles for metal Zn/Al ratios of 2 and 3. We have monitored the interlayer spacing as a function of the number of intercalated water molecules for each statistical ensemble. We have studied how these profiles are affected by the method of calculation of the charges of the hydroxide layer atoms. Diffusion coefficients of the interlayer water molecules have been calculated for different Zn/Al ratios. The calculation of the chemical potential of the interlayer water molecules has been carried out for three amounts of interlayer water molecules. The calculation showed a qualitative agreement with the bulk water chemical potential within a range of interlayer water molecule contents.

  7. Phase relationships in positive electrodes of high temperature Li-Al/LiCl-KCl/FeS2 cells

    NASA Astrophysics Data System (ADS)

    Tomczuk, Z.; Tani, B.; Otto, N. C.; Roche, M. F.; Vissers, D. R.

    1982-05-01

    The phases present in FeS2 electrodes operated in LiCl-KCl eutectic electrolyte are determined by X-ray diffraction and metallographic examination. The phases are FeS2, KFeS2, Li3Fe2S4, Li2.33Fe0.67S2, Fe/1-x/S, Li2FeS2, LiK6Fe24S26Cl, Li2S, and Fe. The metallographic and crystallographic characteristics of these phases are given. The sequence of Li-Fe-S phases in the FeS2 electrode is found to be in accord with the sequence predicted from the equilibrium LiFe-S phase diagram. It is noted that two of the Li-Fe-S phases found at room temperature (Li2.33Fe0.67S2 and Li2FeS2) result from decomposition on cooling of a solid solution phase: Li/2+x/Fe/1-x/S2, x ranging from 0 to 0.33.

  8. Tribocorrosion Behavior of Fe-Based Amorphous Composite Coating Reinforced by Al2O3 in 3.5% NaCl Solution

    NASA Astrophysics Data System (ADS)

    Yasir, Muhammad; Zhang, Cheng; Wang, Wei; Zhang, Zhi-Wei; Liu, Lin

    2016-12-01

    Although corrosion and friction/wear behavior of Fe-based amorphous coatings and their composites has been extensively studied during the past decade, there is very limited work related to tribocorrosion behavior. In this paper, the tribocorrosion behavior of a Fe-based amorphous composite coating reinforced with 20 wt.% Al2O3 particles was investigated in a 3.5% NaCl solution on a ball-on-disk tester and was compared to the monolithic amorphous coating and 316L stainless steel (SS). The results showed that the amorphous composite coating exhibited the highest tribocorrosion resistance among the three materials tested, as evidenced by the lowest coefficient of friction ( 0.3) and tribocorrosion wear rate ( 1.2 × 10-5 mm3/N·m). In addition, potentiodynamic polarization measurements before and during tribocorrosion testing demonstrated that corrosion resistance of the amorphous composite coating was not influenced so much by mechanical loading compared to the amorphous coating and the 316L SS. Observations on the worn surface revealed a corrosion-wear- and oxidational-wear-dominated tribocorrosion mechanism for the composite coatings. The excellent tribocorrosion resistance of the composite coating results from the effect of chemically stable Al2O3 phase which resists oxidation and delamination during sliding, along with poor wettability with corrosive NaCl droplets.

  9. The BR eigenvalue algorithm

    SciTech Connect

    Geist, G.A.; Howell, G.W.; Watkins, D.S.

    1997-11-01

    The BR algorithm, a new method for calculating the eigenvalues of an upper Hessenberg matrix, is introduced. It is a bulge-chasing algorithm like the QR algorithm, but, unlike the QR algorithm, it is well adapted to computing the eigenvalues of the narrowband, nearly tridiagonal matrices generated by the look-ahead Lanczos process. This paper describes the BR algorithm and gives numerical evidence that it works well in conjunction with the Lanczos process. On the biggest problems run so far, the BR algorithm beats the QR algorithm by a factor of 30--60 in computing time and a factor of over 100 in matrix storage space.

  10. M{sub 1-x}[W{sub 2}O{sub 2}X{sub 6}] with M=K{sup +}, Tl{sup +}, Ag{sup +}, Hg{sup 2+}, Pb{sup 2+}; X=Cl, Br-A class of mixed valence tungsten (IV,V) compounds with layered structures, W-W bonds and high conductivity

    SciTech Connect

    Beck, Johannes . E-mail: j.beck@uni-bonn.de; Kusterer, Christian; Hoffmann, Rolf-Dieter; Poettgen, Rainer

    2006-08-15

    The crystal structure of WOCl{sub 3}, determined on the basis of powder diffraction data (tetragonal, P4{sub 2}/mnm, a=10.6856(6), c=3.8537(2)), is isotypic to WOI{sub 3} and contains one-dimensional strands of edge-sharing double-octahedral W{sub 2}O{sub 4/2}Cl{sub 6} groups connected via common corners in trans position. A W-W bond of 2.99A is present within the planar W{sub 2}Cl{sub 6} groups. A series of non-stochiometric, mixed valence W(IV,V) compounds M{sub 1-x}[W{sub 2}O{sub 2}Cl{sub 6}] can be obtained from WOCl{sub 3} by reaction with metal halides (TlCl, KCl, PbCl{sub 2}) or by reaction of elemental Hg with WOCl{sub 4}. All were characterized by single crystal structure determinations and EDX measurements (Tl{sub 0.981(2)}[W{sub 2}O{sub 2}Cl{sub 6}]: monoclinic, C2/m, a=12.7050(4), b=3.7797(1), c=10.5651(3)A, {beta}=107.656(1){sup o}; K{sub 0.84(2)}[W{sub 2}O{sub 2}Cl{sub 6}]: monoclinic, C2/m, a=12.812(3), b=3.7779(6), c=10.196(3)A, {beta}=107.422(8){sup o}; Pb{sub 0.549(3)}[W{sub 2}O{sub 2}Cl{sub 6}]: orthorhombic, Immm,a=3.7659(1), b=9.8975(4), c=12.1332(6)A; Hg{sub 0.554(6)}[W{sub 2}O{sub 2}Cl{sub 6}]: monoclinic, C2/m, a=12.8361(8), b=3.7622(3), c=10.2581(9)A, {beta}=113.645(3){sup o}). Two representatives of this family of compounds have already been reported: Na[W{sub 2}O{sub 2}Br{sub 6}] [Y.-Q. Zhang, K. Peters, H.G. von Schnering, Z. Anorg. Allg. Chem. 624 (1998) 1415-1418] and Ag{sub 0.74}[W{sub 2}O{sub 2}Br{sub 6}] [S. Imhaine, C. Perrin, M. Sergent, Mat. Res. Bull. 33 (1998) 927-933]. The Ag containing compound can be obtained from elemental Ag and WOBr{sub 3}. The crystal structure, originally reported in the triclinic system, was redetermined and shown to be monoclinic with space group C2/m (a=13.7338(10), b=3.7769(3), c=10.7954(9)A, {beta}=112.401(3){sup o}). The crystal structures of these compounds are in close relationship to the structure of WOCl{sub 3} and all contain W{sub 2}O{sub 4/2}X{sub 6} (X=Cl, Br) double strands with the mono

  11. Hydrogen for X-group exchange in CH3X, X = Cl, Br, I, OMe and NMe2 byMonomeric [1,2,4-(Me3C)3C5H2]2CeH: Experimental and Computational Support for a Carbenoid Mechanism

    SciTech Connect

    Werkema, Evan; Andersen, Richard; Yahia, Ahmed; Maron, Laurent; Eisenstein, Odile

    2009-05-15

    The reaction between [1,2,4-(Me3C)3C5H2]2CeH, referred to as Cp'2CeH, andCH3X where X is Cl, Br, I, OMe and NMe2, are described. The reactions fall intothree distinct classes. Class a, where X = Cl, Br and I rapidly form Cp'2CeX and CH4without formation of identifiable intermediates in the 1H NMR spectra. Class b, whereX = OMe proceeds rapidly to Cp'2Ce(eta2-CH2OMe) and H2 and then to Cp'2CeOMeand CH4. The methoxymethyl derivative is sufficiently stable to be isolated andcharacterized and it is rapidly converted to Cp'2CeOMe in presence of BPh3. Class c,where X = NMe2 does not result in formation of Cp'2CeNMe2, but deuterium labelingexperiments show that H for D exchange occurs in NMe3. Density functionalcalculations DFT(B3PW91) on the reaction of (C5H5)2CeH, referred to as Cp2CeH,and CH3X show that the barrier for alpha-CH activation, resulting in formation ofCp2Ce(eta2-CH2X), proceeds with a relatively low activation barrier (DeltaG++) but thesubsequent ejection of CH2 and trapping by H2 has a higher barrier; the height of thesecond barrier lies in the order F, Cl, Br, I< OMe<< NMe2, consistent with theexperimental studies. The DFT calculations also show that the two-step reaction,which proceeds through a carbenoid intermediate, has a lower barrier than a directone-step sigma bond metathesis mechanism. The reaction of Cp2CeCH2OMe and BPh3 is calculated to be a low barrier process and the ylide, CH2(+)BPh3(-), is a transition state and not an intermediate.

  12. The co-crystallization of beryl-structure compounds in the Al 2Be 3Si 6O 18—Mg,Ca/F,Cl system

    NASA Astrophysics Data System (ADS)

    Mikhailov, M. A.

    2005-02-01

    An Al 2Be 3Si 6O 18 — Mg, Ca/F, Cl flux system unused earlier has been chosen for the synthesis of beryl (Al 2Be 3Si 6O 18) and its varieties. In such a case of disregarding the well-known rules of the choice of a solvent, the following crystallization features of beryl have been revealed: (1) the beryl co-crystallizes successively and/or simultaneously with isostructural beryllian indialite (Mg 2BeAl 2Si 6O 18); (2) the bulk of beryl crystals is formed only in regions with high concentration of a flux; (3) the solution-melt liquates; (4) the solvent evaporates intensively. The advantages of the flux proposed are both the possibility of using inexpensive steel crucibles and good chromophoric properties of Cr, V, and Ti. Ratios of constitutient elements and some additive those between beryl and beryllian indialite, both grown simultaneously, and between pinacoid and prism in crystals of these compounds are reported.

  13. Theoretical study of Pt(PR3)(2)(AlCl3) (R = H, Me, Ph, or Cy) including an unsupported bond between transition metal and non-transition metal elements: geometry, bond strength, and prediction.

    PubMed

    Tsukamoto, Shinya; Sakaki, Shigeyoshi

    2011-08-04

    The molecular structure and the binding energy of Pt(PR(3))(2)(AlCl(3)) (R = H, Me, Ph, or Cy) were investigated by DFT, MP2 to MP4(SDTQ), and CCSD(T) methods. The optimized structure of Pt(PCy(3))(2)(AlCl(3)) (Cy = cyclohexyl) by the DFT method with M06-2X and LC-BLYP functionals agrees well with the experimental one. The MP4(SDTQ) and CCSD(T) methods present similar binding energies (BE) of Pt(PH(3))(2)(AlCl(3)), indicating that these methods provide reliable BE value. The DFT(M06-2X)-calculated BE value is close to the MP4(SDTQ) and CCSD(T)-calculated values, while the other functionals present BE values considerably different from the MP4(SDTQ) and CCSD(T)-calculated values. All computational methods employed here indicate that the BE values of Pt(PMe(3))(2)(AlCl(3)) and Pt(PPh(3))(2)(AlCl(3)) are considerably larger than those of the ethylene analogues. The coordinate bond of AlCl(3) with Pt(PR(3))(2) is characterized to be the σ charge transfer (CT) from Pt to AlCl(3). This complex has a T-shaped structure unlike the well-known Y-shaped structure of Pt(PMe(3))(2)(C(2)H(4)), although both are three-coordinate Pt(0) complex. This T-shaped structure results from important participation of the Pt d(σ) orbital in the σ-CT; because the Pt d(σ) orbital energy becomes lower as the P-Pt-P angle decreases, the T-shaped structure is more favorable for the σ-CT than is the Y-shaped structure. [Co(alcn)(2)(AlCl(3))](-) (alcn = acetylacetoneiminate) is theoretically predicted here as a good candidate for the metal complex, which has an unsupported M-Al bond because its binding energy is calculated to be much larger than that of Pt(PCy(3))(2)(AlCl(3)).

  14. Identification and quantification of Sn-based species in trimetallic Pt-Sn-In/Al2O3-Cl naphtha-reforming catalysts

    NASA Astrophysics Data System (ADS)

    Jumas, Jean-Claude; Sougrati, Moulay Tahar; Olivier-Fourcade, Josette; Jahel, Ali; Avenier, Priscilla; Lacombe, Sylvie

    2013-04-01

    Trimetallic Pt/Al2O3SnIn-Cl naphtha-reforming catalysts were prepared via co-precipitation route. Platinum and chlorine were introduced by the incipient wetness technique on the alumina support already doped with about 0.3 %wt of Sn to obtain about 0.3 %wt of Pt and 1.5 %wt of Cl. For the same Pt, Sn and Cl composition, indium loading ranged from 0.06 to 0.6 wt.%. The obtained catalysts were investigated by 119Sn Mössbauer spectroscopy between 95 and 300 K. Two Sn(IV), Sn(II) and Sn(0) environments have been identified and well characterized by their hyperfine parameters. The Lamb-Mössbauer factors have been determined for each environment and found to be 0.53, 0.27 and 0.31 for Sn(IV), Sn(II) and Sn(0) respectively. The addition of indium has been found to favour the formation of PtxSn alloys. 119Sn Mössbauer spectroscopy results show that addition of even small amount of In (0.06 wt.%) leads to the formation of a Pt3Sn alloy. At higher indium loadings, higher amounts of PtxSn alloys of almost equal Pt and Sn atomic concentrations were detected. The increasing formation of PtxSn alloys with higher indium loading is in good correlation with a decrease of catalyst's overall conversion and selectivity to C1 and C3-C4 paraffins and increase of isomerization selectivity.

  15. A comparative study of the redox and excited state properties of (nBu4N)2[Mo6X14] and (nBu4N)2[Mo6X8(CF3COO)6] (X = Cl, Br, or I).

    PubMed

    Kirakci, Kaplan; Kubát, Pavel; Langmaier, Jan; Polívka, Tomáš; Fuciman, Marcel; Fejfarová, Karla; Lang, Kamil

    2013-05-21

    The excited-state dynamics, luminescence, and redox properties of a series of hexanuclear molybdenum cluster complexes, (nBu4N)2[Mo6X14] and (nBu4N)2[Mo6X8(CF3COO)6] (X = Cl, Br, or I), were investigated. Substitution of the apical halogen ligands for the trifluoroacetate ligands increased the oxidation potentials and induced a blue shift in the absorption and luminescence bands as well as a considerable increase in the luminescence quantum yields for heavy inner ligands. Time-resolved transient absorption measurements showed that the intersystem crossing from the excited singlet states is ultrafast with time constants ranging between <120 fs and 1.68 ps and leads to hot triplet states. The following cooling occurred at a ps time scale and was assigned to electronic redistribution within the emissive triplet state sublevels. The formation of singlet oxygen, O2((1)Δg), suggested earlier on the basis of photooxidation experiments for some complexes, was revised by direct measurements of O2((1)Δg) phosphorescence. We showed the effects of the attached ligands on key physico-chemical and photophysical parameters of the title complexes. The synthesis and structural characterisation of a new cluster complex, (nBu4N)2[Mo6Br8(CF3COO)6], completed the series. Our results demonstrated that the complexes with heavy inner ligands (Br, I) and apical trifluoroacetate ligands were photochemically and electrochemically stable, highly luminescent, and good sensitisers of O2((1)Δg).

  16. Thermal Variance Investigation and Scintillation Mechanisms of Cs2LiLaBr6-xClx:Ce (CLLBC) and Cs2LiYBr6:Ce (CLYB)

    SciTech Connect

    Coupland, Daniel David Schechtman; Budden, Brent Scott; Stonehill, Laura Catherine

    2015-11-23

    We perform an investigation into the scintillation processes and performance of elpasolites Cs2LiLaBr6-xClx:Ce (CLLBC) and Cs2LiYBr6:Ce (CLYB) using a thermal cycle over a range of -20 to +50º C. At 10º increments, we acquire data with both a waveform digitizer and charge-integrating electronics. We identify decay components and evaluate decay times, thermal neutron gamma-equivalent energy (GEE), and pulse shape discrimination (PSD) performance. Results are compared to common Cs2LiYCl6:Ce (CLYC).

  17. Measuring spectral transmission and refractive index of AgCl1-xBrx (0 ⩽ x ⩽ 1) and Ag1-xTlxBr1-xIx (0 ⩽ x ⩽ 0.05) at the wavelength of 10.6 μm

    NASA Astrophysics Data System (ADS)

    Korsakov, Alexandr S.; Vrublevsky, Dmitry S.; Zhukova, Liya V.

    2015-12-01

    We measured the complex refractive index at the wavelength of 10.6 μm with the help of Fourier transform infrared spectroscopy for polycrystalline plates of the following compositions AgCl1-xBrx (0 ⩽ x ⩽ 1) and Ag1-xTlxBr1-xIx, where x varied from 0 to 0.05. In order to do it we chose a segment of the spectrum, which was recorded with a high resolution (0.5 cm-1) using the HgCdTe detector and which had a set of 10 identical peaks. It is shown that the real part of the refractive index rises along with increasing the substituting component fraction in the solid solution from 1.99 to 2.17 for AgCl1-xBrx and from 2.17 to 2.24 within the range of TlI mole fraction up to 0.05 for Ag1-xTlxBr1-xIx. We considered errors introduced by the spectrometer resolution and the accuracy rating of the micrometer, which was used to measure sample thickness. It is seen in the spectra, recorded for the second system with a lower resolution and using a deuterated and L-alanine doped triglycine sulfate detector, that increasing the thallium monoiodide fraction results in widening the transmission range towards bigger wavelengths. We also plan to use the obtained refractive index values for simulating mid-infrared optical fibers, the polycrystalline structure of which is close to the structure of the plates under investigation.

  18. Bee Line BR-1 Racer

    NASA Technical Reports Server (NTRS)

    1926-01-01

    Bee Line BR-1 Racer: The Bee Line BR-1 was a racing aircraft used to compete in the 1922 Pulitzer Air Race. The aircraft and its sister ship, the Bee Line BR-2, came to Langley and the NACA in 1926. The BR-1 is shown in the NACA hangar at Langley Field in early 1926.

  19. Flexible All-Inorganic Perovskite CsPbBr3 Nonvolatile Memory Device.

    PubMed

    Liu, Dongjue; Lin, Qiqi; Zang, Zhigang; Wang, Ming; Wangyang, Peihua; Tang, Xiaosheng; Zhou, Miao; Hu, Wei

    2017-02-22

    All-inorganic perovskite CsPbX3 (X = Cl, Br, or I) is widely used in a variety of photoelectric devices such as solar cells, light-emitting diodes, lasers, and photodetectors. However, studies to understand the flexible CsPbX3 electrical application are relatively scarce, mainly due to the limitations of the low-temperature fabricating process. In this study, all-inorganic perovskite CsPbBr3 films were successfully fabricated at 75 °C through a two-step method. The highly crystallized films were first employed as a resistive switching layer in the Al/CsPbBr3/PEDOT:PSS/ITO/PET structure for flexible nonvolatile memory application. The resistive switching operations and endurance performance demonstrated the as-prepared flexible resistive random access memory devices possess reproducible and reliable memory characteristics. Electrical reliability and mechanical stability of the nonvolatile device were further tested by the robust current-voltage curves under different bending angles and consecutive flexing cycles. Moreover, a model of the formation and rupture of filaments through the CsPbBr3 layer was proposed to explain the resistive switching effect. It is believed that this study will offer a new setting to understand and design all-inorganic perovskite materials for future stable flexible electronic devices.

  20. The importance of dye chemistry and TiCl4 surface treatment in the behavior of Al2O3 recombination barrier layers deposited by atomic layer deposition in solid-state dye-sensitized solar cells.

    PubMed

    Brennan, Thomas P; Bakke, Jonathan R; Ding, I-Kang; Hardin, Brian E; Nguyen, William H; Mondal, Rajib; Bailie, Colin D; Margulis, George Y; Hoke, Eric T; Sellinger, Alan; McGehee, Michael D; Bent, Stacey F

    2012-09-21

    Atomic layer deposition (ALD) was used to fabricate Al(2)O(3) recombination barriers in solid-state dye-sensitized solar cells (ss-DSSCs) employing an organic hole transport material (HTM) for the first time. Al(2)O(3) recombination barriers of varying thickness were incorporated into efficient ss-DSSCs utilizing the Z907 dye adsorbed onto a 2 μm-thick nanoporous TiO(2) active layer and the HTM spiro-OMeTAD. The impact of Al(2)O(3) barriers was also studied in devices employing different dyes, with increased active layer thicknesses, and with substrates that did not undergo the TiCl(4) surface treatment. In all instances, electron lifetimes (as determined by transient photovoltage measurements) increased and dark current was suppressed after Al(2)O(3) deposition. However, only when the TiCl(4) treatment was eliminated did device efficiency increase; in all other instances efficiency decreased due to a drop in short-circuit current. These results are attributed in the former case to the similar effects of Al(2)O(3) ALD and the TiCl(4) surface treatment whereas the insulating properties of Al(2)O(3) hinder charge injection and lead to current loss in TiCl(4)-treated devices. The impact of Al(2)O(3) barrier layers was unaffected by doubling the active layer thickness or using an alternative ruthenium dye, but a metal-free donor-π-acceptor dye exhibited a much smaller decrease in current due to its higher excited state energy. We develop a model employing prior research on Al(2)O(3) growth and dye kinetics that successfully predicts the reduction in device current as a function of ALD cycles and is extendable to different dye-barrier systems.

  1. Memory Enhancement of Acteoside (Verbascoside) in a Senescent Mice Model Induced by a Combination of D-gal and AlCl3.

    PubMed

    Gao, Li; Peng, Xiao-Ming; Huo, Shi-Xia; Liu, Xin-Ming; Yan, Ming

    2015-08-01

    Acteoside, also known as verbascoside or orobanchin, is a common compound found in many important medicinal plants including the Chinese herb Cistanche deserticola Y. C. Ma, which is used for its neuroprotective and memory enhancement properties. We have investigated the effects of acteoside using a senescent mouse model induced by a combination of chronic intraperitoneal administration of d-gal (60 mg/kg/day) and oral administration AlCl3 (5 mg/kg/day) once daily for 90 days. After 60 days, acteoside (30, 60, and 120 mg/kg/day) was orally administered once daily for 30 days. The memory enhancing effects of acteoside were evaluated using the Morris water maze test. The results showed that 30-120 mg/kg/day of acteoside reduced the escape latency in finding the platform, and increased the number of crossings of the platform. A 30-120 mg/kg/day of acteoside increased significantly the expression of nerve growth factor and tropomycin receptor kinase A mRNA and protein in the hippocampus, measured using real-time RT-PCR, immunohistochemical analysis, and western blotting. These results support the use of C. deserticola for memory enhancement and indicate that the effects of acteoside are induced via promotion of nerve growth factor and tropomycin receptor kinase A expression.

  2. Removal of arsenic from water by Friedel's salt (FS: 3CaO·Al2O3·CaCl2·10H2O).

    PubMed

    Zhang, Danni; Jia, Yongfeng; Ma, Jiayu; Li, Zhibao

    2011-11-15

    Low levels of arsenic can be effectively removed from water by adsorption onto various materials and searching for low-cost, high-efficiency new adsorbents has been a hot topic in recent years. In the present study, the performance of Friedel's salt (FS: 3CaO·Al(2)O(3)·CaCl(2)·10H(2)O), a layered double hydroxide (LDHs), as an adsorbent for arsenic removal from aqueous solution was investigated. Friedel's salt was synthesized at lower temperature (50°C) compared to traditional autoclave methods by reaction of calcium chloride with sodium aluminate. Kinetic study revealed that adsorption of arsenate by Friedel's salt was fast in the first 12h and equilibrium was achieved within 48 h. The adsorption kinetics are well described by second-order Lageren equation. The adsorption capacity of the synthesized sorbent for arsenate at pH 4 and 7 calculated from Langmuir adsorption isotherms was 11.85 and 7.80 mg/g, respectively. Phosphate and silicate markedly decreased the removal of arsenate, especially at higher pH, but sulfate was found to suppress arsenate adsorption at lower pH and the adverse effect was disappeared at pH ≥ 6. Common metal cations (Ca(2+), Mg(2+)) enhanced arsenate adsorption. The results suggest that Friedel's salt is a potential cost-effective adsorbent for arsenate removal in water treatment.

  3. Synthesis, characterization and sorption properties of functionalized Cr-MIL-101-X (X=–F, –Cl, –Br, –CH{sub 3}, –C{sub 6}H{sub 4}, –F{sub 2}, –(CH{sub 3}){sub 2}) materials

    SciTech Connect

    Buragohain, Amlan; Couck, Sarah; Van Der Voort, Pascal; Denayer, Joeri F.M.; Biswas, Shyam

    2016-06-15

    Four existing and three new functionalized chromium terephthalates having MIL-101 topology and denoted as Cr-MIL-101-X (existing ones with X=–F, 1-F; –Cl, 2-Cl; –Br, 3-Br; –CH{sub 3}, 4-CH{sub 3}; new ones with X=–C{sub 6}H{sub 4}, 5-C{sub 6}H{sub 4}; –F{sub 2}, 6-F{sub 2}, –(CH{sub 3}){sub 2}, 7-(CH{sub 3}){sub 2}) were synthesized under hydrothermal conditions. All the materials except 5-C{sub 6}H{sub 4} could be prepared by a general synthetic route, in which the mixtures of CrO{sub 3}, H{sub 2}BDC-X (BDC=1,4-benzenedicarboxylate) linkers, conc. HCl and water with a molar ratio of 1:1:3.9:222.2 were reacted at 180 °C for 144 h. Compared to the 144 h of synthesis time, three of the compounds, namely 1-Cl, 2-Br and 5-C{sub 6}H{sub 4}, could be prepared in much shorter reaction times (12–18 h at 180–210 °C). The materials possess high thermal stability up to 270–300 °C in an air atmosphere. The activated compounds exhibit significant porosity (S{sub BET} range: 1273–2135 m{sup 2} g{sup −1}). At 0 °C and 1 bar, the CO{sub 2} adsorption capacities of the compounds fall in the 1.7–2.9 mmol g{sup −1} range. Compounds 1-F and 6-F{sub 2} showed enhanced CO{sub 2} uptake values compared to parent Cr-MIL-101. The benzene adsorption capacities of the compounds lie in the range of 66.2–139.5 molecules per unit cell at 50 °C and p/p{sub 0}=0.35. The increased benzene uptake value of 1-F compared to un-functionalized Cr-MIL-101 and 4-CH{sub 3} suggests that the fluorination has induced more hydrophobicity in Cr-MIL-101 as compared to the methylation. - Graphical abstract: Benzene adsorption by seven functionalized Cr-MIL-101-X metal-organic framework (MOF) materials Display Omitted - Highlights: • Seven functionalized Cr-MIL-101-X materials were synthesized solvothermally. • All Cr-MIL-101-X materials exhibited high thermal stability up to 270–300 °C in air. • All Cr-MIL-101-X compounds displayed considerable porosity towards N{sub 2

  4. Selective formation of the [PhP(H)-PPh]- anion in the reaction of PhPHLi with MeAlCl(2); synthesis and structure of the unusual tetramer [(PhP(H)-PPh)Li.thf]4.

    PubMed

    Garcia, Felipe; Humphrey, Simon M; Kowenicki, Richard A; McPartlin, Mary; Wright, Dominic S

    2004-04-07

    The reaction of PhPHLi with MeAlCl(2)(3:1 equivalents) gives the tetramer [(PhP(H)-PPh)Li.thf]4, and provides the first direct evidence of a link between the reactivity patterns observed for Group 14 and 15 phosphanenides and those of Group 13.

  5. Comment to “Chlorine stable isotopes and halogen concentrations in convergent margins with implications for the Cl isotopes cycle in the ocean” by Wei et al. A review of the Cl isotope composition of serpentinites and the global chlorine cycle

    NASA Astrophysics Data System (ADS)

    Sharp, Z. D.; Barnes, J. D.

    2008-10-01

    Wei et al. [Wei, W., Kastner, M., Spivack, A., 2008. Chlorine stable isotope and halogen concentrations in convergent margins with implications for the Cl isotopes cycle in the ocean. Earth Planet. Sci. Lett. 266, 90-104] published chlorine isotope data for pore fluids and serpentinites from three subduction zones and two obducted serpentinites. The measured δ37Cl values of serpentinites ranged from 1.2 to 6.0‰ (vs. SMOC), far higher than all other published data for serpentinites. The explanation for these high δ37Cl values defies known fractionation mechanisms. Instead, the anomalous δ37Cl values are almost certainly due to analytical artifacts known to exist for the method the authors employed. Wei et al. [Wei, W., Kastner, M., Spivack, A., 2008. Chlorine stable isotope and halogen concentrations in convergent margins with implications for the Cl isotopes cycle in the ocean. Earth Planet. Sci. Lett. 266, 90-104] concluded that if high δ37Cl serpentinites (˜ 6‰) were subducted into the mantle, then a change in the δ37Cl value of the crustal reservoir would be observed in the evaporite record over the last 200Ma. Because the Cl isotope composition of the crustal reservoirs has been constant over this time period, as constrained by evaporites, they argue that Cl in serpentinites is recycled back to the oceans. This argument is flawed for two reasons. First, the δ37Cl values of serpentinites is close to 0‰, not 6‰ as suggested in their paper. Second, the δ37Cl value of the crustal reservoir would change immeasurably over 200Ma even if serpentinites of 6‰ were subducted into the mantle. In fact, it has been shown that the crust, mantle and chondritic reservoir all have δ37Cl values close to 0‰ [Sharp, Z.D., Barnes, J.D., Brearley, A.J., Fischer, T.P., Chaussidon, M., Kamenetsky, V.S., 2007. Chlorine isotope homogeneity of the mantle, crust and carbonaceous chondrites. Nature 446, 1062-1065]. No secular variation in the δ37Cl value of the crust

  6. CsEuBr3: Crystal structure and its role in the photostimulation of CsBr :Eu2+

    NASA Astrophysics Data System (ADS)

    Hesse, S.; Zimmermann, J.; von Seggern, H.; Ehrenberg, H.; Fuess, H.; Fasel, C.; Riedel, R.

    2006-10-01

    CsBr :Eu2+ has recently been investigated as a photostimulable x-ray storage phosphor with great potential for application in high-resolution image plates. In a recent paper Hackenschmied et al. [J. Appl. Phys. 93, 5109 (2003)] suggested that segregations of CsEuBr3 or Cs4EuBr6 formed within CsBr :Eu2+ during annealing are responsible for an increase in the photostimulated luminescence (PSL) yield. In this work single crystals of CsEuBr3 were prepared by a one step synthesis and identified by x-ray diffraction (XRD) analysis as single phase perovskites. It was concluded that, after preparation, CsEuBr3 degrades in normal atmosphere into at least two phases, one of which is the orthorhombic structure of Cs2EuBr5•10H2O. The XRD powder diffraction pattern of this compound is very similar to that of the segregations observed within CsBr :Eu2+ and reported by Hackenschmied et al. However, the increased PSL yield in CsBr :Eu2+ after annealing cannot be due to the segregations, because the trivalent nature of the europium in the segregations renders them PSL inactive.

  7. Etude structurale et vibrationnelle d’un nouveau composé complexe de cobalt: [Co(imidazole)4Cl]Cl

    PubMed Central

    Derbel, Amira; Mhiri, Tahar; Graia, Mohsen

    2015-01-01

    In the title complex, chlorido­tetra­kis­(1H-imidazole-κN 3)cobalt(II) chloride, [CoCl(C3H4N2)4]Cl, the CoII cation has a distorted square-pyramidal coordination environment. It is coordinated by four N atoms of four imidazole (Im) groups in the basal plane, and by a Cl atom in the apical position. It is isostructural with [Cu(Im)4Cl]Cl [Morzyk-Ociepa et al. (2012 ▸). J. Mol. Struct. 1028, 49–56] and [Cu(Im)4Br]Br [Hossaini Sadr et al. (2004 ▸). Acta Cryst. E60, m1324–m1326]. In the crystal, the [CoCl(C3H4N2)4]+ cations and Cl− anions are linked via N—H⋯Cl hydrogen bonds, forming layers parallel to (010). These layers are linked via C—H⋯Cl hydrogen bonds and C—H⋯π and π–π [inter-centroid distance = 3.794 (2) Å] inter­actions, forming a three-dimensional framework. The IR spectrum shows vibrational bands typical for imidazol groups. The monoclinic unit cell of the title compound emulates an ortho­rhom­bic cell as its β angle is close to 90°. The crystal is twinned, with the refined ratio of twin components being 0.569 (1):0.431 (1). PMID:26594402

  8. The Mechanism of Memory Enhancement of Acteoside (Verbascoside) in the Senescent Mouse Model Induced by a Combination of D-gal and AlCl3.

    PubMed

    Peng, Xiao-Ming; Gao, Li; Huo, Shi-Xia; Liu, Xin-Min; Yan, Ming

    2015-08-01

    Acteoside (verbsacoside), one of the main active phenylethanoid glycosides from Cistanche deserticola, is known to have antioxidant and neuroprotective activity, and herbs containing it are used to enhance memory. However, there is relatively little direct experimental evidence to support the use of acteoside in Alzheimer's disease (AD). The purpose of this study was to elucidate the effects of acteoside in improving learning and memory, using a mouse model of senescence induced by a combination of d-galactose and AlCl3 , and investigate its potential mechanisms compared with the positive controls vitamin E and piracetam. Acteoside was administered intragastrically at doses of 30, 60 and 120 mg/kg/day for 30 days after AD was induced. Memory function was evaluated using a step-down test. The number of neuron was analysed by haematoxylin and eosin staining and the number of Nissl bodies by Nissl staining. The expression of caspase-3 protein in hippocampus was detected by immunohistochemistry and western blot. Nitric oxide and total nitric oxide synthase level in hippocampus were also assessed. Our results showed that the latency of step down was shortened in AD model mice and the number of errors decreased after treatment with all doses of acteoside. Neurons and Nissl bodies in the hippocampus were increased significantly with higher doses (60 and 120 mg/kg/day) of acteoside. The content of nitric oxide, the activity of nitric oxide synthase and the expression of caspase-3 protein were decreased by 120 mg/kg/day acteoside compared with that of the AD model group. Our results support the results obtained previously using the Morris maze test in the same mouse model of senescence, and the use of traditional medicinal herbs containing acteoside for neuroprotection and memory loss.

  9. Supported-nanoparticle heterogeneous catalyst formation in contact with solution: kinetics and proposed mechanism for the conversion of Ir(1,5-COD)Cl/γ-Al2O3 to Ir(0)(~900)/γ-Al2O3.

    PubMed

    Mondloch, Joseph E; Finke, Richard G

    2011-05-25

    A current goal in heterogeneous catalysis is to transfer the synthetic, as well as developing mechanistic, insights from the modern revolution in nanoparticle science to the synthesis of supported-nanoparticle heterogeneous catalysts. In a recent study (Mondloch, J. E.; Wang, Q.; Frenkel, A. I.; Finke, R. G. J. Am. Chem. Soc. 2010, 132, 9701-9714), we initialized tests of the global hypothesis that quantitative kinetic and mechanistic studies, of supported-nanoparticle heterogeneous catalyst formation in contact with solution, can provide synthetic and mechanistic insights that can eventually drive improved syntheses of composition-, size-, and possibly shape-controlled catalysts. That study relied on the development of a well-characterized Ir(1,5-COD)Cl/γ-Al(2)O(3) precatalyst, which, when in contact with solution and H(2), turns into a nonaggregated Ir(0)(~900)/γ-Al(2)O(3) supported-nanoparticle heterogeneous catalyst. The kinetics of the Ir(1,5-COD)Cl/γ-Al(2)O(3) to Ir(0)(~900)/γ-Al(2)O(3) conversion were followed and fit by a two-step mechanism consisting of nucleation (A → B, rate constant k(1)) followed by autocatalytic surface growth (A + B → 2B, rate constant k(2)). However, a crucial, but previously unanswered question is whether the nucleation and growth steps occur primarily in solution, on the support, or possibly in both phases for one or more of the catalyst-formation steps. The present work investigates this central question for the prototype Ir(1,5-COD)Cl/γ-Al(2)O(3) to Ir(0)(~900)/γ-Al(2)O(3) system. Solvent variation-, γ-Al(2)O(3)-, and acetone-dependent kinetic data, along with UV-vis spectroscopic and gas-liquid-chromatography (GLC) data, are consistent with and strongly supportive of a supported-nanoparticle formation mechanism consisting of Ir(1,5-COD)Cl(solvent) dissociation from the γ-Al(2)O(3) support (i.e., from Ir(1,5-COD)Cl/γ-Al(2)O(3)), solution-based nucleation from that dissociated Ir(1,5-COD)Cl(solvent) species, fast Ir

  10. Experimental studies on BrO/Br ratios at Stromboli, Etna, Masaya, Gorely and Nyiragongo

    NASA Astrophysics Data System (ADS)

    Bobrowski, Nicole; Wittmer, Julian; Liotta, Marcello; Calabrese, Sergio; Giuffrida, Giovanni; Brusca, Lorenzo; Platt, Ulrich

    2014-05-01

    Since the discovery of BrO in a volcanic plume (Bobrowski et al. 2003) many measurements have been performed as well as modelling to understand the radical chemistry in volcanic plumes, in particular, the interaction between volcanic gas species, released under strongly reduced conditions, and the oxidizing atmosphere. Besides the goal in atmospheric chemistry to better determine the impact of volcanic emission (e.g. reactive bromine) on the local (and maybe global) scale, volcanologists also have an interest to understand if the BrO/SO2 ratios can be used as a monitoring parameter giving further insides in dynamic processes of volcanoes. One of the major advantages when utilizing BrO/SO2 ratios is the relatively easiness of the measurements, which can be taken in a safe distance from volcanic activity accompanied by a good temporal resolution partly even during explosive eruptions. Recently, it has been shown (Lübcke et al., 2013) that already existing automatically running measurement networks can now be used to gain long-term data sets of BrO/SO2 ratios. However, one of the arguments which potentially makes volcanological interpretations difficult is the reactivity of BrO. Therefore it is, of great importance to link the measurements of BrO and gaseous hydrogen bromide to the total emission flux of bromine in order to estimate the pristine gas composition released from magmas. In particular, meteorological influences, trace gas composition of the surrounding atmosphere and the volcanic gas composition can all potentially effect the formation of BrO and might have to be considered. Some of these factors potentially also influence near source in-situ measurement. We need to answer the question: Can we correlate BrO measurements to the total bromine outgassing? Only with this knowledge we can relate changes of the measured gas ratios (BrO/SO2) to the volcanic fluids emitted by the underlying magma and can interpret data as signals from depth, which provide insight

  11. Mixed valency of Cu, electron-mass enhancement, and three-dimensional arrangement of magnetic sites in the organic conductors (R1,R2-N,N'-dicyanoquinonediimine)2Cu (where R1,R2=CH3,CH3O,Cl,Br)

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Miyamoto, A.; Kato, R.; Sakai, F.; Kobayashi, A.; Yamakita, Y.; Furukawa, Y.; Tasumi, M.; Watanabe, T.

    1993-02-01

    The unique molecular conductors with pπ-d mixing band structures (R1,R2-N,N'-dicyanoquinonediimine)2Cu [(R1,R2-DCNQI)2Cu] (R1,R2=CH3,CH3O,Cl,Br) were examined. General features of the phase diagram of the DCNQI-Cu system were depicted. A region that is related to the existence of anomalously heavy-metal electrons has been found. The T2 dependence of the low-temperature resistivity of the alloyed system (DMe1-xMeBrx-DCNQI)2Cu (where Me=CH3) suggests a large enhancement of the electron mass at the critical situation where the system begins to exhibit a characteristic metal instability. The mixed valency of Cu (Cu+1.3) in (DMe-DCNQI)2Cu was confirmed by ir experiments performed on neutral DMe-DCNQI crystals and (DMe-DCNQI)2M (M=Li, Ba, Cu). The same conclusion was also derived from a low-temperature x-ray-diffraction experiment. The gradual temperature dependences of the ir absorption intensities of totally symmetric modes of (DBr-DCNQI)2Cu observed below the metal-insulator transition temperature (TMI) are in contrast with the discontinuous resistivity and susceptibility changes at TMI. This may be attributable to the existence of two driving forces characterizing the M-I transition. One is the sharp charge ordering in Cu sites and the other is the continuous development of charge-density waves on DCNQI stacks. The arrangement of Cu2+ and Cu+ below TMI was determined by an x-ray crystal-structure analysis of the threefold insulating phase of (MeBr-DCNQI)2Cu at 110 K. The nearest-neighbor Cu2+ ions interact with each other via two DCNQI molecules. A plausible spin structure of the antiferromagnetic ground state was proposed. According to this spin-structure model, the magnetic moments of Cu2+ along the crystallographic c axis will be arranged ferromagnetically.

  12. Characterization of the mouse ClC-K1/Barttin chloride channel.

    PubMed

    L'Hoste, Sébastien; Diakov, Alexei; Andrini, Olga; Genete, Mathieu; Pinelli, Laurent; Grand, Teddy; Keck, Mathilde; Paulais, Marc; Beck, Laurent; Korbmacher, Christoph; Teulon, Jacques; Lourdel, Stéphane

    2013-11-01

    Several Cl(-) channels have been described in the native renal tubule, but their correspondence with ClC-K1 and ClC-K2 channels (orthologs of human ClC-Ka and ClC-Kb), which play a major role in transcellular Cl(-) absorption in the kidney, has yet to be established. This is partly because investigation of heterologous expression has involved rat or human ClC-K models, whereas characterization of the native renal tubule has been done in mice. Here, we investigate the electrophysiological properties of mouse ClC-K1 channels heterologously expressed in Xenopus laevis oocytes and in HEK293 cells with or without their accessory Barttin subunit. Current amplitudes and plasma membrane insertion of mouse ClC-K1 were enhanced by Barttin. External basic pH or elevated calcium stimulated currents followed the anion permeability sequence Cl(-)>Br(-)>NO3(-)>I(-). Single-channel recordings revealed a unit conductance of ~40pS. Channel activity in cell-attached patches increased with membrane depolarization (voltage for half-maximal activation: ~-65mV). Insertion of the V166E mutation, which introduces a glutamate in mouse ClC-K1, which is crucial for channel gating, reduced the unit conductance to ~20pS. This mutation shifted the depolarizing voltage for half-maximal channel activation to ~+25mV. The unit conductance and voltage dependence of wild-type and V166E ClC-K1 were not affected by Barttin. Owing to their strikingly similar properties, we propose that the ClC-K1/Barttin complex is the molecular substrate of a chloride channel previously detected in the mouse thick ascending limb (Paulais et al., J Membr. Biol, 1990, 113:253-260).

  13. Modeling the observed tropospheric BrO background: Importance of multiphase chemistry and implications for ozone, OH, and mercury

    NASA Astrophysics Data System (ADS)

    Schmidt, J. A.; Jacob, D. J.; Horowitz, H. M.; Hu, L.; Sherwen, T.; Evans, M. J.; Liang, Q.; Suleiman, R. M.; Oram, D. E.; Le Breton, M.; Percival, C. J.; Wang, S.; Dix, B.; Volkamer, R.

    2016-10-01

    Aircraft and satellite observations indicate the presence of ppt (ppt ≡ pmol/mol) levels of BrO in the free troposphere with important implications for the tropospheric budgets of ozone, OH, and mercury. We can reproduce these observations with the GEOS-Chem global tropospheric chemistry model by including a broader consideration of multiphase halogen (Br-Cl) chemistry than has been done in the past. Important reactions for regenerating BrO from its nonradical reservoirs include HOBr