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Sample records for al br cl

  1. Theoretical studies of AlF, AlCl, and AlBr

    NASA Technical Reports Server (NTRS)

    Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Taylor, Peter R.

    1988-01-01

    Spectroscopic constants have been obtained for the lowest six singlet and lowest five triplet states of AlF and AlCl. The results suggest that the correct ordering of the triplet manifold in these molecules is: a 3Pi, b 3Sigma(+), c 3Sigma(+), d 3Pi, and e 3Delta. Radiative lifetimes have been determined for the excited states, and the A 1Pi to X 1Sigma(+) transition in AlF, AlCl, and AlBr has been examined in detail. A-X transition moment functions, Einstein coefficients, and A 1Pi vibrational lifetimes have been obtained for AlF and AlCl.

  2. 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.

  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. Raman spectra, ab initio molecular orbital calculations, vibrational analysis, and thermodynamic functions for NH/sub 3/:AlX/sub 3/ (X = F, Cl, Br)

    SciTech Connect

    Papatheodorou, G.N.; Curtiss, L.A.; Maroni, V.A.

    1983-03-15

    Raman spectra of gaseous NH/sub 3/:AlCl/sub 3/ and NH/sub 3/:AlBr/sub 3/ were recorded at 400 /sup 0/C. The observed Raman frequencies in combination with reported infrared frequencies for NH/sub 3/:AlCl/sub 3/ and ab initio molecular orbital calculations on NH/sub 3/:AlCl/sub 3/ and NH/sub 3/:AlF/sub 3/ were used to derive force constants for all three NH/sub 3/:AlX/sub 3/ complexes (X = F, Cl, Br) based on an adjusted valence force field (AVFF) concept. The resulting force constant calculations produced complete sets of A/sub 1/ and E mode frequencies for each complex. Statistical mechanical analyses were then performed using the A/sub 1/ and E mode frequencies together with estimated values for the torsional mode of each complex and published enthalpy data. From these analyses, the relative thermodynamic stability of each complex was determined. At 700 and 1000 K, NH/sub 3/:AlCl/sub 3/ was found to be more stable than NH/sub 3/:AlBr/sub 3/. It was further predicted that the reaction of gaseous NH/sub 3/ with solid AlF/sub 3/ to form NH/sub 3/:AlF/sub 3/ is not favored in this temperature range, which provides an explanation for the lack of success in prior efforts to produce NH/sub 3/:AlF/sub 3/.

  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. The role of Br2 and BrCl in surface ozone destruction at polar sunrise.

    PubMed

    Foster, K L; Plastridge, R A; Bottenheim, J W; Shepson, P B; Finlayson-Pitts, B J; Spicer, C W

    2001-01-19

    Bromine atoms are believed to play a central role in the depletion of surface-level ozone in the Arctic at polar sunrise. Br2, BrCl, and HOBr have been hypothesized as bromine atom precursors, and there is evidence for chlorine atom precursors as well, but these species have not been measured directly. We report here measurements of Br2, BrCl, and Cl2 made using atmospheric pressure chemical ionization-mass spectrometry at Alert, Nunavut, Canada. In addition to Br2 at mixing ratios up to approximately 25 parts per trillion, BrCl was found at levels as high as approximately 35 parts per trillion. Molecular chlorine was not observed, implying that BrCl is the dominant source of chlorine atoms during polar sunrise, consistent with recent modeling studies. Similar formation of bromine compounds and tropospheric ozone destruction may also occur at mid-latitudes but may not be as apparent owing to more efficient mixing in the boundary layer.

  7. Contributions of BrCl, Br2, BrOCl, Br2O, and HOBr to regiospecific bromination rates of anisole and bromoanisoles in aqueous solution.

    PubMed

    Sivey, John D; Bickley, Mark A; Victor, Daniel A

    2015-04-21

    When bromide-containing waters are chlorinated, conventional wisdom typically assumes HOBr is the only active brominating agent. Several additional and often-overlooked brominating agents (including BrCl, Br2, BrOCl, Br2O) can form in chlorinated waters, albeit at generally lower concentrations than HOBr. The extent to which these additional brominating agents influence bromination rates of disinfection byproduct precursors is, however, poorly understood. Herein, the influence of BrCl, Br2, BrOCl, Br2O, and HOBr toward rates of sequential bromination of anisole was quantified. Conditions affecting bromine speciation (e.g., pH, concentrations of chloride, bromide, and chlorine) were varied, and regiospecific second-order rate constants were calculated for reactions of each brominating agent with anisole, 2-bromoanisole, and 4-bromoanisole. The regioselectivity of anisole bromination changed with pH, consistent with the participation of more than one brominating agent. Under conditions representative of chlorinated drinking water, contributions to bromination rates decreased as BrCl > BrOCl > HOBr > Br2O (Br2 negligible). The second-order rate constant determined for net bromination of anisole by HOBr is up to 3000-times less than reported in previous studies (which assumed HOBr was the only active brominating agent). Accordingly, models that assume HOBr is the only kinetically relevant brominating agent in solutions of free bromine may be insufficient for reactions involving modestly nucleophilic organic compounds.

  8. 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+). PMID:25186362

  9. 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+).

  10. 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.

  11. Notizen: Raman-Spektroskopische Untersuchungen der Systeme ASCl3/Cl2-AlCl3 und AsCl3 /Cl2-GaCl3/ Raman Spectra of the Systems AsCl3/Cl2—AlCl3 and AsCl3/Cl2-GaCl3

    NASA Astrophysics Data System (ADS)

    Demircan, B.; Brockner, W.

    1983-07-01

    In the systems investigated only the compounds AsAlCl8 and AsGaCl8 g are found. Raman spectra were recorded for the solid and molten compounds and for mixtures with excess ASCl3 + CL2 and AlCl3 and GaCl3 , respectively. The observed frequencies are assigned to tetrahedral AsCl4+, AlCl4- and GaCl4- units. Melting of AsCl4AlCl 4 and AsCl4GaCl4 causes a decomposition into AsCl3 , Cl2 and AlCl3 and GaCl3 , respectively.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. Reaction cross sections and thermal rate constant for Cl(-) + CH3BrClCH3 + Br(-) from J-dependent quantum scattering calculations.

    PubMed

    Hennig, Carsten; Schmatz, Stefan

    2016-07-20

    Employing dimensionality-reduced time-independent quantum scattering theory and summation over all possible total angular momentum states, initial-state selected reaction cross sections for the exothermic gas-phase bimolecular nucleophilic substitution (SN2) reaction Cl(-) + CH3BrClCH3 + Br(-) have been calculated. The carbon-halogen bonds and the rotation of the methyl halides are taken into account. In agreement with previous calculations for J = 0, initial rotational motion of CH3Br decreases the reaction probability and consequently the cross sections. The experimentally obtained thermal rate constant for 300 K is reproduced within the experimental error. For lower temperatures, it is calculated to be below the experimental values but shows the same strong increase for T → 0. PMID:27381461

  19. Reaction cross sections and thermal rate constant for Cl(-) + CH3BrClCH3 + Br(-) from J-dependent quantum scattering calculations.

    PubMed

    Hennig, Carsten; Schmatz, Stefan

    2016-07-20

    Employing dimensionality-reduced time-independent quantum scattering theory and summation over all possible total angular momentum states, initial-state selected reaction cross sections for the exothermic gas-phase bimolecular nucleophilic substitution (SN2) reaction Cl(-) + CH3BrClCH3 + Br(-) have been calculated. The carbon-halogen bonds and the rotation of the methyl halides are taken into account. In agreement with previous calculations for J = 0, initial rotational motion of CH3Br decreases the reaction probability and consequently the cross sections. The experimentally obtained thermal rate constant for 300 K is reproduced within the experimental error. For lower temperatures, it is calculated to be below the experimental values but shows the same strong increase for T → 0.

  20. Theoretical investigation of structural properties of CuCl, CuBr and CuI compounds under hydrostatic pressure

    SciTech Connect

    Louhibi-Fasla, S.; Djabri, H. Rekab; Achour, H.; Kefif, K.

    2013-12-16

    We have applied a recent version of the full potential linear muffin-tin orbitals method (FPLMTO) to study the structural properties of copper halides CuX (X=Cl, Br, I) under high pressure using the generalized gradient approximation (GGA) for the exchange and correlation potential by Perdew et al. Results are given for lattice parameters, bulk modulus and its first derivatives in the wurtzite(B4), zinc-blende (B3), CsCl (B2), rock-salt (B1), and PbO (B10) structures. The results of these calculations are compared with the available theoretical and experimental data.

  1. Halogen systematics (Cl, Br, I) in Mid-Ocean Ridge Basalts: A Macquarie Island case study

    NASA Astrophysics Data System (ADS)

    Kendrick, Mark A.; Kamenetsky, Vadim S.; Phillips, David; Honda, Masahiko

    2012-03-01

    The abundance of halogens (Cl, Br and I) in the Earth's mantle has the potential to provide information about mantle metasomatism and volatile recycling in subduction zones. Basalt melts sample different parts of the Earth's mantle, but few data are available for Br or I in basalt melts, and the relative partitioning behaviour of these elements has not been investigated rigorously. To address these issues, we determined the abundances of Cl, Br and I in enriched Mid-Ocean Ridge Basalt (E-MORB) glasses from Macquarie Island in the southwest Pacific. The Macquarie Island glasses are fairly typical of Pacific MORB with MgO of ˜5.5. to 9 wt%, 87Sr/86Sr of 0.70257-0.70276, 143Nd/144Nd of 0.51300-0.51306 and 3He/4He of ˜8 Ra. These glasses provide a unique opportunity to investigate halogen partitioning behaviour, because their variable MgO contents and trace element signatures (e.g. La/Sm ˜1.4-7.9) result from different degrees of partial melting and fractional crystallisation. The combined measurement of Br/Cl, I/Cl and K/Cl, together with correlations between Cl and other trace elements, demonstrate that the halogens in the Macquarie Island glasses had a mantle source and were not influenced by seawater contamination. Log-log correlation diagrams indicate that Cl, Br and K were not statistically fractionated during partial melting, crystallisation or degassing of CO2 from these melts. The behaviour of I is less well constrained and minor fractionation of I/Cl cannot be precluded during multi-stage melting and enrichment processes. The data indicate the mantle source of the Macquarie Island glasses was characterised by K/Cl of 13 ± 4, Br/Cl of (3.7 ± 0.5) × 10-3 and I/Cl of (130 ± 100) × 10-6 (2σ uncertainties; weight ratios). The K/Cl ratio of the Macquarie Island glasses is equivalent to the median of all published MORB data. This suggests the Br/Cl and I/Cl values may also be representative of average MORB mantle values.

  2. 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.

  3. Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr toward dimethenamid in solutions of bromide + aqueous free chlorine.

    PubMed

    Sivey, John D; Arey, J Samuel; Tentscher, Peter R; Roberts, A Lynn

    2013-02-01

    HOBr, formed via oxidation of bromide by free available chlorine (FAC), is frequently assumed to be the sole species responsible for generating brominated disinfection byproducts (DBPs). Our studies reveal that BrCl, Br(2), BrOCl, and Br(2)O can also serve as brominating agents of the herbicide dimethenamid in solutions of bromide to which FAC was added. Conditions affecting bromine speciation (pH, total free bromine concentration ([HOBr](T)), [Cl(-)], and [FAC](o)) were systematically varied, and rates of dimethenamid bromination were measured. Reaction orders in [HOBr](T) ranged from 1.09 (±0.17) to 1.67 (±0.16), reaching a maximum near the pK(a) of HOBr. This complex dependence on [HOBr](T) implicates Br(2)O as an active brominating agent. That bromination rates increased with increasing [Cl(-)], [FAC](o) (at constant [HOBr](T)), and excess bromide (where [Br(-)](o)>[FAC](o)) implicate BrCl, BrOCl, and Br(2), respectively, as brominating agents. As equilibrium constants for the formation of Br(2)O and BrOCl (aq) have not been previously reported, we have calculated these values (and their gas-phase analogues) using benchmark-quality quantum chemical methods [CCSD(T) up to CCSDTQ calculations plus solvation effects]. The results allow us to compute bromine speciation and hence second-order rate constants. Intrinsic brominating reactivity increased in the order: HOBr ≪ Br(2)O < BrOCl ≈ Br(2) < BrCl. Our results indicate that species other than HOBr can influence bromination rates under conditions typical of drinking water and wastewater chlorination.

  4. Evaluation of LiCl-LiBr-KBr electrolyte for Li-alloy/metal disulfide cells

    SciTech Connect

    Kaun, T.D.

    1987-01-01

    The physical properties of a new molten salt electrolyte for lithium-alloy/metal disulfide cells, 25 mol % LiCl-37 mol % LiBr-38 mol % KBr, were investigated. Cyclic voltammetry of FeS/sub 2/ in the new molten salt at 375 to 425/sup 0/C indicated improved electrochemistry and stability of the reaction on the upper voltage plateau (1.75 V vs. LiAl). The new electrolyte provides an opportunity to operate an upper-plateau (UP) FeS/sub 2/ electrode at a lower temperature, 400/sup 0/C, and with a higher activity of lithium ion in the electrolyte. The broad liquidus of this molten salt at 400/sup 0/C also supports operation at high current density. Testing of 24- to 48-Ah cells indicated greater than 50% improved energy and power density over the conventional two-plateau FeS/sub 2/ cell with LiCl-KCl electrolyte. The conventional FeS/sub 2/ cells would lose 50% of their upper-plateau capacity within 200 cycles. The elimination of this capacity decline problem was demonstrated by 400 cycles and 5400 h of stable operation with a dense UP FeS/sub 2/ electrode cell, which maintained 89% utilization of theoretical capacity throughout the test.

  5. Four-dimensional quantum study on exothermic complex-forming reactions: Cl{sup -}+CH{sub 3}Br{yields}ClCH{sub 3}+Br{sup -}

    SciTech Connect

    Hennig, Carsten; Schmatz, Stefan

    2005-06-15

    The exothermic gas-phase bimolecular nucleophilic substitution (S{sub N}2) reaction Cl{sup -}+CH{sub 3}Br ({upsilon}{sub 1}{sup '},{upsilon}{sub 2}{sup '},{upsilon}{sub 3}{sup '}){yields}ClCH{sub 3} ({upsilon}{sub 1},{upsilon}{sub 2},{upsilon}{sub 3})+Br{sup -} and the corresponding endothermic reverse reaction have been studied by time-independent quantum scattering calculations in hyperspherical coordinates on a coupled-cluster potential-energy surface. The dimensionality-reduced model takes four degrees of freedom into account [Cl-C and C-Br stretching modes (quantum numbers {upsilon}{sub 3}{sup '} and {upsilon}{sub 3}); totally symmetric modes of the methyl group, i.e., C-H stretching ({upsilon}{sub 1}{sup '} and {upsilon}{sub 1}) and umbrella bending vibrations ({upsilon}{sub 2}{sup '} and {upsilon}{sub 2})]. Diagonalization of the Hamiltonian was performed employing the Lanczos algorithm with a variation of partial reorthogonalization. A narrow grid in the total energy was employed so that long-living resonance states could be resolved and extracted. While excitation of the reactant umbrella bending mode already leads to a considerable enhancement of the reaction probability, its combination with vibrational excitation of the broken C-Br bond, (0, 1, 1), results in a strong synergic effect that can be rationalized by the similarity with the classical transitional normal mode. Exciting the C-H stretch has a non-negligible effect on the reaction probability, while for larger translational energies this mode follows the expected spectatorlike behavior. Combination of C-Br stretch and symmetric C-H, (1,0,1), stretch does not show a cooperative effect. Contrary to the spectator mode concept, energy originally stored in the C-H stretching mode is by no means conserved, but almost completely released in other modes of the reaction products. Products are most likely formed in states with a high degree of excitation in the new C-Cl bond, while the internal modes of

  6. Energetic Diagrams and Structural Properties of Monohaloacetylenes HC≡CX (X = F, Cl, Br).

    PubMed

    Khiri, D; Hochlaf, M; Chambaud, G

    2016-08-01

    Highly correlated electronic wave functions within the Multi Reference Configuration Interaction (MRCI) approach are used to study the stability and the formation processes of the monohaloacetylenes HCCX and monohalovinylidenes C2HX (X = F, Cl, Br) in their electronic ground state. These tetra-atomics can be formed through the reaction of triatomic fragments C2F, C2Cl, and C2Br with a hydrogen atom or of C2H with halogen atoms via barrierless reactions, whereas the reactions between the diatomics [C2 + HX] need to overcome barriers of 1.70, 0.89, and 0.58 eV for X = F, Cl, and Br. It is found that the linear HCCX isomers, in singlet symmetry, are more stable than the singlet C2HX iso-forms by 1.995, 2.083, and 1.958 eV for X = F, Cl, and Br. The very small isomerization barriers from iso to linear forms are calculated 0.067, 0.044, and 0.100 eV for F, Cl, and Br systems. The dissociation energies of the HCCX systems (without ZPE corrections), resulting from the breaking of the CX bond, are calculated to be 5.647, 4.691, and 4.129 eV for X = F, Cl, Br, respectively. At the equilibrium geometry of the X(1)Σ(+) state of HCCX, the vertical excitation energies in singlet and triplet symmetries are all larger than the respective dissociation energies. Stable excited states are found only as (3)A', (3)A″, and (1)A″ monohalovinylidene structures.

  7. Trichloroethene and tetrachloroethene: tropospheric probes for Cl- and Br-atom reactions during the polar sunrise

    NASA Astrophysics Data System (ADS)

    Ariya, P. A.; Catoire, V.; Sander, R.; Niki, H.; Harris, G. W.

    1997-11-01

    We report the results of laboratory and modeling investigations of the atmospheric fate of chlorinated ethenes and their rôle as indicators of halogen reactions in the springtime Arctic troposphere. The kinetics and mechanism of the gas-phase reactions of Cl- and Br-atoms with tetrachloroethene were studied using a Fourier transform infrared spectrometer (FTIR) in 93.3kPa air and T = 296± 2 K. Along with our previous study on Cl and Br atom reactions of trichloroethene, using the known rate of the Cl + ethane reaction as reference, the values of 7.2±0.2×10-11 and 3.8±0.2×10-11 cm3 molecule-1 s-1 were obtained for the Cl-atom reaction rate constants of tri- and tetrachloroethene, respectively. For the Br-atom reactions, using ethene and propane as the reference molecules, we report the absolute values of 1.1±0.1×10-13 and 9.0±0.1×10-17 cm3 molecule-1 s-1 for the rates of Br attack on tri- and tetrachloroethene. The major products were XCl2C-C(O)Cl (X = H in trichloroethene and X = Cl in tetrachloroethene) and XBrClC-C(O)Cl in Cl-atom and Br-atom initiated reactions, respectively. We also observed phosgene and formyl chloride in the reactions of trichloroethene and phosgene in the tetrachloroethene reactions and report the branching ratios for these

  8. Extreme Cl/Br and δ37Cl isotope fractionation in fluids of modern submarine hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Lüders, Volker; Banks, David A.; Halbach, Peter

    2002-10-01

    Microthermometric studies of sphalerite-hosted fluid inclusions from fracture fillings in felsic igneous rocks of modern polymetallic massive sulfide mineralization from the JADE field (Central Okinawa Trough, Japan) and from mounds on the seafloor in the North Fiji basin reveal evidence for sub-critical two-phase separation of seawater. Chemical analyses of the fluid inclusions indicate intense water-rock interaction between the hydrothermal fluids and their host rocks. The analyses indicate that sub-critical phase separation has a much larger effect on the partitioning of chloride and bromide into liquid and vapor phase than previously reported for vent fluids. This study also shows that, for the first time, chlorine isotope fractionation correlates with Cl and Br fractionation. Using combined Cl/Br ratios and δ37Cl values allows us to discount Br-enriched organic matter or halite precipitation as responsible for the formation of Br-rich fluids. Moreover, the same parameters exclude any significant magmatic component in the mineral-forming fluids as previously proposed for similar modern sulfide deposits and other massive sulfide deposits in the geological record.

  9. 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.

  10. Radiative forcing calculations for CH{sub 3}Cl and CH{sub 3}Br

    SciTech Connect

    Grossman, A.S.; Grant, K.E.; Blass, W.E.; Wuebbles, D.J.

    1997-06-01

    Methyl chloride, CH{sub 3}Cl, and methyl bromide, CH{sub 3}Br, are particularly important in the global atmosphere as major natural sources of chlorine and bromine to the stratosphere. The production of these gases is dominated by natural sources, but smaller, important anthropogenic sources, such as agricultural fumigation and/or biomass burning, also exist. As absorbers of infrared radiation these gases are of interest for their potential effect on the tropospheric energy balance as well as for chemical interactions. In this study we estimate the radiative forcing and Global Warming Potentials (GWPs) of CH{sub 3}Cl and CH{sub 3}Br. Our calculations use an infrared radiative transfer model based on the correlated k-distribution algorithm for band absorption. Radiative forcing values of 0.0047W/m{sup 2} per part per billion by volume (ppbv) for CH{sub 3}Cl in the troposphere and 0.0049W/m{sup 2} per ppbv for CH{sub 3}Br in the troposphere were obtained. On a per molecule basis the radiative forcing values are about 2{percent} of the forcing of CFC-11 and about 270 times the forcing of CO{sub 2}. GWPs for these gases are about 8 for CH{sub 3}Cl and about 4 for CH{sub 3}Br (100 year time integration, CO{sub 2}=1). These results indicate that while CH{sub 3}Cl and CH{sub 3}Br have direct GWPs similar to that of CH{sub 4}, the current emission rates are too low to contribute meaningfully to atmospheric greenhouse heating effects.{copyright} 1997 American Geophysical Union

  11. High-performance acousto-optic materials - Hg2Cl2 and PbBr2

    NASA Technical Reports Server (NTRS)

    Gottlieb, Milton; Goutzoulis, Anastasios P.; Singh, N. B.

    1992-01-01

    New results achieved with recently grown Hg2Cl2 and PbBr2 crystals are described. With an optimized crystal growth technique Hg2Cl2 crystals were grown that show a significantly reduced acoustic attenuation compared to prior crystals, from 13.4 to 8 dB/microsec-GHz-squared. These crystals allow the development of Hg2Cl2 Bragg cells with time-bandwidth product figures in the 5100 to 6900 range, frequency operation as high as that for TeO2, and resolution about 25 percent higher than TeO2 for similar crystal lengths. PbBr2 crystals were also grown that exhibit a large figure of merit (M2 = 550) with an attenuation coefficient of 12 dB/microsec-GHz-squared. This material may be the choice for infrared devices where large diffraction efficiencies are needed.

  12. 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.

  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. Photoproduction of I2, Br2, and Cl2 on n-semiconducting powder

    NASA Technical Reports Server (NTRS)

    Reichman, B.; Byvik, C. E.

    1981-01-01

    The photosynthetic production of Br2 and Cl2 and the photocatalytic production of I2 from aqueous solutions of the respective halide ions in the presence of platinized semiconducting n-TiO2 powder are reported. Reactions were produced in 2-3 M oxygen-saturated aqueous solutions of KI, KBr or NaCl containing Pt-TiO2 powder which were irradiated by a high-pressure mercury lamp at a power of 400 mW/sq cm. Halogens are found to be produced in greater quantities when platinized TiO2 powders are used rather than pure TiO2, and rates of halogen production are observed to increase from Cl2 to Br2 to I2. The presence of the synthetic reactions producing Br2 and Cl2 with a net influx of energy indicates that an effective separation of the photoproduced electron-hole pair occurs in the semiconductor. Quantum efficiencies of the reaction, which increase with decreasing solution pH, are found to be as high as 30%, implying a solar-to-chemical energy conversion efficiency between 0.03% and 3% for the case of chlorine production. It is concluded that the photoproduction of halogens may be of practical value if product halogens are efficiently removed from the reaction cell.

  15. Br/Cl Ratios As Indicators Of The Origin Of Brines In The Alberta Basin, Canada

    NASA Astrophysics Data System (ADS)

    Gupta, I.; Wilson, A.

    2008-12-01

    Br/Cl ratios have been used to understand the origin and evolution of brines in sedimentary basins, but brines with similar Br/Cl compositions can form in a number of ways. In fact, despite having similar Br/Cl ratios, brines from the central Mississippi Salt Dome basin have been interpreted as derived from halite dissolution whereas the Alberta Basin brines have been interpreted as derived from evaporation of seawater past halite saturation. This study tests the uniqueness of the interpretations from Br/Cl ratios in one of the world's most widely studied sedimentary basins, the Alberta Basin, Canada, where considerable debate still exists about the residence times of brines in the basin. Geochemical evidence based on Br/Cl ratios suggests that brines in this basin have been preserved at depths for hundreds of millions of years, whereas hydrogeological models of topography driven flow in uplifted foreland basins suggest that brines in this type of setting can be completely flushed out in as little as 2 my. This project uses the 2D finite element FORTRAN code COMPACT to simulate variable-density fluid flow, heat transport, solute transport, and sediment compaction in tectonically evolving basins. COMPACT has been modified to add effects of erosion and sediment decompaction, and dissolution of evaporites (halite). Brine migration and groundwater age are simulated over the last 100 million years, along a 700 Km, east-west cross-section of the basin, using salinity and Br/Cl ratios as geochemical constraints. Our results suggest that, contrary to geochemical interpretations, halite dissolution has significantly contributed to the salinity distribution in the basin, and that the residence time of brines in the Alberta Basin has thus been overestimated. Model results from a wide range of sensitivity studies indicate that formation waters in this basin are not simple end members of a seawater evaporation model, but instead represent mixed signatures of brines formed by

  16. Electrical conductivity studies on CuBr containing Al2O3 particles

    NASA Technical Reports Server (NTRS)

    Dubec, P. M.; Wagner, J. B., Jr.

    1984-01-01

    The conductivity of CuBr was studied and the role of a second phase, Al2O3, dispersed in CuBr was tested. CuBr melts at 493 C and exhibits three phases in the solid state. CuBr is a good ionic conductor with a transport number for copper ions of virtually unity with weighed proportions of the appropriate chemicals used. The CuBr materials were heated above melting point of CuBr, and the samples were sandwiched between copper electrodes. The ac conductivity, was determined at 1 kHz between 25 and 440 C depending on the sample. It was shown that at low temperatures, the conductivity for CuBr (Al2O3) increased by as much as 100, whereas in the beta phase the conductivity of CuBr containing Al2O3 decreased. The electrical conductivity studies are in agreement with earlier data.

  17. Al(22)Cl(20).12L (L = THF, THP): the first polyhedral aluminum chlorides.

    PubMed

    Klemp, C; Bruns, M; Gauss, J; Häussermann, U; Stösser, G; van Wüllen, L; Jansen, M; Schnöckel, H

    2001-09-19

    Aluminum subhalides of the type Al(22)X(20).12L (X = Cl, Br; L = THF, THP) are the only known representatives of polyhedral aluminum subhalides and exhibit interesting multicenter bonding properties. Herein, we report on the synthesis and structural investigation of the first chlorides of this type. Additional investigations applying solid-state (27)Al NMR (MAS), XPS (of Al(4)Cp(4) and Al(22)X(20).12L), and quantum chemical calculations shed more light upon the structure of the molecules and possible Al modifications. PMID:11552817

  18. 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.

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

    PubMed

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

    2016-05-28

    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) cm(3) 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.

  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. Corrosion of type 316 stainless steel in molten LiF-LiCl-LiBr

    SciTech Connect

    Tortorelli, P.F.; DeVan, J.H.; Keiser, J.R.

    1981-01-01

    The properties of LiF-LiCl-LiBr salt make it attractive as a solvent for extracting tritium from a fusion reactor lithium blanket. Consequently, the corrosion of type 316 stainless steel by flowing (about 15 mm/s) LiF-LiCl-LiBr at a maximum temperature of 535/sup 0/C was studied to determine whether compatibility with the structural material would be limiting in such a system. The corrosion rate was found to be low (<2 ..mu..m/year) except immediately after the addition of a small amount of lithium metal to the salt. The lithium addition increased the corrosion rate to approx. 13.5 ..mu..m/year at 535/sup 0/C (approximately that of type 316 stainless steel exposed to lithium flowing at a similar velocity). At the proposed operating temperature (less than or equal to approx. 535/sup 0/C), however, it appears that type 316 stainless steel has acceptable compatibility with the tritium-processing salt LiF-LiCl-LiBr for use with a lithium blanket.

  2. Ionization energies of K2X (X=F, Cl, Br, I) clusters.

    PubMed

    Veličković, S R; Veljković, F M; Perić-Grujić, A A; Radak, B B; Veljković, M V

    2011-08-30

    The electronic structure and properties of dipotassiummonohalides are important for understanding the unique physical and chemical behavior of M(n)X systems. In the present study, K(2) X (here X=F, Cl, Br, I) clusters were generated in the vapor over salts of the corresponding potassium halide, using a magnetic sector thermal ionization mass spectrometer. The ionization energies obtained for K(2)F, K(2)Cl, K(2)Br, and K(2)I molecules were 3.82 ± 0.1 eV, 3.68 ± 0.1 eV, 3.95 ± 0.1 eV, and 3.92 ± 0.1, respectively. These experimental values of ionization energies for K(2) X (X=F, Br, and I) are presented for the first time. The ionization energy of K(2)Cl determined by thermal ionization corresponds to previous results obtained by photoionization mass spectrometry, and it agrees with the theoretical ionization energy calculated by the ab initio method. The presently obtained results support previous theoretical predictions that the excess electron in dipotassiummonohalide clusters is delocalized over two potassium atoms, which is characteristic for F-center clusters.

  3. Laser cooling of MgCl and MgBr in theoretical approach

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    Ab initio calculations for three low-lying electronic states (X2Σ+, A2Π, and 22Π) 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 f00 for A2Π3/2,1/2 (υ' = 0) → X2Σ+1/2 (υ″ = 0) are determined for both MgCl and MgBr molecules. Suitable radiative lifetimes τ of A2Π3/2,1/2 (υ' = 0) states for rapid laser cooling are also obtained. The proposed laser drives A2Π3/2 (υ' = 0) → X2Σ+1/2 (υ″ = 0) transition by using three wavelengths (main pump laser λ00; two repumping lasers λ10 and λ21). These results indicate the probability of laser cooling MgCl and MgBr molecules.

  4. 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.

  5. Photoelectron spectroscopy of AgCl, AgBr, and AgI vapors

    SciTech Connect

    Berkowitz, J.; Batson, C.H.; Goodman, G.L.

    1980-06-01

    He I photoelectron spectra of AgCl, AgBr and AgI vapors have been obtained which differ significantly from earlier work. In each instance, the characteristic features of the diatomic molecule are prominent. The spectral features separate into a valence region, predominantly halogen p-like, and a deeper region, predominantly of Ag 4d character. The latter is split by spin--orbit and ligand field interactions, which are parametrized from the experimental data. Relativistic calculations of the X/sub ..cap alpha../--DVM--SCC type have been performed for these species. At the transition state level, they agree very well with the experimental peak positions. Nonrelativistic calculations of this type have been performed for CuCl and cyclic Cu/sub 3/Cl/sub 3/. Unlike the AgX species, the CuCl and Cu/sub 3/Cl/sub 3/ exhibit strong mixing of metal d and halogen p orbitals for the uppermost occupied orbital, and other Cu 3d-like orbitals above the Cl 3p-like orbitals. It is suggested that the occurrence of Cu 3d orbitals in the valence region may play a role in the anomalous diagmagnetic signal and large conductivity changes of CuCl condensed from the vapor.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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. PMID:27112871

  11. Halogen-hydride interaction between Z-X (Z = CN, NC; X = F, Cl, Br) and H-Mg-Y (Y = H, F, Cl, Br, CH3).

    PubMed

    Mohajeri, Afshan; Alipour, Mojtaba; Mousaee, Mahboubeh

    2011-05-01

    Halogen-hydride interactions between Z-X (Z = CN, NC and X = F, Cl, Br) as halogen donor and H-Mg-Y (Y = H, F, Cl, Br, CH(3)) as electron donor have been investigated through the use of Becke three-parameter hybrid exchange with Lee-Yang-Parr correlation (B3LYP), second-order Møller-Plesset perturbation theory (MP2), and coupled-cluster single and double excitation (with triple excitations) [CCSD(T)] approaches. Geometry changes during the halogen-hydride interaction are accompanied by a mutual polarization of both partners with some charge transfer occurring from the electron donor subunit. Interaction energies computed at MP2 level vary from -1.23 to -2.99 kJ/mol for Z-F···H-Mg-Y complexes, indicating that the fluorine interactions are relatively very weak but not negligible. Instead, for chlorine- and bromine-containing complexes the interaction energies span from -5.78 to a maximum of -26.42 kJ/mol, which intimate that the interactions are comparable to conventional hydrogen bonding. Moreover, the calculated interaction energy was found to increase in magnitude with increasing positive electrostatic potential on the extension of Z-X bond. Analysis of geometric, vibrational frequency shift and the interaction energies indicates that, depending on the halogen, CN-X···H interactions are about 1.3-2.0 times stronger than NC-X···H interactions in which the halogen bonds to carbon. We also identified a clear dependence of the halogen-hydride bond strength on the electron-donating or -withdrawing effect of the substituent in the H-Mg-Y subunits. Furthermore, the electronic and structural properties of the resulting complexes have been unveiled by means of the atoms in molecules (AIM) and natural bond orbital (NBO) analyses. Finally, several correlative relationships between interaction energies and various properties such as binding distance, frequency shift, molecular electrostatic potential, and intermolecular density at bond critical point have been

  12. Electronic structures and geometries of the XF3 (X = Cl, Br, I, At) fluorides

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    The potential energy surfaces of the group 17 XF3 (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 C2v structures are computed for ClF3, BrF3, and IF3, while we predict that an average D3h structure would be experimentally observed for AtF3. Electron correlation and scalar relativistic effects strongly reduce the energy difference between the D3h geometry and the C2v one, along the XF3 series, and in the X = At case, spin-orbit coupling also slightly reduces this energy difference. AtF3 is a borderline system where the D3h 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 C2v minima, although both types of effects interfere.

  13. 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.

  14. 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.

  15. Electronic structures and geometries of the XF3 (X = Cl, Br, I, At) fluorides.

    PubMed

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

    2015-09-21

    The potential energy surfaces of the group 17 XF3 (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(2v) structures are computed for ClF3, BrF3, and IF3, while we predict that an average D(3h) structure would be experimentally observed for AtF3. Electron correlation and scalar relativistic effects strongly reduce the energy difference between the D(3h) geometry and the C(2v) one, along the XF3 series, and in the X = At case, spin-orbit coupling also slightly reduces this energy difference. AtF3 is a borderline system where the D(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(2v) minima, although both types of effects interfere.

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

    SciTech Connect

    Boehlke, 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{sup {minus}10} to 10{sup {minus}8} liter 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 {times} 10{sup {minus}3}); intermediate at St. Austell (0.85 {times} 10{sup {minus}3}), possibly representative of magmatic volatiles; and highest at Creede (1.5-2.1 {times} 10{sup {minus}3}) and Alleghany (1.2-2.4 {times} 10{sup {minus}3}). I/Cl mol ratios are lowest at Creede (1-14 {times} 10{sup {minus}6}); intermediate at Salton Sea (24-26 {times} 10{sup {minus}6}) and St. Austell (81 {times} 10{sup {minus}6}); and highest at Alleghany (320-940 {times} 10{sup {minus}6}). 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 information about sources of fluid salinity and provide excellent definition of fluid reservoirs and tracers of flow and interaction in ancient hydrothermal systems.

  17. The Electrochemical Co-reduction of Mg-Al-Y Alloys in the LiCl-NaCl-MgCl2-AlF3-YCl3 Melts

    NASA Astrophysics Data System (ADS)

    Li, Mei; Liu, Yaochen; Han, Wei; Wang, Shanshan; Zhang, Milin; Yan, Yongde; Shi, Weiqun

    2015-04-01

    The electrochemical formation of Mg-Al-Y alloys was studied in the LiCl-NaCl-MgCl2 melts by the addition of AlF3 and YCl3 on a molybdenum electrode at 973 K (700 °C). In order to reduce the volatilization of salt solvent in the electrolysis process, the volatile loss of LiCl-NaCl-MgCl2 and LiCl-KCl-MgCl2 melts was first measured in the temperature range from 873 K to 1023 K (600 °C to 750 °C). Then, the electrochemical behaviors of Mg(II), Al(III), Y(III) ions and alloy formation processes were investigated by cyclic voltammetry, chronopotentiometry, and open circuit chronopotentiometry. The cyclic voltammograms indicate that the under-potential deposition of magnesium and yttrium on pre-deposited Al leads to formation of Mg-Al and Al-Y intermetallic compounds. The Mg-Al-Y alloys were prepared by galvanostatic electrolysis in the LiCl-NaCl-MgCl2-AlF3-YCl3 melts and characterized by X-ray diffraction and scanning electron microscopy with energy dispersive spectrometry. Composition of the alloys was analyzed by inductively coupled plasma-atomic emission spectrometer, and current efficiency was also determined by the alloy composition.

  18. 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.

  19. 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.

  20. 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.

  1. Crystal growth of HfS 2 by chemical vapour transport with halogen (Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Fiechter, S.; Eckert, K.

    1988-05-01

    Single crystals of HfS 2 have been prepared by chemical vapour transport (CVT) with halogen. Depending on the transporting agent added, exergonic or endergonic transport was observed. Employing 0.5 mg/cm 3 chlorine or bromine in evacuated and sealed quartz ampoules, exergonic transport occurs. In a temperature gradient from 850 to 870 K transparent reddish-orange crystal platelets of pseudohexagonal shape (10×10×0.05 mm3) were obtained. Endergonic transport, found with iodine as transporting agent, first starts at higher temperatures (1270-1220 K). A thermochemical study of the vapour phase composition revealed that gaseous HfHal 4 and HfHal 3 ( Hal = Cl, Br) are responsible for the exergonic transport observed. Because of the higher stability of HfS 2 against iodine, CVT first starts at elevated temperatures. In the vapour phase Hfl and Hfl 2 dominate and effect a reversal of the transport direction.

  2. Structural and electronic properties of silicene on MgX₂ (X = Cl, Br, and I).

    PubMed

    Zhu, Jiajie; Schwingenschlögl, Udo

    2014-07-23

    Silicene is a monolayer of Si atoms in a two-dimensional honeycomb lattice, being expected to be compatible with current Si-based nanoelectronics. The behavior of silicene is strongly influenced by the substrate. In this context, its structural and electronic properties on MgX2 (X = Cl, Br, and I) have been investigated using first-principles calculations. Different locations of the Si atoms are found to be energetically degenerate because of the weak van der Waals interaction with the substrates. The Si buckling height is below 0.55 Å, which is close to the value of free-standing silicene (0.49 Å). Importantly, the Dirac cone of silicene is well preserved on MgX2 (located slightly above the Fermi level), and the band gaps induced by the substrate are less than 0.1 eV. Application of an external electric field and stacking can be used to increase the band gap.

  3. Groundwater nitrate contamination and use of Cl/Br ratio for source appointment.

    PubMed

    Samantara, M K; Padhi, R K; Satpathy, K K; Sowmya, M; Kumaran, P

    2015-02-01

    Source appointment for groundwater nitrate contamination is critical in prioritizing effective strategy for its mitigation. Here, we assessed the use of Cl/Br ratio and statistical correlation of hydro-chemical parameters to identify the nitrate source to the groundwater. A total of 228 samples from 19 domestic wells distributed throughout the study area were collected during June 2011-May 2012 and analyzed for various physicochemical parameters. Study area was divided into three spatial zones based on demographic features, viz., northern, southern, and central part. Nitrate concentration in 57 % of samples exceeded the prescribed safe limit for drinking stipulated by the World Health Organization (WHO) and Bureau of Indian standards (BIS). The central part of the study area showed elevated nitrate concentration ranging from below detection limit (BDL) to 263.5 mg/l as NO3 (-) and demonstrated high attenuation within the immediate vicinity thereby restricting diffusion of the nitrate to the adjacent parts. Resolution of correlation matrix as statistical indicator for nitrate contamination was poor. Seventy-seven percent of samples with high nitrate concentration (>45 mg/l as NO3 (-)) showed strong association with high Cl/Br mass ratio (350-900), indicating mixing of sewage and septic tank effluents with groundwater as a primary source for the nitrate in the studied area. Nitrate level during monsoon (BDL, 229.9 mg/l as NO3 (-)), post-monsoon (BDL, 263.5 mg/l as NO3 (-)), and pre-monsoon (0.5-223.1 mg/l as NO3 (-)) indicated additional contribution of surface leaching to groundwater.

  4. Groundwater nitrate contamination and use of Cl/Br ratio for source appointment.

    PubMed

    Samantara, M K; Padhi, R K; Satpathy, K K; Sowmya, M; Kumaran, P

    2015-02-01

    Source appointment for groundwater nitrate contamination is critical in prioritizing effective strategy for its mitigation. Here, we assessed the use of Cl/Br ratio and statistical correlation of hydro-chemical parameters to identify the nitrate source to the groundwater. A total of 228 samples from 19 domestic wells distributed throughout the study area were collected during June 2011-May 2012 and analyzed for various physicochemical parameters. Study area was divided into three spatial zones based on demographic features, viz., northern, southern, and central part. Nitrate concentration in 57 % of samples exceeded the prescribed safe limit for drinking stipulated by the World Health Organization (WHO) and Bureau of Indian standards (BIS). The central part of the study area showed elevated nitrate concentration ranging from below detection limit (BDL) to 263.5 mg/l as NO3 (-) and demonstrated high attenuation within the immediate vicinity thereby restricting diffusion of the nitrate to the adjacent parts. Resolution of correlation matrix as statistical indicator for nitrate contamination was poor. Seventy-seven percent of samples with high nitrate concentration (>45 mg/l as NO3 (-)) showed strong association with high Cl/Br mass ratio (350-900), indicating mixing of sewage and septic tank effluents with groundwater as a primary source for the nitrate in the studied area. Nitrate level during monsoon (BDL, 229.9 mg/l as NO3 (-)), post-monsoon (BDL, 263.5 mg/l as NO3 (-)), and pre-monsoon (0.5-223.1 mg/l as NO3 (-)) indicated additional contribution of surface leaching to groundwater. PMID:25638054

  5. 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.

  6. 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.

  7. Bonding in d9 complexes derived from EPR: Application to CuCl2-4, CuBr2-4, and CdCl2:Cu2+

    NASA Astrophysics Data System (ADS)

    Aramburu, J. A.; Moreno, M.

    1985-12-01

    In this work are reported the theoretical expressions for the [g], hyperfine, and superhyperfine (shf) tensors of a d9 square-planar complex within a molecular orbital (MO) scheme. These expressions include contributions arising from crystal field and charge transfer excitations calculated up to third and second order perturbations, respectively. This makes the present framework more general than those previously used. Through those expressions we have derived from the experimental EPR and optical data the MO coefficients corresponding to the valence b1g(x2-y2), b2g(xy), and eg(xz,yz) levels and also the core polarization contribution K to the hyperfine tensor for the systems CuCl2-4, CuBr2-4, and CdCl2:Cu2+. The 3d charge obtained for CuCl2-4 is equal to 0.61, 0.83, and 0.85 for the antibonding 3b1g, 2b2g, and 2eg levels, respectively. These figures are much closer to the Xα results by Bencini and Gatteschi [J. Am. Chem. Soc. 105, 5535 (1983)] than to those by Desjardins et al. [J. Am. Chem. Soc. 105, 4590 (1983)]. The σ and π covalency for CuBr2-4 are both higher than for CuCl2-4 in accord to the lower electronegativity for bromine. However, only for the antibonding 3b1g level of CuBr2-4 have we obtained an electronic charge lying mainly on ligands. The covalency of CdCl2:Cu2+ is smaller than that found for CuCl2-4, a fact associated to a higher metal-ligand distance for the former. Evidence of this statement are also given from the analysis of crystal-field spectra and isotropic shf constant. The values of K derived for CuCl2-4 (128.1×10-4 cm-1), CuBr2-4 (103.6×10-4 cm-1), and CdCl2:Cu2+ (123.9×10-4 cm-1) point out the dependence of K on the equatorial covalency but also on the existence of axial ligands. The [g] tensor of CuBr2-4 is dominated by the charge transfer contribution while the crystal field one is negative. Finally an analysis of the importance of each one of the involved contributions to the spin-Hamiltonian parameters is reported for the

  8. Dissociative adsorption of CH{sub 3}X (X = Br and Cl) on a silicon(100) surface revisited by density functional theory

    SciTech Connect

    Wang, Chen-Guang; Huang, Kai E-mail: wji@ruc.edu.cn; Ji, Wei E-mail: wji@ruc.edu.cn

    2014-11-07

    During the dissociative adsorption on a solid surface, the substrate usually participates in a passive manner to accommodate fragments produced upon the cleavage of the internal bond(s) of a (transient) molecular adsorbate. This simple picture, however, neglects the flexibility of surface atoms. Here, we report a Density Functional Theory study to revisit our early studies of the dissociative adsorption of CH{sub 3}X (X = Br and Cl) on Si(100). We have identified a new reaction pathway, which involves a flip of a silicon dimer; this new pathway agrees better with experiments. For our main exemplar of CH{sub 3}Br, insights have been gained using a simple model that involves a three-atom reactive center, Br-C-Si. When the silicon dimer flips, the interaction between C and Si in the Br-C-Si center is enhanced, evident in the increased energy-split of the frontier orbitals. We also examine how the dissociation dynamics of CH{sub 3}Br is altered on a heterodimer (Si-Al, Si-P, and Si-Ge) in a Si(100) surface. In each case, we conclude, on the basis of computed reaction pathways, that no heterodimer flipping is involved before the system transverses the transition state to dissociative adsorption.

  9. Temporal behavior of NO laser emission from the photodissociation of ClNO and BrNO

    SciTech Connect

    del Barrio, J.I.; Rebato, J.R.; Tablas, F.M.G.

    1986-06-15

    We have studied the temporal behavior of the NO laser emission produced from the photodissociation of ClNO and BrNO. No J shifting has been observed except in the 7..-->..6 band of /sup 2/Pi/sub 3//sub ///sub 2/ from ClNO. In both cases laser starts from an intermediate lasing vibrational level, triggering higher and lower transitions that end with the lowest observed band.

  10. The origin of the conductivity maximum in molten salts. II. SnCl2 and HgBr2

    NASA Astrophysics Data System (ADS)

    Aravindakshan, Nikhil P.; Kuntz, Colin M.; Gemmell, Kyle E.; Johnson, Keith E.; East, Allan L. L.

    2016-09-01

    The phenomenon of electrical conductivity maxima of molten salts versus temperature during orthobaric (closed-vessel) conditions is further examined via ab initio simulations. Previously, in a study of molten BiCl3, a new theory was offered in which the conductivity falloff at high temperatures is due not to traditional ion association, but to a rise in the activation energy for atomic ions hopping from counterion to counterion. Here this theory is further tested on two more inorganic melts which exhibit conductivity maxima: another high-conducting melt (SnCl2, σmax = 2.81 Ω-1 cm-1) and a low-conducting one (HgBr2, σmax = 4.06 × 10-4 Ω-1 cm-1). First, ab initio molecular dynamics simulations were performed and again appear successful in reproducing the maxima for both these liquids. Second, analysis of the simulated liquid structure (radial distributions, species concentrations) was performed. In the HgBr2 case, a very molecular liquid like water, a clear Grotthuss chain of bromide transfers was observed in simulation when seeding the system with a HgBr+ cation and HgBr3- anion. The first conclusion is that the hopping mechanism offered for molten BiCl3 is simply the Grotthuss mechanism for conduction, applicable not just to H+ ions, but also to halide ions in post-transition-metal halide melts. Second, it is conjectured that the conductivity maximum is due to rising activation energy in network-covalent (halide-bridging) melts (BiCl3, SnCl2, PbCl2), but possibly a falling Arrhenius prefactor (collision frequency) for molecular melts (HgBr2).

  11. The origin of the conductivity maximum in molten salts. II. SnCl2 and HgBr2.

    PubMed

    Aravindakshan, Nikhil P; Kuntz, Colin M; Gemmell, Kyle E; Johnson, Keith E; East, Allan L L

    2016-09-01

    The phenomenon of electrical conductivity maxima of molten salts versus temperature during orthobaric (closed-vessel) conditions is further examined via ab initio simulations. Previously, in a study of molten BiCl3, a new theory was offered in which the conductivity falloff at high temperatures is due not to traditional ion association, but to a rise in the activation energy for atomic ions hopping from counterion to counterion. Here this theory is further tested on two more inorganic melts which exhibit conductivity maxima: another high-conducting melt (SnCl2, σmax = 2.81 Ω(-1) cm(-1)) and a low-conducting one (HgBr2, σmax = 4.06 × 10(-4) Ω(-1) cm(-1)). First, ab initio molecular dynamics simulations were performed and again appear successful in reproducing the maxima for both these liquids. Second, analysis of the simulated liquid structure (radial distributions, species concentrations) was performed. In the HgBr2 case, a very molecular liquid like water, a clear Grotthuss chain of bromide transfers was observed in simulation when seeding the system with a HgBr(+) cation and HgBr3 (-) anion. The first conclusion is that the hopping mechanism offered for molten BiCl3 is simply the Grotthuss mechanism for conduction, applicable not just to H(+) ions, but also to halide ions in post-transition-metal halide melts. Second, it is conjectured that the conductivity maximum is due to rising activation energy in network-covalent (halide-bridging) melts (BiCl3, SnCl2, PbCl2), but possibly a falling Arrhenius prefactor (collision frequency) for molecular melts (HgBr2). PMID:27609001

  12. 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.

  13. Matrix photochemistry of syn-(chlorocarbonyl)sulfenyl bromide, syn-ClC(O)SBr: precursor to the novel species anti-ClC(O)SBr, syn-BrC(O)SCl, and BrSCl.

    PubMed

    Romano, R M; Védova, C O; Downs, A J; Greene, T M

    2001-06-20

    The vapor of (chlorocarbonyl)sulfenyl bromide, ClC(O)SBr, was isolated in solid Ar, Kr, N(2), and Ar doped with 5% CO at 15 K, and the matrix was subsequently irradiated with broad-band UV--visible light (200 < or = lambda < or = 800 nm), the changes being followed by reference to the IR spectrum of the matrix. The initial spectrum showed the vapor of ClC(O)SBr to consist of more than 99% of the syn form (with the C==O bond syn with respect to the S--Br bond) in equilibrium with less than 1% of the anti conformer. Irradiation caused various changes to occur. First, conformational randomization took place, leading to a roughly equimolar mixture of the two rotamers, and so affording the first spectroscopic characterization of an anti-ClC(O)S-containing compound. Simultaneously, the novel constitutional isomer syn-BrC(O)SCl was also formed. Continued photolysis resulted in the decay of all these species while revealing a third reaction channel, leading to the elimination of CO and the formation of the new triatomic sulfur halide BrSCl. The assignment of the IR bands to the different products was made on the basis of the usual criteria, taking account (i) of the effects of the naturally occurring isotopic pairs (35)Cl/(37)Cl and (79)Br/(81)Br, (ii) of the vibrational properties of related molecules, and (iii) of the properties predicted for the relevant molecules by quantum chemical calculations.

  14. Straightforward synthesis of [Au(NHC)X] (NHC = N-heterocyclic carbene, X = Cl, Br, I) complexes.

    PubMed

    Collado, Alba; Gómez-Suárez, Adrián; Martin, Anthony R; Slawin, Alexandra M Z; Nolan, Steven P

    2013-06-21

    An improved protocol for the synthesis of [Au(NHC)X] (X = Cl, Br, I) complexes is reported. This versatile one-step synthetic methodology proceeds under mild conditions, in air, using technical grade solvents, is scalable and is applicable to a wide range of imidazolium and imidazolidinium salts.

  15. Evaluation of production samples of the scintillators LaBr3:Ce andLaCl3:Ce

    SciTech Connect

    Choong, Woon-Seng; Derenzo, Stephen E.; Moses, William W.

    2005-09-15

    We report on the evaluation of the performance of two recently developed scintillator materials, LaCl{sub 3}:Ce and LaBr{sub 3}:Ce, at the task of gamma ray spectroscopy. Their performance is compared to a standard scintillator used for gamma ray spectroscopy--a 25 mm diameter 25 mm tall cylinder of NaI:Tl. We measure the pulse height, energy resolution, and full-energy efficiency of production LaBr{sub 3}:Ce and LaCl{sub 3}:Ce scintillation crystals of different sizes and geometries for a variety of gamma-ray energies. Using production rather than specially selected crystals will establish whether immediate large-scale use is feasible. The crystal is excited by gamma rays from one of six isotopic sources ({sup 125}I, {sup 241}Am, {sup 57}Co, {sup 22}Na, {sup 137}Cs, and {sup 60}Co) placed 15 cm away from the scintillator. Our measurements show that both LaCl{sub 3} and LaBr{sub 3} outperform NaI:Tl in almost all cases. They outperform NaI:Tl at all energies for the photopeak fraction and counting rate measurements, and for energy resolution at higher energies (above 200 keV for LaCl{sub 3} and 75 keV for LaBr{sub 3}). The performance of production crystals is excellent and these scintillators should be considered for immediate use in systems where stopping power and energy resolution are crucial.

  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. Stress corrosion cracking of Al-Li-Cu-Zr alloy 2090 in aqueous Cl sup minus and mixed CO sub 3 sup 2 minus /Cl sup minus environments

    SciTech Connect

    Buchheit, R.G. ); Wall, F.D.; Stoner, G.E. . Dept. of Materials Science); Moran, J.P. )

    1991-01-01

    A comparison of the short-transverse SCC behavior of 2090 in pH 5.5 Cl{sup {minus}} and alkaline CO{sub 3}{sup 2 {minus}}/Cl{sup {minus}} solutions using a static load smooth bar SCC technique was made. In the alkaline CO{sub 3}{sup 2 {minus}}/Cl{sup {minus}} solutions, E{sub br} for the {alpha}-Al matrix phase was 0.130 V more positive than the E{sub br} of the subgrain boundary T{sub 1} phase. In this environment, stress corrosion cracking test specimens subjected to potentials in the window defined by the two breakaway potentials failed along an intersubgranular path in less than an hour. In the Cl{sup {minus}} environment, the E{sub br} values for the two phases were nearly equal and this rapid SCC condition could not be satisfied; accordingly SCC failures were not observed. Rapid SCC failure of 2090 in CO{sub 3}{sup 2 {minus}}/Cl{sup {minus}} in our static load, constant immersion experiments appear to be related to recently reported pre-exposure embrittlement'' failures induced by immersing stressed specimens removed into ambient laboratory air after immersion in aerated NaCl solution for 7 days. In those experiments, specimens failed in less than 24 hours after removal from solution. Our polarization experiments have shown that the corrosion behavior of T{sub 1}, CO{sub 3}{sup 2 {minus}}/Cl{sup {minus}} environments, but the {alpha}-Al phase crack walls, is rapidly passivated. X-ray diffraction of the films which formed in simulated crevices suggests that this passivating film belongs to a class of compounds known as hydrotalcites.

  18. 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

  19. 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. PMID:27156887

  20. Reaction dynamics of methane with F, O, Cl, and Br on ab initio potential energy surfaces.

    PubMed

    Czakó, Gábor; Bowman, Joel M

    2014-04-24

    The bimolecular hydrogen abstraction reactions of methane with atoms have become benchmark systems to test and extend our knowledge of polyatomic chemical reactivity. We review the state-of-the-art methodologies for reaction dynamics computations of X + methane [X = F, O((3)P), Cl, Br] reactions, which consist of two key steps: (1) potential energy surface (PES) developments and (2) reaction dynamics computations on the PES using either classical or quantum methods. We briefly describe the permutationally invariant polynomial approach for step 1 and the quasiclassical trajectory method, focusing on the mode-specific polyatomic product analysis and the Gaussian binning (1GB) techniques, and reduced-dimensional quantum models for step 2. High-quality full-dimensional ab initio PESs and dynamical studies of the X + CH4 and CHD3 reactions are reviewed. The computed integral cross-sections, angular, vibrational, and rotational product distributions are compared with available experiments. Both experimental and theoretical findings shed light on the rules of mode-selective polyatomic reactivity.

  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. Subduction-related halogens (Cl, Br and I) and H2O in magmatic glasses from Southwest Pacific Backarc Basins

    NASA Astrophysics Data System (ADS)

    Kendrick, Mark A.; Arculus, Richard J.; Danyushevsky, Leonid V.; Kamenetsky, Vadim S.; Woodhead, Jon D.; Honda, Masahiko

    2014-08-01

    Submarine magmatic glasses from the Manus, Woodlark, North Fiji and Lau backarc basins in the Southwest Pacific, and Volcano A on the volcanic front of the Tonga Arc adjacent to the Lau Basin, were investigated to characterise the Cl, Br and I elemental budgets in subduction systems. In particular we seek to determine the extent of variability in the Br/Cl and I/Cl ratios of backarc basin basalts (BABB) and evaluate if these ratios could improve constraints on the source of subducted volatile components in backarc basins worldwide. The selected glasses represent variably evolved melts of boninite, basalt, basaltic-andesite, dacite and rhyolite composition and were selected from spreading centres and seamounts located at varying distances from the associated arcs. In general the strongest subduction signatures (e.g. Ba/Nb of 100-370) occur in the samples closest to the arcs and lower more MORB-like Ba/Nb of <16 are found in the more distal samples. The glasses investigated have extremely variable halogen concentrations (e.g. 3-4200 ppm Cl), with the highest concentrations in enriched glasses with the most evolved compositions. As observed in previous studies, the K/Cl, Br/Cl and I/Cl ratios of glasses from individual settings do not vary as a function of MgO and are considered representative of the magma sources because these ratios are not easily altered by partial melting or fractional crystallisation. Systematic variations in these ratios between basins can therefore be related to mixing of halogens from different sources including: (i) the mantle wedge which has MORB-like Br/Cl and I/Cl; (ii) a subduction-derived slab fluid with estimated salinity of ∼4-10 wt% salts and variable I/Cl; and (iii) brines characterised by salinities of 55±15 wt% salts and Br/Cl slightly higher than seawater, that are sometimes assimilated in crustal magma chambers. The slab fluids enriching the Woodlark Basin, North Fiji Basin and the Fonualei Spreading Centre of the Lau Basin

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

    NASA Technical Reports Server (NTRS)

    Cherng, Jing-Yih; Bennion, Douglas N.

    1987-01-01

    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.

  4. 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}.

  5. 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.

  6. Production mechanisms of molecular Cl2, Br2, and I2 from the multiphase oxidation of halide-ice surfaces

    NASA Astrophysics Data System (ADS)

    Halfacre, J. W.; Shepson, P. B.; Slade, J. H.

    2015-12-01

    The release of molecular halogens (particularly Cl2, Br2, and I2) into the Arctic boundary layer can cause the rapid and episodic depletion of surface-level ozone, thus altering the oxidation capacity of the atmosphere. These halogens have long been believed to primarily originate from frozen, saline surfaces, and direct production has been recently observed in situ. However, the oxidation mechanisms responsible for this halogen production remain unclear. Here, we present results from a series of laboratory experiments in which gas-phase Cl2, Br2, and I2 production was observed from the multiphase oxidation of frozen, simulated seawater solutions. For this study, we employed a coated-wall flow tube coupled to a chemical ionization mass spectrometer, and tested the effects of varying the solution pH and halogen oxidant (including O3, NO2-, N2O5, and HOOH).

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. The effects of CaCl2 and CaBr2 on the reproduction of Daphnia magna Straus.

    PubMed

    Mažuran, Neda; Hršak, Vladimir; Kovačević, Goran

    2015-06-01

    Concentrated CaCl2 and CaBr2 salt solutions of densities up to 2.3 kg L-1 are regularly used to control hydrostatic pressure in oil wells during special operations in the exploration and production of natural gas and crude oil. Various concentrations of high density salts are frequently left in mud pits near the drilling site as waste, polluting fresh and ground waters by spillage and drainage. The toxic effects of these salts have already been observed. This study investigated the effects of CaCl2 and CaBr2 on water flea Daphnia magna Straus in a 21-day reproduction test. The three tested concentrations of CaCl2 (240, 481, and 1925 mg L-1) caused a significant dose-response decrease of reproduction (p<0.001). With CaBr2 (533 and 1066 mg L-1), only aborted eggs were produced, demonstrating the embryotoxicity of the substance. The results suggest that high concentrations of the tested chemicals are harmful to Daphnia's reproduction and could reduce its abundance. PMID:26110475

  12. Rate constants for the reactions of OH with CH3Cl, CH2Cl2, CHCl3, and CH3Br

    NASA Technical Reports Server (NTRS)

    Hsu, K.-J.; Demore, W. B.

    1994-01-01

    Rate constants for the reactions of OH with CH3Cl, CH2Cl2, CHCl3, and CH3Br have been measured by a relative rate technique in which the reaction rate of each compound was compared to that of HFC-152a (CH3CHF2) and (for CH2Cl2) HFC-161 (CH3CH2F). Using absolute rate constants for HFC-152a and HFC-161, which we have determined relative to those for CH4, CH3CCl3, and C2H6, temperature dependent rate constants of both compounds were derived. The derived rate constant for CH3Br is in good agreement with recent absolute measurements. However, for the chloromethanes all the rate constants are lower at atmospheric temperatures than previously reported, especially for CH2Cl2 where the present rate constant is about a factor of 1.6 below the JPL 92-20 value. The new rate constant appears to resolve a discrepancy between the observed atmospheric concentrations and those calculated from the previous rate constant and estimated release rates.

  13. 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.

  14. Freeze-dried PVP-Ag+ precursors to novel AgBr/AgCl-Ag hybrid nanocrystals for visible-light-driven photodegradation of organic pollutants

    NASA Astrophysics Data System (ADS)

    Chen, Deliang; Chen, Qianqian; Zhang, Wenjie; Ge, Lianfang; Shao, Gang; Fan, Bingbing; Lu, Hongxia; Zhang, Rui; Yang, Daoyuan; Shao, Guosheng

    2015-04-01

    AgBr/AgCl-Ag nanocrystals with various molar Br-to-Ag ratios (RBr/Ag = 0, 1/3, 1/2, 2/3, 1) and different photoreduction times (0-20 min) were synthesized via stepwise liquid-solid reactions using the freeze-dried PVP-Ag+ hybrid as the Ag source, followed by a photoreduction reaction. The AgBr/AgCl-Ag7.5(1:2) nanocrystals obtained take on a spherical morphology with a particle-size range of 58 ± 15 nm. The photocatalytic performance of AgBr/AgCl-Ag nanocrystals was evaluated by photodegrading organic dyes, 4-chlorophenol and isopropanol under artificial visible light (λ ⩾ 420 nm, 100 mW cm-2). For the decomposition of rhodamine B, the AgBr/AgCl-Ag7.5(1:2) nanocrystals has a photodegradation rate of ∼0.87 min-1, ∼159 times higher than that (∼0.0054 min-1) of TiO2 (P25), whereas the AgCl-Ag and AgBr-Ag nanocrystals have photodegradation rates of 0.35 min-1 and 0.45 min-1, respectively. The efficient separation of photogenerated electron-hole pairs in the ternary system consisting of AgBr, AgCl and Ag species plays a key role in the enhancement of photocatalytic performance.

  15. Electrochemistry of selenium in a basic AlCl{sub 3}-NaCl melt

    SciTech Connect

    Matsunaga, M.; Morimitsu, M.; Hosokawa, K.

    1995-09-01

    Sodium/molten-salt secondary batteries composed of a liquid sodium and chloroaluminate melt have been widely studied for electric vehicle and load-leveling applications. The authors have been interested in developing new cathode materials to be used in this type of battery. The electrochemical reactions of selenium species in a basic AlCl{sub 3}-NaCl melt has been studied by measuring EMF of an Na/SeCl{sub 4} cell. The reaction mechanism between elemental and tetravalent selenium consists of at least four electrochemical steps, including intermediates such as Se{sup 2+}, Se{sub 2}{sup 2+}, and Se{sub 8}{sup 2+}. The reaction sequence from Se{sup 4+} to Se{sub 8}{sup 2+} is discussed. The formal potential for each reaction is also determined.

  16. Electronic properties of PbX₃CH₃NH₃ (X = Cl, Br, I) compounds for photovoltaic and photocatalytic applications.

    PubMed

    Melissen, Sigismund Teunis Alexander George; Labat, Frédéric; Sautet, Philippe; Le Bahers, Tangui

    2015-01-21

    Since the discovery of their excellent performance as the light-absorbing semiconducting component in photovoltaic cells, the PbX3CH3NH3 (X = I, Br, Cl) perovskites have received renewed attention. The five polymorphs stable above 200 K - the tetragonal phases for X = I, Br, Cl and the cubic phases for X = I, Br - were studied using periodic DFT calculations involving hybrid functionals (PBE0 and HSE), employing Gaussian-type orbitals as well as plane waves and including relativistic effects (spin-orbit coupling). The influence of the halogen substitution and of the crystal phase on these properties is analysed by comparing the properties obtained in this study to the experimental ones and to the theoretical ones computed using other methods. We show that an accurate treatment of these systems requires the description of dispersion forces and spin-orbit coupling. The different time scales for the electronic and vibrational components of the polarizability inspire the hypothesis that several interfacial charge transfer mechanisms are encountered in the working principle of the photovoltaic devices involving these perovskite materials. The heavy elements in the structure (Pb, I) play a major role in the high polarizability and the low effective charge carrier masses and hence in the low exciton binding energies and the high charge mobility. This systematic work on the PbX3CH3NH3 family offers to theoreticians an overview of the landscape of quantum chemical methods to enable a reasonable choice of methodology for studying these systems.

  17. 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.

  18. Comparative study of magnetotransport properties and structural features of the organic superconductors κ'-(BEDT-TTF) 2Cu[N(CN) 2]X, where X = Cl, Br

    NASA Astrophysics Data System (ADS)

    Zverev, Vladimir; Manakov, Andrey; Khasanov, Salavat; Shibaeva, Rimma; Kushch, Natalia; Kazakova, Anna; Yagubskii, Eduard

    2008-12-01

    The crystal structure, the resistivity and the upper critical field of radical cation salts κ'-(BEDT-TTF) 2Cu[N(CN) 2]X, where X = Cl, Br (κ'-X hereafter), have been studied. Both κ'-Br and κ'-Cl samples were superconductors with Tc lying in the interval 11.3-11.9 K and had the unit cell volume smaller than that for κ-Br and κ-Cl, respectively. The temperature dependence of interlayer resistivity ρ⊥ for κ'-Br is characterized by the hump lying in the temperature interval 35-100 K. For κ'-Cl ρ⊥ is considerably smaller and goes down monotonously with the temperature. The curves Hcr( T) for all crystals demonstrate a non-BCS-behaviour for both in-plane and out-of-plane magnetic field orientations.

  19. 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

  20. 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.

  1. Energetics of C-F, C-Cl, C-Br, and C-I bonds in 2-haloethanols. enthalpies of formation of XCH(2)CH(2)OH (X = F, Cl, Br, I) compounds and of the 2-hydroxyethyl radical.

    PubMed

    Bernardes, Carlos E S; Minas da Piedade, Manuel E; Amaral, Luísa M P F; Ferreira, Ana I M C L; Ribeiro da Silva, Manuel A V; Diogo, Hermínio P; Costa Cabral, Benedito J

    2007-03-01

    The energetics of the C-F, C-Cl, C-Br, and C-I bonds in 2-haloethanols was investigated by using a combination of experimental and theoretical methods. The standard molar enthalpies of formation of 2-chloro-, 2-bromo-, and 2-iodoethanol, at 298.15 K, were determined as Delta(f)H(degree)m(CH2CH2OH, l) = -315.5 +/- 0.7 kJ.mol-1, Delta(f)H(degree)mBrCH2CH2OH, l) = -275.8 +/- 0.6 kJ.mol-1, Delta(f)H(degree)m(ICH2CH2OH, l) = -207.3 +/- 0.7 kJ.mol-1, by rotating-bomb combustion calorimetry. The corresponding standard molar enthalpies of vaporization, Delta(vap)H(degree)m(ClCH2CH2OH) = 48.32 +/- 0.37 kJ.mol-1, Delta(vap)H(degree)m(BrCH2CH2OH) = 54.08 +/- 0.40 kJ.mol-1, and Delta(vap)H(degree)m(ICH2CH2OH) = 57.03 +/- 0.20 kJ.mol-1 were also obtained by Calvet-drop microcalorimetry. The condensed phase and vaporization enthalpy data lead to Delta(f)H(degree)m(ClCH2CH2OH, g) = -267.2 +/- 0.8 kJ.mol-1, Delta(f)H(degree)m(BrCH2CH2OH, g) = -221.7 +/- 0.7 kJ.mol-1, and Delta(f)H(degree)m(ICH2CH2OH, g) = -150.3 +/- 0.7 kJ.mol-1. These values, together with the enthalpy of selected isodesmic and isogyric gas-phase reactions predicted by density functional theory (B3LYP/cc-pVTZ) and CBS-QB3 calculations were used to derive the enthalpies of formation of gaseous 2-fluoroethanol, Delta(f)H(degree)m(FCH2CH2OH, g) = -423.6 +/- 5.0 kJ.mol-1, and of the 2-hydroxyethyl radical, Delta(f)H(degree)m(CH2CH2OH, g) = -28.7 +/- 8.0 kJ.mol-1. The obtained thermochemical data led to the following carbon-halogen bond dissociation enthalpies: DHo(X-CH2CH2OH) = 474.4 +/- 9.4 kJ.mol-1 (X = F), 359.9 +/- 8.0 kJ.mol-1 (X = Cl), 305.0 +/- 8.0 kJ.mol-1 (X = Br), 228.7 +/- 8.1 kJ.mol-1 (X = I). These values were compared with the corresponding C-X bond dissociation enthalpies in XCH2COOH, XCH3, XC2H5, XCH=CH2, and XC6H5. In view of this comparison the computational methods mentioned above were also used to obtain Delta(f)H(degree)m-594.0 +/- 5.0 kJ.mol-1 from which DHo(F-CH2COOH) = 435.4 +/- 5.4 kJ.mol-1

  2. 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.

  3. 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.

  4. D(5h) C50X10: saturn-like fullerene derivatives (X=F, Cl, Br).

    PubMed

    Chang, Y F; Zhang, J P; Hong, B; Sun, H; An, Z; Wang, R S

    2005-09-01

    Based on the recently reported D(5h) C(50), the geometries and stabilities of its Saturn-like derivatives C(50)X(10) (X=F, Cl, Br) have been investigated by DFT method. Compared with C(50), the equatorial carbon atoms in C(50)X(10) have been saturated by halogens and change to sp(3) hybridization to release the large angle strain. Because the equatorial carbon atoms have been taken out of the pi system by the halogens "ring," the C(50)X(10) system has been split into two well-delocalized conjugated annulene subunits, and then the electronic stabilization has been enhanced.

  5. Allylic and Allenic Halide Synthesis via NbCl5- and NbBr5-Mediated Alkoxide Rearrangements

    PubMed Central

    Ravikumar, P. C.; Yao, Lihua; Fleming, Fraser F.

    2009-01-01

    Addition of NbCl5, or NbBr5, to a series of magnesium, lithium, or potassium allylic or propargylic alkoxides directly provides allylic or allenic halides. Halogenation formally occurs through a metalla-halo-[3,3] rearrangement although concerted, ionic, and direct displacement mechanisms appear to operate competitively. Transposition of the olefin is equally effective for allylic alkoxides prepared by nucleophilic addition, deprotonation, or reduction. Experimentally, the niobium pentahalide halogenations are rapid, afford essentially pure E-allylic or allenic halides after extraction, and are applicable to a range of aliphatic and aromatic alcohols, aldehydes, and ketones. PMID:19739606

  6. Allylic and allenic halide synthesis via NbCl(5)- and NbBr(5)-mediated alkoxide rearrangements.

    PubMed

    Ravikumar, P C; Yao, Lihua; Fleming, Fraser F

    2009-10-01

    Addition of NbCl(5) or NbBr(5) to a series of magnesium, lithium, or potassium allylic or propargylic alkoxides directly provides allylic or allenic halides. Halogenation formally occurs through a metalla-halo-[3,3] rearrangement, although concerted, ionic, and direct displacement mechanisms appear to operate competitively. Transposition of the olefin is equally effective for allylic alkoxides prepared by nucleophilic addition, deprotonation, or reduction. Experimentally, the niobium pentahalide halogenations are rapid, afford essentially pure (E)-allylic or -allenic halides after extraction, and are applicable to a range of aliphatic and aromatic alcohols, aldehydes, and ketones. PMID:19739606

  7. 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.

  8. Ring-strain release in neutral and dicationic 7,8,17,18-tetra-bromo-5,10,15,20-tetra-phenyl-porphyrin: crystal structures of C44H26Br4N4 and C44H28Br4N4 (2+)·2ClO4 (-)·3CH2Cl2.

    PubMed

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

    2016-06-01

    Two porphyrin complexes were studied to determine the effects of protonation on ring deformation within the porphyrin. The porphyrin 7,8,17,18-tetra-bromo-5,10,15,20-tetra-phenyl-porphyrin, 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 di-chloro-methane tris-olvate, C44H28Br4N4 (2+)·2ClO4 (-)·3CH2Cl2. The centrosymmetric neutral species is observed to have a mild 'ruffling' of the pyrrole rings and is essentially planar throughout; intra-molecular 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

  9. Silicene/germanene on MgX2 (X = Cl, Br, and I) for Li-ion battery applications

    NASA Astrophysics Data System (ADS)

    Zhu, Jiajie; Chroneos, Alexander; Schwingenschlögl, Udo

    2016-03-01

    Silicene is a promising electrode material for Li-ion batteries due to its high Li capacity and low Li diffusion barrier. Germanene is expected to show a similar performance due to its analogous structural and electronic properties. However, the performance of both the materials will be determined by the substrate, since freestanding configurations are unstable. We propose Si/MgX2 and Ge/MgX2 (X = Cl, Br, and I) as suitable hybrid structures, based on first-principles calculations. We find that Li will not cluster and that the Li capacity is very high (443 and 279 mA h g-1 for silicene and germanene on MgCl2, respectively). Sandwich structures can be used to further enhance the performance. Low diffusion barriers of less than 0.3 eV are predicted for all the hybrid structures.

  10. The rare-earth metal carbide halide superconductors RE 2C 2X 2 (RE=Y, La; X=Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Kremer, R. K.; Ahn, K.; Henn, R. W.; Mattausch, Hj; Schnelle, W.; Stolovits, A.; Simon, A.

    1999-05-01

    Superconductivity in layered yttrium carbide bromides and iodides with transition temperatures ranging up to 11.6 K is achieved by adjusting the Br:I, ratio to ≈1:3 in phases of Y 2C 2(Br,I) 2. In our contribution, we compile basic physical and chemical properties of Y 2C 2X 2 (X=Cl, Br, I) and present new results of the La-based phases La 2C 2X 2 (X=Br, I).

  11. Br{sub 2} molecular elimination in 248 nm photolysis of CHBr{sub 2}Cl by using cavity ring-down absorption spectroscopy

    SciTech Connect

    Wei Peiying; Chang Yuanping; Lee Yushan; Lee Weibin; Lin Kingchuen; Chen, K. T.; Chang, A. H. H.

    2007-01-21

    Elimination of molecular bromine is probed in the B {sup 3}{pi}{sub ou}{sup +}<-X {sup 1}{sigma}{sub g}{sup +} transition following photodissociation of CHBr{sub 2}Cl at 248 nm by using cavity ring-down absorption spectroscopy. The quantum yield for the Br{sub 2} elimination reaction is determined to be 0.05{+-}0.03. The nascent vibrational population ratio of Br{sub 2}(v=1)/Br{sub 2}(v=0) is obtained to be 0.5{+-}0.2. A supersonic beam of CHBr{sub 2}Cl is similarly photofragmented and the resulting Br atoms are monitored with a velocity map ion-imaging detection, yielding spatial anisotropy parameters of 1.5 and 1.1 with photolyzing wavelengths of 234 and 267 nm, respectively. The results justify that the excited state promoted by 248 nm should have an A{sup ''} symmetry. Nevertheless, when CHBr{sub 2}Cl is prepared in a supersonic molecular beam under a cold temperature, photofragmentation gives no Br{sub 2} detectable in a time-of-flight mass spectrometer. A plausible pathway via internal conversion is proposed with the aid of ab initio potential energy calculations. Temperature dependence measurements lend support to the proposed pathway. The production rates of Br{sub 2} between CHBr{sub 2}Cl and CH{sub 2}Br{sub 2} are also compared to examine the chlorine-substituted effect.

  12. 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.

  13. Periodicity, Electronic Structures, and Bonding of Gold Tetrahalides [AuX4]- (X = F, Cl, Br, I, At, Uus).

    PubMed

    Li, Wan-Lu; Li, Yong; Xu, Cong-Qiao; Wang, Xue-Bin; Vorpagel, Erich; Li, Jun

    2015-12-01

    Systematic theoretical and experimental investigations have been performed to understand the periodicity, electronic structures, and bonding of gold halides using tetrahalide [AuX4](-) anions (X = F, Cl, Br, I, At, Uus). The [AuX4](-) (X = Cl, Br, I) anions were experimentally produced in the gas phase, and their negative-ion photoelectron spectra were obtained, exhibiting rich and well-resolved spectral peaks. As expected, Au-X bonds in such series contain generally increasing covalency when halogen ligands become heavier. We calculated the adiabatic electron detachment energies as well as vertical electron detachment energies using density functional theory methods with scalar relativistic and spin-orbit coupling effects. The computationally simulated photoelectron spectra are in good agreement with the experimental ones. Our results show that the trivalent Au(III) oxidation state becomes progressively less stable while Au(I) tends to be preferred when the halides become heavier along the Periodic Table. This series of molecules provides an example for manipulating the oxidation state of metals in complexes through ligand design. PMID:26550845

  14. C-S barrier and vibrational analyses of (halocarbonyl)sulfenyl halides XCO-SX (X = F, Cl, and Br).

    PubMed

    Badawi, Hassan M

    2004-09-01

    The structural stability of (halocarbonyl)sulfenyl halides XCO-SX (X is F, Cl, and Br) was investigated by DFT-B3LYP and ab initio MP2 calculations using 6-311 + G(**) basis set. From the calculations the molecules were found to exist predominantly in the trans conformation (two halogen atoms are trans to each other). Full energy optimizations were carried out for the minima and the transition states (TS) at the two levels, from which the rotational barriers about C-S bond in the three molecules were calculated to be about 12-13 kcal mol(-1). The vibrational frequencies of (fluorocarbonyl)sulfenyl fluoride (FCO-SF), (chlorocarbonyl)-sulfenyl chloride (ClCO-SCl), and (bromocarbonyl)-sulfenyl bromide (BrCO-SBr) were computed at the DFT-B3LYP level and the vibrational assignments for the normal modes of the stable forms of the compounds were made on the basis of normal coordinate calculations and experimental data of the chloride.

  15. 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.

  16. 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.

  17. Nonceramic Preparation Techniques for Ternary Halides AB2X4 with A = Mg, Mn, Zn; B = Li, Na; X = Cl, Br

    NASA Astrophysics Data System (ADS)

    Solinas, I.; Lutz, H. D.

    1995-06-01

    Two alternative techniques for synthesizing ternary halides AB2X4 were studied and compared to the classical "ceramic" method. Tribochemical reaction of LiCl with ZnCl2 has been proved to be an easy method for synthesizing the stable spinel-type room-temperature modification of Li2ZnCl4 as well as olivine-type Na2ZnCl4 and Na2ZnBr4. Reaction times and activation energies decrease in the order Li2ZnCl4 > Na2ZnCl4 > Na2ZnBr4. On the other hand, MgCl2 and MnCl2 do not react mechanochemically with LiCl and NaCl at all. In addition, it is possible to synthesize ternary halides as Li2MnCl4 and Li2ZnCl4 by dehydration of appropriate hydrates. The modification of Li2ZuCl4 obtained by this method depends on the dehydration conditions.

  18. 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].

  19. Bromine enrichment in the near-surface region of Br-doped NaCl single crystals diagnosed by Rutherford backscattering spectrometry.

    PubMed

    Hess, M; Krieger, U K; Marcolli, C; Huthwelker, T; Ammann, M; Lanford, W A; Peter, Th

    2007-05-24

    Bromine released from sea-salt aerosols and seawater ice is known for its high chemical reactivity. Previous studies have suggested that its availability to the gas-phase could be enhanced by segregation processes increasing Br concentration on the aerosol surface as compared to the bulk. However, little is known about the composition within the near-surface region, that is, the outermost approximately 100 monolayers. We used Rutherford backscattering spectrometry (RBS) to measure Br concentration profiles to a depth of about 750 nm of Br-doped NaCl single crystals to characterize the thermodynamics and kinetics of Br segregation to the near-surface region in moist air. These experiments were carried out on cleavage planes of melt-grown and of annealed solution-grown crystals at room temperature and relative humidities (RH) too low for formation of a stable liquid phase. Segregation of Br was below the detection limit on melt-grown crystals with Br/Cl = 0.01. In the case of annealed solution-grown crystals with Br/Cl = 0.002, average segregations of (0.24 +/- 0.11) x 10(15) and (0.42 +/- 0.12) x 10(15) Br atoms cm-2 were observed at 50% and 65% RH, respectively. No segregation was found at 20% RH. The observed Br segregation can be explained by the formation of an adsorbed liquid layer (depending on crystal surface properties and relative humidity) and preferential, diffusion-limited dissolution of Br into this layer according to the partition coefficient of Br between aqueous and solid NaCl. The thickness of the adsorbed liquid layer, which depends on crystal surface geometry and on relative humidity, can be estimated to range from 4 to at most 59 nm on the basis of measured Br concentrations and partition coefficients. Applying this concept of partitioning to natural sea salt suggests a Br/Cl molar ratio of up to 0.2 in adsorbed surface water of crystallized natural aerosol particles compared to about 0.0015 in seawater. This would have a major impact on

  20. Sunlight-driven Ag-AgCl(1-x)Br(x) photocatalysts: enhanced catalytic performances via continuous bandgap-tuning and morphology selection.

    PubMed

    Zhu, Mingshan; Chen, Chuncheng; Chen, Penglei; Lei, Bin; Ma, Wanhong; Liu, Minghua

    2013-08-14

    The solid solution (SS) method is an effective way to design impactful photocatalysts, owing to its merit of continuous bandgap-tuning. A calcination, usually breaking the morphology of a material, has to be used to synthesize such catalysts, although the morphology is a critical issue affecting its catalytic behavior. It thus is strongly desired to construct SS-based catalysts with a shaped morphology. Here, we report that AgCl(1-x)Br(x) SS-based photocatalysts, Ag-AgCl(1-x)Br(x), with a shaped morphology, can be produced via an ion-exchange between nanostructured Ag-AgCl and KBr. It is found that when sphere-like Ag-AgCl is employed as a precursor, the Ag-AgCl(1-x)Br(x), maintains its morphology when x is in the range of 0-1. The bandgap, and the catalytic activities of these Ag-AgCl(1-x)Br(x) for the degradation of methyl orange, display a monotonic narrowing and a continuous enhancement, respectively, with the increase of x. In contrast, when cube-like Ag-AgCl is used as a precursor, the Ag-AgCl(1-x)Br(x) preserves its morphological features when x ≤ 0.5, while a morphology distortion is observed when x ≥ 0.75. Fascinatingly, although the bandgap of thus-constructed Ag-AgCl(1-x)Br(x) also exhibits a monotonic narrowing with the increase of x, they (x ≠ 0, 1) display enhanced catalytic activity compared with the two terminal materials, Ag-AgCl and Ag-AgBr, wherein Ag-AgCl0.5Br0.5, with a cube-like morphology, shows the highest catalytic performance. The synergistic effect of morphology selection and bandgap narrowing plays an important role for these intriguing new findings. Our work provides a unique forum for an optimized selection of SS-based photocatalysts in terms of morphology selection and bandgap-tuning.

  1. New constraints on the release of noble gases during in vacuo crushing and application to scapolite Br-Cl-I and 40Ar/ 39Ar age determinations

    NASA Astrophysics Data System (ADS)

    Kendrick, M. A.; Phillips, D.

    2009-10-01

    The release of irradiation-produced noble gas isotopes ( 38Ar Cl, 80Kr Br, 128Xe I and 39Ar K) during in vacuo crushing scapolite has been investigated and is compared to quartz. Three thousand crushing strokes released ˜98% of fluid inclusion-hosted noble gas from quartz. In comparison, 3000 crushing strokes released only ˜4% of the lattice-hosted 38Ar Cl from a scapolite gem. In vacuo crushing released lattice Ar preferentially relative to lattice Kr or Xe and prolonged crushing released ˜88% of the lattice-hosted noble gas in 96,000 crushing strokes. We suggest fast diffusion pathways generated by crushing are an important noble gas release mechanism and we demonstrate two applications of prolonged in vacuo crushing on irradiated scapolite. Firstly, scapolite molar Br/Cl and I/Cl values are shown to vary over a similar range as crustal fluids. The Cl-rich scapolite gem from Hunza, Pakistan has Br/Cl of 0.5-0.6 × 10 -3 and I/Cl values of 0.3-2 × 10 -6, that are similar to fluids that have dissolved evaporites. In contrast, three out of four skarn-related scapolites from the Canadian Grenville Province have molar Br/Cl values of 1.5-2.4 × 10 -3, and I/Cl values of 11-24 × 10 -6, that are broadly consistent with skarn formation by magmatic fluids. The fourth Grenvillian scapolite, with only 0.02 wt% Cl, has an exceptionally elevated molar Br/Cl value of up to ˜54 × 10 -3 and I/Cl of 284 × 10 -6. It is unclear if these values reflect the composition of fluids formed during metamorphism or preferential incorporation of Br and I in Cl-poor meionitic scapolite. Secondly, the Grenvillian scapolites give plateau ages of between 830 Ma and 400 Ma. The oldest ages post-date regional skarn formation by ˜200 Myr, but are similar to feldspar cooling ages in the Province. The age variation in these samples is attributed to a combination of factors including variable thermal history and the presence of mineral sub-grains in some of the samples. These sub

  2. 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.

  3. Threshold energies for the reactions Oh- + Ch3X yields Ch30H + X- (X = Cl, Br) measured by tandem mass spectrometry: Deprotonation energies (acidities) of Ch3Cl and Ch3Br. (Reannouncement with new availability information)

    SciTech Connect

    Hierl, P.M.; Henchman, M.J.; Paulson, J.F.

    1992-12-31

    In a tandem mass spectrometer, a beam of OH{sup {minus}} ions was reacted with methyl chloride and methyl bromide at collision energies in the range 0.2 < ET < 5 eV. For both of the methyl halides, excitation functions, sigma (ET), were measured for the two competing channels, endoergic proton transfer and exoergic nucleophilic displacement: OH{sup {minus}} + CH3X yields H20 + CH2X yields CH3OH + X{sup {minus}}. The threshold energies estimated for the proton transfer reactions are used to derive energies of deprotonation for CH3Cl and CH3Br of 1672 + or - 10 and 1660 + or - lO kJmol{sup {minus}1} respectively.

  4. 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.

  5. 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.

  6. 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

  7. 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. PMID:27411163

  8. A High Resolution Phoswich Detector: LaBr{sub 3}(Ce) Coupled With LaCl{sub 3}(Ce)

    SciTech Connect

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

    2010-04-26

    An innovative solution for the forward end-cap CALIFA calorimeter of R{sup 3}B is under investigation consisting of two scintillation crystals, LaBr{sub 3} and LaCl{sub 3}, 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 DELTAE1+DELTAE2 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 MicroAnalisis de Materiales (CMAM) in Madrid. Good resolution and time signal separation have been achieved.

  9. 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. PMID:27603224

  10. 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.

  11. Low-energy electron attachment to C 6F 5X (X=F, Cl, Br and I)

    NASA Astrophysics Data System (ADS)

    Shimamori, Hiroshi; Sunagawa, Takeyoshi; Ogawa, Yuji; Tatsumi, Yoshitsugu

    1994-09-01

    Rate constants have been measured for electron attachment to C 6F 5X (X=F, Cl, Br and I) in Xe buffer gas at room temperature at the mean electron energy between 0.04 and 2 eV using the pulse-radiolysis microwave-cavity method combined with microwave heating. The cross sections as a function of electron energy have been derived by unfolding the obtained rate constants. The rate constants at thermal energy are all the same, around 2 × 10 -7 cm 3 molecule -1 s -1, for C 6F 5X, and decrease monotonically with increasing mean energy. The cross sections have a peak at ≈0 eV for each compound. Only C 6F 6 shows another cross-section maximum at ≈0.75 eV. The discrepancy in the rate constants at thermal energy with those in previous reports is discussed.

  12. Dipole-bound states of the alkali-superhalogen anions: LiBeX3- (X = F, Cl, Br)

    NASA Astrophysics Data System (ADS)

    Tong, Jing; Li, Ying; Wu, Di; Cui, Song-Hua; Li, Zhi-Ru; Huang, Xu-Ri

    2010-08-01

    The dipole-bound states of the LiBeX3- (X = F, Cl, Br) anions were predicted at the MP2/aug-cc-pVDZ+5 s5 p level of theory. Upon electron attachment, the neutral LiBeX 3 host shows noteworthy geometrical relaxation, which is accompanied by a significant increase of the dipole moment. The LiBeX3- anions exhibit large vertical electron detachment energies of 539.2-886.5 MeV at the CCSD(T)/aug-cc-pVDZ+6 s6 p4 d level, indicating that the binding of electrons to the alkali-superhalogen LiBeX 3 molecules is feasible. In addition, the stabilities of the LiBeX3- anions with respect to the neutral hosts, are found to be closely related to the electronegativity of the X ligands and partial atomic charge localized on Be.

  13. Surprising quenching of the spin-orbit interaction significantly diminishes H2O···X [X = F, Cl, Br, I] dissociation energies.

    PubMed

    Czakó, Gábor; Császár, Attila G; Schaefer, Henry F

    2014-12-26

    The H2O···X complexes, with X = F, Cl, Br, and I, show considerable viability with nonspin-orbit De(D0) dissociation energy values of 3.73(2.42), 3.60(2.68), 3.54(2.72), and 3.36(2.77) kcal mol(-1) for X = F, Cl, Br, and I, respectively, obtained at the CCSD(T)-F12b/aug-cc-pVTZ(-PP) level of theory using relativistic pseudopotentials (PPs) for Br and I. Spin-orbit (SO) corrections, computed with the Breit-Pauli operator in the interacting states approach at the all-electron MRCI+Q/aug-cc-pwCVTZ(-PP) level, are found to depend sensitively and unpredictably on the O···X separations. 96% (F), 87% (Cl), 54% (Br), and 30% (I) quenching of the SO corrections significantly reduces the dissociation energies of the H2O···X complexes, resulting in De(D0) values of 3.38(2.06), 2.86(1.94), 1.64(0.83), and 1.23(0.64) kcal mol(-1) for X = F, Cl, Br, and I, respectively.

  14. 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).

  15. Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China.

    PubMed

    Li, Junxia; Wang, Yanxin; Xie, Xianjun

    2016-02-15

    In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000-10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ(37)Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility.

  16. Cl/Br ratios and chlorine isotope evidences for groundwater salinization and its impact on groundwater arsenic, fluoride and iodine enrichment in the Datong basin, China.

    PubMed

    Li, Junxia; Wang, Yanxin; Xie, Xianjun

    2016-02-15

    In order to identify the salinization processes and its impact on arsenic, fluoride and iodine enrichment in groundwater, hydrogeochemical and environmental isotope studies have been conducted on groundwater from the Datong basin, China. The total dissolved solid (TDS) concentrations in groundwater ranged from 451 to 8250 mg/L, and 41% of all samples were identified as moderately saline groundwater with TDS of 3000-10,000 mg/L. The results of groundwater Cl concentrations, Cl/Br molar ratio and Cl isotope composition suggest that three processes including water-rock interaction, surface saline soil flushing, and evapotranspiration result in the groundwater salinization in the study area. The relatively higher Cl/Br molar ratio in groundwater from multiple screening wells indicates the contribution of halite dissolution from saline soil flushed by vertical infiltration to the groundwater salinization. However, the results of groundwater Cl/Br molar ratio model indicate that the effect of saline soil flushing practice is limited to account for the observed salinity variation in groundwater. The plots of groundwater Cl vs. Cl/Br molar ratio, and Cl vs δ(37)Cl perform the dominant effects of evapotranspiration on groundwater salinization. Inverse geochemical modeling results show that evapotranspiration may cause approximately 66% loss of shallow groundwater to account for the observed hydrochemical pattern. Due to the redox condition fluctuation induced by irrigation activities and evapotranspiration, groundwater salinization processes have negative effects on groundwater arsenic enrichment. For groundwater iodine and fluoride enrichment, evapotranspiration partly accounts for their elevation in slightly saline water. However, too strong evapotranspiration would restrict groundwater fluoride concentration due to the limitation of fluorite solubility. PMID:26657361

  17. Temperature-induced structural changes in CaCl{sub 2},CaBr{sub 2}, and CrCl{sub 2}: A synchrotron x-ray powder diffraction study

    SciTech Connect

    Howard, Christopher J.; Kennedy, Brendan J.; Curfs, Caroline

    2005-12-01

    The halides CaCl{sub 2},CaBr{sub 2}, and CrCl{sub 2} all adopt, at room temperature, the same distorted rutile structure, in orthorhombic space group Pnnm, known as the calcium chloride structure. Upon heating, CaCl{sub 2} and CaBr{sub 2} each undergoes a continuous transformation to the true tetragonal rutile structure, in space group P4{sub 2}/mnm, the transition temperatures being 235 and 553 deg. C, respectively. By contrast, the structural change in CrCl{sub 2} upon heating is just further elongation of octahedra already lengthened by Jahn-Teller effects, and no phase transition occurs. The orthorhombic structure is maintained by a strong and temperature-dependent geometrical coupling of the orthorhombic strain to the order parameter, represented by the tilt angle of the CrCl{sub 6} octahedron.

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

    NASA Astrophysics Data System (ADS)

    Souda, Ryutaro

    2007-12-01

    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 135-140K, 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 160K. The infrared absorption band revealed that the aqueous lithium-halide solutions and crystals are formed simultaneously at 160K; 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. 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

  20. 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

  1. 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

  2. A DFT study of the extractive desulfurization mechanism by [BMIM](+)[AlCl4](-) ionic liquid.

    PubMed

    Li, Hongping; Chang, Yonghui; Zhu, Wenshuai; Jiang, Wei; Zhang, Ming; Xia, Jiexiang; Yin, Sheng; Li, Huaming

    2015-05-14

    In this work, the interaction nature between [BMIM](+)[AlCl4](-) ionic liquid (IL) and aromatic sulfur compounds (thiophene, benzothiophene, and dibenzothiophene) has been studied by means of density functional theory (M06-2X functional) combined with an implicit solvation model. Although [BMIM](+)[AlCl4](-) is a metal-containing IL, its extractive desulfurization mechanism is different from other metal-containing ILs but similar to non-metal-containing ILs. Important reactions involved in extractive desulfurization (EDS) were systematically studied. Our results have demonstrated that both the cation and the anion play important roles in EDS. On the basis of the structure analysis, reduced density gradient analaysis (RDG), and energy decomposition analysis, [BMIM](+) cation affords a π-π interaction while [AlCl4](-) anion provides a hydrogen bonding interaction. Electrostatic potential analysis implies the dominant π-π interaction and hydrogen bonding interaction are driven by electrostatic interaction between IL and aromatic sulfur compounds. Interaction energy between [BMIM](+)[AlCl4](-) and thiophene (TH), benzothiophene (BT), and dibenzothiophene (DBT) follows the order TH < BT < DBT. Moreover, Al-containing IL with a high molar ratio of AlCl3 ([BMIMCl]/2[AlCl3]) has also been studied. Results show that [Al2Cl7](-) species will be formed with excess AlCl3. However, the [Al2Cl7](-)-based IL cannot improve the EDS performance. Improvement of EDS performance with a high molar ratio of AlCl3 is credited to the Lewis acidity of AlCl3. Charge analysis reveals that there is no obvious charge transfer during the reaction, which is different from Fe-containing ILs as well as solid sorbents. In addition, CH-π interaction is not important for the current system.

  3. Systematics of BX3 and BX2(+) Complexes (X = F, Cl, Br, I) with Neutral Diphosphine and Diarsine Ligands.

    PubMed

    Burt, Jennifer; Emsley, James W; Levason, William; Reid, Gillian; Tinkler, Iain S

    2016-09-01

    The coordination chemistry of the neutral diphosphines, R2P(CH2)2PR2 (R = Me or Et) and o-C6H4(PR'2)2 (R' = Me or Ph), and the diarsine, o-C6H4(AsMe2)2, toward the Lewis acidic BX3 (X = F, Cl, Br, and I) fragments is reported, including several rare complexes incorporating BF3 and BF2(+). The studies have revealed that the flexible dimethylene linked diphosphines form [(BX3)2{μ-R2P(CH2)2PR2}] exclusively, confirmed by multinuclear NMR ((1)H, (11)B, (19)F{(1)H}, and (31)P{(1)H}) and IR spectroscopy and microanalytical data. Crystallographic determinations of the four BX3 complexes with Et2P(CH2)2PEt2 confirm the 2:1 stoichiometry and, taken together with the spectroscopic data, reveal that the Lewis acid behavior of the BX3 fragment toward phosphine ligands increases in the order F ≪ ClBr < I. The first diphosphine- and diarsine-coordinated dihaloboronium cations, [BX2{o-C6H4(EMe2)2}](+) (E = P, As), are obtained using the rigid, preorganized o-phenylene linkages. These complexes are characterized similarly, and the data indicate that the complexes with o-C6H4(AsMe2)2 are much more labile and readily decomposed than the phosphine analogues. X-ray crystallographic studies on [BX2{o-C6H4(PMe2)2}][BX4] (X = Cl, Br), [BI2{o-C6H4(PMe2)2}][I3], and [BCl2{o-C6H4(AsMe2)2}][BCl4] confirm the presence of distorted tetrahedral coordination at boron through a chelating diphosphine or diarsine and two X ligands, with d(B-P) revealing a similar increase in Lewis acidity down group 17. Comparison of d(B-P) and d(B-As) reveals an increase of ca. 0.08 Å from P to As. Reaction of BCl3 with the diphosphine dioxide Ph2P(O)CH2P(O)Ph2 gives the ligand-bridged dimer [(BCl3)2{Ph2P(O)CH2P(O)Ph2}], while using either BF3 gas or [BF3(SMe2)] gives a mixture containing both [(BF3)2{μ-Ph2P(O)CH2P(O)Ph2}] and the unexpected difluoroboronium salt, [BF2{Ph2P(O)CH2P(O)Ph2}][B2F7] containing a chelating phosphine oxide. The structure of the latter was confirmed crystallographically.

  4. Systematics of BX3 and BX2(+) Complexes (X = F, Cl, Br, I) with Neutral Diphosphine and Diarsine Ligands.

    PubMed

    Burt, Jennifer; Emsley, James W; Levason, William; Reid, Gillian; Tinkler, Iain S

    2016-09-01

    The coordination chemistry of the neutral diphosphines, R2P(CH2)2PR2 (R = Me or Et) and o-C6H4(PR'2)2 (R' = Me or Ph), and the diarsine, o-C6H4(AsMe2)2, toward the Lewis acidic BX3 (X = F, Cl, Br, and I) fragments is reported, including several rare complexes incorporating BF3 and BF2(+). The studies have revealed that the flexible dimethylene linked diphosphines form [(BX3)2{μ-R2P(CH2)2PR2}] exclusively, confirmed by multinuclear NMR ((1)H, (11)B, (19)F{(1)H}, and (31)P{(1)H}) and IR spectroscopy and microanalytical data. Crystallographic determinations of the four BX3 complexes with Et2P(CH2)2PEt2 confirm the 2:1 stoichiometry and, taken together with the spectroscopic data, reveal that the Lewis acid behavior of the BX3 fragment toward phosphine ligands increases in the order F ≪ ClBr < I. The first diphosphine- and diarsine-coordinated dihaloboronium cations, [BX2{o-C6H4(EMe2)2}](+) (E = P, As), are obtained using the rigid, preorganized o-phenylene linkages. These complexes are characterized similarly, and the data indicate that the complexes with o-C6H4(AsMe2)2 are much more labile and readily decomposed than the phosphine analogues. X-ray crystallographic studies on [BX2{o-C6H4(PMe2)2}][BX4] (X = Cl, Br), [BI2{o-C6H4(PMe2)2}][I3], and [BCl2{o-C6H4(AsMe2)2}][BCl4] confirm the presence of distorted tetrahedral coordination at boron through a chelating diphosphine or diarsine and two X ligands, with d(B-P) revealing a similar increase in Lewis acidity down group 17. Comparison of d(B-P) and d(B-As) reveals an increase of ca. 0.08 Å from P to As. Reaction of BCl3 with the diphosphine dioxide Ph2P(O)CH2P(O)Ph2 gives the ligand-bridged dimer [(BCl3)2{Ph2P(O)CH2P(O)Ph2}], while using either BF3 gas or [BF3(SMe2)] gives a mixture containing both [(BF3)2{μ-Ph2P(O)CH2P(O)Ph2}] and the unexpected difluoroboronium salt, [BF2{Ph2P(O)CH2P(O)Ph2}][B2F7] containing a chelating phosphine oxide. The structure of the latter was confirmed crystallographically. PMID

  5. 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…

  6. Bridgman growth of LaBr 3:Ce and LaCl 3:Ce crystals for high-resolution gamma-ray spectrometers

    NASA Astrophysics Data System (ADS)

    Higgins, W. M.; Glodo, J.; Van Loef, E.; Klugerman, M.; Gupta, T.; Cirignano, L.; Wong, P.; Shah, K. S.

    2006-01-01

    Single crystals of LaBr 3:Ce and LaCl 3:Ce have been grown by the vertical Bridgman technique. Crystals of these scintillators are used in the fabrication of high-resolution, gamma-ray spectrometers. The LaBr 3:Ce and LaCl 3:Ce crystals we have grown have high light outputs of ˜80,000 and 50,000 photons/MeV, respectively, and fast principal decay constants of <30 ns. The emission wavelength for the LaBr 3:Ce and LaCl 3:Ce scintillators are λ=360 and 350 nm, respectively. Both materials have excellent energy resolutions of ˜3% FWHM for 662 keV photons at room temperature. In this paper, we will report on our results to date for vertical Bridgman crystal growth and characterization of Ce-doped LaBr 3 and LaCl 3 crystals. We will also describe the handling and processing procedures developed for these oxygen and moisture sensitive materials.

  7. Mass-Dependent and -Independent Fractionation of Mercury Isotope during Gas-Phase Oxidation of Elemental Mercury Vapor by Atomic Cl and Br.

    PubMed

    Sun, Guangyi; Sommar, Jonas; Feng, Xinbin; Lin, Che-Jen; Ge, Maofa; Wang, Weigang; Yin, Runsheng; Fu, Xuewu; Shang, Lihai

    2016-09-01

    This study presents the first measurement of Hg stable isotope fractionation during gas-phase oxidation of Hg(0) vapor by halogen atoms (Cl(•), Br(•)) in the laboratory at 750 ± 1 Torr and 298 ± 3 K. Using a relative rate technique, the rate coefficients for Hg(0)+Cl(•) and Hg(0)+Br(•) reactions are determined to be (1.8 ± 0.5) × 10(-11) and (1.6 ± 0.8) × 10(-12) cm(3) molecule(-1) s(-1), respectively. Results show that heavier isotopes are preferentially enriched in the remaining Hg(0) during Cl(•) initiated oxidation, whereas being enriched in the product during oxidation by Br(•). The fractionation factors for (202)Hg/(198)Hg during the Cl(•) and Br(•) initiated oxidations are α(202/198) = 0.99941 ± 0.00006 (2σ) and 1.00074 ± 0.00014 (2σ), respectively. A Δ(199)Hg/Δ(201)Hg ratio of 1.64 ± 0.30 (2σ) during oxidation of Hg(0) by Br atoms suggests that Hg-MIF is introduced by the nuclear volume effect (NVE). In contrast, the Hg(0) + Cl(•) reaction produces a Δ(199)Hg/Δ(201)Hg-slope of 1.89 ± 0.18 (2σ), which in addition to a high degree of odd-mass-number isotope MIF suggests impacts from MIF effects other than NVE. This reaction also exhibits significant MIF of (200)Hg (Δ(200)Hg, up to -0.17‰ in the reactant) and is the first physicochemical process identified to trigger (200)Hg anomalies that are frequently detected in atmospheric samples. PMID:27501307

  8. 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.

  9. On the oxidation of the three-dimensional aromatics [B(12)X(12)](2-) (X=F, Cl, Br, I).

    PubMed

    Boeré, René T; Derendorf, Janis; Jenne, Carsten; Kacprzak, Sylwia; Kessler, Mathias; Riebau, Rainer; Riedel, Sebastian; Roemmele, Tracey L; Rühle, Monika; Scherer, Harald; Vent-Schmidt, Thomas; Warneke, Jonas; Weber, Stefan

    2014-04-01

    The perhalogenated closo-dodecaborate dianions [B12 X12 ](2-) (X=H, F, Cl, Br, I) are three-dimensional counterparts to the two-dimensional aromatics C6 X6 (X=H, F, Cl, Br, I). Whereas oxidation of the parent compounds [B12 H12 ](2-) and benzene does not lead to isolable radicals, the perhalogenated analogues can be oxidized by chemical or electrochemical methods to give stable radicals. The chemical oxidation of the closo-dodecaborate dianions [B12 X12 ](2-) with the strong oxidizer AsF5 in liquid sulfur dioxide (lSO2 ) yielded the corresponding radical anions [B12 X12 ](⋅-) (X=F, Cl, Br). The presence of radical ions was proven by EPR and UV/Vis spectroscopy and supported by quantum chemical calculations. Use of an excess amount of the oxidizing agent allowed the synthesis of the neutral perhalogenated hypercloso-boranes B12 X12 (X=Cl, Br). These compounds were characterized by single-crystal X-ray diffraction of dark blue B12 Cl12 and [Na(SO2 )6 ][B12 Br12 ]⋅B12 Br12 . Sublimation of the crude reaction products that contained B12 X12 (X=Cl, Br) resulted in pure dark blue B12 Cl12 or decomposition to red B9 Br9 , respectively. The energetics of the oxidation processes in the gas phase were calculated by DFT methods at the PBE0/def2-TZVPP level of theory. They revealed the trend of increasing ionization potentials of the [B12 X12 ](2-) dianions by going from fluorine to bromine as halogen substituent. The oxidation of all [B12 X12 ](2-) dianions was also studied in the gas phase by mass spectrometry in an ion trap. The electrochemical oxidation of the closo-dodecaborate dianions [B12 X12 ](2-) (X=F, Cl, Br, I) by cyclic and Osteryoung square-wave voltammetry in liquid sulfur dioxide or acetonitrile showed very good agreement with quantum chemical calculations in the gas phase. For [B12 X12 ](2-) (X=F, Cl, Br) the first and second oxidation processes are detected. Whereas the first process is quasi-reversible (with oxidation potentials in the range between +1

  10. 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.

  11. Competition between hydrogen abstraction and halogen displacement in the reaction of Br with CH3I, CH3Br, and CH3Cl.

    PubMed

    Irikura, Karl K; Francisco, Joseph S

    2007-07-26

    Sudden ozone depletion events in the marine boundary layer are associated with jumps in the CH3Br mixing ratio, but current models of atmospheric chemistry explain neither the ozone depletion nor the CH3Br spikes. We have used ab initio theory to predict the forward and reverse rate constants for the competing hydrogen abstraction and homolytic substitution (SH2) channels of the title reactions. Including the spin-orbit stabilization of the transition structures increases the rate constants by factors between 1.3 and 49. For the atmospherically relevant case of CH3I, our findings suggest that the hydrogen abstraction and homolytic substitution reactions are competitive. The predicted branching fraction to CH3Br is about 13%.

  12. Neutron diffraction study of the antiferromagnetic oxyhalides Sr 3Fe 2O 5Cl 2, Sr 3Fe 2O 5Br 2 and Sr 3FeCoO 5Cl 2

    NASA Astrophysics Data System (ADS)

    Knee, Christopher S.; Field, Marianne A. L.; Weller, Mark T.

    2004-05-01

    The crystal and magnetic structures of the Ruddlesden-Popper related iron oxyhalides, Sr 3Fe 2O 5X 2, X=Cl and Br and the mixed B site material Sr 3FeCoO 5Cl 2 have been studied using neutron powder diffraction. The materials consist of double layers of Fe(Co)O 5 square pyramids separated along the z-direction by SrX rocksalt layers. Neutron powder diffraction data were collected at room temperature and 2 K for Sr 3Fe 2O 5Br 2 and Sr 3FeCoO 5Cl 2, whilst the thermal dependence of both the nuclear structure and the long range magnetic order of Sr 3Fe 2O 5Cl 2 in the range 17 K< T<625 K has been studied, allowing the materials T N éel =590 K to be determined. All three phases adopt G-type antiferromagnetic spin structures, with the moments confined within the xy-plane. The materials possess low temperature moments μ=4.40(4) μB, μ=4.07(6) μB and μ=2.11(4) μB for Sr 3Fe 2O 5Cl 2, Sr 3Fe 2O 5Br 2 and Sr 3FeCoO 5Cl 2, respectively, indicating the presence of high spin iron (III) in all compounds.

  13. In Situ Detection of OH, HO2, ClO, BrO, NO2, ClONO2, BrONO2, ClOOCl, H2O, and O3 from the ER2

    NASA Technical Reports Server (NTRS)

    Anderson, James G.

    2001-01-01

    We review here the scientific progress that has emerged during the period January 1, 1998 through March 31, 2001. Results from the Sage III Ozone Loss and Validation Experiment (SOLVE) and Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission, and continuing work on prior missions, taken in order, including radical control of ozone on the northern hemisphere stratosphere, evolution of NO2 over the arctic winter and its effects on reactive chlorine, and the first measurements of ClOOCl in the stratosphere.

  14. Vibrational spectra, isolated CH stretching frequencies and CH bond lengths in CH 3OCH 2X compounds (XF, Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    McKean, D. C.; Torto, I.; Morrisson, A. R.

    1983-05-01

    Infrared and Raman spectra are reported for CH 3OCH 2X, CHD 2OCD 2X, CD 3OCHDX (XF, Cl, Br, I) and for CH 3OCD 2Cl and CD 3OCH 2Cl, in various phases. νCHis values are obtained which enable CH bond lengths and dissociation energies to be predicted. The changes in bond lengths from Me 2O to MeOCH 2X and from MeOCH 2F to MeOCH 2Cl are in good agreement with those calculated ab initio and in radical disagreement with microwave-based values. The effect of halogen is to strengthen all the CH bonds present, especially that lying parallel to the CX one. All major features in the spectra are explained if only the gauche skeletal conformer exists in the phases studied. However, two transient bands in solid films of CH 3OCH 2F may indicate the presence of a metastable trans conformer phase. Secure assignments for CH 3OCH 2Cl are based on the CH 3OCD 2Cl and CD 3OCH 2Cl spectra and extended by analogy to most of the vibrations of the F, Br and I compounds.

  15. 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. PMID:26889515

  16. Theoretical insight into the interaction between SnX2 (X = H, F, Cl, Br, I) and benzene.

    PubMed

    Matczak, Piotr

    2016-09-01

    For a series of five model complexes composed of a singlet SnX2 molecule (X = H, F, Cl, Br, I) and a benzene molecule, the first-principles calculations of their energetics and the analysis of their electron density topology have been performed. The CCSD(T)/CBS interaction energy between SnX2 and C6H6 fall into the range between -10.0 and -11.2 kcal/mol, which indicates that the complexes are rather weakly bound. The relevant role of electrostatic and dispersion contributions to the interaction energy between SnX2 and C6H6 is highlighted in the results obtained from the symmetry-adapted perturbation theory (SAPT). The electron density topological analysis has been carried out using the quantum theory of atoms in molecules (QTAIM) and the noncovalent interactions (NCI) visualization index. Both QTAIM and NCI prove the closed-shell, noncovalent and attractive character of the interaction. A very small charge transfer from C6H6 to SnX2 has been detected. The formation of the five complexes is accompanied by the electron density deformations that are spatially restricted mostly to the region around the Sn atom and its adjacent C atom. The results presented in this work shed some light on the nature of the interactions associated with crystalline structural motifs involving low-valent tin complexed with neutral aryl rings. PMID:27525639

  17. 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.

  18. 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.

  19. a Computational Investigation of c-C3H2...HX(X = F, Cl, Br) H-Bonded Complexes

    NASA Astrophysics Data System (ADS)

    Varadwaj, Pradeep R.; Varadwaj, Arpita; Peslherbe, Gilles H.

    2011-06-01

    Cyclopropenylidene (c-C3H2) is of significant importance in interstellar chemistry and synthetic chemistry (e.g., transition metal and organic catalysis). Because of its peculiar structure, c-C3H2 can act as a hydrogen-bond donor or acceptor. In order to gain insight into this feature, the ground-state potential energy surfaces of singlet c-C3H2 complexed with hydrogen halides HX (X = F, Cl, Br) have been explored extensively by density-functional theory (B3LYP) and {ab initio} quantum chemistry (MP2) with a variety of basis sets, cc-pVxZ and aug-cc-pVxZ (x = D, T). The complexes characterized have the carbenic end of c-C3H2 H-bonded to HX, with some proton transfer occurring, the extent of which follows the order HF < HCl < HBr. Accompanying the complex formation are the dipole moment enhancement, the charge transfer, red shifts of the HX vibrational stretching frequencies together with the significant enhancement of band intensity and concomitant HX bond elongation. The nature of H-bonding in these complexes has been explored, based on energy decomposition schemes and the Bader's quantum theory of atoms-in-molecules, with the conclusion that c-C3H2 is a strong H-bond acceptor with respect to the hydrogen halides.

  20. 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.

  1. 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. PMID:27146283

  2. 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.

  3. 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.

  4. Exceedingly Facile Ph—X Activation (X=Cl, Br, I) with Ruthenium(II): Arresting Kinetics, Autocatalysis, and Mechanisms†

    PubMed Central

    Miloserdov, Fedor M.; McKay, David; Muñoz, Bianca K.; Samouei, Hamidreza

    2015-01-01

    Abstract [(Ph3P)3Ru(L)(H)2] (where L=H2 (1) in the presence of styrene, Ph3P (3), and N2 (4)) cleave the Ph—X bond (X=Cl, Br, I) at RT to give [(Ph3P)3RuH(X)] (2) and PhH. A combined experimental and DFT study points to [(Ph3P)3Ru(H)2] as the reactive species generated upon spontaneous loss of L from 3 and 4. The reaction of 3 with excess PhI displays striking kinetics which initially appears zeroth order in Ru. However mechanistic studies reveal that this is due to autocatalysis comprising two factors: 1) complex 2, originating from the initial PhI activation with 3, is roughly as reactive toward PhI as 3 itself; and 2) the Ph—I bond cleavage with the just‐produced 2 gives rise to [(Ph3P)2RuI2], which quickly comproportionates with the still‐present 3 to recover 2. Both the initial and onward activation reactions involve PPh3 dissociation, PhI coordination to Ru through I, rearrangement to a η2‐PhI intermediate, and Ph—I oxidative addition. PMID:26036691

  5. Volatiles in a peralkaline system: Abiogenic hydrocarbons and F Cl Br systematics in the naujaite of the Ilímaussaq intrusion, South Greenland

    NASA Astrophysics Data System (ADS)

    Krumrei, Thomas V.; Pernicka, Ernst; Kaliwoda, Melanie; Markl, Gregor

    2007-05-01

    Agpaitic rocks comprise most of the exposed part of the 1.16 Ga old, 8 × 17 km large and about 1700 m thick Ilímaussaq intrusion in South Greenland. Within these, more than 600 m thick sequence of sodalite-rich "naujaites" (mainly sodalite + arfvedsonite + alkali feldspar + nepheline + eudialyte + aenigmatite) are interpreted as a sodalite flotation cumulate. Sodalites show two to three different zones in cathodoluminescence (CL) and at least two zones in thin sections. The CL zones can be related to chemical differences detectable by electron microprobe, whereas relations with optical zonations are less obvious. Compositional trends in sodalite reflect trends in the evolution of volatile contents in the melt. The sodalite at Ilímaussaq is almost free of Ca and closely corresponds to the pure Na-Cl sodalite endmember with about 7 wt.% of Cl; S contents reach up to 0.9 wt.%. Cl/Br ratios range from 500 to 1700. Raman spectroscopy shows that S is present as [SO 4] 2- in sodalite, although sphalerite (ZnS) is a stable phase in naujaites. Peralkalinity and fO 2 conditions allow S 2- and [SO 4] 2- to be present contemporaneously. The whole naujaite sequence is divided into two parts, an upper part with low, homogeneous S contents and Cl/Br ratios in the sodalite cores, and a lower part with strongly variable and higher S contents and with Cl/Br ratios, which are decreasing downwards. The details of the S content and the Cl/Br ratio evolution show that sodalite strongly influences the halogen contents of the melt by scavenging Cl and Br. The naujaites were formed from a highly reduced, halogen-rich magma in equilibrium with magmatic methane at about 800 °C, which, upon ascent, cooling and fractionation, exsolved an aqueous fluid phase. Both fluids were trapped in separate inclusions indicating their immiscibility. Micrometer-sized aegirine crystals and primary hydrocarbon-bearing inclusions are abundant in the crystal cores. The inclusions were trapped at pressures

  6. The aluminum electrode in AlCl3-alkali-halide melts

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.; Giner, J.

    1972-01-01

    Passivation phenomena were observed upon cathodic and anodic polarization of the Al electrode in AlCl3-KCl-NaCl melts between 100 and 160 C. They are caused by formation of a solid salt layer at the electrode surface resulting from concentration changes upon current flow. The anodic limiting currents increased with temperature and with decreasing AlCl3 content of the melt. Current voltage curves obtained on a rotating aluminum disk showed a linear relationship between the anodic limiting current and 1/sq root of 2 pi (rps). Upon cathodic polarization dentrite formation occurs at the Al electrode. The activation overvoltage in AlCl3-KCl-NaCl (57.5-12.5-20 mol%) was determined by galvanostatic current step methods. An apparent exchange current density of 270 mA/cm2 at 130 C and a double layer capacity of 40 plus or minus 10 microfarad/cm2 were measured.

  7. 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

  8. 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. PMID:26207728

  9. 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. PMID:26401599

  10. 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.

  11. The halogen (F, Cl, Br, I) and H2O systematics of Samoan lavas: Assimilated-seawater, EM2 and high-3He/4He components

    NASA Astrophysics Data System (ADS)

    Kendrick, Mark A.; Jackson, Matthew G.; Hauri, Erik H.; Phillips, David

    2015-01-01

    The Samoan mantle plume samples two or more mantle components including an extreme EM2 composition with 87Sr/86Sr > 0.720 and a primitive component with high 3He/4He. The high 87Sr/86Sr melts have a unique potential to constrain the composition of the EM2 mantle end-member that is commonly attributed to subduction recycling. However, a previous study of H2O, CO2, S, F and Cl in Samoan glasses was hampered by the presence of unresolved assimilated sea water. The current study builds on the earlier work by extending the volatile database to include the trace halogens Br and I, and reporting new volatile data for additional glasses with 87Sr/86Sr up to 0.7125 and 3He/4He up to 15 Ra (Ra is the atmospheric 3He/4He ratio of 1.39 ×10-6). The selected glasses with MgO of 4.0 to 6.5 wt.% have CO2 concentrations of 4 to 200 ppm that reflect degassing of CO2 on the seafloor. The glasses contain 0.7-1.9 wt.% H2O, 880-1870 ppm F, 490-1790 ppm Cl, 1.9-7.2 ppm Br, 19-130 ppb I and 0.6-1.7 wt.% K. Correlations between the concentrations of these elements suggest the melts retain H2O concentrations close to pre-degassing values and demonstrate the melts have been variably affected by assimilation of seawater-derived brines. The brines are indicated to have had salinities of 55 ± 15 wt.% salt, F/Cl ratios close to seawater (e.g. <0.0001), Br/Cl ratios ∼ 40% higher than seawater, and I/Cl ratios ten times the seawater value. It is calculated the melts assimilated brine fractions of 0 to 0.45 wt.%, which contributed up to ∼30% of the total H2O and up to ∼70% of the total Cl in the melts. After accounting for the effects of brine assimilation, the Samoan melts are suggested to have a fairly constant magmatic Cl/K of 0.05 ± 0.2, which is lower than the median MORB value. Assimilation-corrected H2O/Ce values are not correlated with 87Sr/86Sr, but the sample with the highest 87Sr/86Sr of 0.7125 has an assimilation-corrected H2O/Ce of 83 ± 3, that is significantly lower than

  12. 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.

  13. Kinetic studies of the BrO + ClO cross-reaction over the range T = 246-314 K.

    PubMed

    Ferracci, Valerio; Rowley, David M

    2014-01-21

    The kinetics of the atmospherically important gas phase radical reaction between BrO and ClO have been studied over the temperature range T = 246-314 K by means of laser flash photolysis coupled with UV absorption spectroscopy. Charge-coupled-device (CCD) detection allowed simultaneous monitoring of both free radicals and the OClO product using 'differential' spectroscopy, which minimised interference from underlying UV absorbing species. In this way, the total rate coefficient for BrO + ClO → products (1) was measured, along with that for the OClO producing channel of this process BrO + ClO → OClO + Br (1c). These reaction rate coefficients are described by the Arrhenius expressions: k1/cm(3) molecule(-1) s(-1) = (2.5 ± 2.2) × 10(-12) exp[(630 ± 240)/T] and k(1c)/cm(3) molecule(-1) s(-1) = (4.6 ± 3.0) × 10(-12) exp[(280 ± 180)/T], where errors are 2σ, statistical only. An extensive sensitivity analysis was performed to quantify the potential additional systematic uncertainties in this work arising from uncertainties in secondary chemistry, absorption cross-sections and precursor concentrations. This analysis identified the reactions of initial and secondarily generated bromine atoms (specifically Br + O3 and Br + Cl2O) as particularly important, along with the reversible combination of ClO with OClO forming Cl2O3. Potential uncertainty in this latter process was used to define the lowest temperature of the present study. Results from this work indicate larger absolute values for k1 and k(1c) than those reported in previous studies, but a weaker negative temperature dependence for k(1c) than previously observed, resulting in a branching ratio for with a positive temperature dependence, in disagreement with previous studies. is the principal source of OClO in the polar stratosphere and is commonly used in atmospheric models as an indicator of stratospheric bromine chemistry. Thus these measurements might lead to a reinterpretation of modelled

  14. 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.

  15. 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. PMID:27332751

  16. 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

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

    NASA Astrophysics Data System (ADS)

    Zilker, Zeev; Daykhovsky, Leon; Nageris, Ben I.; Feinmesser, R.; Papaioannou, Thanassis; Ravid, Avi; Kariv, Naam; Katzir, Abraham

    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.

  18. Measurements of solid-liquid equilibria in the ternary system NaCl-NaBr-H2O at 373 K

    NASA Astrophysics Data System (ADS)

    Sang, Shihua; Hu, Yongxia; Cui, Ruizhi; Hu, Juanxin; Wang, Yuan

    2015-07-01

    Solid-liquid equilibria in the ternary system NaCl-NaBr-H2O at 373 K were measured by the isothermal dissolution equilibrium method. The solubilities of salts and densities of saturated solutions in the ternary system were determined experimentally. The equilibrium solid phases were also determined by chemical analysis and X-ray powder diffraction. Using the experimental data, the phase diagram of the ternary system was obtained, which comprise one univariant curve and one stationary phase in crystallization filed of Na (Cl, Br). The ternary system was solid solution type. Density values in the equilibrium solution increase with an increase of the sodium bromide concentration while decrease with an increase of the sodium chloride concentration. The relationship equation of equilibrium liquid phase and the solid phase composition data were fitted with a regression equation.

  19. 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.

  20. 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.

  1. The Role of Spin-Orbit Coupling in the Double-Ionization Photoelectron Spectra of XCN(2+) (X = Cl, Br, and I).

    PubMed

    Manna, Soumitra; Mishra, Sabyashachi

    2016-03-10

    The photoelectron spectra of XCN(2+) (X = Cl, Br, and I) were calculated employing ab initio electronic structure methods with high-level electron correlation and explicit treatment of spin-orbit coupling. Twelve scalar-relativistic excited states of the dicationic systems, calculated from state-averaged CASSCF/MRCI calculations, were used as the electronic basis to evaluate spin-orbit eigenstates. While the spin-orbit effects in ClCN(2+) are found to be negligible, the electronic spectroscopy of BrCN(2+) and ICN(2+) is significantly influenced by interstate spin-orbit coupling. Several electronic degeneracies are lifted, and many unexpected accidental degeneracies occurred due to the spin-orbit coupling. In particular, the spin-orbit interactions between X̃ (3)Σ(-)-b̃ (1)Σ(+), Ã (3)Π-c̃ (1)Π, B̃ (3)Δ-ã (1)Δ, and C̃ (3)Σ(+)-d̃ (1)Σ(-) are found to be strong in BrCN(2+) and ICN(2+). By careful analysis of the effect of spin-orbit coupling parameters and the spin-orbit eigenstate composition, an assignment of the hitherto unidentified experimental photoelectron bands of BrCN(2+) and ICN(2+) is presented.

  2. Recognition of a novel type X═N-Hal···Hal (X = C, S, P; Hal = F, Cl, Br, I) halogen bonding.

    PubMed

    Gushchin, Pavel V; Kuznetsov, Maxim L; Haukka, Matti; Kukushkin, Vadim Yu

    2013-04-01

    The chlorination of the eight-membered platinum(II) chelates [PtCl2{NH═C(NR2)N(Ph)C(═NH)N(Ph)C(NR2)═NH}] (R = Me (1); R2 = (CH2)5 (2)) with uncomplexed imino group with Cl2 gives complexes bearing the ═N-Cl moiety [PtCl4{NH═C(NR2)N(Ph)C(═NCl)N(Ph)C(NR2)═NH}] (R = Me (3); R2 = (CH2)5 (4)). X-ray study for 3 revealed a novel type intermolecular halogen bonding ═N-Cl···Cl(-), formed between the Cl atom of the chlorinated imine and the chloride bound to the platinum(IV) center. The processing relevant structural data retrieved from the Cambridge Structural Database (CSDB) shows that this type of halogen bonding is realized in 18 more molecular species having X═N-Hal moieties (X = C, P, S, V, W; Hal = Cl, Br, I), but this weak ═N-Hal···Hal(-) bonding was totally neglected in the previous works. The presence of the halogen bonding in 3 was confirmed by theoretical calculations at the density functional theory (DFT, M06-2X) level, and its nature was analyzed. PMID:23469756

  3. Syntheses, crystal structures, and optical properties of Pb{sub 6}B{sub 3}O{sub 10}X (X=F, Cl, Br)

    SciTech Connect

    Dong, Lingyun; Pan, Shilie; Wu, Hongping; Su, Xin; Yu, Hongwei; Wang, Ying; Chen, Zhaohui; Huang, Zhenjun; Yang, Zhihua

    2013-08-15

    A series of lead-containing halogen oxyborates, Pb{sub 6}B{sub 3}O{sub 10}X (X=F, Cl, Br), have been grown by high-temperature solution method and their crystal structures were determined by single-crystal X-ray diffraction. They are isostructural and crystallize in the space group Pbcm of the orthorhombic crystal system. The crystal structures are dominated by one-dimensional {sub ∞}[(Pb{sub 4}O)(BO{sub 3}){sub 3}] “Zig-Zag”-chains, while the remaining Pb atoms and X (X=F, Cl, Br) atoms are filled to balance the charge. Compared with the previously reported compound Pb{sub 4}O(BO{sub 3}){sub 2} (the molecular formula Pb{sub 4}O(BO{sub 3}){sub 2} can be regarded as Pb{sub 6}B{sub 3}O{sub 10.5}) with the space group Aba2, the structures of Pb{sub 6}B{sub 3}O{sub 10}X (X=F, Cl, Br) are completely different from that of Pb{sub 4}O(BO{sub 3}){sub 2}. IR spectroscopy, UV–vis-NIR diffuse reflectance spectroscopy, thermal analysis, and theoretical calculations were also performed on the reported materials. Highlights: • A new family of lead-containing halogen oxyborates, Pb{sub 6}B{sub 3}O{sub 10}X (X=F, Cl, Br), have been grown by high-temperature solution method. • Owing to the introduction of X atoms into Pb{sub 4}O(BO{sub 3}){sub 2}, the structures of Pb{sub 6}B{sub 3}O{sub 10}X are completely different. • The crystal structures are dominated by one-dimensional {sub ∞}[(Pb{sub 4}O)(BO{sub 3}){sub 3}] “Zig-Zag”-chains.

  4. Determination of the atomic geometries of the (110) surfaces of CuCl and CuBr by dynamical low-energy electron diffraction intensity analysis

    NASA Astrophysics Data System (ADS)

    Duke, C. B.; Paton, A.; Lazarides, A.; Kahn, A.

    1996-11-01

    The atomic geometries of the nonpolar (110) surfaces of CuCl and CuBr are determined by dynamical analysis of the intensities of 13 diffracted beams for CuCl and 16 beams for CuBr associated with normally incident electrons at T=125 and 100 K, respectively. The structural model is specified by six independent variables consisting of the tilt angles (ωi) of the top two layers, the three independent bond lengths (ci-aj) associated with atoms in the top two layers, and the inner potential. The focus of our analysis is the accuracy and precision with which these six structural parameters can be extracted from the measured intensities. A six-dimensional statistical error analysis was performed for two electron-solid scattering models: one model in which all nonstructural parameters assumed the values used in a family of previous structural analyses for the (110) surface of CuCl and other binary zinc-blende structure materials, and one in which these parameters were treated as adjustable parameters to fit the measured intensities. The structural parameters emanating from these two analyses differ by Δω<=4° and Δ(ci-aj)<=0.3 Å. Statistical analysis of uncertainties in the structural parameters resulting only from uncertainties in the measured intensities yields Δω<=1.3°, Δ(ci-aj)<=0.02 Å. Thus, the uncertainties in the structural parameters associated with the selection of the nonstructural parameters, especially the model of the electron exchange interaction, dominate those associated with the uncertainties in the experimental intensity data. Within these uncertainties we find the top-layer bond lengths are contracted by 0.3 Å for CuCl(110) and 0.1 Å or less for CuBr(110). Changes in the backbonds from the anion and cation cannot be established for CuCl using the existing intensity data in our analysis. For CuBr(110) the backbond from the top-layer cation is contracted by 0.35+/-0.2 Å. The tilt angles are ω1=(53+/-2)° for CuCl and (35+/-2)° for CuBr with

  5. Computationally efficient methodology to calculate C-H and C-X (X = F, Cl, and Br) bond dissociation energies in haloalkanes

    SciTech Connect

    McGivern, W.S.; Derecskei-Kovacs, A.; North, S.W.; Francisco, J.S.

    2000-01-20

    A computationally efficient method for calculating C-H and C-X (X = F, Cl, and Br) bond dissociation energies in haloalkanes has been developed by determining correction factors to MP2/cc-pVtz energies. Corrections for basis set effects were determined by the difference in bond dissociation energies calculated at the MP2/cc-pVtz and MP2/cc-pV5z levels, and correlation effects were corrected by calculating the difference in energies at the MP2/cc-pVtz and CCSD(T)/cc-pVtz levels. Subsequent corrections for the spin-orbit energy of the atomic fragment and zero-point energy were applied to give a final bond dissociation energy. The correction factors were determined using CH{sub 4}, CH{sub 3}F, CH{sub 3}Cl, and CH{sub 3}Br and are found to yield bond dissociation energies in excellent agreement with experimental results. This correction may also be broadly applied to multihalogen compounds, as shown in calculations of the C-H and C-X bond dissociation energies of CH{sub 2}X{sub 2} and CHX{sub 3} (X = F, Cl, and Br) compounds, which accurately reproduce experimental values.

  6. 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.

  7. On the electrochemical formation of Pu-Al alloys in molten LiCl-KCl

    NASA Astrophysics Data System (ADS)

    Mendes, E.; Malmbeck, R.; Nourry, C.; Souček, P.; Glatz, J.-P.

    2012-01-01

    Properties of Pu-Al alloys were investigated in connection with development of pyrochemical methods for reprocessing of spent nuclear fuel. Electroseparation techniques in molten LiCl-KCl are being developed in ITU to group-selectively recover actinides from the mixture with fission products. In the process, actinides are electrochemically reduced on solid aluminium cathodes, forming solid actinide-aluminium alloys. This article is focused on electro-chemical characterisation of Pu-Al alloys in molten LiCl-KCl, on electrodeposition of Pu on solid Al electrodes and on determination of chemical composition and structure of the formed alloys. Cyclic voltammetry and chronopotentiometry were used to study Pu-Al alloys in the temperature range 400-550 °C. Pu is reduced to metal in one reduction step Pu 3+/Pu 0 on an inert W electrode. On a reactive Al electrode, the reduction of Pu 3+ to Pu 0 occurs at a more positive potential due to formation of Pu-Al alloys. The open circuit potential technique was used to identify the alloys formed. Stable deposits were obtained by potentiostatic electrolyses of LiCl-KCl-PuCl 3 melts on Al plates. XRD and SEM-EDX analyses were used to characterise the alloys, which were composed mainly of PuAl 4 with some PuAl 3. In addition, the preparation of PuCl 3 containing salt by carbochlorination of PuO 2 is described.

  8. 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.

  9. 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. PMID:27155987

  10. Investigating the optical properties of polycrystalline AgCl(1-x)Br(x) (0≤x≤1) and Ag(0.95)Tl(0.05)Br(0.95)I(0.05) for IR engineering.

    PubMed

    Korsakov, Alexandr S; Vrublevsky, Dmitry S; Korsakov, Victor S; Zhukova, Liya V

    2015-09-10

    Using the Michelson technique we measured the refractive indices for the plane-parallel thin plates made of AgCl1-xBrx(0≤x≤1) and, to the best of our knowledge, for the first time for the Ag0.95Tl0.05Br0.95I0.05 plate, manufactured by hot embossing, at 632.8 nm. We recorded their absorption spectra within the range of 0.19-41.67 μm using UV-Vis spectrophotometry and Fourier transform infrared spectroscopy, which demonstrated that the increase of substituent silver bromide or thallium monoiodide mole fraction in the corresponding solid solution causes the optical density to grow. As the result it moves the transmission edges toward longer wavelengths, while slightly reducing the transmission peak. PMID:26368977

  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. Ab initio molecular orbital study of XO{sub 2}{sup +} (X = F, Cl, Br, I) systems

    SciTech Connect

    Alcami, M.; Mo, O.; Yanez, M.; Cooper, I.L.

    1999-04-15

    The depletion of stratospheric ozone has resulted in an increasing interest in the study of the possible reaction mechanisms responsible for its depletion. The structures and relative stabilities of the cationic forms of the halogen dioxides have been studied by means of ab initio molecular orbital calculations. For fluorine- and chlorine-containing compounds the geometries and the harmonic vibrational frequencies of all possible isomers were calculated at the QCISD/6-311+G(2d) level of theory. For bromine- and iodine-containing compounds the effective core-potential basis sets of Hay and Wadt, modified to include a set of diffuse functions and two sets of polarization functions, were employed. For all systems the final energies were obtained at the QCISD(T)/6-311+G(3df) level of theory. In addition, multiconfiguration-based methods have also been used. The relative stabilities of structures XOO{sup +} and OXO{sup +} are greatly reduced relative to those observed for the corresponding neutral species. In fact, for Cl and I derivatives, the lowest energy isomer corresponds to the symmetric OXO{sup +} open-chain species. The corresponding cyclic structures arise as local minima on the respective potential energy surfaces, but they lie much higher in energy than the OXO{sup +} open-chain form or the XOO{sup +} isomer. There are significant differences in bonding between XOO{sup +} and OXO{sup +}, the X-O interaction in OXO{sup +} being more covalent than in XOO{sup +}. There are also trends along the series that reflect the pronounced disparity between the electron affinity of F{sup +} and those of the heavier atoms of the group. FOO{sup +} species can be viewed as F({sup 2}P)-O{sub 2}{sup +} complexes, whereas XOO{sup +}(X = Br, I) species can be regarded as X{sup +}({sup 3}P)-O{sub 2} complexes. The OXO{sup +} open-chain species have an electron charge distribution similar to that of the ozone molecule, reflecting the same number of valence electrons in each case.

  13. 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.

  14. 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. PMID:27437566

  15. 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.

  16. A coordinatively flexible hexadentate ligand gives structurally isomeric complexes M2(L)X3 (M = Cu, Zn; X = Br, Cl).

    PubMed

    Wegeberg, Christina; McKee, Vickie; McKenzie, Christine J

    2016-01-01

    Polypyridyl multidentate ligands based on ethylenediamine backbones are important metal-binding agents with applications in biomimetics and homogeneous catalysis. The seemingly hexadentate tpena ligand [systematic name: N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetate] reacts with zinc chloride and zinc bromide to form trichlorido[μ-N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetato]dizinc(II), [Zn2(C22H24N5O2)Cl3], and tribromido[μ-N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetato]dizinc(II), [Zn2Br3(C22H24N5O2)]. One Zn(II) ion shows the anticipated N5O coordination in an irregular six-coordinate site and is linked by an anti carboxylate bridge to a tetrahedral ZnX3 (X = Cl or Br) unit. In contrast, the Cu(II) ions in aquatribromido[μ-N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetato]dicopper(II)-tribromido[μ-N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetato]dicopper(II)-water (1/1/6.5) [Cu2Br3(C22H24N5O2)][Cu2Br3(C22H24N5O2)(H2O)]·6.5H2O, occupy two tpena-chelated sites, one a trigonal bipyramidal N3Cl2 site and the other a square-planar N2OCl site. In all three cases, electrospray ionization mass spectra were dominated by a misleading ion assignable to [M(tpena)](+) (M = Zn(2+) and Cu(2+)). PMID:26742830

  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. Germylenes: structures, electron affinities, and singlet-triplet gaps of the conventional XGeCY(3) (X = H, F, Cl, Br, and I; Y = F and Cl) species and the unexpected cyclic XGeCY(3) (Y = Br and I) systems.

    PubMed

    Bundhun, Ashwini; Abdallah, Hassan H; Ramasami, Ponnadurai; Schaefer, Henry F

    2010-12-23

    A systematic investigation of the X-Ge-CY(3) (X = H, F, Cl, Br, and I; Y = F, Cl, Br, and I) species is carried out using density functional theory. The basis sets used for all atoms (except iodine) in this work are of double-ζ plus polarization quality with additional s- and p-type diffuse functions, and denoted DZP++. Vibrational frequency analyses are performed to evaluate zero-point energy corrections and to determine the nature of the stationary points located. Predicted are four different forms of neutral-anion separations: adiabatic electron affinity (EA(ad)), zero-point vibrational energy corrected EA(ad(ZPVE)), vertical electron affinity (EA(vert)), and vertical detachment energy (VDE). The electronegativity (χ) reactivity descriptor for the halogens (X = F, Cl, Br, and I) is used as a tool to assess the interrelated properties of these germylenes. The topological position of the halogen atom bound to the divalent germanium center is well correlated with the trend in the electron affinities and singlet-triplet gaps. For the expected XGeCY(3) structures (X = H, F, Cl, Br, and I; Y = F and Cl), the predicted trend in the electron affinities is well correlated with simpler germylene derivatives (J. Phys. Chem. A 2009, 113, 8080). The predicted EA(ad(ZPVE)) values with the BHLYP functional range from 1.66 eV (FGeCCl(3)) to 2.20 eV (IGeCF(3)), while the singlet-triplet splittings range from 1.28 eV (HGeCF(3)) to 2.22 eV (FGeCCl(3)). The XGeCY(3) (Y = Br and I) species are most often characterized by three-membered cyclic systems involving the divalent germanium atom, the carbon atom, and a halogen atom.

  19. Substitution Reactions of the Aluminum Chlorogermylenoid H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3.

    PubMed

    Yan, Bingfei; Zhang, Mingxia; Li, Wenzuo; Xiao, Cuiping; Li, Qingzhong; Cheng, Jianbo

    2016-01-01

    Quantum chemical calculations have been performed for the substitution reactions of the aluminum chlorogermylenoid H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3 to get more insights into the reactivity of H2GeClAlCl2. The theoretical calculated results indicated that the substitution reactions of H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3 proceeded in a concerted manner. There were one transition state and one intermediate which connected the reactants and the products along the potential energy surface. The six substitution reactions of H2GeClAlCl2 with HF, H2O, NH3, HCl, H2S, and PH3 are compared with the addition reaction s of H2Ge with these hydrides. And based on the calculated results we concluded that the substitution reactions of H2GeClAlCl2 with these hydrides involve two steps, one is dissociation onto H2Ge with AlCl3, and the other is the addition reactions of H2Ge with HF, H2O, NH3, HCl, H2S, and PH3.

  20. Oxygen and hydrogen isotope fractionation by hydration complexes of Li +, Na +, K +, Mg 2+, F -, Cl -, and Br -: a theoretical study

    NASA Astrophysics Data System (ADS)

    Driesner, T.; Ha, T.-K.; Seward, T. M.

    2000-09-01

    Hydration complexes of the ions Li +, Na +, Mg 2+, F -, Cl -, and Br - that are expected to occur in natural brines, hydrothermal solutions, or volcanic vapors were studied theoretically using quantum mechanical methods, in particular density functional theory. The normal modes of vibration were calculated for minimum energy configurations obtained with the BLYP and B3LYP functionals in combination with the 6-31G∗∗ and 6-311G∗∗ basis sets. Enthalpies of dissociation for Li +, Na +, and Cl - hydrates calculated from these vibrational spectra are in good agreement with experimental values. From the theoretical normal modes of vibration, the reduced partition function ratios for D/H and 18O/ 16O substitution in the hydration complexes as well as the isotope fractionation between the complexes and monomeric water vapor were calculated. Following a scheme introduced by Bopp et al. (1974) we used the gas-phase results to model isotope salt effects in aqueous solutions. Good agreement with measured results was obtained for both oxygen and hydrogen isotope effects caused by cations, whereas anion results are less satisfactory, probably due to first shell-second shell interactions, which are not properly accounted for by the calculations. However, the calculations for the gas-phase cation hydration complexes can be utilized to gain insight into the nature of isotope "salt effects" in aqueous electrolyte solutions. Hydration-related "salt effects" are quantitatively dominated by the changes of O-H stretching frequencies due to the presence of the ions. Lower frequencies such as those related to the ion-water bonds are of minor importance. The distance up to which measurable effects on the O-H frequencies (and hence on the reduced partition function ratios) are induced is shown to be limited to the first hydration shell. These results may also be relevant for a better theoretical understanding of isotope fractionation involving clay minerals, adsorption of water on

  1. "XA6" octahedra influencing the arrangement of anionic groups and optical properties in inverse-perovskite [B6O10]XA3 (X = Cl, Br; A = alkali metal).

    PubMed

    Yang, Zhihua; Lei, Bing-Hua; Yang, Bin; Pan, Shilie

    2016-06-01

    Exploring the effect of microscopic units, which set up the perovsikte framework, is of importance for material design. In this study, a series of borate halides with inverse-perovskite structures [B6O10]XA3 (X = Cl, Br; A = alkali metal) have been studied. It was revealed that the distortion and volume of XA6 octahedra influence the arrangement of anionic groups, which leads to the flexibility of the perovskite-related framework and differences in optical properties. Under the structural control scheme, the structure of Rb3B6O10Cl was predicted. The stability of the predicted structure was confirmed by an ab initio density functional theory-based method. The calculation shows Rb3B6O10Cl has a short UV cutoff edge of less than 200 nm, a moderate birefringence and a large second harmonic generation response. PMID:27211304

  2. 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

  3. Second sphere coordination complexes via hydrogen bonding: Synthesis, spectroscopic characterisation of [ trans-Co(en) 2Cl 2]CdX 4 (X=Br or I) and single crystal X-ray structure determination of [ trans-Co(en) 2Cl 2]CdBr 4

    NASA Astrophysics Data System (ADS)

    Sharma, Raj Pal; Sharma, Rajni; Bala, Ritu; Salas, Juan M.; Quiros, Miguel

    2006-08-01

    In an effort to explore [ trans-Co(en) 2Cl 2] + as anion receptor for tetrabromocadmate and tetraiodocadmate ion, green coloured single crystals of [ trans-Co(en) 2Cl 2]CdBr 4I and [ trans-Co(en) 2Cl 2]CdI 4II have been obtained by slowly mixing the separately dissolved trans-dichlorobis(ethylenediamine)cobalt(III) chloride with potassium tetrabromocadmate and tetraiodocadmate in aqueous medium in 2:1 molar ratio. The newly synthesized complex salt was characterized on the basis of elemental analysis and spectroscopic techniques (IR, UV/visible, 1H and 13C NMR). Single crystal X-ray structure determination of [ trans-Co(en) 2Cl 2] 2CdBr 4 revealed that it crystallizes in the orthorhombic space group Pbca with a=18.6201(10), b=12.0872(6), c=24.0877(12) Å, V=5421.3(5) Å 3, Z=8, R=0.0727. Supramolecular hydrogen bonding networks between ionic groups: bromide ions of tetrabromocadmate group and NH groups of coordinated ethylenediamine molecules, i.e. N-H⋯Br - interactions by second sphere coordination besides electrostatic forces of attraction have been observed. This suggests that [ trans-Co(en) 2Cl 2] + is a promising anion receptor for the tetrabromocadmate.

  4. 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.

  5. Influence of irrigation practices on arsenic mobilization: Evidence from isotope composition and Cl/Br ratios in groundwater from Datong Basin, northern China

    NASA Astrophysics Data System (ADS)

    Xie, Xianjun; Wang, Yanxin; Su, Chunli; Li, Junxia; Li, Mengdi

    2012-03-01

    SummaryEnvironment isotopes (δ18O and δ2H) and Cl/Br ratios in groundwater have been used to trace groundwater recharge and geochemical processes for arsenic contamination in Datong Basin. The arsenic concentrations of groundwater samples ranged from 0.4 to 434.9 μg/L with the average of 51.2 μg/L, which exceeded China's drinking water standard (10 μg/L). All the groundwater samples are plotted on or close to the meteoric water line of the δ18O vs. δ2H plot, indicating their meteoric origin. The relationship between δ18O values and Cl/Br ratios and Cl concentrations demonstrate that leaching and mixing are the dominant processes affecting the distribution of high arsenic groundwater in this area. The observed non-linearity in the trend between δ18O and arsenic concentration is due to combined effects of mixing and leaching. The similarity of the trend in Cl/Br ratios and δ18O values for high arsenic groundwater demonstrate that extensive leaching of irrigation return and salt flushing water flow could be the dominant process driving arsenic mobilization in the groundwater system. Moreover, the long term irrigation practice can cause the drastic change of the biogeochemical and redox condition of in the aquifer system, which in turn promotes the mobilization of arsenic. Therefore, groundwater pumping for irrigation in this area of waterborne endemic arsenic poisoning should be under strict control to protect groundwater quality in this area.

  6. 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

    2016-09-01

    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. PMID:27494550

  7. 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

  8. 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.

  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. PMID:25824283

  10. Measurements of the work function of single-walled carbon nanotubes encapsulated by AgI, AgCl, and CuBr using kelvin probe technique with different kinds of probes

    NASA Astrophysics Data System (ADS)

    Zhukov, A. A.; Chernysheva, M. V.; Eliseev, A. A.

    2016-07-01

    We report the results on the measurements of the work function of single-walled carbon nanotubes encapsulated by Agl (AgI@SWCNT), AgCl (AgCl@SWCNT), and CuBr (CuBr@SWCNT) by the local Kelvin probe technique. We found the values of the work function of tubes encapsulated with AgI and AgCl (Φ(AgI@SWCNT) = 5.08 ± 0.02, Φ(AgCl@SWCNT) = 5.10 ± 0.02 eV) to exceed substantially that of pristine carbon nanotubes, and the value of the work function of carbon nanotubes encapsulated with CuBr is Φ(CuBr@SWCNT) = 4.89 ± 0.03 (eV). The measurements are carried out using different kinds of microscope probes including multi-walled carbon nanotube tips.

  11. 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.

  12. Behaviour of I/Br/Cl-THMs and their projected toxicities under simulated cooking conditions: Effects of heating, table salt and residual chlorine.

    PubMed

    Yan, Mingquan; Li, Mingyang; Han, Xuze

    2016-08-15

    This study examined the effects of heating, residual chlorine and concentration of table salt on the generation of iodine-, bromine- and chlorine-containing trihalomethanes (THMs) under simulated cooking conditions. In the case of addition of either KI- or KIO3-fortified salt, total I-THM concentrations increased with increasing iodine concentration, while total Cl/Br-THM concentrations decreased. CHCl2I, CHBrClI, CHBrI2, CHBr2I and CHI3 were formed in the presence of KI salt, while only CHCl2I was formed in the presence of KIO3 salt. CHCl2I was unstable under cooking conditions, and >90% of this DBP was removed during heating, which in some cases increased the concentrations of the other I-THMs. The calculated cytotoxicity increased with addition of KI- or KIO3-fortified salt due to the generation of I-THMs, whose impact on the cytotoxicity at room temperature was equal to or five times higher, respectively, than the cytotoxicity of the simultaneously formed Cl/Br-THMs for the cases of salts. Heating decreased the cytotoxicity, except for the case of addition of KI salt, in which the calculated cytotoxicity of I-THMs increased above 150% as the temperature was increased up to 100°C. The reported results may have important implications for epidemiologic exposure assessments and, ultimately, for public health protection. PMID:27107240

  13. Behaviour of I/Br/Cl-THMs and their projected toxicities under simulated cooking conditions: Effects of heating, table salt and residual chlorine.

    PubMed

    Yan, Mingquan; Li, Mingyang; Han, Xuze

    2016-08-15

    This study examined the effects of heating, residual chlorine and concentration of table salt on the generation of iodine-, bromine- and chlorine-containing trihalomethanes (THMs) under simulated cooking conditions. In the case of addition of either KI- or KIO3-fortified salt, total I-THM concentrations increased with increasing iodine concentration, while total Cl/Br-THM concentrations decreased. CHCl2I, CHBrClI, CHBrI2, CHBr2I and CHI3 were formed in the presence of KI salt, while only CHCl2I was formed in the presence of KIO3 salt. CHCl2I was unstable under cooking conditions, and >90% of this DBP was removed during heating, which in some cases increased the concentrations of the other I-THMs. The calculated cytotoxicity increased with addition of KI- or KIO3-fortified salt due to the generation of I-THMs, whose impact on the cytotoxicity at room temperature was equal to or five times higher, respectively, than the cytotoxicity of the simultaneously formed Cl/Br-THMs for the cases of salts. Heating decreased the cytotoxicity, except for the case of addition of KI salt, in which the calculated cytotoxicity of I-THMs increased above 150% as the temperature was increased up to 100°C. The reported results may have important implications for epidemiologic exposure assessments and, ultimately, for public health protection.

  14. 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.

  15. 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.

  16. 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.

  17. Study of thermodynamic properties of Np-Al alloys in molten LiCl-KCl eutectic

    NASA Astrophysics Data System (ADS)

    Souček, P.; Malmbeck, R.; Mendes, E.; Nourry, C.; Sedmidubský, D.; Glatz, J.-P.

    2009-10-01

    Pyrochemical methods are investigated worldwide within the framework of Partitioning and Transmutation concepts for spent nuclear fuel reprocessing. Electroseparation techniques in a molten LiCl-KCl are being developed in ITU to recover all actinides from a mixture with fission products. During the process, actinides are selectively electrochemically reduced on a solid aluminium cathode, forming solid actinide-aluminium alloys. This work is focused on the thermodynamic properties of Np-Al alloys in a temperature range of 400-550 °C and on the characterisation of the structure and chemical composition of deposits obtained by electrodeposition of Np on solid Al electrodes in a LiCl-KCl-NpCl 3 melt. Cyclic voltammetry and open circuit chronopotentiometry have been used to examine the electrochemical behaviour of Np on inert W and reactive Al electrodes. Gibbs energies, enthalpy and entropy of formation and standard electrode potentials of Np-Al alloys were evaluated and compared with ab initio calculations. Galvanostatic electrolyses at 450 °C were carried out to recover Np onto Al plates and the solid surface deposits were characterised by XRD and SEM-EDX analyses. Stable and dense deposits consisting of NpAl 3 and NpAl 4 alloys were identified. In addition, the conversion of NpO 2 to NpCl 3 is described, using chlorination of the oxide in a molten salt media by pure chlorine gas.

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

    PubMed

    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.

  19. 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.

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

    PubMed

    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

  1. 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.

  2. 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

  3. 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. PMID:27346209

  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. Quantum oscillations in dual-layered quasi-two-dimensional organic metal (ET)4HgBr4(C6H4Cl2)

    NASA Astrophysics Data System (ADS)

    Lyubovskii, R. B.; Pesotskii, S. I.; Shilov, G. V.; Zhilyaeva, E. I.; Flakina, A. M.; Lyubovskaya, R. N.

    2016-08-01

    The behavior of de Haas-van Alfven (dHvA) and Shubnikov-de Haas (ShdH) quantum oscillations in dual-layered quasi-two-dimensional organic metal (ET)4HgBr4(C6H4Cl2) is investigated. The oscillation spectra qualitatively agree with theoretical calculations of the bandgap structure. The angular dependence of the oscillation amplitude of magnetoresistance contains "spin zeros"; the analysis of the location of these zeros allows one to evaluate the electron-phonon interaction constant: λ ≈ 0.2.

  8. UV-VIS Absorption Spectra of Molten AgCl and AgBr and of their Mixtures with Group I and II Halide Salts

    NASA Astrophysics Data System (ADS)

    Greening, Giorgio G. W.

    2015-10-01

    The UV-VIS absorption spectra of (Ag1-X[Li-Cs, Ba]X)Cl and of (Ag1-X[Na, K, Cs]X)Br at 823 K at the concentrations X=0.0, 0.1, 0.2 have been measured. The findings show that on adding the respective halides to molten silver chloride and silver bromide, shifts of the fundamental absorption edge to shorter wavelengths result. A correlation between the observed shifts and the expansion of the silver sub-lattice is found, which is valid for both silver halide systems studied in this work.

  9. 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.

  10. Rate Constants for the Reactions of OH with CH(sub 3)Cl, CH(sub 2) C1(sub 2), CHC1(sub 3)and CH(sub 3)Br

    NASA Technical Reports Server (NTRS)

    Hsu, H-J.; DeMore, W.

    1994-01-01

    Rate constants for the reactions of OH with CH3C1, CH2Cl2, CHCl3 and CH3Br have been measured by a relative rate technique in which the reaction rate of each compound was compared to that of HFC-152a (CH3CHF2)and for CH2Cl2, HFC-161 (CH3CH2F).

  11. 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.

  12. Theoretical study on the substitution reactions of the germylenoid H2GeLiF with SiH3X (X = F, Cl, Br).

    PubMed

    Zhang, Gongxiao; Qi, Yuhua; Xu, Chongjuan

    2016-06-01

    The substitution reactions of H2GeLiF (G) with SiH3X (X = F, Cl, Br) were investigated using calculations performed at the QCISD/6-311++G (d, p)//B3LYP/6-311+G (d, p) level of theory. The results led to the following conclusions. (i) The substitutions are nucleophilic reactions. There are two substitution paths, I and II, which both lead to the germane H2GeFSiH3. The enantiomers of this germane are obtained via these two paths if an H in SiH3X is replaced with a different group or atom. (ii) Both substitution pathways show the same order of barrier heights (SiH3F > SiH3Cl > SiH3Br). The difference between the bond energies of Li-X and Si-X may explain the precedence among the substitution reactions of G with SiH3X. Path I has a lower activation barrier than path II, indicating that path I is more favorable. (iii) Comparison between the relevant insertion and substitution reactions shows that substitutions are more favorable and that the substitution product H2GeFSiH3 predominates over the insertion product. (iv) The substitution reactions of H2GeLiF with SiH3X are exothermic. PMID:27179805

  13. Four-mode quantum calculations of resonance states in complex-forming bimolecular reactions: Cl{sup -}+CH{sub 3}Br

    SciTech Connect

    Schmatz, Stefan

    2005-06-15

    The vibrational resonance states of the complexes formed in the nucleophilic bimolecular substitution (S{sub N}2) reaction Cl{sup -}+CH{sub 3}Br{yields}ClCH{sub 3}+Br{sup -} 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.

  14. 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.

  15. On the structure and physical origin of the interaction in H(2) ... Cl(-) and H(2) ... Br(-) van der Waals anion complexes.

    PubMed

    Lukes, Vladimír; Ilcin, Michal; Laurinc, Viliam; Biskupic, Stanislav

    2004-09-22

    The ab initio three-dimensional potential energy surface (PES) for the weak interaction of hydrogen molecule with bromine anion is presented. The surface was obtained by the supermolecular method at the coupled cluster with single and double excitations and noniterative correction to triple excitations (CCSD(T)) level of theory. Our calculations indicate the van der Waals (vdW) system for the linear orientation at R=3.37 A with a well depth of D(e)=660.1 cm(-1). The presented PES reveals also transition state for the perpendicular orientation at R=4.22 A with a barrier of 607.1 cm(-1). The physical origin of the stability of vdW H(2) ... Br(-) structure with respect to the H(2) ... Cl(-) one was analyzed by the symmetry adapted perturbation theory based on the single determinant Hartree-Fock (HF) wave function. The separation of the interaction energy shows that the dispersion forces play slightly more important role in the stabilization of the vdW system with Br(-) than with Cl(-).

  16. Comparison of π-hole tetrel bonding with σ-hole halogen bonds in complexes of XCN (X = F, Cl, Br, I) and NH3.

    PubMed

    Nziko, Vincent de Paul N; Scheiner, Steve

    2016-02-01

    In addition to the standard halogen bond formed when NH3 approaches XCN (X = F, Cl, Br, I) along its molecular axis, a perpendicular approach is also possible, toward a π-hole that is present above the X-C bond. MP2/aug-cc-pVDZ calculations indicate the latter geometry is favored for X = F, and the σ-hole structure is preferred for the heavier halogens. The π-hole structure is stabilized by charge transfer from the NH3 lone pair into the π*(CN) antibonding orbital, and is characterized by a bond path from the N of NH3 to the C atom of XCN, a form of tetrel bond. The most stable 2 : 1 NH3/XCN heterotrimer for X = F and Cl is cyclic and contains a tetrel bond augmented by a pair of NHN H-bonds. For X = Br and I, the favored trimer is noncyclic, stabilized by a tetrel and a halogen bond.

  17. 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.

  18. 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

  19. Experimental and Chemical Kinetics Study of the Effects of Halon 1211 (CF2BrCl) on the Laminar Flame Speed and Ignition of Light Hydrocarbons.

    PubMed

    Mathieu, Olivier; Keesee, Charles; Gregoire, Claire; Petersen, Eric L

    2015-07-16

    In this study, the effect of Halon 1211 (CF2BrCl) on the ignition delay time and laminar flame speed of CH4, C2H4, and C3H8 were investigated experimentally for the first time. The results showed that the effects of Halon 1211 on the ignition delay time are strongly dependent on the hydrocarbon: the ignition delay time of CH4 is significantly decreased by Halon 1211 addition, while a significant increase in the ignition delay time was observed with C2H4 for the lowest temperatures investigated. Ignition delay times for C3H8 were slightly increased, mostly on the low-temperature side and for the fuel-rich case. A significant reduction in the laminar flame speed was observed for all of the fuels. A tentative chemical kinetics model was assembled from existing models and completed with reactions that have been determined in the literature or estimated when necessary. The experimental results were reproduced satisfactorily by the model, and a chemical analysis showed that most of the effects of Halon 1211 on the ignition delay times of C2H4 and C3H8 are due to the consumption of H radical through the reaction HBr + H ⇄ Br + H2. In the case of methane, the CF2 radical promotes the formation of H via CF2 + CH3 ⇄ CH2:CF2 + H, which then promotes the branching reaction H + O2 ⇄ OH + O. The laminar flame speed results can be explained using catalytic cycles involving Br atoms that are similar to those reported in the literature for CF3Br. This study exhibits the need for a better estimation of the chlorine atom chemistry during the combustion of hydrocarbons in the presence of fire suppressants.

  20. 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.

  1. 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.

  2. 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.

  3. Salts of the 1-cyanocarba-closo-dodecaborate anions [1-NC-closo-1-CB11X11]- (X = H, F, Cl, Br, I).

    PubMed

    Finze, Maik; Sprenger, Jan A P; Schaack, Bernd Bastian

    2010-03-14

    The caesium and tetraethylammonium salts of the 1-cyanocarba-closo-dodecaborate anions [1-NC-closo-1-CB(11)X(11)](-) (X = H, F, Cl, Br, I) were synthesized from CsLi[closo-1-CB(11)X(11)] and phenylcyanate. All anions are stable against aqueous acids and bases, except for the fluorinated anion [1-NC-closo-1-CB(11)F(11)](-) that immediately reacts with water. The Cs(+) and [Et(4)N](+) salts of the anions were characterized by IR, Raman and multinuclear NMR spectroscopy as well as by MALDI and ESI mass spectrometry. The thermal properties of the Cs[1-NC-closo-1-CB(11)X(11)] (X = H, Cl, Br, I) and of some of their tetraethylammonium salts were studied by differential scanning calorimetry. The crystal structures of [Et(4)N][1-NC-closo-1-CB(11)H(11)] and Cs[1-NC-closo-1-CB(11)Cl(11)] were determined and the discussion of the structural and spectroscopic properties is supported by density functional and (RI)-MP2 calculations. A first insight into the hydrolysis of the [1-NC-closo-1-CB(11)F(11)](-) anion is presented and its reactions with water are compared to those of other undecafluorinated carba-closo-dodecaborate anions. The reduced hydrolytic stability of the [1-NC-closo-1-CB(11)F(11)](-) anion in comparison to its homologues is related to differences in the carbon-boron and boron-boron bond lengths of the {closo-1-CB(11)} cage and to different partial charges of the cluster atoms.

  4. A convenient alumination of functionalized aromatics by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl.

    PubMed

    Unsinn, Andreas; Wunderlich, Stefan H; Jana, Anukul; Karaghiosoff, Konstantin; Knochel, Paul

    2013-10-18

    A straightforward and efficient alumination of functionalized arenes by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl (TMP=2,2,6,6-tetramethylpiperidyl) has been developed. In particular, halogenated electron-rich aromatics can be smoothly functionalized by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl. Compared with previously described alumination methods, this procedure avoids extensive cooling and the need for an excess of base. This in situ procedure has proven to be most practical and allows for regio- and chemoselective metalation of a wide range of aromatics with sensitive functional groups (CONEt2 , CO2 Me, CN, OCONMe2 ) or halogens (F, Cl, Br, I). The resulting aromatic aluminates, which were characterized by using NMR spectroscopy, were subjected to allylations, acylations, and palladium-catalyzed cross-coupling reactions after transmetalation to zinc. It was shown that the nature of the Zn salt used for transmetalation is crucial. Thus, compared with ZnCl2 (2 equiv), the use of Zn(OPiv)2 (2 equiv; OPiv=pivalate) allows the subsequent quenching reactions to be performed with only a slight excess of electrophile (1.2 equiv) and provides interesting functionalized aromatics in good yields.

  5. Behavior of BaBr2, BaI2, and BaCl2 at high pressure as analogs to SiO2.

    NASA Astrophysics Data System (ADS)

    Smart, T. J.; Stackhouse, S.; Diamond, M. R.; Godwal, B. K.; Jeanloz, R.

    2015-12-01

    Motivated by the expectation that giant and supergiant planets likely contain rocky components in their cores, we study analogs of the archetypal rock constituent, SiO2. The crystal structures of SiO2 under ultra-high pressures, greater than feasible experimental conditions, are believed to be documented by the high pressure structural sequence of AX2 compounds. Experimental and theoretical work agree on a high pressure transition to the cotunnite (orthorhombic) phase, with first-principles theory predicting that SiO2 transforms to the cotunnite structure at 750 GPa. However, the existence of a postcotunnite (monoclinic) phase as the final high pressure polymorph, suggested by X-ray diffraction (XRD) experiments on ambient pressure cotunnite-structured AX2 compounds (e.g. PbCl2, SnCl2), has been challenged by density-functional theory (DFT) computations. This disagreement could perhaps be due to sensitivity in diamond-anvil cell (DAC) experiments to pressure gradients; conversely, it could perhaps arise from limitations of DFT. This study further explores both the experimental and theoretical sides of this debate, with an aim to resolve this discrepancy. We present synchrotron XRD data on the AX2 compounds BaCl2, BaBr2, and BaI2, compressed up to 70 GPa at room temperature in a DAC. Here we compare our experimentally observed crystallography and equations of state with results from our DFT simulations.

  6. Theoretical study of mixed LiLnX4 (Ln = La, Dy; X = F, Cl, Br, I) rare earth/alkali halide complexes.

    PubMed

    Groen, C P; Oskam, A; Kovács, A

    2000-12-25

    The structure, bonding and vibrational properties of the mixed LiLnX4 (Ln = La, Dy; X = F, Cl, Br, I) rare earth/alkali halide complexes were studied using various quantum chemical methods (HF, MP2 and the Becke3-Lee-Yang-Parr exchange-correlation density functional) in conjunction with polarized triple-zeta valence basis sets and quasi-relativistic effective core potentials for the heavy atoms. Our comparative study indicated the superiority of MP2 theory while the HF and B3-LYP methods as well as less sophisticated basis sets failed for the correct energetic relations. In particular, f polarization functions on Li and X proved to be important for the Li...X interaction in the complexes. From the three characteristic structures of such complexes, possessing 1-(C3v), 2-(C2v), or 3-fold coordination (C3v) between the alkali metal and the bridging halide atoms, the bi- and tridentate forms are located considerably lower on the potential energy surface then the monodentate isomer. Therefore only the bi- and tridentate isomers have chemical relevance. The monodentate isomer is only a high-lying local minimum in the case of X = F. For X = Cl, Br, and I this structure is found to be a second-order saddle point. The bidentate structure was found to be the global minimum for the systems with X = F, Cl, and Br. However, the relative stability with respect to the tridentate structure is very small (1-5 kJ/mol) for the heavier halide derivatives and the relative order is reversed in the case of the iodides. The energy difference between the three structures and the dissociation energy decrease in the row F to I. The ionic bonding in the complexes was characterized by natural charges and a topological analysis of the electron density distribution according to Bader's theorem. Variation of the geometrical and bonding characteristics between the lanthanum and dysprosium complexes reflects the effect of "lanthanide contraction". The calculated vibrational data indicate that

  7. Electrochemical and spectroscopic studies of the chloro and oxochloro complex formation of Nb(V) and Ta(V) in NaCl-AlCl3 melts.

    PubMed

    von Barner, J H; Bjerrum, N J

    2005-12-26

    The equilibrium constant for the chloro complex formation of Nb(V) NbCl6-<--->NbCl5+Cl- (i) in NaCl-AlCl3 melts at 175 degrees C was found to be pKi = 2.86(5). The oxochloro complex formation of Nb(V) and Ta(V) in NaCl-AlCl3 melts at 175 degrees C could be explained by the following equilibria: MOCl4- <-->MOCl3+Cl- (ii) MOCl3<-->MOCl2(+)+Cl- (iii) where M = Nb and Ta. The equilibrium constants determined by potentiometric measurements with chlorine-chloride electrodes were, for M = Nb, pKii = 2.21(4) and pKiii = 3.95(5) and, for M = Ta, pKii = 2.743(15) and pKiii = 4.521(13). NbCl6- has two bands in the UV-vis region, a strong one at 34.7 x 10(3) cm-1 and a weaker one at 41.6 x 10(3) cm-1. The MOCl4- complexes showed in the case of Nb(V) absorption bands at 32.7 and 42.9 x 10(3) cm-1 and in the case of Ta(V) at 38.6 and 48.1 x 10(3) cm-1. PMID:16363855

  8. Visible-light-driven photocatalysts Ag/AgCl dispersed on mesoporous Al2O3 with enhanced photocatalytic performance.

    PubMed

    Feng, Zhouzhou; Yu, Jiajie; Sun, Dongping; Wang, Tianhe

    2016-10-15

    In this paper, Ag/AgCl and Ag/AgCl/Al2O3 photocatalysts were synthesized via a precipitation reaction between NaCl and CH3COOAg or Ag(NH3)2NO3, wherein Ag/AgCl was immobilized into mesoporous Al2O3 medium. The Ag/AgCl-based nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra, and so on. The photocatalysts displayed excellent photocatalytic activity for the degradations of methyl orange (MO) and methylene blue (MB) pollutants under visible light irradiation. The Ag/AgCl(CH3COOAg)/Al2O3 sample exhibited the best photocatalytic performance, degrading 99% MO after 9min of irradiation, which was 1.1 times, 1.22 times and 1.65 times higher than that of Ag/AgCl(Ag(NH3)2NO3)/Al2O3, Ag/AgCl(CH3COOAg) and Ag/AgCl(Ag(NH3)2NO3) photocatalyst, respectively. Meanwhile, Ag/AgCl(CH3COOAg)/Al2O3 also showed excellent capability of MB degradation. Compared to the data reported for Ag/AgCl/TiO2, the Ag/AgCl/Al2O3 prepared in this work exhibited a good performance for the degradation of methyl orange (MO). The results suggest that the dispersion of Ag/AgCl on mesoporous Al2O3 strongly affected their photocatalytic activities. O2(-), OH radicals and Cl(0) atoms are main active species during photocatalysis. PMID:27442145

  9. High temperature infrared vapour spectra, molecular orbital calculations and vibrational analysis of AlCl 3,NH 3 and AlCl 3ND 3

    NASA Astrophysics Data System (ADS)

    Sjøgren, Carl E.; Rytter, E.

    1985-01-01

    The i.r. spectra of Al 3Cl 3NH 3, trichloroammine aluminium, and AlCl 3ND 3, trichloroammine(D) aluminium, vapours were recorded in the 50-1800 and 2300-3500 cm -1 regions with an evacuable Fourier transform spectrometer by transmission and emission techniques. Evacuable cells of nickel, having windows of type lIa diamond and sealed with O-rings of gold, were employed. All i.r. active fundamentals were assigned and a valence force field based upon the present i.r. frequencies was derived. An indirect observation of the inactive torsional mode rules out the possibility of free internal rotation around the AlN bond and this conclusion was supported by an ab initio calculation. The spectra were interpreted in terms of a staggered C 3υ structure and analysis of i.r. band contours and Raman polarization measurements reported in the literature were used as an aid to the assignment of fundamentals.

  10. Theoretical study on cooperative effects between X⋯N and X⋯Carbene halogen bonds (X = F,Cl,Br and I).

    PubMed

    Esrafili, Mehdi D; Mohammdain-Sabet, Fariba; Esmailpour, Parvin

    2013-11-01

    Quantum chemical calculations are performed to study the interplay between halogen⋯nitrogen and halogen⋯carbene interactions in NCX⋯NCX⋯CH2 complexes, where X = F, Cl, Br and I. Molecular geometries and interaction energies of dyads and triads are investigated at the MP2/aug-cc-pVTZ level of theory. It is found that the X⋯N and X⋯Ccarbene interaction energies in the triads are larger than those in the dyads, indicating that both the halogen bonding interactions are enhanced. The estimated values of cooperative energy E coop are all negative with much larger E coop in absolute value for the systems including iodine. The nature of halogen bond interactions of the complexes is analyzed using parameters derived from the quantum theory atoms in molecules methodology and energy decomposition analysis. PMID:24013450

  11. Proton response of CEPA4: A novel LaBr3(Ce)-LaCl3(Ce) phoswich array for high-energy gamma and proton spectroscopy

    NASA Astrophysics Data System (ADS)

    Nácher, E.; Mårtensson, M.; Tengblad, O.; Álvarez-Pol, H.; Bendel, M.; Cortina-Gil, D.; Gernhäuser, R.; Le Bleis, T.; Maj, A.; Nilsson, T.; Perea, A.; Pietras, B.; Ribeiro, G.; Sánchez del Río, J.; Sánchez Rosado, J.; Heinz, A.; Szpak, B.; Winkel, M.; Zieblinski, M.

    2015-01-01

    A new phoswich array, for the detection of high-energy protons and gamma rays from nuclear reactions, has been built. This new detector consists of four individual closely packed scintillator detectors, each of them made of 4 cm of LaBr3(Ce) and 6 cm of LaCl3(Ce) in phoswich configuration (optically coupled and with a common readout). In this paper we report on the results of a beam test performed at the Bronowice Cyclotron Centre (CCB) in Krakow, showing the response of this versatile instrument to high energy protons (70-230 MeV). Furthermore, for the first time we prove that we can reconstruct the original energy of fast protons (E > 200 MeV) which pass through the total length of the crystal while still retaining a good energy resolution.

  12. Conformation and NH stretching of 1,1-dihalogenoheptan-1-amines [CH₃(CH₂)₅CX₂NH₂; X=F, Cl or Br]: halogen and solvent effects.

    PubMed

    Tursun, Mahir; Rhyman, Lydia; Parlak, Cemal; Ramasami, Ponnadurai; Şenyel, Mustafa

    2015-03-15

    The effects of halogen and solvent on the conformation and NH stretching of 1,1-dihalogeno-heptan-1-amines [CH3(CH2)5CX2NH2; X=F, Cl or Br] were investigated using the density functional theory method. The functional used was B3LYP employing the 6-31++G(d,p) basis set for all atoms. Computations were carried out for ten possible conformational isomers of the compounds, in the gas phase and both in a non-polar solvent (benzene) and in a polar solvent (methanol). This research work indicates that both the halogen and the medium affect conformational preference, geometrical parameters and NH vibrational frequency. The findings of this work can be useful to those systems involving changes in the conformations analogous to the compounds studied.

  13. 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.

  14. 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.

  15. Synthesis and structure of the ternary and quaternary strontium nitride halides, Sr{sub 2}N(X, X') (X, X'=Cl, Br, I)

    SciTech Connect

    Bowman, Amy; Smith, Ronald I.; Gregory, Duncan H. . E-mail: Duncan.Gregory@Nottingham.ac.uk

    2006-01-15

    A number of new, layered nitride mixed halides have been synthesised in the quaternary phase systems Sr-N-Cl-Br and Sr-N-Br-I. The variation in structure with composition has been investigated by powder X-ray and powder neutron diffraction techniques and the structure of strontium nitride iodide, Sr{sub 2}NI, has been determined for the first time (rhombohedral space group R-3m, a=4.0103(1)A, c=23.1138(2)A, Z=3). A continuous solid solution exists between Sr{sub 2}NCl and Sr{sub 2}NBr with intermediate compounds adopting the same anti-{alpha}-NaFeO{sub 2} structure (rhombohedral space group R-3m) as the ternary end members. A similar smooth and linear relationship between structure and composition is seen from Sr{sub 2}NBr to Sr{sub 2}NI and hence cubic close packing of metal-nitrogen layers is adopted regardless of halide, X (X'). While nitride and halide anions occupy distinct crystallographic sites, there is no ordering of the halides in the quaternary materials irrespective of stoichiometry or temperature (between 3 and 673K)

  16. Ternary and quaternary layered nitride halides, Ca{sub 2}N(X,X') (X,X'=Cl, Br, I): Evolution of structure with composition

    SciTech Connect

    Bowman, Amy; Smith, Ronald I.; Gregory, Duncan H. . E-mail: Duncan.Gregory@Nottingham.ac.uk

    2005-06-15

    The quaternary systems Ca-N-Cl-Br and Ca-N-Br-I have been investigated resulting in the synthesis of a number of new layered nitride mixed halides. The evolution of structure with composition has been investigated by powder X-ray and powder neutron diffraction techniques. A continuous solid solution exists between Ca{sub 2}NCl and Ca{sub 2}NBr with intermediate compounds adopting the same anti- {alpha}-NaFeO{sub 2} structure (rhombohedral space group R3-bar m) as the ternary end members. A phase transition occurs in the Ca{sub 2}NBr{sub 1-y}I{sub y} system between y=0.7 and y=0.8 corresponding to a switch from cubic close packing to hexagonal close packing of metal-nitrogen layers and corresponding adoption of the anti-{beta}-RbScO{sub 2} (filled anti-CdI{sub 2}) structure (hexagonal space group P6{sub 3}/mmc). While nitride and halide anions occupy distinct crystallographic sites, there is no ordering of halides in quaternary materials irrespective of stoichiometry or structure type. All the nitride halides show temperature independent paramagnetic behaviour between 2 and 300K.

  17. 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

  18. Formation of the Si-B bond: insertion reactions of silylenes into B-X(X = F, Cl, Br, O, and N) bonds.

    PubMed

    Geng, Bing; Xu, Chongjuan; Chen, Zhonghe

    2016-06-01

    The insertion reactions of the silylene H2Si with H2BXHn-1 (X = F, Cl, Br, O, N; n = 1, 1, 1, 2, 3) have been studied by DFT and MP2 methods. The calculations show that the insertions occur in a concerted manner, forming H2Si(BH2)(XHn-1). The essences of H2Si insertions with H2BXHn-1 are the transfers of the σ electrons on the Si atom to the positive BH2 group and the electrons of X into the empty p orbital on the Si atom in H2Si. The order of reactivity in vacuum shows the barrier heights increase for the same-family element X from up to down and the same-row element X from right to left in the periodic table. The energies relating to the B-X bond in H2BXHn-1, and the bond energies of Si-X and Si-B in H2Si(BH2)(XHn-1) may determine the preference of insertions of H2Si into B-X bonds for the same-column element X or for the same-row element X. The insertion reactions in vacuum are similar to those in solvents, acetone, ether, and THF. The barriers in vacuum are lower than those in solvents and the larger polarities of solvents make the insertions more difficult to take place. Both in vacuum and in solvents, the silylene insertions are thermodynamically exothermic. Graphical Abstract The insertion process of H2Si and H2BXHn-1(X = F, Cl, Br, O, and N; n = 1, 1 , 1, 2, 3). PMID:27184004

  19. Insight into the substitution reactions of silylenoid H2SiLiF with GeH3X (X = F, Cl, Br): a theoretical study.

    PubMed

    Yan, Bingfei; Li, Wenzuo; Xiao, Cuiping; Li, Qingzhong; Cheng, Jianbo

    2015-04-01

    The unique substitution reactions of the three-membered-ring silylenoid H2SiLiF with GeH3X (X = F, Cl, Br) were investigated using ab initio and density functional theory calculations. All stationary points on the potential energy surfaces were optimized at the B3LYP/6-311 + G (d, p) level of theory and the QCISD method was then used to calculate the single-point energies. Theoretical calculations predicted that the substitution reactions of H2SiLiF with GeH3X proceed via two reaction paths (I and II), while forming the same product H2FSi-GeH3. In either pathway, there is one precursor complex (Q), one transition state (TS), and one intermediate (IM) connecting the reactants and products. The substitution reaction barriers of H2SiLiF with GeH3X for path I (48.49, 42.71, and 38.71 kJ mol(-1)) decreased with the increase for the same-family element X from up to down in the periodic table, whereas the substitution barriers for path II (6.51, 22.04, and 23.62 kJ mol(-1)) increased with the increase in atomic number of X (X = F, Cl, Br). Path II was more favorable than path I. All the substitution reactions of H2SiLiF with GeH3X were exothermic. The elucidation of the unique mechanism of these substitution reactions suggests a new reaction mode of silicon-germanium bond formation. PMID:25754138

  20. Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX2(pyz)2 (X = Cl, Br, I, NCS; pyz = Pyrazine).

    PubMed

    Liu, Junjie; Goddard, Paul A; Singleton, John; Brambleby, Jamie; Foronda, Francesca; Möller, Johannes S; Kohama, Yoshimitsu; Ghannadzadeh, Saman; Ardavan, Arzhang; Blundell, Stephen J; Lancaster, Tom; Xiao, Fan; Williams, Robert C; Pratt, Francis L; Baker, Peter J; Wierschem, Keola; Lapidus, Saul H; Stone, Kevin H; Stephens, Peter W; Bendix, Jesper; Woods, Toby J; Carreiro, Kimberly E; Tran, Hope E; Villa, Cecelia J; Manson, Jamie L

    2016-04-01

    The crystal structures of NiX2(pyz)2 (X = Cl (1), Br (2), I (3), and NCS (4)) were determined by synchrotron X-ray powder diffraction. All four compounds consist of two-dimensional (2D) square arrays self-assembled from octahedral NiN4X2 units that are bridged by pyz ligands. The 2D layered motifs displayed by 1-4 are relevant to bifluoride-bridged [Ni(HF2)(pyz)2]EF6 (E = P, Sb), which also possess the same 2D layers. In contrast, terminal X ligands occupy axial positions in 1-4 and cause a staggered packing of adjacent layers. Long-range antiferromagnetic (AFM) order occurs below 1.5 (Cl), 1.9 (Br and NCS), and 2.5 K (I) as determined by heat capacity and muon-spin relaxation. The single-ion anisotropy and g factor of 2, 3, and 4 were measured by electron-spin resonance with no evidence for zero-field splitting (ZFS) being observed. The magnetism of 1-4 spans the spectrum from quasi-two-dimensional (2D) to three-dimensional (3D) antiferromagnetism. Nearly identical results and thermodynamic features were obtained for 2 and 4 as shown by pulsed-field magnetization, magnetic susceptibility, as well as their Néel temperatures. Magnetization curves for 2 and 4 calculated by quantum Monte Carlo simulation also show excellent agreement with the pulsed-field data. Compound 3 is characterized as a 3D AFM with the interlayer interaction (J⊥) being slightly stronger than the intralayer interaction along Ni-pyz-Ni segments (J(pyz)) within the two-dimensional [Ni(pyz)2](2+) square planes. Regardless of X, J(pyz) is similar for the four compounds and is roughly 1 K.

  1. Theoretical and Synthetic Study on the Existence, Structures, and Bonding of the Halide-Bridged [B2X7](-) (X = F, Cl, Br, I) Anions.

    PubMed

    Bertocco, Philipp; Bolli, Christoph; Correia Bicho, Bruno A; Jenne, Carsten; Erken, Berrin; Laitinen, Risto S; Seeger, Helene A; Takaluoma, Teemu T

    2016-04-01

    While hydrogen bridging is very common in boron chemistry, halogen bridging is rather rare. The simplest halogen-bridged boron compounds are the [B2X7](-) anions (X = F, Cl, Br, I), of which only [B2F7](-) has been reported to exist experimentally. In this paper a detailed theoretical and synthetic study on the [B2X7](-) anions is presented. The structures of [B2X7](-) anions have been calculated at the MP2/def2-TZVPP level of theory, and their local minima have been shown to be of C2 symmetry in all cases. The bonding situation varies significantly between the different anions. While in [B2F7](-) the bonding is mainly governed by electrostatics, the charge is almost equally distributed over all atoms in [B2I7](-) and additional weak iodine···iodine interactions are observed. This was shown by an atoms in molecules (AIM) analysis. The thermodynamic stability of the [B2X7](-) anions was estimated in all phases (gas, solution, and solid state) based on quantum-chemical calculations and estimations of the lattice enthalpies using a volume-based approach. In the gas phase the formation of [B2X7](-) anions from [BX4](-) and BX3 is favored in accord with the high Lewis acidity of the BX3 molecules. In solution and in the solid state only [B2F7](-) is stable against dissociation. The other three anions are borderline cases, which might be detectable under favorable conditions. However, experimental attempts to identify [B2X7](-) (X = Cl, Br, I) anions in solution by (11)B NMR spectroscopy and to prepare stable [PNP][B2X7] salts failed. PMID:26977788

  2. Antiferromagnetism in a Family of S = 1 Square Lattice Coordination Polymers NiX2(pyz)2 (X = Cl, Br, I, NCS; pyz = Pyrazine).

    PubMed

    Liu, Junjie; Goddard, Paul A; Singleton, John; Brambleby, Jamie; Foronda, Francesca; Möller, Johannes S; Kohama, Yoshimitsu; Ghannadzadeh, Saman; Ardavan, Arzhang; Blundell, Stephen J; Lancaster, Tom; Xiao, Fan; Williams, Robert C; Pratt, Francis L; Baker, Peter J; Wierschem, Keola; Lapidus, Saul H; Stone, Kevin H; Stephens, Peter W; Bendix, Jesper; Woods, Toby J; Carreiro, Kimberly E; Tran, Hope E; Villa, Cecelia J; Manson, Jamie L

    2016-04-01

    The crystal structures of NiX2(pyz)2 (X = Cl (1), Br (2), I (3), and NCS (4)) were determined by synchrotron X-ray powder diffraction. All four compounds consist of two-dimensional (2D) square arrays self-assembled from octahedral NiN4X2 units that are bridged by pyz ligands. The 2D layered motifs displayed by 1-4 are relevant to bifluoride-bridged [Ni(HF2)(pyz)2]EF6 (E = P, Sb), which also possess the same 2D layers. In contrast, terminal X ligands occupy axial positions in 1-4 and cause a staggered packing of adjacent layers. Long-range antiferromagnetic (AFM) order occurs below 1.5 (Cl), 1.9 (Br and NCS), and 2.5 K (I) as determined by heat capacity and muon-spin relaxation. The single-ion anisotropy and g factor of 2, 3, and 4 were measured by electron-spin resonance with no evidence for zero-field splitting (ZFS) being observed. The magnetism of 1-4 spans the spectrum from quasi-two-dimensional (2D) to three-dimensional (3D) antiferromagnetism. Nearly identical results and thermodynamic features were obtained for 2 and 4 as shown by pulsed-field magnetization, magnetic susceptibility, as well as their Néel temperatures. Magnetization curves for 2 and 4 calculated by quantum Monte Carlo simulation also show excellent agreement with the pulsed-field data. Compound 3 is characterized as a 3D AFM with the interlayer interaction (J⊥) being slightly stronger than the intralayer interaction along Ni-pyz-Ni segments (J(pyz)) within the two-dimensional [Ni(pyz)2](2+) square planes. Regardless of X, J(pyz) is similar for the four compounds and is roughly 1 K. PMID:27002487

  3. Theoretical study on ion-pair recognition of M(+)X(-) (M = Li, Na, K and X = F, Cl, Br) by formylaminocalix[4]arene derivatives.

    PubMed

    Xie, Ju; Jin, Guolian; Sun, Long; Feng, Wenling; Lu, Pengfei; Diao, Guowang

    2012-12-01

    DFT calculations were reported for calix[4]arene derivatives [i.e., formylaminocalix[4]arene (1) and formylaminocalix[4]bis-crown-3 (2)] binding cations M(+) (Li(+), Na(+), and K(+)) and anions X(-) (F(-), Cl(-), and Br(-)) simultaneously. The B3LYP function together with the LANL2DZp basis set was used in order to obtain insights into the factors determining the nature of the interactions of these compounds with X(-) and M(+). Based on the molecular electrostatic potential (MEP) analysis, the result complexes M(+)X(-)/H (H = 1, 2) were investigated. For all the complex structures, the most pronounced changes in geometric parameters upon interaction were observed in the host segment compared with the free receptors. Two main types of driving force, N-H∙∙∙X(-) hydrogen bonds and electrostatic interactions between M(+) and oxygen atoms, were confirmed. The recognition trends for 1 and 2 toward M(+)X(-) followed the same order: M(+)F(-) > M(+)Cl(-) > M(+)Br(-) (M(+) is same to each other) and Li(+)X(-) > Na(+)X(-) > K(+)X(-) (X(-) is same to each other). The binding energy, enthalpy change, Gibbs free energy change, and entropy change of complexation formation have been studied by the calculated thermodynamic data. In all cases, the inclusion energy changes with 2 were more negative than those with 1, correlating with the flexible space available by the two crown ether moieties in 2. The calculated results of the model system have been reported and should be useful to the experimental research in this field. PMID:22733275

  4. Insight into the substitution reactions of silylenoid H2SiLiF with GeH3X (X = F, Cl, Br): a theoretical study.

    PubMed

    Yan, Bingfei; Li, Wenzuo; Xiao, Cuiping; Li, Qingzhong; Cheng, Jianbo

    2015-04-01

    The unique substitution reactions of the three-membered-ring silylenoid H2SiLiF with GeH3X (X = F, Cl, Br) were investigated using ab initio and density functional theory calculations. All stationary points on the potential energy surfaces were optimized at the B3LYP/6-311 + G (d, p) level of theory and the QCISD method was then used to calculate the single-point energies. Theoretical calculations predicted that the substitution reactions of H2SiLiF with GeH3X proceed via two reaction paths (I and II), while forming the same product H2FSi-GeH3. In either pathway, there is one precursor complex (Q), one transition state (TS), and one intermediate (IM) connecting the reactants and products. The substitution reaction barriers of H2SiLiF with GeH3X for path I (48.49, 42.71, and 38.71 kJ mol(-1)) decreased with the increase for the same-family element X from up to down in the periodic table, whereas the substitution barriers for path II (6.51, 22.04, and 23.62 kJ mol(-1)) increased with the increase in atomic number of X (X = F, Cl, Br). Path II was more favorable than path I. All the substitution reactions of H2SiLiF with GeH3X were exothermic. The elucidation of the unique mechanism of these substitution reactions suggests a new reaction mode of silicon-germanium bond formation.

  5. Theoretical study on ion-pair recognition of M(+)X(-) (M = Li, Na, K and X = F, Cl, Br) by formylaminocalix[4]arene derivatives.

    PubMed

    Xie, Ju; Jin, Guolian; Sun, Long; Feng, Wenling; Lu, Pengfei; Diao, Guowang

    2012-12-01

    DFT calculations were reported for calix[4]arene derivatives [i.e., formylaminocalix[4]arene (1) and formylaminocalix[4]bis-crown-3 (2)] binding cations M(+) (Li(+), Na(+), and K(+)) and anions X(-) (F(-), Cl(-), and Br(-)) simultaneously. The B3LYP function together with the LANL2DZp basis set was used in order to obtain insights into the factors determining the nature of the interactions of these compounds with X(-) and M(+). Based on the molecular electrostatic potential (MEP) analysis, the result complexes M(+)X(-)/H (H = 1, 2) were investigated. For all the complex structures, the most pronounced changes in geometric parameters upon interaction were observed in the host segment compared with the free receptors. Two main types of driving force, N-H∙∙∙X(-) hydrogen bonds and electrostatic interactions between M(+) and oxygen atoms, were confirmed. The recognition trends for 1 and 2 toward M(+)X(-) followed the same order: M(+)F(-) > M(+)Cl(-) > M(+)Br(-) (M(+) is same to each other) and Li(+)X(-) > Na(+)X(-) > K(+)X(-) (X(-) is same to each other). The binding energy, enthalpy change, Gibbs free energy change, and entropy change of complexation formation have been studied by the calculated thermodynamic data. In all cases, the inclusion energy changes with 2 were more negative than those with 1, correlating with the flexible space available by the two crown ether moieties in 2. The calculated results of the model system have been reported and should be useful to the experimental research in this field.

  6. Formation of the Si-B bond: insertion reactions of silylenes into B-X(X = F, Cl, Br, O, and N) bonds.

    PubMed

    Geng, Bing; Xu, Chongjuan; Chen, Zhonghe

    2016-06-01

    The insertion reactions of the silylene H2Si with H2BXHn-1 (X = F, Cl, Br, O, N; n = 1, 1, 1, 2, 3) have been studied by DFT and MP2 methods. The calculations show that the insertions occur in a concerted manner, forming H2Si(BH2)(XHn-1). The essences of H2Si insertions with H2BXHn-1 are the transfers of the σ electrons on the Si atom to the positive BH2 group and the electrons of X into the empty p orbital on the Si atom in H2Si. The order of reactivity in vacuum shows the barrier heights increase for the same-family element X from up to down and the same-row element X from right to left in the periodic table. The energies relating to the B-X bond in H2BXHn-1, and the bond energies of Si-X and Si-B in H2Si(BH2)(XHn-1) may determine the preference of insertions of H2Si into B-X bonds for the same-column element X or for the same-row element X. The insertion reactions in vacuum are similar to those in solvents, acetone, ether, and THF. The barriers in vacuum are lower than those in solvents and the larger polarities of solvents make the insertions more difficult to take place. Both in vacuum and in solvents, the silylene insertions are thermodynamically exothermic. Graphical Abstract The insertion process of H2Si and H2BXHn-1(X = F, Cl, Br, O, and N; n = 1, 1 , 1, 2, 3).

  7. Rotationally adiabatic pair interactions of para- and ortho-hydrogen with the halogen molecules F2, Cl2, and Br2

    NASA Astrophysics Data System (ADS)

    Berg, Matthias; Accardi, Antonio; Paulus, Beate; Schmidt, Burkhard

    2014-08-01

    The present work is concerned with the weak interactions between hydrogen and halogen molecules, i.e., the interactions of pairs H2-X2 with X = F, Cl, Br, which are dominated by dispersion and quadrupole-quadrupole forces. The global minimum of the four-dimensional (4D) coupled cluster with singles and doubles and perturbative triples (CCSD(T)) pair potentials is always a T shaped structure where H2 acts as the hat of the T, with well depths (De) of 1.3, 2.4, and 3.1 kJ/mol for F2, Cl2, and Br2, respectively. MP2/AVQZ results, in reasonable agreement with CCSD(T) results extrapolated to the basis set limit, are used for detailed scans of the potentials. Due to the large difference in the rotational constants of the monomers, in the adiabatic approximation, one can solve the rotational Schrödinger equation for H2 in the potential of the X2 molecule. This yields effective two-dimensional rotationally adiabatic potential energy surfaces where pH2 and oH2 are point-like particles. These potentials for the H2-X2 complexes have global and local minima for effective linear and T-shaped complexes, respectively, which are separated by 0.4-1.0 kJ/mol, where oH2 binds stronger than pH2 to X2, due to higher alignment to minima structures of the 4D-pair potential. Further, we provide fits of an analytical function to the rotationally adiabatic potentials.

  8. Absorption characteristics of anions (I-, Br-, and Te2-) into zeolite in molten LiCl-KCl eutectic salt

    NASA Astrophysics Data System (ADS)

    Uozumi, Koichi; Sugihara, Kei; Kinoshita, Kensuke; Koyama, Tadafumi; Tsukada, Takeshi; Terai, Takayuki; Suzuki, Akihiro

    2014-04-01

    The behaviors of anion fission product (FP) elements to be absorbed into zeolite in molten LiCl-KCl eutectic salt were studied using iodine, bromine, and tellurium. First, the type-A zeolite was selected as the most suitable type of zeolite among type-A, type-X, and type-Y zeolites through experiments in which zeolites were heated together with LiCl-KCl-KI salt. As the next step, experiments in which the type-A zeolite was immersed in molten LiCl-KCl salt containing various concentrations of iodine, bromine, or tellurium were performed. The degree of absorption of the anion FP elements was evaluated using the separation factor (SF) value versus chlorine. Although the SF values for iodine and tellurium were higher than 1.0, which meant that these elements were absorbed into the type-A zeolite more intensively than chlorine in the salt, the corresponding value for bromine was approximately 1.0. The effects of coexisting cation FPs were also examined using cesium, strontium, and neodymium, and it was revealed that the SF values for iodine were less than those in the case without cation addition. On the other hand, the SF values for tellurium were not affected by the coexistence of cesium and strontium. Finally, the feasibility of the present pyroprocess flowsheet was evaluated by calculating the inventory of each anion FP in an electrorefiner based on the obtained SF values instead of temporary values for the anion FPs absorption, which were set due to lack of experimental data.

  9. 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.

  10. 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. PMID:26702973

  11. Relativistic effects on nuclear magnetic shieldings of CHnX4-n and CHXYZ (X, Y, Z = H, F, Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Melo, Juan I.; Maldonado, Alejandro F.; Aucar, Gustavo A.

    2012-12-01

    Nuclear magnetic shieldings of both carbon and hydrogen atoms of haluro methyl molecules are highly influenced by the substitution of one or more hydrogen by halogen heavy atoms. We applied the linear response elimination of small components, LRESC, formalism to calculate such shieldings and learn whether including only few terms is enough for getting quantitative reproduction of the total shieldings or not. First, we discuss the contribution of all leading relativistic corrections to σ(C), in CHX2I molecular models with X = H, F, and Cl, and show that spin-orbit (SO) effects are the main ones. After adding the SO effects to the non-relativistic (NR) results, we obtain ˜ 97% (93%) of the total LRESC values for σ(C) (σ(H)). The magnitude of SO terms increases when the halogen atom becomes heavier. In this case, such contributions to σ(C) can be extrapolated as a function of Z, the halogen atomic number. Furthermore, when paramagnetic spin-orbit (PSO) contributions are also considered, we obtain results that are within 1% of the total LRESC value. Then we study in detail the main electronic mechanisms involved to contribute C and H shieldings on CHnX4 - n (n = 1, 3), and CHXYZ (X, Y, Z = F, Cl, Br, I) model compounds. The pattern of σ(C) for all series of compounds follows a normal halogen dependence (NHD), though with different rate of increase. A special family of compounds is that of CHF2X for which σnr(C) follows an inverse halogen dependence though the total shielding have a NHD due to the SO contributions. For the series CH3X (X = F, Cl, Br and I), we found that σSO ˜ Z_X^{2.53}. Another important finding of this work is the logarithmic dependence of σSO(C) with the substituent atomic number: ln σSO(C) = A_X + a_X Z_Y for both family of compounds CH2XY and CHX2Y. We also performed four-component calculations using the spin-free Hamiltonian to obtain SO contributions within a four-component framework.

  12. Relativistic effects on nuclear magnetic shieldings of CH(n)X(4-n) and CHXYZ (X, Y, Z = H, F, Cl, Br, I).

    PubMed

    Melo, Juan I; Maldonado, Alejandro F; Aucar, Gustavo A

    2012-12-01

    Nuclear magnetic shieldings of both carbon and hydrogen atoms of haluro methyl molecules are highly influenced by the substitution of one or more hydrogen by halogen heavy atoms. We applied the linear response elimination of small components, LRESC, formalism to calculate such shieldings and learn whether including only few terms is enough for getting quantitative reproduction of the total shieldings or not. First, we discuss the contribution of all leading relativistic corrections to σ(C), in CHX(2)I molecular models with X = H, F, and Cl, and show that spin-orbit (SO) effects are the main ones. After adding the SO effects to the non-relativistic (NR) results, we obtain ~ 97% (93%) of the total LRESC values for σ(C) (σ(H)). The magnitude of SO terms increases when the halogen atom becomes heavier. In this case, such contributions to σ(C) can be extrapolated as a function of Z, the halogen atomic number. Furthermore, when paramagnetic spin-orbit (PSO) contributions are also considered, we obtain results that are within 1% of the total LRESC value. Then we study in detail the main electronic mechanisms involved to contribute C and H shieldings on CH(n)X(4 - n) (n = 1, 3), and CHXYZ (X, Y, Z = F, Cl, Br, I) model compounds. The pattern of σ(C) for all series of compounds follows a normal halogen dependence (NHD), though with different rate of increase. A special family of compounds is that of CHF(2)X for which σ(nr)(C) follows an inverse halogen dependence though the total shielding have a NHD due to the SO contributions. For the series CH(3)X (X = F, Cl, Br and I), we found that σ(SO) ~ Z(X) (2.53). Another important finding of this work is the logarithmic dependence of σ(SO)(C) with the substituent atomic number: ln σ(SO)(C) = A(X) + a(X) Z(Y) for both family of compounds CH(2)XY and CHX(2)Y. We also performed four-component calculations using the spin-free Hamiltonian to obtain SO contributions within a four-component framework.

  13. Magnetic and structural phase transitions of multiferroic boracites M3B7O13X (M =3 d transition metal Cr-Zn or Mg; X =halogen Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Schnelle, Walter; Schmid, Hans

    2015-05-01

    The specific heat capacity of mostly single-crystalline samples of 21 boracite compounds M3B7O13X with M a 3 d transition metal (Cr, Mn, Fe, Co, Ni, Cu, Zn) or Mg and X a halogen (Cl, Br, I) is determined. In combination with magnetic susceptibility data the magnetic ordering of the M2 + ions at TN is investigated in detail. The fully ferroelectric/fully ferroelastic structural phase transitions at higher temperatures are measured by differential scanning calorimetry. In the Cr-Br, Cr-I, Cu-Cl, and Cu-Br compounds, previously unknown magnetic phases were found. Magnetic order in the boracites is characterized by the quantum and classical spin states of the M2 + ions, a variable degree of structural distortion, orbital effects, and competing exchange interactions. The Cu-Cl, Cu-Br, and Ni-Cl boracites exhibit broad maxima of magnetic specific heat and of magnetic susceptibility above TN caused by low-dimensional or frustrated magnetic interactions. Co boracites display additional broad anomalies below TN originating from continuous spin reorientations and effective S =1 /2 ground states. Indications for spin reorientations are also observed for Fe boracites. New phases appear in high magnetic fields for some Co and Fe boracites, which is not the case for the Mn compounds. Stronger magnetic frustration is deduced for the cubic Cr compounds. For the latter compounds and Ni-I boracite magnetostructural phase transitions are observed.

  14. 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.

  15. Nqrs Data for AlCa2ClH10O8 [AlCa2ClO3·5(H2O)] (Subst. No. 0020)

    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 AlCa2ClH10O8 [AlCa2ClO3·5(H2O)] (Subst. No. 0020)

  16. LiAl/Cl/sub 2/ battery with a four-component alkali-metal chloride electrolyte

    SciTech Connect

    Thomas, D.L.

    1986-01-01

    A LiAl/Cl/sub 2/ cell operating at 280/sup 0/ was demonstrated. The electrolyte is a mixture of LiCl, KCl, RbCl, and CsCL with a eutectic melting point of 258/sup 0/C. Physical properties of the melt and the Cl/sub 2/-melt system were measured. Two types of Cl/sub 2/ electrodes were tested. The discharge current in the flow-through Cl/sub 2/ electrode was limited by the high viscosity of the electrolyte (40 cP), which limited the flow rate and Cl/sub 2/ supply through the graphite cloth electrode. Currents as high as 50 mA/cm/sup 2/ were observed with the gas-diffusion Cl/sub 2/ electrode. The capacity of the cell was limited by the LiAl electrode. The gas-diffusion electrode reaction volume was modeled as a meniscus film in a cylindrical pore. The model indicates that high polarization of the positive electrode is caused by the small ratio of film cross-sectional area to pore cross-sectional area, necessitating high film currents to support modest bulk electrolyte currents. Modeling indicated that the negative electrode rate was limited by solid-state diffusion of Li through the LiAl.

  17. 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. PMID:19756276

  18. 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.

  19. 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

    2015-08-01

    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. PMID:26083320

  20. 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. PMID:27425405

  1. FT-IR, FT-Raman and DFT study of 3,3'-bis (trifluoromethyl) benzophenone and its biological activity with other halogen (Cl, Br) atoms.

    PubMed

    Mahalakshmi, G; Balachandran, V

    2014-04-24

    The FT-IR and FT-Raman spectra of 3,3'-bis (trifluoromethyl) benzophenone (TFMBP) were recorded and analyzed. Natural bond orbital analysis on TFMBP, 3,3'-bis (trichloromethyl) benzophenone (TCMBP) and 3,3'-bis (tribromomethyl) benzophenone (TBMBP) has been carried out for various intramolecular interactions that are responsible for the stabilization of the molecule. HOMO-LUMO energy gap of the halogen substitution (Cl, Br) has been computed with the help of density functional theory. The statistical thermodynamic functions (heat capacity, entropy, vibrational partition function and Gibbs energy) were obtained for the range of temperature 100-1000 K. The polarizability, first hyperpolarizability, anisotropy polarizability invariant has been computed using quantum chemical calculations. The infrared and Raman spectra were also predicted from the calculated intensities. Comparison of the experimental and theoretical spectra values provides important information about the ability of the computational method to describe the vibrational modes. UV-VIS spectral analyses of TFMBP have been researched by theoretical calculations. In order to understand electronic transitions of the compound, TD-DFT calculations on electronic absorption spectra in gas phase and solvent (DMSO and Chloroform) were performed. The calculated frontier orbital energies, absorption wavelengths (λ), oscillator strengths (ƒ) and excitation energies (E) for gas phase and solvent (water and methanol) are also illustrated. PMID:24503154

  2. 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.

  3. Direct evaluation of the hyperconjugative interactions in 1,1,1-trihaloethane (CH3CX3, X = F, Cl, and Br).

    PubMed

    Chen, Zhenhua; Corminboeuf, Clémence; Mo, Yirong

    2014-08-01

    Following the computational strategy proposed by Mulliken in 1939 ( J. Chem. Phys. 1939, 7 (5), 339-352), when the concept of hyperconjugation was coined, we evaluated the hyperconjugative stabilization energy in 1,1,1-trihaloethane using the block-localized wave function (BLW) method. The BLW method is the simplest and most efficient variant of ab initio valence bond (VB) theory and can derive the strictly electron-localized state wave function self-consistently. The latter serves as a reference for the quantification of the electron delocalization effect in terms of the resonance theory. Computations show that the overall hyperconjugative interactions in 1,1,1-trihaloethane, dominated by σ(CH) → σ'(CX) with minor contribution from σ(CX) → σ'(CH), ranges from 9.59 to 7.25 kcal/mol in the staggered structures and decreases in the order Br > Cl > F. This is in accord with the (1)H NMR spectra of CH3CX3. Notably, the hyperconjugation effect accounts for 35-40% of the rotation barriers in these molecules, which are dominated by the conventional steric repulsion. This is consistent with the recent findings with 1,2-difluoroethane (Freitas, Bühl, and O'Hagan. Chem. Comm. 2012, 48, 2433-2435) that the variation of (1)J(CF) with the FCCF torsional angle cannot be well explained by the hyperconjugation model

  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

    2015-08-01

    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. Theoretical study of the nuclear spin-molecular rotation coupling for relativistic electrons and non-relativistic nuclei. II. Quantitative results in HX (X = H,F,Cl,Br,I) compounds.

    PubMed

    Aucar, I Agustín; Gómez, Sergio S; Melo, Juan I; Giribet, Claudia C; Ruiz de Azúa, Martín C

    2013-04-01

    In the present work, numerical results of the nuclear spin-rotation (SR) tensor in the series of compounds HX (X = H,F,Cl,Br,I) within relativistic 4-component expressions obtained by Aucar et al. [J. Chem. Phys. 136, 204119 (2012)] are presented. The SR tensors of both the H and X nuclei are discussed. Calculations were carried out within the relativistic Linear Response formalism at the Random Phase Approximation with the DIRAC program. For the halogen nucleus X, correlation effects on the non-relativistic values are shown to be of similar magnitude and opposite sign to relativistic effects. For the light H nucleus, by means of the linear response within the elimination of the small component approach it is shown that the whole relativistic effect is given by the spin-orbit operator combined with the Fermi contact operator. Comparison of "best estimate" calculated values with experimental results yield differences smaller than 2%-3% in all cases. The validity of "Flygare's relation" linking the SR tensor and the NMR nuclear magnetic shielding tensor in the present series of compounds is analyzed.

  6. New ionic liquids based on the complexation of dipropyl sulfide and AlCl3 for electrodeposition of aluminum.

    PubMed

    Fang, Youxing; Jiang, Xueguang; Sun, Xiao-Guang; Dai, Sheng

    2015-09-01

    A new kind of ionic liquid based on the 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 × 10(-4) S cm(-1). This new ionic liquid can be successfully used as an electrolyte for electrodeposition of aluminum.

  7. New ionic liquids based on complexation of dipropylsulfide and AlCl3 for electrochodeposition of aluminum

    DOE PAGES

    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.

  8. Crystalline Al1 - x Ti x phases in the hydrogen cycled NaAlH4 + 0.02TiCl3 system

    NASA Astrophysics Data System (ADS)

    Pitt, M. P.; Vullum, P. E.; Sørby, M. H.; Emerich, H.; Paskevicius, M.; Buckley, C. E.; Gray, E. MacA.; Walmsley, J. C.; Holmestad, R.; Hauback, B. C.

    2013-03-01

    The hydrogen (H) cycled planetary milled (PM) NaAlH4 + 0.02TiCl3 system has been studied by high resolution synchrotron X-ray diffraction and transmission electron microscopy during the first 10 H cycles. After the first H absorption, we observe the formation of four nanoscopic crystalline (c-) Ti-containing phases embedded on the NaAlH4 surface, i.e. Al2Ti, Al3Ti, Al82Ti18 and Al89Ti11, with 100% of the originally added Ti atoms accounted for. Al2Ti and Al3Ti are observed morphologically as a mechanical couple on the NaAlH4 surface, with a moderately strained interface. Electron diffraction shows that the Al82Ti18 phase retains some ordering from the L12 structure type, with the observation of forbidden (100) ordering reflections in the fcc Al82Ti18 lattice. After 2 H cycles the NaAlH4 + 0.02TiCl3 system displays only two crystalline Ti-containing phases, Al3Ti and Al89Ti11. After 10 H cycles, the Al89Ti11 is completely converted to Al85Ti15. Al89Ti11, Al85Ti15 and Al3Ti do not display any ordering reflections, and they are modeled in the A1 structure type. Quantitative phase analysis indicates that the Al3Ti proportion continues to increase with further H cycles. The formation of Ti-poor Al1 - x Ti x (x < 0.25) phases in later H cycles is detrimental to hydrogenation kinetics, compared to the starting Ti-richer near-surface Al2Ti/NaAlH4 interface present during the first absorption of hydrogen.

  9. 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.

  10. Chemical vapor deposition of aluminosilicates from mixtures of SiCl{sub 4}, AlCl{sub 3}, CO{sub 2}, and H{sub 2}

    SciTech Connect

    Nitodas, S.F.; Sotirchos, S.V.

    2000-03-01

    A comprehensive study of the chemical vapor codeposition of silica, alumina, and aluminosilicates from SiCl{sub 4}-AlCl{sub 3}-H{sub 2}-CO{sub 2} mixtures is presented. A hot-wall reactor, coupled to an electronic microbalance, is used to investigate the dependence of the deposition rate on temperature, pressure, composition, and total flow rate over a broad range of operating conditions. The experimental observations are discussed in the context of the results obtained in independent deposition experiments of silica and alumina from mixtures of SiCl{sub 4}-H{sub 2}-CO{sub 2} and AlCl{sub 3}H{sub 2}-CO{sub 2}, respectively, in the same apparatus. The results show that the deposition of silica proceeds at very low rates that are by more than an order of magnitude lower than those of alumina deposition at the same temperature, pressure, total flow rate, and carbon dioxide and chloride mole fractions in the feed. When both chlorides (SiCl{sub 4} and AlCl{sub 3}) are fed to the reactor, that is, in the codeposition process, the rate of SiO{sub 2} deposition is much higher than that seen in the single species deposition experiments, while the opposite behavior is observed for the rate of deposition of Al{sub 2}O{sub 3}. The results of deposition experiments conducted on refractory wires, in order to obtain information on the effect of the substrate position in the reactor, show that manipulation of residence time offers a way to control the composition of the codeposited films in alumina and silica. The experimental results are compared with those obtained in a past study using methyltrichlorosilane as silicon source.

  11. Effects of AlCl3 on toad skin, human erythrocytes, and model cell membranes.

    PubMed

    Suwalsky, M; Ungerer, B; Villena, F; Norris, B; Cárdenas, H; Zatta, P

    2001-05-15

    Aluminum, a very abundant metal, could play a toxic role in several pathological processes, including neurodegeneration. Although the effects of Al(III) on biological membranes have been extensively described, direct information concerning the molecular basis of its biological activity is rather scanty. To examine aluminum challenges on cell membranes, various concentrations of AlCl3 in aqueous solutions were incubated with human erythrocytes, isolated toad skin, and molecular models of biomembranes. The latter consisted of multilayers of dimyristoylphosphatidylcholine and dimyristoylphosphatidylethanolamine, representing phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane. These specimens were studied by scanning electron microscopy, electrophysiological measurements, and x-ray diffraction. The results indicate that Al(III) in the concentration range of 10-100 microM induced the following structural and functional effects: (i) change in the normal discoid shape of human erythrocytes to echinocytes due to the accumulation of Al(III) ions in the outer moiety of the red cell membrane; (ii) perturbation of dimyristoylphosphatidylcholine, and to a lesser extent of dimyristoylphosphatidylethanolamine bilayers, and (iii) decrease in the short-circuit current and in the potential difference of the isolated toad skin, effects that are in accordance with a time-dependent modulation of ion transport in response to changes in the molecular structure of the lipid bilayer. PMID:11470316

  12. 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.

  13. Pt(CN)2-4 and Au(CN)-2: potential general probes for anion-binding sites of proteins. 35Cl and 81Br nuclear-magnetic-resonance studies.

    PubMed

    Norne, J E; Lilja, H; Lindman, B; Einarsson, R; Zeppezauer, M

    1975-11-15

    Nuclear magnetic quadrupole relaxation appears to be a general method for studying the binding of anions to proteins. This is shown by the increase in transverse quadrupole relaxation rate of 35Cl- and 81Br- in the presence of horse liver alcohol dehydrogenase, lysozyme, trypsin, alpha-chymotrypsin, human carbonic anhydrase, fructose-1,6-bisphosphate aldolase and human serum albumin. Of the many possible binding sites at the surface of a protein (e.g. positively charged amino acid side-chains) only a few account for the main part of the relaxation enhancement. This is shown by the decrease in 35Cl- and 81Br- relaxation rate on addition of functional ligands. Large, kinetically inert, complex anions like Pt(CN)2-4 and Au(CN)-2 are found to act as strong competitors towards halogen ions for the high-affinity anion binding sites of a number of proteins. Titrations with complex anions following the 35Cl- or 81Br- relaxation rates are found to be helpful in attempts to elucidate binding mechanisms. Especially, the complex anions may be useful probes for the discrimination between general and metallic anion binding sites in proteins and they also permit correlation of information from X-ray investigations of crystals with that from physical measurements in solution. From the change in halide ion quadrupole relaxation rate on addition of strongly binding ligands the quadrupole coupling constants of the high affinity Cl- and Br- binding sites are estimated using certain assumptions. It is found that for several proteins, comprising the metal-free proteins but also alcohol dehydrogenase and Escherichia coli alkaline phosphatase, the 35Cl quadrupole coupling constants have approximately the same values. For some other metallo-proteins like carbonic anhydrase and a zinc - serum-albumin complex considerably greater quadrupole coupling constants were obtained. The estimated quadrupole coupling constants are used as a basis for a discussion of the interactions involved in anion

  14. 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)

  15. 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.

  16. A LiAl/Cl sub 2 battery with a four-component alkali-metal chloride electrolyte

    SciTech Connect

    Thomas, D.L. ); Bennion, D.N. )

    1989-01-01

    A LiAl/Cl{sub 2} cell operating at 280{degrees}C was investigated. The electrolyte is a mixture of LiCl, KCl, RbCl, and CsCl with a eutectic melting point of 258 {degrees}C. The positive electrode is a gas-diffusion electrode formed by coating one side of a porous carbon electrode with PTFE. The limiting discharge current of the cell was controlled by solid-state diffusion of Li in the LiA1 alloy. Polarization of the Cl{sub 2} 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{sup +}, in the electrolyte. Mathematical models of the negative and positive electrodes in a LiAl/Cl{sub 2} cell with a gas diffusion Cl{sub 2} 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. The thin film is liquid salt on the porous electrode walls through which chlorine diffuses.

  17. 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.

  18. 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. PMID:27102131

  19. ESR of Mn2+ in AlCl3-graphite intercalated compounds

    NASA Astrophysics Data System (ADS)

    Ceotto, G.; Barberis, G. E.; Rettori, C.

    1989-05-01

    Electron-spin-resonance experiments of Mn2+ impurities in stage-2 AlCl3-graphite intercalated compounds show the usual conduction-carrier spin resonance and a completely resolved Mn2+ spectrum of axial symmetry with the axial axis perpendicular to the carbon layers. The temperature dependence of the Mn2+ second-order crystal-field parameter and spin-lattice relaxation time are reported. The hyperfine splittings were found to be temperature independent. The observed anomalies in the linewidth of the conduction-carrier spin resonance and the intensity of the Mn2+ resonance at T~=200 K are interpreted in terms of a quasi-two-dimensional order-disorder phase transition experienced by the intercalant molecules at this temperature.

  20. Magnitude and Directionality of Halogen Bond of Benzene with C6F5X, C6H5X, and CF3X (X = I, Br, Cl, and F).

    PubMed

    Tsuzuki, Seiji; Uchimaru, Tadafumi; Wakisaka, Akihiro; Ono, Taizo

    2016-09-01

    Geometries of benzene complexes with C6F5X, C6H5X, and CF3X (X is I, Br, Cl, and F) were optimized, and their interaction energies were evaluated. The CCSD(T) interaction energies at the basis set limit (Eint) of C6F5X (X is I, Br, Cl, and F) with benzene were -3.24, -2.88, -2.31, and -0.92 kcal mol(-1). Eint of C6H5X (X is I, Br, and Cl) with benzene were -2.31, -1.97, and -1.48 kcal mol(-1). The fluorination of halobenzenes slightly enhances the attraction. Eint of CF3X (X is I, Br, Cl, and F) with benzene (-3.11, -2.74, -2.22, and -0.71 kcal mol(-1)) were very close to Eint of corresponding C6F5X with benzene. In contrast to the halogen bond of iodine and bromine with pyridine (n-type halogen bond acceptor) where the main cause of the attraction is the electrostatic interactions, that of halogen bond with benzene (p-type acceptor) is dispersion interaction. In the halogen bonds with p-type acceptors (halogen-π interactions), the electrostatic interactions and induction interactions are small. The overall orbital-orbital interactions are repulsive. The directionality of halogen bonds with p-type acceptors is very weak, owing to the weak electrostatic interactions, in contrast to the strong directionality of the halogen bonds with n-type acceptors and hydrogen bonds. PMID:27525985

  1. 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

    Wallevik, Sunna Ó; Bjornsson, Ragnar; Kvaran, Agúst; Jonsdottir, Sigridur; Arnason, Ingvar; Belyakov, Alexander V; Kern, Thomas; Hassler, Karl

    2013-12-01

    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 (E axial - E equatorial) 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

  2. Effect of pressure on the interlayer transport and the electronic structure in the organic quasi-two-dimensional bilayer metal θ-(BETS)4HgBr4(C6H5Cl)

    NASA Astrophysics Data System (ADS)

    Lyubovskii, R. B.; Pesotskii, S. I.; Zhilyaeva, E. I.; Lyubovskaya, R. N.

    2016-01-01

    The behavior of the interlayer resistance and the magnetoresistance in the organic quasi-twodimensional bilayer metal θ-(BETS)4HgBr4(C6H5Cl) is studied at normal pressure and a hydrostatic pressure of 10 kbar. The interlayer transport under atmospheric pressure is found to occur in an incoherent mode. The applied pressure does not change the electronic structure of the conducting layers and causes a transition to a weakly coherent mode at low temperatures.

  3. 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

  4. Magnitude and Directionality of Halogen Bond of Benzene with C6F5X, C6H5X, and CF3X (X = I, Br, Cl, and F).

    PubMed

    Tsuzuki, Seiji; Uchimaru, Tadafumi; Wakisaka, Akihiro; Ono, Taizo

    2016-09-01

    Geometries of benzene complexes with C6F5X, C6H5X, and CF3X (X is I, Br, Cl, and F) were optimized, and their interaction energies were evaluated. The CCSD(T) interaction energies at the basis set limit (Eint) of C6F5X (X is I, Br, Cl, and F) with benzene were -3.24, -2.88, -2.31, and -0.92 kcal mol(-1). Eint of C6H5X (X is I, Br, and Cl) with benzene were -2.31, -1.97, and -1.48 kcal mol(-1). The fluorination of halobenzenes slightly enhances the attraction. Eint of CF3X (X is I, Br, Cl, and F) with benzene (-3.11, -2.74, -2.22, and -0.71 kcal mol(-1)) were very close to Eint of corresponding C6F5X with benzene. In contrast to the halogen bond of iodine and bromine with pyridine (n-type halogen bond acceptor) where the main cause of the attraction is the electrostatic interactions, that of halogen bond with benzene (p-type acceptor) is dispersion interaction. In the halogen bonds with p-type acceptors (halogen-π interactions), the electrostatic interactions and induction interactions are small. The overall orbital-orbital interactions are repulsive. The directionality of halogen bonds with p-type acceptors is very weak, owing to the weak electrostatic interactions, in contrast to the strong directionality of the halogen bonds with n-type acceptors and hydrogen bonds.

  5. Effect of trace amounts of NaCl vapor on high-temperature oxidation of TiAl

    SciTech Connect

    Hara, M.; Kitagawa, Y.

    1999-08-01

    The effect of trace amounts of NaCl vapor on the high-temperature oxidation of TiAl was examined by thermogravimetry and analysis of the scale formed on TiAl. The mass gain due to oxidation at 1273 K in O{sub 2} with trace amounts of NaCl vapor was far lower than that in pure O{sub 2} without NaCl vapor. This low mass gain in the atmosphere with trace amounts of NaCl vapor resulted from the saturation behavior of mass gain during the initial period of oxidation. It was found from X-ray photoemission spectroscopy (XPS) analyses of the specimen surface that the oxide film formed during the initial period in the atmosphere with trace amounts of NaCl vapor consisted of dense Al{sub 2}O{sub 3}, thus, the low oxidation rate of TiAl was attributed to a protective oxide film of dense Al{sub 2}O{sub 3}.

  6. 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.

  7. 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.

  8. 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).

  9. Corrosion Performance Based on the Microstructural Array of Al-Based Monotectic Alloys in a NaCl Solution

    NASA Astrophysics Data System (ADS)

    Osório, Wislei R.; Freitas, Emmanuelle S.; Garcia, Amauri

    2014-01-01

    The aim of this study is to compare the electrochemical behavior of three monotectic Al-based alloys (Al-Pb, Al-Bi, and Al-In) in a 0.5 M NaCl solution at room temperature. Two distinct microstructure arrays were experimentally obtained for each Al monotectic alloy by using a water-cooled unidirectional solidification system. Results of electrochemical impedance spectroscopy (EIS) plots, potentiodynamic polarization curves, and impedance parameters obtained by an equivalent circuit analysis are discussed. It was found that the Al-Pb alloy has lower corrosion current density, higher polarization resistance, lower relative weight, and cost than the corresponding values of Al-Bi and Al-In alloys. It is also shown that the electrochemical behavior of the three alloys examined are intimately correlated with the scale of the corresponding microstructure, with smaller droplets and spacings (i.e., cell and interphase spacings) being associated with a decrease in the corrosion resistance.

  10. 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.

  11. Ibuprofen targets neuronal pentraxins expresion and improves cognitive function in mouse model of AlCl3-induced neurotoxicity

    PubMed Central

    JAMIL, ANUM; MAHBOOB, AAMRA; AHMED, TOUQEER

    2016-01-01

    Aluminum is known to exert neurotoxic effects associated with various neurodegenerative disorders, including Alzheimer's disease (AD). Ibuprofen is a well-known non-steroidal anti-inflammatory drug, which has demonstrated potential efficacy in the treatment of numerous inflammatory and neurodegenerative disorders, including AD. The present study aimed to investigate the protective effects of ibuprofen on cognitive function, and the expression levels of neuronal pentraxins (NPs) and interleukin (IL)-1β in an aluminum chloride (AlCl3)-induced mouse model of neurotoxicity. The effects of ibuprofen (100 mg/kg/day for 12 days) on learning and memory were evaluated in the AlCl3-induced neurotoxic mice using a Morris water maze and open field tests. In addition, ibuprofen was assessed for its effects on the expression levels of NPs and IL-1β in the hippocampus, cortex and amygdala of the brain. Treatment of the AlCl3-treated mice with ibuprofen decreased anxiety levels (6.90±0.34 min) compared with the AlCl3-treated group (1.80±0.29 min), as indicated by the time spent in the central area in an open field test. Furthermore, the expression levels of NP1 (1.32±0.47) and IL-1β (0.99±0.21) were significantly decreased in the hippocampus of mice following ibuprofen treatment, as compared with the AlCl3-treated mice (8.62±1.54 and 7.47±0.53, respectively). In the present study, ibuprofen was able to target novel structures in order to attenuate the inflammation associated with an AlCl3-induced mouse model of neurotoxicity; thus suggesting that ibuprofen may be considered a potential therapeutic option for the treatment of neurodegenerative diseases, including AD. PMID:26893653

  12. Heats of formation and bond energies of the H(3-n)BX(n) compounds for (X = F, Cl, Br, I, NH2, OH, and SH).

    PubMed

    Grant, Daniel J; Dixon, David A

    2009-01-29

    Atomization energies at 0 K and heats of formation at 0 and 298 K are predicted for the borane compounds H(3-n)BX(n) for (X = F, Cl, Br, I, NH2, OH, and SH) and various radicals from coupled cluster theory (CCSD(T)) calculations with an effective core potential correlation-consistent basis set for I. In order to achieve near chemical accuracy (+/-1.5 kcal/mol), three corrections were added to the complete basis set binding energies calculated from frozen core coupled cluster theory energies: a correction for core-valence effects, a correction for scalar relativistic effects, and a correction for first-order atomic spin-orbit effects. Vibrational zero point energies were computed at the MP2 level. The calculated heats of formation are in excellent agreement with the available experimental data for the closed shell molecules, but show larger differences with the reported "experimental" values for the BX2 radicals. The heats of formation of the BX2 radicals were also calculated at the G3(MP2) level of theory, and the values were in excellent agreement with the more accurate CCSD(T) values. On the basis of extensive comparisons with experiment for a wide range of compounds, our calculated values for these radicals should be good to +/-1.5 kcal/mol and thus are to be preferred over the experimental values. The accurately calculated heats of formation allow us to predict the B-X and B-H adiabatic bond dissociation energies (BDEs) to within +/-1.5 kcal/mol. The B-F BDEs in the H(3-n)BF(n) compounds and in BF (1Sigma+) are the largest BDEs in comparison to the other substituents that were investigated. The second and third largest B-X BDEs in the H(3-n)BX(n) and BX compounds are predicted for X = OH and NH2, respectively. The substituents have a minimal effect on the B-H BDEs in HBX2 and H2BX compared to the first B-H BDE of borane. The differences in adiabatic and diabatic BDEs, which are related to the reorganization energy in the product, can be estimated from singlet

  13. 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.

  14. PACAP and its receptors in migraine pathophysiology: Commentary on Walker et al., Br J Pharmacol 171: 1521–1533

    PubMed Central

    Edvinsson, Lars

    2015-01-01

    Linked Article This article is a Commentary on Walker CS, Sundrum T and Hay DL (2014). PACAP receptor pharmacology and agonist bias: analysis in primary neurons and glia from the trigeminal ganglia and transfected cells. Br J Pharmacol 171: 1521–1553. doi: 10.1111/bph.12541 PMID:24826981

  15. Synthetic, Infrared, 1H and 13C NMR Spectral Studies on N-(2/3/4-Substituted Phenyl)-2,4-Disubstituted Benzenesulphonamides, 2,4-(CH3)2/2-CH3-4-Cl/2,4-Cl2C6H3SO2NH(i-XC6H4) (i-X = H, 2-CH3, 3-CH3, 4-CH3, 2-Cl, 3-Cl, 4-Cl, 4-F, 4-Br)

    NASA Astrophysics Data System (ADS)

    Basappa, Savitha M.; Gowda, Basavalinganadoddy Thimme

    2006-11-01

    Twenty six N-(2/3/4-substituted phenyl)-2,4-disubstituted benzenesulphonamides of the general formulae 2,4-(CH3)2C6H3SO2NH(i-XC6H4), 2-CH3-4-ClC6H3SO2NH(i-XC6H4) and 2,4- Cl2C6H3SO2NH(i-XC6H4), where i-X = H, 2-CH3, 3-CH3, 4-CH3, 2-Cl, 3-Cl, 4-Cl, 4-F or 4-Br, have been prepared, characterized and their infrared spectra in the solid state and 1H and 13C NMR spectra in solution studied. The infrared N-H stretching vibrational frequencies vary in the range 3298 - 3233 cm-1. Asymmetric and symmetric SO stretching vibrations appear in the ranges 1373 - 1311 cm-1 and 1177 - 1140 cm-1, respectively, while C-S, S-N and C-N stretching absorptions vary in the ranges 840 - 812 cm-1, 972 - 908 cm-1 and 1295 - 1209 cm-1, respectively. The various 1H and 13C NMR chemical shifts are assigned to the protons and carbon atoms of the two benzene rings in line with those for similar compounds. The incremental shifts due to the groups in the parent compounds have been computed by comparing the chemical shifts of the protons or carbon atoms in these compounds with those of benzene or aniline, respectively. The computed incremental shifts and other data were used to calculate the 1H and 13C NMR chemical shifts of the substituted compounds in three different ways. The calculated chemical shifts by the three methods compared well with each other and with the observed chemical shifts. It is observed that there are no particular trends in the variation of either the infrared absorption frequencies or the chemical shifts with the nature or site of substitution.

  16. Mixed-Halide CH3 NH3 PbI3-x Xx (X=Cl, Br, I) Perovskites: Vapor-Assisted Solution Deposition and Application as Solar Cell Absorbers.

    PubMed

    Sedighi, Rahime; Tajabadi, Fariba; Shahbazi, Saeed; Gholipour, Somayeh; Taghavinia, Nima

    2016-08-01

    There have been recent reports on the formation of single-halide perovskites, CH3 NH3 PbX3 (X=Cl, Br, I), by means of vapor-assisted solution processing. Herein, the successful formation of mixed-halide perovskites (CH3 NH3 PbI3-x Xx ) by means of a vapor-assisted solution method at ambient atmosphere is reported. The perovskite films are synthesized by exposing PbI2 film to CH3 NH3 X (X=I, Br, or Cl) vapor. The prepared perovskite films have uniform surfaces with good coverage, as confirmed by SEM images. The inclusion of chlorine and bromine into the structure leads to a lower temperature and shorter reaction time for optimum perovskite film formation. In the case of CH3 NH3 PbI3-x Clx , the optimum reaction temperature is reduced to 100 °C, and the resulting phases are CH3 NH3 PbI3 (with trace Cl) and CH3 NH3 PbCl3 with a ratio of about 2:1. In the case of CH3 NH3 PbI3-x Brx , single-phase CH3 NH3 PbI2 Br is formed in a considerably shorter reaction time than that of CH3 NH3 PbI3 . The mesostructured perovskite solar cells based on CH3 NH3 PbI3 films show the best optimal power conversion efficiency of 13.5 %, whereas for CH3 NH3 PbI3-x Clx and CH3 NH3 PbI3-x Brx the best recorded efficiencies are 11.6 and 10.5 %, respectively.

  17. 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.

  18. Inhibition of mineralization of glutaraldehyde-pretreated bovine pericardium by AlCl3. Mechanisms and comparisons with FeCl3, LaCl3, and Ga(NO3)3 in rat subdermal model studies.

    PubMed

    Webb, C L; Schoen, F J; Flowers, W E; Alfrey, A C; Horton, C; Levy, R J

    1991-04-01

    In the present study, the authors investigated the mechanism by which Al3+ preincubations inhibited the pathologic calcification of glutaraldehyde-pretreated bovine pericardium (GPBP) implanted subdermally in rats. The concentration dependency of the Al3+ anticalcification effect was compared with that of other trivalent metal ions (Fe3+, Ga3+, La3+) known to interact with calcium phosphates. In vitro incubations of GPBP were carried out in AlCl3 (10(-3) mol/l [molar] to 10(-1) mol/l) to ascertain both the optimal conditions for uptake of Al3+ and the time course of Al3+ dissociation. Al3+ uptake by GPBP was concentration dependent and occurred rapidly, with tissue levels after 1 hour not differing significantly from those after 72 hours of incubation. Analyses of GPBP samples preincubated in AlCl3 (0.1 mol/l, 24 hours) showed that more than 75% of the Al3+ remained tightly bound after 60 days' in vitro release at 37 degrees C, pH 7.4. Preincubations of GPBP in AlCl3 significantly inhibited calcification after subdermal implantation in rats for 60 days (Ca++ = 5.1 +/- 0.9 microgram/mg, 11.5 +/- 4.6 micrograms/mg, 70.3 +/- 23.0 micrograms/mg, mean +/- standard error [SE], for 10(-1) mol/l, 10(-2) mol/l, 10(-3) mol/l AlCl3, respectively), compared with controls (Ca++ = 110.0 +/- 9.3 micrograms/mg). All animals were free of Al3(+)-mediated adverse effects on bone, as determined by light microscopic evaluation of femoral epiphyseal growth plates. Transmission electron microscopy coupled with electron energy loss spectroscopy (EELS) of GPBP incubated in 10(-1) mol l AlCl3 for 24 hours demonstrated discrete Al3+ localization in the sarcolemma and cytoplasmic and nuclear membranes of devitalized pericardial connective tissue cells at intracellular sites coincident with phosphorus loci. Similar intracellular localization remained prominent in explants removed after 60 days; no calcific deposits were noted in these specimens. Preincubations in Fe3+ but not Ga3+ and La3

  19. Chemical control of electrical properties and phase diagram of a series of {lambda}-type BETS superconductors, {lambda}-(BETS){sub 2}GaBr{sub x}Cl{sub 4{minus}x}

    SciTech Connect

    Tanaka, Hisashi; Kobayashi, Akiko; Sato, Akane; Akutsu, Hiroki; Kobayashi, Hayao

    1999-02-03

    {lambda}-(BETS){sub 2}GaBr{sub x}Cl{sub 4{minus}x} [BETS = bis(ethylenedithio)tetraselenafulvalene; 0 {le} x {le} 2] is a molecular superconductor with strongly correlated conduction electrons. The electrical transport properties of {lambda}-(BETS){sub 2}GaBr{sub x}-Cl{sub 4{minus}x} are drastically changed by varying the bromine content x or by applying pressure. At ambient pressure, the superconducting transition could be observed for x < 0.75. The pressure and x dependencies of {Tc} were examined. The M-H curve (M = magnetization; H = magnetic field) at 2 K indicated the almost perfect Meissner state of the superconducting phase of {lambda}-(BETS){sub 2}GaCl{sub 4}. The H{sub c1} is {approximately} 8 Oe for H{perpendicular} and 12 Oe for H{parallel}, where H{perpendicular} and H{parallel} are the magnetic fields perpendicular and parallel to the c axis, respectively. The magnetic susceptibility of {lambda}-(BETS){sub 2}GaBr{sub x}Cl{sub 4{minus}x} increases with decreasing temperature to {approximately} 60 K, below which the susceptibility becomes x-dependent and tends to be suppressed with increasing x. The isotropic decrease of the static susceptibility at lower temperature observed in the insulating system with x > 1.0 indicates the insulating ground state seems not to be suppressed with increasing x. The isotropic decrease of the static susceptibility at lower temperature observed in the insulating system with x > 1.0 indicates the insulating ground state seems not to be antiferromagnetic but probably nonmagnetic. The crystal structure determinations of a series of {lambda}-(BETS){sub 2}GaBr{sub x}Cl{sub 4{minus}x} and the calculations of the intermolecular overlap integrals of the highest occupied molecular orbital of BETS were made to elucidate a key factor of the superconducting transition mechanism. The x-dependence of intermolecular overlap integrals seems to suggest that the magnitude of the spin gap of the nonmagnetic insulating state tends to be

  20. 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

  1. 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

    NASA Astrophysics Data System (ADS)

    Katz, Brian G.; Eberts, Sandra M.; Kauffman, Leon J.

    2011-02-01

    SummaryA 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 (<20 m depth below land surface) had a significantly ( p < 0.05) higher median percentage of houses with septic tanks (1990 census data) than non-targeted wells. Higher ( p = 0.08) median nitrate-N concentration (3.1 mg/L) in oxic (dissolved oxygen concentrations >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

  2. 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

  3. Tin(IV) halide complexes of AsPh3) The structures of trans-SnCl4(AsPh3)2 and SnBr4(AsPh3).AsPh3.

    PubMed

    Mahon, Mary F; Moldovan, Natalia L; Molloy, Kieran C; Muresan, Alexandra; Silaghi-Dumitrescu, Ioan; Silaghi-Dumitrescu, Luminita

    2004-12-01

    The structures of two 1 : 2 adducts between tin(IV) halides and AsPh(3) have been determined. SnCl(4)(AsPh(3))(2) adopts a six-coordinate geometry at tin in which the two organoarsine donors are mutually trans. In contrast, SnBr(4)(AsPh(3))(2) is five-coordinate at tin and only one arsine is directly bonded to the metal, in an axial site of the trigonal bipyramid. The second AsPh(3) group has a close contact with the axially bound bromine [As...Br: 3.567(3) angstroms], which is a unique structural variation that depicts an intermediate in a halogen-transfer reaction between Group 14 and Group 15 elements. AACVD using SnCl(4)(AsPh(3))(2) generates a film containing SnO(2) and a second crystalline material which is possibly SnCl(2), but which contains no arsenic. PMID:15558128

  4. 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.

  5. 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. PMID:27124373

  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. 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.

  8. Theoretical investigation of the addition reaction of the aluminum chlorosilylenoid H2SiAlCl3 with ethylene.

    PubMed

    Zhang, Mingxia; Li, Wenzuo; Liu, Zhenbo; Li, Qingzhong; Cheng, Jianbo

    2016-07-01

    The addition reaction of the aluminum chlorosilylenoid H2SiAlCl3 with ethylene was investigated using the M06-2X and QCISD methods for the first time. The calculated results demonstrate that the addition reaction proceeds via two pathways: path I involves just one transition state, while path II involves two transition states. Path I is more feasible dynamically, as it has a lower barrier height than path II. The effect of the solvent CH2Cl2 was taken into consideration using the PCM model. The results indicated that the addition reaction is less likely to occur in CH2Cl2 solvent than in vacuum. This work has therefore highlighted a new pathway for the synthesis of silicon heterocyclic compounds. Graphical Abstract Relative energies (in kJ·mol(-1)) of the stationary points along the potential energy surfaces of the addition reaction of H2SiAlCl3 with C2H4 (values in parentheses were calculated in CH2Cl2 solvent). PMID:27271163

  9. Electron spin resonance studies on the organic linear-chain compounds (TMTCF)2X (C=S,Se X=PF6,AsF6,ClO4,Br)

    NASA Astrophysics Data System (ADS)

    Dumm, M.; Loidl, A.; Fravel, B. W.; Starkey, K. P.; Montgomery, L. K.; Dressel, M.

    2000-01-01

    We have conducted comprehensive electron spin resonance (ESR) investigations on single crystals of the one-dimensional organic compounds (TMTTF)2PF6, (TMTTF)2ClO4, (TMTTF)2Br, (TMTSF)2PF6, and (TMTSF)2AsF6 in the temperature range from 4 to 500 K and additionally, (TMTSF)2ReO4 and (TMTSF)2ClO4 at room temperature. In contrast to the selenium analogs TMTSF which are one-dimensional metals, the sulfur salts are semiconductors with localized spins on the TMTTF dimers. Taking into account the thermal expansion of the crystals at high temperature (T>20 K) the ESR intensity of all sulfur compounds can be described as a spin-1/2 antiferromagnetic Heisenberg chain with exchange constants 420<=J<=500 K. Although the TMTSF compounds are one-dimensional organic metals down to 10 K, the temperature dependence of the spin susceptibility can also be described within the framework of the Hubbard model in the limit of strong Coulomb repulsion with J~1400 K. By modeling (TMTTF)2ClO4 as an alternating spin chain, the change of the alternation parameter at the first-order phase transition (TAO=72.5 K) indicates a tetramerization of the chain. (TMTTF)2PF6 undergoes a spin-Peierls transition at TSP=19 K which can be well described by Bulaevskii's model with a singlet-triplet gap Δσ(0)=32.3 K. We find evidence of antiferromagnetic fluctuations at temperatures well above the magnetic ordering in (TMTTF)2Br, (TMTSF)2PF6, and (TMTSF)2AsF6 which follow the critical behavior expected for three-dimensional ordering. (TMTTF)2PF6 and (TMTTF)2Br show one-dimensional lattice fluctuations.

  10. 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.

  11. 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’.

  12. 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

    2014-01-01

    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.

  13. Shubnikov-de Haas oscillations in a new dual-layered quasi-two-dimensional organic metal (BETS)4CoBr4(C6H4Cl2)

    NASA Astrophysics Data System (ADS)

    Lyubovskii, R. B.; Pesotskii, S. I.; Shilov, G. V.; Zhilyaeva, E. I.; Flakina, A. M.; Lyubovskaya, R. N.

    2013-10-01

    The interlayer and intralayer resistances and Shubnikov-de Haas oscillations in a new dual-layered quasi-two-dimensional organic metal (BETS)4CoBr4(C6H4Cl2) with a periodically varying structure of cation layers have been studied. It has been shown that the interlayer resistivity corresponds to an incoherent or weakly incoherent transport regime. The oscillations of the magnetoresistance have been described by a model of a chain of coherent magnetic breakdown orbits taking into account the quantum interference effect. The behavior of the interlayer transport, as well as quantum oscillations, is in good agreement with the theoretical calculations of the band structure.

  14. Magnitude and origin of the attraction and directionality of the halogen bonds of the complexes of C6F5X and C6H5X (X = I, Br, Cl and F) with pyridine.

    PubMed

    Tsuzuki, Seiji; Wakisaka, Akihiro; Ono, Taizo; Sonoda, Takaaki

    2012-01-16

    The geometries and interaction energies of complexes of pyridine with C(6)F(5)X, C(6)H(5)X (X = I, Br, Cl, F and H) and R(F)I (R(F) = CF(3), C(2)F(5) and C(3)F(7)) have been studied by ab initio molecular orbital calculations. The CCSD(T) interaction energies (E(int)) for the C(6)F(5)X-pyridine (X = I, Br, Cl, F and H) complexes at the basis set limit were estimated to be -5.59, -4.06, -2.78, -0.19 and -4.37 kcal  mol(-1) , respectively, whereas the E(int) values for the C(6)H(5)X-pyridine (X = I, Br, Cl and H) complexes were estimated to be -3.27, -2.17, -1.23 and -1.78 kcal  mol(-1), respectively. Electrostatic interactions are the cause of the halogen dependence of the interaction energies and the enhancement of the attraction by the fluorine atoms in C(6)F(5)X. The values of E(int) estimated for the R(F)I-pyridine (R(F) = CF(3), C(2)F(5) and C(3)F(7)) complexes (-5.14, -5.38 and -5.44 kcal  mol(-1), respectively) are close to that for the C(6)F(5)I-pyridine complex. Electrostatic interactions are the major source of the attraction in the strong halogen bond although induction and dispersion interactions also contribute to the attraction. Short-range (charge-transfer) interactions do not contribute significantly to the attraction. The magnitude of the directionality of the halogen bond correlates with the magnitude of the attraction. Electrostatic interactions are mainly responsible for the directionality of the halogen bond. The directionality of halogen bonds involving iodine and bromine is high, whereas that of chlorine is low and that of fluorine is negligible. The directionality of the halogen bonds in the C(6)F(5)I- and C(2)F(5)I-pyridine complexes is higher than that in the hydrogen bonds in the water dimer and water-formaldehyde complex. The calculations suggest that the C-I and C-Br halogen bonds play an important role in controlling the structures of molecular assemblies, that the C-Cl bonds play a less important role and that C-F bonds

  15. Competition of C(sp²)-X···O halogen bonding and lone pair···π interactions: cryospectroscopic study of the complexes of C₂F₃X (X = F, Cl, Br, and I) and dimethyl ether.

    PubMed

    Geboes, Yannick; Nagels, Nick; Pinter, Balazs; De Proft, Frank; Herrebout, Wouter A

    2015-03-19

    Inspection of the electrostatic potential of C2F3X (X = F, Cl, Br, and I) revealed a second electropositive region in the immediate vicinity of the C═C double bond apart from the σ hole of chlorine, bromine, and iodine, leading to C(sp(2))-X···Y halogen bonding, through which complexes stabilized by so-called lone pair···π interactions can be formed. Consequently, the experimental studies for the complexes of dimethyl ether with C2F3X (X = F, Cl, Br, and I) not only allowed one to experimentally characterize and rationalize the effects of hybridization on halogen bonding but, for the first time, also allowed the competition of C-X···Y halogen bonding and lone pair···π interactions to be studied at thermodynamic equilibrium. Analysis of the infrared and Raman spectra reveals that in the cryosolutions of dimethyl ether and C2F3I, solely the halogen-bonded complex is present, whereas C2F3Br and C2F3Cl give rise to a lone pair···π bonded complex as well as a halogen-bonded complex. Mixtures of dimethyl ether with C2F4 solely yield a lone pair···π bonded complex. The experimentally derived complexation enthalpies for the halogen bonded complexes are found to be -14.2(5) kJ mol(-1) for C2F3I·DME and -9.3(5) kJ mol(-1) for C2F3Br·DME. For the complexes of C2F3Cl with dimethyl ether, no experimental complexation enthalpy could be obtained, whereas the C2F4·DME complex has a complexation enthalpy of -5.5(3) kJ mol(-1). The observed trends have been rationalized with the aid of an interaction energy decomposition analysis (EDA) coupled to a Natural Orbital for Chemical Valence (NOCV) analysis and also using the noncovalent interaction index method.

  16. 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

    2016-04-01

    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.

  17. Aluminum fluxing salts: a critical review of the chemistry and structures of alkali aluminum halides. Information circular/1986. [System NaCl-KCl-AlCl/sub 3/-NaF-KF-AlF/sub 3/

    SciTech Connect

    Sorrell, C.A.; Groetsch, J.G.; Soboroff, D.M.

    1986-01-01

    The publication reviews the structural characteristics of crystalline phases and phase equilibria data for the system NaCl-KCl-AlCl/sub 3/-NaF-KF-AlF/sub 3/, which encompasses a large number of molten salt fluxes currently used in aluminum recycling. Its purpose is to provide guidelines for research into the relationships between molten salt compositions and their physical properties, notably vapor pressures, densities, surface tensions, and viscosities, knowledge of which is essential to minimizing fluxing efficiencies and metal recovery and minimizing hazardous emissions and disposal problems. In addition, the report describes experimental determinations of sub-solidus compatibility relationships in the system, which is of the quaternary reciprocal type, containing 12 different stable 4-phase assemblages in the solid state. The compatibility diagram serves to define the important compositional planes across which important changes in properties are likely to occur.

  18. Comparison of the dynamics of the reactions of Ba with aromatic halides and alkyl halides LIF studies of the reactions of Ba with C 6H 5X (X  Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Han, Ke-Li; He, Guo-Zhong; Lou, Nan-Quan

    1993-03-01

    Nascent internal state energy distributions of BaX have been studied for the reactions Ba + C 6H 5X→BaX+C 6H 5 (X  Cl, Br, 1) using the laser-induced fluorescence method in a beam-gas arrangement. The energy disposal differs markedly from that of the reactions Ba + CH 3X. With the change of X from Cl to I, the vibrational excitations and the reactive cross sections decrease for the reactions Ba + C 6H 5X, whereas those of the reactions Ba + CH 3X increase. The CNDO/2 calculations of C 6H 5X and CH 3X have been used to interpret the experimental results qualitatively.

  19. Comparative density functional theory and post-Hartree-Fock (CCSD, CASSCF) studies on the electronic structure of halogen nitrites ClONO and BrONO using quantum chemical topology.

    PubMed

    Berski, Slawomir; Gordon, Agnieszka J

    2011-09-01

    In this paper, the electronic structures of cis- and trans-ClONO and BrONO are studied at the CCSD∕aug-cc-pVTZ, CASSCF(14,12)/aug-cc-pVTZ, and B3LYP/aug-cc-pVTZ computational levels. For the Cl-O bond, topological analysis of the electron density field, ρ(r), shows the prevalence of the shared-electron type bond (∇(2)ρ((3,-1)) < 0). The Br-O bond, however, represents the closed-shell interaction (∇(2)ρ((3,-1)) > 0). Topological analysis of the electron localization function, η(r), and electron localizability indicator (ELI-D), (D) (σ)(r), shows that the electronic structure of the central N-O bond is very sensitive to both electron correlation improvements (coupled-cluster single double (CCSD), CASSCF, density functional theory (DFT)) and bond length alteration. Depending on the method used, the N-O bond can be characterized as a "normal" N-O bond with a disynaptic V(N,O) basin (DFT); a protocovalent N-O bond with two monosynaptic, V(N) and V(O), basins (CCSD, CASSCF); or a new type, first discovered for FONO, characterized by a single monosynaptic, V(N) basin (CCSD, DFT). The total basin population oscillates between 0.46-0.96 e (CCSD) and 0.86-1.02 e (CASSCF). The X-O bond is described by the single disynaptic basin, V(X,O), with a basin population between 0.76 and 0.81 e (CCSD) or 0.77 and 0.85 e (CASSCF). Analysis of the localized electron detector distribution for the cis-Cl-O1-N=O2 shows a manifold in the Cl···O2 region, associated with decreased electron density.

  20. Conversion of glucose into furans in the presence of AlCl3 in an ethanol-water solvent system.

    PubMed

    Yang, Yu; Hu, Changwei; Abu-Omar, Mahdi M

    2012-07-01

    Glucose was converted into furans (5-hydroxymethylfurfural and 5-ethoxymethylfurfural) in the presence of AlCl(3) in an ethanol-water solvent system. The system showed high activity for the conversion of glucose into furans but low activity for the subsequent formation of LAs (levulinic acid and ethyl levulinate). High furans yield of 57% with low LAs yield of 11% can be obtained at 160 °C within 15 min. Glucose-based disaccharides (sucrose, maltose and cellobiose) and polysaccharides (starch but not cellulose) can also be converted to furans effectively under the same condition. AlCl(3) can be used to prepare furans from biomass-derived compounds in ethanol-water, a green solvent system. PMID:22609675

  1. 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.

  2. Transmission Line Modeling Applied to Hot Corrosion of Fe-40at.pctAl in Molten LiCl-KCl

    NASA Astrophysics Data System (ADS)

    Barraza-Fierro, Jesus Israel; Espinosa-Medina, Marco Antonio; Castaneda, Homero

    2015-12-01

    The effect of Cu and Li additions to the intermetallic alloy Fe-40at.pctAl on the corrosion performance in an LiCl-55wtpctKCl molten eutectic salt was studied by means of electrochemical impedance spectroscopy, transmission line modeling (TLM), and cathodic polarization. The tests were done at 723 K, 773 K, and 823 K (450 °C, 500 °C, and 550 °C), for 60 and 720 minutes. The element additions could improve the corrosion resistance of Fe-40at.pctAl in molten LiCl-KCl, while TLM could characterize and quantify the interfacial processes in hot corrosion. The polarization curves helped to establish the possible cathodic reactions in the experimental conditions.

  3. Cl{sub 2}-based dry etching of the AlGaInN system in inductively coupled plasmas

    SciTech Connect

    Cho, Hyun; Vartuli, C.B.; Abernathy, C.R.; Donovan, S.M.; Pearton, S.J.; Shul, R.J.; Han, J.

    1997-12-01

    Cl{sub 2}-based Inductively Coupled Plasmas with low additional dc self- biases(-100V) produce convenient etch rates(500-1500 A /min) for GaN, AlN, InN, InAlN and InGaN. A systematic study of the effects of additive gas(Ar, N{sub 2}, H{sub 2}), discharge composition and ICP source power and chuck power on etch rate and surface morphology has been performed. The general trends are to go through a maximum in etch rate with percent Cl{sub 2} in the discharge for all three mixtures, and to have an increase(decrease) in etch rate with source power(pressure). Since the etching is strongly ion-assisted, anisotropic pattern transfer is readily achieved. Maximum etch selectivities of approximately 6 for InN over the other nitrides were obtained.

  4. AlCl3-Catalyzed Ring-Expansion Cascades of Bicyclic Cyclobutenamides Involving Highly Strained Cis,Trans-Cycloheptadienone Intermediates

    PubMed Central

    Wang, Xiao-Na; Krenske, Elizabeth H.; Johnston, Ryne C.; Houk, K. N.; Hsung, Richard P.

    2015-01-01

    We report the first experimental evidence for the generation of highly strained cis,trans-cycloheptadienones by electrocyclic ring opening of 4,5-fused cyclobutenamides. In the presence of AlCl3, the cyclobutenamides rearrange to [2.2.1]-bicyclic ketones; DFT calculations provide evidence for a mechanism involving torquoselective 4π-electrocyclic ring opening to a cis,trans-cycloheptadienone followed by a Nazarov-like recyclization and a 1,2-alkyl shift. Similarly, 4,6-fused cyclobutenamides undergo AlCl3-catalyzed rearrangements to [3.2.1]-bicyclic ketones through cis,trans-cyclooctadienone intermediates. The products can be further elaborated via facile cascade reactions to give complex tri- and tetracyclic molecules. PMID:25895058

  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. 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.

  7. 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

    2015-11-01

    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%.

  8. Communication: probing the entrance channels of the X+CH4→HX+CH3 (X = F, Cl, Br, I) reactions via photodetachment of X(-)-CH4.

    PubMed

    Cheng, Min; Feng, Yuan; Du, Yikui; Zhu, Qihe; Zheng, Weijun; Czakó, Gábor; Bowman, Joel M

    2011-05-21

    The entrance channel potentials of the prototypical polyatomic reaction family X + CH(4) → HX + CH(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(-)-CH(4) anion complex. For F-CH(4), a spin-orbit splitting (∼1310 cm(-1)) much larger than that of the F atom (404 cm(-1)) was observed, in good agreement with theory. This showed that in the case of the F-CH(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(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.

  9. Heterometallic aggregates of copper(I) with metalloligand Sn(edt)2 (edt = ethane-1,2-dithiolate): syntheses and structures of [Sn(edt)2Cl(mu-I)(mu3-I)(CuPPh3)3], [Sn(edt)2(mu-Br)2(mu3-Br)2(CuPPh3)4], and [{Sn(edt)2}3(mu-OH)3Cu5(PPh3)8][PF6]2.

    PubMed

    Han, Yan-Gong; Xu, Chao; Duan, Taike; Wu, Fang-Hui; Zhang, Qian-Feng; Leung, Wa-Hung

    2009-09-21

    The treatment of a slurry of an equimolar mixture of [Sn(edt)(2)] (edt = ethane-1,2- dithiolate) and [Et(4)N]Cl.xH(2)O with CuI in the presence of PPh(3) gave a tetranuclear compound, [Sn(edt)(2)Cl(mu-I)(mu(3)-I)(CuPPh(3))(3)] (1), which consists of a rectangular-pyramidal [Sn(edt)(2)Cl](-) moiety ligated by three [Cu(PPh(3))](+) fragments via the sulfur atoms of the edt(2-) ligands. The treatment of a slurry of [Sn(edt)(2)] and excess [Et(4)N]Br with [Cu(MeCN)(4)][PF(6)] in the presence of PPh(3) afforded a pentanuclear compound, [Sn(edt)(2)(mu-Br)(2)(mu(3)-Br)(2)(CuPPh(3))(4)] (2), which comprises two [(CuPPh(3))(2)(mu-Br)](+) fragments symmetrically ligating an octahedral trans-[Sn(edt)(2)Br(2)](2-) moiety via the sulfur and bromide atoms. Reaction of [Sn(edt)(2)] with [Cu(MeCN)(4)][PF(6)] and PPh(3) in a mixed MeCN/CH(2)Cl(2) solution yielded a novel octanuclear compound, [{Sn(edt)(2)}(3)(mu-OH)(3)Cu(5)(PPh(3))(8)][PF(6)](2) (3), which may be described as a triangular [{Sn(edt)(2)}(3)(mu-OH)(3)](3-) core chelated by three [Cu(PPh(3))(2)](+) species and capped by two [Cu(PPh(3))](+) species. The luminescent properties of compounds 1, 2, and 3 were investigated in a CH(2)Cl(2) solution at room temperature. Upon excitation at lambda > 360 nm, these compounds are luminescent in CH(2)Cl(2) solution with emissions having maxima at 422, 515, and 494 nm, respectively. PMID:19746999

  10. Laser-excited fluorescence and electron-spin resonance of Er3+ in polycrystalline AlCl3

    NASA Astrophysics Data System (ADS)

    Ceotto, G.; Pires, M. A.; Sanjurjo, J. A.; Rettori, C.; Barberis, G. E.

    1990-07-01

    The green fluorescence transitions among the levels corresponding to the 4S3/2 and 4I15/2 configurations of Er3+ diluted in AlCl3 have been measured using laser excitation. The data allow us to determine the crystalline-field splittings of these levels and, in turn, the spin-Hamiltonian parameters. The electron-paramagnetic-resonance spectrum observed at low temperatures is in good agreement with that expected from these parameters.

  11. Preparation and Electrochemical Characterization of Aluminium Liquid Battery Cells With Two Different Electrolytes (NaCl-BaCl2-AlF3-NaF and LiF-AlF3-BaF2).

    PubMed

    Napast, Viktor; Moškon, Jože; Homšak, Marko; Petek, Aljana; Gaberšček, Miran

    2015-01-01

    The possibility of preparation of operating rechargeable liquid battery cells based on aluminium and its alloys is systematically checked. In all cases we started from aluminium as the negative electrode whereas as the positive electrode three different metals were tested: Pb, Bi and Sn. Two types of electrolytes were selected: Na(3)AlF(6) -AlF(3) - BaCl(2) - NaCl and Li(3)AlF(3) - BaF(2). We show that some of these combinations allowed efficient separation of individual liquid layers. The cells exhibited expected voltages, relatively high current densities and could be charged and discharged several times. The capacities were relatively low (120 mAh in the case of Al-Pb system), mostly due to unoptimised cell construction. Improvements in various directions are possible, especially by hermetically sealing the cells thus preventing salt evaporation. Similarly, solubility of aluminium in alloys can be increased by optimising the composition of positive electrode. PMID:26680707

  12. Preparation and Electrochemical Characterization of Aluminium Liquid Battery Cells With Two Different Electrolytes (NaCl-BaCl2-AlF3-NaF and LiF-AlF3-BaF2).

    PubMed

    Napast, Viktor; Moškon, Jože; Homšak, Marko; Petek, Aljana; Gaberšček, Miran

    2015-01-01

    The possibility of preparation of operating rechargeable liquid battery cells based on aluminium and its alloys is systematically checked. In all cases we started from aluminium as the negative electrode whereas as the positive electrode three different metals were tested: Pb, Bi and Sn. Two types of electrolytes were selected: Na(3)AlF(6) -AlF(3) - BaCl(2) - NaCl and Li(3)AlF(3) - BaF(2). We show that some of these combinations allowed efficient separation of individual liquid layers. The cells exhibited expected voltages, relatively high current densities and could be charged and discharged several times. The capacities were relatively low (120 mAh in the case of Al-Pb system), mostly due to unoptimised cell construction. Improvements in various directions are possible, especially by hermetically sealing the cells thus preventing salt evaporation. Similarly, solubility of aluminium in alloys can be increased by optimising the composition of positive electrode.

  13. A cryospectroscopic infrared and Raman study of the CX⋯π halogen bonding motif: complexes of the CF3Cl, CF3Br, and CF3I with ethyne, propyne and 2-butyne.

    PubMed

    Nagels, Nick; Herrebout, Wouter A

    2015-02-01

    Experimental information on the C-X⋯π halogen bonding motif was obtained by studying the formation of molecular complexes of CF3Cl, CF3Br and CF3I with ethyne, propyne and 2-butyne in liquid krypton, using FTIR and Raman spectroscopy. For CF3Br, experimental evidence was found for the formation of 1:1 complexes with propyne and 2-butyne only, while for CF3I spectroscopic features confirming the existence of the halogen bonded complexes were observed for ethyne, propyne and 2-butyne. In addition, at higher concentrations of CF3I and 2-butyne, weak absorptions due to a 2:1 complex were also observed. The experimental complexation enthalpies, obtained by using spectra recorded at temperatures between 120 K and 140 K, are -5.9(3) kJ mol(-1) for CF3I.ethyne, -5.6(3) kJ mol(-1) for CF3Br.propyne, -8.1(2) kJ mol(-1) for CF3I.propyne, -7.3(2) kJ mol(-1) for CF3Br.2-butyne, -10.9(2) kJ mol(-1) for CF3I.2-butyne and -20.9(7) kJ mol(-1) for (CF3I)2.2-butyne. The experimental study is supported by theoretical data obtained from ab initio calculations at the MP2/aug-cc-pVDZ(-PP) and MP2/aug-cc-pVTZ(-PP) levels, and Monte Carlo Free Energy Perturbation (MC-FEP) simulations. The experimental and theoretical values on the C-X⋯π halogen-bonding motifs studied are compared with previously reported data for the complexes with ethene and propene and with preliminary results obtained for benzene and toluene.

  14. A cryospectroscopic infrared and Raman study of the CX⋯π halogen bonding motif: complexes of the CF3Cl, CF3Br, and CF3I with ethyne, propyne and 2-butyne.

    PubMed

    Nagels, Nick; Herrebout, Wouter A

    2015-02-01

    Experimental information on the C-X⋯π halogen bonding motif was obtained by studying the formation of molecular complexes of CF3Cl, CF3Br and CF3I with ethyne, propyne and 2-butyne in liquid krypton, using FTIR and Raman spectroscopy. For CF3Br, experimental evidence was found for the formation of 1:1 complexes with propyne and 2-butyne only, while for CF3I spectroscopic features confirming the existence of the halogen bonded complexes were observed for ethyne, propyne and 2-butyne. In addition, at higher concentrations of CF3I and 2-butyne, weak absorptions due to a 2:1 complex were also observed. The experimental complexation enthalpies, obtained by using spectra recorded at temperatures between 120 K and 140 K, are -5.9(3) kJ mol(-1) for CF3I.ethyne, -5.6(3) kJ mol(-1) for CF3Br.propyne, -8.1(2) kJ mol(-1) for CF3I.propyne, -7.3(2) kJ mol(-1) for CF3Br.2-butyne, -10.9(2) kJ mol(-1) for CF3I.2-butyne and -20.9(7) kJ mol(-1) for (CF3I)2.2-butyne. The experimental study is supported by theoretical data obtained from ab initio calculations at the MP2/aug-cc-pVDZ(-PP) and MP2/aug-cc-pVTZ(-PP) levels, and Monte Carlo Free Energy Perturbation (MC-FEP) simulations. The experimental and theoretical values on the C-X⋯π halogen-bonding motifs studied are compared with previously reported data for the complexes with ethene and propene and with preliminary results obtained for benzene and toluene. PMID:24910010

  15. High temperature infrared spectra of dimeric and monomeric AlBr 3, AlI 3 and GaCl 3 in the vapour phase

    NASA Astrophysics Data System (ADS)

    Sjøgren, C. E.; Klaeboe, P.; Rytter, E.

    The i.r. spectra of aluminium bromide, aluminium iodide and gallium chloride vapours were measured in the region 50-700 cm -1 with an evacuable Fourier transform spectrometer by transmission and emission techniques. Evacuable cells of nickel were employed having windows of type IIa diamond and sealed with o-rings of gold. The dimer spectra were interpreted in terms of D2 h symmetry and seven of the eight i.r. active fundamentals were assigned. The monomer spectra were interpreted in terms of D3 h symmetry and the three i.r. active fundamentals were assigned. Valence force fields were derived for the three dimers and three monomers based upon the present i.r. frequencies and on Raman data reported previously.

  16. 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.

  17. 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.

  18. Six- and eight-coordinate thio- and seleno-ether complexes of NbF5 and some comparisons with NbCl5 and NbBr5 adducts.

    PubMed

    Jura, Marek; Levason, William; Ratnani, Raju; Reid, Gillian; Webster, Michael

    2010-01-21

    The reaction of RS(CH(2))(2)SR (R = Me, Et or (i)Pr) with NbF(5) produces [NbF(4){RS(CH(2))(2)SR}(2)][NbF(6)] which contain distorted eight-coordinate (dodecahedral) cations and octahedral anions, whereas RSe(CH(2))(2)SeR (R = Me or Bu(n)) form six-coordinate [(NbF(5))(2)(mu-RSe(CH(2))(2)SeR)]. Et(2)S and Me(2)Se (L) also form six-coordinate [NbF(5)(L)], but Me(2)S forms both [NbF(5)(Me(2)S)] and an eight-coordinate cation in [NbF(4)(Me(2)S)(4)][NbF(6)]. MeS(CH(2))(2)SMe forms eight-coordinate cations in [NbX(4){MeS(CH(2))(2)SMe}(2)][NbX(6)] (X = Cl or Br), but other complexes of the heavier halides including [NbX(5)(L)] and [(NbX(5))(2)(mu-L-L)] (L-L = RSe(CH(2))(2)SeR; o-C(6)H(4)(CH(2)SMe)(2) and o-C(6)H(4)(CH(2)SeMe)(2)) contain six-coordinate niobium. The very unstable [NbCl(5)(Me(2)Te)] was characterised spectroscopically, but all other attempts to form telluroether complexes resulted in decomposition, and NbI(5) was reduced even by thioethers. The complexes have been characterised by multinuclear NMR ((1)H, (19)F, (93)Nb, (77)Se or (125)Te), IR and UV/visible spectroscopy, and X-ray crystal structures are reported for [NbF(4){RS(CH(2))(2)SR}(2)][NbF(6)] (R = Me, (i)Pr), [NbF(4)(Me(2)S)(4)][NbF(6)], [NbCl(5)(Me(2)Se)], [NbBr(5)(Me(2)S)], [(NbCl(5))(2){o-C(6)H(4)(CH(2)SMe)(2)}] and [(NbCl(5))(2){MeSe(CH(2))(2)SeMe}]. All the complexes are very moisture sensitive and the fluoride complexes decompose slowly with fluorination of the neutral ligand. PMID:20066233

  19. Fine Structures of 8-G-1-(p-YC6H4C ≡ CSe)C10H6 (G = H, Cl, and Br) in Crystals and Solutions: Ethynyl Influence and Y- and G-Dependences

    PubMed Central

    Hayashi, Satoko; Yamane, Kentaro; Nakanishi, Waro

    2009-01-01

    Fine structures of 8-G-1-(p-YC6H4C ≡ CSe)C10H6 [1 (G = H) and 2 (G = Cl): Y = H (a), OMe (b), Me (c), F (d), Cl (e), CN (f), and NO2 (g)] are determined by the X-ray analysis. Structures of 1, 2, and 3 (G = Br) are called A if each Se–Csp bond is perpendicular to the naphthyl plane, whereas they are B when the bond is placed on the plane. Structures are observed as A for 1a–c bearing Y of nonacceptors, whereas they are B for 1e–g with Y of strong acceptors. The change in the structures of 1e–g versus those of 1a–c is called Y-dependence in 1. The Y-dependence is very specific in 1 relative to 1-(p-YC6H4Se)C10H7 (4) due to the ethynyl group: the Y-dependence in 1 is almost inverse to the case of 4 due to the ethynyl group. We call the specific effect “Ethynyl Influence.” Structures of 2 are observed as B: the A-type structure of 1b changes dramatically to B of 2b by G = Cl at the 8-position, which is called G-dependence. The structures of 2 and 3 are examined in solutions based on the NMR parameters. PMID:19809512

  20. The motley family of polar compounds (MV)[M(X{sub 5-x}X Prime {sub x})] based on anionic chains of trans-connected M{sup (III)}(X,X Prime ){sub 6} octahedra (M=Bi, Sb; X, X Prime =Cl, Br, I) and methylviologen (MV) dications

    SciTech Connect

    Leblanc, Nicolas; Mercier, Nicolas; Allain, Magali; Toma, Oksana; Auban-Senzier, Pascale; Pasquier, Claude

    2012-11-15

    The search for hybrid organic-inorganic materials remains a great challenge in the field of ferroelectrics. Following the discovery of the room temperature ferroelectric material (MV)[BiI{sub 3}Cl{sub 2}] (MV{sup 2+}: methylviologen) exhibiting the highest polarization value in the field of hybrid ferroelectrics, we report here nine new hybrids with the general formulation (MV)[M{sup (III)}X{sub 5-x}X Prime {sub x}] (M=Bi, Sb; X, X Prime =Cl, Br, I): (MV)[BiCl{sub 3.3}Br{sub 1.7}] (1), (MV)[BiCl{sub 1.3}Br{sub 3.7}] (2), (MV)[BiBr{sub 3.2}I{sub 1.8}] (3), (MV)[SbCl{sub 5}] (4), (MV)[SbBr{sub 5}] (5), (MV)[SbCl{sub 3.8}Br{sub 1.2}] (6), (MV)[SbCl{sub 2.4}Br{sub 2.6}] (7), (MV)[SbI{sub 3}Cl{sub 2}] (8) and (MV)[SbBr{sub 3.8}I{sub 1.2}] (9). Depending on the presence of polar chains or not, and on the coupling of polar chains, two types of centrosymmetrical structures [C1] and [C2] and two types of polar structures [P1] and [P2] are defined. (2) undergoes a paraelectric-to-relaxor ferroelectric transition around 100-150 K depending of the frequency showing that the Curie temperature, T{sub C}, of (MV)[BiBr{sub 5}] (243 K) can be modulated by the substitution of Br by Cl. The most interesting family is the [P2] type because the syn coupling of polar chains is in favor of high polarization values, as in (MV)[BiI{sub 3}Cl{sub 2}]. Five of the nine new hybrids, (4), (6-9), which have the [P2] type structure are potential ferroelectrics. - Graphical abstract: The methylviologen haloantimonate (MV)[SbX{sub 5-x}X Prime {sub x}] families (X, X Prime =Cl, Br, I) - [P1] and [P2] are the two kinds of polar structures - and view of the (MV)[SbBr{sub 3.8}I{sub 1.2}] hybrid based on chiral polar chains which are in syn coupling. Highlights: Black-Right-Pointing-Pointer Nine hybrids based on methylviologen and halometalate chains have been discovered. Black-Right-Pointing-Pointer The polar nature of chains is due to the ns{sup 2} stereoactivity of Sb{sup (III)} or Bi{sup (III

  1. 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.

  2. 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

    2009-06-01

    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.

  3. 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.

  4. 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.

  5. Pb6Ba2(BO3)5X (X = Cl, Br): new borate halides with strong predicted optical anisotropies derived from Pb(2+) and (BO3)(3.).

    PubMed

    Liu, Lu; Zhang, Bingbing; Zhang, Fangfang; Pan, Shilie; Zhang, Fangyuan; Zhang, Xingwen; Dong, Xiaoyu; Yang, Zhihua

    2015-04-21

    Two new borate halides, Pb6Ba2(BO3)5X (X = Cl, Br), have been synthesized by solid-state reactions and their structures determined by single-crystal X-ray diffraction. They are isostructural and feature 3D frameworks composed of alternate stacking of [PbBO] and [PbBOX] layers which are connected by 10-coordinated Ba atoms along the c direction. First-principles calculations show that both compounds have a large birefringence of 0.1582 and 0.1810 at 532 nm, respectively. The large birefringence originates from the strong optical anisotropies of the Pb(2+) cations and (BO3)(3-) groups based on the real-space atom-cutting analysis. The IR and UV-Vis-NIR diffuse reflectance spectroscopy, as well as thermal stability analyses of both compounds, were performed. PMID:25785911

  6. Understanding magnetic interactions in the series A2FeX5ṡH2O ( A=K , Rb; X=Cl , Br). II. Inelastic neutron scattering and DFT studies

    NASA Astrophysics Data System (ADS)

    Campo, Javier; Luzón, Javier; Palacio, Fernando; McIntyre, Garry J.; Millán, Angel; Wildes, Andrew R.

    2008-08-01

    The compounds A2FeX5ṡH2O ( A=alkali or NH4 , X=Cl , Br) form a series of easy-axis antiferromagnets with transition temperatures in the range from 6 to 23 K, temperatures considerably higher than those of other similar hydrated salts of transition-metal ions. A study combining inelastic triple axis neutron spectroscopy (TAS) neutron scattering experiments and theoretical density functional theory (DFT) ab initio calculations of the magnetic superexchange constants has been done. A general spin-wave theory for an antiferromagnetic system with several magnetic ions in the magnetic unit cell and both uniaxial and rhombic magnetic anisotropies was employed to fit the observed magnon dispersion curves. The results obtained with the two techniques (TAS and DFT) allow us to determine with accuracy the magnetic exchange constants and therefore explain the efficiency of the superexchange pathways containing hydrogen bonds in transmitting the magnetic interactions.

  7. Band Gaps of the Lead-Free Halide Double Perovskites Cs2BiAgCl6 and Cs2BiAgBr6 from Theory and Experiment.

    PubMed

    Filip, Marina R; Hillman, Samuel; Haghighirad, Amir Abbas; Snaith, Henry J; Giustino, Feliciano

    2016-07-01

    The recent discovery of lead-free halide double perovskites with band gaps in the visible represents an important step forward in the design of environmentally friendly perovskite solar cells. Within this new family of semiconductors, Cs2BiAgCl6 and Cs2BiAgBr6 are stable compounds crystallizing in the elpasolite structure. Following the recent computational discovery and experimental synthesis of these compounds, a detailed investigation of their electronic properties is warranted in order to establish their potential as optoelectronic materials. In this work, we perform many-body perturbation theory calculations and obtain high accuracy band gaps for both compounds. In addition, we report on the synthesis of Cs2BiAgBr6 single crystals, which are stable in ambient conditions. From our complementary theoretical and experimental analysis, we are able to assign the indirect character of the band gaps and obtain both experimental and theoretical band gaps of these novel semiconductors that are in close agreement. PMID:27322413

  8. Formation of gas-phase bromine from interaction of ozone with frozen and liquid NaCl/NaBr solutions: quantitative separation of surficial chemistry from bulk-phase reaction.

    PubMed

    Oldridge, N W; Abbatt, J P D

    2011-03-31

    The formation kinetics of gas-phase bromine (Br(2)) from interaction of gas-phase ozone (O(3)) with frozen and liquid solutions of NaCl (0.55 M) and NaBr (largely from 1.7 to 8.5 mM) have been studied from -40 to 0 °C in a coated-wall flow tube coupled to a chemical ionization mass spectrometer. The reactive uptake coefficient for O(3) is deduced from the product formation rate and then studied as a function of experimental conditions. In particular, for both the liquid and frozen solutions, we find that the uptake coefficient is inversely dependent on the gas-phase O(3) concentration in a manner that is quantitatively consistent with both surface- and bulk-phase kinetics. The reaction is fastest on acidic media (pH of the starting solution down to 2) but also proceeds at an appreciable rate on neutral substrates. Above 253 K, the uptake coefficient increases with increasing temperature on frozen solutions, consistent with an increasing brine content. The similarity of the absolute magnitude and form of the kinetics on the frozen and liquid substrates suggests that the reaction on the frozen solution is occurring with the associated brine, and not with the ice bulk or a quasi-liquid layer existing on the ice. The implications of these results to bromine activation in the tropospheric boundary layer are made.

  9. 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.

  10. Magnetic studies on hexahalorhenate(IV) salts of ferrocenium cations [Fe(C5R5)2]2[ReX6] (R = H, CH3; X = Cl, Br, I).

    PubMed

    González, Ricardo; Chiozzone, Raúl; Kremer, Carlos; Guerra, Francesca; De Munno, Giovanni; Lloret, Francesc; Julve, Miguel; Faus, Juan

    2004-05-01

    The hexahalorhenate(IV) salts of formula [Fe(C5H5)2]2[ReX6], with X = Cl (1), Br (2), and I (3), and [Fe(C5Me5)2]2[ReX6], with X = Cl (4), Br (5), and I (6) ([Fe(C5Me5)2]+ = decamethylferrocenium cation), have been synthesized and the structures of 1, 2, and 4 determined by single-crystal X-ray diffraction. 1, 2, and 4 crystallize in the orthorhombic system, space groups Pbca (1 and 2) and Ibam (4), with a = 14.099(2) A, b = 16.125(2) A, and c = 22.133(15) A, for 1, a = 14.317(3) A, b = 16.848(3) A, and c = 22.099(2) A for 2, and a = 15.8583(5) A, b = 15.9368(5) A, and c = 16.9816(6) A for 4. The three structures are made up of discrete [ReX6]2- anions and ferrocenium cations held together by electrostatic forces. There are anion-anion contacts in 1 and 2 but only through one direction. The [ReX6]2- octahedra are arranged along the y axis forming chains of Re and X atoms, -Re-X...X-Re-X...X-Re-, where the intermolecular X...X distances are shorter than the van der Waals distances. A somewhat greater separation between the anions occurs in 4. The magnetic properties of 1-6 were investigated in the temperature range 2.0-300 K. 1, 2, 4, and 5 exhibit an antiferromagnetic coupling between the anions, whereas a ferromagnetic coupling between anions and cations is the dominant interaction in 3. 6 behaves as a magnetically isolated compound, its susceptibility being the simple addition of the independent contributions of the uncoupled paramagnetic cations and anions.

  11. Substituent effects on the properties of the hemi-bonded complexes (XH2P···NH2Y)(+) (X, Y=H, F, Cl, Br, NH2, CH3, OH).

    PubMed

    Ji, Li Fei; Li, An Yong; Li, Zhuo Zhe; Ge, Zhi Xing

    2016-01-01

    Ab initio calculations have been performed to study the structures, binding energies, and bonding properties of the hemi-bonded binary complexes (XH2P···NH2Y)(+) with the substituents X and Y being H, F, Cl, Br, NH2, CH3, and OH. The P···N interactions in these open-shelled systems have typical pnicogen bond characteristics but much stronger than the usual pnicogen bonds in closed-shell systems. This P···N bond can be strengthened by an electron-withdrawing substituent X or an electron-donating substituent Y, the bonding energy varies from 17 kcal mol(-1) of (CH3H2P···NH2F)(+) to 54 kcal mol(-1) of (FH2P···NH2CH3)(+). A nearly linear X-P···N arrangement is required by the pnicogen bond P···N and results in a strong hyperconjugation and charge transfer from the N lone pair to the X-P σ* antibond orbital for α spin, the P···N interaction is described as a single-electron σ bond of β spin. The AIM and NBO analyses revealed that the P···N bonds in the majority of the hemi-bonded complexes are partly covalent in nature. Graphical Abstract The P···N interactions in the open-shelled systems (XH2P···NH2Y)(+) (X, Y=H, F, Cl, Br, NH2, CH3, OH) with bonding energy of 17~54 kcal mol(-1) have typical pnicogen bond characteristics but much stronger than the usual pnicogen bonds in closed-shell systems. This P···N bond can be strengthened by an electron-withdrawing substituent X or an electron-donating substituent Y.

  12. Probing the electronic structure and chemical bonding in tricoordinate uranyl complexes UO2X3- (X = F, Cl, Br, I): competition between Coulomb repulsion and U-X bonding.

    PubMed

    Su, Jing; Dau, Phuong Diem; Qiu, Yi-Heng; Liu, Hong-Tao; Xu, Chao-Fei; Huang, Dao-Ling; Wang, Lai-Sheng; Li, Jun

    2013-06-01

    While uranyl halide complexes [UO2(halogen)n](2-n) (n = 1, 2, 4) are ubiquitous, the tricoordinate species have been relatively unknown until very recently. Here photoelectron spectroscopy and relativistic quantum chemistry are used to investigate the bonding and stability of a series of gaseous tricoordinate uranyl complexes, UO2X3(-) (X = F, Cl, Br, I). Isolated UO2X3(-) ions are produced by electrospray ionization and observed to be highly stable with very large adiabatic electron detachment energies: 6.25, 6.64, 6.27, and 5.60 eV for X = F, Cl, Br, and I, respectively. Theoretical calculations reveal that the frontier molecular orbitals are mainly of uranyl U-O bonding character in UO2F3(-), but they are from the ligand valence np lone pairs in the heavier halogen complexes. Extensive bonding analyses are carried out for UO2X3(-) as well as for the doubly charged tetracoordinate complexes (UO2X4(2-)), showing that the U-X bonds are dominated by ionic interactions with weak covalency. The U-X bond strength decreases down the periodic table from F to I. Coulomb barriers and dissociation energies of UO2X4(2-) → UO2X3(-) + X(-) are calculated, revealing that all gaseous dianions are in fact metastable. The dielectric constant of the environment is shown to be the key in controlling the thermodynamic and kinetic stabilities of the tetracoordinate uranyl complexes via modulation of the ligand-ligand Coulomb repulsions.

  13. 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

    2014-01-01

    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.

  14. Conversion of xylan, d-xylose and lignocellulosic biomass into furfural using AlCl3 as catalyst in ionic liquid.

    PubMed

    Zhang, Luxin; Yu, Hongbing; Wang, Pan; Dong, Heng; Peng, Xinhong

    2013-02-01

    In order to define a new green catalytic pathway for the production of furfural, the catalyzed conversion of xylan into furfural in 1-butyl-3-methylimidazolium chloride was studied by using mineral acids and metal chlorides as catalysts under microwave irradiation. Amongst these catalysts, AlCl(3) resulted in the highest furfural yield of 84.8% at 170°C for 10s. The effect of AlCl(3) on the conversion efficiency of d-xylose and untreated lignocellulosic biomass was also investigated, the yields of furfural from corncob, grass and pine wood catalyzed by AlCl(3) in [BMIM]Cl were in the range of 16-33%. [BMIM]Cl and AlCl(3) could be recycled for four runs with stable catalytic activity. AlCl(3) is less corrosive than mineral acids, and the use of ionic liquid as reaction medium will no longer generate toxic wastewater, thus this reaction system is more ecologically viable. PMID:23306118

  15. 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.

  16. 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.

  17. Synthesis and the crystal and molecular structures of (H{sub 3}L . Cl)[CoCl{sub 4}] and H{sub 2}L[CuBr{sub 4}] (L is 2,4,6-Tri(N,N-dimethylamino)methylphenol)

    SciTech Connect

    Kovalchukova, O. V.; Stash, A. I.; Strashnova, S. B.; Romashkina, E. P.; Zaitsev, B. E.

    2010-05-15

    The complex compounds (H{sub 3}L . Cl)[CoCl{sub 4}] (I) and H{sub 2}L[CuBr{sub 4}] (II), where L is 2,4,6-tri(N,N-dimethylamino)methylphenol, were isolated in the crystalline state and studied by X-ray diffraction. The organic cations were found to be outer-sphere ligands. All three nitrogen atoms of the tertiary amino groups are protonated. In compound I, the H{sub 3}L{sup 3+} cation exists as the cis tautomer. In compound II, the H{sub 2}L{sup 2+} dication exists as the trans isomer. In the crystal structure, the dications are arranged in layers via hydrogen bonds.

  18. 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.

  19. Spectral, luminescence, and lasing properties of Nd/sup 3 +/ ions in systems utilizing GaCl/sub 3/--SOCl/sub 2/ and AlCl/sub 3/--SOCl/sub 2/ inorganic liquid media

    SciTech Connect

    Mochalov, I.V.; Bondareva, N.P.; Bondarev, A.S.; Markosov, S.A.

    1982-05-01

    An investigation is made of the absorption and luminescence spectra and of the decay kinetics of the /sup 4/F/sub 3/2/ metastable level of the Nd/sup 3 +/ ion in the GaCl/sub 3/--SOCl/sub 2/ concentration series and in an AlCl/sub 3/--SOCl/sub 2/:Nd/sup 3 +/ sample at temperatures of 300, 77, and 4.2 /sup 0/K. It is established that in GaCl/sub 3/--SOCl/sub 2/ and AlCl/sub 3/--SOCl/sub 2/ systems the neodymium ions form several types of activator centers corresponding to different structures of the nearest coordination sphere of the neodymium ion, which is a complexing agent. The phenomenological Judd--Ofelt model is used to calculate the most important characteristics of the radiative transitions of the Nd/sup 3 +/ ion in a GaCl/sub 3/--SOCl/sub 2/--NdCl/sub 3/ system. Lasing at 1.058 ..mu.. with a threshold of 0.5 J/cm was obtained in a GaCl/sub 3/--SOCl/sub 2/ system.

  20. 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).

  1. Synthesis of furfural from xylose, xylan, and biomass using AlCl3·6H2O in biphasic media via xylose isomerization to xylulose.

    PubMed

    Yang, Yu; Hu, Chang-Wei; Abu-Omar, Mahdi M

    2012-02-13

    Furfural was prepared in high yields (75 %) from the reaction of xylose in a water-tetrahydrofuran biphasic medium containing AlCl(3)·6H2O and NaCl under microwave heating at 140 °C. The reaction profile revealed the formation of xylulose as an intermediate en route to the dehydration product (furfural). The reaction under these conditions reached completion in 45 min. The aqueous phase containing AlCl(3)·6H(2)O and NaCl could be recycled multiple times (>5) without any loss of activity or selectivity for furfural. Extension of this biphasic reaction system to include xylan as the starting material afforded furfural in 64 % yield. The use of corn stover, pinewood, switchgrass, and poplar gave furfural in 55, 38, 56, and 64 % yield, respectively, at 160 °C. Even though AlCl(3)·6H(2)O did not affect the conversion of crystalline cellulose, moderate yields of the by-product 5-hydroxymethylfurfural (HMF) were noted. The highest HMF yield of 42 % was obtained from pinewood. The coproduction of HMF and furfural from biomass was attributed to the weakening of the cellulose network in the biomass, as a result of hemicellulose hydrolysis. The multifunctional capacity of AlCl(3)·6H(2)O (hemicellulose hydrolysis, xylose isomerization, and xylulose dehydration) in combination with its ease of recyclability make it an attractive candidate/catalyst for the selective synthesis of furfural from various biomass feedstocks.

  2. A general synthetic route to [Cu(X)(NHC)] (NHC = N-heterocyclic carbene, X = Cl, Br, I) complexes† †Electronic supplementary information (ESI) available: Optimisation details and full characterisation data. CCDC 940850–940853. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3cc45488f Click here for additional data file.

    PubMed Central

    Santoro, Orlando; Collado, Alba; Slawin, Alexandra M. Z.; Nolan, Steven P.

    2013-01-01

    A one-pot procedure for the synthesis of [Cu(X)(NHC)] (X = Cl, Br, I) is reported. The reaction is applicable to a wide range of saturated and unsaturated NHC ligands, is scalable and proceeds under mild conditions using technical grade solvents in air. PMID:24087835

  3. Structural parameters, vibrational spectra and centrifugal distortion constants of F(CN)C dbnd NX (X = H, F, Cl, Br) and CH 3(Y)C dbnd NH (Y = H, CN)

    NASA Astrophysics Data System (ADS)

    Durig, James R.; Zhou, Sarah Xiaohua; Zhou, Carmen Xiaomin; Durig, Nicole E.

    2010-04-01

    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 a variety of basis sets have been carried out for the F(CN)C dbnd NX (X = H, F, Cl, Br) and CH 3(Y)C dbnd NH (Y = H, CN) 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 F(CN)C dbnd NBr with the ab initio MP2/6-311+G(d) predicted parameters, adjusted r0 parameters have been obtained. The structural parameters are: distances (Å) (N-Br) = 1.865(3); (C dbnd N) = 1.270(3); (C-F) = 1.327(3); (C-C) = 1.437(3); (C tbnd N) = 1.160(3); and angles (°) ∠BrNC = 114.4(5); ∠NCF = 127.4(5); ∠NCC = 119.7(5). These reported parameters have much lower uncertainties than those previously reported from the microwave data. Similar theoretical calculations have been carried out for CH 3(Y)C dbnd NH (Y = H, CN) and r0 structural parameters have been obtained for both the cis and trans conformers of ethylidenimine, CH 3(H)C dbnd NH, and for cis iminopyruvonitrile, CH 3(CN)C dbnd NH utilizing previously reported microwave rotational constants. For CH 3(H)C dbnd NH the determined r0 heavy atom parameters for the cis [trans] form are: distances (Å) (C dbnd N) = 1.276(3) [1.275(3)]; (C-C) = 1.500(3) [1.508(3)]; angles (°) ∠(HN dbnd C) = 109.4(5) [108.8(5)]; ∠(N dbnd CC) = 121.2(5) [127.2(5)]; ∠(HCC) = 116.2(5) [116.4(5)]. Centrifugal distortion constants have been obtained for all of the molecules from the ab initio predicted force constants and the values are compared to the experimentally determined values when available. The results of these studies are compared to the corresponding quantities of some other similar molecules.

  4. Lewis acidities and hydride, fluoride, and X- affinities of the BH(3-n)Xn compounds for (X = F, Cl, Br, I, NH2, OH, and SH) from coupled cluster theory.

    PubMed

    Grant, Daniel J; Dixon, David A; Camaioni, Donald; Potter, Robert G; Christe, Karl O

    2009-09-21

    Atomization energies at 0 K and enthalpies of formation at 0 and 298 K are predicted for the BH(4-n)X(n)(-) and the BH(3-n)X(n)F(-) compounds for (X = F, Cl, Br, I, NH(2), OH, and SH) from coupled cluster theory (CCSD(T)) calculations with correlation-consistent basis sets and with an effective core potential on I. To achieve near chemical accuracy (+/-1.0 kcal/mol), additional corrections were added to the complete basis set binding energies. The hydride, fluoride, and X(-) affinities of the BH(3-n)X(n) compounds were predicted. Although the hydride and fluoride affinities differ somewhat in their magnitudes, they show very similar trends and are both suitable for judging the Lewis acidities of compounds. The only significant differences in their acidity strength orders are found for the boranes substituted with the strongly electron withdrawing and back-donating fluorine and hydroxyl ligands. The highest H(-) and F(-) affinities are found for BI(3) and the lowest ones for B(NH(2))(3). Within the boron trihalide series, the Lewis acidity increases monotonically with increasing atomic weight of the halogen, that is, BI(3) is a considerably stronger Lewis acid than BF(3). For the X(-) affinities in the BX(3), HBX(2), and H(2)BX series, the fluorides show the highest values, whereas the amino and mercapto compounds show the lowest ones. Hydride and fluoride affinities of the BH(3-n)X(n) compounds exhibit linear correlations with the proton affinity of X(-) for most X ligands. Reasons for the correlation are discussed. A detailed analysis of the individual contributions to the Lewis acidities of these substituted boranes shows that the dominant effect in the magnitude of the acidity is the strength of the BX(3)(-)-F bond. The main contributor to the relative differences in the Lewis acidities of BX(3) for X, a halogen, is the electron affinity of BX(3) with a secondary contribution from the distortion energy from planar to pyramidal BX(3). The B-F bond dissociation

  5. Effects of partial anion substitution on the thermoelectric properties of silver(I) chalcogenide halides in the system Ag{sub 5}Q{sub 2}X with Q=Te, Se and S and X=Br and Cl

    SciTech Connect

    Eckstein, Nadine; Nilges, Tom; Decourt, Rodolphe; Bobet, Jean-Louis; Chevalier, Bernard

    2011-04-15

    A selection of mixed conducting silver chalcogenide halides of the general formula Ag{sub 5}Q{sub 2}X with Q=sulfur, selenium and tellurium and X=chlorine and bromine has been investigated due to their thermoelectric properties. Recently, the ternary counterpart Ag{sub 5}Te{sub 2}Cl showed a defined d{sup 10}-d{sup 10} interaction in the disordered cation substructure at elevated temperatures where Ag{sub 5}Te{sub 2}Cl is present in its high temperature {alpha}-phase. A significant drop of the thermal diffusivity has been observed during the {beta}-{alpha} phase transition reducing the values from 0.12 close to 0.08 mm{sup 2} s{sup -1}. At the same transition the thermopower reacts on the increasing silver mobility and jumps towards less negative values. Thermal conductivities, thermopower and thermal diffusivity of selected compounds with various grades of anion substitution in Ag{sub 5}Q{sub 2}X were determined around the silver-order/disorder {beta}-{alpha} phase transition. A formation of attractive interactions could be observed for selenium substituted phases while no effect was detected for bromide and sulfide samples. Depending on the grade and type of substitution the thermopower changes significantly at and after the {beta}-{alpha} phase transition. Thermal conductivities are low reaching values around 0.2-0.3 W m{sup -1} K{sup -1} at 299 K. Partial anion exchange can substantially tune the thermoelectric properties in Ag{sub 5}Q{sub 2}X phases. -- Graphical abstract: A structure section of the {alpha}-Ag{sub 5}Te{sub 2}Cl structure type and the thermopower evolution of Ag{sub 5}Te{sub 2}Cl{sub 0.4}Br{sub 0.6} undergoing a silver ion order/disorder phase transition. Display Omitted Research highlights: > We report on thermoelectric properties of silver(I) chalcogenide halides. > We examine thermopower, thermal diffusivity and thermal behavior. > Silver mobility, phase transitions and order/disorder phenomena are discussed. > Partial anion exchange can

  6. 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.

  7. Doped-CuCl2/Al2O3 catalysts for ethylene oxychlorination: Influence of additives on the nature of active phase and reducibility

    NASA Astrophysics Data System (ADS)

    Gianolio, D.; Muddada, N. B.; Olsbye, U.; Lamberti, C.

    2012-08-01

    Doped CuCl2/Al2O3 is an industrial catalyst used to produce dichloroethane, key intermediate of the polyvinyl chloride (PVC) chemistry. Using in situ and operando X-ray absorption spectroscopies, combined with laboratory techniques, we succeeded in understanding the nature of the active phase and the role played by most used additives for fluid and fixed beds technologies (LiCl, KCl, CsCl, MgCl2, and LaCl3). Moreover we were able to quantify relative fraction, reducibility and dispersion of Cu-phases adjoining catalytic tests in a pulse reactor. EXAFS and XANES highlighted that all additives contribute more or less efficiently in increasing the fraction of the active species (supported CuCl2). EXAFS directly, UV-vis and IR spectroscopies indirectly proved the formation of mixed salts, when KCl or CsCl are added, so displacing the rate determining step from the CuCl oxidation to the CuCl2 reduction. Fully oxidized catalyst is inactive, so copper in the working catalyst, exhibits a I/II mixed valence state. Coupling the ethylene conversion, measured with a pulse reactor, with XANES spectra collected after interaction with C2H4, we could differentiate the ability of doped samples to be reduced by ethylene. We obtained slightly different results explainable by the different dispersion of the active phase, measured by CO chemisorption.

  8. 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

  9. 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.

  10. 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).

  11. 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.

  12. Core-shell Cd0.2Zn0.8S@BiOX (X = Cl, Br and I) microspheres: a family of hetero-structured catalysts with adjustable bandgaps, enhanced stability and photocatalytic performance under visible light irradiation.

    PubMed

    Zhou, Yannan; Wen, Ting; Chang, Binbin; Yang, Baocheng; Wang, Yonggang

    2016-09-21

    Heterostructures consisting of two semiconductors have merited considerable attention in photocatalytic applications due to synergistic effects in complex redox processes. The incorporation of solid solutions into such architectures can further offer extra variability to control the bandgap. In this study, we report the fabrication of a series of core-shell Cd0.2Zn0.8S@BiOX (X = Cl, Br and I) microspheres via a solvothermal route that lead to enhanced photocatalytic performance under visible light irradiation. By optimizing the synthesis conditions, uniform and porous Cd0.2Zn0.8S@BiOX microspheres were achieved. The products were thoroughly characterized by X-ray diffraction studies, scanning electron microscopy, transmission electron microscopy, photoluminescence studies, absorption measurements and the photodegradation of RhB. Remarkably, the electronic structures of Cd0.2Zn0.8S@BiOX composites can be continuously tuned by varying the composition of BiOX to achieve the best catalytic performance under visible light irradiation. Finally, this greatly enhanced visible-light-driven photocatalytic efficiency was observed in the optimized Cd0.2Zn0.8S@BiOI composites when compared to their single-component counterparts, which may be attributed to increased light absorption and improved electron-hole separation. The photocatalytic mechanism has also been proposed based on the experimental evidences and the theoretical band positions of Cd0.2Zn0.8S@BiOI. PMID:27510184

  13. 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

    NASA Astrophysics Data System (ADS)

    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).

  14. 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.

  15. 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. PMID:17388388

  16. 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.

  17. 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.

  18. Spin-Orbit Effect on the Molecular Properties of TeXn (X = F, Cl, Br, and I; n = 1, 2, and 4): A Density Functional Theory and Ab Initio Study.

    PubMed

    Moon, Jiwon; Kim, Joonghan

    2016-09-29

    Density functional theory (DFT) and ab initio calculations, including spin-orbit coupling (SOC), were performed to investigate the spin-orbit (SO) effect on the molecular properties of tellurium halides, TeXn (X = F, Cl, Br, and I; n = 1, 2, and 4). SOC elongates the Te-X bond and slightly reduces the vibrational frequencies. Consideration of SOC leads to better agreement with experimental values. Møller-Plesset second-order perturbation theory (MP2) seriously underestimates the Te-X bond lengths. In contrast, B3LYP significantly overestimates them. SO-PBE0 and multireference configuration interactions with the Davidson correction (MRCI+Q), which include SOC via a state-interaction approach, give the Te-I bond length of TeI2 that matches the experimental value. On the basis of the calculated thermochemical energy and optimized molecular structure, TeI4 is unlikely to be stable. The use of PBE0 including SOC is strongly recommended for predicting the molecular properties of Te-containing compounds.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Dry etching of NiFe/Co and NiFe/Al-O/Co multilayers in an inductively coupled plasma of Cl{sub 2}/Ar mixture

    SciTech Connect

    Ra, H.-W.; Hahn, Y.B.; Song, K.S.; Park, M.H.; Hong, Y.K.

    2004-11-01

    Dry etching of NiFe/Co and NiFe/Al-O/Co multilayers was carried out in inductively coupled Cl{sub 2}/Ar plasmas. An ion-enhanced etch mechanism took a critical role for desorption of chlorine etch products. NiFe/Al-O/Co showed a faster etch rate than NiFe/Co at various etch conditions. Anisotropic and smooth features were obtained using a photoresist mask. Sidewall contamination with etch products was observed at a higher Cl{sub 2} concentration (>50%). Postetch cleaning of the etched samples in deionized water reduced the chlorine residues substantially.

  4. The structure and chemical bonding in the N(2)-CuX and N(2)...XCu (X = F, Cl, Br) systems studied by means of the molecular orbital and Quantum Chemical Topology methods.

    PubMed

    Kisowska, Karolina; Berski, Slawomir; Latajka, Zdzislaw

    2008-12-01

    Ab initio studies carried out at the MP2(full)/6-311+G(2df) and MP2(full)/aug-cc-pVTZ-PP computational levels reveals that dinitrogen (N(2)) and cuprous halides (CuX, X = F, Cl, Br) form three types of systems with the side-on and end-on coordination of N(2): N[triple bond]N-CuX (C(infinity v)), N(2)-CuX (C(2v)) stabilized by the donor-acceptor bonds and weak van der Waals complexes N(2)...XCu (C(2v)) with dominant dispersive forces. An electron density transfer between the N(2) and CuX depends on type of the N(2) coordination and a comparison of the NPA charges yields the [N[triple bond]N](delta+)-[CuX](delta-) and [N(2)](delta-)-[CuX](delta+) formula. According to the NBO analysis, the Cu-N coordinate bonds are governed by predominant LP(N2)-->sigma*(Cu-X) "2e-delocalization" in the most stable N[triple bond]N-CuX systems, meanwhile back donation LP(Cu)-->pi*(N-N) prevails in less stable N(2)-CuX molecules. A topological analysis of the electron density (AIM) presents single BCP between the Cu and N nuclei in the N[triple bond]N-CuX, two BCPs corresponding to two donor-acceptor Cu-N bonds in the N(2)-CuX and single BCP between electron density maximum of the N[triple bond]N bond and halogen nucleus in the van der Waals complexes N(2)...XCu. In all systems values of the Laplacian nabla(2)rho(r)(r(BCP)) are positive and they decrease following a trend of the complex stability i.e. N[triple bond]N-CuX (C(infinity v)) > N(2)-CuX (C(2v)) > N(2)...XCu (C(2v)). A topological analysis of the electron localization function (ELF) reveals strongly ionic bond in isolated CuF and a contribution of covalent character in the Cu-Cl and Cu-Br bonds. The donor-acceptor bonds Cu-N are characterized by bonding disynaptic basins V(Cu,N) with attractors localized at positions corresponding to slightly distorted lone pairs V(N) in isolated N(2). In the N[triple bond]N-CuX systems, there were no creation of any new bonding attractors in regions where classically the donor-acceptor bonds

  5. 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.

  6. 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.

    PubMed

    Dobbins, Tabbetha; Abrecht, Mike; Uprety, Youaraj; Moore, Kristan

    2009-05-20

    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% TiCl3catalyzed 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.

  7. 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.

  8. Changes in Phase Composition of NaAlH{sub 4}+FeCl{sub 2} Complex Hydride Exposed to Air

    SciTech Connect

    Roupcova, P.; Schneeweiss, O.

    2010-07-13

    Phase composition in AlNaH{sub 4} doped with FeCl{sub 2} was studied by Moessbauer spectroscopy and X-ray diffraction and stabilities in Ar and air were compared. The results show that the hydride disappeared during the exposition to air. The major sodium alanate hydride traps gaseous impurities and transforms to Na{sub 2}CO{sub 3} and Al(OH){sub 3}.

  9. Effect of manufacturing methods of AgCl/Al2O3 catalyst on selective catalytic reduction of NO(x).

    PubMed

    Kishida, Satoshi; Ju, Dong-Ying; Aritani, Hirofumi

    2011-01-01

    The AgCl/Al2O3 catalyst has potential for use in the selective catalytic reduction (SCR) of NO(x). A compound hydrocarbon, following oxygenation is used as a type of reducing agent. In this experiment, the AgCl/Al2O3 catalyst was produced by four different methods, and the differences among their reduction catalysis of NO(x) were compared. Ethanol was used as a type of reducing agent. X-ray diffraction analysis was performed to study the crystalline structure and scanning electron microscope and transmission electron microscope (TEM) were applied to determine the microindentation. The results indicated that, in the range of 350-400 degrees C, there was no significant difference on the NO(x) reduction rate; however, there was dispersion at high and low temperature ranges. The size of the AgCl particles was about 20-100 nm.

  10. 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. PMID:26726496

  11. 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. PMID:25404114

  12. 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.

  13. 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.

  14. 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.

  15. Optical properties of low-dimensional organic conductors with differently oriented conducting layers: (EDT-TTF)3Hg2Br6 and (EDT-TTF)3Hg(SCN)3I0.5(PhCl)0.5

    NASA Astrophysics Data System (ADS)

    Vlasova, R. M.; Petrov, B. V.; Semkin, V. N.; Zhilyaeva, E. I.; Torunova, S. A.

    2013-01-01

    Spectral optical investigations of two low-dimensional organic molecular conductors with differently oriented conducting layers of ethylenedithiotetrathiafulvalene (EDT-TTF) molecules, namely, the (EDT-TTF)3Hg2Br6 and (EDT-TTF)3Hg(SCN)3I0.5(PhCl)0.5 single crystals, have been carried out. The polarized reflectance spectra of the single crystals have been measured in the frequency range 700-6500 cm-1 (0.087-0.810 eV) at temperatures from 300 to 15 K. The optical conductivity spectra have been obtained using the Kramers-Kronig relations, and their quantitative analysis has been performed in terms of a theoretical model that takes into account electron-electron correlations in the approximation of the Hubbard Hamiltonian for trimerized stacks, the vibronic coupling, and the influence of the counterion on the electronic states in the trimer. A satisfactory agreement between the theoretical and experimental spectra for both crystals made it possible to estimate the parameters of the electronic structure of the crystals in the conducting plane: the integral t of the electron transfer between the EDT-TTF molecules in the trimer, the energy U of the Coulomb repulsion between two electrons (holes) in one EDT-TTF molecule, the electron transfer damping constant γ e , the energy shift Δ of the molecular orbital under the influence of the anions and vibronic coupling, the vibronic coupling constant g n , and the binding energy E p of the molecular polaron. It has been found that there are large differences in the anisotropies of the optical properties and the obtained Hubbard parameters of the electronic structure for the studied crystals.

  16. Theoretical analysis of NMR shieldings of group-11 metal halides on MX (M = Cu, Ag, Au; X = H, F, Cl, Br, I) molecular systems, and the appearance of quasi instabilities on AuF.

    PubMed

    Maldonado, Alejandro F; Melo, Juan I; Aucar, Gustavo A

    2015-10-14

    Accurate calculations of nuclear magnetic shieldings of group-11 metal halides, σ(M; MX) (M = Cu, Ag, Au; X = H, F, Cl, Br, I), were performed with relativistic and nonrelativistic theoretical schemes in order to learn more about the importance of the involved electronic mechanisms that underlie such shieldings. We applied state of the art schemes: polarization propagators at a random phase level of approach (PP-RPA); spin-free Hamiltonian (SF); linear response elimination of small component (LRESC) and density functional theory (DFT) with two different functionals: B3LYP and PBE0. The results from DFT calculations are not close to those from the relativistic polarization propagator calculations at the RPA level of approach (RelPP-RPA), in line with previous results. The spin-orbit (SO) contribution to a shielding constant is important only for MF molecules (M = Cu, Ag, Au). Different electronic mechanisms are considered within the LRESC method, bunched into two groups: core- and ligand-dependent. For the analysed shieldings the core-dependent electronic mechanisms are the most important ones; the ligand-dependent being only important for MF molecules. An out of range value for σ(Au) is found in AuF. It was previously reported in the literature, either originated in the large fluorine electronegativity together with large spin-orbit coupling contributions; or, due to Fermi-contact contributions. We argue here that such an unexpected large value is an artifact originated in the appearance of quasi instabilities, and show how to handle this apparent problem.

  17. 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.

  18. 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.

  19. Low to negligible BrO/SO2 ratios at two subduction-zone volcanoes

    NASA Astrophysics Data System (ADS)

    Bobrowski, Nicole; Hörmann, Christoph; Mori, Toshiya; Platt, Ulrich

    2014-05-01

    In July 2013 a measurement campaign took place on Kyushu, Japan, investigating the BrO/SO2 ratio in the plume of Sakurajima and Aso. Multi-Axis-Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements were carried out at four sides on Sakurajima Island, with a maximum distance of about 5 km downwind, and assuming a wind speed of 5 m/s (corresponding to a plume age of about 15 minutes). At Aso measurements took place on the western slope of the active crater and at the crater rim. The MAX-DOAS data of both sites were evaluated for BrO and SO2 slant column densities (SCDs). In the following, BrO/SO2 ratios were calculated to overcome dilution effects and to investigate the BrO formation processes in the ash-laden plume of Sakurajima and the volcanic plume of Aso which is characterized by emissions from a fumarolic area and a mud pool. The BrO/SO2 ratios of the measurement have been below the detection limit for Aso as well as during most of the measurement days at Sakurajima with the only exception on 15th July 2013, when a BrO/SO2 ratio of ~ 1 x 10-5 could be determined. After very high BrO/SO2 ratios at Sakurajima that were reported by C. Lee et al. (2005) our results seem to be unexpected but nevertheless match the general geological settings at both volcanoes. In a recent paper, Shinohara (2013) summarized and compared chlorine emissions from the Japanese volcanic arc with global chlorine emissions from arc volcanoes and pointed out that the volcanic gas emissions in Japan are quite Cl-poor compared to those at other subduction zones. In the recent past it has been found that low chlorine emissions can occur together with nevertheless high bromine emissions (Nyiragongo, Bobrowski et al., 2013). However, looking up Br/Cl ratios (of condensate measurements at fumaroles) of the Japanese arc volcanism summarized in Gerlach, 2004 a comparatively low Br/Cl ratio is added with 6-7 x 10-4 (global arc mean 2 x 10-3) to the already poor chlorine emissions. We

  20. An experimental and theoretical study of the aluminium species present in mixtures of AlCl3 with the ionic liquids [BMP]Tf2N and [EMIm]Tf2N.

    PubMed

    Eiden, Philipp; Liu, Qunxian; Zein El Abedin, Sherif; Endres, Frank; Krossing, Ingo

    2009-01-01

    It is known that nano- or microcrystalline aluminium may be electrodeposited from mixtures of AlCl(3) and the ionic liquids 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([BMP]Tf(2)N) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf(2)N), and that two phases form with higher formal concentrations of AlCl(3) (at 1.6 mol L(-1) (x(Al)=0.33) and 2.5 mol L(-1) (x(Al)=0.39), respectively). This account analyzes the hitherto unknown molecular nature of these mixtures by a detailed experimental (multinuclear NMR and Raman spectroscopies) and theoretical study (BP86/TZVP DFT calculations, including COSMO solvation energies). The addition of AlCl(3) to the two liquids first leads to complexation with [Tf(2)N](-) and then disproportionation of the initial [AlCl(x)(Tf(2)N)(y)](-) complexes give Al(Tf(2)N)(3) and [AlCl(4)](-). At high concentrations of AlCl(3), the lower phase consists almost completely of Al(Tf(2)N)(3), whereas in the upper phase [AlCl(4)](-) is the dominant species. Electrodeposition of aluminium in the upper phase occurs from mixed AlCl(x)(Tf(2)N)(y) species, most likely from [AlCl(2)(Tf(2)N)(2)](-) formed in small concentrations at the phase boundary between the [AlCl(4)](-) and the Al(Tf(2)N)(3) layers. All the findings are supported by DFT calculations as well as an X-ray crystal structure determination of Al(Tf(2)N)(3). The latter was separated from the mixture by sublimation on a preparative scale. It was independently prepared from AlEt(3) and HNTf(2) and fully characterized. Moreover, the ionic liquids [BMP]AlCl(4) (m.p. 74 degrees C) and [EMIm]AlCl(4) (m.p. -7 degrees C), which mainly form the upper layer in the biphasic regime, were independently prepared and also fully characterized. PMID:19229940

  1. Comment on ``Annual variation of geomagnetic activity'' by Alicia L. Clúa de Gonzales et al.

    NASA Astrophysics Data System (ADS)

    Sonnemann, G. R.

    2002-10-01

    Clúa de Gonzales et al. (J. Atmos. Terr. Phys. 63 (2001) 367) analyzed the monthly means of the geomagnetic /aa-index available since 1868 and found enhanced geomagnetic activity in July outside of the known seasonal course of semiannual variation. They pointed out that this behavior is mainly caused by the high values of the geomagnetic activity. Their analysis confirmed results obtained from an analysis of Ap-values nearly 30 years ago but widely unknown to the scientific community. At that time the entire year was analyzed using running means of the activity values averaged to the same date. Aside from the July period, the calculations revealed distinct deviations from the seasonal course-called geomagnetic singularities. The most marked singularity occurs from the middle of March to the end of March characterized by a strong increase from, on average, relatively calm values to the actually strongest ones during the entire year. Some typical time patterns around and after equinox are repeated half a year later. An analysis in 1998 on the basis of the available /aa-values confirmed the findings derived from Ap-values and the local activity index Ak from Niemegk, Germany available since 1890. The new results will be presented and discussed. Special attention is paid to the statistical problem of the persistence of geomagnetic perturbations. The main problem under consideration is that the variation of the mean activity is not caused by an accidental accumulation of strong perturbations occurring within certain intervals of days. We assume that the most marked variations of the mean value are not accidental and result from internal processes within the earth's atmosphere but different, particularly small-scale features, are most probably accidental.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. New halide-centered discrete Ag(I)(8) cubic clusters containing diselenophosphate ligands, [Ag(8)(X)[Se(2)P(OR)(2)](6)](PF(6)) (X = Cl, Br; R = Et, Pr, (i)Pr): syntheses, structures, and DFT calculations.

    PubMed

    Liu, C W; Haia, Hsien-Chung; Hung, Chiu-Mine; Santra, Bidyut Kumar; Liaw, Ben-Jie; Lin, Zhenyang; Wang, Ju-Chun

    2004-07-12

    Six clusters Ag(8)(micro(8)-X)[Se(2)P(OR)(2)](6)(PF(6)) (R = Et, X = Cl, 1a, X = Br, 1b; R = Pr, X = Cl, 2a, X = Br, 2b; R = (i)Pr, X = Cl, 3a, X = Br, 3b) were isolated from the reaction of [Ag(CH(3)CN)(4)](PF(6)), NH(4)[Se(2)P(OR)(2)], and Bu(4)NX in a molar ratio of 4:3:1 in CH(2)X(2). Positive FAB mass spectra show m/z peaks at 2573.2 for 1a, 2617.3 for 1b, 2740.9 for 2a, 2786.9 for 2b, 2742.3 for 3a, and 2787.0 for 3b due to respective molecular cation, (M - PF(6))(+). (31)P NMR spectra of 1a-3b display a singlet at delta 82.3, 81.5, 82.9, 81.7, 76.3, and 75.8 ppm with a set of satellites (J(PSe) = 661, 664, 652, 652, 656, and 656 Hz, respectively). The X-ray structure (1a-2b) consists of a discrete cationic cluster in which eight silver ions are linked by six diselenophosphate ligands and a central micro(8)-Cl or micro(8)-Br ion with a noncoordinating PF(6)(-) anion. The shape of the molecule is a halide-centered distorted Ag(8) cubic cluster. The dsep ligand exhibits a tetrametallic tetraconnective (micro(2), micro(2)) coordination pattern, and each caps on a square face of the cube. Each silver atom of the cube is coordinated by three selenium atoms and the central chloride or bromide ion. Additionally, molecular orbital calculations at the B3LYP level of the density functional theory have been carried out to study the Ag-micro(8)-X (X = Cl, Br) interactions for cluster cations [Ag(8)(micro(8)-X)[Se(2)P(OR)(2)](6)](+). Calculations show very weak bonding interactions exist between micro(8)-X and Ag atoms of the cube. PMID:15236560

  7. Synthesis and luminescent properties of Sr3Al2O5Cl2: Eu2+, Dy3+ rod-like nanocrystals

    NASA Astrophysics Data System (ADS)

    Wang, Zhengliang; Zhang, Qiuhan; Rong, Meizhu; Tan, Huiying; Wang, Qin; Zhou, Qiang; Chen, Guo

    2016-08-01

    White long afterglow phosphor with nano-rods, Sr3Al2O5Cl2: Eu2+, Dy3+, has been successfully synthesized by the solid state reaction. Their structure, morphology, scanning electron microscopy, luminescent properties and long afterglow properties were investigated by X-ray diffraction, transmission electron microscopy luminescence spectra and the luminescence decay curve. The obtained phosphor Sr3Al2O5Cl2: Eu2+, Dy3+ exhibits two broad emission bands, which are located at ∼445 nm and ∼590 nm, respectively. White light can be observed from this phosphor with appropriate CIE values (x = 0.357, y = 0.332). The white afterglow duration of this phosphor is about 0.5 h (>0.35 mcd/m2).

  8. Synthetic and 1H and 13C NMRSpectral Studies on N-(Mono-substitutedphenyl)- acetamides and Substituted Acetamides, 2/3/4-YC6H4NH-COCH3-iXi (Y = CH3, F, Cl, Br, NO2; X = Cl, CH3; i = 0, 1, 2, 3)

    NASA Astrophysics Data System (ADS)

    Gowda, Basavalinganadoddy Thimme; Lakshmipathy, Shilpa; Lakshmipathy, Jayalakshmi K.

    2006-11-01

    Nineteen N-(2/3/4-methyl/halo/nitro-phenyl)-acetamides and substituted acetamides, 2/3/4- YC6H4NH-CO-CH3-iXi (Y = CH3, F, Cl, Br or NO2; X = Cl or CH3 and i = 0, 1, 2 or 3), have been prepared, characterized, and their 1H and 13C NMR spectra in solution measured and correlated. 1H and 13C NMR chemical shifts were assigned to the protons and carbon atoms, respectively, in line with those for similar compounds. Since the chemical shifts are dependent on the electron density around the nucleus or associated with the atom to which it is bound, the incremental shifts of the aromatic protons or carbon atoms due to -NH-CO-CH3-iXi and -CO-CH3-iXi (X = Cl or CH3 and i = 0, 1, 2, 3) in all the N-phenyl-substituted acetamides, C6H5NH-CO-CH3-iXi, are calculated by comparing the proton or carbon chemical shifts of these compounds with those of benzene or aniline. The incremental shifts due to the groups in the parent compounds have also been computed by comparing the chemical shifts of the protons or carbon atoms in these compounds with those of benzene or aniline, respectively. The computed incremental shifts and other data were used to calculate the 1H and 13C NMR chemical shifts of the substituted compounds in three different ways. The calculated chemical shifts by the three methods compared well with each other and with the observed chemical shifts, testing the validity of the principle of additivity of the substituent effects in these compounds. The variation of 1H NMR chemical shifts of either the aromatic or N-H protons, with the substituents in N-(phenyl)- and N-(2/3/4-chloro/methylphenyl)-acetamides and substituted acetamides did not follow the same trend, while the variation of the 13C NMR chemical shifts of C-1 and C=O carbon atoms and those of alkyl carbon atoms of these compounds followed more or less the same trend.

  9. Macrocyclic cyclooctene-supported AlCl-salen catalysts for conjugated addition reactions: effect of linker and support structure on catalysis.

    PubMed

    Madhavan, Nandita; Takatani, Tait; Sherrill, C David; Weck, Marcus

    2009-01-01

    AlCl-salen (salen=N,N'-bis(salicylidene)ethylenediamine dianion) catalysts supported onto macrocyclic oligomeric cyclooctene through linkers of varying length and flexibility have been developed to demonstrate the importance of support architecture on catalyst activity. The role played by the support and the linkers in dictating catalyst activity was found to vary for reactions with contrasting mechanisms, such as the bimetallic cyanide and the monometallic indole addition reactions. While the flexible support significantly enhanced the cyanide addition reaction, most likely by improving salen-salen interactions in the transition state, it lowered the reaction rate for the monometallic indole reaction. For both reactions, significant increase in catalytic activity was observed for catalysts with the longest linkers. The effect of the flexible macrocyclic support on catalysis was further exemplified by the enhanced activity of the supported catalyst in comparison with its unsupported analogue for the conjugate addition of tetrazoles, which is known to be catalyzed by dimeric mu-oxo-salen catalysts. Our studies with the cyclooctene supported AlCl-salen catalysts provides significant insights for rationally designing highly efficient AlCl-salen catalysts for a diverse set of reactions.

  10. 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

  11. Cd4As2Br3

    PubMed Central

    Kars, Mohammed; Roisnel, Thierry; Dorcet, Vincent; Rebbah, Allaoua; Otero-Diáz, L. Carlos

    2014-01-01

    Single crystals of Cd4As2Br3 (tetra­cadmium biarsenide tri­bromide) were grown by a chemical transport reaction. The structure is isotypic with the members of the cadmium and mercury pnictidohalides family with general formula M 4 A 2 X 3 (M = Cd, Hg; A = P, As, Sb; X = Cl, Br, I) and contains two independent As atoms on special positions with site symmetry -3 and two independent Cd atoms, of which one is on a special position with site symmetry -3. The Cd4As2Br3 structure consists of AsCd4 tetra­hedra sharing vertices with isolated As2Cd6 octa­hedra that contain As–As dumbbells in the centre of the octahedron. The Br atoms are located in the voids of this three-dimensional arrangement and bridge the different polyhedra through Cd⋯Br contacts. PMID:24764933

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Dendrite-Free Aluminum Electrodeposition from AlCl3-1-Ethyl-3-Methyl-Imidazolium Chloride Ionic Liquid Electrolytes

    NASA Astrophysics Data System (ADS)

    Pradhan, Debabrata; Reddy, Ramana G.

    2012-06-01

    A novel, dendrite-free electrorefining of aluminum scrap alloys (A360) was investigated by using a low-temperature AlCl3-1-ethyl-3-methyl-imidazolium chloride (EMIC) ionic liquid electrolyte on copper/aluminum cathodes. The bulk electrodeposition of aluminum was carried out at a fixed voltage of 1.5 V, temperatures 323 K to 383 K (50 °C to 110 °C), stirring rate (0 to 120 rpm), concentration (molar ratio AlCl3:EMIC = 1.25 to 2.0), and electrode surface modification (modified/unmodified). The study investigated the effect of electrode surface modification, cathode materials, temperature, stirring rate, electrolyte concentration, and deposition time on the deposit morphology of aluminum, cathode current density, and their role in production of dendrite-free aluminum deposit, which is essential for decreasing the production cost. The deposits were characterized using scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). It was shown that electrode surface modification, cathode overpotential, and stirring rate play an important role in dendrite-free deposit. Modified electrodes and stirring (60 rpm) eliminate dendritic deposition by reducing cathode overpotential below critical overpotential ( η_{{crt}} ≈ - 0.53V ) for dendrite formation. Pure aluminum (>99 pct) was deposited for all experiments with a current efficiency of 84 to 99 pct and energy consumption of 4.51 to 5.32 kWh/kg Al.

  18. 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.

  19. An N-TIMS Br Isotopic Study of Australian Playa Lakes

    NASA Astrophysics Data System (ADS)

    Schaefer, B. F.

    2013-12-01

    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 for 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 <0.05‰ (1SD) over an 24 month period with internal precision typically <0.03‰ (1SD) on single analyses. Australian playa lakes record variations of >5‰, comparable to that of the whole solar system. Regionality is implied on this preliminary data set whereby Lake Gairdner, which is sourced from a single, arid region lithology, is displaced from other, multi lithological sourced lakes from the same climatic zone. [1] Shouaker-Stash et al., Anal. Chem, 77; p4027-4033, 2005.

  20. Synthesis and X-ray structural characterization of a series of dimeric [Hg2(SePh)2X2(PR2R‧)2] compounds (R = tert-butyl; R‧ = 4-N,N-dimethylaniline and X = Cl, Br, I, SCN, SePh)

    NASA Astrophysics Data System (ADS)

    Stieler, Rafael; Faoro, Eliandro; Cechin, Camila Nunes; Floriano, Luana; Lang, Ernesto Schulz

    2015-01-01

    This article presents the syntheses and characterization of five new compounds with the general formula [Hg2(SePh)2X2(PR2R‧)2] (R = tert-butyl; R‧ = 4-N,N-dimethylaniline), where X = Cl (1a), Br (1b), I (1c), SCN (2), SePh (3). The compounds crystallized as dimeric {HgSe} units, although most of these chalcogenolate compounds appeared to be polymeric adamantanoid or fused adamantanoid species. The ligand structures of these compounds limited the growth of the molecular structures and promoted the formation of the dimeric form alone. The mercury centers were connected to one another through one μ-Cl and one μ-SePh bridge in 1a, and through two μ-SePh bridges in 1b, 1c, 2, and 3. The compounds were characterized by single crystal X-ray diffractometry, TGA, elemental analysis, and infrared spectroscopy.

  1. Temperature dependence on dry etching of Al{sub 2}O{sub 3} thin films in BCl{sub 3}/Cl{sub 2}/Ar plasma

    SciTech Connect

    Yang Xue; Kim, Dong-Pyo; Um, Doo-Seung; Kim, Gwan-Ha; Kim, Chang-Il

    2009-07-15

    During the etching process, the wafer surface temperature is an important parameter which influences the reaction probabilities of incident species, the vapor pressure of etch products, and the redeposition of reaction products on feature surfaces. In this study, the authors investigated that the effect of substrate temperature on the etch rate of Al{sub 2}O{sub 3} thin film and selectivity of Al{sub 2}O{sub 3} thin film over hard mask material (such as SiO{sub 2}) thin film in inductively coupled plasma as functions of Cl{sub 2} addition in BCl{sub 3}/Ar plasma, rf power, and dc-bias voltage based on the substrate temperature in range of 10-80 degree sign C. The elements existed on the surface were analyzed by energy dispersive x-ray and x-ray photoelectron spectroscopy.

  2. 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.

  3. Electrochemical Corrosion Behavior of Magnetron-Sputtered Al-Mo Gradient-Coated Steel in 3.5 wt.% NaCl Solution

    NASA Astrophysics Data System (ADS)

    Venugopal, A.; Narayanan, P. Ramesh; Sharma, S. C.; George, Koshy M.

    2016-03-01

    A gradient three-layer Al-Mo coating was deposited on steel using magnetron sputtering method. The corrosion properties of the coating were studied in 3.5 wt.% NaCl solution using electrochemical techniques, whereas the hydrogen-induced cracking (HIC) resistance was examined by constant-load tests using notched tensile specimens. These results were compared with conventional electroplated cadmium-coated steel. The results show that the gradient Al-Mo coating exhibits better corrosion and HIC resistance when compared to electroplated cadmium. This was due to the excellent corrosion resistance of the bottom aluminum-rich layer, while the top Mo-rich layer provided good lubrication properties.

  4. The preparation of nanosized polyethylene particles via novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/CNTs/AlEt3

    NASA Astrophysics Data System (ADS)

    Wang, J.; Guo, J. P.; Yi, J. J.; Huang, Q. G.; Li, H. M.; Li, Y. F.; Gao, K. J.; Yang, W. T.

    2014-08-01

    This paper reports the preparation of coral-shaped topological morphology nascent polyethylene (PE) particles promoted by the novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/carbon nanotubes (CNTs), with AlEt3 used as a cocatalyst. Scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM) and inductively coupled plasma (ICP) emission spectroscopy were used to determine the morphology of the catalyst particles and the content of (m-CH3PhO)TiCl3. The carbon nanotube surface was treated with Grignard Reagent prior to reacting with (m-CH3PhO)TiCl3. The catalyst system could effectively catalyze ethylene polymerization and ethylene with 1- hexene copolymerization, the catalytic activity could reach up to 5.8 kg/((gTi)h). Morphology of the obtained polymer particles by SEM and HR-TEM technique revealed that the nascent polyethylene particles looked like coral shape in micro-size. The multiwalled carbon nanotubes (MWCNTs) supported catalysts polymerized ethylene to form polymer nanocomposite in situ. The microscopic examination of this nanocomposite revealed that carbon nanoparticles in PE matrix had a good distribution and the cryogenically fractured surface was ductile-like when polymerization time was 2 min.

  5. 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

    2016-09-01

    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.

  6. 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.

  7. Solubility and Stability of Grossular in the System CaSiO3-Al2O3-NaCl-H2O at 800 C and 10 Kbar

    NASA Astrophysics Data System (ADS)

    Newton, R. C.; Manning, C. E.

    2006-12-01

    The solubility of grossular garnet (Ca3Al2Si3O12) in H2O-NaCl solutions was investigated in a piston-cylinder apparatus at 800°C, 10 kbar, at NaCl mole fractions (XNaCl) of 0-0.4 (68.4 wt% NaCl). Starting materials included synthetic corundum and grossular, and natural, very pure wollastonite. Solubilities were determined by weight changes of single crystals and polycrystalline aggregates enclosed in perforated Pt inner capsules which were in turn sealed with H2O and halite in larger Pt outer capsules. Grossular dissolves congruently at all NaCl mole fractions. Experimental XNaCl and measured solubilities (mol/kg H2O) are: 0, 0.0055(4); 0.05, 0.030(1); 0.1, 0.056(4); 0.2, 0.079(5); 0.3, 0.100(4); 0.4, 0.127(7). The large initial solubility enhancement with NaCl indicates complexing, probably to Na-aluminates which are also probably hydrates. All quenched fluids from NaCl-bearing runs with CaSiO3 were strongly basic (pH 11-12), indicating that Ca forms chloride. NaCl also produces great enhancement of wollastonite solubility (Newton and Manning, 2006). Solubility of corundum in CaSiO3-bearing brines and of wollastonite in Al2O3-bearing brines were measured up to grossular saturation. CaSiO3 together with NaCl increases corundum solubility up to 100-fold over pure H2O at 800°C and 10 kbar, but Al2O3 added to NaCl has only a small effect on wollastonite solubility, indicating that increased pH, rather than Ca-Al-(Si) complexing, accounts for the Al2O3 enhancement. Zoisite replaces corundum in equilibrium with grossular at XNaCl ≥ 0.3; this is the only departure from the quaternary system. The high solubility of grossular and high mobility of Al2O3 in basic chloride solutions at high P and T suggest that brine infiltration may be an important factor in metasomatism of deep-crust calcareous rocks.

  8. 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

  9. The formation of surface multilayers at the air-water interface from sodium diethylene glycol monoalkyl ether sulfate/AlCl3 solutions: the role of the alkyl chain length.

    PubMed

    Xu, Hui; Penfold, Jeffrey; Thomas, Robert K; Petkov, Jordan T; Tucker, Ian; Webster, John P R

    2013-10-15

    The influence of the alkyl chain length on surface multilayer formation at the air-water interface for the anionic surfactant sodium diethylene glycol monoalkyl ether sulfate, SAE2S, in the presence of Al(3+) multivalent counterions, in the form of AlCl3, is described. In the absence of electrolyte, the saturated monolayer adsorption is determined by the headgroup geometry and is independent of the alkyl chain length. In the presence of Al(3+) counterions, surface multilayer formation occurs, due to the strong SAE2S/Al(3+) binding and complexation. The neutron reflection data show that the alkyl chain length of the surfactant has a significant impact upon the evolution of the surface multilayer structure with surfactant and AlCl3 concentration. Increasing the alkyl chain length from decyl to tetradecyl results in the surface multilayer formation occurring at lower surfactant and AlCl3 concentrations. At the short alkyl chain lengths, decyl and dodecyl, the regions of multilayer formation with a small number of bilayers are increasingly extended with decreasing alkyl chain length. For the alkyl chain lengths of tetradecyl and hexadecyl, the surface behavior is further affected by decreases in the surfactant solubility in the presence of AlCl3, and this ultimately dominates the surface behavior at the longer alkyl chain lengths.

  10. Characterization of Ti6Al7Nb alloy foams surface treated in aqueous NaOH and CaCl2 solutions.

    PubMed

    Bütev, Ezgi; Esen, Ziya; Bor, Şakir

    2016-07-01

    Ti6Al7Nb alloy foams having 53-73% porosity were manufactured via evaporation of magnesium space holders. A bioactive 1µm thick sodium hydrogel titanate layer, NaxH2-xTiyO2y+1, formed after 5M NaOH treatment, was converted to crystalline sodium titanate, Na2TiyO2y+1, as a result of post-heat treatment. On the other hand, subsequent CaCl2 treatment of NaOH treated specimens induced calcium titanate formation. However, heat treatment of NaOH-CaCl2 treated specimens led to the loss of calcium and disappearance of the titanate phase. All of the aforementioned surface treatments reduced yield strengths due to the oxidation of the cell walls of the foams, while elastic moduli remained mostly unchanged. Accordingly, equiaxed dimples seen on the fracture surfaces of as-manufactured foams turned into relatively flat and featureless fracture surfaces after surface treatments. On the other hand, Ca- and Na-rich coating preserved their mechanical stabilities and did not spall during fracture. The relation between mechanical properties of foams and macro-porosity fraction were found to obey a power law. The foams with 63 and 73% porosity met the desired biocompatibility requirements with fully open pore structures and elastic moduli similar to that of bone. In vitro tests conducted in simulated body fluid (SBF) showed that NaOH-heat treated surfaces exhibit the highest bioactivity and allow the formation of Ca-P rich phases having Ca/P ratio of 1.3 to form within 5 days. Although Ca-P rich phases formed only after 15 days on NaOH-CaCl2 treated specimens, the Ca/P ratio was closer to that of apatite found in bone. PMID:26807769

  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. Nature of M-Ga bonds in dihalogallyl complexes (η5-C5H5)(Me3P)2M(GaX2) (M = Fe, Ru, Os) and (η5-C5H5)(OC)2Fe(GaX2) (X = Cl, Br, I): a DFT study.

    PubMed

    Pandey, Krishna K; Patidar, Pankaj; Aldridge, Simon

    2010-11-18

    Density functional theory (DFT) calculations have been performed on the terminal dihalogallyl complexes of iron, ruthenium, and osmium (η(5)-C(5)H(5))(Me(3)P)(2)M(GaX(2)) (M = Fe, Ru, Os; X = Cl, Br, I) and (η(5)-C(5)H(5))(OC)(2)Fe(GaX(2)) (X = Cl, Br, I) at the BP86/TZ2P/ZORA level of theory. On the basis of analyses suggested by Pauling, the M-Ga bonds in all of the dihalogallyl complexes are shorter than M-Ga single bonds; moreover, on going from X = Cl to X = I, the optimized M-Ga bond distances are found to increase. From the perspective of covalent bonding, however, π-symmetry contributions are, in all complexes, significantly smaller than the corresponding σ-bonding contribution, representing only 4-10% of the total orbital interaction. Thus, in these GaX(2) complexes, the gallyl ligand behaves predominantly as a σ donor, and the short M-Ga bond lengths can be attributed to high gallium s-orbital character in the M-Ga σ-bonding orbitals. The natural population analysis (NPA) charge distributions indicate that the group 8 metal atom carries a negative charge (from -1.38 to -1.62) and the gallium atom carries a significant positive charge in all cases (from +0.76 to +1.18). Moreover, the contributions of the electrostatic interaction terms (ΔE(elstat)) are significantly larger in all gallyl complexes than the covalent bonding term (ΔE(orb)); thus, the M-Ga bonds have predominantly ionic character (60-72%). The magnitude of the charge separation is greatest for dichlorogallyl complexes (compared to the corresponding GaBr(2) and GaI(2) systems), leading to a larger attractive ΔE(elstat) term and to M-Ga bonds that are stronger and marginally shorter than in the dibromo and diiodo analogues. PMID:20977253

  13. Toward precise QEC values for the superallowed 0+→0+ β decays of T=2 nuclides: The masses of Na20, Al24, P28, and Cl32

    NASA Astrophysics Data System (ADS)

    Wrede, C.; Clark, J. A.; Deibel, C. M.; Faestermann, T.; Hertenberger, R.; Parikh, A.; Wirth, H.-F.; Bishop, S.; Chen, A. A.; Eppinger, K.; García, A.; Krücken, R.; Lepyoshkina, O.; Rugel, G.; Setoodehnia, K.

    2010-05-01

    High-precision measurements of superallowed 0+→0+ β decays of T=2 nuclides such as Mg20, Si24, S28, and Ar32 can contribute to searches for physics beyond the standard model of particle physics if the QEC values are accurate to a few keV or better. As a step toward providing precise QEC values for these decays, the ground-state masses of the respective daughter nuclei Na20, Al24, P28, and Cl32 have been determined by measuring the (He3,t) reactions leading to them with the Ar36(He3,t)K36 reaction as a calibration. A quadrupole-dipole-dipole-dipole (Q3D) magnetic spectrograph was used together with thin ion-implanted carbon-foil targets of Ne20, Mg24, Si28, S32, and Ar36. The masses of Na20 and Cl32 are found to be in good agreement with the values from the 2003 Atomic Mass Evaluation (AME03) [G. Audi, A. H. Wapstra, and C. Thibault, Nucl. Phys. ANUPABL0375-947410.1016/j.nuclphysa.2003.11.003 729, 337 (2003)], and the precision has been improved by a factor of 6 in both cases. The masses of Al24 and P28 are found to be higher than the values from AME03 by 9.5 keV (3.2σ) and 11.5 keV (3.6σ), respectively, and the precision has been improved by a factor of 2.5 in both cases. The new Cl32 mass is used together with the excitation energy of its lowest T=2 level and the mass of Ar32 to derive an improved superallowed QEC value of 6087.3(22) keV for this case. The effects on quantities related to standard-model tests including the β-ν correlation coefficient a and the isospin-symmetry-breaking correction δC are examined for the A=32 case.

  14. 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).

  15. Etching Characteristics of ZnO and Al-Doped ZnO in Inductively Coupled Cl2/CH4/H2/Ar and BCl3/CH4/H2/Ar Plasmas

    NASA Astrophysics Data System (ADS)

    Lee, Hack Joo; Kwon, Bong Soo; Kim, Hyun Woo; Kim, Seon Il; Yoo, Dong-Geun; Boo, Jin-Hyo; Lee, Nae-Eung

    2008-08-01

    ZnO and Al-doped ZnO (AZO) were etched in Cl2/CH4/H2/Ar (Cl2-based) and BCl3/CH4/H2/Ar (BCl3-based), inductively coupled plasmas (ICPs) and their etching characteristics were compared by varying the Cl2/(Cl2+CH4) and BCl3/(BCl3+CH4) flow ratios, top electrode power and dc self-bias voltage (Vdc). The etch rates of both ZnO and AZO layers were higher in the Cl2-based chemistry than in the BCl3-based chemistry. The AZO and ZnO etch rates were increased and decreased, respectively, with increasing Cl2 or BCl3 flow ratio. Optical emission measurements of the radical species in the plasma and surface binding states by optical emission spectroscopy (OES) and X-ray photoelectron spectroscopy (XPS), respectively, indicated that, with increasing Cl2 or BCl3 flow ratio; the effective removal of Al in the AZO enhanced the AZO etch rate, whereas the reduced removal of Zn by the Zn(CHx)y products reduced the ZnO etch rate.

  16. 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.

  17. Depth-dependent Concentrations of Cosmogenic 10Be, 26Al, 36Cl, HEc, NEc, and ARc in the Old Woman Iron Meteorite

    NASA Astrophysics Data System (ADS)

    Lavielle, B.; Nishiizumi, K.; Marti, K.; Jeannot, J.-P.; Caffee, M. W.; Finkel, R. C.

    1995-09-01

    We report measurements of 1OBe7 26AI, 36CI, and of light noble gases in 6 samples of the type IIB Old Woman iron meteorite. The aim of this work is to study the depth dependence of the production rates of cosmogenic nuclides in iron meteorites. Old Woman is a large single mass of 2753 kg. Five samples have been taken from a slice of about 100 cm x 50 cm. One other sample was located roughly 40 cm above the center of the slice in a perpendicular direction. The distances between any two samples vary from 36.5 cm to 57.5 cm. Studies of cosmogenic nuclides in samples of known locations are very useful for the validation of models describing the production of cosmogenic nuclides in meteorites. Cosmogenic radionuclides were measured by accelerator mass spectrometry at Lawrence Livermore National Laboratory. Partial results have been reported earlier [1]. Concentrations of 4He, 21Ne and 38Ar in aliquots of the samples were determined by conventional mass spectrometry using an isotopic dilution method. The ratio 3He/4He appears to be almost constant with a value of 0.12 - ().13. This is about half the value generally observed in iron meteorites. Similar low ratios have been previously observed in some irons and in chondritic metal and reflect diffusion losses of 3H 12,31. The ratios 4He/38Ar, 4He/21Ne and 36Ar/38Ar are similar to those observed in iron meteorites indicating no significant losses of 4He. The measured ratio S = 4He/21Ne which represents one of the best indicators of shielding depth in iron meteorites, varies from 310 to 375 in samples from the slice. By using this as a shielding parameter, profiles were obtained for the different nuclides investigated in this work. Systematic decreases from the surface to the center of the meteorite are observed and the center of the meteoroid can be determined. As expected from nuclear systematics, the ratio 36Cl/36Ar is almost constant. The ratio 36Cl/10Be is relatively constant with a mean value of 4.7 indicating that the

  18. Pulsed-Field Ultrasonic Experiments in the Quasi-2D Antiferromagnet Cs2CuBr4

    NASA Astrophysics Data System (ADS)

    Wolf, B.; Cong, P. T.; Krüger, N.; Ritter, F.; Assmus, W.; Lang, M.

    2013-03-01

    The magnetic insulators Cs2CuCl4 and Cs2CuBr4 are model systems for a frustrated quasi-two-dimensional triangular-lattice spin-1/2 Heisenberg antiferromagnet with a weak interlayer coupling. The quasi-two-dimensional character manifests itself in a broad maximum at T max in the magnetic susceptibility, which for Cs2CuCl4 has been found to mark the upper bound for a spin-liquid regime (R. Coldea et al. in Phys. Rev. B 68:134424, 2003). Motivated by the observation of characteristic B 2 dependencies in the elastic constants and ultrasound attenuation in the spin-liquid regime for this material, we look for corresponding signatures in the related Cs2CuBr4 compound at low temperatures T≤4.2 K and fields B≤50 T. We observe a softening of the elastic constant up to B s ˜32 T ( B∥ a) and a maximum in the sound attenuation at 0.86 B s . Both quantities exhibit the same characteristic B 2 dependence as found for Cs2CuCl4, suggesting the existence of a spin-liquid phase in Cs2CuBr4 as well.

  19. 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.

  20. 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

  1. 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

    2004-04-01

    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.

  2. A novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} for near UV white light-emitting diodes

    SciTech Connect

    Yang, Zhigang; Zhao, Zhengyan; Shi, Yurong; Wang, Yuhua

    2013-10-15

    Graphical abstract: - Highlights: • Novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} was prepared by solid-state reaction. • Excitation spectra suggested an obvious absorption in near-ultraviolet region. • Under 392 nm excitation, the phosphors exhibited a red emission at 614 nm. • Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} could be potentially applied in near UV white LEDs. - Abstract: A novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} was synthesized using a solid-state reaction method, and its luminescence characteristics and charge compensators effect (Li{sup +}, Na{sup +}, K{sup +}) were investigated. The excitation spectra showed a obvious absorption in near-ultraviolet region. Under 392 nm excitation, the phosphors exhibited an intense red emission at 614 nm. The Commission Internationale de l’Eclairage (CIE) chromaticity coordinates and quantum efficiency (QE) were (0.65, 0.35) and 62.3%, respectively. The good color saturation, high quantum efficiency and small thermal-quenching properties indicate that Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} could be potentially applied in near UV white light-emitting diodes.

  3. Multifunctional effect of Al2O3, SiO2 and CaO on the volatilization of PbO and PbCl2 during waste thermal treatment.

    PubMed

    Wang, Si-Jia; He, Pin-Jing; Shao, Li-Ming; Zhang, Hua

    2016-10-01

    Minerals including Al2O3, SiO2 and CaO are predominant matrixes in waste, and are thought to facilitate lead (Pb) emission control. This study distinguished the inhibition of each mineral on common stable Pb-containing compounds, including highly volatile PbCl2 and less volatile PbO. Al2O3 can lower the volatilization temperature of Pb by 29 °C due to the generation of a eutectic compound and play a minor but non-negligible role in reducing Pb volatilization. The most conspicuous inhibition effect was exerted by SiO2 and a mixture of Al2O3 and SiO2, which completely integrated PbO into the glass phase at 690 °C and prohibited its migration. In contrast, SiO2 had no significant inhibition on volatile PbCl2. CaO inhibited PbO volatilization in the absence of oxygen by controlling its diffusion, while it converted PbO to Ca2PbO4 in the presence of oxygen, thus controlling Pb diffusion and decreasing the Pb volatilization ratio and rate. The influence of CaO on PbCl2 was complex because CaO can convert PbCl2 to PbO with formation of CaCl2, and CaCl2 can also be a Cl-donor for PbO. The roles of mineral matrixes in Pb conversion were shown to be important for Pb emission control. PMID:27434254

  4. Multifunctional effect of Al2O3, SiO2 and CaO on the volatilization of PbO and PbCl2 during waste thermal treatment.

    PubMed

    Wang, Si-Jia; He, Pin-Jing; Shao, Li-Ming; Zhang, Hua

    2016-10-01

    Minerals including Al2O3, SiO2 and CaO are predominant matrixes in waste, and are thought to facilitate lead (Pb) emission control. This study distinguished the inhibition of each mineral on common stable Pb-containing compounds, including highly volatile PbCl2 and less volatile PbO. Al2O3 can lower the volatilization temperature of Pb by 29 °C due to the generation of a eutectic compound and play a minor but non-negligible role in reducing Pb volatilization. The most conspicuous inhibition effect was exerted by SiO2 and a mixture of Al2O3 and SiO2, which completely integrated PbO into the glass phase at 690 °C and prohibited its migration. In contrast, SiO2 had no significant inhibition on volatile PbCl2. CaO inhibited PbO volatilization in the absence of oxygen by controlling its diffusion, while it converted PbO to Ca2PbO4 in the presence of oxygen, thus controlling Pb diffusion and decreasing the Pb volatilization ratio and rate. The influence of CaO on PbCl2 was complex because CaO can convert PbCl2 to PbO with formation of CaCl2, and CaCl2 can also be a Cl-donor for PbO. The roles of mineral matrixes in Pb conversion were shown to be important for Pb emission control.

  5. Kinetics of oxidation of Fe-Cr-Al alloy Characterization by electrochemical spectroscopy of impedance in a 3% medium NaCl

    NASA Astrophysics Data System (ADS)

    Chadli, H.; Retima, M.; Khenioui, Y.

    2009-11-01

    The film growths kinetic study developed on the Fe-Cr-Al alloy oxidation under ambient air has been studied due to its tremendous uses in the automobile industry, specifically in catalytic exhaust. In this work, we report on its behavior as a function of various parameters such as the temperature, the oxidation duration, elaboration mode or the substrate nature and geometry. It has been shown that the growth, the morphology or the adherence of the formed layers are strongly affected by these parameters. At high temperature (900-1100 ∘C), the formed protective film for the materials studied in this work is primarily consisted of alumina. Below these temperatures, several phases may coexist, namely, the γ phase and the θ phase. The extension of this alloy application has led us to perform spectroscopic measurements of electrochemical impedance (SEI) in an aqueous environment 3% (NaCl). These measurements have shown that sane coatings preserve excellent insulating properties and the corrosion risks are related to defects in the layers while are formed.

  6. 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.

  7. Chemical thermodynamic models to represent the extraction of gallium in the system GaCl/sub 3/-AlCl/sub 3/-HCl-H/sub 2/O-tributyl phosphate

    SciTech Connect

    Judin, V.P.S.; Bautista, R.G.

    1984-12-01

    The salting-out power of this mixed electrolyte system was successfully interpreted by considering the stability of aluminum chloride complex species and calculating the concentration of free chloride ions actually available for the extraction. Three extraction mechanisms in the range of compositions examined include extraction of GaCl/sub 3/ at low H/sup +/ and salt concentrations, extraction of GaCl/sub 4//sup -/ at moderate H/sup +/ and salt concentrations, and the competition of GaCl/sub 4//sup -/ with the complex HCl.3H/sub 2/O.TBP at high H/sup +/ and salt concentrations. The extraction of gallium over a wide range of distribution ratios (K/sub D/ = 1 to 1 x 10/sup 4/) could be represented by a chemically based model taking into account the free chloride concentration and the activity coefficient of the total chloride ions.

  8. Synthesis and Reactivity of (Pentafluorophenyl)platinate(II) Complexes with Bridging 1,8-Naphthyridine (napy) and X Ligands (X = C(6)F(5), OH, Cl, Br, I, SPh). Crystal Structure of [NBu(4)][Pt(2)(&mgr;-napy)(&mgr;-OH)(C(6)F(5))(4)].CHCl(3).

    PubMed

    Ara, Irene; Casas, José M.; Forniés, Juan; Rueda, Angel J.

    1996-12-01

    By reaction of [NBu(4)](2)[Pt(2)(&mgr;-C(6)F(5))(2)(C(6)F(5))(4)] with 1,8-naphthyridine (napy), [NBu(4)][Pt(C(6)F(5))(3)(napy)] (1) is obtained. This compound reacts with cis-[Pt(C(6)F(5))(2)(THF)(2)] to give the dinuclear derivative [NBu(4)][Pt(2)(&mgr;-napy)(&mgr;-C(6)F(5))(C(6)F(5))(4)] (2). The reaction of several HX species with 2 results in the substitution of the bridging C(6)F(5) by other ligands (X) such as OH (3), Cl (4), Br (5), I (6), and SPh (7), maintaining in all cases the naphthyridine bridging ligand. The structure of 3 was determined by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system, space group P2(1)/n, with a = 12.022(2) Å, b = 16.677(3) Å, c = 27.154(5) Å, beta = 98.58(3) degrees, V = 5383.2(16) Å(3), and Z = 4. The structure was refined to residuals of R = 0.0488 and R(w) = 0.0547. The complex consists of two square-planar platinum(II) fragments sharing a naphthyridine and OH bridging ligands, which are in cis positions. The short Pt-Pt distance [3.008(1) Å] seems to be a consequence of the bridging ligands.

  9. The competition of Y⋯O and X⋯N halogen bonds to enhance the group V σ-hole interaction in the NCY⋯O=PH3 ⋯NCX and O=PH3 ⋯NCX⋯NCY (X, Y=F, Cl, and Br) complexes.

    PubMed

    Li, Wei; Zeng, Yanli; Li, Xiaoyan; Sun, Zheng; Meng, Lingpeng

    2015-07-01

    The positive electrostatic potentials (ESP) outside the σ-hole along the extension of OP bond in OPH3 and the negative ESP outside the nitrogen atom along the extension of the CN bond in NCX could form the Group V σ-hole interaction OPH3 ⋯NCX. In this work, the complexes NCY⋯OPH3 ⋯NCX and OPH3 ⋯NCX⋯NCY (X, YF, Cl, Br) were designed to investigate the enhancing effects of Y⋯O and X⋯N halogen bonds on the P⋯N Group V σ-hole interaction. With the addition of Y⋯O halogen bond, the VS, max values outside the σ-hole region of OPH3 becomes increasingly positive resulting in a stronger and more polarizable P⋯N interaction. With the addition of X⋯N halogen bond, the VS, min values outside the nitrogen atom of NCX becomes increasingly negative, also resulting in a stronger and more polarizable P⋯N interaction. The Y⋯O halogen bonds affect the σ-hole region (decreased density region) outside the phosphorus atom more than the P⋯N internuclear region (increased density region outside the nitrogen atom), while it is contrary for the X⋯N halogen bonds.

  10. Intense violet-blue-emitting Ba(2)AlB(4)O(9)Cl:Eu(2+) phosphors for applications in fluorescent lamps and ultraviolet-light-emitting diodes.

    PubMed

    Kuo, Te-Wen; Huang, Chien-Hao; Chen, Teng-Ming

    2010-08-01

    We synthesized a violet-blue phosphor Ba(2)AlB(4)O(9)Cl:Eu(2+) with a solid-state reaction. The excitation and emission spectra of this phosphor showed that all were broadband due to 4f(7)-4f(6)d(1) transitions of Eu(2+). The phosphors with different Eu(2+) concentrations presented violet-blue luminescence for ultraviolet [(UV) 250-390nm] excitation. The optimum concentration of Eu(2+) in Ba(2)AlB(4)O(9)Cl:Eu(2+) is determined to be 6mol.%. The luminous efficiency was found to be 8.1lm/W for the violet-blue fluorescent lamp and 3.2lm/W for the violet-blue phosphor-converted light-emitting diode, respectively. Ba(2)AlB(4)O(9)Cl:Eu(2+) would be a promising phosphor for converting the UV radiation to violet-blue emission for a novel high light-conversion efficiency phototherapy illuminator.

  11. 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

  12. Synthetic, Spectroscopic, and Electrochemical Studies of the Isomerically-Rich [M(CO)(2)(P(2)P')X](+/0) (M = Mn, Re; X = Cl, Br; P(2)P' = eta(3)-Ph(2)P(CH(2))(2)P(Ph)(CH(2))(2)PPh(2)) System: Structural Characterization of a Novel Pair of Diastereoisomers of cis,mer-Re(CO)(2)(P(2)P')Cl.

    PubMed

    Bond, Alan M.; Colton, Ray; Gable, Robert W.; Mackay, Maureen F.; Walter, Jacky N.

    1997-03-12

    Reaction of Mn(CO)(5)X (X = Cl, Br) with Ph(2)P(CH(2))(2)P(Ph)(CH(2))(2)PPh(2) (P(2)P') in refluxing xylene led to the formation of isomerically pure cis,mer-Mn(CO)(2)(eta(3)-P(2)P')X. Cyclic voltammograms in dichloromethane (0.1 M Bu(4)NPF(6)) show a reversible one-electron oxidation (process 1, E(1/2) = 0.142 V) to give cis,mer-[Mn(CO)(2)(P(2)P')X](+). However, in acetone (0.1 M Bu(4)NPF(6)) at room temperature, process 1 is not reversible and an additional redox process 4 (E(1/2) = 0.048 V) is observed. Process 4 is not observed at low temperatures, and at higher temperatures in acetone it merges with process 1 and also a new reversible redox couple (process 5, E(1/2) = -0.411 V) appears. A combination of electrolyses, chemical oxidation, and subsequent reduction, coupled with IR and (31)P NMR spectroscopies and electrospray mass spectrometry (ESMS), is used to show that processes 1, 4, and 5 are all associated with redox and interconversion reactions of different isomers of Mn(CO)(2)(P(2)P')X and [Mn(CO)(2)(P(2)P')X](+). Other irreversible processes due to oxidation of the different isomers of [Mn(CO)(2)(P(2)P')X](+) are observed at very positive potentials. Reaction between Re(CO)(5)X and P(2)P' in refluxing mesitylene gives a soluble product and a small amount of precipitate. The major soluble product was identified as cis,mer-Re(CO)(2)(P(2)P')X, and the oxidative chemistry is similar to that of the manganese analogues. The precipitate consists of five compounds, one of which was cis,mer-Re(CO)(2)(P(2)P')X. The new compounds A-D were identified as follows: A is cis,mer-{Re(CO)(2)(P(2)P')X}(2), a dimeric species with bridging P(2)P' ligands. The spectroscopic data for B indicated that it was a form of cis,mer-Re(CO)(2)(P(2)P')X, but not the same as the major product. Compound C is cis,fac-Re(CO)(2)(P(2)P')X, and compound D was shown to be fac-[Re(CO)(3)(P(2)P')]X. The crystal structures of cis,mer-Re(CO)(2)(P(2)P')Cl(I) and cis,mer-Re(CO)(2)(P(2)P')Cl(II) show

  13. Pb(3)Te(2)O(6)Br(2).

    PubMed

    Weil, Matthias; Stöger, Berthold

    2010-01-16

    Single crystals of the title compound, trilead(II) bis-[tellurate(IV)] dibromide, have been grown under hydro-thermal conditions. The structure is isotypic with that of the chloride analogue, Pb(3)Te(2)O(6)Cl(2), and consists of three Pb, two Te, two Br and four O atoms in the asymmetric unit. Except for two of the O atoms, all atoms are located on mirror planes. The Pb(3)Te(2)O(6)Br(2) structure can be described as being built up from (∞) (2)[Pb(3)Te(2)O(6)](2+) layers extending parallel to (20) and Br(-) anions between the layers. Cohesion of the structure is accomplished through Pb-Br contacts of two of the three lead atoms, leading to highly asymmetric coordination polyhedra. The lone-pair electrons of both Te(IV) and Pb(II) atoms are stereochemically active and point towards the anionic halide layers.

  14. Atmospheric test of the J(BrONO2)/kBrO+NO2 ratio: implications for total stratospheric Bry and bromine-mediated ozone loss

    NASA Astrophysics Data System (ADS)

    Kreycy, S.; Camy-Peyret, C.; Chipperfield, M. P.; Dorf, M.; Feng, W.; Hossaini, R.; Kritten, L.; Werner, B.; Pfeilsticker, K.

    2013-07-01

    We report on time-dependent O3, NO2 and BrO profiles measured by limb observations of scattered skylight in the stratosphere over Kiruna (67.9° N, 22.1° E) on 7 and 8 September 2009 during the autumn circulation turn-over. The observations are complemented by simultaneous direct solar occultation measurements around sunset and sunrise performed aboard the same stratospheric balloon payload. Supporting radiative transfer and photochemical modelling indicate that the measurements can be used to constrain the ratio J(BrONO2)/kBrO+NO2, for which at T = 220 ± 5 K an overall 1.7 (+0.4 -0.2) larger ratio is found than recommended by the most recent Jet Propulsion Laboratory (JPL) compilation (Sander et al., 2011). Sensitivity studies reveal the major reasons are likely to be (1) a larger BrONO2 absorption cross-section σBrONO2, primarily for wavelengths larger than 300 nm, and (2) a smaller kBrO+NO2 at 220 K than given by Sander et al. (2011). Other factors, e.g. the actinic flux and quantum yield for the dissociation of BrONO2, can be ruled out. The observations also have consequences for total inorganic stratospheric bromine (Bry) estimated from stratospheric BrO measurements at high NOx loadings, since the ratio J(BrONO2)/kBrO+NO2 largely determines the stratospheric BrO/Bry ratio during daylight. Using the revised J(BrONO2)/kBrO+NO2 ratio, total stratospheric Bry is likely to be 1.4 ppt smaller than previously estimated from BrO profile measurements at high NOx loadings. This would bring estimates of Bry inferred from organic source gas measurements (e.g. CH3Br, the halons, CH2Br2, CHBr3, etc.) into closer agreement with estimates based on BrO observations (inorganic method). The consequences for stratospheric ozone due to the revised J(BrONO2)/kBrO+NO2 ratio are small (maximum -0.8%), since at high NOx (for which most Bry assessments are made) the enhanced ozone loss by overestimating Bry is compensated for by the suppressed ozone loss due to the underestimation

  15. Dynamic and static behavior of hydrogen bonds of the X-H···π type (X = F, Cl, Br, I, RO and RR'N; R, R' = H or Me) in the benzene π-system, elucidated by QTAIM dual functional analysis.

    PubMed

    Sugibayashi, Yuji; Hayashi, Satoko; Nakanishi, Waro

    2015-11-21

    Dynamic and static behavior of the X-H-*-π interactions in X-H-*-π(C6H6) (X = F, Cl, Br, I, HO, MeO, H2N, MeHN and Me2N) is elucidated by QTAIM-DFA (QTAIM dual functional analysis), which we proposed recently, as the first step to clarify various types of X-H-*-π interactions. The asterisk * emphasizes the existence of the bond critical point (BCP) on the interaction in question. Total electron energy densities (H(b)(r(c))) are plotted versus H(b)(r(c)) - V(b)(r(c))/2 [=(ℏ(2)/8m)∇(2)ρ(b)(r(c))] at BCPs in QTAIM-DFA, where V(b)(r(c)) are potential energy densities at BCPs. In our treatment, data for the perturbed structures around the fully optimized ones are employed, in addition to those for the fully optimized structures. Data from the fully optimized structures are analyzed by the polar coordinate (R, θ) representation. Each plot for an interaction, containing data from the perturbed structures, shows a specific curve, which provides important information. The plot is expressed by (θ(p), κ(p)): θ(p) corresponds to the tangent line of the plot and κ(p) is the curvature. θ and θ(p) are measured from the y-axis and the y-direction, respectively. While (R, θ) correspond to the static nature, (θ(p), κ(p)) represent the dynamic nature of interactions. The nature of the X-H-*-π(C6H6) interactions is well specified by (R, θ) and (θ(p), κ(p)). All interactions, examined in this work, are classified by the pure closed shell interactions and predicted to have the van der Waals nature.

  16. Pathways for the OH + Br2 → HOBr + Br and HOBr + Br → HBr + BrO Reactions.

    PubMed

    Wang, Hongyan; Qiu, Yudong; Schaefer, Henry F

    2016-02-11

    The OH radical reaction with Br2 and the subsequent reaction HOBr + Br are of exceptional importance to atmospheric chemistry and environmental chemistry. The entrance complex, transition state, and exit complex for both reactions have been determined using the coupled-cluster method with single, double, and perturbative triple excitations CCSD(T) with correlation consistent basis sets up to size cc-pV5Z and cc-pV5Z-PP. Coupled cluster effects with full triples (CCSDT) and full quadruples (CCSDTQ) are explicitly investigated. Scalar relativistic effects, spin-orbit coupling, and zero-point vibrational energy corrections are evaluated. The results from the all-electron basis sets are compared with those from the effective core potential (ECP) pseudopotential (PP) basis sets. The results are consistent. The OH + Br2 reaction is predicted to be exothermic 4.1 ± 0.5 kcal/mol, compared to experiment, 3.9 ± 0.2 kcal/mol. The entrance complex HO···BrBr is bound by 2.2 ± 0.2 kcal/mol. The transition state lies similarly well below the reactants OH + Br2. The exit complex HOBr···Br is bound by 2.7 ± 0.6 kcal/mol relative to separated HOBr + Br. The endothermicity of the reaction HOBr + Br → HBr + BrO is 9.6 ± 0.7 kcal/mol, compared with experiment 8.7 ± 0.3 kcal/mol. For the more important reverse (exothermic) HBr + BrO reaction, the entrance complex BrO···HBr is bound by 1.8 ± 0.6 kcal/mol. The barrier for the HBr + BrO reaction is 6.8 ± 0.9 kcal/mol. The exit complex (Br···HOBr) for the HBr + BrO reaction is bound by 1.9 ± 0.2 kcal/mol with respect to the products HOBr + Br. PMID:26766412

  17. Influences of the substituents on the M-M bonding in Cp4Al4 and Cp2M2X2 (M = B, Al, Ga; Cp = C5H5, X = halogen).

    PubMed

    Lu, Feifei; Li, Xiaoyan; Sun, Zheng; Zeng, Yanli; Meng, Lingpeng

    2015-08-21

    Although the geometries of CpAl4 (Cp* = C5Me5) and Cp4Al4 (Cp = C5H5) are similar, CpAl4 is more stable than Cp4Al4. CpAl2I2 is the first complex involving an Al(ii)-Al(ii) bond to be supported by Cp-type ligands. In this work, the stability of CpAl4 and Cp4Al4 (Cp = C5H5), the nature of M-M bonding in Cp2M2X2 (M = B, Al, and Ga), and the influences of the X atom on the M-M bonds have been analyzed and compared within the framework of the atoms in molecules (AIM) theory, electron localization function (ELF), energy decomposition analysis (EDA), and natural bond orbital (NBO) analysis. The calculated results show that CpAl4 is more stable than Cp4Al4 because of HH interactions between the methyl groups on the same and different Cp rings and not because of the Al-Al bonds. In Cp2M2X2, the B-B bond is stronger than the Al-Al and Ga-Ga bonds. The B-B bond is most consistent with covalent bonding, whereas the Al-Al and Ga-Ga bonds are more consistent with metallic bonding. The strengths of the B-B bond increase in the sequence X = F, Cl, Br, and I, whereas the Al-Al and Ga-Ga bonds decrease in the sequence X = F, Cl, Br, and I. The different change tendencies arise from the different M-M bonds and the orbital interactions between atoms X and M.

  18. X-ray photoemission analysis of chemically modified TlBr surfaces for improved radiation detectors

    DOE PAGES

    Nelson, A. J.; Voss, L. F.; Beck, P. R.; Graff, R. T.; Conway, A. M.; Nikolic, R. J.; Payne, S. A.; Lee, J. -S.; Kim, H.; Cirignano, L.; et al

    2013-01-12

    We subjected device-grade TlBr to various chemical treatments used in room temperature radiation detector fabrication to determine the resulting surface composition and electronic structure. As-polished TlBr was treated separately with HCl, SOCl2, Br:MeOH and HF solutions. High-resolution photoemission measurements on the valence band electronic structure and Tl 4f, Br 3d, Cl 2p and S 2p core lines were used to evaluate surface chemistry and shallow heterojunction formation. Surface chemistry and valence band electronic structure were correlated with the goal of optimizing the long-term stability and radiation response.

  19. 3c/4e [small sigma, Greek, circumflex]-type long-bonding competes with ω-bonding in noble-gas hydrides HNgY (Ng = He, Ne, Ar, Kr, Xe, Rn; Y = F, Cl, Br, I): a NBO/NRT perspective.

    PubMed

    Zhang, Guiqiu; Li, Hong; Weinhold, Frank; Chen, Dezhan

    2016-03-21

    Noble-gas hydrides HNgY are frequently described as a single ionic form (H-Ng)(+)Y(-). We apply natural bond orbital (NBO) and natural resonance theory (NRT) analyses to a series of noble-gas hydrides HNgY (Ng = He, Ne, Ar, Kr, Xe, Rn; Y = F, Cl, Br, I) to gain quantitative insight into the resonance bonding of these hypervalent molecules. We find that each of the studied species should be better represented as a resonance hybrid of three leading resonance structures, namely, H-Ng(+ -):Y (I), H:(- +)Ng-Y (II), and H^Y (III), in which the "ω-bonded" structures I and II arise from the complementary donor-acceptor interactions nY → σ*HNg and nH → σ*NgY, while the "long-bond" ([small sigma, Greek, circumflex]-type) structure III arises from the nNg → [small sigma, Greek, circumflex]*HY/[small sigma, Greek, circumflex]HY interaction. The bonding for all of the studied molecules can be well described in terms of the continuously variable resonance weightings of 3c/4e ω-bonding and [small sigma, Greek, circumflex]-type long-bonding motifs. Furthermore, we find that the calculated bond orders satisfy a generalized form of "conservation of bond order" that incorporates both ω-bonding and long-bonding contributions [viz., (bHNg + bNgY) + bHY = bω-bonding + blong-bonding = 1]. Such "conservation" throughout the title series implies a competitive relationship between ω-bonding and [small sigma, Greek, circumflex]-type long-bonding, whose variations are found to depend in a chemically reasonable manner on the electronegativity of Y and the outer valence-shell character of the central Ng atom. The calculated bond orders are also found to exhibit chemically reasonable correlations with bond lengths, vibrational frequencies, and bond dissociation energies, in accord with Badger's rule and related empirical relationships. Overall, the results provide electronic principles and chemical insight that may prove useful in the rational design of noble-gas hydrides of

  20. Reactive halogens (BrO and OClO) detected in the plume of Soufrière Hills Volcano during an eruption hiatus

    NASA Astrophysics Data System (ADS)

    Donovan, Amy; Tsanev, Vitchko; Oppenheimer, Clive; Edmonds, Marie

    2014-08-01

    plumes are sites of dynamic chemistry involving halogen gases. Here we present new data on the relative abundances of SO2, BrO and OClO gases emitted from Soufrière Hills Volcano [SHV). They were collected during an eruptive hiatus but during sustained degassing at this halogen-rich volcano. By comparison with data from a previous study during an eruptive phase and application of the data and modeling of Villemant et al. (2008), we suggest that, after consideration of errors, either the rate of HBr conversion to BrO is variable, ranging from ˜30% to ˜15%, and/or the relative partitioning of Cl and Br into the gas phase from the melt changes according to eruptive activity. We examine the potential implications of this for fluid-melt partitioning, and compare our results with data from the experimental literature. Our work contributes toward understanding the controls on the BrO/SO2 ratio for volcano monitoring purposes; the changes in plume chemistry with regard to bromine at the onset of lava extrusion may be large and rapid. OClO was detected in the plume at SHV for the first time. This species has only previously been detected in emissions from Mount Etna (using ground-based methods) and from Puyehue Cordon Caulle (using satellite-based methods). No HCHO or NOy species were detected in the spectra.

  1. Redox routes to substitution of aluminum(III): synthesis and characterization of (IP-)2AlX (IP = α-iminopyridine, X = Cl, Me, SMe, S2CNMe2, C≡CPh, N3, SPh, NHPh).

    PubMed

    Myers, Thomas W; Holmes, Alexandra L; Berben, Louise A

    2012-08-20

    Redox active ligands are shown to facilitate a variety of group transfer reactions at redox inert aluminum(III). Disulfides can be used as a two-electron group transfer reagent, and we show that (IP(-))(2)AlSR can be formed by reaction of [(THF)(6)Na][(IP(2-))(2)Al] (1c) with disulfides RSSR (where X = C(S)NMe(2), 4; SMe, 5). In a more general redox route to substitution of aluminum bis(iminopyridine) complexes, we report zinc(II) salts as a group transfer reagent. Reaction of [((R)IP(2-))(2)Al](-) (R = H, 1c; Me, 1d) with ZnX(2) affords ((R)IP(-))(2)AlX (where IP = iminopyridine, R = H, and X = Cl, 2; CCPh, 6; N(3), 7; SPh, 8; or R = Me and X = NHPh, 9). Single crystal X-ray diffraction analysis of the complexes reveal that each of the five coordinate complexes reported here has a trigonal bipyramidal geometry with τ = 0.668 - 0.858. We observed a correlation between the greatest deviations from ideal trigonal bipyramidal symmetry (lowest τ values), the bond lengths consistent with smallest degree of ligand reduction, and the least polarizable X ligand in (IP(-))(2)AlX. Complex 4 is six-coordinate and is best described as distorted octahedral. Variable temperature magnetic susceptibility measurements indicate that each of the complexes 3-9 has a biradical electronic structure similar to previously reported 2. Magnetic exchange coupling constants in the range J = -94 to -212 cm(-1) were fit to the data for 2-9 to describe the energy of antiferromagnetic interaction between ligand radicals assuming a spin Hamiltonian of the form Ĥ = -2JŜ(L(1))·Ŝ(L(2)). The strongest coupling occurs when the angle between the ligand planes is smallest, presumably to afford good overlap with the Al-X σ* orbital. Electrochemical properties of the complexes were probed using cyclic voltammetry and each of 3-9 displayed a reversible two-electron reduction and two quasi-reversible one-electron oxidation processes. The energy of the ligand based redox processes for 2-9 differ by

  2. Self-Induced Surface Texturing of AL2O3 by Means of Inductively Coupled Plasma Reactive Ion Etching in CL2 Chemistry

    NASA Astrophysics Data System (ADS)

    Batoni, Paolo; Stokes, Edward B.; Shah, Trushant K.; Hodge, Michael D.; Suleski, Thomas J.

    2007-06-01

    In this work we investigate a pseudo-random surface texturing technique of sapphire by means of inductively coupled plasma reacting ion etching in chlorine chemistry, for which no sophisticated lithographic process is required. Such a surface texturing technique, which we believe offers indicative promise for enhanced light extraction in deep ultraviolet light-emitting diodes has allowed us to texture sapphire samples having a surface larger than 1 cm2 with controlled structures. Fabrication parameters have been characterized, and textured Al2O3 surfaces having submicron features, and nano-scale periodicity have been obtained. Performance, and characterization of our textured Al2O3 surfaces is the hinge of addition work in progress.

  3. Activation of C-Cl by ground-state aluminum atoms: an EPR and DFT investigation.

    PubMed

    Joly, Helen A; Newton, Trevor; Myre, Maxine

    2012-01-01

    The reaction of ground-state Al atoms with dichloromethane (CH(2)Cl(2)) in an adamantane matrix at 77 K yielded two mononuclear Al species. The magnetic parameters, extracted from the axial EPR spectrum of Species A/A' (g(1) = 2.0037, g(2) = g(3) = 2.0030, a(Al,1) = 1307 MHz, a(Al,2) = a(Al,3) = 1273 MHz, a(35Cl) = 34 MHz and a(37Cl) = 28 MHz) were assigned to the Al-atom insertion product, ClCH(2)AlCl. Density functional theory (DFT) calculations of the values of the Al and Cl hyperfine interaction (hfi) of the Cl(1)-Cl(2)gauche conformer were in close agreement with the experimental values of ClCH(2)AlCl. The second species, B/B', had identical magnetic parameters to those of ClCH(2)AlCl with the exception that the Al hfi was 15% smaller. Coordination of a ligand, possessing a lone pair of electrons, to the Al atom of the insertion product, [ClCH(2)AlCl]:X, could cause the a(Al) to decrease by 15%. Alternatively, it is possible that the Cl(1)-Cl(2) anti conformer of ClCH(2)AlCl is also isolated in the matrix. Support for the spectral assignments is given by calculation of the nuclear hfi of [ClCH(2)AlCl]:H(2)O and the Cl(1)-Cl(2) anti conformer of ClCH(2)AlCl using a DFT method. The potential energy hypersurface for an Al atom approaching CH(2)Cl(2), calculated at the B3LYP level, suggests that Al atom abstraction of Cl forming AlCl and CH(2)Cl is favoured in the gas phase. When produced in a matrix, the close proximity of AlCl and CH(2)Cl could account for the formation of ClCH(2)AlCl. EPR evidence was also found for the formation of the CHCl(2) radical. PMID:22086441

  4. Sr{sub 3}Al{sub 2}O{sub 5}Cl{sub 2}:Ce{sup 3+},Eu{sup 2+}: A potential tunable yellow-to-white-emitting phosphor for ultraviolet light emitting diodes

    SciTech Connect

    Song Yanhua; Jia Guang; Yang Mei; Huang Yeju; You Hongpeng; Zhang Hongjie

    2009-03-02

    The Sr{sub 3}Al{sub 2}O{sub 5}Cl{sub 2}:Ce{sup 3+},Eu{sup 2+} phosphors were prepared by solid state reaction. The obtained phosphors exhibit a strong absorption in the UV-visible region and have two intense emission bands at 444 and 609 nm. The energy transfer from the Ce{sup 3+} to Eu{sup 2+} ions was observed, and the critical distance has been estimated to be about 24.5 A by spectral overlap method. Furthermore, the developed phosphors can generate lights from yellow-to-white region under the excitation of UV radiation by appropriately tuning the activator content, indicating that they have potential applications as an UV-convertible phosphor for white light emitting diodes.

  5. Cl- sensitive biosensor used electrolyte-solution-gate diamond FETs.

    PubMed

    Song, Kwang-Soup; Sakai, Toshikatsu; Kanazawa, Hirofumi; Araki, Yuta; Umezawa, Hitoshi; Tachiki, Minoru; Kawarada, Hiroshi

    2003-11-15

    We have investigated the electrolyte-solution-gate field effect transisitors (SGFETs) used hydrogen terminated (H-terminated) or partially oxygen terminated (O-terminated) polycrystalline diamond surface in the Cl- and Br- ionic solutions. The H-terminated channel SGFETs are insensitive to pH values in electrolyte solutions. The threshold voltages of the diamond SGFETs shift according to the density of Cl- and Br- ions about 30 mV/decade. One of the attractive biomedical applications for the Cl- sensitive SGFETs is the detection of chloride density in blood or in sweat especially in the case of cystic fibrosis. The sensitivities of Cl- and Br- ions have been lost on the partially O-terminated diamond surface. These phenomena can be explained by the polarity of surface change on the H-terminated and the O-terminated surface.

  6. Non-isothermal decomposition kinetics, heat capacity and thermal safety of 37.2/44/16/2.2/0.2/0.4-GAP/CL-20/Al/N-100/PCA/auxiliaries mixture.

    PubMed

    Zhang, Jiao-Qiang; Gao, Hong-Xu; Ji, Tie-Zheng; Xu, Kang-Zhen; Hu, Rong-Zu

    2011-10-15

    The specific heat capacity (C(p)) of 37.2/44/16/2.2/0.2/0.4-GAP/CL-20/Al/N-100/PCA/auxiliaries mixture was determined with the continuous C(p) mode of microcalorimeter. The equation of C(p) with temperature was obtained. The standard molar heat capacity of GAP/CL-20/Al/N-100/PCA/auxiliaries mixture was 1.225 J mol(-1)K(-1) at 298.15K. With the help of the peak temperature (T(p)) from the non-isothermal DTG curves of the mixture at different heating rates (β), the apparent activation energy (E(k) and E(o)) and pre-exponential constant (A(K)) of thermal decomposition reaction obtained by Kissinger's method and Ozawa's method. Using density (ρ) and thermal conductivity (λ), the decomposition heat (Q(d), taking half-explosion heat), Zhang-Hu-Xie-Li's formula, the values (T(e0) and T(p0)) of T(e) and T(p) corresponding to β → 0, thermal explosion temperature (T(be) and T(bp)), adiabatic time-to-explosion (t(TIad)), 50% drop height (H(50)) of impact sensitivity, and critical temperature of hot-spot initiation (T(cr,hot spot)) of thermal explosion of the mixture were calculated. The following results of evaluating