Soft X-ray absorption spectroscopy and resonant inelastic X-ray scattering spectroscopy below 100 eV: probing first-row transition-metal M-edges in chemical complexes.

PubMed

Wang, Hongxin; Young, Anthony T; Guo, Jinghua; Cramer, Stephen P; Friedrich, Stephan; Braun, Artur; Gu, Weiwei

2013-07-01

X-ray absorption and scattering spectroscopies involving the 3d transition-metal K- and L-edges have a long history in studying inorganic and bioinorganic molecules. However, there have been very few studies using the M-edges, which are below 100 eV. Synchrotron-based X-ray sources can have higher energy resolution at M-edges. M-edge X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) could therefore provide complementary information to K- and L-edge spectroscopies. In this study, M2,3-edge XAS on several Co, Ni and Cu complexes are measured and their spectral information, such as chemical shifts and covalency effects, are analyzed and discussed. In addition, M2,3-edge RIXS on NiO, NiF2 and two other covalent complexes have been performed and different d-d transition patterns have been observed. Although still preliminary, this work on 3d metal complexes demonstrates the potential to use M-edge XAS and RIXS on more complicated 3d metal complexes in the future. The potential for using high-sensitivity and high-resolution superconducting tunnel junction X-ray detectors below 100 eV is also illustrated and discussed.

Electronic Structural Analysis of Copper(II)–TEMPO/ABNO Complexes Provides Evidence for Copper(I)–Oxoammonium Character

DOE PAGES

Walroth, Richard C.; Miles, Kelsey C.; Lukens, James T.; ...

2017-09-18

Copper/aminoxyl species are proposed as key intermediates in aerobic alcohol oxidation. Several possible electronic structural descriptions of these species are possible, and here we probe this issue by examining four crystallographically characterized Cu/aminoxyl halide complexes by Cu K-edge, Cu L 2,3- edge, and Cl K-edge X-ray absorption spectroscopy. The mixing coefficients between Cu, aminoxyl, and halide orbitals are determined via these techniques with support from density functional theory. The emergent electronic structure picture reveals that Cu coordination confers appreciable oxoammonium character to the aminoxyl ligand. The computational methodology is extended to one of the putative intermediates invoked in catalytic Cu/aminoxyl-drivenmore » alcohol oxidation reactions, with similar findings. On the whole, the results have important implications for the mechanism of alcohol oxidation and the underlying basis for cooperativity in this co- catalyst system.« less

Preparation of CuO Quantum Dots by Cost-Effective Ultrasonication Technique

NASA Astrophysics Data System (ADS)

Rathod, K. N.; Savaliya, Chirag; Babiya, K. R.; Vasvani, S. H.; Ramani, Rupeshkumar V.; Ramani, Bharat M.; Joshi, Ashvini D.; Pandya, Dhiren; Shah, N. A.; Markna, J. H.

Due to exciting size-dependent chemical and physical properties, nanoscale materials have extensive range of applications compared with microstructural particles. CuO nanoparticles are very important among transition metal oxides because of their large number of applications. Quantum dots (QDs) of CuO (copper oxide) were prepared by the innovative ultrasonication method. Ultrasonic sound is used in this synthesis method to synthesize QDs of copper oxide. Structural and optical properties were studied in this research work. X-ray diffraction was used to study the formation of structural phase CuO QDs and found to be single phasic without any impurity. Transmission electron microscopic measurements were performed to study the morphology of QDs of CuO, which confirms spherical QDs with an average diameter of ˜4nm. In optical studies, absorption spectra of the CuO were analyzed by using UV-visible spectroscopy.

Electronic structure differences between H(2)-, Fe-, Co-, and Cu-phthalocyanine highly oriented thin films observed using NEXAFS spectroscopy.

PubMed

Willey, T M; Bagge-Hansen, M; Lee, J R I; Call, R; Landt, L; van Buuren, T; Colesniuc, C; Monton, C; Valmianski, I; Schuller, Ivan K

2013-07-21

Phthalocyanines, a class of macrocyclic, square planar molecules, are extensively studied as semiconductor materials for chemical sensors, dye-sensitized solar cells, and other applications. In this study, we use angular dependent near-edge x-ray absorption fine structure (NEXAFS) spectroscopy as a quantitative probe of the orientation and electronic structure of H2-, Fe-, Co-, and Cu-phthalocyanine molecular thin films. NEXAFS measurements at both the carbon and nitrogen K-edges reveal that phthalocyanine films deposited on sapphire have upright molecular orientations, while films up to 50 nm thick deposited on gold substrates contain prostrate molecules. Although great similarity is observed in the carbon and nitrogen K-edge NEXAFS spectra recorded for the films composed of prostrate molecules, the H2-phthalocyanine exhibits the cleanest angular dependence due to its purely out-of-plane π* resonances at the absorption onset. In contrast, organometallic-phthalocyanine nitrogen K-edges have a small in-plane resonance superimposed on this π* region that is due to a transition into molecular orbitals interacting with the 3dx(2)-y(2) empty state. NEXAFS spectra recorded at the metal L-edges for the prostrate films reveal dramatic variations in the angular dependence of specific resonances for the Cu-phthalocyanines compared with the Fe-, and Co-phthalocyanines. The Cu L3,2 edge exhibits a strong in-plane resonance, attributed to its b1g empty state with dx(2)-y(2) character at the Cu center. Conversely, the Fe- and Co- phthalocyanine L3,2 edges have strong out-of-plane resonances; these are attributed to transitions into not only b1g (dz(2)) but also eg states with dxz and dyz character at the metal center.

Optical and electrical stability of viral-templated copper sulfide (Cu1.8S) films

NASA Astrophysics Data System (ADS)

Shahriar Zaman, Mohammed; Bernard Grajeda, Gabriel; Haberer, Elaine D.

2014-04-01

The optical and electrical stabilities of viral-templated non-stoichiometric copper sulfide, digenite (Cu1.8S) films were investigated. The films were composed of large agglomerates of randomly aligned Cu1.8S-coated M13 filamentous phage. Free carrier optical absorption associated with localized surface plasmon resonance (LSPR) was observed in the near infrared spectral region, and the films were electrically active, displaying a linear current-voltage relationship. Under ambient conditions, the magnitude of the LSPR absorption increased, following a power law relationship with time, and the electrical resistance of viral-templated films decreased significantly. In contrast, the resistance of films stored under low oxygen, low humidity conditions experienced a smaller reduction in electrical resistance. Changes in optical and electrical film properties under ambient conditions were associated with an increase in free carrier concentration within the copper chalcogenide material due to oxygen exposure. X-ray photoelectron spectroscopy was used to relate this increase in free carrier concentration to compositional changes on the viral-templated material surface.

Synthesis and application of a highly selective copper ions fluorescent probe based on the coumarin group

NASA Astrophysics Data System (ADS)

He, Guangjie; Liu, Xiangli; Xu, Jinhe; Ji, Liguo; Yang, Linlin; Fan, Aiying; Wang, Songjun; Wang, Qingzhi

2018-02-01

A highly selective copper ions fluorescent probe based on the coumarin-type Schiff base derivative 1 (probe) was produced by condensation reaction between coumarin carbohydrazide and 1H-indazole-3-carbaldehyde. The UV-vis spectroscopy showed that the maximum absorption peak of compound 1 appeared at 439 nm. In the presence of Cu2 + ions, the maximum peak decreased remarkably compared with other physiological important metal ions and a new absorption peak at 500 nm appeared. The job's plot experiments showed that complexes of 1:2 binding mode were formed in CH3CN:HEPES (3:2, v/v) solution. Compound 1 exhibited a strong blue fluorescence. Upon addition of copper ions, the fluorescence gradually decreased and reached a plateau with the fluorescence quenching rate up to 98.73%. The detection limit for Cu2 + ions was estimated to 0.384 ppm. Fluorescent microscopy experiments demonstrated that probe 1 had potential to be used to investigate biological processes involving Cu2 + ions within living cells.

Mononuclear nickel (II) and copper (II) coordination complexes supported by bispicen ligand derivatives: Experimental and computational studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Nirupama; Niklas, Jens; Poluektov, Oleg

2017-01-01

The synthesis, characterization and density functional theory calculations of mononuclear Ni and Cu complexes supported by the N,N’-Dimethyl-N,N’-bis-(pyridine-2-ylmethyl)-1,2-diaminoethane ligand and its derivatives are reported. The complexes were characterized by X-ray crystallography as well as by UV-visible absorption spectroscopy and EPR spectroscopy. The solid state structure of these coordination complexes revealed that the geometry of the complex depended on the identity of the metal center. Solution phase characterization data are in accord with the solid phase structure, indicating minimal structural changes in solution. Optical spectroscopy revealed that all of the complexes exhibit color owing to d-d transition bands in the visiblemore » region. Magnetic parameters obtained from EPR spectroscopy with other structural data suggest that the Ni(II) complexes are in pseudo-octahedral geometry and Cu(II) complexes are in a distorted square pyramidal geometry. In order to understand in detail how ligand sterics and electronics affect complex topology detailed computational studies were performed. The series of complexes reported in this article will add significant value in the field of coordination chemistry as Ni(II) and Cu(II) complexes supported by tetradentate pyridyl based ligands are rather scarce.« less

Optical and Morphological Characterization of Sonochemically Assisted Europium Doped Copper (I) Oxide Nanostructures

NASA Astrophysics Data System (ADS)

Cosico, J. A. M.; Ruales, P. K.; Marquez, M. C.

2017-06-01

In the age where application of nanotechnology in our society has proven to be eminent, different routes of synthesizing nanoparticles have emerged. In this study nanoparticles of cuprous oxide (Cu2O) doped with different amounts of europium was prepared by using solution precursor route approach with the aid of ultrasonic sound. Copper sulphate and europium (III) nitrate pentahydrate was used as source for copper ions and europium ions respectively. X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR) were used to elucidate the cubic crystal structure and organic impurities present on Cu2Onanoparticles. UV-Vis spectroscopy was used to determine the absorption spectrum of the nanoparticles in the wavelength range of 400nm to 700nm. The bandgap of the undoped and doped Cu2O were found to fall between 2.1eV - 2.3eV. Scanning Electron Microscopy (SEM) coupled with energy dispersive x-ray was used to observe the dendritic and rodlike morphology and the presence of europium in the synthesized Cu2O nanoparticles. The observed effect on the absorbance of Cu2O upon adding Eu and a facile way of synthesizing Cu2O nanoparticles could bring a positive impact on the production of functional devices for optoelectronic and energy applications.

Hydrogenation of CO 2 to methanol on CeO x/Cu(111) and ZnO/Cu(111) catalysts: Role of the metal-oxide interface and importance of Ce 3+ sites

DOE PAGES

Senanayake, Sanjaya D.; Ramirez, Pedro J.; Waluyo, Iradwikanari; ...

2016-01-06

The role of the interface between a metal and oxide (CeO x–Cu and ZnO–Cu) is critical to the production of methanol through the hydrogenation of CO 2 (CO 2 + 3H 2 → CH 3OH + H 2O). The deposition of nanoparticles of CeO x or ZnO on Cu(111), θ oxi < 0.3 monolayer, produces highly active catalysts for methanol synthesis. The catalytic activity of these systems increases in the sequence: Cu(111) < ZnO/Cu(111) < CeO x/Cu(111). The apparent activation energy for the CO 2 → CH 3OH conversion decreases from 25 kcal/mol on Cu(111) to 16 kcal/mol on ZnO/Cu(111)more » and 13 kcal/mol on CeO x/Cu(111). The surface chemistry of the highly active CeO x–Cu(111) interface was investigated using ambient pressure X-ray photoemission spectroscopy (AP-XPS) and infrared reflection absorption spectroscopy (AP-IRRAS). Both techniques point to the formation of formates (HCOO –) and carboxylates (CO 2 δ–) during the reaction. Our results show an active state of the catalyst rich in Ce 3+ sites which stabilize a CO 2 δ– species that is an essential intermediate for the production of methanol. Furthermore, the inverse oxide/metal configuration favors strong metal–oxide interactions and makes possible reaction channels not seen in conventional metal/oxide catalysts.« less

Probing the Electronic Structure of - and Electron-Doped High-Temperature Superconductors with Photoemission and X-Ray Absorption Spectroscopies

NASA Astrophysics Data System (ADS)

Lederman, Eli R.

1990-01-01

The electronic structures of hole- and electron -doped high temperature superconductors have been probed using x-ray absorption near-edge spectroscopy (XANES) and photoelectron emission spectroscopy (PES). These measurements have been performed on RBa_2Cu _3O_{rm 7-y} , La_{rm 2-x}Sr _{rm x}CuO _4 and Ln_{rm 2 -x}Ce_{rm x} CuO_{rm 4} for R = Y, Eu and Ln = Nd, Pr and Sm. The parameters x and y have been varied to include a range of hole and electron carrier densities and the undoped parent compounds. Previous XANES and PES results have indicated that unoccupied states of O 2p character can be associated with the carriers in the materials RBa_2 Cu_3O_{ rm 7-y} and La_{ rm 2-x}Sr_{rm x}CuO_4 and that the density of holes increases with O and Sr content, respectively. Conduction was hole-based in all known high-T_{ rm c} cuprates until the recent discovery of superconductivity in Ln_{rm 2-x}Ce_{rm x} CuO_4. Hall coefficient measurements have suggested that the carriers in this system are electrons added with Ce doping. It has been anticipated that these electron-doped materials will provide an important test for models of high temperature superconductivity. PES measurements are presented that show significant Cu 3d character in the valence band of these electron-based materials, but that the Cu^{2+} /Cu^{1+} ratio is unchanged by the level of Ce doping, indicating that doped electrons are itinerant rather than highly correlated. Resonant photoemission from the valence band indicates the presence of unoccupied O 2p states, but these holes are less abundant than in the hole-doped materials. Measurements of XANES at the O 1s edge suggest that unoccupied states of O 2p character in the electron -doped materials are not related to conduction in a simple way. The density of these holes is shown to decrease upon Ce doping and the process of reduction, despite the fact that both are necessary of superconductivity. Furthermore, whereas the O 2p holes are at E_{rm F} in the hole-doped materials, they are ~1 eV above E_{ rm F} in their electron-doped counterparts. A schematic of the band structure is proposed on the basis of these spectroscopic measurements.

Uranium speciation as a function of depth in contaminated hanford sediments--a micro-XRF, micro-XRD, and micro- and bulk-XAFS study.

PubMed

Singer, David M; Zachara, John M; Brown, Gordon E

2009-02-01

The distribution and speciation of U and Cu in contaminated vadose zone and aquifer sediments from the U.S. DOE Hanford site (300 Area) were determined using a combination of synchrotron-based micro-X-ray fluorescence (microXRF) imaging, micro-X-ray absorption near edge structure (microXANES) spectroscopy, and micro-X-ray diffraction (microXRD) techniques combined with bulk U LIII-edge X-ray absorption fine structure (XAFS) spectroscopy. Samples were collected from within the inactive North Process Pond (NPP2) at 8 ft (2.4 m, NPP2-8) depth and 12 ft (3.7 m, NPP2-12) depth in the vadose zone, and fines were isolated from turbid groundwater just below the water Table (12-14 ft, approximately 4 m, NPP2-GW). microXRF imaging, microXRD, and microXANES spectroscopy revealed two major U occurrences within the vadose and groundwater zones: (1) low to moderate concentrations of U(VI) associated with fine-textured grain coatings that were consistently found to contain clinochlore (referred to here as chlorite) observed in all three samples, and (2) U(VI)-Cu(II) hotspots consisting of micrometer-sized particles associated with surface coatings on grains of muscovite and chlorite observed in samples NPP2-8' and NPP2-GW. In the aquifer fines (NPP2-GW), these particles were identified as cuprosklodowskite (cps: Cu[(UO2)(SiO2OH)]2 x 6H2O) and metatorbernite (mtb: Cu(UO2)2(PO4)2 x 8H2O). In contrast, the U-Cu-containing particles in the vadose zone were X-ray amorphous. Analyses of U LIII-edge XAFS spectra by linear-combination fitting indicated that U speciation consisted of (1) approximately 75% uranyl sorbed to chlorite and approximately 25% mtb-like X-ray amorphous U-Cu-phosphates (8 ft depth), (2) nearly 100% sorbed uranyl (12 ft depth), and (3) approximately 70% uranyl sorbed to chlorite and approximately 30% cps/mtb (groundwater zone). These findings suggest that dissolution of U(VI)-Cu(II)-bearing solids as well as desorption of U(VI), mainly from phyllosilicates, are important persistent sources of U(VI) to the associated uranium groundwater plume in Hanford Area 300.

X-ray absorption spectroscopy and imaging of heterogeneous hydrothermal mixtures using a diamond microreactor cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulton, John L.; Darab, John G.; Hoffmann, Markus M.

2001-04-01

Hydrothermal synthesis is an important route to novel materials. Hydrothermal chemistry is also an important aspect of geochemistry and a variety of waste remediation technologies. There is a significant lack of information about the speciation of inorganic compounds under hydrothermal conditions. For these reasons we describe a high-temperature, high-pressure cell that allows one to acquire both x-ray absorption fine structure (XAFS) spectra and x-ray transmission and absorption images of heterogeneous hydrothermal mixtures. We demonstrate the utility of the method by measuring the Cu(I) speciation in a solution containing both solid and dissolved Cu phases at temperatures up to 325{sup o}C.more » X-ray imaging of the various hydrothermal phases allows micro-XAFS to be collected from different phases within the heterogeneous mixture. The complete structural characterization of a soluble bichloro-cuprous species was determined. In situ XAFS measurements were used to define the oxidation state and the first-shell coordination structure. The Cu--Cl distance was determined to be 2.12 Aa for the CuCl{sub 2}{sup -} species and the complete loss of tightly bound waters of hydration in the first shell was observed. The microreactor cell described here can be used to test thermodynamic models of solubility and redox chemistry of a variety of different hydrothermal mixtures.« less

A simple and selective resonance Rayleigh scattering-energy transfer spectral method for determination of trace neomycin sulfate using Cu2O particle as probe

NASA Astrophysics Data System (ADS)

Ouyang, Huixiang; Liang, Aihui; Jiang, Zhiliang

2018-02-01

The stable Cu2O nanocubic (Cu2ONC) sol was prepared, based on graphene oxide (GO) catalysis of glucose-Fehling's reagent reaction, and its absorption and resonance Rayleigh scattering (RRS) spectra, transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were examined. Using the as-prepared Cu2ONC as RRS probe, and coupling with the neomycin sulfate (NEO) complex reaction, a new, simple, sensitive and selective RRS-energy transfer (RRS-ET) method was established for detection of neomycin sulfate, with a linear range of 1.4-112 μM and a detection limit of 0.4 μM. The method has been applied to the detection of neomycin sulfate in samples with satisfactory results.

Effect of Annealing Temperature on Flowerlike Cu3BiS3 Thin Films Grown by Chemical Bath Deposition

NASA Astrophysics Data System (ADS)

Deshmukh, S. G.; Patel, S. J.; Patel, K. K.; Panchal, A. K.; Kheraj, Vipul

2017-10-01

For widespread application of thin-film photovoltaic solar cells, synthesis of inexpensive absorber material is essential. In this work, deposition of ternary Cu3BiS3 absorber material, which contains abundant and environmentally benign elements, was carried out on glass substrate. Flowerlike Cu3BiS3 thin films with nanoflakes as building block were formed on glass substrate by chemical bath deposition. These films were annealed at 573 K and 673 K in sulfur ambient for structural improvement. Their structure was characterized using Raman spectroscopy, as well as their surface morphological and optical properties. The x-ray diffraction profile of as-deposited Cu3BiS3 thin film revealed amorphous structure, which transformed to orthorhombic phase after annealing. The Raman spectrum exhibited a characteristic peak at 290 cm-1. Scanning electron microscopy of as-deposited Cu3BiS3 film confirmed formation of nanoflowers with diameter of around 1052 nm. Wettability testing of as-deposited Cu3BiS3 thin film demonstrated hydrophobic nature, which became hydrophilic after annealing. The measured ultraviolet-visible (UV-Vis) absorption spectra of the Cu3BiS3 thin films gave an absorption coefficient of 105 cm-1 and direct optical bandgap of about 1.42 eV after annealing treatment. Based on all these results, such Cu3BiS3 material may have potential applications in the photovoltaic field as an absorber layer.

Characterization of the Cu(Π) and Zn(Π) binding to the Amyloid-β short peptides by both the Extended X-ray Absorption Fine Structure and the Synchrotron Radiation Circular Dichroism spectroscopy

NASA Astrophysics Data System (ADS)

Zhang, Zhiyin; Sun, Shuaishuai; Xu, Jianhua; Zhang, Jing; Huang, Yan; Zhang, Bingbing; Tao, Ye

2013-04-01

Alzheimer's disease (AD) is a progressive and devastating neurodegenerative pathology, clinically characterized by dementia, cognitive impairment, personality disorders and memory loss. It is generally accepted that, misfolding of Aβ peptides is the key element in pathogenesis and the secondary structure of Aβ can be changed to major β-strand with reasons unknown yet. Many studies have shown that the misfolding may be linked with some biometals, mainly copper and zinc ions. To characterize interactions of Aβ and metal ions, we utilized both the extended X-ray fine structure spectroscopy (EXAFS) and the synchrotron radiation circular dichroism spectroscopy (SRCD). Aβ (13-22), Aβ (13-21), Aβ (E22G) and Aβ(HH-AA) were selected to study the mechanism of copper and zinc binding to Aβ. We found that Cu interaction with H13 and H14 residues led to the disappearance of the PPΠ, while the Cu binding E22 residue caused a remarkable conformation change to β-sheet enrichment. The Zn ion, in contrast, made little effect on the conformation and it coordinated to only one histidine (H residue) or not.

A rapid microwave synthesis of nitrogen-sulfur co-doped carbon nanodots as highly sensitive and selective fluorescence probes for ascorbic acid.

PubMed

Duan, Junxia; Yu, Jie; Feng, Suling; Su, Li

2016-06-01

A ultrafast one-step microwave-assisted method was developed for the synthesis of nitrogen-sulfur co-doped carbon nanodots (N,S-CDs) by using ethylenediamine as the carbon source and sulfamic acid as the surface passivation reagent. The morphology and the properties of N,S-CDs were explored by a series of techniques, such as high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis absorption and fluorescence spectroscopy. The prepared N,S-CDs exhibit bright blue photoluminescence with a high fluorescence quantum yield (FLQY) up to 28%, and high stability and excellent water solubility. A N,S-CDs-based fluorescent probe was developed for sensitive detection ascorbic acid (AA) in the presence of Cu(2+), based on the mechanism that AA reduces Cu(2+) to Cu(+), then Cu(+) quenches the fluorescence of N,S-CDs through electron or energy transfer due to the interaction between Cu(+) and thiol ligand on the N,S-CDs surface. The observed linear response concentration range was from 0.057 to 4.0μM to AA with a detection limit as low as 18nM. The probe exhibited a highly selective response toward AA even in the presence of possible interfering substances, such as uric acid and citric acid. Moreover, these promising features made the sensing system used for the analysis of human serum and urine samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Observation of confinement effects through liner and nonlinear absorption spectroscopy in cuprous oxide

NASA Astrophysics Data System (ADS)

Sekhar, H.; Rakesh Kumar, Y.; Narayana Rao, D.

2015-02-01

Cuprous oxide nano clusters, micro cubes and micro particles were successfully synthesized by reducing copper (II) salt with ascorbic acid in the presence of sodium hydroxide via a co-precipitation method. The X-ray diffraction studies revealed the formation of pure single phase cubic. Raman spectrum shows the inevitable presence of CuO on the surface of the Cu2O powders which may have an impact on the stability of the phase. Transmission electron microscopy (TEM) data revealed that the morphology evolves from nanoclusters to micro cubes and micro particles by increasing the concentration of NaOH. Linear optical measurements show that the absorption peak maximum shifts towards red with changing morphology from nano clusters to micro cubes and micro particles. The nonlinear optical properties were studied using open aperture Z-scan technique with 532 nm, 6 ns laser pulses. Samples exhibited saturable as well as reverse saturable absorption. The results show that the transition from SA to RSA is ascribed to excited-state absorption (ESA) induced by two-photon absorption (TPA) process. Due to confinement effects (enhanced band gap) we observed enhanced nonlinear absorption coefficient (βeff) in the case of nano-clusters compared to their micro-cubes and micro-particles.

An Intense Slit Discharge Source of Jet-Cooled Molecular Ions and Radicals (T(sub rot) less than 30 K)

NASA Technical Reports Server (NTRS)

Anderson, David T.; Davis, Scott; Zwier, Timothy S.; Nesbitt, David J.

1996-01-01

A novel pulsed, slit supersonic discharge source is described for generating intense jet-cooled densities of radicals (greater than 10(exp 12)/cu cm) and molecular ions (greater than 10(exp 10)/cu cm) under long absorption path (80 cm), supersonically cooled conditions. The design confines the discharge region upstream of the supersonic expansion orifice to achieve efficient rotational cooling down to 30 K or less. The collisionally collimated velocity distribution in the slit discharge geometry yields sub-Doppler spectral linewidths, which for open-shell radicals reveals spin-rotation splittings and broadening due to nuclear hyperfine structure. Application of the slit source for high-resolution, direct IR laser absorption spectroscopy in discharges is demonstrated on species such as OH, H3O(+) and N2H(+).

In-Situ Probing Plasmonic Energy Transfer in Cu(In, Ga)Se2 Solar Cells by Ultrabroadband Femtosecond Pump-Probe Spectroscopy.

PubMed

Chen, Shih-Chen; Wu, Kaung-Hsiung; Li, Jia-Xing; Yabushita, Atsushi; Tang, Shih-Han; Luo, Chih Wei; Juang, Jenh-Yih; Kuo, Hao-Chung; Chueh, Yu-Lun

2015-12-18

In this work, we demonstrated a viable experimental scheme for in-situ probing the effects of Au nanoparticles (NPs) incorporation on plasmonic energy transfer in Cu(In, Ga)Se2 (CIGS) solar cells by elaborately analyzing the lifetimes and zero moment for hot carrier relaxation with ultrabroadband femtosecond pump-probe spectroscopy. The signals of enhanced photobleach (PB) and waned photoinduced absorption (PIA) attributable to surface plasmon resonance (SPR) of Au NPs were in-situ probed in transient differential absorption spectra. The results suggested that substantial carriers can be excited from ground state to lower excitation energy levels, which can reach thermalization much faster with the existence of SPR. Thus, direct electron transfer (DET) could be implemented to enhance the photocurrent of CIGS solar cells. Furthermore, based on the extracted hot carrier lifetimes, it was confirmed that the improved electrical transport might have been resulted primarily from the reduction in the surface recombination of photoinduced carriers through enhanced local electromagnetic field (LEMF). Finally, theoretical calculation for resonant energy transfer (RET)-induced enhancement in the probability of exciting electron-hole pairs was conducted and the results agreed well with the enhanced PB peak of transient differential absorption in plasmonic CIGS film. These results indicate that plasmonic energy transfer is a viable approach to boost high-efficiency CIGS solar cells.

Trace and Essential Elements Analysis in Cymbopogon citratus (DC.) Stapf Samples by Graphite Furnace-Atomic Absorption Spectroscopy and Its Health Concern

PubMed Central

Anal, Jasha Momo H.

2014-01-01

Cymbopogon citratus (DC.) Stapf commonly known as lemon grass is used extensively as green tea and even as herbal tea ingredient across the world. Plants have the ability to uptake metals as nutrient from the soil and its environment which are so essential for their physiological and biochemical growth. Concentrations of these twelve trace elements, namely, Mg, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Mo, As, Cd, and Pb, are analysed by graphite furnace-atomic absorption spectroscopy (GF-AAS) and are compared with the permissible limits of FAO/WHO, ICMR, and NIH, USA, which are found to be within permissible limits. Toxic metals like As, Cd, and Pb, analysed are within the tolerable daily diet limit and at low concentration. PMID:25525430

Auger electron and X-ray photoelectron spectroscopic study of the biocorrosion of copper by alginic acid polysaccharide

NASA Astrophysics Data System (ADS)

Jolley, John G.; Geesey, Gill G.; Hankins, Michael R.; Wright, Randy B.; Wichlacz, Paul L.

1989-08-01

Thin films (3.4 nm) of copper on germanium substrates were exposed to 2% alginic acid polysaccharide aqueous solution. Pre- and post-exposure characterization were done by Auger electron spectroscopy and X-ray photoelectron spectroscopy. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrate. Results indicate that some of the copper was oxidized by the alginic acid solution. Some of the copper was removed from the Cu/Ge interface and incorporated into the polymer matrix. Thus, biocorrosion of copper was exhibited by the alginic acid polysaccharide.

Experimental study of copper-alkali ion exchange in glass

NASA Astrophysics Data System (ADS)

Gonella, F.; Caccavale, F.; Bogomolova, L. D.; D'Acapito, F.; Quaranta, A.

1998-02-01

Copper-alkali ion exchange was performed by immersing different silicate glasses (soda-lime and BK7) in different molten eutectic salt baths (CuSO4:Na2SO4 and CuSO4:K2SO4). The obtained optical waveguides were characterized by m-lines spectroscopy for the determination of refractive index profiles, and by secondary ion mass spectrometry for the concentration profiles of the ion species involved in the exchange process. The different oxidation states of copper inside the glass structure were studied by electron paramagnetic resonance and x-ray absorption techniques. Interdiffusion copper coefficients were also determined. The Cu-alkali exchange was observed to give rise to local structural rearrangement of the atoms in the glass matrix. The Cu+ ion was found to mainly govern the exchange process, while competition between Cu-Na and K-Na exchanges occurred when a potassium sulfate bath was used. In this case, significant waveguide modal birefringence was observed.

Preparation and characterization of polyaniline-copper composites by electrical explosion of wire.

PubMed

Liu, Aijie; Bac, Luong Huu; Kim, Jin-Chun; Liu, Lizhu

2012-07-01

Polyaniline-copper composites with a polyacrylic acid (PAA) were synthesized by electrical explosion of wire. Polyaniline (PANI) and PAA were put into the explosion medium, deionized water (DIW) and ethanol, stirred for 24 hrs and sonicated for 2 hrs. These solutions were used as base liquids for explosion process to fabricate Cu nanoparticle. Optical absorption in the UV-visible region of PANI and PANI/PAA-Cu composites was measured in a range of 200-900 nm. X-ray diffraction was used to analyze the phase of the composites. XRD pattern showed the PANI was amorphous and copper was polycrystalline. Two phases of Cu and Cu2O were formed in aqueous solution while single Cu phase was obtained in ethanol solution. Field emission scanning electron microscope was used to observe the microstructure of the composites. The synthesized composites were extensively characterized by Fourier Transform Infrared (FTIR) spectroscopy and electrical measurements.

Investigating Li 2NiO 2–Li 2CuO 2 Solid Solutions as High-Capacity Cathode Materials for Li-Ion Batteries

DOE PAGES

Xu, Jing; Renfrew, Sara; Marcus, Matthew A.; ...

2017-05-11

Li 2Ni 1–xCu xO 2 solid solutions were prepared by a solid-state method to study the correlation between composition and electrochemical performance. Cu incorporation improved the phase purity of Li 2Ni 1–xCu xO 2 with orthorhombic Immm structure, resulting in enhanced capacity. However, the electrochemical profiles suggested Cu incorporation did not prevent irreversible phase transformation during the electrochemical process, instead, it likely influenced the phase transformation upon lithium removal. By combining ex situ X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and differential electrochemical mass spectrometry (DEMS) measurements, this study elucidates the relevant phase transformation (e.g., crystal structure, local environment, andmore » charge compensation) and participation of electrons from lattice oxygen during the first cycle in these complex oxides.« less

Photoexcited Carrier Dynamics of Cu 2S Thin Films

DOE PAGES

Riha, Shannon C.; Schaller, Richard D.; Gosztola, David J.; ...

2014-11-11

Copper sulfide is a simple binary material with promising attributes for low-cost thin film photovoltaics. However, stable Cu 2S-based device efficiencies approaching 10% free from cadmium have yet to be realized. In this paper, transient absorption spectroscopy is used to investigate the dynamics of the photoexcited state of isolated Cu 2S thin films prepared by atomic layer deposition or vapor-based cation exchange of ZnS. While a number of variables including film thickness, carrier concentration, surface oxidation, and grain boundary passivation were examined, grain structure alone was found to correlate with longer lifetimes. A map of excited state dynamics is deducedmore » from the spectral evolution from 300 fs to 300 μs. Finally, revealing the effects of grain morphology on the photophysical properties of Cu 2S is a crucial step toward reaching high efficiencies in operationally stable Cu 2S thin film photovoltaics.« less

X-ray absorption spectroscopy study of annealing process on Sr1-xLaxCuO2 electron-doped cuprate thin films

NASA Astrophysics Data System (ADS)

Galdi, A.; Orgiani, P.; Sacco, C.; Gobaut, B.; Torelli, P.; Aruta, C.; Brookes, N. B.; Minola, M.; Harter, J. W.; Shen, K. M.; Schlom, D. G.; Maritato, L.

2018-03-01

The superconducting properties of Sr1-xLaxCuO2 thin films are strongly affected by sample preparation procedures, including the annealing step, which are not always well controlled. We have studied the evolution of Cu L2,3 and O K edge x-ray absorption spectra (XAS) of Sr1-xLaxCuO2 thin films as a function of reducing annealing, both qualitatively and quantitatively. By using linearly polarized radiation, we are able to identify the signatures of the presence of apical oxygen in the as-grown sample and its gradual removal as a function of duration of 350 °C Ar annealing performed on the same sample. Even though the as-grown sample appears to be hole doped, we cannot identify the signature of the Zhang-Rice singlet in the O K XAS, and it is extremely unlikely that the interstitial excess oxygen can give rise to a superconducting or even a metallic ground state. XAS and x-ray linear dichroism analyses are, therefore, shown to be valuable tools to improving the control over the annealing process of electron doped superconductors.

DNA interaction studies of new nano metal based anticancer agent: validation by spectroscopic methods

NASA Astrophysics Data System (ADS)

Tabassum, Sartaj; Sharma, Girish Chandra; Arjmand, Farukh; Azam, Ameer

2010-05-01

A new nano dimensional heterobimetallic Cu-Sn containing complex as a potential drug candidate was designed, synthesized and characterized by analytical and spectral methods. The electronic absorption and electron paramagnetic resonance parameters of the complex revealed that the Cu(II) ion exhibits a square pyramidal geometry with the two pyrazole nitrogen atoms, the amine nitrogen atom and the carboxylate oxygen of the phenyl glycine chloride ligand located at the equatorial sites and the coordinated chloride ion occupying an apical position. 119Sn NMR spectral data showed a hexa-coordinated environment around the Sn(IV) metal ion. TEM, AFM and XRD measurements illustrate that the complex could induce the condensation of CT-DNA to a particulate nanostructure. The interaction of the Cu-Sn complex with CT-DNA was investigated by UV-vis absorption and emission spectroscopy, as well as cyclic voltammetric measurements. The results indicated that the complex interacts with DNA through an electrostatic mode of binding with an intrinsic binding constant Kb = 8.42 × 104 M - 1. The Cu-Sn complex exhibits effective cleavage of pBR322 plasmid DNA by an oxidative cleavage mechanism, monitored at different concentrations both in the absence and in the presence of reducing agents.

Fabrication and electrochemical properties of activated CNF/Cu x Mn1- x Fe2O4 composite nanostructures

NASA Astrophysics Data System (ADS)

Nilmoung, Sukanya; Sonsupap, Somchai; Sawangphruk, Montree; Maensiri, Santi

2018-06-01

This work reports the fabrication and electrochemical properties of activated carbon nanofibers composited with copper manganese ferrite (ACNF/Cu x Mn1- x Fe2O4: x = 0.0, 0.2, 0.4, 0.6, 0.8) nanostructures. The obtained samples were characterized by means of X-ray diffraction, field emission scanning electron microscopy, Brunauer-Emmett-Teller analyzer, thermal gravimetric analysis, X-ray photoemission spectroscopy, and X-ray absorption spectroscopy. The supercapacitive behavior of the electrodes is tested using cyclic voltammetery, galvanostatic charge-discharge and electrochemical impedance spectroscopy. By varying ` x', the highest specific capacitance of 384 F/g at 2 mV/s using CV and 314 F/g at 2 A/g using GCD are obtained for the x = 0.2 electrode. The second one of 235 F/g at 2 mV/s using CV and 172 F/g at 2 A/g using GCD are observed for x = 0.8 electrode. The corresponding energy densities are 74 and 41 Wh/kg, respectively. It is observed that the cyclic stability of the prepared samples strongly depend on the amount of carbon, while the specific capacitance was enhanced by the sample with nearly proportional amount between carbon and CuMnFe2O4. Such results may arise from the synergetic effect between CuMnFe2O4 and ACNF.

Amperometric sensing of hydrogen peroxide using glassy carbon electrode modified with copper nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sophia, J.; Muralidharan, G., E-mail: muraligru@gmail.com

2015-10-15

In this paper, fabrication of glassy carbon electrode (GCE) modified with nano copper particles is discussed. The modified electrode has been tested for the non-enzymatic electrochemical detection of hydrogen peroxide (H{sub 2}O{sub 2}). The copper nanoparticles (Cu NPs) were prepared employing a simple chemical reduction method. The presence of Cu NPs was confirmed through UV–visible (UV–vis) absorption spectroscopy and X-ray diffraction (XRD) analysis. The size and morphology of the particles were investigated using transmission electron microscopy (TEM). The electrochemical properties of the fabricated sensor were studied via cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS). The electrochemical sensor displayedmore » excellent performance features towards H{sub 2}O{sub 2} detection exhibiting wide linear range, low detection limit, swift response time, good reproducibility and stability.« less

Mineralization and optical characterization of copper oxide nanoparticles using a high aspect ratio bio-template

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaman, Mohammed Shahriar; Haberer, Elaine D., E-mail: haberer@ucr.edu; Materials Science and Engineering Program, University of California, Riverside, California 92521

Organized chains of copper oxide nanoparticles were synthesized, without palladium (Pd) activation, using the M13 filamentous virus as a biological template. The interaction of Cu precursor ions with the negatively charged viral coat proteins were studied with Fourier transform infrared spectroscopy, transmission electron microscopy, and energy dispersive x-ray spectroscopy. Discrete nanoparticles with an average diameter of 4.5 nm and narrow size distribution were closely spaced along the length of the high aspect ratio templates. The synthesized material was identified as a mixture of cubic Cu₂O and monoclinic CuO. UV/Vis absorption measurements were completed and a direct optical band gap ofmore » 2.87 eV was determined using Tauc's method. This value was slightly larger than bulk, signaling quantum confinement effects within the templated materials.« less

The local environment of Cu+ in Cu-Y zeolite and its relationship to the synthesis of dimethyl carbonate.

PubMed

Drake, Ian J; Zhang, Yihua; Briggs, Daniel; Lim, Bomyi; Chau, Tanguy; Bell, Alexis T

2006-06-22

Cu-exchanged Y zeolite was investigated in order to determine the location of the copper cations relative to the zeolite framework and to determine which Cu cations are active for the oxidative carbonylation of methanol to dimethyl carbonate (DMC). Cu-Y zeolite was prepared by vapor-phase exchange of H-Y with CuCl. The oxidation state, local coordination, and bond distances of Al and Cu were determined using Al K-edge and Cu K-edge X-ray absorption spectroscopy (XAS). Complimentary information was obtained by H2 temperature-programmed reduction and by in-situ infrared spectroscopy. Cu-Y has a Cu/Al ratio of unity and very little occluded CuCl. The average Al-O and Al-Cu bond distances are 1.67 angstroms and 2.79 angstroms, respectively, and the average Cu-O and Cu-Si(Al) bond distances are 1.99 angstroms and 3.13 angstroms, respectively. All of the Cu exchanged is present as Cu+ in sites I', II, and III'. Cu-Y is active for the oxidative carbonylation of methanol, and at low reactant contact time produces DMC as the primary product. With increasing reactant contact time, DMC formation decreases in preference to the formation of dimethoxy methane (DMM) and methylformate (MF). The formation of DMM and MF is attributed to the hydrogenation of DMC and the hydrogenolysis of DMM, respectively. Observation of the catalyst under reaction conditions reveals that most of the copper cations remain as Cu+, but some oxidation of Cu+ to Cu2+ does occur. It is also concluded that only those copper cations present in site II and III' positions are accessible to the reactants, and hence are catalytically active. The dominant adsorbed species on the surface are methoxy groups, and adsorbed CO is present as a minority species. The relationship of these observations to the kinetics of DMC synthesis is discussed.

Effect of annealing process on the heterostructure CuO/Cu2O as a highly efficient photocathode for photoelectrochemical water reduction

NASA Astrophysics Data System (ADS)

Du, Fan; Chen, Qing-Yun; Wang, Yun-Hai

2017-05-01

CuO/Cu2O photocathodes were successfully prepared via simply annealing the electrodeposited Cu2O on fluoride doped tin oxide (FTO) substrate. They were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscope (TEM), UV-vis absorption spectra and X-ray photoelectron spectroscopy (XPS). The results showed that the heterojunction of CuO/Cu2O was formed during the annealing process and presented the nature of p-type semiconductor. The photocurrent density and photoelectrochemical (PEC) stability of the p-type heterostructure CuO/Cu2O photocathode was improved greatly compared with the pure Cu2O, which was greatly affected by annealing time and temperature. The highest photo current density of -0.451 mA/cm2 and highest stability was obtained via annealing at 650 °C for 15 min (at -0.3 V vs. Ag/AgCl), which gave a remarkable improvement than the as-deposited Cu2O (-0.08 mA/cm2). This suggested that the CuO/Cu2O heterojunction facilitated the electron-hole pair separation and improved the photocathode's current and stability.

Synthesis of high-oxidation Y-Ba-Cu-O phases in superoxygenated thin films

NASA Astrophysics Data System (ADS)

Zhang, H.; Gauquelin, N.; McMahon, C.; Hawthorn, D. G.; Botton, G. A.; Wei, J. Y. T.

2018-03-01

It is known that solid-state reaction in high-pressure oxygen can stabilize high-oxidation phases of Y-Ba-Cu-O superconductors in powder form. We extend this superoxygenation concept of synthesis to thin films which, due to their large surface-to-volume ratio, are more reactive thermodynamically. Epitaxial thin films of YBa2Cu3O7 -δ grown by pulsed laser deposition are annealed at up to 700 atm O2 and 900 ∘C , in conjunction with Cu enrichment by solid-state diffusion. The films show the clear formation of Y2Ba4Cu7O15 -δ and Y2Ba4Cu8O16 as well as regions of YBa2Cu5O9 -δ and YBa2Cu6O10 -δ phases, according to scanning transmission electron microscopy, x-ray diffraction, and x-ray absorption spectroscopy. Similarly annealed YBa2Cu3O7 -δ powders show no phase conversion. Our results demonstrate a route of synthesis towards discovering more complex phases of cuprates and other superconducting oxides.

Lithographically fabricated silicon microreactor for operando QEXAFS studies in exhaust gas catalysis during simulation of a standard driving cycle

NASA Astrophysics Data System (ADS)

Doronkin, D. E.; Baier, S.; Sheppard, T.; Benzi, F.; Grunwaldt, J.-D.

2016-05-01

Selective catalytic reduction of NOx by ammonia over Cu-ZSM-5 was monitored by operando QEXAFS during simulation of the New European Driving Cycle. The required fast temperature transients were realized using a novel silicon microreactor, enabling simultaneous spectroscopic and kinetic analysis by X-ray absorption spectroscopy (XAS) and mass spectrometry (MS). Periods of high temperature were correlated to an increase in both N2 production and change of coordination of Cu sites. This operando approach using Si microreactors can be applied to other heterogeneous catalytic systems involving fast temperature transients.

Microwave Magnetochiral Dichroism in the Chiral-Lattice Magnet Cu2OSeO3

NASA Astrophysics Data System (ADS)

Okamura, Y.; Kagawa, F.; Seki, S.; Kubota, M.; Kawasaki, M.; Tokura, Y.

2015-05-01

Through broadband microwave spectroscopy in Faraday geometry, we observe distinct absorption spectra accompanying magnetoelectric (ME) resonance for oppositely propagating microwaves, i.e., directional dichroism, in the multiferroic chiral-lattice magnet Cu2OSeO3. The magnitude of the directional dichroism critically depends on the magnetic-field direction. Such behavior is well accounted for by considering the relative direction of the oscillating electric polarizations induced via the ME effect with respect to microwave electric fields. Directional dichroism in a system with an arbitrary form of ME coupling can be also discussed in the same manner.

Structural, optical and morphological characterization of Cu-doped α-Fe2O3 nanoparticles synthesized through co-precipitation technique

NASA Astrophysics Data System (ADS)

Lassoued, Abdelmajid; Lassoued, Mohamed Saber; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

2017-11-01

Pure and copper (Cu concentration varying from 2 to 8%) doped hematite (α-Fe2O3) nanocrystals were synthesized through co-precipitation method using simple equipment. X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, Differential Thermal Analysis (DTA), Thermo Gravimetric Analysis (TGA) and Ultraviolet-Visible (UV-Vis) techniques were used to characterize the synthesized samples. XRD measurements confirm that all the prepared nanocrystals consist only in nanocrystalline hematite phase. These results along with TEM and SEM show that the size of the nanoparticles decreases with Cu-doping down to 21 nm. FT-IR confirm the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we synthesized pure and Cu-doped hematite but also to identify their phonon modes. The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. The UV-Vis absorption measurements confirm that the decrease of particle size is accompanied by a decrease in the band gap value from 2.12 eV for pure α-Fe2O3 down to 1.91 eV for 8% Cu-doped α-Fe2O3. 8% Cu-doped hematite had the smallest size, the best crystallinity and the lowest band gap.

Low temperature synthesis of seed mediated CuO bundle of nanowires, their structural characterisation and cholesterol detection.

PubMed

Ibupoto, Z H; Khun, K; Liu, X; Willander, M

2013-10-01

In this study, we have successfully synthesised CuO bundle of nanowires using simple, cheap and low temperature hydrothermal growth method. The growth parameters such as precursor concentration and time for duration of growth were optimised. The field emission scanning electron microscopy (FESEM) has demonstrated that the CuO bundles of nanowires are highly dense, uniform and perpendicularly oriented to the substrate. The high resolution transmission electron microscopy (HRTEM) has demonstrated that the CuO nanostructures consist of bundle of nanowires and their growth pattern is along the [010] direction. The X-ray diffraction (XRD) technique described that CuO bundle of nanowires possess the monoclinic crystal phase. The surface and chemical composition analyses were carried out with X-ray photoelectron spectroscopy (XPS) technique and the obtained results suggested the pure crystal state of CuO nanostructures. In addition, the CuO nanowires were used for the cholesterol sensing application by immobilising the cholesterol oxidase through electrostatic attraction. The infrared reflection absorption spectroscopy study has also revealed that CuO nanostructures are consisting of only CuO bonding and has also shown the possible interaction of cholesterol oxidase with the sharp edge surface of CuO bundle of nanowires. The proposed cholesterol sensor has demonstrated the wide range of detection of cholesterol with good sensitivity of 33.88±0.96 mV/decade. Moreover, the CuO bundle of nanowires based sensor electrode has revealed good repeatability, reproducibility, stability, selectivity and a fast response time of less than 10s. The cholesterol sensor based on the immobilised cholesterol oxidase has good potential applicability for the determination of cholesterol from the human serum and other biological samples. Copyright © 2013 Elsevier B.V. All rights reserved.

X-ray absorption near-edge spectroscopy in bioinorganic chemistry: Application to M–O2 systems

PubMed Central

Sarangi, Ritimukta

2012-01-01

Metal K-edge X-ray absorption spectroscopy (XAS) has been extensively applied to bioinorganic chemistry to obtain geometric structure information on metalloprotein and biomimetic model complex active sites by analyzing the higher energy extended X-ray absorption fine structure (EXAFS) region of the spectrum. In recent years, focus has been on developing methodologies to interpret the lower energy K-pre-edge and rising-edge regions (XANES) and using it for electronic structure determination in complex bioinorganic systems. In this review, the evolution and progress of 3d-transition metal K-pre-edge and rising-edge methodology development is presented with particular focus on applications to bioinorganic systems. Applications to biomimetic transition metal–O2 intermediates (M = Fe, Co, Ni and Cu) are reviewed, which demonstrate the power of the method as an electronic structure determination technique and its impact in understanding the role of supporting ligands in tuning the electronic configuration of transition metal–O2 systems. PMID:23525635

In Situ Industrial Bimetallic Catalyst Characterization using Scanning Transmission Electron Microscopy and X-ray Absorption Spectroscopy at One Atmosphere and Elevated Temperature.

PubMed

Prestat, Eric; Kulzick, Matthew A; Dietrich, Paul J; Smith, Mr Matthew; Tien, Mr Eu-Pin; Burke, M Grace; Haigh, Sarah J; Zaluzec, Nestor J

2017-08-18

We have developed a new experimental platform for in situ scanning transmission electron microscope (STEM) energy dispersive X-ray spectroscopy (EDS) which allows real time, nanoscale, elemental and structural changes to be studied at elevated temperature (up to 1000 °C) and pressure (up to 1 atm). Here we demonstrate the first application of this approach to understand complex structural changes occurring during reduction of a bimetallic catalyst, PdCu supported on TiO 2 , synthesized by wet impregnation. We reveal a heterogeneous evolution of nanoparticle size, distribution, and composition with large differences in reduction behavior for the two metals. We show that the data obtained is complementary to in situ STEM electron energy loss spectroscopy (EELS) and when combined with in situ X-ray absorption spectroscopy (XAS) allows correlation of bulk chemical state with nanoscale changes in elemental distribution during reduction, facilitating new understanding of the catalytic behavior for this important class of materials. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Spectroscopic Definition of the CuZ° Intermediate in Turnover of Nitrous Oxide Reductase and Molecular Insight into the Catalytic Mechanism.

PubMed

Johnston, Esther M; Carreira, Cíntia; Dell'Acqua, Simone; Dey, Somdatta Ghosh; Pauleta, Sofia R; Moura, Isabel; Solomon, Edward I

2017-03-29

Spectroscopic methods and density functional theory (DFT) calculations are used to determine the geometric and electronic structure of Cu Z °, an intermediate form of the Cu 4 S active site of nitrous oxide reductase (N 2 OR) that is observed in single turnover of fully reduced N 2 OR with N 2 O. Electron paramagnetic resonance (EPR), absorption, and magnetic circular dichroism (MCD) spectroscopies show that Cu Z ° is a 1-hole (i.e., 3Cu I Cu II ) state with spin density delocalized evenly over Cu I and Cu IV . Resonance Raman spectroscopy shows two Cu-S vibrations at 425 and 413 cm -1 , the latter with a -3 cm -1 O 18 solvent isotope shift. DFT calculations correlated to these spectral features show that Cu Z ° has a terminal hydroxide ligand coordinated to Cu IV , stabilized by a hydrogen bond to a nearby lysine residue. Cu Z ° can be reduced via electron transfer from Cu A using a physiologically relevant reductant. We obtain a lower limit on the rate of this intramolecular electron transfer (IET) that is >10 4 faster than the unobserved IET in the resting state, showing that Cu Z ° is the catalytically relevant oxidized form of N 2 OR. Terminal hydroxide coordination to Cu IV in the Cu Z ° intermediate yields insight into the nature of N 2 O binding and reduction, specifying a molecular mechanism in which N 2 O coordinates in a μ-1,3 fashion to the fully reduced state, with hydrogen bonding from Lys397, and two electrons are transferred from the fully reduced μ 4 S 2- bridged tetranuclear copper cluster to N 2 O via a single Cu atom to accomplish N-O bond cleavage.

Electrochemical deposition of copper decorated titania nanotubes and its visible light photocatalytic performance

NASA Astrophysics Data System (ADS)

Lim, Y. C.; Siti, A. S.; Nur Amiera, P.; Devagi, K.; Lim, Y. P.

2017-09-01

Coupling of titania with narrow band gap materials has been a promising strategy in preparing visible light responsive photocatalyst. In this work, self-organized copper decorated TiO2 nanotube (Cu/TNT) was prepared via electrodeposition of Cu onto highly ordered titania nanotube arrays (TNT). The catalysts were characterized by X-ray diffraction, diffuse reflectance spectroscopy (DRS), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX). The DRS studies clearly show the extended absorption of Cu/TNT into the visible region and present a red shift of band gap to 2.1 eV. FESEM analysis has shown the dispersion of cubic-like Cu particles upon electrodeposition and EDX analysis supports the presence of copper species on the nanotubes surface. The photocatalytic ability of Cu/TNT was evaluated by the degradation of methyl orange from aqueous solution under low power visible light illumination. Compared to TNT, an appreciable improvement in methyl orange removal was observed for Cu/TNT and the highest removal efficiency of 80% was achieved. The effects of catalyst loading and samples repeatability were investigated and under optimum conditions, the removal efficiency of methyl orange over Cu/TNT had further increased to 93.4%. This work has demonstrated a feasible and simple way to introduce narrow band gap transition metal into nanotube arrays, which could create novel properties for functionalized nanotube arrays as well as promise a wide range of applications.

Room-temperature wide-range luminescence and structural, optical, and electrical properties of SILAR deposited Cu-Zn-S nano-structured thin films

NASA Astrophysics Data System (ADS)

Jose, Edwin; Kumar, M. C. Santhosh

2016-09-01

We report the deposition of nanostructured Cu-Zn-S composite thin films by Successive Ionic Layer Adsorption and Reaction (SILAR) method on glass substrates at room temperature. The structural, morphological, optical, photoluminescence and electrical properties of Cu-Zn-S thin films are investigated. The results of X-ray diffraction (XRD) and Raman spectroscopy studies indicate that the films exhibit a ternary Cu-Zn-S structure rather than the Cu xS and ZnS binary composite. Scanning electron microscope (SEM) studies show that the Cu-Zn-S films are covered well over glass substrates. The optical band gap energies of the Cu-Zn-S films are calculated using UV-visible absorption measurements, which are found in the range of 2.2 to 2.32 eV. The room temperature photoluminescence studies show a wide range of emissions from 410 nm to 565 nm. These emissions are mainly due to defects and vacancies in the composite system. The electrical studies using Hall effect measurements show that the Cu-Zn-S films are having p-type conductivity.

Improved performance of CdSe/CdS co-sensitized solar cells adopting efficient CuS counter electrode modified by PbS film using SILAR method

NASA Astrophysics Data System (ADS)

Zhang, Xiaolong; Lin, Yu; Wu, Jihuai; Fang, Biaopeng; Zeng, Jiali

2018-04-01

In this paper, CuS film was deposited onto fluorine-doped tin oxide (FTO) substrate using a facile chemical bath deposition method, and then modified by PbS using simple successive ionic layer absorption and reaction (SILAR) method with different cycles. These CuS/PbS films were utilized as counter electrodes (CEs) for CdSe/CdS co-sensitized solar cells. Field-emission scanning electron microscopy equipped with an energy-dispersive X-ray spectrometer was used to characterize the CuS/PbS films. The results show that CuS/PbS (10 cycles) CE exhibits an improved power conversion efficiency of 5.54% under the illumination of one sun (100 mW cm-2), which is higher than the CuS/PbS (0 cycles), CuS/PbS (5 cycles), and CuS/PbS (15 cycles) CEs. This enhancement is mainly attributed to good catalytic activity and lower charge-transfer and series resistances, which have been proved by electrochemical impedance spectroscopy, and Tafel polarization measurements.

Optical and electrical stability of viral-templated copper sulfide (Cu{sub 1.8}S) films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shahriar Zaman, Mohammed; Bernard Grajeda, Gabriel; Haberer, Elaine D., E-mail: haberer@ucr.edu

The optical and electrical stabilities of viral-templated non-stoichiometric copper sulfide, digenite (Cu{sub 1.8}S) films were investigated. The films were composed of large agglomerates of randomly aligned Cu{sub 1.8}S-coated M13 filamentous phage. Free carrier optical absorption associated with localized surface plasmon resonance (LSPR) was observed in the near infrared spectral region, and the films were electrically active, displaying a linear current-voltage relationship. Under ambient conditions, the magnitude of the LSPR absorption increased, following a power law relationship with time, and the electrical resistance of viral-templated films decreased significantly. In contrast, the resistance of films stored under low oxygen, low humidity conditionsmore » experienced a smaller reduction in electrical resistance. Changes in optical and electrical film properties under ambient conditions were associated with an increase in free carrier concentration within the copper chalcogenide material due to oxygen exposure. X-ray photoelectron spectroscopy was used to relate this increase in free carrier concentration to compositional changes on the viral-templated material surface.« less

On the Electronic Structure of Cu Chlorophyllin and Its Breakdown Products: A Carbon K-Edge X-ray Absorption Spectroscopy Study.

PubMed

Witte, Katharina; Mantouvalou, Ioanna; Sánchez-de-Armas, Rocío; Lokstein, Heiko; Lebendig-Kuhla, Janina; Jonas, Adrian; Roth, Friedrich; Kanngießer, Birgit; Stiel, Holger

2018-02-15

Using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, the carbon backbone of sodium copper chlorophyllin (SCC), a widely used chlorophyll derivative, and its breakdown products are analyzed to elucidate their electronic structure and physicochemical properties. Using various sample preparation methods and complementary spectroscopic methods (including UV/Vis, X-ray photoelectron spectroscopy), a comprehensive insight into the SCC breakdown process is presented. The experimental results are supported by density functional theory calculations, allowing a detailed assignment of characteristic NEXAFS features to specific C bonds. SCC can be seen as a model system for the large group of porphyrins; thus, this work provides a novel and detailed description of the electronic structure of the carbon backbone of those molecules and their breakdown products. The achieved results also promise prospective optical pump/X-ray probe investigations of dynamic processes in chlorophyll-containing photosynthetic complexes to be analyzed more precisely.

Synthesis and characterization of metal-dielectric composites with copper nanoparticles embedded in a glass matrix: A multitechnique approach

NASA Astrophysics Data System (ADS)

Lipinska-Kalita, Kristina E.; Krol, Denise M.; Hemley, Russell J.; Mariotto, Gino; Kalita, Patricia E.; Ohki, Yoshimichi

2005-09-01

The precipitation and growth of copper nanoparticles in an optically transparent aluminosilicate glass matrix was investigated. The size of particles in this heterophase glass-based composite was modified in a controlled manner by isothermal heat treatments. A multitechnique approach, consisting of Raman scattering spectroscopy, high-resolution transmission electron microscopy, x-ray diffraction technique, and optical absorption spectroscopy, has been used to study the nucleation and crystallization processes. Optical absorption spectroscopy revealed the presence of intense absorption bands attributed to oscillations of free electrons, known as the surface-plasmon resonance band of copper particles, and confirmed a gradual increase of the particles' mean size and density with annealing time. The Raman scattering on acoustical phonons from Cu quantum dots in the glass matrix measured for off-resonance conditions demonstrated the presence of intense, inhomogeneously broadened peaks that have been assigned to the confined acoustic eigenmodes of copper nanoparticles. The particle-size dependence of the acoustic peak energies and the relation between the size distribution and bandwidths of these peaks were derived. High-resolution transmission electron microscopy was used to monitor the nucleation of the nanoparticles and to estimate their mean size.

Selective liquid phase oxidation of benzyl alcohol to benzaldehyde by tert-butyl hydroperoxide over γ-Al2O3 supported copper and gold nanoparticles

NASA Astrophysics Data System (ADS)

Ndolomingo, Matumuene Joe; Meijboom, Reinout

2017-03-01

Benzyl alcohol oxidation to benzaldehyde was performed by tert-butyl hydroperoxide (TBHP) in the absence of any solvent using γ-Al2O3 supported copper and gold nanoparticles. Li2O and ionic liquids were used as additive and stabilizers for the synthesis of the catalysts. The physico-chemical properties of the catalysts were characterized by atomic absorption spectroscopy (AAS), X-ray diffraction spectroscopy (XRD), N2 absorption/desorption (BET), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and temperature programmed reduction (TPR), whereas, the oxidation reaction was followed by gas chromatography with a flame ionization detector (GC-FID). The as prepared catalysts exhibited good catalytic performance in terms of conversion and selectivity towards benzaldehyde. The performance of the Au-based catalysts is significantly higher than that of the Cu-based catalysts. For both Cu and Au catalysts, the conversion of benzyl alcohol increased as the reaction proceeds, while the selectivity for benzaldehyde decreased. Moreover, the catalysts can be easily recycled and reused with neither significant loss of activity nor selectivity. A kinetic study for the Cu and Au-catalyzed oxidation of benzyl alcohol to benzyldehyde is reported. The rate at which the oxidation of benzyl alcohol is occurring as a function of catalyst and oxidant amounts was investigated, with the apparent rate constant, kapp being proportional to the amount of nano catalyst and oxygen present in the system.

Structural characterization and optical constants of CuIn3Se5 vacuum and air annealed thin films

NASA Astrophysics Data System (ADS)

Segmane, N. E. H.; Abdelkader, D.; Amara, A.; Drici, A.; Akkari, F. Chaffar; Khemiri, N.; Bououdina, M.; Kanzari, M.; Bernède, J. C.

2018-01-01

Milled powder of ordered defect compound (ODC) CuIn3Se5 phase was successfully synthesized via milling process. Thin films of CuIn3Se5 were deposited onto glass substrates at room temperature by thermal evaporation technique. The obtained layers were annealed in vacuum and air atmosphere. The structural and compositional properties of the powder were analyzed using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Powder XRD characterization, Rietveld analysis and chemical bounding confirm the tetragonal ordered defect compound phase formation with lattice constants a = 5.732 Å and c = 11.575 Å. Thin films were characterized by XRD, atomic force microscopy (AFM) and UV/Vis spectroscopy. Transmittance (T) and reflectance (R) spectra were measured in the spectral range of 300-1800 nm. The absorption coefficient α exhibits high values in the visible range and reaches a value of 105 cm-1. The band gap energy Eg of the annealed thin films is estimated to be approximately 1.75 eV. The refractive index n was estimated from transmittance data using Swanepoel's method. The refractive indices of the films as a function of wavelengths can be fitted with Cauchy dispersion equation. The oscillator energy E0, dispersion energy Ed, zero frequency refractive index n0, high frequency dielectric constant ε∞ and the carrier concentration per effective mass N/m∗ values were determined from the analysis of the experimental data using Wemple-DiDomenico and Spitzer-Fan models. We exploited the refractive index dispersion for the determination of the magneto-optical constant V, which characterizes the Faraday rotation. The nonlinear optical parameters namely nonlinear susceptibility χ(3), nonlinear refractive index and nonlinear absorption coefficient β are investigated for the first time for CuIn3Se5 material.

Development of sputtered CuSbS2 thin films grown by sequential deposition of binary sulfides

NASA Astrophysics Data System (ADS)

Medina-Montes, M. I.; Vieyra-Brito, O.; Mathews, N. R.; Mathew, X.

2018-05-01

In this work, CuSbS2 thin films were developed by annealing binary precursors deposited sequentially by rf magnetron sputtering. The recrystallization process was optimized and the films were extensively characterized using a number of tools such as XRD, Raman, SEM, energy dispersive x-ray spectroscopy, atomic force microscopy, Hall, UV–vis spectroscopy, Ellipsometry, Seebeck, and photoresponse. The influence of annealing temperature on the structure, morphology, elemental composition, optical and electrical properties are reported. Annealing below 350 °C resulted in famatinite (Cu3SbS4) and chalcostibite (CuSbS2) ternaries as well as binary phases. Phase-pure chalcostibite was obtained in the range of 350 °C–375 °C. At 400 °C, although CuSbS2 was predominant, tetrahedrite phase (Cu12Sb4S13) appeared as an additional phase. The elemental composition of the films was slightly sulfur deficient, and the atomic percentages of Cu, Sb and S showed a dependence on annealing temperature. The material properties of the phase-pure CuSbS2 thin films are: optical band gap in the range of 1.5–1.62 eV, absorption coefficient close to 105 cm‑1, atomic ratios of Cu/Sb ∼1 and (Cu + Sb)/S ∼1.2, crystal size 18.3–24.5 nm and grain size 50–300 nm. The films were photo-sensitive, showed p-type semiconductor behavior. Electrical resistivity, carrier density and hole mobility were 94–459 Ω cm, 1.6–7.0 × 1015 cm‑3 and 8.4–9.5 cm2 V‑1 s respectively.

Spectroscopic, Computational and Kinetic Studies of the μ4-Sulfide Bridged Tetranuclear CuZ Cluster in N2O Reductase: pH Effect on the Edge Ligand and its Contribution to Reactivity

PubMed Central

Ghosh, Somdatta; Gorelsky, Serge I.; George, Serena DeBeer; Chan, Jeannine M.; Cabrito, Inês; Dooley, David M.; Moura, José J. G.; Moura, Isabel; Solomon, Edward I.

2008-01-01

A combination of spectroscopy and DFT calculations has been used to evaluate the pH effect at the CuZ site in Pseudomonas nautica (Pn) N2OR and Achromobacter cycloclastes (Ac) N2OR and its relevance to catalysis. Absorption, MCD, EPR with sulfur K-edge XAS spectra of the enzymes at high and low pH show minor changes. However, resonance Raman (rR) spectroscopy of PnN2OR at high pH shows that the 415 cm−1 Cu-S vibration (observed at low pH) shifts to higher frequency, loses intensity and obtains a 9 cm−1 18O shift, implying significant Cu-O character, demonstrating the presence of a OH− ligand at the CuICuIV edge. From DFT calculations both protonation of the OH− to H2O or the μ4-S2− to μ4-SH− would produce large spectral changes which are not observed. Alternatively, DFT calculations including a lysine residue at an H-bonding distance from the CuICuIV edge ligand show that the position of the OH− ligand depends on the protonation state of the lysine. This would change the coupling of the Cu-(OH) stretch with the Cu-S stretch, as observed in the rR spectrum. Thus the observed pH effect (pKa ~9.2) likely reflects protonation equilibrium of the lysine residue which would both raise E0 and provide a proton for lowering the barrier for the N-O cleavage and for reduction of the [Cu4S(im)7OH]2+ to the fully reduced 4CuI active form for turnover. PMID:17352474

Microwave heating synthesis and formation mechanism of chalcopyrite structured CuInS{sub 2} nanorods in deep eutectic solvent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jianjun, E-mail: zhangjianjun7110@163.com; Chen, Jun; Li, Qiang

2015-03-15

Graphical abstract: Chalcopyrite structured CuInS{sub 2} nanorods were synthesized by an environmentally friendly microwave heating method in deep eutectic solvent. Results show that microwave heating time plays an important role in the formation of CuInS{sub 2} nanostructure phase. The SEM results indicated that the obtained CuInS{sub 2} nanostructures display rod-like morphology with diameters of about 40 nm and lengths of about 400 nm. The UV–vis spectrum results indicated that the CuInS{sub 2} nanorods exhibit strong absorption from the entire visible light region to the near-infrared region beyond 1100 nm. The possible growth mechanism of CuInS{sub 2} nanorods was discussed. -more » Abstract: Chalcopyrite structured CuInS{sub 2} nanorods were synthesized by an environmentally friendly microwave heating method in deep eutectic solvent. The as-synthesized CuInS{sub 2} nanorods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The results indicated that the obtained CuInS{sub 2} nanostructures display rod-like morphology with diameters of about 40 nm and lengths of about 400 nm. The influences of microwave heating time on the formation of CuInS{sub 2} phase were discussed. Ultraviolet–visible (UV–vis) and photoluminescence (PL) spectra were utilized to investigate the optical properties of CuInS{sub 2} nanorods. The results showed that the as-synthesized CuInS{sub 2} nanorods exhibit strong absorption from the entire visible light region to the near-infrared region beyond 1100 nm. PL spectrum of the as-synthesized CuInS{sub 2} nanorods displays an emission peak centered at 580 nm under excitation wavelength of 366 nm at room temperature. The possible growth mechanism of CuInS{sub 2} nanorods was discussed.« less

Functionalization of nanocrystalline diamond films with phthalocyanines

NASA Astrophysics Data System (ADS)

Petkov, Christo; Reintanz, Philipp M.; Kulisch, Wilhelm; Degenhardt, Anna Katharina; Weidner, Tobias; Baio, Joe E.; Merz, Rolf; Kopnarski, Michael; Siemeling, Ulrich; Reithmaier, Johann Peter; Popov, Cyril

2016-08-01

Phthalocyanine (Pc) derivatives containing different central metal atoms (Mn, Cu, Ti) and different peripheral chains were synthesized and comprehensively characterized. Their interaction with nanocrystalline diamond (NCD) films, as-grown by hot-filament chemical vapor deposition or after their modification with oxygen plasma to exchange the hydrogen termination with oxygen-containing groups, was studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The elemental composition as determined by XPS showed that the Pc were grafted on both as-grown and O-terminated NCD. Mn, Cu and Ti were detected together with N stemming from the Pc ring and S in case of the Ti-Pc from the peripheral ligands. The results for the elemental surface composition and the detailed study of the N 1s, S 2p and O 1s core spectra revealed that Ti-Pc grafted better on as-grown NCD but Cu-Pc and Mn-Pc on O-terminated films. Samples of Mn-Pc on as-grown and O-terminated NCD were further investigated by NEXAFS spectroscopy. The results showed ordering of the grafted molecules, laying flat on the H-terminated NCD surface while only the macrocycles were oriented parallel to the O-terminated surface with the peripheral chains perpendicular to it.

Selective anaerobic oxidation of methane enables direct synthesis of methanol.

PubMed

Sushkevich, Vitaly L; Palagin, Dennis; Ranocchiari, Marco; van Bokhoven, Jeroen A

2017-05-05

Direct functionalization of methane in natural gas remains a key challenge. We present a direct stepwise method for converting methane into methanol with high selectivity (~97%) over a copper-containing zeolite, based on partial oxidation with water. The activation in helium at 673 kelvin (K), followed by consecutive catalyst exposures to 7 bars of methane and then water at 473 K, consistently produced 0.204 mole of CH 3 OH per mole of copper in zeolite. Isotopic labeling confirmed water as the source of oxygen to regenerate the zeolite active centers and renders methanol desorption energetically favorable. On the basis of in situ x-ray absorption spectroscopy, infrared spectroscopy, and density functional theory calculations, we propose a mechanism involving methane oxidation at Cu II oxide active centers, followed by Cu I reoxidation by water with concurrent formation of hydrogen. Copyright © 2017, American Association for the Advancement of Science.

Enhanced photocatalytic activity of ZnO/CuO nanocomposite for the degradation of textile dye on visible light illumination.

PubMed

Saravanan, R; Karthikeyan, S; Gupta, V K; Sekaran, G; Narayanan, V; Stephen, A

2013-01-01

The photocatalytic degradation of organic dyes such as methylene blue and methyl orange in the presence of various percentages of composite catalyst under visible light irradiation was carried out. The catalyst ZnO nanorods and ZnO/CuO nanocomposites of different weight ratios were prepared by new thermal decomposition method, which is simple and cost effective. The prepared catalysts were characterized by different techniques such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV-visible absorption spectroscopy. Further, the most photocatalytically active composite material was used for degradation of real textile waste water under visible light illumination. The irradiated samples were analysed by total organic carbon and chemical oxygen demand. The efficiency of the catalyst and their photocatalytic mechanism has been discussed in detail. Copyright © 2012 Elsevier B.V. All rights reserved.

Spectroscopic studies on Solvatochromism of mixed-chelate copper(II) complexes using MLR technique

NASA Astrophysics Data System (ADS)

Golchoubian, Hamid; Moayyedi, Golasa; Fazilati, Hakimeh

2012-01-01

Mixed-chelate copper(II) complexes with a general formula [Cu(acac)(diamine)]X where acac = acetylacetonate ion, diamine = N,N-dimethyl,N'-benzyl-1,2-diaminoethane and X = BPh 4-, PF 6-, ClO 4- and BF 4- have been prepared. The complexes were characterized on the basis of elemental analysis, molar conductance, UV-vis and IR spectroscopies. The complexes are solvatochromic and their solvatochromism were investigated by visible spectroscopy. All complexes demonstrated the positive solvatochromism and among the complexes [Cu(acac)(diamine)]BPh 4·H 2O showed the highest Δ νmax value. To explore the mechanism of interaction between solvent molecules and the complexes, different solvent parameters such as DN, AN, α and β using multiple linear regression (MLR) method were employed. The statistical results suggested that the DN parameter of the solvent plays a dominate contribution to the shift of the d-d absorption band of the complexes.

Incorporation of copper nanoparticles into paper for point-of-use water purification

PubMed Central

Smith, James A.

2014-01-01

As a cost-effective alternative to silver nanoparticles, we have investigated the use of copper nanoparticles in paper filters for point-of-use water purification. This work reports an environmentally benign method for the direct in situ preparation of copper nanoparticles (CuNPs) in paper by reducing sorbed copper ions with ascorbic acid. Copper nanoparticles were quickly formed in less than 10 minutes and were well distributed on the paper fiber surfaces. Paper sheets were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, and atomic absorption spectroscopy. Antibacterial activity of the CuNP sheets was assessed for by passing Escherichia coli bacteria suspensions through the papers. The effluent was analyzed for viable bacteria and copper release. The CuNP papers with higher copper content showed a high bacteria reduction of log 8.8 for E. coli. The paper sheets containing copper nanoparticles were effective in inactivating the test bacteria as they passed through the paper. The copper levels released in the effluent water were below the recommended limit for copper in drinking water (1 ppm). PMID:25014431

The valence of Ru, Ce and Eu ions in the magneto-superconductor Eu 1.5Ce 0.5RuSr 2Cu 2O 10

NASA Astrophysics Data System (ADS)

Felner, I.; Asaf, U.; Godart, C.; Alleno, E.

1999-01-01

The superconducting (T c∼32 K) Eu 1.5Ce 0.5RuSr 2Cu 2O 10 (Ru-2122) material is also magnetically ordered (T M∼122 K) with TM≫ Tc. Superconductivity (SC) is confined to the CuO 2 planes, whereas magnetism is due to the Ru sublattice. Mossbauer spectroscopy performed at 90 and 300 K on 151Eu shows a single narrow line with an isomer shift=0.69(2) and a quadrupole splitting of 1.84 mm/s, indicating that the Eu ions are trivalent with a nonmagnetic J=0 ground state. This is in agreement with X-ray-absorption spectroscopy (XAS) taken at L III edges of Eu, Ce which shows that Eu is trivalent and Ce is tetravalent. XAS experiments at the K edge of Ru indicate that Ru is pentavalent. This indicates, that in the M-2122 system, SC exists only for pentavalent M ions such as Ta, Nb and Ru.

Electronic structures of C u 2 O , C u 4 O 3 , and CuO: A joint experimental and theoretical study

DOE PAGES

Wang, Y.; Lany, S.; Ghanbaja, J.; ...

2016-12-14

We present a joint experimental and theoretical study for the electronic structures of copper oxides including Cu 2O, CuO, and the metastable mixed-valence oxide Cu 4O 3. The optical band gap is determined by experimental optical absorption coefficient, and the electronic structure in valence and conduction bands is probed by photoemission and electron energy loss spectroscopies, respectively. Furthermore, we compare our experimental results with many-body GW calculations utilizing an additional on-site potential for d-orbital energies that facilitates tractable and predictive computations. The side-by-side comparison between the three oxides, including a band insulator (Cu2O) and two Mott/charge-transfer insulators (CuO, Cu 4Omore » 3) leads to a consistent picture for the optical and band-structure properties of the Cu oxides, strongly supporting indirect band gaps of about 1.2 and 0.8 eV in CuO and Cu 4O 3, respectively. This comparison also points towards surface oxidation and reduction effects that can complicate the interpretation of the photoemission spectra.« less

Efficient photocatalytic degradation of rhodamine-B by Fe doped CuS diluted magnetic semiconductor nanoparticles under the simulated sunlight irradiation

NASA Astrophysics Data System (ADS)

Sreelekha, N.; Subramanyam, K.; Amaranatha Reddy, D.; Murali, G.; Rahul Varma, K.; Vijayalakshmi, R. P.

2016-12-01

The present work is planned for a simple, inexpensive and efficient approach for the synthesis of Cu1-xFexS (x = 0.00, 0.01, 0.03, 0.05 and 0.07) nanoparticles via simplistic chemical co-precipitation route by using ethylene diamine tetra acetic acid (EDTA) as a capping molecules. As synthesized nanoparticles were used as competent catalysts for degradation of rhodamine-B organic dye pollutant. The properties of prepared samples were analyzed with energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible optical absorption spectroscopy, Fourier transform infrared (FTIR) spectra, Raman spectra and vibrating sample magnetometer (VSM). EDAX spectra corroborated the existence of Fe in prepared nanoparticles within close proximity to stoichiometric ratio. XRD, FTIR and Raman patterns affirmed that configuration of single phase hexagonal crystal structure as that of (P63/mmc) CuS, without impurity crystals. The average particle size estimated by TEM scrutiny is in the assortment of 5-10 nm. UV-visible optical absorption measurements showed that band gap narrowing with increasing the Fe doping concentration. VSM measurements revealed that 3% Fe doped CuS nanoparticles exhibited strong ferromagnetism at room temperature and changeover of magnetic signs from ferromagnetic to the paramagnetic nature with increasing the Fe doping concentration in CuS host lattice. Among all Fe doped CuS nanoparticles, 3% Fe inclusion CuS sample shows better photocatalytic performance in decomposition of RhB compared with the pristine CuS. Thus as synthesized Cu0·97Fe0·03S nanocatalysts are tremendously realistic compounds for photocatalytic fictionalization in the direction of organic dye degradation under visible light.

Nano Catalysts for Diesel Engine Emission Remediation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narula, Chaitanya Kumar; Yang, Xiaofan; Debusk, Melanie Moses

2012-06-01

The objective of this project was to develop durable zeolite nanocatalysts with broader operating temperature windows to treat diesel engine emissions to enable diesel engine based equipment and vehicles to meet future regulatory requirements. A second objective was to improve hydrothermal durability of zeolite catalysts to at least 675 C. The results presented in this report show that we have successfully achieved both objectives. Since it is accepted that the first step in NO{sub x} conversion under SCR (selective catalytic reduction) conditions involves NO oxidation to NO{sub 2}, we reasoned that catalyst modification that can enhance NO oxidation at low-temperaturesmore » should facilitate NO{sub x} reduction at low temperatures. Considering that Cu-ZSM-5 is a more efficient catalyst than Fe-ZSM-5 at low-temperature, we chose to modify Cu-ZSM-5. It is important to point out that the poor low-temperature efficiency of Fe-ZSM-5 has been shown to be due to selective absorption of NH{sub 3} at low-temperatures rather than poor NO oxidation activity. In view of this, we also reasoned that an increased electron density on copper in Cu-ZSM-5 would inhibit any bonding with NH{sub 3} at low-temperatures. In addition to modified Cu-ZSM-5, we synthesized a series of new heterobimetallic zeolites, by incorporating a secondary metal cation M (Sc{sup 3+}, Fe{sup 3+}, In{sup 3+}, and La{sup 3+}) in Cu exchanged ZSM-5, zeolite-beta, and SSZ-13 zeolites under carefully controlled experimental conditions. Characterization by diffuse-reflectance ultra-violet-visible spectroscopy (UV-Vis), X-ray powder diffraction (XRD), extended X-ray absorption fine structure spectroscopy (EXAFS) and electron paramagnetic resonance spectroscopy (EPR) does not permit conclusive structural determination but supports the proposal that M{sup 3+} has been incorporated in the vicinity of Cu(II). The protocols for degreening catalysts, testing under various operating conditions, and accelerated aging conditions were provided by our collaborators at John Deere Power Systems. Among various zeolites reported here, CuFe-SSZ-13 offers the best NO{sub x} conversion activity in 150-650 C range and is hydrothermally stable when tested under accelerated aging conditions. It is important to note that Cu-SSZ-13 is now a commercial catalyst for NO{sub x} treatment on diesel passenger vehicles. Thus, our catalyst performs better than the commercial catalyst under fast SCR conditions. We initially focused on fast SCR tests to enable us to screen catalysts rapidly. Only the catalysts that exhibit high NO{sub x} conversion at low temperatures are selected for screening under varying NO{sub 2}:NO{sub x} ratio. The detailed tests of CuFe-SSZ-13 show that CuFe-SSZ-13 is more effective than commercial Cu-SSZ-13 even at NO{sub 2}:NO{sub x} ratio of 0.1. The mechanistic studies, employing stop-flow diffuse reflectance FTIR spectroscopy (DRIFTS), suggest that high concentration of NO{sup +}, generated by heterobimetallic zeolites, is probably responsible for their superior low temperature NO{sub x} activity. The results described in this report clearly show that we have successfully completed the first step in a new emission treatment catalyst which is synthesis and laboratory testing employing simulated exhaust. The next step in the catalyst development is engine testing. Efforts are in progress to obtain follow-on funding to carry out scale-up and engine testing to facilitate commercialization of this technology.« less

Effect of counterpart metals in carbon-supported Pt-based catalysts prepared using radiation chemical method

NASA Astrophysics Data System (ADS)

Okazaki, Tomohisa; Seino, Satoshi; Matsuura, Yoshiyuki; Otake, Hiroaki; Kugai, Junichiro; Ohkubo, Yuji; Nitani, Hiroaki; Nakagawa, Takashi; Yamamoto, Takao A.

2017-04-01

The process of nanoparticle formation by radiation chemical synthesis in a heterogeneous system has been investigated. Carbon-supported Pt-based bimetallic nanoparticles were synthesized using a high-energy electron beam. Rh, Cu, Ru, and Sn were used as counterpart metals. The nanoparticles were characterized by inductively coupled plasma atomic emission spectrometry, transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy. PtRh formed a uniform random alloy nanoparticle, while Cu partially formed an alloy with Pt and the remaining Cu existed as CuO. PtRu formed an alloy structure with a composition distribution of a Pt-rich core and Ru-rich shell. No alloying was observed in PtSn, which had a Pt-SnO2 structure. The alloy and oxide formation mechanisms are discussed considering the redox potentials, the standard enthalpy of oxide formation, and the solid solubilities of Pt and the counterpart metals.

Fate of bromine in pyrolysis of printed circuit board wastes.

PubMed

Chien, Y C; Wang, H P; Lin, K S; Huang, Y J; Yang, Y W

2000-02-01

Behavior of Br in pyrolysis of the printed circuit board waste with valuable copper and oil recycling has been studied in the present work. Experimentally, pyrolysis of the printed circuit board waste generated approximately 40.6% of oils, 24.9% of noncondensible gases and 34.5% of solid residues that enriched in copper (90-95%). The cuts of the oils produced from pyrolysis of the printed circuit board waste into weighted boiling fraction were primarily light naphtha and heavy gas oil. Approximately 72.3% of total Br in the printed circuit board waste were found in product gas mainly as HBr and bromobenzene. However, by extended X-ray absorption fine structural (EXAFS) spectroscopy, Cu-O and Cu-(O)-Cu species with bond distance of 1.87 and 2.95 A, respectively, were observed in the solid residues. Essentially, no Cu-Br species was found.

Matrix infrared spectroscopy and quantum-chemical calculations for the coinage-metal fluorides: comparisons of Ar-AuF, Ne-AuF, and Molecules MF2 and MF3.

PubMed

Wang, Xuefeng; Andrews, Lester; Brosi, Felix; Riedel, Sebastian

2013-01-21

The reactions of laser-ablated Au, Ag, and Cu atoms with F(2) in excess argon and neon gave new absorptions in the M-F stretching region of their IR spectra, which were assigned to metal-fluoride species. For gold, a Ng-AuF bond was identified in mixed neon/argon samples. However, this bonding was much weaker with AgF and CuF. Molecules MF(2) and MF(3) (M=Au, Ag, Cu) were identified from the isotopic distribution of the Cu and Ag atoms, comparison of the frequencies for three metal fluorides, and theoretical frequency calculations. The AuF(5) molecule was characterized by its strongest stretching mode and theoretical frequency calculations. Additional evidence was observed for the formation of the Au(2) F(6) molecule. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhang-Rice physics and anomalous copper states in A-site ordered perovskites

PubMed Central

Meyers, D.; Mukherjee, Swarnakamal; Cheng, J.-G.; Middey, S.; Zhou, J.-S.; Goodenough, J. B.; Gray, B. A.; Freeland, J. W.; Saha-Dasgupta, T.; Chakhalian, J.

2013-01-01

In low dimensional cuprates several interesting phenomena, including high Tc superconductivity, are deeply connected to electron correlations on Cu and the presence of the Zhang-Rice (ZR) singlet state. Here, we report on direct spectroscopic observation of the ZR state responsible for the low-energy physical properties in two isostructural A-site ordered cuprate perovskites, CaCu3Co4O12 and CaCu3Cr4O12 as revealed by resonant soft x-ray absorption spectroscopy on the Cu L3,2- and O K-edges. These measurements reveal the signature of Cu in the high-energy 3+ (3d8), the typical 2+ (3d9), as well as features of the ZR singlet state (i.e., 3d9L, L denotes an oxygen hole). First principles GGA + U calculations affirm that the B-site cation controls the degree of Cu-O hybridization and, thus, the Cu valency. These findings introduce another avenue for the study and manipulation of cuprates, bypassing the complexities inherent to conventional chemical doping (i.e. disorder) that hinder the relevant physics. PMID:23666066

Copper cluster size effect in methanol synthesis from CO 2

DOE PAGES

Yang, Bing; Liu, Cong; Halder, Avik; ...

2017-05-08

Here, size-selected Cu n catalysts ( n = 3, 4, 20) were synthesized on Al 2O 3 thin films using mass-selected cluster deposition. A systematic study of size and support effects was carried out for CO 2 hydrogenation at atmospheric pressure using a combination of in situ grazing incidence X-ray absorption spectroscopy, catalytic activity measurement, and first-principles calculations. The catalytic activity for methanol synthesis is found to strongly vary as a function of the cluster size; the Cu 4/Al 2O 3 catalyst shows the highest turnover rate for CH 3OH production. With only one atom less than Cu 4, Cumore » 3 showed less than 50% activity. Density functional theory calculations predict that the activities of the gas-phase Cu clusters increase as the cluster size decreases; however, the stronger charge transfer interaction with Al 2O 3 support for Cu 3 than for Cu 4 leads to remarkably reduced binding strength between the adsorbed intermediates and supported Cu 3, which subsequently results in a less favorable energetic pathway to transform carbon dioxide to methanol.« less

Low Absorption Vitreous Carbon Reactors for Operando XAS: A Case Study on Cu/Zeolites for Selective Catalytic Reduction of NOx by NH3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kispersky, Vincent F.; Kropf, A. Jeremy; Ribeiro, Fabio H.

2012-01-01

We describe the use of vitreous carbon as an improved reactor material for an operando X-ray absorption spectroscopy (XAS) plug-flow reactor. These tubes significantly broaden the operating range for operando experiments. Using selective catalytic reduction (SCR) of NO x by NH₃ on Cu/Zeolites (SSZ-13, SAPO-34 and ZSM-5) as an example reaction, we illustrate the high-quality XAS data achievable with these reactors. The operando experiments showed that in Standard SCR conditions of 300 ppm NO, 300 ppm NH₃, 5% O₂, 5% H₂O, 5% CO₂ and balance He at 200 °C, the Cu was a mixture of Cu(I) and Cu(II) oxidation states.more » XANES and EXAFS fitting found the percent of Cu(I) to be 15%, 45% and 65% for SSZ-13, SAPO-34 and ZSM-5, respectively. For Standard SCR, the catalytic rates per mole of Cu for Cu/SSZ-13 and Cu/SAPO-34 were about one third of the rate per mole of Cu on Cu/ZSM-5. Based on the apparent lack of correlation of rate with the presence of Cu(I), we propose that the reaction occurs via a redox cycle of Cu(I) and Cu(II). Cu(I) was not found in in situSCR experiments on Cu/Zeolites under the same conditions, demonstrating a possible pitfall of in situ measurements. A Cu/SiO₂ catalyst, reduced in H₂ at 300 °C, was also used to demonstrate the reactor's operando capabilities using a bending magnet beamline. Analysis of the EXAFS data showed the Cu/SiO₂ catalyst to be in a partially reduced Cu metal–Cu(I) state. In addition to improvements in data quality, the reactors are superior in temperature, stability, strength and ease of use compared to previously proposed borosilicate glass, polyimide tubing, beryllium and capillary reactors. The solid carbon tubes are non-porous, machinable, can be operated at high pressure (tested at 25 bar), are inert, have high material purity and high X-ray transmittance.« less

Synthesis and properties of nanocrystalline copper indium oxide thin films deposited by Rf magnetron sputtering.

PubMed

Singh, Mandeep; Singh, V N; Mehta, B R

2008-08-01

Nanocrystalline copper indium oxide (CuInO2) thin films with particle size ranging from 25 nm to 71 nm have been synthesized from a composite target using reactive Rf magnetron sputtering technique. X-ray photoelectron spectroscopy (XPS) combined with glancing angle X-ray diffraction (GAXRD) analysis confirmed the presence of delafossite CuInO2 phase in these films. The optical absorption studies show the presence of two direct band gaps at 3.3 and 4.3 eV, respectively. The resistance versus temperature measurements show thermally activated hopping with activation energy of 0.84 eV to be the conduction mechanism.

Skeletal Ru/Cu catalysts prepared from crystalline and quasicrystalline ternary alloy precursors: characterization by X-ray absorption spectroscopy and CO oxidation.

PubMed

Highfield, James; Liu, Tao; Loo, Yook Si; Grushko, Benjamin; Borgna, Armando

2009-02-28

The Ru/Cu system is of historical significance in catalysis. The early development and application of X-ray absorption spectroscopy (XAS) led to the original 'bimetallic cluster" concept for highly-immiscible systems. This work explores alkali leaching of Al-based ternary crystalline and quasicrystalline precursors as a potential route to bulk Ru/Cu alloys. Single-phase ternary alloys at 3 trial compositions; Al(71)Ru(22)Cu(7), Al(70.5)Ru(17)Cu(12.5), and Al(70)Ru(10)Cu(20), were prepared by arc melting of the pure metal components. After leaching, the bimetallic residues were characterized principally by transmission XAS, "as-leached" and after annealing in H(2) (and passivation) in a thermobalance. XRD and BET revealed a nanocrystalline product with a native structure of hexagonal Ru. XPS surface analysis of Ru(22)Cu(7) and Ru(17)Cu(12.5) found only slight enrichment by Cu in the as-leached forms, with little change upon annealing. Ru(10)Cu(20) was highly segregated as-leached. XANES data showed preferential oxidation of Cu in Ru(22)Cu(7), implying that it exists as an encapsulating layer. TG data supports this view since it does not show the distinct two-stage O(2) uptake characteristic of skeletal Ru. Cu K-edge EXAFS data for Ru(22)Cu(7) were unique in showing a high proportion of Ru neighbours. The spacing, d(CuRu) = 2.65 A, was that expected from a hypothetical (ideal) solid solution at this composition, but this is unlikely in such a bulk-immiscible system and Ru K-edge EXAFS failed to confirm bulk alloying. Furthermore its invariance under annealing was more indicative of an interfacial bond between bulk components, although partial alloying with retention of local order cannot entirely be ruled out. The XAS and XPS data were reconciled in a model involving surface and bulk segregation, Cu being present at both the grain exterior and in ultra-fine internal pores. This structure can be considered as the 3-dimensional analogue of the classical type. Preliminary studies in CO and H(2) oxidation were made in a DRIFTS flow reactor with on-line MS, and their activities and selectivities were compared against skeletal Ru and Cu controls, Ru/Al(2)O(3), and Au/Fe(2)O(3). All samples were active in CO oxidation above approximately 50 degrees C, showing light-off temperatures in the range 60-70 degrees C. Ru(22)Cu(7) and Ru(17)Cu(12.5) also showed good selectivities (vs. H(2) oxidation), attributed tentatively to Ru-modified Cu surfaces of varying thickness. These compositions are promising candidates to test in a (PROX) fuel processor to supply purified (CO-free) H(2) to a PEM fuel cell.

Enhanced thermoelectric performance through grain boundary engineering in quaternary chalcogenide Cu2ZnSnSe4

NASA Astrophysics Data System (ADS)

Zhu, Yingcai; Liu, Yong; Tan, Xing; Ren, Guangkun; Yu, Meijuan; Hu, Tiandou; Marcelli, Augusto; Xu, Wei

2018-04-01

Quaternary chalcogenide Cu2ZnSnSe4 (CZTSe) is a promising wide band-gap p-type thermoelectric material. The structure and thermoelectric properties of lead substituted Cu2ZnSn1-xPbxSe4 are investigated. Lead primarily exists in the framework of PbSe as demonstrated by x-ray diffraction and calculation of x-ray absorption near-edge structure spectroscopy. The second phase distributes at the boundaries of CZTSe with thickness in several hundreds of nanometer. With appropriate grain boundary engineering, the enhancement of power factor and a decrease of thermal conductivity can be achieved simultaneously. As a result, a maximum figure of merit zT of 0.45 is obtained for the sample with x=0.02 at 723K.

Localized Plasmon resonance in metal nanoparticles using Mie theory

NASA Astrophysics Data System (ADS)

Duque, J. S.; Blandón, J. S.; Riascos, H.

2017-06-01

In this work, scattering light by colloidal metal nanoparticles with spherical shape was studied. Optical properties such as diffusion efficiencies of extinction and absorption Q ext and Q abs were calculated using Mie theory. We employed a MATLAB program to calculate the Mie efficiencies and the radial dependence of electric field intensities emitted for colloidal metal nanoparticles (MNPs). By UV-Vis spectroscopy we have determined the LSPR for Cu nanoparticles (CuNPs), Ni nanoparticles (NiNPs) and Co nanoparticles (CoNPs) grown by laser ablation technique. The peaks of resonances appear in 590nm, 384nm and 350nm for CuNPs, NiNPs and CoNPs respectively suspended in water. Changing the medium to acetone and ethanol we observed a shift of the resonance peaks, these values agreed with our simulations results.

Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study.

PubMed

Hricovíni, Michal; Mazúr, Milan; Sîrbu, Angela; Palamarciuc, Oleg; Arion, Vladimir B; Brezová, Vlasta

2018-03-21

X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments.

Synthesis of Ag-Cu-Pd alloy thin films by DC-magnetron sputtering: Case study on microstructures and optical properties

NASA Astrophysics Data System (ADS)

Rezaee, Sahar; Ghobadi, Nader

2018-06-01

The present study aims to investigate optical properties of Ag-Cu-Pd alloy thin films synthesized by DC-magnetron sputtering method. The thin films are deposited on the glass and silicon substrates using Argon gas and Ag-Cu-Pd target. XRD analysis confirms the successful growth of Ag, Cu, and Pd NPs with FCC crystalline structure. Moreover, UV-visible absorption spectroscopy is applied to determine optical properties of the prepared samples which are affected by changes in surface morphology. The existence of single surface plasmon resonance (SPR) peak near 350 nm proves the formation of silver nanoparticles with a slight red shift through increasing deposition time. Ineffective thickness method (ITM) and Derivation of ineffective thickness method (DITM) are applied to extract optical band gap and transition type via absorption spectrum. SEM and AFM analyses show the distribution of near-spherical nanoparticles covering the surface of thin films. Furthermore, thickness variation affects the grain size. In addition, TEM image reveals the uniform size distribution of nanoparticles with an average particle size of about 15 nm. The findings show that increasing grain size and crystallite order along with the decrease of structural defect and disorders decrease optical band gap from 3.86 eV to 2.58 eV.

Incorporation of Copper Enhances the Anti-Ageing Property of Flame-Sprayed High-Density Polyethylene Coatings

NASA Astrophysics Data System (ADS)

Jia, Zhengmei; Huang, Jing; Gong, Yongfeng; Jin, Peipeng; Suo, Xinkun; Li, Hua

2017-02-01

High-density polyethylene (HDPE)-copper (Cu) composite coatings were prepared through depositing HDPE-Cu core-shell particles by flame spraying. The HDPE-Cu composite coatings and the HDPE coatings were aged in xenon lamp ageing testing chamber. The variations of chemical compositions and surface morphology of the coatings before and after the ageing testing were analyzed using infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and ultraviolet-visible spectrophotometer. Results show that there is no chemical composition variation in the HDPE-Cu coatings. Cracks were found on the surfaces of the HDPE coatings, while the HDPE-Cu coating shows almost intact surface morphology. These results suggest that the HDPE-Cu coatings present better anti-ageing performances than the HDPE coatings. Further assessment of the function of Cu shells on the anti-ageing property reveals that Cu shells not only enhanced the absorption of the coatings to ultraviolet, but also increased their reflectivity to visible light. Additionally, the Cu shells enhanced the decomposition temperature and thermal stability of HDPE in the composite coatings. These results give bright insight into potential anti-ageing applications of the polymer-based structures.

A Hirshfeld surface analysis, supramolecular structure and magnetic properties of a new Cu(II) complex with the 4-amino-6-methoxypyrimidine ligand

NASA Astrophysics Data System (ADS)

Nbili, W.; Kaabi, K.; Ferenc, W.; Cristovão, B.; Lefebvre, F.; Jelsch, Christian; Ben Nasr, Cherif

2017-02-01

A new Cu(II) complex with the bridge bidentate ligand 4-amino-6-methoxypyrimidine, [Cu(C5H7N3O)(H2O)(NO3)2], has been prepared at room temperature and characterized by single crystal X-ray diffraction and IR spectroscopy. The compound crystallizes in the monoclinic space group C2/c with lattice parameters a = 17.783 (4), b = 11.131 (3), c = 12.594 (3) Å, β = 117.616 (3)°, V = 2209.0 (9) Å3 and Z = 8. The Cu(II) cation is hexa-coordinated, in distorted octahedral fashion, by two nitrogen atoms of two 4-amino-6-methoxypyrimidine ligands, one water oxygen atom and three oxygen atoms of two nitrate anions. In the atomic arrangement, the organic ligands and the 6-connected Cu centers are linked with each other to give a 1-D corrugated chain running along the b-axis direction. The chains are interconnected via Osbnd H⋯O, Csbnd H⋯O, Nsbnd H⋯O hydrogen bonds to form a three dimensional network. The analysis of contacts on the Hirshfeld surface shows that the crystal packing is driven mainly by the electrostatic interactions: the coordination of Cu(II) by O and N as well as strong hydrogen bonds. The vibrational absorption bands were identified by infrared spectroscopy. Magnetic properties were also studied to characterize the complex.

An experimental investigation of localised surface plasmon resonance (LSPR) for Cu nanoparticles depending as a function of laser pulse number in Pulsed Laser Deposition

NASA Astrophysics Data System (ADS)

Gezgin, Serap Yiǧit; Kepceoǧlu, Abdullah; Kılıç, Hamdi Şükür

2017-02-01

Copper is a low cost metal and its nanoparticles have a unique optical properties such as LSPR. The location of LSPR wavelength can be tuned by controlling nanoparticles sizes and size distributions of nanoparticles, shapes and interparticle distances. This morphological changes are provided by controlling system parameters in PLD. For this work, 48000 and 36000 laser pulses from Nd:YAG laser were applied to produce Cu nanoparticle thin films. These thin films were characterised by performing UV-VIS absorption spectroscopy, Atomic Force Microscopy (AFM) analysis. When the number of laser pulse decreases, the size of Cu nanoparticles and the number of nanoparticles arriving on the substrate are reduced, and LSPR peak of thin films are red shifted depending on the geometrical shapes of the Cu nanoparticles. We have driven a conclusion in this work that LSPR properties of Cu nanoparticles can be tuned by proposed method.

CuO-Decorated ZnO Hierarchical Nanostructures as Efficient and Established Sensing Materials for H2S Gas Sensors

PubMed Central

Vuong, Nguyen Minh; Chinh, Nguyen Duc; Huy, Bui The; Lee, Yong-Ill

2016-01-01

Highly sensitive hydrogen sulfide (H2S) gas sensors were developed from CuO-decorated ZnO semiconducting hierarchical nanostructures. The ZnO hierarchical nanostructure was fabricated by an electrospinning method following hydrothermal and heat treatment. CuO decoration of ZnO hierarchical structures was carried out by a wet method. The H2S gas-sensing properties were examined at different working temperatures using various quantities of CuO as the variable. CuO decoration of the ZnO hierarchical structure was observed to promote sensitivity for H2S gas higher than 30 times at low working temperature (200 °C) compared with that in the nondecorated hierarchical structure. The sensing mechanism of the hybrid sensor structure is also discussed. The morphology and characteristics of the samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis absorption, photoluminescence (PL), and electrical measurements. PMID:27231026

Copper Nanoparticle Induced Cytotoxicity to Nitrifying Bacteria ...

EPA Pesticide Factsheets

With the inclusion of engineered nanomaterials in industrial processes and consumer products, wastewater treatments plants (WWTPs) will serve as a major sink for these emerging contaminants. Previous research has demonstrated that nanomaterials are potentially toxic to microbial communities utilized in biological wastewater treatment (BWT). Copper-based nanoparticles (CuNPs) are of particular interest based on their increasing use in wood treatment, paints, household products, coatings, and byproducts of semiconductor manufacturing. A critical step in BWT is nutrient removal via denitrification. This study examined the potential toxicity of bare and polyvinylpyrrolidone (PVP) coated CuO, and Cu2O nanoparticles, as well as Cu ions to microbial communities responsible for nitrogen removal in BWT. Inhibition was inferred from changes to the specific oxygen uptake rate (sOUR) in the absence and presence of Cu ions and CuNPs. X-ray absorption fine structure spectroscopy, with Linear Combination Fitting (LCF), was utilized to track changes to Cu speciation throughout exposure. Results indicate that the dissolution of Cu ions from CuNPs drive microbial inhibition. The presence of a PVP coating on CuNPs has little effect on inhibition. LCF fitting of the biomass combined with metal partitioning analysis supports the current hypothesis that Cu-induced cytotoxicity is primarily caused by reactive oxygen species formed from ionic Cu in solution via catalytic reaction inter

Microwave assisted synthesis of sheet-like Cu/BiVO{sub 4} and its activities of various photocatalytic conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xi; College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006; Li, Li, E-mail: qqhrll@163.com

2015-09-15

The Cu/BiVO{sub 4} photocatalyst with visible-light responsivity was prepared by the microwave-assisted hydrothermal method. The phase structures, chemical composition and surface physicochemical properties were well-characterized via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance absorption (UV–vis/DRS), scanning electron microscopy (SEM), and N{sub 2} adsorption–desorption tests. Results indicate that the crystal structure of synthetic composite materials is mainly monoclinic scheelite BiVO{sub 4}, which is not changed with the increasing doping amount of Cu. In addition, the presence of Cu not only enlarges the range of the composite materials under the visible-light response, but also increases the BET value significantly.more » Compared to pure BiVO{sub 4}, 1% Cu/BiVO{sub 4}-160 performs the highest photocatalytic activity to degrade methylene blue under the irradiation of ultraviolet, visible and simulated sunlight. In addition, the capture experiments prove that the main active species was superoxide radicals during photocatalytic reaction. Moreover, the 1% Cu/BiVO{sub 4}-160 composite shows good photocatalytic stability after three times of recycling. - Graphical abstract: A series of BiVO{sub 4} with different amounts of Cu doping were prepared by the microwave-assisted method, moreover, which performed the high photocatalytic activities to degrade methylene blue under multi-mode. - Highlights: • A series of Cu/BiVO{sub 4} with different amounts of Cu doping were prepared by microwave-assisted synthesis. • The morphologies of as-samples were different with the amount of Cu doping increased. • Compared with pure BiVO{sub 4}, as-Cu/BiVO{sub 4} showed stronger absorption in the visible light region obviously. • 1% Cu/BiVO{sub 4}-160 performed the high photocatalytic activities to degrade methylene blue under multi-mode. • OH{sup •} and h{sup +} both play important roles in the photocatalytic reaction.« less

Small hydrocarbons on metal surfaces: adsorption-induced changes in electronic and geometric structure as seen by X-ray absorption spectroscopy.

PubMed

Wöll, C

2001-03-01

Monolayers of several unsaturated and saturated hydrocarbons (ethylene, acetylene, benzene, n-hexane, cyclohexane, n-octane, n-hexatriacontane) adsorbed on a number of different metal surfaces [Cu(111), Au(111), Ru(0001) and Pt(111)] have been investigated by carbon K-edge X-ray absorption spectroscopy (XAS). Whereas the corresponding multilayer data qualitatively resemble the core-excitation spectra observed for the free molecules, generally significant modifications are observed in the monolayer data. For the saturated hydrocarbons, a strong quenching of the Rydberg R resonance at 287.7 eV and the appearance of a new broad feature at around 285.1 eV (M resonance) is observed for molecules in direct contact with the metal surfaces. In the case of the unsaturated hydrocarbons, for a number of metals, distinct new features are seen in the XAS data, revealing significant intramolecular distortions.

Multi-edge X-ray absorption spectroscopy study of road dust samples from a traffic area of Venice using stoichiometric and environmental references

NASA Astrophysics Data System (ADS)

Valotto, Gabrio; Cattaruzza, Elti; Bardelli, Fabrizio

2017-02-01

The appropriate selection of representative pure compounds to be used as reference is a crucial step for successful analysis of X-ray absorption near edge spectroscopy (XANES) data, and it is often not a trivial task. This is particularly true when complex environmental matrices are investigated, being their elemental speciation a priori unknown. In this paper, an investigation on the speciation of Cu, Zn, and Sb based on the use of conventional (stoichiometric compounds) and non-conventional (environmental samples or relevant certified materials) references is explored. This method can be useful in when the effectiveness of XANES analysis is limited because of the difficulty in obtaining a set of references sufficiently representative of the investigated samples. Road dust samples collected along the bridge connecting Venice to the mainland were used to show the potentialities and the limits of this approach.

Spin crossover in Fe(phen)2(NCS)2 complexes on metallic surfaces

NASA Astrophysics Data System (ADS)

Gruber, Manuel; Miyamachi, Toshio; Davesne, Vincent; Bowen, Martin; Boukari, Samy; Wulfhekel, Wulf; Alouani, Mebarek; Beaurepaire, Eric

2017-03-01

In this review, we give an overview on the spin crossover of Fe(phen)2(NCS)2 complexes adsorbed on Cu(100), Cu2N/Cu(100), Cu(111), Co/Cu(111), Co(100), Au(100), and Au(111) surfaces. Depending on the strength of the interaction of the molecules with the substrates, the spin crossover behavior can be drastically changed. Molecules in direct contact with non-magnetic metallic surfaces coexist in both the high- and low-spin states but cannot be switched between the two. Our analysis shows that this is due to a strong interaction with the substrate in the form of a chemisorption that dictates the spin state of the molecules through its adsorption geometry. Upon reducing the interaction to the surface either by adding a second molecular layer or inserting an insulating thin film of Cu2N, the spin crossover behavior is restored and molecules can be switched between the two states with the help of scanning tunneling microscopy. Especially on Cu2N, the two states of single molecules are stable at low temperature and thus allow the realization of a molecular memory. Similarly, the molecules decoupled from metallic substrates in the second or higher layers display thermally driven spin crossover as has been revealed by X-ray absorption spectroscopy. Finally, we discuss the situation when the complex is brought into contact with a ferromagnetic substrate. This leads to a strong exchange coupling between the Fe spin in the high-spin state and the magnetization of the substrate as deduced from spin-polarized scanning tunneling spectroscopy and ab initio calculation.

Synthesis of New Five Coordinated Copper(II) and Nickel(II) Complexes of L-Valine and Kinetic Study of Copper(II) with Calf Thymus DNA

PubMed Central

Tak, Aijaz Ahmad; Arjmand, Farukh

2002-01-01

Five coordinated novel complexes of Cu II and Ni II have been synthesized from benzil and 1,3- diaminopropane- Cu II / Ni II complex and characterized by elemental analysis, i.r., n.m.r., e.p.r, molar conductance and u.v-vis, spectroscopy. The complexes are ionic in nature and exhibit pentaeoordinated geometry around the metal ion. The reaction kinetics of C 25 H 36 N 5 O 2 CuCl with calf thymus DNA was studied by u.v-vis, spectroscopy in aqueous medium. The complex after interaction with calf thymus DNA shows shift in the absorption spectrum and hypochromicity indicating an intercalative binding mode. The K obs values have been calculated under pseudo-first order conditions. The redox behaviour of complex C 25 H 36 N 5 O 2 CuCl in the presence and in the absence of calf thymus DNA in the aqueous solution has been investigated by cyclic voltammetry. The cyclic voitammogram exhibits one quasi-reversible redox wave corresponding to Cu II / Cu I redox couple with E 1 / 2 values of -0.377 and -0.237 V respectively at a scan rate of 0.1V s - 1 .On interaction with calf thymus DNA, the complex C 25 H 36 N 5 O 2 CuCl exhibits shifts in both E p as well as in E 1 / 2 values, indicating strong binding of the complex to the calf thymus DNA. PMID:18475428

Post-formation copper-nitrogen species on carbon black: their chemical structures and active sites for oxygen reduction reaction.

PubMed

Xie, Xin; Liu, Jingjun; Li, Tuanfeng; Song, Ye; Wang, Feng

2018-05-16

Note that 3d transition metal and nitrogen co-doped carbon materials (TM-N-C) are considered as the most promising next-generation electrocatalysts alternative to precious Pt for oxygen reduction reaction (ORR). Herein, we have fabricated a Cu-N-C catalyst through directly grafting copper-nitrogen complexes composed by cuprous chloride and ammonia water onto the surface of an industrial carbon black at 500℃. In an alkaline environment, the synthesized catalyst exhibits excellent ORR catalytic activity, which is comparable to the state-of-the-art Pt/C catalyst but far exceeding that obtained by the original carbon. Moreover, the catalyst displays much better stability than the Pt/C. The enhanced ORR performance is proven to originate from the post-formation Cu(I)-N2 and Cu(II)-N4 sites at the carbon surface, as evidenced by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The possible ORR process catalyzed by these Cu-Nx species is discussed at atomic level. This work provides a simple and fast synthesis strategy for efficient TM-N-C catalysts on a large scale for energy storage and conversion systems. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Spectrum characterization and fine structure of copper phthalocyanine-doped TiO2 microcavities].

PubMed

Liu, Cheng-lin; Zhang, Xin-yi; Zhong, Ju-hua; Zhu, Yi-hua; He, Bo; Wei, Shi-qiang

2007-10-01

Copper phthalocyanine-doped TiO2 microcavities were fabricated by chemistry method. Their spectrum characterization was studied by Fourier transform infrared (FTIR) and Raman spectroscopy, and their fine structure was analyzed by X-ray absorption fine structure (XAFS). The results show that there is interaction of copper phthalocyanine (CuPc) and TiO2 microcavities after TiO2 microcavities was doped with CuPc. For example, there is absorption at 900.76 cm(-1) in FTIR spectra, and the "red shift" of both OH vibration at 3392.75 cm(-1) and CH vibration at 2848.83 cm(-1). There exist definite peak shifts and intensity changes in infrared absorption in the C-C or C-N vibration in the planar phthalocyanine ring, the winding vibration of C-H inside and C-N outside plane of benzene ring. In Raman spectrum, there are 403.4, 592.1 and 679.1 cm(-1) characterized peaks of TiO2 in CuPc-doped TiO2 microcavities, but their wave-numbers show shifts to anatase TiO2. The vibration peaks at 1586.8 and 1525.6 cm(-1) show that there exists the composite material of CuPc and TiO2. These changes are related to the plane tropism of the molecule structure of copper phthalocyanine. XAFS showed tetrahedron TiO4 structure of Ti in TiO2 microcavities doped with copper phthalocyanine, and the changes of inner "medial distances" and the surface structure of TiO2 microcavities.

Impact of S fertilizers on pore-water Cu dynamics and transformation in a contaminated paddy soil with various flooding periods.

PubMed

Yang, Jianjun; Zhu, Shenhai; Zheng, Cuiqing; Sun, Lijuan; Liu, Jin; Shi, Jiyan

2015-04-09

Impact of S fertilization on Cu mobility and transformation in contaminated paddy soils has been little reported. In this study, we investigated the dynamics and transformation of dissolved and colloidal Cu in the pore water of a contaminated paddy soil after applying ammonium sulphate (AS) and sulfur coated urea (SCU) with various flooding periods (1, 7 and 60 days). Compared to the control soil, the AS-treated soil released more colloidal and dissolved Cu over the entire flooding period, while the SCU-treated soil had lower colloidal Cu after 7-day flooding but higher colloidal and dissolved Cu after 60-day flooding. Microscopic X-ray fluorescence (μ-XRF) analysis found a close relationship between Fe and Cu distribution on soil colloids after 60-day flooding, implying the formation of colloidal Fe/Cu sulphide coprecipitates. Cu K-edge X-ray absorption near-edge structure (XANES) spectroscopy directly revealed the transformation of outer-sphere complexed Cu(II) species to Cu(II) sulphide and reduced Cu2O in the colloids of S-treated soils after 60-day flooding. These results demonstrated the great influence of S fertilization on pore-water Cu mobility by forming Cu sulphide under flooding conditions, which facilitated our understanding and control of Cu loss in contaminated paddy soils under S fertilization. Copyright © 2015 Elsevier B.V. All rights reserved.

Oxidized derivatives of Octopus vulgaris and Carcinus aestuarii hemocyanins at pH 7.5 and related models by x-ray absorption spectroscopy.

PubMed Central

Borghi, Elena; Solari, Pier Lorenzo; Beltramini, Mariano; Bubacco, Luigi; Di Muro, Paolo; Salvato, Benedetto

2002-01-01

The binuclear copper sites of the met and met-azido derivatives of Octopus vulgaris and Carcinus aestuarii hemocyanins at pH 7.5 were characterized by high-resolution x-ray absorption spectroscopy in the low energy region (XANES) and in the higher region (EXAFS). The accuracy of the analysis of the data was tested with two mononuclear and six binuclear copper(II) complexes of the poly(benzimidazole) ligand systems 2-BB, L-5,5 and L-6,6 (Casella et al., 1993, Inorg. Chem. 32:2056-2067; 1996, Inorg. Chem. 35:1101-1113). Their structural and reactivity properties are related to those of the protein's derivatives. The results obtained for those models with resolved x-ray structure (the 2-BB-aquo and azido mononuclear complexes, and the binuclear L-5,5 Cu(II)-bis(hydroxo) (Casella et al., unpublished)), extends the validity of our approach to the other poly(benzimidazole)-containing complexes and to the hemocyanin derivatives. Comparison between the protein's and the complexes' data, support a description of the met-derivatives as a five-coordinated O-bridged binuclear copper(II) center and favors, for both species, a bis(hydroxo) structure with a 3-A Cu-Cu distance. For O. vulgaris met-azido derivative a mu-1,3 bridging mode for the ligand appears the most likely. The structural situation of C. aestuarii met-azido-derivative is less clear: a mu-1,1 mode is favored, but a terminal mode cannot be excluded. PMID:12023249

Synthesis and Characterization of Diranitidinecopper(II) Sulfate Dihydrate

NASA Astrophysics Data System (ADS)

Syaima, H.; Rahardjo, S. B.; Zein, I. M.

2018-04-01

The complex of ranitidine with Cu(II) has been synthesized in 1:2-mole ratio of metal to the ligand in water. The forming of the complex was indicated by shifting of maximum wavelength from 816 nm (CuSO4·5H2O) to 626 nm (the complex). Infrared spectra indicated NO2 and NH functional group were coordinated to Cu(II). The percentage of copper in the complex measured by Atomic Absorption Spectroscopy (AAS) analysis was 7.5% indicating that formula of the complex was Cu(ranitidine)2SO4(H2O)n (n=2, 3 or 4). The electrical conductivity of Cu(II) complex in water was 71.0 Scm2mol-1 corresponding to 1:1 electrolytes. Thermogravimetric/Differential Thermal Analysis (TG/DTA) showed the presence of two molecules of H2O in the complex. UV-Vis spectra showed a transition peak on 15974 cm-1 indicating square planar geometry. The complex was paramagnetic with µeff 1.77 BM. The proposed formula of the complex was [Cu(ranitidine)2]SO4·2H2O.

Cu(II) salen complex with propylene linkage: An efficient catalyst in the formation of Csbnd X bonds (X = N, O, S) and biological investigations

NASA Astrophysics Data System (ADS)

Azam, Mohammad; Dwivedi, Sourabh; Al-Resayes, Saud I.; Adil, S. F.; Islam, Mohammad Shahidul; Trzesowska-Kruszynska, Agata; Kruszynski, Rafal; Lee, Dong-Ung

2017-02-01

The catalytic property of a mononuclear Cu(II) salen complex in Chan-Lam coupling reaction with phenyl boronic acid at room temperature is reported. The studied complex is found to be potential catalyst in the preparation of carbon-heteroatom bonds with excellent yields. The studied Cu(II) salen complex is monoclinic with cell parameters, a = 9.6807(5) (α 90°), (b = 17.2504(8) (β 112.429 (2), c = 11.1403 (6) (γ = 90°), and has distorted square planar environment around Cu(II) ion. Furthermore, there is no π⋯π interactions in the reported complex due to large distance between the centroid of aromatic rings. In addition, DNA binding study of Cu(II) salen complex by fluorescence and absorption spectroscopy is also reported. Moreover, the reported Cu(II) salen complex exhibits significant anticancer activity against MCF-7 cancer cell lines, and displays potential antimicrobial biofilm activity against P. aeruginosa, suggesting antimicrobial biofilm an important tool for suppression of resistant infections caused by P. aeruginosa.

Structural and magnetic properties of Nd0.67Ba0.33MnO3 manganites with partial replacement of Fe and Cu at Mn-site

NASA Astrophysics Data System (ADS)

Sudakshina, B.; Arun, B.; Chandrasekhar, K. Devi; Yang, H. D.; Vasundhara, M.

2018-06-01

We have investigated the structural and magnetic properties of Nd0.67Ba0.33MnO3 manganite and partial replacement of Mn with Fe and Cu compounds followed by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS) and vibrating sample magnetometer (VSM). The Rietveld refinement of XRD indicates orthorhombic crystal structure with I-mma space group for all the compounds and thus obtained lattice parameters confirm the presence of co-operative Jahn-Teller effect. XRD and XAS spectra results suggests the existence of Fe3+ in Fe-substituted compound where as a mixed state of Cu2+ and Cu3+ ions in the Cu-substituted compound. The ferromagnetic (FM) to paramagnetic (PM) transition and magnetic moment is found to decrease upon the substitution of Fe and Cu atoms because of the suppression of double exchange interaction. The theoretically obtained and experimentally determined values of effective PM moment and saturation magnetic moment confirms the presence of inhomogeneous magnetic states containing FM and antiferromagnetic clusters in all the studied compounds.

Atomic Scale Studies of Magnetic Multilayers

NASA Astrophysics Data System (ADS)

Plisch, M. J.; Muller, D. A.; Katine, J. A.; Silcox, J.; Buhrman, R. A.

1998-03-01

The structure of interfaces in magnetic multilayers plays a crucial role in determining their transport properties(S.S.P. Parkin, Phys. Rev. Lett. 71), 1641 (1993).. A scanning transmission electron microscope (STEM) which can focus a 100 kV electron beam down to 2Åis used to make spatially resolved measurements across magnetic multilayers. Previous x-ray absorption measurements suggest that the Cu d electrons play a large role in coupling the Co layers(M.G. Samant, et. al., Phys. Rev. Lett. 72), 1112 (1994).. With electon energy loss spectroscopy (EELS), information on the spatial variation of Cu d states can be obtained. Interfacial structure and bonding have been examined in multilayers with 80 ÅCu/50 ÅCo periods (with no GMR) and 9 ÅCu/13 ÅCo periods (with greater than 50% GMR). A heteroepitaxial grain structure persisting across many multilayer periods has been seen in the short period structure, but not in the long period structure. There is mixing at the Cu/Co interface and the Cu d states near the interface are significantly modified by the Co. Fe/Cr multilayers have also been examined.

Auger electron spectroscopy and x-ray photoelectron spectroscopy of the biocorrosion of copper by Gum Arabic, BCS and Pseudomonas atlantica exopolymer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jolley, J.G.; Geesey, G.G.; Hankins, M.R.

1987-01-01

Thin films (3.4 nm) of copper on germanium substrates were exposed to 10% Gum Arabic aqueous solution, 1% BCS (aqueous and simulated sea water solutions) and 0.5% Pseudomonas atlantica exopolymer (aqueous and simulated sea water solutions). Pre- and post-exposure characterization were done by Auger electron spectroscopy and x-ray photoelectron spectroscopy. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrate. Results indicate that the copper was oxidized by the Gum Arabic and BCS, and some was removed from the Cu/Ge interface by all three polymers and incorporated intomore » the polymer matrix. Thus biocorrosion of copper was exhibited by the Gum Arabic, BCS and Pseudomonas atlantica exopolymer. 14 refs., 4 figs., 3 tabs.« less

LED-CE-DOAS measurements of NO2: intercomparison with CaRDS

NASA Astrophysics Data System (ADS)

Thalman, R. M.; Washenfelder, R.; Brown, S. S.; Volkamer, R.

2009-04-01

The combination of cavity enhanced absorption spectroscopy (CEAS) with Light Emitting Diode (LED) light sources lends itself to the application of the well established Differential Optical Absorption Spectroscopy (DOAS) technique (LED-CE-DOAS). In contrast to other broad band CEAS (BB-CEAS) techniques, CE-DOAS relies only on the measurement of relative intensity changes, i.e., does not require knowledge of the light intensity in the absence of trace gases (I0). With CE-DOAS there is no necessity for sampling lines to supply air samples into a cavity, or filters to remove aerosols from the airstream, as measurements are possible in a cavity that can be open to the atmosphere. A novel LED-CE-DOAS instrument was built at CU Boulder for the sensitive and selective detection of nitrogen dioxide (NO2), glyoxal (CHOCHO), iodine oxide (IO), water, and oxygen dimers (O4). CU Boulder's LED-CE-DOAS instrument was collocated to NOAA's NO2 Cavity Ring Down (CaRDS) instrument to test different CE-DOAS data retrieval algorithms for NO2 and O4. Both instruments were collocated to sample known NO2 concentrations from the same gas manifold, and to sample atmospheric air in a parking lot. This contribution focuses on the instrument components, challenges and means to retrieve quantitative concentrations of NO2 by LED-CE-DOAS, i.e., the distortion of NO2 and O4 absorption features due to different effective path lengths induced by (1) changes in the mirror reflectivity with wavelength, and (2) changes in light extinction across the absorption bands due to differential trace gas absorption features. We demonstrate that simultaneous measurements of O4 and NO2 enable to characterize the effective pathlength in the absence and presence of NO2 and perform absolute measurements based only on relative intensity measurements. To our knowledge these are the first CEAS measurements that rely solely on relative intensity measurements.

A first-principle calculation of the XANES spectrum of Cu2+ in water

NASA Astrophysics Data System (ADS)

La Penna, G.; Minicozzi, V.; Morante, S.; Rossi, G. C.; Stellato, F.

2015-09-01

The progress in high performance computing we are witnessing today offers the possibility of accurate electron density calculations of systems in realistic physico-chemical conditions. In this paper, we present a strategy aimed at performing a first-principle computation of the low energy part of the X-ray Absorption Spectroscopy (XAS) spectrum based on the density functional theory calculation of the electronic potential. To test its effectiveness, we apply the method to the computation of the X-ray absorption near edge structure part of the XAS spectrum in the paradigmatic, but simple case of Cu2+ in water. In order to keep into account the effect of the metal site structure fluctuations in determining the experimental signal, the theoretical spectrum is evaluated as the average over the computed spectra of a statistically significant number of simulated metal site configurations. The comparison of experimental data with theoretical calculations suggests that Cu2+ lives preferentially in a square-pyramidal geometry. The remarkable success of this approach in the interpretation of XAS data makes us optimistic about the possibility of extending the computational strategy we have outlined to the more interesting case of molecules of biological relevance bound to transition metal ions.

Interfacial Engineering and Charge Carrier Dynamics in Extremely Thin Absorber Solar Cells

NASA Astrophysics Data System (ADS)

Edley, Michael

Photovoltaic energy is a clean and renewable source of electricity; however, it faces resistance to widespread use due to cost. Nanostructuring decouples constraints related to light absorption and charge separation, potentially reducing cost by allowing a wider variety of processing techniques and materials to be used. However, the large interfacial areas also cause an increased dark current which negatively affects cell efficiency. This work focuses on extremely thin absorber (ETA) solar cells that used a ZnO nanowire array as a scaffold for an extremely thin CdSe absorber layer. Photoexcited electrons generated in the CdSe absorber are transferred to the ZnO layer, while photogenerated holes are transferred to the liquid electrolyte. The transfer of photoexcited carriers to their transport layer competes with bulk recombination in the absorber layer. After charge separation, transport of charge carriers to their respective contacts must occur faster than interfacial recombination for efficient collection. Charge separation and collection depend sensitively on the dimensions of the materials as well as their interfaces. We demonstrated that an optimal absorber thickness can balance light absorption and charge separation. By treating the ZnO/CdSe interface with a CdS buffer layer, we were able to improve the Voc and fill factor, increasing the ETA cell's efficiency from 0.53% to 1.34%, which is higher than that achievable using planar films of the same material. We have gained additional insight into designing ETA cells through the use of dynamic measurements. Ultrafast transient absorption spectroscopy revealed that characteristic times for electron injection from CdSe to ZnO are less than 1 ps. Electron injection is rapid compared to the 2 ns bulk lifetime in CdSe. Optoelectronic measurements such as transient photocurrent/photovoltage and electrochemical impedance spectroscopy were applied to study the processes of charge transport and interfacial recombination. With these techniques, the extension of the depletion layer from CdSe into ZnO was determined to be vital to suppression of interfacial recombination. However, depletion of the ZnO also restricted the effective diffusion core for electrons and slowed their transport. Thus, materials and geometries should be chosen to allow for a depletion layer that suppresses interfacial recombination without impeding electron transport to the point that it is detrimental to cell performance. Thin film solar cells are another promising technology that can reduce costs by relaxing material processing requirements. CuInxGa (1-x)Se (CIGS) is a well studied thin film solar cell material that has achieved good efficiencies of 22.6%. However, use of rare elements raise concerns over the use of CIGS for global power production. CuSbS2 shares chemistry with CuInSe2 and also presents desirable properties for thin film absorbers such as optimal band gap (1.5 eV), high absorption coefficient, and Earth-abundant and non-toxic elements. Despite the promise of CuSbS2, direct characterization of the material for solar cell application is scarce in the literature. CuSbS2 nanoplates were synthesized by a colloidal hot-injection method at 220 °C in oleylamine. The CuSbS2 platelets synthesized for 30 minutes had dimensions of 300 nm by 400 nm with a thickness of 50 nm and were capped with the insulating oleylamine synthesis ligand. The oleylamine synthesis ligand provides control over nanocrystal growth but is detrimental to intercrystal charge transport that is necessary for optoelectronic device applications. Solid-state and solution phase ligand exchange of oleylamine with S2- were used to fabricate mesoporous films of CuSbS2 nanoplates for application in solar cells. Exchange of the synthesis ligand with S2- resulted in a two order of magnitude increase in 4-point probe conductivity. Photoexcited carrier lifetimes of 1.4 ns were measured by time-resolved terahertz spectroscopy, indicating potential for CuSbS2 as a solar cell absorber material.

Adsorption of Atoms of 3 d Metals on the Surfaces of Aluminum and Magnesium Oxide Films

NASA Astrophysics Data System (ADS)

Ramonova, A. G.; Kibizov, D. D.; Kozyrev, E. N.; Zaalishvili, V. B.; Grigorkina, G. S.; Fukutani, K.; Magkoev, T. T.

2018-01-01

The adsorption and formation of submonolayer structures of Ti, Cr, Fe, Ni, Cu on the surfaces of aluminum and magnesium oxide films formed on Mo(110) under ultrahigh vacuum conditions are studied via X-ray, ultraviolet photo-, and Auger electron spectroscopy (XPS, UVES, AES); spectroscopy of energy losses of high-resolution electrons (SELHRE); spectroscopy of the backscattering of low-energy ions (SBSLEI); infrared absorption spectroscopy (IAS); and the diffraction of slow electrons (DSE). Individual atoms and small clusters of all the investigated metals deposited on oxides acquire a positive charge, due presumably to interaction with surface defects. As the concentration of adatoms increases when the adsorption centers caused by defects are filled, charge transfer from adatoms to substrates is reduced. This is accompanied by further depolarization caused by the lateral interaction of adatoms.

Preparation and microwave-infrared absorption of reduced graphene oxide/Cu-Ni ferrite/Al2O3 composites

NASA Astrophysics Data System (ADS)

De-yue, Ma; Xiao-xia, Li; Yu-xiang, Guo; Yu-run, Zeng

2018-01-01

Reduced graphene oxide (RGO)/Cu-Ni ferrite/Al2O3 composite was prepared by solvothermal method, and its properties were characterized by SEM, x-ray diffraction, energy-dispersive x-ray spectroscopy and FTIR. The electromagnetic parameters in 2-18 GHz and mid-infrared (IR) spectral transmittance of the composite were measured, respectively. The results show that Cu0.7Ni0.3Fe2O4 nanoparticles with an average size of tens nanometers adsorb on surface of RGO, and meanwhile, Al2O3 nanoparticles adhere to the surface of Cu0.7Ni0.3Fe2O4 nanoparticles and RGO. The composite has both dielectric and magnetic loss mechanism. Its reflection loss is lower than -19 dB in 2-18 GHz, and the maximum of -23.2 dB occurs at 15.6 GHz. With the increasing of Al2O3 amount, its reflection loss becomes lower and the maximum moves towards low frequency slightly. Compared with RGO/Cu-Ni ferrite composites, its magnetic loss and reflection loss slightly reduce with the increasing of Al2O3 amount, and the maximum of reflection loss shifts from a low frequency to a high one. However, its broadband IR absorption is significantly enhanced owing to nano-Al2O3. Therefore, RGO/Cu-Ni ferrite/Al2O3 composites can be used as excellent broadband microwave and IR absorbing materials, and maybe have broad application prospect in electromagnetic shielding, IR absorbing and coating materials.

Synthesis, spectroscopic characterization, X-ray study and in vitro cytotoxicity of 5-hydroxycoumarin derivatives and their copper complexes

NASA Astrophysics Data System (ADS)

Ostrowska, Kinga; Maciejewska, Dorota; Drzewiecka-Antonik, Aleksandra; Klepka, Marcin T.; Wolska, Anna; Dobrzycki, Łukasz; Sztokfisz, Alicja; Czajkowska, Agnieszka; Młynarczuk-Biały, Izabela

2017-10-01

We have synthesized a series of bromo derivatives of 5-hydroxycoumarin and two new Cu(II) complexes with 6-acetyl-8-bromo-5-hydroxy-4,7-dimethylcoumarin (L2) and 6-acetyl-3,8-dibromo-5-hydroxy-4,7-dimethylcoumarin (L3) ligands, designed as potential active compounds against human cancer cell lines. The elemental analysis, mass spectroscopy, NMR and infrared spectroscopy have been used for basic characterization of analyzed compounds. The X-ray crystal structure analysis for one representative organic compound, 3,6,8-tribromo-5-hydroxy-4,7-dimethylcoumarin (c) has been performed. It has shown that coumarin system is nearly planar and the Br⋯Br interaction is a very characteristic feature of the molecular association for organic ligands. The complexes, Cu(L2)2·3H2O and Cu(L3)(ClO4)·2.5H2O, have been found as four-coordinated and contain copper in the +2 oxidation state according to X-ray absorption spectroscopy. All the compounds have been screened in vitro for their cytotoxic activity against mouse fibroblast and human prostate cancer cells. The coordination products of brominated ligands have shown to be more active than the free ligands and demonstrate significant in-vitro cytotoxicity against human prostate cancer cells (DU145).

Optical properties of trinuclear metal chalcogenolate complexes - room temperature NIR fluorescence in [Cu2Ti(SPh)6(PPh3)2].

PubMed

Kühn, Michael; Lebedkin, Sergei; Weigend, Florian; Eichhöfer, Andreas

2017-01-31

The optical properties of four isostructural trinuclear chalcogenolato bridged metal complexes [Cu 2 Sn(SPh) 6 (PPh 3 ) 2 ], [Cu 2 Sn(SePh) 6 (PPh 3 ) 2 ], [Ag 2 Sn(SPh) 6 (PPh 3 ) 2 ] and [Cu 2 Ti(SPh) 6 (PPh 3 ) 2 ] have been investigated by absorption and photoluminescence spectroscopy and time-dependent density functional theory (TDDFT) calculations. All copper-tin compounds demonstrate near-infrared (NIR) phosphorescence at ∼900-1100 nm in the solid state at low temperature, which is nearly absent at ambient temperature. Stokes shifts of these emissions are found to be unusually large with values of about 1.5 eV. The copper-titanium complex [Cu 2 Ti(SPh) 6 (PPh 3 ) 2 ] also shows luminescence in the NIR at 1090 nm but with a much faster decay (τ ∼ 10 ns at 150 K) and a much smaller Stokes shift (ca. 0.3 eV). Even at 295 K this fluorescence is found to comprise a quantum yield as high as 9.5%. The experimental electronic absorption spectra well correspond to the spectra simulated from the calculated singlet transitions. In line with the large Stokes shifts of the emission spectra the calculations reveal for the copper-tin complexes strong structural relaxation of the excited triplet states whereas those effects are found to be much smaller in the case of the copper-titanium complex.

Grain Growth in Cu2ZnSnS4 Thin Films Using Sn Vapor Transport for Photovoltaic Applications

NASA Astrophysics Data System (ADS)

Toyama, Toshihiko; Konishi, Takafumi; Seo, Yuichi; Tsuji, Ryotaro; Terai, Kengo; Nakashima, Yuto; Okamoto, Hiroaki; Tsutsumi, Yasuo

2013-07-01

Cu2ZnSnS4 thin films containing grains grown using Sn vapor transport (TVT) were investigated. Structural characterization revealed that the grain sizes were equal to or larger than the film thickness (1-4 µm) and significantly larger than those in the case of growth without TVT (60 nm). Furthermore, no phase separation was detected. Photothermal diffraction spectroscopy revealed that the optical absorption coefficient was very low in the subgap region, 7×101 cm-1, suggesting the suppression of defect formation. Finally, a TVT-processed thin film was used as an absorber in a solar cell, and a conversion efficiency of 6.9% was achieved.

Local X-ray magnetic circular dichroism study of Fe/Cu(111) using a tunneling smart tip

DOE PAGES

DiLullo, Andrew; Shirato, Nozomi; Cummings, Marvin; ...

2016-01-28

Localized spectroscopy with simultaneous topographic, elemental and magnetic information is presented. A synchrotron X-ray scanning tunneling microscope has been employed for the local study of the X-ray magnetic circular dichroism at the FeL 2,3-edges of a thin iron film grown on Cu(111). Polarization-dependent X-ray absorption spectra have been obtained through a tunneling smart tip that serves as a photoelectron detector. In contrast to conventional spin-polarized scanning tunneling microscopy, X-ray excitations provide magnetic contrast even with a non-magnetic tip. Intensity variations in the photoexcited tip current point to chemical variations within a single magnetic Fe domain.

Local X-ray magnetic circular dichroism study of Fe/Cu(111) using a tunneling smart tip.

PubMed

DiLullo, Andrew; Shirato, Nozomi; Cummings, Marvin; Kersell, Heath; Chang, Hao; Rosenmann, Daniel; Miller, Dean; Freeland, John W; Hla, Saw-Wai; Rose, Volker

2016-03-01

Localized spectroscopy with simultaneous topographic, elemental and magnetic information is presented. A synchrotron X-ray scanning tunneling microscope has been employed for the local study of the X-ray magnetic circular dichroism at the Fe L2,3-edges of a thin iron film grown on Cu(111). Polarization-dependent X-ray absorption spectra have been obtained through a tunneling smart tip that serves as a photoelectron detector. In contrast to conventional spin-polarized scanning tunneling microscopy, X-ray excitations provide magnetic contrast even with a non-magnetic tip. Intensity variations in the photoexcited tip current point to chemical variations within a single magnetic Fe domain.

Local X-ray magnetic circular dichroism study of Fe/Cu(111) using a tunneling smart tip

PubMed Central

DiLullo, Andrew; Shirato, Nozomi; Cummings, Marvin; Kersell, Heath; Chang, Hao; Rosenmann, Daniel; Miller, Dean; Freeland, John W.; Hla, Saw-Wai; Rose, Volker

2016-01-01

Localized spectroscopy with simultaneous topographic, elemental and magnetic information is presented. A synchrotron X-ray scanning tunneling microscope has been employed for the local study of the X-ray magnetic circular dichroism at the Fe L 2,3-edges of a thin iron film grown on Cu(111). Polarization-dependent X-ray absorption spectra have been obtained through a tunneling smart tip that serves as a photoelectron detector. In contrast to conventional spin-polarized scanning tunneling microscopy, X-ray excitations provide magnetic contrast even with a non-magnetic tip. Intensity variations in the photoexcited tip current point to chemical variations within a single magnetic Fe domain. PMID:26917146

Spin orbit and tetragonal crystalline field interaction in the valence band of CuInSe2-related ordered vacancy compound CuIn7Se12

NASA Astrophysics Data System (ADS)

Reena Philip, Rachel; Pradeep, B.; Shripathi, T.

2005-04-01

Thin films of the off-tie-line ordered vacancy compound CuIn7Se12 were deposited on optically flat glass substrates by multi-source co-evaporation method. The preliminary structural, compositional and morphological characterizations were done using X-ray diffraction, energy dispersive X-ray analysis and atomic force microscopy. The X-ray diffraction data were further analysed applying the Nelson-Riley method and CTB plus = experiment rule, respectively, for lattice constants (a = 5.746 Å and c = 11.78 Å) and bond length estimations (RCu-Se = 2.465 Å and RIn-Se = 2.554 Å). A detailed analysis of the optical absorption spectra of the compound, which exhibited a three-fold optical absorption structure in the fundamental gap region, yielded three characteristic direct energy gaps at 1.37, 1.48(7) and 1.72(8) eV indicative of valence band splitting, which were evaluated using Hopfield's quasi-cubic model. The 0.04 eV increase in spin-orbit splitting parameter of the compound (0.27 eV) compared to that of CuInSe2 (0.23 eV) is found to be suggestive of the smaller contribution of Cu d orbitals to hybridization (determined by the linear hybridization model) in this Cu-deficient compound. Spectral response spectra exhibit, in addition to a maximum around 1.34 ± 0.03 eV, two other defect transition peaks near 1.07 and 0.85 eV. The binding energies of Cu, In and Se in the compound were determined using X-ray photoelectron spectroscopy.

Resonance Raman spectra of the copper-sulfur chromophores in Achromobacter cycloclastes nitrite reductase.

PubMed

Dooley, D M; Moog, R S; Liu, M Y; Payne, W J; LeGall, J

1988-10-15

Resonance Raman spectroscopy at ambient temperature and 77 K has been used to probe the structures of the copper sites in Achromobacter cycloclastes nitrite reductase. This enzyme contains three copper ions per protein molecule and has two principal electronic absorption bands with lambda max values of 458 and 585 nm. Comparisons between the resonance Raman spectra of nitrite reductase and blue copper proteins establish that both the 458 and 585 nm bands are associated with Cu(II)-S(Cys) chromophores. A histidine ligand probably is also present. Different sets of vibrational frequencies are observed with 457.9 nm (ambient) or 476.1 nm (77 K) excitation as compared with 590 nm (ambient) or 593 nm (77 K) excitation. Excitation profiles indicate that the 458 and 585 nm absorption bands are associated with separate [Cu(II)-S(Cys)N(His)] sites or with inequivalent and uncoupled cysteine ligands in the same site. The former possibility is considered to be more likely.

Incorporation of copper nanoparticles into paper for point-of-use water purification.

PubMed

Dankovich, Theresa A; Smith, James A

2014-10-15

As a cost-effective alternative to silver nanoparticles, we have investigated the use of copper nanoparticles in paper filters for point-of-use water purification. This work reports an environmentally benign method for the direct in situ preparation of copper nanoparticles (CuNPs) in paper by reducing sorbed copper ions with ascorbic acid. Copper nanoparticles were quickly formed in less than 10 min and were well distributed on the paper fiber surfaces. Paper sheets were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, and atomic absorption spectroscopy. Antibacterial activity of the CuNP sheets was assessed for by passing Escherichia coli bacteria suspensions through the papers. The effluent was analyzed for viable bacteria and copper release. The CuNP papers with higher copper content showed a high bacteria reduction of log 8.8 for E. coli. The paper sheets containing copper nanoparticles were effective in inactivating the test bacteria as they passed through the paper. The copper levels released in the effluent water were below the recommended limit for copper in drinking water (1 ppm). Copyright © 2014 Elsevier Ltd. All rights reserved.

Investigations on Cu2+-substituted Ni-Zn ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Amarjeet; Kumar, Vinod

2016-11-01

CuxNi(1-x)/2Zn(1-x)/2Fe2O4 (x = 0.1, 0.3 and 0.5) nanoparticles were prepared by chemical co-precipitation method. The developed nanoparticles were characterized for structural properties by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Peak position in the X-ray diffraction pattern confirmed the single spinel phase of the developed particles. Infrared (IR) spectroscopy in mid-IR range showed the presence of characteristic absorption bands corresponding to octahedral and tetrahedral bonds in the spinel structure of prepared samples. Thermo-gravimetric analysis (TGA) measurements showed a considerable weight loss in the developed samples above 700∘C. Frequency dependence of the electrical properties of the developed material pellets was studied in the frequency range of 1 kHz-5 MHz. Temperature dependence of the dielectric constant of Cu0.1Ni0.45Zn0.45Fe2O4 was studied at different temperatures, i.e. at 425, 450 and 475 K, in the frequency range of 1 kHz-5 MHz. It was found that the electrical conductivity decreases with increasing Cu2+ ion content while it increases with the increase in temperature.

Mercury mobilization in a flooded soil by incorporation into metallic copper and metal sulfide nanoparticles.

PubMed

Hofacker, Anke F; Voegelin, Andreas; Kaegi, Ralf; Kretzschmar, Ruben

2013-07-16

Mercury is a highly toxic priority pollutant that can be released from wetlands as a result of biogeochemical redox processes. To investigate the temperature-dependent release of colloidal and dissolved Hg induced by flooding of a contaminated riparian soil, we performed laboratory microcosm experiments at 5, 14, and 23 °C. Our results demonstrate substantial colloidal Hg mobilization concomitant with Cu prior to the main period of sulfate reduction. For Cu, we previously showed that this mobilization was due to biomineralization of metallic Cu nanoparticles associated with suspended bacteria. X-ray absorption spectroscopy at the Hg LIII-edge showed that colloidal Hg corresponded to Hg substituting for Cu in the metallic Cu nanoparticles. Over the course of microbial sulfate reduction, colloidal Hg concentrations decreased but continued to dominate total Hg in the pore water for up to 5 weeks of flooding at all temperatures. Transmission electron microscopy (TEM) suggested that Hg became associated with Cu-rich mixed metal sulfide nanoparticles. The formation of Hg-containing metallic Cu and metal sulfide nanoparticles in contaminated riparian soils may influence the availability of Hg for methylation or volatilization processes and has substantial potential to drive Hg release into adjacent water bodies.

Activated carbon-supported CuO nanoparticles: a hybrid material for carbon dioxide adsorption

NASA Astrophysics Data System (ADS)

Boruban, Cansu; Esenturk, Emren Nalbant

2018-03-01

Activated carbon-supported copper(II) oxide (CuO) nanoparticles were synthesized by simple impregnation method to improve carbon dioxide (CO2) adsorption capacity of the support. The structural and chemical properties of the hybrid material were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (https://www.google.com.tr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CCsQFjAC&url=http%3A%2F%2Fwww.intertek.com%2Fanalytical-laboratories%2Fxrd%2F&ei=-5WZVYSCHISz7Aatqq-IAw&usg=AFQjCNFBlk-9wqy49foh8tskmbD-GGbG9g&sig2=eKrhYjO75rl_Id2sLGpq4w&bvm=bv.96952980,d.bGg) (XRD), X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS), and Brunauer-Emmett-Teller (BET) analyses. The analyses showed that CuO nanoparticles are well-distributed on the activated carbon surface. The CO2 adsorption behavior of the activated carbon-supported CuO nanoparticles was observed by thermogravimetric analysis (TGA), temperature programmed desorption (TPD), Fourier transform infrared (FTIR), and BET analyses. The results showed that CuO nanoparticle loading on activated carbon led to about 70% increase in CO2 adsorption capacity of activated carbon under standard conditions (1 atm and 298 K). The main contributor to the observed increase is an improvement in chemical adsorption of CO2 due to the presence of CuO nanoparticles on activated carbon.

Uptake, Distribution, and Transformation of CuO NPs in a Floating Plant Eichhornia crassipes and Related Stomatal Responses.

PubMed

Zhao, Jian; Ren, Wenting; Dai, Yanhui; Liu, Lijiao; Wang, Zhenyu; Yu, Xiaoyu; Zhang, Junzhe; Wang, Xiangke; Xing, Baoshan

2017-07-05

Engineered nanoparticles (NPs) are being released into aquatic environments with their increasing applications. In this work, we investigated the interaction of CuO NPs with a floating plant, water hyacinth (Eichhornia crassipes). CuO NPs (50 mg/L) showed significant growth inhibition on both roots and shoots of E. crassipes after 8-day exposure, much higher than that of the bulk CuO particles (50 mg/L) and their corresponding dissolved Cu 2+ ions (0.30 mg/L). Scanning electron and light microscopic observations showed that the root caps and meristematic zone of E. Crassipes were severely damaged after CuO NP exposure, with disordered cell arrangement and a destroyed elongation zone of root tips. It is confirmed that CuO NPs could be translocated to shoot from both roots and submerged leaves. As detected by X-ray absorption near-edge spectroscopy analysis (XANES), CuO NPs were observed in roots, submerged leaves, and emerged leaves. Cu 2 S and other Cu species were also detected in these tissues, providing solid evidence of the transformation of CuO NPs. In addition, stomatal closure was observed during CuO NPs-leaf contact, which was induced by the production of H 2 O 2 and increased Ca level in leaf guard cells. These findings are helpful for better understanding the fate of NPs in aquatic plants and related biological responses.

A Bispidol Chelator with a Phosphonate Pendant Arm: Synthesis, Cu(II) Complexation, and 64Cu Labeling.

PubMed

Gillet, Raphaël; Roux, Amandine; Brandel, Jérémy; Huclier-Markai, Sandrine; Camerel, Franck; Jeannin, Olivier; Nonat, Aline M; Charbonnière, Loïc J

2017-10-02

Here we present the synthesis and characterization of a new bispidine (3,7-diazabicyclo[3.3.1]nonane) ligand with N-methanephosphonate substituents (L 2 ). Its physicochemical properties in water, as well as those of the corresponding Cu(II) and Zn(II) complexes, have been evaluated by using UV-visible absorption spectroscopy, potentiometry, 1 H and 31 P NMR, and cyclic voltammetry. Radiolabeling experiments with 64 Cu II have been carried out, showing excellent radiolabeling properties. Quantitative complexation was achieved within 60 min under stoichiometric conditions, at room temperature and in the nanomolar concentration range. It was also demonstrated that the complexation occurred below pH 2. Properties have been compared to those of the analogue bispidol bearing a N-methanecarboxylate substituent (L 1 ). Although both systems meet the required criteria to be used as new chelator for 64/67 Cu in terms of the kinetics of formation, thermodynamic stability, selectivity for Cu(II), and kinetic inertness regarding redox- or acid-assisted decomplexation processes, substitution of the carboxylic acid function by the phosphonic moiety is responsible for a significant increase in the thermodynamic stability of the Cu(II) complex (+2 log units for pCu) and also leads to an increase in the radiochemical yields with 64 Cu II which is quantitative for L 2 .

Enhanced photocatalytic hydrogen evolution activity of CuInS{sub 2} loaded TiO{sub 2} under solar light irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Changjiang; Xi, Zhenhao; Fang, Wenzhang

2015-03-15

In this paper, p–n type CuInS{sub 2}/TiO{sub 2} particles were prepared in ethylenediamine by the solvothermal method. The microstructural properties of the synthesized p–n type catalysts were characterized by X-ray diffraction (XRD) in order to confirm the existence of crystalline CuInS{sub 2} on the surface of TiO{sub 2}, which was also confirmed by X-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM) images provided the detailed morphological properties about the CuInS{sub 2}/TiO{sub 2} heterostructure. UV–vis diffuse reflectance spectroscopy (UV–vis DRS) was used to investigate the optical properties of the CuInS{sub 2}/TiO{sub 2} particles. The DRS results indicated that both the p–nmore » type structure and CuInS{sub 2} acting as a sensitizer can enhance significantly the absorption of UV and visible light. The photocatalytic activities of the CuInS{sub 2}/TiO{sub 2} particles were evaluated by hydrogen evolution reactions using Xe-lamp irradiation as a simulated solar light source. The greatly enhanced photocatalytic activity of hydrogen evolution under simulated solar light is about ~7 fold higher than that of pure commercial TiO{sub 2} (Degussa P25). - Graphical abstract: The heterojunction structure of CuInS{sub 2}/TiO{sub 2} promoted the efficiency of photoinduced charge carrier transfer and highly inherited the recombination of activated electrons and holes. - Highlight: • CuInS{sub 2}/TiO{sub 2} was prepared by a one-step solvothermal method. • 2.5% CuInS{sub 2}/TiO{sub 2} has the highest activity and keeps the activity stable. • Heterojunction structure of sample promoted the separation of electrons and holes.« less

Structural and magnetic properties of epitaxial delafossite CuFeO2 thin films grown by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Senty, Tess; Joshi, Toyanath; Trappen, Robbyn; Zhou, Jinling; Chen, Song; Ferrari, Piero; Borisov, Pavel; Song, Xueyan; Holcomb, Mikel; Bristow, Alan; Cabrera, Alejandro; Lederman, David

2015-03-01

Growth of pure phase delafossite CuFeO2 thin films on Al2O3 (00.1) substrates by pulsed laser deposition was systematically investigated as function of growth temperature and oxygen pressure. X-ray diffraction, transmission electron microscopy, Raman scattering, and x-ray absorption spectroscopy confirmed the existence of the delafossite phase. Infrared reflectivity spectra determined a band edge at 1.15 eV, in agreement with the bulk delafossite data. Magnetization measurements on CuFeO2 films demonstrated a phase transition at TC = 15K, which agrees with the first antiferromagnetic transition at 14K in the bulk CuFeO2. Low temperature magnetic phase is best described by commensurate, weak ferromagnetic spin ordering along the c-axis. This work was supported by a Research Challenge Grant from the West Virginia Higher Education Policy Commission (HEPC.dsr.12.29) and the Microelectronics Advanced Research Corporation (Contract #2013-MA-2382) at WVU. Work at PUC was supported by FONDECyT.

Synthesis, Characterization and the Corrosion Inhibition Study of Two Schiff Base Ligands Derived From Urea and Thiourea and Their Complexes with Cu(II) and Hg(II) Ions

NASA Astrophysics Data System (ADS)

Alwan, Wasan Mohammed

2018-05-01

The research includes synthesis of [L1] and [L2] Schiff base ligands by the reaction of vanillin with urea and thiourea respectively in 2:1 mol ratio. The two ligands were reacted with CuII ion in 1:2 mol ratio and HgII ion in 1:1 mol ratio. The prepared compounds have been identified by FTIR, U.V-Vis, 1H-NMR (L1, L2 and HgII complex) spectroscopies, microelemental analysis (C.H.N.S), magnetic susceptibility measurements, atomic absorption, chloride content along with conductivity and melting point measurements. According to applied characterization methods, the proposed general formulas of CuII and HgII complexes were [Cu2LnCl4] and [HgLnCl]Cl, respectively, (where n = 1, 2). The ability of corrosion inhibition with two ligands and their cupper complexes has been studied in diluted hydrochloric acid media.

Auto-combustion synthesis and characterization of Mg doped CuAlO{sub 2} nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agrawal, Shraddha, E-mail: shraddhaa32@gmail.com; Parveen, Azra; Naqvi, A. H.

2015-06-24

The synthesis of pure and Mg doped Copper aluminumoxide CuAlO{sub 2}nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO{sub 2} sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO{sub 2} has been studied over a wide range of frequencies by using complex impedance spectroscopy.Themore » variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.« less

Auto-combustion synthesis and characterization of Mg doped CuAlO2 nanoparticles

NASA Astrophysics Data System (ADS)

Agrawal, Shraddha; Parveen, Azra; Naqvi, A. H.

2015-06-01

The synthesis of pure and Mg doped Copper aluminumoxide CuAlO2nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO2 sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO2 has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.

Bioaccessibility of Ca, Cu, Fe, Mg, Zn, and crude protein in beef, pork and chicken after thermal processing.

PubMed

Menezes, Eveline A; Oliveira, Aline F; França, Celia J; Souza, Gilberto B; Nogueira, Ana Rita A

2018-02-01

The bioaccessibility of Ca, Cu, Fe, Mg, Zn, and crude protein was evaluated after submitting beef, pork, and chicken to five different thermal treatments. The bioaccessibility of crude protein and metals were simulated by using in vitro enzymatic digestion with a gastric fluid solution and dialysability approach. Inductively coupled plasma optical spectrometry was used to quantify the dialyzable fraction and the total mineral content after microwave-assisted digestion. Graphite furnace atomic absorption spectrometry quantified Cu in chicken dialyzable fraction. The increase of temperature and heat exposure period decreased the protein bioaccessibility. Considering the total and dialyzable fraction, beef is an important source of Cu, Fe, Mg, and Zn to the human diet. The results of Fourier-transform infrared spectroscopy indicated physical changes in the treated samples related to protein denaturation, which was probably responsible for the decreased bioaccessibility of minerals and protein, mainly at higher temperatures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Structure and magnetic/electrochemical properties of Cu-doped BiFeO3 nanoparticles prepared by a simple solution method

NASA Astrophysics Data System (ADS)

Khajonrit, Jessada; Phumying, Santi; Maensiri, Santi

2016-06-01

BiFe1- x Cu x O3 (x = 0, 0.05, 0.1, 0.2, and 0.3) nanoparticles were prepared by a simple solution method. The prepared nanoparticles were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) method analysis using the Barret-Joyner-Halenda (BJH) model, and X-ray absorption spectroscopy (XAS). Magnetization properties were obtained using a vibrating sample magnetometer (VSM) at room temperature. Magnetization was clearly enhanced by increasing Cu content and decreasing particle size. Zero-field-cooled (ZFC) and field-cooled (FC) temperature-dependent magnetization measurements showed that blocking temperature increased with increasing Cu content. Electrochemical properties were investigated by cyclic voltammetry (CV) and the galvanostatic charge-discharge (GCD) method. The performance of the fabricated supercapacitor was improved for the BiFe0.95Cu0.05O3 electrode. The highest specific capacitance was 568.13 F g-1 at 1 A g-1 and the capacity retention was 77.13% after 500 cycles.

Insight into the core-shell structures of Cu-In-S microspheres

NASA Astrophysics Data System (ADS)

Wochnik, Angela S.; Frank, Anna; Heinzl, Christoph; Häusler, Jonas; Schneider, Julian; Hoffmann, Ramona; Matich, Sonja; Scheu, Christina

2013-12-01

In this study we report about the inner and outer structure of CuInS2 microspheres which might be used e.g. in pastes for simple, low-cost solar cell preparation, as well as in electrodes for light-driven water splitting. The microspheres are synthesized via a mild, template-free solvothermal synthesis route and characterised by electron and focused ion beam microscopy, X-ray diffraction, inductively coupled plasma atomic emission and energy dispersive X-ray spectroscopy. The investigations of cross sections prepared by focused ion beam showed that the spheres consist of compact cores and flaky surface structures. Depending on the reaction time, the core possesses a stoichiometric or Cu-rich chemical composition surrounded by an In-rich shell. The flaky surface always comprises a stoichiometric composition in tetragonal chalcopyrite crystal structure, whereas the other areas additionally show minor contributions of CuS, and CuInS2 in hexagonal wurtzite structure. The presence of different phases can be beneficial for future applications since they offer different absorption behaviour in the visible range.

Electron paramagnetic resonance in Cu-doped ZnO

NASA Astrophysics Data System (ADS)

Buchheit, R.; Acosta-Humánez, F.; Almanza, O.

2016-04-01

In this work, ZnO and Cu-doped ZnO nanoparticles (Zn1-xCuxO, x = 3%), with a calcination temperature of 500∘C were synthesized using the sol-gel method. The particles were analyzed using atomic absorption spectroscopy (AAS), X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) at X-band, measurement in a temperature range from 90 K to room temperature. AAS confirmed a good correspondence between the experimental doping concentration and the theoretical value. XRD reveals the presence of ZnO phase in hexagonal wurtzite structure and a nanoparticle size for the samples synthesized. EPR spectroscopy shows the presence of point defects in both samples with g-values of g = 1.959 for shallow donors and g = 2.004 for ionized vacancies. It is important when these materials are required have been used as catalysts, as suggested that it is not necessary prepare them at higher temperature. A simulation of the Cu EPR signal using an anisotropic spin Hamiltonian was performed and showed good coincidence with the experimental spectra. It was shown that Cu2+ ions enter interstitial octahedral sites of orthorhombic symmetry in the wurtzite crystal structure. Temperature dependence of the EPR linewidth and signal intensity shows a paramagnetic behavior of the sample in the measurement range. A Néel temperature TN = 78 ± 19 K was determined.

Colorimetric determination of glutathione in human serum and cell lines by exploiting the peroxidase-like activity of CuS-polydopamine-Au composite.

PubMed

Wang, Yanying; Liu, Yaqin; Ding, Fang; Zhu, Xiaoyan; Yang, Li; Zou, Ping; Rao, Hanbing; Zhao, Qingbiao; Wang, Xianxiang

2018-06-07

In this study, we developed a simple colorimetric approach to detect glutathione (GSH). The proposed approach is based on the ability of CuS-PDA-Au composite material to catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to ox-TMB to induce a blue color with an absorption peak centered at 652 nm. However, the introduction of GSH can result in a decrease in oxidized TMB; similarly, it can combine with Au nanoparticles (Au NPs) on the surface of CuS-PDA-Au composite material. Both approaches can result in a fading blue color and a reduction of the absorbance at 652 nm. Based on this above, we proposed a technique to detect GSH quantitatively and qualitatively through UV-Vis spectroscopy and naked eye, respectively. This approach demonstrates a low detection limit of 0.42 μM with a broad detection range of 5 × 10 -7 -1 × 10 -4  M with the assistance of UV-Vis spectroscopy. More importantly, this approach is convenient and rapid. This method was successfully applied to GSH detection in human serum and cell lines. Graphical abstract A colorimetric approach has been developed by exploiting the peroxidase-like activity of CuS-polydopamine-Au composite for sensitive glutathione detection.

Copper-65-absorption by men fed intrinsically and extrinsically labeled whole wheat bread

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, P.E.; Lykken, G.I.

Six men were fed a diet composed of conventional foods with all bread as whole wheat bread. Intrinsically labeled /sup 65/Cu bread (containing 6.5 ppm Cu and 48 atom % /sup 65/Cu) was substituted for unlabeled bread for 3 days, and stools were collected for 24 days. Extrinsically labeled bread was then substituted for 3 days and another 24-day stool collection made. /sup 65/Cu excretion was measured by mass spectrometry. Mean Cu intake was 1.10 mg of Cu/day. Average Cu balance was /minus/0.06 /+-/ 0.08 mg/day. Average absorption of the intrinsic copper was 72.2 /+-/ 9.3% and of extrinsic Cumore » 64.2 /+-/ 5.8%. The ratio of extrinsic to intrinsic absorption was 0.906 /+-/ 0.164. Absorption of intrinsic and extrinsic tracers did not differ significantly (p > 0.05) by a paired t-test, and the ratio (E/I) was not significantly different from 1. Use of extrinsic Cu tracers to assess Cu absorption is supported by these results.« less

Heavy-metal detectors based on modified ferrite nanoparticles

PubMed Central

Klekotka, Urszula; Wińska, Ewelina; Zambrzycka-Szelewa, Elżbieta; Satuła, Dariusz

2018-01-01

In this work, we analyze artificial heavy-metal solutions with ferrite nanoparticles. Measurements of adsorption effectiveness of different kinds of particles, pure magnetite or magnetite doped with calcium, cobalt, manganese, or nickel ions, were carried out. A dependence of the adsorption efficiency on the composition of the inorganic core has been observed. Ferrites surfaces were modified by phthalic anhydride (PA), succinic anhydride (SA), acetic anhydride (AA), 3-phosphonopropionic acid (3-PPA), or 16-phosphohexadecanoic acid (16-PHDA) to compare the adsorption capability of the heavy metals Cd, Cu and Pb. The obtained nanoparticles were structurally characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Mössbauer spectroscopy. The amounts of Cd, Cu and Pb were measured out by atomic absorption spectroscopy (AAS) and energy dispersive X-ray (EDX) as comparative techniques. The performed study shows that SA linker appears to be the most effective in the adsorption of heavy metals. Moreover, regarding the influence of the composition of the inorganic core on the detection ability, the most effective ferrite Mn0.5Fe2.5O4 was selected for discussion. The highest heavy-metal adsorption capability and universality was observed for SA as a surface modifier. PMID:29600137

Heavy-metal detectors based on modified ferrite nanoparticles.

PubMed

Klekotka, Urszula; Wińska, Ewelina; Zambrzycka-Szelewa, Elżbieta; Satuła, Dariusz; Kalska-Szostko, Beata

2018-01-01

In this work, we analyze artificial heavy-metal solutions with ferrite nanoparticles. Measurements of adsorption effectiveness of different kinds of particles, pure magnetite or magnetite doped with calcium, cobalt, manganese, or nickel ions, were carried out. A dependence of the adsorption efficiency on the composition of the inorganic core has been observed. Ferrites surfaces were modified by phthalic anhydride (PA), succinic anhydride (SA), acetic anhydride (AA), 3-phosphonopropionic acid (3-PPA), or 16-phosphohexadecanoic acid (16-PHDA) to compare the adsorption capability of the heavy metals Cd, Cu and Pb. The obtained nanoparticles were structurally characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Mössbauer spectroscopy. The amounts of Cd, Cu and Pb were measured out by atomic absorption spectroscopy (AAS) and energy dispersive X-ray (EDX) as comparative techniques. The performed study shows that SA linker appears to be the most effective in the adsorption of heavy metals. Moreover, regarding the influence of the composition of the inorganic core on the detection ability, the most effective ferrite Mn 0.5 Fe 2.5 O 4 was selected for discussion. The highest heavy-metal adsorption capability and universality was observed for SA as a surface modifier.

Study of the interaction of proteins with curcumin and SDS and its analytical application

NASA Astrophysics Data System (ADS)

Wang, Feng; Yang, Jinghe; Wu, Xia; Liu, Shufang

2005-09-01

It is found that protein and sodium dodecyl sulphonate (SDS) can enhance resonance light scattering (RLS) of curcumin (CU). Based on this phenomenon, a new quantitative method for protein in aqueous solution has been developed. In the BR (pH 3.5) buffer, the RLS intensity of CU-SDS system is greatly enhanced by protein. The enhanced RLS is proportional to the concentration of protein in the range of 0.00020-20.0 μg ml -1 for bovine serum albumin (BSA) and 0.00040-1.0 μg ml -1 for human serum albumin (HSA) and their detection limits are 0.16 and 0.041 ng ml -1, respectively. An actual sample is satisfactorily determined. In addition, the interaction mechanism between protein and CU-SDS is also studied by using multi-techniques such as RLS, absorption spectroscopy and fluorescence, zeta potential assay measurement.

Effect of copper and nickel doping on the optical and structural properties of ZnO

NASA Astrophysics Data System (ADS)

Muǧlu, G. Merhan; Sarıtaş, S.; ćakıcı, T.; Şakar, B.; Yıldırım, M.

2017-02-01

The present study is focused on the Cu doped ZnO and Ni doped ZnO dilute magnetic semiconductor thin films. ZnO:Cu and ZnO:Ni thin films were grown by Chemically Spray Pyrolysis (CSP) method on glass substrates. Optical analysis of the films was done spectral absorption and transmittance measurements by UV-Vis double beam spectrophotometer technique. The structure, morphology, topology and elemental analysis of ZnO:Cu and ZnO:Ni dilute magnetic thin films were investigated by X-ray diffraction (XRD), Raman Analysis, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) techniques, respectively. Also The magnetic properties of the ZnO:Ni thin film was investigated by vibrating sample magnetometer (VSM) method. VSM measurements of ZnO:Ni thin film showed that the ferromagnetic behavior.

Ultrafast hole carrier relaxation dynamics in p-type CuO nanowires

PubMed Central

2011-01-01

Ultrafast hole carrier relaxation dynamics in CuO nanowires have been investigated using transient absorption spectroscopy. Following femtosecond pulse excitation in a non-collinear pump-probe configuration, a combination of non-degenerate transmission and reflection measurements reveal initial ultrafast state filling dynamics independent of the probing photon energy. This behavior is attributed to the occupation of states by photo-generated carriers in the intrinsic hole region of the p-type CuO nanowires located near the top of the valence band. Intensity measurements indicate an upper fluence threshold of 40 μJ/cm2 where carrier relaxation is mainly governed by the hole dynamics. The fast relaxation of the photo-generated carriers was determined to follow a double exponential decay with time constants of 0.4 ps and 2.1 ps. Furthermore, time-correlated single photon counting measurements provide evidence of three exponential relaxation channels on the nanosecond timescale. PMID:22151927

Growth and characterization of chalcostibite CuSbSe2 thin films for photovoltaic application

NASA Astrophysics Data System (ADS)

Tiwari, Kunal J.; Vinod, Vijay; Subrahmanyam, A.; Malar, P.

2017-10-01

Bulk copper antimony selenide was synthesized using mechanical alloying from the elemental precursors. Phase formation in milled powders was studied using x-ray diffraction (XRD) and Raman spectroscopy studies. The synthesized bulk source after cold compaction was used as source material for thin film deposition by e-beam evaporation. Thin film deposition was carried out at various e-beam current values (Ib ∼30, 40 and 50 mA) and at a substrate temperature of 200 °C. Near stoichiometric CuSbSe2 thin films were obtained for Ib values closer to 50 mA and post annealing at a temperature of 380 °C for 1 h. Thin films deposited using above conditions were found to exhibit an absorption coefficient (α) values of >105 cm-1 and a band gap value ∼1.18 eV that is closer to the reported band gap for CuSbSe2 compound.

Cadmium, Chromium, and Copper Concentration plus Semen-Quality in Environmental Pollution Site, China

PubMed Central

LI, Yan; GAO, Qiaoyan; LI, Mingcai; LI, Mengyang; GAO, Xueming

2014-01-01

Abstract Background The environmental pollution is one of the factors contributing to the decrease of sperm quality for human beings. The aim of this study was to assess cadmium (Cd), chromium (Cr), and copper (Cu) concentration of man in environmental pollution site, and explore relationships between men exposure to Cd, Cr, and Cu and semen-quality parameters in environmental pollution site. Methods Ninety five men were recruited through pollution area and controls in 2011. We measured semen quality using Computer-aided Semen Quality Analysis, and Cd, Cr, and Cu levels in seminal plasma using Graphite Gurnace Atomic Absorption Spectroscopy. Spearman rank correlation analysis was used to evaluate the correlation between Cd, Cr and Cu concentration in seminal plasma and semen quality. Results The mean of seminal plasma Cd, Cr, and Cu values in pollution area was higher than the controls. Seminal plasma Cr values displayed a significant negative correlation with total motility and normomorph sperm rate. Seminal plasma Cu values also displayed a negative correlation with normomorph sperm rate. Conclusions Male reproductive health may be threatened by environmental pollution, and it may be influence local population diathesis. PMID:26060677

Probing the CZTS/CdS heterojunction utilizing photoelectrochemistry and x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Turnbull, Matthew J.; Vaccarello, Daniel; Wong, Jonathan; Yiu, Yun Mui; Sham, Tsun-Kong; Ding, Zhifeng

2018-04-01

The importance of renewable resources is becoming more and more influential on research due to the depletion of fossil fuels. Cost-effective ways of harvesting solar energy should also be at the forefront of these investigations. Cu2ZnSnS4 (CZTS) solar cells are well within the frame of these goals, and a thorough understanding of how they are made and processed synthetically is crucial. The CZTS/CdS heterojunction was examined using photoelectrochemistry and synchrotron radiation (SR) spectroscopy. These tools provided physical insights into this interface that was formed by the electrophoretic deposition of CZTS nanocrystals and chemical bath deposition (CBD) of CdS for the respective films. It was discovered that CBD induced a change in the local and long range environment of the Zn in the CZTS lattice, which was detrimental to the photoresponse. X-ray absorption near-edge structures and extended X-ray absorption fine structures (EXAFSs) of the junction showed that this change was at an atomic level and was associated with the coordination of oxygen to zinc. This was confirmed through FEFF fitting of the EXAFS and through IR spectroscopy. It was found that this change in both photoresponse and the Zn coordination can be reversed with the use of low temperature annealing. Investigating CZTS through SR techniques provides detailed structural information of minor changes from the zinc perspective.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisenhart, Reed J.; Carlson, Rebecca K.; Clouston, Laura J.

Heterobimetallic complexes that pair cobalt and copper were synthesized and characterized by a suite of physical methods, including X-ray diffraction, X-ray anomalous scattering, cyclic voltammetry, magnetometry, electronic absorption spectroscopy, electron paramagnetic resonance, and quantum chemical methods. Both Cu(II) and Cu(I) reagents were independently added to a Co(II) metalloligand to provide (py3tren)CoCuCl (1-Cl) and (py3tren)CoCu(CH3CN) (2-CH3CN), respectively, where py3tren is the triply deprotonated form of N,N,N-tris(2-(2-pyridylamino)ethyl)amine. Complex 2-CH3CN can lose the acetonitrile ligand to generate a coordination polymer consistent with the formula “(py3tren)CoCu” (2). One-electron chemical oxidation of 2-CH3CN with AgOTf generated (py3tren)CoCuOTf (1-OTf). The Cu(II)/Cu(I) redox couple for 1-OTf andmore » 2-CH3CN is reversible at -0.56 and -0.33 V vs Fc+/Fc, respectively. The copper oxidation state impacts the electronic structure of the heterobimetallic core, as well as the nature of the Co–Cu interaction. Quantum chemical calculations showed modest electron delocalization in the (CoCu)+4 state via a Co–Cu σ bond that is weakened by partial population of the Co–Cu σ antibonding orbital. By contrast, no covalent Co–Cu bonding is predicted for the (CoCu)+3 analogue, and the d-electrons are fully localized at individual metals.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eisenhart, Reed J.; Carlson, Rebecca K.; Clouston, Laura J.

Heterobimetallic complexes that pair cobalt and copper were synthesized and characterized by a suite of physical methods, including X-ray diffraction, X-ray anomalous scattering, cyclic voltammetry, magnetometry, electronic absorption spectroscopy, electron paramagnetic resonance, and quantum chemical methods. Both Cu(II) and Cu(I) reagents were independently added to a Co(II) metalloligand to provide (py 3tren)CoCuCl (1-Cl) and (py 3tren)CoCu(CH 3CN) (2-CH 3CN), respectively, where py3tren is the triply deprotonated form of N,N,N-tris(2-(2-pyridylamino)ethyl)amine. Complex 2-CH 3CN can lose the acetonitrile ligand to generate a coordination polymer consistent with the formula “(py3tren)CoCu” (2). One-electron chemical oxidation of 2-CH 3CN with AgOTf generated (py 3tren)CoCuOTf (1-OTf).more » The Cu(II)/Cu(I) redox couple for 1-OTf and 2-CH 3CN is reversible at -0.56 and -0.33 V vs Fc +/Fc, respectively. The copper oxidation state impacts the electronic structure of the heterobimetallic core, as well as the nature of the Co–Cu interaction. Quantum chemical calculations showed modest electron delocalization in the (CoCu) +4 state via a Co–Cu σ bond that is weakened by partial population of the Co–Cu σ antibonding orbital. By contrast, no covalent Co–Cu bonding is predicted for the (CoCu) +3 analogue, and the d-electrons are fully localized at individual metals.« less

Enhancement in light harvesting ability of photoactive layer P3HT: PCBM using CuO nanoparticles

NASA Astrophysics Data System (ADS)

Tiwari, D. C.; Dwivedi, Shailendra Kumar; Dipak, Pukhrambam; Chandel, Tarun

2018-05-01

In this paper, we have synthesized CuO nanoparticles via precipitation method and incorporated CuO nanoparticles in the P3HT-poly (3-hexyl) thiophene: PCBM-[6, 6]-phenyl-C61-butyric acid methyl ester heterogeneous blend. The ratio of P3HT to CuO in the blend was varied, while maintaining the fixed ratio of PCBM. The UV-visible absorption spectra of P3HT: PCBM photoactive layer containing different weight percentages of CuO nanoparticles showed a clear enhancement in the photo absorption of the active layer. The absorption band starts from 310 nm to 750 nm for P3HT: CuO (NPs):PCBM (0.5:0.5:1). This shows that incorporation of CuO nanoparticles leads to larger absorption band. In addition, the X-ray diffraction (XRD) shows improvement in P3HT crystallinity and the better formation of CuO nanostructures.

Quantitative analysis of Al-Si alloy using calibration free laser induced breakdown spectroscopy (CF-LIBS)

NASA Astrophysics Data System (ADS)

Shakeel, Hira; Haq, S. U.; Aisha, Ghulam; Nadeem, Ali

2017-06-01

The quantitative analysis of the standard aluminum-silicon alloy has been performed using calibration free laser induced breakdown spectroscopy (CF-LIBS). The plasma was produced using the fundamental harmonic (1064 nm) of the Nd: YAG laser and the emission spectra were recorded at 3.5 μs detector gate delay. The qualitative analysis of the emission spectra confirms the presence of Mg, Al, Si, Ti, Mn, Fe, Ni, Cu, Zn, Sn, and Pb in the alloy. The background subtracted and self-absorption corrected emission spectra were used for the estimation of plasma temperature as 10 100 ± 300 K. The plasma temperature and self-absorption corrected emission lines of each element have been used for the determination of concentration of each species present in the alloy. The use of corrected emission intensities and accurate evaluation of plasma temperature yield reliable quantitative analysis up to a maximum 2.2% deviation from reference sample concentration.

Multi-edge X-ray absorption spectroscopy study of road dust samples from a traffic area of Venice using stoichiometric and environmental references.

PubMed

Valotto, Gabrio; Cattaruzza, Elti; Bardelli, Fabrizio

2017-02-15

The appropriate selection of representative pure compounds to be used as reference is a crucial step for successful analysis of X-ray absorption near edge spectroscopy (XANES) data, and it is often not a trivial task. This is particularly true when complex environmental matrices are investigated, being their elemental speciation a priori unknown. In this paper, an investigation on the speciation of Cu, Zn, and Sb based on the use of conventional (stoichiometric compounds) and non-conventional (environmental samples or relevant certified materials) references is explored. This method can be useful in when the effectiveness of XANES analysis is limited because of the difficulty in obtaining a set of references sufficiently representative of the investigated samples. Road dust samples collected along the bridge connecting Venice to the mainland were used to show the potentialities and the limits of this approach. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of metal-laden water via portable X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Pearson, Delaina; Weindorf, David C.; Chakraborty, Somsubhra; Li, Bin; Koch, Jaco; Van Deventer, Piet; de Wet, Jandre; Kusi, Nana Yaw

2018-06-01

A rapid method for in-situ elemental composition analysis of metal-laden water would be indispensable for studying polluted water. Current analytical lab methods to determine water quality include flame atomic absorption spectrometry (FAAS), atomic absorption spectrophotometry (AAS), electrothermal atomic absorption spectrometry (EAAS), and inductively coupled plasma (ICP) spectroscopy. However only two field methods, colorimetry and absorptiometry, exist for elemental analysis of water. Portable X-ray fluorescence (PXRF) spectrometry is an effective method for elemental analysis of soil, sediment, and other matrices. However, the accuracy of PXRF is known to be affected while scanning moisture-laden soil samples. This study sought to statistically establish PXRF's predictive ability for various elements in water at different concentrations relative to inductively coupled plasma atomic emission spectroscopy (ICP-AES). A total of 390 metal-laden water samples collected from leaching columns of mine tailings in South Africa were analyzed via PXRF and ICP-AES. The PXRF showed differential effectiveness in elemental quantification. For the collected water samples, the best relationships between ICP and PXRF elemental data were obtained for K and Cu (R2 = 0.92). However, when scanning ICP calibration solutions with elements in isolation, PXRF results indicated near perfect agreement; Ca, K, Fe, Cu and Pb produced an R2 of 0.99 while Zn and Mn produced an R2 of 1.00. The utilization of multiple PXRF (stacked) beams produced stronger correlation to ICP relative to the use of a single beam in isolation. The results of this study demonstrated the PXRF's ability to satisfactorily predict the composition of metal-laden water as reported by ICP for several elements. Additionally this study indicated the need for a "Water Mode" calibration for the PXRF and demonstrates the potential of PXRF for future study of polluted or contaminated waters.

Tuning Catalytic Performance through a Single or Sequential Post-Synthesis Reaction(s) in a Gas Phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shan, Junjun; Zhang, Shiran; Choksi, Tej

2016-12-05

Catalytic performance of a bimetallic catalyst is determined by geometric structure and electronic state of the surface or even the near-surface region of the catalyst. Here we report that single and sequential postsynthesis reactions of an as-synthesized bimetallic nanoparticle catalyst in one or more gas phases can tailor surface chemistry and structure of the catalyst in a gas phase, by which catalytic performance of this bimetallic catalyst can be tuned. Pt–Cu regular nanocube (Pt–Cu RNC) and concave nanocube (Pt–Cu CNC) are chosen as models of bimetallic catalysts. Surface chemistry and catalyst structure under different reaction conditions and during catalysis weremore » explored in gas phase of one or two reactants with ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The newly formed surface structures of Pt–Cu RNC and Pt–Cu CNC catalysts strongly depend on the reactive gas(es) used in the postsynthesis reaction(s). A reaction of Pt–Cu RNC-as synthesized with H2 at 200 °C generates a near-surface alloy consisting of a Pt skin layer, a Cu-rich subsurface, and a Pt-rich deep layer. This near-surface alloy of Pt–Cu RNC-as synthesized-H2 exhibits a much higher catalytic activity in CO oxidation in terms of a low activation barrier of 39 ± 4 kJ/mol in contrast to 128 ± 7 kJ/mol of Pt–Cu RNC-as synthesized. Here the significant decrease of activation barrier demonstrates a method to tune catalytic performances of as-synthesized bimetallic catalysts. A further reaction of Pt–Cu RNC-as synthesized-H2 with CO forms a Pt–Cu alloy surface, which exhibits quite different catalytic performance in CO oxidation. It suggests the capability of generating a different surface by using another gas. The capability of tuning surface chemistry and structure of bimetallic catalysts was also demonstrated in restructuring of Pt–Cu CNC-as synthesized.« less

A model of the interfacial processes inhibiting the environmental degradation of Al-Cu alloys

NASA Astrophysics Data System (ADS)

Kearns, Jeffery Robert

A better understanding of the composition and structure of chemically treated Al alloy surfaces is necessary to devise new, more environmentally benign, coating systems for aircraft. In this work, the surface of AA2024-T3, as well as analogs for constituent intermetallic compounds (IMC), were examined at various stages of the Al alloy pretreatment and chromate conversion coating (CCC) process. A complement of techniques were used: imaging and dyanmic Secondary Ion Mass Spectroscopy (SIMS), Variable-Angle X-ray Photoelectron Spectroscopy (VA/XPS), Synchrotron Infrared Microspectroscopy (SIRS), X-ray Absorption Spectroscopy (XAS), and Electrochemical Impedance Spectroscopy (EIS). The water and hydrocarbons in commercial CCC destabilized Cr(VI) during exposure to soft x-rays. However, it was possible to prevent photochemical reduction with the ultra-clean vacuum pumping practice recently developed at Stony Brook. The type of pretreatment used prior to chromate conversion coating influenced the extent of IMC removal, Cu (re)distribution, and surface activity. Cu(I) was observed on all the chemically treated surfaces. Samples pretreated in Sanchem 1000 while galvanically coupled to a Pt mesh had a more desirable distribution of Cu for subsequent processing. Chromate reduction was not a significant factor in CCC aging over a 24-hr period, but surface dehydration and structural change were correlated and causative. Imaging SIMS revealed heterogeneities in the CCC that varied laterally with IMC in the alloy substrate. These regions were depleted in compounds containing Cr, F, and CN. Cu was found at localized sites in the CCC contact surface. Cyano groups were bound as Cr(IlI)-CNFe(H). The chromate available for CCC repair was located on matrix regions through the entire bulk of the CCC. The presence of residual contaminants (e.g. cleaning agents, metal working fluid, ink) affected the distribution of activator compounds (e.g. ferricyanide) in a CCC. The cyanide complex (Cr(Ill)-Fe-CN6) was found in the CCC bulk not just at the outermost surface. A new model for CCC on Al-Cr alloys is proposed. The model is based on the sol-gel-like nascent CCC that limits the transport of IMC dissolution products.

Effect of isovalent dopants on photodegradation ability of ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Khaparde, Rohini; Acharya, Smita

2016-06-01

Isovalent (Mn, Cd, Cu, Co)-doped-ZnS nanoparticles having size vary in between 2 to 5 nm are synthesized by co-precipitation route. Their photocatalytic activity for decoloration of Cango Red and Malachite Green dyes is tested in visible radiation under natural conditions. Structural and morphological features of the samples are investigated by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and UVsbnd Vis spectrometer. Single phase zinc blende structure of as-synthesized undoped and doped-ZnS is confirmed by XRD and revealed by Rietveld fitting. SEM and TEM images show ultrafine nanoparticles having size in the range of 2 to 5 nm. UV-Vis absorption spectra exhibit blue shift in absorption edge of undoped and doped ZnS as compared to bulk counterpart. The photocatalytic activity as a function of dopant concentration and irradiation time is systematically studied. The rate of de-coloration of dyes is detected by UVsbnd Vis absorption spectroscopy and organic dye mineralization is confirmed by table of carbon (TOC) study. The photocatalytic activity of Mn-doped ZnS is highest amongst all dopants; however Co as a dopant is found to reduce photocatalytic activity than pure ZnS.

X-Ray Absorption Spectroscopy of Electrochemically Generated Species

DTIC Science & Technology

1989-01-27

constructed from gold minigrid, colloidal graphite, and reticulated vitreous carbon (RVC). The use of gold minigrid electrodes has been demonstrated for...jBF n (bipy= 2,2’-ipyridine, dmp= 2,9-dimethvl- 1,10-phenanthroline) in solution at reticulated vitreous carbon electrodes, and incorporated in...Fe(bipy)3(C104)2, Ru(bipy)3Cl2, and Cu(drp)2BF4 (bipy= 2,2’-bipyridine, dmp= 2, 9-dimethyl-l,10-phenanthroline) in solution at reticulated vitreous

C-H oxidation and chelation of a dipyrromethane mediated rapid colorimetric naked-eye Cu(ii) chemosensor.

PubMed

Rajmohan, Rajamani; Ayaz Ahmed, Khan Behlol; Sangeetha, Sampathkumar; Anbazhagan, Veerappan; Vairaprakash, Pothiappan

2017-09-08

Copper(ii) ion mediated C-H oxidation of dipyrromethanes (DPMs) to the corresponding dipyrrins followed by complexation invoked the selective sensing of copper(ii) ions in aqueous solutions. On the addition of copper, the colour of the DPM solution instantaneously changes from yellow to pink with the detection limit of 0.104 μM measured by absorption spectroscopy, whereas visible colour changes could be observed by the naked eye for concentrations as low as 3 μM.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, Merrin S.; Dillon, Carolyn T.; Vogt, Stefan

Metal toxicity to aquatic organisms depends on the speciation of the metal and its binding to the critical receptor site(s) (biotic ligand) of the organism. The intracellular nature of the biotic ligand for Cu in microalgal cells was investigated using the high elemental sensitivity of microprobe synchrotron radiation X-ray fluorescence (SR-XRF) and X-ray absorption near-edge spectroscopy (XANES). The marine microalgae, Ceratoneis closterium, Phaeodactylum tricornutum, and Tetraselmis sp. were selected based on their varying sensitivities to Cu (72-h 50% population growth inhibitions of 8–47 μg Cu/L). Intracellular Cu in control cells was similar for all three species (2.5–3.2 × 10–15 gmore » Cu/cell) and increased 4-fold in C. closterium and Tetraselmis sp. when exposed to copper, but was unchanged in P. tricornutum (72-h exposure to 19, 40, and 40 μg Cu/L, respectively). Whole cell microprobe SR-XRF identified endogenous Cu in the central compartment (cytoplasm) of control (unexposed) cells. After Cu exposure, Cu was colocated with organelles/granules dense in P, S, Ca, and Si and this was clearly evident in thin sections of Tetraselmis sp. XANES indicated coexistence of Cu(I) and Cu(II) in control and Cu-exposed cells, with the Cu ligand (e.g., phytochelatin) in P. tricornutum different from that in C. closterium and Tetraselmis sp. Here, this study supports the hypothesis that Cu(II) is reduced to Cu(I) and that polyphosphate bodies and phytochelatins play a significant role in the internalization and detoxification of Cu in marine microalgae.« less

Multispectroscopic and molecular modeling studies on the interaction of copper-ibuprofenate complex with bovine serum albumin (BSA).

PubMed

Shiri, Farshad; Rahimi-Nasrabadi, Mehdi; Ahmadi, Farhad; Ehrlich, Hermann

2018-05-31

Bovine serum albumin (BSA) represents the well recognized model protein for investigations of diverse intermolecular reactions in studies on pharmacological activities of modern drugs. In the present work, the interaction between copper ibuprofenate ([Cu2(IBU)4]) and BSA under simulative physiological conditions was investigated by the using of diverse spectral methods including fluorescence, UV-vis absorption, CD spectroscopy and also molecular docking. The obtained results showed that there was a strong fluorescence quenching of BSA by [Cu2(IBU)4] (2.964E+4 M -1 at room temperature). Using the continuous variation method, a single class of binding sites, (1:1), for [Cu2(IBU)4] on BSA was put in evidence. The Stern-Volmer analysis of fluorescence quenching data shows the presence of the static quenching mechanism. The binding constants K b were calculated and the thermodynamic parameters ∆G°, ∆H° and ∆S° were given. The obtained thermodynamic values and the change observed in the alpha-helical content signature suggests that hydrogen bonding and hydrophobic forces play a major role in the [Cu2(IBU)4]-BSA binding interaction. Site marker competitive experiments indicated that the binding of [Cu2(IBU)4] to BSA primarily took place in sub-domain IIA that this observation were substantiated by molecular docking studies. The results of CD and UV-vis spectroscopy showed for the first time that the presence of [Cu2(IBU)4] increased the ɑ-helical content of BSA (from 48.56% to 55.71%) and conformational changes of BSA molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

High covalence in CuSO4 and the radicalization of sulfate: an X-ray absorption and density functional study.

PubMed

Szilagyi, Robert K; Frank, Patrick; DeBeer George, Serena; Hedman, Britt; Hodgson, Keith O

2004-12-27

Sulfur K-edge X-ray absorption spectroscopy (XAS) of anhydrous CuSO(4) reveals a well-resolved preedge transition feature at 2478.8 eV that has no counterpart in the XAS spectra of anhydrous ZnSO(4) or copper sulfate pentahydrate. Similar but weaker preedge features occur in the sulfur K-edge XAS spectra of [Cu(itao)SO(4)] (2478.4 eV) and [Cu[(CH(3))(6)tren]SO(4)] (2477.7 eV). Preedge features in the XAS spectra of transition metal ligands are generally attributed to covalent delocalization of a metal d-orbital hole into a ligand-based orbital. Copper L-edge XAS of CuSO(4) revealed that 56% of the Cu(II) 3d hole is delocalized onto the sulfate ligand. Hybrid density functional calculations on the two most realistic models of the covalent delocalization pathways in CuSO(4) indicate about 50% electron delocalization onto the sulfate oxygen-based 2p orbitals; however, at most 14% of that can be found on sulfate sulfur. Both experimental and computational results indicated that the high covalence of anhydrous CuSO(4) has made sulfate more like the radical monoanion, inducing an extensive mixing and redistribution of sulfur 3p-based unoccupied orbitals to lower energy in comparison to sulfate in ZnSO(4). It is this redistribution, rather than a direct covalent interaction between Cu(II) and sulfur, that is the origin of the observed sulfur XAS preedge feature. From pseudo-Voigt fits to the CuSO(4) sulfur K-edge XAS spectrum, a ground-state 3p character of 6% was quantified for the orbital contributing to the preedge transition, in reasonable agreement with the DFT calculation. Similar XAS fits indicated 2% sulfur 3p character for the preedge transition orbitals in [Cu(itao)SO(4)] and [Cu[(CH(3))(6)tren]SO(4)]. The covalent radicalization of ligands similar to sulfate, with consequent energy redistribution of the virtual orbitals, represents a new mechanism for the induction of ligand preedge XAS features. The high covalence of the Cu sites in CuSO(4) was found to be similar to that of Cu sites in oxidized cupredoxins, including its anistropic nature, and can serve as the simplest inorganic examples of intramolecular electron-transfer processes.

Adsorption of Cu(II) from aqueous solution on sulfuric acid treated palygorskite

NASA Astrophysics Data System (ADS)

Niu, Yan-Ning; Yuan, Yuan; Gao, Wei-Xin; Qian, Sheng; Sun, Wen

2018-03-01

The absorption behavior of Cu2+ from aqueous solution on sulfuric acid treated palygorskite were investigated, the results showed that palygorskite had high absorption ability for Cu2+ from aqueous solution. Effects of the shaking time, pH and the copper ion concentration on the removal rate were discussed. The absorption behavior of Cu2+ could be well imitated by the Langmuir isothermal equation.

Terahertz time-domain spectroscopy and quantitative analysis of metal gluconates.

PubMed

Li, Shaoxian; Yang, Jingqi; Zhao, Hongwei; Yang, Na; Jing, Dandan; Zhang, Jianbing; Li, Qingnuan; Han, Jiaguang

2015-01-01

A series of metal gluconates (Na(+), K(+), Mg(2+), Ca(2+), Fe(2+), Cu(2+), and Zn(2+)) were investigated by terahertz (THz) time-domain spectroscopy. The absorption coefficients and refractive indices of the samples were obtained in the frequency range of 0.5-2.6 THz. The gluconates showed distinct THz characteristic fingerprints, and the dissimilarities reflect their different structures, hydrogen-bond networks, and molecular interactions. In addition, some common features were observed among these gluconates, and the similarities probably come from the similar carbohydrate anion group. The X-ray powder diffraction measurements of these metal gluconates were performed, and the copper(II) gluconate was found to be amorphous, corresponding to the monotonic increase feature in the THz absorption spectrum. The results suggest that THz spectroscopy is sensitive to molecular structure and physical form. Binary and ternary mixtures of different gluconates were quantitatively analyzed based on the Beer-Lambert law. A chemical map of a tablet containing calcium D-gluconate monohydrate and α-lactose in the polyethylene host was obtained by THz imaging. The study shows that THz technology is a useful tool in pharmaceutical research and quality control applications.

Interaction between Diethyldithiocarbamate and Cu(II) on Gold in Non-Cyanide Wastewater

PubMed Central

Ly, Nguyễn Hoàng; Nguyen, Thanh Danh; Zoh, Kyung-Duk; Joo, Sang-Woo

2017-01-01

A surface-enhanced Raman scattering (SERS) detection method for environmental copper ions (Cu2+) was developed according to the vibrational spectral change of diethyldithiocarbamate (DDTC) on gold nanoparticles (AuNPs). The ultraviolet-visible (UV-Vis) absorption spectra indicated that DDTC formed a complex with Cu2+, showing a prominent peak at ~450 nm. We found Raman spectral changes in DDTC from ~1490 cm−1 to ~1504 cm−1 on AuNPs at a high concentration of Cu2+ above 1 μM. The other ions of Zn2+, Pb2+, Ni2+, NH4+, Mn2+, Mg2+, K+, Hg2+, Fe2+, Fe3+, Cr3+, Co2+, Cd2+, and Ca2+ did not produce such spectral changes, even after they reacted with DDTC. The electroplating industrial wastewater samples were tested under the interference of highly concentrated ions of Fe3+, Ni2+, and Zn2+. The Raman spectroscopy-based quantification of Cu2+ ions was able to be achieved for the wastewater after treatment with alkaline chlorination, whereas the cyanide-containing water did not show any spectral changes, due to the complexation of the cyanide with the Cu2+ ions. A micromolar range detection limit of Cu2+ ions could be achieved by analyzing the Raman spectra of DDTC in the cyanide-removed water. PMID:29140287

Interaction between Diethyldithiocarbamate and Cu(II) on Gold in Non-Cyanide Wastewater.

PubMed

Ly, Nguyễn Hoàng; Nguyen, Thanh Danh; Zoh, Kyung-Duk; Joo, Sang-Woo

2017-11-15

A surface-enhanced Raman scattering (SERS) detection method for environmental copper ions (Cu 2+ ) was developed according to the vibrational spectral change of diethyldithiocarbamate (DDTC) on gold nanoparticles (AuNPs). The ultraviolet-visible (UV-Vis) absorption spectra indicated that DDTC formed a complex with Cu 2+ , showing a prominent peak at ~450 nm. We found Raman spectral changes in DDTC from ~1490 cm -1 to ~1504 cm -1 on AuNPs at a high concentration of Cu 2+ above 1 μM. The other ions of Zn 2+ , Pb 2+ , Ni 2+ , NH₄⁺, Mn 2+ , Mg 2+ , K⁺, Hg 2+ , Fe 2+ , Fe 3+ , Cr 3+ , Co 2+ , Cd 2+ , and Ca 2+ did not produce such spectral changes, even after they reacted with DDTC. The electroplating industrial wastewater samples were tested under the interference of highly concentrated ions of Fe 3+ , Ni 2+ , and Zn 2+ . The Raman spectroscopy-based quantification of Cu 2+ ions was able to be achieved for the wastewater after treatment with alkaline chlorination, whereas the cyanide-containing water did not show any spectral changes, due to the complexation of the cyanide with the Cu 2+ ions. A micromolar range detection limit of Cu 2+ ions could be achieved by analyzing the Raman spectra of DDTC in the cyanide-removed water.

Size tunable elemental copper nanoparticles: extracellular synthesis by thermoanaerobic bacteria and capping molecules

DOE PAGES

Jang, Gyoung Gug; Jacobs, Christopher B.; Gresback, Ryan G.; ...

2014-11-10

Bimodal sized elemental copper (Cu) nanoparticles (NPs) were synthesized from inexpensive oxidized copper salts by an extracellular metal-reduction process using anaerobic Thermoanaerobacter sp. X513 bacteria in aqueous solution. The bacteria nucleate NPs outside of the cell, and they control the Cu2+ reduction rate to form uniform crystallites with an average diameter of 1.75 0.46 m after 3-day incubation. To control the size and enhance air stability of Cu NPs, the reaction mixtures were supplemented with nitrilotriacetic acid as a chelator, and the surfactant capping agents oleic acid, oleylamine, ascorbic acid, or L-cysteine. Time-dependent UV-visible absorption measurements and XPS studies indicatedmore » well-suspended, bimodal colloidal Cu NPs (70 150 and 5 10 nm) with extended air-stability up to 300 min and stable Cu NP films surfaces with 14% oxidation after 20 days. FTIR spectroscopy suggested that these capping agents were effectively adsorbed on the NP surface providing oxidation resistance in aqueous and dry conditions. Compared to previously reported Cu NP syntheses, this biological process substantially reduced the requirement for hazardous organic solvents and chemical reducing agents, while reducing the levels of Cu oxide impurities in the product. This process was highly reproducible and scalable from 0.01 to 1-L batches.« less

[Effect of Characteristic Variable Extraction on Accuracy of Cu in Navel Orange Peel by LIBS].

PubMed

Li, Wen-bing; Yao, Ming-yin; Huang, Lin; Chen, Tian-bing; Zheng, Jian-hong; Fan, Shi-quan; Liu Mu-hua HE, Mu-hua; Lin, Jin-long; Ouyang, Jing-yi

2015-07-01

Heavy metals pollution in foodstuffs is more and more serious. It is impossible to satisfy the modern agricultural development by conventional chemical analysis. Laser induced breakdown spectroscopy (LIBS) is an emerging technology with the characteristic of rapid and nondestructive detection. But LIBS' s repeatability, sensitivity and accuracy has much room to improve. In this work, heavy metal Cu in Gannan Navel Orange which is the Jiangxi specialty fruit will be predicted by LIBS. Firstly, the navel orange samples were contaminated in our lab. The spectra of samples were collected by irradiating the peel by optimized LIBS parameters. The laser energy was set as 20 mJ, delay time of Spectral Data Gathering was set as 1.2 micros, the integration time of Spectral data gathering was set as 2 ms. The real concentration in samples was obtained by AAS (atom absorption spectroscopy). The characteristic variables Cu I 324.7 and Cu I 327.4 were extracted. And the calibration model was constructed between LIBS spectra and real concentration about Cu. The results show that relative error of the predicted concentrations of three relational model were 7.01% or less, reached a minimum of 0.02%, 0.01% and 0.02% respectively. The average relative errors were 2.33%, 3.10% and 26.3%. Tests showed that different characteristic variables decided different accuracy. It is very important to choose suitable characteristic variable. At the same time, this work is helpful to explore the distribution of heavy metals between pulp and peel.

Spectroscopic studies of trimetoxypropylsilane and bis(trimethoxysilyl)ethane sol-gel coatings on aluminum and copper.

PubMed

Li, Ying-Sing; Tran, Tuan; Xu, Yue; Vecchio, Nicolas E

2006-11-01

Trimethoxypropylsilane (TMPS) and bis(trimethoxysilyl)ethane (BTMSE) were used as surface modifiers of metal vie the sol-gel process and dip coating. In addition to the single coating of Al, Cu and Sn, double treatments of Al were also conducted by combining coatings with these sol-gels in different sequences. Reflection and absorption infrared spectroscopy (RAIR) was employed to characterize and to trace the proceeding of the sol-gel process of the films. It was found that the silanol condensation occurs in the coating films on Al and the covalent linkage exists between the TMPS film and copper surface. From the assigned vibration modes, two conformers were identified in pure TMPS, TMPS sol-gel and coated film. A series of dip coating experiments with different concentrations of TMPS sol-gel was conducted, and the results from the collected RAIR spectra of the coated samples suggested that the coated Cu consistently has a better RAIR spectrum than that of the coated Al. The TMPS sol-gel appeared to have a better affinity to Cu than to Al. The temperature effect and the aging effect in the coating films were studied. X-ray photoelectronic spectroscopy (XPS) was employed to characterize the coated film, and the XPS data confirm the formation of the siloxane film from the silane coupling agents (SCA). Electrochemical impedance spectra (EIS) have been collected for bare Al and Cu, BTMSE sol-gel coated Al, and TMPS sol-gel coated Cu in 0.15M NaCl solution. The corresponding electronic circuit parameters have been determined to match the experimental EIS data.

Evaluation of dog bones in the indirect assessment of environmental contamination with trace elements.

PubMed

Lanocha, Natalia; Kalisinska, Elzbieta; Kosik-Bogacka, Danuta I; Budis, Halina

2012-06-01

The aim of this paper was to determine the level of five elements, two essential for life [zinc (Zn) and copper (Cu)] and three distinctly toxic [lead (Pb), cadmium (Cd), and mercury (Hg)], in four types of biological material in bones of the dog Canis lupus familiaris. The experiment was carried out on bones from the hip joints of dogs. The samples of cartilage, compact bone, spongy bone, and cartilage with adjacent compact bone came from 26 domestic dogs from northwestern Poland. Concentrations of Cu, Zn, Pb, and Cd were determined by ICP-AES (atomic absorption spectrophotometry) in inductively coupled argon plasma, using a Perkin-Elmer Optima 2000 DV. Determination of Hg concentration was performed by atomic absorption spectroscopy. In the examined bone material from the dog, the greatest concentrations (median) were observed for Zn and the lowest for Hg (98 mg Zn/kg and 0.0015 mg Hg/kg dw, respectively). In cartilage and spongy bone, metal concentrations could be arranged in the following descending order: Zn > Pb > Cu > Cd > Hg. In compact bone, the order was slightly different: Zn > Pb > Cd > Cu > Hg (from median 70 mg/kg dw to 0.002 mg/kg dw). The comparisons of metal concentrations between the examined bone materials showed distinct differences only in relation to Hg: between concentrations in spongy bone, compact bone, and in cartilage, being greater in cartilage than in compact bone, and lower again in spongy bone.

Nondestructive Determination of Cu Residue in Orange Peel by Laser Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Hu, Huiqin; Huang, Lin; Liu, Muhua; Chen, Tianbing; Yang, Ping; Yao, Mingyin

2015-08-01

Laser induced breakdown spectroscopy (LIBS) is an emerging tool with rapid, nondestructive, green characteristics in qualitative or quantitative analyses of composition in materials. But LIBS has its shortcomings in detect limit and sensitivity. In this work, heavy metal Cu in Gannan Navel Orange, which is one of famous fruits from Jiangxi of China, was analyzed. In view of LIBS's limit, it is difficult to determinate heavy metals in natural fruits. In this work, nine orange samples were pretreated in 50-500 μg/mL Cu solution, respectively. Another one orange sample was chosen as a control group without any pollution treatment. Previous researchers observed that the content of heavy metals is much higher in peel than in pulp. So, the content in pulp can be reflected by detecting peel. The real concentrations of Cu in peels were acquired by atomic absorption spectrophotometer (AAS). A calibration model of Cu I 324.7 and Cu I 327.4 was constructed between LIBS intensity and AAS concentration by six samples. The correlation coefficient of the two models is also 0.95. All of the samples were used to verify the accuracy of the model. The results show that the relative error (RE) between predicted and real concentration is less than 6.5%, and Cu I 324.7 line has smaller RE than Cu I 327.4. The analysis demonstrated that different characteristic lines decided different accuracy. The results prove the feasibility of detecting heavy metals in fruits by LIBS. But the results are limited in treated samples. The next work will focus on direct analysis of heavy metals in natural fruits without any pretreatment. This work is helpful to explore the distribution of heavy metals between pulp and peel. supported by National Natural Science Foundation of China (No. 31460419) and Major Project of Science and Technology of Jiangxi, China (No. 20143ACB21013)

Spectroscopic and Density Functional Theory Studies of the Blue–Copper Site in M121SeM and C112SeC Azurin: Cu–Se Versus Cu–S Bonding

PubMed Central

Sarangi, Ritimukta; Gorelsky, Serge I.; Basumallick, Lipika; Hwang, Hee Jung; Pratt, Russell C.; Stack, T. Daniel P.; Lu, Yi; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.

2009-01-01

S K-edge X-ray absorption, UV–vis absorption, magnetic circular dichroism (MCD), and resonance Raman spectroscopies are used to investigate the electronic structure differences among WT, M121SeM, and C112SeC Pseudomonas aeruginosa (P.a) azurin. A comparison of S K-edge XAS of WT and M121SeM azurin and a CuII–thioether model complex shows that the 38% S character in the ground state wave function of the blue–copper (BC) sites solely reflects the Cu–SCys bond. Resonance Raman (rR) data on WT and C112SeC azurin give direct evidence for the kinematic coupling between the Cu–SCys stretch and the cysteine deformation modes in WT azurin, which leads to multiple features in the rR spectrum of the BC site. The UV–vis absorption and MCD data on WT, M121SeM, and C112SeC give very similar C0/D0 ratios, indicating that the C-term MCD intensity mechanism involves Cu-centered spin–orbit coupling (SOC). The spectroscopic data combined with density functional theory (DFT) calculations indicate that SCys and SeCys have similar covalent interactions with Cu at their respective bond lengths of 2.1 and 2.3 Å. This reflects the similar electronegativites of S and Se in the thiolate/selenolate ligand fragment and explains the strong spectroscopic similarities between WT and C112SeC azurin. PMID:18314977

Synthesis of Ge-nanoparticles in organic solution

NASA Astrophysics Data System (ADS)

Pugsley, Andrew James

Much interest is focused on the synthesis of semiconductor particles from organic solution, in order to provide luminescent tracers for biological assays. However, group IV semiconductors have been largely neglected be cause of the lack of suitable nanoparticle formation reactions by solution-phase chemistries. A potentially useful new route to solution-based synthesis of nanocrystalline-Si,Ge involves the reaction between Zintl phases (NaSi, Mg 2Ge) that formally contain anionic semiconducting group species (Si-, Ge4-) and liquid phase SiCU, GeCU, etc. Luminescent nanoparticles formed by these reactions in organic solvents (e.g. diglyme) have been decribed in work from the Kauzlarich group at UC Davis (California, USA). The aim of this project has been to characterise the structural chemistry and luminescent properties of the products of the reaction, as well as following the course of the reaction in situ via synchrotron measurements. The product of the reaction has been characterised by TEM and x-ray absorption spectroscopy as well as other techniques. In order to analyse the x-ray absorption spectroscopy data, a number of model compounds have been studied, including the precursor material which was previously uncharacterised by this technique. An in situ reaction cell has been designed and built and used at a number of synchrotron beamlines to follow the course of the reaction. It has been found that the presence of even low concentrations of water can greatly affect the formation reaction, this is described herein.

Growth control, structure, chemical state, and photoresponse of CuO-CdS core-shell heterostructure nanowires.

PubMed

El Mel, A A; Buffière, M; Bouts, N; Gautron, E; Tessier, P Y; Henzler, K; Guttmann, P; Konstantinidis, S; Bittencourt, C; Snyders, R

2013-07-05

The growth of single-crystal CuO nanowires by thermal annealing of copper thin films in air is studied. We show that the density, length, and diameter of the nanowires can be controlled by tuning the morphology and structure of the copper thin films deposited by DC magnetron sputtering. After identifying the optimal conditions for the growth of CuO nanowires, chemical bath deposition is employed to coat the CuO nanowires with CdS in order to form p-n nanojunction arrays. As revealed by high-resolution TEM analysis, the thickness of the polycrystalline CdS shell increases when decreasing the diameter of the CuO core for a given time of CdS deposition. Near-edge x-ray absorption fine-structure spectroscopy combined with transmission x-ray microscopy allows the chemical analysis of isolated nanowires. The absence of modification in the spectra at the Cu L and O K edges after the deposition of CdS on the CuO nanowires indicates that neither Cd nor S diffuse into the CuO phase. We further demonstrate that the core-shell nanowires exhibit the I-V characteristic of a resistor instead of a diode. The electrical behavior of the device was found to be photosensitive, since increasing the incident light intensity induces an increase in the collected electrical current.

X-Ray absorption spectroscopy quantitative analysis of biomimetic copper(II) complexes with tridentate nitrogen ligands mimicking the tris(imidazole) array of protein centres.

PubMed

Borghi, Elena; Casella, Luigi

2010-02-21

In this study copper(ii) complexes with the tridentate nitrogen ligand bis[2-(1-methylbenzimidazol-2-yl)ethyl]amine (2-BB) are considered as model compounds for the Cu-tris(imidazole) array found in several copper proteins. 2-BB chelates copper(ii) forming two six-membered rings and the complexes contain methanol, nitrite, azide and water as ancillary ligands; both the coordination numbers and stereochemistries differ in these complexes. Their key structural features were investigated by using full multiple-scattering theoretical analysis of the copper K-edge X-ray absorption spectrum with the MXAN code. We showed that using cluster sizes large enough to include all atoms of the ligand, the analysis of the XANES region can give both a structural model of the metal centre and map the structure of the 2-BB complexes. Complex [Cu(2-BB)(N(3))](+) provided a critical test through the comparison of the XANES simulation results with crystallographic data, thus permitting the extension of the method to the complex [Cu(2-BB)(H(2)O)(n)](+) (n = 1 or 2), for which crystallographic data are not available but is expected to bear a five-coordinated Cu(3N)(2O) core (n = 2). The structural data of [Cu(2-BB)(MeOH)(ClO(4))](+) and [Cu(2-BB)(NO(2))](+), both with a Cu(3N)(2O) core but with a different stereochemistry, were used as the starting parameters for two independent simulations of the XANES region of the [Cu(2-BB)(H(2)O)(2)](+) cation. The two structural models generated by simulation converge towards a structure for the aqua-cation with a lower coordination number. New calculations, where four-coordinated Cu(3N)(O) cores were considered as the starting structures, validated that the structure of the aqua-complex in the powder state has a copper(ii) centre with a four-coordinated Cu(3N)(O) core and a molecular formula [Cu(2-BB)(H(2)O)](ClO(4)).(H(2)O). A water solvation molecule, presumed to be disordered from the simulations with the two Cu(3N)(2O) cores, is present. The successful treatment of this Cu-2-BB complex system allows the extension of the method to other biomimetic compounds when a structural characterization is lacking.

The effect of Se/Te ratio on transient absorption behavior and nonlinear absorption properties of CuIn0.7Ga0.3(Se1-xTex)2 (0 ≤ x ≤ 1) amorphous semiconductor thin films

NASA Astrophysics Data System (ADS)

Karatay, Ahmet; Küçüköz, Betül; Çankaya, Güven; Ates, Aytunc; Elmali, Ayhan

2017-11-01

The characterization of the CuInSe2 (CIS), CuInGaSe (CIGS) and CuGaSe2 (CGS) based semiconductor thin films are very important role for solar cell and various nonlinear optical applications. In this paper, the amorphous CuIn0.7Ga0.3(Se1-xTex)2 semiconductor thin films (0 ≤ x ≤ 1) were prepared with 60 nm thicknesses by using vacuum evaporation technique. The nonlinear absorption properties and ultrafast transient characteristics were investigated by using open aperture Z-scan and ultrafast pump-probe techniques. The energy bandgap values were calculated by using linear absorption spectra. The bandgap values are found to be varying from 0.67 eV to 1.25 eV for CuIn0.7Ga0.3Te2, CuIn0.7Ga0.3Se1.6Te0.4, CuIn0.7Ga0.3Se0.4Te1.6 and CuIn0.7Ga0.3Se2 thin films. The energy bandgap values decrease with increasing telluride (Te) doping ratio in mixed CuIn0.7Ga0.3(Se1-xTex)2 films. This affects nonlinear characteristics and ultrafast dynamics of amorphous thin films. Ultrafast pump-probe experiments indicated that decreasing of bandgap values with increasing the Te amount switches from the excited state absorption signals to ultrafast bleaching signals. Open aperture Z-scan experiments show that nonlinear absorption properties enhance with decreasing bandgaps values for 65 ps pulse duration at 1064 nm. Highest nonlinear absorption coefficient was found for CuIn0.7Ga0.3Te2 thin film due to having the smallest energy bandgap.

Complete transformation of ZnO and CuO nanoparticles in culture medium and lymphocyte cells during toxicity testing.

PubMed

Ivask, Angela; Scheckel, Kirk G; Kapruwan, Pankaj; Stone, Vicki; Yin, Hong; Voelcker, Nicolas H; Lombi, Enzo

2017-03-01

Here, we present evidence on complete transformation of ZnO and CuO nanoparticles, which are among the most heavily studied metal oxide particles, during 24 h in vitro toxicological testing with human T-lymphocytes. Synchrotron radiation-based X-ray absorption near edge structure (XANES) spectroscopy results revealed that Zn speciation profiles of 30 nm and 80 nm ZnO nanoparticles, and ZnSO 4 - exposed cells were almost identical with the prevailing species being Zn-cysteine. This suggests that ZnO nanoparticles are rapidly transformed during a standard in vitro toxicological assay, and are sequestered intracellularly, analogously to soluble Zn. Complete transformation of ZnO in the test conditions was further supported by almost identical Zn spectra in medium to which ZnO nanoparticles or ZnSO 4 was added. Likewise, Cu XANES spectra for CuO and CuSO 4 -exposed cells and cell culture media were similar. These results together with our observation on similar toxicological profiles of ZnO and soluble Zn, and CuO and soluble Cu, underline the importance of dissolution and subsequent transformation of ZnO and CuO nanoparticles during toxicological testing and provide evidence that the nano-specific effect of ZnO and CuO nanoparticles is negligible in this system. We strongly suggest to account for this aspect when interpreting the toxicological results of ZnO and CuO nanoparticles.

A porous Cu/LDPE composite for copper-containing intrauterine contraceptive devices.

PubMed

Zhang, Weiwei; Xia, Xianping; Qi, Cheng; Xie, Changsheng; Cai, Shuizhou

2012-02-01

To improve the rates of both cupric ion release and the utilization of copper in non-porous copper/low-density polyethylene (Cu/LDPE) composite, a porous Cu/LDPE composite is proposed and developed in the present work. Here 2,5-di-tert-butylhydroquinone was chosen as the porogen, ethyl acetate was chosen as the solvent for extraction, and the porous Cu/LDPE composite was obtained by using injection molding and the particulate leaching method. After any residual ethyl acetate remaining inside the porous Cu/LDPE composite had been removed by vacuum drying, the composite was characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry and absorption measurement. For comparison, a non-porous Cu/LDPE composite was also characterized in the same way. The results show that the porous structure was successfully introduced into the polymeric base of the non-porous Cu/LDPE composite, and the porous Cu/LDPE composite is a simple hybrid of copper particles and porous LDPE. The results also show that the introduction of a porous structure can improve the cupric ion release rate of the non-porous Cu/LDPE composite with a certain content of copper particles, indicating that the utilization rate of copper can be improved either the introduction of a porous structure, and that the porous Cu/LDPE composite is another promising material for copper-containing intrauterine devices. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis, characterization and effect of calcination temperature on phase transformation and photocatalytic activity of Cu,S-codoped TiO 2 nanoparticles

NASA Astrophysics Data System (ADS)

Hamadanian, M.; Reisi-Vanani, A.; Majedi, A.

2010-01-01

A novel copper and sulfur codoped TiO 2 photocatalyst was synthesized by modified sol-gel method using titanium(IV) isopropoxide, CuCl 2·2H 2O and thiourea as precursors. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy equipped with energy dispersive X-ray micro-analysis (SEM-EDX), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) analysis. The XRD results showed undoped and Cu,S-codoped TiO 2 nanoparticles only include anatase phase. Effect of calcination temperature showed rutile phase appears in 650 and 700 °C for undoped and 0.1% Cu,S-codoped TiO 2, respectively. The SEM analysis revealed the doping of Cu and S does not leave any change in morphology of the catalyst surface. The increase of copper doping enhanced "red-shift" in the UV-vis absorption spectra. The TEM images confirmed the dopants suppressed the growth of TiO 2 grains. The photocatalytic activity of samples was tested for degradation of methyl orange (MO) solutions. The results showed photocatalytic activity of the catalysts with 0.05% Cu,0.05% S and 0.1% Cu,0.05% S were higher than that of other catalysts under ultraviolet (UV) and visible irradiation, respectively. Because of synergetic effect of S and Cu, the Cu,S-codoped TiO 2 catalyst has higher activity than undoped and Cu or S doped TiO 2 catalysts.

Complete transformation of ZnO and CuO nanoparticles in ...

EPA Pesticide Factsheets

Here, we present evidence on complete transformation of ZnO and CuO nanoparticles, which are among the most heavily studied metal oxide particles, during 24 h in vitro toxicological testing with human T-lymphocytes. Synchrotron radiation-based X-ray absorption near edge structure (XANES) spectroscopy results revealed that Zn speciation profiles of 30 nm and 80 nm ZnO nanoparticles, and ZnSO4- exposed cells were almost identical with the prevailing species being Zn-cysteine. This suggests that ZnO nanoparticles are rapidly transformed during a standard in vitro toxicological assay, and are sequestered intracellularly, analogously to soluble Zn. Complete transformation of ZnO in the test conditions was further supported by almost identical Zn spectra in medium to which ZnO nanoparticles or ZnSO4 was added. Likewise, Cu XANES spectra for CuO and CuSO4-exposed cells and cell culture media were similar. These results together with our observation on similar toxicological profiles of ZnO and soluble Zn, and CuO and soluble Cu, underline the importance of dissolution and subsequent transformation of ZnO and CuO nanoparticles during toxicological testing and provide evidence that the nano-specific effect of ZnO and CuO nanoparticulates is negligible in this system. We strongly suggest to account for this aspect when interpreting the toxicological results of ZnO and CuO nanoparticles. Although a number of studies have discussed the transformation of nanoparticles during

Brain electrophysiology in Sprague-Dawley rats fed low copper diets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Penland, J.G.; Sawler, B.G.; Klevay, L.M.

1986-03-01

Electrical activity of the brain was assessed in 38 unanesthetized male rats fed a Cu deficient diet for c.100 days after weaning. Rats were supplemented with drinking solutions containing 0, 0.75, or 2 ..mu..g Cu/ml and 10 ..mu..g Zn/ml (as sulfate and acetate, respectively). Three weeks prior to recording, dural ball electrodes were placed bilaterally 1 mm anterior to the lambda and 4 mm lateral to the midline, with a midline reference 2 mm anterior to the bregma. Cu deficiency was verified by atomic absorption spectroscopy of plasma Cu (p < .0001). The electroencephalogram revealed dietary effects on both logmore » power and arcsin percent-total power in each of four frequency bands (1-3, 4-7, 8-12, 13-18 Hz). Low dietary Cu resulted in less log power and percent-total power in the lowest frequencies, and log power evidenced lateralized effects in the higher frequencies. Rats fed the diet most deficient in Cu had lower left and higher right hemisphere power than did rats fed the more adequate Cu diets. Percent-total power was higher in the mid-range frequencies in both hemispheres for rats fed the Cu deficient diets, compared to rats supplemented with the largest amount of Cu. The findings confirm a previous experiment (unpublished) and suggest that dietary Cu influences the electrical activity of the brain in a select (i.e., frequency and location specific) rather than undifferentiated manner.« less

CuTaS 3 : Intermetal d–d Transitions Enable High Solar Absorption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heo, Jaeseok; Yu, Liping; Altschul, Emmeline

To realize the fundamental limits of photovoltaic device efficiency, solar absorbers must exhibit strong absorption and abrupt absorption onsets. Ideally, onsets to maximum absorption (a > 105 cm-1) occur over a few tenths of an electronvolt. First-principles calculations predict CuTaS3 represents a potentially new class of materials with such absorption characteristics. Narrow metallic d bands in both the initial and final states present high joint densities of states and, therefore, strong absorption. Specifically, a mixture of metal d (Cu1+, d10) and S p characterizes states near the valence band maximum, and metal d (Ta5+, d0) dominates near the conduction bandmore » minimum. Optical absorption measurements on thin films confirm the abrupt onset to strong absorption a > 105 cm-1 at Eg + 0.4 eV (Eg = 1.0 eV). Theoretical CuTaS3 solar cell efficiency is predicted to be 28% for a 300 nm film based on the metric of spectroscopic limited maximum efficiency, which exceeds that of CuInSe2. This sulfide may offer new opportunities to discover and develop a new class of mixed d-element solar absorbers.« less

Thermal Annealing Effect on Poly(3-hexylthiophene): Fullerene:Copper-Phthalocyanine Ternary Photoactive Layer

PubMed Central

Derouiche, H.; Mohamed, A. B.

2013-01-01

We have fabricated poly(3-hexylthiophene) (P3HT)/copper phthalocyanine (CuPc)/fullerene (C60) ternary blend films. This photoactive layer is sandwiched between an indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT/PSS) photoanode and a bathocuproine (BCP)/aluminium photocathode. The thin films have been characterized by atomic force microscope (AFM) and ultraviolet/visible spectroscopy in order to study the influence of P3HT doping on the morphological and optical properties of the photoactive layer. We have also compared the I-V characteristics of three different organic solar cells: ITO/PEDOT:PSS/CuPc0.5:C600.5/BCP/Al and ITO/PEDOT:PSS/P3HT0.3:CuPc0.3:C600.4/BCP/Al with and without annealing. Both structures show good photovoltaic behaviour. Indeed, the incorporation of P3HT into CuPc:C60 thin film improves all the photovoltaic characteristics. We have also seen that thermal annealing significantly improves the optical absorption ability and stabilizes the organic solar cells making it more robust to chemical degradation. PMID:23766722

Thermal annealing effect on poly(3-hexylthiophene): fullerene:copper-phthalocyanine ternary photoactive layer.

PubMed

Derouiche, H; Mohamed, A B

2013-01-01

We have fabricated poly(3-hexylthiophene) (P3HT)/copper phthalocyanine (CuPc)/fullerene (C60) ternary blend films. This photoactive layer is sandwiched between an indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT/PSS) photoanode and a bathocuproine (BCP)/aluminium photocathode. The thin films have been characterized by atomic force microscope (AFM) and ultraviolet/visible spectroscopy in order to study the influence of P3HT doping on the morphological and optical properties of the photoactive layer. We have also compared the I-V characteristics of three different organic solar cells: ITO/PEDOT:PSS/CuPc₀.₅:C60₀.₅/BCP/Al and ITO/PEDOT:PSS/P3HT₀.₃:CuPc₀.₃:C60₀.₄/BCP/Al with and without annealing. Both structures show good photovoltaic behaviour. Indeed, the incorporation of P3HT into CuPc:C60 thin film improves all the photovoltaic characteristics. We have also seen that thermal annealing significantly improves the optical absorption ability and stabilizes the organic solar cells making it more robust to chemical degradation.

Effect of Ligand Exchange on the Photoluminescence Properties of Cu-Doped Zn-In-Se Quantum Dots

NASA Astrophysics Data System (ADS)

Dong, Xiaofei; Xu, Jianping; Yang, Hui; Zhang, Xiaosong; Mo, Zhaojun; Shi, Shaobo; Li, Lan; Yin, Shougen

2018-04-01

The surface-bound ligands of a semiconductor nanocrystal can affect its electron transition behavior. We investigate the photoluminescence (PL) properties of Cu-doped Zn-In-Se quantum dots (QDs) through the exchange of oleylamine with 6-mercaptohexanol (MCH). Fourier transform infrared and 1H nuclear magnetic resonance spectroscopies, and mass spectrometry reveal that the short-chain MCH molecules are bound to the QD surface. The emission peaks remain unchanged after ligand exchange, and the PL quantum yield is reduced from 49% to 38%. The effects of particle size and defect type on the change in PL behavior upon ligand substitution are excluded through high-resolution transmission electron microscopy, UV-Vis absorption, and PL spectroscopies. The origin of the decreased PL intensity is associated with increased ligand density and the stronger ligand electron-donating abilities of MCH-capped QDs that induce an increase in the nonradiative transition probability. A lower PL quenching transition temperature is observed for MCH-capped QDs and is associated with increasing electron-acoustic phonon coupling due to the lower melting temperature of MCH.

Spectroscopic determination of crystal-field levels in CeRh2Si2 and CeRu2Si2 and of the 4f0 contributions in CeM2Si2 (M=Cu, Ru, Rh, Pd, and Au)

NASA Astrophysics Data System (ADS)

Willers, T.; Adroja, D. T.; Rainford, B. D.; Hu, Z.; Hollmann, N.; Körner, P. O.; Chin, Y.-Y.; Schmitz, D.; Hsieh, H. H.; Lin, H.-J.; Chen, C. T.; Bauer, E. D.; Sarrao, J. L.; McClellan, K. J.; Byler, D.; Geibel, C.; Steglich, F.; Aoki, H.; Lejay, P.; Tanaka, A.; Tjeng, L. H.; Severing, A.

2012-01-01

We have determined the ground-state wave functions and crystal-field-level schemes of CeRh2Si2 and CeRu2Si2 using linear polarized soft x-ray-absorption spectroscopy (XAS) and inelastic neutron scattering. We find large crystal-field splittings and ground-state wave functions which are made of mainly Jz = |±5/2> with some amount of |∓3/2> in both the compounds. The 4f0 contribution to the ground state of several members of the CeM2Si2 family with M=(Cu, Ru, Rh, Pd, and Au) has been determined with XAS, and the comparison reveals a trend concerning the delocalization of the f electrons. Absolute numbers are extracted from scaling to results from hard x-ray photoelectron spectroscopy on CeRu2Si2 by Yano [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.77.035118 77, 035118 (2008)].

Investigation of the wavelength dependence of laser stratigraphy on Cu and Ni coatings using LIBS compared to a pure thermal ablation model

NASA Astrophysics Data System (ADS)

Paulis, Evgeniya; Pacher, Ulrich; Weimerskirch, Morris J. J.; Nagy, Tristan O.; Kautek, Wolfgang

2017-12-01

In this study, galvanic coatings of Cu and Ni, typically applied in industrial standard routines, were investigated. Ablation experiments were carried out using the first two harmonic wavelengths of a pulsed Nd:YAG laser and the resulting plasma spectra were analysed using a linear Pearson correlation method. For both wavelengths the absorption/ablation behaviour as well as laser-induced breakdown spectroscopy (LIBS) depth profiles were studied varying laser fluences between 4.3-17.2 J/cm^2 at 532 nm and 2.9-11.7 J/cm^2 at 1064 nm. The LIBS-stratigrams were compared with energy-dispersive X-ray spectroscopy of cross-sections. The ablation rates were calculated and compared to theoretical values originating from a thermal ablation model. Generally, higher ablation rates were obtained with 532 nm light for both materials. The light-plasma interaction is suggested as possible cause of the lower ablation rates in the infrared regime. Neither clear evidence of the pure thermal ablation, nor correlation with optical properties of investigated materials was obtained.

New crystal structures in hexagonal CuInS2 nanocrystals

NASA Astrophysics Data System (ADS)

Shen, Xiao; Hernández-Pagan, Emil A.; Zhou, Wu; Puzyrev, Yevgeniy S.; Idrobo, Juan C.; MacDonald, Janet E.; Pennycook, Stephen J.; Pantelides, Sokrates T.

2013-03-01

CuInS2 is one of the best candidate materials for solar energy harvesting. Its nanocrystals with a hexagonal lattice structure that is different from the bulk chalcopyrite phase have been synthesized by many groups. The structure of these CuInS2 nanocrystals has been previously identified as the wurtzite structure in which the copper and indium atoms randomly occupy the cation sites. Using first-principles total energy and electronic structure calculations based on density functional theory, UV-vis absorption spectroscopy, X-ray diffraction, and atomic resolution Z-contrast images obtained in an aberration-corrected scanning transmission electron microscope, we show that CuInS2 nanocrystals do not form random wurtzite structure. Instead, the CuInS2 nanocrystals consist of several wurtzite- related crystal structures with ordered cation sublattices, some of which are reported for the first time here. This work is supported by the NSF TN-SCORE (JEM), by NSF (WZ), by ORNL's Shared Research Equipment User Program (JCI) sponsored by DOE BES, by DOE BES Materials Sciences and Engineering Division (SJP, STP), and used resources of the National Energy Research Scientific Computing Center, supported by the DOE Office of Science under Contract No. DE-AC02-05CH11231.

Energy Dispersive XAFS: Characterization of Electronically Excited States of Copper(I) Complexes

PubMed Central

2013-01-01

Energy dispersive X-ray absorption spectroscopy (ED-XAS), in which the whole XAS spectrum is acquired simultaneously, has been applied to reduce the real-time for acquisition of spectra of photoinduced excited states by using a germanium microstrip detector gated around one X-ray bunch of the ESRF (100 ps). Cu K-edge XAS was used to investigate the MLCT states of [Cu(dmp)2]+ (dmp =2,9-dimethyl-1,10-phenanthroline) and [Cu(dbtmp)2]+ (dbtmp =2,9-di-n-butyl-3,4,7,8-tetramethyl-1,10-phenanthroline) with the excited states created by excitation at 450 nm (10 Hz). The decay of the longer lived complex with bulky ligands, was monitored for up to 100 ns. DFT calculations of the longer lived MLCT excited state of [Cu(dbp)2]+ (dbp =2,9-di-n-butyl-1,10-phenanthroline) with the bulkier diimine ligands, indicated that the excited state behaves as a Jahn–Teller distorted Cu(II) site, with the interligand dihedral angle changing from 83 to 60° as the tetrahedral coordination geometry flattens and a reduction in the Cu–N distance of 0.03 Å. PMID:23718738

Antibacterial and Antimycotic Activity of Cotton Fabrics, Impregnated with Silver and Binary Silver/Copper Nanoparticles

NASA Astrophysics Data System (ADS)

Eremenko, A. M.; Petrik, I. S.; Smirnova, N. P.; Rudenko, A. V.; Marikvas, Y. S.

2016-01-01

Effective method of obtaining of the bactericidal bandage materials by impregnation of cotton fabric by aqueous solutions of silver and copper salts followed by a certain regime of heat treatment is developed. The study of obtained materials by methods of optical spectroscopy, electron microscopy, and X-ray phase analysis showed the formation of crystalline silver nanoparticles (NPs) and bimetallic Ag/Cu composites with the corresponding surface plasmon resonance (SPR) bands in the absorption spectra. High antimicrobial and antimycotic properties of tissues with low concentrations of Ag and Ag/Cu nanoparticles (Ag/Cu NPs) (in the range 0.06-0.25 weight percent (wt%) for Ag and 0.015-0.13 wt% for Ag/Cu) is confirmed in experiments with a wide range of multidrug-resistant bacteria and fungi: Escherichia coli, Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, Candida albicans yeasts, and micromycetes . Textile materials with Ag NPs demonstrate high antibacterial activity, while fabrics doped with bimetallic composite Ag/Cu have pronounced antimycotic properties. Bactericidal and antifungal properties of the obtained materials do not change after a washing. Production of such materials is extremely fast, convenient, and cost-effective.

Decomposition of L a2 -xS rxCu O4 into several L a2O3 phases at elevated temperatures in ultrahigh vacuum inside a transmission electron microscope

NASA Astrophysics Data System (ADS)

Jeong, Jong Seok; Wu, Wangzhou; Topsakal, Mehmet; Yu, Guichuan; Sasagawa, Takao; Greven, Martin; Mkhoyan, K. Andre

2018-05-01

We report the decomposition of L a2 -xS rxCu O4 into L a2O3 and Cu nanoparticles in ultrahigh vacuum, observed by in situ heating experiments in a transmission electron microscope. The analysis of electron diffraction data reveals that the phase decomposition process starts at about 150 °C and is considerably expedited in the temperature range of 350 °C-450 °C. Two major resultant solid phases are identified as metallic Cu and L a2O3 by electron diffraction, simulation, and electron energy-loss spectroscopy (EELS) analyses. With the aid of calculations, L a2O3 phases are further identified to be derivatives of a fluorite structure—fluorite, pyrochlore, and (distorted) bixbyite—characterized by different oxygen-vacancy order. Additionally, the bulk plasmon energy and the fine structures of the O K and La M4 ,5 EELS edges are reported for these structures, along with simulated O K x-ray absorption near-edge structure. The resultant Cu nanoparticles and L a2O3 phases remain unchanged after cooling to room temperature.

Mapping of lead, magnesium and copper accumulation in plant tissues by laser-induced breakdown spectroscopy and laser-ablation inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Kaiser, J.; Galiová, M.; Novotný, K.; Červenka, R.; Reale, L.; Novotný, J.; Liška, M.; Samek, O.; Kanický, V.; Hrdlička, A.; Stejskal, K.; Adam, V.; Kizek, R.

2009-01-01

Laser-Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) were utilized for mapping the accumulation of Pb, Mg and Cu with a resolution up to 200 μm in a up to cm × cm area of sunflower ( Helianthus annuus L.) leaves. The results obtained by LIBS and LA-ICP-MS are compared with the outcomes from Atomic Absorption Spectrometry (AAS) and Thin-Layer Chromatography (TLC). It is shown that laser-ablation based analytical methods can substitute or supplement these techniques mainly in the cases when a fast multi-elemental mapping of a large sample area is needed.

Mixed polyanion glass cathodes: Glass-state conversion reactions

DOE PAGES

Kercher, Andrew K.; Kolopus, James A.; Carroll, Kyler; ...

2015-11-10

Mixed polyanion (MP) glasses can undergo glass-state conversion (GSC) reactions to provide an alternate class of high-capacity cathode materials. GSC reactions have been demonstrated in phosphate/vanadate glasses with Ag, Co, Cu, Fe, and Ni cations. These MP glasses provided high capacity and good high power performance, but suffer from moderate voltages, large voltage hysteresis, and significant capacity fade with cycling. Details of the GSC reaction have been revealed by x-ray absorption spectroscopy, electron microscopy, and energy dispersive x-ray spectroscopy of ex situ cathodes at key states of charge. Using the Open Quantum Materials Database (OQMD), a computational thermodynamic model hasmore » been developed to predict the near-equilibrium voltages of glass-state conversion reactions in MP glasses.« less

Synthesis and Spectroscopic Evaluation of Two Novel Glycosylated Zinc(II)-Phthalocyanines.

PubMed

Bächle, Felix; Hanack, Michael; Ziegler, Thomas

2015-10-09

In continuation of our work on glycoconjugated phthalocyanines, two new water soluble, non-ionic zinc(II) phthalocyanines have been prepared and fully characterized by means of ¹H-NMR, 13C-NMR, MALDI-TOF, ESI-TOF, UV-Vis spectroscopy, emission spectroscopy and fluorescence lifetime measurements. The carbohydrate-containing phthalonitrile precursors were synthesized through a copper-catalyzed azide-alkyne cycloaddition (CuAAC). The 2-methoxyethoxymethyl protecting group (MEM) was used to protect the carbohydrate moieties. It resisted the harsh basic cyclotetramerization conditions and could be easily cleaved under mild acidic conditions. The glycoconjugated zinc(II) phthalocyanines described here have molar extinction coefficents εmax>10⁵ m(-1) cm(-1) and absorption maxima λ>680 nm, which make them attractive photosensitizers for photo-dynamic therapy.

Luminescence Studies of the Ligand Exchange Between Two Phenanthroline Complexes and Bovine Serum Albumin

NASA Astrophysics Data System (ADS)

Lin, H.-B.; Shen, Q.-H.

2017-03-01

The interactions between bovine serum albumin (BSA) and two Cu(II) phenanthroline complexes were studied by fluorescence and UV-visible absorption spectroscopy. The obtained results confirm that the phen ligand (phen = 1,10-phenanthroline) is dissociated from the two complexes and moves into the hydrophobic cavity of BSA and that the M-L complexes (M = Co2+, Cu2+; L = Hlact, imda; Hlact = lactic acid, H2imda = iminodiacetic acid) coordinate with the amino acids on the surface of the peptide in the solution. This mode of action significantly inhibits the denaturation of BSA. The calculated distance between the BSA and the two complexes suggests that the energy transfer from the excited state of BSA to a complex occurs with high efficiency.

Refractive indices of layers and optical simulations of Cu(In,Ga)Se2 solar cells

PubMed Central

Avancini, Enrico; Losio, Paolo A.; Figi, Renato; Schreiner, Claudia; Bürki, Melanie; Bourgeois, Emilie; Remes, Zdenek; Nesladek, Milos; Tiwari, Ayodhya N.

2018-01-01

Abstract Cu(In,Ga)Se2 based solar cells have reached efficiencies close to 23%. Further knowledge-driven improvements require accurate determination of the material properties. Here, we present refractive indices for all layers in Cu(In,Ga)Se2 solar cells with high efficiency. The optical bandgap of Cu(In,Ga)Se2 does not depend on the Cu content in the explored composition range, while the absorption coefficient value is primarily determined by the Cu content. An expression for the absorption spectrum is proposed, with Ga and Cu compositions as parameters. This set of parameters allows accurate device simulations to understand remaining absorption and carrier collection losses and develop strategies to improve performances. PMID:29785230

Research on disposal of copper(II)-containing wastewater by secondary strontium residue

NASA Astrophysics Data System (ADS)

Qing, Duowen; Xu, Longjun; Cui, Caixi

2018-01-01

Secondary strontium residue (SSR) was used as absorbent to remove Cu2+ in solution and the effects of experimental conditions on absorption of Cu2+ were investigated. The results showed that the absorption process reached balance in around 40 min. The absorption capacity achieved the maximum when PH value reached 6, and the maximum adsorption of Cu2+-containing wastewater by secondary strontium residue was 5.46 mg/g. Removal ratio of Cu2+ was in relation to initial concentration of Cu2+ in solution. Adsorptive process tallied with Langmuir Isothermal adsorption model.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chuang, Yu-Chun; Sheu, Chou-Fu; Lee, Gene-Hsiang

High-resolution X-ray diffraction experiments and atom-specific X-ray absorption experiments are applied to investigate a series of square planar complexes with the non-innocent ligand of maleonitriledithiolate (mnt), [S 2C 2(CN) 2] z-, containingM—S bonds. Four complexes of (PyH) z[M(mnt) 2] z-, whereM= Ni or Cu,z= 2 or 1 and PyH += C 5NH 6 +, were studied in order to clarify whether such one-electron oxidation–reduction, [M(mnt) 2] 2-/[M(mnt) 2] 1-, is taking place at the metal or the ligand site. Combining the techniques of metalK-,L-edge and SK-edge X-ray absorption spectroscopy with high-resolution X-ray charge density studies, it is unambiguously demonstrated thatmore » the electron redox reaction is ligand based and metal based for Ni and Cu pairs, respectively. The bonding characters in terms of topological properties associated with the bond critical points are compared between the oxidized form [ML] -and the reduced form [ML] 2-. In the case of Ni complexes, the formal oxidation state of Ni remains as Ni 2+and each mnt ligand carries a 2- charge in [Ni(mnt) 2] 2-, but only one of the ligands is formally oxidized in [Ni(mnt) 2] 1-. In contrast, in the case of Cu complexes, the mnt remains as 2- in both complexes, but the formal oxidation states of the metal are Cu 2+and Cu 3+. Bond characterizations andd-orbital populations will be presented. The complementary results of XAS, XRD and DFT calculations will be discussed. The conclusion on the redox reactions in these complexes can be firmly established.« less

In Situ Distribution and Speciation of Toxic Copper, Nickel, and Zinc in Hydrated Roots of Cowpea1[W][OA

PubMed Central

Kopittke, Peter M.; Menzies, Neal W.; de Jonge, Martin D.; McKenna, Brigid A.; Donner, Erica; Webb, Richard I.; Paterson, David J.; Howard, Daryl L.; Ryan, Chris G.; Glover, Chris J.; Scheckel, Kirk G.; Lombi, Enzo

2011-01-01

The phytotoxicity of trace metals is of global concern due to contamination of the landscape by human activities. Using synchrotron-based x-ray fluorescence microscopy and x-ray absorption spectroscopy, the distribution and speciation of copper (Cu), nickel (Ni), and zinc (Zn) was examined in situ using hydrated roots of cowpea (Vigna unguiculata) exposed to 1.5 μm Cu, 5 μm Ni, or 40 μm Zn for 1 to 24 h. After 24 h of exposure, most Cu was bound to polygalacturonic acid of the rhizodermis and outer cortex, suggesting that binding of Cu to walls of cells in the rhizodermis possibly contributes to the toxic effects of Cu. When exposed to Zn, cortical concentrations remained comparatively low with much of the Zn accumulating in the meristematic region and moving into the stele; approximately 60% to 85% of the total Zn stored as Zn phytate within 3 h of exposure. While Ni concentrations were high in both the cortex and meristem, concentrations in the stele were comparatively low. To our knowledge, this is the first report of the in situ distribution and speciation of Cu, Ni, and Zn in hydrated (and fresh) plant tissues, providing valuable information on the potential mechanisms by which they are toxic. PMID:21525332

A new high selective and sensitive turn-on fluorescent and ratiometric absorption chemosensor for Cu2+ based on benzimidazole in aqueous solution and its application in live cell.

PubMed

Bing, Qijing; Wang, Lin; Li, Donglin; Wang, Guang

2018-09-05

A new benzimidazole base turn-on fluorescent and ratiometric absorption chemosensor (L) bearing bidentate ligand for detection of Cu 2+ was designed and synthesized. Fluorescence and UV-vis spectra studies demonstrated that L can detect Cu 2+ ions in aqueous solution using fluorescence enhancement and ratiometric absorption sensing over a wide pH range. Both fluorescent and ratiometric absorption sensing of L for Cu 2+ possessed high selectivity and sensitivity over other competitive metal ions and had low detection limit. Job's plot, mass spectra and DFT calculation indicated the sensing mechanism is the complex formation between L and Cu 2+ with 1:2 stoichiometry. Fluorescence images of HepG2 in the absence and presence of Cu 2+ displayed L had cell permeability and detection ability for Cu 2+ in live cells. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of biologically synthesized copper oxide nanoparticles on metabolism and antioxidant activity to the crop plants Solanum lycopersicum and Brassica oleracea var. botrytis.

PubMed

Singh, Ajey; Singh, N B; Hussain, Imtiyaz; Singh, Himani

2017-11-20

Study on the ecological effect of metal oxide nanomaterials (NMs) has quickly amplified over the precedent years because it is assumed that these NMs will sooner or later be released into the environment. The present study deals with biologically oriented process for the green synthesis of copper oxide nanoparticles (CuO NPs) by using Morus alba leaf extract as reducing agent. Powder X-ray diffraction (XRD) and transmission electron microscope (TEM) analysis revealed the monoclinic phase and 20-40nm size respectively. The presence of reducing and capping agents revealed by Fourier transform infrared (FTIR) spectroscopy. The seedlings of Brassica oleracea var. botrytis and Solanum lycopersicum were exposed to 10, 50, 100, and 500mgL -1 concentrations of CuO NPs in the sand medium. Bioaccumulation of Cu was also investigated by atomic absorption spectroscopy (AAS). Plant exposure to 100 and 500mgL -1 of CuO NPs has resulted in significant reduction of total chlorophyll and sugar content in the two test plants while 10mgL -1 of NPs slightly increased the pigment and sugar content in tomato plants only. Augmentation of lipid peroxidation, electrolyte leakage, and antioxidant enzyme activity was observed in a dose dependent manner upon plants exposure to CuO NPs. Deposition of lignin in roots of both plants treated with the highest concentration of CuO NPs was observed. Histochemical analysis of leaves of treated plant with nitroblue tetrazolium and 3 ' 3 ' diaminobenzidine showed a concentration dependent increase in superoxide and hydrogen peroxide formation in leaves. The green synthesis of CuO NPs was carried out by using Morus alba leaf extract. Accumulation of NPs more actively by tomato plants as compared to cauliflower was possibly due to the difference in root morphology. The histochemical visualization highlights the spatial organization of oxidant biochemistry occurring in response to metal stress. Copyright © 2017 Elsevier B.V. All rights reserved.

Green synthesis and characterization of cuprous oxide nanoparticles in presence of a bio-surfactant

NASA Astrophysics Data System (ADS)

Behera, M.; Giri, G.

2014-12-01

Herein, we report a facile green synthesis of Cu2O nanoparticles (NPs) using copper sulfate as precursor salt and hydrazine hydrate as reducing agent in presence of bio-surfactant (i.e. leaves extract of arka — a perennial shrub) at 60 to 70 °C in an aqueous medium. A broad band centered at 460 nm in absorption spectrum reveals the formation of surfactant stabilized Cu2O NPs. X-ray diffraction pattern of the surfactant stabilized NPs suggests the formation of only Cu2O phase in assistance of a bio-surfactant with the crystallite size of ˜8 nm. A negative zeta potential of -12 mV at 8.0 pH in surfactant stabilized Cu2O NPs hints non-bonding electron transfer from O-atom of saponin to the surface of NP. Red-shift in the vibrational band (Cu-O stretching) of Cu2O from 637 cm-1 to 640 cm-1 in presence of bio-surfactant suggests an interfacial interaction between NPs and O-atoms of -OH groups of saponin present in the plant (i.e. Calotropis gigantean) extract. From X-ray photoelectron spectroscopy spectra, a decrease in binding energy of both 2p3/2 and 2p1/2 bands in Cu2O with saponin molecules as compared to bulk Cu atom reveals a charge transfer interaction between NP and saponin surfactant molecules. Transmission electron microscopy images show crystalline nature of Cu2O NPs with an fcc lattice.

Efficient degradation of Methylene Blue dye over highly reactive Cu doped strontium titanate (SrTiO3) nanoparticles photocatalyst under visible light.

PubMed

Rahman, Qazi Inamur; Ahmad, Musheer; Misra, Sunil Kumar; Lohani, Minaxi

2012-09-01

Visible light induced photocatalysts of Cu doped SrTiO3 (Cu/SrTiO3) nanoparticles with the size -60-75 nm were prepared via facile sol-gel method. The morphological, optical, crystalline properties and compositions of synthesized Cu/SrTiO3 nanoparticles were thoroughly characterized by field emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (XRD), ultra violet-visible spectroscopy (UV-Vis) and energy dispersive X-ray (EDX). A significant red shift in the UV-diffused reflectance spectrum was observed and the absorption edge shifted to visible region by the Cu doping. Surprisingly, the band gap of SrTiO3 was changed from 3.2 eV drop to 2.96 eV. The photocatalytic activity of the synthesized Cu/SrTiO3 nanoparticles was demonstrated for the degradation of Methylene Blue dye under visible light irradiation. The formation of new acceptor region in Cu/SrTiO3 was responsible for high photocatalytic activity of Cu/SrTiO3 nanoparticles. The results showed that the Methylene Blue dye was degraded by -66% within time span of 2 h over the Cu/SrTiO3 nanoparticles. This dye degradation reaction followed the Langmuir-Hinshelwood kinetics and also exhibited first order reaction rate. The calculated rate constant for the degradation reaction following first order kinetics was k = 0.0016 min(-1).

Synthesis and characterization of structural, morphological and photosensor properties of Cu0.1Zn0.9S thin film prepared by a facile chemical method

NASA Astrophysics Data System (ADS)

Gubari, Ghamdan M. M.; Ibrahim Mohammed S., M.; Huse, Nanasaheb P.; Dive, Avinash S.; Sharma, Ramphal

2018-05-01

The Cu0.1Zn0.9S thin film was grown by facile chemical bath deposition (CBD) method on glass substrates at 60°C. The structural, morphological, photosensor properties of the as-grown thin film has been investigated. The structural and phase confirmation of the as-grown thin film was carried out by X-ray diffraction (XRD) technique and Raman spectroscopy. The FE-SEM images showed that the thin films are well covered with material on an entire glass substrate. From the optical absorption spectrum, the direct band gap energy for the Cu0.1Zn0.9S thin film was found to be ˜3.16 eV at room temperature. The electrical properties were measured at room temperature in the voltage range ±2.5 V, showed a drastic enhancement in current under light illumination with the highest photosensitivity of ˜72 % for 260 W.

Deposition and characterization of spray pyrolysed p-type Cu2SnS3 thin film for potential absorber layer of solar cell

NASA Astrophysics Data System (ADS)

Thiruvenkadam, S.; Sakthi, P.; Prabhakaran, S.; Chakravarty, Sujay; Ganesan, V.; Rajesh, A. Leo

2018-06-01

Thin film of ternary Cu2SnS3 (CTS), a potential absorber layer for solar cells was successfully deposited by chemical spray pyrolysis technique. The GIXRD pattern revealed that the film having tetragonal Cu2SnS3 phase with the preferential orientation along (112), (200), (220) and (312) plane and it is further confirmed using Raman spectroscopy by the existence of Raman peak at 320 cm-1. Atomic Force Microscopy (AFM) was used to estimate the surface roughness of 28.8 nm. The absorption coefficient was found to be greater than the order of 105 cm-1 and bandgap of 1.70 eV. Hall effect measurement indicates the p type nature of the film with a hole concentration of 1.03 × 1016cm-3 and a hall mobility of 404 cm2/V. The properties of CTS thin film confirmed suitable to be a potential absorber layer material for photovoltaic applications.

Speciation of copper diffused in a bi-porous molecular sieve

NASA Astrophysics Data System (ADS)

Huang, C.-H.; Paul Wang, H.; Wei, Y.-L.; Chang, J.-E.

2010-07-01

To better understand diffusion of copper in the micro- and mesopores, speciation of copper in a bi-porous molecular sieve (BPMS) possessing inter-connecting 3-D micropores (0.50-0.55 nm) and 2-D mesopores (4.1 nm) has been studied by X-ray absorption near edge structure (XANES) spectroscopy. It is found that about 77% (16% of CuO nanoparticles and 61% of CuO clusters) and 23% (CuO ads) of copper can be diffused into the meso- and micropores, respectively, in the BPMS. At least two diffusion steps in the BPMS may be involved: (i) free diffusion of copper in the mesopores and (ii) diffusion-controlled copper migrating into the micropores of the BPMS. The XANES data also indicate that diffusion rate of copper in the BPMS (4.68×10 -5 g/s) is greater than that in the ZSM-5 (1.11×10 -6 g/s) or MCM-41 (1.17×10 -5 g/s).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Yu; Yamani, Zahra; Cao, Chongde

Iron-based superconductivity develops near an antiferromagnetic order and out of a bad-metal normal state, which has been interpreted as originating from a proximate Mott transition. Whether an actual Mott insulator can be realized in the phase diagram of the iron pnictides remains an open question. Here we use transport, transmission electron microscopy, X-ray absorption spectroscopy, resonant inelastic X-ray scattering and neutron scattering to demonstrate that NaFe 1-xCu xAs near x≈0.5 exhibits real space Fe and Cu ordering, and are antiferromagnetic insulators with the insulating behaviour persisting above the Néel temperature, indicative of a Mott insulator. On decreasing x from 0.5,more » the antiferromagnetic-ordered moment continuously decreases, yielding to superconductivity ~x=0.05. Our discovery of a Mott-insulating state in NaFe 1-xCu xAs thus makes it the only known Fe-based material, in which superconductivity can be smoothly connected to the Mott-insulating state, highlighting the important role of electron correlations in the high-T c superconductivity.« less

The Copper Active Site of CBM33 Polysaccharide Oxygenases

PubMed Central

2013-01-01

The capacity of metal-dependent fungal and bacterial polysaccharide oxygenases, termed GH61 and CBM33, respectively, to potentiate the enzymatic degradation of cellulose opens new possibilities for the conversion of recalcitrant biomass to biofuels. GH61s have already been shown to be unique metalloenzymes containing an active site with a mononuclear copper ion coordinated by two histidines, one of which is an unusual τ-N-methylated N-terminal histidine. We now report the structural and spectroscopic characterization of the corresponding copper CBM33 enzymes. CBM33 binds copper with high affinity at a mononuclear site, significantly stabilizing the enzyme. X-band EPR spectroscopy of Cu(II)-CBM33 shows a mononuclear type 2 copper site with the copper ion in a distorted axial coordination sphere, into which azide will coordinate as evidenced by the concomitant formation of a new absorption band in the UV/vis spectrum at 390 nm. The enzyme’s three-dimensional structure contains copper, which has been photoreduced to Cu(I) by the incident X-rays, confirmed by X-ray absorption/fluorescence studies of both aqueous solution and intact crystals of Cu-CBM33. The single copper(I) ion is ligated in a T-shaped configuration by three nitrogen atoms from two histidine side chains and the amino terminus, similar to the endogenous copper coordination geometry found in fungal GH61. PMID:23540833

Femtosecond Laser Fabricated Ag@Au and Cu@Au Alloy Nanoparticles for Surface Enhaned Raman Spectrosocpy Based Trace Explosives Detection

NASA Astrophysics Data System (ADS)

Sree Satya Bharati, Moram; Byram, Chandu; Soma, Venugopal R.

2018-03-01

Herein we present results from our detailed studies on the fabrication of Ag@Au and Cu@Au alloy nanoparticles (NPs) using the femtosecond laser ablation in liquid technique. The NPs were obtained by ablating the pure Ag, Cu targets (bulk) in HAuCl4 (5 mM) solution. The absorption properties of the obtained NPs colloids were characterized using UV-Visible absorption spectrometer and their size, shape, and crystallinity were investigated using the XRD, FESEM and TEM techniques. The fabricated NPs were utilized for sensing of explosive molecules such as 2, 4, 6-trinitrophenol (PA), 2, 4-dinitrotoluene (DNT) and a common dye methylene blue (MB) using the surface enhanced Raman spectroscopy (SERS) technique. The detection limit in terms of weight was as low as few nano-grams in the case of nitroaromatic explosive compounds (PA, DNT) and few picograms in the case of a common dye molecule (MB). Typical enhancement factors achieved were estimated to be 104, 105 and 107, respectively, for PA, DNT, and MB. The significance of the present work lies in exploring the performance of the prepared NPs being used as SERS substrates for explosives detection using a portable Raman instrument. Such capability enables one to carry the spectrometer to the point of interest in the field and evaluate any hazardous samples within a short period of time.

Estimation of the molar absorption coefficient of copper salicylate within the spectral range 300-350 nm

NASA Astrophysics Data System (ADS)

Lavrik, N. L.; Mulloev, N. U.

2017-12-01

Additional absorption was detected in absorption spectra within the range 300-350 nm after addition of copper sulfate CuSO4(aq) to a solution of sodium salicylate NaНSal (рН = 7.8). The additional maximum absorption was observed at 320 nm. Assuming that the additional absorption depends on the formation of copper salicylate CuSal, the molar absorption coefficient εCuSal of this complex was determined to be (3.8 ± 0.02) · 103 М- 1 сm- 1. This value is almost equal to that of monoanion HSal-, εHSal - = (3.6 ± 0.04) · 103 М- 1 сm- 1, and is 2.5 times as much as εFe3 + HSal - = (1.55 ± 0.05) · 103 М- 1 сm- 1 for iron salicylate. The difference in εCuSal and εFe3 + HSal - is due to the difference in the initial electron states of Cu2 + and Fe3 + ions that have the d9 and d5 configurations, respectively.

Trends in reactivity of electrodeposited 3d transition metals on gold revealed by operando soft x-ray absorption spectroscopy during water splitting

NASA Astrophysics Data System (ADS)

Velasco-Vélez, J. J.; Jones, Travis E.; Pfeifer, Verena; Dong, Chung-Li; Chen, Yu-Xun; Chen, Chieh-Ming; Chen, Hsin-Yu; Lu, Ying-Rui; Chen, Jin-Ming; Schlögl, R.; Knop-Gericke, A.; Chuang, C.-H.

2017-01-01

We activated gold electrodes for their use as electrocatalyst for water splitting by electrodepositing Cu, Ni and Co. A combination of operando x-ray absorption spectroscopy and potentiometric control under aqueous conditions revealed the trends in reactivity yielded by these electrodes, which are directly associated with the cross- and overpotentials as well as the occupancy of the 3d orbitals. It was found that under anodic polarization the materials electrodeposited on gold suffer from a lack of stability, while under cathodic polarization they exhibit stable behavior. The observed activity is strongly related to the lack of stability shown by these composites under anodic polarization revealing a dynamic process ruled by corrosion. By operando x-ray absorption, we established that the overall enhancement of the activity for the oxygen evolution reaction is directly attributable to the cross-potential and corrosion process of the electrodeposited materials. It is associated with the high potential deposition, which is the origin of the incipient oxidation-corrosion resistance of the lattice. We conclude that the observed trends in the total current are directly associated with the loss of oxygen in the metal-oxide lattice and the subsequent dissolution of metallic ions in the electrolyte under anodic polarization.

Selective synthesis and redox sequence of a heterobimetallic nickel/copper complex of the noninnocent Siamese-twin porphyrin.

PubMed

Blusch, Lina K; Mitevski, Oliver; Martin-Diaconescu, Vlad; Pröpper, Kevin; DeBeer, Serena; Dechert, Sebastian; Meyer, Franc

2014-08-04

The Siamese-twin porphyrin (1H4) is a redox noninnocent pyrazole-expanded porphyrin with two equivalent dibasic {N4} binding sites. It is now shown that its selective monometalation can be achieved to give the nickel(II) complex 1H2Ni with the second {N4} site devoid of a metal ion. This intermediate is then cleanly converted to 1Ni2 and to the first heterobimetallic Siamese-twin porphyrin 1CuNi. Structural characterization of 1H2Ni shows that it has the same helical structure previously seen for 1Cu2, 1Ni2, and free base 1H6(2+). Titration experiments suggest that the metal-devoid pocket of 1H2Ni can accommodate two additional protons, giving [1H4Ni](2+). Both bimetallic complexes 1Ni2 and 1CuNi feature rich redox chemistry, similar to the recently reported 1Cu2, including two chemically reversible oxidations at moderate potentials between -0.3 and +0.5 V (vs Cp2Fe/Cp2Fe(+)). The locus of these oxidations, in singly oxidized [1Ni2](+) and [1CuNi](+) as well as twice oxidized [1CuNi](2+), has been experimentally derived from comparison of the electrochemical properties of the complete series of complexes 1Cu2, 1Ni2, and 1CuNi, and from electron paramagnetic resonance (EPR) spectroscopy and X-ray absorption spectroscopy (XAS) (Ni and Cu K edges). All redox events are largely ligand-based, and in heterobimetallic 1CuNi, the first oxidation takes place within its Cu-subunit, while the second oxidation then occurs in its Ni-subunit. Adding pyridine to solutions of [1Ni2](+) and [1CuNi](2+) cleanly converts them to metal-oxidized redox isomers with axial EPR spectra typical for Ni(III) having significant dz(2)(1) character, reflecting close similarity with nickel complexes of common porphyrins. The possibility of selectively synthesizing heterobimetallic complexes 1MNi from a symmetric binucleating ligand scaffold, with the unusual situation of three distinct contiguous redox sites (M, Ni, and the porphyrin-like ligand), further expands the Siamese-twin porphyrin's potential to serve as an adjustable platform for multielectron redox processes in chemical catalysis and in electronic applications.

Synthesis, Structure, and Characterization of Cu4S10(4-methylpyridine)4

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Richman, Robert M.; Duraj, Stan A.; Andras, Maria T.; Moore, Hall L.; Sabat, Michal; Eckles, William E.; Martuch, Robert A.

1996-01-01

The title compound, Cu4S10(4-methylpyridine)(sub 4) (dot) 4-methylpyridine was prepared by three different reactions: the oxidation of copper powder by sulfur and the reaction of copper (I) sulfide (or CuBr (dot) SMe2) with excess sulfur, both in the coordinating solvent, 4-methylpyridine. Red crystals of the compound obtained by layering with hexanes were subjected to single crystal X-ray diffraction. The structure was refined to R = 0.026 and R(sub w) = 0.036 in a space group P1bar (No. 2), with Z = 2, a = 13.983 (2) A, b = 15.384 (2) A, c = 9.660 (1) A, alpha = 93.87 (1)deg., beta = 93.38 (1)deg., gamma = 99.78 (1)deg., V = 2037.9 (9) A(exp 3). The compound has approximate S(sub 4) symmetry and consists of two pentasulfide chains linking four Cu(I) ions, each with a corrdinating 2-methylpyridine. The infrared spectrum was dominated by absorption due to coordinated 4-methylpyridine with several low-energy peaks attributable to S-S stretches, which were also observed by Raman spectroscopy. A featureless electronic absorption spectrum yielded a single peak in the near ultraviolet upon computer enhancement (lambda = 334 nm, epsilon = 10,000), most likely an intraligand transition. Cyclic voltammetry indicates that the polysulfide complex undergoes irrversible oxidation and reduction at +0.04 and -0.34 V vs. SCE, respectively, at 298 K in 4-methylpyridine when swept at 20 mV/sec. The electrochemical behavior was unvaried even at sweep rates as high as 100 V/sec.

Ultrafast carrier dynamics and third-order nonlinear optical properties of AgInS2/ZnS nanocrystals

NASA Astrophysics Data System (ADS)

Yu, Kuai; Yang, Yang; Wang, Junzhong; Tang, Xiaosheng; Xu, Qing-Hua; Wang, Guo Ping

2018-06-01

Broad photoluminescence (PL) emission, a large Stokes shift and extremely long-lived radiative lifetimes are the characteristics of ternary I–III–VI semiconductor nanocrystals (NCs), such as CuInS2 and AgInS2. However, the lack of understanding regarding the intriguing PL mechanisms and photo-carrier dynamics limits their further applications. Here, AgInS2 and AgInS2/ZnS NCs were chemically synthesized and their carrier dynamics were studied by time-resolved PL spectroscopy. The results demonstrated that the surface defect state, which contributed dominantly to the non-radiative decay processes, was effectively passivated through ZnS alloying. Femtosecond transient absorption spectroscopy was also used to investigate the carrier dynamics, revealing the electron storage at the surface state and donor state. Furthermore, the two photon absorption properties of AgInS2 and AgInS2/ZnS NCs were measured using an open-aperture Z-scan technique. The improved third-order nonlinear susceptibility {χ }(3) of AgInS2 through ZnS alloying demonstrates potential application in two photon PL biological imaging.

Fluorescence XAS using Ge PAD: Application to High-Temperature Superconducting Thin Film Single Crystals

NASA Astrophysics Data System (ADS)

Oyanagi, H.; Tsukada, A.; Naito, M.; Saini, N. L.; Zhang, C.

2007-02-01

A Ge pixel array detector (PAD) with 100 segments was used in fluorescence x-ray absorption spectroscopy (XAS) study, probing local structure of high temperature superconducting thin film single crystals. Independent monitoring of individual pixel outputs allows real-time inspection of interference of substrates which has long been a major source of systematic error. By optimizing grazing-incidence angle and azimuthal orientation, smooth extended x-ray absorption fine structure (EXAFS) oscillations were obtained, demonstrating that strain effects can be studied using high-quality data for thin film single crystals grown by molecular beam epitaxy (MBE). The results of (La,Sr)2CuO4 thin film single crystals under strain are related to the strain dependence of the critical temperature of superconductivity.

Ultraviolet optical absorptions of semiconducting copper phosphate glasses

NASA Technical Reports Server (NTRS)

Bae, Byeong-Soo; Weinberg, Michael C.

1993-01-01

Results are presented of a quantitative investigation of the change in UV optical absorption in semiconducting copper phosphate glasses with batch compositions of 40, 50, and 55 percent CuO, as a function of the Cu(2+)/Cu(total) ratio in the glasses for each glass composition. It was found that optical energy gap, E(opt), of copper phosphate glass is a function of both glass composition and Cu(2+)/Cu(total) ratio in the glass. E(opt) increases as the CuO content for fixed Cu(2+)/Cu(total) ratio and the Cu(2+)/Cu(total) ratio for fixed glass composition are reduced.

Excited state electron and energy relays in supramolecular dinuclear complexes revealed by ultrafast optical and X-ray transient absorption spectroscopy† †Electronic supplementary information (ESI) available: Synthesis schemes, experimental methods, NMR spectra, X-ray crystallographic information, emission spectra, cyclic voltammetry, electronic structure calculations, data analysis and numerical methods, and other additional figures. CCDC 1561879. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04055e

PubMed Central

Kohler, Lars; Hadt, Ryan G.; Zhang, Xiaoyi; Liu, Cunming

2017-01-01

The kinetics of photoinduced electron and energy transfer in a family of tetrapyridophenazine-bridged heteroleptic homo- and heterodinuclear copper(i) bis(phenanthroline)/ruthenium(ii) polypyridyl complexes were studied using ultrafast optical and multi-edge X-ray transient absorption spectroscopies. This work combines the synthesis of heterodinuclear Cu(i)–Ru(ii) analogs of the homodinuclear Cu(i)–Cu(i) targets with spectroscopic analysis and electronic structure calculations to first disentangle the dynamics at individual metal sites by taking advantage of the element and site specificity of X-ray absorption and theoretical methods. The excited state dynamical models developed for the heterodinuclear complexes are then applied to model the more challenging homodinuclear complexes. These results suggest that both intermetallic charge and energy transfer can be observed in an asymmetric dinuclear copper complex in which the ground state redox potentials of the copper sites are offset by only 310 meV. We also demonstrate the ability of several of these complexes to effectively and unidirectionally shuttle energy between different metal centers, a property that could be of great use in the design of broadly absorbing and multifunctional multimetallic photocatalysts. This work provides an important step toward developing both a fundamental conceptual picture and a practical experimental handle with which synthetic chemists, spectroscopists, and theoreticians may collaborate to engineer cheap and efficient photocatalytic materials capable of performing coulombically demanding chemical transformations. PMID:29629153

Atomic and polyatomic molecules at metal surfaces studied by synchrotron far-IR RAIRS

NASA Astrophysics Data System (ADS)

Raval, Rasmita; Roberts, Adam J.; Williams, Jamie; Nunney, Timothy S.; Surman, Mark

1997-10-01

Far-IR Reflection Absorption Infrared Spectroscopy (RAIRS) has been used to probe submonolayers of adsorbates created under clean controlled conditions on small area single crystal surfaces, using the newly commissioned Daresbury 13.3 Far-IR synchrotron beamline. Adsorbed formate species on Cu(110) were studied as an example of an adsorbate for which a large structural data-base already exists in the literature from other surface science techniques. Our high resolution Far-IR data has allowed two distinct vCu-O vibrations to be monitored for 0.25 monolayer of formate adsorbed on Cu(110) at 300 K. We rule out a lower symmetry formate complex giving rise to these vibrations and, instead, attribute the two bands to at least two chemically distinct species at the surface, a possibility that has hitherto not been included in the analyses of this system using other techniques. In addition, we also report the first RAIRS spectrum of the vCu-O stretching vibration for adsorbed atomic O on the Cu(110) surface at 300 K. The dissociative adsorption of oxygen, at room temperature, on this surface is known to induce a massive reconstruction of the surface in which `added' rows of Cu-O-Cu strings form on the surface in the [001] direction to give rise to the (1 X 2) missing row structure. The vCu-O vibration frequency is found to be invariant as a function of coverage, suggesting that the chemical nature of the Cu-O-Cu entity remains essentially unaltered during the growth of the reconstructed phase.

In-vitro study of copper doped SiO2-CaO-P2O5 system for bioactivity and antimicrobial properties

NASA Astrophysics Data System (ADS)

Kaur, Kulwinder; Singh, K. J.; Anand, Vikas; Kaur, Harpreet; Arora, Daljit Singh

2015-08-01

Samples of the xCuO-(45-x)CaO-10P2O5-45SiO2 system (x varies from 0 to 4 mole%) have been synthesized for application as biomaterials to slow or inhibit the growth of living organisms (fungi and other pathogenic microorganisms) by the combination of sol-gel and co-precipitation processes. Prepared samples have been characterized by X-Ray Diffraction, Fourier Transform Infra-Red and Field Emission Scanning Electron Microscopy techniques before and after immersion in simulated body fluid. Antimicrobial activity of samples has been investigated against Staphylococcus aureus. Releasing of Cu2+and other ions in the simulated body fluid has been determined by Atomic Absorption Spectroscopy to ensure the use of prepared material as biomaterial with good antibacterial properties.

On the growth mechanisms of polar (100) surfaces of ceria on copper (100)

NASA Astrophysics Data System (ADS)

Hackl, Johanna; Duchoň, Tomáš; Gottlob, Daniel M.; Cramm, Stefan; Veltruská, Kateřina; Matolín, Vladimír; Nemšák, Slavomír; Schneider, Claus M.

2018-05-01

We present a study of temperature dependent growth of nano-sized ceria islands on a Cu (100) substrate. Low-energy electron microscopy, micro-electron diffraction, X-ray absorption spectroscopy, and photoemission electron microscopy are used to determine the morphology, shape, chemical state, and crystal structure of the grown islands. Utilizing real-time observation capabilities, we reveal a three-way interaction between the ceria, substrate, and local oxygen chemical potential. The interaction manifests in the reorientation of terrace boundaries on the Cu (100) substrate, characteristic of the transition between oxidized and metallic surface. The reorientation is initiated at nucleation sites of ceria islands, whose growth direction is influenced by the proximity of the terrace boundaries. The grown ceria islands were identified as fully stoichiometric CeO2 (100) surfaces with a (2 × 2) reconstruction.

Cooperative cytotoxic activity of Zn and Cu in bovine serum albumin-conjugated ZnS/CuS nano-composites in PC12 cancer cells

NASA Astrophysics Data System (ADS)

Wang, Hua-Jie; Yu, Xue-Hong; Wang, Cai-Feng; Cao, Ying

2013-11-01

Series of self-assembled and mono-dispersed bovine serum albumin (BSA)-conjugated ZnS/CuS nano-composites with different Zn/Cu ratios had been successfully synthesized by a combination method of the biomimetic synthesis and ion-exchange strategy under the gentle conditions. High-resolution transmission electron microscopy observation, Fourier transform infrared spectra and zeta potential analysis demonstrated that BSA-conjugated ZnS/CuS nano-composites with well dispersity had the hierarchical structure and BSA was a key factor to control the morphology and surface electro-negativity of final products. The real-time monitoring by atomic absorption spectroscopy and powder X-ray diffraction revealed that the Zn/Cu ratio of nano-composites could be controlled by adjusting the ion-exchange time. In addition, the metabolic and morphological assays indicated that the metabolic proliferation and spread of rat pheochromocytoma (PC12) cells could be inhibited by nano-composites, with the high anti-cancer activity at a low concentration (4 ppm). What were more important, Zn and Cu in nano-composites exhibited a positive cooperativity at inhibiting cancer cell functions. The microscope observation and biochemical marker analysis clearly revealed that the nano-composites-included lipid peroxidation and disintegration of membrane led to the death of PC12 cells. Summarily, the present study substantiated the potential of BSA-conjugated ZnS/CuS nano-composites as anti-cancer drug.

Interaction of curcumin with Zn(II) and Cu(II) ions based on experiment and theoretical calculation

NASA Astrophysics Data System (ADS)

Zhao, Xue-Zhou; Jiang, Teng; Wang, Long; Yang, Hao; Zhang, Sui; Zhou, Ping

2010-12-01

Curcumin and its complexes with Zn 2+ and Cu 2+ ions were synthesized and characterized by elemental analysis, mass spectroscopy, IR spectroscopy, UV spectroscopy, solution 1H and solid-state 13C NMR spectroscopy, EPR spectroscopy. In addition, the density functional theory (DFT)-based UV and 13C chemical shift calculations were also performed to view insight into those compound structures and properties. The results show that curcumin easily chelate the metal ions, such as Zn 2+ and Cu 2+, and the Cu(II)-curcumin complex has an ability to scavenge free-radicals. We demonstrated the differences between Zn(II)-curcumin and Cu(II)-curcumin complexes in structure and properties, enhancing the comprehensions about the curcumin roles in the Alzhermer's disease treatment.

Spectroscopy peculiarities of thermal plasma of electric arc discharge between electrodes with Zn admixtures

NASA Astrophysics Data System (ADS)

Semenyshyn, R. V.; Veklich, A. N.; Babich, I. L.; Boretskij, V. F.

2014-10-01

Plasma of the free burning electric arc between Ag-SnO2-ZnO composite electrodes as well as brass electrodes were investigated. The plasma temperature distributions were obtained by Boltzmann plot method involving Cu I, Ag I or Zn I spectral line emissions. The electron density distributions were obtained from the width and from absolute intensity of spectral lines. The laser absorption spectroscopy was used for measurement of copper atom concentration in plasma. Plasma equilibrium composition was calculated using two independent groups of experimental values (temperature and copper atom concentration, temperature and electron density). It was found that plasma of the free burning electric arc between brass electrodes is in local thermodynamical equilibrium. The experimental verification of the spectroscopic data of Zn I spectral lines was carried out.

Mineral content of the honey produced in Zulia state, Venezuela.

PubMed

Sulbarán de Ferrer, Betzabé; Ojeda de Rodríguez, Graciela; Peña, Jorge; Martínez, Janeth; Morán, María

2004-09-01

The mineral content of the honey produced in five zones of the Zulia state, Venezuela, during dry and rainy seasons was determined. The analyzed elements were: sodium, potassium (by emission spectroscopy), calcium, magnesium, copper, iron, manganese (by atomic absorption spectroscopy), phosphorus (phosphate ions, by colorimetric method), and ash content of raw honey samples directly collected from different beekeepers. The mean values for Na, K, Ca, Mg, Cu, Fe, Mn, and P were 353+84; 1774+138; 237+66; 52+24; 0.76+0.43; 13.5+10.23; 0.92+0.42 and 1642+323 mg/kg respectively. The mean ash content was 0.431+0.15%. Potassium was the most abundant of the elements determined. This results confirm that Zulian honey can be considered a good source of minerals.

Interfacial Cu + promoted surface reactivity: Carbon monoxide oxidation reaction over polycrystalline copper-titania catalysts

DOE PAGES

Senanayake, S. D.; Pappoe, N. A.; Nguyen-Phan, T. -D.; ...

2016-10-01

We have studied the catalytic carbon monoxide (CO) oxidation (CO+0.5O2 → CO2) reaction using a powder catalyst composed of both copper (5wt% loading) and titania (CuOx-TiO2). Our study was focused on revealing the role of Cu, and the interaction between Cu and TiO2, by systematic comparison between two nanocatalysts, CuOx-TiO2 and pure CuOx. We interrogated these catalysts under in situ conditions using X-ray Diffraction (XRD), X-ray Absorption Fine Structure (XAFS) and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) to probe the structure and electronic properties of the catalyst at all stages of the reaction and simultaneously probe the surface statesmore » or intermediates of this reaction. With the aid of several ex situ characterization techniques including Transmission Electron Microscopy (TEM), the local catalyst morphology and structure was also studied. Our results show that a CuOx-TiO2 system is more active than bulk CuOx for the CO oxidation reaction due to its lower onset temperature and better stability at higher temperatures. Our results also suggests that a surface Cu+ species observed in the CuOx-TiO2 interface are likely to be a key player in the CO oxidation mechanism, while implicating that the stabilization of this species is probably associated with the oxide-oxide interface. Both in situ DRIFTS and XAFS measurements reveal that there is likely to be a Cu(Ti)-O mixed oxide at this interface. We discuss the nature of this Cu(Ti)-O interface and interpret its role on the CO oxidation reaction.« less

High Electrochemical Sensitivity of TiO2- x Nanosheets and an Electron-Induced Mutual Interference Effect toward Heavy Metal Ions Demonstrated Using X-ray Absorption Fine Structure Spectra.

PubMed

Zhou, Wen-Yi; Li, Shan-Shan; Song, Jie-Yao; Jiang, Min; Jiang, Tian-Jia; Liu, Jin-Yun; Liu, Jin-Huai; Huang, Xing-Jiu

2018-04-03

Mutual interference is a severe issue that occurs during the electrochemical detection of heavy metal ions. This limitation presents a notable drawback for its high sensitivity to specific targets. Here, we present a high electrochemical sensitivity of ∼237.1 μA cm -2 μM -1 toward copper(II) [Cu(II)] based on oxygen-deficient titanium dioxide (TiO 2- x ) nanosheets. We fully demonstrated an atomic-level relationship between electrochemical behaviors and the key factors, including the high-energy (001) facet percentage, oxygen vacancy concentration, surface -OH content, and charge carrier density, is fully demonstrated. These four factors were quantified using Raman, electron spin resonance, X-ray photoelectron spectroscopy spectra, and Mott-Schottky plots. In the mutual interference investigation, we selected cadmium(II) [Cd(II)] as the target ion because of the significant difference in its stripping potential (∼700 mV). The results show that the Cd(II) can enhance the sensitivity of TiO 2- x nanosheets toward Cu(II), exhibiting an electron-induced mutual interference effect, as demonstrated by X-ray absorption fine structure spectra.

The effect of administration of copper nanoparticles to chickens in drinking water on estimated intestinal absorption of iron, zinc, and calcium.

PubMed

Ognik, Katarzyna; Stępniowska, Anna; Cholewińska, Ewelina; Kozłowski, Krzysztof

2016-09-01

Copper nanoparticles used as a dietary supplement for poultry could affect the absorption of mineral elements. Hence the aim of the study was to determine the effect of administration of copper nanoparticles to chickens in drinking water on intestinal absorption of iron, zinc, and calcium. The experiment was carried out on 126 chicks assigned to seven experimental groups of 18 birds each (3 replications of 6 individuals each). The control group (G-C) did not receive copper nanoparticles. Groups: Cu-5(7), Cu-10(7), and Cu-15(7) received gold nanoparticles in their drinking water in the amounts of 5 mg/L for group Cu-5(7), 10 mg/L for group Cu-10(7), and 15 mg/L for group Cu-15(7) during 8 to 14, 22 to 28, and 36 of 42 days of the life of the chicks. The birds in groups Cu-5(3), Cu-10(3), and Cu-15(3) received copper nanoparticles in the same amounts, but only during 8 to 10, 22 to 24, and 36 to 38 days of life. Blood for analysis was collected from the wing vein of all chicks at the age of 42 days. After the rearing period (day 42), six birds from each experimental group with body weight similar to the group average were slaughtered. The carcasses were dissected and samples of the jejunum were collected for analysis of absorption of selected minerals. Mineral absorption was tested using the in vitro gastrointestinal sac technique. Oral administration of copper nanoparticles to chickens in the amount of 5, 10, and 15 mg/L led to accumulation of this element in the intestinal walls. The highest level of copper nanoparticles applied increased Cu content in the blood plasma of the birds. The in vitro study suggests that copper accumulated in the intestines reduces absorption of calcium and zinc, but does not affect iron absorption. © 2016 Poultry Science Association Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffeditz, William L.; Katz, Michael J.; Deria, Pravas

Dye-sensitized solar cells (DSCs) are an established alternative photovoltaic technology that offers numerous potential advantages in solar energy applications. However, this technology has been limited by the availability of molecular redox couples that are both noncorrosive/nontoxic and do not diminish the performance of the device. In an effort to overcome these shortcomings, a copper-containing redox shuttle derived from 1,8-bis(2'-pyridyl)-3,6-dithiaoctane (PDTO) ligand and the common DSC additive 4-tert-butylpyridine (TBP) was investigated. Electrochemical measurements, single-crystal X-ray diffraction, and absorption and electron paramagnetic resonance spectroscopies reveal that, upon removal of one metal-centered electron, PDTO-enshrouded copper ions completely shed the tetradentate PDTO ligand andmore » replace it with four or more TBP ligands. Thus, the Cu(I) and Cu(II) forms of the electron shuttle have completely different coordination spheres and are characterized by widely differing Cu(II/I) formal potentials and reactivities for forward versus reverse electron transfer. Notably, the coordination-sphere replacement process is fully reversed upon converting Cu(II) back to Cu(I). In cells featuring an adsorbed organic dye and a nano- and mesoparticulate, TiO2-based, photoelectrode, the dual species redox shuttle system engenders performance superior to that obtained with shuttles based on the (II/I) forms of either of the coordination complexes in isolation.« less

Significance of out-of-plane electronic contributions in Bi-cuprates studied by resonant photoelectron spectroscopy at the Cu2p edge

NASA Astrophysics Data System (ADS)

Janowitz, Christoph; Schmeißer, Dieter

2018-04-01

In high-temperature superconductors with a layered crystal structure, the copper-oxygen planes are commonly considered to dominate the electronic properties around the Fermi energy. As a consequence, out-of-plane contributions are often neglected in the description of these materials. Here we report on a resonant photoemission study of Pb0,4Bi1,6Sr2,0CaCu2O8 ((Pb, Bi)-2212) and Pb0,6Bi1,4Sr1.5La0.5CuO6 ((Pb, Bi)-2201)) single crystals to unravel the resonant decay mechanisms at the Cu2p absorption edge. We find evidence for a pronounced polarization dependence caused by two different Auger processes for in-plane and out-of-plane orientations. We deduce that the lowest energy valence state—which is involved in the two Auger processes—consists of three-dimensional contributions by admixed out-of-plane Sr, Bi, and O2p states. It also suggests that the doping-induced charge density is dynamic, fluctuating within the Cu-O plane, and spills out perpendicular to it. This suggests that out-of-plane electronic degrees of freedom should be included in future consistent theoretical models of these materials.

Wheat flour confectionery products as a source of inorganic nutrients: zinc and copper contents in hard biscuits.

PubMed

Sebecić, Blazenka; Vedrina-Dragojević, Irena

2004-04-01

Cereal-based confectionery products being consumed through whole human life are considered mainly to be a source of carbohydrates, that is energy, although cereals are a rich source of minerals as well. To evaluate some hard biscuits produced in Croatia as a source of different trace elements in nutrition, in this study Zn and Cu contents were determined in classic wheat flour biscuits and in dietetic biscuits enriched with whole wheat grain flour or whole wheat grain grits, soya flour and skimmed milk. Zn was determined by flame atomic absorption spectrometry (AAS); Cu was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The results show that the Zn content in different kinds of biscuits ranges from 5.89 up to 17.64 mg/kg and the Cu content ranges from 1.15 up to 2.79 mg/kg depending on the type of wheat milling products and mineral content of other ingredients used. Enriched dietetic biscuits produced from wheat flour type 850 and whole wheat grain flour and/or soya flour and skimmed milk were almost 200% and 150% higher in Zn and Cu, respectively, in comparison to classic white wheat flour biscuits and can be considered as good sources of Zn and Cu in nutrition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Streltsov, Victor A.; Titmuss, Stephen J.; Epa, V. Chandana

Neurodegeneration observed in Alzheimer disease (AD) is believed to be related to the toxicity from reactive oxygen species (ROS) produced in the brain by the amyloid-{beta} (A{beta}) protein bound primarily to copper ions. The evidence for an oxidative stress role of A{beta}-Cu redox chemistry is still incomplete. Details of the copper binding site in A{beta} may be critical to the etiology of AD. Here we present the structure determined by combining x-ray absorption spectroscopy (XAS) and density functional theory analysis of A{beta} peptides complexed with Cu{sup 2+} in solution under a range of buffer conditions. Phosphate-buffered saline buffer salt (NaCl)more » concentration does not affect the high-affinity copper binding mode but alters the second coordination sphere. The XAS spectra for truncated and full-length A{beta}-Cu{sup 2+} peptides are similar. The novel distorted six-coordinated (3N3O) geometry around copper in the A{beta}-Cu{sup 2+} complexes include three histidines: glutamic, or/and aspartic acid, and axial water. The structure of the high-affinity Cu{sup 2+} binding site is consistent with the hypothesis that the redox activity of the metal ion bound to A{beta} can lead to the formation of dityrosine-linked dimers found in AD.« less

Imaging Catalytic Activation of CO 2 on Cu 2O (110): A First-Principles Study

DOE PAGES

Li, Liang; Zhang, Rui; Vinson, John; ...

2018-03-05

Balancing global energy needs against increasing greenhouse gas emissions requires new methods for efficient CO 2 reduction. While photoreduction of CO 2 is a viable approach for fuel generation, the rational design of photocatalysts hinges on precise characterization of the surface catalytic reactions. Cu 2O is a promising next-generation photocatalyst, but the atomic-scale description of the interaction between CO 2 and the Cu 2O surface is largely unknown, and detailed experimental measurements are lacking. In this study, density-functional-theory (DFT) calculations have been performed to identify the Cu 2O (110) surface stoichiometry that favors CO 2 reduction. To facilitate interpretation ofmore » scanning tunneling microscopy (STM) and X-ray absorption near-edge structures (XANES) measurements, which are useful for characterizing catalytic reactions, we present simulations based on DFT-derived surface morphologies with various adsorbate types. STM and XANES simulations were performed using the Tersoff Hamann approximation and Bethe-Salpeter equation (BSE) approach, respectively. The results provide guidance for observation of CO 2 reduction reaction on, and rational surface engineering of, Cu 2O (110). In conclusion, they also demonstrate the effectiveness of computational image and spectroscopy modeling as a predictive tool for surface catalysis characterization.« less

Active-Site Environment of Copper-Bound Human Amylin Relevant to Type 2 Diabetes.

PubMed

Seal, Manas; Dey, Somdatta Ghosh

2018-01-02

Type 2 diabetes mellitus (T2Dm) is characterized by reduced β cell mass and amyloid deposits of human islet amyloid polypeptide (hIAPP) or amylin, a 37 amino acid containing peptide around pancreatic β cells. The interaction of copper (Cu) with amylin and its mutants has been studied in detail using absorption, circular dichroism, electron paramagnetic resonance spectroscopy, and cyclic voltammetry. Cu binds amylin in a 1:1 ratio, and the binding domain lies within the first 19 amino acid residues of the peptide. Depending on the pH of the medium, Cu-amylin shows the formation of five pH-dependent components (component IV at pH 4.0, component III at pH 5.0, component II at pH 6.0, component I at pH 8.0, and another higher pH component above pH 9.0). The terminal amine, His18, and amidates are established as key residues in the peptide that coordinate the Cu center. The physiologically relevant components I and II can generate H 2 O 2 , which can possibly account for the enhanced toxicity of amylin in the presence of Cu, causing damage of the β cells of the pancreas via oxidative stress.

Decomposition of L a 2 – x S r x Cu O 4 into several L a 2 O 3 phases at elevated temperatures in ultrahigh vacuum inside a transmission electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeong, Jong Seok; Wu, Wangzhou; Topsakal, Mehmet

Here, we report the decomposition of La 2–xSr xCuO 4 into La 2O 3 and Cu nanoparticles in ultrahigh vacuum, observed by in situ heating experiments in a transmission electron microscope. The analysis of electron diffraction data reveals that the phase decomposition process starts at about 150°C and is considerably expedited in the temperature range of 350°C–450°C. Two major resultant solid phases are identified as metallic Cu and La 2O 3 by electron diffraction, simulation, and electron energy-loss spectroscopy (EELS) analyses. With the aid of calculations, La 2O 3 phases are further identified to be derivatives of a fluorite structure—fluorite,more » pyrochlore, and (distorted) bixbyite—characterized by different oxygen-vacancy order. Additionally, the bulk plasmon energy and the fine structures of the O K and LaM 4,5 EELS edges are reported for these structures, along with simulated O K x-ray absorption near-edge structure. The resultant Cu nanoparticles and La 2O 3 phases remain unchanged after cooling to room temperature.« less

Fabrication of copper decorated tungsten oxide-titanium oxide nanotubes by photochemical deposition technique and their photocatalytic application under visible light

NASA Astrophysics Data System (ADS)

Momeni, Mohamad Mohsen

2015-12-01

Copper decorated WO3-TiO2 nanotubes (Cu/WTNs) with a high photocatalytic activity were prepared by anodizing and photochemical deposition. Highly ordered WO3-TiO2 nanotubes (WTNs) on pure titanium foils were successfully fabricated by electrochemical anodizing and copper deposited on these nanotubes (Cu/WTNs) by photoreduction method. The resulting samples were characterized by various methods. Only the anatase phase was detected by X-ray diffraction analysis. The presence of copper in the structure of thin films was confirmed by energy dispersive X-ray spectrometry and X-ray diffraction. The extension of optical absorption into the visible region of as-prepared films was indicated by UV/Vis spectroscopy. The degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of the obtained samples. Results showed that the photocatalytic activity of Cu/WTNs samples is higher than bare WTNs sample. Kinetic research showed that the reaction rate constant of Cu/WTNs is approximately 2.5 times higher than the apparent reaction rate constant of bare WTNs. These results not only offer an economical method for constructing Cu/WTNs photocatalysts, but also shed new insight on the rational design of a low cost and high-efficiency photocatalyst for environmental remediation.

Imaging Catalytic Activation of CO 2 on Cu 2O (110): A First-Principles Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Liang; Zhang, Rui; Vinson, John

Balancing global energy needs against increasing greenhouse gas emissions requires new methods for efficient CO 2 reduction. While photoreduction of CO 2 is a viable approach for fuel generation, the rational design of photocatalysts hinges on precise characterization of the surface catalytic reactions. Cu 2O is a promising next-generation photocatalyst, but the atomic-scale description of the interaction between CO 2 and the Cu 2O surface is largely unknown, and detailed experimental measurements are lacking. In this study, density-functional-theory (DFT) calculations have been performed to identify the Cu 2O (110) surface stoichiometry that favors CO 2 reduction. To facilitate interpretation ofmore » scanning tunneling microscopy (STM) and X-ray absorption near-edge structures (XANES) measurements, which are useful for characterizing catalytic reactions, we present simulations based on DFT-derived surface morphologies with various adsorbate types. STM and XANES simulations were performed using the Tersoff Hamann approximation and Bethe-Salpeter equation (BSE) approach, respectively. The results provide guidance for observation of CO 2 reduction reaction on, and rational surface engineering of, Cu 2O (110). In conclusion, they also demonstrate the effectiveness of computational image and spectroscopy modeling as a predictive tool for surface catalysis characterization.« less

Decomposition of L a 2 – x S r x Cu O 4 into several L a 2 O 3 phases at elevated temperatures in ultrahigh vacuum inside a transmission electron microscope

DOE PAGES

Jeong, Jong Seok; Wu, Wangzhou; Topsakal, Mehmet; ...

2018-05-15

Here, we report the decomposition of La 2–xSr xCuO 4 into La 2O 3 and Cu nanoparticles in ultrahigh vacuum, observed by in situ heating experiments in a transmission electron microscope. The analysis of electron diffraction data reveals that the phase decomposition process starts at about 150°C and is considerably expedited in the temperature range of 350°C–450°C. Two major resultant solid phases are identified as metallic Cu and La 2O 3 by electron diffraction, simulation, and electron energy-loss spectroscopy (EELS) analyses. With the aid of calculations, La 2O 3 phases are further identified to be derivatives of a fluorite structure—fluorite,more » pyrochlore, and (distorted) bixbyite—characterized by different oxygen-vacancy order. Additionally, the bulk plasmon energy and the fine structures of the O K and LaM 4,5 EELS edges are reported for these structures, along with simulated O K x-ray absorption near-edge structure. The resultant Cu nanoparticles and La 2O 3 phases remain unchanged after cooling to room temperature.« less

ESR and nonresonant microwave absorption of ErBa2Cu3O(7-delta) and HoBa2Cu3O(7-delta) single crystals

NASA Astrophysics Data System (ADS)

Tagaya, Kimihito; Fukuoka, Nobuo; Nakanishi, Shigemitsu

1990-12-01

ESR measurements were performed for ErBa2Cu3O(7-delta) and HoBa2Cu3O(7-delta) single crystals from 77 K to room temperature. The ESR signals of Er2BaCuO5 and Ho2BaCuO5 were observed, and their temperature variations were investigated. Nonresonant microwave absorption was also observed below the superconducting critical temperature of 93 K. The principal values of lower critical field were determined.

Effect of alkaline earth modifier on the optical and structural properties of Cu2+ doped phosphate glasses as a bandpass filter

NASA Astrophysics Data System (ADS)

Farouk, M.; Samir, A.; El Okr, M.

2018-02-01

Glasses of composition [16RO-3Al2O3sbnd 6CuOsbnd 20Na2Osbnd 55P2O5], where R is the alkaline earth (R = Mg, Ca, Sr and Ba mol. %), were prepared by conventional melt quenching technique. The glass samples were characterized by X-ray diffraction, infrared spectroscopy, and spectrophotometer. XRD patterns show no sharp peaks indicating the non-crystalline nature of the prepared glasses. The density and molar volume of the glass systems were determined in order to study their structures. These results revealed that addition of alkaline earth elements leads to the formation of non-bridging oxygens (NBOs) and expands (opens up) the structure. The infrared spectra were analyzed to quantify the present phosphate groups. The optical absorption spectra of Cu2+ ions show the characteristic broadband single of Cu2+ ions in octahedral symmetry. The band gap was estimated following two methodologies. The first method considers the band edge of the transmission, while the second approach relays on the estimated values of the optical constants. A decent agreement for the band gap values using the two methods was obtained.

Preliminary results of human PrPC protein studied by spectroscopic techniques

NASA Astrophysics Data System (ADS)

Nowakowski, Michał; Czapla-Masztafiak, Joanna; Kozak, Maciej; Zhukov, Igor; Zhukova, Lilia; Szlachetko, Jakub; Kwiatek, Wojciech M.

2017-11-01

Neurodegenerative diseases are one of the malfunctions of human nervous system, being a class of complex and prominent pathologies. The human prion Protease Resistant Protein (PrP) is protein regulating copper metabolism in mammalian cells through binding of Cu(II) ions to specific fragments. Nowadays misfolding of this protein is associated with development of prion diseases. Therefore, it is crucial to obtain structural information about coordination of Cu(II) by PrP protein. Herein, we report X-ray absorption spectroscopy (XAS) measurements, carried out on SuperXAS beamline (SLS, PSI Villigen) on PrPC-Cu(II) complexes. Obtained results were compared with theoretical predictions done by FEFF 9.6 software. Complementary to XAS data, Atomic Force Microscopy (AFM) measurements were conducted to obtain low resolution structural information about prepared sample that allow to develop protocol of fixing PrPC molecules on solid substrate used for further experiments. It has been established that folded C-terminal domain of PrPC protein has around 5 nm in diameter. Presented results showed that both XAS and AFM methods are useful tools in detailed examination of complexes of human PrPC either with Cu(II) or with other divalent metal ions.

Synthesis, structural, optical and electrical properties of metal nanoparticle-rare earth ion dispersed in polymer film

NASA Astrophysics Data System (ADS)

Kumar, Brijesh; Kaur, Gagandeep; Singh, P.; Rai, S. B.

2013-03-01

Cu-nanoparticles have been prepared by ablating a copper target submerged in benzene with laser pulses of Nd:YAG (wavelength: 355, 532 nm and 1,064 nm). Colloidal nanoparticles have been characterized by UV-Vis spectroscopy and transmission electron microscopy. The obtained radius for the nanoparticles prepared using 1,064 nm irradiation lies in the range 15-30 nm, with absorption peak at 572 nm. Luminescence properties of Tb3+ ions in the presence and absence of Cu-nanoparticles have been investigated using 355 nm excitation. An enhancement in luminescence of Tb3+ by local field effect causing increase in lifetime of 5D4 level of Tb3+ ion has been observed. Frequency and temperature-dependent conductivity of Tb3+ doped PVA thin films with and without Cu-nanoparticles have been measured in the frequency range 20 Hz-1 MHz and in the temperature range 318-338 K (well below its melting temperature). Real part of the conductivity spectra has been explained in terms of power law. The electrical properties of the thin films show a decrease in dc conductivity on incorporation of the Cu-nanoparticles.

Synthesis, characterization and anti-microbial activity of pure, Cu2+ and Cd2+ doped organic NLO l-arginine trifluoroacetate single crystals

NASA Astrophysics Data System (ADS)

Prasanyaa, T.; Haris, M.; Jayaramakrishnan, V.; Amgalan, M.; Mathivanan, V.

2013-10-01

Optically transparent Cu2+ and Cd2+ doped l-arginine trifluoroacetate (LATF) single crystals were grown from its aqueous solution using the slow solvent evaporation technique. The grown crystals were characterized by powder x-ray diffraction to confirm the monoclinic crystal structure. The percentage of transmittance measured using the ultraviolet-visible-near infrared spectrophotometer was found to be more than 80% for doped crystals. The functional group analysis of the grown crystals has been made by Fourier transform infrared spectroscopy. Thermogravimetric/differential thermal analysis was performed for the grown crystals. An atomic absorption study was carried out to determine the presence of Cu2+ and Cd2+. The hardness of the grown crystals was assessed and the results show a significant variation in the hardness value between the pure and doped LATF crystals. The second harmonic generation measurements show that Cu2+ doped LATF is 2.8 times greater and Cd2+ doped is 2.6 times greater than KDP. The anti-bacterial and anti-fungal activities of the title compound were performed using the disc diffusion method against standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillus niger and Aspergillus flavus.

Preparation of Cu2ZnSnS4 nano-crystalline powder by mechano-chemical method

NASA Astrophysics Data System (ADS)

Alirezazadeh, Farzaneh; Sheibani, Saeed; Rashchi, Fereshteh

2018-01-01

Copper zinc tin sulfide (Cu2ZnSnS4, CZTS) is one of the most promising ceramic materials as an absorber layer in solar cells due to its suitable band gap, high absorption coefficient and non-toxic and environmental friendly constituent elements. In this work, nano-crystalline CZTS powder was synthesized by mechanical milling. Elemental powders of Cu, Zn, Sn and were mixed in atomic ratio of 2:1:1:4 according to the stoichiometry of Cu2ZnSnS4 and then milled in a planetary high energy ball mill under argon atmosphere. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffusion reflectance spectroscopy (DRS). XRD results confirm the formation of single-phase CZTS with kesterite structure after 20 h of milling. Also, the mean crystallite size was about 35 nm. SEM results show that after 20 h of milling, the product has a relatively uniform particle size distribution. Optical properties of the product indicate that the band gap of prepared CZTS is 1.6 eV which is near to the optimum value for photovoltaic solar cells showing as a light absorber material in solar energy applications.

Preparation and characterization of copper oxide nanoparticles decorated carbon nanoparticles using laser ablation in liquid

NASA Astrophysics Data System (ADS)

Khashan, K. S.; Jabir, M. S.; Abdulameer, F. A.

2018-05-01

Carbon nanoparticles CNPs ecorated by copper oxide nano-sized particles would be successfully equipped using technique named pulsed laser ablation in liquid. The XRD pattern proved the presence of phases assigned to carbon and different phases of copper oxide. The chemical structure of the as-prepared nanoparticles samples was decided by Energy Dispersive Spectrum (EDS) measurement. EDS analysis results show the contents of Carbon, Oxygen and Copper in the final product. These nanoparticles were spherical shaped with a size distribution 10 to 80 nm or carbon nanoparticles and 5 to 50 nm for carbon decorated copper oxide nanoparticles, according to Transmission Electron Microscopy (TEM) images and particle-size distribution histogram. It was found that after doping with copper oxide, nanoparticles become smaller and more regular in shape. Optical absorption spectra of prepared nanoparticles were measured using UV–VIS spectroscopy. The absorption spectrum of carbon nanoparticles without doping indicates absorption peak at about 228 nm. After doping with copper oxide, absorption shows appearance of new absorption peak at about (254-264) nm, which is referred to the movement of the charge between 2p and 4s band of Cu2+ ions.

Heterojunctions of mixed phase TiO2 nanotubes with Cu, CuPt, and Pt nanoparticles: interfacial band alignment and visible light photoelectrochemical activity

NASA Astrophysics Data System (ADS)

Kar, Piyush; Zhang, Yun; Mahdi, Najia; Thakur, Ujwal K.; Wiltshire, Benjamin D.; Kisslinger, Ryan; Shankar, Karthik

2018-01-01

Anodically formed, vertically oriented, self-organized cylindrical TiO2 nanotube arrays composed of the anatase phase undergo an interesting morphological and phase transition upon flame annealing to square-shaped nanotubes composed of both anatase and rutile phases. This is the first report on heterojunctions consisting of metal nanoparticles (NPs) deposited on square-shaped TiO2 nanotube arrays (STNAs) with mixed rutile and anatase phase content. A simple photochemical deposition process was used to form Cu, CuPt, and Pt NPs on the STNAs, and an enhancement in the visible light photoelectrochemical water splitting performance for the NP-decorated STNAs was observed over the bare STNAs. Under narrow band illumination by visible photons at 410 nm and 505 nm, Cu NP-decorated STNAs performed the best, producing photocurrents 80% higher and 50 times higher than bare STNAs, respectively. Probing the energy level structure at the NP-STNA interface using ultraviolet photoelectron spectroscopy revealed Schottky barrier formation in the NP-decorated STNAs, which assists in separating the photogenerated charge carriers, as also confirmed by longer charge carrier lifetimes in NP-decorated STNAs. While all the NP-decorated STNAs showed enhanced visible light absorption compared to the bare STNAs, only the Cu NPs exhibited a clear plasmonic behavior with an extinction cross section that peaked at 550 nm.

Face specificity and the role of metal adatoms in molecular reorientation at surfaces

NASA Astrophysics Data System (ADS)

Perry, C. C.; Haq, S.; Frederick, B. G.; Richardson, N. V.

1998-07-01

Using reflection absorption infrared spectroscopy (RAIRS), the coverage-dependent reorientation of the benzoate species on the (110) and (111) faces of copper is compared and contrasted. Whereas on Cu(110) benzoate reorients from a flat-lying to an upright orientation with increasing coverage, on Cu(111), at all coverages, benzoate is aligned normal to the surface. The formation of periodic, flat-lying copper-benzoate structures has been attributed to the availability of metal adatoms, which differs dramatically between the (111) and (110) faces. We discuss the face specificity of molecular orientation by comparing calculated formation energies of adatom vacancies from ledges and kink sites on (100), (110) and (111) faces. Further support for this model is given by the evaporation of sodium, either by pre- or post-dosing, onto low-coverage benzoate/Cu(111), which induces benzoate to convert from a perpendicular to a parallel orientation. Likewise, coevaporation of Cu while dosing benzoic acid onto the Cu(111) surface also results in a majority of flat-lying benzoate species. Finally, for adsorption on the p(2×1)O/Cu(110) reconstruction, benzoate occurs only as the upright species, which is consistent with reducing the copper mobility and availability on the (110) face. We therefore suggest the possible role of metal adatoms as a new mechanism in controlling adsorbate orientation and therefore face specificity in surface reactions.

Heterojunctions of mixed phase TiO2 nanotubes with Cu, CuPt, and Pt nanoparticles: interfacial band alignment and visible light photoelectrochemical activity.

PubMed

Kar, Piyush; Zhang, Yun; Mahdi, Najia; Thakur, Ujwal K; Wiltshire, Benjamin D; Kisslinger, Ryan; Shankar, Karthik

2018-01-05

Anodically formed, vertically oriented, self-organized cylindrical TiO 2 nanotube arrays composed of the anatase phase undergo an interesting morphological and phase transition upon flame annealing to square-shaped nanotubes composed of both anatase and rutile phases. This is the first report on heterojunctions consisting of metal nanoparticles (NPs) deposited on square-shaped TiO 2 nanotube arrays (STNAs) with mixed rutile and anatase phase content. A simple photochemical deposition process was used to form Cu, CuPt, and Pt NPs on the STNAs, and an enhancement in the visible light photoelectrochemical water splitting performance for the NP-decorated STNAs was observed over the bare STNAs. Under narrow band illumination by visible photons at 410 nm and 505 nm, Cu NP-decorated STNAs performed the best, producing photocurrents 80% higher and 50 times higher than bare STNAs, respectively. Probing the energy level structure at the NP-STNA interface using ultraviolet photoelectron spectroscopy revealed Schottky barrier formation in the NP-decorated STNAs, which assists in separating the photogenerated charge carriers, as also confirmed by longer charge carrier lifetimes in NP-decorated STNAs. While all the NP-decorated STNAs showed enhanced visible light absorption compared to the bare STNAs, only the Cu NPs exhibited a clear plasmonic behavior with an extinction cross section that peaked at 550 nm.

Self-doping processes between planes and chains in the metal-to-superconductor transition of YBa2Cu3O6.9.

PubMed

Magnuson, M; Schmitt, T; Strocov, V N; Schlappa, J; Kalabukhov, A S; Duda, L-C

2014-11-12

The interplay between the quasi 1-dimensional CuO-chains and the 2-dimensional CuO2 planes of YBa(2)Cu(3)O(6+x) (YBCO) has been in focus for a long time. Although the CuO-chains are known to be important as charge reservoirs that enable superconductivity for a range of oxygen doping levels in YBCO, the understanding of the dynamics of its temperature-driven metal-superconductor transition (MST) remains a challenge. We present a combined study using x-ray absorption spectroscopy and resonant inelastic x-ray scattering (RIXS) revealing how a reconstruction of the apical O(4)-derived interplanar orbitals during the MST of optimally doped YBCO leads to substantial hole-transfer from the chains into the planes, i.e. self-doping. Our ionic model calculations show that localized divalent charge-transfer configurations are expected to be abundant in the chains of YBCO. While these indeed appear in the RIXS spectra from YBCO in the normal, metallic, state, they are largely suppressed in the superconducting state and, instead, signatures of Cu trivalent charge-transfer configurations in the planes become enhanced. In the quest for understanding the fundamental mechanism for high-Tc-superconductivity (HTSC) in perovskite cuprate materials, the observation of such an interplanar self-doping process in YBCO opens a unique novel channel for studying the dynamics of HTSC.

The influence of the precursor compositional ratio on Cu2ZnSnS4 films prepared by using sulfurization of the metallic precursor

NASA Astrophysics Data System (ADS)

Amal, Muhamad I.; Kim, Kyoo Ho

2013-12-01

Cu2ZnSnS4 (CZTS) films were prepared by using the sulfurization of sputtered metallic precursors. The compositional ratio of the CZTS films was slightly different compared to their initial metallic precursors due to elemental loss during annealing. The Cu/(Zn+Sn) ratio for the CZTS-1, CZTS-2 and CZTS-3 films were 0.91, 1.06 and 1.21, respectively. In addition, all films had a compositional ratio of Zn/Sn >1. The grain sizes of the CZTS films increased with increasing Cu ratio. X-ray diffraction and Raman spectroscopy showed that the CZTS films with an excess of copper and zinc had secondary phases of Cu2SnS3 and ZnS. The optical band gap and absorption coefficient for all CZTS films in the range of the experimental compositions were calculated to be 1.5 eV and >104 cm-1, respectively. The presence of secondary phases related to compositional ratio in the CZTS films influenced the electrical properties. The CZTS-1 film with a Cu-poor and Zn-rich composition whose a carrier concentration, an electrical mobility, and a resistivity values were 2.29 × 1018 cm-3, 10.29 cm2 V-1 s-1, 3.16 Ω cm, is the most suitable for solar-cell applications.

Macroscopic and molecular approaches of enrofloxacin retention in soils in presence of Cu(II).

PubMed

Graouer-Bacart, Mareen; Sayen, Stéphanie; Guillon, Emmanuel

2013-10-15

The co-adsorption of copper and the fluoroquinolone antibiotic enrofloxacin (ENR) at the water-soil interface was studied by means of batch adsorption experiments, and extended X-ray absorption fine structure (EXAFS) spectroscopy. The system was investigated over a pH range between 6 and 10, at different contact times, ionic strengths, and ENR concentrations. Adsorption coefficient - Kd - was determined at relevant environmental concentrations and the value obtained in water at a ionic strength imposed by the soil and at soil natural pH was equal to 0.66Lg(-1). ENR adsorption onto the soil showed strong pH dependence illustrating the influence of the electrostatic interactions in the sorption processes. The simultaneous co-adsorption of ENR and Cu(II) on the soil was also investigated. The presence of Cu(II) strongly influenced the retention of the antibiotic, leading to an increase up to 35% of adsorbed ENR amount. The combined quantitative and spectroscopic results showed that Cu(II) and ENR directly interacted at the water-soil interface to form ternary surface complexes. Cu K-edge EXAFS data indicated a molecular structure where the carboxylate and carbonyl groups of ENR coordinate to Cu(II) to form a 6-membered chelate ring and where Cu(II) bridges between ENR and the soil surface sites. Cu(II) bonds bidentately to the surface in an inner-sphere mode. Thus, the spectroscopic data allowed us to propose the formation of ternary surface complexes with the molecular architecture soil-Cu(II)-ENR. Copyright © 2013 Elsevier Inc. All rights reserved.

Reduced graphene oxide wrapped Cu2O supported on C3N4: An efficient visible light responsive semiconductor photocatalyst

NASA Astrophysics Data System (ADS)

Ganesh Babu, S.; Vinoth, R.; Surya Narayana, P.; Bahnemann, Detlef; Neppolian, B.

2015-10-01

Herein, Cu2O spheres were prepared and encapsulated with reduced graphene oxide (rGO). The Cu2O-rGO-C3N4 composite covered the whole solar spectrum with significant absorption intensity. rGO wrapped Cu2O loading caused a red shift in the absorption with respect to considering the absorption of bare C3N4. The photoluminescence study confirms that rGO exploited as an electron transport layer at the interface of Cu2O and C3N4 heterojunction. Utmost, ˜2 fold synergistic effect was achieved with Cu2O-rGO-C3N4 for the photocatalytic reduction of 4-nitrophenol to 4-aminophenol in comparison with Cu2O-rGO and C3N4. The Cu2O-rGO-C3N4 photocatalyst was reused for four times without loss in its activity.

Optical absorption and disorder in delafossites

DOE PAGES

Senty, Tess R.; Haycock, Barry; Lekse, Jonathan; ...

2017-07-06

Here, we present compelling experimental results of the optical characteristics of transparent oxide CuGaO 2 and related CuGa 1-xFe xO 2 (with 0.00 ≤ x ≤ 0.05) alloys, whereby the forbidden electronic transitions for CuGaO 2 become permissible in the presence of B-site (Ga sites) alloying with Fe. Our computational structural results imply a correlation between the global strain on the system and a decreased optical absorption edge. However, herein, we show that the relatively ordered CuGa 1-xFe xO 2 (for 0.00 ≤ x ≤ 0.04) structures exhibit much weaker vis-absorption compared to the relatively disordered CuGa 0.95Fe 0.05O 2.

Near-infrared radiation absorption properties of covellite (CuS) using first-principles calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Lihua, E-mail: xiaolihua@git.edu.cn; College of Physics and Information Science, Hunan Normal University, Changsha 410081; Guizhou Special Functional Materials 2011 Collaborative Innovation Center, Guizhou Institute of Technology, Guiyang 550003

2016-08-15

First-principles density functional theory was used to investigate the electronic structure, optical properties and the origin of the near-infrared (NIR) absorption of covellite (CuS). The calculated lattice constant and optical properties are found to be in reasonable agreement with experimental and theoretical findings. The electronic structure reveals that the valence and conduction bands of covellite are determined by the Cu 3d and S 3p states. By analyzing its optical properties, we can fully understand the potential of covellite (CuS) as a NIR absorbing material. Our results show that covellite (CuS) exhibits NIR absorption due to its metal-like plasma oscillation inmore » the NIR range.« less

Optical absorption and electrical properties of MPc (M =Fe, Cu, Zn)-TCNQ interfaces for optoelectronic applications

NASA Astrophysics Data System (ADS)

Sánchez Vergara, M. E.; Medrano Gallardo, D.; Vera Estrada, I. L.; Jiménez Sandoval, O.

2018-04-01

This research is related to the growth and characterization of doped molecular semiconductor metallophthalocyanine-tetracyanoquinodimethane (MPc-TCNQ) films, with M = Fe, Zn, Cu. FT-IR and Raman spectroscopies were employed to study the chemical interactions taking place in the MPc-TCNQ films. XRD was carried out to determine the crystalline structure present in the samples, due to the facility of the MPcs to be in alpha and/or beta phases. The thin films were analized by SEM and UV-vis spectroscopy in order to study their morphological and optical properties. The absorption spectra recorded in the UV-Vis region for the deposited samples showed two bands, namely the Q and Soret bands. The absorption coefficient (α) and photon energy (hν) were calculated from the UV-vis spectra, to in turn determine the optic activation energy in each film and its semiconductor behavior. The values obtained for direct transitions due to the crystallinity of the films were: 1.2, 1.4 and 2 eV for FePc-TCNQ (MMFe), ZnPc-TCNQ (MMZn) and CuPc-TCNQ (MMCu), respectively. Additionally, I-V characteristics have been obtained from fabricated glass/ITO/MM/Ag devices using ohmic contacts both after annealing. The electrical properties of the devices, e.g. carrier mobility and concentration of thermally generated holes, were extracted from the J-V characteristics. The results show that the conduction process is ohmic for the MMZn and MMCu devices, at low voltages, while at high voltages, a space-charge-limited conduction (SCLC) is present. The effect of temperature on conductivity was also measured in these samples and the lower thermal activation energy calculated was 0.37 eV for MMZn. Moreover, it was found that the temperature-dependent electric current is always higher for the MMZn device and suggests a semiconductor-like behavior with an important conductivity of the order of 103 S cm-1. Anyhow, in terms not only of electric properties, but also of optic behavior, the results suggest that all three devices manufactured, MMFe, MMCu and MMZn, are of potential use in optoelectronics. The doping effect of TCNQ favors the electronic transport, most likely due to the formation of conduction channels caused by the anisotropy induced by the dopant.

Electronic absorption band broadening and surface roughening of phthalocyanine double layers by saturated solvent vapor treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jinhyun; Yim, Sanggyu, E-mail: sgyim@kookmin.ac.kr

2012-10-15

Variations in the electronic absorption (EA) and surface morphology of three types of phthalocyanine (Pc) thin film systems, i.e. copper phthalocyanine (CuPc) single layer, zinc phthalocyanine (ZnPc) single layer, and ZnPc on CuPc (CuPc/ZnPc) double layer film, treated with saturated acetone vapor were investigated. For the treated CuPc single layer film, the surface roughness slightly increased and bundles of nanorods were formed, while the EA varied little. In contrast, for the ZnPc single layer film, the relatively high solubility of ZnPc led to a considerable shift in the absorption bands as well as a large increase in the surface roughnessmore » and formation of long and wide nano-beams, indicating a part of the ZnPc molecules dissolved in acetone, which altered their molecular stacking. For the CuPc/ZnPc film, the saturated acetone vapor treatment resulted in morphological changes in mainly the upper ZnPc layer due to the significantly low solubility of the underlying CuPc layer. The treatment also broadened the EA band, which involved a combination of unchanged CuPc and changed ZnPc absorption.« less

Interplay of metals and bromine with dioxin-related compounds concentrated in e-waste open burning soil from Agbogbloshie in Accra, Ghana.

PubMed

Fujimori, Takashi; Itai, Takaaki; Goto, Akitoshi; Asante, Kwadwo A; Otsuka, Masanari; Takahashi, Shin; Tanabe, Shinsuke

2016-02-01

Open burning of electronic waste (e-waste) releases various metals and organohalogen compounds in the environment. Here we investigated the interplay of metals (Cu, Pb, Zn, Fe, Co, and Sr) and bromine (Br) in the formation of dioxin-related compounds (DRCs), including polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs), as well as non-regulated DRCs such as polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) and their monobrominated PCDD/Fs in soils sampled from open burning e-waste sites at Agbogbloshie in Accra, Ghana. The predominant DRCs were PBDFs, PCDFs, PCDDs, and DL-PCBs. Statistical analyzes, X-ray absorption spectroscopy, and the PCDF/PCDD ratio suggested possible formation paths of PCDD/Fs and DL-PCBs by catalytic behaviors of copper chlorides (CuCl, CuCl2, and Cu2(OH)3Cl) and thermal breakdown of polyvinyl chloride. Predominant formation of brominated furans may be derived from electron transfer from intermediates of PBDE to copper, Cu(II) → Cu(I). Lead chloride also contributed to generate DRCs and may become highly bioaccessible through the open burning of e-waste. The main zinc species (ZnCl2 and ZnS) suggested a possible relationship to generate DRCs and specific zinc source such as tire burning. Cu, Pb, Zn, and Br contained in various e-wastes, wires/cables, plastics, and tires strongly influenced generation of many DRCs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Re-evaluating the Cu K pre-edge XAS transition in complexes with covalent metal–ligand interactions† †Electronic supplementary information (ESI) available: Experimental methods; UV-vis absorption spectrum and crystallographic data for 3; fits to Cu K pre-edge XANES spectra; details of DFT, CASSCF, and MR-DDCI3 computational experiments; optimized atomic coordinates for all complexes. CCDC 1031118 and 1031119. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc03294b Click here for additional data file. Click here for additional data file.

PubMed Central

Williams, Kamille D.; Dai, Xuliang; Sproules, Stephen; DeBeer, Serena

2015-01-01

Three [Me2NN]Cu(η2-L2) complexes (Me2NN = HC[C(Me)NAr]2; L2 = PhNO (2), (3), PhCH 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 CH2 (4); Ar = 2,6-Me2-C6H3; ArF = 3,5-(CF3)2-C6H3) have been studied by Cu K-edge X-ray absorption spectroscopy, as well as single- and multi-reference computational methods (DFT, TD-DFT, CASSCF, MRCI, and OVB). The study was extended to a range of both known and theoretical compounds bearing 2p-element donors as a means of deriving a consistent view of how the pre-edge transition energy responds in systems with significant ground state covalency. The ground state electronic structures of many of the compounds under investigation were found to be strongly influenced by correlation effects, resulting in ground state descriptions with majority contributions from a configuration comprised of a Cu(ii) metal center anti-ferromagentically coupled to radical anion O2, PhNO, and ligands. In contrast, the styrene complex 4, which displays a Cu K pre-edge transition despite its formal d10 electron configuration, exhibits what can best be described as a Cu(i):(styrene)0 ground state with strong π-backbonding. The Cu K pre-edge features for these complexes increase in energy from 1 to 4, a trend that was tracked to the percent Cu(ii)-character in the ground state. The unexpected shift to higher pre-edge transition energies with decreasing charge on copper (Q Cu) contributed to an assignment of the pre-edge features for these species as arising from metal-to-ligand charge transfer instead of the traditional Cu1s → Cu3d designation. PMID:29308158

Intestinal absorption of copper: influence of carbohydrates.

PubMed

Wapnir, R A; Balkman, C

1992-02-01

Macronutrients can modulate the intestinal absorption of trace elements by binding the metal or altering mucosal function. We investigated whether certain simple and complex carbohydrates modify copper (Cu) absorption, using an in vivo perfusion technique in the rat. Corn syrup solids, which contain a mixture of glucose polymers of diverse length, added at either 20 or 50 mosm/kg enhanced Cu absorption from a 31.5 microM (2 mg/liter) Cu solution (128 +/- 11 and 130 +/- 11 pmol/min x cm, respectively, vs 101 +/- 4 pmol/min x cm, P less than 0.05, in the absence of carbohydrate). This was concomitant with a stimulation of net water absorption (1.05 +/- 0.08 and 0.84 +/- 0.08 microliter/min x cm, respectively, vs 0.63 +/- 0.02 microliter/min x cm with no carbohydrate, P less than 0.05). Glucose, fructose, lactose, or sucrose had no influence on Cu absorption, although they altered water exchanges, an effect attributable to a reduction of the outflow component of fluid recirculation. Low concentrations of lactose resulted in a greater accumulation of Cu in the intestinal mucosa (8.75 +/- 0.71 micrograms/g vs 5.77 +/- 0.68 micrograms/g for controls, P less than 0.05). Hence, solutes that moderately stimulate mucosa-to-serosa fluid influx in a progressive manner, such as glucose polymers, may contribute to functionally increase Cu absorption. Conversely, conditions which tend to reduce water inflow or increase water outflow across the small intestinal mucosa, as may occur with high lactose diets or in cases of chronic diarrhea, may have negative effects.

A rapid, partial leach and organic separation for the sensitive determination of Ag, Bi, Cd, Cu, Mo, Pb, Sb, and Zn in surface geologic materials by flame atomic absorption

USGS Publications Warehouse

Viets, J.G.; Clark, J.R.; Campbell, W.L.

1984-01-01

A solution of dilute hydrochloric acid, ascorbic acid, and potassium iodide has been found to dissolve weakly bound metals in soils, stream sediments, and oxidized rocks. Silver, Bi, Cd, Cu, Mo, Pb, Sb, and Zn are selectively extracted from this solution by a mixture of Aliquat 336 (tricaprylyl methyl ammonium chloride) and MIBK (methyl isobutyl ketone). Because potentially interfering major and minor elements do not extract, the organic separation allows interference-free determinations of Ag and Cd to the 0.05 ppm level, Mo, Cu, and Zn to 0.5 ppm, and Bi, Pb, and Sb to 1 ppm in the sample using flame atomic absorption spectroscopy. The analytical absorbance values of the organic solution used in the proposed method are generally enhanced more than threefold as compared to aqueous solutions, due to more efficient atomization and burning characteristics. The leaching and extraction procedures are extremely rapid; as many as 100 samples may be analyzed per day, yielding 800 determinations, and the technique is adaptable to field use. The proposed method was compared to total digestion methods for geochemical reference samples as well as soils and stream sediments from mineralized and unmineralized areas. The partial leach showed better anomaly contrasts than did total digestions. Because the proposed method is very rapid and is sensitive to pathfinder elements for several types of ore deposits, it should be useful for reconnaissance surveys for concealed deposits. ?? 1984.

Photoemission study of absorption mechanisms in Bi2.0Sr1.8Ca0.8La0.3Cu2.1O8+δ, BaBiO3, and Nd1.85Ce0.15CuO4

NASA Astrophysics Data System (ADS)

Lindberg, P. A. P.; Shen, Z.-X.; Wells, B. O.; Dessau, D. S.; Ellis, W. P.; Borg, A.; Kang, J.-S.; Mitzi, D. B.; Lindau, I.; Spicer, W. E.; Kapitulnik, A.

1989-11-01

Photoemission measurements in the constant-final-state (absorption) mode were performed on three different classes of high-temperature superconductors Bi2.0Sr1.8Ca0.8La0.3Cu2.1O8+δ, BaBiO3, and Nd1.85Ce0.15CuO4 using synchrotron radiation from 20 to 200 eV. Absorption signals from all elements but Ce are identified. The results firmly show that the Bi 6s electrons are more delocalized in BaBiO3 than in Bi2.0Sr1.8Ca0.8La0.3Cu2.1O8+δ, in agreement with the results of band-structure calculations. Differences in the absorption signals due to O and Bi excitations between BaBiO3 and Bi2.0Sr1.8Ca0.8La0.3Cu2.1O8+δ are discussed. Delayed absorption onsets attributed to giant resonances (Ba 4d-->4f, La 4d-->4f, and Nd 4d-->4f transitions) are also reported.

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiLullo, Andrew; Shirato, Nozomi; Cummings, Marvin

Localized spectroscopy with simultaneous topographic, elemental and magnetic information is presented. A synchrotron X-ray scanning tunneling microscope has been employed for the local study of the X-ray magnetic circular dichroism at the FeL 2,3-edges of a thin iron film grown on Cu(111). Polarization-dependent X-ray absorption spectra have been obtained through a tunneling smart tip that serves as a photoelectron detector. In contrast to conventional spin-polarized scanning tunneling microscopy, X-ray excitations provide magnetic contrast even with a non-magnetic tip. Intensity variations in the photoexcited tip current point to chemical variations within a single magnetic Fe domain.

Spectroscopic studies of the binding of Cu(II) complexes of oxicam NSAIDs to alternating G-C and homopolymeric G-C sequences

NASA Astrophysics Data System (ADS)

Chakraborty, Sreeja; Bose, Madhuparna; Sarkar, Munna

2014-03-01

Drugs belonging to the Non-steroidal anti-inflammatory (NSAID) group are not only used as anti-inflammatory, analgesic and anti-pyretic agents, but also show anti-cancer effects. Complexing them with a bioactive metal like copper, show an enhancement in their anti-cancer effects compared to the bare drugs, whose exact mechanism of action is not yet fully understood. For the first time, it was shown by our group that Cu(II)-NSAIDs can directly bind to the DNA backbone. The ability of the copper complexes of NSAIDs namely meloxicam and piroxicam to bind to the DNA backbone could be a possible molecular mechanism behind their enhanced anticancer effects. Elucidating base sequence specific interaction of Cu(II)-NSAIDs to the DNA will provide information on their possible binding sites in the genome sequence. In this work, we present how these complexes respond to differences in structure and hydration pattern of GC rich sequences. For this, binding studies of Cu(II) complexes of piroxicam [Cu(II)-(Px)2 (L)2] and meloxicam [Cu(II)-(Mx)2 (L)] with alternating GC (polydG-dC) and homopolymeric GC (polydG-polydC) sequences were carried out using a combination of spectroscopic techniques that include UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopy. The Cu(II)-NSAIDs show strong binding affinity to both polydG-dC and polydG-polydC. The role reversal of Cu(II)-meloxicam from a strong binder of polydG-dC (Kb = 11.5 × 103 M-1) to a weak binder of polydG-polydC (Kb = 5.02 × 103 M-1), while Cu(II)-piroxicam changes from a strong binder of polydG-polydC (Kb = 8.18 × 103 M-1) to a weak one of polydG-dC (Kb = 2.18 × 103 M-1), point to the sensitivity of these complexes to changes in the backbone structures/hydration. Changes in the profiles of UV absorption band and CD difference spectra, upon complex binding to polynucleotides and the results of competitive binding assay using ethidium bromide (EtBr) fluorescence indicate different binding modes in each case.

Gastrointestinal assimilation of Cu during digestion of a single meal in the freshwater rainbow trout (Oncorhynchus mykiss).

PubMed

Nadella, Sunita R; Bucking, Carol; Grosell, Martin; Wood, Chris M

2006-08-01

Gastrointestinal processing and assimilation of Cu in vivo was investigated by sequential chyme analysis over a 72 h period following ingestion of a single satiation meal (3% body weight) of commercial trout food (Cu content=0.42 micromol g(-1)) by adult rainbow trout. Leaded glass ballotini beads incorporated into the food and detected by X-ray radiography were employed as an inert marker in order to quantify net Cu absorption or secretion in various parts of the tract. Cu concentrations in the supernatant (fluid phase) fell from about 0.06 micromol mL(-1) (63 microM) in the stomach at 2 h to about 0.003 micromol mL(-1) (3 microM) in the posterior intestine at 72 h. Cu concentrations in the solid phase were 10 to 30-fold higher than in the fluid phase, and increased about 4-fold from the stomach at 2 h to the posterior intestine at 72 h. By reference to the inert marker, overall net Cu absorption from the ingested food by 72 h was about 50%. The mid-intestine, and posterior intestine emerged as important sites of net Cu and water absorption and a potential role for the stomach in this process was also indicated. The anterior intestine was a site of large net Cu addition to the chyme, probably due to large net additions of Cu-containing fluids in the form of bile and other secretions in this segment. The results provide valuable information about sites of Cu absorption and realistic concentrations of Cu in chyme fluid for future in vitro mechanistic studies on Cu transport in the trout gastrointestinal tract.

Synthesis and Spectral Evaluation of Some Unsymmetrical Mesoporphyrinic Complexes

PubMed Central

Boscencu, Rica; Oliveira, Anabela Sousa; Ferreira, Diana P.; Ferreira, Luís Filipe Vieira

2012-01-01

Synthesis and spectral evaluation of new zinc and copper unsymmetrical mesoporphyrinic complexes are reported. Zn(II)-5-(4-acetoxy-3-methoxyphenyl)-10,15,20- tris-(4-carboxymethylphenyl)porphyrin, Zn(II)-5-[(3,4-methylenedioxy)phenyl]-10,15,20- tris-(4-carboxymethylphenyl)porphyrin, Cu(II)-5-(4-acetoxy-3-methoxyphenyl)-10,15,20- tris-(4-carboxymethylphenyl)porphyrin and Cu(II)-5-[(3,4-methylenedioxy)phenyl]-10,15,20- tris-(4-carboxymethylphenyl)porphyrin were synthesized using microwave-assisted synthesis. The complexes were characterized by elemental analysis, FT-IR, UV-Vis, EPR and NMR spectroscopy, which fully confirmed their structure. The spectral absorption properties of the porphyrinic complexes were studied in solvents with different polarities. Fluorescence emission and singlet oxygen formation quantum yields were evaluated for the compounds under study, revealing high yields for the zinc derivatives. The copper complexes are not emissive and only display residual capacity for singlet oxygen formation. PMID:22942693

In-vitro study of copper doped SiO{sub 2}-CaO-P{sub 2}O{sub 5} system for bioactivity and antimicrobial properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, Kulwinder; Singh, K. J., E-mail: kanwarjitsingh@yahoo.com; Anand, Vikas

Samples of the xCuO-(45-x)CaO-10P{sub 2}O{sub 5}-45SiO{sub 2} system (x varies from 0 to 4 mole%) have been synthesized for application as biomaterials to slow or inhibit the growth of living organisms (fungi and other pathogenic microorganisms) by the combination of sol-gel and co-precipitation processes. Prepared samples have been characterized by X-Ray Diffraction, Fourier Transform Infra-Red and Field Emission Scanning Electron Microscopy techniques before and after immersion in simulated body fluid. Antimicrobial activity of samples has been investigated against Staphylococcus aureus. Releasing of Cu{sup 2+}and other ions in the simulated body fluid has been determined by Atomic Absorption Spectroscopy to ensuremore » the use of prepared material as biomaterial with good antibacterial properties.« less

[Comparison of heavy metal elements between natural and plantation forests in a subtropical Montane forest].

PubMed

Nie, Ming; Wan, Jia-Rong; Chen, Xiao-Feng; Wang, Li; Li, Bo; Chen, Jia-Kuan

2011-11-01

Heavy metals as one of major pollutants is harmful to the health of forest ecosystems. In the present paper, the concentrations of thirteen heavy metals (Fe, Al, Ti, Cr, Cu, Mn, V, Zn, Ni, Co, Pb, Se and Cd) were compared between natural and plantation forests in the Mt. Lushan by ICP-AES and atomic absorption spectroscopy. The results suggest that the soil of natural forest had higher concentrations of Fe, Al, Ti, Cu, Mn, V, Zn, Ni, Co, Pb, Se, and Cd than the plantation forest except for Cr. The soil of natural forest had a higher level of heavy metals than that of the plantation forest as a whole. This might be due to that the natural forest has longer age than the plantation forest, and fixed soil heavy metals take a longer period of time than the plantation forest.

Antihemolytic activity and mineral contents of Juglans regia L. flowers.

PubMed

Ebrahimzadeh, M A; Nabavi, S F; Nabavi, S M

2013-07-01

Juglans (J.) regia L. is known to possess many biological properties. In this study, antihemolytic activity of methanol extract of Juglans regia L. flower were investigated. Antihemolytic activities of Juglans regia L. flowers were evaluated by various in vitro assays. In addition, scavenging of hydrogen peroxide and mineral contents of flowers were determined using atomic absorption spectroscopy. Extract showed good antihemolytic activity against H2O2 and CuOOH induced hemolysis in comparison with control. Extract was capable of scavenging H2O2 in a concentration dependent manner. IC50 for H2O2 scavenging activity was 311±12.8 µg ml-1. The amount of eight elements was determined and was in the order: Mn > Cu > Fe > Zn. Our study indicate that J. regia flower has remarkable antihemolytic activity, which maybe result of its high phenol and flavonoid contents, especially quercetin.

Step-by-step seeding procedure for preparing HKUST-1 membrane on porous α-alumina support.

PubMed

Nan, Jiangpu; Dong, Xueliang; Wang, Wenjin; Jin, Wanqin; Xu, Nanping

2011-04-19

Metal-organic framework (MOF) membranes have attracted considerable attention because of their striking advantages in small-molecule separation. The preparation of an integrated MOF membrane is still a major challenge. Depositing a uniform seed layer on a support for secondary growth is a main route to obtaining an integrated MOF membrane. A novel seeding method to prepare HKUST-1 (known as Cu(3)(btc)(2)) membranes on porous α-alumina supports is reported. The in situ production of the seed layer was realized in step-by-step fashion via the coordination of H(3)btc and Cu(2+) on an α-alumina support. The formation process of the seed layer was observed by ultraviolet-visible absorption spectroscopy and atomic force microscopy. An integrated HKUST-1 membrane could be synthesized by the secondary hydrothermal growth on the seeded support. The gas permeation performance of the membrane was evaluated. © 2011 American Chemical Society

Thermoelectric Properties of the Chemically Doped Ca3Co4O9 System: A Structural Perspective

NASA Astrophysics Data System (ADS)

Wu, Tao; Tyson, Trevor; Wang, Hsin; Li, Qiang

2010-03-01

Cu doped and Y doped [Ca2CoO3][CoO2]1.61 (referred to as Ca3Co4O9) were prepared by solid state reaction. Temperature dependent thermoelectric properties, resistivity (ρ), Seeback coefficient (S) and thermal conductivity (κ), were measured. As seen before, it is found that doping by Cu and Y significantly enhances the thermoelectric properties. In order to understand the origin of these changes in properties in terms of the atomic structure, synchrotron x-ray diffraction and x-ray absorption spectroscopy were applied to probe the change in the average structure and the location of the dopants. The details of the location and coordination of Co and Y in the host lattice and the effect on the figure of merit are discussed. This work is supported by DOE Grant DE-FG02-07ER46402.

Diketo modification of curcumin affects its interaction with human serum albumin.

PubMed

Shaikh, Shaukat Ali M; Singh, Beena G; Barik, Atanu; Ramani, Modukuri V; Balaji, Neduri V; Subbaraju, Gottumukkala V; Naik, Devidas B; Indira Priyadarsini, K

2018-06-15

Curcumin isoxazole (CI) and Curcumin pyrazole (CP), the diketo modified derivatives of Curcumin (CU) are metabolically more stable and are being explored for pharmacological properties. One of the requirements in such activities is their interaction with circulatory proteins like human serum albumin (HSA). To understand this, the interactions of CI and CP with HSA have been investigated employing absorption and fluorescence spectroscopy and the results are compared with that of CU. The respective binding constants of CP, CI and CU with HSA were estimated to be 9.3×10 5 , 8.4×10 5 and 2.5×10 5 M -1 , which decreased with increasing salt concentration in the medium. The extent of decrease in the binding constant was the highest in CP followed by CI and CU. This revealed that along with hydrophobic interaction other binding modes like electrostatic interactions operate between CP/CI/CU with HSA. Fluorescence quenching studies of HSA with these compounds suggested that both static and dynamic quenching mechanisms operate, where the contribution of static quenching is higher for CP and CI than that for CU. From fluorescence resonance energy transfer studies, the binding site of CU, CI and CP was found to be in domain IIA of HSA. CU was found to bind in closer proximity with Trp214 as compared to CI and CP and the same was responsible for efficient energy transfer and the same was also established by fluorescence anisotropy measurements. Furthermore docking simulation complemented the experimental observation, where both electrostatic as well as hydrophobic interactions were indicated between HSA and CP, CI and CU. This study is useful in designing more stable CU derivatives having suitable binding properties with proteins like HSA. Copyright © 2018 Elsevier B.V. All rights reserved.

Diketo modification of curcumin affects its interaction with human serum albumin

NASA Astrophysics Data System (ADS)

Shaikh, Shaukat Ali M.; Singh, Beena G.; Barik, Atanu; Ramani, Modukuri V.; Balaji, Neduri V.; Subbaraju, Gottumukkala V.; Naik, Devidas B.; Indira Priyadarsini, K.

2018-06-01

Curcumin isoxazole (CI) and Curcumin pyrazole (CP), the diketo modified derivatives of Curcumin (CU) are metabolically more stable and are being explored for pharmacological properties. One of the requirements in such activities is their interaction with circulatory proteins like human serum albumin (HSA). To understand this, the interactions of CI and CP with HSA have been investigated employing absorption and fluorescence spectroscopy and the results are compared with that of CU. The respective binding constants of CP, CI and CU with HSA were estimated to be 9.3 × 105, 8.4 × 105 and 2.5 × 105 M-1, which decreased with increasing salt concentration in the medium. The extent of decrease in the binding constant was the highest in CP followed by CI and CU. This revealed that along with hydrophobic interaction other binding modes like electrostatic interactions operate between CP/CI/CU with HSA. Fluorescence quenching studies of HSA with these compounds suggested that both static and dynamic quenching mechanisms operate, where the contribution of static quenching is higher for CP and CI than that for CU. From fluorescence resonance energy transfer studies, the binding site of CU, CI and CP was found to be in domain IIA of HSA. CU was found to bind in closer proximity with Trp214 as compared to CI and CP and the same was responsible for efficient energy transfer and the same was also established by fluorescence anisotropy measurements. Furthermore docking simulation complemented the experimental observation, where both electrostatic as well as hydrophobic interactions were indicated between HSA and CP, CI and CU. This study is useful in designing more stable CU derivatives having suitable binding properties with proteins like HSA.

Effective charge separation in BiOI/Cu2O composites with enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Xia, Yongmei; He, Zuming; Yang, Wei; Tang, Bin; Lu, Yalin; Hu, Kejun; Su, Jiangbin; Li, Xiaoping

2018-02-01

Novel BiOI/Cu2O composites were designed and synthesized for the first time by coupling reduction method at low temperature. The samples were characterized by XRD, XPS, SEM, EDS, HRTEM, UV-vis (DRS), FTIR and photo-electro-chemical (PEC) analysis. Results showed that the BiOI/Cu2O composites consisted of three-dimensional (3D), hierarchical cauliflower-like structure composed of BiOI nanosheet and Cu2O cubic submicrometer structure, the composite absorption band broadened, and the absorption intensity in the visible region strengthened. And the composites exhibited an excellent photocatalytic performance, which might be attributed to the improvement of the composite absorption and effective charge separation in BiOI/Cu2O composites. In addition, the possible photocatalytic mechanism was proposed.

Biogeochemical spatio-temporal transformation of copper in Aspergillus niger colonies grown on malachite with different inorganic nitrogen sources.

PubMed

Fomina, Marina; Bowen, Andrew D; Charnock, John M; Podgorsky, Valentin S; Gadd, Geoffrey M

2017-03-01

This work elucidates spatio-temporal aspects of the biogeochemical transformation of copper mobilized from malachite (Cu 2 (CO 3 )(OH) 2 ) and bioaccumulated within Aspergillus niger colonies when grown on different inorganic nitrogen sources. It was shown that the use of either ammonium or nitrate determined how copper was distributed within the colony and its microenvironment and the copper oxidation state and succession of copper coordinating ligands within the biomass. Nitrate-grown colonies yielded ∼1.7× more biomass, bioaccumulated ∼7× less copper, excreted ∼1.9× more oxalate and produced ∼1.75× less water-soluble copper in the medium in contrast to ammonium-grown colonies. Microfocus X-ray absorption spectroscopy revealed that as the mycelium matured, bioaccumulated copper was transformed from less stable and more toxic Cu(I) into less toxic Cu(II) which was coordinated predominantly by phosphate/malate ligands. With time, a shift to oxalate coordination of bioaccumulated copper occurred in the central older region of ammonium-grown colonies. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

High performance and thermally stable tandem solar selective absorber coating for concentrated solar thermal power (CSP) application

NASA Astrophysics Data System (ADS)

Prasad, M. Shiva; Kumar, K. K. Phani; Atchuta, S. R.; Sobha, B.; Sakthivel, S.

2018-05-01

A novel tandem absorber system (Mn-Cu-Co-Ox-ZrO2/SiO2) developed on an austenitic stainless steel (SS-304) substrate to show an excellent optical performance (αsol: 0.96; ɛ: 0.23@500 °C). In order to achieve this durable tandem, we experimented with two antireflective layers such as ZrO2-SiO2 and nano SiO2 layer on top of Mn-Cu-Co-Ox-ZrO2 layer. We optimized the thickness of antireflective layers to get good tandem system in terms of solar absorptance and emittance. Field emission scanning electron microscopy (FESEM), UV-Vis-NIR and Fourier transform infrared spectroscopy (FTIR) were used to characterize the developed coatings. Finally, the Mn-Cu-Co-Ox-ZrO2/SiO2 exhibits high temperature resistance up to 800 °C, thus allow an increase in the operating temperature of CSP which may lead to high efficiency. We successfully developed a high temperature resistant tandem layer with easy manufacturability at low cost which is an attractive candidate for concentrated solar power generation (CSP).

A Mott insulator continuously connected to iron pnictide superconductors

DOE PAGES

Song, Yu; Yamani, Zahra; Cao, Chongde; ...

2016-12-19

Iron-based superconductivity develops near an antiferromagnetic order and out of a bad-metal normal state, which has been interpreted as originating from a proximate Mott transition. Whether an actual Mott insulator can be realized in the phase diagram of the iron pnictides remains an open question. Here we use transport, transmission electron microscopy, X-ray absorption spectroscopy, resonant inelastic X-ray scattering and neutron scattering to demonstrate that NaFe 1-xCu xAs near x≈0.5 exhibits real space Fe and Cu ordering, and are antiferromagnetic insulators with the insulating behaviour persisting above the Néel temperature, indicative of a Mott insulator. On decreasing x from 0.5,more » the antiferromagnetic-ordered moment continuously decreases, yielding to superconductivity ~x=0.05. Our discovery of a Mott-insulating state in NaFe 1-xCu xAs thus makes it the only known Fe-based material, in which superconductivity can be smoothly connected to the Mott-insulating state, highlighting the important role of electron correlations in the high-T c superconductivity.« less

Synthesis, characterization, DNA/protein interaction and cytotoxicity studies of Cu(II) and Co(II) complexes derived from dipyridyl triazole ligands

NASA Astrophysics Data System (ADS)

Zhang, Wei; Yao, Di; Wei, Yi; Tang, Jie; Bian, He-Dong; Huang, Fu-Ping; Liang, Hong

2016-06-01

Four different transition metal complexes containing dipyridyl triazole ligands, namely [Cu(abpt)2Cl2]·2H2O (1), [Cu(abpt)2(ClO4)2] (2), [Co2(abpt)2(H2O)2Cl2]·Cl2·4H2O (3) and [Co2(Hbpt)2(CH3OH)2(NO3)2] (4) have been designed, synthesized and further structurally characterized by X-ray crystallography, ESI-MS, elemental analysis, IR and Raman spectroscopy. In these complexes, the both ligands act as bidentate ligands with N, N donors. DNA binding interactions with calf thymus DNA (ct-DNA) of the ligand and its complexes 1 ~ 4 were investigated via electronic absorption, fluorescence quenching, circular dichroism and viscosity measurements as well as confocal Laser Raman spectroscopy. The results show these complexes are able to bind to DNA via the non-covalent mode i.e. intercalation and groove binding or electrostatic interactions. The interactions with bovine serum albumin (BSA) were also studied using UV-Vis and fluorescence spectroscopic methods which indicated that fluorescence quenching of BSA by these compounds was the presence of both static and dynamic quenching. Moreover, the in vitro cytotoxic effects of the complexes against four cell lines SK-OV-3, HL-7702, BEL7404 and NCI-H460 showed the necessity of the coordination action on the biological properties on the respective complex and that all four complexes exhibited substantial cytotoxic activity.

Metal-Ion Distribution and Oxygen Vacancies That Determine the Activity of Magnetically Recoverable Catalysts in Methanol Synthesis.

PubMed

Oracko, Troy; Jaquish, Rigel; Losovyj, Yaroslav B; Morgan, David Gene; Pink, Maren; Stein, Barry D; Doluda, Valentin Yu; Tkachenko, Olga P; Shifrina, Zinaida B; Grigoriev, Maxim E; Sidorov, Alexander I; Sulman, Esther M; Bronstein, Lyudmila M

2017-10-04

Here, we report on the development of novel Zn-, Zn-Cr-, and Zn-Cu-containing catalysts using magnetic silica (Fe 3 O 4 -SiO 2 ) as the support. Transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) showed that the iron oxide nanoparticles are located in mesoporous silica pores and the magnetite (spinel) structure remains virtually unchanged despite the incorporation of Zn and Cr. According to XPS data, the Zn and Cr species are intermixed within the magnetite structure. In the case of the Zn-Cu-containing catalysts, a separate Cu 2 O phase was also observed along with the spinel structure. The catalytic activity of these catalysts was tested in methanol synthesis from syngas (CO + H 2 ). The catalytic experiments showed an improved catalytic performance of Zn- and Zn-Cr-containing magnetic silicas compared to that of the ZnO-SiO 2 catalyst. The best catalytic activity was obtained for the Zn-Cr-containing magnetic catalyst prepared with 1 wt % Zn and Cr each. X-ray absorption spectroscopy demonstrated the presence of oxygen vacancies near Fe and Zn in Zn-containing, and even more in Zn-Cr-containing, magnetic silica (including oxygen vacancies near Cr ions), revealing a correlation between the catalytic properties and oxygen vacancies. The easy magnetic recovery, robust synthetic procedure, and high catalytic activity make these catalysts promising for practical applications.

The Mechanism of Low-Temperature Oxidation of Carbon Monoxide by Oxygen over the PdCl2–CuCl2/γ-Al2O3 Nanocatalyst

PubMed Central

Bruk, Lev; Titov, Denis; Ustyugov, Alexander; Chernikova, Valeriya; Tkachenko, Olga; Kustov, Leonid; Murzin, Vadim; Oshanina, Irina; Temkin, Oleg

2018-01-01

The state of palladium and copper on the surface of the PdCl2–CuCl2/γ-Al2O3 nanocatalyst for the low-temperature oxidation of CO by molecular oxygen was studied by various spectroscopic techniques. Using X-ray absorption spectroscopy (XAS), powder X-ray diffraction (XRD), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), freshly prepared samples of the catalyst were studied. The same samples were also evaluated after interaction with CO, O2, and H2O vapor in various combinations. It was shown that copper exists in the form of Cu2Cl(OH)3 (paratacamite) nanophase on the surface of the catalyst. No palladium-containing crystalline phases were identified. Palladium coordination initially is comprised of four chlorine atoms. It was shown by XAS that this catalyst is not capable of oxidizing CO at room temperature in the absence of H2O and O2 over 12 h. Copper(II) and palladium(II) are reduced to Cu(I) and Pd(I,0) species, respectively, in the presence of CO and H2O vapor (without O2). It was found by DRIFTS that both linear (2114 cm−1, 1990 cm−1) and bridging (1928 cm−1) forms of coordinated CO were formed upon adsorption onto the catalyst surface. Moreover, the formation of CO2 was detected upon the interaction of the coordinated CO with oxygen. The kinetics of CO oxidation was studied at 18–38 °C at an atmospheric pressure for CO, O2, N2, and H2O (gas) mixtures in a flow reactor (steady state conditions). PMID:29614029

Ultrafast carrier dynamics and third-order nonlinear optical properties of AgInS2/ZnS nanocrystals.

PubMed

Yu, Kuai; Yang, Yang; Wang, Junzhong; Tang, Xiaosheng; Xu, Qing-Hua; Wang, Guo Ping

2018-06-22

Broad photoluminescence (PL) emission, a large Stokes shift and extremely long-lived radiative lifetimes are the characteristics of ternary I-III-VI semiconductor nanocrystals (NCs), such as CuInS 2 and AgInS 2 . However, the lack of understanding regarding the intriguing PL mechanisms and photo-carrier dynamics limits their further applications. Here, AgInS 2 and AgInS 2 /ZnS NCs were chemically synthesized and their carrier dynamics were studied by time-resolved PL spectroscopy. The results demonstrated that the surface defect state, which contributed dominantly to the non-radiative decay processes, was effectively passivated through ZnS alloying. Femtosecond transient absorption spectroscopy was also used to investigate the carrier dynamics, revealing the electron storage at the surface state and donor state. Furthermore, the two photon absorption properties of AgInS 2 and AgInS 2 /ZnS NCs were measured using an open-aperture Z-scan technique. The improved third-order nonlinear susceptibility [Formula: see text] of AgInS 2 through ZnS alloying demonstrates potential application in two photon PL biological imaging.

An overview on the research of Sr2IrO4-based system probed by X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Cheng, Jie; Zhu, Chaomin; Ma, Jingyuan; Wang, Yu; Liu, Shengli

2018-03-01

Investigations of materials with 5d transition metal ions have opened up new paradigms in condensed-matter physics because of their large spin-orbit coupling (SOC) interactions. The typical compound is Sr2IrO4, which attracted much attention due to its similarities to the parent compound of high-Tc cuprate superconductor La2CuO4. Theoretical calculations predicted that the unconventional superconductivity can occur in carrier doped-Sr2IrO4 system. Until now, hundreds of experimental methods were devoted to investigate the carrier doping effect on Sr2IrO4. Synchrotron radiation-based X-ray absorption spectroscopy (XAS) made great contributions to the local lattice and electronic structure, and also the intimate relationship between the local structure and physical properties induced by carrier doping. The aim of this review is a short introduction to the progress of research on Sr2IrO4-based system probed by the unique technique — XAS, including the strength of the SOC, valence changes upon doping and even local lattice structure with atomic level for this Sr2IrO4-based family.

Physicochemical and antibacterial characterization of ionocity Ag/Cu powder nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nowak, A., E-mail: ana.maria.nowak@gmail.com; Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów; Szade, J.

Metal ion in bimetallic nanoparticles has shown vast potential in a variety of applications. In this paper we show the results of physical and chemical investigations of powder Ag/Cu nanoparticles obtained by chemical synthesis. Transmission electron microscopy (TEM) experiment indicated the presence of bimetallic nanoparticles in the agglomerated form. The average size of silver and copper nanoparticles is 17.1(4) nm (Ag) and 28.9(2) nm (Cu) basing on the X-ray diffraction (XRD) data. X-ray photoelectron (XPS) and Raman spectroscopies revealed the existence of metallic silver and copper as well as Cu{sub 2}O and CuO being a part of the nanoparticles. Moreover,more » UV–Vis spectroscopy showed surface alloy of Ag and Cu while Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) and Energy Dispersive X-ray Spectroscopy (EDX) showed heterogeneously distributed Ag structures placed on spherical Cu nanoparticles. The tests of antibacterial activity show promising killing/inhibiting growth behaviour for Gram positive and Gram negative bacteria. - Highlights: • Ag/Cu nanoparticles were obtained in the powder form. • The average size of nanoparticles is 17.1(4) nm (Ag) and 28.9(2) nm (Cu). • Ag/Cu powder nanoparticle shows promising antibacterial properties.« less

Adsorption Behavior of TBPS in the Process of Cu Electrodeposition on an Au Film.

PubMed

Chen, Liang-Huei; Liu, Yung-Fang; Krug, Klaus; Lee, Yuh-Lang

2018-05-15

The adsorption behavior of an Cu electroplating additive, 3,3 thiobis-(1-propanesulfonic acid sodium salt) (TBPS) in a process of Cu deposition onto a single crystalline Au(111) surface is studied by an in-situ Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS). The SEIRAS spectra of the TBPS adlayer on a Cu film is investigated first and compared to that on an Au film. These results are utilized to evaluate the characteristics of TBPS adlayer on the electrode surface during the Cu deposition and stripping processes. The results show that the SEIRAS spectra of TBPS adsorbed on the Cu film resembles closely to that on the Au film, and the most pronounced peaks are symmetric S-O (ss-SO) and asymmetric S-O (as-SO) stretching modes. However, the as-SO band is sharper with a higher intensity on the Cu film. Since the ss-SO and as-SO peaks correspond to the molecular with upright and lie-down orientations, respectively, it implies that the TBPS molecules have higher ratio of lie-down orientation on the Cu film. In the Cu electrodeposition process, the cyclic voltammetry (CV) result shows that the presence of the TBPS in the HClO 4 solution can decrease the inhibition effect of HClO 4 to the Cu deposition. For the spectra measured at various potential during cathodic and anodic sweeping, an obvious change of the spectra occurs at ca. 0.6 V, the initiation of Cu underpotential deposition (Cu-UPD). For potentials higher and lower than 0.6 V, the spectra are similar, respectively, to those measured for the Au and Cu films. This result indicates that the TBPS molecules originally adsorbing on the Au film transfer to the surface of deposited Cu layer. This inference is also confirmed by the variation in wavenumber and peak intensity of ss-SO and as-SO peaks during the potential sweeping.

A Chelator-Free Multifunctional [64Cu]-CuS Nanoparticle Platform for Simultaneous Micro-PET/CT Imaging and Photothermal Ablation Therapy

PubMed Central

Zhou, Min; Zhang, Rui; Huang, Miao; Lu, Wei; Song, Shaoli; Melancon, Marites P.; Tian, Mei; Liang, Dong; Li, Chun

2010-01-01

We synthesized and evaluated a novel class of chelator-free [64Cu]-CuS nanoparticles (NPs) suitable for both PET imaging and as photothermal coupling agents for photothermal ablation. [64Cu]-CuS NPs were simple to make, possessed excellent stability, and allowed robust noninvasive micro-PET imaging. Furthermore, CuS NPs displayed strong absorption in the near-infrared (NIR) region (peak 930 nm), passive targeting prefers the tumor site, and mediated ablation of U87 tumor cells upon exposure to NIR light both in vitro and in vivo after either intratumoral or intravenous injection. The combination of small diameter (~11 nm diameter), strong NIR absorption, and integration of 64Cu as a structural component makes [64Cu]-CuS NPs ideally suited for multifunctional molecular imaging and therapy. PMID:20942456

Catalysts at work: From integral to spatially resolved X-ray absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grunwaldt, Jan-Dierk; Kimmerle, Bertram; Baiker, Alfons

2009-09-25

Spectroscopic studies on heterogeneous catalysts have mostly been done in an integral mode. However, in many cases spatial variations in catalyst structure can occur, e.g. during impregnation of pre-shaped particles, during reaction in a catalytic reactor, or in microstructured reactors as the present overview shows. Therefore, spatially resolved molecular information on a microscale is required for a comprehensive understanding of theses systems, partly in ex situ studies, partly under stationary reaction conditions and in some cases even under dynamic reaction conditions. Among the different available techniques, X-ray absorption spectroscopy (XAS) is a well-suited tool for this purpose as the differentmore » selected examples highlight. Two different techniques, scanning and full-field X-ray microscopy/tomography, are described and compared. At first, the tomographic structure of impregnated alumina pellets is presented using full-field transmission microtomography and compared to the results obtained with a scanning X-ray microbeam technique to analyse the catalyst bed inside a catalytic quartz glass reactor. On the other hand, by using XAS in scanning microtomography, the structure and the distribution of Cu(0), Cu(I), Cu(II) species in a Cu/ZnO catalyst loaded in a quartz capillary microreactor could be reconstructed quantitatively on a virtual section through the reactor. An illustrating example for spatially resolved XAS under reaction conditions is the partial oxidation of methane over noble metal-based catalysts. In order to obtain spectroscopic information on the spatial variation of the oxidation state of the catalyst inside the reactor XAS spectra were recorded by scanning with a micro-focussed beam along the catalyst bed. Alternatively, full-field transmission imaging was used to efficiently determine the distribution of the oxidation state of a catalyst inside a reactor under reaction conditions. The new technical approaches together with quantitative data analysis and an appropriate in situ catalytic experiment allowed drawing important conclusions on the reaction mechanism, and the analytical strategy might be similarly applied in other case studies. The corresponding temperature profiles and the catalytic performance were measured by means of an IR-camera and mass spectrometric analysis. In a more advanced experiment the ignition process of the partial oxidation of methane was followed in a spatiotemporal manner which demonstrates that spatially resolved spectroscopic information can even be obtained in the subsecond scale.« less

Phytoremediation of heavy metal copper (Cu2+) by sunflower (Helianthus annuus l.)

NASA Astrophysics Data System (ADS)

Mahardika, G.; Rinanti, A.; Fachrul, M. F.

2018-01-01

A study in microcosmic condition has been carried out to determine the effectiveness of Helianthus annuus as a hyperaccumulator plant for heavy metal, Copper (Cu2+), that exposed in the soil. Artificial pollutants containing Copper (Cu2+) 0, 60, 120, 180 ppm are exposed to uncontaminated soil. The 12-weeks old H. annuus seedling were grown in Cu2+ contaminated soil, with variations of absorption time 3, 6, and 9 weeks. Analysis of Cu2+ concentration on soil and H. annuus (root, stem, leaf) was analised by Atomic Absorbtion Spectrometry (AAS). H. annuus are capable for Cu2+ removal, and the highest removal of Cu2+ is 85.56%, the highest metal accumulation/bioconcentration factor (BCF) is 0.99 occurred at roots with 9 weeks of exposure time and the highest translocation factor (TF) is 0.71. This highest removal is five times better than absorption by stems and leaves. The results concluded, the use of H. annuus for phytoextraction of heavy metals Cu2+ in contaminated soil can be an alternative to the absorption of heavy metal Cu2+ with low concentration metals which is generally very difficult to do in physical-chemical removal.

Pinning down high-performance Cu-chalcogenides as thin-film solar cell absorbers: A successive screening approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yubo; Zhang, Wenqing, E-mail: wqzhang@mail.sic.ac.cn, E-mail: pzhang3@buffalo.edu; State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050

2016-05-21

Photovoltaic performances of Cu-chalcogenides solar cells are strongly correlated with the absorber fundamental properties such as optimal bandgap, desired band alignment with window material, and high photon absorption ability. According to these criteria, we carry out a successive screening for 90 Cu-chalcogenides using efficient theoretical approaches. Besides the well-recognized CuInSe{sub 2} and Cu{sub 2}ZnSnSe{sub 4} materials, several novel candidates are identified to have optimal bandgaps of around 1.0–1.5 eV, spike-like band alignments with CdS window layer, sharp photon absorption edges, and high absorption coefficients. These new systems have great potential to be superior absorbers for photovolatic applications if their carrriermore » transport and defect properties are properly optimized.« less

Efficient Förster resonance energy transfer in 1,2,3-triazole linked BODIPY-Zn(II) meso-tetraphenylporphyrin donor-acceptor arrays.

PubMed

Leonardi, Matthew J; Topka, Michael R; Dinolfo, Peter H

2012-12-17

Cu(I) catalyzed azide-alkyne cycloaddition (CuAAC) reactivity was successfully employed to synthesize three donor-acceptor energy transfer (EnT) arrays that contain one (Dyad), three (Tetrad) and four (Pentad) 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) donors connected to a Zn-tetraphenylporphyrin acceptor via 1,2,3-triazole linkages. The photophysical properties of the three arrays, along with individual donor and acceptor chromophores, were investigated by UV-vis absorption and emission spectroscopy, fluorescence lifetimes, and density functional theory (DFT) electronic structure modeling. Comparison of the UV-vis absorption spectra and frontier molecular orbitals from DFT calculations of the three arrays with ZnTPP, ZnTTrzlP, and Trzl-BODIPY shows that the electronic structure of the chromophores is essentially unperturbed by the 1,2,3-triazole linkage. Time-dependent DFT (TDDFT) calculations on the Dyad reproduce the absorption spectra in THF and show no evidence of excited state mixing of the donor and acceptor. The BODIPY singlet excited state emission is significantly quenched in all three arrays, consistent with EnT to the porphyrin core, with efficiencies of 95.8, 97.5, and 97.2% for the Dyad, Tetrad, and Pentad, respectively. Fluorescence excitation spectra of the three arrays, measured at the porphyrin emission, mirror the absorption profile of both the porphyrin and BODIPY chromophores and are consistent with the Förster resonance energy transfer (FRET) mechanism. Applying Förster theory to the spectroscopic data of the chromophores gives EnT efficiency estimates that are in close agreement with experimental values, suggesting that the through-space mechanism plays a dominant role in the three arrays.

Understanding and control of bipolar self-doping in copper nitride

NASA Astrophysics Data System (ADS)

Fioretti, Angela N.; Schwartz, Craig P.; Vinson, John; Nordlund, Dennis; Prendergast, David; Tamboli, Adele C.; Caskey, Christopher M.; Tuomisto, Filip; Linez, Florence; Christensen, Steven T.; Toberer, Eric S.; Lany, Stephan; Zakutayev, Andriy

2016-05-01

Semiconductor materials that can be doped both n-type and p-type are desirable for diode-based applications and transistor technology. Copper nitride (Cu3N) is a metastable semiconductor with a solar-relevant bandgap that has been reported to exhibit bipolar doping behavior. However, deeper understanding and better control of the mechanism behind this behavior in Cu3N is currently lacking in the literature. In this work, we use combinatorial growth with a temperature gradient to demonstrate both conduction types of phase-pure, sputter-deposited Cu3N thin films. Room temperature Hall effect and Seebeck effect measurements show n-type Cu3N with 1017 electrons/cm3 for low growth temperature (≈35 °C) and p-type with 1015 holes/cm3-1016 holes/cm3 for elevated growth temperatures (50 °C-120 °C). Mobility for both types of Cu3N was ≈0.1 cm2/Vs-1 cm2/Vs. Additionally, temperature-dependent Hall effect measurements indicate that ionized defects are an important scattering mechanism in p-type films. By combining X-ray absorption spectroscopy and first-principles defect theory, we determined that VCu defects form preferentially in p-type Cu3N, while Cui defects form preferentially in n-type Cu3N, suggesting that Cu3N is a compensated semiconductor with conductivity type resulting from a balance between donor and acceptor defects. Based on these theoretical and experimental results, we propose a kinetic defect formation mechanism for bipolar doping in Cu3N that is also supported by positron annihilation experiments. Overall, the results of this work highlight the importance of kinetic processes in the defect physics of metastable materials and provide a framework that can be applied when considering the properties of such materials in general.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Junkuo, E-mail: jkgao@zstu.edu.cn; Wang, Jiangpeng; Qian, Xuefeng

Here we report a novel synthetic pathway for preparation of Cu-doped g-C{sub 3}N{sub 4} (Cu-g-C{sub 3}N{sub 4}) with nanosheet morphology by using a two dimensional Cu–melamine supramolecular network as both sacrificial template and precursor. The specific surface area of Cu-g-C{sub 3}N{sub 4} is 40.86 m{sup 2} g{sup −1}, which is more than 7 times larger than that of pure g-C{sub 3}N{sub 4}. Cu-g-C{sub 3}N{sub 4} showed strong optical absorption in the visible-light region and expanded the absorption to the near-infrared region. The uniform nanosheet morphology, higher surface area and strong visible-light absorption have enabled Cu-g-C{sub 3}N{sub 4} exhibiting enhanced visiblemore » light photocatalytic activity for the photo-degradation of methylene blue (MB). The results indicate that metal–melamine supramolecular network can be promising precursors for the one step preparation of efficient metal-doped g-C{sub 3}N{sub 4} photocatalysts. - Graphical abstract: Cu-doped g-C{sub 3}N{sub 4} (Cu-g-C{sub 3}N{sub 4}) with nanosheet morphology was fabricated via a simple one step preparation by using a two dimensional Cu–melamine supra-molecular network as both sacrificial template and precursor. - Highlights: • Cu-doped g-C{sub 3}N{sub 4} (Cu-g-C{sub 3}N{sub 4}) with nanosheet morphology was prepared. • Cu-g-C{sub 3}N{sub 4} showed strong optical absorption in the visible-light region. • Cu-g-C{sub 3}N{sub 4} exhibits enhanced visible light photocatalytic activity.« less

Bioinspired systems for metal-ion sensing: new emissive peptide probes based on benzo[d]oxazole derivatives and their gold and silica nanoparticles.

PubMed

Oliveira, Elisabete; Genovese, Damiano; Juris, Riccardo; Zaccheroni, Nelsi; Capelo, José Luis; Raposo, M Manuela M; Costa, Susana P G; Prodi, Luca; Lodeiro, Carlos

2011-09-19

Seven new bioinspired chemosensors (2-4 and 7-10) based on fluorescent peptides were synthesized and characterized by elemental analysis, (1)H and (13)C NMR, melting point, matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and IR and UV-vis absorption and emission spectroscopy. The interaction with transition- and post-transition-metal ions (Cu(2+), Ni(2+), Ag(+), Zn(2+), Cd(2+), Hg(2+), Pb(2+), and Fe(3+)) has been explored by absorption and fluorescence emission spectroscopy and MALDI-TOF-MS. The reported fluorescent peptide systems, introducing biological molecules in the skeleton of the probes, enhance their sensitivity and confer them strong potential for applications in biological fields. Gold and silica nanoparticles functionalized with these peptides were also obtained. All nanoparticles were characterized by dynamic light scattering, transmission electron microscopy, and UV-vis absorption and fluorescence spectroscopy. Stable gold nanoparticles (diameter 2-10 nm) bearing ligands 1 and 4 were obtained by common reductive synthesis. Commercial silica nanoparticles were decorated at their surface using compounds 8-10, linked through a silane spacer. The same chemosensors were also taken into aqueous solutions through their dispersion in the outer layer of silica core/poly(ethylene glycol) shell nanoparticles. In both cases, these complex nanoarchitectures behaved as new sensitive materials for Ag(+) and Hg(2+) in water. The possibility of using these species in this solvent is particularly valuable because the impact on human health of heavy- and transition-metal-ion pollution is very severe, and all analytical and diagnostics investigations involve a water environment.

Controlling interfacial properties in supported metal oxide catalysts through metal–organic framework templating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abney, Carter W.; Patterson, Jacob T.; Gilhula, James C.

Precise control over the chemical structure of hard-matter materials is a grand challenge of basic science and a prerequisite for the development of advanced catalyst systems. In this work we report the application of a sacrificial metal-organic framework (MOF) template for the synthesis of a porous supported metal oxide catalyst, demonstrating proof-of-concept for a highly generalizable approach to the preparation new catalyst materials. Application of 2,2’-bipyridine-5,5’-dicarboxylic acid as the organic strut in the Ce MOF precursor results in chelation of Cu 2+ and affords isolation of the metal oxide precursor. Following pyrolysis of the template, homogeneously dispersed CuO nanoparticles aremore » formed in the resulting porous CeO 2 support. By partially substituting non-chelating 1,1’-biphenyl-4,4’-dicarboxylic acid, the Cu 2+ loading and dispersion can be finely tuned, allowing precise control over the CuO/CeO 2 interface in the final catalyst system. Characterization by x-ray diffraction, x-ray absorption fine structure spectroscopy, and in situ IR spectroscopy/mass spectrometry confirm control over interface formation to be a function of template composition, constituting the first report of a MOF template being used to control interfacial properties in a supported metal oxide. Using CO oxidation as a model reaction, the system with the greatest number of interfaces possessed the lowest activation energy and better activity under differential conditions, but required higher temperature for catalytic onset and displayed inferior efficiency at 100 °C than systems with higher Cu-loading. This finding is attributable to greater CO adsorption in the more heavily-loaded systems, and indicates catalyst performance for these supported oxide systems to be a function of at least two parameters: size of adsorption site and extent of interface. In conclusion, optimization of catalyst materials thus requires precise control over synthesis parameters, such as is demonstrated by this MOF-templating method.« less

Electrochemical and Structural Study of a Chemically Dealloyed PtCu Oxygen Reduction Catalyst

PubMed Central

Dutta, Indrajit; Carpenter, Michael K; Balogh, Michael P; Ziegelbauer, Joseph M; Moylan, Thomas E; Atwan, Mohammed H; Irish, Nicholas P

2013-01-01

A carbon-supported, dealloyed platinum-copper (Pt-Cu) oxygen reduction catalyst was prepared using a multi-step synthetic procedure. Material produced at each step was characterized using high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), electron energy loss spectroscopy (EELS) mapping, x-ray absorption spectroscopy (XAS), x-ray diffraction (XRD), and cyclic voltammetry (CV), and its oxygen reduction reaction (ORR) activity was measured by a thin-film rotating disk electrode (TF-RDE) technique. The initial synthetic step, a co-reduction of metal salts, produced a range of poorly crystalline Pt, Cu, and Pt-Cu alloy nanoparticles that nevertheless exhibited good ORR activity. Annealing this material alloyed the metals and increased particle size and crystallinity. TEM shows the annealed catalyst to include particles of various sizes, large (>25 nm), medium (12–25 nm), and small (<12 nm). Most of the small and medium-sized particles exhibited a partial or complete coreshell (Cu-rich core and Pt shell) structure with the smaller particles typically having more complete shells. The appearance of Pt shells after annealing indicates that they are formed by a thermal diffusion mechanism. Although the specific activity of the catalyst material was more than doubled by annealing, the concomitant decrease in Pt surface area resulted in a drop in its mass activity. Subsequent dealloying of the catalyst by acid treatment to partially remove the copper increased the Pt surface area by changing the morphology of the large and some medium particles to a “Swiss cheese” type structure having many voids. The smaller particles retained their core-shell structure. The specific activity of the catalyst material was little reduced by dealloying, but its mass activity was more than doubled due to the increase in surface area. The possible origins of these results are discussed in this report. PMID:23807900

[Determination of Cu in Shell of Preserved Egg by LIBS Coupled with PLS].

PubMed

Hu, Hui-qin; Xu, Xue-hong; Liu, Mu-hua; Tu, Jian-ping; Huang, Le; Huang, Lin; Yao, Ming-yin; Chen, Tian-bing; Yang, Ping

2015-12-01

In this work, the content of copper in the shell of preserved eggs were determined directly by Laser induced breakdown spectroscopy (LIBS), and the characteristics lines of Cu was obtained. The samples of eggshell were pretreated by acid wet digestion, and the real content of Cu was obtained by atomic absorption spectrophotometer (AAS). Due to the test precision and accuracy of LIBS was influenced by a serious of factors, for example, the complex matrix effect of sample, the enviro nment noise, the system noise of the instrument, the stability of laser energy and so on. And the conventional unvariate linear calibration curve between LIBS intensity and content of element of sample, such as by use of Schiebe G-Lomakin equation, can not meet the requirement of quantitative analysis. In account of that, a kind of multivariate calibration method is needed. In this work, the data of LIBS spectra were processed by partial least squares (PLS), the precision and accuracy of PLS model were compared by different smoothing treatment and five pretreatment methods. The result showed that the correlation coefficient and the accuracy of the PLS model were improved, and the root mean square error and the average relative error were reduced effectively by 11 point smoothing with Multiplicative scatter correction (MSC) pretreatment. The results of the study show that, heavy metal Cu in preserved egg shells can be direct detected accurately by laser induced breakdown spectroscopy, and the next step batch tests will been conducted to find out the relationship of heavy metal Cu content in the preserved egg between the eggshell, egg white and egg yolk. And the goal of the contents of heavy metals in the egg white, egg yolk can be knew through determinate the eggshell by the LIBS can be achieved, to provide new method for rapid non-destructive testing technology for quality and satety of agricultural products.

Catalyst-free fabrication of novel ZnO/CuO core-Shell nanowires heterojunction: Controlled growth, structural and optoelectronic properties

NASA Astrophysics Data System (ADS)

Khan, Muhammad Arif; Wahab, Yussof; Muhammad, Rosnita; Tahir, Muhammad; Sakrani, Samsudi

2018-03-01

Development of controlled growth and vertically aligned ZnO/CuO core-shell heterojunction nanowires (NWs) with large area by a catalyst free vapor deposition and oxidation approach has been investigated. Structural characterization reveals successful fabrication of a core ZnO nanowire having single crystalline hexagonal wurtzite structure along [002] direction and CuO nanostructure shell with thickness (8-10 nm) having polycrystalline monoclinic structure. The optical property analysis suggests that the reflectance spectrum of ZnO/CuO heterostructure nanowires is decreased by 18% in the visible range, which correspondingly shows high absorption in this region as compared to pristine ZnO nanowires. The current-voltage (I-V) characteristics of core-shell heterojunction nanowires measured by conductive atomic force microscopy (C-AFM) shows excellent rectifying behavior, which indicates the characteristics of a good p-n junction. The high-resolution transmission electron microscopy (HRTEM) has confirmed the sharp junction interface between the core-shell heterojunction nanowire arrays. The valence band offset and conduction band offset at ZnO/CuO heterointerfaces are measured to be 2.4 ± 0.05 and 0.23 ± 0.005 eV respectively, using X-ray photoelectron spectroscopy (XPS) and a type-II band alignment structure is found. The results of this study contribute to the development of new advanced device heterostructures for solar energy conversion and optoelectronics applications.

Preparation, optical and non-linear optical power limiting properties of Cu, CuNi nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Udayabhaskar, R.; Karthikeyan, B., E-mail: bkarthik@nitt.edu; Ollakkan, Muhamed Shafi

2014-01-06

Metallic nanowires show excellent Plasmon absorption which is tunable based on its aspect ratio and alloying nature. We prepared Cu and CuNi metallic nanowires and studied its optical and nonlinear optical behavior. Optical properties of nanowires are theoretically explained using Gans theory. Nonlinear optical behavior is studied using a single beam open aperture z-scan method with the use of 5 ns Nd: YAG laser. Optical limiting is found to arise from two-photon absorption.

Preparation, optical and non-linear optical power limiting properties of Cu, CuNi nanowires

NASA Astrophysics Data System (ADS)

Udayabhaskar, R.; Ollakkan, Muhamed Shafi; Karthikeyan, B.

2014-01-01

Metallic nanowires show excellent Plasmon absorption which is tunable based on its aspect ratio and alloying nature. We prepared Cu and CuNi metallic nanowires and studied its optical and nonlinear optical behavior. Optical properties of nanowires are theoretically explained using Gans theory. Nonlinear optical behavior is studied using a single beam open aperture z-scan method with the use of 5 ns Nd: YAG laser. Optical limiting is found to arise from two-photon absorption.

Speciation and leaching of trace metal contaminants from e-waste contaminated soils.

PubMed

Cui, Jin-Li; Luo, Chun-Ling; Tang, Chloe Wing-Yee; Chan, Ting-Shan; Li, Xiang-Dong

2017-05-05

Primitive electrical and electronic waste (e-waste) recycling activities have caused serious environmental problems. However, little is known about the speciation and leaching behaviors of metal contaminants at e-waste contaminated sites. This study investigated trace metal speciation/mobilization from e-waste polluted soil through column leaching experiments involving irrigation with rainwater for almost 2.5 years. Over the experimental period, Cu and Zn levels in the porewater were 0.14±0.08mg/L, and 0.16±0.08mg/L, respectively, increasing to 0.33±0.16mg/L, and 0.69±0.28mg/L with plant growth. The amounts of Cu, Zn, and Pb released in surface soil (0-2cm) contributed 43.8%, 22.5%, and 13.8%, respectively, to the original levels. The released Cu and Zn were primarily caused by the mobilization of the carbonate species of metals, including Cu(OH) 2 , CuCO 3 , and Zn 5 (CO 3 ) 2 (OH) 6 , and amorphous Fe/Mn oxides associated fractions characterized by sequential extraction coupling with X-ray absorption spectroscopy. During the experiments, trace metals were not detected in the effluent, and the re-sequestration of trace metals was mainly attributed to the adsorption on the abundant Fe/Mn oxides in the sub-layer soil. This study quantitatively elucidated the molecular speciation of Cu and Zn in e-waste contaminated soil during the column leaching process. Copyright © 2017 Elsevier B.V. All rights reserved.

Detection of stratospheric N2O5 by infrared remote sounding

NASA Technical Reports Server (NTRS)

Toon, G. C.; Farmer, C. B.; Norton, R. H.

1986-01-01

Measurements of N2O5 absorption (1230 and 1260 per cm) in infrared spectra were carried out using the Atmospheric Trace Molecule Spectroscopy (ATMOS) instruments on board Spacelab 3. The detection of stratospheric N2O5, a temporary reservoir species whose photolysis products catalyze ozone destruction, was confirmed. Preliminary analysis of spectra recorded at sunrise on 1 May 1985 indicates a peak volume mixing ratio of 1.6 x 10 the -9th at 35 km an altitude of 35 km, or a broad concentration peak pf 4 x 10 to the 8th molecules per cu cm between 21 and 35 km. Absorption was not detected in spectra measured at sunset due to the depletion of N2O5 by photolysis during the day. The volume mixing ratio profile of N2O5 between 0 and 75 km altitude is reproduced in graphic form.

Multielement extraction system for the determination of 18 trace elements in geochemical samples

USGS Publications Warehouse

Clark, J.R.; Viets, J.G.

1981-01-01

A Methyl isobutyl ketone-Amine synerGistic Iodide Complex (MAGIC) extraction system has been developed for use in geochemical exploration which separates a maximum number of trace elements from interfering matrices. Extraction curves for 18 of these trace elements are presented: Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, Ga, In, Tl, Sa, Pb, As, Sb, Bi, Se, and Te. The acid normality of the aqueous phase controls the extraction into the organic phase, and each of these 18 elements has a broad range of HCl normality over which H is quantitatively extracted, making H possible to determine all 18 trace elements from a single sample digestion or leach solution. The extract can be analyzed directly by flame atomic absorption or inductively coupled plasma emission spectroscopy. Most of these 18 elements can be determined by Nameless atomic absorption after special treatment of the organic extract.

Coaxial carbon plasma gun deposition of amorphous carbon films

NASA Technical Reports Server (NTRS)

Sater, D. M.; Gulino, D. A.; Rutledge, S. K.

1984-01-01

A unique plasma gun employing coaxial carbon electrodes was used in an attempt to deposit thin films of amorphous diamond-like carbon. A number of different structural, compositional, and electrical characterization techniques were used to characterize these films. These included scanning electron microscopy, scanning transmission electron microscopy, X ray diffraction and absorption, spectrographic analysis, energy dispersive spectroscopy, and selected area electron diffraction. Optical absorption and electrical resistivity measurements were also performed. The films were determined to be primarily amorphous, with poor adhesion to fused silica substrates. Many inclusions of particulates were found to be present as well. Analysis of these particulates revealed the presence of trace impurities, such as Fe and Cu, which were also found in the graphite electrode material. The electrodes were the source of these impurities. No evidence of diamond-like crystallite structure was found in any of the film samples. Details of the apparatus, experimental procedure, and film characteristics are presented.

Pulsed laser induced optical nonlinearities in undoped, copper doped and chromium doped CdS quantum dots

NASA Astrophysics Data System (ADS)

Sharma, Dimple; Malik, B. P.; Gaur, Arun

2015-04-01

Quantum dots (QDs) of CdS, Cu doped and Cr doped CdS were synthesized through chemical co- precipitation method. The synthesized QDs have been characterized by x-ray diffraction, ultraviolet visible absorption spectroscopy. The diameters of QDs were calculated using Debye-Scherrer’s formula and Brus equation. They are found to be in 3.5-3.8 nm range. The nonlinear properties has been studied by the open and closed aperture Z-scan technique using frequency double Nd:YAG laser. The nonlinear refractive index (n2), nonlinear absorption coefficient (β), third order nonlinear susceptibilities (χ3) of QDs has been calculated. It has been found that the values of nonlinear parameters are higher for doped QDs than undoped CdS QDs. Hence they can be regarded as potential material for the development of optoelectronics and photonics devices.

Cu/Cu2O nanocomposite films as a p-type modified layer for efficient perovskite solar cells.

PubMed

Chen, You-Jyun; Li, Ming-Hsien; Huang, Jung-Chun-Andrew; Chen, Peter

2018-05-16

Cu/Cu 2 O films grown by ion beam sputtering were used as p-type modified layers to improve the efficiency and stability of perovskite solar cells (PSCs) with an n-i-p heterojunction structure. The ratio of Cu to Cu 2 O in the films can be tuned by the oxygen flow ratio (O 2 /(O 2  + Ar)) during the sputtering of copper. Auger electron spectroscopy was performed to determine the elemental composition and chemical state of Cu in the films. Ultraviolet photoelectron spectroscopy and photoluminescence spectroscopy revealed that the valence band maximum of the p-type Cu/Cu 2 O matches well with the perovskite. The Cu/Cu 2 O film not only acts as a p-type modified layer but also plays the role of an electron blocking buffer layer. By introducing the p-type Cu/Cu 2 O films between the low-mobility hole transport material, spiro-OMeTAD, and the Ag electrode in the PSCs, the device durability and power conversion efficiency (PCE) were effectively improved as compared to the reference devices without the Cu/Cu 2 O interlayer. The enhanced PCE is mainly attributed to the high hole mobility of the p-type Cu/Cu 2 O film. Additionally, the Cu/Cu 2 O film serves as a protective layer against the penetration of humidity and Ag into the perovskite active layer.

Quick-scanning x-ray absorption spectroscopy system with a servo-motor-driven channel-cut monochromator with a temporal resolution of 10 ms.

PubMed

Nonaka, T; Dohmae, K; Araki, T; Hayashi, Y; Hirose, Y; Uruga, T; Yamazaki, H; Mochizuki, T; Tanida, H; Goto, S

2012-08-01

We have developed a quick-scanning x-ray absorption fine structure (QXAFS) system and installed it at the recently constructed synchrotron radiation beamline BL33XU at the SPring-8. Rapid acquisition of high-quality QXAFS data was realized by combining a servo-motor-driven Si channel-cut monochromator with a tapered undulator. Two tandemly aligned monochromators with channel-cut Si(111) and Si(220) crystals covered energy ranges of 4.0-28.2 keV and 6.6-46.0 keV, respectively. The system allows the users to adjust instantly the energy ranges of scans, the starting angles of oscillations, and the frequencies. The channel-cut crystals are cooled with liquid nitrogen to enable them to withstand the high heat load from the undulator radiation. Deformation of the reflecting planes is reduced by clamping each crystal with two cooling blocks. Performance tests at the Cu K-edge demonstrated sufficiently high data quality for x-ray absorption near-edge structure and extended x-ray absorption fine-structure analyses with temporal resolutions of up to 10 and 25 ms, respectively.

TPD IR studies of CO desorption from zeolites CuY and CuX

NASA Astrophysics Data System (ADS)

Datka, Jerzy; Kozyra, Paweł

2005-06-01

The desorption of CO from zeolites CuY and CuX was followed by TPD-IR method. This is a combination of temperature programmed desorption and IR spectroscopy. In this method, the status of activated zeolite (before adsorption), the process of adsorption, and the status of adsorbed molecules can be followed by IR spectroscopy, and the process of desorption (with linear temperature increase) can be followed both by IR spectroscopy and by mass spectrometry. IR spectra have shown two kinds of Cu + sites in both CuY and CuX. Low frequency (l.f.) band (2140 cm -1 in CuY and 2130 cm -1 in CuX) of adsorbed CO represents Cu + sites for which π back donation is stronger and σ donation is weaker whereas high frequency h.f. band (2160 cm -1 in CuY and 2155 cm -1 in CuX) represent Cu + sites for which π back donation is weaker and σ donation is stronger. The TPD-IR experiments evidenced that the Cu + sites represented by l.f. band bond CO more weakly than those represented by h.f. one, indicating that σ donation has more important impact to the strength of Cu +-CO bonding. On the contrary, π back donation has bigger contribution to the activation of adsorbed molecules.

Femtosecond to nanosecond excited state dynamics of vapor deposited copper phthalocyanine thin films.

PubMed

Caplins, Benjamin W; Mullenbach, Tyler K; Holmes, Russell J; Blank, David A

2016-04-28

Vapor deposited thin films of copper phthalocyanine (CuPc) were investigated using transient absorption spectroscopy. Exciton-exciton annihilation dominated the kinetics at high exciton densities. When annihilation was minimized, the observed lifetime was measured to be 8.6 ± 0.6 ns, which is over an order of magnitude longer than previous reports. In comparison with metal free phthalocyanine (H2Pc), the data show evidence that the presence of copper induces an ultrafast relaxation process taking place on the ca. 500 fs timescale. By comparison to recent time-resolved photoemission studies, this is assigned as ultrafast intersystem crossing. As the intersystem crossing occurs ca. 10(4) times faster than lifetime decay, it is likely that triplets are the dominant excitons in vapor deposited CuPc films. The exciton lifetime of CuPc thin films is ca. 35 times longer than H2Pc thin films, while the diffusion lengths reported in the literature are typically quite similar for the two materials. These findings suggest that despite appearing to be similar materials at first glance, CuPc and H2Pc may transport energy in dramatically different ways. This has important implications on the design and mechanistic understanding of devices where phthalocyanines are used as an excitonic material.

Honeycomb-Ordered Na 3Ni 1.5M 0.5BiO 6 (M = Ni, Cu, Mg, Zn) as High-Voltage Layered Cathodes for Sodium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Peng -Fei; Guo, Yu -Jie; Duan, Hui

Developing high-voltage layered cathodes for sodium-ion batteries (SIBs) has always been a severe challenge. Herein, a new family of honeycomb-layered Na 3Ni 1.5M 0.5BiO 6 (M = Ni, Cu, Mg, Zn) with a monoclinic superstructure has been shown to combine good Na + (de)intercalation activity with a competitive 3.3 V high voltage. By coupling the electrochemical process with ex situ X-ray absorption spectroscopy as well as in situ X-ray diffraction, the charge compensation mechanism and structural evolution of these new cathodes are clearly investigated. Interestingly, both Ni 2+/Ni 3+ and Cu 2+/Cu 3+ participate in the redox reaction upon cycling,more » and the succession of single-phase, two-phase, or three-phase regions upon Na+ extraction/insertion were identified with rather good accuracy. Furthermore, this research strategy could provide insights into the structure–function–property relationships on a new series of honeycomb-ordered materials with the general formula Na 3Ni 1.5M 0.5BiO 6 and also serve as a bridge to guide future design of high-performance cathodes for SIBs.« less

Honeycomb-Ordered Na 3Ni 1.5M 0.5BiO 6 (M = Ni, Cu, Mg, Zn) as High-Voltage Layered Cathodes for Sodium-Ion Batteries

DOE PAGES

Wang, Peng -Fei; Guo, Yu -Jie; Duan, Hui; ...

2017-11-01

Developing high-voltage layered cathodes for sodium-ion batteries (SIBs) has always been a severe challenge. Herein, a new family of honeycomb-layered Na 3Ni 1.5M 0.5BiO 6 (M = Ni, Cu, Mg, Zn) with a monoclinic superstructure has been shown to combine good Na + (de)intercalation activity with a competitive 3.3 V high voltage. By coupling the electrochemical process with ex situ X-ray absorption spectroscopy as well as in situ X-ray diffraction, the charge compensation mechanism and structural evolution of these new cathodes are clearly investigated. Interestingly, both Ni 2+/Ni 3+ and Cu 2+/Cu 3+ participate in the redox reaction upon cycling,more » and the succession of single-phase, two-phase, or three-phase regions upon Na+ extraction/insertion were identified with rather good accuracy. Furthermore, this research strategy could provide insights into the structure–function–property relationships on a new series of honeycomb-ordered materials with the general formula Na 3Ni 1.5M 0.5BiO 6 and also serve as a bridge to guide future design of high-performance cathodes for SIBs.« less

To study the effect of calcinations durations and temperature on optical and structural properties of MgO-CuO nanocomposites

NASA Astrophysics Data System (ADS)

Kumar, Rajesh; Praveen, Sharma, Ashwani; Parmar, R.; Dahiya, S.; Kishor, N.

2016-05-01

The MgO-CuO nanocomposites has been synthesized by a sol-gel techniques based on precursor polyvinyl alcohol (PVA). In this work appropriate concentration of cupric nitrate, Magnisium nitrate and PVA are mixed with 50:50 ethanol water followed by heated to 80°C to form a homogeneous gel solution. The obtained gel was slowly heated at 100°C to evaporate the solvent to form a hard homogeneous gel. The hard gel was calcinated at temperature 600°C for 4 hrs and 6 hrs thereafter, crushed the material in agate-motar so that it is converted into fine powder form. The prepared nanocomposites have been characterized using X-Ray Diffraction (XRD), FTIR, UV-VIS spectroscopy, SEM etc. The size of MgO-CuO nanocomposites heated at 600°C for 4 hours and 6 hours evaluated by Debye Scherrer formula are 17.1 nm and 21.2 nm respectively and results show that Size of MgO-CuO nanocomposites increases with increase of calcinations durations. IR spectra is also used to determine purity of samples. Absorption spectra confirm the synthesis of nanomaterials. SEM images give the indication of morphology of the nanocomposites.

Molecular adsorption and multilayer growth of pentacene on Cu(100):Layer structure and energetics

NASA Astrophysics Data System (ADS)

Satta, M.; Iacobucci, S.; Larciprete, R.

2007-04-01

We used the partial charge tight binding method to perform a full structure optimization to determine equilibrium adsorption geometries, energetics, and local charge redistribution for molecular adsorption and multilayer growth of pentacene on Cu(100). We found that single molecule adsorption induces only a localized perturbation of the metal lattice which is limited to the topmost layers. At saturation coverage four stable topologies (Brick, Wave, Lines and Zigzag) were identified, all based on pentacene molecules lying flat on the metal surface and with the central phenyl ring adsorbed in top position. Only two (Brick and Wave) out of the four structures are able to sustain multilayer growth. In both cases, assembling beyond the second layer corresponds to a transition from the flat to a tilted geometry, in which the pentacenes adopt a face-plane-face arrangement leading to a herringbone structure. The energetics of the different structure are reported as a function of the molecular number density of the pentacene multilayer by calculating cohesive, stress, and electrostatic energies. The dominant tilted molecular orientation in the pentacene multilayer is in agreement with the average tilt angle of 65° between the molecular plane and the Cu surface derived by near edge x-ray absorption spectroscopy of a four monolayer pentacene film deposited on Cu(100).

Cu2S-Cu-TiO2 mesoporous carbon composites for the degradation of high concentration of methyl orange under visible light

NASA Astrophysics Data System (ADS)

Zhang, Liang; Zhao, Yuan; Zhong, Lvling; Wang, Yang; Chai, Shouning; Yang, Tao; Han, Xuanli

2017-11-01

A Schiff base compound was used to prepare a Cu2S-Cu-TiO2 mesoporous carbon composite photocatalyst (Cu2S-Cu-TiO2/MC) by a simple precipitation-carbonization method with a carbonization temperature of 750 °C. X-ray diffraction and x-ray photoelectron spectroscopy studies show that Cu2S, Cu, and TiO2 exist in Cu2S-Cu-TiO2/MC in the form of nanometer-sized particles. Scanning electron microscope and transmission electron microscope images show that the composites form a spherical carbon structure inlaid with Cu2S and Cu and coated TiO2. The Brunauer-Emmett-Teller test shows that the material has a large specific surface area (76.14 m2/g) and mesoporous structure. UV-vis diffuse reflection spectroscopy and photoluminescence spectroscopy indicate that the recombination of photo-generated electrons and holes in the samples were inhibited. The composites show good degradation performance in a high concentration (300 mg/L) of methyl orange (MO) solution under visible light. The composites exhibit great potential in the treatment of dyes for wastewater treatment.

Preparation and electromagnetic wave absorption of RGO/Cu nanocomposite

NASA Astrophysics Data System (ADS)

Zhang, Hui; Tian, Xingyou; Zhang, Xian; Li, Shikuo; Shen, Yuhua; Xie, Anjian

2017-09-01

We use a facile pyrolysis method to prepare reduced graphene oxide and copper nanocomposite (RGO/Cu) based on it. The product shows an outstanding wave absorption properties. The maximum reflection loss is up to-50.7 dB at 3.8 GHz. The reflection loss of-10 dB (90% power absorption) corresponds to a bandwidth of 11.2 GHz (3.4-14.6 GHz range) for the layer thickness of 2-5 mm. Therefore, it is suggested that the RGO/Cu nanocomposite is also a new kind of lightweight and high-performance EM wave absorbing material.

Differences in Copper Absorption and Accumulation between Copper-Exclusion and Copper-Enrichment Plants: A Comparison of Structure and Physiological Responses.

PubMed

Fu, Lei; Chen, Chen; Wang, Bin; Zhou, Xishi; Li, Shuhuan; Guo, Pan; Shen, Zhenguo; Wang, Guiping; Chen, Yahua

2015-01-01

Differences in copper (Cu) absorption and transport, physiological responses and structural characteristics between two types of Cu-resistant plants, Oenothera glazioviana (Cu-exclusion type) and Elsholtzia haichowensis (Cu-enrichment type), were investigated in the present study. The results indicated the following: (1) After 50 μM Cu treatment, the Cu ratio in the xylem vessels of E. haichowensis increased by 60%. A Cu adsorption experiment indicated that O. glazioviana exhibited greater resistance to Cu, and Cu absorption and the shoot/root ratio of Cu were significantly lower in O. glazioviana than in E. haichowensis. (2) An analysis of the endogenous abscisic acid (ABA) variance and exogenous ABA treatment demonstrated that the ABA levels of both plants did not differ; exogenous ABA treatment clearly reduced Cu accumulation in both plants. (3) The leaf stomatal density of O. glazioviana was significantly less than that of E. haichowensis. Guard cells in E. haichowensis plants were covered with a thick cuticle layer, the epidermal hair was more numerous and longer, and the number of xylem conduits in the root was small. (4) The transpiration rate and the stomatal conductance of O. glazioviana were both significantly lower than those of E. haichowensis, regardless of whether the plants were treated with Cu. Taken together, these results indicate that the differences in the structural characteristics between these two plant species, particularly in the characteristics related to plant transpiration, are important factors that govern whether plants acquire or exclude Cu.

Cu(II) removal by Anoxybacillus flavithermus-iron oxide composites during the addition of Fe(II)aq

NASA Astrophysics Data System (ADS)

Franzblau, Rachel E.; Daughney, Christopher J.; Swedlund, Peter J.; Weisener, Christopher G.; Moreau, Magali; Johannessen, Bernt; Harmer, Sarah L.

2016-01-01

There is currently poor understanding of metal removal by composites of bacteria and iron oxide minerals, even though they commonly co-occur and are among the most important sorbents in near-surface fluid-rock environments. This study evaluated Cu removal by composites of Anoxybacillus flavithermus and iron oxide over time during the addition, oxidation, and hydrolysis of Fe(II)aq and precipitation of the mineral, in comparison to Cu removal in the two single-sorbent end-member systems. In the absence of iron oxide, Cu removal by A. flavithermus was well described by a previously published surface complexation model, after inclusion of additional reactions describing aqueous complexation by exudate ligands released by the bacteria. In the absence of bacterial cells, Cu removal by iron oxide synthesized in the presence of the bacterial exudate ligands demonstrated the formation of ternary surface complexes. Removal of Cu by the A. flavithermus-iron oxide composites was ca. 20% greater than the prediction based on assumption of additivity in the two end-member systems. This non-additive behavior was attributed to (1) progressive physical blockage of bacterial surface sites by the iron oxide particles, (2) physical blockage of adsorption sites as a result of self-aggregation of the iron oxide particles, and (3) the reduction of Cu(II) to Cu(I) at the bacterial cell surface, as demonstrated by X-ray absorption spectroscopy. The extent of reduction of Cu(II) to Cu(I) was proportional to the concentration of solid phase Fe(II), suggesting that iron oxidation and copper reduction are linked. This study has shown that Cu removal by bacteria-iron oxide composites is greatly affected by redox processes such as Cu(II) reduction on the cell surface both by other bacterial surface ligands and the oxidation of sorbed Fe(II), as well as Fe(II) redox interactions, and aging effects of the mineral (i.e. surface site masking).

Identification of different coordination geometries by XAFS in copper(II) complexes with trimesic acid

NASA Astrophysics Data System (ADS)

Gaur, A.; Klysubun, W.; Soni, Balram; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

2016-10-01

X-ray absorption spectroscopy (XAS) is very useful in revealing the information about geometric and electronic structure of a transition-metal absorber and thus commonly used for determination of metal-ligand coordination. But XAFS analysis becomes difficult if differently coordinated metal centers are present in a system. In the present investigation, existence of distinct coordination geometries around metal centres have been studied by XAFS in a series of trimesic acid Cu(II) complexes. The complexes studied are: Cu3(tma)2(im)6 8H2O (1), Cu3(tma)2(mim)6 17H2O (2), Cu3(tma)2(tmen)3 8.5H2O (3), Cu3(tma) (pmd)3 6H2O (ClO4)3 (4) and Cu3(tma)2 3H2O (5). These complexes have not only Cu metal centres with different coordination but in complexes 1-3, there are multiple coordination geometries present around Cu centres. Using XANES spectra, different coordination geometries present in these complexes have been identified. The variation observed in the pre-edge features and edge features have been correlated with the distortion of the specific coordination environment around Cu centres in the complexes. XANES spectra have been calculated for the distinct metal centres present in the complexes by employing ab-initio calculations. These individual spectra have been used to resolve the spectral contribution of the Cu centres to the particular XANES features exhibited by the experimental spectra of the multinuclear complexes. Also, the variation in the 4p density of states have been calculated for the different Cu centres and then correlated with the features originated from corresponding coordination of Cu. Thus, these spectral features have been successfully utilized to detect the presence of the discrete metal centres in a system. The inferences about the coordination geometry have been supported by EXAFS analysis which has been used to determine the structural parameters for these complexes.

DNA binding and biological studies of some novel water-soluble polymer-copper(II)-phenanthroline complexes.

PubMed

Kumar, Rajendran Senthil; Arunachalam, Sankaralingam; Periasamy, Vaiyapuri Subbarayan; Preethy, Christo Paul; Riyasdeen, Anvarbatcha; Akbarsha, Mohammad Abdulkader

2008-10-01

Some novel water-soluble polymer-copper(II)-phenanthroline complex samples, [Cu(phen)2(BPEI)]Cl(2).4H2O (phen=1,10-phenanthroline, BPEI=branched polyethyleneimine), with different degrees of copper complex content in the polymer chain have been prepared by ligand substitution method in water-ethanol medium and characterized by infrared, UV-visible, EPR spectral and elemental analysis methods. The binding of these complex samples with DNA has been investigated by electronic absorption spectroscopy, emission spectroscopy and gel retardation assay. Electrostatic interactions between DNA molecule and polymer-copper(II) complex molecule containing many high positive charges have been observed. Besides these ionic interactions, van der Waals interactions, hydrogen bonding and other partial intercalation binding modes may also exist in this system. The polymer-copper(II) complex with higher degree of copper complex content was screened for its antimicrobial activity and antitumor activity.

Effect of Electron Beam Irradiation on Structural and Optical Properties of Cu-Doped In2O3 Films Prepared by RF Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Krishnan, R. Reshmi; Sanjeev, Ganesh; Prabhu, Radhakrishna; Pillai, V. P. Mahadevan

2018-02-01

Undoped and Cu-doped In2O3 films were prepared by radiofrequency magnetron sputtering technique. The effects of Cu doping and high-energy electron beam irradiation on the structural and optical properties of as-prepared films were investigated using techniques such as x-ray diffraction, x-ray photoelectron spectroscopy (XPS), lateral scanning electron microscopic image analysis, energy-dispersive x-ray (EDX) spectroscopy, micro-Raman, and ultraviolet-visible (UV-vis) spectroscopy. Moderate doping of Cu in In2O3 enhanced the intensity of (222) peak, indicating alignment of crystalline grains along <111>. Electron beam irradiation promoted orientation of crystalline grains along <111> in undoped and moderately Cu-doped films. EDX spectroscopic and XPS analyses revealed incorporation of Cu2+ ions in the lattice. The transmittance of Cu-doped films decreased with e-beam irradiation. Systematic reduction of the bandgap energy with increase in Cu doping concentration was seen in unirradiated and electron-beam-irradiated films.

Interface architecture determined electrocatalytic activity of Pt on vertically oriented TiO(2) nanotubes.

PubMed

Rettew, Robert E; Allam, Nageh K; Alamgir, Faisal M

2011-02-01

The surface atomic structure and chemical state of Pt is consequential in a variety of surface-intensive devices. Herein we present the direct interrelationship between the growth scheme of Pt films, the resulting atomic and electronic structure of Pt species, and the consequent activity for methanol electro-oxidation in Pt/TiO(2) nanotube hybrid electrodes. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements were performed to relate the observed electrocatalytic activity to the oxidation state and the atomic structure of the deposited Pt species. The atomic structure as well as the oxidation state of the deposited Pt was found to depend on the pretreatment of the TiO(2) nanotube surfaces with electrodeposited Cu. Pt growth through Cu replacement increases Pt dispersion, and a separation of surface Pt atoms beyond a threshold distance from the TiO(2) substrate renders them metallic, rather than cationic. The increased dispersion and the metallic character of Pt results in strongly enhanced electrocatalytic activity toward methanol oxidation. This study points to a general phenomenon whereby the growth scheme and the substrate-to-surface-Pt distance dictates the chemical state of the surface Pt atoms, and thereby, the performance of Pt-based surface-intensive devices.

H2 Production Under Visible Light Irradiation from Aqueous Methanol Solution on CaTiO3:Cu Prepared by Spray Pyrolysis

NASA Astrophysics Data System (ADS)

Lim, Sung Nam; Song, Shin Ae; Jeong, Yong-Cheol; Kang, Hyun Woo; Park, Seung Bin; Kim, Ki Young

2017-10-01

Perovskite-type photocatalysts of CaCu x Ti1- x O3 (0 ≤ x ≤ 0.02) powder were prepared by spray pyrolysis of aqueous solution or aqueous solution with polymeric additive. The effects of the amount of copper ions doped in the photocatalyst and the precursor type on the photocatalytic activity under visible-light irradiation were investigated. The crystal structure, oxidation state, and light adsorption properties of the prepared photocatalysts were analyzed using x-ray diffraction, x-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy, respectively. The doping of copper ions in CaTiO3 allowed visible-light absorption owing to a narrowing of the band gap energy of the host material through the formation of a new donor level for copper ions. Among the doped samples prepared from the aqueous precursor, CaTiO3 doped with 1 mol.% copper ions had the highest hydrogen evolution rate (140.7 μmol g-1 h-1). Notably, the hydrogen evolution rate of the photocatalyst doped with 1 mol.% copper ions prepared from the aqueous precursor with polymeric additive (295.0 μmol g-1 h-1) was two times greater than that prepared from the aqueous precursor, due to the morphology effect.

Low temperature-fired Ni-Cu-Zn ferrite nanoparticles through auto-combustion method for multilayer chip inductor applications

PubMed Central

2012-01-01

Ferrite nanoparticles of basic composition Ni0.7-xZnxCu0.3Fe2O4 (0.0 ≤ x ≤ 0.2, x = 0.05) were synthesized through auto-combustion method and were characterized for structural properties using X-ray diffraction [XRD], scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy [FT-IR]. XRD analysis of the powder samples sintered at 600°C for 4 h showed the cubic spinel structure for ferrites with a narrow size distribution from 28 to 32 nm. FT-IR showed two absorption bands (v1 and v2) that are attributed to the stretching vibration of tetrahedral and octahedral sites. The effect of Zn doping on the electrical properties was studied using dielectric and impedance spectroscopy at room temperature. The dielectric parameters (ε', ε″, tanδ, and σac) show their maximum value for 10% Zn doping. The dielectric constant and loss tangent decrease with increasing frequency of the applied field. The results are explained in the light of dielectric polarization which is similar to the conduction phenomenon. The complex impedance shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume. PACS: 75.50.Gg; 78.20; 77.22.Gm. PMID:22316055

Preparation and characterization of magnetic allylamine modified graphene oxide-poly(vinyl acetate-co-divinylbenzene) nanocomposite for vortex assisted magnetic solid phase extraction of some metal ions.

PubMed

Khan, Mansoor; Yilmaz, Erkan; Sevinc, Basak; Sahmetlioglu, Ertugrul; Shah, Jasmin; Jan, Muhammad Rasul; Soylak, Mustafa

2016-01-01

Magnetic allylamine modified graphene oxide-poly(vinyl acetate-co-divinylbenzene) (MGO-DVB-VA) was synthesized and used for magnetic solid phase extraction of Pb(II), Cd(II), Cu(II), Ni(II) and Co(II) prior to their determination by flame atomic absorption spectroscopy. The adsorbent surface functional group was characterized by using FT-IR and Raman spectroscopy. XRD pattern was used to determine the layers of GO. Surface morphology and elemental composition of the adsorbent were evaluated by using SEM and EDX analysis. Various parameters, effecting adsorption efficiency like initial solution pH, adsorbent dose, type and volume of eluent, volume of sample and diverse ions effects were optimized. The preconcentration factor (PF) is 40 for all the metals and the limits of detection for Pb, Cd, Cu, Ni and Co are in the range of 0.37-2.39 µg L(-1) and relative standard deviation below 3.1%. The method was validated by using the method for certified reference materials (Tobacco Leaves (INCT-OBTL-5), Tomato Leaves (1573a), Certified Water (SPS-ww2) and Certified Water (TMDA 64-2)). The method was successfully applied for natural water and food samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Superconductor to Mott insulator transition in YBa2Cu3O7/LaCaMnO3 heterostructures.

PubMed

Gray, B A; Middey, S; Conti, G; Gray, A X; Kuo, C-T; Kaiser, A M; Ueda, S; Kobayashi, K; Meyers, D; Kareev, M; Tung, I C; Liu, Jian; Fadley, C S; Chakhalian, J; Freeland, J W

2016-09-15

The superconductor-to-insulator transition (SIT) induced by means such as external magnetic fields, disorder or spatial confinement is a vivid illustration of a quantum phase transition dramatically affecting the superconducting order parameter. In pursuit of a new realization of the SIT by interfacial charge transfer, we developed extremely thin superlattices composed of high Tc superconductor YBa2Cu3O7 (YBCO) and colossal magnetoresistance ferromagnet La0.67Ca0.33MnO3 (LCMO). By using linearly polarized resonant X-ray absorption spectroscopy and magnetic circular dichroism, combined with hard X-ray photoelectron spectroscopy, we derived a complete picture of the interfacial carrier doping in cuprate and manganite atomic layers, leading to the transition from superconducting to an unusual Mott insulating state emerging with the increase of LCMO layer thickness. In addition, contrary to the common perception that only transition metal ions may respond to the charge transfer process, we found that charge is also actively compensated by rare-earth and alkaline-earth metal ions of the interface. Such deterministic control of Tc by pure electronic doping without any hindering effects of chemical substitution is another promising route to disentangle the role of disorder on the pseudo-gap and charge density wave phases of underdoped cuprates.

Kinetics and mechanics of photo-polymerized triazole-containing thermosetting composites via the copper(I)-catalyzed azide-alkyne cycloaddition

PubMed Central

Song, Han Byul; Wang, Xiance; Patton, James R.; Stansbury, Jeffrey W.; Bowman, Christopher N.

2017-01-01

Objectives Several features necessary for polymer composite materials in practical applications such as dental restorative materials were investigated in photo-curable CuAAC (copper(I)-catalyzed azide-alkyne cycloaddition) thermosetting resin-based composites with varying filler loadings and compared to a conventional BisGMA/TEGDMA based composite. Methods Tri-functional alkyne and di-functional azide monomers were synthesized for CuAAC resins and incorporated with alkyne-functionalized silica microfillers for CuAAC composites. Polymerization kinetics, in situ temperature change, and shrinkage stress were monitored simultaneously with a tensometer coupled with FTIR spectroscopy and a data-logging thermocouple. The glass transition temperature was analyzed by dynamic mechanical analysis. Flexural modulus/strength and flexural toughness were characterized in three-point bending on a universal testing machine. Results The photo-CuAAC polymerization of composites containing between 0 and 60 wt% microfiller achieved ~99% conversion with a dramatic reduction in the maximum heat of reaction (~20 °C decrease) for the 60 wt% filled CuAAC composites as compared with the unfilled CuAAC resin. CuAAC composites with 60 wt% microfiller generated more than twice lower shrinkage stress of 0.43±0.01 MPa, equivalent flexural modulus of 6.1±0.7 GPa, equivalent flexural strength of 107±9 MPa, and more than 10 times higher energy absorption of 10±1 MJ m−3 when strained to 11% relative to BisGMA-based composites at equivalent filler loadings. Significance Mechanically robust and highly tough, photo-polymerized CuAAC composites with reduced shrinkage stress and a modest reaction exotherm were generated and resulted in essentially complete conversion. PMID:28363645

Kinetics and mechanics of photo-polymerized triazole-containing thermosetting composites via the copper(I)-catalyzed azide-alkyne cycloaddition.

PubMed

Song, Han Byul; Wang, Xiance; Patton, James R; Stansbury, Jeffrey W; Bowman, Christopher N

2017-06-01

Several features necessary for polymer composite materials in practical applications such as dental restorative materials were investigated in photo-curable CuAAC (copper(I)-catalyzed azide-alkyne cycloaddition) thermosetting resin-based composites with varying filler loadings and compared to a conventional BisGMA/TEGDMA based composite. Tri-functional alkyne and di-functional azide monomers were synthesized for CuAAC resins and incorporated with alkyne-functionalized glass microfillers for CuAAC composites. Polymerization kinetics, in situ temperature change, and shrinkage stress were monitored simultaneously with a tensometer coupled with FTIR spectroscopy and a data-logging thermocouple. The glass transition temperature was analyzed by dynamic mechanical analysis. Flexural modulus/strength and flexural toughness were characterized in three-point bending on a universal testing machine. The photo-CuAAC polymerization of composites containing between 0 and 60wt% microfiller achieved ∼99% conversion with a dramatic reduction in the maximum heat of reaction (∼20°C decrease) for the 60wt% filled CuAAC composites as compared with the unfilled CuAAC resin. CuAAC composites with 60wt% microfiller generated more than twice lower shrinkage stress of 0.43±0.01MPa, equivalent flexural modulus of 6.1±0.7GPa, equivalent flexural strength of 107±9MPa, and more than 10 times higher energy absorption of 10±1MJm -3 when strained to 11% relative to BisGMA-based composites at equivalent filler loadings. Mechanically robust and highly tough, photo-polymerized CuAAC composites with reduced shrinkage stress and a modest reaction exotherm were generated and resulted in essentially complete conversion. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Bioavailability enhancement of curcumin by complexation with phosphatidyl choline.

PubMed

Gupta, Nishant Kumar; Dixit, Vinod Kumar

2011-05-01

Curcumin is a major constituent of rhizomes of Curcuma longa. Pharmacokinetic studies of curcumin reveal its poor absorption through intestine. Objective of the present study was to enhance bioavailability of curcumin by its complexation with phosphatidyl choline (PC). Complex of curcumin was prepared with PC and characterized on the basis of solubility, melting point, differential scanning calorimetry, thin layer chromatography, and infrared spectroscopic analysis. Everted intestine sac technique was used to study ex vivo drug absorption of curcumin-PC (CU-PC) complex and plain curcumin. Pharmacokinetic studies were performed in rats, and hepatoprotective activity of CU-PC complex was also compared with curcumin and CU-PC physical mixture in isolated rat hepatocytes. Analytical reports along with spectroscopic data revealed the formation of complex. The results of ex vivo study show that CU-PC complex has significantly increased absorption compared with curcumin, when given in equimolar doses. Complex showed enhanced bioavailability, improved pharmacokinetics, and increased hepatoprotective activity as compared with curcumin or CU-PC physical mixture. Enhanced bioavailability of CU-PC complex may be due to the amphiphilic nature of the complex, which greatly enhance the water and lipid solubility of the curcumin. The present study clearly indicates the superiority of complex over curcumin, in terms of better absorption, enhanced bioavailability, and improved pharmacokinetics. Copyright © 2010 Wiley-Liss, Inc.

Structural and optical properties of CuO in zinc phosphate glasses and effects of gamma irradiation

NASA Astrophysics Data System (ADS)

Ouis, M. A.; ElBatal, H. A.; Abdelghany, A. M.; Hammad, Ahmed H.

2016-01-01

Collective optical and infrared measurements have been employed to investigate the state of increasing copper ions in host 0.5ZnO-0.5P2O5 glass composition. The same spectral measurements were repeated after gamma irradiation with a dose of 20 and 80 KGy. Optical absorption spectra reveal strong UV absorption due to trace ferric ions present as unavoidable impurities within the chemicals used in the preparation of the glasses. Copper containing glasses show an additional broad visible-near infrared band due to distorted octahedrally coordinated Cu2+ ions which at high CuO contents exhibit splitting to several component absorption peaks. Gamma irradiation causes several variations between the response of the base host zinc phosphate glass and effect of increasing CuO. These changes are correlated with both the formation of induced defects through suggested photochemical reactions in the UV region and some shielding effects with increasing CuO in the visible-near infrared spectrum. Infrared absorption spectra reveal repetitive vibrational bands due to phosphate groups mainly from metaphosphate units and the spectra show some variations with the increase of CuO content visualize by the increase of the intensity of the mid broad band extending in the range 800-1500 cm-1.

Reversible inactivation of CO dehydrogenase with thiol compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreß, Oliver; Gnida, Manuel; Pelzmann, Astrid M.

2014-05-09

Highlights: • Rather large thiols (e.g. coenzyme A) can reach the active site of CO dehydrogenase. • CO- and H{sub 2}-oxidizing activity of CO dehydrogenase is inhibited by thiols. • Inhibition by thiols was reversed by CO or upon lowering the thiol concentration. • Thiols coordinate the Cu ion in the [CuSMo(=O)OH] active site as a third ligand. - Abstract: Carbon monoxide dehydrogenase (CO dehydrogenase) from Oligotropha carboxidovorans is a structurally characterized member of the molybdenum hydroxylase enzyme family. It catalyzes the oxidation of CO (CO + H{sub 2}O → CO{sub 2} + 2e{sup −} + 2H{sup +}) which proceedsmore » at a unique [CuSMo(=O)OH] metal cluster. Because of changing activities of CO dehydrogenase, particularly in subcellular fractions, we speculated whether the enzyme would be subject to regulation by thiols (RSH). Here we establish inhibition of CO dehydrogenase by thiols and report the corresponding K{sub i}-values (mM): L-cysteine (5.2), D-cysteine (9.7), N-acetyl-L-cysteine (8.2), D,L-homocysteine (25.8), L-cysteine–glycine (2.0), dithiothreitol (4.1), coenzyme A (8.3), and 2-mercaptoethanol (9.3). Inhibition of the enzyme was reversed by CO or upon lowering the thiol concentration. Electron paramagnetic resonance spectroscopy (EPR) and X-ray absorption spectroscopy (XAS) of thiol-inhibited CO dehydrogenase revealed a bimetallic site in which the RSH coordinates to the Cu-ion as a third ligand ([Mo{sup VI}(=O)OH{sub (2)}SCu{sup I}(SR)S-Cys]) leaving the redox state of the Cu(I) and the Mo(VI) unchanged. Collectively, our findings establish a regulation of CO dehydrogenase activity by thiols in vitro. They also corroborate the hypothesis that CO interacts with the Cu-ion first. The result that thiol compounds much larger than CO can freely travel through the substrate channel leading to the bimetallic cluster challenges previous concepts involving chaperone function and is of importance for an understanding how the sulfuration step in the assembly of the bimetallic cluster might proceed.« less

Effect of fulvic and humic acids on copper and zinc homeostasis in rats.

PubMed

Hullár, István; Vucskits, András Valentin; Berta, Erzsébet; Andrásofszky, Emese; Bersényi, András; Szabó, József

2018-03-01

The objective of this study was to investigate the effects of fulvic acid (FA) and humic acid (HA), the two main compounds of humic substances (HSs), on copper (Cu) and zinc (Zn) homeostasis. Seventy-two male Wistar rats were randomly divided into nine experimental groups. The control diet (AIN-93G formula) and the diets supplemented with 0.1%, 0.2%, 0.4% and 0.8% FA or HA were fed for 26 days. Cu and Zn concentrations of the large intestinal content (LIC), liver, kidney, femur and hair were determined. FA and HA did not influence significantly the Cu or Zn contents of the experimental diets, the rats' feed intake, weight gain and the feed to gain ratio. Both FA and HA decreased the Cu concentrations of the LIC significantly and in a dose-related manner; however the absorption-stimulating effect of HA was more pronounced. FA increased the Cu content of the liver, but neither FA nor HA had a dose-dependent effect on it. FA or HA supplementations had no significant effect on the Cu concentration of the kidney. At the concentrations used, dietary FA or HA supplementations are not promising growth promoters. FA influences the Cu homeostasis unlike HA, because FA not only stimulates Cu absorption, but the extra quantity of absorbed Cu is retained in the organism. The stimulatory effect of HA on Zn absorption may not be manifested in Cu and Zn homeostasis, because of the tight connection of these microelements to FA and HA, which prevents the transmission of Zn from the ZnHA complex to the organs. As regards the effect of FA and HA on Cu and Zn homeostasis, both FA and HA stimulated the absorption of these microelements, but only FA increased the retention of Cu (in the liver) and Zn (in the kidney).

In situ spectroscopic monitoring of CO2 reduction at copper oxide electrode.

PubMed

Wang, Liying; Gupta, Kalyani; Goodall, Josephine B M; Darr, Jawwad A; Holt, Katherine B

2017-04-28

Copper oxide modified electrodes were investigated as a function of applied electrode potential using in situ infrared spectroscopy and ex situ Raman and X-ray photoelectron spectroscopy. In deoxygenated KHCO 3 electrolyte bicarbonate and carbonate species were found to adsorb to the electrode during reduction and the CuO was reduced to Cu(i) or Cu(0) species. Carbonate was incorporated into the structure and the CuO starting material was not regenerated on cycling to positive potentials. In contrast, in CO 2 saturated KHCO 3 solution, surface adsorption of bicarbonate and carbonate was not observed and adsorption of a carbonato-species was observed with in situ infrared spectroscopy. This species is believed to be activated, bent CO 2 . On cycling to negative potentials, larger reduction currents were observed in the presence of CO 2 ; however, less of the charge could be attributed to the reduction of CuO. In the presence of CO 2 CuO underwent reduction to Cu 2 O and potentially Cu, with no incorporation of carbonate. Under these conditions the CuO starting material could be regenerated by cycling to positive potentials.

X-ray absorption investigation of the electronic structure of the CuI@SWCNT nanocomposite

NASA Astrophysics Data System (ADS)

Generalov, A. V.; Brzhezinskaya, M. M.; Vinogradov, A. S.; Püttner, R.; Chernysheva, M. V.; Lukashin, A. V.; Eliseev, A. A.

2011-03-01

The Cu 2 p, I 3 d, and C 1 sX-ray absorption spectra of the CuI@SWCNT nanocomposite prepared by filling single-walled carbon nanotubes (SWCNTs) with the CuI melt by the capillary technique have been measured with a high-energy resolution using the equipment of the Russian-German beamline at the BESSY electron storage ring. In order to characterize the electronic structure of the nanocomposite and possible changes in the atomic and electronic structures of CuI and SWCNTs in the CuI@SWCNT nanocomposite, the spectra obtained have been analyzed in the framework of the quasi-molecular approach by comparing with the spectra of the pristine (CuI and SWCNT) and reference (CuO) systems. It has been revealed that the encapsulation of the CuI compound inside SWCNTs is accompanied by changes in the electronic structure of CuI and SWCNTs due to the chemical interaction between the filler and carbon nanotubes and the change in the atomic structure of CuI.

Synthesis, characterization, DNA/protein interaction and cytotoxicity studies of Cu(II) and Co(II) complexes derived from dipyridyl triazole ligands.

PubMed

Zhang, Wei; Yao, Di; Wei, Yi; Tang, Jie; Bian, He-Dong; Huang, Fu-Ping; Liang, Hong

2016-06-15

Four different transition metal complexes containing dipyridyl triazole ligands, namely [Cu(abpt)2Cl2]·2H2O (1), [Cu(abpt)2(ClO4)2] (2), [Co2(abpt)2(H2O)2Cl2]·Cl2·4H2O (3) and [Co2(Hbpt)2(CH3OH)2(NO3)2] (4) have been designed, synthesized and further structurally characterized by X-ray crystallography, ESI-MS, elemental analysis, IR and Raman spectroscopy. In these complexes, the both ligands act as bidentate ligands with N, N donors. DNA binding interactions with calf thymus DNA (ct-DNA) of the ligand and its complexes 1~4 were investigated via electronic absorption, fluorescence quenching, circular dichroism and viscosity measurements as well as confocal Laser Raman spectroscopy. The results show these complexes are able to bind to DNA via the non-covalent mode i.e. intercalation and groove binding or electrostatic interactions. The interactions with bovine serum albumin (BSA) were also studied using UV-Vis and fluorescence spectroscopic methods which indicated that fluorescence quenching of BSA by these compounds was the presence of both static and dynamic quenching. Moreover, the in vitro cytotoxic effects of the complexes against four cell lines SK-OV-3, HL-7702, BEL7404 and NCI-H460 showed the necessity of the coordination action on the biological properties on the respective complex and that all four complexes exhibited substantial cytotoxic activity. Copyright © 2016. Published by Elsevier B.V.

Synthesis and characterization of copper zinc oxide nanoparticles obtained via metathesis process

NASA Astrophysics Data System (ADS)

Phoohinkong, Weerachon; Foophow, Tita; Pecharapa, Wisanu

2017-09-01

Copper-doped zinc oxide nanoparticles were successfully synthesized by grinding copper acetate and zinc acetate powder with different starting molar ratios in combined with sodium hydroxide. The effect of initial copper and zinc molar ratios on the product samples was investigated and discussed. Relevant ligand coordination type of reactant acetate salt precursors and product samples were investigated by Fourier transform infrared spectroscopy (FTIR). The particle shapes and surface morphologies were characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Phase structures of prepared samples were studied by x-ray powder diffraction (XRD) and x-ray absorption near-edge spectroscopy (XANES) was applied to investigate the local structure of Cu and Zn environment atoms. The results demonstrate that the, particle size of as-synthesized products affected by copper concentration in the precursor trend to gradually decreases from nanorod shape with diameter around 50-100 nm to irregular particle structure around 5 nm associated with an increase in the concentration of copper in precursor. Moreover, it is noticed that shape and morphology of the products are strongly dependent on Cu:Zn ratios during the synthesis. Nanocrystallines Cu-doped ZnO by the substitution in Zn site with a high crystallization degree of hexagonal wurtzite structure were obtained. This synthesis technique is suggested as a potential effective technique for preparing copper zinc oxide nanoparticles with various atomic ratio in wide range of applications. Contribution at the 4th Southeast Asia Conference on Thermoelectrics 2016 (SACT 2016), 15-18 December 2016, Da Nang City, Vietnam.

Biosorption of Copper (II) from Aqueous Solution Using Non-Living Mesorhizobium amorphae Strain CCNWGS0123

PubMed Central

Mohamad, Osama Abdalla; Hao, Xiuli; Xie, Pin; Hatab, Shaimaa; Lin, Yanbing; Wei, Gehong

2012-01-01

The mining industry generates huge amounts of wastewater, containing toxic heavy metals. Treatment to remove heavy metals is necessary and recent work has been focused on finding more environmentally friendly materials for removing heavy metals from wastewater. Biosorption can be an effective process for heavy metal removal from aqueous solutions. Our objectives were to investigate the removal of copper (II) from aqueous solutions using dead cells of Mesorhizobium amorphae CCNWGS0123 under differing levels of pH, agitation speed, temperature, initial copper concentration, biosorbent dose and contact time using flame atomic absorption spectroscopy for metal estimation. The maximum copper removal rate was achieved at pH 5.0, agitation speed 150×g, temperature 28°C and initial Cu (II) concentration of 100 mg L−1. Maximum biosorption capacity was at 0.5 g L−1 and equilibrium was attained within 30 min. Langmuir and Freundlich isotherms showed correlation coefficients of 0.958 and 0.934, respectively. Fourier transform-infrared spectroscopy (FT-IR) analysis indicated that many functional groups, such as O-H, N-H, C-H, C=O, -NH, -CN, C-N, C-O, amide -I, -II, -III and unsaturated alkenes, alkyls and aromatic groups on the cell surface were involved in the interaction between CCNWGS0123 and Cu. Scanning electron microscope and energy dispersive X-ray scanning results showed deformation, aggregation, and cell-surface damage due to the precipitation of copper on the cell surface. Dead cells of CCNWGS0123 showed potential as an efficient biosorbent for the removal of Cu2+ from aqueous solutions. PMID:22353770

Highly luminescent material based on Alq3:Ag nanoparticles.

PubMed

Salah, Numan; Habib, Sami S; Khan, Zishan H

2013-09-01

Tris (8-hydroxyquinoline) aluminum (Alq3) is an organic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes and a host for fluorescent and phosphorescent dyes. In this work thin films of pure and silver (Ag), cupper (Cu), terbium (Tb) doped Alq3 nanoparticles were synthesized using the physical vapor condensation method. They were fabricated on glass substrates and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscopy, atomic force microscope (AFM), UV-visible absorption spectra and studied for their photoluminescence (PL) properties. SEM and AFM results show spherical nanoparticles with size around 70-80 nm. These nanoparticles have almost equal sizes and a homogeneous size distribution. The maximum absorption of Alq3 nanoparticles is observed at 300 nm, while the surface plasmon resonant band of Ag doped sample appears at 450 nm. The PL emission spectra of Tb, Cu and Ag doped Alq3 nanoparticles show a single broad band at around 515 nm, which is similar to that of the pure one, but with enhanced PL intensity. The sample doped with Ag at a concentration ratio of Alq3:Ag = 1:0.8 is found to have the highest PL intensity, which is around 2 times stronger than that of the pure one. This enhancement could be attributed to the surface plasmon resonance of Ag ions that might have increased the absorption and then the quantum yield. These remarkable result suggest that Alq3 nanoparticles incorporated with Ag ions might be quite useful for future nano-optoelectronic devices.

Growth and Characterization of the p-type Semiconductors Tin Sulfide and Bismuth Copper Oxy Selenide

NASA Astrophysics Data System (ADS)

Francis, Jason

BiCuOSe and SnS are layered, moderate band gap (epsilon G ≈ 1 eV) semiconductors that exhibit intrinsic p type conductivity. Doping of BiCuOSe with Ca results in a slight expansion of the lattice and an increase of the hole concentration from 10 18 cm--3 to greater than 1020 cm --3. The large carrier density in undoped films is the result of copper vacancies. Mobility is unaffected by doping, remaining constant at 1.5 cm2V--1s--1 in both undoped and doped films, because the Bi-O layers serve as the source of carriers, while transport occurs within the Cu-Se layers. Bi possesses a 6s2 lone pair that was expected to hybridize with the oxygen p states at the top of the valence band, resulting in high hole mobility as compared to similar materials such as LaCuOSe, which lack this lone pair. However, both LaCuOSe and BiCuOSe have similar hole mobility. X-ray absorption and emission spectroscopy, combined with density functional theory calculations, reveal that the Bi 6 s states contribute deep within the valence band, forming bonding and anti-bonding states with O 2p at 11 eV and 3 eV below the valence band maximum, respectively. Hence, the Bi lone pair does not contribute at the top of the valence band and does not enhance the hole mobility. The Bi 6p states contribute at the bottom of the conduction band, resulting in a smaller band gap for BiCuOSe than LaCuOSe (1 eV vs. 3 eV). SnS is a potential photovoltaic absorber composed of weakly coupled layers stacked along the long axis. This weak coupling results in the formation of strongly oriented films on amorphous substrates. The optical band gap is 1.2 eV, in agreement with GW calculations. Absorption reaches 105 cm--1 within 0.5 eV of the band gap. The p type conduction arises from energetically favorable tin vacancies. Variation of growth conditions yields carrier densities of 1014 -- 1016 cm--3 and hole mobility of 7 -- 15 cm2V--1s--1. SnS was alloyed with rocksalt CaS, which was predicted to form a rocksalt structure when the calcium content is increased past 18%. Films of Sn1--x CaxS with x from 0.4 to 0.9 adopt the rocksalt structure with a band gap of 1.1-1.3 eV, with absorption greater than 105 cm--1 within about 0.7 eV of the band gap. The lattice contracts as the calcium content of the films is increased, reaching 5.7 A when x = 0.93. Films are highly insulating, but Seebeck measurements do indicate p type conduction.

Differences in Copper Absorption and Accumulation between Copper-Exclusion and Copper-Enrichment Plants: A Comparison of Structure and Physiological Responses

PubMed Central

Fu, Lei; Chen, Chen; Wang, Bin; Zhou, Xishi; Li, Shuhuan; Guo, Pan; Shen, Zhenguo; Wang, Guiping; Chen, Yahua

2015-01-01

Differences in copper (Cu) absorption and transport, physiological responses and structural characteristics between two types of Cu-resistant plants, Oenothera glazioviana (Cu-exclusion type) and Elsholtzia haichowensis (Cu-enrichment type), were investigated in the present study. The results indicated the following: (1) After 50 μM Cu treatment, the Cu ratio in the xylem vessels of E. haichowensis increased by 60%. A Cu adsorption experiment indicated that O. glazioviana exhibited greater resistance to Cu, and Cu absorption and the shoot/root ratio of Cu were significantly lower in O. glazioviana than in E. haichowensis. (2) An analysis of the endogenous abscisic acid (ABA) variance and exogenous ABA treatment demonstrated that the ABA levels of both plants did not differ; exogenous ABA treatment clearly reduced Cu accumulation in both plants. (3) The leaf stomatal density of O. glazioviana was significantly less than that of E. haichowensis. Guard cells in E. haichowensis plants were covered with a thick cuticle layer, the epidermal hair was more numerous and longer, and the number of xylem conduits in the root was small. (4) The transpiration rate and the stomatal conductance of O. glazioviana were both significantly lower than those of E. haichowensis, regardless of whether the plants were treated with Cu. Taken together, these results indicate that the differences in the structural characteristics between these two plant species, particularly in the characteristics related to plant transpiration, are important factors that govern whether plants acquire or exclude Cu. PMID:26207743

Compositional ratio effect on the surface characteristics of CuZn thin films

NASA Astrophysics Data System (ADS)

Choi, Ahrom; Park, Juyun; Kang, Yujin; Lee, Seokhee; Kang, Yong-Cheol

2018-05-01

CuZn thin films were fabricated by RF co-sputtering method on p-type Si(100) wafer with various RF powers applied on metallic Cu and Zn targets. This paper aimed to determine the morphological, chemical, and electrical properties of the deposited CuZn thin films by utilizing a surface profiler, atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), UV photoelectron spectroscopy (UPS), and a 4-point probe. The thickness of the thin films was fixed at 200 ± 8 nm and the roughness of the thin films containing Cu was smaller than pure Zn thin films. XRD studies confirmed that the preferred phase changed, and this tendency is dependent on the ratio of Cu to Zn. AES spectra indicate that the obtained thin films consisted of Cu and Zn. The high resolution XPS spectra indicate that as the content of Cu increased, the intensities of Zn2+ decreased. The work function of CuZn thin films increased from 4.87 to 5.36 eV. The conductivity of CuZn alloy thin films was higher than pure metallic thin films.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yue Ru; Poyraz, Altug S.; Hu, Xiaobing

Birnessite type layered manganese dioxides (δ-MnO 2) have attracted considerable attention in recent years as 2D intercalation cathodes for rechargeable Li +, Na +, and Mg 2+ batteries due to fast ion diffusion through their negatively charged δ-MnO 2 sheets separated by interlayer cations and a stable Mn 3+/4+ redox couple. Here we report the preparation and electrochemistry of zero and divalent copper co-intercalated birnessite type manganese dioxide (Cu 0 0.03Cu 2+ 0.21Na 0.12MnO 2·0.9H 2O). The copper intercalated birnessite materials were fully characterized utilizing powder X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM).more » The mixed valent nature of intercalated Cu 0 and Cu 2+ was confirmed by X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). Electrochemical evaluation results show that zero valent copper intercalated birnessite exhibits higher discharge capability, improved cyclability, and lower impedance compared to the Cu 2+ only intercalated (Cu 0.26MnO 2·1.0H 2O) and Cu free Na birnessite (Na 0.40MnO 2·1.0H 2O) materials. Remarkably, zero valent copper birnessite shows almost no fade after 10 cycles at 0.1 mV/s. Electrochemical impedance spectroscopy results suggest that charge transfer resistivity of Cu 0 modified samples was much lower than that of Cu 2+ and Cu free birnessite, indicating that the presence of a small amount of Cu 0 improves the conductivity of birnessite and results in better electrochemical cyclability, rate capability, and lower impedance.« less

Depth Profile of Induced Magnetic Polarization in Cu Layers of Co/Cu(111) Metallic Superlattices by Resonant X-ray Magnetic Scattering at the Cu K Absorption Edge

NASA Astrophysics Data System (ADS)

Uegaki, Shin; Yoshida, Akihiro; Hosoito, Nobuyoshi

2015-03-01

We investigated induced spin polarization of 4p conduction electrons in Cu layers of antiferromagnetically (AFM) and ferromagnetically (FM) coupled Co/Cu(111) metallic superlattices by resonant X-ray magnetic scattering at the Cu K absorption edge. Magnetic reflectivity profiles of the two superlattices were measured in the magnetic saturation state with circularly polarized synchrotron radiation X-rays at 8985 eV. Depth profiles of the resonant magnetic scattering length of Cu, which corresponds to the induced spin polarization of Cu, were evaluated in the two Co/Cu superlattices by analyzing the observed magnetic reflectivity profiles. We demonstrated that the spin polarization induced in the Cu layer was distributed around the Co/Cu interfaces with an attenuation length of several Å in both AFM and FM coupled superlattices. The uniform component, which exists in Au layers of Fe/Au(001) superlattices, was not found in the depth distribution of induced magnetic polarization in the Cu layers of Co/Cu(111) superlattices.

The mapping and differentiation of biological and environmental elemental signatures in the fossil remains of a 50 million year old bird

DOE Office of Scientific and Technical Information (OSTI.GOV)

Egerton, Victoria M.; Wogelius, Roy A.; Norell, Mark A.

The preservation of fossils reflects the interplay of inorganic and organic chemical processes, which should be clearly differentiated to make interpretations about the biology of extinct organisms. A new coliiformes bird (mouse bird) from the ~50 million year old Green River Formation (Wyoming, USA) has here been analysed using synchrotron X-ray fluorescence and environmental scanning electron microscopy with an attached X-ray energy dispersive system (ESEM-EDS). The concentration and distribution of 16 elements (Si, P, S, Cl, K, Ca, Ti, Mg, Fe, Ni, Cu, Zn, As, Br, Ba, Hg) has been mapped for individual points on the sample. S, Cu andmore » Zn map distinctly within visibly preserved feathers and X-ray Absorption Spectroscopy (XAS) shows that S and Cu within the feathers are organically bound in a similar manner to modern feathers. The morphological preservation of the feathers, on both macro- and microscopic scales, is variable throughout the fossil and the differences in the lateral microfacies have resulted in a morphological preservation gradient. This study clearly differentiates endogenous organic remains from those representing exogenous overprinted geochemical precipitates and illustrates the chemical complexity of the overall taphonomic process.« less

The mapping and differentiation of biological and environmental elemental signatures in the fossil remains of a 50 million year old bird

DOE PAGES

Egerton, Victoria M.; Wogelius, Roy A.; Norell, Mark A.; ...

2015-01-22

The preservation of fossils reflects the interplay of inorganic and organic chemical processes, which should be clearly differentiated to make interpretations about the biology of extinct organisms. A new coliiformes bird (mouse bird) from the ~50 million year old Green River Formation (Wyoming, USA) has here been analysed using synchrotron X-ray fluorescence and environmental scanning electron microscopy with an attached X-ray energy dispersive system (ESEM-EDS). The concentration and distribution of 16 elements (Si, P, S, Cl, K, Ca, Ti, Mg, Fe, Ni, Cu, Zn, As, Br, Ba, Hg) has been mapped for individual points on the sample. S, Cu andmore » Zn map distinctly within visibly preserved feathers and X-ray Absorption Spectroscopy (XAS) shows that S and Cu within the feathers are organically bound in a similar manner to modern feathers. The morphological preservation of the feathers, on both macro- and microscopic scales, is variable throughout the fossil and the differences in the lateral microfacies have resulted in a morphological preservation gradient. This study clearly differentiates endogenous organic remains from those representing exogenous overprinted geochemical precipitates and illustrates the chemical complexity of the overall taphonomic process.« less

DSC and optical studies on BaO-Li{sub 2}O-B{sub 2}O{sub 3}-CuO glass system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhogi, Ashok, E-mail: ashokbhogi@gmail.com; Kumar, R. Vijaya; Ahmmad, Shaik Kareem

2016-05-06

Glasses with composition 15BaO-25Li{sub 2}O-(60-x)B{sub 2}O{sub 3} -xCuO (x= 0, 0.2, 0.4, 0.6, 0.8 and 1 mol%) were prepared by the conventional melt quenching technique. These glasses were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and density measurements. Optical absorption studies were carried out as a function of copper ion concentration. The optical absorption spectra of studied glasses containing copper oxide exhibit a single broad band around 761nm which has been assigned to the 2B{sub 1g}→2B{sub 2g} transition. From these studies, the variations in the values of glass transition temperature (T{sub g}) have been observed. The fundamental absorption edgemore » has been determined from the optical absorption spectra. The values of optical band gap and Urbach energy were determined with increase in concentration of CuO. The variations in density, glass transition temperature, optical band gap and Urbach energy with CuO content have been discussed in terms of changes in the glass structure. The analysis of these results indicated that copper ions mostly exist in Cu{sup 2+} state in these glasses when the concentration of CuO ≤ 0.8 mol% and above this concentration copper ions seem to subsist in Cu{sup 1+} state.« less

Origin of electrically heterogeneous microstructure in CuO from scanning tunneling spectroscopy study

NASA Astrophysics Data System (ADS)

Sarkar, Sudipta; Jana, Pradip Kumar; Chaudhuri, B. K.

2008-04-01

We report electronic structure of the grains and grain boundaries (GBs) of the high permittivity (κ˜104) ceramic CuO from scanning tunneling spectroscopy (STS) studies. The p-type semiconducting character of the CuO grains and insulating behavior of the corresponding GBs, observed from STS studies, have been explained. This type of electrically inhomogeneous microstructure leads to the formation of barrier layer capacitance elements in CuO and, hence, provides an explanation of the colossal-κ response exhibited by CuO.

A phenolic acid based colourimetric 'naked-eye' chemosensor for the rapid detection of Cu(II) ions

NASA Astrophysics Data System (ADS)

Sengupta, Priti; Ganguly, Aniruddha; Bose, Adity

2018-06-01

The crucial role of chemosensor for the immediate recognition of environment pollutant motivates the researchers to develop variety of sensing protocols. Of various chemosensory protocols, the colour change observed by the naked eye is considered to be a conceivable and on-site way to indicate the presence of an analyte. We herein report a colourimetric and commercially available absorption probe, sinapic acid (SA) that is completely ready to use for "on-site" visual determination of copper ions. The molecule, SA is well-known phenolic acid, often utilized for its antibacterial activity. In this work, for the first time, we are exploring its ability to work as an efficient Cu2+ sensor. This sensor molecule selectively detected Cu2+ ions by changing its colour from colourless to pink within detection limit of 64.5 nM, which is much lower than other reported sensor molecules and the suggested limit by World Health Organization (WHO) and U. S. Environmental Protection Agency (EPA) guidelines. The sensing mechanism was investigated through UV-vis and 1H NMR titration along with ESI-MS spectroscopy and further confirmed by DFT computational studies. Studies revealed the participation of hydroxyl group (sbnd OH) and methoxy group (sbnd OMe) of SA in complexation with Cu2+. The binding stoichiometry of SA to Cu2+ was found to be 1:2 through Job's plot and ESI-MS analysis. Importantly, paper strips of SA were prepared which could be used for a rapid "on-site" determination of Cu2+ containing samples.

Reduction of chromium (VI) on the hetero-system CuBi2O4/TiO2 under solar light

NASA Astrophysics Data System (ADS)

Lahmar, H.; Benamira, M.; Akika, F. Z.; Trari, M.

2017-11-01

The CuBi2O4/TiO2 heterojunction was tested with success for the photo-catalytic reduction of chromate ions under sunlight. CuBi2O4, prepared by nitrate process, was characterised photo-electrochemically. The oxide is stable against photo corrosion by consumption of holes in presence of oxalic acid. The light absorption promotes electrons in the conduction band of the sensitizer (CuBi2O4) with a very negative potential (-1.74 VSCE) to participate in the exchange of the electron with HCrO4-. The enhanced activity is due to electron injection of activated CuBi2O4 into TiO2-CB (-0.97 VSCE). The band gap of the semiconductor CuBi2O4 is 1.50 eV with a direct optical transition. This compound is a p-type semiconductor with a flat band potential of -0.39 VSCE and activation energy of 0.18 eV. The electrochemical impedance spectroscopy was undertaken to study the semiconductor/electrolyte interfacial phenomena. The photoactivity on the heterojunction is strongly enhanced. A remarkable performance is obtained in less than 4 h for a concentration of 30 mg in (Cr (VI)) at pH ∼ 4 and a dose of 1 mg/mL; a 98% reduction has been obtained. The kinetic of chromate photoreduction is well described by the Langmuir-Hinshelwood model. The chromate elimination obeys to a pseudo-first order kinetic with an apparent rate constant of 0.014 min-1.

Preparation and characterization of zinc and copper co-doped WO3 nanoparticles: Application in photocatalysis and photobiology.

PubMed

Mohammadi, Sanaz; Sohrabi, Maryam; Golikand, Ahmad Nozad; Fakhri, Ali

2016-08-01

In this study, pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles samples were prepared by precipitation and co-precipitation methods. These nanoparticles were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDX), Dynamic light scattering (DLS), UV-visible and photoluminescence (PL) spectroscopy. The synthesized pure, Zn, Cu, Zn,Cu co-doped WO3 nanoparticles have smart optical properties and average sizes with 3.2, 3.12, 3.08 and 2.97eV of band-gap, 18.1, 23.2, 25.7 and 30.2nm, respectively. Photocatalytic activity of four nanoparticles was studying towards degradation of gentamicin antibiotic under ultraviolet and visible light irradiation. The result showed that Zn,Cu co-doped WO3 possessed high photocatalytic activity. The photocatalytic activity of WO3 nanoparticles could be remarkably increased by doping the Zn and Cu impurity. This can be attributed to the fact that the red shift of absorption edge and the trapping effect of the mono and co-doped WO3 nanoparticles. The research result presents a general and effective way to prepare different photocatalysts with enhanced visible and UV light-driven photocatalytic performance. Antibacterial activity of four different WO3 nanoparticles against Escherichia coli bacterium has been assessed by the agar disc method under light irradiation and dark medium. It is concluded from the present findings that WO3 nanoparticles can be used as an efficient antibacterial agent. Copyright © 2016 Elsevier B.V. All rights reserved.

Assessment of waste oyster shells and coal mine drainage sludge for the stabilization of As-, Pb-, and Cu-contaminated soil.

PubMed

Moon, Deok Hyun; Cheong, Kyung Hoon; Koutsospyros, Agamemnon; Chang, Yoon-Young; Hyun, Seunghun; Ok, Yong Sik; Park, Jeong-Hun

2016-02-01

A novel treatment mix was designed for the simultaneous immobilization of As, Cu, and Pb in contaminated soils using natural (waste oyster shells (WOS)) and industrial (coal mine drainage sludge (CMDS)) waste materials. The treatments were conducted using the standard U.S. sieve size no. 20 (0.85 mm) calcined oyster shells (COS) and CMDS materials with a curing time of 1 and 28 days. The As immobilization treatments were evaluated using the 1-N HCl extraction fluid, whereas the Pb and Cu immobilization treatments were evaluated using the 0.1-N HCl extraction fluid based on the Korean leaching standards. The treatment results showed that the immobilization of As, Cu, and Pb was best achieved using a combination mix of 10 wt% COS and 10 wt% CMDS. This treatment mix was highly effective leading to superior leachability reductions for all three target contaminants (>93 % for As and >99 % for Cu and Pb) for a curing period of 28 days. The X-ray absorption near-edge structure (XANES) results showed that As was present in the form of As(V) in the control sample and that no changes in As speciation were observed following the COS-CMDS treatments. The scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX) sample treated with 10 wt% COS and 10 wt% CMDS indicated that As immobilization may be associated with the formation of Ca-As and Fe-As precipitates while Pb and Cu immobilization was most probably linked to calcium silicate hydrates (CSHs) and calcium aluminum hydrates (CAHs).

Design of binary SnO{sub 2}-CuO nanocomposite for efficient photocatalytic degradation of malachite green dye

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Aniket; Rout, Lipeeka; Achary, L. Satish Kumar

2016-04-13

Semiconductor mediated photocatalysis has got enormous consideration as it has shown immense potential in addressing the overall energy and environmental issues. To overcome the earlier drawbacks concerning quick charge recombination and limited visible-light absorption of semiconductor photocatalysts, numerous methods have been produced in the past couple of decades and the most broadly utilized one is to develop the photocatalytic heterojunctions. In our work, a series of SnO{sub 2}-CuO nanocomposites of different compositions were synthesized by a combustion method and have been investigated in detail by various characterization techniques, such as wide angle X-ray diffraction (XRD), UV-vis spectroscopy, transmission electron microscopymore » (TEM), and field emission scanning electron microscopy (FE-SEM). The results revealed that the crystal structure and optical properties of the nanocomposites were almost same for all the compositions. FE-SEM images showed that the shape of SnO{sub 2}-CuO was spherical in nature and the 1: 1 Sn/Cu sample had a well-proportioned morphology. The malachite green dye was used for the photocatalytic studies in a photoreactor and monitored with a UV-visible spectrometer for different composition ratio of metal (Sn: Cu) such as 1:1, 1:2, 2:1, 1:0.5 and 0.5:1. The 1:1 ratio nanocomposite showed excellent photocatalytic degradation of 96 % compared to pure SnO{sub 2} and CuO. The mechanism of degradation and charge separation ability of the nanocomposite are also explored using photocurrent measurement study.« less

A phenolic acid based colourimetric 'naked-eye' chemosensor for the rapid detection of Cu(II) ions.

PubMed

Sengupta, Priti; Ganguly, Aniruddha; Bose, Adity

2018-06-05

The crucial role of chemosensor for the immediate recognition of environment pollutant motivates the researchers to develop variety of sensing protocols. Of various chemosensory protocols, the colour change observed by the naked eye is considered to be a conceivable and on-site way to indicate the presence of an analyte. We herein report a colourimetric and commercially available absorption probe, sinapic acid (SA) that is completely ready to use for "on-site" visual determination of copper ions. The molecule, SA is well-known phenolic acid, often utilized for its antibacterial activity. In this work, for the first time, we are exploring its ability to work as an efficient Cu 2+ sensor. This sensor molecule selectively detected Cu 2+ ions by changing its colour from colourless to pink within detection limit of 64.5nM, which is much lower than other reported sensor molecules and the suggested limit by World Health Organization (WHO) and U. S. Environmental Protection Agency (EPA) guidelines. The sensing mechanism was investigated through UV-vis and 1 H NMR titration along with ESI-MS spectroscopy and further confirmed by DFT computational studies. Studies revealed the participation of hydroxyl group (OH) and methoxy group (OMe) of SA in complexation with Cu 2+ . The binding stoichiometry of SA to Cu 2+ was found to be 1:2 through Job's plot and ESI-MS analysis. Importantly, paper strips of SA were prepared which could be used for a rapid "on-site" determination of Cu 2+ containing samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Distinguishing polymorphs of the semiconducting pigment copper phthalocyanine by solid-state NMR and Raman spectroscopy.

PubMed

Shaibat, Medhat A; Casabianca, Leah B; Siberio-Pérez, Diana Y; Matzger, Adam J; Ishii, Yoshitaka

2010-04-08

Cu(II)(phthalocyanine) (CuPc) is broadly utilized as an archetypal molecular semiconductor and is the most widely used blue printing pigment. CuPc crystallizes in six different forms; the chemical and physical properties are substantially modulated by its molecular packing among these polymorphs. Despite the growing importance of this system, spectroscopic identification of different polymorphs for CuPc has posed difficulties. This study presents the first example of spectroscopic distinction of alpha- and beta-forms of CuPc, the most widely used polymorphs, by solid-state NMR (SSNMR) and Raman spectroscopy. (13)C high-resolution SSNMR spectra of alpha- and beta-CuPc using very-fast magic angle spinning (VFMAS) at 20 kHz show that hyperfine shifts sensitively reflect polymorphs of CuPc. The experimental results were confirmed by ab initio chemical shift calculations. (13)C and (1)H SSNMR relaxation times of alpha- and beta-CuPc under VFMAS also showed marked differences, presumably because of the difference in electronic spin correlation times in the two forms. Raman spectroscopy also provided another reliable method of differentiation between the two polymorphs.

Application of glucose as a green capping agent and reductant to fabricate CuI micro/nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tavakoli, Farnosh; Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir; Ghanbari, Davood

Graphical abstract: - Highlights: • CuI nanostructures were prepared via a simple precipitation method. • Glucose as a green capping agent and reductant was applied. • The effect of glucose concentration on the morphology of CuI was investigated. • According to XRD results, pure cubic phase CuI have been formed by using glucose. - Abstract: In this work, CuI micro/nanostructures have been successfully prepared via a simple precipitation route at room temperature. By using glucose as a clean reducing agent with different concentrations, CuI micro/nanostructures with various morphologies were obtained. Besides glucose, Na{sub 2}SO{sub 3}, KBH{sub 4} and N{sub 2}H{submore » 4}·H{sub 2}O have been applied as reductant. X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectroscopy, X-ray energy dispersive spectroscopy (EDS) and Fourier transformed infrared (FT-IR) spectroscopy were used to characterize the as-produced CuI micro/nanostructures. According to the XRD results, it was found that pure cubic phase CuI have been formed by using glucose.« less

Air pollution assessment of Salé's city (Morocco)

NASA Astrophysics Data System (ADS)

Bounakhla, M.; Fatah, A.; Embarch, K.; Ibn Majah, M.; Azami, R.; Sabir, A.; Nejjar, A.; Cherkaoui, R.; Gaudry, A.

2003-05-01

Four sites were selected in Sale's city in Morocco in order to contribute in air pollution level assessment and determination of its effects on public health. The sites were selected so that they are close to the most important industrialized areas, they have a very high demographic density and they cover a heavy traffic. Two approaches of air sampling and subsequent analysis methods of elements in atmospheric aerosols have been performed. The first is a classical approach, which consists in sampling total airborne materials with a High Volume Sampler and analysing the samples using Atomic Absorption Spectroscopy (AAS). The second is having its interest for studies relating effects of particles on human health. It consists in employing a Dichotomous Sampler to collect inhalable particles and the X-ray Fluorescence (XRF) for elemental analysis. With such system, it was possible to collect separately respirable and inhalable aerosols. The ED-XRF analysis method used is appropriate for monitoring airborne polluants in living and working areas with advantage of simple preparation, nondestructive nature, rapidity and suitable limits of detection. Using this method, it was possible to identify and quantify S, Ca, CI, Fe, Cu, and Pb. With Atomic Absorption Spectroscopy Analysis Method, we quantified Cd. This study have been completed by measuring NOx SO2 and solid suspended particles or airborne particulate matter (APM).

EPR and optical absorption study of Cu{sup 2+} doped lithium sulphate monohydrate (LSMH) single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheela, K. Juliet; Subramanian, P., E-mail: psubramaniangri@gmail.com; Krishnan, S. Radha

2016-05-23

EPR study of Cu{sup 2+} doped NLO active Lithium Sulphate monohydrate (Li{sub 2}SO{sub 4.}H{sub 2}O) single crystals were grown successfully by slow evaporation method at room temperature. The principal values of g and A tensors indicate existence of orthorhombic symmetry around the Cu{sup 2+} ion. From the direction cosines of g and A tensors, the locations of Cu{sup 2+} in the lattice have been identified as interstitial site. Optical absorption confirms the rhombic symmetry and ground state wave function of the Cu{sup 2+} ion in a lattice as d{sub x2-y2}.

On the transformation behaviour, mechanical properties and biocompatibility of two niti-based shape memory alloys: NiTi42 and NiTi42Cu7.

PubMed

Es-Souni, M; Es-Souni, M; Brandies, H F

2001-08-01

The transformation behaviour, mechanical properties and cytotoxicity of a binary NiTi42 and a ternary NiTi42Cu7 alloy have been investigated. The transformation temperatures were determined via differential scanning calorimetry, the mechanical properties have been investigated in 3-point bending tests in the temperature range between 6 and 60 degrees C. The cytotoxicity tests were performed on both alloys in cultured epithelial cells from human gingiva. The cytotoxicity investigations included both MTT tests and morphological observations. It is shown that although the ternary alloy is characterised by a narrower hysteresis and superior mechanical properties, including fatigue resistance, its cytotoxicity is higher than that of the binary alloy. This is thought to arise from the release of copper ions in the medium, which upon atomic absorption spectroscopy measurements amount to approximately 2.8 microg cm(-2) for an incubation period of 7 days.

Spontaneous incorporation of gold in palladium-based ternary nanoparticles makes durable electrocatalysts for oxygen reduction reaction

PubMed Central

Wang, Deli; Liu, Sufen; Wang, Jie; Lin, Ruoqian; Kawasaki, Masahiro; Rus, Eric; Silberstein, Katharine E.; Lowe, Michael A.; Lin, Feng; Nordlund, Dennis; Liu, Hongfang; Muller, David A.; Xin, Huolin L.; Abruña, Héctor D.

2016-01-01

Replacing platinum by a less precious metal such as palladium, is highly desirable for lowering the cost of fuel-cell electrocatalysts. However, the instability of palladium in the harsh environment of fuel-cell cathodes renders its commercial future bleak. Here we show that by incorporating trace amounts of gold in palladium-based ternary (Pd6CoCu) nanocatalysts, the durability of the catalysts improves markedly. Using aberration-corrected analytical transmission electron microscopy in conjunction with synchrotron X-ray absorption spectroscopy, we show that gold not only galvanically replaces cobalt and copper on the surface, but also penetrates through the Pd–Co–Cu lattice and distributes uniformly within the particles. The uniform incorporation of Au provides a stability boost to the entire host particle, from the surface to the interior. The spontaneous replacement method we have developed is scalable and commercially viable. This work may provide new insight for the large-scale production of non-platinum electrocatalysts for fuel-cell applications. PMID:27336795

Structural and optical properties of Cu2ZnSnS4 synthesized by ultrasonic assisted sol-gel method

NASA Astrophysics Data System (ADS)

Rajwar, Birendra Kumar; Sharma, Shailendra Kumar

2018-05-01

Cu2ZnSnS4 (CZTS) nanocrystals were synthesized by a simple ultrasonic assisted sol-gel method using two different solvents. Structure and purity of the phase formed were investigated using X-ray diffraction (XRD) and Raman measurements. The average crystallite size were estimated by using Scherrer's formula and found to be 2.09 and 7.15 nm. Raman study reveals the kesterite-phase of prepared samples. The influence of solvent in the morphologies of prepared samples was investigated by field emission scanning electron microscopy (FESEM). Ultraviolet-visible-near-infrared absorption measurement was carried out to calculate the optical band gap of samples. Oxidation state of the constitute elements of as-prepared samples were investigated by X-ray photoelectron spectroscopy (XPS) analysis and the results are in good agreement with the literature. The surface area and pore volume were estimated after analysis of nitrogen adsorption-desorption isotherm curves and found to be 16.5 m2/gm and 0.01 cm3/gm respectively.

The electronic spectra and the structures of the individual copper(II) chloride and bromide complexes in acetonitrile according to steady-state absorption spectroscopy and DFT/TD-DFT calculations

NASA Astrophysics Data System (ADS)

Olshin, Pavel K.; Myasnikova, Olesya S.; Kashina, Maria V.; Gorbunov, Artem O.; Bogachev, Nikita A.; Kompanets, Viktor O.; Chekalin, Sergey V.; Pulkin, Sergey A.; Kochemirovsky, Vladimir A.; Skripkin, Mikhail Yu.; Mereshchenko, Andrey S.

2018-03-01

The results of spectrophotometric study and quantum chemical calculations for copper(II) chloro- and bromocomplexes in acetonitrile are reported. Electronic spectra of the individual copper(II) halide complexes were obtained in a wide spectral range 200-2200 nm. Stability constants of the individual copper(II) halide complexes in acetonitrile were calculated: log β1 = 8.5, log β2 = 15.6, log β3 = 22.5, log β4 = 25.7 for [CuCln]2-n and log β1 = 17.0, log β2 = 24.6, log β3 = 28.1, log β4 = 30.4 for [CuBrn]2-n. Structures of the studied complexes were optimized and electronic spectra were simulated using DFT and TD-DFT methodologies, respectively. According to the calculations, the more is the number of halide ligands the less is coordination number of copper ion.

Heavy metal determinations in algae and clams and their possible employment for assessing the sea water quality criteria.

PubMed

Locatelli, C; Fabbri, D; Torsi, G

2001-01-01

An empirical criterion for a possible classification of sea water quality is proposed. It is based on the knowledge of metal content in algae (Ulva Rigida) and clams (Tapes Philippinarum), two species present in marine ecosystems. The elements considered are Hg, Cu, Pb, Cd, Zn. The analytical technique employed is Differential Pulse Anodic Stripping Voltammetry (DPASV) in the case of Cu, Pb, Cd, Zn, while the determination of mercury is obtained by the Cold Vapour Atomic Absorption Spectroscopy (CV-AAS) technique with SnCl2 as reducing agent. The analytical procedure has been verified on three standard reference materials: Sea Water BCR-CRM 403, Ulva Lactuca BCR-CRM 279 and Mussel Tissue BCR-CRM 278. For all the elements, in addition to detection limits, accuracy and precision are given: the former, expressed as relative error (e), and the latter, expressed as relative standard deviation (Sr), were in all cases lower than 6%.

Spontaneous incorporation of gold in palladium-based ternary nanoparticles makes durable electrocatalysts for oxygen reduction reaction

DOE PAGES

Wang, Deli; Liu, Sufen; Wang, Jie; ...

2016-06-23

Replacing platinum by a less precious metal such as palladium, is highly desirable for lowering the cost of fuel-cell electrocatalysts. However, the instability of palladium in the harsh environment of fuel-cell cathodes renders its commercial future bleak. Here we show that by incorporating trace amounts of gold in palladium-based ternary (Pd6CoCu) nanocatalysts, the durability of the catalysts improves markedly. Using aberration-corrected analytical transmission electron microscopy in conjunction with synchrotron X-ray absorption spectroscopy, we show that gold not only galvanically replaces cobalt and copper on the surface, but also penetrates through the Pd–Co–Cu lattice and distributes uniformly within the particles. Themore » uniform incorporation of Au provides a stability boost to the entire host particle, from the surface to the interior. The spontaneous replacement method we have developed is scalable and commercially viable. This work may provide new insight for the large-scale production of non-platinum electrocatalysts for fuel-cell applications.« less

Oxidation-induced spin reorientation in Co adatoms and CoPd dimers on Ni/Cu(100)

NASA Astrophysics Data System (ADS)

Chen, K.; Beeck, T.; Fiedler, S.; Baev, I.; Wurth, W.; Martins, M.

2016-04-01

Ultrasmall magnetic clusters and adatoms are of strong current interest because of their possible use in future technological applications. Here, we demonstrate that the magnetic coupling between the adsorbates and the substrate can be significantly changed through oxidation. The magnetic properties of Co adatoms and CoPd dimers deposited on a remanently magnetized Ni/Cu(100) substrate have been investigated by x-ray absorption and x-ray magnetic circular dichroism spectroscopy at the Co L2 ,3 edges. Using spectral differences, pure and oxidized components are distinguished, and their respective magnetic moments are determined. The Co adatoms and the CoPd dimers are coupled ferromagnetically to the substrate, while their oxides, Co-O and CoPd-O, are coupled antiferromagnetically to the substrate. Along with the spin reorientation from the pure to the oxidized state, the magnetic moment of the adatom is highly reduced from Co to Co-O. In contrast, the magnetic moment of the dimer is of similar order for CoPd and CoPd-O.

Trap and transfer. two-step hole injection across the Sb2S3/CuSCN interface in solid-state solar cells.

PubMed

Christians, Jeffrey A; Kamat, Prashant V

2013-09-24

In solid-state semiconductor-sensitized solar cells, commonly known as extremely thin absorber (ETA) or solid-state quantum-dot-sensitized solar cells (QDSCs), transfer of photogenerated holes from the absorber species to the p-type hole conductor plays a critical role in the charge separation process. Using Sb2S3 (absorber) and CuSCN (hole conductor), we have constructed ETA solar cells exhibiting a power conversion efficiency of 3.3%. The hole transfer from excited Sb2S3 into CuSCN, which limits the overall power conversion efficiency of these solar cells, is now independently studied using transient absorption spectroscopy. In the Sb2S3 absorber layer, photogenerated holes are rapidly localized on the sulfur atoms of the crystal lattice, forming a sulfide radical (S(-•)) species. This trapped hole is transferred from the Sb2S3 absorber to the CuSCN hole conductor with an exponential time constant of 1680 ps. This process was monitored through the spectroscopic signal seen for the S(-•) species in Sb2S3, providing direct evidence for the hole transfer dynamics in ETA solar cells. Elucidation of the hole transfer mechanism from Sb2S3 to CuSCN represents a significant step toward understanding charge separation in Sb2S3 solar cells and provides insight into the design of new architectures for higher efficiency devices.

Chrysocolla Redefined as Spertiniite

NASA Astrophysics Data System (ADS)

Farges, François; Benzerara, Karim; Brown, Gordon E.

2007-02-01

XAFS and μ-XAFS spectra were collected at the Cu K-edge for seven chrysocolla samples (Peru, USA, and Congo). The results suggest that that the local structure around Cu is similar to that in Cu(OH)2 (spertiniite). Cu-L3 STXM imaging and spectroscopy confirm that the chrysocolla samples examined here consist of mesoscopic Cu(II)-rich domains surrounded by Si-rich domains (in agreement with results from infra-red spectroscopy). Hence, we suggest that chrysocolla, which is generally considered to be orthorhombic with composition (Cu,Al)2H2Si2O5(OH)4ṡnH2O, is in actually a mesoscopic assemblage composed dominantly of spertiniite (Cu(OH)2), water and amorphous silica (SiO2).

Synthesis and Absorption Properties of Hollow-spherical Dy2Cu2O5 via a Coordination Compound Method with [DyCu(3,4-pdc)2(OAc)(H2O)2]•10.5H2O Precursor.

PubMed

Liu, Xuanwen; You, Junhua; Wang, Renchao; Ni, Zhiyuan; Han, Fei; Jin, Lei; Ye, Zhiqi; Fang, Zhao; Guo, Rui

2017-10-12

Dy 2 Cu 2 O 5 nanoparticles with perovskite structures were synthesized via a simple solution method (SSM) and a coordination compound method (CCM) using [DyCu(3,4-pdc) 2 (OAc)(H 2 O) 2 ]•10.5H 2 O (pdc = 3,4-pyridinedicarboxylic acid) as precursor. The as-prepared samples were structurally characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy (XPS) and standard Brunauer-Emmett-Teller (BET) methods. Compared to the aggregated hexahedral particles prepared by SSM, the Dy 2 Cu 2 O 5 of CCM showed hollow spherical morphology composed of nanoparticles with average diameters of 100-150 nm and a larger special surface area up to 36.5 m 2 /g. The maximum adsorption capacity (Q m ) of CCM for malachite green (MG) determined by the adsorption isotherms with different adsorbent dosages of 0.03-0.07 g, reached 5.54 g/g at room temperature. The thermodynamic parameters of adsorption process were estimated by the fittings of the isotherms at 298, 318, and 338 K, and the kinetic parameters were obtained from the time-dependent adsorption isotherms. The results revealed that the adsorption process followed a pseudo-second-order reaction. Finally, the adsorption mechanism was studied using a competitive ion (CI) experiments, and the highly efficient selective adsorption was achieved due to strong O-Cu and O-Dy coordination bonds between Dy 2 Cu 2 O 5 and MG.

Characterization and copper binding properties of human COMMD1 (MURR1).

PubMed

Narindrasorasak, Suree; Kulkarni, Prasad; Deschamps, Patrick; She, Yi-Min; Sarkar, Bibudhendra

2007-03-20

COMMD1 (copper metabolism gene MURR1 (mouse U2af1-rs1 region1) domain) belongs to a family of multifunctional proteins that inhibit nuclear factor NF-kappaB. COMMD1 was implicated as a regulator of copper metabolism by the discovery that a deletion of exon 2 of COMMD1 causes copper toxicosis in Bedlington terriers. Here, we report the detailed characterization and specific copper binding properties of purified recombinant human COMMD1 as well as that of the exon 2 product, COMMD(61-154). By using various techniques including native-PAGE, EPR, UV-visible electronic absorption, intrinsic fluorescence spectroscopies as well as DEPC modification of histidines, we demonstrate that COMMD1 specifically binds copper as Cu(II) in 1:1 stoichiometry and does not bind other divalent metals. Moreover, the exon 2 product, COMMD(61-154), alone was able to bind Cu(II) as well as the wild type protein, with a stoichiometry of 1 mol of Cu(II) per protein monomer. The protection of DEPC modification of COMMD1 by Cu(II) implied that Cu(II) binding involves His residues. Further investigation by DEPC modification of COMMD(61-154) and subsequent MALDI MS mapping and MS/MS sequencing identified the protection of His101 and His134 residues in the presence of Cu(II). Fluorescence studies of single point mutants of the full-length protein revealed the involvement of M110 in addition to H134 in direct Cu(II) binding. Taken together, the data provide insight into the function of COMMD1 and especially COMMD(61-154), a product of exon 2 that is deleted in terriers affected by copper toxicosis, as a regulator of copper homeostasis.

Memory and Learning Dysfunction Following Copper Toxicity: Biochemical and Immunohistochemical Basis.

PubMed

Kalita, Jayantee; Kumar, Vijay; Misra, Usha K; Bora, Himangsu K

2018-05-01

The prototype disease of Cu toxicity in human is Wilson disease, and cognitive impairment is the presenting symptom of it. There is no study correlating Cu-induced excitotoxicity, apoptosis, and astrocytic reaction with memory dysfunction. We report excitotoxicity, apoptosis, and astrocytic reaction of the hippocampus and frontal cortex with memory dysfunction in rat model of Cu toxicity. Thirty-six rats were divided into group I (control) and group II (100 mg/kgBwt/day CuSO 4 orally). Y-maze was performed for memory and learning at 0, 30, 60, and 90 days. Frontal and hippocampal free Cu concentration, oxidative stress markers [glutathione (GSH), total antioxidant toxicity (TAC), and malondialdehyde (MDA)], and glutamate were measured by atomic absorption spectroscopy, spectrophotometry, and ELISA, respectively. N-methyl-D-aspartate receptors (NMDARs) NR1, NR2A, and NR2B were done by real-time polymerase chain reaction. Immunohistochemistry for caspase-3 and glial fibrillary acidic protein (GFAP) were done and quantified using the ImageJ software. The glutamate level in hippocampus was increased, and NMDAR expression was decreased at 30, 60, and 90 days in group II compared to group I. In the frontal cortex, glutamate was increased at 90 days, but NMDARs were not significantly different in group II compared to group I. Caspase-3 and GFAP expressions were also higher in group II compared to group I, and these changes were more marked in hippocampus than frontal cortex. These changes correlated with respective free tissue Cu, oxidative stress, and Y-maze attention score. Cu toxicity induces apoptosis and astrocytosis of the hippocampus and frontal cortex through direct or glutamate and oxidative stress pathways, and results in impaired memory and learning.

The saturable absorption and reverse saturable absorption properties of Cu doped zinc oxide thin films

NASA Astrophysics Data System (ADS)

Yao, Cheng-Bao; Wen, Xin; Li, Qiang-Hua; Yan, Xiao-Yan; Li, Jin; Zhang, Ke-Xin; Sun, Wen-Jun; Bai, Li-Na; Yang, Shou-Bin

2017-03-01

We present the structure and nonlinear absorption (NLA) properties of Cu-doped ZnO (CZO) films prepared by magnetron sputtering. The films were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that the CZO films can maintain a wurtzite structure. Furthermore, the open-aperture (OA) Z-scan measurements of the film were carried out by nanosecond laser pulse. A transition from saturable absorption (SA) to reverse saturable absorption (RSA) was observed as the excitation intensity increasing. With good excellent nonlinear optical coefficient, the samples were expected to be the potential applications in optical devices.

Synthesis and Characterization of Phase-pure Copper Zinc Tin Sulfide (Cu2ZnSnS4) Nanoparticles

NASA Astrophysics Data System (ADS)

Monahan, Bradley Michael

Semiconductor nanoparticles have been an important area of research in many different disciplines. A substantial amount of this work has been put toward advancing the field of photovoltaics. However, current p-type photovoltaic materials can not sustain the large scale production needed for future energy demands due to their low elemental abundance. Therefore, Earth abundant semiconductor materials have become of great interest to the photovoltaic community especially, the material copper zinc tin sulfide (CZTS), also known by its mineral name kesterite. CZTS exhibits desirable properties for photovoltaics, such as elemental abundance, high absorption coefficient (~104 cm-1 ), high carrier concentration, and optimum direct band gap (1.5 eV). To date, solution based approaches for making CZTS have yielded the most promising conversion efficiencies in solar cells. To that end, the motivation of nanoparticle based inks that can be used in high throughput production are an attractive route for large scale deployment. This has driven the need to make high quality CZTS nanoparticles that possess the properties of the pure kesterite phase with high monodispersity that can be deposited into dense thin films. The inherent challenge of making a quaternary compound of a single phase has made this a difficult task; however, some of those fundamental problems are addressed in this thesis. This had resulted in the synthesis of phase-pure k-CZTS confirmed by powder X-ray diffraction, Raman spectroscopy, UV-visible absorption spectroscopy and energy dispersive x-ray spectroscopy. Furthermore, ultra-fast laser spectroscopy was done on CZTS thin films made from phase-pure kesterite nanoparticles synthesized in this work. This thesis provides new data that directly probes the lifetime of photogenerated free carriers in kesterite CZTS (k-CZTS) thin films.

Zerovalent Copper Intercalated Birnessite as a Cathode for Lithium Ion Batteries: Extending Cycle Life

DOE PAGES

Li, Yue Ru; Poyraz, Altug S.; Hu, Xiaobing; ...

2017-01-01

Birnessite type layered manganese dioxides (δ-MnO 2) have attracted considerable attention in recent years as 2D intercalation cathodes for rechargeable Li +, Na +, and Mg 2+ batteries due to fast ion diffusion through their negatively charged δ-MnO 2 sheets separated by interlayer cations and a stable Mn 3+/4+ redox couple. Here we report the preparation and electrochemistry of zero and divalent copper co-intercalated birnessite type manganese dioxide (Cu 0 0.03Cu 2+ 0.21Na 0.12MnO 2·0.9H 2O). The copper intercalated birnessite materials were fully characterized utilizing powder X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), transmission electron microscopy (TEM).more » The mixed valent nature of intercalated Cu 0 and Cu 2+ was confirmed by X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). Electrochemical evaluation results show that zero valent copper intercalated birnessite exhibits higher discharge capability, improved cyclability, and lower impedance compared to the Cu 2+ only intercalated (Cu 0.26MnO 2·1.0H 2O) and Cu free Na birnessite (Na 0.40MnO 2·1.0H 2O) materials. Remarkably, zero valent copper birnessite shows almost no fade after 10 cycles at 0.1 mV/s. Electrochemical impedance spectroscopy results suggest that charge transfer resistivity of Cu 0 modified samples was much lower than that of Cu 2+ and Cu free birnessite, indicating that the presence of a small amount of Cu 0 improves the conductivity of birnessite and results in better electrochemical cyclability, rate capability, and lower impedance.« less

Surface-Enhanced Resonance Raman Scattering and Visible Extinction Spectroscopy of Copper Chlorophyllin: An Upper Level Chemistry Experiment

ERIC Educational Resources Information Center

Schnitzer, Cheryl S.; Reim, Candace Lawson; Sirois, John J.; House, Paul G.

2010-01-01

Advanced chemistry students are introduced to surface-enhanced resonance Raman scattering (SERRS) by studying how sodium copper chlorophyllin (CuChl) adsorbs onto silver colloids (CuChl/Ag) as a function of pH. Using both SERRS and visible extinction spectroscopy, the extent of CuChl adsorption and colloidal aggregation are monitored. Initially at…

Copper Solubility and Speciation in Mineral-Buffered Fluids at Crust to Upper Mantle Conditions

NASA Astrophysics Data System (ADS)

Hack, A. C.; Mavrogenes, J. A.; Berry, A. J.

2003-12-01

Fluid inclusions, synthesised in a piston-cylinder apparatus, were used to trap representative high P-T fluid samples under mineral-buffered conditions in the systems Cu2O-MgO-SiO2-HCl-H2O and Cu-K2O-Al2O3-SiO2-Fe3O4-Fe2O3-HCl-H2O at up to 850° C and 1.7 GPa, and as a function of salinity to 11 mol/kg Cl. Copper solubility and speciation were obtained by analysing individual fluid inclusions by excimer laser ablation inductively coupled mass spectrometry (LA-ICP-MS), proton induced X-ray emission (PIXE) and Cu K-edge X-ray absorption near edge structure (XANES) spectroscopy. Quenched capsule fluids were also analysed. At 710° C copper-cuprite-talc-quartz solubility in aqueous fluid containing 1 mol/kg Cl increases with P to at least 1.7 GPa. Conspicuously, with increasing P (> ˜ 0.5 GPa) talc solubility increases and molal Cu concentrations exceed those of Cl. Isothermal Cu solubility appears to mimic the solubility isopleths in the SiO2-H2O system. Solubility trends suggest that the stability field of copper(I) hydroxide complexes (e.g. Cu(OH)aq) expands to higher salinities such that H2O may become an effective ligand at high-P. At constant P (e.g. 0.35 GPa) solubility decreases with increasing T (i.e. > 525° C). High-T Cu K-edge XANES spectra of single homogenised synthetic fluid inclusions indicate that highly coordinated chlorocopper(I) complexes (e.g. Cu:Cl, 1:3 to 4) predominate at high salinity, whereas lower-order linear Cu-Cl coordination predominates at lower salinities, in fluids buffered by quartz-talc-copper-cuprite. This is consistent with the interpretation of the solubility data. At equivalent salinity, T and P conditions, spectra for fluids buffered by native copper-orthoclase-sillimanite-quartz-magnetite-hematite show no evidence for higher-order chlorocopper(I) complexes. Preliminary extended X-ray absorption fine structure data for these latter inclusions indicate that [CuCl2]- predominates. The stability of higher-order complexes is strongly coupled to HCl concentrations, which at constant P and T is determined by both the specific mineral assemblage and total salinity. This is the first spectroscopic evidence for highly coordinated chlorocopper(I) complexes in supercritical fluids. Furthermore, the speciation dependence on the buffering mineral assemblage has not been recognized previously. Similarly, this is the first experimental confirmation that copper concentrations in mineral-buffered fluids can be extremely high, e.g. ˜ 10 wt%, substantiating inferences based on natural fluid inclusions associated with porphyry copper ore deposits.

Spin tuning of electron-doped metal-phthalocyanine layers.

PubMed

Stepanow, Sebastian; Lodi Rizzini, Alberto; Krull, Cornelius; Kavich, Jerald; Cezar, Julio C; Yakhou-Harris, Flora; Sheverdyaeva, Polina M; Moras, Paolo; Carbone, Carlo; Ceballos, Gustavo; Mugarza, Aitor; Gambardella, Pietro

2014-04-09

The spin state of organic-based magnets at interfaces is to a great extent determined by the organic environment and the nature of the spin-carrying metal center, which is further subject to modifications by the adsorbate-substrate coupling. Direct chemical doping offers an additional route for tailoring the electronic and magnetic characteristics of molecular magnets. Here we present a systematic investigation of the effects of alkali metal doping on the charge state and crystal field of 3d metal ions in Cu, Ni, Fe, and Mn phthalocyanine (Pc) monolayers adsorbed on Ag. Combined X-ray absorption spectroscopy and ligand field multiplet calculations show that Cu(II), Ni(II), and Fe(II) ions reduce to Cu(I), Ni(I), and Fe(I) upon alkali metal adsorption, whereas Mn maintains its formal oxidation state. The strength of the crystal field at the Ni, Fe, and Mn sites is strongly reduced upon doping. The combined effect of these changes is that the magnetic moment of high- and low-spin ions such as Cu and Ni can be entirely turned off or on, respectively, whereas the magnetic configuration of MnPc can be changed from intermediate (3/2) to high (5/2) spin. In the case of FePc a 10-fold increase of the orbital magnetic moment accompanies charge transfer and a transition to a high-spin state.

X-ray absorption spectroscopic studies of the active sites of nickel- and copper-containing metalloproteins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Grace O.

1993-06-01

X-ray absorption spectroscopy (XAS) is a useful tool for obtaining structural and chemical information about the active sites of metalloproteins and metalloenzymes. Information may be obtained from both the edge region and the extended X-ray absorption fine structure (EXAFS) or post-edge region of the K-edge X-ray absorption spectrum of a metal center in a compound. The edge contains information about the valence electronic structure of the atom that absorbs the X-rays. It is possible in some systems to infer the redox state of the metal atom in question, as well as the geometry and nature of ligands connected to it,more » from the features in the edge in a straightforward manner. The EXAFS modulations, being produced by the backscattering of the ejected photoelectron from the atoms surrounding the metal atom, provide, when analyzed, information about the number and type of neighbouring atoms, and the distances at which they occur. In this thesis, analysis of both the edge and EXAFS regions has been used to gain information about the active sites of various metalloproteins. The metalloproteins studied were plastocyanin (Pc), laccase and nickel carbon monoxide dehydrogenase (Ni CODH). Studies of Cu(I)-imidazole compounds, related to the protein hemocyanin, are also reported here.« less

Optical and electrical properties of copper-incorporated ZnS films applicable as solar cell absorbers

NASA Astrophysics Data System (ADS)

Mehrabian, M.; Esteki, Z.; Shokrvash, H.; Kavei, G.

2016-10-01

Un-doped and Cu-doped ZnS (ZnS:Cu) thin films were synthesized by Successive Ion Layer Absorption and Reaction (SILAR) method. The UV-visible absorption studies have been used to calculate the band gap values of the fabricated ZnS:Cu thin films. It was observed that by increasing the concentration of Cu2+ ions, the Fermi level moves toward the edge of the valence band of ZnS. Photoluminescence spectra of un-doped and Cu-doped ZnS thin films was recorded under 355 nm. The emission spectrum of samples has a blue emission band at 436 nm. The peak positions of the luminescence showed a red shift as the Cu2+ ion concentration was increased, which indicates that the acceptor level (of Cu2+) is getting close to the valence band of ZnS.

Optical and EPR studies of barium alumino borate glasses containing Cu2+ ions

NASA Astrophysics Data System (ADS)

Ahmed, Mohamad Raheem; Phani, A. V. Lalitha; Narsimha Chary, M.; Shareefuddin, Md.

2018-05-01

Glass containing Cu2+ ions in (30-x) BaO-xAl2O3-69.5B2O3-0.5CuO (0 ≤ x ≤ 15 mol %) were prepared by the conventional melt quenching technique. Peak free X-ray diffractograms confirmed the amorphous nature of the glass samples. Spectroscopic studies such as optical absorption, EPR were studied to understand the effect of modifier oxide and CuO dopant. From EPR spectra the spin-Hamiltonian parameter were evaluated. The ground state of Cu2+ is dx2-y2 (2B1g state) and the site symmetry around Cu2+ is tetragonally distorted octahedral. A broad optical absorption band was observed for all the glasses containing Cu2+ ions corresponding to the 2B1g → 2B2g transition. The optical band gap and Urbach energy values are calculated.

Flux flow induced microwave absorption in high temperature superconductor Bi 2-XPb XSr 2Ca N-1Cu NO 4+2N

NASA Astrophysics Data System (ADS)

Owens, F. J.

1990-12-01

Direct measurements of microwave absorption without use of rf H field modulation in granular composites of the 115 K superconductor Bi 2-XPb XSr 2Ca N-1Cu NO 4+2N as a function of magnetic field above 0.1 T reveal a continuing increase of absorption of microwave energy increasing magnetic field. The temperature and magnetic field dependence of the absorption are very different from the low magnetic field (<0.01 T) absorption arising from weak links in the material. The magnetic field and temperature dependence are consistent with the behavior of thermally activated flux flow resistance suggesting the absorption is due to flux creep.

Quinoline containing acetyl hydrazone: An easily accessible switch-on optical chemosensor for Zn2 +

NASA Astrophysics Data System (ADS)

Wu, Wei-Na; Mao, Pan-Dong; Wang, Yuan; Zhao, Xiao-Lei; Xu, Zhou-Qing; Xu, Zhi-Hong; Xue, Yuan

2018-01-01

A simple chemosensor, namely, N-((quinolin-8-yl)methylene)acetohydrazide (1) was synthesized and used as an off-on fluorescence sensor, which exhibits high selectivity toward Zn2 + in aqueous media. The probe has large Stokes shift of > 200 nm, and its detection limit for Zn2 + is 89.3 nM. The binding process was confirmed through UV-vis absorption analysis, fluorescence measurements, mass spectroscopy study, 1H NMR spectra and density functional theory calculation. The crystal structures of Zn2 +, Ni2 +, and Cu2 + complexes based on 1 were determined through X-ray crystallographic analysis. The fluorescent probe was then applied to monitor intracellular Zn2 + in HeLa cells.

Q-switched Yb3+:YAG laser using plasmonic Cu2-xSe quantum dots as saturable absorbers

NASA Astrophysics Data System (ADS)

Wang, Yimeng; Zhan, Yi; Lee, Sooho; Wang, Li; Zhang, Xinping

2018-04-01

Cu2-xSe quantum dots (QDs) were synthesized by organometallic synthesis methods. Due to heavy self-doping, the Cu2-xSe QDs exhibit particle plasmon resonance in the near-infrared. Transient absorption spectroscopic investigation revealed strong nonlinear optical absorption and bleaching performance of the QDs under femtosecond pulse excitation, which enabled the Cu2-xSe QDs to be excellent saturable absorbers and applied in Q-switched or mode-locked lasers. A passively Q-switched Yb3+:YAG solid-state laser at 1.03 μm was achieved by coating Cu2-xSe QDs as saturable absorbers onto one of the output coupler of the V-shaped linear cavity.

Effect of arbuscular mycorrhizal fungi on young vines in copper-contaminated soil

PubMed Central

Ambrosini, Vítor Gabriel; Voges, Joana Gerent; Canton, Ludiana; Couto, Rafael da Rosa; Ferreira, Paulo Ademar Avelar; Comin, Jucinei José; de Melo, George Wellington Bastos; Brunetto, Gustavo; Soares, Cláudio Roberto Fonsêca Sousa

2015-01-01

Abstract High copper (Cu) levels in uprooted old vineyard soils may cause toxicity in transplanted young vines, although such toxicity may be reduced by inoculating plants with arbuscular mycorrhizal fungi (AMF). The objective of this study was to evaluate the effects of AMF on the plant growth, chlorophyll contents, mycorrhizal colonization, and Cu and phosphorus (P) absorption in young vines cultivated in a vineyard soil contaminated by Cu. Commercial vineyard soil with high Cu levels was placed in plastic tubes and transplanted with young vines, which were inoculated with six AMF species (Dentiscutata heterogama, Gigaspora gigantea, Acaulospora morrowiae, A. colombiana, Rhizophagus clarus, R. irregularis) and a control treatment on randomized blocks with 12 replicates. After 130 days, the mycorrhizal colonization, root and shoot dry matter (DM), height increment, P and Cu absorption, and chlorophyll contents were evaluated. The height increment, shoot DM and chlorophyll contents were not promoted by AMF, although the root DM was increased by R. clarus and R. irregularis, which had the greatest mycorrhizal colonization and P uptake. AMF increased Cu absorption but decreased its transport to shoots. Thus, AMF species, particularly R. clarus and R. irregularis, contribute to the establishment of young vines exposed to high Cu levels. PMID:26691462

High absorption coefficients of the CuSb(Se,Te)2 and CuBi(S,Se)2 alloys enable high-efficient 100 nm thin-film photovoltaics

NASA Astrophysics Data System (ADS)

Chen, Rongzhen; Persson, Clas

2017-06-01

We demonstrate that the band-gap energies Eg of CuSb(Se,Te)2 and CuBi(S,Se)2 can be optimized for high energy conversion in very thin photovoltaic devices, and that the alloys then exhibit excellent optical properties, especially for tellurium rich CuSb(Se1-xTex)2. This is explained by multi-valley band structure with flat energy dispersions, mainly due to the localized character of the Sb/Bi p-like conduction band states. Still the effective electron mass is reasonable small: mc ≈ 0.25m0 for CuSbTe2. The absorption coefficient α(ω) for CuSb(Se1-xTex)2 is at ħω = Eg + 1 eV as much as 5-7 times larger than α(ω) for traditional thin-film absorber materials. Auger recombination does limit the efficiency if the carrier concentration becomes too high, and this effect needs to be suppressed. However with high absorptivity, the alloys can be utilized for extremely thin inorganic solar cells with the maximum efficiency ηmax ≈ 25% even for film thicknesses d ≈ 50 - 150 nm, and the efficiency increases to ˜30% if the Auger effect is diminished.

Understanding and Control of Bipolar Self-Doping in Copper Nitride

PubMed Central

Fioretti, Angela N.; Schwartz, Craig P.; Vinson, John; Nordlund, Dennis; Prendergast, David; Tamboli, Adele C.; Caskey, Christopher M.; Tuomisto, Filip; Linez, Florence; Christensen, Steven T.; Toberer, Eric S.; Lany, Stephan; Zakutayev, Andriy

2016-01-01

Semiconductor materials that can be doped both n-type and p-type are desirable for diode-based applications and transistor technology. Copper nitride (Cu3N) is a metastable semiconductor with a solar-relevant bandgap that has been reported to exhibit bipolar doping behavior. However, deeper understanding and better control of the mechanism behind this behavior in Cu3N is currently lacking in the literature. In this work, we use combinatorial growth with a temperature gradient to demonstrate both conduction types of phase-pure, sputter-deposited Cu3N thin films. Room temperature Hall effect and Seebeck effect measurements show n-type Cu3N with an electron density of 1017 cm−3 for low growth temperature (≈ 35 °C) and p-type with a hole density between 1015 cm−3 and 1016 cm−3 for elevated growth temperatures (50 °C to 120 °C). Mobility for both types of Cu3N was ≈ 0.1 cm2/Vs to 1 cm2/V. Additionally, temperature-dependent Hall effect measurements indicate that ionized defects are an important scattering mechanism in p-type films. By combining X-ray absorption spectroscopy and first-principles defect theory, we determined that VCu defects form preferentially in p-type Cu3N while Cui defects form preferentially in n-type Cu3N; suggesting that Cu3N is a compensated semiconductor with conductivity type resulting from a balance between donor and acceptor defects. Based on these theoretical and experimental results, we propose a kinetic defect formation mechanism for bipolar doping in Cu3N, that is also supported by positron annihilation experiments. Overall, the results of this work highlight the importance of kinetic processes in the defect physics of metastable materials, and provide a framework that can be applied when considering the properties of such materials in general. PMID:27746508