Shift Of Cu Research Articles

Single Doping for Triple Functions: Integrated Theranostic Nanoplatforms for Multimodal Image-Guided Tumor Therapy.

Accurate location and efficient treatment of diseases by multifunctional nanoplatforms are appealing but face great challenges. Theranostic agents through the physical combination of different functional nanoparticles are demonstrated to be effective. Yet, the complicated biological environment often leads to ambiguous fates of each agent, which fails to keep the behaviors of imaging and therapeutic components in a simultaneous manner. Herein, "integrated" theranostic NPs, Gd-doped CuWO4 (CWG) with strong near-infrared (808nm) absorption, the longest absorption peak of reported CuWO4 , located in the biological transparent window, are constructed. The single doping of trace amount of Gd not only endows them with a distinguished magnetic resonance imaging capability (r1 = 12.01 mM-1 s-1 ), but also concurrently imposes great effect on the valence states of matrix ion (Cu), as evidenced by theoretical calculation results. The charge distribution shift of Cu would facilitate ·OH generation, beneficial for chemodynamic therapy (CDT). Moreover, CWG NPs display remarkable photoacoustic (PA) and computed tomography (CT) imaging capabilities (S = 10.33 HU mM-1 ). Such integrated theranostics afford a paradigm for multimodal imaging-guided synergistic therapy with all-in-one single nanoparticle.

Pd-modified CuO-ZnO-Al2O3 catalysts via mixed-phases-containing precursor for methanol synthesis from CO2 hydrogenation under mild conditions

A series of palladium-modified (Pd-modified) CuO-ZnO-Al2O3 (CZA) catalysts with various Pd loadings (0.3 wt% to 2.4 wt%) were prepared using the wetness impregnation method, on two CZA supports with different structures that are CZA-aged precursor composed of a mixture of zincian-malachite and hydrotalcite-like phases (CZA-zH), and CuO-ZnO-Al2O3 metal oxide nanoparticles (CZA-MO). Enhancement on catalytic activity can be observed on both Pd-modified CZA catalysts in a temperature range of 180–240 °C for methanol synthesis via CO2 hydrogenation. Pd/CZA-zH catalysts exhibited a more efficient and stable production of methanol at a relatively low reaction temperature of 180 °C for 100 hrs of reaction. The improvement of activity is mainly ascribed to a higher surface area and abundant oxygen-containing functional groups (e.g., –OH) of CZA-zH support, which is beneficial for better adsorption and distribution of Pd promoter. Hydrogen temperature programmed reduction and X-ray photoelectron spectroscopy results demonstrated a better interaction between Pd and Cu on Pd/CZA-zH catalysts via enhanced reducibility of CuO, and peak shift of Cu to a lower binding energy. The difference in the efficient utilization of hydrogen spillover effect of Pd promoter over two CZA supports resulted in the different performances for methanol synthesis under mild reaction conditions.

Study of carbon supported CuPd alloy nanoparticles with Pd-rich surface for the electrochemical formate oxidation and CO2 reduction

Carbon supported copper-palladium alloy nanoparticles (CuPd/C) with Pd-rich surface synthesized via the adsorbate induced surface segregation method were tested toward both the electrochemical oxidation of formate into electricity and CO2, and the reduction of CO2 to produce formate. An upshift of the d-band center and opposite binding energy shifts of Cu and Pd core levels were experimentally observed using X-ray photoelectron spectroscopy (XPS). This perturbation of the surface electronic structure of the CuPd/C nanoparticles leads to the lowering of the bonding strength of key adsorbate species for both the formate oxidation and electrochemical CO2 reduction, which increased the catalytic activity toward both reactions. Amongst the different compositions of CuxPd1-x/C, the 20:80 molar% of Cu:Pd concentration shows an important improvement toward formate oxidation (FO) compared to the other CuxPd1-y compositions and the monometallic Pd. On the other hand, CuxPd1-x/C catalyst with the 60:40 molar% of Cu:Pd concentration shows the highest faradaic efficiency for the electrochemical CO2 reduction toward the formate production. Therefore, by selecting a bimetallic CuxPd1-x/C alloy that (1) optimizes the formate oxidation current density and (2) the faradaic efficiency of the electrochemical reduction of CO2 into formate, a novel sustainable and regenerative power source (i.e., combining a direct formate fuel cell and a CO2 reduction unit into a single regenerative energy system) could be developed.

MICRONUTRIENT STATUS OF TISTA MEANDER FLOODPLAIN SOILS UNDER MAJOR CROPPING PATTERNS IN MITHAPUKUR UPAZILA

Soil micronutrients from their finite source are strongly affected by the inclusion of high-yielding crop cultivars in the cropping patterns and their fertilization practices. A study was conducted to identify the dominant cropping patterns and to evaluate their impacts on soil micronutrients’ (Zn, B, Cu, Fe, Mn) status in Tista Meander Floodplain Soils at Mithapukur upazila of Rangpur district, Bangladesh. The study revealed that potato-rice-rice (P-R-R) (18.26%), rice-fallow-rice (R-F-R) (15.65%), and maize-fallow-rice (M-F-R) (13.91%) were the most prevalent among the existing cropping patterns. Zn and B fertilizers are used by 35% and 23% of farmers. The concentrations of Zn, B, and Mn increased while Cu and Fe decreased under all dominant patterns. The highest accumulation of Zn by 281.63%, B by 139.36%, and Mn by 83.13% were obtained under P-R-R while, the highest depletion of Cu by 52.58% and Fe by 24.48% were obtained under P-R-R and M-F-R cropping patterns, respectively. An increasing trend of soil toxicity index (STI) values was observed with Zn, B, and Mn. A deleterious shift of B from lower to higher STI class was obtained under the P-R-R and R-F-R patterns while an ameliorating shift of Cu from higher to lower class was obtained under P-R-R and M-F-R patterns. The recent STI status of Fe and Mn under all cropping patterns rendered in the ‘highly toxic’ class. This investigation emphasizes that the concentrations of selected micronutrients were found above their respective critical limits and that the studied micronutrients except Zn imposed toxicity in the soil.

The effect of hyperfine splitting on Stark broadening for three blue-green Cu i lines in laser-induced plasma

ABSTRACT Stark effect is observed in many natural and artificial plasmas and is of great importance for diagnostic purposes. Since this effect alters profiles of spectral lines, it should be taken into account when assessing chemical composition of radiation sources, including stars. Copper is one of the elements which studies of stellar atmospheres deal with. To this end, UV and visible Cu lines are used. However, there is a lack of agreement between existing data on their Stark parameters. It is therefore of interest to obtain new experimental data on these lines and to compare them to previous results. In this work, we have estimated Stark widths and shifts for three blue-green lines at 5105.54, 5153.24, and 5218.20 Å (corresponding transitions are [3d104p] 2P° → [3d94s2] 2D and [3d104d] 2D → [3d104p] 2P°) observed in a ‘long-spark’ laser-induced plasma. For the first time, we have accurately estimated an impact of hyperfine splitting on the profile shapes of the studied lines taking also into account the isotope shifts. We have shown that both effects considerably influence shift and width of Cu i line at 5105.54 Å, and shifts of Cu i lines at 5153.24 and 5218.20 Å.

Weathering behavior and metal mobility of tailings under an extremely arid climate at Jinchuan Cu-Ni sulfide deposit, Western China

A detailed mineralogical and geochemical study of a sulfide tailings impoundment was carried out in Jinchuan Cu-Ni sulfide deposit in western China. Since 1963, the tailings impoundment has been exposed to weathering in an extremely arid climate with dry-warm seasons. Samples from different depths of two boreholes, each located in the center and border of the impoundment, were analyzed to evaluate the oxidative weathering behaviors of the tailings. The obvious shift of Cu and Ni from the sulfide fraction to more mobile forms, increasing trend of SO42− in the shallow of the tailings and decreasing trend of Fe content in sulfide fraction, show direct signs of sulfides oxidation, especially in the upper part of the tailings impoundment. Besides the upward migration of Ca2+ and SO42− under the strong evaporation in hyper-arid climate, the heavy metals of Cu and Ni are retained by the in-situ adsorption and/or co-precipitation with secondary Fe3+ precipitates. These secondary minerals are poorly crystalline and unstable. So, for sulfide tailings with a simultaneous large production of carbonates and under extremely arid climate, acid pollutants can be avoided but heavy metal pollution from the windblown dust of secondary minerals is the key pollution source that should be taken seriously.

Core level shifts in Cu–Pd alloys as a function of bulk composition and structure

CuPd alloys are important materials in hydrogen purification, where they are used as dense Pd-based separation membranes. Cu is added to impart sulfur tolerance and improved mechanical properties. At intermediate compositions and T<873K, a BCC alloy (B2) phase occurs, which has superior separation characteristics to those of the FCC phases that form at high Cu and high Pd compositions. Identifying the composition and temperature window where the B2 phase forms is a critical need to enable the design of improved alloys. A composition spread alloy film of Cu and Pd was synthesized. The film was characterized by electron back scatter diffraction and X-ray photoelectron spectroscopy, providing the core level shifts as a function of bulk composition and bulk structure. An anomalous deviation in the Cu core level shift was observed in the composition range 0.33<xPd<0.55 over which the B2 phase occurs. Density functional theory calculations were used to simulate core level shifts in the FCC and B2 alloy structures. They suggest that the anomalous deviation in core level shift is due to formation of the ordered B2 phase in this composition range.

Interaction of 4-imidazolemethanol with a copper electrode revealed by isotope-edited SERS and theoretical modeling.

Adsorption of 4-imidazolemethanol (ImMeOH) on a copper electrode has been investigated by in situ isotope-edited (H/D and (63)Cu/(65)Cu) surface enhanced Raman spectroscopy (SERS) in aqueous solutions at physiological pH (7.0) in a potential window from -0.500 to -1.100 V. Theoretical modeling by DFT calculations at the B3LYP/6-311++G(d,p) level for light atoms and LANL2DZ with ECP for copper atoms have been employed for the interpretation of experimental data. The copper surface was modeled by a cluster of 6 atoms. It was found that the imidazole ring adopts Tautomer-I form in the adsorbed state and coordinates with the Cu surface through the N3 atom. Linear potential-dependence of ν(C4=C5) mode with the slope of (15 ± 1) cm(-1) V(-1) was experimentally observed. The imidazole ring mode near 1492 cm(-1) primarily due to ν(C2-N3) + β(C2H) vibration has also showed a considerable decrease in frequency at more negative electrode potentials with the slope of (9 ± 2) cm(-1) V(-1). Both modes can be used as sensitive probes for analysis of interaction of the imidazole ring with the metal surface. In agreement with experimental data theoretical modeling has predicted higher stability of surface bound Tautomer-I compared with Tautomer-II. The formation of a covalent bond between the metal and adsorbate was experimentally evidenced by metal isotopic ((63)Cu/(65)Cu) frequency shift of ν(Cu-N) mode at 222 cm(-1), combined with theoretical modeling of the surface complex.

Chemical origin of C–O blue shift and nature of Cu+…C bonding in non-classical copper carbonyl Cu+(CO)n (n = 1–8) complexes

Natural bond orbital (NBO) method and atoms-in-molecules (AIM) theory are used to study the chemical origin in the direction and ordering of C–O frequency shift, as well as Cu+…C bond nature in copper carbonyl cations Cu+(CO)n (n = 1–8). This study emphasises the role of π-back donation in explaining the ordering of C–O blue shift. NBO analyses show that the interplay of two competing factors, including π-back donation and rehybridization, is responsible for both the direction and the ordering of C–O stretching frequency shift in Cu+(CO)n (n = 1–8) complexes. In addition, the Cu+…C interaction is interesting because Cu+(CO)n (n = 1–4) structure has one-sphere CO ligands but Cu+(CO)n (n = 5–8) has two-sphere CO ligands. Topological analyses of electron density are applied to characterise the Cu+…C interactions of first- and second-sphere CO with Cu+ and to explore the Cu+…C interactions in the nature.

Effect of N doping on hole density of Cu2O:N films prepared by the reactive magnetron sputtering method

N-doped Cu 2 O thin films have been deposited on glass substrate by reactive magnetron sputtering method under various N 2 /O 2 flow ratios from 0 to 1.0. The structural and electronic properties of Cu 2 O:N films were investigated by X-ray diffraction (XRD), four-point probe and Hall effect measurements. XRD pattern showed that crystalline structures of all the samples retained single phase of Cu 2 O with the increase of N 2 /O 2 flow ratio from 0 to 1.0. However, the crystalline quality of Cu 2 O:N films reduced with the increase of the N 2 /O 2 flow ratio. The phenomenon of peak shift of Cu 2 O(1 1 1) implied that N atoms have been doped into Cu 2 O film. The square resistance of Cu 2 O:N films linearly decreased from 28.1 to 1.5 (10 4 Ω / ☐) with the increase of N 2 /O 2 flow ratio from 0.2 to 0.6 initially, and then it changed slowly with the increase of N 2 /O 2 flow ratio from 0.8 to 1.0. Hole density of Cu 2 O:N films with various N 2 /O 2 flow ratios from 0 to 0.6 was measured using the Van der Pauw method. All the samples are p -type, and the hole density of Cu 2 O:N films was enhanced from 1.2 × 10 16 cm −3 to 3.1 × 10 19 cm −3 with the increase of N 2 /O 2 flow ratio from 0 to 0.6. The experimental results demonstrated that N doping was an effective method to enhance hole density of p -type Cu 2 O film.

From soil to cave: Transport of trace metals by natural organic matter in karst dripwaters

This paper aims to establish evidence for the widespread existence of metal binding and transport by natural organic matter (NOM) in karst dripwaters, the imprint of which in speleothems may have important climatic significance. We studied the concentration of trace metals and organic carbon (OC) in sequentially filtered dripwaters and soil leachates from three contrasting sites: Poole's Cavern (Derbyshire, UK), Lower Balls Green Mine (Gloucestershire, UK) and Grotta di Ernesto (Trentino, Italy). The size-distribution of metals in the three soils was highly similar, but distinct from that found in fractionated dripwaters: surface-reactive metals were concentrated in the coarse fraction (>100nm) of soils, but in the fine colloidal (<100nm) and nominally dissolved (<1nm) fractions of dripwaters. The concentration of Cu, Ni and Co in dripwater samples across all sites were well correlated (R2=0.84 and 0.70, Cu vs. Ni, Cu vs. Co, respectively), indicating a common association. Furthermore, metal ratios (Cu:Ni, Cu:Co) were consistent with NICA-Donnan n1 humic binding affinity ratios for these metals, consistent with a competitive hierarchy of binding affinity (Cu>Ni>Co) for sites in colloidal or dissolved NOM. Large shifts in Cu:Ni in dripwaters coincided with high fluxes of particulate OC (following peak infiltration) and showed increased similarity to ratios in soils, diagnostic of qualitative changes in NOM supply (i.e. fresh inputs of more aromatic/hydrophobic soil organic matter (SOM) with Cu outcompeting Ni for suitable binding sites). Results indicate that at high-flows (i.e. where fracture-fed flow dominates) particulates and colloids migrate at similar rates, whereas, in slow seepage-flow dripwaters, particulates (>1μm) and small colloids (1–100nm) decouple, resulting in two distinct modes of NOM–metal transport: high-flux and low-flux. At the hyperalkaline drip site PE1 (in Poole's Cavern), high-fluxes of metals (Cu, Ni, Zn, Ti, Mn, Fe) and particulate NOM occurred in rapid, short-lived pulses following peak infiltration events, whereas low-fluxes of metals (Co and V>Cu, Ni and Ti) and fluorescent NOM (< ca. 100nm) were offset from infiltration events, probably because small organic colloids (1–100nm) and solutes (<1nm) were slower to migate through the porous matrix than particulates. These results demonstrate the widespread occurrence of both colloidal and particulate NOM–metal transport in cave dripwaters and the importance of karst hydrology in affecting the breakthrough times of different species. Constraints imposed by soil processes (colloid/particle release), direct contributions of metals and NOM from rainfall, and flow-routing (colloid/particle migration) are expected to determine the strength of correlations between NOM-transported metals in speleothems and climatic signals. Changes in trace metal ratios (e.g. Cu:Ni) in speleothems may encode information on NOM composition, potentially aiding in targeting of compound-specific investigations and for the assessment of changes in the quality of soil organic matter.

Photoluminescence Characterization and Passivation of CIGS Absorber

The photoluminescence is used to monitor the optical property of the Cu(In,Ga)Se2 solar cell. The temperature dependent external quantum efficiency shows the influence of defects in optical response and the band gap shift of Cu(In,Ga)Se2 at elevated temperature. The emission peaks at 1.03 and 1.1 eV are due to electrons in conduction band edge and donor state to recombine with holes in acceptor state, respectively. Competitiveness of these two transition mechanisms is studied with different pumping power and varied temperature by photoluminescence. The defect level and relative defect density can be obtained by the transition models. The Al2O3 is used to passivate the surface of CIGS absorber and enhance the photoluminescence intensity.

Investigation of anomalous physical properties of multilayer nanolaminate (TiAl)N/Cu coatings by electron spectroscopy techniques

AbstractIn accordance with high‐resolution transmission electron microscopy (HRTEM), (Ti34Al66)N/Cu physical vapour deposition (PVD) composite coating had a nanolaminated structure with 20 nm (Ti34Al66)N and 2.0–5.0 nm fine grain recrystallized Cu layers. It was unexpectedly found that the coatings under investigation had a lower thermal conductivity coefficient of 25 to 450 °C compared to the TiAlN single layer coating. The physical basis of thermo‐barrier protective features of copper nanolayers was explained based on XPS and high‐resolution electron energy losses spectroscopy (HREELS) data. The temperature dependence of the phonons and conducting electron vibrations was investigated for Cu bulk, (TiAl)N upper layer, and the intermediate Cu one. In comparison with Cu bulk reference sample, the intermediate Cu layers of complex PVD coating were characterized by the following features: size‐dependent shift of Cu 2p3/2 binding energy, reduced plasmon losses and acoustic mode phonon vibrations amplitudes, and increased intensities of the optical mode vibrations. These features of phonon and plasmon oscillations in the crystal lattice of Cu nanolayers do not completely explain the anomalies of the thermal conductivity of the (TiAl)N/Cu PVD coating. The thermal barrier properties of Cu nanolayers can be primarily attributed to the mirror effect or reflecting of the heat flux from the surface by metal layer with high concentration of conducting electrons. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Formation of a narrow chiral cavity in bis-copper(ii) complexes of ferrocenylmethyl-l-tyrosine and its interaction with achiral guests

Earlier we reported the tendency of ferrocenylmethyl substituted amino acids to organize around Cu(ii) in a C(2) symmetry. In this paper we have utilized this property to form a chiral cavity using a l-tyrosine derivative. Structural characterization of [Cu(II)(S-fTyr)(2)(MeCN)(2)] (), where S-fTyr(1-) is ferrocenylmethyl-l-tyrosinate, showed that the alignment of two tyrosine aromatic rings around the fifth coordination site generates a narrow cavity. Structural characterization of [Cu(S-fTyr)(2)(pyrazine)] (), [Cu(S-fTyr)(2)(pyridine)] (), [Cu(S-fTyr)(2)(bpy)] () and [Cu(S-fTyr)(2)(H(2)O)] () revealed that planar heterocyclic N-donors as guests stabilized the cavity, while polar water molecules destroyed it. Electrochemical properties of the complexes showed a shift of Cu(II)/Cu(I) potentials depending on the strength of the guest binding inside the cavity.

Molecular structure and dynamics of off-center Cu2+ ions and strongly coupled Cu2+–Cu2+ pairs in BaF2 crystals: Electron paramagnetic resonance and electron spin relaxation studies

X-band and Q-band electron paramagnetic resonance (EPR) spectra of Cu(2+) in BaF(2) crystal were recorded in the temperature range of 4.2-200 K. Spin-Hamiltonian parameters of single Cu(2+) complexes and of Cu(2+)-Cu(2+) pairs were derived and discussed. A special attention was paid to the dimeric species. Their molecular ground state configuration was found as having antiferromagnetic intradimer coupling with the singlet-triplet splitting J=-35 cm(-1). The zero-field splitting being D=0.0365 cm(-1) at 4.2 K increases with temperature as an effect of thermal population of excited dimer configurations. Electron spin echo (ESE) method was used for measurements of electron spin lattice and phase relaxation. The spin-lattice relaxation data show that except for coupling to the host lattice phonons the Cu(2+) ions are involved in local mode motions with energy of 82 cm(-1). Phase relaxation (ESE dephasing) of single Cu(2+) ions is due to spin diffusion at low temperatures. This relaxation is hampered for temperatures higher than 30 K due to the triplet state population of neighboring Cu(2+)-Cu(2+) dimers, which disturb dipolar coupling between Cu(2+) ions. For higher temperatures the relaxation is dominated by Raman T(1) processes. Fourier transform ESE spectrum displays dipolar Cu-F splitting which allowed determination of the off-center shift of Cu(2+) as delta(s)=0.132 nm. The dynamical effects observed in EPR spectra and in electron spin relaxation both for single Cu(2+) ions and Cu(2+)-Cu(2+) pairs are discussed as due to jumps between six off-center positions in the crystal unit cell and jumps between various dimer configurations.

Cu NMR study in a heavy-electron system, [formula omitted

Cu NMR measurements have been carried out for CaCu 3 Ru 4 O 12 , which shows a heavy-fermion-like behavior although it possesses no f electron moment. The field-sweep spectrum observed can be understood as a powder pattern of a Cu nucleus affected by the quadrupole interaction with no axial symmetry. The quadrupole parameters and the Knight shift of Cu are evaluated.

Interactions of adsorbed albumin with underpotentially deposited copper on gold piezoelectrodes

The adsorption of a model protein, bovine serum albumin (BSA), on Au electrodes was investigated using the Cu adatom probe method and Electrochemical Quartz Crystal Nanobalance (EQCN) technique. The adsorption of BSA was confirmed by AFM imaging and has been found to be controlled by kinetics. Using the Cu adatom probe method, we were able to reconstruct the entire BSA adsorption transient Θ BSA vs. t. The adsorption rate constant k 1, determined from this transient is k 1 = 2.45 × 10 5 L mol − 1 s − 1 . We have found that the bulk Cu 0 deposition process is blocked by BSA adsorption and it decays exponentially with time during BSA adsorption. It ceases completely when a full monolayer of BSA is formed. In contrast to that, the mass associated with Cu-u.p.d. decreases only to ca. 50% of that in the absence of BSA, indicating that Cu adatoms can penetrate (wedge) into the space between the surface Au atoms and the adsorbed BSA molecules. In addition to that, we have found that the degree of penetration of Cu adatoms can be controlled by the applied deposition potential. By selecting a sufficiently cathodic potential, we were able to deposit a full Cu-u.p.d. monolayer, independent of the BSA surface coverage extending from Θ BSA = 0 to Θ BSA ≈ 1. The positive shift of Cu ad desorption peak potential E p, observed in the presence of adsorbed BSA, has been interpreted in terms of Frumkin exchange interaction forces between Cu ad and BSA ad, on the basis of our earlier theoretical model, expanded here to include adsorbed species in two monolayers. This expansion is possible owing to the fast rate of Cu adatom penetration in the interfacial region. From the plots of E p vs. Θ BSA, the presence of strong attractive interactions between Cu ad and BSA ad was deduced. These interactions result in a super-shift of the Cu-u.p.d. desorption peak potential, corresponding to the exchange interaction coefficient g M,X < − 4, indicating on a possibility of the formation of a stable interface complex.

Relationship between the electronic structure of embedded single to triple atomic monolayers and bulk alloys

The relation between the electronic structure of thin film nanosandwiches and bulk alloys has been investigated by means of first-principles electronic structure theory. The spin magnetization, layered projected spectral properties, and interface core-level shifts of Cu, Ni, Co, and Fe systems have been calculated. In order to compare thin films to bulk alloys, systems with equal average nearest-neighbor coordination have been compared. We find that the spin magnetization and interface core level shifts are closely related to bulk with the exception of the core level shifts in the $\mathrm{Fe}∕\mathrm{Cu}$ multilayers, which are more sensitive to the specific structure of the thin film geometry. The discrepancy is discussed in terms of interacting interface states in the Cu spacer. The experimental possibility of detecting embedded monolayers is also investigated.

Zn and Cu isotopic variability in the Alexandrinka volcanic-hosted massive sulphide (VHMS) ore deposit, Urals, Russia

Copper and Zn isotope ratios of well-characterized samples from three ore facies in the Devonian Alexandrinka volcanic-hosted massive sulphide (VHMS) deposit, southern Urals, were measured using multi collector ICP-MS (MC-ICP-MS) and show variations linked to depositional environment and mineralogy. The samples analysed derived from: a) hydrothermal–metasomatic vein stockwork, b) a hydrothermal vent chimney, and c) reworked clastic sulphides. As the deposit has not been significantly deformed or metamorphosed after its formation, it represents a pristine example of ancient seafloor mineralization. Variations in δ 65Cu (where δ 65Cu = [( 65Cu / 63Cu) sample / ( 65Cu / 63Cu) standard − 1] * 1000) and δ 66Zn (where δ 66Zn = [( 66Zn / 64Zn) sample / ( 66Zn / 64Zn) standard − 1] * 1000) of 0.63 and 0.66‰, respectively, are significantly greater than analytical uncertainty for both isotope ratios (± 0.07‰, 2 σ). Very limited isotopic fractionation is observed in primary Cu minerals from the stockwork and chimney, whereas the Zn isotopic composition of the stockwork varies significantly with the mineralogy. Chalcopyrite-bearing samples from the stockwork have lighter δ 66Zn by ∼ 0.4‰ relative to sphalerite dominated samples, which may be due to equilibrium partitioning of isotopically light Zn into chalcopyrite during its precipitation. δ 66Zn also showed significant variation in the chimney, with an enrichment in heavy isotopes toward the chimney rim of ∼ 0.26‰, which may be caused by changing temperature (hence fractionation factor), or Raleigh distillation. Post-depositional seafloor oxidative dissolution and re-precipitation in the clastic sediments, possibly coupled with leaching, led to systematic negative shifts in Cu and Zn isotope compositions relative to the primary sulphides. Copper shows the most pronounced fractionation, consistent with the reduction of Cu(II) to Cu(I) during supergene mineralization. However, the restricted range in δ 65Cu is unlike modern sulphides at mid oceanic ridges where a large range of Cu isotope, of up to 3‰ has been observed [ Rouxel, O., Fouquet, Y., Ludden, J.N., 2004. Copper isotope systematics of the Lucky Strike, Rainbow, and Logatchev sea-floor hydrothermal fields on the Mid-Atlantic Ridge. Econ. Geol. 99, 585–600; Zhu, X.K., O'Nions, R.K., Guo, Y., Belshaw, N.S., Rickard, D., 2000. Determination of natural Cu-isotope variation by plasma source mass spectrometry: implications for use as geochemical tracers. Chem. Geol. 163, 139–149].

Surface oxidation of CVT-grown CuAlSe2

CuAlSe2 single crystals grown by chemical vapor transport (CVT) were plate-like and transparent ones with yellowish color and well-developed (112) surface. It was found that light transmittance of the crystals decreased with passing days after growth. The surface state of grown crystals was examined in detail by XPS method to clarify the cause and the following results were obtained. Chemical shift of Cu due to CuO and CuSe bonds was clearly observed and this suggests that the surface is oxidized at room temperature in air. The oxidation of the surface stopped after about 2 weeks and the thickness was about 0.6–2.2 μm. It was found that Al, one of the constituent elements of the compound, was lacking near surface region due to high reactivity of the element.