Copper, atomic structure

Magnussen O M, Hotios J, Beitei G, Koib D M and Behm R J 1991 Atomic structure of ordered copper adiayers on singie-crystaiiine goid eiectrodes J. Vac. Sc/. Technol. B 9 969... 

The effect of surface electrostatic charge on a material on the attachment of the decay products of radon has been known since pioneering work on atomic structure by Rutherford. Extensive research into this area for the radon and thoron progeny has been conducted in this laboratory for environmental monitoring purposes. Several authors have reported on the effect of electrostatic charge on the collecting characteristics of copper for the radon progeny for exploration purposes (Card and Bell, 1979). 

For examining atomic structures with bond lengths of 1-2 A, the interrogating beams ideally should have wavelengths of the same dimensions, to resolve atomic details. X-rays fulfill this criterion because their wavelength, for example, CuK (X-ray using copper target) is 1.5418 A (1.5418 x 10 m), which is similar to atomic dimensions. 

Figure 1 Relationship between the perovskite structure ABOs (left) and the defect-perovskite superconductor YBajCugOy (right). Metal atoms are shaded. Note the missing oxygen atoms in the latter drawing that result in formation of copper-oxygen sheets (above and below the Y atoms), and copper-oxygen chains (between the Ba atoms).

The cuprite (CujO) structure consists of a body-centred cubic array of oxygen the copper atoms occupy centres of four of the eight cubelets into which the BCC cell may be divided (Fig. 1.7). In this structure, copper has a linear coordination and oxygen tetrahedral coordination (2 4). This structure is unique among inorganic materials in that it consists of two identical interpenetrating frameworks which are not directly linked to each other. 

The enthalpy of atomization of copper does not differ at all for the two compounds, and the atomization of chlorine adds only a small difference for the second mole of chlorine. The major energy cost for CuCl2 is the second ionization energy of copper which is compensated by the electron affinity to form the second chloride ion and especially the lattice energy. Since the electron ionized to form Cu2 is a d electron and does not break a noble gas structure, IE2 is not excessive, and both CuCl and CuCl2 are stable compounds. 

The CuA center has an unusual structure.130-132 It was thought to be a single atom of copper until the three-dimensional structure revealed a dimetal center, whose structure follows. The CuB-cytochrome a3 center is also unusual. A histidine ring is covalently attached to tyrosine.133-1353 Like the tyrosine in the active site of galactose oxidase (Figs. 16-29,16-30), which carries a covalently joined cysteine, that of cytochrome oxidase may be a site of tyrosyl radical formation.135... 

Table 16 The Frequency of Occurrence of Donor Atoms in Copper(I) Complexes of Known Crystal Structure...

In this contribution, we will first provide an overview of the nature of the systems and phenomena and the modeling and computational challenge which they represent. In the following two sections we describe calculations of the electronic and atomic structure of the interface and of electron transfer at the interface. In each case we present some details of our own results involving copper-water interfaces and electron transfer from a copper ion in... 

Figure 8.17 Left Schematic of a scanning tunneling microscope (STM). Right STM image (2.7 x 2.7 nm) of the atomic structure of a copper (111) surface imaged in an aqueous medium after electrochemical cleaning [357]. The image was kindly provided by P. Broekmann and K. Wandelt.

When we determined the crystalline structure of solids in Chapter 4, we noted that most transitional metals form crystals with atoms in a close-packed hexagonal structure, face-centered cubic structure, or body-centered cubic arrangement. In the body-centered cubic structure, the spheres take up almost as much space as in the close-packed hexagonal structure. Many of the metals used to make alloys used for jewelry, such as nickel, copper, zinc, silver, gold, platinum, and lead, have face-centered cubic crystalline structures. Perhaps their similar crystalline structures promote an ease in forming alloys. In sterling silver, an atom of copper can fit nicely beside an atom of silver in the crystalline structure. 

The initial product of the copper reaction is a brown precipitate of stoichiometry Cu(p-tol-NNNNN-tol-p)2, which, on heating, is reduced to deep red, air-stable Cu(p-tol-NNNNN-tol-p) j. The latter product, which is weakly paramagnetic [p ranges from 0.33 (113 K) to 1.52 BM (303 K)] and decomposes explosively at 160°C, has been found by X-ray diffraction methods to possess the trinuclear structure shown in Fig. 18. Three N, zig-zag chains coordinate three linearly arranged copper(I) ions through N-1, N-3, and N-5 atoms, such that each copper is in a trigonal-planar coordination environment. Mean copper-nitrogen distances are 2.036 A for the outer copper atoms and 1.945 A for the central copper atom. The copper-copper distances of 2.348 and 2.358 A are the shortest yet recorded for copper(I) complexes (6). 

Ceruloplasmin is an enzyme synthesised in the liver which contains six atoms of copper in its structure. Ceruloplasmin carries 90% of plasma copper the other 10% is carried by albumin. Ceruloplasmin exhibits a copper-dependent oxidase activity, which is associated with possible oxidation of Fe + (ferrous iron) into Fe (ferric iron), therefore assisting in its transport in the plasma in association with transferrin, which can only carry iron in the ferric state. 

SUPERCHAINS AND PLANES. The atomic structure of ceramic superconductors contains chains and planes of copper and oxygen atoms. Both chains and planes appear to contribute to high-temperature superconductivity in some of the new materials. (Courtesy Argonne National Laboratory.)... 

With the use of the DV-Xa molecular orbital method, electronic structure calculations have been performed to investigate the impurity effect on material properties. Firstly, calculations were done for F atoms substituted for 0 (oxygen) atoms in copper oxide superconductors. It was found that the population of the atomic orbitals of F atoms is small in HOMO (highest occupied molecular orbital) and a small fraction of charge carriers enters the impurity sites. The F impurities are therefore expected to be effective for pinning magnetic flux lines in Cu oxide superconductors. 

EPR spectra recorded for solutions of different pH were simulated on the basis of the assumption of coordination spheres with different compositions and structures. These measurements indicated the coordination of one N donor atom to copper(II) at pH > 6 in MLH.2, and dimerization of the complex between pH 6 and 10 (M2L2H 4, M2L2H.3). The EPR spectra also reflected the decomposition of the dimeric species at pH > 10, i.e. the formation of MLH.3. 

The substance copper crystallizes with this structure because of the tendency of each atom of this metal to attract to itself as many other atoms of copper as can find room about it. The forces which attract atoms to one another and hold them together strongly (the valence forces, Chaps. 10 and 11) are said to give rise to the formation of chemical bonds between these atoms. These forces are due to the electrical interaction of the electrons and nuclei of the atoms, and the nature of the chemical bonds isdiich an atom can form is determined by the electronic structure of the atom. 

In Figure 4-6 there is shown the atomic structure of the gold-copper alloy used in jewelry. This material consists of small crystal grains, held firmly together by the interatomic forces between them, each grain... 

The structure of covelline, CuS, is more complicated than would be anticipated from its simple stoichiometric formula. In this crystal there are two types of sulphur atoms, the Sg groups located between six copper atoms as in pyrites and, in addition, isolated atoms of sulphur surrounded by five atoms of copper, three in the form of a triangle at a distance of 2 19 A and two, one above and one below, at a distance of 2 35A. The copper atoms are also arranged in different ways, some being located at the centres of tetrahedra and others at the centres of triangles of sulphur atoms. In view of this complex structure the formula GU3SS2 has been suggested. The PtS crystal possesses a similar structure to the PtO crystal. 

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