ISSN:0005-9021    

DOI:10.1002/bbpc.19830870602

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870603

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY

摘要:

AbstractThe adsorption of carbon monoxide and of hydrogen on evaporated iron films is studied by means of ultra violet photoelectron spectroscopy (UPS) and X‐ray photoelectron spectroscopy (XPS). Both methods indicate that carbon monoxide begins to decompose at 298 K. At 423 K the decomposition is complete. UP spectra of co‐adsorbed hydrogen and carbon monoxide confirm the existence of an interaction between these two gases in the adsorption layer at 298 K. The results are used to correlate earlier thermodynamic and kinetic studies with known literature data about photoelectron spectra of the systems Fe/H2, CO and to discuss the influence of crystal orientation and surface structure on the adsorption of H2and CO on

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870604

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY

摘要:

AbstractA highly reactive cadmium deposit is formed, when colloidal cadmium sulfide is illuminated in the presence of sulfite or dithionite anions (10−4−10−3M). It is oxidized by oxygen, nitrous oxide, hydrogen ions and methylviologen. The quantum yield amounts to 0.005 in the absence of excess cadmium ions. In the presence of 5 · 10−4Cd2+ions, the quantum yield is 0.053. The rate of cadmium formation was investigated as a function of the excess Cd2+concentration, sulfite concentration and the pH. The effects are explained in terms of the formation of electrons and positive holes upon illumination, scavenging of the holes by adsorbed sulfite anions and reaction of the excess electrons with Cd2+ions. The sulfite anions react mainly in an one‐hole oxidation process yielding SO 3−radicals that form SO 42−and S2O 62−via the respective disproportionations and combinations. The deposition of cadmium metal was also observed in the illumination of CdS powder suspended in a 1 M sulfite solution. In the beginning of the illumination Cd was formed, later on hydrogen was generated. These effects are explained in terms of a large overpotential for the reduction of water by excess electrons in CdS and the catalytic action of a cadmium layer. — Cadmium metal is formed with practically 100% efficiency when colloidal CdS solutions are γ‐irradiated in the presence of suitable organic additives. This effect is attributed to the transfer of electrons from reducing organic radicals

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870605

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY

摘要:

Abstract1H NMR was studied in thin foils of β‐NbHx(0.71 ≦x≦ 0.86). Three1H NMR signals, A, B, and C have been observed. Their chemical shift depends on the hydrogen concentrationx. The separation of the signals is several ten ppm. A strong dependence of the signal intensity from the pretreatment of the metal foil is found. It is shown that the signal A is most probably due to hydrogen atoms trapped at dislocations and domain boundaries. Signal B belongs to the1H NMR in the undisturbed lattice of β‐NbHx. Finally signal C is possibly due to hydrogen trapped at interstitial oxygen i

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870606

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY

摘要:

AbstractKinetic aspects of the solid state reaction between the binary semiconductors CdTe and HgSe as well as the topochemistry of the reaction zone are investigated by an electron microprobe and by optical microscopy. The reaction path is markedly influenced by intrinsic doping of the binary reaction components. Pronounced regions of uphill diffusion of chalcogens or of metals are essential features of the reaction behaviour in this semiconductor alloy system.

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870607

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY

摘要:

AbstractWe have measured the thermal conductivity, λ, of n‐undecane, using the transient hot‐wire technique. At low pressures, n‐undecane has a plastic crystal phase αH. The increase in λ, going from the liquid to phase αH, was 35%. For a liquid → plastic crystal transition, this is a high value. It reflects that orientational disorder is mainly limited to rotation of the rod‐shaped molecule around its chain axis. The low temperature phase βO, was shown to exhibit a weak temperature dependence of λ at isochoric conditions. This suggests the presence of structural disorder, probably caused by reorientation of the chain‐end methyl groups. The volume dependence of λ in phase βO,g= ‐(∂ln λ/∂lnV)T, was found to be about 9.5. This result is discussed in terms of the anharmonicity of the weak interchain van der Waal's bonds. Some heat capacity

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870608

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY

摘要:

AbstractElectrical conductivity in magnetite has been studied experimentally as a function of temperature and oxygen activity between 560 and 1400°C. The results indicate that aboveTC(=575°C) an octahedral site small polaron mechanism is dominant over the entire temperature range (Ea= 0.1136 eV). By comparing data on electrical conductivity and thermoelectric power, a second (small polaron) mechanism (Ea= 0.714 eV) is detected at elevated temperatures. Additionally, equilibrium constants for the cation vacancy formation are derived from fitting the conductivity isotherms as a function of oxygen activity. These agree well with values determined thermogravimetricall

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870609

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY

摘要:

AbstractThe clusters Lik(k= 3–8), Na4, K4, Bex(x= 3–13), Mgy, Cay, Aly(y= 3–5) and Gez(z= 3–6) are investigated employing the ab initio CI method. — The bond in alkali metal clusters is due to the interaction of the outer s orbitals but p polarization functions are essential for a correct prediction of the electronic structure and stability of possible geometries of these clusters. In alkaline earth metal clusters the role of sp hybridization is crucial for the appearance of attractive interactions. The most relevant factor determining the stability of Al and Ge clusters is the bonding between p atomic orbitals. The spin properties of small clusters, which are important for their stability, are determined by their geometry and symmetry. — The most stable clusters of elements which crystallize in compact structures (bcc, fcc and hcp) are always sections of the corresponding crystal lattices. On the contrary, the Ge clusters exhibiting large stability are not parts of the diamond lattice and can be considered as deformed parts of more compact lattices. — The binding energy per atom of Li and Be clusters qualitatively converges to the cohesive energy of the metals with the growth of the cluster size. — In the largest clusters the existence of very small singlet‐triplet energy splittings indicates the development of a m

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870610

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY

摘要:

AbstractSpecific and statistical solvation of Co(II)‐ions in mixtures of methanol with dimethylformamide respectively hexamethylphosphoric triamide was found by1H‐NMR‐spectroscopy. Relations are given, which correlate these possible solvation models with the kinetics of solvent exchange. On this basis, specific outersphere solvation of the methanol rich Co(II)‐solvate‐complexes by dimethylformamide can be deduced. For mixtures of hexamethylphosphoric triamide with methanol, the statistical solvation behaviour is additionally favoured by a strong solvent‐solvent

ISSN:0005-9021    

DOI:10.1002/bbpc.19830870611

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1983

数据来源: WILEY