On the stoichiometry of the organic metal bis(ethylenedioxy)-tetrathiafulvalene chloride

We report on Shubnikov-de Haas and de Haas-van Alphen measurements of an organic metal based on the molecular donor bis(ethylenedioxy)-tetrathiavulvalene (= BEDO-TTF) and the anion Cl^- with H₂O molecules. The observed single oscillation frequency perfectly follows the two-dimensional dependence with T. The Fermi-surface area of of the first Brillouin zone proves a quarter-filled band, i.e., a 2:1 stoichiometry of the BEDO-TTF donor with respect to the anion. The apparent discrepancy to X-ray data which give a 1:1 ratio between BEDO-TTF and Cl^- is understood by replacement of H₂O molecules with (H₃O)⁺ ions. The proposed stoichiometry therefore is (BEDO-TTF)₂ ⁺(H₅O₂)⁺(Cl^-)₂. The cyclotron effective mass is when deduced from the temperature dependence of the fundamental oscillation amplitude, but strongly reduced when extracted from higher harmonics. This and the strong harmonic content of the oscillations signals an influence of the two-dimensional electronic structure and can be qualitatively understood by applying the concept of magnetic interaction to the effect of the oscillatory chemical potential. Received: 16 April 1998 / Revised: 7 July 1998 / Accepted: 9 July 1998     

Zum schnellen Nachweis von Bromiden in Alkalijodiden

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The photoelectron spectra of gaseous zinc(II) and cadmium(II) chlorides,bromides, and iodides

The He I photoelectron spectra of the gaseous chlorides, bromides, and iodides of zinc(II) and cadmium(II) have been obtained using a high-temperature spectrometer equipped with an internally-located, laser-beam heated, sample oven. The spectral peaks have been assigned molecular-orbital origins by use of qualitatively-derived molecular-orbital diagrams.     

The anisotropy of conductivity of n-type germanium in strong d.c. fields

The electric conductivity ofn-type germanium at large d.c. field intensities has been measured in three directions of symmetry of the cubic lattice. From these data the repopulation of valleys of the conduction band has been determined. Measurements were done with three materials of different purity. The variation of repopulation between these materials can be explained qualitatively by the influence of Coulomb scattering at ionized impurities. The data are compared with those ofNathan and theoretical data ofFranz andReik et al. The relations of these data to those of the current component perpendicular to the field direction (Sasaki et al.) are also given.     

Eisen, Stahl

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Titan

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Eisen

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