Recombination coefficients in extrinsicn-InSb

The bulk recombination coefficients for linear recombination via recombination centers as well as for direct recombination have been determined measuring the conductivity decay after two-photon absorption with a CO₂ laser. The Suhl effect was applied to measure the surface recombination velocity. The corresponding literature is discussed and compared with our results. We conclude that two different kinds of recombination centers are possible inn-InSb, with energy levels (0.1–0.12) eV above the valence band, or (0.14–0.2) eV respectively.     

Ru(2) Bi(14) Br(4) ](AlCl(4) )(4) by Mobilization and Reorganization of Complex Clusters in Ionic Liquids

Two polymorphs of the new cluster compound [Ru(2) Bi(14) Br(4) ](AlCl(4) )(4) have been synthesized from Bi(24) Ru(3) Br(20) in the Lewis acidic ionic liquid [BMIM]Cl/AlCl(3) ([BMIM](+) : 1-n-butyl-3-methylimidazolium) at 140?°C. A large fragment of the precursor's structure, namely the [(Bi(8) )Ru(Bi(4) Br(4) )Ru(Bi(5) )](5+) cluster, dissolved as a whole and transformed into a closely related symmetrical [(Bi(5) )Ru(Bi(4) Br(4) )Ru(Bi(5) )](4+) cluster through structural conversion of a coordinating Bi(8) (2+) to a Bi(5) (+) polycation, while the remainder was left intact. Both modifications have monoclinic unit cells that comprise two formula units (α form: P2(1) /n, a=982.8(2), b=1793.2(4), c=1472.0(3)?pm, β=109.05(3)°; β form: P2(1) /n, a=1163.8(2), b=1442.7(3), c=1500.7(3), β=97.73(3)°). The [Ru(2) Bi(14) Br(4) ](4+) cluster can be regarded as a binuclear inorganic complex of two ruthenium(I) cations that are coordinated by terminal Bi(5) (+) square pyramids and a central Bi(4) Br(4) ring. The presence of a covalent Ru?Ru bond was established by molecular quantum chemical calculations utilizing real-space bonding indicator ELI-D. Structural similarity of the new and parent cluster suggests a structural reorganization or an exchange of the bismuth polycations as mechanisms of cluster formation. In this top-down approach a complex-structured unit formed at high temperature was made available for low-temperature use.     

Verhalten von Organochlorpesticiden bei der Extrakteinengung

Zusammenfassung Versuche zum Einengen von Lösungen und Extrakten von Organochlorpesticiden im Spurenbereich wurden mit dem Rotationsverdampfer durchgeführt. Wird normales Wasserstrahlvakuum benutzt, sind die Wiederfindungsraten nicht zufriedenstellend und die Schwankungen der Einzelversuche um den Mittelwert zu groß. Abhilfe kann man mit einem Vakuum-Controller schaffen. Die Ergebnisse dieser Versuche sind besonders für spurenanalytische Bestimmungen und für die richtige Wahl der Kalibrierart wichtig.

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Behaviour of organochloropesticides in extract evaporation

Summary Experiments were carried out to evaporate solutions and extracts of organochloropesticides in trace analysis with a rotary evaporator. Recoveries and scattering of single values around the mean were not satisfactory if evacuation was done by normal water-jet vacuum. Better results were obtained by application of a vacuum-controller. The experiments are important both for trace analysis determinations and the right choice of the calibration mode.

     

Beiträge zur Untersuchung anorganischer nichtstöchiometrischer Verbindungen. XX. Metastabile Oxydation von Mischkristallreihen — ein Zugang zu W-reichen Blockstrukturen im System Nb2O5/WO3

Contributions to the Investigation of Inorganic Non-stoichiometric Compounds. XX. Metastable Oxidation of a Series of Solid Solutions — an Access to W-rich Block Structures in the System Nb₂O₅/WO₃ The characteristical region of existence of block structures with building elements that are limited in size in two directions ends in the system Nb₂O₅/WO₃, as was shown by previous investigations, under conditions of equilibrium at a maximum value of 2.654 O/ΣM. For the occurring phases with the ratios Nb₂O₅: WO₃ = 6:1, = 7:3, = 8:5 and = 9:8 as well we now were successful in substituting W for Nb. The original block structure and the corresponding ratio O/ΣM were preserved. The “9:8”-phase W_4/4[Nb₁₈W₇O₆₉], for example, forms solid solutions W_4/4[Nb₁₁W₁₄O₆₉] leaving the size of the building elements ([5 times; 5] blocks) unchanged. Hereby the ratio W/Nb is drastically enhanced from 0.444 to 1.364. By metastable oxidation of these solid solutions at temperatures of about 500°C, for instance in air, one comes back to the system Nb₂O₅/WO₃. In this way the region of existence of block structures could be expanded far beyond the limit at 2.654 O/ΣM to higher W/Nb values.