Buchbesprechungen

Ohne Zusammenfassung     

P2J3 – ein neuartiger Komplexligand

P₂J₃ – a New Complex Ligand P₂J₄ and Na₂Cr(CO)₅ react in benzene to the monomeric diamagnetic complex (CO)₄CrP₂J₃. The ³¹P-nmr spectrum shows the presence of different bonded phosphorus atoms. The exchange of one iodine atom between the P atoms leads to a temperature dependent equilibrium with a symmetrical transition state. Triphenyl- and tricyclohexylphosphine react with (CO)₄CrP₂J₃ to (CO)₄CrPJ₂ · P(C₆H₅)₃ resp. (CO)₄CrPJ₂ · P(C₆H₁₁)₃, probably of dimeric nature.     

Hydrolysis equilibrium of phenylbutazone (Butazolidin)

Phenylbutazone (I) forms in aqueous and partially aqueous solution butylmalonic acid mono (N, N′-diphenylhydrazide) (II) by a reversible reaction. The reaction rate and the position of equilibrium depend on the solvent but practically not on the pH. The temperature dependence is given for several media. Substituents affect the reaction rate when they are in 4-position but not in 4′- or 4″-position. Based on the kinetic data, a reaction mechanism is proposed. Methods for the analysis of I in mixtures with II are presented. The preparation of II is described.     

On the influence of lattice vibrations on the tunnel-current in normal metals

Energy spectra of 50 kev-electrons scattered inelastically in thin Al foils of various thicknesses have been measured as a function of scattering angle. The measured angular distribution of electrons which have excited one or more volume plasmons is compared with theoretical calculations and good agreement is obtained. From the integrated intensities, the mean free path of 50 kev-electrons for plasmon excitation is determined with an accuracy of about 20%. The resulting value Λ=820 Å is in good agreement with the theoretical value calculated fromFerrell's free electron model (Λ=760Å).     

Excitation-induced absorption and luminescence at the GaSe exciton

Transmission changes induced by extremely high optical excitation at or below the fundamental direct exciton level of GaSe in the parallel geometry (light propagating parallel to the c-axis) are reported. A double-beam technique is used. The data show that no gain develops up to the highest pumping levels attainable. Careful luminescence measurements, taken concurrently, indicate that the observation of stimulated emission in such geometry, often reported in the literature, is a spurious effect. Optical amplification is possible in the transverse geometry, and is accompanied by the disappearance of discrete exciton levels, including the ground state. A continuous distribution is rather observed, which tails deep into the forbidden energy gap. The possibility of a final plasma state is discussed.     

Why is ϱ' photoproduction suppressed?

The experimentally observed ? and ?' photoproduction cross-sections can be explained in terms of a multiperipheral production mechanism and duality. The small value for the ratio of the Pomeron (P) couplings g_γP?' : g_γP? has no application for the ratio g_γ?' : g_γ?.     

The influence of correlations on the odd-mass Nuclei21Ne and25Mg

Excitation energies and electromagnetic properties of the low energy spectra of²¹Ne and²⁵Mg have been calculated using the Multi-Configuration-Hartree-Fock (MCHF) model. BothT=0 andT=1 pairing correlations are found to be simultaneously important in those odd mass nuclei. Furthermore, though axial symmetry was requested, quite good agreement with the experimental data is reached.     

Lokale Formationen endlicher Gruppen

Ohne Zusammenfassung