Synthese und Kristallstruktur von (PPh4)2[Mo2(S2)2Cl8] · 2 CH3CN und seine topotaktische Umwandlung zu (PPh4)2[Mo2(S2)2Cl8]

Synthesis and Crystal Structure of (PPh₄)₂[Mo₂(S₂)₂Cl₈] · 2 CH₃CN and its Topotactic Transformation to (PPh₄)₂[Mo₂(S₂)₂Cl₈] MoS₂Cl₃ was prepared from molybdenum and S₂Cl₂ at 200 °C. Its reaction with PPh₄Cl in acetonitrile yielded (PPh₄)₂[Mo₂(S₂)₂Cl₈] · 2 CH₃CN. In vacuum or upon warming, it loses the acetronitrile without degradation of the crystals. According to the X-ray crystal structure determinations both compounds, with and without acetonitrile, are triclinic. They contain the same [Cl₄Mo(μ-S₂)₂MoCl₄]^2– ions, in which the Mo atoms are joined by two disulfido groups and an Mo–Mo bond. Details of the crystal packings and their topotactic transformation are given.     

A Poly(para-phenylene) with Hydrophobic and Hydrophilic Dendrons: Prototype of an Amphiphilic Cylinder with the Potential to Segregate Lengthwise

Langmuir monolayers are formed from an amphiphilically decorated poly(para-phenylene), which indicates that its hydrophilic and hydrophobic parts segregate lengthwise along the polymer backbone in this nanometer-sized cylinder as illustrated in A . This polymer differs from known amphiphiles in that it consists of a linear, covalently bound sequence of “little” amphiphiles. It is much more rigid than common “polysoaps”, which should increase its potential to aggregate, for example, into channels.     

Quantitative determination of contact stiffness using atomic force acoustic microscopy

Atomic force acoustic microscopy is a near-field technique which combines the ability of ultrasonics to image elastic properties with the high lateral resolution of scanning probe microscopes. We present a technique to measure the contact stiffness and the Young's modulus of sample surfaces quantitatively, with a resolution of approximately 20 nm, exploiting the contact resonance frequencies of standard cantilevers used in atomic force microscopy. The Young's modulus of nanocrystalline ferrite films has been measured as a function of oxidation temperature. Furthermore, images showing the domain structure of piezoelectric lead zirconate titanate ceramics have been taken.     

Δ++π−-electroproduction near threshold and the Q2 dependence of the contact interaction

The Q² dependence of σ (γvp→π^?Δ⁺⁺) was measured. Close to threshold σ (γvp→π^?Δ⁺⁺) is roughly proportional to 1/(m²_? + Q²)². The data are consistent with dominance of the contact term and imply that the contact term has the Q² dependence of the ? propagator.     

Binary phase gratings for star couplers with high splitting ratio

Binary phase transmission gratings exhibiting a certain number N of central diffraction orders of equal intensity can be used to construct star couplers of the 1-to-N and N-to-N type. The calculation of the grating's groove structure is described, and first experimental results are presented.     

Parallel and time sequential optical multiplex systems for pattern recognition

Two optical multiplex arrangements for pattern recognition are compared. In the first system the Fourier spectrum of an object transparency is optically multiplied for parallel processing with a matrix of different holographic Fourier filters. In the other arrangement the spectrum of the object transparency is switched time sequentially by means of a light beam deflector onto different filters in the Fourier plane. In comparison the time sequential method appears better adapted for high information content.     

Darstellung und Eigenschaften von Kupfer(II)-Hypophosphit

Thermal Behaviour of the Mixtures Na₂S? P₄S₁₀ and Na₄Ge₄S₁₀? P₄S₁₀ of the System Na₂S? GeS₂? P₄S₁₀ The mixtures of Na₂S? P₄S₁₀ and Na₄Ge₄S₁₀? P₄S₁₀ were investigated by DTA and DSC. In the system Na₂S? P₄S₁₀ the congruently melting compounds Na₃PS₄ and (NaPS₃)_x and the peritectic phase Na₄P₂S₇ were found. The IR-spectra are given. Glassy, anhydrous and hydrated Na₄Ge₄S_l0 were prepared and thermochemically characterized. The section Na₄Ge₄S₁₀? P₄S₁₀ is not quasibinary, the mixed cage-anion Ge_4?xP_xS₁₀^(4?x)? thus cannot be prepared by heating and annealing mixtures of Na₄Ge₄S₁₀ and P₄S₁₀.