Schwefeleisen als L?throhrreagens

Ohne Zusammenfassung     

Molecular Origin of the Charge Carrier Mobility in Small Molecule Organic Semiconductors

Small‐molecule organic semiconductors are used in a wide spectrum of applications, ranging from organic light emitting diodes to organic photovoltaics. However, the low carrier mobility severely limits their potential, e.g., for large area devices. A number of factors determine mobility, such as molecular packing, electronic structure, dipole moment, and polarizability. Presently, quantitative ab initio models to assess the influence of these molecule‐dependent properties are lacking. Here, a multiscale model is presented, which provides an accurate prediction of experimental data over ten orders of magnitude in mobility, and allows for the decomposition of the carrier mobility into molecule‐specific quantities. Molecule‐specific quantitative measures are provided how two single molecule properties, the dependence of the orbital energy on conformation, and the dipole‐induced polarization determine mobility for hole‐transport materials. The availability of first‐principles based models to compute key performance characteristics of organic semiconductors may enable in silico screening of numerous chemical compounds for the development of highly efficient optoelectronic devices.     

Zur photochemischen (Z)⇆(E)-Isomerisierung von Gallenpigment-Partialstrukturen

The photochemical (Z)?(E) isomerization of the exocyclic double bond is only possible in pyrromethenones (partial structure1) but not in2–4. From spectral investigations, chelation and methylation of certain positions within these structures it can be shown that it is most probably a proton transfer reaction which competes successfully with the isomerization.     

采用遗传算法由电流环的近场测试识别辐射源

针对电大尺寸的电流环,通过遗传算法找到最佳等效基本辐射器.采用EMSCAN电磁干扰扫描系统进行电流环的近磁场测试,从而作出远场预测,并与仿真结果和半电波暗室的测试数据相比较.     

Temperature dependence of Bi2O3 structural parameters close to the α–δ phase transition

This article presents the results of in situ X-ray powder diffraction, Raman spectroscopy, and electrical impedance spectroscopy of the α-phase of Bi₂O₃, at 0.1 MPa in the temperature range below and above the α–δ-phase transition. This work demonstrated subtle nonlinear temperature variations of the cell parameters, of the hard-mode Raman shift, and of the activation energy of electrical conductivity in the temperature range about 100–120°C below the α–δ phase transition temperature T _Tr ≈ 725°C in Bi₂O₃. At T < 600°C, the linear variation of the inverse dielectric susceptibility (χ ^?1) correlates well with the hard mode frequency shift Δ(ω ²) of Raman A_1g mode as Δ(χ ^?1)/Δ(ω ²) ≈ 5.5 × 10^?7 cm². A structural model describing the mechanism of O^2? anion distribution and electric dipole disordering in the vicinity of T _Tr is discussed.     

Defined carrageenan derivatives as angiogenesis inhibitors

Three carrageenans derived from red algae and three partially modified carrageenans were tested for their ability to inhibit the formation of new blood capillaries on the chorionallantois membrane of the hen egg. It could be clearly demonstrated that they were better angiogenesis inhibitors than the standard compound suramin.     

Precision infrared spectroscopy in CF379Br by means of infrared-microwave double resonance

From the observation of double resonance effects on the microwave spectrum two coincidences between 9.4 μm CO₂ laser lines and infrared transitions of the ν₆ → (ν₆ + ν₁) band of CF₃⁷⁹Br have been determined: R(30) laser line coincident with ^qR₂(7), F = 17/2→17/2 transition, R(28) laser line coincident with all four ΔF = 0 hyperfine components of the ^qQ₈(13) transition. In both cases other infrared transitions lay within the tuning range of the laser. The frequencies of these two laser lines allowed calculations of the band center frequency ν₀ = 1083.530 ± 0.001cm^?1 and α_A = 11.93 ± 0.3MHz, for the ν₆ → (ν₆ + ν₁) band.α_B constants were determined for the vibrational states v₆, (v₆ + v₁), v₁, and v₃.