Synthesis of E-(1,3-butadienyl)malonate from E-diethyl (2-butenylidene)malonate using dimethylsulfonium methylide

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2872–2873, December, 1989.     

Induced refractive index in thin films of polymeric organosilanes under UV irradiation

Changes in the refractive indices of thin films of three polymeric organosilanes at wavelengths of 400-1500 nm, occurring under UV radiation, were examined.     

Spectral and optical properties of high-optical-quality organic glasses under prolonged ultraviolet irradiation

The effect of prolonged UV irradiation on optical and spectral luminescent properties of two types of high-quality optical organic glasses are studied by electronic absorption spectroscopy, spectrofluorimetry, IR spectroscopy, and atomic force microscopy. Glasses 2.3 mm in thickness are obtained through the layer-by-layer photopolymerization of an oligo(epoxy diacrylate) mixture with benzyl methacrylate and oligo(carbonate dimethacrylate). After the addition of europium tris(benzoyltrifluoroacetonate) to the photopolymerizing compositions, glasses that luminesce in the red spectral region are produced. The action of light gives rise to a slow photodecomposition of the luminescent component and causes a decline in the intensity of the band due to ⁵ D ₀ → ⁷ F ₂ transition of the europium cation. The growth of absorption in the yellow-green spectral region favors formation of an internal light filter; as a result, the photodecomposition of the europium complex in deep layers proceeds at a smaller rate than that in surface layers. IR-spectroscopy measurements demonstrate the accumulation of hydroxyl groups in oligo(carbonate dimethacrylate) films during irradiation in air. In an inert atmosphere, practically no photodegradation products are evolved from the matrix material.     

Theoretical study of a magnetoresistive magnetic field transmitter with a ring sensor

Theoretical results are presented concerning the performance of thin-film anisotropic magnetoresistive magnetic field sensors with a single- and multilayered ring configuration. A mathematical model is proposed that allows analytical calculation of magnetization fields, is suitable for sensor optimization, and requires a reasonable amount of computing time. A system of equations is derived for the magnetization angle of rotation. On this basis, the response, sensitivity, and angular characteristics of particular sensors are optimized.     

Crystal lattice defects and Hall mobility of electrons in Si: Er/Si layers grown by sublimation molecular-beam epitaxy

The density of crystal lattice defects in Si: Er layers grown through sublimation molecular-beam epitaxy at temperatures ranging from 520 to 580°C is investigated by a metallographic method, and the Hall mobility of electrons in these layers is determined. It is found that the introduction of erbium at a concentration of up to ～5 × 10¹⁸ cm^?3 into silicon layers is not accompanied by an increase in the density of crystal lattice defects but leads to a considerable decrease in the electron mobility.     

Magnetic and magnetooptical properties of multilayer ferromagnet-semiconductor nanostructures

The magnetic and magnetooptical properties of spin-tunneling multilayer permalloy-silicon carbide nanoheterostructures deposited by rf sputtering have been studied. Magnetometric and magnetooptical methods are used to show that the magnetic-semiconducting nanostructures have a complex magnetic structure and to track the evolution of the magnetic properties of these structures as functions of the magnetizing field and the thickness and sequence order of ferromagnetic and semiconducting layers in them. The induction response and the field and orientation dependences of the transversal Kerr effect are found to have anomalies. The experimental results are interpreted under the assumption that there is exchange interaction between the ferromagnetic and semiconducting layers through a thin magnetically ordered transition layer formed inside the interface.     

Insertions of silylated carbenoids into vinylzirconocene chlorides. A convergent route to silyl-substituted allylzirconium reagents

A convergent route to allylzirconocene reagents by insertion of silyl-substituted carbenoids LiCR(SiMe₃)(Cl) into vinylzirconocene chlorides is reported. The product silylated allylzirconocenes react with aldehydes and ketones with high anti-selectivity to afford vinyl- (R=H) or allyl- (R=Me, Pr) silanes which may be converted into 4,5-trans-disubstitituted γ-lactones and stereodefined dienes.