Conformational Transformations of ε-Caprolactam as an Advantage in the Production of Molecular Complexes Used in Adhesive Technology

The conformations of the ε-caprolactam molecule were calculated using a software package, and three of its conformers were established. It is shown that the conformational change of molecules creates the prerequisites for organizing the nearest contact and strong hydrogen bonds of ε-caprolactam with molecules of other substances. The molecule of ε-caprolactam can be “adapted to a neighbor” to a greater degree, since it can take a different, more advantageous conformation to provide the necessary contact. With the use of ε-caprolactam, molecular complexes have been obtained that have found application in the production of adhesives for rubber–cord systems.     

Two-dimensional electron gas at the interface of Ba<Subscript>0.8</Subscript>Sr<Subscript>0.2</Subscript>TiO<Subscript>3</Subscript> ferroelectric and LaMnO<Subscript>3</Subscript> antiferomagnet

The temperature dependence of the electrical resistance has been studied for heterostructures formed by antiferromagnetic LaMnO₃ single crystals of different orientations with epitaxial films of ferroelectric Ba_0.8Sr_0.2TiO₃ deposited onto them. The measured electrical resistance is compared to that exhibited by LaMnO₃ single crystals without the films. It is found that, in the samples with the film, for which the axis of polarization in the ferroelectric is directed along the perpendicular to the surface of the single crystal, the electrical resistance decreases significantly with temperature, exhibiting metallic behavior below 160 K. The numerical simulations of the structural and electronic characteristics of the BaTiO₃/LaMnO₃ ferroelectric?antiferromagnet heterostructure has been performed. The transition to the state with two-dimensional electron gas at the interface is demonstrated.     

Detection and manipulation of statistical polarization in small spin ensembles

We report the detection of the square root of N statistical polarization in a small ensemble of electron spin centers in SiO2 by magnetic resonance force microscopy. A novel detection technique was employed that captures the statistical polarization and cycles it between states that are either locked or antilocked to the effective field in the rotating frame. Using field gradients as high as 5 G/nm, we achieved a detection sensitivity equivalent to roughly two electron spins, and observed ultralong spin-lock lifetimes, as long as 20 s. Given a sufficient signal-to-noise ratio, this scheme should be extendable to single electron spin detection.     

Emergence of heterophase structures near phase transitions in photoferroelectric materials

The present study shows that under intense illumination, various spatially nonuniform states may emerge near structural phase transitions in systems with semiconducting properties. Different traveling and stationary autosoliton states are studied, and so is a periodic heterophase structure with alternating para-and ferroelectric phases, which results from a redistribution of electrons on trapping levels. The problem is solved for the one-dimensional case. The emergent behavior is related to the dynamics of the ferroelectric semiconductor as a whole and is an example of synergistic behavior. Zh. éksp. Teor. Fiz. 111, 1465–1476 (April 1997)     

Effect of the deformation of the double bond in chlorinated ethylene on the rate and mechanism of the reaction with ozone

The reactivity of the strained C=C bond of the 1-chloroethylene molecule in the reaction with ozone was studied using ab initio (MP2, CASSCT, MRMP2) and DFT (B3LYP) calculations in conjunction with the 6–31+G** basis set. The mechanisms of concerted and nonconcerted addition were examined. The strain ɛ was introduced into the problem by changing the length of the C=C bond and specifying it as a non-optimized coordinate. It is shown that, at least at ɛ ≤ 2%, the activation energy E _a decreases linearly with increasing strain. The sensitivities of both channels of the reaction to the strain are similar and only slightly dependent on the method of calculation. The results are analyzed within the framework of a previously developed approach, which makes it possible to obtain an analytical dependence of E _a on the force and to relate the change in E _a during deformation to the length and rigidity of the initial and transition states.     

Defects in Nanodiamonds: Application of High-Frequency cw and Pulse EPR,ODMR

Different aspects of applications of electron paramagnetic resonance (EPR) based techniques including high frequency (HF) electron spin echo (ESE), electron-nuclear double resonance (ENDOR) and optically detected magnetic resonance (ODMR) approaches to study diamond nanostructures are examined.