Efficient electro-optic semiconductor medium based on type-II heterostructures

An electro-optic medium based on the type-II semiconductor superlattice is proposed. Electrooptic modulation of the intensity of optical reflectance of the electro-optic medium integrated into a vertical Fabry-Perot cavity is studied by the optical-reflectance-spectroscopy method. The experimental data are approximated using an oscillator model of exciton absorption. The efficiency of the electro-optic medium in the case of detuning from the absorption peak by 50 meV in electric fields of 0–50 kV/cm is 10^?9 m/V at a medium filling factor of 100%.     

Iron(III) Removal from Aluminum Sulfate Solutions by Sorption

Russian Journal of Applied Chemistry - Sorption of aluminum(III) and iron(III) from their individual solutions and of iron(III) impurity from Al2(SO4)3 solutions on macroporous resins, Puromet...     

Femtosecond Dynamics of Optically Induced Anisotropy of Complex Molecules in the Gas Phase

The evolution of optically induced anisotropy in an equilibrium ensemble of free asymmetric tops under collisionless conditions has been investigated theoretically and experimentally. The dynamics of the orientation correlation functions has been studied, the results of femtosecond experiments on measurement of relaxation of the optically induced anisotropy for perylene in the gas phase are presented, and their interpretation within the framework of the theory developed is given. It is shown that in contrast to stationary anisotropy, its time kinetics has more complete characteristic information about the dynamics of vector correlations in a molecular ensemble.     

Alkylsulfonyl Halides as Initiators of Cationic Polymerization of Oxazolines

The example of methanesulfonyl halides has shown the possibility of initiating cationic polymerization of 2-oxazolines by alkylsulfonic acid halides. Chain propagation rate constants and activation energy of the processes have been determined. The kinetic mechanisms suggest a slow initiation of polymerization followed by fast chain propagation. It has been shown that the polymerization of 2-ethyl-2-oxazoline initiated by aliphatic sulfonyl halides proceeds predominantly at the active centers of the ionic type. The synthesis of oligo(3-sulfonyl)methacrylate-graft-poly(2-isopropyl-2-oxazoline) is described as an example of using alkylsulfonyl halides for graft copolymers.     

Emission-Line Width and α-Factor of 850-nm Single-Mode Vertical-Cavity Surface-Emitting Lasers Based on InGaAs/AlGaAs Quantum Wells

The emission-line width for 850-nm single-mode vertical-cavity surface-emitting lasers based on InGaAs/AlGaAs quantum wells is studied. The width of the emission line for a laser with a 2-μm oxide current aperture attains it minimum (~110 MHz) at an output power of 0.8 mW. As the optical output power is further increased, anomalous broadening of the emission line is observed; this is apparently caused by an increase in the α-factor as a result of a decrease in the differential gain in the active region under conditions of increased concentration of charge carriers and of high internal optical losses in the microcavity. The α-factor is estimated using two independent methods.     

Composite Ion Exchangers Based on KU-23 and KM-2P Cation Exchangers and Nickel(III) Hydroxide and Their Use for Purification of Nickel Sulfate Solutions To Remove Cobalt(II) Impurity

A method of preparing composite ion exchangers based on macroporous cation exchangers and nickel(III) hydroxide was developed, and their suitability for deep purification of nickel(II) sulfate solutions to remove small amounts of cobalt(II) was demonstrated.     

Chromatographic Techniques in Forensic Chemical Examinations

Some aspects of the use of chromatographic analytical techniques in the forensic chemical examination of materials, substances, and products were considered. The detection and subsequent expert examination of various materials (psychoactive drugs, explosives, gunshot residues, etc.) was exemplified. It was demonstrated that the effectiveness and validity of the evidential matter of expert examinations can be provided by tdeveloping a uniform system for comprehensive forensic chemical examinations of material and products; within the framework of this system, expert examinations should be performed with a required reliability and accuracy.     

Complexes of cuprous phenylacetylenide with phosphorous acid amides

Complexes of cuprous phenylacetylenide (CPA) were obtained with various amides of phosphorous acid, which are cubane-like tetramers (PhC=CCuL)₄. Copper is coordinated at the phosphorus atom in these complexes. The coordination shift of the ligands in the³¹P NMR spectra are directly dependent on the electronegativity of the heteroatoms at phosphorus.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 176–182, January, 1990.The authors are grateful to I. A. Garbuzova for taking the Raman spectra.