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Optical emission in Yb-doped fiber glass materials that can be used for fiber laser applications is studied systematically. The variations of the effective stimulated emission cross-sections and peak emission wavelengths for the transition between F(sub 5/2)(super 2) and F(sub 7/2)(super 2) electronic states in Yb(super 3+) are investigated.

The purpose of the study is to determine the effect of the YAIO3, LaGaO3, and CaYaIO4 crystals codoped with V, Ca, and Ce ions as potential laser media for tunable operation in the visible part of the spectrum. The crystals were studied with the methods of optical spectroscopy and EPR spectroscopy.

The mechanochemical synthesis and magnetic and electric properties of organic polymeric semiconductor that contains paramagnetic and ferromagnetic particles are reported. Polyaniline, polystyrene, Fe[Cl.sub.3] and elemental sulfur are used as starting materials in order to obtain semiconductor polymer composite containing magnetic iron nanoparticles and having flexible thermomechanical properties.

The synthesis of Co, Ni and Fe nanoparticles by the action of elastic wave pulses on solid phase sandwich type samples containing metal salt, reducing agent, polyethylene and polycrylamide is discussed. The stability of metal nanoparticles to oxidation is increased by two orders of magnitude due to the presence of polyacrylamide in reaction composites.

Paramagnetic properties of covalently linked mixed valence chromium complexes in polymers are examined. The quinone ligands in chromium complexes are covalently linked to the structure of the polymers.

Off-axis extra lines have been seen in powder pattern electron paramagnetic resonance (EPR) of Cr(super.3+) in YAlO(sub.3) crystals. They do not belong to the principal X, Y, and Z components of the fine structure. The observed pattern EPR can be used to identify CR(super.3+) as an impurity ion in undoped YAlO(sub.3) crystals.

A new giant magnetoresistance (GMR) material composed of polyailine, polystyrene, sulfur, manganese acetylacetonate, lanthanum, and praseodymium chlorides is described. The external magnetic field has increased conductivity of films and the analysis of transient current kinetics after application of constant voltage to samples have shown the existence of three types of charge carriers ([e.sup.-], [H.sup.+] and [Cl.sup.-].

The issue of traditional seclusion of women as well as the rights of women in Islam in Central Asia is discussed. The traditional seclusion of women is introduced into Islam from the beginning and embodies the role of women as provided by nature itself - that of a home and family maker.

The synthesis and magnetic characterizations of highly crystalline lanthanum strontium manganite (LaSrMn[O.sub.2]) and Eu-doped [Y.sub.2][O.sub.3] and their composites are described. The manganites and their composites with luminescent nanoparticles are very useful for biomedical applications.

Magnetic transitions in manganese benzoquinone coordination polymers and the ab initio calculations of the structure of the binuclear complex are reported. It is shown that the magnetic transitions in the system are because of reversible disproportionation process in the binuclear complex.

The magnetic properties of epitaxial [La.sub.0.7][Ba.sub.0.3]Mn[O.sub.3] and [La.sub.0.7][Sr.sub.0.3]Mn[O.sub.3] films grown by pulsed-laser deposition (PLD) on SrTi[O.sub.3] (STO)/Si (100/111) heterostructures are reported, which have shown remarkable ferromagnetic properties at and above room temperature. The smaller grain size in manganite films on STO/Si might minimize the strain effect through strain relaxation at the interface between SrTi[O.sub.3] and manganites through the formation of three-dimensional islands.

The ferromagnetic resonance (FMR) technique was used to perform a comparative study of colossal magneto resistance (CMR) thin films of different composition and film quality and study the effect of light illumination on the spin system. Results revealed that the width of the FMR signal was closely related to the structural quality of the films and that light illumination below the ferromagnetic phase transition leads to an efficient disorder in the spin system without significant heating of the film.

[La.sub.0.7][Ba.sub.0.3][Mn.sub.3] and [La.sub.0.7][Sr.sub.0.3][Mn.sub.3] films were grown on SrTi[O.sub.3]-buffered Si (100) and Si (111) substituted by pulsed-laser-deposition and magnetically characterized. Observations revealed that all films display sharp magnetic and electrical transitions associated with the colossal magnetoresistance behavior at and above room temperature, thereby illustrating the superior quality of the films.

A coordination polymer containing binuclear manganese complexes with organic catechol/ortho-quinone ligands is mechanically synthesized and characterized. Electron paramagnetic resonance and infrared spectroscopic data measurements reveal that the binuclear manganese complex is covalently linked to the chain of polystyrene, while theoretical electron-spin-resonance spectrum analysis showed a triplet state of the complex with two nonequivalent manganese ions couples to each other by spin exchange.

ZnMnO films grown by the pulsed-laser deposition technique were annealed in different temperatures and their ferromagnetic resonance was studied. The findings reveal that oxygen plays a vital role for controlling the ferromagnetic properties in ZnMnO films.

Magnetic properties of ZnMnO and Co:Ti[O.sub.2] films fabricated by pulsed laser deposition by varying annealing conditions are explored. Results indicate that the mechanism for ferromagnetism lies, probably, within the perspective of charge transfer between Mn ions through oxygen.

Paramagnetic properties of binuclear niobium complexes Nb-O-Nb with two nonequivalent Nb(super 4 +) ions in lithium-niobium phosphate glasses are investigated. Experimental electron paramagnetic resonance spectrum analysis revealed nonequivalent distribution of the charge and electron spin density between two Nb atoms.

A sharp microwave response centered at zero magnetic field was observed in manganese- and iron-doped Na[sub 2]O-CaO-MgO-SiO[sub 2] glasses with phase opposite to the normal Mn[sup +2] and Fe[sup +3] paramagnetic signals. The response can be described as magneto-induced microwave conductivity in the dielectric glass that derives from spin-dependent charge migration within the first coordination sphere of the paramagnetic ion. In contrast to the spin-polarized tunneling in ferromagnets between different valence states of metals, the observed effect is due to spin-dependent tunneling that occurs in the vicinity of manganese or iron in diluted paramagnetic systems. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]