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We describe a zero loop-area Sagnac interferometer at oblique incidence for detecting magneto-opticKerr effect arising from in-plane magnetization in a sample. By exploiting properties of polarization states under relevant crystal symmetry transformation, we show that contributions from longitudinal and transverse Kerr effects can be separated. In addition we can select one optical arrangement out of four that detects the longitudinal effect with the highest signal-to-noise ratio. Compared to finite loop-area Sagnac interferometers operating at oblique incidence, the zero loop-area interferometer involves significantly fewer optical elements and is thus more stable against drifts in the optical system. For demonstration, we measured the in-plane magneto-optic Kerr effect from a 42-nm Ni film. [ABSTRACT FROM AUTHOR]

Qualitative transformations of spectra of Electron Paramagnetic Resonance, EPR, were found in KH2PO4 crystals grown from liquor with 10-5-10-1 wt. % of anatase TiO2 nanoparticles in comparison with nominally pure KH2PO4. The nanoparticles have larger segregation coefficient for prismatic parts of the crystals than for pyramidal ones. Significant decrease in resonance absorption, complete disappearance of EPR lines of Fe3+ and Cr3+ centers, and appearance of four weak lines of equal intensities together with broad asymmetric lines with g-factors about 2.07-2.5 was observed in pyramidal parts grown with concentration of TiO2 nanoparticles larger than the threshold value 10-2wt. %. The four lines were attributed to non-controlled impurity As substituted for P. In the presence of TiO2 nanoparticles, non-paramagnetic AsO43- clusters trap electrons becoming AsO44-. Disappearance of Fe3+ and Cr3+ centers was explained by their recharge to "EPR-silent" states and/or pairing at the surface of TiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

Results from the successful growth of high quality KH2PO4 (KDP) crystals with incorporated TiO2 anatase nanoparticles and the characterization of these crystals using several complementary methods are presented. The study allowed the nature and distribution of macroscopic and microscopic defects in the KDP:TiO2 crystals to be clarified. The relationship between these defects and the distribution of TiO2 nanoparticles, and the influence of incorporated nanoparticles on the nonlinear optical properties of composite crystals in comparison with pure crystals were also elucidated. Visual observations, transmission and scanning electron microscopy have shown that the anatase nanoparticles were captured mainly by the pyramidal growth sector and, to a considerably lesser extent, by the prismatic growth sector. Energy dispersive x-ray analysis was able to confirm that the growth layer stacks contain the TiO2 particles. Fourier transformation infrared spectra have clearly shown the presence of an absorption band at about 800 cm-1 in both KDP:TiO2 and TiO2, and the disappearance of the band, associated with hydroxyl OH- groups on the TiO2 surface in KDP:TiO2. Significant variation in the imaginary and real parts of the cubic nonlinear optical susceptibilities and refractive index changes at continuous wave excitation were found in prism and pyramid parts of pure KDP and KDP:TiO2 samples. Deciphering complicated electron paramagnetic resonance spectra in KDP:TiO2 and comparison with published data permitted the identification of paramagnetic defects along with their associated g-factors and zero-field splitting parameters (in some cases for the first time). It was found that the dominant lines belong to four different centers FeA3+, FeB3+, CrR3+, and CrGB3+. From analysis of line intensities it was concluded that the concentration of intrinsic defects like potassium and hydrogen vacancies in KDP:TiO2 is comparatively small, that the concentration of non-controlled impurities in nominally pure KDP samples is several times larger than in KDP:TiO2, and that the concentration of non-controlled impurities in the prismatic part of the KDP:TiO2 boule is approximately twice as large as in the pyramid part. [ABSTRACT FROM AUTHOR]

Two bis(1-pyrazolyl)alkane ligands, bis(3,5-dimethyl-1-pyrazolyl)methane and bis(4-iodo-3,5-dimethyl-1-pyrazolyl)methane, and their copper(II) complexes, bis(3,5-dimethyl-1-pyrazolyl)methanedinitratocopper(II) [CuL1(NO3)2] and bis(4-iodo-3,5-dimethyl-1-pyrazolyl)methanedinitratocopper(II) [CuL2(NO3)2]·2H2O, were prepared. Physiochemical properties of the copper(II) complexes were studied by spectroscopic (UV–vis, IR, EPR) techniques and cyclic voltammetry. Spectroscopic analysis revealed a 1:1 stoichiometry of ligand:copper(II) ion and a bindentate coordination mode for the nitrate ions in both of the complexes. According to experimental and theoretical ab initio data, the copper(II) ion is located in an octahedral hexacoordinated environment. Both complexes were able to catalyze the dismutation of superoxide anion ( $$ {\text{O}}^{{\bullet - }}_{{\text{2}}} $$ ) (pH 7.5) and decomposition of H2O2 (pH 7.5) and peroxynitrite (pH 10.9). In addition, both complexes exhibited superoxide dismutase (SOD) like activity toward extracellular and intracellular reactive oxygen species produced by activated human neutrophils in whole blood. Thus, these complexes represent useful SOD mimetics with a broad range of antioxidant activity toward a variety of reactive oxidants. [ABSTRACT FROM AUTHOR]