Home About us Contact
|
Home About us Contact | ||
|
|
||
ESR Signal (esr + signal)
Selected AbstractsDetection of diluted marine tertiary tephra by electron spin resonance and magnetic measurementsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2003B. Ananou SUMMARY Oligocene sediments from ODP leg 115 (South Indian Ocean), Site 709 and Site 711, have been investigated using electron spin resonance (ESR) and magnetic susceptibility measurements, to detect volcanic tephra layers of supposed Ethiopian traps origin. The results obtained at room temperature, without separating the volcanic material from the bulk sediment, show that the ash-content strongly influences the lineshape and intensity of the ESR signal. As a result, the ESR alone, can be used as a powerful tool for characterizing the diluted ash-content of marine sediments. We have also found a strong similarity between the ESR spectra of the same tephra layers from the two sites. [source] Accuracy of the Calibration Curve Method for Absorbed Dose Assessment in Irradiated Refrigerated Chicken BoneJOURNAL OF FOOD SCIENCE, Issue 1 2001A.A. Basfar ABSTRACT: The influence of the decay of the radiation induced free radicals on electron spin resonance (ESR) bone dosimetry was studied. The absorbed doses in irradiated bone are usually assessed by applying correction factors for decay. An alternative procedure is presented in which the ESR readout was performed only when the ESR signal had reached good stability for the bone samples used to establish the calibration curves and also on bones for which absorbed dose assessment was to be made. The results of the evaluated doses obtained by using this approach were the same as the ones obtained by using corrections for the decay of ESR signals. [source] The oxygen vacancy in Ga2O3: a double resonance investigation,MAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2005H. J. Kümmerer Abstract When produced under reducing conditions, ,-Ga2O3 is transformed into an n -type semiconductor with delocalized conduction electrons that exhibit a very strong electron spin resonance (ESR) and a strong hyperfine coupling to the gallium nuclei of the host lattice. We apply the Overhauser-shift technique to investigate single crystals of this compound. With extension to the high magnetic field of a W-band spectrometer, we were able to resolve all spectral lines that were recorded and to assign them to their corresponding electronic and nuclear states. This separate analysis was the basis to access additional sample characteristics: the hyperfine coupling that is actually averaged out in the ESR signal, as well as the nuclear relaxation rates could be analyzed. Systematic measurements by varying the microwave power revealed the Overhauser shift in thermal equilibrium. The signal could be tracked to very small microwave saturation parameters, at which the deviation from the usual linear relation between power and shift becomes evident and the shift clearly approaches a constant value. This value in equilibrium was determined directly from a fit to a sequence of measurements, whereas standard X-band experiments only provided indirect conclusions. The probability densities of the electrons at the nuclei in the two nonequivalent crystallographic positions,the lattice sites with octahedral and tetrahedral coordination,could also be determined directly. The enhanced resolution revealed an otherwise hidden substructure in the nuclear resonance signals. On the basis of a microscopic model, this structure could be used to probe the environment of the oxygen vacancy more precisely and to determine the extension of the electronic wave function of the donor electrons. Copyright © 2005 John Wiley & Sons, Ltd. [source] TL, ESR and reflectance in natural diopside crystalPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2007N. F. Cano Abstract In this paper, results on thermoluminescence (TL) as well as electron spin resonance (ESR) and reflectance of Brazilian diopside samples are presented. The behaviour of the TL centres, ESR signal and reflectance bands under irradiation and heat treatments are examined. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Scavenger activity of Allium psekemense B. FedtschPHYTOTHERAPY RESEARCH, Issue 5 2002tajner Abstract In the present study the antioxidative properties of the bulbs, leaves and stalks of Allium psekemense B. Fedtsch were investigated. The activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, glutathione peroxidase), quantities of malonyldialdehyde, superoxide and hydroxyl radicals and reduced glutathione and also the content of total flavonoids, chlorophylls a and b, carotenoids, vitamin C and soluble proteins were determined. The results indicate that extracts from all plant organs exhibited antioxidant activity. The highest antioxidant activity was observed in the leaves. Furthermore, the ESR signal of DMPO-OH radical adducts in the presence of the leaf phosphate buffer (pH 7) extract was reduced by 54.3%. Copyright © 2002 John Wiley & Sons, Ltd. [source] Accuracy of the Calibration Curve Method for Absorbed Dose Assessment in Irradiated Refrigerated Chicken BoneJOURNAL OF FOOD SCIENCE, Issue 1 2001A.A. Basfar ABSTRACT: The influence of the decay of the radiation induced free radicals on electron spin resonance (ESR) bone dosimetry was studied. The absorbed doses in irradiated bone are usually assessed by applying correction factors for decay. An alternative procedure is presented in which the ESR readout was performed only when the ESR signal had reached good stability for the bone samples used to establish the calibration curves and also on bones for which absorbed dose assessment was to be made. The results of the evaluated doses obtained by using this approach were the same as the ones obtained by using corrections for the decay of ESR signals. [source] Origin of electron spin resonance in La0.7Ca0.3MnO3PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003Keon Woo Joh Abstract An electron spin resonance study was carried out for a La0.7Ca0.3MnO3 bulk sample above the ferromagnetic ordering temperature. From careful analysis on the ESR parameters, it is shown that itinerant spins interacting with magnetic spin clusters in bottleneck regime are responsible for the ESR signals. [source] Highly Dispersed Ruthenium Hydroxide Supported on Titanium Oxide Effective for Liquid-Phase Hydrogen-Transfer ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2008Kazuya Yamaguchi Dr. Abstract Supported ruthenium hydroxide catalysts (Ru(OH)x/support) were prepared with three different TiO2 supports (anatase TiO2 (TiO2(A), BET surface area: 316,m2,g,1), anatase TiO2 (TiO2(B), 73,m2,g,1), and rutile TiO2 (TiO2(C), 3.2,m2,g,1)), as well as an Al2O3 support (160,m2,g,1). Characterizations with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and X-ray absorption fine structure (XAFS) showed the presence of monomeric ruthenium(III) hydroxide and polymeric ruthenium(III) hydroxide species. Judging from the coordination numbers of the nearest-neighbor Ru atoms and the intensities of the ESR signals, the amount of monomeric hydroxide species increased in the order of Ru(OH)x
| | ||||||||||||