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Resonance Line (resonance + line)
Selected AbstractsESR detection of irradiated broad bean (Vicia faba L.) and kinetics of the radiation induced free radical and Mn2+ signalsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2003Mustafa Polat Summary An ESR (Electron Spin Resonance) investigation on irradiated dry broad bean gave a spectrum which was composed of an equally spaced sextet and a single resonance line. These lines appeared at g = 2.0045 (±0.0005) and originated from Mn2+ ions and radiation induced radicals, respectively. Ground broad bean was used throughout the work to avoid any artefacts arising from a microwave cavity filling factor. Free radical signal intensity was observed to increase exponentially in relation to the increase in absorbed dose over the dose range 1.25,15 kGy. Although the Mn2+ signal increases below room temperature, the signal due to the natural and radiation induced radicals decreases. Above room temperature, they both decreased and these decreases were irreversible. The kinetics of these decreases were studied in detail over a temperature range of 308,373 K by annealing samples at different temperatures for various times. [source] Use of electron spin resonance measurements on irradiated sperma lentil seeds to indicate accidental irradiationINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2003Mustafa Korkmaz Summary The results of electron spin resonance studies on ,-irradiated micro- and macrosperma lentil seeds are reported. Spectra of non-irradiated intact sperma were composed of an equally spaced sextet originating from the presence of Mn2+ ions and a single weak resonance line. Irradiation produced a linear increase in the radical signal intensity in the radiation dose range (0.5,5 kGy) studied, without affecting the Mn2+ signal. Signal intensities of both sperma followed compound exponential decay curves originating from the presence of three different radical species. Heating the sperma cause irreversible decreases in both radical and Mn2+ signal intensities. Two radical species, described in the present work, and a radical of unknown origin were used to explain the experimental results. [source] Spatio-temporal inhomogeneities of laser induced plasma on surface solutionsLASER PHYSICS LETTERS, Issue 11 2004J. Ben Ahmed Abstract A transient plasma created by focusing a nanosecond laser pulse on the surface of ionic solutions of Ca++ and Mg++ is studied spectroscopically. This kind of plasma has a properties which vary significantly with time and over its extended volume. The emissions of ionic and atomic line of calcium and magnesium are analyzed to get information on the electronic temperature, the electronic density and on the kinetics of the population of low atomic and ionic states: 4P1 of CaI, 5S1/2 of CaII, 3P1 of MgII and 3P1/2 of MgII. The temperature is maximal at the plasma center and it drops at the edges. The study of the term as a function of time, where r is the radial position, shows a continue decreasing with time, which implies that the inhomogeneity of the temperature develops with time. On the another side, the electronic density deceases exponentially with time and does not vary significantly with space. These measurements allow us to follow the kinetics of the transformation of calcium (magnesium) from Ca++Mg++ to Ca+(Mg+) to give at the end Ca (Mg) and to understand the behavior of self-absorption phenomena which is observed in the resonance line of CaII at t , 2000 ns to increase with time. The experimental results are simulated by a kinetics model of LTE laser induced plasma in its late relaxation period. (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] 55Mn NMR study in magnetically ordered state of perovskite manganitesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2004K. Shimizu Abstract We present NMR results of Pr1,xSrxMnO3 and their lacunar samples, and also present results of the single crystalline layered manganites La1.2Sr1.8Mn2O7 and La1.2Sr1.6Ca0.2Mn2O7. In Pr1,xSrxMnO3, a single resonance line is observed for 0.27 , x , 0.4, which indicates the sample to be in a metallic state. In the Pr and Sr deficient samples, the NMR line arising from Mn2+ is observed. Introducing deficiency to Pr or Sr sites, a charge disproportionation of the type 2Mn3+, Mn2+ + Mn4+ probably occurs. For La1.2Sr1.8Mn2O7 and La1.2Sr1.6Ca0.2Mn2O7 compounds, the NMR spectra under an external field of 1.5 T are broad and spread with several distinct lines in the frequency range 310,420 MHz. This is different from the results of La1,xSrxMnO3 and Pr1,xSrxMnO3 with a metallic state, where a single line has been observed. The distinct NMR lines are ascribed to Mn4+, Mn3+ and metallic phase, taking account of the results for La1,xSrxMnO3 and Pr1,xSrxMnO3. In addition to the NMR line from the metallic phase, the observation of Mn3+ and Mn4+ lines suggests a phase separation at low temperature in La1.2Sr1.8Mn2O7 and La1.2Sr1.6Ca0.2Mn2O7. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electron paramagnetic resonance line shape investigation of the 29Si hyperfine doublet of the E,, center in a-SiO2PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2007Gianpiero Buscarino Abstract We report an experimental study by electron paramagnetic resonance (EPR) spectroscopy of the E,, center and of its hyperfine structure, consisting in a pair of lines split by 42 mT. Our results show that two types of E,, centers can be distinguished on the basis of the EPR line shapes of their main resonance line and hyperfine structure. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Spectroscopic Diagnostics of Pulsed arc Plasmas for Particle GenerationCONTRIBUTIONS TO PLASMA PHYSICS, Issue 8 2008K. Behringer Abstract Pulsed arc plasmas were diagnosed by means of emission spectroscopy. A capacitor was discharged through argon and hydrogen leading to a few cycles of damped current oscillation with ,120 ,s period and 5-12 kA maximum current. Spectroscopic measurements in the visible range were carried out in order to characterise the electron temperature and density in the arc channel as well as electron and gas temperatures in the afterglow plasmas. Spectra were integrated over 10 ,s time windows and shifted in time from pulse to pulse. The plasmas also contained substantial fractions of electrode material (brass), namely copper and zinc. The electron density was measured in the conventional way from the broadening of H, or from the Ar I Stark width. In the arc channel, it ranged from about 3 · 1022 to 2 · 1023 m,3. The broadening of Zn II lines could also be used. Ratios of Ar I to Ar II and of Zn I to Zn II line intensities were analysed for the electron temperature. Line pairs were found which lay conveniently close in one frame of the spectrometer allowing automatic on-line analysis without relying on reproducibility. Atomic physics models including opacity were developed for Ar II and Zn II in order to check the existence of a Boltzmann distribution of their excited states. These calculations showed that the observed levels were in fact close to thermodynamic equilibrium, in particular, if the resonance lines were optically thick. Electron temperature measurements yielded values between 14000 K and 21000 K. The gas temperature in the afterglow, where particles should have formed, was derived from the rotational and vibrational temperatures of C2 molecular bands. Ratios between Cu I line intensities yielded the electron temperatures. Both were found to be a few 1000 K. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Lactate isotopomer analysis by 1H NMR spectroscopy: Consideration of long-range nuclear spin,spin interactionsMAGNETIC RESONANCE IN MEDICINE, Issue 6 2004Steven G. Lloyd Abstract Lactate is a key metabolite and its rates of cellular uptake and release, its production rates from glucose and glycogen, and its interconversion rate with pyruvate are important determinants of cellular energy production. If lactate precursors such as pyruvate and glucose are labeled appropriately with 13C, 1H NMR spectroscopy provides a means of quantifying lactate production from each source and allows measurement of all these rates within a single experiment. However, due to the multiplicities of the resonance lines (from nuclear spin,spin couplings) in lactate 13C isotopomers, the 1H NMR spectra were found to be more complex than expected, requiring determination of all spin,spin interactions in this anion. All such values were determined for lactate and its precursor pyruvate. The method was then applied to simultaneously measure the rates of exogenous lactate uptake and rates of release of glucose-, glycogen-, and pyruvate-derived lactate in the isolated perfused rat heart. Magn Reson Med 51:1279,1282, 2004. © 2004 Wiley-Liss, Inc. [source] The K, complex of He-like iron with dielectronic satellitesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2001Justin Oelgoetz It is shown that the dielectronic satellites (DES) dominate X-ray spectral formation in the 6.7-keV K, complex of Fe xxv at temperatures below that of maximum abundance in collisional ionization equilibrium Tm. Owing to their extreme temperature sensitivity, the DES are excellent spectral diagnostics for in photoionized, collisional or hybrid plasmas; whereas the forbidden, intercombination and resonance lines of Fe xxv are not. A diagnostic line ratio GD(T) is defined including the DES and the lines, with parameters from new relativistic atomic calculations. The DES absorption resonance strengths may be obtained from differential oscillator strengths, possibly to yield the column densities. The DES contribution to highly ionized Fe should be of interest for models of redward broadening of K, features, ionized accretion discs, accretion flows and K, temporal-temperature variability in AGN. [source] Accurate laboratory wavelengths of some ultraviolet lines of Cr, Zn and Ni relevant to time variations of the fine structure constantMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2000J. C. Pickering The quality of astronomical spectroscopic data now available is so high that interpretation and analysis are often limited by the uncertainties of the laboratory data base. In particular, the limit with which space,time variations in the fine structure constant , can be constrained using quasar spectra depends on the availability of more accurate laboratory rest wavelengths. We recently measured some transitions in magnesium by high-resolution Fourier transform spectroscopy for this purpose, and we now report measurements on some ultraviolet resonance lines of Zn ii (2062 and 2026 Å), Cr ii (2066, 2062 and 2056 Å) and Ni ii (1751, 1741, 1709 and 1703 Å). Apart from the last line, which is very weak, the uncertainty of these measurements is 0.002 cm,1 (0.08 må) for the lines around 2000 Å and 0.004 cm,1 (0.12 må) for the lines around 1700 Å. [source] Pulsed layer growth of AlInGaN nanostructuresPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008Michael Jetter Abstract A pulsed layer growth mode in the metal-organic vapor phase epitaxy (MOVPE) was used to fabricate excellent quality AlInGaN nanostructures. The amount of material was varied, resulting in AlInGaN layer thicknesses between nominally 1.5 nm and 6 nm, respectively. We have analyzed the material properties by X-ray diffraction (XRD) as well as photoluminescence (PL) spectroscopy. The observed XRD-spectra and the PL intensity show the high quality of the deposited material. By analyzing the PL spectra we have found an energetic shift of the resonance lines from 2.65 eV to 3.33 eV with decreasing well thickness. We attribute this shift mainly to the presence of internal electric fields at the AlIn-GaN/GaN interface. Power-dependent and time resolved PL experiments confirm this observation. Comparing the luminescence at elevated temperatures, the pulsed layer epitaxy structures reveal a much higher intensity as the conventional grown samples. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||