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1.
With electron spin resonance (ESR) spectroscopy, we revealed various free radicals in commercially available pepper in Japan
before and after γ-irradiation. The representative ESR spectrum of the pepper is composed of a sextet centered atg=2.0, a singlet at the sameg-value and a singlet atg=4.0. The first signal is attributable to a signal with hyperfine interactions of the Mn2+ ion (hyperfine constant, 7.4 mT). The second signal is due to an organic free radical apparently induced by a sterilization
process. The third signal may originate from the Fe3+ ion in the nonheme proteins. The progressive saturation behavior at various microwave power levels indicated quite different
relaxation behaviors of those radicals. Namely, the peak intensity of the organic free radical component decreases in a monotonic
fashion, whereas the Mn2+ and Fe3+ ESR signals substantially remain constant. This evidences the presence of three independent radicals in the pepper before
irradiation. Upon γ-irradiation, a new pair of signals appeared in the pepper. The progressive saturation behavior of the
pair peaks after the irradiation showed a quite different behavior as compared with the free radical centered atg=2.0. For the measure of irradiation effects, we propose a universal index for the ESR analysis of irradiated dry foods. 相似文献
2.
The electron spin resonance (ESR) spectra for each beige and brown sepiolites from Polatli-Ankara, Turkey, a clay mineral of Mg8Si12O30(OH)4(OH2)4(H2O)8, at 77 K have their own single characteristic peak atg ≈ 1.99, which begins to anneal from 437 and 536°C, respectively. The sextet lines of Mn2+ were also observed in addition to two peaks (g = 4.4 and 5.0) associated with Fe3+. A high-quality sepiolite called “meerschaum” from Sepetci-Eskisehir, Turkey, has two characteristic peaks atg ≈ 1.99, which begins to anneal from 419°C, and atg ≈ 2.03. ESR intensities of the signal atg ≈ 1.99 for beige, brown sepiolites and meerschaum are enhanced by γ-ray irradiation to give equivalent dosesD E = 11.8 ± 3.4, 4.7 ± 2.3 and 4.6 ± 1.2 kGy, respectively. The ESR ages obtained by assessing the annual dose rate from the content of238U,232Th and40K determined by γ-ray spectroscopy are 1.8 ± 0.8, 0.7 ± 0.5 and 0.9 ± 0.2 Ma, respectively, falling into the Pliocene Epoch in geological time scale in agreement with the stratigraphy. 相似文献
3.
Electron spin resonance (ESR) study was done on calcite encrustation on Fili neotectonic fault surface, Greece. Normally such
calcite encrustations on fault surfaces are not observed. Significantly, the ESR study has detected the presence of nitrate
NO32− radical in this calcite encrustation, havingg
⊥=2.0063±0.0001 and hyperfine coupling constantA
⊥=3.44 mT, the second such detection of nitrate NO32− radical following a sample from Scott Glacier, Antarctica. From isochronal thermal annealing measurement the NO32− radical was found to be quite stable, only fully annealed at 475°C. This study also shows that the ESR, as a tool, can be
suitably applied to date the age of formation of the calcite encrustation with SO3− as an ESR dating signal by additive γ-ray irradiation. A preliminary estimation indicates the age of formation of calcite
precipitation at Fili fault, Greece to be about 5600 years. 相似文献
4.
Lithium trifluoromethane-sulfonate (Li-TFMS:CF3SO3Li) irradiated by γ-rays showed an electron spin resonance (ESR) powder spectrum having the rhombicg-factor ofg xx = 2.0259 ± 0.0005,g yy = 2.0112 ± 0.0005 andg zz = 2.0025 ± 0.0005 and a triplet hyperfine coupling constant ofA xx/gβ= 0.8 ± 0.15 mT.A yy andA zz are not obtained because of the broadened spectrum. The energy levels,g-factor,A xx/gβ and optical absorption spectrum of several conceivable radicals such as C⋅F2SO3Li, CF3-S-O⋅ and CF3-S-O-O⋅ have been calculated by softwares MOPAC-V2 and Gaussian-98 based on ROHF (Restricted Hatree-Fock for open shell molecule). The most probable radical was ascribed to CF3-SO⋅ from both calculated and experimental results. The response to γ-ray dose and the thermal stability have been studied in addition to the effect of UV illumination for possible use of the signal intensity in ESR dosimetry. The obtained number of free radicals per 100 eV (G-value) was 1.23 ± 0.40. 相似文献
5.
C. Corredor J. Diaz J. M. Diaz H. A. Farach C. P. Poole 《Applied magnetic resonance》1995,9(3):309-317
The electron spin resonance spectra fromGallus domesticus egg shells exhibit a strong free radical singlet, a spectrum due to Mn2+ ions in a calcite site, a low field line line atg≈30/7 due to Mn2+ in a rhombic site, and spectral lines arising from Fe3+ ions. Details of the ESR spectral lines did not correlate with fertile, non-fertile or color type egg-shell characteristics. 相似文献
6.
Baran N. P. Vorona I. P. Ishchenko S. S. Nosenko V. V. Zatovskii I. V. Gorodilova N. A. Povarchuk V. Yu. 《Physics of the Solid State》2011,53(9):1891-1894
The EPR studies of synthetic hydroxyapatite containing carbonate and nitrate ions exposed to γ-ray and UV irradiations have
been performed. It has been found that γ irradiation leads to the formation of both NO32− and CO2− paramagnetic centers, while the UV irradiation induces only NO32− centers. To explain this fact, the hypothesis has been proposed, according to which in the hydroxyapatites studied, there
coexist complexes consisting of nitrate ions and shallow electron traps that serve as sources of secondary electrons during
UV irradiation. The EPR spectroscopy parameters (g and A) of the detected centers have been determined and compared with similar centers in hydroxyapatite with a different impurity
composition. The study of the thermal stability of the centers has demonstrated that, in the temperature range 20–300°C, the
NO32− centers formed by UV irradiation are more stable than the same centers created by γ-ray irradiation. 相似文献
7.
Zheng Yong Zhou Xiaohong Zhang Yuhu Guo Yingxiang Lei Xiangguo Liu Zhong Liu Minliang Luo Wanju Wen Shuxian Zhu Lihua Yang Chunxiang 《中国科学G辑(英文版)》2003,46(2):131-136
The high-spin states of157Yb have been studied via the reaction of144Sm(16O, 3n) at16O energy of 90 MeV using techniques of in-beam γ-ray spectroscopy. Measurement of γ-γ-t coincidences was performed with 11 BGO(AC)HPGe detectors. Based on the γ-γ coincidence relationships and the measured results
of γ-ray anisotropies and DCO ratios, the level scheme for157Yb was established. The shape co-existence and structural evolution of thevi13/2 band with increasing angular momentum in157Yb have been discussed. The systematics of thevi13/2 bands in theN=87 odd-A isotones have been compared. 相似文献
8.
G. V. Valsky A. M. Gagarski I. S. Guseva D. O. Krinitsin G. A. Petrov Yu. S. Pleva V. E. Sokolov V. I. Petrova T. A. Zavarukhina T. E. Kuzmina 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(6):767-771
The angular dependence of the γ-ray asymmetry relative to the plane formed by the directions of fission-fragment separation
and longitudinal polarization of the thermal neutrons inducing 235U(n, f) fission was investigated. The results obtained confirm the existence of γ-ray emission asymmetry and the dependence of its
coefficient on the angle between the axes of the fission-fragment and γ-ray detectors, revealed for the first time by the
ITEP group at the FRM-II reactor in Munich. The observed T-odd effect of around ∼2 × 10−4 can be explained by the angular anisotropy of the γ-ray emission from fission fragments with large angular momenta oriented
relative to the fission axis. 相似文献
9.
V. A. Zheltonozhskii A. N. Savrasov 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(6):829-832
Isomeric yield ratios of 115m,g
Cd and 120m,g
Sb were measured in the (γ, n) reaction in the near-threshold region at γ-ray energies of 9.6, 9.8, 10.0, and 10.5 MeV. Experimental
values of the isomeric yield ratios were compared with theoretical values calculated using the TALYS-1.0 program package.
The (γ, n) reaction is shown to have a statistical character in the excitation region of residual nuclei 0.3–1.5 MeV. 相似文献
10.
We review high-energy scattering processes that are sensitive to the hadronic structure of the photon, describing theoretical
predictions as well as recent experimental results. These processes include deep-inelastic electron-photon scattering ate
+
e
− colliders; and the production of jets, heavy quarks and isolated photons in the collision of real photons ate
+
e
− colliders, as well as in photon-photon collisions atep colliders. We also comment on minijet based calculations of totalγp andγγ cross-sections, and discuss the possibility that future lineare
+
e
− colliders might produce very large photon fluxes due to the beamstrahlung phenomenon; in the most extreme cases, we predict
more than one hadronicγγ event to occur at every bunch crossing. 相似文献
11.
Hiromi Kameya Hideo Nakamura Mitsuko Ukai Yuhei Shimoyama 《Applied magnetic resonance》2011,40(3):395-404
Using electron spin resonance (ESR) spectroscopy, we revealed the irradiation-induced radicals in cellulose and starch. Before
gamma-ray irradiation, no ESR signals were observed in both the glucose polymers. However, after gamma-ray irradiation, a
singlet at g = 2.0 was observed, and a pair of side signals appeared simultaneously. The side signals were found at the symmetric field
positions at both sides of the singlet signal. The side signals were visible in cellulose but not in starch. The side signals
are found to be a precise indicator for irradiation effects in cellulose. They are originated from neither the peroxide radical
of glucose polymer nor the so-called cellulosic radicals. By the simulation method, we found that the side signals are originated
from a triplet due to a hyperfine interaction with two protons. By the theoretical simulation, we revealed that the signal
undergo the rotational motions rather than rigid limit state (or no motion). 相似文献
12.
The magnetic hyperfine interaction of Cu in Fe, Co and Ni was studied by means of the γ-γ perturbed angular correlation method
using62Zn(62Cu) as a probe. With the publishedg-factor (g=+0.661(12)) of the 41 keV, 2+ state hyperfine fields ofB
HF=16.95(51) T,B
HF=13.15(41) T andB
HF=4.05(30) T atT=0 K for Cu in Fe, Co and Ni are derived, respectively. The systematic discrepancy of these values with several independent
measurements of these hyperfine fields is removed by deriving a new value ofg=0.55(5) for the 41 keV, 2+ state of62Cu. 相似文献
13.
YOSHIO SAKAGUCHI 《Molecular physics》2013,111(8):1129-1135
The photochemical reaction of 2-methyl-1,4-naphthoquinone in sodium dodecyl-sulphate micellar solution was investigated with an optical detection ESR apparatus working at 17.44 GHz (Ku-band). The Ku-band RYDMR spectra are obtained from the transient optical absorption and the stationary absorption of the reaction product, and the shift of the spectral peak compared with the spectra at 331 mT is reproduced well by the difference in g of the component radicals. The microwave pulse length dependence shows the quantum beat originated from the conversion between triplet ±1 states and the mixed state of singlet and triplet 0 states by the microwave field. The decay rate of the radical pair in triplet ±1 at 622 mT was determined to be 7.1 ± 1.1 × 105 s?1 by changing the irradiation time of a short (20 ns) microwave pulse with reference to the laser excitation. This value is smaller than that at 331 mT, as expected by the relaxation mechanism. 相似文献
14.
X.H. Zhou Y. Zheng Y.H. Zhang Z. Liu Q.Y. Pan Z.G. Gan T. Hayakawa M. Oshima T. Toh T. Shizuma J. Katakura Y. Hatsukawa M. Matsuda H. Kusakari M. Sugawara K. Furuno T. Komatsubara 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):253-255
The high-spin states of 145Tb have been studied in the 118Sn(32S, 1p4n) reaction at 32S energies from 161 to 175 MeV using techniques of in-beam γ-ray spectroscopy. Measurements of γ-ray excitation functions
and γ-γ-t coincidences were performed with 12 BGO(AC)HPGe detectors. Based on the measured results of γ-γ coincidences, γ-ray anisotropies
and DCO ratios, a level scheme for 145Tb was established for the first time. The observed excited states show typical irregular pattern in a spherical nucleus,
and the low-lying levels have been interpreted qualitatively with a particle-core coupling.
Received: 21 September 2001 / Accepted: 9 November 2001 相似文献
15.
S. V. Demishev A. V. Semeno N. E. Sluchanko N. A. Samarin J. Singleton A. Ardavan S. J. Blundell W. Hayes S. Kunii 《JETP Letters》1996,64(10):760-766
In undoped pure single crystals of the mixed valence compound SmB6 anomalous ESR absorption is observed in the frequency range v=40–120 GHz at temperatures of 1.8–4.2 K. The ESR for the case of the coherent ground state consists of two components corresponding
to g-factors g
1=1.907±0.003 and g
2=1.890±0.003. The amplitude of both ESR lines strongly depends on temperature in the temperature range studied: the amplitude
of the first line with g=g
1 increases and the amplitude of the second line decreases with temperature. A model based on consideration of intrinsic defects
in the SmB6 crystalline lattice, with a densit ∼1015−1016 cm−3, is suggested as an explanation for the anomalous ESR-behavior. In the frequency range v>70 GHz at T=4.2 K, in addition to the main ESR lines, a new magnetic resonance with a hysteretic field dependence is discovered.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 10, 707–712 (25 November 1996)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
16.
D.C. Biswas B.K. Nayak M. Cinausero B. Fornal G. Viesti D. Bazzacco M. DePoli D. Fabris E. Fioretto M. Lunardon D.R. Napoli G. Nebbia G. Prete C.A. Ur G. Vedovato 《The European Physical Journal A - Hadrons and Nuclei》1999,4(4):343-348
The high energy γ-ray emission accompanying the spontaneous fission of 252Cf has been measured in coincidence with individual fission fragments selected by discrete γ-ray transitions. The enhancement
of the γ-ray emission probability in the energy range Eγ= 3–8 MeV has been observed for the fission fragments in the region of nearly symmetric mass splitting, confirming results
reported in previous investigations. The γ-γ coincidence technique employed in the present work clearly demonstrate that the
major contribution to this enhancement is caused by the fission channels where one fragment is near to the N= 82 or Z= 50 shell closures. The high energy γ-ray emission probability does not show any significant dependence on the number of
neutrons emitted in the fission process, supporting the hypothesis that high energy γ-rays are mainly emitted from the fragments
after the neutron evaporation.
Received: 22 December 1998 相似文献
17.
Shen Shuifa Fang Keming Gu Jiahui Liu Qingcheng Xu Furong 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):149-158
The decay of 95Ru has been investigated by means of γ-ray spectroscopy. The 95Ru nuclei were produced by the reaction 92Mo( α, n) 95Ru at a beam energy of 17MeV. High-purity Ge detectors have been used singly and in coincidence to study γ-rays in the decay of 95Ru to 95Tc. 132 γ-rays are reported, among them, energies and intensities for 127 transitions have been determined. A decay scheme of 95Ru with 31 levels is proposed which accommodates 127 of these transitions. Spins and parities for three new levels are proposed
from calculated log ft values, measured γ-ray branching ratios, and in-beam experiment results of the daughter nucleus 95Tc. Combining with the high-spin states observed by in-beam γ-ray spectroscopy of previous decay works, the structure of the excited states of 95Tc is discussed in the framework of the projected shell model. 相似文献
18.
The intensive unresolved central line associated with organic free radicals in electron paramagnetic resonance (EPR) spectra
of petroleum is interpreted as resulting from the superposition of signals from different radical species with very close
g values. The mobility of a free radical in crude oil is relatively low due to the high oil viscosity. Aimed at characterizing
free radicals in the oil byproduct, the present study is concerned with the investigation of marine diesel (bunker), a low-viscosity
oil. Marine diesel was studied by EPR spectroscopy at X-band (9 GHz) in the temperature range from 170 to 400 K. Despite the
viscosity at room temperature (2.5·10−3 kg/m·s) and the tumbling correlation time for free radicals of about 10−7 s suggesting a high mobility of free radicals in marine diesel, the EPR spectra at room temperature did not exhibit resolved
lines, but only an envelope with a poor signal-to-noise ratio. The same behavior was observed from 170 to 373 K. Above 373
K, the EPR spectrum exhibited resolved lines: a superposition of a septet-quartet, a sextet-quartet and a quintet-quartet
group of lines was identified with the following parameters: g = 2.003 ± 0.001, proton hyperfine couplings A = 6.41 ± 0.03 G (septet) and A′ = 1.82 ± 0.02 G (quartet); g = 2.003 ± 0.001, A = 6.21 ± 0.03 G (sextet) and A′ = 1.64 ± 0.02 G (quartet); g = 2.003 ± 0.001, A = 6.16 ± 0.03 G (quintet) and A′ = 1.83 ± 0.02 G (quartet), which were attributed to phenalenyl radicals and their derivatives. Below 373 K, phenalenyl dimerization
prevented its detection by EPR. 相似文献
19.
Y. Zheng X.H. Zhou Y.H. Zhang Y.X. Guo X.G. Lei Z. Liu J.J. He M.L. Liu W.J. Luo S.X. Wen L.H. Zhu C.X. Yang 《The European Physical Journal A - Hadrons and Nuclei》2002,14(2):133-136
The high-spin states of 157Yb have been studied via the 144Sm(16O, 3n) reaction at 16O energy of 90 MeV using techniques of in-beam γ-ray spectroscopy. Measurement of γ-γ-t coincidences was performed with 11 BGO(AC)HPGe detectors. Based on the measured results of γ-γ coincidences, γ-ray anisotropies
and DCO ratios, the level scheme for 157Yb was established. The shape co-existence and structural evolution of the νi
13/2 band with increasing angular momentum in 157Yb have been discussed. The systematics of the νi
13/2 bands in the N = 87 odd-A isotones have been compared.
Received: 7 January 2002 / Accepted: 10 April 2002 相似文献
20.
J. Rikovska 《Hyperfine Interactions》1985,26(1-4):963-994
The present status of γ-ray linear polarization measurements on oriented nuclei is discussed. The formalism used in the analysis
of experimental data is summarized and complemented by formulae for γ-transitions with triple multipole mixing. A survey of
the present technique of detection of γ-ray linear polarization, using Compton polarimeters, is given. Two important applications
of γ-ray linear polarization measurements are briefly surveyed, namely, the measurement of theg-factors excited states and the investigation of time-reversal symmetry in atomic nuclei. 相似文献