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1.
Since its observation in 1985 nuclear resonant scattering of synchrotron radiation has become an excellent tool to study hyperfine
interactions in solids. It combines the advantages of both local probe experiments and scattering techniques and gives valuable
information on magnetic and electronic structures in case of NFS experiments. Experiments benefit from the outstanding beam
quality of 3rd generation synchrotron radiation sources, as the small beam size and divergence.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
T. Achtzehn J. Lassen P. Bricault D. Albers T. E. Cocolios M. Dombsky V. Hanemaayer J. P. Lavoie N. Lecesne M. R. Pearson E. J. Prime K. D. A. Wendt 《Hyperfine Interactions》2007,174(1-3):27-32
Many experiments carried out at radioactive beam facilities require the production of intense, isotopically clean and isobar
free beams of a particular isotope. At TRIUMF the addition of a resonant ionization laser ion source (TRILIS) enables a multitude
of new beams and therefore new experiments to be carried out. 26Al was one of the first radioactive ion beams delivered to an experiment using TRILIS. This paper outlines the development
of the 26Al ion beam for nuclear astrophysics.
相似文献
3.
F. H. M. Cavalcante A. W. Carbonari R. N. Saxena J. Mestnik-Filho 《Hyperfine Interactions》2004,158(1-4):125-129
Perturbed gamma–gamma angular correlation technique was used to measure the magnetic hyperfine field at Gd sites in the intermetallic
compound GdAg using the 140La→140Ce nuclear probe. A major and well-defined magnetic interaction is observed at 140Ce substituting Gd sites in GdAg below 130 K, corresponding to a ferromagnetic ordering of Gd moments. The temperature dependence
of magnetic hyperfine field, however, shows a sharp deviation from an expected Brillouin-like behavior for temperatures below
75 K. This additional magnetic interaction is believed to result from the polarization of Ce spin moments induced by the magnetic
field from Gd atoms. 相似文献
4.
The laws governing polarization of luminescence in the nanostructure Si/CaF2 upon polarization of the spins of the fluorine nuclei by means of optical excitation of charge carriers are considered theoretically.
The possibility of studying experimentally the properties of nuclear spins in analyzing luminescence is shown. The polarization
of luminescence is most informative in the range of excitation rates of charge carriers from 3⋅107 to 3⋅ 108 sec−1 with the CaF2 layer of thickness from 0.6 to 0.8 nm and optical excitation polarization degree of 0.1.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 524–529, July–August, 2005. 相似文献
5.
P. C. M. Yock 《International Journal of Theoretical Physics》2002,41(8):1591-1595
A previously proposed unified field theory of electro-strong interactions requires two scales of length within hadrons, 10–15 and 10–18 m respectively, and the onset of new phenomena at the shorter scale. Studies at the HERA electron–proton collider at the shorter scale have revealed a possible excess of high-transverse momentum events, as expected, with Q
2 30,000 (GeV/c2). The collider is currently being upgraded. This will permit a clearer test to be carried out. 相似文献
6.
The nuclear quadrupole interaction of 204mPb in lead oxides has been measured by γ–γ time differential perturbed angular correlation. Ab-initio calculations of the electric field gradients and X-ray diffraction allowed the assignment of the detected nuclear quadrupole
interactions to the different Pb sites in the PbO phases litharge and massicote as well as in Pb3O4. The TDPAC probe 204mPb was produced with a 204Bi/204mPb-generator at the home laboratory at the University of Leipzig. The use of a high performance liquid chromatography system
increased significantly the yield, the specific activity of 204mPb, and reduced the acidic concentration of the eluate. 相似文献
7.
Stefaan Cottenier Veerle Vanhoof Doru Torumba Valerio Bellini Mehmet Çakmak Michel Rots 《Hyperfine Interactions》2004,158(1-4):9-18
For some years already, ab initio calculations based on Density Functional Theory (DFT) belong to the toolbox of the field of hyperfine interaction studies.
In this paper, the standard ab initio approach is schematically sketched. New features, methods and possibilities that broke through during the past few years
are listed, and their relation to the standard approach is explained. All this is illustrated by some highlights of recent
ab initio work done by the Nuclear Condensed Matter Group at the K.U.Leuven. 相似文献
8.
Nobuhiro Yamanaka 《Hyperfine Interactions》2000,127(1-4):129-132
The Fermi contact parameter which represents hyperfine structure (hfs) has been accurately calculated for the ground state
of the 9Be+ ion in a previous paper. In the present paper, the calculated parameter is compared with a high precision measurement to
derive the hfs anomaly (the Bohr-Weisskopf effect), which is caused by nuclear magnetization distribution. The obtained hfs
anomaly shows a satisfactory agreement with the result of a nuclear shell model calculation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
The (Na+) Sternheimer antishielding factor γ∞ (Na+) was determined by 23Na NMR spectroscopy on sodium oxide chloride, Na3OCl. The quadrupolar coupling constant of the sodium ion in Na3OCl was determined to QCC=11.34 MHz, which presents the largest coupling constant of a sodium nucleus observed so far. Applying a simple point charge model, the largest principal value of the electric field gradient at the sodium site was calculated to Vzz=−6.76762·1020 V/m2. From these values we calculated the (Na+) Sternheimer antishielding factor to γ∞ (Na+)=−5.36. In sodium oxide, Na2O, we observed an isotropic chemical shift of δCS=55.1 ppm, referenced to 1 M aqueous NaCl (δ=0 ppm). 相似文献
10.
Mark Augath Patrick Heiler Stefan Kirsch Lothar R. Schad 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2009,200(1):134-136
The maintenance of a gradient of potassium and sodium ions across the cell membranes is essential for the physiological function of the mammal organism. The measurement of the spatial distribution of pathologically changing ion concentrations of 23Na and 39K with magnetic resonance imaging offers a promising approach in clinical diagnostics to measure tissue viability. Existing studies were focused mainly on 23Na imaging as well as spectroscopy with only one post-mortem study for 39K imaging. In this paper a triple resonant RF coil setup for the rat head at 9.4 T is presented for imaging of both nuclei (23Na and 39K) and the acquisition of anatomical proton images in the same experiment without moving the subject or the RF coil. In vivo MR images of 39K and 23Na in the rat brain were acquired as well as anatomical proton images in the same scanning session. 相似文献
11.
M. Assié F. de Oliveira Santos T. Davinson F. de Grancey L. Achouri J. Alcántara-Núñez T. Al Kalanee J.-C. Angélique C. Borcea R. Borcea L. Caceres I. Celikovic V. Chudoba D.Y. Pang C. Ducoin M. Fallot O. Kamalou J. Kiener Y. Lam A. Lefebvre-Schuhl G. Lotay J. Mrazek L. Perrot A.M. Sánchez-Benítez F. Rotaru M.-G. Saint-Laurent Yu. Sobolev N. Smirnova M. Stanoiu I. Stefan K. Subotic P. Ujic R. Wolski P.J. Woods 《Physics letters. [Part B]》2012
The unbound nucleus 18Na, the intermediate nucleus in the two-proton radioactivity of 19Mg, was studied by the measurement of the resonant elastic scattering reaction H(17Ne,p)17Ne performed at 4 A.MeV using a radioactive beam from the SPIRAL Facility. Spectroscopic properties of the low-lying states were obtained in an R-matrix analysis of the excitation function. 相似文献
12.
Y. Gangrsky K. Marinova S. Zemlyanoi M. Avgoulea J. Billowes P. Campbell B. Cheal B. Tordoff M. Bissell D. H. Forest M. Gardner G. Tungate J. Huikari H. Penttilä J. Äystö 《Hyperfine Interactions》2006,171(1-3):209-215
Collinear laser spectroscopy experiments on the ScII transition 3d4s
3D2→3d4p
3F3 at λ ≈ 363.1 nm were performed on the 42–46Sc isotopic chain using an ion guide isotope separator with a cooler–buncher. Isotope and isomer shifts and hyperfine structures
of five ground states and two isomers were measured. Preliminary results on the nuclear moments and charge radii changes deduced
from these measurements are reported. 相似文献
13.
The detection of Na in insulating samples by means of time of flight-secondary ion mass spectrometry (ToF-SIMS) depth profiling has always been a challenge. In particular the use of O2+ as sputter species causes a severe artifact in the Na depth distribution due to Na migration under the influence of an internal electrical filed. In this paper we address the influence of the sample temperature on this artifact. It is shown that the transport of Na is a dynamic process in concordance with the proceeding sputter front. Low temperatures mitigated the migration process by reducing the Na mobility in the target. In the course of this work two sample types have been investigated: (i) A Na doped PMMA layer, deposited on a thin SiO2 film. Here, the incorporation behavior of Na into SiO2 during depth profiling is demonstrated. (ii) Na implanted into a thin SiO2 film. By this sample type the migration behavior could be examined when defects, originating from the implantation process, are present in the SiO2 target. In addition, we propose an approach for the evaluation of an implanted Na profile, which is unaffected by the migration process. 相似文献
14.
Eliav U Keinan-Adamsky K Navon G 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,165(2):276-281
The splitting and the lineshape of the satellite transitions of 23Na are measures of the residual quadrupolar interaction and its distribution, which are related to the degrees of order and binding of sodium in biological tissues. However, these transitions are often masked by the stronger signals of the central transition and the isotropic sodium ions. A way to suppress the central signals, while preserving the lineshape and the intensity of the satellites, is suggested and tested on a liquid crystal and on bovine articular cartilage. 相似文献
15.
Silvia Olt Eva Krtz Ewald Komor Markus Rokitta Axel Haase 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,144(2):297
23Na NMR microimaging is described to map, for the first time, the sodium distribution in living plants. As an example, the response of 6-day-old seedlings of Ricinus communis to exposure to sodium chloride concentrations from 5 to 300 mM was observed in vivo using 23Na as well as 1H NMR microimaging. Experiments were performed at 11.75 T with a double resonant 23Na–1H probehead. The probehead was homebuilt and equipped with a climate chamber. T1 and T2 of 23Na were measured in the cross section of the hypocotyl. Within 85 min 23Na images with an in-plane resolution of 156 × 156 μm were acquired. With this spatial information, the different types of tissue in the hypocotyl can be discerned. The measurement time appears to be short compared to the time scale of sodium uptake and accumulation in the plant so that the kinetics of salt stress can be followed. In conclusion, 23Na NMR microimaging promises great potential for physiological studies of the consequences of salt stress on the macroscopic level and thus may become a unique tool for characterizing plants with respect to salt tolerance and salt sensitivity. 相似文献
16.
K. Okada I. Katayama M. Wada T. Nakamura S. Ohtani G. Marx S. Fujitaka J. Tanaka H. Kawakami 《Hyperfine Interactions》1998,115(1-4):209-213
In order to investigate the nuclear magnetic moments and the magnetization distributions in the unstable nuclei of 7,11Be, laser-microwave spectroscopy experiments using an ion-trap are under progress at IPNS, KEK-Tanashi. Status of the experiment
for the first unstable isotope 7Be is reported.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Due to a lack of at least 2 orders of magnitude in the amount of sample nuclei, single crystal surfaces are out of reach for
conventional NMR measurements. Our aim is to prove that highly polarized 129Xe provides a technique to overcome this restriction. Therefore an apparatus for polarizing 129Xe up to 0.7 by spin transfer from optically pumped Rb has been designed as well as an NMR spectrometer in combination with
a UHV chamber with sample cleaning, cooling and characterization abilities and a special manifold of glass stopcocks with
a liquid nitrogen cooled trap for dosing nitrogen free polarized Xe into the chamber onto the surface.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
18.
Historic mummies are a unique example of the human desire for immortality. Therefore, it is not surprising that modern diagnostic imaging has been widely applied to study them. Yet, magnetic resonance imaging (MRI) of such old remains has never been successfully achieved in a noninvasive way without rehydration. Furthermore, the impact of artificial mummification as done in ancient Egypt by natron (a blend of NaCl, Na(2)CO(3), NaHCO(3) and NaP(2)SO(4)) on human tissue with a particular focus on the sodium spatial distribution has never been addressed. Here, we show for the very first time completely noninvasive (1)H and (23)Na imaging of an ancient Egyptian mummified finger by nuclear magnetic resonance (NMR). Protons could be visualized by NMR only in the tissue close to surface and sodium primarily in the bone, while computer tomography images both, soft tissue and bone but does not distinguish between different chemical elements. The selective enrichment of sodium in the bone may by due to postmortem incorporation of (23)Na into the tissue by natron-based mummification because our reference measurement of a historical finger not subjected to artificial mummification showed no sodium signal at all. Our results demonstrate not only the general feasibility of nonclinical MRI to visualize historic dry human tissues but also shows the specific (1)H and (23)Na spatial distributions in such mummy tissue, which is particularly interesting for archeology and may open up a new application for MRI. 相似文献
19.
A. Inoyatov D.V. Filosofov V.M. GorozhankinA. Kovalík N.A. LebedevA.V. Lubashevskiy A.F. NovgorodovL.L. Perevoshchikov Ts. VylovE.A. Yakushev 《Journal of Electron Spectroscopy and Related Phenomena》2007
The low energy KLL Auger electrons of neon emitted after EC-decay of 22Na have been investigated with a 4 eV instrumental resolution using an electrostatic spectrometer and a solid state radioactive source. This is the first experimental investigation of the KLL Auger spectrum of neon from the solid state. Relative intensities and energies of all resolved spectrum components were determined. Measured absolute energy of the dominant KL2L3(1D) transition was found to be 824.5(19) eV, i.e. about 20 eV higher than that obtained in experiments with free Ne atoms. Within the experimental uncertainties, no influence of solid state effects on relative intensities of the KLL transitions was found. 相似文献
20.
在CO2激光功率为50—300W、扫描速度为20mm/s、激光散光斑为20mm照射条件下 ,诱导非 晶Fe735Cu1Nb3Si135B9带中发生结构重组,产生定量纳米α-F e(Si)晶相形成双相组织结构材料. 利用穆斯堡尔谱研究了非晶Fe735C u1Nb3Si135B9合金激光纳米化的 超精细结构. 实验结果表明,激光诱导非晶 Fe735Cu1Nb3Si135B 9纳米化后,其超精细磁场的分布随 着激光功率变 化由单峰向双峰变化,在高功率辐照时, 出现了双峰分布,并且峰位向高场移动. 高激光 功率辐照非晶Fe735Cu1Nb3Si135 sub>B9合金纳米晶化相有四种超精细结 构,即2个超精细磁场较小的初晶相和2个超精细磁场较大的纳米晶化相. 其中超精细磁场较 大(17—25MA/m)的α-Fe(Si)相为DO3结构.
关键词:
激光
纳米晶α-Fe(Si)
735Cu1Nb< sub>3Si135B9')" href="#">非晶Fe735Cu1Nb< sub>3Si135B9
超精细结构
超精细磁场 相似文献