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1.
We report the experimental results of frequency-selective laser optical pumping and spin exchange of Cs with129Xe and131Xe in a high magnetic field of 11.74 T. Our results show that hyperpolarized129Xe and131Xe nuclear magnetic resonance (NMR) signals exhibit alternating phases when the laser frequency for pumping the cesium atoms is changed, which is explained on the basis of the high-field optical pumping of Cs. We obtain about 3% polarization of the129Xe. The electron-spin polarization of the Cs atoms has been measured to be about 22% with a simple NMR method. 相似文献
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G. Schatz X. L. Ding R. Fink G. Krausch B. Luckscheiter R. Platzer J. Voigt U. Wöhrmann R. Wesche 《Hyperfine Interactions》1990,60(1-4):975-989
Applications of hyperfine-interaction techniques, like NMR, PAC and Mößbauer spectroscopy, to well-characterized surfaces are discussed and the present knowledge of surface hyperfine fields is reviewed. Measurements of nuclear spin relaxation permit to extract the local density of electron states at the Fermi level of adsorbed alkali atoms. From the observed electric-field-gradient properties surface probe sites and diffusion processes can be inferred; the experimentally determined magnetic hyperfine fields give access to the electron-spin behaviour at magnetic surfaces. 相似文献
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Optical pumping nuclear magnetic resonance system rotating in a plane parallel to the quantization axis
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A model of an optical pumping nuclear magnetic resonance system rotating in a plane parallel to the quantization axis is presented. Different coordinate frames for nuclear spin polarization vector are introduced, and theoretical calculation is conducted to analyze this model. We demonstrate that when the optical pumping nuclear magnetic resonance system rotates in a plane parallel to the quantization axis, it will maintain a steady state with respect to the quantization axis which is independent of rotational speed and direction. 相似文献
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Kulik LV Grishin YA Dzuba SA Grigoryev IA Klyatskaya SV Vasilevsky SF Tsvetkov YD 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,157(1):61-68
The use of a rapid stepping of the magnetic field for investigation of electron dipole-dipole ESEEM in pulsed X-band ELDOR is described. The magnetic field jump, synchronized with a microwave pumping pulse, is positioned between the second and the third pulses of the stimulated echo pulse sequence. This echo is measured as a function of the delay between the first and the second pulses. The data are analyzed for a Fourier transform resulting in a Pake resonance pattern. To remove the electron-nuclear contributions to ESEEM, time traces with pumping were divided by those without. This resulted in complete elimination of electron-nuclear contributions, which is seen from the absence of peaks at nuclear frequencies and the similarity of results for protonated and deuterated solvents. For increasing the electron-electron modulation depth, a scanning of the magnetic field during the microwave pumping is proposed. The interspin distances and their distribution are determined for two long-chained (ca. 2 nm) nitroxide biradicals in glassy toluene and in frozen nematic liquid crystal 4-cyano-4'-pentyl-biphenyl. For the latter solvent, the alignment of the axis connecting two nitroxides in biradicals is quantitatively analyzed. 相似文献
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A sharp peak of magnetic susceptibility has been observed in the ferromagnetic resonance spectra of uniaxial magnetic films placed in a planar field directed orthogonal to the easy magnetization axis, along which a pumping high-frequency magnetic field has been oriented. The peak width is considerably narrower than the line width of the uniform ferromagnetic resonance, and its position in a field equal to the film anisotropy field does not depend on the pumping frequency. The nature of the peak is associated with a drastic increase in the static transverse susceptibility of the film in the vicinity of the anisotropy field. It is shown phenomenologically that the peak can be observed only for quality samples with small angular and amplitude dispersion of the uniaxial anisotropy. 相似文献
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We experimentally demonstrate that the decoherence of a spin by a spin bath can be completely eliminated by fully polarizing the spin bath. We use electron paramagnetic resonance at 240 GHz and 8 T to study the electron-spin coherence time T2 of nitrogen-vacancy centers and nitrogen impurities in diamond from room temperature down to 1.3 K. A sharp increase of T2 is observed below the Zeeman energy (11.5 K). The data are well described by a suppression of the flip-flop induced spin bath fluctuations due to thermal electron-spin polarization. T2 saturates at approximately 250 micros below 2 K, where the polarization of the electron-spin bath exceeds 99%. 相似文献
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For aromatic organic radicals, pulsed electron-electron double resonance (PELDOR) experiments at high magnetic fields offer
the possibility to achieve orientation-selective pumping and detection that could allow one not only to determine the distance
between paramagnetic species but also their relative orientation with respect to the interconnecting dipolar axis. We present
a PELDOR two-frequency setup that was introduced into our homebuilt 180 GHz pulsed electron paramagnetic resonance (EPR) spectrometer
and we discuss its technical and experimental features. The capability of 180 GHz PELDOR has been tested using the three-pulse
ELDOR sequence on the protein RNR-R2 (ribonucleotide reductase) fromEscherichia coli, which contains two tyrosyl radicals at a distance of 3.3 nm. At 180 GHz, orientation selectivity is observed and the modulation
frequency was found in good agreement with theoretical predictions, which take into account the relative orientation of the
radicals from X-ray data. 相似文献
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T. Yabuzaki T. Kinoshita K. Fukuda Y. Takahashi 《Zeitschrift für Physik B Condensed Matter》1995,98(3):367-369
In this paper, our recent works on the alkali atoms in superfluid helim (HeII) are reported. At first we mentions the laser-sputtering method for implantation, which is simple but is very efficient to produce various kinds of neutral atoms and molecules in HeII. Secondly, we report on the laser spectroscopy of alkali atoms in HeII. Optical excitation and emission spectra are found to be roughly explained by a spherical atomic bubble model, but the spectra corresponding to the D2 lines indicate the quadrupole oscillation of the bubble shape. Optical pumping by a circularly polarized laser beam is found to produce perfect polarization, for both electron and nuclear spins. Using the rf-optical double resonance techniques, the magnetic and hyperfine resonances are observed. It is discussed also about the phenomena which have observed in the experiments done so far but have not been fully explained. 相似文献
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A.N. Zelenski V. Klenov S.A. Kokhanovski V. Zoubets G. Dutto C.D.P. Levy G.W. Wight J. Alessi Y. Mori 《Hyperfine Interactions》2000,127(1-4):475-479
Optically-Pumped Polarized Ion Sources (OPPIS) are based on polarization transfer collisions between hydrogen (or deuterium)
ions and an optically-pumped electron spin polarized alkali metal vapor. The results of studies on optical pumping of high
density alkali metal vapour and spin exchange and charge-exchange polarization transfer collisions are discussed. The results
of high current OPPIS development for Relativistic Heavy Ion Collider (RHIC), BNL and HERA, DESY are also presented.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
11.
We demonstrate theoretically that it is possible to manipulate electron or hole spins all optically in semiconducting carbon nanotubes. The scheme that we propose is based on the spin-orbit interaction that was recently measured experimentally; we show that this interaction, together with an external magnetic field, can be used to achieve optical electron-spin state preparation with a fidelity exceeding 99%. Our results also imply that it is possible to implement coherent spin rotation and measurement using laser fields linearly polarized along the nanotube axis, as well as to convert spin qubits into time-bin photonic qubits. We expect that our findings will open up new avenues for exploring spin physics in one-dimensional systems. 相似文献
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We consider a four-level model for alkali metal atoms with optical pumping by nonresonant light under conditions when magnetic
dipole transitions are induced between energy sublevels of the hyperfine structure in the ground state. We present the dependences
of the observed signal as a function of the frequency detuning of the applied rf fields relative to the resonant value, calculated
in the density matrix formalism. We note the absence of a light shift in the radiofrequency-optical resonance signal, independent
of the amplitude of the rf field and the optical and thermal relaxation rates. We show that when using a modulation technique
for phase detection of the signal, its maximum discrimination ability is observed under conditions for simultaneous modulation
of the pump light intensity and the frequency of the rf field, which in principle does not occur in the classical two-level
model for optically oriented atoms in magnetic resonance.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 326–329, May–June, 2006. 相似文献
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Akhtar W Filidou V Sekiguchi T Kawakami E Itahashi T Vlasenko L Morton JJ Itoh KM 《Physical review letters》2012,108(9):097601
Pulsed electron paramagnetic resonance spectroscopy of the photoexcited, metastable triplet state of the oxygen-vacancy center in silicon reveals that the lifetime of the m(s)=±1 sublevels differs significantly from that of the m(s)=0 state. We exploit this significant difference in decay rates to the ground singlet state to achieve nearly ~100% electron-spin polarization within the triplet. We further demonstrate the transfer of a coherent state of the triplet electron spin to, and from, a hyperfine-coupled, nearest-neighbor (29)Si nuclear spin. We measure the coherence time of the (29)Si nuclear spin employed in this operation and find it to be unaffected by the presence of the triplet electron spin and equal to the bulk value measured by nuclear magnetic resonance. 相似文献
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Zorko A Jeglič P Potočnik A Arčon D Balčytis A Jagličić Z Liu X Tchougréeff AL Dronskowski R 《Physical review letters》2011,107(4):047208
We have investigated the magnetic properties of CuNCN, the first nitrogen-based analog of cupric oxide CuO. Our muon-spin relaxation, nuclear magnetic resonance, and electron-spin resonance studies reveal that classical magnetic ordering is absent down to the lowest temperatures. However, a large enhancement of spin correlations and an unexpected inhomogeneous magnetism have been observed below 80 K. We attribute this to a peculiar fragility of the electronic state against weak perturbations due to geometrical frustration, which selects between competing spin-liquid and more conventional frozen states. 相似文献