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Arno Müller 《Fresenius' Journal of Analytical Chemistry》1933,95(4-6):166-167
Ohne Zusammenfassung 相似文献
56.
Striped high-T(c) superconductors such as La(2-y-x)Nd(y)Sr(x)CuO(4) and La(2-x)Ba(x)CuO(4) near x = 1/8 show a fascinating competition between spin and charge order and superconductivity. A theory for these systems therefore has to capture both the spin correlations of an antiferromagnet and the pair correlations of a superconductor. For this purpose we present here an effective Hartree-Fock theory incorporating both electron pairing with finite center-of-mass momentum and antiferromagnetism. We show that this theory reproduces the key experimental features such as the formation of the antiferromagnetic stripe patterns at 7/8 band filling or the quasi-one-dimensional electronic structure observed by photoemission spectroscopy. 相似文献
57.
The role of extra-framework and framework aluminium in wet-ion exchanged Fe-ZSM5 has been studied using 29Si NMR and 27Al triple quantum magic angle spinning (3QMAS) NMR. A series of samples were studied, the parent material, the wet ion exchanged Fe-ZSM5 and Fe-ZSM5 that has been used in the decomposition of N2O with varying reaction conditions. Various framework and extra-framework aluminium species have been identified. It was found that cationic Fe species prefer to replace the Brønsted acid protons in their charge balancing role at those aluminium sites associated with the largest quadrupolar product. The framework aluminium atoms that pertain to the smaller quadrupolar product, which are either charge balanced by extra-framework aluminium or a proton, are much less prone to exchange. In the catalytic decomposition of N2O it seemed that water present in small amounts enhances the catalytic activity. However, water also decreases the long term stability and performance by dealuminating the zeolite framework. With a high amount of water present, Fe-ZSM5 was destabilised and catalytically inferior. 相似文献
58.
E. Man�� J. A. Behr J. Billowes T. Brunner M. Brodeur F. Buchinger J. E. Crawford J. Dilling S. Ettenauer C. D. P. Levy A. Voss M. R. Pearson 《Hyperfine Interactions》2011,199(1-3):357-363
Collinear laser spectroscopy with reverse-extracted cooled bunched beams was performed at TRIUMF with radioactive ion beams. Surface-ionized 78,78mRb ions were injected into TITAN??s cooler-buncher, and reverse-extracted to the laser beam line. There they were neutralised and excited with a counter-propagating laser beam. The fluorescence signal from the D 2 line was recorded with a photomultiplier tube. The cooler provided typically 50 ion bunches per second, with each bunch containing approximately 105 ions, temporally distributed with a 1.6 ??s width. A hardware gate was set on the signal, suppressing the background by four orders of magnitude. 相似文献
59.
A. Gorelov J.A. Behr D. Melconian M. Trinczek P. Dubé O. Häusser U. Giesen K.P. Jackson T. Swanson J.M. D'Auria M. Dombsky G. Ball L. Buchmann B. Jennings J. Dilling J. Schmid D. Ashery J. Deutsch W.P. Alford D. Asgeirsson W. Wong B. Lee 《Hyperfine Interactions》2000,127(1-4):373-380
Laser trapping and cooling techniques are now being applied to the study of nuclear β-decay at several labs. A magneto-optical
trap (MOT) provides a localized source of atoms suspended in space, so the low-energy recoiling nuclei can freely escape and
be detected in coincidence with the β. This allows reconstruction of the neutrino momentum, and the deduction of the β-v correlation in a more direct fashion than previously possible. In addition, the nuclei can be polarized by atomic techniques,
opening a new class of spin correlation measurements to test the degree to which parity is maximally violated in the weak
interaction. Our present experiment has detected several hundred thousand recoil-β+ coincidences from the 0+ → 0+ pure Fermi decay of 38mK, produced at the on-line isotope separators TISOL and ISAC at TRIUMF. Our goal is to set constraints on non-Standard Model
scalar bosons competitive with high-energy colliders and more conventional β-v correlation experiments.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
60.
S. A. Waksman K. R. Stevens A. Rippel G. Behr H. Wiangke Pfeiffer R. R. Le G. Worsley und F. J. Nutman 《Fresenius' Journal of Analytical Chemistry》1934,96(3-4):151-155
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