排序方式: 共有17条查询结果,搜索用时 15 毫秒
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H.P. Fredricksen M. Levy M. Tachiki M. Ashkin J.R. Gavaler 《Solid State Communications》1983,48(10):883-885
Nine NbN films ranging in thickness from 0.02 to 0.03 μm were studied by measuring the temperature dependence from 1.5 K to over 20 K of the ultrasonic attenuation of 700 MHz surface acoustic waves. The resulting curves did not fit the predictions of BCS. When the curves were numerically inverted to show the temperature dependence that the superconducting energy gap would need to have to produce the observed attenuation, they were found to be nearly constant at a value less than half of the BCS value. An analysis prompted by the Anderson theories of 2-D localizations shows the attenuation per film thickness to be proportional to the logarithm of the thickness. 相似文献
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The class of realn × n matricesM, known asK-matrices, for which the linear complementarity problemw – Mz = q, w 0, z 0, w
T
z =0 has a solution wheneverw – Mz =q, w 0, z 0 has a solution is characterized for dimensionsn <4. The characterization is finite and practical. Several necessary conditions, sufficient conditions, and counterexamples pertaining toK-matrices are also given. A finite characterization of completelyK-matrices (K-matrices all of whose principal submatrices are alsoK-matrices) is proved for dimensions <4.Partially supported by NSF Grant MCS-8207217.Research partially supported by NSF Grant No. ECS-8401081. 相似文献
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S. Lederer H. Winter HP. Winter F. Aumayr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):505-511
The energy loss of hydrogen atoms with energies of 400
eV and 1 keV is studied in coincidence with the number of emitted
electrons during grazing scattering from atomically clean and flat
KI(001) and LiF(001) surfaces. The energy loss spectra for
specific numbers of emitted electrons are analyzed in terms of a
binary interaction model based on the formation of transient
negative ions via local capture of valence band electrons from
anion sites. Based on computer simulations we derive for this
interaction scenario probabilities for the production of surface
excitons, for electron loss to the conduction band of KI, for
emission of electrons, and for formation of negative hydrogen
ions. The pronounced differences of data obtained for the two
surfaces are attributed to the different electronic structures of
KI and LiF. 相似文献
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A compact 14.5GHz electron cyclotron resonance (ECR) ion source for the production of slow, multiply charged ions has been constructed,with the plasma-confining magnetic field produced exclusively by permanent magnets.Microwave power of up to 175W in the frequency range from 12.75 to 14.SGHz is transmitted from ground potential via a PTFE window into the water-cooled plasma chamber which can be equipped with an aluminum liner.The waveguide coupling system serves also as biased electrode,and two remotely-controlled gas inlet valves connected via an insulating break permit plasma operation in the gas- mixing mode.A triode extraction system sustains ion acceleration voltages between 1kV and 10kV.The ECR ion source is fully computer-controlled and can be remotely operated from any desired location via Ethernet. 相似文献
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The electron-phonon contribution to the ultrasonic attenuation coefficient of a 0.5 μm Nb3Ge film has been measured using 1.2 GHz surface acoustic waves. Analysis of the attenuation data shows that the largest part of the film has a superconducting transition near the bulk transition temperature, 18 K, even though the total film has a high transition temperature, namely 21.5 K. The electron mean free path is calculated from the electron-phonon attenuation data and is found to be an order of magnitude higher than expected for high transition temperature Nb3Ge films. 相似文献
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This paper constructs a decreasing lexicographic list of necklaces of length n in beads of k colors. This list, somewhat modified, produces a k-ary de Bruijn sequence of length kn. 相似文献
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H.P. Fredricksen H.L. Salvo M. Levy R.H. Hammond T.H. Geballe 《Physics letters. A》1980,75(5):389-391
The attenuation of 660 MHz surface acoustic waves propagating in a thin film of Nb3Sn 5000 Å thick has been measured as a function of temperature from 4.2 K to 16 K. The A 15 Nb3Sn, electron-beam codeposited on YZ lithium niobate and annealed at 700°C, was studied using 5.1 μm wavelength interdigital electrodes. The film revealed a transition temperature of 14.2 ± 0.1 K and using the BCS theory, an energy gap 2Δ(0) = 3.5 kBTc. 相似文献
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