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791.
E. S. Gladney T. E. Hakonson M. Muller 《Journal of Radioanalytical and Nuclear Chemistry》1984,84(2):423-429
This pape discusses the use, of stable Cs as an activatable tracer for measuring performance of plant root intrusion barriers for solid waste disposal site cover systems. Experiments conducted at small-scale demonstrate the effectiveness and practicality of the technique and suggest that the methodology has application to a better understanding of plant root ecology. 相似文献
792.
Single-crystal X-ray diffraction studies have been performed at low temperature (T=15 K) on the BaZnFe6O11 and BaCoFe6O11 (Y-type) room-temperature ferrimagnetic hexagonal ferrites. From the refined structures, we notice high thermal vibrations for the oxygen anions, especially for the O3 one which lies around the large Ba cation. From powder neutron diffraction at T=2 K we confirm the collinear Gorter model of the magnetic structure in the basal plane for BaZnFe6O11; the reductions of the magnetic moments located on the (6c*IV) and (6cIV) sites are discussed from superexchange qualitative considerations. 相似文献
793.
Jonckheere T Muller CA Kaiser R Miniatura C Delande D 《Physical review letters》2000,85(20):4269-4272
Coherent backscattering is a multiple scattering interference effect which enhances the diffuse reflection off a disordered sample in the backward direction. Classically, the enhanced intensity is twice the average background under well chosen experimental conditions. We show how the quantum internal structure of atomic scatterers leads to a significantly smaller enhancement. Theoretical results for double scattering in the weak localization regime are presented which confirm recent experimental observations. 相似文献
794.
Gwinner G Hoffknecht A Bartsch T Beutelspacher M Eklow N Glans P Grieser M Krohn S Lindroth E Muller A Saghiri AA Schippers S Schramm U Schwalm D Tokman M Wissler G Wolf A 《Physical review letters》2000,84(21):4822-4825
Radiative recombination (inverse photoionization) is believed to be well understood since the beginning of quantum mechanics. Still, modern experiments consistently reveal excess recombination rates at very low electron-ion center-of-mass energies. In a detailed study on recombination of F6+ and C6+ ions with magnetically guided electrons we explored the yet unexplained rate enhancement, its dependence on the magnetic field B, the electron density n(e), and the beam temperatures T( perpendicular) and T( ||). The excess scales as T(-1/2)( perpendicular) and, surprisingly, as T(-1/2)( ||), increases strongly with B, and is insensitive to n(e). This puts strong constraints on explanations of the enhancement. 相似文献
795.
Geer S Marriner J Martens M Ray RE Streets J Wester W Hu M Snow GR Armstrong T Buchanan C Corbin B Lindgren M Muller T Gustafson R 《Physical review letters》2000,84(4):590-593
A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on fifteen antiproton decay modes. The results are used to place limits on the characteristic mass scale m(X) that could be associated with CPT violation accompanied by baryon number violation. 相似文献
796.
Plettner C Ragnarsson I Schnare H Schwengner R Kaubler L Donau F Algora A de Angelis G Napoli DR Gadea A Eberth J Steinhardt T Thelen O Hausmann M Muller A Jungclaus A Lieb KP Jenkins DG Wadsworth R Wilson AN 《Physical review letters》2000,85(12):2454-2457
High-spin states in 72Br were studied with the EUROBALL III spectrometer using the 40Ca(40Ca,alpha3p1n) reaction. The negative-parity band observed in this experiment displays a signature inversion around spin I = 16. The interpretation within the cranked Nilsson-Strutinsky approach shows that this signature pattern is a signal of a substantial triaxial shape change with increasing spin where the nucleus evolves from a triaxial shape with rotation about the intermediate axis at low spin through a collective prolate shape to a triaxial shape but with rotation about the shortest principal axis at high spin. 相似文献
797.
Benedek R Alavi A Seidman DN Yang LH Muller DA Woodward C 《Physical review letters》2000,84(15):3362-3365
The relaxed atomic structure of a model ceramic/metal interface, 222MgO/Cu, is simulated, including lattice constant mismatch, using first principles local-density functional theory plane wave pseudopotential methods. The 399-atom computational unit cell contains 36 O and 49 Cu atoms per layer in accordance with the 7/6 ratio of MgO to Cu lattice constants. The atomic layers on both sides of the interface warp to optimize the local bonding. The interface adhesive energy is calculated. The interface electronic structure is found to vary appreciably with the local environment. 相似文献
798.
Schwaller P Groning P Schneuwly A Boschung P Muller E Blanc M Schlapbach L 《Ultrasonics》2000,38(1-8):212-214
Even though friction is one of the oldest problems in physics many aspects of friction processes are not clear today. We present an experimental setup, which permits the study of tribological systems by measuring the dissipated heat at the interface of two surfaces during a friction process with a time resolution of 1 ms. The apparatus is based on a standard ultrasonic wire-bond machine used in semiconductor industries to connect the internal semiconductor die to the external leads, but the standard bond wire is replaced by a thermocouple. To demonstrate the ability of the apparatus it will be shown that bond substrates used in semiconductor industries can be unequivocally characterized. 相似文献
799.
An FeBO3 single crystal was studied from 291 K up to the Neel temperature T(N) = 348.35 K by depth selective conversion electron Mossbauer spectroscopy in ultrahigh vacuum (10(-9) mbar). A new magnetic near-surface phase was found. Its thickness D diverges on approaching T(N) and gives a critical exponent for the correlation length of nu = 0.59(4). The phase boundary between the bulk and near-surface phase could be identified. 相似文献
800.
Seba P Rotter I Muller M Persson E Pichugin K 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(1):66-70
Numerical calculations for a microwave Sinai billiard coupled strongly to a lead are performed as a function of the coupling strength between billiard and lead. They prove the formation of different time scales in an open quantum system at large coupling strength. The short-lived collective states are formed together with many long-lived trapped states. 相似文献