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51.
E. V. Yakovenko M. Gauthier A. Polian 《Journal of Experimental and Theoretical Physics》2004,98(5):981-985
Lattice vibrations of the wurtzite-type AIN have been studied by Raman spectroscopy under high-pressure up to the phase transition to the rock salt structure at 20 GPa. Five fundamental bands E 2 2 , A1(TO), E1(TO), A1(LO), and E1(LO) have a strong, positive pressure shift, whereas the shift of the low-frequency E 2 1 band is weakly positive. We have found that the bond-bending mode has a positive mode Grüneisen parameter γi = 0.04, which is qualitatively consistent with the recently reported value γi = 0.12 [21]. Thus, we confirm that AIN remains stable with respect to the bond-bending mode, while in most tetrahedral semiconductors, bond-bending modes soften on compression. Experimental results are compared with the first-principle calculations. 相似文献
52.
Winé G Matta J Tessonnier JP Pham-Huu C Ledoux MJ 《Chemical communications (Cambridge, England)》2003,(4):530-531
Beta zeolite supported on silicon carbide, with high thermal conductivity and high mechanical strength, was successfully used as an active and stable catalyst for Friedel-Crafts reactions in a fixed bed configuration. 相似文献
53.
We describe the operating characteristics of a new type of quantum oscillator that is based on a two-photon stimulated emission process. This two-photon laser consists of spin-polarized and laser-driven 39K atoms placed in a high-finesse transverse-mode-degenerate optical resonator and produces a beam with a power of approximately 0.2 microW at a wavelength of 770 nm. We observe complex dynamical instabilities of the state of polarization of the two-photon laser, which are made possible by the atomic Zeeman degeneracy. We conjecture that the laser could emit polarization-entangled twin beams if this degeneracy is lifted. 相似文献
54.
We describe two experiments in which we investigate the synchronization of coupled periodic oscillators. Each experimental system consists of two identical coupled electronic periodic oscillators that display bursts of desynchronization events similar to those observed previously in coupled chaotic systems. We measure the degree of synchronization as a function of coupling strength. In the first experiment, high-quality synchronization is achieved for all coupling strengths above a critical value. In the second experiment, no high-quality synchronization is observed. We compare our results to the predictions of the several proposed criteria for synchronization. We find that none of the criteria accurately predict the range of coupling strengths over which high-quality synchronization is observed. (c) 2000 American Institute of Physics. 相似文献
55.
G. Couturier J.P. Aimé J. Salardenne R. Boisgard A. Gourdon S. Gauthier 《Applied Physics A: Materials Science & Processing》2001,72(7):S47-S50
Experiments performed using NC-AFM on a pure graphite surface suggest that the mechanical deformation of the surface under test is able to explain the observed damping signal. A simple analytical model has been built to evaluate the damping signal in terms of the mechanical properties of the surface, the amplitude of the oscillation and the tip-surface distance. Besides these experiments and a model, a virtual NC-AFM microscope has been developed, based on the Matlab language. This virtual machine allows some assumptions of the analytical model to be validated or invalidated, since no approximations are made in solving the nonlinear differential equation which controls the tip-surface interaction and the NC-AFM electronic loop is included. 相似文献
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Decremps F Belhadi L Farber DL Moore KT Occelli F Gauthier M Polian A Antonangeli D Aracne-Ruddle CM Amadon B 《Physical review letters》2011,106(6):065701
The cerium γ?α transition was investigated using high-pressure, high-temperature angle-dispersive x-ray diffraction measurements on both poly- and single-crystalline samples, explicitly addressing symmetry change and transformation paths. The isomorphic hypothesis of the transition is confirmed, with a transition line ending at a solid-solid critical point. The critical exponent is determined, showing a universal behavior that can be pictured as a liquid-gas transition. We further report an isomorphic transition between two single crystals (with more than 14% of volume difference), an unparalleled observation in solid-state matter interpreted in terms of dislocation-induced diffusionless first-order phase transformation. 相似文献
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