共查询到19条相似文献,搜索用时 109 毫秒
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不同边界条件下一维双原子链的晶格振动 总被引:10,自引:2,他引:8
在自由边界条件和驻波边界条件下,讨论分析了一维双原子链晶格振动的振动模和色散关系,并与周期性边界条件下的结果进行了比较;明确了在不同边界条件下讨论实际原子链晶格振动的振动模和色散关系,其结果是相同的。 相似文献
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讨论晶格的光频支格波对晶格热容的贡献,得到了这部分的热容的表达式。在低温极限情况下,光频支格波对晶格热容的贡献很小,可以忽略,只有频率较低的声频支格波对晶格热容有重要贡献;在高温情况下,复式 和中光频支格波对晶格热容有重要贡献,高温情况下的结果与杜隆-珀蒂定律给出的经典数值一致,该定律在高温时与实际实验符合得很好。 相似文献
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V. A. Zuikov A. Yu. Vorobyev V. S. Lobkov A. V. Leontiev K. M. Salikhov V. V. Samartsev G. M. Safiullin 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(7):1019-1021
Some results of femtosecond echo experiments on polyvinylbutyral polymer films doped with phtalocyanine molecules at high (up to room) temperatures are reported. Special attention is paid to the stimulated femtosecond photon echo (SFPE), which was observed in a solid-state medium at room temperature for the first time. A decay curve of the SFPE signal has been obtained and theoretically analyzed. The results of the analysis indicate that the random interaction between impurity molecules and quasi-localized low-frequency vibration modes in an amorphous matrix plays the dominant role in the character of optical dephasing at high temperatures. 相似文献
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The analytical equations of the transfer matrix method are further derived for the multi-coupled vibration of flexural and longitudinal waves in a periodic dual-layered beam structure with connection branches, with full consideration given to the flexural and longitudinal motions that are tri-coupled at each connection. Measurements of mobilities at the junctions on the uni-layered beam and the cross-layered beam are made. The numerical results agree well with the experimental results at all frequencies from 10 to 2000 Hz, which verifies the theoretical methodology for the multi-coupled vibration in a finite dual-layered beam. The cross-layer energy transmission is calculated, which reveals that the transmitted longitudinal energy is enhanced not only at the longitudinal resonant modes but also at the flexural resonant modes of the connection branches due to the structural wave coupling. The flexural energy is excited by wave coupling and becomes stronger at the longitudinal resonant modes and the flexural resonant modes of the connection branches. The cross-layer vibration motions from coupled waves in the branches can be effectively controlled by the attached cantilevers with mass at the resonance modes. This method can be used to control the structure-borne sound transmission in multi-layer beam structures. 相似文献
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The problem of bound polarons in quantum dot quantum well (QDQW)
structures is studied theoretically. The eigenfrequencies of bulk
longitudinal optical (LO) and surface optical (SO) modes are derived
in the framework of the dielectric continuum approximation. The
electron--phonon interaction Hamiltonian for QDQW structures is
obtained and the exchange interaction between impurity and
LO-phonons is discussed. The binding energy and the trapping energy
of the bound polaron in CdS/HgS QDQW structures are calculated. The
numerical results reveal that there exist three branches of
eigenfrequencies of surface optical vibration in the CdS/HgS QDQW
structure. It is also shown that the binding energy and the trapping
energy increase as the inner radius of the QDQW structure decreases,
with the outer radius fixed, and the trapping energy takes a major
part of the binding energy when the inner radius is very small. 相似文献
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M. Stojanovi?A. Maluckov Lj. Had?ievskiB.A. Malomed 《Physica D: Nonlinear Phenomena》2011,240(18):1489-1496
Fundamental solitons pinned to the interface between three semi-infinite one-dimensional nonlinear dynamical chains, coupled at a single site, are investigated. The light propagation in the respective system with the self-attractive on-site cubic nonlinearity, which can be implemented as an array of nonlinear optical waveguides, is modeled by the system of three discrete nonlinear Schrödinger equations. The formation, stability and dynamics of symmetric and asymmetric fundamental solitons centered at the interface are investigated analytically by means of the variational approximation (VA) and in a numerical form. The VA predicts that two asymmetric and two antisymmetric branches exist in the entire parameter space, while four asymmetric modes and the symmetric one can be found below some critical value of the inter-lattice coupling parameter—actually, past the symmetry-breaking bifurcation. At this bifurcation point, the symmetric branch is destabilized and two new asymmetric soliton branches appear, one stable and the other unstable. In this area, the antisymmetric branch changes its character, getting stabilized against oscillatory perturbations. In direct simulations, unstable symmetric modes radiate a part of their power, staying trapped around the interface. Highly unstable asymmetric modes transform into localized breathers traveling from the interface region across the lattice without significant power loss. 相似文献
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The modes of vibration of an elastic plate are usually divided into propagating and nonpropagating kinds. While nonpropagating modes characterize local vibration nearby a perturbation source, which can be either an external force or a geometrical discontinuity, propagating modes carry energy along the waveguide and account for the vibration far away from the perturbation source. In this paper, by considering that the modes of an absorbing plate are always propagating, it is shown that each elastic mode consists of propagating and nonpropagating branches, which turn into a single propagating mode as soon as internal absorption is considered. Moreover, it is shown how introducing a little material damping leads to a rigorous differentiation of elastic modes when they are connected. A similar result can be obtained by loading the plate with a light fluid [Rokhlin et al., J. Acoust. Soc. Am. 85, 1074-1080 (1989)]. 相似文献
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For one-dimensional conductors with half- filled band, the lattice vibration spectra, both acoustic and optical branches, are obtained analytically in the dimerized state. It is shown that, there exist not only a gap in k=π/2 Brillouin zone boundary,but also a gap between the optical and acoustic phonon branches when the electron-lattice coupling cons- taut λ is Larger than λc(=0.21). Then,the frequency of the Staggered mode around solitons can be described analytically for any coupling constant λ. 相似文献
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The optical feedback characteristics in a short cavity dual modes HeNe laser are studied under different modes strength condition. Modes competition can be obviously observed during optical feedback. The whole laser intensity curve has intensity branches and its leaning direction is related to the moving direction of the external feedback mirror. There are two cross points at different voltage levels between the two orthogonally polarized lights in a period of the optical feedback fringe and the order that the cross points come out is different when the feedback mirror moves at different direction which can be used for direction discrimination. Sometimes there are two peaks of the same size in a period of the optical feedback curve which can be used to improve the resolution of an optical feedback system. 相似文献