Phonon nanostructured materials

Redistribution of the phonon density of states due to local deformations caused by an introduction of an impurity Ln ion is of primary importance for electron-phonon interaction effects. In particular, for Pr CsCdBr3 the effective electron-phonon coupling is strongly suppressed due to a local increase of elastic forces in the activated crystal and the corresponding enhancement of correlation between displacement of the impurity Ln ion and its neighbors. When dealing with nanostructured materials, it is important to take into account... 

We have analyzed the influence of the annealing temperature, structural disorder, and the frequency of a continuous excitation laser radiation Vl on the first- and the second-order Raman spectra of several nanostructured carbon materials including single-wall carbon nanotubes (SWCNT), SWCNT-polymer composites, and nanostructured single-crystalline graphites. Consideration of the high-order nonlinear effects in Raman spectra and anharmonicity of characteristic Raman bands (such as G, G, and D modes) provides important information on the vibration modes and collective (phonon-like) excitations in such ID or 2D confined systems... 

Phonon-assisted tunneling (PhAT) model has been shown to explain properly nonlinear current-voltage characteristics and temperature dependence of conductivity in carbon nanotubes and other nanostructures of organic materials [1,2], In this paper, we want to show that this model is workable in explanation of I-V characteristics of inorganic nanodevices (Bi xSbx)2Te3 nanowires measured in a wide temperature range, 1.75-350 K, by Xiao et al. [3] and ZnSnOs nanowires presented in [4]. 

For nanostructures, difficulties in determining the correct frequency shift arise from other factors which have an influence on the peak frequency, like strain and phonon confinement. The strain-induced shift of the optical phonon frequencies in superlattices and quantum wells can be estimated by the difference in the lattice constants of the materials. To determine the composition-dependent shift in a system with two-mode behavior, which shows strong phonon confinement, the difference in the frequency positions of the two LO-phonon modes is used, which is confinement independent in many cases [92,101,104,105]. 

From fundamental aspects, nanosized structures exhibit quite different properties compared to their parent bidk-like materials (Norris and Bawendi 1995). Thus, the electronic density of states related to nanoparticles exhibits quantified features in similar way as the optical emission spectra might be related to those of artificial atoms (Kagan et al. 1996). The quantum confinement effect alters both electrons and phonons mean-free paths in the nanostructures. The consequence on the electronic features lies in the bandgap widening for semiconducting... 

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