Strong electron-phonon interaction

There are a large number of cases where the spectra of luminescence centers remain broad up to helium temperatures. In certain cases, this is explained by a strong electron-phonon interaction, but more often the inhomogeneous broadening, connected with several types of the same center presence, causes this. In such cases it is possible to simplify the spectrum by selective excitation of specific centers. 

A AH < kT has important consequences. As the temperature is lowered to where AHg, kT, strong electron-phonon interactions must manifest themselves. Direct evidence for mode softening and strong electron-phonon coupling in the internal Ty < T < 250 K has been provided by measurements of the Mdssbauer recoiless fraction and the X-ray Debye-Waller factor as well as of muon-spin rotation Therefore, it would be... 

Fig. 4a-c. Models for electron hopping correlated by electrostatic electron-electron interactions plus strong electron-phonon interactions for a valence ratio Fe /Fe = 1 (a) small pola-rons, (b) diatomic polarons, (c) small polaron coupled to slower (only one phase shown) dimerization... 

If strong electron-phonon interactions tend to stabilize a mean FeB-atom valence of 2.5 for X < 1.89, as is also indicated by the Mossbauer data (Xh < 10 s) and Eq. (1), then the valence distribution would be... 

Raman spectra indicate that phonons are coupled to electronic states in BaPb BijPj (53) and in Ba1.xKxBiOs (58). These studies do show a strong electron - phonon interaction is present in the superconducting phases, but do not prove that these modes are responsible for high Tc driven by a phonon - only mechanism. 

In discussing low temperature-dependent mobility, we should mention charge transport by polarons, an intermolecular phonon-assisted hopping process 24>25>. Polarons (charge carriers trapped in their polarization field) arise from a strong electron-phonon interaction where there is a weak overlap of wave functions of... 

There are three reasons why the temperature change can affect the tunnelling luminescence of radiation defects in wide-gap insulators characterized by a strong electron-phonon interaction ... 

Already in the seminal paper of Bednorz and Muller [1], the guide to look for systems with a high superconductive transition temperature (Tc), has been the presence of strong electron-phonon interactions. Such interaction has been known to exist in a wide class of perovskite type oxides. The authors mention [1] the vibronic Jahn-Teller polaron effect [2] in this context. They also emphasize the fact that the Cu2+-ion is a well-known Jahn-Teller system and this circumstance preserves significance in the physics of cuprate superconductors [3-7]. As a microscopic cause for ferroelectric ordering the interband vibronic hybridisation has been supposed [8-11] enlargening the view on perovskites as Jahn-Teller systems. 

The inelastic X-Ray scattering measurements [12] demonstrated a weak dispersion branch between 60 and 70 meV in the TA direction with E29 symmetry at the T point. The linewidth of this mode is about 20-j-28 meV along the TA direction, while along the TM direction it is below the experimental resolution. This points to the very strong electron-phonon interaction (EPI) for this particular lattice vibration mode. 

Gutfreund et al. [27] have proposed that strong electron-phonon interactions lead to an enhanced density of states, increasing Xs-... 

Theoretical models to explain the observed change in line width and line position as a result of transition to superconductivity quantitatively are based on strong electron-phonon interaction (Zeyher and Zwicknagel, 1990). 

Therefore, it is modulated by the intermolecular displacement occurring in a phonon motion. Photochemical aggregation reactions, such as dimerization or polymerization reactions, can be assisted by the occurrence of strong electron-phonon interaction in the reactive electronic state. This strong electron-phonon interaction creates a local lattice-deformation in the reactive (excited) electronic state. The deformation traps the electronic excitation and, at the same time, it may provide a local preformation of the product lattice if the distortion is along the reaction co-ordinate. Both these features assist a photochemical aggregation reaction. 

Even at the liquid-helium temperature the hfs of the most of excited crystal-field sublevels is masked by the spontaneous relaxation broadening. Strong electron-phonon interaction effects in CsCdBr3 Ln crystals originate from the specific density of phonon states that has large maxima in the low-frequency region (20-40 cm ) in the perfect crystal lattice (see Fig. 4 and Ref. 

Contrary to inorganic crystalline semiconductors, where charge is transported in general by electrons in the conduction band and holes in the valence band, in doped conjugated polymers charged solitons, polarons, and bipolarons act as charge carriers. These quasi-particles are the direct consequence of the strong electron-phonon interaction present in these quasi-one-dimensional polymers. 

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