Inelastic electron-phonon scattering

As described in previous works [2, 3], the o(I) below 4.2 K follows a dependence (see Eq. (3.2)) in both the parallel and the perpendicular directions to the chain axis in oriented I-(CH)x samples. The dependence indicates that the contribution from e-e interactions plays a dominant role at very low temperatures. This is also consistent with the enhanced negative contribution to magnetoconductance (MC), as explained in detail in the next section. For the intermediate temperature range (4-40 K), where scattering mechanism, for the parallel and the perpendicular directions to the chain axis [1131,1133]. This is also consistent with the enhanced positive contribution to MC at temperatures above 4 K. This suggests that both interaction and localization play dominant roles in o(7) at low temperatures in metallic (CH) r samples. 

Figure 2.7 Artistic view of electron-phonon scattering. Lattice motions involving the displacement of polar modes can scatter the electron inelastically. The polar fluctuations create dipolar fields that can modulate the electron distribution. The electron responds to these stochastic fluctuations in local fields with a change in its energy and effective momentum transfer to the lattice. This process is depicted by comparing (a) and (b) to visualise the motion of the lattice atoms, leading to a change in direction or momentum of the electron from its initial path shown in (a).

These carbon films are considered as dirty metals whose temperature dependence of conductivity would depend on the inelastic mean free path 1 T) [76]. Now, when electron-phonon scattering is dominant, the mean free path will follow the relationship of 1, T) T. At low temperatures (for T < where 0 is the Debye temperature of the material) for both electron-electron scattering and electron-phonon scattering. 

Static defects scatter elastically the charge carriers. Electrons do not loose memory of the phase contained in their wave function and thus propagate through the sample in a coherent way. By contrast, electron-phonon or electron-electron collisions are inelastic and generally destroy the phase coherence. The resulting inelastic mean free path, Li , which is the distance that an electron travels between two inelastic collisions, is generally equal to the phase coherence length, the distance that an electron travels before its initial phase is destroyed ... 

Whelan, M.J. (1965) Inelastic scattering of fast electrons by crystals - II. Phonon scattering, Applied Phys., 36, 2103-2110. 

The commonly used scheme of energy relaxation in RGS includes some stages (Fig.2d, solid arrows). Primary excitation by VUV photons or low energy electrons creates electron-hole pairs. Secondary electrons are scattered inelastically and create free excitons, which are self-trapped into atomic or molecular type centers due to strong exciton-phonon interaction. 

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. 

The nonadiabatic (nonsecular) contributions T, and T34 to the coherence decay are caused by inelastic 7 ,-type processes. Equation (41b) shows that these inelastic scattering processes are induced by anharmonic-ity (k ) in the ground state and a combination of anharmonicity and electron-phonon coupling (Vg ) in the excited state. Here describes the decay (creation) of the pseudolocalized phonon into (from) two band phonons. The relevant part of is in (39) the last term, which describes in the excited state the exchange of a pseudolocalized phonon with a band phonon. At low temperature (/c7 phonon scattering processes in the ground and excited state. 

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