We present calculations for the oscillator strength of the recombination of excitons bound to phosphorus donors in silicon. We show that the direct recombination of the bound exciton cannot account for the experimentally measured oscillator strength of the no-phonon line. Instead, the recombination process is assisted by an Umklapp process of the donor electron state. We make use of the empiric...

in this study, bio-based carbon nanotubes (cnts) have received considerable research attention due to their comparative advantages of high level stability, simplistic use, low toxicity and overall environmental friendliness. new potentials for improvement in heat transfer applications are presented due to their high aspect ratio, high thermal conductivity and special surface area. phonons have ...

We study the low-lying excitations of a quantum-Hall sample that has undergone edge reconstruction such that there exist three branches of chiral edge excitations. Among the interaction processes that involve electrons close to the three Fermi points is a new type of Umklapp-scattering process which has not been discussed before. Using bosonization and a refermionization technique, we obtain ex...

Results of statistical noise smoothing of the electron momentum distribution got by two-dimensional angular correlation of the electron-positron annihilation radiation technique on untwinned YBa2CuaO7_ ~ single crystals are reported. Two distinct signatures of the sheet of Fermi surface related to the CuO chains (the ridge) are resolved. The first occurs at second Umklapp processes, in agreemen...

We study the Hall effect in a system of weakly coupled Luttinger Liquid chains, using a Memory function approach to compute the Hall constant in the presence of umklapp scattering along the chains. In this approximation, the Hall constant decomposes into two terms: a high-frequency term and a Memory function term. For the case of zero umklapp scattering, where the Memory function vanishes, the ...

Within the framework of the quantized nesting model, we study the effect of umklapp scattering on the magnetic-field-induced spin-density-wave (SDW) phases which are experimentally observed in the quasi-one-dimensional organic conductors (TMTSF)2X. We discuss the conditions under which umklapp processes may explain the sign reversals (Ribault anomaly) of the quantum Hall effect (QHE) observed i...

We show that strong Luttinger correlations of the electron liquid in armchair carbon nanotubes significantly enhance the onset temperature of the putative twist Peierls instability and lead to its 1/R3 dependence on the tube radius. Depending on the values of the coupling constants the umklapp processes can either assist or compete with the twist instability. In the case of a competition the um...

We consider electrons on a two-leg triangular ladder at half filling and in an orbital magnetic field. In a two-band regime in the absence of the field, the electronic system remains conducting for weak interactions since there is no four-fermion umklapp term. We find that in the presence of the orbital field there is a four-fermion umklapp and it is always relevant for repulsive interactions. ...

The distribution of the electron scattering rate on the Fermi surface of a quasi-one-dimensional conductor is calculated for the electron-electron umklapp interaction. We nd that in certain regions on the Fermi surface the scattering rate is anomalously high. The reason for the existence of these \hot spots" is analogous to the appearance of the van Hove singularities in the density of states. ...