Free electron model

About: Free electron model is a research topic. Over the lifetime, 4678 publications have been published within this topic receiving 103535 citations.

Optical coherence transfer mediated by free electrons

Abstract: We theoretically investigate the quantum-coherence properties of the cathodoluminescence (CL) emission produced by a temporally modulated electron beam. Specifically, we consider the quantum-optical correlations of CL produced by electrons that are previously shaped by a laser field. Our main prediction is the presence of phase correlations between the emitted CL field and the electron-modulating laser, even though the emission intensity and spectral profile are independent of the electron state. In addition, the coherence of the CL field extends to harmonics of the laser frequency. Since electron beams can be focused to below 1 A, their ability to transfer optical coherence could enable the ultra-precise excitation, manipulation, and spectrally resolved probing of nanoscale quantum systems.

Bloch waves and scattering by impurities

Abstract: The reciprocal lattice representation of the Green function method used by Ziman in 1965 for calculating band structures is derived. It is shown that the coefficients νg introduced by Ziman are the Fourier coefficients of the wave function outside the potential wells of a `muffin tin' lattice. The relationship between the method and the augmented plane wave approach is discussed. An exact formulation of the problem of Bloch wave scattering from an impurity potential is given. Simple approximations are suggested for tightly bound electrons for nearly free electrons and for d-band electrons.

Direct determination of free exciton binding energy from phonon-assisted luminescence spectra in GaN epilayers

Abstract: Investigation of variable-temperature longitudinal optical (LO) phonon-assisted luminescence spectra of free excitons and free electrons in heteroepitaxial GaN thin films has been conducted. It is found that thermal broadening of the LO phonon-assisted photoluminescence peaks is much slower than those of the peaks of their parents so that the first-order LO peaks of the free exciton transition and the band-to-band transition can be well resolved even at room temperature, leading to a direct determination of the band A free exciton binding energy as 25.4±0.9 meV. At the same time, we demonstrate that the simple hydrogenlike model still is a good approximation to describe the energy level structure of free excitons in GaN.

Propagation and stability of intense laser pulses in partially stripped plasmas

Abstract: The propagation and stability of intense laser pulses in a partially stripped plasma, i.e., in the presence of free and bound electrons, is analyzed. The presence of bound electrons is shown to significantly alter the propagation and stability of intense laser pulses. The bound electrons are represented by a linear and nonlinear susceptibility, while the free electrons, which can support plasma waves, are treated nonlinearly. In the presence of both free and bound electrons, an atomic modulation instability develops that can have a growth rate substantially higher than either the conventional relativistic modulational instability or the forward Raman instability. Bound electrons can also greatly enhance the filamentation instability. The backward Raman instability, however, is unaffected by bound electrons. {copyright} {ital 1997} {ital The American Physical Society}