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.

VII Interaction of Very Intense Light with Free Electrons

Abstract: Publisher Summary This chapter discusses the interaction of very intense light with free electrons. Thomson showed electron would oscillate in the presence of the electromagnetic wave, it would act as a source of dipole radiation itself, with the consequence that a definite fraction of the incident radiant energy flux would be removed from the electromagnetic wave and scattered into other directions. There is always an interest in the interaction of charged particles with electromagnetic waves. The chapter describes the experimental and theoretical aspects of the free electron–photon interaction that are non-trivially intensity dependent.

Ion temperature effects on magnetotail Alfvén wave propagation and electron energization

Abstract: A new 2-D self-consistent hybrid gyrofluid-kinetic electron model in dipolar coordinates is presented and used to simulate dispersive-scale Alfven wave pulse propagation from the equator to the ionosphere along an L = 10 magnetic field line. The model is an extension of the hybrid MHD-kinetic electron model that incorporates ion Larmor radius corrections via the kinetic fluid model of Cheng and Johnson (1999). It is found that consideration of a realistic ion to electron temperature ratio decreases the propagation time of the wave from the plasma sheet to the ionosphere by several seconds relative to a ρi=0 case (which also implies shorter timing for a substorm onset signal) and leads to significant dispersion of wave energy perpendicular to the ambient magnetic field. Additionally, ion temperature effects reduce the parallel current and electron energization all along the field line for the same magnitude perpendicular electric field perturbation.

Doping a semiconductor to create an unconventional metal

Abstract: Landau Fermi liquid theory, with its pivotal assertion that electrons in metals can be simply understood as independent particles with effective masses replacing the free electron mass, has been astonishingly successful. This is true despite the Coulomb interactions an electron experiences from the host crystal lattice, its defects, and the other ~1022/cm3 electrons. An important extension to the theory accounts for the behaviour of doped semiconductors1,2. Because little in the vast literature on materials contradicts Fermi liquid theory and its extensions, exceptions have attracted great attention, and they include the high temperature superconductors3, silicon-based field effect transistors which host two-dimensional metals4, and certain rare earth compounds at the threshold of magnetism5-8. The origin of the non-Fermi liquid behaviour in all of these systems remains controversial. Here we report that an entirely different and exceedingly simple class of materials - doped small gap semiconductors near a metal-insulator transition - can also display a non-Fermi liquid state. Remarkably, a modest magnetic field functions as a switch which restores the ordinary disordered Fermi liquid. Our data suggest that we have finally found a physical realization of the only mathematically rigourous route to a non-Fermi liquid, namely the 'undercompensated Kondo effect', where there are too few mobile electrons to compensate for the spins of unpaired electrons localized on impurity atoms9-12.

Quantum Entanglement and Modulation Enhancement of Free-Electron-Bound-Electron Interaction.

Abstract: The modulation and engineering of the free-electron wave function bring new ingredients to the electron-matter interaction. We consider the dynamics of a free-electron passing by a two-level system fully quantum mechanically and study the enhancement of interaction from the modulation of the free-electron wave function. In the presence of resonant modulation of the free-electron wave function, we show that the electron energy loss and gain spectrum is greatly enhanced for a coherent initial state of the two-level system. Thus, a modulated electron can function as a probe of the atomic coherence. We further find that distantly separated two-level atoms can be entangled through interacting with the same free electron. Effects of modulation-induced enhancement can also be observed using a dilute beam of modulated electrons.

Time-dependent Boltzmann kinetic model of x rays produced by ultrashort-pulse laser irradiation of argon clusters

Abstract: The Boltzmann equation and a detailed collisional-radiative model are solved simultaneously as a function of time to model the time-integrated x-ray spectra of the transient plasma produced by a high intensity ultrafast laser source. Level populations are calculated by solving the rate equations as a function of time using rate coefficients corresponding to a time varying electron energy distribution function (EEDF) determined by the solution to the Boltzmann equation. Electron-electron interactions are included through the solution of the Fokker-Planck equation. It is assumed that all the ions are initially in the Ne-like ground state due to the laser prepulse and that all free electrons have high energy (5 keV) from the fast laser deposition. The collisional-radiative model included over 3000 levels in the Ne-like through H-like ion stages of argon. The results are in agreement with highly resolved F-like to He-like K-shell emission spectra recorded recently during ultrashort laser experiments with argon cluster targets in Japan. The calculated time scale for emission is consistent with estimates of cluster decay times for these conditions. The calculations also show that the typical Li-like and Be-like satellite structure, sometimes attributed to a hot-electron component in the EEDF, can also be due to transient effects in a high-temperature ionizing plasma.