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.

Interaction of free electrons with electromagnetic radiation

Abstract: A study is made of the interaction of a random field of electromagnetic radiation with the free electrons of a plasma, with applications to astrophysical problems, in particular the theory of how thermodynamic equilibrium of the radiation in a hot universe is established. A kinetic equation describes the variation of the spectrum; special attention is devoted to induced scattering and the classical interpretation of induced energy and momentum transfer. In the spectra of radio sources with a high luminosity temperature, induced scattering can lead to a Bose condensation of photons, a shock wave and solitons. The scattering of strong low-frequency waves is considered in connection with their effect on pulsars and laboratory coherent generators.

Two-dimensional space-charge-limited emission: beam-edge characteristics and applications.

Abstract: There is, at present, no analytic solution that extends Child-Langmuir space-charge-limited emission beyond 1D. Herein, we investigate the characteristics of planar diode electron emission in 2D space with the emphasis on the transition region between the beam and vacuum. Current density above that predicted by Child-Langmuir is observed near the beam edges in a 2D finite element, electrostatic ray-tracing code. The properties of these increased current density "wings" are examined and then discussed in terms of their applications to cathodes which have large reservoirs of free electrons.

Enhancement of optical emission from laser-induced plasmas by combined spatial and magnetic confinement

Abstract: To enhance optical emission in laser-induced breakdown spectroscopy, both a pair of permanent magnets and an aluminum hemispherical cavity (diameter: 11.1 mm) were used simultaneously to magnetically and spatially confine plasmas produced by a KrF excimer laser in air from pure metal and alloyed samples. High enhancement factors of about 22 and 24 in the emission intensity of Co and Cr lines were acquired at a laser fluence of 6.2 J/cm2 using the combined confinement, while enhancement factors of only about 11 and 12 were obtained just with a cavity. The mechanism of enhanced optical emission by combined confinement, including shock wave in the presence of a magnetic field, is discussed. The Si plasmas, however, were not influenced by the presence of magnets as Si is hard to ablate and ionize and hence has less free electrons and positive ions. Images of the laser-induced Cr and Si plasmas show the difference between pure metallic and semiconductor materials in the presence of both a cavity and magnets.

Light quasiparticles dominate electronic transport in molecular crystal field-effect transistors

Abstract: We report on an infrared spectroscopy study of mobile holes in the accumulation layer of organic fieldeffect transistors based on rubrene single crystals Our data indicate that both transport and infrared properties of these transistors at room temperature are governed by light quasiparticles in molecular orbital bands with the effective masses m ? comparable to free electron mass Furthermore, the m ? values inferred from our experiments are in agreement with those determined from band structure calculations These findings reveal no evidence for prominent polaronic effects, which is at variance with the common beliefs of polaron formation in molecular solids