Plasma oscillations of massless Dirac electrons in a planar superlattice

The spectrum of plasma oscillations in a lateral superlattice of massless Dirac electrons has been calculated in the weak coupling approximation. The intensity of absorption of electromagnetic waves by plasmons of the superlattice at frequencies near the edges of band gaps has been found.     

Effect of longitudinal excitations on surface plasmons

The influence of a longitudinal component in surface plasma waves propagating along the boundary between a plasma and vacuum has been investigated theoretically. It is found that the inclusion of the longitudinal component significantly modifies the dispersion relation for surface plasmons. In particular, it is shown that a surface plasmon can have any frequency in the interval from zero to the bulk plasma frequency.     

Generation of a continuum and stimulated Raman scattering harmonics during scattering of electromagnetic radiation of relativistic intensity

A theory of the propagation instability of plane, monochromatic, circularly polarized electromagnetic waves of relativistic intensity in matter is developed for a spatially three-dimensional geometry including arbitrary polarization of the scattered radiation. Harmonic generation owing to striction and relativistic nonlinearity is examined, as well as scattering owing to electron recoil, the decay instability of the harmonics with formation of scattered electromagnetic waves (Stokes components of the stimulated Raman scattering and plasmons), the interaction of electromagnetic waves in the plasma (antistokes stimulated Raman scattering), and the generation of a radiative continuum. The transition of the three-dimensional theory to a one-dimensional problem in the nonrelativistic limit is discussed. Zh. éksp. Teor. Fiz. 113, 2034–2046 (June 1998)     

New branch of intersubband plasmons in a nonequilibrium two-layer system

The plasma oscillation spectrum for 2D electrons in a double quantum well is calculated. It is shown that an additional branch of intersubband plasmons can exist without experiencing Landau damping in the case of nonequilibrium population of subbands. In an asymmetric structure, this branch is responsible for both the emergence of instabilities and the possibility of amplification of plasma waves.     

Effect of metallic surface microroughness on the probability and spectrum of plasmon excitation by a fast charged particle moving parallel to the surface

The Green’s function of the electric field of plasmons is determined in a semi-infinite medium with an abrupt plasma boundary where nonequilibrium conduction electrons either undergo elastic reflection from the boundary or “stick” to it and give rise to a stationary surface charge. The angular reflection of elastically scattered electrons can be either specular or diffuse. The Green’s function is used to find the singleevent spectrum of energy loss by a fast electron moving parallel to the boundary. The effect of electronboundary scattering parameters on the structure of bulk and surface plasmon resonances is analyzed. The probability of transition radiation of bulk plasmon by an electron moving in vacuum is examined. A new type of surface resonance is found under conditions of perfectly elastic scattering of conduction electrons from the plasma boundary, similar in structure to a tangential surface plasmon.     

Solitary Waves in Relativistic Electromagnetic Plasma

Solitary waves in relativistic electromagnetic plasmas are obtained numerically. The longitudinal momentum of electrons has been taken into account in the problem. It is found that in the moving frame with electromagnetic field propagating the solitary waves can exist in both cases, where the vector potential frequency is larger or smaller than the plasma characteristic frequency.     

损耗对表面等离子体激元压缩态的影响

表面等离子体激元是金属表面电子集体振荡,它以波的形式在金属和介质之间的界面中传播.近期Huck等证明等离子体激元可以处在压缩态,本文利用量子光学的热库理论,研究金波导损耗对表面等离子体激元压缩态的影响,并对Huck等的实验结果给与理论解释. 关键词： 表面等离子体激元 压缩态 热库理论     

Trinal Nature of the Excitation of Bulk Plasmons by a Fast Charged Particle at Grazing Incidence on the Interface between Vacuum and a Metal with Strong Spatial Dispersion

The excitation and propagation of bulk and surface (surface waves of transition radiation of plasmons at frequencies above the plasma frequency) plasma waves by incident electrons moving both in vacuum toward the surface of a metal and inside the metal whose boundary elastically and spectacularly reflects internal nonequilibrium electrons have been analyzed. In contrast to work [B. N. Libenson, J. Exp. Theor. Phys. 113, 553 (2011)], attention in this work is focused on the influence of surface effects on bulk-plasmon excitation by incident electrons. The probabilities and spectra of single characteristic energy loss of an intermediate- energy electron (50–500 eV) moving at an angle to the surface of the medium in three regions: in vacuum, in the medium, and again in vacuum after the electron leaves the medium are calculated. The kinetic approximation is used for the dielectric function, where the entire range of the plasmon spectrum is taken into account correctly for the problem under consideration. In the indicated energy range of incident electrons, surface effects, on the one hand, significantly reduces the probability of excitation of bulk plasma waves in the medium with strong spatial dispersion, in particular, as compared to the results obtained in [B.N. Libenson, J. Exp. Theor. Phys. 113, 553 (2011)], where surface effects were disregarded and the probability of bulkplasmon excitation by a 200-eV electron incident and emitted perpendicularly to the boundary is about one third of that in the unbounded medium. On the other hand, at grazing incidence from vacuum, the probability of transition radiation of bulk plasmons increases significantly and can lead to a change in the character of the angular dependence of the intensity of bulk plasma energy loss. Thus, the main result of this work is that a decrease in the glancing angle of the fast electron with respect to the vacuum–metal interface is accompanied both by an increase in the contribution from the transition mechanism to the probability of bulk-plasmon excitation in the vacuum region and by a decrease in the contribution from Cherenkov and bremsstrahlung mechanisms of excitation in the medium. The probability of bulk-plasmon excitation in the vacuum region exceeds the probability of excitation at the further motion of the electron in metallic aluminum at angles of incidence larger than 65°, 70°, and 75° at the energies E = 200, 350, and 500 eV, respectively.     

Non-relativistic quantum theory of stimulated Cherenkov radiation and Compton scattering in plasma

The stimulated processes in electron plasma, i.e., Cherenkov radiation by a nonrelativistic electron beam of longitudinal oscillations and Compton scattering of a transverse electromagnetic wave in plasma with quantum mode excitation (de Broglie wave), are considered in the three-wave approximation. The possibility of the occurrence of quantum oscillations is discussed.     

Quantum kinetic theory of confined electrons in a strong time dependent field

A gauge-invariant Green’s function approach to the quantum transport of spatially confined electrons in strong electromagnetic fields is presented. The theory includes mean field and exchange effects, as well as collisions and initial correlations. It allows for a self-consistent treatment of spectral properties and collective effects (plasmons), on one hand, and nonlinear field phenomena, such as harmonic generation and multiphoton absorption, on the other. It is equally applicable to electrons in quantum dots, ultracold ions in traps and valence electrons of metal clusters.     

Penetration of electromagnetic waves into magnetoactive plasma

Landau studied the longitudinal field penetration into a semi-bounded plasma considering specularly reflecting electrons at the boundary. Kurilko and Popov and then Gorman examined the same problem considering a fraction “p” of all incident electrons reflecting specularly and the remaining portion difusely. Lastly, Mason treated the same problem at length and gave solutions for specular and diffuse reflections. Here the penetration of transverse electromagnetic waves into magnetoactive semi-bounded plasma has been studied and the electric field for specular reflection of electrons is obtained.     

Vavilov-Cherenkov like effect in metal nanofilms

The so-called surface plasmon polaritons, i.e., natural waves with a low phase velocity (much lower than the speed of light in a vacuum), exist in silver, gold, and copper nanofilms and nanowires. Electrons that are relatively slow in comparison with those that emit Cherenkov light in a homogeneous medium produce plasmons. The dispersion relations for the corresponding plasmons and the emission angles of plasmons with corresponding frequencies are calculated. It is shown that devices based on detecting Cherenkov light in nanofilms and nanowires can be used to detect low-energy electrons.     

Plasmon mechanism of light transmission through a metal film or a plasma layer

It is shown that a smooth metal film (or a plasma layer) can be made transparent for an electromagnetic wave when two identical subwavelength diffraction gratings are placed on both sides of the film. The electromagnetic wave transmission through the metal film is caused by excitation of evanescent surface waves (plasmons) and their transformation into propagating waves at the gratings. A model which is developed analytically shows that the problem of the wave transmission is physically equivalent to the problem of excitation of two coupled resonators of evanescent waves which are formed at the two film surfaces.     

Total absorption of an electromagnetic wave by an overdense plasma

We show both theoretically and experimentally that an electromagnetic wave can be totally absorbed by an overdense plasma when a subwavelength diffraction grating is placed in front of the plasma surface. The absorption is due to dissipation of surface plasma waves (plasmons polaritons) that have been resonantly excited by the evanescent component of the diffracted electromagnetic wave. The developed theoretical model allows one to determine the conditions for the total absorption.     

A theoretical study of hot plasma spheroids in the presence of low-frequency electromagnetic waves

While taking into account thermal motion of electrons, scattering of electromagnetic waves with low frequency from hot plasma spheroids is investigated. In this theoretical research, ions are heavy to respond to electromagnetic fluctuations. The solution of scalar wave equation in spheroidal coordinates for electric potential inside the plasma spheroids are obtained. The variations of resonance frequencies vs. Debye length are studied and consistency between the obtained results in this paper and the results for the well-known plasma objects such as plasma column and spherical plasma have been proved.     

Vacuum electron acceleration by coherent dipole radiation

The validity of the concept of laser-driven vacuum acceleration has been questioned, based on an extrapolation of the well-known Lawson-Woodward theorem, which stipulates that plane electromagnetic waves cannot accelerate charged particles in vacuum. To formally demonstrate that electrons can indeed be accelerated in vacuum by focusing or diffracting electromagnetic waves, the interaction between a point charge and coherent dipole radiation is studied in detail. The corresponding four-potential exactly satisfies both Maxwell's equations and the Lorentz gauge condition everywhere, and is analytically tractable. It is found that in the far-field region, where the field distribution closely approximates that of a plane wave, we recover the Lawson-Woodward result, while net acceleration is obtained in the near-field region. The scaling of the energy gain with wave-front curvature and wave amplitude is studied systematically.