Energy distribution of field emission electrons from carbon nanocrystals

Using a field electron microscope and a field electron dispersion energy analyzer, carbon nanocrystals contained in polyacrylonitrile (PAN) fibers are studied. Transition of the emitting nanocrystals into the second stable state has been discovered, corresponding to an emission current and field electron energy distribution of magnitudes lower by nearly an order of magnitude, with an additional low-energy peak. Heating the samples at 750° C restores the initial characteristics of the field electron energy distribution and current-voltage characteristics of the nanocrystals. The forbidden bandwidth of the nanocrystals has been determined.     

Variational calculation of the partition function of a system of electrons in a random field

A variational method is developed for calculating the partition function of a nondegenerate system of electrons in a Gaussian random field. Path integrals are used. The partition function with a model action that generalizes the one used by Feynman is calculated explicitly.Translated from IzvestiyaVysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 47–52, February, 1976.I thank V. L. Bonch-Bruevich for a helpful discussion.     

Energy partition in nuclear fission

A scission point model (two spheroid model TSM) including semi-empirical, temperature-dependent shell correction energies for deformed fragments at scission is presented. It has been used to describe the mass-asymmetry-dependent partition of the total energy release on both fragments from spontaneous and induced fission. Characteristic trends of experimental fragment energy and neutron multiplicity data as function of incidence energy in the Th — Cf region of fissioning nuclei are well reproduced. Based on model applications, information on the energy dissipated during the descent from second saddle of fission barrier to scission point have been deduced.     

Detachment of electrons from atmospheric oxygen molecules in a high electric field

The results of experiments on the electrical breakdown of air in a quasi-optical microwave beam with a deeply subcritical initial field have been reported. Breakdown has been initiated by a cylindrical vibrator with spherically rounded ends and a vibrator with a tapered end. The experimental data suggest that the amount of initial breakdown-initiating electrons in a breakdown area can be provided by the detachment of electrons from atmospheric oxygen molecules. The effect of detachment depends on the field strength.     

Rayleigh scattering of light by two-dimensional electrons in a high magnetic field

Resonance Rayleigh scattering of light by a two-dimensional electron system in the ultraquantum limit is investigated. The scattering process under study involves electronic states belonging to the two spin sublevels of the zero Landau level. It is shown that the main contribution to resonance Rayleigh scattering originates from the fluctuations of the random potential in the quantum well hosting the two-dimensional system.     

Photoemission at high quantum energies. Energy distribution of escaping electrons

Photoemission at light quantum energies exceeding the production threshold of electron-hole pairs is considered. Broadening of the energy spectrum of detectable photoelectrons associated with the instability of electron states above the pair-production threshold and the distribution of secondary electrons with respect to energies are calculated. It is shown that this distribution is determined by a single parameter under given conditions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 23–28, September, 1975.I wish to express my deep appreciation to V. L. Bonch-Bruevich for constant attention in the study.     

Enhancement of high harmonics generated by field steering of electrons in a two-color orthogonally polarized laser field

We demonstrate enhancement by 1 order of magnitude of the high-order harmonics generated in argon by combining a fundamental field at 1300 nm (10(14) W cm(-2)) and its orthogonally polarized second harmonic at 650 nm (2 × 10(13) W cm(-2)) and by controlling the relative phase between them. This extends earlier work by ensuring that the main effect is the combined field steering the electron trajectory with negligible contribution from multiphoton effects compared to the previous schemes with 800/400 nm fields. We access a broad energy range of harmonics (from 20 eV to 80 eV) at a low laser intensity (far below the ionization saturation limit) and observe deep modulation of the harmonic yield with a period of π in the relative phase. Strong field theoretical analysis reveals that this is principally due to the steering of the recolliding electron wave packet by the two-color field. Our modeling also shows that the atto chirp can be controlled, leading to production of shorter pulses.     

Energy degradation of electrons in krypton

The problem of energy degradation of electrons in krypton has been investigated using the Monte Carlo method. The results are presented as the probability distributions of the number of ionizations, the Fano factor, the mean energy per ion pair and the degradation spectra for source energies up to 4 keV.     

Energy distributions of field emitted electrons from few-layer graphene sheets with AB and ABC stacking

We study the effect of the band structure on the energy distributions of field emitted electrons from AB and ABC graphene multilayers. The characteristic sub-peaks are found to appear for each type of stacking. The experimental discovery of these peaks in field emission experiments from carbon few-layer systems can provide important information about a type of stacking.     

Bloch electrons in a magnetic field

A complete set of basis functions for the expansion of the wavefunction of a Bloch electron in a uniform magnetic field is derived. In the empty lattice limit this set gives the appropriate Landau free-electron wavefunctions, contrary to the Roth functions which in that limit are plane waves.     

Bloch electrons in constant electric field

The motion of a conduction electron of a crystal in a constant electric field is studied. It is shown that the modulus of the wave function inp-representation is well approximated by a periodic function for times smaller than several hundred periods.On leave from Department of Physics, Luminy, Université d'Aix-Marseille II, and Centre de Physique Théorique, CNRS, Marseille, France     

Energy spectrum of ejected electrons in ionization of hydrogen atoms by electrons

Energy spectrum of ejected electrons in ionization of hydrogen atoms has been calculated following a multiple scattering theory of Das and Seal [15]. The results show peaks around two to three Rydbergs of energies of the ejected electrons, for incident electron energy of 250 eV and 500 eV, considered here, and for different combinations of the angular variables of the scattered and the ejected electrons, for scattering in a plane. The peaks are very similar to those observed in relativistic K-shell ionization of Ag atoms by electrons at 500 KeV energy [6]. The physical origin of these peaks may be traced to the second order scatterings, scattering first by the atomic nucleus (or the atomic electron) and then a second time by the atomic electron. These peaks are, however, absent in the first Born results. Experimental verification of the present results and theoretical calculation by some other well-known methods will be interesting.     

Energy spectra of electrons in plasma accelerators

The acceleration of electrons in the fast (relativistic) plasma wave, generated, e.g., by intense laser pulse in an underdense plasma, is studied theoretically and numerically. The analytical method, developed to describe the energy spectrum of electrons accelerated in one-dimensional (1-D) plasma wave of an arbitrary form, predicts the “bunching” of electrons in the energy space for linear (harmonic) plasma wave in contrast to the nonlinear one. The results of one- and two-dimensional (2-D) numerical simulations of the resonant and nonresonant electron bunch acceleration are presented and discussed     

Energy spectra of electrons in a crystal

The characters are given for the irreducible nonequivalent weighted corepresentations for all possible types of coequivalent weights for groups D₂h, D_4h, and D₆h.     

Energy losses of electrons in oriented crystals

Abstract

Within the framework of the multistring model of axial channeling of electrons the method for calculating the losses to radiation in channeling is proposed. The physical model includes the multiple scattering, the beam and target characteristics. The simulated results are compared with the experimental data.