Total Electron Production Research Articles

Charge Transfer and Electron Production in Proton Collisions with Uracil: A Classical and Semiclassical Study.

Cross sections for charge transfer and ionization in proton-uracil collisions are studied, for collision energies 0.05<E<2500 keV, using two computational models. At low energies, below 20 keV, the charge transfer total cross section is calculated employing a semiclassical close-coupling expansion in terms of the electronic functions of the supermolecule (H-uracil)+. At energies above 20 keV, a classical-trajectory Monte Carlo method is employed. The cross sections for charge transfer at low energies have not been previously reported and have high values of the order of 40 Å2, and, at the highest energies of the present calculation, they show good agreement with the previous results. The classical-trajectory Monte Carlo calculation provides a charge transfer and electron production cross section in reasonable agreement with the available experiments. The individual molecular orbital contributions to the total electron production and charge transfer cross sections are analyzed in terms of their energies; this permits the extension of the results to other molecular targets, provided the values of the corresponding orbital energies are known.

Measurement of absolute rates for multiphoton ionization of atomic hydrogen at 248 nm.

We present measurements of absolute rates for multiphoton ionization of the ground state of atomic hydrogen by a linearly polarized, subpicosecond KrF laser at a wavelength of 248 nm. The irradiance was varied from 3\ifmmode\times\else\texttimes\fi{}${10}^{12}$ to 2\ifmmode\times\else\texttimes\fi{}${10}^{14}$ W/${\mathrm{cm}}^{2}$, and three above-threshold-ionization peaks were observed. The measured rate for total electron production was less than that predicted by Floquet theory [S.-I. Chu and J. Cooper, Phys. Rev. A 32, 2769 (1985)] and perturbation calculations [S. V. Khristenko and S. I. Vetchinkin, Opt. Specktrosk. 40, 417 (1976)], but significantly higher than calculated by the Reiss [Phys. Rev. A 22, 1786 (1980)] and Keldysh [Sov. Phys.---JETP 20, 1307 (1965)] methods using Volkov final states.

General Properties of Highly Excited Direct Semiconductors in the Athermal Stage

AbstractStarting from first principles and prolonging a series of three previous papers some general and global properties of highly excited direct semiconductors are considered. The evolution of the lengths of the state vectors is considered and some properties are discussed. Furthermore the evolution of the total electron production rate and of the total energy are investigated. Thereby new terms are derived which describe the energy storage due to nonlinearities in the evolution equations. Finally, some aspects of ultrashort pulse duration are considered.

Angular and energy dependence of cross sections for ejection of electrons from water vapor. III. 20-150-keV neutral-hydrogen impact.

Absolute values of cross sections for electron production in collisions of neutral hydrogen atoms of 20--150 keV energy with water vapor molecules have been measured as a function of the ejection energy and angle. The range of angles was 10/sup 0/ to 160/sup 0/ and the electron energy range was 1--300 eV. The doubly differential cross sections were integrated over angle and/or energy to obtain singly differential cross sections, total electron production cross sections, and average energies of ejection. The angular distribution of the electron loss peak was found to have some features in common with the cross section for elastic scattering of electrons.

First Born approximation electron loss, ionization and total electron production cross sections for fast positive helium ions incident on atomic helium

The first Born length and velocity approximation is used to calculate cross sections for one-electron loss, total electron production and ionization occurring in the collision of fast singly ionized helium with neutral atomic helium. Account is taken of double transitions. Good agreement between the theoretical and experimental values of the one-electron loss, total electron production and ionization cross sections is found for impact energies greater than 1000 and 300 keV respectively.

On ionization in the ionospheric D-region by galactic and solar cosmic rays

Electron production rate q and electron density N produced by cosmic rays (CR) in the lower part of the D-region are theoretically considered in this paper. On the basis of the obtained formulas q and N are calculated from galactic CR for four geomagnetic latitudes 0°, 30°, 41°, 55° at maximum and minimum solar activity in winter and summer. The ionization by solar CR is considered—the so called polar cap absorption event. Solutions of q( h) are obtained in the cases of flat and spherical Earth and calculations are made for clearing up the contribution of the protons, α-particles and H-nuclei ( Z = 10) in the rate of total electron production.

Charge transfer and ionization by positive ions in the energy range 60 to 450 keV

Charge transfer and ionization by singly charged positive ions have been investigated by means of a variation of the well-known condenser method in which slow charge collection over a precisely determined path length is carried out at pressures low enough to ensure single collision conditions; a uniform axial magnetic field enables total slow ion currents to be measured. The apparent total charge transfer cross-section, the total electron production cross-section and the total slow ion production cross-section have been determined for seventeen cases involving rare gas ions in the rare gases and hydrogen.