Ionization Of Helium-like Ions Research Articles

Ionization-Excitation of Helium-Like Ions at Compton Scattering

Ionization of helium-like ions with simultaneous excitation of the ns-states due to photon scattering is considered. The differential and total cross sections of the process are calculated to leading order of perturbation theory with respect to the interelectron interaction. The formulas obtained are applicable in the nonrelativistic energy range far beyond the ionization threshold.

Ionization-Excitation of helium-like ions by high-energy electrons

The differential and total cross sections are calculated for the ionization of helium-like ions that is accompanied by the excitation of residual ions to ns states owing to an electron impact. Nonrelativistic perturbation theory in electron–electron interaction with Coulomb functions used for a zero-order approximation underlies these calculations. The expressions obtained in this way have a universal character. They are applicable at moderate values of the target charge number Z and high energies of incident electrons. A comparison with total cross sections calculated for the helium atom within various theoretical approaches is performed.

Analytical evaluation of cross sections for double ionization of heliumlike ions by high-energy-photon scattering

Analytical evaluation of cross sections for double ionization of heliumlike ions by high-energy-photon scattering

Ionization of helium-like ions with excitation of nl states by high-energy photon scattering

The inelastic high-energy photon scattering on helium-like ions in the ground state, which results in ionization accompanied by simultaneous excitation of the residual ion, has been considered. Nonrelativistic perturbation theory is employed as a method. The cross sections of the process for transitions into the ns and np states are deduced in the analytical form. A comparison of our results with those of approximated calculations is given.

Electron correlations in cross sections for ionization of heliumlike ions by high-energy particle impact

We have evaluated the dominant contribution of the electron correlations to the single $K$-shell ionization cross section of heliumlike atomic systems by impact of high-energy electrons. This study is performed consistently within the framework of nonrelativistic perturbation theory. The results obtained are also applicable for the case of high-energy collisions with arbitrary charged particles whose mass is much less than that of the target. The formula for cross section is represented in the form of a universal scaling. A comparison of our numerical calculations with available experimental data is made.

Double K-shell ionization of atoms by a single photon

We investigate the double K-shell ionization of heliumlike ions by a single photon. A fast convergence of QED perturbation theory with respect to the parameter 1/Z is demonstrated in the entire nonrelativistic domain for moderate nuclear charge numbers Z≥2. The ratio of double-to-single photoionization cross sections is calculated for light heliumlike ions, taking into account the leading orders of 1/Z and αZ expansions. A comparison of our results with the available experimental data for a number of neutral atoms is presented.

Asymptotic behaviour of thetotal cross section for doubleionization of helium-like ions by electrons

The total cross sections (TCS) for double ionization ofhelium-like ions by electrons are obtained at high incident energy. For thefirst time, the leading term and the following term of the asymptoticexpression of the TCS are calculated for two-electron atomic systemsfrom He(Z = 2) to N5+(Z = 7). The obtained values ofTCS are inperfect agreement with the numerically calculated ones in the asymptoticregion. For helium the discrepancy between the theory and some ofexisting experimental data is revealed at high energies.