ELECTRON–ION COLLISIONAL IONIZATION CROSS SECTIONS FOR THE Li ISOELECTRONIC SEQUENCE

Abstract

In this work, we calculate the electron impact ionization cross sections for Li-like isoelectronicsequence ions in the range 6 £ Z £ 29 by means of a distorted-wave Born exchange approximation method including a relativistic correction. The total cross sections include the contributions from direct ionization and excitation autoionization. For excitation autoionization the branching ratio and the configuration interaction are considered. A package of computer codes has been developed and used to calculate these cross sections. Systematic study of the dependence of the cross sections on impact energies and nuclear charges is carried out. The results of the calculations are fitted by empirical formulas to meet the requirements of applications. The fitted values are in good agreement with the calculated results. ᭧

ELECTRON-ION COLLISIONAL IONIZATION CROSS SECTIONS AND RATES FOR THE Na ISOELECTRONIC SEQUENCE

“…The variations of the direct ionization cross sections with impact energy and nuclear charge are studied systematically, and empirical formulas with eight parameters are used to fit the calculated results for individual subshell ionization of the Na-like ions. This approach had been applied successfully in our earlier works to obtain the ionization cross sections for the H-, He-, Li-, and Ne-like isoelectronic sequences [14][15][16]. We also present an empirical formula able to fit the total excitation-autoionization cross sections for individual ions with high accuracy.…”

“…As in our previous papers [14][15][16], we fit the variation of the direct ionization cross sections with incident energy for ionization out of a given subshell to the following formula given by Younger [3]:…”

Electron-impact single ionization of Kr10+and Kr11+ions

“…The excitation cross section is calculated for incident electron energies from above the threshold to 3000 eV. In order to extend the calculations to still higher electron energies, the formula of Chen et al (1996) is employed to fit the excitation cross section:…”

ELECTRON–ION COLLISIONAL IONIZATION CROSS SECTIONS AND RATES FOR THE Ne ISOELECTRONIC SEQUENCE

“…The variations of the cross sections with impact energy and nuclear charge are studied systematically, and some empirical formulas are used to fit the calculated results. This approach has been applied successfully in earlier works to obtain the ionization cross sections for H-like, He-like, and Li-like isoelectronic sequences [8,9]. We have also developed an empirical formula for obtaining the ionization rates quickly and accurately [10].…”