Eur. Phys. J. D 49, 173-184 (2008)
https://doi.org/10.1140/epjd/e2008-00159-2

Excitation-autoionization cross sections and rate coefficients for Ga-like ions

¹ Jerusalem College of Engineering, Ramat Beth Hakerem, 91035 Jerusalem, Israel
² Racah Institute of Physics, The Hebrew University, 91904 Jerusalem, Israel

Corresponding author: ^a pinchasm@jce.ac.il

Received: 18 November 2007
Revised: 7 May 2008
Published online: 8 August 2008

Abstract

Detailed level-by-level calculations of cross sections and rate coefficients for electron impact direct and indirect ionization of ions belonging to the GaI isoelectronic sequence (ground ) have been performed. The cross sections are presented in the energy range near the threshold for the five ions Kr⁵⁺, Mo¹¹⁺, Xe²³⁺, Pr²⁸⁺ and Dy³⁵⁺. The rate coefficients are given for ions from Kr⁵⁺ to U⁶¹⁺ in the GaI sequence at seven electron temperatures ( and , where E_I is the first ionization energy). The calculations include the contribution of direct ionization ({DI}) calculated using the Lotz formula approximation and the contributions of excitation-autoionization (EA) computed in the framework of the distorted wave (DW) approximation for the 4s–nl, 3d–nl and 3p–nl resonant inner-shell excitations. The ionization enhancement due to the EA channels is presented as a function of Z along the GaI isoelectronic sequence. The present results show the great importance of the EA processes; an ionization enhancement factor of up to 10 is predicted for instance for La²⁶⁺ (Z = 57) at electron temperature of coronal equilibrium maximum abundance.