Eur. Phys. J. D (2014) 68: 2
https://doi.org/10.1140/epjd/e2013-40619-x

Regular Article

Ionization cross sections and rate coefficients for the ground state of AsI-like ions

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

^a e-mail: pinchasm@jce.ac.il

Received: 10 October 2013
Received in final form: 17 November 2013
Published online: 22 January 2014

Abstract

Detailed level-by-level calculations of cross sections and rate coefficients for electron impact direct ionization and excitation-autoionization of AsI-like ions in the 3d¹⁰4s²4p³ (⁴S_3/2) ground state have been performed. The cross sections are presented in the energy range near the threshold for the five ions Mo⁹⁺, Xe²¹⁺, Pr²⁶⁺, Dy³³⁺ and W⁴¹⁺. The rate coefficients are given for all the ions from Sr⁵⁺ to U⁵⁹⁺ in the AsI sequence at the seven electron temperatures (kT_e = 0.1E_I,0.3E_I,0.5E_I,0.7E_I,E_I,2E_I and 10E_I, 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 AsI isoelectronic sequence. The present results show the great importance of the EA processes; an ionization enhancement factor of up to 6.5 is predicted for instance for Dy³³⁺ (Z = 66) at electron temperature of coronal equilibrium maximum abundance.