Eur. Phys. J. D (2014) 68: 349
https://doi.org/10.1140/epjd/e2014-50614-4

Regular Article

Photoionization dynamics of the C²⁺ ion in Rydberg states^*

National Institute for Laser, Plasma and Radiation Physics, Department of Lasers, Atomistilor 409, P.O.Box MG-36, 077125 Magurele-Ilfov, Romania

^a e-mail: viorica.stancalie@inflpr.ro

Received: 21 August 2014
Received in final form: 19 September 2014
Published online: 17 November 2014

Abstract

The goal of this work is to examine in detail the ionization dynamics of Be-like C ion in Rydberg states. An initial calculation has been done to output the lifetime due to spontaneous decay for unperturbed 1s²2sns (¹S^e) Rydberg states using the multi-configuration Dirac-Fock (MCDF) method with configuration interaction option implemented in the general-purpose relativistic atomic structure package (GRASP). Both the C²⁺ ground state and the C³⁺ target state energies have been carefully calculated. We report results from a detailed and systematic study of the behaviour of complex photoionization amplitudes, the lifetime due to spontaneous decay for unperturbed 1s²2sns (¹S^e) Rydberg states, the ‘resonant’ phase shift and the rapidly increasing of this shift from well below to well above the resonance position. The sum-over-state method is used to calculate the static dipole polarizability, while the frequency-dependent polarizability values of C²⁺ ion in these Rydberg states are obtained from two-state model calculation results.