Professor Anatoli Kheifets
Atomic and Molecular Physics Laboratories
The process of non-sequential single-photon double ionization, and a closely related process of double ionization by a fast charged particle impact, both involve single interaction of the projectile with a target which results in simultaneous change of quantum states of two or more target electrons. These are fundamentally important processes as they constitute a direct probe of many-electron correlation, either in the initial bound state or the final multiply ionized state. The bound state correlation is a static process which can be described relatively easily by various configuration-interaction schemes. Dynamical correlation in the multi-particle continuum is much more difficult to describe theoretically. Due to a long range of the Coulomb interaction, the continuum correlation cannot be treated perturbatively and a non-perturbative approach has to be taken.
A two-particle continuum state can be treated very efficiently by the convergent close-coupling (CCC) method in which one of the particles is represented by a complete set of discrete (positive and negative energy) Laguerre basis pseudostates while the second particle is treated as a true continuum state. Details of the CCC method and its application to correlated multiple ionization processes will be presented.
I. Bray, D. V. Fursa, A. S. Kadyrov, A. T. Stelbovics and A. S. Kheifets
Electron- and photon-impact atomic ionization
Physics Reports 520, 135 (2012)