Mechanism of delayed double ionization in a strong laser field

Phys Rev Lett. 2012 Feb 10;108(6):063001. doi: 10.1103/PhysRevLett.108.063001. Epub 2012 Feb 7.

Abstract

When intense laser pulses release electrons nonsequentially, the time delay between the last recollision and the subsequent ionization may last longer than what is expected from a direct impact scenario [recollision excitation with subsequent ionization (RESI)]. We show that the resulting delayed ionization stems from the inner electron being promoted to a sticky region. We identify the mechanism that traps and releases the electron from this region. As a signature of this mechanism, we predict oscillations in the ratio of RESI to double ionization yields versus laser intensity.