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Recollision seen by an area-preserving map

Focus

The recollision process in atomic or molecular systems subjected to strong and short linearly polarized laser pulses is the keystone process in attosecond science. This recollision follows from the three step model where a pre-ionized electron (the outer electron) is driven back to the core, by the laser, to collide with another electron still bound to the core. This recollision is a nonlinear and complex phenomenon which may result, for instance, in the emission of two correlated electrons. Here we focus on the dynamics of recollision. We show that, because of its fast motion, the outer electron can be somehow removed from the system: The bound electron is subjected to a kick by the outer electron which may result in its ionization if the kick intensity is large enough. As a test for our model, we derive a discrete time area-preserving map (see picture) which captures the bare essentials of the recollision process and enables theoretical predictions on the double ionization yields, a commonly experimentally measured data.

Associated publications

Dynamics of recollisions for the double ionization of atoms in intense laser fields

posted May 14, 2016, 12:09 PM by François Mauger   [ updated May 14, 2016, 12:10 PM ]

Abstract

We investigate the dynamics of electron-electron recollisions in the double ionization of atoms in strong laser fields. The statistics of recollisions can be reformulated in terms of an area-preserving map from the observation that the outer electron is driven by the laser field to kick the remaining core electron periodically. The phase portraits of this map reveal the dynamics of these recollisions in terms of their probability and efficiency.

Reference

F. Mauger, C. Chandre, and T. Uzer - Dynamics of recollisions for the double ionization of atoms in intense laser fields - Physical Review A 81, 063425 (2010)

From Recollisions to the Knee: A Road Map for Double Ionization in Intense Laser Fields

posted May 14, 2016, 12:06 PM by François Mauger   [ updated May 14, 2016, 12:06 PM ]

Abstract

We examine the nature and statistical properties of electron-electron collisions in the recollision process in a strong laser field. The separation of the double ionization yield into sequential and nonsequential components leads to a bell-shaped curve for the nonsequential probability and a monotonically rising one for the sequential process. We identify key features of the nonsequential process and connect our findings in a simplified model which reproduces the knee shape for the probability of double ionization with laser intensity and associated trends.

Reference

F. Mauger, C. Chandre, and T. Uzer - From Recollisions to the Knee: A Road Map for Double Ionization in Intense Laser Fields - Physical Review Letters 104, 043005 (2010)

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