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Nonlinear dynamics of laser induced multiple ionization

Focus

It is now commonly accepted that the mechanism which regulate correlated emission of two electrons in atomic or molecular systems subjected to strong and short linearly polarized laser pulses follows the recollision (or three step scenario): First one electron is ionized by the field, then by reversal of the field direction it is hurled back to the core to finally collide with the remaining electron and trigger the correlated emission of the two electrons (also referred as nonsequential double ionization - NSDI). Previous studies have revealed that the dynamics of the pre-ionized electron is accurately described by a reduced model of an electron only driven by the laser. Here, we show that this picture has to be complemented by the dynamics of the other electron which is subjected to a competition between the Coulomb attraction from the nucleus and the excitation of the laser field. When combined together, these two reduced models enable to give quantitative predictions on the double ionization yield as a function of the laser intensity, a commonly investigated experimental datum.

Associated publications

Strong field double ionization of H2: Insights from nonlinear dynamics

posted May 14, 2016, 12:30 PM by François Mauger   [ updated May 14, 2016, 12:31 PM ]

Abstract

The uncorrelated (‘‘sequential”) and correlated (‘‘nonsequential”) double ionization of the H2 molecule in strong laser pulses is investigated using tools of nonlinear dynamics. We focus on the phase-space dynamics of this system, specifically by finding the dynamical structures that regulate these ionization processes. The emerging picture complements the recollision scenario by clarifying the distinct roles played by the recolliding and core electrons. Our analysis leads to verifiable predictions of the intensities where qualitative changes in ionization occur. We also show how these findings depend on the internuclear distance.

Reference

F. Mauger, C. Chandre, and T. Uzer - Strong field double ionization of H2: Insights from nonlinear dynamics - Chemical Physics 64, 366 (2009)

Strong field double ionization: what is under the ‘knee’?

posted May 14, 2016, 12:23 PM by François Mauger   [ updated May 14, 2016, 12:24 PM ]

Abstract

Both uncorrelated (‘sequential’) and correlated (‘nonsequential’) processes contribute to the double ionization of the helium atom in strong laser pulses. The double ionization probability has a characteristic ‘knee’ shape as a function of the intensity of the pulse. We investigate the phase-space dynamics of this system, specifically by finding the dynamical structures that regulate the ionization processes. The emerging picture complements the recollision scenario by clarifying the distinct roles played by the recolliding and core electrons. Our analysis leads to verifiable predictions of the intensities where qualitative changes in ionization occur, leading to the hallmark ‘knee’ shape.

Reference

F. Mauger, C. Chandre, and T. Uzer - Strong field double ionization: what is under the ‘knee’? - Journal of Physics B: Atomic, Molecular and Optical Physics 42, 165602 (2009)

Strong Field Double Ionization: The Phase Space Perspective

posted May 14, 2016, 12:18 PM by François Mauger   [ updated May 14, 2016, 12:18 PM ]

Abstract

We identify the phase-space structures that regulate atomic double ionization in strong ultrashort laser pulses. The emerging dynamical picture complements the recollision scenario by clarifying the distinct roles played by the recolliding and core electrons, and leads to verifiable predictions on the characteristic features of the ‘‘knee’’, a hallmark of the nonsequential process.

Reference

F. Mauger, C. Chandre, and T. Uzer - Strong Field Double Ionization: The Phase Space Perspective - Physical Review Letters 102, 173002 (2009)

Outreach

  • selected in the Virtual Journal of Ultrafast Science, Volume 8, issue 6 (2009)

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