Role of high ponderomotive energy in laser-induced nonsequential double ionization

Abstract

The laser-induced nonsequential double ionization (NSDI) of rare gas atoms in the near and mid-IR laser fields is studied experimentally and theoretically. We investigate electron-electron correlation at high recollision energies, experimentally achieving ponderomotive energies (U p) above 80 eV. The contribution of the two dominant channels of NSDI in the photoelectron momentum distribution, impact, and excitation ionization, are both shown to scale with ponderomotive energy and are well reproduced by theory. Surprisingly, for a large U p in mid-IR fields, a noticeable electron-electron anticorrelation signal emerges at low photoelectron momenta, which cannot be explained by these mechanisms within state-of-the-art theoretical approaches.

Laser-induced nonsequential double ionization of helium: classical model calculations

“…However, it may be a quantum mechanical effect, and further experiments were needed to confirm the existence of this interesting phenomenon. We note that our CEA-DE results are strongly supported by the recent measurements of Shaaran et al [37]. The correlated momentum distribution obtained by the authors for DI of argon by 25 fs, 800 nm laser pulses of intensity of 1.5 × 10 14 W cm −2 (see figure 1(a) of reference [37]) is very similar to the distribution calculated in the CEA-DE model.…”

Pulse length effects in long wavelength driven non-sequential double ionization

“…With the help of CTMC, we can clearly understand the underlying dynamics. However, previous works [29,30] did not consider the influence of the pulse duration. In figures 3(a)-(c), we show that the PMDs have clear differences under different pulse durations and the results are consistent with the experimental results (see figure 2).…”

“…In this work, in contrast to the previous investigation [30], we focus on the dependence on the pulse-duration evolution of the PMDs in Ar driven by a 3100 nm laser field with a fixed laser intensity of about 8.0 × 10 13 W cm −2 . Such a relatively high intensity can help us to suppress the RESI mechanism and make the direct (e, 2e) NSDI the dominant path.…”

“…The mechanism behind the V-shaped structure in the long wavelength case can be extracted through a classical trajectory Monte Carlo (CTMC) model, in which the multi-return rescattering and the asymmetric energy distribution are important [29]. The investigation of NSDI under mid-IR laser fields can help us to better disentangle both different ionization mechanisms [30] and strong-field non-dipole effects [31]. Upon now, we have understood the main mechanisms of NSDI under mid-IR laser fields, however, how will the PMD evolve when the mid-IR laser field changes its parameters, such as the pulse duration, remains still unexplored.…”

The Coulomb effect in nonsequential double ionization by counter-rotating two-color elliptical polarization fields

“…[2][3][4][5] If the returning energy is large enough, after recollision both electrons are immediately released, which is the recollision-induced direct ionization (RII) mechanism. [6][7][8][9][10] If the returning energy is small, after recollision one or two electrons are excited and released with an apparent time delay. It is referred to as recollision-induced excitation with subsequent ionization (RESI).…”