Transverse electron momentum distribution in tunneling and over the barrier ionization by laser pulses with varying ellipticity

Abstract

We study transverse electron momentum distribution in strong field atomic ionization driven by laser pulses with varying ellipticity. We show, both experimentally and theoretically, that the transverse electron momentum distribution in the tunneling and over the barrier ionization regimes evolves in a qualitatively different way when the ellipticity parameter describing polarization state of the driving laser pulse increases.

Metastable noble gas atoms in strong-field ionization experiments

“…As the polarization of the ionizing radiation becomes more circular, the peak of the distribution flattens and becomes more Gaussian. This indicates a stronger predisposition towards generating electrons with nonzero transverse momenta if the laser is circularly polarized com- [114] . TEMD of Ne * for (a) ε = 0, (b) ε = 0.42 and (c) ε = 1, respectively.…”

“…By now considering the definition for V ( p ⊥ ), it is clear to see that this can only be the case where α = 2, and hence it would be expected that as the TEMD becomes more Gaussian, α → 2. Under the assumption that the distribution is Gaussian, the Gaussian width is given by [114] σ = 1/ √ −A. By fitting Equation (52) to both the experimental and theoretical Ar and Ne * data at varying polarization ellipticities, values for α are obtained.…”

“…The intensity at which this experiment is performed is (4.8 ± 2.4) × 10 14 W cm −2 . [114] . TEMD of Ar for (a) ε = 0, (b) ε = 0.42 and (c) ε = 1, respectively.…”

“…The theoretical distributions were calculated using an iterative matrix method [114,122] to solve the time-dependent Schrödinger equation of the form…”

The interaction of excited atoms and few-cycle laser pulses

“… 20 and investigates different ionisation regimes. Recent experiments conducted by the authors demonstrate significant differences in the transverse electron momentum distribution for the OBI regime compared to the tunnelling regime 21 .…”