Charge oscillation in multiphoton and tunneling ionization of rare-gas dimers

Abstract

We perform a comparison study on strong-field ionization of the rare-gas dimers (Kr${}_{2}$ and Ar${}_{2}$) with their rare-gas monomers (Kr and Ar) in infrared laser fields at wavelengths of 795 and 1320 nm in the intensity range of (0.4--2)\ifmmode\times\else\texttimes\fi{}10${}^{14}$ W/cm${}^{2}$. The photoelectron longitudinal momentum distributions of the rare-gas dimers reveal prominent intensity and wavelength dependence. Compared to that of the rare-gas monomers, photoelectrons obtain smaller drift momentum for multiphoton ionization of the dimers at the same laser intensity. However, in the tunneling regime, the ionization of the dimers shows similar photoelectron longitudinal momentum distributions with the monomers at the same laser intensity. We identify that, for multiphoton ionization of the dimers, the recaptured electrons during rescattering prefer to start charge oscillation in the dimer ions, which is coupled by the laser field. When the laser field decreases, the charge oscillated electrons will be released and will have less chance to obtain larger drift momentum from the laser field. The ionization of the dimers in the tunneling regime behaves much like the ionization of one of the two constituent, nearly unperturbed rare-gas atoms.

Keywords

Affiliated Institutions

• Peking University CN
• Collaborative Innovation Center of Quantum Matter CN

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