Speaker
Description
Time-dependent response of strong-field driven multi-electron correlated photorecombination process is investigated by employing the perturbed trajectory measurement method. It is well-known that field-free xenon has a very large photoionization cross section around the photon energy of 80 eV as giant plasmonic resonance due to the electron-electron interaction between 4d and 5p orbitals. However, the time-dependent response of a xenon atom interacting with a strong laser field has not been investigated in attosecond time scale. Therefore, we perform the all-optical measurement of the strong-field photorecombination associated with xenon giant plasmon resonance and verify a large shift of recollisional emission time compared with the ordinary atto-chirp.
We carry out numerical simulations using time-dependent density functional theory that reproduce the large deviation of recollision emission, resulting in an attosecond pulse influenced by the giant plasmon resonance of xenon. The model we use for an atom with many electrons is a superposition of metallic shells since xenon has 54 electrons with a huge volume. The attosecond pulse calculated with the modeled atom shows characteristic features of the measured dipole radiation, making in good agreement.
We also confirm that the maximum photon energy of the attosecond pulse can exceed the cut-off estimated by the conventional theory based on the single active electron approximation. For this purpose, we calibrate the laser intensity via the cut-off photon energy of argon. Then, using the same argon-calibrated conditions, we realize that the maximum recollision energy goes over the theoretical limit, sometimes substantially, implying that the ion plays a role. We must include the plasmon’s Stark shift and whatever else might shift the resonance.
We expect that the strong-field physics associated with core electrons will modify the response of atoms and molecules on sub-cycle time scale. Eventually, it will allow us to gain optical access to control core hole dynamics.
| Keyword-1 | Ultrafast Core Hole Dynamics |
|---|---|
| Keyword-2 | Attosecond Science |
| Keyword-3 | Strong-field Physics |