Speaker
Description
The helium atom is the ideal prototype system to investigate the role of the initial state and its electronic correlation in the ionization process with high experimental and theoretical accuracy. Here, we present an XUV-pump-IR-probe coincidence spectroscopy study of strong-field ionization from doubly excited states (DES) in helium, with a particular focus on the role of dynamic electron correlation. The doubly excited states are selectively prepared using extreme ultraviolet radiation from the free-electron laser FLASH2 and are subsequently ionized in the presence of a delayed infrared field. Using the reaction microscope of beamline FL26 we measured three-dimensional photoelectron momentum distributions of electrons emitted from the $\text{sp}_{2,3+}$ and the $3\text{s}3\text{p}$ state during single ionization. The measured distributions, benchmarked against ab initio calculations [1] incorporating electron-electron interaction in two levels of complexity – static and dynamic correlation – show that both static and dynamic correlation contribute to the observed nodal structure of the resolved differential cross sections [2].
[1] L Argenti et al, Phys. Rev. Res. 5, 033047 (2023). [2] Borisova et al., In preparation
| Scientific Topics | AMO Physics |
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