Dissertation / PhD Thesis

PUBDB-2024-06572

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Controlling two-electron systems in their excited state by an intense laser field: Strong-field ionization of atomic helium & Wave-packet manipulation in molecular hydrogen

Borisova, G. (Corresponding author)Extern* ; Pfeifer, T. (Thesis advisor)Extern* ; Jochim, S. (Thesis advisor)

2024
Heidelberg University Library

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Please use a persistent id in citations: urn:nbn:de:bsz:16-heidok-343425  doi:10.11588/HEIDOK.00034342

Abstract: In this work fundamental light–matter interaction is studied in excited-state two-electron systems under the influence of an intense laser field in two respects: First, motivated by the results of a numerical simulation on the role of initial-state electron correlation for the ionization process, strong-field ionization out of selectively prepared doubly excited states (DESs) in helium is studied in a two-colour extreme ultraviolet (XUV)–infrared (IR) experiment using a reaction microscope (REMI). Detected recoil-ion and photoelectron momentum distributions help to identify a variety of different IR-induced ionization pathways for both single and double ionization out of different DESs as the initial state for strong-field interaction. Turning the focus from the atomic to the molecular two-electron system, in the second study, a novel all-optical approach enables visualisation of the dynamics of a vibrational wave packet in an electronically excited state of neutral H_2 through molecular self-probing by the ground state encoded in the reconstructed time-dependent dipole response of the excited system from XUV spectroscopy data. In a pump–control scheme, an additional interaction with a 5-fs near-infrared (NIR) pulse of adjustable intensity modifies the vibrational wave-packet revival. The adoption of an impulsive control mechanism together with state-resolved extraction of the accumulated strong-field induced phases leading to the observed revival shift brings access to state-dependent polarizability of different vibronic states in the excited wave packet. In future, both experimental approaches can be applied to multi-electron systems to study and control correlation in specifically prepared excited quantum systems.

Keyword(s): 530 Physics

Note: Dissertation, Universität Heidelberg, 2024

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)

Research Program(s):

1. 6G2 - FLASH (DESY) (POF4-6G2) (POF4-6G2)

Experiment(s):

1. FLASH2 Beamline FL26 (FLASH2)

Appears in the scientific report 2024

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