TY  - JOUR
AU  - Aufleger, Lennart
AU  - Friebel, Patrick
AU  - Rupprecht, Patrick
AU  - Magunia, Alexander
AU  - Ding, Thomas
AU  - Rebholz, Marc
AU  - Hartmann, Maximilian
AU  - Ott, Christian
AU  - Pfeifer, Thomas
TI  - Line-shape broadening of an autoionizing state in helium at high XUV intensity
JO  - New journal of physics
VL  - 24
IS  - 1
SN  - 1367-2630
CY  - [London]
PB  - IOP
M1  - PUBDB-2022-01703
SP  - 013014 -
PY  - 2022
AB  - We study the interaction of intense extreme ultraviolet (XUV) light with the 2s2p doubly excitedstate in helium. In addition to previously understood energy-level and phase shifts, high XUVintensities may lead to other absorption-line-shape distortions. Here, we report on experimentaltransient-absorption spectroscopy results on the 2s2p line-width modification in helium in intensestochastic XUV fields. A few-level-model simulation is realized to investigate the origins of thiseffect. We find that the line-shape broadening is connected to the strong coupling of the groundstate to the 2s2p doubly excited state which is embedded in the ionization continuum. As thebroadening takes place for intensities lower than for other strong-coupling processes, e.g. observedasymmetry changes of the absorption profile, this signature can be identified already in anintermediate intensity regime. These findings are in general relevant for resonant inner-shelltransitions in nonlinear experiments with XUV and x-ray photon energies at high intensity.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000749506300001
DO  - DOI:10.1088/1367-2630/ac3b2e
UR  - https://bib-pubdb1.desy.de/record/476364
ER  -