Blättermann, AlexanderKaldun, AndreasStoob, V.Donsa, StefanWei, HuiPazourek, RenateNagele, StefanOtt, ChristianLin, Chii-DongBurgdörfer, JoachimPfeifer, Thomas2020-06-172020-06-172017-11-01https://hdl.handle.net/2097/40728We report on the experimental observation of the buildup of the 2s2p Fano resonance in helium in the time domain, which has been under theoretical investigation for more than a decade. The emergence of the absorption line is temporally resolved by interrupting the natural decay of the excited state via saturated strong-field ionization at a variable time delay. We compare the experimental data with full ab-initio simulations to validate the time-gating by strong-field ionization and thereby confirm the recently developed theory for the formation of Fano line-profiles.Attribution 3.0 Unported (CC BY 3.0)Creative Commons Attribution 3.0 licencehttps://publishingsupport.iopscience.iop.org/open_access/https://creativecommons.org/licenses/by/3.0/Fano resonanceDoubly Excited heliumabsorption linenatural decayText