Excited-state-resolved coherent dynamics in intense SASE FEL pulses

The nonlinear interaction of intense XUV FEL pulses with atoms and molecules enables the excited-state-specific control of localized (bound) electron dynamics. Since the strongly driven bound–bound transitions are typically embedded in the ionization continuum, new effects arise such as the FEL-control of autoionizing Fano line shapes [1] and AC Stark shifts of FEL-dressed ion multiplets [2]. Hereby the specific nature of the short-lived excited state is decisive, e.g., for the control of the emission direction of the eventually ionized electron leaving the system [3]. In this talk I will review these recent activities and especially focus on new results for the coherent control of the electron emission direction in helium with two-color SASE FEL pulses. Benchmarking the state-resolved FEL-driven dynamics in relatively small and isolated atomic systems is a key ingredient for the state-specific all-XUV measurement and control of ultrafast molecular dynamics [4–7].

References:

[1] C. Ott et al., Phys. Rev. Lett. 123, 163201 (2019).

[2] T. Ding et al., Phys. Rev. Lett. 123, 103001 (2019).

[3] M. Straub et al., Phys. Rev. Lett. 129, 183204 (2022).

[4] T. Ding et al., Faraday Discuss. 228, 519–536 (2021).

[5] M. Rebholz et al., Phys. Rev. X 11, 031001 (2021).

[6] M. Rebholz et al., J. Phys. Chem. A 125, 10138–10143 (2021).

[7] A. Magunia et al., Sci. Adv. 9, eadk1482 (2023).