Fig. 4: Avoided crossing phenomena in the energy domain.
From: Observation of Rabi dynamics with a short-wavelength free-electron laser
a, Photoelectron kinetic energies, for one photon above the energy of the dressed-atom states, as a function of detuning. b–d, Photoelectron spectra as a function of the photon energy retrieved experimentally (b), using TDCIS (c) and using the total analytical model for 3/2 Rabi periods (d). In each case, the dashed white line corresponds to the photon energy for the 1s2 → 1s4p transition in helium. The shifts between the energy scales of a and b, and the energy scales of c and d, are due to the difference between the experimental and the Hartree–Fock ionization potential. a.u., arbitrary units.
