Extended Data Fig. 4: Mapping of the second excitation step.
From: Laser spectroscopic characterization of the nuclear-clock isomer 229mTh
The experimental points represent amplitudes and positions of the two-step resonances obtained by setting the 484-nm laser at certain frequencies and tuning the 1,164-nm laser. The frequency of the 484-nm laser is changed in steps of about 120 MHz. The resonance groups shown with the same colour correspond to transitions from the same intermediate state with total angular momentum F, which is populated from different ground-state hyperfine components. The graphs show the HFS transitions of 229Th2+ in the ground state (a) and the isomer (b).
