Reservoir spectroscopy of 5s5p 3P2-5snd 3D1,2,3 transitions in strontium

We perform spectroscopy on the optical dipole transitions 5s5p3P2-5snd3D1,2,3, n∈(5,6), for all stable isotopes of atomic strontium. We develop a spectroscopy scheme in which atoms in the metastable 3P2 state are stored in a reservoir before being probed. The method presented here increases the attained precision and accuracy by two orders of magnitude compared to similar experiments performed in a magneto-optical trap or discharge. We show how the state distribution and velocity spread of atoms in the reservoir can be tailored to increase the spectroscopy performance. The absolute transition frequencies are measured with an accuracy of 5 MHz. The isotope shifts are given to within 200 kHz. We calculate the A and Q parameters for the hyperfine structure of the fermionic isotope at the MHz level. Furthermore, we investigate the branching ratios of the 3DJ states into the 3PJ states and discuss immediate implications on schemes of optical pumping and fluorescence detection.