Isotope Shifts and Hyperfine Structures Investigation of Doubly Excited Levels in SrI

We measured isotope shifts and hyperfine structure of visible transitions of stable strontium isotopes by means of Doppler-free saturated absorption spectroscopy. In particular, we investigated transitions between excited states where the upper level involves two excited electrons. We report hyperfine coupling constants for the levels 5p4d1D2, 5p4d3F2, 5s4d3D1, 5s6s3S1, 5s5p3P1 and, for some of the studied transitions, we separate the specific mass and volume contribution to the isotope shifts.