Specific mass shift measurements in rubidium by Doppler-free two-photon transitions

We measured the isotope shifts between Rb isotopes (86m, 86g, 81) and 87Rb for the 5S1/2 to 5D5/2 transition using the Doppler-free two-photon transition technique. By making a King plot, the difference between the specific mass shift constants of the 5S1/2 and 5D5/2 states is deduced to be 77(33) GHz amu. In addition, we measured the hyperfine constants of the 5D5/2 states in those three Rb isotopes, and we have determined an improved ground state hyperfine constant in 86mRb, A(5S1/2) = 563.04(5) MHz.