Precision Spectroscopy and Nuclear Structure Parameters in 7Li+ ion

The optical Ramsey technique is used to obtain precise measurements of the hyperfine splittings in the 2\, ³\!S₁ and 2\, ³\!PJ states of ⁷Li^+. Together with bound-state quantum electrodynamic theory, the Zemach radius and quadrupole moment of the ⁷Li nucleus are determined to be 3. 35 (1) ~fm and -3. 86 (5) ~fm² respectively, with the quadrupole moment deviating from the recommended value of -4. 00 (3) ~fm² by 1. 75. Furthermore, we determine the quadrupole moment ratio of ⁶Li to ⁷Li as 0. 101 (13), exhibiting a 6 deviation from the previous measured value of 0. 020161 (13) by LiF molecular spectroscopy. The results taken together provide a sensitive test of nuclear structure models.