Measurement of the electric quadrupole moment of the 4d2D5/2 level in 88Sr+ -: art. no. 133001

The quadrupole moment of the 4d D-2(5/2) level in Sr-88(+) has been measured to be 2.6(3)ea(0)(2), where a(0) is the Bohr radius and e the elementary charge. A single laser-cooled strontium ion was confined in an end cap trap with a variable dc quadrupole potential, and measurements were made on the 5s S-2(1/2)-4d D-2(5/2) transition at 674 nm using a femtosecond optical frequency comb. This work shows that measurements of the unperturbed Sr-88(+) transition frequency with sub-Hz uncertainty are possible and is important in understanding the reproducibility of ion trap optical frequency standards.