Hyperfine structure in the 4d states of Rb-like Sr

Relativistic coupled-cluster calculations are presented for the low-lying states of the Rb-like ion Sr-87(+), of interest as a possible frequency standard. The resulting constants for the magnetic hyperfine stucture were: A(5s) = -1000 MHz, A(5p(1/2)) = -177 MHz, A(5p(3/2)) = -35 MHz, A(4d(3/2)) = -47 MHz and A (4d(5/2)) = +1 MHz. As a result of the abnormally small A factor for the 4d5/2 state, the electric and magnetic hyperfine structures are comparable for that state. Electronic factors for the electric hyperfine structure were evaluated for the states with j > 1, giving B(5P(3/2))/Q = 271 MHz b(-1), B(4d(3/2))/Q = 115 MHz b(-1) and B(4d(5/2))/Q = 160 MHz b(-1). The calculated B/Q value for the 5P(3/2) state was combined with experimental B factors for the isotope sequence Sr79-93, giving revised values for the nuclear quadrupole moments.