Indirect spin-orbit K splittings in strontium

We use delayed field ionization to observe the microwave resonance transitions of Sr from 5snf to 5sng, 5snh, and 5sni. The energies of the 5sn center dot, center dot>3 states are split by the indirect spin-orbit coupling of the Sr core to the Rydberg electron, producing the K splittings. From the K splittings we extract the ionic dipole and quadrupole matrix elements, < 5s parallel to r parallel to 5p >=3.65(25)a(0) and < 5s parallel to r(2)parallel to 4d >=12(14)a(0)(2). From the dipole matrix element we obtain the dipole polarizability of Sr+. With the dipole polarizability and the quantum defect differences of adjacent l states, we can determine the Sr+ quadrupole polarizability. The dipole and quadrupole polarizabilities of Sr+ are alpha(d)=86(11)a(0)(3) and alpha(q)=1.1x10(3)(10)a(0)(5), respectively.