Determination of dipole and quadrupole polarizabilities ofMg+by fine-structure measurements in high-Ln=17Rydberg states of magnesium

Fine-structure intervals between $n=17$ Rydberg states of magnesium with $6\le L\ge 11$ were measured using the resonant excitation Stark ionization spectroscopy technique. Comparing the measured intervals with the long-range polarization model determines the dipole and quadrupole polarizabilities of ${\text{Mg}}^{+}$ to be ${\alpha }_1=35.00\left(5\right)a_0^3$ and ${\alpha }_2=222\left(54\right)a_0^5$, respectively.