Polarizability of Rn-like Th4+from spectroscopy of high-LRydberg levels of Th3+

Abstract

Binding energies of high-$L$ Rydberg levels of Th${}^{3+}$ were measured using the resonant excitation Stark ionization spectroscopy technique. Analysis of the data with the long-range polarization model leads to determination of dipole and quadrupole polarizabilities of the free Th${}^{4+}$ ion, ${\ensuremath{\alpha}}_{\mathrm{d}}$ $=$ 7.61(6) a.u., ${\ensuremath{\alpha}}_{\mathrm{Q}}$ $=$ 47(11) a.u.