It is shown that precision lifetime measurements now available for the ns-np resonance transitions in alkali-metal-like atoms and ions and the existence of strong cancellation effects in ns-${\mathit{n}}^{\prime }$p transitions for ${\mathit{n}}^{\prime }$≳n can be combined and used to specify the electric dipole polarizabilities ${\mathrm{\alpha }}_{\mathit{d}}$ of these systems to a precision comparable to that of the lifetime measurements. The method is described and applied to ${\mathrm{Mg}}^{+}$ and ${\mathrm{Ca}}^{+}$ ions. Existing precision lifetime measurements are coupled with Coulomb approximation with Hartree-Slater core calculations, which estimate the contribution of the ${\mathit{n}}^{\prime }$≳n transitions in near cancellation, and the analysis yields to values ${\mathrm{\alpha }}_{\mathit{d}}$(${\mathrm{Mg}}^{+}$)=(34.62±0.26)${\mathit{a}}_0^3$ and ${\mathrm{\alpha }}_{\mathit{d}}$(${\mathrm{Ca}}^{+}$)=(70.89±0.15)${\mathit{a}}_0^3$.

• Received 26 January 1995

DOI:https://doi.org/10.1103/PhysRevA.52.3677