Microwave spectroscopy of high-LRydberg states of neon

Sixteen fine-structure intervals separating n=10 neon Rydberg levels with L=5, 6, 7, and 8 were measured with the precision of about ±00.2 MHz, using fast beam microwave-optical techniques. The measured fine-structure pattern is in good agreement with the predictions of an effective potential model, and this comparison leads to precise determinations of the quadrupole moment and dipole polarizabilities of the ${}_{}{}^2{}_{}{}^{}$ ${\mathit{P}}_{3/2}$ ground state of the ${\mathrm{Ne}}^{+}$ ion: Q=-0.204 03(5)${\mathrm{ea}}_0^2$, ${\mathrm{\alpha }}_{\mathit{s}}$=1.3028(13)${\mathit{a}}_0^3$, ${\mathrm{\alpha }}_{\mathit{T}}$=-0.026(5)${\mathit{a}}_0^3$. The contributions of magnetic interactions to the Rydberg fine structure lead to a determination of the ${\mathrm{Ne}}^{+}$ ion’s g value, ${\mathit{g}}_{\mathit{J}}$=1.354(21). All of these core parameters provide challenging tests of atomic structure calculations. The measurements also set a limit on the possible contributions to the fine structure due to a predicted geometric phase effect that is about an order of magnitude smaller than expected. © 1996 The American Physical Society.