S. R. Lundeen

Fine Structure in High-L Rydberg States: A Path to Properties of Positive Ions

Rydberg states of atoms, molecules, and ions with large values of orbital angular momentum ( L ≥ 4 ) represent a unique class of excited states with properties quite different from lower- L Rydberg states. Because special techniques, both experimental and theoretical, are required to study them effectively, they are still relatively unexplored. As experimental knowledge and theoretical understanding of these states improves, they represent an important source of information about the positive ions that form their cores. This note will describe the special experimental and theoretical techniques that have been developed to study these states, review the progress made to date, and discuss some of the remaining challenges.

Ion properties from high-L Rydberg fine structure: dipole polarizability of Si2+

Fine structure intervals connecting n = 19 Rydberg levels of Si+ with L between 9 and 16 were measured precisely using the RESIS/microwave technique. The fine structure pattern conforms closely with that predicted by an effective potential model, and indicates a value of 11.666(4)a30 for the adiabatic dipole polarizability of the Mg-like ion, Si2+.