Laser-stimulated recombination spectroscopy in highly-charged Rydberg ions

The high-angular-momentum Rydberg state structure of berylliumlike N3+ has been measured using laser-stimulated two-step recombination spectroscopy. A 65 MeV beam of N4+ ions from the MPI tandem accelerator is stored in the heavy-ion storage ring TSR and is velocity-matched with a colinear electron beam in the electron cooler section of the ring. Intense pulsed lasers stimulate selective electron capture into a high Rydberg state, followed by de-excitation to a specific lower Rydberg level. Results will be reported for weakly-perturbed high angular momentum components of the n=13-8 and n=13-7 transitions in N3+. Comparisons will be presented with previous measurements of low-n Rydberg transitions, with polarization model predictions, and with atomic structure calculations. The extension of the measurements to strongly-perturbed angular momentum states will be discussed