OPTICAL SPECTROSCOPY OF HIGH-L N=10 RYDBERG STATES OF NITROGEN

A Doppler-tuned CO2 laser was used to excite n=10 to n=27 Rydberg-Rydb erg transitions in a fast beam of atomic nitrogen. The fine structure of n=10, L=3-8 Rydberg levels is partially resolved in the spectrum, g iving experimental information about nitrogen Rydberg levels with L>4. The observed fine structure is well described by an effective potenti al whose empirical coefficients are adjusted to fit the data, giving e stimates of the quadrupole moment and dipole polarizabilities of N+. F or the highest-L n=27 levels studied, the spectrum shows evidence of a transition to a new coupling regime where the N+ hyperfine structure is larger than the Rydberg fine structure.