LASER-RF DOUBLE-RESONANCE STUDY OF N2+

We have applied the laser-rf-laser double-resonance method to a molecular ion. Fifty-six hyperfine components of fine-structure transitions (DELTA-J = +/- 1) were measured in rotational levels from N = 1 to 27 of the upsilon" = 1 vibrational level of the X 2SIGMA-g+ ground electronic state of N-14(2)+. In order to fit the data, we required seven molecular constants, corresponding to the following interactions: electron spin-rotation fine structure and its centrifugal distortion, Fermi-contact hyperfine structure (hfs), dipolar hfs and its centrifugal distortion, and electric quadrupole and nuclear spin-rotation hfs. The results are in reasonable agreement with theoretical calculations based upon a Hartree-Fock-Roothaan wave function.