HYPERFINE-INDUCED 1S2S S-1(0)-1S2P P-3(0) TRANSITION AND FINE-STRUCTURE MEASUREMENT IN HELIUM-LIKE NITROGEN

We have observed the 1s2s S-1(0)-1s2p P-3(0) transition in N-14(5+) us ing Doppler-tuned fast-beam laser spectroscopy. This transition, absol utely forbidden for atoms with zero nuclear spin, occurs due to mixing of states of different J by the hyperfine interaction. By measuring t he difference between the 2(1)S(0)-2 P-3(1,F) and 2(1)S(0)-2 P-3(0) tr ansition energies, we have obtained a value for the 1s2p (3)p(1)-(3)p( 0) fine-structure splitting in N5+. Our result will test quantum-elect rodynamic corrections to recent high precision calculations [Z.-C. Yan and G.W.F. Drake, Phys. Rev. Lett. 74, 4791 (1995)].