MEASUREMENTS OF THE 1S2S S-1(0)-1S2P P-3(1,0) TRANSITIONS IN HELIUM-LIKE NITROGEN

Using a Doppler-tuned fast ion-beam-laser technique, with co-and count erpropagating laser beams, the intercombination 1s2s S-1(0)-1s2p P-3(1 ,F), transitions in N-14(5+) and N-15(5+) have been measured to 0.7 pp m. This precision is equivalent to 20 ppm of the two-electron Lamb shi ft and is more than two orders of magnitude more precise than current relativistic and QED theoretical results at this Z. A comparison is ma de with theory for the hyperfine structure and isotope shift. Addition ally, using a single copropagating laser beam, the differences between the 2 S-1(0)-2 P-3(1,F = 1) and 2 S-1(0)-2 P-3(0) intervals in N-14(5 +) and between the 2 S-1(0)-2 P-3(1,F = 3/2) and 2 S-1(0)-2 P-3(0) int ervals in N-15(5+) have also been measured. From the former we obtain an improved result for the N-14(5+) 2 P-3(1)-2 P-3(0) fine structure. [S1050-2947(98)04801-X].