PRECISE DETERMINATION OF 135Ba+ AND 137Ba+ HYPERFINE STRUCTURE

We performed an optical double resonance experiment on the ground state of 137 and 135 Ba+ ions. About 105 particles were confined in an rf quadrupole trap for many hours. Hfs state selection by pulsed laser optical pumping was followed by microwave transition, which were observed via change in the ionic fluorescence intensity. Linewidth of the order of the laser repetition frequency (1-20 Hz) and a complicated line structure were observed in the "field independent" F=1, m=0 - F=2, m=0 transitions. The statistical uncertainty of the line center was below .1 Hz. The results for the hyperfine separations, including corrections to zero magnetic and electric field, are Ɗν (137 Ba+) = 8 037 741 667.69 (.37) Hz Ɗν (135 Ba+) = 7 183 340 234.35 (.47) H