ATOMIC IRON IN ITS D-5 GROUND-STATE - A DIRECT MEASUREMENT OF THE J=0[-1 AND J=1[-2 FINE-STRUCTURE INTERVALS

The J = 0 <-- 1 and J = 1 <-- 2 fine-structure transitions in atomic F e in its ground D-5 State have been detected in the laboratory by far- infrared laser magnetic resonance. The fine-structure intervals have b een measured accurately as 2696.3942(22) and 5519.9397(18) GHz, respec tively; these values correspond to wavelengths of 111.18273 and 54.310 82 mu m, with an uncertainty of about 2 x 10(-5) mu m.