MEASUREMENT OF THE FINE-STRUCTURE SPLITTINGS OF ATOMIC SE AND SN IN THEIR GROUND P-3 STATES

Magnetic dipole transitions between the fine structure components of atomic Se and Sn in their ground P-3 states have been observed by the technique of carbon monoxide laser magnetic resonance. The fine structure intervals have been measured much more accurately than previously. For Se, the P-3(1)-P-3(2) transition was detected. Measurements were made for Se-77 through the nuclear hyperfine splitting (I = 1/2) and for Se-78 and Se-80 by the observation of Lamb (saturation) dips. The J = 1-2 interval was measured as 1989.498 12(75), 1989.497 98(36) and 1989.498 31(36) cm(-1) for Se-77, Se-78 and Se-80 respectively. The (SeSe)-Se-80-Se-78 isotopic shift has been measured very accurately from saturation dips. The gJ-factor for the P-3(2) component was estimated to be 1.491 29(14) from Zeeman splittings. The parameters which describe the hyperfine splitting for Se-77, were determined to be A(1) = -137(88) MHz and A(2) = 544(45) MHz. For Sn, both J = 1 <-- 0 and 2 <-- 1 transitions were detected. Hyperfine structure was observed, but not resolved, for Sn-117 and Sn-119, both of which have I = 1/2. The J = 1-0 interval was measured to be 1691.807 65(75) and 1691.807 10(75) cm(-1) for the unresolved pairs Sn-117/119 and Sn-118/120 respectively. The J = 2 -1 interval for the unresolved pair Sn-118/120 was determined to be 1735.864 05(75) cm(-1).