Hyperfine Structure, Nuclear Moments, and Isotope Shifts of ^197Tl and ^198Tl

The hyperfine structure of 197Tl has been derived from an analysis of two lines in the optical spectrum observed under high resolution. The magnetic dipole interaction constants are A(S12)=394±3mK and A(P12)=691±4mK. The dipole moment of 197Tl calculated from the ratio of hyperfine splittings is μI(197) = 1.55 ± 0.02 nm. The hyperfine structure of 198Tl was not resolved. Isotope shifts measured with respect to 205Tl were found to be Δ (197–205) = −234 ± 4 mK and Δ (198–205) = −229 ± 4 mK in the 5350-Å line and Δ (197–205) = −210 ± 4 mK and Δ (198–205) = −209 ± 4 mK in the 3776-Å line.