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 $A\left(S_{\frac{1}{2}}\right)=394\pm 3\text{mK}$ and $A\left(P_{\frac{1}{2}}\right)=691\pm 4\text{mK}$. The dipole moment of ¹⁹⁷Tl calculated from the ratio of hyperfine splittings is μ_I(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.