LAUSR

Hyperfine structure and isotope shifts have been measured for the ground and isomeric states in the neutron-deficient isotopes Tl179-184 using the 276.9-nm transition. The experiment has been performed at the CERN-Isotope Separator On-Line facility using the in-source resonance-ionization laser spectroscopy technique. Spins for the ground states in Tl179,181,183 have been determined as I=1/2. Magnetic moments and changes in the nuclear mean-square charge radii have been deduced. By applying the additivity relation for magnetic moments of the odd-odd Tl nuclei the leading configuration assignments were confirmed. A deviation of magnetic moments for isomeric states in Tl182,184 from the trend of the heavier Tl nuclei is observed. The charge radii of the ground states of the isotopes Tl179-184 follow the trend for isotonic (spherical) lead nuclei. The noticeable difference in charge radii for ground and isomeric states of Tl183,184 has been observed, suggesting a larger deformation for the intruder-based 9/2- and 10- states compared to the ground states. An unexpected growth of the isomer shift for Tl183 has been found.