GROUND-STATE PROPERTIES OF NEUTRON-DEFICIENT PLATINUM ISOTOPES

The hyperfine structure splitting and the isotope shift in the lambda = 266 nm transition of Pt isotopes within the mass range 183 less-than-or-equal-to A less-than-or-equal-to 198 have been determined by Resonance Ionization Mass Spectroscopy (RIMS) in combination with Pulsed-Laser Induced Desorption (PLID). The Pt isotopes were obtained at the on-line isotope separator ISOLDE-3/CERN as daughters of the primarily produced Hg isotopes. Magnetic moments, quadrupole moments, and changes in the mean-square charge radii are deduced and compared with results of a particle-triaxial rotor model and mean field calculations. Good agreement with experimental data (including nuclear level schemes and transition probabilities) can only be obtained if triaxial shape is admitted. The calculations yield a smooth transition in the shape of odd-A Pt nuclei from a slightly deformed, nearly oblate Pt-195 via triaxial Pt-193-Pt-187 to a strongly deformed nearly prolate 177Pt.