Ground-state properties of neutron-deficient platinum isotopes

Abstract

The hyperfine structure splitting and the isotope shift in the ,~ = 266 nm transition of Pt isotopes within the mass range 183 _< A ~< 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 daugthers 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 ~95pt via triaxial 193-187pt to a strongly deformed nearly prolate t77pt.

In-gas-cell laser spectroscopy of the magnetic dipole moment of the N≈126 isotope Pt199

“…4(b), taking into account the isotope shift as a fixed parameter. The IS value was evaluated from the measured values for the 192,194,196,198 Pt isotopes, considering the linear relation of the isotope shift [25,26]. The value A ex = 1.17 ± 0.10 GHz for the λ 1 laser power 70 μJ/pulse and 88 kPa gas cell pressure was obtained as a best-fit result.…”

“…Here, B gs of the ground state is related to Q by B gs = −Q/0.685 GHz from Ref. [26], and this equation was used in the fitting. The line shape for each transition was fixed to that evaluated in the 198 Pt analysis.…”

“…Table II shows a summary of the measured IS for the wavelength λ 1 = 248.792 nm, measured isotopic variation of the mean-square charge radius (these values are referred from Ref. [26]) and quadrupole deformation parameters calculated using the droplet model [30]. The IS between two isotopes with mass number A and A , δν A,A = ν A 0 − ν A 0 , is expressed as…”

“…As a first step, the magnetic dipole moments of 199g Pt (Z = 78, N = 121, I π = 5/2 − , and t 1/2 = 30.8(2) min) ground state and 199m Pt (I π = (13/2) + , and t 1/2 = 13.6(4) s) isomeric state [23] were measured by in-gas-cell laser ionization spectroscopy. The nuclear structures of platinum isotopes with 178 A 198 have been well studied through measurements of μ, Q, and charge radius by laser spectroscopy [24][25][26][27][28]. In the lighter, neutron-deficient region 178 A 183, shape coexistence was found and has been discussed in relation to the charge radii evaluated from the measured isotope shift (IS) [28].…”

“…In the lighter, neutron-deficient region 178 A 183, shape coexistence was found and has been discussed in relation to the charge radii evaluated from the measured isotope shift (IS) [28]. For the heavier region 183 A 198, the prolate (183 A 188), triaxial (190 A 194), and oblate (196 A 198) shapes have been discussed and compared with theoretical models [24][25][26][27]. In the more neutron-rich region, a spherical shape is dominant toward the shell closure at N = 126 in the same way as seen for lead (Z = 82) and mercury (Z = 80) isotopes [29], predicted by the droplet model [30] with β 2 = 0.…”