Isotope shift of ¹⁸²Hg and an update of nuclear moments and charge radii in the isotope range ¹⁸¹Hg-²⁰⁶Hg

Abstract

The technique of collinear fast-beam laser spectroscopy has been used to measure the isotope shifts of the even-even isotopes of Hg (Z=80) in the mass range 182 ≤ A ≤ 198 at the on-line mass separator ISOLDE at CERN. The atomic transition studied (6s 6p³ P₂- 6s7s³ S₁,λ=546.1 nm) starts from a metastable state, which is populated in a quasi resonant charge transfer process. The resulting changes in nuclear mean square charge radii show clearly that ¹⁸²Hg follows the trend of the heavier, even, weakly oblate isotopes. Correspondingly the huge odd-even shape staggering in the light Hg isotopes continues and the nuclear shape staggering and shape coexistence persists down to the last isotope investigated, ¹⁸¹Hg. An update of isotope shift and hyperfine structure data for ^181-206Hg is given, with a revised evaluation of the differences in nuclear mean square charge radii and of spectroscopic quadrupole moments.