Accurate masses of neutron deficient nuclides close to Z=82

Abstract Mass measurements with the Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN are extended to nonsurface ionizable species using newly developed ion-beam bunching devices. Masses of 179–197 Hg, 196,198 Pb, 197 Bi, 198 Po and 203 At were determined with an accuracy of 1×10 −7 corresponding to δm≈20  keV. Applying a resolving power of up to 3.7×10 6 ground and isomeric states of 185,187,191,193,197 Hg were separated. First experimental values for the isomeric excitation energy of 187,191 Hg are obtained. A least-squares adjustment has been performed and theoretical approaches are discussed to model the observed fine structure in the binding energy.