Systematics of isomeric configurations in N=77 odd-Z isotones near the proton drip line

The systematics of the πh11/2 νh11/2 and πh11/2 νs1/2 isomeric configurations was studied for the odd-Z N=77 isotones near the proton drip line. The isomeric decays in Eu140, Tb142, Ho144, and Tm146 were measured by means of x-ray, γ-ray, and charged particle spectroscopy at the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility (ORNL). The spin and parity of Iπ=8+ and 5- were deduced for the isomers in Eu140 and Tb142. New decay schemes were established, and the half-lives of the 8+ isomers were measured to be 302(4) ns for Eu140m2 and 25(1) μs for Tb142m2. No evidence for the expected 1+ ground-state was found in the Ho144 decay data. The proton-emission from Tm146 was restudied. Five proton transitions were assigned to two proton-emitting states. The half-lives of 198(3) ms and 68(3) ms and the spin and parity values of Iπ=10+ and 5- were established for Tm146m and Tm146gs, respectively. For the first time for an odd-odd nucleus, the interpretation of the observed decay properties and structure of the proton-emitting states was made by accounting for deformation and proton and neutron coupling to the core excitations. A complex wave-function structure was obtained, with dominating components of πh11/2 νh11/2 for the 10+ isomer and πh11/2 νs1/2 for the 5- ground state.