“…The presence of seven extra-core protons beyond the Z = 50 shell closure places the nucleus at the middle of the Z = 50-64 sub-shell where one may expect to observe a growth of collective behaviour in the level structure, in particular, at higher spin and excitation energy, in which, the π1h 11/2 intruder orbital has an important role to play. From the systematics of low-lying states in even-A, N = 80 isotones [1], the existence of 10 + isomers at a modest excitation energy, has been confirmed as arising due to two neutron holes in ν1h 11/2 orbit. From shell model systematics, it is known that the π2d 5/2 and π1g 7/2 single particle orbits lie very close to each other, thereby making the proton Fermi surface rather diffused.…”