On the 9/2$^{-}$ level excitation energy of odd Tl, Au and Ir isotopes

A semi-empirical method inspired by Blomqvist previous calculations of the excitation energy of the lowest 9/2/sup -/ state of /sup 201/Tl is applied to similar calculations in different Tl, Au and Ir isotopes. These semi-empirical estimates agree well with the experimental values of these excitation energies as well as with the energy differences deduced from the analysis of the total potential energy surfaces calculated microscopically with Nilsson's model. The same excitation energies are computed with a spherical HFBCS model which does not reproduce so well the available experimental data. An interpretation of these deviations is attempted.