Anomalies in the alpha-decay energies and half-lives of neutron-deficient Po isotopes

The transition rates of DeltaL = 0 alpha transitions in them lightest Po is otopes are considerably slower than the transition rates of the heavier one s, even leading to a considerable deviation in the classical Geiger-Nuttall plot. Evidence will be given that due to particle-hole excitations through the Z = 82 proton shell, the groundstate of the lighter Po isotopes become s deformed and direct alpha decay to the spherical groundstate of the corre sponding Ph isotopes is highly retarded.