Shape coexistence in atomic nuclei and its spectroscopic fingerprints

In the present discussion we concentrate on shape coexistence as obtained within a deformed single particle field as well as starting from the spherical shell model, incorporating deformation effects via the residual proton-neutron quadrupole interaction. We discuss in particular the appearance of shape coexisting phenomena in the Pb region. In a second part then, we present a number of experimental fingerprints that are able to recognize the appearance of shape coexisting phenomena or of shape mixing through the use of selective experiments (e.g., band structure, spectroscopic factors, static moments, E0 properties and α-decay)