Sequences of rotational resonances (rotational bands) and corresponding ant
iresonances are observed in ion collisions. In this paper we propose a desc
ription which combines collective and single-particle features of cluster c
ollisions. It is shown how rotational bands emerge in many-body dynamics, w
hen the degeneracies proper of the harmonic oscillator spectra are removed
by adding interactions depending on the angular momentum. These interaction
s can be properly introduced in connection with the exchange forces and the
antisymmetrization, and give rise to a class of non-local potentials whose
spectral properties are analyzed in detail. In particular, we give a class
ification of the singularities of the resolvent, which are associated with
bound states and resonances. The latter are then studied using an appropria
te type of collective coordinates, and a hydrodynamical model of the trappi
ng, responsible for the resonances, is then proposed. Accordingly, we deriv
e, from the uncertainty principle, a spin-width of the unstable states whic
h can be related to their angular lifetime.