Particle excitations and rotational modes in Nuclei with A = 70 -90

In nuclei in the mass region of $A \approx 70 - 90$ a variety of phenomena
is observed which are based on single-particle and collective motion of the
nucleons. We discuss the properties of Br and Rb isotopes with neutron numbers
of 38 - 48. In light Br isotopes ($N$ = 37, 38) rotational bands have been
observed up to spins of 65/2 and rotational frequencies of 1.8 MeV. Both
features can be described in terms of the cranked Nilsson-Strutinsky formalism.
In Rb nuclei with $N$ = 45, 47 we found regular magnetic dipole bands
evolving at high spin whereas the low-spin structure of those less deformed
nuclei is irregular. These magnetic dipole bands represent magnetic rotation,
a new rotational mode predicted by the tilted-axis cranking model.
In nuclei at $N$ = 48 we found small collectivity in low-spin states and
multiplets based on multi-particle excitations at high spin. These properties
are interpreted in terms of the shell-model.