  The collective structure of atomic nuclei intermediate between spherical and
quadrupole deformed structure presents challenges to theoretical understanding.
However, models have recently been proposed in terms of potentials which are
soft with respect to the quadrupole deformation variable beta. To test these
models, information is needed on low-spin states of transitional nuclei. The
present work involves measurement of electromagnetic decay properties of
low-spin states for nuclei in the A=100 (gamma-soft) and N=90 (axially
symmetric) transition regions. Population in beta-decay and thermal neutron
capture are used, and measurements are carried out using gamma-ray coincidence
spectroscopy, fast electronic scintillation timing, and gamma-ray induced
Doppler broadening techniques, in experiments at Yale, TRIUMF ISAC, and the
ILL. To facilitate interpretation of these nuclei, a new approach is developed
that simplifies the application of the geometric collective model by use of
scaling properties. Solutions are also obtained for the E(5) Hamiltonian for
finite well depth.
