The experimentally observed structure of the E2 transitions in the quasicontinuum for 168 Yb is analyzed. The valley ridge structure along the E y i = E y 2 diagonal in y-energy correlation spectra has been reproduced by a model simulation in which a spreading of the rotational decay strength r rot is introduced in regions of nuclear excitation energy U > UQ where the density of bands with slightly differing moments of inertia and alignment is high. The values of r rot and U 0 vary from 75 to 110 keV and from 1.25 to 1.0 MeV, respectively, in the energy range 780 < E y < 1160 keV.PACS numbers: 23.20.Lv, 21.lO.Pc

Band crossings are observed in the yrast a = --j-and + y negative-parity decay sequences in 157