Isovector Quadrupole Excitations in the Valence Shell studied in Projectile Coulomb Excitation

One-phonon states of heavy vibrational nuclei with mixed proton-neutron symmetry have recently been made accessible by the technique of projectile Coulomb excitation. Gamma-rays following Coulomb excitation of the nuclides Ce-136,Ce-138 and Xe-134 have been measured with the Gammasphere-array run in singles-mode. M1, E2, and E3 transition matrix elements from low-spin states were measured relative to the known B(E2;0(1)(+) -> 2(1)(+)) values. The 2(+) -> 2(1)(+) MI strength distributions up to about 2.7 MeV serve for identifying the main fragment of the 2(1,ms)(+), one-quadrupole phonon mixed-symmetry state. The data are presented and their significance is discussed.