Splitting of the 2+ mixed symmetry mode in the proximity of the N=82 ishell closure

Themixed symmetry 2+ states in theN = 84 isotones 142Ce and 144Nd are investigatedwithin the quasiparticlephonon model, with special attention to theirM1 decay to the lowest symmetric 2+ state. The observed pronounced splitting of the M1 strength is shown to be caused by the phonon coupling, made quite effective by the peculiar shell structure of the two-valence neutrons above the N = 82 shell closure