  The similar behavior of the B(E1) values of the recently observed 13- odd
tensor E1 isomers and the B(E2) values of the 10+ and 15- even tensor E2
isomers in the Sn-isotopes has been understood in terms of the generalized
seniority for multi-j orbits by using the quasi-spin scheme. This simple
approach proves to be quite successful in explaining the measured transition
probabilities and the corresponding half-lives in the high-spin isomers of the
semi-magic Sn-isotopes. Hence, we show for the first time the occurrence of
seniority isomers in the 13- Sn-isomers, which decay by odd-tensor E1
transitions to the same seniority states.
