SUBNANOSECOND ISOMERS IN SN-105,SN-107

The lifetimes of excited states in Sn-105.107 were measured using a plunger improved to cover a recoil distance up to 9.5 mm. In Sn-105, T-1/2(17/2(+)) = 0.38(5) ns and T-1/2(7/2(+)) = 0.33(8) ns. In Sn-107, T-1/2(17/2(+)) = 0.40(6) ns and T-1/2(7/2(+)) = 0.9(2) ns. The 7/2(+) --> 5/2(+) M1 transitions are l-forbidden by a factor of about 10(2): B(M1) = 0.008 W.u. in Sn-105 and B(M1) = 0.007 W.u. in Sn-107. From B(M1, 17/2(+) --> 15/2(+)) values major configurations of the 17/2(+) and 15/2(1.2)(+) states were deduced as follows: \17/2(+)] approximate to vd(5/2)(vg(7/2))(6+)(2), \15/2(1)(+)] approximate to vg(7/2)(vd(5/2))(4+)(2) + some admixture of vd(5/2)(vg(7/2))(6+)(2), \15/2(2)(+)] approximate to [vd(5/2)(vg(7/2))(6+)(2)](15/2).