A search for high-spin isomeric states in the 138,139Ce anc 141,142Nd nuclei has been made using (α, xn) reactions and the intrinsic pulsing of the 225-cm Stockholm cyclotron. In 138Ce, besides the known 7- isomeric state at 2 128.8 keV, another one at 3 538.5 keV, 10+, with T 1/2 = (78 ± 5) ns has been found. In 139Ce a new isomeric state at 2 631.5 keV, 19/2-, with T 1/2 = (70 ± 5) ns has been identified. Also in 141Nd a high-spin isomeric level exists probably at 3 104.9 keV with T 1/2 = (26 ± 5) ns. In 142Nd the level at 3 453.0 keV, with spin I = 6, shows a half-life T 1/2 = (1.3 ± 0.1) ns while that at 4 718.5 keV, I = 8, decays with a half-life of about 0.8 ns. The time distributions in 142Nd show that the 3 242.9 keV, I = 7, or the 3 456.2 keV, I = 8, level is also delayed and decays with T 1/2 = (1.6 ± 0.1) ns. The deduced transition probabilities are compared to theoretical predictions.

The lifetimes of the excited states in 133Cs have been measured by the delayed coincidence technique. The results are:The 81.0 keV level: T½ = 6.27 ± 0.04 nsThe 160.5 keV level: T½ = 190 ± 15 psThe 384 keV level: T½ = 40 ± 20 psThe 437 keV level: T½ ⩽ 150 psA comparison is made between experimental and theoretical transition probabilities. The 160 keV state is interpreted as a three quasi particle state.

Half-lives of the 181.8 keV level (1.91 ± 0.06 ns) and the 477.9 keV level (68 ± 16 ps) have been measured by the delayed coincidence technique. Upper limits for the half-lives of two levels in 101Ru are reported.

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