The lifetimes of several negative-parity states in ¹³⁴Ce excited via the reaction ¹²²Sn(¹⁶O, 4n)¹³⁴Ce at an incident beam energy of 76 MeV were measured for the first time by means of the recoil-distance Doppler-shift technique. The small $B(E2)$ transition strengths deduced from the lifetime data at the bottom of the negative-parity yrast states show spherical shape, in qualitative accordance with predictions of the shell model. At higher excitation energy along the negative-parity yrast line, the experimental $B(E2)$ transition strengths indicate an apparent gain of collectivity with increasing spin. The quadrupole deformation derived from the $B(E2)$ values at the bottom of the negative-parity yrast band confirms the predictions of the cranked Nilsson-Strutinsky Bogoliubov calculations. The systematic evolution in structure of the negative yrast states in Ce isotopes and $N=76$ isotones is discussed.

首次通过反冲距离多普勒频移测量了入射束能量为 76 MeV 的¹³⁴ Ce反应激发的¹³⁴ Ce中几种负奇偶态的寿命¹²² Sn( ¹⁶ O, 4 n ) ¹³⁴ Ce技术。小$乙(乙2)$根据壳模型的预测定性地，从负奇偶性 yrast 状态底部的寿命数据推导出的过渡强度显示球形。在沿负平价 yrast 线的更高激发能量下，实验$乙(乙2)$过渡强度表明，随着自旋的增加，集体性明显增加。四极变形由$乙(乙2)$负奇偶校验带底部的值证实了曲柄 Nilsson-Strutinsky Bogoliubov 计算的预测。Ce 同位素中负 yrast 态结构的系统演化和$N=76$ 讨论了同位素。