Uncommon decay branching ratios of spin-one states in the rare-earth region and evidence for K mixing.

In nuclear resonance fluorescence (NRF) measurements of well deformed rare-earth nuclei we observe for most of the excited {ital J}=1 levels of both parities the ground-state transition and the corresponding transition to the 2{sub 1}{sup +} state. The experimental branching ratios {ital R}{sub exp}={ital B}(1{r arrow}2)/{ital B}(1{r arrow}0) are compared with the predictions of the Alaga rules. The examination of 171 levels found in NRF experiments yields that most values of {ital R}{sub exp} are in good agreement with the Alaga rules. Nevertheless, some branching ratios suggest a possible mixing of {ital K} values.