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The size of a ΔK=0 M1 excitation strength has been determined for the first time in a predominantly axially deformed even-even nucleus. It has been obtained from the observation of a rare K-mixing situation between two close-lying J^{π}=1^{+} states of the nucleus ^{164}Dy with components characterized by intrinsic projection quantum numbers K=0 and K=1. Nuclear resonance fluorescence induced by quasimonochromatic linearly polarized γ-ray beams provided evidence for K mixing of the 1^{+} states at 3159.1(3) and 3173.6(3) keV in excitation energy from their γ-decay branching ratios into the ground-state band. The ΔK=0 transition strength of B(M1;0_{1}^{+}→1_{K=0}^{+})=0.008(1)μ_{N}^{2} was inferred from a mixing analysis of their M1 transition rates into the ground-state band. It is in agreement with predictions from the quasiparticle phonon nuclear model. This determination represents first experimental information on the M1 excitation strength of a nuclear quantum state with a negative R-symmetry quantum number.

New data have been obtained for 185Os following the 176Yb(13C,4n)185Os reaction, extendingthe pseudo-Nilsson $\frac{1}{2}^{-},\frac{3}{2}^{-}[\mathaccent126{4}\mathaccent126{1}\mathaccent126{1}]$ doublet structure and the $\frac{7}{2}^{-}[\mathaccent126{4}\mathaccent126{0}\mathaccent126{4}]$ band to significantly higher spins. Gamma-ray branching ratio data have been analysed to obtain extensive B(M1) and B(E2) ratios for intraband and interband transitions. The data are compared with particle-rotor calculations based on the pseudo-Nilsson potential and the Woods-Saxon potential. The results indicate that the pseudo-Nilsson approximation provides a good description of the $\frac{1}{2}^{-}$ , $\frac{3}{2}^{-}[\mathaccent126{4}\mathaccent126{1}\mathaccent126{1}]$ bands up to the first band crossing;the difference in magnitude between the model predictions and data for the $\frac{7}{2}^{-}[\mathaccent126{4}\mathaccent126{0}\mathaccent126{4}]$ band may be attributed to a lower deformation for the higher-K structure.