The electric monopole ($E0\mathrm{}$) transitions from the first and second excited $0^{+}$ states at 1130.3 and 1740.7 keV, respectively, in ${}_{}{}^{100}{}_{}{}^{}\mathrm{Ru}$ have been observed from the internal-conversion-electron studies of the decay of ${}_{}{}^{100}{}_{}{}^{}\mathrm{Rh}$. The monopole strength for the first excited $0^{+}$ state $\rho (E0;0_1^{+}-0_g^{+})<\mathrm{}0.11\mathrm{}$ is deduced as an upper limit. The dimensionless ratios of the reduced $E0\mathrm{}$- to $E2\mathrm{}$-transition probabilities $X$ are deduced: $X\left(\frac{E0;0_1^{+}-0_g^{+}}{E2;0_1^{+}-2_1^{+}}\right)=0.011\mathrm{}\pm 0.001,$ $X\left(\frac{E0;0_2^{+}-0_g^{+}}{E2;0_2^{+}-2_1^{+}}\right)=0.6\mathrm{}\pm 0.3$. The observed branching ratio of the monopole strength for the second excited $0^{+}$ state is $\frac{\rho (0_2^{+}-0_g^{+})}{\rho (0_2^{+}-0_1^{+})}=0.73\mathrm{}\pm 0.07$. The experimental results are compared with the theory on the basis of the collective vibrations of an axially and nonaxially deformed nucleus.

RADIOACTIVITY ${}_{}{}^{100}{}_{}{}^{}\mathrm{Pd}$ [from ${}_{}{}^{103}{}_{}{}^{}\mathrm{Rh}\mathrm{}(p,4n)\mathrm{}$]; measured $E_{\mathrm{ce}}$, $I_{\mathrm{ce}}$, $E_{\gamma }$, $I_{\gamma }$, $\gamma -\gamma$ coin ${}_{}{}^{100}{}_{}{}^{}\mathrm{Ru}$ deduced ICC, $B\left(E0\mathrm{}\right)\mathrm{}$, branching ratio $\frac{B\left(E0\mathrm{}\right)\mathrm{}}{B\left(E2\mathrm{}\right)\mathrm{}}$.

• Received 11 June 1974

DOI:https://doi.org/10.1103/PhysRevC.10.1996