Monopole strength and shape coexistence in the A≃100 mass region

Half-lives of 5.60(15) and 1.58(4) ns were measured for the $0_2^{+}$ levels in ${}_{}{}^{100}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$, respectively, using a β-γ-γ fast timing method. Analysis of the revised ρ(E0) systematics in the crucial A≃100 region indicates that high values of ρ(E0) do not by themselves imply strong configuration mixing between two coexisting states as presently assumed.