E6andM5Transitions Observed inFe53mDecay

Photons corresponding to 3040.6-keV $E6\mathrm{}$ and 1712.6-keV $M5\mathrm{}$ transitions have been observed from the decay of 2.6-min ${\mathrm{Fe}}^{53m}$. They have intensities of 2 × ${10}^{-4\mathrm{}}$ and 7 × ${10}^{-3\mathrm{}}$, respectively, compared with the 701.1-keV $E4\mathrm{}$ isomeric transition that is primarily responsible for depopulating ${\mathrm{Fe}}^{53m}$. These correspond to retardations of 650 and 43 over simple single-particle estimates.