Decay of the Odd-Odd IsomerTl198m

The electron spectrum of ${\mathrm{Tl}}^{198m}$ has been investigated in a 25-cm double-focusing beta spectrometer with a resolution of approximately 0.4 percent. The electron lines have been assigned to three gamma rays with energies (in kev) 261.5, 284, and 48.4, respectively. The multipolarities assigned from conversion ratio and lifetime considerations are $M4\mathrm{}$, $M1+E2\mathrm{}$, and $E2\mathrm{}$, respectively. A tentative decay scheme is proposed which is consistent with all the available data.