Decay of mass-separatedPom199andPog199

Sources of ${}_{}{}^{199}{}_{}{}^{}\mathrm{Po}_{}^{\mathrm{m}}{}_{}{}^{}$ and ${}_{}{}^{199}{}_{}{}^{}\mathrm{Po}_{}^{\mathrm{g}}{}_{}{}^{}$ have been produced and mass separated on line. Multiscaled spectra of γ rays, x rays, and conversion electrons, and γ-γ and γ-x-ray coincidences were measured. The M4 isomeric transition of the ${\mathrm{}(13/2)\mathrm{}}^{+}$ state of ${}_{}{}^{199}{}_{}{}^{}\mathrm{Po}$, with a half-life of 4.17 min, was observed for the first time, permitting the placement of the ${\mathrm{}(13/2)\mathrm{}}^{+}$ and ${\mathrm{}(5/2)\mathrm{}}^{\mathrm{-}}$ levels above the ${\mathrm{}(3/2)\mathrm{}}^{\mathrm{-}}$ ground state. Also, the placement of the ${\mathrm{}(13/2)\mathrm{}}^{+}$ state in Po together with previously reported α-decay Q values made possible the location of the ${\mathrm{}(13/2)\mathrm{}}^{+}$ isomeric state in ${}_{}{}^{195}{}_{}{}^{}\mathrm{Pb}$. From an analysis of γ-γ-t coincidence data and energy sums, 26 transitions were placed in a decay scheme between 23 levels in ${}_{}{}^{199}{}_{}{}^{}\mathrm{Bi}$. On the basis of systematics the population of a ${\mathrm{}(1/2)\mathrm{}}^{+}$ isomeric state in ${}_{}{}^{199}{}_{}{}^{}\mathrm{Bi}$ was deduced. The isomeric (M4) transition to the ${\mathrm{}(9/2)\mathrm{}}^{\mathrm{-}}$ ground state was not observable in the present data; its rate is at least 390 times less than the Weisskopf single particle estimate.