Effect of atomic charge state on nuclear lifetimes:Au197

The mean life of the 77.3-keV level in ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ has been measured simultaneously in neutral gold atoms and in atoms with a mean charge of $\overline{q}=+9.5\mathrm{}\pm 1.5$. Mean lives of ${\tau }^0=2.76\mathrm{}\pm 0.03$ nsec and ${\tau }^{+9.5\mathrm{}}=2.84\mathrm{}\pm 0.12$ nsec were obtained. These results indicate that even the removal of 10 electrons from this atom does not affect the electronic structure of the inner shells, and therefore has little effect on the internal-conversion coefficients and lifetime of this nuclear state. These results are in good agreement with both relativistic and nonrelativistic calculations.