New Metastable State of Mercury

A state of Hg with an excitation potential of 9 v has been found to be metastable. It is most likely the ${}_{}{}^3{}_{}{}^{}D_3^{}{}_{}{}^{}$ state of the configuration ${\mathrm{}\left(5d\right)\mathrm{}}^9{\mathrm{}\left(6s\right)\mathrm{}}^2\mathrm{}\left(6p\right)\mathrm{}$. It is possible that other members of this configuration also are long-lived. The use of alkali metals as detectors for metastable atoms is discussed.