The Hyperfine Structure of the Mercury Triplet6P0123−7S13in Optical Excitation

The relative intensities of the hyperfine structure components of $\lambda 5461$, $\lambda 4358$ and $\lambda 4047$ in optically excited mercury vapor were computed by using the energy level scheme and intensity distribution calculated by Schüler and Keyston, with the assumption of complete absorption of $\lambda 2537$ and slight absorption of $\lambda 4358$. Since the excitation is in two steps, the ratio of the intensities of the components due to the less abundant isotopes to those due to the more abundant is much less than in the normal low pressure arc, in which the excitation of each isotope is proportional to its concentration These calculations were checked experimentally. Mercury vapor in a quartz resonance cell was excited optically by a low pressure mercury glow discharge in a helical quartz tube. This source was found to have the energy distribution predicted by Schüler and Keyston indicating small reversal. The hyperfine structure was photographed with a Lummer plate and the intensities determined from microphotometer records. The intensities from the optically excited vapor were found to agree within experimental error with the computed values.