Hyperfine Structure in the Spectrum of Mercury Hydride*

Measurements of hyperfine structure splittings have been made from interferometer patterns for about 600 lines of the Hg199H spectrum in the A2Π–X2∑+ system. In many bands the splittings are measurable up to the termination of the branches. There are no observable splittings in the levels of the Π232 state. For the Π212 state the coupling is Hund’s case aβ with the “hyperfine doubling” contribution the predominant term in the hyperfine interaction energy. For the ground state the coupling is case bβS at very low J values and case bβJ otherwise. Generally, only transitions with ΔF=ΔJ=0, ±1 are observed. The interferometer patterns of about 400 lines of Hg201H have also been observed. The conclusions for Hg199H may be extended to Hg201H without contradictions.