The Molecular Beam Electric Resonance Method Study of Thallium Monochloride

The hyperfine structure of the first rotational state of Tl${\mathrm{Cl}}^{35}$ and Tl${\mathrm{Cl}}^{37}$ was studied by the molecular beam electric resonance method. Two types of molecular transitions were observed: the conventional $m_j$ transition in very weak and in strong Stark fields, the type previously studied in several alkali fluorides; the $\Delta J$ transition ($J=0\mathrm{}\to J=1\mathrm{}$), a molecular transition observed for the first time by molecular beam methods in this experiment.