Knowledge Bank

The hyperfine interaction constants of TlCl have been calculated from the radiofrequency spectra. The transition frequencies were measured with a molecular beam electric resonance spectrometer under conditions of very weak electric and magnetic $fields.1$ An experimental linewidth of 500 Hz allowed us to determine for the first time the values of the tensor and scalar parts of the spin-spin interaction, $C3$ and $C4$. The quadrupole coupling constant for the chlorine nucleus, eqQ, and the spin-rotation coupling constants, $CC1$ and $CT1$, have been determined with greater precision than was possible in earlier $investigations.2,3$ The calculated constants (in kHz) for all four isotopic species and several rotational and vibrations states are: [FIGURE]