Nuclear hyperfine coupling constants of aluminium monoiodide determined by Fourier-transform microwave spectroscopy

The ground-state rotational spectrum of 27Al127I has been investigated by Fourier-transform microwave spectroscopy. AlI was generated by reaction of laser-ablated aluminium vapour with methyl iodide. The rotational constant (B0), nuclear quadrupole coupling constants (χaaAl,χaaI) and the nuclear spin-rotation constant of iodine (CbbI) have been re-determined with high precision. The nuclear spin-rotation constant of aluminium (CbbAl), the nuclear spin-spin constants (DaaAl,I,δAl,I) and the dependence of the coupling constant χaaI on J(χJI) were determined. DaaAl,Iand δAl,I agree with calculated values and χJI is consistent in sign and magnitude with the known dependence of χaaI on vibrational state.