Hyperfine interactions in the A³Φ₄ and X ³Φ₄ states of iridium monofluoride, IrF

Laser induced-fluorescence spectra of the 1-0 band of the A ³Φ₄ - X³Φ₄ transition of iridium monofluoride, IrF, have been obtained at near natural linewidth resolution using supersonic molecular beam techniques. The spectra show a complex, clearly resolved hyperfine structure which has significant contributions from the magnetic and quadrupole hyperfine terms in ¹⁹³Ir and ¹⁹¹Ir, both with I = 3/2, and the fluorine magnetic hyperfine term (I = 1/2). The spectra of both ¹⁹³IrF and ¹⁹¹IrF isotopologues have been assigned and analyzed. The hyperfine structure was interpreted with the aid of atomic hyperfine parameters, which were used to determine the configurational composition of the ground state and to estimate the individual molecular hyperfine parameters.