Laser spectroscopy of the A3Φi-X3Φi and B3Φ4-X3Φ4 transitions of iridium monofluoride (IrF) This article is part of a Special Issue on Spectroscopy at the University of New Brunswick in honour of Colan Linton and Ron Lees.

Laser-induced fluorescence spectra of iridium monofluoride (IrF) have been obtained at both low and high resolution. Two transitions have been observed; based on the rotational analysis of the high-resolution spectra, they have been assigned as A3Φi-X3Φi and B3Φi-X3Φi. For the X (ground) and B states, only the lowest Ω = 4 components have been observed, while for the A state, the two lowest components, Ω = 4 and 3, were detected. A global fit to all of the high-resolution data (six bands of A-X and five of B-X) yielded a complete set of molecular constants for all three states of both 191IrF and 193IrF. The v = 3 level of the A3Φ4 state was found to be heavily perturbed and many extra lines belonging to the perturbing state were observed for each isotopologue. A deperturbation analysis showed that the perturber is an Ω = 5 state, and molecular parameters for this state were obtained.