15min:

XIUJUAN ZHUANG AND TIMOTHY C. STEIMLE, Department of Chemistry and Biochemistry, Arizona State University, Tempe,AZ 85287; COLAN LINTON, Center for Lasers, Atomic and Molecular Sciences and Physics Department, University of New Brunswick, Fredericton, NB Canada E3B 5A3.

Recently the New Brunswick group reported on the field-free detection and analysis of the A³ ₄-X³ ₄ band system of IrF. Here we report on the analysis Q(4)(15922 cm^-1) branch feature of the (1,0) band of the ¹⁹¹IrF isotopologue of that system recorded at field strengths of up to 3000 V/cm. The spectra are surprisingly complex at the achieved resolution of 40 MHz due to the presence of both the ¹⁹¹Ir(I=3/2) and ¹⁹F(I=1/2) magnetic hyperfine splitting. The determined permanent electric dipole moment, µ_el, for the X³ ₄ state is compared with that recently determined for the X³ ₄ state of isovalent CoF. The trend in µ_el amongst the ground states of IrF, IrC and IrN will be discussed. Finally, a simple molecular orbital correlation diagram will be used to rationalize the change in µ_el upon excitation from the X³ ₄ to A³ ₄ state.