Hyperfine structure in the A(4)Pi-X-4 Sigma(-) (0,0) band of MoN

The (0, 0) band of the A (4)Pi-X(4)Sigma(-) transition of MoN, between 590 and 635 nm, has been studied using the sub-Doppler technique of intermodula ted laser-induced fluorescence spectroscopy. Spectra taken at a resolution of about 60 MHz showed resolved hyperfine structure, which is caused princi pally by the unpaired 5s sigma electron in the ground state interacting wit h large magnetic moment of the Mo-95(24) and Mo-97(42) nuclear with nuclear spin I = 5/2. The hyperfine structures of the ground state vary with J in the manner expected for spin uncoupling from case (a(beta)) to case (b(beta J)). This band is notable for its complex appearance due to a combination of the high-spin multiplicity transition and the presence of seven isotopic species. Least-squares fits of the observed hyperfine line positions have yielded comprehensive sets of rotational, spin, and hyperfine parameters fo r the A (4)Pi and X(4)Sigma states of (MoN)-Mo-95 and (MoN)-Mo-97. The hype rfine parameters are interpreted and give information about the electron di stribution in the molecule. Improved molecular constants of other isotopome rs with zero Mo nuclear spin are also reported. (C) 2000 Academic Press.