The hyperfine structures of ScCl and ScF

The Fourier transform microwave spectra of gaseous ScF and ScCl have been m easured in their (1)Sigma(+) ground electronic states. Transitions have bee n observed for ScF (J = 1-0) and for both (SCCl)-Cl-35 and (SCCl)-Cl-37 (J = 1-0 and J = 2-1) in the ground vibrational state, and for (SCCl)-Cl-35 (J = 1-0 and J = 2-1) in the first excited vibrational state. The nuclear qua drupole coupling constants of Sc and of both isotopes of Cl, the spin-rotat ion constants for all the nuclei and the nuclear spin-nuclear spin constant s for both molecules, have been determined. From these hyperfine constants, the electronic structures of ScF and ScCl have been investigated and compa risons have been made to similar molecules. ScCl has been found to be highl y ionic. For (ScCl)-Cl-35, the equilibrium bond length has been reevaluated and the vibration frequency and dissociation energy have been estimated. A simple approach to account for the Sc quadrupole coupling constants has be en shown to be flawed. (C) 2000 Academic Press.