The hyperfine structures of ScCl and ScF

The Fourier transform microwave spectra of gaseous ScF and ScCl have been measured in their (1)Sigma(+) ground electronic states. Transitions have been 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 quadrupole coupling constants of Sc and of both isotopes of Cl, the spin-rotation constants for all the nuclei and the nuclear spin-nuclear spin constants for both molecules, have been determined. From these hyperfine constants, the electronic structures of ScF and ScCl have been investigated and comparisons have been made to similar molecules. ScCl has been found to be highly 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 been shown to be flawed. (C) 2000 Academic Press.