Permanent electric dipole moment of cerium monoxide

Stark spectra of the [16.5]2-X(1)2 and [16.5]2-X(2)3 transitions of cerium monoxide (CeO) have been obtained at a resolution of approximately 50 MHz. Analysis of the Stark spectra yielded permanent electric dipole moments, mu(el), of 3.119(8), 3.115(7), and 2.119(8) D for the X(1)2, X(2)3, and [16.5]2 states, respectively. The ground X(1)2 state dipole moment is shown to follow the trend shown by other lanthanide oxides. While most ab initio calculations tend to overestimate the ground state dipole moment, the value calculated by using pseudopotentials in which the 4f orbital participates in the chemical bonding (Dolg,M.; Stoll, H.; Preuss, H. THEOCHEM 1991, 231, 243] is in very good agreement with our experimental value.