THE LOW LYING ELECTRONIC STATES OF CeO, PrO, EuO, and YbO

Author Institution: Department of Chemistry, Massachusetts Institute of Technology Cambridge; Physical Chemistry Laboratory, Oxford University Oxford; Department of Physics, University of New Brunswick Fredericton. N.B.; Department of Chemistry, Massachusetts Institute of Technology Cambridge; Department of Chemistry, Massachusetts Institute of Technology Cambridge; Department of Chemistry, Massachusetts Institute of Technology CambridgeThe lowest energy electronic states of CeO and PrO are Found to arise from fs and $f^{2}s$ free $M^{2+}-$ ion configuration perturbed by an $O^{2-}$ ligand. EuO and YbO are unique among the lanthanide Oxides in that their lowest electronic configuration is $f^{N}$ rather than $f^{N-1}S$. An $^{8}\Sigma^{-}-{^{8}\Sigma^{-}}$ transition of EuO has been partially analyzed. In order to evolve and test a Ligand Field model for the electronic structure of the LnX and $LnX^{+}$ (X = O,S,H,F,Cl,Br,I) molecules, certain critical energy level splitting must be observed