Ce2

Ce2 is the diatomic molecule composed of two cerium atoms. It has been investigated in both experimental and theoretical studies as part of the broader investigation of bonding in lanthanide elements. In gas-phase experiments, Ce2 can be generated by techniques such as laser ablation of cerium metal followed by rapid cooling and observation in a molecular beam, and its electronic states have been probed by spectroscopic methods. Matrix isolation studies at cryogenic temperatures have also contributed to understanding its excited-state structure.

The electronic structure of Ce2 is complex due to the involvement of cerium’s 4f, 5d, and 6s electrons, leading to multiple low-lying electronic states and strong electron correlation. As a result, bond order and bond length can vary with the electronic state, and relativistic effects, including spin–orbit coupling, play a significant role in accurately describing the molecule. Computational work on Ce2 commonly employs multireference methods to capture near-degeneracy and correlation, sometimes supplemented by relativistic effective core potentials. Density functional theory has been used as well, though f-electron localization presents challenges for some functionals.

Ce2 is typically short‑lived under ambient conditions and is primarily observed under controlled laboratory environments, such as high vacuum or cryogenic settings. It serves as a model system for studying metal–metal bonding in f-block elements and helps inform understanding of larger cerium clusters and related oxide species in catalysis and materials science. See also: cerium clusters, lanthanide diatomic molecules.